TONER SUPPLYING DEVICE AND ELECTROPHOTOGRAPHIC PRINTING DEVICE

Abstract

 In a toner supply apparatus and an electrophotographic printing apparatus, a liquid toner layer having a uniform film thickness in a roller width direction can be formed and supplied by providing a toner supply pan (61) for storing liquid toner, an anilox roller (52) capable of supplying the liquid toner by being rotated with a part thereof dipped into the liquid toner stored in the toner supply pan (61), a smoothing roller (53) capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the anilox roller (52), and a toner cover (67) disposed on an upstream side of a face-to-face contact portion between the anilox roller (52) and the smoothing roller (53) in the proximity thereof in rotating directions of the respective rollers (52, 53).

Description

Field

[0001] The invention relates to a toner supply apparatus for supplying stored toner as well as to an electrophotographic printing apparatus to which the toner supply apparatus is applied.

Background

[0002] Conventionally, an electrophotographic printing apparatus has been proposed, which develops liquid toner to an electrostatic latent image formed on a photoconductor using liquid toner in which toner composed of thermoplastic resin, pigment and the like is dispersed in a carrier, primarily transfers the liquid toner to an intermediate transfer member, further transfers the liquid toner to a surface of a print medium, and executes a print by fixing the toner in the transferred liquid toner to the print medium.

[0003] In the electrophotographic printing apparatus, the liquid toner is supplied from the reservoir to the developing roller via the smoothing roller by the anilox roller, and is transferred from a circumferential surface of the developing roller to a part of a photosensitive drum to which the electrostatic latent image is formed. In this case, the anilox roller has a groove or a concave portion formed on a circumferential surface thereof. Rotating the anilox roller with a part thereof dipped into the liquid toner causes the groove and the concave portion to carry the liquid toner, the liquid toner filled in the groove and the concave portion is homogenized by a blade, and the liquid toner is supplied to the smoothing roller with which the liquid toner is in face-to-face contact.

[0004] An example of the toner supply apparatus described above, a toner supply apparatus described is provided in Patent Literature 1.

Citation List

Patent Literature

[0005] Patent Literature 1: Japanese Patent Application Laid-open No. 2007-293177

Summary

Technical Problem

[0006] In the conventional toner supply apparatus described above, the anilox roller rotates with a part thereof dipped into the reservoir (vessel) and an outer circumferential surface thereof comes into contact with the blade, so that an amount of the liquid toner to be carried is adjusted as well as an amount of the liquid toner is homogenized in a width direction. However, since the liquid toner is supplied to the reservoir via a pipe, the liquid toner flows irregularly in the reservoir, and the amount of the liquid toner is dispersed in a width direction of the anilox roller. In this case, although the amount of the liquid toner carried by the anilox roller is homogenized by the blade, it is difficult to make a pressing force of the blade applied to the anilox roller uniform in the width direction.

[0007] An object of the invention is to solve the problem described above, and thereby to provide a toner supply apparatus capable of forming and supplying a liquid toner layer having a uniform film thickness in a width direction of a roller and an electrophotographic printing apparatus.

Solution to Problem

[0008] According to an aspect of the present invention, a toner supply apparatus includes: a toner supply pan for storing liquid toner; a toner supply roller capable of supplying the liquid toner by being rotated with a part thereof dipped into the liquid toner stored in the toner supply pan; a toner conveying roller capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the toner supply roller; and a toner staying member disposed on an upstream side of a face-to-face contact portion between the toner supply roller and the toner conveying roller in the proximity thereof in rotating directions of the respective rollers.

[0009] Accordingly, when the toner supply roller rotates while being dipped into the liquid toner in the toner supply pan, the toner supply roller rotates with the liquid toner deposited on an outer circumferential surface thereof and supplies the liquid toner to a surface of the toner conveying roller at the face-to-face contact portion between the toner supply roller and the toner conveying roller. At the time of this process, since the toner staying member is disposed in the proximity of the face-to-face contact portion between the respective rollers, an amount of the liquid toner having a thickness equal to or more than a thickness with which the liquid toner can pass through the face-to-face contact portion is stayed at the face-to-face contact portion by the toner staying member. It is then possible to provide a liquid toner layer having passed through the face-to-face contact portion with a predetermined thickness and to appropriately supply the liquid toner onto the surface of the toner conveying roller. As a result, the toner conveying roller can form a liquid toner layer having a film thickness uniform in a width direction on the surface thereof.

[0010] Advantageously, in the toner supply apparatus, the toner staying member includes a first cover portion for covering a circumferential surface of the toner supply roller and a second cover portion for covering a circumferential surface of the toner conveying roller.

[0011] Accordingly, since the toner staying member covers both the circumferential surfaces of the toner supply roller and the toner conveying roller at the face-to-face contact portion therebetween, the toner staying member can cause a sufficient amount of the liquid toner which can pass through the face-to-face contact portion between the respective rollers to stay at the face-to-face contact portion.

[0012] Advantageously, in the toner supply apparatus, the toner staying member includes a front surface cover portion for covering circumferential surface sides of the respective rollers facing the face-to-face contact portion and an end surface cover portion for covering end surface sides of the respective rollers.

[0013] Accordingly, since the toner staying member covers not only the respective circumferential surfaces of the toner supply roller and the toner conveying roller but also respective end surfaces thereof, the toner staying member can cause the sufficient amount of the liquid toner which can pass through the face-to-face contact portion between the respective rollers to stay at the face-to-face contact portion.

[0014] Advantageously, in the toner supply apparatus, the toner staying member is disposed so as to extend from the toner supply pan.

[0015] Accordingly, since the toner staying member covers from the toner supply pan to the face-to-face contact portion between the toner supply roller and the toner conveying roller, the toner staying member causes the liquid toner in the toner supply pan to appropriately stay up to the face-to-face contact portion between the respective rollers, so that the toner staying member can supply an appropriate amount of the liquid toner onto the surface of the toner conveying roller.

[0016] Advantageously, in the toner supply apparatus, the toner supply pan is configured by integrally joining a first pan positioned on an upstream side of the toner supply roller in a rotating direction thereof and a second pan positioned on a downstream side of the toner supply roller in a rotating direction thereof, and the toner staying member is disposed so as to extend from the second pan.

[0017] Accordingly, configuring the toner supply pan by dividing it into pieces makes it easy to manufacture and assemble the toner supply pan and to improve manufacturability. Furthermore, extending the toner staying member from the second pan can make it easy to dispose the toner staying member.

[0018] Advantageously, in the toner supply apparatus, the toner supply pan includes a toner supply portion for supplying the liquid toner to the first pan.

[0019] Accordingly, in the toner supply pan, since the toner supply portion is disposed on the first pan side and the toner staying member is disposed on the second pan side, the liquid toner flows from the toner supply portion to the toner staying member side in the toner supply pan, similarly to the rotating direction of the toner supply roller. Therefore, a temperature increase of the liquid toner can be suppressed by suppressing the staying liquid toner in the toner supply pan.

[0020] Advantageously, in the toner supply apparatus, the toner supply pan includes bearings disposed to respective side wall portions thereof in a width direction, respectively, respective ends of the toner supply roller are rotatably supported by the respective bearings, and the toner staying member is disposed so as to extend from the side wall portions.

[0021] Accordingly, a support structure of the toner supply roller can be simplified by supporting the toner supply roller by the respective side wall portions of the toner supply pan via the bearings, as well as a configuration can be simplified by providing the toner staying member from the respective side wall portions.

[0022] Advantageously, in the toner supply apparatus, the toner staying member is disposed as a member independent of the toner supply pan.

[0023] Accordingly, providing the toner staying member independent of the toner supply pan makes it possible to independently design the respective members, so that a degree of freedom of design can be improved.

[0024] Advantageously, in the toner supply apparatus, the toner staying member includes a flexible film member or elastic member, and a base end thereof is fixed to an end of the toner supply pan, whereas an extreme end thereof is extended to the face-to-face contact portion between the toner supply roller and the toner conveying roller.

[0025] Accordingly, using the flexible film member or elastic member as the toner staying member can appropriately deform the toner staying member depending on an amount of the staying liquid toner, as well as can achieve a simplification of structure and a cost reduction.

[0026] Advantageously, in the toner supply apparatus, the toner staying member includes a rod-like member and is disposed along the face-to-face contact portion between the toner supply roller and the toner conveying roller.

[0027] Accordingly, using the rod-like member as the toner staying member can achieve the simplification of structure and the cost reduction.

[0028] According to another aspect of the present invention, an electrophotographic printing apparatus includes: a feeder device capable of supplying a sheet of print media one by one; a printing device for transferring a toner image, which is obtained by transferring and developing liquid toner onto an electrostatic latent image on a photoconductor, onto the print medium supplied from the feeder device; a fixing device for heating and fixing the toner image transferred onto the print medium; and a delivery device for delivering the print medium on which the toner image is fixed by the fixing device. The printing device includes a printing unit for transferring the liquid toner onto a photoconductor on which the electrostatic latent image has been formed and developing the electrostatic latent image, a primary transfer member for transferring the liquid toner developed by the printing unit, and a secondary transfer member for forming a nip portion by being in contact with the primary transfer member and applying a bias voltage for transferring the liquid toner onto the print medium. The printing unit includes a toner supply pan for storing the liquid toner, a toner supply roller capable of supplying the liquid toner by being rotated with a part thereof dipped into the liquid toner stored in the toner supply pan, a toner conveying roller capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the toner supply roller, a photoconductor capable of receiving charged liquid toner by being rotated in face-to-face contact with the toner conveying roller and transferring the charged liquid toner to the primary transfer member, and a toner staying member disposed on an upstream side of a face-to-face contact portion between the toner supply roller and the toner conveying roller in the proximity thereof in rotating directions of the respective rollers.

[0029] Accordingly, in the printing unit, when the toner supply roller rotates while being dipped into the liquid toner of the toner supply pan, the toner supply roller rotates with the liquid toner deposited on the outer circumferential surface thereof and supplies the liquid toner onto the surface of the toner conveying roller at the face-to-face contact portion between the toner supply roller and the toner conveying roller. At the time of this process, since the toner staying member is disposed at the face-to-face contact portion between the respective rollers in the proximity thereof, the amount of the liquid toner having the thickness equal to or more than the thickness with which the liquid toner can pass through the face-to-face contact portion is stayed by the toner staying member. It is then possible to set the liquid toner layer having passed through the face-to-face contact portion to the predetermined thickness and to appropriately supply the liquid toner onto the surface of the toner conveying roller. As a result, the toner conveying roller can form the liquid toner layer having a uniform film thickness in the width direction on the surface thereof. Thereafter, the toner conveying roller transfers the liquid toner onto the photosensitive drum on which an electrostatic latent image has been formed and develops the liquid toner. The developed liquid toner is transferred onto the primary transfer member, and when a print medium is conveyed between the primary transfer member and the second transfer member, the liquid toner of the primary transfer member is transferred onto the print medium and printed thereon. As a result, a print accuracy and print quality can be improved.

Advantageous Effects of Invention

[0030] According to the toner supply apparatus and the electrophotographic printing apparatus of the present invention, since the toner staying member is disposed on the upstream side of the face-to-face contact portion between the toner supply roller and the toner conveying roller in the proximity thereof in the rotating directions of the respective rollers, the liquid toner layer having the uniform film thickness in the width direction of the rollers can be formed and supplied.

Brief Description of Drawings

[0031] 

FIG. 1 is a schematic view illustrating an electrophotographic printing apparatus according to an embodiment of the invention.

FIG. 2 is a schematic view illustrating a printing device of the embodiment.

FIG. 3 is a schematic view illustrating a printing unit of the embodiment.

FIG. 4 is a front view illustrating a toner supply apparatus of the embodiment.

FIG. 5 is a schematic view illustrating a flow of liquid toner caused by the toner supply apparatus of the embodiment.

FIG. 6 is an exploded perspective view of the toner supply apparatus.

FIG. 7 is a sectional view illustrating a support portion of an anilox roller in the toner supply apparatus.

FIG. 8 is a schematic view illustrating a modification of the toner supply apparatus.

FIG. 9 is a schematic view illustrating a modification of the toner supply apparatus.

FIG. 10 is a schematic view illustrating a modification of the toner supply apparatus.

Description of Embodiments

[0032] Preferable embodiments of a toner supply apparatus and an electrophotographic printing apparatus according to the invention will be described below in detail referring to accompanying drawings. Note that the invention is not restricted by the embodiment. When plural embodiments are available, the invention also includes embodiments configured by combining the respective embodiments.

Embodiment

[0033] FIG. 1 is a schematic view illustrating an electrophotographic printing apparatus according to an embodiment of the invention, FIG. 2 is a schematic view illustrating a printing device of the embodiment, FIG. 3 is a schematic view illustrating a printing unit of the embodiment, FIG. 4 is a front view illustrating a toner supply apparatus of the embodiment, FIG. 5 is a schematic view illustrating a flow of liquid toner caused by the toner supply apparatus of the embodiment, FIG. 6 is an exploded perspective view of the toner supply apparatus, and FIG. 7 is a sectional view illustrating a support portion of an anilox roller in the toner supply apparatus.

[0034] In the embodiment, as illustrated in FIG. 1, an electrophotographic printing apparatus 10 is a single-sided/double-sided printer using a liquid development electrophotographic system, and includes a feeder device 11, a printing device 12, a fixing device 13, a conveying device 14, and a delivery device 15.

[0035] The feeder device 11 has a pair of upper/lower feeder units 11a, 11b, and the respective feeder units 11a, 11b have feeder pile boards 21a, 21b and separator devices 22a, 22b as a sheet feed mechanism, respectively. The feeder pile boards 21a, 21b are used to place print sheets (print media) S stacked thereon in upper and lower positions. The separator devices 22a, 22b are used to sequentially pick up a sheet on top of the print sheets S stacked on the feeder pile boards 21a, 21b and feed it forward. In this case, the feeder pile boards 21a, 21b can move upward/downward in response to a supply of the print sheets S so that the separator devices 22a, 22b can keep a positional relation having approximately a constant height to the print sheets S.

[0036] The printing device 12 can execute a process color print of K (black), C (cyan), M (magenta), and Y (yellow). In this case, as illustrated in FIG. 1 and FIG. 2, the printing device 12 transfers a toner image, that is developed by transferring liquid toner to an electrostatic latent image on a photoconductor, onto a print sheet S supplied from the feeder device 11. That is, the printing device 12 has a backup roller (secondary transfer member) 31, an intermediate transfer member (primary transfer member) 32, and four printing units 33, 34, 35, 36 corresponding to the respective colors.

[0037] The backup roller 31 and the intermediate transfer member 32 are rollers having the same outside diameter (circumference) and can be driven in an arrow direction in synchronization with each other in a face-to-face contact state. A nip portion (transfer position) to which a predetermined pressure is applied is set to the face-to-face contact portion. The backup roller 31 is provided with grippers 31a disposed to an outer peripheral portion thereof in a circumferential direction at equal intervals. The grippers 31a can grip a leading end of a print sheet S supplied from the feeder device 11 and can guide the gripped print sheet S to the nip portion by rotating the backup roller 31. In contrast, the intermediate transfer member 32, for example, is configured by attaching a blanket made of conductive urethane rubber to an outer peripheral surface thereof, and the blanket is applied with a voltage-controlled or current-controlled bias.

[0038] The backup roller 31 is disposed so as to apply a predetermined pressure, for example, a pressure of about 1 to 13 kg/cm to the intermediate transfer member 32 at the nip portion described above. Accordingly, when the print sheet S is conveyed by the backup roller 31 and passes through the nip portion formed between the backup roller 31 and the intermediate transfer member 32, the print sheet S is applied with a predetermined nip pressure. Further, the backup roller 31 is applied with a transfer bias of, for example, about -1000 V (in the case of voltage control). Accordingly, a force for adsorbing the liquid toner, which is to be described later, to the backup roller 31 side is applied due to a difference between the bias voltage (about -1000 V) of the backup roller 31 and a bias voltage of the intermediate transfer member 32. Thereby, an electrostatic transfer of the liquid toner from the intermediate transfer member 32 to the print sheet S can be promoted.

[0039] The respective printing units 33, 34, 35, 36 are disposed side by side around the intermediate transfer member 32 along its rotating direction and have the same configuration except that they have different colors of liquid toner to be used. Accordingly, the printing unit 33 will be explained below in detail.

[0040] As illustrated in FIG. 2 and FIG. 3, the printing unit 33 forms an electrostatic latent image on a photosensitive drum 41 based on image data transmitted from a control device (not illustrated), supplies the liquid toner to a position corresponding to the electrostatic latent image, and transfers an image of the liquid toner formed on the photosensitive drum 41 onto the intermediate transfer member 32.

[0041] The liquid toner is made by dispersing particulate toner formed of thermoplastic material resin, pigment, and the like all over a liquid carrier and blending the particulate toner. Here, a petroleum solvent (for example, mineral oil and the like as a paraffin solvent without polarity) containing about 10 to 40%, by weight ratio, of the particulate toner with an average particle diameter of 1 to 2 µm is used as the carrier.

[0042] The printing unit 33 is configured to include the photosensitive drum (photoconductor) 41, a cleaning unit 42, a diselectrification unit 43, a charging device 44, an exposure device 45, and a developing device 46. The photosensitive drum 41 has a photosensitive layer on a circumferential surface thereof, the photosensitive layer being formed including a photosensitive agent such as amorphous silicon (a-Si), photosensitive polymer (organic photoconductor), and the like. The photosensitive drum 41 is in face-to-face contact with the intermediate transfer member 32 at a nip portion, and can transfer the liquid toner on the photosensitive drum 41 to the intermediate transfer member 32 side.

[0043] The photosensitive drum 41 has the cleaning unit 42, the diselectrification unit 43, the charging device 44, the exposure device 45, and the developing device 46 that are sequentially disposed therearound along a rotating direction of the photosensitive drum 41 from an upstream side and are facing the photosensitive layer formed on a surface of the photosensitive drum 41.

[0044] The cleaning unit 42 is configured to include a cleaning blade 42a, and can remove the liquid toner remaining on a circumferential surface of the photosensitive drum 41 and deliver the removed liquid toner to a toner collection path (not illustrated). That is, the cleaning blade 42a is a rectangular sheet member formed of an elastic material, supported so that an extreme end thereof comes into contact with the circumferential surface of the photosensitive drum 41, and can scrape off the liquid toner on the circumferential surface of the photosensitive drum 41.

[0045] The diselectrification unit 43 has a function for erasing a charge remaining on the photosensitive layer of the photosensitive drum 41. The charging device 44 is configured to include plural noncontact type charging units of a corotron type, a scorotron type, and the like disposed along a circumferential direction of the photosensitive drum 41. The charging device 44 has a function for uniformly charging the photosensitive layer of the photosensitive drum 41 to, for example, about 500 V.

[0046] The exposure device 45 includes a light-emitting device (LED array) having emitters (for example, LEDs) disposed along an axis direction of the photosensitive drum 41 in a rod-like state, and causes the respective LEDs to emit light based on the image data transmitted from the control device. That is, radiating light from the exposure device 45 onto a surface of the photosensitive layer of the photosensitive drum 41 charged uniformly by the charging device 44 erases the charge of the photosensitive layer in the portion to which the light is radiated, so that an electrostatic latent image can be formed on the photosensitive layer based on the image data. Note that, the light-emitting device may be configured to form the electrostatic latent image by scanning a semiconductor laser and the like based on the image data in place of the LED array.

[0047] The developing device 46 is configured to include a toner reservoir 51, an anilox roller 52, a smoothing roller 53, a developing roller 54, a toner charging unit 55, and toner collection units 56, 57, and can transfer the liquid toner to the portion of the photosensitive drum 41 to which the electrostatic latent image is formed.

[0048] The liquid toner is stored in the toner reservoir 51, and the liquid toner can be supplied to and discharged from the toner reservoir 51 so that a part of the anilox roller 52 can be dipped into the liquid toner. The anilox roller 52 is, for example, a metal roller, and concave portions (cells) suitable for supplying therearound the liquid toner in a desired film thickness are formed on an overall circumferential surface of the anilox roller 52. The anilox roller 52 can be driven in rotation together with the photosensitive drum 41.

[0049] The smoothing roller 53 is made of, for example, conductive rubber (urethane rubber), disposed between the anilox roller 52 and the developing roller 54 with its circumferential surface being in contact with the anilox roller 52 and the developing roller 54. Further, the smoothing roller 53 and the anilox roller 52 can be rotated in a direction where circumferential surfaces thereof travel in the same direction at a point where they are in contact with each other.

[0050] The developing roller 54 is made of, for example, conductive rubber and disposed so as to form a nip portion being in contact with the photosensitive drum 41, and can be rotated so that the circumferential surface of the photosensitive drum 41 and a circumferential surface of the developing roller 54 travel in the same direction. Further, a speed of the circumferential surface of the developing roller 54 is set to the same speed as that of the circumferential surface of the photosensitive drum 41. The toner charging unit 55 has a function for uniformly charging the liquid toner on the developing roller 54.

[0051] Accordingly, the contact of the developing roller 54 having the conductive property with the photosensitive drum 41 at the nip portion causes the liquid toner containing charged toner to be transferred from the circumferential surface of the developing roller 54 to the portion of the photosensitive drum 41 to which the electrostatic latent image has been formed. The developed liquid toner on the circumferential surface of the photosensitive drum 41 is transferred to the intermediate transfer member 32 at the nip portion, so that a liquid toner layer (toner image) including an image formed by the toner can be formed on a circumferential surface of the intermediate transfer member 32.

[0052] The toner collection unit 56 can remove and collect the liquid toner remaining on the circumferential surface of the developing roller 54. The toner collection unit 57 can remove and collect the liquid toner remaining on a circumferential surface of the smoothing roller 53. Both the toner collection units 56, 57 have approximately the same configuration, convey the remaining toner exfoliated from surfaces of the smoothing roller 53 and the developing roller 54 by the blade to a predetermined position, and collect the remaining toner in a toner collection pan 68 to be described later.

[0053] The toner supply apparatus of the embodiment applied to the developing device 46 will now be described. As illustrated in FIG. 4, the toner supply apparatus of the developing device 46 has a toner supply pan 61, the anilox roller (toner supply roller) 52, the smoothing roller (toner conveying roller) 53, and a toner staying member to be described later.

[0054] As described above, the anilox roller 52 is a metal roller having the concave portions (cells) suitable for supplying the liquid toner to a circumferential surface thereof in the desired film thickness, and can be driven in rotation in a predetermined direction (counterclockwise direction in FIG. 4).

[0055] The smoothing roller 53 has the circumferential surface being in contact with the anilox roller 52, and can be driven in rotation in a predetermined direction (counterclockwise direction in FIG. 4). Accordingly, the smoothing roller 53 can be rotated so that the circumferential surfaces of the smoothing roller 53 and the anilox roller 52 travel in the same direction at a face-to-face contact portion thereof.

[0056] Note that, although the embodiment is described assuming that the anilox roller 52 functions as the toner supply roller and the smoothing roller 53 functions as the toner conveying roller, the embodiment is not limited to the configuration. For example, the anilox roller 52 may be caused to be directly in face-to-face contact with the developing roller 54 without providing the smoothing roller 53. In this case, the developing roller 54 functions as the toner conveying roller. Further, plural rollers (toner conveying rollers), in addition to the smoothing roller 53, may be directly interposed between the anilox roller 52 and the developing roller 54.

[0057] The toner supply pan 61 reserves the liquid toner. It has a shape which is long in an axis direction of the anilox roller 52 and bent (or curved) along a lower circumferential surface of the anilox roller 52 in a circumferential direction as well as rising after traveling along end surfaces of the anilox roller 52 in the axis direction. The toner supply pan 61 is disposed at a predetermined interval to the circumferential surface and the end surfaces of the anilox roller 52.

[0058] The toner supply pan 61 is configured by integrally joining a first pan 62 positioned on an upstream side of the anilox roller 52 in a rotating direction with a second pan 63 positioned on a downstream side of the anilox roller 52 in the rotating direction. As illustrated in FIG. 4 and FIG. 6, the first pan 62 has a bottom portion 62a bent along the circumferential surface of the anilox roller 52, two first attachment portions 62b rising from the bottom portion 62a on the respective shaft end sides of the anilox roller 52 along the circumferential surface of the anilox roller 52, a second attachment portion 62c falling down from the bottom portion 62a so as to be away from the circumferential surface of the anilox roller 52, flange portions 62d formed along the end surfaces of the anilox roller 52, and an attachment piece 62e formed projecting from the bottom portion 62a in a side direction.

[0059] Further, the second pan 63 has a bottom portion 63a bent along the circumferential surface of the anilox roller 52, an attachment portion 63b falling from the bottom portion 63a so as to be away from the circumferential surface of the anilox roller 52, and flange portions 63c formed along the end surfaces of the anilox roller 52. The toner supply pan 61 is configured so as to be fixed integrally by plural bolts 61a with the second attachment portion 62c of the first pan 62 in intimate contact with the attachment portion 63b of the second pan 63. In the toner supply pan 61, the attachment piece 62e is fixed to a bracket 64 by plural bolts 61b, and the bracket 64 is coupled with the toner collection pan 68 to be described later.

[0060] Further, the toner supply pan 61 is provided with a toner supply portion 65 for supplying the liquid toner to the first pan 62. The toner supply portion 65 supplies the liquid toner in a toner reservoir tank (not illustrated) into the toner supply pan 61 by a feed pump. The toner supply portion 65 is fixed by plural bolts 65c in a state where an attachment plate 65a is in intimate contact, from inside, with the first attachment portions 62b of the first pan 62 that configures the toner supply pan 61. In the toner supply portion 65, the attachment plate 65a is fixed with three coupling portions 65b, 65c along the axis direction of the anilox roller 52, and a feed pipe 65d is coupled with the coupling portion 65b at a central portion. Further, the coupling portion 65b at the central portion is coupled to the coupling portions 65c on both the sides by coupling pipes 65e. Coupling pipes 65f extend from the coupling portions 65c on both the sides to the coupling portion 65b at the central portion. Coupling pipes 65g extend to respective end sides, and the coupling portions 65b on both the sides and the respective coupling pipes 65f, 65g pass through the attachment plate 65a.

[0061] Accordingly, the liquid toner is supplied to the feed pipe 65d, reaches the coupling portions 65c on both the sides from the coupling portion 65b at the central portion via the respective coupling pipes 65e, and is supplied to the toner supply pan 61 via the respective coupling portions 65b and the respective coupling pipes 65f, 65g. In this case, since the respective coupling portions 65b and the respective coupling pipes 65f, 65g communicate with the toner supply pan 61 at five positions equally divided in a width direction of the toner supply pan 61 and the liquid toner is supplied to the five positions, the liquid toner does not have an irregular supply pressure in the toner supply pan 61.

[0062] Further, the toner supply pan 61 is provided with respective side wall portions which are formed in an arc shape on both the sides thereof in a width direction by causing the flange portions 62d of the first pan 62 to continue to the flange portions 63c of the second pan 63, and bearings 66 are engaged with the side wall portions (flange portions 62d, 63c). As illustrated in FIG. 7 in detail, the anilox roller 52 is rotatably supported by respective shaft portions 52a thereof passing through the bearings 66.

[0063] As illustrated in FIG. 4 and FIG. 6, in the toner supply apparatus of the embodiment configured as described above, a toner cover 67 as the toner staying member is disposed in the proximity of the anilox roller 52 on an upstream side of a face-to-face contact portion between the smoothing roller 53 and the anilox roller 52 in the rotating direction of the respective rollers 52, 53. In this case, the toner cover 67 is disposed integrally with the toner supply pan 61 and extended from the second pan 63 integrally therewith.

[0064] That is, the toner supply pan 61 is extended up to the face-to-face contact portion with the smoothing roller 53 so as to be formed in a curved shape along the circumferential surface of the anilox roller 52 while keeping a predetermined interval between the bottom portion 63a of the second pan 63 and the circumferential surface of the anilox roller 52. Further, the toner supply pan 61 is extended up to a face-to-face contact portion with the smoothing roller 53 so as to be formed in a flat shape along the end surfaces of the anilox roller 52 while keeping the predetermined interval between the flange portions 63c of the second pan 63 and the end surfaces.

[0065] In this case, the toner cover 67 is configured by a portion which extends from the bottom portion 63a in the second pan 63 of the toner supply pan 61 to the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 and a portion in which the flange portions 63c in the second pan 63 extend up to the face-to-face contact portion. That is, the toner cover 67 has a front surface cover portion 67a for covering the circumferential surface sides of the respective rollers 52, 53 that face the face-to-face contact portion between the respective rollers 52, 53 and end surface cover portions 67b for covering the respective end surface sides of the respective rollers 52, 53.

[0066] Further, in the toner cover 67, the front surface cover portion 67a is extended from the second pan 63 of the toner supply pan 61 along the circumferential surface of the anilox roller 52 and bent along the circumferential surface of the smoothing roller 53 at the face-to-face contact portion with the smoothing roller 53. In this case, the toner cover 67 has a first cover portion 67c for covering the circumferential surface of the anilox roller 52 at the predetermined interval from the anilox roller 52 and a second cover portion 67d for covering the circumferential surface of the smoothing roller 53 at the predetermined interval from the smoothing roller 53. The toner cover 67 is opened in a state that the second cover portion 67d is not in contact with the circumferential surface of the smoothing roller 53 in its mid-point.

[0067] Further, in the toner cover 67, likewise the front surface cover portion 67a, the end surface cover portions 67b are extended from the second pan 63 of the toner supply pan 61 along the end surfaces of the anilox roller 52, and face the end surfaces of the smoothing roller 53 at the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53. That is, in the toner cover 67, the end surface cover portions 67b cover up to the nip position between the anilox roller 52 and the smoothing roller 53 at the predetermined interval.

[0068] Further, as illustrated in FIG. 4, the toner collection pan 68 is disposed below the toner supply pan 61 so as to receive the liquid toner which has overflown from the toner supply pan 61. Likewise the toner supply pan 61, the toner collection pan 68 is formed in a shape which is long along the axis direction of the anilox roller 52 and larger than the toner supply pan 61 and has a capacity capable of accommodating the toner supply pan 61. Accordingly, the toner collection pan 68 can receive the liquid toner which has overflown from the toner supply pan 61. The toner collection pan 68 can discharge the liquid toner received from the toner supply pan 61 from a discharge port 68a formed to a bottom.

[0069] As illustrated in FIG. 1, the fixing device 13 heats the toner image transferred onto the print sheet S and fixes the liquid toner layer (toner image) transferred onto an upper surface of the print sheet S. The fixing device 13 includes a heat roller 71, a drive roller 72, a support roller 73, and an endless conveyor belt 74. Accordingly, when the print sheet S is conveyed between the heat roller 71 and the conveyor belt 74 trained around the drive roller 72 and the support roller 73, since the liquid toner layer (toner image) is heated by the heat roller 71, the toner image can be fixed onto the print sheet S.

[0070] Incidentally, a first sheet conveying path S1 for the print sheets S is disposed between the feeder device 11 and the printing device 12 described above. A base end side of the first sheet conveying path S1 is branched to two paths which are connected to the respective feeder units 11a, 11b, and an extreme end side thereof is connected to the nip portion between the backup roller 31 and the intermediate transfer member 32. The first sheet conveying path S1 is provided with plural pairs of an upper conveying roller and a lower conveying roller 81 capable of being driven which are disposed from the feeder device 11 to the printing device 12 at predetermined intervals. In this case, the intervals between the respective conveying rollers 81 are shorter than a length of the print sheet S in a conveying direction, so that at least two sets of the conveying rollers 81 can convey the print sheet S while holding it.

[0071] Further, a second sheet conveying path S2 for the print sheets S is disposed between the fixing device 13 and the delivery device 15 and the conveying device 14 is disposed to the second sheet conveying path S2. A base end side of the second sheet conveying path S2 is connected to the fixing device 13, and an extreme end side thereof is connected to the delivery device 15 via the conveying device 14. The second sheet conveying path S2 is provided with plural pairs of an upper conveying roller and a lower conveying roller 82 capable of being driven which are disposed from the fixing device 13 to the delivery device 15 at predetermined intervals. In this case, the intervals between the respective conveying rollers 82 are shorter than the length of the print sheet S in the conveying direction likewise the respective conveying rollers 81, so that at least two sets of the conveying rollers 82 can convey the print sheet S while holding it.

[0072] An inverting device 91 for inverting a front surface and a back surface of a print sheet S is disposed in front of the conveying device 14 between the first sheet conveying path S1 and the second sheet conveying path S2. The inverting device 91 has a switching mechanism 92, a sheet switching path 93, conveying rollers 94, a sheet inverting path 95, switch back rollers 96, a sheet return path 97, and conveying rollers 98. The inverting device 91 is used in a double-sided print.

[0073] The switching mechanism 92 switches and conveys a print sheet S conveyed on the first sheet conveying path S1 to the conveying device 14 or to the sheet switching path 93. The conveying rollers 94 can supply the print sheet S supplied to the sheet switching path 93 to the sheet inverting path 95. The sheet inverting path 95 inverts the print sheet S. The switch back rollers 96 can be rotated forward and backward, guide the print sheet S supplied to the sheet switching path 93 to the sheet inverting path 95, and thereafter supply the print sheet S to the sheet return path 97. The print sheet S supplied to the sheet return path 97 is returned to the first sheet conveying path S1 by the conveying rollers 98 and supplied to the printing device 12 again.

[0074] The conveying device 14 conveys a printed print sheet S being conveyed on the second sheet conveying path S2 to the delivery device 15, and can convey the print sheet S horizontally while supporting a lower surface thereof by a belt member which can circulate.

[0075] The delivery device 15 has a delivery pile board 101, forward/backward position adjusting members 102,103, and a right/left position adjusting member 104. That is, when the printed print sheet S is conveyed along the second sheet conveying path S2, the conveying device 14 releases the print sheet S held thereby above the delivery device 15 and discharges the print sheet S. At the time, the forward position adjusting member 102 operates and determines a forward position of the print sheet S as well as the backward position adjusting member 103 determines a backward position of the print sheet S. Further, the right/left position adjusting member 104 determines right/left positions of the print sheet S.

[0076] A print job executed by the electrophotographic printing apparatus 10 of the embodiment configured as described above will be explained below.

[0077] In the electrophotographic printing apparatus 10 of the embodiment, as illustrated in FIG. 1, one of the two feeder units 11a, 11b in the feeder device 11 operates and feeds the print sheets S one by one. A print sheet S having been fed from the feeder device 11 is conveyed to the printing device 12 by the plural conveying rollers 81 on the first sheet conveying path S1. In the printing device 12, the backup roller 31 receives the leading end of the print sheet S with its grippers 31a opened, grips the leading end of the print sheet S by closing the grippers 31a, and conveys the held print sheet S by being rotated.

[0078] In contrast, in the intermediate transfer member 32, transferred onto the circumferential surface of the photosensitive drum 41 on which an electrostatic image to be transferred onto a first surface of the print sheet S is formed by the respective printing units 33, 34, 35, 36, are liquid toners of respective colors, i.e., K (black), C (cyan), M (magenta), Y (yellow) corresponding to the electrostatic image, an image is developed on the photosensitive drum 41, and the liquid toners transferred onto the circumferential surface of the photosensitive drum 41 are transferred onto the intermediate transfer member 32.

[0079] To explain the above-mentioned specifically, as illustrated in FIG. 5, when a liquid toner is supplied from the toner supply portion 65 into the toner supply pan 61, the liquid toner enters into a gap between the circumferential surface of the anilox roller 52 and an inner wall surface of the toner supply pan 61, and as the anilox roller 52 rotates, the liquid toner flows along the circumferential surface of the anilox roller 52 in the rotating direction thereof as well as flows also in the axis direction of the anilox roller 52. Note that a part of the liquid toner supplied from the toner supply portion 65 to the toner supply pan 61 flows in a direction opposite to the rotating direction of the anilox roller 52, overflows from the toner supply pan 61, and flows down into the toner collection pan 68.

[0080] As the anilox roller 52 rotates, the liquid toner in the toner supply pan 61 flows from the inner wall surface of the toner supply pan 61 to the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 along an inner wall surface of the toner cover 67. The liquid toner stays in the face-to-face contact portion (nip portion) between the anilox roller 52 and the smoothing roller 53 by the toner cover 67. In this process, a thickness of a liquid toner layer which can pass through the nip portion between the anilox roller 52 and the smoothing roller 53 is determined by a nip width and a nip pressure between the anilox roller 52 and the smoothing roller 53. Accordingly, causing a liquid toner, which forms a liquid toner layer having a thickness equal to or more than a thickness capable of passing through the nip portion, to stay in the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 by the toner cover 67 provides a liquid toner layer having passed through the face-to-face contact portion (nip portion) with a predetermined constant thickness, so that the liquid toner layer having a uniform thickness in the width direction can be formed on the surface of the smoothing roller 53.

[0081] Specifically, when it is assumed that the anilox roller 52 and the smoothing roller 53 have a radius r, it is preferable to cause the liquid toner to stay so that a (1/2)r or more can be covered in a right angle direction on an upstream side in the rotating directions of the respective rollers 52, 53 from a line connecting a center of the anilox roller 52 and a center of the smoothing roller 53. In the case, although the anilox roller 52 and the smoothing roller 53 have the same diameter (radius r), when they have a different diameter, a roller having a smaller diameter is selected as a subject.

[0082] After the liquid toner having been flown from the toner supply pan 61 to the face-to-face contact portion between the respective rollers 52, 53 by the toner cover 67 is supplied to the smoothing roller 53 in a necessary amount, an excessive liquid toner overflows from the second cover portion 67d and flows down into the toner collection pan 68.

[0083] Further, since almost all the liquid toner having been supplied into the toner supply pan 61 flows in the toner supply pan 61 in the same direction as the rotating direction of the anilox roller 52 and overflows without staying therein, a heat exchange efficiency is improved due to an increase of a contact area between the liquid toner and the anilox roller 52. The liquid toner whose temperature has been increased is efficiently cooled by the anilox roller 52.

[0084] In the liquid toner having supplied from the anilox roller 52 to the smoothing roller 53, the smoothing roller 53 is conveyed to the developing roller 54, the liquid toner of the developing roller 54 is charged by the toner charging unit 55 as illustrated in FIG. 3, and the developing roller 54 is caused to come into contact with the photosensitive drum 41. Thereby, the liquid toner containing charged toner is transferred from the circumferential surface of the developing roller 54 to a portion of the photosensitive drum 41 where an electrostatic latent image is formed and the liquid toner is developed. The developed liquid toner on the circumferential surface of the photosensitive drum 41 is transferred onto the intermediate transfer member 32, so that a liquid toner layer (toner image) including an image formed by the toner can be formed on the circumferential surface of the intermediate transfer member 32.

[0085] Thereafter, when the print sheet S held by the backup roller 31 has reached a nip portion between the backup roller 31 and the intermediate transfer member 33, the liquid toner (toner image) is transferred from the circumferential surface of the intermediate transfer member 32 onto the surface (first surface) of the print sheet S on the side where the surface is in contact with the intermediate transfer member 32.

[0086] The print sheet S having the liquid toner transferred onto the first surface is conveyed to the fixing device 13 and the upper surface (first surface) of the print sheet S is heated, thereby the liquid toner layer (toner image) transferred onto the first surface is fixed.

[0087] The print sheet S having the liquid toner fixed on the first surface is conveyed on the second sheet conveying path S2 by the plural conveying rollers 82. The front surface and the back surface of the print sheet S are inverted by the inverting device 91, and the print sheet S is conveyed to the printing device 12 again by the first sheet conveying path S1.

[0088] The print sheet S having been conveyed to the printing device 12 again is gripped by the grippers 31a of the backup roller 31 at the leading end thereof in the same manner as that described above, and conveyed by the backup roller 31. In the intermediate transfer member 32, transferred onto the circumferential surface of the photosensitive drum 41, on which an electrostatic image to be transferred onto a second surface of the print sheet S is formed by the respective printing units 33, 34, 35, 36, are liquid toners of respective colors, i.e., K (black), C (cyan), M (magenta), Y (yellow) corresponding to the electrostatic image. Then, an image is developed on the photosensitive drum 41, and the liquid toners transferred onto the circumferential surface of the photosensitive drum 41 are transferred onto the intermediate transfer member 32. When the print sheet S held by the backup roller 31 has reached the nip portion between the backup roller 31 and the intermediate transfer member 32, the liquid toner (toner image) is transferred from the circumferential surface of the intermediate transfer member 32 onto the surface (second surface) of the print sheet S on the side thereof where the surface is in contact with the intermediate transfer member 32.

[0089] The print sheet S having the liquid toner transferred onto the second surface is conveyed to the fixing device 13, and the liquid toner layer (toner image) transferred onto the upper surface (second surface) of the print sheet S is fixed by heating the second surface.

[0090] The print sheet S having the liquid toners fixed on the first surface and the second surface is conveyed to the conveying device 14 by the plural conveying rollers 82 on the second sheet conveying path S2, transferred to the delivery device 15 by the conveying device 14, and discharged by the delivery device 15.

[0091] Note that, in the explanation of the embodiment described above, although the toner staying member is composed of the toner cover 67 and extended from the toner supply pan 61 so as to be disposed integrally therewith, the embodiment is not limited to the configuration. For example, the toner cover as the toner staying member may be formed as a member (body) independent of the toner supply pan, and the toner cover may be joined to the second pan 63 in the toner supply pan by welding, bolts, and the like. In this case, the toner cover may be overlapped on the toner supply pan and joined thereto or the toner cover may be joined to the toner supply pan by abutting ends thereof with each other. Further, the toner cover may be formed as a member (body) independent of the toner supply pan and may be disposed away from the toner supply pan (second pan). In this case, the toner cover may be supported by the toner supply pan via a bracket and the like, or may be supported by other member in the vicinity thereof.

[0092] FIG. 8 to FIG. 10 are schematic views illustrating a modification of the toner supply apparatus.

[0093] As illustrated in FIG. 8, a toner cover 111 as the toner staying member is disposed on an upstream side of the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 in the proximity thereof in the rotating directions of the respective rollers 52, 53. In this case, the toner cover 111 is disposed independent of the toner supply pan 61 and supported by, for example, the toner supply pan 61 and the toner collection pan 68.

[0094] That is, the toner cover 111 has a surface cover portion 111a for covering the circumferential surface sides of the respective rollers 52, 53 which face the face-to-face contact portion between the respective rollers 52, 53, and end surface cover portions 111b for covering the respective end surface sides of the respective rollers 52, 53. In the toner cover 111, the surface cover portion 111a has a first cover portion 111c for covering the circumferential surface of the anilox roller 52 at a predetermined gap therefrom and a second cover portion 111d for covering the circumferential surface of the smoothing roller 53 at the predetermined gap. In the toner cover 111, the second cover portion 111d is opened without being in contact with the circumferential surface of the smoothing roller 53 in its mid-point.

[0095] Further, as illustrated in FIG. 9, a toner cover 121 as the toner staying member is disposed on the upstream side of the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 in the proximity thereof in the rotating directions of the respective rollers 52, 53. In this case, the toner cover 121 is made of a flexible resin film and has a base end fixed to an end of the toner supply pan 61 by a fixing screw 122, and an extreme end is extending toward the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53. The extreme end of the toner cover 121 may be disposed in the proximity of the circumferential surfaces of the respective rollers 52, 53 by being bent inside or outside so as to form a cylindrical portion (or a thick column portion). Note that the toner cover 121 may be made of a rubber elastic member which can be elastically deformed.

[0096] Accordingly, the liquid toner in the toner supply pan 61 is caused to flow from the toner supply pan 61 to the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 along the toner cover 121 by rotating the anilox roller 52. The liquid toner is stayed in the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 by the toner cover 121, so that a sufficient amount of the liquid toner is supplied onto the surface of the smoothing roller 53. An excess of the liquid toner in the face-to-face contact portion overflows from the extreme end of the toner cover 121 and flows down into the toner collection pan 68.

[0097] Further, as illustrated in FIG. 10, a toner rod (rod-like member) 131 as the toner staying member is disposed on the upstream side of the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 in the proximity thereof in the rotating directions of the respective rollers 52, 53. In this case, the toner rod 131 is supported by, for example, the toner supply pan 61 and the toner collection pan 68.

[0098] As described above, the toner staying member is not limited to the toner cover 67 and may be the toner covers 111, 121 and the toner rod 131, as well as may be a wire and the like. The toner staying member may be any member as long as it can cause the liquid toner, which is scraped off in the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 by rotating the anilox roller 52, to temporarily stay therein.

[0099] Further, although the toner cover 67 as the toner staying member described above is disposed from the toner supply pan 61 to the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53, and the toner covers 67, 111, 121 and the toner rod 131 are disposed only at the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53, this is because the toner collection unit 57 is disposed in the proximity of the smoothing roller 53. When the toner collection unit 57 is eliminated or disposed to a different location, the toner staying member may be extended upward to both the sides of the smoothing roller 53.

[0100] As described above, the toner supply apparatus of the embodiment is provided with the toner supply pan 61 for storing the liquid toner, the anilox roller 52 capable of supplying the liquid toner by being rotated with a part thereof dipped in the liquid toner stored in the toner supply pan 61, the smoothing roller 53 capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the anilox roller 52, and the toner cover 67 disposed on the upstream side of the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 in the proximity thereof in the rotating directions of the respective rollers 52, 53.

[0101] Accordingly, when the anilox roller 52 rotates while being dipped into the liquid toner of the toner supply pan 61, the anilox roller 52 rotate with the liquid toner deposited on the outer circumferential surface thereof and supplies the liquid toner onto the surface of the smoothing roller 53 at the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53. At the time of this process, since the toner cover 67 is disposed in the proximity of the face-to-face contact portion (nip portion) between the respective rollers 52, 53, the amount of the liquid toner having the thickness equal to or more than the thickness with which the liquid toner can pass through the face-to-face contact portion is stayed by the toner cover 67. It is then possible to provide a liquid toner layer having passed through the face-to-face contact portion with a predetermined thickness and to appropriately supply the liquid toner to the smoothing roller 53. As a result, the smoothing roller 53 can form a liquid toner layer having a uniform film thickness in the width direction on the surface thereof.

[0102] Further, in the toner supply apparatus of the embodiment, the toner cover 67 has the first cover portion 67c for covering the circumferential surface of the anilox roller 52 and the second cover portion 67d for covering the circumferential surface of the smoothing roller 53. Accordingly, the toner cover 67 covers the circumferential surfaces of both the rollers 52, 53 at the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53, so that the toner cover 67 can cause a sufficient amount of the liquid toner which can pass through the face-to-face contact portion between the respective rollers 52, 53 to stay at the face-to-face contact portion thereof.

[0103] Further, in the toner supply apparatus of the embodiment, the toner cover 67 has the front surface cover portion 67a for covering the circumferential surface sides of the respective rollers 52, 53 which face the face-to-face contact portion between the respective rollers 52, 53, and the end surface cover portions 67b for covering the end surface sides of the respective rollers 52, 53. Accordingly, the toner cover 67 covers not only the respective circumferential surfaces of the anilox roller 52 and the smoothing roller 53 but also the respective end surfaces thereof, so that the toner cover 67 can cause the sufficient amount of the liquid toner which can pass through the face-to-face contact portion between the respective rollers 52, 53 to stay at the face-to-face contact portion.

[0104] Further, in the toner supply apparatus of the embodiment, the toner cover 67 is disposed extending from the toner supply pan 61. Accordingly, since the toner cover 67 covers from the toner supply pan 61 to the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53, the toner cover 67 can cause the liquid toner in the toner supply pan 61 to appropriately stay up to the face-to-face contact portion between the respective rollers 52, 53. Therefore, the toner cover 67 can supply an appropriate amount of the liquid toner onto the surface of the smoothing roller 53.

[0105] Further, in the toner supply apparatus of the embodiment, the toner supply pan 61 is configured by integrally joining the first pan 62 positioned on an upstream side of the anilox roller 52 in the rotating direction thereof and the second pan 63 positioned on a downstream side of the anilox roller 52 in the rotating direction thereof. The toner cover 67 is disposed extending from the second pan 63. Accordingly, configuring the toner supply pan 61 by dividing it into pieces makes it easy to manufacture and assemble the toner supply pan 61 and to improve manufacturability. Furthermore, extending the toner cover 67 from the second pan 63 can make it easy to dispose the toner cover 67.

[0106] Further, the toner supply apparatus of the embodiment includes the toner supply portion 65 for supplying the liquid toner to the first pan 62 of the toner supply pan 61. Accordingly, in the toner supply pan 61, since the toner supply portion 65 is disposed on the first pan 62 side and the toner cover 67 is disposed to the second pan 63 side, the liquid toner flows from the toner supply portion 65 to the toner cover 67 side in the toner supply pan 61, similarly to the rotating direction of the anilox roller 52. A temperature increase of the liquid toner can be suppressed by suppressing a stay of the liquid toner in the toner supply pan 61 and improving a contact efficiency between the liquid toner and the anilox roller 52. As a result, it is possible to form a liquid toner layer having a uniform film thickness in the width direction of the anilox roller 52 by accelerating cooling of the liquid toner and suppressing melting of toner particles.

[0107] Further, in the toner supply apparatus of the embodiment, the respective side wall portions (flange portions 62d, 63c) of the toner supply pan 61 in the width direction are provided with the bearings 66, respectively. The respective shaft portions 52a of the anilox roller 52 are rotatably supported by the respective bearings 66. The toner cover 67 is disposed in a manner of being extended from the side wall portions. Accordingly, a support structure of the anilox roller 52 can be simplified by supporting the anilox roller 52 by the respective side wall portions of the toner supply pan 61 via the bearings 66, and a configuration of the toner supply apparatus of the embodiment can be simplified by providing the toner cover 67 from the respective side wall portions.

[0108] Further, the electrophotographic printing apparatus of the invention is configured to include the feeder device 11, the printing device 12, the fixing device 13, the conveying device 14 for conveying a print sheet S on which a toner image is fixed, and the delivery device 15, wherein the printing device 12 is provided with the printing units 33, 34, 35, 36, the intermediate transfer member 32, and the backup roller 31. Each of the printing units 33, 34, 35, 36 is provided with the toner supply pan 61 for storing liquid toner, the anilox roller 52 capable of supplying the liquid toner by being rotated with a part thereof dipped into the liquid toner stored in the toner supply pan 61, the smoothing roller 53 capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the anilox roller 52, the developing roller 54 capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the smoothing roller 53, the photosensitive drum 41 capable of receiving the liquid toner and transferring the liquid toner onto the intermediate transfer member 32 by being rotated in face-to-face contact with the developing roller 54, and the toner cover 67 disposed on the upstream side of the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53 in the proximity thereof.

[0109] Accordingly, in the printing units 33, 34, 35, 36, when the anilox roller 52 rotates while being dipped into the liquid toner of the toner supply pan 61, the anilox roller 52 rotates with the liquid toner deposited on the outer circumferential surface thereof and supplies the liquid toner onto the surface of the smoothing roller 53 at the face-to-face contact portion between the anilox roller 52 and the smoothing roller 53. Since the toner cover 67 is disposed at the face-to-face contact portion (nip portion) between the respective rollers 52, 53 in the proximity thereof, the amount of the liquid toner having the thickness equal to or more than the thickness with which the liquid toner can pass through the face-to-face contact portion is stayed by the toner cover 67. It is then possible to provide the liquid toner layer having passed through the face-to-face contact portion with the predetermined thickness and to appropriately supply the liquid toner to the smoothing roller 53. As a result, the smoothing roller 53 can form the liquid toner layer having the uniform film thickness in the width direction on the surface thereof. Thereafter, the smoothing roller 53 transfers the liquid toner onto the photosensitive drum 41 on which an electrostatic latent image has been formed via the developing roller 54 and develops the liquid toner, and the developed liquid toner is transferred onto the intermediate transfer member 32. When a print sheet S is conveyed between the intermediate transfer member 32 and the backup roller 31, the liquid toner on the intermediate transfer member 32 is transferred onto the print sheet S and printed thereon. As a result, a print accuracy and print quality can be improved.

[0110] Note that, in the embodiment described above, although the toner cover 67 as the toner staying member of the invention is provided with the first cover portion 67c for covering the circumferential surface of the anilox roller 52 and the second cover portion 67d for covering the circumferential surface of the smoothing roller 53, the embodiment is not limited to the configuration. The toner staying member of the invention is disposed on the upstream side of the face-to-face contact portion between the toner supply roller and the toner conveying roller in the proximity thereof in the rotating directions of the respective rollers. The toner staying member (first cover portion) may be bent from the first cover portion 67c without providing the second cover portion 67d and extend upward as it is so as to cover the face-to-face contact portion between the toner supply roller and the toner conveying roller.

Reference Signs List

[0111] 

10

electrophotographic printing apparatus

11

feeder device

12

printing device

13

fixing device

14

conveying device

15

delivery device

31

backup roller (secondary transfer member)

32

intermediate transfer member (primary transfer member)

33, 34, 35, 36

printing unit

41

photosensitive drum (photoconductor)

46

developing device

51

toner reservoir

52

anilox roller (toner supply roller)

53

smoothing roller (toner conveying roller)

54

developing roller (toner conveying roller)

55

toner charging unit

56, 57

toner collection unit

61

toner supply pan

62

first pan

63

second pan

65

toner supply portion

66

bearing portion

67, 111, 121

toner cover (toner staying member)

67a

front surface cover portion

67b

end surface cover portion

67c

first cover portion

67d

second cover portion

68

toner collection pan

131

toner rod (toner staying member)

Claims

1. A toner supply apparatus comprising:

a toner supply pan for storing liquid toner;

a toner supply roller capable of supplying the liquid toner by being rotated with a part thereof dipped into the liquid toner stored in the toner supply pan;

a toner conveying roller capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the toner supply roller; and

a toner staying member disposed on an upstream side of a face-to-face contact portion between the toner supply roller and the toner conveying roller in the proximity thereof in rotating directions of the respective rollers.

2. The toner supply apparatus according to claim 1, wherein the toner staying member includes a first cover portion for covering a circumferential surface of the toner supply roller and a second cover portion for covering a circumferential surface of the toner conveying roller.

3. The toner supply apparatus according to claim 1 or 2, wherein the toner staying member includes a front surface cover portion for covering circumferential surface sides of the respective rollers facing the face-to-face contact portion and an end surface cover portion for covering end surface sides of the respective rollers.

4. The toner supply apparatus according to any one of claims 1 to 3, wherein the toner staying member is disposed so as to extend from the toner supply pan.

5. The toner supply apparatus according to claim 4, wherein the toner supply pan is configured by integrally joining a first pan positioned on an upstream side of the toner supply roller in a rotating direction thereof and a second pan positioned on a downstream side of the toner supply roller in a rotating direction thereof, and the toner staying member is disposed so as to extend from the second pan.

6. The toner supply apparatus according to claim 5, wherein the toner supply pan includes a toner supply portion for supplying the liquid toner to the first pan.

7. The toner supply apparatus according to any one of claims 1 to 6, wherein the toner supply pan includes bearings disposed to respective side wall portions thereof in a width direction, respectively, respective ends of the toner supply roller are rotatably supported by the respective bearings, and the toner staying member is disposed so as to extend from the side wall portions.

8. The toner supply apparatus according to any one of claims 1 to 3, wherein the toner staying member is disposed as a member independent of the toner supply pan.

9. The toner supply apparatus according to any one of claims 1 to 3, wherein the toner staying member includes a flexible film member or elastic member, and a base end thereof is fixed to an end of the toner supply pan, whereas an extreme end thereof is extended to the face-to-face contact portion between the toner supply roller and the toner conveying roller.

10. The toner supply apparatus according to claim 1 or 2, wherein the toner staying member includes a rod-like member and is disposed along the face-to-face contact portion between the toner supply roller and the toner conveying roller.

11. An electrophotographic printing apparatus comprising:

a feeder device capable of supplying a sheet of print media one by one;

a printing device for transferring a toner image, which is obtained by transferring and developing liquid toner onto an electrostatic latent image on a photoreceptor, onto the print medium supplied from the feeder device;

a fixing device for heating and fixing the toner image transferred onto the print medium; and

a delivery device for delivering the print medium on which the toner image is fixed by the fixing device, wherein the printing device includes

a printing unit for transferring the liquid toner onto a photoreceptor on which the electrostatic latent image has been formed and developing the electrostatic latent image,

a primary transfer member for transferring the liquid toner developed by the printing unit, and

a secondary transfer member for forming a nip portion by being in contact with the primary transfer member and applying a bias voltage for transferring the liquid toner onto the print medium,

wherein the printing unit includes

a toner supply pan for storing the liquid toner,

a toner supply roller capable of supplying the liquid toner by being rotated with a part thereof dipped into the liquid toner stored in the toner supply pan,

a toner conveying roller capable of receiving and conveying the liquid toner by being rotated in face-to-face contact with the toner supply roller,

a photoreceptor capable of receiving charged liquid toner by being rotated in face-to-face contact with the toner conveying roller and transferring the charged liquid toner to the primary transfer member, and

a toner staying member disposed on an upstream side of a face-to-face contact portion between the toner supply roller and the toner conveying roller in the proximity thereof in rotating directions of the respective rollers.

Drawing