Method and device for recycling developing material

Abstract

 A method and device for recycling a residual developing material on a photosensitive material after transfer step in an electrostatic copying apparatus wherein there is provided a blade member (12) capable of sliding to contact with and separating from the photosensitive material (2) upstream with respect to a corona charger (4) for charging the photosensitive material (2) before exposuring step along the moving direction of the photosensitive material (2). The blade member (12) slides to contact with the photosensitive material (2) during the time when a latent image is formed onto the photosensitive material (2) in a developing step, and separates from the photosensitive material (2) during the time when the latent image is not formed in the copying operation. The developing material accumulated on the photosensitive material (2) by means of the blade member (12) in the exposuring step travels to be stored at a developing device (6) according to the movement of the photosensitive material (2).

Description

[0001] The present invention relates to a method and a device for recycling a residual developing material on a photosensitive material after transfer step in an electrostatic copyina apparatus.

[0002] In a conventional eletrostatic copying apparatus using magnetic toner as a developing material, the residual toner residing on the photosensitive material after transfer step is removed by a blade member, a fur brush, or a magnetic brush cleaning device and stored in a container. Accordingly, the magnetic toner stored in the container is either thrown away by putting out the container from the frame of the copying apparatus or is returned back to the developi_nq device through a circulation pipe. The former prior art requires bothersome work to throw away the magnetic toner, while the latter prior art requires a intricate construction.

[0003] In another prior art where one copying operation is completed with two rotations of the photosensitive drum, a series of steps of charging, exposure, development, transfer are carried out during the first rotation, then the cleaning step is carried out by the developing device during the second rotation. According to this prior art, it is difficult that the developing device accomplishes both developing and cleaning operation completely, therefore, in practice, it has a defect that the developing and cleaning qualities are inferior.

[0004] It is an object of the invention to provide an improved method and an improved device for recycling the accumulated residual developing material to the developing device readily.

[0005] This object will be clear according to the description stated hereinbelow.

[0006] To accomplish the foregoing objectives, there is provided a method for recycling a residual developing material on a photosensitive material after transfer step of copying operation in an electrostatic copying apparatus comprising the steps of ; (a) providing a blade member capable of sliding to contact with and separating from the photosensitive material upstream with respect to a corona charger for charging the photosensitive material before an exposure step along the travelling direction of the photosensitive material, (b) driving the blade member to slide to contact with the photosensitive material during the time when a latent image is formed onto the photosensitive material in an exposure step, and to separate from the photosensitive material during the time when the latent image is not formed in the other steps of the copying operation, thereby the photosensitive material moves to allow the developing material accumulated on the photosensitive material by means of the blade member to reach and to be stored in a developing device when a latent image is not formed.

[0007] There is also provided a device for recycling a residual developing material on a photosensitive material after transfer step of copying operation in an electrostatic copying apparatus comprising ; (c) a blade member capable of sliding to contact with and to separate from the photosensitive material upstream with respect to a corona charger for charginc the photosensitive material before an exposure step along the rotational direction of the photosensitive material, (d) means for driving the blade member to slide to contact with the photosensitive material during the time when a latent image is formed onto the photosensitive material in an exposure step, and to separate from the photosensitive material during the time when the latent image is not formed in the other steps of the copying operation, thereby the photosensitive material moves to allow the developing material accumulated on the photosensitive material by means of the blade member to reach and to be stored in a developing device when a latent image is not formed.

[0008] According to the preferred embodiments of the invention, the photosensitive material is coated on a surface of a drum which is driven to rotate, the blade member is situated almost right above the drum. The blade member also may be situated at a position where the developing material accumulated by means of the blade member does not drop from the photosensitive material downstream along the rotational direction of the drum with respect to a position right above the drum.

[0009] Since a blade member is situated to slide to contact with the photosensitive material during the time when the latent imaqe is formed, and to separate from the surface of the photosensitive material when the latent image is not formed so that the blade member allow the accumulated developing material to be transported to and stored in the developing device, maintenance is exerted easily without employing complicated construction.

[0010] A detailed description of the invention will be made with reference to the accompanying drawings, which are to scale. Like numerals designate corresponding parts in the several figures.

Fig. 1 is a simplified sectional view showing the device according to the invention,

Fig. 2 is a simplified side view of the cleaning device 8, and

Fig. 3 is a sectional view taken along the line III-III of Fig. 2.

[0011] The following detailed description is of the best presently contemplated mode of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention since the scope of the invention best is defined by appendedsclaims.

[0012] The following detailed description is in reference to the Figures provided for an example of the invention. Referring to Fig. 1, there is shown a simplified sectional view of the device according to the invention. A photosensitive material 2 is coated on the whole surface of a drum 1 driven to rotate in a copying operation, or on at least a part of the surface of the drum 1 along the rotational direction. The drum 1 is driven to rotate along the direction indicated by the arrow 3. Around the neighboring location of the surface of the drum 1, there is located a corona charger 4 for charging the photosensitive material 2, an exposure device 5, a magnetic brush developing device 6, a corona charger 7 for transferring operation and a cleaning device 8 in this order along the rotational direction 3.

[0013] In the copying operation, the photosensitive material 2 cleaned by the cleaning device 8 is charged by the corona charger 4. The exposure device 5 forms an electrostatic latent image corresponding to the original document on the surface of the photosensitive material 2. The magnetic brush developing device 6 supplies magnetic toner of the surface of the magnetic brush 9 to the photosensitive material 2 so as to form the latent image into a visible image. The visible toner image is transferred onto a copying paper 10 concurrently transported in accordance with the rotation of the drum 2 in the rotational direction 3, by charging of the corona charger 7 for transferrina. After transfer step, the copying paper 10 is tranported to a fixing device (not shown). Further, the magnetic toner residing on the photosensitive material 2 after transfer step is removed by the cleaning device 8.

[0014] Acceding to one aspect of the invention, when the exposure device 5 does not radiate to form a latent image onto the photosensitive material 2, the cleaning device 8 does not achieve cleaning function and the residual magnetic toner on the photosensitive material 2 is transported to the magnetic brush developing device 6 so as to be adhered to the magnetic brush 9 and to return to the supplying container 11.'

[0015] Fig. 2 is a simplified side view of the cleaning device 8, and Fig. 3 is a sectional view taken along the line III- III of Fig. 2. The cleaning device 8 comprises (a) a blade member 12 which slides to contact with the surface of the photosensitive material 2 right above the drum l,or upstream with respect to the corona charger 4 for charging the photosensitive material 2 along the rotational direction 3 of the drum 1, (b) a rotary shaft 14 which is mounted rotatively on a pair of side plates 13a and 13b for supporting the drum 1 rotatively, and is parallel to the drum 1, (c) a securing member 15 for securing the blade member 12 to the rotary shaft 14, (d) an arm 16 havinq one end fixed to an end of the rotary shaft 14 outside of the side plate 13a, (e) driving means 17 connected with the other end of the arm 16, and (f) a spring 18 having one end connected with the rest position of the frame of the copyinc apparatus and the other end connected with the securing member 15, and forcing the blade member 12 to be spring-biased in the direction of separating the blade member 12 from the photosensitive material 2.

[0016] The blde member 12 made of soft or elastic material, such as urethane, to avoid scratching or other damage to photosensitive material 2 extends almost whole length of the drum 1. The blade member 12 is installed slantingly to separate from the photosensetive material 2 as it comes downstream along the rotational direction 3 of the drum 1, to allow the one end 12a of the blade member 12 to slide to contact with the photosensitive material 2. The other end 12b of the blade member 12 is supported by the rotary shaft 14. The driving means 17 comprises an electromagnetic coil 19, a plunger 20 which is capable of moving along the axis of the electromagnetic coil 19, and a spring 21 forcing the plunger 20 to be spring-biased in the direction of separating from the electromagnetic coil 19. The other end of the arm 16 is pin-connected with the plunger 20.

[0017] The driving means 17 has a function to draw the plunqer 20 into the electromaqnetic coil 19 against the force of springs 18 and 21 in an excited state of the electromagnetic coil 19, and to release the plunger 20 from the electromagnetic coil 19 by the springs 18 and 21 in a non-excited state. Accordingly, in the excited state of the electromagnetic coil.19, the rotary shaft l4 rotates in the direction indicated by the arrow 22 (referred in Fig. 2), and thus the blade member 12 comes to slide to contact with the photosensitive material 2 against the force of the sprinq 18. In a non-excited state of the electromagnetic coil 19, the rotary shaft 14 rotates in the direction opposite to the arrow 22, and thus the blade member 12 comes to separate from the photosensitve material 2 as indicated in the imaginary line in Fig. 2. The electromagnetic coil 19 is regulated to be enerqized in response to a signal qenerated accordingly to a movable original document carrier or a movable portion of the exposure device. Except during the time when a latent imaqe is formed, the blade member 12 is separated from the photosensitive material 2.

[0018] Therefore, during the time when a latent image is formed, the residual magnetic toner on the photosensitive material 2 after transfer step, reaches the cleaning device 8 according to the rotation of the drum 1, and is accumulated by means of the blade member 12. The accumulated magnetic toner does not separate and drop from the photosensitive material 2, because the cleaning device 8 is situated almost right above the drum 1.

[0019] During the time when the corona charger 4 and the exposure device 5 are unabled and thus the latent image is not formed, the blade member 12 separates from the photosensitive material 2 as mentioned above, therefore the magnetic toner accumulated by means of the blade member 12 is transported to the magnetic brush developing device 6 according to the rotation of the drum 1. Then, the magnetic toner is adhered to the magnetic brush 9 and is brought into the supplying container 11.

[0020] Time when the blade member 12 is separated from the photosensitive material 2 is chosen to be during the time when the latent image is not formed, both in a single copyinq operation and a multiple copying operation.

[0021] According to another aspect of the invention, the photosensitive material 2 may be coated on an endless belt alternative to the drum 1. Though the copying apparatus set forth hereinbefore achieves a copying operation during a single rotation of the drum, the invention may be carried out in the copying apparatus wherein a copying operation is completed during two rotations of the drum 1. Also, the blade member 12 may be situated downstream along the rotational direction 3 of the drum 1 with respect to the position right above the drum 1, it is important according to the invention that the blade member 12 is situated at the position where the developing material accumulated by means of the blade member 12 does not drop from the drum 1.

Claims

1. A method for recycling a residual developing material of a photosensitive material (2) after transfer step of copying operation in an electrostatic copying apparatus comprising the steps of ;

providing a blade member (12) capable of sliding to contact with and separating from the photosensitive material (2) upstream with respect to a corona charger (4) for charging the photosensitive material(2) before an exposure step along the travelling direction of the photosensitive material (2), and

driving the blade member (12) to slide to contact with the photosensitive material (2) during the time when a latent image is formed onto the photosensitive material(2) in an exposure step, and to separate from the photosensitive material (2) during the time when the latent image is not formed in the other steps of the copying operation, thereby the photosensitive material (2) moves to allow the developing material accumulated on the photosensitive material (2) by means of the blade member (12) to reach and to be stored in a developing device (6) when a latent image is not formed.

2. A device for recycling a residual developing material on a photosensitive material (2) after transfer step of copying operation in an electrostatic copying apparatus comprising ;

a blade member (12) capable of sliding to contact with and separating from the photosensitive material (2) upstream with respect to a corona charger for charging the photosensitive material (2) before an exposure step along the rotational direction of the photosensitive material (2), and

means for driving the blade member (12) to slide to contact with the photosnsitive material (2) during the time when a latent image is formed onto the photosensitive material (2) in an exposure step, and to separate from the photosensitive material (2) during the time when the latent image is not formed in the other steps of the copying operation, thereby the photosensitive material (2) moves to allow the developing material accumulated on the photosensitive material (2) by means of the blade member (12) to reach and to be stored in a developing device (6) when a latent image is not formed.

3. A device as claimed in claim 2 characterised in that the photosensitive material (2) is coated on a surface of a drum (1) which is driven to rotate, the blade member (12) is situated almost right above the drum (1).

4. A device as claimed in claim 2 characterised in that the photosensitive material (2) is coated on a surface of a drum (1) which is driven to rotate, the blade member (12) is situated at a position where the developing material accumulated by means of the blade member (12) does not drop from the photosensitive material (2) downstream along the rotational direction of the drum (1) with respect to a position right above the drum (1).

Drawing