FIELD OF INVENTION
[0001] The invention relates generally to the field of laser printer toner cartridges and
more specifically to the field of remanufacturing such cartridges.
BACKGROUND
[0002] A laser toner cartridge contains a few significant components that directly affect
the print quality and durability over time. These significant components are all located
in the development section of the cartridge. The above mentioned components are the
photosensitive drum that is made of an electrically conducting material such as aluminum,
the developing roller, the regulating member and the primary charge roller.
[0003] During operation of a laser printer the photosensitive drum rotates as its drive
gear is rotated. Specific models of cartridges are known to have specific gear designs.
Also, such gears are typically attached to the drum by mechanical techniques, such
as described in United States Patent
7,248,841, where a mechanical crimping and coupling process was used.
[0004] The coating on the photosensitive drum typically wears off after one lifecycle of
the cartridge as a result of constant friction between the photosensitive component
and the primary charge roller, as well as friction between the developing roller and
the printed media. The amount of wear depends on multiple factors such as: type of
media printed, average coverage area of the printed documents, type of toner used,
type of documents printed (short: 1-2 pages or long: 100+ pages) type of coating etc.
It was found out that more often than not using the same photosensitive drum for another
or second lifecycle, would not produce the same print quality as the original cartridge
over the whole second lifecycle of the remanufactured cartridge. Therefore, in conventional
remanufacturing processes the photosensitive drum is treated as an exhausted component
and is replaced by a new one on all known remanufactured models of cartridges.
[0005] While the photosensitive drum can become exhausted during a single lifecycle, the
drum's drive gear typically does not become exhausted with such use, and can be re-used.
In addition, the original drum's drive gear, or specific features of a drum's drive
gear may be the subject of one or more patents, such as for example the particular
shape of a drive gear that is unique to a certain product line. In order to reuse
a cartridge component conventionally considered to be not reusable, as a precaution
in order to avoid possible patent infringement claims and as a way to reduce costs
of remanufacturing a toner cartridge, a need exists for a process and associated apparatus
by which the drive gear of original equipment toner cartridge photosensitive drums
may be reused.
SUMMARY
[0006] Responding to the aforementioned need, described herein are apparatuses and processes
for reuse of an original photosensitive drum drive gear of a laser printer toner cartridge.
The process includes removal of the original gear from the original photosensitive
drum and installation of the original gear onto a new drum cylinder. The original
gear is installed by coupling the prior art gear to the new drum preferably by surface
treating the original gear to render it more capable of holding an adhesive, and then
using adhesive to couple the original gear to a new drum. Preferably the original
drive gear from the original photosensitive drum (also referred to as a "member")
has been used at least one lifecycle, and is then installed on the new photo sensitive
member.
[0007] Because the design concepts of the original drive gear and the adherence to the original
photosensitive drum are essentially different from those of a replacement gear and
drum, the original gear is modified to improve its adhesion capability and the thus
modified original gear is installed in the drum by an adhesive processes in order
to assure durability and consistency of the product over the cartridge's lifecycle.
The preferred process for reusing a photosensitive drum drive gear includes removing
the original gear from the original photosensitive drum by using a pneumatically operated
machine that clamps the drive gear in a fixed position, and then is removed from the
drum by twisting the photosensitive cylinder out of position and off of the gear manually.
The gear removal optionally can be done automatically as well manually, or by using
an electrical clamp or a hydraulic clamp.
[0008] The original drive gear is then selectively roughened using blasting media, manual
sanding, knurling and/or creating channel grooves on the surfaces of the gear that
contacts the drum. Then the part is thoroughly cleaned using an ultrasonic bath or
manually cleaned using cleaning solvents such as iso-propanol, MEK (methyl-ethyl ketone),
acetone or mild detergents. The electrical contacts of the original gear are straightened
out in order to assure electrical continuity once the gear is pushed into a new drum.
The inside of the new drum is degreased using a solvent such as iso-propanol, and
dried. One area or more close to the end on the internal side of the new drum is preferably
laser etched, or otherwise roughened in a patch form in order to remove the anodized
layer of aluminum on the drum and thus to provide a path for electrical continuity
between the contacts on the drive gear and the drum. The roughened surface of the
drive gear is preferably primed using a diluted adhesive in order to achieve high
surface contact between the inner surface of the photosensitive drum and the outer
periphery of the drive gear shaft.
[0009] Adhesive is then applied on the internal surface of the photosensitive drum preferably
using an automatic adhesive dispenser or dispensing the adhesive manually. The adhesive
is preferably dispensed while rotating the drum. The whole adhesive application apparatus
is preferably positioned at an angle in order to allow visual inspection of the quality
of the application and the consistency of the dispensed adhesive. The drive gear is
preferably aligned on a rotary bearing in order to facilitate aiming at or placing
the contact on the area of the inside of the drum intended to provide the path for
electrical continuity, such as for example a laser etched patch on the inside of the
drum near the end where the gear is installed. Then the drive gear is pushed into
the drum preferably using a pneumatic piston in order to prevent possible contamination
of the coating that might result during a manual insertion. The electrical continuity
between the cylinder or drum and the shaft of the drive gear is then tested. At this
stage of the process, new drums having the original drive gears installed are then
preferably stacked vertically and left to cure, preferably for not less than 12 hours
at room temperature, for example at a temperature in the range of about 60-75 degrees
F, with the drive gears facing down. This orientation is preferred in order to assure
good flow of the adhesive towards a tapered area of the gear, where it is believed
that the strongest areas of bonding results.
[0010] These and other embodiments, features, aspects, and advantages of the invention will
become better understood with regard to the following description, appended claims
and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing aspects and the attendant advantages of the present invention will
become more readily appreciated by reference to the following detailed description,
when taken in conjunction with the accompanying drawings, wherein:
[0012] FIG. 1 is a perspective view of a new photosensitive member assembly with the original
drum drive gear and a new axle gear or drive gear installed;
[0013] FIG. 2 is a perspective view of a prior art drum and drive gear assembly;
[0014] FIG. 3 is a perspective view of a preferred apparatus for removing the original drum
drive gear from the original drum cylinder and with its sliding grip in the "open"
position;
[0015] FIG. 4 is a perspective view of the Figure 3 apparatus and with its sliding grip
in the "close" position;
[0016] FIG. 5 is a perspective view of the original drum drive gear assembly after treating
the adhesion surface with knurling in order to roughen the surface;
[0017] FIG. 6 is a perspective view of the original drum drive gear assembly after cutting
grooves at the adhesion surface in order to create run-out channels for the adhesive
after the assembly of the gear on the drum;
[0018] FIG. 7 is a perspective view of media blasting the original drum drive gear's adhesion
surface in order to roughen the surface prior to adhesion;
[0019] FIG. 8 is a perspective view of the adhesion surface of the drive gear after the
sand blasting process;
[0020] FIG. 9 is a perspective view of the orientation of the drive gear and the drum cylinder
before installation;
[0021] FIG. 10 is a perspective view of the orientation of the drive gear and the drum cylinder
after applying the adhesive;
[0022] FIG. 11 is a perspective view of a preferred installation apparatus prior to application
of adhesive; and,
[0023] FIG. 12 is a perspective view of the Figure 11 apparatus after application of adhesive
to the inside of the drum cylinder.
[0024] Reference symbols or names are used in the figures to indicate certain components,
aspects or features shown therein. Reference symbols common to more than one Figure
indicate like components, aspects or features shown therein.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] Hereinafter, preferred embodiments of the present invention will be described with
reference to Figures 1-12 of the drawings and with reference to Tables 1-3.
[0026] Referring to FIG. 1, a photosensitive member final assembly 20 is comprised of preferably,
a new aluminum cylinder 22 whose surface has been treated with anodizing and a photosensitive
coating on top, that is on its outer surface, and may also be referred to as a drum-cylinder.
A small, new, helical gear assembly 24 with helical teeth 26 has been installed on
the new drum-cylinder 22. Also an original helical drive gear assembly 28 with helical
teeth 30 has been removed from a depleted original drum and has been installed on
the new drum-cylinder 22 in accordance with the principles of the present inventions.
[0027] Referring to FIG. 2, a conventional drive gear assembly 28 includes a molded helical
gear 30 and helical teeth 32 as well as a metal grounding contact plate 34 in the
form of a disc. The grounding plate 34 has two opposing pairs of parallel tabs with
predetermined lengths as shown at 36, 38, 40 and 42. The parallel tabs are cut from
the periphery of the grounding plate. The tabs 36, 38, 40 and 42 have an end portion
that is slightly bent towards the driven side of the gear. The purpose of the tabs
36, 38, 40 and 42 is to create a conductive path for electrical continuity between
the drum cylinder 22 (FIG. 1) and the drum ground contact member 48. Grounding plate
34 is positioned towards the helical molded gear 30 using two holes 44, 46 that are
force-fitted on dowel plastic pins 45, 47 on the gear 30. The ground contact member
48 provides a path to ground for the drum assembly 20 (FIG. 1) through a contact on
the toner cartridge that is in turn grounded to the printing apparatus (not shown
in the drawings). The grounding member 48 is pressure fitted into the grounding plate
34 and electrically connected to the plate 34 using two leaf spring contacts 50, 52.
[0028] Adhesion surfaces 54, 54, shown on the surfaces of a prior art gear in FIG. 2, and
in a prior art gear as it is being surface treated with sand blasting, as shown for
example in FIG. 7, are the surfaces used further on in the process to adhere the original
drive gear assembly 28 to the new drum cylinder 22 as shown in FIG. 1. The surfaces
54 include the gear flange 56 and a tapered area 58, both of which are highlighted
in the FIG. 2 drawing by dashed lines. The tapered area functions were designed in
order to guide travel of the gear into the drum cylinder once it is initially inserted
into the drum cylinder. In the original drum assembly there is no adhesive involved
and the drum cylinder is crimped to the gear using two pre-cut tabs on the drum shown
at 94 in FIG 4. The tabs are bent or fit into two slots on the gear 62, one as shown
in FIG. 4, and the other slot located on the opposite side and not shown. A limiting
rail 60 (FIG. 2) is a location guide to the drive gear 28 location on the drum cylinder
22, as shown in FIG.1.
[0029] Referring to FIG. 3 a process for removing the original drum drive gear 28 from the
original drum cylinder 68 using a pneumatic clamp will be described. Pneumatic clamp
apparatus 70 is comprised of clamp housing positioning legs 74, 76; a base or housing,
one wall of which is shown at 72; a stationary grip 78; and a sliding grip 80. The
sliding grip 80 slides back and forth in the directions of the arrow 82 and has two
positions "open" and "close". Once the sliding grip 80 is in the open position the
gear is inserted into sleeve 84 in order to hold it in position. Pneumatic air cylinder
90 drives the sliding grip 80 in the directions of the arrow 82 to open and close
the clamp. The apparatus 70 also includes an air switch 92 that has two positions
"open" and "close", and a compressed air delivery hose 94. In order to operate the
apparatus to insert a cylinder, the switch 92 has to be on "open" mode. The drum is
then vertically inserted into the sleeve 84 in the direction of arrow 96.
[0030] Referring to FIG. 4, is a continuation of the removal process of the prior art drive
gear 28 from the original drum cylinder 68 by using a pneumatic clamp apparatus 70
will be described. Once the drive gear 28 is in the sleeve 84 the switch 92 is then
actuated or pushed to the "close" position (not shown) and the sliding grip 80 clamps
the gear 28 in a fixed position, with the grip 80 shown to be closed in FIG. 4 and
compared to its open position as shown in FIG. 3. Then the original drum cylinder
68 is rocked back and forth in the directions of the arrows 98, 100 in order to break
the connection between the crimping tab 94 and the slot 62 thus releasing drum cylinder
68 from gear 28. The prior art drum cylinder 68 may then be recycled or discarded,
in another manner and the gear then can be forward to be used in a new drum.
[0031] Referring to FIG. 5, a preferred surface treatment process will be described. A surface
treatment is show as having been performed on the drive gear 28 by knurling the flange
surface 56. The knurling is shown as a cross hatched surface 98, and this surface
functions to promote the adhesion of the internal surface of the new drum cylinder
22 (FIG. 1) to the flange surface 56.
[0032] Referring to FIG. 6, another preferred surface treatment is described. In the process
shown in FIG. 6 the drive gear in the location of the flange 56 was treated by cutting
grooves 100, 102 in the plastic gear in order to create run-out channels. These run-out
channels function to provide a path for the adhesive to flow as the gear 28 is pushed
into the drum cylinder 22 (FIG. 1) and as described in further detail. The groves
also function to enhance adhesion between the gear 28 and the drum cylinder 22 (FIG.
1).
[0033] Referring to FIG. 7 a preferred process of media blasting the surface of the drive
gear 28 will be described. The media blasting surface treatment is conducted at the
adhesion surface(s) shown at 54. The adhesion surface(s) 54 includes the two surfaces
of the original drive gear that were utilized to adhere or attach the gear to the
drum cylinder. Those two surfaces are flange surface 56 that function was designed
in the prior art to assure parallelism and concentricity to the drum cylinder and
the tapered surface 58 that functions was designed in the prior art to guide the gear
into the drum cylinder during installation. In accordance with the principles of the
present invention both surfaces are preferably were utilized to promote adhesion between
the drive gear and the drum cylinder. Preferably no mechanical crimping is performed
in the preferred embodiments of the present inventions.
[0034] As shown in FIG. 7 the gear is placed on an electrical rotation apparatus 103 that
has a protection housing 104, an electrical motor 106 and a gear drive collar 108.
The gear 28 is placed in the drive gear collar 108. A ground plate cover 110 is placed
on the ground plate 34 in order to protect the metal from abrasion that would otherwise
expose the plate 34 to severe corrosive attack. The assembly is then put in a conventional
media spray booth (not shown) and the drive gear 28 is then rotated at a uniform speed.
As the electrical rotation apparatus 103 turns, conventional blasting media is then
blasted using a media blasting gun 112 and blasting media 114 in a preset angle ø
to the surface of the ground 34 and at a predetermined distance from the gear 28.
The media blasting functions to roughen the flange surface 56 and the tapered surface
58. This process enhances adhesion between the drive gear 28 and the drum cylinder
22 as shown in FIG. 1.
[0035] Referring to FIG. 8 the drive gear 28 is shown after the adhesion surfaces 56 and
58 have been media blasted and roughened in comparison to the original smooth appearance
as shown in FIG. 2.
[0036] Referring to FIG. 9 the orientation of the drive gear 28 to the drum cylinder 22
immediately before the gear is pushed into the drum is shown. The gear is positioned
adjacent the end 118 of the drum 22. Also, as shown the tabs 36, 38 are positioned
to be in-line with the laser patch 114 and this orientation is most preferable because
it facilitates the subsequent adhesion process.
[0037] Referring to FIG. 10 the orientation of the drive gear 28 in relation to the drum
cylinder 22 immediately after applying adhesive bead 116 is shown. The bead 116 is
applied on the inside of the drum 22 as close as possible to the cylinder edge 118,
and around that part of the inner periphery of the drum that has had its anodized
surface removed by the laser treatment. In other words, the laser patch 116 is preferably
kept free of adhesive. The gear is then pushed into the drum 22 in the direction of
the arrows 111, 113.
[0038] Referring to FIG. 11 a gear installation apparatus 120 is shown prior to application
of the adhesive on the inside of the drum 22. The installation apparatus 120 is comprised
of a plate 122; a sliding gear cradle 134; a rotary gear insert 136; an air cylinder
130; slides 132, 132; a felt covered v-block 146; an alignment pin 142; a drive gear
box and its external gear that engages with the axle gear 24, shown at 144; momentary
pneumatic switch 140; an electric motor 124; and electric motor activating switch
126;, a power cord 128; and, angling legs 148, 150.
[0039] Referring to FIGS. 11-12 a preferred process of installing the drive gear 28 onto
the drum cylinder 22 is described. Drum cylinder 22 is affixed into apparatus 120
by engaging or placing gear 24 over pin 142 and then lowering the drum 22 down to
be in contact with and rest on the felt covered v-block 146. Next switch 126 is actuated
and the drum then rotates a complete 360 degrees. During that rotation operation an
adhesive bead 154 is applied to the inside of the drum 22. A dual component adhesive
cartridge applicator 152 is used to apply the adhesive to the inside surface of drum
22, and the adhesive is applied, preferably, as close as possible to the edge of the
cylinder 118 and around the entire inner periphery, but excluding the area of the
drum that has the laser etch patch 114.
[0040] Preferably after being primed, and as described below, the drive gear 28 is then
positioned onto the rotary insert 136. The gear 28 is then aligned with the drum 22
by manually rotating it so that tabs 36, 38 are aligned, preferably by visual inspection,
with laser etched patch 114. Pneumatic switch 140 is then depressed to activate air
cylinder 130, which then causes cradle 134 to move in the direction of arrow 138 and
insert the gear into to drum at its end 118. Pneumatic momentary switch 140 is then
released, causing air cylinder 130 to move cradle 134 in the direction of the arrow
139, that is, to return the cradle 134 back to its home position. An electrical continuity
test is then conducted, preferably by contact ground member 48A, shown in FIG. 2,
and an uncoated area in the drum cylinder 22 as the contact points.
[0041] In accordance with embodiments of the present invention the process of removing the
original drive gear from a used photosensitive member and installing the used, original
drive gear on a new photosensitive member will be described. Removing the prior art
gear from the prior art drum cylinder is preferably accomplished by using a pneumatic
clamp that holds the drive gear with the assistance of a pneumatic clamp apparatus
70, as shown in FIG. 3, and the gear is removed by twisting the drum's cylinder out
of the gear and then releasing the gear by moving it back and forth, shown for example
in FIG 4 by the arrows 98, 100. This operation can be done by other means of clamping,
such as for example hydraulic, electrical or manual means, any and all of which are
considered to be equivalent, so long as the gear and the drum are separated without
damage to the gear. The drum can be twisted out manually or pulled out using a hydraulic,
pneumatic or mechanical means. In the conventional, prior art, original equipment,
the drive gear is connected to the original drum cylinder by mechanical means such
as crimping that uses two tabs of the pre-cut aluminum cylinder 94, as shown in FIG.
4. The tabs are pushed into two slots in the gear assembly, shown at 62 in Fig. 4.
In accordance with the principles of the current invention, however, it is preferable
that no mechanical clamping is performed. Rather and instead adhesion is used to connect
and attach the drive gear to the drum cylinder.
[0042] In order to make sure that the presently described embodiments function to attach
an original gear to a new drum as well as the original gear was attached to the original
drum a series of torque measurements were taken. Those measurements were taken with
a JETCO brand torque wrench, 0-100 ft. lb range. In regard to the prior art design,
i.e., the original gear as attached to the original drum, the gear failed at 5 ft.
lb. In other words at an application of 5 ft. lbs. of torque the gear would break
loose from the drum. This value is referred to as the torque failure value, and was
used as a benchmark or standard for determining the attachment or adhesion strength
of various embodiments as described herein. In other words, in order for a process
of attachment of an original gear to a new drum to be considered useful, it must meet
or exceed the torque failure value of the original equipment drum and gear assembly.
Surface Treatment or Preparation of the Gear
[0043] As described herein four surface preparation methods are preferred: (a) knurling;
(b) grooving; (c) media blasting; and (d) primer. The four different techniques were
experimented with in order to generate a larger and/or better surface for adhesion,
and thus increase the strength of the adhesion, gripping power or mechanical grip
of the adhesive to the surface of the gear. It is believed that in the prior art designs
only mechanical crimping was employed to attach the gear to the drum, with no adhesive
used, and that no consideration was given to the adhesion affinity of the surfaces
of the gear and the drum cylinder with respect to each other. The prior art gears
intended to be used in the present inventions were made of nylon polymer. As is well
known, it is extremely hard to make another structure or item adhere to a component
made of nylon polymer, due to the very nature of the nylon polymer.
[0044] In order to enable adhesion, it was discovered that surface treatment was needed,
and the knurling, grooving and/or media blasting techniques proved to be useful. Furthermore,
it has been discovered that the use of all four methods or techniques produces superior
adhesion properties after 24 hours from the time of application of the adhesive. It
has also been discovered that if used alone, the knurling and grooving processes do
not produce such superior results. Rather, for gear-drum assemblies made with only
a knurling or grooving surface treatment, a consistent decline in adhesion strength
over time, in aggressive environments, such as high humidity and extreme temperature
differences, has been found to result.
It has also been discovered that the most preferable or most desirable surface treatment
is media blasting using Aluminum-Oxide grit #220 as a blasting media. It is believed
that other types of media and grit can be used to achieve a useful result. The blasting
pressure was 40-70 psi and the gears were blasted using a media blasting gun commercially
available from CYCLONE. As seen in FIG. 7 the grounding plate 34 had to be used during
the media blasting process, in order to prevent the media from damaging the protective
coating on the surface of the phosphorus bronze plate. Failure to protect the coating
with the grounding plate would result in severe corrosion that will be developed in
a matter of hours. Such corrosion can lead to electrical discontinuity between the
ground member 48, shown in FIG. 2, and the drum-cylinder 22, as shown in FIG. 1, and
could also lead to possible failure of the photosensitive member, and thus failure
of the cartridge. The media blasting process was done using an electrical motor assembly
or apparatus as shown in FIG. 7. The gear was rotated 2-4 complete rounds at a slow
speed of 8-12 revolutions per minute, as the blasting gun was held at a distance of
about 1-3 inches from the surface, and at a 25-75 degree angle Ø from the surface
of the flange 56, also as shown in FIG. 7. The prior art gear was media blasted in
a conventional blasting chamber made by UNIVERSAL EQUIPMENT MANUFACTURING CO. The
media was reused in a conventional fashion. Other blasting systems or chambers can
be used, for example gravity fed blasting guns or other techniques, so long as they
provide for the end result of a gear surface preparation sufficient to yield adhesion
of the gear to the drum at above the torque failure value.
Cleaning of the Surface Treated Gear
[0045] Preferably the surface treated gear is then cleaned in order to remove all grease
and contamination residues as well as media blasting residues. Cleaning preferably
was achieved by using air blasting to remove the bigger particles and then by submerging
the surface treated drive gears in a conventional ultrasonic bath. Preferably iso-propanol
is used in the bath as a degreaser, and the ultrasonic bath is lasts for at least
1 minute. Preferably the cleaned gears are then dried in ambient air for at least
5 minutes. Other techniques can be used to clean the drive gears such as manual brushing,
wiping, flushing or dipping numerous times, so long as the end result is a surface
treated gear that will adhere to the drum at greater than the torque failure value.
Straightening Contact Tabs
[0046] The contact tabs of the original gear are also straightened, preferably after the
gear has been surface treated and cleaned. In the preferred embodiments described
above, straightening of the contact tabs 36, 38, 40 and 42 was done using pointed
pliers. The tabs on the ground plate 34, shown in FIG. 2, come bent and once taken
out of the original gear tend to deform. Unless straightened, the typical deformation
of the original gears might cause electrical discontinuity. Therefore, the tabs are
preferably straightened in order to facilitate electrical continuity between the tabs
and the internal surface of the drum cylinder when the original drive gear is installed
on a new drum, as describe herein.
Oxidation Removal From the New Drum
[0047] As is well known the typical, original photosensitive drum is manufactured with a
technique that does not involve anodizing of the aluminum cylinder. As described above,
however, the preferred embodiments of the current inventions relate to a new drum
cylinder that is manufactured using an anodizing process in order to adhere the photo
sensitive coating to the aluminum cylinder surface. The anodizing process is one in
which the electrical conductivity property of the anodized metal is greatly reduced.
Thus, in order to provide for electrical continuity in a drum-gear assembly having
an anodized drum, it is preferred that part of the anodized area of the drum is removed
and a conductive path be established. In the event a new drum to be used with an original
gear and in accordance with the principles of the present inventions is not anodized,
then this part of the process can be skipped.
[0048] Preferably a laser etching technique is used to etch a rectangular patch close to
the end 118 of the cylinder, as shown at patch 114 in FIG. 9. This patch is made in
order to provide a conductive path for electrical continuity between the ground plate
34 on the drive gear 28, as shown in FIG. 2, and the drum. The laser etching removes
the insulating, anodizing layer on the inner surface of the aluminum cylinder and
exposes the conductive aluminum. An equivalent result can be achieved with other processes,
such as with mechanical means, sand paper, etc. The laser etch process is preferred
due to its relatively high speed and cleanliness. Moreover, any mechanical removal
process might cause dust residues that can contaminate the surface of the photosensitive
coating and would require additional labor to clean.
Adhesive Application
[0049] As described above the original gear, preferably processed as describe above, is
adhesively attached to a new drum. In this regard three main groups of adhesives were
tested for their adhesion properties in this application. Those three groups were:
cyano-acrylates; acrylics; and, epoxies. Samples of these adhesives were applied on
the internal surface of a drum cylinder. Because the gear is very close in dimensions
to the inner orifice of the cylinder, i.e., a very tight fit, whenever adhesive is
applied to the gear's surface, the adhesive will come out when the gear is pushed
into the drum. This external adhesive then has the potential to might cause contamination
of the outer surface of the drum. In order to avoid or minimize this risk, it is preferable
that adhesive be applied on the inner surface of the cylinder. Thus, once the drive
gear is installed the adhesive residues are pushed inside the cylinder.
[0050] Shown below in Tables 1-3 are results of adhesive testing with a variety of adhesives,
surface preparations and test conditions. Adhesive application was tested first without
surface treatment to the gear. The first adhesive candidates were in the cyano-acrylate
family, because of the ease of use and the low cost. As can be seen in Table 1, two
brands of cyano-acrylates were used. The first was Permabond 910 available from Permabond
Engineering Adhesives. This is a 100% methyl cyano-acrylate, single part, low viscosity,
fast cure cyano-acrylate. The second was Loctite 411 brand adhesive made by Henkel
Loctite Corporation. This is also a low viscosity, fast cure cyanoacrylate, specifically,
a single part, ethyl cyanoacrylate.
[0051] In comparing the adhesion strength, as can be seen from samples 1-6 on Table 1, where
no surface treatment was used, the Loctite 411 brand adhesive yields higher adhesion
strength with an average failure torque value for the Permabond 910 brand adhesive
of 16 and an average failure value of 19.3 for the Loctite 411 brand adhesive. Moreover,
the Loctite 411 adhesive is lower in viscosity and easier to apply than the Permabond
910 adhesive.
[0052] Referring to sample or test number 7, when the gear was surface treated with sand
blasting and the ethyl cyano-acrylate adhesive was used, the torque failure value
was 40, which represents a significant increase in adhesion strength. Referring to
samples 8-9, a two-part epoxy adhesive was used. Specifically, Scotch-Weld DP190 brand
epoxy/amine adhesive, available from 3M Company was used. The DP190 brand epoxy adhesive
had an average failure torque of 14, when no surface treatment was used. When a "primer
only" surface treatment was used, the DP190 brand adhesive yielded failure torques
of 20, referring to samples 10-11. When the gear was surface treated with sand blasting
the DP190 adhesive yielded a failure torque of 15, as shown in sample 12, which compared
unfavorably to a relatively high value of 40 for sample 7, in which Loctite 411 adhesive
was used with a gear that had been surface treated with sand blasting. Referring to
samples 12-13, the DP190 had relatively low failure values when surface treated with
sand blasting and sand blasting plus primer, respectively. Referring to sample 14
a two-part acrylic adhesive was used. Specifically, 3M Scotch-Weld, DP-810 brand acrylic
adhesive was used. As shown in sample 14, the DP-810 brand adhesive had a very low
failure torque of 5, when tested without surface treatment, much lower than either
the Permabond 910 or Loctite 411 adhesives when used without surface treatment.
[0053] The Table 1 torque tests also showed that in most cases the rupture surface was the
plastic of the gear itself, rather than at the adhesion. This means that the gear
broke before the adhesion surface was disconnected. As shown in Table 1, in all tests
in which a cyano-acrylate adhesive was used, it was the gear itself that failed; not
the adhesion. When the epoxy or acrylic adhesives were used, however, in only one
instance did the failure result in the gear. All other failures (samples 8-12 and
14) were in the adhesion itself. The results of the tests as shown in Table 1 suggested
that the cyano-acrylate adhesives were good candidates, with the Loctite 411 brand
adhesive holding the most promise.
[0054] Referring to Table 2, new test samples 15-17 were prepared then tested using Loctite
411 adhesive in a thermal cycling chamber. Specifically, a TEST EQUITY 1000 SERIES
brand temperature chamber was used, with the samples tested for 10 days with the following
temperature cycle that repeated itself during the whole 10 days: (a) 20 minutes ramp
up from 25-55 degrees C; (b) 90 minutes at constant 55 degrees C; (c) 30 minute ramp
down from 55 degrees C to 10 degrees C; (d) 90 minutes at -10 degrees C; (e) 20 minute
ramp up -10 degrees C to 25 degrees C. As can be seen from the results on samples
15-17, the adhesion strength essentially completely failed after the temperature cycle
testing. It was observed by visual inspection that in every one of samples 15-17 the
adhesive residues were held to the aluminum and none were held to the gear. As a result,
it was believed that cyano-acrylates are too brittle for this application. Aluminum
and the nylon have much different thermal expansion coefficients, and thus the shear
forces on the adhesion surface are believed to be too strong to maintain a bond after
temperature cycling of the type exemplified above. In order to overcome this problem,
it was believed that surface treatment applied to the gear might reduce or eliminate
this problem.
[0055] Four types of surface treatment were chosen to be tested: knurling, grooving, sand
blasting and primer. All four surface treatments were thermal cycle tested against
each other in the thermal cycling chamber. As can be seen from tests 18-20 in Table
2, the failure values for knurling, grooving and sand blasting after the thermal cycling
were still significantly lower in comparison to the corresponding values obtained
the day after the application of the adhesive, as shown on Table 1, samples 4-6. These
results prompted use of primer and sand blasting. Specifically, Loctite 770 brand
plastic primer was applied on the gear prior to applying the adhesive. Loctite 770
brand plastic primer is a cyano-acrylate, specifically, an aliphatic amine in a n-Heptane
solution. The results are shown samples 21-23 on Table 2. The deterioration of the
adhesion strength after the thermal cycle test was also shown to be significant, with
the rupture taking place at relatively low values and at the adhesion.
[0056] Next, a flexible adhesive system was chosen in an attempt to compensate for the difference
in thermal expansion coefficients between the nylon and the aluminum of the gear and
drum, respectively. The epoxy adhesive that was tested was the flexible, dual component
system DP190 from 3M and as an acrylic system the dual component DP-810 adhesive system
from 3M was tested. As can be seen from sample 14 in Table 1, use of the DP-810 adhesive
resulted in very low adhesion strength compared to the cyano-acrylates and epoxies.
However, the DP190 flexible epoxy system resulted in much better performance than
the acrylic system but still exhibited significantly lower failure values than did
the cyano-acrylates system in failure testing conducted at time "Zero", i.e., one
day after the adhesive was applied, and as reported in Table 1.
[0057] Also, in order to promote the adhesion a different primer was added to the system
as a surface treatment. The primer was DP190 adhesive diluted in iso-propanol at a
1:10 ratio. This high dilution ratio yielded a very low viscosity fluid and enabled
application of the primer to the adhesion surface of the gear without concern that
it would come out and contaminate the drum once the gear was inserted into the drum
cylinder. As can be seen from samples 10-11 in comparison to samples 8-9 in Table
1, the presence of the DP190 primer promoted the adhesion significantly in comparison
to the tests with the same adhesive but without a surface treatment. The DP190 adhesive
and the DP190 adhesive-primer surface treatment system was then used and tested in
the thermal cycles testing and using the same chamber and test procedure as referred
to above. The results are reported in samples 24-27 in Table 2. Application of primer
on the surface of the gear was shown to promote adhesion, but significant deterioration
in adhesion strength remained after thermal cycling with and without primer.
[0058] A combination of media blasting and primer as a surface treatment was used and tested,
with the results reported as sample 13 in Table 1. In this sample the gear plastic
failed rather than the adhesion surface, and the bond strength was significantly higher
than the samples that used DP190 adhesive and only one of the two surface treatments.
The gear-drum assembly having the combination of primer and sand blasting as a surface
treatment was then tested in the thermal cycling chamber under the test procedure
referred to above. The results are reported in samples 29-34 on Table 2. It can be
seen that not only did the bond strength not deteriorate over the time of the test
period, but became stronger. As a result, the combination of both sand blasting and
priming of the gear's surface was chosen as the most preferred surface treatment and
this surface treatment in combination with the DP190 adhesive was chosen as the most
preferred technique or method for adhesively attaching a gear to the drum.
[0059] In order to further evaluate bond strength in aggressive, corrosive conditions over
time, sample gear-drum assemblies were tested in a walk-in temperature humidity chamber
made by WATLOW SERIES F4S/D. This testing was conducted at 80%rH and 80 degrees F
for 14 days. The results are reported as samples 35-40 in Table 3. As shown in Table
3, bond strength greatly varies in these samples, but is still significantly higher
than 5 ft. lb. standard that was determined by measuring the failure torque for the
mechanical coupling of the original gear-drum assembly. From Table 3 it can be seen
that the interface of rupture is affected by humidity as well as by thermal cycling
and that most of the failures took place at the adhesion (samples 35-40, 43) rather
than in the gear plastic (samples 41-42). Also, it may be seen from samples 41-43,
the bond strength is very high and the interface of rupture is within the plastic
(samples 41-41) or within the adhesion (sample 43), even when using only primer. As
a result of the testing reported in Table 3, it is believed that the presence of humidity
is not the main cause or even a significant cause of deterioration in bond strength.
Even if humidity is significant in some instances, it appears that the flexible epoxy
system is superior in adhesion strength to the cyano-acrylates system when performance
over time is considered. Referring to sample 28, this sample shows that sand blasting
alone as a surface treatment is not enough to yield a successful adhesion over time
and that use of the DP190 adhesive was needed to yield successful adhesion over time.
[0060] As understood from the above reported results, cyano-acrylates have relatively low
torque failure values in temperature cycling tests and the flexible epoxy adhesive,
DP190 brand adhesive, performs the best. Even though cyano-acrylate adhesives perform
very well, at start, that is soon after curing, torque failure value decreases significantly
after thermal cycling. As a result of thermal cycle testing the most preferred process
for attaching the gear to the drum includes surface treating the gear that includes
a primer prior to applying adhesive. The preferred primer is DP190 adhesive-primer,
available from 3M, and this is used when diluted in iso-propanol at a ratio of 1:10.
The primer is preferably applied using a swab on the bond area and dried in ambient
air for no less than 5 minutes. The dilution 1:10 was derived from the need to keep
the primer thickness as thin as possible to prevent run-out of material as the gear
is pushed inside the drum cylinder, but nevertheless to provide a useful surface treatment.
[0061] Application of the adhesives as reported in Tables 1-3 was conducted with the gear
assembly apparatus or machine as illustrated in FIGS. 11-12. Also, the two-component
adhesives were applied using a dual component adhesive gun dispenser as referred to
above. The cyanoacrylate, mono-component adhesives were dispensed directly from the
tubes in which they were packaged. The dual cartridge was connected to a static mixer.
Both the dispensing gun and the static mixer were made by and available from 3M Company.
They are standard for dual component cartridge applications. The test samples were
also tested for electrical continuity between the drum cylinder and the drive gear
ground member using continuity tester/buzzer available from ILM TOOL INC. In this
testing the contact on the drum side is pushed with sufficient force pass through
the insulating anodizing layer and to touch the conductive aluminum. The gear-drum
assemblies were cured by stacking the drums vertically with the drive gear facing
down in order to allow the adhesive to flow during the curing time into the space
created between the tapered surface on the drive gear, shown at 58 in FIG. 2, and
the drum cylinder. This was to increase the area of the adhered surface, and thus
increase the adhesion strength of the gear to the drum. The drums were cured for not
less than 24 hours prior to assembly into a cartridge.
[0062] Although specific embodiments of the invention have been described, various modifications,
alterations, alternative constructions, and equivalents are also encompassed within
the scope of the invention.
[0063] The specification and drawings are, accordingly, to be regarded in an illustrative
rather than a restrictive sense. It will, however, be evident that additions, subtractions,
deletions, and other modifications and changes may be made thereunto without departing
from the broader spirit and scope of the invention as set forth in the claims.
Table -1 Room temperature (reference) testing (75 degrees F and 30%rH)
Test Number |
Adhesive |
Adhesive Group |
Drive gear Surface Treatment |
Test type |
Torque (Ft-Pound) |
Interface of Rupture* |
1 |
Permabond 910 |
Cyano-Acrylate |
None |
Torque |
18 |
Plastic |
2 |
Permabond 910 |
Cyano-Acrylate |
None |
Torque |
20 |
Plastic |
3 |
Permabond 910 |
Cyano-Acrylate |
None |
Torque |
10 |
Plastic |
4 |
Loctite 411 |
Cyano-Acrylate |
None |
Torque |
18 |
Plastic |
5 |
Loctite 411 |
Cyano-Acrylate |
None |
Torque |
30 |
Plastic |
6 |
Loctite 411 |
Cyano-Acrylate |
None |
Torque |
10 |
Plastic |
7 |
Loctite 411 |
Cyano-Acrylate |
Sand Blasting |
Torque |
40 |
Plastic |
8 |
DP190 |
Epoxy |
None |
Torque |
15 |
Adhesion |
9 |
DP190 |
Epoxy |
None |
Torque |
13 |
Adhesion |
10 |
DP190 |
Epoxy |
Primer only |
Torque |
20 |
Adhesion |
11 |
DP190 |
Epoxy |
Primer only |
Torque |
20 |
Adhesion |
12 |
DP190 |
Epoxy |
Sand Blasting |
Torque |
15 |
Adhesion |
13 |
DP190 |
Epoxy |
Sand Blasting + Primer |
Torque |
30 |
Plastic |
14 |
DP- 810 |
Acrylic |
None |
Torque |
5 |
Adhesion |
* Interface of Rupture: The term "Plastic" means that the plastic of the drive gear
broke before the adhesive failed. The term "Adhesion" means the adhesive separated
from the gear and/or the drum before either of the substrates failed. |
Table 2 - Test results after Temperature cycles for 10 days
Test Number |
Adhesive |
Surface Treatment |
Test type |
Torque (Ft-pound) |
Interface of Rupture |
15 |
Loctite 411 |
None |
Torque |
0 |
Adhesion |
16 |
Loctite 411 |
None |
Torque |
2 |
Adhesion |
17 |
Loctite 411 |
None |
Torque |
1 |
Adhesion |
18 |
Loctite 411 |
Knurling |
Torque |
5 |
Adhesion |
19 |
Loctite 411 |
Grooving |
Torque |
7 |
Adhesion |
20 |
Loctite |
Sand Blasting |
Torque |
3 |
Adhesion |
21 |
Loctite 411 |
Sand + 770 Primer |
Torque |
0 |
Adhesion |
22 |
Loctite 411 |
Sand + 770 Primer |
Torque |
17 |
Adhesion |
23 |
Loctite 411 |
Sand + 770 Primer |
Torque |
10 |
Adhesion |
24 |
DP190 |
None |
Torque |
7 |
Adhesion |
25 |
DP190 |
Primer |
Torque |
10 |
Adhesion |
26 |
DP190 |
Primer |
Torque |
9 |
Adhesion |
27 |
DP190 |
Primer |
Torque |
12 |
Adhesion |
28 |
DP190 |
Sand Blasting |
Torque |
10 |
Adhesion |
29 |
DP190 |
Sand Blasting + Primer |
Torque |
55 |
Plastic |
30 |
DP190 |
Sand Blasting + Primer |
Torque |
45 |
Plastic |
31 |
DP190 |
Sand Blasting + Primer |
Torque |
65 |
Plastic |
32 |
DP190 |
Sand Blasting + Primer |
Torque |
60 |
Adhesion |
33 |
DP190 |
Sand Blasting + Primer |
Torque |
60 |
Plastic |
34 |
DP190 |
Sand Blasting + Primer |
Torque |
50 |
Adhesion |

[0064] The present invention further includes the following embodiments:
- 1. A method for installing an original drive gear of an original photosensitive drum
for a laser printer toner cartridge on a new photosensitive drum for a laser printer
toner cartridge comprising:
providing an original assembly that includes the original photosensitive drum and
the original drive gear;
providing a new photosensitive drum, the new photosensitive drum being in the form
of a cylinder having a new drum inner periphery and a new drum first end;
the original photosensitive drum being in the form of a cylinder having an inner periphery
and an original drum first end;
the original drive gear having a contact surface that is in mechanical contact with
the original photosensitive drum inner periphery, the contact surface is attached
to the inner periphery at the original photosensitive drum first end and the contact
surface has a predetermined adhesive capability;
removing the original drive gear from the original photosensitive drum and exposing
the original drive gear contact surface;
treating the original drive gear contact surface to increase its adhesive capability
and to form a surface treated original drive gear;
placing an epoxy/amine adhesive on a portion of the new drum inner periphery at the
new drum first end;
inserting the surface treated original drive gear into the new drum first end; and,
curing the adhesive.
- 2. The method of embodiment 1, wherein said new photosensitive drum is made of aluminum.
- 3. The method of embodiment 1, wherein said new photosensitive drum is made of aluminum
and has an anodized surface.
- 4. The method of embodiment 1, wherein treating the original drive gear contact surface
includes knurling the contact surface.
- 5. The method of embodiment 1, wherein treating the original drive gear contact surface
includes grooving the contact surface.
- 6. The method of embodiment 1, wherein treating the original drive gear contact surface
includes blasting with an abrasive media.
- 7. The method of embodiment 1, further including applying a primer on the contact
surface prior to placing the adhesive on the contact surface.
- 8. The method of embodiment 1, wherein treating the original gear contact surface
includes blasting the contact surface with an abrasive media and thereafter applying
a primer on the contact surface.
- 9. The method of embodiment 8, wherein the primer includes DP 190 brand epoxy/amine.
- 10. The method of embodiment 1, wherein the adhesive is an epoxy/amine adhesive.
- 11. The method of embodiment 1, wherein the adhesive is DP190 brand epoxy/amine adhesive.
- 12. The method of embodiment 3 further includes removing a portion of the anodized
surface of the new photosensitive drum to form an electrically conductive surface.
- 13. The method of embodiment 12 wherein the portion of new drum inner periphery on
which the adhesive is applied substantially excludes the electrically conductive surface.
- 14. A laser printer toner cartridge photosensitive drum and drive gear assembly comprising:
a new photosensitive drum being in the form of a cylinder,
having a new drum inner periphery and having a new drum first end;
an original drive gear having a contact surface;
an organic adhesive positioned between the original drive gear contact surface and
the new photosensitive drum inner periphery, whereby
the original drive gear is adhered to the new drum inner periphery with the organic
adhesive at the new drum first end and is adhered to the new drum with an adhesive
strength having a torque failure value of at least 5 ft. lbs.
- 15. The assembly of embodiment 14 wherein the organic adhesive is an epoxy/amine adhesive.
- 16. The assembly of embodiment 14 wherein the organic adhesive is DP190 brand epoxy/amine
adhesive.
- 17. The assembly of embodiment 14 wherein the original drive gear contact surface
was sand blasted.
- 18. The assembly of embodiment 14 wherein the original gear contact surface has been
coated with a primer comprising an epoxy/amine.
- 19. The assembly of embodiment 14 wherein the original gear contact surface has been
sand blasted and coated with a primer comprising an epoxy/amine.
- 20. A method for installing an original drive gear of an original photosensitive drum
for a laser printer toner cartridge on a new photosensitive drum for a laser printer
toner cartridge comprising:
providing an original assembly that includes the original photosensitive drum and
the original drive gear;
providing a new photosensitive drum made of aluminum, having an anodized aluminum
layer on its surface, being in the form of a cylinder having a new drum inner periphery
and having a new drum first end;
the original photosensitive drum being in the form of a cylinder having an inner periphery
and an original drum first end;
the original drive gear having a contact surface that is in mechanical contact with
the original photosensitive drum inner periphery, the contact surface is attached
to the original drum inner periphery at the original photosensitive drum first end
and the contact surface has a predetermined adhesive capability;
removing the original drive gear from the original photosensitive drum and exposing
the original drive gear contact surface;
treating the original drive gear contact surface by sand blasting and thereafter coating
the contact surface with a solution of DP190 brand epoxy/amine adhesive and iso-propanol
in the ratio of about 1:10 to form a surface treated original drive gear;
removing a portion of the anodized surface from the inner periphery of the new photosensitive
drum near the new photosensitive drum first end to form an anodized-free patch area;
placing a predetermined amount of DP190 brand epoxy/amine adhesive on a portion of
the new drum inner periphery at the new drum first end having an anodized layer and
maintaining free of the DP190 brand epoxy/amine adhesive a substantial portion of
the anodized-free patch area;
inserting the surface treated original drive gear into the new drum first end; and,
curing the adhesive for at least 12 hours at a temperature in the range of about 60-75
degrees F.