JPH0250168A - Image producing device - Google Patents

Abstract

PURPOSE:To facilitate attaching and detaching and to accurately and easily keep positioning precision by making a transfer charger unit and a resist roller unit get in and out integrally with an exchange unit while mutually keeping the positional relation with a device main body. CONSTITUTION:The resist roller unit 23 is attachably and detachably mounted in an image producing case 2. In a state where the image producing case 2 is inserted into a printer main body 1, an image producing unit consisting of a photosensitive unit 4, a developing unit 5, a cleaning unit 6 and a toner cartridge 7, etc., is mounted by mutually keeping the proper positional relation so that recording actions by an electrophotographic system are accurately performed. The image producing unit is positioned so that it may keep the proper positional relation with an optical writing unit 21, an electrostatic charger 22 and the resist roller unit 23, etc., which are provided on the printer main body 1 side. Thus, attaching to and detaching from the device main body can be facilitated and the positioning precision can be accurately and easily kept.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image forming device for equipment having a recording section using an electrophotographic method, such as a non-impact printer or a copying machine.
In particular, a plurality of image forming units such as a photoconductor unit, a developing unit, and a image forming unit are configured as a replaceable unit, and an image forming case that is detachable from the main body, a transfer charger unit that is detachable, a registration roller unit, and a paper feeder. This is related to the unit.

Another aspect of the present invention relates to a pre-transfer guide plate that guides recording paper to a photosensitive drum and a transfer charger unit.

(Prior art) Printers and copiers using electrophotography have almost the same processes except for the optical system, and require toner replenishment and replacement of photoreceptors, developing, cleaning, chargers, etc. It has the necessary units.

Nowadays, not only toner replenishment but also photoconductor unit,
Machines have been commercialized in which even the cleaning unit can be replaced by the user. Particularly in the case of printers, there is a strong demand for user maintenance, and it is becoming a necessary condition that each replaceable unit can be easily replaced by the user.

In an example of a conventional device of this type, a plurality of image forming units such as a photoconductor unit, a developing unit, and a cleaning unit are integrated, and after a certain period of time, these integrated units are replaced when replaced. I try to replace them as a whole. The lifespan and wear and tear of each unit vary depending on its characteristics and usage conditions, so even if a certain unit reaches the end of its lifespan and needs to be replaced, other units may still be fully usable. However, in such an integrated device, since the unit must be replaced at the same time as the unit that needs to be replaced sooner, the cost of parts for each replacement is high, and running costs are inevitably high. The disadvantage was that it imposed a heavy burden on

In addition, in order to eliminate the drawbacks of integrated units, some machines are designed to have separate replacement cycles for each unit, such as the cleaning unit, developing unit, and photoconductor unit, and to replace each unit individually. has been made into

The methods of exchange can be roughly divided into two types.

One method is to pull out each unit individually from one machine body and replace it. This method requires a mechanism for pulling out each unit, and the positions between each unit must be accurately positioned. Not only is it difficult to replace the unit because it is located in a narrow space, but when you take out the unit to be replaced, you may damage other units that are not due for replacement, or the toner may spill and stain the inside. The drawback was that it was easy to do.

Another method is to use each unit as an imaging unit.
This is a method in which the entire unit is pulled out from the machine body, and individual units are replaced from the pulled out unit. In this method, each unit is positioned with the precision necessary for operation within the main body, and then pulled out as it is, making it difficult to remove the unit and also making it easy for toner to spill and damage the photoreceptor. There were drawbacks.

Additionally, the transfer charger and registration roller were installed inside the machine body to facilitate handling of paper jams. Therefore, conventionally, there has been no system in which the image forming case, transfer charger, registration roller, etc. are integrated into a unit, and the parts can be pulled out from the main body of the machine and replaced when necessary.

Next, the arrangement of the pre-transfer guide plate that guides the recording paper to the photosensitive drum and the transfer charger unit will be explained with reference to FIG. 14. The positional relationship between the pre-transfer upper guide plate 78A and the pre-transfer lower guide plate 78B is with respect to a tangent 90 on the photoreceptor drum 4A that intersects the line connecting the center 4a of the photoreceptor drum 4A and the transfer charger wire 8A. Each tip 78a of the pre-transfer upper guide plate 78A and the pre-transfer lower guide plate 78B
,,78b1 is on top.

There were many things that were different, such as being at the bottom.

The tangent line 90 can be regarded as the course of the recording paper 91. Therefore, the tip 7 of the lower pre-transfer guide plate 78B
8b is above this tangent line 90 in the drawing, when the recording paper 91 comes off as shown in FIG. , the recording paper 91 is bent away from the photoreceptor drum 4A due to a force that tends to return the deflection to its original state. Therefore,
The trailing edge of the recording paper sometimes caused transfer gaps.

Further, contrary to the above, the tip portion 7 of the pre-transfer upper guide plate 78A
In the case of FIG. 15 in which the workpiece 8a is below the tangent line 90, when the trailing edge of the recording paper 91 passes through the pre-transfer upper guide plate 78A ((1) in the same figure), the recording paper 91 is still bent. Because there is
The recording paper tries to go straight in the tangential direction of 90.

When the recording paper comes off as shown in (2) in the same figure, the recording paper is deflected, and the vibration that returns to its original state causes abnormal images such as misaligned transfer and missing transfer at the trailing edge.

Next, as shown in FIG. 16, the pre-transfer upper guide plate 78A
The distance between the rear end 78a2 on the side of the registration rollers and the tangent line 92 of the pair of registration rollers 23A and 23B is 1, for example, when the diameter of the registration rollers is about φ20m, the distance is about 3m, and the distance between the upper and lower guide plates and the pair of registration rollers before transfer is set to 1. This prevents recording paper from getting in between.

Further, the tangent line 92 of the pair of registration rollers and the pre-transfer upper and lower guide plates are arranged with the tangent line 92 as a boundary so that neither the upper nor the lower guide plate overlaps, and from their front end portions 78a, 78b to the rear end portion 78a.
, , 78b are gradually opened so that the recording paper can smoothly advance from the pair of registration rollers to the photoreceptor drum 4A without putting an extra load on the recording paper.

However, when photoreceptor drums and the like are downsized, the above-mentioned dimensions and arrangement relationships are not maintained, and the angle at which the recording paper enters the photoreceptor drum 4A becomes steeper, resulting in poor adhesion.

The deflection of the recording paper increases. As a result, when the trailing edge of the recording paper passes through the registration rollers, a force acts to restore the flexure of the recording paper, and the trailing edge of the recording paper moves to the pre-transfer upper guide plate 7.
It fluctuates until it hits 8A and is regulated. At this time, the contact between the recording paper in the transfer area and the photosensitive drum becomes unstable, and an abnormal image due to transfer deviation occurs.

In addition, the paper feed system in conventional electrophotographic image forming devices such as printers and copiers has a structure that is assembled to the side plate of the main body of the device, and the parts that make up the paper feed system are assembled in the order and direction of screwing. There were various problems, and the assembly was poor. Therefore, if one part is worn out or damaged, there is a drawback that in order to remove the part, it is impossible to replace or repair the part without removing other parts assembled to the side plate of the main body of the device. .

(Problem M to be solved by the invention) In the recording section of non-impact printers, facsimile machines, copiers, etc. that use electrophotography, the positional relationship between the charge wire position of the transfer charger and the photoreceptor is extremely accurate. However, in the conventional configuration, the image forming units such as the photoreceptor unit, developing unit, and cleaning unit are removably attached to a single drawable image forming case, and the transfer charger and registration roller are provided in the main body. It has been difficult to improve the accuracy of the positional relationship between the transfer charger and the charger position, and the positional relationship between the photoreceptor and the registration roller.

Also, when you pull out the image forming case, when you pull out the developing unit and cleaning unit, if toner spills from the opening of the photoreceptor set part of the image forming case, there is no tray to catch the toner, so Spills fall on the floor and make a mess.

In addition, if the arrangement relationships between the upper and lower guide plates before transfer and the photoreceptor drum, and between the upper and lower guide plates before transfer and the registration roller pair are not appropriate, the recording paper may be deflected or the reaction force may be generated due to the miniaturization of the photoreceptor drum, etc. This may cause abnormal images such as misaligned transfer or missing transfer at the rear end.

In addition, as mentioned above, with the structure of the paper feeding system that is assembled into the main body of the device, it takes time to assemble and disassemble each assembly, and it takes a lot of effort to replace parts in the event of a failure, resulting in a decline in service. There has been a demand for a paper feeding system that can easily perform this task.

The present invention eliminates such conventional problems and improves the precision of the positional relationship between the transfer charger, the registration roller, the photosensitive drum, and the paper feeding unit.
It is an object of the present invention to provide an image forming device that is easy to maintain for the user and that causes less toner spillage on the floor.

Further, in claims (2) and (3), the recording paper The purpose of this is to prevent image shift and missing images at the rear end due to deflection and reaction force, and to maintain a normal image.

Another object of the present invention is, in relation to claim (1),
To facilitate assembly and disassembly of one assembly into an apparatus main body by configuring a paper feeding system as a unit, and to maintain positioning accuracy accurately and easily.

(Structure and operation) In order to achieve the above object, in claim (1) of the present invention, the replacement unit is removably housed and pulled out integrally from the machine body, so that it can slide relative to the machine body. a transfer charger unit holding means that is detachably coupled to a lower part of the exchange unit holding means and holds the transfer charger unit so as to be slidable back and forth, and a transfer charger unit holding means adjacent to the transfer charger unit holding means; a registration roller unit holding means that removably accommodates a registration roller, and is configured such that the transfer charger unit and the registration roller unit can be taken in and out integrally with the exchange unit while maintaining a mutual positional relationship with the apparatus main body. This is an image forming device characterized by the following.

According to the present invention, each unit that needs to be replaced and arranged on the replaceable unit holding means with the above-mentioned structure is placed in the exact mutual arrangement, that is, the reference position necessary for operation, when it is in the machine body. When the replacement unit holding means is pulled out of the machine body, the units move relative to each other in a direction away from the reference position. Therefore, since there is sufficient space between the units, it becomes easy to replace the units, and when replacing each unit, the replacement unit can be taken out without damaging adjacent units that are easily damaged.

One aspect of the present invention is that, instead of fixing the transfer charger unit to the machine body side as in the conventional case, the transfer charger unit holding means is attached so as to be rotatable below the replacement unit holding means, and the transfer charger unit is slidable on the transfer charger holding means. to hold the transfer charger unit so that it can be pulled out.

Therefore, when the replacement unit holding means is pulled out from the printer body along with each replacement unit, the transfer charger also moves together, so it functions as a falling toner receiver.
It is possible to prevent stains caused by toner.

In addition, by pulling out the replacement unit holding means from the machine body and then opening the transfer charger unit downward,
Work to deal with paper jams and the like becomes easier6.Furthermore, since the photoreceptor unit and the transfer charger unit are supported by the same replaceable unit holding means, high positional accuracy of both can be maintained.

Further, in the present invention, the registration roller unit is not fixed to the main body of the machine as in the conventional case, but can be fastened and removed by screwing to the image forming case at a position adjacent to the transfer charger unit. Also, when fastening to the imaging case, the positioning holes and bottles provided on the front and rear parts fit into the positioning holes and holes provided on the imaging case, and the alignment of these holes and the bottles is adjusted. With this arrangement, the positional relationship between the photoreceptor and the transfer charger unit can be maintained accurately. By removing the registration roller unit, maintenance, inspection, replacement, etc. of the registration roller can be easily performed.

As described above, the present invention allows the image forming units such as the photoreceptor unit, developing unit, and cleaning unit, the transfer charger unit, and the registration roller unit to be pulled out in the same direction, making maintenance, inspection, replacement, etc. of each part easy. Moreover, the present invention is different from the conventional method in that the positioning between these units can be maintained and set with high precision.

Next, in claim (2) of the present invention, the transfer front is disposed opposite to a tangent line on the photoconductor drum that is made to intersect with a line connecting the center of the photoconductor drum and the transfer charger wire. The tip of the upper guide plate is positioned on the tangent line or slightly above it, and the tip of the other lower pre-transfer guide plate whose plate surfaces are opposite to the upper pre-transfer guide plate is placed on the tangent line or slightly above the tangent line. A pre-transfer guide plate in an image forming apparatus, characterized in that the pre-transfer guide plate is positioned on the tangent line or slightly below the tangent line.

Since the pre-transfer guide plate of the present invention is arranged and configured as described above with respect to the photoreceptor drum and transfer charger, the adhesion between the photoreceptor drum and the recording paper, which causes bending and excessive load on the recording paper, is prevented. Images can be accurately recorded on the entire recording paper.

Further, in claim (3) of the present invention, a pre-transfer upper guide plate disposed on an extension line of a tangent to the pair of registration rollers formed by contacting the pair of registration rollers and the other plate surface are arranged opposite to each other. The lower pre-transfer guide plates are respectively disposed across the tangent line to the registration rollers, and the rear end of the upper pre-transfer guide plate is bent in a direction away from the tangent line on the registration roller side, and is bent in a direction away from the tangent line. A pre-transfer guide plate for an image forming apparatus, characterized in that the pre-transfer guide plate is positioned such that the distance between the image forming apparatus and the image forming apparatus is equal to or less than a predetermined dimension.

According to the present invention, in order to prevent transfer misalignment that occurs immediately after the recording paper passes through the pair of registration rollers, the purpose is achieved by bringing the distance between the tangent line of the pair of registration rollers and the upper guide plate before transfer as close to the pair of registration rollers as possible. be done.

In addition, in the present invention, the paper feeding system is configured as a unit to facilitate assembly and removal of one set to the apparatus main body, and to maintain accurate and simple positioning accuracy, a paper feeding guide plate is provided on the front side of insertion into the apparatus main body. A paper feed unit housing is formed by a pair of paper feed side plates having a cassette guide with a cassette bottom plate rising plate on the rear side of insertion, and a piece with one end bent on the rear side of insertion. There is a pin fitting groove on the bottom plate of the device main body on the insertion front side of the paper feed side plate that fits with a positioning pin whose height is adjustable, and there is also a bent part on the insertion rear side of the paper feed side plate. It has a pin fitting hole that fits with the positioning pin provided on the pillar of the apparatus main body, and has a paper feed drive mechanism that engages with the paper feed drive mechanism of the apparatus main body in the paper feed unit housing, and has a mounting screw. This allows the paper feed unit housing to be attached to and removed from the main body of the apparatus.

With this configuration, the front bin fitting groove and the rear bin fitting hole of the casing can be easily connected to the positioning pins provided at the front and rear positions of the main body of the device such as a printer in the unit-configured casing. By aligning them and attaching them using two mounting screws, the paper feed system drive mechanism of the main body is coupled to the paper feed system drive mechanism in an accurately positioned state. In addition, when replacing obstacles or parts, they can be easily removed from the main body by removing the mounting screws.

In addition, the position of the paper feed unit housing in the height direction is adjusted by using a jig to adjust the positioning pins placed on the bottom plate of the device body using the positioning pins provided on the side plate of the device body as a reference. The positional relationship with the image forming unit can be maintained accurately.

(Embodiment) FIGS. 1 to 11 show an embodiment according to claim (1), and FIG. 1 is a perspective view of a laser printer according to an embodiment of the present invention. , shows a state in which the image forming case (drawer) in which the image forming unit including the transfer charger is set is pulled out. Figure 2 shows
As shown in FIG. 1 and FIG. 2, the laser printer of this embodiment has an image forming case 2 on one side of the printer body 1.
are slidably mounted by support guide rails 3, 3'.

The image forming case 2 includes a photoreceptor unit 4 and a developing unit 5.
, a cleaning unit 6, a toner cartridge 7, and other image forming units are removably housed. Further, a transfer charger unit 8 is detachably attached to the lower part of the image forming case 2. Although not shown in FIG. 1, a registration roller unit 23 shown in FIG. 2 is detachably attached to the image forming case as described later.

When the image forming case 2 is inserted into the printer main body 1, each of these units is installed while maintaining an appropriate positional relationship with respect to each other so that the recording operation by electrophotography can be performed correctly, and the image forming case 2 is inserted into the printer main body 1. The optical writing unit 21, charger 2z, registration roller unit 23, etc. provided on the side are also positioned so as to maintain an appropriate positional relationship.

That is, the positioning pin 2a provided on the printer main body side
, 2b (on the front plate side), 2c, 2d (not shown on the rear plate side), and positioning holes 2a', 2b' (on the front plate side), 20' provided in the imaging case 2.

2d' (rear plate side 2d' is not shown), the image forming case is positioned with the printer body.

By pulling the image forming case 2 out of the printer main body 1, the developing unit 5 and toner cartridge 7 are automatically separated from the photoreceptor unit 4 to the right side in FIG. 2, and the cleaning unit 6 is automatically moved to the left side. be separated from each other. Due to this isolation of units,
When it is time to replace one of the units and it is removed, there is some space between it and the adjacent units, making the work easier and preventing damage to the adjacent units.

A handle 9 for pulling out the image forming case 2 is attached to the front surface of the image forming case 2. Further, the developing unit 5, the cleaning unit 6, and the toner cartridge 7 are each provided with a handle. However, the handle is omitted in FIG. 2 and is not shown; however, the mechanism for attaching and detaching the transfer charger unit and registration roller unit, which is a feature of the present invention, will be described in detail later.

The printer main body 1 includes an image forming case 2 equipped with the above-mentioned image forming unit, an optical writing unit 21 that optically scans the photoreceptor unit, and other components, as well as a first feeder that supplies recording paper. It includes a paper cassette 11, a second paper feed cassette 12, a display section 17, a fixing unit 27 that fixes the toner image on the recording paper developed by one image forming unit by heat and pressure, a transport unit 26, and the like. Further, at the top of the printer main body 1, there is a first paper ejection tray 15 that receives recorded recording paper ejected via the conveyance path 28.
and a second wandering paper tray 16 are provided.

The printer main body 1 also includes a separate mass paper feed unit 14 that is used as an option as needed.
It is placed on an optional unit 18 that includes a reversing unit 13 for reversing the recording paper recorded on one side after exiting the fixing unit 27 and supplying it to the image forming unit again.

By raising the cover plate io and covering the image forming case 2 with the image forming case 2 housed in the main body, it is possible to prevent dust from entering and improve the appearance.

3 and 4 show an example of a mechanism for separating the cleaning unit 6 from the photoreceptor unit 4 by pulling out the image forming case 2. FIG.

Slide hole 31. Cleaning unit holding notch 3
2.32' A pair of sliders 35 and 35' consisting of a spring support protrusion 33 and a cam contact part 34 are arranged at the front and rear of the drawing direction of the image forming case 2, and are slid with respect to the image forming case 2 by a guide pin 36. Fix freely.

A spring 39 is stretched between the spring support protrusion 33 of the slider 35 and a spring support pin 38 fixed to the bottom of the image forming case 2.

In addition, the shaft rod 40 is passed between the front and rear side plates of the imaging case 2,
A cam 41 is fixed at a location corresponding to the position of the cam contact portion 34 of the slider 35, and a spring 37 is attached that biases the shaft rod 40 to rotate in the axial direction.

Although such a cam and spring are not shown in FIG. 3, they are of course provided corresponding to the slider 35'. A pin 42 is provided at the rear end of the shaft 40 so as to engage with a cam 43 provided on the printer main body side.

The cleaning unit 6 has four pins provided at both its front and rear ends, two of which are pins 44° and 44'.
As shown in the figure (only one side is shown), the remaining two pins 45, 45' are fitted into the notches 32, 32' of the slider 35 and held by the slider 35, as shown in FIG.
is the pin support part 46.46' provided on the side wall of the printer body.
is maintained by The pin bearing part 46.46' is the sixth
As shown in the figure, it has a pin slide elongated hole 47 for slidably supporting the pin in the sliding direction, and has a notch 48 above which serves as a pin insertion opening.

In the image forming case 2 holding the image forming unit configured as described above, in the operating position where it is housed in the printer main body 1, the pin 42 at the end of the shaft rod 40 is connected to the printer main body side cam 43. The cam at the back is in contact with the spring 37 and prevents the cam 41 from rotating. Therefore, only the elastic force of the spring 39 effectively acts on the slider 35, 35', and the cleaning unit 6 supported by the slider 35, 35' is positioned close to the photoconductor unit 4, which is the original operating position. . That is, the cleaning unit 6 is pulled to the right in FIG. 3 by the spring 39 (reference position).

On the other hand, when the image forming case 2 is pulled out, the pin 42 at the end of the shaft rod 40 extending from the front and back of the image forming case 2 comes out of the cam 43 on the printer main body side.

The spring force that causes the cam 41 to receive the rotational force of the spring 37 and push the contact portion 34 of the slider 35, 35' is as follows.

Since the spring 37 is stronger than the spring 39, the slider 35 moves to the left in the figure, and as a result, the pins 44, 44' of the cleaning unit 6
By pulling the cleaning unit 6 away from the photoreceptor unit 4.

Although only the cleaning unit 6 has been described above, the developing unit 5 can also be separated from the photoreceptor unit 4 by a similar mechanism when the image forming case 2 is pulled out.

In the above embodiment, in order to automatically separate the units set in the imaging case 2 when the imaging case 2 is pulled out from the printer body, the position of the imaging case 2 is detected and Although the sliding movement of a predetermined unit in response to the detection is performed by a combination of a plurality of cam mechanisms, the present invention is not limited to such a cam mechanism. It can also be realized by a combination of the electromagnetic mechanism and the electromagnetic mechanism driven by it.

FIG. 7 shows a mechanism for attaching the transfer charger unit 8 to the image forming case. The transfer charger unit 8 includes a transposition charger 50 and a transposition charger holder 60. The transposed charger 50 includes a transfer charger section 52
, a separate charger section 53, a rib 54 for smooth paper feeding,
It consists of an electrical connection part 55 with the main body and a handle 56.

This transposed charger 50 includes a transposed charger holder 60
It is held in a detachable manner. The transposed charger holder 60 has rails 61 formed on both sides so that the transposed charger 50 can be slid into or pulled out from the front and held.

The image forming case 2 has an engaging protrusion 64 having a hole 63 for a pin receiver at the back of the lower part where the photoreceptor unit 4 is located.
is provided. A pin 62 is provided at one end of the rear side of the transposed charger holder 60, and when this pin 62 is engaged with the hole 63 of the engagement protrusion 64, the transposed charger holder is rotated about the pin 62 as a rotation axis. 60 is pivoted so that it can be rotated downward.

The front end 66 of the transposed charger holder 60 is bent into an L-shape, and an elastic member 67 such as rubber or soft resin is attached to the end, so that the transposed charger holder 60 can be rotated downward. This prevents the front end from colliding with and damaging the outer wall surface of the printer body. Further, a lock lever 70 having a handle 68 and an engaging portion 69 is rotatably coupled to the front end 66 of the transposed charger holder 60 via a pin 71.

A pin 62 is provided on the front side of the imaging case 2 to engage with the engaging portion 69 of the lock lever 70 and support the transposed charger holder 60.

In the above configuration, when replacing the unit or clearing paper jams, the image forming case 2 is pulled out from the printer main body 1 by pulling the handle 9 toward you as shown in FIG. Since predetermined units such as the cleaning unit 6 and the developing unit 5 are automatically moved away from the photoconductor unit 4 according to the situation, there is more space between the units, making it easier to replace the units. In addition, when replacing each unit, adjacent units that are easily damaged, such as the blades of the photoconductor unit 4 and cleaning unit 6, will not be damaged.
Furthermore, there is less toner spilling from the cleaning unit 6 and the developing unit 5, and replacement units can be removed.

Furthermore, even if toner spills from the lower opening at the set position of the photoreceptor unit 4 when the imaging case 2 is pulled out, the transfer charger 50 is pulled out together with the imaging case 2 to receive the spilled toner. Since the opening serves to prevent toner from spilling onto the floor from the opening when the image forming case 2 is pulled out.

In addition, when the image forming case 2 is housed in the printer main body 1, even if toner is spilled from the cleaning unit or developing unit, the transfer charger 5
When set to 0, the receiver is stopped and the inside of the printer body can be prevented from being contaminated.

When handling paper jams, etc., pull out the image forming case 2 from the printer main body 1 and then pull the first handle 68 toward you to disengage the lock lever 70. transposed charger 50
together rotate downwards about the pin 62,
Since it is separated from the photoreceptor unit 4, paper jams can be easily cleared.

Further, when replacing the transposing charger 50 or collecting and discarding toner that has fallen and accumulated in the transposing charger, the transposing charger 50 can be taken out by pulling the first handle 56.

FIG. 8 is a perspective view showing a mechanism for attaching the registration roller unit 23 to the image forming case, and FIG. 9 is a side view seen from the direction of the arrow. The registration roller unit 23 is
A conveying metal roller 72, a conveying rubber roller 73, and a conveying roller unit frame 74 supporting shafts at both ends of these rollers.
．． Roller bearing 75. It consists of a pressure spring 76 for the metal transport roller, a pressure arm 77, a pre-transfer guide plate 78, and a pre-transfer roller guide plate 79.

This registration roller unit 23 has a hole 74a for positioning the conveyance roller unit in a frame 74 on the front plate side, and a pin 74b for positioning the conveyance roller unit on the frame 74 on the rear plate side. As shown in the mechanism, the image forming case 2 has ribs 2' for positioning the image forming case and the conveyance roller on the front and rear plates of the image forming case 2, respectively. The rib 2' of the front plate has a positioning pin 74b' that fits into the hole 74a, and the rib 2' of the rear plate has a positioning pin 74b' that fits into the hole 74a.
has a positioning hole 74a' into which the pin 74b is inserted.
has.

That is, in the registration roller unit 23, the positioning pin 74b' on the front plate side is fitted into the positioning hole 74a, and the registration roller unit 23 is fastened to the rib 2' of the front plate with the set screw 80. Further, the positioning pin 74b on the rear plate side is fitted into the positioning hole 74a', and is positioned on the front and rear surfaces. Pin 7 mentioned above
4b, 74b' and hole 74a.

74a' is disposed on a rib or frame so as to be positioned in a shaft-sealing manner with the transfer charger unit 8 and photoreceptor unit 4.

FIG. 11 shows a perspective view of the drive mechanism of the registration roller unit 23, and the conveyance rubber roller 73 shown in FIGS. 8 and 9
The conveyor roller drive gear 8 is connected to the shaft of the conveyor roller via a spring 81.
2 is pressed against the shaft end by an E-ring 83 and fixed to the shaft. Note that 84 is a drive gear on the printer main body side, 85 is a timing belt, and 86 is an electromagnetic clutch.

As shown in FIG. 10, the registration roller unit 23 is removably attached under the image forming case 2 with a set screw 80, so when the image forming case 2 is pushed into the printer body 1, the registration roller unit 23 is removed. As shown in FIG. 11, the transport roller drive gear 8 moves in the direction of arrow (2).
2 hits the drive gear 84 on the printer main body side, the conveyance roller drive gear 82 moves in the direction of arrow (1), and when both gears 84 and 82 mesh, the spring 81 causes the conveyance roller drive gear 82 to move in the direction of arrow (3). ) direction, and meshes with a drive gear 84 on the printer main body side, so that the drive from the printer main body side is transmitted to the conveying rubber roller 73 and rotates.

In the registration roller unit 23, the paper ejected from the paper feed cassette 11.12 shown in FIG. 2 is guided to the nip of the transport roller by the transport roller front guide plate 79 shown in FIG. The transferred paper is guided by the pre-transfer guide plate 78 and guided to the transfer charger unit 8 and photoreceptor unit 4, which are arranged in a predetermined positional relationship.

Furthermore, the conveying metal roller 72 is relative to the conveying rubber roller 73.
As shown in FIG. 9, the pressure is applied to the side surface of the roller 72 via a pressure arm 77 which is rotatably supported by a frame 74 by a pressure spring 76.

FIG. 12 shows an embodiment according to claim (2) of the present invention,
The same numbers and symbols as in FIGS. 14 and 15 are the same.

Until now, as shown in Figs. 14 and 15, abnormal images such as transfer misalignment and transfer missing on the recording paper have occurred due to poor adhesion between the photosensitive drum 4A and the recording paper, especially at the trailing edge of the recording paper. Attributable to doing.

Therefore, as a means to improve the adhesion between the photoreceptor drum and the recording paper, for example, increasing the transfer current and strengthening the transfer electric field can be considered, but this is less effective when the movement of the trailing edge of the recording paper is unstable. Therefore, in order to improve the transferability of the trailing edge of the recording paper, it is necessary to make the paper feeding itself smooth to make the movement of the recording paper uniform.

In this embodiment, the pre-transfer lower guide plate 78B is mounted on the photoreceptor drum 4 so as not to cause unnecessary bending or load on the recording paper.
Based on the experimental results, the line connecting the center 4a of A and the transfer charger wire 8a of the transfer charger unit 8 forms a tangent 90 on the photoreceptor drum 4A, and the distance from this tangent is slightly on or from the tangent. The tip end 78b of the lower pre-transfer guide plate 78B was positioned so that it was approximately 0.5- or less.

Table (1) below shows that the distance of the lower pre-transfer guide plate 78B is 0.
．． It shows the state of transfer misalignment and missing parts (X marks) when displaced by 5I, and + in the distance indicates a downward direction with respect to the tangent line 90. As is clear from this experimental result, on the tangent line 90 (On
It was confirmed that there were no transfer deviations or omissions (marked 0) within the range below (+0.5aa) from 0.m) or below (+0.5aa).

On the other hand, when looking at the pre-transfer upper guide plate 78A,
If it is above the tangent line 90 or slightly above the tangent line (distance - mark), there will be no transfer misalignment or missing parts (0 mark) as shown in table (2) below.
.

In addition, the Δ marks in the tables (1) and (2) below are between those with no transfer deviation or missing parts (0 mark) and those with transfer deviations or missing parts (X mark).
From a normal image recording perspective, this distance can be said to be a problem.

Table (1) Table (2) FIG. 13 shows an embodiment according to claim (3) of the present invention,
The same numbers and symbols as in FIG. 16 are the same.

Conventionally, it has been mentioned that as the photoreceptor drum 4A becomes smaller, the adhesion between the photoreceptor drum and the recording paper deteriorates because the angle at which the recording paper enters the photoreceptor drum becomes steeper.

Furthermore, the recording paper that has passed through the pair of registration rollers 23A and 23B is bent and the force of returning toward the pre-transfer upper guide plate 78A is large, and the trailing edge of the recording paper also moves significantly toward the guide plate 7111A, causing fluctuations in the recording paper in the transfer area. Transmission, transcription deviation,
Abnormal images with missing transfers occur.

In this embodiment, in order to prevent this, the force that causes the bent recording paper to return to its original position, that is, the reaction force, is reduced, and after the trailing edge of the recording paper passes through the pair of registration rollers, the pre-transfer upper guide plate 78A Try to reduce the distance that it hits.

As shown in FIG. 13, the rear end portion 78a2 of the pre-transfer upper guide plate 78A on the registration roller side is bent in the direction away from the pair of registration rollers and lX92, and the rear end portion 78a2 of the pre-transfer upper guide plate 78A on the registration roller side The end 78a2 is.

For example, the distance between the registration roller pair and the tangent line 92 is set to 2.
I made it less than m.

According to the experimental results, the relationship between the above-mentioned distance and transfer deviation was examined at four points as shown in Table (3) below.

There is no transfer deviation when the distance is 1 to 2I or less (O mark).

It was confirmed that when the distance was 3 m or more, there was a possibility that transfer deviation would occur (Δ mark) and that it would occur (X mark).

Table (3) Next, an embodiment of the unit configuration of the sheet feeding system will be described.

The shaded area in FIG. 2 is the applicable area, and since it can be implemented in the same way for a copying machine with almost the same mechanism, the case of a printer will be described here.

In Fig. 2, 1a is a pillar of the printer body, 1b is the bottom of the printer body, 100 is a paper feed unit, which will be described later, and 10
1 and 102 are upper and lower paper feed rollers, respectively, which are built into the paper feed unit housing.

Next, the structure of the paper feeding unit 100 is shown in FIG.
The figure is a perspective external view of the same, and 103 is a paper feed guide plate;
04 is a cassette guide of the paper feed cassette, 105 is a cassette bottom plate rising plate installed in the center of the cassette guide,
The paper feed side plates 106 and 107 have pieces 106' and 107' whose ends are bent. LO6a (107
(a not shown in the drawing) is a positioning pin fitting groove 106b provided at the front protruding end.

107b is the rear bent portion 106', 107
Pin fitting hole for positioning provided in ', 106c, 1
Reference numeral 07c indicates an insertion hole for a mounting screw 108 (FIG. 18) provided in the bent pieces 106' and 107', and this portion is the bent piece 106''.

107' is subjected to drawing processing. As can be seen, the folded pieces 106' of the paper feed side plates 106, 107,
The bent surface of 107" is shaped to connect with the - side of the pillar 1a (Fig. 18) of the printer main body, and both paper feed side plates 106.10
7, the paper feed guide plate 103, and the cassette guide 104 form a housing.

Also, paper feed cassette 11.12 and paper feed roller lot, 1
02 is the paper feed side plate 1 that holds the paper feed roller.
A cassette guide 104 is installed on the same side plate surface as 06 and 107 to hold the paper feed cassettes 11 and 12, so that the accuracy of the positional relationship can be easily achieved using only the accuracy of the parts. Therefore, there is no need to adjust this part.

FIG. 18 shows a perspective external view when the paper feed unit 100 (casing) of FIG. 17 is attached to the printer main body, and
FIG. 19 is a plan view showing the positioning relationship when the paper feed unit 100 is attached to the printer body, and FIG. 20 is a perspective external view showing the structure of the positioning pin 1d attached to the bottom plate 1b of the printer body.

In the above figures 18 to 20, 1c and 1d
is a positioning pin, lc is attached to the column 1a, and 1d is attached to the bottom plate 1b.
This position is located above the paper feed unit 100 (
When the photoreceptor unit 4 (FIG. 17) is attached to the main body, the positional relationship between the photoreceptor unit 4 and the photoreceptor unit 4 can be accurately seen.

That is, each of the left and right positioning pins 1c is connected to the paper feed unit 1.
00 pin fitting holes 106b and 107b, and the grooves 1d'' of the left and right positioning pins 1d correspond to the pin fitting grooves 10.
6a and 107a.

Here, the first positioning pin 1d is a screw hole 109a of the bracket support plate 109 having a cross-sectional shape as shown in FIG.
It is fixed to a bracket 111 which is fixed with a mounting screw 110 to a bracket 111 by caulking, welding, or the like.

The bracket 111 has a long hole 111a, and the bracket 1
11 is adjustable in the height direction (arrow C).Furthermore, the bottom plate portion of the bracket support plate 109 is fixed to the bottom plate 1b of the printer main body.

The paper feeding unit 100 is set in the printer body from the direction of arrow A as shown in FIG. 18, while the image forming case 2 is set from the right angle direction as shown by arrow B, so the positioning between both units is easy. In this embodiment, the hole 200 for positioning the image forming case 2 shown in FIG.
Positioning pins 201a (front) and 201b (rear) for inserting the imaging case to fit into a (front) and 2oob (rear), respectively.
The side plates 112A (front) and 112B of the printer main body
(rear), and is positioned with respect to the paper feed unit 100. Also, the main body side plate 112^.

112B is fixed to the pillar 1a while maintaining positional accuracy.

Next, the positioning pin 1d of the paper feeding unit 100 will be described. As already mentioned, the positioning pin 1d of the paper feed unit 100 is fixed by adjusting the height position from the bottom plate 1b of the printer body using the elongated screw hole 111a of the bracket 111 shown in FIG. It has become.

Other units shown in FIG. 2 that require this adjustment (optical writing unit 21, transport unit 26, fixing unit 27, etc.)
Since positioning is performed on the same side plates 112A (front) and 112B (rear) of the printer main body, it is easy to achieve positional accuracy between each unit.

In addition, the paper feed unit 100 also has a first mounting screw 108 side.
As shown in Fig. 8, the side plate 1 of the printer main body is
12j (front) and 112B (rear) for accuracy, but the pin fitting groove 106a on the front side of the paper feed unit.

107a is positioned using the positioning pin 1d on the bottom plate 1b, so it is difficult to achieve positional accuracy (this is the column 1a).

(Because tolerances of parts such as the position of the bottom plate 1b and the positioning pin 1d of the bracket 111 accumulate), so in this embodiment,
Image forming case 2 positioning pin 201 a (front) on printer main body side plate 112A (front L Li2O (rear))
.

201b (rear) is used to position the positioning pin 1d of the paper feed unit l-100.

The positioning method is to use the T-shaped jig 113 shown in FIG. 18, fit the upper jig hole 113A into the positioning pin 201a for the imaging case, and fit the lower jig hole 113B into the positioning pin 1d. , after that, driver D took the 20th
The mounting screw 110 shown in the figure is inserted into the elongated hole 111a of the bracket 111.
By fixing it in the screw hole 109a using the screw holes 109a, the positional relationship with the printer main body side plates 112A (front) and 112B (rear) can be precisely obtained.

Here, since the positioning pin 1d is for achieving accuracy in the height direction, the height of the height X and width Y of the upper and lower jig holes 113A and LL3B of the T-shaped jig 113 is The dimension X requires high precision.

To set the paper feed unit 100 configured as above in the printer body, push it in the direction of arrow A. The pin fitting grooves 106a and 107a are now aligned with the positioning pin 1.
d into the groove 1d', and the pin fitting hole 106b,
107b fits into the positioning pin IC.

Then, attach the pillar 1a to the bent piece 106' using the mounting screw +08.
.

If the screws are removed during step 107' and then screwed in using the locking washers 114, the positional relationship between the photoreceptor unit and the paper feeding unit is set correctly.

To remove the printer from the main body, loosen the mounting screws 108 and pull out the housing in the direction opposite to the direction of arrow A.

FIG. 21 shows the coupling relationship between the printer main body and the paper feed unit (FIG. 17), in which (1) is a side view and (2) is a front view, 115 is a drive gear of the printer main body; 1
16 is a pulley and gear, 117 is a drive motor, and 118 is a drive belt. Further, the paper feed pulleys 119 and 120 of the paper feed unit 100 are connected to the drive belt 1.
21, the pulley 12 is integrated with the paper feed unit gear 122.
2'. The paper feed unit gear 122 described above meshes with the drive gear 115 of the printer main body (see FIG. 21 (2)).
)). The positioning pin 1d and pin fitting groove LO6a shown in FIG.
(107a) are fitted together. Therefore, drive is transmitted from the drive gear 115 of the main body to the paper feed unit, the pulley 122' of the paper feed unit integrated with the paper feed unit gear 115 rotates, and the paper feed drive belt 121 moves the paper feed rollers 101 and 102. Driving boo January 19.1
20 feeds paper in conjunction with each other.

Note that although the registration roller unit 23 is not included in the paper feeding unit in this embodiment, it may be integrated.
The driving source may also be provided independently without being supplied from the main body.

(Effect of the invention) As explained above, according to the invention described in claim (1),
The photoconductor unit, transfer charger unit, and registration roller unit are attached to the same image forming case, and they move together when one image forming case is taken in and out, and their mutual positional relationship remains constant. This has the advantage of making it easier to achieve positional accuracy between the roller and the registration roller.

Further, since the image forming case and the printer main body are fitted through positioning holes and pins, the positional relationship with other units can be maintained with high precision. Furthermore, since the registration rollers are made into a unit, it is easier to assemble the transport roller system into the printer main body because restrictions on the order etc. are relaxed.

Furthermore, since the registration roller parts can be replaced outside the printer body, maintenance and inspection are easy. Further, since toner falling from the cleaning unit and developing unit is received by the case of the transfer charger, it is possible to prevent toner from staining inside the printer body and from spilling toner on the floor when the image forming case is pulled out.

According to the invention described in claim (2), the tips of the pre-transfer upper and lower guides are connected to the tangent line on the photoreceptor drum that intersects the line connecting the center of the photoreceptor drum and the transfer charger wire. tangent to the reference, or slightly above and below, respectively.
By positioning the recording paper, unnecessary bending or load is not created on the recording paper, the recording paper is brought into close contact with the photoreceptor drum smoothly, and a normal image can be recorded without transfer missing or misalignment, especially at the trailing edge of the recording paper.

Further, according to the invention described in claim (3), the pre-transfer upper and lower guide plates are arranged to sandwich the tangent to the registration rollers, and the rear end of the pre-transfer upper guide plate is bent in a direction away from the tangent. By reducing the distance between the two registration rollers, the reaction force of the recording paper passing through the pair of registration rollers is reduced, thereby preventing transfer misalignment and allowing normal image recording.

In addition, one aspect of the present invention relates to the invention described in claim (1), and provides a pin fitting groove and a pin fitting hole that fit into a positioning bin provided in a predetermined position of a main body of an apparatus such as a printer in a paper feeding unit. The system ensures accurate positioning of the image forming unit 8 such as the photoreceptor unit 6 and the paper feed unit 2, and its installation,
It can be easily removed using two mounting screws. Also.

The paper feed system drive mechanism is precisely and easily engaged with the drive mechanism of the printer main body by the above positioning.

[Brief explanation of the drawing]

1 to 11 show each embodiment according to claim (1) of the present invention, FIG. 1 is a perspective view of a laser printer according to an embodiment of the present invention, and FIG. 2 is a perspective view of a laser printer according to an embodiment of the present invention. 3 and 4 are views of an example of a mechanism for separating the cleaning unit 6 from the photoreceptor unit 4 by pulling out the image forming case 2, and FIG. 5 shows the cleaning unit. FIG. 6 is a diagram showing a pin support portion, and FIG. 7 is a perspective view showing a mechanism for attaching the transfer charger unit to the imaging case 2. Fig. 8 is a perspective view showing the mechanism for attaching the registration roller to the image forming case, Fig. 9 is a side view of Fig. 8, and Fig. 1O is a perspective view showing the attaching mechanism for the image forming case, the registration roller unit, and the main body. , FIG. 11 is a perspective view showing a drive mechanism for the registration roller unit and the main body. FIG. 12 is a diagram showing an embodiment according to claim (2) of the present invention. FIG. 13 is a diagram of an embodiment according to claim (3) of the present invention, and FIGS. 14 and 15 are explanatory diagrams of the arrangement of a conventional pre-transfer guide plate related to claim (2) of the present invention. FIG. 16 is an explanatory diagram of the arrangement of the conventional pre-transfer guide plate related to claim (3) of the present invention, and FIGS. 17 to 21 are related to claim (3) of the present invention.
1) Examples of paper feeding units related to the description are shown; FIG. 17 is a perspective external view of a paper feeding unit according to one embodiment, and FIG. 18 is a perspective external appearance when the paper feeding unit shown in FIG. 17 is attached to the printer main body. 19 is a plan view of the paper feed unit attached to the printer body, and FIG. 20 is a diagram showing the structure of the positioning pin 1d attached to the bottom plate 1b of the printer body. FIG. 21 is a diagram showing the connection between the printer main body and the paper feeding unit. ■...Printer body, 2...Image forming case, 2'
... Rib, 2a to 2d... Positioning pin,
2a'~2d'...Positioning hole, 3°3'
...Support guide rail, 4...Photoconductor unit,
4A...Photosensitive drum, 4a...Center, 5
...Developing unit, 6...Cleaning unit, 7...Toner cartridge, 8...
- Transfer charger unit, 8a... Transfer charger wire, 9... Handle, 10... Cover plate, 11, 1
2... First and second paper feed cassettes, 13... Reversing unit, 14... Mass paper feeding unit, 15.16...
1st. Second paper output tray, 17...Display section, 18...
Optional unit, 21... Optical writing unit, 2
2... Charger, 23... Registration roller unit, 23A. 23B... Registration roller, 26... Conveyance unit, 27... Fixing unit, 28... Conveyance path,
31...Slide hole, 32.32'...Cleaning unit holding notch, 33...Protrusion, 35.
35'...Slider, 36...Guide pin, 37
, 39... Spring, 40... Shaft rod, 42...
Pin, 41.43...Cam, 44°44', 45
．． 45'... Pin, 46.46'... Pin support portion, 47... Long hole, 50... Transposed charger, 5
2... Transfer charger part, 53... Separated charger part, 54... Rib, 55... Electrical connection part with main body, 56... Handle, 60... Transposed charger holder, 61 ... Rail, 62... Pin, 63...
Hole, 64... Engaging protrusion, 66... Front end, 67...
- Elastic member, 68... Handle, 69... Engaging portion, 70
...Lock lever 71...pin, 72...conveyance metal opening -ra, 73...conveyance rubber roller. 74... Conveyance roller unit frame, 74a,
74a--locating hole, 74b. 74b'... Positioning bin, 75... Roller bearing, 7G... Pressure spring, 77... Pressure arm, 78... Pre-transfer guide plate, 78A... Pre-transfer guide plate, 78B... Lower guide plate before transfer, 78 a □,
78b, -tip, 78a,. 78b2...Rear end portion, 79...Pre-conveyance guide plate, 8
0... Set screw, 81... Spring, 82°84
...Drive gear, 88...E ring, 85...Timing belt, 86...Electromagnetic clutch, 90...Tangential line, 91...Recording paper, 92...Tangential line to registration roller, la ...Pillar of the printer body, 1b...
・Bottom plate of the printer body, lc, ld...positioning pin, ld'...positioning groove, 100...paper feed unit, 101...upper paper feed roller, 102...lower paper feed roller , 103... paper feed guide removed, 104...
Cassette guide, 105...Cassette bottom plate rising plate, 1
06.107--Paper feed side plate, 106a. 107a - pin fitting groove, 106b, 107b
---Pin fitting hole, 106c, 107c
...Mounting screw insertion hole, 108...Mounting screw, 114
...Washer, 112A...Main body side plate (front),
112B... Body side plate (rear), 201a... Positioning pin for image forming case (front), 201b... Positioning pin for image forming case (rear). Patent applicant Ricoh Co., Ltd. - Figure 31゛°Also 4th hole 32.32'...Uni, To stock invitation'@0+63 drunk, 4
4.44', 45...Jin 35.35'...Sliter 1 Figure Figure Figure 78 Roll! Leopard power sheet plate 79...塘(4'Roak front roller (8o-h, -1) 83...E ring 84...Main salary, moving ear 85...Timing beret 86...Electricity is the cause of clatte Figure 103 = Muzuaku mokaidoya l, +05...force t Udokaiki & toke board 1060... Bin offering groove 106c, 107c... Installation winter samurai〉\)shi 1
04... Cassette card 0id 106, +07... Paper feed stripping plate +06b, +07t),,, Hi0in section 6, 106',
+07'-...Hoko 17' part stomach diagram 110 installation diagram Figure 21 NeG paper, unit east bed winter U゛B (,chi. Yasaya drive t-ri 106a, 107a ・Bin' assembly hsk 119
．． 120,122' 柘゛盵Unit Boots 22
Order structure d unit excellent 4 k'V6 kid table)
``-tsu γ) Toju'ya 8 Sabeki Island Village Ika) Ret procedure Neill, tE 1q; (Method)] % formula % 2, Title of invention Imaging device 3, Amendment person case Related Applicant Address 1-3-6 Nakamagome, Ota-ku, Tokyo Name
Name (1374) Rico Co., Ltd. Representative
Hama 1) Hiro 4, Agent 5゜6゜ Procedural amendment order attached 11, 1986 + 2JJ 121T! Target of amendment Drawing (Shipping date December 20, 1986) Figure 21 115 ・' Honsho toy rule) M-Misanriki\Paki? +2
2 ゛-°Feed low paper feed 122'...Paper feed unit boot b

Claims (3)

[Claims] (1) A replacement unit holding means that is slidable relative to the machine body in order to removably accommodate the replacement unit and integrally pull it out from the machine body, and a lower part of the replacement unit holding means that can be opened downward. A transfer charger unit holding means that is coupled to the transfer charger unit and slidably holds the transfer charger unit back and forth, and a registration roller unit holding means that removably accommodates a registration roller adjacent to the transfer charger unit holding means, An image forming apparatus characterized in that the unit and the registration roller unit are configured so that they can be taken in and out integrally with the replaceable unit while maintaining a mutual positional relationship with the main body of the apparatus. (2) The tip of the pre-transfer upper guide plate, which is disposed opposite to a tangent on the photoreceptor drum that intersects with a line connecting the center of the photoreceptor drum and the transfer charger wire,
The tip of the other pre-transfer lower guide plate, which is located on or slightly above the tangent line and whose plate surfaces are opposite to the pre-transfer upper guide plate, is positioned on or slightly above the tangent line. A pre-transfer guide plate in an image forming device, characterized in that the guide plate is positioned below. (3) The upper pre-transfer guide plate, which is arranged on an extension line of the tangent to the registration rollers formed by a pair of registration rollers in contact with each other, and the lower pre-transfer guide plate, whose plate surfaces are arranged to face each other, are as follows:
The rear end portions of the upper pre-transfer guide plates are arranged to sandwich a tangent line to the registration rollers, and the rear end portion of the upper pre-transfer guide plate is bent in a direction away from the tangent line, and the distance from the tangent line is less than a predetermined dimension. A pre-transfer guide plate in an image forming device, characterized in that the pre-transfer guide plate is positioned as shown in FIG.