JP2906072B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which rotation of an image carrier is detected by an encoder to form operation timing.

[Conventional technology]

Generally, in an electrophotographic or electrostatic recording type image forming apparatus, a drum-shaped image carrier is generally used. The electrostatic latent image on the image carrier is formed by synchronizing the moving speed of the image carrier with the writing means. As a method of synchronizing, there are a method in which the rotation accuracy of the image carrier is increased and printing is performed at a fixed timing, and a method in which rotation of the image carrier is detected by an encoder and printing is performed based on an output signal.

The present invention relates to an image forming apparatus that performs printing based on a detection signal of the latter encoder, and a conventional configuration example of an image forming apparatus of such a method is shown in FIGS.
This will be described with reference to the drawings. In the configuration example shown in FIG. 8, an image carrier and an encoder are integrally attached, and a flange 2 is press-fitted or screwed to an end surface of the image carrier 1. 2 is positioned and fixed to the apparatus body frame (side plate) 6 via the bearing 4 and the housing 20. Further, a gear A21 that is engaged with a gear of a drive system (not shown) of the apparatus main body is attached to the flange 2. An encoder 19 for detecting the rotation speed (or rotation fluctuation) of the image carrier 1 is mounted on the end of the flange 2 of the image carrier 1 coaxially with the image carrier 1, and the encoder body is attached by a bracket 18 to the apparatus body. It is configured to be fixed to the frame 6.

The configuration example shown in FIG. 9 is configured so that the process unit can be attached to and detached from the apparatus main body. The process unit 5 includes a cleaning unit for removing residual toner on the image carrier 1 after transfer, and a cleaning unit for the image carrier 1. It is composed of a plurality of process elements such as a static eliminator for eliminating charges. The flange 2 press-fitted or screwed to the end face of the image carrier 1 is attached to a process unit 5 via a bearing 4.
A gear A21 that meshes with the drive system on the apparatus main body side, and an encoder 19 is mounted coaxially on the flange 2. The main body of the encoder 19 is mounted on the process unit 5 by a bracket 18, and the process unit 5 is mounted on the apparatus main body frame. 6 is configured to be removably attached.

The configuration example shown in FIG. 10 is similar to the configuration example shown in FIG. 9, in which the process unit 5 is detachably attached to the apparatus main body, and the encoder 19 is attached to a shaft 25 which is a driving unit on the apparatus main body side. It is configured to be attached. The tenth
In the drawing, reference numeral 22 denotes a sleeve attached to the device main body frame 6 supporting the shaft 25, 23 denotes a bearing of the shaft 25 fixed to a gear bracket 26 fixed to the device main body frame 6,
Reference numeral 24 denotes a gear B fixed to a shaft 25 engaged with the gear A21.

[Problems to be solved by the invention]

By the way, in the conventional configuration example shown in FIG. 8, since the image carrier 1 and the encoder 19 are integrally mounted, high rotation detection accuracy can be obtained. However, since the encoder 19 is attached to the apparatus main body frame 6, there are many places where the apparatus is disassembled during maintenance work such as replacement of the image carrier 1, and the configuration does not have high maintenance. Is impossible.

Further, in the configuration example shown in FIG. 9, since the process unit 5 can be attached to and detached from the apparatus main body, the attachment and detachment of the process unit 5 for exchanging consumable parts can be performed by a general user. The detection accuracy of the encoder 19 is also high as in the conventional example shown in FIG. However, according to this configuration, every time the process unit 5 that is periodically replaced is replaced, the expensive encoder 19 is replaced at the same time, and there is a disadvantage that the cost of the process unit 5 increases. If the encoder 19 is replaced when the process unit 5 is replaced, the cost can be reduced. However, replacement by a general user cannot be expected, the work is performed by a service person, and the integrity of the general user is not secured.

Further, in the configuration example shown in FIG. 10, since the encoder 19 is attached to the drive system on the apparatus main body side, even if the process unit 5 is replaced, it is necessary to replace the encoder 19 at the same time and to perform a replacement operation. do not do. However, as a drawback of this conventional example, the encoder 19 detects not the rotation of the image carrier 1 but the rotation of a drive system arranged near the image carrier 1, and the rotation including the influence of backlash and the like. Is detected. As a result, the synchronization between the image carrier 1 and the means for writing the latent image is not completely achieved, and the quality of the image to be printed is adversely affected.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problem in the conventional image forming apparatus, and has made it possible to detect the rotation of the image carrier with high accuracy without impairing the integrity of the user. It is an object to provide an image forming apparatus.

[Means and Actions for Solving the Problems]

In order to solve the above problem, an image forming apparatus according to the present invention is provided in an image forming apparatus that detects rotation of an image carrier and forms an operation timing based on a detection signal, the image forming apparatus being detachably provided in the apparatus main body. An image carrier having a rotation axis, and an encoder having an encoder axis for rotation detection,
A support frame rotatably supporting the encoder shaft and movably provided in the apparatus main body; a joining portion formed on a rotation shaft of the image carrier; and a rotation frame formed at an end of the encoder shaft. And a joint for positioning the encoder shaft coaxially with the rotation axis by joining the joint to the joint of the rotation shaft and the encoder shaft when the image carrier is mounted on the apparatus main body. The encoder shaft is positioned coaxially with respect to the rotating shaft by joining the parts.

With this configuration, the image carrier is detachably provided on the apparatus main body, and the encoder is supported by the support frame movably provided on the apparatus main body, so that there is no need to replace the encoder. The image carrier can be easily replaced. Also, when the image carrier is mounted on the apparatus main body, the joint of the rotating shaft of the image carrier and the joint of the encoder shaft of the encoder are coaxially positioned and joined, so that the rotation of the image carrier by the encoder is high. It is possible to detect with high accuracy.

〔Example〕

Hereinafter, embodiments will be described. FIG. 1 is a schematic sectional view showing a first embodiment of the image forming apparatus according to the present invention,
The same or equivalent members as those in the conventional example shown in FIGS. 8 to 10 are denoted by the same reference numerals. A flange 2 is attached to the image carrier 1 by fastening means such as press fitting or screwing. A drum shaft 3 having a tapered portion 3a at the tip is press-fitted into the flange 2. The image carrier 1 to which the flange 2 and the drum shaft 3 are attached is attached to a process unit 5 via a bearing 4 fixed to the drum shaft 3. The process unit 5 includes a plurality of process elements such as a cleaning member and a charge removing member.

Next, the configuration of the apparatus body will be described. A two-stage cylindrical housing 12a is formed in the encoder support frame 12, and a bearing 17 is press-fitted into the inner part of the cylindrical housing 1a. The bearing 17 supports a tapered shaft 15 having a tapered shape in which a tip fitting portion 15a is fitted to the tapered portion 3a of the drum shaft 3 so as to be slidable in the axial direction. Reference numeral 15b is disposed so as to protrude from the opening of the cylindrical housing 12a of the encoder support frame 12. The above taper shaft 15
Is biased in the direction of the drum shaft 3 by a spring 14 disposed between a nylon sheet 16 serving as a spring receiver abutting against the end face of the bearing 17 and a step portion 15c of the tapered shaft 15. .

The other end 15b of the tapered shaft 15 has a shaft 1
9a is mounted coaxially, and the main body of the encoder 19 has
As shown in FIG. 2, the bracket 18 is fixed,
A cut-out recess 18a is formed at the other bent end of the bracket 18, and the cut-out recess 18a fits into a protruding slide portion 12b formed on the outer surface of the cylindrical housing 12a of the encoder support frame 12. , Whereby the encoder 19
The bracket 18 is restricted so that its movement in the rotational direction with respect to the axis is free from the movement in the axial direction indicated by the arrow.
Supported by That is, when the taper shaft 15 slides in the axial direction, the encoder 19 also slides.

A roller one-way clutch 8 through which the drum shaft 3 passes is press-fitted into the center of the pulley on which the belt 13 is hung. A boss 9a is formed on the pulley 9, and a bearing 11 is press-fitted into the boss 9a.
The outer ring of the bearing 11 is attached to the peripheral wall of the inner step portion of the housing 12a of the encoder support frame 12 with play. Further, the pulley 9 is configured so as not to come off from the encoder support frame 12 via the bearing 11 by a stopper 10 protruding from an opening of the housing 12a of the encoder support frame 12.

The encoder support frame 12 and the apparatus main body frame 6 are attached as shown in FIG. 4 (A) or (B). That is, first, as shown in FIG. 3 (A), a shaft 27 having a step surface 27a having a diameter d smaller than the diameter D of the hole 12c formed in the encoder support frame 12 is fixed to the apparatus main body frame 6, and Insert the hole 12c of the encoder support frame 12 into the shaft 27, and
Is screwed onto the shaft 27 to hold the encoder support frame 12 on the apparatus main body frame 6. Alternatively, as shown in FIG. 3 (B), a seat 30 having a threaded portion is attached to the apparatus main body frame 6, the hole 12c of the encoder support frame 12 is brought into contact with the seat 30, and the holding spring 28 is A step screw 31 having a diameter d smaller than the diameter D of the hole 12c is screwed to the seat body 30 so that the encoder support frame 12 is supported by the apparatus main body frame 6. As shown in FIG. 4, the encoder support frame 12 has three holes 12c. The holes 12c are supported by the cup screws 29 or the step screws 31 via the holding springs 28 as described above. Part 12
The looseness between c and the shaft 27 or the step screw 31 is freely supported by the apparatus body frame 6.

Next, the mounting operation and the driving operation of the process unit 5 to the apparatus main body in the image forming apparatus configured as described above will be described. Process unit 5 including image carrier 1
Is inserted into the apparatus body by being guided by a guide member (not shown) on the apparatus body side. At this time, as the process unit 5 is inserted, the drum shaft 3 passes through the hole 6a provided in the apparatus main body frame 6, penetrates the roller one-way clutch 8 provided in the pulley 9, and the taper shaft 15 Is pressed against the encoder 19 side. At this time, the boss 5a of the process unit 5 is inserted into the positioning hole 6b of the apparatus body frame 6, and the tapered portion 3a of the drum shaft 3 is inserted.
And the tip fitting portion 15a of the tapered shaft 15 is fitted.
As a result, the process unit 5 is
, And the position of the image carrier 1 with respect to the apparatus main body is determined.

At this time, the drive pulley 9 and the encoder 19 on the apparatus main body side for driving the image carrier 1 are attached to the apparatus main body frame 6 with play and are configured to be slightly movable, so that the image carrier 1 With the insertion of the drum shaft 3 which is coaxial with the image carrier 1, the drum shaft 3 is positioned coaxially with the image carrier 1. Further, the drum shaft 3 and the taper shaft 15 are pressed against each other by the pressing force given by the spring 14, and a frictional force sufficient to rotate the encoder 19 is generated, and the rotation of the image carrier 1 is reliably transmitted to the encoder 19. Will be.

Next, when the driving operation of the apparatus main body is started, the belt 13 is driven and the pulley 9 rotates. The roller one-way clutch 8 locks when the pulley 9 rotates in the forward direction.
And the drum shaft 3 are integrally connected. Thereby, pulley 9
Are positioned by the drum shaft 3 and become independent from the encoder support frame 12. Therefore, the rotational vibration of the pulley 9 does not affect the encoder 19 via the encoder support frame 12. Temporarily pulley 9
It is difficult to say that the coupling between the taper shaft 15 and the drum shaft 3 is integral, and even if there is a slight displacement, the taper shaft 15 is driven by the drum shaft 3, so that the driving unit as shown in FIG. The encoder 19 can rotate in synchronization with the rotation of the image carrier 1 without being affected by the precision of the image carrier 1.

Next, the function of the presser spring 28 shown in FIGS. 3A and 3B when the process unit 5 is mounted on the apparatus main body will be described. When the drum shaft 3 penetrates the roller one-way clutch 8 and presses the taper shaft 15, the friction generated between the roller one-way clutch 8 and the drum shaft 3 and the retraction of the taper shaft 15 causes the taper shaft 15 and the bearing 17 to move between the taper shaft 15 and the bearing 17. Encoder support frame 12
Is pushed to the encoder 19 side. When the encoder support frame 12 withstands this pressing force, the drum shaft 3 penetrates the roller one-way clutch 8 and the taper shaft 15
By pressing, the spring 14 can be deflected. The pressing spring 28 generates a force that withstands the pressing force on the encoder support frame 12.

That is, in the configuration shown in FIG. 3A, the encoder support frame 12 is
In the configuration shown in FIG. 3B, the encoder supporting frame 12 is pressed against the seat 30 by a pressing spring 28. The frictional force generated between the step surface 27a or the seat body 30 and the encoder support frame 12 restricts the movement of the encoder support frame 12 corresponding to the mounting play around the drum shaft 3.

Next, an operation of removing the process unit 5 from the apparatus main body will be described. The roller one-way clutch 8 does not generate a force for locking the drum shaft 3 when the pulley 9 is at rest. Therefore, by withdrawing and retracting the process unit 5, the drum shaft 3 also retracts. When the drum shaft 3 is retracted, the taper shaft 15 moves together with the drum shaft 3 by the spring force of the spring 14. When the distal end fitting portion 15a of the tapered shaft 15 comes into contact with the pulley 9, the pulley 9 is also pushed through the tapered shaft 15 by the spring force of the spring 14, and is moved toward the apparatus body frame 6, but the pulley 9 is slightly moved. The end face of the device body frame 9 on the side of the device body frame comes into contact with the nylon sheet 7 provided on the device body frame 6, and the movement is regulated. By regulating the movement of the pulley 9, the movement of the taper shaft 15 is also regulated. When the process unit 5 is removed from the apparatus main body, the image carrier driving unit and the encoder
19 is maintained in the state described above.

FIG. 5A is a schematic sectional view showing a second embodiment of the present invention. Explaining the structure different from that of the first embodiment, the driving member for driving the image carrier 1 is attached to the apparatus main body in the first embodiment shown in FIG. In FIG. 1, a gear A32 for driving the image carrier 1 is mounted on the drum shaft 3 and provided on the process unit 5 side. In this case, the transmission of the driving force from the apparatus body side includes a gear B33 meshing with the gear A32 supported by the swing bracket 35, as shown in FIG.
This is performed by a gear C34 that meshes with the gear B33. The swing bracket 35 is rotatably supported around the central axis of the gear C34, and is urged by a spring 36 so that the gear B33 meshes with the gear A32. At this time, the position of the fulcrum of the swing bracket 35 is determined by the moment generated by the engagement.
A32 and gear B33 need to be set so as to push each other. As shown in FIG. 5 (C), a ring is provided near each of the gears A32 and B33 so that even if the gears A32 and B33 receive the biasing force in the direction of biting, the center distance is maintained correctly. It is common to provide 32a and 33a.

In the present embodiment, the swing bracket 35 that supports the gear, which is the drive unit of the apparatus body, is swingably supported because the dimensions of the image carrier 1 and the drive unit on the apparatus body side are due to errors in parts and the like. Because it is not constant. If the dimensional accuracy of the image carrier 1 is secured by a common positioning member with the drive unit on the apparatus main body side, the gear B33 configured to swing is fixed to the apparatus main body frame 6. May be.

In each of the above embodiments, the tapered portion 3a is provided at the tip of the drum shaft 3, and the tapered fitting portion 15a for fitting the tapered portion 3a is formed at the tip of the tapered shaft 15. Conversely, as shown in FIG.
May be formed such that a tapered fitting portion 3b is formed at the tip of the tapered shaft, and the tip tapered portion 15d of the tapered shaft 15 is fitted into the tapered fitting portion 3b.

The configuration of the connecting portion between the image carrier 1 and the encoder 19 is as follows.
The present invention is not limited to the configuration using the tapered member shown in each of the above embodiments. For example, as shown in FIG. 7, a protrusion 3c formed on the end surface of the tapered shaft 15 is formed in a concave portion 3c formed in the front end surface of the drum shaft 3.
15e may be inserted, and any configuration can be used as long as it is positioned coaxially and can obtain a frictional force necessary to drive the encoder 19.

〔The invention's effect〕

As described above with reference to the embodiments, according to the present invention, the rotation of the image carrier can be detected by the encoder with high accuracy, and the image carrier replacement work can be performed without requiring the encoder replacement work. And an image forming apparatus capable of easily performing the above.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention, and FIG.
FIGS. 3A and 3B are perspective views of an encoder support frame and an encoder portion, and FIGS. 3A and 3B are cross-sectional views showing mounting portions of the device body frame and the encoder support frame.
FIG. 4 is a plan view of an encoder support frame, FIG. 5A is a schematic sectional view showing a second embodiment of the present invention, and FIG.
FIG. 5B is a plan view showing the driving unit, and FIG.
Is a side view showing a gear portion of the drive unit, FIGS. 6 and 7 are diagrams showing a modification of the engagement portion between the drum shaft and the tapered shaft,
8 to 10 are schematic cross-sectional views showing a configuration example of a conventional image forming apparatus. In the figure, 1 is an image carrier, 2 is a flange, 3 is a drum shaft, 5 is a process unit, 6 is an apparatus body frame, 8
Is a roller one-way clutch, 9 is a pulley, 10 is a stopper, 11 is a bearing, 12 is an encoder support frame, 13
Is a belt, 14 is a spring, 15 is a tapered shaft, 17 is a bearing,
Reference numeral 18 denotes a bracket, 19 denotes an encoder, 27 denotes a shaft, 28 denotes a pressing spring, 29 denotes a cup screw, 30 denotes a seat body, 31 denotes a step screw, and 35 denotes a swing bracket.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-85763 (JP, A) JP-A-61-71316 (JP, A) JP-A-60-321 (JP, A) JP-A Sho 2- 282272 (JP, A) Japanese Utility Model 1-169344 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/00 550 G03G 21/14-21/18 G03G 21/00 370-540 G03G 15/00 303 B41J 11/11-11/70 G03G 21/00 350-352

Claims (4)

(57) [Claims] An image forming apparatus that detects rotation of an image carrier and forms an operation timing based on the detection signal, the image carrier having a rotation shaft that is detachably provided in the apparatus main body, and a rotation detector. An encoder having an encoder shaft for rotation, a support frame rotatably supporting the encoder shaft and movably provided in the apparatus main body, a joining portion formed on a rotation shaft of the image carrier, and an encoder shaft. Formed at the end, having a joint that positions the encoder shaft coaxially with the rotating shaft by joining to the joint of the rotating shaft,
The encoder shaft is positioned coaxially with respect to the rotating shaft by joining the joint of the rotating shaft and the joining portion of the encoder shaft when the image carrier is mounted on the apparatus main body. An image forming apparatus comprising: 2. An image forming apparatus according to claim 1, wherein said support frame is provided with an urging means for urging said encoder shaft in the direction of said joint. 3. The image forming apparatus according to claim 1, wherein a joining surface of the rotating shaft of the image bearing member and a joining portion of the encoder shaft are formed as tapered surfaces. . 4. A driving member is rotatably and loosely fitted to the support frame, and the driving member has a one-way clutch, and is driven by fitting a rotation shaft of the image carrier to the one-way clutch. The image forming apparatus according to claim 1, wherein the member is positioned.