JPH045667A - Image forming device - Google Patents

Abstract

PURPOSE:To detect the rotation of an image carrier with high precision by positioning an encoder shaft coaxially with respect to a rotary shaft by means of the joining of the joining parts of the rotary shaft and the encoder shaft when the image carrier is mounted on a main body. CONSTITUTION:When the driving action of the main body is started, a belt 13 is driven, and a pulley 9 is rotated. When the pulley 9 is rotated forward, a roller one-way clutch 8 is locked and the pulley 9 and a drum shaft 3 are integrally coupled. Thus, the pulley 9 is positioned by the shaft 3, and is independent of an encoder supporting frame 12. Therefore, the rotary vibration of the pulley 9 does not influence on an encoder 19 via the frame 12. Even if the coupling of the pulley 9 and shaft 3 is not completely integrated and a deviation slightly occurs, a taper shaft 15 is driven by the shaft 3, so that the encoder 19 can be rotated in synchronization with the rotation of the image carrier 1 without giving an influence to the precision of a driving part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus in which rotation of an image bearing member is detected by an encoder to form operation timing.

[Conventional technology]

Generally, in an image forming apparatus using an electrophotographic method or an electrostatic recording method, a drum-shaped image carrier is usually used. The electrostatic latent image on the image carrier is formed by synchronizing the moving speed of the image carrier and the writing means. As synchronization methods, there are two methods: one is to improve the rotation accuracy of the image carrier and print at a constant timing, and the other is to detect the rotation of the image carrier with an encoder and print based on the output signal.

The present invention relates to an image forming apparatus using the latter method of printing based on a detection signal of an encoder. Examples of the conventional configuration of an image forming apparatus using this method are shown in FIGS.
This will be explained using figures. The configuration example shown in FIG. 8 is constructed by integrally attaching an image carrier and an encoder, and a flange 2 is press-fitted or screwed into the end face of the image carrier 1. Flange 2 is bearing 4.
It is positioned and fixed to the apparatus main body frame (side plate) 6 via the housing 20. Further, the flange 2 is provided with a gear A2 that meshes with a gear of the drive system on the device main body side (not shown).
1 is attached. An encoder 19 that detects the rotational speed (or rotational fluctuation) of the image carrier 1 is attached to the end of the flange 2 of the image carrier 1 coaxially with the image carrier 1, and the encoder body is connected to the apparatus body by a bracket 18. It is configured to be fixed to the frame 6.

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

In the configuration example shown in FIG. 10, similar to the configuration example shown in FIG. Configured to be installed. In FIG. 10, 22 is a sleeve attached to the device body frame 6 that supports the shaft 25, 23 is a bearing of the shaft 25 fixed to a gear bracket 26 fixed to the device body frame 6, and 24 is a gear A21. This is a gear B fixed to the shaft 25 to be engaged.

(Problems to be Solved by the Invention) Incidentally, in the conventional configuration example shown in FIG. 8 above, since the image carrier 1 and the encoder 19 are integrally attached, high rotation detection accuracy can be obtained. However, since the encoder 19 is attached to the main body frame 6 of the apparatus, there are many parts of the apparatus that must be disassembled during maintenance work such as replacing the image carrier 1, and the structure is not highly maintainable.
Replacement work by general users is not possible.

In addition, in the configuration example shown in Part 9, the process unit 5 is configured so that it can be attached to and detached from the main body of the apparatus.
The work of attaching and detaching the process unit 5, which involves replacing consumable parts, can be done by a general user, and the detection accuracy of the encoder 19 is as high as that of the conventional example shown in FIG. However, this configuration has the disadvantage that the expensive encoder 19 must be replaced at the same time each time the process unit 5 is replaced, which increases the cost of the process unit 5.

Costs can be reduced by replacing the encoder 19 when replacing the process unit 5, but it cannot be expected that the -a user will replace the encoder 19, and the work will be done by a service person, and maintainability for general users will not be ensured.

Furthermore, in the configuration example shown in FIG. 1O, the encoder 19
Since the encoder 19 is attached to the drive system of the main body of the apparatus, even if the process unit 5 is replaced, there is no need to replace the encoder 19 at the same time, and there is no need to perform installation or replacement work. However, a drawback of this conventional example is that what the encoder 19 detects is not the rotation of the image carrier 1, but the rotation of the drive system placed near the image carrier 1, and the rotation includes the effects of backlash etc. The point is that it detects. This causes a problem in that the image carrier 1 and the latent image writing means are not completely synchronized, which adversely affects the quality of the printed image.

The present invention has been made to solve the above-mentioned problems in conventional image forming apparatuses, and makes it possible to detect the rotation of an image carrier with high accuracy without compromising the user's ability to maintain the image. The purpose of the present invention is to provide an image forming apparatus.

[Means and effects for solving the problems] In order to solve the above problems, an image forming apparatus according to the present invention detects rotation of an image carrier and forms an operation timing based on the detection signal. The apparatus includes: an image carrier that is removably attached to the apparatus body and has a rotating shaft; an encoder that has an encoder shaft for rotation detection; and an encoder that rotatably supports the encoder axis and is freely movable on the apparatus body. A support frame, a joint formed on the rotation shaft of the image carrier, and an end of the encoder shaft are formed, and the encoder shaft is positioned coaxially with the rotation shaft by joining to the joint of the rotation shaft. a joint part, and when the image carrier is attached to the apparatus main body, the joint part of the rotary shaft and the joint part of the encoder shaft are joined, so that the encoder shaft is positioned coaxially with respect to the rotary shaft. It is configured so that

With this configuration, the image carrier is removably attached to the device body, and the encoder is supported by a support frame freely movable in the device body, so there is no need to replace the encoder. Therefore, the image carrier can be replaced easily. Furthermore, when the image carrier is attached to the main body of the apparatus, 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 the rotation of the image carrier is increased by the encoder. It becomes possible to detect with high precision.

〔Example〕

Examples will be described below. FIG. 1 is a schematic sectional view showing a first embodiment of an image forming apparatus according to the present invention, and the same or equivalent members as those of the conventional example shown in FIGS. 8 to 10 are given the same reference numerals. It is shown as follows. 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 its tip is press-fitted into the flange 2. The image carrier 1 to which the flange 2 and 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 is composed of a plurality of process elements such as a cleaning member and a static eliminating member.

Next, the configuration of the device main body side will be explained. 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 12a.

The bearing 17 supports a tapered shaft 15 having a tapered shape that fits into the tapered portion 3a of the drum shaft 3 so as to be slidable in the axial direction, and the other end of the tapered shaft 15 15b is encoder support frame 1
It is arranged so as to protrude from the opening of the second cylindrical housing 12a. Further, the tapered shaft 15 is urged in the direction of the drum shaft 3 by a spring 14 disposed between a nylon seam 6 serving as a spring receiver that contacts the end surface of the bearing 17 and a stepped portion 15c of the tapered shaft 15. It has become so.

A shaft portion 19a of an encoder 19 is coaxially attached to the other end 15b of the tapered shaft 15, and a bracket 18 is fixed to the main body of the encoder 19, as shown in FIG. A notch recess 18a is formed at the other bent end of the encoder support frame 12. Thus, the encoder 19 is supported by the bracket 18 so that its movement in the rotational direction with respect to the shaft is restricted, but it is free from movement in the axial direction indicated by the arrow.

That is, when the tapered shaft 15 slides in the axial direction, the encoder 19 also slides together.

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 bell 3 is engaged. Further, a boss portion 9a is formed on the pulley 9, and a bearing 11 is press-fitted into this boss portion 9a. The outer ring of the bearing 11 is attached to the peripheral wall of the inner step of the housing 12a of the encoder support frame 12.
It is installed with some play. Also, pulley 9 is
A stopper 10 protruding from the opening of the housing 12a of the encoder support frame 12 prevents it from coming off the encoder support frame 12 via the bearing 11.

The encoder support frame 12 and the apparatus body frame 6 are attached as shown in FIG. 3 (8) or (3).

That is, first, as shown in the third diagram, a hole 12 formed in the encoder support frame 12 is inserted into the main body frame 6.
A shaft 27 having a stepped surface 27a having a diameter d smaller than the diameter c is fixed, and the encoder support frame 12 is attached to the shaft 27.
The encoder support frame 12 is held on the apparatus main body frame 6 by inserting the cup screw 29 into the shaft 27 via the presser spring 28. Alternatively, as shown in FIG. 3 (Bl), a seat 30 with a threaded portion is attached to the device main body frame 6, the hole 12c of the encoder support frame 12 is brought into contact with the seat 30, and the presser spring 28 is tightened. A stepped screw 31 having a diameter d smaller than the diameter of the hole 12c is attached to the seat body 30 through the hole 12c, so that the encoder support frame 12 is supported by the apparatus main body frame 6. As shown in FIG. 4, the hole 12c is provided at three locations, and is supported at three locations by the cup screw 29 or step screw 31 via the presser spring 28 as described above. It is freely supported with respect to the apparatus main body frame 6 by the amount of play between it and 31.

Next, the mounting operation and driving operation of the process unit 5 to the apparatus main body in the image forming apparatus configured as described above will be explained. The process unit 5 including the image carrier 1 is inserted into the apparatus main body while being guided by a guide member (not shown) on the apparatus main body side. At this time, as the process unit 5 is inserted, the drum shaft 3 passes through a hole 6a provided in the apparatus main body frame 6, passes through a roller one-way clutch 8 provided in the pulley 9, and connects the tapered shaft 15 with the spring 1.
4 and press against the encoder 19 side.

At this time, the boss portion 5a of the process unit 5 is inserted into the positioning hole portion 6b of the apparatus body frame 6, and the tapered portion 3a of the drum shaft 3 and the tip fitting portion 15a of the tapered shaft 15 are fitted. As a result, the process unit 5 is positioned and fixed relative to the apparatus main body frame 6, and the position of the image carrier 1 relative to the apparatus main body is determined.

At this time, the drive pulley 9 and encoder 19 on the apparatus main body side that drive the image carrier 1 are attached to the apparatus main body frame 6 with some play and are configured to be slightly movable. As the drum shaft 3 is inserted coaxially with the image carrier 1, it is positioned coaxially with the image carrier 1. Further, the drum shaft 3 and the tapered shaft 15 are brought into pressure contact by the pressing force applied by the spring 14, and sufficient frictional force is generated to rotate the encoder 19, so that the rotation of the image carrier 1 is reliably transmitted to the encoder 19. That will happen.

Next, when the driving operation of the main body of the apparatus starts, the heald 13 is driven and the pulley 9 is rotated. The roller one-way clutch 8 locks when the pulley 9 rotates in the forward direction.
and the drum shaft 3 are integrally connected. This allows pulley 9
is positioned by the drum shaft 3 and becomes independent from the encoder support frame 12. Therefore, pulley 9
The rotational vibration of the encoder 19 is prevented from affecting the encoder 19 via the encoder support frame 12. Even if the connection between the pulley 9 and the drum shaft 3 is not integral, and there is some misalignment, the taper shaft 15 is driven by the drum shaft 3, so as in the conventional example shown in FIG. The encoder 19 can rotate in synchronization with the rotation of the image carrier 1 without being affected by the accuracy of the drive unit.

Next, the function of the presser spring 2B shown in (2) in FIG. 3 when the process unit 5 is attached to the main body of the apparatus will be explained. When the drum shaft 3 passes through the roller one-way clutch 8 and presses the tapered shaft 15, friction occurs between the roller one-way flange 8 and the drum shaft 3, and the tapered shaft 15 retreats, causing a gap between the tapered shaft 15 and the bearing 17. The encoder support frame 12 is pushed toward the encoder 19 by the frictional force generated. By withstanding this pressing force by the encoder support frame 12, the drum shaft 3 can pass through the roller one-way flange 8, push the tapered shaft 15, and bend the spring 14.

The presser spring 28 generates a force against the encoder support frame 12 to withstand the above-mentioned pressing force.

That is, in the configuration shown in the third diagram, the encoder support frame 12 is held against the shaft 27 by the presser spring 28.
Moreover, in the structure shown in FIG. Due to the frictional force generated between the stepped surface 27a or the seat body 30 and the encoder support frame 12,
When the encoder support frame 12 is mounted around the drum shaft 3, movement due to backlash is restricted.

Next, the operation of removing the process unit 5 from the apparatus main body will be explained. The roller one-way clutch 8 does not generate any force to lock the drum shaft 3 when the pulley 9 is in a stationary state. Therefore, by pulling out and retracting the process unit 5, the drum shaft 3 is also retracted. When the drum shaft 3 is retracted, the tapered shaft 15 moves together with the drum shaft 3 due to the spring force of the spring 14. When the tip fitting portion 15a of the tapered shaft 15 comes into contact with the pulley 9, the pulley 9 is also pushed via the tapered shaft 15 by the spring force of the spring 14 and is moved toward the device main body frame 6, but with a slight movement, the pulley 9 9 on the device body frame side, the device body frame 6
The movement is regulated by contacting the nylon sheet 7 provided on the nylon sheet 7 . By restricting the movement of the pulley 9, the movement of the tapered shaft 15 is also restricted. When the process unit 5 is removed from the apparatus main body, the image carrier driving section and the encoder 19 are maintained in the above state.

FIG. 58 is a schematic sectional view showing a second embodiment of the present invention. To explain the structure that is different from the first embodiment described above, the driving member for driving the image carrier 1 was attached to the main body of the apparatus in the first embodiment shown in FIG. Here, 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 driving force is transmitted from the device main body side to the gear B33 which meshes with the gear A32 supported by the swing bracket 35, as shown in FIG. 5 FB+.
This is performed by gear C34 that meshes with gear B33. The swing bracket 35 is rotatably supported about the central axis of the gear C34 as a fulcrum, and is biased 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 such that the moment generated by the engagement is between the gears A32 and B3.
It is necessary to set it so that 3 are pushed together.

Note that even if gear A32 and gear B33 receive an urging force in the direction of biting, the distance between the shafts is maintained correctly, as shown in Fig. 5 (
As shown in C), it is common to provide rings 32a and 33a near gear A32 and gear B33, respectively.

In this embodiment, the reason why the swinging bracket 35 supporting the gear, which is the driving part of the apparatus main body, is swingably supported is because the dimensions of the image carrier 1 and the driving part on the apparatus main body side are different from each other due to errors in parts, etc. This is because it is not constant. If the dimensional accuracy of the image carrier 1 and the drive unit on the apparatus main body side is guaranteed by a common positioning member, then the gear B33 configured to swing can be fixed to the apparatus main body frame 6. You may.

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 into which the tapered portion 3a is fitted is formed at the tip of the tapered shaft 15. Conversely, as shown in FIG. 6, a tapered fitting part 3b may be formed at the tip of the drum shaft 3, and the tip tapered part 15d of the tapered shaft 15 may be fitted into this.

Furthermore, the configuration of the connecting portion between the image carrier l and the encoder 19 is as follows:
In addition to the configuration using the tapered member shown in each of the above embodiments, for example, as shown in FIG. Any configuration can be used as long as it is coaxially positioned and provides the frictional force necessary to drive the encoder 19.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, it is possible to detect the rotation of the image carrier with high precision using an encoder, and moreover, it is possible to detect the rotation of the image carrier with high precision without the need for replacing the encoder. It is possible to provide an image forming apparatus that allows easy replacement work.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention;
The figure is a perspective view of the encoder support frame and the encoder part, and Fig. 3 is a sectional view showing the installation part of the device body frame and the encoder support frame. Fig. 4 is a plan view of the encoder support frame. Figure 5 is a schematic sectional view showing the second embodiment of the present invention.
FIG. 5 is a plan view showing the drive section; FIG. 5 is a side view showing the gear portion of the drive section; FIGS. Figures 8 to 10
The figure is a schematic cross-sectional view showing an example of the configuration 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, and 8
1 is a roller one-way clutch, 9 is a pulley, 10 is a stopper, 11 is a hair ring, 12 is an encoder support frame, 13 is a belt, 14 is a spring, 15 is a tapered shaft, 17
is a hair ring, 18 is a bracket, 19 is an encoder,
27 is the shaft, 28 is the presser spring, 29 is the cup screw, 30
31 is a step screw, and 35 is a swing bracket. Patent applicant: Olympus Optical Industry Co., Ltd. Figure 2 Figure 4 Figure 3 (A) Figure 5 (B) (C) b Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. In an image forming apparatus that detects the rotation of an image carrier and forms operation timing based on the detection signal, an image carrier that is detachably installed in the apparatus main body and has a rotation axis; , an encoder having an encoder shaft for rotation detection, a support frame rotatably supporting the encoder shaft and freely movably provided in the apparatus main body, a joint formed on the rotation shaft of the image carrier, and the a joint part formed at an end of the encoder shaft and positioning the encoder shaft coaxially with the rotary shaft by joining to the joint part of the rotary shaft, when the image carrier is mounted on the apparatus main body. An image forming apparatus characterized in that the encoder shaft is positioned coaxially with respect to the rotation shaft by joining the joint portion of the rotation shaft and the joint portion of the encoder shaft. 2. The image forming apparatus according to claim 1, wherein the support frame is provided with biasing means for biasing the encoder shaft in the direction of the joint. 3. The image forming apparatus according to claim 1 or 2, wherein a joint surface of the joint portion of the rotating shaft of the image carrier and the joint portion of the encoder shaft is formed as a tapered surface. 4. A driving member is rotatably fitted into the support frame, and the driving member has a one-way clutch, and the driving member is positioned by fitting the rotating shaft of the image carrier to the one-way clutch. The image forming apparatus according to any one of claims 1 to 3, characterized in that the image forming apparatus is configured such that the image forming apparatus is configured to perform the following operations.