JP2021092641A - Image formation apparatus - Google Patents

Abstract

To solve a problem due to the occurrence of a bending moment in an LED head when biasing means such as a spring is directly biased to the LED head in a case where the LED head is biased to a photoreceptor drum.SOLUTION: An image formation apparatus comprises: an LED head 57 which has a contact protrusion 153; an LED head holder 40; and a development unit 51 which has a photoreceptor drum 52 and a spacer 161 on which the LED head 57 is placed. The LED head holder 40 comprises: a link arm 42 which is engaged with the LED head 57 to hold the LED head; a coil spring 43 which biases the link arm; and regulation parts (103, 125) which regulate the movement of the link arm 42. In such a stage that an upper cover 35 is closed, the contact protrusion 153 is brought into pressure-contact with the spacer 161.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus, and more particularly to a configuration of an LED head holding mechanism for holding an LED head.

Conventionally, when the LED head is urged to a predetermined position with respect to the photoconductor drum, some urging means such as a spring directly urges the LED head (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-145648 (page 6, FIG. 1)

However, in the conventional configuration, since the bending moment is generated in the long LED head by the urging means, it is necessary to take measures leading to cost increase such as increasing the rigidity of the LED head in order to prevent the deterioration of the image quality due to this. Met.

The image forming apparatus according to the present invention
The exposure is caused by the contact between the exposure head portion provided with the contact portion, the head holding portion that holds the exposure head portion, the holding member that holds the head holding portion, the image carrier, and the contact portion. It has an image forming unit provided with a mounting portion on which the head portion is mounted, and has.
The head holding portion is
A displacement member that is displaceably held with respect to the head holding portion main body and engages with the exposure head portion to hold the exposure head portion, an urging member that urges the displacement member in one direction, and the displacement. It is equipped with a regulating unit that regulates the movement of the member in one direction beyond a predetermined position.
When the exposure head portion is placed on the above-described mounting portion and the holding member moves,
The displacement member is separated from the predetermined position against the bias.

According to the present invention, since the bending moment generated in the exposure head portion can be suppressed by the urging force of the urging member, deterioration of the image quality due to the bending moment can be prevented without increasing the rigidity of the exposure head portion more than necessary.

It is a main part block diagram which shows the main part structure of the image forming apparatus of Embodiment 1 based on this invention. FIG. 5 is an external perspective view of an LED unit including an LED head and an LED head holder viewed from diagonally above with the direction of arrow A shown in FIG. 1 as a common direction. FIG. 2 is a front view of the LED unit shown in FIG. 2 as viewed from the direction of arrow A. It is a front view which looked at the LED unit in the mounted state corresponding to the state at the time of a printing operation from the direction of arrow A. FIG. 4 is a cross-sectional view of the LED unit shown in FIG. 4, which includes a front side urging protrusion and a rear side urging protrusion, as viewed from the direction of arrow C. FIG. 3 is a partially enlarged view of the vicinity of the right end portion of the LED unit in FIG. FIG. 4 is a partially enlarged view of the vicinity of the right end portion of the LED unit in FIG. FIG. 5 is an external perspective view of the LED unit of the second embodiment when viewed from diagonally above with the direction of arrow A shown in FIG. 1 as a common direction. FIG. 8 is a front view of the LED unit shown in FIG. 8 as viewed from the direction of arrow A. 9 is a cross-sectional view of the LED unit shown in FIG. 9 including a front side urging protrusion and a rear side urging protrusion as viewed from the direction of arrow C. It is a partial enlarged view near the right end portion of the LED unit in the mounted state corresponding to the state at the time of printing operation.

Embodiment 1.
FIG. 1 is a main part configuration diagram showing a main part configuration of the image forming apparatus of the first embodiment based on the present invention.

As shown in the figure, the image forming apparatus 1 includes, for example, a configuration as a tandem type color electrophotographic printer, and the paper feed cassette 10 is loaded with recording paper as a recording medium in the image forming apparatus 1. It is attached detachably. The pickup roller 21 constitutes a paper feed unit 20 together with a paper feed roller 22 and a separation roller 23 arranged in pairs in contact with each other. The pickup roller 21 and the paper feed roller 22 are rotationally driven by a rotary drive means (not shown), and the separation roller 23 generates torque in the counter-rotation direction by a torque generating means (not shown).

Therefore, the pickup roller 21 pulls out the uppermost recording paper that comes into contact with the paper cassette 10, and the paper feed roller 22 and the separation roller 23 may be used even when, for example, a plurality of recording papers are pulled out at the same time. This recording paper is sequentially fed to the transport path one by one.

A resist roller 31 and a transport roller 32 are arranged in this order on the transport path on the downstream side of the paper feed unit 20 in the transport direction of the recording paper (indicated by the dotted arrow). The resist roller 31 is paired with the accompanying pressure roller 33 that pressurizes the resist roller 31 to generate a conveying force, and the conveying roller 32 pressurizes the conveying roller 32 to generate a conveying force. It is paired with 34. The roller pair of the resist roller 31 corrects the skew of the recording paper, and the roller pair of the transport roller 32 feeds the recording paper to the image forming portion.

The image forming unit is formed by a developing unit 51K, 51Y, 51M, 51C (referred to as 51 when it is not necessary to distinguish them) as four image forming units detachably arranged in series, and a developing unit 51. It is composed of a transfer unit 60 that transfers the developed toner to the upper surface of a recording paper by cloning force. The four developing units 51 arranged in series are all structurally the same, and the toner colors used are black (K), yellow (Y), magenta (M), and cyan (C). Only its operation timing is different. Here, in order from the upstream side in the paper transport direction, the development unit 51K for black (K), the development unit 51Y for yellow (Y), the development unit 51M for magenta (M), and the development unit for cyan (C). 51Cs are arranged.

Therefore, here, the internal configuration of the black (K) developing unit 51K will be described below as a representative.

The developing unit 51K is formed on the charged surface of the photoconductor drum 52K as an image carrier that supports toner development, a charging roller 53 that charges the surface of the photoconductor drum 52K, and an LED head 57K. A developing roller 54 that forms toner development by frictional charging on the electrostatic latent image, a toner supply roller 55 that supplies toner to the developing roller 54, and a cleaning blade 56 that scrapes off residual toner remaining on the surface of the photoconductor drum 52K after transfer. And so on. Power is transmitted to the drums and rollers used in each developing unit 51 from a drive motor (not shown) via gears and the like.

The transfer unit 60 includes a transfer belt 61 that electrostatically attracts and conveys recording paper, a drive roller 62 that drives the transfer belt 61, a tension roller 63 that is paired with the drive roller 62 and stretches the transfer belt 61, and a developing unit. Each of the photoconductor drums 52K, 52Y, 52M, 52C of 51 (referred to as 52 when it is not necessary to distinguish them) is arranged so as to face each other and press contact with each other, and a voltage for transferring toner development to recording paper. The transfer rollers 67K, 67Y, 67M, 67C (referred to as 67 when it is not necessary to distinguish them) and the like are provided. The transport plane on which the transfer belt 61 conveys the recording paper may be hereinafter referred to as a reference plane.

The development unit 51 and the transfer belt 61 are driven in synchronization with each other, and the toner development of each color is sequentially superimposed and transferred on the recording paper electrostatically adsorbed on the transfer belt 61. The recording paper to which the toner development is transferred by the image forming unit in this way is sent to the fixing unit 70 that fuses the toner development to the recording paper by heat and pressure.

The fixing unit 70 includes a heating roller 71 provided with a heat source such as a heater and in contact with the recording paper from above, and a pressure roller 72 that rotates in a driven manner, and the heated heating roller 71 and the pressure roller 72 that are in pressure contact with the heated roller 71. The recording paper is heated and pressurized by transporting the recording paper to fix the toner image on the recording paper.

Discharge rollers 81 and 82 are sequentially arranged in the transport path on the downstream side of the fixing unit 70 in the transport direction of the recording paper, and the fixed recording paper discharged from the fixing unit 70 is conveyed along the path. , Discharge to the discharge tray 83.

On the other hand, in the case of double-sided printing on the recording paper, the path switching lever 90 feeds the recording paper discharged from the fixing unit 70 and fixed on one recording surface to the transfer roller 91 side, and the transfer roller 91 transfers the recording paper. Is sent to the double-sided transport unit 92.

In the double-sided transfer unit 92, the feeding recording paper is once drawn into the reversing lead-in path 97 by the reversing roller 93, and then by reversing the reversing roller 93, the rear end portion of the drawn recording paper is conveyed as the front end portion. It is fed to the roller 94, and further fed to the registration roller 31 again by the transport rollers 94, 95, 96. The recording paper fed to the resist roller 31 is fed to the image forming unit again with the other unprinted recording surface facing up, printed on the other recording surface in the same manner as one recording surface, and then ejected. It is discharged to the tray 83.

Here, the LED heads 57K, 57Y, 57M, 57C (referred to as 57 when it is not necessary to distinguish them) correspond to the corresponding LED head holders 40K, 40Y, 40M, 40C (when there is no particular need to distinguish them). Each LED head holder 40 is held by an upper cover 35 as a holding member. Further, the upper cover 35 is arranged in the vicinity of the discharge roller pair 82, and is rotated in the direction of arrow B with a rotation axis (not shown) extending in the rotation axis direction of the photoconductor drum 52 as a rotation center. The upper part of the forming device 1 is released from the closed state shown in FIG.

At this time, the LED head 57 held by the LED head holder 40 also moves together, and moves in a direction away from the mounting position of the corresponding developing unit 51. Here, the four LED heads 57 have the same configuration, and the four LED holders 40 also have the same configuration.

FIG. 2 is an external perspective view of the LED unit 39 including the LED head 57 and the LED head holder 40 with the arrow A direction shown in FIG. 1 as a common direction, as viewed from diagonally above. However, for convenience, the LED head 57 is shown here. Shows the state when the photoconductor drum 52 is separated from the mounting position shown in FIG.

FIG. 3 is a front view of the LED unit 39 shown in FIG. 2 as viewed from the direction of arrow A, and FIG. 4 shows a state in which the LED head 57 is mounted at the mounting position of the developing unit 51 (FIG. 1) and is in a printing operation. Corresponds to the front view of the LED unit 39 in the mounted state corresponding to the above, that is, the LED unit 39 of FIG. 1 as viewed from the direction of arrow A, and FIG. 5 shows the front side urging protrusion 105 and the rear of the LED unit 39 shown in FIG. FIG. 6 is a cross-sectional view of a cross section including the side urging protrusion 106 as viewed from the direction of arrow C, FIG. 6 is a partially enlarged view of the vicinity of the right end portion of the LED unit 39 in FIG. 3, and FIG. 7 is a partially enlarged view of the LED unit in FIG. It is a partial enlarged view near the right end portion of 39.

As shown in FIG. 2, when the LED unit 39 is viewed from the direction of arrow A, the top, bottom, left, right, front, and back may be specified. Further, the arrow A direction is parallel to the reference plane and corresponds to the direction in which the recording paper is conveyed by the transfer belt 61, and the arrow C direction corresponds to the direction parallel to the reference plane and orthogonal to the arrow A direction. Therefore, the reference plane and the rotation axis 65 (FIG. 4) of the photoconductor drum 52 are parallel, and the arrow C direction is parallel to the rotation axis 65.

Therefore, the LED unit 39 shown in FIGS. 2 and 3 shows a state when the upper cover 35 is closed with the developing unit 51 removed, for example, but the positional relationship between the LED head holder 40 and the LED head 57 is shown. In the above case, the LED unit 39 moves upward from the state shown in FIG. 4, and the LED head 57 corresponds to the state when the LED head 57 is separated from the mounting position.

As shown in FIG. 2, when the LED head holder 40 as the head holding portion has the LED head 57 as the exposure head portion in the mounting position shown in FIG. 4 in the vicinity of both ends in the longitudinal direction extending to the left and right. The left arm rotation shaft 41L and the right arm rotation shaft 41R are provided so as to be planted in a direction orthogonal to the rotation axis direction of the photoconductor drum 52 and parallel to the reference plane (parallel to the arrow A).

In the vicinity of the right end portion of the LED unit 39, the right arm rotation shaft 41R holds the right link arm 42R holding the right end portion of the LED head 57, and the right link arm 42R is urged by the right coil spring 43R. The LED head holding mechanism is provided, and the movement thereof is restricted. The LED head holding mechanism is the same in the vicinity of the left end portion of the LED unit 39, that is, both arm rotation shafts 41L in the longitudinal direction of the LED head holder 40. It is formed symmetrically with respect to the virtual center plane that intersects the arrow C direction at the center between 41Rs.

Therefore, here, the configuration of the LED head holding mechanism on the right side is mainly described, and at the end of the code of the members arranged symmetrically, for example, the left arm rotation shaft 41L and the right arm rotation shaft 41R are shown. (L) and (R) are added to the same number to distinguish left and right, and the description of the LED head holding mechanism on the left side is omitted, and when it is not necessary to distinguish left and right, these end signs are omitted. In some cases.

The right arm rotation shaft 41R is arranged from one side wall portion of the mechanism accommodating portion 45R formed near the right end of the LED head holder 40 in the upright direction at a height sufficient to fit in the accommodating portion, and serves as a displacement member. The right link arm 42R is rotatably held by the right arm rotation shaft 41R by mounting the rotation shaft hole on the right arm rotation shaft 41R. That is, the right link arm 42R is rotatably held by the main body of the LED head holder 40. For each component of the LED head holder 40, such as the right link arm 42R of the LED head holder 40, the portion excluding the component may be referred to as the LED head holder 40 main body.

The right link arm 42R has a rotation shaft hole at one end and hangs down at a right angle to the extension direction from the arm portion 101R extending in a direction away from the rotation center and the other end. The right head engaging portion 102R as the engaging portion is continuously formed in a substantially L shape.

The LED head holder 40 is arranged so as to sandwich the arm portion 101R in the front-rear direction at the other end of the arm portion 101R on which the right head engaging portion 102R hangs, as shown in the cross-sectional view of FIG. The front regulation surface 121R has a surface 121R and a rear regulation surface 122R, the front regulation surface 121R is provided with a front regulation guide elongated hole 125R into which the front regulation protrusion 103R formed on the arm portion 101R is fitted, and the rear regulation surface 122R is an arm portion. It is provided with a rear regulation guide elongated hole 126R into which the rear regulation protrusion 104R formed on the 101R is fitted. The front regulation protrusion 103 and the front regulation guide long hole 125, and the rear regulation protrusion 104 and the rear regulation guide long hole 126 correspond to the regulation portion.

As shown in the cross-sectional view of FIG. 5, the right coil spring 43R as an urging member is arranged in a compressed state between the LED head holder 40 main body and the right link arm 42R, and urges the right link arm 42R clockwise. doing. The right coil spring 43R is positioned and held by fitting a holding protrusion 127R formed on the LED head holder 40 at one end thereof, and the other end is arranged so as to press the upper flat portion 107R of the right link arm 42R. Has been done.

The right link arm 42R is urged clockwise by the right coil spring 43R, and as shown in FIG. 6, the front regulation protrusion fitted into the front regulation guide elongated hole 125R (rear regulation guide elongated hole 126R). The 103R (rear side regulation protrusion 104R) abuts on the lower end of the front side regulation guide elongated hole 125R (rear side regulation guide elongated hole 126R), and further clockwise rotation is restricted. At this time, the shape and arrangement of each portion are taken into consideration so that the extending direction of the arm portion 101R is a position slightly inclined downward with respect to the arrow C direction.

As shown in the cross-sectional view of FIG. 5, the right head engaging portion 102R of the right link arm 42R is formed by a pair of cylindrical front urging protrusions 105R and rear urging protrusions 106R protruding forward and backward at the lower tip portion. Has been done. The front side urging protrusion 105R and the rear side urging protrusion 106R correspond to the protrusions.

On the other hand, as shown in FIG. 2, the LED head 57 is held by the LED head holder 40 in the vicinity of both ends in the longitudinal direction extending to the left and right. Here, the right end portion will be described as an example, but the front urging projection 105R of the right head engaging portion 102R is located on the upper portion of the LED head 57 at a position facing the right head engaging portion 102R of the right link arm 42R. Anterior engaging elongated hole 151R and a posterior engaging elongated hole 152R into which the rear urging projection 106R is fitted are formed. The front engaging slot 151R and the rear engaging slot 152R correspond to the fitting holes.

As shown in FIG. 7, in the front engaging slot 151R and the rear engaging slot 152R, the LED head 57 is mounted at the mounting position of the development unit 51 (FIG. 1) as described later, and the printing operation is performed. In the mounting state corresponding to the case, the lower edge portions 155R and 156R extending in the direction of arrow C, which is the longitudinal direction of the LED head 57, and abutting at least the front and rear urging protrusions 105 and 106 are the reference planes. It is formed in parallel.

As shown in FIGS. 5 and 7, at a predetermined position on the lower surface of the LED head 57, an abutting protrusion as an abutting portion that abuts on the right spacer 161R as a mounting portion formed on the developing unit 51 described later. 153R is arranged. The contact protrusion 153R is located substantially at the center of the LED head 57 in the thickness direction (arrow A direction), and the LED head 57 is mounted at the mounting position of the development unit 51 (FIG. 1), which corresponds to the printing operation. Assuming a plane perpendicular to the arrow C direction in the mounting state, the central portion thereof is located on the same plane as the central portion in each longitudinal direction of the front engaging slot 151R and the rear engaging slot 152R. It is arranged like this.

As shown in FIG. 5, in the right head engaging portion 102R of the link arm 42, the central portion thereof, the front movable portion 111R including the front urging protrusion 105R, and the rear movable portion including the rear urging protrusion 106R. The 112R is divided by L-shaped grooves 113R and 114R formed in an L-shaped cross section except for the lower end portion.

As a result, when the LED head 57 is attached to or removed from the LED head holder 40, the operator strongly grasps the upper parts of the front movable portion 111R and the rear movable portion 112R from the front and back and bends them. As a result, the front side urging protrusion 105R and the rear side urging protrusion 106R can be easily inserted into or removed from the front side engaging elongated hole 151R and the rear side engaging elongated hole 152R.

The configuration of the LED head holding mechanism near the right end of the LED unit 39 has been described above. However, the LED head holding mechanism near the left end formed symmetrically with this has the same number as the corresponding portion in each drawing. (L) is added to the end of the above, and detailed description thereof will be omitted.

In the above configuration, the LED head 57 is mounted from a state in which the LED head 57 is separated from the mounting position of the developing unit 51 (FIG. 1) (hereinafter, may be referred to as a separated state) as the upper cover 35 rotates. The operation of the LED head holding mechanism of the LED unit 39 when the LED unit 39 is mounted at a position and displaced to a mounted state corresponding to the state at the time of printing operation will be described.

3 and 6 show the state of the LED unit 39 when it is in the separated state. At this time, the arm portion 101 is urged by the coil spring 43, and the front regulation protrusion 103 (rear regulation projection 104) thereof is the front regulation guide elongated hole 125 (rear side) of the front regulation surface 121 (rear regulation surface 122). It is in contact with the lower end of the regulation guide elongated hole 126), and further rotation is restricted. The front urging projection 105 (rear urging projection 106) that fits into the front engaging elongated hole 151 (rear engaging elongated hole 152) of the LED head 57 is the front engaging elongated hole 151 (rear engaging elongated hole). The LED head 57 is held by the LED head holder 40 by abutting on the upper side portion of 152).

Therefore, since no load is applied to the LED head 57 in the longitudinal direction in this separated state, a bending moment is not generated by the urging force of the coil spring 43.

From this state, when the LED head 57 approaches the mounting surface 51a (FIG. 7) of the developing unit 51 (FIG. 1) as the upper cover 35 rotates, the contact projection 153 first mounts the developing unit 51. The distance between the mounting surface 51a of the developing unit 51 and the LED head 57 is determined by abutting against the spacer 161 formed at the corresponding position on the mounting surface 51a, and at the same time, the front, rear, left and right positions are also determined by positioning means (not shown). Be done.

Further, when the upper cover 35 rotates in the closing direction, only the LED head holder 40 moves further downward without the LED head 57 being displaced, so that the link arm 42 rotates (counterclockwise in the case of 42R). Direction, clockwise in the case of 42L), as shown in FIG. 7, the front regulation protrusion 103 (rear regulation protrusion 104) is the lower end portion of the front regulation guide elongated hole 125 (rear regulation guide elongated hole 126). The separated state is maintained when the upper cover 35 is closed.

At this time, as shown in FIG. 7, the arm portion 101R of the link arm 42 is substantially parallel to the reference plane, and the front side urging protrusion 105 (rear side urging protrusion 106) is formed by the front side engaging elongated hole 151 (rear side). The lower edge portion 155 (156), which is located at the center of the engaging elongated hole 152) in the longitudinal direction and is formed parallel to the reference plane by receiving the urging force of the coil spring 43, is downwardly perpendicular to the reference plane. Press on.

Therefore, the LED head 57 is in a state where the contact projection 153 is in pressure contact with the spacer 161 of the developing unit 51 at a position at a predetermined distance from the mounting surface 51a of the developing unit 51, and is placed at the mounting position of the developing unit 51. It will be placed in a stable state.

At this time, the position (engagement location) where the front side urging protrusion 105 (rear side urging protrusion 106) abuts (engages) with the lower edge portion 155 (156) and presses the contact protrusion 153. Assuming that the center position of the pressure contact portion (pressure contact location) that is in pressure contact with the spacer 161 of the development unit 51 is perpendicular to the arrow C direction (the axial direction of the rotation axis 65 of the photoconductor drum 52), the same virtual plane is assumed. The pressing direction of the pressing force F, which is located on P and the anterior urging projection 105 (rear urging projection 106) presses the lower edge portion 155 (156), is parallel to this virtual plane P. There is.

Therefore, in the state where the LED head 57 is in the mounting state corresponding to the printing operation and is pressed against the developing unit 51 by the coil spring 43, the pressing force F is applied to the developing unit 51 without deriving a component force. It can be transmitted to the spacer 161.

Further, here, since the coil spring 43 is urged to the link arm 42 in a substantially virtual plane P, it is possible to prevent a bending moment from being generated in the arm portion 101 of the link arm 42.

According to the present embodiment, the coil spring 43 is used as a means for urging the link arm 42, but the present invention is not limited to this, and for example, the link arm 42 is arranged on the arm rotation shaft 41 and the LED head holder is used. Various modes can be taken, such as adopting a torsion spring spanned between the 40 main body and the arm portion 101 of the link arm 42.

As described above, according to the image forming apparatus of the present embodiment, when the LED head 57 is pressed by the developing unit 51 at the mounting position, no bending moment is generated in the LED head 57. Further, even when the LED head 57 is separated from the mounting position, no bending moment is generated in the LED head 57. Therefore, the durability of the LED head 57 can be increased and the image quality of the image forming apparatus can be maintained without particularly increasing the rigidity of the LED head 57.

Embodiment 2.
FIG. 8 is an external perspective view of the LED unit 239 of the second embodiment viewed from diagonally above with the arrow A direction shown in FIG. 1 as a common direction. For convenience, the LED head 57 is the photosensitive member shown in FIG. It shows the state when the body drum 52 is separated from the mounting position. The image forming apparatus 1 shown in FIG. 1 shows the image forming apparatus of the first embodiment, but in the present embodiment, the LED head holder 40 shown in FIG. 1 replaces the LED head holder 240. However, since the configuration diagram of the main part may have the same shape, FIG. 1 may be cited as the image forming apparatus of the present embodiment.

9 is a front view of the LED unit 239 shown in FIG. 8 as viewed from the direction of arrow A, and FIG. 10 is an arrow showing a cross section of the LED unit 239 shown in FIG. 9 including the front side urging protrusion 105 and the rear side urging protrusion 106. It is a cross-sectional view seen from the C direction, and FIG. 11 shows a right end portion of the LED unit 239 in a mounted state in which the LED head 57 is mounted at the mounting position of the developing unit 51 (FIG. 1) and corresponds to the printing operation. It is a partially enlarged view of the vicinity.

The main difference between the image forming apparatus of the second embodiment including the LED unit 239 and the image forming apparatus of the first embodiment including the LED unit 39 shown in FIG. 2 is that the link arm 42 in the LED unit 39 (FIG. The point is that a slide member 242 (FIG. 8) is provided instead of 2). Therefore, the parts of the image forming apparatus of the present embodiment that are common to the image forming apparatus 1 of the above-described first embodiment are designated by the same reference numerals, or the drawings are omitted and the description is omitted, and different points are emphasized. To explain.

In the vicinity of the right end portion of the LED unit 239, the LED head holder 240 main body holds the right slide member 242R holding the right end portion of the LED head 57, and the right slide member 242R is urged by the right coil spring 43R. Moreover, the LED head holding mechanism for which the movement is restricted is provided, and this LED head holding mechanism is the same in the vicinity of the left end portion of the LED unit 239, that is, both arms are rotated in the longitudinal direction of the LED head holder 240 as the head holding portion. It is formed plane-symmetrically with respect to the virtual center plane that intersects the arrow C direction at the center between the moving axes 41L and 41R.

Therefore, here, the configuration of the LED head holding mechanism on the right side is mainly described, and at the end of the code of the members arranged symmetrically, the numbers are the same, for example, the left slide member 242L and the right slide member 242R. L) and (R) are added to distinguish left and right, and the description of the LED head holding mechanism on the left side is omitted, and when it is not particularly necessary to distinguish left and right, these trailing signs may be omitted.

As shown in FIGS. 8 to 10, the right slide member 242R as a displacement member is surrounded by the front regulation surface 121R, the rear regulation surface 122R, the inner guide wall 251R, and the outer guide wall 252R (FIG. 9), and is front and rear. By fitting the front regulation protrusion 103R and the rear regulation protrusion 104R protruding into the front regulation guide elongated hole 125R and the rear regulation guide elongated hole 126R, respectively, the LED head holder 240 body slides perpendicularly to the reference plane. It has a configuration in which a flat plate portion that is possibly held and a right head engaging portion 102R that hangs down from a lower surface thereof are integrally formed.

As shown in the cross-sectional view of FIG. 10, the right coil spring 43R is arranged in a compressed state between the LED head holder 240 main body and the right slide member 242R, and urges the right slide member 242R. The right coil spring 43R is positioned and held by fitting the holding protrusion 127R formed on the LED head holder 240 into one end thereof, and the other end is pressed against the upper plane of the flat plate portion of the right slide member 242R. Have been placed.

The right slide member 242R is urged downward by the right coil spring 43R, but the front regulation protrusion 103R (rear regulation protrusion 104R) fitted in the front regulation guide elongated hole 125R (rear regulation guide elongated hole 126R). Is in contact with the lower end of the front regulation guide slot 125R (rear regulation guide slot 126R), and further downward movement is restricted. The configuration of the right head engaging portion 102R and the engaging relationship between the right head engaging portion 102R and the LED head 57 are as described in the first embodiment, and thus the description thereof will be omitted here.

In the above configuration, as the upper cover 35 (FIG. 1) rotates, the LED head 57 is placed in the mounting position and printed from a separated state separated from the mounting position of the developing unit 51 (FIG. 1). The operation of the LED head holding mechanism of the LED unit 239 when the LED unit 239 is displaced to the mounted state corresponding to the operating state will be described with reference to FIGS. 8 to 11.

8 and 9 show the state of the LED unit 239 when it is in the separated state. At this time, the slide member 242 is urged by the coil spring 43, and the front regulation protrusion 103 (rear regulation projection 104) is urged by the front regulation guide elongated hole 125 (rear side) of the front regulation surface 121 (rear regulation surface 122). It is in contact with the lower end of the regulation guide elongated hole 126), and further downward movement is restricted. The front urging projection 105 (rear urging projection 106) that fits into the front engaging elongated hole 151 (rear engaging elongated hole 152) of the LED head 57 is the front engaging elongated hole 151 (rear engaging elongated hole). The LED head 57 is held by the LED head holder 240 by abutting on the upper side portion of 152).

Therefore, since no load is applied to the LED head 57 in the longitudinal direction in this separated state, a bending moment is not generated by the urging force of the coil spring 43.

From this state, when the LED head 57 approaches the mounting surface 51a of the developing unit 51 (FIG. 1) as the upper cover 35 rotates, the contact projection 153 first moves on the mounting surface 51a of the developing unit 51. The space between the mounting surface 51a (FIG. 11) of the developing unit 51 and the LED head 57 is determined by abutting on the spacer 161 (FIG. 11) formed at the corresponding position, and at the same time, front, rear, left and right by a positioning means (not shown). The position of is also determined.

Further, when the upper cover 35 is rotated in the closing direction, only the LED head holder 240 moves further downward without the LED head 57 being displaced. Therefore, the slide member 242 is relative to the LED head holder 240 main body. As shown in FIG. 11, the front side regulation protrusion 103 (rear side regulation protrusion 104) is separated from the lower end portion of the front side regulation guide elongated hole 125 (regulation guide elongated hole 126), and the upper This separated state is maintained when the cover 35 is closed.

At this time, as shown in FIG. 11, the front urging protrusion 105 (rear urging protrusion 106) is located at the center of the front engaging elongated hole 151 (rear engaging elongated hole 152) in the longitudinal direction. Upon receiving the urging force of the coil spring 43, the lower edge portion 155 (156) formed parallel to the reference plane is pressed in the downward direction perpendicular to the reference plane.

Therefore, the LED head 57 is in a state where the contact projection 153 is in pressure contact with the spacer 161 of the developing unit 51 at a position at a predetermined distance from the mounting surface 51a of the developing unit 51, and is placed at the mounting position of the developing unit 51. It will be placed in a stable state.

At this time, the position (engagement location) where the front side urging protrusion 105 (rear side urging protrusion 106) abuts (engages) with the lower edge portion 155 (156) and presses the contact protrusion 153. Assuming that the center position of the pressure contact portion (pressure contact location) that is in pressure contact with the spacer 161 of the development unit 51 is perpendicular to the arrow C direction (the axial direction of the rotation axis 65 of the photoconductor drum 52), the same virtual plane is assumed. The pressing direction of the pressing force F, which is located on P and the anterior urging projection 105 (rear urging projection 106) presses the lower edge portion 155 (156), is parallel to this virtual plane P. There is.

Therefore, when the LED head 57 is in a mounting state corresponding to the printing operation and is urged by the coil spring 43 to the developing unit 51, the pressing force F is applied to the developing unit 51 without deriving a component force. Can be transmitted to the spacer 161 of.

As described above, according to the image forming apparatus of the present embodiment, when the LED head 57 is urged by the developing unit 51 at the mounting position, no bending moment is generated in the LED head 57. Further, even when the LED head 57 is separated from the mounting position, no bending moment is generated in the LED head 57. Therefore, the durability of the LED head 57 can be increased and the image quality of the image forming apparatus can be maintained without particularly increasing the rigidity of the LED head 57.

Further, in the description of the scope of claims and the embodiment described above, the terms "top", "bottom", "left", "right", "front", and "rear" are used, but these are for convenience. However, it does not limit the absolute positional relationship in the state where the image forming apparatus is arranged.

In the above-described embodiment, the present invention has been described by taking a color electrophotographic printer as an example, but the present invention is not limited to this, and an image is formed on a recording material by using an electrophotographic method. It can also be used for image forming devices such as copiers, facsimiles, and MFPs. Moreover, although the color printer has been described, it may be a monochrome printer.

1 image forming device, 10 paper feed cassette, 20 paper feeding section, 21 pickup roller, 22 paper feeding roller, 23 separation roller, 1 image forming device, 31 resist roller, 32 transfer roller, 33 pressure roller, 34 pressure roller, 35 Upper cover, 39 LED unit, 40 LED head holder, 41 arm rotation shaft, 42 link arm, 43 coil spring, 45 mechanism housing, 51 developing unit, 51a mounting surface, 52 photoconductor drum, 53 charging roller, 54 Developing roller, 55 Toner supply roller, 56 Cleaning blade, 57 LED head, 60 Transfer section, 61 Transfer belt, 62 Drive roller, 63 Tension roller, 65 Rotating shaft, 67 Transfer roller, 70 Fixing unit, 71 Heating roller, 72 Addition Pressure roller, 81 discharge roller pair, 82 discharge roller pair, 83 discharge tray, 90 path switching lever, 91 transfer roller, 92 double-sided transfer unit, 93 reversing roller, 94 transfer roller, 95 transfer roller, 96 transfer roller, 97 reversal pull-in Path, 101 arm part, 102 head engaging part, 103 front side regulation protrusion, 104 rear side regulation protrusion, 105 front side urging protrusion, 106 rear side urging protrusion, 107 upper plane part, 121 front side regulation surface, 122 rear side regulation Surface, 125 Front regulation guide slot, 126 Rear regulation guide slot, 127 Holding protrusion, 151 Front engagement slot, 152 Rear engagement slot, 153 Contact protrusion, 155 Lower edge, 156 Lower Edge, 161 spacer, 239 LED unit, 240 LED head holder, 242 slide member, 251 inner guide wall, 252 outer guide wall.

Claims (10)

An exposure head part with a contact part and
A head holding portion that holds the exposure head portion and
A holding member that holds the head holding portion and
It has an image forming unit including an image carrier and a mounting portion on which the exposure head portion is mounted by abutting the contact portion.
The head holding portion is
A displacement member that is displaceably held with respect to the main body of the head holding portion and engages with the exposure head portion to hold the exposure head portion.
An urging member that urges the displacement member in one direction and
It is provided with a regulating unit that regulates the movement of the displacement member in the one direction beyond a predetermined position.
When the exposure head portion is placed on the above-described mounting portion and the holding member moves,
An image forming apparatus, characterized in that the displacement member is separated from the predetermined position against the bias. The holding member is an opening / closing lid, and when the exposure head portion is placed on the above-mentioned mounting portion and the opening / closing lid is closed, the displacement member is separated from the predetermined position against the bias. The contact portion is in a state of being in pressure contact with the above-mentioned placement portion
Claim 1 is characterized in that the engagement portion between the exposure head portion and the displacement member and the pressure contact portion are located on the same plane of a virtual plane perpendicular to the rotation axis direction of the image carrier. The image forming apparatus according to the description. The image forming apparatus according to claim 2, wherein the pressing direction of the pressing force generated at the engaging portion is configured to be parallel to the virtual plane. The image forming apparatus according to any one of claims 1 to 3, wherein the displacement member has an engaging portion provided with a protrusion that fits into the fitting hole formed in the exposure head portion. The holding member is an opening / closing lid, the protrusion is cylindrical, and when the opening / closing lid is closed, the fitting hole is provided with an edge portion parallel to the rotation axis of the image carrier, and the protrusion is provided. 4. The image forming apparatus according to claim 4, wherein the image is in contact with the edge portion. The image forming apparatus according to claim 4 or 5, wherein the engaging portion is formed so that the protruding portion can be freely inserted into and released from the fitting hole by deformation. The image forming apparatus according to any one of claims 1 to 6, wherein the displacement member is a link arm rotatably held by the head holding portion main body. The image forming apparatus according to any one of claims 1 to 6, wherein the displacement member is a slide member that is slidably held by the head holding portion main body. The image forming apparatus according to any one of claims 1 to 8, wherein the urging member is a coil spring that is hung between the head holding portion main body and the displacement member in a compressed state. .. The image forming apparatus according to claim 7, wherein the urging member is a torsion spring hung between the head holding portion main body and the link arm.

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