JP4645691B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that exposes a photosensitive member such as a photosensitive drum with an exposure member having a plurality of blinking portions such as an LED head.

  2. Description of the Related Art Conventionally, as an image forming apparatus that exposes a photosensitive drum with an LED head, an image forming apparatus in which a spacer is provided between the LED head and the photosensitive drum to maintain a distance in the optical axis direction between the LED head and the photosensitive drum. (See Patent Document 1). Specifically, in this technique, the spacer is provided integrally with the LED head.

JP 2002-361931 A

  In the prior art, since the spacer is provided integrally with the LED head, the spacer that is in sliding contact with the rotating photosensitive drum is pulled in the rotating direction of the photosensitive drum by friction with the photosensitive drum, and the LED head rotates in the rotating direction. May move to. On the other hand, a method of regulating the position in the rotation direction by providing a positioning member on the downstream side of the rotation direction of the LED head is conceivable. However, when the spacer is pulled in the rotation direction of the photosensitive drum, the LED head is centered on the positioning member. As can be tilted. When the LED head is tilted in this way, the focal position of the light emitted from the LED head is shifted, which causes a problem that the image quality is deteriorated.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of improving image quality by suppressing inclination of an LED head (exposure member).

The present invention for solving the above problems includes a photosensitive member rotatably supported by an apparatus main body, an exposure member for exposing the photosensitive member, means for pressing the exposure member toward the photosensitive member, and the exposure member. An image forming apparatus provided with an interval holding member that is in contact with the photoconductor and holds an interval between the exposure member and the photoconductor, the rotation direction of the photoconductor relative to the exposure member The exposure member is disposed on the downstream side, abuts against the exposure member, restricts movement of the exposure member in the rotation direction of the photosensitive member by being pulled by the photosensitive member , and the exposure member in the rotation direction is controlled . A positioning member that determines a position, and contacts the exposure member at a position upstream of the exposure member in the rotation direction and at a position farther from the photoconductor than a contact position between the positioning member and the exposure member; The exposure Material is characterized in that, the swing restriction member that restricts the swings around the said positioning member provided in the apparatus main body.

  According to the present invention, the interval holding member that contacts the rotating photosensitive member is pulled in the rotation direction of the photosensitive member by friction with the photosensitive member, so that the exposure member can be exposed even if the exposure member tries to swing around the positioning member. Since the swing of the member is suppressed by the swing restricting member, the tilt of the exposure member can be suppressed. Thereby, since it is suppressed that the focus position of the light irradiated from an exposure member shifts | deviates, image quality can be improved.

  According to the present invention, even if the exposure member tries to swing around the positioning member, the swing (inclination) of the exposure member can be suppressed by the swing restriction member, so that the image quality can be improved.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing an overall configuration of a color printer as an example of an image forming apparatus. In the following description, the overall configuration of the color printer will be described first, and then the details of the features of the present invention will be described.

  In the following description, the direction will be described with reference to the user when using the color printer. That is, in FIG. 1, the right side toward the paper surface is “front side (front side)”, the left side toward the paper surface is “rear side (back side)”, the back side toward the paper surface is “right side”, and the paper surface is facing. Let the near side be the “left side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, a color printer 1 includes a paper feeding unit 20 that supplies paper P and an image forming unit that forms an image on the fed paper P in a main body housing 10 as an example of an apparatus main body. 30 and a paper discharge unit 90 for discharging the paper P on which an image is formed.

  An upper cover 12 that can be opened and closed relative to the main body housing 10 is provided on the upper portion of the main body housing 10 so as to be rotatable up and down around a hinge 12A provided on the rear side. An upper surface of the upper cover 12 serves as a paper discharge tray 13 for accumulating the paper P discharged from the main body housing 10, and a plurality of LED mounting members 14 for holding LED units 40 described later are provided on the lower surface. Yes.

  The paper feeding unit 20 is provided in the lower part of the main body housing 10, and is a paper feeding tray 21 that is detachably attached to the main body housing 10, and a paper that conveys the paper P from the paper feeding tray 21 to the image forming unit 30. A supply mechanism 22 is mainly provided. In the paper feed unit 20 configured as described above, the paper P in the paper feed tray 21 is separated one by one by the paper supply mechanism 22 and supplied to the image forming unit 30.

  The image forming unit 30 mainly includes four LED units 40 as an example of an exposure member, four process cartridges 50, a transfer unit 70, and a fixing unit 80.

  The LED unit 40 is supported by the LED mounting member 14 and is appropriately positioned by a positioning member 100 and a swing regulating member 110 provided in the main body housing 10. The detailed structures of the LED unit 40, the positioning member 100, and the swing restricting member 110 will be described later.

  The process cartridge 50 is arranged side by side in the front-rear direction between the upper cover 12 and the paper feeding unit 20 and is a photosensitive drum 53 as an example of a photosensitive member that is rotatably supported by the main body housing 10. It is configured to include a charger, a well-known developing roller with a reference numeral omitted, and a toner storage chamber.

  The transfer unit 70 is provided between the paper feeding unit 20 and each process cartridge 50 and mainly includes a drive roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74.

  The driving roller 71 and the driven roller 72 are arranged in parallel in a spaced manner in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyance belt 73 is in contact with each photosensitive drum 53. In addition, four transfer rollers 74 that sandwich the conveyor belt 73 between the photosensitive drums 53 are arranged inside the conveyor belt 73 so as to face the photosensitive drums 53. A transfer bias is applied to the transfer roller 74 by constant current control during transfer.

  The fixing unit 80 is disposed on the back side of each process cartridge 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81.

  In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 53 is uniformly charged by a charger and then exposed by each LED unit 40. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 53. Thereafter, toner is supplied to the electrostatic latent image from the developing roller, so that the toner image is carried on the photosensitive drum 53.

  Next, the paper P supplied onto the conveyor belt 73 passes between each photosensitive drum 53 and each transfer roller 74 disposed inside the conveyor belt 73, thereby forming the sheet P on each photosensitive drum 53. The toner image is transferred onto the paper P. Then, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

  The paper discharge unit 90 mainly includes a plurality of pairs of transport rollers 91 that transport the paper P. The sheet P on which the toner image has been transferred and heat-fixed is transported by the transport roller 91, discharged to the outside of the main body housing 10, and accumulated in the paper discharge tray 13.

<Configuration of LED unit, positioning member and swing regulating member>
Next, the structure of the LED unit 40, the positioning member 100, and the rocking | fluctuation control member 110 which are the characterizing parts of this invention is demonstrated in detail.

[Configuration of LED unit]
First, the configuration of the LED unit 40 will be described. 2 is a front view showing the configuration of the LED unit, and FIG. 3 is an exploded perspective view (a) showing the left eccentric cam and an exploded perspective view (b) showing the right eccentric cam. .

  As shown in FIG. 2, the LED unit 40 includes an LED head 41, two wire springs (elastic members) 42, a support frame 43, two guide rollers 44 as an example of a spacing member, An eccentric cam (adjusting member) 45, 46 is mainly provided.

  The LED head 41 includes a plurality of LEDs 41A, a head frame 41B, and a lens array 41C. In the present embodiment, the blinking part is configured by a lens array 41C and a plurality of LEDs 41A as an example.

  The plurality of LEDs 41 </ b> A are arranged in a line in accordance with a predetermined pixel pitch in the left-right direction (the axial direction of the photosensitive drum 53), and are appropriately driven to emit light and direct light toward the photosensitive drum 53. It is comprised so that it may irradiate. Specifically, each LED 41 </ b> A receives a signal from a control device (not shown) based on image data to be formed, emits light, and exposes the photosensitive drum 53.

  The head frame 41B is made of resin, and supports a plurality of LEDs 41A at the lower part thereof. The head frame 41B is made of resin, so that the LED head 41 can be reduced in size and cost, and discharge from high-voltage components such as a charger is suppressed.

  The lens array 41C is composed of a plurality of Selfoc lenses (registered trademark) arranged in correspondence with the LEDs 41A, extends along the arrangement direction of the LEDs 41A, and leaves a little on both ends of the lower surface of the head frame 41B. It is fixed to the head frame 41B.

  The wire spring 42 is a linear tension spring formed in a substantially V shape, and urges the LED head 41 toward the support frame 43. Specifically, the wire spring 42 has a V-shaped main body portion 42A, an action portion 42B formed at the lower end of the main body portion 42A, and an engaging claw portion 42C formed at the upper end of the main body portion 42A. ing.

  The main body 42A is bent and formed in a V shape so as to expose operation portions (cross grooves 45C and 46C described later; see FIG. 3) of eccentric cams 45 and 46 described later.

  The action part 42B is a part that applies a pressing force to the LED head 41, and is in contact with a part of the lower surface of the head frame 41B that is on the outer side in the left-right direction from the plurality of LEDs 41A (lens array 41C). Further, the action part 42B is formed in a V shape by being bent upward and then bent downward, whereby the contact portion between the action part 42B and the head frame 41B becomes substantially dotted. Yes.

  The engaging claw portion 42C is formed in a V shape so as to be hooked on the upper surface of an engaging pin portion 43C of the support frame 43 described later.

  The support frame 43 supports the LED head 41 via the wire spring 42, and includes a base portion 43A extending in the left-right direction and a pair of extending portions 43B extending downward from both ends of the base portion 43A. Configured.

  In the base portion 43A, two engaging pin portions 43C that support the wire spring 42 and two bearing portions 43D and 43E that rotatably support the eccentric cams 45 and 46 are formed at symmetrical positions. On the upper surface of the base portion 43A, two pressing springs (elastic members) 47 for pressing the support frame 43 toward the lower photosensitive drum 53 are disposed at left and right symmetrical positions. The frame 43 is pressed by the two pressing springs 47 with a good balance in the left-right direction.

  The extending portion 43B is formed with a length protruding downward from the lower surface of the LED head 41 supported by the base portion 43A via the wire spring 42, and a guide roller 44 can be rotated at the lower end portion thereof. A shaft portion 43F is provided for support.

  The guide roller 44 is a cylindrical member, and is installed at a predetermined distance from the LED head 41 by being rotatably provided on the shaft portion 43F at the lower end portion of the extending portion 43B of the support frame 43. Yes. The guide roller 44 is pressed against the photosensitive drum 53 by the urging force from the aforementioned pressing spring 47 being transmitted through the support frame 43, and is driven to rotate by the photosensitive drum 53. The guide roller 44 comes into contact with the photosensitive drum 53 so that the distance (operating distance S) in the optical axis direction between the photosensitive drum 53 and the LED head 41 supported by the support frame 43 is maintained. ing.

  The guide roller 44 may be in contact with a photosensitive layer (exposed layer) on the surface of the photosensitive drum 53, or may be in contact with a region outside the photosensitive layer in the left-right direction (region without the photosensitive layer). May be.

  The eccentric cams 45 and 46 are disposed between the LED head 41 and the base portion 43A of the support frame 43, and are configured to press the LED head 41 in the optical axis direction while receiving the urging force of the wire spring 42. Has been. Specifically, the eccentric cams 45 and 46 are disposed at positions on the upper surface of the head frame 41B that are in contact with a portion on the outer side in the left-right direction with respect to the plurality of LEDs 41A (lens array 41C), and the urging force of the wire spring 42 is set. It arrange | positions so that it may overlap with the action part 42B of the wire spring 42 seeing from a direction (up-down direction).

  The left eccentric cam 45 of the pair of eccentric cams 45, 46 is configured to press the LED head 41 at two locations as shown in FIG. 3A, and the right eccentric cam 46 is As shown to 3 (b), it is comprised so that the LED head 41 may be pressed in one place. That is, there are only three contact portions between all the eccentric cams 45 and 46 and the LED head 41.

  Specifically, as shown in FIG. 3A, the left eccentric cam 45 includes two cylindrical portions 45A arranged concentrically, and each cylindrical portion 45A at a position eccentric from the center of each cylindrical portion 45A. It has one shaft part 45B to be connected.

  The shaft portion 45B of the eccentric cam 45 is rotatably supported by the bearing portion 43D with a predetermined astringency (difficulty of movement) by being fitted to the C-shaped bearing portion 43D of the support frame 43. . Here, the astringency between the shaft portion 45 </ b> B and the bearing portion 43 </ b> D is set such that the eccentric cam 45 does not rotate with the urging force of the wire spring 42.

  Further, a cross groove 45C whose center coincides with the center of the shaft portion 45B is formed on the end surface of the cylindrical portion 45A of the eccentric cam 45. Then, by engaging a plus driver in the cross groove 45C and rotating the plus driver by a predetermined amount with a force larger than the urging force of the wire spring 42, the eccentric cam 45 rotates by a predetermined amount with respect to the support frame 43, It will be maintained in that position.

  As shown in FIG. 3B, the right eccentric cam 46 is formed in a shape obtained by removing one cylindrical portion 45A from the left eccentric cam 45. That is, the right eccentric cam 46 includes a cylindrical portion 46A, a shaft portion 46B, and a cross groove 46C that have the same configuration as the left eccentric cam 45. Then, the shaft portion 46B of the eccentric cam 46 is rotatably supported by the bearing portion 43E with the same astringency as described above by being fitted to the substantially cylindrical bearing portion 43E of the support frame 43.

  In the LED unit 40 configured as described above, the support roller 43 is positioned at a predetermined position with respect to the photosensitive drum 53 by the guide roller 44 coming into contact with the photosensitive drum 53 as shown in FIG. become. Further, the LED head 41 is pressed against the eccentric cams 45 and 46 supported by the support frame 43 positioned as described above, whereby the LED head 41 is positioned relative to the photosensitive drum 53.

  Then, by appropriately operating the eccentric cams 45 and 46 in this state, the LED head 41 moves back and forth with respect to the support frame 43, and the working distance S is finely adjusted. Since the working distance S varies greatly due to the influence of manufacturing errors of the guide roller 44, the support frame 43, the eccentric cams 45 and 46, and the LED head 41, the working distance S is desired for the adjustment width of the eccentric cams 45 and 46. May not be possible. In this case, a coarse adjustment plate for coarse adjustment of the working distance S may be appropriately provided between the eccentric cams 45 and 46 and the LED head 41.

  The adjustment of the working distance S is performed when the LED unit 40 is manufactured, and is not performed after the LED unit 40 is assembled to the main body housing 10. Therefore, after adjusting the working distance S, the LED head 41 may be fixed to the support frame 43 by a fixing means such as a binding band or an adhesive that does not elastically deform, and then the wire spring 42 may be removed.

[Configuration of positioning member and swing regulating member]
Next, the structure of the positioning member 100 and the rocking | fluctuation control member 110 is demonstrated. In the drawings to be referred to, FIG. 4 is a view showing a positioning member and a swing restricting member, a side view (a) showing a state in which the guide roller of the LED unit is in contact with the photosensitive drum, and the guide roller of the LED unit. It is a side view (b) which shows the state spaced apart from the photosensitive drum.

  As shown in FIG. 4A, the positioning member 100 is a cylindrical pin, and is disposed in front of the LED unit 40 (downstream in the rotation direction of the photosensitive drum 53). Specifically, the positioning member 100 is disposed so as to face the front surface of the extending portion 43 </ b> B of the support frame 43 constituting the LED unit 40.

  Then, the positioning member 100 positions the LED unit 40 in the front-rear direction (the rotation direction of the photosensitive drum 53) by contacting the front surface of the extending portion 43B of the support frame 43 on the photosensitive drum 53 side. .

  The swing restricting member 110 is a cylindrical pin and is disposed behind the LED unit 40 (upstream in the rotational direction of the photosensitive drum 53). Specifically, the swing restricting member 110 is positioned above the position where the positioning member 100 is in contact with the extending portion 43B of the support frame 43 (in the direction away from the photosensitive drum 53), so that the LED unit 40 is positioned. The swinging around the member 100 is restricted.

  In addition, a first coil spring 120 as an example of a first pressing member is provided on the opposite side of the LED unit 40 from the positioning member 100, and on the opposite side of the LED unit 40 from the swing restricting member 110, A second coil spring 130 as an example of a two-pressing member is provided.

  The first coil spring 120 is a spring that is fixed to the main body housing 10 and presses the LED unit 40 (support frame 43) toward the positioning member 100, and a contact member 140 that contacts the LED unit 40 at the front end thereof. Is provided. The first coil spring 120 is disposed at the same position as the positioning member 100 in the vertical direction (optical axis direction). Specifically, the portion where the contact member 140 contacts the LED unit 40 (the portion where the urging force of the first coil spring 120 acts on the LED unit 40) is the portion where the positioning member 100 contacts the LED unit 40 in the vertical direction. It is arranged at the same position.

  In addition, an inclined surface 141 that is inclined toward the photosensitive drum 53 toward the LED unit 40 from the first coil spring 120 is formed on the upper portion of the contact member 140. As a result, as shown in FIG. 4B, when the LED unit 40 is inserted toward the photosensitive drum 53, the LED unit 40 comes into contact with the inclined surface 141 and the contact member 140 moves backward. Thus, the first coil spring 120 is contracted in the front-rear direction.

  The second coil spring 130 is a spring that is fixed to the LED unit 40 (support frame 43) and presses the LED unit 40 toward the swing restricting member 110, and the front end thereof is in contact with the main body housing 10. A member 150 is provided. The second coil spring 130 is disposed at the same position as the swing restricting member 110 in the vertical direction (optical axis direction). Specifically, a portion where the second coil spring 130 is fixed to the LED unit 40 (an action portion in which the urging force of the second coil spring 130 acts on the LED unit 40) is configured such that the swing restriction member 110 and the LED unit 40 are in the vertical direction. It is arranged at the same position as the abutting part.

  Further, an inclined surface 151 that is inclined toward the photosensitive drum 53 toward the second coil spring 130 from the main body housing 10 is formed below the contact member 150. As a result, as shown in FIG. 4B, when the LED unit 40 is inserted toward the photosensitive drum 53, the inclined surface 151 contacts the main body housing 10 and the contact member 150 moves rearward. Thus, the second coil spring 130 is contracted in the left-right direction.

[Operation of positioning member and swing regulating member]
Next, the operation of the positioning member 100 and the swing restriction member 110 will be described.
As shown in FIG. 4A, when the photosensitive drum 53 rotates, the guide roller 44 that contacts the photosensitive drum 53 is pulled in the rotational direction of the photosensitive drum 53 by friction with the photosensitive drum 53, whereby the LED unit 40 is Although it tries to move in the rotation direction, this movement is restricted by the positioning member 100.

  Further, the LED unit 40 regulated by the positioning member 100 tries to swing around the positioning member 100 when the guide roller 44 is pulled in the rotation direction of the photosensitive drum 53. It is suppressed by the restriction member 110. Therefore, the LED unit 40 is held at the initial position by the positioning member 100 and the swing restriction member 110.

According to the above, the following effects can be obtained in the present embodiment.
Even if the guide roller 44 is pulled in the rotation direction of the photosensitive drum 53 and the LED unit 40 tries to swing around the positioning member 100, the swing (tilt) of the LED unit 40 is suppressed by the swing restricting member 110. The focus position of the light emitted from the LED unit 40 is prevented from shifting, and the image quality can be improved.

  Since the action part of the first coil spring 120 (the part where the contact member 140 contacts the LED unit 40) and the contact part of the positioning member 100 with the LED unit 40 are arranged at the same position in the vertical direction, the LED unit 40 Can be reliably positioned by being brought into close contact with the positioning member 100.

  Since the action part of the second coil spring 130 (the part where the second coil spring 130 is fixed to the LED unit 40) and the contact part of the swing regulating member 110 with the LED unit 40 are arranged at the same position in the vertical direction, The LED unit 40 can be brought into close contact with the swing restricting member 110 to reliably suppress the swing of the LED unit 40.

  By fixing the first coil spring 120 to the main body housing 10, the front-rear width of the lower portion of the LED unit 40 can be reduced, so that a narrow gap between the positioning member 100 and the swinging restriction member 110 is formed. The LED unit 40 can be satisfactorily passed. Further, since the second coil spring 130 is fixed to the LED unit 40, the LED unit 40 is placed in a wider gap between the swing restricting member 110 and the main body housing 10 as compared to the case where the second coil spring 130 is fixed to the main body housing 10. It can pass well.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the said embodiment, although the 1st coil spring 120 and the positioning member 100 were arrange | positioned in the same position in the up-down direction, this invention is not limited to this. For example, as shown in FIG. 5, the first coil spring 120 may be disposed at a position below the positioning member 100 (on the photosensitive drum 53 side). Specifically, the action portion of the first coil spring 120 (the portion where the contact member 140 contacts the LED unit 40) is positioned below (the photosensitive drum 53 side) the contact portion of the positioning member 100 with the LED unit 40. You may arrange.

  According to this, a moment is applied to the LED unit 40 by the urging force of the first coil spring 120, and the LED unit 40 can be reliably pressed against the positioning member 100 and the swing regulating member 110. It can be done reliably. In addition, since the LED unit 40 can be pressed against the positioning member 100 and the swing restricting member 110 with only one first coil spring 120, the second coil spring 130 is not necessary, and the cost can be reduced.

  In the said embodiment, although the 2nd coil spring 130 and the rocking | fluctuation control member 110 were arrange | positioned in the same position in the up-down direction, this invention is not limited to this. For example, as shown in FIG. 6, the second coil spring 130 may be disposed at a position above the swinging restriction member 110 (in a direction away from the photosensitive drum 53). Specifically, the action portion of the second coil spring 130 (the portion where the second coil spring 130 is fixed to the LED unit 40) is disposed at a position above the contact portion of the swing regulating member 110 with the LED unit 40. Also good.

  According to this, a moment is applied to the LED unit 40 by the urging force of the second coil spring 130, and the LED unit 40 can be reliably pressed against the positioning member 100 and the swing regulating member 110. It can be done reliably. Further, since the LED unit 40 can be pressed against the positioning member 100 and the swing restricting member 110 with only one second coil spring 130, the first coil spring 120 is not necessary, and the cost can be reduced.

  In the above embodiment, the coil springs 120 and 130 are employed as the pressing member. However, the present invention is not limited to this, and for example, an elastic member such as a torsion spring or a leaf spring is employed, or the iron core is driven by an air cylinder or electromagnetic force. You may employ | adopt things other than elastic members, such as a solenoid to make.

  Moreover, it is good also as a structure which arrange | positions the LED unit 40 between the positioning member 100 and the rocking | fluctuation control member 110, without providing a pressing member. Even in this case, the LED unit 40 is pressed against the positioning member 100 and the swing restricting member 110 by using the force with which the lower end of the LED unit 40 is pulled forward by friction with the photosensitive drum 53, and positioning is performed. It can be carried out.

  In the above embodiment, the positioning member 100 and the swing restriction member 110 are formed in a columnar shape, but the present invention is not limited to this, and may be formed in a prismatic shape, for example.

  In the embodiment, the LED unit 40 having the LED head 41 and the support frame 43 is mainly used as the exposure member. However, the present invention is not limited to this, and the LED head 41 may be used as the exposure member. That is, the LED roller 41 may be rotatably provided with a guide roller 44 as a spacing member, and the positioning member 100 and the swing restricting member 110 may be disposed so as to sandwich the LED head 41.

  In the above-described embodiment, the rotatable guide roller 44 is used as the spacing member. However, the present invention is not limited to this, and a non-rotating member such as a spacer having a concave curved surface that is in surface contact with the outer peripheral surface of the photosensitive drum. May be employed as a spacing member. By providing the interval holding member, the working distance can be held even if the photosensitive drum is eccentric.

  In the above-described embodiment, the LED head 41 including the plurality of LEDs 41A arranged in a line in the left-right direction is adopted as one component of the exposure member, but the present invention is not limited to this. For example, you may employ | adopt the LED head which has several row | line | column before and after several LED arranged in the left-right direction. In addition, a plurality of blinking parts are configured by one light emitting element such as an LED or a fluorescent lamp and a plurality of liquid crystal or PLZT element optical shutters arranged in the left-right direction outside the light emitting element. You may employ | adopt what has. Further, the light source is not limited to the LED, but may be an EL (electroluminescence) element or a phosphor.

In the above embodiment, the present invention is applied to the color printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine.
In the above-described embodiment, the photosensitive drum 53 is employed as the photosensitive member. However, the present invention is not limited to this, and for example, a belt-shaped photosensitive member may be employed.

1 is a cross-sectional view illustrating an overall configuration of a color printer as an example of an image forming apparatus. It is a front view which shows the structure of an LED unit. They are an exploded perspective view (a) which shows a left eccentric cam, and an exploded perspective view (b) which shows a right eccentric cam. It is a figure which shows a positioning member and a rocking | fluctuation control member, The side view (a) which shows the state which made the guide roller of LED unit contact the photosensitive drum, and the state which separated the guide roller of LED unit from the photosensitive drum It is a side view (b) shown. It is a side view which shows the form which presses an LED unit only with a 1st coil spring. It is a side view which shows the form which presses an LED unit only with a 2nd coil spring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 10 Main body housing | casing 40 LED unit 41 LED head 43 Support frame 44 Guide roller 53 Photosensitive drum 100 Positioning member 110 Swing control member 120 1st coil spring 130 2nd coil spring

Claims (4)

A photosensitive member rotatably supported by the apparatus body;
An exposure member for exposing the photoreceptor;
Means for pressing the exposure member toward the photoreceptor;
An image forming apparatus provided with an interval holding member that is provided on the exposure member and holds the interval between the exposure member and the photoconductor in contact with the photoconductor,
It is arranged downstream of the exposure member in the rotation direction of the photoconductor, abuts against the exposure member, and the exposure member is pulled by the photoconductor to restrict movement in the rotation direction of the photoconductor. A positioning member that determines a position of the exposure member in the rotation direction;
The exposure member is in contact with the exposure member at a position upstream of the exposure member in the rotation direction and at a position farther from the photoconductor than a contact position between the positioning member and the exposure member. An image forming apparatus comprising: a swing restricting member that restricts swinging about the center of the apparatus main body. A first pressing member that presses the exposure member toward the positioning member;
The first pressing member is arranged at the same position as the positioning member or at a position closer to the photoconductor than the positioning member in the optical axis direction of light emitted from the exposure member. The image forming apparatus according to 1. A second pressing member that presses the exposure member toward the swing restriction member;
The second pressing member is disposed at the same position as the swing restricting member or at a position farther from the photoconductor than the swing restricting member in the optical axis direction of the light emitted from the exposure member. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The first pressing member is attached to the apparatus main body,
The image forming apparatus according to claim 3, wherein the second pressing member is attached to the exposure member.

Images