JP5609964B2 - Exposure apparatus and image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus that performs exposure with an LED head having a plurality of LEDs (light emitting diodes).

In general, an image forming apparatus irradiates a charged photosensitive drum with light to form an electrostatic latent image on the photosensitive drum, and supplies a developer to the electrostatic latent image. By transferring to the recording sheet, a predetermined image is formed on the recording sheet. As such an image forming apparatus, conventionally, an LED head having a plurality of LEDs for irradiating light to a photosensitive drum, and an LE
A device including a pair of main body frames that support both end portions of the D head in the longitudinal direction (LED arrangement direction) is known (see Patent Document 1).

Japanese Patent Laid-Open No. 61-95956

In the prior art, however, it is necessary to position the LED head so as not to move in the longitudinal direction with respect to the main body frame so that the light irradiation position in the axial direction of the photosensitive drum does not shift.

SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can position an exposure member in a longitudinal direction with respect to a main body frame.

According to a first aspect of the present invention, there is provided a photosensitive drum and a plurality of light emitting portions, and the photosensitive drum is exposed so as to extend in a longitudinal direction along an axis of the photosensitive drum and to face the photosensitive drum. An exposure member, a first frame opposite to one end in the longitudinal direction of the exposure member, having a reference portion, a base end fixed to the first frame, and a tip engaged with one end of the exposure member And a leaf spring that presses one end of the exposure member against the reference portion.
2nd invention which solves the said subject has a plurality of light emitting parts, extends in the longitudinal direction, and faces an exposure member for exposing the photosensitive drum, and one end portion in the longitudinal direction of the exposure member, A first frame having a reference portion; a base end portion fixed to the first frame; and a distal end portion that engages with one end portion of the exposure member; and one end portion of the exposure member to the reference portion And a leaf spring that is pressed so as to be drawn.
According to a third aspect of the present invention for solving the above-mentioned problems, a plurality of light emitting elements are arranged in a first direction along the rotation axis direction of the rotating image carrier, and the image carrier is arranged. An exposure unit that exposes, an end holding unit that holds an end of the one end of the exposure unit, and an end of the exposure unit that is formed on the one end holding unit, A first reference portion serving as a reference for determining the position of the exposure means in the first direction; and holding the end of the exposure means on the other end side so that the exposure means can be moved in the first direction. The other end side holding portion, and an applying portion for applying a force for pressing the end portion on the one end side of the exposure means toward the first reference portion on the one end side of the exposure means, The exposure means receives a pressing force from the applying portion on the one end side. And a contact portion that contacts the first reference portion, and the contact portion is pressed against the first reference portion by a pressing force received by the receiving portion, and the first end portion is pressed on the other end side. It is characterized by not receiving force in the direction.
According to a fourth aspect of the present invention for solving the above-mentioned problems, a rotating image holding member, a charging device for charging the image holding member, one end and the other end are provided. A plurality of light emitting elements arranged in one direction, exposing the image carrier to form an electrostatic latent image on the image carrier, and one end holding the one end of the exposure unit A first reference that is formed on the side holding portion and the one end side holding portion and serves as a reference for determining the position of the exposure means in the first direction by contacting the end on the one end side of the exposure means. A second end side holding portion that holds the other end side end portion of the exposure means, and an end portion on the one end side of the exposure means that is movable in the first direction. Giving to apply a force pressing toward the first reference portion on the one end side of the exposure means And a developing device that develops the electrostatic latent image formed on the image holding member to form an image, wherein the exposure unit receives a pressing force from the applying portion on the one end side. And a contact portion that contacts the first reference portion, and the contact portion is pressed against the first reference portion by the pressing force received by the receiving portion, and the first end on the other end side. It is characterized by not receiving force in the direction of.

According to the second aspect of the first, it can be positioned EXPOSURE member in the longitudinal direction.

According to the first and second aspects of the invention, since the one end of the exposure member is pressed against the reference portion of the first frame by the leaf spring, the exposure member can be positioned in the longitudinal direction with respect to the first frame. .

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, FIG. 2 is an enlarged view of an LED unit and a process cartridge in FIG. a) is an exploded perspective view of the LED unit, (b) is an enlarged perspective view of the guide roller, FIG. 4 is a side view showing the positional relationship between the LED unit and the side plate, and FIG. It is the figure which looked at the photosensitive drum and LED unit from back.

Here, 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 left side toward the paper surface is “front side (front side)”, the right side toward the paper surface is “rear side (back side)”, the back side toward the paper surface is “left side”, and it faces the paper surface. Let the near side be the “right side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

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

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. The 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 attachments for holding an LED unit 40 as an example of an exposure member to be described later are mounted on the lower surface. A member 14 is provided.

A main body frame 15 is provided in the main body casing 10 as a part of an apparatus main body that detachably accommodates each process cartridge 50 described later. The main body frame 15 is provided with a pair of metal side frames 15A (only one side is shown) provided on the left and right sides and a cross member 15B connecting the pair of side frames 15A on the front and rear. The main body frame 15 is fixed to the main body housing 10 or the like. The side frame 15A is an arrangement direction of light emitting portions of the LED head 41 (to be described later) (referred to as a main direction, and in this embodiment, the photosensitive drum 53
It is the same as the axial direction. ), And is a member that directly or indirectly supports and positions the photosensitive drum 53.

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. The paper supply mechanism 22 is provided on the front side of the paper supply tray 21 and mainly includes a paper supply roller 23, a separation roller 24, and a separation pad 25.

In the paper feed unit 20 configured in this way, the paper P in the paper feed tray 21 is separated one by one and sent upward, and passes through between the paper dust removal roller 26 and the pinch roller 27 in the process. After the powder is removed, the direction is changed backward through the conveyance path 28 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 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 as shown in FIG. 2, the drum unit 51 and the developing unit 61 that is detachably attached to the drum unit 51. And. The process cartridge 50
The process cartridge 50 is supported by the side frame 15A and includes a photosensitive drum 5.
3 is supported. Each process cartridge 50 has the same configuration except that the color of the toner stored in the toner storage chamber 66 of the developing unit 61 is different.

The drum unit 51 mainly includes a drum frame 52, a photosensitive drum 53 as an example of a photosensitive member rotatably supported by the drum frame 52, and a scorotron charger 54.

The developing unit 61 includes a developing frame 62, a developing roller 63 and a supply roller 64 that are rotatably supported by the developing frame 62, and a layer thickness regulating blade 65. The developing unit 61 includes a toner storage chamber 66 that stores toner. Yes. The process cartridge 50 has an exposure hole 55 formed between the developing frame 62 and the drum frame 52 when the developing unit 61 is mounted on the drum unit 51. A drum 53 is disposed. Then, by inserting the LED unit 40 into the exposure hole 55, the LED
A unit 40 is disposed to face the photosensitive drum 53.

As shown in FIG. 1, the transfer unit 70 is provided between the paper feeding unit 20 and each process cartridge 50, and includes a driving roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 7.
4 is mainly provided.

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 the scorotron charger 54 and then irradiated from each LED unit 40.
It is exposed with ED light. 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.

In addition, the toner in the toner storage chamber 66 is supplied to the developing roller 63 by the rotation of the supply roller 64, and enters between the developing roller 63 and the layer thickness regulating blade 65 by the rotation of the developing roller 63 and has a constant thickness. It is carried on the developing roller 63 as a thin layer.

The toner carried on the developing roller 63 is supplied to the electrostatic latent image formed on the photosensitive drum 53 when the developing roller 63 comes into contact with the photosensitive drum 53. As a result, the toner is selectively carried on the photosensitive drum 53 to visualize the electrostatic latent image, and a toner image is formed by reversal development.

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 paper discharge side transport path 91 formed so as to extend upward from the outlet of the fixing unit 80 and to be reversed to the front side, and a plurality of pairs of transport rollers 92 that transport the paper P. I have. The paper P on which the toner image has been transferred and heat-fixed is transported through a paper discharge-side transport path 91 by a transport roller 92, discharged outside the main body housing 10, and accumulated in the paper discharge tray 13.

<Configuration of LED unit>
Next, the LED unit 40, which is a characteristic part of the present invention, and its grounding configuration will be described in detail.
As shown in FIG. 3, the LED unit 40 includes an LED head 41 as an example of an exposure member body, an exposure device frame 42 as an example of a holding member, a roller support member 43, a guide roller 44, and a resin cover 45. And a suspender 48.

The LED head 41 has a plurality of light emitting portions made of LEDs on the lower side in the left-right direction (LED head 4
1 in the longitudinal direction). More specifically, the LED head 41 is arranged according to a predetermined pixel pitch, and is a head structure in which a plurality of LEDs (light emitting elements) that are selectively driven and expose the surface of the photosensitive drum 53 are supported by a support. It is what has. In this specification, the longitudinal direction of the LED head 41 is referred to as a main direction, and is a direction orthogonal to the main direction and the LED exposure direction (see arrow X in FIG. 5), specifically, a direction in which the photosensitive drums 53 are arranged. The front-rear direction is referred to as the sub direction. The exterior of the LED head 41 is made of resin, and discharge from high voltage components such as the scorotron charger 54 is suppressed. Each light emitting unit emits light upon receiving a signal from a control device (not shown) based on data of an image to be formed, and exposes the photosensitive drum 53.

The exposure unit frame 42 is a frame that supports the LED head 41. The exposure device frame 42 is formed by pressing a metal plate into a substantially U-shaped cross section, and has conductivity. The exposure device frame 42 is formed longer than the LED head 41 in the axial direction of the photosensitive drum 53, that is, in the left-right direction. Specifically, the exposure device frame 42 includes a lower plate 42A, a side plate 42B, and an upper plate 4.
2C, a member having a U-shaped cross section extending in the left-right direction is formed. End plates 42D are formed at both ends in the left and right direction of the lower plate 42A (hereinafter simply referred to as “both ends”) by bending the end portions of the lower plate 42A. In the upper plate 42C, an opening 42E that opens to the front side is formed near both ends. An engaging claw 42F extending toward the inner side in the left-right direction of the opening 42E is formed at the opening end on the front side of the opening 42E so as to narrow the opening 42E. The upper surface of the LED head 41 is in close contact with the lower plate 42A of the exposure device frame 42, and is attached and fixed to the exposure device frame 42 by two clips 41A.

The right end of the upper plate 42C of the exposure device frame 42 is pressed to urge the right end portion of the LED head 41 so as to be pulled toward the side frame 15A (for details, the abutting portion 161B of the front guide 161 described later; see FIG. 5). A leaf spring 100 as an example of a member is provided. Leaf spring 1
00 is formed by bending a conductive metal plate into a substantially L shape, and includes a first wall 101 and a second wall 102. Since the plate spring 100 is provided on the exposure device frame 42 in this way, the plate spring 100 moves from the top to the bottom toward the abutting portion 161B described later as the LED unit 40 moves to the exposure position. By doing so, one end of the LED unit 40 (
A main-direction positioning surface 45D), which will be described later, is configured to be pressed against the abutting portion 161B.

The first wall 101 is formed in a flat plate shape, and a through hole 45B (
It is formed with a width that can be inserted into the left resin cover 45). And this first wall 10
1 is inserted from the outside of the through hole 45 </ b> B of the resin cover 45 and the upper plate 4 of the exposure device frame 42.
Fixed to the top surface of 2C.

As shown in FIG. 5, the second wall 102 has a distal end portion 103 and a main body portion 104.
The main body 104 of the second wall 102 has a side frame 15A (first vertical wall A1) so as to gradually approach the exposure unit frame 42 as it goes downward in a state where the first wall 101 is fixed to the exposure unit frame 42. It is inclined with respect to. Further, the distal end portion 103 of the second wall 102 is inclined with respect to the side frame 15A (first vertical wall A1) so as to move away from the exposure device frame 42 as it goes downward. Therefore, when the LED unit 40 is moved from the retracted position to the exposure position, the distal end portion 103 of the second wall 102 and a side frame 1 described later.
When 5A 1st vertical wall A1 contact | abuts, the 2nd wall 102 will be spread outside by this 1st vertical wall A1.

As shown in FIG. 3A, the roller support member 43 is a bracket formed by pressing a conductive metal plate, and is screwed to end plates 42 </ b> D at both ends of the exposure device frame 42. The roller support member 43 is provided with a roller shaft 43A that extends toward the inner side in the left-right direction at the lower end. The roller shaft 43A is a shaft that rotatably supports the guide roller 44, and an engagement groove 43B is formed in the circumferential direction as shown in FIG.

The guide roller 44 is a substantially cylindrical roller as an example of an abutting portion, and maintains a distance between the LED head 41 and the photosensitive drum 53. That is, the rolling surface 44A is formed in a cylindrical shape. The center axis of the rolling surface 44A has a shaft hole 44B that fits with the roller shaft 43A.
Is formed. The guide roller 44 is attached to the roller shaft 43A by engaging the clip 44D with the engaging groove 43B after the shaft hole 44B is inserted into the roller shaft 43A and the washer 44C is further inserted. That is, the direction in which the roller shaft 43 </ b> A extends coincides with the rotation axis direction of the guide roller 44.

As shown in FIG. 2, the guide roller 44 rolls in contact with the circumferential surface 53 </ b> A of the photosensitive drum 53 to define the positional relationship between the LED unit 40 and the photosensitive drum 53, specifically, the light emitting portion of the LED head 41. It defines the interval between the peripheral surfaces 53A. The material constituting the guide roller 44 is not particularly limited, but it is preferable to use a material having an appropriate friction coefficient with the peripheral surface 53A and having excellent wear resistance. For example, a polyamide-based resin can be used. In order not to affect image formation, the guide roller 44 is disposed outside the image forming range (indicated by symbol W in FIG. 5) to which toner is supplied, on the peripheral surface 53A of the photosensitive drum 53. Yes.

As shown in FIG. 3A, the resin cover 45 is a member that covers the metal portions at both ends of the exposure device frame 42. The resin covers 45 provided in total on the left and right are formed symmetrically with each other. The resin cover 45 is made of an insulating resin member, and is formed so as to cover both end faces of the exposure unit frame 42 and a predetermined range from both ends. A guide rib 45 </ b> A extending in the vertical direction protrudes from the outer end of the resin cover 45 in the horizontal direction. The upper end of the guide rib 45A has a substantially triangular outline when viewed from the left and right end sides, and a through hole 45B is formed inside the triangular portion. And the through-hole 45 of the resin cover 45 arrange | positioned at the right side
The first wall 101 of the leaf spring 100 described above is inserted into B (not shown).

The outer surface in the left-right direction of the guide rib 45A is a main direction positioning surface 45D. The main direction positioning surface 45D is for abutting the side frame 15A in the main direction to position the LED unit 40 in the main direction. The front surface of the guide rib 45A is a sub-direction positioning surface 45E. The sub-direction positioning surface 45E is for abutting the side frame 15A in the sub-direction to position the LED unit 40 in the sub-direction.

The suspender 48 is a member that supports the exposure device frame 42 and the LED head 41 in a suspended state. The suspender 48 has a length in the left-right direction equivalent to that of the exposure device frame 42, and is provided with engagement members 48A at two locations corresponding to the two openings 42E. Each of the engaging members 48A is formed with a U-shaped cross-section that opens outward in the left-right direction when viewed from below, and the U-shaped opening 48B has play with the engaging claw 42F. It is designed to engage.

A compression spring 49 as an example of a first urging member is disposed between each engaging member 48 </ b> A and the exposure device frame 42. The compression spring 49 is arranged on the inner side in the left-right direction (the inner side in the longitudinal direction of the exposure member) than the two guide rollers 44. When the engaging member 48A is engaged with the opening 42E and the engaging claw 42F of the exposure device frame 42 with play, and then locked by a retaining member (not shown), the exposure device frame 42 and the LED head 41
Is constantly biased toward the photosensitive drum 53 by the compression spring 49.

Such an LED unit 40 includes a connection link 14A and an LED as shown in FIG.
It is attached to the upper cover 12 via the attachment member 14. Connection link 14A is LE
The connection portion with the D mounting member 14 and the connection portion with each LED unit 40 can be rotated in a side view of FIG. 2, and thus the posture of the LED unit 40 can be freely changed. Therefore, it is easy to engage the LED unit 40 with the side frame 15A.

Each LED unit 40 extends downward from the upper cover 12 when attached to the upper cover 12. As described above, the upper cover 12 can be rotated and opened around the rear hinge 12A, so that the photosensitive drum 53 and the LED unit 40 are located at an exposure position close to each other and a retracted position apart from each other. Relative movement is possible. The LED unit 40 has a guide roller 44 provided at the lower end at the exposure position.
Thus, the distance between the peripheral surface 53A and the LED head 41 is kept constant.

As shown in FIG. 4, the side frame 15 </ b> A corresponds to both end portions of the LED unit 40 where the four LED units 40 are mounted, and the front guide 161 and the rear guide 16.
2 has. The front guide 161 is disposed in front of the sub-direction positioning surface 45E, and the rear guide 162 is disposed behind the sub-direction positioning surface 45E.

The front guide 161 is formed with a rib 161A extending substantially in the vertical direction so as to protrude inward in the horizontal direction. The rib 161A is a guide rib 45A when the LED unit 40 is mounted.
Located in front of. The upper and lower ends of the rib 161A are cylindrical portions 161C that are thicker in the longitudinal direction than the central portion. The cylindrical portion 161C is in contact with the sub-direction positioning surface 45E and serves as a portion for positioning the LED unit 40 in the sub-direction. The front guide 16
An abutting portion 161B, which is an example of a reference portion, is provided along the rib 161A on the rear edge of 1. The abutting portion 161B is a surface on which the main direction positioning surface 45D of the LED unit 40 can come into contact, and the right abutting portion 161B abuts on one end side of the LED unit 40 to regulate the position of the LED unit 40 in the left-right direction. (See FIG. 5). And the abutment part 1
61B and main direction positioning surface 45D are each formed with predetermined smoothness so that it can slide mutually. The abutting portion 161B and the main direction positioning surface 45D may be surface contact or point contact.

The rear guide 162 is provided with an arm 162A extending from the bottom to the top. Arm 1
62A is supported by a metal plate of the side frame 15A so as to be rotatable on a rotation shaft 162B. A torsion spring 162C is provided around the rotation shaft 162B, and an urging force is always applied to the arm 162A counterclockwise in FIG. 4 by the torsion spring 162C.

Both the front guide 161 and the rear guide 162 are made of resin.
Wear due to sliding contact with the D unit 40 is suppressed.

As shown in FIG. 5, the right side frame 15A includes a first vertical wall A1 to which the front guide 161 is fixed, a horizontal wall A2 bent rightward from the upper end of the first vertical wall A1, and a horizontal wall A.
2 and a second vertical wall A3 bent upward from the right end. A through hole 15 </ b> C for engaging the second wall 102 of the leaf spring 100 with the side frame 15 </ b> A in the vicinity of the abutting portion 161 </ b> B of the front guide 161 is formed in the lateral wall A <b> 2. Therefore, this through hole 1
When the second wall 102 of the leaf spring 100 is inserted into 5C and engaged with the first vertical wall A1 of the side frame 15A, the second wall 102 of the leaf spring 100 attaches the side frame 15A to the LED unit 40.
The right end portion of the LED unit 40 (main direction positioning surface 45D
) Is attracted to and abuts against the abutting portion 161B of the front guide 161. That is, the leaf spring 1
The second wall 102 of 00 is the abutting portion 161B of the side frame 15A and the front guide 161.
Is sandwiched between the right end of the LED unit 40 and left and right. At this time, LED
The left end portion of the unit 40 and the abutting portion 16 of the front guide 161 of the left side frame 15A.
A predetermined gap is formed between 1B and 1B.

The left side frame 15A includes a vertical wall A4 to which the front guide 161 is fixed, and a pedestal wall A5 bent rightward from the lower end of the vertical wall A4. And
A coil spring 200 as an example of a second urging member that urges the LED unit 40 in a direction away from the photosensitive drum 53 is provided between the pedestal wall A5 and the exposure unit frame 42 of the LED unit 40. Yes. The coil spring 200 is formed of a conductive member such as metal. Each side frame 15A is electrically grounded. The lower end of the coil spring 200 is fixed to the pedestal portion A5.

The operation and effect of the color printer 1 configured as described above will be described.
As shown in FIG. 1, when the process cartridge 50 of the color printer 1 is replaced or maintained, the upper cover 12 is first rotated upward to open the LED unit 4.
0 is moved from the exposure position to the retracted position.

In the color printer 1 of the present embodiment, since the LED unit 40 can move between the exposure position and the retracted position with respect to the photosensitive drum 53 as described above, it is necessary to position the LED unit 40 with respect to the photosensitive drum 53. is there.

When the maintenance is completed, the upper cover 12 is lowered and closed. At this time, the guide roller 44 at the tip (lower end) of the LED unit 40 is moved to the photosensitive drum 53 as shown in FIG.
It contacts the peripheral surface 53A. Thereby, the distance between the circumferential surface 53A and the light emitting part of the LED head 41 is kept constant.

At this time, as shown in FIG. 4, the guide rib 45 </ b> A is formed by the rib 161 </ b> A of the front guide 161.
And between the arms 162A of the rear guide 162. Since the arm 162A is biased forward by the torsion spring 162C, the guide rib 45A is biased forward.
Thereby, the sub-direction positioning surface 45E of the guide rib 45A comes into contact with the cylindrical portions 161C at both ends of the rib 161A, and the LED unit 40 is positioned in the sub-direction.

At this time, as shown in FIG. 5, the leaf spring 10 provided in the LED unit 40.
The 0 second wall 102 passes through the through hole 15C of the right side frame 15A and engages with the outer surface of the first vertical wall A1 with its tip bent to the right. Accordingly, the leaf spring 100
The right main direction positioning surface 45D of the LED unit 40 by the urging force of the second wall 102
Is pulled to the right and abuts against the abutting portion 161B of the front guide 161, and the LED unit 4
0 is positioned in the main direction.

In the positioning in the main direction as described above, the exposure device frame 42 is moved by the leaf spring 10.
0 and the side frame 15A are electrically grounded, and the coil spring 200
And is electrically grounded through the side frame 15A.

According to the above, the following effects can be obtained in the present embodiment.
The leaf spring 100 urges the right main direction positioning surface 45D of the LED unit 40 so as to be attracted to the abutting portion 161B of the front guide 161 provided on the right side frame 15A. On the other hand, the LED unit 40 can be positioned in the main direction. Furthermore, since the leaf spring 100 is provided only on one end side of the LED unit 40, for example, coil springs having different urging forces are provided on both end sides of the LED unit.
The distortion of the side frame can be suppressed as compared with the structure in which the LED unit is pressed against the side frame by the coil spring having the larger biasing force provided one by one.

By using the leaf spring 100 having elasticity as a pressing member that presses the LED unit 40 against the abutting portion 161B of the side frame 15A, positioning can be performed with a simple structure, so that the cost can be reduced.

Since the abutting portion 161B of the front guide 161 and the main direction positioning surface 45D of the LED unit 40 are slidable, the photosensitive drum 53 is formed in a somewhat elliptical shape within a range of manufacturing errors. In addition, the LED unit 40 can be smoothly moved in the vertical direction, and the guide roller 44 can be reliably kept in contact with the peripheral surface 53A of the photosensitive drum 53. Therefore, the distance between the LED head 41 and the photosensitive drum 53 can be reliably maintained constant.

The exposure unit frame 42 includes a leaf spring 100, a coil spring 200, and a side frame 15A.
Therefore, even when the LED head 41 whose exterior is formed of a resin as in the present embodiment is used, the metal exposure unit frame 42 that is in close contact with the upper surface of the LED head 41 is used. Can be grounded. Thereby, the electric charge generated on the surface of the LED head 41 can be sufficiently removed. Even if a large current flows through the LED head 41 and electromagnetic waves are generated, the exposure device frame 42 is formed larger in the left-right direction than the LED head 41, and a metal side frame is provided on both sides of the LED head 41 in the left-right direction. Since 15A is provided, electromagnetic waves are sufficiently absorbed by these members, and the influence of electromagnetic waves on other devices can be suppressed. In particular, in the present embodiment, the above-described configuration is adopted on both the left and right sides, so that grounding and electromagnetic wave absorption can be sufficiently performed. In this embodiment, since the leaf spring 100 is used for positioning in the main direction, the positioning of the LED head 41, the grounding of the LED head 41, and the shielding of electromagnetic waves can be performed simultaneously. Furthermore, by making the LED head 41 a resin exterior, the LED head 41 can be downsized, the degree of freedom in layout around the photosensitive drum 53 is increased, and the color printer 1 can be downsized.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

In the said embodiment, although the leaf | plate spring 100 as a press member was provided in the LED unit 40,
The present invention is not limited to this. For example, as shown in FIGS. 6 and 7, a leaf spring 110 may be provided on the right side frame 15A. In FIG. 6 and FIG. 7, the same reference numerals are given to the same components as those in the above embodiment, and the description thereof is omitted. Although illustration of the left side frame 15A is omitted, the leaf spring 110 is not provided on the left side frame 15A, as in the embodiment (FIG. 5), and the left side frame 15A A gap is formed between the LED unit 400.

Specifically, the leaf spring 110 shown in FIG. 6 has a structure in which the leaf spring 100 according to the embodiment is turned upside down, and the first wall 111 and the second wall 112 that are substantially the same as those in the embodiment. In addition to the front end portion 113, a fixing portion 114 for fixing the first wall 111 to the side frame 15A is provided. When the leaf spring 110 is fixed to the inner surface of the side frame 15A, the front end portion 161 of the leaf spring 110 is fixed to the side frame 15A.
It is arranged on the inner side of the abutting portion 161B in the left-right direction.

In this structure, the LED unit 400 has a resin cover 450 different from the LED unit 40 according to the embodiment. Specifically, the resin cover 450 is formed with a recess 451 opening downward on the lower surface thereof, thereby forming a protruding wall 452 protruding downward on the outer side in the left-right direction of the resin cover 450.

The protruding wall 452 is sandwiched between the abutting portion 161B of the front guide 161 and the distal end portion 113 of the leaf spring 110 at the exposure position, so that the outer surface thereof comes into contact with the abutting portion 161B. Yes. Thereby, the LED unit 400 can be positioned in the main direction.

Further, as shown in FIG. 7, the leaf spring 110 may be fixed to the outer surface of the side frame 15A. In this case, the protruding wall 452 of the resin cover 450 described above is connected to the distal end portion 11 of the leaf spring 110.
3 and the outer surface of the side frame 15 </ b> A, the protruding wall 452 becomes the leaf spring 110.
And is brought into contact with the outer surface of the side frame 15A. That is, in this embodiment, the reference portion is the outer surface of the side frame 15A. Thereby, the LED unit 400
Can be positioned in the main direction.

In the embodiment, the leaf spring 100 is used as the pressing member, but the present invention is not limited to this, and may be a torsion spring, for example. Moreover, you may employ | adopt a disc spring, a leaf | plate spring, etc. as a 1st biasing member or a 2nd biasing member.

In the said embodiment, although the leaf | plate spring 100 which has elasticity (flexibility) as a press member was employ | adopted, this invention is not limited to this.

In the said embodiment, although the form which has two or more LED was illustrated as a several light emission part, in order to form this several light emission part, one light emitting element like LED may be sufficient. For example, one backlight such as a fluorescent lamp may be prepared, and an optical shutter of liquid crystal or PLZT elements arranged in a line in the left-right direction may be provided outside the backlight. That is, a plurality of light emitting units arranged in a row can be formed by combining one light emitting element and a row of optical shutters. Also,
The light emitting units may be arranged in a plurality of rows rather than arranged in one row in the left-right direction. Furthermore, the light emitting element is not limited to an LED, and may be an EL (electroluminescence) element or a phosphor.

The side frames 15 </ b> A (main body frames 15) arranged on both sides of the photosensitive drum 53 may be the framework of the color printer 1, or a drawer frame in which a plurality of process cartridges 50 are collectively attached to and detached from the color printer 1. It doesn't matter.

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 an enlarged view of the LED unit and process cartridge of FIG. (A) is an exploded perspective view of an LED unit, and (b) is an enlarged perspective view of a guide roller. It is a side view which shows the positional relationship of an LED unit and a side plate. It is the figure which looked at the photosensitive drum and LED unit from back. It is a figure which shows the modification which provided the leaf | plate spring in the inner surface of the side frame. It is a figure which shows the modification which provided the leaf | plate spring in the outer surface of the side frame.

DESCRIPTION OF SYMBOLS 1 Color printer 15 Main body frame 15A Side frame 40 LED unit 41 LED head 42 Exposure device frame 45 Resin cover 45D Main direction positioning surface 49 Compression spring 53 Photosensitive drum 101 1st wall 102 2nd wall 103 Tip part 161 Front guide 161B Abutting Part

Claims (11)

  An exposure member having a plurality of light emitting portions, extending in the longitudinal direction, and exposing the photosensitive drum;
  A first frame facing one end in the longitudinal direction of the exposure member and having a reference portion;
  A leaf spring that has a proximal end fixed to the first frame and a distal end that engages with one end of the exposure member, and presses the one end of the exposure member toward the reference portion; An exposure apparatus comprising:
  The exposure apparatus according to claim 1, further comprising no member that presses the other end portion of the exposure member opposite to the one end portion in the longitudinal direction.
  A second frame facing the other end of the exposure member;
  3. The exposure apparatus according to claim 2, wherein a gap is formed between all surfaces of the second frame facing the other end of the exposure member in the longitudinal direction and the other end of the exposure member. .
  The reference portion of the first frame protrudes toward the center side of the exposure member in the longitudinal direction from a portion where a base end portion of the leaf spring of the first frame is fixed. The exposure apparatus according to any one of the above.
The leaf spring further includes a connecting portion that extends in the longitudinal direction and connects the distal end portion and the proximal end portion, and the distal end portion and the connecting portion are bent in a substantially L shape. The exposure apparatus according to claim 4.
  A recess is formed at one end of the exposure member,
  6. The exposure apparatus according to claim 1, wherein a distal end portion of the leaf spring is engaged with a surface that forms the concave portion and faces the center side of the exposure member in the longitudinal direction.
  One end of the exposure member has a base, and a protrusion protruding from the base in a direction parallel to the optical axis of light emitted from each light emitting portion of the exposure member,
  The protruding portion has a facing surface facing the reference portion of the first frame in the longitudinal direction, and a surface opposite to the facing surface,
  The tip of the leaf spring presses the opposite surface of the protrusion to the reference portion side of the first frame,
  The exposure apparatus according to claim 1, wherein an opposing surface of the protruding portion is in contact with the reference portion.
The exposure apparatus according to claim 1, wherein the exposure member has at least an LED head.
  The exposure apparatus according to claim 8, wherein the LED head has a resin exterior.
The exposure apparatus according to claim 1, wherein the leaf spring is configured to be grounded.
  The device body;
  A fixing device;
  The photosensitive drum;
  An image forming apparatus comprising: the exposure apparatus according to claim 1.