JP2023092667A - Exposure device and image formation device - Google Patents

Abstract

To solve the problem that when a substrate mounted with an LED array is fixed to a holder in an exposure device, a silicone resin and a UV curable adhesive are used, but the exposure device requires a fixing jig until being cured, and the substrate cannot be repaired.SOLUTION: An exposure device has a substrate 103 having a mounting surface 103a where an LED array 107 is arranged, a rod lens array 104 for condensing light from the LED array 107, and a holder 102 which has an upper plane 102c brought into contact with the mounting surface 103a and holds the substrate 103 and the rod lens array 104, wherein a weakly adhesive silicone resin 111 is coated to a region where the upper plane 102c and the mounting surface 103a are brought into contact with each other.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus, and more particularly to the structure of an exposure device that exposes an image carrier.

Some conventional exposure apparatuses have a structure in which a substrate on which an LED array is mounted is fixed to a holder by, for example, silicone resin applied to the side of the substrate opposite to the LED mounting surface (see, for example, Patent Document 1). In another example, a substrate is strongly adhered to a holder with a UV curable adhesive (see, for example, Patent Document 2).

JP 2018-183945 A (page 8, FIG. 7)

Japanese Patent Application Laid-Open No. 2018-1569 (page 9, FIG. 5)

However, in the former case, it is necessary to keep holding the substrate in the holder with a jig or the like until the silicone resin hardens, which poses a problem of poor workability. For example, there was a problem that the board could not be repaired.

An exposure apparatus according to the present invention comprises:
A substrate having a mounting surface on which a light emitting element is arranged, a lens for condensing light from the light emitting element, and a contact surface that contacts the mounting surface, and hold the substrate and the lens. a holder;
A silicon resin is provided in a region where the contact surface and the mounting surface are in contact with each other.

According to the exposure apparatus of the present invention, since the mounting surface of the substrate and the contact surface of the holder can be in close contact with each other, there is no need to keep holding the substrate on the holder with a jig or the like until the silicone resin hardens. Since the holder can be separated again, workability during manufacturing can be improved.

1 is a main configuration diagram schematically showing the main configuration of an image forming apparatus of Embodiment 1 having an exposure device according to the present invention, viewed from the front; FIG. FIG. 2 is a perspective view of a main part of an LED head as an exposure device as seen obliquely from above; FIG. 3 is a perspective view of a main part of the LED head as seen obliquely from below; 1 is a perspective view showing a cross section of an LED head, where (a) is a perspective view of the LED head cut at the center in the longitudinal direction (Y-axis direction), and (b) is a partially enlarged view of the cut section; FIG. 4C is a partially enlarged view further enlarging the portion enclosed by the dotted line in FIG. FIG. 10 is a diagram for explaining the substrate-contacting convex portion, and is a perspective view of the main part near the cut portion before disposing the substrate and the insulating film. FIG. 10 is a diagram for explaining the substrate-contacting convex portion, and is a partial plan view of the holder before the substrate and the insulating film are arranged. FIG. 4 is a cross-sectional view at a position where a substrate-contacting projection is formed in the central portion in the longitudinal direction of the LED head; It is a figure where it uses for description of the manufacturing method of an LED head. FIG. 10A is a diagram for explaining Modification 1, and FIG. 11A is a perspective view of a substrate mounted with an LED array and wire bonding for electrically connecting the LED array and the substrate, with the side on which the LED array is arranged facing upward; FIG. 11B is a partial plan view of a holder according to Modification 1. FIG. FIG. 10 is a diagram for explaining Modification 2, and is a partial plan view of a holder of Modification 2;

Embodiment 1.
FIG. 1 is a schematic view of the configuration of main parts of an image forming apparatus according to Embodiment 1, which is equipped with an exposure device according to the present invention, viewed from the front.

The image forming apparatus 11 is configured as, for example, an electrophotographic color printer, and includes four independent image forming units 12K, 12Y, 12M, and 12C (sometimes simply referred to as the image forming unit 12 when there is no particular need to distinguish them). ) are arranged in order from the upstream side along the conveying direction (arrow A direction) of recording paper 30 as a recording medium. The image forming unit 12K forms a black (K) image, the image forming unit 12Y forms a yellow (Y) image, the image forming unit 12M forms a magenta (M) image, and the image forming unit 12C A cyan (C) image is formed. In addition to the recording paper 30, OHP paper, envelopes, copying paper, special paper, and the like can be used as the recording medium.

The image forming unit 12K includes a photosensitive drum 13K, a charging roller 14K that uniformly charges the surface of the photosensitive drum 13K, and a toner (not shown) as a developer applied to the electrostatic latent image formed on the surface of the photosensitive drum 13K. , a developing roller 16K for forming a toner image, a toner supplying roller 18K pressed against the developing roller 16K, and a residual toner removing blade 27K for removing residual toner adhering to the photosensitive drum 13K after transfer. there is Similarly, the image forming unit 12Y includes a photosensitive drum 13Y, a charging roller 14Y, a developing roller 16Y, a toner supply roller 18Y, and a residual toner removing blade 27Y. The image forming unit 12M includes a photosensitive drum 13M. , a charging roller 14M, a developing roller 16M, a toner supply roller 18M, and a residual toner removing blade 27M are arranged. A residual toner removal blade 27C is provided.

Each of the toner supply rollers 18K, 18Y, 18M, and 18C (which may be simply referred to as the toner supply roller 18 when there is no particular need to distinguish them) is detachably attached to the main body of the image forming unit 12. Developing rollers 16K, 16Y, 16M and 16C (especially If there is no need to distinguish between them, they may simply be referred to as developing rollers 16). Developing blades 19K, 19Y, 19M, and 19C (which may be simply referred to as developing blades 19 when there is no particular need to distinguish between them) are in pressure contact with the developing rollers 16K, 16Y, 16M, and 16C, respectively. The developing blade 19 forms a thin layer of toner supplied from the toner supply roller 18 on the developing roller 16 . Although the toner cartridge 20 is detachably attached to the main body of the image forming unit 12 here, it may be integrally formed.

Above the photoreceptor drums 13K, 13Y, 13M, and 13C in the image forming units 12K, 12Y, 12M, and 12C (which may be simply referred to as photoreceptor drums 13 when there is no particular need to distinguish them), there are corresponding LED heads 15K, 15Y, 15M, and 15C (which may be simply referred to as LED heads 15 when there is no particular need to distinguish them) are detachably arranged at positions facing the photosensitive drums 13K, 13Y, 13M, and 13C. is set. Each LED head 15 exposes the photosensitive drum 13 according to the image data of the corresponding color to form an electrostatic latent image. Incidentally, the LED head 15 will be described later in detail.

A transfer unit 21 is arranged below each photosensitive drum 13 of the four image forming units 12 . The transfer unit 21 is stretched by transfer rollers 17K, 17Y, 17M, and 17C (which may be simply referred to as transfer rollers 17 when there is no particular need to distinguish them), a transfer belt driving roller 21a, and a transfer belt driven roller 21b. A transfer belt 26 is arranged so as to be able to travel in the direction of arrow A in FIG. Each transfer roller 17 is arranged in pressure contact with the corresponding photoreceptor drum 13 via the transfer belt 26, and in this nip portion, the recording paper 30 is charged to a polarity opposite to that of the toner, and the corresponding photoreceptor drum 13 is charged. The formed toner images of respective colors are sequentially superimposed and transferred onto the recording paper 30 .

A paper feeding mechanism for feeding paper to the transfer belt 26 is arranged in the lower portion of the image forming apparatus 11 . The paper feed mechanism includes a hopping roller 22, a registration roller pair 23, a paper storage cassette 24, and a paper color measuring section 25 for measuring the color of the paper in the paper storage cassette 24, and the like.

Further, a fixing device 28 is provided on the discharge side of the recording paper 30 by the transfer belt 26 . The fixing device 28 has a heating roller and a backup roller, and is a device that fixes the toner transferred onto the recording paper 30 by applying pressure and heat. A discharge roller (not shown), a paper stacker unit 29, and the like are provided.

It should be noted that the X, Y, and Z axes in FIG. The Y-axis is taken in the direction of the rotation axes of 13M and 13C, and the Z-axis is taken in a direction orthogonal to these two axes. Also, when the X, Y, and Z axes are shown in other drawings to be described later, these axial directions indicate the common direction. That is, the XYZ axes in each figure indicate the arrangement direction when the depicted portion in each figure constitutes the image forming apparatus 11 shown in FIG. Also, here, it is assumed that the Z-axis is arranged in a substantially vertical direction.

A printing operation in the image forming apparatus 11 configured as described above will be described. First, the recording paper 30 in the paper storage cassette 24 is fed out by the hopping roller 22, sent to the registration roller pair 23 to correct skew, and then sent from the registration roller pair 23 to the transfer belt 26, where the transfer is performed. As the belt 26 runs, the sheets are sequentially conveyed to the image forming units 12K, 12Y, 12M, and 12C.

On the other hand, in each image forming unit 12, the surface of the photosensitive drum 13 is charged by a charging roller 14 (which may be simply referred to as charging roller 14 when there is no particular need to distinguish), and then the corresponding LED head 15 is charged. and the exposure forms an electrostatic latent image on the surface. The toner thinned on the developing roller 16 is electrostatically adhered to the portion where the electrostatic latent image is formed to form a toner image of the corresponding color. The toner images formed on the photoreceptor drums 13 are sequentially superimposed and transferred onto the recording paper 30 by the corresponding transfer rollers 17 to form a color toner image on the recording paper 30 . Toner remaining on each photoreceptor drum 13 after transfer is removed by a residual toner removing blade 27 .

The recording paper 30 on which the color toner image is formed is sent to the fixing device 28 . In this fixing device 28, the color toner image is fixed on the recording paper 30 to form a color image. The recording paper 30 on which the color image is formed is conveyed along the paper guide 31 by a discharge roller (not shown) and discharged to the paper stacker section 29 . A color image is formed on the recording paper 30 through the process described above. Residual toner adhering to the transfer belt 26 is scraped off by the belt cleaning blade 32 and stored in the belt cleaner container 33 .

Next, the configuration of the LED head 15 will be further described.

FIG. 2 is a perspective view of essential parts of an LED head 15 as an exposure device viewed obliquely from above, and FIG. 3 is a perspective view of essential parts of the same LED head 15 viewed obliquely from below. 4A and 4B are perspective views showing a cross section of the LED head 15, FIG. ) is a partially enlarged view of the cross section, and FIG. 1(c) is a partially enlarged view further enlarging the portion enclosed by the dotted line in FIG. 1(b).

In the LED head 15 shown in FIG. 4, there are cases where the front, back, left, right, and top and bottom directions of the LED head 15 are specified when viewed from the direction of the arrow B (the negative direction of the Y axis).

As shown in these figures, the LED head 15 mainly comprises a holder 102, a substrate 103, a rod lens array 104 and an insulating film 105. FIG. The holder 102 is manufactured by injection molding of liquid crystal polymer, and has a rectangular parallelepiped box shape with an open top (Z-axis + direction) and a U-shaped cross section. is formed with a slit 102a extending in the longitudinal direction (Y-axis direction). Inside the left side wall portion 102L and the right side wall portion 102R of the holder 102, substrate abutting convex portions 102b are formed.

5 and 6 are diagrams for explaining the substrate abutting convex portion 102b, FIG. 5 is a perspective view of the main part near the cut portion before the substrate 103 and the insulating film 105 are arranged, and FIG. , a partial plan view of the holder 102 before placing the substrate 103 and the insulating film 105;

As shown in these drawings, a plurality of substrate-contacting protrusions 102b are arranged on both sides of the slit 102a at substantially equal intervals in the longitudinal direction so as to face each other. It is desirable that the maximum height of the surface roughness of the upper flat surface 102c as the contact surface of each substrate contact protrusion 102b is about 30 μm or less.

The substrate 103 is a substantially rectangular FR-4 printed circuit board extending in the longitudinal direction, and has an LED array 107 in which a plurality of light emitting elements are arranged in the longitudinal direction on its mounting surface 103a. , connector 108 and the like are mounted. The LED array 107 and the substrate 103 are electrically connected by wire bonding 109 provided on the mounting surface 103a.

The substrate 103 is inserted from above into the holder 102, and positioned with its mounting surface 103a abutting against the upper flat surface 102c of each substrate abutting protrusion 102b. It is desirable that the surface roughness of the portion of the mounting surface 103a that abuts on the upper flat surface 102c has a maximum height of about 30 μm or less.

A weakly adhesive silicone resin 111 as a silicone resin is applied to the upper flat surface 102c of the substrate contacting protrusion 102b, and the substrate 103 is in contact with the upper flat surface 102c so as to crush the weakly adhesive silicone resin 111. . The weakly adhesive silicone resin 111 has a tensile shear adhesive strength of about 2.0 MPa or less, and does not cause material breakage when the substrate 103 is separated from the upper flat surface 102c of the substrate abutting projection 102b. have strength.

The weakly adhesive silicone resin 111 preferably has the property of curing at room temperature, for example, KE-3446-W available from Shin-Etsu Chemical Co., Ltd. Also, the weakly adhesive silicone resin 111 may be replaced with another resin having weak adhesiveness and room temperature curing characteristics. Here, normal temperature means an environmental temperature of 15° C. to 35° C., for example.

The rod lens array 104 as a lens fitted in the slit 102a of the holder 102 is provided with an adhesive (not shown) so that the distance between the upper end surface 104a on which light is incident and the surface of the LED array 107 is optimal in terms of the characteristics of the rod lens array 104. , and functions as a converging lens that converges light emitted from the LED array 107 . A gap between the holder 102 and the rod lens array 104 is sealed with a sealing silicone resin 106 to prevent light and foreign matter from entering the holder 102 .

At both ends of the holder 102 in the front-rear direction (Y-axis direction), as shown in FIG. A through hole 102d for positioning and a cam mechanism 102e for positioning in the height (Z-axis) direction are provided. Alternatively, the holder 102 may be manufactured by using other materials such as resin and by other manufacturing methods such as cutting.

FIG. 7 is a cross-sectional view of the LED head 15 at the central portion in the longitudinal direction, at the position where the board contact protrusion 102b is formed. As shown in the figure, when the mounting surface 103a of the substrate 103 abuts against the upper flat surface 102c of the substrate abutting projection 102b, the weak adhesive silicone resin 111 applied to the upper flat surface 102c protrudes inward.

If the protruding weak adhesive silicone resin 111 interferes with the wire bonding 109 applied to the mounting surface 103a of the substrate 103, the wire bonding 109 may break when the substrate 103 is peeled off from the holder 102. There is For this reason, it is desirable that the distance L from the overhanging portion of the substrate contacting projection 102b to which the weakly adhesive silicone resin 111 is applied to the wire bonding 109 is 1 mm or more.

The insulating film 105 is an insulating film such as PET, and protects the substrate 103 from electrostatic discharge and invasion of foreign matter. Therefore, the sealing silicone resin 112 is applied so as to hold the insulating film 105 at a predetermined distance above the substrate 103 and seal the gap between the insulating film 105 and the holder 102 .

Next, a method of manufacturing the LED head 15 will be described, and how the substrate 103 is held within the holder 102 will be described. FIG. 8 is a diagram for explaining a method of manufacturing the LED head 15. FIG.

First, the rod lens array 104 is fixed to the holder 102 with an adhesive (not shown) at a position where the distance from the LED array 107 is optimal as described above, and the gap between the holder and the rod lens array is sealed with sealing silicone resin 106. stop. Next, as shown in FIG. 8, a dispenser nozzle 150 is used to apply a weak adhesive silicone resin 111 to the upper flat surface 102c of the substrate abutting projection 102b, the substrate 103 is inserted into the holder 102, and the weak adhesive is applied. The mounting surface 103a is brought into contact with the upper flat surface 102c of the substrate contacting protrusion 102b so as to crush the silicone resin 111. As shown in FIG.

The weakly adhesive silicone resin 111 is in a liquid state before curing, and the surface roughness of the upper flat surface 102c of the substrate contacting protrusion 102b and the mounting surface 103a of the substrate 103 facing the upper flat surface 102c is the maximum height. Since the surface of the holder 102 and the substrate 103 is approximately 30 μm or less and has a high degree of flatness, the fine irregularities on the surfaces of the holder 102 and the substrate 103 are filled with the silicone resin.

Since the holder 102 and the substrate 103 are brought into close contact with each other through the silicone resin, an intermolecular force acts, and the substrate 103 and the holder 102 are weakly fixed in contact even before the silicone resin hardens. In this state, the insulating film 105 is placed above the substrate 103, the periphery is sealed with the sealing silicone resin 112, and left to stand until it hardens.

As described above, in the manufacturing process of the LED head 15 of the present embodiment, the holder 102 and the substrate 103 are in close contact with each other through the weakly adhesive silicone resin 111, so that the intermolecular force causes weak adhesion. Even before the silicone resin 111 hardens, it is weakly fixed in a contact state, so it is possible to leave it as it is until the weakly adhesive silicone resin 111 hardens.

(Modification 1)
FIG. 9 is a diagram for explaining Modification 1. FIG. 9A shows a substrate 103 mounted with an LED array 107 and wire bonding 109 for electrically connecting the LED array 107 and the substrate 103 to the LEDs. It is a perspective view of the mounting surface 103a on which the array 107 is arranged, and is a partial plan view of the holder 202 of the first modification.

As shown in FIG. 9A, in the substrate 103 here, a plurality of wire bonds 109 are alternately arranged on both sides of the LED array 107 extending in the longitudinal direction (Y-axis direction). shall be In such a case, when the substrate 103 is placed on the holder 202 shown in FIG. It is desirable that the contact area 155 (the area surrounded by the dotted line in the figure) including the periphery is separated from the portion where the wire bonding 109 is arranged.

For this reason, in the holder 202 of Modification 1, when the substrate 103 is placed, the upper flat surface 102c of the substrate contact projection 102b faces the respective contact areas 155 of the substrate 103 (Fig. As shown in b), substrate contacting protrusions 102b are alternately formed in the longitudinal direction inside each of the left side wall portion 102L and the right side wall portion 102R.

For example, assuming that the upper flat surface 102c of the substrate contact projection 102b reaches the edge of the contact area 155, it is desirable that the shortest distance between the contact area 155 and the wire bonding 109 is 1 mm or more.

Since the LED head 15 of the modified example 1 is formed as described above, the contact region 155 is separated from the portion where the wire bonding 109 is arranged, so that the upper plane 102c of the substrate contact convex portion 102b When the substrate 103 abuts on the upper plane 102c and the weak adhesive silicone resin 111 (see FIG. 8) applied to the upper flat surface 102c protrudes inward, interference with the wire bonding 109 arranged on the substrate 103 can be avoided. I can.

(Modification 2)
FIG. 10 is a diagram for explaining Modification 2, and is a partial plan view of holder 252 of Modification 2. As shown in FIG.

In the holder 252 of Modification 2, the longitudinal direction (Y A stepped portion 252b extending in the axial direction) is formed on the upper flat surface 252c for mounting the substrate 103 thereon.

Therefore, when mounting the substrate 103 shown in FIG. 9A, for example, on this holder 252, the upper flat surface 252c serving as the contact surface is positioned away from the portion where the wire bonding 109 is arranged. A weakly adhesive silicone resin 111 (see FIG. 8) is applied in the application area 156 facing the area 155 .

In this case, assuming that the applied weakly adhesive silicone resin 111 reaches the edge of the contact area 155, it is desirable that the shortest distance between the contact area 155 and the wire bonding 109 is 1 mm or more.

Since the LED head 15 of Modified Example 2 is formed as described above, the portion to which the weakly adhesive silicone resin 111 is applied is separated from the portion where the wire bonding 109 is arranged, so that the stepped portion 252b When the substrate 103 contacts the upper flat surface 252c of the substrate 103 and the weak adhesive silicone resin 111 applied to the upper flat surface 252c protrudes inward, interference with the wire bonding 109 provided on the substrate 103 can be avoided. .

As described above, according to the LED head 15 of the present embodiment, since the holder 102 and the substrate 103 are in close contact with each other through the weak adhesive silicone resin 111 in the manufacturing process, the intermolecular force causes weak adhesion. Even before the adhesive silicone resin 111 hardens, it is weakly fixed in a state of contact, so it is possible to leave it as it is until the weakly adhesive silicone resin 111 hardens. Therefore, the substrate can be fixed to the holder abutting portion without using the biasing jig, and workability is improved.

In addition, since the weak-adhesive silicone resin has an adhesive strength that does not cause material destruction, the substrate 103 and the holders 102, 202, 252 can be separated, and the refurbishment is easier than in the case of strong adhesion with a UV curable adhesive or the like. improves. Furthermore, since the weakly adhesive silicone resin 111 does not interfere with the wire bonding 109, damage to the substrate 103 can be prevented when the substrate 103 is peeled off from the holders 102, 202, 252 for repair.

In this embodiment, a color printer is used as an image forming apparatus, but the present invention can also be applied to a monochrome printer, copier, facsimile machine, and a multifunction machine combining these.

11 image forming apparatus 12 image forming unit 13 photoreceptor drum 14 charging roller 15 LED head 16 development roller 17 transfer roller 18 toner supply roller 19 development blade 20 toner cartridge 21a transfer belt drive roller 21b transfer belt driven roller 22 hopping roller 23 registration roller pair 24 paper storage cassette 25 paper color measuring section 26 transfer belt 27 residual toner removing blade 28 fixing device 29 paper stacker section 30 recording paper 31 paper guide, 32 belt cleaning blade, 33 belt cleaner container, 102 holder, 102L left side wall portion, 102R right side wall portion, 102a slit, 102b substrate contact projection, 102c upper plane, 102d through hole, 102e cam mechanism, 103 Substrate 103a Mounting surface 104 Rod lens array 105 Insulating film 106 Sealing silicone resin 107 LED array 108 Connector 109 Wire bonding 111 Weak adhesive silicone resin 112 Sealing silicone resin 150 Dispenser nozzle 155 contact area, 156 application area, 202 holder, 252 holder, 252b stepped portion, 252c top plane.

Claims (12)

a substrate having a mounting surface on which the light emitting element is arranged;
a lens that collects light from the light emitting element;
a holder that has a contact surface that contacts the mounting surface and holds the substrate and the lens;
An exposure apparatus, wherein silicone resin is provided in a region where the contact surface and the mounting surface contact each other. 2. An exposure apparatus according to claim 1, wherein said silicone resin is a weakly adhesive silicone resin capable of separating said contact surface and said mounting surface without material destruction. 2. The abutting surfaces are disposed so as to abut against the mounting surfaces at both ends of the substrate in the lateral direction at a predetermined interval in the longitudinal direction of the substrate. 3. The exposure apparatus according to 2. 4. An exposure apparatus according to claim 3, wherein said contact surfaces are arranged at positions facing each other in the lateral direction of said substrate. 4. The exposure apparatus according to claim 3, wherein the contact surfaces are alternately arranged in a zigzag pattern in the longitudinal direction of the substrate. 6. An exposure apparatus according to claim 4, wherein said silicone resin is provided on the entire region of said contact surface. The substrate is electrically connected to the light emitting element by wire bonding applied to the mounting surface, and the contact surface is arranged at a position separated from the wire bonding of the held substrate by a predetermined distance or more. 7. An exposure apparatus according to any one of claims 1 to 6, characterized in that the exposure apparatus comprises: 3. The contact surface according to claim 1, wherein the contact surface is arranged so as to contact substantially the entire length of the substrate in the longitudinal direction with the mounting surfaces at both ends of the substrate in the lateral direction. Exposure equipment. The substrate is electrically connected to the light emitting element by wire bonding applied to the mounting surface, and the silicone resin is applied to the contact surface separated from the wire bonding of the held substrate by a predetermined distance or more. 9. The exposure apparatus according to claim 8, wherein the exposure apparatus is provided at an upper position. 10. The exposure apparatus according to any one of claims 1 to 9, wherein the surface roughness of said contact surface has a maximum height of 30 [mu]m or less. 10. An exposure apparatus according to claim 7, wherein said predetermined distance is 1 mm. An image forming apparatus comprising the exposure device according to any one of claims 1 to 11.

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