Exposure device and lens array unit

Abstract

To enable stray light generated in an optical system to be cut, to thereby enable the quality of an exposure device to be improved.SOLUTION: An exposure device comprises: a substrate which has a plurality of light emission elements; a first lens array in which a plurality of first lens elements are arrayed; a second lens array 64 in which a plurality of second lens elements are arrayed; and a light shielding member which is arranged between the first and second lens arrays and has a plurality of opening portions formed in such a manner that the opening portions penetrate correspondingly to the first and second lens elements. Each opening portion includes first and second openings and wall surfaces w1, w2 which are formed in such a manner that the openings extend between the first and second openings. Wall portions are formed in the wall surfaces w1, w2 and a diameter d4 of the second opening is smaller than a diameter d1 of the first opening. Stray light which is generated by reflection light on the wall surface w2 of the opening can be cut. Consequently, the quality of the exposure device can be improved.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exposure device and an image forming apparatus. [Background technology]

[0002] Conventionally, image forming devices such as printers, copiers, facsimile machines, and multifunction devices, for example, printers, are provided with an image forming unit, in which the surface of a photosensitive drum, which has been uniformly charged by a charging roller, is exposed by an exposure device, for example, an LED head, to form an electrostatic latent image, which is then developed with toner to form a toner image of each color, and the toner image is transferred to paper by a transfer roller.The toner image is then fixed to the paper in a fixing device, thereby forming an image and printing.

[0003] The LED head is provided with an optical system formed by abutting and stacking a first light-shielding member, a first lens array (MLA), a second light-shielding member, and a second lens array so that their optical axes are aligned (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-202516 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional LED head, stray light occurs due to light reflected from the wall surface of the through hole in the second light-blocking member disposed between the first and second lens arrays, which reduces the quality of the LED head.

[0006] The present invention aims to provide an exposure device and an image forming device that can solve the problems of the conventional LED heads, cut out stray light generated in the optical system, and improve quality. [Means for solving the problem]

[0007] To this end, the exposure apparatus of the present invention comprises a substrate having a plurality of light-emitting elements, a first lens array in which a plurality of first lens elements are arranged to focus the light from the light-emitting elements and emit the light, a second lens array arranged opposite the first lens array and in which a plurality of second lens elements are arranged to focus the light emitted from the first lens elements and emit the light, and a light-shielding member arranged between the first and second lens arrays and having a plurality of circular openings formed therethrough corresponding to each of the first and second lens elements.

[0008] The plurality of openings include a first opening formed opposite the first lens element, a second opening formed opposite the second lens element, and a wall surface formed extending between the first and second openings.

[0009] A wall portion is formed protruding from the wall surface, and the diameter of the second opening is smaller than the diameter of the first opening. [Effects of the Invention]

[0010] According to the present invention, the exposure device comprises a substrate having a plurality of light-emitting elements, a first lens array in which a plurality of first lens elements are arranged to focus the light from the light-emitting elements and emit the light, a second lens array arranged opposite the first lens array and in which a plurality of second lens elements are arranged to focus the light emitted from the first lens elements and emit the light, and a light-shielding member arranged between the first and second lens arrays and having a plurality of openings each having a circular shape, formed to pass through the member in correspondence with each of the first and second lens elements.

[0011] The plurality of openings include a first opening formed opposite the first lens element, a second opening formed opposite the second lens element, and a wall surface formed extending between the first and second openings.

[0012] A wall portion is formed protruding from the wall surface, and the diameter of the second opening is smaller than the diameter of the first opening.

[0013] In this case, the multiple openings include a first opening formed opposite the first lens element and a second opening formed opposite the second lens element, and a wall portion is formed on the wall surface extending between the first and second openings, and the diameter of the second opening is made smaller than the diameter of the first opening, so that reflected light generated on the wall surface of the opening can be cut and prevented from becoming a stray light component.

[0014] Therefore, the quality of the exposure apparatus can be improved. [Brief explanation of the drawings]

[0015] [Figure 1] 5 is a conceptual diagram of a through hole formed in a second light-shielding member in the embodiment of the present invention. FIG. [Figure 2] 1 is a schematic diagram of a printer according to an embodiment of the present invention. [Figure 3] 1 is a perspective view of an LED head according to an embodiment of the present invention, seen obliquely from above. [Figure 4] 1 is a perspective view of an LED head according to an embodiment of the present invention, viewed obliquely from below. [Figure 5] 1 is an exploded perspective view of an LED head according to an embodiment of the present invention. [Figure 6] 4 is a cross-sectional view taken along the line AA in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, in which a printer as an image forming apparatus will be described.

[0017] FIG. 2 is a schematic diagram of a printer according to an embodiment of the present invention.

[0018] In the figure, 10 is the printer, Cs is the housing of the printer 10, and Bd is the main body of the printer 10, i.e., the device main body. A paper feed cassette 11 serving as a medium storage section is disposed at the bottom of the device main body Bd, and paper P as a medium is placed in a stacker St1 of the paper feed cassette 11. A paper feed mechanism 12 for separating and feeding paper P one sheet at a time is disposed adjacent to the front end of the paper feed cassette 11. The paper P can be cut paper, overhead projector paper, envelopes, copy paper, special paper, etc.

[0019] The paper feed mechanism 12 comprises a hopping roller 13 as a feeding member and a separation device not shown. The paper P separated one by one by the paper feed mechanism 12 and fed to a paper transport path Rt1 as a medium transport path is sent to a transport roller pair m1 as a transport member, and then supplied to image forming units 16Bk, 16Y, 16M, 16C as image forming sections that form images in each of the colors black, yellow, magenta, and cyan.

[0020] Each of the image forming units 16Bk, 16Y, 16M, and 16C is detachably mounted on the apparatus main body Bd and includes a photosensitive drum 31 as an image carrier. An LED head 22 as an exposure device is disposed opposite each of the photosensitive drums 31 in correspondence with each of the image forming units 16Bk, 16Y, 16M, and 16C.

[0021] Furthermore, each of the image forming units 16Bk, 16Y, 16M, and 16C is provided with a toner cartridge 29 as a developer container that contains toner as a developer, which is detachably mounted on the main body of the image forming units 16Bk, 16Y, 16M, and 16C, i.e., a unit main body 28. The unit main body 28 is formed below the toner cartridge 29 and includes a toner storage section 30 that stores toner supplied from the toner cartridge 29, the photosensitive drum 31, a charging roller 32 that serves as a charging device that uniformly charges the surface of the photosensitive drum 31, a developing roller 33 that serves as a developer carrier that holds toner, a supply roller 34 that serves as a developer supply member that supplies toner in the toner storage section 30 to the developing roller 33, a developing blade Db that serves as a developer layer regulating member that uniformly thins the toner supplied to the developing roller 33, a first cleaning device C1 that removes toner from the photosensitive drum 31, and a static eliminator 37 that neutralizes static electricity from the surface of the photosensitive drum 31. The first cleaning device C1 includes a cleaning blade b1 as a cleaning member that scrapes off and removes toner adhering to the photosensitive drum 31. The developing roller 33, the supply roller 34, and the developing blade Db constitute a developing unit.

[0022] The photosensitive drum 31 is rotatably disposed, has a gear at one end, receives rotation from a drive motor (drum motor) (not shown) serving as a drive unit for image formation, and is rotated in the direction of the arrow.

[0023] The charging roller 32 is rotatably disposed in contact with the photosensitive drum 31, and is rotated in the direction of the arrow as the photosensitive drum 31 rotates.

[0024] The developing roller 33 has a gear at one end, is disposed so as to be freely rotatable, and receives rotation from the photosensitive drum 31, causing it to rotate in the direction of the arrow.

[0025] The supply roller 34 has a gear at one end, is disposed so as to be freely rotatable, receives rotation from the developing roller 33, and is rotated in the direction of the arrow.

[0026] The LED head 22 is composed of LEDs 69 (described later) as light-emitting elements arranged in the main scanning direction of the photosensitive drum 31 and a lens array, and exposes the surface of the photosensitive drum 31 to light to form an electrostatic latent image as a latent image.

[0027] In each of the image forming units 16Bk, 16Y, 16M, and 16C, the surface of the photosensitive drum 31 is uniformly charged by the charging roller 32 as it rotates, and is exposed by the LED head 22, forming an electrostatic latent image on the surface.

[0028] The toner supplied from the toner cartridge 29 to the toner storage unit 30 is supplied to the developing roller 33 by the supply roller 34, and the layer thickness is regulated by the developing blade Db to form a thin layer on the developing roller 33. At this time, the toner is negatively charged by friction between the supply roller 34 and the developing blade Db.

[0029] Then, the toner on the developing roller 33 is electrostatically attached to the electrostatic latent image, and a toner image is formed as a developer image on the photosensitive drum 31 .

[0030] A transfer unit u1 is detachably mounted on the device main body Bd below each of the image forming units 16Bk, 16Y, 16M, and 16C. The transfer unit u1 includes a drive roller r1 as a first roller, a driven roller r2 as a second roller, a transfer belt 17 as an endless belt member and conveyor belt stretched between the drive roller r1 and the driven roller r2, a transfer roller 21 as a transfer member rotatably disposed opposite the photosensitive drum 31 across an upper belt portion 17a of the transfer belt 17, and a second cleaning device C2 disposed opposite a lower belt portion 17b of the transfer belt 17. The second cleaning device C2 includes a cleaning blade b2 as a cleaning member that scrapes and removes toner adhering to the transfer belt 17.

[0031] A fixing device 18 is detachably mounted on the apparatus main body Bd downstream of the transfer unit u1 on the paper transport path Rt1. The fixing device 18 includes a rotatable heating roller 19 as a first fixing member having a halogen lamp (not shown) as a heating member inside, and a pressure roller 20 as a second fixing member rotatably mounted opposite the heating roller 19.

[0032] In the printer 10, when a transport motor (not shown) serving as a drive unit for transport is driven, the hopping roller 13 and the transport roller pair m1 are rotated, and paper P is fed from the paper feed cassette 11 to the paper transport path Rt1 and transported along the paper transport path Rt1.

[0033] Furthermore, when a belt motor (not shown) serving as a drive unit for driving the belt is driven, drive roller r1 is rotated in the direction of the arrow, causing transfer belt 17 to travel in the direction of arrow A. Paper P supplied to image forming units 16Bk, 16Y, 16M, and 16C is transported as transfer belt 17 travels, passes between each photosensitive drum 31 and each transfer roller 21, and is charged by each transfer roller 21 to a polarity opposite to that of the toner, and the toner images of black, yellow, magenta, and cyan formed on each photosensitive drum 31 in each image forming unit 16Bk, 16Y, 16M, and 16C are transferred onto paper P in succession, overlapping each other, to form a color toner image.

[0034] When a fixing motor (not shown) serving as a fixing drive unit is driven, the heating roller 19 and pressure roller 20 are rotated, and the paper P is sent to the fixing unit 18, where it is heated by the heating roller 19 and pressed by the pressure roller 20, the color toner image is fixed, and a color image is formed. The paper P is then discharged from the fixing unit 18 to the outside of the device body Bd by a pair of discharge rollers m2 serving as a discharge member, and is stacked in a stacker St2 formed at the top of the housing Cs.

[0035] Next, the LED head 22 will be described.

[0036] Fig. 3 is a perspective view of the LED head according to the embodiment of the present invention as seen diagonally from above, Fig. 4 is a perspective view of the LED head according to the embodiment of the present invention as seen diagonally from below, Fig. 5 is an exploded perspective view of the LED head according to the embodiment of the present invention, and Fig. 6 is a cross-sectional view taken along the line AA in Fig. 3. In Fig. 3, the positive X-axis direction is the forward direction in the transport direction of the paper P, the negative X-axis direction is the rearward direction in the transport direction of the paper P, the positive Y-axis direction is the leftward direction when viewing the LED head 22 from behind in the transport direction of the paper P, the negative Y-axis direction is the rightward direction when viewing the LED head 22 from behind in the transport direction of the paper P, the positive Z-axis direction is the upward direction in the printer 10, and the negative Z-axis direction is the downward direction in the printer 10.

[0037] In the figure, 22 is an LED head, 41 is a holder for the LED head 22, 43 is an eccentric cam, and 44 is an eccentric cam plate.

[0038] The holder 41 is formed by injection molding a resin material, for example, a liquid crystal polymer, and consists of a long box-shaped body extending in a direction perpendicular to the conveying direction of the paper P, and has a front wall pf, a back wall pr, a left side wall ps1 which is the first side wall, a right side wall ps2 which is the second side wall, a top wall pt, and a bottom wall pb.

[0039] The holder 41 has an optical system accommodating chamber Rm formed by penetrating it in the vertical direction, and the upper and lower ends of the optical system accommodating chamber Rm are open, with an upper opening Ht formed in the top wall pt and a lower opening Hb, which is slightly smaller than the upper opening Ht, formed in the bottom wall pb, facing the photosensitive drum 31 (Figure 2).

[0040] In order to fix the first substrate 52 to the holder 41, a plurality of through holes h1 are formed in the front wall pf and the rear wall pr, into which a substrate adhesive 74, which will be described later, is filled.

[0041] An elongated hole h2 serving as a first positioning hole is formed in the end of the bottom wall pb of the holder 41 on the left wall ps1 side, and a round hole h3 serving as a second positioning hole is formed in the end of the bottom wall pb on the right wall ps2 side, and the elongated hole h2 and round hole h3 are engaged with protrusions (not shown) formed on the unit body 28 to position the LED head 22 in the Y-axis direction. Cam fitting portions Q1 and Q2 are formed in the bottom wall pb closer to the center than the elongated hole h2 and round hole h3, and the cam fitting portions Q1 and Q2 are fitted with the eccentric cam 43 and held by the eccentric cam plate 44 to position the LED head 22 in the Z-axis direction.

[0042] Furthermore, at the ends of the top wall pt of the holder 41 on the left side wall ps1 side and the right side wall ps2 side, joints Q3 are formed for mechanically connecting the LED head 22 to the device body Bd using connecting members not shown.

[0043] At the bottom of the optical system housing chamber Rm, a cover film is adhered to the holder 41 using a specified jig to achieve high flatness, forming a cover 54.Using the cover 54 as a reference, a holding plate 51 made of an insulating film, for example, polyethylene terephthalate (PET), the first substrate 52, the optical system 53, etc. are stacked from the upper opening Ht to the lower opening Hb.

[0044] The optical system 53 is formed by stacking, from top to bottom, a first light-shielding member 61, a first lens array 62, a second light-shielding member 63, and a second lens array 64. The first lens array 62 has a plurality of microlenses 77 as first lens elements, and the second lens array 64 has a plurality of microlenses 78 as second lens elements, each arranged in two staggered rows. The first light-shielding member 61 forms a light-shielding member on the substrate side where the first substrate 52 is disposed, and the second light-shielding member 63 forms a light-shielding member on the drum side where the photosensitive drum 31 is disposed.

[0045] The holding plate 51 is attached to the upper opening Ht of the holder 41 so as to cover and protect the first substrate 52, with the second substrate 66 attached to the center, and the clearance between the first substrate 52 and the holder 41 is sealed by sealing silicone 67 as a sealing member, which prevents dust from entering the optical system housing chamber Rm from the outside and static electricity from being discharged to the first substrate 52.

[0046] The second board 66 is mounted with electronic components 71 such as ASIC that controls the first board 52, a connector (not shown) for electrically connecting to the first board 52, and a connector Cn1 for electrically connecting the second board 66 to a control unit (not shown) arranged in the device main body Bd.

[0047] The second substrate 66 is made of a glass epoxy substrate with copper foil attached to the base material, and uses FR4, which has high flame retardancy and low conductivity and is made by soaking glass fiber cloth in epoxy resin and subjecting it to a heat-curing process to form a plate.

[0048] On the first substrate 52, LEDs 69 as light emitting elements, electronic components 73 for controlling the driving (on / off) of each LED 69, a connector Cn2 for electrically connecting to the second substrate 66, and the like are mounted.

[0049] The first substrate 52 is a long member, and like the second substrate 66, the base material is FR4, which has high flame retardancy and low conductivity and is made by impregnating glass fiber cloth with epoxy resin and subjecting it to a heat-hardening treatment to form a plate, and is made from a glass epoxy substrate with copper foil attached to the base material.

[0050] The first substrate 52 is then adhered to the holder 41 by a substrate adhesive 74 filled through the through-hole h1 of the holder 41. This allows the first and second lens arrays 62 and 64 of the optical system 53, which have different linear expansion coefficients, to slide while maintaining accuracy in the height direction.

[0051] The cover 54 is attached to the lower opening Hb of the holder 41 with a cover adhesive 56 so as to cover and protect the second lens array 64, and the optical system 53 and first substrate 52 are stacked based on the cover 54, and the first substrate 52 is adhered to the holder 41 with the substrate adhesive 74.

[0052] The cover 54 is made of a transparent polyethylene terephthalate film and has a rectangular shape that is larger than the lower opening Hd and smaller than the inner peripheral surface of the holder 41 .

[0053] Next, the optical system 53 will be described.

[0054] The first light-shielding member 61 is an elongated member having a U-shaped cross-section consisting of side walls 81 and a bottom wall 82, and the bottom wall 82 has through holes h8, which are openings having a circular cross-section and a truncated cone shape, arranged in two staggered rows in accordance with the positions of each microlens 77, 78 formed in the first and second lens arrays 62, 64.

[0055] The first light blocking member 61 is disposed so that an optimum clearance is formed between each LED 69 and the first lens array 62 .

[0056] Although acrylonitrile-butadiene-styrene copolymer (ABS) can be used for the first light-shielding member 61, it is desirable to match the linear expansion coefficient as closely as possible to that of the first and second lens arrays 62 and 64, and therefore polycarbonate is used in this embodiment.

[0057] The first lens array 62 is an elongated member having a first optical axis and formed by arranging a plurality of microlenses 77 in two rows in a staggered pattern in the longitudinal direction, and the microlenses 77 focus the light from the LEDs 69 and emit the light.

[0058] The first lens array 62 can be made of acrylic resin, polycarbonate, epoxy resin, etc., but when the structure is long in the longitudinal direction as in this embodiment, it is necessary to stabilize the dimensions, so in this embodiment, cycloolefin polymer (COP), which has a low water absorption rate, is used.

[0059] The second light-shielding member 63 is a long member having a rectangular cross-sectional shape, and has through-holes h9 as openings having the shape of an inverted truncated cone arranged in two staggered rows and formed therethrough to correspond to each microlens 77, 78 formed in the first and second lens arrays 62, 64.

[0060] The second light-blocking member 63 is arranged so as to form an optimal clearance between the first and second lens arrays 62, 64, and blocks stray light generated by light rays emitted from the first lens array 62 from entering the second lens array 64.

[0061] The second lens array 64 has a second optical axis and an elongated shape formed by arranging a plurality of microlenses 78 in two rows in a staggered pattern in the longitudinal direction. That is, the second lens array 64 has substantially the same shape as the first lens array 62, rotated 180° about the Y axis. The microlenses 78 converge the light emitted from the microlenses 77 and also emit the light.

[0062] The first and second lens arrays 62 and 64 are stacked in the holder 41 so that the first and second optical axes are aligned, and the first lens array 62 forms an inverted, reduced image of the LED 69 between the first and second lens arrays 62 and 64, and the second lens array 64 forms an inverted, enlarged image of the inverted, reduced image of the LED 69. As a result, an erect, life-size image of the LED 69 is formed on the surface of the photosensitive drum 31 (FIG. 2).

[0063] The second lens array 64 can be made of acrylic resin, polycarbonate, epoxy resin, etc., but when the structure has a long longitudinal direction as in this embodiment, it is necessary to stabilize the dimensions, so in this embodiment, cycloolefin polymer (COP), which has a low water absorption rate, is used, as in the first lens array 62.

[0064] Next, the through hole h9 formed in the second light blocking member 63 will be described.

[0065] FIG. 1 is a conceptual diagram of a through hole formed in a second light-shielding member in an embodiment of the present invention.

[0066] In the figure, 63 denotes a second light blocking member, 64 denotes a second lens array, 78 denotes a microlens, and h9 denotes a through hole.

[0067] The through hole h9 includes a first opening Hu formed opposite the microlens 77 and a second opening Hd formed opposite the microlens 78. Between the first opening Hu and the second opening Hd, there are formed a first hole portion 85 having a truncated cone shape as a first opening portion, and a second hole portion 86 having a truncated cone shape concentric with the first hole portion 85 and formed integrally below the first hole portion 85. A wall surface w1 is formed on the inner circumferential surface of the first hole portion 85, and a wall surface w2 is formed on the inner circumferential surface of the second hole portion 86, extending between the first and second openings Hu and Hd, respectively.

[0068] When the diameter of the first opening Hu at the upper end of the first hole portion 85 is d1, the diameter of the lower end of the first hole portion 85 is d2, the diameter of the upper end of the second hole portion 86 is d3, and the diameter of the second opening Hd at the lower end of the second hole portion 86 is d4, the diameters d1 to d4 are expressed as follows: d1>d2 …(1) d2>d3 …(2) d3>d4 …(3) By satisfying the formula (2), a step is formed between the first and second hole portions 85 and 86.

[0069] Furthermore, when the distance between the upper end and the lower end of the first hole portion 85 is L1 and the distance between the upper end and the lower end of the second hole portion 86 is L2, the distances L1 and L2 are expressed as follows: L1>L2 …(4) The second hole 86 is formed in the vicinity of the second opening Hb.

[0070] When the inclination angle of the wall surface w1 of the first hole portion 85 with respect to the second optical axis of the second lens array 64 is γ1, the inclination angle γ1 is expressed as follows: γ1=(d1-d2) / (L1×2) When the inclination angle of the wall surface w2 of the second hole portion 86 with respect to the second optical axis of the second lens array 64 is γ2, the inclination angle γ2 is expressed as follows: γ2=(d3-d4) / (L2×2) and γ1 and γ2 are γ2>γ1 …(5) to be turned into

[0071] In this embodiment, d1=0.925 [mm] d2=0.855 [mm] d3=0.71 [mm] d4=0.66 [mm] L1=0.7 [mm] L2=0.1 [mm] The difference between the diameter d2 and the diameter d3 is Δd Δd=d2-d3 is set to 0.05 mm or more.

[0072] However, since the second light-shielding member 63 is located near the inverted reduced image formed by the first lens array 62, the reflected light generated on the inner surface of the through hole h9 of the second light-shielding member 63 is likely to become a strong stray light component.

[0073] However, in this embodiment, the structure of the through hole h9 satisfies the above formulas (1) to (5), and therefore it is possible to prevent the reflected light generated on the inner circumferential surface of the through hole h9 from becoming a stray light component.

[0074] That is, the formulas (1) to (3) are satisfied, d1>d2 d2>d3 d3>d4 Therefore, the inclination of the side surfaces of the truncated cones of the first and second hole portions 85 and 86 that form the through hole h9 is in the same direction. As a result, the first light-shielding member 63 can be easily molded integrally by injection molding.

[0075] Furthermore, equation (2) is satisfied, d2>d3 Therefore, a step portion 91 having an annular shape is formed between the first and second hole portions 85, 86, and the step portion 91 faces the second opening Hb, and forms an eave structure 92 as an annular wall portion that protrudes along the wall surface w2 and radially inward of the through hole h9.

[0076] Therefore, it is possible to cut off the reflected light generated on the wall surface w1 of the first hole portion 85, and it is possible to prevent the reflected light from becoming a stray light component.

[0077] Generally, as determined by Fresnel's equation, the reflectance increases as the angle of incidence with respect to an object increases. Therefore, in this embodiment, the difference Δd is set to 0.05 [mm], and even if the size of the step portion 91 is small, at approximately 0.025 [mm], reflected light can be sufficiently cut.

[0078] Furthermore, equation (4) is satisfied, L1>L2 Therefore, it is possible to cut the reflected light generated at w2 of the second hole portion 86, and it is possible to prevent the reflected light from becoming a stray light component.

[0079] Furthermore, equation (5) is satisfied, γ2>γ1 Therefore, the angle of incidence of the light incident on the wall surface w2 of the second hole portion 86 into the through hole h9 can be made smaller than the angle of incidence of the light on the wall surface w1 of the first hole portion 85. As a result, the reflected light generated on the wall surface w2 of the second hole portion 86 can be further cut, and the reflected light can be further prevented from becoming a stray light component.

[0080] As described above, in this embodiment, each through hole h9 has a first opening Hu formed opposite the microlens 77 and a second opening Hd formed opposite the microlens 78, and the diameter d4 of the second opening Hd is made smaller than the diameter d1 of the first opening Hu to form an eave structure 92, thereby cutting off stray light caused by reflected light generated on the wall surface w1 of the through hole h9.

[0081] Therefore, the quality of the LED head 22 can be improved.

[0082] In addition, since a through hole h8 similar to the through hole h9 of the second light-shielding member 63 is formed in the first light-shielding member 61, stray light is generated by the light emitted from the LED 69 being reflected on the wall surface of the through hole h8, but the stray light is cut by the eaves structure 92 while passing through the through hole h9.

[0083] Furthermore, in the present embodiment, in through hole h9, a step portion 91 is formed facing the second opening Hd, and the step portion 91 forms an overhang structure 92. However, in through hole h8, a step portion having an annular shape can also be formed facing an opening formed opposite the microlens 77, and the step portion can be used to form an overhang structure as an annular wall portion that protrudes radially inward from the through hole h8. Therefore, the overhang structure can cut stray light generated by light reflected on the wall surface of the through hole h8.

[0084] Although the present embodiment has been described with reference to the printer 10, the present invention can also be applied to image forming devices such as copying machines, facsimile machines, and multifunction machines.

[0085] The present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention. [Explanation of symbols]

[0086] 22 LED head 52 First board 62, 64 First and second lens arrays 63 Second light blocking member 69 LED 77, 78 Microlenses 92 Eaves structure d1, d4 diameter Hd, Hu First and second apertures h9 through hole w1, w2 walls

Claims

1. (a) a substrate having a plurality of light-emitting elements; (b) a first lens array in which a plurality of first lens elements that converge light from the light-emitting element and emit light are arranged; (c) a second lens array arranged opposite the first lens array, converging the light emitted from the first lens elements and including an array of second lens elements that emit light; (d) a light-blocking member disposed between the first and second lens arrays, the light-blocking member having a plurality of circular openings formed therethrough in correspondence with the first and second lens elements, (e) the plurality of openings include a first opening formed opposite the first lens element, a second opening formed opposite the second lens element, and a wall surface formed extending between the first and second openings; (f) An exposure apparatus characterized in that a wall portion is formed protruding from the wall surface, and the diameter of the second opening is made smaller than the diameter of the first opening.

2. 2. The exposure apparatus according to claim 1, wherein the opening comprises a first opening region formed on the first lens array side and a second opening region formed on the second lens array side adjacent to the first opening region.

3. 3. The exposure apparatus according to claim 2, wherein an inclination angle of the wall surface of the second opening portion relative to the optical axis of the second lens array is larger than an inclination angle of the wall surface of the first opening portion relative to the optical axis of the second lens array.

4. (a) the second opening region is formed adjacent to the second opening; 4. An exposure apparatus according to claim 2, wherein (b) the wall portion is formed facing the second opening.

5. 5. The exposure apparatus according to claim 2, wherein the first and second opening regions have a truncated cone shape.

6. 6. The exposure apparatus according to claim 1, wherein the wall portion is formed to protrude radially inward along a wall surface of the second opening portion.

7. (a) a substrate-side light-blocking member disposed between the substrate and the first lens element; (b) the light-blocking member on the substrate side has a plurality of openings formed therethrough in correspondence with the first lens elements; (c) The exposure apparatus according to any one of claims 1 to 6, wherein a wall portion is formed facing the opening formed opposite the first lens element in the opening portion.

8. An image forming apparatus comprising the exposure device according to any one of claims 1 to 7.

9. (a) a first lens array in which a plurality of first lens elements that converge light and emit light are arranged; (b) a second lens array arranged opposite the first lens array, converging the light emitted from the first lens elements and including an array of second lens elements that emit light; (c) a light-blocking member disposed between the first and second lens arrays, the light-blocking member having a plurality of circular openings formed therethrough in correspondence with the first and second lens elements, (d) the plurality of openings include a first opening formed opposite the first lens element, a second opening formed opposite the second lens element, and a wall surface formed extending between the first and second openings; (e) A lens array unit, wherein a wall portion is formed protruding from the wall surface, and the diameter of the second opening is smaller than the diameter of the first opening.

Images