Exposure device and image forming device

Abstract

To provide an exposure device capable of maintaining appropriate image quality.SOLUTION: An image forming device includes a panel member 12a facing a photoreceptor and having a plurality of light emitting elements 41. The panel member 12a has a plurality of element groups in which a plurality of light emitting devices 41 are arranged in a main scanning direction S along the rotation axis of the photoreceptor. The element group includes a normal order arrangement in which the plurality of light emitting devices 41 are arranged so that the positions in the sub-scanning direction H orthogonal to the main scanning direction S are shifted from one end side to the other end side toward one side in the main scanning direction S, and a reverse order arrangement in which the plurality of light emitting devices 41 are arranged so that the positions in the sub-scanning direction H are shifted from the other end side to the one end side toward one side in the main scanning direction S.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an exposure device and an image forming apparatus that include a panel member having a plurality of light-emitting elements. [Background technology]

[0002] Conventionally, electrophotographic image forming apparatuses have been widely used, which form an electrostatic latent image on a photosensitive member using a laser beam or the like, and then develop, transfer, and fix the electrostatic latent image to form an image on paper. In recent years, linear light sources, in which point light sources such as light-emitting elements are arranged in a line, have been used as the light source for exposing the photosensitive member. Also, methods have been proposed in which a plurality of light-emitting elements are arranged not only in the main scanning direction but also in the sub-scanning direction to increase the amount of exposure and the pixel density (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-103240 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-203021 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-25580 Summary of the Invention [Problem to be solved by the invention]

[0004] A conventional image recording device for silver halide photographic light-sensitive materials has a recording head in which a plurality of light-emitting elements are arranged in one or more dotted lines, and after the device is turned on, a preparatory light emission is performed to cause the light-emitting elements of the recording head to emit light before starting image recording.

[0005] Furthermore, a conventional image forming apparatus includes a light emitting array in which light emitting points are arranged in the main scanning direction, a photosensitive member exposed by the light emitting array, an image forming unit that forms an image, and a light emitting control device that controls the light emitting array. The light emitting control device performs a process of determining each light emitting point group so that the boundaries of the light emitting point groups to which correction values ​​for the sub-scanning direction are assigned do not overlap with the boundaries of the light emitting point groups to which correction values ​​for light intensity correction are assigned in the main scanning direction, and a process of correcting the sub-scanning position and the light intensity with the light emitting points of each light emitting point group as one unit.

[0006] In addition, conventional image forming devices have multiple light-emitting element lines in the sub-scanning direction, each line having multiple organic EL elements arranged in the main scanning direction of an image carrier, an image writing means in which the organic EL elements are arranged two-dimensionally, and a control unit for the organic EL elements, and the control unit lights up at least one organic EL element at least once during one main scanning direction to form a latent image of the same dot by multiple exposure.

[0007] However, in order to achieve higher definition and lower power consumption, it is sometimes difficult to arrange light-emitting elements in a line or in a matrix, and they are sometimes arranged with a periodic offset in the sub-scanning direction. When arranged in this manner, when light-emitting elements that are far apart in the sub-scanning direction expose adjacent pixels, a phenomenon known as reciprocity failure occurs, resulting in a problem of higher density than expected.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an exposure device and an image forming apparatus that can suppress variations in exposure time differences and reduce density unevenness. [Means for solving the problem]

[0009] The exposure device according to the present disclosure is an exposure device comprising a panel member facing a photosensitive body and having a plurality of light-emitting elements, wherein the panel member has a plurality of element groups in which the plurality of light-emitting elements are arranged in a main scanning direction along the rotation axis of the photosensitive body, and the element groups include a forward permutation arrangement in which the plurality of light-emitting elements are arranged so that their positions in a sub-scanning direction perpendicular to the main scanning direction shift from one end side to the other end side as they move in one direction of the main scanning direction, and a reverse permutation arrangement in which the plurality of light-emitting elements are arranged so that their positions in the sub-scanning direction shift from the other end side to one end side as they move in one direction of the main scanning direction.

[0010] In the exposure apparatus according to the present disclosure, the element group may be configured to include two or more of either the forward permutation arrangement or the reverse permutation arrangement.

[0011] In the exposure device according to the present disclosure, the plurality of light-emitting elements may be arranged in m rows with a spacing of L in the sub-scanning direction, and the distance between adjacent light-emitting elements in the main scanning direction may be less than (m-1)×L in the sub-scanning direction.

[0012] In the exposure apparatus according to the present disclosure, the plurality of element groups may have a configuration in which the arrangement of the plurality of light-emitting elements is common.

[0013] The image forming apparatus according to the present disclosure is characterized by including the exposure device according to the present disclosure. [Effects of the Invention]

[0014] According to the present disclosure, by arranging a plurality of light-emitting elements in one direction, then folding back midway and arranging them in the opposite direction, it is possible to avoid the light-emitting elements being spaced apart at the boundary of the period when the plurality of light-emitting elements are arranged periodically. Furthermore, by making the distance between adjacent light-emitting elements in the sub-scanning direction as uniform as possible, it is possible to suppress variations in exposure time differences and reduce density unevenness. [Brief explanation of the drawings]

[0015] [Figure 1]1 is a schematic cross-sectional view showing an image forming apparatus according to a first embodiment of the present disclosure. [Figure 2] 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic plan view showing a panel member in a reference example. [Figure 4] FIG. 10 is a characteristic diagram showing the relationship between exposure time difference and density. [Figure 5] FIG. 2 is a schematic plan view showing a panel member according to the first embodiment of the present disclosure. [Figure 6] FIG. 10 is a schematic plan view showing a panel member according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] (First embodiment) Hereinafter, an image forming apparatus according to a first embodiment of the present disclosure will be described with reference to the drawings.

[0017] FIG. 1 is a schematic cross-sectional view showing an image forming apparatus according to a first embodiment of the present disclosure.

[0018] The image forming device 100 is a multifunction device having a copy function, a scanner function, a facsimile function, and a printer function, and transmits an image of a document read by the image reading device 130 to an external device, and forms an image of a document read by the image reading device 130 or an image received from an external device in color or monochrome on a recording medium such as paper.

[0019] An original transport device 110 that is supported so as to be able to open and close freely is provided above the image reading device 130. The original transport device 110 transports one or more originals one by one. The image reading device 130 scans a scanning optical system 130b to read an original placed on an original placement table 130a, or reads an original transported by the original transport device 110 to generate image data.

[0020] The image forming apparatus 100 is provided with a fixing device 1, a developing device 2, a photosensitive drum 3 (an example of a photosensitive body), a drum cleaning device 4, a charger 5, an intermediate transfer belt device 7, a secondary transfer device 11, an exposure device 12, and a paper feed section 18.

[0021] Image forming apparatus 100 handles image data corresponding to color images using black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (e.g., black). Image forming apparatus 100 is provided with four developing devices 2, four photosensitive drums 3, four drum cleaning devices 4, and four chargers 5 for forming four types of toner images, and four image stations Pa, Pb, Pc, and Pd are configured corresponding to black, cyan, magenta, and yellow, respectively.

[0022] The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential. The exposure device 12 has a panel member 12a facing the surface of the photosensitive drum 3, and exposes the surface of the photosensitive drum 3 to light to form an electrostatic latent image. The development device 2 develops the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image on the surface of the photosensitive drum 3. The drum cleaning device 4 removes and collects residual toner on the surface of the photosensitive drum 3. Through the series of operations described above, a toner image of each color is formed on the surface of each photosensitive drum 3. The panel member 12a will be described in detail later with reference to FIG. 3.

[0023] The intermediate transfer belt device 7 includes an intermediate transfer roller 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 so as to form four types of toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photosensitive drum 3 onto the intermediate transfer belt 71, which moves around in a circular motion.

[0024] The intermediate transfer belt 71 is stretched over an intermediate transfer drive roller 72 and an intermediate transfer driven roller 73. In the image forming apparatus 100, the toner images of each color formed on the surface of each photosensitive drum 3 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 71. The cleaning device 9 removes and collects waste toner remaining on the surface of the intermediate transfer belt 71 without being transferred to paper.

[0025] The secondary transfer device 11 sandwiches and transports a sheet of paper transported through the paper transport path 21 in the transfer nip portion TN between the secondary transfer roller 11a and the intermediate transfer belt 71. When the sheet of paper passes through the transfer nip portion TN, the toner image on the surface of the intermediate transfer belt 71 is transferred onto the sheet of paper, and the sheet of paper is transported to the fixing device 1.

[0026] The fixing device 1 includes a fixing belt 31 that rotates around an axis and a pressure roller 32. The fixing device 1 sandwiches a sheet of paper onto which a toner image has been transferred in a nip portion N between the fixing belt 31 and the pressure roller 32, and applies heat and pressure to fix the toner image to the sheet. Although not shown in FIG. 1, the fixing device 1 may include components other than the fixing belt 31 and the pressure roller 32.

[0027] The paper feed unit 18 includes a paper feed cassette that holds recording media (paper) used for image formation, and is provided below the exposure device 12. The paper is pulled out of the paper feed unit 18 by a pickup roller 16 and transported to a paper transport path 21. The paper transported to the paper transport path 21 passes through the secondary transfer device 11 and the fixing device 1, and is then discharged to a paper output tray 19 by a discharge roller 17.

[0028] Conveyance rollers 13, registration rollers 14, and discharge rollers 17 are arranged on paper conveyance path 21. Conveyance rollers 13 facilitate the conveyance of paper. Registration rollers 14 convey paper at a speed equal to the process speed at which an image is formed on the paper. Registration rollers 14 are provided between paper feed unit 18 and secondary transfer device 11, and adjust the timing of paper conveyance so that the toner image is transferred to the paper by secondary transfer device 11. For example, registration rollers 14 wait (temporarily stop) while clamping paper conveyed from paper feed unit 18, and then start conveying the paper at a constant speed in synchronization with secondary transfer device 11.

[0029] When an image is to be formed on the back side of the paper in addition to the front side, the conveying direction of the paper is changed by discharge rollers 17, and the paper is conveyed to reversing conveying path 22. In reversing conveying path 22, the paper is guided up to registration rollers 14 in a reversed state by reversing conveying rollers 15. Image forming apparatus 100 forms an image on the back side of the paper guided to registration rollers 14 in the same manner as on the front side, and discharges the paper to discharge tray 19.

[0030] Fig. 2 is a schematic configuration diagram showing an image forming apparatus according to the first embodiment of the present disclosure. Note that Fig. 2 shows only a portion of the image forming apparatus 100, and other members not shown in Fig. 2 may be included as appropriate.

[0031] The panel member 12a has a plurality of light-emitting elements 41. The light-emitting elements 41 are, for example, organic light-emitting diodes (OLEDs), LEDs, etc. The control unit 50 is a CPU mounted in the image forming apparatus 100, and controls the operation of the image forming apparatus 100.

[0032] FIG. 3 is a schematic plan view showing a panel member in a reference example.

[0033] The exposure device 12 is provided with four panel members 12a so as to face the four photosensitive drums 3, respectively. Note that the exposure device 12 may be provided independently for each photosensitive drum 3, as long as a panel member 12a is provided corresponding to each of the four photosensitive drums 3. The four panel members 12a have substantially the same configuration, and therefore, in FIG. 3, one panel member 12a is extracted and schematically shown.

[0034] In the image forming apparatus 100, the axial direction of the rotation axis of the photosensitive drum 3 is parallel to the width direction of the paper on which an image is formed, and the photosensitive drum 3 is configured to rotate around the axis of the rotation axis. The panel member 12a is a rectangular flat plate, and its longitudinal direction (main scanning direction S) corresponds to the axial direction, and its lateral direction (sub-scanning direction H) corresponds to the rotation direction of the photosensitive drum 3.

[0035] The panel member 12a in the reference example has a plurality of element groups (first element group Gr1 and second element group Gr2) in which a plurality of light-emitting elements 41 are arranged in the main scanning direction S. FIG. 3 shows the panel member 12a having the first element group Gr1 and the second element group Gr2 each composed of eight light-emitting elements 41, but this is not limited thereto, and the number of light-emitting elements 41 constituting the element groups and the number of element groups provided on the panel member 12a may be changed as appropriate. In the following, in order to distinguish the plurality of light-emitting elements 41, the light-emitting elements 41 may be referred to by being numbered d1, d2, . . . , d16 in order from one end (the left end in FIG. 3) to the other end (the right end in FIG. 3) in the main scanning direction S. That is, the first element group Gr1 is composed of light-emitting elements 41 d1 to d8, and the second element group Gr2 is composed of light-emitting elements 41 d9 to d16.

[0036] In the element group, adjacent light-emitting elements 41 in the main scanning direction S are arranged such that their positions in the sub-scanning direction H are shifted from one end side (the upper end side in FIG. 3) to the other end side (the lower end side in FIG. 3) as they move in one direction in the main scanning direction S. The dashed lines H1 to H8 (first line to eighth line) shown in FIG. 3 are parallel to the main scanning direction S, lined up in the sub-scanning direction H at regular intervals, and indicate their positions in the sub-scanning direction H. In other words, the light-emitting elements 41 arranged on the same line are positioned overlapping each other in the sub-scanning direction H.

[0037] In the panel member 12a shown in Fig. 3, the light emitting element 41 at d1 is arranged on a first line (H1) located at the uppermost end in Fig. 3, and the light emitting element 41 at d2 is arranged on a second line (H2) shifted downward from the first line. The light emitting elements 41 from d3 onwards are also arranged shifted downward in the same manner, and the light emitting element 41 at d8 is arranged on an eighth line (H8) located at the lowermost end in Fig. 3.

[0038] The second element group Gr2 repeats the same arrangement as the first element group Gr1, with the light emitting element 41 at d9 being arranged on the first line (H1), and the light emitting elements 41 at d10 and onwards being arranged in order shifted downward, with the light emitting element 41 at d16 being arranged on the eighth line (H8).

[0039] As described above, the distance between adjacent light-emitting elements 41 in the same element group, for example, the light-emitting element 41 at d2 and the light-emitting element 41 at d3, is one line (1 line difference: 1Ln) in the sub-scanning direction H. However, at the boundary between element groups, the distance between adjacent light-emitting elements 41 at d8 and the light-emitting element 41 at d9, for example, is seven lines (7 line difference: 7Ln) in the sub-scanning direction H.

[0040] The exposure device 12 exposes the light-emitting elements 41 in order from the light-emitting element 41 located upstream in the rotation direction of the photosensitive drum 3, and controls the timing at which the light-emitting elements 41 expose in accordance with the rotation of the photosensitive drum 3. Specifically, in the configuration shown in Fig. 3, the light-emitting elements 41 on the first line (H1), i.e., the light-emitting elements 41 at d1 and the light-emitting elements 41 at d9, are located furthest upstream in the rotation direction of the photosensitive drum 3 and are exposed first. Furthermore, the light-emitting elements 41 on the eighth line (H8), i.e., the light-emitting elements 41 at d8 and the light-emitting elements 41 at d16, are located furthest downstream in the rotation direction of the photosensitive drum 3 and are exposed last.

[0041] Here, if we focus on the light-emitting element 41 d9 arranged at one end in the sub-scanning direction H and the light-emitting element 41 d8 arranged at the other end in the sub-scanning direction H, although they are arranged adjacent to each other in the main scanning direction S, they are arranged farthest apart among the multiple light-emitting elements 41 in the sub-scanning direction H, and there is a large time difference in the timing of exposure between them. If the difference in the timing of exposure (exposure time difference) between adjacent pixels is large, it will affect the density, which will be explained with reference to FIG. 4.

[0042] FIG. 4 is a characteristic diagram showing the relationship between the exposure time difference and the density.

[0043] In FIG. 4, the horizontal axis represents the exposure time difference between adjacent pixels, and the vertical axis represents pixel density. As described above, when the exposure time difference between adjacent pixels is large, the pixel density may become high due to a phenomenon known as reciprocity failure. In FIG. 4, point P1 corresponds to the exposure time difference for a one-line difference of 1Ln, and point P2 corresponds to the exposure time difference for a seven-line difference of 7Ln, with point P2 having a higher density than point P1. As such, even if the same settings such as exposure amount are used to achieve the same density, the intended density may not be obtained depending on the arrangement of the light-emitting elements 41.

[0044] In contrast to this, in the present embodiment, an appropriate density is adjusted by adjusting the arrangement of light-emitting elements 41. Next, the arrangement of light-emitting elements 41 on panel member 12a in the present embodiment will be described with reference to FIG.

[0045] FIG. 5 is a schematic plan view showing a panel member according to the first embodiment of the present disclosure.

[0046] 5, similar to FIG. 3, one panel member 12a is extracted and schematically shown. In the present embodiment, the panel member 12a also has two element groups (a first element group Gr1 and a second element group Gr2) in which a plurality of light-emitting elements 41 are arranged in the main scanning direction S. The first element group Gr1 is made up of light-emitting elements 41 d1 to d8, and the second element group Gr2 is made up of light-emitting elements 41 d9 to d16.

[0047] In the panel member 12a shown in Figure 5, the light-emitting element 41 of d1 is arranged on the first line (H1), the light-emitting element 41 of d2 is arranged on the third line (H3) shifted downward from the first line, the light-emitting element 41 of d3 is arranged on the fifth line (H5) shifted downward from the third line, the light-emitting element 41 of d4 is arranged on the seventh line (H7) shifted downward from the fifth line, and the light-emitting element 41 of d5 is arranged on the eighth line (H8) shifted downward from the seventh line.

[0048] In other words, the light-emitting elements 41 d1 to d5 are arranged in a normal sequence such that their positions in the sub-scanning direction H are shifted from one end (the upper end in FIG. 5) to the other end (the lower end in FIG. 5) as they move toward one side of the main scanning direction S (the right end in FIG. 5).

[0049] Next, the light emitting element 41 at d6 is arranged on the sixth line (H6) shifted upward from the eighth line, the light emitting element 41 at d7 is arranged on the fourth line (H4) shifted upward from the sixth line, and the light emitting element 41 at d8 is arranged on the second line (H2) shifted upward from the fourth line. The second element group Gr2 has the same arrangement of the light emitting elements 41 as the first element group Gr1, and the light emitting elements 41 at d9 to d16 are arranged in the same way as the light emitting elements 41 at d1 to d8.

[0050] That is, the light emitting elements 41 d5 to d9 are arranged in reverse order such that their positions in the sub-scanning direction H are shifted from the other end side to one end side as they move toward one side in the main scanning direction S.

[0051] In this embodiment, when attention is paid to the distance between adjacent light-emitting elements 41 in the sub-scanning direction H, for example, the distance between the light-emitting element 41 at d4 and the light-emitting element 41 at d5 in the sub-scanning direction H is the distance of one line (1 line difference 1Ln), which is the smallest distance between them. Also, the distance between the light-emitting element 41 at d5 and the light-emitting element 41 at d6 in the sub-scanning direction H is the distance of two lines (2 line difference 2Ln), which is the largest distance between them.

[0052] In the reference example shown in FIG. 3 , the distance between the light-emitting elements 41 included cases where the distance was 1Ln (one line difference) and cases where the distance was 7Ln (seven lines difference), resulting in large variations in the exposure time difference. In contrast, in the present embodiment, the narrowest spacing is 1Ln (one line difference) and the widest spacing is 2Ln (two lines difference), resulting in small variations in the exposure time difference. By arranging multiple light-emitting elements 41 in one direction, then turning back midway and arranging them in the opposite direction, it is possible to prevent the light-emitting elements 41 from being spaced apart at the boundary of the period when the multiple light-emitting elements 41 are arranged periodically. Furthermore, by making the distance between adjacent light-emitting elements 41 in the sub-scanning direction H as uniform as possible, it is possible to suppress variations in the exposure time difference and reduce density unevenness. Furthermore, by periodically repeating a common arrangement of the light-emitting elements 41, the number of light-emitting elements 41 can be easily increased, improving design flexibility.

[0053] In the panel member 12a, the number of columns in which the light-emitting elements 41 are arranged may be changed as appropriate. For example, when m columns of light-emitting elements 41 are arranged with an interval of L in the sub-scanning direction H, the light-emitting elements 41 adjacent to each other in the main scanning direction S may be arranged such that the distance in the sub-scanning direction H between the light-emitting elements 41 is less than (m-1)×L. As a result, it is possible to avoid arranging the light-emitting elements 41 adjacent to each other in the main scanning direction S in columns at both ends, and to avoid arranging the light-emitting elements 41 with the greatest distance between them.

[0054] (Second embodiment) Next, an image forming apparatus according to a second embodiment of the present disclosure will be described with reference to the drawings. In the second embodiment, the arrangement of the light-emitting elements 41 is different from that of the first embodiment. Note that the second embodiment has a configuration substantially similar to that of the first embodiment shown in Figures 1 to 5, and therefore a description thereof will be omitted, and only the differences will be described.

[0055] FIG. 6 is a schematic plan view showing a panel member according to the second embodiment of the present disclosure.

[0056] 6, similar to FIG. 5, one panel member 12a is extracted and schematically shown. In the present embodiment, the panel member 12a also has two element groups (a first element group Gr1 and a second element group Gr2) in which a plurality of light-emitting elements 41 are arranged in the main scanning direction S. The first element group Gr1 is made up of light-emitting elements 41 d1 to d8, and the second element group Gr2 is made up of light-emitting elements 41 d9 to d16.

[0057] 6, the light-emitting element 41 of d1 is arranged on a first line, the light-emitting element 41 of d2 is arranged on a fourth line shifted downward from the first line, and the light-emitting element 41 of d3 is arranged on an eighth line shifted downward from the fourth line. In other words, the light-emitting elements 41 of d1 to d3 are arranged in a normal order such that their positions in the sub-scanning direction H are shifted from one end side (the upper end side in FIG. 6) to the other end side (the lower end side in FIG. 6) as they move toward one side in the main scanning direction S (the right end side in FIG. 6).

[0058] Next, the light-emitting element 41 at d4 is arranged on the 5th line which is shifted upward from the 8th line, and the light-emitting element 41 at d5 is arranged on the 2nd line which is shifted upward from the 5th line. In other words, the light-emitting elements 41 at d3 to d5 are arranged in a reverse order such that their positions in the sub-scanning direction H are shifted from the other end to one end as they move toward one side of the main scanning direction S.

[0059] The light emitting element 41 at d6 is arranged on a sixth line shifted downward from the second line, the light emitting element 41 at d7 is arranged on a third line shifted upward from the sixth line, and the light emitting element 41 at d8 is arranged on the sixth line shifted downward from the third line. The second element group Gr2 has the same arrangement of the light emitting elements 41 as the first element group Gr1, and the light emitting elements 41 at d9 to d16 are arranged in the same way as the light emitting elements 41 at d1 to d8.

[0060] Focusing on the light-emitting elements 41 of d5 to d9, the light-emitting elements 41 of d5 and d6 are arranged in a forward permutation, the light-emitting elements 41 of d6 and d7 are arranged in a reverse permutation, the light-emitting elements 41 of d7 and d8 are arranged in a forward permutation, and the light-emitting elements 41 of d8 and d9 are arranged in a reverse permutation.

[0061] In this embodiment, when attention is paid to the distance between adjacent light-emitting elements 41 in the sub-scanning direction H, for example, the distance between the light-emitting element 41 at d1 and the light-emitting element 41 at d2 in the sub-scanning direction H is the distance of one line (3Ln, a difference of three lines), which is the smallest distance between them. Also, the distance between the light-emitting element 41 at d5 and the light-emitting element 41 at d6 in the sub-scanning direction H is the distance of five lines (5Ln, a difference of five lines), which is the largest distance between them.

[0062] In this embodiment, one element group is configured to include two or more of either the forward permutation arrangement or the reverse permutation arrangement, with the shortest spacing being 3Ln with a difference of three lines and the longest spacing being 5Ln with a difference of five lines, and by increasing the number of times of folding, the distance between the light-emitting elements 41 is increased while the difference is made smaller. As a result, by efficiently utilizing the increase in density due to reciprocity failure, the overall density is increased and the light intensity of the light-emitting elements 41 is reduced, thereby achieving low power consumption.

[0063] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0064] 3 Photoconductor drum (an example of a photoconductor) 12 Exposure equipment 12a Panel member 41 Light-emitting element 50 control section 100 Image forming device S Main scanning direction H Sub-scanning direction

Claims

1. An exposure device including a panel member facing a photosensitive member and having a plurality of light-emitting elements, the panel member has a plurality of element groups in which the plurality of light-emitting elements are arranged in a main scanning direction along the rotation axis of the photosensitive member, The element group includes: a forward arrangement in which the plurality of light-emitting elements are arranged so that their positions in a sub-scanning direction orthogonal to the main scanning direction are shifted from one end side to the other end side as they move toward one side of the main scanning direction; a reverse permutation arrangement in which the plurality of light-emitting elements are arranged so that their positions in the sub-scanning direction are shifted from one end side to the other end side as they move in one direction in the main scanning direction. An exposure apparatus characterized by:

2. 2. The exposure apparatus according to claim 1, The element group includes two or more of either the forward permutation arrangement or the reverse permutation arrangement. An exposure apparatus characterized by:

3. 2. The exposure apparatus according to claim 1, The plurality of light-emitting elements are arranged in m rows at intervals of L in the sub-scanning direction, The distance between the light-emitting elements adjacent to each other in the main scanning direction is less than (m-1) x L in the sub-scanning direction. An exposure apparatus characterized by:

4. 2. The exposure apparatus according to claim 1, The plurality of element groups have a common arrangement of the plurality of light-emitting elements. An exposure apparatus characterized by:

5. An image forming apparatus comprising the exposure device according to claim 1.

Images