Light emitting component, light writing device, and image forming apparatus

Abstract

The present application provides a light emitting component, a light writing device and an image forming apparatus, the light emitting component comprising: a first light emitting element column comprising light emitting elements arranged in a main scanning direction; and a second light emitting element column comprising light emitting elements arranged in the main scanning direction, the second light emitting element column being arranged in the main scanning direction so as to be offset in a sub-scanning direction relative to the first light emitting element column and each light emitting element in the second light emitting element column being located between respective light emitting elements in the first light emitting element column, the light emitting component being configured so that a region in which each light emitting element of the first light emitting element column emits light, i.e. a light emitting point region, and a region in which each light emitting element of the second light emitting element column emits light, i.e. a light emitting point region, overlap in the main scanning direction.

Description

Technical Field

[0001] The present invention relates to a light-emitting component, a light writing device using the light-emitting component, and an image forming device. Background Technology

[0002] Previously, most image forming devices used a method of writing light-based images onto a photoreceptor or dielectric using a light writing device.

[0003] As such optical writing devices, for example, there is the optical writing device described in Patent Document 1.

[0004] In Patent Document 1, an array of light-emitting elements is provided as a light-emitting component used in an optical writing device. The array of light-emitting elements is configured such that the light-emitting points of the light-emitting elements are not arranged in a single column in the main scanning direction, but are arranged in two staggered columns.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 5862404 (Detailed Embodiments, Figure 4 ) Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The technical problem to be solved by the present invention is to provide a light-emitting component, a light writing device using the light-emitting component, and an image forming apparatus, which can ensure the light-emitting area of ​​light-emitting elements arranged in the main scanning direction and can narrow the arrangement interval of adjacent light-emitting points of light-emitting elements arranged in the main scanning direction.

[0010] Methods for solving problems

[0011] [1] According to one aspect of the present disclosure, a light-emitting component is provided, comprising: a first light-emitting element column consisting of light-emitting elements arranged in a main scanning direction; and a second light-emitting element column consisting of light-emitting elements arranged in a main scanning direction, wherein the second light-emitting element column is arranged in the main scanning direction such that it is offset relative to the first light-emitting element column in a sub-scanning direction and each light-emitting element in the second light-emitting element column is located between each light-emitting element in the first light-emitting element column, wherein the light-emitting component configures the light-emitting areas, i.e., light-emitting point areas, of each light-emitting element in the first light-emitting element column and the light-emitting areas, i.e., light-emitting point areas, of each light-emitting element in the second light-emitting element column to overlap in the main scanning direction.

[0012] [2] According to one aspect of the present disclosure, a light-emitting component is provided, comprising: a first light-emitting element column consisting of light-emitting elements arranged in a main scanning direction; and a second light-emitting element column consisting of light-emitting elements arranged in a main scanning direction, wherein the second light-emitting element column is arranged in the main scanning direction such that the second light-emitting element column is offset relative to the first light-emitting element column in a sub-scanning direction and each light-emitting element in the second light-emitting element column is located between each light-emitting element in the first light-emitting element column, wherein the light-emitting component configures a region of light-emitting beam emitted by each light-emitting element of the first light-emitting element column and directed toward an object and a region of light-emitting beam emitted by each light-emitting element of the second light-emitting element column and directed toward an object such that there is no gap in the main scanning direction.

[0013] [3] In the light-emitting component according to [1] or [2], the arrangement spacing of the light-emitting points of each light-emitting element in the first light-emitting element column and the light-emitting points of each light-emitting element in the second light-emitting element column in the main scanning direction is less than 1 / 2 of the arrangement spacing between the light-emitting points of each light-emitting element in the main scanning direction between the first light-emitting element column and the second light-emitting element column.

[0014] [4] In the light-emitting component according to [3], the overlap range of the light-emitting point regions of adjacent light-emitting elements between the first light-emitting element column and the second light-emitting element column in the main scanning direction may be between 30% and 70%.

[0015] [5] In the light-emitting component according to [3], the overlap range of the light-emitting beam regions of adjacent light-emitting elements between the first light-emitting element column and the second light-emitting element column in the main scanning direction may be between 0% and 10%.

[0016] [6] In the light-emitting component according to [3], the arrangement spacing between the light-emitting points of each light-emitting element in the first light-emitting element column and the light-emitting points of each light-emitting element in the second light-emitting element column in the sub-scanning direction is an integer N times the imaging line spacing.

[0017] [7] According to one aspect of the present disclosure, an optical writing apparatus is provided, comprising a light-emitting component according to any one of [1] to [6], and an imaging unit for imaging light emitted from each light-emitting element of the light-emitting component onto an image holding unit capable of holding a light-based image, the optical writing apparatus writing the light-based image into the image holding unit.

[0018] [8] In the optical writing device according to [7], the imaging unit may also be formed by arranging a refractive index distribution lens with a diameter larger than the difference between the sub-scanning directions of the first light-emitting element column and the second light-emitting element column in the main scanning direction.

[0019] [9] In the optical writing device according to [8], the emitted light from the first light-emitting element column and the second light-emitting element column may be incident on different positions relative to the refractive index distribution lens in the sub-scanning direction.

[0020]

[10] In the optical writing device according to [9], there may also be a plurality of light-emitting element chips including the first light-emitting element column and the second light-emitting element column, the plurality of light-emitting element chips being offset in the sub-scanning direction and the main scanning direction, the imaging unit being formed by arranging the refractive index distribution lens adjacent to each other in the main scanning direction in multiple columns, light from each light-emitting element of the same light-emitting element chip being incident on the refractive index distribution lens arranged in the same column in the main scanning direction, and light from each light-emitting element of adjacent light-emitting element chips being incident on refractive index distribution lenses in different columns.

[0021]

[11] According to one aspect of the present disclosure, an image forming apparatus is provided, comprising: a light writing device according to any one of [7] to

[10] ; and an image holding unit disposed opposite to the light writing device and holding a light-based image written by the light writing device.

[0022]

[12] In the image forming apparatus according to

[11] , the light writing device may also configure the imaging beam region corresponding to the light emission point adjacent in the main scanning direction to overlap when writing a linear image along the main scanning direction into the image holding unit using light emitted from each of the light emission elements of the first light emission element column and the second light emission element column.

[0023] Invention Effects

[0024] According to [1] or [2], it is possible to ensure the light-emitting area of ​​the light-emitting elements arranged in the main scanning direction, and to ensure the arrangement interval of the adjacent light-emitting points of the light-emitting elements arranged in the main scanning direction.

[0025] According to [3], the actual arrangement spacing of the light-emitting points of the light-emitting component can be narrowed to less than 1 / 2 of the arrangement spacing in the main scanning direction between the light-emitting points of each light-emitting element in the first light-emitting element column and the second light-emitting element column.

[0026] According to [4], by appropriately selecting the overlap of the light-emitting point regions, it is possible to improve the resolution while maintaining the light output.

[0027] According to [5], by appropriately selecting the overlapping regions of the emitting beams, it is possible to improve the resolution while maintaining the light output.

[0028] According to [6], the offset of the first and second light-emitting element columns along the sub-scanning direction can be appropriately selected.

[0029] According to [7], an optical writing device can be provided, which includes a light-emitting component that can ensure the light-emitting area of ​​light-emitting elements arranged in the main scanning direction and can narrow the arrangement interval of adjacent light-emitting points of light-emitting elements arranged in the main scanning direction.

[0030] According to [8], even if the imaging unit has tilt or configuration tolerance, it is possible to mitigate the deviation of the light path from each light-emitting element in the first and second light-emitting element columns.

[0031] According to [9], compared with the case where the light from the first and second light-emitting elements is incident at the same position on the refractive index distribution lens, the effect caused by the deviation of the incident position can be suppressed.

[0032] According to

[10] , compared to the case where multiple refractive index distribution lenses are not assigned to the optical paths from each column of light-emitting element chips in an offset configuration, the effects caused by the deviation of the refractive index distribution lenses per column can be suppressed.

[0033] According to

[11] , an image forming apparatus having an optical writing device can be provided, the optical writing device including a light-emitting component, the light-emitting component being able to ensure the light-emitting area of ​​light-emitting elements arranged in the main scanning direction, and being able to narrow the arrangement interval of adjacent light-emitting points of light-emitting elements arranged in the main scanning direction.

[0034] According to

[12] , compared with the method of configuring the imaging beam diameters corresponding to adjacent light-emitting points in the main scanning direction to not overlap, it is possible to suppress the influence caused by the deviation of the light-emitting characteristics of each light-emitting element. Attached Figure Description

[0035] Figure 1 (a) is an explanatory diagram showing an outline of an embodiment of the image forming apparatus to which the present invention is applied; (b) is an explanatory diagram showing a structural example of the light-emitting component used in (a); and (c) is an explanatory diagram showing the main parts of the light-emitting component.

[0036] Figure 2 This is an explanatory diagram showing the overall structure of the image forming apparatus according to the first embodiment;

[0037] Figure 3 This is an explanatory diagram showing an example of a light writing device used in the image forming apparatus of the first embodiment;

[0038] Figure 4 It is shown Figure 3 A perspective illustration of the structure of the optical writing device shown;

[0039] Figure 5 (a) is an explanatory diagram showing an array of light-emitting elements used in an optical writing device, and (b) is an explanatory diagram showing a structural example of a light-emitting chip used in an array of light-emitting elements.

[0040] Figure 6 (a) is an explanatory diagram showing a structural example of a light-emitting chip with an array of light-emitting elements used in the first comparison method, and (b) is an explanatory diagram showing an example of narrowing the arrangement spacing of the light-emitting element columns of the light-emitting chip shown in (a) in the structural example of a light-emitting chip with an array of light-emitting elements used in the first comparison method.

[0041] Figure 7 (a) is shown Figure 5 (b) is an explanatory diagram of the main part of (b), which schematically shows the light beam emitted from the light-emitting element;

[0042] Figure 8 This is an explanatory diagram showing an example of the structure of the light-emitting element used in the first embodiment;

[0043] Figure 9 (a) is an explanatory diagram showing an example of the wiring structure of the light-emitting element used in the first embodiment, (b) is an explanatory diagram of the cross-section of line BB in (a), and (c) is an explanatory diagram of the cross-section of line CC in (a).

[0044] Figure 10 This is a flowchart illustrating an example of driving control for an array of light-emitting elements;

[0045] Figure 11 (a) is an explanatory diagram showing a structural example of the imaging lens of the optical writing device used in the first embodiment, and (b) is a view viewed from the direction of arrow B in (a).

[0046] Figure 12 This is an explanatory diagram schematically showing the object point (the light-emitting point of the light-emitting element) and the image point (the imaging image formed by the imaging lens) of the optical writing device used in the first embodiment;

[0047] Figure 13 (a) is an explanatory diagram showing an example of an imaging image formed by the optical writing device used in the first embodiment, and (b) is an explanatory diagram showing an example of an imaging image formed by the optical writing device used in the first comparison mode.

[0048] Figure 14(a) is an explanatory diagram showing the incident state of light emitted from the light-emitting element array in the first embodiment and the first comparison mode when the imaging lens is set in an ideal position; (b) is an explanatory diagram showing the incident state of light emitted from the light-emitting element array in the first embodiment and the first comparison mode when the imaging lens is offset from the ideal position.

[0049] Figure 15 (a) is an explanatory diagram showing the incident state of light emitted from an offset-configured light-emitting chip in the light-emitting element array used in the first embodiment toward the imaging lens, and (b) is an explanatory diagram showing the incident state of light emitted from an offset-configured light-emitting chip in the light-emitting element array used in the first comparison mode toward the imaging lens.

[0050] Figure 16 This is an explanatory diagram showing the main part of the light-emitting element array used in the first modified mode;

[0051] Figure 17 (a) is an explanatory diagram showing the light intensity curve when an image of 2400 dpi is formed on a photoreceptor using the light writing device of the first embodiment, and (b) is an explanatory diagram showing a magnified photograph of a printed sample thereof. Detailed Implementation

[0052] Summary of Implementation Methods

[0053] Figure 1 (a) shows an outline of an embodiment of the image forming apparatus to which the present invention is applied.

[0054] In this figure, the image forming apparatus 10 includes: a light writing device 11; and an image holding unit 12, which is disposed opposite to the light writing device 11 and holds the light-based image written by the light writing device 11.

[0055] Here, the light writing device 11 includes a light-emitting component 1 and an imaging unit 6 that causes light emitted from each light-emitting element 4 of the light-emitting component 1 to form an image on an image holding unit 12 capable of holding a light-based image. The light writing device 11 writes the light-based image into the image holding unit 12.

[0056] The image holding unit 12 mentioned here is not limited to a photosensitive element, but also includes dielectrics, etc., and its shape can be appropriately selected as drum-shaped, strip-shaped, etc. In addition, light-based images can be exemplified by electrostatic latent images formed by removing the charge from an image pattern by light corresponding to the image pattern after the image has been charged to a specified level, thus creating a potential difference.

[0057] Furthermore, regarding the imaging unit 6, as long as the light emitted from each light-emitting element 4 of the light-emitting component 1 is imaged in the image holding unit 12, it can be a lens that refracts light on the surface (e.g., a cylindrical lens), or a lens that refracts light internally (e.g., a refractive index distribution lens), etc., can be appropriately selected.

[0058] In addition, such as Figure 1 As shown in (b), the light-emitting component 1 comprises: a first light-emitting element column 2, which is composed of light-emitting elements 4 arranged in the main scanning direction; and a second light-emitting element column 3, which is arranged in the main scanning direction such that it is offset relative to the first light-emitting element column 2 in the sub-scanning direction, and each light-emitting element 4 in the second light-emitting element column 3 is located between each light-emitting element 4 in the first light-emitting element column 2. Furthermore, as... Figure 1 As shown in (c), the light-emitting areas WA1 of each light-emitting element 4 in the first light-emitting element column 2 and the light-emitting areas WA2 of each light-emitting element 4 in the second light-emitting element column 3 are configured to overlap in the main scanning direction.

[0059] Here, a light-emitting element 4 can be exemplified, for example, by a light-emitting diode (LED). In this case, the light-emitting element 4 is specifically configured as a structure in which a p-anode layer, a light-emitting layer, and an n-cathode layer constituting the LED are stacked, and grooves are formed on the stacked layers such that the light-emitting element 4 becomes its respective light-emitting point. In this example, the light-emitting point regions WA1 and WA2 have the same width as the cathode layer of the LED, but this is not a limitation; it can also be configured to emit light in a narrower region within a current-narrowing layer provided in the p-anode layer.

[0060] Furthermore, the light-emitting element 4 is not limited to LED, but can also be VCSEL (Vertical Cavity Surface Emitting Laser), etc.

[0061] In such a technical approach, the present invention cannot be achieved simply by arranging a column of light-emitting elements 4 in the main scanning direction; therefore, it is predicated on including a first column of light-emitting elements 2 and a second column of light-emitting elements 3. However, it is not limited to arranging the first column of light-emitting elements 2 and the second column of light-emitting elements 3 in an alternating pattern; it is also envisioned to include a third column of light-emitting elements (not shown).

[0062] In addition, in this example, when the light-emitting component 1 of the light writing device 11 divides the image into multiple lines for writing, the movement in the direction of the line is called the main scan, and the movement in the direction of the next line is called the sub-scan.

[0063] Furthermore, the arrangement of the first light-emitting element column 2 and the second light-emitting element column 3 is exemplified by their arrangement along a straight line along the main scanning direction, but arrangements that are not aligned in a straight line are also included. For example, in a light-emitting element array comprising the first light-emitting element column 2 and the second light-emitting element column 3, which is composed of multiple light-emitting element chips, in which the multiple light-emitting element chips are arranged, for example, in an alternating configuration, the first light-emitting element column 2 and the second light-emitting element column 3 are not aligned in a straight line in the odd-numbered and even-numbered light-emitting element chips, but these arrangements are also included.

[0064] Furthermore, when creating a linear image using the first light-emitting element column 2 and the second light-emitting element column 3 of the light-emitting component 1, for example, considering the moving speed of the image holding unit 12 in the sub-scanning direction and the arrangement spacing of the first light-emitting element column 2 and the second light-emitting element column 3 in the sub-scanning direction, a delay circuit can be used, or the image writing timing can be appropriately staggered for drawing. Additionally, in the case of using multiple light-emitting element chips, further considering the arrangement spacing of the light-emitting element chips in the sub-scanning direction, it is necessary to adjust the image writing timing of the odd-numbered light-emitting element column and the even-numbered light-emitting element column.

[0065] Furthermore, in this embodiment, such as Figure 1 As shown in (c), electrodes 5 that prevent light from passing through are disposed on the surface of each light-emitting element 4 in the first light-emitting element row 2 and the second light-emitting element row 3. Therefore, in this example, the region inside the electrodes 5 becomes the region of the light-emitting beam emitted by the light-emitting element 4 and directed toward the object. Moreover, the light-emitting beam region W1 generated by each light-emitting element 4 in the first light-emitting element row 2 and the light-emitting beam region W2 generated by each light-emitting element 4 in the second light-emitting element row 3 are configured to have no gap in the main scanning direction.

[0066] Furthermore, the size of the light-emitting point area and the light-emitting beam area is determined by subtracting the width of the island used to separate the light-emitting parts, the width of the etching process, and the electrode width from the multilayer structure of the light-emitting element 4, so as to ensure the size of the opening that can emit light.

[0067] Thus, when the arrangement of the light-emitting elements 4 of the light-emitting component 1 in the main scanning direction is studied, the imaging image formed by the imaging unit 6 on the image holding unit 12 becomes an image of the light beam corresponding to the light-emitting point of each light-emitting element 4 of the light-emitting component 1.

[0068] Next, a representative or preferred embodiment of the light-emitting component will be described.

[0069] First, regarding the representative selection method for the arrangement spacing of the light-emitting points of the first light-emitting element column 2 and the second light-emitting element column 3, it can be listed that the arrangement spacing hp of the light-emitting points of each light-emitting element 4 of the first light-emitting element column 2 and the light-emitting points of each light-emitting element 4 of the second light-emitting element column 3 in the main scanning direction is less than 1 / 2 of the arrangement spacing between the light-emitting points of each light-emitting element 4 of the first light-emitting element column 2 and the second light-emitting element column 3 in the main scanning direction.

[0070] Here, in the case where the light-emitting component 1 only has the first light-emitting element column 2 and the second light-emitting element column 3, the maximum arrangement spacing is 1 / 2. However, in the case where, for example, a third light-emitting element column (not shown) is added in addition to the first light-emitting element column 2 and the second light-emitting element column 3, the arrangement spacing can be selected to be less than 1 / 2.

[0071] Furthermore, as a preferred arrangement of the light-emitting points relative to the main scanning direction, an example is that the overlap range of the light-emitting point areas of adjacent light-emitting elements 4 between the first light-emitting element column 2 and the second light-emitting element column 3 in the main scanning direction is between 30% and 70%. Simulation results show that this is because when the overlap is too large, even if the resolution is intentionally improved by offsetting in the sub-scanning direction, the effect on resolution improvement is small. In addition, when there are two columns in the sub-scanning direction, the space between the wiring and the light-emitting elements cannot be sufficiently ensured, and the current state becomes unstable. Furthermore, when there are three or more columns, the light-emitting device becomes larger in the sub-scanning direction, and such problems begin to occur when the overlap exceeds 65%. On the other hand, when the overlap is too small, a sufficient light-emitting point area cannot be ensured, and insufficient light intensity occurs when the overlap is less than 30%.

[0072] exist Figure 1 In example (c), the light-emitting elements are configured at 2400 dpi, so the light-emitting elements 4 in the first light-emitting element column 2 and the light-emitting elements 4 in the second light-emitting element column 3 are spaced 10.5 μm apart. Since the width of the cathode layer of the light-emitting elements is set to 15.4 μm, two adjacent light-emitting elements 4 in the second column overlap with one light-emitting element 4 in the first column, so the overlapping area is 63.6%. In addition, the reason for setting it to a value that overlaps more on one side rather than the center value is also related to the fact that the electrodes are configured in this embodiment to cover the light emitted from the light-emitting point area.

[0073] In addition, such as Figure 1As shown in (c), the inner dimension of the electrode with electrode 5 is 10.6 μm, which is approximately equivalent to a spacing of 2400 dpi. In the light-emitting element 4, although the entire area of ​​the light-emitting point region emits light, the light intensity is weaker near the sides and stronger in the central part. It can also be said that the light-emitting area is in a state where the light intensity is stabilized by the electrode 5 due to increased overlap and a wider spacing. However, when the spacing is smaller, especially when the spacing is narrower than 2400 dpi, the possibility of insufficient light intensity is still relatively high. It is advisable to set it to a state of slight overlap, which is slightly less than zero overlap with no gap. However, from the point of view of resolution, it is advisable to set it to within 10%.

[0074] Furthermore, as a preferred arrangement of the light-emitting points relative to the sub-scanning direction, it can be listed that the arrangement spacing of the light-emitting points of each light-emitting element 4 in the first light-emitting element column 2 and the light-emitting points of each light-emitting element 4 in the second light-emitting element column 3 along the sub-scanning direction is an integer multiple of the imaging line interval N. According to this example, if it is selected to be an integer multiple of the imaging line interval N lines apart, by staggering the writing timing by N lines, it is possible to write an image of the same line through the first light-emitting element column 2 and the second light-emitting element column 3.

[0075] Furthermore, as a preferred embodiment of the imaging unit 6 of the light writing device 11, one example is a configuration in which a refractive index distribution lens with a diameter greater than the difference between the sub-scanning directions of the first light-emitting element column 2 and the second light-emitting element column 3 is arranged in the main scanning direction. In this example, a refractive index distribution lens is used as the imaging unit 6, so that light from each of the light-emitting elements 4 of the first light-emitting element column 2 and the second light-emitting element column 3 is incident on the same refractive index distribution lens.

[0076] Here, in the method of using a refractive index distribution lens as the imaging unit 6, the emitted light from the first light-emitting element column 2 and the second light-emitting element column 3 only needs to be incident at different positions relative to the refractive index distribution lens in the sub-scanning direction.

[0077] Furthermore, there are multiple light-emitting element chips (not shown), including a first light-emitting element column 2 and a second light-emitting element column 3. These multiple light-emitting element chips are offset in both the sub-scanning direction and the main scanning direction. The imaging unit 6 is formed by arranging refractive index distribution lenses adjacent to each other in multiple columns in the main scanning direction. Light from each light-emitting element 4 of the same light-emitting element chip is incident on a refractive index distribution lens arranged in the same column in the main scanning direction, while light from each light-emitting element 4 of adjacent light-emitting element chips is incident on refractive index distribution lenses in different columns. This example describes a method of allocating multiple refractive index distribution lenses to the light path from the offset light-emitting element chips in a way that involves offsetting the multiple light-emitting element chips and using multiple columns of refractive index distribution lenses. When light emitted from two light-emitting element chips is incident on refractive index distribution lenses in the same column, the difference in light path length from the two light-emitting element chips becomes larger, and the imaging characteristics are prone to deviation. In contrast, this method is preferred in terms of suppressing such effects.

[0078] The present invention will now be described in more detail based on the embodiments shown in the accompanying drawings.

[0079] First Implementation Method

[0080] <Overall Structure of the Image Forming Apparatus>

[0081] Figure 2 The overall structure of the image forming apparatus according to the first embodiment is shown.

[0082] In this figure, the image forming apparatus 20 is commonly referred to as a tandem type image forming apparatus. The image forming apparatus 20 includes: an image forming processing unit 21, which forms images corresponding to image data of each color; an image output control unit 40, which controls the image forming processing unit 21; and an image processing unit 50, which is connected, for example, to a personal computer (PC) 61 and an image reading device 62, and performs predetermined image processing on the image data received from the personal computer 61 and the image reading device 62.

[0083] The image forming processing unit 21 includes image forming units 22 arranged side-by-side at a certain interval. These image forming units 22 consist of four imaging engines 23 (23a to 23d), which are examples of toner image forming units that form toner images of four colors (yellow (Y), magenta (M), cyan (C), and black (K) in this example). Each imaging engine 23 (23a to 23d) includes, for example, a drum-shaped photoreceptor 24, which forms an electrostatic latent image to hold the toner image; a charger 25 that uniformly charges the surface of the photoreceptor 24 at a predetermined potential; a light writing device 26 that exposes the photoreceptor 24 charged by the charger 25 to form an electrostatic latent image; and a developer 27 that develops the electrostatic latent image formed by the light writing device 26. Furthermore, the imaging engines 23 (23a to 23d) form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively.

[0084] In addition, in order to transfer the toner images of various colors formed on the photoreceptors 24 of each imaging engine 23 (23a to 23d) onto the recording paper 29, which is an example of a recording medium, the image forming processing unit 21 includes a paper conveyor belt 31 for conveying the recording paper, a transfer unit (in this example, a transfer roller) 28 for transferring the toner images of the photoreceptors 24 onto the recording paper, and a fuser 32 for fixing the toner images onto the recording paper.

[0085] In this image forming apparatus 20, the image forming processing unit 21 performs image forming operations based on various control signals supplied from the image output control unit 40. Furthermore, under the control of the image output control unit 40, the image processing unit 50 performs image processing on image data received from the personal computer (PC) 61 and the image reading device 62, and supplies it to the imaging engine 23. Moreover, for example, in the black (K) imaging engine 23d, the photoreceptor 24 rotates in the direction of the arrow while being charged to a predetermined potential by the charge carrier 25, and is exposed by the light writing device 26, which emits light based on the image data supplied from the image processing unit 50. Thus, an electrostatic latent image associated with the black (K) image is formed on the photoreceptor 24. Furthermore, the electrostatic latent image formed on the photoreceptor 24 is developed by the developer 27, forming a black (K) toner image on the photoreceptor 24. Similarly, in each of the imaging engines 23 (23a to 23c), toner images of yellow (Y), magenta (M), and cyan (C) are also formed respectively.

[0086] The toner images formed by each imaging engine 23 (23a to 23d) on the photosensitive body 24 are electrostatically transferred sequentially to the recording paper 29, which is supplied as the paper conveyor belt 31 moves along the direction of the arrow, by the transfer electric field applied to the transfer unit 28 (transfer roller), forming a composite toner image with each toner superimposed on the recording paper 29.

[0087] Subsequently, the recording paper 29 with the synthetic toner image electrostatically transferred is conveyed to the fuser 32. The synthetic toner image on the recording paper 29 conveyed to the fuser 32 is fixed onto the recording paper 29 by a heat and pressure-based fixing process in the fuser 32 and discharged from the image forming apparatus 20.

[0088] <Example of the structure of an optical writing device>

[0089] Figure 3 This diagram shows a structural example of the optical writing device 26 using this embodiment. Figure 4 A three-dimensional illustration is shown.

[0090] In this figure, the light writing device 26 includes: a device housing 71; a light-emitting element array 72 held in the device housing 71, having a plurality of LEDs as light-emitting elements; and an imaging lens 73, which is an example of an imaging unit, held in the device housing 71, so that light emitted from the light-emitting elements of the light-emitting element array 72 is output to image the photoreceptor 24 to expose it and form an electrostatic latent image.

[0091] In this example, the device housing 71 is formed of, for example, metal, and holds the light-emitting element array 72 and the imaging lens 73, such that the light-emitting point L of the light-emitting element 80 of the light-emitting element array 72 is aligned with the focal plane of the imaging lens 73. Furthermore, the imaging lens 73 is arranged along the axial direction of the photoreceptor 24 (corresponding to the main scanning direction).

[0092] Additionally, the light-emitting element array 72 is connected to the signal generating circuit 76 via the flexible substrate 74 (see reference). Figure 9 (a)) is connected to the control board 75.

[0093] <Example of a structure for an array of light-emitting elements>

[0094] Figure 5 (a) shows a structural example of the light-emitting element array 72.

[0095] In this figure, the light-emitting element array 72 is configured such that multiple light-emitting element chips C (C1 to Cn) are arranged in a staggered manner in two opposing columns on the circuit board 90 in the main scanning direction, and light-emitting elements 80 are arranged side by side on each light-emitting element chip C (C1 to Cn) along the main scanning direction. Furthermore, by directly connecting the signal generation circuit 76 mounted on the control board 75 to each light-emitting element 80 of the multiple light-emitting element chips C, the signal generation circuit 76 controls the light emission of each light-emitting element 80.

[0096] In addition, in this example, the light-emitting element chips C are arranged in an alternating pattern to avoid the situation where the spacing of the light-emitting elements 80 cannot be fixed at the ends of the light-emitting element chips C when multiple light-emitting element chips C are arranged in one direction.

[0097] -Light-emitting element chip-

[0098] Figure 5 (b) shows a structural example of the light-emitting element chip C (Ci to Ci+2).

[0099] In this figure, the light-emitting element chip C is configured such that, in the light-emitting element chip C mounted on the light-emitting element array 72, the odd-numbered light-emitting element chip C (Ci, Ci+2 in this example: i is odd) includes: a first light-emitting element column 82 composed of light-emitting elements 80 arranged in the main scanning direction in a region on the chip substrate 81 near the even-numbered light-emitting element chip C (Ci+1 in this example: i is odd); and a second light-emitting element column 83 which is offset relative to the first light-emitting element column 82 by being arranged in the main scanning direction, and wherein each light-emitting element 80 is located between the light-emitting elements 80 of the first light-emitting element column 82.

[0100] On the other hand, the even-numbered light-emitting element chip C (Ci+1 in this example: i is odd) includes: a first light-emitting element column 82 composed of light-emitting elements 80 arranged in the main scanning direction in a region on the chip substrate 81 near the odd-numbered light-emitting element chip C (Ci, Ci+2 in this example: i is odd); and a second light-emitting element column 83 arranged in the main scanning direction in a manner that is offset relative to the first light-emitting element column 82 in the sub-scanning direction and located between the light-emitting elements 80 of the first light-emitting element column 82.

[0101] In this example, when the arrangement spacing (equivalent to the distance between the center lines of the main scanning directions of adjacent light-emitting elements 80) of each light-emitting element 80 in the first light-emitting element column 82 and the second light-emitting element column 83 is set to P, the arrangement spacing along the main scanning direction between the light-emitting elements 80 of the first light-emitting element column 82 and the light-emitting elements 80 of the adjacent second light-emitting element column 83 is P / 2.

[0102] Furthermore, in this example, the distance xc between the center line position of the main scanning direction of the light-emitting element 80 located at the very end (right end in the figure) of the odd-numbered light-emitting element chip C (e.g., Ci) and the center line position of the main scanning direction of the light-emitting element 80 located at the very beginning (left end in the figure) of the adjacent even-numbered light-emitting element chip C (e.g., Ci+1) is selected to be consistent with the arrangement spacing P / 2. Additionally, the distance xc between the center line position of the main scanning direction of the light-emitting element 80 located at the very beginning of the odd-numbered light-emitting element chip C (e.g., Ci+2) and the center line position of the main scanning direction of the light-emitting element 80 located at the very end of the adjacent even-numbered light-emitting element chip C (e.g., Ci+1) is also selected to be consistent with the arrangement spacing P / 2.

[0103] Furthermore, when the centroid position of the light-emitting point L at the center of the sub-scanning direction between the first light-emitting element column 82 and the second light-emitting element column 83 connecting the odd-numbered light-emitting element chips C (Ci, Ci+2) is set to m1, and the centroid position of the light-emitting point L at the center of the sub-scanning direction between the first light-emitting element column 82 and the second light-emitting element column 83 connecting the even-numbered light-emitting element chips C (Ci+1) is set to m2, the offset distance yc of the sub-scanning direction of the adjacent light-emitting element chips C is selected as |m1-m2|.

[0104] <Example of the arrangement of light-emitting elements in the first and second light-emitting element rows>

[0105] An example of the arrangement of light-emitting elements 80 in the first light-emitting element column 82 and the second light-emitting element column 83 will be described. First, the case of narrowing the arrangement spacing in the example of the arrangement of light-emitting elements in the light-emitting element array of the first comparison mode will be described.

[0106] First comparison method

[0107] In the first comparison mode of the light-emitting element array 72', for example, even if the light-emitting element chips are arranged in an interlaced pattern, but as Figure 6 As shown in (a), each light-emitting element chip is also formed by arranging the light-emitting elements 80 in a row with an arrangement spacing P in the main scanning direction.

[0108] At this time, the light-emitting points L of the light-emitting element 80 are arranged at equal intervals P in the main scanning direction x. Here, in order to separate the light-emitting island 91 corresponding to the light-emitting point area of ​​the adjacent light-emitting element 80, a width of 2a is required. When separating the light-emitting element 80 by wet etching, when the etching depth is set to e, a > e is required. Furthermore, in this example, an electrode 92 that does not allow light to pass through is disposed on the surface of the light-emitting element 80. Since the light emission under the electrode 92 is not extracted, it is necessary to ensure that the width 2b of the electrode 92 is a non-light-emitting area. Therefore, it can be understood that in the area of ​​the light-emitting island 91 of the light-emitting element 80, the area that can actually emit light (equivalent to the light beam area) W is P-2a-2b.

[0109] Now, at 1200 dpi (dots per inch), when P = 21.2 μm, a = 2 μm, and b = 2.5 μm, W = 21.2 - 4 - 5 = 12.2 μm.

[0110] Next, in the light-emitting element array 72' of the first comparison mode, assuming the arrangement spacing between the light-emitting elements 80 is set to P / 2 (equivalent to 2400 dpi), then as Figure 6 As shown in (b), P / 2 = 10.6 μm. Therefore, after subtracting the width 2a of the light-emitting island 91 for separation and the width 2b of the electrode 92, the width of the actual light-emitting area (light beam area) W of the light-emitting point L is 10.6 - 4 - 5 = 1.6 μm. Thus, the width of the actual light-emitting area W of the light-emitting point L is greater than... Figure 6 The case shown in (a) is smaller than 1.6 / 12.2 = 1 / 7.6. In this case, the hiding ratio of electrode 92 relative to the light-emitting island 91 also increases, and the luminous efficiency decreases. Therefore, the increased current density due to the increase in current corresponding to the decrease in luminous efficiency and the reduction in light-emitting area becomes the main reason for the deterioration of the light-emitting element 80, and the reliability of the light-emitting element 80 decreases.

[0111] In contrast, in the implementation method, such as Figure 7 As shown in (a), each light-emitting element chip C has a first light-emitting element column 82 and a second light-emitting element column 83, and the arrangement spacing of each light-emitting element 80 in the first light-emitting element column 82 and the second light-emitting element column 83 along the main scanning direction is P.

[0112] Furthermore, the arrangement spacing along the main scanning direction between the light-emitting elements 80 of the first light-emitting element column 82 and the light-emitting elements 80 of the adjacent second light-emitting element column 83 is P / 2. In addition, the distance p between the two in the sub-scanning direction (in this example, the distance between the center lines of each light-emitting element 80 in the sub-scanning direction) is selected as an integer multiple of the line spacing N.

[0113] Furthermore, in this example, in the light-emitting points L (L1, L2) of each light-emitting element 80 in the first light-emitting element row 82 and the second light-emitting element row 83, the areas that can actually emit light are ensured to be the same as those in the light-emitting element array 72' used in the first comparison method. That is, in the light-emitting points L (L1, L2), the area inside the electrode 92 is the light-emitting beam area W in this example (specifically W1 and W2, where W1 = W2 in this example).

[0114] Furthermore, in this example, the light emission beam region W1 of each light emission element 80 in the first light emission element column 82 and the light emission beam region W2 of each light emission element 80 in the second light emission element column 83 are configured to have no gap in the main scanning direction.

[0115] Furthermore, the light beam region W1 of the light-emitting point L (L1) of the light-emitting element 80 of the first light-emitting element column 82 is selected to overlap by only ΔW in the main scanning direction with respect to the light beam region W2 of the light-emitting point L of the light-emitting element 80 of the second light-emitting element column 83. In this example, ΔW is selected as, for example, 0.05% of the light beam regions W (W1, W2) of the light-emitting point L. Here, when ΔW is a negative value less than 0, the overlap of adjacent light-emitting points L in the main scanning direction between the first light-emitting element column 82 and the second light-emitting element column 83 can easily become unstable. In addition, when ΔW exceeds 10% of W, the light emitted from the light-emitting point L overlaps too much, which may easily affect the resolution of the light-emitting point L unit.

[0116] Therefore, in this example, the light emitted from adjacent light-emitting points L between the first light-emitting element column 82 and the second light-emitting element column 83 is schematically shown as a circle with beam diameters d (specifically d1, d2) in the main scanning direction, and the overlap ΔW of the light-emitting points L roughly corresponds to the overlapping region OL.

[0117] Furthermore, since the adjacent light-emitting elements 80 between the first light-emitting element column 82 and the second light-emitting element column 83 are separated by p in the sub-scanning direction, in order to create an image arranged in a straight line on the photoreceptor 24, it is only necessary to use an imaging timing or delay circuit offset by N lines to draw the image.

[0118] -Example of cross-sectional structure of a light-emitting element chip-

[0119] In this example, such as Figure 8As shown, the light-emitting element chip C uses a self-scanning light-emitting element (SLED). A p-anode layer 101, a light-emitting layer 102, and an n-cathode layer 103 constituting a light-emitting diode (LED) are stacked on a p-type substrate 100. Grooves are formed on the layers stacked in such a way that the light-emitting elements 80 become each light-emitting point. A p-anode layer 105, an n-gate layer 106, a p-gate layer 107, and an n-cathode layer 108 constituting a set thyristor S are stacked through a tunnel bonding layer 104.

[0120] Furthermore, the thyristor S is configured to use an n-ohm electrode 111 disposed on the n-cathode layer 108 as the cathode electrode, and a p-type ohm electrode 112 disposed on the p-gate layer 107 exposed after the n-cathode layer is removed as the gate electrode. In addition, the p-anode layer 101 is composed of a lower p-anode layer 101a, a current-restricting layer 101b, and an upper p-anode layer 101c.

[0121] In this example, the light-emitting point regions WA1 and WA2 are the same width as the n-cathode layer 103 of the light-emitting diode (LED). That is, the width of the n-cathode layer 103 is configured to emit light across the entire width of the n-cathode layer 103, which corresponds to the outer periphery of a light-emitting element 80, and is thus considered as the light-emitting point regions WA1 and WA2. However, the present invention is not limited to this. For example, it may be configured to reduce the light-emitting point regions WA1 and WA2 by setting a narrower region in the current narrowing layer 101b so that only the central portion of the light-emitting element 80 emits light.

[0122] Furthermore, as indicated by the arrow, the light-emitting diode (LED) emits light in a direction orthogonal to the substrate 100. Therefore, it can be used when using light emitted in a direction orthogonal to the substrate 100. Moreover, the central portion of the n-ohm electrode 111 is open, so light is emitted through the tunnel junction layer 104.

[0123] Alternatively, a current-restricting layer can be provided on the p-anode layer 105 of the thyristor S. In addition, a current-restricting layer can also be provided on the n-cathode layer 103 of the light-emitting diode LED and the n-cathode layer 108 of the thyristor S.

[0124] Thus, in this example, the light-emitting beam region W (W1, W2) of the light-emitting point L of the light-emitting element 80 is determined by the width of the current narrow layer 101b and the diameter of the opening of the n-ohm electrode 111 in the light emission direction.

[0125] - Wiring structure to the light-emitting element-

[0126] In this example, such as Figure 9As shown in (a), gate electrodes 120 for providing a light-emitting start signal from the signal generation circuit 76 are respectively connected to the light-emitting points L (specifically L1, L2) of each light-emitting element 80 in the first light-emitting element column 82 and the second light-emitting element column 83.

[0127] Here, the light-emitting point L (specifically, L1) of the light-emitting element 80 of the first light-emitting element row 82 is connected via the gate electrode 120 on the gate semiconductor layer 121.

[0128] Furthermore, regarding the light-emitting point L (specifically, L2) of the light-emitting element 80 in the second light-emitting element column 83, the gate electrode needs to be wired in a manner that passes through the area between the light-emitting elements 80 in the first light-emitting element column 82. However, similar to the first light-emitting element column 82, when the gate electrode is wired between each light-emitting element 80, the gate electrode may come into contact with the light-emitting element 80 in the first light-emitting element column 82.

[0129] Therefore, in this example, as Figure 9 As shown in (b) and (c), each light-emitting element 80 of the first light-emitting element column 82 and the area between each light-emitting element 80 are covered with a permeable insulating film 122 (e.g., silicon). Under the insulating film 122, electrode terminals 123 are provided to connect with the light-emitting points L (specifically, L2) of each light-emitting element 80 of the second light-emitting element column 83. In the insulating film 122, a split gate electrode 124 is provided in the area between the light-emitting elements 80 of the first light-emitting element column 82. Contact holes 125 and 126 are respectively opened at the light-emitting element 80 side ends of the electrode terminals 123 and the split gate electrode 124. Metal wiring 127 is laid between the contact holes 125 and 126 on the insulating film 122, and the metal wiring 127 is connected to the electrode terminals 123 and the split gate electrode 124 through the contact holes 125 and 126.

[0130] In this example, the wiring structure for each light-emitting element 80 of the second light-emitting element column 83 can be implemented without narrowing the width of the light-emitting point area L (L1, L2) of each light-emitting element 80 of the first light-emitting element column 82 and the second light-emitting element column 83.

[0131] <Drive Control of Light Emitting Element Array>

[0132] Figure 10 A flowchart is shown for driving control of the light-emitting element array in this example.

[0133] First, image data DT with the main scan line j is read into the signal generation circuit 76 of the control substrate 75. This image data DT is a signal start signal provided to each light-emitting element 80 of each light-emitting element chip C of the light-emitting element array 72.

[0134] First, it is determined whether the light-emitting element chip C is an odd-numbered column. Then, it is determined whether the light-emitting point L of each light-emitting element 80 is in the first column (first light-emitting element column 82). As a result, the image data DT from the signal generation circuit 76 is supplied to the light-emitting elements 80 divided into the following four columns.

[0135] (1) The light-emitting element chip C is in an odd-numbered column, and the light-emitting point is in the first column.

[0136] (2) The light-emitting element chip C is in an odd-numbered column, and the light-emitting point is in the second column.

[0137] (3) The light-emitting element chip C is in an even-numbered column, and the light-emitting point is in the first column.

[0138] (4) The light-emitting element chip C is in an even-numbered column, and the light-emitting point is in the second column.

[0139] Here, in the case of (1), such as Figure 5 As shown in (b), the light-emitting point L1 of the first column of the light-emitting element 80 of the odd-numbered light-emitting element chip C is used as the object for driving, and the light-emitting timing is set to A.

[0140] Furthermore, in case (2), such as Figure 5 As shown in (b), the light-emitting point L2 of the second column of the light-emitting element 80 of the odd-numbered light-emitting element chip C is used as the target for driving, and the light-emitting timing is set to B. Compared with setting A, in setting B in this example, the light-emitting timing is adjusted by considering the distance p (an integer multiple of the line distance N) of the sub-scanning direction of the light-emitting element 80 between the first light-emitting element column 82 and the second light-emitting element column 83.

[0141] Furthermore, in case (3), such as Figure 5 As shown in (b), the light-emitting point L1 of the first column of the even-numbered light-emitting element chip C is used as the target for driving, and the light-emitting timing is set to C. Compared to setting A, in setting C in this example, the distance g in the sub-scanning direction between the light-emitting elements 80 of the first column of the odd-numbered light-emitting element chip C and the light-emitting elements 80 of the first column of the even-numbered light-emitting element chip C (equivalent to...) is considered. Figure 5 In B (yc), adjust the timing of the light emission.

[0142] Furthermore, in case (4), such as Figure 5 As shown in (b), the light-emitting point L2 of the second column of the even-numbered light-emitting element chip C is used as the target for driving, and the light-emitting timing is set to D. Compared with setting A, in setting D in this example, the distance h in the sub-scanning direction between the light-emitting elements 80 of the first column of the odd-numbered light-emitting element chip C and the light-emitting elements 80 of the second column of the even-numbered light-emitting element chip C is considered, and the light-emitting timing can be adjusted accordingly.

[0143] <Imaging Lens>

[0144] In this example, in imaging lens 73, as Figure 3 , Figure 4 as well as Figure 11 As shown in (a) and (b), a lens holder 130 is formed by a pair of side plates 131 extending along the axial direction of the photoreceptor 24 and abutment plates 132 at both ends between the closed side plates 131. In the space of this lens holder 130, cylindrical refractive index distribution lenses 135 extending between the light-emitting element array 72 and the photoreceptor 24 are arranged in an array in two adjacent rows along the axial direction of the photoreceptor 24 (corresponding to the main scanning direction). Furthermore, the peripheral walls of the refractive index distribution lenses 135 are covered by a protective layer such as resin. Moreover, the number of rows of refractive index distribution lenses 135 is not limited to two; it can be three or more rows, or even just one row.

[0145] In this example, the refractive index distribution lens 135 sets a conjugate length TC between the light-emitting point L (equivalent to the object point) of the light-emitting element array 72 and the image point on the photoreceptor 24, so that the light emitted from the light-emitting point L is incident, passes through the interior of the lens through the refractive index distribution and is emitted, and converges at the image point.

[0146] In this example, the length of the refractive index distribution lens 135 is Z0, the distance to the light source L is L0, and the distance to the image point is Li. The lens diameter D is selected to be more than 4 times larger than the beam diameter d (e.g., 10 μm) of the light source L (e.g., 40 to 45 μm).

[0147] Furthermore, in the imaging lens 73, the refractive index distribution type lens 135 is arranged in two columns of a lens array with a total width Wt, which is selected to be greater than or equal to the effective image width Wi.

[0148] <Relationship between luminous point and image point>

[0149] In this example, such as Figure 12 As shown, the light-emitting points L (specifically L1, L2) of each light-emitting element 80 in the light-emitting element array 72 emit light along the main scanning direction of adjacent light-emitting elements 80 between the first light-emitting element column 82 and the second light-emitting element column 83 with an arrangement spacing P / 2.

[0150] In this state, the light emitted from the light-emitting point L is imaged onto the photoreceptor 24 via the imaging lens 73.

[0151] At this time, when the light-emitting element array 72 depicts an image (line image) formed by straight lines of light extending along the main scanning direction, such as Figure 12As shown, the imaging image G on the photoreceptor 24 is formed by dots with an arrangement spacing of P / 2, but the dot-shaped imaging images G overlap each other at adjacent positions. In this state, the dot-shaped imaging images G are drawn in a manner that overlaps with the beam diameter d of the light-emitting points L of the light-emitting element array 72 in the main scanning direction to approximately the same degree. Through the overlap of the dot-shaped imaging images G, the light intensity distribution of the dot-shaped imaging images G is increased.

[0152] Additionally, in this example, if P is, for example, 1200 dpi, then P / 2 represents 2400 dpi.

[0153] <Image quality>

[0154] -First Implementation Method-

[0155] In the first embodiment, light emitted from adjacent light-emitting points L (L1, L2) is imaged onto the photoreceptor 24 via the imaging lens 73.

[0156] At this time, as Figure 13 As shown in (a), the imaging beam regions of the adjacent point-like imaging images G corresponding to the adjacent luminous points L (L1, L2) are depicted in a partially overlapping manner, and the light intensity distribution of the point-like imaging images G is increased, depicting a normal concentration image.

[0157] Now, assuming that the luminescence characteristics of a portion of the luminescent point L are deviated, then as follows: Figure 13 As shown in (a), for the deviation of the luminescence characteristics of one luminescence point L, the amount of light is increased by overlapping the imaging image G formed by the adjacent luminescence points L with normal luminescence characteristics, thus correcting the quality of the imaging image G corresponding to the luminescence point L with the deviation in luminescence characteristics to some extent.

[0158] -First Comparison Method-

[0159] In contrast, the light-emitting element array using the first comparison method (refer to...) Figure 6 In the case of ( ), the beam diameters of adjacent luminous points L in the main scanning direction do not overlap. Therefore, the imaging image G corresponding to luminous point L directly depends on the luminous characteristics of the luminous point. That is, when the luminous characteristics of luminous point L are normal, such as Figure 13 As shown in (b), the dotted imaging image G depicts a normal concentration image, but when the luminescence characteristics of the luminescent point L are deviated, such as... Figure 13 As shown in (b), the light distribution of the point-like imaging image G is insufficient, for example, it may not be possible to obtain sufficient image density.

[0160] -Influence of Imaging Lens Layout-

[0161] Now, assuming that the imaging lens 73 is set in an ideal position, in either the first embodiment or the first comparison method, when drawing a straight line image extending along the main scanning direction using the light-emitting element array 72, light emitted from the light-emitting point L of the light-emitting element array 72 along the center position of the arrangement direction of the refractive index distribution type lens 135 constituting the imaging lens 73 is incident.

[0162] In the first embodiment, the light-emitting element array 72 writes a light image in the first light-emitting element column 82 and the second light-emitting element column 83 by emitting points L arranged at a spacing P, and depicts the image with a spacing of P / 2 relative to the main scanning direction. Figure 14 As shown in (a), it is possible to ensure a large luminous area of ​​the luminous point L, and by making the diameters of the light beams emitted from the luminous point L partially overlap, it is possible to image a large amount of light on the side of the photoreceptor 24.

[0163] Additionally, in the light-emitting element array of the first comparison method, such as Figure 6 As shown in (b), when the light-emitting points L are arranged with a spacing of P / 2, the light-emitting area of ​​the light-emitting points L is small and the amount of light emitted from the light-emitting points L is also small.

[0164] -Tilting and shifting of the imaging lens-

[0165] Furthermore, when setting the imaging lens 73, the imaging lens 73 may tilt or shift.

[0166] In such a situation, such as Figure 14 As shown in (b), light emitted from the light-emitting point L of the light-emitting element array 72 is incident on a position offset from the center line of the arrangement direction of the refractive index distribution lens 135.

[0167] At this time, in the light-emitting element array 72 of the first embodiment, a large light-emitting area of ​​the light-emitting point L can be ensured, and by making the diameters of the light beams emitted from the light-emitting point L partially overlap, a light image with a large amount of light can be imaged on the photoreceptor 24 side. Therefore, even if the amount of light that can be picked up is slightly reduced due to the tilt θ or offset of the imaging lens 73, it is compensated by the increase in the amount of light caused by the overlap of the beam diameters, thus mitigating the reduction in the amount of light in the light image.

[0168] In this regard, in the light-emitting element array of the first comparison method, since there is no light amount filling as in the first embodiment, the quality of the image may be directly affected when the amount of light that can be picked up is reduced due to the tilt or offset of the imaging lens 73.

[0169] -Incident mode of imaging lenses based on staggered configuration of light-emitting element chips-

[0170] In this embodiment, the light-emitting element array 72 arranges multiple light-emitting element chips C in an alternating pattern. On each light-emitting element chip C, a first light-emitting element column 82 and a second light-emitting element column 83 are arranged in the main scanning direction with an arrangement spacing P. Furthermore, the light-emitting points L of adjacent light-emitting elements 80 between the first light-emitting element column 82 and the second light-emitting element column 83 are arranged in the main scanning direction with an arrangement spacing of P / 2, and the diameters of the light beams emitted from the light-emitting points L partially overlap.

[0171] Therefore, in the implementation method, such as Figure 15 As shown in (a), in the light-emitting element chip C, light Bm1 emitted from the light-emitting point L located in the odd-numbered light-emitting element chip C passes through the first column of refractive index distribution type lens 135, while light Bm2 emitted from the light-emitting point L located in the even-numbered light-emitting element chip C passes through the second column of refractive index distribution type lens 135.

[0172] In this way, the light emitted from the staggered light-emitting element chips C is distributed and incident on the first and second columns of refractive index distribution lenses 135. The amount of incident light at this time is compared with the light-emitting element array in the first comparison mode (see...). Figure 15 Compared to (b), this ensures a greater amount of overlap in the diameter of the beams from the emitting point L.

[0173] Furthermore, even when the imaging lens 73 is tilted or offset, since the lens diameter D of the refractive index distribution lens 135 is sufficiently larger than the beam diameter, the light emitted from the staggered light-emitting element chips C is distributed and incident on the first and second columns of the refractive index distribution lenses 135, thereby enabling the imaging characteristics formed by the imaging lens 73 to be obtained.

[0174] First transformation method

[0175] Figure 16 The main part of the light-emitting element array in the first deformation mode is shown.

[0176] In this figure, the light-emitting element array 72 has a plurality of light-emitting element chips C arranged in an alternating manner, similar to the first embodiment. However, unlike the first embodiment, each light-emitting element chip C has a first light-emitting element column 82, a second light-emitting element column 83, and a third light-emitting element column 84.

[0177] In this example, the odd-numbered light-emitting element chip C (Ci, Ci+2, where i is odd) has a first light-emitting element column 82, a second light-emitting element column 83, and a third light-emitting element column 84, which are located from the position away from the even-numbered light-emitting element chip C (Ci+1, where i is odd) and are located towards the position of approach.

[0178] In this example, the first to third light-emitting element columns 82, 83, and 84 are formed by arranging light-emitting elements 80 along the main scanning direction with an arrangement spacing P.

[0179] Furthermore, the light-emitting elements 80 of the first light-emitting element column 82 and the light-emitting elements 80 of the second light-emitting element column 83 are arranged with an arrangement spacing P / 3 in the main scanning direction, and the light-emitting elements 80 of the second light-emitting element column 83 and the light-emitting elements 80 of the third light-emitting element column 84 are arranged with an arrangement spacing P / 3 in the main scanning direction.

[0180] Furthermore, the light-emitting points L (specifically, L1) of the light-emitting elements 80 in the first light-emitting element column 82 and the light-emitting points L (specifically, L2) of the light-emitting elements 80 in the second light-emitting element column 83 are arranged to partially overlap in the main scanning direction. In addition, the light-emitting points L (specifically, L2) of the light-emitting elements 80 in the second light-emitting element column 83 and the light-emitting points L (specifically, L3) of the light-emitting elements 80 in the third light-emitting element column 84 are arranged to partially overlap in the main scanning direction.

[0181] Furthermore, the first to third light-emitting element columns 82, 83, and 84 are configured with an integer N-fold spacing relative to the sub-scanning direction spacing line interval.

[0182] In addition, the even-numbered light-emitting element chip C (Ci+1, i is odd) has a first light-emitting element column 82, a second light-emitting element column 83, and a third light-emitting element column 84 from the position close to the odd-numbered light-emitting element chip C (Ci, Ci+2, i is odd) toward the position away from it.

[0183] Here, the structure of the first to third light-emitting element columns 82, 83, and 84 is roughly the same as that of the odd-numbered light-emitting element chip C.

[0184] In addition, Figure 16 In this example, xc represents the distance between the center line position of the main scanning direction of the first light-emitting element 80 located in the odd-numbered light-emitting element chip C (e.g., Ci+2) and the center line position of the main scanning direction of the last light-emitting element 80 located in the even-numbered light-emitting element chip C (e.g., Ci+1) adjacent to it. In this example, it is selected to be consistent with the arrangement spacing P / 3.

[0185] Furthermore, when the centroid position of the light-emitting point L at the center of the sub-scanning direction of the second light-emitting element column 83 connecting the odd-numbered light-emitting element chips C (Ci, Ci+2) is set to m1, and the centroid position of the light-emitting point L at the center of the sub-scanning direction of the second light-emitting element column 83 connecting the even-numbered light-emitting element chips C (Ci+1) is set to m2, the offset distance yc of the sub-scanning direction of the adjacent light-emitting element chips C is selected as |m1-m2|.

[0186] According to this embodiment, in each light-emitting element chip C of the light-emitting element array 72, three columns of light-emitting elements 82 to 84 are provided. The first column of light-emitting elements 82 is assigned light-emitting points L of 1, 4, 7... (specifically, L1), the second column of light-emitting elements 83 is assigned light-emitting points L of 2, 5, 8... (specifically, L2), and the third column of light-emitting elements 84 is assigned light-emitting points L of 3, 6, 9... (specifically, L3).

[0187] Therefore, in this example, by adjusting the timing of the light emission of the light emission points L in the three columns of light emission elements 82 to 84 in each light-emitting element chip C, an image can be formed on the photoreceptor 24.

[0188] In particular, in this example, if P is set to 800 dpi, then P / 3 = 2400 dpi, and thus, similar to the first embodiment, an image of 2400 dpi can be formed.

[0189] In addition, in this example, the light-emitting element chip C has three columns of light-emitting elements 82 to 84, but the present invention is not limited to this, for example, four or more columns of light-emitting elements may also be used.

[0190] 【Example】

[0191] First Embodiment

[0192] This example embodies the image forming apparatus of the first embodiment, and uses an example of light intensity curves of the light-emitting element array of the light writing device and a printed sample.

[0193] Figure 17 (a) shows the light distribution of the light-emitting element array of the light writing device (represented by LPH in the figure) of the first embodiment.

[0194] The figure shows the brightness of the light beam emitted from the light-emitting point of the light-emitting element in the light-emitting element array.

[0195] Here, for comparison, the light intensity curves generated by the surface-emitting laser (represented by ROS in the figure) were compared, and the results confirmed that the light intensity distribution of the light-emitting element array in the embodiment is large.

[0196] in addition, Figure 17 The light intensity distribution in (a) shows the light intensity distribution in the sub-scanning direction, but roughly the same tendency is also observed in the main scanning direction.

[0197] In addition, such as Figure 17As shown in (b), a printed sample of text at 2400 dpi was used, and the results confirmed high-resolution image reproduction. Here, as evaluation criteria, at optimal focus, the step size was 600 dpi / 2 on 2 off, and the character resolution was 4 pt. Furthermore, for comparison, a printed sample using a surface-emitting laser was used, and the printed sample from the resulting example showed greater detail.

Claims

1. A light-emitting component, comprising: The first row of light-emitting elements is composed of light-emitting elements arranged in the main scanning direction; and The second light-emitting element column consists of light-emitting elements arranged in the main scanning direction. The second light-emitting element column is arranged in the main scanning direction such that it is offset relative to the first light-emitting element column in the sub-scanning direction, and each light-emitting element in the second light-emitting element column is located between the light-emitting elements in the first light-emitting element column. The spacing between the light-emitting points of each light-emitting element in the first light-emitting element column and the light-emitting points of each light-emitting element in the second light-emitting element column in the main scanning direction is less than 1 / 2 of the spacing between the light-emitting points of each light-emitting element in the first light-emitting element column and the second light-emitting element column in the main scanning direction. The light-emitting component configures the light-emitting areas (i.e., light-emitting point areas) of each light-emitting element in the first light-emitting element column and the light-emitting areas (i.e., light-emitting point areas) of each light-emitting element in the second light-emitting element column to overlap in the main scanning direction. The overlap of the light-emitting point regions of adjacent light-emitting elements between the first and second light-emitting element columns in the main scanning direction is between 30% and 70%. The light-emitting component configures the light-emitting beam regions in the light-emitting point regions (i.e., the regions where each light-emitting element in the first light-emitting element column emits light from a location other than the surrounding non-transparent electrodes) to emit light towards the object, and the light-emitting beam regions in the light-emitting point regions (i.e., the regions where each light-emitting element in the second light-emitting element column emits light from a location other than the surrounding non-transparent electrodes) to emit light towards the object, so that there are no gaps in the main scanning direction. The overlap of the light beam regions of adjacent light-emitting elements between the first and second light-emitting element columns in the main scanning direction is between 0% and 10%.

2. The light-emitting component according to claim 1, wherein, The spacing between the light-emitting points of each light-emitting element in the first light-emitting element column and the light-emitting points of each light-emitting element in the second light-emitting element column in the sub-scanning direction is an integer multiple of the imaging line spacing N.

3. An optical writing device, comprising: The light-emitting component according to claim 1 or 2, and An imaging unit that causes light emitted from each light-emitting element of the light-emitting component to form an image on an image holding unit capable of holding a light-based image, and a light writing device that writes a light-based image into the image holding unit.

4. The optical writing device according to claim 3, wherein, The imaging unit is formed by arranging a refractive index distribution lens with a diameter greater than the difference between the sub-scanning directions of each light-emitting element in the first light-emitting element column and each light-emitting element in the second light-emitting element column in the main scanning direction.

5. The optical writing device according to claim 4, wherein, The emitted light from the first and second light-emitting element columns is incident on different positions relative to the refractive index distribution lens in the sub-scanning direction.

6. The optical writing device according to claim 5, wherein, There are multiple light-emitting element chips that include the first light-emitting element column and the second light-emitting element column. The plurality of light-emitting element chips are offset in the sub-scanning direction and the main scanning direction. The imaging unit is formed by arranging the refractive index distribution lenses in multiple adjacent columns along the main scanning direction. Light from each light-emitting element of the same light-emitting element chip is incident on a refractive index distribution lens arranged in the same column along the main scanning direction, while light from each light-emitting element of adjacent light-emitting element chips is incident on a refractive index distribution lens in a different column.

7. An image forming apparatus comprising: The optical writing apparatus according to any one of claims 3 to 6; and An image holding unit is disposed opposite to the light writing device and holds the light-based image written by the light writing device.

8. The image forming apparatus according to claim 7, wherein, When the optical writing device writes a linear image along the main scanning direction into the image holding unit using light emitted from each of the light-emitting elements in the first and second light-emitting element columns, it configures the imaging beam region corresponding to the light-emitting point adjacent in the main scanning direction to overlap.

Images