JP7060329B2 - Optical writing device and image forming device - Google Patents

Description

The present invention relates to an optical writing device and an image forming apparatus including the optical writing device.

Conventionally, a plurality of light emitting element groups including a plurality of light emitting elements (for example, LED (Light Emitting Diode) and OLED (Organic Light-Emitting Diode)) are arranged in the main scanning direction (main direction) and the sub scanning direction (secondary direction), respectively. There is known an optical writing device including a light emitting substrate and a lens array in which image forming diodes are arranged one-to-one with respect to the light emitting element group (see, for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2008-207540 Japanese Unexamined Patent Publication No. 2009-51194 Japanese Unexamined Patent Publication No. 2016-135546

By the way, when an OLED is used as a light emitting element, there is a problem that the life is shorter than when an LED is used. In order to increase the amount of light emitted while maintaining the life of the light emitting element for a long time, it is necessary to increase the area of the light emitting element. Therefore, when the OLED is used as the light emitting element, the size (diameter) of the light emitting element becomes larger than that when the LED is used. Therefore, the optical writing device and the image forming apparatus provided with the optical writing device tend to be large in size. Therefore, as a countermeasure against the increase in size of the apparatus, the size of the light emitting board and the circuit is reduced by selecting a sequential selection circuit having a regular light emitting time in the light emitting board. In this sequential selection circuit method, it is necessary to give regularity to the light emitting time, so that the arrangement of the light emitting elements in the sub-direction is restricted.

However, when the diameter of the light emitting element using the OLED is increased, the object height of the imaging lens increases in proportion to the diameter, so that not only the light emitting substrate but also the imaging lens and the lens array become large. Therefore, in order to prevent the optical writing device and the image forming device from becoming large in size, it is necessary to reduce the size of the lens array as well. Although it is conceivable to reduce the height of the object and make the imaging lens smaller by reducing the number of light emitting elements facing one imaging lens, the number of imaging lenses required for image formation increases. Therefore, it did not lead to the miniaturization of the lens array.

An object of the present invention is to provide an optical writing device capable of realizing miniaturization of the device and an image forming device including the optical writing device.

The invention according to claim 1 has been made in order to achieve the above object.
A light emitting board in which a plurality of light emitting element groups in which a plurality of light emitting elements are grouped are arranged, and a light emitting board.
A lens array including a plurality of imaging lenses and condensing the light emitted from the light emitting element on an image carrier, and a lens array.
In an optical writing device equipped with
The light emitting element is an OLED.
In the light emitting element group, the light emitting elements are arranged two-dimensionally in the main scanning direction and the sub scanning direction.
The light emitting elements in the light emitting element group are arranged at equal intervals in the main scanning direction when the light emitting element is projected on a straight line in the main scanning direction.
Each of the light emitting elements is arranged so as to face the corresponding imaging lens.
The light emitting elements in the light emitting element group are grouped as channels for each light emitting timing .
The centers of gravity of the light emitting elements in the channel are aligned on a straight line parallel to the main scanning direction.
When the straight line connecting the centers of gravity of the light emitting elements in the channel is defined as the center of gravity line, the interval of the adjacent center of gravity lines in the sub-scanning direction is an integral multiple of the interval determined by the resolution in the sub-scanning direction of the imaging lens. It is decided to divide by the magnification,
Of the light emitting elements in the light emitting element group, the two light emitting elements most distant in the main scanning direction are designated as the first light emitting element and the second light emitting element, respectively, and the center of gravity of the imaging lens is projected onto the light emitting substrate. When the point is the center of gravity of the lens,
The first light emitting element or the second light emitting element is arranged at a position farthest from the center of gravity of the lens among the light emitting elements in the light emitting element group.
The number of channels in the light emitting element group is 4 or 5, and the number of channels is 4.
The first light emitting element and the second light emitting element are arranged in a channel having an odd number of light emitting elements, which is closest to the center of gravity of the lens among the channels.
As the channel moves away from the center of gravity of the lens, the number of light emitting elements in the channel decreases.

The invention according to claim 2 is the optical writing apparatus according to claim 1.
The light emitting element is an area light source and is
When the straight line passing through the lens center of gravity point and parallel to the main scanning direction is defined as the lens center of gravity line, and the distance from the center of gravity of the light emitting element to the end of the light emitting region of the light emitting element in the sub scanning direction is defined as the light emitting distance.
The distance between the center of gravity line of the channel including the first light emitting element and the second light emitting element and the center of gravity line of the lens is shorter than the light emitting distance.

The invention according to claim 3 is the optical writing apparatus according to claim 2.
The center of gravity of the channel including the first light emitting element and the second light emitting element coincides with the center of gravity of the lens.

The invention according to claim 4 is the optical writing apparatus according to any one of claims 1 to 3.
The number of channels in the light emitting element group is 5 .

The invention according to claim 5 is
In the image forming apparatus
With the image carrier,
The charging part that charges the image carrier and
The optical writing device according to any one of claims 1 to 4 , wherein an electrostatic latent image is formed on the image carrier by irradiating the image carrier charged by the charged portion with light. When,
A developing unit that visualizes the electrostatic latent image into an image by the developing agent by supplying a developing agent to the image carrier irradiated with light.
A transfer unit that transfers the image produced by the developer onto paper, and
A fixing section for fixing the image of the developer transferred by the transfer section to the paper, and a fixing section.
It is characterized by having.

According to the present invention, it is possible to realize miniaturization of the device.

It is a figure which shows the schematic structure of the image forming apparatus which concerns on this embodiment. It is a side view which shows the structure of an optical writing apparatus. It is a top view which shows the structure of a light emitting substrate. It is a top view which shows the structure of a lens array. It is a figure which shows an example of the arrangement pattern of the light emitting element in the conventional light emitting element group. It is a figure which shows an example of the timing chart explaining the arrangement pattern of the light emitting element in the light emitting element group of this embodiment, and the light emitting timing of each channel. It is a figure which shows the relationship between the object height of the imaging lens and the size of the lens array in the sub-direction in the prior art and the embodiment. It is a figure which shows the arrangement example (Example 1) of a light emitting element. It is a figure which shows the arrangement example (Example 2) of a light emitting element. It is a figure which shows the arrangement example (Example 3) of a light emitting element. It is a figure which shows the arrangement example (Example 4) of a light emitting element. It is a figure which shows the arrangement example (Example 5) of a light emitting element. It is a figure which shows the arrangement example (Example 6) of a light emitting element. It is a figure which shows the arrangement example (Example 7) of a light emitting element. It is a figure which shows the arrangement example (Example 8) of a light emitting element. It is a figure which shows the arrangement example (Example 9) of a light emitting element. It is a figure which shows the arrangement example (Example 10) of a light emitting element. It is a figure which shows the arrangement example (Example 11) of a light emitting element. It is a figure which shows the arrangement example (Example 12) of a light emitting element.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Structure of image forming apparatus]
The image forming apparatus 1000 according to the present embodiment is used as, for example, a printer, a digital copying machine, or the like, and as shown in FIG. 1, a plurality of optical writing devices provided for each of cyan, magenta, yellow, and black colors. The 100, the photoconductor (image carrier) 200 such as a photoconductor drum provided corresponding to the optical writing device 100, the charging unit 210 for charging the photoconductor 200, and the photoconductor 200 irradiated with light. A developing unit 220 that visualizes an electrostatic latent image into an image produced by the developing agent by supplying a developing agent, an intermediate transfer belt 300, and a transfer roller (transfer unit) 400 that transfers an image produced by the developing agent to paper P. The fixing unit 500 for fixing the image of the developer transferred by the transfer roller 400 to the paper P is provided.

The image forming apparatus 1000 forms a toner image with the photoconductor 200 exposed to the light emitted from the optical writing apparatus 100, and transfers the toner image onto the intermediate transfer belt 300. Next, the image forming apparatus 1000 presses the toner image transferred to the intermediate transfer belt 300 against the paper P by the transfer roller 400 to transfer the toner image, and heats and pressurizes the paper P by the fixing portion 500 to obtain the toner image. Is fixed on the paper P. Then, the image forming apparatus 1000 performs the image forming process by transporting the paper P by a paper ejection roller (not shown) or the like and ejecting the paper to a tray (not shown).

As shown in FIGS. 1 to 4, the optical writing device 100 forms an electrostatic latent image on the photoconductor 200 by irradiating the photoconductor 200 charged by the charging unit 210 with light L. It is a device. The optical writing device 100 places a light emitting substrate 11 in which a plurality of light emitting element groups 112 in which a plurality of light emitting elements 111 for emitting light L are grouped are arranged, and light L emitted from the plurality of light emitting elements 111 on the photoconductor 200. It is configured to include a lens array 12 for condensing light.

In the following description, the longitudinal direction (main direction) of the light emitting substrate 11 and the lens array 12 shown in FIGS. 2 to 4 and the like are orthogonal to the X direction, and the lateral direction (secondary direction) is orthogonal to the Y direction, the X direction, and the Y direction. The direction is the Z direction. Further, in the optical writing apparatus 100 shown in FIGS. 2 to 4, the side on which the lens array 12 is arranged is the upper side, and the side on which the light emitting substrate 11 is arranged is the lower side. In the present embodiment, the light L is emitted upward in the Z direction from the light emitting substrate 11 of the optical writing device 100. That is, the Z direction coincides with the optical axis direction of the light L.

As shown in FIG. 3, the light emitting substrate 11 is formed in a substantially rectangular shape, and a plurality of light emitting element groups 112 are arranged in a plurality of rows (here, three rows) in a substantially straight line along the longitudinal direction (X direction). Have been placed. The plurality of light emitting element groups 112 are arranged so as to be slightly shifted in the X direction so as not to overlap in the lateral direction (Y direction) of the light emitting substrate 11. In the present embodiment, a plurality of light emitting element groups 112 are arranged in a plurality of rows along the Y direction, but the present invention is not limited to this, and for example, a plurality of light emitting element groups 112 are arranged in one row. It may be configured in. Further, in the present embodiment, an organic EL (OLED) is used as the light emitting element 111, and the light emitting substrate 11 is made of glass having a small coefficient of linear expansion (for example, non-alkali glass). Further, the light emitting element 111 is an area light source.

As shown in FIGS. 2 to 4, the lens array 12 is arranged between the light emitting substrate 11 and the photoconductor 200, and a plurality of imaging lenses 121 face a plurality of light emitting element groups 112 on the light emitting substrate 11. They are arranged side by side at positions, that is, at positions where they overlap in the optical axis direction (Z direction) (see FIGS. 3 and 4). The reference numeral 113 shown in FIG. 3 indicates a “projecting portion” corresponding to the contour when a plurality of imaging lenses 121 formed in a circular shape are projected onto the light emitting substrate 11, and the light emitting element group 112. Each is contained within the corresponding projection 113. Therefore, referring to FIG. 3, it can be seen that the plurality of imaging lenses 121 are arranged side by side at positions facing the plurality of light emitting element groups 112. That is, each of the light emitting element groups 112 is arranged so as to face the corresponding imaging lens 121. Each of the plurality of imaging lenses 121 is formed so that the refractive index on the central axis, that is, the optical axis is low, and the refractive index increases as the distance from the central axis increases. The luminous flux emitted from the plurality of light emitting elements 111 of the light emitting substrate 11 passes through the plurality of imaging lenses 121 of the lens array 12 and is imaged as a minute spot on the surface of the photoconductor 200.

[Arrangement pattern of light emitting elements]
FIG. 5 shows an example of the arrangement pattern of the light emitting element 111A in the conventional light emitting element group 112A. Further, FIG. 6A shows an example of the arrangement pattern of the light emitting element 111 in the light emitting element group 112 of the present embodiment. Note that FIG. 6B is an enlarged view of the first light emitting element P1 shown in FIG. 6A.
As shown in FIG. 5, in the light emitting element group 112A, the light emitting elements 111A are arranged two-dimensionally in the X direction (main direction) and the Y direction (secondary direction). In the example shown in FIG. 5, the light emitting elements 111A are regularly arranged in both the main direction and the sub direction. Further, the light emitting element 111A is arranged so that the interval in the main direction and the interval in the sub direction are substantially equal to each other.
On the other hand, also in the example shown in FIG. 6A, in the light emitting element group 112, the light emitting elements 111 are arranged two-dimensionally in the main direction and the sub direction, and the light emitting element 111 is arranged in the main direction and the sub direction. Both are arranged regularly. However, unlike the light emitting element 111A shown in FIG. 5, the light emitting element 111 is arranged so that the interval in the main direction and the interval in the sub direction are different. Specifically, the light emitting element 111 is arranged so that the interval in the sub-direction is narrower than the interval in the main direction. Further, the light emitting elements 111 in the light emitting element group 112 are arranged at equal intervals in the main direction when the light emitting element 111 is projected onto the main line (straight line in the main direction).

Further, FIG. 6A further shows five channels (Ch1 to Ch5) and a timing chart for explaining the light emission timing of each channel. Here, the channel is a group of the light emitting elements 111 in the light emitting element group 112 according to the light emitting time (light emitting timing).
In the example shown in FIG. 6A, the light is regularly emitted in the order of Ch1 to Ch5. That is, in the present embodiment, the light emitting elements 111 are regularly arranged in the subdirection, and the sequential selection circuit having regular light emission time can be selected, so that the size of the circuit can be reduced and the light emitting substrate can be reduced. The size of 11 has been reduced.

Further, the centers of gravity of the light emitting elements 111 in each channel (Ch1 to Ch5) are arranged on a straight line (center of gravity line) parallel to the main direction. As a result, the spot positions on the photoconductor 200 formed by the imaging lens 121 are also aligned in a straight line, so that the image quality can be improved.
Further, the distance between the adjacent center of gravity lines in the sub-direction, that is, the distance between the adjacent channels in the sub-direction is determined by the resolution in the sub-direction and an integral multiple of the magnification of the imaging lens 121. For example, when the sub-direction resolution of the image is 1200 dpi and the magnification of the imaging lens 121 is 1 times, the distance between the adjacent center-of-gravity lines in the sub-direction is an integral multiple of 21.2 um.

Here, the two light emitting elements 111 that are farthest from each other in the main direction among the light emitting elements 111 in the light emitting element group 112 are referred to as a first light emitting element P1 and a second light emitting element P2, respectively. If the first light emitting element P1 is arranged at a position farther from the "lens center of gravity point C1" than the second light emitting element P2, the object heights of the imaging lens 121 are "lens center of gravity point C1" and "first. It becomes equal to the interval of the center of gravity point C2 of the light emitting element P1. The “lens center of gravity point C1” is a point where the center of gravity of the imaging lens 121 is projected onto the light emitting substrate 11.
The object height R of the imaging lens 121 has the x-axis in the main direction, the y-axis in the sub-direction, the coordinates of the center of gravity point C1 of the lens (x ₀ , y ₀ ), and the coordinates of the center of gravity point C2 of the first light emitting element P1 (x 0, y 0). When x ₁ , y ₁ ), it can be expressed by the equation (1).

Here, assuming that the coordinates of the center of gravity point C1 of the lens are the origin (0, 0), the object height R can be obtained only from the coordinates (x ₁ , y ₁ ) of the center of gravity point C2 of the first light emitting element P1. Therefore, it can be seen that in order to narrow the object height R, the values of x ₁ and y ₁ should be brought close to 0.
By the way, since the position x ₁ in the main direction of the center of gravity point C2 of the first light emitting element P1 is determined by the number of light emitting elements and the resolution in the main direction, there is no degree of freedom in the arrangement of the first light emitting element P1 in the main direction. Therefore, in the present invention, the condition for further narrowing the object height R of the imaging lens 121 is to arrange the light emitting element 111 so that the position y1 in the subdirection of the center of gravity point C2 of the _first light emitting element P1 approaches 0. That is.

In the example shown in FIG. 6A, the first light emitting element P1 and the second light emitting element P2 are the channels closest to the lens center of gravity point C1 among all the channels (Ch1 to Ch5) (Ch3 in FIG. 6A). It is located inside. That is, the first light emitting element P1 and the second light emitting element P2 are arranged in the channel whose position in the subdirection is closest to 0 among all the channels. As a result, the position y ₁ in the sub direction of the center of gravity point C2 of the first light emitting element P1 (the same applies to the position in the sub direction of the center of gravity of the second light emitting element P2) can be brought close to 0, and as a result, the imaging lens can be obtained. The object height R of 121 can be narrowed. Therefore, the sizes of the imaging lens 121 and the lens array 12 can also be reduced in proportion to the object height R of the imaging lens 121.

FIG. 7 shows the relationship between the object height R of the imaging lens 121 and the size of the lens array 12 in the subdirection in the conventional example (see FIG. 5) and the embodiment (see FIG. 6A).
As shown in FIG. 7, in the embodiment, it can be seen that the object height R and the size of the lens array 12 in the sub-direction are smaller than those of the conventional example.

[Example]
Next, an arrangement example (Examples 1 to 12) of the light emitting element 111 in the present invention will be described with reference to FIGS. 8 to 19 and Table I. 8 to 19 show an arrangement example (Examples 1 to 12) of the light emitting element 111. Table I also shows the placement parameters of Examples 1 to 12.

In Table I, "Ch number" is the number of channels in the light emitting element group 112. The “channel N in which P1 and P2 are present” is a channel in which the first light emitting element P1 and the second light emitting element P2 are arranged among the channels in the light emitting element group 112. The "number of light emitting elements in the channel" is the number of light emitting elements 111 in each channel and the total number of light emitting elements 111 in the light emitting element group 112. "Main direction spacing of light emitting elements in any channel" indicates whether the spacing (in the main direction) of the light emitting elements 111 is equal or uneven when the arbitrary channel is viewed from the subdirection. "Agreement between the channel N and the center of gravity of the lens" indicates whether or not the channel N and the center of gravity of the lens C1 overlap. The "number of light emitting elements in the channel N" indicates whether the number of light emitting elements 111 in the channel N is an even number or an odd number. If the "number of light emitting elements in the channel N" is an even number, the lens center of gravity point C1 and any of the light emitting elements 111 in the channel N do not overlap, and the "number of light emitting elements in the channel N" is odd. If so, the lens center of gravity point C1 and any of the light emitting elements 111 in the channel N will overlap.

Here, the Ch number (the number of channels in the light emitting element group 112) is more preferably an odd number as in the examples shown in FIGS. 8 to 15 (Examples 1 to 8). This is because it is possible to arrange more light emitting elements 111 while minimizing the object height R of the imaging lens 121. If the number of light emitting elements facing one imaging lens 121 is increased, the number of imaging lenses in the entire lens array 12 can be reduced by that amount. As a result, the optical writing device 100 and the image forming apparatus 1000 are used. Can be miniaturized.
The number of Chs (the number of channels in the light emitting element group 112) and the total number of light emitting elements 111 in the light emitting element group 112 are the two light emitting elements 111 (first light emitting element P1 and second light emitting element P1) farthest from each other in the main direction. As long as P2) is the maximum object height, it can be freely set.

In the examples shown in FIGS. 8 to 12 (Examples 1 to 5), when the number of light emitting elements in each channel is the same, the arrangement of the light emitting elements 111 other than the first light emitting element P1 and the second light emitting element P2 is arranged. Patterns with different regularities are shown. In this case, since the same effect can be obtained in any of the examples, the arrangement pattern is determined based on the wiring pattern, the formation conditions of the light source in the light emitting element 111, and the like.

In the example shown in FIG. 12 (Example 5), the number of light emitting elements in the channel is reduced as the channel moves away from the lens center of gravity point C1. In this way, by reducing the number of light emitting elements in the channel farther from the center of gravity point C1 of the lens, the arrangement of the light emitting elements 111 arranged at the end in the main direction in the light emitting element group 112 is formed into an outer circular shape of the imaging lens 121. Since it can be imitated, the effective range of the imaging lens 121 can be fully utilized.

In the examples shown in FIGS. 8 to 12 and 14 to 18 (Examples 1 to 5, 7 to 11), a case where the channel N and the lens center of gravity point C1 coincide with each other is shown. Here, the straight line parallel to the main direction passing through the center of gravity point C1 of the lens is defined as the "center of gravity line of the lens", and the distance from the center of gravity of the light emitting element 111 to the end of the light emitting region of the light emitting element 111 in the sub direction is the "light emitting distance H". (See FIG. 6 (b)) ”. In this case, the distance between the center of gravity of the channel including the first light emitting element P1 and the center of gravity of the lens (y = 0) is 0. That is, the position y1 in the subdirection of the center of gravity point C2 of the _first light emitting element P1 is arranged so as to be 0. In this way, by setting the position y1 in the subdirection of the center of gravity point C2 of the _first light emitting element P1 to 0, it is possible to minimize the object height R of the imaging lens 121.
On the other hand, the examples shown in FIGS. 13 and 19 (Examples 6 and 12) show a case where the channel N and the lens center of gravity point C1 do not match. As described above, even if a deviation occurs between the channel N and the lens center of gravity point C1 due to manufacturing variation, assembly error, design convenience, etc., the effect of suppressing the object height R of the imaging lens 121 is suppressed. Can be obtained.

In the examples shown in FIGS. 16 to 18 (Examples 9 to 11), the Ch number (the number of channels in the light emitting element group 112) is an even number, and the channel N and the lens center of gravity point C1 coincide with each other. Is shown. In this case, the number of channels on the sub-direction plus side (for example, in the direction of Ch1) and the number of channels on the sub-direction minus side (for example, in the direction of Ch4) about the lens center of gravity point C1 are not equal, so that the symmetry is broken. It is possible to obtain the effect of suppressing the maximum object height.

In the examples shown in FIGS. 8 to 11, 13, 14, and 16 (Examples 1 to 4, 6, 7, and 9), the light emitting elements 111 in each channel are arranged at equal intervals in the principal direction. Shows the case. In this case, since the space required for passing the electrical wiring to each light emitting element 111 can be sufficiently secured, the wiring work can be easily performed, and the light emitting substrate 11 can be easily molded. be able to.

As described above, according to the optical writing device 100 of the image forming apparatus 1000 according to the present embodiment, in the light emitting element group 112, the light emitting elements 111 are arranged two-dimensionally in the main scanning direction and the sub-scanning direction. Have been placed. The light emitting elements 111 in the light emitting element group 112 are arranged at equal intervals in the main scanning direction when the light emitting element 111 is projected onto the main line. Each of the light emitting element groups 112 is arranged so as to face the corresponding imaging lens 121. The light emitting elements 111 in the light emitting element group 112 are grouped as channels for each light emitting time. The centers of gravity of the light emitting elements 111 in the channel are aligned on a straight line parallel to the main scanning direction. When the straight line connecting the centers of gravity of the light emitting elements 111 in the channel is defined as the center of gravity line, the distance between the adjacent center of gravity lines in the sub-scanning direction is determined based on the resolution in the sub-scanning direction and the magnification of the imaging lens 121. Of the light emitting elements 111 in the light emitting element group 112, the two light emitting elements 111 that are farthest from each other in the main scanning direction are designated as the first light emitting element P1 and the second light emitting element P2, respectively, and the center of gravity of the imaging lens 121 is on the light emitting substrate 11. When the point projected on the lens is the center of gravity of the lens, the first light emitting element P1 or the second light emitting element P2 is arranged at a position farthest from the center of gravity of the lens among the light emitting elements 111 in the light emitting element group 112. The first light emitting element P1 and the second light emitting element P2 are arranged in the channel closest to the center of gravity of the lens among the channels.
Therefore, according to the optical writing device 100 according to the present embodiment, the object height is narrowed without reducing the number of light emitting elements 111 facing one imaging lens 121 while satisfying the limitation of the sequential selection circuit method. Therefore, it is possible to reduce the size of the imaging lens 121 and the lens array 12, and it is possible to realize the miniaturization of the apparatus.

Further, according to the optical writing device 100 according to the present embodiment, the center of gravity line of the channel including the first light emitting element P1 and the second light emitting element P2 and the center of gravity line of the lens coincide with each other.
Therefore, according to the optical writing device 100 according to the present embodiment, the object height of the imaging lens 121 can be minimized, so that the sizes of the imaging lens 121 and the lens array 12 can be minimized. Therefore, the device can be made as small as possible.

Further, according to the optical writing device 100 according to the present embodiment, the number of channels in the light emitting element group 112 is an odd number.
Therefore, according to the optical writing device 100 according to the present embodiment, it is possible to arrange more light emitting elements 111 while minimizing the object height of the imaging lens 121, so that the entire lens array 12 is imaged. It is possible to reduce the number of lenses and realize the miniaturization of the device.

Further, according to the optical writing device 100 according to the present embodiment, as the channel moves away from the center of gravity of the lens, the number of light emitting elements in the channel decreases.
Therefore, according to the optical writing device 100 according to the present embodiment, the arrangement of the light emitting elements 111 arranged at the end in the main direction in the light emitting element group 112 can be made to imitate the outer peripheral circular shape of the imaging lens 121. Therefore, the effective range of the imaging lens 121 can be fully utilized.

Further, according to the optical writing device 100 according to the present embodiment, the light emitting elements 111 in the channel are arranged at equal intervals in the main scanning direction.
Therefore, according to the optical writing device 100 according to the present embodiment, it is possible to secure a sufficient interval for passing the electrical wiring to each light emitting element 111, so that the wiring work can be easily performed. This makes it possible to easily mold the light emitting substrate 11.

Although the present invention has been specifically described above based on the embodiment of the present invention, the present invention is not limited to the above embodiment and can be changed without departing from the gist thereof.

For example, the distance between the center of gravity of the channel including the first light emitting element P1 and the second light emitting element P2 and the center of gravity of the lens may be shorter than the light emitting distance H. In this case, the position y1 in the subdirection of the center of gravity point C2 of the _first light emitting element P1 is arranged so as to be shorter than the light emitting distance H. In this way, by making the position y1 in the subdirection of the center of gravity point C2 of the _first light emitting element P1 shorter than the light emitting distance H, it is possible to reduce the object height R of the imaging lens 121.

As described above, the object height R of the imaging lens 121 is increased by making the distance between the center of gravity of the channel including the first light emitting element P1 and the second light emitting element P2 and the center of gravity of the lens shorter than the light emitting distance H. Since it can be made smaller, the sizes of the imaging lens 121 and the lens array 12 can be made smaller, and the device can be miniaturized.

In addition, the detailed configuration of each device constituting the image forming apparatus and the detailed operation of each device can be appropriately changed without departing from the spirit of the present invention.

1000 Image forming device 100 Optical writing device 11 Light emitting substrate 111 Light emitting element 112 Light emitting element group 113 Projecting unit 12 Lens array 121 Imaging lens 200 Photoreceptor (image carrier)
210 Charging part 220 Developing part 300 Intermediate transfer belt 400 Transfer roller (transfer part)
500 fixing part

Claims (5)

A light emitting board in which a plurality of light emitting element groups in which a plurality of light emitting elements are grouped are arranged, and a light emitting board.
A lens array including a plurality of imaging lenses and condensing the light emitted from the light emitting element on an image carrier, and a lens array.
In an optical writing device equipped with
The light emitting element is an OLED.
In the light emitting element group, the light emitting elements are arranged two-dimensionally in the main scanning direction and the sub scanning direction.
The light emitting elements in the light emitting element group are arranged at equal intervals in the main scanning direction when the light emitting element is projected on a straight line in the main scanning direction.
Each of the light emitting elements is arranged so as to face the corresponding imaging lens.
The light emitting elements in the light emitting element group are grouped as channels for each light emitting timing .
The centers of gravity of the light emitting elements in the channel are aligned on a straight line parallel to the main scanning direction.
When the straight line connecting the centers of gravity of the light emitting elements in the channel is defined as the center of gravity line, the interval of the adjacent center of gravity lines in the sub-scanning direction is an integral multiple of the interval determined by the resolution in the sub-scanning direction of the imaging lens. It is decided to divide by the magnification,
Of the light emitting elements in the light emitting element group, the two light emitting elements most distant in the main scanning direction are designated as the first light emitting element and the second light emitting element, respectively, and the center of gravity of the imaging lens is projected onto the light emitting substrate. When the point is the center of gravity of the lens,
The first light emitting element or the second light emitting element is arranged at a position farthest from the center of gravity of the lens among the light emitting elements in the light emitting element group.
The number of channels in the light emitting element group is 4 or 5, and the number of channels is 4.
The first light emitting element and the second light emitting element are arranged in a channel having an odd number of light emitting elements, which is closest to the center of gravity of the lens among the channels.
An optical writing device, characterized in that the number of light emitting elements in the channel decreases as the channel moves away from the center of gravity of the lens. The light emitting element is an area light source and is
When the straight line passing through the lens center of gravity point and parallel to the main scanning direction is defined as the lens center of gravity line, and the distance from the center of gravity of the light emitting element to the end of the light emitting region of the light emitting element in the sub scanning direction is defined as the light emitting distance.
The optical writing device according to claim 1, wherein the distance between the center of gravity line of the channel including the first light emitting element and the second light emitting element and the center of gravity line of the lens is shorter than the light emitting distance. The optical writing device according to claim 2, wherein the center of gravity of the channel including the first light emitting element and the second light emitting element coincides with the center of gravity of the lens. The optical writing device according to any one of claims 1 to 3, wherein the number of channels in the light emitting element group is 5 . With the image carrier,
The charging part that charges the image carrier and
The optical writing device according to any one of claims 1 to 4 , wherein an electrostatic latent image is formed on the image carrier by irradiating the image carrier charged by the charged portion with light. When,
A developing unit that visualizes the electrostatic latent image into an image by the developing agent by supplying a developing agent to the image carrier irradiated with light.
A transfer unit that transfers the image produced by the developer onto paper, and
A fixing section for fixing the image of the developer transferred by the transfer section to the paper, and a fixing section.
An image forming apparatus comprising.

Images