JP7388247B2 - Manufacturing method of optical writing device, optical writing device and image forming device - Google Patents

Description

The present invention relates to a method of manufacturing an optical writing device, an optical writing device, and an image forming apparatus.

Conventionally, printers and copying machines that form images on paper are known. Image forming devices such as printers and copiers use an optical writing device to form an electrostatic latent image, create a toner image using the formed electrostatic latent image, and transfer the toner image to a fixing device. An image is formed on the paper by applying heat and pressure to fix it on the paper.

An optical writing device includes a light-emitting substrate on which a plurality of light-emitting point groups consisting of a plurality of light-emitting points (e.g., LEDs, OLEDs) are two-dimensionally arranged in a main direction and a sub-direction, and a one-to-one relationship with respect to the light-emitting point group. and a lens array unit having imaging lenses arranged to face each other.
For example, a configuration has been disclosed in which light emitting elements (light emitting points) are arranged at different positions in the optical axis direction on one light emitting substrate according to the curvature of the photoreceptor (for example, see Patent Document 1). ).
Furthermore, a configuration is disclosed in which each light emitting element (light emitting point) is arranged on a single light emitting substrate such that the number of light emitting elements stacked in adjacent light emitting element rows is different (for example, Patent Document 2 reference).

In such an optical writing device, a light beam emitted from a light emitting point usually passes through an imaging lens, and a beam is formed on the light receiving surface of the photoreceptor. At this time, since the image quality changes depending on the beam imaging state, it is important that the beam imaging state is good. For example, when a circular OLED is used as a light emitting element, the ideal beam imaging state is such that the beam diameter corresponds to "the diameter of the circle of the light emitting element" x "the magnification of the imaging optical system", and the beam shape corresponds to A flat top shape is desirable. If the lens array unit and the light emitting substrate are placed at inappropriate positions and angles, the beam will collapse, leading to deterioration in image quality. In an optical writing device, it is essential to achieve a good beam imaging state in order to obtain high image quality, so the arrangement of the photoreceptor, light emitting substrate, and lens array unit is important.

Japanese Patent Application Publication No. 2008-221707 Japanese Patent Application Publication No. 2014-172257

Normally, lens arrays used in lens array units are often manufactured by hot press molding, which results in uneven temperature distribution during molding, and the lens array, which is a molded product, has a shape close to a quadratic curve. Deflection will occur. Although this deflection of the lens array is corrected when forming the lens array into a unit, a certain degree of deflection still remains. Even if a lens array unit having residual deflection is arranged according to the designed value, a good beam imaging state cannot be obtained due to the influence of the residual deflection, resulting in a decrease in image quality.

If the light-emitting substrate is composed of one piece as in the configurations described in Patent Documents 1 and 2, the influence of residual deflection of the lens array unit can be absorbed by moving the position of the light-emitting substrate back and forth in the optical axis direction. can do. Specifically, first, a light emitting element in the light emitting substrate is caused to emit light, and a state is realized in which a beam obtained by passing through a lens array unit having residual deflection can be observed. In this state, the light emitting substrate is moved back and forth in the optical axis direction, the behavior of changes in the amount of defocus and the beam imaging state is determined, and the light emitting substrate is placed at a position where the beam diameter is near the minimum. By making such an adjustment, a good beam imaging state can be obtained even with a lens array unit that has residual deflection.

However, in recent years, a structure in which a plurality of light emitting substrates are stacked in a stepwise manner in the optical axis direction has been used, particularly due to wiring restrictions and size constraints of the light emitting substrates. In the case of a structure in which a plurality of light emitting substrates are stacked, it is necessary to move the light emitting substrates one by one back and forth in the optical axis direction in order to absorb the influence of residual deflection of the lens array unit. However, since there is no gap between the light emitting substrates in the optical axis direction, if one tries to move the light emitting substrates back and forth in the optical axis direction one by one, the light emitting substrates will collide with each other and the light emitting substrates will be damaged. Therefore, in the case of a structure in which a plurality of light emitting substrates are stacked, it is very difficult to obtain a good beam imaging state.

The present invention provides an optical lens that can improve image quality by realizing a good beam imaging state without damaging the laminated light emitting substrates even when using a lens array with residual deflection. The object of the present invention is to provide a method for manufacturing a writing device, an optical writing device, and an image forming device.

The invention according to claim 1 is made to achieve the above object,
a light-emitting substrate unit in which at least three light-emitting substrates each having a plurality of light-emitting point groups arranged in a two-dimensional array are arranged;
an imaging optical system that images the light flux emitted from the light emitting point group at different positions on the photoreceptor;
Equipped with
The imaging optical system includes:
a plurality of lens arrays having a plurality of imaging lenses arranged opposite to each of the plurality of light emitting point groups;
Aperture plate and
Equipped with
The light emitting board unit is
The at least three light emitting substrates are arranged in parallel and stacked in the optical axis direction,
The light emitting point groups of each of the at least three light emitting substrates are shifted in the secondary direction,
Each of the intervals in the optical axis direction between the adjacent light emitting substrates is not equal,
The normal line of the plane on which the light emitting point group of the light emitting substrate is arranged and the normal line to the light receiving surface of the photoreceptor are not parallel,
A method for manufacturing an optical writing device, wherein a light beam emitted from each of the light emitting points is focused on the light receiving surface of the photoreceptor,
A light beam emitted from the imaging lens facing a first light emitting substrate closest to the photoreceptor is a first light beam,
When the light beam emitted from the imaging lens facing the second light emitting substrate that is farthest from the photoreceptor is a second light beam,
a first step of shifting the entire light emitting substrate unit in the optical axis direction and adjusting the first light beam and the second light beam to be focused on the light receiving surface of the photoreceptor;
a second step of shifting the first light emitting substrate or the second light emitting substrate in the optical axis direction so that a line connecting the focal points of the light beams emitted from each of the light emitting substrates becomes a straight line;
The entire light emitting substrate unit is rotated around the center of gravity of the light emitting point group of the first light emitting substrate or the second light emitting substrate that has not been shifted in the optical axis direction in the second step, and the focus of all the light beams is a third step of adjusting the light to be focused on the light-receiving surface of the photoreceptor;
It is characterized by including.

The invention according to claim 2 is a method for manufacturing an optical writing device according to claim 1, comprising:
The aperture plate is located between the plurality of lens arrays.

The invention according to claim 3 is a method for manufacturing an optical writing device according to claim 1 or 2, comprising:
It is characterized in that the imaging magnifications of the imaging lenses of the imaging optical system are all equal.

The invention according to claim 4 provides a method for manufacturing an optical writing device according to any one of claims 1 to 3, comprising:
The imaging magnification of each of the imaging lenses of the imaging optical system is preferably 1.0 or less.

The invention according to claim 5 provides a method for manufacturing an optical writing device according to any one of claims 1 to 4, comprising:
The light emitting point is characterized in that it has Lambertian light distribution characteristics.

The invention according to claim 6 provides a method for manufacturing an optical writing device according to any one of claims 1 to 5, comprising:
The light emitting device is characterized in that a distance adjusting section capable of adjusting the distance in the optical axis direction is provided between the adjacent light emitting substrates.

The invention according to claim 7 provides a method for manufacturing an optical writing device according to any one of claims 1 to 6, comprising:
The light emitting point is characterized in that it is composed of organic EL.

The invention according to claim 8 provides a method for manufacturing an optical writing device according to any one of claims 1 to 7, comprising:
It is characterized in that the focal point of all the light beams is within a range of ±25 μm from the light receiving surface of the photoreceptor.

The invention according to claim 9 provides a method for manufacturing an optical writing device according to any one of claims 1 to 8, comprising:
BD is the width when cut by 1/e ² of the peak of the cross-sectional profile of the light beam projected onto the light-receiving surface of the photoreceptor, LD is the diameter of the light emitting point, and each of the imaging lenses of the imaging optical system is When the absolute value of the imaging magnification of is β, all the light beams projected onto the light receiving surface of the photoreceptor satisfy “BD/(LD×β)≦1.25”.

The invention according to claim 10 is
In an optical writing device,
a light-emitting substrate unit in which at least three light-emitting substrates each having a plurality of light-emitting point groups arranged in a two-dimensional array are arranged;
an imaging optical system that images the light flux emitted from the light emitting point group at different positions on the photoreceptor;
Equipped with
The imaging optical system includes:
a plurality of lens arrays having a plurality of imaging lenses arranged opposite to each of the plurality of light emitting point groups;
Aperture plate and
Equipped with
The light emitting board unit is
The at least three light emitting substrates are arranged in parallel and stacked in the optical axis direction,
The light emitting point groups of each of the at least three light emitting substrates are shifted in the secondary direction,
Each of the intervals in the optical axis direction between the adjacent light emitting substrates is not equal,
A normal to a plane on which the light-emitting point group of the light-emitting substrate is arranged and a normal to the light-receiving surface of the photoreceptor that receives the light beam are not parallel,
A light beam emitted from each of the light emitting points is focused on the light receiving surface of the photoreceptor.

The invention according to claim 11 is the optical writing device according to claim 10,
The aperture plate is located between the plurality of lens arrays.

The invention according to claim 12 is the optical writing device according to claim 10 or 11,
It is characterized in that the imaging magnifications of the imaging lenses of the imaging optical system are all equal.

The invention according to claim 13 is the optical writing device according to any one of claims 10 to 12,
The imaging magnification of each of the imaging lenses of the imaging optical system is preferably 1.0 or less.

The invention according to claim 14 is the optical writing device according to any one of claims 10 to 13,
The light emitting point is characterized in that it has Lambertian light distribution characteristics.

The invention according to claim 15 is the optical writing device according to any one of claims 10 to 14,
The light emitting device is characterized in that a distance adjusting section capable of adjusting the distance in the optical axis direction is provided between the adjacent light emitting substrates.

The invention according to claim 16 is the optical writing device according to any one of claims 10 to 15,
The light emitting point is characterized in that it is composed of organic EL.

The invention according to claim 17 is the optical writing device according to any one of claims 10 to 16,
It is characterized in that the focal point of all the light beams is within a range of ±25 μm from the light receiving surface of the photoreceptor.

The invention according to claim 18 is the optical writing device according to any one of claims 10 to 17,
BD is the width when cut by 1/e ² of the peak of the cross-sectional profile of the light beam projected onto the light-receiving surface of the photoreceptor, LD is the diameter of the light emitting point, and each of the imaging lenses of the imaging optical system is When the absolute value of the imaging magnification of is β, all the light beams projected onto the light receiving surface of the photoreceptor satisfy “BD/(LD×β)≦1.25”.

The invention according to claim 19 is
In the image forming device,
a photoreceptor;
a charging unit that charges the photoreceptor;
The optical writing device according to any one of claims 10 to 18, wherein an electrostatic latent image is formed on the photoreceptor by irradiating the photoreceptor charged by the charging unit with light;
a developing unit that supplies a developer to the photoreceptor irradiated with the light to visualize the electrostatic latent image into an image formed by the developer;
a transfer unit that transfers the image formed by the developer onto paper;
a fixing unit that fixes the developer image transferred by the transfer unit to the paper;
It is characterized by having the following.

According to the present invention, even when using a lens array with residual deflection, it is possible to achieve a good beam imaging state without damaging the stacked light emitting substrates and improve image quality.

1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a side view showing the configuration of an optical writing device in which a lens array in an ideal state without errors such as deflection is arranged. FIG. 2 is a side view showing the configuration of an optical writing device in which a lens array with errors such as deflection is arranged. FIG. 2 is a perspective view showing the configuration of a light emitting board. FIG. 3 is an optical path diagram of an imaging optical system. FIG. 3 is a diagram illustrating an initial state before adjustment at the time of manufacturing the optical writing device. 7 is a diagram illustrating a state in which the entire light emitting substrate unit is shifted in the optical axis direction from the state in FIG. 6. FIG. 8 is a diagram illustrating a state in which the light emitting substrate of the lower imaging optical system is shifted in the optical axis direction from the state in FIG. 7. FIG. FIG. 9 is a diagram illustrating a state in which the entire light emitting substrate unit is rotated from the state in FIG. 8 about an axis in the main direction. It is a figure explaining another adjustment method at the time of manufacturing an optical writing device. FIG. 3 is a diagram illustrating an example of behavior of changes in defocus amount and beam imaging state.

Embodiments of the present invention will be described in detail below with reference to the drawings.

[Configuration of image forming apparatus]
The image forming apparatus 1000 according to the present embodiment is used as a printer, a digital copying machine, etc., and as shown in FIG. 1, a plurality of optical writing devices are provided for each color of cyan, magenta, yellow, and black. 100, a photoreceptor 200 such as a photoreceptor drum provided corresponding to the optical writing device 100, a charging section 210 that charges the photoreceptor 200, and a developer supplied to the photoreceptor 200 irradiated with light. A developing section 220 that develops an electrostatic latent image into an image made of developer, an intermediate transfer belt 300, a transfer roller (transfer section) 400 that transfers an image made of developer onto paper P, and transfer roller 400. A fixing section 500 fixes the transferred developer image onto the paper P.

The image forming apparatus 1000 forms a toner image on the photoreceptor 200 exposed to light emitted from the optical writing device 100, and transfers the toner image onto the intermediate transfer belt 300. Next, the image forming apparatus 1000 presses and transfers the toner image transferred to the intermediate transfer belt 300 onto the paper P using the transfer roller 400, and heats and presses the paper P using the fixing unit 500, thereby producing the toner image. is fixed on the paper P. Then, the image forming apparatus 1000 performs image forming processing by conveying the paper P using a paper discharge roller (not shown) or the like and discharging the paper onto a tray (not shown).

[Configuration of optical writing device]
FIG. 2 shows the configuration of an optical writing device 100 in which a lens array 12 in an ideal state without errors such as deflection is arranged. Further, FIG. 3 shows the configuration of an optical writing device 100 in which a lens array 12 with errors such as deflection is arranged.
As shown in FIGS. 1 to 4, the optical writing device 100 forms an electrostatic latent image on the photoreceptor 200 by irradiating light (luminous flux) H onto the photoreceptor 200 charged by the charging unit 210. This is a device that forms The optical writing device 100 has at least three (three in this embodiment) light emitting substrates 11a to 11c each having a plurality of light emitting point groups 112 in which a plurality of light emitting points 111 that emit light H are arranged two-dimensionally. The light emitting substrate unit 11 has a light emitting substrate unit 11 , and a plurality of imaging lenses 121 are arranged to face each of the plurality of light emitting point groups 112 . A plurality of lens arrays 12 to condense light (first lens array 12A (lens array 12 closest to the light emitting point group 112 along the optical axis), second lens array 12B (lens closest to the photoreceptor 200 along the optical axis) The lens array 12) includes an aperture plate 13 disposed between the first lens array 12A and the second lens array 12B. The lens array 12 (first lens array 12A, second lens array 12B) and aperture plate 13 focus the light H emitted from the light emitting point group 112 on different positions on the photoreceptor 200 to form an inverted image. It functions as an imaging optical system of the present invention.

In the following explanation, the lateral direction (minor direction) of the light emitting substrates 11a to 11c shown in FIG. (optical axis direction of H).

As shown in FIG. 4(a), the light emitting board unit 11 includes three substantially rectangular light emitting boards 11a to 11c having different lengths in the X direction, which are arranged in parallel, and one end in the X direction is arranged in parallel. They are stacked together in the Z direction, and in each of the light emitting substrates 11a to 11c, a plurality of light emitting point groups 112 are arranged substantially in a straight line along the Y direction. That is, when the distance from the photoreceptor 200 to the light emitting point group 112 is L (see FIG. 2), there are two or more levels of the distance L in the light emitting point group 112 arranged in the X direction (in this embodiment, there are three levels). The light emitting points 112 arranged in the Y direction are arranged so that the distance L is the same. In other words, the light emitting point groups 112 of each of the light emitting substrates 11a to 11c are shifted in the X direction. The light emitting substrates 11a to 11c are made of glass with a small coefficient of linear expansion (eg, alkali-free glass). In this embodiment, the light emitting point 111 has a Lambertian light distribution characteristic (a characteristic of emitting uniform brightness at any angle) or a light distribution characteristic close to a Lambertian light distribution characteristic. Specifically, the light emitting points 111 are bottom emission type organic EL (OLED), and the light emitting points 111 are two-dimensionally arranged on the light emitting substrates 11a to 11c (see FIG. 4(b)). The diameter of each light emitting point 111 is 30 μm, and they are arranged at a pitch of 10.6 μm, which corresponds to one dot at 2400 dpi, in the Y direction. There are 26 light emitting points 111 per row, and a total of 128 light emitting points 111 are arranged in a parallelogram.

As shown in FIGS. 2 to 4, a spacer (distance adjustment section) 113 whose distance in the optical axis direction (Z direction) can be adjusted is provided between adjacent light emitting substrates 11a to 11c. In the example shown in FIG. 2, since one layer of spacers 113 is provided between adjacent light emitting substrates 11a to 11c, the distance between the light emitting substrates 11a and 11b and the distance between the light emitting substrates 11b and 11c are equal. It has become. On the other hand, in the example shown in FIG. 3, the spacer 113 is provided in one layer between the light emitting substrate 11a and the light emitting substrate 11b, and in two layers between the light emitting substrate 11b and the light emitting substrate 11c. The distance L1 is different from the distance L2 between the light emitting substrates 11b and 11c (L1<L2). That is, in the example shown in FIG. 3, the intervals in the optical axis direction between adjacent light emitting substrates 11a to 11c are not equal.
Note that the spacing adjusting section of the present invention may have any configuration as long as the spacing in the optical axis direction can be adjusted, and instead of the spacer 113, a holding holder or a thick adhesive may be used. I don't mind.

As shown in FIGS. 2 and 3, the lens array 12 is arranged between the light emitting substrate unit 11 and the photoreceptor 200, and the plurality of imaging lenses 121 are arranged to form a plurality of light emitting point groups 112 on the light emitting substrates 11a to 11c. They are arranged at positions facing each other, that is, at positions where they overlap in the optical axis direction (Z direction). That is, each of the light emitting point groups 112 is arranged to directly face the corresponding imaging lens 121. Each of the plurality of imaging lenses 121 is formed such that the refractive index is low at the central axis, that is, the optical axis, and the refractive index increases as the distance from the central axis increases. Light emitted from the plurality of light emitting points 111 of the light emitting substrates 11a to 11c 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 photoreceptor 200. The lens array 12 is composed of a glass substrate and a lens surface made of resin. In the example shown in FIGS. 2 and 3, three imaging lenses 121 are arranged in the X direction. Furthermore, in reality, the imaging lenses 121 are repeatedly arranged in the Y direction, and about 287 imaging lenses 121 are arranged in total.

The configuration of the optical writing device 100 shown in FIGS. 2 and 3 is a configuration for realizing a double-sided telecentric configuration, and even when the light emitting substrate unit 11 and the photoconductor 200 are moved back and forth in the optical axis direction, the photoconductor The in-plane focal position (focus position) of the body 200 does not change. Here, "in-plane" refers to a plane formed in the X direction and the Y direction (XY plane). Normally, when the light emitting board unit 11 is moved back and forth in the optical axis direction, the imaging position of the beam irradiated onto the photoreceptor 200 shifts in the X and Y directions, but if the configuration is telecentric on both sides, Even if the light emitting substrate unit 11 and the photoreceptor 200 move back and forth in the optical axis direction, the imaging position (X, Y) of the beam does not shift. Thereby, adjustment becomes easy and a better beam imaging state can be realized.

In an imaging optical system having a double-sided telecentric configuration, as shown in FIG. 3, if the first lens array 12A and the second lens array 12B are deflected in opposite directions, the beam will be focused at a position different from the designed position. Furthermore, since the amount of deviation of the focus in the optical axis direction differs for each imaging optical system, simply moving the light emitting board unit 11 back and forth in the optical axis direction will change the focal position of all the imaging optical systems. is not near the light-receiving surface of the photoreceptor that receives the light flux. That is, even if the focus of one imaging optical system is set near the light receiving surface of the photoreceptor, a phenomenon occurs in which the focus of the other imaging optical system is shifted. Therefore, in this embodiment, as shown in FIG. 3, the distance L1 (the distance between the light emitting substrates 11a and 11b) and L2 (the distance between the light emitting substrates 11b and 11c) between the adjacent light emitting substrates 11a to 11c is By setting different values, a state in which the entire light emitting board unit 11 is tilted is created. As a result, the light beams emitted from each of the light emitting points 112 are focused near the light receiving surface of the photoreceptor.
Here, the state in which the entire light emitting substrate unit 11 is tilted means that the normal N1 of the light emitting point group 112 and the optical axis OA of the imaging optical system are not parallel. Note that the normal N1 of the light-emitting point group 112 refers to a surface formed by connecting a plurality of light-emitting point groups 112 on the light-emitting substrates 11a to 11c where the target light-emitting point group 112 exists (a surface formed by connecting a plurality of light-emitting point groups 112 is the normal to the plane). Further, the optical axis OA of the imaging optical system is a normal line to the light receiving surface of the photoreceptor. Note that the photoreceptor 200 is assumed to be very large, and the light receiving surface is assumed to be a substantially flat surface (XY plane). That is, in this embodiment, the normal to the photoreceptor light-receiving surface is the normal to the XY plane (a line parallel to the Z direction).

FIG. 5 shows an optical path diagram of the imaging optical system (viewed from the Y direction, which is the rotation axis of the photoreceptor 200). The left side of FIG. 5 (light emitting point 111 side) is the object side, and the right side (photoreceptor 200 side) is the image side. As described above, the photoreceptor 200 is assumed to be very large, and the light receiving surface is assumed to be a substantially flat surface (XY plane). In the example shown in FIG. 5, the light emitting point groups 112 are arranged at three locations in the X direction, and there is an imaging optical system corresponding to each of the light emitting point groups 112. Each imaging optical system consists of two convex lenses (imaging lens 121). The imaging lens 121 is made by laminating resin on a glass plate 122. Each imaging lens 121 is formed on one common glass plate 122. Although not shown, a transparent flat glass plate may be disposed between the photoreceptor 200 and the imaging lens 121. The flat glass plate and the exterior cover two glass plates 122 (lens array 12) on which the imaging lens 121 is laminated, and are configured to prevent dust from adhering to the imaging lens 121. The optical axis of each imaging optical system shown in FIG. 5 is perpendicular to the light receiving surface of the photoreceptor.

As shown in FIG. 5, among the imaging optical systems, the upper imaging optical system in the X direction is referred to as an upper imaging optical system K1, the central imaging optical system in the X direction is referred to as a central imaging optical system K2, and the imaging optical system in the center in the The lower imaging optical system is referred to as a lower imaging optical system K3. In addition, in order to equalize the amount of deviation of the focal position with respect to the amount of shift and rotation of the light emitting substrates 11a to 11c in each of the imaging optical systems K1 to K3, each imaging lens 121 of each of the imaging optical systems K1 to K3 is The imaging magnification is the same. Here, the imaging magnification of each imaging lens 121 of each imaging optical system K1 to K3 is preferably 1.0 or less.

[Manufacturing method of optical writing device]
Next, a manufacturing method (adjustment method during manufacturing) of the optical writing device 100 according to this embodiment will be described with reference to FIGS. 6 to 9. 6 to 9 are side sectional views of the optical writing device 100, and (b) is the beam diameter of each imaging optical system (quadratic curve in the figure: the vertical axis is the beam diameter. FIG. 4C is a diagram showing the relationship between the length) and the amount of defocus (horizontal axis), and FIG.

First, the initial state before adjustment will be described with reference to FIG. FIG. 6 shows a case where deflection occurs in the lens array 12 due to uneven temperature distribution during molding of the lens array 12, and the deflection remains even after correction when forming the lens array 12 into a unit. In the example shown in FIG. 6, since the first lens array 12A and the second lens array 12B are deflected in opposite directions, the focal position of each imaging optical system (upper imaging The focal position F1 of the optical system K1, the focal position F2 of the central imaging optical system K2, and the focal position F3 of the lower imaging optical system K3) vary in the optical axis direction (see FIG. 6(a)). As shown in FIGS. 6(a) and 6(b), the focal position of the beam is shifted in a quadratic curve along the remaining deflection, and as a result, the image formation of all the imaging optical systems is The condition has deteriorated (see FIG. 6(c)).
Hereinafter, with reference to FIGS. 7 to 9, an adjustment procedure for improving the imaging state in all the imaging optical systems will be described. In this embodiment, it is assumed that the focus position shifts in a quadratic curve due to deflection. That is, it is assumed that the error amount is equal in the upper imaging optical system K1 and the lower imaging optical system K3 due to the deflection that is close to a quadratic curve centered on the central imaging optical system K2.

First, as shown in FIG. 7, the entire light emitting substrate unit 11 is shifted forward and backward in the optical axis direction (in FIG. 7, in a direction away from the photoreceptor 200). As a result, as shown in FIGS. 7(a) to 7(c), only the central imaging optical system K2 is out of focus, and the upper imaging optical system K1 and the lower imaging optical system K3 are in focus. produce. That is, the light beam emitted from the imaging lens 121 facing the light emitting substrate (first light emitting substrate) 11a which is closest to the photoreceptor 200 is defined as the first light beam H1, and the light beam emitted from the light emitting substrate (first light emitting substrate) which is the farthest from the photoreceptor 200 is the first light beam H1. 2) When the light beam emitted from the imaging lens 121 facing the light emitting substrate 11c is the second light beam H2, the entire light emitting substrate unit 11 is shifted in the optical axis direction, and the first light beam H1 and the second light beam H2 are exposed to light. Adjustment is made so that the light is focused on the body light-receiving surface S1 (first step).

Next, as shown in FIG. 8, either the light emitting substrate 11a of the upper imaging optical system K1 or the light emitting substrate 11c of the lower imaging optical system K3 (the light emitting substrate 11c in FIG. 8, it is shifted in the direction away from the photoreceptor 200). At this time, as shown in FIGS. 8(a) to 8(c), the light emitting substrate 11a or 11c to be shifted is shifted so that a straight line D1 is formed by connecting the focal positions F1 to F3 of all the imaging optical systems. let That is, the light emitting substrate 11a or 11c to be shifted is shifted in the optical axis direction so that the line connecting the focal points of the light beams emitted from each of the light emitting substrates 11a to 11c becomes a straight line (second step).
Note that the light-emitting substrate 11a or 11c to be shifted is shifted so that the distance from the light-emitting substrate 11b in the center becomes wider. This makes it possible to avoid collision between the light emitting substrate 11a or 11c to be shifted and the central light emitting substrate 11b, thereby preventing damage or deterioration of the light emitting element (light emitting point 111).

Finally, as shown in FIG. 9, the entire light emitting board unit 11 is rotated around the axis in the Y direction. Thereby, as shown in FIGS. 9(a) to 9(c), all the imaging optical systems can be focused on the photoreceptor light-receiving surface S1. Note that the axis in the Y direction when rotating the entire light emitting substrate unit 11 is determined when the focal position is on the light emitting substrate 11a or 11c that has not been shifted in the second step (see FIG. 8), that is, on the photoreceptor light receiving surface S1. This is the center of gravity of the light emitting point group 112 of a certain light emitting substrate 11a or 11c (the light emitting substrate 11a in FIG. 8). That is, in the second step, the entire light emitting substrate unit 11 is rotated around the center of gravity (or center) of the light emitting point group 112 of 11a or 11c, which has not been shifted in the optical axis direction, so that the focus of all the light beams is on the photoreceptor light receiving surface. Adjustment is made so that the light is focused on S1 (third step).
As described above, by performing the adjustments shown in FIGS. 6 to 9, even if the lens array 12 is bent, all the imaging optical systems can focus on the photoreceptor light receiving surface S1. Since the beams can be matched, a good beam imaging state can be achieved.

In this embodiment, as described above, in order to equalize the amount of deviation of the focal position with respect to the amount of shift and rotation of the light emitting substrates 11a to 11c in each of the imaging optical systems K1 to K3, The imaging magnifications of the imaging lenses K1 to K3 are the same for each imaging lens 121. Thereby, adjustment can be simplified to a level that can be adjusted manually.

FIG. 11 shows an example of the behavior of changes in defocus amount and beam imaging state. In the example shown in FIG. 11, the imaging magnification of each imaging lens 121 of the imaging optical system is set to 1.0.
In this embodiment, in order to obtain the desired image quality, the amount of defocus (the range in which the focal position is from the equivalent surface of the photoconductor) to be achieved by the above-described adjustment during manufacturing is determined using the following method. are doing. Specifically, the width (beam diameter) when cut at 1/e ² (13.5%) of the peak of the cross-sectional profile of the light flux (beam) projected onto the light receiving surface of the photoreceptor is defined as BD, and the light emitting point is defined as BD. When the diameter of the lens 111 is LD and the absolute value of the imaging magnification of each imaging lens 121 of the imaging optical system is β, the total luminous flux projected onto the photoreceptor light receiving surface is expressed as “BD/(LD×β )≦1.25” is determined. In the example shown in FIG. 11, the absolute value β of the imaging magnification for each imaging lens 121 of the imaging optical system is 1.0, so that the condition that “BD/LD≦1.25” is satisfied is The amount of defocus is determined.
For example, in the example shown in FIG. 11, when the defocus amount is -50 μm, BD/LD=1.43, and when the defocus amount is 50 μm, BD/LD=1.51. ” Therefore, when “the defocus amount is ±50 μm”, “BD/LD≦1.25” is not satisfied. On the other hand, "BD/LD = 1.23" when "defocus amount is -25 μm", "BD/LD = 1.04" when "defocus amount is 0 μm", and "BD/LD = 1.04" when "defocus amount is -25 μm"; Since "BD/LD=1.24" when the defocus amount is 25 μm, "BD/LD≦1.25" is satisfied when the defocus amount is in the range of ±25 μm. Therefore, it is preferable that the focal point of all the light beams be within a range of ±25 μm from the light-receiving surface of the photoreceptor. That is, in the third step of the present embodiment, "the focus of all the light beams is focused on the photoreceptor light-receiving surface S1" means that the focus of all the light beams is within a range of ±25 μm from the photoreceptor light-receiving surface. This is an expression that includes the situation where

As described above, the optical writing device 100 according to the present embodiment is a light emitting device on which at least three light emitting substrates 11a to 11c are arranged, each of which has a plurality of light emitting point groups 112 in which a plurality of light emitting points 111 are two-dimensionally arranged. It includes a substrate unit 11 and an imaging optical system that images the light beams emitted from the light emitting point group 112 at different positions on the photoreceptor 200. The imaging optical system includes a plurality of lens arrays 12 having a plurality of imaging lenses 121 arranged to face each of the plurality of light emitting point groups 112, and an aperture plate 13. In the light-emitting substrate unit 11, at least three light-emitting substrates 11a to 11c are arranged in parallel and stacked in the optical axis direction, and a light-emitting point group 112 of each of the at least three light-emitting substrates 11a to 11c is arranged as a sub-unit. The distances in the optical axis direction between adjacent light emitting substrates 11a to 11c are not equal, but are different from the normal to the plane on which the light emitting points 112 of the light emitting substrates 11a to 11c are arranged. The normal line to the light-receiving surface of the photoreceptor is not parallel, and the light beams emitted from each of the light-emitting points 112 are focused on the light-receiving surface of the photoreceptor. Further, in the method for manufacturing the optical writing device 100 according to the present embodiment, the light beam emitted from the imaging lens 121 facing the first light emitting substrate closest to the photoreceptor 200 is set as the first light beam, and the light beam emitted from the photoreceptor 200 is When the light beam emitted from the imaging lens 121 facing the second light emitting substrate which is the farthest from the second light beam is defined as the second light beam, the entire light emitting substrate unit 11 is shifted in the optical axis direction so that the first light beam and the second light beam are A first step of adjusting the light to be focused on the light-receiving surface of the photoreceptor, and adjusting the first light-emitting substrate or the second light-emitting substrate so that the line connecting the focus of the light beam emitted from each of the light-emitting substrates 11a to 11c becomes a straight line. A second step in which the light emitting substrate is shifted in the optical axis direction, and the entire light emitting substrate unit 11 is moved around the center of gravity of the light emitting point group 112 of the first light emitting substrate or the second light emitting substrate that is not shifted in the optical axis direction in the second step. and a third step of adjusting the focus of all the light beams to be focused on the light-receiving surface of the photoreceptor.
Therefore, according to the optical writing device 100 according to the present embodiment, even when using a lens array that has a shape error from a design value such as deflection due to factors such as uneven temperature distribution during molding, the laminated Since a good beam imaging state can be achieved without damaging the light emitting substrates 11a to 11c, image quality can be improved.

Further, according to the optical writing device 100 according to the present embodiment, the aperture plate 13 is present between the plurality of lens arrays 12.
Therefore, according to the optical writing device 100 according to this embodiment, it is possible to realize a double-sided telecentric configuration in the imaging optical system, so that when the light emitting substrate unit 11 is moved back and forth in the optical axis direction, the focus It is also possible to make the position move only forward and backward in the optical axis direction, and adjustment can be simplified.

Further, according to the optical writing device 100 according to the present embodiment, the imaging magnifications of the imaging lenses 121 of the imaging optical system are all equal.
Therefore, according to the optical writing device 100 according to the present embodiment, when the light emitting substrate unit 11 is moved and rotated, the amount of deviation in the focal position of each imaging optical system can be made equal, so that adjustment can be made easily. can be converted into

Further, according to the optical writing device 100 according to the present embodiment, the imaging magnification of each imaging lens 121 of the imaging optical system is 1.0 or less.
Therefore, according to the optical writing device 100 according to the present embodiment, even when a bright optical system with a shallow depth of field and requiring focal position adjustment on the order of micrometers is adopted, the amount of focal position deviation can be reduced. can be made small, making adjustment easier.

Further, according to the optical writing device 100 according to the present embodiment, the light emitting point 111 has Lambertian light distribution characteristics.
Therefore, according to the optical writing device 100 according to the present embodiment, it is possible to suppress a decrease in the amount of light when the entire light emitting substrate unit 11 is rotated, and therefore it is possible to suppress deterioration of image quality.

Furthermore, according to the optical writing device 100 according to the present embodiment, a spacer adjusting section (spacer 113) that can adjust the space in the optical axis direction is provided between the adjacent light emitting substrates 11a to 11c.
Therefore, according to the optical writing device 100 according to the present embodiment, it is possible to easily adjust the distance between the light emitting substrates 11a to 11c and improve the maintainability of the distance, so that when the light emitting point 111 is illuminated, It becomes possible to minimize changes in the interval due to heat generation, and it is possible to maintain the beam imaging state and stabilize the image quality.

Further, according to the optical writing device 100 according to the present embodiment, the light emitting point 111 is composed of an organic EL.
Therefore, according to the optical writing device 100 according to the present embodiment, Lambertian light distribution characteristics can be realized, so that deterioration in image quality can be suppressed.

Further, according to the optical writing device 100 according to the present embodiment, the focal point of all the light beams exists within a range of ±25 μm from the light-receiving surface of the photoreceptor.
Therefore, according to the optical writing device 100 according to the present embodiment, a good beam imaging state can be realized, so that image quality can be improved.

Further, according to the optical writing device 100 according to the present embodiment, the width when cut by 1/e ² of the peak of the cross-sectional profile of the light beam projected onto the light-receiving surface of the photoreceptor is defined as BD, and the width of the light-emitting point 111 is defined as BD. When the diameter is LD and the absolute value of the imaging magnification of each imaging lens 121 of the imaging optical system is β, all the light beams projected onto the photoreceptor light receiving surface are expressed as “BD/(LD×β)≦ 1.25".
Therefore, according to the optical writing device 100 according to the present embodiment, image quality can be measured using a method that is highly sensitive to changes in defocus in the flat top beam, thereby realizing a good beam imaging state. Image quality can be improved.

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

For example, in the above embodiment, as shown in FIGS. 7 to 9, first, only the central imaging optical system K2 is out of focus, and the upper imaging optical system K1 and the lower imaging optical system K3 are in focus. Shift the entire light emitting substrate unit 11 in the optical axis direction so that Finally, although the entire light emitting board unit 11 is rotated around the center of gravity of the light emitting point group 112 of the light emitting board 11a, the invention is not limited to this. For example, as shown in FIGS. 10(a) to 10(c), first, only the central imaging optical system K2 is out of focus, and the upper imaging optical system K1 and the lower imaging optical system K3 are in focus. Shifting the entire light emitting substrate unit 11 in the optical axis direction (direction approaching the photoreceptor 200) so that (see FIG. 10(a)), and then connecting the focal positions F1 to F3 of all imaging optical systems, Shift the light-emitting substrate 11a in the optical axis direction (direction approaching the photoreceptor 200) so that it forms a straight line D2 (see FIG. 10(b)), and finally shift the center of gravity of the light-emitting point group 112 of the light-emitting substrate 11c as an axis. The entire light emitting substrate unit 11 may be rotated (see FIG. 10(c)).

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

1000 Image forming apparatus 100 Optical writing device 11 Light emitting board units 11a to 11c Light emitting board 111 Light emitting points 112 Light emitting point group 113 Spacer (interval adjustment section)
12 Lens array (imaging optical system)
12A First lens array 12B Second lens array 121 Imaging lens 122 Glass plate 13 Aperture plate (imaging optical system)
200 Photoreceptor 210 Charging section 220 Developing section 300 Intermediate transfer belt 400 Transfer roller (transfer section)
500 Fixing section K1 Upper imaging optical system K2 Central imaging optical system K3 Lower imaging optical system

Claims (19)

a light-emitting substrate unit in which at least three light-emitting substrates each having a plurality of light-emitting point groups arranged in a two-dimensional array are arranged;
an imaging optical system that images the light flux emitted from the light emitting point group at different positions on the photoreceptor;
Equipped with
The imaging optical system includes:
a plurality of lens arrays having a plurality of imaging lenses arranged opposite to each of the plurality of light emitting point groups;
Aperture plate and
Equipped with
The light emitting board unit is
The at least three light emitting substrates are arranged in parallel and stacked in the optical axis direction,
The light emitting point groups of each of the at least three light emitting substrates are shifted in the secondary direction,
Each of the intervals in the optical axis direction between the adjacent light emitting substrates is not equal,
The normal line of the plane on which the light emitting point group of the light emitting substrate is arranged and the normal line to the light receiving surface of the photoreceptor are not parallel,
A method for manufacturing an optical writing device, wherein a light beam emitted from each of the light emitting points is focused on the light receiving surface of the photoreceptor,
A light beam emitted from the imaging lens facing a first light emitting substrate closest to the photoreceptor is a first light beam,
When the light beam emitted from the imaging lens facing the second light emitting substrate that is farthest from the photoreceptor is a second light beam,
a first step of shifting the entire light emitting substrate unit in the optical axis direction and adjusting the first light beam and the second light beam to be focused on the light receiving surface of the photoreceptor;
a second step of shifting the first light emitting substrate or the second light emitting substrate in the optical axis direction so that a line connecting the focal points of the light beams emitted from each of the light emitting substrates becomes a straight line;
The entire light emitting substrate unit is rotated around the center of gravity of the light emitting point group of the first light emitting substrate or the second light emitting substrate that has not been shifted in the optical axis direction in the second step, and the focus of all the light beams is a third step of adjusting the light to be focused on the light-receiving surface of the photoreceptor;
A method of manufacturing an optical writing device, comprising: 2. The method of manufacturing an optical writing device according to claim 1, wherein the aperture plate is present between the plurality of lens arrays. 3. The method of manufacturing an optical writing device according to claim 1, wherein the imaging magnifications of the imaging lenses of the imaging optical system are all equal. 4. The method for manufacturing an optical writing device according to claim 1, wherein the imaging magnification of each of the imaging lenses of the imaging optical system is 1.0 or less. 5. The method for manufacturing an optical writing device according to claim 1, wherein the light emitting point has Lambertian light distribution characteristics. The optical writing device according to any one of claims 1 to 5, characterized in that a distance adjusting section capable of adjusting the distance in the optical axis direction is provided between the adjacent light emitting substrates. Production method. 7. The method of manufacturing an optical writing device according to claim 1, wherein the light emitting point is composed of an organic EL. 8. The method for manufacturing an optical writing device according to claim 1, wherein the focal point of all the light beams is within a range of ±25 μm from the light receiving surface of the photoreceptor. BD is the width when cut by 1/e ² of the peak of the cross-sectional profile of the light beam projected onto the light-receiving surface of the photoreceptor, LD is the diameter of the light emitting point, and each of the imaging lenses of the imaging optical system is 2. All the light beams projected onto the photoreceptor light-receiving surface satisfy "BD/(LD×β)≦1.25", where β is the absolute value of the imaging magnification of 9. A method for manufacturing an optical writing device according to any one of 1 to 8. a light-emitting substrate unit in which at least three light-emitting substrates each having a plurality of light-emitting point groups arranged in a two-dimensional array are arranged;
an imaging optical system that images the light flux emitted from the light emitting point group at different positions on the photoreceptor;
Equipped with
The imaging optical system includes:
a plurality of lens arrays having a plurality of imaging lenses arranged opposite to each of the plurality of light emitting point groups;
Aperture plate and
Equipped with
The light emitting board unit is
The at least three light emitting substrates are arranged in parallel and stacked in the optical axis direction,
The light emitting point groups of each of the at least three light emitting substrates are shifted in the secondary direction,
Each of the intervals in the optical axis direction between the adjacent light emitting substrates is not equal,
A normal to a plane on which the light-emitting point group of the light-emitting substrate is arranged and a normal to the light-receiving surface of the photoreceptor that receives the light beam are not parallel,
An optical writing device characterized in that a luminous flux emitted from each of the light emitting points is focused on the light receiving surface of the photoreceptor. The optical writing device according to claim 10, wherein the aperture plate is present between the plurality of lens arrays. The optical writing device according to claim 10 or 11, wherein the imaging magnifications of the imaging lenses of the imaging optical system are all equal. The optical writing device according to claim 10, wherein the imaging magnification of each of the imaging lenses of the imaging optical system is 1.0 or less. The optical writing device according to claim 10, wherein the light emitting point has Lambertian light distribution characteristics. The optical writing device according to any one of claims 10 to 14, characterized in that a distance adjusting section capable of adjusting a distance in the optical axis direction is provided between the adjacent light emitting substrates. The optical writing device according to any one of claims 10 to 15, wherein the light emitting point is composed of an organic EL. The optical writing device according to any one of claims 10 to 16, wherein the focal point of all the light beams is within a range of ±25 μm from the light receiving surface of the photoreceptor. BD is the width when cut by 1/e ² of the peak of the cross-sectional profile of the light beam projected onto the light-receiving surface of the photoreceptor, LD is the diameter of the light emitting point, and each of the imaging lenses of the imaging optical system is 2. All the light beams projected onto the photoreceptor light-receiving surface satisfy "BD/(LD×β)≦1.25", where β is the absolute value of the imaging magnification of 18. The optical writing device according to any one of items 10 to 17. a photoreceptor;
a charging unit that charges the photoreceptor;
The optical writing device according to any one of claims 10 to 18, wherein an electrostatic latent image is formed on the photoreceptor by irradiating the photoreceptor charged by the charging unit with light;
a developing unit that supplies a developer to the photoreceptor irradiated with the light to visualize the electrostatic latent image into an image formed by the developer;
a transfer unit that transfers the image formed by the developer onto paper;
a fixing unit that fixes the developer image transferred by the transfer unit to the paper;
An image forming apparatus comprising:

Images