JPH09185226A - Image forming device and exposure condition setting method for optical mudulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an optical modulator compact and to manufacture it with excellent yield by a present semiconductor technology by shortening the whole length of respective element rows in comparison with such conventional constitution that the required number of grating light valves(GLV) is arranged in one element row. SOLUTION: The GLV element is used as the optical modulator and the required number of GLVs is divided into the CLV element rows 38a and 38b. Besides, an optical unit 10 is designed so that light beams 36a and 36b projected on the surface 35 of a photoreceptor drum by the respective rows 38a and 38b are successively arranged in the longitudinal direction thereof by mutually superposing the end part thereof. By a control part, the turning-on timing of the rows 38a and 38b are deviated so that the projected light beams 36a and 36b of the respective element rows are arrayed on a straight line on the photoreceptor drum based on the positional deviation of the light beams 36a and 36b in the moving direction of the photoreceptor drum and the mutual positional relation thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an optical modulator such as an optical printer or a copying machine.

[0002]

2. Description of the Related Art Today, an optical printer represented by a laser printer using an electrophotographic system is widely used as a personal computer or a network printer, and is also widely used as a digital copy printer or a color copy printer. It is called an optical printer because a pixel unit forming a character or an image is written and controlled by the on / off control of the optical power. A laser diode or an LED (light emitting diode) array is generally used for on / off control of optical power.

A writing optical system of a laser printer is composed of a combination of a laser diode and a polygon scanner and has a resolution of 600 DPI (Dot Per Inc).
h), 40 PPM (Pag in A4 / Letter size)
Widely used for low / medium speed machines up to e Per Minutes).

However, in response to the recent demand for high-speed printing and high-quality printing using halftone, the limitation of laser switching speed and the limitation of high-speed rotating polygon scanner technology have become problems. A writing optical system using an LED array can be expected to have high speed because of parallel exposure, but there is a problem in uniformity of individual LED emission brightness.

However, recently, a new optical modulator having a possibility of solving the above-mentioned problems has been announced for a display (US Patent No. 5,311,3).
60, and Solid State Sensors
and Actuators Workshop, Hil
ton Head Island, SC, June 13
-16, 1994).

This is a grating light valve (G
ratig Light Valve: GLV
(Abbreviated as) element, which is a micromachined phase diffraction grating that utilizes diffraction of light. By using this GLV element, on / off control of light can be electrically controlled, and it can be used as a digital optical modulator in place of the conventional rotary polygon scanner.

The structure and operating principle of the GLV element will be described with reference to FIGS. 4 to 6 which are explanatory views of the present invention. FIG. 4 is a perspective view of one GLV element, and FIG.
FIG. 6 is a diagram showing the operating principle.

As shown in FIG. 4, in the GLV element 20, a microbridge 22 integrally molded with a frame 24 is arranged on a base 21 via a spacer 23 between the frame 24 and the base 21. With the above structure, a gap having the same thickness as the spacer 23 is formed between the upper surface of the base 21 and the microbridge 22, and the two are not in contact with each other. The thickness of the void determined by the spacer 23 and the thickness of the microbridge 22 are both determined in advance by the wavelength of the light source used, and are formed to be λ / 4 nm, respectively, where the emission wavelength of the light source used is λnm. Such a GLV device 2
0 can be manufactured by a fine semiconductor manufacturing technique (the manufacturing method is described in detail in the above-mentioned document).

The operation of the GLV element 20 is controlled by turning on and off the voltage applied between the microbridge 22 and the substrate 21, and when the off control (hereinafter, turning off is used synonymously) is shown in FIG. The x-section of the GLV device 20 in FIG.
The y cross section is shown in FIG. 6, and FIG. 6A shows the x of the GLV element 20 at the time of ON control (hereinafter, lighting is used synonymously).
A cross section is shown in FIG.

As shown in FIGS. 5 (a) and 5 (b), when the GLV element 20 is turned off, the microbridge 22 is separated from the substrate 21 by λ.
When the light is incident in this state, the total optical path difference of each reflected light reflected by the microbridge 22 and the base 21 is equal to the wavelength of the incident light, and the light is incident as a diffraction grating plane mirror. Reflects light.

On the other hand, as shown in FIGS. 6A and 6B, GL
When the V element 20 is turned on, the micro bridge 22 is connected to the base 21.
When the light enters in this state, the total optical path difference of each reflected light reflected by the microbridge 22 and the base 21 becomes a half wavelength (λ / 2),
The reflected lights interfere with each other to cancel each other and cause diffraction.

Further, as a condition for realizing such a mechanical operation, the longitudinal dimension of the microbridge 22, the tensile stress, etc. are determined in consideration of the operation speed, the resilience and the like. According to the above document, the dimension y0 of the diffraction effective region in the longitudinal direction in the microbridge 22 shown in FIG.
It is described that a response of 20 nsec is obtained when is 20 μm. However, the size of one GLV element at this time also includes the dimensions of y1 and y2 which are diffraction ineffective regions,
If the frame 24 is included, it becomes about 25 μm. Further, the dimension in the direction orthogonal to the longitudinal direction of the microbridge 22, that is, the width x0 of the microbridge 22, is defined by the wavelength of light, the incident angle,
It is determined by the equation (1) described below based on the diffraction angle, and is usually 0.
5 to 2 μm.

Next, the relationship among the wavelength of light, the incident angle, and the diffraction angle will be described with reference to FIGS. 15A and 15B in terms of the overall configuration including the optical system. However, FIG. 7B is a simplified illustration of FIG.

The light from the monochromatic light source unit 50 is collimated by the collimator lens 51 and incident on the GLV optical modulator 52 at an incident angle θ _i . In the GLV optical modulator 52, a plurality of GLV elements 20 shown in FIG. 4 are arranged in a row corresponding to the width direction of the photosensitive drum 55, and a GLV element row 52a.
Is provided, and if each GLV element of the GLV element array 52a is in the ON state, it goes out at the diffraction angle θ _d , and the slit 53
Through the projection lens 54 and the photoconductor drum 5
The light hits 5. At this time, if the wavelength of light is λ nm, the following relational expression holds.

Sin θ _i −sin θ _d = λ / r (1) Here, r (nm) is the width x0 of the microbridges 22 and is equal to the interval between the microbridges 22.
In FIGS. 15A and 15B, the incident angle θ _i is selected so that the diffraction angle θ _d becomes 0 °.

On the other hand, each GL in the GLV element array 52a
When the V element is in the off state, the incident light has the same θ as the incident angle.
_Since it exits at _i , it cannot pass through the slit 53 and does not reach the photosensitive drum 55.

In this manner, each GLV element 20 of the GLV element row 52a corresponding to each pixel unit on the surface 55a of the photosensitive drum 55 is electrically turned on / off (lighting-off). As a result, light can be modulated at high speed in place of the conventional rotating polygon scanner.

[0018]

However, the GLV device disclosed in the above publication has not been sufficiently studied in the case of being applied as a writing device of an optical printer, so that the GLV device is used as a writing device of an optical printer.
When the device is applied, there are some problems.

As one of them, when it is used as a writing device of an optical printer and mounted on an optical printer as a GLV optical modulator, it is large as an optical modulator of the optical printer.
In addition, the manufacturing yield is low. That is, the publication does not describe the arrangement of GLV elements when the optical modulator of the optical printer is configured by the GLV elements. Therefore, when the required number of GLV elements are arranged in a line and used in an optical printer as an optical modulator in place of the rotating polygon scanner, and the recording width is covered by only one GLV element row, the length of the GLV element row is reduced. It becomes very large, and the optical modulator itself becomes large.

To give concrete numerical values, for example, assuming that the maximum recording width is letter size (8.5 × 11 inches) and the resolution is 600 DPI, 8.5 × 600 = 5100 pixels are required, 5,100 GLV elements are required. When 5100 GLV elements each having a size of 25 μm are arranged, the length becomes about 128 mm, which is large, and it is not possible to make a GLV element array of this length with the current semiconductor technology with a good yield. extremely difficult.

[0021]

In order to solve the above-mentioned problems, an image forming apparatus according to claim 1 of the present invention modulates irradiation light from a light source with an optical modulator to form an image on the image carrier. In an image forming apparatus that has an optical unit for projecting, visualizes an electrostatic latent image formed on the image carrier by projection light from the optical unit, and then transfers the electrostatic latent image to a transfer material and discharges the image, The modulator has a plurality of element rows in which a plurality of grating light valve elements are arranged side by side, and the optical section is an element composed of a plurality of element projection lights projected on the image carrier by each of these element rows. The column projection lights are designed so as to be sequentially arranged in the longitudinal direction, and the positional deviation amount and the mutual position between the element projection lights formed on the image carrier in the moving direction of the image carrier. Based on the relationship, each element array projection on the image carrier Light is characterized in that an exposure controller is provided for controlling lighting of each element row so as to be aligned in a straight line.

According to this, since the required number of grating light valve elements are formed by being divided into a plurality of element rows, the total length of each element row is such that the required number of elements in the related art is included in one element row. It can be shorter than the side-by-side configuration. Therefore, the optical modulator can be miniaturized and can be manufactured with high yield using the current semiconductor technology.

In the above structure, the optical section is designed so that the element array projection light projected on the image carrier by each element array is sequentially arranged in the longitudinal direction. In this case, In order to make it look like it is also composed of one element array, it is necessary to arrange the projection light of each element array in a straight line. However, it is difficult to arrange the projected light of each element array in the moving direction of the image carrier without displacement, and in order to correct such displacement, fine adjustment in units of micron is required, and mechanical adjustment is required. The method is difficult, and the adjustment requires a lot of time.

Therefore, in the above-mentioned structure, the exposure control means controls the image based on the positional shift amount in the moving direction of the image carrier and the mutual positional relationship between the projection lights of the element rows formed on the image carrier. The lighting of each element row is controlled so that the projection light of each element row is aligned on the carrier. Therefore, the positional deviation in the moving direction of the image carrier between the projection lights of the respective element arrays can be corrected without requiring fine adjustment in units of micron or requiring a great adjustment time.

As a method for obtaining the positional deviation amount in the moving direction of the image carrier and the mutual positional relationship between the projection lights of the respective element rows formed on the image carrier, for example, the following claims 2 and 6 can be used. As a more specific method of the method of claim 2, there are, for example, claims 3, 4, and 5, and as a more specific method of claim 6, there is, for example, claim 7.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a second aspect of the present invention is the exposure condition setting method for an optical modulator in the image forming apparatus according to the first aspect, in which the exposure condition is set. By arranging the projection light detection means so as to have the same positional relationship as the image carrier, and detecting the element row projection light by this projection light detection means, the image carrier movement direction between the element row projection lights It is characterized in that the lighting timing of each element row is determined by detecting the positional deviation amount and mutual positional relationship.

According to this, like the method of claim 6 described later, the electrostatic latent image formed by the element array projection light is not visualized, and the image carrier moving direction between the element array projection lights is changed. It is possible to detect the positional shift amount and the mutual positional relationship.

According to a third aspect of the present invention, in the exposure condition setting method for the optical modulator in the image forming apparatus according to the second aspect, the light receiving width in the longitudinal direction of the element array projection light in the projection light detecting means is obtained. Is larger than the distance between the element projection lights in the same direction.

According to this, since the light receiving width in the longitudinal direction of the element array projection light is larger than the interval between the element projection light in the same direction,
When detecting the element array projection light, it is possible to avoid the problem that the element array projection light cannot be detected because the light receiving area enters the unexposed area between the element projection light.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a fourth aspect of the present invention is the method according to the second aspect, in which two element rows are turned on at the same time and one of the element rows is the first element row. When the projection light and the element row projection light of the other second element row are detected substantially at the same time, it is determined that there is no positional deviation between the element row projection lights, and if they are not detected at substantially the same time, it is determined that there is a positional deviation. If it is determined that there is a position shift, the first element row is turned on while rotating the projection light detection means at a constant speed, and the second element row projection light is detected after the first element row projection light is detected. Similarly, the first element row is turned on, the first element row projection light is detected, and then the first element row is turned off and the second element row is turned on at the same time. Second time until detecting the second element array projection light Measured, it is characterized by detecting these first hour and positional deviation amount by comparing the second time and the mutual positional relationship.

According to this, the positional deviation amount and the mutual positional relationship are detected only when it is determined that the positional deviation exists, so that the time required for setting the exposure condition can be shortened.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a fifth aspect of the present invention is the method according to the second aspect, in which two element columns are turned on at the same time and one of the first element columns is turned on. When the projection light and the element row projection light of the other second element row are detected substantially at the same time, it is determined that there is no positional deviation between the element row projection lights, and if they are not detected at substantially the same time, it is determined that there is a positional deviation. If it is determined that there is a positional deviation, the reference signal is generated when the projection light detection means reaches a specific position while rotating the projection light detection means at a constant speed, and the first signal is generated at the same time when the reference signal is generated. The first row from the generation of the reference signal to the detection of the projection light of the element row is measured by turning on the element row, and similarly, the second element row is turned on at the same time as the generation of the reference signal from the generation of the reference signal. Until detecting the projection light of the element array Second time to measure, is characterized by detecting a positional deviation amount and the mutual positional relationship by comparing the first duration thereof with the second required time.

According to this, only when it is determined that there is a positional deviation, the positional deviation amount and the mutual positional relationship are detected, and the generation position of the reference signal is set to an appropriate position. Since the time required for measuring 1 hour and the second time can be shortened, the time required for setting the exposure conditions can be further shortened.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a sixth aspect of the present invention is the exposure condition setting method for an optical modulator in the image forming apparatus according to the first aspect, in which the exposure condition is set. At this time, a visible image detecting means for detecting a visible image formed on the image carrier is provided, and the visible image detecting means visualizes the electrostatic latent image formed by each element array projection light. By detecting the element row visible image for one pixel, the amount of positional deviation in the moving direction of the image carrier between each element row projection light and the mutual positional relationship are detected, and the lighting timing of each element row is determined. It is characterized by doing.

According to this, since each element row needs to be turned on for one pixel, deterioration of the grating light valve element can be suppressed more than in the method of claim 2. Further, the visible image detecting means can be used for image quality correction after being used for setting the exposure condition.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a seventh aspect of the present invention is the method according to the sixth aspect, wherein two element rows are simultaneously turned on for one pixel and one of the first element rows is turned on. When the visible image of the element array by the projection light of the element array and the visible image of the second element array by the projection light of the other second element array are detected almost at the same time, there is no displacement between the projection lights of the element arrays. On the other hand, if it is determined that there is no positional deviation, it is determined that there is positional deviation, and if it is determined that there is positional deviation, when the image bearing member reaches a specific position while rotating the image bearing member at a constant speed. A reference signal is generated, the first element row is turned on for one pixel at the same time when the reference signal is generated, and the first time from the generation of the reference signal to the detection of the element row visible image is measured. At the same time when the reference signal is generated, the second
The element array is turned on for one pixel, the second time from the generation of the reference signal to the detection of the visible image of the element array is measured, and the first time and the second time are compared, and the positional deviation amount and the mutual It is characterized by detecting the positional relationship.

According to this, only when it is determined that there is a positional shift, the positional shift amount and the mutual positional relationship are detected, and the generation position of the reference signal is set to an appropriate position. Since the time required for measuring 1 hour and the second time can be shortened, the time required for setting the exposure conditions can be further shortened.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] The following will describe one embodiment of the present invention with reference to FIGS. 1 to 11.

First, the overall structure of the optical printer which is the image forming apparatus of this embodiment will be described with reference to FIG.
The optical printer is provided with a paper feed tray 2 for inserting a plurality of sheet-shaped recording papers (transferred materials) on the side surface of the main body, and a lower end portion of the paper feed tray 2 is provided inside the optical printer as an image is formed. A paper feed roller 3 for sequentially feeding the recording paper is provided. Further, on the downstream side of the paper feed roller 3, a paper conveyance path 4 in which a PS sensor for detecting the front end of the recording paper is arranged is provided in a substantially horizontal direction, and a photoconductor that forms an electrostatic latent image is formed. A drum cartridge 5 having a drum (image carrier) 5a and a transfer roller 6 are arranged.

On the further downstream side of the transfer roller 6,
A U-turn guide provided with a fixing unit 7 having a fixing roller 7a for fixing the toner image formed on the recording paper and discharging the image-formed recording paper to a paper discharge tray 9 provided on the front cover of the main body. Eight. Above the drum cartridge 5, a developing device 11 for supplying toner to the surface of the photosensitive drum 5a is provided.
An optical unit (optical unit) 10 for irradiating the photoconductor drum 5 a with light is provided above the unit 1. Also,
Below the developing device 11, an optical sensor 16 for reading the toner image formed on the photosensitive drum 5a is provided.

Although the structure of the optical unit 10 will be described later, it includes a monochromatic light source unit, a collimator lens, a GLV optical modulator, a projection lens, and the like, and a control unit 13.

In the optical printer having the above structure, when a signal of a print command from an external device such as a personal computer is input to a control unit (not shown) of the main body of the optical printer, the operation of the optical printer is started based on the signal. Unit 10
The emitted light 12 corresponding to the image data is applied to the surface of the photosensitive drum 5a that has been charged in advance. Outgoing light 12
Is irradiated, the surface of the photoconductor drum 5a is exposed and an electrostatic latent image is formed on the surface of the photoconductor drum 5a.
This electrostatic latent image is developed by the toner supplied from the developing device 11 adhering to the photoconductor drum 5a to be a toner image (visible image), and this toner image is rotated as the photoconductor drum 5a rotates. , Is sent toward the contact portion between the photosensitive drum 5a and the transfer roller 6. In the middle of the process, the optical sensor 16 reads the reflection density of the toner image and sends it to a process controller (not shown) to control the image forming conditions of the image forming apparatus.

On the other hand, at this time, recording paper is supplied from the paper feed tray 2 by the paper feed roller 3, and the recording paper comes into contact with the photosensitive drum 5a and the transfer roller 6 along the paper conveyance path 4. It is conveyed to a transfer area which is a part. Then, when the recording paper passes through this area, the toner image formed on the surface of the photosensitive drum 5a is transferred to the recording paper due to the potential difference between the electric charge and the electric charge on the surface of the recording paper.

After that, the recording paper is sent to a fixing unit 7 having a fixing roller 7a, and is heated and pressed in the fixing unit 7, and the toner on the recording paper is fused to the recording paper by the heat and pressure of the fixing roller 7a. Be worn. Then, the recording paper sent out from the fixing unit 7 is guided above the main body along the U-turn guide 8 and is discharged onto a paper discharge tray 9 on a front cover that covers the main body.

Next, the optical unit 10 will be described in detail with reference to FIGS. 1 and 3 to 11. FIG. 1 (a)
Is a principle configuration diagram of the optical unit 10 (see FIG.
It is the same simplified drawing as (b). Here, a case where the GLV element array is divided into two is illustrated. The optical unit 10 is
As shown in FIG. 1A, it has two writing parts, one of which is a monochromatic light source unit (light source) 30a that emits monochromatic light and a light emitted from the monochromatic light source unit 30a is parallel light. A collimator lens 31a, a GLV optical modulator 32a that modulates the light emitted from the collimator lens 31a and irradiates the projection lens 33a through the slit 34a, and projects the emitted light onto the photoconductor drum 5a. Projection lens 33
a. Similarly, the other writing unit includes a monochromatic light source unit 30b, a collimator lens 31b, a slit 34b, a GLV optical modulator 32b, and a projection lens 33b. In FIG. 1A, the monochromatic light source units 30a and 30b and the collimating lenses 31a and 31b are shown shifted to the left or right for easy understanding.

The GLV optical modulator 32a has the same structure as that shown in FIG.
As shown in (b), a plurality of GLV elements 20 are arranged in a staggered manner in two stages to form a GLV element array 38a. Similarly, the GLV optical modulator 32b is also formed with a staggered array of GLV element arrays 38b. The GLV element arrays 38a and 38b are arranged such that the element array longitudinal direction corresponds to the width direction of the photosensitive drum 5a, and the diffraction angle θ of the GLV element 20 during lighting (ON control).
_The incident angle θ _i is selected and designed so that _d = 0 °.

Here, each of the above GLV element arrays 38a-3
The configuration and operating principle of the GLV element 20 constituting 8b are
This will be described with reference to FIGS. 4 to 6. Figure 4 shows one GLV
FIG. 7 is a perspective view of the element 20, and FIGS. 5 and 6 are operation principle diagrams thereof. As shown in FIG. 4, the GLV device 20 includes a substrate 2
1 has a structure in which a microbridge 22 integrally molded with a frame 24 is arranged between a frame 24 and a base 21 via a spacer 23. A space having the same thickness as the spacer 23 is formed between the two and 22, and the two are not in contact with each other. The thickness of the void determined by the spacer 23 and the thickness of the microbridge 22 are both the wavelength of the light source used, that is,
Here, if the emission wavelength is determined in advance by the wavelength of the emitted light of the monochromatic light source units 30a and 30b and the emission wavelength is λ nm,
Each is formed with λ / 4 nm. GL like this
The V element 20 can be manufactured by a fine semiconductor manufacturing technique.

The operation of the GLV element 20 is controlled by turning on and off the voltage applied between the microbridge 22 and the substrate 21, and the x-section of the GLV element 20 at the time of off control (light off) is shown in FIG. 5A. And the y cross section is shown in FIG. Further, FIG. 6A shows the GLV at the time of ON control (lighting).
The x section of the element 20 is shown, and the y section thereof is shown in FIG.

As shown in FIGS. 5 (a) and 5 (b), when the GLV element 20 is turned off, the microbridge 22 maintains a positional relationship of being separated from the substrate 21 by λ / 4 nm, and light is incident in this state. Then, the microbridge 22 and the base 21
The total optical path difference of each reflected light reflected by is equal to the wavelength of the incident light and reflects the light as a diffraction grating plane mirror.

On the other hand, as shown in FIGS. 6 (a) and 6 (b), GL
When the V element 20 is turned on, the microbridge 22 is pulled down by electrostatic force, and when light is incident in this state, the total optical path difference of each reflected light reflected by the microbridge 22 and the substrate 21 is a half wavelength (λ / 2), and the reflected lights interfere with each other to cancel each other and cause diffraction.

Further, as shown in FIG. 3, the optical unit 10 has a control unit 13 including a storage device, a controller unit, etc., which also has a function as an exposure control unit of the present invention.
Is provided, and the control unit 13 controls the lighting of the monochromatic light source units 30a and 30b and the GLV elements 20 that form the GLV element arrays 38a and 38b.

During operation of the optical printer, the monochromatic light source units 30a and 30b emit light under the control of the controller 13.
The light emitted from the monochromatic light source units 30a and 30b is collimated by the collimating lenses 31a and 31b, and is emitted obliquely from above toward the front of the GLV element arrays 38a and 38b arranged in a zigzag pattern of the GLV optical modulators 32a and 32b. To be done.

The GLV optical modulators 32a and 32b turn on and off the respective GLV elements 20 of the GLV element rows 38a and 38b in accordance with the image signal processed by the control unit 13 according to the above-mentioned operation principle, and turn on and off. Only the light reflected by the GLV element 20 passes through the slits 34a and 34b and is applied to the projection lenses 33a and 33b.

The light emitted to the projection lenses 33a and 33b is projected as individual pixels on the surface 35 of the photosensitive drum 5a. In the figure, what is shown by 36a and 36b is the element row projection light from each GLV element row 38a and 38b, and the individual box-like ones that constitute each element row projection light 36a and 36b are single. The element projection light from the GLV element 20 is a pixel (hereinafter, the element projection light is referred to as a single projection light).

By the way, the respective element array projection lights 36a and 36b from such two GLV element arrays 38a and 38b.
To be like the projection light projected by one GLV element array on the surface 35 of the photosensitive drum 5a,
Immediately next to the pixel at the end portion projected by the GLV element array 38a, it is necessary to continuously arrange the pixel at the end portion projected from the other GLV element array 38b. However, such fine adjustment requires adjustment in units of microns, which is difficult with a mechanical adjustment method, and the adjustment requires a large amount of time.

Therefore, the optical unit 10 of this optical printer is used.
Is assembled such that when all the GLV elements 20 of the GLV element rows 38a and 38b are turned on, the longitudinal ends of the element row projection lights 36a and 36b overlap near the center of the surface 35 of the photosensitive drum 5a. And some of the pixels overlap in the longitudinal direction. Then, in the control unit 13, at the time of image formation, one of the GLV element arrays 38 in the overlapping portion is formed.
The GLV device 20 of a / 38b is used. That is, the storage device of the control unit 13 stores the exposure control data including the use / non-use data of the GLV elements 20 of the GLV element arrays 38a and 38b during image formation, and the control unit 13 stores the exposure control data. GLV stored in
The image signal is processed by the controller section based on the use / non-use data of the element 20. As a result, the necessary GLV element 20 can be controlled as if it is composed of a single GLV element row, without requiring adjustment in units of micron or requiring a great amount of adjustment time.

However, in that case, each GLV optical modulator 3
It is necessary to attach optical systems 2a and 32b and collimating lenses 31a and 31 and projection lenses 33a and 33b so that the projection lights 36a and 36b are arranged in a straight line. However, although it is attached at a position determined by design, due to variations in assembly, as shown in FIG.
On the surface 35 of the photosensitive drum 5a,
May be displaced with respect to the moving direction (vertical direction in the figure). If such an attempt is made to adjust the positional deviation, adjustment in micron units and a great amount of adjustment time are required.

Therefore, the optical unit 10 of this optical printer is used.
Then, the positional displacement amount of each of the element array projection lights 36a and 36b and the mutual positional relationship are obtained, and data including the positional displacement amount and the mutual positional relationship is also stored in the storage device as exposure control data. Based on the displacement amount and the mutual positional relationship data, the GLV element arrays 38a and 38b are arranged so that the element array projection lights 36a and 36b are arranged on a straight line.
A target image is formed by shifting the lighting timing of.

Below, the projection light 36a, 36a for each element array
7 to 11 show a method of determining whether or not b is displaced in the moving direction of the photosensitive drum 5a, and if it is displaced, determining the amount of displacement and the mutual positional relationship.
This will be described with reference to FIG. Normally, according to this method, the presence or absence of positional deviation is determined, and if there is positional deviation, the amount of positional deviation and the mutual positional relationship are obtained, and stored in the storage device of the control unit 13. This is done before the installation, but it is possible to use the adjustment jig even after the installation.

FIGS. 8 (a) to 8 (c) are enlarged views of the overlapping portions of the above-mentioned element array projection lights 36a and 36b. FIG.
In each of (c) to (c), the element array projection lights 36a and 36b are intentionally overlapped in the longitudinal direction. On the other hand, when the element array projection lights 36a and 36b are almost overlapped with the direction orthogonal to the longitudinal direction (corresponding to the moving direction of the photoconductor drum) in FIG. If they overlap,
The same figure (c) is a case where it is largely separated.

For the adjustment, as shown in FIG. 7, an optical sensor (projection light detecting means) attached to the drum jig 15 is used.
This optical sensor 14 is used for the photosensitive drum 5 of FIG.
The light-receiving slit 37 is provided so as to have the same positional relationship as the surface 35 of a. The drum jig 15 is adapted to rotate at a constant speed in the arrow direction (see FIG. 8). As shown in FIGS. 8A to 8C, the element array projection lights 36a and 36b in the light receiving slit 37 are formed.
The width w1 in the longitudinal direction of each element array projection light 36a, 36b
Is sufficiently larger than the width w2 in the same direction of the single-projection light that constitutes the above-mentioned item, and has a length that spans the width of the plurality of single-projection lights.

First, the above-mentioned element array projection lights 36a, 36
It is determined whether or not b is displaced. In the determination, first, the GLV elements 2 of the GLV element rows 38a and 38b
All 0s are continuously turned on, and the projection light at that time is detected by the optical sensor 14. Then, based on the obtained sensor output of the optical sensor 14 and the predetermined reference detection duration time t and the prescribed time tx, the element array projection lights 36a.
It is determined whether 6b is displaced.

In the case of FIG. 8A, each element array projection light 36a
Since 36b is arranged on a straight line without being displaced in the direction orthogonal to the longitudinal direction, the change with time of the sensor output of the optical sensor 14 is as shown in FIG. 9 (a).
One small mountain with a short detection duration appears. The detection continuation time t1 which is the time when this mountain appears is calculated, and t1 is compared with the above-mentioned reference detection continuation time t. In this case, t1
Is within the range of t, that is, t1 is smaller than t, so that it is determined that there is no positional deviation between the element array projection lights 36a and 36b.
Further, at this time, the measurement of t1 may be repeated a plurality of times and the average value thereof may be used.

On the other hand, in the case of FIG. 8B, since the element array projection lights 36a and 36b are slightly deviated in the direction orthogonal to the longitudinal direction thereof, the change of the sensor output of the optical sensor 14 with respect to time is shown in FIG. As shown in 9 (b), a large mountain with a long detection duration appears. In this case, since the detection continuation time t2 is longer than the reference detection continuation time t, each element array projection light 36
It is determined that a and 36b are displaced.

Further, in the case of FIG. 8C, since the respective element array projection lights 36a and 36b are largely deviated in the direction orthogonal to the longitudinal direction thereof, the change of the sensor output of the optical sensor 14 with respect to time is as shown in FIG. 9 (c), each element array projection light 3
Small mountain corresponding to 6a and 36b (detection duration t3)
You can do two things. When a plurality of peaks are detected, one peak of the sensor output is detected, and when another peak is detected within the predetermined time tx determined in advance, each element row projection light 36a. It suffices to determine that the position 36b is displaced, and in FIG. 9C, the second mountain is detected within the time tx, so it is determined that the position 36b is displaced.

Projection lights 36a and 36b for each element array as described above.
If it is determined that there is no positional deviation in the determination as to whether or not the positional deviation has occurred, the subsequent checks are unnecessary and the adjustment time can be shortened.

Next, when it is determined that there is a positional deviation, the positional deviation amount and the mutual positional relationship are obtained. There are methods 1 and 2 described below as methods for obtaining the positional deviation amount and the mutual positional relationship. In either method, the element array projection lights 36a and 36b are slightly displaced in the direction orthogonal to the longitudinal direction. The case of FIG. 8B will be described as an example.

-Method 1-First, one of the GLV element arrays 38a and 38b, for example, the GLV elements 20 of the GLV element array 38b are all continuously illuminated. The change with time of the sensor output of the optical sensor 14 at that time is as shown in the upper part of FIG. At this time,
Since the optical sensor 14 is rotating at a constant speed in the direction of the arrow shown in FIG. 8A, when the optical sensor 14 goes around by the rotation of the drum jig 15, the peak of the sensor output is detected again. Here, the time t4 from the detection of the peak of the first sensor output to the detection of the second peak is measured.

When t4 is measured, the peak of the first sensor output is continuously detected with all the GLV elements 20 of the GLV element row 38b being lit, and then the GLV element row 38 is detected.
All the GLV elements 20 of b are turned off, all the GLV elements 20 of the other GLV element row 38a are continuously turned on, and the time t5 until the peak of the second sensor output is detected is as shown in the lower part of FIG. Measure.

From the difference between the times t4 and t5 thus obtained and the time difference, and the rotational speed of the optical sensor 14, the amount of positional deviation of the element array projection lights 36a and 36b and the mutual positional relationship are determined. That is, here, since t5 is larger than t4, it is understood that the GLV element array 38a that is turned on later is displaced toward the front side in the moving direction of the optical sensor 14 than the GLV element array 38b that is turned on earlier. . This means that on the surface of the photoconductor drum 5a in FIG. 2, it shifts to the front side in the moving direction of the photoconductor drum 5a.

The rotational speed (peripheral speed) of the optical sensor 14 is V, and the distance of the positional deviation is R (see FIG. 8).
(See (b)), R = V × (t5−t4) (2) At this time, the above t4 and t5 measurements may be repeated a plurality of times and the average value thereof may be used.

-Method 2-The drum-shaped jig 15 to which the optical sensor 14 is attached is
The reference signal 40 is generated when rotating at a constant speed in the direction of the arrow and when the rotational position reaches a predetermined rotational position.

When the reference signal 40 is generated, for example, all the GLV elements 20 in the GLV element array 38b are continuously turned on. The change with time of the sensor output of the optical sensor 14 at that time is as shown in the upper part of FIG. The time t6 from the generation of the reference signal 40 to the detection of the projection light by the optical sensor 14 from such sensor output.
Is measured. Thereafter, t7 is measured in the same manner for the other GLV element array, for example, all GLV elements 20 in the GLV element array 38a, as shown in the lower part of FIG.

From the magnitudes of the times t6 and t7 thus obtained and the time difference and the rotation speed of the optical sensor 14, the amount of positional deviation of the element array projection lights 36a and 36b and the mutual positional relationship are performed in the same manner as in the above method 1. To decide. At this time,
You may repeat the measurement of said t6 and t7 several times, and may use the average value.

In this method 2, by setting the reference signal 40 at an appropriate position, the time of t6 and t7 can be shortened as compared with t4 and t5 of the above method 1, so that the accuracy becomes higher. The measurement time is also shortened. In addition, the GLV element 2
Since the lighting time of 0 can be shortened, deterioration of the GLV element 20 can be reduced. The method 2 is only an example using the reference signal and is not limited to this.

The amount of positional deviation in the moving direction of the photoconductor drum 5a of the element array projection lights 36a and 36b and the mutual positional relationship thus determined, and the GLV element arrays 38a and 38b in the overlapping portion are determined. The control unit 13 processes the image signal in the controller unit based on the use / non-use data of the GLV device 20, and the GLV device array 38 is processed based on the mutual positional relationship.
The target image is formed by shifting the lighting timings of a and 38b.

Further, the amount of positional deviation in the moving direction of the photoconductor drum 5a and the mutual positional relationship between the respective element array projection lights 36a and 36b determined in this way are determined by the optical unit 10.
When the optical unit 10 is stored in the storage device of the control unit 13 and is installed in the optical printer main body, and then read by the control device on the optical printer main body side, the assembly process of the optical unit or the optical unit is replaced midway. Sometimes, it is not necessary to do extra work, so the work process and time can be shortened.

As described above, in the optical unit 10 of the present optical printer, the GLV element 20 is used as the optical modulator, and the required number of GLV elements 20 are arranged in the GLV element array 38.
a. 38b and GLV element array 38a. 3
8b is designed so that the element-row projection lights 36a and 36b projected onto the photoconductor drum 5a are sequentially arranged in the longitudinal direction thereof, and the control unit 13 controls each element-row projection light 36a. The positional deviation amount of 36b and the mutual positional relationship are obtained, and the data including the positional deviation amount and the mutual positional relationship is also stored in the storage device as exposure control data, and the positional deviation amount and the mutual positional relationship are formed during image formation. On the basis of the above data, the lighting timings of the GLV element arrays 38a and 38b are shifted so that the element array projection lights 36a and 36b are arranged on a straight line.

As a result, the total length of each element array can be shortened as compared with the conventional configuration in which the required number of GLV elements 20 are arranged in one element array, so that the optical modulator can be downsized and the yield can be improved by the current semiconductor technology. Can be manufactured well.

Then, the control unit 13 determines the amount of positional deviation in the moving direction of the photoconductor drum 5a and the mutual positional relationship between the element array projection lights 36a and 36b formed on the photoconductor drum 5a. Since the lighting timings of the GLV element arrays 38a and 38b are shifted so that the element array projection lights 36a and 36b are aligned on the photosensitive drum 5a, the image carrier of the element array projection lights 36a and 36b can be obtained. It is possible to correct the positional deviation in the moving direction without requiring fine adjustment in units of microns and a great amount of adjustment time.

Further, since the irradiation light from the light source is modulated by the GLV element arrays 38a and 38b, the recent high speed and high image quality using the halftone which cannot be dealt with by the conventional optical modulator composed of the polygon scanner. It becomes possible to meet the print request.

Moreover, in the case of this optical printer, since the GLV elements 20 forming the GLV element rows 38a and 38b are arranged in a staggered pattern, further miniaturization is possible and the GLV elements 20 are The generation of an unexposed region due to the diffraction ineffective region generated in the connecting portion with the GLV element 20 is caused by the GLV element 2 in the other GLV element row located in the connecting portion.
There is also an effect that it can be compensated by exposure with 0.

The number and positions of the optical sensors used in the present embodiment, the shape of the light-receiving slit, and the specific measuring method are not limited to those in the present embodiment, and the positions of the projected light of a plurality of GLV element arrays are not limited to the above. Any value may be used as long as it is possible to determine the shift amount and the mutual positional relationship.

[Second Embodiment] The following will describe another embodiment of the present invention in reference to FIG. 2 and FIGS. 12 to 14. For convenience of explanation, members having the same functions as those of the members described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The overall configuration of the optical printer which is the image forming apparatus of the present embodiment is the same as that of the optical printer of the first embodiment shown in FIG. 2, except that each element array projection light 36a. The method for determining whether or not 36b is displaced in the moving direction of the photosensitive drum 5a, and the method for determining the amount of positional displacement and the mutual positional relationship when the position is displaced is different.

This other method will be described with reference to FIGS. Normally, this method is used for the optical unit 10
After installing in the printer.

12A to 12C show the GLV element array 3
The photosensitive drum 5 is exposed by the respective element row projection lights 36a and 36b when the pixels are simultaneously turned on for one pixel time without considering the staggered arrangement in 8a and 38b.
FIG. 4 is an enlarged view of an overlapping portion of the element row toner images 41a and 41b when the electrostatic latent image formed on the surface of a (see FIG. 2) is developed. In each of FIGS. 7A to 7C, the element row toner image 41 is formed.
a and 41b are purposely overlapped in the longitudinal direction.
On the other hand, in the element row toner images 41a and 41b, when the figure (a) is substantially overlapped with the direction (corresponding to the moving direction of the photoconductor drum) orthogonal to the longitudinal direction, the figure (b) is almost the same. The case of overlapping is the case of large separation in FIG.

For the adjustment, an optical sensor (visible image detecting means) 16 arranged below the developing device 11 is used (see FIG. 2). The optical sensor 16 is fixedly provided so as to measure reflection on the surface of the photosensitive drum 5a after the electrostatic latent image on the surface of the photosensitive drum 5a is developed, and limits the measurement surface on the surface of the photosensitive drum 5a. A light receiving slit 42 is provided. The photosensitive drum 5a is adapted to rotate at a constant speed in the arrow direction (see FIG. 12). It should be noted that, as shown in FIGS.
2, the width w3 in the longitudinal direction of the element row toner images 41a and 41b is more than the single toner image (single projection light toner image) forming each element row toner image 41a and 41b, that is, the width w4 in the same direction of the pixels. Is sufficiently large and has a length that spans the width of multiple pixels.

First, the element array toner images 41a, 41
It is determined whether or not b is displaced. In the determination, first, the GLV elements 2 of the GLV element rows 38a and 38b
0 is turned on for the time corresponding to one pixel. The electrostatic latent image formed by lighting at this time is developed by the developing device 11 and becomes the element row toner images 41a and 41b. The optical sensor 16 detects the element array toner images 41a and 41b at that time. Then, based on the obtained sensor output of the optical sensor 16, the predetermined reference detection continuation time k, and the predetermined specified time kx, the element row toner images 41a.
It is determined whether 1b is displaced. FIG.
In the case of (a), since the respective element row toner images 41a and 41b are arranged on a straight line without shifting in the direction orthogonal to the longitudinal direction thereof, the change with time in the sensor output of the optical sensor 16 is shown in FIG. As shown in (a), one small valley appears. The detection continuation time k1 that is the time when this valley appears is calculated, and k1 is compared with the reference detection continuation time k. In this case, k1 is within the range of k, that is, k1 is greater than k1.
Is small, it is determined that there is no positional deviation between the element row toner images 41a and 41b (that is, there is no positional deviation between the element row projection lights 36a and 36b (see FIG. 1) of the GLV element rows 38a and 38b). Further, at this time, the measurement of k1 may be repeated a plurality of times and the average value thereof may be used.

On the other hand, in the case of FIG. 12B, since the element toner images 41a and 41b are slightly displaced in the direction orthogonal to the longitudinal direction, the change in the sensor output of the optical sensor 16 with respect to time is shown in FIG. A large valley appears as in (b). In this case, since the detection continuation time k2 is longer than the reference detection continuation time k, it is determined that the element row toner images 41a and 41b are displaced.

Further, in the case of FIG. 12C, since the toner images 41a and 41b of each element array are largely displaced in the direction orthogonal to the longitudinal direction thereof, the change of the sensor output of the optical sensor 16 with respect to time is as shown in FIG. As shown in 13 (c), two small valleys (detection continuation time k3) corresponding to the toner images 41a and 41b of each element array are formed. If multiple valleys are detected,
After detecting one trough of the sensor output, when another trough is detected within the predetermined time kx determined in advance, it is determined that the toner images 41a and 41b of the respective element arrays are misaligned. The second valley is detected within kx time in FIG. 13C, so it is determined that the position is displaced.

Such element array toner images 41a and 41b
If it is determined that there is no position shift in the determination as to whether or not there is a position shift, the subsequent checks are unnecessary and the adjustment time can be shortened.

Next, when it is determined that there is a positional deviation, the positional deviation amount and the mutual positional relationship are obtained. A method of obtaining the positional deviation amount and the mutual positional relationship will be described by exemplifying the case of FIG. 12B in which the element row toner images 41a and 41b are slightly deviated in the direction orthogonal to the longitudinal direction thereof.

The photosensitive drum 5a is rotated in the direction of the arrow at a constant speed, and the reference signal 43 is generated when it reaches a predetermined rotational position. When the reference signal 43 is generated, for example, the GLV element array 3
All of the 8b GLV elements 20 are turned on for a time corresponding to one pixel. The change with time of the sensor output of the optical sensor 16 at that time is as shown in the upper part of FIG. From such sensor output, time k from generation of the reference signal 43 to detection of the element row toner image 41b by the optical sensor 16
Measure 4.

Thereafter, k5 is similarly measured for the other GLV element array, for example, all GLV elements 20 in the GLV element array 38a, as shown in the lower part of FIG.

From the magnitudes of the times k4 and k5 thus obtained, the time difference, and the rotation speed of the optical sensor 16, the toner images 41a and 41b, that is, the toner images 41a and 41b of the respective element rows, that is, the method 1 shown in the first embodiment, are obtained. Element array projection light 36a / 36b
The amount of positional deviation and mutual positional relationship are determined. Also at this time, the above k4 and k5 may be repeated a plurality of times and the average value thereof may be used.

In this method, by setting the reference signal 43 at an appropriate position, the time of k4 and k5 can be shortened, so that the measurement time is also shortened. Further, this method is only an example using the reference signal, and the method is not limited to this.

In the above method, the case where the zigzag arrangement of the GLV elements 20 is not taken into consideration has been described. However, when the zigzag arrangement of the GLV elements 20 has already been dealt with at the time of writing, one horizontal line is provided for each of the GLV element rows 38a and 38b. If the lines are written, the positional shift amount of each of the element array projection lights 36a and 36b and the mutual positional relationship can be determined by the same process.

In the case of the present optical printer, after the above adjustment is completed, the optical sensor 16 is used to measure the reflectance of the toner patch image formed on the photosensitive drum 5a. As an example, the density (reflectance) of the toner patch image is measured under a predetermined image forming condition, and the charging voltage of the photosensitive drum 5a is increased or decreased so that the measurement result has a predetermined density (reflectance). Or control other image forming conditions. By doing so, it is possible to form a stable image for a long period of time regardless of the environment. It goes without saying that the above is an example of the control of the image forming conditions using the optical sensor 16 and is not limited to the above method.

The number and positions of the optical sensors used in the present embodiment, the shape of the light-receiving slit, and the specific measuring method are not limited to those in the present embodiment, and the positions of the projected light of a plurality of GLV element arrays are not limited to the above. Any value may be used as long as it is possible to determine the shift amount and the mutual positional relationship.

[0101]

As described above, in the image forming apparatus according to the first aspect of the present invention, the optical modulator has a plurality of element rows in each of which a plurality of grating light valve elements are arranged, and Is designed such that the element array projection light, which is composed of a plurality of element projection light projected on the image carrier by each of these element arrays, is sequentially arranged in the longitudinal direction thereof, and the image carrier Based on the positional shift amount in the moving direction of the image carrier between the respective element array projection lights formed on each other and the mutual positional relationship, each element array projection light is aligned on the image carrier This is a configuration provided with an exposure control means for controlling the lighting of the row.

As a result, the total length of each element row can be shortened as compared with the conventional configuration in which a required number of grating light valve elements are arranged in one element row, so that the optical modulator can be downsized and the present semiconductor technology can be used. Can be manufactured with good yield.

Further, in the above-mentioned structure, the exposure control means determines, based on the positional shift amount in the moving direction of the image carrier and the mutual positional relationship between the respective element row projection lights formed on the image carrier.
Since the lighting of each element row is controlled so that the projection light of each element row is aligned on the image carrier, the positional deviation of the projection light of each element row in the moving direction of the image carrier is finely adjusted in units of micron or large. It can be corrected without requiring a long adjustment time.

Further, since the irradiation light from the light source is modulated by the element array composed of the grating light valve elements, the recent high speed and halftone which cannot be handled by the conventional optical modulator composed of the polygon scanner are used. It also has the effect of being able to meet the demand for high quality printing.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a second aspect of the present invention is the exposure condition setting method for an optical modulator in the image forming apparatus according to the first aspect, in which the exposure condition is set. By arranging the projection light detection means so as to have the same positional relationship as the image carrier, and detecting the element row projection light by this projection light detection means, the image carrier movement direction between the element row projection lights The position shift amount and the mutual positional relationship are detected, and the lighting timing of each element row is determined.

As a result, it is possible to detect the positional deviation amount in the moving direction of the image carrier between the element array projection lights and the mutual positional relationship without visualizing the electrostatic latent image formed by the element array projection light. Therefore, it can be performed before the optical unit is incorporated in the main body of the image forming apparatus.

Further, the exposure condition setting method of the optical modulator in the image forming apparatus according to claim 3 of the present invention is the method according to claim 2, wherein the light receiving width in the longitudinal direction of the element array projection light in the projection light detecting means. Is larger than the distance between the element projection lights in the same direction.

Thus, when detecting the element array projection light, it is possible to avoid the problem that the light receiving area enters the unexposed area between the element projection light and the element array projection light cannot be detected.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a fourth aspect of the present invention is the method according to the second aspect, in which two element rows are turned on at the same time and one of the first element rows is an element row. When the projection light and the element row projection light of the other second element row are detected substantially at the same time, it is determined that there is no positional deviation between the element row projection lights, and if they are not detected at substantially the same time, it is determined that there is a positional deviation. If it is determined that there is a position shift, the first element row is turned on while rotating the projection light detection means at a constant speed, and the second element row projection light is detected after the first element row projection light is detected. Similarly, the first element row is turned on, the first element row projection light is detected, and then the first element row is turned off and the second element row is turned on at the same time. Second time until detecting the second element array projection light Measured, and detects the positional deviation amount and the mutual positional relationship by comparing with these first hour and the second hour. Thereby, the exposure condition can be easily set in a short time.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a fifth aspect of the present invention is the method according to the second aspect, in which two element rows are turned on at the same time and one of the first element rows is an element row. When the projection light and the element row projection light of the other second element row are detected substantially at the same time, it is determined that there is no positional deviation between the element row projection lights, and if they are not detected at substantially the same time, it is determined that there is a positional deviation. If it is determined that there is a positional deviation, the reference signal is generated when the projection light detection means reaches a specific position while rotating the projection light detection means at a constant speed, and the first signal is generated at the same time when the reference signal is generated. The first row from the generation of the reference signal to the detection of the projection light of the element row is measured by turning on the element row, and similarly, the second element row is turned on at the same time as the generation of the reference signal from the generation of the reference signal. Until detecting the projection light of the element array The second time was measured for, and detects the positional deviation amount and the mutual positional relationship by comparing the first duration thereof with the second required time. Thereby, the exposure condition can be easily set in a shorter time.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a sixth aspect of the present invention is the exposure condition setting method for an optical modulator in the image forming apparatus according to the first aspect, in which the exposure condition is set. At this time, a visible image detecting means for detecting a visible image formed on the image carrier is provided, and the visible image detecting means visualizes the electrostatic latent image formed by each element array projection light. By detecting the element row visible image for one pixel, the amount of positional deviation in the moving direction of the image carrier between each element row projection light and the mutual positional relationship are detected, and the lighting timing of each element row is determined. To do.

As a result, each element row needs to be turned on for one pixel, so that the deterioration of the grating light valve element can be suppressed more than in the method of claim 2. Further, the visible image detecting means can be used for image quality correction after being used for setting the exposure condition.

An exposure condition setting method for an optical modulator in an image forming apparatus according to a seventh aspect of the present invention is the method according to the sixth aspect, wherein two element rows are simultaneously turned on by one pixel and one of the first element rows is turned on. When the visible image of the element array by the projection light of the element array and the visible image of the second element array by the projection light of the other second element array are detected almost at the same time, there is no displacement between the projection lights of the element arrays. On the other hand, if it is determined that there is no positional deviation, it is determined that there is a positional deviation, and if it is determined that there is a positional deviation, when the image bearing member reaches a specific position while rotating the image bearing member at a constant speed. A reference signal is generated, the first element row is turned on for one pixel at the same time when the reference signal is generated, and the first time from the generation of the reference signal to the detection of the element row visible image is measured. At the same time when the reference signal is generated, the second
The element array is turned on for one pixel, the second time from the generation of the reference signal to the detection of the visible image of the element array is measured, and the first time and the second time are compared, and the positional deviation amount and the mutual The positional relationship is detected. Thereby, the exposure condition can be easily set in a short time.

[Brief description of the drawings]

1A and 1B show an embodiment of the present invention, in which FIG. 1A is a simplified diagram showing a configuration of an optical unit in an optical printer, and FIG. 1B is a description showing a grating light valve element array of the optical unit. It is a figure.

FIG. 2 is a configuration diagram of the optical printer.

FIG. 3 is a block diagram showing a control system of an optical unit of the optical printer.

FIG. 4 is a perspective view of one grating light valve element.

FIG. 5 is an operation principle diagram when the grating light valve element is turned off (during off control).

FIG. 6 is a diagram illustrating an operation principle when the grating light valve element is turned on (at the time of ON control).

FIG. 7 is a perspective view of a drum jig to which an optical sensor is attached, which is used for setting an exposure condition in the optical modulator.

FIG. 8 is an explanatory diagram showing an overlapping portion of element array projection light.

FIG. 9 is an explanatory diagram showing a change over time in sensor output in the optical sensor.

FIG. 10 is an explanatory diagram showing a time change of a sensor output in the optical sensor.

FIG. 11 is an explanatory diagram showing a time change of a sensor output in the optical sensor.

FIG. 12 is an explanatory diagram showing an overlapping portion of an element row toner image for one pixel in which an electrostatic latent image formed by element row projection light is visualized.

FIG. 13 is an explanatory diagram showing a time change of a sensor output in the optical sensor.

FIG. 14 is an explanatory diagram showing a time change of a sensor output in the optical sensor.

15A is a perspective view of an optical system when a conventional technique is used for writing in a printer or the like, and FIG. 15B is a simplified diagram thereof.

[Explanation of symbols]

5a Photoreceptor drum (image bearing member) 10 Optical unit (optical part) 13 Control part (exposure control means) 20 GLV element (grating light valve element) 30a Monochromatic light source unit (light source) 30b Monochromatic light source unit (light source) 32a GLV Optical modulator (optical modulator) 32b GLV optical modulator (optical modulator) 36a Element row projection light 36b Element row projection light 38a GLV element row (element row) 38b GLV element row (element row) 41a Element row toner image ( Element array visible image) 41b Element array toner image (element array visible image)

Claims (7)

[Claims] 1. A static image formed on the image carrier by the projection light from the optical unit, the optical unit modulating an irradiation light from a light source with an optical modulator and projecting the modulated light onto the image carrier. In an image forming apparatus that visualizes a latent electric image and then transfers it to a transfer material and discharges it, the optical modulator has a plurality of element rows in which a plurality of grating light valve elements are arranged,
The optical unit is designed so that element array projection light, which is composed of a plurality of element projection light projected on the image carrier by each of these element arrays, is sequentially arranged in the longitudinal direction, and Based on the positional deviation amount in the image carrier moving direction between the element array projection lights formed on the carrier and the mutual positional relationship, the element array projection lights are aligned on the image carrier. An image forming apparatus comprising: an exposure control unit that controls lighting of each element array. 2. A method of setting exposure conditions for an optical modulator in an image forming apparatus according to claim 1, wherein the projection light detecting means is arranged so as to have the same positional relationship as that of the image carrier when setting the exposure conditions, By detecting each element row projection light by this projection light detection means, the positional deviation amount in the image carrier moving direction between each element row projection light and the mutual positional relationship are detected, and the lighting timing of each element row is determined. A method for setting an exposure condition of an optical modulator in an image forming apparatus, characterized by: 3. The optical modulation in the image forming apparatus according to claim 2, wherein a light receiving width in the longitudinal direction of the element array projection light in the projection light detection means is larger than a space between the element projection lights in the same direction. Exposure condition setting method. 4. When the two element rows are turned on at the same time and the element row projection light of one of the first element rows and the element row projection light of the other of the second element rows are detected at substantially the same time, each element row projection On the other hand, it is determined that there is no positional deviation between the light beams, but if they are not detected at substantially the same time, it is determined that there is a positional deviation. Is lit, the first time from the detection of the first element row projection light to the detection of the second element row projection light is measured, and similarly, the first element row is turned on and the first time element is turned on. First after detecting the column projection light
The second element row is turned on at the same time when the element row is turned off, the second time until the second element row projection light is detected is measured, and the first time and the second time are compared, and the positional deviation amount and An exposure condition setting method for an optical modulator in an image forming apparatus according to claim 2, wherein mutual positional relationships are detected. 5. When the two element rows are turned on at the same time and the element row projection light of one of the first element rows and the element row projection light of the other of the second element rows are detected at substantially the same time, each element row projection While it is determined that there is no positional deviation between the light beams, if it is determined that there is no positional deviation at substantially the same time, and if it is determined that there is a positional deviation, the projection light detecting means is rotated while rotating the projection light detecting means at a constant speed. Generates a reference signal when it reaches a specific position, turns on the first element row at the same time as the generation of the reference signal, and measures the first time from the generation of the reference signal to the detection of the element row projection light, Similarly, the second element array is turned on at the same time as the generation of the reference signal, and the second time from the generation of the reference signal to the detection of the element array projection light is measured, and the first required time and the second required time are calculated. By comparing the positional deviation amount and the mutual positional relationship. Exposure condition setting method for an optical modulator in the image forming apparatus according to claim 2, characterized in that the output. 6. A method for setting an exposure condition of an optical modulator in an image forming apparatus according to claim 1, wherein a visible image detecting means detects a visible image formed on an image carrier when setting the exposure condition. Is arranged, and the visible image detecting means detects a visible image of the element array for one pixel in which the electrostatic latent image formed by the projection light of the element array is visualized. An exposure condition setting method for an optical modulator in an image forming apparatus, comprising: detecting a positional deviation amount between light beams in a moving direction of an image carrier and a mutual positional relationship to determine a lighting timing of each element array. 7. Two element rows are simultaneously turned on for one pixel, and a visible image of the element row by the element row projection light of one first element row and a second element row projection light of the other second element row. When element array visible images are detected at almost the same time, it is determined that there is no misalignment between the projection lights of each element array, and if they are not detected to be approximately the same, it is determined that there is misalignment, and if it is determined that there is misalignment. While rotating the image carrier at a constant speed, a reference signal is generated when the image carrier reaches a specific position, and at the same time when the reference signal is generated, the first element row is turned on for one pixel, The first time from the generation to the detection of the element array visible image is measured, and similarly, at the same time when the reference signal is generated, the second element array is turned on by one pixel, and the element signal is visible from the generation of the reference signal. The second time until the image is detected is measured, and these first time and second time Exposure condition setting method for an optical modulator in the image forming apparatus according to claim 6, wherein the detecting the positional deviation amount and the mutual positional relationship by comparing.