JPH02131959A - Exposure device - Google Patents

Abstract

PURPOSE:To always expose at a correct aligning scanning position even if conveying or positional irregularity occurs by detecting the conveying distance of a recording material, and controlling the exposure timing of exposure element array of the material on the basis of a conveying distance signal. CONSTITUTION:An exposure head 12 as a light source, conveying means 14, and a controller 16 for controlling exposure are provided. When the transfer of density data is finished, a raster of previous time is written, and a muP 40 is moved to a correct exposure position on the basis of a conveying distance signal from the rotary encoder 38 of the conveying means 14, exposure timing is output, one row of LED array 18 are emitted to expose a recording material 24 to write a rester. Even if the means 14 has irregular conveying speed and conveyance, no scanning positional deviation occurs due to the conveying positional deviation.

Description

Detailed Description of the Invention Industrial Field of Application The present invention relates to an exposure device using a linear exposure element array, and more specifically, to an exposure device that uses a linear exposure element array. This article concerns exposure equipment that can be eliminated. <Prior art> The rusk scan method, which is a scanning method used in television picture tubes, etc., is used to scan text, pictures, photographs, videos, and other images onto recording materials such as paper and film. It is used in the exposure device of an image recording device to obtain a visible image. This Rusk scan method is also called the television scan method, and it scans the screen sequentially in a one-dimensional direction, for example, from left to right, and sub-scans it in a direction approximately perpendicular to the main scanning direction, for example, from top to bottom. This is a scanning method.

In addition, a linear exposure element array such as an LED array is used, and the linear exposure element array is arranged in the main scanning direction in a rask scan method, and the recording material is conveyed in a direction substantially perpendicular to the exposure element array. A scanning method using an exposure element array that exposes and scans the recording material two-dimensionally is also used in the exposure device of the above-mentioned image recording apparatus.

Conventionally, in an image recording apparatus, an exposure apparatus using the above-mentioned rusk scan method causes a light beam emitted from a light source such as a semiconductor laser (LD) to carry image information.
In an exposure apparatus that uses a scanning method using an exposure element array, the light is deflected one-dimensionally by a light deflector such as a polygon mirror or a galvanometer mirror, and the light is exposed one-dimensionally by main scanning. The light beams simultaneously emitted in one row at predetermined time intervals from an exposure element array such as The image is transported by a transport means, sub-scanned, and exposed two-dimensionally to finally obtain a two-dimensional visible image on paper, film, or the like.

Therefore, on the recording material, a rask (main scanning line) is generated by the deflection of the optical deflector in the rask scanning method, and a rask (main scanning line) by simultaneous irradiation of one row by the exposure element array in the exposure element array method. ) are defined in parallel at regular intervals in the sub-scanning direction, forming a striped pattern rask at prescribed intervals.

Problems to be Solved by the Invention> By the way, in an exposure device that uses a light deflector such as a polygon mirror or a galvanometer mirror for main scanning and transports a recording material in sub-scanning mode, the control device in the device is In a rask scan type exposure apparatus, in which it is difficult to change the writing stitching timing of one line (one line) in order to control the main scanning and sub-scanning speeds according to a reference clock, the optical deflector is If there is a surface tilt and the surface tilt correction is not perfect or if there is unevenness in the conveyance of the recording material, the imaging position of the light beam will shift and the rask spacing will be uneven, that is, pitch unevenness will occur. In addition, even if the exposure device is an exposure element array type,
In an apparatus in which the exposure timing of the exposure element array is controlled according to a reference clock possessed by a control device within the apparatus, if there is uneven conveyance of the recording material, the imaging position of the light beam shifts, There are irregularities in the rask intervals and uneven bits.

For example, as shown in Figure 4, the spacing between the rusks is different from 1 ml.
As the color becomes darker, areas where the rusks are close together will appear darker, and areas where the rusks are far apart will appear lighter. Therefore, when an exposed image with pitch unevenness (irregularity) in the rask interval is made into a visible image,
Density unevenness occurred in the image, significantly impairing the quality of the visible reproduced image.

By the way, if the above-mentioned irregularity (pinch irregularity) in the rask interval (interval between main scanning lines) exceeds a certain amount, it will be recognized as a four-degree irregularity on the reproduced image. Therefore, in the past, in order to eliminate these density unevenness, it was necessary to improve the processing accuracy, operation accuracy, and assembly accuracy of optical deflectors such as polygon mirrors and galvanometer mirrors in order to suppress the irregularities in rask spacing to below a certain amount. Measures to improve accuracy have been taken, such as increasing the accuracy of the optical system for surface tilt correction to increase the amount of correction, and improving the feeding accuracy of the recording material conveyance system, particularly the sub-scanning conveyance means.

Not only is there a limit to improving the accuracy of such optical deflectors and sub-scanning conveyance means, but improving accuracy requires the use of expensive equipment and parts, which significantly increases costs. Ta.

Furthermore, when aiming for a low-cost device, there are limits to the use of such a method.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to improve the recording performance when two-dimensionally exposing using main scanning by simultaneous irradiation of one row by an exposure element array and sub-scanning by conveying the recording material. By controlling the exposure irradiation timing by the exposure element array based on the amount of withdrawal by the conveyance means for conveying the material, the recording can be performed without using a conveyance means with high assembly precision made of expensive and high precision components. An object of the present invention is to provide an exposure apparatus that can suppress unevenness (pitch unevenness) in rask intervals (intervals between main scanning lines) caused by uneven feeding of material, and can eliminate density unevenness caused by uneven rask intervals. .

Furthermore, in the present invention, even if irregularities occur in the rask intervals, the exposure amount is adjusted according to the irregularities in the rask intervals, thereby adjusting the density for each rask, canceling out the density unevenness, and preventing it from being recognized. The purpose of the present invention is to provide an exposure apparatus that can also perform

Means for Solving the Problems> In order to achieve the above object, the present invention provides a linear exposure element array for exposing a recording material, and a linear exposure element array for exposing the recording material to light in the arrangement direction of the linear exposure element array. Conveyance in a direction approximately perpendicular to ? a conveyance amount detection means for detecting the conveyance amount of the conveyance means; and a control means for controlling the exposure timing of the exposure element array based on the conveyance amount signal detected by the conveyance amount detection means. (1) It provides an exposure apparatus with the following characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exposure apparatus according to the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a perspective explanatory diagram including a flow of a control system of an embodiment of an exposure apparatus of the present invention.

The exposure apparatus of the present invention may be a monochrome image exposure apparatus or a color image exposure apparatus, but in this embodiment, it is typically a light emitting diode printer that uses an LED array as an optical writing exposure element array. A monochrome image exposure apparatus will be explained.

As shown in the figure, the exposure apparatus 10 of the present invention is a light emitting diode (LED) printer that uses an LED array in an optical writing system, and basically includes an exposure head 12 that serves as a light source.
, a transport means 14, and a control section 16 that controls exposure.

The exposure head 12 is an exposure light source, and includes an LED array 18 which is an exposure element array, and a selfoc lens array, a focusing rod lens array, etc., which images a light beam 22 emitted from the LED array 18 onto a recording material 24. It has a light guide 20, and the LED array 18 is integrated with the light guide 20. The LED array 18 has a large number of LEDs corresponding to each pixel that are densely integrated in one column for one line. There is. Usually, an LED array is composed of multiple array chips, and one chip has 64 to 64 chips.
256 LEDs are integrated, for example, an exposure head for A4 size uses 37 array chips, and each chip has 128 LEDs integrated at a density of 16 elements/mm, so Then, exposure is performed at intervals of 1/16 mm.

The light guide 20 is a self-cleaning lens array, a focusing lens array, or an optical fiber array, which is often used in 1-magnification systems, and is used to control exposure from an exposure element array, for example, the LED array 18 in FIG. Any transparent optical material can be used as long as it can conduct the light beam 22 to a recording material such as a photoreceptor or photosensitive material and form an image, and a suitable material can be selected depending on the light source, exposure element array, etc. used. do it.

The exposure head 12 has a built-in drive source consisting of a drive circuit for the LED array 18, a memory, etc., and each LE for one line according to the image information transmitted from the control unit 16.
The light emission amount of D is stored in memory, and when a light emission timing signal is transmitted, the LED array arranged in one column is configured to emit light for one row.

In the present invention, the exposure element array refers to a large number, for example, one
A device consisting of elements arranged in a row corresponding to the pixels so that a light beam having an exposure amount according to the image information of the pixel can be irradiated to a position on the recording material corresponding to a row of pixels. Yes, even if the exposure elements that form the array are light-emitting exposure elements that emit light by themselves, such as LEDs, they do not emit light themselves, but have a separate light source, such as liquid crystals, and the light intensity of the light beam from the light source is controlled. It may also be a non-emissive exposure element to be controlled.

Therefore, the exposure head used in the present invention includes a light-emitting element array and a light guide when using a light-emitting type exposure element array, and a light source, an exposure element array, and a light guide when using a non-emitting type exposure element array. It is an integrated structure, and any type of head that can be used as an ordinary exposure head can also be used. Such an exposure head does not require space for light deflection, has no moving parts, is highly reliable and easy to maintain, has high resolution, and can adjust the exposure amount corresponding to the image density using the WL1T flow of the exposure element. This can be done by controlling the energization time, and has excellent adaptability to gradation expression of reproduced images.

In the example shown in FIG. 1, the LED array 18 made of LEDs as light emitting elements is used as the exposure element array, but the invention is not limited to this, and any type of light source can be used as long as it can emit the exposure light beam 22 for one line. It may be either a light-emitting type or a non-light-emitting type. Even if it uses a light-emitting element, semiconductor laser (LD), EL, F
OT or the like can be used, and can be appropriately selected depending on the ease of forming a high-density array, economic efficiency, light emission output, wavelength matching with the photosensitivity of the recording material 24, and the like. In addition, in the case of a non-emissive exposure element array, it has a separate light source, electrically controls the amount of transmitted light beam from the light source, and irradiates the recording material with a light beam according to image information. Any type of material may be used, and for example, a liquid crystal cell array arranged in series, an optical shutter array made of an electro-optical material such as PLZT, etc. can be used. Further, the light source in this case may be any light source as long as it has the necessary amount of light, and for example, a light source such as a fluorescent lamp, a sodium lamp, a xenon lamp, a mercury lamp, a halogen lamp, etc. can be used.

An example of an exposure head using a liquid crystal cell array as a non-emissive exposure element array is shown in FIG. 2a.

As shown in the figure, the exposure head 5o has a linear light source 54 such as a fluorescent lamp inside a box 52, and a cylindrical lens 58 that focuses the light beam emitted from the light source 54 onto a liquid crystal cell array 56. The lower part of the liquid crystal cell array 56 is opened, and a light guide 59 is attached directly below the liquid crystal cell array 56.

The liquid crystal cell array 56 is made by arranging a large number of liquid crystals made of rod-shaped organic molecules in a line.There are three types of liquid crystal materials depending on the way the molecules are arranged: nematic liquid crystal, cholesderic liquid crystal, and smectic liquid crystal, but nematic liquid crystal is the main type. Liquid crystal is used. The IF-11 line cutaway diagram of a part of the exposure head 5o using a known liquid crystal cell array 56 formed by combining a torsional effect type liquid crystal element using nematic liquid crystal and a light polarizing plate shown in FIG. 2a is shown in the mZb diagram. . As shown in the figure, the liquid crystal cell array 56 includes a nematic liquid crystal cell array 56 with a sealing layer 61 interposed between two transparent glass plates, that is, an upper glass substrate 6oa and a lower glass substrate 6ob.
2 is enclosed, and optical polarizing plates 64a and 64b are arranged on the outside of both glass substrates Boa and 60b. On the inside of the upper glass substrate 60a on the side where incident light enters, a large number of transparent electrodes 66.86 constituting each liquid crystal cell are deposited at a predetermined length and at predetermined intervals. The transmitted light amount corresponding to the pixel exposure amount is i! This serves as a signal electrode for controlling J. Further, a common transparent electrode 68 is deposited inside the lower electrode 8i60b on the emission side, and inside the transparent electrode 68, there is a light shield between a large number of transparent electrodes 66, 66 in order to optically isolate each liquid crystal cell. A light shielding layer 70 is provided, and on these transparent electrodes 66, 66, 68 and the light shielding layer 70, organic liquid crystal alignment layers 11i72a, 72b provided with alignment performance in mutually orthogonal directions are provided.

Furthermore, both the polarizing plates 64a and 64b are arranged such that their polarization directions are perpendicular to each other. Lower glass substrate 60
In the liquid crystal cell array 56 configured in this way in b, the liquid crystal 62 between the transparent electrodes 66, 66 of each liquid crystal cell and the common transparent electrode 68 has a structure corresponding to the image information of the pixel corresponding to each liquid crystal cell. When a voltage is applied so that the amount of transmitted light is achieved, the amount of exposure to the recording material is controlled. Furthermore, the liquid crystal cell array 5
The reason why 6 changes its state so that the amount of transmitted light changes depending on whether a voltage is applied or not is well known, so the explanation thereof will be omitted.

The conveyance means 14 for sub-scanning may be of any type as long as it conveys the recording material 24 in the main scanning direction, that is, in the sub-scanning direction substantially perpendicular to the rask (main scanning line) 26, and may be of any type, depending on the form of the recording material 24. You can use the most suitable one depending on your needs. For example, when the recording material is a photosensitive drum, or when a sheet-like photosensitive material is used wound around a drum, the photosensitive drum or the drum itself constitutes the conveying means 14. If the recording material is a sheet-like photosensitive material, it can be constructed using a belt conveyor or two pairs of rollers as shown in FIG.

The transport stage 14 shown in FIG. 1 consists of two pairs of rollers 30 and 3.
1, 32, and 33, and supports and conveys a sheet-shaped recording material 24. A synchronous belt 34 is attached to one side of each of the lower rollers 30 and 32 of the two roller pairs.
is suspended and driven synchronously by a drive source 36 attached to the other side of the roller 30, to convey the recording material 24 at a constant speed. Of course, if the diameters of the rollers 30 and 32 are equal, these rollers 30 and 32 will rotate at a constant speed. The drive source 36, as shown in FIG.
Although it is attached to the rollers 30 of two pairs of rollers constituting 4, it is not limited to this example, and it may be attached to any roller, or it may not be directly connected to these rollers, but may be attached to a belt, chain, gear, etc. The two pairs of rollers may be driven via transmission means such as the above. A rotary encoder 38 is attached to the synchronous belt 34 side of the roller 30 for detecting the rotational speed of the roller 30, that is, the conveyance speed of the recording material 24. rotary encoder 3
8 is preferably attached to the roller 30 or 32 on the WAvJ side, but is not limited to the example shown in FIG. It can also be attached to. In the present invention, the rotary encoder 38 constitutes a conveyance amount detection means for detecting the conveyance amount or conveyance speed of the recording material 24 of the thousand conveyance stages 14, that is, the rotation amount or rotation speed of the rollers 30 and 31. Here, the conveyance amount detection means is not limited to the rotary encoder 38 attached to either of the two pairs of rollers constituting the conveyance means 14, but is originally built in a drive source such as the Senichita. You may also use a rotary encoder, etc. In the present invention, the conveyance amount information of the recording material $424 from the rotary encoder 38 is used to determine the exposure timing of the exposure head 12, but even though the recording material 24 has reached the exposure position, the exposure head If one line of image data has not been transferred to the memory of the recording material 24, the exposure timing is the end of the transfer.
It is also used to detect the difference between the above exposure position and the correct exposure position, that is, the amount of scanning position deviation. The control unit 16 is the most characteristic part of the present invention, and as shown in FIG. 1, it determines the exposure timing of the LED array 18 based on the conveyance amount signal detected by the rotary encoder 38, and If the timing is delayed, a microprocessor (hereinafter referred to as μP) 40 that calculates the scanning position shift and writing density, and a RAM 44 that stores density information or position and density information of the rask defined on the immediately preceding main scanning line, Memorize the density of the rask on the main scanning line to be written next time and write <RAM45.
The original density information of the rask on the main scanning line to be written this time is stored in RAM 42, and the current writing density information from RAM 42 is modulated, or if there is a scanning position shift, the current density information before correction from RAM 42 is stored. μP4 for writing density information
Add the density correction amount from 0 and modulate the corrected density information used to actually write the current rask,
It is comprised of an exposure amount adjustment means 46 that outputs an exposure amount electric signal for one line and an exposure timing electric signal.

The μP 54 receives the conveyance amount or conveyance speed information of the recording material 24 from the rotary encoder 38 constituting the conveyance amount detection means, calculates the conveyance amount to the exposure position, determines the exposure timing, and converts the exposure timing signal into the exposure amount. The light is transferred to the LED array 18 of the exposure head 12 via the adjustment means 46, causing the LED array 18 to emit light.

Furthermore, even though the recording material 24 is being conveyed to the correct exposure position, the memory of the LED array 18 of the exposure head 12 is
If the density information for a line has not been transferred, the conveyance amount or conveyance speed of the recording material 24 from the rotary encoder 38 +l! Based on the first report, the conveyance position deviation of the recording material 24 is detected, the interval between the previous rask and the rask to be written this time is calculated, that is, the scanning position deviation of the current rask is calculated, and this rask interval or scanning position is calculated. Sure,
Concentration information of the previous rask from RAM44, RAM45
Based on the density information of the rask to be written next time from , the density correction amount of the rask to be written this time is determined. The density correction amount determined by the μP 40 is added to the current original density before correction read from the RAM 42 in the exposure amount adjusting means 46 to determine the density to be written this time after correction, and the exposure amount adjustment for each pixel is The LED for each pixel of the LED array 18 of the exposure head 12 is modulated into a signal.
The exposure amount electric signal for one row of rask is transmitted to each LED.
Immediately after the data is transferred to the memory, each LED emits light. In the present invention, immediately after the LED array 18 emits light and the immediately preceding rask is written by exposure, the density data of each pixel for one row of the currently written rask stored in the RAM 42 is transferred to the exposure amount adjusting means 46. The data is transferred to the memory of each corresponding LED of the LED array 18 in the exposure head 12 via the. Each LE of the LED array 18 for one row of rask
It is preferable that D corresponds to each pixel, for example,
If the writing interval of one pixel is 1/16 mm, the number of pixels required for A4 full size is 4752 pixels, and the corresponding number of LEDs is 4752. Normally, in an exposure apparatus using an exposure element array, after all the density data of pixels for one row of rask is transferred to the memory of each LED of the corresponding LED array 18, one row is exposed simultaneously or one row is sequentially exposed. ．． In the present invention, when the transfer of the density data is completed and the μP 40 comes to the correct exposure position based on the conveyance amount signal from the rotary encoder 38 of the conveyance means 14 after writing the previous rask, the LED array 18 An exposure timing signal is issued to cause one row of LED arrays 18 to emit light, thereby exposing the recording material 24 to write a rask. Therefore, even if the conveyance means 14 has uneven conveyance speed or irregularity in conveyance, a scanning position shift due to a conveyance position shift will not occur. Therefore, since the reproduced image has small or no deviation in rask interval, density unevenness does not occur.

By the way, in order to obtain reproduced images with high resolution, image quality, etc., it is preferable to increase the number of pixels per unit length, but as mentioned above, with a density of 16 pixels/mm and A4 size, 4752 LEDs Therefore, it takes time to transfer the density data of each pixel for one raster row from the RAM 42 to the LED array 18, and if the recording material 24 cannot be exposed even though it has been transported to the correct exposure position. occurs. In this case, the rask interval will inevitably shift. This will cause density unevenness.
Density correction is performed according to the rask interval.

The density correction method, that is, the exposure amount adjustment method performed in the image exposure apparatus according to the present invention will be described below with reference to FIG. As shown in FIG. 3(a), the immediately preceding raster 48
a, raster 48b to be written this time, and raster 4 to be written next time
8c are at equal intervals, no density correction or exposure amount adjustment is performed. For example, raster 48a. 48b, 4
If the densities to be written by Kikure 8c are the same, the exposure amounts will also be the same, and the densities actually written will also be the same. However, as shown in FIG. 3(b), if the raster interval between the immediately preceding raster 48a and the current raster 48d is close, and the interval between the raster 48d and the next raster 48e is far, then the interval and the raster 48a. Depending on the density of 48d and 48e, the density of the raster 48d becomes lighter than the density that should originally be written, and the exposure amount is corrected and the exposure amount is adjusted so that the density of the next raster 48e becomes darker than the density that should originally be written. . Conversely, as shown in FIG. 3(c), if the interval between the immediately preceding rask 48a and the current rask 48f is large, and the interval between the current rask 48f and the next rask 48g is small, the density of the raster 48f will change. is increased;
The density of raster 48g is decreased.

For example, the density that should be written by Kiri is raster 48a to 48g.
Assuming that the corresponding rusks are equal, the relationship between the actually written densities is as follows.

D 4aa < D < ab , D 45 @ > D
4scD a6t > D 4ab + D 4at
< D 48C Here, DR indicates the density of raster R. In the image exposure apparatus shown in FIG.
Beam intensity of 0. OtmW, beam diameter 70x90μm2
Monochromatic exposure was performed with a raster bit of 60 μm and a color density of 0.8.

Here, as shown in Fig. 3(a), the rask interval is set to 10
When it is set to 0%, the raster spacing becomes as shown in FIG. 3(b), and the spacing between raster 48a and raster 48d is 99%, and the spacing between raster 48d and raster 48e is 101%.
If each rask is written at a position such that The density was uneven.

Therefore, in the image exposure apparatus 10 of the present invention, in order to perform density correction, the beam intensity is set to 98% in order to decrease the writing exposure amount of the raster 48d, and the beam intensity is set to 98% in order to increase the writing exposure amount of the raster 48e. When the exposure amount was adjusted to 102%, the density change was 0.02%.
9 (P-P), and the density unevenness was reduced by half.

As described above, in the present invention, the rask interval is adjusted by adjusting the intensity of the light beam of the light source in accordance with the rask interval, that is, the deviation in the main scanning line interval or the scanning position deviation. may be appropriately determined depending on the type of light source, beam diameter, etc.

In the examples shown in FIGS. 1 and 3, the density correction amount for the current writing raster 48b is calculated from the scanning position shift or rask interval, the immediately preceding raster 48a, and the next writing raster 48c. , may be calculated only from the scanning position shift or the rask interval. Furthermore, in the example shown in FIG. 1, the μP 40 determines the exposure timing and the density correction amount, and the exposure adjustment means 46 determines the current writing density, but the exposure adjustment means 46 is not provided. Alternatively, the exposure timing and exposure density may be controlled only by the μP 40. Although the exposure apparatus according to the present invention has been described using the monochrome exposure apparatus shown in FIG. 1 as a representative example, the present invention is not limited to this, and may be a color exposure apparatus that exposes color images. .

In the color exposure apparatus of the present invention, the configuration of the exposure head 12 shown in FIG. If density data for colors is to be controlled, the transport means 15 shown in FIG. 1 may be used. The color exposure element array only needs to have three to four color exposure elements in a cell for one pixel. For example, in the case of three colors, a light-emitting type exposure element array may be one in which light-emitting elements of three wavelengths corresponding to the three primary colors are bundled in a cell for one pixel and arranged in an array. The light emitting elements of these three primary colors may be caused to emit light accordingly.

In addition, in the case of a non-emissive type exposure element array, three primary color filters are movably arranged directly below each exposure element between the exposure element array and the light guide, and the filters are moved in and out at the same time as the exposure elements are exposed. Alternatively, three exposure elements may be bundled in a cell for one pixel, and filters for each of the three primary colors are fixed directly below each exposure element, and the three exposure elements may be configured according to image information. You can configure it so that it can be used differently. Further, the present invention can be modified as appropriate depending on the image recording device that can be used with the above-described exposure device. Further, such an image recording device may be a color or monochrome copying device, but may include an image reading section.
A color or monochrome image processing device that records a color or monochrome image by receiving color or monochrome image information processed by a compatible image processing device, even if it is an image from a computer, video, or optical disk. It may be a monochrome printer. Further, the recording material used may be either a photosensitive drum or a color or monochrome photosensitive material as described above. Therefore, the image recording device to which the present invention can be applied may be either color or monochrome, but for example, Japanese Patent Application No. 63-241-55 filed by the present applicant
In addition to the image recording device disclosed in No. 2, electrophotographic image recording devices, silver salt photographic image recording devices, thermal transfer image recording devices, inkjet image recording devices, laser printers, laser copying devices, video printers, Other examples include video copying devices and image recording devices using various photosensitive materials, such as light-sensitive pressure-sensitive photosensitive materials, photosensitive resin materials, and the like.

Although the exposure apparatus according to the present invention is basically configured as described above, the present invention is not limited to this, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course. Effects of the Invention> As described in detail above, according to the present invention, the conveyance amount of the recording material by the conveyance means is detected, and the exposure timing of the exposure element array of the recording material is determined based on the conveyance amount signal. By controlling this, even if uneven conveyance or positional deviation of the conveying means occurs, exposure can always be performed at the correct exposure scanning position, so the intervals between the main scanning lines (rusks) written on the recording material can be made equal. Therefore, it is possible to eliminate density unevenness caused by the pitch unevenness of the rask interval, and therefore, it is possible to obtain a reproduced image of good quality without density unevenness, whether it is color or monochrome.

Further, according to the present invention, in order to improve resolution and image quality,
Especially in color images, when the number of pixels in one row increases and the image density data of each pixel cannot be transferred to the memory of the exposure element array in time, the recording material may pass through the correct exposure position. , the scanning position shift of the main scanning line, that is, the rask, that occurs until the transfer of density data to the memory is completed is calculated, and the exposure amount is adjusted so that the density of the rask becomes darker or lighter depending on the distance between the rask. The density unevenness caused by the scanning position shift can be easily canceled out without using an expensive high-precision optical system or conveyance system, and a reproduced image with good image quality and no density unevenness can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective explanatory view including a control system of an embodiment of an exposure apparatus according to the present invention. FIG. 2a is a cross-sectional view of another embodiment of the exposure device used in the exposure apparatus of the present invention, and FIG. FIG. 3 is an explanatory diagram showing a completed rask (on the main scanning line). FIG. 4 is an explanatory diagram showing a rask defined by a conventional image exposure apparatus. Explanation of symbols 10...Exposure device, 12...Exposure head, 18...LED array 20...Light guide, 22, 22a, 22b--Light beam, l4...Transporting means, 16- ...Control unit, 24...Recording material, 26...Main scanning line (rusk), 30, 31, 32, 33...Roller, 34...Belt, 36...Drive source, 38. ...Rotary encoder, 40...Microprocessor (μP), 42, 44,
45...RAM, 46...Exposure amount adjustment means, 48a, 48b, 48c, 48d, 48e, 48f, 4
8g... Rusk, 50... Exposure head, 52... Housing, 54... Light source, 56... Liquid crystal cell array, 58... Cylindrical lens, 59... Light guide, 60a1 60b. ... Glass substrate, 61... Sealing layer, 62... Liquid crystal, 64a, 64b... Polarizing plate, 66, 68... Transparent electrode, 70... Light shielding layer, 72a, 70b... Liquid crystal alignment film F I G. 2b

Claims (1)

[Claims] (1) A linear exposure element array for exposing a recording material, a conveyance means for conveying the recording material in a direction substantially perpendicular to the arrangement direction of the linear exposure element array, and a conveyance amount of the conveyance means. An exposure apparatus comprising: a conveyance amount detection means for detecting the conveyance amount; and a control means for controlling the exposure timing of the exposure element array based on the conveyance amount signal detected by the conveyance amount detection means.