JP2003011429A - Solid scanning type optical write apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solid scanning type optical write apparatus which can effectively correct a variation of quantities of transmission light for each optical shutter chip, can obtain high-quality images, and can be made compact and highly reliable. SOLUTION: The solid scanning type optical write apparatus is provided with an optical shutter module 6 in which a plurality of optical shutter chips 12 formed of PLZT and having a plurality of optical shutter elements formed in at least one array are arranged in a horizontal scanning direction X, and a back light 30 including an LED array for sequentially switching and irradiating R, G and B lights to optical shutter elements. A quantity of emission light of the LED array as a light source can be corrected by controlling a current value. The quantity of transmission light for each optical shutter element is detected, and the quantity of emission light of the LED array is corrected for each optical shutter chip based on the detected result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state scanning optical writing device, and more particularly to a solid-state scanning optical writing device for forming a full-color image using a plurality of optical shutter chips made of a material having an electro-optical effect. Regarding

[0002]

2. Description of the Related Art Conventionally, PLZT, LiNbO ₃ which is a material having an electro-optical effect has been used as a solid scanning type optical writing device for forming an image on a printing paper or a film using a silver salt sensitive material.
It is known that a plurality of light modulation areas (light shutter elements) are formed on an optical shutter chip made of, and the chips are arranged in an array to control light on / off.

The principle of this optical writing device is as shown in FIG. That is, by applying a voltage to the pair of electrodes 15 and 16 provided on the optical shutter chip 12 made of PLZT to generate an electric field, birefringence is generated in the PLZT, and optical modulation is performed through the polarizer 5 arranged in the preceding stage. The light incident on the area (optical shutter element) 13 is polarized by 90 °, and the emitted light passes through the analyzer 7. On the other hand, when no electric field is generated, the light passing through the polarizer 5 passes through the optical shutter element 13 without being polarized and is blocked by the analyzer 7.

In such an optical shutter element 13, the maximum amount of transmitted light can be obtained when the incident light is polarized by 90 °, and the applied voltage at this time is called a half-wave voltage. It is driven by voltage. The gradation of the image is reproduced by modulating the time for applying the half-wave voltage for each element 13, that is, by performing pulse width modulation.

FIG. 10 shows a schematic structure of a conventional solid-state scanning optical writing device. This optical writing device includes a light source 1 such as a halogen lamp, a heat insulating filter 2, and a color filter 3.
The optical fiber array 4, the polarizer 5, the optical shutter module 6, the analyzer 7, and the imaging lens array 8.

The color filter 3 has R, which are the three primary colors of light,
A disk-shaped rotating body having three filter portions for transmitting G and B respectively.
It is rotationally driven in synchronization with the writing of the line.

Further, in the optical shutter module 6, the optical shutter chips 12 are arranged on a support substrate 11 along one printing line (main scanning direction X), and the drive ICs 2 are arranged on both sides thereof.
0s are arranged side by side, and a large number of optical shutter elements 13 corresponding to one pixel are formed in each chip 12 in the main scanning direction.

As described above, when the voltage applied to each optical shutter element 13 is turned on and off, the transmitted light is turned on and off, and the analyzer 7
The light emitted from the lens is imaged on a photosensitive material (not shown) via the imaging lens array 8. The optical shutter element 13 is ON / OFF controlled line by line based on the image data (main scanning), and a two-dimensional image is formed on the photosensitive material by this main scanning and the movement of the photosensitive material in the arrow Y direction (sub scanning). Is formed. Also,
One line is exposed with light separated by the color filter 3 for each of R, G, and B colors.

[0009]

In the solid-state scanning type optical writing device, the optical shutter module 6 mainly includes a plurality of optical shutter chips 12 in order to secure the number of pixels of one line of size A3, A4 or the like. They are arranged in the scanning direction X. For example, when the 512-pixel optical shutter element 13 is formed in one chip, 400 d
To print 5120 pixels of pi on a 12-inch line, it is necessary to arrange 10 chips 12. In addition,
The number of optical shutter elements 13 that can be formed in one chip is PLZ.
It is determined by the size of the T-wafer, the specifications of the processing machine, and the like.

As described above, when a plurality of chips are incorporated into one module, the transmitted light amount characteristic varies from chip to chip, and therefore, an exposure image may have a density difference or a color difference for each chip. I had a problem.
FIG. 11 shows a transmitted light amount distribution in one line using ten chips.

In the case of chips made of PLZT, the cause of variations in the amount of transmitted light from chip to chip is due to subtle variations in composition between manufacturing lots of PLZT wafers, variations in processing dimensions of openings, and the like. In order to correct these variations in light quantity, conventionally, a drive voltage is controlled to an optimum value for each chip, or chips having similar characteristics are grouped to form a module. However, a high-voltage drive circuit is required to control the drive voltage for each chip,
Grouping chips having similar characteristics lowers the manufacturing yield, and any of the methods causes an increase in cost.

Further, in the structure in which the three primary colors of R, G and B are switched by the rotary color filter 3, there is a problem in the reliability of the mechanical structure including the movable part, it is necessary to take measures to suppress noise, and optical transmission is required. Since the optical fiber array 4 is installed as a path, there is a problem that the device becomes large.

Therefore, it is an object of the present invention to effectively correct variations in the amount of transmitted light for each optical shutter chip to obtain a high-quality image, and to achieve miniaturization and high reliability in solid-state scanning. Type optical writing apparatus.

[0014]

In order to achieve the above object, the solid-state scanning optical writing device according to the first invention comprises an optical shutter module, a backlight means, a light quantity detecting means, and a control means. There is. The optical shutter module includes a plurality of optical shutter chips formed in at least one row and formed of a material having an electro-optical effect, and arranged in the row direction of the elements, and a drive circuit for driving the elements. Is installed. The backlight unit includes a light emitter that sequentially switches and irradiates light of three primary colors, R, G, and B, onto the optical shutter element, and the light emitter can correct the amount of light emitted. The light amount detecting means detects the amount of transmitted light for each optical shutter element, and the control means corrects the light emitting amount of the light emitter for each optical shutter chip based on the detection result of the light amount detecting means.

Also, in the solid-state scanning optical writing device according to the second invention, the transmitted light amount of each of the optical shutter module, the backlight means, and each optical shutter element is detected, and the emitted light amount of the light emitter is detected. The storage unit stores a correction value for correcting each shutter chip, and a control unit that controls the backlight unit by referring to the correction value.

In the solid-state scanning optical writing devices according to the first and second aspects of the present invention having the above-described structure, the amount of light emitted from the light emitter is corrected for each color on a chip-by-chip basis. Can be effectively corrected, and a high-quality image with good density difference and color difference can be obtained. LE is a light emitter that can correct the amount of light emitted on a chip basis.
A D array, an LE light emitter bar, a phosphor bar, etc. can be used, and the amount of light emitted from this kind of light emitter can be easily controlled by controlling the current value. No circuit needed. In addition, this type of light emitter does not require a rotary color filter or an optical fiber array, which eliminates the concern about mechanical reliability and enables downsizing of the device.

That is, in the first aspect of the invention, the light amount detecting means is mounted, the amount of transmitted light is detected in real time, and the result is fed back to the writing process. In the second invention, the light amount detecting means is not mounted, and for example, the transmitted light amount is detected at the shipping stage of the device and is stored in advance in the storage means as a correction value for each optical shutter chip, and is read during the writing process. Controls the backlight means.

In particular, in the first invention, an optical sensor for measuring the amount of transmitted light of each optical shutter element, and a processing circuit for sampling the measurement value of the optical sensor and detecting the average amount of transmitted light of one optical shutter chip. It is preferable to use a light amount detecting means consisting of Also in the second aspect of the invention, the amount of transmitted light of each optical shutter element can be measured using such a light amount detecting means.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a solid-state scanning optical writing device according to the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a first embodiment of a solid-state scanning optical writing device according to the present invention. This optical writing device includes a polarizer 5 in front of an optical shutter module 6.
The backlight 30, the light diffusion sheet 35, and the mirror integrator 36 are installed via the. The configurations and operations of the optical shutter module 6, the polarizer 5, the analyzer 7, and the imaging lens array 8 are the same as those of the conventional optical writing device shown in FIG. 10, and a duplicate description will be omitted.

The backlight 30, as shown in FIG.
A red light emitting LED array 31R, a green light emitting LED array 31G, and a blue light emitting LED array 31B are arranged on a substrate 31, and each LED is driven by a current control circuit 32. FIG. 1 shows an example in which seven chips 12 are arranged in the main scanning direction X, and in response to this, the control circuit 32 divides each LED array 31R, 31G, 31B into seven areas. R, G, B for each area
It is possible to correct the amount of emitted light by controlling the amount of current for each.

The relationship between the amount of emitted light and the drive current of the LED generally shows the linear characteristic shown in FIG. 5, and a desired amount of emitted light can be obtained by controlling the drive current. In the present embodiment, the amount of transmitted light that tends to vary among the chips 12 is made uniform by utilizing such light emitting characteristics of the LEDs as described below.

Each of the LED arrays 31R, 31G, 31B is sequentially switched and controlled to emit light at a 1/3 cycle of the printing cycle of one line of the image, and the emitted light passes through the light diffusion sheet 35 and the mirror integrator 36. Each chip 12
Each time, linear light is formed that is substantially flat in the main scanning direction, and illuminates the optical shutter element 13 through the polarizer 5.

The linearly polarized light incident on the optical shutter element 13 is turned on and off as described with reference to FIG. FIG. 7 shows the relationship between the driving voltage for each of R, G, and B and the amount of transmitted light. Further, FIG. 8 shows a difference in average value of transmitted light amounts of one chip a and another chip b in G light. In the present embodiment, the difference ΔG in the amount of transmitted light when driven with a half-wave voltage is adjusted by correcting the amount of light of the backlight 30.

Therefore, in the first embodiment, as shown in FIG. 3, a calibrator 40 for detecting the amount of transmitted light of each optical shutter element 13, an optical signal processing circuit 45, and a digital processing circuit 46 are installed. . Calibrator 40
The optical sensor 41 can travel along the guide 42 in the main scanning direction X at a predetermined speed in front of the imaging lens array 8. The optical sensor 41 measures the amount of transmitted light for each optical shutter element 13 in a state where each LED is driven by a reference current for each of R, G, and B lights. At this time, each element 13 is driven based on the image data of the same gradation.

As a control unit of the optical writing device, FIG.
, The central processing unit 51, the sensitive material data ROM 5
2, calibration data RAM 53, RA for image
The data processing circuit 5 includes an M54 and a data processing circuit 55.
Reference numeral 5 is connected to a computer 60 that outputs image data and the like via an interface 56.

The transmitted light amount for each element measured by the optical sensor 41 is amplified and integrated by an optical signal amplification and integration circuit 45a, and further sampled as a transmitted light amount for each chip 12 by a sample hold circuit 45b. It is an average value. This sampling data is transferred to the central processing unit 51 via the A / D conversion circuit 47. The output values of the high-voltage driver that drives the optical shutter element 13 at the time of measuring the transmitted light amount are the same, and a light amount difference occurs in the sampling data due to the variation in the characteristics of each chip 12.
This light amount step is as shown in FIG.

The central processing unit 51 calculates a correction value for each chip 12 based on the amount of transmitted light detected for each chip 12 so as to make the light level difference uniform, and the RAM 5
Store in 3. When actually forming an image, the central processing unit 51 refers to the correction value stored in the RAM 53, and transfers the current value in which the color balance of R, G, B is corrected for each chip 12 to the current control circuit 32. LED array 3
Lighting control is performed on 1R, 31G, and 31B.

By such lighting control, the chip 12
It is possible to effectively correct the variation in the amount of transmitted light that differs for each. FIG. 6 shows the transmitted light amount distribution in one line after correction. FIG. 11 shows the distribution of the amount of transmitted light after correction shown in FIG.
Comparing with the distribution of transmitted light amount before correction shown in (4), it is clear that the light amount variation in each chip is uniform.

Each optical shutter element 1 in one chip
Although a slight variation in the amount of transmitted light (high frequency ripple) also occurs for each of the three types, this type of ripple can be finely adjusted by pulse width modulation control that modulates the drive pulse width for each element 13. Such fine adjustment is performed using the light amount data for each element 13 measured by the optical sensor 41.

Strictly speaking, even if the amount of light emitted from the backlight 30 is corrected on a chip 12 basis, the light passes through the light diffusion sheet 35 and the mirror integrator 36, so that near the boundary between adjacent chips, The light from the LED arrays that illuminate adjacent areas will mix. As described above, the elements 13 located at the ends of the chip 12 may be individually fine-tuned by pulse width modulation control using the light amount data of each element 13 measured by the optical sensor 41.

Further, since the photosensitive material which is a recording medium also has individual photosensitive characteristics with respect to wavelengths, such characteristics are stored in the ROM 52 and added to the correction value of the emitted light amount obtained as described above. If the arithmetic processing is performed, it is possible to obtain an image having a more preferable color balance.

In addition to the LED array, an EL light emitter bar or a phosphor bar may be used as the light emitter of the backlight 30, depending on the sensitivity of the photosensitive material of the recording medium.

(Second Embodiment) In the second embodiment, the calibrator 40 shown in the first embodiment and the circuits 45, 46 and 47 associated therewith are not mounted, and devices other than these non-mounted devices are not mounted. The configuration is similar to that of the first embodiment.

In the second embodiment, when the solid-state scanning optical writing device is mounted on a printer or the like, or when it is shipped, the amount of light transmitted through each optical shutter element is detected in advance by a separately installed calibrator 40. A correction value for each shutter chip is calculated and stored in the storage means. In this case, a ROM may be used as a storage means instead of the RAM 53. When actually forming an image, the central processing unit refers to the correction values stored in advance in the ROM, and turns on the LED array with a current value in which the color balance of R, G, B is corrected for each optical shutter chip. Will be in control.

(Other Embodiments) The solid-state scanning optical writing device according to the present invention is not limited to the above-mentioned embodiment, but can be variously modified within the scope of the invention.

For example, the detailed structure of the optical shutter chip and the detailed shapes of the common electrode and the individual electrode are arbitrary. As the material having the electro-optical effect, various materials other than PLZT can be used.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a solid-state scanning optical writing device according to the present invention.

FIG. 2 is a schematic explanatory diagram of a backlight used in the optical writing device.

FIG. 3 is a schematic explanatory diagram of a calibrator used in the optical writing device.

FIG. 4 is a block diagram showing a control unit of the optical writing device.

FIG. 5 is a graph showing a light emission amount with respect to a drive current of an LED which is a light source of the backlight.

FIG. 6 is a graph showing a transmitted light amount distribution of the optical shutter element after the light amount is corrected in the present invention.

FIG. 7 is a graph showing the relationship of the amount of transmitted light with respect to the drive voltage in the optical shutter element for each of R, G, and B.

FIG. 8 is a graph showing variations in transmitted light amount (average value) with respect to drive voltage in two optical shutter chips.

FIG. 9 is an explanatory diagram showing an operation principle of a solid-state scanning optical writing device using PLZT.

FIG. 10 is a perspective view showing a conventional solid-state scanning optical writing device.

FIG. 11 is a graph showing a transmitted light amount distribution of an optical shutter element (before light amount correction) in a conventional optical writing device.

[Explanation of symbols]

6 ... Optical shutter module 12 ... Optical shutter chip 13 ... Optical shutter element 30 ... Backlight 31R, 31G, 31B ... LED array 35 ... Light diffusion sheet 36 ... Mirror integrator 40 ... Calibrator 41 ... Optical sensor 45b ... Sample and hold circuit 51 ... Central processing unit X ... Main scanning direction

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C162 AE12 AE23 AE28 AE47 AE77                       AF20 AF21 AF59 AF70 AF84                       FA09 FA10 FA33                 2H079 AA02 BA02 CA22 DA04 KA18                 5C051 AA02 CA08 CA11 DA03 DB02                       DB22 DB24 DB26 DB29 DB31                       DC02 DC04 DC05 DC07 DE26                       DE30 EA01                 5C072 AA03 BA01 BA13 BA17 HA01                       HA20 HB04 QA14 XA04                 5F041 AA10 DC83 EE25 FF13

Claims (6)

[Claims] 1. A drive circuit for driving a plurality of optical shutter elements, the plurality of optical shutter chips being formed in at least one row and made of a material having an electro-optical effect, arranged in a row direction of the elements, and driving the elements. An optical shutter module provided with the light shutter element, and a backlight unit that includes a light emitter that sequentially switches and irradiates the light of the three primary colors, R, G, and B, to the light shutter element, and the light emitter is capable of correcting the amount of emitted light. A light amount detecting unit that detects the amount of transmitted light for each optical shutter element; and a control unit that corrects the light emitting amount of the light emitter for each optical shutter chip based on the detection result of the light amount detecting unit. Characteristic solid-state scanning optical writing device. 2. A plurality of optical shutter chips, which are formed in at least one row and are made of a material having an electro-optical effect, are arranged in the column direction of the elements, and a drive circuit for driving the elements. An optical shutter module provided with the light shutter element, and a backlight unit that includes a light emitter that sequentially switches and irradiates the light of the three primary colors, R, G, and B, to the light shutter element, and the light emitter is capable of correcting the amount of emitted light. A storage unit that stores a correction value that detects the amount of transmitted light for each optical shutter element and corrects the amount of light emitted from the light emitter for each optical shutter chip; and controls the backlight unit with reference to the correction value. A solid-state scanning optical writing device comprising: a control unit. 3. The light-emitting body is a linear light source along the arrangement direction of the optical shutter chips, and the amount of emitted light of R, G, B can be corrected for each optical shutter chip. The solid-state scanning optical writing device according to claim 1 or 2. 4. The light emitting body is an L which emits R, G and B lights arranged along an arrangement direction of the optical shutter chip.
ED array, R, G, B for each optical shutter chip
2. The amount of emitted light of can be corrected.
Alternatively, the solid-state scanning optical writing device according to claim 2. 5. The solid-state scanning optical writing device according to claim 1, further comprising a light diffusing member provided between the backlight unit and the optical shutter module. 6. The light amount detecting means includes an optical sensor for measuring the amount of transmitted light of each optical shutter element, and a processing circuit for sampling the measurement value of the optical sensor and detecting the average amount of transmitted light of one optical shutter chip. 2. The solid-state scanning optical writing device according to claim 1, comprising: