JPH05124261A - Optical writing device - Google Patents

Abstract

PURPOSE:To provide an optical writing device having light emitting elements arranged in an array and a driving system capable of heightening resolution substantially. CONSTITUTION:To make it possible to change timing of light emission in accordance with image information of picture element around picture element to be written. That is, there is provided a control circuit wherein an emitting time for 1 line is divided into plurality of time segments, correction data corresponding to this divided emission/non-emission are stored in shift registers (71A-71D) and latch circuits (72A-72D) at every division, the latch circuits are selected by a timing generating circuit, so as to take out information of the emission/non-emission for every segment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device for converting image information to be recorded into an optical signal and writing it on a photoconductor, and more particularly to an optical writing device having light emitting elements arranged in an array.

[0002]

2. Description of the Related Art In recent years, high-speed, high-quality output devices for various information devices have been demanded. In order to meet such demands, image information to be recorded is converted into optical signals and photoconductors are converted. The method of writing in is becoming popular.
As the optical writing device used here, a device combining a laser with a rotating polyhedral mirror, a galvanometer mirror, or the like, or a device using an optical shutter array such as liquid crystal,
An array light source such as a light emitting diode array, a plasma discharge element array, or an electroluminescent element array, a CRT
And a combination of optical fibers are used. However, these optical writing devices cannot be said to be sufficient in terms of reliability, cost, occupied volume, and the like, and research on a new type of optical writing device is underway. Here, one of them will be described by taking as an example the one to which the principle of the fluorescent display tube is applied.

An optical writing device applying the principle of a fluorescent display tube is based on a direct heating type triode vacuum tube structure. FIG. 9 shows a plan view of the example, and FIG. 10 shows a sectional view thereof.
This optical writing device 81 constitutes a vacuum container with a glass substrate 82 and a face glass 89 adhered onto the glass substrate 82 with a low melting point glass. An anode electrode 83 is formed on the glass substrate 82, and phosphor dots 84 are applied on the anode electrode 83 by electrodeposition. As shown in FIG. 9, a large number of these anode electrodes 83 and phosphor dots 84 are arranged in rows. Further, above the anode electrode 83, a cathode filament 87, which is an electron source in which an electron emissive material is applied to a fine wire of tungsten, is stretched, and between the cathode filament 87 and the anode electrode 83, a metal is provided. The mesh-processed grid electrode 86 is held at a constant distance from the anode electrode 83 and the cathode filament 87.

Further, the anode electrode 83 is divided into odd-numbered dots and even-numbered dots, and the driving IC is arranged on the glass substrate 82 by wiring (not shown).
It is connected to 88. The grid electrode 86 and the cathode filament 87 are connected to an external power source by a wiring (not shown) so that a predetermined voltage is applied. The electrical configuration of this embodiment is shown in the block wiring diagram of FIG.

The optical writing device 81 is arranged so as to face the photoconductor 90 with the rod lens 91 interposed therebetween.
The photoconductor 90 is conveyed by a drive mechanism 95 (not shown) in a direction perpendicular to the longitudinal direction of the optical writing device 81, that is, in the sub-scanning direction X.

The driving IC 88 comprises a shift register 97, a latch circuit 98, and a drive circuit 99, as shown in FIG. Further, the drive IC 88 has image data GD corresponding to image information to be written,
An odd clock signal OC as a control signal, an even clock signal EC, a latch signal LA, and a strobe signal ST for applying an anode voltage are added.

In the optical writing device having the above structure, an AC filament voltage FV is applied to the cathode filament 87. In FIG. 11, the filament voltage FV
Is an AC voltage, and a DC cutoff voltage KV is also applied so that the potential is always positive with respect to the ground potential. When the filament voltage FV is applied, the cathode filament 87 is heated, and thermoelectrons are emitted from the applied electron emitting material. The grid electrode 86 is applied with a positive grid voltage GV with respect to the cathode filament 87, the thermoelectrons emitted from the cathode filament 87 are accelerated, and part of the grid electrode 86.
The thermoelectrons passing through the grid electrode 86 are directed to the anode electrode 83.

Here, when a positive voltage is applied to the anode electrode 83 with respect to the cathode filament 87, the thermoelectrons passing through the grid electrode 86 reach the anode electrode 83 and become an anode current. At this time, the thermoelectrons stimulate the phosphor 84 applied to the anode electrode 83 to cause it to emit light. When a negative voltage is applied to the anode electrode 83 with respect to the cathode filament 87, the thermoelectrons that have passed through the grid electrode 86 cannot reach the anode electrode 83, and the phosphor 84 does not emit light.

Therefore, a driving IC arranged on the substrate 82
By 88, the voltage applied to the anode electrode 83 is selectively changed according to the image information to be recorded, and the emission / non-emission of the phosphor 84 is controlled.

As described above, the driving IC 88 has an odd clock signal O generated by a clock circuit (not shown).
C or an even clock signal EC is added (denoted as clock signal CL in FIG. 12). These clock signals CL are generated by dividing the reference clock signal, and as shown in FIG.
_An odd clock signal OC is added to ₁ , IC ₃ ... IC _2n-1 , and an even clock signal EC is added to even dot driving ICs ₂ , IC _4, ... IC _2n . These clock signals CL are applied to the shift register 97 in each IC, and the odd-numbered data signals of the image signal GD to be recorded based on the clock signals CL are odd-dot drive I
The even-numbered data signals are set to C ₁ and are set to the even driving IC ₂ , respectively.

IC ₁ for driving odd-numbered dots, IC ₃ ... IC
_2n-1, the even dot driving IC _2, IC ₄ ...... shift register 97 in the IC _2n are respectively connected to the cascade by repeating the above operations, the data in each IC
While shifting the registers of the shift register 97 inside, the overflowed data is transferred to the shift register 97 inside the next drive IC. When the image signal GD for one column is transmitted, the latch signal LA is sent to each IC all at once, and the contents of the shift register 97 of each IC are taken into the latch circuit 98. That is, one column of data is latched in the entire IC. Here, the strobe signal ST is applied to each IC, and the drive circuit 99 supplies a predetermined anode voltage to the anode electrode 83 according to the content of the latch circuit 98. As a result, the fluorescent substance 84 selectively emits light based on the image signal GD for one column.

The light emitted from the phosphor 84 passes through the face glass 89 and is output, and is imaged on the surface of the photoconductor 90 by the rod lens 91. Thereby, the image information for one column can be written on the photoconductor 90, and by repeating the above operation while moving the photoconductor 90,
Image information to be recorded can be written on the photoconductor 90.

On the other hand, in the output device of such information equipment, there is a strong demand for higher resolution, and it is necessary to develop a method for substantially increasing the resolution without significantly increasing the cost. There is.

For a combination of a rotating polyhedral mirror and a laser, a method has been proposed in which the resolution is substantially increased by controlling the laser emission intensity and the emission timing.

That is, in the case of a diagonal line which is almost vertical to the scanning direction of the laser, as shown in FIG.
The jagged edges of the edge are made inconspicuous by shifting the light emission timing, and in the case of diagonal lines that are nearly parallel to the laser scanning direction, the emission intensity is changed over two columns to make the edge inconspicuous.

[0016]

However, an LED including an optical writing device applying the principle of a fluorescent display tube is used.
In an optical writing device of a type having an array of light emitting elements such as an array or a liquid crystal shutter array,
The light emitting pitch in the array direction of the light emitting elements corresponding to the laser scanning direction is fixed. Therefore, the resolution cannot be substantially increased by the same method as described above.

The present invention has been made in order to solve the above-mentioned problems, and in an optical writing device of a type having a light emitting element array such as an optical writing device to which the principle of a fluorescent display tube is applied, the resolution is substantially reduced. It is an object of the present invention to provide an optical writing device that utilizes a driving method that improves the optical characteristics.

[0018]

In order to achieve this object, an optical writing device of the present invention is an optical writing device having a large number of light emitting elements arranged in an array, and is provided in accordance with neighboring pixel information. The light emission start timing and light emission time of each light emitting element are controllable.

[0019]

In the optical writing device of the present invention having the above-mentioned structure, it is possible to make the edge of an image jagged by changing the light emission start timing and light emission time of each light emitting element. It is possible to improve the resolution.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an optical writing device to which the principle of a fluorescent display tube is applied will be described with reference to the drawings.

First, the configuration of this embodiment will be described with reference to FIG.

The optical writing device 1 according to the present embodiment corrects based on the temporary storage circuit 11 for storing the image information of several columns of the image information supplied from the external device, and the information stored in the temporary storage circuit 11. Correction signal generation circuit 1 for generating information
2. The control circuit 13 controls the light emitting element array 14 based on the correction signal generated by the correction signal generating circuit 12, and the light emitting element array 14.

The correction signal generating circuit 12 is, for example, Japanese Patent Application Laid-Open No.
A correction signal is generated by a known correction means as disclosed in Japanese Patent Laid-Open No. 112966.

An example will be described. First, the image information of M × N dots around the pixel to be corrected is read from the temporary storage circuit 11. The correction signal generating circuit 12 compares this image information with a pattern registered in advance. If there is a pattern that matches the registered pattern, correction data corresponding to that pattern is generated. When a plurality of patterns match, the logical sum of the correction data is used as the correction data. If there is no match with the registered pattern, the standard data 41 or 50 is output according to the image information before correction.

The correction data are 41 to 50 as shown in FIG.
There are 10 types. Of these, 41 and 50 are standard light emission and non-light emission patterns. Each correction data is shown in Figure 3.
As shown in, the emission time of one line is 33%, 50%, 6
It is divided into 4 areas of 7% and 100%, and the light emission of each area
It is generated without light emission. Therefore, these correction data can be expressed by 4-bit binary data such as 41 correction data for 1111 and 42 correction data for 1110 and 43 correction data such as 0111. Here 46,
The correction data of 47, 48, 49, 50 are 100%, 83%, 66%, 34% of the light emission time of one line,
It emits only 12% and 0%. By sequentially changing the emission intensities of the adjacent columns using these correction data, for example, when printing a diagonal line that is nearly parallel to the array direction of the light emitting elements, the edges are marked as shown in FIG. It can be corrected so that it does not hit.

Further, since the correction data of 42 and 43 emit light for 67% of the upper or lower time, and 44 and 45 emit light for the 33% of lower or upper time, 44 and 42,
Or by combining 43 and 45 up and down,
It is possible to shift the dot position up or down by a third. Therefore, by using these correction data, for example, it is possible to perform correction so that the position of a shaded line close to the vertical direction in the light emitting element arrangement direction is not noticeable at the edge as shown in FIG.

The correction data thus generated are sent to the control circuit 13. The control circuit 13 includes a shift register 71, a latch circuit 72, an AND gate array 73, an OR
It comprises a gate array 74, a drive circuit 75 and a timing generation circuit 76, and has a configuration as shown in FIG. Of these, the shift register 71 and the latch circuit 7
There are four sets of 2 corresponding to each of the 4-bit correction data, and the 4-bit correction data sent from the correction signal generating circuit 12 can be stored and latched for each column for each column. ..

The output of the latch circuit is the AND gate array 7
It is entered in 3. The output of the timing generation circuit 76 is connected to the other input of the AND gate array 73. As shown in FIG. 8, the timing generation circuit 76 outputs a timing signal corresponding to the division of the light emission time for correction shown in FIG. Therefore, each latch circuit 72
The data latched at is output only during the time when the light should be emitted. The output data is combined with the data latched in another latch circuit by the OR gate array and output to the drive circuit 75. 4 by the above operation
The correction data expressed in the form of bit binary data can be converted into a signal corresponding to the light emission time. Therefore,
The drive circuit 75 is driven by this signal to generate an anode voltage of the fluorescent display tube array, which is a light emitting element, and supplies it to the light emitting element 14. The light emitting element 14 causes each dot to emit light by the operation described in the section of the related art.

As described in detail above, by using the driving method of the present embodiment, it is possible to provide an optical writing device capable of substantially increasing the resolution in the optical writing device applying the principle of the fluorescent display tube. ..

The correction data and the method of creating the correction data are merely examples, and other methods may be used as long as they are correction methods by controlling the light emission time.

If an optical writing device compatible with high resolution is available, the number of pixels can be increased by performing interpolation by the correction signal generating circuit. Also in this case, the driving circuit having the configuration shown in FIG. 7 is used, and the interpolation data in the direction perpendicular to the array direction of the light emitting elements is shift register 71A for each column
The light is taken into 71B, 71C, and 71D, and the timing generation circuit sequentially emits light. By doing so, it becomes possible to increase the resolution of the input image information and write it.

Here, an optical writing device to which the principle of the fluorescent display tube is applied has been described as an example, but as the light emitting element, LE is used.
Even in an optical writing device using a light-emitting array of another type such as a D array or a liquid crystal shutter array, the drive circuit can be configured to output an appropriate voltage or current, and can be realized with a completely similar configuration. It is possible.

The present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention.

[0034]

As is apparent from the above description, in the optical writing device of the present invention, in the optical writing device using the light emitting elements arranged in an array such as an optical writing device to which the principle of the fluorescent display tube is applied, By controlling the light emission time based on the correction data generated based on the image information around each pixel and writing the information as a plurality of columns of information, it is possible to substantially improve the resolution.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of an optical writing device according to an exemplary embodiment of the present invention.

FIG. 2 is a flow chart for explaining the operation of a correction signal generation circuit.

FIG. 3 is a diagram for explaining a configuration of correction data.

FIG. 4 is a diagram for explaining types of correction data.

FIG. 5 is a diagram for explaining an example of correction when a horizontal line is printed.

FIG. 6 is a diagram for explaining an example of correction when a vertical line is printed.

FIG. 7 is a block diagram illustrating a configuration of a control circuit.

FIG. 8 is a timing chart for explaining signals output from the timing generation circuit.

FIG. 9 is a plan view for explaining the configuration of an optical writing device to which the principle of the conventional fluorescent display tube is applied.

FIG. 10 is a sectional view illustrating a configuration of a conventional optical writing device.

FIG. 11 is a block diagram for explaining an electrical configuration of a conventional optical writing device.

FIG. 12 is a drive IC used in a conventional optical writing device.
3 is a block diagram illustrating the configuration of FIG.

FIG. 13 is a diagram illustrating image correction used in an optical writing device that uses a conventional rotating polyhedral mirror and a laser.

[Explanation of symbols]

 12 correction signal generation circuit 13 control circuit 14 light emitting element 71 shift register circuit 72 latch circuit (temporary storage means) 75 drive circuit 76 timing generation circuit (column selection means)

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location G03G 15/04 116 9122-2H H01J 31/15 Z 8326-5E H04N 1/036 A 9070-5C 1/23 103 A 9186-5C

Claims (5)

[Claims] 1. A large number of light emitting elements are arranged in one row or a plurality of rows, and light emission / non-light emission of each light emitting element can be independently controlled based on bitmap image information supplied from the outside. The optical writing device has means for performing interpolation based on image information around pixels to be written, and temporarily storing image information for a plurality of columns generated by the interpolation, and selecting image information for the plurality of columns. An optical writing device having means for outputting. 2. A large number of light emitting elements are arranged in one row or a plurality of rows, and it is possible to independently control light emission / non-light emission of each light emitting element based on image information in a bitmap form supplied from the outside. An optical writing device, wherein the optical writing device is configured so that the light emission start timing and the light emitting time of the pixel to be written can be controlled based on the image information around the pixel to be written. 3. The optical writing device according to claim 1, wherein the light emission time of each pixel is divided into a plurality of time regions, and light emission / non-light emission of each time region is controlled. 4. Correction information is generated based on image information around a pixel to be written, and the correction information is a data string corresponding to light emission / non-light emission of each region of a time region obtained by dividing a light emission time into a plurality of times. The data string is held for each time region, and the light emission / non-light emission of each pixel is controlled by selectively outputting the data of each time region according to a predetermined time region. The optical writing device according to claim 2. 5. An optical writing device to which the principle of a fluorescent display tube is applied is used as a light emitting element.
The optical writing device according to 1.