JPS63119375A - Laser picture recorder - Google Patents

Abstract

PURPOSE:To prevent color-misalignment at write onto a photosensitive material independently of the deviation or sequence of beams by starting the write at a point of time after a prescribed time elapses after a laser beam crosses a horizontal synchronizing sensor. CONSTITUTION:When the R, G, B laser beams 10-12 cross the horizontal synchronizing sensor 1, a beam detection signal is sent to a synchronizing signal generating circuit 2 to obtain a horizontal synchronizing signal. Picture element clock generating circuits 3-3'' generate a picture element clock signal when respective horizontal synchronizing signal comes. The counter circuits 5-5'' count the picture element clock signal by the picture element number corresponding to the scanning distance between the horizontal synchronizing sensor 1 and the picture write start position on the photosensitive material 13 and output a count end signal. Picture write clock generating circuits 6-6'' generate a picture write clock and AOMs (ultrasonic optical modulators) 7-7'' use a color picture signal inputted separately to apply amplitude modulation to each laser beam at the point of time of receiving the picture write clock.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in color shift correction of three laser beams for each of three primary colors in a color laser image recording device.

(Prior Art) FIGS. 4 and 5 are diagrams showing the basic configuration of a conventional color laser printer. FIG. 4 shows a system using three lasers, a red laser 18, a green laser 19, and a blue laser 20, as laser light sources, which is called a three-tube system. The system shown in FIG. 5 uses one helium-cadmium (He-Cd) white laser 17 that outputs white laser light containing the three primary colors of red, green, and blue, and is called a single-tube system.

In the three-tube type, each color laser beam output from each laser is connected to an AOM (Acou
The laser beams of each color are modulated with color image signals by the ultrasonic optical modulators 16, 16' and 16'', and the modulated laser beams of each color are transmitted to the corresponding gicchroic mirrors 14 and 14, respectively. ', 14'', and is combined into one beam by aligning the optical axes at the time of reflection, passes through an optical system, and is scanned by a deflector to scan the photosensitive material 13. Photoforming a color image on a surface.

In the single-tube type, one laser outputs laser light of three primary colors, red, green, and blue, as a single beam.

However, the intensity modulation by color image signals of each color is
This must be done separately for each blue laser beam. Therefore, the microchroic mirrors 15, 15', and 15'' are used to separate the red, green, and blue laser beams. The configuration is similar to that of the three-tube type.

In this manner, in all conventional image recording apparatuses, three modulated laser beams of different colors are superimposed into one beam, and the same spot is irradiated onto the imaging plane.

Horizontal synchronization (H
horizontal-Synchron: 1I-8y
A sensor (beam detection means) 1 for nc, ) signals is arranged, and a synchronization signal generated from a detection signal output from this is used to determine the timing at which an image of one combined beam starts to be written. is taking.

FIG. 6 is a diagram showing this time relationship.

Figure (a) shows the output waveform of the horizontal synchronization sensor 1, and Figure (b) shows the output waveform of the horizontal synchronization sensor 1.
) is a scan synchronization signal obtained by shaping the waveform in Figure (a), and Figure (C) shows that image writing starts after a certain period of time To has elapsed from the scan synchronization signal, and image writing continues for a predetermined period of time. It shows.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional technology, it is difficult to completely overlap the three laser beams on the imaging plane. In order to completely overlap the three color beam spots on the imaging plane, the guichroic mirror 14 shown in FIGS. 4 and 5 is used.
, 14' and 14", it is necessary to completely overlap the three laser beams, and very strict precision is required. For example, if the spot diameter at the imaging plane is 80 μm, f Assuming that the focal length of the −θ lens is 200 u+, and the allowable color shift on the imaging plane is 1/4 dot, then the gyroic mirrors 14 and 14 in Figs. 4 and 5.
' and 14'' setting angle error is approximately 1/180 degree (
20 seconds), a high degree of machining accuracy is required for the installation mechanism, and a high degree of skill and man-hours are required for installation adjustment.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a laser image recording device that can correct the color shift of three color laser beams on an imaging plane with simple means and with high precision. It's about doing.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following means configuration. That is, the laser image recording device of the present invention is an image recording device that records a color image on a color photosensitive material by simultaneously scanning a plurality of laser beams separated in the scanning direction and each having a different wavelength in the separated state. , one or a plurality of beam detection means provided corresponding to the plurality of laser beams; upon receiving a beam detection signal from the beam detection means, waveform shaping is performed for each of the plurality of laser beams having different wavelengths; a synchronization signal generation circuit that outputs a scan synchronization signal; each of the scan synchronization signals;
the plurality of pixel clock generation circuits that receive a clock signal having a frequency that is an integer multiple of a preset pixel clock frequency and divide the frequency of the clock signal from the arrival point of each scanning synchronization signal to generate a pixel clock signal; and; upon receiving the pixel clock signal from each of the pixel clock generation circuits and counting a predetermined number of pixels,
the plurality of counting circuits that output a counting completion signal; an AOM driver that generates an image writing clock upon receiving the counting completion signal from each of the counting circuits and performs intensity modulation for each of the plurality of laser beams having different wavelengths; A laser image recording apparatus characterized by comprising: the plurality of image writing clock generation circuits that output the plurality of image writing clocks to the image writing clock;

(Function) Hereinafter, the function of the laser image recording apparatus of the present invention having the above-described configuration will be described.

The present invention is based on the premise that the laser beams of multiple colors are not combined into one beam, but that the laser beams of each of the multiple colors are separated in the scanning direction. Separation here refers not only to cases where the beam spots on the imaging plane are completely separated, but also to cases where some of them overlap each other, as long as the beam detection means can distinguish and detect them. shall be included. Hereinafter, for convenience of explanation, a case of three colors will be explained.

Now, the case where only one beam detection means is provided will be described. The image writing start position on the imaging surface of the photosensitive material must be the same for all three laser beams.

If the scanning speed of the laser beam is the same for all three laser beams, the time it takes for the laser beam to cross the beam detection means and reach the image writing start position is independent of the magnitude of the deviation between the three beams. All three beams will be the same. Therefore, by starting to modulate the AOM driver corresponding to each laser beam with the color image signal of that beam when a predetermined time has elapsed from the time when the beam detection means detects the passage of the beam, Since both beams start writing images from the same position, there will be no color shift in the image recorded on the photosensitive material even if the beams themselves are separated.

Next, a case will be described in which beam detection means are provided separately for each color of laser beam. In this case, since the positions of the beam detection means are different, the distance to the image writing start position is different, and the time from when the laser beam crosses the beam detection means to reaching the image writing start position is different. Become. Therefore, for each laser beam, the passage of the beam is detected by the beam detection means, and then A
By setting different predetermined times until the OM driver starts modulating with the color image signal, the three laser beams start writing from the same position.

In the case of one beam detection means, it outputs a detection signal every time a plurality of laser beams cross.

In the case of a plurality of color beams, a detection signal is output only when a beam of a pre-corresponding color crosses the light.

In either case, the detection signal is applied to a synchronization signal generation circuit, which outputs a waveform-shaped scanning synchronization signal for each color (wavelength) of the laser beam. The scanning synchronization signal for each color is sent to a pixel clock generation circuit provided for each color. A clock signal having a frequency that is an integral multiple of the pixel clock frequency is simultaneously applied to each of the pixel clock generation circuits from a stable oscillator or the like. Each pixel clock generation circuit divides the frequency of the clock signal from the time it receives each scan synchronization signal to generate a pixel clock signal. Note that the higher the frequency of this clock signal, the smaller the time difference between the scanning synchronization signal and the first signal of the generated pixel clock signal.

This pixel clock signal is sent to a counting circuit provided corresponding to each pixel clock generation circuit. The counting circuit outputs a counting completion signal when it counts the sent pixel clock signals by a preset number. The time for counting this preset number corresponds to the elapse of the aforementioned predetermined time.

Therefore, when the number of beam detection means is one, the setting values of all the counting circuits are the same.

On the other hand, if a beam detection means is provided for each color of the laser beam, the set numerical value of the counting circuit will also differ depending on the setting position.

The counting completion signal of each counting circuit is sent to the image writing clock generation circuit provided corresponding to each counting circuit, and the image writing clock generation circuit generates an image writing clock at the timing of the counting completion signal. death.

Output to AOM driver. The AOM driver starts amplitude modulation using the corresponding color image signal based on this clock signal, and outputs the modulated high frequency signal to the AOM. Even if there is a misalignment, writing on the photosensitive material will not occur because each beam starts from the same position.

The reason why there is room for color shift when writing on photosensitive materials is due to the time difference between the scanning synchronization signal and the first pixel clock signal, but the maximum value of this time difference is divided by the period of the pixel clock signal. It is the value divided by the frequency ratio, and the color shift of the pixel at that time is 1 divided by the frequency of one dot. That is, if the frequency division ratio is 8, it will be a 1/8 dot, and if the frequency division ratio is 16, it will be a 1/16 dot.

Therefore, if the frequency of the clock signal is set high and the division ratio is increased, the color shift caused by the above-mentioned time difference can be ignored.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a scanning situation of a beam having a color shift in the present invention, in which a horizontal synchronization sensor 1 for detecting a passing beam is provided at a position on the left side (left margin) facing the photosensitive material 13. , red (R) laser beam 1
o shows a situation in which a green (G) laser beam 11 and a blue (B) laser beam 12 start scanning sequentially across the horizontal synchronization sensor.

Now, when three laser beams of R, G, and B cross the horizontal synchronization sensor 1, a beam detection signal as shown in FIG. 3(a) is obtained from the horizontal synchronization sensor 1.

This beam detection signal is sent to the synchronization signal generation circuit 2, where the waveform is shaped to obtain the scanning synchronization signal shown in FIG. 3(b). Among these scanning synchronization signals, the signal marked with R is sent to the pixel clock generation circuit 3, the signal marked with G is sent to the pixel clock generation circuit 3', and the signal marked with B is sent to the pixel clock generation circuit 3. At the same time, the pixel clock generation circuits 3, 3', and 3'' are sent from the crystal oscillator 4 to an integral multiple (e.g., 8 times) of the preset pixel clock frequency. A clock signal with a frequency of 16x, etc.) is added.

The pixel clock generation circuits 3, 3', and 3'' divide the frequency of the clock signal to generate a pixel clock signal from when each horizontal synchronization signal arrives. Each of these pixel clock signals has a corresponding count. Circuit 5, same 5'
, 5". Each counting circuit counts the pixel clock signals by the number of pixels corresponding to the scanning distance between the horizontal synchronization sensor 1 and the image writing start position on the photosensitive material 13, and When the count expires, a counting completion signal is output and sent to the image writing clock generation circuits 6, 6', and 6'' corresponding to the counting circuits 5, 5', and 5'', respectively, to generate each image writing clock. Each circuit generates an image write clock,
The image write clock generation circuit of this embodiment calculates the AND of the count completion signal from the counting circuit and the pixel clock signal from the pixel clock generation circuit. The image writing clock is generated by this.Each AOM driver amplitude-modulates the high frequency signal for a certain period of time from the time when the image writing clock arrives, using a separately input color image signal. Figure 3 (
c) shows the time interval of image writing for each color. If there is one horizontal synchronization sensor, 1. =1. =1S.

When three horizontal synchronization sensors are used for each color, 1l, t2, and t3 are values corresponding to the scanning distances between each horizontal synchronization sensor and the image writing start position.

Compared to the case of one horizontal synchronization sensor, it is more troublesome to adjust the set value of the counting circuit, but a circuit for discriminating R, G, and B synchronization signals in the synchronization signal generation circuit is no longer necessary.

In addition, as a method to separate the three color beams into the three horizontal synchronization sensors, you can use something like a gicroic mirror, or you can use a filter that allows only the laser beams of each color to pass through. Good too.

(Effects of the Invention) As explained above, in the apparatus of the present invention, the scanning distance between the fixedly provided horizontal synchronization sensor (beam detection means) and the image writing start position on the photosensitive material is fixed. By focusing on the fact that the laser beam crosses the horizontal synchronization sensor and starting image writing after the time corresponding to the scanning distance has elapsed, the laser beam is able to avoid color shift between multiple primary color beams. Even if there are multiple beams, each beam will start writing after a certain period of time has passed after crossing the horizontal synchronization sensor, so as long as the horizontal synchronization sensor can separate and identify each beam, there will be no difference between the beams. Since image writing is started from a point at the same distance from the horizontal synchronization sensor, that is, from the same position, regardless of the size or order of the images, there is an advantage that color shift does not occur when writing on the photosensitive material.

Even when horizontal synchronization sensors are provided for each color, the time from when the horizontal synchronization sensor is crossed to when writing starts depends on the scanning distance between each horizontal synchronization sensor and the image writing start position. If set, the image writing start position on the photosensitive material will be the same for each beam, so there is an advantage that color shift will not occur.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure shows the scanning situation of a beam with color shift. Figure 3 shows the time relationship between the scan synchronization signal and the start of image writing. Figure 4 shows the conventional 3
FIG. 5 is a block diagram of a conventional single tube color laser printer, and FIG. 6 is a time relationship diagram of scan synchronization in the conventional device. 1...Horizontal synchronization sensor (beam detection means), 2
・・・・・・Synchronization signal generation circuit, 3.3', 3''・
...Pixel clock generation circuit, 4...Crystal oscillator, 5.5', 5#...Counting circuit, 6
．． 6', 6''... Image write clock generation circuit, 7.7', 7''... AOM driver, 8...
...Polygon, 9...F-θ lens,
10... Red laser beam, 11...
Green laser beam, 12...Blue laser beam, 13...Photosensitive material, 14.14'. 14'', 15.15', 15''... Guicroic mirror, 16.16', 16'' ------
-AOM, 17...Helium-Cadmium (H
e-Cd) white laser, 18... laser for red color, 19... laser for green color, 20.
...Laser for blue light. Agent Patent Attorney Yoshihiro Yahata → 6 Akira /) Huang & (The end of the row / The color of the color is broken and the person who walks with the wrong shoulder L Yu 2 The timid synchronized accompaniment and the mountain (1-1 person interview (14 hour performance) Part 3
Figure i+, /4', 14','-------Tychroic mirror night eva everyone
Figure 14, /4: /4. "tchi15twozuzu'・-1--・-
Figure 6: Inu Kei synchronization in Mysterious Rumor Hit Display of case 1985 patent application No. 132174
No. 2, Title of the invention Laser image recording device 3, Relationship to the amended person case Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name (127) Representative of Konishiroku Photo Industry Co., Ltd. Keio Ide 4, Agent Address: 192Den 0426-44-1808
Address: 25-16-6 Yokoyama-cho, Hachioji-shi, Tokyo Subject of amendment (1) “Claims” column of the specification (
2) "Detailed Description of the Invention" column of the specification (3) Drawing 1, claims In an image recording apparatus that records a color image on a photosensitive material, a plurality of beam detection means are provided corresponding to one or the plurality of laser beams; and upon receiving a beam detection signal from the beam detection means, a synchronization signal generation circuit that outputs waveform-shaped scanning synchronization signals for each of the plurality of laser beams having different wavelengths; each of the scanning synchronization signals and a clock signal having a frequency that is an integral multiple of a preset pixel clock frequency; and the plurality of pixel clock generation circuits that generate pixel clock signals by frequency-dividing the clock signal from the arrival point of each of the scanning synchronization signals;
receiving a pixel clock signal from each of the pixel clock generation circuits; a plurality of counting circuits that output a counting completion signal when counting a predetermined number of pixels; generating an image writing clock upon receiving the counting completion signal from each counting circuit; 1. A laser image recording apparatus comprising: a plurality of image writing clock generation circuits for outputting the plurality of image writing clocks to one light m-stage which performs intensity modulation for each of the plurality of laser beams. 2. Column "Detailed Description of the Invention" (1) Correct "corresponding" to "corresponding example" in the third line of page 3 of the specification. In line 5 of the same page, change “and 16″ to [and 16″
With a light modulation means such as (2) rAOM from page 6, line 20 to page 7, line 1 of the specification
"driver" is corrected to "light modulation means". (3) "rAOM driver" on page 8, line 7 of the specification is corrected to "light modulation means." In the 8th line of the same page, "modulate with a signal" is corrected to "modulate the laser beam with a signal". ``at the rAOM driver'' on lines 19 and 20 of the same page is corrected to ``light modulation means j. (4) Output to the rAOM driver on page 10, line 16 of the specification.The AOM driver is'' is corrected to "output to the light modulation means.The light modulation means". In the 17th line of the same page, "by the signal...amplitude" is corrected to "by the signal, light by the corresponding color image signal". Delete "output modulated high frequency signal to AOM" in line 18 of the same page. (5) "Driver" on page 13, line 12 of the specification is deleted. Delete "driver" in line 17 of the same page. "High frequency signal" in line 19 of the same page is corrected to "each laser beam." (6) "Driver" on page 16, line 11 of the specification is deleted. Figure 1 of the drawings attached to the 36 specification is replaced with Figure 1 attached to the written amendment of this procedure. Sanskrit example 0 leak 0 area of this understanding Figure 7 November 30, 1988 Dear Commissioner of the Patent Office /(,-・ 1. Indication of the case Patent application No. 132174 of 1985
No. 2, Title of the invention Laser image recording device 3, Relationship to the amended person case Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name (127) Representative of Konishiroku Photo Industry Co., Ltd. Keio Ide 4, Agent Address: 192Den 0426-44-1808
Address: 25-16-6, Yokoyama-cho, Hachioji-shi, Tokyo, Subject of amendment: Written amendment of procedures (voluntary) submitted on August 19, 1988.

Claims (1)

[Claims] In an image recording apparatus that records a color image on a color photosensitive material by simultaneously scanning a plurality of laser beams separated in the scanning direction and each having a different wavelength in the separated state, one or more laser beams are used. a plurality of correspondingly provided beam detection means; and a synchronization signal generator that receives a beam detection signal from the beam detection means and outputs a waveform-shaped scanning synchronization signal for each of the plurality of laser beams having different wavelengths. A circuit that receives each of the scan synchronization signals and a clock signal having a frequency that is an integral multiple of a preset pixel clock frequency, and divides the clock signal from the time point at which each of the scan synchronization signals arrives to generate a pixel clock signal. the plurality of pixel clock generation circuits that generate; upon receiving the pixel clock signal from each of the pixel clock generation circuits and counting a predetermined number of pixels;
the plurality of counting circuits that output a counting completion signal; an AOM driver that receives the counting completion signal from each of the counting circuits, generates an image writing clock, and performs intensity modulation for each of the plurality of laser beams having different wavelengths; A laser image recording apparatus comprising: the plurality of image write clock generation circuits that output the plurality of image write clocks to the plurality of image write clock generation circuits.