JPS58174968A - Method and device for optical scanning type image recording - Google Patents

Abstract

PURPOSE:To obtain a picture image which is uniform and has a high grade, by controlling the intensity of a scanning beam according to the surface potential of a photoreceptor. CONSTITUTION:A function generator 39 emits the signal of a prescribed level changing according to the lapse time from a timing detector 32 with the timing detected with said detector as a reference, that is, the signal corresponding to the potential in the part to be scanned of a photoreceptor SP just prior to the exposure thereof. Either of said signal or the signal obtained by amplifying the output of a potential detecting means 10 with an amplifier 40 is selected with a switch 31 and is inputted to a modulation driving circuit 38. A modulator 2 which modulates the laser light outputted from a laser generator 1 is controlled by the output of the circuit 38, and scanning is accomplished with a scanning optical system 6. The picture image which is uniform and has a high grade is thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light beam scanning type 11!2 recording method and apparatus, and particularly to a light beam scanning type image recording method and apparatus that can uniformly reproduce high-quality images on a relatively large screen. Regarding.

In light beam scanning image recording devices that reproduce images on a relatively small screen, a charger, a charger,
An exposure section and a developing device are arranged, and charging, exposure, and development are performed in accordance with the sub-scanning speed of the scanning exposure of the screen. That is, the leading edge and trailing edge of the screen to be scanned and exposed are subjected to charging, exposure, and development processes at the same time intervals. Therefore, images of the same quality can be obtained at both the leading end and the trailing end.

On the other hand, relatively large screens (the size of one newspaper page is approximately 400ml), such as newspaper facsimile exposure machines and direct plate-making equipment,
In a light beam scanning optical image recording device that must reproduce high-quality images including Mincho fonts, Gothic fonts, or halftone dot images on a 11×6001 m 1 Il screen, the diameter of the light beam should be adjusted (10 to 100 μm). , increase the scan line density to <
(100 to 2000 lines/1 nch), and as a result of (a), the scanning speed in the sub-scanning direction becomes slower and the scanning time per page becomes longer. Therefore, in order to shorten the recording time, feeding for charging and development is normally performed independently of feeding for sub-scanning.

FIG. 1 shows an example of a device 71 having such a configuration. In this image recording device, a laser beam generated from a laser generator 1 is modulated by a modulator 2. This modulation is performed based on an image signal supplied to the modulator 2. The laser beam has a rotating polygon [3, fθ
A scanning optical system 6 consisting of a lens 4 and mirrors 5a and 5b performs main scanning in the direction of the -side 1 (perpendicular to the plane of the paper in FIG. 1) of the photoreceptor SF on the exposure table 7C. Note that the exposure table 7C is configured to move from the position shown by the solid line to the position shown by the broken line, and sub-scanning is performed by this movement.

The photoreceptor SP is an electrophotographic photoreceptor in which a photoconductive layer is provided on a conductive support.
It passes through a position below the charger 8 while being sent to the charger 8, where it is uniformly charged.

Next, the photoreceptor SP is sent to the exposure table 7C, where it is two-dimensionally scanned by laser light, and an electrostatic latent image is formed on the surface.

Subsequently, the photoreceptor SP is sent to the developing device 9 by the second feeding roller 7b, and the electrostatic latent image is developed with toner and made visible.

In this conventional apparatus, the feeding speed of the photoreceptor SP by the feeding rollers 7a and 7b and the feeding speed by the exposure table 7C are selected to be different values as described above. Therefore, the time from charging to exposure is different between the leading edge and the trailing edge of the screen. As a result, in this type of device, it has not been possible to uniformly reproduce high-quality images on a relatively large screen. That is, - Even if a faithful image can be reproduced at the leading edge of the scanning exposure on the screen, the font will be thinner at the trailing edge, or conversely, even if a good image can be reproduced at the trailing edge, the font will appear in Gothic fonts at the leading edge. There were times when the spelling was crushed.

One possible solution to this problem is to match the charging and developing feed speed to the sub-scanning speed of scanning exposure, but such a configuration introduces the new problem of slowing down the overall processing speed. . It is also possible to shorten the time by operating the charger, imager, and scanning exposure section in G rows with the same speed as described above, but with this configuration, noise can be reduced. Problems with the generation, setting of the feed mechanism, contamination of the optical system, etc. arise.

The present invention has been developed in view of these points, and its purpose is to be able to obtain a uniform, high-quality image over the entire surface, and therefore, to obtain a uniform, high-quality image over the entire surface. An object of the present invention is to provide a light beam scanning type image recording method and apparatus in which characters and drawing lines do not become thicker or thinner at the rear end.

Another object of the present invention is to provide a light beam scanning type image recording method and apparatus capable of rapid image formation.

The method and apparatus of the present invention for achieving this object are characterized in that the intensity of the scanning beam wJ is controlled in accordance with the surface potential of the photoreceptor.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is an explanatory diagram of an embodiment of an apparatus for realizing the method of the present invention. In FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted. In the figure, reference numeral 10 denotes potential detection means such as a surface electrometer, which is used to detect the potential of the scanned portion of the photoreceptor SP immediately before exposure. The detected potential signal is input to the control circuit 11 along with various signals such as an image signal, a signal regarding the scanning position, and a signal specifying the type of photoreceptor, and based on these signals, the signal is sent from the control circuit 11 to the modulator 1. A predetermined signal is output.

FIG. 3 is an explanatory diagram showing a specific configuration of the control circuit 11 and the peripheral portion of A. In this specific example, an acousto-optic modulator is used as the modulator 2 that modulates the laser beam of constant intensity output from the laser generator @1. Also shown in FIG. 2 is a timing detector 32 and a binding side position detector 33, which are not shown in FIG. The timing detector 32 is for detecting the timing of the start of conveyance of the photoreceptor SP (exposure table 7C), and can be configured with a microswitch or an optical <ffi detection stage 1)S+3.

On the other hand, the beam position detector: 'r (() detects the timing when the ceiling light passes the scanning end for each scanning line,
It outputs a pulse that determines the timing of recording.

As is clear from the figure, the control circuit 11 in FIG. 3 includes a first signal control circuit 34, a Batzer memory 35, -
36, a second signal i1+ control circuit 37, a modulator drive circuit 38, a function generator 39, an amplifier 40, and the like. 111(l'i 111I+ control circuit 34 is for alternately reading image signals for one scanning line every 4t from the output of the beam position detector 33 into the buffer memories 35 and 36. The signal control circuit 37 alternately reads out the contents of the buffer memories 35 and 36 based on the output of the beam position detector 33 and outputs them to the modulator drive circuit 38. The high frequency carrier signal is turned on and off according to the output signal (image signal) of the control circuit 37, and the level of the carrier signal is controlled by the output voltage of the function generator 39 or the amplifier 40.

The function generator 39 uses the timing detected by the timing detector 32 as a reference and outputs a signal at a predetermined level that changes according to the light overload time after that, and its output is as follows.
The signal has a level corresponding to the surface potential of the scanned portion of the photoreceptor SP immediately before exposure. Further, the amplifier 40 amplifies the output of the potential detection means 10 as appropriate.

Since both the three function generators and the amplifier 40 change the modulation level of the modulator 2, the modulator drive circuit 3
8, either the output of the amplifier 410 or the output of the function generator 39 may be guided. Therefore, in the actual device configuration, the combination 1! of the potential detection means 10 and the amplifier 40! It is sufficient to provide either one of the combination of the detector 32 and the function generator 39, but in this example C, the output of either -/3 is sent to the modulator drive circuit 3 via the switch 31.
Figure 8 shows a structure configured to selectively lead.

The operation of the image recording apparatus shown in FIGS. 2 and 3 is similar to the operation of the apparatus shown in FIG. The modulation level of changes r:, t (' 94h. Therefore,
In the present invention, the scanning beam intensity changes with the surface potential of the photoreceptor SP, and uniform recording characteristics can be obtained.

This point will be explained in detail using FIGS. 4 and 5.

FIG. 4 shows an example of the image forming process from time f1.-1, where (a> is charging, <b) is scanning exposure, and (
C) shows each development operation, and (d) and (e) show processes for the front end and rear end of the photoreceptor SP, respectively. Further, FIGS. 5(a) and 5(b) respectively show changes in surface potential at the leading end and rear end of the photoreceptor SP (changes due to the darkening table of the photoreceptor). Note that the solid line in FIG. 5 indicates the potential of the unexposed area, and the broken line indicates the potential of the scanning exposed area.

Here, it is assumed that a photoreceptor using a copper phthalocyanine photoconductor is used, t, -2sec, tz=2
．． ! ') sec, t4=7sec, ts (-ts)
=8sec, tv (:ta)=68sec, tg
=69,5sec, tI2=79.5sec
For example, the tip of the sensing body SP is js t, (=-t6-t2)-5,5SeC after charging is completed.
However, the rear end of the photoreceptor SP receives scanning exposure at t7 t4 + t6-14 = 61 seconds after charging is completed (the scanning exposure time is long, but since the scanning beam is focused, the beam The time it takes to hit is short, and as mentioned above
t 5 * t 6. t7==t8). As shown in FIG. 6, this difference in time causes a considerable difference 8 in the surface potentials of the leading and trailing ends during scanning exposure.

For this reason, when scanning exposure is carried out at a constant power of /1 (1 mW/am2 on the surface of the photosensitive material) according to the conventional method, the characters in the image after development become thinner toward the rear end. On the other hand, the output of the scanning beam on the sensitive material surface is 1.1n+ W/cm2° at the leading end and 0.9m W/C at the rear end.
l112 トL/, L h (i'/ 'a tj Li
> If you change it proportionally, it will be on the entire surface! , - The characters are thicker and thinner.Image/i 14+.

Note that the light beam for exposure is not limited to laser light as in the first embodiment, but may also be an incandescent lamp, fluorescent lamp, mercury lamp, or xenon lamp, which is focused by a lens system. KotobC can be done. However, when a high-intensity light beam is required, L[[) or a laser is suitable. In particular, scanning large screens at high speed and high density (there are 6 types)
It is desirable to use laser light as a high-output beam that matches the sensitivity level of the electrophotographic photoreceptor.
r-ion laser-2He-Ne laser, Kr laser, He-Cd laser-4'-, YAGL/- laser, CO2
L/-boo. Among semiconductor lasers, choose one that matches the spectral sensitivity of the photoreceptor. Regarding output: 1mW to 100W
The beam size can be selected from a range of, for example, 20 to 100 la by an optical system.

Furthermore, the light beam intensity can be controlled without using the B-acoustic optical modulator as in the above embodiment. For example, this can be done by controlling the output of the light source itself by changing the input voltage or current of the light source, or by inserting a filter into the optical path or moving the focal plane back and forth to control the effective intensity on the surface of the photoreceptor. In particular, in the case of laser light, a direct modulation method that controls the current in a laser tube or a modulation method that utilizes the electro-optic effect can be used. Taking the above embodiment as an example, if the laser generator 1 is one that can be directly modulated such as a semiconductor laser, the modulator 2 is omitted and the modulator drive circuit 3
8 [It can also be configured to more directly energize the laser generation device 1. Furthermore, the intensity of the scanning exposure beam can be controlled by outputting -Ch<< only for the exposed area, and outputting part of the output for the unexposed area, which is normally in an extinguished state.

In addition, the scanning method is not limited to that of the above-mentioned embodiment.
It is also possible to use a method in which beam deflection is performed using a galvanometer, a conical mirror, or a polygonal pyramid mirror in plane scanning, or a method in which one scans the outer circumference of a cylinder and one scans the inner circumference of the cylinder.

Furthermore, visualization does not necessarily involve only visible image formation <r <
% functional image formation, and can be used, for example, as a toner image as an ink layer in a direct plate-making photosensitive material, or as a resist castle for image-form elution of a photoreceptor.

Further, the detection position by the potential detection means is preferably immediately before the scanning exposure as in the embodiment, but it may be arranged at another position, and if the relationship between the scanning exposure speed of the photoreceptor and the detection position is clear, By determining the dark decay characteristics of the photoconductor in advance, it is possible to predict the potential of the photoconductor during scanning exposure at each f/position.Furthermore, it is possible to predict the surface potential distribution of the photoconductor of the previous plate. The state may be memorized and the intensity of the scanning beam on the photoreceptor of the next plate may be controlled based on this.Of course, if the charging conditions and the dark capital characteristics of the photoreceptor are known, the above implementation can be performed. For example, by using a function generator or the like, it is possible to obtain the L value for optical control without directly detecting the surface potential of the photoreceptor.

As explained above, in the present invention, since the intensity of the light beam is controlled based on the surface potential of the photoreceptor, a uniform, high-quality image can be obtained over the entire surface of the photoreceptor, and the leading edge of the large screen can be It is possible to avoid thickening or thinning of characters, etc. at the rear end.

Further, according to the present invention, image formation can be performed without reducing the conventional image formation speed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a conventional image recording device;
FIG. 2 is a block diagram showing an embodiment of the image recording apparatus according to the present invention, FIG. 3 is a block diagram showing details of the control circuit and peripheral parts, and FIG. 4 is a block diagram showing the timing of the image forming process. Oneto,
FIG. 5 is an explanatory diagram showing changes in the surface potential of the photoreceptor. 1... Laser generator 2... Modulator 3... Rotating polygon mirror 4...
fθ lens 5a, F)b...Mirror 6...Scanning optical system 7a, 7b...Feed roller 7C...Exposure table SP...Photoconductor 8...Charger 9...Developer Device 10...Potential detection means
32...Timing detector 33...Beam position detector 34.37...Signal control circuit 35.36...Buffer 7 memory 38...Modulator drive circuit 39...Function generator 40. ...Amplifier patent applicant Konishiroku Photo Industry Co., Ltd. 1st representative Patent attorney Osamu Ijima Figure 4 Figure 5 (G) Time →

Claims (3)

[Claims] (1) A light beam scanning image recording device characterized in that the intensity of the scanning beam is controlled depending on the surface potential of a photoreceptor charged by a charger. (2) The light beam scanning type image recording according to claim 1, characterized in that the surface potential of the photoreceptor is measured, and the intensity of the scanning beam is controlled based on the measurement result. Method. (3) Charge a charger to the surface of the photoreceptor, scan the light beam to form an electrostatic latent image on the photoreceptor, and develop the electrostatic latent image to create a developed image. In the scanning image recording device obtained, a voltage detection means for detecting the surface potential of the photoreceptor and a control means capable of changing the intensity of the scanning beam are provided,
A light beam scanning type image recording apparatus, characterized in that the control means is configured to change the intensity of the scanning beam in accordance with the output of the potential detection means.