JP2685346B2 - Scanning exposure method using multiple light beams - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a scanning exposure method using a plurality of light beams, and in particular, divides an incident light beam into a plurality of light beams according to the frequency of the incident ultrasonic wave. The present invention relates to a scanning exposure method using a plurality of light beams that generates a plurality of light beams using a multi-frequency acousto-optic element and simultaneously scans and exposes the plurality of light beams.

(Prior art)

Conventionally, there has been proposed a light beam scanning device capable of stable and high-speed reading or recording by forming a plurality of laser beams by using an optical modulator equipped with a multi-frequency acousto-optic device (AOM). 63-5741, JP 54-5455, JP 57-41618,
Japanese Patent Publication No. 53-9856).

In a light beam scanning device such as a laser beam recording device that records an image using such a multi-frequency acousto-optic element,
A plurality of laser beams arranged so that one part overlaps on the photosensitive surface is irradiated to the photosensitive surface, and the laser beam is scanned by a scanning optical system including a rotating polygon mirror (polygon mirror) and a galvanometer mirror. Subscan,
Two-dimensional plane scanning is performed.

That is, the plurality of laser beams are reflected by the reflecting surface of the polygon mirror rotating at a high speed, so that the plurality of main scans are simultaneously performed. After that, the reflected laser beam is reflected by a galvanometer mirror that is rotated at a predetermined speed, so that sub-scanning is performed. By this sub-scanning, the ends of the laser beam group composed of a plurality of laser beams are connected without gaps, whereby an image is formed on a two-dimensional plane.

Recording materials used to record images used in laser beam recording devices and the like are represented by silver salt films represented by silver gelatin films and thermally developed films (dry silver films) and LDFs (laser direct recording films). Non-silver film. In a light beam scanning device such as a laser beam recording device,
A silver salt film such as a dry silver film which is a dry treatment is often used.

[Problems to be solved by the invention]

However, in a light beam scanning device such as a laser beam recording device using a laser beam group, when a silver halide film is used as a recording material, the density characteristic change is affected by reciprocity, reciprocity failure and multiple exposure of the photosensitive material. You. That is, the fact that the end portions of the laser beam group are superimposed on the photosensitive material by sub-scanning, respectively, means that the end portion of the laser beam group for performing the next recording over time on the already exposed portion of the photosensitive material is further increased. This is nothing more than multiple exposure in which exposure is performed repeatedly. It has been conventionally known that in silver salt films, the density due to this multiple exposure increases. The reason why the concentration of the overlapping portion is increased is considered as follows.
In a portion of the photosensitive material exposed to a low power portion (low illuminance) of the laser beam, which is a Gaussian beam, there is a sub-latent image and an initial latent image before the latent image related to the density of the photosensitive material grows. When the laser beam is irradiated again on a portion where the sub-latent image and the initial latent image have grown on the photosensitive material after a predetermined time has elapsed, the already exposed portion becomes pre-exposure and grows into a latent image by re-exposure. This overlapping portion (the connecting portion of a plurality of laser beams) becomes high in density.

Therefore, there is a problem that the density of the overlapping portion on the photosensitive material is increased, thereby causing unevenness in the image density of the obtained film.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a scanning exposure method using a plurality of light beams that minimizes the influence of density unevenness that occurs when exposing a photosensitive material with a plurality of light beams. With the goal.

[Means for solving the problem]

In order to achieve the above object, the present invention is a scanning exposure method using a plurality of light beams, in which m light beams are arranged in a line so that adjacent light beams overlap one another on a photosensitive surface. When performing two-dimensional scanning exposure by performing main scanning for scanning in the direction intersecting with the arrangement direction and sub-scanning for scanning in the arrangement direction of the light beams, the exposure or non-exposure for each of the m light beams is indicated. Using image data, N is an integer of 1 or more, and the exposure of the m-th light beam in the light beam for the Nth main scan and the first light in the light beam for the N + 1th main scan are performed. When the exposure of the beam overlaps with the exposure of the beam, the power of at least one of the first light beam and the m-th light beam is changed and at the same time the first light beam in the light beam for performing the Nth main scanning is changed. m-th light And when one of the first light beams in the light beam for performing the N + 1th main scanning is exposed and the other is not exposed, the power of the light beam corresponding to the exposure is maintained. To do.

In addition, changing the power of the light beam is performed by exposing the m-th light beam in the m-th light beam that performs the N-th main scanning and the m-th light beam in the m-th light beam that performs the (N + 1) th main scanning. When the image density in the portion where the exposure of the first light beam overlaps is high, the power of at least one of the first light beam and the m-th light beam in the m light beams may be lowered. it can.

Note that the m-th light beam in the m light beams for performing the N-th main scanning is used.
When the image density of a portion where the exposure of the first light beam and the exposure of the first light beam in the m light beams for performing the (N + 1) th main scanning overlap each other becomes low, It is also possible to increase the power of at least one of the first light beam and the m-th light beam.

[Action]

According to the present invention, in the scanning exposure method using a plurality of light beams, m light beams are arranged in one row so that one part of the adjacent light beams on the photosensitive surface overlaps, and intersects the arrangement direction of the light beams. Two-dimensional scanning is performed by performing main scanning in the direction of scanning and sub-scanning in the direction of arrangement of the light beams. Therefore, the m-th light beam exposure of the m-th light beam for the N-th main scan and the m + 1th main-scan for the m-th light beam are performed.
The exposure of the first light beam of the book light beam may overlap, and a density change occurs at that portion. Therefore, using the image data representing the exposure or non-exposure of each of the m light beams, the exposure of the m-th light beam in the m light beams performing the N-th main scanning and the (N + 1) th light beam are performed. When the exposure of the first light beam in the m light beams for main scanning overlaps, the m + 1th main scanning is performed.
The powers of at least one of the first light beam in the light beam of the book and the light beam of the m-th light beam in the m light beams for performing the Nth main scan are changed. Along with this, the m-th light beam in the light beam for N-th main scanning and the first light beam in the light beam for N + 1-th main scanning
When one of the light beams of the second one is exposed and the other is not exposed, the power of the light beam corresponding to the exposure is maintained. That is, the power of the first light beam in the m light beams is changed, the power of the m th light beam in the m light beams is changed, or the power of the m th light beam in the m light beams is changed. The powers of both the first light beam and the m-th light beam are changed. On the other hand, when one of the mth light beam of the Nth main scan and the first light beam of the N + 1th main scan is exposed and the other is not exposed, the light beam corresponding to the exposure Maintain power. From the above, it is possible to form an image in which the density change is small in the overlapping portion of the light beams.

Also, changing the power of the light beam is
The exposure of the m-th light beam in the m light beams for the main scanning and the exposure of the first light beam in the m light beams for the (N + 1) th main scanning are performed on the photosensitive material. When the density of the overlapping portion is high, the power of at least one of the first light beam and the m-th light beam is lowered. As a result, the density of the portion where the light beam of the Nth main scan and the light beam of the (N + 1) th main scan overlap on the photosensitive material becomes low, and an image with a small change in density can be formed.

On the other hand, in the m-th light beam that performs the Nth main scanning,
When the image density of the portion where the exposure of the first light beam and the exposure of the first light beam in the m light beams for performing the N + 1th main scanning overlap is low, the first light beam and The power of at least one of the m-th light beam is increased. As a result, the image density of the portion where the light beam of the Nth main scanning and the light beam of the (N + 1) th main scanning overlap on the photosensitive material becomes high, and an image with little density change can be formed.

〔The invention's effect〕

As described above, according to the present invention, when the photosensitive surface is exposed by a plurality of light beams, the image data representing the exposure or non-exposure of each of the m light beams is used.
At least one of the first light beam and the m-th light beam when the exposure of the m-th light beam of the main scanning of the first time and the exposure of the first light beam of the N + 1-th main scanning overlap. Since the power of the light beams is changed, it is possible to provide a scanning exposure method using a plurality of light beams in which the influence of density unevenness occurring in the overlapping portion is reduced as much as possible.
This has the effect.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows a laser beam recording apparatus to which the scanning exposure method using a plurality of light beams according to the present invention is applied. This laser beam recorder has a power supply 14 connected
A He-Ne laser 12 is provided. Instead of this He-Ne laser, another gas laser or semiconductor laser may be used. A lens is provided on the laser beam emission side of the He-Ne laser 12.
16, an AOM (acousto-optic element) 18 and a lens 24 are arranged in order. The AOM 18 includes an acousto-optic medium 21 that produces an acousto-optic effect. On the opposing surface of the acousto-optic medium 21,
A transducer 17 that outputs an ultrasonic wave according to the input high-frequency signal and a sound absorber 19 that absorbs the ultrasonic wave transmitted through the acousto-optic medium 21 are attached. Transducer 17
Are connected to an AOM driver 20 that drives the AOM, and the AOM driver 20 is connected to a control circuit 22. The laser beam output from the AOM 18 is divided into eight laser beams in this embodiment. A mirror 26, a dichroic mirror 25, a polygon mirror (rotary polygonal mirror) 28, a scanning lens 29, and a dichroic mirror 32 are sequentially arranged on the laser beam emitting side of the lens 24. Dichroic mirror
The semiconductor laser 13 is arranged at 25 such that the reference laser beam is incident via the lens 27. A semiconductor laser driver 15 is connected to the semiconductor laser 13.
A polygon driver 30 for rotating the polygon mirror 28 at high speed is connected to the polygon mirror 28. The linear encoder 33 and the photoelectric converter 31 are located at positions where the reference laser beam transmitted through the dichroic mirror 32 can be received.
Are arranged in order. For this reason, the reference laser beam reflected by the polygon mirror 28 is a dichroic mirror.
The light passes through 32 and is scanned on a linear encoder 33. The linear encoder 33 is composed of a flat plate in which a transparent portion and an opaque portion are arranged in a stripe pattern alternately in the main scanning direction at a constant pitch, and the linear laser beam reflected by the polygon mirror 28 is used as a reference laser beam. When scanned by, the reference laser beam passes through the transparent portion, so that a pulse signal is output from the photoelectric converter 31. The pulse signal from the photoelectric converter 31 is input to a carbanometer mirror driver that controls the angle of the galvanometer mirror. On the reflection side of the dichroic mirror 32, the sampling mirror 3
4. The galvanometer mirror 36 and the mirror 38 are arranged in order. A photoelectric converter 60 is arranged at a position where the laser beam transmitted through the sampling mirror 34 can be received. The sampling mirror 34 has a low transmittance that transmits only a laser power sufficient for the photoelectric converter 60. As a result, the reduction in the laser power of the He-Ne laser 12 reflected by the sampling mirror 34 can be reduced. The laser beam reflected by the mirror 38 is applied to a stage 42 through a lens 40. On the stage 42, a recording material 44 such as a microfilm is disposed. The recording material 44 is wound in layers on a reel 46 and a reel 48, respectively.

As shown in FIG. 1, a photoelectric converter is disposed at the above-described position on the laser beam emission side of the AOM 18 and outputs a voltage having a magnitude corresponding to the power of the received laser beam.
Reference numeral 60 is connected to a signal generation circuit 58 that outputs a signal for controlling the amplitude of each signal output from the oscillation circuit (FIG. 4). The local level control signal corresponding to the first image data generated from the signal generation circuit 58 is input to the AOM driver 20 via the modulation circuit 57, and the local level corresponding to the second to eighth image data is input. The control signal is directly input to the AOM driver 20.

The control circuit 22 includes a register 50 for temporarily storing image data and a data converter 52 connected to the register 50. This image data is provided as an 8-bit parallel signal. The data converter 52 outputs a 4-bit parallel signal corresponding to the number of on-states of the 8-bit signal input from the register 50. The data converter 52 is connected with a DAC (digital-analog converter) 54. DAC54
Converts the 4-bit parallel signal output from the data converter 52 into an analog signal and outputs the analog signal to the AOM driver 20. As shown in FIG. 7, the level of the analog signal increases as the number of signal ONs increases. After the image data is delayed for a predetermined time by the delay circuit 56,
The image data corresponding to the first and eighth lines of the eight laser beams as well as being input to the AOM driver 20 are input to the modulation circuit 57.

As shown in FIG. 2, the modulation circuit 57 includes a switch circuit 8 including an analog switch 86A and a gain adjustment circuit 86B.
6, a line memory 80, a synchronizing circuit 82 and an AND circuit 84. The first image data of the eight image data output from the delay circuit 56 is input to one input end of the AND circuit 84, and the eighth image data is input to the input end of the line memory 80. The synchronizing circuit 82 is connected to each of the write control terminal WR and the read control terminal RD of the line memory 80 and receives the video clock (VC, 16.7 MHz). The output end of the line memory 80 is connected to the other input end of the AND circuit 84. The output end of the AND circuit 84 is connected to the control end GT of the analog switch 86A, and the analog switch circuit 86A
A local level control signal corresponding to the first image data of the eight image data is input to the input terminal SI of the signal generation circuit 58. Control terminal C of analog switch 86A
When the low level output of the AND circuit 84 is input to T, the analog switch 86A operates at the input terminal SI and the output terminal S2.
When a high-level output is input to the control end GT by connecting to the analog switch 86A, the analog switch 86A is connected to the input end SI and the output end S.
Connect with 1. One output terminal S1 of the analog switch circuit 86A is connected to the input terminal of the gain adjustment circuit 86B having an amplification gain of less than 1, and the other output terminal S2 is connected to the gain adjustment circuit 86B.
Is input to the AOM driver 20 as a local level control signal corresponding to the first image data generated from the signal generation circuit 58. Second one ~
The local level control signal corresponding to the eighth image data is directly input to the AOM driver 20. Line memory 80
You can use a FIFO (first in first out) or a shift register. Further, the switch circuit 86 may use an arithmetic circuit or an amplifier circuit without using an analog switch.

As shown in FIG. 4, the AOM driver 20 includes oscillation circuits 62A, 62B, 62C, 62D, 62E, 62F, 62F having frequencies f1 to f8, respectively.
G, 62H, local level control circuits 64A, 64B, 64C, 64D,
64E, 64F, 64G, 64H, switch circuit 66A, 66B, 66C, 66
D, 66E, 66F, 66G, 66H. Each of the local level control circuits 64A to 64H is connected to each of the output terminals of the oscillation circuits 62A to 62H, and the output terminals of the local level control circuits 64A to 64H are connected to switch circuits 66A to 66H, respectively.
As the local level control circuit, a double balanced mixer or a pin diode attenuator can be used. Further, each of the level control terminals of the local level control circuits 64A to 64H is provided with a signal generation circuit via a modulation circuit 57.
58 is connected. Then, each of the control terminals of the switch circuits 66A to 66H is connected so that each of the image data output from the delay circuit 56 via the modulation circuit 57 is input.

Each output terminal of the switch circuits 66A and 66B outputs two signals to 1:
Each is connected to the input end of a combiner 68AB that mixes at a ratio of one. Similarly, each output terminal of the switch circuits 66C and 66D is connected to the input terminal of the combiner 68CD, and
Each output terminal of E and 66F is connected to the input terminal of the combiner 68EF, and each output terminal of the switch circuits 66G and 66H is connected to the combiner 68GH.
Is connected to the input terminal of

The output terminal of the combiner 68AB is the total level control circuit 70
It is connected to the amplifier circuit 72AB via AB. Similarly, the output terminal of the combiner 68CD is connected to the amplifier circuit 72CD via the total level control circuit 70CD, and the output terminal of the combiner 68EF is connected to the amplifier circuit 72EF via the total level control circuit 70EF.
The output terminal of the combiner GH is connected to the amplifier circuit 72GH via the total level control circuit 70GH. Each output terminal of the amplifier circuits 72AB and 72CD is connected to the input terminal of the combiner 74, and each output terminal of the amplifier circuits 72EF and 72GH is connected to the combiner 74.
Connected to 76 inputs. The output terminals of the combiners 74 and 76 are connected to the combiner 78, and the output terminals of the combiner 78 are connected to the transducer 17. The total level control circuit is composed of a double balanced mixer and a pin diode attenuator like the local level control circuit, and the output terminal of the DAC 54 of the control circuit 22 is connected to each level control terminal.

Hereinafter, the operation of the present embodiment will be described. The 8-bit image data supplied from the host computer etc.
Is supplied to the delay circuit 56. The data converter 52 outputs a digital signal corresponding to the number of ON signals input from the register 50, and the DAC 54 outputs a seventh signal corresponding to the digital signal.
The analog signal shown in the figure is output. This analog signal is input to each of the control terminals of the total level control circuits 70AB to 70GH. Further, the image data delayed by the delay circuit 56 for a predetermined time at the control end is sent to the AOM through the modulation circuit 57.
It is input to each of the switch circuits 66A to 66H of the driver 20.

When the (N + 1) th main scan is performed, the eighth image data of the image data in the (N + 1) th main scan is stored in the line memory 80 according to the video clock and already stored according to the video clock. The eighth image data of the image data in the Nth main scan is output to the AND circuit 84. The AND circuit 84 compares the first image data of the image data in the N + 1th main scan with the eighth image data of the image data in the Nth main scan. When the eighth image data of the image data in the Nth main scanning and the first image data of the image data in the N + 1th main scanning are both present, the output signal of the AND circuit 84 becomes high level, When at least one of them is absent, the output signal of the AND circuit 84 becomes low level. The switch circuit 86 has N + 1
When the local level control signal corresponding to the first image data of the image data in the first main scan is input and the output of the AND circuit 84 is at high level, the analog switch circuit 86A has the output end on the S1 side, Gain amplification circuit 8
By being input to 6B, the local level control signal corresponding to this first image data becomes small. When the output signal of the AND circuit 84 is low level, the output end of the analog switch circuit 86A is on the S2 side, and the input local level control signal is maintained and output.

After the amplitude is adjusted by the local level control circuits 64A to 64H according to the output signal of the modulation circuit 57, the switch circuits 66A to 66H, the combiners 68AB to 68GH, the total level control circuits 70AB to 70GH, the amplification circuits 72AB to 72GH, the combiner 7
Transducer for AOM18 via 4, 76, combiner 78
Supplied to 17. The transducer 17 converts an input signal into an ultrasonic signal according to the frequency and amplitude of the input signal. This ultrasonic signal propagates through the acousto-optic medium 21 and is absorbed by the sound absorber 19. At this time, He-Ne laser
When the laser beam is oscillated from 12, the laser beam is split by the acousto-optic medium 21 in the power corresponding to the amplitude of the ultrasonic signal and in the direction corresponding to the frequency. AO
The multi-laser beam divided by M18 is scanned in the main scanning direction by the polygon mirror 28, and is scanned in the sub scanning direction by the galvanometer mirror 36.

FIG. 9 shows the angle of the mirror of the galvanometer mirror 36 according to the elapsed time. In the non-recording period before the recording of the n-th exposure is started, the image data of the n-th exposure is prepared, and the recording material is conveyed by one exposure to position the recording material. When the recording is started, the data of the n-th exposure is transferred and the image recording of the n-th exposure is performed until the mirror angle of the galvanometer mirror 36 reaches the recording end angle. During the check period of the non-recording period,
The amplitude adjustment of the signals output from the oscillation circuits 62A to 62H, that is, the level adjustment is performed. At this time, the laser beam emitted from the AOM and transmitted through the sampling mirror 34 is
The light is incident in the direction of the photoelectric converter 60. This level adjustment is performed during the non-recording period before the image recording is started, a constant voltage is applied to the level control terminals of the total level control circuits 70AB to 70GH, and the level is adjusted for each oscillation circuit 62A to 62H. Adjustments are made. In the line memory 80 during the non-recording period,
It is stored as no image data. As a result, the following operation can be performed without modulating the local level control signal in the modulation circuit 57. That is, only the switch circuit 66A is turned on while the signals are output from the oscillation circuits 62A to 62H. The signal output from the oscillation circuit 62A is the local level control circuit 64A, the switch circuit 66A, the combiner 68A.
It is supplied to the transducer 17 via B, the total level control circuit 70AB, the amplification circuit 72AB and the like. This allows AO
The amplitude of the signal output from the oscillation circuit 62A is controlled from the M18 by the local level control circuit 64A, and a laser beam having a power corresponding to the amplitude of the output from the local level control circuit 64A is emitted. The laser beam emitted from the AOM 18 is received by the photoelectric converter 60, and an electric signal corresponding to the power of the laser beam received from the photoelectric converter 60 is output. The signal generation circuit 58 is configured with a set reference value and a photoelectric converter.
The level of the signal input from 60 is compared. When the level of the input signal is higher than the reference value, the signal generating circuit 58 controls the voltage applied to the control end of the local level control circuit 64A so as to reduce the amplitude of the signal,
When the level of the input signal is lower than the reference value, the voltage applied to the control terminal of the local level control circuit 64A is increased to control the amplitude of the signal to increase. As a result, the power of one laser beam emitted from the AOM is adjusted to the target value. Then, the switch circuits 66B to 66H are sequentially turned on, and the oscillation circuits 62B, ...
Level adjustment is performed for 2H, and level adjustment is performed for all of the oscillation circuits 62A to 62H during this check period. During image recording, the signal generation circuit 58 holds the voltage value adjusted as described above.

When data of the n-th exposure is recorded, the register 50, the data converter 52, and the DAC 54 control the total number of ON states of the image data shown in FIG. 7 in each of the total level control circuits 70AB, 70CD, 70EF, and 70GH. The total level control circuit controls the amplitude of the signal output from the combiners 68AB to 68GH in accordance with the analog signal. As a result, the power of each of the laser beams output from the AOM 18 becomes constant irrespective of the number of ON signals, as shown in FIG. 8, thereby preventing image density unevenness due to the number of ON image data. When the amplitude is not controlled by the number of ON signals, the power of one laser beam emitted from the AOM depends on the number of laser beams emitted simultaneously, that is, the number of ON image data in FIG. Changes as shown in FIG.

As will be understood from FIG. 2, the first image data of the eight image data in the N + 1th main scan and the 8th image data in the Nth main scan stored in the line memory 80.
The AND circuit is the eighth image data of the book image data
Since it is input to 84, the output of the AND circuit 84 becomes high level when both image data are recorded.
When at least one of the image data is not recorded, the output of the AND circuit 84 becomes low level. The output of the switch circuit 86 is input to the AOM driver 20 as a local level control signal corresponding to the first image data generated from the signal generation circuit 58. When the output of the AND circuit 84 is low level, the local level control signal corresponding to the eight image data corresponding to the first image data is directly input to the AOM driver 20 by the analog switch 86A.
When the output of the AND circuit 84 is high level, the local level control signal corresponding to the first image data of the eight image data is input to the gain adjusting circuit 86B whose amplification gain is less than 1 by the analog switch 86A. Will be done, so AOM
The local level control signal corresponding to the first image data input to the driver 20 is a local level control signal having a level lower than that of the local level control signal output from the signal generation circuit 58. The local level control signal corresponding to the image data recorded by the first laser beam of the eight laser beams in the N + 1th main scan transmitted from the signal generating circuit 58 is the Nth main scan. Then, the eighth laser beam is modulated according to the presence or absence of recorded image data. Explaining in terms of the power of the laser beam on the photosensitive material, FIG. 5 (1) shows the state of the presence or absence of laser beam recording on the photosensitive surface, showing one part of the overlapping portion in the Nth and N + 1th main scans. There is. N
The recording power on the photosensitive material for the 7th and 8th scans is P1, whereas the recording power for the 8th laser beam in the Nth main scan is as shown in FIG. 5 (2). If there is recording of the eighth image data and recording of the first recording of the N + 1th main scan, the power is lower than P1 in advance.
Set to P2. On the other hand, if there is no recording of the eighth image data and the first recording of the N + 1th main scan is present, the power is maintained at P1.

As a result, regarding the N-th and (N + 1) -th main scans, the eighth of the eight laser beams for performing the N-th main scan
When the exposure of the first laser beam and the exposure of the first laser beam in the eight laser beams for performing the (N + 1) th main scanning overlap, the exposure of the eight laser beams for the (N + 1) th main scanning is performed. The power of the first laser beam is reduced. As described above, in performing the main scanning of eight laser beams at the Nth and N + 1th times, N + 1 main scanning is performed depending on whether the eighth laser beam is exposed or not.
Since the power of the first laser beam in the eight laser beams is reduced by the main scanning of the eighth time, it is possible to form an image with a small density change in the overlapping portion of the laser beams.

In the above, the determination is made depending on the presence or absence of the recording of the eighth image data of the eight laser beams in the Nth main scan, but the eighth laser beam of the eight laser beams in the Nth main scan. The presence / absence of image data recording and the presence / absence of first image data recording of eight laser beams in the N + 1th main scanning are stored, and the first laser beam in the N + 1th main scanning is used for the above determination. Either laser beam or both laser beams may be used. on the other hand,
In the above, the power of the first laser beam of the eight laser beams in the (N + 1) th main scanning is changed, but the recording of the eighth image data of the eight laser beams in the Nth main scanning is performed. The presence / absence and presence / absence of recording of the first image data of the eight laser beams in the N + 1th main scanning may be stored, and the power of the eighth laser beam in the Nth main scanning may be changed. Also, both laser beams may be changed.

As described above, according to the present embodiment, it is possible to reduce reciprocity, reciprocity failure, and density unevenness in a portion where laser beams overlap due to multiple exposure.

Although an example using an acousto-optic element as the optical modulator has been described above, an optical waveguide modulator may be used.

Further, although the example of the light beam scanning device using the laser beam as the light beam has been described above, a scanning device using the light of the LED as the light beam may be used, or another light source may be used as the light beam. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing details of the control circuit of the above embodiment, and FIG. 2 is an example of circuit showing details of the modulation circuit of this embodiment.
FIG. 3 is a schematic diagram showing a laser beam recording apparatus to which the present invention is applied, FIG. 4 is a block diagram showing an AOM driver of an embodiment of the present invention, and FIGS. 5 (1) and (2) are plural laser beams. 6 is a diagram showing the irradiation state on the photosensitive surface and the power of the laser beam, FIG. 6 is a diagram showing the relationship between the number of ONs of the image data and the power of the laser beam, and FIG. Number and the level of the analog signal output from the DAC, FIG. 8 is a diagram showing the relationship between the number of ON of image data and the laser beam power, and FIG. 9 is the angle of the galvanometer mirror. FIG. 5 is a diagram showing a relationship between a check period, a non-recording period, and a recording period. 12 …… He-Ne laser, 18 …… AOM, 57 …… Modulation circuit 64A to 64H …… Local level control circuit,

Claims (3)

(57) [Claims] 1. A main scan and a light beam in which m light beams are arranged in a row so that adjacent portions of the light beam on the photosensitive surface overlap each other and scanning is performed in a direction intersecting with the arrangement direction of the light beams. When performing two-dimensional scanning exposure by performing sub-scanning for scanning in the array direction, N is set to an integer of 1 or more by using image data representing exposure or non-exposure for each of the m light beams, and N
When the exposure of the m-th light beam in the light beam performing the main scanning for the first time and the exposure of the first light beam in the light beam for the N + 1th main scanning overlap with each other, the exposure of the first light beam is performed. The power of at least one of the light beam and the m-th light beam is changed, and the m-th light beam and N + 1 in the light beam for performing the Nth main scan.
A plurality of light beams, characterized in that, when one of the first light beams in the light beam for the main scanning for the first time is exposed and the other is not exposed, the power of the light beams corresponding to the exposure is maintained. Beam scanning exposure method. 2. The power of the light beam is changed when the image density of a portion where the exposure of the first light beam and the exposure of the mth light beam overlap each other is increased. The scanning exposure method using a plurality of light beams according to claim 1, wherein the power of at least one of the first light beam and the m-th light beam is lowered. 3. The power of the light beam is changed when the image quality density of a portion where the exposure of the first light beam and the exposure of the mth light beam overlap each other becomes low. The scanning exposure method with a plurality of light beams according to claim 1, wherein the power of at least one of the first light beam and the m-th light beam is increased.