JPH06125427A - Light beam modulating device - Google Patents

Abstract

PURPOSE:To provide the light beam modulating device which reduces leakage of a light beam from an optical modulator. CONSTITUTION:In an AOM driver 20 which outputs a high frequency signal to drive an AOM 18, mixers 71AB to 71GH are used instead of a switch circuit which is turned on/off in accordance with the picture recordable range. The on/off control circuit which supplies a control signal to mixers 71AB to 71GB controls mixers 71AB to 71GH so that they allow the inputted signal to pass through (turning-on state) or cut off the inputted signal (turning-off state). Thus, the noise outputted at the time of turning-on/off is reduced to about 1/5, and the power of the laser beam emitted from the AOM 18 by this noise at the time of non-recording is so reduced that it can be ignored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam modulator for modulating a light beam.

[0002]

2. Description of the Related Art Conventionally, a light beam scanning device has been proposed which performs stable and high-speed reading or recording by forming a plurality of light beams using an optical modulator equipped with a multi-frequency acousto-optic device (AOM). Has been (Japanese public Sho 63-5
741, JP 54-5455, JP 57-41618, JP 53-9856, JP 55-29414, etc.). In a light beam scanning device such as a light beam recording device that records an image using the AOM, a plurality of high frequency signals having different frequencies are generated in the AOM driver,
The level of the generated high-frequency signal is adjusted and the switch circuit is turned on / off according to the image to be recorded, and the high-frequency signal that has passed through the switch circuit is amplified by the amplifier circuit at a high amplification rate and mixed, and then supplied to the AOM.

As a result, the AOM oscillates in accordance with the supplied high frequency signal, and the light beam incident on the AOM is diffracted in the direction corresponding to the frequency of the high frequency signal with a strength corresponding to the amplitude of the high frequency signal, and the AOM. Emits a plurality of light beams. The plurality of light beams emitted from the AOM are scanned along the main scanning direction by scanning means such as a rotating polygon mirror (polygon mirror), and are also scanned along the sub-scanning direction by scanning means such as a galvanometer mirror. , The recording material is irradiated through the scanning lens. This allows
The irradiation position of the light beam moves two-dimensionally on the recording material, and an image is recorded on the recording material.

By the way, in the AOM driver, a high-frequency component is slightly leaked even when the switch circuit is off, and the high-frequency component is input to the AOM so that the AOM emits a laser beam although the power is very low.
Irradiation outside the image recording range of the recording material may cause some fog. In order to prevent this, the AO
In the M driver, a switch circuit that turns off the output when an image is not recorded is provided separately from the switch circuit in the preceding stage of the amplifier circuit.

The switch circuit is turned on / off in synchronization with the scanning of the laser beam in the main scanning direction. That is, as also shown in FIG. 6, the laser beam recording apparatus records an image in a certain range along the main scanning direction in the scanning range of one main scanning of the laser beam (hereinafter, this range will be referred to as an image recording range). That). The switch circuit is turned on when the position of the laser beam corresponds to the beginning of the image recording range in one main scan, and the position of the laser beam exceeds the image recording range and an image can be recorded (hereinafter referred to as the image recordable range). It is supposed to be turned off when the rear end is reached.
For example, in a laser beam recording apparatus or the like that records an image on a microfilm, the size of the image is determined by the standard of the microfilm. Therefore, as described above, the switch circuit is turned on / off in correspondence with the image recordable range.

[0006]

[Problems to be Solved by the Invention] However, the AOM
When the contacts of the switch circuit are switched in the driver, high frequency noise may occur. When this high frequency noise is amplified by the amplifier circuit at the subsequent stage and input to the AOM, the laser beam slightly leaks, and when the switch circuit is turned on and off as described above, the switch circuit is turned off as shown in FIG. There has been a problem that the leaked laser beam sometimes causes vertical fogging on the recording material. The fogging due to noise when the switch circuit is turned on coincides with the edge portion of the image, so that it is relatively inconspicuous.

In order to prevent this fogging, it may be possible to arrange the switch circuit in the subsequent stage of the amplifier circuit, but it is required that a large power signal current amplified by the amplifier at a high amplification factor can be turned on and off. There is no switch circuit that satisfies the performance (isolation, 2 signal characteristics, cost, etc.).

The present invention has been made in consideration of the above facts, and an object thereof is to obtain a light beam modulator capable of reducing the leakage of a light beam from an optical modulator.

[0009]

In order to achieve the above object, a light beam modulator according to the present invention controls an oscillation circuit for outputting a signal of a predetermined frequency and an amplitude of the signal output from the oscillation circuit. A series circuit in which a level control circuit and a switch circuit that is turned on / off according to image data are connected in series, an on / off means that is connected to the series circuit and is turned on / off according to an input control signal, and output from the on / off means And an optical modulator for diffracting and emitting a light beam incident with a power corresponding to the amplitude of the signal output from the amplifier circuit and in a direction according to the frequency. In the light beam modulator, the on / off means is composed of a mixer.

A plurality of oscillation circuits, series circuits, ON / OFF means, and amplifier circuits are provided, and a plurality of signals are mixed by at least one combiner and input to the optical modulator, whereby optical modulation is performed. A plurality of light beams may be diffracted and emitted from the container.

Further, the light beam modulator is applied to a light beam recording device for recording an image on a recording material by scanning the light beam emitted from the light modulator along a predetermined direction, and the on / off means is And is turned on so that the head of the image recordable range coincides with the head of the image recording range for a time corresponding to a predetermined image recordable range along the scanning direction of the light beam. be able to.

The light beam modulator is applied to a light beam recording device for scanning an optical beam emitted from the light modulator along a predetermined direction to record an image on a recording material, and the on / off means is , Is turned on so that the center of the image recordable range coincides with the center of the image recordable range for a time corresponding to a predetermined image recordable range along the scanning direction of the light beam. be able to.

[0013]

According to the present invention, the input control is connected to the series circuit having the level control circuit for controlling the amplitude of the signal of the predetermined frequency output from the oscillation circuit and the switch circuit which is turned on / off according to the image data. The mixer constitutes on / off means that is turned on / off according to a signal.
The mixer is generally capable of mixing a plurality of signals and changing the mixing ratio. Therefore, when the on / off means is constituted by the mixer, it is sufficient to input a control signal to the mixer so that the mixing ratio becomes 0% (off) or 100% (on). The inventor of the present application has confirmed that the noise level generated when the mixer is turned on and off is reduced to about ⅕ by using the mixer. As a result, the level of the signal component input to the optical modulator at the time of turning on and off is reduced, so that the leakage of the light beam from the optical modulator can be reduced. Also, the cost of the mixer is lower than that of the conventional switch circuit, and the mixer can be realized more easily.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a laser beam recording apparatus 10 according to the present invention. The laser beam recording device 10 is H
An e-Ne laser 12 is provided. He-Ne laser 1
2 is connected to a power source 14 and emits a red laser beam of visible light. A lens 16, an AOM (acousto-optical element) 18 as an optical modulator, and a lens 24 are sequentially arranged on the laser beam emitting side of the He-Ne laser 12.

The AOM 18 has an acousto-optic medium 21 that produces an acousto-optic effect. A transducer 17 that outputs an ultrasonic wave according to an input high frequency signal and a sound absorber 19 that absorbs the ultrasonic wave that has passed through the acousto-optic medium 21 are attached to the opposing surfaces of the acousto-optic medium 21. The transducer 17 is connected to the AOM driver 20 that drives the AOM 18, and the AOM driver 20 is connected to the control circuit 22. In this embodiment, AOM1
A maximum of eight laser beams are diffracted from the laser beam incident on the laser beam No. 8 and emitted as a recording laser beam.

A mirror 26, a dichroic mirror 25, a polygon mirror (rotary polygon mirror) 28, a lens 29 and a dichroic mirror 32 are arranged in this order on the laser beam emitting side of the lens 24. A lens 27 and a semiconductor laser 13 are arranged near the dichroic mirror 25. The semiconductor laser 13 is connected to the semiconductor laser driver 15 and driven by the semiconductor laser driver 15. The semiconductor laser 13 emits, as a synchronizing laser beam, a laser beam having a wavelength greatly different from the wavelength of the recording laser beam.

The synchronizing laser beam emitted from the semiconductor laser 13 is incident on the dichroic mirror 25 via the lens 27. The dichroic mirror 25 is configured to reflect light having a wavelength corresponding to the synchronizing laser beam emitted from the semiconductor laser 13 and transmit light having other wavelengths. Therefore, the recording laser beam incident on the dichroic mirror 25 is transmitted through the dichroic mirror 25, and the synchronizing laser beam is reflected by the dichroic mirror 25, and each is combined and emitted in the same direction, that is, toward the polygon mirror 28 side. .

The polygon mirror 28 is connected to a polygon mirror driver 30, and the polygon mirror driver 3
The laser beam is rotated at a high speed by 0 and the incident laser beam is scanned in the main scanning direction. The polygon mirror driver 30 includes a rotation speed detection unit (not shown) that detects the rotation speed of the polygon mirror 28, and controls the polygon mirror 28 to rotate at a constant speed.

The recording laser beam and the synchronizing laser beam reflected by the polygon mirror 28 and scanned in the main scanning direction are incident on the dichroic mirror 32 via the lens 29. The dichroic mirror 32 is configured to reflect light having a wavelength corresponding to the recording laser beam and transmit light having other wavelengths. Therefore, the recording laser beam incident on the dichroic mirror 32 is reflected, and the synchronizing laser beam is transmitted through the dichroic mirror 32 and demultiplexed. A linear encoder 33 and a photoelectric converter 31 are sequentially arranged on the synchronizing laser beam emission side of the dichroic mirror 32. As a result, the synchronizing laser beam transmitted through the dichroic mirror 32 scans the linear encoder 33.

The linear encoder 33 is composed of a flat plate in which a plurality of transparent portions and opaque portions are alternately arranged at a constant pitch in a striped pattern along the main scanning direction. When this linear encoder 33 is scanned with the synchronizing laser beam reflected by the polygon mirror 28, the synchronizing laser beam transmitted through the transparent portion is photoelectrically converted by the photoelectric converter 31, and a signal generation circuit connected to the photoelectric converter 31. A pulse signal is output to 100. This pulse signal represents scanning in the main scanning direction,
Specifically, the number of pulses corresponds to the position on the main scanning line of the laser beam of the synchronizing laser beam, and the interval between each pulse corresponds to the main scanning speed of the synchronizing laser beam.

In the signal generating circuit 100, a galvanometer mirror control signal for synchronizing the scanning in the sub scanning direction by the galvanometer mirror 36, which will be described later, with the scanning in the main scanning direction based on the input pulse signal, and AOM1.
And a video clock signal for synchronizing the laser beam modulation in 8 with the scanning in the main scanning direction. The galvanometer mirror control signal controls the angle of the galvanometer mirror. Galvanometer mirror driver 3
6A, the video clock signal is input to the character generation circuit 9
4 and on / off control circuit 98 (see FIG. 2).

On the reflection side of the dichroic mirror 32,
A mirror 34, a galvanometer mirror 36, and a mirror 38 are arranged in order. The galvanometer mirror 36 is connected to the galvanometer mirror driver 36A. The galvanometer mirror driver 36A controls the operation of the galvanometer mirror 36 based on the aforementioned galvanometer mirror control signal so that the galvanometer mirror 36 performs scanning in the sub scanning direction in synchronization with scanning in the main scanning direction. The recording laser beam scanned in the sub scanning direction by the galvanometer mirror 36 and reflected by the mirror 38 is
The stage 42 is illuminated through the lens 40.

A laser beam is provided between the mirror 38 and the lens 40 at the time of non-recording (for example, when recording is changed from one frame to another frame or when recording is changed from one fish to another fish). A shutter 61 is arranged so as to close the shutter. This shutter 6
A photoelectric converter 60 is attached to the surface of No. 1 on the laser beam incident side. A recording material 44 such as a microfilm is arranged on the stage 42. The recording material 44 is composed of a silver salt film such as a micro film which is sensitive to light having a wavelength in the visible light range. The recording material 44 is wound around the reel 46 and the reel 48 in layers.

As shown in FIG. 2, the photoelectric converter 60 is connected to the input terminal of the amplifier 88 of the control circuit 22. An ADC (analog-digital converter) 82 and a register 90 are sequentially connected to the output terminal of the amplifier 88. ADC
Reference numeral 82 converts the signal output from the photoelectric converter 60 and amplified by the amplifier 88 into digital data representing the power of the received laser beam. The register 90 temporarily holds the digital data. The register 90 is connected to the data bus line 92. Data bus line 92
A CPU (Central Processing Unit) 80 is also connected to the CPU, and data and commands can be input and output between them. The CPU 80 performs processing based on the data representing the power of the laser beam held in the register 90.

The data bus line 92 has a register 84.
A, 84B, 84C, 84D, 84E, 84F, 84
G and 84H are connected, and each register is DAC
(Digital-analog converter) 86A, 86B, 86
It is connected to C, 86D, 86E, 86F, 86G and 86H. Digital data for adjusting the level of each of the eight laser beams emitted from the AOM 18 is supplied to the registers 84A to 84H. This digital data is converted into an analog signal by each DAC 86, and the local level control circuits 64A to 64A of the AOM driver 20 which will be described later.
It is output as a level control signal to each of 4H.

The data bus line 92 has a character generating circuit 9
4 is connected. Image data transferred from the host computer or the like is supplied to the character generation circuit 94, and the character generation circuit 94 temporarily stores the image data. Character generation circuit 94
A delay circuit 58 and a signal number counting circuit 54 are connected to the input terminal, and the aforementioned video clock signal is input. The character generation circuit 94 uses the image data (8
Bit) and outputs it to the delay circuit 58 and the signal number counting circuit 54 in synchronization with the video clock signal, that is, the scanning of the laser beam in the main scanning direction.

The delay circuit 56 delays the input image data for a predetermined time and then outputs it to each of switch circuits 66A to 66H of the AOM driver 20 which will be described later. Therefore, the switch circuits 66A to 66H are turned on / off in synchronization with the scanning of the laser beam in the main scanning direction. On the other hand, the signal number counting circuit 54 converts the input 8-bit image data into 4-bit data representing the number of ON (1) of 8 bits,
Output to the second DAC (digital-analog converter) 56.

A register 50 and a first DAC (digital-analog converter) 52 are sequentially connected to the data bus line 92. 8-bit correction data is supplied to the register 50 from the CPU 80. This correction data is a correction amount for making the power per laser beam emitted from the AOM 18 constant regardless of the number of laser beams emitted even when the amplitude of the signal input to the AOM 18 is changed. Is represented.

The register 50 temporarily holds the supplied correction data and outputs it to the first DAC 52. First DAC
At 52, the input digital correction data is converted into an analog signal having a voltage level corresponding to the correction amount. The output terminal of the first DAC 52 is connected to the reference voltage input terminal of the second DAC 56, and the first DAC 52 outputs the analog signal of the voltage level corresponding to the correction amount to the reference voltage V _REF.
Is supplied to the second DAC 56.

As shown in FIG. 4, the voltage level of the signal output from the second DAC 56 depends on the signal number counting circuit 54.
Becomes larger as the value of the data input from, i.e., as the number of ONs of the image data becomes larger, the degree of increase changes according to the voltage level of the reference voltage V _REF . That is, when the voltage level of the reference voltage V _REF is large, the degree to which the output voltage level of the second DAC 56 becomes high with respect to the increase in the number of ON of the image data becomes large (the inclination becomes large).

Further, when the voltage level of the reference voltage V _REF is small, the second number is added to the increase in the number of image data turned on.
The degree to which the output voltage level of the DAC 56 increases becomes small (the inclination becomes small). The magnitude of this slope depends on the reference voltage V
It changes continuously according to the voltage level of _REF . Therefore,
The slope can be changed by changing the voltage level of the reference voltage V _REF , that is, the value of the correction data supplied to the register 50. It should be noted that the voltage level of the signal output from the second DAC 56 when the number of turned-on image data is 1 is set so as not to change even if the reference voltage V _REF is changed. The output signal from the second DAC 56 is amplified by the amplifier 96 and then supplied as an amplitude correction signal to each of total level control circuits 70AB to 70GH of the AOM driver 20 described later.

An ON / OFF control circuit 98 as a control signal generating means is connected to the data bus line 92. Data representing an image recordable range is input from the CPU 80 to the on / off control circuit 98. A video clock signal is input to the on / off control circuit 98 from the signal generation circuit 100, and the AOM is generated only when the position of the laser beam in the main scanning direction corresponds to the image recordable range.
The driver 20 outputs an on / off control signal for outputting a signal. The on / off control signal is supplied to the mixers 71AB to 71GH of the AOM driver 20.

As shown in FIG. 3, the AOM driver 20 has oscillating circuits 62A, 62B, 6 having frequencies f1 to f8, respectively.
2C, 62D, 62E, 62F, 62G, 62H, local level control circuits 64A, 64B, 64C, 64D,
64E, 64F, 64G, 64H, switch circuit 66
A, 66B, 66C, 66D, 66E, 66F, 66
Equipped with G and 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 switch terminals 66A to 66H are respectively connected to the output terminals of the local level control circuits 64A to 64H. .
A double balanced mixer or a pin diode attenuator can be used as the local level control circuit. The level control signals from the aforementioned DACs 86A to 86H are input to the respective level control terminals of the local level control circuits 64A to 64H. The delay circuit 58 is provided at each of the control terminals of the switch circuits 66A to 66H.
1-bit of each of the image data input by the 8-bit parallel signal is input.

Each output terminal of the switch circuits 66A and 66B has a combiner 6 for mixing two signals at a ratio of 1: 1.
Each of them is connected to the input terminal of 8AB. Similarly, the output terminals of the switch circuits 66C and 66D have a combiner 68CD.
Of the switch circuits 66E and 66F are connected to the input ends of the combiners 68EF, and the output ends of the switch circuits 66G and 66H are connected to the combiner 68G.
It is connected to the input terminal of H.

The output terminal of the combiner 68AB is connected to the total level control circuit 70AB. Similarly, the output terminal of the combiner 68CD is connected to the total level control circuit 70.
The output terminal of the combiner 68EF is connected to the CD and is connected to the total level control circuit 70EF.
The output terminal of GH is connected to the total level control circuit 70GH. Total level control circuit 70AB to 70G
The amplitude correction signal output from the amplifier circuit 96 of the control circuit 22 is distributed and supplied to each level control terminal of H.

In addition, the total level control circuit 70AB-
70GH is a mixer 71AB, 71CD, 71EF,
It is connected to each 71GH. Mixer 71AB-7
The ON / OFF control circuit 9 of the control circuit 22 is provided at the control end of 1 GH.
The on / off control signal input from 8 is supplied. This on / off control signal is a 100% input signal to the mixer.
% Pass (hereinafter, this state is called "on"),
Alternatively, it is a signal that switches the mixer so that it is cut off 100% (hereinafter, this state is referred to as "off"). The output end of the mixer 71AB is connected to the combiner 74 via the amplifier circuit 72AB. Similarly, the output end of the mixer 71CD is connected to the combiner 74 via the amplifier circuit 72CD, and the output end of the mixer 71EF is the amplifier circuit 72EF.
Connected to the combiner 76 via the mixer 71GH
The output end of is connected to the combiner 76 via the amplifier circuit 72GH.

The output terminals of the combiners 74 and 76 are connected to the combiner 78, and the output terminal of the combiner 78 is connected to the input terminal of the amplifier circuit 79. The amplifier circuit 79 amplifies the input signal with a constant amplification factor. Amplifier circuit 7
The output of 9 is connected to the transducer 17 of the AOM 18.

Next, the operation of this embodiment will be described. He-N
The laser beam emitted from the e-laser 12 is the AOM 18
Is incident on. On the other hand, the signals output from the oscillation circuits 62A to 62H are the local level control circuits 64A to 64H.
Is output to. Local level control circuits 64A to 64H
A level control signal is input to each of the DACs 86A to 86H, and the amplitude is adjusted based on the level control signal. The signals whose amplitudes have been adjusted by the local level control circuits 64A to 64H are switch circuits 66A to 66H, combiners 68AB to 68GH, and a total level control circuit 70A.
It is input to the mixers 71AB to 71GH via the B to 70GH.

At this time, the mixers 71AB to 71AB are controlled by the ON / OFF control signal supplied from the ON / OFF control circuit 98.
When 1GH is turned on, the input signal passes through the mixers 71AB to 71GH, and the amplifier circuit 72
AB to 72GH, combiners 74 and 76, combiner 7
After being mixed via 8, amplified at a constant amplification rate by the amplifier circuit 79, and supplied to the transducer 17 of the AOM 18.

The transducer 17 converts the input signal into an ultrasonic signal according to the number, frequency and amplitude of the input signal. This ultrasonic signal is transmitted to the acousto-optic medium 2
1 is propagated and is absorbed by the sound absorber 19. This makes H
The same number of laser beams as the number of signals input from the laser beam incident from the e-Ne laser 12 are emitted as recording laser beams in a direction corresponding to the power of the signal amplitude and the frequency of each signal. It

The recording laser beam emitted from the AOM 18 is incident on the dichroic mirror 25 via the lens 24 and the mirror 26, and is transmitted through the dichroic mirror 25. The synchronizing laser beam emitted from the semiconductor laser 13 is also incident on the dichroic mirror 25 via the lens 27, reflected by the dichroic mirror 25, and combined with the recording laser beam. The combined laser beam is emitted to the polygon mirror 28 side, reflected by the polygon mirror 28, and scanned in the main scanning direction.

The laser beam scanned in the main scanning direction is incident on the dichroic mirror 32 through the lens 29, the recording laser beam is reflected by the dichroic mirror 32, and the synchronizing laser beam passes through the dichroic mirror 32. It is split. The synchronization laser beam transmitted through the dichroic mirror 32 scans the linear encoder 33. The laser beam for synchronization transmitted through the transparent portion of the linear encoder 33 is converted into the photoelectric converter 31.
Is photoelectrically converted by, and a pulse signal corresponding to the scanning in the main scanning direction is output.

The signal generating circuit 100 generates a galvanometer mirror control signal and a video clock signal on the basis of the pulse signal, supplies the galvanometer mirror control signal to the galvanometer mirror driver 36A, and supplies the video clock signal to the character generating circuit 94, It is supplied to the on / off control circuit 98.

As shown in FIG. 5A, when an image A having a predetermined size (here, the size according to the standard of the microfilm) is recorded on the recording material 44, the CPU 80
Sets in advance the information indicating the image recordable range along the main scanning direction in the on / off control circuit 98. The image recordable range is changed by the user operating the ten keys or the like, or by changing the recording mode such as the image size to be recorded by an instruction from the host computer. The on / off control circuit 98 determines the position of the laser beam along the main scanning direction based on the input video clock signal, and changes the control signal when the position corresponds to the head of the set image recording range. Then, the mixers 71AB to 71GH are turned on. As a result, the mixers 71AB to 71GH are switched so that the input high frequency signal passes through 100%.

On the other hand, the character generation circuit 94 converts the image data supplied from the host computer or the like into image data of every 8 bits, and the position in the main scanning direction of the laser beam represented by the input video clock signal is at the head of the image recording range. From the time of correspondence, the image data is output to the delay circuit 58 and the signal number counting circuit 54 in the order of recording the image by the laser beam. The 8-bit image data delayed by the delay circuit 58 for a predetermined time is distributed to each of the switch circuits 66A to 66H by 1 bit and input. Switch circuits 66A to 66
H passes a signal when the input 1-bit image data is on (1), and cuts off the signal when it is off (0).

Further, the signal number counting circuit 54 outputs a digital signal corresponding to the number of ON signals input from the character generating circuit 94 to the second DAC 56. The correction data converted into the analog signal via the register 50 and the first DAC 52 is input to the second DAC 56 as the reference voltage V _REF together with the digital signal corresponding to the number of ONs of the signal, and the laser beam emitted from the AOM 18 is output. An amplitude correction signal is output to make the power per single laser beam constant regardless of the number of laser beams to be emitted. This amplitude correction signal is applied to the total level control circuit 70A.
It is input to each of the control terminals of B to 70 GH.

Total level control circuits 70AB to 70G
H adjusts the amplitude of the signal that has passed through the switch circuits 66A to 66H based on the input amplitude correction signal. The signals whose amplitudes have been adjusted by the total level control circuits 70AB to 70GH pass through the mixers 71AB to 71GH, and are amplified by the amplifier circuits 72AB to 72GH and the combiners 74 and 7.
6. AOM 18 via the combiner 78 and the amplifier circuit 79
Is supplied to the transducer 17. The AOM 18 modulates the laser beam according to the input signal and emits a recording laser beam according to the image to be recorded. As described above, the recording laser beam is scanned in the main scanning direction by the polygon mirror 28, reflected by the dichroic mirror 32, and then irradiated on the recording material 44 via the galvanometer mirror 36 and the lens 40.

When the position of the laser beam along the main scanning direction reaches the rear end of the image recording range, the recording of the image in one main scanning is completed. At this time, the mixer 71AB
The ~ 71GH is still in an ON state that allows high-frequency signals to pass through. When the position of the laser beam further moves and the position of the laser beam reaches the rear end of the image recording range, the on / off control circuit changes the control signal, and the mixer 71AB
Turn off ~ 71GH. As a result, the mixer 71A
B to 71GH are switched so as to block 100% of the input high frequency signal.

Since the mixers 71AB to 71GH are used in the present invention in place of the conventional switch circuit, the noise generated when the mixer is switched off is very small.
Since the power of the laser beam leaking from the OM 18 is also negligibly small, the fog as shown in FIG. 6A does not occur in the non-image portion. Also, the mixer 71A
While B to 71GH is off, the high frequency component does not leak to the amplifier circuits 72AB to 72GH as in the conventional case.

While the above processing is repeated,
The recording material 4 is recorded by rotating the mirror of the galvanometer mirror 36 in response to the aforementioned galvanometer mirror control signal and scanning the recording laser beam in the sub-scanning direction.
Image A is recorded without fogging or the like on 4.

Further, the laser beam recording apparatus 1 of this embodiment
In 0, it is possible to record an image (for example, image B or image C shown in FIG. 5A) having a size different from the size (image A) corresponding to the microfilm standard.
In this case, the head of the image recordable range is used as a reference, and the image is recorded so that the head of the image recordable range matches the head of the image recordable range.

In the above-described embodiment, the image is recorded with the start of the image recording coincident with the beginning of the image recordable range, but the present invention is not limited to this. Conventionally, by recording an image as described above, the fogging that occurs when the switch is turned on in the switch circuit of the AOM driver 20 is caused to be inconspicuous at the edge portion of the image, but by applying the present invention, Since the fog does not occur, for example, as shown in FIGS. 5C and 5D, the image is recorded so that the center of the image recording range along the main scanning direction coincides with the center of the image recordable range. May be. In this case, images B and C having different sizes are shown in FIG.
It can be recorded as shown in (C).

In the above embodiment, the example in which the sub-scanning is performed by the galvanometer mirror 36 has been described, but the recording material 44 is conveyed in synchronization with the scanning in the main scanning direction based on the pulse signal output from the photoelectric converter 31. Alternatively, the recording material 44 may be irradiated with a laser beam scanned only in the main scanning direction to record an image on the recording material 44.

Further, in the above, the AOM is used as the optical modulator.
Although the example using the (acousto-optic element) 18 has been described,
An optical waveguide modulator may be used. Further, a recording material 44 other than the silver salt film, for example, a heat mode recording material such as a laser direct recording film (LDF) may be used.

Although the laser beam recording device 10 has been described as an example of the light beam recording device in the above, it can be applied to various light beam recording devices that use light from an LED or another light source as a beam. Further, the light beam modulation device according to the present invention can be applied to a device that performs reading using a light beam.

[0057]

As described above, according to the present invention, a series circuit including a level control circuit for controlling the amplitude of a signal of a predetermined frequency output from an oscillation circuit and a switch circuit which is turned on / off according to image data is provided. Since the ON / OFF means that is connected and input and is turned on / off according to the input control signal is constituted by the mixer, it is possible to obtain an excellent effect that the leakage of the light beam from the optical modulator can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a laser beam recording apparatus according to an embodiment.

FIG. 2 is a block diagram showing a schematic configuration around a control circuit of a laser beam recording apparatus.

FIG. 3 is a block diagram showing a schematic configuration of an AOM driver.

FIG. 4 is a diagram showing a change in the relationship between the number of signal ONs and the level of an output signal when the reference voltage V _REF of a DAC (digital-analog converter) is changed.

5A and 5B are plan views and timing charts of a recording material for explaining on / off of a mixer and timing of image recording in the present embodiment, and FIGS. 5C and 5D are on / off of a mixer and FIG. 7A and 7B are a plan view and a timing chart of a recording material showing another example of image recording timing.

FIG. 6A is a plan view of a recording material showing a fog of the recording material due to switching of contacts of the switch circuit, and FIG. 6B is a timing chart showing ON / OFF timing of the switch circuit.

[Explanation of symbols]

 10 Laser Beam Recording Device 18 AOM 20 AOM Driver 62 Oscillation Circuit 64 Local Level Control Circuit 66 Switch Circuit 70 Total Level Control Circuit 71 Mixer 72 Amplification Circuit 98 On / Off Control Circuit

Claims (4)

[Claims] 1. A serial circuit in which an oscillation circuit that outputs a signal of a predetermined frequency, a level control circuit that controls the amplitude of the signal output from the oscillation circuit, and a switch circuit that is turned on / off according to image data are connected in series. A circuit, an on / off means connected to the series circuit and turned on / off according to an input control signal, an amplifier circuit for amplifying a signal output from the on / off means, and an amplitude of a signal output from the amplifier circuit. In a light beam modulator having a light modulator for diffracting and emitting a light beam incident with a power according to a frequency and according to a frequency, a light beam characterized in that the on / off means is constituted by a mixer. Modulator. 2. The oscillator circuit, the series circuit, the on / off means, and the amplifier circuit are respectively provided in plural, and at least one is provided.
2. The light beam according to claim 1, wherein a plurality of signals are mixed by one combiner and input to the optical modulator, whereby a plurality of light beams are diffracted and emitted from the optical modulator. Modulator. 3. The light beam modulator is applied to a light beam recording device for recording an image on a recording material by scanning a light beam emitted from the light modulator along a predetermined direction,
The on / off means is turned on so that the head of the image recordable range and the head of the image recording range coincide with each other for a time corresponding to a predetermined image recordable range along the scanning direction of the light beam. The light beam modulator according to claim 1 or 2, characterized in that: 4. The light beam modulator is applied to a light beam recording device for recording an image on a recording material by scanning a light beam emitted from the light modulator along a predetermined direction,
The on / off means is turned on so that the center of the image recordable range coincides with the center of the image recordable range for a time corresponding to a predetermined image recordable range along the scanning direction of the light beam. The light beam modulator according to claim 1 or 2, characterized in that: