JPH10157199A - Image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute image recording without using an AOM or the like and to enhance an exposing intensity when a laser light is emitted on a thermally sensitive material. SOLUTION: A signal LD 36 is driven by a signal LD driver 38 by using a trigger signal on which image data is superimposed and emits a laser signal light having pulse oscillation which is modulated by means of the image data. Each of a preamplifier 42 and a power amplifier 46 comprises an optical fiber which is so constituted that an element such as erbium is doped into a part of a quartz fiber. The optical fiber is excited by allowing a laser exciting light emitted from an exciting LD to be incident on the optical fiber. When the laser signal light from the signal LD 36 is incident on the optical fiber, the raised energy condition is released and the laser signal light is amplified. A clock generator 30 generates a trigger signal having a constant cycle based on a control signal from a control circuit 32. A superimposing circuit 28 superimposes image data on the trigger signal and outputs it to the signal LD driver 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating a laser signal beam to perform thermal ablation.
The present invention relates to an image recording apparatus for recording an image on a heat-sensitive recording medium by a thermal reaction such as n), melting or sublimation.

[0002]

2. Description of the Related Art In the technical field of image recording, in recent years,
Process-less processes such as elimination of the development process are progressing. Therefore, instead of silver halide photographic materials requiring the development process, thermal photographic materials which do not require the development process have been used as image recording media. Was. However, many of the thermal photosensitive materials have extremely low sensitivity (that is, the minimum energy density required for causing a reaction to be extremely large) as compared with the silver salt photosensitive material, and therefore, the laser signal light is applied to the thermal photosensitive material. When performing image recording by using a laser, it is necessary to prepare a high-output laser.

[0003] Conventionally, as a high-output laser, YAG
And solid-state lasers using YVO4 are known,
All of them have problems such as being large and expensive, and low in energy efficiency.

Therefore, conventionally, for example, Japanese Patent Laid-Open Publication No.
As described in Japanese Patent No. 01159, an image recording apparatus using a so-called fiber laser instead of a solid-state laser has been proposed.

[0005]

However, the fiber laser used in this proposed example has a continuous wave (C
In order to emit a continuous wave (W) laser beam, in order to record an image with the laser beam, the emitted laser beam is converted into an acousto-optic modulator (AOM).
It is necessary to modulate with image data using an optic modulator or the like.

In general, an AOM includes an acoustic medium for transmitting ultrasonic waves and an ultrasonic vibrator for exciting the ultrasonic waves in the medium. The refractive index of the acoustic medium changes when it is not transmitted. Therefore, when laser light is passed through the acoustic medium so as to be orthogonal to the transmission path of the ultrasonic wave, for example, when the ultrasonic wave is transmitted, the laser light is diffracted when crossing the transmission path of the ultrasonic wave, Does not diffract when not transmitted.
Therefore, while driving the ultrasonic transducer based on the image data, the laser light emitted from the fiber laser is incident on the acoustic medium, and only the diffracted laser light is irradiated on the image recording medium. Can be applied to the image recording medium intermittently according to the image data.

However, when performing modulation using such an AOM, there are the following problems. That is, the rise time and the fall time of the laser light intermittently applied to the image recording medium are determined by the ultrasonic waves (carrier waves) in the AOM.
, The rise time and the fall time cannot be shortened to a certain time (for example, 10 ns) or less. For this reason, the image recording speed cannot be increased beyond a certain speed (40 to 50 Mbps).
There is a problem that lines in the main scanning direction are dull.

Further, the optical system using the AOM requires complicated and delicate adjustment, so that productivity and workability are not very good.

Generally, laser light emitted from a fiber laser is infrared light. On the other hand, in AOM,
The energy required as carrier (ultrasonic) energy increases in proportion to the square of the wavelength of the laser light. Therefore, AOMs used for laser light emitted from fiber lasers (ie, AOMs for infrared light) are generally expensive because they require more carrier energy.

Further, as described above, since a continuous oscillation laser beam is used as the laser beam for irradiating the thermal photosensitive material, there are the following problems. That is, the thermal sensitive material generally has the property that the higher the exposure intensity (peak intensity), the higher the sensitivity (that is, the lower the energy density required for causing a reaction to occur). More efficient image recording can be performed by using a laser beam that increases the exposure intensity as the laser beam to be applied to the photosensitive material. However, when a continuous oscillation laser beam is used as the laser beam for irradiating the thermal photosensitive material, the exposure intensity cannot be increased beyond a value determined by the output and the beam diameter, so that efficient image recording is performed. Can not do.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, to perform image recording without using an AOM or the like, and to provide an exposure intensity when a thermal light-sensitive material is irradiated with a laser beam. To provide an image recording apparatus capable of increasing the image quality.

[0012]

In order to achieve at least a part of the above object, the present invention irradiates a thermosensitive recording medium with a laser signal beam modulated by image data. An image recording apparatus that records an image represented by the image data on the heat-sensitive recording medium, wherein the laser signal light emitting unit emits a laser signal light modulated by the image data, and a predetermined element is doped. A laser signal light amplifying means for amplifying the intensity of the laser signal light through the emitted laser signal light to the optical fiber after exciting the optical fiber with laser excitation light, Transmitting means for transmitting the amplified laser signal light to irradiate the heat-sensitive recording medium.

As described above, in the present invention, the laser signal light emitting unit emits the laser signal light modulated by the image data. The laser signal light amplifying unit passes the emitted laser signal light through an optical fiber to amplify the intensity of the laser signal light. The optical fiber is doped with a predetermined element, and is further excited by laser excitation light. Here, to excite the optical fiber specifically means to raise the energy state of atoms and the like in the optical fiber. The transmission means transmits the amplified laser signal light and irradiates the heat-sensitive recording medium. Thus, an image is recorded on the thermosensitive recording medium.

Therefore, according to the present invention, the laser signal light emitting means emits not the continuous wave laser light but the laser signal light modulated by the image data, so that the AOM for modulating the laser light is used. There is no need to use Therefore, the structure is simplified, and assembling adjustment is facilitated, so that productivity and workability are improved, and the cost is reduced. In addition, since the laser signal light directly modulated by the image data is used instead of the laser light modulated using the AOM, the rising speed is faster than the case where the laser light is modulated using the AOM. And the fall speed becomes faster. Therefore, the image recording speed can be improved.

In the image recording apparatus of the present invention, the image recording apparatus further comprises a superimposing means for superimposing the image data on a trigger signal having a fixed period, and the laser signal light emitting means comprises a pulse oscillation modulated by the image data. It is preferable to emit the laser signal light.

As described above, the laser signal light emitting means emits the pulsed laser signal light from the laser signal light emitting means, so that the heat-sensitive recording medium such as a thermal sensitive material is irradiated with the pulsed laser light. Is done. Therefore, the exposure intensity can be increased as compared with the conventional case of irradiating continuous oscillation laser light, so that highly efficient image recording can be performed. For example, when a laser having the same average output is used. In this case, image recording can be performed at a higher speed, and when the image recording speed is the same, a lower output laser can be used.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples. FIG. 1 is a configuration diagram showing an image recording apparatus as one embodiment of the present invention. As shown in FIG. 1, the image recording device 20 of the present embodiment mainly includes a laser signal light generating unit 22, a laser signal light amplifying unit 24, a drive / control unit 25, and an image recording unit 34. ing. The laser signal light generator 22 includes a signal semiconductor laser (LD; laser diode) 36 and a signal LD driver 38. Further, the laser signal light amplifying unit 24
It includes isolators 40 and 44, a preamplifier 42, a power amplifier 46, and an excitation LD driver 48.
In this embodiment, the laser signal light generating section 22 and the laser signal light amplifying section 24 constitute a fiber laser using an optical fiber as described later.

FIG. 2 is a block diagram showing a detailed configuration of the preamplifier 42 and the power amplifier 46 of FIG. As shown in FIG. 2, the preamplifier 42 and the power amplifier 46
Couplers 74 and 80 and excitation LDs 76 and 82, respectively.
And optical fibers 78 and 84.

In FIG. 1, the drive / control unit 25
Is a bitmap data memory 26 and a superimposing circuit 28
, A clock generator 30 and a control circuit 32. Further, the image recording unit 34 constitutes an output engine of an inner cylindrical system, and includes an optical fiber 49, a collimator lens 50, a condenser lens 52, a spinner mirror (deflection mirror) 54, a spinner motor 56, It includes an encoder 58, a transfer table 60, a transfer rod 62, a sub-scanning motor 64, an encoder 68, a drum 70, and a thermal sensitive material 72.

Next, the operation of this embodiment will be described with reference to FIGS. Image data to be image-recorded is pre-developed into bitmap data by a raster image processor (not shown) or the like, and then stored in the bitmap data memory 26. The bitmap data memory 26 sequentially reads out the stored image data according to a control signal from the control circuit 32, and inputs the read image data to the signal LD driver 38 in the laser signal light generator 22 via the superimposing circuit 28. Note that the superposition circuit 2
8 and the operation of the clock generator 30 will be described later in detail.

The signal LD driver 38 drives the signal LD 36 on the basis of the input image data, whereby the signal LD 36 emits a laser signal light modulated by the image data. Specifically, for example, when image data is at a high level, a laser beam is emitted (turned on),
At the low level, the laser beam is stopped (off). The laser signal light serves as a trigger for laser oscillation. As the signal LD 36, for example, an LD having a rating of about 10 mW is used.

The laser signal light emitted from the signal LD 36 is supplied to the isolator 4 in the laser signal light amplifier 24.
0, the preamplifier 42, the isolator 44, and the power amplifier 46 are sequentially guided to the optical fiber 49. Of these, the preamplifier 42 and the power amplifier 46 each constitute a fiber amplifier as shown in FIG.
The intensity of the incident laser signal light is amplified. These fiber amplifiers are provided with optical fibers 78 and 84 obtained by doping a part of a quartz optical fiber with elements such as erbium (Er) and ytterbium (Yb). The optical fibers 78 and 84 have high output power. By passing the laser pumping light emitted from the pumping LDs 76, 82, the atoms in the optical fibers 78, 84 are excited to increase their energy state, and a large population inversion (the number of atoms in the excited state is lower than the ground state). Distribution that is greater than the number of atoms). Then, by passing the laser signal light emitted from the signal LD 36 through the optical fibers 78 and 84, the laser signal light serves as a trigger to release the increased energy state and emit light. As a result, the laser signal light is amplified. The excitation LDs 76 and 82 are driven by the excitation LD driver 48 and always emit laser excitation light.

The wavelengths of the laser signal light amplified by these fiber amplifiers are, for example, optical fibers 78 and 84.
Is 1535 to 1580 nm when Er is doped, and 1060 to 11 nm when Yb is doped.
30 nm. In the present embodiment, the output power of the fiber amplifier is 5 W at the maximum, but the rated output of the pump LD is about 1 W. Therefore, a plurality of pump LDs are used as necessary.

Further, optical fibers 78 and 8 for laser excitation light
The light beam 4 is incident via couplers 74 and 80.
Here, when the LDs for pumping 76 and 82 are 1W-class LDs, the emitted laser pumping light is in the transverse mode, and should normally be incident on a multi-mode optical fiber.
Since the optical fibers 78 and 84 are single mode, special couplers 74 and 80 are used.

The laser signal light generating section 2 as described above
As the fiber laser configured by the laser signal light amplifier 2 and the laser signal light amplifying unit 24, for example, an EL series or YL series fiber laser provided by the IRE-POLUS group can be used.

On the other hand, in the image recording section 34, the collimator lens 50 converts the laser signal light guided via the optical fiber 49 into parallel light having a desired beam diameter, and converts the laser beam into the central axis of the cylindrical drum 70. Through the condenser lens 52. The condenser lens 52 condenses the incident parallel light and reflects it on the spinner mirror 54 to form a laser spot on the thermal photosensitive material 72 fixed on the inner peripheral surface of the drum 70. In this way, when the laser signal light modulated by the image data is irradiated on the thermal sensitive material 72,
In the thermal photosensitive material 72, a thermal reaction such as thermal ablation, melting, and sublimation occurs, and an image represented by image data is recorded on the thermal photosensitive material 72.

At this time, the spinner mirror 54 is
The laser spot is rotated by the spinner motor 56 in the direction around the central axis of the drum 70 to change the laser spot to the thermal photosensitive material 72.
The scanning is performed in the main scanning direction. On the other hand, the condenser lens 52,
The transfer table 60 on which the spinner mirror 54 and the like are mounted is driven by the sub-scanning motor 64 and moves along the transfer rod 62 arranged in parallel with the center axis of the drum 70, thereby moving the laser spot on the thermal photosensitive material 72. Scans in the sub-scanning direction. At this time, every time the spinner mirror 54 makes one rotation, the carrier table 60 moves by a desired distance, so that the laser spot scans the thermal photosensitive material 72 two-dimensionally.

An encoder 58 attached to the spinner motor 56 detects the timing of the main scanning of the laser spot, whereas an encoder 68 attached to the sub-scanning motor 64 detects the timing of the sub-scanning. doing. The control circuit 32 controls these encoders 58,
The detection signals from the controller 68 are input, and various control signals are generated based on the detection signals. One of the generated control signals is stored in the bitmap data memory 2 as described above.
6 controls the timing of reading image data from the bitmap data memory 26.

In this embodiment, the image data read from the bitmap data memory 26 may be directly input to the signal LD driver 38 to modulate the laser signal light only with the image data. as follows,
It is preferable that the image data is superimposed on the trigger signal using the clock generator 30 and the superimposing circuit 28, and the laser signal light is modulated by the obtained signal.

The clock generator 30 generates a trigger signal (for example, a sine wave signal) having a fixed period based on the control signal from the control circuit 32 and inputs the signal to the superimposing circuit 28. For example, the superimposition circuit 28 operates so as to output a trigger signal only during a period when the image data is at a high level, and not to output a trigger signal during a period when the image data is at a low level. Output to the driver 38. Since the signal LD 36 is driven by the trigger signal on which the image data is superimposed, the signal LD 36 generates a pulse oscillation and emits a pulsed laser signal light modulated by the image data. Specifically, for example, when the image data is at a high level, on / off (that is, pulse oscillation) of the laser beam is repeated at the same cycle as the trigger signal, and when the image data is at a low level, the laser beam is stopped.

Accordingly, when such pulsed laser signal light is incident on the fiber amplifier, the pump LDs 76 and 82 always emit laser excitation light in the fiber amplifier as described above. Even during the off-period of the oscillation laser signal light, the laser excitation light continuously excites the atoms in the optical fibers 78 and 84 to increase the energy state. Then, in the next ON period, the increased energy state is released at a stretch, so that a laser signal light having extremely high energy is emitted. For example, when the average power of the fiber laser is 3 W, the bit rate (modulation speed) is 100 MHz (time interval: 10 ns [corresponding to the cycle of the trigger signal]).
Assuming that the duration of the pulse oscillation (the time during which the laser is actually emitted) is 2 ns, the intensity (pulse intensity) of the pulsed laser signal light is 3 ÷ (2/10) = 1.
5W.

As described above, the pulsed laser signal light is emitted from the signal LD 36 and the intensity is amplified by the fiber amplifier, so that the laser signal light has very high energy. Exposure intensity when irradiating 72 is also very high.

By the way, in this embodiment, the change of the resolution of the recorded image at the time of performing the image recording can be realized by changing the amplification factor in the fiber amplifier. Specifically, the control circuit 32 controls the pumping LD driver 48, and controls the pumping LD 7 in the fiber amplifier.
This is performed by changing the intensity of the laser excitation light emitted from the light emitting devices 6, 82.

The thermal photosensitive material 72 used in this embodiment may be any photosensitive material having absorption characteristics at the wavelength of the laser signal light used. For example, a LAT (laser manufactured by Polaroid, USA) may be used. ablation transfe
r) A material using an ablation-type material such as a material is particularly suitable.

As described above, according to this embodiment,
Since the signal LD 36 in the laser signal light generating section 22 emits a laser signal light modulated by image data, it is not necessary to use an AOM or the like for modulating a laser light conventionally used. Therefore, since the configuration is simple and the assembly adjustment is easy,
The productivity and workability are improved, and the cost is reduced.

In addition, since the laser signal light directly modulated by the image data is used instead of the laser light modulated by using the AOM, compared with the case where the laser light is modulated by using the AOM. , The rising speed and the falling speed are increased. Therefore, the image recording speed can be improved, and in the recorded image,
Line breaks in the main scanning direction become sharp.

Further, since an LD having a relatively low output (about 10 mW) is used as the signal LD 36, the laser signal light is directly modulated with image data to achieve high speed (1).
(00 Mbps or more).

Further, in this embodiment, the clock generator 3
0 and the superimposing circuit 28, the signal LD
Since the laser signal light of pulse oscillation is emitted from 36 and the intensity thereof is amplified by the fiber amplifier and irradiates the thermal sensitive material 72, the exposure is performed in comparison with the conventional case of irradiating continuous oscillation laser light. The intensity can be increased and the exposure time can be shortened. In general, the thermal light-sensitive material 72 has the property that the sensitivity increases as the exposure intensity increases and the exposure time decreases (the thermal energy supplied to the thermal light-sensitive material 72 includes the laser signal light irradiation position). Thermal energy that escapes from
This is because it is considered that the shorter the exposure time is, the smaller the heat energy loss becomes). Therefore, by using the pulsed laser signal light as in this embodiment, highly efficient image recording can be performed. . That is, for example, when a laser having the same average output is used for image recording, higher-speed image recording can be performed, and when the image recording speed is the same, a lower-output laser can be used.

The present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the scope of the invention.

That is, in the above-described embodiment, the image recording unit 3
4, an internal cylinder type output engine is adopted, but the present invention is not limited to this. As shown in FIG. 3, an external cylinder type output engine is used as the image recording unit 34 '. May be used.

FIG. 3 is a block diagram showing an image recording apparatus when an output engine of an external cylinder type is used as an image recording section. In the image recording device 20 ′ shown in FIG. 3, an optical fiber 81, a carrier 83, a condenser lens 85, a carrier rod 86, a sub-scanning motor 88
, Encoder 90, drum 92, main scanning motor 9
4 and an encoder 96. In the image recording device 20 'shown in FIG. 3, the components other than the image recording unit 34' are the same as those in the image recording device 20 shown in FIG.

In the image recording section 34 ′ shown in FIG. 3, the condensing lens 85 condenses the laser signal light guided through the optical fiber 81, and fixes the laser signal light on the outer peripheral surface of the drum 92. A laser spot is formed on 98. At this time, the main scanning motor 94 rotates the drum 92 around the central axis, thereby causing the laser spot to scan on the thermal photosensitive material 98 in the main scanning direction. On the other hand, the carriage 83 on which the condenser lens 85 is mounted is
The laser spot is moved along the transport rod 86 arranged in parallel with the center axis of the drum 92 to scan the laser spot on the thermal photosensitive material 98 in the sub-scanning direction.

The encoder 96 attached to the main scanning motor 94 detects the timing of the main scanning of the laser spot, whereas the encoder 90 attached to the sub-scanning motor 88 adjusts the timing of the sub-scanning. Detected. The control circuit 32 controls these encoders 96 and 9
A detection signal from 0 is input, and various control signals are generated based on these detection signals.

Further, the present invention is not limited to the cylindrical output engine as shown in FIG. 1 or FIG. 3, and as shown in FIG. An output engine may be used.

FIG. 4 is a block diagram showing an image recording apparatus when an output engine of a plane scanning system is used as an image recording section. In the image recording device 20 ″ shown in FIG. 4, the image recording unit 34 ″ includes an optical fiber 100, a base 102, an auxiliary deflector 104, a collimator lens 106, a polygon mirror 108, an fθ lens 110, a roller 112
And thermal sensible material 114, mirrors 118 and 120,
A start sensor 122 and an end sensor 124 are provided. In the image recording device 20 "shown in FIG. 4, the components other than the image recording unit 34" are the same as those in the image recording device 20 shown in FIG.

4, the laser signal light guided through the optical fiber 100 is incident on the polygon mirror 108 via the auxiliary deflector 104 and the collimator lens 106. The polygon mirror 108
Is rotated at a constant speed in the direction of the arrow, and is sequentially reflected by eight mirrors attached to the outer peripheral surface to scan the incident laser signal light in a fan shape. The laser signal light reflected by the polygon mirror 108 is condensed by the fθ lens 110 and forms a laser spot on the thermal photosensitive material 114 wound around the roller 112.

Further, even outside the effective area of the image data, the laser beam is always emitted from the signal LD 36, and the laser beam is received by the start sensor 122 and the end sensor 124 via the mirrors 118 and 120, whereby 1 A start detection signal indicating the start timing of the main scan and an end detection signal indicating the end timing of one main scan are obtained. The control circuit 32 receives these detection signals, calculates the exposure time during one main scan from the start time and the end time of one main scan, and controls the timing of laser irradiation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an image recording apparatus as one embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a preamplifier 42 and a power amplifier 46 in FIG.

FIG. 3 is a configuration diagram illustrating an image recording apparatus when an output engine of an external cylinder type is used as an image recording unit.

FIG. 4 is a configuration diagram showing an image recording apparatus when an output engine of a plane scanning system is used as an image recording unit.

[Explanation of symbols]

 Reference Signs List 20 image recording device 22 laser signal light generating unit 24 laser signal light amplifying unit 25 driving / control unit 26 bitmap data memory 28 superimposing circuit 30 clock generator 32 control circuit 34 image recording unit 36 ... Signal LD 38 ... Signal LD driver 40,44 ... Isolator 42 ... Preamplifier 46 ... Power amplifier 48 ... Excitation LD driver 49 ... Optical fiber 50 ... Collimator lens 52 ... Condenser lens 54 ... Spinner mirror 56 ... Spinner motor 58 ... Encoder 60 ... Convey table 62 ... Convey rod 64 ... Sub-scanning motor 68 ... Encoder 70 ... Drum 72 ... Thermal sensitive material 74 ... Coupler 76 ... Exciting LD 78 ... Optical fiber 80 ... Coupler 81 ... Optical fiber 82 ... Exciting LD 83 ... Carrying table 84 ... Optical fiber 85 ... Condenser lens 86 ... Transport Rod 88 ... Sub-scanning motor 90 ... Encoder 92 ... Drum 94 ... Main scanning motor 96 ... Encoder 98 ... Thermal sensitive material 100 ... Optical fiber 102 ... Base 104 ... Auxiliary deflector 106 ... Collimator lens 108 ... Polygon mirror 110 ... Fθ lens 112: Roller 114: Thermal sensible material 118, 120: Mirror 122: Start sensor 124: End sensor

Claims (2)

[Claims] 1. An image recording apparatus that irradiates a thermosensitive recording medium with laser signal light modulated by image data to record an image represented by the image data on the thermosensitive recording medium, A laser signal light emitting means for emitting a laser signal light modulated by data; and an optical fiber doped with a predetermined element. The optical fiber is excited by laser excitation light, and then emitted to the optical fiber. An image comprising: a laser signal light amplifying unit that amplifies the intensity of the laser signal light through the obtained laser signal light; and a transmission unit that transmits the amplified laser signal light and irradiates the heat-sensitive recording medium. Recording device. 2. The image recording apparatus according to claim 1, further comprising a superimposing unit that superimposes the image data on a trigger signal having a fixed period, wherein the laser signal light emitting unit is modulated by the image data. An image recording apparatus that emits a pulsed laser signal light.