JPH03135269A - Picture recording device - Google Patents

Abstract

PURPOSE:To obtain a highly precise picture in a wide temperature range by applying a recording material having temperature dependency for sensitivity and providing an adjustment means adjusting the scanning speed of an optical beam by means of a beam deflector so that it compensates the fluctuation of sensitivity as against the temperature change of the recording material. CONSTITUTION:The recording material A has sensitivity in an infrared ray area and it has temperature dependency in sensitivity. A picture recording device 10 compensates the sensitivity change of the recording material A by a use environment temperature and it is provided with the adjustment means of the scanning speed of a resonant scanner 16 for executing picture recording with less density fluctuation, namely, less change of a dot area rate in any use environment temperature. Consequently, the dot area rate which is almost constant under any temperature condition can be obtained by adjusting the scanning speed of a recording beam 12a in correspondence with the change of the use environment temperature and adjusting an exposure quantity. Thus, the highly precise picture can be obtained in the wide temperature range.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image recording device. More specifically, the present invention relates to an image recording apparatus that can compensate for sensitivity changes in recording materials due to temperature changes.

<Prior Art> An image recording device that records an image by two-dimensionally scanning a recording material conveyed in the sub-scanning direction with a light beam reflected and deflected in the main-scanning direction is used in printing plate-making devices, copying devices, etc. It is applied for various purposes.

Such an image recording device reflects and deflects a light beam carrying image information emitted from a light source such as a semiconductor laser or a gas laser in the main scanning direction using an optical deflector such as a resonant scanner or a galvanometer mirror. A recording material, which is transported at a constant speed in a sub-scanning direction substantially orthogonal to the main-scanning direction, is two-dimensionally scanned and exposed by the light beam to record an image.

In other words, in such an image recording device, the frequency or intensity of the light beam is modulated according to the image information, or the light beam is turned on and off, and the light beam is two-dimensionally irradiated onto the recording material to expose it. , performs image recording.

Therefore, in order to record a good image that accurately reproduces the image density, etc., it is necessary to expose the recording material with an accurate exposure amount according to the image information.

<Problems to be Solved by the Invention> Incidentally, recording materials normally applied to such image recording apparatuses generally have temperature dependence in their sensitivity.

In other words, the sensitivity of ordinary recording materials tends to increase as the temperature rises; for example, when recording a halftone image,
Normally, the halftone area ratio changes by about 2% when the operating environment temperature is 10 tons and 30 degrees Celsius, and even if images are recorded with the same exposure, there will be a difference in the density of the resulting images. It will happen. This tendency is particularly strong in recording materials such as semiconductor lasers that are sensitive to infrared light (hereinafter referred to as infrared recording materials).

Therefore, in conventional image recording devices, especially those that use infrared recording materials, even if images are recorded with an accurate exposure amount according to the image information, the density of the image formed depends on the temperature of the usage environment. The images become different, which poses a problem for high-definition images.

An object of the present invention is to solve the problems of the prior art described above, and to record an image with a small density change, for example, a halftone dot area variation rate in a halftone image, even when an image is recorded in a wide temperature range. An object of the present invention is to provide an image recording device that can perform the following operations.

Means for Solving the Problems> In order to achieve the above object, the present invention provides a method for applying a two-dimensional image to a recording material moving in a sub-scanning direction substantially perpendicular to the main-scanning direction using a light beam deflected in the main-scanning direction. An image recording device that records an image in a digital manner, which uses a recording material whose sensitivity is temperature-dependent as the recording material, and includes a light source that emits a light beam with a wavelength in the infrared region, and a main scanning direction of the light beam. An image recording device comprising: a light deflector that deflects the light beam in the direction; and an adjustment means that adjusts the scanning speed of the light beam by the light deflector so as to compensate for fluctuations in the sensitivity of the recording material to temperature changes. Provide equipment.

Preferably, the optical deflector is a resonant optical deflector, and the adjusting means adjusts the scanning speed of the optical beam by adjusting the maximum vibration angle of the resonant optical deflector.

Further, it is preferable that the adjusting means is configured by using a magnet whose magnetic flux density is temperature-dependent as the driving magnet of the resonant optical deflector.

<Operation of the Invention> The image recording apparatus of the present invention has an adjusting means for adjusting the scanning speed of the optical deflector in accordance with changes in the sensitivity of the recording material due to changes in temperature.

In other words, depending on the operating environment temperature of the image recording device, when the temperature rises and the sensitivity of the recording material improves, by increasing the scanning speed of the light beam and reducing the exposure amount, the temperature can be lowered. When it becomes low, the scanning speed is reduced and the exposure amount is increased to reduce the use of the image recording device 3! Regardless of the ambient temperature, it is possible to always record a desired image density, such as a halftone image, with a small rate of variation in halftone dot area and good image recording.

Therefore, the image recording apparatus of the present invention does not require any particular temperature restrictions on the environment in which it is used, and can be used in a wide temperature range, and can be suitably applied to various uses.

<Embodiments> Hereinafter, an image recording apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 shows a schematic diagram of a preferred embodiment of the image recording apparatus of the present invention.

The image recording device 10 shown in FIG. 1 is a halftone dot character/line image recording device that applies raster scanning, and includes:
Basically, a recording laser beam 12 with a wavelength in the infrared region
a recording unit 12 that emits a recording beam 12a (hereinafter referred to as a recording beam 12a), a grating unit 14 that emits a grating laser beam 14a (hereinafter referred to as a grating beam 14a), and a resonant scanner 16 that is an optical deflector. An fθ lens 18, an exposure drum 20 for holding the recording material A in a predetermined position, nip rollers 22 and 24 that nip and convey the recording material A together with the exposure drum 20, and a length that reflects the grating beam 14a in a predetermined direction. It is composed of a length mirror 26, a grating 28 and a condensing bar 30, which are image synchronization signal generating means.

Further, the recording material A applied to the image recording apparatus 10 of the present invention has sensitivity in the infrared region, and has temperature dependence in sensitivity.

In such an image recording apparatus 10, the recording beam 12a and the grating beam 14a emitted from each light beam unit are reflected and deflected in the main scanning direction indicated by arrow a by the resonant scanner 16, and then reflected and deflected by the fθ lens 18. The recording beam 12a is adjusted to form a predetermined beam spot on the recording material A, and the recording beam 12a is conveyed by the exposure drum 20 and the nip rollers 22 and 24 in the sub-scanning direction indicated by the arrow.
An image is formed on the surface, and the image is recorded by scanning and exposing the image two-dimensionally.

On the other hand, the grating beam 14a is reflected by the long mirror 26 and scans the grating 28, and the position detection signal of the recording beam 12a,
In other words, it is an image synchronization signal.

The image recording apparatus 10 of the present invention, which basically has the above-mentioned configuration, compensates for the sensitivity change of the recording material A due to the usage environment temperature, and maintains halftone dots with little density fluctuation at any usage environment temperature. It has means for adjusting the scanning speed of the resonant scanner 16 in order to record an image with little change in area ratio.

Recording materials usually have a temperature dependency in which sensitivity increases as the temperature of the environment in which they are used rises, and this tendency is particularly high in recording material A, which is used in the present invention and has sensitivity in the infrared region.

The image recording apparatus 10 of the present invention can maintain a substantially constant halftone dot area ratio under any temperature conditions by adjusting the scanning speed of the recording beam 12a and adjusting the exposure amount according to changes in the operating environment temperature. It is possible to obtain.

In the illustrated apparatus, the scanning speed of the recording beam 2a is adjusted by adjusting the maximum torsion angle of the resonant scanner 16 (mirror 34 of the resonant scanner 16) while keeping the main scanning frequency of the light beam constant. Let's do it.

In other words, for example, when the operating environment temperature rises, the maximum twist angle is increased, the main scanning speed of the recording beam 12a is increased, and the exposure amount is decreased, thereby responding to the increase in sensitivity of the recording material A. Therefore, the dot area ratio is kept constant.

Note that when the scanning speed is adjusted by adjusting the maximum twisting angle, the speed does not change uniformly over the entire scanning line, but the rate of change in the scanning speed increases as the twisting angle increases.

That is, when the torsion angle of the resonant scanner 16 is θ, the maximum torsion angle is θ, 1X, and the angular frequency is ω, the torsion angle θ is θ=θmmxsinωt, and the scanning speed V is 2;θwaxωcosωt. Therefore, we obtain.

Here, for example, when the maximum torsion angle θff1llX is 24 degrees and the image recording area is 20 degrees, then the torsion angle is 0''
'' position and the 20° position, the rate of change in scanning speed is 3.27 times greater at the 20° position, and it is not possible to keep the rate of change in the scanning speed constant in all areas. .

However, according to the inventor's study, this rate of change is 1 d s d θ□x
d s3.27 dT
By adjusting the dT within the range of dT, it is possible to compensate to some extent for sensitivity changes due to changes in the environment temperature in which recording material A is used, and to reduce fluctuations in the dot area ratio by 1.
% or less.

The recording unit 12 emits a recording beam 12a, and is configured by integrally uniting a semiconductor laser that emits a recording light beam and a collimator lens that shapes the laser beam emitted from the semiconductor laser. It is something that In addition. In the present invention, the light source of the recording beam 12a is not limited to a semiconductor laser as long as it is capable of emitting a light beam having a wavelength in the infrared region, and various sources such as an LED can be used. .

On the other hand, the grating unit 14 emits a grating beam 14a, and has basically the same configuration as the recording unit 12 described above, and includes a semiconductor laser as a grating scanning light beam source and a grating beam emitted from the semiconductor laser. A collimator lens for shaping a laser beam is integrated into a unit.

The recording beam 12a and grating beam 14a emitted from the respective light beam units then enter the resonant scanner 16, where they are reflected and deflected in the main scanning direction indicated by arrow a.

The image recording apparatus 10 of the present invention has means for adjusting the scanning speed of the recording beam 12a in order to compensate for changes in the sensitivity of the recording material A due to changes in the operating environment temperature. In this apparatus, the scanning speed is adjusted by adjusting the maximum twist angle of the resonant scanner 16 in accordance with changes in the operating environment temperature.

A schematic diagram of this resonant scanner 16 is shown in FIG.

As shown in FIG. 2, a control circuit 32 is connected to the resonant scanner 16 to control its driving.

In such a resonant scanner 16, a mirror 34 for reflecting each light beam (recording beam 12a and grating beam 14a) is fixed to a rotor 36. This rotor 36 has leaf springs 38 and 40 and a leaf spring 42.
and 44 are fixed to each form a cross shape, and each leaf spring is fixed to a housing 46 to support the rotor 36.

Furthermore, a cylindrical magnet 50 is fixed to the right side of the rotor 36 in the figure via a fixing member 48. Further, the magnet 50 is inserted into the spatula 52 with a slight gap.

Here, in the illustrated resonant scanner 16,
In order to constitute means for adjusting the scanning speed of the recording beam 12a, the magnet 50 has a characteristic that the magnetic flux density decreases as the temperature rises. This magnet 5
The effect of 0 will be explained in detail later.

A drive coil 54 and a pickup coil 56 are arranged in the head 52 as conceptually shown in FIG. 3, and the magnet 50 and the drive coil 54 form a motor that moves the resonant scanner 16.

Such a resonant scanner 16 rotates the magnet 50 in the direction of arrow C by passing an alternating current through the drive coil 54, that is, by a motor made up of the magnet 50 and the drive coil 112, and rotates the magnet 50 in the direction of arrow C. The system consisting of the rotor 36 including the springs 42 and 44 and the mirror 34 is set in a resonant state, and the rotor 36 is swung greatly, and the mirror 34 is swung in the direction of arrow d to reflect and deflect the light beam in the main scanning direction. It is something to do.

Furthermore, the torsion angle of the mirror 34 is detected by detecting the electromotive force generated in the pickup coil 56 due to a change in magnetic flux density due to the rotation of the magnet 50.

A control circuit 32 is connected to the drive coil 54 and pickup coil 56 of the resonant scanner 16, and the drive of the resonant scanner 16 is controlled.

The pickup coil 56 is connected to a waveform shaper 58 , and the output from the pickup coil 56 is waveform-shaped and sent to a pickup coil output amplifier 60 . This pickup coil output amplifier 60 is connected to a peak hold circuit 62 and a phase compensation circuit 64.

A reference voltage 66 for adjusting the maximum torsional angle of the mirror 34 of the resonant scanner 16 is a peak voltage value (corresponding to the amplitude of the motor, that is, the maximum torsional angle of the mirror 34) detected by this peak hold circuit 62. ) and the difference is sent to the PID controller 68.

This voltage value is subjected to PID calculation by the PID controller 68 to a voltage value of the torsion angle correction amount of the resonant scanner 16, and then sent to the multiplier 7°.

On the other hand, the pickup output voltage signal sent from the pickup coil output amplifier 6o to the phase compensation circuit 64 is compensated for the phase shift caused by waveform shaping, amplification, etc., and then sent to the multiplier 70.
sent to.

In the multiplier 70, the phase-compensated pickup output signal is multiplied by the torsion angle positive voltage value from the PID controller 68 and combined to provide an output current that can obtain the appropriate maximum torsion angle drive current to the output amplifier 72. The drive current is sent to the drive coil 54, is amplified by the output amplifier 72, and a drive current with an appropriate maximum twist angle is applied to the drive coil 54.

Here, the image recording device 10 adjusts the maximum twist angle of the resonant scanner 16 according to the operating environment temperature, adjusts the scanning speed of the light beam, and compensates for the temperature dependence of the sensitivity of the recording material A. Therefore, a magnet 50 whose magnetic flux density is temperature dependent is used.

In other words, in the illustrated device, by using a magnet 50 whose magnetic flux density decreases as the temperature rises, the pickup coil 56 responds to temperature changes.
The maximum torsion angle of the mirror 34 is changed in accordance with temperature changes.

As mentioned above, in this control circuit 32, the maximum value of the induced electromotive voltage of the pickup coil 56 sent from the pickup coil output amplifier 60 and the base! $! The torsional angle correction amount of the drive current to be applied to the drive coil 54 is set by comparing it with the voltage 66.

Here, when the magnet 50 having the characteristics described above is used, even if the rotation angle of the magnet 50 is constant, the induced electromotive voltage generated in the pickup coil 56 decreases as the temperature rises. In other words, even if the maximum torsion angle of the mirror 34 is constant, the maximum value of the induced electromotive force generated in the pickup coil 56 and detected by the peak hold circuit 62 decreases, which is similar to the state in which the maximum torsion angle becomes small. , and the difference from the reference voltage 66 becomes large.

Therefore, the voltage value of the Shishin angle correction amount that is PID-calculated by the PID controller 68 becomes a value that increases the maximum torsion angle of the mirror 34 as the temperature rises, and the maximum torsion angle of the mirror 34 of the resonant scanner 16 increases with temperature. It can be increased as it rises.

Here, since the frequency of light beam scanning by the resonant scanner 16 is constant, as the temperature rises, the mirror 34
By increasing the maximum twist angle of the recording material HA, the scanning speed of the light beam can be increased as the temperature rises, and the exposure amount can be adjusted to compensate for the temperature dependence of the sensitivity of the recording material HA.

The temperature dependence characteristics of the magnet 50 may be appropriately selected to suitably compensate for the temperature dependence of the sensitivity of the recording material A, depending on the applied recording material A and the resonant scanner 16. Generally, for example, a magnetic flux density having a temperature dependence of about -0.05%/°C is used.

Specifically, preferred examples of magnets having such temperature dependence include neodymium-boron magnets, samarium-cobalt magnets, and MS materials bonded as magnetic shunt materials.

FIG. 4 shows a resonant scanner that is applicable to the image recording apparatus 10 of the present invention and has an adjusting means for adjusting the scanning speed of the light beam by adjusting the swing angle of the mirror 34 according to changes in the operating temperature. Another example is shown.

The resonant scanner 74 shown in FIG. 4 uses a normal permanent magnet as the magnet 76 of the drive motor, and is equipped with a separate temperature sensor 78 to detect the temperature of the usage environment and feed back the result to determine the maximum torsion angle. This is to adjust the

Here, the resonant scanner 74 is basically the same as the above-mentioned resonant scanner, except that an ordinary permanent magnet is used as the magnet 76, a temperature sensor 78 is provided, and a control circuit 80 includes a processing system for the signal from the temperature sensor 78. Since it is similar to the scanner 16, the same members are given the same numbers and their explanations will be omitted.

In the resonant scanner 74 , the temperature output signal detected by the temperature sensor 78 is amplified by the temperature sensor output amplifier 82 and sent to the temperature coefficient adjustment circuit 84 .

The output signal of the temperature sensor is adjusted by the temperature coefficient adjustment circuit 84 according to a correction coefficient set according to the temperature dependence of the recording material A and the temperature dependence of the magnet 76, and is detected by the peak hold circuit 62. The peak voltage value is compared with a reference voltage 66, and the difference is determined as PI.
It is sent to the D controller 68 and then sent to the resonant scanner 7.
PID calculation is performed on the voltage value of the torsion angle correction amount of 4, and then sent to the multiplier 70.

In this way, the resonant scanner 74 shown in FIG. 4 adjusts the maximum torsion angle in the same way as the resonant scanner 16 described above by feeding back the detection results of the temperature sensor 78, and adjusts the maximum torsion angle according to the operating environment temperature. This adjusts the scanning speed of the beam.

The preferred location for installing the temperature sensor 78 is near the sub-scanning conveyance means for the recording material A, but there is no particular limitation, and the location may be determined as appropriate depending on the configuration of the image recording device 10, such as the housing 46 of the resonant scanner 74, for example. Bye.

In addition to the above-mentioned resonant scanner that can adjust the torsion angle and is applicable to the present invention, the maximum torsion angle can be adjusted by using an element whose output is temperature dependent in the control circuit 32. It may also be something that adjusts the scanning speed.

Each light beam whose scanning speed is adjusted by the resonant scanner 16 and is reflected and deflected is then passed through the fθ lens 18.
It is adjusted so that the beam is incident on the beam and is imaged at a predetermined position with a predetermined beam spot shape.

The grating beam 14a that has passed through the fθ lens 18 is reflected upward by a long mirror 26 and scans the grating 28.

The grating beam 14a that has passed through the grating 28 is directed to the condensing bar 30.
The light is focused by the photo multiplier.
The light is measured by a photodetector 86 such as , and converted into an electrical signal.

The grating beam 14a incident on the grating 28 is reflected in the main scanning direction shown by the arrow C by the resonant scanner 16 in exactly the same way as the recording beam 12a scanning the recording material A.
It is biased. Therefore, a synchronization signal for detecting the accurate position of the recording beam 12a can be obtained from an electric signal obtained from periodic changes in light intensity in accordance with the scanning of the grating 28 by the grating beam 14a, and from this synchronization signal. The main scanning of the recording beam 12a on the recording material A can be made more precise.

On the other hand, the recording beam 12a that has passed through the fθ lens 18 is
While being held at a predetermined image recording position by the exposure drum 20 and nip rollers 22 and 24, an image is formed on the recording material A that is nipped and conveyed in the sub-scanning direction indicated by the arrow, so that the recording material A is two-dimensionally The image is recorded by scanning exposure.

The above-described image recording device 10 uses the resonant scanner 16 (resonant scanner 74) as an optical deflector, and adjusts the maximum torsion angle while keeping the main scanning frequency constant, thereby adjusting the main scanning speed of the light beam according to the temperature. However, the present invention is not limited to this,
For example, by using a galvanometer mirror as an optical deflector and adjusting the maximum torsion angle while keeping the frequency constant,
The main scanning speed may be adjusted in accordance with temperature changes to compensate for changes in sensitivity due to temperature of the recording material A.

Furthermore, when using a galvanometer mirror as an optical deflector, by adjusting the frequency of its oscillation,
When a polygon mirror is used as the optical deflector, the scanning speed may be adjusted in accordance with temperature changes by adjusting the rotation speed, thereby compensating for changes in sensitivity due to temperature of the recording material A. However, in this case, since the main scanning cycle changes depending on the temperature, the sub-scanning conveyance speed also needs to be changed accordingly.

As above, the image recording apparatus according to the present invention has been described in detail based on the preferred embodiments shown in the attached drawings, but the present invention is not limited thereto, and within the scope of not changing the gist of the present invention, Of course, various modifications and improvements are possible.

<Effects of the Invention> As explained in detail above, the image recording device of the present invention has the following effects:
It has an adjustment means that adjusts the scanning speed of the optical deflector according to changes in the sensitivity of the recording material due to temperature changes. For example, depending on the operating environment temperature of the image recording device, the temperature increases and the sensitivity of the recording material increases. In this case, by increasing the scanning speed of the light beam and decreasing the exposure amount, the desired image density is always maintained, for example, in the case of a halftone image, regardless of the operating environment temperature of the image recording device. Less area fluctuation rate,
Good image recording can be performed.

Therefore, the image recording apparatus of the present invention does not need to particularly limit the environmental temperature in which it is used, and can be applied in a wide temperature range, and can be suitably applied to various uses.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of an example of an image recording apparatus according to the present invention. FIG. 2 is a conceptual diagram of a resonant scanner applied to the image recording apparatus shown in FIG. 1. FIG. 3 is a diagram conceptually showing the head section of the resonant scanner shown in FIG. 2. FIG. 4 is a conceptual diagram of another example of a resonant scanner applicable to the image recording apparatus shown in FIG. 1. Explanation of symbols 10... Image recording device, 12... Recording unit, 12a... Laser beam for recording, 14... Grating unit, 14a... Laser beam for grating, 16.74... Resonant Scanner, 18...fθ
Lens, 20... Exposure drum, 22.24... Nip roller, 26... Long mirror 28... Grid, 30... Focusing bar 32.80... Control circuit, 34... Mirror 36...Rotor, 38.40, 42.44...Plate (ne), 46...Housing, 48...Member, 5076...Magnet, 52...Head, 54... Drive coil, 56...Pickup coil, 58...Waveform shaper 60...Pickup coil output amplifier, 62...
Peak hold circuit, 64... Phase compensation circuit, 66... Reference voltage, 68... PID controller, 70... Multiplier, 72... Output amplifier, 78... Temperature sensor, 82...・Temperature sensor output amplifier, 84... Temperature coefficient adjustment circuit, A... Recording material

Claims (1)

[Claims] (1) An image recording device that records an image two-dimensionally on a recording material moving in a sub-scanning direction substantially perpendicular to the main-scanning direction with a light beam deflected in the main-scanning direction, the recording material having a sensitivity A recording material having a temperature dependence is applied to the recording material, a light source that emits a light beam with a wavelength in the infrared region, an optical deflector that deflects the light beam in the main scanning direction, and a recording material that is sensitive to temperature changes. An image recording apparatus comprising: adjustment means for adjusting the scanning speed of the light beam by the optical deflector so as to compensate for fluctuations.