JPS63317347A - Light beam scan recording device and its control - Google Patents

Abstract

PURPOSE:To correct the unevenness of an exposure value and form a high quality image by creating data for controlling the amount of exposure in accordance with the characteristics of an optical system for scanning by light beam and adjusting the amount of exposure based on an image signal and control data corresponding to image information. CONSTITUTION:Laser beam L1 which is output from a laser diode 12 for recording is limited to become a parallel flux by a collimator and reflected into a resonance light reflector 22. The resonance light reflector 22 oscillates at high rate by means of a sinusoidal drive current, and projects laser beam L1 on a main scanning line 48 of film F through a ftheta lens 24. The film F is subscanned and transported to a B direction, held between a drum 26 and nipple rollers 27a, 27b, and a halftone dot image is bidimensionally formed on the film F by the laser beam for recording L1. The laser beam for recording L1 has a positional variation value such as optical characteristics and scanning rate corrected precisely by control data stored in a control information memory 42 to form a high quality image without exposure irregularity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light beam scanning recording device and a control method therefor, and more particularly, the present invention relates to a light beam scanning recording device and a control method thereof, and more particularly, to a method for scanning a record carrier such as a film at high speed to record character information, image information, etc. The present invention relates to a light beam scanning recording device and a control method thereof, which make it possible to avoid exposure unevenness by correcting the light amount of a recording light beam according to the characteristics of an optical system, the scanning speed on the record carrier, etc.

[Background of the Invention] For example, in the fields of printing and plate-making, image scanning, recording and reproducing is used to electrically process image information carried on a manuscript and create a film master for the purpose of streamlining work processes, improving image quality, etc. The system is widely used.

This image scanning recording/reproducing system basically consists of an image reading device and an image recording device. In other words, in the image reading device, the image information of the document that is conveyed in the sub-scanning direction in the image reading section is main-scanned by a photoelectric conversion element and converted into an electrical signal, which is then subjected to arithmetic processing such as gradation correction and edge enhancement according to the plate-making conditions. will be applied. Next, the image information subjected to photoelectric conversion and arithmetic processing in the image reading device is converted into an optical signal of a laser beam in an image recording device, and is recorded and reproduced on a record carrier made of a photosensitive material such as a film. . In addition,
This recording carrier is developed by a predetermined developing device and used as a film original for printing or the like.

Here, in order to achieve miniaturization, cost reduction, and high reliability of the image recording device, it is necessary to use ν-
It is desirable to use the diode. In this case, the laser beam output from the laser diode is usually made into parallel light by a collimator lens, then deflected by a swinging galvanometer mirror, and then directed to the main scanning direction on the record carrier via a θ lens. It is irradiated.
The fθ lens is small and lightweight, and achieves the function of scanning the laser beam deflected by the galvanometer mirror at a constant speed in the main scanning direction of the record carrier.

Incidentally, in order to improve the processing speed of image information in an image recording apparatus, it is desired to scan a record carrier with a laser beam at a higher speed. Therefore, as a device that can achieve this high-speed scanning, there is a resonant optical deflector that swings a mirror at high speed using the natural vibration of an elastic member. In this case, since the resonant optical deflector performs a sinusoidal vibration operation, the scanning speed is kept constant when the laser beam is irradiated onto the record carrier through the arcsine lens. However, this arcsine lens is larger than the fθ lens, and has the disadvantage that the spot diameter of the laser beam increases at both ends of the main scanning line on the record carrier.

Therefore, in order to achieve high-speed scanning while maintaining the miniaturization of the device, it is conceivable to combine the resonant optical deflector with an fθ lens. In this case, since the resonant optical deflector has sinusoidal vibration characteristics, there arises a problem that the scanning speed of the laser beam on the record carrier cannot be controlled to a constant level by the fθ lens. That is, the laser beam irradiated onto the record carrier has a high scanning speed at the center of the main scanning line and a slow scanning speed at both ends. Therefore, the exposure time at both ends of the main scanning line is It has been pointed out that there is a drawback that the length of the recording medium becomes longer than the length of the recording medium, resulting in unevenness in the exposure amount of images recorded on the recording carrier. In particular, when reproducing an image with a wide width in the main scanning direction, the deterioration of the image quality on the record carrier becomes even more noticeable.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned disadvantages, and the present invention has been made in order to overcome the above-mentioned disadvantages. A light beam scanning recording capable of correcting non-uniformity in the amount of exposure caused by the light beam and forming a high-quality image by controlling the light beam onto the record carrier based on data set in consideration of the above factors. The purpose of the present invention is to provide a device and a control method thereof.

[Means for achieving the object] In order to achieve the above object, the present invention provides a light beam scanning recording device that scans a record carrier with a light beam to record character information, image information, etc. a scanning optical system, an image signal generating means for generating an image signal corresponding to the image information, and a control data storage means for storing control data for controlling the amount of light beam according to the characteristics of the scanning optical system; The apparatus is characterized by comprising a light amount adjusting means for adjusting the light amount of the light beam based on the image signal and the control data.

Further, the present invention scans a record carrier with a light beam to obtain character information.
When recording image information, etc., control data is created to control the light intensity of the light beam according to the characteristics of the scanning optical system that scans the light beam, and then an image signal corresponding to the image information, etc. and the control data are recorded. The light intensity of the light beam is adjusted based on the light intensity.

[Embodiments] Next, preferred embodiments of the light beam scanning recording device and the control method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a main body of a light beam scanning recording apparatus according to the present invention, and this main body 10 includes a recording laser diode 12 that outputs a recording laser beam, and a recording laser diode 12 that outputs a recording laser beam L2. It includes a synchronizing laser diode 14 for outputting.

In this case, the recording laser diode 12 is driven and controlled by the output control circuit 16. On the other hand, the synchronizing laser diode 14 is driven by a drive circuit 18.

Laser light L output from recording laser diode 12
+ is made into a parallel light beam by a collimator 20, and a resonant optical deflector 22 and an fθ lens 24 swing in the direction of the arrow.
Main scanning is performed on the rotating drum 26 in the direction of arrow A. The drum 26 has a pair of nip rollers 27a, 27b on which the film F to be sub-scanned and conveyed in the direction of arrow B is attached.
Sliding contact is made while being held between the two.

On the other hand, the synchronizing laser beam L2 output from the synchronizing laser diode 14 is made into a parallel beam by the collimator 28, and is irradiated onto the grid 30 via the resonant optical deflector 22 and the rθ lens 24.

In this case, the grid 30 is provided in the main scanning direction (six arrow directions).
Transmissive portions 32a and non-transmissive portions 32b are alternately formed along the grid 30, and a condensing rod 34 is disposed on the back side of the grid 30. Note that photodetectors 36a and 36b are arranged at both ends of the condensing rod 34, and output signals from these photodetectors 36a and 36b are supplied to the output control circuit 16.

Here, the output control circuit 16 that controls the recording laser diode 12 is configured as shown in FIG. That is, the output control circuit 16 outputs the image information read from the document into two
Image signal generation circuit 3 that converts into a valued halftone image signal
8, a frequency multiplication PLL circuit 40 that outputs a synchronization signal on the third day of the image signal generation circuit, a control information memory 42 that has corrected control data and outputs a control signal based on the synchronization signal, and the control information memory 42 that outputs a control signal based on the synchronization signal. A D/A converter 44 that converts a signal into an analog signal, and a drive that drives the recording laser diode 12 with the control signal based on the halftone image signal from the image signal generation circuit 38 to output the recording laser beam L1. It basically consists of a circuit 46.

The light beam scanning recording device of this embodiment is basically constructed as described above, and its operation and effects will be explained next.

First, a method for creating control data stored in the control information memory 42 will be explained.

In FIG. 3, if one point on the main scanning strip 48 of the film F is exposed to the recording laser beam at an illuminance I for L hours, the exposure amount at that point is E=lt,...( 1). In this case, if a spot 50 with a diameter d caused by the recording laser beam moves at a scanning speed V along the main scanning line 48, the exposure iE of one point on the main scanning line 48 is the light of the spot 50. Assuming that the intensity distribution is uniform, E=I・□...(2)■. Here, the amount of light emitted by the recording laser beam output from the recording laser diode 12 is P, and the transmission efficiency of the recording laser beam by the optical system consisting of the collimator 20, the resonant optical deflector 22, and the fθ lens 24 is assumed to be P. η
Then, equation (2) becomes E=P・η・□
...(3) ■. Therefore, if the transmission efficiency η of the optical system, the diameter d of the spot 50, and the positional change of the scanning speed V on the main scanning line 48 are known, the emitted light IP of the recording laser diode 12 can be controlled accordingly. The exposure IE for the main scanning line 48 on F can be set to a desired amount. Note that although equations (1) to (3) assume that the light intensity distribution of the spot 50 on the film F is uniform, it is easily understood that almost the same consideration can be made using a Gaussian distribution. Good morning.

Here, the positional changes in the transmission efficiency η of the optical system, the diameter d of the spot 50, and the scanning speed V are specifically based on the following causes.

That is, as shown in FIG. 4, the reflectance r of the resonant optical deflector 22 varies depending on the incident angle φ of the recording laser beam L1 on the deflection mirror surface. Furthermore, the amount of loss of the recording laser beam L1 due to the fθ lens 24 is as shown in FIG.
It varies depending on the deflection angle θ due to changes in the optical path length, reflection at the lens interface, etc.

On the other hand, the diameter d of the spot 50 formed on the film F
It is extremely difficult to maintain a constant value over the entire area of the main scanning line 48. For example, when using the fθ lens 24, the beam of diameter d in the main scanning direction with respect to the deflection angle θ of the recording laser beam L1 is extremely difficult to maintain. The diameter thickening ratio Δ has the characteristics shown in FIG.

Furthermore, in order to simultaneously achieve high-speed scanning of the recording laser beam L1 and miniaturization of the apparatus, a combination of a resonant optical deflector 22 and an fθ lens 24 is used in this embodiment. In this case, since the resonant optical deflector 22 is driven by a sine wave corresponding to its natural frequency, it can deflect the recording laser beam at a higher speed than the galvanometer mirror. However, the scanning speed V varies depending on the sine wave, and for example, is slow at both ends of the main scanning line 48 (and fast at the center).

Therefore, considering the above-mentioned change factors, the values η of η, d, and ■ when the deflection angle of the deflector is 0 degrees are determined. , do, and vo are calculated or actually measured as functions of the scanning position y of the recording laser beam along the main scanning direction. Here, when the exposure amount E is constant, the correction ratio ΔP of the emitted light amount P of the recording laser diode 12 is:
Based on equation (3), Δη(y) as a function of scanning position y
・Δd(y) ...(4) Here, k is an arbitrary constant depending on the output of the recording laser diode 12. Therefore, the emitted light fJP
Recording laser diode 12 with Po・ΔP(y)
The control data L(y) of L(y) = kz・P
o・ΔP(y)...Set as (5). Here, 2 is an arbitrary constant that determines the relationship between the control data L(y) and the output of the recording laser diode 12.

The control data L(y) set in this way is stored in the control information memory 42 shown in FIG.

Next, an exposure test is performed using the control data L(y) set as described above. In this case, the image signal generation circuit 38 is set to supply the drive circuit 46 with a high-level signal for enabling the drive circuit 46 or a control j1 signal of 0N10FF for generating halftone dots of an arbitrary percentage. I'll keep it. Therefore, the drive circuit 46 is operated based on the control data L(y) stored in the control information memo i month 2, and the recording laser diode 12 outputs recording laser light. This recording laser beam is collimated into a parallel beam by a collimator 20, enters a resonant optical deflector 22, and is then irradiated onto the main scanning line 48 of the film F via an fθ lens 24. As a result, the film F receives the control data L(y) from the control information memory 42.
A test pattern is formed by exposure based on the .

Next, the density distribution of the test pattern thus formed is measured along the main scanning line 48.

Here, if the concentration fluctuation ΔD(y) is detected, (5)
The control data L(y) of the formula is L(y) = k3・L"(y)/ΔD(y)
...Modify as shown in (6) and use this control data L (
y) is stored in the control'+TII information memory 42. Here, L'(y) is the control data before modification, and k3 is an arbitrary constant depending on the output of the recording laser diode 12.

Next, the exposure test is performed again, and the control data L(y) is set so that the density distribution on the main scanning line 48 is constant.

After obtaining the control data L(y) as described above and storing it in the control information memory 42, an image recording operation is performed on the film F.

Therefore, the synchronization laser diode 14 is driven under the action of the drive circuit 18, and the synchronization laser light L2 is output.

This synchronizing laser beam L2 is made into a parallel beam by the collimator 28, and then enters the resonant optical deflector 22. The resonant optical deflector 22 is oscillating at high speed, and the synchronizing laser beam L2 reflected by the resonant optical deflector 22 is fθ
The light is irradiated onto the grid 30 through the lens 24. In this case, transparent parts 32a and non-transparent parts 32b are alternately formed in the grid 30 in the main scanning direction (direction of arrow A), and the synchronizing laser beam L2 transmitted through the transparent parts 32a is transmitted as a pulse signal. Light detector 3 from condensing rondo 34
6a and 36b. Next, the pulse signal is converted into a synchronization signal of a predetermined pitch by a frequency multiplication PLL circuit 40.

On the other hand, the image signal generation circuit 38 converts predetermined image information into a halftone image signal, and uses this halftone image signal to multiply the frequency by P.
Based on the synchronization signal output from the LL circuit 40, the drive circuit 46 is placed into an operating state or a non-operating state. here,
The control data stored in the control information memory 42 is output to the D/A converter 44 based on the synchronization signal and converted into an analog signal. Next, this analog signal drives the drive circuit 46 only when a high-level halftone image signal is output from the image signal generation circuit 38, and causes the recording laser diode 12 to output the recording laser beam L1.

In this case, the amount of light emitted P from the recording laser diode 12 is accurately adjusted by the control data output from the control information memory 42.

The recording laser beam L1 output from the recording laser diode 12 is made into a parallel beam by the collimator 20, and then enters the resonant optical deflector 22.

Here, the resonant optical deflector 22 is oscillated at high speed in the direction of the arrow by a sine drive current, and the recording laser beam L1
is irradiated onto the main scanning line 48 of the film F through the fθ lens 24. On the other hand, the film F is being fed in the sub-scan V direction in the direction of the arrow B while being sandwiched between the drum 26 and the nip rollers 27a and 27b.
A two-dimensional halftone image is formed on the top by recording laser light. In this case, the optical characteristics of the recording laser beam, the amount of positional variation such as scanning speed, etc. are accurately corrected by the control data stored in the control information memory 42, so that high-quality images without uneven exposure can be obtained. will be formed.

Here, in the embodiment described above, a case has been described in which image information is converted to a halftone image signal and recorded on the film F, but it is also possible to have a configuration in which image information is recorded based on a continuous tone image signal. It is. That is, in the output control circuit 51 shown in FIG.
The control data output from the control information memory 42 in the operational amplifier 54 and converted into an analog signal by the D/A converter 44 is multiplied by the analog image signal to generate a drive circuit. 46. In this case, a continuous tone image is formed on the film F.

Furthermore, in the output control 1 circuit 56 shown in FIG. It is also possible to generate a drive signal in combination, convert this drive signal into an analog signal by the D/A converter 62, and drive the drive circuit 46. In this case, a substantially continuous tone image similar to the continuous tone image formed by the output control circuit 51 shown in FIG. 7 is formed on the film F.

[Effects of the Invention] As described above, according to the present invention, a laser beam output from a laser diode is irradiated onto a record carrier through a resonant optical deflector and an fθ lens, and character information, image information, etc. When recording, the laser beam is corrected and output based on control data set in consideration of the scanning speed of the resonant optical deflector, the irradiation efficiency of the laser beam onto the record carrier, and the like. Therefore, exposure unevenness due to positional changes with respect to the record carrier, such as scanning speed and irradiation efficiency, is effectively corrected, and a high-quality image can be formed. In addition, high-quality images can be obtained simply by adjusting the control data in response to replacement of parts that make up the optical system of the device or changes in the output of the laser diode over time, making maintenance of the device extremely easy. It has the advantage of being inexpensive.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the main body of a light beam scanning recording device according to the present invention; FIG. 2 is a block diagram showing the configuration of an output control circuit in the light beam scanning recording device according to the present invention; FIG. 3 is an explanatory diagram of the light beam control method according to the present invention, FIGS. 4 to 6 are characteristic diagrams of the optical system used in the light beam scanning recording device according to the present invention, and FIGS. 7 and 8 are FIG. 3 is a configuration block diagram showing another embodiment of the output control circuit in the light beam scanning recording device according to the present invention. 10... Main body 12... Recording laser diode 14... Synchronization laser diode 16... Output control circuit 18... Drive circuit 22
... Resonance type optical deflector 24 ... fθ lens 30.
...Grid 36a, 36b...Photodetector 38...Image signal generation circuit 40...Frequency multiplication PLL circuit 42...Control information memory 44...D/A converter 46...Drive circuit 51... Output control circuit 52... Image signal generation circuit 54... Operational amplifier 5
6... Output control circuit 58... Image signal generation circuit 60... Digital arithmetic processing circuit 62... D/A converter L,... Recording laser beam L2... Synchronization laser beam F・・・Film FIG
, 6 Heel L diameter; Sole and Mu angle θ (storm) Incident angle to the deflection mirror surface φ (degrees) Loss rate (%)

Claims (6)

[Claims] (1) A light beam scanning recording device that scans a record carrier with a light beam to record character information, image information, etc., includes a scanning optical system that scans the light beam, and an image that generates an image signal corresponding to the image information, etc. a signal generation means, a control data storage means for storing control data for controlling the light quantity of the light beam according to the characteristics of the scanning optical system, and a light quantity adjustment for adjusting the light quantity of the light beam based on the image signal and the control data. A light beam scanning recording device comprising: means. (2) A light beam scanning recording device in the apparatus according to claim 1, wherein the scanning optical system includes a resonant optical deflector that deflects the light beam in the main scanning direction of the record carrier and an fθ lens. . (3) In the apparatus according to claim 1, the image signal generation means and the control data storage means supply the image signal and the control signal to the light amount adjustment means based on the synchronization signal from the synchronization signal generation means. Light beam scanning recording device. (4) A light beam scanning and recording device according to claim 1, wherein the light amount adjusting means comprises a drive circuit that drives a laser diode as a light source of the light beam. (5) When scanning a record carrier with a light beam to record character information, image information, etc., create control data to control the light intensity of the light beam according to the characteristics of the scanning optical system that scans the light beam, and then: A light beam control method, comprising adjusting the amount of light of the light beam based on an image signal corresponding to the image information and the like and the control data. (6) In the method according to claim 5, when the scanning position of the light beam with respect to the record carrier is y, the rate of change in the light beam transmission efficiency of the scanning optical system at the position y with respect to the center of scanning of the light beam. is Δη(y), the rate of change in spot diameter of the light beam is Δd(y), the rate of change in scanning speed of the light beam is Δv(y), and an arbitrary constant is k_1,
The rate of light intensity correction of the light beam ΔP(y) is ΔP(y)=k_1・[Δv(y)/{Δη(y)・Δ
d(y)}].