JPH01177769A - Optical beam scanning device - Google Patents

Abstract

PURPOSE:To adjust the magnification of an image, etc., that is read or recorded by varying the wavelength of an optical beam to use the chromatic aberration and adjusting the scanning range of the optical beam. CONSTITUTION:The temperature (t) of a laser diode 23 constituting a laser emitting part 12 is detected by a temperature sensor, and compared with a prescribed temperature t0 by a comparator 25. The temperature t0 is a temperature to obtain the wavelength lambda of a laser beam L1 for synchronization necessary to scan on grid 36 in a desired scanning range. Then, corresponding to an output from the comparator 25, the temperature (t) of the diode 23 is adjusted to the prescribed temperature t0 by using a temperature adjuster 26 in order to obtain the laser beam L1 for synchronizing having the necessary wavelength lambda. Therefore, the laser beam L1 is adjusted of its scanning range by means of the chromatic aberration of a scanning lens 28, hence scans on the grid 36 in a desired scanning range. As a result, a synchronizing signal having a desired synchronization can be generated from a pulsative optical signal obtained from the laser beam L1 passing through a slit 34. Thus the magnification of an image on a film F can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light beam scanning device, and more particularly, a light beam is guided to a grid through a scanning optical system to generate a synchronization signal, and In an apparatus for reading or recording an image, etc. by guiding a light beam onto a scanned object via a scanning optical system based on the synchronization signal, the chromatic aberration of the scanning optical system is used by adjusting the wavelength of the light beam. The present invention relates to a light beam scanning device that can finely adjust the magnification of images, etc. to be read or recorded.

[Background of the Invention] For example, in the fields of printing and plate making, image information carried on a manuscript is electrically processed to streamline work processes and improve image quality.

Image scanning reading and reproducing systems for creating ilm master plates are widely used.

This image scanning, reading and reproducing system basically consists of an image reading section and an image recording section.

In the image reading section, the original document being conveyed in the sub-scanning direction is main-scanned by a photoelectric conversion element or a light beam, and image information carried on the original document is converted into an electrical signal. On the other hand, the image information photoelectrically converted in the image reading section is subjected to arithmetic processing such as gradation correction and edge enhancement according to the plate-making conditions in the image recording section, and then converted into an optical signal such as a laser beam, which is then used to film the film. Recording and reproduction are performed on a record carrier made of a photosensitive material such as.

Incidentally, in such an image scanning reading and reproducing system, a synchronization signal is required in order to accurately read image information from a document or to accurately record image information on a record carrier. Therefore, in the image recording section, a pulsed optical signal is obtained by guiding a synchronizing laser beam to the grid via a scanning optical system, and a synchronizing signal is generated based on this optical signal.

Then, the recording laser beam is controlled based on the synchronization signal to record and reproduce image information on the record carrier.

Here, in order to form an image with a desired magnification on the record carrier using the recording laser beam, the magnification of the scanning optical system, the position of the record carrier with respect to the scanning optical system, the position of the grid, etc. must be accurately set. It is necessary to keep it. However, it has been pointed out that it is technically extremely difficult to set these accurately, and that a considerably expensive adjustment device is required.

Therefore, as a method to adjust the magnification of the image at low cost, the interval of the synchronization signal obtained from the grid can be adjusted, for example.
There is a method of electrically correcting and adjusting the magnification of recorded and reproduced images by changing the multiplier of the PLL circuit. However, in this case, the multiplier of the PLL circuit can only be changed discretely. Therefore, it is extremely difficult to perform highly accurate magnification adjustment using an electrical method, and it is inappropriate for fields that require precise reproduction images, for example, fields that handle medical images.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and includes generating a synchronization signal by guiding a light beam to a grid through a scanning optical system, and directing the light beam to the synchronization signal. In a device that reads or records an image, etc., guided onto a scanned object through a scanning optical system based on the above, the scanning range of the light beam is adjusted by changing the wavelength of the light beam and using the chromatic aberration of the scanning optical system. It is an object of the present invention to provide a light beam scanning device that can extremely easily and accurately finely adjust the magnification of an image to be read or recorded.

[Means for Achieving the Object] In order to achieve the above object, the present invention provides a method for directing a light beam from a semiconductor laser to a grid based on a synchronization signal generated by guiding the light beam from a semiconductor laser to a grid through a scanning optical system. A light beam scanning device that reads or records an image or the like guided onto an object to be scanned includes a control means for controlling the wavelength of the light beam and a scanning optical system having chromatic aberration characteristics, and the wavelength is adjusted by the control means. The present invention is characterized in that the magnification of an image or the like is adjusted by guiding the light beam onto the grid and/or the object to be scanned through the scanning optical system.

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

In FIG. 1, reference numeral 10 indicates a light beam scanning device according to this embodiment, and this light beam scanning device 10 is an LD.
It includes a laser emitting section 12 that outputs a synchronizing laser beam L1 under the action of a driving section 11, and a laser emitting section 14 that outputs a recording laser beam L2 under the action of an LD driving section 13.

The synchronizing laser beam output from the laser emitting section 12 is guided to a galvanometer mirror 20 via a collimator 16 and a mirror 18. Further, the recording laser beam L2 outputted from the laser emitting section 14 is guided to the galvanometer mirror 20 through the collimator 22 and the mirror 18 in a state where it is deviated by an angle α with respect to the synchronizing laser beam.

Here, among the laser emitting sections 12 and 14, at least the laser emitting section 12 that outputs the synchronizing laser beam L1 is configured to include a temperature adjustment mechanism shown in FIG. 2. That is, the laser emitting unit 12 includes a laser diode 23 that outputs the synchronizing laser beam L+, a temperature sensor 24 that detects the temperature of the laser diode 23, and compares the temperature of the laser diode 23 detected by the temperature sensor 24 with a predetermined temperature. and a temperature regulator 26 that adjusts the laser diode 23 to the predetermined temperature based on the output signal from the comparator 25.

On the other hand, the galvanometer mirror 20 reflects and deflects the synchronizing laser beam L1 and the recording laser beam L2 by vibrating the mirror at high speed, and the laser beams L1 and L2 reflected and deflected by the galvanometer mirror 20 pass through the scanning lens. 28 to a synchronizing signal generating section 30 and an image recording section 32, respectively. In this case, an fθ lens having chromatic aberration is used as the scanning lens 28.

The synchronization signal generator 30 has a grid 36 in which a large number of slits 34 are arranged at equal intervals along the scanning direction of the synchronization laser beam L1, and the synchronization laser beam L1 is guided to the grid 36 via a mirror 38. It will be destroyed. In this case, a condensing rod (not shown) is arranged on the back side of the grid 36, and the synchronizing laser beam is guided to the photoelectric conversion element 40 via this condensing rod and converted into an electrical signal. be done.

The electrical signal is multiplied by a PLL multiplier circuit 42 and supplied to an output control section 44 as a synchronization signal. Note that the output control section 44 controls the LDD movement section 13 based on the image signal and the synchronization signal.

The image recording section 32 basically comprises a drum 46 that sub-scans and conveys a film F, which is a recording carrier, in the direction of the arrow, and nip rollers 48 a # and 48 b that are pressed against the drum 46 via the film F. In this case, the recording laser beam L2 guided to the image recording section 32 via the scanning lens 28 records an image by main scanning the film F in the direction of arrow B from between the nip rollers 48a and 48b.

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

First, the synchronizing laser beam L1 output from the laser diode 23 constituting the LD drive unit 11 and 12 is adjusted to a predetermined beam diameter by the collimator 16, and then enters the galvanometer mirror 20 via the mirror 18. Next, the synchronizing laser beam L1 reflected and deflected by the galvanometer mirror 20 vibrating at high speed enters the mirror 38 via the scanning lens 28, and is then reflected and guided to the grid 36 constituting the synchronizing signal generating section 30. . In this case, a large number of slits 34 are arranged in the grid 36 along the scanning direction, and the synchronizing laser beam L1 transmitted through the slits 34 is transmitted as a pulsed optical signal to a photoelectric conversion element via a condensing rod (not shown). Leading to 40. Therefore, the photoelectric conversion element 40 converts the optical signal into an electric signal and supplies it to the PLL multiplier circuit 42 to generate a synchronization signal. .

On the other hand, the output control section 44 sequentially processes the image signals based on the synchronization signal and outputs a control signal to the LDD movement section 13. In this case, the laser emitting section 14 is connected to the LDD moving section 13.
A recording laser beam L2 modulated according to the image signal is output under the action of the recording laser beam L2.

The recording laser beam L2 output from the laser emitting unit 14 is made into a parallel beam by the collimator 22, and then collimated by the mirror 1.
8 and enters the galvanometer mirror 20 while being deviated by an angle α with respect to the synchronizing laser beam L1. The galvanometer mirror 20 reflects and deflects the recording laser beam L2 and guides it to the image recording section 32 via the scanning lens 28.

In this case, the recording laser beam L2 is transmitted to the nip roller 48a,
48b, the film F is main scanned in the direction of arrow B.

On the other hand, the film F is conveyed in the sub-scanning direction by the drum 46 in the direction of arrow A, so that image information is two-dimensionally recorded and reproduced on its surface.

Here, if the position of the scanning surface of the grid 36 or the scanning surface of the film F is not set accurately in the light beam scanning device 10, it will not be possible to form an image of a desired size on the film F. This will cause inconvenience. That is, the synchronizing laser beam L+ is deflected by the galvanometer mirror 20 and scans on the grid 36, and the scanning range of the synchronizing laser beam L1 on the grid 36 is the distance between the galvanometer mirror 20 and the grid 36. Or it depends on the magnification of the scanning lens 28, etc. In this case, since the scanning speed of the synchronizing laser beam L1 depends on the scanning range, if this scanning range is inaccurate, the synchronizing signal generated by the synchronizing signal generator 30 including the PLL multiplier circuit 42 will also be inaccurate. , the magnification of the image formed based on this synchronization signal becomes inaccurate. Also, the recording laser beam L2 on the film F
If the scanning range of the image is inaccurate, the magnification of the image formed will also be inaccurate.

In this embodiment, the image magnification is adjusted using the chromatic aberration of the scanning lens 280 by adjusting the wavelength of the synchronization laser beam. In this case, there is a relationship shown in FIG. 3 between the temperature t of the laser diode 23 (see FIG. 2) and the wavelength λ of the synchronizing laser beam L1 output from the laser diode 23. That is, the higher the temperature, the longer the wavelength. On the other hand, in this embodiment, an fθ lens having chromatic aberration is used as the scanning lens 28, and the ratio (ΔY/ Y
) There is a relationship shown in Figure 4. Incidentally, the scanning position variation ΔY is caused by a change in the refractive index due to the wavelength λ of the synchronizing laser beam, and is defined with respect to the scanning position Y as shown in FIG. Therefore, by adjusting the temperature t of the laser diode 23 from the relationships shown in FIGS. 3 and 4, the scanning range of the synchronizing laser beam L1 on the grid 36 can be adjusted.

Therefore, in FIG. 2, a temperature sensor 24 detects the temperature t of the laser diode 23, and a comparator 25 compares a predetermined temperature t0 with the temperature t. In this case, the predetermined temperature 1. is the temperature at which the wavelength λ of the synchronizing laser beam L1 necessary for scanning the grid 36 in a desired scanning range is obtained, and is determined from the relationship shown in FIGS. 3 and 4. Next, the temperature t of the laser diode 23 is set to a predetermined temperature t using the temperature regulator 26 according to the output of the comparator 25. By adjusting the wavelength λ, it is possible to obtain a synchronizing laser beam having a desired wavelength λ. Therefore, the synchronizing laser beam L1 is transmitted to the scanning lens 2.
The scanning range is adjusted by the chromatic aberration of 8, and the grid 36
The upper surface is scanned over a desired scanning range, that is, at a desired scanning speed. As a result, it is possible to generate a synchronization signal with a desired interval from the pulsed optical signal obtained from the synchronization laser beam L+ that has passed through the slit 34, so that the synchronization signal is recorded on the film F based on the synchronization signal. The magnification of the image will also be adjusted accurately.

In the embodiment described above, the wavelength λ is changed by adjusting the temperature t of the laser diode 23, but this wavelength λ depends on the optical output P from the laser diode 23, as shown in FIG. It also changes depending on. Therefore, the LD driving section 11 and the laser emitting section 12 are configured to include a light output adjustment mechanism shown in FIG. The laser diode 23 outputs a synchronizing laser beam based on the drive current from the current control circuit 50. The optical output P of this synchronizing laser beam L1 is detected by a photodiode 52 and fed back to the current control circuit 50 via a current amplifier circuit 54. In this case, the current control circuit 50 controls the laser diode 23 so that the wavelength λ of the synchronizing laser beam becomes a desired wavelength λ set based on the relationship shown in FIG. 4 based on the optical output P detected by the photodiode 52. control. As a result, as in the case described above, a synchronization signal having a predetermined interval is generated from the synchronization signal generating section 30, and an image with an accurate magnification is formed on the film F based on this synchronization signal. It turns out.

Here, the wavelength of the recording laser beam L2 can be adjusted by adjusting the temperature or the optical output of the laser emitting section 14, and the magnification of the image recorded on the film F can also be adjusted. In this case, if the respective laser emitting units 12 and 14 are controlled so that the wavelengths of the synchronizing laser beam L1 and the recording laser beam L2 change in opposite directions, the magnification fluctuation of the image recorded on the film F will increase. Therefore, it is possible to adjust the magnification of images over a wide range.

[Effects of the Invention] As described above, according to the present invention, a synchronization signal is generated by guiding a light beam from a semiconductor laser onto a grid via a scanning optical system, and the light beam is generated based on the synchronization signal. In a device that reads or records an image or the like guided onto a scanned object through a scanning optical system, the wavelength of the light beam is adjusted and the scanning range of the light beam is adjusted using the chromatic aberration characteristics of the scanning optical system. It is configured like this. In this case, the wavelength of the light beam output from the semiconductor laser can be changed simply by controlling the temperature or optical output of the semiconductor laser. Therefore, the scanning range of the light beam that scans the grid or the object to be scanned can be adjusted very easily and accurately, thereby finely adjusting the reading or recording magnification of images, etc. for the object to be scanned. becomes possible.

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 invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a light beam scanning device according to the present invention, FIG. 2 is a block diagram of the main part configuration of a light beam scanning device according to the present invention, and FIGS. 3 and 4 are a schematic diagram of a light beam scanning device according to the present invention. FIG. 5 is an explanatory diagram of the characteristics of the semiconductor laser used in the scanning device. FIG. 5 is an explanatory diagram of the scanning optical system in the optical beam scanning device according to the present invention. FIG. Characteristic Explanation Diagram FIG. 7 is a block diagram showing the main part configuration of another embodiment of the light beam scanning device according to the present invention. 10... Light beam scanning device 12.14... Laser emitting unit 20... Galvanometer mirror 23... Laser diode 24... Temperature sensor 2
5... Comparator 26... Temperature regulator 28
...Scanning lens 30...Synchronization signal generator 3
2... Image recording section 36... Grid 50.
...Current control circuit 52...Photodiode 5
4...Current amplification circuit F...Film L1...
・Laser beam for synchronization L2... Laser beam for recording procedure correction form (voluntary) October 14, 1988 Mi'Fl? ! ! ffl bottle (
1. Indication of the incident Patent Application No. 1848 of 1988 2)
Title of the invention Light beam scanning device 3, relationship with the case of the person making the amendment Patent applicant 4, agent 6, subject of the amendment (1) “Detailed description of the invention” in the specification
Column 7, Contents of amendment (1) The amendment will be made as stated in the attached sheet. 1. In the "Detailed Description of the Invention" in the specification, the phrase "medical images, etc." on page 4, line 20 will be amended to read "printing/plate-making, etc." 2) On page 11, line 16, the phrase "is also inaccurate" should be corrected to "the period of is also inaccurate." 3. Correct the word "interval" in line 17 of page 13 to read "period." 4. The word "interval" in lines 18 and 19 of page 14 will be corrected to "period."

Claims (3)

[Claims] (1) A light beam scanning device that guides a light beam from a semiconductor laser onto a scanned object based on a synchronization signal generated by guiding a light beam to a grid through a scanning optical system to read or record images, etc. comprising a control means for controlling the wavelength of the light beam and a scanning optical system having chromatic aberration characteristics, the light beam whose wavelength has been adjusted by the control means is transmitted to the grid and/or the object to be scanned through the scanning optical system. A light beam scanning device characterized by adjusting the magnification of an image, etc. by guiding the light beam upward. (2) A light beam scanning device according to claim 1, wherein the control means is a temperature adjustment mechanism that sets the semiconductor laser to a predetermined temperature. (3) A light beam scanning device according to claim 1, wherein the control means comprises a light output adjustment mechanism that sets the light output of the semiconductor laser to a predetermined output.