JPS63257714A - Light beam scanner - Google Patents

Abstract

PURPOSE:To obtain a beam scanner for generating easily an exact synchronizing signal without complicating a scanning optical system, by setting vertically the joint surface direction of a laser diode, in the grating arranging direction of a reference grating plate. CONSTITUTION:A laser light L1 of a recording diode 12 brings a film F to a main scan in the direction as indicated with an arrow A through a collimator 20, an oscillating deflector 22, and an ftheta lens 24. The laser light L2 of a synchronizing diode 14 passes through a collimator 28 and scans a reference grating plate 30 in the direction as indicated with the arrow A. Scanning lines 33, 31 are parallel and in an equal distance from the deflector 22. As for the plate 30, long-sized windows 32a are arranged at a prescribed interval vertically in the direction A, and a condensing rod 34 generates a clock signal by detectors 36a, 36b of both ends and controls a laser L1 driving circuit 16 through an output control circuit 17. The joint surface direction of the diode 14 is placed vertically in the grating 30 scanning direction A, a light spot 40a of the laser light L2 having a long axis orthogonal to the direction A is made and the window 32a is irradiated effectively, and a pulse light of a high S/N is sent to the detectors 36a, 36b, by which a synchronizing signal is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light beam scanning device, and more particularly, the present invention relates to a light beam scanning device, and more particularly, it scans a laser beam output from a laser diode along a reference grating plate through a scanning optical system. The present invention relates to a light beam scanning device that records or reads images based on a synchronization signal obtained by this method.

[Background of the invention] For example, in the fields of printing and plate making, rationalization of work processes,
2. Description of the Related Art Image scanning reading and recording systems that electrically process image information carried on a document to create a film original are widely used for the purpose of improving image quality.

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

Here, a synchronization signal is required in order to accurately read the image information carried on the document or to accurately record and reproduce the image information on the record carrier. Therefore, for example, in the image recording apparatus, a synchronization signal is generated by scanning a laser beam along a reference grating plate. In this case, a plurality of slits are arranged at predetermined intervals along the scanning direction on the reference grating plate, and the device generates a desired synchronization signal based on the pulsed light obtained from the laser light passing through the slits. There is.

Incidentally, the slit is usually formed by forming a transmission part on a glass plate or the like using vapor deposition technology, and if dust or the like adheres to the transmission part or if the transmittance is low, the transmission part is removed. The amount of laser light that passes through this will decrease. In this case, the S/N ratio of the pulsed light obtained from the laser light decreases, resulting in a drawback that it becomes difficult to generate an accurate synchronization signal. Note that if the synchronization signal is inaccurate, image information formed based on this synchronization signal will also be inaccurate, resulting in deterioration of image quality.

In order to increase the S/N ratio, the laser beam is shaped into an ellipse that corresponds to the shape of the transparent part using a cylindrical lens, etc., and the transparent part is effectively irradiated with this shaped laser beam. It is possible to configure However, in this case, relatively expensive parts such as a cylindrical lens are required as the scanning optical system, and the positioning of these parts also needs to be adjusted, which makes the entire device expensive and has the drawback of hindering mass production. will occur together.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned disadvantages, and the beam spot of the laser light irradiated onto the reference grating plate is directed in a direction perpendicular to the scanning direction of the reference grating plate. To provide a light beam scanning device that can easily and inexpensively generate an accurate synchronization signal without complicating a scanning optical system by setting the junction surface direction of the laser diode so that the laser diode has a long length. The purpose is to

[Means for Achieving the Object] In order to achieve the above object, the present invention uses a scanning optical system to direct laser light output from a laser diode against a reference grating plate in which gratings are arranged along the scanning direction. A light beam scanning device that obtains pulsed light by scanning the pulsed light and records or reads an image based on a synchronization signal generated from this pulsed light, and the laser diode has a junction surface that is aligned with the reference grating plate. The laser diode is characterized in that the laser diode is set perpendicular to the arrangement direction of the formed grating.

[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 main body of an image recording device which is a light beam scanning device according to the present invention. A synchronizing laser diode 14 that outputs laser light L2 is included. In this case, the recording laser diode 12 is drive-controlled by a drive circuit 16, and the synchronization laser diode 14 is drive-controlled by a drive circuit 18. Note that the drive circuit 16 for the recording laser diode 12 is controlled by an output control circuit 17 that outputs a control signal according to the image signal.

The laser light output from the recording laser diode 12 is made into a parallel beam by a collimator 20, and the film F sliding on the drum 26 is directed in the direction of arrow A through an optical deflector 22 that swings in the direction of the arrow and an fθ lens 24. main scan. In this case, the film F is held between the drum 26 and the pair of nip rollers 27a and 27b, and is conveyed in the sub-scanning direction in the direction of arrow B.

The synchronizing laser beam L2 output from the synchronizing laser diode 14 is made into a parallel beam by a collimator 28, and is main-scanned in the direction of arrow A on a grid 30 serving as a reference grating plate via an optical deflector 22 and an fθ lens 24. . In this case, the grid 30 is arranged so that the main scanning line 31 of the synchronizing laser beam and the main scanning line 33 of the recording laser beam on the film F are parallel to each other and are at equal distances from the optical deflector 22. Ru.

Here, as shown in FIG. 2, the grid 30 has a transparent part 32a and a non-transparent part 32b, which constitute a long slit in a direction perpendicular to the main scanning direction (arrow A direction), and a non-transparent part 32b at a predetermined interval. are formed alternately. Furthermore, this grid 3
A condensing rod 34 is disposed on the back surface of the camera 0, and photodetectors 36a and 36b are provided at both ends of the condensing rod 34.

The output signals from the photodetectors 36a and 36b are supplied to the output control circuit 17 as a clock signal.

On the other hand, the laser beams, L, output from the laser diodes 12 and 14 are diverging beams, and as shown in FIG. Form. In this case, the long direction (X-axis direction) of the beam 40 is perpendicular to the direction C of the junction plane between the P-type semiconductor and the N-type semiconductor that constitute the laser diodes 12 and 14.

Therefore, in FIG. 2, the synchronizing laser diode 14
is at a conjugate image position shown by the broken line with respect to the optical deflector 22, the synchronizing laser diode 14
The joint surface direction C is set to be orthogonal to the main scanning direction (direction of arrow A) in the grid 30.

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

The synchronizing laser diode 14 is driven under the action of the drive circuit 18, and the synchronizing laser light L2 is output. This synchronizing laser beam Lt is made into a parallel beam by the collimator 28 and then enters the optical deflector 22. The optical deflector 22 swings at high speed, and the synchronizing laser beam L2 reflected by the optical deflector 22 scans the grid 30 in the main scanning direction (six directions of arrows) via the fθ lens 24. In this case, the grid 30 has a transparent portion 32 along the main scanning direction.
a and non-transmissive portions 32b are alternately formed, and the synchronizing laser Lx that has passed through the transparent portion 32a enters the photodetectors 36a and 36b as pulsed light via the condensing rod 34.

Here, the synchronizing laser beam L2 incident on the fθ lens 24
and the beam diameter d on the focal plane of the fθ lens 24
That is, the wavelength of the laser beam L2 is λ, and the focal length of the fθ lens 24 is λ, and the beam diameter d of the synchronizing laser beam L2 that is irradiated onto the transmission part 32a on the grid 30 via the fθ lens 24 is When is f, there is a relationship as follows (K: constant of proportionality).

On the other hand, the synchronizing laser diode 14 moves in the main scanning direction of the grid 30 (in the direction of arrow A) at a position where its junction surface direction C is conjugate with respect to the optical deflector 22 (the position indicated by the broken line in FIG. 2). are arranged orthogonally.

Here, the optical deflector 22, which is an optical system, scans the cemented surface direction C.
When projected onto the grid 30 through the fθ lens 24, the direction is parallel to the main scanning direction. In this case, the long axis direction of the beam 40 in the synchronizing laser light L2 has a characteristic that it is orthogonal to the junction surface direction C of the synchronizing laser diode 14, as shown in FIG. Therefore, the transmission part 32 of the grid 30 is transmitted through the fθ lens 24.
The synchronizing laser beam L2 irradiated onto the point a forms a beam spot 40a having a long axis perpendicular to the main scanning direction of the grid 30 (direction of arrow A).

In other words, since the beam diameter before passing through the fθ lens 24 and the beam diameter d on the focal plane of the fθ lens 24 are inversely proportional to each other based on the relationship of equation (1), the synchronization laser light L2 is directed in the long axis direction of the beam 40. The short axis direction of the beam spot 40a is converted into the short axis direction of the beam spot 40a, and the short axis direction of the beam spot 40a is converted into the long axis direction of the beam spot 40a. Therefore, the laser beam L2 is extremely effectively irradiated onto the transmitting portion 32a, which is formed to be elongated in a direction perpendicular to the main scanning direction. As a result, even if there is dust or scratches on the transmission section 32a, most of the synchronization laser beam L2 reaches the converging rod 34 and the S/
The light enters the photodetectors 36a and 36b as pulsed light with a high N ratio.

The pulsed light incident on the photodetectors 36a, 36b is photoelectrically converted by these photodetectors 36a, 36b, and is supplied to the output control circuit 17 as a pulse signal. In the output control circuit 17, the pulse signal is multiplied to a predetermined frequency by a PLL circuit or the like to generate a synchronization signal. Therefore, the image signal corresponding to the image information drives the drive circuit 16 based on the synchronization signal. In this case, the synchronization signal is S/N
Since it is generated from a pulse signal with an extremely high ratio, the drive circuit 16 is controlled by reading the image signal accurately.

Therefore, the recording laser diode 12 outputs recording laser light by the driving action of the drive circuit 16 based on the control of the synchronization signal. 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 optical deflector 22. The recording laser beam reflected by the optical deflector 22 scans the film F in the main scanning direction (arrow A direction) via the fθ lens 24. On the other hand, the film F is being conveyed in the sub-scanning direction in the direction of arrow B while being held between the drum 26 and nip rollers 27a and 27b, and an image is two-dimensionally formed on the film F by the recording laser beam LI. That will happen.

In this case, the synchronization signal that contributes to the intensity modulation of the recording laser beam L+ is generated extremely accurately, as described above, so that an even and high-quality image is formed. Also,
Since the beam spot 40a of the synchronization laser beam Lx irradiated onto the grid 30 is set so that its long direction is perpendicular to the main scanning direction (six arrow directions) of the grid 30, the interval between adjacent transparent parts 32a is It becomes possible to arrange the two parts closer to each other. Therefore, by adjusting the interval between the transmitting parts 32a to correspond to the shape of the beam spot 40a and making them as close as possible, pulsed light with a higher frequency can be obtained from the grid 30.

Therefore, an accurate and high frequency synchronization signal can be easily generated using an inexpensive PLL circuit. As a result, it is also possible to record image information with higher density and accuracy.

Here, the synchronizing laser diode 14 and the collimator 28
If a slit member 42 having an opening 42a as shown in FIG. It becomes possible to generate pulsed light with improved N ratio.

That is, the length of the long axis of the beam spot 40a formed on the transmission section 32a of the grid 30 is inversely proportional to the width of the opening section 42a of the slit member 42 from the relationship of equation (1). Therefore, by setting the width of the aperture 42a small, the length of the long sleeve of the beam 40a increases, making it possible to obtain a pulse signal with an even higher S/N ratio.

[Effects of the Invention] As described above, according to the present invention, images, etc. In a light beam scanning device that performs recording or reading, the direction of the junction surface of the laser diode is set to be perpendicular to the direction in which the gratings formed on the reference grating plate are arranged. In this case, the laser light output from the laser diode diverges into an elliptical cone shape with a long sleeve perpendicular to the junction surface. Therefore, the beam spot of the synchronization laser beam irradiated onto the reference grating plate through the scanning optical system is set so that its long direction is perpendicular to the arrangement direction of the gratings formed on the reference grating plate. become. Therefore, since the synchronization laser beam is effectively irradiated to each grating that constitutes the reference grating plate, the S/N ratio will hardly decrease even if there are scratches or dust on the grating, for example. This allows extremely accurate pulsed light to be obtained. As a result, it is possible to generate an accurate synchronization signal from the pulsed light, and it is possible to obtain the effect that it is possible to read or record high-quality images, etc.

Further, since the long sleeve of the elliptical beam spot of the synchronizing laser beam is oriented in a direction perpendicular to the arrangement direction of the gratings constituting the reference grating plate, the grating interval can be further narrowed. . Therefore, the pulsed light can be easily made to have a high frequency, and it is possible to read or record more detailed images based on the high-frequency synchronization signal generated from the pulsed light. Note that the beam spot of the synchronizing laser beam can be easily set to a desired state with respect to the reference grating plate without using any shaping optical system, so a light beam scanning device with a simple and inexpensive configuration can be used. can be provided.

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 spirit of the invention.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the main body of a light beam scanning device according to the present invention, FIG. 2 is an explanatory diagram of the main part configuration of the light beam scanning device according to the present invention, and FIG. 3 is an output characteristic diagram of a laser diode. FIG. 4 is an explanatory diagram of another embodiment of the light beam scanning device according to the present invention. IO... Main unit 12... Recording laser diode 14... Synchronization laser diode 16... Drive circuit 17... Output control circuit 18... Drive circuit 22... Optical deflector 24
...fθ lens 30...grid 36a,
36b...Photodetector F...Film L,...Recording laser light L2...Synchronization laser light procedure correction! F
(Voluntary) Mourning July 16, 1986

Claims (2)

[Claims] (1) Pulsed light is obtained by scanning a reference grating plate with gratings arranged along the scanning direction using a scanning optical system with the laser light output from a laser diode, and the synchronization generated from this pulsed light A light beam scanning device that records or reads images based on signals, the laser diode being arranged such that the direction of the junction surface of the laser diode is perpendicular to the direction in which the gratings formed on the reference grating plate are arranged. A light beam scanning device characterized in that: (2) In the device according to claim 1, the laser light output from the laser diode is beam-shaped by a slit set narrowly in the direction of the junction surface of the laser diode, and the scanning optical system is A light beam scanning device configured to irradiate a reference grating plate through the light beam.