JPH0354545A - Optical recording device - Google Patents

Abstract

PURPOSE:To prevent the lifting of a film and to obtain a high-resolution image by press-bonding a plane glass on a photosensitive surface and performing exposure. CONSTITUTION:The film 7 on a moving state 8 is deflected by a rotary polygon mirror 4 and irradiated to be exposed with laser beam from a laser source 1 which passes an ftheta lens 5. The plane glass plate 6 is press-bonded on the photosensitive surface of the film 7 to prevent the lifting of the film 7. As a result, the high-resolution image without defocusing is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording device such as a laser beam printer.

[Prior Art] In optical recording devices that use a laser to write on photosensitive film, the photosensitive film generally lifts up, but in conventional optical recording devices, the depth of focus of the laser is a few millimeters. This was large, and the deviation due to film lifting was absorbed within this range, so it did not pose a particular problem.

[Problems to be Solved by the Invention] However, in recent years, optical recording devices with higher resolution have become desired, and the depth of focus has also become smaller as a result. In other words, the wavelength of the laser,
When the exit side F-number of the optical beam is F, the spot diameter of the 1/e'' value is φ, the depth of focus is Δχ, and k is a constant around 2, the following relationship holds approximately.

φ=k・λ・F (1) Δχ=±k・λ・F2 (2) Equations (1), (2
), when the spot diameter and depth of focus are calculated with k=2 and λ=0.78gm, the results are shown in Table 1.

According to Table 1, as the spot diameter becomes smaller, the depth of focus also becomes smaller rapidly.

In other words, in an optical recording device with a minute spot diameter, the amount of lifting of the photosensitive film is larger than the depth of focus, and as a result, the obtained image may be out of focus, which is not desirable.

Table 1 An object of the present invention is to provide an optical recording device that can prevent the above-mentioned lifting of a photosensitive film and provide high-resolution images.

[Means for Solving the Problems] The present invention, which can solve the above problems, is an optical recording device in which a laser beam emitted from a laser light source is deflected and scanned by a rotating polygon mirror to write an image on a photosensitive film. This is an optical recording device in which a flat glass plate is installed so as to be pressure-bonded and exposed to light, and the flat glass plate is coated with anti-reflection coating.

The present invention will be explained with reference to the drawings.

FIGS. 1 and 2 show the configuration of an apparatus according to an example of the present invention, and show aspects in the main scanning plane and the sub-scanning plane, respectively.

In Figures 1 and 2, 1 is a semiconductor laser, 2 is a collimator lens, 3 is a cylindrical lens having power in the sub-scanning direction, 4 is a rotating polygon mirror, and 5 is a spherical lens and a toric lens. An fθ lens, 6 a flat glass plate coated with antireflection coating, 7 a photosensitive film, and 8 a moving stage that moves in the sub-scanning direction.

First, the laser beam emitted from the semiconductor laser is converted into a parallel beam by the collimator lens 2, and then converged in the sub-scanning direction by the cylindrical lens 3, forming a line image near the mirror surface of the rotating polygon mirror 4. do. The laser beam reflected by the mirror surface of the rotating polygon mirror 4 is converged by the fθ lens 5,
The beam passes through a flat glass plate 6 and forms a beam spot on a photosensitive film 7 pressed onto the flat glass plate 6. The flat glass plate 6 and the photosensitive film 7 are placed on a moving stage 8, and are moved in the sub-scanning direction as the moving stage 8 moves.

As described above, by pressing the flat glass plate 6 onto the photosensitive film 7, warping or lifting of the film can be prevented, and an image with the entire screen in focus can be obtained even with an optical recording device with a minute spot diameter. ．． Further, by applying anti-reflection coating to the flat glass plate 6, the laser light reflected by the flat glass plate 6 does not flare and sensitize the photosensitive film, thereby preventing adverse effects such as reducing the contrast of the image.

As the flat glass plate, optical glass, blue plate glass, virex glass, etc. having a thickness of about several millimeters can be used.

In addition, anti-reflection coating applied on a flat glass plate includes a single layer film deposited with MgFz, MgF2, Sin
, AI203, CeF,, TiOz, Zr(h
, CeOz, and other dielectrics are deposited in appropriate combinations.

In addition, photosensitive films include wet silver salt films in which fine crystal grains of silver halide are dispersed in gelatin, and non-photosensitive organic silver salts such as silver halide, silver behenate, silver penzotriazole, etc. A dry silver salt film or the like containing a silver salt as a main component can be used.

[Example] The present invention will be specifically explained below using Examples.

Optical recording was performed using the apparatus shown in Figures 1 and 2.

A 20mW semiconductor laser is used as a laser light source, and F
Deflection and convergence were performed using a lens with a value of 15 to obtain a spot diameter of 23 μm.

The flat glass plate used was 5 mm thick and had an anti-reflection coating applied to the surface using a multilayer film. A dry silver halide film is used as the photosensitive film, and the speed is 8 mm/s in the sub-scanning direction.
Writing with a laser was performed while moving the moving stage at a speed of ec. The obtained image was a high-resolution image with no out-of-focus.

In place of the planar moving stage, a cylindrical rotating drum as shown in FIG. 3 was used, rotating at a circumferential speed of 8 n+m/sea.

In this embodiment, the flat glass plate 6 moves in parallel in the sub-scanning direction, and at the same time, the rotary drum 9 rotates to move the photosensitive film 7 in the sub-scanning direction. In this case, the photosensitive film 7 is pressed between the flat glass plate 6 and the rotating drum 9, and lifting of the photosensitive film on the scanning line is prevented, resulting in a good image.

The photosensitive film was moved using a conveyor belt as shown in FIG.

In the figure, the photosensitive film 7 is moved in the sub-scanning direction by moving the film conveying belt 11 in the sub-scanning direction due to the rotation of the rotating roller 10. As a flat glass plate, 22cm x 5cm x O. Images were written in the same manner as in Example 1 using a 5 cm piece of blue plate glass on which a multilayer film was deposited.

The obtained image was a good image with high resolution.

[Effects of the Invention] As explained above, by press-bonding a flat glass plate to a photosensitive film and exposing it to light, lifting of the film can be prevented and images with higher resolution can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of the apparatus of the present invention viewed from the main scanning direction, FIG. 2 is a schematic diagram of FIG. 1 viewed from the sub-scanning direction, and FIG.
FIG. 4 is a schematic view from the sub-scanning direction showing another example of the apparatus of the present invention. l... Semiconductor laser 2... Collimator lens 3.
...Cylindrical lens 4...Rotating polygon mirror 5...
・Fθ lens 6...Flat glass plate 7...Photosensitive film 8...Moving stage 9...Rotating drum
lO...Rotating roller l1...Film transport belt

Claims (1)

[Claims] 1. In an optical recording device that deflects and scans a laser beam emitted from a laser light source using a rotating polygon mirror and writes an image on a photosensitive film, a flat glass plate is installed so as to be pressed onto the photosensitive film, An optical recording device that performs exposure. 2. Device according to claim 1, characterized in that the flat glass plate is a glass plate with anti-reflection coating.