JPH0244429B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Subject of the Invention) The present invention is directed to recording an image such as a wiring pattern on an image recording material such as a printed circuit board coated with a photosensitive material film or the like based on an image signal input. Without,
The present invention relates to an image recording method that enables recording.

(Prior art) Two-dimensional image data is stored in a memory device or the like as a digital image signal, and the data is read out and a predetermined image pattern is applied to an image recording material using a swept light controlled by this image signal. The method for forming the above is described in Japanese Patent Application No. 58-47890 dated March 24, 1988 by the applicant of the present application.
It is disclosed in the specification of No.

In this method, even when scanning a non-image area, the image recording material is always made to reach a minimum amount of light that is not substantially exposed to the image recording material, and a part of the image recording swept light itself is branched, and the branched light is detects a position that exactly corresponds to the sweep position on the image recording material,
Based on the detected position signal, a feedback signal is generated to control the optical modulation timing.

However, in order to separate a part of the swept light using a half mirror etc. and obtain a position detection signal of the swept light,
A photodetector with the same sensitivity is used for swept light both when only an amount of light reaches the material surface that does not substantially sensitize the image recording material, and when recording the image area. Therefore, the difference in the sweep light level between the time corresponding to a non-image area with a small amount of light and the time corresponding to an image area with a large amount of light is too large, making detection processing difficult.

(Objective and Summary of the Invention) The present invention aims to eliminate the drawbacks of the prior art described above, and its gist is to record a predetermined image by optically scanning the recording surface of an image recording material. In doing so, the amount of light on the recording surface is such that at least the amount of light that does not substantially expose the photosensitive material is always present, and a part of the light sweeping on the recording surface is separated by a half mirror or the like, and the light sweep position is adjusted. In an image recording method in which light is modulated with an image signal whose timing is based on the position signal of the swept light input to the detection means and detected, the level of the position signal obtained by the optical sweep position detection means is , the strength of the sweep light is changed depending on the presence or absence of an image signal for controlling the sweep light, so that the level of the position signal when scanning a non-image area and the level of the position signal when scanning an image area are made almost the same. This is an image recording method.

(Example) Hereinafter, an example of image recording by the method of the present invention will be described with reference to the drawings.

Two-dimensional image data is stored in the recording device 1, converted into a time-series scanning signal for scanning by the CPU 2, and supplied to the AO (acousto-optic) light modulation amount 3.

The light beam emitted from the exposure beam light source, for example, the argon ion laser tube 4, is A
- A laser beam with an intensity that exposes the image recording material in the O light modulator 3, and an amount of light that does not substantially expose the image recording material (meaning the amount of light that reaches the surface of the recording material after being reflected by the half mirror 12, which will be described later). The laser light is modulated into two values, passes through an expander 5, passes through fixed mirrors 6 and 7, and enters a polygon mirror (multifaceted reflecting mirror) 8.

The polygon mirror 8 is rotated by a motor 9. The exposure beam reflected by each mirror surface is swung at a predetermined spread angle in a direction perpendicular to the plane of the paper.

Furthermore, the exposure beam is directed to a converging lens 1 placed very close to the polygon mirror 8.
0 and a fixed half mirror 12 disposed close to the printed circuit board 11, the light spot is swept and irradiated onto the unexposed printed circuit board 11.

The printed circuit board 11 is fixed to a stage 13, and the stage 13 is moved at a constant speed in the sub-scanning direction (in the direction of arrow O in the figure) by a motor 14.

Therefore, when the polygon mirror 8 rotates and the stage 13 moves, the entire surface of the printed circuit board 11 is sequentially scanned in a plane by the imaged light spot of the exposure beam.

On the other hand, the light transmitted through the half mirror 12 reaches the optical sweep position detection means A comprising a grating scale 15 and a photodetector 16, the details of which are shown in FIG.

This lattice scale 15 corresponds to the half mirror 12.
In contrast, it is placed at a position conjugate with the exposure position of the printed circuit board 11.

A part of the swept light to the printed circuit board 11 passes through the half mirror 12 and sweeps the lattice-like scale 15, so that the lattice of the scale 15 alternately repeats transmission and blocking, and the light is transmitted to the photodetector 16. incident on .

Therefore, in the photodetector 16, the laser light transmitted through the grating scale 15 is converted into a pulse signal, and the pulse signal as position information indicating the exposure position of the swept light on the printed circuit board 11 is converted to an amplification factor. It is amplified by a variable amplifier 17 and fed back to the CPU 2.

The amplifier 17 has 2 read out from the CPU 2.
A value image signal is input as a control signal,
Depending on the presence or absence of the image signal level, the amplification factor of the amplifier 17 is switched to increase the output signal to a predetermined signal level.

Therefore, among the laser beams that pass through the grating scale 15, the amplification factor of the corresponding pulse signal is increased for the non-image area where the amount of light is small.
By improving the S/N ratio of the position information fed back to the CPU 2, timing control in the CPU 2 can be performed reliably.

Furthermore, in the portion corresponding to the image portion, the amplification factor of the pulse signal is lowered so that the pulse signals in both the image and non-image portions are approximately at the same level.

That is, a pulse signal that is cut at an appropriate threshold level using a known technique and fed back as a rectangular wave is converted into a high frequency pulse by a PLL circuit, etc., and the pulse count information is converted into a high frequency pulse.
Based on the input to the CPU 2, the signal reading speed from the storage device 1 storing the original image is controlled, and light modulation can be performed in correct synchronization with the rotational speed of the polygon mirror 8.

In the above explanation, the swept light of the non-image area and the swept light of the image area become a swept position signal on the photodetector 16 via the half mirror 12 and the grating scale 15, and the amplification factor of the signal is The image section and the image section are different. However, in some cases, it may be better to attenuate the sweep position detection signal from the sweep light of the image area.

In addition, this amplification factor can be changed by changing the ratio of the amplifier's feedback resistor and input resistor using an analog switch, or by preparing two types of amplifiers or attenuators and converting the output of each into an analog There is a method of switching with SW etc. and using it as a sweep position detection signal.

In this way, the image read from the storage device 1 is correctly converted into a time-series scanning signal, and an undistorted image is stored on the printed circuit board 11.

In the above embodiments, the case of exposure to a printed circuit board has been described, but it goes without saying that the present invention can also be applied to other image recording materials (for example, photographic film, heat-sensitive materials for infrared laser exposure, etc.).

(Effects of the Invention) According to the present invention, it is possible to extract approximately the same position signal when scanning both the image area and the non-image area. , can be recorded.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a direct exposure apparatus for implementing the method of the present invention, and FIG. 2 is a front view showing an example of a grid-like scale. 1...Storage device, 2...CPU, 3...A-O
Optical modulator, 4... Argon ion laser tube, 5... Expander, 6, 7... Fixed mirror, 8... Polygon mirror, 9... Motor, 10
...Focusing lens, 11...Printed circuit board, 12...
... Half mirror, 13 ... Stage, 14 ... Motor, 15 ... Grid scale, 16 ... Photodetector, 17 ... Amplifier.

Claims (1)

[Claims] 1. When recording a predetermined image by optically scanning the recording surface of an image recording material, the amount of light on the recording surface is
The amount of light that does not substantially sensitize the photosensitive material is always present at the minimum, and a part of the light sweeping on the recording surface is separated by a half mirror, etc., and inputted to the light sweep position detection means, and the detected swept light is In the image recording method, the light is modulated with an image signal whose timing is based on a position signal, wherein the level of the position signal obtained by the light sweep position detection means is controlled by the image signal which controls the intensity of the sweep light. 1. An image recording method characterized in that the level of a position signal when scanning a non-image area and the level of a position signal when scanning an image area are made almost the same by changing the level of the position signal depending on the presence or absence of the image area.