JPH011367A - Scanning and recording method for binarized images - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a method for exposing and recording a binary image such as a line drawing on a photosensitive material such as a film by scanning a light beam, and in particular, it relates to a method for exposing and recording a binary image such as a line drawing on a photosensitive material such as a film by scanning a light beam. Concerning how to record accurately.

<Prior Art> FIG. 8 shows an outline of an example of a scanning and recording device for scanning and recording a binary image using a multi-beam that uses a commonly used laser beam.

That is, a laser beam l generated from a laser light source 21 is divided by a plurality of beam subrifters 22, and each divided beam is transmitted through an acousto-optic modulator (rAOMJ).
) 23, ON10FF is controlled by the corresponding binary image signal.

Among these beams, the beam for exposure is focused by a condensing lens 24, and is focused on a photosensitive material such as a film (hereinafter simply referred to as "film") wound on a cylinder 25.
26. The cylinder 25 is rotated in the X direction (referred to as the main scanning direction) in the figure and simultaneously driven in the Y direction (referred to as the sub-scanning direction), so that a required binarized image is scanned and recorded on the film 26.

Incidentally, important factors when recording such a binary image are the smoothness of image edges and their dimensional accuracy, which are particularly problematic in printed circuit patterns and the like.

For this reason, in the past, the beam diameter for one pixel was made larger than the corresponding pixel area, and the edges of both images were smoothed by exposing adjacent exposure areas in the main and sub-scanning directions to overlap considerably. method has been adopted.

<Problems to be Solved by the Invention> Figure 9 is a diagram when this overlapping exposure method is adopted in conventional multi-beam scanning exposure, and schematically shows the cross section of the luminous flux distribution of each beam in the sub-scanning direction. This is what I did.

In the figure, each beam has a Gaussian distribution expressed as W, ~ w1 as is well known, and the light amount distribution of the entire beam is expressed as W.

Therefore, due to variations in sensitivity of the film, the exposure darkness value for blackening the film 26 used is e! relative to this light amount distribution W as shown in FIG. 9.
It can be seen that the recorded line width varies as da, d+, and dz due to the difference in o, el□ e. This variation sometimes reaches as much as one pixel area, and is particularly problematic in printed circuit patterns that require precision.

Therefore, conventionally, exposure is performed by adjusting the amount of laser light to obtain the required image line width, but when the image contains both positive and negative images, such as the circuit pattern of a printed circuit board, , it is difficult to adjust the stroke width appropriately for both images.

The present invention aims to solve these problems by stably controlling the line width and reproducing it with high accuracy.

〈Means for solving problems〉 The present invention solves this problem in the following way.

That is, in the scanning recording method of a binarized image according to the present invention, a light beam corresponding to a pixel on a one-to-one basis is turned on according to the magnitude of a pixel signal. In this way, in the method of scanning and recording a binary image on a photosensitive material, exposure is performed such that the exposure area of the light beam corresponding to each pixel overlaps with the adjacent pixel.

Then, the dot data for each pixel is transmitted to the light beam ON1.
When converting to output dot data for 0FF control, the dot data for each pixel, the dot data for either the previous or subsequent pixel adjacent to it in the main scanning direction, and these two dot data are dot data of either two pixels adjacent to the front or rear in the sub-scanning direction, for a total of four pixels (hereinafter referred to as "adjacent four").
For the dot data of pixel J), (a) the logical product of the dot data of four adjacent pixels is "l"
When , the dot data of the pixel to be converted is converted to output dot data for turning on the light beam, and when the logical product is "0", the dot data of the pixel to be converted is converted to output dot data for turning off the light beam. Convert to output dot data, or (bJ OR of the dot data of adjacent 4i!Ii elements or convert the dot data of the pixel to be converted to output dot data for turning on the light beam when the value is 1°. However, when the logical sum is "O", the dot data of the pixel to be converted is converted into output dot data for turning off the light beam.

<Effect> The effects of the configuration of the present invention are as follows.

For each pixel, ON/OFF control of exposure is performed by the above-mentioned AND or OR in units of four adjacent pixel areas. Therefore, the exposure area of each pixel is determined by the logical operation of the data of a total of four adjacent pixels, since the scanning of the previous adjacent pixels in the main and sub-scanning directions (total of 3 times) is performed first.
, 2, 3. There are four stages of overlapping exposure.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing an outline of an optical system of an embodiment to which the present invention is applied, and FIG. 4 is a diagram showing the configuration of an image signal processing circuit that performs arithmetic processing on dot data.

A laser beam L0 from a laser light source (not shown) is split into two by a beam splitter 15, and a straight beam L,
is diffused in one direction by the rod lens 1, and the cylindrical lens 2 converts the diffused beam into parallel light.

At the aperture 3, the parallel light beams become parallel beams LA consisting of LA1 to I and □ whose light intensity distribution within each beam and between the beams is approximately -like. In addition, after the beam L2 is also reflected by the reflecting mirror 16, the optical system of the rod lens l', the cylindrical lens 2', and the aperture 3' generates a parallel beam L consisting of Ls+~L, , like the beam L1.
becomes.

The parallel beams LA, L, enter AOM 4.4' where ON/OFF control Il is applied to each beam as described below.
be done. Assuming that each of the parallel beams La and Lm due to the ON signal is the required exposure beam (the beam due to the OFF signal may be used as the exposure beam), they are directed in a fixed direction with respect to AOM4.4' as shown in the figure. L AIZLAN'...L All' and L□ +
The light is arranged and focused as a light spot Lst'...LI1, 1'.

All of these light spots are approximately twice as large in the main and sub-scanning directions as the exposure area corresponding to the pixel. Also, the exposure area array for the pixel of light point L% and the exposure area array for the pixel of light point Lll' are shifted by 1 pixel in the sub-scanning direction, and LA' and F are shifted by 4 pixels in the main scanning direction. ing.

This is because when the laser beams are so-called coherent lights of the same wavelength, if the beams overlap at the same time, interference will occur between them, causing defects recorded in the form of streaks. Therefore, in applications where the influence of this interference is not a problem, there is no problem in bringing the two light spot arrays closer together or in a single array.

Note that although the light spots in L, ' and L' are adjacent to each other in the sub-scanning direction, they are actually spaced apart to an extent that no interference occurs. In addition, recently a technology has been established to prevent this interference from occurring, and in this case, there is no need for the above-mentioned separation, and L.

' and L! Scanning in a state where l' overlaps is also possible.

The light spots formed by this LA'*LB' array scan in the right direction (main scanning direction) of the figure while blinking according to the dot data of each pixel, and at the same time the film is fed upward in the figure, and the required images are sequentially displayed. Exposure is recorded.

FIG. 3 is a schematic diagram showing the light amount distribution of the parallel beam LA (or LM) corresponding to FIG. 9.

When all of the beams divided as described above are viewed as ON signals, they have an overall flat light intensity distribution as shown by W1 to W7 in FIG. 3.

Next, FIG. 4 shows an example of an image signal processing circuit that generates ON/OFF control signals for each of the beams LA and Lll.

Creation of a binary image signal for each pixel in a series for scanning and recording has already been done in various scanners (laser bronters, etc.), so we will omit it here;
First, the controller 5 and the address counter 6 sequentially store each l line in the line memory 7a as an image signal array in the sub-scanning direction.

7b.

Next, the 2×2 mask calculation unit 8 performs a required logical operation as described later using the adjacent 4 pixel data read out by the data selector 9 for each pixel, and returns the result to 1
Dot data memo for each line 'J10a (or 10b)
) is stored in memory.

The dot data memory 10a is used to store dot data in the parallel beam LA shown in FIG. 2, and the dot data memory 10a is used to store dot data in the parallel beam Ls. It is controlled by.

In this way, during reading and arithmetic processing from the line memories 7a and 7b, data for the next line is transferred to the line memory 7C.
are written to line memories 7b and 7c after arithmetic processing.
A repeating process is performed in which data for the next line is written to the line memory 7a, and data for the next line is similarly read out and subjected to arithmetic processing.

The data in the dot data memory tab is read out to the AOM4', and the data in the dot data memo 'J10a is read out to the AOM4 by the delay circuit 11 as data delayed by 4 pixels from the dot data memo 1 month ob. Each laser beam split through AOM4.4' is polarized and modulated, and ON10 F F onto the film.
Next, the operation of controlling the image width by the 2×2 mask calculation unit 8 will be described.

Now, the position coordinates of pixels on l line (sub-scanning direction) consisting of n pixels are 1, 2, 3, etc. . . , i, . . . n, and the same <1.2, 3 . ..., j.

. . . n, and the pixel at the i-th and j-th intersection is represented by D l j.

The beam corresponding to pixel DIJ is pixel D +i+11j+
D i +J+H+ D +t*+l fj. 1. The area including the area (the area of four adjacent pixels) is to be exposed, and this is determined by a logical formula that is selected and set in advance before the work.

In other words, the exposure range is the logical product, Dij'Dfi・Ilj'Dben(...嘗)D(Todoroki・1
) (-・1) or logical sum, D,, +D, east side 1 j + D i (j+I
l + D (i ・1) (−・1) is
When it is "0", it is in an exposed state, and when it is "0", it is in a non-exposed state.

For the purpose of explanation, the width in the sub-scanning direction for one scanning exposure line in the main-scanning direction is assumed to be 8 dots, and the pattern P surrounded by a large frame is scanned and recorded as a desired image. In the schematic diagram, the binarized dot data in pattern P is "1" and the others are 0'.

In this embodiment, as mentioned earlier, the light spot for exposure is approximately twice the pixel width, so if pixel j is within the image area, the previous D +r-n (;-n +Di
Since the pixel fJ-11 and Dtt-nJ can also be exposed during scanning exposure, a total of four exposures can be obtained at most.

FIG. 5(A) shows the case using logical sum, and FIG. 6(A) shows the case using logical product. The numerical value in each pixel represents the number of times of overlapping exposure as a result of scanning exposure.

In addition, FIG. 5(B) shows the exposure amount (or number of exposures) for each pixel between E and E in FIG. 5(A) as a graph, and
Figure (B) is a graph representing the exposure amount (or number of exposures) for each pixel between F and F in Figure (A).

Also, Figure 7 is for comparison with Figures 5 and 6.
It is a schematic diagram when the data of each pixel is exposed as it is without performing the above-mentioned logical operation.

As is clear from the figure, in FIG. 5(B), when the exposure darkness value of the film is between the number of exposures of 3 and 4, the resulting blackened image area matches the desired image area, but 3 It will be seen below that the resulting image area is larger than the required image area, and that if it is larger than 4, no image will be recorded.

Similarly, in Fig. 6 (B), if the exposure darkness value is greater than 0 and less than 1, the blackened image width will be the required 4 pixels, but if it is greater than ■ and less than 2, it will be 3 pixels; It can be seen that if the number is 3 or less, one pixel is recorded, and if it is larger than 3, no image is recorded.

On the other hand, as is clear from Fig. 7, if scanning exposure is performed repeatedly without performing any logical operations, the desired pattern will be produced regardless of the exposure darkness value of the film at any level of the number of exposures. It can be seen that the same image as P cannot be recorded.

Therefore, for example, when the film sensitivity is low and the exposure darkness value is relatively high with respect to the beam star (for example, between the number of exposures 3 and 4 in FIG. 5(A)),
By setting the value to a logical sum, and the opposite case to a logical product, adjustment can be made so that an image of the required size is always obtained.

In this example, in order to make the image edges smoother, the light intensity inside each divided beam was changed to - by the aperture 3, so the image size was determined by the balance between the number of exposures and the exposure darkness value. As mentioned above, it has the advantage of being particularly easy to control digitally, but image dimensions can be similarly controlled even when applied to the conventional split beam with a Gaussian distribution.

Further, even if an image pattern includes both negative and positive images, exposure recording can be performed more accurately in accordance with the pixel signals.

Note that in FIG. 2, the amount of deviation in the sub-scanning direction between the divided parallel beams L and L is one pixel, but this does not necessarily have to be accurate.

Further, although the four adjacent pixels are assumed to be adjacent to the rear side in each of the main scanning direction and the sub-scanning direction, they may be adjacent to the front side. In addition, MultiBee 1 not only has exposure but also
Even in the IH combination of single beam exposure, exactly the same effect can be obtained by the present invention as long as the scanning exposure method in which the exposure areas overlap is used.

<Effects of the Invention> According to the present invention, since it works as described above, even if there are variations in sensitivity of photosensitive materials, by setting the 2×2 mask operation to logical sum or logical product accordingly, , image dimensions can always be recorded with high precision. Furthermore, even if negatives and positives are mixed, highly accurate recording is possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of an optical system according to an embodiment of the present invention;
Figure 2 is a diagram showing the arrangement of exposure beams, Figure 3 is a diagram of the light intensity distribution of the beam, Figure 4 is a bronch diagram of the image signal processing circuit,
FIGS. 5 and 6 are diagrams showing the state of logical operations for pattern P. In addition, for comparison with Figures 5 and 6, Part 7 is a schematic diagram of the case where the data of each pixel is exposed as it is without performing logical operations, and Figure 8 is an example of the conventional multi-beam exposure method. FIG. 9 is a diagram showing the beam light amount distribution in FIG. 8. ■, 1'...Rod lens 2.2'...Cylindrical lens 3.3'...Aperture 4.4'...AOM 5...Controller 6...Address counter 7a, 7b, 7c ...Line memory (1st to 3rd)
8...2x2 mask calculation unit 9...Data selector 10a, 10b...Don't data memory (1st to 3rd) 11...Delay circuit 15...Beam splitter 16...Reflection mirror Applicant Dainippon Screen Mfg. Co., Ltd. Agent Patent Attorney Tsutomu Sugitani Figure 1 Figure 2 Drawing system Figure 7 Figure 7 - Dimensions of N -

Claims (1)

[Claims] (1) In a method of scanning and recording a binary image on a photosensitive material by controlling ON/OFF of a light beam that corresponds one-to-one to a pixel according to the size of a pixel signal, dot data for each pixel is When converting into output dot data for light beam ON/OFF control, the dot data for each pixel, the dot data of either the previous or subsequent pixel adjacent to it in the main scanning direction, and these two For a total of four pixels of dot data, including dot data of two pixels adjacent to the dot data in the front or rear direction in the sub-scanning direction, the logical product of these four dot data is "1". When the dot data of the pixel to be converted is converted to output dot data for turning on the light beam, and when the logical product is "0", the dot data of the pixel to be converted is converted to the output dot data for turning on the light beam.
Convert to output dot data for FF, or when the logical sum of the four dot data is “1”, turn on the dot data of the pixel to be converted to the light beam.
Convert to output dot data for
0'', the dot data of the pixel to be converted is converted into output dot data for turning off the light beam, and the exposure area of the light beam corresponding to each pixel exposes the exposure area corresponding to the four adjacent pixels. A method for scanning and recording binarized images, characterized by: