JP3272109B2 - Gradation image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradation image recording apparatus for reproducing a gradation of an image by an area gradation method.

[0002]

2. Description of the Related Art For reproducing a gradation image, for example, an area gradation method for changing a ratio of a binary state of a gradation in an image is known. There are various area gradation methods. For example, there is a method in which one pixel is further divided into a plurality of unit pixels, and the gradation of one pixel is reproduced based on the shading ratio of each unit pixel. In this case, when reproducing multiple gradations, it can be dealt with by increasing the number of divisions of one pixel.

For example, a scanning optical printer as a means for reproducing a gradation image includes a printer head having an optical shutter in which a plurality of windows are arranged in a main scanning direction. The printer head and the photoconductor are relatively moved, and the amount of light irradiated on the photoconductor is controlled by selectively opening and closing windows according to the gradation of an image. As a result, an optical signal corresponding to a unit pixel is cumulatively exposed in the sub-scanning direction of the photoconductor, and a gradation image is reproduced.

In such an optical printer, when trying to reproduce the gradation of one pixel by changing the number of pixels of each unit pixel, it is necessary to increase the number of windows of the optical shutter in accordance with the divided unit pixels. it can.

[0005]

In order to reproduce a multi-tone image in the above-mentioned scanning printer, the number of windows of the optical shutter must be increased, and the structure of the optical shutter is miniaturized. Further, since the image of one pixel is reproduced by accumulating the unit pixels, the accumulation frequency increases with the reproduction of the multi-tone image. For this reason, in a scanning printer, it takes a considerable amount of time to obtain an image of one pixel.

Further, depending on the method of selecting the unit pixel,
Because the continuity of the image is lost or the center of gravity of the image is biased,
The gradation reproducibility of the image may be poor. Accordingly, the present invention has been made in view of the above circumstances, and has as its object to provide a gradation image recording apparatus capable of faithfully reproducing a multi-gradation image with a high-speed and simple-structure head. Fixed.

[0007]

A gradation image recording apparatus according to the present invention is a gradation image recording apparatus for optically recording a gradation image on a photosensitive recording medium by an area gradation method. A first recording unit that supplies a first recording energy having a level lower than a threshold value to the photosensitive recording medium; and an energy level of at least a part of the area where the first recording energy is accumulated. position as exceeds the threshold value, and a second recording means for supplying a second recording energy having a level below the threshold value, the first recording hand
The recording by the second recording means is performed on the recording area by the step.
By relatively moving the recording region, the level of the recording energy stored in the photosensitive recording medium is changed to change the area of the exposure region that exceeds the threshold, thereby reproducing a gradation image. The first recording unit and the second recording unit have an outer edge that can gradually change the area of the exposure region along a scanning direction that is a direction of relative movement with the photosensitive recording body according to the gradation. The recording is performed in the recording shape. The outer edge may be a hypotenuse or a curve. The first recording means and the second recording means each include an optical shutter provided between a light source and the photosensitive recording medium for controlling an exposure amount on the photosensitive recording medium, A first optical shutter of the recording unit and a second optical shutter of the second recording unit are arranged in the relative movement direction, and the pair of the first and second optical shutters is orthogonal to the relative movement direction. Are arranged in a plurality of directions.

[0008]

According to the means of the present invention, when a gradation image is to be reproduced by optical recording on a photosensitive recording medium by an area gradation method , the same area of the photosensitive recording medium is multiplex-recorded to reproduce the image. Is formed. That is, first, provisional recording is performed by the first recording unit, and then,
Complete recording is performed by the second recording means. The first recording means supplies a recording energy of a level lower than a threshold value which determines an image forming boundary of the sensitivity of the photosensitive recording medium . Further, the second recording means supplies a recording energy of a level lower than the threshold to the area recorded by the first recording means.

[0009] The recording energy level of the area recorded by both the first and second recording means exceeds the threshold value,
As a result, the area reaches the image forming area. Therefore, by varying the area of the region, that is, the image formation area, the gradation is reproduced based on the area gradation method. The recording energy supplied to the recording medium includes light, heat, and electric charge.
A photosensitive recording material, a heat-sensitive recording material, an electrostatic recording material, and the like react with each energy.

[0010] The first and second recording means are arranged so that the above-mentioned area is insensitive.
Exposure along the scanning direction, which is the direction of movement relative to the optical recording medium
An outer edge that can gradually change the area of the region according to the gradation
The outer edge of such a recorded shape is a hypotenuse
Or a curve. And such a record type
Multiplex recording by combining recording means
Thus, the gradation is reproduced linearly. Also, the first recording hand
A step and the second recording means, wherein a light source, the photosensitive recording medium,
And controls the amount of exposure to the photosensitive recording medium.
An optical shutter for each of the first recording means;
Optical shutter and second optical shutter of the second recording means
Are arranged in the relative movement direction, and the first and the
A pair of two optical shutters in a direction orthogonal to the relative movement direction.
The timing of each shutter opening and closing
By controlling the moving speed of the recording medium, the first shutter and the second
Gradation image by multiple exposure in combination with shutter
Is reproduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the principle of the present invention. FIG.
The ordinate and abscissa indicate the density D and the exposure amount E, respectively, showing the sensitivity characteristics of the recording medium. For example, an optical printer shows the sensitivity characteristics of a photosensitive recording medium. When the exposure amount exceeds a threshold value Eth, the density exceeds the threshold value Dth, thereby completely exposing the photosensitive element. A predetermined area of the photosensitive recording medium is exposed by opening and closing control of a window of an optical shutter.

For the photosensitive recording medium having the illustrated characteristics, the first exposure is completed when the first shutter 101 is opened. Since the first exposure is performed with light having a level smaller than the threshold value Eth, the density does not exceed the threshold value Dth in this state. Accordingly, a temporary exposure area a is formed on the photosensitive recording medium. Next, the region temporarily exposed by the first shutter 101 is moved to the second state by opening the second shutter 103.
Is completed. As described above, in the first exposure, the exposure amount of the photosensitive recording medium does not exceed the threshold value Eth. However, when the second exposure is completed, an area a ′ to be newly provisionally exposed is formed, and the exposure amount is further added to the area a. Therefore, the exposure amount accumulated on the photosensitive recording medium is reduced to the threshold Eth. Beyond. Therefore, the density of the photosensitive recording medium exceeds the threshold value Dth, whereby a completely exposed area b is formed on the photosensitive recording medium to form an image.

FIG. 2 shows an optical shutter. The optical shutter 201 includes a first shutter 101 having a triangular window.
And a second shutter 103 having a rectangular window are arranged in the scanning direction (the direction of the arrow in the figure), and a pair of shutters composed of the first shutter 101 and the second shutter are arranged in the scanning direction. They are arranged in orthogonal directions. Above the optical shutter 201, a UV light source (not shown) is disposed in the longitudinal direction, and the light from the light source is applied to a photosensitive recording body 203 that can be exposed to UV light through a window of each shutter.

Hereinafter, the exposure procedure will be described. First, the first shutter 101 is opened, the second shutter 103 is closed, and light from a light source is irradiated on the photosensitive surface of the photosensitive recording medium 203. Thus, the first exposure is completed. Next,
The first shutter 101 is closed, and the second shutter 1 is closed.
03 is opened, and the light of the light source is irradiated on the photosensitive surface of the photosensitive recording medium 203. Since the photosensitive recording medium 203 is moving in the direction of the arrow, the area temporarily exposed by the first exposure is
Complete exposure is performed by the second exposure.

The opening / closing timing of each shutter and the moving speed of the photosensitive member are synchronously controlled.
It is controlled so that complete exposure is completed in seconds. FIG. 3 shows an exposure pattern at each gradation. For example, an image of each gradation having eight gradations is obtained by multiple exposure using a combination of the first shutter 101 and the second shutter 103 having the window shape shown in FIG.

To reproduce eight frequency gradations, the exposure area is divided into seven equal parts by the operation of the first shutter 101, and is equally divided according to the gradation of the image which changes between one gradation and seven gradations. The exposed areas are completely exposed. This situation is shown in FIG. Further, as shown in FIG. 3B, the complete exposure area is accumulated according to the image that changes between the 1st gradation and the 7th gradation. In this case, the second shutter 103 is opened with respect to the provisionally exposed area, and the area is relatively moved by the required frequency.

Further, as shown in FIG.
The exposure patterns shown in (a) may be appropriately combined to obtain the required number of gradations. In this case, the second shutter 103 moves relative to the provisionally exposed area by the required frequency in a state where opening and closing are selectively repeated. Further, the exposure pattern shown in FIG.
It is also possible to combine the exposure pattern shown in FIG.

Various shapes and arrangement patterns of the windows of each shutter can be considered in addition to the above. For example, as shown in FIG. 4A, a first shutter 401 having a rhombic window and a rectangular window are provided. 4B, and a first shutter 40 having a window in which one side of a rectangle is combined with the base of a triangle as shown in FIG. 4B.
In some cases, a corresponding exposure pattern (black area in the figure) is obtained by combining the shutter pattern 5 with a second shutter 407 having a rectangular window.

Further, as shown in FIG. 4C, only a shutter 409 having a rectangular window is used, and the window of the shutter is opened and closed in accordance with the movement of the photoreceptor. As a result, double exposure is performed. Complete exposure may be obtained. Further, as shown in FIG. 4D, the first shutter 411 and the second shutter 413 having the shape shown in FIG.
Further, the third shutter 415 may be combined to obtain a complete exposure by triple exposure. In the case of triple exposure, preliminary exposure is completed by preceding double exposure, and third exposure is completed to obtain complete exposure.

As described above, there are various shapes of the window of the shutter. Thereby, the gradation can be reproduced linearly. In the above embodiment, the case of photosensitive recording is described. However, in the case of thermal recording, the heating time and the number of times of heating are controlled. Complete printing can be obtained.

[0021]

According to the invention described above , when a gradation image is reproduced by optically recording on a photosensitive recording medium by the area gradation method, each gradation depends on the size of a continuously changing image forming area. Will be reproduced. Therefore, it is possible to linearly reproduce multiple gradations as compared with the case where gradation is reproduced by a set of dots as in the related art.

A continuously changing image forming area is formed by overlapping a plurality of recording means. Therefore, unlike a conventional dot, there is no need for a recording means for recording a minute area, and there is no need for a number of recording means corresponding to multiple gradations. To high gradations can be reproduced. Further, even in the case of reproducing multiple gradations, the number of recording means is at least two, so that it is possible to easily control and record in a short time.

[Brief description of the drawings]

FIG. 1 is a principle diagram for explaining the present invention.

FIG. 2 is a diagram illustrating an optical shutter.

FIG. 3 is a diagram showing an exposure pattern at each gradation.

FIG. 4 is a diagram showing a window shape of an optical shutter.

[Explanation of symbols]

 101, 103, 401 to 415 Shutter 201 Optical shutter 203 Photosensitive recording medium

Claims (4)

(57) [Claims] 1. A gradation image recording apparatus for optically recording a gradation image on a photosensitive recording material by an area gradation method, wherein a first level having a level lower than a threshold value of sensitivity of the photosensitive recording material is provided.
First recording means for supplying the recording energy to the photosensitive recording medium; and for an area where the first recording energy is accumulated, at least a part of the energy level of the area exceeds the threshold. A second recording unit that supplies a second recording energy having a level lower than the threshold value, wherein the second recording unit supplies a second recording energy to the recording area of the first recording unit.
The recording area by the recording means is relatively moved to change the area of the exposure area where the level of the recording energy stored in the photosensitive recording medium exceeds the threshold value, thereby reproducing a gradation image. Image recording apparatus. 2. The image forming apparatus according to claim 1, wherein the first recording unit and the second recording unit gradually change the area of the exposure region along a scanning direction that is a relative movement direction with respect to the photosensitive recording medium according to the gradation. 2. The gradation image recording apparatus according to claim 1, wherein recording is performed in a recording shape having an outer edge that can be made. 3. The gradation image recording apparatus according to claim 2, wherein the outer edge is formed of a hypotenuse or a curve. 4. The recording apparatus according to claim 1, wherein the first recording unit and the second recording unit each include an optical shutter provided between a light source and the photosensitive recording body to control an exposure amount on the photosensitive recording body. The first optical shutter of the first recording unit and the second optical shutter of the second recording unit are arranged in the relative movement direction, and the pair of the first and second optical shutters is moved in the relative movement direction. 4. A gradation image recording apparatus according to claim 1, wherein a plurality of the gradation image recording apparatuses are arranged in a direction orthogonal to the direction.