JPS61262365A - Light beam irradiating device - Google Patents

Abstract

PURPOSE:To record a picture with excellent resolution by providing a memory storing the density level of picture elements adjacent to picture element region while being irradiated at present, a means for changing the time width of an irradiation pulse of a light beam proportional to the density level and a means for changing the start time of an irradiation pulse of a light beam. CONSTITUTION:A picture signal read by an image sensor enters a shift memory 6 while the density level of each picture element is digitized. A semiconductor laser 1 is modulated by a pulse width proportional to the density level of the shift memory 6 to be irradiated and irradiated on a photosensitive body 4. On the other hand, the density level of the picture element adjacent to the picture element being irradiated at present in the shift memory 6 is discriminated by a comparison circuit 7, and the start time of a drive pulse to the said semiconductor laser 1 is controlled by a control circuit 9 so that a laser beam spot is in contact with the picture element having a larger density level and the semiconductor laser 1 is driven by a signal from a pulse width modulation circuit 8. The laser light of the semiconductor laser 1 subjected to pulse width modulation scans on the photosensitive body 4 by a polygon deflector 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light beam irradiation device that records an image by scanning a light beam modulated by a digital image signal onto a photoreceptor.

BACKGROUND OF THE INVENTION In recent years, light beam irradiation devices have been used in lasers, printers, etc. that modulate a light beam using digital image signals from an image sensor reader, etc., and scan and record an image on a photoreceptor. There is.

An example of the conventional light beam irradiation device mentioned above will be described below with reference to the drawings.

FIG. 6 shows a schematic configuration diagram of a conventional light beam irradiation device. In FIG. 6, 21 is a semiconductor laser, 22
is a polygon deflector, 23 is an imaging lens, 24 is a photoreceptor,
37 is a semiconductor laser drive circuit. Further, 31 is a document, 32 is an illumination light source for the document 31, 33 is a focusing fiber array, 34 is an image sensor, and 36 is a reading circuit, which constitutes an image document reading device.

The operation of the conventional light beam irradiation device configured as described above will be described below. The image signal from the device composed of the image sensor 34 and the like is transmitted to the white area. Or a comparison circuit 36 that determines the black part.
is converted into a white or black digital pixel signal. The light intensity of the semiconductor laser 2 is modulated by the drive circuit 37 based on this pixel signal. The modulated laser beam of the semiconductor laser 21 is scanned onto a photoreceptor 24 by a polygon deflector 22. The imaging lens 23 is a lens that focuses the laser beam onto the photoreceptor 24 to a specified beam diameter. Digital pixel signals are recorded on the photoreceptor 24 through the operations described above.

Problems to be Solved by the Invention However, in the above-described configuration, the resolution of the recorded image is determined by the pixel density of the image sensor 34, and especially at the boundary where the black and white image changes within one pixel of the image sensor 34. If the image spans an area, it is rounded to white or black, so if an image read by a reading device is recorded by a light beam irradiation device, the resolution will be poor.

Resolution deterioration will be explained with reference to FIGS. 7 and 8. 7th
In the figure, when the boundary area between the black part (image part) and the white part of J draft A is read with one pixel a of the image sensor, the reading circuit 35
The read output B becomes an output b below the determination level. Then, when the comparison circuit 36 determines black and white, the laser drive signal C
In this case, it is determined that the image is white and no signal is output, and the entire one pixel C of the recorded image D becomes white. Therefore, the original black part is approximately 1 pixel
Since /3 (the illustrated pixel) is white, a white concave portion is formed.

Conversely, when one pixel a reads the black and white boundary area of the document A in the state shown in FIG. 8, the reading output B of the reading circuit 36 is an output b that is higher than the determination level.

Therefore, the comparator circuit determines that it is black, and the laser drive signal C is output. Therefore, in the recorded image D, the entire one pixel c1 becomes black, and a convex portion is formed in the original black portion.

If digitization is repeated in such a state, there is a problem in that the recorded characters, lines, etc. become uneven and jagged images.

In view of the above-mentioned problems, the present invention provides a light beam irradiation device that can record images with good resolution when a document such as a character image is read and recorded by an image sensor or the like.

Means for Solving the Problems In order to solve the above problems, the light beam irradiation device of the present invention includes a memory that stores the density level of the pixel adjacent to the pixel area currently being irradiated, and a memory proportional to the density level. The apparatus includes means for changing the time width of the irradiation pulse of the light beam, and means for comparing and determining the density levels of the adjacent pixels and changing the start time of the irradiation pulse of the light beam.

According to the above-described structure, the present invention changes the irradiation time of the light beam in accordance with the density level of the pixel, and also directs the light beam so that it comes into contact with the adjacent pixel with a higher density level depending on the state of the density level of the adjacent pixel. By irradiating the beam, the boundaries of black and white images can be predicted and good recorded images with high resolution can be obtained.

EXAMPLE Hereinafter, a light beam irradiation device according to an example of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a light beam irradiation device in an embodiment of the present invention. In FIG. 1, 1 is a semiconductor laser, 2 is a polygon deflector, 3 is an imaging lens, 4 is a photoreceptor, 6 is a shift memory that stores the pixel density level, 7 is a density level comparison circuit, and 8 is a density level A modulation circuit generates a laser drive pulse with a proportional pulse width, 9 is a circuit that controls the start time of the pulse, and 10 is a semiconductor laser drive circuit.

The operation of the light beam irradiation device configured as above will be explained below with reference to FIG. 1.

The image signal read by the image sensor digitizes the density level of each pixel and enters the shift memory 6. The semiconductor laser 1 is modulated with a pulse width proportional to the density level to be irradiated by the shift memory 6, and is irradiated onto the photoreceptor 4. On the other hand, the comparison circuit 7 determines the density level of the pixel adjacent to the pixel currently being irradiated in the shift memory 6, and the laser beam spot is set so that the laser beam spot contacts the pixel with the higher density level.
A control circuit 9 controls the start time of a driving pulse for the semiconductor laser 1, and the semiconductor laser 1 is driven by a signal from a pulse width modulation circuit 8.

A pulse width modulated laser beam from a semiconductor laser 1 is scanned over a photoreceptor 4 by a polygon deflector 2 . Reference numeral 3 denotes an imaging lens that focuses the laser beam onto the photoreceptor 4 to a prescribed spot diameter. The shape of the laser beam spot imaged on the photoreceptor 4 has a short width in the scanning direction and a long shape 6 in the orthogonal direction so that pulse width modulation is effective for recording images.

FIG. 2 shows an example of a specific circuit configuration of the light beam irradiation device of the present invention. In fig.

6 is a shift register for storing the digitized image density level; 17 is a digital comparator for determining the density level; 18 is a density level counter; 19 is a pulse start counter; 20 is a semiconductor laser drive circuit; 16 is 1
It is a clock oscillator with the frequency necessary to subdivide the pixel by density level.

The operation of the light beam irradiation device configured as described above will be explained below. In FIG. 2, image density signal n1
enters shift register 6. The shift register 6 is an N-bit shift memory necessary to store the density level of each pixel. The digital comparator 17 compares the adjacent pixel density levels "d-1+" and "nd+1" of the pixel currently being irradiated, and sets a counter value in the pulse start counter 9 under the following conditions.

0 when “d-1>”dol “m −”d” when d-1=”d+”
When d+, -(n--"d), where - is the maximum density level.

On the other hand, the density level counter 8 is set with the density level nd of the pixel to be currently irradiated. Clock oscillator 1
6, the pulse start counter 19 operates and a drive pulse start signal is applied, and the concentration level counter 18 operates through the gate circuit 14 to drive the drive circuit 20 with a pulse width.

3 and 4 are diagrams for explaining the state of the laser drive pulse in FIG. 2, and are diagrams showing recorded images at this time. FIGS. 3 and 4 show the case where the direction in which the black and white of the original changes is reversed. In FIGS. 3 and 4, if the density level of the shift register 16 after reading the original A (p is the pixel to be read) is B, the laser drive pulse is C, and so on.
It is driven so as to be in contact with the pixel with the higher density level among the adjacent pixels, and with a pulse width proportional to the density level.

The recorded image in this case is the third diagram. In general character images, there is a high probability that the boundary area between black and white is in contact with the image density side, so the image sensor A good recorded image with improved resolution rather than pixel density can be obtained. As shown in Figure 5A, if the density levels of adjacent pixels are the same, the read output will be as shown in Figure 5B, and in this case, the light beam spot will be at the center of the pixel as shown in Figure 5B. The laser drive signal (C in the same figure) is controlled as shown in FIG.

In the above embodiments, a case has been described in which a portion irradiated with a light beam is visualized, but a similar method can be used in the case of positive development in which a portion not irradiated with a light beam is visualized.

Effects of the Invention As described above, the present invention includes a memory for storing the density level of a pixel adjacent to a pixel currently being irradiated, a means for changing the irradiation pulse width of a light beam proportional to the density level, and a means for changing the irradiation pulse width of a light beam proportional to the density level, and a method for changing the density level of the adjacent pixel. By providing means for comparing and determining the light beam irradiation pulse start time, the resolution at the boundary between black and white, such as character images, can be sufficiently improved compared to the pixel density of image sensors, etc., and recording with good resolution can be achieved. You can get the image.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a light beam irradiation device according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an embodiment of a specific circuit of the light beam irradiation device of the present invention, FIG. 4 and 6 are diagrams showing the state of the laser drive pulse of the light beam irradiation device of the present invention and the recorded image at this time, FIG. 6 is a schematic configuration diagram of the conventional light beam irradiation device, and FIG. FIG. 8 is a diagram showing the state of a laser drive signal of a conventional light beam irradiation device and the recorded image at this time. 1.21... Semiconductor laser, 2.22...
...Polygon deflector, 3,23...Imaging lens, 4.24...Photoreceptor, 6...Shift memory, 7...Density level Comparison circuit, 8...
. . . Pulse width modulation circuit, 9 . . . Pulse start control circuit, 10 . . . Semiconductor laser drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
... 41 hands - 4... Gekkorin 5... Lede: Beam, Zunosetato 2 - Left, 7 fingers 2nd figure? O/7 nd-1< ndO-%nm
-nd Figure 3 3I-Sae, Hanawa 3? ...It's just a joke, 33,... Sesolef Musu 2. L>S' 34...Image゛, Senna I Fan 7

Claims (2)

[Claims] (1) A memory for storing at least density information of pixels adjacent to the pixel area currently being irradiated with the light beam, and means for changing the duration of the irradiation pulse of the light beam in proportion to the density level of the pixel currently being irradiated with the light beam. , a light beam irradiation device comprising means for comparing and determining the levels of density information of the adjacent pixels, and means for changing the irradiation pulse start time of the light beam being irradiated depending on the content of the comparison and determination means. . (2) The means for changing the irradiation pulse start time is configured such that the light beam spot being irradiated contacts a pixel region having a higher density information level of a pixel adjacent to the pixel region currently being irradiated with the light beam, and at least the density information Claim 1, characterized in that when the levels are equal, the irradiation pulse start time of the light beam being irradiated is controlled so that the center of the light beam spot being irradiated coincides with the center of the pixel. The light beam irradiation device described.