JPH0657044B2 - Light beam irradiation device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam for recording an image by scanning a recording medium with a light beam modulated by digital image information from the outside such as a computer and a facsimile. The present invention relates to an irradiation device.

2. Description of the Related Art In recent years, devices for recording image signals such as characters and figures from a computer or a facsimile by using a light beam such as a laser beam have been widely used in recent years.

Hereinafter, a conventional light beam irradiation apparatus will be described with reference to FIGS.
It will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a conventional light beam irradiation apparatus using a semiconductor laser. 1 is a semiconductor laser, 2 is a collimator lens, 3 is a polygon deflector, 4 is an imaging lens, 5 is a laser beam, and 6 is a laser beam. The photosensitive member 7 is a drive circuit, and the drive signal 8 output from the drive circuit 7 drives the semiconductor laser 1.

The semiconductor laser 1 is subjected to light intensity modulation according to an image by the drive circuit 7, the modulated laser light is collimated by the collimator lens 2, and the polygon deflector 3 deflects and scans the photoconductor 6. On the photoconductor 6, the laser beam 5 is focused by the imaging lens 4 to have an appropriate beam diameter. As shown in FIG. 2, the laser beam 5 scanned on the photoconductor 6 scans the deflection direction orthogonal to the rotation direction of the photoconductor 6 in the main scanning direction and as the photoconductor 6 rotates. This direction is called the sub-scanning direction. In FIG. 2, 9A, 9
B, 9C, 10A, 10B, 10C, 11A, 11B,
Reference numeral 11C is a digital pixel, and an image can be recorded by modulating the laser beam 5 and exposing the photoconductor 6 according to the digital pixel information in the main scanning direction and the digital pixel information in the sub-scanning direction. . In FIG. 2, the digital pixel 10B is the irradiation part of the laser beam 5. At this time, a method of making the exposed portion of the laser beam 5 visible is called a negative phenomenon, and a method of making the non-exposed portion visible is called a positive phenomenon.

FIG. 5 is a circuit block diagram of a light beam irradiation device in a conventional example, and reference numerals 15, 16 and 17 are shift registers for storing pixel information for one line in the main scanning direction including the light beam being irradiated. That is, the shift register 15 includes the digital pixels 9A, 9B, 9C, ... 9 in the main scanning direction shown in FIG.
The pixel information of N is stored, and similarly, the shift register 16 includes digital pixels 10A, 10B, 10C, ...
The shift register 17 stores the pixel information of 10N and the pixel information of the digital pixels 11A, 11B, 11C, ... Reference numeral 18 denotes a discriminating circuit for discriminating whether the pixel information of the pixel to be currently irradiated and the pixel information of a total of nine points adjacent or obliquely adjacent thereto is light irradiation information or non-irradiation information.

Next, the operation will be described. The image signal is stored in the shift register 16 that stores the pixel information of the main scanning line including the light beam being irradiated and the shift registers 15 to 17 that store the pixel information of the vertically adjacent main scanning lines. From these shift registers 15 to 17, it is possible to obtain a total of nine points of pixel information of the pixel being irradiated and the pixels adjacent thereto and diagonally adjacent thereto.
Put in. The discriminating circuit 18 discriminates whether the pixel information is light irradiation information or non-irradiation information, and outputs a control signal 19 for increasing the light beam spot diameter of the semiconductor laser. The semiconductor laser drive circuit 7 increases the light beam spot diameter of the semiconductor laser according to the light irradiation information 10B ′ of the pixel 10B currently being irradiated and the control signal 19 to expose the photoconductor.

FIG. 6 shows an example in which the light beam spot diameter is increased when the pixel information of a total of nine points of the pixel being irradiated and the pixels adjacent thereto or diagonally adjacent thereto is all light irradiation information. As another example, when the pixel information of the pixel being irradiated and at least the four pixels adjacent thereto are all light irradiation information, the light beam spot diameter may be increased. By making the irradiation spots 20 and 21 have large spot diameters in this way, pitch unevenness in the sub-scanning direction is corrected and black streaks in the non-image area in the case of positive development are eliminated. In addition, the pixels 9B, 9 adjacent to the non-irradiated portion
C, 9D, 9E, 10B, 10E, 11B, 11C, 1
Since the spot diameters of 1D and 11E are not increased, the defect that the image becomes thin as in the conventional case is also eliminated. As a result of the development experiment, it was found that the minute black stripes 22 for one pixel in the figure did not appear in the image.

A specific example of increasing the light beam spot diameter of the semiconductor laser will be described with reference to FIGS. 7 and 8. In FIG. 7, when the driving current of the semiconductor laser is increased from a to b, the light intensity of the laser light increases from a ₁ to b ₁ . In FIG. 8, since the light intensity distribution of the light beam spot on the photoconductor corresponding to the light intensity has a Gaussian shape like a ₂ and b ₂ , the threshold value of the amount of light visualized on the photoconductor is shown. Let Et be Et, the beam spot diameter is expanded from a ₃ to b ₃ for each light intensity. Therefore, the light beam spot diameter can be increased by increasing the driving current of the semiconductor laser.

FIG. 9 shows an example of a semiconductor laser drive circuit. This circuit increases the light beam spot diameter when the pixel information of four pixels adjacent to the light beam spot being irradiated is all light irradiation information. is there. Control signal 19 of discrimination circuit 18
As a result, a current flows through the transistor 23 and is added to the current of the laser driving transistor 24 to drive the semiconductor laser 1. As a result, the diameter of the light beam spot on the photoconductor can be increased.

However, this method has a drawback in that, at the intersection of black lines, the edge of the intersection is freckled or crushed due to the developing characteristics, and the sharpness of the intersection cannot be obtained.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a light beam irradiation apparatus which can obtain the sharpness or smoothness of the line at the intersection of the black line portions.

In order to achieve the above object, the light beam irradiation device of the present invention is a light source that emits a light beam that is modulated according to image information that is composed of digital pixels, and a recording medium that records the light beam from this light source. Scanning means for forming an image on and scanning, a storage means for storing at least a part of pixel information of a pixel adjacent to a light beam spot currently being irradiated and a pixel obliquely adjacent thereto, and each storage of the storage means. The information processing apparatus further includes a determination unit that determines whether the information is light irradiation information or non-light irradiation information, and a control unit that increases the diameter of the light beam spot that is currently being irradiated according to the result of the determination made by the determination unit. Of the pixel information of 8 points adjacent to and obliquely adjacent to the light beam spot, the light beam spot diameter is increased when the pixel information of at least 4 points adjacent to each other is unirradiated information. The edge of the intersecting portion of the image is sharpened or the diameter of the light beam spot is reduced to smooth the edge of the intersecting portion of the image.

Description of Embodiments An embodiment of the present invention will be described below with reference to the drawings.

FIG. 13 shows an embodiment of the present invention. In this embodiment, the irradiated light beam spot diameter is increased to sharpen the edges at the intersections of the images, or the light beam spot diameter is decreased. The edges of the intersections of the images are made smooth, and at least four points which are adjacent to each other continuously in the pixel information of eight points of pixels which are adjacent to and obliquely adjacent to the pixel 34 being illuminated [in the present embodiment, Pixels 35-3
When the pixel information [8] is non-irradiation information, the light beam spot diameter is changed. In the case of positive development, when the light beam spot diameter is increased to 34a, the intersection of images becomes sharp. If the light beam spot diameter is reduced to 34b, the intersection becomes smooth.

In the case of negative development, FIG. 10 shows an example of correcting the thinning of the black line 25a by lengthening the modulation time when the black line 25 becomes thinner than the white line adjacent in the main scanning direction, and FIG. 11 shows the black line. In the case where 26 is fuzzy, the modulation time is shortened to correct the fuzzy black line 26a. FIG. 12 is a circuit diagram and its signal waveforms diagram of a circuit for correcting the modulation time, signal 2 obtained by delaying the modulated drive signal 28 T _D time by the delay circuit 27
9 and the original drive signal 28 are passed through an AND circuit 30 or an OR circuit 31 to obtain signals 32 and 33, and the modulation time is expanded or compressed.

Although the semiconductor laser 1 is used as the light source in each of the above embodiments, any light beam using a CRT, LED array, or the like as the light source may be used.

EFFECTS OF THE INVENTION As described above, according to the present invention, the light beam spot diameter is increased by discriminating the pixel information adjacent or obliquely adjacent to the light beam spot currently being irradiated. Can be used to correct the sharpness and smoothness of the image at the intersection of the black lines to improve the image.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a conventional light beam irradiation device, FIG. 2 is an explanatory diagram of a scanning direction of a light beam, FIG. 3 is an explanatory diagram of image quality deterioration due to pitch unevenness in a sub scanning direction, and FIG. FIG. 5 is a circuit block diagram of a main part of a light beam irradiation device in a conventional example, FIG. 6 is an explanatory diagram of pitch unevenness correction by the light beam irradiation device, and FIG. FIG. 8 is an explanatory view of the relationship between the driving current of the semiconductor laser and the laser light intensity in the beam irradiation device, FIG. 8 is an explanatory view of the distribution of the light beam spot, and FIG. FIG. 10 is a diagram in which image thinning is corrected, FIG. 11 is a diagram in which image fringing is corrected, FIG. 12 is a circuit diagram of a modulation time correction circuit, and FIG. 13 is sharpness and smoothness at intersections of images. It is the figure which corrected. 1 ... Semiconductor laser, 3 ... Polygon deflector, 5 ... Laser beam, 7 ... Driving circuit, 15, 16, 17 ... Shift register, 18 ... Discrimination circuit, 27 ... Delay circuit, 30
... AND circuit, 31 ... OR circuit.

Claims (1)

[Claims] 1. A light source for emitting a light beam modulated according to image information composed of digital pixels, a scanning means for forming an image of the light beam from the light source on a recording medium and scanning the recording medium, and present irradiation. A storage unit that stores at least a part of pixel information of a pixel adjacent to a light beam spot inside and a pixel that is diagonally adjacent to each other, and determines whether each storage information of the storage unit is light irradiation information or non-light irradiation information. And a control unit that increases the diameter of the light beam spot currently being irradiated according to the determination result of the determination unit.
When the pixel information of at least four points that are adjacent to each other out of the pixel information of eight points that are adjacent to and obliquely adjacent to the light beam spot that is currently being irradiated is unirradiated information, the light beam spot diameter is increased and the image is increased. The light beam irradiation device is characterized in that the edge of the intersection is sharpened or the diameter of the light beam spot is reduced to make the edge of the image smooth.