JPS5913733B2 - Optical writing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical writing method for electrophotographic recording, which allows recording of solid black and halftones.

FIG. 1 is a block diagram showing the principle of electrophotographic recording method. In this figure, a photoreceptor drum 1 is uniformly charged with corona by a charger 2, and an electrostatic latent image is formed on the photoreceptor drum 1 by selectively irradiating light with an optical writing system 3. This is reversely developed by a developing device 4, the toner image is transferred onto a sheet of paper 5 by a transfer device 6, and a permanent image is made by a fixing device T. On the other hand, the entire surface of the photosensitive drum 1 is irradiated with light by the erasing lamp 8 and the cleaner 9 returns it to its original state. FIG. 2a is an enlarged schematic diagram of an optical writing system 3 using a conventional LED light emitting element.

In this figure, reference numeral 10 indicates light emitting parts of LEDs, which are arranged at periodic intervals l. Of course, the length of the light emitting section 10 is smaller than this periodic interval l. 1.1 is a light source array.

The light emitted from the light emitting parts 1 and 0 travels in the direction of the arrow and forms a focusing optical fiber bundle (e.g. self-fock lens array: trade name).
12 and forms a light image 13 on one surface of the photoreceptor drum. Conventionally, the light emitting unit 10 and the convergent optical fiber bundle 12 are arranged so as to stand upright at the same magnification. If the distance between the light emitting unit 10 and the convergent optical fiber bundle 12 is X, then the distance between the convergent optical fiber bundle 12 and the photoreceptor drum 1 is also x. FIG. 2 shows the optical image 13 on the photosensitive surface of the photosensitive drum 1 viewed from above. As can be seen from this figure, since the optical image 13 is the image of the light emitting part 10 itself, the adjacent images 13 and 13 are separated by a periodic interval of l.
and the size of the light emitting section 10 and the difference therebetween. Therefore, in the recording by this optical writing system 3, the lines are not connected,
The print quality was poor, and it was impossible to record solid black.
FIG. 4a shows the intensity distribution on the imaging plane.

In this case, even if the light intensity of the light emitting element is changed, the light intensity distribution hardly changes.
It was impossible to change the area of the upper light irradiation part. Therefore, it has not been possible to record halftones by changing the luminous intensity and changing the diameter of the dots in the portion corresponding to the light emitting element. This invention was made in order to eliminate the above-mentioned drawbacks, and by changing the luminous intensity, it is necessary to create an electrostatic latent image on the surface of the photoreceptor with an electrostatic latent image of a size higher than the developable threshold of the image of one luminescent part. So that the diameter of the light intensity distribution can be changed,
The light source array and self-occurring lens array are shifted from the imaging position with respect to the photosensitive surface. The present invention will be explained in detail below with reference to the drawings. FIGS. 3 a to 3 d are enlarged schematic diagrams of an optical writing system showing an embodiment of the present invention. In the conventional example,
As shown in FIG. 2, with respect to the distance x between the light emitting unit 10 and the focusing optical fiber bundle 12, the distance between the focusing optical fiber bundle 12 and the photosensitive drum 1 is equal to X. As shown in FIG. 3A, the distance between the focusing optical fiber bundle 12 and the photosensitive drum 1 is set to y, which is longer than the distance X. In other words, it is a de-focus state. At this time, the spread of the light intensity distribution expands as shown in Figure 4b, so the light intensity (indicated by c in the figure) required to create an electrostatic latent image above the developable threshold is large. (effective diameter of image)
It is possible to change the By controlling the emission intensity, when the diameter of the image 13/ is equal to the periodic interval 1 of the light emitting section 10 as shown in FIG. 3c, a completely connected line can be drawn. On the other hand, when every other dot is irradiated with light, the limit diameter at which the dots between the unirradiated areas are resolved is 21, as shown in FIG. 3d. Therefore, the light intensity is Ic (fourth
If the luminous intensity is controlled so that the diameter of the portion shown in Figure b) is within the range of 1 to 21, the straight portions are connected and high quality printing with guaranteed resolution can be obtained. As explained above, the present invention has advantages such as being able to perform halftone recording and continuous line recording because the effective diameter of the image can be controlled by the emission intensity.

Furthermore, this effective diameter is set to 1 to 2 of the periodic interval 1 of the light emitting element.
Controlling within twice the range has the advantage of guaranteeing resolution.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle of electrophotographic recording, FIG. 2 is an enlarged schematic diagram of a conventional optical writing system, and FIG. 3 is an enlarged schematic diagram of an optical writing system showing an embodiment of the present invention. FIG. 4 is a light intensity distribution diagram on the surface of the photoreceptor.

Claims (1)

[Claims] 1. Optical writing for electrophotographic recording in which a photoreceptor is irradiated with light to form a latent image using a light source array consisting of a plurality of light emitting elements lined up at regular intervals and a focusing optical fiber bundle capable of forming an erect, equal-sized image. In the system, the light source array and the convergent optical fiber bundle are arranged with respect to the photosensitive surface of the photosensitive member so as to be shifted from the image forming position, and the image of one light emitting part is formed on the photosensitive surface at a level exceeding a developable threshold value. An optical writing method characterized in that the light emission intensity is controlled so that the diameter of the light intensity distribution of the light emitting elements necessary to create an electrostatic latent image is within a range of 1 to 2 times the arrangement interval of the light emitting elements. .