JPH0638515B2 - Electrophotographic recording device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus for outputting and recording information including halftone.

2. Description of the Related Art Conventionally, as a method of recording a halftone with an apparatus of this type, a method of changing the intensity of light for exposing a photoconductor or changing an area of a cross section of light has been used.

The technique disclosed in Japanese Examined Patent Publication No. 60-7780 is one of them.

In this technology, modulated laser light is deflected to a recording width by a rotating polygon mirror or the like and linearly exposed on the photoconductor, and an optical system that changes the cross-sectional area of the laser beam is used to expose the photoconductor on the photoconductor. The halftone is recorded by changing the area of 1 dot.

The optical system that changes the cross-sectional area of this laser beam is the sixth
As shown in the drawing, the light beam from the laser light source 2 is expanded by the beam expander 3 and the incident aperture 4a of the entrance slit plate 4 is illuminated as it is as a parallel light beam. Incident aperture 4
Similarly, a is provided at a position optically conjugate with the exit aperture 5a also provided on the exit slit plate 5 and the imaging lens 6.

A is on the optical path between the imaging lens 6 and the exit aperture 5a.
An O element 7 is provided.

When a light beam is incident on the AO element 7, it causes Gragg diffraction, and the direction of the incident beam can be changed. The cross-sectional area of the scanning beam passing through the exit aperture 5a is changed by changing the angle of this Gragg diffraction with a signal from the control circuit.

Problems to be Solved by the Invention However, in halftone recording using such a laser light source, there are problems that the optical system is complicated and expensive, the total optical path length is long, and the apparatus becomes very large. there were.

As a method for solving such a problem, a method using an array light source composed of a large number of point light sources is disclosed in Japanese Patent Laid-Open No.
It is shown in Japanese Patent No. 34739.

In this technique, as shown in FIG. 7, a semiconductor light emitting element array 8 in which a large number of point light sources are arranged in a line
Is provided in a direction perpendicular to the moving direction of the light source, and each light source is turned on or off according to a signal from the control circuit 9 to expose the surface of the photoconductor 1.

This method has a short total optical path length and a simple imaging optical system and can be downsized, but it is difficult to change the light emission intensity and the light emitting area of the light source, and it is difficult to record halftones. Was not suitable.

Means for Solving the Problems The present invention intends to reproduce halftone recording by using the semiconductor light emitting element array 8 capable of downsizing the apparatus and simplifying the optical system, and its technical means. Is a system in which each light emitting element is composed of a plurality of light emitting areas, and by selectively controlling the plurality of light emitting areas, the exposure area on the photoconductor is changed to record a halftone.

Operation The effects of this technical means are as follows.

(1) Since the semiconductor light-emitting element array in which a large number of light-emitting elements are arranged in a line and the imaging exposure on the photoconductor with the same-magnification imaging optical system, the total optical path length is short, and the optical system is simple. It is possible to reduce the size and cost of the device.

(2) The optical system has no mechanical moving parts, the image recording position accuracy is high, and the reliability is high.

(3) Halftone can be recorded with a simple structure by selectively controlling the control circuit that drives and controls the semiconductor light emitting element array.

(4) Since each light emitting element array has a plurality of light emitting areas, selective control by the control circuit enables halftone recording with high recording position accuracy.

(5) Area of a plurality of light emitting regions of each light emitting element array,
By forming the image in a predetermined ratio, it is possible to obtain a recorded image with high gradation.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows the overall construction of an electrophotographic recording apparatus based on the negative / positive inversion phenomenon. In the figure, reference numeral 1 is an electrophotographic photosensitive member, which is an endless rotary member and is rotated at a constant speed in the direction of arrow A.

Reference numeral 10 is a corona charger that uniformly positively charges the surface of the photoconductor 1 in the axial direction, 11 is an LED array light source in which a large number of light emitting elements are arranged in a line, and 12 is an LED array light source 1
It is a converging optical fiber array such as, for example, a SELFOC lens array (trade name), which forms the pattern 1 on the photoconductor 1 at an equal size. The LED array light source 11 and the converging optical fiber array 12 are provided parallel to the photoconductor 1 in the axial direction.

A developing unit 13 positively charges the toner and continuously supplies the toner to the developing position of the photoconductor 1.

The photoreceptor 1 whose surface is uniformly positively charged by the corona charger 10 is exposed by the LED array light source 11 that emits a desired pattern in response to a signal from a control circuit (not shown), and the potential of the exposed portion is changed. A reduced electrostatic latent image is formed.

This electrostatic latent image is visualized by the next developing means 13 with the positively charged toner attached to the exposed portion of the photoconductor 1.

The toner image on the photoreceptor 1 is transferred to the next corona charger 14 for transfer.
Is transferred onto a sheet of paper 15 conveyed from a sheet feeding section (not shown), and then a cleaner section 16 removes residual toner,
The entire surface is exposed by the static eliminator 17, returning to the initial state.

The paper 15 on which the toner image is transferred is separated from the photoconductor, and then heated and fixed by a fixing unit (not shown) and discharged.

FIGS. 1A to 1C show a light emitting part pattern of an LED array light source 11 for performing halftone recording, which is an essential part of the present invention.
The figure shows the configuration of the control circuit.

As shown in FIG. 1A, the LED array light source 11 is a combination of a first light emitting element 1a and a second light emitting element 1b having a part open around the first light emitting element 1a. The elements correspond to one recording dot and are regularly arranged at a desired recording pitch P. Each light emitting element pair is an electrode 1
It is connected to the control circuit 18 by a'and 1b '.

For example, 1 sent from an external information means such as a computer
The image information recording signal for each line is distributed to each LED by the control circuit 18. At this time, when both 1a 'and 1b' are energized, a pair of LEDs emit light, and the recorded image is 1
When the entire dot is exposed and only 1a 'is energized, the first
Only the light-generating element 1a emits light, and the area corresponding to the area of the first shipping element is exposed.

That is, in halftone recording reproduction, a
The area of one dot for exposing the photoconductor is changed by controlling so that only the rows are energized and the light emitting elements in the row b are not energized.

When the image area per dot is changed and recorded as described above, when all the elements are energized, a solid image as shown in FIG. 4a is obtained.
An image with an intermediate density shown in can be recorded.

Further, by energizing only the light emitting elements in the row b, it is also possible to obtain an image of an intermediate density in which the central portion of the image of 1 dot is white as shown in FIG. 4c.

Next, another embodiment of the present invention will be described.

FIG. 1b shows a variation of the pattern of the light emitting element.
By forming the second light emitting element 1b so as to surround two sides of the first light emitting element 1a, the second light emitting element 1b is formed.
The pattern width can be widened to facilitate pattern formation.
In this case, the same effect can be obtained even in the halftone recording.

Further, as shown in FIG. 1c, the patterns of the pair of light emitting elements are made to have an uneven area for the first light emitting element 1a and the second light emitting element 1b, and the row a and row b energization are selectively controlled. Then,
It is also possible to reproduce a two-stage halftone density as shown in FIG.

EFFECTS OF THE INVENTION The present invention uses a light emitting element array in which a large number of point light sources are arranged in a line in an optical system, so that the total optical path length is short, the apparatus can be downsized, and a mechanical movable part is provided. In addition, high reliability can be achieved and the following effects are also achieved.

That is, in the present invention, in one dot of the light emitting element array,
The configuration is such that two light emitting elements having different shapes are combined in a pair to selectively control a signal applied to a pair of light emitting elements, and a halftone can be reproduced with a simple configuration.
Gradation can also be improved by making the areas of the pair of light emitting elements uneven.

[Brief description of drawings]

FIGS. 1a, 1b, 1c, 1c, 1c, 1c, 1c, 1c, 1d, 1c, 1c, 1d, 1c, 1c, 1d, and 1c show the pattern of a light emitting portion of an LED array light source for performing halftone recording, which is a main part of an electrophotographic recording apparatus according to an embodiment of the present invention. Principle diagram, FIG. 3 is a circuit diagram of a control circuit of a semiconductor light emitting element array of the device, FIGS. 4 and 5 are diagrams showing halftone images recorded by the device, and FIG. FIG. 7 is a principle diagram of a halftone image forming optical system, and FIG. 7 is a principle diagram of an electrophotographic recording apparatus using a conventional semiconductor light emitting element array. 1 ... Photoconductor, 10 ... Corona charger, 11 ... LED
Array light source, 12 ... Focusing optical fiber array, 13
...... Development section, 14 ...... Transfer corona charger.

Claims (2)

[Claims] 1. An electrostatic latent image carrier, a monolithic light emitting device array in which a plurality of light emitting devices are arranged in a line in a direction perpendicular to the moving direction of the carrier, and the monolithic light emitting device array is selectively driven. Each of the light emitting elements of the monolithic light emitting element array has two light emitting areas, and one of the two light emitting areas is formed so as to surround a part of the other light emitting areas. With
An electrophotographic recording device configured to control each light emitting area independently. 2. A monolithic light emitting element array in which the areas of the two light emitting regions are formed unevenly.
The electrophotographic recording device according to the item.