JPS6370873A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To obtain good gradation reproducibility by providing plural kinds of light transmission parts by a prescribed rule pattern, and also, providing the whole pattern filter so as to be able to execute a reciprocating movement, so that each erasion pattern can be exposed selectively. CONSTITUTION:On each of light transmission parts provided on a light shielding pattern filter 24 formed by placing many light transmission parts in a prescribed pattern, a prescribed transmissivity level difference is provided between each of them. The whole of the pattern filter is provided so that its reciprocating movement can be executed in the exposure vertical direction, and each light transmission part 31-34 is arranged regularly so as to form plural pieces of erasion patterns whose exposed parts are not superposed to each other, respectively, when the pattern filter has been moved by a prescribed quantity each.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an electrophotographic recording device, and more particularly, to an electrophotographic recording device that is capable of achieving good gradation of images by performing net-like erase pattern exposure. It relates to a photographic recording device.

(Prior Art) Generally, it is widely known that images recorded by an electrophotographic recording apparatus have a problem in reproducibility of gradation.

As a means to improve this gradation, for example, it is described in "Improvement of color reproducibility by dorato erase in electrophotographic color" (July 1985, 2nd Non-Impact Printing Technology Symposium P77-P80). There is something. This device employs a dorato erase method in which a net-like erase pattern is formed using minute light spots from an LED array. In this case, each dot is grouped into a predetermined pattern matrix, and appropriate erase conditions can be obtained by changing the pattern itself depending on the document, or changing the amount of pattern light emission or charging potential. ing.

However, with this method, in order to change the so-called γ characteristic value that determines the correspondence between the original density and the image density, it is necessary to prepare many patterns and select and use them as appropriate. You have to choose one and use it. In addition to this, the device itself also has high density L
It is necessary to install an ED array, LED array controller, driver, etc., making it complicated and expensive.

On the other hand, conventionally, a light-shielding pattern filter in which light transmitting parts are arranged in a predetermined pattern is used, and by irradiating light onto the surface of a photoreceptor as a latent image carrier through this pattern filter, a net-like erase pattern is created. Electrophotographic recording devices that perform exposure have also been developed. Generally speaking, some of these devices use only one pattern filter in order to keep the device simple and inexpensive, but by changing the light emission timing and light emission time depending on the type of document, arbitrary erasure can be performed. There is one that allows you to obtain a pattern.

However, such a conventional apparatus has a drawback in that the light emission timing and light emission time of the light source must be strictly set and controlled with respect to the moving speed of the latent image carrier.

(Objective) Therefore, it is an object of the present invention to provide an electrophotographic recording apparatus that has a simple configuration and can obtain good image gradation.

(Structure) In order to achieve the above object, the present invention provides a predetermined difference in light transmission level between each of the light transmission parts of a pattern filter, and selectively exposes a predetermined erase pattern to light. The pattern filter is installed so as to be movable back and forth, and each light transmitting section forms a plurality of erase patterns whose exposed areas do not overlap each other when the pattern filter is moved by a predetermined amount. They are arranged regularly so that

In an apparatus having such a configuration, a plurality of types of mesh erase patterns are selectively exposed by appropriately moving one pattern filter.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 9 shows an example of a three-color toner copying machine to which the present invention is applied.

In FIG. 9, reference numeral 1 is a glass plate for originals, 2 is an illumination lamp, 3 is a plane mirror, 4 is a roof mirror, 5 is a lens, 6 is a plane mirror, 7 is a color separation filter device, and 8 is a roof mirror. Drum-shaped photoconductive photoreceptor, number 9
is a charger, 11 is an eraser, 12,1
3.14 is a developing device, code 15 is a snow removal lamp, code 16
17 is a transfer drum, 17 is a transfer charger, and 18 is a transfer drum.
Reference numeral 20 indicates a cleaning device, 20 a separation charger, and 21 a separation claw.

As shown in FIG. 10, the eraser 11 includes an LED array 22 in which a large number of minute red light emitting diodes (LEDs) are arranged at a pitch of 2M, a rod lens 23 that converges the irradiated light from the LED array 22, and a rod lens 23 that converges the irradiated light from the LED array 22. A pattern filter 24 installed at the focal point of the light, and a SELFOC lens 25 that forms an image of the light transmitted through the pattern filter 24 onto the photoreceptor drum 8 as a latent image carrier.
It is equipped with

The LED array 22 is turned on by a control circuit as shown in FIG. That is, the rotary encoder 26 (3
600 pulses/one rotation) and a position detection signal S1 from a home position detector 27 configured by combining a photodiode or a phototransistor with a light emitting diode (LED). ．． S2 is provided to a CPLJ (central processing unit) 28. And the above CPU
An output signal S3 from 28 is applied to the LED array 22 through a transmitting device 29, so that the LED array 22 is turned on at a predetermined timing.

The pattern filter 24, as shown in FIG.
It is partitioned into many unit matrices.

Each unit matrix includes three types of unit matrices 24a,
24b and 24c are repeatedly arranged in sequence, and there are three types of unit yatrixes 24a.

One pattern P is constructed by consecutively arranging 24b and 24C. Therefore, the above pattern P
are to be repeated several times in succession.

Furthermore, each of the unit matrices 24a and 24b.

Inside 24C, four types of light transmitting parts 31, 32, 33 and 34 are installed according to a predetermined rule so as to be arranged on all sides. The arrangement relationship of these light transmitting parts 31, 32, 33 and 34 is based on each unit matrix 24a, 24.
B and 24C are different from each other, so that even if the entire pattern filter 24 is moved in parallel, they will not overlap each other. These four types of light transmitting parts 31, 32, 33 and 34 have different light transmittance levels between them,
The light transmitting section 31 is set to have a transmittance of 90%, the light transmitting section 32 is set to a transmittance of 80%, the light transmitting section 33 is set to a transmittance of 70%, and the light transmitting section 34 is set to a transmittance of 55%. has been done.

Note that the pitch between each light transmitting section is set to 200 μm, and the pitch between each unit matrix 24a is set to 200 μm.

The width of 24b and 24c, that is, the matrix pitch is 40
It is set to 0 μm. Further, such a pattern filter 24 is produced by exposing and developing a dot-like pattern on a silver halide photographic film. In this case, a pattern with arbitrary transmittance can be obtained by changing the exposure time for each dot. The brightness of the dots exposed on the above film is 0.26.0.15
．． By setting the values to 0.14, 0.04, o, and 12.0.21, the light transmittance is 55%, 70%, and 80%.

We were able to obtain 90%, 75%, and 60%, respectively.

Such a pattern filter 24 has a pattern P composed of the unit matrices 24a, 24b, and 24C.
The photoreceptor drum 8 is installed so that the direction in which it is connected extends in the width direction (axial direction) of the photoreceptor drum 8.

Further, this pattern filter 24 is connected to the photoreceptor drum 8.
The length is such that at least two matrices extend from both ends of the matrix.

Furthermore, this pattern filter 24 is moved in the width direction (axial direction) of the photoreceptor drum 8 by a parallel movement drive device (not shown) in each unit matrix 24a, 24b, 2.
It is provided so as to be moved back and forth every integer multiple of the matrix pitch (400 μm) of 4c. By lighting the LED array 22 at a predetermined timing through such a pattern filter 24, an erase pattern composed of each pattern P of the pattern filter 24 is repeatedly formed on the photoreceptor drum 8 by exposure. .

In a copying machine having such a configuration, when the copy button is pressed, the photosensitive drum 8 first rotates in the direction of the arrow in FIG.
operates to eliminate static electricity and clean the photoreceptor drum 8. Note that at this time, the transfer drum 16 rotates clockwise following the rotation of the photosensitive drum 8.

Subsequently, the lamp 2 emits light, moves to the left together with the plane mirror 3, and scans the original O with illumination.

At this time, the roof mirror 4 moves at 1/1 of the moving speed of the plane mirror 3.
Moves at a speed of 2. In this way, the image of the document portion illuminated in a slit shape is projected onto the photosensitive drum 8, and an electrostatic latent image is formed.

At this time, if the blue filter of the filter device 7 is disposed in the optical path, the electrostatic latent image formed is a color-separated latent image corresponding to the blue color-separated image of the original image.

Subsequently, the eraser 11 exposes the blue color separation latent image to a predetermined erase pattern. In this case, the pattern filter 24 is fixed at a reference position, and the erase pattern formed at the reference position is exposed.

After being exposed to the erase pattern in this way,
For example, the blue separated latent image is visualized with yellow toner by the developing device 12 to obtain a yellow visible image. On the other hand, the transfer paper S, which is a recording sheet, is distributed, held on the circumferential surface of the transfer drum 16 at an appropriate timing, sent to the transfer section, and first transferred by the transfer charger 17.
The yellow visible image is transferred onto the transfer paper S.

In this way, as the process from the formation of the blue color separation latent image to the transfer of the visible image progresses, the photoreceptor drum 8
It is cleaned by a cleaning device 18. Subsequently, the filter device 7 is rotated by 90 degrees so that, for example, a red filter is placed in the optical path, and the same process as described above is repeated.

At this time, the pattern filter 24 moves 2n-1 times the matrix pitch (n
-1, 2, 3...) For example, 1 pitch (400 μTIL
) is moved and pattern exposure is performed. This results in
An erase pattern different from the previous erase pattern is formed by exposure. Note that the development is performed using the developing device 13.
This is done using cyan toner.

Further, the same process as above is repeated using the green filter of the filter device 7 and the developing device 14 using magenta toner. In this case, the pattern filter 24 is multiplied by 2n (n=1) from the initial reference position.
．． 2.3...) For example, pattern exposure is performed by moving 2 pitches (800 μTrL). As a result, the previous 2
An erase pattern that is different from the previous erase pattern is formed by exposure.

The transfer paper S is separated from the transfer drum 16 by a separation charger 20 and a separation claw 21, and after a visible image is fixed by a fixing device (not shown), it is discharged from the apparatus.

In the image obtained in this way, since the erase exposure location is different for each color image during pattern erasing, it is possible to almost eliminate the deterioration of even fine lines and characters. Further, very good reproducibility of image density gradation can be obtained from a low density part to a high density part of the document.

The pattern filter 44 in the embodiment shown in FIG.
a, 44b, 44c, and 44d, and can be used for up to four colors.

The pattern filter 54 shown in the embodiment shown in FIG.
Four types of unit matrices 54a, 54b.

One filter unit having one pattern P consisting of 54c and 54d is arranged in parallel in multiple stages over a predetermined slit width.

In this way, it is possible to simultaneously form an erase pattern over a wider area by lighting the lamp twice, which is convenient.

Furthermore, the pattern filter 64 in the embodiment shown in FIG.
, 64b, 64c, and 64d are arranged in parallel in multiple stages over a predetermined slit width, but the patterns P are shifted for each stage. I'm trying to make it happen.

Furthermore, the pattern filters 74 and 84 in the embodiments shown in FIGS.
c, 74d and 84a.

84b, 84c, and 84d are provided with three types of light transmitting portions 75, 76, 77, and 85, 86° 87, respectively. These three types of light transmitting parts 75, 76, 77 and 85, 86, 87 have different light transmittance levels between them, and the light transmitting parts 75 and 85 have a transmittance of 90%. The light transmitting parts 76 and 86 are set to have a transmittance of 75%, and the light transmitting parts 77 and 87 are set to a transmittance of 60%.

is provided so as to extend in the feeding direction of the photosensitive drum 8, that is, in the tangential direction perpendicular to the axis thereof, and the entire pattern filters 94 and 104 are moved back and forth in the extending direction of the pattern P. This is what I did.

In each of the embodiments, one filter unit formed by consecutively arranging a plurality of one pattern P is formed on the photoreceptor drum 8.
are arranged in parallel across multiple stages in the width direction.

Note that by installing a diffusion plate on the surface of the pattern filter, uneven brightness of the LED array that is the light source can be removed. Furthermore, by slightly shifting the image formation surface of the SELFOC lens 25 with respect to the surface of the photoreceptor drum 8, the outline of the erase dots can be made somewhat blurred, thereby reducing the roughness caused by exposure of the erase pattern. I can do it.

Furthermore, in the embodiment described above, an LED is used as the light source of the eraser, but a combination of an LCD or LC3 and a light emitting body such as a fluorescent tube may be used, or the rotation of the photoreceptor 8 may be used. A combination of a shutter array that opens and closes periodically and a light emitter may be used.

The present invention is applicable not only to a three-color toner copying machine as in the above-mentioned embodiment, but also to a four-color toner copying machine with black added thereto, and a bale electrophotographic recording device such as a normal black and white copying machine. Needless to say, it is possible.

(Effects) As described above, the electrophotographic recording device according to the present invention has the following advantages:
In order to form multiple types of erase patterns with a single pattern filter, multiple types of light transmitting parts are provided in a regular pattern, and the entire pattern filter is moved back and forth so that each erase pattern can be selectively exposed. Because it is set up so that it is possible to use it, it is possible to use a low-density, coarse, simple, and inexpensive light source, and it is also possible to perform exposure in an erase pattern suitable for each document with a simple control column, and it is possible to perform exposure of erase patterns suitable for each document, even for letters and fine lines. It is possible to prevent deterioration of reproducibility and obtain good gradation reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a pattern explanatory diagram of a pattern filter in an embodiment of the present invention, FIG. 2, FIG. 3, FIG. 4, FIG.
6, 7, and 8 are explanatory diagrams of patterns of pattern filters in other embodiments of the present invention, FIG. 9 is a theoretical side view of a color copying machine to which the present invention is applied, and FIG. 10 is an eraser FIG. 11 is a block diagram of the light emission control circuit. 8... Photosensitive drum, 11... Eraser, 22...
...LED array, 24.44.54.64.74°8
4.94,104...Pattern filter, 24a
~24c, 44a ~44d, 54a ~54d. 64a ~ 64d, 74a ~ 74d, 84a ~ 84
d, 94a to 98d, 104a to 108d... unit matrix, 31 to 34.75 to 77.85 to 87.
...Light transmission part. , where f'Q 734 cause 5 zu u e where? It's a cause

Claims (1)

[Claims] A light-shielding pattern filter consisting of a large number of light transmitting parts arranged in a predetermined pattern is placed near a light source, and a net-like erase pattern is formed by exposing the surface of the latent image carrier to light through the pattern filter. In the electrophotographic recording apparatus, each of the light transmitting parts provided in the pattern filter is provided with a predetermined transmittance level difference between them, and the entire pattern filter is The light transmitting portions are arranged so as to be movable back and forth, and each of the light transmitting portions is arranged regularly so that when the pattern filter is moved by a predetermined amount, a plurality of erase patterns are formed in which exposed areas do not overlap with each other. An electrophotographic recording device characterized by being arranged in the following.