JPS61165782A - Device for double mode electronic photograph - Google Patents

Abstract

PURPOSE:To obtain an erasing means which will not need a modulating signal and a memory by assembling a print head with a light shutter and a light source, constituting it by a light emitting diode array and making selectively respective elements into an action condition by the copy mode. CONSTITUTION:At a print head 100, a long straight line-shaped light source 101 is provided in the width direction of a photosensitive body 2 and at a falling-on side of a self-focusing lens 102, a light shutter array 103 is provided. When the copy mode is selected, the head 100 is operated as an eraser, outputs a PRESETALL and ENABLE signals until the tip of the picture image is projected, and makes all elements of the light shutter array 103 into the light transmitting characteristic and executes the whole width erasing. When the tip part of the picture image is detected, an RESET a-c signals are outputted in accordance with the original sizes a-c, the elements of the part equivalent to widths a'-c' are reset, and only the part except the widths a'-c' is erased. When the rear edge of the picture image is detected, the PRESETALL signal is outputted again, the whole width is erased between the rear edge and a certain distance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a dual mode electrophotographic apparatus that can be used as an electrophotographic copying machine and as an electrophotographic printer.0 (Prior Art) Electrophotography Copying machines project an image from a document onto a charged photoreceptor and selectively discharge the charges to form an electrostatic latent image, whereas electrophotographic printers Although they differ in that an electrostatic latent image is formed by selectively discharging charges by scanning a photoreceptor with modulated light, the other configurations are common to both. The dual mode electrophotographic apparatus is equipped with the two electrostatic latent image forming means.

By the way, when a dual mode electrophotographic device is used in print mode, only the area where the signal exists is left and the rest is exposed, so toner adheres to areas other than the image area and that area becomes completely black. However, if the copy mode is used and the white document holder is not used, the area on the copy corresponding to the periphery of the document will be completely black. In order to prevent this, in a dedicated copying machine, an erase lamp is turned on to remove the charge from unnecessary parts, but a dual mode electrophotographic apparatus also requires an erase means in the copy mode.

In the device described in Japanese Patent Application Laid-Open No. 52-67332, as the erasing means, a laser beam, which is an exposure means of a printer, is irradiated to a region other than the image forming area to remove unnecessary charges in that region. .

The method described in the above publication uses a laser beam scanning mechanism as an erase means, which is unnecessary in the copy mode, so it has the advantage of not requiring a dedicated eraser. Since scanning is performed repeatedly in the width direction while modulating accordingly, a modulation signal corresponding to the size of the document is required, and a memory and reading means for storing it are required.

(Objective) It is an object of the present invention to provide an erasing means that does not require the modulation signal or memory.

(Structure) In order to achieve the above object, the present invention uses the known electrostatic latent image forming means in print mode.
The present invention is characterized in that a means for modulating light from a light source by an optical shutter array or a light emitting diode array is used, and this electrostatic latent image forming means is also used as an erasing means in the copy mode.

Next, a detailed description will be given based on an embodiment shown in the accompanying drawings. 2 is a belt-shaped photoreceptor, and pulleys 3 and 4
It is wrapped around and runs endlessly. 100 is a print head using an optical shutter array;
They operate selectively with the original image exposure system 05 to form electrostatic latent images on the photoreceptor 2, respectively. This electrostatic latent image is developed by the developing device 1 and transferred to the transfer paper by the action of the transfer charger 90. P and -P are transfer paper cassettes of various sizes, and the transfer paper selectively fed from these by paper feed rollers 10-1 to 10-3 is timed by registration rollers 12, The transfer charger 90 advances to the active area. The transferred paper is transferred to the fixing device 1.
3, and is discharged onto a tray 15 by a paper discharge roller 14. The transferred photoreceptor 2 is statically removed by a static eliminator 8,
After the residual toner is removed by the cleaning device 7, it is uniformly charged by the charger 6 as the first stage of the next electrostatic latent image forming process.

In the print mode, the original image exposure system is in a dormant state and the print head 100 is in an operating state. The print head 100 includes linear light sources 101 that extend in the width direction of the photoreceptor 2 and are arranged in a staggered manner to focus the light from the light sources 101 on the photoreceptor 2 as a number of spots. The selfoc lens 102 includes a large number of selfoc lenses 102, and further includes an optical shutter array 103 on the incident side of the selfoc lens 1020. The optical shutter array 103 is a known one (see Japanese Patent Application Laid-open No. 168468/1983) that includes a shutter element made of liquid crystal that turns on and off the light incident on each SELFOC lens 102. As shown in FIG. 2, in the print mode, the data input signal is input to the bit driver together with the clock, ENABLE, and 5TROBE signals, and the optical shutter array 1
03 are selectively turned on. The turned-on liquid crystal element becomes translucent and transmits light from the light source 101 to the photoreceptor 2 through the SELFOC lens 102, thereby lowering the charged potential of that portion. Since the liquid crystal element that remains off blocks light from the light source 101, the charged potential at the corresponding position does not decrease, and an electrostatic latent image is formed.

In the copy mode, the print head 100 operates as an eraser, and the original image exposure systems 300 to 305 are in operation as electrostatic latent image forming means. Reference numeral 300 is a contact glass, on which a light source 301 illuminates an original, and the reflected image is reflected by a mirror 302,
An optical system consisting of 303, 304 and a lens 305,
It is projected as a slit image onto the photoreceptor z to generate an electrostatic latent image.

The projection area of the original image onto the photoreceptor 2 varies depending on the size of the original, and when the image is based on the center, it is as shown in Figure 3, and when it is based on the edges, it is as shown in Figure 4. It becomes like this. That is, the projection areas of each document of maximum size α, medium size b, and minimum size C overlap with their leading edges aligned, and there are non-image areas, that is, static neutralization, outside on both sides of each width α/, h/, and C/. There will be areas where you should do something.

Further, the area in front of the tip and the area behind each rear end is a region where static electricity should be eliminated throughout the eclipse. Information on the document size is detected by a sensor (not shown) provided on the contact glass 300, and is input to the bit driver via a control circuit. Therefore, the control circuit is as shown in Figure 5.
Lock, ENABLE, 5T required in print mode
ROBE o and others, RESETa, b, c and PRES
Each signal of ETALL is given to the bit driver. The PRESETALL signal presets the optical shutter array 103 via the dot driver,
All of the liquid crystal elements constituting the photoreceptor 2 are turned on to make them translucent, and the photoreceptor 2 is erased throughout its erasure. The timing of generation of this signal is selected and given depending on the timing of the copy S cycle and the document size. RESETa,b,
Each signal c is selected and output according to the document size, and performs a reset operation on the portions of the liquid crystal elements of the optical shutter array 103 corresponding to α', b', and C'. and turn it off to make it blackout.

FIG. 6 is a flowchart showing the operation of the present invention.

When copy mode is selected, the print head 100
It operates as an eraser and performs steps 1 to 3.

Step 1: Until the leading edge of the image from the original is projected, the PRESE'EALL and ENABLE signals are output, and all elements of the optical shutter array 103 are made translucent to perform full-width erasing.

Step 2: When the leading edge of the image from the original is projected (or the leading edge is detected), RESEIα to C signals corresponding to the original size α to CK are output, and the width α
The elements corresponding to ' to C' are reset and made light-shielding. As a result, only the portions other than the widths α' to C' are erased.

Step 3: When the trailing edge of the image is detected (or at its timing), the PRESERG ALL signal is output again, erasing is performed for a certain distance from the trailing edge, and then the ENABLE signal is output. is cut off and all elements are turned off.

In print mode, the print head 100
It performs its original function and performs the operations in steps 4 to 6.

Step 4 is similar to step 1.

Step 5: Each element of the optical shutter array 103 is selectively reset by a data signal from an external device (word processor, facsimile, etc.), and the corresponding portion becomes in a printing state.

Step 6: Same as step 3.

In addition, as the optical shutter array 103, PLZT, L
There is an IS-LCD, etc., and instead of using it and the light source 101, a light emitting diode playback may be used and the light emitted by it may be utilized.

(Effects) As described above, in the present invention, since the print head in the print mode is constituted by an optical shutter array or a light emitting diode array consisting of a large number of elements arranged in parallel in the width direction of the photoreceptor, during the erase operation, Unlike the prior art described above, there is no need for scanning, no data for that purpose, no memory for storing the data, and no means for reading the memory, and the dedicated eraser can be omitted.

Still, the erase range can be easily changed in accordance with enlarged or reduced copies.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is a block diagram of the print head control circuit, FIGS. 3 and 4 are plan views showing the image forming area on the photoreceptor, and FIG. Figure 5 is a block diagram of the control circuit for the print head and eraser.
The figure is a flowchart for explaining the operation of the present invention. 2... Photoreceptor, 100... Print head, 101
... Light [,103... Optical shutter array. Patent applicant Rico Co., Ltd. - Figure 4 Figure 5

Claims (3)

[Claims] (1) Expose the photoreceptor to a slit image from the original,
In an electrophotographic apparatus having a copy mode for recording an electrostatic latent image of a document, and a print mode for recording an electrostatic latent image on the photoreceptor by a print head supplied with a data signal, the print head is connected to the photoreceptor. The eraser is constructed by a combination of a light shutter array consisting of a large number of elements arranged in parallel in the width direction and a light source, or a light emitting diode array, and by selectively activating each element in the copy mode. A dual mode electrophotographic device characterized by: (2) The dual mode electrophotographic apparatus according to claim 1, wherein the operating range of each element of the optical shutter array or the light emitting diode array is controlled according to the original or copy size. (3) The operation timing of each element of the optical shutter array or the light emitting diode array is controlled according to the document or copy size. Heavy mode electrophotographic equipment.