JPH05124258A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To make it possible to form an image with excellent quality of printing by means of the title apparatus of a small size, being inexpensive and with a high speed by exposing a paper wherein a color-disappearing toner is wholly developed with a laser beam at a timing corresponding to a bright and dark image of a manuscript and writing thereby an image of the manuscript. CONSTITUTION:In an irradiating range of a laser beam irradiated from a laser diode 61, a collimator lens 62 making the dispersing laser beam into a cylindrical parallel light is collimator lens 62 is made to be an incident light to a mirror face of a polygon mirror 63 rotating in the arrow mark direction around the vertical axis and a laser beam LB is formed by means of the mirror face. Then, the laser beam LB is corrected in such a way that the beam diameter is made into a definite dimension by means of a lens 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrostatic copying machine or a printer, and more particularly to an image forming apparatus which does not require a device such as a photosensitive drum or a charger.

[0002]

2. Description of the Related Art As an information recording (printing) method for image forming apparatuses such as copying machines and printers, the following methods have been put into practical use.

Electrophotographic system Inkjet system Thermal system Electrostatic recording system Wire impact system

[0004]

However, the above-mentioned image forming method has the following drawbacks.

Since the electrophotographic system requires processes such as charging, exposure, development, fixing, cleaning and charge removal, a charger, an exposure optical system, a developing device, a fixing device, a cleaning device and a charging device are used to perform these processes. A static elimination lamp is required. A photoconductor drum and toner are also required. For this reason, the electrophotographic method has drawbacks that the apparatus configuration becomes complicated and the size becomes large.

[0006] The ink jet system has drawbacks that the recording speed is slow and the product price is high.

The thermal system has a drawback that the recording speed is slow and the printing quality is poor.

The electrostatic recording method has the drawbacks that the price of electrostatic recording paper is high and the running cost is high.

The wire impact method has a drawback that noise is generated during recording and print quality is poor.

For the above reasons, at present, there is a demand for realization of an image forming apparatus which is small in size, inexpensive, and high in printing quality at high speed.

The present invention has been made in order to meet such a demand, and an object of the present invention is to provide a new type image forming apparatus capable of solving various drawbacks of the conventional method.

[0012]

SUMMARY OF THE INVENTION An image forming apparatus of the present invention comprises a developing means for developing a decolorizable toner contained in a developing unit onto a sheet, and a sheet on which the decolorizable toner is developed. And a laser writing unit that writes a document image by exposing a laser beam at a timing corresponding to a light and dark image of the document, thereby achieving the above object.

[0013]

[Function] As this type of decolorizable toner, there are the following ones announced by Showa Denko KK. This color erasable toner contains at least a color erasable dye, a binder resin and a white pigment, is blue when not exposed to light of near infrared wavelength, and white when irradiated with light of near infrared wavelength. It will be.

Examples of such decolorizable dyes are organic boron compound salts of cyanine dyes, and the following compounds can be exemplified.

[0015]

[Chemical 1]

[0016]

[Chemical 2]

[0017]

[Chemical 3]

[0018]

[Chemical 4]

[0019]

[Chemical 5]

The above-described decolorizable dye has an absorption maximum at a near infrared wavelength, typically 810 to 830 nm, and in particular absorbs light near 820 nm to be decolored and becomes white.

As the binder resin, a resin material conventionally used as a binder resin for electrophotographic toner can be used. For example, polystyrene, polystyrene-butadiene copolymer, styrene-based copolymers such as styrene-acrylic copolymer, polyethylene, polyethylene-vinyl acetate copolymer, ethylene-based copolymers such as polyethylene-vinyl alcohol copolymer, Examples thereof include phenolic resins, epoxy resins, allyl phthalate resins, polyamide resins, polyester resins, maleic acid resins. These compounds may be used alone or in combination of two or more.

Therefore, when the decolorizable toner is developed on the entire surface of the sheet by the developing means, the sheet becomes blue. From this state, when the semiconductor laser of the laser writing unit (for example, a laser diode that emits a laser beam including near-infrared wavelength) exposes the laser beam at a timing corresponding to the light and dark image of the original, the exposed portion changes from blue to blue. Turns white.

Therefore, if the paper is exposed to the laser beam at a timing corresponding to the dark portion (printing portion) of the document, the portion of the paper corresponding to the printing portion of the document will be white, so that white printing is performed on the paper. Is done. On the other hand, when the laser beam is emitted at the timing corresponding to the bright portion (non-printing portion) of the document, the portion of the sheet corresponding to the non-printing portion of the document becomes white, and in this case, blue printing is performed. ..

This can be easily realized by inverting the ON / OFF timing of the laser diode for emitting the laser beam by the negative / positive inverting circuit.

[0025]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 shows the overall construction of a digital copying machine to which the present invention is applied. Below the platen 1 made of transparent glass, a halogen lamp 20 serving as a light source lamp and a first lamp
The scanner 2 provided with the mirror 21 is disposed so as to be capable of reciprocating in the arrow A direction and the opposite direction. Scanner 2
Scans the document placed on the document table 1 optically. That is, the light emitted from the halogen lamp 20 to the original is reflected by the original, and then reflected by the first mirror 21 in the direction opposite to the arrow A direction, and the second mirror 23 and the third mirror 24 are vertically arranged. It is guided to the mirror unit 22.

The mirror unit 22 changes the optical path of the reflected light guided to it in the direction opposite to the arrow A direction. In this way, the reflected light whose optical path has been changed is guided to the ISU substrate 4 via the lens 25. The ISU board 4 converts the reflected light from the original document into an electric signal, and supplies the electric signal to the IPU board 5 serving as an image processing unit.

The IPU board 5 processes the data such as editing, reversing, moving, and enlargement / reduction ratio of the original 3 with electric signals, and performs image processing to generate image data. IPU board 5
The image data generated by is supplied to the laser writing unit 6.

FIG. 2 shows the structure of the laser writing unit 6. This laser writing unit 6 includes an IPU board 5
The laser beam emitted from the laser diode 61 in response to the ON / OFF signal given by the scanner is scanned by the polygon mirror 63 as a laser beam LB of data for one line in the sub-scanning direction of the document, and the laser beam LB is reflected. A basic configuration is adopted in which the lower sheet P (see FIG. 1) is exposed via the mirror 66 and the image data for one line corresponding to the original image is sequentially written on the sheet P.

Explaining the configuration in detail, the emission area of the laser beam emitted from the laser diode 61 is as follows.
A collimator lens 62 for collimating the diffused and emitted laser beam into a cylindrical parallel light is provided. The laser beam collimated by the collimator lens 62 is incident on the mirror surface of the polygon mirror 63 that rotates in the direction of arrow B about the vertical axis, and the laser beam LB is generated by the mirror surface. Subsequently, the laser beam LB is corrected by the fθ lens 64 so that the beam diameter becomes constant. This correction is performed so that the scanning speed of the laser beam LB becomes equal at any position on the paper surface of the paper P.

Then, the corrected laser beam LB is subjected to horizontal tilt correction by the cylindrical lens 65. This tilt correction is performed so that the laser beam LB is always exposed perpendicularly to the paper P, and thus the problem that the laser beam LB is curved can be prevented. The laser beam LB after being subjected to the inclination correction has its optical path converted vertically downward by the reflection mirror 66, and is exposed on the paper P.

In addition, a reflection mirror 67 for reflecting a part of the laser beam LB on the laser detection substrate 68 is disposed outside one end of the reflection mirror 66 in the longitudinal direction. Upon detecting the laser beam LB, the laser detection board 68 feeds back a laser detection signal (RB) to the IPU board 5. The IPU board 5 determines the timing of a horizontal synchronizing signal (HSYNC) for image writing based on the laser detection signal, and the laser diode 6 based on the horizontal synchronizing signal.
The ON / OFF timing of 1 is set.

As shown in FIG. 1, the paper (plain paper) P in the paper feed cassette 7 is conveyed to the exposure area of the laser beam LB in synchronization with the scanning of the scanner 2. Specifically, this transportation is performed as follows. That is, the rotation of the paper feed roller 8 disposed above the front end of the paper feed cassette 7 feeds the uppermost paper P of the multiple papers P stacked in the paper feed cassette 7 into the machine. .. Subsequently, the paper P is transported to the position of the developing unit 9 arranged on the downstream side of the paper feed cassette 7 (downstream side in the transport direction of the paper P).

In the developing unit 9, a decolorizable toner T (see FIG. 3) made of the material described in the above-mentioned operation is stored, and the decolorable toner T is in a positive state in the developing unit 9. Is frictionally charged. Subsequently, the decolorizable toner T is developed over the entire surface of the paper P by the cooperative action of the developing sleeve 90 in the developing unit 9 and the auxiliary roller 10 provided below the developing sleeve 90. ..

FIG. 3 shows this developing principle. As shown in the figure, the auxiliary belt 10 is grounded, and when a positive developing bias voltage is applied to the developing sleeve 90, the positive decolorizable toner T is developed on the paper P by the bias voltage. It has become so.

On the downstream side of the developing unit 9, there is provided a conveyor belt 11 for conveying the paper P having the decolorizable toner T developed on its entire surface toward the downstream side. An exposure area of the laser beam LB is set at an intermediate portion in the longitudinal direction corresponding to the transport direction of the transport belt 11. Therefore, as the sheet P is conveyed to the downstream side, the sheet P is sequentially exposed from the front end side.

When the laser beam LB is exposed, the paper P
Since the exposed part of changes from blue to white,
An image corresponding to the original image is formed on the sheet P. The image area of the paper P may be exposed to the laser beam LB to perform white printing, or conversely, the laser beam LB may be applied to the non-image area.
Alternatively, blue printing may be performed by irradiating.

The sheet P on which the image is formed is the conveyor belt 11
Is continuously conveyed to the downstream side and is supplied to the fixing device 12. The fixing device 12 performs a fixing process of the decolorizable toner T after being developed on the paper P and exposed to the laser beam LB. The paper P that has undergone the fixing process is discharged onto the discharge tray 13.

In the above embodiment, the case where the present invention is applied to a digital copying machine has been described, but it goes without saying that the present invention can be widely applied to electrostatic copying machines in general and other images such as printers and facsimile machines. The same applies to the forming device.

[0040]

According to the above-described image forming apparatus of the present invention, the image forming process is performed by the step of developing the decolorizable toner on the sheet and the step of exposing the sheet after development with the laser beam. Therefore, the process can be remarkably simplified as compared with the electrophotographic system which requires a series of image forming processes such as charging, exposure, development, cleaning and charge removal. Therefore, devices such as a charger, a photoconductor drum, a transfer charger, and a cleaning device are not required, and the device configuration can be simplified, miniaturized, and lightweight, which is an advantage that an inexpensive image forming device can be realized.

Further, as compared with an ink jet type image forming apparatus or a thermal type image forming apparatus, there is an advantage that the recording speed can be improved.

[Brief description of drawings]

FIG. 1 is a front sectional view showing the overall configuration of a copying machine to which the present invention is applied.

FIG. 2 is a perspective view showing the configuration of a laser writing unit.

FIG. 3 is a principle explanatory view showing a printing principle of the present invention.

[Explanation of symbols]

 2 Scanner 5 IPU substrate 6 Laser writing unit 61 Laser diode 63 Polygon mirror 66 Reflecting mirror 9 Developing unit 90 Developing sleeve 10 Auxiliary roller 11 Conveying belt LB Laser beam P Paper T Decoloring toner

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Nakano 1-22 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd. (72) Masai Inoue 1-22 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Inventor Kazuhiko Yamamura 1-22 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A developing means for developing the decolorizable toner contained in a developing unit on the entire surface of a sheet, and a laser beam at a timing corresponding to a light and dark image of an original on the sheet on which the decolorizable toner is entirely developed. An image forming apparatus including a laser writing unit that exposes an image to write an original image.