JPH05127482A - Image forming device - Google Patents

Abstract

PURPOSE:To improve the ability to separate a form from a photo-sensitive body by means of the simple configuration by employing toner which is decolorized when receiving a beam of light, as a second toner with the polarity different from a first toner. CONSTITUTION:The image forming device is provided with developing units 10a and 10b which develop an electrostatic latent image formed on a photosensitive drum 9 with image light, a transfer charger 11a which transfers the image developed by the developing unit 10a to a from, a cleaning unit 12 which removes residual toner on the photosensitive drum 9, a main charger 13 which uniformly electrifies the photosensitive drum 9. The developing unit 10b uses toner (decolorization toner) which is decolorized when receiving the light of an erasing halogen lamp 22, for example, the toner containing cyanine-based dye subjected to the reaction with the ammonium salt of organic boron. The developing unit 10b uses toner (ordinary toner) which, even when receiving light, is not decolorized and has the polarity different from that of the decolorization toner.

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 electrophotographic copying machine for forming an image by using a photoconductor.

[0002]

2. Description of the Related Art Conventionally, in such an image forming apparatus, when a toner image on a photoconductor is transferred onto a paper and then the paper is separated from the photoconductor, the paper having a poor separability is used. It is known that a toner having the same color as that of the paper is adhered onto the photoconductor corresponding to the leading end of the paper to improve the separability of the paper (see, for example, Japanese Patent Laid-Open No. 1-92768). ).

[0003]

However, in such a conventional image forming apparatus, in addition to the original developing device for developing the electrostatic image on the photoconductor, the same device as the device for identifying the color of the paper or the paper is used. Since a special developing device for developing the photoconductor with color toners is required, there is a problem that the configuration of the image forming apparatus and its control become complicated. This invention was made in consideration of such circumstances.
To provide an image forming apparatus capable of improving the separability of a sheet from a photoconductor without complicating the configuration and control of the apparatus.

[0004]

According to the present invention, there is provided a first developing device for developing an electrostatic latent image formed on a photoconductor with a first toner, and the electrostatic latent image having a polarity different from that of the first toner. Two
A second developing device that develops with toner, a transfer device that transfers the image developed by the first and second developing devices to a sheet, and a light beam of a specific wavelength on the image surface of the sheet that is transferred and separated from the photoconductor. An image forming apparatus provided with a light source for irradiating, wherein the second toner is a toner that is decolorized when receiving the light beam.

[0005]

When the electrostatic latent image on the photoconductor is developed by the first and second developing devices, the second toner adheres to the area other than the area where the first toner adheres. Therefore, the second toner adheres to the area corresponding to the leading edge of the paper, and the separability of the paper from the photoconductor is improved. Further, when the paper separated from the photoconductor receives the light of a specific wavelength, the second toner is decolorized, so that only the image formed by the first toner remains on the paper.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. This does not limit the invention. FIG. 1 is an explanatory view of the configuration of an electrophotographic copying machine showing an embodiment of the present invention, in which 1 is a contact glass for placing a document, 2 is a document cover, 2a is a document holding mat, and 3 is a document exposed. Exposure lamp, 4 is an imaging lens,
Reference numerals 5 to 7 denote mirrors that guide the image light from the document exposed by the exposure lamp 3 to the imaging lens 4.
Is moved in the direction of arrow A to scan the document, the mirror 5
7 to 7 are moved so that the optical path length from the document to the imaging lens 4 is always constant.

A mirror 8a, 10a, 10 reflects the light from the imaging lens 4 and forms an image of the image light on the photosensitive drum 9.
b is a developing device for developing the electrostatic latent image formed on the photosensitive drum 9 by the image light, 11a is a transfer charger for transferring the image developed by the developing device 10a to paper, 11
Reference numeral b is a transfer charger that transfers the image developed by the developing device 10b onto a sheet, 12 is a cleaning unit that removes residual toner on the photosensitive drum 9, and 13 is a main charger that uniformly charges the photosensitive drum 9. ..

Further, 14 and 15 are paper feed cassettes, 16 is a transport path for transporting paper from the paper feed cassettes 14 and 15 toward the photoconductor drum 9, and 17 is a rotation path of the photoconductor drum 9 provided in the transport path 16. A registration roller that determines the paper feed timing for the registration roller 18 and a registration switch 18 that is provided in the vicinity of the registration roller 17 and detects that the paper has reached the registration roller 17.

Numeral 19 is a conveyor belt for conveying the transferred sheet to the fixing device 20, and numeral 21 is a sheet ejection roller for ejecting the fixed sheet. An erasing halogen lamp 22 is provided on the conveyor belt 19 and irradiates the paper conveyed by the conveyor belt 19 with light of a specific wavelength.

The developing device 10b contains a toner that is decolorized when it receives the light from the erasing halogen lamp 22 (hereinafter referred to as a toner that disappears), for example, a toner containing a cyanine dye that has been reacted with an ammonium salt of organic boron. Toner (hereinafter, referred to as normal toner) that is used and does not decolorize even when receiving light is used for the developing device 10a.

Further, these toners have polarities different from each other, and the toner of the developing device 10b adheres to the light-exposed portion (non-charged portion) on the surface of the charged photosensitive drum 9 and the toner of the developing device 10a. Is attached to a portion not exposed to light (charged portion).

FIG. 2 is a block diagram showing a main part of the control circuit of the embodiment shown in FIG. 1, where MC is a control unit incorporating a microcomputer, KB is a keyboard for inputting various copying conditions, and TC is a copying process. A timer counter for management, PS1 is a primary paper feed drive unit for driving the primary paper feed system from the cassette 14 or 15 to the registration roller 17, PS
Reference numeral 2 denotes a secondary paper feed drive unit that drives a secondary paper feed system from the registration roller 17 to the paper discharge roller 21, PS3 denotes an optical system drive unit that drives an optical system such as the exposure lamp 3 and mirrors 5 to 7, and JS. Is a jam detection sensor that detects a paper jam (paper jam), and DP is a display unit that displays various copying conditions and conditions.

The control unit MC receives outputs from the keyboard KB, the registration switch 18 and the jam detection sensor JS, and receives a timer counter TC, an erasing halogen lamp 22, a primary paper feed drive unit PS1, and a secondary paper feed drive unit. P
S2, the optical system drive unit PS3, the display unit DP and the main charger 13, and the transfer chargers 11a and 11b are output.

The operation in such a configuration will be described with reference to the flow chart shown in FIG. First keyboard KB
When "copy start" is input from the
S1 is driven to convey the sheet from the cassette 14 or 15 to the registration roller 17 (step 101). If there is no jam at this point (step 102),
The timer counter TC starts timing (step 10
5) At the same time, the first development image forming process and the second development image forming process are started (steps 103 and 104). In other words, the optical system drive unit PS3 is driven to perform the exposure scanning of the document by the exposure lamp 3, and the electrostatic latent image formed on the photosensitive drum 9 is continuously developed by the developing devices 10a and 10b. It

On the other hand, when the timer counter TC finishes counting the predetermined time, the secondary paper feeding drive unit PS2 is driven to convey the paper from the registration roller 17 toward the photosensitive drum 9 (step 106). At this point, if no jam occurs (step 107), the developed image is transferred to the sheet by the transfer chargers 11a and 11b (steps 108 and 109).

Then, when the timer counter TC measures a predetermined time (step 110) and no jam occurs (step 111), the paper is conveyed by the conveyor belt 1.
It is conveyed to the fixing device 20 by 9 and fixed (step 112). The sheet conveyed by the conveyor belt 19 is exposed by the erasing halogen lamp 22 and the portion of the developing device 10b developed with the disappearing toner is erased. If a jam occurs in steps 102 and 111, the operation of each unit is stopped and the display unit DP
Performs "jam display".

By the above operation, when a document as shown in FIG. 4 is copied, for example, the portion of the letter "A" of the document is developed with normal toner, and the other portion (hatched portion in FIG. 5) disappears. Developed with toner. Therefore, the toner that disappears adheres to the portion of the photoconductor drum 9 corresponding to the front end of the paper, so that the separability of the paper is improved and the paper after transfer is easily separated from the photoconductor drum 9.

Since the paper on which the toner image shown in FIG. 5 is transferred is exposed by the halogen lamp 22 as described above, the toner in the shaded area is erased, and the fixed image is as shown in FIG. Become.

FIG. 6 is a structural explanatory view showing a main part of a modified example of this embodiment. As the fixing device 20, a heating roller 20c made of a heat-resistant transparent resin pipe 20a having a halogen lamp 20b built therein, and a sheet of paper on the heating roller. When a fixing device including a pressure roller 20d that conveys while pressing the
Because it is done at the same time as fixing and exposing the paper,
The erasing halogen lamp of FIG. 1 becomes unnecessary.

[0020]

According to the present invention, it is possible to improve the separability of the paper from the photoconductor with a simple structure.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a control circuit of the embodiment.

FIG. 3 is a flowchart showing the operation of the embodiment.

FIG. 4 is an explanatory diagram showing an image used in an example.

FIG. 5 is an explanatory diagram showing a toner adhesion state of a sheet of the embodiment.

FIG. 6 is a configuration explanatory view showing a main part of a modified example of the embodiment.

[Explanation of symbols]

 1 Contact Glass 3 Exposure Lamp 9 Photoreceptor Drum 10a Developing Device 10b Developing Device 11a Transfer Charger 11b Transfer Charger 19 Conveyor Belt 22 Erasing Halogen Lamp

Front Page Continuation (72) Keiichi Nagahashi 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd.

Claims (1)

[Claims] 1. A first developing device for developing an electrostatic latent image formed on a photoconductor with a first toner; and a first developing device for developing the electrostatic latent image.
Second developing with a second toner having a polarity different from that of the toner
A developing device, a transfer device that transfers the image developed by the first and second developing devices to a sheet, and a light source that irradiates the image surface of the sheet that is transferred and separated from the photoconductor with a light beam of a specific wavelength, An image forming apparatus in which the second toner is a toner that decolorizes when receiving the light rays.