JPH07128961A - Original-platenless copying machine - Google Patents

Abstract

PURPOSE:To provide an inexpensive, original-platenless digital copying machine. CONSTITUTION:The digital copying machine is equipped with an image forming device which electrifies a photoreceptor 21, using a transparent base material, by bringing electrified toner, stired in a toner development tank, with the photoreceptor, and an optical writing element 27, disposed inside the photoreceptor 21, which is used for optical writing from inside. The digital copying machine is further equipped with an image-reading sensor 36 provided so as to read an original digitally, an original-electrifying device which electrifies the contact surface of the photoreceptor 21 with the original, and a means for directly attracting and fixing the original which is to be copied, to the electrified surface of the photoreceptor 21 by an electrostatic force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a platenless copying machine, and more particularly to a digital copying machine which is improved without a platen.

[0002]

2. Description of the Related Art In a conventional digital copying machine, a digital image read by an image reading sensor is subjected to various kinds of image processing, and then a digital image signal is optically written on a photosensitive member by an optical writing device (semiconductor laser unit, light emitting diode, etc.). Then, a latent image is formed on the surface of the photoconductor, and the charged toner is brought into contact with the latent image to visualize the latent image. Then, the toner image is transferred onto the transfer paper and thermally fixed. In this case, as a reading method and a writing method, many means have already been proposed and put to practical use.

On the other hand, various proposals have already been made for image forming means using a photoconductor using a transparent substrate. For example, in Japanese Examined Patent Publication No. 2-4900, a photoreceptor is provided with a translucent conductive layer, a photoconductive layer, and an insulating layer in this order, and a voltage is applied while supplying a conductive magnetic toner to the insulating layer side. While exposing the photoconductive layer, the toner is attracted to the surface of the photoconductor by electrostatic force in the light area, and the toner is removed after the exposure in the dark area so that the toner adheres to the exposed light area on the photoconductor. A means for forming an image has been proposed. Further, in Japanese Patent Publication No. 3-64864, a photoconductor in which a photoconductive layer is integrally provided on a light-transmitting conductive layer is used, toner is supplied to the conductive layer side of the photoconductor, and a voltage is applied between the two. A means for irradiating image light from the side of the conductive layer while applying and electrostatically adhering the toner to the bright portion to form an image has been proposed.

[0004]

By the way, in any of the conventional methods described above, a dedicated document table for reading a document is required. Furthermore, since the document table is required, a moving means for optically moving the image reading sensor along the document is required. Further, since the reading device is provided, it is necessary to take a space in the optical path, and the copying machine becomes large. Therefore, it has a disadvantage that it leads to higher prices of products. Therefore, the object of the present invention is to eliminate the need for a dedicated document table and the need to move the image reading sensor along with the document.
An object of the present invention is to provide a low-cost copyboard-less copying machine having a compact and simplified structure.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the gist of the present invention is to agitate a photosensitive member using a transparent substrate in a toner developing tank. And an image reading device provided with an optical writing element for electrically charging the charged toner by bringing the charged toner into contact with the inside of the photoconductor, and an image reading sensor provided so as to digitally read a document. In a digital copying machine having the same, a document table having a document charging device for charging the contact surface of the photoconductor with the document and having a means for directly attracting and fixing the document to be copied to the charged surface of the photoconductor by electrostatic force It is in a less copier.

[0006]

In the present invention, attention is paid to the fact that the upper part of the photoconductor has not been used so far, and this photoconductor surface is effectively utilized. The photoconductor surface is provided on the upstream side of the contact surface with the original. A charging device is provided to charge the contact surface, and the original is directly attracted and fixed to the charged surface of the photoconductor by electrostatic force to read the original, so that no original table is required and the image reading sensor is moved. Since it is not necessary, the driving device thereof is also unnecessary, and the optical reading optical path becomes short, so that the device can be downsized as a whole. Further, the original can be read in synchronization with the speed of the photoconductor, and the synchronization between the reading and the optical writing can be easily ensured.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a schematic explanatory view showing the basic configuration of a document tableless copying machine of the present invention. In FIG. 1, reference numeral 21 is a photoreceptor (OPC) drum using a transparent base material. This photosensitive drum 21 is rotatable in the E direction,
On the surface of an optically transparent cylindrical transparent support (glass),
A transparent conductive layer and a photoconductive layer made of a photoconductive material are sequentially laminated and configured. In this case, as the transparent conductive layer, for example, an In ₂ O ₃ layer having a film thickness of about 0.5 μm is formed by a sputtering method of In ₂ O ₃ , and as the photoconductive layer, an amorphous film having a film thickness of, for example, 3 μm is used. Those having a Si layer are suitable. The transparent conductive layer is not limited to the In ₂ O ₃ layer, and SnO ₂ layer may be used in other cases. Further, the photoconductive layer is not limited to the amorphous Si layer, and may be made of any material exhibiting photosensitivity, such as Se layer and ZnO.
Layers or CdS layers are preferred.

Next, in FIG. 1, 27 is an exposure device (exposure means) composed of an LED array, and a plurality of light emitting elements (light emitting diodes) are arranged in parallel along the width direction of the photosensitive drum 21. It has been done. Reference numeral 30 denotes a transfer charger for copying an image developed on the photoconductor 21 by the toner supplied from the developing device 22 described later, to the copy material in the form of paper or sheet by the transfer charger 30. Is. Reference numeral 34 denotes a corona discharger, which charges a sheet-shaped document 37 to be read on the upstream side of an unused portion of the photoconductor drum 21 rotating in the E direction. It is directly attracted and fixed by electrostatic force. Reference numeral 36 denotes a CCD sensor for reading an original, which is for reading image information of the original 37 according to a conventional method.

Incidentally, the developing device 22 shown in FIG.
2 is described with reference to the schematic explanatory view of FIG. 2, the developing device 22 includes a developing tank 23 that stores a conductive toner T as a developer, and a conductive toner T that is rotatably provided in the developing tank 23. An agitating roller 24 for agitating, a toner holder 25 disposed at a position facing the photosensitive drum 21 in the opening 23 a of the developing tank 23, and an opening 2 of the developing tank 23.
3a, a doctor blade 26 fixedly provided below the toner holder 25. The toner holder 25 extends along the width direction of the photosensitive drum 21, and has a magnetic roller 25a in which magnets of N polarity and S polarity are alternately arranged in the circumferential direction, and a non-magnetic material such as aluminum or martens. The developing sleeve 25b is made of site type stainless steel and is provided so as to cover the outer peripheral surface of the magnetic roller 25a.

The toner holding member 25 develops the conductive toner T on the developing sleeve 25 by the alternating magnetic field generated by the rotation of the magnetic roller 25a in the device in the Fa direction.
It is held on the surface b and conveyed in the direction Fb, which is the opposite direction to the direction Fa in which the magnetic roller 25a rotates. Further, the doctor blade 26 adjusts the carrying amount of the conductive toner T held on the surface of the developing sleeve 25b and carried in the Fb direction as described above to a predetermined amount. The conductive toner T is obtained by kneading a resin made of styrene-acrylic copolymer or the like with magnetic powder such as iron powder or ferrite, carbon black, etc.
It is composed of powder having a size of several μm to several tens of μm. Further, in FIG. 2, reference numeral 27 is an exposure device composed of the above-mentioned LED.

The operation of the platenless copying machine according to the embodiment of the present invention of FIG. 1 constructed as described above will be described with reference to the drawings. First, as described above, in the present invention, the unused portion of the upper portion of the photosensitive drum 21 using the transparent base material is effectively used, and therefore, the rotation direction E of the photosensitive drum 21 is The corona discharger 34 is arranged on the upstream side, whereby the original 37 is directly attracted and fixed to the charged portion of the photosensitive drum 21, and the original is read by the reading CCD sensor 36. In this case, as the original, any sheet such as paper may be used as long as it is a sheet and has a material and a shape that is attracted and fixed to the photosensitive drum by electrostatic force.

As described above, after the image information of the original 37 is read by the CCD sensor 36 for reading the original,
An exposure device configured by an LED array irradiates light in the direction of the developing device 22, thereby attracting toner and developing. In this case, the exposure control operation is performed by a printer controller (not shown), and the irradiation light is focused on the photoconductive layer through the transparent support of the photosensitive drum 21 and the transparent conductive layer. The optical scanning by the exposure device 27 is performed only by rotating the photoconductor drum 21 in the E direction because the plurality of light emitting elements are arranged in parallel along the width direction of the photoconductor drum 21. .

Next, the image thus developed is
The transfer charger 30 makes a copy on the conveyed paper or sheet-shaped copying material. Below, FIG.
The mechanism of the developing process of the conductive toner T will be described with reference to the schematic diagrams for explaining the first to third steps shown in FIG. In these figures, the photosensitive drum 21
In the above configuration, the transparent conductive layer 21b and the photoconductive layer 21c made of a photoconductive substance are sequentially laminated on the surface of the optically transparent cylindrical transparent support 21a, and both are formed.

First, as shown in FIG. 3, the conductive toner T stored in the developing layer 23 is held on the surface of the developing sleeve 25b by the alternating magnetic field generated by the rotation of the magnetic roller 25a in the Fa direction. , Developing sleeve 25
It is conveyed on the surface b in the Fb direction, which is the opposite direction to the E direction, which is the rotation direction of the photosensitive drum 21. At this time, at the contact portion between the conductive toner T held on the surface of the developing sleeve 25b and the photosensitive drum 21, the development is performed by a potential difference of several tens of V applied between the developing sleeve 25b and the transparent conductive layer 21b. Charge is injected from the sleeve 25b to the photosensitive drum 21 through the conductive toner T,
The surface of the developing sleeve 25b is charged to substantially the same potential. The conductive toner T that has come into contact with the photoconductor drum 21 as described above is the surface of the photoconductor drum 21 and the developing sleeve 25.
When b is at the same potential, the magnetic force generated by the magnetic roller 25a in FIG.

Next, as shown in FIG. 4, the photosensitive drum 2
When the light emitting elements corresponding to the image pattern are sequentially selected from the exposure device 27 of FIG. 2 to be exposed immediately before the conductive toner T and the conductive toner T are separated from each other, or at a portion G near the conductive toner T.
The charges injected into the surface of the photosensitive drum 21 are neutralized, and a potential difference is generated between the surface of the photosensitive drum 21 and the developing sleeve 25b. After that, due to the potential difference as described above, the charge is again injected from the developing sleeve 25b through the conductive toner T to the photosensitive drum 21, but before the charge is sufficiently injected, the photosensitive drum 21 and the conductive toner T are injected. As shown in FIG. 5, the conductive toner T is subjected to the action of the electric field acting between the developing sleeve 25b and the surface of the photosensitive drum 21 in the state where the electric charge is injected, so that the conductive toner T receives the magnetic force of the magnetic roller 25a. It is shaken off and adheres to the surface of the photoconductor drum 21, and is developed on the surface of the photoconductor drum 21 as a toner image according to the image pattern.

As is clear from the above embodiments, the present invention was made by paying attention to the effective use of the image forming process portion of the photoconductor surface, and the sheet original is fixed by using electrostatic force. By adsorbing and fixing it to the photoconductor by means of 1), it becomes possible to realize 1) the exclusive original platenless. 2) The drive unit for the image reading sensor is not required. 3) The optical reading optical path becomes small. 4) The original can be read in synchronization with the speed of the photoconductor, and it is easy to ensure the synchronization between reading and optical writing. 5) Due to 1) to 3), the size and cost of the digital copying machine can be reduced. Etc. are possible.

[0017]

According to the present invention, there is no need for a dedicated document table, there is no need to move the image reading sensor along with the document, and a low-cost document tableless copying machine having a compact and simplified structure is provided. It is possible to provide, and the practical effect is extremely remarkable.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a basic configuration of a document tableless copying machine of the present invention.

FIG. 2 is a schematic explanatory diagram showing a configuration of the developing device shown in FIG.

FIG. 3 is an explanatory schematic diagram of a first step showing the mechanism of the developing process in the invention.

FIG. 4 is an explanatory schematic view of a second step showing the mechanism of the developing process in the invention.

FIG. 5 is an explanatory schematic diagram of a third step showing the mechanism of the developing process in the invention.

[Explanation of symbols]

 21 Photoreceptor Drum 21a Transparent Support 21b Transparent Conductive Layer 21c Photoconductive Layer 22 Developing Device 23 Developing Tank 23a Opening 24 Stirring Roller 25 Toner Retainer 25a Magnetic Roller 25b Developing Sleeve 26 Doctor Blade 27 Exposure Device (LED Array) 30 Transfer Charger 34 Corona discharger 36 CCD sensor for document reading 37 Document

Claims (1)

[Claims] 1. A light for charging a photosensitive member using a transparent base material by bringing a charged toner stirred in a toner developing tank into contact therewith, and for optically writing from the inside to the inside of the photosensitive member. In a digital copying machine having an image forming apparatus having a writing element and an image reading sensor provided so that a document can be digitally read, a digital charging device for charging a contact surface of the photoconductor with the document is provided, and copying is performed. An original plateless copying machine, comprising means for directly adsorbing and fixing an original to be charged on the charged surface of the photoconductor by electrostatic force.