JPS584169A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To improve copying speed by properly using a system for transferring a latent image formed on a screen sensitive drum to a main drum and a system for forming a latent image by directly exposing the main drum in accordance with the number of copies to be prepared in every original. CONSTITUTION:In case of a small number of copies, a mirror 5 is set up on a position shown by a two dots-dash line and the image of an original O is directly exposed on a main drum 3 uniformly charged by a charger 10 to form a latent image. In case of a large number of copies, the mirror 5 is returned to the position shown by a full line and the image of the original is exposed on a screen sensitive drum 2 uniformly charged by a charger 6. By irradiating ions from a charger 9 to the main drum 3, the latent image on the screen sensitive drum 2 is transferred to the main drum and the required number of copies can be obtained without repeating said image exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying machine, and an object thereof is to speed up copying as much as possible.

Conventional general electrophotographic copying machines not only perform single copying but also multi-copying in order to obtain the desired number of copies by repeating one copying cycle using the same series of image forming processes as in single copying. It has become.

Therefore, the time it takes to make copies of all the desired number of copies is the same as the entire image forming process, excluding the preparation time before starting copying (e.g., warming up time for the copier, time for setting paper and originals, etc.). This is the total cycle time for the total number of copies.

- The shorter the copying cycle time, the faster copying will take place.

Regarding this point, the 3#l existing copying machine has a mechanical design innovation 9.
By improving the accuracy and quality of parts, etc., the speed of driving the minimum number of devices without causing problems such as deterioration of image quality and vibration of the device can be speeded up as much as possible to shorten one copying cycle time as much as possible. This will dramatically increase the speed of equipment drive compared to current IA technology.

In other words, it is currently difficult to expect much reduction in one copy cycle time.

On the other hand, some of the above-mentioned general copying machines are capable of high-speed copying and are capable of copying using a secondary latent image forming method.

For example, a static electricity residue image is once formed on a mesh screen photoreceptor. After that, a secondary latent image is formed on the insulator surface by modulating the ion flow using the latent image on the photoconductor as a master → development of the secondary latent image → transfer of the developed image to the transfer material surface → transfer image By repeating the fixing process, a desired number of copies can be obtained.

That is, the document am light process for the photoreceptor, which is the biggest obstacle to speeding up the device drive, is 11! when the first master latent image is formed. ! J only, then each copying cycle is performed without a full length exposure step.

After the master latent image has been formed, the photoreceptor is no longer limited in driving speed due to the relationship with the original image exposure process and can be driven at high speed, greatly shortening the time for each copying cycle. It is also capable of high-speed copying, and the larger the number of copies, the more advantageous it is in terms of time compared to general copying machines.

However, since the process of forming a master latent image on the photoreceptor is added to the first copy, there is a drawback that the time from the start of copying until the first copy is obtained is longer than in the case of a general copying machine.

Therefore, in general, in the case of single copying or multi-copying of a small number of sheets of 5 am, a general copying machine is more advantageous in terms of time, and in the case of multi-copying of many more sheets, it is more advantageous in terms of time.
It can be said that a copying machine using a secondary latent image forming method is more advantageous.

In view of the above, the present invention has been devised to combine the advantages of the above-mentioned introspection, and to enable time-efficient copying whether it is a single copy, a small number of copies, or a large number of copies. The purpose is to provide a copying machine with the following features.

That is, a first photoreceptor, a second photoreceptor, a common document image path light means for both of the photoreceptors, and a document image path light means from the document image side light means are transferred to the first photoreceptor side or the other side. A light exposure switching means for selectively switching to the second photoreceptor side, and means for forming an electrostatic latent image corresponding to the original light image exposed to the photoreceptor on the first photoreceptor surface.

means for forming an electrostatic charge ** corresponding to a document optical image edited on the photoreceptor on the surface of the second photoreceptor;
A means for developing *, a means for transferring the developed image g16 onto a transfer material, and a secondary latent image is formed on a second photoreceptor surface by using the latent image formed on the first photoreceptor surface as a master latent image I image. and means for switching the optical path switching means to the first photoconductor to apply an electrostatic fl! corresponding to the document optical image to the surface of the photoconductor. Form an image.

Thereafter, the steps of forming a secondary latent image on the surface of the second photoreceptor using that ** as a master latent image, developing that latent image, and transferring the developed image to a transfer material are repeated to form a single image. For multi-copying of a small number of copies or less than a predetermined number of copies, the original optical image switching means is switched to the second photoconductor side, and an electrostatic latent image corresponding to the original optical image is formed on the surface of the photoconductor;
The process of developing the latent image and transferring it onto the transfer material.

Alternatively, the above steps may be repeated. A detailed explanation will be given based on an embodiment of an electrophotographic copying machine having the following features.

The copying machine shown in the first diagram forms an image using the so-called NP process disclosed in Japanese Patent Publication No. 42-2!1910 and Japanese Patent Publication No. 43-24748. are two drum-shaped photoreceptors, first and second photoreceptors, which are arranged in parallel and close to each other in the machine box, and are driven to rotate in the arrow direction about shafts 21 and 61, respectively.

The first drum photoreceptor 2 is of a mesh screen type, and as shown in FIG.
1. A photoconductive layer 22 formed by extending the periphery of the mesh lines of the mesh substrate. The basic constituent layer is an electrically insulating layer 2606M formed by applying wax around the photoconductive layer, and a large number of small holes 24 corresponding to the mesh of the base 21 are present on the surface of the drum.

The second drum photoreceptor 6 does not have such small holes and has a conductive substrate 31. as shown in the second figure. Photoconductive layer 62.
The electrically insulating layer 3603 is the basic constituent layer.

Reference numeral 4 denotes a common original document light means for both the light bodies 2 and 3, which includes a document mounting table 41 made of a transparent plate such as a fixed gas plate fitted into a window hole made in the top plate 11 of the machine case 1; , the document illumination lamp 42 and the movable first mirror 43 move toward the left side of the table along the bottom surface of the table at a speed of V, with the table cloth side as the home position, and the moving first mirror 43 moves to the bottom side of the document table at a speed of v72. It consists of movable second and sixth mirrors 44 and 45 that move forward, an imaging lens 46, and a fixed mirror 47.

Reference numeral 5 denotes a mirror that swings around a shaft 51 disposed between the fixed mirror 47 and the second photoreceptor 30 as an optical path switching means.
The vertical 11th beam shown by the solid line intervenes in the optical path between the photoreceptors 6 of
The selection is switched between 1 & 2 and the 2nd document 0 shown by the two-dot chain line which has escaped from the optical path. The document 0 is placed on the document table 41 with the image side facing down, and the document suppressing plate 48 is placed on top of it. Set by covering. The original illumination lamp 42 is turned on in response to the copy start signal, and the lamp 42 and the first movable electric lamp 43 move forward together at a speed of V.

The moving second and third mirrors 44 and 45 move forward at a speed of V/2, and the image surface of the original O is sequentially optically scanned from the right side to the left side. And the original scanning light is mi'')-46→
44 → 45 → lens 46 → ζ2 47, and when the optical path switching mirror 5 is in the first attitude shown by the solid line, it is reflected by the mirror 5 and enters the exposure section of the first photoreceptor 20;
When the optical path switching mirror 5 is switched to the second attitude of the escape position shown by the two-dot chain line, the light enters the exposed portion of the second photoreceptor 6.

Reference numerals 6, 7, and 8 indicate a primary charger and a secondary Teiden device, which are used as electrostatic latent image forming means for the first photoreceptor 2 and are disposed facing the photoreceptor in sequence in the rotational direction of the photoreceptor.

It is a full-surface exposure device. The secondary charger 7 is a light transmission type.

The original light image is positioned at the ninth portion of the photoreceptor 2.

Reference numeral 9 denotes a modulation charger as a means for forming a secondary 1W image on the 3 surface of the second photoreceptor by using the electrostatic latent image formed on the 2 surfaces of the first photoreceptor as a master latent image.

A discharge opening is disposed in the first photoreceptor 2 at a portion where the first and second photoreceptors 2 and 3 face each other, with a discharge opening facing toward the opposite portion of the photoreceptors 2 and 6.

Reference numerals 10 to 14 are image forming process devices arranged sequentially in the rotational direction around the photoreceptor 3 for the second photoreceptor 3, and in the A body, 10, 11, and 8 are electrostatic Ia forming means. They are a primary charger, a secondary charger, and a full-surface exposure device. The secondary charger 11 is a light IIa type and is located at the original light exposure section relative to the isthmus light body 6. In addition, the entire surface exposure S8 is performed on the first photoreceptor 2.
O12, which has the same structure as the current V device, and 13, a transfer charger.

14 is a cleaning device 015 paper cassette 1
51 A paper feeding mechanism section consisting of a paper feeding roller 152, a timing roller 1F43, etc., 16 a conveying device that conveys the transfer material that has passed through the transfer section 13 and is separated from the photoreceptor surface to a fixing device [17], and 18 an external device. Indicates a tray that receives copies ejected to.

(1) Multi-IiL photoconductor 2, photoconductor 2, photoconductor 2, photoconductor 2, photoconductor 2, photoconductor 2, photoconductor 2, photoconductor 5, both 1m and copying was carried out using the printing method.

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In the graph in Figure 4 of J416e, lines (1) and (2) are defined as (2) when the number of copies is 5 or less.
) In the case of (1), in other words, it is more advantageous in terms of time to perform copying using the simple edge of the NP process, and on the other hand, in the case of (1), that is, copying using the secondary copying method. It turns out that it is more advantageous to do so.

Regarding the relationship between lines (1) and (2), the same thing as above can be said when the number of copies is three.

Therefore, if the reference number N in the above-mentioned discrimination circuit 52 (FIG. 5) related to the number of copies setter is set to 5 or 6, for example, and the set number of copies N is larger than that, the above-mentioned (1) ), and in cases where the number is smaller than that (including single copy), N in (2) is used.
By switching and controlling the copying method so that copying is executed using the P process repetition method, it is possible to save time in both single copying, multi-copying with a small number of sheets, and multi-copying with many sheets. It is possible to achieve advantageous copying, and the desired purpose is well achieved.0 Note that the latent image forming process on the first and second photoreceptors 2 and 3 is not limited to the illustrated NP process;
Other suitable latent image formation processes may be employed. The document exposure means may be of a type that moves the document table. The means for forming the secondary latent image is not limited to the mesh screen method, but may also be a transfer method in which the latent image is brought into contact with an object.

In the case of (1) secondary acid image forming method copying, (2) NP
Since the developing device 12 and the developer transfer charger 16 are shared even in the case of nine repeated copying processes, the polarity of the secondary latent image formed on the second photoreceptor 3 by the first photoreceptor 2 in case (1) In the case of (2), the polarity of the latent image formed on the third surface of the second photoreceptor is 0, that is, in the case of (1), #! The dark part polarity of the latent image formed on the photoreceptor 2 of
The polarity of the dark area to be formed on the photoreceptor 6 is opposite to that of the dark area.

If the polarity is reversed, a method using a developing device with a different polarity, a non-contact desktop imaging method, etc. may be used.

In addition, in the secondary latent image forming method (1), the second photoreceptor 3
If the photoconductor has a 2M structure consisting of a substrate and a photoconductive layer, such as a xerographic photoconductor, there is no need to use a charger for static elimination to bring the surface potential of the photoconductor surface to Ov before the formation of a secondary latent layer. This can be done only by irradiating the entire surface with light.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view showing the overall configuration of the embodiment device;
The figure is an enlarged sectional view of the secondary mm forming part, FIG. 3 is a flowchart of copying method selection, and FIG. 4 is a graph of the relationship between the number of copies and copying time for each copying method. 2 and 3 are the first and second photoreceptors, 5 is a mirror for switching the output direction, and 9 is a charger for modulation. 4th page, 3rd page, 2nd figure

Claims (3)

[Claims] (1) A first photoreceptor. and a second photoreceptor. and a common original image exposure means for both of the photoreceptors. and an optical path switching means for selectively switching the original light image from the original image exposure means to the first photoconductor and the second photoconductor. means for forming an electrostatic charge ms on the surface of the first photoreceptor corresponding to the optical image of the document exposed to the photoreceptor; means for forming an electrostatic latent image on the surface of the second photoreceptor corresponding to the nine original light images exposed to the photoreceptor; and means for developing the latent image on the second photoreceptor surface. A means for transferring the developed image to a transfer material. and a means for forming a secondary image on the second photoreceptor surface in accordance with the latent image formed on the first photoreceptor surface, the multi-copy original light image optical path switching for a predetermined number or more. The means is switched to the first photoreceptor side to form an electrostatic latent image corresponding to the original optical image on the surface of the cough photoreceptor, and from then on, this latent image is used as a master latent image for secondary latent image to the second photoreceptor surface. This is carried out by repeating the steps of forming the latent image, developing the latent image, and transferring the current image to the transfer material. For single copying or multi-copying of a small number of sheets below a predetermined number, the original optical image switching means is switched to the second photoreceptor side, and a nine-electronic latent image is formed in correspondence with the original optical image on the photoreceptor.
That f#! This is carried out by transferring the combed image of Ken to a transfer material, or by repeating the process. An electrophotographic copying machine characterized by: (2) Electrostatic charge f formed on the first photoreceptor and the second photoreceptor
l! Make the polarity of the images different. An electrophotographic copying machine according to claim (1), characterized in that: (3) Compare the set number of copies with nine predetermined reference numbers, and if the number is greater than the reference number, the original light image from the original image exposure means is transferred to the first photoreceptor side, and if it is less than the reference number, the original light image is transferred to the second photoreceptor side. The exposure switching means is automatically controlled to switch to the exposure mode. An electrophotographic copying machine according to claim (1), characterized in that: