JP2614736B2 - Multicolor image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus, and more particularly, to a sequence control for forming a multicolor toner image on an image forming body and transferring the image to a transfer material. And a multicolor image forming apparatus having the same.

[Background of the Invention]

The present inventors have disclosed a multicolor image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 60-7585.
0, 60-76766, 60-95456, 60-95458, and 60-158475.

The multicolor image forming apparatus related to such a proposal usually employs a method of exposing and developing one single color image every one rotation cycle of a drum-shaped or endless belt-shaped image forming body. In a device that obtains a multicolor image by combining four single-color images of magenta, cyan, and black, a four-color toner image is superimposed on the image forming body by four rotations of the image forming body, and these are transferred all at once. The image is transferred to the top to obtain one color copy.

[Problems to be solved by the invention]

Therefore, when a multi-color image forming apparatus attempts to obtain a large number of color copies from the same original, it takes a very long time, and the efficiency is extremely low as compared with a single-color image forming apparatus.

If the document size is sufficiently smaller than the length of the drum outer periphery of the image forming body to compensate for this point, two or more toner images of the same color are continuously exposed and developed during one rotation of the image forming body. A method of forming a color copy by forming two or more toner images on an image forming body by one image forming cycle by using the method has been considered.

However, in this method, the interval between the multicolor toner images formed on the peripheral surface of the drum becomes extremely narrow. Therefore, the transfer of the toner image to the first transfer material is normally performed, but the toner image is conveyed to the second and subsequent sheets. It is difficult to match the transfer timing of the transfer material.

That is, the transfer material must be conveyed in synchronization with the toner image on the rotating image forming drum, and the toner image must be transferred onto the transfer material at the transfer unit. The document must be conveyed to the standby position with a margin in advance, and its operation overlaps with the preceding transfer material conveyance time, so it is not possible to take time to set the timing. The size is limited to an extremely small size as compared with the outer periphery, and thus lacks practicality.

As a result of solving this problem and improving the present invention, it is possible to obtain two or more color copies in one image forming cycle on the premise that the transfer timing of the transfer material can be set. It is an object of the present invention to provide a multi-color image forming apparatus capable of increasing the processing speed.

[Means for solving the problem]

A rotatable image forming body, charging means for uniformly charging the surface of the image forming body, a latent image forming means for forming a latent image on the image forming body, and a plurality of developing devices containing toners of different colors Means, transfer means for transferring the toner image from the image forming body to the transfer material, first feeding means for feeding the transfer material to a predetermined standby position, and feeding the transfer material from the standby position to the transfer means A multi-color image forming apparatus comprising
A control unit having a program for identifying a document and automatically selecting a different image forming sequence depending on the size of the document or the size of the selected transfer material, and performing the charging, the latent image formation, and the development a plurality of times. Repeatedly forming a plurality of multicolor toner images at different positions on the image forming body by rotating the image forming body a plurality of times, and then adding one of the plurality of multicolor toner images per rotation of the image forming body; A control unit for controlling the driving of the second feeding unit in synchronization with the multicolor toner image on the image forming body so as to obtain a plurality of multicolor images by transferring the multicolor images to the transfer material one by one. And a multicolor image forming apparatus.

〔Example〕

 An embodiment of the present invention is shown in FIGS.

The first is a block diagram showing the outline of the multicolor image forming apparatus, in which 1 is a drum-shaped image forming body having a photoconductive photoreceptor surface layer such as Se and rotating in the direction of the arrow, and 2 is an image forming body 1. A charging unit for uniformly charging the surface of the image forming apparatus; 3 an image exposure unit having a built-in laser scanner as a latent image forming unit; and 4 to 7 developing units, ie, toners of different colors such as yellow, magenta, cyan and black. Developing device which is used as a developing device and which develops by applying an AC bias while facing the image forming body in a non-contact state, 8 is a transferring device as a transferring means, 9 is a separating device, and 10 is a transferring device. A cleaning device for cleaning the residual toner of the image forming body 1, wherein the cleaning blade 10
A is kept at a position separated from the surface of the image forming body 1 when the toner image is formed on the image forming body 1.

Reference numerals 11 and 12 denote first and second paper feed rollers as first and second paper feed units, respectively. Reference numeral 13 denotes a paper feed cassette in which transfer materials are accumulated and stored. Paper roller
The transfer material carried out of the paper cassette 13 by the
A second unit that waits once at the position of the paper feed roller 12 and rotates in synchronization with the rotation cycle of the multicolor toner image on the image forming body 1
The paper is fed to the transfer device 8 by the paper feed roller 12.

Reference numeral 14 denotes a fixing device for fixing the multicolor toner image transferred to the transfer material, and reference numeral 15 denotes a paper discharge tray on which the transfer material discharged from the fixing device 14 is accumulated.

When the multi-color image forming apparatus attempts to obtain a large number of copies from the same original, the multi-color image forming apparatus identifies the original placed on the original platen and changes the image formation depending on its size or the size of the selected transfer material. If the original size is smaller than the specified size, the image exposure unit 3 and the developing units 4
7 to form two same-color or different multicolor toner images on the surface of the image forming body 1 during one rotation of the image forming body 1 as shown in FIG. 8, separator 9, first and second paper feed rollers 1
It has a function to control the operation timing of 1, 12 by a preset program.

Hereinafter, an example of an operation and an operation sequence of each of the above-described devices by the image forming program of the present invention will be described.

FIG. 3 and FIG. 4 are time charts of each program with time lapse on the horizontal axis, where Y, M, C, and BK are abbreviations of yellow, magenta, cyan, and black color images, respectively.
1Y, 2Y, and the like represent the first yellow image exposure, the second yellow image exposure, and the like.

In the first example of the program shown in FIG. 3, exposure and development of two images of the same color are continuously performed on the surface of the image forming body 1 for each rotation, and the image forming body 1 is rotated by four rotations. The obtained multicolor toner image is divided into two times, and 4
In the latter half of the cycle, the sheet is synchronously fed to perform transfer and separation, and for the second transfer material, the sheet is synchronously fed in the first half of the sixth cycle to perform transfer and separation. This is an example.

By copying according to such a sequence,
There is an interval equal to or longer than the length of two transfer materials and a time interval corresponding to the interval between the end of the first transfer material being conveyed and the front end of the second transfer material.

After the feeding of the first transfer material by the second paper feed roller 12 is completed in the sequence and the second paper feed roller 12 is stopped,
The first sheet supply roller 11 starts rotating, conveys the second sheet of transfer material, and operates so that the leading end of the second sheet of transfer material is positioned at the stopped position of the second sheet supply roller 12 and stands by. However, since there is some time to wait at the standby position for sufficient synchronization for the second transfer material, the toner on the image forming body is also required for the second transfer material subsequent to the first transfer material. The image is transferred in synchronization with the image.

In the above process, the image formation of the next original can be performed in the same manner from the fifth rotation of the image forming body 1 or the third and fourth copies of the same original can be started. The next two copies can be obtained without prolonging the processing time.

On the other hand, the second program example shown in FIG.
The surface of the image forming body 1 is exposed and developed with one or two images of different colors each time the multi-color toner image is obtained by six rotations of the image forming body 1. This is an example in which transfer and separation are performed in the second half of the cycle and in the first half of the sixth cycle for the second transfer material.

Therefore, also in this example, the interval between the operation timings of the first paper feed roller 11 and the second paper feed roller 12 can be a time difference equal to or more than one rotation of the image forming body 1, and the operation timing can be adjusted sufficiently as in the previous example. It is.

In this case as well, the next image formation for the next original or the same original can be started from the fifth rotation of the image forming body 1, so the processing time of the process required to obtain the next two copies Is not different from the precedent.

Note that the present invention is not limited to a method in which two or more images are always formed and transferred on the surface of the image forming body as described above. By detecting the document size,
The above-mentioned program is canceled and the mode of the normal image forming process is automatically selected, and an image can be formed one by one on the surface of the image forming body like a general multi-color image forming apparatus. And is included in the present invention.

〔The invention's effect〕

According to the present invention, when a large number of copies are continuously made with a document of a specified size or less, it is possible to automatically increase the copy speed and increase the processing capacity, and as a result, a large number of documents of various sizes Thus, a multi-color image forming apparatus which is very useful for general office work with a large number of handling operations and has high work efficiency has been provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a multicolor image forming apparatus, FIG. 2 is a main part view, and FIGS. 3 and 4 are time charts showing an image forming process of the apparatus. DESCRIPTION OF SYMBOLS 1 ... Image forming body 2 ... Charging device 3 ... Image exposure part 4,5,6,7 ... Developing device 8 ... Transfer device 9 ... Separator 11 ... First paper feed roller 12 ... 2 paper feed roller

Continuation of front page (56) References JP-A-61-223856 (JP, A) JP-A-59-121349 (JP, A) JP-A-60-185967 (JP, A) JP-A-60-57357 (JP) JP-A-60-17456 (JP, A) JP-B-61-1671 (JP, B2) JP-B-61-19987 (JP, B2)

Claims (1)

(57) [Claims] A rotatable image forming member; charging means for uniformly charging the surface of the image forming member; latent image forming means for forming a latent image on the image forming member; A plurality of developing means for housing, a transfer means for transferring the toner image from the image forming body to the transfer material, a first feeding means for feeding the transfer material to a predetermined standby position, and the transfer means from the standby position to the transfer means In a multicolor image forming apparatus including a second feeding means for feeding a transfer material, an original is identified, and a different image forming sequence is automatically performed depending on its size or the size of the selected transfer material. A control unit having a selectable program, wherein the charging, the latent image formation, and the development are repeated a plurality of times, and the plurality of multicolor toner images are provided at different positions on the image forming body by rotating the image forming body a plurality of times. After forming the image, per rotation of the image forming body Driving the second feeding means in synchronization with the multicolor toner image on the image forming body so as to transfer the plurality of multicolor toner images one by one to a transfer material to obtain a plurality of multicolor images; A multi-color image forming apparatus, comprising: a control unit that controls the image forming apparatus.