JPH04296877A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device which can increase copying speed when a copying paper of a small size is selected. CONSTITUTION:An image forming device is equipped with a first copying means 16 for superposition-copying an image having each color component onto a photosensitive body 8 and a copying belt 15 which is oppositely arranged and a second copying means 23 and 24 for copying the superposed image which is superposition-copied on the copying belt 15, to a copying paper, and the image which is determined according to the relation between the peripheral length of the copying belt 15 and the size of a selected copying paper is formed on the copying belt 15.

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, and more particularly to an image forming apparatus which has a transfer belt (intermediate transfer belt) and is capable of superimposing and transferring images of respective color components.

0002

[Prior Art] Image reading means separates and reads a color document, and each color component image obtained by charging, exposing, and developing a photoreceptor for each color component is transferred onto a transfer belt placed opposite the photoreceptor. Various types of image forming apparatuses have already been proposed, each of which has a first transfer device that performs superimposed transfer and a second transfer device that transfers the superimposed images transferred onto a transfer belt onto a transfer sheet.

0003

[Problems to be Solved by the Invention] However, in conventional image forming apparatuses of this type, one image is formed on the circumference of the transfer belt, so the copying speed is not constant regardless of the size of the transfer paper. It was hot. Therefore, when the size of the selected transfer paper is small, there is a problem that the copying speed becomes relatively slow.

[0004] The present invention eliminates the drawbacks of the above-mentioned prior art,
An object of the present invention is to provide an image forming apparatus that can increase copying speed when a small size transfer paper is selected.

[0005]

[Means for Solving the Problems] The above object is to provide an image reading means for color-separating and reading a color original, and a photoreceptor for each color component image obtained by charging, exposing, and developing each color component on the photoreceptor. In an image forming apparatus, the image forming apparatus includes a first transfer unit that transfers the superimposed image onto a transfer belt disposed facing each other, and a second transfer unit that transfers the superimposed image transferred onto the transfer belt onto a transfer paper. After forming a number of color component images on the transfer belt by the first transfer means, the number of which is determined by the relationship between the circumference of the image and the size of the selected transfer paper, the superimposed images are placed on the transfer paper. This is achieved by providing a control means for controlling the transfer.

[0006]

[Operation] The maximum allowable number of images determined from the relationship between the transfer paper size and the circumference of the transfer belt is formed on the transfer belt, and the images are transferred to the same number of transfer papers as the number of images during one rotation of the transfer belt. and execute the copy.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention, and this image forming apparatus is composed of an image reading means, a writing means, a developing means, a fixing means, a paper feeding means, and a transfer paper conveying means. be done. The image reading means includes a contact glass 1 on which the original D is placed, an illumination lamp 2 for illuminating the original D, a first mirror 3 that moves integrally with the illumination lamp 2 in the scanning direction, and is interlocked with the first mirror 3. second and third mirrors 4 and 5 that move in the same scanning direction, an imaging lens 6 that forms a reflected light image of the original, a color image sensor 7 that is placed at the imaging position and reads and photoelectrically converts images for each pixel, and the like. Consists of.

In the above configuration, when the original D is illuminated and scanned, the original image is color-separated pixel by pixel by the color image sensor 7, and then converted into digital signals. The means for writing onto the photoconductor 8 is composed of an LD (laser diode) 9, a rotating polygon mirror 10, an imaging optical system 11 including an fθ lens, and a mirror 12, and drives the LD 9 for each color with digitized document information. The LD 9 converts it into an electric current, which outputs a light output that substantially matches the original image density, and the rotating polygon mirror 1
0, optical writing is performed on the photoreceptor 8 via the imaging optical system 11 and mirror 12. In this case, a color image is written as a normal image, and a black and white image is written as a mirror image in accordance with scanning for each color. Note that by temporarily storing the writing order on the photoreceptor 8 in a buffer (not a frame memory) (not shown) and changing it, it is also possible to write on the photoreceptor 8 as a normal image or a mirror image. The latent image written on the photoreceptor 8 by the writing means is visualized as a toner image by the developing means 13. The developing means 13 consists of four developing devices housed in four partitioned areas within the rotating cylinder 14, and these four developing devices include a developing device 13Y for developing yellow toner and a developing device 13Y for developing magenta toner. Developer 13M
, a developer 13C for developing cyan toner, and a developer 13B for developing black toner. When a latent image of a color to be visualized arrives in each of these developing devices, the developing device containing toner of that color stops at a position facing the photoreceptor 8, and development is performed. The latent image previously formed on the photoreceptor 8 is, of course, a mirror image for a monochrome original, and a normal image for a color original.

Next, the normal color toner image is transferred to an intermediate transfer belt 15 facing the photoreceptor 8 by a charger 1.
Transcribed by 6. This operation is repeated for each color to form a color image on the intermediate transfer belt 15. At this time, the transfer paper stored on the cassette 17 (or 18) is sequentially fed from the top by the paper feed roller 19 (or 20), and sent out to the registration roller 22 by the feed roller 21. I'll wait here. Next, in order to align the beginning of the black toner image on the photoreceptor 8 or the color toner image on the intermediate transfer belt 15 with the beginning of the transfer paper,
The registration rollers 22 are driven, and the black toner image on the photoconductor 8 is transferred onto the transfer paper by the charger 16, or the color toner image on the intermediate transfer belt 15 is transferred to the transfer paper by the chargers 23 and 24. Finally, the transfer paper on the intermediate transfer belt 15 is separated by the charger 25 and conveyed to the fixing means.

The fixing means includes fixing rollers 26 arranged opposite to each other.
, 27, and the unfixed toner image on the transfer paper separated from the intermediate transfer belt 15 is transferred to these fixing rollers 26.
, 27 and then fixed. After passing through the fixing means, the transfer paper is changed its course by the first switching claw 28. first,
At the solid line position, the transfer paper is discharged to the paper discharge tray 30 via the paper discharge rollers 29. Next, at the broken line position, the transfer paper is once conveyed downward. The second switching pawl 35 is at the solid line position at this time, and after the trailing edge of the transfer paper passes the paper detection element 36, the conveyance rollers 31 to 34 are temporarily stopped, and the first switching pawl 28 returns to the solid line position, then reverses. As a result, the transfer paper is reversely discharged onto a paper discharge tray by a paper discharge roller 29. Next, when the first switching claw 28 is at the broken line position, after the trailing edge of the transfer paper passes the paper detection element 37, the second switching claw 35 is changed to the broken line position, and the conveying rollers 31 to 34 are temporarily stopped and then rotated in reverse. By doing so, the transfer sheets are stacked on the intermediate tray 38, which is intermediate stacking means. Thereafter, the transfer paper is conveyed to the registration rollers 22 by the paper refeed roller 39 in response to another copy command. The transfer paper conveying means is configured in this manner.

Finally, the photoreceptor 8 and the intermediate transfer belt 1
The incidental means on the fifth lap will be explained. The charger 40 is a charger for lowering the potential of the photoreceptor 8 under the toner image, and has the effect of increasing the transfer efficiency of the toner image. The charger 41 lowers the potential of the photoreceptor 8 under the residual toner after transfer, and acts so that the cleaning means 42 removes all of this residual toner from the photoreceptor 8. The static elimination lamp 43 is a lamp for erasing the residual potential on the photoreceptor 8, and the charger 44 is a means for charging the photoreceptor 8. The dustproof glass 45 prevents the writing means from being soiled by toner, paper dust, etc. around the photoreceptor 8. The charger 46 is a static eliminating charge for changing the polarity of the surface of the intermediate transfer belt 15, and the charger 47 is a static eliminating charge for changing the polarity after cleaning. The cleaning means 48 is the intermediate transfer belt 1
When the toner image is held on the intermediate transfer belt 15 by the cleaning means for removing residual toner after transfer on the intermediate transfer belt 15, the cleaning means is released.

Next, an embodiment of the image data processing block of the image forming apparatus according to the present invention will be described with reference to FIG. This image data processing block consists of an image reading section, an image processing section, an image writing section, and a storage section. Image reading section 1
00, the CCD (imaging device) 102 photoelectrically converts original image data. The CCD driving section 101 drives the CCD 102 according to the resolution (dots/mm). CCD1
Each color component (R, G,
B) is amplification, dark current correction, and
Shading correction and A/D conversion are performed. The A/D converted image data is subjected to correction of positional deviation of each color component of the reading line in the digital processing unit 104. In this way, each color component signal is sent to the image processing section without positional deviation. In the image processing section 105, the image processing unit 10
6 performs color processing (RGB→YMC, etc.), magnification processing, and other processing. Here, it can be determined whether the document D is a monochrome document or a color document, and the image data converted into Y, M, C, and B is sent to the writing section 108. A clock generating section 107 generates a basic image frequency and transfers it to the CCD driving section 101. In the writing unit 108, the writing control unit 109
Performs writing speed correction, writing position deviation correction, etc. The LD drive unit 110 converts a digital signal indicating image density into an LD drive current (PWM, power modulation), and drives the LD1.
11 (LD9 in FIG. 2).

Next, the overall electrical configuration of the image forming apparatus according to the present invention will be explained using the block shown in FIG. The fixing heater 120 is a roller heating heater built into each of the fixing rollers 26 and 27 (FIG. 2). The system controller (control means) 121 includes a main control section and a key input control section (not shown) in the operation section. The input various copy modes are processed by the key input control section, and the data is output to the image processing section 105. Image processing unit 105
performs processing such as changing magnification based on input data. Furthermore, the input copy mode is controlled by the motor control unit 1 through the main control unit.
22, data is output to the process control unit 123 and the like. The motor control unit 122 controls various motors (scanner, conveyor, developer, intermediate transfer belt, etc.) by predetermined operations. The process control unit 123 controls on/off and output values of illumination lamps, high-voltage power supplies, and the like. Various sensors 124 detect the presence or absence of transfer paper and the fixing roller 26.
, 27 surface temperature sensing elements, and the output values are input to the system controller 121. Also, other D
The C load 125 consists of an electromagnetic clutch such as a paper feed roller, an electromagnetic solenoid such as a switching pawl, etc., and its operation is controlled by a main control section within the system controller 121. Option 126 consists of an automatic document feeder and the like. A DC power supply 127 supplies power to various loads.

Next, the image forming mode will be explained based on FIGS. 4 to 7. FIG. 4 is an explanatory diagram of an image forming mode for a normal monochrome original. The mirror latent image formed on the photoreceptor 8 is visualized in the black developing section 13B and then transferred onto the surface of the transfer paper P. FIG. 5 is an explanatory diagram of the image forming mode for a normal color document. After the positive latent images formed for each color component on the photoreceptor 8 are developed by the respective color developing sections 13, they are transferred to the intermediate transfer belt 1.
5, and finally transferred to the back surface of the transfer paper P.

Next, a copying operation in the combination or duplex mode according to an embodiment of the present invention will be described. FIG. 6 is an explanatory diagram of the copy mode when combining images, and FIG. 7 is an explanatory diagram of the copy mode when duplexing images are used. Both examples are examples in which images for two sheets of transfer paper are formed on the intermediate transfer belt 15. In the composite or double-sided copy mode, a constant N determined by the following formula (1) from the feeding direction size l1 of the selected transfer paper P, the predetermined transfer paper interval l2, and the circumferential length L of the intermediate transfer belt 15 is determined for each transfer paper. P is stored in a main control section (not shown) in the system controller 121 of FIG. L≧N・l1 +(N-1)・l2 +l0
(1) However, l0 is the distance from the writing position to the first transfer position. Next, the maximum allowable number of sheets n is compared with N in equation (1), and when the condition n≦N is satisfied, combination or double-sided copying is performed in the copy mode shown in FIGS. 6 and 7. In this copying mode, first, a normal latent image for n first original images is formed on the photoreceptor 8, and then visualized by the developing means 13. Next, the first transfer means 16 transfers the toner image onto the intermediate transfer belt 15, and then the copying of the first original is completed. Next, when copying the second original, in the composite mode, after forming an image in the same manner as the first original, the image is superimposed on the first original transferred image on the intermediate transfer belt 15, and then the second original is transferred onto the back side of the transfer paper. By transferring by means 23, a composite copy is obtained. Next, in the double-sided mode, the image of the second document is read from a direction different from that of the first document, a mirror latent image is formed on the photoconductor 8, and after being visualized by the developing means 13, the toner on the photoconductor 8 is The image is transferred to the front surface of the transfer paper by the first transfer means 16, and the toner image on the intermediate transfer belt 15 is transferred to the back surface of the transfer paper by the second transfer means 23, thereby obtaining a double-sided copy.

FIG. 8 is a flowchart of image formation control on an intermediate transfer belt according to an embodiment of the present invention. The maximum number n of images that can be formed on the intermediate transfer belt 15 based on the selected transfer paper size and the circumferential length of the intermediate transfer belt 15
(S1), starts the intermediate transfer belt 15 from the reference position (S2), copies the same document in the same copy mode (S3), and stops after the intermediate transfer belt 15 has made one revolution. (S4, S5).

[0017]

[Effects of the Invention] As explained above, according to the present invention,
When forming images on a transfer belt, by forming a maximum allowable number of images that differs depending on the transfer paper size, the copying speed of small-sized transfer paper is increased and the copying productivity of small-sized transfer paper is increased. Can be done.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a configuration diagram of an image forming apparatus.

FIG. 3 is a diagram showing an example of an image data processing block.

FIG. 4 is an explanatory diagram of a copying process operation according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of copying process operation according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a copying process operation according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram of a copying process operation according to an embodiment of the present invention.

FIG. 8 is a flowchart of image formation control on an intermediate transfer belt according to an embodiment of the present invention.

[Explanation of symbols]

8 Photoreceptor 15 Intermediate transfer belt

Claims (1)

[Claims] 1. An image reading means for color-separating and reading a color original; and an image reading means for color-separating and reading a color original, and each color component image obtained by charging, exposing, and developing a photoreceptor for each color component onto a transfer belt disposed opposite to the photoreceptor. In an image forming apparatus having a first transfer means for overlapping transfer and a second transfer means for transferring overlapping images transferred onto a transfer belt onto transfer paper, the circumferential length of the transfer belt and the selected transfer A control means for controlling the transfer belt to transfer a superimposed image onto the transfer paper after forming a number of each color component image on the transfer belt by the first transfer means depending on the relationship with the size of the paper. An image forming apparatus comprising: