JPS59155871A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the generation of a transfer position shift, a picture failure, etc. by attracting electrostatically a transfer material to a carrying belt, and also supporting by slide-contact the carrying belt by a guide member whose face slide-contacting with the belt is an insulating face. CONSTITUTION:When a transfer paper P is fed onto a belt 2 in front of a printer mechanism I , it is attracted electrostatically to the belt 2 by a charger 59, therefore, the transfer paper P is held exactly in an exact attitude on the belt 2. Also, both end parts of the belt 2 are guided to slid contacting with a guide having a linear guide face provided so as to support the belt 2 by at least each transfer station, and as for the whole of the guide member or its guide face, an insulating resin having a good lubricating property is used. Also, guide plates 103, 104 for supporting by slide-contact a part between both ends of the belt 2 are provided before and behind a transfer device 12. In this way, the belt and the transfer material pass through a regular position, therefore, the generation of a transfer shift and a picture failure is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an image forming apparatus that forms an electrostatic latent image on an image carrier, develops this latent image, and then transfers the developed image to a transfer material that is placed on a conveyor belt and conveyed. Regarding.

In the above-mentioned image forming apparatus, simply placing the transfer material on the belt causes problems such as the posture of the transfer material becoming unstable and the image not being transferred to the correct position on the transfer material. On the other hand, even if the transfer material is securely held in a normal position on the belt, the belt may not pass through the correct position at the transfer station due to slack in the belt or vibrations during driving, and may be located at a distance υ from the image carrier. When passing through a certain position, the speed of the belt may slightly fluctuate, and the transfer material may be electrostatically attracted to the image carrier, causing the transfer material to be raised high from the bell F. Such inconveniences may occur.

The aim of the invention is to overcome the above-mentioned disadvantages.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram of one embodiment of the present invention, and is an example of an apparatus for forming a color image.

The apparatus of this example incorporates four sets of electrophotographic laser beam printer mechanisms as plural sets of image forming mechanisms. That is, 1 is the main machine box of the device, and l-l-■ and ■ are the first to fourth parts arranged sequentially from the right side to the left side in the main machine box 1 in the drawing.
The four sets of laser beam printer mechanisms (hereinafter simply referred to as printer mechanisms) 6.4 are located diagonally below and to the right of the first printer mechanism, and the fourth printer mechanism 4. A belt pressure sailor is disposed diagonally downward to the left of +4 N, and is rotationally driven in the direction of the arrow with high precision by a drive source (not shown). A transfer paper is placed on the belt drive roller 6.4, and the unprocessed screen belt 2 for conveying the transfer paper is suspended around the belt drive roller 6.4. The screen belt 2 is made of synthetic resin (for example, Tetron), etc.
The drive roller 6.4 is made of a flexible mesh, which will be described later in the direction of the arrow shown in the figure.
It moves through the transfer station of each printer (long jRI~■. 5 is the paper feed mechanism arranged on the right side of the machine frame, 6
7 is an image fixing device disposed on the left end side, and 7 is a print output outlet.

The mechanical configurations of the printer machines 4#ff1 to #4 are substantially the same. That is, each printer mechanism has a drum-type electrophotographic photoreceptor 9 (hereinafter simply referred to as a drum) as an image carrier that is rotationally driven in the direction of the arrow around a shaft 8.
, consisting of a charger 1011, a developer 11, a transfer belt iW unit 12, a cleaner 16, which are arranged in order in the drum rotation direction around the drum, and a laser beam scanner 14 arranged above the driver 9. .

The laser beam scanner 14 consists of a semiconductor laser polygon mirror #f-theta lens, a light shielding plate, etc., and receives the input of time-series electric digital pixel signals S calculated and output from an image reading device and an electronic calculator (not shown in the figure). , a blinking modulated laser beam L is oscillated in response to the signal, and the portion of the drum surface between the charger 10 and the developer 11 is scanned in the direction of the drum generatrix, thereby exposing the drum surface. This forms an electrostatic strip.

The latent image is developed by a developing device 11. However, the developing device 11 of the first printer mechanism I is loaded with yellow Y developer, the second is loaded with magenta M developer, the sixth is loaded with cyan C developer, and the fourth is loaded with cyan C developer. It accommodates black BK developer. The laser beam scanner 14 of the first printer mechanism I receives a pixel signal s (y) corresponding to the yellow component image of the color image, and the second mechanism ■ receives a signal S (M) corresponding to the magenta component image. ) is the sixth
A signal S (C) corresponding to the cyan component image is input to the 4M 4r'l III, and a signal 5 (BK) corresponding to the black component image is input to the fourth mechanism IV.

When the transfer paper P is inserted onto the paper feed guide 51 of the paper feed mechanism 5, its leading edge is detected by the first photo interrupter 52 and a start signal (print sequence start signal) is generated.
is emitted. In response to this start signal, the drums 9 of each printer machine (1) to (2) begin to rotate. The drive row 25.4 is also driven at the same time, and the screen belt 2 also begins to run.

The transfer paper P has two register rows 56 and a paper feed guide 55.
, the register row 2 pair 56, and the paper feed guide 57, and are fed onto the screen belt 2.

The transfer paper on the screen belt 2 is subjected to, for example, DC corona radiation, which has an ionic component having a polarity opposite to that of the developer, by the adsorption charger 59, and is persistently and statically adsorbed to the screen belt. Ru.

At this time, the guide 58, which serves as the opposite pole 'a' of the charger 59, is made of a conductive material and is not connected to the ground, for example.

As the belt moves, the leading edge of the transfer paper passes through the photointerrupters 60Y, 60M, and 600°6 as transfer paper detection means.When the IBK is sequentially interrupted, each of the printer mechanisms 1 to 1 corresponding to each photointerrupter receives a signal. Image formation on the drum 9 is sequentially started.

That is, the yellow version image as a color component of the color image is on the drum 9 surface of the first printer mechanism (3), the same magenta version image is on the second one, the same cyan version image is on the fifth one, and so on.
The fourth one is formed with the same thermal plate image, respectively. (The image forming principle in each printer mechanism is already well known, so its explanation will be omitted.) In this way, the signals of the transfer paper detection means disposed in front of the transfer station of each printer (reception t; By starting the individual formation using each printer machine (;, f, it becomes possible to transfer the developed image formed by each printer mechanism to the required position on the transfer paper. Images of each color can be superimposed and transferred onto the transfer paper.The transfer is performed by applying a corona discharge of opposite polarity to the developer to the back side of the transfer paper through the belt mesh by the transfer charger 12 of each printer mechanism. After the transfer paper passes through the printer mechanisms ① to ②, the static electricity is removed by the static eliminator 61 to which AC voltage is applied, and the transfer paper P is separated from the screen belt. 51a and enters the fixing device 6, where the formed color image is fixed and is ejected from the output lower to the outside of the machine as a color image print.

Note that 62 and 65 are tension rollers for applying tension to the screen, 62 is rotatable but its position is fixed, and 66 is rotatable, and
It can swing in the direction of the arrow.

As described above, the forging belt 2 is smaller than the screen size and can easily perform good transfer. Also, when the transfer paper is fed to the belt 2 in front of the printer mechanism I, the charger 5
Since the transfer paper 9 is electrostatically attracted to the belt 2, the transfer paper is reliably held in an accurate posture on the belt 2, making it possible to prevent color shift transfer. Incidentally, the step of adhering the transfer paper to the belt by the charger 59 is preferably performed at a position in front of the transfer paper detection means 60Y. This makes it possible to align the image formed on the drum and the transfer paper even more accurately. After the transfer paper passes through the printer mechanism I, it is electrostatically attracted to the belt 2 due to the charge received by the transfer charger of each printer mechanism.

Now, with the above device, as shown in Fig. 2, the screen belt 2 passes through a position 2 that is lower than the original trajectory 2', and the amount of sagging A is not constant, and the belt If the circumferential speed changes slightly, this phenomenon causes speed fluctuations in the paper being stored and fed, resulting in color misregistration. Also, the transfer paper P is transferred when passing through the transfer station; it is separated from the belt by the Rona and fixed on the photosensitive drum, and is attracted to the belt again after transfer, but when the trajectory of the belt 2 shifts from the normal trajectory 2', the transfer occurs. The trajectory of the paper at the transfer/transfer station is different for each transfer station, the reproduction is also different υ, and it also varies depending on the fluctuation of the amount of drooping υ A mentioned above, and this phenomenon causes color misregistration. . Such a situation is likely to occur when a long belt is used as in the illustrated example, but the present invention prevents such inconvenience. Figure 6 shows the first embodiment of the present invention. , both ends of the belt 2 are brought into sliding contact with stationary guides 101 and 102 for guidance. The guides 101 and 102 have linear guide surfaces (surfaces on which the belt 2 slides), and preferably pass through the transfer station of each printer mechanism from near the position where the belt 2 is separated from the row 25. Although it is preferable that the belt 2 is continuous up to the vicinity of the position where the belt 2 starts winding around the roller 4, it is preferable that at least each transfer station is provided to support the belt.

Further, it is preferable that all of the guides 101, 102 or the above-mentioned guide surfaces be made of X-type resin (trade name: Delrin, nylon, Teflon, etc.), which has good lubricity to reduce frictional resistance. Furthermore, since the resin is insulating, it is preferable in that it prevents the charge on the belt 2 for adsorbing the transfer paper from being removed and enables stable paper conveyance.In any case, the above configuration improves the prevention of color misregistration. but,
If the central portion of the belt is also supported, the stability of the belt trajectory will be further improved, and the effect of preventing color shift will be further enhanced. The example shown in FIG. 4 achieves this. In FIG. 4, plates 105 and 104 are provided at positions before and after the transfer charger 120 for slidingly supporting the portion between both ends of the bell 120. When the adsorption charge is removed, a phenomenon may occur where the transfer paper leaves the belt and is attracted to a nearby conductive object. In this case, color shift occurs, so guide 105.1'04 When a polyethylene terephthalate sheet (trade name: Mylar) is pasted on the sliding surface of belt 2, the transfer paper adheres extremely well to belt 2, and color scratches are significantly reduced. Guides 101 and 102 are abolished. Guide 103
．． -104 only may be provided.

The screen 5 shows another embodiment of the present invention, and is preferably made of a lubricating resin as a guiding guide that slides and supports the screen belt 2 over its entire surface.

Therefore, it is preferable to provide a layer of tetrafluoroethylene resin, polyethylene terephthalate, or the like on the surface of the metal plate.

In addition, the guidance guide 105 has an opening 1 for a photo interrupter.
07 and an opening 106 for the transfer zone/northern 12 must be provided.

As mentioned above, since the trajectory of the screen belt and the transfer paper is reproduced extremely accurately, the amount of color shift is extremely small.
- We were able to realize a printer.

In the embodiment, an image forming means in the form of a laser beam printer has been described, but the image forming means may be formed by optically forming a document image as in a normal copying machine.

Further, although the description has been made using image forming means for four colors, the gist of the present invention does not change even if image forming means for two to six colors are used.

It can also be applied to monochrome copiers and printers that require accurate image dimensions, such as drawings and maps.

[Brief explanation of the drawing]

FIG. M1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a belt locus, and FIGS. 3, 4, and 5 are explanatory diagrams of main parts of an embodiment of the present invention. 2 is a screen pel), 5.4 is a belt drive roller, 9
is an electrophotographic photosensitive drum, 59 is a charger, 101 to 105
is a guide. Applicant: Gyanon Co., Ltd.

Claims (1)

[Claims] In an image forming apparatus that forms an electrostatic latent image on an image carrier, develops this latent image, and then transfers the developed image to a transfer material that is placed on a conveyor belt and conveyed, the transfer material is statically placed on a conveyor belt. a charging means for electrically adsorbing; and a guide member for slidingly supporting the conveyor belt so that the conveyor belt passes through the transfer station in a constant trajectory, the guide member having at least an insulating surface for slidingly contacting the belt. An image forming apparatus comprising: