JPS59160159A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To prevent formation of an image in the part projecting from recording paper on the surface of an image forming body by providing a means for detecting the passage of the rear end of the recording paper in the position on a route where the recording paper is fed and where the distance to a transfer part is more than the image moving distance from a destaticizing means to the transfer part, and operating the destaticizing means in accordance with the detection signal from the detecting means. CONSTITUTION:A destaticizing device 20 which erases the electrostatic charge on the surface of a photosensitive drum 1 is provided between an electrifier 4 and a developing device 6, and a detector 21 for the passage of the rear end of recording paper is provided in the position on the route for the recording paper to be fed where the distance from the transfer part is more than the image moving distance from the position where the device 20 is provided to the transfer part. If the device 20 is operated by the rear end detection signal from the device 21 in the case of providing the device 20 and the device 21 respectively approximately equidistantly from the transfer part, the formation of the image in the part deviating from the rear end of the recording paper is prevented. If the distance to the device 21 is large, the rear end detection signal is delayed by the time corresponding to the difference in the distance.

Description

[Detailed Description of the Invention] [Industrial Application] The present invention forms an electrostatic latent image on the surface of a rotating image forming body,
It relates to an electrostatic recording device that performs development and then transfers and records onto recording paper.

[Prior art]

Conventionally, in electrostatic recording devices such as electrophotographic copying machines, when an image that extends beyond the recording paper size is formed on the surface of an image forming body, the image in the extending portion is not transferred to the recording paper. Problems arise such as a heavy burden is placed on the cleaning means to remove it, and more developer is consumed. For this reason, there are known copying machines in which recording paper size information is obtained from the recording paper supply cassette, and based on that information, image formation is not performed in areas that extend beyond the recording paper size. . The copying machine is provided with a charge eliminating means for the surface of the image forming body between the charging means and the developing means, and the charge eliminating means is inactivated when the recording paper passes over the surface of the image forming body corresponding to the recording paper based on information provided by the cassette. Before and after this, the static eliminating means is operated to prevent image formation in the portion where the recording paper protrudes. However, this requires a cassette for each recording paper size, and if a shredded cassette is loaded with recording paper of a smaller size than the specified size, a protruding image will be formed. There's a problem.

[Purpose of the invention]

The present invention provides an electrostatic recording device that prevents image formation on the surface of an image forming body at a portion where the recording paper protrudes based on information directly provided by the recording paper without using a cassette. It is.

[Structure of the invention]

The present invention forms an electrostatic latent image on the surface of a rotating image forming body,
In an electrostatic recording device that transfers and records onto a recording paper after development, a means for removing electricity from the surface of the image forming body is provided between the charging means and the developing means, and the recording paper is transferred to the transfer section at a speed equal to the surface speed of the image forming body. A recording paper trailing edge passage detection means is provided at a position where the distance to the transfer section on the path where the paper is fed at a constant speed is equal to or greater than the image movement distance from the static eliminator to the transfer section, and The electrostatic recording apparatus is characterized in that the static eliminator is operated to prevent an image from being formed on the surface of the image forming body beyond the trailing edge of the recording paper.

Hereinafter, the present invention will be explained in detail based on illustrated examples.

1 to 3FA are schematic side views showing examples of the electrostatic recording device of the present invention, in which 1 is a photosensitive drum rotating in the direction of the arrow; 2 is an IJ-2/G pre-removal electrode;
3 is a cleaning device, 4 is a charger, 5 is an image projection light, 6
1 is a developing device, 7 is a transfer pole, 8 is a transfer pressure roller to which a transfer voltage is applied, 9 is an intermediate transfer roller, 10 is a recording pressure roller, 11 is a separation pole, 12 is a recording paper supply cassette, 13
1 is a paper feed roller, J4 is a registration roller, 15 to 17 are recording paper guides, 18 is a conveyor, and 19 is a fixing device.

Such components are conventionally known.

In the electrostatic recording apparatus shown in FIGS. 1 and 2, the surface of the photosensitive drum 1 is first destaticized by the electrode 2 before cleaning, and then the electrostatic charge shown in FIG. 3 is removed. In the recording device, it is directly cleaned by a cleaning device I'Z3, uniformly charged by a charger 4, and an image projection light 5 is projected onto the charged surface to remove the electrostatic latent. An image is formed, and the electrostatic latent image is developed into a 1-square image by the developing device 6, and in the electrostatic recording device shown in FIGS. The toner image is transferred to the recording paper in a transfer section equipped with two rolling press rollers 8. In the electrostatic recording device shown in Fig. 3, an intermediate transfer roller rotates in the direction of the arrow. The toner image is transferred via the roller 9 onto a recording sheet that is fed by being pressed against the surface of the intermediate transfer roller 9 by a recording suppressing roller 1tO rotating in the direction of the arrow. However, the recording paper sent out from the cassette 12 by the paper feed roller 13 is temporarily stopped by the registration roller 14, and the tip of the toner image completely formed on the surface of the photoreceptor drum 1 is moved to the transfer area (see FIG. 3). In the recording device, the registration roller 14 feeds the recording paper to the transfer unit again so that the leading edge of the recording paper reaches the transfer unit when it reaches the part where the recording pressure roller 10 contacts the intermediate transfer roller 9. It will be done.

In the electrostatic recording apparatus shown in FIGS. 1 and 2, the recording paper onto which the dove image has been transferred is sent by the conveyor 18 to the fixing device 19, where the toner image is thermally fixed, and then released outside the machine. be discharged. In the electrostatic recording device shown in FIG. 3, both the intermediate transfer roller 9 and the recording pressure roller 10 are connected to
The toner image transferred to the recording paper is fixed as is. The operation of the electrostatic recording device as described above is also conventionally known.

Therefore, the electrostatic recording device of the present invention is provided with a static eliminator 20 for erasing the charge on the surface of the photoreceptor drum 1 between the charger 4 and the charger 6, and the charge remover 20 is provided between the charger 4 and the charger 6, and the charge remover 20 is provided to erase the charge on the surface of the photoreceptor drum 1. A trailing edge passage detection device 21 of the recording paper is provided at a position where the distance from the transfer unit on the path of the recording paper is equal to or greater than the image movement distance from the position where the static eliminator 20 is provided to the transfer unit,
When the trailing edge passage detecting device 21 detects that the trailing edge has passed, it operates the static eliminator [20] based on the detection signal to eliminate the charge on the surface of the photosensitive drum 1 corresponding to the portion of the recording paper that is outside the trailing edge. It is designed to be erased. That is, when the static eliminator 20 and the trailing edge passage detection device 21 are each provided at approximately the same distance from the transfer section, if the static neutralization device 20 is activated by the trailing edge detection signal of the trailing edge passage detection device 21, the trailing edge of the recording paper can be removed. Imaging of off-edge portions is prevented. If the distance from the transfer section to the trailing edge passage detection device 21'1 is larger than the distance from the static eliminator 20 to the transfer section, the trailing edge detection signal of the trailing edge passage detection device 21 is determined by the distance difference. By activating the static eliminator 20 with a signal that extends one loaf for a time corresponding to , image formation on the portion outside the trailing edge of the recording paper is similarly prevented. Static eliminator@20 includes halogen lamps, tungsten lamps, fluorescent lamps, electroluminescence, light emitting diode arrays, plasma emitters, xenon discharge tubes, other light sources, or these light sources and reflective members, shutters, optical systems, etc. For the rear end passage detection device 21, a combination of a microswitch, an actuator, a delay circuit, an optical sensor, an ultrasonic sensor, etc. can be used.

In the illustrated example, the trailing edge passage detection device 21 is made up of a combination of a microswitch and an actuator, and also serves as a leading edge passage detection means. When the detection device 21 detects the leading edge of the recording paper, the signal causes the paper feed roller 13 to be activated. Therefore, the recording paper is temporarily stopped when its leading edge reaches the registration roller 14 and is stopped.

After that, as mentioned above, the registration roller 14 rotates at the appropriate timing, so that when the leading edge of the image formed on the photosensitive drum 1 reaches the transfer area, the leading edge of the recording paper has already reached the transfer area. Next, the recording paper is sent to the transfer section, and when the detection device 21 detects that the trailing edge has passed, the static eliminator 20 is activated.

Note that the present invention is applicable not only to electrophotographic copying machines but also to those using electrostatic recording, and the developing device is not limited to a dry type, but may be a wet type. In addition, in the case of an electrophotographic copying machine, the photoreceptor is not limited to a drum-shaped one, but can also be a belt-shaped one, and image projection is not limited to slit exposure, but may also be based on flash exposure. . Of course, the static eliminator may be provided not only after the image projection but also before the image projection.

〔Effect of the invention〕

In the electrostatic recording device of the present invention, since toner does not adhere outside the area to be transferred, ■ there is no wasteful consumption of toner; ■ transfer pole 1 separation pole, transfer pressure roller, intermediate transfer roller, recording pressure Does not stain rollers etc. Therefore,
Cleaning means for the transfer pressure roller, intermediate transfer roller, etc. can be omitted or even if provided, it can be simplified; (2) The load on the cleaning device for the surface of the image forming body is reduced and the device is simplified; Excellent effects can be obtained, such as: (1) recording paper of any length can be used, and even if a cassette is used, a common cassette can be used.

[Brief explanation of the drawing]

1 to 3 are schematic side views showing examples of the electrostatic recording device of the present invention, respectively. 1... Photosensitive drum, 2... Pre-cleaning electrode removal, 3... Cleaning device, 4. Charger, 5. Image projection light, 6... Developing device, 7... Transfer pole,
8 Transfer pressure roller, 9 - Intermediate transfer roller, 10... Recording pressure roller, 11... - Separation pole,
12...Cassette, 13...Paper feed roller, 1
4... Registration roller, 15-17... Recording paper guide, 18... Conveyor, 19 Fixing device, 20
・・Static elimination device, 21・Recording paper trailing edge passage detection device. Patent applicant: Konishiroku Photo Industry Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] (1) In an electrostatic recording device that forms an electrostatic latent image on the surface of a rotating image forming body, then develops it, and then transfers it to recording paper for recording, including a charging means and a developing means. In addition, a means for eliminating static electricity on the surface of the image forming body is provided in between, and a distance from the static eliminating means to the transfer area on the path through which the recording paper is fed to the transfer area at a speed equal to the surface speed of the image forming body is provided. A recording paper trailing edge passage detecting means is provided at a position that is greater than or equal to the image movement distance of , and the static eliminating means is actuated based on a detection signal from the detecting means to form an image on the surface of the image forming body that misses the recording paper trailing edge. An electrostatic recording device characterized in that: (2) The electrostatic recording device according to claim 1, wherein the developing means is a dry developing means, and the transfer to the recording paper is performed via an intermediate transfer member. (5) The electrostatic recording apparatus according to claim 1 or 2, wherein the recording paper trailing edge passage detection means also serves as a leading edge detection means. (4) The image moving distance from the static eliminator to the transfer section and the recording paper conveyance distance from the trailing edge passage detecting means to the transfer section are approximately equal, and the static eliminating means is activated immediately upon receiving a detection signal from the trailing edge passing detecting means. An electrostatic recording device according to any one of claims 1 to 5, in which: