JPS6223865B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms developed images on an image carrier and transfers the developed images to a transfer material.

Conventionally, mechanical impact printers have been widely used as output devices for electronic computers. 2. Description of the Related Art Recent advances in electronic technology have increased the processing power of arithmetic units and storage devices, and as a result, there has been a demand for printers with capabilities that exceed those of conventional mechanical impact printers. Various non-impact printers have been developed to meet these demands.
Among these, the best method is the one that produces information from a computer as an electrostatic latent image on an image support such as a photosensitive material, and this electrostatic latent image is Developed with toner, transferred this developed image to plain paper using corona transfer, etc.
2. Description of the Related Art Printers based on so-called transfer-type electrostatic recording or electrophotographic recording, which fix and output toner images on plain paper, are beginning to be used.

Incidentally, although image forming apparatuses using such a system can use transfer materials of various sizes, stains tend to occur around the transfer device as the size is changed.

For example, if you use a lot of transfer material with a narrow paper width, developer stains will occur on the outside of the paper width of the transfer device, and if you subsequently try to transfer to a transfer material with a wide paper width, the transfer device corresponding to the area outside the narrow paper width will In some cases, parts of the printer did not work properly, leading to the risk of accidents such as uneven printing and missing characters.

The possibility of such accidents has also reduced the reliability of image forming apparatuses as output devices for electronic computers.

The present invention has been made in view of the above points, and enables good and highly reliable image formation.

Hereinafter, details and specific examples of the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic diagram showing a specific example image forming apparatus based on the present invention.

A laser beam emitted from a laser oscillator 1-1 enters an optical modulation system composed of a lens 1-2, an A/O modulation element 1-3 using a known acousto-optic effect, and a lens 1-4. Here lens 1-
Lens 2 serves to focus and project the laser beam onto a Bragg reflection surface generated within the A/O modulation element, and lenses 1-4 convert the laser beam diffracted and diverging from the Bragg reflection surface into a parallel beam of light. It functions to convert into.

The laser beam emitted from the lens 1-4 becomes a parallel beam and enters the beam expander 1-5, where the beam diameter is expanded while remaining a parallel beam.

Furthermore, the laser beam whose beam diameter has been expanded is a polyhedral rotating mirror 1-- having one or more mirror surfaces.
6. The polyhedral rotating mirror 1-6 is mounted on a shaft supported by a high-precision bearing (for example, an air bearing), and is connected to a motor 1-6 that rotates at a constant speed (for example, a hysteresis synchronous motor, a DC servo motor).
7. The laser beam horizontally swept by the polyhedral rotating mirror 1-6 is directed to the photosensitive drum 1-9 by the imaging lens 1-8 having f-θ characteristics.
The image is formed as a spot on the paper, visualized by the electrophotographic process described below, transferred and fixed onto plain paper, and output as a hard copy.

As an example of the electrophotographic process applied to this embodiment, a photosensitive drum whose basic constituents are a conductive support, a photoconductive layer, and an insulating layer, as described in Japanese Patent Publication No. 42-23910 of the present applicant. The surface of the insulating layer 1-9 is uniformly charged positively or negatively in advance by the first corona charger 1-11, and the charged polarity is applied to the interface between the photoconductive layer and the insulating layer or inside the photoconductive layer. Then, the surface of the insulating layer to be charged is irradiated with the laser beam, and at the same time, an AC corona discharge is applied by the AC corona discharger 1-12, and the charge is generated according to the light and dark pattern of the laser beam. A pattern based on the resulting difference in surface potential is formed on the surface of the insulating layer, and the entire surface of the insulating layer is uniformly exposed with a full-surface exposure lamp 1-13 to form a high-contrast electrostatic latent image on the surface of the insulating layer. Further, the electrostatic latent image is formed in a developing device 1-1 using a developer mainly composed of charged colored particles.
4 for visualization.

Next, of the visualized developed images, a portion approximately outside the paper width of the transfer material is cleaned by a cleaning device which will be described in detail later.

That is, the transfer means contamination prevention mechanism is configured such that the developer outside the width of the paper is removed by the blade 1-17 and the removed developer is collected by a blower (not shown).

Further, the visible image is transferred to the fan-hold paper (hereinafter referred to as paper) 1-20 which is pressed onto the photosensitive drum 1-9 by means described later.The charger 1-
18, and then the transferred image is fixed by a fixing means as described below to obtain an electrophotographic print image.Meanwhile, after the transfer is performed, the surface of the insulating layer is cleaned by a cleaning device 1-19. The remaining charged particles are removed, and the photosensitive drum 1-
9 is used repeatedly.

As still another example, the present applicant's Japanese Patent Publication No. 42
- The electrostatic image forming process of electrophotography as described in Publication No. 19748 is applied. That is, a photosensitive drum whose basic components are a conductive support, a photoconductive layer, and an insulating layer is used, and the surface of the insulating layer is uniformly positively or negatively charged in advance by a first corona discharge, and the photoconductive layer A charge having a polarity opposite to the charged polarity is captured on the surface of the insulating layer or inside the photoconductive layer, and an alternating current corona discharge is applied to the charged surface to annihilate the charge on the surface of the insulating layer, and then, The process of irradiating the laser beam as an information signal, forming an electrostatic latent image on the surface of the insulating layer according to the brightness of the laser beam, and then developing the electrostatic image is the same as that of the first embodiment. The same is true.

Note that 1-10 is a pre-static charger, and 1-10' is a pre-exposure lamp. The pre-discharge charger 1-10 makes the surface potential of the photosensitive drum 1-9 constant and uniform, and the pre-exposure lamp 1-10' makes the characteristics of the photosensitive layer constant and uniform, and these work together for cleaning. It functions to erase various previous history, such as residual potential, remaining on the photosensitive drum 1-9 after passing through the device 1-19, and is useful for always obtaining stable images. The present applicant has proposed an electrostatic latent image stabilization method (Japanese Patent Application No. 111562/1984) as a means of always obtaining stable and good images in the electrophotographic process applied to this embodiment.

Reference numeral 1-16 is an electrostatic electrometer for realizing such a means, which measures the electrostatic potential of each photosensitive drum 1-9 by providing a bright area, that is, an exposed area by scanning with a laser beam, and a dark area. .

1-15 is a carrier removal device and developing device 1-14
The carrier mixed with the developer inside the photosensitive drum 1-
9 and prevents it from adhering to the paper or getting mixed into the cleaning device 1-19 or the like.

Next, paper conveyance will be described. Reference numeral 1-20 is an unprinted sheet of paper normally used for output from a computer, etc., and has feed holes at both ends in the width direction.

Reference numeral 1-21 is a holding rod provided to help convey the paper smoothly. Reference numeral 1-22 is a brush that presses the paper against the guide plate 1-23, prevents the paper from floating up when it enters the tractor 1-24, which will be described later, and smoothes the transport of the paper, and removes dust etc. attached to the paper. It also serves as an action.

Reference numeral 1-24 is a known tractor having an array of pins that engage with the feed holes of the paper, and the pins are rotated by the rotation of a tractor shaft (not shown) to convey the paper at a constant rate. 1-25 is a guide roller for conveying the paper.

Reference numeral 1-26 is a separating claw, and as will be described later, the paper is pressed against the photosensitive drum 1-9 by the operation of the transfer guide plates 1-27 and 1-28, and the paper is further separated by the operation of the transfer charger 1-18. The transfer is completed when the photosensitive drum 1-9 is in close contact with the transfer charger 1-9.
Stopping operation of 18 and transfer guide plate 1-27, 1-2
This is to release paper that is stuck to the photosensitive drum 1-9 despite the distance from the photosensitive drum 1-9.

Transfer guide plates 1-27 and 1-28 operate simultaneously in the same direction to press the paper against the photosensitive drum 1-9.

Reference numeral 1-30 denotes a guide roller that has the function of absorbing tension fluctuations applied to the paper during paper conveyance, and is moved to the position shown by the dotted line in the figure according to the tension of the paper.

A fixing roller 1-31 fixes the toner transferred to the paper, and together with a back-up roller 1-32, constitutes a fixing device.

1-31 has a hollow cylindrical shape and has a heat source such as a heater in the center of the cylinder. The fixing roller 1-32 presses the paper onto which the toner has been transferred between it and the fixing roller 1-31, making it easier for the heat from the fixing roller 1-31 to be transmitted to the toner and the paper, and applying high pressure to the toner to fix it. It is a back-up prowler that does this.

1-33 and 1-34 are discharge rollers for discharging the paper on which fixing has been completed, and 1-35 is a paper on which printing has been completed.

FIG. 2 is a perspective view of the transfer device contamination prevention device and the tractor in the above-mentioned embodiment, viewed from the direction A in FIG. 1.

A blade 1-17 has the function of scraping off unnecessary toner adhering to a portion of the drum corresponding to a portion approximately outside the paper width. The toner scraped off here is sucked through the suction port 2-1 of the suction box 2-2, passes through the hose 2-3, and is collected in a filter (not shown). Also, blade 1
-17 and suction box 2-2 are supported by guide shafts 2-4 and 2-5, and tractor 1
- 24 and is moved left and right together with the tractor 1-24 by means of a connecting rod 2-6 attached to the tractor 1-24.

Note that 2-8 is a guide shaft of the tractor 1-24, and 2-7 is a spline shaft that drives the tractor.

In this way, the mechanism for cleaning before transfer is linked with the transfer material conveyance mechanism according to the size of the transfer material, so that the device has extremely excellent operability.

FIG. 3 shows the degree of dirt on the transfer device in the paper width direction when the transfer device means dirt prevention device shown in this embodiment is not used, and is compared with the paper width direction. The paper used here is perforated fanfold paper commonly used in computers. Experiments have shown that when using fanfold paper with sprocket holes, the transfer device is most likely to become dirty from the inside, about 10 mm from the edge of the paper, as shown in Figure 3, followed by the area outside the paper width. will become uniformly dirty. The area about 10mm from the edge of the paper is most likely to get dirty because there are holes in the paper. Therefore, in the device of the present invention,
It is also effective to set the blade of the transfer device stain prevention device so that it is positioned from, for example, about 10 mm inside to the outermost side of the paper width, and in this way, the transfer device is very unlikely to get dirty. Additionally, the blade is linked to the tractor, so that no matter what paper width you use, the relative position of the paper and blade is always maintained.

By the way, in the apparatus of the above-mentioned embodiment, the transfer device (means) contamination prevention device used suction together with the blade.

In particular, this suction is effective for removing developer that accumulates on the blade contact area.

Therefore, it goes without saying that it is better to effectively arrange the suction port around the blade contact portion.

The above-mentioned examples do not limit the present invention,
Of course, various modifications can be made according to the spirit of the present invention.

As described above in detail with the specific examples, the apparatus of the present invention is capable of good image reproduction using transfer materials of various sizes.

Since a good transferred image can always be obtained, a highly reliable apparatus can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating a specific example image forming apparatus based on the present invention. FIG. 2 is a perspective view of a portion of the transfer means stain prevention device. FIG. 3 is an explanatory diagram showing how dirty the transfer device is in a conventional device. In the figure, 1-1: Laser vibrator, 1-2: Lens, 1-3: A/O modulation element, 1-4: Lens,
1-5: Beam expander, 1-6: Polyhedral rotating mirror.

Claims (1)

[Scope of Claims] 1. A moving image carrier, an electrostatic latent image forming means for forming an electrostatic latent image according to image information on the image carrier, and a developing means for developing the electrostatic latent image. , a transfer means for transferring the developed image to a transfer material, and before transferring the developed image, the developer at the side edge of the developed image is removed, leaving a width of the developed image corresponding to the size of the transfer material. An image forming apparatus comprising: a cleaning means for removing the image carrier from the image carrier. 2. The image forming apparatus according to claim 1, wherein the pre-transfer cleaning means includes an elastic cleaning blade that comes into contact with the image carrier. 3. The image forming apparatus according to claim 1 or 2, wherein the pre-transfer cleaning means includes a suction means. 4. In the image forming apparatus according to claims 1 to 3, the pre-transfer cleaning means is movable and has a cleaning width variable according to the size of the transfer material to which the developed image is to be transferred. An image forming apparatus characterized by: