JPH0117588B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying printer device that has both a copying function and a printer function. It is designed to be shared.

There are various types of copy printer devices that use electrophotography, but compared to conventional technology that uses laser light and optical fiber tubes, printers that use image signals mainly aim to reduce the cost and size of the device. It has been proposed to use optical scanning devices that replace optical images, such as liquid crystal optical shutter arrays, plasma display panels, and LED arrays.

However, in the case of these optical scanning devices, a lens is required to form the optical image on the photoreceptor, so two lenses are required in addition to the imaging lens required for the original exposure device for copying. The disadvantage is that it requires a lens.

By the way, in a printer device, since the area ratio of the margin area is larger than the recording area, the recording area is irradiated onto the surface of the charged photoreceptor, and a so-called negative latent image with electric charges is created in the area corresponding to the margin area. It is desired to form a film and perform reversal development. However, in the case of a device that has both a copying function and a printer function, two developing devices, one containing toner for the copy mode and the other developing device containing toner for the printer mode, are required.
This requires multiple transfer corona dischargers, which inevitably increases the size and cost of the device.

Therefore, the present inventors used a photoconductor that is sensitive to both positive and negative charges as a photoconductor, and by switching the charging polarity of the photoconductor surface between the copy mode and the printer mode, the photoconductor can be copied. An electrophotographic copying printer device was previously proposed which is capable of performing regular development when in mode and reversal development when in printer mode.

The present invention provides the above-mentioned copy printer device, in which a movable reflecting mirror is provided on the incident end side of the lens so that one imaging lens can be shared as an optical system required for the copying exposure device and the optical scanning device. An electrophotographic copy printer device that switches the charged polarity of the photoreceptor surface and moves a reflecting mirror according to the copy mode and printer mode, thereby achieving further cost reduction, miniaturization, and ease of operation. Our goal is to provide the following.

Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

FIG. 1 shows an example of an electrophotographic printer to which the present invention can be applied, in which a photoconductor layer made of amorphous silicon or the like and having photosensitivity to positive and negative polarity charging is laminated on a conductive substrate. A first corona discharger 2, a second corona discharger 3, an exposure device 4 for copying, an optical scanning device 5 for a printer, and a developing device are arranged along the rotation direction indicated by an arrow on the outer periphery of a so-called bipolar photoreceptor drum 1. Device 6, transfer corona discharger 7
A cleaning device 8 is disposed below the photosensitive drum 1, and a paper feeding mechanism 9 for recording paper P, transport mechanisms 10a and 10b, and a fixing device 11 are disposed below the photosensitive drum 1, as is known in the art.

The polarities of the voltages applied to the first corona discharger 2 and the second corona discharger 3 are opposite to each other. For example, in the copy mode, the photoreceptor drum 1 is uniformly polarized to positive polarity, and in the printer mode, the polarity of the applied voltage is opposite to each other. In this case, the operations of the first corona discharger 2 and the second corona discharger 3 are selectively switched so as to charge the battery to a negative polarity. Note that the first and second corona dischargers 2,
3 may be used as a single discharger, and the discharge polarity may be changed.

The exposure device 4 for copying includes a light source 14 disposed below a document table 13 on which a document 12 is placed and moves back and forth.
and a self-occurring lens (trade name of a focusing transmitter) 15 that forms the reflected light image on the photoreceptor drum 1.
It is formed by a.

As shown in FIG. 2, the printer optical scanning device 5 includes a liquid crystal optical shutter 16 and a light source 1 provided behind it.
7, and a self-cleaning lens 15b that irradiates the photoreceptor drum 1 with light from the liquid crystal light shutter.The liquid crystal light shutter 16 has an electrode 22 made of a transparent conductive film and a 1 mm Hit
10 to 12 linearly arranged segment electrodes 23
A spacer 24 is arranged between two transparent substrates 20 and 21 formed on each of the substrates, and a nematic liquid crystal 25 is sealed in the gap formed between the two transparent substrates 20 and 21, and two polarizing plates 2 are placed on both sides.
7 and 28 are arranged, and a light shielding film 29 shown by diagonal lines is applied to the polarizing plate 28 on the segment electrode 23 side, leaving a minute line-shaped light passage gap of 70 to 80 μm. The liquid crystal is oriented by an electric signal, and light from a light source 17 provided on the back side is passed through, and a dot-shaped optical image is irradiated onto the photoreceptor drum 1 via a self-occurring lens 15b.

The above-mentioned copy exposure device 4 and printer optical scanning device 5 can be selectively activated or deactivated depending on the copy mode and printer mode. 13, the light source 17, and the liquid crystal light shutter 16 are electrically switched.

The developing device 6, the transfer corona discharger 7, the cleaning device 8, the paper feeding mechanism 9, the fixing device 11, etc. are well known, but the charging polarity of the photosensitive drum is set to positive in the copy mode and positive in the printer mode. When the polarity is negative, the polarity of the toner stored in the developing device 6 is negative, and the polarity of the transfer corona discharger 7 is positive, which is opposite to that of the toner.

By doing the above, in the case of copy mode, regular development is performed on the positive latent image that has positive charges in the recorded area, and in the case of printer mode, the negative latent image has charges of negative polarity in the margin area. Reversal development is performed on the negative latent image.

As described above, the present invention is applied to an electrophotographic printer that uses a bipolar photoreceptor as a photoreceptor and requires separate imaging lenses for the exposure device 4 for copying and the optical scanning device 5.

In the present invention, for example, as shown in FIG.
4. In addition to the copying exposure device 4 comprising a self-occurring lens 15, a movable reflecting mirror 31 is provided on the incident end side of the self-occurring lens 15. In the copy mode, the reflecting mirror 31 is placed at a position where it does not interfere with the reflected light image of the document being incident on the self-cleaning lens 15, and in the printer mode, it reflects the light from the optical scanning device 5 and passes through the self-cleaning lens 15. It is movably installed so that it can be moved to a position where it is incident on the object. Specifically, as shown in the figure, the reflecting mirror 31 is rotatably attached to the side of the path of the reflected light image of the original 12, and in the printer mode, the reflecting mirror 31 is rotated with one end thereof as the base end, or Alternatively, although not shown, the reflecting mirror 31 may be installed in an inclined manner so that the self-occurring lens 1
5. In either case, it can be rotated by a known mechanical or electromagnetic mechanism.
Or it can be moved.

The rotation or movement of the reflecting mirror 31 is performed at the same time as the operation of the first corona discharger and the second corona discharger 3 is switched when switching between the copy mode and the printer mode. For example, as shown in FIG. It is preferable to perform this in conjunction with switching between the exposure device for copying and the optical scanning device for printer. That is, in the copy mode, the first corona discharger 2, light source 14, and document table 13 are enabled, and in the printer mode, the second corona discharger 3 and light source 17 are enabled. At the same time, the changeover switch 32 is operated so that the reflecting mirror 31, which is in the solid line position in FIG. 6, is rotated to the dotted line position.

Thus, in the copy mode, the surface of the photoreceptor drum 1 is positively charged by operating the first corona discharger 2, and then the surface of the photoreceptor drum 1 is illuminated by the light source 14 and the self-cleaning lens 15. A light image corresponding to the image is irradiated to form an electrostatic latent image, which is regularly developed with toner in the developing device 6.

A recording paper P is fed by a paper feeding mechanism 9 and stacked on the photosensitive drum 1 holding this toner image. Then, a positive potential is applied from the back side of the recording paper P by a transfer corona discharger 7 to transfer the toner image onto the recording paper P.

This recording paper P is peeled off from the photoreceptor drum 1 and is further conveyed to the fixing device 11 by the conveyance mechanism 10b, the toner image is fixed on the recording paper P by passing through the fixing device 11, and is discharged from the apparatus. be done.

On the other hand, the photosensitive drum 1 that has completed the transfer process is
The remaining toner is removed by the cleaning device 8, thereby completing one copying process.

Next, in the printer mode, after switching the changeover switch 32, the following operation is performed. That is, the surface of the photoreceptor drum 1 is negatively charged by the second corona discharger 3, and then the liquid crystal light shutter 1
A dot-shaped optical image produced by the liquid crystal optical shutter 16 whose passage of light from the light source 17 is controlled by an electric signal inputted to the photoreceptor 6 passes through the reflecting mirror 31, enters the self-occurring lens 15, and is irradiated onto the photoreceptor drum 1. be done. In this way, a negative electrostatic latent image is formed in which the recorded portion has approximately zero potential, and is reversely developed by the toner in the developing device 6. The subsequent steps are similar to those in the copy mode, and the toner image is transferred onto the recording paper P and fixed to create a desired record (print).

It goes without saying that even if the charging polarity of the photosensitive drum 1, the polarity of the toner in the developing device 6, and the discharge polarity of the transfer corona discharge device are reversed to those in the above embodiment, the same results will be obtained.

As described above, according to the present invention, one imaging lens can be shared as an optical system used in the copy mode and the printer mode, which helps reduce the cost of the entire device, and also frees up internal space. This makes cleaning, management and repair of the equipment easier, and is also effective in further downsizing the equipment.

In addition, in the present invention, by using a photoreceptor that is photosensitized to bipolar charging and switching the charging polarity of the photoreceptor between copy mode and printer mode, the electrostatic potential in copy mode and printer mode is While maintaining the advantage of reversing the charge polarity of the image and performing normal development in copy mode and reversal development in printer mode using a single developing device, the charge polarity switching operation described above can be performed. Since the reflecting mirror is moved at the same time, no special operation is required and the ease of operation of the apparatus is not impaired.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the gist of the present invention. For example, it goes without saying that a plasma display panel, an LED array, etc. can be used as an optical scanning device for a printer.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of a copy printer to which the present invention is applied, FIG. 2 is a perspective view of the optical scanning device shown in FIG. 1, FIG. 3 is a partial perspective view of a self-cleaning lens, and FIG. 4 is a cross-sectional view of the liquid crystal light shutter, FIG. 5 is a diagram for explaining the structure of the segment electrode of the liquid crystal light shutter, FIG. 6 is a side sectional view showing the main parts of the device of the present invention, and FIG. 7 is a cross-sectional view of the liquid crystal light shutter. FIG. 3 is an explanatory diagram showing a switching state between a copy mode and a printer mode. 1... Photosensitive drum, 2, 3... Corona discharger, 4... Exposure device, 5... Optical scanning device, 15...
...Self-Ots Cleanse, 31...Reflector.

Claims (1)

[Claims] 1. A corona discharger is disposed around the outer periphery of the photoconductive photosensitive drum, and a corona discharger is provided to uniformly and selectively charge the photosensitive drum to either positive or negative polarity, and a reflected light image of a document placed on a document mounting table is provided. An electrophotographic copying printer device comprising: an exposure device for copying including an optical system that irradiates a photoreceptor drum; and an optical scanning device for a printer including an optical system that converts an image signal into light and scans it onto the photoreceptor drum. In the photoreceptor, the photoconductor has a photoconductor layer that is sensitive to both positive and negative charges, and the optical system is arranged between the document table and the photoreceptor drum, and includes an imaging lens and an incident end side of the lens. An electrophotographic copying printer device comprising a reflecting mirror movably disposed in a mirror, the charging polarity of the surface of a photoreceptor being switched according to a copying mode and a printer mode, and the reflecting mirror being moved.