JP2863357B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus which is used in printers and copiers, and which does not require a cleaning process.

[0002]

2. Description of the Related Art Conventionally, when an image is formed on a printer or a copying machine, an electrophotographic recording method based on the Carlson method is generally used. FIG. 3 is a conceptual diagram of a Carlson type electrophotographic apparatus. In the drawing, first, a photosensitive drum 2 charged by corona discharge of a charger 1 is exposed by an exposure device 3, and an image on a document read by an optical unit is formed as an electrostatic latent image. After the electrostatic latent image is developed by the developing device 4, the electrostatic latent image is transferred onto the sheet 8 by the transfer device 5 and fixed by the fixing device 6.

Since the photosensitive drum 2 is used repeatedly, residual toner after transfer is cleaned by a cleaning device 7. In the exposure device 3, in the case of a printer, light as information is imaged on the photosensitive drum 2 by an optical head such as a laser scanner or an LED array head to perform optical writing. And the reflected light is exposed on the photosensitive drum 2.

[0004]

However, in the above-described conventional electrophotographic apparatus, the cleaning device 7 is provided with a residual toner storage section, and the toner removed from the photosensitive drum 2 in the cleaning process is collected. Work to dispose outside is required. For this reason, the collected toner is discarded at the same time as the replacement of the consumable, but the life of the consumable is set shorter accordingly.

The present invention solves the above-mentioned problems of the conventional electrophotographic apparatus, and there is no need to collect and discard the toner remaining in the non-image area by a cleaning process, and it is necessary to shorten the life of consumables. Not to provide an electrophotographic device.

[0006]

For this purpose, in an electrophotographic apparatus according to the present invention, a photosensitive drum, a charging roller which is rotated in contact with the photosensitive drum and charges the surface of the photosensitive drum, and An exposure device that exposes the exposed photosensitive drum by emitting light having a wavelength outside the visible region to form an image portion of an electrostatic latent image on the surface of the photosensitive drum,
And a developing device for forming a visible image by adhering toner to the image portion and sucking the toner remaining on the non-image portion of the photosensitive drum.

Further, a transfer device for transferring the visible image on the photosensitive drum onto a sheet of paper, and a potential difference for adhering toner from the developing device to the image portion and sucking the toner remaining in the non-image portion to the developing device. And potential difference forming means for forming

[0008] The toner has a characteristic that it has a high transmittance for light having a wavelength other than the visible region and a low transmittance for light having a wavelength in the visible region.

[0009]

According to the present invention, as described above, in an electrophotographic apparatus, a photosensitive drum, a charging roller rotated in contact with the photosensitive drum and charging the surface of the photosensitive drum, and a charged roller are charged. An exposure device that exposes the photosensitive drum by emitting light having a wavelength outside the visible region to form an image portion of an electrostatic latent image on the surface of the photosensitive drum; And a developing device for suctioning toner remaining on the non-image portion of the photosensitive drum.

A transfer device for transferring the visible image on the photosensitive drum onto a sheet of paper, and a potential difference for adhering toner from the developing device to the image area and sucking the toner remaining in the non-image area to the developing device. And potential difference forming means for forming

[0011] The toner has such characteristics that it has a high transmittance for light having a wavelength other than the visible region and a low transmittance for light having a wavelength in the visible region. In this case, when light having a wavelength outside the visible region emitted by the exposure device passes through the toner and reaches the photosensitive drum, exposure is performed.

When the potential difference forming means forms a potential difference between the developing device and the photosensitive drum, the Coulomb force generated by the potential difference causes toner to adhere from the developing device to the image portion, while the non-image The toner remaining in the section is sucked by the developing device.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view of the electrophotographic apparatus of the present invention, and FIG. 2 is a view showing the spectral transmittance of toner used in the electrophotographic apparatus of the present invention. In the figure, 11
Is a photosensitive drum, 12 is a charger, 13 is an optical head as an exposure device, 14 is a developing device, 15 is a transfer device, 16 is paper,
Reference numeral 17 denotes a toner. A charger 12, an optical head 13, a developing device 14, and a transfer device 15 are provided around the photosensitive drum 11. The toner 17 is transferred to the sheet 1 by the transfer unit 15.
The toner 17a is transferred onto the photosensitive drum 11, but remains untransferred on the photosensitive drum 11.

A charging roller is used as the charger 12. Therefore, even if the toner 17a remains on the photosensitive drum 11 after the transfer, if the layer of the toner 17a is thin,
The photosensitive drum 11 can be uniformly charged to such an extent that there is no practical problem. The optical head 13 includes a laser scanner, an LED array head, and the like, modulates light with a data signal, and exposes the photosensitive drum 11.

The toner 17 has a wavelength of 700 nm.
Those having a high transmittance in the infrared region and a low transmittance in the visible region are used. Light having a wavelength of 700 nm or more belongs to a region that cannot be sensed by human eyes, and light having a wavelength in this region passes through the toner 17 while visible light is
7 will be absorbed. Therefore, the toner 17 looks almost black to human eyes. Therefore, the optical head 1
The wavelength of light emitted by the semiconductor laser or LED of No. 3 is 800
If the thickness is in the range of up to 1000 nm, the photosensitive drum 11 can be exposed even when the toner 17 adheres to the surface of the photosensitive drum 11. In order to give the toner 17 the above-described transmittance characteristics, a dye such as nigrosine may be added as a coloring material. On the other hand, a phthalocyanine-based photoconductor may be used to operate the photoconductive drum 11 in an infrared region.

In the developing device 14, for example, the toner 17
Using a one-component non-magnetic toner as the developing roller 14a
And the photosensitive drum 11 are in contact with each other. A voltage is applied to the developing roller 14a, and a potential difference is formed between the developing roller 14a and the surface of the photosensitive drum 11. The toner 17a remaining in the non-image area on the photosensitive drum 11 is sucked by the Coulomb force toward the developing roller 14a due to a potential difference between the developing roller 14a and the photosensitive drum 11 in the developing device 14, and is cleaned. On the other hand, in the image portion, the remaining toner 17
Since the photosensitive drum 11 is exposed through a, the Coulomb force due to the potential difference between the developing roller 14a and the photosensitive drum 11 acts in a direction to attract the remaining toner 17a to the photosensitive drum 11 side. Therefore, although new toner 17 adheres during development, there is no density difference between the portion where the remaining toner 17a exists and the portion where it does not exist. If the remaining toner 17a is not transparent to the light emitted from the optical head 13, the portion where the toner 17a remains is not sufficiently exposed, and the amount of the toner 17 attached is smaller than the portion where the toner 17a does not remain. As a result, blank printing will occur.

Although a transfer roller or a corona discharger can be used as the transfer device 15, a transfer roller is preferable because it has a higher transfer efficiency. The toner 17 transferred to the paper 16 is fixed by a fixing device (not shown). In the above embodiment, the optical head 13 is used as an exposure device. However, in a copying machine, a halogen lamp or the like is used as a light source because exposure is performed by light reflected from a document portion. Since the halogen lamp contains a large amount of infrared rays, it can be applied to the electrophotographic apparatus of the present invention. When a color toner is used, the wavelength of light emitted by the optical head 13 is adjusted to the transmission region because the color toner transmits light outside the infrared region.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0019]

As described above in detail, according to the present invention, in an electrophotographic apparatus, a photosensitive drum and a charging roller which is rotated in contact with the photosensitive drum to charge the surface of the photosensitive drum are provided. , The charged photosensitive drum,
Exposure is performed by emitting light having a wavelength outside the visible region, and an exposure device that forms an image portion of the electrostatic latent image on the surface of the photosensitive drum, and forms a visible image by attaching toner to the image portion, A developing device for sucking toner remaining on the non-image portion of the photosensitive drum; a transfer device for transferring a visible image on the photosensitive drum to paper; and a toner for adhering toner from the developing device to the image portion. And a potential difference forming unit for forming a potential difference for sucking the toner remaining in the unit into the developing device. The toner has a characteristic that the transmittance is high for light having a wavelength other than the visible region and the transmittance is low for light having a wavelength in the visible region. In this case, a potential difference is formed between the developing device and the photosensitive drum to cause toner to adhere to the image portion from the developing device and to attract the toner adhered to the non-image portion to the developing device. It emits light of a wavelength. Then, a toner is used which has a high transmittance for light having a wavelength other than the visible region and a low transmittance for light having a wavelength in the visible region.

Therefore, the toner remaining on the non-image portion of the photosensitive drum after the transfer reaches the developing device, is sucked into the developing device by the Coulomb force due to the potential difference between the photosensitive drum and the developing device, and is collected. In the image area, the photosensitive drum is exposed through the remaining toner, so that the toner of the developing device adheres to the photosensitive drum by Coulomb force. Then, a visible image is formed by the remaining toner and the new toner. Since the toner remaining in the image portion does not hinder the exposure, a sufficient potential difference can be formed between the photosensitive drum and the developing device. Therefore, a sufficient amount of toner can be adhered to the image portion, and the blank print does not occur.

Further, since the toner remaining in the non-image area can be collected by the developing device, the use efficiency of the toner is improved, and the life of the consumables can be prolonged.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrophotographic apparatus according to the present invention.

FIG. 2 is a diagram showing the spectral transmittance of toner used in the electrophotographic apparatus of the present invention.

FIG. 3 is a conceptual diagram of a Carlson-type electrophotographic apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Photosensitive drum 12 Charging device 13 Optical head (exposure apparatus) 14 Developing device 15 Transfer device 16 Paper 17, 17a Toner

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-133180 (JP, A) JP-A-3-116178 (JP, A) JP-A-2-271371 (JP, A) JP-A-63-133 144360 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 15/08 G03G 9/08 G03G 15/02

Claims (1)

(57) [Claims] And 1. A (a) photosensitive drum, a charging roller for charging the (b) said photosensitive drum contact is rotated and the surface of the photosensitive drum, the photosensitive drum was allowed to charge (c), the visible region An exposure device that forms an image portion of an electrostatic latent image on the surface of a photosensitive drum by exposing by emitting light having a wavelength other than the above; and (d) forming a visible image by attaching toner to the image portion. And (e) a transfer unit for transferring a visible image on the photosensitive drum to a sheet, and (f) a transfer unit for transferring a visible image on the photosensitive drum to a sheet. A potential difference forming means for forming a potential difference for adhering the toner and attracting the toner remaining in the non-image portion to the developing device. High transmittance, for light of visible wavelength An electrophotographic apparatus characterized by having low transmittance.