JPH054671B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording apparatus using electrophotographic technology, and more particularly to an image recording apparatus suitable for performing image exposure with light including red to near infrared light such as semiconductor laser light.

Using a photoconductor having photoconductivity, the photoconductive photoconductor is uniformly charged and then exposed to imagewise exposure light to form a charge latent image.The charge latent image is developed with toner and the obtained toner image is printed on recording paper. 2. Description of the Related Art Image recording apparatuses that use electrophotographic technology to record images by transferring them to a surface are known. There are various types of photoconductive photoreceptors used in this image recording device, but the representative one is
As shown in the figure, there is a three-layer structure consisting of a conductive substrate 1, a charge transport layer 2, and a charge generation layer 3. This photoconductive photoreceptor has photoconductivity (sensitivity to light) as the charge generation layer 3 absorbs image exposure light and generates holes and electrons using the energy thereof. Since such a photoconductive photoreceptor having a three-layer structure requires only the surface layer to have sensitivity, it has the advantage that charging characteristics are better than those in which the entire layer is a charge generation layer. On the other hand,
Since the surface layer is a charge generation layer, it has a drawback of poor environmental resistance.

In order to compensate for this drawback, as shown in Figure 2,
A photoconductive photoreceptor having a four-layer structure in which a thin protective layer 4 is provided on the surface of a charge generation layer 3 has been proposed. Protective layer 4
An insulator or the same material as the charge transport layer 2 is used for the protective layer 4, but the protective layer 4 is formed as thin as possible in order to minimize adverse effects such as an increase in residual voltage and a light shielding effect. For example, when the charge transport layer 2 is Se, the charge generation layer 3 is Se-Te, and the protective layer 4 is Se, the thickness of the protective layer 4 is 5 μm, preferably 1 μm, while the charge transport layer 2 is 50 μm thick. It was moderately hot. If the protective layer 4 is thin like this, it will deteriorate at high charging voltages, cause large charging fatigue, and will not have sufficient environmental resistance, and will not be able to provide a long-life photoconductive photoreceptor that is resistant to wear and scratches. There were flaws. Furthermore, if the surface is scratched or contaminated with toner or other contaminants, it is impossible to remove it by polishing and reuse it.

Therefore, the object of the present invention is to have a material that does not deteriorate under high charging voltage, has low charging fatigue, has sufficient environmental resistance, is resistant to wear and scratches, and is resistant to surface scratches and contaminant adhesion. It has excellent usability as it can be polished and reused, and it uses a photoconductive photoreceptor that is easy to form and erase charge latent images, making it possible to obtain stable images with high density over a long period of time. An object of the present invention is to provide an image recording device.

To achieve this objective, the present invention includes means for uniformly charging a photoconductive photoreceptor, image exposure means for imagewise exposing the uniformly charged photoconductive photoreceptor to form a charge latent image; In an image recording apparatus comprising a developing means for developing a latent charge image with toner and a transfer means for transferring the toner image formed on the photoconductive photoreceptor onto a recording paper, the photoconductive photoreceptor is formed of a conductive substrate. a first charge transport layer and a first charge transport layer sequentially formed on the surface;
a charge generation layer sensitive to colored light; and a second charge transport layer that transmits the first colored light and is sensitive to the first colored light, at least one of before and after the transfer means. The photoconductor includes an erasing means for erasing charges remaining on the photoconductive photoreceptor.

FIG. 3 is a longitudinal cross-sectional side view of a photoconductive photoreceptor used in the image recording apparatus of the present invention, and shows a conductive substrate 1, a first charge transport layer 2, a charge generation layer 3, a second charge transport layer 5.
It has a four-layer structure. The charge generation layer 3 absorbs the first color light, and the second charge transport layer 5 transmits the first color light and absorbs the second color light.

Next, a specific example of such a photoconductive photoreceptor will be explained.

Example 1 Al or Nesagalas is used as the conductive substrate 1, and an organic photoconductor such as polyvinylcarbazole, pyrazoline, or oxazole derivative is coated on the surface.
The first charge transport layer 2 is coated to a thickness of 10 to 20 μm.
form. On top of that, copper phthalocyanine is coated or vapor-deposited, and Se containing 10% by weight or more of Te
- Charge generation layer 3 with a thickness of 0.1 to 2 μm by depositing Te
form. Furthermore, a mixture of polyvinylphenyl anthracene and trinitrofluoreno or oxazole melted in a proportion of 10 to 50% by weight is coated thereon to form a second charge transport layer 5 having a thickness of 5 to 10 μm. Since this second charge transport layer 5 transports both holes and electrons, it becomes a photoconductive mechanism which will be described later with reference to FIG.

When polyvinylcarbazole is used instead of polyvinylphenylanthracene, it becomes an electron-donating type, which causes hole movement, resulting in a photoconductive mechanism which will be described later with reference to FIG.

In either case, the charge generation layer 3 is sensitive to red to near-infrared light, and the second charge transport layer 5 is sensitive to blue to near-infrared light.
Sensitive to green light.

Example 2 Al is used as the conductive substrate 1, and an adhesive layer is formed by coating the surface with polycarbonate to a thickness of 0.1 to 1 μm (this adhesive layer is not necessary).
The first charge transport layer 2 is formed by depositing Se to a thickness of 30 to 100 μm. The thickness of this first charge transport layer 2 is preferably 40 to 60 μm. Also 5% by weight
It may contain Te, As, In, etc. to a certain degree. On this first charge transport layer 2, Se containing at least % by weight of Te is deposited to a thickness of 0.05 to 2 μm to form a charge generation layer 3. This charge generation layer 3 contains up to % by weight.
It may also contain Te, As, In, etc. Next, as the second charge transport layer 5, Se similar to the first charge transport layer 2 is deposited to a thickness of 2 to 20 μm, preferably 5 to 10 μm. Since Se mainly involves hole movement, it has characteristics similar to the photoconductive mechanism described later with reference to FIG. However, in Se (for example, in highly purified Se), both holes and electrons move, so in this case, the photoconductive mechanism shown in FIG. 4 occurs. The latter is more convenient for image formation. Se transmits red to infrared light and absorbs blue light.

4 to 8 are explanatory diagrams of the photoconductive mechanism of the photoconductive photoreceptor described above.

FIG. 4 shows a case where the second charge transport layer 5 is of the hole and electron transfer type. The first color light (red to infrared light) 6 passes through the second charge transport layer 5, reaches the charge generation layer 3, is absorbed, and generates pairs of holes and electrons. Electrons move through the second charge transport layer 5 to neutralize the surface charge, and holes move through the first charge transport layer 2 to reach the conductive substrate 1. The photoconductive photoreceptor is thus sensitive to the irradiating radiation.

The second charge transport layer 5 generates pairs of holes and electrons on the surface by absorbing second color light (blue to green light), and the holes reach the conductive substrate 1 (Fig. 8). reference). When residual charges exist due to an insufficient amount of first color light, it is better to irradiate with second color light rather than first color light. This is because residual charges often exist in the second charge transport layer 5.

5 to 7 show the case where the second charge transport layer 5 is of the hole or electron transfer type, and here, the hole transfer type will be explained as an example. As shown in Figure 5, the first
The colored light beam 6 passes through the second charge transport layer 5 and is absorbed by the charge generation layer 3, generating pairs of holes and electrons. The holes move through the first charge generation layer 2 and reach the conductive substrate 1 . The electrons hardly move and are trapped near the boundary between the charge generation layer 3 and the second charge transport layer 5. Therefore, the charge applied to the surface layer of the second charge transport layer 5 does not disappear except due to dark decay, and the surface potential is lowered by the first color light 6.
Although it decreases with irradiation, it is observed as a residual potential of 20 to 30% of the initial potential. Since this residual potential (residual charge) has a negative effect on the next image formation, it is necessary to erase the developed toner image at least before and after it is transferred to the recording paper. In order to erase this residual charge, irradiation with the second color light source 7 is performed as shown in FIG. The second colored light beam 7 therefore reaches the second charge transport layer 5
It is preferable to have a component that is absorbed by and generates pairs of holes and electrons. The electrons generated on the surface layer of the second transport layer 5 neutralize the surface charge, and the holes combine with the electrons trapped in the charge generation layer 3 to erase the residual potential.

When a latent charge image formed on such a photoconductive photoreceptor is regularly developed with toner having a charge opposite to that of the surface, and the resulting toner image is electrostatically transferred to recording paper, a transfer electric field is generated. Therefore, the bias charge applied to the back side of the recording paper has the same polarity as the latent image charge. Even if this bias charge passes through the recording paper and accumulates on the surface of the photoconductive photoreceptor, this charge can be erased by irradiation with the second color light beam 7 as shown in FIG. On the other hand, when electrostatically transferring a toner image obtained by reversing the charge latent image to recording paper using toner charged to the same polarity as the surface charge, the bias charge has the opposite polarity to the latent image charge. , when this bias charge leaks to the surface of the photoconductive photoreceptor, the surface charge becomes
Flip as shown. In this case, a second colored light beam 8 having substantially the same components as the first colored light beam 6 is irradiated,
If a hole is generated in the charge generation layer 3, this hole becomes the second
The charge transport layer 5 is moved to neutralize surface charges.
Electrons generated in the charge generation layer 3 combine with holes injected from the conductive substrate 1, but this rate is faster than the holes injected from the conductive substrate 1 reach the surface layer. If it is difficult to erase the residual charge due to reversal development, the surface of the photoconductive photoreceptor may be recharged to the same polarity as the initial charge after the toner image is transferred, and then the second color light beam 8 may be irradiated. It is preferable to irradiate the second color light beam 7 whose main component is a component absorbed by the second charge transport layer 5 . (See Figure 6) Problems caused by the electrostatic transfer process of toner images do not occur when the charge transport layer is of the hole or electron transfer type as explained in Figure 4, but the residual charge is erased in the process. It is preferable to use a second color light beam whose main component is a component absorbed by the second charge transport layer 5.

FIG. 8 shows a photoconductive mechanism when the photoconductive photoreceptor described in FIG. 4 is used for recording in both the copy recording mode and the semiconductor laser beam recording mode, or in the case of recording alone. The light beam 9 is a semiconductor laser beam having a wavelength of 600 to 900 nm, and is transmitted through the second charge transport layer 5 and absorbed by the charge generation layer 3 to generate holes and electrons to form a latent image. The light beam 10 is a copying light beam with a wavelength of 400 to 600 nm obtained from the original to be copied.
The reflected light when the original is irradiated with light with a wavelength of 400 to 600 nm or the reflected light from the original illuminated with white light is passed through a bandpass filter that transmits wavelengths of 400 to 600 nm. This ray of light 10
Since the light does not include red to infrared light, it does not reach the charge generation layer 3, and therefore it is possible to form an independent latent image with both light rays 9 and 10. Even if the document contains images using red stamps, red ink, etc., these can be recorded. The residual potential after the toner image transfer may be removed as described in FIG. 6 or 7.

The photoconductive photoreceptor is not limited to the four layers described above, but may have a plurality of layers having the same function as the one layer described above. For example, the first charge transport layer 2 may consist of two or more layers having different component ratios.

FIG. 9 is a schematic diagram of an image recording apparatus using such a photoconductive photoreceptor, showing an embodiment of the present invention. The surface of the recording drum 22 formed of a photoconductive photoreceptor is uniformly charged by a charger 21, and then scanned and exposed with a semiconductor laser beam 11 to form a charge latent image. This charge latent image is developed by the developing unit 12 to obtain a toner image, but when the photoconductive photoreceptor shown in FIG. A bias voltage is applied to 12 to improve development characteristics. This bias voltage application is effective in preventing fogging during regular development. Next, the surface of the recording drum 22 is uniformly exposed by the residual charge erasing lamp 14. Although this uniform exposure may be omitted, this uniform exposure is effective in improving transfer efficiency in the next electrostatic transfer step when reversal development is employed. The transfer of the toner image onto the recording paper 15 is performed by a transfer device 1.
6, the recording paper 15 is electrically charged under an electric field. After the toner image has been transferred, an AC or DC corona is applied to the surface of the recording drum 22 by a charger 17, and the remaining charge is uniformly exposed by a lamp 18 for erasing residual charges to erase the remaining charges. This corona and uniform exposure are applied to the recording drum 22.
It may be made to act on both simultaneously. Further, it is not necessary to install all of the residual charge erasing lamps 14 and 18 and the residual charge erasing charger 17, and the second charge transport layer 5 is exposed to sensitive light by the photoconductive mechanism of the photoconductive photoreceptor described above. In many cases, the lamp 18 provided is sufficient to perform its function.
Thereafter, the toner remaining on the recording drum 22 is scraped off by the blade 20 into the collection box 19, where it is cleaned and reused. The second charge transport layer 5 formed on the surface of the recording drum 22 (photoconductive photoreceptor) used in the present invention is thick and strong as described above, so even if such a blade cleaning method is adopted, The life of the recording drum 22 will not be significantly reduced.

As described above, according to the present invention, at least a first charge transport layer, a charge generation layer, and a second charge generation layer are sequentially formed on the surface of a conductive substrate as a photoconductive photoreceptor.
This second charge transport layer can be charged to a high potential, has sufficient environmental resistance, and has a thickness that can withstand abrasion, so it has excellent usability. Since the charge remaining in the charge transport layer is erased by colored light to which this layer is sensitive, it is possible to provide an image recording device that can produce stable images with high density over a long period of time.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional side views of a conventional photoconductive photoreceptor, FIGS. 3 to 9 show embodiments of the present invention, and FIG. 3 is a longitudinal sectional side view of a photoconductive photoreceptor,
4 to 8 are explanatory diagrams of the photoconductive mechanism, and FIG. 9 is a schematic diagram of the structure of the image recording apparatus. 1... Conductive substrate, 2... First charge transport layer,
3... Charge generation layer, 5... Second charge transport layer, 1
DESCRIPTION OF SYMBOLS 1... Semiconductor laser beam for image exposure, 12... Developing device, 15... Recording paper, 16... Transfer device, 18...
... Lamp for erasing residual charge, 21 ... Charger, 22
...recording drum.

Claims (1)

[Scope of Claims] 1. means for uniformly charging a photoconductive photoreceptor; image exposure means for imagewise exposing the uniformly charged photoconductive photoreceptor to form a charge latent image; In an image recording apparatus comprising a developing means for developing with toner and a transfer means for transferring the toner image formed on the photoconductive photoreceptor to recording paper, the photoconductive photoreceptor is sequentially formed on the surface of the conductive substrate. a first charge transport layer, a charge generation layer sensitive to a first color light, and a second charge transport layer transparent to the first color light and sensitive to a second color light. An image recording apparatus further comprising uniform exposure erasing means for erasing charges remaining on the photoconductive photoreceptor at least one of before and after the transfer means. 2. In the image recording apparatus according to claim 1, the uniform exposure erasing means recharges the surface of the photoconductive photoreceptor to the same polarity as the latent image charge after the toner image is transferred to the recording paper. An image recording apparatus comprising a charger and a second color light beam generator that applies exposure light to the surface of a recharged photoconductive photoreceptor. 3. In the image recording apparatus according to claim 1, the photoconductive photoreceptor includes first and second charge transport layers containing 90% by weight or more of Se, and 10% by weight of Te.
An image recording device comprising a charge generation layer as described above, wherein the second charge transport layer has a thickness of 2 to 20 μm. 4. The image recording device according to claim 1, wherein the first color light beam imparts imagewise exposure to the photoconductive photoreceptor at a wavelength of 600 nm or more, and the second color light beam has a main wavelength of 400 nm to 600 nm for development. An image recording device characterized by applying uniform exposure to erase residual charges after the process. 5. In the image recording apparatus according to claim 1, both the first color light beam and the second color light beam imagewise expose the photoconductive photoreceptor to form a charge latent image, which remains after being developed. An image recording device characterized by erasing charges. 6. In the image recording device according to claim 1, after uniformly charging the photoconductive photoreceptor, the first color light ray is a semiconductor laser light having an oscillation wavelength of 600 nm or more, and the second color light ray is has a wavelength of 400
An image recording device characterized in that a charge latent image is formed by imagewise exposure containing 600 nm light, and this latent image is developed with a single color toner. 7. The image recording device according to any one of claims 1 to 6, wherein the second charge transport layer transports charges of both positive and negative polarities. 8. In the image recording apparatus according to claim 1, residual charge erasing means before and after transfer or before and after recharging includes means for uniformly exposing the charge generation layer to colored light and a second charge transport layer. An image recording apparatus characterized by separately having means for uniformly exposing colored light to which it is exposed.