JPS5940665A - Electrophotographic method - Google Patents

Abstract

PURPOSE:To remove residual charge efficiently and to copy images of good quality successively, by forming a photoreceptor of two kinds of photoconductive layer having specific spectral sensitivity areas, and using light with specific wavelength properly for the formation and erasure of latent images. CONSTITUTION:The 1st photoconductive layer 24, the 2nd photoconductive layer 25, and the 1st photoconductive layer 26 are laminated on an electric conductive substrate 23; the 1st photoconductive layers 24 and 26 are made of SiO2 layers which have >= about 10<13>OMEGA resistance in the dark, about 30-3,000Angstrom layer thickness, and <= about 500nm spectral sensitivity, and the 2nd photoconductive layer 25 is made of a hydrogen-incorporated amorphous silicon layer which has about 10<11>OMEGAcm resistance in the dark, about 10<7>OMEGAcm resistance in light irradiation, about 5-20mum layer thickness, and <=750nm spectral sensitivity, forming the photoreceptor 11. Said photoreceptor 11 uses light with about 500-750nm wavelength (i) for image exposure and electrostatic latent image formation, and also uses light with <= about 500nm wavelength (ii) for entire-surface exposure, erasing the electrostatic latent image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrophotographic method used in, for example, an electrophotographic apparatus or an electronic printer.

[Technical background of the invention and the period 1i'! 1 point] Conventionally, photoreceptors used in electrophotography are made by forming an amorphous silicon (A-84) layer on an At tram substrate, but amorphous silicon has a dark resistance of 10
Since the distance was only 0 m, only a low surface potential could be obtained even if a large amount of corona charging was performed.

Therefore, in recent years, as shown in FIG.
On top, a first sio whose dark resistance is 1013 Ωm or more,
, layer 2, an amorphous silicon layer 3 having a resistance in the dark of 1011 Ω and a resistance in light irradiation of 107 Ω, and a second SiO2 layer 4 having a resistance in the dark of 1013 Ω or more, which are laminated in this order. body is proposed. This photoreceptor 5
When applied to an electrophotographic process, positive charges are first placed on the second 8102 layer 4 by positive corona discharge.

At this time, negative charges are induced in the At drum substrate 1 due to this charge, but injection into the amorphous silicon layer 3 is prevented by the first S r 02 layer 2 . Then, the amorphous silicon layer 3 is formed by light image irradiation.
Carriers of positive polarity and negative polarity are generated inside, and the carriers of negative polarity travel toward the surface, and the carriers of positive polarity travel toward the substrate l side.

And each carrier is the first and second 5ho2R22r4
is transmitted through the tunneling effect, which neutralizes and erases the surface potential, forming an electrostatic latent image. Then, this electrostatic latent image is erased when the potential is neutralized by the entire surface exposure after the toner development, transfer, peeling, toner charge removal, and l)-ning processes, similar to the above-mentioned light image irradiation. Ru.

As described above, the high resistance first and second S i 02 layers 2
, 4, +5 due to +7kV corona charging.
A surface potential of 00V or more can be applied. It's Kade, 1
By irradiating a light image as weak as 0' Otux, it is possible to achieve a low residual value of 30V or less, which is in the fifth place, so the electrostatic contrast becomes 470V or more, and development with negative polarity toner is also comparable to when using a photoreceptor such as Se. It can be done without any loss in comparison.

However, during light image irradiation and full-surface exposure, carriers with low kinetic energy within the amorphous silicon layer 3 cannot pass through the first and second S io 2 layers 2°4, and the virtual line in FIG. As shown in the first and second
rv 1021m 2+ ' and the amorphous silicon layer 3. This residual carrier is especially at a low temperature (1
For example, as shown in FIG. 2, the residual potential and surface potential increase after approximately 100 copies are made. Unfortunately, when image exposure is performed using white light, as shown in Figure 3, both the SiO2 layer 2.4 and the amorphous silicon layer 3 have spectral absorption sensitivity.
Even the parts of the 300 to 1000 thin film 5i02 layer that are not exposed to light have a low resistance, resulting in blurring of letters, deterioration of solid black ethos, etc., which is a drawback.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its object is to efficiently remove the charge remaining at the interface between the first and second photoconductive layers, and to make it possible to efficiently remove the charge remaining on the interface between the first and second photoconductive layers, thereby making it possible to efficiently remove the charges that remain on the interface between the first and second photoconductive layers. To provide an electrophotographic method in which stable electrostatic contrast can be obtained without fluctuations in residual potential and surface potential even after repeated charging and exposure, and which does not cause blurring or deterioration of images. be.

[Key to the invention]

The present invention provides a first photoconductive layer having a predetermined spectral sensitivity region on a conductive substrate, and a second photoconductive layer having a spectral sensitivity region including the spectral sensitivity region of the first photoconductive layer. An electrostatic latent image is formed on a photoreceptor formed by laminating a photoconductive layer and a photoconductive layer, and the electrostatic latent image is erased by exposing the entire surface to light. In the electrophotographic method, when forming the latent image, light having a wavelength outside the spectral sensitivity area of the first photoconductive layer in the spectral sensitivity area of the second photoconductive layer is emitted, and when removing the upper latent image, It is characterized in that light having a wavelength within the spectral sensitivity region of the first photoconductive layer is used.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIGS. 4 to 8. FIG. 4 shows an electrophotographic apparatus for carrying out the present invention, in which reference numeral 11 denotes a drum-shaped photoreceptor that rotates in a predetermined direction. Around this photoreceptor 1, in the rotational direction, there is a charger 2, an exposure system y, ?
, a fil image device 14, a transfer device 15, a peeler J6, a toner static eliminator 17, a cleaner 18, and a static neutralization lamp 19 are arranged. Further, between the photoreceptor J1, the transfer device 15, and the peeling device 16, there is a transfer path 2θ for paper P, the base end of which is connected to the paper feed device 2, and the end of the path 2θ is connected to the paper feed device 2. They are each connected to a paper discharge section (not shown) via a fixing device 22.

As shown in FIG. 5, the photoreceptor 1 includes a first SiO2 layer 24 as a first photoconductive layer and a second photoconductive layer on an AA drum substrate 23 as a conductive substrate. An amorphous silicon layer 25 as a photoconductive layer and a second SiO2 layer 26 as a first photoconductive layer are laminated in this order.

The first and second SiO□ layers 24 and 26 have a dark resistance of 10 Ωm or more and a layer thickness of 30 to 3000X,
Spectral sensitivity is at wavelengths below 500 nm. The amorphous silicon layer 25 contains hydrogen, has a resistance in the dark of 1011 Ωα, a resistance in the light irradiation of 107 Ωm, and a layer thickness of 5
~20 μm, with spectral sensitivity at wavelengths below 750 nm.

The charger 12 is configured to charge the surface of the photoreceptor 11 by '+j'r' by corona discharge.

The exposure system No. 3 is the sixth exposure system for the exposed surface of the photoreceptor 11.
As shown in the figure, an electrostatic Mj image is formed by performing imaging with light having a wavelength of 500 to 750 nm.

The developing device 14 applies toner a to the electrostatic latent image to form a toner image, and the transferring device 15 transfers the toner image to the light body 1.
Copy from top 1 to transfer path 20.

-Paper■) O above peeler 1
6 peels off the copy paper P from the surface of the photoreceptor 11, and the fixing device 22 fixes the toner image onto the copy paper P.

The toner static eliminator 17 is configured to neutralize the toner a remaining on the surface of the photoreceptor 11 without being transferred onto the copy paper I), and the cleaner 18 removes this toner a.

The static eliminating lamp 19 is designed to erase the electrostatic latent image by exposing the entire surface to light with a wavelength of 5 U Onm or more as shown in FIG. There is.

As a result, a positive charge is placed on the second 8102 layer 26 as shown in FIG. 7 due to the positive corona discharge by the charger J2. At this time, a negative charge is induced in the At drum substrate 23 due to this charge, but the first S
The iO2 layer 24 prevents implantation into the amorphous silicon layer 25. Next, the exposure system 13 uses a lamp with an emission spectral wavelength of 500 to 750 nm or 500 to 750 nm.
Light image irradiation is performed using a strong filter that transmits only light with a wavelength of 5 Q nm. At this time, the first and second SIO layers 24 and 26 act as insulators since they have no spectral absorption in this wavelength range.

Therefore, since the resistance values of the first and second SiO2 layers 24 and 26 do not differ between bright and dark areas, there are no letters on the edges or black solid edges. Since the amorphous silicon layer 25 has a spectral absorption sensitivity in the range of 500 to 75 Q nm, positive and negative carriers are generated as shown in FIG. 7, and the negative carriers reach the surface.
The gear rears of positive polarity each travel toward the board 23 side.

And each carrier has a first and a second 3102171i
" +26 is transmitted through the tunneling effect, and as a result, the surface potential corresponding to the bright part of the original is neutralized and erased, forming an electrostatic latent image. Next, this electrostatic latent image is formed.
Image 9 is developed by toner a, transferred, peeled off, static-eliminated from toner a, and emitted by static-eliminating Landzino 9 after undergoing cleaning bamboo gloss. Lamp 1, whose spectral wavelength is 500 nm or less, only transmits light with a wavelength of 500 Ωm or less. The entire surface is exposed using a filter. At this time, the first and second
Since the SiO2 layers 24, 26 and the amorphous silicon layer 25 have spectral absorption sensitivity, these three layers 24,
Carriers with high energy are generated at 25 and 26, respectively, and the three layers 24 and 25 degrees 26 become conductors. Therefore, the charge on the photoreceptor 1) can be removed without accumulation of charge at the interface with the first and second s+o, MB2, 26 amorphous oxide layer 25,
As a result, stable electrostatic contrast can be obtained without fluctuations in residual potential and surface potential even when charging and exposure are repeated during the copying of a large number of sheets.

Next, an experimental example will be explained. First, a SiO2 layer with a thickness of 300X was formed on an At drum substrate by applying 808CCM of SiH4 gas at a flow rate ratio of 02/SiH4 to 4T.
Next, an amorphous silicon film of 12 .mu.m thick was formed using pure biH4 gas, and a 30.degree. thick SiO2 layer was formed at a 02/SiH4 landscape ratio of 4%, thus forming a photoreceptor. As shown in Figure 2, the spectral absorption sensitivity of the single layer of SiO2 layer and amorphous silicon layer of this photoreceptor is S
The iO2 layer is 479 nm or less, and the amorphous silicon M cuff is 52 nm or less. Then, when forming a latent image, light with a wavelength of 500 to 750 nm is applied to this photoreceptor, and when erasing the latent image, light with a wavelength of 500 nm or less is used, respectively.
As a result of continuous copying of 100 sheets, it was possible to obtain stable electrostatic contrast without any blurring of characters or blurring of black edges, and as shown in FIG. 8, with no increase in surface potential or residual potential.

Although the S r 02 layer is used in the above embodiment, the present invention is not limited to this, and it goes without saying that, for example, a SiN layer or a SiC layer may be used.

〔Effect of the invention〕

As explained above, according to the present invention, on a conductive substrate,
A first photoconductive layer having a predetermined spectral sensitivity region and a second photoconductive layer having a spectral sensitivity region including the spectral sensitivity region of the first photoconductive layer are laminated. In an electrophotographic method in which an electrostatic latent image is formed on a photoreceptor by charging and imagewise exposure, and the electrostatic latent image is erased by exposing the entire surface to light, when forming the latent image, the second
When erasing the latent image, light with a wavelength outside the spectral sensitivity region of the first photoconductive layer in the spectral sensitivity region of the photoconductive layer is emitted. Since the two photoconductive layers are used, the charge remaining at the interface between the first and second photoconductive layers can be efficiently removed.
As a result, stable electrostatic contrast can be obtained without fluctuations in residual potential and surface potential even when many copies are charged at the same time or when exposure is repeated, and excellent features such as no blurring or blurring of images are obtained. Effective 0

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the operation of the conventional example, Fig. 2 is a diagram of the relationship between the number of copies, residual potential, and surface potential in the same conventional example, and Fig. 3 is a diagram of the relationship between the wavelength and spectral sensitivity of the amorphous silicon layer and the SiO2 layer. 4 is a diagram schematically showing an embodiment of an electrophotographic apparatus for carrying out the electrophotographic method according to the present invention, and FIG. 5 is a sectional view showing a photoreceptor of the same embodiment. Fig. 6 is a diagram showing the relationship between wavelength and spectral wavelength during image exposure and full-surface exposure in the same embodiment, Fig. 7 is an explanatory diagram of the operation of the same embodiment,
FIG. 8 is a diagram showing the relationship between the number of copies, residual potential, and surface potential in the same example. DESCRIPTION OF SYMBOLS 11... Photoreceptor, 12... Charger, 13... Exposure system, 19... Static elimination lamp, 23... Conductive substrate (A
t drum substrate), 24... first photoconductive layer (first SiO2 layer), 25... second photoconductive layer (amorphous silicon layer), 26... first photoconductive layer Light guiding layer 1b (second
s to2) sound). Applicant's agent Takehiko Suzue, chef (Fig. 5, Fig. 6 = JL version nm) Fig. 7, Fig. 8 Number of sentences (pages) 1. Indication of the case, Patent Application No. 150934/1982, 2. Name of the invention Electrophotography method 3, Person making the amendment Relationship to the case Patent applicant (3 (17) Tokyo Shibaura Electric Co., Ltd. 4, Agent 6, Specification to be amended (1) Claims in the attached document) (21 Specification, page 7, lines 13 to 14, “1st
"Second Sin2 layer as a photoconductive layer" is corrected to "second Sin2 layer same as first photoconductive layer". 2. Claims (1) A first photoconductive layer having a predetermined spectral sensitivity region on a conductive substrate, and a spectral sensitivity region including the spectral sensitivity region of the first photoconductive layer. An electrostatic latent image is formed on the photoreceptor formed by laminating a second photoconductive layer with a second photoconductive layer, and the electrostatic latent image is erased by exposing the entire surface to light. In the electrophotographic method, when forming the latent image, light having a wavelength outside the spectral sensitivity region of the first photoconductive layer in the spectral sensitivity region of the second photoconductive layer is emitted, and when erasing the latent image, the light having a wavelength outside the spectral sensitivity region of the first photoconductive layer is emitted. An electrophotographic method characterized in that each uses light having a wavelength in the spectral sensitivity region of the first photoconductive layer. (2) The first photoconductive layer is a layer of 810□, SiN, or SiC with a thickness of 30 to 3000×. 2. The electrophotographic method according to claim 1, wherein the second phototetraelectric J- is a hydrogen-containing amorphous silicon layer having a thickness of 5 to 20 μm. (31 The spectral sensitivity of the first photoconductive layer is at wavelengths below 5000 m, and the spectral sensitivity of the second photoconductive layer is 75 Q
Claim 1 or 2 which is at a wavelength of nm or more
The electrophotographic method described in Section. (4) The electrophotography according to any one of claims 1 to 3, wherein the wavelength of the light when forming the latent image is 500 to 750 nm, and the wavelength of the light when erasing the latent image is 500 nm or less. Method.

Claims (4)

[Claims] (1) A first photoconductive layer having a predetermined spectral sensitivity region on a conductive substrate, and a second photoconductive layer having a spectral sensitivity region including the spectral sensitivity region of the first photoconductive layer. A multi-electrostatic latent image is formed on a photoreceptor formed by laminating a conductive layer by charging and imagewise exposure, and the electrostatic latent image is erased by exposing the entire surface to light. In the electrophotographic method, when forming the latent image, light having a wavelength outside the spectral sensitivity region of the first photoconductive layer in the spectral sensitivity region of the second photoconductive layer is emitted; An electrophotographic method characterized in that each uses light having a wavelength in the spectral sensitivity region of the photoconductive layer. (2) The first photoconductive layer is a layer of SiO, stN, or stc with a thickness of 30 to 3000×, and the second photoconductive layer is a hydrogen-containing amorphous silicon layer with a thickness of 5 to 2 μm. An electrophotographic method according to claim 1. (3) The spectral sensitivity of the first photoconductive layer is at wavelengths below 50 Uni, and the spectral sensitivity of the second photoconductive layer is 750 Uni.
Claims (1, iJ, 1st term, 11, 11, 11, force θ, in 2nd term) which are at a wavelength of 1 nm. (4) The wavelength of light when forming a latent image is 5()~750 nm.
The electrophotographic method according to any one of Items 1 to 3, wherein the wavelength of the light at the time of erasing the latent image is 500 ++ m or less.