JPH0473658A - Electrophotographic copier - Google Patents

Abstract

PURPOSE:To form an image having a wide image latitude even by a back light exposure system by using a photoconductive member obtd. by laminating a light receiving film composed of a layer hindering the injection of electric charges, a photoconductive layer and a surface layer contg. a specified atomic% of H atoms on a substrate. CONSTITUTION:A photoconductive member obtd. by laminating a light receiving film 100 on a substrate 101 is used. The film 100 is composed of a layer 102 hindering the injection of electric charges, based on Si atoms and contg. a conductivity controlling substance, a photoconductive layer 103 made of an amorphous material based on Si atoms and contg. atoms of at least one of H and halogen and a surface layer 104 made of an amorphous material contg. 41-70atomic% H atoms as well as Si and C atoms as constituents. An image is formed with high reproducibility even by a back exposure system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic copying apparatus that forms images using an electrophotographic method, such as a digital copying machine or a laser beam printer.

[Prior Art] Conventionally, to form a latent image on a photoconductor, the steps of charging, exposure, development, transfer, separation, and cleaning are usually performed and used repeatedly.

Therefore, for image formation using the exposure method, optical writing using a scanning laser beam is performed using the image exposure method.
A method for erasing the charge in the image area (IAE) and a back shadow exposure method, that is, a method for erasing the charge in the non-image area (BAE)
There is. Further, in the above-mentioned IAE, a reversal development method is adopted in which the developer has the same polarity as the charging polarity, and a high voltage having the opposite polarity to the charging is applied in the transfer process. Furthermore, in the BAE, a regular development method in which the developer has a different polarity is used, and in the transfer process, a high voltage having the same polarity as the charging is applied.

In recent digital copying machines and laser beam printers, an image exposure method using reversal development has been adopted for boat fishing, and the image quality has been improved as described below.

In either case, the beam diameter greatly affects image quality. Generally, the laser beam diameter is set to be thicker than the dot pitch P in order to reduce scanning unevenness. Therefore, the one-dot line width is smaller than the pitch width for positive and larger for negative and positive.

Figure 14 is an explanatory diagram showing the above relationship;
(b) shows positive development, and (b) shows negative development.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, it is necessary to pay attention to the following points.

In other words, recently, by partially improving the base machine through high-mix, low-volume production or modular design, analog copiers and digital/analog copiers with add-on functions built into analog copiers and analog copiers have been able to produce arbitrary images that were not possible with analog copiers. Currently, there is a pressing need to simultaneously design and develop three models, such as digital copiers that can easily perform image processing such as editing functions (for example, can be systemized by combining with OA equipment), and this modular design. Advantages include common parts, common elemental technology, common design, shortened development period, easy production of series products, common use of developer and photoreceptor, and reduction in service costs and production costs. Condition settings such as charging around the photoreceptor, exposure, development, and transfer must be easy to set or change using an IC card or the like. Furthermore, the design
It is easy to position the production-sales route, and although the machines may look the same on the outside, the contents are completely different. In this way, by adopting the above-mentioned method, each part will inevitably be produced with high reliability and high durability, and the mass production effect will also be produced.

Therefore, in adopting the above-mentioned method, we must first keep in mind that we aim to standardize the technology.

In recent years, digital printers using laser scanning based on electrophotography have generally recognized that in image recording technology using laser beam scanning, the size, shape, power, etc. of the laser spot have a large impact on image quality and stability. The image exposure method (IAE) has a wider latitude and is considered to be more advantageous. Furthermore, IAE has become mainstream because it takes advantage of the advantages of short laser lighting time and less laser deterioration. is the current situation, and although the back shadow exposure method (BAE) also has several other advantages, there is a problem in that BAE is no longer adopted.

The present invention attempts to solve these problems. That is, an object of the present invention is to provide an electrophotographic apparatus that is capable of forming images with a wide image latitude even when using a back shadow exposure method without requiring complicated electrical image processing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an electrophotographic copying apparatus of a type in which an electrostatic latent image recorded on a photoconductor member is developed with a developer. The body member includes a support body;
On the support, there is provided a charge injection blocking layer containing a substance that controls conductivity using silicon atoms as a base material, and a non-charge injection blocking layer containing silicon atoms as a base material and containing a small amount of hydrogen atoms and halogen atoms (both containing one of them as a constituent element). A photoconductive layer made of a crystalline material and exhibiting photoconductivity, and a surface layer made of an amorphous material containing silicon atoms, carbon atoms, and hydrogen atoms as constituent elements. and the surface layer contains 41 to 70 at.% of hydrogen atoms, and the means for forming a latent image on the photoconductor is a digital copying member that outputs a digital image. The image is formed using an optical writing method in the machine and a background exposure method.

[Function] According to the present invention, the photoconductive member consists of a support and a photoreceptive layer provided on the support, and the photoreceptor layer controls conductivity using silicon atoms as a matrix. a photoconductive layer that exhibits photoconductivity and is composed of an amorphous material containing at least one of hydrogen atoms and halogen atoms using silicon atoms as a host; and silicon atoms and carbon atoms. and a surface layer made of an amorphous material containing hydrogen atoms as constituent elements, the sensitivity of the photosensitive material, that is, the γ value in the EV curve, has linearity on a linear scale, Even in back shadow exposure (BAE), the image pattern can be faithfully reproduced without increasing the erased area of the latent image due to slight light leakage or flare.

[Example] FIG. 1 is an EV characteristic curve of a photoconductor used in the present invention. Curve A in the figure is an amorphous silicon (hereinafter referred to as A-3i) photoconductor used in the present invention, and curve B is an OPC of a normal functionally separated organic photoconductive material that can be compared with the present invention. be. The electrical, optical, and photoconductive properties of the above two types of materials, such as the dark resistance value of photoconductivity, photosensitivity, and photoresponsiveness, are determined individually. Therefore, for boat fishing, when the EV curve of A-3i is plotted on a linear scale, it shows almost linearity from dark potential ■ to light potential ■, and the γ value is approximately γ= It is close to 1.0. However, the hem of the VL section has a slight tail,
It remains as a residual potential. On the other hand, as shown in the same figure, OPC has a very high γ in the high potential part, and responds sensitively (that is, has fast sensitivity) even to minute laser irradiation, and the latent image potential is attenuated,
The image density becomes unstable due to the decrease in Vo.

Here, the material and treatment of the photoconductive material A-3i used in the present invention will be explained. For example, on an aluminum cylinder mirror-finished using the glow discharge method according to the manufacturing conditions shown in Table 1, a charge injection blocking layer containing silicon atoms as a matrix and a substance that controls conductivity, and silicon atoms An amorphous material containing at least one of a hydrogen atom (old and a halogen atom (X)) as a base material,
So-called hydrogenated amorphous silicon, halogenated amorphous silicon, or halogen-containing hydrogenated amorphous silicon [hereinafter referred to generically as rA
-3i ()(,X) Use J. ] Consisting of
It has a photoreceptive layer consisting of a photoconductive layer exhibiting photoconductivity and a surface layer made of an amorphous material containing silicon atoms, carbon atoms, and hydrogen atoms as constituent elements, and in the surface layer: It contains 41 to 70% hydrogen atoms.

Table A-3i used in the present invention may also have a long wavelength light absorption layer that absorbs long wavelength light between the support and the charge injection blocking layer (or, in addition, Between the support and the long wavelength light absorption layer or between the support and the charge injection blocking layer, at least one of a nitrogen atom, an oxygen atom, a carbon atom, a silicon atom, and optionally a hydrogen atom and a halogen are present. It may have an adhesion layer made of an amorphous material containing a small number of atoms.

The electrophotographic light-receiving member of the present invention will be described in detail below.

FIGS. 2 to 4 are structural diagrams schematically shown to explain some typical layer structures of the electrophotographic light-receiving member used in the present invention, and in the figures, 100 is a light-receiving layer. ,1
01 is a support, 102 is a charge injection blocking layer, 103 is a photoconductive layer, 104 is a surface layer, 105 is a free surface, 10
6 is a long wavelength light absorption layer, and 107 is an adhesive layer.

That is, the electrophotographic light receiving member shown in FIG.
A photoreceptive layer 100 is provided on 01, and the photoreceptive layer 100 has a charge injection blocking layer 102, a photoconductive layer 103, and a surface layer 104 in order from the bottom.

Further, the electrophotographic light-receiving member shown in FIG.
A photoreceptive layer 100 is provided on the photoreceptive layer 1.
00 has, in order from the bottom, a long wavelength light absorption layer 106, a charge injection blocking layer 102, a photoconductive layer 103, and a surface layer 104.

Furthermore, the electrophotographic light-receiving member shown in FIG.
1, a light-receiving layer 100 is provided on the light-receiving layer 1, and the light-receiving layer 100 is, in order from the bottom, an adhesive layer 107, a long-wavelength light absorption layer 1
06, a charge injection blocking layer 102, a photoconductive layer 103, and a surface layer 104.

Here, a comparison was made between a simulated image and an actual printed image using the A-3i and OPC.

First, a latent image simulation and a light energy distribution simulation were performed based on the EV curve shown in FIG.

As calculation contents of the simulation, first, turning on a one-dot black dot laser will be explained.

The input parameters are the spot diameter (ΔX, Δy) in Figure 5.
Pitch ly: Indicated by 1y in FIG. 6; Average light amount φm: Indicated by φm in FIG.

The output parameters are: First, the peak light amount ry of the isolated I Line is determined from the above parameters.

Second, using Iy, the light distribution F in the X direction of the isolated scanning line is
Find (x).

Indicated by The cross section of and G(y) can be calculated.

On the other hand, a one-dot white spot (laser 0FF) will be explained.

Regarding F (x) and G (y) in Fig. 1θ,
Here, ERF(a) is eroor function
, and is indicated by . Nao. Further, the distribution of F (x) is shown in FIG.

Iy is determined by the first method, and F (x) is determined by the second method.
is found, that is, the distribution in the main scanning direction is found, and the sub-scanning distribution is the peak value of the main scanning distribution, F(x)x−o.
Find by multiplying by ssian. That is, y2 G (y) = F (XL-oX e Δy2
In other words, it is F (x) in the scanning spot of FIG. 9. Therefore, using the above equation, the reproducibility of the thin line in the main scanning section and the sub-scanning section was determined.

FIG. 11 shows the calculation results of image simulation for one dot white point (laser 0FF), that is, background exposure, where the solid line is A-3i and the broken line is OPC.

The slice level is for removing potential ripple unevenness and is equivalent to a background fog removal bias. The horizontal axis shows the latent image distribution [μm], and the vertical axis shows the potential distribution [V]. The −-like surface potential distribution obtained by charging is caused to decay by irradiating with a laser beam. It forms a latent image.

In other words, the peak of the mountain corresponds to ■l1l (dark part), and the ripple part at the bottom corresponds to VL (bright part) when the laser is irradiated.
corresponds to

As can be seen from FIG. 11, the cross section of the white spot in BAE is clearly wider in A-3L.

Next, Fig. 12 shows a one-dot black point (laser ON), that is, in IAE, a slice level is set to remove background fog, and the solid line shows the simulation result of the latent image distribution at that level. -SL, which is similar to the latent image width at the time of BAE, but it can be seen that in OPC shown by the broken line, the latent image width is further expanded.

The simulation was performed using the laser spot diameter as a parameter. The results of this simulation are shown below.

Here, the laser resolution is set to 400D P I (63,
5 μm/pel), and a one-dot white dot and black dot simulation was performed.

Table 2 As shown in Table 2 above, the laser spot diameter (1/e
2) is taken as a parameter, and is the width of the main scanning section [unit: μm] and the width of the sub-scanning section [unit: μm] of BAE and IAE in each photoreceptor of A-3L and OPC. B
In AE, A-3i has 400D P I
For the latent image potential distribution of (63,5 μm/pel),
The values are almost equivalent. Also, in IAE, B
This shows a tendency opposite to that of AE, and OPC shows a considerably thicker latent image distribution.

Therefore, in order to print out the actual image, 1.
A character generator is used to form a latent image of dots in a row of 3 dots with a length of 93 dots, and an appropriate number in the vertical direction (parallel to the direction in which the paper travels) and the horizontal direction (in the width direction of the paper). Print out using .

Here, naturally, the set of 3 dots is (63.5 μm x 3
= 190.5 μm), it is evaluated that a print faithful to this latent image can be obtained.

The above phenomena were investigated through experiments. In the experiment, images were output using various spot diameters as parameters, and the images were evaluated. Taking into consideration the problem of line width, the evaluation was conducted by using a character generator to generate kanji patterns of about 7 points, vertical lines, horizontal lines, etc. of 190 μm width. Thin lines of characters within an appropriate line width were defined as an acceptable range.

The experimental equipment used our company's NP = 9330, scanning density 400D PI photosensitive drum A-3i, OPC developer negative toner, positive toner development system - component jumping development light source semiconductor laser (λ = 780nm) below 190μm Table 3 shows the results of measuring the line width of the pattern output from the width character generator using a microdensitometer.

Table 3 As shown in Table 3 above, in BAE, A-3i shows a line width of approximately 200 μm, which is at a practical level, but in OPC, the line width is slightly narrower, making it less practical. The lines are too thin. However, I.A.E.
In , the relationship is reversed, especially in OPC
In the IAE, the width is around 220 μm, and the line is rather thick, and in practical terms, the reproducibility of the latent image is poor as it is a collapsed image.

FIG. 13 is achieved by improving the EV curve of the OPC photoreceptor in FIG. 1.

That is, it shows a high potential up to the exposure amount a, and shows a low potential at the exposure amount b. It shows linear characteristics from the α point to the β point.

By the way, the EV characteristic of the B curve of OPC is determined primarily, and this pattern is input into the memory of the microcomputer in advance, and for the γ correction of B, the light intensity of the laser is adjusted to In order to have a table that can convert the B characteristic to the C characteristic, it is possible to change it at the output stage of the laser.

Further, the irradiation light from the point α to the point β may be irradiated using a light cut filter that cuts the regions a and b. The pattern for image formation is determined by the light wavelength component that acts only on the straight line portion of the C curve.

[Effects of the Invention] As explained above, according to the present invention, the photoconductive member has
The photoreceptive layer is composed of a support and a photoreceptive layer provided on the support, and the photoreceptor layer includes a charge injection blocking layer containing a substance that controls conductivity using silicon atoms as a host, and a charge injection blocking layer containing a substance that controls conductivity using silicon atoms as a host. A photoconductive layer composed of an amorphous material containing at least one of a hydrogen atom and a halogen atom as a matrix and exhibiting photoconductivity, and an amorphous material containing a silicon atom, a carbon atom, and a hydrogen atom as constituent elements. The sensitivity of the photosensitive material, that is, the γ value in the EV curve, has linearity on a linear scale. Conventionally, IAE had a wider image latitude, but this By adopting the BAE method of the invention, it is possible to form an image with a wide image latitude comparable to that of IAE.

In addition, conventionally, in order to widen the latitude of BAE, complicated electrical image processing or complicated electrical circuit design was required, but this is no longer necessary, and the design is cheaper, more stable, and easier to perform. It has become possible to standardize technology among analog, digital analog, and digital models.

Furthermore, in module design, it is possible to standardize parts, standardize each elemental technology, and standardize designs accordingly, making it relatively easy to design and develop multiple models at the same time. This has the advantage of shortening the process, reducing production costs, making it easier to create sales strategies and routes, and reducing total costs.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the EV characteristic curve of the photoconductor used in the present invention, FIG. 2 is a cross-sectional view of one layer structure of the electrophotographic light-receiving member used in the present invention, and FIG. Same (A cross-sectional view of another layer configuration, Figure 4 is a cross-sectional view of yet another layer configuration, Figure 5 is an explanatory diagram of the spot diameters ΔX and Δy used in simulation calculations, Figure 6 is the same ( pitch 1
Fig. 7 is the same (illustrative diagram of the average light amount φm, Fig. 8 is an explanatory diagram of the light distribution F (x) in the X direction, Fig. 9 is the same)
The figures are the same (an explanatory diagram of the cross section of the scanning spot, Fig. 10 is an explanatory diagram of the white dot distribution, Fig. 11 is an explanatory diagram of the case of BAE with a one-dot white dot, and Fig. 12 is an explanatory diagram of the same one-dot black dot). An explanatory diagram in the case of IAE, Figure 13 is the OPC of Figure 1.
FIGS. 14(a) and 14(b) are explanatory diagrams showing what was obtained by improving the EV curve of the photoreceptor. FIGS. 14(a) and 14(b) are explanatory diagrams showing a comparison of exposure and development methods. 100... Photoreceptive layer, 101... Support, 10
2... Charge injection blocking layer, 103... Photoconductive layer, 105... Free surface, 106... Long wavelength light absorption layer, 107... Adhesion layer. 104...Surface layer, Fig. 1 Exposure iL: EcμJ /ci) Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. F (xl Fig. Fig. Fig. Fig. Fig. +00 Latent image distribution [μm] Fig. oO Latent image distribution [μm] Diagram Exposure fL:E [μJ/art) Heat b-

Claims (1)

[Scope of Claims] 1. In an electrophotographic copying apparatus of a type in which an electrostatic latent image recorded on a photoconductor member is developed with a developer, the photoconductor member includes a support, and on the support, A charge injection blocking layer containing silicon atoms as a matrix and a substance that controls conductivity, and an amorphous material containing silicon atoms as a matrix and at least one of hydrogen atoms and halogen atoms as a constituent element. a photoreceptive layer consisting of a photoconductive layer exhibiting electrical conductivity and a surface layer made of an amorphous material containing silicon atoms, carbon atoms, and hydrogen atoms as constituent elements; The electrophotographic light-receiving member contains 41 to 70 at. An electrophotographic copying apparatus characterized in that the image is formed using a background exposure method. 2. The electrophotographic copying apparatus according to claim 1, wherein writing on the photoconductor is performed by scanning a laser beam. 3. The electrophotographic copying apparatus according to claim 1, wherein the photoconductor is made of amorphous silicon. 4. The γ value of the E-V characteristic curve has a curve that is almost a straight line on a linear scale in a contrast range between a dark potential V_D and a light potential V_L, which are minimum required for electrophotographic characteristics. Electrophotocopying equipment. 5. Claim 4 having a straight line with a γ value approximating 1.0.
The described electrophotographic reproduction apparatus.