JPH0193772A - Image forming method - Google Patents

Abstract

PURPOSE:To decrease black spots and to eliminate interference fringe-like unequal densities by forming an image under prescribed conditions by using a photosensitive body having a specially constituted carrier generating layer contg. a cyanine compd. CONSTITUTION:The photosensitive body is formed by providing a carrier transfer layer 4 on the carrier generating layer 2 contg. at least a carrier generating material 10 consisting of the cyanine compd. (e.g.: the compd. expressed by the formula) and a binder (A). The content ratio of the component 10 to the component A is confined to <=1/2 and the film thickness of the layer 2 to >=1mum. A carrier transfer material is also incorporated into the layer 2. The image is formed on this photosensitive body by forming an electrostatic latent image having 500-900V absolute value of the max. potential of electric charge by irradiation of a semiconductor laser light thereon, then impressing a DC bias voltage having the absolute value lower by 0-200V than the above-mentioned absolute value thereto and subjecting the electrostatic latent image to reversal development.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an image forming method, and particularly to an electrophotographic copying method.

In the electrophotographic copying method of the prior art Carlson method, after the surface of a photoreceptor is charged, an electrostatic latent image is formed by exposure, the electrostatic latent image is developed with toner, and then the visible image is formed. Transfer and fix onto paper, etc. At the same time, the photoreceptor is subjected to removal of adhered toner, neutralization of static electricity, and surface cleaning, and is used repeatedly over a long period of time.

Therefore, as an electrophotographic photoreceptor, it not only has electrophotographic properties such as good charging characteristics, good sensitivity, and low dark decay, but also has good printing durability, abrasion resistance, moisture resistance, etc. even after repeated use. It is also required to have good physical properties and resistance to ozone generated during corona discharge, ultraviolet rays during exposure, etc. (environmental resistance).

Conventionally, electrophotographic photoreceptors mainly contain inorganic photoconductive substances such as selenium, zinc oxide, and cadmium sulfide. Inorganic photoreceptors having a photosensitive layer are widely used.

On the other hand, the use of various organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors has been actively developed and researched in recent years.

For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with high sensitivity and durability by assigning the charge generation function and charge transport function to different substances in the photosensitive layer. ing. In such so-called function-separated type electrophotographic photoreceptors, substances that exhibit each function can be selected from a wide range of materials, so it is relatively easy to produce electrophotographic photoreceptors with arbitrary characteristics. Is possible. Therefore, it is expected that organic photoreceptors with high sensitivity and durability can be obtained.

FIG. 7 shows a functionally separated electrophotographic photoreceptor using such an organic photoconductive substance.

This electrophotographic photoreceptor has a structure in which a carrier generation layer 6 and a carrier transport layer 4 are sequentially laminated on a conductive substrate 1, and is used for negative charging. That is, the photosensitive layer 8 is composed of the carrier generation layer 6 and the carrier transport layer 4. The carrier generation layer 6 has a carrier generation substance 10 dispersed in a binder resin, and the content ratio of the carrier generation substance and the binder resin is usually 2:
The ratio is about 1 to 1:1. Further, the carrier generation layer 6 is a thin layer, and is usually formed to have a layer thickness (film thickness) of about 0.1 to 0.3 μm. Note that the thickness of the photosensitive layer 80 (film thickness) is usually 15 to 30 μm for reasons such as obtaining a sufficient acceptance potential.
It is said to be about m.

In the electrophotographic photoreceptor having the above-mentioned layer structure, since the mobility of holes is higher than that of electrons when negatively charged, a hole-transporting photoreceptor material with good properties can be used. This is advantageous in terms of photosensitivity, etc.

In contrast, few electron-transporting materials have excellent properties or are carcinogenic, making them unsuitable for use. For this reason, the above-mentioned photoreceptor is used for negative charging. In this case, it is advantageous to use a material with a high hole transport ability in order to achieve high sensitivity.

However, in the photoreceptor described above, carrier injection from the conductive substrate or lower layer side tends to occur when negatively charged, as shown in FIG. 7, and as a result, the surface charge disappears microscopically, or It will decrease. Although the cause of such local carrier injection is not clear, it is thought to be due to defects or non-uniformity on the surface of the conductive substrate, non-uniformity in the charge generation layer, or the like.

The following problems arise due to such local carrier injection.

Recently, reversal development has been widely adopted in printers that involve digital processing, but in the reversal development method, a toner image is formed on the exposed area (the area where the surface charge has disappeared, V), and the unused area is A toner image is not formed in the exposed area (portion where surface charge is retained, ■+()).

However, in the reversal development method, if the surface charge microscopically disappears or decreases in the unexposed area due to carrier injection from the substrate or lower layer as described above, toner is developed in that area, and the so-called capri It becomes an image. This type of fog is different from normal capri, and is a phenomenon that occurs when the surface charge on the photoreceptor microscopically disappears or decreases during reversal development as described above, and is called "black spot". There is. These black spots are caused by toner locally adhering to the white background, so they are much more noticeable than when the black background is white, and they significantly reduce the quality of the image, and are inappropriate image defects. be.

When developing an electrostatic latent image using the photoreceptor described above using the regular development method, the surface charge disappears and toner does not adhere to the reduced area and is not developed, so that the so-called An image defect called "white spot" will occur, leading to a deterioration in image quality, but in this case, it is not noticeable because it is a white spot in a black background.

In order to solve the above problems, for example, the following measures can be considered.

That is, as shown in FIG. 8, a blocking layer 7 is provided between the carrier generation layer 6 and the conductive substrate 1, and the
It is conceivable to prevent carrier injection from. However, in this case, transport of holes and/or electrons is suppressed by the blocking layer 7 even during light irradiation, resulting in a decrease in photosensitivity, an increase in residual potential, and an increase in the absolute value IVL1 of the potential of the exposed area. However, the stability of the IV LI during repeated use is also impaired.

Other measures include reducing the content of carrier transport material (hereinafter sometimes referred to as CTM) in the carrier transport layer 4 of FIGS. 7 and 8;
It is conceivable to change the type of binder resin.

All of these are intended to reduce the hole transport ability of the carrier transport layer 4 to suppress carrier injection into the surface of the photoreceptor, but in this photoreceptor, similar to the photoreceptor shown in FIG. , decrease in photosensitivity, increase in residual potential, l
This results in an increase in v Ll and a decrease in IV L1 stability during repeated use, as well as a decrease in temperature characteristics, and particularly at low temperatures, photoreceptor characteristics such as an increase in IV Ll are greatly deteriorated.

As described above, there has been no known photoreceptor that eliminates image defects such as black spots and has good photoreceptor characteristics, and a technical solution to these mutually contradictory problems has been desired.

Furthermore, in recent years, semiconductor laser light sources have been used in electrophotographic copying methods, which are inexpensive, compact, and capable of direct modulation.

Currently, gallium-aluminum-arsenic (G a -A l2-A5
) type light emitting device has an oscillation wavelength of about 750 nm or more. Many studies have been made in the past in order to obtain electrophotographic photoreceptors that are highly sensitive to such long wavelength light. For example, a method was considered to add a new sensitizer to a photosensitive material such as selenium or cadmium sulfide, which has high sensitivity in the visible light region, to extend the wavelength to a longer wavelength. However, there are problems in practical use due to insufficient environmental resistance and toxicity. Furthermore, the sensitivity of many known organic photoconductive materials is usually limited to the visible light region of 700 nm or less, and there are few materials that have sufficient sensitivity in longer wavelength regions, so they are not expected to be highly reliable. It has been difficult to use this method in laser printers that use semiconductor laser light sources.

Furthermore, when an image is formed by irradiating a semiconductor laser beam using a photoreceptor as shown in FIG. 7, for example, density unevenness in the form of interference fringes called moire occurs in a solid image. Therefore, there has been a need for an image forming method that can eliminate moiré.

The purpose of the present invention is to significantly reduce image defects such as black spots in the reversal development method where black spots are likely to occur, and to provide good sensitivity characteristics, residual potential characteristics, and potential stability during repeated use. ,
The temperature characteristics can be obtained.

20 Structure of the Invention and Its Effects The present invention provides an image forming method using a photoreceptor in which a carrier transport layer is provided on a carrier generation layer containing a carrier generation substance and a binder substance. In the photoreceptor, the carrier generating substance in the carrier generating layer is made of at least a cyanine compound, and the content ratio of the carrier generating substance to the binder substance (carrier generating substance/binder substance) is 1.
/2 or less, the carrier generation layer has a film thickness of 1 μm or more, and the carrier generation layer also contains a carrier transport substance, (b) using a photoconductor containing a semiconductor By irradiating the laser beam, an electrostatic latent image is formed in which the absolute value of the highest potential of the charge is soo V to 900 V, and then the absolute value of the highest potential of the charge forming the electrostatic latent image is 0 to 200 V lower than the absolute value of the highest potential of the charge. The present invention relates to an image forming method characterized in that reversal development of the electrostatic latent image is performed by applying a DC bias voltage having an absolute value.

In the photoreceptor used in the present invention, it is extremely important that the content ratio (weight ratio) of the carrier-generating substance to the binder substance is 1/2 or less, and that the film thickness of the carrier-generating layer is 1 μm or more.

That is, conventionally, the content ratio of the carrier-generating substance to the binder substance was usually large, about 2/1 to 1/1, and the thickness of the carrier-generating layer was usually small, about 0.1 to 0.3 μm. . In contrast, the present invention has remarkable features in that the content ratio of the carrier-generating substance is quite small, 1/2 or less, and the thickness of the carrier-generating layer is quite large, 1 μm or more.

By employing such a unique structure in the photoreceptor, in the present invention, it is possible to prevent the surface charge from disappearing or decreasing due to local injection of carriers from the conductive substrate side. Therefore, when reversal development is performed, no black spots are produced on the image, and a remarkable effect can be achieved in that a high-quality image without image defects can be obtained.

The reason why local carrier injection from the substrate side can be prevented is not clear, but it is thought to be as follows.

That is, in the conventional photoreceptor as shown in FIG.
Carriers (holes) injected from the side of the substrate 1 easily pass through the carrier generation layer 6 and reach the surface of the photoreceptor via the carrier transport N4 having high hole transport properties. In other words, the carrier generation layer 6 does not function as a barrier to local carrier injection.

This is because the carrier generation layer 6 is thin as described above.
This seems to be due to reasons such as the low concentration of the binder substance in the carrier generation layer. Conversely, the carrier generation layer should perform the function of generating carriers during light irradiation and injecting them into the carrier transport layer, so it is natural that it cannot function as a barrier to local carrier injection. be.

In contrast, in the photoreceptor of the present invention, the content ratio of the binder substance in the carrier generation layer is very large, which is clearly different from the structure in which the binder substance is contained at a low concentration as in the prior art. There is. That is, even if local carrier injection is to occur, the carrier generation layer effectively functions as a barrier to carrier injection because of the high concentration of the binder substance.

Moreover, since the carrier generation layer has a large thickness of 1 μm or more, the carriers that are about to be injected cannot easily pass through the carrier generation layer, which sufficiently prevents local carrier injection. It is.

In addition, in the carrier generation layer, when the content ratio of the carrier generation substance to the binder substance is set to 1/2 or less and the film thickness of the carrier generation layer is the same as before, fewer photocarriers are generated during light irradiation, and photosensitivity is reduced. will be in short supply. However, in the present invention, since the carrier generation layer has a thick film thickness of 1 μm or more, the content of the carrier generation substance can be kept high as a whole, and the photosensitivity will not be insufficient.

Furthermore, in the present invention, it is important that the carrier-generating layer also contains a carrier-transporting substance.

In other words, if the carrier generation layer is composed of only a carrier generation substance and a binder substance, as the thickness of the carrier generation layer increases, the transport distance of the carrier in the carrier generation layer increases, and as a result, the carrier transport ability decreases. decreases. Similarly, when the content of the binder substance in the carrier/a-generating layer is increased, the carrier transport ability is decreased.

In contrast, in the present invention, since the carrier-generating layer also contains a carrier-transporting substance, even if the thickness of the carrier-generating layer is increased and the concentration of the binder substance is increased, the carrier-generating layer does not contain a carrier-transporting substance. The transport ability of the generated photocarriers does not deteriorate, but rather improves. Therefore, it is possible to always enjoy good sensitivity characteristics, IV L1 characteristics, residual potential characteristics, sensitivity characteristics and potential stability during repeated use.

Here, the carrier transport substance can be added at the time of forming the carrier generation layer, but instead of being added, it may be diffused from the carrier transport layer to the carrier generation layer.

Furthermore, it is important that by employing the photoreceptor having the above configuration, the aforementioned moiré (density unevenness in the form of interference fringes) can be prevented and images with uniform density can be formed.

That is, although the cause of the occurrence of density unevenness in the form of interference fringes on an image is not clear, it is thought to be caused by a core fire.

As shown in FIG. 9, when the surface of the photoreceptor shown in FIG. 7 is irradiated with semiconductor laser light 16, a part of the incident light 16 is reflected by the surface 4a of the carrier transport layer 4 and becomes reflected light 17. The light enters the photosensitive layer 8, is reflected by the substrate surface 1a, and is emitted as emitted light 18. At this time, if the refractive index of the photosensitive layer is n, the thickness is d, the wavelength of the semiconductor laser beam is λ, and the laser beam 16 is incident perpendicularly to the photosensitive layer 8, then there is a gap between the light 17 and the light 18 ( This results in an optical path difference of 2nd-λ/2). Since the semiconductor laser light is coherent, interference occurs between the lights 17 and 18, and nd becomes λ/
When nd is an integer multiple of 2, the intensity of the reflected light is maximum, that is, the intensity of the light entering the carrier transport layer 4 is minimum (according to the law of conservation of energy), and when nd is an odd multiple of λ/4, the intensity of the reflected light is maximum. is minimal, meaning the light entering the interior is maximal. Incidentally, due to manufacturing reasons, d has an unavoidable local unevenness of about 1 μm. Since the laser beam has good monochromaticity and is coherent, the above-mentioned interference condition changes in response to the unevenness in the location of d, causing unevenness in the absorption amount of the laser beam in the carrier generation layer 6, which causes the solid image to become uneven. It is thought that this appears as interference fringe-like unevenness in density. Note that in a normal copying machine, since the light source is not monochromatic light, the width of the density unevenness in the form of interference fringes varies depending on the wavelength, and is averaged out and cannot be seen.

On the other hand, the photoreceptor used in the present invention can solve the above problem. That is, the carrier generation layer has a thickness of 1 μm.
As described above, most of the semiconductor laser light incident on the photosensitive layer is absorbed while traveling back and forth through the carrier generation layer, and is greatly attenuated before returning to the surface of the photosensitive layer. Therefore, local unevenness in the intensity of reflected light due to interference is significantly reduced.Also, since the carrier generation layer itself is thicker, the amount of absorbed light in the carrier generation layer is less likely to be affected by local unevenness in film thickness.

Become.

In addition, as shown in FIG. 11, the film thickness of the carrier generation layer is d.
If CGM is used and the absorption coefficient of the carrier generation layer for semiconductor laser light is k, then according to Beer's law, Φ=Φ. exp (-2kdca*)...
The relationship (I) holds true.

However, Φ. is the intensity immediately after the light enters, and Φ is the intensity when the light is emitted from the carrier generation layer.

In the photoreceptor used in the present invention, in the above formula (1),
Since dCGH is large, the above-mentioned effects can be achieved.

Furthermore, in the photoreceptor used in the present invention, it is important that the carrier generation layer contains a cyanine compound. This improves the potential stability during repeated use of the photoreceptor, resulting in less memory phenomenon, less residual potential, and stability.

Moreover, since this cyanine compound has high sensitivity in a long wavelength region, it is possible to provide a high-performance photoreceptor that is compatible with an image forming method using reversal development using a semiconductor laser as a light source.

That is, since the cyanine compound has high sensitivity to semiconductor lasers, even if the content ratio of the carrier generation substance to the binder substance is 172 or less, the photosensitivity can be maintained at a high level in combination with the increased film thickness of the carrier generation layer. .

In addition, for the same reason, in equation (1) above, the absorption coefficient k of the carrier generation layer can be increased, and the value of Φ can be increased by increasing the film thickness d CGM of the carrier generation layer to 1 μm or more. can be made smaller,
Therefore, the transmittance of the entire semiconductor laser beam is further reduced,
It is thought that it is possible to further reduce the occurrence of density unevenness in the form of interference fringes.

Furthermore, what should be noted in the present invention is that, in addition to the above, the absolute value of the highest potential of the charge represented by IV-1 is limited to a specific range of 1VH1 = 500V to 900V. , the defects described above do not occur. That is, when 1vH1<5oov, it is difficult to obtain the required electric field strength, but when IVHI>900■, the film thickness of the photosensitive layer becomes large, which is undesirable because the sensitivity decreases.

In addition, in the present invention, 1H1 and 1Vocl (DC bias voltage (7) absolute value) (7) difference TEAL IV, 1-IV
It is also important that rct is specified as 0 to 200v. That is, if 1vH1-1vtlcl<OV, fogging will occur, and lvMl-1vac
l > 200v (I, K, K) 7 adhesion (when using a two-component developer) or adhesion of opposite polarity toner (when using a bipolar component developer).

According to the present invention, lv, l = 500 ~ 9
00V (preferably 550-700V), and 4,1-1v ncl=O~200V (
The voltage should preferably be 50 to 150 V), and performing reversal development under these conditions is an essential condition for maintaining high sensitivity and obtaining a good image with high image quality and no black spots.

Moreover, since it is based on the reversal development method, especially when applied to a printer, the area of the text area (black background area) is smaller than the white background area (that is, the exposed area is smaller).
This method is advantageous in terms of preventing deterioration of the photoreceptor, etc., compared to the regular development method.

As described above, according to the present invention, the carrier generation layer itself can be given a function as a barrier against local carrier injection, and the carrier generation layer maintains good optical carrier generation and transport ability. I can do it. Further, due to the synergistic effect of the unique structure of the photoreceptor and the use of a special carrier-generating substance, moiré (density unevenness in the form of interference fringes) can be prevented while maintaining high sensitivity. Therefore, even in an image forming method using a reversal development method using semiconductor laser light, which tends to cause black spots and moiré, these image defects can be significantly reduced and high-quality images can be stably provided. It is possible to maintain good sensitivity characteristics, residual potential characteristics, sensitivity characteristics and potential stability during repeated use, and there is no deterioration in temperature characteristics. In other words, the mutually contradictory problems of significantly reducing both image defects such as black spots and moiré and maintaining good photoreceptor characteristics have been technically solved.

Generally, in the carrier generation layer, a particulate carrier generation substance and a carrier transport substance are bound together by a binder substance. That is, they are dispersed in the layer in the form of pigments.

The carrier transport substance contained in the carrier generation layer has an ionization potential compatible with that of the cyanine compound (
Matching) is preferred. It is thought that this allows the above-mentioned effects to be better achieved. Further, the carrier transporting substance is preferably one having excellent compatibility with the binder substance.

As a result, turbidity and opacity do not occur even if the amount of the binder substance is increased, so the mixing ratio with the binder substance can be set at a very wide range. The layer is uniform and stable, resulting in better sensitivity and charging characteristics.
Furthermore, it is possible to use a photoreceptor that can form clear images with high sensitivity.

Furthermore, especially when used in repeated transfer type electrophotography, it is possible to achieve the effect that fatigue deterioration does not occur.

The structure of the photoreceptor used in the present invention, such as an electrophotographic photoreceptor, can take various forms.

A general configuration is illustrated in FIGS. 1 and 2.

In the photoreceptor shown in FIG. 1, a carrier generation layer 2 based on the present invention is provided on a conductive substrate 1, and a carrier transport layer 4 is provided on this. A photosensitive layer 5 is configured. The carrier generation layer 2 contains a carrier generation substance 10 and a carrier transport substance (which is compatible with the binder resin).

In the photoreceptor shown in FIG. 2, an intermediate layer or subbing layer 3 is provided between the conductive substrate 1 and the photosensitive layer 5.
Its main function is as an adhesive layer. The thickness of layer 3 is preferably within the range of 0.03 to 20 μm.

In the photoreceptor shown in FIGS. 1 and 2, an intermediate layer having a blocking function or the like may be provided between the carrier generation layer and the carrier transport layer.

Further, a protective layer (protective film) may be formed on the surface of the photoreceptor in order to improve printing durability, for example, a synthetic resin film may be coated.

In the carrier generation layer, the content ratio of the carrier generation substance to the binder substance should be 1/2 or less, preferably 173 to 1/20, and 1/4 to 1/2.
It is more preferable to set it to 10. When the content ratio of the carrier-generating substance is larger than the above range, black spots and the like appear significantly or tend to appear. However, if the proportion of the carrier-generating substance is too small, the photosensitivity and the like will be rather reduced.

The thickness of the carrier generation layer is 1 μm or more, preferably 2 μm or more, and more preferably in the range of 5 to 25 μm. If the film thickness is smaller than the above range, carrier injection may not be blocked or may be difficult to block. However, if the film thickness is too large, the photocarriers have to travel a long distance, and in general, it tends to be difficult to obtain sufficient transport ability, and therefore, the residual potential tends to increase during repeated use. The thickness of the carrier generation layer is preferably 3/4 or less of the thickness of the entire photosensitive layer, and if this thickness ratio is greater than the above range, the charging potential tends to decrease.

The film thickness ratio of the carrier generation layer and the carrier transport layer is (film thickness of carrier generation layer: film thickness of carrier transport layer) = (1:20)
) to (1:1).

The thickness of the carrier transport layer is preferably 2 μm or more. If the film thickness is less than 2 μm, the surface of the carrier transport layer may be mechanically damaged during repeated use due to development, cleaning, etc. Parts may be scratched off, or black lines may appear on the image.

The thickness of the entire photosensitive layer is preferably within the range of 10 to 40 μm, and more preferably within the range of 15 to 30 μm. If the film thickness is smaller than the above range, the charging potential will be lower due to the thinner film, and the stiffness resistance will also tend to decrease. Furthermore, if the film thickness is larger than the above range, the residual potential will increase on the contrary, and the same phenomenon as described above will occur when the carrier generation layer is too thick, making it difficult to obtain sufficient transport performance. Therefore, the residual potential tends to increase during repeated use.

The content of the carrier transport substance in the carrier generation layer is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, based on 100 parts by weight of the binder substance.

If the content of the carrier transport substance is larger than the above range, the film strength tends to decrease, and if the content is smaller than the above range, the carrier mobility in the CGL decreases, resulting in an increase in residual potential and a decrease in photosensitivity. This tends to cause image defects to occur.

The content ratio of the carrier-generating substance and the carrier-transporting substance in terms of carrier mobility is such that the weight ratio (carrier-generating substance:carrier-transporting substance)=(1: 100) ~ (5:
1), preferably (1:10) to (1:1)
It is even more preferable to do so.

When a photosensitive layer is formed by dispersing a granular carrier-generating substance, the carrier-generating substance is powder with an average particle size of 5 μm or less and 0.1 μm or more, preferably 2 μm or more and 0.2 μm or more. is preferred. That is,
If the particle size is too large, dispersion in the layer tends to be poor, and if the particle size is too small, it tends to aggregate, which increases the resistance of the layer and increases crystal defects, resulting in a decrease in sensitivity and repeatability. , the charging ability tends to decrease, and there is a limit to miniaturization.

The above cyanine compounds are known, for example, JP-A-58-
There are compounds described in JP 118650, JP 5B-224354, and JP 59-146063.

In the present invention, it is also possible to use one or more other carrier-generating substances in combination with the above-mentioned cyanine compound. Carrier generating substances that can be used in combination include:
anthraquinone pigments, perylene pigments, polycyclic quinone pigments,
Examples include methine squaric acid pigments.

For example, a polycyclic quinone pigment of the following general formula (1) group can also be used in combination as a carrier generating substance.

General formula [I]: (However, in this general formula, Xo represents a halogen atom, a nitro group, a cyano group, an acyl group, or a carboxyl group, p represents an integer of O to 4, and q represents an integer of O to 6. ) Carrier transport substances that can be used in the present invention include, for example, carbazole derivatives, oxazole derivatives, oxadiazole mH monomers, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives, imidazolidine inducers, and bisimidazolidine. derivatives, styryl compounds, hydrazone compounds, pyrazoline derivatives, oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, Examples include one or more selected from poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like.

In addition, there are various pigments as carrier transport substances that have bipolar transport ability when used alone.

Further, different carrier transport materials may be used in the carrier generation layer and the carrier transport layer.

The following general formula (II) or (I) as a carrier transport substance
A styryl compound of [I] can be used.

General formula [■]: (However, in this general formula, R1 and R2 represent a substituted or unsubstituted alkyl group or aryl group, and substituents include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, Use an aryl group.

Ar', Ar'': Represents a substituted or unsubstituted aryl group, and the substituent used is an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, or an aryl group.

R3 and R4 represent a substituted or unsubstituted aryl group or a hydrogen atom, and the substituents used include an alkyl group, an alkoxy group, a substituted amino group, a hydroxyl group, a halogen atom, and an aryl group. ) General formula [■]: (However, in this general formula, R5: substituted or unsubstituted aryl group, R6: hydrogen atom, halogen atom, substituted or unsubstituted alkyl group,
Represents an alkoxy group, an amino group, a substituted amino group, a hydroxyl group, R7, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. ) In addition, the following general formula (IV), (
It is also possible to use hydrazone compounds of V), (V a ), (vb) or (Vl).

General formula [■]: (However, in this general formula, R11 and R9, each a hydrogen atom or a halogen atom, R10 and R■: each substituted or unsubstituted arylene group, Ar': a substituted or unsubstituted arylene group General formula [■]: (However, in this general formula, R12 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted heterocyclic group, R13, R14 and R'' = hydrogen atom, alkyl group, substituted or unsubstituted aryl group, or substituted or unsubstituted aralkyl group.) General formula (Va): (However, in this general formula, RI&: methyl group, ethyl group, 2-hydroxyethyl group or 2-chloroethyl group, R'': methyl group, ethyl group, benzyl group or phenyl group, R11+, methyl group, ethyl group, benzyl group or phenyl group.

General formula (vb): (In this general formula, R19 is a substituted or unsubstituted naphthyl group; R20 is a substituted or unsubstituted alkyl group,
Aralkyl group or aryl group; QZ+ is a hydrogen atom, alkyl group or alkoxy group; R2! and R23 are the same or different groups consisting of a substituted or unsubstituted alkyl group, aralkyl group or aryl group. ) General formula [■]: (However, in this general formula, R24: substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, Ras: hydrogen atom, substituted or unsubstituted alkyl group, or substituted or unsubstituted heterocyclic group) (Q: represents a hydrogen atom, halogen atom, alkyl group, substituted amino group, alkoxy group, or cyano group; S: represents an integer of 0 or l.) In addition, as a carrier transport substance, the following Pyrazoline compounds of general formula [■] can also be used.

General formula [■]: [However, in this general formula, 1:0 or 1, R26 and R2? = substituted or unsubstituted aryl group,
R2a, substituted or unsubstituted aryl group or heterocyclic group, R29 and R3°: hydrogen atom, alkyl group having 1 to 4 carbon atoms, or substituted or substituted aryl group or aralkyl group (provided that R" and Neither R30 is a hydrogen atom, and when l is 0, RZ9 is not a hydrogen atom.) Furthermore, an amine derivative of the following general formula [■] can also be used as a carrier transport substance.

General formula [■]: (In this general formula, Ar', Ar': represents a substituted or unsubstituted phenyl group, and a halogen atom, an alkyl group, a nitro group, or an alkoxy group is used as a substituent.

Ar6: represents a substituted or unsubstituted phenyl group, naphthyl group, anthryl group, fluorenyl group, or heterocyclic group, and substituents include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an aryloxy group, an aryl group, an amino group, Nitro groups, piperidino groups, morpholino groups, naphthyl groups, anthryl groups and substituted amine groups are used. However, an acyl group, an alkyl group, an aryl group, or an aralkyl group is used as a substituent for the substituted amino group. ) Furthermore, a compound of the following general formula (IX) can also be used as a carrier transport substance.

General formula [■]: R''-N-Ar' -N-R32 (However, in this general formula, Ar' represents a substituted or unsubstituted arylene group, and R31, R3t, R33 and R34: represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) Furthermore, a compound of the following general formula [X) can also be used as a carrier transport substance.

General formula [X]: [However, in this general formula, R35SR2h, R2? and R”
are each a hydrogen atom, a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, aryl group, benzyl group, or aralkyl group, R39 and R'' are each a hydrogen atom, a substituted or unsubstituted carbon atom number of 1 to 40 alkyl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, aryl groups, or aralkyl groups (provided that R39 and R'' jointly form a saturated or unsaturated hydrocarbon ring having 3 to 10 carbon atoms) ) R41, R'tSR'' and R44 each represent a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, An amino group, an alkylamino group, or an arylamino group.] When a binder resin is used to form a carrier generation layer, a carrier transport layer, an undercoat layer, an intermediate layer, etc., any binder resin can be used. However, it is particularly preferable to use a high molecular weight polymer that is hydrophobic, has a high dielectric constant, and has the ability to form an electrically insulating film.
Examples include, but are not limited to, the following:

That is, polyethylene, polypropylene, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin,
Phenolic resin, polyhydroxystyrene resin, polyester resin, alkyd resin, polycarbonate resin,
Contains addition polymerization type resins such as silicone resins, melamine resins, methacrylic resins, acrylic resins, polyvinylidene chloride, polystyrene, phenol formaldehyde resins, polyaddition type resins, polycondensation type resins, and two or more of these repeating units. Insulating resins such as copolymer resins, vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, styrene-butadiene copolymer resins, vinylidene chloride-acrylonitrile copolymer resins , polyvinyl butyral, and furthermore, polymeric organic semiconductors such as N-vinylcarbazole.

The above binders can be used alone or as a mixture of two or more.

In addition to the binder resin described above, for example, polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, casein, N-alkoxymethylated nylon, starch, etc. are used for the undercoat layer that functions as an adhesive layer or the like.

As a binder for the protective layer provided as necessary,
Volume resistance: 10'Ω, preferably 101OΩ (
(to) or more, more preferably a transparent resin having a resistance of 10 13 Ω·Cl 11 or more is used. Further, the binder may be a resin that is cured by light or heat, and examples of the resin that is cured by light or heat include thermosetting acrylic resin, silicone resin, epoxy resin, urethane resin, urea resin, phenol resin, Examples include polyester resins, alkyd resins, melamine resins, photocurable cinnamic acid resins, and copolymerized or condensed resins thereof, as well as all other photocurable or thermosetting resins used in electrophotographic materials.

If necessary, the protective layer may contain less than 50% by weight of a thermoplastic resin for the purpose of improving processability and physical properties (preventing 11 cracks, imparting flexibility, etc.). Such thermoplastic resins include, for example, polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, butyral resin, polycarbonate resin, silicone resin, or copolymer resins thereof, such as vinyl chloride-vinyl acetate- Maleic anhydride copolymer resins, polymeric organic semiconductors such as poly-N-vinylcarbazole, and other thermoplastic resins used in electrophotographic materials can all be used.

The carrier generation layer can be provided by the following method.

(a) A method of applying a solution in which a carrier-generating substance, etc. is dissolved in a suitable solvent, or a solution in which a binder is added and mixed and dissolved.

(b) A method in which a carrier-generating substance, etc. is made into fine particles in a dispersion medium using a ball mill, a homomixer, a sand mill, an ultrasonic disperser, an attritor, etc., and a binder is added, mixed and dispersed, and the resulting dispersion is applied.

Dispersing the particles under the action of ultrasound in these methods allows for homogeneous dispersion.

Further, the carrier transport layer can be formed by applying and drying the above-mentioned carrier transport substance alone or by dissolving and dispersing it together with the above-mentioned binder resin.

In this case, in order to contain the carrier transport substance in the carrier generation layer, the carrier transport substance can be dissolved or dispersed in the solution (a) or the dispersion liquid (b) in advance. There is a method of adding transport substances. In this case, it is preferable that the amount of the carrier transport substance added is within the range of 1 to 100 parts by weight per 100 parts by weight of the binder. Alternatively, there is a method in which a solution containing a carrier transport substance is applied onto the carrier generation layer, and the carrier generation layer is swollen or partially dissolved to diffuse the carrier transport substance into the generation layer. When this method is adopted, it is not necessary to add a carrier transporting substance to the carrier generation layer as described above, but it is also possible to carry out the above three methods at the same time.

As the solvent or dispersion medium used for forming the layer, n
-butylamine, diethylamine, ethylenediamine,
Isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone,
Benzene, toluene, xylene, chloroform, 1.2
- Dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide and the like.

The photosensitive layer, undercoat layer, intermediate layer, protective layer, etc. can be provided by, for example, blade coating, dip coating, spray coating, roll coating, spiral coating, or the like. For example, blade coating is suitable for providing layers of a few μm.

In addition, if a polymeric organic semiconductor having a fused aromatic ring or a heterocyclic ring in the side chain is used in the photosensitive layer together with the carrier transport substance described above, this polymeric organic semiconductor has the property of generating photocarriers by absorbing ultraviolet light. It effectively contributes to photosensitization, and therefore the tail of the discharge curve becomes sharper, which may improve the sensitivity particularly in the low electric field region.

In addition, the polymeric organic semiconductor has high absorbance in the ultraviolet light region and absorbs most of the ultraviolet light, and has a kind of filter effect on ultraviolet light, so it has the effect of preventing deterioration of the carrier transport substance. In some cases, the ultraviolet light stability and durability of the photosensitive layer can be improved.

Examples of the above-mentioned polymeric organic hemi-tetramers include the following, but are not limited to these.

(XI-4) t CH-CH,→-n H2 ■ (XI-13) -te- CHCHz→-n C;0 (X I-14) (X I-15) (XI-16) CH- CHI〒n −-cH-cH2→-nsuO-C
HG Hz〒n CH.

(X I -18) (X I -19) (X I -20) m-CHCHz→-n Among the above-mentioned polymeric organic semiconductors, poly-N-vinylcarbazole or its derivatives are highly effective and are preferably used. It will be done. Such poly-N-vinylcarbazole derivatives are those in which all or part of the carbazole ring in the repeating unit is substituted with various substituents, such as an alkyl group, a nitro group, an amino group, a hydroxy group, or a halogen atom.

Furthermore, silicone oil may be present as a surface modifier. Further, an ammonium compound may be contained as a durability improver.

The protective layer may contain an ultraviolet absorber or the like for the purpose of protecting the photosensitive layer, if necessary.

The conductive substrate 1 on which the photosensitive layer is to be provided is a metal plate, a metal drum, or a conductive thin layer made of a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum, palladium, or gold, which is coated or vapor-deposited. , a material provided on a substrate such as paper or plastic film by means such as lamination or the like is used.

Next, preferred embodiments of the present invention will be described.

FIG. 3 is a schematic configuration diagram showing an example of a recording apparatus for carrying out the method of the present invention, FIG. 4 is a schematic configuration diagram of a laser beam scanner for image exposure, and FIG. 5 is a partial cross-section diagram showing an example of a developing device. FIG. 6 is a flow chart for implementing the method of the present invention.

In the apparatus shown in FIG. 3, 23 is a drum-shaped image carrier which has a photosensitive layer made of the above-mentioned organic photoconductive substance and rotates in the direction of the arrow, and 22 is a main charger that uniformly charges the surface of the image carrier 23. 24 is an image exposure device, and 15 is a developing device. 20 is a pre-transfer exposure lamp provided as necessary to facilitate the transfer of the toner image formed on the image carrier 23 onto the recording medium P; 21 is a transfer device; 19 is a separation corona discharger; 12
is a fixing device that fixes the toner image transferred to the recording medium P. Reference numeral 13 has a static eliminator consisting of one or a combination of a static eliminator lamp and a corona discharger for static elimination, and 14 has a cleaning blade or a fur brush for removing residual toner on the surface of the image carrier 23 after the image has been transferred. It is a cleaning device. In a recording device that uses a drum-shaped image carrier 23 like this recording device, the image exposure 24 is the fourth
Preferably, a laser beam scanner as shown in the figure is used.

The operation of the laser beam scanner shown in FIG. 4 will be described next.

The laser beam generated by the semiconductor laser 41 is rotated and scanned by a polygon mirror 43 rotated by a drive motor 42 , passes through an f-〇 lens 44 , has its optical path bent by a reflecting mirror 45 , and is directed onto the surface of the image carrier 23 . It is projected to form a bright line 46. 47 is an index sensor for detecting the start of beam scanning, and 48 and 49 are cylindrical lenses for correcting the inclination angle. 50a, 50b, 5
0C is a reflecting mirror that forms a beam scanning optical path and a beam detection optical path.

When scanning is started, the beam is detected by the index sensor 47, and modulation of the beam by a signal is started by a modulation section (not shown). The modulated beam is applied to an image carrier 23 that is uniformly charged in advance by a charger 22.
Scan above. A latent image is formed on the drum surface by the main scanning by the laser beam 51 and the sub-scanning by the rotation of the image carrier 23.

Further, in a recording apparatus in which the image carrier can take a flat state such as a belt shape, the image exposure can be a flash exposure. As the developing device 15, one having a structure as shown in FIG. 5 is preferably used. In FIG. 5, the thickness t of the developer De and the magnetic raw developer Qe are regulated by a spike regulating blade 63 during conveyance. The spike control blade 63 is made of an elastic metal plate and presses against the surface of the sleeve 61 to control the thickness of the developer being conveyed. A stirring screw 65 is provided in the developer reservoir 66 to sufficiently stir the developer De, and when the developer De in the developer reservoir 66 is consumed, the toner supply roller 6
8 rotates, toner T is replenished from the toner hopper 67. A DC power supply 69 and a protective resistor 70 are connected in series to apply a developing bias to the sleeve 61. Further, the sleeve 61 and the image carrier 23 are arranged facing each other with a gap d in between, and the developer contacts the image carrier 23 in the development area ε, so that t>d.

In the figure, the developing sleeve 61 and the magnet body 62 are indicated by arrows G, respectively.
Although it is shown that the developing sleeve 61 rotates in the F direction, even if the developing sleeve 61 is fixed, the magnet body 62 is fixed, or the developing sleeve 61 and the magnet body 62 rotate in the same direction. It may be something. When the magnet body 62 is fixed, normally, in order to make the magnetic flux density of the magnetic pole facing the image carrier 23 larger than the magnetic flux density of other magnetic poles, the magnetization is strengthened or a magnetic pole of the same or different polarity is attached thereto. The two magnetic poles may be placed close to each other.

In the above-mentioned apparatus, based on the present invention, the electrostatic latent image is charged so that lV, l becomes 500 to 900 V, and during reverse development (DIVHI IVDCI=O~
The voltage shall be 200V. However, vDC is a DC bias voltage applied to the sleeve 61 as a developer transporting carrier facing the image carrier 23.

The method of the present invention as shown in FIG. 6 can be carried out using the recording apparatus as described above.

Figure 6 shows that an electrostatic image is formed by an electrostatic image forming method in which the image exposure area is an electrostatic image with a lower potential than the background area, and development is performed using toner that is charged to the same polarity as the background area potential. This shows an example of reversal development of the present invention, which is performed by adhering.

The example shown in FIG. 6 when the recording apparatus shown in FIG. 3 is used will be explained.

First, the static electricity is removed by the static eliminator 13, and the cleaning device 14
The surface of the image carrier 23 in the initial state, which has been cleaned and has a potential of O, is uniformly charged by the charger 22, and the charged surface is subjected to image exposure 24 by the laser beam scanner shown in FIG. Image exposure is performed such that the potential of the electrostatic image portion becomes approximately 0 upon projection, and the obtained electrostatic image is developed by a developing device 15 (toner T).

E. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited thereby, and of course includes other embodiments with various modifications.

Manufacture of Photoreceptors> First, photoreceptors AL of Examples and photoreceptors AWK of Comparative Examples were manufactured in the following manner. That is, the manufacturing procedure for each photoreceptor is common.

After pulverizing 20 g of the following specified carrier-generating substance with a porcelain ball at 4 rpm for 18 hours, a specified amount of polycarbonate resin "Panlite L-1250J (manufactured by Kijin Kasei Co., Ltd.) was dissolved in 1000 ml of 1,2-dichloroethane. The solution was added and dispersed for another 24 hours until the predetermined P/
A coating liquid for a CGL (carrier generation layer) having a B ratio (referring to the content ratio of a carrier generation substance to a binder substance (carrier generation substance/binder substance); the same applies hereinafter) was prepared.

However, for photoreceptors G and H in Examples, CTM (carrier transport material) having the following structural formula (TV) was added to the CGL coating liquid.
10g was added.

Next, the CGL coating liquid is applied using a doctor blade onto a conductive support made of polyethylene terephthalate having a thickness of about 75 μm and coated with aluminum.
A carrier generation layer having a predetermined thickness was formed.

Furthermore, 11.25 g of a predetermined carrier transport substance and 15 g of a predetermined binder resin were added to 10 g of 1,2-dichloroethane.
The resulting solution was applied onto the carrier generation layer using a doctor blade and heated at a temperature of 90°C for 1 hour.
A carrier transport layer was formed by drying for a period of time.

Here, in photoreceptors G and H, a carrier transport substance is added to the carrier generation layer. In addition, in each photoreceptor, the carrier transport substance in the coating solution is diffused into the carrier generation layer when the carrier transport layer is formed, so that the carrier transport substance is contained in the carrier generation layer (however, Regarding photoreceptor d, there is no such diffusion and no carrier transport substance is contained in the carrier generation layer).

As described above, each of the photoreceptors A to L and a
k was manufactured.

That is, in each photoreceptor, the content of the resin in the carrier generation layer, the P/B ratio, the film thickness, the carrier transport material used in the carrier transport layer, the binder material, and the film thickness of the photosensitive layer vary from each other. I'm forced to.

The composition and prescription of each photoreceptor are shown in Table 1 below.

Table 1 *No carrier transport substance in the carrier generation layer - The binder of the carrier generation layer is polyvinyl butyral (insoluble in the solvent for the carrier transport layer), and the solvent is tetrahydrofuran.

Structural formula [■] : [1°] : [■] : [■] : Tongue 2H5 [■] : Binder substance [Y] : Polycarbonate resin "Panlite 11300J (manufactured by Kijin Kasei Co., Ltd.) Binder substance [Z] Each of the 21 kinds of photoreceptors, including photoreceptors A-L according to the present invention and comparative photoreceptors a to 1, was subjected to rKON I CAL.
P3005J (manufactured by Konishiroku Photo Industry Co., Ltd.) (LD-equipped printer) installed in a modified machine, ■Yakaichi 600±10
(V), and reverse development is performed with a developing bias of -480 (V) to increase the image density of the black spots in the white area of the copied image and the black area (corresponding to the white area of the original image). , □ were evaluated.

In addition, the evaluation of Kuropochi was performed using the image analysis device "Omnicon 30".
00 type" (manufactured by Kinsei Seisakusho Co., Ltd.) to measure the particle size and number of black spots, and the black spots with a diameter of 0.05 or more were found to be l.
Judgment was made based on the number of pieces per CD.

The criteria for black spot evaluation are as shown in Table-2.

Table 2 Note that if the black spot determination result is ◎, ○, or Δ, it is practical, but if it is ×, it is not suitable for practical use.

Further, D and □ were marked as ◯ when they were 1.3 or more, and marked as × when they were 1.3 or less. Regarding moire, ○ represents the absence of moire, and × represents the occurrence of moire.

The results of black spot evaluation, D□, and the presence or absence of moiré on each photoreceptor are shown in Table 3 below.

(Margin below, continued on next page) Table-3 *No carrier transport material is added to the carrier generation layer.

As described above, based on the present invention, the photoreceptors A-L are used.
:tl has a P/B ratio ≦1/2, CGLrg, 21 μm1, and the carrier generating substance is a cyanine compound (pigment), so there are few black spots, no moiré, and D I
The photoreceptor properties were also good with IaM≧1.3.

On the other hand, the photoconductors i and i of the comparative example both have a PZB ratio of 1.
/2, the CGL film thickness is too small, resulting in many black spots (and moiré). Photoreceptor e %
Since h is P/B ratio > 1/2, there are many black spots regardless of the thickness of the CGL film.For photoconductor a, the P/B ratio is 115 and there are no black spots. Although there are few,
Moiré occurs because the film thickness of the CGL is too small, and the absolute amount of the carrier-generating substance in the CGL is insufficient, resulting in an increase in 1VLl and a decrease in D□, resulting in poor photoreceptor characteristics. That is, ■1 is the potential of the maximum exposure part, the potential of the part corresponding to the white background part of the original image, and IV Ll
An increase in D means a decrease in the sensitivity of the electrophotographic photoreceptor, which deteriorates developability and reduces image density.
This is because mmx has become smaller. Photoreceptor C is D
l*aK is small, and photoreceptor d has a P/B ratio and CGL
Even if the film thickness is sufficient, the CGL does not contain a carrier transport substance, resulting in poor sensitivity and insufficient concentration. photoreceptor j,
has no sensitivity to semiconductor lasers.

Example 2 and Example 2 Example 1 (or Comparative Example 1) under the conditions shown in Table 4 below.
Reverse development was performed in the same manner as above, and black spots, image density, carrier adhesion, and fog were observed. However, in the table, ◯ indicates no carrier adhesion, and × indicates occurrence of carrier adhesion.

(Margin below, continued on next page) Table-4 From this result, the following is clear.

For photoreceptor I: If lv, l < 500V, the image density is insufficient.

tv ol -1v-> 200V Teha+ + IJ
Adhesion occurred.

1vl (l-1vDcl<0■ Cuffing occurs on the entire surface.

For photoconductor: Black spots occur.

[Brief explanation of the drawing]

Figures 1 to 3 show embodiments of the present invention. Figures 1 and 2 are cross-sectional views of each side of the photoreceptor used in the present invention, and Figure 3 is a cross-sectional view of the image forming apparatus. FIG. 4 is a schematic diagram of the configuration of a laser beam scanner for image exposure, FIG. 5 is a sectional view of essential parts of a developing device, and FIG. 6 is a flowchart showing the process of image formation. 7, 8, and 9 are sectional views of each side of a conventionally used photoreceptor. In addition, in the symbols shown in the drawings, 1... Conductive substrate 2.6... Carrier generation layer (CC; L) 3...
... Undercoat layer 4 ... Carrier transport layer (CTL) 5.8...
・Photosensitive layer 10...Carrier generating substance (CGM) 12...
... Fixing device 13 ... Static eliminator 14 ... Cleaning device 15 ... Developing device 20 ... Pre-transfer exposure lamp 21 ... Transfer device 22 ... Charger 23 ... Image carrier 41 ... Laser 43 ... Mirror scanner 44 ... Imaging f-theta lens 48, 49 ... Cylindrical lens 51 ... Laser beam 61 ... Developing sleeve 62... Magnet 63... Layer thickness regulating blade 69... Bias power supply 70... Protection resistor. Agent Patent Attorney Hiroshi Aisaka Figure 1 Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. An image forming method using a photoreceptor in which a carrier transport layer is provided on a carrier generation layer containing a carrier generation substance and a binder substance, (a) the photoreceptor includes: The carrier generating substance in the carrier generating layer is made of at least a cyanine compound, and the content ratio of the carrier generating substance to the binder substance (carrier generating substance/binder substance) is 1.
/2 or less, the carrier generation layer has a film thickness of 1 μm or more, and the carrier generation layer also contains a carrier transport substance, (b) using a photoconductor containing a semiconductor An electrostatic latent image having an absolute value of the highest electric potential of 500 V to 900 V is formed by irradiation with laser light, and then an absolute value of 0 to 200 V lower than the absolute value of the highest electric potential of the electric charge forming the electrostatic latent image is formed. An image forming method characterized in that the electrostatic latent image is reversely developed by applying a DC bias voltage having a certain value.