JP2003195576A - Initial setting method of electrostatic charging condition in electrophotographic device using organic single-layer photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which makes it possible to initially set electrostatic charging conditions when an initial photoreceptor is loaded in a device very easily and automatically when an image is formed by an electrophotographic device by using an organic single-layer photoreceptor. <P>SOLUTION: The initial setting method of electrostatic charging condition is characterized in that, when image formation is performed by electrophotography by using the organic single-layer photoreceptor, a dark potential (reference dark potential) and a light potential (reference light potential) when the surface of the photoreceptor is electrostatically charged to a fixed reference electrostatic charging potential are measured as to the initial photoreceptor and information on them are stored in the electrophotographic device, and the initial photoreceptor is loaded in the electrophotographic device, the photoreceptor surface is charged to an electrostatic charging potential different from the reference electrostatic charging potential, and a dark potential and a light potential are measured; and values αand β are calculated from Vr=αVo+β, where Vo is the dark potential, Vr is the light potential (V), and α and β are constants, according to information on the stored reference-time dark potential and reference light potential and electrostatic charging conditions are initially set according to a straight line Vo-Vr determined according to the calculation results so that a contrast potential (Vc) corresponding to the difference between the dark potential and light potential has a proper value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a charging condition in an electrophotographic apparatus using an organic single layer photoreceptor, more specifically, an organic single layer photoreceptor is attached to the electrophotographic apparatus. The present invention relates to a setting method capable of easily performing the initial setting of the charging condition in such a case.

[0002]

2. Description of the Related Art In image formation by electrophotography, reversal development is currently the mainstream. According to this reversal development, after uniformly charging a photoconductor, a laser beam or the like is applied based on predetermined image information. The image is exposed to form an electrostatic latent image, the electrostatic latent image is developed with toner, the toner image is transferred from the photoconductor to the transfer paper, and the toner image on the transfer paper is fixed to form the image. Let it form.

As a photoreceptor used in such image formation, an inorganic photoreceptor such as selenium or amorphous silicon, or an organic photosensitive layer containing a charge generating agent or a charge transporting agent is formed on a conductive substrate. Organic photoconductors are known, and in particular, the organic photoconductors are excellent in lightness and cost, and are currently widely used. The organic photoconductors include a single-layer type (organic single-layer photoconductor) in which a charge generating agent and a charge transporting agent are dispersed in a single organic photosensitive layer, and a charge in which the charge generating agent is dispersed. There is known a laminated type (organic laminated photoreceptor) in which an organic photosensitive layer is formed from a generation layer and a charge transport layer formed on the charge generation layer and having a charge transport agent dispersed therein. Among them, the organic single-layer photoconductor is currently widely used because it is particularly easy to manufacture and is extremely inexpensive in terms of cost.

[0004]

By the way, when the photoconductor is charged to a constant potential, the surface potential of the light-irradiated portion by image exposure is attenuated, and the portion not irradiated with light is darkly attenuated. Therefore, for example, when image formation is performed by reversal development, the light attenuating portion is the image portion (toner adhering portion).
And the dark decay part corresponds to the non-image part (background where toner does not adhere), so the contrast equivalent to the difference between the potential of the dark decay part (dark potential) and the potential of the light decay part (bright potential). The charging conditions must be set so that the electric potential (Vc) has an appropriate value. If the contrast potential (difference between the dark potential and the bright potential) is too small, the contrast of the image is small and the image becomes unclear, or a high-density image cannot be obtained. If the contrast potential is too large, This is because development by the carrier in the developer is performed, and inconveniences such as toner scattering occur.

Therefore, in the manufacturing process of an electrophotographic apparatus, when the photoconductor is attached to the apparatus or a commercially available electrophotographic apparatus is repeatedly used, the life of the photoconductor is exhausted,
When the photoconductor is replaced with a new photoconductor, it is necessary to set the charging conditions as described above. Conventionally, the setting of the charging condition as described above is performed after the photoconductor is mounted on the device,
Various changes to the charging conditions of the charger for main charging,
Each time, an image is actually formed, and the image obtained is checked, so that there is a problem that the work is extremely troublesome. In particular, in a commercially available electrophotographic apparatus, it is very difficult for a general user to set the photoconductor when replacing the photoconductor. Even if a service person performs the setting, the setting is extremely troublesome, the burden on the service person is large, and improvement thereof is required.

Further, in the organic single-layer photoconductor, even if compared with other photoconductors, the influence of the thickness of the photoconductor layer on the image is great, and it is particularly difficult to set the charging condition by uniform work. There is a problem.

Therefore, an object of the present invention is to provide an electrophotographic apparatus in which an organic single-layer photoconductor is used among various photoconductors, in which an initial photoconductor on which an image is not formed is formed very easily and automatically. An object of the present invention is to provide a method capable of performing initial setting of charging conditions when mounted.

[0008]

That is, according to the present invention,
An organic single-layer photoreceptor having a single-layer organic photosensitive layer is used, the surface of the organic single-layer photoreceptor is uniformly main-charged, and the charged surface of the photoreceptor is irradiated with light based on image information to be electrostatically charged. In an electrophotographic apparatus for forming an image by forming a latent image and developing the electrostatic latent image while applying a constant developing bias voltage, a photoconductor is previously prepared with a constant reference charging potential for an initial photoconductor. Measure the dark potential (reference dark potential) and bright potential (reference bright potential) when the surface is charged,
This information is stored in the electrophotographic apparatus, and then the initial photoconductor is mounted on the electrophotographic apparatus, and the surface of the photoconductor is
The dark potential and the bright potential are measured by charging to a charging potential different from the reference charging potential, and based on the measurement result and the information of the reference dark potential and the reference bright potential stored in the above, the following formula ( 1): Vr = α · Vo + β (1) In the formula, Vo represents a dark potential (V), Vr represents a bright potential (V), and α and β represent constants. Is calculated so that the contrast potential (Vc) corresponding to the difference between the dark potential and the bright potential becomes an appropriate value based on the Vo-Vr straight line of the formula (1) defined from the calculation result. There is provided a method for initializing charging conditions, which comprises initializing charging conditions.

When an image is formed by the electrophotographic method, as described above, the surface of the photoconductor is uniformly and main charged to a predetermined potential, and in this state, light irradiation is performed based on the image information, and electrostatic charging is performed. Form a latent image. That is, the potential of a portion irradiated with light decreases (bright potential), while the potential of a portion not irradiated with light hardly decreases (dark potential), and the potential difference between the dark potential and the bright potential causes the image information to be changed. A corresponding charge image (electrostatic latent image) is formed. Therefore, for example, in the currently widely used reversal development method, by supplying the developer (toner) charged to the same polarity as the main charging polarity to the surface of the photoconductor, the toner is applied to the light-irradiated portion having a low potential. A toner image that adheres and becomes a visible image is formed, and a portion not irradiated with light serves as a background of the image. The so-called regular developing method is the reverse of this, in which toner charged to a polarity opposite to the main charging polarity is used, and the charged toner adheres to the high-potential light-unirradiated portion to form a toner image, The low light exposure area becomes the background of the image. As can be understood from this, the difference between the dark potential and the bright potential becomes the contrast potential (Vc) corresponding to the contrast of the image in either the reversal development or the normal development. Therefore, in order to obtain an image having a constant density, it is necessary to secure a constant contrast potential (Vc).

According to the present invention, in an organic single-layer photosensitive member having a constant photosensitive layer thickness, when the image exposure condition (for example, the output of a laser used for light irradiation) is constant, the dark potential and the bright potential are proportional to each other. It was made based on the new knowledge that the relationship is established. That is, please refer to the graph of FIG. 2 showing the experimental results in the experimental example described later. FIG. 2 shows that the charging voltage is changed for each thickness of the photosensitive layer of the organic single-layer photoconductor,
It shows a curve in which the bright potential is plotted against the dark potential. (For example, after the dark potential is measured, charging is performed under the same conditions, then the laser light irradiation is performed to measure the bright potential, and the laser light irradiation is performed at the same output.) From FIG. As is clear, at least in a region having an effective photosensitive layer thickness that does not cause charge leakage,
It can be seen that the bright potential is proportional to the dark potential for each film thickness, and there is a linear relationship between the two. That is, for a single-layer organic photosensitive layer having a certain thickness, the relationship represented by the above formula (1) is established.

The relationship between such a bright potential and a dark potential has not been known at all in the past, and is a novel finding first found by the present inventors. Moreover, such a relationship is peculiar to the organic single-layer photoconductor, and for example, in the organic laminated photoconductor, such a linear relationship is not established. The reason why the above linear relationship between the bright potential and the dark potential is peculiar to the organic single layer photoreceptor has not been clarified exactly. However, in the organic single-layer photoconductor, since the charge generating agent is uniformly dispersed in the photosensitive layer, the amount of the charge generating agent is proportional to the thickness of the photosensitive layer. It is divided into a charge generation layer below and a charge transport layer on the surface side, and there is no proportional relationship between the thickness of the photosensitive layer and the amount of charge generation agent. Although a linear relationship is established with the electric potential, it is considered that this is one of the reasons why the linear relationship is not established between the two in the organic laminated photoreceptor.

Therefore, in the present invention, the charging condition is initially set by utilizing the above-described linear relationship between the bright potential and the dark potential. That is, with respect to an unused organic single-layer photoconductor (initial photoconductor), a dark potential (reference dark potential) and a bright potential (reference bright potential) when the surface of the photoconductor is charged with a constant reference charging potential in advance. Is measured and this information is stored in the electrophotographic apparatus on which the photoconductor is mounted. Next, the initial photoconductor is mounted on an electrophotographic apparatus, main charging is performed under a charging condition different from the reference potential, and the dark potential and the bright potential are measured. From the measurement result and the information stored in advance, the constants α and β can be calculated from the equation (1) with respect to the mounted initial photoconductor, and thus Vo of the equation (1) can be calculated. A −Vr straight line can be defined.

For example, the stored reference dark potential is Vo
1. If the measured dark potential is Vo2, the stored reference bright potential is Vr1, and the measured bright potential is Vr2, these are substituted into the equation (1), and the following relational expression (1
a) and (1b) are obtained. Vr1 = α · Vo1 + β (1a) Vr2 = α · Vo2 + β (1b) By solving this simultaneous equation, the values of α and β can be obtained. α = (Vr2-Vr1) / (Vo2-Vo1) (2a) β = (Vr1Vo2-Vo1Vr2) / (Vo2-Vo1) (2b) Therefore, the formula (1) in the organic single-layer photoconductor in this state.
Vo-Vr straight line can be defined.

On the other hand, an appropriate value of the contrast potential (Vc) is set in advance so that an appropriate image can be obtained.
If this proper value is stored in the electrophotographic apparatus, the dark potential giving such a proper value of the contrast potential (Vc) is automatically calculated by using the Vo-Vr straight line of the equation (1) defined above. Can be calculated. That is, the contrast potential (Vc) is represented by the following formula (3): Vc = Vo-Vr (3) where Vo represents a dark potential (V) and Vr represents a bright potential (V). Therefore, in the defined formula (1),
By substituting the equation (3), it is possible to obtain a dark potential that gives a proper value of the preset contrast potential (Vc).

For example, when such a dark potential is Voc, from the formula (3) and the defined formula (1), the following formula (4) is obtained.
Is established. Vc = Voc- (α · Voc + β) (4) In the formula, α and β are constants that satisfy the formulas (2a) and (2b). Therefore, when the dark potential (Voc) that gives an appropriate value of the contrast potential (Vc) is obtained from the equation (4), the following equation (5) is obtained. Voc = (Vc + β) / (1-α) (5)

Thus, according to the present invention, by initializing the charging conditions so as to satisfy the above formula (5), no matter what thickness the photosensitive layer of the initial photoreceptor has, A clear image can be obtained with proper density.

Since such an initial setting method of the present invention utilizes the fact that the linear relationship shown in the equation (1) is established between the bright potential and the dark potential, the organic single layer photoreceptor is It is applied only to the electrophotographic method used, and is not applied to the case where the organic laminated photoreceptor in which the above linear relationship is not established is used.

In the present invention, the initial setting of the charging condition that satisfies the above formula (5) can be easily performed depending on the type of the main charger used. For example, when the main charging is performed using the scorotron charger, the grid voltage of the scorotron charger may be adjusted, and when the main charging is performed using the contact charging roller, the voltage applied to this charging roller may be adjusted. Adjust it. Further, in the operation of measuring the dark potential and the bright potential by charging the initial photoconductor to a potential different from the reference potential, such operating conditions are programmed in advance, and the operation of the image exposure unit and the development unit is performed. This can be automatically performed by providing a potential sensor in the region between and turning on a setting switch provided on the operation panel of the device. Further, the calculation of α and β based on the measurement result and the stored information (definition of the straight line of the formula (1)) and the calculation of the dark potential (Voc) based on the defined straight line of the formula (1), It can also be automatically performed by incorporating a predetermined arithmetic program. Therefore, according to the present invention, not only can the initial setting of the charging conditions when the initial photoconductor is attached to the apparatus in the manufacturing process can be extremely easily performed, but also the photoconductor of the commercially available electrophotographic apparatus can be replaced. Even when the initial setting of the charging condition is performed, the setting work can be easily performed, and the labor of the service person can be remarkably reduced. In addition, in some cases, such an initial setting can be easily performed by a general user.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on specific examples shown in the accompanying drawings. In FIG. 1, which shows an example of an electrophotographic apparatus to which the initial setting method of the charging condition of the present invention is applied, around the photosensitive drum 1 which is rotatably provided, a charging unit 2 is provided along the rotation direction thereof. A laser optical device 3, a developing unit 4, a transfer unit 5, a cleaning unit 6 and a charge eliminating lamp 7 are arranged, and a transfer sheet 9 such as a predetermined paper is conveyed between the transfer unit 5 and the photosensitive drum 2. An image is formed on the surface of the transfer sheet 9. Further, a potential sensor 10 is provided between the laser optical device 3 and the developing means 4, and although not shown in FIG. 1, the discharge side of the transfer sheet 9 is provided with a heat roller or the like. The fixing device is arranged.

That is, the entire surface of the photosensitive drum 1 is main-charged uniformly to a predetermined polarity by the charging means 2, and then the laser beam is charged by the laser optical device 3 based on predetermined image information. The surface of the photosensitive drum 1 is irradiated with the light, and an electrostatic latent image is formed by image exposure. The electrostatic latent image thus formed is developed by the developing means 4, and a toner image is formed on the surface of the photosensitive drum 1. The formed toner image is transferred onto the surface of the transfer sheet 9 by the transfer unit 5, and the transfer sheet 9 onto which the toner image has been transferred is introduced into a fixing device (not shown), and by heat and pressure,
The toner image is fixed on the surface of the transfer sheet 9. On the other hand, after the toner image is transferred to the transfer sheet 9, the cleaning device 6 removes the toner remaining on the surface of the photoconductor drum 1, and the light remaining on the surface of the photoconductor drum 1 is removed by the light irradiation by the charge eliminating lamp. It is removed, which completes one step of the image forming cycle and the next image forming cycle is performed.

In the present invention, the photosensitive drum 1 is an organic photosensitive drum formed on a conductive tube made of aluminum or the like, and this organic photosensitive layer is known per se and includes a charge generating agent and a charge transporting material. It consists of a single layer in which the agent is dispersed in a binder resin. That is, in the photoconductor drum 1 provided with such a single-layer organic photosensitive layer, the linear relationship shown in the above-described formula (1) is established between the bright potential and the dark potential, and the initial setting method of the present invention is performed. The application is as described above.

Examples of the charge generating agent dispersed in the photosensitive layer include selenium, selenium-tellurium, amorphous silicon, pyrylium salt, azo pigments, disazo pigments, ansanthuron pigments, phthalocyanine pigments and indico pigments. Examples thereof include threnic pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments and the like, and they may be used alone or in combination of two or more so as to have an absorption wavelength region in a desired region.

The following are examples of particularly suitable charge generating agents. X-type metal-free phthalocyanine. Oxotitanyl phthalocyanine.

Perylene pigments, especially those of general formula (A),

[Chemical 1] In the formula, each of R ₁ and R ₂ is a substituted or unsubstituted alkyl group having 18 or less carbon atoms, a cycloalkyl group, an aryl group, an alkaryl group, or an aralkyl group. In the general formula (A), examples of the alkyl group include an ethyl group, propyl group, butyl group, and 2-ethylhexyl group, examples of the cycloalkyl group include a cyclohexyl group, and examples of the aryl group include phenyl. Group, naphthyl group, etc., alkaryl group, tolyl group, xylyl group, ethylphenyl group, etc., and aralkyl group, benzyl group, phenethyl group, etc. Examples of the substituent include an alkoxy group and a halogen atom.

Bisazo pigments, especially the following general formula (B)

[Chemical 2] In the formula, A is a hydrogen atom or a substituted or unsubstituted alkyl group, aryl group or heterocyclic group, n is zero or 1, and Cp is a coupler residue. In the above general formula (B), a substituted or unsubstituted alkyl group, an aryl group or a heterocyclic group may be bonded to the 3-position of the pyrazole ring directly or via a vinylidene group. As a basis,
Examples thereof include methyl, ethyl, propyl, butyl, amyl groups, etc., examples of aryl groups include phenyl, naphthyl, biphenyl, anthryl, phenanthryl, fluorenyl groups, etc., and examples of heterocyclic groups include nitrogen, oxygen, sulfur and the like. A monocyclic or polycyclic saturated or unsaturated heterocyclic group containing a combination in the ring, for example, a thienyl group, a furyl group, an imidazolyl group, a pyrrolyl group, a pyrimidinyl group,
Imidazole group, pyrazinyl group, pyrazolinyl group, pyrrolidinyl group, pyranyl group, piperidyl group, piperazinyl group, morpholyl group, pyridyl group, pyrimidyl group, pyrrolidinyl group, pyrrolinyl group, benzofuryl group, benzimidazolyl group, benzofuranyl group, indolyl group, quinolyl group , Carbazolyl group, dibenzofuranyl group and the like. As the substituent which these groups may have,
Lower alkyl group, lower alkoxy group, acyloxy group,
Halogen atom such as chlor, hydroxyl group, nitrile group, nitro group, amino group, amide group, acyloxy group,
Examples thereof include a carboxyl group. On the other hand, the coupler residue in the formula (B) is arbitrary as long as it is a residue of a coupler (azo coupling component) used in this type of azo pigment, for example, substituted or unsubstituted phenols and naphthols. Alternatively, it may be a hydroxyl group-containing heterocyclic compound or the like, and the substituent here is a lower alkyl group, a lower alkoxy group, an aryl group, an acyloxy group, a halogen atom such as chlor, a hydroxyl group, a nitrile group, a nitro group, Examples thereof include an amino group, an amide group, an acyloxy group and a carboxyl group.

Various resins can be used as the resin medium (binder resin) in which the charge generating agent is dispersed. Examples of the resin medium include styrene-based polymers, acrylic-based polymers, and styrene-based polymers.
Acrylic polymer, ethylene-vinyl acetate copolymer, polypropylene, olefin polymer such as ionomer,
Polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, Examples include various polymers such as a phenol resin and a photocurable resin such as epoxy acrylate. These binder resins may be used alone or in combination of two or more. Suitable resins are styrene polymers, acrylic polymers, styrene-acrylic polymers, polyesters, alkyd resins, polycarbonates, polyarylates and the like.

Preferred resins are polycarbonate,
Especially, Teijin Kasei's Panlite and Mitsubishi Gas Chemical's PC
Z, Idemitsu Kosan Co., Ltd. Tuffet (B grade or H grade), etc., the following general formula (C):

[Chemical 3] In the formula, R ₃ and R ₄ are a hydrogen atom or a lower alkyl group, and R ₃ and R ₄ may be linked to each other to form a cyclo ring such as a cyclohexane ring together with the bonding carbon atom. There may be mentioned a polycarbonate containing a constitutional unit derived from bisphenol and phosgene.

Considering the wear resistance, the following general formula (D):

[Chemical 4] In the formula, R represents a hydrogen atom or a substituted or unsubstituted alkyl group having 18 or less carbon atoms, a cycloalkyl group, an aryl group, an alkaryl group, or an aralkyl group, and p
And q are numbers showing a copolymerization ratio, and when p + q = 1, a copolymerized polycarbonate having a structure represented by p is a number such that p is 0.1 to 0.4.

The molecular weight of the binder resin is the viscosity average molecular weight (PC
It is preferably 10,000 to 200,000 in terms of -A), but considering abrasion resistance and productivity, it is 18,000 to 8
10,000 is especially preferred. Further, the proportion of the binder resin in the photosensitive layer is preferably 40 to 70% by weight, but if a copolymerized polycarbonate having the structure of the general formula (D) is used to improve abrasion resistance, A range of 50 to 70% by weight is suitable.

As the charge transfer agent, any known electron transfer or hole transfer agent can be used. A suitable example is as follows.

Examples of the electron transfer agent include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, and 3
-Nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanoquinodimethane, chloranil, Bromoanil, o-nitrobenzoic acid, malononitrile, trinitrofluorenone, trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, thiopyran compounds, quinone compounds, benzoquinone compounds, diphenoquinone compounds, naphthoquinone An electron-withdrawing substance such as a compound, an anthraquinone compound, or a stilbenequinone compound can be used alone or in combination of two or more.

The following can be exemplified as particularly preferable ones.

The following general formula (E):

[Chemical 5] In the formula, R ^a represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and R ^b represents an alkyl group which may have a substituent or a substituent. Represents an aryl group or a group -O-RG. The naphthoquinone represented by R G in the group represents an alkyl group which may have a substituent or an aryl group which may have a substituent.

The following general formula (F):

[Chemical 6] In the formula, each of R ⁵ , R ⁶ , R ^7, and R ⁸ is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, or the like. R ⁵ , R ⁶ , R ⁷ and R ⁸ are preferably substituents having an asymmetric structure, and among R ⁵ , R ⁶ , R ⁷ and R ⁸ ,
It is preferable that two are lower alkyl groups and the other two are branched chain alkyl groups, cycloalkyl groups, aryl groups or aralkyl groups.

Suitable examples of the diphenoquinone derivative are:
Without limitation, 3,5-dimethyl-3 ', 5'
-Di-t-butyldiphenoquinone, 3,5-dimethoxy-3 ', 5'-di-t-butyldiphenoquinone, 3,3'
-Dimethyl-5,5'-di-t-butyldiphenoquinone,
3,5'-dimethyl-3 ', 5-di-t-butyldiphenoquinone, 3,5,3', 5'-tetramethyldiphenoquinone, 2,6,2 ', 6'-tetra-t-butyl Examples thereof include diphenoquinone, 3,5,3 ′, 5′-tetraphenyldiphenoquinone, 3,5,3 ′, 5′-tetracyclohexyldiphenoquinone, and the like. These diphenoquinone derivatives are preferable because they have low symmetry of molecules and thus have small interaction between molecules and excellent solubility.

The following general formula (G):

[Chemical 7] In the formula, Rs may be the same or different and each is a hydrogen atom,
A diphenoquinone represented by a C1 to C12 alkyl group, a C1 to C12 alkoxy group, an aryl group which may have a substituent, a cycloalkyl group, an aralkyl group and a halogenated alkyl group. . Examples of the substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, an amino group, a nitro group, and a halogenated alkyl group.

The following general formula (H):

[Chemical 8] In the formula, Rs may be the same or different and each is a hydrogen atom,
A naphthoquinone represented by a C1-12 alkyl group, a C1-12 alkoxy group, an aryl group which may have a substituent, a cycloalkyl group, an aralkyl group, and a halogenated alkyl group. . As the substituent, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, an amino group,
Examples thereof include nitro group and halogenated alkyl group.

The following general formula (J):

[Chemical 9] In the formula, Rs may be the same or different and each is a hydrogen atom,
An alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group which may have a substituent, a cycloalkyl group, an aralkyl group and a halogenated alkyl group, respectively, and X is the same Which may be different, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group which may have a substituent, respectively,
A stilbene represented by a cycloalkyl group, an aralkyl group, a phenoxy group, and a halogenated alkyl group, which may be condensed with each other to form a ring, and n is an integer of 0 to 5. Quinon.

On the other hand, as the hole transporting substance, for example, the following substances are known, and among them, those having excellent solubility and hole transporting property are used. Pyrene; N-
Ethylcarbazole, N-isopropylcarbazole,
N-methyl-N-phenylhydrazino-3-methylidene-9-carbazole, N, N-diphenylhydrazino-
Carbazoles such as 3-methylidene-9-ethylcarbazole; N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine; N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine; p -Diethylaminobenzaldehyde-N,
N-diphenylhydrazone, p-diethylaminobenzaldehyde-α-naphthyl-N-phenylhydrazone,
p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω
Hydrazone salts such as -aldehyde-N, N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone; 2,5-bis (p-diethylaminophenyl) -1,3,4- Oxazizole; 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinonyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) ) Pyrazoline, 1- [pyridyl (2)]-3- (p-
Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [6-methoxy-pyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[Lepidyl (3)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -4-methyl-5 -(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3-
(Α-Methyl-p-diethylaminostyryl) -3-
(P-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminoffer) pyrazoline,
Pyrazolines such as spiropyrazoline; 2- (p-diethylaminostyryl) -3-diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4
An oxazole-based compound such as-(p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole; a thiazole-based compound such as 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole;
Triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) phenylmethane; 1,1
-Bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,2,2-tetrakis (4-
Polyarylalkanes such as N, N-dimethylamino-2-methylphenyl) ethane; N, N′-diphenyl-N, N′-bis (methylphenyl) benzidine,
N, N'-diphenyl-N, N'-bis (ethylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (propylphenyl) benzidine, N, N'-diphenyl-N, N'- Bis (butylphenyl) benzidine,
N, N'-bis (isopropylphenyl) benzidine,
N, N'-diphenyl-N, N'-bis (secondary butylphenyl) benzidine, N, N'-diphenyl-N, N
′ -Bis (tertiary butylphenyl) benzidine, N, N
′ -Diphenyl-N, N′-bis (2,4-dimethylphenyl) benzidine, N, N′-diphenyl-N, N ′
A benzidine compound such as bis (chlorophenyl) benzidine; a phenylenediamine derivative; a diaminonaphthalene derivative; a diaminophenanthrene derivative; triphenylamine; poly-N-vinylcarbazole; polyvinylpyrene; polyvinylanthracene; Phenylanthracene; pyrene-formaldehyde resin; ethylcarbazole formaldehyde resin.

Preferred examples of the hole transfer material include the following formula (K):

[Chemical 10] In the formula, each of Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ is a substituted or unsubstituted aryl group, Y is a substituted or unsubstituted arylene group, and n is a number of 0 or 1. The aromatic amines represented may be mentioned.

Further, other preferable examples of the hole transfer agent include hydrazones, especially the following formula (L):

[Chemical 11] In the formula, each of Ar ₅ , Ar ₆ and Ar ₇ may be a hydrazone represented by a substituted or unsubstituted aryl group.

A hole transfer material having a structure represented by the following formula (M) has high mobility and is suitable.

[Chemical 12] In the formula, Rs may be the same or different and each is a hydrogen atom,
A C1-C8 alkyl group and a C1-C8 alkoxy group are shown, and each benzene ring has a C1-C8 alkyl group and a C1-C8 alkoxy group as a substituent. You can do it.

In the above single-layer organic photosensitive layer, the charge generating agent (CGM) is 0.5 to 7% by weight based on the solid content,
In particular, it is preferable that the photosensitive layer is contained in the photosensitive layer in an amount as small as possible within the range of 2 to 5% by weight so long as the sensitivity is not adversely affected.
To 70% by weight, especially 25 to 60% by weight,
It is preferable that the photosensitive layer is contained in an amount as small as possible within the range that does not affect the sensitivity.

From the viewpoint of sensitivity and versatility of enabling reversal development, it is preferable to use a combination of an electron transfer agent (ET) and a hole transfer agent (HT). In this case, the ET: HT weight ratio is 10: 1 to 1:10,
In particular, the range of 1: 5 to 1: 1 is the best.

In the above single-layer organic photosensitive layer, various compounding agents known per se, such as biphenyl, o-terphenyl, m-, etc., are used within a range that does not adversely affect electrophotographic characteristics. Biphenol derivatives such as terphenyl, p-terphenyl, p-benzylphenyl and hydrogenated terphenyl, alkyl esters such as butyl stearate,
Polyethylene glycol, polypropylene glycol,
Contains polyethylene glycol monoester, polyethylene glycol monoether, polyethylene glycol dialkylate, polyalkyl oxides such as polyethylene glycol dialkyl ether, plasticizers such as polyphenylene oxide, lubricants, and antioxidants such as hindered amines and hindered phenols. May be. Further, for the purpose of improving the leveling property of the formed film and imparting lubricity, a leveling agent such as silicone oil or fluorine-based oil may be contained.

In particular, when 0.1 to 50% by weight of the total solid content of the sterically hindered phenolic antioxidant is added,
The durability of the photosensitive layer can be significantly improved without adversely affecting the electrophotographic characteristics.

As the conductive substrate on which the single-layer organic photosensitive layer is provided, various conductive materials can be used.
Single metals such as aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, indium, stainless steel, and brass, and plastic materials in which the above metals are vapor-deposited or laminated; aluminum iodide , Glass coated with tin oxide, indium oxide, or the like; and the like. In the single-layer organic photoconductor used in the present invention, a normal aluminum tube or an alumite-processed tube having a film thickness of 1 to 50 μm can be used.

In order to form a single-layer organic photoreceptor, a charge-generating material, a charge-transporting agent, etc. and a binder resin, etc. are prepared by a conventionally known method such as roll mill, ball mill, attritor, paint shaker or ultrasonic disperser. It may be prepared by using the above method, coated by a conventionally known coating means, and dried.
The thickness of the photosensitive layer is not particularly limited, but it is generally preferably in the range of 10 to 50 μm, and is preferably as thick as possible within the range that does not decrease the sensitivity or increase the residual potential.

As the solvent used for forming the coating solution, various organic solvents can be used. Alcohols such as methanol, ethanol, isopropanol and butanol,
Aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, Ethylene glycol dimethyl ether, ethers such as diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, ketones such as cyclohexanone, ethyl acetate, esters such as methyl acetate, dimethylformamide, dimethyl sulfoxide, etc. Used as a mixture. The solid content concentration of the coating liquid is generally preferably 5 to 50%.

The single-layer photosensitive layer may be formed directly on the conductive substrate, but may be formed via an undercoat layer. Examples of such an undercoat layer include polymer films of casein, polyvinyl alcohol, polyvinyl acetal, polyamide, melamine, cellulose, polythiophene, polypyrrole, polyaniline, polyester, polyacrylate, polystyrene and the like. The thickness of the undercoat layer is preferably in the range of 0.01 μm to 20 μm. Further, in order to impart conductivity to the undercoat layer, metal powder such as gold, silver and aluminum, metal oxide powder such as titanium oxide and tin oxide, and conductive fine powder such as carbon black can be dispersed.

As the charging means 2 for mainly charging the surface of the photosensitive drum 1, a corona charger such as a corotron or a scorotron or a contact charging roller is used, and a scorotron is particularly preferable. The charging polarity of the surface of the photoconductor drum 1 by the charging means may be either positive or negative, but from the viewpoint of preventing the generation of ozone and the like, the positive polarity is good.

Further, the main charging potential of the photosensitive drum 1 decreases when the main charging is carried out under the same conditions as the photosensitive layer wears due to repeated image forming cycles, but the initial setting value is the dark potential ( The contrast potential (Vc) corresponding to the difference between Vo) and the bright potential (Vr) is 400 V or more, especially 55.
Potential that becomes 0V or more, for example, 700 to 720V
It is set to the range of. That is, the contrast potential (Vc)
The charging conditions are initially set so that the above condition is within the above range. Specifically, when a corona charger is used as the charging means 2, by increasing the voltage applied to the corona wire or adjusting the grid voltage, and when using a contact charging roller,
By increasing the voltage applied to the roller, the main charging potential can be adjusted within an appropriate range. Especially the charging means 2
When a scorotron is used as the above, the potential can be easily adjusted by adjusting the grid voltage.

Image exposure using the laser optical device 3
It can be carried out by means known per se. For example, based on image information read by a scanner or the like, or based on image information sent from a computer or the like,
It is performed by irradiating laser light. Of course, instead of using the laser optical device 3 as described above, an LED or an optical system such as a halogen lamp is used to directly irradiate the surface of the photosensitive drum 1 with the reflected light of the document from such an optical system. It is also possible to perform image exposure by.

In the present invention, a potential sensor 10 is provided between the laser optical device 3 and the developing means 4,
When correcting the development conditions, the potential sensor 10
To measure the dark potential and the bright potential. The measurement point by the potential sensor 10 is the central portion of the surface of the photosensitive drum 1, that is, the portion corresponding to the image forming area. That is, the dark potential and the bright potential are measured by charging the surface of the photosensitive drum 1 to a potential different from the reference potential set when measuring the reference dark potential and the reference bright potential, and then irradiating light for image exposure. The dark potential is measured by the potential sensor 10 without performing the above, and then the surface of the photosensitive drum 1 charged to the same potential under the same conditions is subjected to the same conditions as the image exposure performed in a normal image forming cycle (for example, the same laser output ), And the bright potential is measured by the potential sensor 10. The light irradiation conditions for measuring the reference bright potential are also set to the same conditions as described above. Based on the above measured value and the stored reference dark potential and reference bright potential, the above-described calculation is performed to initialize the charging condition so that the contrast potential (Vc) becomes the appropriate value described above. The main charging of the surface of the photosensitive drum 1 is performed. The reference potential (main charging potential of the photosensitive member surface) when measuring the reference dark potential and the reference bright potential and the main charging potential of the photosensitive member surface when measuring the dark potential and the bright potential are mutually There is no particular limitation as long as they are different, but it is preferable that the difference between two different potentials is usually 100 V or more. This is because if the potential difference between the two is too small, the measurement error may increase.

The developing means 4 is known per se and, for example, a magnetic developer containing a toner charged to at least a predetermined polarity is conveyed to the surface of the photosensitive drum 1 by using a magnetic force by a developing roller. Done. Such a developer is also not particularly limited, and for example, either a two-component developer composed of a non-magnetic toner and a magnetic carrier such as ferrite or iron powder, or a one-component developer composed of a magnetic toner is used. be able to. The charging polarity of the toner differs depending on the developing method. For example, in the currently widely used reversal developing method, the charging polarity is the same as that of the photosensitive drum 1,
In the normal development method, the polarity is opposite to the charging polarity of the photoconductor drum 1, and normally, the toner is charged to have an appropriate charge amount by frictional charging with a predetermined charging member or carrier.

The development by the developing means 4 may be either contact development or non-contact development.
Usually, the developing bias voltage is applied between the photosensitive drum 1 and the developing roller. The developing bias voltage has a polarity and a magnitude that allows the charged toner to easily move to the surface side of the photosensitive drum 1. For example, in reversal development, the photosensitive drum 1 side has an opposite polarity to the charging polarity. And the absolute value is between the dark potential and the bright potential. Therefore, in the present invention, the developing bias voltage is set within the above range in accordance with the initial setting of the charging condition described above.

As the transfer means 5, a corona charger or a transfer roller is used. When using a corona charger,
This is performed by corona charging the back surface of the transferred transfer sheet 9 to a polarity opposite to that of the charged toner by corona discharge. In this case, the transfer sheet 9 is transferred to the photosensitive drum 1 together with a corona charger for transfer. It is better to use a separating charger that prevents wrapping. When a transfer roller is used, transfer is performed by applying a transfer voltage such that the roller has a potential having a polarity opposite to that of the charged toner.

The cleaning device 6 is provided with a blade or roller made of rubber such as polyurethane. By rubbing these on the surface of the photosensitive drum 1, the toner remaining on the surface of the photosensitive drum 1 after transfer is separated. Be recovered.
In addition, the static elimination lamp 7 irradiates the surface of the photosensitive drum 1 with light having a wavelength having a sensitivity to a single organic photosensitive layer formed on the surface of the photosensitive drum 1. To remove. In FIG. 1, this static elimination lamp 7
Is arranged on the downstream side with respect to the rotation direction of the photoconductor drum 1, but it may be arranged in the region between the cleaning device 6 and the transfer means 5.

[0059]

The present invention will be described in the following experimental examples.

Preparation of Photoreceptor: 5 parts by weight of X-type metal-free phthalocyanine as a charge generating agent and the following formula as a hole transferring material:

[Chemical 13] 40 parts by weight of the compound of Example 1, 40 parts by weight of 2-t-butylcarbonyl-3-phenyl-1,4-naphthoquinone as an electron transfer agent, and a binder of the following formula:

[Chemical 14] 100 parts by weight of the polycarbonate copolymer resin (viscosity average molecular weight in terms of PC-A: 50,000), and further 800 parts by weight of tetrahydrofuran as a solvent are mixed and dispersed in a ball mill for 50 hours to coat a single-layer type photosensitive layer. Prepare a solution and apply this coating solution to an aluminum tube (Φ: 78 mm)
After coating on the surface, it is dried with hot air at 100 ° C. for 60 minutes to give a film thickness of 12 μm, 14 μm, 16 μm, 20 μm.
m and 36 μm single-layer organic photoreceptors were prepared.

Each of the photoconductor drums produced as described above was mounted in a copying machine having a structure similar to that shown in FIG. 1 and equipped with a surface electrometer. A scorotron is used as the main charger. Using this device, the main charging potential was changed, and the dark potential and the bright potential were measured for each main charging potential.
The laser output during the measurement was constant. The result is shown in FIG. From the result of FIG. 2, in such a single-layer organic photoreceptor, the light potential and the dark potential are in a proportional relationship, and the formula (1): Vr = α · Vo + β (1) In the formula, Vo is a dark potential ( V), Vr represents a bright potential (V), and α and β represent constants, respectively.

Next, the thickness produced above is 36 μm.
The single-layer organic photosensitive drum of No. 1 was mounted on the above machine, the main charging potential (reference potential) was set to 800 V, and the reference dark potential and the reference bright potential were measured, and the following results were obtained. Standard dark potential: 700V Standard bright potential: 120V

Furthermore, the grid voltage of the scorotron was adjusted, the charging conditions were set so that the main charging potential was 690 V, and the dark potential and the bright potential were measured. The results were as follows. Dark potential: 590V Bright potential: 105V

From the above results, α and β in the equation (1) were calculated, and the following results were obtained. α: 0.136 β: 24.5 On the other hand, as a result of a separate test, it is known that 550 V is an appropriate value for the contrast potential for obtaining a good image with the above-mentioned photosensitive drum. From the defined straight line of the formula (1), it was found that the dark potential for obtaining such an appropriate value of the contrast potential (Vc) was 670V. Therefore, the grid voltage of the scorotron was adjusted, the main charging potential was set to 770 V, and the dark potential was corrected to the above value. Therefore, based on the above measurement and calculation results, when the charging conditions etc. were initially set to the following conditions and image formation was performed, the image density was
It was 1.43, and a clear image was obtained.

Charging conditions: Main charging potential: 770V Dark potential: 670V Contrast potential: 550V Development method: Reversal development Developer: Positively charged two-component developer Development bias voltage: 520V Peripheral speed of photoconductor drum: 290 mm / sec

[0066]

According to the present invention, in the organic single layer photoreceptor,
Utilizing the new finding that the dark potential and the bright potential are in a linear relationship (proportional relationship), the reference dark potential and the reference bright potential are measured in advance for the initial photoconductor with a predetermined reference potential, and this information is stored. Further, by mounting the initial photoconductor on an electrophotographic apparatus, charging the photoconductor to a potential different from the reference potential, and measuring the dark potential and the bright potential, the dark potential of the initial photoconductor- The charging conditions can be initialized so that a bright potential line is defined and a proper contrast potential is given. Therefore, in the present invention, the initial setting of the charging condition can be automatically and uniformly performed, and the initial setting of the charging condition when the unused initial photoconductor is mounted in the apparatus can be extremely easily performed. Therefore, the work in the manufacturing process of the apparatus can be facilitated, the labor of the service person when exchanging the photoconductor can be significantly reduced, and the general user can easily perform the initial setting of the charging condition. It is now possible to do it.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an electrophotographic apparatus to which a method of the present invention is applied.

FIG. 2 is a diagram showing a relationship between a bright potential and a dark potential in a single-layer organic photoconductor obtained in an experimental example.

Continued front page    (72) Inventor Kei Tanaka             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. (72) Inventor Yuki Hikosaka             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. (72) Inventor, Masamasa Watanabe             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. (72) Inventor Jun Higashi             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. (72) Takashi Nagashima, the inventor             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. F term (reference) 2H027 DA02 EA01 EC07 EC18                 2H068 AA08 AA31 FC02                 2H200 FA18 GA16 GA23 GA34 GA45                       GA56 GA59 GB02 HA02 HA12                       HA29 HA30 HB12 HB28 PA18                       PA24 PB04

Claims (3)

[Claims] 1. An organic single-layer photoreceptor having a single organic photosensitive layer is used, the surface of the organic single-layer photoreceptor is uniformly main-charged, and the charged surface of the photoreceptor is irradiated with light based on image information. To form an electrostatic latent image, and the electrostatic latent image is developed while applying a constant developing bias voltage to form an image. The dark potential (reference dark potential) and the bright potential (reference bright potential) when the surface of the photoconductor is charged with the charging potential are measured, and this information is stored in the electrophotographic apparatus. The body is attached to an electrophotographic apparatus, the surface of the photoconductor is charged to a charging potential different from the reference charging potential, and the dark potential and the bright potential are measured, and the measurement result and the reference stored in the above are stored. Based on the information on the dark potential and the reference bright potential, the following formula ( ): Vr = α · Vo + β (1) In the formula, Vo represents a dark potential (V), Vr represents a bright potential (V), and α and β represent constants, respectively. A value is calculated, and the contrast potential (Vc) corresponding to the difference between the dark potential and the bright potential becomes an appropriate value based on the Vo-Vr straight line of the formula (1) defined from the calculation result. An initial setting method for charging conditions, which is characterized by initializing charging conditions. 2. The main charging is performed by using a scorotron charger, and charging conditions are set so that an appropriate contrast potential (Vc) can be obtained by adjusting a grid voltage of the scorotron charger. Item 2. The initial setting method for charging conditions according to Item 1. 3. The initial setting method of charging conditions according to claim 1, wherein the proper value of the contrast potential (Vc) is set and stored in advance.