JP3161724B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

The present invention relates to an electrophotographic apparatus, and more particularly, to an electrophotographic apparatus capable of obtaining a high-quality hard copy with good tone reproducibility in a reversal development process.

[0002]

[Prior art]

In recent years, demand for electrophotographic printers such as laser beam printers, LED printers, and LCD printers as output devices for computers, word processors, and facsimile machines has been rapidly increasing, and at the same time, organic electrophotographic photoreceptors are mounted on these devices. Cases are very large.

An organic photoreceptor has a two-layer structure in which a charge generation layer and a charge transport layer are sequentially laminated for various reasons such as material selectivity latitude, durability, potential stability, high sensitivity, and high response. Those having a basic form are often used.

In an electrophotographic printer, a digital copying machine, and the like, a method of reading an image signal of a document once and then writing the image signal with a laser light source or an LED is mainly used.
To reproduce the gradation of the document density, a method of obtaining gradation by changing the dot density or changing the light potential by changing the amount of laser light to change the development contrast between the developing bias and the light potential There is known a method of obtaining the gradation by performing the above operation.

[0005]

[Problems to be solved by the invention]

In the former case, the dot reproducibility is low because the dot size is constant. In the latter case, the development contrast had to be increased in order to obtain gradation. However, in the case of a conventional photoreceptor, when the electric field was low, the slope of the light attenuation was reduced, and a sufficient development contrast was obtained. There was a disadvantage that it could not be obtained.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic apparatus capable of improving the above-mentioned disadvantages and obtaining a high-quality hard copy with good tone reproduction in a printer or a facsimile using a reversal development process. I do.

[0007]

[Means for Solving the Problems]

That is, the present invention relates to an electrophotographic apparatus having an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, and performs image exposure with laser light or LED light after charging. In the electrophotographic apparatus which obtains gradation by changing the light portion potential by changing the light amount of image exposure, the charge generation layer of the electrophotographic photosensitive member contains oxytitanium phthalocyanine, The dark area potential of the photoconductor is 700 in absolute value.
An electrophotographic apparatus, wherein the electrophotographic apparatus has a voltage of up to 1000 V and a process speed of 150 mm / sec or more.

Hereinafter, the present invention will be described in detail.

[0009] In the present invention (referred to hereinafter as V _d) dark potential of the photosensitive member in the latent image forming process of an electrophotographic apparatus in absolute value 70
0 to 1000V.

[0010] V _d is often set in the range of generally 600~700V as an absolute value. This hardly take a contrast potential and the One V _d is set equal to or less than 600V V _d and the light portion potential (hereinafter referred to as V _l), the margin of the potential variation due to repeated use and environmental fluctuation of the photosensitive member margin is because the no longer able to have, for the case of setting the V _d than the high potential 700V is the tilt of the optical attenuation in the low potential region is deteriorated,
The effect of increasing the _Vd setting was not obtained. This becomes more remarkable especially when the process speed is as high as 150 mm / sec or more, and the contrast potential cannot be obtained.

However, when oxytitanium phthalocyanine is used as the charge generation material, it has a sufficiently high sensitivity, so that sufficient photoresponse is obtained even when used at a high process speed of 150 mm / sec or more. Furthermore it tends tone reproduction can expand the contrast potential is obtained by setting the 700~1000V the V _d in absolute value. In addition, it has excellent electrophotographic characteristics in which potential fluctuation is extremely small even in repeated use and environmental fluctuation. Therefore, the effects of the present invention can be sufficiently obtained without any adverse effect.

Next, specific embodiments of the electrophotographic photosensitive member will be described. As the support having a conductive layer, a support having conductivity itself, for example, aluminum, an aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, or the like is used. In addition, plastics having a layer in which aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. are formed by a vacuum deposition method, supports or conductive materials impregnated with conductive particles in plastic or paper, For example, a plastic having a conductive polymer can be used.

An undercoat layer having a barrier function and an adhesive property can be provided between the conductive layer and the photosensitive layer. The undercoat layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, It can be formed of aluminum oxide or the like.

The thickness of the undercoat layer is 0.1 μm to 10 μm, preferably 0.1 μm to 10 μm.
μm to 3 μm is appropriate.

Further, it is preferable to provide a conductive layer between the support and the undercoat layer for the purpose of covering unevenness and defects of the support and preventing interference by scattering when image input is laser light. It is. This can be formed by dispersing conductive powder such as carbon black, metal particles, and metal oxide in a binder resin. The thickness of the conductive layer is preferably 5 to 40 μm, more preferably 10 to 30 μm.

Next, oxytitanium phthalocyanine used for the charge generation layer will be described. Oxytitanium phthalocyanine is a compound represented by the following general formula.

[0017]

Embedded image (In the formula, X ₁ , X ₂ , X ₃ , and X ₄ each independently represent Cl or Br, and n, m, l, and k each independently represent a number from 0 to _4. ) References relating to electrophotographic characteristics include, for example, JP-A-57-148745, JP-A-59-36254, JP-A-59-44054, and JP-A-59-44054.
31965, 61-239248 and 62-67094. The oxytitanium phthalocyanine obtained according to these is used as a charge generating material.

The charge generation layer can be formed by vapor deposition or by phenol resin, urea resin, melamine resin, epoxy resin, silicon resin, vinyl chloride-vinyl acetate copolymer, butyral resin, xylene resin, urethane resin , Acrylic resin, polycarbonate resin, polyacrylate resin,
Oxytitanium phthalocyanine is dispersed in a binder resin solution such as a saturated polyester resin or a phenoxy resin and applied. The film thickness is preferably 0.05 to 10μ
m, more preferably 0.1 to 3 μm.

As the charge transport material, general materials such as pyrazoline compounds, hydrazone compounds, stilbene compounds, triphenylamine compounds, benzidine compounds, and oxazole compounds can be used. These are dissolved in a solvent together with the same binder resin as used for the charge generation layer, and applied to form a charge transport layer. The ratio between the charge transport material and the binder resin is preferably set to 1: 3 to 3: 1, more preferably 1: 2 to 2: 1. Charge transport material is 1:
If it is less than 3, the charge transporting ability will be reduced, causing a decrease in sensitivity and an increase in residual potential. On the other hand, the charge transport material
If the ratio is more than 3: 1, the mechanical strength of the charge transport layer is reduced, and the photoreceptor cannot withstand repeated use.

Regarding the formation of each layer by these coatings, a dipping method,
Known coating methods such as a spray method, a beam method, a blade coat, and a spinner coat can be used.

Next, a latent image forming process in the electrophotographic apparatus will be described. The step of uniformly charging the photoreceptor is usually performed by corona discharge or a direct charging method in which a conductive member is brought into contact with the photoreceptor. In the present invention, the charging step is performed for the photosensitive member.
V _d is 700～1000V, is preferably set to be 850～1000V. Also, the portion in which written by the laser light source becomes V ₁ as an image signal corresponding to the density of an original.

FIG. 1 shows a schematic configuration example of a transfer type electrophotographic apparatus of the present invention.

In FIG. 1, reference numeral 1 denotes a drum-type photoconductor of the present invention as an image carrier, which is driven to rotate around an axis 1a in a direction of an arrow at a predetermined peripheral speed. The photosensitive member 1 is charged by charging means 2 during its rotation.
Then, the peripheral surface thereof is uniformly charged with a predetermined positive or negative potential, and then the exposure unit 3 receives a light image exposure L (such as laser beam scanning exposure) by an image exposure means (not shown). As a result, an electrostatic latent image corresponding to the exposure image is sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then developed with toner by a developing unit 4, and the developed toner image is transferred by a transfer unit 5 between a photosensitive unit 1 and a transfer unit 5 from a paper feeding unit (not shown). The transfer material P is sequentially transferred onto the surface of the transfer material P which has been synchronized and fed.

The transfer material P having undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means 8, subjected to image fixing, and printed out of the machine as a copy.

The surface of the photoreceptor 1 after the image transfer is cleaned by a cleaning unit 6 to remove the untransferred toner, and further subjected to a static elimination process by a pre-exposure unit 7 to be repeatedly used for image formation.

As the uniform charging means 2 for the photoconductor 1, a corona charging device is generally widely used. The transfer device 5 also generally uses a corona transfer unit. As an electrophotographic apparatus, a plurality of components such as the above-described photoreceptor, developing means, and cleaning means are integrally connected as an apparatus unit, and this unit is configured to be detachable from the apparatus body. May be. For example, the photoconductor 1 and the cleaning means 6 are integrated into one device unit,
It may be configured to be detachable using a guide means such as a rail of the apparatus body. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit.

When the electrophotographic apparatus is used as a copying machine or a printer, the light image exposure L is performed by reading a document and converting it into a signal, and scanning the laser beam and driving the LED array based on the signal.

When used as a facsimile printer,
The light image exposure L is an exposure for printing received data. FIG. 2 is a block diagram showing one example of this case.

The controller 11 controls the image reading unit 10 and the printer 19. The entire controller 11 is controlled by the CPU 17. The read data from the image reading unit 10 is transmitted to the transmission circuit 13.
Is transmitted to the partner station. Data received from the partner station is sent to the printer 19 through the receiving circuit 12. The image memory 16 stores predetermined image data. The printer controller 18 controls the printer 19. 14 is a telephone.

The image information received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12, then decoded by the CPU 17, and sequentially stored in the image memory 16. Is stored. When the image information of at least one page is stored in the memory 16, the image of the page is recorded. The CPU 17 reads out one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18. Printer controller
When receiving the image information of one page from the CPU 17, the 18 controls the printer 19 to record the image information of the page.

The CPU 17 receives the next page during recording by the printer 19. Image reception and recording are performed as described above.

The electrophotographic apparatus of the present invention can be widely used not only as an electrophotographic copying machine but also in electrophotographic application fields such as laser beam printers, LED printers, and laser plate making.

[0034]

【Example】

 Next, the present invention will be described with reference to examples.

Synthesis Example Synthesis of oxytitanium phthalocyanine: A mixture of 50 g of phthalodinitrile, 22.5 g of titanium tetrachloride, and 630 ml of α-chloronaphthalene was heated and stirred at 240 to 250 ° C. for 4 hours in a stream of N ₂ to perform a reaction. . Filter the product,
A mixture of the obtained dichlorotitanium phthalocyanine and 380 ml of concentrated aqueous ammonia was heated under reflux for 1 hour. The product was washed with acetone using a Soxhlet to obtain 22 g of oxytitanium phthalomcyanine.

Example 1 An Al cylinder of φ80 × 1360 mm was used as a support. A conductive layer composed of the following materials is applied on the support by a dipping method,
This was cured by heating at 140 ° C. for 30 minutes to form an 18 μm anti-scattering conductive layer.

Parts by weight Conductive pigment 10 parts Tin oxide coating treatment Titanium oxide (trade name: Kronos ECT-62, manufactured by Titanium Industries) Resistance adjusting pigment titanium oxide 10 parts (trade name: Tytone SR-1T, Sakai Chemical) Coating resin Phenol resin 10 parts (Product name: J-325, manufactured by Dainippon Ink) Surface roughness imparting agent Spherical silicon resin powder 1.5 parts (Product name: Tospearl 120, manufactured by Toshiba Silicon) Solvent 20 parts Methanol / methyl cellosolve = 1 / 1 Next, polyamide resin (trade name: Alamine CM-8000,
5% methanol solution of Toray Co., Ltd.
m was formed.

Next, 10 parts of oxytitanium phthalocyanine synthesized by the above-mentioned synthetic agent, 4 parts of polyvinyl butyral resin (trade name: Eslec BX-1, manufactured by Sekisui Chemical), and 200 parts of cyclohexanone using 1φ glass beads. Disperse in a sand mill for 10 hours and add tetrahydrofuran 300
~ 450 (appropriate) parts are added and applied by dipping on the undercoat layer,
A 0.15 μm charge generation layer was formed.

Next, as a charge transport layer, 10 parts of a stilbene compound having the following structural formula and 10 parts of a bisphenol Z-type polycarbonate resin (manufactured by Mitsubishi Gas Chemical), 45 parts of monochlorobenzene,
It was dissolved in 15 parts of dichloromethane to prepare a coating solution. This was applied on the charge generation layer by an immersion method to form a charge transport layer of 26 μm.

[0040]

Embedded image The photoreceptor thus prepared is mounted on a laser copying machine (CLC-1, manufactured by Canon) having a semiconductor laser light source.
Process speed 160mm / sec, V _d was set to charging conditions so that the -900 V. Further, the toner was developed with a one-component negative toner jumping method and the developing bias was set at -750V.

The results of evaluating the print image under such conditions are shown in the table.

Example 2 Coating up to the charge generation layer was performed in the same manner as in Example 1, and 9 parts of a compound having the following structure was formed as a charge transport layer.

[0043]

Embedded image A coating liquid was prepared by dissolving 10 parts of a styrene acrylic copolymer resin (trade name: MS-600, manufactured by Nippon Steel Corporation) in 40 parts of monochlorobenzene and 12 parts of dichloromethane. This was applied on the charge generation layer by a dipping method to form a 25 μm charge transport layer.

Image evaluation was performed using the same laser copying machine as in Example 1 at V _d = −850 V and a developing bias of −700 V. The results are shown in the table.

[0045] -600V a V _d set of Comparative Example 1 laser copier, the developing bias 45
Image evaluation was performed using the same photoconductor as in Example 1 except that the voltage was set to 0V. The results are shown in the table.

As a result, in the case of Examples 1 and 2, good gradation reproducibility of 10 levels was obtained for 10 levels of original density patterns.
On the other hand, sufficient contrast potential due to a set low as -600V to V _d In Comparative Example 1 can not be obtained, was only the reproducibility of 6 gradation.

The modified process speed of Example 3 laser copier such that the 320 mm / sec, -800 V and V _d setting, the developing bias -65
At 0 V, image evaluation was performed in the same manner as in Example 1 using the photoconductor of Example 1. The results are shown in the table.

Comparative Example 2 A photoconductor was coated in the same manner as in Example 1 up to the undercoat layer.

10 parts of the following compound as a charge generation layer,

[0050]

Embedded image Polyvinyl butyral resin (trade name: Eslec BL-
S, manufactured by Sekisui Chemical Co., Ltd.) and 200 parts of cyclohexanone were dispersed in a sand mill using 1φ glass beads for 50 hours, and 300 to 450 (as appropriate) parts of tetrahydrofuran were added thereto, and the mixture was applied to the undercoat layer. Was formed.

The charge transport layer was provided under the same conditions as in Example 1. Image evaluation was performed in the same manner as in Example 3 for setting the surface potential.

In the third embodiment, up to eight gradations out of ten steps can be reproduced, and the effect of the present invention is sufficiently recognized. On the other hand, in Comparative Example 2, V _l is increased to slow photoresponse of the photosensitive member is sufficient for the contrast potential is not obtained, the tone reproducibility has become worse.

[0053]

[Table 1]

[0054]

【The invention's effect】

As described above, in the electrophotographic apparatus of the present invention, in the reversal development process, even in a high-speed printer having a process speed of 150 mm / sec or more, high gradation reproducibility can be obtained and a high-quality image can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural view of a transfer type electrophotographic apparatus of the present invention. FIG. 2 is a block diagram of a facsimile using the electrophotographic apparatus as a printer.

[Explanation of symbols]

 1: Photoreceptor 2: Charging unit 3: Exposure unit 4: Developing unit 5: Transfer unit 6: Cleaning unit 7: Pre-exposure unit 8: Image fixing unit

Continuation of the front page (72) Inventor Hideyuki Ainoya 3-30-2 Shimomaruko, Ota-ku, Tokyo Referee Hiroshi Shirosho, Referee, Canon Inc. Referee Hiroshi Ueno Referee Tetsuo Taki (56) References JP Akira 64-65561 (JP, A) JP-A-2-230171 (JP, A) JP-A-59-146068 (JP, A) JP-A-63-26669 (JP, A) JP-A-2-264971 (JP, A A) JP-A-2-176768 (JP, A)

Claims (1)

(57) [Claims] 1. An electrophotographic apparatus comprising an electrophotographic photosensitive member having a charge generating layer and a charge transporting layer laminated in order on a conductive support, wherein after charging, a laser beam or
In an electrophotographic apparatus that performs image exposure with LED light and obtains gradation by changing the light part potential by changing the amount of image exposure, the charge generation layer of the electrophotographic photoreceptor includes oxytitanium phthalocyanine. Containing, the dark area potential of the electrophotographic photoreceptor is 700 to 1000 V in absolute value
And an electrophotographic apparatus having a process speed of 150 mm / sec or more.