Abstract: An image forming apparatus which can exhibit an excellent charge eliminating effect by erasing a transfer memory using a precharging device with optimized conditions even when a positively-charged single-layer-type electrophotographic photoconductor is used as a photoconductor. In the image forming apparatus which sequentially arranges a charging device, a developing device, a transfer device, and a charge eliminating device around a single-layer-type electrophotographic photoconductor, the charging device charges a surface of the single-layer-type electrophotographic photoconductor with a positive polarity, a precharging device having a conductive member is arranged on an upstream side of the charge eliminating device, the conductive member is brought into contact with the electrophotographic photoconductor, and a current density Ib (?A/m2) of the injected current into the photoconductor from the conductive member is set to a value of 700 (?A/m2) or more.

Abstract: The present invention provides an image forming apparatus which can exhibit an excellent charge eliminating effect by erasing a transfer memory using a precharging means with optimized conditions even when a positively-charged single-layer-type electrophotographic photoconductor is used as a photoconductor. In the image forming apparatus which sequentially arranges a charging means, a developing means, a transfer means, and a charge eliminating means around a single-layer-type electrophotographic photoconductor, the charging means charges a surface of the single-layer-type electrophotographic photoconductor with a positive polarity, a precharging means having a conductive member is arranged on an upstream side of the charge eliminating means, the conductive member is brought into contact with the electrophotographic photoconductor, and a current density Ib(?A/m2) of the injected current into the photoconductor from the conductive member is set to a value of 700(?A/m2) or more.

Abstract: The present invention provides an electrophotographic photoreceptor comprising a photosensitive layer that contains at least a charge generating agent, a hole transport agent and a predetermined additive. The hole transport agent satisfies the following formulas (A) and (B). The electrophotographic photoreceptor prevents image defect from occurring and can meet the demand for higher speed image forming apparatuses, by reducing the adhesion of paper dust and preventing the occurrence of cracks. ? ? ? M < 1.2 × 10 - 8 ( A ) ? ? ? > 5.

Abstract: The present invention relates to a novel titanyl phthalocyanine crystal which can prepare a coating solution having excellent storage stability because it satisfies both of the following two characteristics (a) and (b), a method of producing the same, an electrophotosensitive material using the above crystal as an electric charge generating material. (a) The crystal has a maximum peak at a Bragg angle 2?±0.2°=27.2° and has no peak at 7.4° in a CuK? characteristic X-ray diffraction spectrum. (b) The crystal does not have a peak of a change in temperature within a range from 50 to 400° C. except for a peak associated with evaporation of adsorbed water in differential scanning calorimetry.

Abstract: An electrophotographic photoreceptor is disclosed which includes a conductive resin substrate and a resin layer. The resin layer includes a binding resin and is formed on the conductive resin substrate. The difference between the solubility parameter of the conductive resin substrate and the solubility parameter of the resin layer of the photoreceptor is 2.5 (J/cm3)1/2 or less.

Abstract: An electrophotographic photoreceptor is disclosed which includes a conductive resin substrate and a resin layer. The resin layer includes a binding resin and is formed on the conductive resin substrate. The difference between the solubility parameter of the conductive resin substrate and the solubility parameter of the resin layer of the photoreceptor is 2.5 (J/cm3)1/2 or less.

Abstract: The present invention relates to a novel titanyl phthalocyanine crystal which can prepare a coating solution having excellent storage stability because it satisfies both of the following two characteristics (a) and (b), a method of producing the same, an electrophotosensitive material using the above crystal as an electric charge generating material.

Abstract: Disclosed is a single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer made of a binder resin containing at least an electric charge generating material and an electric charge transferring material, which is formed on the conductive substrate, wherein an oxygen transmission rate of the binder resin is not more than 35 cc·mm/m2·day·atom, wherein it is preferred that a mobility at an electric field strength of 5×105 V/cm of the hole transferring material is not less than 5×10−6 cm2/V/sec and a solid content of the electric charge transferring material is not less than 30% by weight and not more than 50% by weight based on the whole solid content; said electrophotosensitive material has good ozone resistance and does not cause defects such as image black belt due to lowering of the charge capability, an ozone of which is 5.0 ppm at most, and is also superior in sensitivity and wear resistance.

Abstract: The invention relates to an electrophotosensitive material comprising an organic photosensitive layer and an inorganic surface protective layer, wherein at least an outermost part of the organic photosensitive layer contains a diphenylamine compound represented by a formula (1): wherein ‘A’ denotes a groups combined with two phenyl groups in the formula in a manner to jointly form a &pgr;-electron conjugated system. The electrophotosensitive material features more excellent durability because the compound functions as a binder for combining the organic photosensitive layer with the inorganic surface protective layer so that the surface protective layer is less prone to suffer cracks or delamination.

Abstract: Disclosed is a single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer made of a binder resin containing at least an electric charge generating material and an electric charge transferring material, which is formed on the conductive substrate, wherein an oxygen transmission rate of the binder resin is not more than 35 cc·mm/m2·day·atom, wherein it is preferred that a mobility at an electric field strength of 5×105 V/cm of the hole transferring material is not less than 5×10−6 cm2/V/sec and a solid content of the electric charge transferring material is not less than 30% by weight and not more than 50% by weight based on the whole solid content; said electrophotosensitive material has good ozone resistance and does not cause defects such as image black belt due to lowering of the charge capability, an ozone of which is 5.0 ppm at most, and is also superior in sensitivity and wear resistance.

Abstract: The invention relates to an electrophotosensitive material comprising an organic photosensitive layer and an inorganic surface protective layer, wherein at least an outermost part of the organic photosensitive layer contains any one of the compounds represented by formulas (1) to (4).

Abstract: The invention relates to an electrophotosensitive material comprising an organic photosensitive layer and an inorganic surface protective layer, wherein at least an outermost part of the organic photosensitive layer contains a diphenylamine compound represented by a formula (1): 1

Abstract: A single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer made of a binder resin containing at least an electric charge generating material and a hole transferring material and an electron transferring material as an electric charge transferring material, which is formed on the conductive substrate, characterized in that the binder resin contains a polycarbonate resin having a repeating structural unit represented by the general formula [1] and the solid content of the hole transferring material and the electron transferring material is not less than 30% by weight and not more than 50% by weight relative to the entire solid content, exhibits good wear resistance with respect to the photosensitive layer and is also superior in durability.

Abstract: The present invention relates to a positive charging single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, said photosensitive layer comprising an electron charge generating material, a hole transferring material, an electron transferring material and a binder resin, wherein a mobility of the hole transferring material at an electric field strength of 5.times.10.sup.5 V/cm is not less than 1.times.10.sup.-5 cm.sup.2 /V/sec and the electron transferring material has a mobility of not less than 1/20000 and not more than 1/10 relative to that of the hole transferring material. Said positive charging single-layer type photosensitive material has a sufficient sensitivity even when used in a high-speed image forming apparatus capable of taking 50 or more copies of a A4-size original.

Abstract: The present invention provides a naphthoquinone derivative represented by the general formula (I): ##STR1## wherein R.sup.1 and R.sup.2 are as defined in the specification. An electrophotosensitive material containing this naphthoquinone derivative as an electron transferring material has high sensitivity.

Abstract: The photosensitive material of the present invention is provided in contact with a developing roller and has a surface potential decay characteristic in which when the photosensitive material is charged to a surface potential of 800 V and is contacted with the developing roller to which a voltage (VR) is applied, the surface potential (VD) of the photosensitive material after contacting is represented by the formula (1):VD.gtoreq.800.times.EXP (0.00235.times.VR).By using this photosensitive material, a transverse black stripe in the tip of the transfer paper is prevented and it is possible to form an image having excellent image quality and image density.

Abstract: The present invention provides a naphthoquinone derivative represented by the general formula (I): ##STR1## wherein R.sup.1 and R.sup.2 are as defined in the specification. An electrophotosensitive material containing this naphthoquinone derivative as an electron transferring material has high sensitivity.

Abstract: An electrophotosensitive material of the present invention is formed by providing a photosensitive layer containing a bis-azo pigment expressed in formula (1): ##STR1## wherein A.sup.1, A.sup.2, R.sup.1 and n are as defined, as a charge generating material, and a diamine compound expressed in formula (2): ##STR2## wherein R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 p and q k, l, m and o are as defined, as a charge-trasferring material, on a conductive substrate. As a charge generating material, a perylene pigment, anthanthrone pigment, X-type metal-free phthalocyanine pigment, imidazoleperylene pigment or perylene bis-azo pigment are preferable used together with the bis-azo pigment. Thus, photosensitive material is excellent in sensitivity and durability.

Abstract: In accordance with the present invention, there is provided a phenanthrylenediamine derivative represented by the general formula (1). The derivative is excellent in the electric charge transferring capability, the compatibility with a binding resin and the stability, thereby providing a photosensitive material which is highly sensitive and excellent in the durability. ##STR1## ?wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each represent a halogen atom, an alkyl group, an alkoxy group or an aryl group; and a, b, c and d each represent an integer from 0 to 5!.

Abstract: The present invention provides a novel naphthylenediamine derivative which is superior in electric charge transferring capability, compatibility with binding resin and stability, and an electrophotosensitive material which has a higher sensitivity and an excellent durability. The above naphthylenediamine derivative is represented by the following general formula (1), and the electrophotosensitive material is formed by providing a photosensitive layer having this naphthylenediamine derivative as an electric charge transferring material on a conductive substrate. ##STR1## wherein R.sup.1 to R.sup.4, R.sup.5a to R.sup.5f and a to d are as defined.