Abstract: An image-forming machine including a photosensitive drum which is rotatably disposed and successively passes through a charging zone, a developing zone and a transfer zone; a charger for charging the peripheral surface of the photosensitive drum into a predetermined polarity; a developing device for developing an electrostatic latent image formed on the peripheral surface of the photosensitive drum into a toner image; a transfer means for transferring the toner image formed on the peripheral surface of the photosensitive drum onto a transfer paper; and a foreign matter-recovering means which is disposed between the transfer zone and the charging zone and comes into contact with the peripheral surface of the photosensitive drum, and removes foreign matter adhered onto the peripheral surface of the photosensitive drum, the foreign matter-recovering means having a foreign matter-recovering brush brought into contact with the peripheral surface of the photosensitive drum, an elastic holding member made of an elas

Abstract: The present invention provides a novel naphthylenediamine derivative which is superior in electric charge transferring capability, compatibility with binding resin and stability. The above naphthylenediamine derivative is represented by the following general formula (1) ##STR1## wherein R.sup.1 to R.sup.4, R.sup.5a to R.sup.5f and a to d are as defined.

Abstract: An electrophotographic method in which an electrostatic latent image on a single-layer organic photosensitive material is developed while applying a developing bias voltage of the same polarity as the polarity of the charge of the photosensitive material. The developing bias voltage is set to be higher than a potential that corresponds to a point where a curve approximating the zone of a large amount of exposure to light and a curve approximating the zone of a small amount of exposure to light in a light decay characteristics curve intersect each other.

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: An electrophotosensitive material containing, as a charge-generating agent, a compound represented by the following general formula (1), ##STR1## wherein Cp is an azo coupling component, Y is a divalent organic group containing at least one aromatic ring or heterocyclic ring, R1 and R8 are alkyl groups or halogen atoms, respectively, and R2 and R4 are alkyl groups, halogen atoms or hydrogen atoms, respectively. The charge-generating agent used here remains chemically stable and exhibits excellent recurring property and charge-forming efficiency.

Abstract: An azo compound represented by the following general formula IA and an electrophotographic photosensitive member comprising a photosensitive layer containing the azo compound: ##STR1## wherein R.sup.1 and R.sup.2 are the same or different from each other and indicate a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, a carboxy group, an alkoxy carbonyl group, an acyl group, an aryl group, a halogen group or a cyano group, respectively; R.sup.14 indicates a hydrogen atom, a halogen group, an alkyl group, an alkoxy group, an aryl group, an amine group, a cyano group, a nitro group or a sulfoxide group; and A indicates a coupler residue having an acceptor property.

Abstract: An azo compound represented by the following general formula IA and an electrophotographic photosensitive member comprising a photosensitive layer containing the azo compound: ##STR1## wherein R.sup.1 and R.sup.2 are the same or different from each other and indicate a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, a carboxy group, an alkoxy carbonyl group, an acyl group, an aryl group, a halogen group or a cyano group, respectively; R.sup.14 indicates a hydrogen atom, a halogen group, an alkyl group, an alkoxy group, an aryl group, an amino group, a cyano group, a nitro group or a sulfoxide group; and A indicates a coupler residue having an acceptor property.

Abstract: An azo compound represented by the following general formula IA and an electrophotographic photosensitive member comprising a photosensitive layer containing the azo compound: ##STR1## wherein R.sup.1 and R.sup.2 are the same or different from each other and indicate a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, a carboxy group, an alkoxy carbonyl group, an acyl group, an aryl group, a halogen group or a cyano group, respectively; R.sup.14 indicates a hydrogen atom, a halogen group, an alkyl group, an alkoxy group, an aryl group, an amino group, a cyano group, a nitro group or a sulfoxide group; and A indicates a coupler residue having an acceptor property.

Abstract: The electrophotographic photoconductor of the present invention includes a conductive substrate and a photosensitive layer containing perylene pigment as a charge generating material formed on the conductive substrate. The X-ray diffraction peak of the perylene pigment exhibits its peak when the value of 2.theta. is 14.degree.(.+-.0.3.degree.), and the half-width of the peak when the value of 2.theta. is 14.degree. (.+-.0.3.degree.) is 0.5 or more. This electrophotographic photoconductor has excellent qualities of low residual potential and stabilized quality.

Abstract: Disclosed is a photosensitive material for the electrophotography, comprising as the charge-transporting substance a composition comprising an organic polysilane and a member selected from the group consisting of an electron-accepting substance, a diphenoquinone derivative, a low-molecular-weight hole-transporting substance, a high-molecular-weight polycyclic hindered phenol and an n-type charge-generating substance. Even if this photosensitive material is subjected to charging and light exposure repeatedly or irradiated with ultraviolet rays, quantities of charges of the surface voltage and residual voltage are very small, and the photosensitive material has an excellent resistance to the repetition of charging and light exposure operations and an excellent light resistance.

Abstract: A bis-azo compound represented by the following general formula and an electrophotographic photosensitive member having a light receiving layer containing said bis-azo compound. ##STR1## [wherein, two of the substituent groups R.sub.1 to R.sub.4 are respectively an azo group having a coupler residue which is bonded either directly or through a phenyl ring to the diphenoquinone skeleton, and the remaining two substituent groups are respectively hydrogen atom, alkyl group, alkenyl group, hydroxyl group, alkoxy group, carboxyl group, aryl group, halogen atom or cyano group wherein the two substituent groups may be identical or different each other, and Z is oxygen atom or sulfur atom.

Abstract: A stable .alpha.-type titanyl phthalocyanine composition including an .alpha.-type titanyl phthalocyanine and a metal-free phthalocyanine is disclosed having a wide range of absorption wavelengths and high in spectral sensitivity. The method for making the phthalocyanine composition is carried out by pigmenting a concentrated sulfuric acid solution containing at least titanyl phthalocyanine by an acid paste process. The concentrated sulfuric acid solution is poured into water to produce an .alpha.-type titanyl phthalocyanine composition which is stable to withstand the impact of aging. Also disclosed is an electrophotographic sensitive material which includes a sensitive layer having the .alpha.-type titanyl phthalocyanine composition superposed on an electroconductive substrate. This electrophotographic sensitive material excels in its charging property and its dark attenuation property and exhibits high sensitivity and low residual potential.

Abstract: The first aspect of this invention resides in providing an .alpha.-type titanyl phthalocyanine composition comprising an .alpha.-type titanyl phthalocyanine and metal-free phthalocyanine. This .alpha.-type titanyl phthalocyanine composition is stable, wide in range of absorption wavelengths, and high in spectral sensitivity because it contains an .alpha.-type titanyl phthalocyanine in combination with metal-free phthalocyanine.The second aspect of this invention resides in providing a method for the production of an .alpha.-type titanyl phthalocyanine composition comprising an .alpha.-type titanyl phthalocyanine and a metal-free phthalocyanine, which method comprises pigmenting a concentrated sulfuric acid solution containing at least titanyl phthalocyanine by the acid paste process consisting in pouring said concentrated sulfuric acid solution into water. By this method, an .alpha.-type titanyl phthalocyanine composition stable to withstand the impact of aging can be easily produced.

Abstract: There is disclosed an electrophotographic sensitive layer which is provided with a single-layer type sensitive layer containing a specific perylene type compound as an electric charge generating substance, a specific diamine derivative of the following general formula as an electric charge transferring substance, and a binding resin. ##STR1## wherein R.sup.5, R.sup.6, R.sup.7, and R.sup.