Sharp Kabushiki Kaisha Corporation

Sayaka Fujita

Tatsuhiro Morita

Mikio Kakui

Masayuki Sakamoto

Yoshihide Shimoda

Tadashi Nakamura

Katsuru Matsumoto

Koichi Toriyama

Rikiya Matsuo

Satoshi Katayama

Hisayuki Utsumi

Kotaro Fukushima

Kazushige Morita

Tomoko Kanazawa

Toshihiko Murakami

Eiji Tenjiku

Yoichi Takesawa

Akiko Uchino

An image forming apparatus having excellent cleaning property for an electrophotographic photoreceptor and capable of forming a high-quality, high-resolution image. A surface free energy (&#x3b3;) of a photoreceptor (), which is provided in the image forming apparatus (), is set to 20 to 35 mN/m. A volume average diameter of toner particles included in a developer stored in a developing unit () to develop an electrostatic latent image and form a toner image is set to 4-7 &#x3bc;m When &#x3b3; of the photoreceptor () is set to within a small range as the particle size of toner is reduced, even small-particle-size toner having increased specific surface area and largely affected by a inter-molecular force is limited in adhesion to the surface of the photoreceptor () to provide a good cleaning property and a high-quality image can be formed.

Image forming apparatus equipped with an electrographic photoreceptor having a surface with low surface free energy

The master comprises a polyester resin as a binder resin and a carbon black as a colorant having a primary particle size of 10 nm to 100 nm, is blended with 30 to 60 parts by weight of the carbon black, has a lightness L* of 20 or more; and the reflectance A at 400 nm thereof and the reflectance B at 700 nm thereof fall within the range satisfying the relation given by the following formula [1]:0.5&#x3c;&#x3c;5[1] The carbon black in the toner can be made to be present stably in the conditions such that the carbon black has a small primary particle size and is homogeneously dispersed.

Master batch and toner for use in electrophotography

It is an object of the invention to inspect defects of a film formed on a relatively rough surface of a substrate by the light interference method. A substrate on which a film is formed is irradiated with light of a longer wavelength than the surface roughness Rmax or Rz of the substrate to obtain interference fringes to inspect defects of the film formed on the substrate. Especially, it is preferable that when the surface roughness Rmax or Rz is 0.5 &mgr;m or more, the substrate is irradiated with light of a wavelength beyond a little longer wavelength than the surface roughness Rmax or Rz. The surface of the substrate is subjected to a cutting process. Specifically, it is possible to inspect defects of the electric charge generation layer, electric charge transport layer, or undercoat layer of an electrophotographic photoreceptor. This photoreceptor is mounted in a digital copier or printer. Further, monochromatic light is preferably applied. Alternatively, indirect light of the light reflected from a reflector plate or the light diffused by a diffusing plate is preferably applied.

Film defect inspection method for a film formed on a substrate

The invention provides an electrophotographic photoreceptor, in which suppression of image defects and high sensitivity are compatible, and a method for production thereof. The invention also provides a coating fluid for forming a photosensitive layer and a method for production thereof, as well as an image-forming apparatus using said electrophoto-graphic photoreceptor. Briefly, the electrophoto-graphic photoreceptors may be constructed by forming an undercoating layer on a conductive support, and then forming a photosensitive layer on the undercoating layer. The undercoating layer contains titanium oxide particles in at least either needle shape or dendrite shape. The photosensitive layer contains an electric charge-generating material of which the primary particle size and cohesive particle size are in a range of 0.01 &mgr;m-10 &mgr;m. Accordingly, in the electrophotographic photoreceptors, it is possible to maintain high sensitivity and excellent durability and to form an image with no defect. The photosensitive layer in the electrophotographic photoreceptor has a multilayer structure consisting of a charge-generating layer and a charge-transporting layer. The charge-generating material is a phthalocyanine pigment.

Electrophotographic photoreceptor, process for production thereof, and image-forming apparatus using same

Test method and control method for coating liquid for electrophotographic photoconductor

An electrophotographic photosensitive element is provided with a photosensitive layer containing a charge generating substance and a charge transport substance on a conductive support. X-type metal-free phthalocyanine and a disazo compound are contained as a charge generating substance. With the photosensitive element, sufficient sensitivity is achieved so as to cause virtually no problem, and it is possible to reduce possibility of causing an instable electrostatic property such as a reduction in a charge potential and an increase in a remained potential, even in the case of frequent reuse.

Electrophotographic photosensitive element and manufacturing method thereof

Growing community of inventors

Kashihara, Japan

Sayaka Fujita