Sharp Kabushiki Kaisha Corporation

Yasutaka Maeda

Katsuhiro Nagayama

Hideyuki Nishimura

Tsuyoshi Miyamoto

Taisuke Kamimura

Yukihiko Ueno

Yoichi Shimazawa

Masayuki Sakamoto

Makoto Kurokawa

Hideaki Taniguchi

Masaya Tsugoshi

Kazuyuki Ohnishi

Hiroshi Kawamoto

Makoto Uehara

Natsuko Tanaka

Hideo Matsuda

Osamu Fujimoto

Yuichi Kazaki

Toshihiro Ohta

Kyouichi Takata

Hiromi Washio

Takashi Kitagawa

Shunju Anzai

Masato Tokishige

Hidekazu Sakagami

Koichi Moriyama

Kazumi Irie

Takashi Kubo

Yasuyuki Ishiguro

Yoshie Iwakura

Takahiko Kimura

Takeshi Wakabayashi

Jitsuo Masuda

Syouichi Fujita

Toshio Nishino

Hidetoshi Kaneko

Yoshiaki Masuda

Naotaka Funayama

Daisaku Imaizumi

Hirofumi Sakita

Tokiyuki Okano

Masayasu Narimatsu

Kiyoshi Inamoto

Tomoe Matsuoka

Kazunori Sohda

Ken Yamagishi

Etsuzi Nukushina

Kaori Dakeshita

Mihoko Okada

Yuka Sakagami

Shouji Tomita

Tao Ou

Tsuyochi Miyamoto

Tuyoshi Miyamoto

Shin-ichirou Ohhashi

Hiroji Kawamoto

An image forming apparatus including a developing unit for stocking a developing agent containing toner and forming a toner image on a photosensitive medium with the developing agent, a toner supply unit for supplying the toner to the developing unit, a toner specific concentration detecting unit for detecting the toner specific concentration of the developing agent stocked in the developing unit, a humidity detecting unit for detecting humidity in the neighborhood of the developing unit, a storage unit for storing the humidity information detected by the humidity detecting unit, and a toner specific concentration correcting unit for controlling the toner supply amount of the toner supply unit on the basis of the humidity information stored to correct the toner specific concentration, wherein the toner specific concentration correcting unit compares newly-detected humidity with reference humidity corresponding to the humidity which is detected at the time when the developing agent is stocked into the developing unit or exchanged by new developing agent and which is stored in the storage unit, and corrects the toner specific concentration in accordance with the comparison result.

Image forming apparatus having humidity detection and toner concentration adjusting according to detected humidity

A photosensitive body for electrophotographical use has a conductive base body and a marking area provided thereon. The maximum surface roughness of a photosensitive layer provided right on the marking area is specified not to exceed 2.5 &mgr;m. And also, a ratio of the optical reflective index of the marking area to the optical reflective index of the non-marking area is specified to be in a range of 0.3 to 0.7. In this manner, even when the photosensitive layer is thin (not exceeding 25 &mgr;m), it is possible to prevent problems such as inadequate cleaning and toner falling. Hence, it is possible to offer a photosensitive body for electrophotographical use which can constantly produce high quality copied images.

Photosensitive body for electrophotographical use and manufacturing method thereof

Developing devices are provided adjacent to a light sensitive element. An intermediate transfer drum is provided adjacent to the light sensitive elements. After exposure of the light sensitive element, a first color or third color image is formed on the light sensitive element. On the other hand, after exposure of the light sensitive element, a second color or fourth color image can be formed on the light sensitive element. The first color image is transferred from the transfer unit to the intermediate transfer drum at the first transfer portion, and the second color image is transferred from the transfer unit at the second transfer portion so as to be superimposed on the first color image. Similarly, the third color image is transferred so as to be superimposed on the second image and the fourth color image is transferred so as to be superimposed on the third color image to the intermediate transfer drum. Accordingly, the first to fourth color images are superimposed. Thereby, downsizing of the device and cost reduction are achieved and image formation speed is facilitated.

Image formation apparatus and image formation method

An object of the present invention is to obtain, in an accurate and stable manner, an image density at a tone rise point in a low-density region in order to form a stable image. At the time of execution of an image density correction in an image forming apparatus which employs an electrophotographic process, a toner pattern of a plurality of toner patches is formed on the basis of a reference density correction table which specifies an image density output value used for correction of an image density input value, the density of the toner patches is detected by a density detecting sensor, points corresponding to a plurality of image densities in a low-density region, detected above a predetermined level of sensitivity of the sensor, are plotted thereby to find a linear interpolation formula, an image density in the low-density region below the predetermined level of sensitivity of the density detecting sensor is interpolated with the linear interpolation formula, a comparison between the reference density correction table and a result of the interpolation is made so as to correct the image density output value, and a correction table as a post-modification correction table is prepared. An actual image is prepared using the correction table.

Image forming apparatus

A high density detecting toner pattern is formed on a photosensitive body and a high density correction is effected by comparing a value detected by a reflection sensor with a high density reference value so as to maintain an image density at a specific level. An image density correcting section adopts a result of the preceding high density correction as the high density reference value, and compares the same with a result of a current high density correction. The image density correcting section effects the half-tone density correction only when a difference reaches or exceeds a preset difference reference value by forming a half-tone density detecting toner pattern on the photosensitive body and comparing a value detected by the reflection sensor with a half-tone reference value. Consequently, it has become possible to provide an image forming apparatus which can maintain a density output of an entire image at a specific level for any kind of images including solid, line, and half-tone, etc. while shortening a time required for the density correction and reducing a quantity of toner consumed for the density correction.

Image forming apparatus with half-tone density control

A developing device having a reduced size in the horizontal direction and in which a developing agent is transported with stirring along a circulating route inside a developing tank to effectively mix newly added toner therewith and stir the mixture. A developing tank for storing developing agent therein is horizontally divided with a partition member thereby providing an upper chamber and a lower chamber. A developer roller and a stirring roller are disposed in the lower chamber. Two screw rollers are disposed in the upper chamber. An inlet opening is formed between an end of the partition member and a regulating member for restricting a layer if the developing agent adsorbed to the developing roller. A developing agent removed by the restricting member is fed through an inlet opening to the screw rollers in the upper chamber. The developing agent is mixed with fresh toner supplied through a supply inlet and transported with being stirred by the screw roller in its axial direction. Then, the developing agent is transferred to the screw roller disposed parallel to the screw roller and it is further transported and returned to the stirring roller in the lower chamber through a return port provided opposite to the screw roller. The compact construction of the developing device is realized by arranging screw rollers for stirring and transporting toner in the upper chamber.

Developing device having a reduced width in the horizontal direction

A photosensitive body for electrophotographical use has a conductive base body and a marking area provided thereon. The maximum surface roughness of a photosensitive layer provided right on the marking area is specified not to exceed 2.5 .mu.m. And also, a ratio of the optical reflective index of the marking area to the optical reflective index of the non-marking area is specified to be in a range of 0.3 to 0.7. In this manner, even when the photosensitive layer is thin (not exceeding 25 .mu.m), it is possible to prevent problems such as inadequate cleaning and toner falling. Hence, it is possible to offer a photosensitive body for electrophotographical use which can constantly produce high quality copied images.

Photosensitive body for electrophotographical use and manufacturing

A test patch image is formed and the density thereof is detected to maintain the image quality at a constant level. One of the image forming conditions, for example, the developing bias voltage of the developing unit inside the image forming apparatus that serves as a density controller, and is controlled in accordance with the detection result. Here, a humidity sensor for detecting the environmental change, that is, the humidity, is provided inside the apparatus, and the reference value of the toner mixing ratio is changed and corrected while the developing unit is operating when the humidity sensor detects a change in humidity. However, the toner mixing ratio is maintained and neither changed nor corrected when the density of the test patch image remains at the same level, so that the developing bias voltage is not corrected. Consequently, the correction of the toner mixing ratio is neither changed nor corrected in response to the change in humidity alone, thereby making it possible to maintain a stable image quality state.

Image forming apparatus including image quality compensation means

An image forming apparatus is designed to compensate for voltage to be applied to an exposure lamp and a charger in accordance with changes in the density of a toner image formed on a photoreceptor that occur from its initial state to its final state after an image forming operation. More specifically, the density of a reference toner image is measured by a toner-density sensor. The amount of change in the density is measured beginning with its initial state by a subtracter, and the amount of compensation for the voltage required for obtaining the optimum image quality is found. By using these amounts of compensation as teaching data, learning is made as to the relationship between the amount of change in the density and the amount of compensation in a neurocomputer. Upon forming an image, the neurocomputer executes operations in accordance with the contents of the learning based on an inputted amount of change in density, and finds an appropriate amount of compensation. With this arrangement, it is possible to constantly obtain copied images having stable image quality, and to lower the cost of image forming apparatuses by reducing the number of parts used for the sensors or other devices.

Image forming apparatus having an image-quality correction function

A color balance adjusting apparatus is used for a full color copier in which an original image is illuminated by a light source; the illuminated image is exposed onto a photoreceptor to form electrostatic latent images corresponding to first, second and third colors for creating a color image; and each of the formed electrostatic latent images is developed into a visualized toner image. The color balance adjusting apparatus includes an infrared sensor for detecting toner density of the toner image formed with a toner having any one color of the first, second and third colors. The apparatus further includes automatic adjustment means which determines a relation of light intensity to toner density detected for one color by varying light intensity of said light source, and which determines optimal light intensity for the other two colors as predetermined functions of obtained optimal light intensity. Using this apparatus, automatic adjustment of the color balance for each copy mode can be effected in a short time with lesser consumption of electricity and supplies.

Color balance adjusting apparatus for full-color copier

The present invention provides a compact electrophotographic device in which the gap between a screen and a photosensitive body can be kept uniform throughout the screen, no fogging is caused on a copied imaged, no wasteful space is around the photosensitive body, color contaminations are completely prevented and the quality of a color copied image is improved.

Electrophotographic apparatus with reduced contamination from toner

Growing community of inventors

Ikoma, Japan

Yasutaka Maeda