Sharp Kabushiki Kaisha Corporation

Makoto Uehara

Yasutaka Maeda

Katsuhiro Nagayama

Jitsuo Masuda

Takashi Kitagawa

Masayasu Narimatsu

Hiroshi Kawamoto

Toshihiro Ohta

Yasuyuki Ishiguro

Takahiko Kimura

Takeshi Wakabayashi

Toshio Nishino

Takanori Kamoto

Syouichi Fujita

Naotaka Funayama

Hirofumi Sakita

Daisaku Imaizumi

Masanori Kinomoto

Hiromi Nakatsu

Ken Yamagishi

Tomoe Matsuoka

Kaori Dakeshita

Yuka Sakagami

Kiyobumi Morimoto

Masakatsu Hayashi

Hiroji Kawamoto

Shouji Tomita

Tao Ou

An ink composition is prepared in such a manner that a difference between a dynamic surface tension (mN/m) measured by a maximum bubble pressure method at a temperature of 24 to 26&#xb0; C. and a static surface tension (mN/m) is within a range from 0 to 7 (mN/m). The ink composition is stored in an ink tank of an ink head, and is supplied from the ink tank to an ink chamber having a discharge port, and a voltage is applied to partitions formed by a piezoelectric material to apply a pressure by the partitions to the ink composition stored in the ink chamber, whereby a liquid droplet of the ink composition is discharged from the discharge port and the liquid droplet is deposited on a recording material to record an image.

Ink composition, recording method and recorded image utilizing the same, ink set and ink head

In case of a developing density correction based on a test image (patch image) density, normally, the developing density is carried out in a short period of time by correction (&#x3b3; correction) of a developing bias and a grid voltage (S). When a correction amount of the &#x3b3; correction exceeds an ordinary range, the &#x3b3; correction (S) and adjustment of toner concentration (magnetic permeability reference value) (S) are carried out in combination. Furthermore, when the toner concentration is changed, the setting of a correction reference of the &#x3b3; correction (&#x3b3; correction TBL) and correction timing of the &#x3b3; correction are accordingly changed (S, S). Therefore, in the developing density correction based on the test image density in the developing device using binary developer, it is possible to carry out the developing density correction, which is carried out in a short time, and whose correction width is wide, while maintaining the accuracy of a developing density adjustment.

Developing device, image forming device equipped therewith, and developing density adjusting method

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

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

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Nara, Japan

Makoto Uehara