Seiko Epson Corporation

Takashi Hama

Hiroshi Nakazato

Hidetsugu Shimura

Yujiro Nomura

Nozomu Inoue

Kyu Takada

Keiichi Taguchi

Hidenori Kin

Yoshio Nakazawa

Yoshihiro Nakashima

Ken Ikuma

Yoichi Yamada

Takatomo Fukumoto

Takehiko Okamura

Takayuki Kawakami

Kenjiro Yoshioka

Hajime Kurihara

Akihiko Ikegami

An image It is formed as a patch image which includes a header image portion Ih of a solid image having a length of a circumferential length of a developing roller or more, and a gradation image portion Ig progressively varied in the tone level thereof from the maximum level to the minimum level. The densities of the patch image on an intermediate transfer belt are sampled. However, the sampling results contain errors resulting from noises or variations and hence, are subjected to a noise removal process, a periodical variation correction process and a reverse correction process. The results detected on the intermediate transfer belt do not always coincide with image densities (OD values) on a recording material. Therefore, the detection results are converted into the OD values, based on which tone characteristics of an apparatus is estimated. Then a tone correction table is updated in a manner to compensate for the tone characteristics. This approach is taken to improve image quality on the recording material.

Image forming apparatus and method for controlling tone characteristics based on tone-control patch image

A test pattern Plonger than a length Ld corresponding to a circumferential length of a developing roller is formed along a moving direction of a photosensitive member (or developing roller). The developing roller transports a great quantity of toner on its surface in a first revolution thereof and hence, the test pattern has a high density. When the residual toner runs low, the toner transport quantity is decreased in the subsequent revolution, so that the test pattern Pis decreased in the density at its portion beyond the length Ld from its head. If a density difference is observed at place corresponding to a boundary between image portions formed in the first revolution and the second revolution, it is concluded that image quality is degraded due to the shortage of residual toner.

Apparatus for forming image-quality evaluation image

When the remaining toner amount within a developer is relatively large, a control target value of a toner amount is set to Ttgtand a lower limit value of a toner amount which can regarded proper is set to TL. When the density of a patch image formed under a predetermined condition is smaller than a minimum guaranteed density Dma, it is determined abnormality has occurred in the apparatus. Since the characteristic of toner within the developer changes as the remaining toner amount decreases, the control target value is changed to Ttgtand the lower limit value is set to TLin light of this. In this fashion, regardless of whether the toner characteristic has changed, abnormality in the apparatus is detected without fail.

Image forming apparatus, control method and toner consumption calculating apparatus and method

In a density control technique wherein a density of a toner image formed as a patch image is detected for performing density control based on the detected result, detection errors are decreased so as to properly set a density control factor. The density control factor is optimized based on a variation rate of the patch image densities against a varied density control factor. The detected results of the patch image densities are corrected based on information on an image carrier acquired before the formation of the patch images.

Image forming apparatus and image forming method for performing density control of toner images

Optimization of a density control factor accompanying formation of a patch image is executed every time a predetermined period of time elapses since the end of a preceding image forming operation. Since an image is formed at regular intervals in this manner, it is possible to suppress a density variation which is created as toner carried on a developer roller is left unused for long. This effect further improves when the developer roller is rotated idle prior to formation of a patch image or regularly at predetermined timing.

Image forming apparatus and image forming method

Image forming apparatus and image method for forming toner images with optimized patch image density

Image forming apparatus and image forming method involving application of a developing bias to a toner carrier

A gradation patch image Ip used for determination of tone characteristics of an apparatus is progressively varied in the tone level thereof from the maximum tone level (level) to the minimum tone level (level). The gradation patch image is either a toner image continuously and consistently varied in the tone level thereof or a toner image having the tone levels varied stepwise at a smaller pitch than a width of a detection region of a patch sensor. In density detection of such a gradation patch image Ip, toner image densities at portions on either sides in the detection region of the patch sensor are canceled each other out by averaging and hence, only a toner image density substantially at the center of the detection region can be obtained.

Output signals Vp from a density sensor are sampled for plural positions on an intermediate transfer belt and an amount of toner adhesion is determined based on the results of sampling. Since these sample data pieces may contain noises, each predetermined number of data pieces of higher order and of lower order are removed from the resultant sample data string. The removed data pieces are each replaced by an average value Vpavg of the other sample data pieces. The amount of toner adhesion is calculated based on the data string thus replaced.

Image forming apparatus, toner-adhesion calculation method and data processing method

A condition controlling process is executed when parameters expressing a state of toner within a developer reaches predetermined threshold values. On each one of two parameters, namely, a dot count value which is indicative of a toner consumption amount (an integrated value of the number of dots formed using an exposure beam) and a developer roller rotating time which is indicative of the degree of toner fatigue, a threshold value (denoted at the dotted lines) which triggers execution of the condition controlling process is set. At the time that the path d of dots which are expressed as combinations of these parameters intersects each dotted line (the intersections (1) through (6)), the condition controlling process is executed.

Apparatus for and method of forming image under controlled image forming condition

A light emitting element irradiates light upon a surface area of an intermediate transfer belt which is wound around a roller, i.e., upon a wind area, and light receiving units receive light reflected at the wind area. Based on a signal outputted from a sensor, the quantity of toner is measured. In the wind area, the intermediate transfer belt does not flap in a direction which is approximately perpendicular to a direction in which the belt travels. This suppresses a change in distance (sensing distance) between the sensor and the intermediate transfer belt.

Method of and apparatus for measuring quantity of toner on belt-shaped image carrier

A development bias calculation and an electrifying bias calculation are executed in this order. In the development bias calculation, a plurality of toner images are formed as first patch images while changing the development bias. An optimal development bias, which is necessary to obtain the target density, is determined based on densities of the first patch images. In the electrifying bias calculation, toner images are formed as second patch images while changing the electrifying bias with the development bias fixed to the optimal development bias. An optimal electrifying bias, which is necessary to obtain the target density, is determined based on densities of the second patch images.

Image forming apparatus with predetermined target density and method

A toner quantity measuring apparatus in which an input offset voltage is applied to the output side of an irradiation quantity monitoring light receiving element, so that a light emitting element remains turned off unless a light quantity control signal exceeds a predetermined signal level. Prior to irradiation of light upon an intermediate transfer belt and measurement of a toner quantity, a light quantity control signal below the predetermined signal level is supplied to an irradiation quantity adjusting unit and the light emitting element is turned off without fail. A memory stores, as a dark output voltage, an output voltage from a reflection quantity detecting unit upon the turning off. Light reflected from the intermediate transfer belt is split into p-polarized and s-polarized light to detect a toner quantity and colors of the toner. In actual measurement of the toner quantity, with light irradiated upon the intermediate transfer belt, the dark output voltage is subtracted from the output voltage outputted from the reflection quantity detecting unit, whereby an influence of the dark output voltage is eliminated.

Apparatus for measuring quantity of toner, and image forming apparatus comprising measuring apparatus

An improved optical scanning apparatus is adapted to be such that at either end of the scan range, an optical beam deflected by a reflecting surface of a scanner will pass through an anamorphic lens in scanning optics at a position spaced from its optical axis in the sub-scanning direction. The anamorphic lens has such a sectional profile in the sub-scanning direction that the lens thickness at one end of the sub-scanning direction differs from the thickness at the other end. Also, a high speed optical scanning apparatus based on the dual incidence and the oblique incidence, can prevent a positional variation of a scanning line that is due to a shift of each facet of the rotating polygonal mirror, which is caused by an offset of the rotating axis of the rotating polygonal mirror. The scanning apparatus includes a light source, a rotating polygonal mirror with a plural number of reflecting surfaces for reflecting and deflecting an optical beam emitted from the light source, transfer optics for receiving the optical beam that is reflected and deflected by a first reflecting surface of the rotating polygonal mirror and transferring the optical beam to a second reflecting surface of the mirror, and scanning optics for scanning a scanned surface with the optical beam that is reflected and deflected by the second reflecting surface.

Optical scanning apparatus

In an apparatus, first and second processing modes are prepared to determine an optimal development bias. Either one of the first processing mode and the second processing mode is selected as a processing mode in accordance with an operation status of the apparatus. Hence, it is possible to select and execute the most appropriate processing mode in accordance with an operation status to thereby efficiently and highly accurately determine an optimal value of a development bias which is one density controlling factor.

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Nagano-ken, Japan

Takashi Hama