Abstract: This invention provides an image forming apparatus capable of effectively suppressing an AC color registration error, and a control method thereof. To accomplish this, the image forming apparatus according to this invention controls driving of a transfer belt so that the speed of surface of the transfer belt at the transfer position comes close to a constant speed. The image forming apparatus also controls driving of a photosensitive drum so that the error between the speed of surface of the photosensitive drum and that of the transfer belt at the transfer position becomes almost 0. Further, the image forming apparatus controls the exposure timing in accordance with fluctuations of the speed of surface at the exposure position so that the exposure interval in the sub-scanning direction on the photosensitive drum comes close to a constant interval.

Abstract: For suppressing density unevenness which is caused by changes in a main scanning line interval of a laser beam on the image bearing member due to a polygonal face tangle, laser luminance is controlled so as to maintain the density unevenness with a spatial frequency sensitive to human visibility substantially constant.

Abstract: This invention provides an image forming apparatus capable of effectively suppressing an AC color registration error, and a control method thereof. To accomplish this, the image forming apparatus according to this invention controls driving of a transfer belt so that the speed of surface of the transfer belt at the transfer position comes close to a constant speed. The image forming apparatus also controls driving of a photosensitive drum so that the error between the speed of surface of the photosensitive drum and that of the transfer belt at the transfer position becomes almost 0. Further, the image forming apparatus controls the exposure timing in accordance with fluctuations of the speed of surface at the exposure position so that the exposure interval in the sub-scanning direction on the photosensitive drum comes close to a constant interval.

Abstract: A sampling unit samples plural input signals, and detects a point (change point) at which one of the sampled input signals shows a change in the logic level. In case the logic level after the detection of the change point continues for a predetermined time, the plural sampled data are respectively latched or outputted after the lapse of the predetermined time, and, in any other timing, the sampled data are held, thereby obtaining plural noise-eliminated signals. One of the plural input signals is a clock signal, and, in case of data transmission in synchronization with such clock signal, the transmission is executed with a timing synchronized with the noise-eliminated signal. The predetermined time is selected equal to or less than ¼ of the cycle period of the communication synchronization clock signal.

Abstract: For suppressing color density unevenness due to a polygonal face tangle, laser luminance is controlled so as to maintain the color density unevenness with a spatial frequency sensitive to human visibility substantially constant.

Abstract: A sampling unit samples plural input signals, and detects a point (change point) at which one of the sampled input signals shows a change in the logic level. In case the logic level after the detection of the change point continues for a predetermined time, the plural sampled data are respectively latched or outputted after the lapse of the predetermined time, and, in any other timing, the sampled data are held, thereby obtaining plural noise-eliminated signals. One of the plural input signals is a clock signal, and, in case of data transmission in synchronization with such clock signal, the transmission is executed with a timing synchronized with the noise-eliminated signal. The predetermined time is selected equal to or less than ¼ of the cycle period of the communication synchronization clock signal.

Abstract: A sampling unit samples plural input signals, and detects a point (change point) at which one of the sampled input signals shows a change in the logic level. In case the logic level after the detection of the change point continues for a predetermined time, the plural sampled data are respectively latched or outputted after the lapse of the predetermined time, and, in any other timing, the sampled data are held, thereby obtaining plural noise-eliminated signals. One of the plural input signals is a clock signal, and, in case of data transmission in synchronization with such clock signal, the transmission is executed with a timing synchronized with the noise-eliminated signal. The predetermined time is selected equal to or less than ¼ of the cycle period of the communication synchronization clock signal.

Abstract: A sampling unit samples plural input signals, and detects a point (change point) at which one of the sampled input signals shows a change in the logic level. In case the logic level after the detection of the change point continues for a predetermined time, the plural sampled data are respectively latched or outputted after the lapse of the predetermined time, and, in any other timing, the sampled data are held, thereby obtaining plural noise-eliminated signals. One of the plural input signals is a clock signal, and, in case of data transmission in synchronization with such clock signal, the transmission is executed with a timing synchronized with the noise-eliminated signal. The predetermined time is selected equal to or less than ¼ of the cycle period of the communication synchronization clock signal.

Abstract: An image encoding apparatus of this invention extracts a character/line image from a multi-value image, and substitutes image information corresponding to the extracted character/line image with substitution data based on the image information. Thereafter, the apparatus encodes the image information corresponding to the character/line image, and the remaining image information by different methods, thereby performing efficient image encoding while preserving quality of a character/line image in a multi-value image.

Abstract: A stepping-motor driving system includes a driver for driving a stepping motor by switching an exciting phase thereof. The driver includes a delay-compensation-type pulse-width modulation circuit for compensating for the delay caused by the time constant of an exciting coil of the stepping motor. The delay-compensation-type pulse-width modulation circuit compensates for the delay in the rise and/or fall of the current of the exciting coil. The system also includes a memory for storing time data of the differential value of an immediately preceding exciting-phase switching time in a table of an exciting-phase switching time of the stepping motor. The system also includes a controller for controlling the driver. The controller includes a timer. The controller increments the timer until the count of the timer equals the value of one of the time data stored in the memory.

Abstract: A color image forming apparatus forms a color image by superposing images of plural colors in plane-sequential manner. In the color image forming apparatus, the amount of aberration between the detection signal for the recording medium for the first color and the horizontal synchronization signal is measured by a counter, and the start timing of image formation of the second and subsequent colors is controlled by a delay device, according to the measured amount of aberration.

Abstract: An apparatus for effecting recording and/or reproduction of information by scanning an optical recording medium with a condensed light beam includes a detecting device for detecting a focusing error signal of the light beam, a focusing servo device for correcting a focusing state of the light beam on the basis of the focusing error signal, and a device for detecting abnormality of the focusing servo.

Abstract: In an apparatus using an optical recording medium having a plurality of parallel tracks and a region which indicates tracking control provided in part of the longitudinal direction of each track, information is recorded and/or reproduced by scanning the tracks with a light beam, and a track jumping device transfers the light beam from the presently scanned track to another track when the light beam is not scanning such region.

Abstract: An apparatus for recording and/or reproducing information by scanning a light beam on a track of an optical recording medium, while the track is tracking-controlled and/or focusing-controlled is disclosed. The track being scanned has a preformat signal partially recorded in a longitudinal area thereof, and the tracking control and/or focusing control are stopped while the light beam passes through the area of the track in which the preformat signal is recorded.

Abstract: There is disclosed an optical information processing apparatus comprising a scan device for effecting the recording and/or reproduction of information by scanning an optical record medium with a light beam spot, a detector for detecting the relative speed between the medium and the beam spot, and a controller for bringing the beam spot to a defocus state on the medium when the relative speed is detected to be a below a predetermined value.