Abstract: In a halftoning unit of a laser printer and the like, a high speed, high density and high gradations halftoning is realized by multi-value implementation by clustered dot concentrated dither halftoning (known as a sub-matrix method) and PWM distributing gradation among the plurality of halftone dots with a small memory and circuit. For this purpose, the value of the difference between an input gradation value ni and a threshold value nc, &Dgr;n=ni−nc, is shortened within a range of 0 to &Dgr;h and the lower s bit of &Dgr;h is removed by a round-down or round-up process. Meanwhile, a threshold array is generated from an extended threshold pattern obtained by combining threshold patterns of 2s whose threshold interval is &Dgr;h, i.e. &Dgr;Ah×K, &Dgr;h×K+1, . . . , &Dgr;×K+2(s−1). Thereby, a halftone dot dither process in which the PWM gradation increases distributively among the 2s dots may be realized with a small scale memory and circuit.

Abstract: In the picture quality stabilizer for a color laser printer, changes in the gray level characteristic and the color balance caused by changes in temperature and humidity are compensated in order to stabilize the reproduced image. The apparatus includes a temperature and humidity sensor, an upper-bound correction table, a gamma correction table and a mixed color correction table, each optimized with respect to a reference environment, interpolation means for those tables, and a gray level correction means for correcting the gray level with correction coefficients obtained by the interpolation means and the mixed color correction means for compensating any failure of the color balance with the linear transformation. With this configuration, the correction coefficients are so modified as to establish a stable gray level characteristic and color balance, and a stable reproduced image can be obtained.

Abstract: A raster device such as a digital printer or the like which sequentially compares input image data with each element in a threshold matrix to convert the input image data into binary or multi-level pixel data. For providing both a higher resolution and a larger number of halftone levels for an output image at a low cost, an input image is decomposed into four color planes as CMYK data, and data on each color plane is compared with a dither matrix in a binarization circuit to be converted to binary data. The dither matrix generates a dither pattern composed of eight clusters having substantially the same shape as a kernel cluster capable of expressing 15 or more halftone levels. In this way, a smooth gradation having 120 or more halftone levels is realized by repetitively applying a small pattern having approximately 15 halftone levels.

Abstract: A color correcting method for a color image generating apparatus for overlapping 3 or 4 color materials according to color image data of 3 separated colors of yellow (Y), magenta (M) and cyan (C) or of 4 separated colors of Y, M, C and black (K) to obtain a multicolor image, wherein the apparatus includes a color detector, a test pattern is printed in a vertical/horizontal stripe form of 2-color combinations of 2 of the 3 or 4 colors and is measured by the color detector to find a hue value, a relative overlap deviation of the colors Y, M, C or Y, M, C, K is calculated from the found hue value, and an irradiation start position of a semiconductor laser in a main-scan direction and an irradiation start position of the semiconductor laser in a feed direction are controlled to correct the relative overlap deviation.

Abstract: In an elastic frictional member including: a core ring fitted on a sleeve fixedly mounted on a shaft; and an elastic element engaged with the outer cylindrical surface of the core ring, a plurality of small protrusions are extended from the outer surface of a lip forming a part of the elastic element; that is, from a slide surface of the elastic element which is in slide contact with the inner cylindrical surface of a shaft hole formed in the gear. The small protrusions of the lip are in point contact with the inner cylindrical surface of the shaft hole of the gear; that is, the outer surface of the lip from which the small protrusions are extended is spaced from the inner cylindrical surface of the shaft hole of the gear, thus allowing the formation of a lubricant film in the space. The lubricant film thus formed maintains the friction coefficient substantially constant.

Abstract: A storage device includes a partition wall dividing an interior of a casing into a disk chamber and a drive chamber. Recording disks are rotatably disposed in the disk chamber. Arms, each supporting a read/write head at a distal end portion thereof are capable of exteding into the respective spaces between the recording disks through an opening of the partition wall. An actuator is mounted within the drive chamber for linearly reciprocating the arms to cause the heads to skim across recording surfaces of the recording disks. An interrupting surface is formed on a portion of the partition wall at a downstream side of the arm with respect to an air flow due to the rotation of the recording disks, for interrupting the air flow to convert a dynamic pressure of the air flow into a static pressure thereof. With this arrangement, the air is prevented from flowing back from the drive chamber into the disk chamber.

Abstract: A storage device includes a partition wall dividing an interior of a casing into a disk chamber and a drive chamber. Recording disks are rotatably disposed in the disk chamber. Arms, each supporting a read/write head at a distal end portion thereof, are capable of extending into the respective spaces between the recording disks through an opening of the partition wall. An actuator is mounted within the drive chamber for linearly reciprocating the arms to cause the heads to skim across recording surfaces of the recording disks. An interrupting surface is formed on a portion of the partition wall at a downstream side of the arm with respect to an air flow due to the rotation of the recording disks, for interrupting the air flow to convert a dynamic pressure of the air flow into a static pressure thereof. With this arrangement, the air is prevented from flowing back from the drive chamber into the disk chamber.

Abstract: A rotating disk storage device has a plurality of disks fitted onto a spindle, transducers supported by transducer supporting means for movement in face-to-face relationship with surfaces of the disks, and drive means for causing the transducer supporting means to move in a predetermined direction. Separating means provides for separation of a disk housing for housing the disks and a drive-mechanism housing for housing a drive mechanism. The separating means has a first opening for allowing the discharge of gas for cooling the drive mechanism and a second opening for allowing the gas which has cooled it to be discharged via discharge means. The separating means has flow resisting means on the side of the disk housing so as to prevent the gas from flowing backward into the first and second openings.