Abstract: In a disk device, a focus servo activating circuit causes an RF amplifier 3 to amplify a focus error signal within a predetermined gain adjusting range, causes a control circuit 4 to multiply the amplitude of the focus error signal obtained by the RF amplifier 3 by two coefficients to calculate two threshold values, and starts up a focus servo upon the amplified focus error signal passing the two threshold values. The focus servo can be started up normally even for optical disks of extremely low reflectivity.

Abstract: In a disk device, a focus servo activating circuit causes an RF amplifier 3 to amplify a focus error signal within a predetermined gain adjusting range, causes a control circuit 4 to multiply the amplitude of the focus error signal obtained by the RF amplifier 3 by two coefficients to calculate two threshold values, and starts up a focus servo upon the amplified focus error signal passing the two threshold values. The focus servo can be started up normally even for optical disks of extremely low reflectivity.

Abstract: The present invention provides a sheet feeding apparatus with a feeding roller for feeding sheets; a friction member arranged at a position where a leading edge of the sheet fed by the feeding roller is abutted against the friction member and inclined with respect to a sheet feeding direction, the friction member being adapted to separate the sheets one by one by applying a friction force caused by contacting the leading edges of the sheets along lines to the sheets; and a guide member arranged at a same side as the friction member with respect to a sheet feeding path, and adapted to guide the leading edge of the sheet to a predetermined position on the friction member.

Abstract: In a dynamic pressure bearing apparatus for use in a rotary polygonal mirror type light deflector in a laser beam printer, a rotary head in a video tape recorder and the like, the apparatus includes a rotary shaft having a shaft end surface, a sleeve for rotatably supporting the rotary shaft through fluid, and a generator for generating dynamic pressure in a thrust direction. The sleeve has an end portion with a thrust receiver surface opposed to the shaft end surface. The dynamic pressure generator is formed on the thrust receiver surface. One of either the shaft end surface and the thrust receiver surface is convexly shaped for tolerating a non-flat surface of the shaft end surface and the thrust receiver surface.

Abstract: This invention relates to a sheet feeding apparatus with a support for stacking sheets; feeding roller for feeding out sheets stacked on the support; a plurality of urging members for urging the stacked sheets against the feeding roller; and a stopper for releasing at least one of the plurality of urging members from urging against the stack of sheets whenever the amount of sheets is less than a predetermined level.

Abstract: A sheet conveyer having a sheet registration device for an image forming apparatus having a sheet path for guiding a sheet having an image recorded on one side thereof back to an image forming unit for recording another image on the other side, comprises a mechanism for switching the sheet having the image recorded on one side thereof back to the sheet path, a mechanism for abutting the switched-back sheet against a lateral registration reference plane, and a preliminary shift function shared by the switch-back mechanism for shifting the sheet oppositely to the reference plane.

Abstract: A sheet material separating device has a rotatable conveying member for conveying sheet materials in a predetermined direction, a separating member opposed to the rotatable conveying member and prohibiting passage of the sheet materials other than the sheet material which is in direct contact with the rotatable conveying member and conveyed thereby, and a support member for supporting the separating member so that the position of contact between the rotatable conveying member and the separating member is changeable in the direction of conveyance of the sheet materials.

Abstract: A sheet obliquely conveying apparatus is provided with a pair of sheet conveying rollers including a forwardly and reversely rotatable drive roller and a follower roller rotatable in contact with the drive roller, and bearing structure for rotatably supporting the shaft of the follower roller. The dimension of the bearing portion of the bearing structure which supports one end of the shaft of the follower roller is greater generally along the direction of conveyance of a sheet material than the dimension of the bearing portion of the bearing structure which supports the other end of the shaft of the follower roller. The apparatus is further provided with a resilient device generally parallel to the direction of conveyance of the sheet material for pressing the shaft of the follower roller.

Abstract: A safety device for use in a recording apparatus controls the on/off operation and prevents the malfunction of motors for driving a gear flange to rotate a light sensitive drum and for driving an actuating gear and other driving members in accordance with a signal indicative of the reference rotational frequency received from an oscillator and a signal indicative of the rotational frequency of each motor. A motor control circuit is used including motor drivers for controlling the operation of said motors and a fault detection circuit for detecting the malfunction of said motors by comparing an adder output indicative of said motors' rotational frequencies with threshold values in a comparator, thereby ascertaining the long-term use of the light sensitive drum.

Abstract: Disclosed is a sheet material feeding device which has a first row of sheet materials comprising a number of sheet materials moved in the direction of arrangement and provided in the form of a row and a second row of sheet materials disposed in proximity to the first row of sheet materials and which is for converging these two rows of sheet materials into a single row of sheet materials. Accelerating apparatus is disposed in the first row of sheet materials and at this position, a sheet material of the first row of sheet materials is moved at a higher speed than the succeeding sheet material to thereby enlarge the interval between the two sheet materials, and accelerating apparatus for feeding a sheet material of the second row of sheet materials into the enlarged interval is disposed in the second row of sheet materials.

Abstract: A photosensitive medium driving apparatus comprises a photosensitive medium driven rotatable in the circumferential direction at a uniform peripheral speed, a driving source for rotating the photosensitive medium, and a supporting member for supporting the photosensitive medium for movement in the axial direction of the medium, wherein the photosensitive medium is movable in the axial direction in relation to the rotation of the medium.