Abstract: A printer buffer unit is connectable to one or a plurality of host computers and one or a plurality of printers. The printer buffer unit has a unit for detecting a break of print job data sent from a host computer, and a unit for adding a job offset command at the time of the break in sending the print job data to a printer.

Abstract: A printer buffer unit is connectable to one or a plurality of host computers and one or a plurality of printers. The printer buffer unit has a unit for detecting a break of print job data sent from a host computer, and a unit for adding a job offset command at the time of the break in sending the print job data to a printer.

Abstract: An apparatus for generating a laser beam modulated on the basis of an information signal, which comprises a circuit for generating a first information signal, a circuit for generating a second information signal, independent of the first information signal, a circuit for driving a semiconductor laser on the basis of the first and the second information signals, wherein the driving circuit comprises first and second switching elements which operate supplementarily with each other, one of the first and second switching elements switches a drive current to the semiconductor laser, and wherein the first information signal is provided into a control terminal of the first switching element and the second information signal is provided into a control terminal of the second switching element.

Abstract: An apparatus using a semiconductor laser comprises a measuring unit for measuring a slope efficiency of the semiconductor laser; a determination unit for determining whether or not the measurement value reaches a specified value; and a notification unit for notifying the determination result of said determination unit.

Abstract: Disclosed is a recording system in which an operation performed on the side of a printer unit in order to change over recording density is delayed while a recording operation is in progress. When a recording density changeover command is received during a recording operation, the density changeover is performed after the recording operation ends. A control unit which controls the printer unit is informed of the fact that the measures for changing over the recording density have been completed on the printer unit side.

Abstract: A power supply device converts an input voltage to a transformer to high output voltages at a secondary side. A transistor is connected in parallel with each of two or more series-connected high voltage output circuits of different polarities on the secondary side. The base currents of the transistors paralleled with the output circuits are controlled so that the high voltage output can be continuously varied.

Abstract: An apparatus for generating a laser beam modulated on the basis of an information signal, which comprises a circuit for generating a first information signal, a circuit for generating a second information signal, independent of the first information signal, a circuit for driving a semiconductor laser on the basis of the first and the second information signals, wherein the driving circuit comprises first and second switching elements which operate supplementarily with each other, one of the first and second switching elements switches a drive current to the semiconductor laser, and wherein the first information signal is provided into a control terminal of the first switching element and the second information signal is provided into a control terminal of the second switching element.

Abstract: The invention provides an interunit communication system which comprises a main unit and a plurality of subunits and executes a communication between the units by a microcomputer of each unit. The system comprises: power producing means, provided for each subunit, for producing a driving power for the microcomputer of the subunit by a power which is supplied from the main unit through a power line; resetting means, provided for each subunit, for resetting the microcomputer of the subunit in the case where the power supply was restarted after the power supply from the main unit had been shut off; detecting means, provided for the main unit, for detecting a runaway of the microcomputer of the subunit on the basis of a reception state from a signal line for communication; power shut-off means, provided for the main unit, for shutting off the power supply to the subunit when the detecting means detects the runaway of the microcomputer; and power restarting means for restarting the power supply to the subunit.

Abstract: An image forming apparatus includes recording structure for recording an image on a recording medium, first and second conveying structures for conveying the recording medium to the recording structure, detecting structure for detecting a plurality of multi-fed recording media fed by the conveying structure, and control structure for controlling the first and second conveying structures so that an image is recorded on a recording medium separated from the multi-fed recording media and detected by the detecting structure or discharged from the image forming apparatus.

Abstract: An image forming apparatus includes a movable image bearing member; an image forming device for forming an image on the image bearing member; a transfer device for transferring an image from the image bearing member onto a recording material at a transfer position; a detector for detecting a recording material conveying passage from a recording material feeding station to the image transfer position; and a controller responsive to the detector to form blanks at a leading and trailing edges of the recording material by controlling image forming operation of the image forming device.

Abstract: A temperature control device for controlling a surface temperature of a member to be heated at a predetermined temperature includes a detector for detecting the surface temperature, and a control unit for controlling current supply for a heating source for heating the member to be heated so that a result of detection by the detector is maintained at a predetermined value. The control unit controls a time of current supply for the heating source during a constant temperature control according to data relating to peak temperatures of the surface temperature during the constant temperature control.

Abstract: In a power supply circuit for a motor in which a power source line can be opened and closed by a first opening-closing device, a construction is adopted which has a electrically controllable second opening-closing device connected in parallel to the first opening-closing device, a comparator for comparing the voltage of the motor load side with a predetermined value, a controller for controlling the opening and closing of the second opening-closing device on the basis of a signal from the comparator, and a current limiter device provided in parallel to the second opening-closing device, whereby a rush current when the first opening-closing device is closed can be suppressed to thereby prevent the fluctuation of the source voltage and the deterioration of the contacts of the first opening-closing device.

Abstract: An image forming apparatus includes an image forming device for forming an image on a recording material, the image forming device including an image bearing member, a movable charging member for charging the image bearing member and a power source for supplying electric power to the charging member; a constant current controller for supplying the charging member with a predetermined constant level of electric current; and a second controller for controlling an image forming condition by the image forming device on the basis of plural voltage provided at different points of time during a constant current control operation with the same constant current level by the constant current controller.

Abstract: A positioning apparatus for positioning a reciprocally movable member, such as a guide member for a sheet of recording paper, between a reference position and a predetermined position. The apparatus includes a detector for detecting that the movable member is in the proximity of the reference position, and a counter for counting the amount by which the movable member is shifted while the detector is detecting that the movable member is in the proximity of the reference position. A controller stores the value counted by the counter, and controls drive of the movable member when the movable member is being returned to the reference position based on the count in the counter and the stored count value. A second counter may be provided to count the amount by which the movable member is shifted from the reference position to the predetermined position.

Abstract: A light quantity control device suitable for use in a laser beam printer includes a beam generator, a monitor for monitoring the quantity of light of a beam generated by the beam generator, and a controller. The controller controls the light quantity of the beam generated by the beam generator in response to the output of the monitor. The controller includes a digital value output circuit and a light quantity control circuit. The digital value output circuit outputs a digital value representing the quantity of light of the beam, and the light quantity control circuit controls the quantity of light in response to the digital value. The digital value output circuit varies the timing of output of the digital value in accordance with the output of the monitor.

Abstract: A driver for a light emitting device comprises first and second switching means associated with the light emitting device and application means for applying voltages to the first and second switching means to perform the switching operation in accordance with an input signal. The application means applies voltages of essentially same level to the first and second switching means.

Abstract: This invention relates to an image forming apparatus having a convey path comprising lateral movement apparatus for controlling a widthwise position of a sheet member to be conveyed, wherein the lateral movement apparatus is curved in a convey direction.

Abstract: A light quantity control device suitable for use in a laser beam printer. A controller varies the quantity of light emitted by a semiconductor laser so as to maintain a constant light quantity, regulating the rate of variation of the light quantity according to the output of a monitor for detecting the quantity of light emitted from the semiconductor laser.