Abstract: A controller for controlling the output intensity of a semiconductor laser used in a laser printer or the like in such a manner that the desired adjustment value is obtained, even in the presence of noise in a signal P.sub.D indicating the value of the detected intensity. An adjustment value is provided depending on the results of a comparison between the signal P.sub.D and a set value P.sub.S. The adjustment value is decreased when P.sub.S <P.sub.D and increased when P.sub.D <P.sub.S. The current through the semiconductor laser is adjusted in accordance with this set value.

Abstract: A device for detecting and communicating the occurrence of malfunctions occurring in an optical unit of a laser printer or the like wherein the number of terminals needed for communicating multiple malfunction-indicating signals is reduced to one. Various malfunctions are indicated by signals of respective different frequencies. The pulse width of the single signal thus composed is detected to determine in an external processor the type of malfunction.

Abstract: An apparatus for controlling an optical output from a semiconductor laser for use in a laser printer, designed to complete the emission intensity control in a short time and to prevent deterioration and thermorunaway even when a noise occurs, while enabling confirmation of whether or not the emission intensity control is completed without any abnormality. The intensity of emission from the semiconductor laser is compared with a reference value, and a current supplied to the semiconductor laser is changed in certain regular cycles is response to the result of comparison. Strobe signals are supplied in, for instance, the same cycles and the results of comparison are successively stored in a storage device of more than two bits by the timing corresponding to the strobe signals. An APC completion signal is output when the stored results of comparison exhibit successive inversions and when the current detection value is lower than the reference value.

Abstract: An emergency reset circuit is provided for interrupting the light output of a modulatable laser of a laser beam printer (LBP) that produces a hard copy of image information by copy-processing a photosensitive surface scanned by the laser when it is supplied with a preset driving current and produces light at a preset level. The laser is operated by a control system that produces a preselected driver voltage that is applied to a laser driver circuit that supplies driving current to the laser. The driver circuit is responsive to the preselected driver voltage for producing said preselected laser driving current whereby the laser to operate at its preset level. The emergency reset circuit includes a latch circuit responsive to an emergency reset signal for zeroing the drive voltage, and an offset circuit for supplying a preselected offset voltage to the laser driver circuit when the driver voltage is zeroed.

Abstract: A drive circuit for a semiconductor laser in a laser printer in which the laser output is sampled and compared with a reference signal. The reference signal is varied to compensate for temperature changes of the entire drive circuit, especially the semiconductor laser. The comparison signal then controls the size of the drive current to the laser. This drive current is modulated by the image data.

Abstract: A semiconductor laser drive circuit in which a constant current circuit responds to the voltage developed by the constant current across a grounded resistor and in which a buffer circuit, such as a base-grounded transistor, is interposed between the source of the constant current and the laser.

Abstract: The present invention provides an intensity control device for a laser in a laser beam printer that produces a hard copy of image information by copy-processing a photosensitive surface scanned by the laser while it is in a scanning mode during which the laser is modulated by the image information. The intensity control device according to the present invention stores a first representation of a present light intensity of the laser during its non-scanning mode. It further stores a second representations of a user selected image density for a hard copy produced by the printer. The first and second representations are combined for forming a control voltage during a non-scanning mode of the laser. Finally, a current is produced that is supplied to the laser in response to the control voltage such that the intensity of light produced by the laser is dependent on both the first and second representations.

Abstract: An automatic exposure camera in which any one of four modes, specifically, an aperture-priority automatic exposure mode, a shutter-speed-priority automatic exposure mode, a programmed automatic exposure mode and a manual exposure mode, can be readily set with reduced danger of improper selection. An automatic/manual switch is operated in association with a lens aperture ring to select one of an automatic aperture mode and a manual aperture mode for a lens of the camera. A mode A counter responds to the output of the automatic/manual switch to be made active when the automatic aperture mode is selected, and a mode M counter responds to the automatic/manual switch to be made active when the manual mode is selected. The output of one of the mode A counter and the mode M counter is selected for counting signals from the up or down switch to thereby set the exposure mode according to a count value so obtained.

Abstract: A manual aperture value setting circuit for a camera in which digital values corresponding to the full-aperture value and the minimum aperture value of a lens mounted on a camera are applied from the lens in digital form to a logic circuit which operates so that, with the range of aperture value set on the side of the camera being maintained in the aperture value range of the lens, the aperture value which has been set is changed to the full-aperture value or the minimum aperture value of the lens when it is out of the aperture value range of the lens.

Abstract: A photographing mode selecting circuit for a camera having a very low power consumption. A mechanical switch is provided for each possible photographing mode of the camera. Each mechanical switch is coupled in series with a resistor and an analog switch between the power source terminals. The analog switches are periodically pulsed to close them, thereby allowing current to flow through the corresponding resistor and mechanical switch if the mechanical switch is closed. The outputs formed at the junctions between the analog switches and the resistors are applied to flip-flop circuits for storage.

Abstract: A device for controlling a light source in a viewfinder of a camera, such as may be used for illuminating a liquid crystal display unit, having a simple operation and which is saving of power. An operating switch is provided for operating the light source. A timer is initiated when the operating switch is turned off. The light source is maintained turned on while the operating switch is turned on and while the timer is operating, and the light source is turned off when the operating switch is turned on during the operation of the timer.

Abstract: In an automatic diaphragm stop down operation square wave pulses are generated, the number of which represents the extent of diaphragm stop down. Short pulses are generated responsive to the leading and trailing edges of the square wave pulses. The short pulses are counted. After a predetermined number of short pulses are counted, diaphragm stop down is arrested. In one embodiment, when a periodic input signal representative of the extent of diaphragm stop down rises above a first threshold, the square wave pulses are produced at a first level and when the input signal drops below a second threshold lower than the threshold, the square wave pulses are produced at a second level.

Abstract: A multi-layer flexible printed circuit board assembly, having at least two flexible printed circuit boards with electrical conductive layers piled one on another. The conductive layers face in the same direction and a portion of the lower flexible printed circuit board is not covered with the upper flexible printed circuit board. Hence, some of the lead wires of an electronic component can be connected to the electrical conductive layer of the upper flexible printed circuit board, and the remaining lead wires can be connected to said electrical conductive layer of the lower flexible printed circuit board. The portion of the lower flexible printed circuit board which is not covered by the upper flexible printed circuit board is raised so that the surface of a copper foil layer on the upper flexible printed circuit board is substantially flush with the surface of a copper foil layer on the lower flexible printed circuit board.