Abstract: A wireless slave electronic photoflash device is located separately from a camera body, and responsive to light emission of a master electronic flash unit built in or connected to the camera body, for emitting light synchronized therewith. The slave flash device includes a discharge tube, a trigger section responsive to a trigger signal for causing the discharge tube to emit light, a photodetector adapted to detect an optical signal from the master flash device, a one-shot section which is retriggerable and generates and issues a signal during a predetermined time period in response to the receipt of a signal from the photodetector, and a trigger signal output section which generates and issues the trigger signal based on the signal from the one-shot section and the signal from the photodetector.

Abstract: A power supply circuit includes a booster circuit for boosting an output voltage from a power supply battery to predetermined positive and negative voltages, respectively. A main capacitor is charged by the predetermined positive or negative voltage boosted by the power supply circuit. In a discharge tube, a discharge current flows on the basis of the charge built up on the main capacitor, so that flash light emission is performed. A MOS controlled thyristor (MCT) is inserted in the loop of the discharge current from the main capacitor. A control circuit ON/OFF-controls the MCT by selectively applying the predetermined positive or negative voltage from the power supply circuit to the gate terminal of the MCT.

Abstract: A wireless flash photographing system prohibits flash light reception for a predetermined time period when it is determined that received flash light is not an identification signal. Light emission for pre-confirming a shade and main light emission are switched by the identification signal. A flash device applied to this system comprises a power supply circuit section, a light emission section, a control section and a light receiving circuit section. The light emission section comprises a series circuit including a main capacitor, a discharge tube, a diode and an IGBT, a voltage doubler circuit including resistors and a capacitor, and a trigger circuit including a trigger transformer and a trigger capacitor. The light emission section controls the IGBT to start/stop light emission.

Abstract: A camera system includes a camera main body, a transmitter for transmitting a signal to a flash device, a single communication path between the camera main body and the flash device, and a receiver for receiving a signal from the transmitter. The signal received by the receiver is selectively switched by a selector in the receiver in accordance with communication control data or emission control data with respect to the flash device. The selector switches the communication path to the emission control side only when data representing that the communication path is used as a signal path for emission control data with respect to the flash device is transmitted.

Abstract: A plurality of lens groups are movable in the direction of an optical axis. A plurality of motors are provided for the lens groups, respectively, so as to drive the lens groups. A focusing distance detector detects the position of a lens group which is one of the lens groups and which is changed in position in accordance with a change in the focusing distance, and outputs focusing distance data in accordance with the data representing the detected position of the lens group. A lens position detector detects the positions of the lens groups other than the lens group. A memory stores positional relationships between the predetermined lens group and the other lens groups. A zooming operation member is used for commanding a zooming operation.

Abstract: A plurality of lens groups are moveable in the direction of an optical axis. A plurality of motors are provided for the lens groups, respectively. A driving circuit drives the motors. A switching section sequentially selects the motors and connects the selected motors to the driving circuit. A lens position-detecting section detects the positions of the lens groups. A driving control section sequentially drives the lens groups in accordance with intermediate target position data, respectively, via the switching section and the driving section, and determines whether the lens groups have reached their respective intermediate target positions, on the basis of the detection performed by the lens position-detecting section. When the driving control section determines that the lens groups have reached their respective intermediate target positions, it demands next intermediate target positions, which are slightly away from the initially-determined intermediate target positions.

Abstract: A circuit for driving an ultrasonic motor which is driven by being applied with multi-phase alternating voltages comprises: a digital oscillator for providing a signal having a frequency higher than that of said alternating voltages; a frequency divider for dividing the frequency of the output signal of the digital oscillator into a desired frequency to provide a basic clock signal; a plurality of presetting circuits, each of independently presetting a delay time for generating a plurality of delay clocks which are delayed with respect the basic clock by different delay times; a plurality of delay circuits, each connected with a respective one of the delay time presetting means for generating a plurality of different delayed clock which are delay with respect to said basic clock by different periods of delay time in accordance with the preset delay time; and voltage generators which generates multi-phase alternating voltages from the basic clock and plurality of the delayed clocks for applying the multi-phase