Abstract: Capacitors (4, 6) are connected in series across a DC power supply (2). IGBTs (8, 10) are connected in series across the DC power supply (2), too. The IGBTs (8, 10) are rendered conductive alternately. A transformer (12) is connected between the junction of the capacitors (4, 6) and the junction of the IGBTs (8, 10). Snubber capacitors (32, 38) are connected in parallel with the IGBTs (8, 10), respectively. Diodes (34, 40) are connected in series with respective ones of the snubber capacitors (32, 38) in such a manner that said snubber capacitors (32, 38) can be charged when the IGBTs (8, 10) are rendered nonconductive. A secondary winding (54SA) of a transformer (54) is connected between the DC power supply (2) and the junction of the snubber capacitor (32) and the diode (34), and converts a secondary voltage of the transformer (12) and returns the converted voltage to the DC power supply (2) when the IGBT (8) is conductive.

Abstract: The present invention provides an optical amplifier for amplifying and outputting an input optical signal, and the optical amplifier comprises an erbium-doped optical fiber (EDF) (3), a laser diode (1), a WDM coupler (2), and a temperature setting control unit (8). A pumping light outputted from the laser diode (1) is divided at a given wavelength by the WDM coupler (2) to a light component on long wavelength side and a light component on short wavelength side, and these are separately outputted. Among these light components, the light component on long wavelength side is inputted to the EDF (3) as a forward pumping light. The light component on short wavelength side is inputted as a backward pumping light. The temperature setting control unit (8) sets a ratio of forward pumping light intensity to backward pumping light intensity and controls temperature of the laser light source according to the preset value.

Abstract: The present invention provides an optical amplifier for amplifying and outputting an input optical signal, and the optical amplifier comprises an erbium-doped optical fiber (EDF) (3), a laser diode (1), a WDM coupler (2), and a temperature setting control unit (8). A pumping light outputted from the laser diode (1) is divided at a given wavelength by the WDM coupler (2) to a light component on long wavelength side and a light component on short wavelength side, and these are separately outputted. Among these light components, the light component on long wavelength side is inputted to the EDF (3) as a forward pumping light. The light component on short wavelength side is inputted as a backward pumping light. The temperature setting control unit (8) sets a ratio of forward pumping light intensity to backward pumping light intensity and controls temperature of the laser light source according to the preset value.

Abstract: A camera has a function of determining whether a frame is exposed or unexposed by reproducing signals recorded on a magnetic-recording region of a film. When a film cartridge is loaded into the camera, the film is fed out therefrom. If it is determined that a noise having a level higher than a reference level is included in a reproduced signal read by a magnetic head, for reading the signals recorded on the magnetic-recording region, before the magnetic head reaches the magnetic-recording region, film feeding is stopped and a warning is issued.

Abstract: An apparatus having a judging device judges whether a film frame is exposed or not by detecting that a magnetically recorded signal exists or not on a magnetic recording section arranged correspondingly on each frame of a film. The device judges, when it is judged that one frame is an unexposed frame by detecting no recorded signal on the magnetic recording section, whether a following frame is exposed or not. And, if it is judged that the following frame is also an unexposed frame, it is judged that the previous frame is not exposed. Thus, an accurate judgment of an unexposed frame and film feeding of a head frame of unexposed frames to a photographing position can be achieved.

Abstract: A driving device, for driving a compensation lens of a camera, with a feedback control for an actuator therefor in which it is easy to keep a feedback cycle constant. In the feedback control, the feedback cycle is kept constant by counting the number of PWM pulses for driving the actuator. In case that the actuator is of a type in which it is controlled by more than one PWM pulse trains with different phases, one pulse train with predetermined phase is continuously supplied to the actuator even when the actuator is not driven, where the number of pulses in the one pulse train is counted so as to keep the feedback cycle constant. The actuator preferably employs a piezoelectric element which expands and contracts in response to a wave-form pulse included in the PWM pulse train.

Abstract: A position detecting apparatus, which is used in a shake correctable camera for detecting positions of an optical axis of a shake correction lens, corrects an error component of a first position sensor for detecting the position of the optical axis in a first direction which is, for example, the vertical direction is corrected by adding a correction value which is selected from a one dimensional table corresponding to the position of the optical axis in the second direction which is for example, the horizontal direction.

Abstract: An inverter includes a series circuit of two current conducting units connected between two input terminals adapted to be connected to a DC power supply. Two first capacitors are connected in series between the two input terminals. A primary winding of a transformer is connected between the junction of the current conducting units and the junction of the first capacitors. Each of the current conducting units includes a parallel circuit of an IGBT, a diode and a second capacitor. The IGBT has a collector, an emitter and a gate and is rendered conductive when a control signal is applied to the gate while a voltage of a predetermined polarity is applied between the collector and the emitter. The diode is connected in inverse parallel with the IGBT. An inverter control circuit applies alternately the control signals to the respective IGBTs with a predetermined quiescent period disposed between the respective control signals applied.

Abstract: A DC power supply apparatus includes an input-side rectifier which rectifies an input AC voltage and supplies the rectified voltage to a voltage-boosting converter. The voltage-boosting converter converts the supplied voltage to a voltage of a predetermined magnitude. The predetermined magnitude voltage is, then, converted to a high-frequency voltage by an inverter and applied to a primary winding of a transformer. An output-side rectifier rectifies a high-frequency voltage induced in a secondary winding of the transformer. The inverter includes IGBTs and diodes, which are connected in a full-bridge configuration. A capacitor is connected in parallel with each IGBT. When the IGBTs are rendered conductive by the charging and discharging of the capacitors, no current flows through the IGBTs, and when the IGBTs are rendered nonconductive, the voltages applied to the IGBTs are made to become zero.

Abstract: A wavelength within an amplifying wavelength band of an optical amplifier is introduced into the optical amplifier at all times or when an interruption and/or reduction of a ray of input light is detected. When the interruption and/or reduction of the input light is detected, an output of the excited light is interrupted or reduced, an optical switch is controlled so that the input light is interrupted, and after the input light is restored, a transmittivity of the optical switch is progressively increased or the input light is passed for a constant period of protection time. Thus, when the input light has been restored, a light surge may be reduced without any adverse affect of a reverse distribution of the optical amplifier. In the case where the input light is abruptly raised during a period of moderation of the excited level, it is possible to suppress the light surge caused by the long service life due to the natural discharge of the excited level.

Abstract: A camera (100), suitable for using photographic film (18) with a magnetic track (33), includes a transporting mechanism (M, 22) for transporting the film along a film transport path, a magnetic head (11) positioned adjacent the film transport path so as to read information magnetically recorded on an adjacent portion of the magnetic track, signal processing circuits (12, 42) to provide a digital output signal responsive to thus read information, and a microcomputer (13) for comparing a digital output signal to predetermined threshold levels in order to determine whether or not information is recorded on the portion of the magnetic track being read by the magnetic head and for setting the threshold values. The threshold levels can be set in accordance with a level of the digital output signal when magnetically recorded information is not being read by the magnetic head, e.g., before the film is fed or during the feeding of the film before the first frame reaches the magnetic head.

Abstract: A judging device for judging an unexposed frame of a film having a magnetic recording portion recordable with a magnetic signal, includes: a magnetic header for scanning the magnetic recording portion; a divider for dividing the magnetic recording portion into a plurality of blocks; a first judger for judging whether blocks bear a magnetic signal block by block; and a second judger for judging whether the frame corresponding to the magnetic recording portion has been exposed.

Abstract: An in-line optical amplifier includes a pumping source, a rare-earth element doped fiber amplifier, a gain regulator and a noise detector. An input power and an output power of the in-line optical amplifier are detected from the input optical signal and the output optical signal, respectively, and then they are used to detect a resultant gain of the in-line optical amplifier. The gain regulator controls the pumping light emitted by a pumping source such that the gain of the rare-earth element doped fiber amplifier is increased and a gain deviation of the resultant gain from a predetermined gain is reduced. The noise detector detects an internal noise or a noise figure based on the gain deviation, for example, by detecting the intensity of the pumping light or the magnitude of drive current of the pumping source.

Abstract: A microcomputer provided in a camera body uses a data signal read by sensors facing the data disk of a film cartridge as a positional signal to set the stop position of the spool for providing exposed/unexposed indication to the film. The voltage of the power supply of the camera is detected to modulate a pulse duration by which the number of rotations of the motor can be kept constant in rewinding the film. The sensors are disposed upstream in the rotational direction of the data disk by a certain angle .theta. with respect to the point at which the spool is stopped in order to prevent the dislocation between the display mark of the cartridge and the pointing mark of the data disk. The microcomputer discriminates whether or not data has been read. The mechanism for feeding the film is controlled to set the film at a predetermined position after the decision that the data has been read.

Abstract: A multi-repeater optical transmission system comprises a plurality of repeaters which are respectively provided with oscillators for generating oscillation waves of different frequencies. The respective oscillation waves are frequency-modulated according to repeater information signals respectively generated in the repeaters. According to the frequency-modulated oscillation waves, respective pumping sources are operated to emit pumping lightwaves for pumping Er-doped fiber amplifiers. The respective pumping lightwaves carrying the repeater information signals are sent out to a transmission line through a wavelength division multiplexing fiber coupler.

Abstract: A vehicle steering wheel is provided with a shock-absorbing device collapsibly mounted in the center pad for absorbing shock energy generated upon a vehicle collision. The shock absorbing device comprises a honeycomb core structure preferably of steel or aluminum which has its core walls disposed in a direction in which shock energy is exerted. The honeycomb core structure has a cell size, a core wall thickness and a core height all selected to demonstrate a maximum shock-absorbing performance.

Abstract: A magnetic roller is fixedly mounted in a developing device provided in an image forming apparatus. The magnetic roller includes a magnetic member, which is made of a mixture of ferromagnetic material and polymeric compound. A plurality of magnetic poles are formed along the periphery of the magnetic member and consist of a main magnetic pole confronting an electrostatic latent image support member of the image forming apparatus, at least two magnetic poles formed adjacent to each other on one side of the main magnetic pole and having a polarity opposite to the polarity of the main magnetic pole, and at least two magnetic poles formed adjacent to each other on the other side of the main magnetic pole and having a polarity opposite to the polarity of the main magnetic pole.

Abstract: A precision casting device especially suitable for dental use, which includes melting and casting chambers supported by a frame such that they are arranged coaxially up and down in the frame under a normal operating state and can be drawn horizontally out of the frame during service time in order to facilitate access to the interiors of them, and which is provided with evacuating apparatus and an inert gas supply and can carry out the casting process in which a casting material is molten in an inert atmosphere, the molten material is then supplied to a mold in a vacuum state and, therafter, casting is effected under a pressure of inert atmosphere.