Abstract: A low-voltage bias circuit for a photo-diode includes first and second bipolar transistors with a common base connection and grounded emitters, the photo-diode being connected between the emitter of the first transistor and ground in the reverse polarity direction. A current-mirror circuit uses as the reference current the collector current from the first transistor, which is essentially the photo-current, and produces a feed-back current through the base-emitter junction of the second transistor to hold the voltage across the photo-diode at a near zero value for a wide range in values of photo-current. Thus there is minimum delay in the response of the photo-current to step-functions of the incident light.

Abstract: The present invention relates to a light-sensing circuit used in a so-called light regulating type flash device to automatically control the amount of flash emitted. In the present invention, a flash photographing with an appropriate exposure is done, securing such flash amount as providing appropriate exposure always regardless of the position of an object in a photographing frame. This is done by making light-sensing for each of different zones independently using a plural number of light-sensing circuits for stopping the flashing by the output of the one light-sensing circuit reaching a prescribed level of output from the different light-sensing circuits.

Abstract: A circuit for integrating a quantity of light in an automatic control type flash unit having flash means for providing flash illumination comprises light responsive means, an amplifier circuit, a high-pass filter, a voltage-current conversion circuit and a capacitor. The light responsive means receives light resulting from the flash illumination and converts the received light into a corresponding electrical signal. The amplifier circuit puts out the electrical signal as an amplified voltage. This circuit also puts out DC and low frequency error voltages. The high-pass filter eliminates DC and low frequency error voltages from the voltage put out by the amplifier circuit and puts out only the voltage corresponding to the electrical signal. The conversion circuit puts out a current corresponding to the voltage put out by the high-pass filter. The capacitor is charged with the current from the voltage-current conversion circuit.

Abstract: A novel form of photoelectric conversion circuit including a photo sensor is provided, which is very limited in response time even at low illuminations and highly valuable for use in automatic cameras. It comprises a comparator for comparing the output voltage of the operational amplifier, connected to the photo sensor, with a reference voltage, and discharging means operable under the control of the comparator quickly to discharge the charge stored in a parastic capacitor of the photo sensor when the circuit is energized for operation.

Abstract: A light detector system includes a photo-diode being connected to an integrated circuit that includes a current-mirror amplifier. The current-mirror amplifier has a stable gain even down to the very low input currents that may be generated by a silicon photo-diode that is exposed to low levels of light intensity. The integrated circuit may also include the photo-diode itself as well as other circuitry for use in controlling the shutter speed of a camera to automatically provide the proper photographic film exposure.

Abstract: A pair of field effect transistors are series connected with one acting as a current source to bias the second which acts as a source follower. A photodiode, connected between the source follower gate and source, operates in response to light to change the current in the source follower. The photodiode is biased by the collector of a bipolar transistor that is connected as a negative feedback amplifier operating around the source follower stage. This configuration maintains close to zero bias on the photodiode, particularly at low light levels, and ensures that the collector current in the bipolar transistor equals the photocurrent. An output bipolar transistor with an uncommitted collector matches the feedback transistor and has its emitter and base directly connected thereto. Thus the output current will track the photocurrent, which is a linear function of light input over a very large range of levels. The circuit is linearly operative to extremely low light levels.

Abstract: A light measuring and indicating circuit utilizing indicating elements such as light-emitting diodes, to indicate corresponding light intensity levels. Intermediate levels are indicated without increasing the number of flip-flops employed in an activating circuit for the light-emitting diodes by intentionally causing the circuit to activate light-emitting diodes alternately. The activating circuit includes a reversible digital counter controlling the light-emitting diodes, two comparators for operating the counter reversibly in response to the comparison of light-dependent and standard signals, and a digital-to-analog converter which varies one or more of said signals in accordance with a counter output.

Abstract: A control device, adapted to automatically insert a proper correcting filter in a photographing light path dependent upon the color balance of the film used and the type of lighting conditions, is disclosed. Three signals are developed indicating, respectively, that the illuminating light is sunlight, incandescent light, and fluorescent light. The different types of light are detected by a pair of discriminators, one of which is based upon spectral content and the other of which is based on the presence of flicker. Incandescent light is distinguished from the other types of light by its unique spectral characteristic. Sunlight is distinguished from the other types by the absence of an a.c. flicker in such light. The three signals are applied to a mechanism which inserts the filters. A switching means is provided in-between the latter three signals and the filters so that the set of filters connected to be responsive to the three signals depends upon the color balance of the film used.

Abstract: A focus detecting photoelectric device herein disclosed is usable in a focus control system and is placed on an image plane where an optical image of a subject to be, for example, photographed through an objective lens assembly is focused to detect whether the image has been exactly focused or whether the image is out of focus. An output signal from the photoelectric device herein disclosed is used to control the focus control system to effect the desired focus control in relation to the objective lens assembly. To this end, the focus detecting photoelectric device is composed of at least one group of photoelectric elements, such as photodiodes, connected in series to each other with the cathode of one photoelectric element connected to the anode of the other photoelectric element. These photoelectric elements of the group may be formed on a semiconductor substrate in a predetermined pattern by the use of a known IC circuit making technique.

Abstract: A pair of photocells having substantially the same characteristics and directly connected in opposite relation to each other are used as a light receptor device which gives photometric input to the exposure control unit or regulator in a camera. According to this arrangement, the composite illuminance-output characteristic provided by the pair of photocells diverges from the usual proportional relation in the high illuminance range, and this feature is advantageously utilized for iris stops in cameras.

Abstract: The present invention relates to a photo-electric conversion element suitable for use in a system for detecting object image visibility and a method for detecting object image visibility employing the same and also relates to a device therefor. The photo-electric conversion element is characterized by having a first electrode at both ends of the direction along with a short side of a photo-semiconductor which has an extremely shorter short side as compared to its long side, and having a second electrode discretely formed at both ends of the direction along with its long side. Further an element with electrical characteristics being non-linear is connected to or formed at each of the above mentioned electrodes.

Abstract: An off-photometric-range indicating device for photometric circuits for cameras visually indicates to a photographer when the brightness of an object to be photographed is off the set photometric range of the photometric circuit. The indicating device includes a detection circuit to detect the brightness of the object and to produce an output signal when the detected value of the brightness is out of the photometric range of the photometric circuit, a switching circuit connected to the detection circuit and operated by said output signal, and a circuit connected to the switching circuit and actuated by the operation of the switching circuit to scale out the indicator, which may be visually observed by the photographer.

Abstract: An autoranging digital luxmeter is disclosed in which the current from a photocell is converted into a voltage by cascaded, variable gain amplifiers. The output of the amplifiers is coupled by a sample-and-hold circuit to an analogue-to-digital converter, the output of which is a digital representation of lux. The output of the amplifiers is also connected to limit comparison circuitry which, by way of an up-down counter, varies the gain of one or both of the amplifiers.

Abstract: A wireless multiflashlight apparatus simultaneously illuminates a subject by flashlight rays emitted from a main flashlight device mounted on a photographic camera and at least one additional flashlight device located at suitable position away from the main flashlight device. In the main flashlight device is provided a flash tube arranged to emit substantially two or more flashlight rays at a predetermined time interval therebetween upon the shutter operation of an associated camera. In the additional flashlight device are provided a decoder for producing an outlet signal only upon receipt of the flashlight rays from the main flashlight device through a photo-electric conversion element and an amplifier, and a flash tube operative to be triggered only by the output signal from the decoder. The additional flashlight device is protected from inadvertently flashing even upon reception of any flashlight rays from other flashlight devices than the associated main flashlight device.

Abstract: A remote flash slave apparatus for use in conjunction with a packaged linear array of flashlamps. The slave unit incorporates a solid state flashlamp selector circuit which is enabled or energized for only a limited period of time corresponding with the output interval of a typical flashlamp to preserve the integrity of the firing circuit. Additionally, the slave unit incorporates a feature providing for the avoidance of inadvertent cascading or firing of a series of flashlamps under a high steady-state light level environment.

Abstract: An off-photometric-range indicating device for photometric circuits for cameras visually indicates to a photographer when the brightness of an object to be photographed is off the set photometric range of the photometric circuit. The indicating device includes a detection circuit to detect the brightness of the object and to produce an output signal when the detected value of the brightness is out of the photometric range of the photometric circuit, a switching circuit connected to the detection circuit and operated by said output signal, and a circuit connected to the switching circuit and actuated by the operation of the switching circuit to scale out the indicator, which may be visually observed by the photographer.