Seiko Instruments Inc

Gakkouhoujin Chikoujigakuen

Toshiyuki Uchida

Satoshi Machida

Minoru Ariyama

Atsushi Igarashi

Hirokazu Yoshizawa

Akira Takeda

Ryoichi Anzai

Toshihiko Omi

Isamu Fujii

Yuji Wakabayashi

Provided is a photodetector device for detecting light intensity based on a detection signal of a difference circuit, the photodetector device including: a first light receiving element which generates an electric charge based on incident light; a second light receiving element, which includes a light blocking part for blocking incident light and generates an electric charge being a reference; and a storage detection circuit for detecting that an output voltage of the first light receiving element or the second light receiving element has reached a predetermined potential and outputting the detection signal when the difference does not reach a predetermined value even though sufficient incident light is provided.

Photodetector device

Provided is a switched capacitor amplifier capable of outputting a stable output voltage. The switched capacitor amplifier is capable of operating so as to eliminate a charge/discharge time difference between an input capacitor () and an output capacitor (). Accordingly, in a shift from a hold state to a sample state, for example, even if one terminal voltage (V) of the output capacitor () abruptly increases to an output voltage (VOUT), another terminal voltage (Vs) of the output capacitor () does not increase abruptly. In other words, an input voltage to an internal amplifier () does not increase abruptly. Therefore, an output voltage of the internal amplifier () becomes stable and accordingly the output voltage (VOUT) becomes stable as well.

Switched capacitor amplifier

Provided is a photodetection device which is small in size and has excellent sensitivity. A photodetection device puts cathode terminals of photodiodes having different spectral characteristics into an open end state, and detects light intensity of a desired wavelength region according to a difference in electric charges that have been stored in those photodiodes in a given period of time. The photodiodes employ a system of storing electric charges, and hence even if a photocurrent is small, the photocurrent may be stored to obtain the electric charges required for detection, and the downsizing and high detection performance of a semiconductor device that forms the photodiodes may be achieved. Further, a wide dynamic range may be realized with an electric charge storage time being variable according to the light intensity, to intermittently drive an element required for difference detection at the time of difference detection so as to suppress electric power consumption, or to average the output so as to reduce flicker.

Optical detection device, and image display device

Provided is a comparator circuit that is capable of operating at high speed and canceling an offset voltage with high precision. The comparator circuit includes a second amplifier circuit for amplifying an output of an amplifier circuit and feeding back the amplified output to an input of the amplifier circuit. When the comparator circuit samples the input voltage, the second amplifier circuit conducts feedback and increases a gain to cancel the offset. Also, when the gain of the amplifier circuit is made lower than the gain of the second amplifier circuit, and the comparator circuit compares the input voltage, the comparing operation can be conducted at high speed by separating the amplifier circuit from the feedback of the second amplifier circuit.

High speed comparator circuit with offset cancellation

Provided is a chopper amplifier circuit capable of eliminating an influence of a slew rate of an amplifier and suppressing spike generation to thereby obtain an output signal having little harmonic distortion. The chopper amplifier circuit according to the present invention includes: a first chopper circuit for chopping an input signal by a first pulse and a second pulse shifted from each other in phase by a half cycle, switching a relation of connection between an input terminal pair and an output terminal pair at a timing of the chopping, and outputting the input signal as a modulated signal; an amplifier for amplifying the modulated signal and outputting the modulated signal thus amplified as an amplified signal; a first sample hold circuit for holding the amplified signal at the first pulse and outputting the amplified signal at the second pulse; and a second sample hold circuit for holding the amplified signal at the second pulse and outputting the amplified signal at the first pulse.

Amplifier circuit

Provided is a chopper amplifier circuit capable of reducing an offset voltage of a sensor bridge and temperature characteristics of the offset voltage. An offset adjusting voltage generation circuit for generating a voltage equal to an offset voltage of a sensor bridge and an offset temperature characteristics adjusting voltage generation circuit for generating a voltage having temperature characteristics equal to those of the offset voltage are provided. These output voltages are chopper-modulated and subtracted from a chopper-modulated output signal of the sensor bridge.

Growing community of inventors

Chiba, Japan

Toshiyuki Uchida