Ricoh Company, Ltd.

Takeshi Nagahisa

Hirofumi Watanabe

Katsuhiko Aisu

Yasukazu Nakatani

Two types of high-pass filter circuit and a band-pass filter circuit are provided. Both types of high-pass filter circuit include a capacitor configured to input an input signal, a resistor connected between an output terminal of the capacitor and a prescribed bias voltage, and a signal output circuit connected to the output terminal of the capacitor and configured to buffer-amplify the input signal for output. In one of the two types of high-pass filter circuits, the resistor is formed on an SOI semiconductor substrate and includes two PN junction diodes that are inversely connected to each other in parallel. In the other one of the high-pass filter circuits, the resistor is formed on an SOI semiconductor substrate and includes two MOS transistors that are inversely connected to each other in parallel.

High-pass filter circuit and band-pass filter circuit

A semiconductor integrated circuit includes an acquisition unit configured to acquire a value outputted from an infrared sensor in response to an infrared ray received from an object, and a value outputted from a temperature sensor as a function of measured temperature of the infrared sensor; a second-temperature identification circuit configured to identify a second temperature which is a temperature of the object when the temperature of the infrared sensor corresponding to a measured value which is the output value of the infrared sensor, is the first temperature, by referring to the correspondence; a third-temperature identification circuit configured to identify a third temperature which is the temperature of the infrared sensor in outputting the measured value; and a calculation circuit configured to calculate a fourth temperature which is a temperature of the object on the basis of the first temperature, the second temperature, and the third temperature.

Semiconductor integrated circuit

A chopper amplifier includes a chopper modulator to modulate a certain detection signal and a bias voltage by a certain control signal and output a chopper modulation signal, a first differential amplifier to differentially amplify the chopper modulation signal from the chopper modulator and output a differential modulation signal, a chopper demodulator to demodulate the differential modulation signal from the first differential amplifier by the control signal and output a demodulation signal, a second differential amplifier to extract a detection signal component from the demodulation signal, and a plurality of filters connected at an input terminal of the second differential amplifier and having different cutoff frequencies from each other relative to the demodulation signal.

Chopper amplifier

A signal amplification circuit includes an input terminal; a first chopper modulation circuit; a first amplifier having an amplification circuit and a chopper demodulation circuit, a capacitance feedback circuit having a second chopper modulation circuit, a first switch constituting a voltage follower circuit with the amplification circuit; a second switch; a second amplifier to convert the differential output signal from the second output terminal into a single-end signal; and a filter to pass at least a predetermined frequency component of the chopping frequency from the single-end signal from the second amplifier to output an output signal of the signal amplification circuit.

Signal amplification circuit and signal amplification determination circuit including the signal amplification circuit

An infrared sensor device includes a plurality of infrared sensors that is provided in a plurality of divided areas in which an infrared-receiving area is radially divided in one plane; a detector that detects presence or absence of movement of an object in the infrared-receiving area for each of the divided areas based on an output of the infrared sensor; and a determiner that determines whether the object is in a detection area in a predetermined distance range from the infrared sensor, based on an arrangement pattern of the divided areas in which the movement of the object is detected, in an alignment of the divided areas in the infrared-receiving areas.

Infrared sensor device

A temperature detection circuit includes a first voltage source circuit to generate a first voltage having a temperature dependence by utilizing a work function difference of gate electrodes of a plurality of field effect transistors, a second voltage source circuit to generate a reference voltage having no temperature dependence by utilizing a work function difference of gate electrodes of a plurality of field effect transistors, a correction circuit configured to correct the reference voltage and output a corrected voltage, and a subtraction amplifier configured to subtract the corrected voltage from the first voltage, amplify a resulting subtracted voltage, and output a resulting amplified voltage as a correction voltage signal to adjust a temperature coefficient of the correction voltage signal.

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Osaka, Japan

Takeshi Nagahisa