Matsushita Electric Works, Ltd.

Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Panasonic Electric Works Co., Ltd.

Teruki Hatatani

Yuji Takada

Suguru Fukui

Shinji Sakamoto

Toshio Fujimura

Hiroshi Matsuda

Takayuki Nishikawa

Takahiro Sono

Atsushi Hironaka

The object detection device includes: a pyroelectric element configured to output a current signal in response to a change in an amount of infrared light; an I/V conversion circuit including an operational amplifier, a capacitive element serving as a feedback circuit, and a discharging circuit, and configured to convert the current signal to a voltage signal; an A/D conversion circuit configured to convert the voltage signal to a first digital signal; a digital filter configured to extract a detection component having a frequency included in a frequency band associated with an object from a waveform represented by the first digital signal by subjecting the first digital signal to an arithmetic processing, and create a second digital signal representing a waveform of the detection component; a judgment circuit configured to detect the target based on the second digital signal; and a control unit configured to control the discharging circuit based on a period corresponding to a predetermined frequency not greater than a lower limit of the frequency band to discharge electric charges stored in the capacitive element.

Object detection device

A current-voltage converting circuit () is provided with a first feedback circuit () and a correcting transistor (Q). The first feedback circuit () outputs, of an output voltage (V), a voltage according to a magnitude of a low-frequency component that is not greater than or equal to a predefined first cut-off frequency. The correcting transistor (Q) extracts a correction current (I) according to a magnitude of an output of the first feedback circuit () from a sensor current (I). The first feedback circuit () has a first integrating circuit () and a sample-and-hold circuit (). The first integrating circuit () integrates the output voltage (V) of a conversion section (). The sample-and-hold circuit () samples and holds an output of the first integrating circuit () during a sensing period at which a pulsed detection signal is inputted. Means for preventing an incidence of ambient light onto a light-receiving section can be simplified or omitted as a result.

Smoke sensor including a current to voltage circuit having a low frequency correction means to produce a correction current

The pyroelectric infrared detection element has a pyroelectric element including opposite first and second electrodes and an infrared absorption part. The first and second electrodes are formed on first and second thickness-direction surfaces of a pyroelectric substrate respectively. The detection element includes an output terminal unit including first and second output terminals on the substrate, and first and second wiring parts connecting the first and second output terminals to the first and second electrodes respectively. The first wiring part includes a connecting line being a conductive layer on the first surface to connect the first output terminal to the first electrode, and a canceling line for canceling charges generated at the connecting line in response to a change in temperature of the substrate. The canceling line is a conductive layer on the second surface to be insulated from the second electrode and to be connected to the connecting line.

Pyroelectric infrared detection element and infrared sensor using the same

A wireless sensor device including a sensor configured to sense a target object and provide a sensor signal of varying levels indicative of condition of the target object, a signal processing circuit configured to amplify the sensor signal and provide an amplified electric analog signal, and a detection circuit configured to receive the amplified analog signal and provide a detection output when the electric analog signal goes beyond a predetermined detection threshold. A radio transmitter transmits a radio detection signal in response to the detection output. A power supply is configured to provide an electric power to the signal processing circuit and the radio transmitter and includes a power generating element which converts an external energy into the electric power to be accumulated in the power supply. A controller activates the radio transmitter only in response to the detection output, permitting the radio transmitter to generate the radio detection signal.

Wireless sensor device

An infrared detecting device for reducing current consumption while maintaining performance is disclosed. The device includes a drive power supply circuit which comprises a current generating circuit and a distribution circuit, and which supplies a drive current to each of signal circuits comprising an I/V conversion circuit, a voltage amplification circuit, a detection circuit and an output circuit. The current generating circuit includes a reference current source, a fixed current source providing a fixed current based on the reference current and a variable current source providing a variable current stepped up or down to any different currents based on the reference current. The distribution circuit distributes the drive current to a part of the signal circuits based on the current from the fixed current source and distributes the drive current to a remaining part of the signal circuits based on the current from the variable current source.

Infrared detecting device

An infrared detecting circuit is provided with a current-to-voltage converting circuit including a capacitor connected with an inverting input terminal and an output terminal of an operational amplifier and a resistance circuit element connected in parallel with the capacitor, an inverting amplifying circuit connected with an output side of the current-to-voltage converting circuit, a band-pass filter circuit connected with an output side of the voltage amplifying circuit, and an output circuit connected with an output side of the band-pass filter circuit. The infrared detecting circuit and an infrared detector including this circuit can be miniaturized.

Infrared detecting circuit and an infrared detector

In an infrared-rays detector, a pyroelectric element detects existence or movement of a human body, and the output signal of the pyroelectric element is converted to a voltage signal. Then, the voltage signal is subjected to waveform analysis. Then, a detection signal is outputted only when a waveform generated by a human body is detected by the waveform analysis. For example, the voltage signal is amplified at two different frequency ranges, and the amplified signals are used for discriminating a signal due to a human body. Then, a noise such as a popcorn noise of the pyroelectric element is prevented to be detected erroneously as generated by a human body.

Infrared-rays detector

A pyroelectric infrared ray sensor is constituted with a current-voltage converting circuit utilizing an impedance of feedback capacity, obtained by adding the feedback capacity to an operational amplifier receiving as an input an element current from a pyroelectric element, whereby the current-voltage converting circuit can be improved in S/N ratio without altering characteristics of the pyroelectric element.

Pyroelectric infrared ray sensor

A pyroelectric infrared ray sensor includes a voltage amplifying circuit provided with a signal amplifying part having a non-inverting amplifier, with an integrating circuit, and with voltage dividing resistors connected at a position where an input V.sub.IN to the voltage amplifying circuit and an output V.sub.B of the integrating circuit are resistance-divided to a non-inverting input terminal of the signal amplifying part which is practically formed by an operating amplifier, wherein the signal amplifying part includes a low-pass filter formed by a resistor and a capacitor, whereby the electrostatic capacity of the required capacitor can be minimized, and the entire circuit can be minimized in size and also in manufacturing costs.

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Osaka, Japan

Teruki Hatatani