Seiko Instruments Inc

Isamu Fujii

Yuji Hishiki

Shinichi Idomukai

Fumiyasu Utsunomiya

Taro Yamasaki

Yoshiaki Saka

Satoshi Machida

Toshihiko Omi

Toshiyuki Uchida

Provided is a proximity sensor using a photosensor, which is easy to use and reduced in power consumption. In the proximity sensor, a first photosensor is used to detect a change in amount of ambient light entering the first photosensor, which is caused when a finger is coming close thereto, and a detection signal is output based on a result of the detection. The photosensor includes, for example, one or a plurality of PN junction elements connected in parallel.

Proximity sensor using photosensor

Provided is a light receiving circuit for detecting a change in amount of light, in which an input circuit at a subsequent stage is compact and inexpensive and current consumption is low. The light receiving circuit includes: a photoelectric conversion element for supplying a current corresponding to an amount of incident light; an N-channel MOS transistor including a drain supplied with the current from the photoelectric conversion element; and a control circuit for controlling a gate voltage of the NMOS transistor via a low pass filter so that a drain voltage of the N-channel MOS transistor becomes a desired voltage. The control circuit outputs a control state output signal, which is a GND terminal voltage when a delay amount of control on the gate voltage of the NMOS transistor performed via the low pass filter is less than a desired delay amount, and is the drain voltage of the NMOS transistor when the delay amount of control on the gate voltage of the NMOS transistor performed via the low pass filter is the desired delay amount or more. The light receiving circuit outputs the control state output signal as an output signal.

Light receiving circuit

An electric charge storage method is used in which a photoelectric current generated in a photodiode is stored for a predetermined time period and the stored electric charge is amplified by an amplifier to obtain an output. Further, the storage time period is switched so that an output from the circuit has a characteristic of a piecewise linear approximation of a logarithm of an illuminance, permitting a sufficient resolution even in darkness.

Photodetection device

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

A low noise and lower power consumption receiver including a CRC error correction circuit which is constructed at low cost, prolongs a life of a battery and enhances a receiving sensitivity. The receiver comprises a data processing unit which continuously determines errors in received data encoded by a CRC code and corrects them by comparing with reference syndrome patterns, a microprocessor circuit including a data RAM connected with local data buses and local address buses and a serial data receiving apparatus including state control means, a synchronizing circuit, an ID comparing circuit and a circuit for gating system clock. The high performance and low power consumption receiver may be realized with less additional circuits, having more flexibility to the increase of services.

Receiver for communication

An IC for communication includes a single oscillating circuit, which is capable of flexibly dealing with the change of data rate or data processing load, and is produced at a low cost and consumes low electric power. In the IC for communication, a frequency multiplying circuit( ) is inserted between the output of an oscillating circuit( ) and a micro-controller circuit( ), or a frequency dividing circuit( ) is inserted between the oscillating circuit( ) and a data receiving circuit( ). A receiving address is stored in a dual port RAM( ). Further, by controlling a receiving frequency of synchronous codes, battery saving efficiency is increased.

Semiconductor integrated circuit for communication and battery saving method for the same

In a selected paging signal type receiving apparatus, a transmission code is received which is arranged by coupling a series of signal codes including a preamble, a sync code, and a message code. Even when signal reception is interrupted, this receiving apparatus can immediately respond to an interference condition and a completion of a signal transmission. In the case of the interference condition, the receiving apparatus can be immediately recovered to the signal reception operation after the interference condition disappears. This selected paging signal type receiving apparatus with a simple arrangement is arranged by a sync signal generator for generating a signal having the same time period as that of the sync code, and reset when the preamble is detected; a receiving circuit intermittently operated in response to the sync signal from a sync signal generator; a sync code detecting circuit and a preamble detecting circuit intermittently operated in response to this sync code; and also a paging code detecting circuit operated only when the sync code is detected.

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Chiba, Japan

Isamu Fujii