Sharp Kabushiki Kaisha Corporation

Takeshi Nishino

Naruichi Yokogawa

Takahiro Inoue

Hiroaki Itoh

Ryosuke Kawashima

Norikatsu Koide

Kazuo Noda

Akio Aioi

In an optical communication-use receiving circuit of the present invention, the pulse width of the received pulse which is a binary signal corresponding to the signal optical pulse is specified by using an integration circuit and a trigger generating circuit. If the pulse width of the received pulse is not shorter than a predetermined value, a signal having a fixed pulse width is outputted as an output signal from a one-shot pulse generating circuit, so that a pulse having a constant pulse width corresponding to the specified communication speed is outputted. Accordingly, if the pulse width deriving from the signal optical pulse is larger than a certain value, the communication is deemed as a low-speed communication, and a pulse having a constant pulse width corresponding to the communication speed is outputted. As a result, it is possible to realize a small-size receiving circuit and a small-size electronic device which require no external switching-over terminal.

Receiving circuit and electronic apparatus for optical communication

A receiving circuit stops a one shot timer from generating an output signal immediately after the output signal is outputted to an external entity until a predetermined stretch time elapses. With this arrangement, the receiving circuit will not generate a new output signal even if (i) noises generated by a voltage fluctuation of the output signal appear on an amplified signal immediately after the output signal is outputted (at the end of the output), and (ii) the value of the amplified signal exceeds a threshold value. Therefore, the receiving circuit can make sure that an unnecessary output signal will not be generated due to the noises.

Infrared radiation receiving circuit, electronic device, and infrared radiation receiving method

An infrared transmitter circuit causes an output current to flow to a light emission diode via a current mirror circuit constituted of three transistors by using a current supplied from a power source circuit, so that the light emission diode emits light. When a voltage Vvaried by charging a capacitor with a current flowing from the power source circuit exceeds a reference voltage (voltage V), an output of a comparator resets a D flip-flop, so that an output of the D flip-flop varies to '0'. Thus, an output of a NAND gate to which that output and a transmission signal are inputted causes a transistor (N-channel FET) to turn ON so as to stop operation of the current mirror circuit, and causes a transistor (P-channel FET) to turn OFF so as to cut a connection between the power source circuit and a power source line. Thus, it is possible to reduce power consumption in operation of a protection circuit which stops supplying the output current to the light emission diode.

Infrared transmitter circuit and electronic device

A carrier detection circuit of the present invention detects groups of pulses having a carrier frequency by using a detector, and integrates, by an integrator, a time in which the groups are detected, so as to generate a carrier detection level. Therefore, a transistor is only requested to have responsibility with respect to a frequency of a base band component, but not to the carrier frequency. This ensures a margin with respect to a response of the transistor, while allowing a feeble current to be used as charging and discharging currents for the capacitor. In this way, even if a capacitor in use has such a small capacity that the capacitor can be incorporated in an integrated circuit, the detection of the carrier is performed accurately. Meanwhile, by further providing a level change-over circuit, which increases an output of the detector relative to a reference integral value during a time in which the carrier is detected, it is possible to reduce malfunction caused by a light noise having swelling, in case an infrared ray remote control is used.

Carrier detection circuit and infrared ray remote control receiver

The semiconductor light emitting device has a gallium nitride base compound semiconductor layer expressed by a general formula of In Ga Al N (x&plus;y&plus;z&equals;1, 0&lE;x&lE;1, 0&lE;y&lE;1, 0&lE;z&lE;1). A second intermediate layer is provided between a GaN layer and a light emitting layer, and the second intermediate layer has a lattice constant closer to that of the light emitting layer than that of the GaN layer. As such, when a substrate such as Si substrate having a smaller coefficient of thermal expansion than the nitride semiconductor film is employed, occurrence of cracks is prevented and good crystallinity of the nitride semiconductor film is assured, and accordingly, a long-life and high-luminance nitride base semiconductor light emitting device is obtained.

Semiconductor light emitting device having gallium nitride based compound semiconductor layer

The present invention has an object to control easily the pulse width of an output by operating a limiting circuit appropriately even if the power voltage is low. A limiting circuit is provided on the input side of a hysteresis comparator circuit to prevent saturation. A limit voltage Vlimit is set by a bias circuit so as to change in accordance with the operation of the hysteresis comparator circuit. When an input voltage Vsig exceeds a hysteresis threshold voltage Vth, the limit voltage Vlimit is dropped in response to a drop of the hysteresis threshold voltage Vth. Thus, the width of the pulse width can be controlled while maintaining the condition that the limit voltage Vlimit is higher than the hysteresis threshold voltage Vth.

Comparator circuit and infrared signal receiving apparatus

A charge/discharge circuit creates a carrier detection level based on a received signal in a carrier detector circuit for detecting the presence or absence of a carrier in such applications as a receiver for an IR remote controller. The charge/discharge circuit operates to amplify a current, that is produced in n-type transistors QN , QN , QN and a reference current source, in a p-type transistor QP . The amplified current is mirrored by a current mirror circuit to be supplied as an emitter current of a p-type transistor QP . The charge/discharge circuit charges a capacitor with a small current, i.e., a base current of the p-type transistor QP . The charge/discharge circuit includes a bias voltage source which produces such a bias voltage that the emitter-collector voltage of the p-type transistor QP becomes substantially equal to the emitter-collector voltage of the p-type transistor QP . As a result, it is possible to limit an error of a charge current charged into the capacitor, which is caused by the emitter-collector voltage dependent change of the collector current and thus the base current, known as the Early effect.

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Nara, Japan

Takeshi Nishino