Sharp Kabushiki Kaisha Corporation

Ryosuke Kawashima

Naruichi Yokogawa

Takeshi Nishino

Hiroaki Itoh

Takahiro Inoue

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

When a current mirror circuit is composed of transistors that inevitably form a parasitic photodiode between an epitaxial layer and a substrate layer because of structure of an integrated circuit, a photocurrent increases in proportional to an area of the epitaxial layer. Thus, the area of the epitaxial layer is adjusted in accordance with a current ratio of the current mirror, so as to allow the photocurrent to affect equally on both input and output sides of the current mirror circuit, i.e., so as to cancel the photocurrent. With this, in a current mirror circuit provided in an integrated circuit, it is possible to eliminate the influence of the photocurrent, without considerably increasing an element area or taking special measures to shield light.

Growing community of inventors

Katsuragi, Japan

Ryosuke Kawashima