Sharp Kabushiki Kaisha Corporation

Tetsuhide Okahashi

Makio Nakamura

Hiroshi Atarashi

Takao Imai

Masanori Wakiyama

A satellite antenna switching apparatus has LNB ports to which LNBs are connected, receiver ports to which receivers that exchange signals with the LNBs are connected, cascade ports to which another switching apparatus is cascade-connected, and impedance circuits that function as means for detecting the signals exchanged between the LNBs and receivers. The impedance circuits provide impedances according to the connection states of the cascade ports, and are electrically disconnected from the signal paths when another switching apparatus is cascade-connected to the cascade ports. With this configuration, the satellite antenna switching apparatus suffers from less attenuation of the exchanged signals even in a cascade connection of a plurality of stages of switching apparatuses.

Switching apparatus and satellite antenna switching apparatus

Coil(s)and coil(s)of LC resonant circuit(s) are oriented such that their centers are mutually perpendicular. For example, coilmight be mounted so as to stand upright on printed wiring board, and coilmight be mounted so as to lie flush against printed wiring board. Such configuration permitting lines of magnetic force from coiland coilto be oriented so as to be mutually perpendicular, lines of magnetic force from coiland coildo not merge, and coiland coilare not electromagnetically coupled. Accordingly, inductances of respective coilsare unchanged; impedance frequency characteristics of respective LC resonant circuits are maintained at what they should be; and resonant impedance(s) is/are not lowered.

Circuit device

A high impedance circuit of the present invention includes an LC parallel resonance circuit for raising circuit impedance, and a diode, which is connected in parallel to the LC parallel resonance circuit, causing a loop current to flow back via the diode and an inductor in the LC parallel resonance circuit so that a counter electromotive force, due to a surge voltage, which occurs across the inductor is cancelled. A low noise block downconverter which includes a high impedance circuit having a high impedance prevents peripheral circuits from being destroyed by a counter electromotive force, due to a surge voltage, which occurs across the inductor. For this, a diode is provided to cause a loop current to flow back via the diode and the inductor so that the counter electromotive force is cancelled. This makes it possible to cancel the counter electromotive force, to lower the voltage across the inductor to a forward voltage of the diode, and to prevent the destruction of the peripheral circuits such as the high impedance circuit.

High impedance circuit

The present invention is a low noise blockdown converter (LNB) capable of ensuring sharing of specific information between or among a plurality of microcomputers. In the event that receiveris connected to I/O portassigned to slave microcomputerslave microcomputermay receive inquiry or inquiries from receiverfor information specific to LNBUpon receiving such inquiry or inquiries, slave microcomputermay, by way of busrequest that master microcomputerprovide specific information. Upon receiving such request or requests, master microcomputermay, by way of busprovide slave microcomputerwith specific information stored in advance at master microcomputerSlave microcomputermay send this specific information from I/O portto receiver

Low noise blockdown converter

The pin pitches on the respective edges of a plurality of selectively mounted semiconductor devices match one another, and the distances between the edges differ from one another. Shared lands are arranged so as to correspond to contact pins disposed on one edge of the respective semiconductor devices. Accordingly, selectively mounting a plurality of types of semiconductor devices onto a printed circuit board is achieved while saving space.

Land pattern configuration

An LNB (low noise block down converter) that can have a plurality of receivers connected includes a conversion unit receiving a plurality of types of polarized wave signals transmitted from each of a plurality of satellites to convert the plurality of polarized wave signals into a plurality of intermediate frequency signals, an amplify switch connected to the conversion unit to receive the plurality of intermediate frequency signals as inputs, and having a plurality of outputs connected to a plurality of output ports, respectively, determining a status according to a select signal and providing an amplified intermediate frequency signal, and a first control unit receiving digital serial data to select a satellite from an external source via an output port and providing a select signal according to the digital serial data.

Growing community of inventors

Kashihara, Japan

Tetsuhide Okahashi