Abstract: The present invention is directed to a shielding device of a double-sided printed substrate used in a circuit for processing a high frequency signal such as a television tuner circuit and the like, which is arranged such that a first grounding conductor film (12a) is formed on one side of the substrate (11), a second grounding conductor film (12b) is formed on the other side of the substrate (11), both the conductor films (12a, 12b) are connected by a through-hole conductor (15b), an opening portion of a through hole (15a) at at least one side is covered and closed by a solder resist (16), and the shielding plate (13) is mounted on the conductor film (12a) on the one side and both members are soldered. In particular, when a ceramic substrate is used as the substrate (11), it is arranged so as to obtain reliable soldering and satisfactory shielding effects while ensuring the strength thereof.

Abstract: Disclosed is a local oscillator using a dielectric coaxial resonator (27), which is availably used as a fixed local oscillator in double-spot tuners and CATV converters, and which is arranged so that an AFC voltage is applied to a variable-capacitance diode (23) from an output terminal (E) of a frequency control circuit through a first resistor (35), the variable-capacitance diode having its one end being connected to a center conductor of a dielectric coaxial resonator (27) through a capacitor (25) and its other end being AC grounded, and that a first reference potential (V.sub.A) lower than a source voltage (V.sub.CC) by a predetermined value is given to the variable-capacitance diode (23), the one end of the variable-capacitance diode (23) being connected to the source voltage (V.sub.

Abstract: A channel selection apparatus having a double superhet tuner section (15) for converting one of a plurality of television channels contained in an input signal to a fixedly predetermined channel, includes an AFC circuit (11) for producing a frequency control voltage to execute closed-loop frequency control of the second local oscillator (5) of the tuner section while an AFC switch (16) is set in a first condition, whereas when the AFC switch is set in a second condition, a fixed frequency control voltage is applied to the second local oscillator and the frequency control voltage is applied to adjust the oscillation frequency of the first local oscillator (2) of the tuner section such as to compensate for any offset in the transmission frequency of a currently selected channel.

Abstract: An absolute displacement detector utilizing two sensors and a code bearing track having domains arranged such that relative movement between the sensors and the track produces two signals in phase quadrature which are processed with digital circuitry to provide displacement data indicated by a multiple bit digital word whose higher bits indicate number of domains passed and whose lower bits indicate position within a domain.

Abstract: A high frequency amplifier circuit based on an amplifying transistor, e.g. a dual-gate FET, having an A.G.C. voltage applied to a control terminal thereof to control the transistor DC operating current, has a diode connected between an input electrode of the transistor and a source of an input high frequency signal. All or part of the DC operating current of the transistor is passed through the diode as the operating current of the diode to thereby produce a high degree of attenuation by the diode when the transistor current level is small, so that reduced cross modulation interference is produced by the transistor when a high degree of gain reduction is executed by A.G.C. control.

Abstract: The local oscillation circuit in accordance with the present invention is characterized as follows. The collector of an oscillation transistor is grounded for atlernating current. A series resonance circuit consisting of a variable capacitance diode and a resonator is connected to the base of the oscillation transistor. The other end of the series resonance circuit is grounded for alternating current. The emitter of the oscillation transistor is connected to the collector of an amplifying transistor. The emitter is grounded through a capacitor that removes or reduces the a.c. component and passes the d.c. component. An oscillation signal taken from the emitter of the oscillation transistor is fed to the base of the amplifier transistor. A local oscillation output signal is taken from the collector of the amplifier transistor, and bias potential to the amplifier transistor is impressed from the power source to the base of the amplifier transistor.

Abstract: On an upper surface of a substrate (20) a band-pass filter (29) is provided, and on the opposite (lower) surface of a substrate (20) a low-pass filter comprising a conductive layer pattern (27) and capacitors (22,23) is provided, wherein a conductive layers (27) are provided on substantially the entire area of the upper surface excluding portions for terminals and on the lower surface excluding portions for the low-pass filter and the terminals, and by connecting both conductive layers by means of a row of through-hole connections, the input terminal (24) and the output terminal (25) are shielded from each other.

Abstract: In an amplifier for a high frequency signal used to amplify a signal having a high frequency in a television tuner, a receiver for satellite broadcasting, and the like, at least two stages of dc-coupled grounded-emitter type amplifiers (Q.sub.1, Q.sub.2) are configured in an integrated circuit, a resistor (R.sub.13) is connected between an emitter of the grounded-emitter amplifier (Q.sub.2) in the second stage and the grounding, a terminal for connecting an external device is disposed to be connected via a bonding wire to the emitter of the grounded-emitter amplifier (Q.sub.2) in the second stage, and a filter circuit (11) including an inductance of the bonding wire and developing a low impedance for a particular frequency is disposed between the terminal and the external grounding.

Abstract: The present invention relates to a local oscillation apparatus which is used as a local oscillator of a communication apparatus or as a fixed local oscillator of a tuner. The present invention comprises a coaxial resonator (1) and an amplifying circuit (26) having an output end connected to a central conductive member of the coaxial resonator (1) through a first capacitor (2), an input end connected to the central conductive member through a second capacitor (3), and a variable capacitance diode (5) having one end connected to the central conductive member of the coaxial resonator (1) through a third capacitor (4) and the other end grounded so as to permit an alternating current only to be flowed.

Abstract: A magnetic head having a pair of core halves each combined through a magnetic gap, each of the core halves comprising a core base having slanted side surfaces on the side opposing to the magnetic gap and a magnetic thin layer formed on the surfaces of the core base on the side opposing the magnetic gap with magnetic material of high saturation magnetic flux density, the minimum value of the sum of products of vertical cross sectional areas of the respective magnetic paths of each of the core halves except for the path of the magnetic gap and the respective saturation magnetic flux densities of the respective parts is greater than the product of the area of the magnetic gap and the saturation magnetic flux density of the magnetic thin layer.

Abstract: A data transmission system comprises a transmitter and a plurality of serially connected receivers. The transmitter, when energized, outputs an initialization signal to all of the receivers and also outputs a data of a predetermined value to the first receiver. In response to the initialization signal, the first receiver stores the received data in a register and modifies the received data to output a modified data to the second receiver. The second to last receivers operate in the same manner, so that different data are stored in the respective registers of the receivers. To transmit a given data to a selected one of the receivers, the transmitter outputs the given data with an identification code equal to the data stored in the register of the selected receiver. Although each of the receivers compares the received identification code with the contents of the register, only the selected receiver outputs a coincidence signal and stores the received data into a data utilization circuit thereof.

Abstract: A high output light emitting diode (LED) includes an active layer of GaAsP and a window layer formed of either InGaP or InGaAsP. An LED having this structure has an enhanced optical output, and can be manufactured easily and at low cost.

Abstract: A frequency conversion apparatus for converting a high frequency signal into an intermediate frequency signal includes a mixer section for mixing a high frequency signal with a local oscillator signal so as to obtain an intermediate frequency signal, and an amplifier connected to the mixer section via a high frequency stopping circuit for supplying a constant direct current to the mixer section as a constant current source. A current flowing in the mixer section when the local oscillator signal is applied is kept substantially equal to a direct current flowing in the mixer section when no local oscillator signal is applied thereto. The amplifier is used for amplifying either the high frequency signal or the intermediate frequency signal, or both signals at the same time.

Abstract: A composite stretched film having one surface adhesive, while the other nonadhesive is wrapped spirally or helically about an article to be packed to form first and second superposed layers. After forming a first layer, the composite film is inverted so that the first and second layers are bonded together with their adhesive surfaces, while the nonadhesive surface of the first layer is brought to contact with the article and the nonadhesive surface of the second layer is faced outward.

Abstract: The video IF signal is applied to a carrier amplifier so that the signal is amplified and limited in amplitude and consequently only the carrier can be derived. The video IF signal is also amplified by a linear amplifier and compensated by a phase compensation circuit in such a way that the relative phase difference between the outputs from the carrier amplifier and linear amplifier can be eliminated. The outputs from the carrier amplifier and linear amplifier are applied to a synchronous detector, whereby the television video signal without any distortion can be derived.