Hitachi, Ltd.

Renesas Electronics Corporation

Renesas Technology Corp.

Michitaka Osawa

Hitoshi Maekawa

Kunio Ando

Makoto Onozawa

Takamitsu Kanazawa

Hiroyuki Miyajima

Koji Kito

Kouji Kitou

Yuji Sano

Soichi Sakurai

Yuichiro Kimura

Syuzo Matsumoto

Hiroki Oguro

Etuo Funada

Yuichirou Kimura

Masahide Kawai

A first semiconductor element having a junction electrode to be connected to a first node of a bidirectional switch circuit is mounted on a first metal base plate to be a heat dissipation plate, and a second semiconductor element having a junction electrode to be connected to a second node of the bidirectional switch circuit is mounted on a second metal base plate to be a heat dissipation plate. The junction electrode of the first semiconductor element has the same potential as that of the first metal base plate, and the junction electrode of the second semiconductor element has the same potential as that of the second metal base plate. Also, the respective metal base plates and non-junction electrodes of the respective semiconductor elements are connected by metal thin wires, respectively, thereby configuring the bidirectional switch circuit.

Bidirectional switch module

Subcoils are provided on the core portion that serves as a deflection yoke, and a current for correcting convergence is supplied to the subcoils to correct convergence. Further, means is provided to suppress harmful current that is produced by mutual induction between the subcoils and the deflection coils, and whereby the deflection of electron beam and the correction of convergence are effected independently of each other.

Electron beam deflector

A horizontal deflection high-voltage circuit using the diode modulation horizontal deflection circuit is provided with a means detecting the high voltage output from the flyback transformer for supplying the input terminal of the flyback transformer with a control signal which controls the high voltage to be kept constant and a means detecting a variation in the control signal for supplying one end of a modulation coil with a control signal which controls the horizontal deflection current to be kept constant, whereby a horizontal deflection high-voltage circuit practically free from irregularity of adjustment and deterioration due to aging is provided.

Horizontal deflection high-voltage circuit

A differential amplifier circuit including not only first and second transistors whose emitters are coupled together through a resistor to form a differential transistor pair, but also first and second distortion-correcting transistors, is disclosed. In this circuit, the base terminal of the first transistor is connected to the emitter terminal of the first distortion-correcting transistor, the base terminal of the second transistor is connected to the emitter terminal of the second distortion-correcting transistor, the emitter terminals of the first and second distortion-correcting transistors are connected to a current source of the current control type, and a ratio of the current flowing through the first distortion-correcting transistor to the current flowing through the second distortion-correcting transistor is made equal to a ratio of the emitter current of the second transistor to the emitter current of the first transistor, to cancel the non-linear distortion due to the base-to-emitter voltages of the first and second transistors by the non-linear distortion due to the base-to-emitter voltages of the first and second distortion-correcting transistors, thereby eliminating non-linear distortion from the output of the differential amplifier circuit.

Differential amplifier circuit

A blanking pulse generation circuit for generating a blanking pulse with a large duration is disclosed. The blanking pulse generation circuit includes a flyback pulse shaping circuit for shaping a flyback pulse and generating a rectangular wave signal and a front pulse generation circuit for adding a front pulse to the front edge of the rectangular wave signal. The blanking pulse is formed by the blanking pulse generation circuit for adding a front pulse to the rectangular wave signal.

Horizontal blanking pulse generation circuit used for display unit with

A capacitor is provided between an amplifier whose output impedance is relatively high and a cathode of a cathode ray tube. A transistor is also provided having an emitter-collector path connected in parallel with said capacitor and a base electrode which is connected to a D.C. voltage source through a switch which is turned on during a horizontal retrace period and off during a horizontal scan period. A D.C. restoring operation is achieved by causing almost all of the discharge current of the capacitor to flow through the emitter-collector path, resulting in less discharge current flow through the output impedance of the amplifier.

Clamp circuit for a video signal processor

A horizontal deflection output circuit, such as used in a TV receiver or a display device, includes a series circuit composed of a ringing preventing resistor and a one-way switching element connected in parallel with a linearity correcting coil. That one-way switching element is turned on at the beginning of a horizontal scanning period to feed a current to the ringing preventing resistor but is turned off in the vicinity of a fly-back period to block the flow of the current to the ringing preventing resistor. Thus, the power loss due to the current flowing through the ringing preventing resistor for the fly-back period can be reduced according to the present invention.

Horizontal deflection output circuit

A brightness control circuit for a color display tube comprises voltage regulating means for varying a voltage between an input terminal and an output terminal thereof in dependence on an externally supplied voltage control signal are provided between cathodes of a color display tube corresponding to primary color signals and an output end of the color display tube drive circuit for supplying drive currents to the individual cathodes of the color display tube, and voltage control signal generating means connected to the voltage regulating means for supplying the voltage control or adjusting signals to the voltage regulating means. The voltage control signal generating means include two regulating means, i.e. first regulating means for changing simultaneously all the voltage control signals supplied to the voltage regulating means corresponding to the primary color signals and second regulating means for varying individually the voltage control signals for each of the color signals. Adjustment of cut-off voltage of the color display tube and adjustment of the white balance in the state of high brightness are performed by the second regulating means while the brightness of a raster scanned on the face plate is adjusted with the aid of the first regulating means.

Brightness control circuit for display apparatus with color picture tube

A drive circuit having a transformer with its secondary winding connected to the base of a transistor and its primary winding connected to a drive source by which the transistor is driven to switch, wherein a directional element is connected between a tap provided on the secondary winding and one end of the secondary winding so as to select the ratio between the forward base current and reverse base current of the transistor.

Drive circuit for driving a transistor

A cascode amplifier comprises a grounded-emitter drive transistor which has a collector supplied with a bias current from a bias current source and operates in response to an input signal and a grounded-base (or grounded-gate) output transistor which has a collector supplied with a bias current from a constant voltage source, wherein the collector of the drive transistor is connected to the emitter (or source) of the output transistor. A constant current circuit is connected to the junction between the collector of the drive transistor and the emitter (or source) of the output transistor for supplying a part of the bias current applied to the drive transistor to thereby decrease the bias current of the output transistor while causing the drive transistor to be operated in the linear region. The cascode amplifier is thus imparted with a broad band frequency characteristic.

Cascode amplifier with an improved biasing arrangement

An amplitude-adjusting circuit used for a contrast-adjusting circuit of resistor division type in which a video signal is applied across a pair of series-connected resistors and an output is produced from the junction point of the two resistors. At least one of the resistors is used as a variable resistor. The amplitude-adjusting circuit comprises a current source for supplying a constant current steadily between the terminals of the variable resistor, a high-gain amplifier for controlling the resistance value of the variable resistor, and a filter for separating the video signal component from the change of the value of the variable resistor represented by a voltage change, and introducing the resistance change to the high-gain differential amplifier.

Amplitude adjusting equipment in a signal translation line

Disclosed is a wide band high output amplifier in which a field effect transistor is used as an output element, in which a constant resistance circuit is inserted between the drain terminal of the field effect transistor and a load capacitance such that the impedance characteristic is a constant resistive value and provides a peaking function across the load capacitance so as to improve the high frequency characteristic of the amplifier without increasing the imput impedance of the field effect transistor.

Wide band high output amplifier using a power field effect transistor as

A gamma correction circuit is provided with a first circuit including a first linear element and a first non-linear element connected in series in the above order and a second circuit including a second non-linear element and a second linear element connected in series in the above order. A first connection point is located between the first linear element and the second non-linear element and a second connection point is located between the first non-linear element and the second linear element. A current source for converting a video signal voltage into a current output is connected to the second connection point. Two common collector (or common drain) transistors have their collectors (or their drains) connected to a power supply line. The input terminals of these transistors are connected to the connection point between the first linear element and the first non-linear element and to the connection point between the second non-linear element and the second linear element respectively, and the output terminals are connected to each other through a resistor. In order to decrease the junction capacitance of the transistors as the video signal voltage level increases, a voltage regulator circuit is connected between the power supply line and the first connection point.

Gamma correction circuit

A horizontal deflection circuit comprises a horizontal oscillator circuit, a drive transistor, a horizontal output transistor driven by the output of the drive transistor, a timing circuit for setting a timing delayed by about one fourth the horizontal scanning period from the terminating point of the flyback pulse generated at the collector of the horizontal output transistor, a phase difference detector circuit for detecting the phase difference between the leading edge of the collector pulse of the horizontal drive transistor and the timing set by the timing circuit, and a pulse duration variable output circuit triggered by the output of the horizontal oscillator circuit and with the output pulse duration thereof controlled by the output of the phase difference detector circuit. The horizontal drive transistor is driven by the output of the pulse duration variable output circuit, so that the leading edge of the collector pulse of the horizontal drive transistor is rendered to coincide with the timing set by the timing circuit.

Growing community of inventors

Fujisawa, Japan

Michitaka Osawa