Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Hisakazu Hitomi

Takashi Koga

Hideyuki Naka

The luminance signal-color signal separating circuit obtains signals of three lines by a 1H delaying circuit. Further, by unit delaying circuits, signals at three points are obtained in each line. Thus, signals at nine points continued vertically and horizontally are input into a color signal detecting circuit which determines an oblique correlation of the signals at these nine points to thereby obtain the degree of the color. The color signal detecting circuit obtains a color signal output having had the oblique luminance component removed by the operation of the color signal component from a three-line color separating circuit and the degree of the color.

Luminance signal and chrominance signal separating circuit

A filter circuit for filtering an input signal including a DC component signal with a prescribed DC level and an AC component signal. The filter circuit includes a time constant circuit for imparting the input signal with prescribed frequency characteristics, the time constant circuit including a variable impedance device and a capacitor, and a control signal source for supplying a control signal for adjusting the impedance of the variable impedance device, the control signal source including a DC source for generating a DC control signal and a compensation source for generating a compensation signal equivalent to the AC component signal of the input signal.

Filter circuit

An automatic adjustment circuit for adjusting the time constant of a filter circuit, which receives a reference signal having a predetermined voltage and a clock signal. The adjustment circuit includes an integration circuit for generating an integrated signal having a variable voltage level with periodic peak values, which includes a controllable current generating circuit, a capacitor coupled for charging a current from the controllable current generating circuit and a switch for alternately charging and discharging the capacitor in response to the clock signal, a comparator for comparing the peak value with the reference voltage and generating a control signal for adjusting the time constant of the filter circuit and a feedback circuit coupled between the comparator and the controllable current generating circuit for automatically controlling the control signal.

Time constant automatic adjustment circuit for a filter circuit

An emitter-coupled astable multivibrator capable of reducing a temperature drift of an oscillation frequency to zero is disclosed. The multivibrator includes first and second transistors, the emitters and collectors of which are cross-coupled, and which are turned ON and OFF at given intervals in accordance with the control current; a capacitor, connected between the emitters of the first and second transistors, to be charged and discharged, the charging polarity of the capacitor being alternately inverted upon the turning ON/OFF of the first and second transistors; third and fourth transistors, the bases of which are commonly connected to a power source circuit, and the emitters of which are respectively connected to the collectors of the first and second transistors; and a fifth transistor, the base of which is connected to the power source circuit to have a predetermined potential difference from the base potentials of the third and fourth transistors, and the emitter of which is connected to the collectors of the first and second transistors through first and second resistors, respectively. The emitter current density of the fifth transistor is different from that of the third or fourth transistor to compensate for the temperature drift.

Current-controlled multivibrator with temperature compensation

A resistor, together with a charging capacitor, is connected in series between the emitters of transistors to constitute an emitter-coupled astable multivibrator to be used with a voltage-controlled oscillator. The resistance of the resistor is given by:

Voltage-controlled oscillator of emitter-coupled astable multivibrator

A current mirror circuit capable of accurately setting the ratio between input current and output current. The circuit includes a plurality of input terminals and a plurality of output terminals. A plurality of transistor pairs is provided with the first transistor of each pair having its collector connected to an input terminal. In addition, the collector of each first transistor in each pair is coupled to its own base. The bases of the transistors in each pair are coupled together, while the collector of the second transistor in each pair is coupled to an output terminal. The transistors connected to input terminals have their emitters coupled together and grounded through a first resistor. The transistors coupled to output terminals have their emitters coupled together and are grounded through a second resistor. Such a circuit allows ratios between input and output current to be set very accurately.

Current mirror circuit

A temperature-compensating bias circuit for biasing a transistor circuit such as a multivibrator is disclosed. In the bias circuit, a series circuit formed of a first resistor and a parallel circuit consisting of a first circuit includes a second resistor and n diodes and a second circuit which includes a third resistor and m diodes, is connected between a power source line and a ground line. A voltage generated from a bias output terminal for driving the multivibrator has the effect of cancelling temperature drift of the multivibrator, and includes temperature drift represented by a temperature coefficient which varies according to the number of diodes in the first and second circuits.

Growing community of inventors

Yokohama, Japan

Hisakazu Hitomi