Sony Corporation

Takahiko Tamura

Jun Ueshima

Hiroshi Murayama

Masaharu Tokuhara

Akira Shirahama

Shinichirou Miyazaki

Yumiko Mito

Hiroyuki Suzuki

Satoshi Miura

Masayuki Hongu

Kyoichi Murakami

Takatomo Nagamine

Yoshinari Sengoku

When an A/D-converted composite video signal is directly outputted while a system clock frequency is switched so as to execute the determination of a signal system, a digital chroma demodulation system prevents the images displayed by the composite video signals from being distorted in accordance with a switching of the frequency of a system clock. The frequency m (=fsc&#xd7;n) of the system clock is synchronized with a color burst signal and is set to fall in a predetermined range by changing a coefficient n in accordance with the system color burst signal freguency. Thus, since a composite video signal is A/D-converted in accordance with a substantially constant sampling frequency, the sampling condition such as a sampling frequency and a sampling point is not greatly changed.

Video signal processing circuit and video signal processing method

In a CRT display and a television set having the same, horizontal/vertical synchronizing signals are separated from a video synchronizing signal in a synchronizing separation circuit, and position information S of a vertical frame is generated on the basis of the horizontal/vertical synchronizing signals in a count-down processor and then converted to corrected vertical frame information W in a function circuit to output a vertical deflection waveform signal and a horizontal deflection correcting waveform signal. Further, the corrected vertical frame information W is compared with predetermined voltages in comparators to detect an effective frame range in the vertical direction.

Cathode ray tube display and television set having the same

A dark level restoring circuit for a television receiver which receives a video signal, clamps a pedestal portion of the video signal to a reference pedestal level by a pedestal clamper, compares the output of the pedestal clamper with a reference dark level, and amplifies the compared result by a gain control amplifier. The output of the pedestal clamper and the amplified compared result are synthesized, the dark peak level is held, and the held dark peak level and the reference pedestal level are compared wherein the gain of the gain control amplifier is controlled by the compared result. A blanking signal is received, and a mute signal is generated which corresponds to a non-video signal portion when the effective raster size of the video signal is smaller than the size of a face plate of a cathode ray tube to which the video signal is supplied. The blanking signal and the mute signal are synthesized and a control signal is generated which controls the gain control amplifier such that its gain is minimized and the holding of the dark peak level is inactive.

Dark level restoring circuit for television receiver

A display device comprising a CRT having a reduced number of components for automatic cutoff adjustment. The device needs an IC having a less number of connection pins. The device adds reference pulses to given portions within every field of video signals. The resulting cathode currents are converted into voltage pulses. These voltage pulses are compared with a reference voltage by a comparator. The output signal from this comparator is counted by forward-backward counters for three primary colors, respectively, and converted into analog form. Level shift circuits for the three primary colors, respectively, control the DC components of the video signals according to the output signals from the D/A converters. In this way, the cutoff characteristics of the CRT are controlled.

Display device

A vertical synchronization processing circuit includes a counter for counting a clock signal synchronized with a horizontal sync. signal, a circuit for resetting the counter in response to a vertical synchronization signal within a predetermined limit prohibiting reset due to a non-standard signal, a memory for storing the data counted at the timing of reset, and a circuit for changing a predetermined limit prohibiting reset due to a non-standard signal according to the data from the memory. A circuit for discriminating an existence of a vertical synchronization interval can also be provided along with a second resetting circuit for resetting the counter if the discriminating circuit detects the existence of the vertical synchronization interval when the counter counts a predetermined number of clock signals in case there is not a vertical synchronization pulse within the predetermined limit.

Vertical synchronization processing circuit

A correction signal generating circuit for a television receiver includes a counter for counting a pulse synchronized with a horizontal sync signal, a memory for storing correction data and a coefficient, and a unit for multiplying and adding contents of the counter and the memory. A signal feedback loop supplies an output from the multiplying and adding unit to an input thereof, and a control unit controls operation of the memory and the multiplying and adding unit, thereby generating a correction signal.

Apparatus for generating television raster distortion correction signals

A parabolic wave generator in a color television receiver or the like wherein, when the amplitude level of an input sawtooth wave is higher than the center level thereof, squared currents of mutually reverse polarities obtained by squaring the difference current proportional to the difference voltage between the two levels are added to each other at a predetermined rate, so that one side portion of a nonsymmetrical parabolic wave is produced. Meanwhile, when the amplitude level of the input sawtooth wave is lower than the center level thereof, squared currents of mutually reverse polarities obtained by squaring the difference current proportional to the difference voltage between the two levels are added to each other at another predetermined rate to thereby produce the other portion of the parabolic wave. Consequently it becomes possible to generate the two side portions of mutually different waveforms. And a desired nonsymmetrical parabolic wave can be achieved by combining such two side portions with each other through addition of the currents thereof without raising any problem in regard of the discontinuity or level difference that may otherwise be caused in the vicinity of the peak of the parabolic wave.

Parabolic wave generator

Oscillation circuit that generates an oscillating signal by charging and discharging a capacitor between two reference voltages employs several constant current sources, with the number of constant current sources that are connected to the capacitor at any one time being controlled so that the oscillation frequency can be changed in a step-wise fashion, whereby the circuitry is relatively simplified compared with known step-wise changing oscillators.

Multifrequency oscillator circuit

A color picture tube for displaying a color picture which has a signal supply that includes a plurality of primary color signal channels for supplying a plurality of primary color signals to the color picture tube and current detecting means connected to the signal supply so as to detect currents flowing through the color picture tube and an automatic white balance circuit for controlling the signal supply in response to the detected currents detected by the current detecting means including a power responsive circuit for generating a control signal when a power switch for the television receiver is turned on and a gate pulse generator which blanks except during reference signal insertion connected to the signal supply to inhibit the supply of primary color signals to the picture display means and first circuit means connected to the power responsive circuit to actuate the gate pulse generator when the power switch is turned on and second circuit means connected to the current detecting means for deactuating the gate pulse generator after the current which flows through the display tube exceeds a predetermined value.

Circuit for blanking the video of a television set for a time after

A dark signal component below a predetermined level of a video signal is varied such that a dark peak level is made to coincide with a pedestal level by feedback control. According to this configuration, a signal component toward a white level side above the predetermined level is not changed by dark restoration, thus obtaining stable color reproduction and stable brightness which are not affected by the dark restoring operation.

Dark level restoring circuit

A CRT drive control circuit for automatically limiting beam current when it is too large. A brightness reduction control and a contrast reduction control are alternately applied in accordance with a dark level detection of a video signal.

Growing community of inventors

Tokyo, Japan

Takahiko Tamura