Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Mitsuya Masuda

Keisuke Yamamoto

Minoru Ueda

Sadahiro Iyehara

Shizuo Inohara

Yukio Uchida

Yoshio Yasumoto

Namio Yamaguchi

Tomoaki Iwamoto

Tomohiro Sakata

A vertical linearity correction circuit including diodes and resistors is provided in a vertical deflection circuit, and a vertical deflection voltage applied to a vertical deflection yoke is corrected so as to follow a change in input impedance of the vertical deflection yoke. As a result, the vertical deflection speed in the vicinity of the central part of the image plane of the color picture tube is prevented from decreasing.

Vertical deflection circuit

A dynamic focus circuit enables ideal focusing characteristics to be obtained across the entire screen of a wide-angled cathode ray tube, by generating a dynamic focus voltage having a flat-bottomed waveform through the addition of a simple circuit to a conventional analog circuit. If an S-shaping voltage method is used, the voltage of a signal induced in a secondary coil of a step-up transformer for raising the voltage of a parabolic waveform signal having a horizontal deflection period switches the gain for converting the parabolic waveform signal to a dynamic focus voltage, according to whether the induced voltage exceeds a specified reference value. If the induced voltage does not exceed the specified reference value, the parabolic waveform signal is converted to the dynamic focus voltage at a gain of less than one. If a DAF (Dynamic Focus) signal generating IC is used, a gain control voltage for controlling a gain of the parabolic waveform signal generated by the DAF signal generating IC is altered so that the gain is smaller than one at the approximate midpoint of a horizontal deflection period, and increases as it moves out to the edges of the screen.

Dynamic focus circuit suitable for use in a wide-angled cathode ray tube

A flat CRT type color image display apparatus comprises a number of horizontally disposed parallel line cathodes, vertical and horizontal deflection means and electron beams control means, wherein a clock pulse signal is produced by frequency-multiplying a pulse signal which is synchronized with color sub-carrier of the color TV signal, chrominance signal is A/D converted using the clock signal, therewith producing a PWM signal with which electron beams are controlled.

Color image display apparatus

The video image display apparatus of flat tube type comprising

Image display apparatus

A flat CRT type image display apparatus comprises a number of horizontally disposed parallel line cathodes and vertical and horizontal deflection means, and electron beams control means, and the deflection means includes digital memory means storing data for deflection signals, address counter means for producing address signal to read out the digital memory means, D/A converters for converting read out data to produce deflection signals and also a microcomputer for setting and adjusting data in the digital memory means.

A flat type color display apparatus includes a phosphor screen and 15 horizontal line cathodes activated in turn from the top one to the bottom one. An electron beam control means and a beam deflection means are provided. Each horizontal line cathode emits a horizontal sheet-shaped electron beam which is vertically deflected in 16 steps, and is divided into 320 rod-shaped electron beams by 320 vertically oblong slits and individually controlled of its intensity by 320 beam-control electrodes. The rod-shaped electron beams are horizontally deflected each selectively impinging R, G and B vertical phosphor stripes in turn. In the operation circuit, R, G and B video signals are sampled and held in R, G and B parts of 320 sample-hold circuits, and stored at one time in 320 memories for respective colors, and time sharingly applied to the respective beam-control electrodes. A color video image is thereby displayed of 240 lines each having 320 picture elements.

A video image display apparatus of the flat tube and multi line cathode type of the present invention includes a phosphor screen, and a predetermined number (e.g. 15) of line cathodes for in-turn emitting a predetermined number of horizontal rows of electron beams. Each row has a second predetermined number (e.g. 320) of rod shaped electron beams for together producing one horizontal line of image on the phosphor screen. A vertical deflection means is provided for vertical deflection of the electron beams in turn at one vertically divided segment corresponding to one of the horizontal rows by means of a vertical deflection signal, e.g. a step wave having a saw-tooth wave envelope. The envelope is adjusted so as to be expanded or compressed or level changed, thereby eliminating any undesirable black horizontal band on the screen due to non-uniformity of electrode construction. A uniform raster is thereby obtainable.

A flat type display apparatus includes an electron beam source for emitting a row of a large number of electron beams, and a phosphor screen having a phosphor layer which emits light in response to impingement by the electron beams. An electron beam convergence means is provided and an electrostatic deflection means for deflecting the electron beams prior to impingement on the phosphor screen. An electron beam controlling means has a number of electron beam controlling electrodes for individually controlling the current of the electron beams to control light emissions from the phosphor screen. A pulse width modulation circuit feeds electron control signals of a constant voltage and pulse-width modulated by video signal information to be displayed. Light emission control without changing converging conditions of electrostatic lenses is thus obtained so that a good linearity between the video signals and the electron beams is obtained.

An automatic local oscillation frequency control apparatus for a television receiver is disclosed, wherein a video intermediate frequency (VIF) signal is applied to an FM discriminator for generating an AFC voltage through a phase shifter comprised of a serial-parallel resonance circuit, and one of the serial resonance frequency and the parallel resonance frequency of the serial-parallel resonance circuit is selected to be a frequency near a picture carrier frequency while the other is selected to be a frequency which is made by subtracting one half of a differential frequency between the picture carrier frequency and a sound carrier frequency from the picture carrier frequency. The present apparatus can attain an automatic frequency control having a wide pull-in range and a wide hold range.

Automatic frequency control apparatus for television receiver

An automatic frequency control device is disclosed wherein the S-shaped waveform character voltage derived by the FM detection of the video intermediate frequency signal is applied to a local oscillator so as to correct its oscillation frequency. The S-shaped waveform character voltage is corrected in response to the output voltage derived by the detection of the sound carrier of the adjacent receiving channel so that the pull-in range may be increased.

Growing community of inventors

Kyoto, Japan

Mitsuya Masuda