JPS62274890A - Color television circuit - Google Patents

Abstract

PURPOSE:To shorten the time shifting to a next fluorescent material from the fluorescent material having an electron beam and to improve a color purity by changing the horizontal scanning speed of the electron beam with a frequency three times of a triplet frequency. CONSTITUTION:From a frequency triplicating circuit 14, a signal having the frequency three times of the frequency of a triplet signal is transmitted to a phase amplitude adjusting circuit 18, the phase of the signal having the frequency three times of the triplet signal is adjusted by the phase amplitude adjusting circuit 18, the vertical rise part A of a current waveform indicates a scanning time for the intermediate part of the respective fluorescent materials of RGB and a horizontal part B indicates the scanning time of the respective fluorescent materials. Thereby, the scanning of the electron beam is rapidly carried out in the intermediate parts of the respective fluorescent materials, so that the time during which the two fluorescent materials are simultaneously irradiated by the electron beam is shortened, the color purity is improved and a color television of a good picture quality is obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of the Invention The present invention relates to a beam index type color television circuit.

Conventional color televisions use cathode ray tubes of shadow mask type, beam index type, etc. Among these, in the case of the beam index method, in addition to the three primary color RGB phosphors arranged repeatedly in stripes perpendicular to the horizontal scanning direction of the electron beam on the phosphor screen inside the faceplate, UV A phosphor is arranged near the R phosphor, for example (see FIG. 4). When the UV phosphor is irradiated with an electron beam, the UV phosphor emits ultraviolet light, and a UV sensor disposed within the CRT detects the generation of the ultraviolet light and issues a beam index signal. Using this beam index signal, the three primary colors RGB
A color image can be reproduced by controlling the amount of the electron beam using the electron beam that sequentially hits the phosphor and the synchronized and time-divided RGB color reproduction image signal.

Problem to be Solved by the Invention Incidentally, the horizontal scanning described above is performed by applying a sawtooth horizontal deflection current to the deflection coil as shown in FIG. 3, but the increment of this deflection current over time is constant. Therefore, horizontal scanning is performed at a constant speed. Therefore, in the beam index method, when the electron beam moves from one phosphor to the next, both phosphors are irradiated at the same time, resulting in a limit to color purity.

The present invention was made to solve these problems of the conventional beam index method, and its purpose is to provide a color television circuit using the beam index method that can improve color purity. It is about providing.

In order to achieve the above object, the beam index type color television circuit of the present invention includes means for detecting an index signal, and means for processing the index signal to form a triplet. and means for generating a signal having a frequency three times that of the beam index cathode ray tube, and the signal generated by this means is superimposed on the horizontal deflection current or passed through a separate auxiliary coil to generate the electron beam of the beam index type cathode ray tube. It is characterized by varying the horizontal scanning speed.

□In the beam index color television circuit with the above configuration, the horizontal scanning speed of the electron beam can be changed at a frequency three times the triplet frequency.
This makes it possible to shorten the time it takes for the electron beam to move from one phosphor to the next. Therefore, the time for the electron beam controlled by such a circuit to simultaneously irradiate both phosphors is shorter than in the prior art, improving color purity.

Embodiment FIG. 1 is a block diagram of an embodiment of a color television circuit according to the present invention. In this embodiment, as shown in FIG. 4, the R phosphor r, the G phosphor g, and the B phosphor are arranged in order in a direction perpendicular to the horizontal scanning direction indicated by the arrow in the figure, and a beam index signal is generated. This is for a beam index type cathode ray tube arranged near each R phosphor r on a UV phosphor.

In FIG. 1, 1 is a tuner circuit, 2 is a video detection circuit, and 3 is a color reproduction circuit. The RGB color signals sent out from the color reproduction circuit 3 are sent to the addition circuit 7 via switch circuits 4 to 6, respectively, and are sent to a cathode ray tube (hereinafter referred to as CRT).
The drive circuit 8 for 9 is driven. The electron gun 10 is controlled by the output of the drive circuit 8.

A UV sensor 12 disposed within the CRTQ detects ultraviolet light emitted by the UV phosphor and emits a signal. The signal is amplified by an amplifier 13 and input to a circuit 14 that triples the frequency and a comparator 15. As described above, since the UV phosphor is placed between the R phosphor r and the B phosphor, the signal emitted from the UV sensor 12 becomes a triplet signal. The frequency of this I triplet signal (triplet frequency) is output from the frequency triplet circuit 14.
A signal having a frequency three times as high as 1 is sent to the comparator 16 and converted into a binary signal. This binary signal is sent to the ternary counter 17, and the output of the ternary counter 17 controls the switch circuits 4-6.

In this embodiment, the output signal of the frequency tripler 14 is also sent to the phase and amplitude adjustment circuit 18, and the output signal of the phase and amplitude adjustment circuit 18 is sent to the auxiliary deflection yoke 11 via the amplifier 19. It is arranged to be sent to a deflection coil. Therefore, the electron beam emitted from the electron gun 10 is equivalent to being horizontally scanned by a horizontal deflection current having a waveform as shown in FIG.

The waveform of this horizontal deflection current is obtained by superimposing a signal with a frequency three times that of the triplet signal on the sawtooth horizontal deflection current shown in Figure 3, and a portion of it is enlarged within the circle in Figure 2. As shown in the figure, the waveform has a substantially step-like shape, and consists of a portion A that rises approximately vertically and a portion B that is approximately horizontal.

In the vertical rising portion A of the current waveform, the electron beam is rapidly scanned horizontally, while in the horizontal portion B of the current waveform, the electron beam is scanned slowly. Therefore, the phase of the signal having three times the frequency of the replet signal is adjusted by the phase amplitude adjustment circuit 18, so that the vertical rising portion A of the current waveform becomes the scanning time of the intermediate portion of each RGB phosphor. If horizontal part B is set to be the time when each phosphor is scanned, the scanning of the electron beam will be performed rapidly in the middle part of each phosphor, so the electron beam will irradiate two phosphors at the same time. time is reduced.

In the above embodiment, a signal having a frequency three times that of the triplet signal is applied to the coil of the auxiliary deflection yoke. The signal may be applied to the horizontal deflection current to directly superimpose the signal on the horizontal deflection current.

Effects of the Invention As is clear from the second explanation, the color television circuit of the present invention makes it possible to change the horizontal scanning speed of the electron beam.
Since the time for irradiating the individual phosphors simultaneously is reduced, color purity is improved, resulting in a color television with better image quality.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram of the horizontal deflection current according to the present invention, Fig. 3 is a waveform diagram of the conventional horizontal deflection current, and Fig. 4 is a diagram of the waveform of each phosphor. It is an explanatory view showing an example of arrangement typically. 9... Cathode ray tube CRT, 10... Electron gun, 11...
・Auxiliary deflection yoke, 12...UV sensor, 14...
Frequency tripler circuit, 18...phase amplitude circuit. Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] It is equipped with means for detecting an index signal, and means for processing the index signal to generate a signal having a frequency three times the triplet frequency, and superimposing the signal of this generation means on the horizontal deflection current or sending it to a separate auxiliary coil. A color television circuit characterized in that the horizontal scanning speed of an electron beam of a beam index type cathode ray tube is changed by changing the horizontal scanning speed of an electron beam of a beam index type cathode ray tube.