JPH0145182Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a beam index type color television receiver.

As shown in FIG. 1, such a color television receiver has three primary color phosphors R, G, and B repeatedly arranged in stripes on the inner surface of a face plate 2 of a picture tube 1, sandwiching a black guard band 3. At the same time, a first index element 5 made of a short-lasting phosphor is attached to the inner surface of the index element 5 through a metal back 4 made of an aluminum vapor-deposited film, and the three primary color phosphors R,
An electron beam emitted from a single electron gun was swept over a surface in which a second index element 6 was repeatedly arranged in a certain relationship with G and B and was provided in a position preceding the first index element in terms of horizontal deflection. In this television receiver, the index signal obtained from the index element is used to control the electron beam to impact predetermined three primary color phosphors.

More specifically, as shown in FIG. 2, the optical signal 7 generated from the index element is converted into an electrical signal by a photoelectric converter 8 provided in the funnel portion of the picture tube 1, and the resulting index signal is passed through a filter. 9 and applied to an index processing circuit 10, where the index signal is extracted for a certain period of time by an index extraction pulse whose generation point is determined by the horizontal synchronization signal and the index signal obtained at the start of horizontal scanning, This is converted into a phosphor array period, ie, a triplet repetition frequency. Then, the next mixing circuit 11
is mixed with the color signal and modulated by the color signal.
It is applied to the grid electrode of the picture tube 1.

In FIG. 2, a video signal processing circuit 12 supplies a 3.58 MHz color subcarrier k and a color signal m to the mixing circuit 11, and also supplies a luminance signal to the cathode electrode of the picture tube 1. 13 is a deflection circuit, and 14 is a deflection yoke. The details of the index processing circuit 10 are as shown in the circuit diagram of FIG. 3 and the signal waveform diagram of FIG. 4, including a first monostable multivibrator 15 that delays the horizontal synchronizing signal a;
an RS flip-flop 16 which uses the first monostable multivibrator 15 as a reset input and receives a set input of the line signal b based on the second index element 6; and a second monostable which delays the output of the RS flip-flop 16 and outputs a pulse e. A multivibrator 17, a third monostable multivibrator 18 that further delays the multivibrator 17, and a D that uses the output f of the third monostable multivibrator 18 as a data input, and uses the index signal c as a clock input to generate an index extraction pulse g. A flip-flop 19, an AND circuit 20 which inputs the index extraction pulse g and the index signal c and extracts an index signal, and a ternary counter which is reset by the index extraction pulse g and counts down the extracted index signal. 21, a decoder 22 that decodes the counter output, and a bandpass filter 23 that converts the triplet repetition frequency pulse i given from the decoder 22 into a sine wave signal j.
It has

On the other hand, as shown in FIG. 5, the mixing circuit 11 includes a first mixer 24 that mixes the sine wave signal j and the 3.58 MHz color subcarrier k and calculates the sum of their frequencies;
A second mixer mixes the output l of the first mixer 24 and the color signal m and outputs a signal n of the frequency difference between them.
It has a mixer 25.

By the way, the passband of the second mixer 25 is t±0.5M, where t is the triplet repetition frequency.
Hz or higher, but the color signal within this band is 3.58±0.5)
MHz, the color signal components before and after the index extraction pulse g are output as they are, but in this case, the run-in signal b is modulated by the color signal in the portion before the index extraction pulse g. In the index processing circuit 10
The position of the trailing edge of the delayed output e from the RS flip-flop 16 shifts, resulting in malfunction. still,
To explain in more detail why the run-in signal b is modulated by the color signal, the run-in signal is obtained when the second index element 6 is swept with an electron beam, but since the electron beam is modulated by the color signal, This is because if the second index element 6 is swept with an electron beam modulated by this color signal, the resulting run-in signal will be modulated by the color signal. Therefore, the first index signal extracted by the index extraction pulse g is not uniform, resulting in a hue error. For example, it is assumed that i and its corresponding sine wave signal j match the phase of blue phosphor B, and the phase of the sine wave is modulated with a color signal to reproduce the hue, so that the phases of i and j are This is because if it does not uniformly match the phosphor B, the hue will be incorrect and the color will be reproduced.

The present invention proposes a beam index type color television receiver which eliminates the above-mentioned drawbacks with a simple structure.

FIG. 6 shows the mixing circuit 11 of a beam index type color television receiver in which the present invention is implemented.Compared to the conventional example, the mixing circuit 11 has a mixing output that is effective only during the period of the index extraction pulse g. The difference is that means 26 for doing so is provided. Therefore, the signal given from the mixing circuit 11 to the grid electrode of the picture tube 1 is only during the period of the index extraction pulse g, as indicated by n', and since no color signal is given to the grid electrode before the pulse g, the color signal is Line pulse b is not modulated by . The means 26 is constituted by, for example, an analog switch, and the index extraction pulse g, which is the output of the D flip-flop 19 in the index processing circuit 10, is used as its on/off control signal.

The embodiment shown in FIG. 7 is a case where the means 26 is provided on the color signal input side of the second mixer 25, but even in this case, the same effect as shown in FIG. 6 can be obtained.

As explained above, according to the present invention, the malfunction in which the phase of the extraction index pulse becomes uncertain due to modulation of the run impulse by the color signal is avoided, and normal color reproduction is possible, which is extremely effective. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the inner surface of the face plate of a picture tube used in a beam index color television receiver, and FIG. 2 is a schematic block diagram of the beam index color television receiver. Figure 3 is a detailed diagram of a part of it. FIG. 4 is a signal waveform diagram for explaining the conventional example and the present invention. FIG. 5 is a circuit diagram showing the main parts of a conventional example. FIG. 6 is a circuit diagram of a main part of a beam index type color television receiver embodying the present invention, and FIG. 7 is a circuit diagram of another embodiment of the present invention. 1... picture tube, 2... face plate, 5,
6... Index element, 11... Mixing circuit, 2
6... Switch means, R, G, B... Three primary color phosphors, a... Horizontal synchronization signal, b... Run-in signal,
g...Index extraction pulse.

Claims (1)

[Scope of claim for utility model registration] (1) Red, green, and blue primary color phosphors R, G, and B repeatedly arranged on the inner surface of the face plate of the picture tube;
and index elements 5, 5, repeatedly arranged in a striped manner in regular association with the phosphor.
5, 6, and means 8, 9 for detecting an index signal obtained from the index element when the surface consisting of the phosphor and the index element is swept with an electron beam emitted from a single electron gun.
and means 15, 16, 17, 18, 1 for creating an extraction pulse g whose generation timing is determined by the line signal b obtained at the start of horizontal scanning among the index signals and the horizontal synchronization signal a.
9, extraction means 20 for extracting the index signal using this extraction pulse g, and means 21 and 2 for converting this extracted index signal h into a triplet frequency signal j.
2, 23, and this triplet frequency signal j and color signal m
In the beam index type color television receiver, the electron beam before the extraction pulse g is modulated by the color signal m. The output side of the mixing means 24, 25 or the color signal of the mixing means 24, 25 is controlled by the extraction pulse g in order to enable the mixing output only during the period of the extraction pulse. On the input side of m,
A beam index type color television receiver characterized in that it is provided with switch means 26, 26 provided therein. (2) Claim 1 of the utility model registration characterized in that the switching means is an analog switch.
A beam index type color television receiver as described in 2.