JPS593668Y2 - Beam index type color television receiver - Google Patents

Description

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

Such a color television receiver has three primary color phosphors R and G on the inner surface of the face plate 2 of the picture tube 1, as shown in FIG.
, B are sequentially arranged in a striped manner so as to sandwich the black guard band 3, and a first index element 5 made of a short-lasting phosphor is arranged on the inner surface of the index element 5 through an aluminum film 4.
are arranged repeatedly in a certain relationship, and the first index element 5 is located at the end thereof, particularly at a location that precedes the phosphors R, G, B and the first index element 5 with respect to the horizontal scanning of the electron beam. 1st with different period (+ in frequency)
When a small number of index elements 6 are provided and the electron beam emitted from the single electron gun is swept, the run-in signal obtained from the second index element 6 and the index signal obtained from the first index element direct the electron beam to a predetermined phosphor. It is designed to be shocking.

More specifically, as shown in the block diagram of FIG. 2, an index signal obtained from a photoelectric converter 7 provided in the funnel portion of the picture tube 1 is filtered by a filter 8 and applied to an index processing circuit 9. Here, the video signal S (including color information) is converted into the arrangement period of the three primary color phosphor stripes, that is, the triplet repetition frequency (hereinafter referred to as "triplet frequency"), and is separately supplied to the next coupling circuit 10. This modulates the electron beam, thereby controlling the electron beam.

In FIG. 2, 11 is a deflection circuit, and 12 is a deflection yoke.

A conventional example of the index processing circuit is shown in FIG.

In this conventional example, the first monostable multivibrator 13 is driven at the leading edge of the horizontal synchronizing signal a (see FIG. 4a) to obtain a delayed signal d.

The output pulse of the first monostable multivibrator 13 has a width that allows stable extraction of the line signal.

The Q output of the first monostable multivibrator 13 and the line signal S are ANDed by an AND circuit 14, and the first pulse of this AND output is used to activate the second monostable multivibrator 15.
is operated to obtain the output e.

In the example of FIG. 4, the trailing edge of said e is between the first and second pulses of index signal C.

The output e of the second monostable multivibrator 15 and the inverted signal C of the index signal C by the inverter 16 are ANDed by an AND circuit 17, and this output f is inputted to a ternary counter 18.

The ternary counter 1B is reset by the output e of the second monostable multivibrator 15.

The output of each bit of the ternary counter 18 is input to a decoder 19 at the next stage.

As a result, for example, a triplet frequency pulse train signal g (see FIG. 4g) synchronized with the arrangement of the phosphors R is obtained.

A timing signal generation circuit 20 to which this signal g and index signal C are supplied further generates a triplet frequency pulse train signal (not shown) synchronized with each of the G and B arrays.

Therefore, from the timing signal generation circuit 20, R, G,
Three signals with triplet frequencies synchronized with each of B are obtained.

However, conventional television receivers using such index processing circuits have the drawback of malfunctions in color reproduction, which is not desirable.

For example, the horizontal synchronization signal contains jitter components and
Figure 4e shows that it is difficult to detect a constant line signal across all horizontal scanning lines because the period changes as the PL changes, and the horizontal scanning speed of the electron beam differs between the upper and lower parts of the screen and the central part of the screen. When extracting the index signal C with the pulse of This will cause .

In addition, in the case of the conventional example, the trailing edge of FIG. Within 100 n5ec, such tolerance is within the first and second monostable multivibrator 13.15
It will also be broken due to temperature drift, so
From this point of view as well, the conventional example is not suitable.

In view of this, the present invention is a beam index type color television receiver that realizes an index processing circuit without using a monostable multivibrator and can operate stably even under changes in horizontal deflection speed and temperature. This is a proposal for a machine.

As shown in Fig. 5, the index processing circuit in the beam index type color television receiver of the present invention counts line signals using a horizontal synchronizing signal as a reset signal, and outputs the mth (m is a positive integer) pulse to each horizontal pulse. an m-ary counter 22 for taking out only one piece per line; a PLL circuit 25 for converting the run-in signal during the run-in period to the same frequency as the index signal;
An OR circuit 27 takes the logical sum of the output of the LL circuit 25 and the index signal C, and the output from the m-ary counter 22 side is used as a reset signal to count the output signal of the OR circuit 27 and output a triplet frequency signal. A counter 28 is provided.

The output of the counter 28 is converted by a decoder 29 into a triplet frequency pulse train signal synchronized with, for example, R as shown in FIG. 4k.

30 is a timing signal generation circuit that generates triplet frequency signals synchronized with each of R, G, and B.

In FIG. 5, 23 is a decoder that reads the contents of each bit of the m-ary counter 22, and creates m-1 logic.

24 is an AND circuit which performs a logical product of the output of the decoder 23 and the line signal, and its output is shown in FIG.

This output signal serves as a reset signal for the ternary counter 28 as described above.

The signal input to the PLL circuit 25 is a line signal, and has a frequency of, for example, 3 MHz.

This PLL circuit 25 has a frequency three times that of the line signal (9M
Hz) signal [Fig. 4 i].

This signal has the same frequency as the index signal obtained from the first index element 5.

The phase control signal of the PLL circuit 25 is a signal obtained by dividing the 9 MHz output by the frequency divider 26.

In the circuit shown in FIG. 5, m of the m-ary counter 22 is set to 2, so when two pulses of the line signal input to the terminal 21 are input, the m-ary counter 22 stops and the contents are transferred to the coder 23. give to

The coder 23 reads this and the AND circuit 24
Since the run-in signal is ANDed, the output of the AND circuit 24 is as shown in the fourth diagram.

On the other hand, in the PLL circuit 25, the fourth
As shown in FIG. 4, a signal having the same frequency as the index signal is output during the line period, and this signal is added to the index signal C in the OR circuit 27, so a second index element 6 is provided as shown in FIG. 4J. This means that the index signal is substantially obtained even in the portion where the index signal is located.

When converting to a triplet frequency, the start timing is the second pulse of the run-in signal [Figure 4h
] will be carried out.

In this way, the present invention creates a triplet frequency timing signal without using any monostable multivibrator, which is easily affected by temperature.

The output i of the PLL circuit 25 is sent to the decoder 28 because it does not change as much as the number of pulses even if the horizontal scanning speed of the electron beam changes and the frequency of the run-in signal changes somewhat.
The phase of the output is maintained correctly.

Therefore, according to the present invention, hues can be stably reproduced in a beam index type color television receiver even if there are changes in the horizontal scanning speed of the electron beam or changes in the temperature of the circuit.

[Brief explanation of drawings]

FIG. 1A 90 is a plan sectional view and a rear view showing the inner surface of the face plate of a picture tube in a beam index type color television receiver, and FIG. 2 is a schematic diagram of the beam index type color television receiver. FIG. FIG. 3 is a block diagram showing the main parts of the conventional example, and FIG. 4 is an explanatory diagram. FIG. 5 is a block diagram showing the main parts of a beam inch type color television receiver embodying the present invention. R, G, B... Three primary color phosphors, a...
・Horizontal synchronization signal, b...Run-in signal, C...
. . . index signal, 5 . . . first index element, 6 . . . first index element,
22...m-ary counter, 25...PL
L circuit, 27...OR circuit, 2B...
counter.

Claims (1)

[Scope of utility model registration request] Three primary color phosphors of red, green, and blue are repeatedly arranged in a stripe pattern, and a first index element is repeatedly arranged in a stripe pattern in regular relationship with these phosphors. When an electron beam emitted from a single electron gun is swept over a surface consisting of a phosphor and a small number of second index elements provided at a location preceding the first index element and with a period different from that of the index elements. A triplet frequency control signal is generated by the line signal obtained from the second index element and the index signal obtained from the first index element, and the video signal is modulated by the control signal so that the electron beam hits a predetermined phosphor. In a beam index type color television receiver designed to generate shocks, the horizontal synchronization signal is used as a reset signal to count the run-in signal, and the mth (m
is a positive integer) for each horizontal line; a PLL circuit that converts the run-in signal during the run-in period to the same frequency as the index signal; and the output of the PLL circuit. A beam index type comprising: an OR circuit that receives an index signal as an input, and a counter that uses the output of the m-ary counter as a reset signal to count the output signal of the OR circuit and output a triplet frequency signal. Color television receiver.