JPS6048946B2 - television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When displaying an image on a television receiver, the beam current of the picture tube increases in areas with high brightness, resulting in a beam spot size that becomes large and a decrease in sharpness.

In particular, in the horizontal ring part 1 as shown in Figure 1A and the line part 2 as shown in Figure 1B, the original video signal is
As shown in Figure A, there is a sharp change between the black level and white level, but due to the frequency characteristics of the receiver's transmission system, the high-frequency components are attenuated, so the signal becomes distorted as shown in Figure B. Horizontal sharpness is further reduced. Therefore, as a method of compensating for the decrease in sharpness, the video signal 50 shown in FIG.
From this, a second-order differential signal SB as shown in C in the figure is obtained, and this is added to the signal 50 to obtain a video signal Sc with steep rises and falls as shown in D in the figure, which is sent to the picture tube. There is a way to supply it. However, in this method, since the beam current increases more at the peak of the signal, the beam spot size becomes larger, so the sharpness is not improved as much.

As another method, the video signal 50 shown in FIG. 3A is supplied as is to the picture tube, and this video signal 50 is differentiated to obtain a signal SA shown in FIG. There is a method in which the horizontal deflection magnetic field is corrected as shown in Figure C by supplying it to a separately provided auxiliary deflection coil, thereby modulating the scanning speed of the beam on the screen as shown in Figure D.

According to this method, the scanning speed of the beam increases in the section Ta, and the amount of light emitted at the corresponding point on the screen decreases.
In section 1, the scanning speed of the beam slows down and the amount of light emitted at the corresponding point on the screen increases, so considering the spot size of the beam, the amount of light emitted in the horizontal direction on the screen is as shown in Figure 3E. horizontal sharpness is improved. However, when using this method, as is clear from the figure, the width of the light emitting part on the screen is the video signal S.

The disadvantage is that it does not correspond to the time span of , and becomes thin. In response to this, by correcting the waveform of the video signal and at the same time devising the waveform of the scanning speed modulation signal, we have eliminated the drawbacks of the method shown in Figure 3 and further improved the sharpness. There is a way. As shown in FIG. 4, this is the original video signal S with respect to the original video signal SO.

The correction signals formed by differential processing are combined to generate the original video signal S. Obtain a video output signal S, with a white signal width wider than that of , and supply this video output signal Sp to a picture tube to density-modulate the electron beam, while differentially processing the original video signal SO. Accordingly, the video output signal Sp
In the rising and falling parts, the polarities are opposite to each other, and the positions of the positive and negative peaks are the starting point of the rising part and the end of the falling part. A signal Sv that appears at a dotted position is obtained, and this signal Sv is used as a scanning speed modulation signal to modulate the scanning speed of the electron beam on the screen of the picture tube. In this way, the horizontal scanning position of the electron beam on the screen with respect to the passage of time is the fourth
The light emission distribution in the horizontal direction on the screen becomes as shown by line 4 in the figure, and the light emission distribution in the horizontal direction on the screen becomes as shown by line 5 in the figure.

That is, as shown in FIG. 5, the scanning speed modulation 4 signal Sv suddenly rises at the rising edge point X of the video output signal Sp, so the scanning speed of the beam suddenly increases, and the beam The position immediately reaches point Y1 in the figure, and the amount of light emission is suppressed up to this point Y1. As the scanning speed modulation signal Sv gradually decreases from its maximum positive value, the scanning speed of the beam gradually slows down, and at each point in time of the rising edge of the video output signal Sp, , X3, X. , the beam positions are at points Y2, Y3, and Y4. On the other hand, the video output signal S
The falling part of p is completely symmetrical to this. Therefore, the fact that the electron beam is density-modulated by the video output signal Sp and the scanning speed of the beam on the screen is modulated by the scanning speed modulation signal Sv is as if the rising and falling edges are normal as shown by the broken line in the figure. The density of the electron beam is modulated by the steep video signal SR, and the scanning speed of the beam on the screen becomes equal to that when no modulation is performed, and the horizontal light emission distribution on the screen becomes as shown by line 5 in the figure. As is clear from this, the sharpness is further improved, and the width of the light emitting portion corresponds to the time from the midpoint of the rise to the midpoint of the fall of the original video signal S. Unlike the method shown in FIG. 3, it does not become thinner. At this point, a video output signal Sp with a wider white signal width than the original video signal SO
To obtain the original video signal S.

However, it is necessary to select the polarity and level and synthesize not only the first-order differential signal but also the second-order and higher-order differential signals. Furthermore, in order to obtain a scanning speed modulation signal Sv with a steep rise in which the positions of its positive and negative peaks are closer to the start point of the rising portion and the end point of the falling portion of the video output signal Sp, the video signal S. It is necessary to select the polarity and level and synthesize the second-order or higher-order differential signals with respect to the first-order differential signal. The present invention enables the above-described video output signal SP and scanning speed modulation signal Sv to be easily formed by using a second-order or higher-order differential signal with a simple configuration. FIG. 6 shows an example of this, where 10 is an image amplifier, 11 is a picture tube, in the picture tube 11, 12 is a cathode, 13 is horizontal and vertical deflection means, and 14 is another deflection means for scanning speed modulation. be.

This scanning speed modulation deflection means 14 can be constructed, for example, by arranging two electrostatic deflection plates in the neck portion of the tube 11 so as to face each other in the horizontal direction. Then, the original video signal S is extracted through the video amplifier 10.

(Fig. 8A) is supplied to the first-order differentiator circuit 21 and differentiated.
A second differential signal SA (B in the same figure) is obtained. This first-order differential signal S
A is supplied to a polarization circuit 27 having a polarity inversion circuit 26, and is a video signal S of the signal SA. By inverting the polarity of the portion corresponding to the falling edge of , a signal SD having the same polarity (C in the figure) is obtained. 5. Then, the signal SD having the same polarity is supplied to the second-order differentiation circuit 22D belonging to the first system and differentiated to obtain a second-order differentiation signal SD.

(D in the same figure) is obtained. Furthermore, if necessary, a second-order differential signal SD. is supplied to the third-order differential circuit 23D and differentiated to obtain a third-order differential signal SD. l (E in the same figure) is obtained, and this third-order differential signal S
D. is supplied to the fourth-order differential circuit 24D and differentiated to obtain a fourth-order differential signal SD. Then, higher-order differential signals are obtained in sequence. On the other hand, the first differential signal SA (B in the same figure)
is supplied to the second-order differentiation circuit 22A belonging to the second system 1 and differentiated, thereby producing a second-order differentiation signal SA.

(Figure F) is obtained. Furthermore, if necessary, the second-order differential signal SA. is supplied to the third-order differentiation circuit 23A and differentiated to produce a third-order differential signal SA. (G in the same figure) is obtained, and this third-order differential signal SA
3 is supplied to the fourth-order differential circuit 24A and differentiated to obtain the fourth-order differential signal SA, . . . . And the first matrix circuit 2
8, the original video signal SO and the same polarization circuit 27
output signal SD and each output signal of the odd-order differentiator circuit belonging to the first system, that is, the third-order differentiator circuit 23D) the fifth-order differentiator circuit 2
5D... output signal SD3, SD,,...
. . . and each output signal of the even-order differentiation circuit belonging to the second system, that is, the second-order differentiation circuit 22A, the fourth-order differentiation circuit 24A, etc.
...'s output signals SA2, SA4, ......,
By adding them at a predetermined level ratio with their polarities unchanged, the matrix circuit 28 obtains the video output signal S, (FIG. 8H) in which the width of the above-mentioned white signal is widened.

'Meanwhile, in the second matrix circuit 29, the output signal SA of the first-order differentiator 21 and each output signal of the even-order differentiator circuit belonging to the first system, that is, the second-order differentiator circuits 22D, 4
Output signals SD2, SD of the order differentiating circuit 24D...
.

, . . . and the respective output signals of the odd ι order differentiating circuits belonging to the second system, that is, the output signals SA3, SA5, .
By adding .
A scanning speed variation signal Sv (FIG. 8I) with a steep rise approaching the start point of the rising portion and the end point of the falling portion of is obtained. Then, the video output signal Sp is supplied to the cathode 12 of the picture tube 11 to density-modulate the electron beam, and the scanning speed modulation signal Sv is sent between the two mutually opposing electrostatic deflection plates of the scanning speed modulation deflection means 14. is supplied to modulate the scanning speed of the electron beam on the screen of the tube 11.

The scanning speed modulation deflection means 14 can also be constructed by specially forming, for example, a focusing electrode of the electron gun of the picture tube 11, as shown in FIG.

That is, FIG. 7 shows the electron gun inside the neck of the tube 11, which includes a cathode 30, a control electrode 31, an accelerating electrode 32, a first
An anode 33, a focusing electrode 34, and a second anode 35 are sequentially arranged on the same axis.

Then, the focusing electrode 34 is divided into two electrode parts 34A having a shape similar to that of a single cylindrical body cut by a plane that is orthogonal to the horizontal plane at the middle part and diagonal to the tube axis. A focusing voltage of zero V to several KV is supplied to each of the electrode parts 34A and 34B, and both electrode parts 34A and 34B are connected by weight.
The above-mentioned scanning speed modulation signal Sv is supplied between 4B and 4B.
Therefore, a horizontal electric field is generated by the signal Sv at the position of the focusing electrode 34, which deflects the beam 36 in the horizontal direction and modulates the scanning speed of the beam 36 on the screen. Alternatively, the horizontal deflection coil may also be used as the deflection means for scanning speed modulation, and a combination of the above-mentioned scanning speed modulation signal and the horizontal deflection signal may be supplied thereto.

According to this invention, the desired video output signal and scanning speed can be obtained by using a simple configuration that includes a common first-order differentiating circuit, a same polarization circuit, a necessary number of differentiating circuits, and two matrix circuits. Modulation signals can be easily formed.

Note that the present invention can also be applied to a color television receiver, and in this case, the luminance signal may be treated as the above-mentioned video signal.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams for explaining this invention, Figures 4 and 5 are diagrams for explaining the method that is the premise of this invention, and Figure 6 is a system diagram of an example of this invention. , FIG. 7 is a sectional view of an example of the deflection means for scanning speed modulation, and FIG. 8 is a waveform diagram for explaining the present invention. 10 is a video amplifier, 11 is a picture tube, 21 is a first-order differentiating circuit, 27 is a polarizing circuit, 22D, 23D, . . . are second-order or higher order differentiating circuits of the first system, 22A, 23A.・
. . . are second-order or higher-order differential circuits of the second system, and 28 and 29 are first and second matrix circuits.

Claims (1)

[Claims] 1 A first-order differentiation circuit that differentiates the original video signal and this 1
Based on the same polarization circuit that makes the polarity of each signal part corresponding to the rising and falling parts of the original video signal of the output signal of the second-order differentiating circuit the same, and the output signal of this same polarization circuit, A first system of second-order or higher-order differentiating circuits that sequentially differentiates the output signals of the previous-stage circuits, and a second system that sequentially differentiates the output signals of the previous-stage circuits based on the output signals of the first-order differentiator circuits. 2
The above differentiating circuit, the original video signal, the output signal of the same polarization circuit, each output signal of the odd differentiating circuit belonging to the first system, and the even differentiating circuit belonging to the second system. a first matrix circuit that synthesizes each output signal to obtain a video output signal with a white signal wider than the original video signal; an output signal of the first-order differential circuit; and a first system. a second matrix circuit that synthesizes each output signal of the even order differential circuit belonging to the second system and each output signal of the odd order differential circuit belonging to the second system to form a scanning speed modulation signal corresponding to the video output signal; A television receiver, wherein the video output signal is applied to a picture tube, and the scanning velocity of an electron beam on the screen of the picture tube is modulated by the scanning velocity modulation signal.