JPS6053510B2 - 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, which increases the beam spot size and reduces sharpness.

In particular, in the horizontal contour portion 1 as shown in FIG. 1A and the line portion 2 as shown in FIG. 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, we obtain a second-order differential signal SB as shown in c in the same figure, and add this to the signal s° to obtain a video signal Sc with steep rise and fall as shown in D in the same figure, which is input to the picture tube. There is a way to supply it. However, in this method, the beam current increases more at the peak of the signal, so 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 supplied to an auxiliary deflection coil provided separately to correct the horizontal deflection magnetic field as shown in FIG.

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, as is clear from the figure, this method has the disadvantage that the width of the light-emitting portion on the screen does not correspond to the time width of the video signal SO and becomes narrow.

Furthermore, in this case, there is a disadvantage that the width of the light-emitting portion on the screen becomes narrower as the level of the scanning speed modulation signal is increased and the scanning speed is more strongly modulated. In view of the above-mentioned points, this invention prevents the width of the light-emitting portion from becoming narrower even when the scanning speed is modulated, and furthermore, the width of the light-emitting portion remains constant regardless of the degree of modulation of the scanning speed. It was made so that it would become so.

FIG. 4 is an example of this, in which the original video signal SO (FIG. 7A) taken out through the video amplifier 10 is differentiated by a differential signal generation circuit, for example, a differential circuit 11, and a differential signal SA is generated.
(B in the same figure) is obtained, and this differential signal SA is sent to the polarity inversion circuit 12.
is supplied to the same polarization circuit 13 having a polarization circuit 13 to obtain a signal SO (C in the same figure) in which the polarity of the portion of the signal SA corresponding to the falling edge of the video signal SO is inverted, and this signal SD is sent to a variable gain amplifier. 14, and in the synthesizer 15, the signal S8(
D) in the same figure is synthesized.

This polarization circuit 13 and variable gain amplifier 14 constitute a correction signal generation circuit. In this way, a video output signal Sp'' (E in the same figure) in which the width of the white signal is made wider than that of the original video signal SO is obtained from the synthesizer 15 as a signal addition circuit, for example. Signal Sp to picture tube 1
The electron beam is supplied to the cathode 17 of No. 6 to density-modulate the electron beam. On the other hand, for example, the video output signal S, is differentiated by the differentiating circuit 20 in the scanning speed signal processing circuit to obtain the differential signal SvO (F in the same figure). The signal Sv obtained from the amplifier 21 is supplied to a gain amplifier 21, and the signal Sv obtained from the amplifier 21 is supplied as a scanning speed modulation signal to a scanning speed modulation deflection means 19 provided separately from the horizontal and vertical deflection means 18 in the picture tube 16, for example. , modulates the scanning speed of the electron beam on the screen of the picture tube 16.

This scanning speed modulation deflection means 19 can be constructed by arranging two electrostatic deflection plates facing each other in the horizontal direction within the neck of the tube 16 on the near side of the deflection means 18. Here, the gains of the variable gain amplifiers 14 and 21 can be changed simultaneously by adjusting the variable resistor 22 as a gain adjustment means for the limbal correction amount, and when the gain of the amplifier 21 is increased, the gain of the amplifier 14 so that the gain can be changed in a direction such that the gain is also increased.

According to this invention, the reduction in the width of the light emitting portion due to modulation of the scanning speed described above is corrected by widening the width of the white signal of the video signal itself.

Moreover, in this case, when the gain of the amplifier 21 is increased to increase the level of the scanning speed modulation signal and the scanning speed is more strongly modulated, the width of the light emitting portion is reduced by the scanning speed modulation. The larger the width of the white signal in the video output signal Sp is, the wider the width of the white signal in the video output signal Sp becomes. Therefore, regardless of the strength of the scanning speed modulation, the light emission distribution becomes uniform as shown by line 5 in FIG. The width is a constant value corresponding to the time from the midpoint of the rise to the midpoint of the fall of the original video signal SO. As in the example shown in FIG.
1 to obtain the scanning speed modulation signal Sv.

Further, the signal to be combined with the original video signal SO may be a second-order differential signal as shown in FIG. 71, instead of the first-order differential signal SA of the original video signal SO as described above, or It may be something like a combination of these at an appropriate level ratio.

The scanning speed modulation deflection means 19 can also be constructed by specially forming, for example, a focusing electrode of the electron gun of the picture tube 16, as shown in FIG. That is, in FIG.
This figure shows the electron gun in the neck part of , which includes a cathode 30, a control electrode 31, an accelerating electrode 32, a first anode 33, and a focusing electrode 3.
4 and the second anode 35 are sequentially arranged on the same axis. The focusing electrode 34 is divided into two parts each having a shape similar to that of a single cylindrical body cut by a plane that is perpendicular to the horizontal plane at the middle part and diagonally intersects with the tube axis.
Consisting of electrode parts 34A and 34B, the electrode part 34A
and 34B are respectively supplied with a focusing voltage of zero V to several KV, and superimposed thereon, the above-mentioned scanning speed modulation signal Sv is supplied between both electrode portions 34A and 34B.
Therefore, a horizontal electric field is generated by the signal Sv at the location of the focusing electrode 34, which deflects the beam 36 horizontally 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.

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 Description of the Drawings] Figures 1 to 3 are diagrams for explaining the present invention, Figures 4 and 5 are system diagrams of an example of the present invention, and Figure 6 is a deflection for scanning speed modulation. FIG. 7 is a sectional view of two examples of the means and a waveform diagram for explaining the present invention. 10 is a video amplifier, 11 and 20 are differentiating circuits, 13 is a polarization circuit, 14 and 21 are variable gain amplifiers, and 16 is a picture tube.

Claims (1)

[Claims] 1. A differential signal generation circuit that extracts this differential component from the original video signal, and inverts the negative polarity component of this output and adds it to this positive polarity component to correct the same polarity at the rising and falling parts of the video signal. a correction signal generation circuit that obtains a signal; a signal addition circuit that adds this output to the original video signal via a variable gain amplifier to obtain a video output signal in which the width of the white signal is expanded; a scanning speed signal processing circuit that generates a scanning speed modulation signal from the original video signal; a scanning speed modulation deflection means that is driven by the output of the circuit and modulates the scanning speed of the electron beam; In addition to providing respective gain adjustment means for controlling, the control output of the gain adjustment means is also supplied to the scanning speed signal processing circuit, so that the level of the correction signal and the modulation degree of the scanning speed modulation are linked and simultaneously controlled. A television receiver characterized by being variable.