JPH02114770A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent deterioration in the picture quality without increasing the interval of scanning lines by expanding a spot size of an electron beam when number of horizontal scanning lines is less. CONSTITUTION:When a television signal of the NTSC system is received, switches 7, 8 are controlled by a control signal St supplied to a terminal 9, and a current of a parabolic waveform from a vertical parabolic waveform generating circuit 3 and a current of a parabolic waveform from a horizontal parabolic waveform generating circuit 5 are fed to an electromagnetic quartet pole 10 via the switches 7, 8. As a result, the current of the parabolic waveform of a horizontal period is modulated by the current of the parabolic waveform of one vertical period and fed to the pole 10 to form a magnetic field. Thus, the beam spot shape is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television receiver, and particularly to a television receiver capable of selectively displaying two television signals.

[Summary of the invention]

This invention provides a television receiver that selectively projects first and second television signals having different numbers of horizontal scanning lines on a cathode ray tube. By enlarging the spot size of the electron beam when the number of scanning lines is small, it is compatible with each television signal transmission method, even if the number of horizontal scanning lines (horizontal scanning line density) is different. This allows the display of high-quality images.

[Conventional technology]

Traditionally, HD TV (High Definit
ion TV), so-called high-definition, has been proposed. M is the transmission method for HDTV television signals.
The USE method is used.

The MUSE system is significantly different from the conventional NTSC system. For example, the number of scanning lines per frame is 1125 in the MUSE method as shown in Figure 14, whereas
In the NTSC system, there are 525 lines as shown in Figure 15, and in the MUSE system, the frequency band is 20 MHz to 30 MHz.
Hz, whereas in the NTSC system ~4.5 MHz
It is z. In addition, in the figure, 31 indicates a screen, and L indicates a raster.

As mentioned above, the MUSE system is used as the transmission system for HDTV television signals, while current television broadcasting is performed using the NTSC system, so a television receiver that can receive television signals from both systems is required. is desired. Therefore, a technique for selectively displaying television signals of both the MUSE system and the NTSC system has been proposed in Japanese Patent Laid-Open No. 61-224786.

[Problem to be solved by the invention]

In the above-mentioned television receiver that can selectively display television signals of both the MUSE system and the NTSC system, the following problems occur. That is, M
When displaying a television signal of the USE system, the beam spot is narrowed down to a predetermined diameter size corresponding to the number of scanning lines of the MUSE system, which is 1125. On the other hand, when displaying an NTSC television signal, N
Since the number of scanning lines in the TSC method is 525, the beam spot must be made larger than in the case of the MUSE method.
There was a problem in that the spacing between the scanning lines was large and the image quality deteriorated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a television receiver that can selectively display television signals with different horizontal scanning frequencies in an appropriate image state.

[Means to solve the problem]

This invention provides a television receiver that selectively projects first and second television signals having different numbers of horizontal scanning lines on a cathode ray tube. The configuration is such that the spot size of the electron beam is expanded when the number of scanning lines is small.

[Effect]

Using a television receiver that can selectively display the first and second television signals, the first television signal;
For example, when receiving a MUSE television signal and displaying an image, the beam spot is narrowed down evenly and sharply. This makes it possible to obtain beam spots and scanning lines suitable for MUSE television signals.

On the other hand, when receiving a second television signal, for example an NTSC television signal, and displaying an image, the beam spot is transformed to be vertically elongated. As a result, it is possible to prevent the interval between scanning lines from increasing and thereby to prevent deterioration of image quality, and it is also possible to obtain a beam spot and scanning lines suitable for an NTSC television signal.

In this way, even if the television signals have different numbers of horizontal scanning lines (horizontal scanning line densities), images of good quality can be displayed in accordance with the transmission method of each television signal.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 12. FIG. 1 shows a block diagram of the main parts of the television receiver according to this embodiment.

In FIG. 1, a terminal 1 is supplied with a vertical periodic signal PV, for example, a sawtooth wave with each vertical period, and a terminal 2 is supplied with a horizontal pulse PH. The above-mentioned vertical periodic signal pv is supplied to the vertical parabolic wave forming circuit 3.4, and the horizontal pulse Pv is supplied to the vertical parabolic wave forming circuit 3.4.
H is supplied to a horizontal parabolic waveforming circuit 5.6.

When the vertical parabolic wave forming circuit 3 and the horizontal parabolic wave forming circuit 5 described above receive an NTSC television signal, the vertical parabolic wave forming circuit 4 and the horizontal parabolic wave forming circuit 6 receive a MUSE television signal. When received, each outputs a parabolic waveform current. That is, when the vertical parabolic waveforming circuit 3.4 is supplied with the above-mentioned vertical periodic signal PV, it forms a parabolic waveform current of one vertical period, and this parabolic waveform current is supplied to the switch 7. In addition, the horizontal parabolic wave forming circuit 5.6 is
When the above-mentioned horizontal pulse PH is supplied, a parabolic waveform current having one horizontal period is formed, and this parabolic waveform current is supplied to the switch 8, and the vertical parabolic waveforming circuit 3.4 and the horizontal parabolic waveforming circuit 5.6, various circuits can be applied. For example, an integrating circuit or, although not shown, converts a parabolic waveform (corrected waveform) into digital data and stores it in a memory, outputs the digital data from the memory as appropriate, performs D/A conversion, and based on this digital data is output. A current having a parabolic waveform may be formed.

Switch 7.8 ensures that the received television signal is NT
It is controlled by a control signal St which becomes "0" or "1" depending on whether the SC method or the MUSE method is used.

When receiving NTSC television signals,
The control signal St becomes "0", and the terminal 7b of the switch 7,
7c is connected. 1 from vertical parabolic waveforming circuit 3
A parabolic waveform current with a vertical period is supplied to the coil 11 of the electromagnetic quadrupole 10 .

On the other hand, when receiving a MUSE television signal, the control signal St becomes P1, the terminals 7a and 7c of the switch 7 are connected, and the parabolic waveform of one vertical period from the vertical parabolic waveforming circuit 4 is output. Current is supplied to the coil 11 of the electromagnetic quadrupole 10.

Switch 8 is controlled similarly to switch 7 and is NTSC
When receiving television signals of the same system, switch 8
A parabolic waveform current of one horizontal period is transmitted from the horizontal parabolic wave forming circuit 5 through the terminals 8b and 8c of the electromagnetic quadrupole 10.
is supplied to the coil 11 of. On the other hand, when receiving a MUSE television signal, the switch 8 is connected to the terminal 8a.
, 8C, a parabolic waveform current of one horizontal period from the horizontal parabolic wave forming circuit 6 is applied to the coil 1 of the electromagnetic quadrupole 10.
1.

By the way, as shown in FIGS. 2 and 3, the three R, G, and B electron beams output from the double-beam electron gun (not shown) intersect at one point in the neck 12. ing.

Therefore, the electron beam bundle 13 at the point where three electron beams intersect (hereinafter referred to as electron beam intersection) is regarded as a single beam, and an electromagnetic quadrupole 1 is placed near this electron beam intersection.
0 and by changing the magnetic field, the Lorentz force is applied, and the electron beam flux 13 (i.e., the beam spot) is
The shape of the beam can be changed, and beam spot distortion can be corrected at the same time.

The electromagnetic quadrupole 10 carries a horizontally periodic parabolic waveform current,
A magnetic field is created by modulating and passing a current with a parabolic waveform of one vertical period. By controlling the parabolic waveform current flowing through the electromagnetic quadrupole 10 in a horizontal period, a Lorentz force is applied to the electron beam bundle 13, thereby changing its shape. The electromagnetic quadrupole 10 is provided on the neck portion 12 of the CRT, and the electromagnetic quadrupole 10 is
It is composed of a pair of U-shaped cores 14 and 15. Ends 14a, 14b, 15a of each core 14.15
, 15b are each wound with a coil 11. In this electromagnetic quadrupole 10, with the polarity shown in FIG. 2, the vertically elongated electron beam east 13 is subjected to the Lorentz force F by the magnetic field of the electromagnetic quadrupole 10, and becomes circular. In addition, in the polarity shown in FIG. 3, which is opposite to the polarity shown in FIG. 2, the horizontally elongated electron beam bundle 13 is subjected to the Lorentz force F by the magnetic field of the electromagnetic quadrupole 10, and becomes circular.

The circuit operation will be explained below.

When a MUSE television signal is received, a vertical periodic signal PV is supplied to a vertical parabolic wave forming circuit 3.4, and at the same time, a horizontal synchronizing pulse PR is supplied to a horizontal parabolic wave forming circuit 5.6.

A control signal St supplied to terminal 9 causes switch 7.
8 is controlled, and a parabolic waveform current from the vertical parabolic waveforming circuit 4 and a parabolic waveform current from the horizontal parabolic waveforming circuit 6 are supplied to the electromagnetic quadrupole 10 via the switch 7.8.

As a result, as shown in FIGS. 7 and 8, the current having a parabolic waveform with a horizontal period is modulated by the current having a parabolic waveform having one vertical period, and is supplied to the electromagnetic image electrode 10 to form a magnetic field. As a result, the beam spot shape is corrected.

This will be explained using FIGS. 4 and 5, FIGS. 8 and 9 as examples.

As shown in FIG. 4, on the CRT screen 16,
The shape of the beam spot BS before improvement is Lascou LL at the upper and lower ends, beam spot BSI at both left and right ends at L3,
BS3, BS7, and BS9 are horizontally long, and the central beam spots BS2 and BS8 are circular. These circular beam spots BS2 and BS8 have a size suitable for the MUSE method. In the raster L2 at the center, the central beam spot BS5 is vertically long, and the beam spots BS4 and BS6 at both left and right ends are circular.

A current having a parabolic waveform of one horizontal period corresponding to raster L1 in FIG. 4 is shown at 21 in FIG. If the current of this parabolic waveform of one horizontal period is further enlarged, the 9th
It will look like Figure B. That is, a current of a predetermined level flows at the beam spots BSI and BS3 at both the left and right ends shown in FIG. B.S.
3 is considered to be circular. Also, the central beam spot B52
Since no current flows at time 0, the electron beam flux 13 is not corrected and the beam spot BS2 remains circular. Therefore, beam spot B5 in raster L1
The l-B53 is evenly and sharply converged to form a circular shape, as shown in FIG. 9C. Note that beam spots BS7 to BS9 in raster L3 are also corrected in the same way as raster L1.

Next, a parabolic waveform current of one horizontal period corresponding to raster L2 in FIG. 4 is shown at 22 in FIG.

That is, since no current flows at the beam spots BS4 and BS6 at both left and right ends, the electron beam flux 13 is not corrected and the beam spots BS4 and BS6 remain circular. Furthermore, since a current with reversed polarity flows at the central beam spot BS5, the vertically elongated electron beam flux 13 is corrected into a circular shape by the magnetic field of the electromagnetic quadrupole 10, and the beam spot BS5 is made circular. . Therefore,
The beam spots BS4 to BS6 at the Lascoe L2 are uniformly and sharply focused into a circular shape, as shown in FIG. 9C.

As a result, the beam spot BS is all focused into a circular shape with a diameter r1 as shown in FIG. 5, and is suitable for displaying a MUSE television signal.

When receiving an NTSC television signal, the vertical periodic signal Pv is supplied to the vertical parabolic waveforming circuit 3.4, and at the same time, the horizontal pulse PH is supplied to the horizontal parabolic waveforming circuit 5.6.

A control signal St supplied to terminal 9 causes switch 7.
8 is controlled, and a parabolic waveform current from the vertical parabolic waveforming circuit 3 and a parabolic waveform current from the horizontal parabolic waveforming circuit 5 are supplied to the electromagnetic quadrupole 10 via the switch 7.8.

As a result, as shown in FIG. 10, the parabolic waveform current having a horizontal period is modulated by the parabolic waveform current having one vertical period, and is supplied to the electromagnetic quadrupole 10 to form a magnetic field. As a result, the beam spot shape is corrected.

This will be explained using FIGS. 4 and 6 and FIGS. 10 to 12 as examples.

A current having a parabolic waveform of one horizontal period corresponding to the raster L1 in FIG. 4 is shown at 23 in FIG. This one
If the horizontally periodic parabolic waveform current is further enlarged, it becomes as shown in FIG. 11B. That is, a current of a predetermined level flows in the beam spots BSI and BS3 at both left and right ends shown in FIG.
is stretched and corrected in the vertical direction by the magnetic field of Fig. 11C.
Vertical beam spots BSI, BS3 as shown in
Served. Furthermore, since the central beam spot BS2 shown in FIG. 11A is already circular, by supplying a slightly lower level of current, it is stretched vertically by the magnetic field of the electromagnetic quadrupole 10, and thereby A vertically long beam spot BS2 is formed. Therefore, the beam spots BSI to BS3 in the raster L1 are vertically elongated as shown in FIG. 11C. Note that the beam spots BS7 to BS9 in the Lascue L3 are also corrected in the same way as the Lascue L1.

Next, a parabolic waveform current of one horizontal period corresponding to raster L2 in FIG. 4 is shown at 24 in FIG. If the current of this parabolic waveform of one horizontal period is further enlarged, it becomes as shown in FIG. 12B. That is, current flows at the beam spots BS4 and BS6 at both left and right ends shown in FIG.
The beams are elongated in the vertical direction by the magnetic field, forming vertically long beam spots BS4 and BS6 as shown in FIG. 12C.

Furthermore, since the central beam spot BS5 shown in FIG. 12A is already vertically elongated, no current is supplied to it, and no correction is made to the beam spot BS5.

Therefore, beam spot BS4~ at Laskou L2
The BS6 is vertically elongated as shown in FIG. 12C.

As a result, the beam sub-1-BS is corrected into an ellipse with a length size r2 as shown in FIG.
This makes it suitable for displaying C-scheme television signals.

As is clear from the above description, even if the number of horizontal scanning lines changes, it is possible to prevent the interval between horizontal scanning lines from increasing, and to prevent image quality deterioration. In addition, it is possible to display images of good image quality in accordance with each transmission method such as the MUSE method and the NTSC method.

In addition, as shown in Fig. 4, the beam spot BS of a conventional television receiver is such that the diameter increases or deforms at the four corners or the center of the screen during boat fishing.
Although so-called beam spot distortion has occurred, according to this embodiment, beam spot distortion can also be eliminated at the same time.

By the way, in the present invention, the shape of the beam spot may be changed by controlling the focus without using the electrode quadrupole. An example is shown in FIG. Figure 13A shows beam spot B in the MUSE method.
FIG. 13B shows the beam spot BS in the NTSC system.

In this modification, when receiving an NTSC television signal, instead of making the beam spot BS into a vertically elongated ellipse, the shape of the beam spot BS is made larger overall by changing the focus voltage. .

Although this embodiment describes examples of television signals of the NTSC system and the MUSE system, the present invention is not limited to these and can be similarly applied to other high-definition television signals. Of course.

〔Effect of the invention〕

According to this invention, the spot size of the electron beam is enlarged when the number of horizontal scanning lines is small compared to when the number of horizontal scanning lines is large, so the spacing between the scanning lines does not become large and deterioration in image quality can be prevented. effective. Therefore, even if the television signals have different numbers of horizontal scanning lines (horizontal scanning line densities), it is possible to display images of good quality in accordance with the transmission method of each television signal.

Further, according to the embodiment, there is an effect that conventional beam spot distortion can also be eliminated at the same time.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Figs. 2 and 3 are illustrations of the operation of an electromagnetic quadrupole, and Figs. 4 to 6 show the shape and size of the beam spot, respectively. 7 and 8 are waveform diagrams showing the current supplied to the electromagnetic quadrupole, respectively. FIG. 9 is an explanatory diagram showing the beam spot and the current level for its correction, and FIG. 10 is the diagram. Waveform diagrams showing the current supplied to the electromagnetic quadrupole, Figures 11 and 1
2 is an explanatory diagram showing a beam spot and a current level for its correction, and FIG. 13 is an explanatory diagram showing a modified example, respectively.
FIGS. 14 and 15 are explanatory diagrams of conventional examples, respectively. Explanation of main symbols in the drawings 13: electron beam flux, L, LL, L2, L3 nira star, rl: diameter size, r2: length size.

Claims (1)

[Claims] In a television receiver that selectively displays first and second television signals having different numbers of horizontal scanning lines on a cathode ray tube, A television receiver characterized in that the spot size of an electron beam is expanded when the number of horizontal scanning lines is small.