JPH07312702A - Television receiver - Google Patents

Abstract

PURPOSE:To obtain a television receiver in which the difference of the optical output between the middle part of the screen and a peripheral part even when a video software whose aspect ratio is 4:3 is displayed on the entire screen of a CRT whose aspect ratio is 16:9. CONSTITUTION:The television receiver is provided with a horizontal deflection circuit 21 that deflects a signal so as to extend the linearity of horizontal deflection in the middle part of the screen up to left and right peripheral parts in order to display a video software whose aspect ratio is 4:3 is displayed on the entire screen of a CRT whose aspect ratio is 16:9, with a correction waveform generating means 20 generating a parabolic wave of a horizontal period, with a modulation means 18 modulating the amplitude of a video signal with the output signal of the correction waveform generating means 20 and with a switching means 3 arranged between the correction waveform generating means 20 and the modulation means 18. Then the switching means 23 is closed when the linearity is switched to be extended up to the peripheral parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a horizontally long screen whose aspect ratio is larger than 4: 3.

[0002]

2. Description of the Related Art FIG. 8A shows an aspect ratio of 16: 9.
4 is a display example in which a 4 to 3 image is displayed on the CRT display surface. FIG. 8B is a display example in which the horizontal linearity of the horizontal deflection circuit is extended in the left and right peripheral portions compared to the central portion to emphasize the wide feeling. The perfect circle or ellipse on the display surface is drawn to show the linearity of the screen.

In FIG. 7, the horizontal deflection width is switched to the above-mentioned 2
It is a high voltage generation / horizontal deflection circuit of a conventional wide television capable of displaying modes. In the figure, 1 is a CRT, 2 is a high voltage and focus required for the CRT 1, a flyback transformer for supplying a screen voltage, 3 is a horizontal deflection coil, 4 is a horizontal linearity correction coil, 5 is a horizontal output transistor, and 6 and 7 are capacitors. , 8 and 9 are damper diodes, 10 is an S-shaped correction capacitor,
Reference numeral 11 is a diode modulator modulation coil, 12 is its output transistor, 13 is an additional S-shaped correction capacitor, 14 is a switch, and 15 is a power supply.

Next, the operation will be described. The horizontal pincushion distortion of the horizontal deflection circuit is corrected by a diode modulator type circuit. In the horizontal deflection operation, the coil on the primary side of the flyback transformer 2 functions as a choke coil of the power supply 15, and the switching operation of the transistor 5 is used to flow a horizontal cycle sawtooth wave current to the horizontal deflection coil 3. . That is, in the first half of horizontal deflection, the transistor 5 is turned off, the damper diode 8 is turned on, and a current flows through the damper diode 8, the horizontal deflection coil 3, the horizontal linearity coil 4, and the S-shaped correction capacitor 10 in this order. In the latter half of horizontal deflection, the transistor 5
Is turned on, and a current flows from the S-shaped correction capacitor 10, the horizontal linearity coil 4, and the horizontal deflection coil 3 to the transistor 5. In the blanking period, resonance current flows due to resonance between the horizontal deflection coil 3 and the capacitor 6.

Horizontal pincushion distortion correction is performed as follows. The resonance time constants of the horizontal deflection coil 3 and the capacitor 6 and the resonance time constant of the diode modulator modulation coil 11 and the capacitor 7 are set to be the same, and a loop of the horizontal deflection coil 3, the capacitor 6, the diode 8 and the S-shaped correction capacitor 10 is formed. A sawtooth wave current having a horizontal period flows in each of the two loops of the modulation coil 11, the diode 9, the capacitor 7, and the S-shaped correction capacitor 10. If the current flowing in the loop on the modulation coil 11 side is reduced, the horizontal deflection coil It is configured so that the current of the loop on the third side increases. And
The parabolic waveform of vertical synchronization is input to the base of the transistor 12 connected to the modulation coil 11 via a resistor to modulate the coil 11. This increases the horizontal deflection current in the middle of the vertical cycle to correct horizontal pincushion distortion. Further, if a direct current is passed through the modulation coil 11, that is, if the direct current component of the base potential of the transistor 12 is made variable, the peak value of the current flowing through the deflection coil 3 can be controlled. This means that the horizontal deflection width is variable on the screen.

As shown in FIG. 8A, when displaying video software having an aspect ratio of 4: 3 on a 16: 9 display surface,
The DC operating point of the base of the transistor 12 is raised, the current flowing through the modulation coil 11 is increased, the current flowing through the horizontal deflection coil 3 is reduced, the horizontal deflection width is reduced, and the vertical and horizontal roundness is maintained. At this time, there are no rasters in the shaded areas around the left and right of the screen of FIG.

When a display as shown in FIG. 8 (a) is displayed on the 16: 9 display surface, the non-image areas (shaded areas) on the left and right of the screen are unsightly and unsightly. It is easier to see if it is displayed on the entire display surface. In order to realize this, the capacity of the S-shaped correction capacitor is increased and the horizontal linearity is changed as shown in FIG.
Both ends are extended as shown in (b). In FIG. 7, the switch 14 is turned on, the additional S-shaped correction capacitor 13 is connected in parallel to the S-shaped correction capacitor 10, and the combined capacitance is increased to switch the linearity. Further, the DC operating point of the transistor 12 is controlled so that the horizontal width is swung to the full 16: 9 display surface.

[0008]

A conventional wide aspect television receiver displays horizontal deflection linearity as one method of displaying video software having an aspect ratio of 4: 3 on a display screen of 16: 9. Although the left and right peripheral portions are extended with respect to the central portion, since the horizontal deflection speed is higher in the peripheral portion than in the central portion, the light output of the CRT becomes less in the peripheral portion than in the horizontal central portion and becomes dark. In order to make the brightness of the CRT uniform in a video display device having an aspect ratio of 4: 3, for example, Japanese Patent Application Laid-Open No. 2-5898.
No. 0, JP-A-2-153680, etc. have been proposed.

The present invention has been made to solve the above problems, and when the display shown in FIG. 8 (b) is performed, the center of the screen is linked with the extension of the linearity of the peripheral portion. Provided is a television receiver configured to reduce a difference in luminance output between a peripheral portion and a peripheral portion.

[0010]

A television receiver according to the present invention has a horizontally long screen whose aspect ratio is larger than 4: 3, and the entire screen is provided with video software having an aspect ratio of 4: 3. Generates a horizontal-cycle parabolic wave in a television receiver equipped with a horizontal deflection circuit that can switch the linearity of horizontal deflection from an appropriate state for display to a state in which the left and right peripheral parts are extended to the center of the screen for deflection. The linearity. The correction waveform generating means, the modulation means for modulating the amplitude of the video signal by the output signal of the correction waveform generating means, and the opening / closing means provided between the correction waveform generating means and the modulating means are provided. The opening / closing means is closed when the state is switched from the proper state to the peripherally extended state.

Further, in a television receiver having a horizontally long screen having an aspect ratio of larger than 4: 3, and displaying video software having an aspect ratio of 4: 3 on the entire screen, the entire screen is displayed. Parabolic waveform synthesizing means for producing a horizontal period parabolic waveform from a pulse from a flyback transformer when displaying video software with an aspect ratio of 4: 3, and modulation for modulating the amplitude of the video signal by the signal from the parabolic waveform synthesizing means. Means, control means for controlling the horizontal deflection circuit by the signal from the parabolic waveform synthesizing means so as to have a horizontal linearity characteristic of extending the peripheral portion with respect to the central portion, the parabolic waveform synthesizing means, the modulating means, and And an opening / closing means provided between the control means and the control means.

Further, at this time, in order to make the parabolic wave a corrected parabolic wave having a flat central portion, a waveform shaping means for clipping the output of the parabolic waveform synthesizing means with a predetermined voltage is provided on the output side of the parabolic wave synthesizing means. Is.

[0013]

The television receiver according to the present invention comprises 16
In the case of displaying 4 to 3 video software on a CRT of 9 to expand the peripheral part to the central part in the horizontal direction and display it on the entire screen, the amplitude of the video signal is simultaneously modulated by the parabola wave of the horizontal cycle, Reduce the difference in light output between the central and peripheral areas of the screen.

[0014]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a CRT, 3 is a horizontal deflection coil,
Reference numeral 17 is a CRT drive circuit for applying a voltage to the cathode of the CRT 1, 18 is an amplitude modulation circuit for amplitude-modulating the video signal of each color, 19 is a color signal demodulation circuit, and 20 is an amplitude modulation circuit 1.
A correction waveform generation circuit for giving a correction waveform to 8 and a high voltage generation / horizontal circuit 21 for switching the horizontal linearity by a high voltage generation circuit as shown in FIG. 7 and a horizontal linearity switching signal (that is, connecting an additional S-shaped correction capacitor). The deflection circuit 23 is a switch for turning on / off the output of the correction waveform generation circuit 20 according to a horizontal linearity switching signal.

Next, the operation will be described. The color signal demodulation circuit 19 demodulates a video signal or a color signal, separates and amplifies into three color signals of R, G, and B. The amplitude modulation circuit 18 is composed of a variable amplifier, and R,
The G and B color signals are amplitude-modulated. The correction waveform generating circuit 20 receives the horizontal synchronizing signal and generates a parabolic waveform with a horizontal period as shown in FIG. 3, and this waveform is applied as a modulating voltage to each amplitude modulating circuit 18 when the switch 23 is closed. It is done like this.

Now, in order to display the video software having the aspect ratio of 4: 3 on the display screen of 16: 9, the switch 14 shown in FIG. 7 is closed by the horizontal linearity switching signal and the horizontal width is controlled to make the horizontal linearity horizontal. When both ends around the direction are extended, the switch 23 is closed by the horizontal linearity switching signal.
In the amplitude modulation circuit 18, the amplitudes of the G and B signals are modulated by the parabolic waveform of the horizontal cycle of the correction waveform generation circuit 20 with reference to the level at which the CRT 1 starts to emit light. For this reason, the brightness is corrected to the same extent as that of the central part at both ends around the CRT 1. Further, when the horizontal linearity switching signal opens the switch 14 in FIG. 7 and the high voltage generation / horizontal deflection circuit 21 operates so as to control the horizontal width and restore the horizontal linearity, the switch 23 is switched by the horizontal linearity switching signal. Opening, the correction waveform generation circuit 20 stops supplying the correction signal to the amplitude modulation circuit 18.

FIG. 2 shows an example in which the luminance signal -Y and the color difference signals RY, BY, GY are extracted from the color signal demodulation circuit, and the luminance correction is performed on the -Y signal by the amplitude. The number of amplitude modulation circuits is reduced by performing modulation.

An example of the circuit of the amplitude modulation circuit 18 shown in FIG. 2 will be shown in FIG. 3 to explain the operation.
The amplitude modulation circuit 18 is composed of a double balance modulation circuit as shown in FIG. A horizontal period parabolic waveform voltage as shown in FIG. 3 is input from the input terminal 30 as a correction waveform for amplitude modulation of the luminance signal. Further, by inputting the -Y signal (negative polarity luminance signal) as shown in FIG. 3 from the input terminal 31, the correction waveform is amplitude-modulated in FIG.
The -Y signal shown in is obtained from the output terminal 32. This circuit is modulated with a correction waveform centered on the V1 voltage which is the black level. By setting the V1 voltage to correspond to the cutoff voltage at the cathode that drives the CRT, the cutoff portion is not modulated and only the signal portion is amplitude-modulated.

Example 2. In the above-described embodiment, the capacitance of the S-shaped correction capacitor is switched to expand the horizontal linearity and the correction waveform is created to match it. However, as shown in FIG. Switching and generation of the amplitude modulation signal of the video signal can be performed.

In FIG. 4, 25 is a parabolic waveform synthesizing circuit, 26 is a waveform shaping circuit, 27 is a linearity changing switch, 28 is an amplifier, and 24 is a saturable reactor. The parabolic waveform synthesis circuit 25 creates a parabolic waveform as shown in FIG. 5A from the flyback pulse output to the winding of the flyback transformer 2. This parabolic waveform is clipped by the waveform shaping circuit 26 and shaped into a pan-shaped corrected parabolic waveform shown in FIG. 5B. This correction waveform is applied to the video signal amplitude modulation circuit 18 through the linearity changing switch 27 and simultaneously applied to the control winding of the saturable reactor 24 through the amplifier 28. Since the saturable reactor 24 is a transformer in which the inductance of the output winding changes according to the current flowing in the control winding as shown in FIG. 6, the peripheral portion where the control current increases as shown in FIG. 5C. The linearity of can be extended. Therefore, when the linearity change switch 27 is closed, the linearity of the peripheral portion is extended as described above, and at the same time, the luminance of the peripheral portion is increased in the amplitude modulation circuit 18, and the entire screen can be automatically adjusted to a uniform luminance. In this case, since the video signal is modulated with the corrected parabolic waveform as described above, most of the screen is kept in proper linearity, and an easy-to-see video can be obtained.

[0021]

As described above, according to the present invention, 16
When an image having an aspect ratio of 4: 3 is displayed on a screen having an aspect ratio of 9, the difference in luminance output between the central portion and the peripheral portion of the CRT screen can be reduced.

Further, since the horizontal linearity is switched and the amplitude modulation signal of the video signal is generated from one correction waveform, both the above-mentioned controls can be operated by one opening / closing means, and the circuit configuration and the switching operation can be simplified. Can be

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a television receiver according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a modification of the first embodiment.

FIG. 3 is a circuit diagram showing an amplitude modulation circuit used in the first embodiment.

FIG. 4 is a circuit diagram showing a main part of a television receiver according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a correction waveform and a screen in the second embodiment.

6 is a diagram showing characteristics of a saturable reactor used in Example 2. FIG.

FIG. 7 is a diagram showing a general high voltage generation / horizontal deflection circuit capable of switching horizontal linearity.

FIG. 8 is a diagram showing a screen and a degree of extension of linearity when the horizontal linearity of an image is switched.

[Explanation of symbols]

1 CRT, 2 flyback transformer, 3 horizontal deflection coil, 4 horizontal linearity correction coil, 5 horizontal output transistor, 6, 7 resonance capacitor, 8, 9 diode, 10 S-shaped correction capacitor, 11 diode modulator modulation coil, 12 diode modulator Output transistor, 13 S-shaped correction capacitor for addition, 14 switch, 17 CRT drive circuit, 18
Amplitude modulation circuit, 19-color demodulation circuit, 20 correction waveform generation circuit, 21 high voltage generation / horizontal deflection circuit, 23 switch, 24 saturable reactor, 25 parabolic waveform synthesis circuit, 26 waveform shaping circuit, 27 switch.

Claims (3)

[Claims] 1. A horizontal screen having an aspect ratio larger than 4: 3 is provided, and in order to display image software having an aspect ratio of 4: 3 on the entire screen, the linearity of horizontal deflection is adjusted from the proper state to the center of the screen. On the other hand, in a television receiver equipped with a horizontal deflection circuit capable of switching the left and right peripheral parts to an extended state, a correction waveform generating means for generating a parabola wave of a horizontal period and an output signal of the correction waveform generating means are used. A modulation means for modulating the amplitude of the video signal and an opening / closing means provided between the correction waveform generating means and the modulating means are provided, and the opening / closing means is closed when the linearity is switched from the proper state to the peripheral extension state. A television receiver characterized by the above. 2. A television receiver having a horizontally long screen whose aspect ratio is larger than 4: 3 and displaying video software having an aspect ratio of 4: 3 on the entire screen. Parabolic waveform synthesizing means for producing a horizontal period parabolic waveform from a pulse from a flyback transformer when displaying video software with an aspect ratio of 4: 3, and modulation for modulating the amplitude of the video signal by the signal from the parabolic waveform synthesizing means. Means, control means for controlling the horizontal deflection circuit by the signal from the parabolic waveform synthesizing means so as to have a horizontal linearity characteristic of extending the peripheral portion with respect to the central portion, the parabolic waveform synthesizing means, the modulating means, and A television receiver comprising: an opening / closing unit provided between the control unit and the control unit. 3. The television receiving apparatus according to claim 2, further comprising waveform shaping means for clipping the output of the parabolic waveform synthesizing means with a predetermined voltage to shape a corrected parabolic waveform having a horizontal period having a flat portion. Machine.