JPH0758974A - Television receiver - Google Patents

Abstract

PURPOSE:To set a screen so that a picture is easy to see by controlling horizontal amplitude and vertical amplitude and removing a non-picture part or making the non-picture part to be small. CONSTITUTION:A synchronizing separation circuit 5 separates horizontal/vertical synchronizing signals from a video signal and outputs them to a horizontal deflection circuit 11 and a vertical deflection circuit 12. The horizontal deflection circuit 11 is given with the horizontal synchronizing signal, and it generates a sawtooth-like wave and gives it to a deflection coil 9. An S-shape correction switching means 13 changes over S-shape correction quantity. Thus, distortion is controlled and a screen can be displayed on the whole area of a horizontal direction. Then, a vertical amplitude switching means 14 controls the aspect ratio of the screen by changing over vertical amplitude. Thus, the picture whose aspect ratio is 4:3 can be displayed on the whole screen whose aspect ratio is 16:9 while the distortion of the screen is suppressed.

Description

Detailed Description of the Invention

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a wide picture tube.

[0002]

2. Description of the Related Art Currently, NTSC is used for terrestrial broadcasting in Japan.
The method is adopted. This NTSC television broadcast has a screen aspect ratio of 4: 3, and even a television receiver has a CRT with an aspect ratio of 4: 3.
(Picture tube) is used.

FIG. 7 is a block diagram showing a television receiver of the current NTSC system.

A television radio frequency (RF) signal having an aspect ratio of 4: 3 is input to the input terminal 1. The tuner 2 selects a signal of a predetermined channel from the input RF signal,
It is converted to an intermediate frequency (IF) signal and output to the IF / detection circuit 3. The IF / detection circuit 3 amplifies the IF signal and then detects it, and supplies the baseband video signal to the video amplification circuit 4 and the sync separation circuit 5. The video amplifier circuit 4 amplifies the video signal and supplies it to the cathode of the CRT 8.

On the other hand, the sync separation circuit 5 separates the horizontal and vertical sync signals from the video signal and supplies them to the horizontal deflection circuit 6 and the vertical deflection circuit 7, respectively. The horizontal deflection circuit 6 and the vertical deflection circuit 7 respectively apply a sawtooth wave having a horizontal period or a vertical period to the deflection coil 9 to control the deflection of the CRT 8. This allows
The beam current corresponding to the video signal from the video amplifier circuit 4 is deflected, and a television image is displayed on the display screen of the CRT 8.

By the way, in recent years, a high-definition test broadcast by a broadcasting satellite has started, and a high-definition television receiver capable of receiving this test broadcast has been commercialized. In a television receiver capable of receiving such a high-definition television broadcast, a current standard television receiver and a CRT are used.
The aspect ratio is different and the screen is widened. That is, a CRT having a horizontal aspect ratio of 16: 9 is adopted as compared with the CRT of the current television receiver.
Even in this high-definition television receiver, the current NTSC
It is desired to be able to receive the television broadcast of the system. However, since the CRT and the television signal have different aspect ratios, it is not possible to display an image on the entire screen without distortion.

FIG. 8 shows an example in which a current television image having an aspect ratio of 4: 3 is displayed on a screen having an aspect ratio of 16: 9. When an image is displayed without distortion, the CRT is widened, and as shown in FIG. 8, a non-image portion (hatched portion) where an image is not displayed appears in the horizontal direction of the screen. That is, in this case, the current television signal is compressed and displayed in the center of the horizontal scanning period.

This non-image part is annoying to the viewer. Therefore, it is conceivable to increase the horizontal amplitude of the image to display it on the entire screen, but in this case, the image receiving screen becomes laterally stretched, which is also difficult to see. Note that if the vertical amplitude is increased in accordance with the horizontal amplitude, lateral expansion does not occur, but the top and bottom of the screen are chipped.

[0009]

As described above, in the above-described conventional television receiver, the CR having a laterally longer aspect ratio than the aspect ratio of the received television signal is used.
If T is adopted, a non-image portion is displayed in the left-right direction of the screen or the image receiving screen is displayed in a laterally stretched state, which is very difficult to see.

The present invention has been made in view of the above problems, and makes it easy to see the screen by controlling the horizontal amplitude and the vertical amplitude to remove the non-picture area or reduce the non-picture area. It is an object of the present invention to provide a television receiver capable of operating.

[Constitution of Invention]

A television receiver according to the present invention has an S-shaped correction capacitor connected in series with a horizontal deflection coil, generates a horizontal deflection current, and supplies the horizontal deflection current to the horizontal deflection coil. A horizontal deflection circuit for controlling the horizontal deflection of the screen, a vertical deflection circuit for generating a vertical deflection current from a sawtooth wave voltage of a vertical cycle and giving it to the vertical deflection coil to control the vertical deflection of the screen, and the S-shaped correction capacitor The S-shaped correction control means for changing the capacitance and the vertical amplitude control means for changing the vertical deflection current amplitude corresponding to the capacitance of the S-shaped correction capacitor are provided.

[0012]

In the present invention, the S-shaped correction control means changes the capacity of the S-shaped correction capacitor. For example, when the capacity of the S-shaped correction capacitor is made larger than usual, the amplitude of the horizontal deflection current from the horizontal deflection circuit becomes large and the S-shaped curve becomes flat. Then, even when an image is displayed on a display screen having an aspect ratio that is longer than the aspect ratio of the image signal, the horizontal amplitude of the screen becomes large without relatively increasing the distortion. Further, since the vertical amplitude control means changes the amplitude of the vertical deflection current in accordance with the control of the horizontal amplitude, the screen distortion is further suppressed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a television receiver according to the present invention.

A high frequency television signal having an aspect ratio of 4: 3 is input to the input terminal 1. This RF signal is supplied to the tuner 2. The tuner 2 selects a predetermined channel from the RF signal, converts it into an IF signal, and outputs it to the IF / detection circuit 3. The IF / detection circuit 3 amplifies and demodulates the IF signal, and supplies the baseband video signal to the sync separation circuit 5 and the video amplification circuit 4. The video amplifier circuit 4 amplifies the video signal and supplies it to the cathode of the CRT 8.

The sync separation circuit 5 separates the horizontal and vertical sync signals from the video signal and outputs them to the horizontal deflection circuit 11 and the vertical deflection circuit 12, respectively. A horizontal synchronizing signal is applied to the horizontal deflection circuit 11 to generate a sawtooth wave having a horizontal period and apply it to the deflection coil 9. The deflection coil 9 is composed of a horizontal deflection coil L1 and a vertical deflection coil. In the present embodiment, the horizontal deflection circuit 11 is configured so that the S-shaped correction amount can be switched by the S-shaped correction switching means 13.

FIG. 2 is a circuit diagram showing a concrete configuration of the horizontal deflection circuit 11 and the S-shaped correction switching means 13 in FIG.

The horizontal drive pulse input via the terminal 15 is supplied to the base of the horizontal output transistor Q1. The collector of the horizontal output transistor Q1 is connected to the power supply terminal 16 via the primary winding of the flyback transformer T to supply the power supply voltage, and the emitter is connected to the reference potential point. A damper diode D1 and a resonance capacitor C1 are connected in parallel between the collector and the emitter of the transistor Q1. Further, a horizontal deflection coil L1 and an S-shaped correction switching means 13 are connected between the collector and the emitter of the horizontal output transistor Q1.

The S-shaped correction switching means 13 is a horizontal deflection coil L.
S-shaped correction capacitors C2, C3 connected to one end of 1,
C4 and relays RY1, RY2, R connected between the capacitors C2, C3, C4 and the reference potential point, respectively.
It is composed of Y3 and a relay drive circuit 17.
Any one of the relays RY1, RY2 and RY3 is turned on by the relay drive circuit 17.

A horizontal cycle pulse is supplied to the base of the horizontal output transistor Q1, and a horizontal cycle sawtooth wave current flows through the horizontal deflection coil L1. As a result, a parabola voltage is generated in any of the S-shaped correction capacitors C1 to C3. Due to this parabolic voltage, the sawtooth current is S
It is modulated into a letter shape. By this S-shaped correction, the linearity between the central portion and the left and right end portions on the CRT screen is improved.

By the way, in order to change the correction amount of the S-shaped correction, the capacitance of the S-shaped correction capacitor may be changed to change the parabola voltage amplitude. In this case, the S-corrected horizontal deflection current changes as the parabolic voltage changes. For example, if the capacitance of the S-shaped correction capacitor is increased and the parabola voltage amplitude is decreased, the horizontal deflection current increases in amplitude and, compared with the change in the slope of the part corresponding to the center of the screen, the horizontal deflection current of the part corresponding to both ends of the screen increases. The change in slope is small. That is, in this case, the horizontal amplitude can be increased and the lateral extension can be suppressed in the central portion on the CRT screen more than in the left and right end portions.

On the other hand, the vertical deflection circuit 12 is supplied with a vertical synchronizing signal and generates a sawtooth wave having a vertical cycle and outputs it to the deflection coil 9. The vertical deflection circuit 12 of this embodiment switches the amplitude of the sawtooth wave generated by the vertical amplitude switching means 14.

FIG. 4 is a circuit diagram showing a concrete configuration of the vertical deflection circuit 12 and the vertical amplitude switching means 14 in FIG.

Transistors Q2 and Q forming a constant current source
The emitter of 3 is connected to the power supply terminal 22, and the bases are commonly connected. The collector of the transistor Q2 is connected to the base and also to the vertical amplitude switching means 14. The collector of the transistor Q3 is connected to the reference potential point through the capacitor C5 for generating the sawtooth wave and is also connected to the output terminal 24. A collector-emitter path of a switching transistor Q4 is connected in parallel to both ends of the capacitor C5, and a vertical retrace pulse is supplied to the base of the transistor Q4.

The vertical amplitude switching means 14 includes resistors R1, R2 and R3 connected to the collector of the transistor Q2 and a resistor R.
The switch control circuit 20 includes switches S1, S2, S3 connected between 1, R2, R3 and the reference potential point, respectively. The switch control circuit 20 is a switch S
Turn on any one of 1, S2 and S3.

The transistor Q4 is turned on at the timing of the vertical retrace pulse. During the non-pulse period, the capacitor C5 is charged by the collector current of the transistor Q3 forming the constant current source. The charge stored in the capacitor C5 is discharged through the transistor Q4 during the blanking pulse. Thus, the terminal voltage of the capacitor C5 changes in a sawtooth pattern in the vertical cycle. This vertical sawtooth wave voltage is supplied to a vertical output circuit (not shown) via the terminal 24, and a vertical sawtooth wave current flows through the vertical deflection coil.

The sawtooth voltage appearing at terminal 24 can be controlled by varying the charging current of capacitor C5. The charging current, that is, the collector current of the transistor Q3 is changed by controlling the collector current of the transistor Q2. In this embodiment, by changing the resistance value between the collector of the transistor Q2 and the reference potential point, the collector current of the transistor Q2 is controlled to change the charging current of the capacitor C5.

The video signal from the video amplifier circuit 4 is a CRT 8
The CRT 8 emits an electron beam in accordance with a video signal and deflects it by the deflection coil 9 to project an image on a screen having an aspect ratio of 16: 9.

Next, the operation of the embodiment thus constructed will be described with reference to FIGS. 4 is shown in FIG.
FIG. 5 is an equivalent circuit diagram for explaining the operations of the horizontal deflection circuit 11 and the S-shaped correction switching means 13 therein, and FIG. 5 is a waveform diagram for explaining the circuit operation of FIG. 4. FIG. 6 is an explanatory diagram for explaining the display on the screen of the CRT 8.

An RF signal having an aspect ratio of 4: 3 is input to the tuner 2 and a signal of a predetermined channel is selected.
The tuner 2 converts the selected signal into an IF signal,
The detection circuit 3 amplifies the IF signal, demodulates it, and supplies it to the video amplification circuit 4 and the sync separation circuit 5. The sync separation circuit 5 separates the horizontal sync signal and supplies it to the horizontal deflection circuit 11.

The horizontal deflection circuit 11 and the S-shaped correction switching means 13 shown in FIG. 2 can be explained by the equivalent circuit shown in FIG. The horizontal output transistor Q1 and the damper diode D1 in FIG. 2 are represented by a switch SW. The capacitance of the resonance capacitor C1 is Cr, the inductance of the horizontal deflection coil L1 is Ly, and the capacitance of the S-shaped correction capacitor is Cs. Note that Cs is variable. As described above, when the capacitance Cs is changed, the S-shaped correction amount of the horizontal deflection current changes, and the horizontal amplitude also changes.
This will be described with reference to equations (3).

Now, as shown in FIG. 4, the voltage across the S-shaped correction capacitor is es (t), and the deflection coil current is I.
If y (t), the both-end voltage es (t) and the deflection coil current Iy (t) change as shown in FIGS. 5A and 5B, respectively. That is, it is known that the following equations (1) to (3) are established in the section where the time t in FIG. 5 is 0 ≦ t ≦ Ts / 2.

[0032] That is, as shown in FIG. 5, the deflection coil current Iy (t)
Represents a sine curve centered at time t = 0, and the voltage es (t) across the S-shaped correction capacitor represents a cosine curve. From equation (3), it can be seen that ωs decreases as the capacitance Cs increases, and from equation (2), the voltage es (t) across the S-shaped correction capacitor has less ripple and becomes flat. In this case, the deflection coil current Iy (t) is sin
Since the term is small, the S-shaped correction effect is small and the current value is large even at the timing close to t = ± Ts / 2.

The relay drive circuit 17 includes relays RY1 and RY2.
, RY3 by turning on any one of
Change the capacity of the letter correction capacitor in three steps. As a result, the horizontal amplitude of the screen and the S-shaped correction effect are switched in three stages.

On the other hand, the vertical deflection circuit 12 is supplied with a vertical synchronizing signal to generate a sawtooth wave voltage having a vertical cycle. A sawtooth current based on the sawtooth voltage is applied to the deflection coil 9 to control the vertical deflection of the screen. The vertical deflection circuit 12 turns on any one of the switches S1 to S3 by the switch control circuit 20. As a result, the sawtooth wave voltage is changed in three steps, and the vertical amplitude of the screen is switched in three steps.

The deflection coil 9 is driven by the deflection currents from the horizontal deflection circuit 11 and the vertical deflection circuit 12, and the CRT 8
An image based on the video signal from the video amplifier circuit 4 is displayed on the screen of.

Now, the relay drive circuit 17 causes the relay R
It is assumed that Y1 is turned on and the switch control circuit 20 turns on the switch S1. The relay RY1 selects the capacitor C2 as the S-shaped correction capacitor, and the switch S1 selects the resistor R1. It is assumed that the capacitor C2 is a capacitance that gives a normal horizontal amplitude, and the resistor R1 is a resistance value that gives a normal vertical amplitude. Then, as shown in FIG. 6A, an image with an aspect ratio of 4: 3 is displayed on the screen with an aspect ratio of 16: 9. Because of the difference in aspect ratio,
The left and right edges (hatched areas) of the screen are non-image areas.

Here, the switch control circuit 20 selects the switch S2 connected to the resistor R2, and the relay driving circuit 17 turns on the relay RY2 to select the capacitor C3 having a larger capacity than the capacitor C2. To do. Then, as described above, the amplitude of the horizontal deflection current increases, and the horizontal amplitude of the screen also increases. That is, as shown in FIG. 6C, a screen having an aspect ratio of 4: 3 is displayed in the entire horizontal area of the screen. In addition, in this case, the S-shaped correction curve is flatter than in the normal case, and the lateral extension is closer to the left and right edges of the screen, but the extension rate does not change so much near the center of the screen. However, the resistance R
By selecting R2 having a resistance value smaller than 1, the vertical amplitude of the screen is increased and the aspect ratios near the center of the screen are matched. As a result, an image similar to the original image can be displayed in the center of the screen.

However, at the left and right edges of the screen, the image is slightly stretched laterally. Therefore, it is also possible to adopt the display shown in FIG. 6 (b) in which some non-image parts are left at the left and right ends of the screen. That is, in this case, the relay drive circuit 17 is caused to select the relay RY3, and the capacitor C4 having the intermediate capacitance between the capacitors C2 and C3 is connected to the horizontal deflection coil L1. Further, the switch control circuit 20 selects the resistor R3 which gives a vertical amplitude corresponding to the lateral extension in the central portion of the screen in this case. In this case, although some non-image areas remain at the left and right edges of the screen, it is possible to display an image in which lateral expansion is relatively suppressed at the left and right edges.

As described above, in this embodiment, by switching the horizontal amplitude and the S-shaped correction amount by the S-shaped correction switching means 13, it is possible to suppress the distortion and display the screen in the entire horizontal direction. In addition, the vertical amplitude switching means 14 switches the vertical amplitude to control the aspect ratio of the screen. As a result, while suppressing the distortion of the screen, the aspect ratio of 4: 9 is displayed on the display screen of 16: 9.
The image of 3 can be displayed on the entire screen. Since the non-image areas at both ends of the screen are not displayed, the image becomes much easier to see. In addition, by allowing the non-image portion to some extent, the display can be performed in a state where the screen distortion is further reduced, and the display can be performed according to the viewer's preference.

[0040]

As described above, according to the present invention, it is possible to make the screen easy to see by controlling the horizontal amplitude and the vertical amplitude to remove the non-picture area or reduce the non-picture area. Have an effect.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a specific configuration of a horizontal deflection circuit and S-shaped correction switching means in FIG.

FIG. 3 is a circuit diagram showing a specific configuration of a vertical deflection circuit and vertical amplitude switching means in FIG.

FIG. 4 is an equivalent circuit diagram for explaining the operation of the embodiment.

FIG. 5 is a waveform diagram for explaining the operation of the embodiment.

FIG. 6 is an explanatory diagram for explaining the operation of the embodiment.

FIG. 7 is a block diagram showing a conventional television receiver.

FIG. 8 is an explanatory diagram showing a display when an image with an aspect ratio of 4: 3 is displayed on a screen with an aspect ratio of 16: 9.

[Explanation of symbols]

11 ... Horizontal deflection circuit, 12 ... Vertical deflection circuit, 13 ... S-shaped correction switching means, 14 ... Vertical amplitude switching means

Claims (1)

[Claims] 1. A horizontal deflection circuit having an S-shaped correction capacitor connected in series to a horizontal deflection coil, which generates a horizontal deflection current and supplies it to the horizontal deflection coil to control horizontal deflection of a screen; A vertical deflection circuit that generates a vertical deflection current from a sawtooth voltage and applies it to a vertical deflection coil to control vertical deflection of a screen, an S-shaped correction control unit that changes the capacitance of the S-shaped correction capacitor, and the S-shaped correction circuit. A television receiver, comprising: vertical amplitude control means for changing the vertical deflection current amplitude in accordance with the capacity of the correction capacitor.