JP2000106670A - Color television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display images consisting of 1st and 2nd video signals on a picture tube, without missing information amount at the same time. SOLUTION: In this receiver 1st and 2nd video signals from a video chroma signal processing circuit 3 and a character multiplex signal reception circuit 4 are respectively applied to double speed conversion circuits 301,401, where the video signals are compressed in a time-base direction, a SW1 of a changeover circuit 5 outputs alternately the video signals through switching, so that a 1st and 2nd images are displayed in a compressed size side by side. Furthermore, a vertical amplitude of the video images displayed on a picture tube 7 is switched into a 1st display height and a 2nd display height smaller than the 1st display height, and a display position of the video image in a vertical direction is selected, a microcomputer connects to a vertical amplitude changeover circuit 101, a vertical position control circuit 102. When the vertical amplitude is switched from the 1st display height into the 2nd display height in response to a control signal from the microcomputer, the control circuit 102 controls the vertical display position to be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of projecting, on a picture tube, a first screen based on a general television broadcast signal and a second screen based on a second video signal such as a character multiplex signal. The present invention relates to a color television receiver capable of displaying by switching screen sizes.

[0002]

2. Description of the Related Art In recent years, color television receivers for superimposing and displaying a second signal such as a text multiplex broadcast signal on a general television broadcast signal have been developed and commercialized.
This type of color television receiver is configured as shown in FIG.

In FIG. 6, reference numeral 1 denotes an antenna, and 2 denotes a receiving circuit for receiving a television broadcast wave and extracting a baseband composite video signal. This receiving circuit 2
Are supplied to a video / chroma signal processing circuit 3, a character multiplexed signal receiving circuit 4, and a sync separation circuit 8 at the same time. The video / chroma signal processing circuit 3 demodulates the composite video signal and outputs R (red), G (green), B (blue).
The character multiplexed signal receiving circuit 4 is a circuit for taking out a character multiplexed signal superimposed on a composite video signal and converting it into R, G, B primary color signals. The television video signal from the video / chroma signal processing circuit 3 and the character multiplexed signal from the character multiplexed signal receiving circuit 4 are supplied to a switching circuit 5 by switch means SW1, and one of the signals is selectively switched by the circuit 5. The image is supplied to a picture tube drive circuit 6 and is projected on a picture tube 7. The switching circuit 5 is switched by a control signal from the controller 11. The horizontal synchronization signal and the vertical synchronization signal separated by the synchronization separation circuit 8 are supplied to a horizontal deflection circuit 9 and a vertical deflection circuit 10, respectively.

In the television receiver thus configured, a normal television video signal and a character multiplex signal, which is a second video signal, are alternately switched by a switching circuit 5. Under the control of the controller 11, two types of switching operations are possible. That is, the first case is that the switch of the switching circuit 5 is constantly connected to one of the signal sides, and a screen is displayed based on the signal. In this case, the screen based on the other signal cannot be projected. Secondly, during projection of a screen of a television video signal, a switch is switched only in a picture or a character section of a character multiplex signal to superimpose the character multiplex signal. In this case, although the contents of both signals can be confirmed, there is a disadvantage that the amount of information is lost.

[0005]

As described above, in a conventional color television receiver, a screen such as a character multiplexed signal and a screen of a television video signal are simultaneously projected on a picture tube without loss of information amount. I couldn't.

Therefore, the present invention has been made to solve this problem.
It is an object of the present invention to provide a color television receiver capable of simultaneously displaying a screen based on first and second video signals on a picture tube without loss of information amount.

[0007]

According to the present invention, there is provided a color television having reception means for receiving a television broadcast signal, wherein a video signal received by the reception means can be displayed on a picture tube by switching a screen size. A receiver,
A picture tube drive circuit for supplying the picture signal to the picture tube, a deflecting unit including a horizontal deflection circuit and a vertical deflection circuit for performing horizontal and vertical scanning of the picture tube, and a video image displayed on the picture tube. Vertical amplitude switching means for switching a vertical amplitude between a first display height and a second display height different from the first display height, and a vertical display position of an image displayed on the picture tube. And a microcomputer coupled to the vertical amplitude switching means and the screen position changing means. The vertical amplitude is switched in response to a control signal from the microcomputer, and The amplitude is changed from the first display height to the second
And control means for controlling the screen position to be changeable when the display height is switched to the display height of the color television set.

[0008]

According to the above arrangement, a television picture signal and a character multiplexed signal whose horizontal and vertical amplitudes are set to, for example, 1/2 of those in the normal operation can be simultaneously displayed on the picture tube. Since the vertical deflection operation at this time has a reduced deflection amplitude unlike the normal operation, the vertical screen position can be appropriately moved in consideration of the adverse effect on the phosphor of the picture tube.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings. FIG. 1 is a block diagram showing a color television receiver according to one embodiment of the present invention. In this figure, the same components as those in FIG. 6 are denoted by the same reference numerals. That is, the antenna 1, the receiving circuit 2, and the video
A chroma signal processing circuit 3, a character multiplexed signal receiving circuit 4, which constitutes a second video signal source, a switching circuit 5, a picture tube driving circuit 6, a picture tube 7, a sync separation circuit 8, a horizontal deflection circuit 9, and a vertical deflection circuit 10 These are the same components as those in FIG. 1 is different from the conventional example of FIG. 6 in that double-speed conversion circuits 401 and 301 are provided at the subsequent stage of the character multiplexed signal receiving circuit 4 and the video / chroma signal processing circuit 3, respectively.
And the vertical deflection circuit 10 is provided with a vertical amplitude switching circuit 101 and a vertical screen position control circuit 102.
The vertical amplitude switching circuit 101 and the vertical screen position control circuit 102 are controlled by the controller 11. With respect to the switching circuit 5, two switching means S
The output from the double-speed conversion circuit 401 is supplied to the first input terminal of the switch means SW1, and the double-speed conversion circuit 301 is supplied to the second input terminal of SW1.
And the output from the sliding side terminal of the switch means SW1 is supplied to the first input terminal of the switch means SW2, and the output from the character multiplexed signal receiving circuit 4 is supplied to the second input terminal of the switch means SW2. The output from the video / chroma signal processing circuit 3 is supplied to the third input terminal of SW2, and the output from the sliding side terminal of SW2 is supplied to the picture tube drive circuit 6. The switching means S of the above switching circuit 5
W1 and SW2 are switched and controlled by a control signal from the controller 11.

Next, the operation of the above circuit will be described with reference to FIG. 2 shows the timing of the signal waveforms at various parts of the circuit. FIG. 2a shows the waveforms of the R, G, B output signals of the video / chroma signal processing circuit 3, and a1 in FIG.
2 shows a signal waveform obtained by double-speed conversion by the double-speed conversion circuit 301. 2B shows R, R of the character multiplexed signal receiving circuit 4.
2 shows the waveforms of the G and B output signals, and b1 in FIG. 2 shows the signal waveform obtained by double-converting the signal b by the double-speed conversion circuit 401. FIG. 2C shows a control signal supplied from the controller 11 to the switch means SW1 of the switching circuit 5. The control signal is high (H) level and low (H) every half cycle of one horizontal scanning cycle (1H). L) A signal that repeats a level. Therefore, the switch means SW1 selectively outputs the signals a1 and b1 every (1/2) H by the control signal c,
As shown in FIG. 2d, the signal d passed through SW1 is a signal in which a character multiplexed signal and a television video signal are alternately arranged within one horizontal scanning period. In the above description, a character multiplexed signal is described as an example of the second video signal, but another video signal source may be used instead of the character multiplexed signal receiving circuit 4. Also, e and f in FIG. 2 show the waveforms of the horizontal flyback pulse and the horizontal deflection current in the horizontal deflection circuit 9, and the phase relationship with the picture signal d supplied to the picture tube 7 can be confirmed.

FIG. 3 shows an example of the configuration of the double speed conversion circuit, which is a known circuit. In brief, the R, G, and B signals input from terminals 21, 22, and 23 via capacitors C1, C2, and C3 are clamped using a clamp circuit 27 so as to match the input range of the A / D converter. And input to the A / D converters 24, 25, 26. The clamp circuit 27 includes a power supply E for supplying a clamp voltage, and switches S1, S2, and S3 for supplying the clamp voltage to the R, G, and B signals during a period in which a clamp pulse from the terminal 28 exists. Is done. The A / D converters 24, 25, and 26 convert the R, G, and B signals into digital signals and supply the digital signals to the line memories 29, 30, and 31. The line memories 29, 30, and 31 perform reading at twice the writing speed and double-convert the R, G, and B signals. The line memory is of 2H type,
Writing is performed in the first 1H and reading is performed in the next 1H. The timing generator and the clock generator 3
2 is switched between writing and reading by a write / read (W / R) signal from 2, and the image signal is compressed by setting the clock signal RCK at the time of reading to twice the frequency of the clock signal WCK at the time of writing. Then, the image-compressed signal is represented by D
The signal is converted back to an analog signal by the A / A converter 33, and R, G, B signals double-speed converted to the terminals 34, 35, 36 are obtained. The frequency of the clock signal supplied from the timing generator and clock generator 32 to the D / A converter 33 is twice the frequency of the clock signal supplied to the A / D converters 24, 25, and 26. Timing generator and clock generator 3
2 is supplied with a horizontal synchronization signal subjected to automatic frequency control (AFC) from a horizontal AFC circuit 37, and terminals 38 and 39 are connected to the horizontal AFC circuit 37.
Supplies a horizontal synchronizing signal and an AFC pulse.

Further, in the circuit operation of FIG. 1, if the vertical amplitude is set to half of that in the normal operation by the vertical amplitude switching circuit 101, a picture as shown in FIG. That is, the character multiplexed signal and the television video signal each have a size of 1/4 of the screen area in a normal state, and are simultaneously displayed on the left and right sides. Since the image compression is performed by the digital signal processing circuit in the horizontal direction and the scanning amplitude is reduced in the vertical direction, the number of scanning lines does not change and the image quality does not deteriorate.

However, when the screen is displayed for a long time while the vertical amplitude is reduced as shown in FIG. 4A, the deterioration of the phosphor of the picture tube 7 is caused by the degradation of the pictured portion and the unscanned portion ( (Shaded area in the figure), which may cause a problem that the screen brightness becomes uneven.

For example, if the signal before double-speed conversion is supplied to the picture tube driving circuit 6 by operating the switch means SW2 in the switching circuit 5 in FIG. 1, and the vertical amplitude is restored by the vertical amplitude switching circuit 101 at the same time, On the picture tube 7, an ordinary television video signal or a character multiplex signal can be projected. At this time, the degradation of the luminous efficiency of the phosphor in the portion where the vertical amplitude has been reduced to half may appear as uneven screen luminance.

To eliminate such inconvenience, a vertical screen position control circuit 102 is added as shown in FIG. 1, and the screen position is changed as shown in FIGS. 4B and 4C as necessary. Like that. Various timings for changing the screen position are possible. For example, it is possible to change the position randomly every time the vertical amplitude is reduced, or to change the position gradually while watching the screen. However, all of them depend on the control of the controller 11. Any of the above position controls can be realized by using a microcomputer as the controller 11.

FIG. 5 is a circuit diagram showing an example of the configuration of the vertical deflection circuit 10, vertical amplitude switching circuit 101 and vertical screen position control circuit 102 of FIG.

In FIG. 5, reference numeral 103 denotes a vertical sawtooth wave input terminal, to which a sawtooth wave synchronized with a vertical synchronizing signal is supplied from a sawtooth wave generating circuit (not shown). A terminal 104 is a power supply terminal, and the vertical screen position control circuit 1
02 is supplied with power. The sawtooth signal input to the terminal 103 is supplied to the inverting amplifier Q1 via the input resistor R1. The inverting amplifier Q1 has an operational amplifier configuration. The + input terminal is connected to the reference power supply VREF.
A feedback resistor R2 between the input and output terminals;
And a vertical amplitude switching circuit 101 are connected.

The vertical amplitude switching circuit 101 includes the resistor R2
, A series circuit of a switch SW3 and a resistor R3 is connected in parallel, and the on / off of the switch SW3 is controlled by a controller 1.
1 is controlled by a control signal.
When the switch SW3 is off, the gain G of the inverting amplifier Q1 is represented by the ratio of the input resistance R1 to the feedback resistance R2, and -G = R2 / R1. Here, the switch S of the vertical amplitude switching circuit 101
When W3 is turned on, the amplification factor becomes -G = {R2.R3 / (R2 + R3)} / R1. If R2 = R3 is selected, -G = R2 / 2R1, and the sawtooth wave amplitude is halved.

The output terminal of the inverting amplifier Q1 is connected to the-input terminal of the operational amplifier Q2 at the next stage, and the output terminal of Q2 is connected to the amplifier Q3 at the final stage. The output terminal of the amplifier Q3 is connected to one end of the vertical deflection coil L1 and voltage feedback resistors R4 and R5. The other end of the deflection coil L1 is connected to a coupling capacitor C1 and a current detection resistor R6.
, And to the vertical screen position control circuit 102.

A voltage corresponding to the deflection current detected by the current detection resistor R6 is supplied to a connection point between the voltage feedback resistors R4 and R5 via a capacitor C2 and is fed back to the + input terminal of the operational amplifier Q2. It has become. Thus, the operating potential of the amplifier Q3 is determined, and a sawtooth current equivalent to the input sawtooth signal can be supplied to the deflection coil L1.

Furthermore, if a DC voltage is supplied to one end of the deflection coil L1 in addition to the above circuit configuration, a DC current flows through the deflection coil L1 with a voltage difference from the output potential of the amplifier Q3, and Can be controlled.
A screen position control circuit 102 is provided for this purpose.
This screen position control circuit is described in
No. 971. In brief, the output voltage of the voltage control circuit REG whose voltage value is controlled by the controller 11 is supplied to the bases of a pair of complementary-connected transistors Q4 and Q5 via zener diodes D1 and D2, and push-pull is performed. It has a circuit configuration for supplying a DC voltage to the deflection coil L1 in a form. In the figure, R7 to R10 are resistors. In this circuit,
The transistors Q4 and Q5 are operated as constant current circuits, and the operating currents of these constant current circuits are controlled by a control signal from the controller 11, so that a screen position adjusting current not including a ripple current is supplied to the deflection coil L.
1 to supply.

In the vertical deflection circuit configured as described above, the controller 11 controls the vertical amplitude switching circuit 101.
By performing the on / off operation of the switch SW3 and the control operation of the voltage control device REG of the vertical screen position control circuit 102, the vertical screen amplitude and the vertical screen position can be controlled.

The vertical screen position change control can be performed when the vertical amplitude is reduced. Therefore, when a microcomputer is used as the controller 11, the vertical screen position is changed according to the control state of the vertical amplitude switching circuit 101. Position control can be performed, and user-friendly control can be performed.

[0024]

As described above, according to the present invention, the display position of the screen can be controlled when the vertical amplitude is switched, for example, when two screens are displayed side by side, and the brightness unevenness can be reduced. Occurrence can be prevented.

Also, by using a microcomputer as the controller 11,
Can control not only the vertical screen position control circuit 102 but also the vertical amplitude switching circuit 101 and the switching circuit 5, so that the viewer can easily perform various controls.

[Brief description of the drawings]

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

FIG. 2 is a waveform chart illustrating the operation of FIG.

FIG. 3 is a block diagram showing an example of a double speed conversion circuit of FIG. 1;

FIG. 4 is an explanatory view showing a display example of a picture tube screen of FIG. 1;

FIG. 5 is a circuit diagram showing an example of a vertical deflection circuit, a vertical amplitude switching circuit, and a vertical screen position control circuit of FIG.

FIG. 6 is a block diagram showing a conventional color television receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Antenna 2 ... Receiving circuit 3 ... Video / chroma signal processing circuit 4 ... Character multiplex signal receiving circuit 5 ... Switching circuit 6 ... Picture tube driving circuit 7 ... Picture tube 8 ... Synchronous separation circuit 9 ... Horizontal deflection circuit 10 ... Vertical deflection Circuit 11: controller 101: vertical amplitude switching circuit 102: vertical screen position control circuit 301, 401: double speed conversion circuit

Claims (2)

[Claims] 1. A color television receiver comprising a receiving means for receiving a television broadcast signal, wherein a video signal received by said receiving means can be displayed on a picture tube by switching a screen size, A picture tube drive circuit for supplying a signal to the picture tube; a deflection unit including a horizontal deflection circuit and a vertical deflection circuit for performing horizontal and vertical scanning of the picture tube; and a vertical amplitude of an image displayed on the picture tube. Amplitude switching means capable of switching between a first display height and a second display height different from the first display height, and switching a vertical display position of an image displayed on the picture tube. A possible screen position changing means, and a microcomputer coupled to the vertical amplitude switching means and the screen position changing means, wherein the microcomputer is responsive to a control signal from the microcomputer. Control means for switching the vertical amplitude and controlling the screen position to be changeable when the vertical amplitude is switched from the first display height to the second display height. Color television receiver. 2. A screen having a non-video area vertically adjacent to a video signal area is displayed on the picture tube when the vertical display is switched to the second display height by the vertical amplitude switching means. 2. A color television receiver according to claim 1, wherein: