JP2590871B2 - Horizontal circuit of television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial Fields B Overview of the Invention C Prior Art D Problems to be Solved by the Invention E Means for Solving the Problems F Operation G Example G-1 Configuration (FIG. 1) G-2 Operation (FIGS. 1 and 2) H Effect of the Invention A Industrial Field of the Invention The present invention generates a flyback pulse and a horizontal blanking signal synchronized with a horizontal synchronization signal separated from a video signal. The present invention relates to a horizontal circuit of a receiver.

B. SUMMARY OF THE INVENTION The present invention provides a horizontal circuit for a television receiver for generating a flyback pulse and a horizontal blanking signal, each of which is synchronized with a horizontal synchronization signal separated from a video signal. And a rising or falling slope of the sawtooth voltage signal has a width corresponding to a period in which a level between the first and second levels sandwiching the reference level is obtained. Control to form a pulse signal having a horizontal blanking signal, and to match the time when each rising or falling slope of the sawtooth voltage signal takes the above-mentioned reference level with the time at the center of the flyback pulse. And a horizontal drive signal is formed based on the sawtooth wave voltage signal, so that the horizontal synchronizing signal can be obtained in a relatively simple and integrated circuit. A synchronous flyback pulses and the horizontal blanking signal, is obtained to be able to get in a state in which it is possible to set the width of each independently.

C Prior Art In a television receiver, during each retrace period in horizontal and vertical scanning by an electron beam performed in the cathode ray tube, bright lines are prevented from being generated on the screen of the cathode ray tube, and unnecessary Image blanking is performed to erase the image. For such image blanking, a blanking signal corresponding to each blanking period is used. Further, the video signal supplied to such a television receiver has a blanking portion which is a non-video signal portion corresponding to each blanking period.

Usually, a flyback pulse obtained from a horizontal output circuit is used as a horizontal blanking signal which should correspond to each horizontal blanking period, and therefore should correspond to each horizontal blanking section of the video signal. The flyback pulse is generated over the entire horizontal retrace period, and does not directly correspond to the period length of each horizontal blanking portion of the video signal.
The width of the flyback pulse and the period length of each horizontal blanking section of the video signal are designed to be substantially the same in about 11 μsec, for example, with the horizontal frequency set to about 15.75 kHz.

By the way, in a television receiver, for example, a color video signal based on a normal NTSC system in which a vertical frequency is 60 Hz and a horizontal frequency is approximately 15.75 kHz, and a normal NTSC system is used.
Horizontal frequency is 2 compared to SC video signal.
A multi-scan television receiver capable of displaying a color image based on any of the image quality improving color video signals whose horizontal frequency is set to approximately 31.5 kHz. It has been proposed as. In such a multi-scan television receiver, in the horizontal circuit, a frequency corresponding to the horizontal frequency of the input video signal, that is, for example, two types of horizontal frequency signals having frequencies of about 15.75 kHz and about 31.5 kHz are used. It is selectively formed and used for horizontal deflection operation and the like.

As described above, in a multi-scan television receiver that handles a video signal having a horizontal frequency of approximately 31.5 kHz in addition to a video signal having a horizontal frequency of approximately 15.75 kHz, a flyback pulse obtained from a horizontal output circuit Is designed to substantially match the period length of each horizontal blanking section of a video signal having a horizontal frequency of about 31.5 kHz, and is, for example, about 5 to 6 μsec. Therefore, when displaying an image based on a video signal having a horizontal frequency of approximately 15.75 kHz, the period length of each horizontal blanking section of the video signal is longer than the width of the flyback pulse, and the flyback pulse is When used as a signal, image blanking is not performed corresponding to the entire horizontal blanking portion of the video signal, and various noises appear at the end of the screen of the cathode ray tube.

Therefore, for example, in a multi-scan television receiver or the like that can handle both a video signal having a horizontal frequency of approximately 15.75 kHz and a video signal having a horizontal frequency of approximately 31.5 kHz, In the horizontal circuit, a horizontal blanking signal having a desired time width is formed based on the flyback pulse.

D Problems to be Solved by the Invention However, when a horizontal blanking signal is formed based on a flyback pulse in a horizontal circuit such as a multi-scan television receiver as described above, for example, Based on the flyback pulse obtained from the horizontal output circuit, a parabolic waveform signal synchronized with the flyback pulse is formed, and then the parabolic waveform signal is sliced at a predetermined level to form a horizontal blanking signal. For this reason, the horizontal circuit becomes significantly more complicated than the original one, and the number of circuit components is greatly increased. In addition, the horizontal circuit includes a portion that is not suitable for integration into an integrated circuit. In this case, the configuration including the combination with the external circuit portion is troublesome. In addition, there is a problem associated with these, which leads to an increase in cost and a decrease in circuit performance.

In view of such a point, the present invention provides a television receiver which is relatively simple to obtain a flyback pulse and a horizontal blanking signal each synchronized with a horizontal synchronization signal separated from a video signal. Therefore, the horizontal circuit of the television receiver, in which the width of the flyback pulse and the width of the horizontal blanking signal can be independently set under a configuration that does not cause a decrease in circuit performance, is described. The purpose is to provide.

E Means for Solving the Problems In order to achieve the above-mentioned object, a horizontal circuit of a television receiver according to the present invention comprises a horizontal synchronization separation section for separating a horizontal synchronization signal from a video signal, and a horizontal synchronization separation section. A horizontal oscillator for generating a sawtooth voltage signal having a horizontal frequency synchronized with a horizontal synchronization signal obtained from the horizontal oscillator, a blanking signal generator to which the sawtooth voltage signal is supplied from the horizontal oscillator, and a horizontal oscillator. A drive signal supply unit to which a saw-tooth voltage signal and a flyback pulse from the unit are supplied. Then, the blanking signal forming section determines that each rising or falling slope of the sawtooth voltage signal from the horizontal oscillation section is equal to or lower than a first level higher than the reference level by a predetermined level and is lower than a first level by a predetermined level. A pulse signal having a width corresponding to a period that is equal to or higher than a second level lower than the level by a level, generating a pulse signal obtained under a horizontal frequency, and supplying it as a horizontal blanking signal; Further, the drive signal supply unit controls the time when each rising or falling slope of the sawtooth wave voltage signal from the horizontal oscillation unit takes the reference level and the time at the center of the flyback pulse, and controls the sawtooth. A horizontal drive signal is formed based on the wave voltage signal and supplied to a horizontal output unit that generates a flyback pulse.

F action In the horizontal circuit of the television receiver according to the present invention configured as described above, in the blanking signal forming section, the rising slope section or the falling slope section of the sawtooth voltage signal from the horizontal oscillation section is generated. A comparison is made between the level and a first level that is a predetermined level above the reference level and a second level that is a predetermined level below the reference level, and each rising or falling slope of the sawtooth voltage signal is compared. A horizontal blanking signal having a width corresponding to a period in which the level of the section is equal to or lower than the first level and equal to or higher than the second level is formed. Therefore, the width of the horizontal blanking signal can be adjusted to a desired value independently of the flyback pulse by adjusting the gradient of the slope portion of the sawtooth voltage signal or adjusting the first and second levels. Set to value.

Further, in the drive signal supply unit, the time when each rising slope or each falling slope of the sawtooth voltage signal to be subjected to level comparison in the blanking signal forming unit takes the reference level and the center of the flyback pulse Control is performed to match the time, and a horizontal drive signal is formed based on the sawtooth voltage signal, which is supplied to a horizontal output unit that generates a flyback pulse. Thereby,
The horizontal output section operates according to the horizontal drive signal from the drive signal supply section, and as a result, the flyback pulse is obtained with a width based on the setting in the horizontal output section,
Further, the flyback pulse and the horizontal blanking signal formed in the blanking signal forming section surely have an accurate synchronous relationship.

And in this way, obtained from the horizontal oscillator,
Based on the sawtooth voltage signal synchronized with the horizontal synchronization signal,
The horizontal blanking signal is formed so that the whole circuit is relatively simple and does not increase the number of circuit parts or cost significantly, and has a configuration suitable for integration into an integrated circuit. It is said.

G. Example G-1 Configuration (FIG. 1) FIG. 1 shows an example of a horizontal circuit of a television receiver according to the present invention, together with peripheral circuit portions.

In the example of the circuit shown in FIG.
In addition, a color video signal VD1 based on a normal NTSC system with a horizontal frequency of approximately 15.75 kHz, and a horizontal frequency of approximately 31.5 kHz
The image quality improving color video signal VD2 is selectively supplied. Color video signal from input terminal 11
The VD1 or VD2 is supplied to the video signal processing unit 12, and after being subjected to predetermined processing in the video signal processing unit 12, is derived to the video signal output terminal 13, for example, as an image display signal. Further, a color video signal VD1 or VD2 from the input terminal 11 is also supplied to a horizontal sync separator 14, the horizontal sync separator 14, a horizontal sync signal S _H separated from the color video signal VD1 or VD2 obtained .

Further, in this example, a voltage controlled oscillating unit 15 is provided, and from the voltage controlled oscillating unit 15, a first oscillation output as a sawtooth wave voltage signal Sos and a sawtooth wave voltage signal Sos The second oscillation output is a rectangular wave voltage signal Sop which takes a low level corresponding to each rising slope and takes a high level corresponding to the falling slope. The sawtooth wave voltage signal Sos from the voltage control oscillator 15 is
With the horizontal synchronizing signal S _H obtained from 4 is supplied to a phase comparator unit 16, which in being carried out phase comparison of a sawtooth voltage signal Sos and a horizontal synchronizing signal S _H, the phase comparator
From 16, a comparison output signal Sc is obtained. This comparison output signal Sc
Is supplied to a low-pass filter (LPF) 17, from which a control signal Sx based on the comparison output signal Sc is obtained. The control signal Sx is supplied to the control terminal of the voltage control oscillator 15.
The phase comparator 16 and the LPF 17 arranged as described above form an AFC loop for the voltage controlled oscillator 15, and the sawtooth voltage signal So as the first oscillation output of the voltage controlled oscillator 15.
s and each of the second is an oscillation output square wave voltage signal Sop is, the AFC loop is controlled so as to precisely synchronize with the horizontal synchronizing signal S _H obtained from the horizontal synchronizing separator 14. Then, the voltage controlled oscillator 15, the phase comparator 16, and the LPF 17 form a horizontal oscillator.

The sawtooth voltage signal Sos from the voltage controlled oscillator 15 in the horizontal oscillator is supplied to the negative polarity comparison input terminal of the first level comparator 18 and the positive polarity comparison input of the second level comparator 19. Supplied to the end. A voltage Vo + Va obtained by adding the voltage Va obtained from the first reference voltage source 21 to the voltage Vo obtained from the reference voltage source 20 is supplied to a reference input terminal of the first level comparison unit 18. Second level comparison unit
The voltage Vo obtained from the reference voltage source 20 is applied to the reference input terminal 19.
, A voltage Vo−Vb obtained by subtracting the voltage Vb obtained from the second reference voltage source 22 is supplied. Voltage Va and voltage
Vb is set to, for example, the same level. And
In the first level comparing section 18, the sawtooth voltage signal So
The level comparison between s and the voltage Vo + Va is performed, and a comparison output signal Sa that takes a high level only when the level of the sawtooth voltage signal Sos is equal to or lower than the level of the voltage Vo + Va is obtained at the output terminal. In the second level comparing section 19, the level comparison between the saw-tooth waveform voltage signal Sos and the voltage Vo-Va is performed, and the level of the saw-tooth waveform voltage signal Sos is equal to the voltage Vo-Va at the output terminal. A comparison output signal Sb that takes a high level only when the level is equal to or higher than the level is obtained.

The comparison output signals Sa and Sb obtained from the first and second level comparison units 18 and 19 are supplied to the AND circuit unit 23 together with the rectangular wave voltage signal Sop from the voltage control oscillation unit 15 in the horizontal oscillation unit. From the AND circuit unit 23, a pulse signal formed only when all of the comparison output signals Sa and Sb and the rectangular wave voltage signal Sop take a high level is obtained,
This is led out to the output terminal 24 as the horizontal blanking signal Sbk. Thus, the first and second level comparing units 18 and 19, the reference voltage source 20, the first and second reference voltage sources 21
And 22, and the AND circuit section 23 constitute a horizontal blanking signal forming section.

The sawtooth voltage signal Sos from the voltage controlled oscillator 15 in the horizontal oscillator is supplied to one input terminal of the phase comparator 25 and the phase shifter 26, respectively. The flyback pulse Sf obtained from the horizontal output unit 27 is supplied to the other input terminal of the phase comparison unit 25, and the voltage Vo obtained from the reference voltage source 20 is supplied to the control terminal of the phase comparison unit 25. Is done.
In the phase comparator 25, the sawtooth voltage signal Sos
Phase comparison is performed between a point having a level equal to o and the center of the flyback pulse Sf, and a comparison output signal Sd corresponding to the phase difference between the two is obtained from the phase comparison unit 25. This comparison output signal Sd is supplied to a low-pass filter (LPF) 2
8, and a control signal Sy based on the comparison output signal Sd is obtained from the LPF. The control signal Sy is supplied to a control end of the phase shift unit 26, and the phase of the sawtooth wave voltage signal Sos is changed according to the control signal Sy in the phase shift unit 26, and the sawtooth wave voltage signal Sos is changed to the voltage Vo. Is controlled so that the point at which the level is equal to the center of the flyback pulse Sf is matched.

In this way, the point where the sawtooth wave voltage signal Sos takes a level equal to the voltage Vo and the state in which the center of the flyback pulse Sf coincides are maintained, and thus the signal is obtained from the phase shift unit 26. Phase-controlled sawtooth voltage signal So
s' is supplied to the drive signal forming unit 29, and the drive signal forming unit 29
Thereafter, a horizontal drive signal Sh is formed based on the phase-controlled sawtooth voltage signal Sos', and is supplied to the drive unit 30. Therefore, the above-described phase comparison section 25, phase shift section 26, LPF 28
In addition, a drive signal supply unit is formed by the entire drive signal formation unit 29.

The drive unit 30 drives the horizontal output unit 27 in accordance with the horizontal drive signal Sh, and performs a horizontal deflection operation. The horizontal output unit 27 includes a horizontal output transistor 31 connected to the drive unit 30, a damper diode 32 connected to the collector of the horizontal output transistor 31, a charge / discharge capacitor 33, and a horizontal deflection coil unit 34.
And a power supply voltage Vc from a power supply terminal 36 through the choke coil 35.
c is supplied. Then, a horizontal deflection current having a sawtooth waveform is applied to the horizontal deflection coil unit 34, and the flyback pulse Sf is applied to the collector of the horizontal output transistor 31.
Is obtained, which is the phase comparison unit in the drive signal supply unit.
Supplied to 25.

The horizontal circuit according to the present invention formed as described above has a relatively simple configuration, requires a relatively small number of circuit components, and is suitable for integration into an integrated circuit.

G-2 Operation (FIGS. 1 and 2) Under such a configuration, a horizontal frequency of approximately 1
When the color video signal VD1 to 5.75kHz is supplied from the horizontal sync separator 14, horizontal sync signal S _H to the frequency substantially 15.75kHz is obtained. Then, the phase comparison unit 16 and
The AFC loop formed including the LPF 17 causes a saw-tooth voltage signal Sos, which is the first oscillation output of the voltage controlled oscillator 15 to be output.
Each of the square wave voltage signal Sop and the second oscillation output has a frequency of about 15.75 kHz, and the horizontal synchronization signal S _H
And are obtained as shown in FIGS. 2A and 2B. The square wave voltage signal Sop is a sawtooth wave voltage signal S
It takes a low level corresponding to each rising slope of os and a high level corresponding to each falling slope of the sawtooth voltage signal Sos.

Then, the sawtooth voltage signal So from the voltage control oscillator 15
s is supplied from the first level comparing section 18 to generate a sawtooth voltage signal So as shown in FIG. 2C.
It takes a high level during the period when the level of s is lower than the level of the voltage Vo + Va, and the level of the sawtooth voltage signal Sos becomes the voltage Vo + V
It is obtained by taking the low level in the period exceeding the level of a. Also, as shown in FIG. 2D, the level of the sawtooth voltage signal Sos is changed to the voltage Vo-Vb from the second level comparing section 19 to which the sawtooth voltage signal Sos is supplied. And a low level during a period when the level of the sawtooth voltage signal Sos is lower than the level of the voltage Vo-Vb. Further, the horizontal blanking signal Sbk derived from the AND circuit unit 23 to the output terminal 24 to which the comparison output signals Sa and Sb and the rectangular wave voltage signal Sop from the voltage control oscillator 15 are supplied, respectively, As shown in FIG. E, a period during which both the comparison output signals Sa and Sb and the rectangular wave voltage signal Sop are at a high level, that is, when the falling slope of the sawtooth wave voltage signal Sos is equal to or lower than the voltage Vo + Va level In addition, a pulse signal having a frequency corresponding to approximately 15.75 kHz and having a width corresponding to a period in which the level is equal to or higher than the voltage Vo-Vb is obtained.

Therefore, in this case, the width of the horizontal blanking signal Sbk can be arbitrarily set by selecting the gradient of each falling slope of the sawtooth voltage signal Sos and the respective levels of the voltage Vo + Va and the voltage Vo−Vb. Becomes

Further, at this time, the drive signal including the phase comparison unit 25, the phase shift unit 26, and the like to which the sawtooth voltage signal Sos from the voltage control oscillator 15 and the flyback pulse Sf obtained from the horizontal output unit 27 are supplied. In the supply unit, control is performed to match the point of the sawtooth wave voltage signal Sos at a level equal to the voltage Vo in each falling slope and the center of the flyback pulse Sf, and as a result, the flyback pulse Sf But the second
As shown in FIG. F, the frequency is obtained to be approximately 15.75 kHz synchronized with the horizontal blanking signal Sbk.

Then, when the color video signal VD2 to substantially 31.5kHz horizontal frequency to the input terminal 11 is supplied from the horizontal sync separator 14, horizontal sync signal S _H to the frequency substantially 31.5kHz is obtained. Then, the first AFC loop of the voltage controlled oscillator 15 is formed by the AFC loop formed including the phase comparator 16 and the LPF 17.
Of an oscillation output respective sawtooth wave voltage signal Sos and second square wave voltage signal Sop an oscillation output whose frequency is substantially 31.5 kHz, is as synchronized with the horizontal synchronizing signal S _H, As shown in FIGS. 2G and 2H, the sawtooth voltage signal Sos and the rectangular voltage signal S shown in FIGS.
It is obtained with a period of 1/2 compared to op. Also in this case, the rectangular wave voltage signal Sop takes a low level corresponding to each rising slope of the sawtooth voltage signal Sos, and the sawtooth voltage signal
High level corresponding to each descending slope of Sos.

Then, a comparison output signal is output from the first level comparison unit 18.
Sa is a sawtooth voltage signal Sos, as shown in FIG.
Takes a high level during a period when the level of the sawtooth wave voltage signal Sos is equal to or lower than the level of the voltage Vo + Va.
, And the comparison output signal Sb is output from the second level comparison unit 19 as shown in FIG.
When the level of s is higher than the level of the voltage Vo-Vb, it takes a high level, and the level of the sawtooth wave voltage signal Sos becomes the voltage Vo-V
A low level is obtained during a period in which the level is lower than the level b. Further, at this time, as shown in FIG. 2K, the horizontal blanking signal Sbk derived from the AND circuit unit 23 to the output terminal 24 has both the comparison output signals Sa and Sb and the rectangular wave voltage signal Sop. During the high level period, ie, when each falling slope of the sawtooth voltage signal Sos is equal to the voltage Vo + Va
And a pulse signal having a frequency corresponding to about 31.5 KHz having a width corresponding to a period in which the level is equal to or lower than the level of the voltage Vo-Vb and higher.

Therefore, also in this case, the width of the horizontal blanking signal Sbk is arbitrarily set by selecting the slope of each falling slope of the sawtooth voltage signal Sos and the respective levels of the voltages Vo + Va and Vo−Vb. You can do it.

Further, at this time, in the drive signal supply unit including the phase comparison unit 25, the phase shift unit 26, and the like, a point where the sawtooth wave voltage signal Sos takes a level equal to the voltage Vo in each falling slope and the center of the flyback pulse Sf The control is performed to make the parts coincide with each other, and as a result, the flyback pulse Sf
As shown in (1), the frequency is approximately 31.5 kHz synchronized with the horizontal blanking signal Sbk.

When the input terminal 11 is supplied with the color video signal VD1 having a horizontal frequency of approximately 15.75 kHz, and when the horizontal frequency is approximately 3
In any case where the color video signal VD2 of 1.5 kHz is supplied, by changing the level of the voltage Vo of the reference voltage source 20, the horizontal blanking signal Sbk and the flyback pulse Sf for the sawtooth wave voltage signal Sos are changed. Can be changed.

H Advantageous Effects of the Invention As is clear from the above description, according to the horizontal circuit of the television receiver according to the present invention, each of the television receivers is synchronized with the horizontal synchronization signal separated from the video signal. In order to obtain the flyback pulse and the horizontal blanking signal, the flyback pulse and the horizontal blanking signal are relatively simple, and the number of circuit components and the cost are not increased. Each width of the horizontal blanking signal can be set independently, and the flyback pulse and the horizontal blanking signal can be accurately synchronized. Thus, for example, a television receiver
Multiple images with different horizontal frequencies, such as a color video signal based on a normal NTSC system with a horizontal frequency of approximately 15.75 kHz and a color video signal for improving image quality with a horizontal frequency of approximately 31.5 kHz Even in the case of a multi-scan television receiver that handles signals, an appropriate horizontal blanking signal can be reliably obtained according to each of a plurality of video signals.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a horizontal circuit of a television receiver according to the present invention, and FIGS. 2A to 2L are waveform diagrams used to explain the operation of the example shown in FIG. In the figure, 11 is an input terminal, 14 is a horizontal sync separator, 15 is a voltage controlled oscillator, 16 and 25 are phase comparators, 17 and 28 are low-pass filters, 18 is a first level comparator, 19 is A second level comparison unit, 20 is a reference voltage source, 21 is a first reference voltage source, 22 is a second reference voltage source, 23 is an AND circuit unit, 24 is an output terminal,
26 is a phase shift unit, 27 is a horizontal output unit, and 29 is a drive signal forming unit.

Claims (1)

(57) [Claims] A horizontal synchronizing separator for separating a horizontal synchronizing signal from a video signal; and a horizontal oscillator for generating a sawtooth voltage signal having a horizontal frequency synchronized with the horizontal synchronizing signal obtained from the horizontal synchronizing separator. The rising or falling slope of the sawtooth voltage signal from the horizontal oscillator is not higher than a first level higher than a reference level by a predetermined level and is higher than a second level lower than the reference level by a predetermined level; A blanking signal forming section having a width corresponding to a certain level, generating a pulse signal obtained under a horizontal frequency, and supplying the pulse signal as a horizontal blanking signal; The sawtooth voltage signal and the flyback pulse are supplied from the CPU and the rising and falling slopes of the sawtooth voltage signal take the reference level and the flyback time. Control to match the time at the center of the clock pulse, forming a horizontal drive signal based on the sawtooth voltage signal, and supplying the horizontal drive signal to a horizontal output unit that generates the flyback pulse A signal supply unit; and a horizontal circuit of a television receiver including: