JPH07115558A - Video reproduction device - Google Patents

Abstract

PURPOSE:To provide the device able to reproduce a high definition television signal whose horizontal deflection frequency is nearly twice that of an NTSC signal and the NTSC signal in which a horizontal deflection circuit and a high voltage generating circuit are used in common. CONSTITUTION:When an NTSC signal is reproduced, a horizontal oscillation circuit 15 oscillates a pulse signal whose frequency is twice that of a horizontal synchronizing signal. A time compression circuit 16 compresses time axis of the NTSC signal by 1/2 and outputs the signal of the same content by two lines. A vertical deflection circuit 18 controls vertical deflection so that two lines of the same content are scanned overlappingly into one line. Thus, the horizontal deflection frequency and the vertical deflection frequency for the reproduction of the NTSC signal and for the reproduction of a high definition television signal are set respectively equal to each other, the horizontal deflection circuit and the high voltage generating circuit for the purpose are made in common to be an integrated circuit 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a horizontal deflection frequency of NT.
A high-definition television signal that is about twice the SC signal, and N
The present invention relates to a video playback device capable of playing back with a TSC signal, and in particular, an object thereof is to provide a video playback device in which a horizontal deflection circuit and a high voltage generation circuit can be shared.

[0002]

2. Description of the Related Art In recent years, broadcasting by a high-definition system or a clear-vision system, which is higher in quality than the NTSC system which is a current standard television signal system, and a program supply by a package medium are being performed. The hi-vision system includes a MUSE system, and the clear-vision system includes a first-generation EDTV system and a second-generation EDTV system.

Hi-vision system, clear-vision system,
FIG. 7 shows the horizontal and vertical deflection frequencies of the three NTSC systems. The vertical deflection frequency is almost the same in all three systems,
The horizontal deflection frequency of the high-definition method and the clear-vision method is about twice that of the NTSC method. A conventional video reproducing apparatus capable of reproducing video signals having different horizontal deflection frequencies is shown in FIG. 8 centering on the deflection / high voltage system.

A horizontal and vertical synchronizing signal is separated from a video signal input to the terminal 1 by a synchronizing signal separating circuit 5, and the horizontal synchronizing signal is supplied to a horizontal oscillating circuit 6 and the vertical synchronizing signal is supplied to a vertical oscillating circuit 7. To be done. The horizontal oscillation circuit 6 generates a horizontal pulse synchronized with the horizontal synchronizing signal, and supplies the horizontal pulse to the horizontal deflection circuit 9 and the high voltage generation circuit 8. On the other hand, the vertical oscillation circuit 7 generates a sawtooth wave synchronized with the vertical synchronization signal and supplies it to the vertical deflection circuit 10.

The high voltage output from the high voltage generation circuit 8 is C
It is supplied to the anode of RT (cathode ray tube) 4. The output of the horizontal deflection circuit 9 is supplied to the horizontal deflection winding of the deflection coil 3,
A horizontal deflection current is applied to the winding. The output of the vertical deflection circuit 10 is supplied to the vertical deflection winding of the deflection coil 3, and a vertical deflection current flows through the winding. The electron beam of the CRT 4 is deflected by the horizontal deflection current and the vertical deflection current flowing in the deflection coil 3.

The cathode or grit of the CRT 4 is supplied with a video signal which has been subjected to predetermined processing by the signal processing circuit 2 and amplified, and the video is reproduced on the tube surface of the CRT 4 by the deflection of the electron beam. The above description is a known basic technique, and thus detailed description thereof is omitted.

As described above, since the horizontal deflection frequencies of the high-definition signal and the clear-vision signal and the NTSC signal are largely different, the apparatus shown in FIG. 8 has a mode (a mode for covering the horizontal deflection frequency of 31.468 to 33.75 kHz). High-definition signal and clear-vision signal modes) and NTSC horizontal deflection frequency 15.734 kHz
Switching operation with the z mode is performed so as to correspond to each signal. The mode switching is performed by the high / low control voltage of the control terminal 11, the horizontal oscillation circuit 6 switches the oscillation frequency, and the horizontal deflection circuit 9 switches the operation for performing the optimum deflection operation in each mode. In the generation circuit, the operation is switched so that a high voltage output that is greatly different in each mode is always stably output.

Although the horizontal and vertical deflection frequencies are slightly different between the high-definition signal and the clear-vision signal,
This difference is within the automatic tracking range in the horizontal oscillating circuit 6 and the vertical oscillating circuit 7, and it is not necessary to switch the mode between the high-definition signal and the clear-vision signal.

[0009]

In an apparatus for reproducing only NTSC signals, the horizontal deflection frequency is 15.734 kHz.
Since it is fixed to, there is no need for mode switching. Therefore, the horizontal deflection circuit and the high voltage generation circuit, which have many common points in terms of the circuit configuration, are made into a common circuit and can be configured as one circuit block (that is, as a horizontal deflection high voltage generation circuit). However, an apparatus that reproduces an NTSC signal, a high-definition signal, and a clear-vision signal requires two operation modes in which the horizontal deflection frequency is about twice different, as described above, and therefore an optimum operation is performed in each of the modes. In order to do so, the horizontal deflection circuit 9 and the high voltage generation circuit 8 must be separated and provided separately. Therefore, the conventional device has a problem in that the number of deflection / high voltage-related parts that handle a voltage much higher than that of the signal processing system is increased, and the cost is significantly increased.

Further, when switching between two operation modes in which the horizontal deflection frequency is approximately doubled, the horizontal deflection circuit 9 is used.
Since the switching frequency handled by each output transistor (which originally handles a large current) of the high voltage generation circuit 8 fluctuates greatly, the output transistor may be heavily loaded. Therefore, in terms of reliability, it is not preferable to operate the horizontal deflection frequency by largely changing it.

The present invention is not limited to NTSC signals,
It is an object of the present invention to provide a video reproducing apparatus that can reduce cost and improve reliability even if it is an apparatus that can also reproduce a high-definition signal and a clear-vision signal.

[0012]

Therefore, in order to solve the above-mentioned problems, the present invention provides reproduction of images of a high-definition television signal whose horizontal deflection frequency is about twice that of an NTSC signal and an NTSC signal. In an image reproducing apparatus for performing on the surface of a cathode ray tube, a pulse having a frequency about twice that of a horizontal synchronizing signal separated from the NTSC signal is oscillated during NTSC signal reproduction, and a high-definition television signal is reproduced during reproduction of a high-definition television signal. Horizontal oscillation circuit that oscillates a pulse synchronized with the horizontal synchronizing signal separated from the signal and supplies the pulse to the horizontal deflection system, and the NTSC signal is halved when the NTSC signal is reproduced.
Time-compressed, and outputs two lines of the same content signal corresponding to the one-line signal before time compression, and outputs a non-time-compressed signal when reproducing a high-definition television signal, and outputs it to the cathode ray tube. Supply time compression circuit and NTSC
During signal reproduction, the vertical deflection of the electron beam is controlled so that the two lines having the same content are scanned so as to overlap one line,
A vertical deflection control device that performs vertical deflection in which an electron beam is scanned line by line during reproduction of a high-definition television signal, and the above-mentioned operation switching between NTSC signal reproduction and high-definition television signal reproduction A video reproducing device provided with a control circuit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the horizontal deflection frequency is doubled to 31.486 kHz (the vertical deflection frequency remains 59.94 Hz) when reproducing an NTSC signal. As a result, the horizontal and vertical deflection frequencies can be made approximately equal when processing all high-definition signals, clear-vision signals, and NTSC signals, and the horizontal deflection circuit and the high-voltage generation circuit, which were conventionally separated, are shared and integrated. It is possible to

FIG. 1 shows an embodiment of the present invention. The same parts as those of the related art are designated by the same reference numerals, and the specific description of the parts will be omitted. The horizontal oscillating circuit 15 has a function of oscillating a horizontal pulse synchronized with a horizontal synchronizing signal similar to the conventional one, and a new function which is phase locked to the horizontal synchronizing signal at the time of reproducing the NTSC signal and has a frequency (31) twice that of the horizontal synchronizing signal. .486 kH
z) and the function of generating a horizontal pulse.

As shown in FIG. 2, the time compression circuit 16 has 1
It consists of line memory. FIG. 3 shows the operation of the one-line memory when reproducing the NTSC signal. In contrast to the write clock (WCK) of the line memory, the read clock (RC
K) is doubled in frequency. A write reset (WRST) and a read reset (RRST) with the timings shown in FIGS. 3B and 3C are applied to the NTSC video signal input of FIG. The write address and read address of the line memory are WRST and RRS, respectively.
When T is applied, it is reset to 0, and the address changes as shown in FIG. 3D (solid line is write address, broken line is read address). As a result, the output of the line memory with respect to the input shown in FIG. 3A becomes a signal that is time-compressed to 1/2 as shown in FIG. 3E, and the signal on the same line before compression is repeated twice ( The same content signal is repeated twice).

The video signal processed by the above-mentioned time compression circuit 16 has a frequency twice that of the horizontal synchronizing signal (31.486k).
Hz) horizontal pulse based on the CRT4,
Since the horizontal deflection frequency is double that in normal NTSC reproduction, double density scanning as shown in FIG. 4 (525 scanning lines per field) is performed. A and a ', b in FIG.
, B ′, c and c ′, ... Are signals having the same contents (signals on the same line before time compression), and if they are left as they are, they will become jagged when displaying diagonal lines, for example. Therefore, a and a ', b and b', c and c ', ...
The vertical deflection is controlled so that the scanning lines of are overlapped with each other.
By this control, the number of scanning lines is 262.5 lines per field, which is the same as in normal NTSC reproduction (however, the horizontal deflection frequency is 31.486 kHz).

The above deflection control is performed by the vertical deflection circuit 18. FIG. 5 shows the circuit configuration of the vertical deflection circuit 18. In FIG. 5, a sawtooth wave 20 (supplied from the vertical oscillation circuit 7) synchronized with the vertical synchronizing signal is supplied to the positive input of the amplifier 21, and a sawtooth wave current is passed through the vertical deflection coil 22 of the deflection coil 3, A normal vertical deflection operation (deflection operation of scanning every line) is performed. A voltage proportional to the sawtooth wave current is generated in the resistor 23 having a small resistance value, and the voltage is supplied to the negative input of the amplifier 21 for current feedback. As a result, the amplitude of the sawtooth wave generated in the resistor 23 becomes substantially the same as that of the incoming sawtooth wave 20.

At the time of reproducing the NTSC signal, the pulse generator 3
A square wave pulse 25 is supplied from 1 through a resistor 24.
This square wave pulse 25 has the timing shown in FIG. 3 (f), and a current in which the square wave pulse 25 is superimposed on the sawtooth wave 20 shown in FIG. 6 (a) flows through the vertical deflection coil 22. An enlarged view of the current is shown in FIG. 6B. Every 2H minutes (where H is the horizontal scanning period after time compression), the change in the current of 1H within 2H is the same as that of the next 1H. Since it is the same as the change in the current (the change from the maximum value to the minimum value of the current within 1H is the same), the two scanning lines a and a ', b and b', c and c having the same signal content. ′, ... Can be overlapped and scanned as one line to be deflected in the vertical direction.

In order to overlap two scanning lines having the same signal content, if the vertical scanning period is 250 lines, for example, the pulse amplitude E of the square wave pulse 25 and the sawtooth wave 2 are used.
The relation between the amplitude VPP of 0 and the resistance values R1 and R2 of the resistors 23 and 24 is set as the following equation. R1 · E / (R1 + R2) = VPP / (2 × 250)

In the above description, the square wave pulse is applied to the negative input of the amplifier 21, but of course the same operation can be obtained by applying the square wave pulse to the positive input. (However, the polarity of the square wave pulse is reversed.)

Next, vertical deflection control means other than the vertical deflection circuit shown in FIG. 5 will be described. In some CRT necks, a velocity modulation coil is provided in addition to the deflection coil. The velocity modulation coil controls the scanning velocity in the horizontal direction by the generated magnetic field to perform velocity modulation to emphasize the edge portion of the image. If a control coil similar to this velocity modulation coil is attached in the direction perpendicular to the velocity modulation coil, the electron beam can be vertically modulated. By passing a square-wave pulse current shown in FIG. 3 (f) in the control coil, it is possible to scan two scanning lines having the same signal on the same line.

As described above, in this embodiment, the horizontal deflection frequency is doubled to 31.486 kHz at the time of reproducing the NTSC signal, so that the horizontal deflection frequency can be set at the time of processing all of the high vision signal, the clear vision signal and the NTSC signal. Since the frequencies can be made substantially equal to each other, it is possible to form a circuit (horizontal deflection high voltage generation circuit 17) in which the horizontal deflection circuit and the high voltage generation circuit, which are conventionally separated, are shared and integrated.

Up to this point, the operation at the time of reproducing the NTSC signal has been described, but at the time of reproducing the high-definition signal or the clear-vision signal, the oscillation frequency of the horizontal pulse generated by the horizontal oscillation circuit 15 is changed to the conventional horizontal synchronizing signal. The same as the frequency of. In the time compression circuit 16, the timing of RCK and RRST of the time compression circuit 16 is
The compression operation is stopped by making the timings of WCK and WRSTS equal to each other. Alternatively, the time compression circuit 16
The output of may be connected to the input of the circuit to be in a through state. In the vertical deflection control, the supply of the square wave pulse 25 is stopped.

Switching of the operation mode in each circuit is performed by
It is performed according to a control signal from the control circuit 19. The control circuit 19 may be one that can automatically detect which type of signal the input signal is, or one that outputs a control signal according to the type of the input signal designated by the user. Further, instead of the control circuit 19, a control terminal 11 similar to the conventional one is used.
May be provided, and the operation mode may be switched by the supplied high / low control voltage.

Although the above-described time compression circuit 16 is described as handling only one system of signals, it is needless to say that it can be applied to three systems of signals such as an RGB signal, a luminance signal and two color difference signals. is there

[0026]

As described above, the video reproducing apparatus of the present invention is
When the NTSC signal is reproduced, the horizontal deflection frequency is doubled to 31.486 kHz without changing the vertical deflection frequency, so that when processing high-definition television signals (high-definition signals, clear-vision signals) and NTSC signals, The horizontal deflection frequency and the vertical deflection frequency can be substantially equal frequencies. Therefore, the present invention has the following effects.

(B) The horizontal deflection circuit and the high voltage generation circuit, which have been conventionally separated, can be commonly used to form an integrated circuit, and the cost can be reduced. (The part newly added in this invention is
The cost is sufficiently lower than the cost of separately providing the horizontal deflection circuit and the high voltage generation circuit. )

(B) Since it is no longer necessary to drastically change the horizontal deflection frequency between the reproduction of the NTSC signal and the reproduction of the high definition television signal, the reliability of the horizontal deflection portion and the high voltage generation portion is improved.

(C) In order to double the horizontal deflection frequency, no circuit such as a scanning line interpolating circuit that causes deterioration in vertical resolution is used, so that the cost can be reduced without lowering the image quality.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration of a time compression circuit according to the embodiment.

FIG. 3 is an operation explanatory diagram of a time compression circuit.

FIG. 4 is a diagram showing a doubled state.

FIG. 5 is a diagram showing a configuration of a vertical deflection circuit according to an embodiment.

FIG. 6 is an operation explanatory diagram of a vertical deflection circuit.

FIG. 7 is a diagram showing a deflection frequency of each input signal.

FIG. 8 is a diagram showing a conventional example.

[Explanation of symbols]

 1 Input Terminal 2 Signal Processing Circuit 3 Deflection Coil 4 Cathode Ray Tube (CRT) 5 Sync Separation Circuit 7 Vertical Oscillation Circuit 15 Horizontal Oscillation Circuit 16 Time Compression Circuit 17 Horizontal Deflection High Voltage Generation Circuit 18 Vertical Deflection Circuit (Vertical Deflection Control Device) 19 Control circuit

Claims (1)

[Claims] 1. An image reproducing apparatus for reproducing an image of a high-definition television signal whose horizontal deflection frequency is about twice that of an NTSC signal and an NTSC signal on a tube surface of a cathode ray tube, at the time of reproducing the NTSC signal, It oscillates a pulse of about twice the frequency of the horizontal sync signal separated from the NTSC signal, and oscillates a pulse synchronized with the horizontal sync signal separated from the high-definition television signal when reproducing the high-definition television signal,
A horizontal oscillation circuit that supplies the pulse to the horizontal deflection system, and when reproducing the NTSC signal, the NTSC signal is time-compressed to 1/2 and a signal of the same content corresponding to one line before time compression is divided into two lines. A time compression circuit that outputs a signal that is not time-compressed when reproducing a high-definition television signal and supplies the signal to the cathode ray tube, and when reproducing an NTSC signal, scans two lines of the same content overlapping one line. As described above, the vertical deflection of the electron beam is controlled so that the vertical deflection in which the electron beam is scanned line by line is performed when reproducing the high-definition television signal, and when the NTSC signal is reproduced and when the high-definition television is reproduced. And a control circuit for performing the above-mentioned operation switching at the time of reproducing a John signal.