JP2711142B2 - Time expansion circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time extension circuit of a receiver for reproducing a time-compressed MUSE signal transmitted on a transmission side into an original Hi-Vision signal.

[Conventional technology]

The MUSE signal has a different horizontal blanking rate from the HDTV baseband signal, and can transmit only about 11/12 of the video signal of the baseband signal in one horizontal period. Therefore, in the MUSE system, the video signal of one horizontal period is time-compressed to 11/12 on the transmitting side and time-expanded to 12/11 on the receiving side, so that the video signal with the same amount of information as the baseband signal can be monitored on the HDTV monitor. It has been proposed to project in At this time, as a method of extending the time on the receiver side, it is conceivable to respond by switching the horizontal deflection width of the display.

 FIG. 4 shows an example of this general configuration.

1 is an input terminal of a MUSE signal, 2 is an A / D converter for converting an analog signal arriving at the input terminal 1 into a digital signal,
Reference numeral 9 denotes a synchronizing / timing pulse generating circuit which receives the output of the A / D converter 2 as an input. Reference numeral 3 denotes a MUSE decoding unit which receives the output of the A / D converting unit 2 and the output of the synchronizing / timing pulse generating circuit 9 as inputs. Takes the R signal output of the MUSE decoding unit 3 as input
A D / A converter, 6 is a D / A converter that receives the G signal output of the MUSE decoder 3 as an input, 7 is a D / A converter that receives the B signal output of the MUSE decoder 3, and 8 is a D / A converter. A video circuit which receives the outputs of the A-converters 5, 6, and 7 as an input, 10 is a synchronization circuit which receives an output of a synchronization / timing pulse generation circuit 9 as an input, and 11 is a synchronization circuit 10
A deflection circuit which receives the output of the video circuit 8 and the output of the synchronization / timing pulse generation circuit 9;
This is a high-definition display with 11 outputs as input.

 Next, the operation will be described.

The input terminal 1 receives an analog amount MUSE signal that has been time-compressed in the horizontal direction by 11/12 on the transmitting side. The signal input to the input terminal 1 is converted into a digital signal by the A / D converter 2. The output of the A / D conversion unit 2 is input to the synchronization / timing pulse generation circuit 9, and a clock and a timing pulse are supplied from the synchronization / timing pulse generation circuit 9 to the MUSE decoding unit 3. The output of the A / D converter 2 is MUSE
It is input to the decoding unit 3. The MUSE decoding unit 3 digitally processes the output of the A / D conversion unit 2 and reproduces it as a digital amount of high-definition signal that has been time-compressed to 11/12 in the horizontal direction, and outputs R, G, and B systems. R of MUSE decoding unit 3
The three outputs G and B are converted into analog signals by the D / A converters 5, 6, and 7, respectively, and are input to the video circuit 8. The video circuit 8 amplifies the outputs of the D / A converters 5 to 7 and sends them to the HDTV display 12. The synchronization / timing pulse generation circuit 9 outputs a synchronization signal to the synchronization circuit 10 and outputs a control circuit (hereinafter, referred to as a MUSE control signal) indicating that the input is a MUSE signal to the deflection circuit 11. The synchronization circuit 10 separates an input into a horizontal synchronization signal and a vertical synchronization signal and sends the input to the deflection circuit 11. The deflection circuit 11 determines whether the input signal of the video circuit 8 is a MUSE signal or a baseband signal from the horizontal / vertical synchronization signal output from the synchronization circuit 10 and the output MUSE determination signal of the synchronization / timing pulse generation circuit 9. The horizontal deflection current is switched accordingly.

FIG. 5 shows a video signal waveform and a horizontal deflection current waveform for each of the baseband signal and the MUSE signal. FIG. 5A shows the case of a baseband signal, and FIG. 5B shows the case of a MUSE signal. In the case of the MUSE signal, the value of the horizontal deflection current is made larger than the value of the baseband signal, so that the horizontal deflection width is widened and the display on the high-definition display 12 is extended in time in the horizontal direction to 12/11.

[Problems to be solved by the invention]

In the conventional time expansion circuit, the method of responding by switching the horizontal deflection width is configured as described above.
The SE determination signal is required, and the deflection circuit needs to switch the horizontal deflection current, which complicates the circuit.
It is necessary to adjust the color misregistration and the like in accordance with each deflection width, and there is a problem that the adjustment becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a time extension circuit that does not require switching of a deflection circuit or a MUSE determination signal.

[Means for solving the problem]

The time decompression circuit according to the present invention comprises: A / D conversion means for converting a MUSE signal obtained by compressing a video signal on the time axis by 11/12 times into a digital amount signal; and an output of the A / D conversion means. A synchronizing / timing pulse generating means for generating a clock and a timing pulse from a signal; and a digital amount required for display from an output signal of the A / D converting means and an output signal of the synchronizing / timing pulse generating means. RGB high-definition signal, 11/12 in the horizontal direction
MUSE decoding means for reproducing a signal that has been time-compressed by a factor of two, and a reproduced RGB signal of this MUSE decoding means for one time in the horizontal direction.
A time axis extending means for extending the time by a factor of 2/11. The time axis extending means comprises three line memories each receiving an output signal of the MUSE decoding means as input, and an output of the synchronization / timing pulse generating means. The signal is counted by counting the number of samples in one predetermined horizontal scanning period, and 1
1st reset every frame period or 1 horizontal period
, A phase comparator having the first horizontal counter and an output of a second horizontal counter described later as inputs, a loop filter integrating the output of the phase comparator, and an output of the loop filter. A feedback loop is formed from a voltage-controlled oscillator as an input, and a second horizontal counter that counts the output signal of the voltage-controlled oscillator by 11/12 times the number of samples set in the first horizontal counter. Clock synchronizing means, and performs writing to the line memory using a clock output from the synchronizing / timing pulse generating means,
The reading from the line memory is performed using a clock output from the clock synchronizing means.

[Action]

In the present invention, the MUSE signal time-compressed in the horizontal direction by the above-described configuration is time-expanded and reproduced in the horizontal direction by digital signal processing, so that the blanking rate of the MUSE signal is changed to another HDTV baseband. Since the signal is the same as the signal, the MUSE determination signal is not required, and it is not necessary to switch the deflection current.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a time expansion circuit according to an embodiment of the present invention. In FIG. 1, reference numerals 1 and 2 are the same as those of the conventional example shown in FIG. Reference numeral 9 denotes a synchronizing / timing pulse generating circuit which receives the output of the A / D converter 2 as an input. Reference numeral 3 denotes a MUSE decoding unit which receives the output of the A / D converting unit 2 and the output of the synchronizing / timing pulse generating circuit 9 as inputs. Is a time expansion circuit to which three outputs of the MUSE decoding unit 3 are input. Reference numeral 5 denotes a D / A converter that receives the R signal output of the time expansion circuit 4 as an input, 6 denotes a D / A converter that receives the G signal output of the time expansion circuit 4, and 7 denotes a B signal output of the time expansion circuit 4. D / A converter with input as 8
Is a video circuit that receives the outputs of the D / A converters 5, 6, and 7 as inputs. Reference numeral 10 denotes a synchronization circuit which receives the output of the synchronization / timing pulse generation circuit 9 as an input, reference numeral 11 denotes a deflection circuit which receives the output of the synchronization circuit 10 as an input, and reference numeral 12 denotes a Hi-Vision which receives the output of the video circuit 8 and the output of the deflection circuit 11 as inputs. It is a display.

 Next, the operation will be described.

The input terminal 1 receives an analog amount MUSE signal that has been time-compressed in the horizontal direction by 11/12 on the transmitting side. The signal input to the input terminal 1 is converted into a digital signal by the A / D converter 2. The output of the A / D conversion unit 2 is input to the synchronization / timing pulse generation circuit 9, and a clock and a timing pulse are supplied from the synchronization / timing pulse generation circuit 9 to the MUSE decoding unit 3. The output of the A / D converter 2 is input to the MUSE decoder 3. The MUSE decoder 3 digitally processes the output of the A / D converter 2 and reproduces it as a digital amount of high-definition signal that has been time-compressed to 11/12 in the horizontal direction, and outputs R, G, and B systems. The output of the MUSE decoding unit 3 is input to the time expansion circuit 4 and time-expanded to 12/11 in the horizontal direction and output.

FIG. 2 shows the configuration of the time expansion circuit 4, in which 13 to 15 are line memories, and 16 is a clock synchronization circuit. The three outputs of R, G, and B of the MUSE decode unit 3 are time-expanded to 12/11 by the line memories 13, 14, and 15, respectively. The control of the memory at this time is performed by the signal of the clock synchronization circuit 16.

Next, the configuration of the clock synchronization circuit is shown in FIG. The clock output from the synchronization / timing pulse generation circuit 9 is horizontally synchronized at the same frequency as the transmission rate of the output data of the MUSE decoding unit 3. The horizontal counter 17 counts the clock of the synchronization / timing pulse generation circuit 9. The horizontal counter 18 counts a clock output from a voltage controlled oscillator (hereinafter, referred to as a VCO) 21. Horizontal counter
The number of samples in one horizontal scanning period is set in advance in 17 and 18, and the set value of the horizontal counter 18 is 11
/ 12 times. The output of the horizontal counter 17 and the output of the horizontal counter 18 are input to a phase comparator 19, and the phases are compared every horizontal scanning period. The output of the phase comparator 19 is integrated by the loop filter 20 and becomes the control voltage of the VCO 21. When the loop of the clock synchronization circuit 16 is stabilized, a clock whose frequency is 11/12 of the clock of the synchronization / timing pulse generation circuit 9 is obtained from the clock horizontally synchronized with the output of the VCO 21. Therefore, a clock output from the synchronization / timing pulse generation circuit 9 is used as a write clock for the line memories 13, 14, and 15, and a reset pulse obtained from the horizontal counter 17 is used for reset. Similarly, line memories 13,1
The clock output from 21 is used as the read clock for 4 and 15, and the reset pulse obtained from the horizontal counter 18 is used for reset. In order to stably perform synchronization, the horizontal counter 17 is reset by a frame pulse output from the synchronization / timing pulse generation circuit 9. Therefore, the output data of the MUSE decoding unit 3 is time-expanded to 12/11 in the horizontal direction because the read clocks 13, 14, and 15 have the frequency of 11/12 of the write clock. The three outputs R, G, and B of the time expansion circuit 4 are D / A converters, respectively.
The signals are converted into analog signals by 5, 6, and 7, and are input to the video circuit 8. The video circuit 8 amplifies the outputs of the D / A converters 5 to 7 and sends them to the high-vision display 12. The synchronization signal output from the synchronization / timing pulse generation circuit 9 is input to the synchronization circuit 10. In the synchronization circuit 10, the horizontal synchronization signal and the vertical synchronization signal are separated and sent to the deflection circuit 11. Deflection circuit
The reference numeral 11 determines a horizontal deflection current and a vertical deflection current from the output of the synchronization circuit 10 and outputs the determined current to the HDTV display 12. The horizontal deflection current output from the deflection circuit 11 is adjusted to the horizontal deflection width of the HDTV baseband signal. The HDTV display 12 displays the output signal of the video circuit 8 in accordance with the output current of the deflection circuit 11.

In the above-described embodiment, as described above, the MUSE signal that has been time-compressed in the horizontal direction is configured to be time-expanded and played back in the horizontal direction by digital signal processing. Therefore, it is not necessary to switch the deflection current, and the adjustment of the color shift and the like of the high definition display can be performed with a constant deflection width.

〔The invention's effect〕

As described above, according to the time decompression circuit according to the present invention, A / D conversion means for converting a MUSE signal obtained by compressing a video signal on the time axis by 11/12 times into a digital amount signal, A synchronizing / timing pulse generating means for generating a clock and a timing pulse from an output signal of the A / D converting means; and an output signal of the A / D converting means and the synchronizing / timing pulse.
MUSE decoding means for reproducing a digital amount of RGB Hi-Vision signal which is necessary for display from an output signal of the timing pulse generating means, and which is time-compressed by 11/12 times in the horizontal direction; Time axis extending means for time-expanding the reproduction RGB signal of the MUSE decoding means by a factor of 12/11 in the horizontal direction. The time axis extending means comprises three line memories each receiving the output signal of the MUSE decoding means as an input. A first horizontal counter that counts the number of samples of the output signal of the synchronization / timing pulse generating means in a predetermined one horizontal scanning period and is reset every one frame period or one horizontal period; A phase comparator which receives the input of the first horizontal counter and an output of a second horizontal counter to be described later, a loop filter for integrating the output of the phase comparator, And a second horizontal counter which counts the output signal of the voltage controlled oscillator by 11/12 times the number of samples set in the first horizontal counter. Clock synchronizing means constituting a feedback loop, wherein writing to the line memory is performed using a clock output from the synchronizing / timing pulse generating means, and reading from the line memory is performed by the clock synchronizing means. Since it is configured to use the clock to be output, the MUSE signal time-compressed in the horizontal direction can be time-expanded and reproduced in the horizontal direction by digital signal processing. Therefore, the deflection current is switched by the MUSE determination signal. This eliminates the need for a simpler circuit configuration and adjusts the color shift of the HDTV display. There is an effect that it can be easily performed with a constant deflection width.

[Brief description of the drawings]

FIG. 1 is a block diagram of a time extension circuit according to an embodiment of the present invention, FIG. 2 is a block diagram showing a detailed configuration of the time extension circuit of FIG. 1, and FIG. 3 is a block diagram of the clock synchronization circuit of FIG. FIG. 4 is a block diagram showing the configuration, FIG. 4 is a block diagram of a conventional time expansion circuit, and FIG. 5 is a diagram showing a comparison of a horizontal deflection current between a baseband signal and a MUSE signal in the conventional time expansion circuit. In the figure, 1 is an input terminal of a MUSE signal, 2 is an A / D converter, 3 is a MUSE decoder, 4 is a time decompression circuit, 5, 6, and 7 are D
/ A conversion unit, 8 is a video circuit, 9 is a synchronization / timing pulse generation circuit, 10 is a synchronization circuit, 11 is a deflection circuit, 12 is a high-definition display, 13, 14, and 15 are line memories, 16 is a clock synchronization circuit, 19 , 20 is a horizontal counter, 21 is a phase comparator, 22 is a loop filter, and 23 is a VCO. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A MUSE signal obtained by compressing a video signal by 11/12 times with respect to the time axis to a digital signal.
A / D conversion means, synchronization / timing pulse generation means for generating a clock and a timing pulse from the output signal of the A / D conversion means, and output signals of the A / D conversion means and the synchronization / timing pulse generation means MUSE decoding means for reproducing a digital amount of RGB Hi-Vision signal which is necessary for display from the output signal and which is time-compressed 11/12 times in the horizontal direction; and reproduction of the MUSE decoding means. 12/11 RGB signal horizontally
Time axis extending means for extending the time by a factor of two. The time axis extending means comprises three line memories each receiving an output signal of the MUSE decoding means as input, and an output signal of the synchronization / timing pulse generating means. A first horizontal counter which counts the number of samples in one predetermined horizontal scanning period and is reset every frame period or one horizontal period, and outputs of the first horizontal counter and a second horizontal counter described later. , A loop filter that integrates the output of the phase comparator, a voltage-controlled oscillator that receives the output of the loop filter as an input, and an output signal of the voltage-controlled oscillator. A feedback loop is constituted by a second horizontal counter that counts 11/12 times the number of samples set in the horizontal counter. Writing to the line memory using a clock output from the synchronization / timing pulse generation means, and reading from the line memory using a clock output from the clock synchronization means. A time expansion circuit characterized in that the time expansion circuit is configured to perform the operation.