JPS63278483A - Pal video signal processor - Google Patents

Abstract

PURPOSE:To reduce the number of parts to be adjusted and that of components, by providing first and second switches which select a video signal delayed or not delayed by first and second delay circuits. CONSTITUTION:The titled device is provided with the first switch 1 which selects the video signal delayed or not delayed by the first delay circuit 41 which delays an inputted video signal by a time corresponding to the phase difference of 180 deg. of a color sub carrier, and the second switch 2 which selects the video signal delayed or not delayed by the second delay circuit 42 which delays the inputted video signal by 1H. And the video signal is not separated to a chrominance signal component and a luminance signal component, and is outputted as it is to the first and second circuits. In such a way, it is possible to reduce the number of the parts to be adjusted and that of the components, and to reduce color flicker with simple constitution and low cost, and also, to prevent the signal from being deteriorated by processing the signal as it is.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a PA suitable for use in video disc players, etc.
The present invention relates to an L video signal processing device.

[Summary of the invention]

In the present invention, by combining a PAL video signal with a signal delayed by a time corresponding to the 180 degree phase difference of the color subcarriers or a signal not delayed and a signal delayed by 1H or a signal not delayed, it is possible to The continuous color subcarriers and the continuous inversion of the RY axis are achieved.

[Conventional technology]

As shown in FIG. 6, the color subcarrier (color burst) of a PAL video signal switches between +135 degrees and 1135 degrees every 1H (horizontal scanning period).

Therefore, for example, on a video disc on which a video signal of 1 frame (625H) is recorded per rotation, when a still image playback name jumps between frames for special playback such as trick play, the color burst signal becomes discontinuous. .

In other words, when jumping in the reverse (REV) direction, the phase of the color burst signal advances by 90 degrees, and forward (FW)
D) If you jump in direction, you will be delayed by 90 degrees.

Therefore, processing is required to make the color burst signal continuous at the time of jump.

In addition, in the case of the PAL system, as shown in Figure 6, the R-Y axis is reversed every 1H, so a correction process is required so that the R-Y axis is correctly reversed (reversals continue correctly) at the time of a jump. It becomes necessary.

FIG. 3 is a block diagram of a conventional device for performing such processing.0 During normal playback, the switch 4 is switched to the contact G side by a control signal inputted from the terminal 25. Therefore, at this time, the video signal inputted from the terminal 21 is outputted from the terminal 22 as it is.

In the jump mode, the switch 4 is switched to the contact H side. Therefore, a video signal processed as follows is output.

A PAL video signal input to a terminal 21 is input to a low-pass filter 5, and a luminance signal component of, for example, 3.degree. 2 MHz or less is separated. The video signal is also input to the bandpass filter 6, for example, 4.43MHz.
color signal components are separated. Of course, such separation of the luminance signal component and color signal component can also be performed using a comb filter or the like.

The color signal components are inverted by an inverting circuit 7.

The switch 1 selects a signal inverted by the inverting circuit 7 or a signal not inverted from its contacts B and A, and outputs the selected signal.

The output of switch 1 is input to phase shift circuit 8, and its phase is delayed by 90 degrees. The switch 2 selects and outputs the signal phase-shifted by the phase shift circuit 8 or the signal not phase-shifted from its contact point C.

The switches 1 and 2 are switched as shown in FIG. 5 by a logic circuit 16 having a configuration as shown in FIG. 4, for example.

A logic 1 control signal is input to the terminal 24 when the jump direction is the reverse direction. In addition, a jump trigger pulse is input to the terminal 23, and the T-type flip-flop 3
1 is triggered by its negative edge. The T-type flip-flop 31 inverts the output supplied to the exclusive OR circuit 33 to logic 1 or logic 0 every time it is triggered.

Since the exclusive OR circuit 33 has a logic 1 input to one of its terminals, it outputs a logic opposite to the output of the flip-flop 31. T-type flip-flop 32 is triggered by the negative edge of the output - of exclusive OR circuit 33, and inverts its output to logic 1 or logic 0 each time it is triggered. After all, the flip-flop 32 inverts its output every time the jump trigger pulse is input twice (every two frames).

Switch switch 1. On the other hand, the flip-flop 31 inverts its output every time the jump trigger pulse is input (every frame), and switches the switch 2. Therefore, when a jump trigger pulse is input as shown in Figure 5(a), the contacts of switches 1 and 2 are switched as shown in Figure 5(b), so the phase of the signal output from switch 2 changes with each jump. It will be delayed by 90 degrees (for each frame). During jumps in the reverse direction, a color burst whose phase is advanced by 90 degrees for each jump is inputted from the bandpass filter 6, so that the phases of the color bursts outputted from the switch 2 are continuous after all.

On the other hand, when jumping in the forward direction, a logic O control signal is input to the terminal 24. Therefore, the output of the exclusive OR circuit 33 has the same logic as the output of the flip-flop 31, and as shown in FIG. 5(c), the phase of the signal output from the switch 2 changes every time the jump trigger pulse is input. 9
It will advance 0 degrees. During jumps in the forward direction, the phase of the color burst output from the bandpass filter 6 is delayed by 90 degrees for each jump.
Therefore, the phase of the color burst output is continuous.

The color burst signal whose phase has been made continuous in this way is input to a PLL circuit 10 having a 4.43 MHz reference signal oscillation circuit 9, and a color subcarrier signal is reproduced. Generally, the output of a PLL circuit has a phase shift of 90 degrees with respect to the input. As shown in FIG. 6, the color burst is switched to a phase of +135 degrees or -135 degrees every 1H, so the average phase is 1180 degrees. Therefore, the (RY) n-axis signal from the PLL circuit 10, that is, c.

It is assumed that Sωt is output.

The multiplier circuit 12 multiplies the output signal of the PLL circuit 10 by a signal whose phase has been inverted by the inverter circuit 11 to generate the next signal.

cosωtX(-cosωt) =-(cos2ωt+cosO)/2...(
1) The multiplier circuit 12 extracts only the 2ωt component from this signal and amplifies it twice to produce a signal e1 (3,: -cos2 ωt'
” Outputs @(2).

Since the PAL color signal e2 is quadrature two-phase modulated as shown in Fig. 6, e, = (B-Y) sin ωt + (R-Y) cos ωt (
In the case of nH)...(3) Or.

e, = (B-Y) sin ωt-(RY) cos ωt (
In the case of (n+1)H)...(4). Assuming that the color signal e2 is represented by equation (3), the multiplication circuit 13 multiplies the output of the switch 2 and the output of the multiplication circuit 12 to obtain a primary signal e1e2.

1 e2 =: ((B-Y) sin ωt + (RY) cos ωt)
(-cos2ωt) = -((B-Y) sinωtcos2ωt+(R-Y
)cosωtcos2ωt)==-((B-Y)si
n3ωt−(B−Y)sinωt+(R−Y)cos
ωt+ (RY) cos3 ωt)/2...(5) Only the ωt component is extracted from this signal and amplified twice, resulting in a signal e3 6, = (13Y) sin ωt- (R-Y) cosωt
・ ・ ・ (6) is output from the multiplication circuit 13.

As is clear from comparing equations (3) and (6), the signal e
, the (RY) axis is inverted with respect to the signal e.

Therefore, the switch 3 is switched every jump trigger pulse by the output of the flip-flop 31, and the signal e2 or e3 is
By alternately selecting , the (RY) axis of the color signal immediately after the jump is inverted with respect to that immediately before the jump (continuity of inversion is ensured).

The output of switch 3 (color signal) has a center frequency of 4,
It is input to the adder circuit 15 via the 43 MHz band pass filter 14, and the output of the low pass filter 5 (lI
i11 degree signal) and is output from the contact H of the switch 4 to the terminal 22.

[Problem that the invention seeks to solve]

In this manner, the conventional device switches three switches 1, 2, and 3 at the time of a frame jump. If the color signal levels between contacts A, B, and C of the three switches and between contacts E and F do not correspond correctly, color flicker will occur, so level adjustment is required at three locations.

Further, when the phase of the color subcarrier generated by the PLL circuit 1o shifts by α degrees, the phase of the corrected color (it) shifts by 2α degrees, and color flicker also occurs.

Therefore, it is also necessary to adjust the PLL circuit 10, and there are a total of four adjustment points.

In conventional devices, there are many places where adjustments need to be made, or even without adjustment, variations need to be strictly suppressed during design, so it is actually difficult to reduce color flicker. Furthermore, the number of parts is large and the configuration is complicated, resulting in high costs.

Furthermore, since the video signal is separated into a luminance signal and a color signal, and the color signal is processed and then added to the luminance signal, the band of the luminance signal is limited and the signal deteriorates.

Therefore, the present invention reduces the number of adjustment parts and parts, reduces color flicker with a simple configuration and low cost, and does not separate the video signal into a luminance signal and a color signal.
By processing the signal as is, signal deterioration is prevented.

[Means for solving problems]

The present invention provides a PAL video signal processing device including a first circuit to which a video signal is input, a second circuit to which the output of the first circuit is input, and a connection between the output of the first circuit and the second circuit. and a logic circuit that generates a signal to select the output.
One of the first circuit and the second circuit includes a first delay circuit that delays the input video signal by a time corresponding to a 180 degree phase difference of the color subcarrier signal; a first switch that selects a delayed video signal or an undelayed video signal; the other has a second delay circuit that delays an input video signal by 1H;
and a second switch for selecting a video signal delayed by the delay circuit or a video signal not delayed.

[Effect]

The video signal is not separated into a color signal component and a luminance signal component, and is output as is through the first circuit and the second circuit. The first circuit or the second circuit selects and outputs a signal delayed from the input video signal by a time corresponding to the 180 degree phase difference of the color subcarriers or a signal that is not delayed. The circuit selectively outputs a signal delayed by 1H or a signal not delayed from the input video signal. This selection is made in response to a signal generated by the logic circuit.

〔Example〕

FIG. 1 is a block diagram of a PAL video signal processing apparatus according to the present invention, and parts corresponding to those in FIGS. 3 and 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The operation during normal playback is similar to that described above.

In the jump mode, the video signal input from the terminal 21 is not separated into a luminance signal and a color signal, but is input to the delay circuit 41 as it is. The delay time of the delay circuit 41 is PAL
It is set to a value corresponding to a 180 degree phase difference of the color subcarriers of the system. In other words, since the frequency fc of the color subcarrier is 4.43MHz, it is 113ns (=
1/(4,43X10'X2)).

The switch 1 selectively outputs a signal delayed by the delay circuit 41 or a signal not delayed. Therefore, the output of the color subcarrier of contact B of switch 1 (output of delay circuit 41) is delayed by 180 degrees from the output of contact A (non-delayed output). In other words, the delay circuit 41 functions as a phase delay circuit of substantially 180 degrees with respect to the color subcarrier of the PAL signal.

The output of the switch 1 is set to LH (64μS) by the delay circuit 42.
) will be delayed. The switch 2 selectively outputs a signal delayed by the delay circuit 42 or a signal not delayed.

The frequency fc of the PAL color subcarrier signal is relative to the frequency f of the horizontal synchronization signal.

It is set so that fc=(2841/4+1/625)fw (7), and as described above, the phase of the color subcarrier at nH is 90 degrees ahead of the phase at (n+1)H. Therefore, the output of the contact of switch 2 (output of the delay circuit 42) is the output of contact C (non-delayed output).
This means that it is 90 degrees ahead. In other words, the delay circuit 42 substantially functions as a 90 degree phase advancing circuit for the color subcarrier of the PAL signal.

In this way, the delay circuits 41 and 42 function as phase shift circuits for the color subcarriers, but since the video signal containing not only the color signal but also the luminance signal is directly input to these circuits, the delay circuits 41 and 42 function as a simple phase shift circuit 1 inverting circuit, etc. cannot be substituted by

Switches 1 and 2 are switched by an output signal from logic circuit 16. This logic circuit 16 has basically the same configuration as that shown in FIG. However, terminal 24
Contrary to the above-described case, the control signal input to the control signal is logic 1 when the jump direction is the forward direction, and logic 0 when the jump direction is the reverse direction. As a result, the second
When a jump trigger pulse as shown in Figures (a,
The control signals shown in FIG. Therefore, the phase of the color subcarrier signal output from switch 2 is delayed by 90 degrees for each jump.

Furthermore, when the jump direction is the forward direction, the control signal shown in FIG. 2(d) is applied to switch 1.

Further, control signals shown in (8) in the figure are supplied to the switches 2, respectively. Therefore, the phase of the color subcarrier signal output from switch 2 advances by 90 degrees for each jump.

The phase of the color subcarrier in the video signal input from the terminal 21 advances by 90 degrees in the reverse direction and lags by 90 degrees in the forward direction for each jump, so the phase of the color subcarrier output from the switch 2 is continuous after all. .

On the other hand, as described above, the RY axis of the PAL system is reversed every 1 sec, so the first and last RY axes of one frame (625H) are in the same direction.

Therefore, when switch 2 is switched every frame jump, the RY axis after switching is reversed with respect to the RY axis before switching.

When playing still images, a video signal with a color signal shifted by 1H is output every other frame, but this poses almost no problem in practice.

Level adjustment can be done in two places, switches 1 and 2.

Further, delay circuits 41 and 42 do not require adjustment because delay time delay circuits with little variation can be easily obtained.

Note that the circuit consisting of the delay circuit 41 and switch 1 and the circuit consisting of the delay circuit 42 and switch 2 may be arranged in opposite positions.

Furthermore, the present invention can be applied not only to analog video signals but also to digital video signals.

〔effect〕

As described above, the present invention provides a first circuit to which a video signal is input in a PAL video signal processing device.

a second circuit into which the output of the first circuit is input; and a logic circuit that generates a signal for selecting the output of the first circuit and the output of the second circuit; One of the circuits includes a first delay circuit that delays an input video signal by a time corresponding to a 180 degree phase difference of the color subcarrier signal, and a video signal that is delayed by the first delay circuit or a video that is not delayed. a first switch for selecting a signal, and a second delay circuit for delaying an input video signal by 1H; and a second switch for selecting a video signal delayed by the second delay circuit or a video signal not delayed. Since the second switch is included, the number of adjustment points and parts can be reduced, and color flicker can be reduced with a simple configuration and low cost. Furthermore, since the color signal is processed as is without separating it from the luminance signal, the band of the luminance signal is limited and signal deterioration is prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a PAL video signal processing device of the present invention, FIG. 2 is a timing chart thereof, FIG. 3 is a block diagram of a conventional PAL video signal processing device, and FIG. 4 is a block diagram of its logic circuit. FIG. 5 is a timing chart thereof, and FIG. 6 is a vector diagram of a PAL video signal. 1 to 4...Switch 5...Low pass filter 6...Band pass filter 7...Inverting circuit 8...Phase shift circuit 9...Reference signal oscillation circuit 10...PLL circuit 11... - Inverting circuit 12.13...Multiplication circuit 14...Band pass filter 15...Addition circuit 16...Logic circuits 21 to 25...Terminals 31.32...T-type flip-flop 33... Exclusive OR circuit 41...delay circuit 42...delay circuit or higher

Claims (1)

[Claims] A first circuit to which a video signal is input, a second circuit to which the output of the first circuit is input, an output of the first circuit and an output of the second circuit. a logic circuit that generates a signal for selecting a color subcarrier signal, and one of the first circuit and the second circuit controls the input video signal for a time corresponding to a 180 degree phase difference of the color subcarrier signal. a first delay circuit that delays;
a first switch for selecting the video signal delayed by the delay circuit or the video signal not delayed;
The other one includes a second delay circuit that delays the input video signal by 1H, and a second switch that selects the video signal delayed by the second delay circuit or the video signal that is not delayed. Features of PAL video signal processing device.