JPH0224308Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a carrier color signal reproducing device, and more particularly, to a carrier color signal reproducing device that de-emphasizes and reproduces the vertical spatial frequency of the carrier color signal. Regarding.

BACKGROUND TECHNOLOGY In a recording and reproducing apparatus such as a VTR, a luminance signal and a carrier color signal are separated from a color video signal to be recorded and reproduced, each is subjected to predetermined signal processing, and then both signals are multiplexed and recorded. In the case of reproduction, noise has conventionally been reduced using line correlation for the carrier color signal as well as for the luminance signal. In other words, while the reproduced carrier color signal usually has line correlation, most of the noise mixed in the reproduced carrier color signal has no line correlation. By mixing the carrier color signals to extract noise that has no line correlation, and mixing this noise with the reproduced carrier color signal through a limiter, it is possible to extract a reduced reproduced carrier color signal in which the noise is canceled out.

However, in the conventional recording/reproducing apparatus having the above-mentioned noise reduction circuit, for a reproduced carrier color signal having no line correlation, signal components having no line correlation are also subtracted from the input reproduced carrier color signal along with the noise. Therefore, there was a problem that the spatial frequency characteristics in the vertical direction (vertical resolution) deteriorated.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 138872/1983 that pre-emphasis was applied to the air conditioning frequency characteristics in the vertical direction for the carrier color signal to be recorded.
Furthermore, we have proposed a recording and reproducing apparatus for a carrier color signal that provides a de-emphasis characteristic complementary to the above-mentioned pre-emphasis characteristic to the reproduced carrier color signal. According to this proposed recording/reproducing device, the vertical spatial frequency characteristics (vertical resolution) due to de-emphasis will not deteriorate as in conventional noise reduction circuits that utilize line correlation, and the carrier color signal with large amplitude will not deteriorate. Since non-linear pre-emphasis is performed in which pre-emphasis is not applied too much, the amount of overshoot due to pre-emphasis can be reduced, and the S/ N
Almost no deterioration of ratio or moiré, etc.
In a recording/reproduction device that can improve the S/N ratio of the carrier color signal and is equipped with only either a nonlinear pre-emphasis circuit or a non-linear de-emphasis circuit, the amplitude of the carrier color signal is not so emphasized during recording and reproduction. Therefore, it is possible to reproduce the carrier color signal reproduced from the magnetic tape recorded by the current VTR into the original signal waveform with almost no practical problems even if it is passed through a non-linear de-emphasis circuit. It also has the advantage of being able to be reproduced into the original carrier color signal waveform with virtually no practical problems using current VTRs, and thus compatible with current VTRs.

Problems to be Solved by the Invention However, whereas the de-emphasis circuit in the recording and reproducing device proposed above had a delay circuit whose delay time was fixed to one horizontal scanning period (1H), variable speed reproduction Sometimes, because the relative linear velocity between the tape and the head is different from that during recording or normal playback, the playback horizontal synchronizing signal frequency becomes a value that is slightly different from the normal horizontal scanning frequency, so the delay circuit described above cannot accurately calculate the 1H delay. I couldn't get it. For this reason, the de-emphasis characteristics of the de-emphasis circuit are no longer complementary to the pre-emphasis characteristics of the pre-emphasis circuit of the recording system, resulting in the problem that color bleeding occurs diagonally downward on the screen from the image change area where there is no line correlation on the screen. It was hot.

Therefore, the present invention solves the above problem by substantially stopping the operation of the de-emphasis circuit that de-emphasizes the spatial frequency in the vertical direction with respect to the carrier color signal during variable speed reproduction. The purpose is to provide a playback device.

Means for Solving the Problems The carrier color signal reproducing device according to the present invention comprises a de-emphasis circuit and a switch circuit means. The de-emphasis circuit has a vertical de-emphasis characteristic that relatively attenuates the level of the high-frequency component of the vertical spatial frequency of the carrier color signal reproduced from the recording medium compared to the low-frequency component. Further, the switch circuit means passes through and outputs the input reproduced carrier color signal as it is during variable speed reproduction, and selectively outputs the reproduced carrier color signal to which the vertical de-emphasis characteristic has been imparted during reproduction other than variable speed reproduction.

Operation During variable speed reproduction, the reproduced carrier color signal input to the de-emphasis circuit is passed through and output as it is by the switch circuit means without being de-emphasized by the de-emphasis circuit. That is, during variable-speed reproduction, the de-emphasis circuit is substantially stopped from operating, and therefore, a reproduced conveyance color signal free of color blur, which is produced as a result of applying vertical de-emphasis characteristics, is taken out at the output terminal.
Hereinafter, each embodiment of the present invention will be described with reference to the drawings.

Embodiment FIG. 1 shows a block diagram of a first embodiment of the device of the present invention. For example, a reproduced carrier color signal reproduced from a magnetic tape by a rotating head of a VTR and extracted through a known signal processing system is supplied via a terminal 1 to a subtraction circuit 2, an addition circuit 3, and a coefficient circuit 4, which will be described later. be done. Note that this input reproduced carrier color signal is given in advance a pre-emphasis characteristic complementary to the characteristic of this de-emphasis circuit at the time of recording, and the high-frequency component of the spatial frequency in the vertical direction is emphasized.

The output carrier color signal of the subtraction circuit 2 is sent to the 1H delay circuit 5.
After being delayed by 1H, it is supplied to the coefficient circuit 6,
Here, the signal is multiplied by a coefficient L ₁ (for example, 0.87) and then supplied to the phase adjuster 7 . It is supplied to the phase adjuster 7. The phase adjuster 7 is accurately controlled by the 1H delay circuit 5.
If a delay time of 1H can be obtained, this circuit is unnecessary.
However, the delay time actually obtained by the 1H delay circuit 5 is not exactly 1H, and in this case, the output signal of the coefficient circuit 6 is supplied to the subtraction circuit 2 without phase adjustment, and the input carrier color signal and the subtraction operation are performed. If this is done, the coefficient L ₁ will equivalently decrease, and the desired de-emphasis characteristic will not be obtained.

Therefore, by adjusting the phase of the output signal of the coefficient circuit 6 using the phase adjuster 7 so that it becomes the same as the phase of the carrier color signal delayed by 1H,
The required de-emphasis characteristics can be obtained. However, this phase adjuster 7 is a circuit for performing optimal phase adjustment during normal playback, and as mentioned above, during variable speed playback, the frequency of the playback horizontal synchronization signal is different from the normal value, so the 1H delay circuit 5 cannot accurately adjust the phase. A suitable 1H delay amount cannot be obtained, and even if the phase adjuster 7 is used, a phase error will occur.

The subtraction circuit 2 performs a subtraction operation of subtracting the output signal of the phase adjuster 7 from the reproduced carrier color signal from the input terminal 1. Here, as is well known, the color subcarrier frequency of the carrier color signal in the NTSC system is equal to the horizontal scanning frequency.
227.5 times, and for fractions of 0.5 the color subcarrier is
At the beginning and end of 1H, the phase is 0.5 period, i.e.
The difference is 180℃. Therefore, the carrier color signal extracted after being accurately delayed by 1H from the phase adjuster 7 is
If there is a line correlation with the reproduced carrier color signal input from input terminal 1, the relationship is in reverse phase, and the subtractor circuit 2 takes out a carrier color signal that is substantially added to the carrier color signal 1H before. It will be. The output carrier color signal of this subtraction circuit 2 is supplied to a 1H delay circuit 5, and is also supplied to a coefficient circuit 8, where it is multiplied by a coefficient L ₂ (for example, 0.18) and then passed through a phase adjuster 9 to an addition circuit 3. is supplied to

The adder circuit 3 performs an operation of adding the input reproduced carrier color signal and the output carrier color signal of the phase adjuster 9, and outputs the obtained signal to the terminal 10a of the switch circuit 10 as a de-emphasized carrier color signal. Here, the phase adjuster 9 is provided to accurately adjust the phase of the two-input reproduced carrier color signal in the adder circuit 3. Furthermore, in the output signal of the adder circuit 3, the level of the high-frequency component of the input reproduced carrier color signal in the vertical direction of the screen is relatively attenuated compared to the low-frequency component, regardless of the amplitude of the input reproduced carrier color signal. The reproduced carrier color signal is given a vertical de-emphasis characteristic.

On the other hand, the input reproduced carrier color signal multiplied by the coefficient _L3 by the coefficient circuit 4 and extracted is applied to the terminal 10b of the switch circuit 10. Here, the above coefficient _L3 is such that when the reproduced carrier color signal with line correlation is input, the output reproduced carrier color signal level of the coefficient circuit 4 is
This is provided in order to make the level equal to the output reproduced carrier color signal level of the adder circuit 3.

The switch circuit 10 is configured to be switched controlled by a switching signal inputted to a terminal 11. This switching signal is a binary signal that has different logical values during variable speed playback and playback other than variable speed playback (normal playback), and during variable speed playback, the switch circuit 10 selects and outputs the input signal of terminal 10b. On the other hand, during normal playback, the switch circuit 10 is controlled to selectively output the input signal of the terminal 10a.

Therefore, during normal playback, the switch circuit 10
The output de-emphasized reproduced carrier color signal of the adder circuit 3 is taken out to the output terminal 12, and during variable speed reproduction, the input reproduced carrier color signal that has passed through the coefficient circuit 4 is sent directly to the switch circuit 10 without being given the de-emphasis characteristics described above. The signal is output to the output terminal 12 through.

Next, a second embodiment of the apparatus of the present invention will be described. FIG. 2 shows a block system diagram of the second embodiment of the apparatus of the present invention. In the figure, the same components as in FIG. 1 are denoted by the same reference numerals, and their explanations will be omitted. While the first embodiment provides a preset fixed de-emphasis characteristic regardless of the amplitude of the input reproduced carrier color signal, the present example provides a variable de-emphasis characteristic depending on the amplitude of the input reproduced carrier color signal. It is characterized by the fact that it is given. The output signal of the subtraction circuit 2 is multiplied by a predetermined coefficient (for example, 0.13) in a coefficient circuit 15 and then supplied to the subtraction circuit 14 via a phase adjuster 9.

Here, it goes without saying that, like the terminal 1, the input terminal 13 is supplied with a signal obtained by reproducing a carrier color signal to which a pre-emphasis characteristic has been given in advance with respect to the spatial frequency in the vertical direction at the time of recording. However, a reproduced signal of a carrier color signal recorded by a current VTR and not provided with the above-mentioned pre-emphasis characteristics may also be supplied. This input reproduced carrier color signal is subtracted from the output signal of the phase adjuster 9 in the subtraction circuit 14 and then supplied to the non-linear circuit 17.

The non-linear circuit 17 is, for example, an amplitude limiter that limits the amplitude of an input signal to a constant value, and is configured to pass through and output an input signal with an amplitude smaller than this constant value as it is without amplitude limiting. ing. The carrier color signal taken out from the non-linear circuit 17 is converted into a coefficient (for example, approximately
0.57) and then supplied to the switch circuit 19.

The switch circuit 19 is controlled by the switching signal from the terminal 11 so that it is turned off during variable speed playback and turned on during normal playback. As a result, the signal taken out from the coefficient circuit 18 is sent to the switch circuit 1 only during normal playback.
9 and is supplied to a subtraction circuit 20, where:
By being subtracted from the input reproduced carrier color signal from the input terminal 13, a reproduced carrier color signal to which a non-linear de-emphasis characteristic is imparted at vertical spatial frequencies is extracted and outputted to the output terminal 21.

This non-linear de-emphasis characteristic is like a comb filter, where fH is the horizontal scanning frequency, frequencies that are odd multiples of fH/2 are attenuation poles, and frequencies that are even multiples of fH/2 are passbands. This shows a variable frequency characteristic in which the amount of de-emphasis gradually decreases as the amplitude of the input reproduced carrier color signal increases.

On the other hand, since the switch circuit 19 is turned off during variable speed reproduction, the transmission of the output signal of the coefficient circuit 18 is blocked by the switch circuit 19, and as a result, the input reproduced carrier color signal from the input terminal 13 is transmitted from the subtraction circuit 20. It is taken out as is and output to the output terminal 21. Therefore, during variable speed reproduction, the input reproduced carrier color signal is output to the output terminal 21 as it is without being given de-emphasis characteristics.

Note that the present invention is not limited to the above-described embodiment; for example, the switch circuit 19 may be replaced by the subtraction circuit 1.
4. The de-emphasis circuit in the recording and reproducing apparatus proposed by the present applicant, which may be provided on the output side of either one of the non-linear circuits 17 and which imparts de-emphasis characteristics for spatial frequencies in the vertical direction, is applied. Furthermore, it can also be applied to carrier color signals such as the PAL system.

Effects of the Invention As described above, according to the present invention, the de-emphasis circuit is substantially inactive during variable-speed reproduction, so a reproduced carrier color signal that is not de-emphasized with respect to vertical spatial frequencies can be obtained, so that image (color) It is possible to prevent the occurrence of color bleeding that occurs diagonally downwards on the screen from sharply changing parts, and since the above-mentioned de-emphasis characteristic is not applied during this variable speed playback, the noise reduction effect is lost, but the image quality deterioration due to it is diagonal. Since it is comparatively smaller than the above-mentioned color fringing that occurs in the lower part, it has the advantage of being able to obtain variable speed reproduction images of practically sufficient image quality.

[Brief explanation of the drawing]

FIGS. 1 and 2 are block diagrams showing respective embodiments of the device of the present invention. 1, 13...Reproduction carrier color signal input terminal, 2, 1
4,20...Subtraction circuit, 3...Addition circuit, 4,
6, 8, 15, 18... Coefficient circuit, 5... 1H delay circuit, 7, 9... Phase adjuster, 10, 19...
Switch circuit, 11... Switching signal input terminal, 12, 21... Conversion de-emphasis carrier color signal output terminal, 17... Non-linear circuit.

Claims (1)

[Claims for Utility Model Registration] 1. A carrier color signal reproduced from a recording medium is supplied, and the level of the high frequency component of the vertical spatial frequency of the reproduced carrier color signal is attenuated relative to the low frequency component. A de-emphasis circuit having a de-emphasis characteristic in the vertical direction; and a de-emphasis circuit that allows the reproduced carrier color signal inputted to the de-emphasis circuit to pass through as it is without imparting the de-emphasis characteristic in the vertical direction only during variable-speed reproduction, and during reproduction other than the variable-speed reproduction. A carrier color signal reproducing device comprising switch circuit means for selectively outputting a reproduced carrier color signal to which a directional de-emphasis characteristic is imparted. 2. The de-emphasis circuit imparts a preset de-emphasis characteristic in the vertical direction to the input reproduced carrier color signal regardless of the amplitude of the input reproduced carrier color signal.
A reproducing device for a carrier color signal as described in 2. 3. The de-emphasis circuit imparts to the input reproduced carrier color signal a non-linear de-emphasis characteristic that allows the vertical de-emphasis characteristic to be variably controlled in accordance with the amplitude of the input reproduced carrier color signal. A reproducing device for a carrier color signal as described in 2.