JPH02270496A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve an S/N by providing a 1st noise elimination means eliminating noise through the addition of a delay signal and a non-delay signal of a color signal and a 2nd noise elimination means retarding a luminance signal by one horizontal scanning time, subtracting the delay signal and the non-delay signal, limiting the amplitude, extracting a noise component and adding or subtracting the noise component and the delay signal of the luminance signal. CONSTITUTION:A horizontal correlation noise canceller 15 consists of a 1H CCD delay line(1HDL) 16, a differential amplifier 17, a limiter(LIM) 18 and an adder 19. The main signal delay system horizontal correlation noise canceller 16 uses the strong horizontal correlation to improve the S/N of the luminance signal and the differential amplifier 17 subtracts the luminance signal passing through the 1H delay line 16 and the luminance signal not passing therethrough and the result is limited to a prescribed amplitude by the limiter 18 to obtain only a noise component without horizontal correlation. The noise component is mixed with the luminance signal (main line signal) passing through the 1H delay line 16 in the adder 19 and the noise component of the luminance signal of the main line outputted from the adder 19 is reduced to improve the S/N.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording/reproducing device, in particular, to eliminate the vertical deviation between a luminance signal and a chrominance signal during reproduction, and at the same time improve the image quality of the reproduced luminance signal. It is related to things that have been done in this way.

[Conventional technology]

Figure 2 shows an example of the playback section of a conventional magnetic recording/playback device, where ■ is a magnetic tape, 2 is a video head, 3 is a preamplifier, and 4 is a low-pass filter (L) that passes low-frequency color signals.
PF), 5 is ACC (Auto-matic C
6 is a frequency converter (CONV), 7 is a band pass filter (BPF) that passes color signals, 8 is a comb filter for color signals, 11 is a color killer circuit (KILL), 12 is F
Bypass filter (HPF) that passes the M luminance signal
, 13 is an FM demodulator (DEM), 14 is a low-pass filter (LPF) that passes the luminance signal, 26 is a horizontal correlation noise canceler circuit, and 25 is a mixer for the luminance signal and color signal. The comb filter 8 is composed of a 2H (H is one horizontal scanning time) glass delay line (2HDL) 9 and an adder 10, and the horizontal correlation noise canceler circuit 26 is an IH
It is composed of a COD (charge-coupled device) delay m27, a differential amplifier 28, a mink 29, and an adder 30.

Next, the operation will be explained. A video head 2 reads out a composite signal of an FM-modulated luminance signal and a low-frequency converted color signal from a magnetic head l, and this composite signal is amplified by a preamplifier 3 and then filtered through a low-pass filter 4.
and a bypass filter 12, and are separated into a low-pass converted color signal and an FM luminance signal, respectively. The low-pass converted color signal that has passed through the low-pass filter 4 is controlled by the ACC circuit 5 to suppress the fluctuation component of the amplitude of the color burst signal and to maintain a constant value. 6, the signal is high-frequency converted to a color signal of the original color subcarrier frequency, and at the same time is controlled to suppress the frequency and phase fluctuation components of the signal, and then passed through a bandpass filter 7 and output as a color signal. Ru. This color signal contains crosstalk components and noise components from adjacent video trunks on the magnetic tape 1, and these components are removed by the comb filter 8, leaving only the color signal with an improved S/N ratio. is extracted. This signal is the color killer circuit 11
The signal is sent to a mixer 25 for luminance and chrominance signals.

On the other hand, the FM luminance signal that has passed through the bypass filter 12 is demodulated by the FM demodulator 13, and is then demodulated by the low-pass filter 14.
The M carrier component is removed and output.

Here, there is a noise canceler as a method to improve the S/N ratio of the luminance signal, and the principle of this is to extract only the high frequency components of the luminance signal, and mix the noise components sliced at a certain level with the original luminance signal. This method aims to improve the S/N ratio, but when the S/N ratio improvement effect is increased, the noise in the outline of the image is not removed, the edges look dirty, or the signal is high. The disadvantage was that the area was missing, resulting in a screen with no details.

Therefore, a horizontal correlation noise canceller 26 is used to eliminate this drawback, and this takes advantage of the strong horizontal correlation of the signals. By subtracting the current main signal from the current main line signal using the differential amplifier 28, and limiting the amplitude to a certain constant amplitude using the limiter 29, only noise components having no horizontal correlation can be obtained. This noise component is mixed with the output of the low-pass filter 14 in the adder 30, the noise component of the original luminance signal is reduced, and the S/N ratio is improved. Normally, this horizontal correlation noise canceler 26 and a noise canceler are used together. be done. The luminance signal obtained by the adder 30 is mixed with the color signal in the mixer 25.

[Problem to be solved by the invention]

In the conventional device described above, the comb filter 8 is essential as a means for improving the S/N ratio of the reproduced color signal, and in the case of a PAL magnetic recording and reproducing device, as shown in FIG.
(Specifically, a value close to 2H that is an integer multiple of the period τ of the color subcarrier, usually 567τ - 127,886 μs) delay line 9
By adding the delayed signal and the non-delayed signal at the same level using the adder IO, it is set so that color signals are added in-phase, and noise components are canceled out by anti-phase addition. There is.

However, in the part where the color signal has no horizontal correlation, that is, in the boundary part between the colorless part and the certain part within one vertical scanning period (-1v), the output of the comb filter 8 continues over the 2H period as shown in FIG. An intermediate value appears between the input of the comb filter 8 shown in FIG. 4 ta+ and the output of the 2H delay line 9 shown in FIG. 4 Cb). On the other hand, since the main line signal of the luminance signal shown in Fig. 4 (di) is not delayed, the fourth
As shown in Figure In, only the color signal appears to be shifted downward.

In the PAL television system, since the screen uses an interlaced scanning system, 2H corresponds to four scanning lines, resulting in an extremely unsightly playback screen.

This invention was made to solve the above-mentioned problems, and it improves the S/N ratio and also improves the downward direction of the color signal in the composite video signal of the luminance signal and color signal on the playback screen. An object of the present invention is to obtain a magnetic recording/reproducing device that can eliminate misalignment.

[Means to solve the problem]

The magnetic recording/reproducing device according to the present invention includes a first noise removing means for removing noise by adding a delayed signal and a non-delayed signal of a color signal, and a first noise removing means for removing noise by adding a delayed signal and a non-delayed signal of a color signal; A second noise removing means is provided which extracts a noise component by subtracting the delayed signal and limiting the amplitude, and adds or subtracts this noise component and the delayed signal of the luminance signal.

[For production]

The first noise removal means in this invention adds the delayed signal and the non-delayed signal of the color signal, thereby canceling out the noise component in the color signal. Further, the second noise removing means according to the present invention delays the luminance signal by one horizontal scanning time, extracts a noise component from the delayed signal and the non-delayed signal, and removes this noise component from the luminance signal. Noise components are removed from the luminance signal and the color signal, and the luminance signal is delayed by one horizontal scanning time and mixed with the color signal.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
The figure shows the configuration of the reproducing portion of the magnetic recording and reproducing apparatus according to this embodiment, and 15 is a main signal delay type horizontal correlated noise canceller, which is provided in place of the conventional horizontal correlated noise canceller 26.

Other configurations are the same as before. The horizontal correlation noise canceller 15 includes an LH CCD delay line (IHDL) 16, a differential amplifier 17, a limiter (LIM) 18, and an adder 19.

In the above configuration, the horizontal correlation noise canceller 15 using the main signal delay method improves the S/N ratio of the luminance signal by utilizing the strong horizontal correlation of the signals. By subtracting the signal and the luminance signal that does not pass by the differential amplifier 17 and limiting the amplitude to a constant amplitude by the chisel 18, only noise components without horizontal correlation are obtained. This noise component is added to I in the adder 19.
The noise component of the main line luminance signal that is mixed with the luminance signal (main line signal) that has passed through the H delay 116 and output from the adder 19 is reduced, and the S/N ratio is improved. Further, the luminance signal output from the adder 19 is delayed by IH as shown in FIG. Figure ff
), other effects that do not cause vertical displacement as shown in
The operation is the same as before.

FIG. 5 shows a second embodiment of the present invention, in which 20 is a horizontal correlated noise canceler circuit corresponding to the horizontal correlated noise canceler circuit 26, which is composed of an IHCCD delay line 21, a differential amplifier 22, a limiter 23, and an adder 24. configured,
Its operation is similar to that of the horizontal correlation noise canceller circuit 26. Therefore, the noise component of the luminance signal is removed in two stages by the noise canceller 15.20, making it possible to further improve the S/N ratio. Moreover, since the luminance signal output from the noise canceller 20 is delayed by IH, it matches the chrominance signal and no positional deviation occurs.

FIG. 6 shows the configuration of a vertical contour emphasizing circuit used in the third embodiment of the present invention, and the circuit is shown in FIGS.
It is used in place of the horizontal correlation noise canceller 15 shown in the figure. The vertical contour emphasizing circuit is for emphasizing horizontal lines in uncorrelated parts in the vertical (longitudinal) direction of the screen. In Fig. 6, 31.33 is an IH CCD delay line, 32.34 is a differential amplifier, 35.37 is an adder, and 36.
is the vertical contour control circuit.

In the above configuration, the input signal A shown in FIG. 7(a) is l
IH is delayed by the HCCD delay line 31, and the
1, and the signals B and A are subtracted by the differential amplifier 32. Also, the signal B is delayed by IH by the IHCCD delay line 33 and is delayed by 2H from the signal A as shown in FIG. 7(C).
The signal B and C are subtracted by the differential amplifier 34, and the output of each differential amplifier 32 and 34 is sent to the adder 3.
After mixing in step 5, the vertical contour control circuit 36 adjusts the level to double the amplification degree that sets the degree of vertical contour emphasis (0<k<1, the larger the k value, the higher the degree of contour emphasis), as shown in FIG. The signal becomes as shown in FIG. 7(d), and this signal is further added to the signal B in an adder 37, resulting in the output shown in FIG. 7(e).

Since this output also has noise components removed from the original luminance signal and becomes a signal delayed by IH, it has the same effect as the above embodiment. Note that the vertical direction of each signal in FIG. 7 represents the black and white level.

FIG. 8 shows the configuration of a vertical contour enhancement circuit used in a fourth embodiment of the present invention, and this circuit is used in place of the horizontal correlation noise canceler 15 shown in FIGS. 1 and 5. 38 is an adder, and 39 is a differential amplifier.

In the above configuration, the input signal A in FIG. 9(a) and the output of the vertical contour control circuit 36 in tc+ in FIG. 9 are added by the adder 38, and then IH delay 1i131'? ! The signal is delayed by 1H and becomes signal B in Fig. 9). Signals A and B are differential amplifiers 32
is subtracted by , and multiplied by k (
A-B), and the signal B,k (A-B) is subtracted by the differential amplifier 39, resulting in the output shown in FIG. 9 Tdl. This output is also IH delayed and has the same effect as the above embodiment.

Note that the horizontal correlation noise canceller 15 can also have a feedback type (cyclic type) configuration in the same manner as shown in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the noise components of the chrominance signal and the luminance signal are canceled out and removed by their delayed signals, thereby improving the S/N ratio and improving the image quality. Further, since the luminance signal is delayed by one horizontal scanning time and mixed with the color signal, and the color signal is also substantially delayed by one horizontal scanning time, it is possible to eliminate the vertical deviation between the two.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the reproduction section of a magnetic recording and reproduction apparatus according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of the reproduction section of a conventional apparatus, and FIG. 3 is a configuration diagram of a color signal comb filter. Fourth
5 is a diagram showing the operation waveforms of various parts of the present invention and the conventional device. FIG. 5 is a configuration diagram of the reproducing portion of the magnetic recording and reproducing device according to the second embodiment of the present invention. FIGS. FIGS. 8 and 9 are block diagrams and operational waveform diagrams of a vertical contour emphasizing circuit according to a fourth embodiment of the present invention. FIGS. 1... Magnetic tape, 2... Video head, 4...
Low-pass filter, 8...Comb filter, 9...2
H delay line, 10, 19, 24, 35, 37, 38...
Adder, 12... Bypass filter, 15.20...
・Horizontal correlation noise canceller, 16, 21, 31.33
...IH delay line, 17.22.32.34.39...
・Differential amplifier, 18.23...Limiter, 25...
Mixer, 36...vertical contour control circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A means for reading a color signal and a luminance signal recorded on a magnetic medium, a means for separating the read color signal and a luminance signal, and noise removal by adding a delayed signal and a non-delayed signal of the separated color signal. A first noise removing means for performing the noise removal, delays the separated luminance signal by one horizontal scanning time, subtracts the delayed signal and the non-delayed signal of the luminance signal, limits the amplitude, extracts the noise component, and extracts the noise component. A magnetic recording/reproducing apparatus comprising: second noise removing means for adding or subtracting a luminance signal from a delayed signal; and means for mixing outputs of the first and second noise removing means.