JPH0365894A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device, and particularly to chroma signal processing in a household magnetic recording/reproducing device.

[Conventional technology]

FIG. 3 is a diagram showing a magnetic recording and reproducing device having a conventional chroma signal processing circuit. In the figure, 1 indicates a chroma signal;
2 is a comb filter circuit, 3 is a changeover switch, 4 is a band pass filter, 5 is a converter circuit, 6 is a low pass filter, 7 is a ξx circuit, 8 is a recording amplifier, 9 is a head, 10 is a tape, 11 is an FM A modulator, 12 is a non-correlation detection circuit, 20 is an input terminal, 21 is an IH (-horizontal period) delay circuit, 22 is a cyclic addition circuit, 23 is a subtraction circuit, and the non-correlation detection circuit 12 is composed of 20 to 23. has been done. 100 is a magnetic recording/reproducing circuit.

Next, the operation will be explained.

When recording a chroma signal, the phase of the chroma signal is shifted by 180° for each IH in the NTSC signal, so by passing it through the comb-shaped filter circuit 2, unnecessary luminance signal components around 3.58 MHz are removed. This is to reduce interference such as cross color by subjecting the 3.58 MHz luminance signal to chroma signal processing. Therefore, the chroma signal that has passed through the comb-shaped filter circuit 2 passes through the bandpass filter 4, and only the 3.58MHz±500KHz component is converted into a low-frequency chroma signal of 629KHz by the converter circuit 5.
It is converted to ±500KHz, low pass filter 6, recording amplifier 8. The head 9 records the data onto the tape 10 . The luminance signal is ξ-axed by an FM modulator 11 ξ-xx circuit 7 .

Also, passing the comb-shaped filter circuit 2 during recording is 2H.
Since the average is taken, the IH portion will be discolored when the color changes. Therefore, as a countermeasure against color fading, the non-correlation detection circuit 12 outputs an error signal when there is a change in the vertical direction, that is, when there is a difference between the signal before IH and the current signal, and outputs the error signal. The switch 3 switches whether the chroma signal is passed through the comb filter circuit 2 or bypassed. This makes it possible to prevent discoloration in non-correlated areas, which are areas where discoloration is conspicuous in the vertical direction, but it cannot be expected to be very effective unless the sensitivity of the output of the non-correlation detection circuit is significantly increased. As a result, most of the comb filter circuit 2 is in a bypass state, and removal of the original luminance signal is incomplete, resulting in problems such as cross color.

In addition, in the non-correlation detection circuit 12, if there is a change in the vertical direction, when the horizontal signal is added twice to the variable that is less than 1 of the signal before IH and subtracted from the current signal, an error is detected. occurs. In other words, the same applies to video signals and chroma signals, but I Hde
The result of multiplying the IH-delayed signal by the lay circuit 21 and adding it cyclically to the current portion (Fig. 4 (a)
)) results in the error portion shown in FIG. 4(b).

[Problem to be solved by the invention]

Conventional magnetic recording and reproducing devices are at the bottom as described above, and in order to prevent discoloration based on the output of a non-correlation detection circuit, most of the time, a comb-shaped filter circuit is used to fully obtain the effect of the non-correlation detection circuit. There is a problem in that the filter enters a bypass state and cannot perform the original processing of the comb-shaped filter circuit.

This invention was made in order to solve the above-mentioned problems, and its purpose is to provide a magnetic recording and reproducing device that can improve color fading and can sufficiently perform the processing of the original comb-shaped filter circuit. shall be.

[Means to solve the problem]

The magnetic recording/reproducing device according to the present invention detects the saturation level of a chroma signal, fixes a switch on the comb-shaped filter circuit side so that all chroma signals with low saturation pass through the comb-shaped filter circuit, and detects the saturation level of the chroma signal. A switch is operated so that a high chroma signal passes through or bypasses the comb filter circuit depending on the output of the non-correlation detection circuit.

[Effect]

In this invention, since the chroma signal is passed through or bypassed to the comb-shaped filter circuit depending on the saturation level, color fading is improved for chroma signals with high saturation where color fading is particularly noticeable, and color fading is improved for other chroma signals. can be sufficiently processed by a comb filter circuit.

〔Example〕

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

FIG. 1 is a diagram showing the configuration of a magnetic recording/reproducing apparatus according to an embodiment of the present invention during recording. In the figure, the same symbols as in the conventional example indicate the same parts, 31 is a capacitor C, 32 is a coil Ll. , 33 is a transistor Q, , 34 is a capacitor C! , 35 is the voltage, 36 is the resistor R, 37 is the resistor R1, 3B is the comparator, 39 is the diode DI, 4
0 is a resistor R3, 41 is a resistor R4, and 200 is a saturation detection circuit.

FIG. 2 is a diagram showing the configuration of a magnetic recording and reproducing apparatus according to an embodiment of the present invention during reproduction. In the figure, the same reference numerals as in FIG. head, 53 is a head amplifier, 54 is a low-pass filter (
55 is a converter (CONV), 56 is a band pass filter (BPF), 57 is a comb filter,
58 is a changeover switch, 59 is an amplifier, 60 is a luminance signal, 61 is a ξTx circuit, and 62 is a video signal.

Next, the operation will be explained.

The circuit 100 that records the chroma signal on the tape by allowing the chroma signal to pass through or bypass the comb filter circuit by using a switch that is changed based on the output of the error signal of the non-correlation detection circuit is the same as the conventional one. Then, the saturation level of the chroma signal is determined by the saturation level detection circuit 200, and the switch 3 is fixed so that the chroma signal with a low level of saturation always passes through the comb-shaped filter circuit 2.
For highly saturated chroma signals, a non-correlation detection circuit 12
The switch 3 is operated based on the signal.

That is, during recording, chroma signal 1 is transmitted through transistor Q.
, 33, capacitor Cl31. Coil L.

32 to increase the gain in the 3.58MHz component, and it is integrated by capacitor C234 and resistor R441,
The saturation level of the chroma signal is converted to a DC level. And resistance R+ 36. A certain voltage V135 set by Rz37 and the DC level of the saturation of the converted chroma signal are compared in the comparator 38, and in the part where the saturation is low, the output of the comparator 3 is rL
ow" and the diode "D139 becomes conductive, so the output signal of the decorrelation circuit 12 is not input to the changeover switch 3 due to the impedance of the resistor R340.In other words, the switch 3 is turned off for a chroma signal with a low degree of saturation. It is always on the comb-shaped filter circuit side.On the other hand, for highly saturated chroma signals, the output of the comparator 38 is rHigh, but when the diodes D and 39 are OFF.
The switch 3 is switched depending on the presence or absence of the output error signal (FIG. 4(b)) of the non-correlation detection circuit 12. As a result, when the chroma signal is highly saturated and there is a non-correlated part, the comb-shaped filter circuit 12 enters a bypass state, so that color fading is improved.

In addition, the comb-shaped filter circuit 2, which should remove crosstalk from the chroma signal during playback, is bypassed only when the saturation level of the chroma signal is high based on the output signal of the non-correlation detection circuit, improving color fading of the chroma signal. do.

That is, the head 52 . head amp 5
The luminance signal of the reproduced signal is separated by the LPF 54 to become a 629 KHz low-frequency chroma signal, which is converted by the converter 55 to a 3.58 MHz chroma signal. Thereafter, unnecessary components are removed by the BPF 56 and the signal is input to the comb filter circuit 57. Here, the comb-shaped filter circuit 57 removes crosstalk caused by adjacent drag of the chroma signal. Here, as in the embodiment described above, focusing only on cases where the chroma signal has a high degree of saturation, the switch 58 switches whether to pass or bypass the comb-shaped filter circuit 57 based on the output of the non-correlation detection circuit 12. It is possible to prevent color fading of chroma signals. Thereafter, the chroma signal passes through the amplifier 59 to the ξx circuit 61.
The signal is mixed with a luminance signal at a video signal 62, and output as a video signal 62.

〔Effect of the invention〕

As described above, according to the present invention, the saturation level of the chroma signal is detected, the switch is fixed to the comb-shaped filter circuit side so that the chroma signal with low saturation passes through the comb-shaped filter circuit, and the chroma signal with high saturation is fixed to the comb-shaped filter circuit side. A switch is operated so that the chroma signal passes or bypasses the comb-shaped filter circuit depending on the output of the non-correlation detection circuit, which improves color fading especially for highly saturated chroma signals where fading is easily noticeable. This has the effect that other chroma signals can be sufficiently processed by the comb filter.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a magnetic recording and reproducing apparatus according to an embodiment of the present invention during recording, FIG. 2 is a diagram showing the configuration of a magnetic recording and reproducing apparatus according to an embodiment of the present invention during reproduction, and FIG. This figure shows a conventional magnetic recording/reproducing device, and FIG. 4 shows a signal waveform of a non-correlation detection circuit. 1 is a chroma signal, 2 is a comb filter circuit, 3 is a changeover switch, 4 is a band pass filter (BPF), 5 is a converter circuit (CONv), and 6 is a low pass filter (
7 is a mix circuit, 8 is a recording amplifier, 9 is a head, 10 is a tape, 11 is an FM modulator, 12 is a non-correlation detection circuit, 20 is an input terminal, 21 is an IHDlay circuit, 22 is a cyclic addition circuit , 23 is a subtraction circuit, 31 is a capacitor C1, 32 is a coil L, , 33 is a transistor Q
3.34 is the capacitor C1, 35 is the voltage Vl, 36 is the resistor R1, 37 is the resistor R, 38 is the comparator, 39 is the diode D, 40 is the resistor Rs, 41 is the resistor R4, 5
1 is a tape, 52 is a head, 53 is a head amplifier, 54
is a low-pass filter, 55 is a converter, 56 is a band-pass filter, 57 is a comb-shaped filter circuit, 58 is a changeover switch, 59 is an amplifier, 60 is a luminance signal, 61 is a mix circuit, 62 is a video signal, 100 is a magnetic recording/reproduction The circuit 200 is a saturation detection circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) When recording, remove the luminance signal component of the chroma signal.
A comb-shaped filter circuit that removes crosstalk during playback; a non-correlation detection circuit that selects whether to remove the luminance signal component of a chroma signal during recording and crosstalk during playback; and the non-correlation detection circuit. In a magnetic recording/reproducing device, the saturation level of the chroma signal is detected and the chroma signal having a low saturation level is selected based on the output of the chroma signal. The switch is fixed to the side of the comb filter circuit so that the signal passes through the comb filter circuit, and a highly saturated chroma signal passes through the comb filter circuit according to the output of the non-correlation detection circuit, or A magnetic recording/reproducing device comprising a saturation detection circuit that switches and operates the switch so as to bypass the switch.