JPH01161989A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve a luminance signal S/N and a chrominance signal S/N by providing a couple of FM luminance signal reproduction exclusive head with narrow gap and a couple of recording and chrominance signal reproduction heads with a wide gap. CONSTITUTION:Magnetic heads 15, 16 in pairs recording a signal synthesized with a low frequency chrominance signal and an FM luminance signal and reproducing mainly a low frequency chrominance signal, and magnetic heads 19, 20 reproducing mainly the FM luminance signal with a narrow gap are provided to the device. That is, the heads 15, 16 with a wide gap are used as the recording head at recording to avoid magnetic saturation of the low frequency area and the recording heads 15, 16 with a wide gap are used to reproduce the chrominance signal at reproduction thereby improving the response of the low frequency and the heads 19, 20 with narrow gap are used to reproduce the FM luminance signal thereby improving the high frequency characteristic.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording/reproducing device, and relates to a signal-to-noise ratio of a chrominance signal and a luminance signal in a system that records chrominance signals and luminance signals by frequency division multiplexing. It is related to the improvement of

[Prior Art] Although the present invention can be widely applied to magnetic recording and reproducing apparatuses that record video signals by frequency division multiplexing, the following description will be given using a home VTR as an example.

FIG. 7 is a diagram showing the frequency arrangement of the FM luminance signal low frequency conversion color signal, which is the VH3 standard in the NTSC system. FIG. 8 is a block circuit diagram of a conventionally used two-head type recording/reproducing circuit.

First, the operation during recording will be explained. In FIG. 8, the FM luminance signal is supplied to the terminal (1), and the low frequency conversion color signal is supplied to the terminal (2). The signals supplied to the terminals (+) and (2) are combined by an adder circuit (3). The frequency spectrum of the output signal of the adder circuit (3) is as shown in FIG. The output signal from the adder circuit (3) is supplied to the recording amplifier (4), where it amplifies the voltage and current enough to drive the rotary transformer system at the subsequent stage.

The output signal of the recording amplifier (4) is transmitted through a rotary transformer (5).
), the current is supplied to the common terminal of the primary windings (5a) and (5b) of the rotary transformer (5). (13) is opened, and switches (s) and (7) are closed to short-circuit to ground. Next, the secondary winding (5c) of the rotary transformer (5), (5
d) The signal induced in the magnetic head (8), (
9) and recorded on the magnetic tape (!0).

The reason why two magnetic heads are required here is that one magnetic head is in charge of one field of the video signal, and two magnetic heads are mounted 180 degrees opposite each other on the rotating drum, as shown in Figure 9.
This is because it is a so-called two-head helical scan system in which one magnetic head records one frame of the video signal on two tracks CHI and CH2.

Next, the operation during playback will be explained. Contrary to when recording, the signals recorded on the magnetic tape (10) are converted into voltage by the magnetic heads (8) and (9).

The head amplifier (1) is connected via the rotary transformer (5).
1) and (12) respectively, and the switches (8) and (7) are opened so that the output signal of the rotary transformer (5) is induced between the grounds, and the switch (1)
3) is controlled to close and short-circuit to ground. The output signals of the head amplifiers (11) and (12) are
The signal is supplied to a changeover switch (14), which is switched and controlled by a signal indicating the rotational phase of the drum, and output as a continuous reproduction signal from a terminal (30).

Incidentally, the gap interval is an important parameter that influences the characteristics of a magnetic head.

Figure 10 shows the recording and reproduction characteristics when the gap length is widened and narrowed.As can be seen from Figure 0, the reproduction frequency characteristics change significantly depending on the gap length, and the optimum gap length for low-range color signals. The optimal gap length for FM frequency signals is different.

[Problems to be Solved by the Invention] As mentioned above, in a conventional magnetic recording/reproducing device that records a low frequency color signal and an FM luminance signal by frequency division multiplexing and reproduces the signals using the same magnetic head as the recording head, The problem is that the optimal gap length cannot be selected for each of the low-range color signal and the FM luminance signal, so the chrominance signal S/N and luminance signal S/N are insufficient, and the characteristics of the magnetic tape cannot be fully brought out. was there.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic recording/reproducing device that can significantly improve the brightness signal S/N and color signal S/N.

[Means for Solving the Problems] The magnetic recording and reproducing device according to the present invention has a low frequency color signal and an F
A magnetic head pair with a wide gap length for recording a signal synthesized with an M luminance signal and mainly reproducing a low-range color signal, and a magnetic head pair having a narrow gap length for mainly reproducing an FM luminance signal. It is characterized by having the following.

[Function] In the present invention, during recording, a head with a wide gap length is used as a recording head to eliminate magnetic saturation in the low frequency range, and during reproduction, the above recording head with a wide gap length is used to reproduce color signals. The low frequency response is improved and a head with a narrow gap length is used to reproduce the FM luminance signal to improve high frequency characteristics.

[Example] An embodiment of the present invention will be described below.

FIG. 1 is a block circuit diagram of one embodiment of the present invention.
The same reference numerals as in the figure indicate the same or corresponding parts, (1
5), (18) are magnetic heads with relatively wide gap length, (17), (18) are magnetic heads (15)
.

(16) A head amplifier that amplifies the playback signal, (19)
.

(20) is a magnetic head with a narrow gap length, (5e)
, (5D, (5g), (5h) are rotary transformers (
5) primary and secondary windings, (21) and (22) are head amplifiers that amplify the reproduction signals of the magnetic heads (19) and (20), and (23) is a control synchronized with the rotational phase of the rotating drum. This is a switch that can be switched in conjunction with the switch (14) by a signal.

Next, the operation during recording will be explained.

The FM luminance signal input to the terminal (1) is combined with the low-range color signal supplied to the terminal (2) in an adder circuit (3).

The output signal of the adder circuit (3) is supplied to a recording amplifier (4), where both voltage and current are amplified. The output signal of the recording amplifier (4) is sent to the negative winding (5a) of the rotary transformer (5).
), (5b) are supplied to the common terminal. At this time,
Open switch (13), switch (6), (7
) is closed and shorted to ground, and the current from the common terminal is controlled to flow to ground through switches (6) and (7). Signals induced in the secondary windings (5c) and (5d) of the rotary transformer (5) are transferred to two magnetic heads (15) with a wide gap mounted opposite each other on a rotating drum.

(16) and recorded on a magnetic tape (lO).

In this way, a magnetic head with a wide gap length.

When (15) and (1B) are used for recording, the magnetic head becomes less likely to be magnetically saturated, so it is possible to significantly reduce the tertiary type of the electromagnetic system, which has a large effect on the upper limit of the recording current of color signals. Therefore, since the recording level of the low-range color signal can be increased, the color signal S/N can be improved. Furthermore, since the recording efficiency of the magnetic head is improved, the number of recording Q'N flows is reduced, and the load on the recording amplifier (4) is also reduced.

Next, changes in reproduction frequency characteristics depending on the width of the gap of the magnetic head will be explained.

FIG. 2 is a recording/reproducing frequency characteristic diagram when the gap length is changed. The characteristic curve a in the figure shows the characteristics of a magnetic head with a narrow gap length, and the characteristic curve is the characteristic surface l! ;ja shows the characteristics of a magnetic head with a wider gap length. Further, FIG. 3 is a recording/reproducing frequency characteristic diagram including the function -F of the magnetic head, and the characteristic curve a is the characteristic curve 4 of the magnetic head with a narrow gap length. The characteristic curve shows the characteristics of a magnetic head with a wide gap length. As can be seen from FIG. 3, the narrower the gap length, the better the high frequency response, and conversely, the wider the gap interval, the better the low frequency response.

In this embodiment, in consideration of matching with recording characteristics, magnetic heads (15), (+6) with wide gap lengths are used as reproduction heads for low-range color signals, and magnetic heads (19), (+6) with narrow gap lengths are used as reproduction heads for low-range color signals. 20) is used as a reproducing head for high frequency FM luminance signals.

Next, the operation during playback will be explained.

The output signals of the magnetic heads (15) and (113) are sent to the head amplifier (17) through the rotary transformer (5).
, (18), amplified to a desired signal level, and further supplied to a changeover switch (14). The changeover switch (14) is controlled by a changeover signal synchronized with the rotational phase of the rotating drum, and outputs an intermittent color signal every 180 degrees as a continuous color signal from an output terminal (30).

On the other hand, the FM quality signals reproduced by the magnetic heads (19) and (20) are supplied to the head amplifiers (21) and (22) via the rotary transformer (5), similar to the color signals, and are boosted to a predetermined level. After being amplified, it is converted into a continuous FM luminance signal by a changeover switch (23) and output from a terminal (4o).

Figure 4 shows the recording/reproducing frequency characteristics of this embodiment and the recording/reproducing frequency characteristics of a commonly used conventional magnetic head with an intermediate gap length. Characteristics of the reproduced color signal recording/reproducing system are shown as wide-gap recording and luminance signal recording/reproducing system of narrow-gap reproduction.Characteristic C is the recording/reproducing characteristic of a conventional VTR. . From this characteristic diagram, it can be seen that in this embodiment, the S/N of the low frequency chrominance signal and the S/N of the high frequency FM luminance signal can be significantly improved compared to characteristic C of the conventional magnetic head.

As shown in Fig. 5, when there are multiple modulation modes with different carrier frequencies of the FM luminance signal, the mode with a higher carrier frequency uses a different type of magnetic tape with better magnetic properties than the mode with a lower carrier frequency. may be used. 6th
The figure shows an example of the characteristics of a magnetic tape. In such a case, a magnetic head with a narrow gap length is used due to the requirements of a system with a high carrier frequency.

Therefore, in a magnetic recording/reproducing device having a plurality of modulation modes, recording/reproducing characteristics of color signals deteriorate in the modulation mode with a low transmission frequency in the conventional magnetic recording/reproducing device. Optimal recording and playback performance is achieved even for the following modulation modes.

[ ); P:, Bright effect] As described above, according to the present invention, a pair of heads dedicated to reproducing FM luminance signals with a narrow gap length, and a pair of heads dedicated to reproducing FM luminance signals with a wide gap length, and a pair of heads with a wide gap length for recording and color signal reproduction are provided. During recording, the third-order distortion due to magnetic saturation of the color signal can be reduced, increasing the recording forward current, and the head efficiency is improved, reducing the load on the recording amplifier. In some cases, the frequency characteristics of the chrominance signal band can be improved by using the recording head as a chrominance signal reproduction head, and the response of the FMIII signal band can also be greatly improved by using a brightness signal reproduction narrow gap head. .

Further, even in a magnetic recording/reproducing apparatus having a plurality of modulation modes in which the carrier frequency of the FM signal is different, optimal recording and reproduction can be performed for any modulation mode.

Furthermore, even high-performance tapes can be filled with the wide gap head.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between the gap length of the magnetic head and the t21+ reproduction frequency characteristics, and Fig. 3 is a diagram showing the relationship between the magnetic head's performance and rate. Figure 4 shows the recording/reproducing characteristics of this embodiment and the recording/reproducing characteristics of a conventional magnetic recording/reproducing device. Figure 5 shows the recording/reproducing characteristics of a system with two modulation modes. FMlii 1 degree signal 9 A diagram showing an example of the frequency arrangement of the color signal, FIG. 6 is a diagram showing an example of the characteristics of a magnetic tape, FIG. 7 is a frequency arrangement diagram of the luminance signal and chrominance signal of the recording signal in the NTSC system, and FIG. The figure is a block circuit diagram of the recording/reproducing system of a conventional VTR, Figure 9 is a diagram showing the track pattern in the two-head helical scan system, and Figure 10 is the relationship between the gap length and recording/reproducing frequency characteristics of a conventional magnetic head. It is a characteristic diagram showing a relationship. (5)...Rotary transformer, (15), (l
e) Recording head/color signal reproducing head, (19)
, (20)... Luminance signal reproducing head. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A magnetic recording and reproducing device that performs frequency modulation on the luminance signal of a color television signal to be recorded, and performs frequency division multiplexing on the lower frequency side of the FM luminance signal to record the color signal, which is a frequency division multiplexed signal. The present invention is characterized by comprising a magnetic head with a wide gap length for recording FM luminance signals on a magnetic recording medium and reproducing color signals from the recording medium, and a magnetic head having a narrow gap length for reproducing FM luminance signals from the recording medium. Magnetic recording and reproducing device.