JPS58222406A - Erasing method of magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain an erase rate of a full-width erase head with a desired specification, by using a core material having a low magnetic permeability and adopting a single gap structure. CONSTITUTION:The erase rate of the full-width erase head of a VTR is selected at about 25-40dB against the 1kHz of the aural record signal and about 40-50 dB against the low-frequency component of the video signal, and, as a realizing means of the erase rate, a core material having a low magnetic permeability is used and a single gap 10 is adopted. Therefore, the electric power consumption required for the erase system can be reduced when compared with conventional erase systems and the exothermic of the erase head is also moderrated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for erasing signals recorded on magnetic tape in connection with a full-width erase head of a magnetic recording/reproducing apparatus, particularly a home VTR.

Demand for household VTRs has increased significantly in recent years, and small and compact models have been developed to connect TV cameras and use them outdoors.
Many products now feature lightweight and power-saving designs. V
Since the power consumption of a single R is directly related to the lifespan of the battery, technological developments to save power are being actively carried out, and it is no longer rare to find devices of 5W or less.

There are a number of bottlenecks in reducing power consumption, but one of them is the erasure of signals previously recorded on the magnetic deso recorder used for f-recording, just before recording a new signal. There is a system. Here, in order to drive the erasing head with a sufficient current, power of about 0.6 to 1 W is consumed, and this occupies a large weight when viewed from the V i' R of 5 W and the overall lightning power.

Recently, there has been a movement to use metal tapes in VTRs, but since they have a high coercive force, they require a lot of power to erase, and the power required for erasing is more than twice that of conventional tapes, which means that metal tapes are being used for longer and longer periods of time. It becomes a tax.

Here, the erase system of the conventional VTR will be reexamined using FIGS. 1, 2, and 3.

FIG. 1 is a schematic diagram of a magnetic tape running system, in which 1 is a magnetic tape, 2 is a full-width erase head, 6 and 5 are tape guides, 4 is a rotating cylinder, 6 is A, an OE head,
Of these, 61 is a sound erasing head and 62 is a sound/control head.

To explain the operation when recording a signal according to the figure, first, the magnetic tape 1 traveling in the direction shown by the arrow in the figure comes into contact with the blade gap portion of the full-width erasing head 2, thereby being preliminarily inserted into the magnetic tape 1. The signals recorded on the magnetic tape are completely erased over the entire width of the magnetic tape.

Next, the magnetic tape 1 is wound around the rotary cylinder 4 while its height is regulated by tape guides 6 and 5, and a video signal is recorded.

Although this recording method is unprecedented mechanically, electrically, and electrically, it is already known and has no bearing on the essence of the present invention, so the details will be omitted.

After that, the audio signal recording portion of the magnetic tape 1 is erased by the audio erasing head 61, and the audio signal and the control signal for performing precise running and scanning control on the magnetic tape during playback are recorded by the audio/control head 62. .

The second material is the full-width erasing head 2 shown in FIG.
FIG. 6 is a front view of the E head 6. FIG.

The full width erase head 2 consists of a head core 21 with a double gap. The reason for this double gap is to increase the elimination rate.

That is, the erasing rate generally required for a full-width erasing head is about 60 to 65d) 3 for IK)TZ audio signals, which is a relatively strict specification and difficult to achieve without using a double gap.

If a head that satisfies the above specifications is changed to a single-gap core material, shape, etc., the erasure rate will drop to 40 to 45 dB.The configuration of the zero-order ACE head 6 is as follows. The audio cancellation head 61 consists of a head core 611 that also cures double gaps.

This has approximately the same width and height as the audio rad core 621 of the adjacent audio control head 62, and is positioned so as to be in contact with the audio signal recording portion at the upper end of the magnetic tape.

On the other hand, the control rad core 622 is positioned so as to contact the lower end of the magnetic tape.

FIG. 1j143 shows the recording traces left on the magnetic tape 1 by the running system of FIG. 1, where 7 is a video signal, 8 is an audio signal, and 9 is a control signal.

Although there is a full-width erasing head 2 in FIG. 1, the reason why the voiced erasing head 61 is installed is mainly to enable post-recording operation in which only the audio signal is recorded later. By the way, as mentioned above, the driving power of these two erase heads, especially the full width erase head 2, is VT.
I(.

Although it occupies a large part of the overall consumption and power,
Previously, this had a considerable amount of waste. This will be explained.

First of all, the necessary erasure rate for audio signals is 60 to IKHg.
65 dB, but if the audio cancellation head 61 has that performance, the full-width cancellation head does not need that performance.

The required erasing rate of the control signal varies depending on the recording method, but if you are constantly recording in saturation, such as in recent VTRs, you can rely on self-erasing action during recording, and there are no performance specifications for full-width erasing heads. . Regarding the video 1 wall recording signal, based on past reports and our experimental results,
40 dB is sufficient for the low frequency component, and this corresponds to approximately 25 to 40 dBi [IKHg of the audio signal].

Therefore, it is undesirable to provide a full-width erasing head with an erasing rate of 60 to 65 dB for audio signals at IKHz as in conventional VTRs.

Conventionally, due to this excessive performance specification, power consumption in the circuit system increased, expensive rad core materials were used, and the core had a complicated configuration, which caused many problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a necessary and excessive specification for the erasing rate of a full-width erasing head, and to provide a means for realizing this, in order to eliminate the above-mentioned conventional problems.

In other words, the erasing rate of the full-width erasing head is 40 to 50 dB or IK for the low frequency component of the video recording signal.
25 to 4 (ldB,%+8
: Design by closing. In addition, the means to achieve this are to use a core material for the full-width erase head that is easy to process, low-cost, and has lower magnetic permeability than conventional materials, or to use a single-gap core. The aim is to significantly reduce the torsion force, simplify the configuration of the erasing head, and reduce costs.

Examples of the present invention will be described below.

FIG. 4 shows the characteristics of the erase current of the full-width erase head versus the erase rate for a 1 KHz audio signal and the power consumption of the drive circuit.

Of course, these characteristics vary depending on the magnetic tape and erasing head used, and also vary depending on the running speed of the magnetic tape. Therefore, regarding the erasure rate, we have shown an absolute value of 1h as an example, but regarding power consumption, we have normalized the value at 160 mA, which gives an erase rate of 65 dB, as 1, and expressed it as a relative value. , IK, the erasure rate at Hz is 6
Although the power consumption is designed to be 0 to 65 dB, it can be seen that if the power consumption is designed to be 25 to 40 dB as intended by the present invention, the power consumption can be reduced to about half. This is extremely effective in devices such as recent VTRs that require significant power-saving design.

Of course, this still provides a sufficient erasure rate for each recording signal, so there is no performance deterioration associated with this.

To achieve this, while still using the conventional full-width erase head, we lowered the power supply voltage of the oscillation circuit that supplies the erase current to it9, and decreased the number of turns of the transformer that interrupts the oscillation circuit and the erase head. All you have to do is change it, and all of them can contribute to reducing consumption. However, the purpose can also be achieved by further erasing and changing C.

Conventionally, as shown in Figure 2, full-width erasing was performed.

The core 21 of the card has a double-gap structure, so that the I
If a KHz erasure rate of 60 to 65 dB is obtained, or if this can be achieved at 25 to 40 dB as in the present invention, this is not necessary.

FIG. 5 is a front view of a full-width erase head 10 useful in implementing the present invention, which comprises a head core 101 with a single gap.

FIG. 6 is an example in which the erase rate characteristics of erase current versus IKHg are compared between a double gap erase head and a single gap erase head, which are made of the same material and have the same shape tl.

As can be seen from the figure, the maximum erasing rate of the single-gap erase head is about 2° compared to that of the double-gap one.
Although it is dB worse, the required erasure rate is 25 to 40 dB.
If this is acceptable, it can be put to practical use even with a smaller erase current than the conventional one.

As can be easily inferred from a single gap head,
It is easier to manufacture and process than a double gap head, and can contribute to reducing manufacturing costs. In addition, since the gap is in one place, the tape only needs to make contact with the magnetic cheese at a single point when running, so there is more freedom in designing the running system compared to the conventional case where contact must be made at the sliding point. In addition, the head itself can be made smaller, which can also contribute to role 1 of a small VTR.0 In addition, as a means of responding to changes in erase rate specifications, we have developed a core with lower magnetic permeability than before. It is also possible to use detergent.

Conventionally, ferrite materials have been commonly used as core materials for erase heads, and materials with a celadon coefficient of as high as 1000 at high frequencies have been used, particularly for magnetic tapes with high coercive force such as metal tapes.

This was not advantageous in terms of manufacturing the core material, processing, and price, but according to the present invention, such a material is no longer necessary, and it facilitates manufacturing and processing. This can contribute to cost reduction.

In addition to describing the embodiments above, we have also touched on its effects, the greatest of which is the reduction in power consumption.

This also has the effect of eliminating the heat generation phenomenon during use, which has often been a problem with conventional erasing heads.

As described above, the present invention increases the erasing rate of the full-width erasing head at V'I'R, to approximately 25 to 40 dB for 1 KHz of audio recording signals, and 40 dB for low frequency components of video recording signals. ~50 dB, and the means to achieve this are to use a low magnetic permeability core material, adopt a single gap structure, etc.

As a result, the power consumption required for the erasing system can be significantly reduced to about half, for example, contributing to the power-saving design of the VTR, and at the same time, the problem of heat generation in the erasing head is alleviated. Furthermore, by using a material with low magnetic permeability, the manufacturing process of the head becomes easy and the cost can be reduced. Furthermore, if a single-gap structure is realized, it will be possible to simplify the manufacturing process of the head, reduce its external size, and increase the degree of freedom in designing the tape running system.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the tape running thread of a VTR, Figure 2 is a front view of the full-width erase head and AOE head, Figure 3 is a diagram of the recording pattern on the magnetic tape, Figure 4 is a diagram of the erase characteristics of the erase head, and Figure 4 is a diagram of the recording pattern on the magnetic tape. Figure 5 is a front view of the full width erasing head used in the present invention;
FIG. 6 is an erase characteristic diagram of two types of erase heads. 10...Full-width erase head 101...Erase head core agent Susuki 1) Ri, Kosai IWJ 2 Figure 3 Moon 1'4 Figure 5 8) OI Δ

Claims (1)

[Claims] A magnetic recording/reproducing device equipped with a full-width erasing head for erasing signals previously recorded on the magnetic tape to be used over the entire width thereof, and a conventional audio erasing head for erasing only the portion of the magnetic tape where audio signals are recorded. In the device,
A magnetic recording/reproduction device characterized in that the erasing rate of the full-width erasing head is set to about 25 to 40 dB at a frequency of 1 KHz of a recorded audio signal, or about 40 to 50 dB at a low frequency of a recorded video image signal. How to erase the device.