JPH02278501A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate necessity for switching a recording current for each mode and tape by forming the crossover of the optimum recording current for first and second metal tapes at the midpoint of a carrier center for the normal mode and high band mode. CONSTITUTION:By a method such as changing the thickness of a magnetic layer in the tape, the crossover is formed in 6MHz to be the midpoint between 5MHz, which is the carrier center of the normal mode, and 7MHz which is the carrier center of the high band mode in the frequency character of MP and ME tape. When the optimum recording current in this 6MHz is made flow from a recording amplifier 8 to a head 9 as the set recording current, the recording current can be one type of the unified current even in either the normal mode or high band mode and even for either the MP tape or ME tape. Accordingly, circuit configuration can be simplified.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to a so-called magnetic tape in which a video signal is recorded on or reproduced from a magnetic tape having a tape width of 8 mm, for example. The present invention relates to a magnetic recording and reproducing device suitable for use in 8 mm video tape recorders and the like.

[Summary of the invention]

The first aspect of the present invention is to form an optimal recording current crossover of the first metal tape and the second metal tape at an intermediate point between the carrier centers of the first mode and the second mode, and to adjust the recording current at this crossover. By eliminating the switching of the recording current, it becomes unnecessary to switch the recording current for each mode and for each tape, thereby simplifying the circuit configuration.

Further, in the second aspect of the present invention, a crossover of the optimum recording current of the first metal tape and the second metal tape is formed at the carrier center in the first mode or the second mode, and the recording current at this crossover is By discontinuing switching, it becomes unnecessary to switch the recording current for each tape in the first mode or the second mode, thereby simplifying the circuit configuration.

[Conventional technology]

Generally, the frequency allocation in the normal mode of an 8 mm VTR is done as shown in Figure 5, where Y is the FM luminance signal and C is the low frequency conversion color signal (
743,44kHz), AFM is an audio FM signal (1,5MHz). The carrier center of the FM brightness signal is at 5MHz, and the synchronization signal peak value is 4.2M.
Hz.

The white level peak value is at 5.4 MHz.

On the other hand, a so-called high-band mode has been proposed in order to widen the band of the luminance signal, increase the horizontal scanning line to 400 or more, improve the horizontal resolution, and improve the image quality. Figure 6 shows the frequency allocation. Although the frequencies of the low-frequency conversion color signal C and the audio FM signal AFM are the same as in the normal mode, the carrier center of the FM luminance signal is 7MH.
z, the synchronization signal peak value is 5.7 MHz, and the white level peak value is 7.7 MHz, which are different from the normal mode.

The recording currents in such normal mode and high band mode are set to optimal recording currents (ORC) of 5 MHz and 7 MHz, respectively.

In addition, in order to ensure that the magnetic tape used for 8 mm VTR does not lack high frequency characteristics, coated metal tape (hereinafter referred to as MO tape) or vapor deposited metal tape (hereinafter referred to as ME tape) is used. ) may be used. In order to distinguish between the two types, one of the five ignition holes is normally drilled in a part of the tape cassette so that it becomes a recess or a through hole, depending on the type. There is.

The frequency characteristics of the MP tape and the ME tape are as shown in FIGS. 7 and 8, respectively, and the two are different.

Note that Japanese Patent Laid-Open No. 810/1983 describes setting the recording current depending on the type of tape.

[Problem to be solved by the invention]

By the way, as mentioned above, in the case of <8 mm VTR, there are two modes, normal mode and bi-band mode, and two types of tape are used, MP tape and ME tape, so when considering the recording current setting, If each recording current is adjusted to the optimum recording current, four types of settings are required, resulting in disadvantages such as troublesome adjustment switching and a complicated circuit.

The present invention has been made in view of this point; in the first invention, such switching can be made unnecessary in any mode, and in the second invention, the first mode which is the normal mode or the bi-band mode can be switched. The object of the present invention is to provide a magnetic recording/reproducing device that can eliminate the need for such switching in a second mode.

[Means to solve the problem]

The first aspect of the present invention is to form an optimal recording current crossover of the first metal tape and the second metal tape at an intermediate point between the carrier centers of the first mode and the second mode, and to adjust the recording current at this crossover. This is a magnetic recording/reproducing device characterized in that the switching of the magnetic field is stopped.

The second aspect of the present invention is to form an optimal recording current crossover between the first metal tape and the second metal tape at the carrier center in the first mode or the second mode, and to switch the recording current at this crossover. This is a magnetic recording and reproducing device characterized in that it is designed to stop recording.

[Operation] The carrier center of the FM luminance signal in the first mode, normal mode, is 5 MHz, and the carrier center of the FM luminance signal in the second mode, high band mode, is 7 MHz. Therefore, in the first invention, the first metal tape MP tape and the second metal tape ME
Form an optimal recording current crossover for the tape (second
figure).

The optimum recording current at this crossover point is then set as the recording current in each mode. This eliminates the need to switch the recording current for each mode or tape, and the circuit becomes simple.

In addition, in the second invention, the first mode or the second mode carrier center, that is, the first
An optimum recording current crawlover is formed between the MP tape, which is the second metal tape, and the ME tape, which is the second metal tape (FIGS. 3 and 4).

Then, the optimum recording current at this crawlover is set as the set recording current in the first mode or the second mode, respectively.

As a result, in the case of the first mode (normal mode) in which a crossover is formed at 5 MHz, in the second mode (biband mode) it is necessary to set the recording current according to the MP tape and ME tape, respectively. In the first mode, M
P tape M' E -r -7' 5M in case of misalignment
The optimum recording current at the point where Hz has crawled over may be used as the set recording current, eliminating the need to switch the recording current for each tape in the first mode, and simplifying the circuit configuration.

In addition, on the contrary, the second waveform that formed a crossover at 7MHz
In the first mode, it is necessary to set the recording current for MP tape and ME tape, but in the second mode, the recording current is 7MHz for both MP tape and ME tape.
The optimum recording current at the crossover point may be used as the set recording current, eliminating the need to switch the recording current for each tape in the second mode, and simplifying the circuit configuration.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 1 to 4.

FIG. 1 shows the circuit configuration of this embodiment. In the figure, (1) is a tape cassette in which a magnetic tape (MP tape or ME tape) is stored. (2) is an ignition hole provided in the cassette (1), and depending on the type of tape (coating type or vapor deposition type), the five holes are recessed or completely transparent. Made with holes. (3) is a device for identifying the tape type, etc., which faces or is in contact with the ignition hole (2) when the tape cassette is installed in the magnetic recording/reproducing device, and which hole is recessed or transparent. It is configured to detect whether a hole has been formed. This identification device (3) can be constructed by having a light receiving element (4) facing each hole and applying light from the other side. (5) represents each of these light receiving elements (
4) This is a determination circuit that determines the type of magnetic tape based on the combination of light reception.

(6) is a changeover switch for manually selecting a normal mode as a first mode and a high band mode as a second mode. (The input terminal is a video signal input terminal, and the video signal applied thereto is supplied to the recording amplifier (8), amplified, and supplied to the next stage rotating magnetic head (9).
recorded on magnetic tape.

Figures 2 to 4 show how to set the recording current. In the example in Figure 2, for example, by changing the thickness of the magnetic layer of the tape, the frequency characteristics of the MP tape and the frequency characteristics of the ME tape are set. 5MHz is the carrier center of normal mode (1st mode) and biband mode (2nd mode)
6MHz, which is approximately midway between 7MHz, which is the carrier center of
A crossover is formed near z.

Then, using this optimum recording current (ORC) at 6 MHz as the set recording current, the recording amplifier (8) sends the head (9)
If the current is applied to the recording current, one type of recording current can be used for both normal mode, bi-band mode, MP tape, and ME tape.

Therefore, in this case, the circuit configurations (1) to (6) in FIG. 1 are also unnecessary, resulting in an extremely simple circuit configuration.

In the example shown in FIG. 3, for example, the thickness of the magnetic layer of the tape is changed so that the frequency characteristics of the MP tape and the frequency characteristics of the ME tape form a crossover at the normal mode carrier center of 5 MHz.

When in normal mode, the mode is set to normal mode using the selector switch (6), regardless of the tape type judgment signal from the judgment circuit (5), that is, in the case of either MP tape or ME tape, when the frequency is 5MHz. If the optimum recording current is set as the set recording current and is passed from the recording amplifier (8) to the head (9), one type of unified recording current can be used for both MP tape and ME tape.

On the other hand, when in high band mode, the mode is set to biband mode using the selector switch (6), and the optimum recording current suitable for MP tape or ME tape is set depending on the tape type judgment signal from the judgment circuit (5). The set recording current is made to flow from the recording amplifier (8) to the head (9).

Therefore, in bi-band mode, it is necessary to switch the recording current depending on the MP tape and ME tape, but in normal mode, the same recording current can be used for MP tape and ME tape, and it is not necessary to switch between tapes. Therefore, the circuit configuration can be simplified accordingly.

In the example shown in FIG. 4, for example, the thickness of the magnetic layer of the tape is changed so that the frequency characteristics of the MP tape and the frequency characteristics of the ME tape form a crossover at the carrier center of the biband moat at 7 MHz.

And when in high band mode, switch switch (6)
The mode is set to bi-band mode, and the optimum recording current at 7 MHz is recorded as the set recording current regardless of the tape type judgment signal from the judgment circuit (5), that is, for either MP tape or ME tape. If the current is passed from the amplifier (8) to the head (9), one type of recording current can be used for both MP and ME tapes.

On the other hand, when in normal mode, the mode is set to normal mode with the changeover switch (6), and the optimum recording current suitable for MP tape or ME tape is set respectively according to the tape type judgment signal from the judgment circuit (5). The recording current is made to flow from the recording amplifier (8) to the head (9).

Therefore, in normal mode, it is necessary to switch the recording current depending on the MP tape and ME tape, but in bi-band mode, the same recording current can be used for MP tape and ME tape, and switching is not necessary for each tape. Therefore, the LJ circuit configuration can be simplified.

〔Effect of the invention〕

As described above, according to the first aspect of the invention, the optimum recording currents of the first metal tape and the second metal tape are matched at a predetermined frequency, and the optimum recording current at this predetermined frequency is adjusted to the first mode and the second mode. Since the recording type current is set for each mode, there is no need to switch the recording current for each mode and each tape, and the circuit configuration is simplified.

Further, according to the second aspect of the present invention, the optimum recording current of the first metal tape and the second metal tape is set to the first mode or the second mode.
Since the recording current in the first mode or the second mode is set to the optimum recording current at this carrier center, the recording current for each tape in the first mode or the second mode is matched. There is no need to switch the recording current, and the circuit configuration is simplified.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing one embodiment of the present invention, FIGS. 2 to 4 are diagrams for explaining the operation of the present invention, and FIG.
6 and 6 are diagrams showing the frequency allocation of the normal mode and high band mode of an 8 mm VTR, respectively, and FIGS. 7 and 8 are diagrams showing the frequency characteristics of the MP tape and the ME tape, respectively. (1) is the tape force center, (2) is the ignition hole, (3) is the identification device, (5) is the judgment circuit, (6) is the changeover switch, (8) is the recording amplifier, and (9) is the rotating magnetic head. It is.

Claims (1)

[Claims] 1. An optimal recording current crossover of the first metal tape and the second metal tape is formed at an intermediate point between the carrier centers of the first mode and the second mode, and recording is performed at the crossover. A magnetic recording/reproducing device characterized in that switching of current is stopped. 2. At the career center in the first mode or the second mode,
1. A magnetic recording and reproducing apparatus characterized in that a crossover of optimum recording currents is formed between a metal tape and a second metal tape, and switching of recording current at the crossover is stopped.