JPS60143401A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To increase the quantity of recorded information without increasing the number of magnetic tracks, by recording control signals other than clock signals on the same track of already recorded clock signals under a superposed condition. CONSTITUTION:The section 3 of a magnetic medium is moved in the direction of the arrow 8. On the part 9 of the magnetic substance clock signals 6 are recorded for the whole section of the magnetic substance in the direction of thickness by a sufficiently large recording head current as shown by broken lines. When a control signal current which is different in kind from the clock signal is passed through a winding 12 at a value which is smaller than that when the clock signal is recorded, a residual magnetism 14 is kept only in a section close to the surface of the magnetic layer and the residual magnetism by the clock signal is kept under the same condition in the deep part of the magnetic layer. Therefore, two kinds of signals are recorded on the magnetic medium by forming two layers 14 and 9 in the direction of thickness.

Description

[Detailed Description of the Invention] The present invention relates to a magnetic recording/reproducing device, which records a clock signal in parallel with broadcast information on some tracks of a magnetic medium in ttq, and outputs when all of the clock signals are detected during reproduction. In comparison with other standard numbers, z0 concerning magnetic recording and reproducing devices that accurately control the transfer speed of magnetic media. In addition to the clock signal recorded at the time of recording a program, there was a demand to record signals for controlling the operation of equipment on the same magnetic medium at a later date, resulting in four different cases. When a broadcasting branch station reproduces and broadcasts magnetic media recorded by
Stone using a magnetic medium 3 as shown in the figure. On the magnetic medium, for example, commercial information 4.5 is recorded between the broadcast information 1.2 recorded in stereo, and the t1 clock signal 6 is recorded between the broadcast IH information 1.2.

If you wish to broadcast with only the commercial information changed in the middle of the above-mentioned broadcast information, the broadcast branch station will change the new commercial information between the commercial information 4.5 and the clock signal 6 on the magnetic medium shown in Figure 1. By additionally recording all seven control signals and detecting all of the control signals at the time of playback, a separate magnetic recording/reproducing device is operated and another commercial is sent out. When the broadcast of another commercial comes to an end, the magnetic medium of the original magnetic recording and reproducing device is transferred to the original magnetic recording and reproducing device. By only switching the line output, the magnetic recording and reproducing device can operate continuously without stopping completely,
The clock signal must be constantly reproduced and the magnetic medium transport speed must be controlled accurately to 7#1J, the reason being to maintain the same accuracy of program end time and to maintain synchronization with the VTR device and telecine device. However, since all the magnetic tracks would be added to the stone for recording the seven control signals shown in Figure 1, the spacing between each trunk would inevitably become smaller, which would not only lead to an increase in crosstalk, but also complicate the construction of the magnetic head. It is inevitable that production will be difficult.

The inventiveness was based on this point, and the control other than the above-mentioned clock signal (i.e., the same clock signal that was already recorded) could be done without adding all the magnetic tracks.
Is there a magnetic recording/reproducing device suitable for superimposing and recording data on a track? Figures 2 to 3 provide that the invention is not less than z0.
Let's explain the diagram in detail. In general magnetic recording that uses a ring-shaped magnetic head, it is known that the longer the recording wavelength and the closer the recording head current during recording, the deeper the residual magnetization penetrates in the thickness direction of the magnetic material. The non-invention that is said to have been created by focusing on the key point is shown in Figure 2. 3 shows the cross-section of the magnetic medium, which is transported in the direction of arrow 8. 9 shows the magnetic material part where the clock signal 6, etc. is recorded over the entire thickness of the magnetic material by a sufficiently large recording head current as shown in the figure. 40゛ (The audio 1'H information is on a separate track, that is, at a position shifted perpendicular to the page! The Z1 winding 12, which is composed of an air gap 11, a winding set 12, and a magnetic core 13, is energized with a control signal current of a different type from the clock signal at a smaller value than when all the clock signals are recorded. At this time, the residual magnetization 14 is left only in the part close to the surface of the magnetic layer, and the residual magnetization due to the clock signal is left as is in the deep part of the magnetic layer, that is, the two types of signals are magnetic Two layers 14 and 9 are formed in the thickness direction of the medium to form a recorded form. Therefore, if all the playback heads are used to play back the control signal 14 and the clock signal 9, the control signal 14 and the clock signal 9 can be played back at the same time. Therefore, these can be separated and taken out for appropriate control.

In this case, the residual magnetization of the magnetic bud surface ati of clock pulse number 9 is erased, and the reproduced output is degraded. By turning the output on, the decrease in playback output can be suppressed.

The above is just an explanation of swallow bias magnetic recording, and when recording two types of 1d with a wide AC bias, they can be similarly recorded in a superimposed manner. In this case, the clock signal to be recorded in advance should be recorded with a normal appropriate bias current or a bias current slightly larger than this, and the clock signal to be recorded later should be recorded with a lower bias current. t″
L good. Figure 3 shows the results of measuring the residual magnetization, that is, the playback output, on the magnetic tape after carrying out all of the above methods.
The column shows the signal reproduction output on the horizontal axis, the vertical axis shows the AC bias current value for later recording, and the curve 15 was previously recorded with a bias current of Odb. A clock signal of 600 Hz is recorded later at the point shown by curve 16, superimposed on the control signal of 41.5 kHz, and erased by increasing the bias current, and the reproduced output gradually decreases.
The reproducing power of Z shows normal bias current characteristics and shows a maximum value at bias current Odb. In this example, the bias current value -4 db is 600 Hz and 1.5 K at point Q) (the reproducing output of Z is equal). ) It seems reasonable to select the bias current of the control signal at approximately this point when recording at a later time.

As explained above, according to Misfire J, when recording later signals in addition to the previously recorded Ibo, it is possible to record two or more types of control signals without installing additional magnetic tracks. have a characteristic.

[Brief explanation of drawings]

Fig. 1 is a diagram of a magnetic track pattern on a magnetic medium recorded by a conventional synchronous magnetic recording/reproducing device, Fig. 2 is a schematic diagram showing the principle of non-invention, and Fig. 3 is a curve showing an embodiment of the present invention. In the figure, Z0 3...Magnetic medium 6...Clock signal 9...Magnetic material 10 on which the clock signal is recorded...Fist magnetic head Fig. 1 Fig. 2

Claims (1)

[Scope of Claims] (1)' A first signal with a long wavelength is recorded over the entire thickness direction of the magnetic medium, and a second signal with a short wavelength is recorded along the first signal track with a long wavelength. ' to be superimposed so as to record near the magnetic N1 plane of the magnetic medium.
Magnetic recording and reproducing device. (♀) Recording the first long wavelength signal deeply in the thickness direction of the magnetic layer of the magnetic medium with a large recording head current;
2. What is the difference between recording a signal with a short wavelength on a portion close to the surface of the magnetic layer of a magnetic medium using a small recording head current? A magnetic recording and reproducing device according to claim 1, characterized in that: (3) The first long-wavelength signal is recorded deeply in the thickness direction of the magnetic layer of the magnetic medium with an appropriate bias current or a slightly larger bias current, and the second short-wavelength signal is recorded with the entire normal bias current. 2. A magnetic recording and reproducing apparatus according to claim 1, wherein recording is performed near the surface of a magnetic layer of said magnetic medium using a very small bias current.