JPS6346499B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording rotary body on which magnetic signals for detecting the speed, position, etc. of a record turntable or a tape of a tape recorder are recorded.

2. Description of the Related Art Conventionally, as shown in FIG. 1, a device is known that records magnetic signals at equal intervals on the outer circumference of a turntable, for example. In the figure, the main rotating body B has magnetic powder coated on its circumference and a reference signal recorded on the magnetic powder, which serves as a reference for the magnetic signal. The main shaft K of this main rotating body B is rotated by a drive motor C, and a recording rotating body A such as a turntable is to record a magnetic signal on this main shaft K.
is removably inserted and rotated coaxially with the main rotating body B. In this way, the reference signal detected by the detection head D from the periphery of the magnetic main rotating body is shaped into a square wave through the amplification and limiter circuit F, and further amplified by the amplifier circuit G. A signal shaped into a square wave as described above is applied to the recording head E, and the signal is recorded for one rotation on the magnetic medium coated around the recording rotating body A, such as a turntable, and immediately after that, the recording head Block the signal. In this way, the main rotating body B
The same magnetic signal recorded on the recording medium is recorded on the peripheral portion of the recording rotating body for one rotation.

However, when a signal is recorded one rotation around the periphery of a rotating body to be recorded in this way, the first recorded signal position and the last recorded signal position do not necessarily match, and the first recorded magnetic signal and the last recorded magnetic signal do not necessarily match. This results in the disadvantage that the phases of the magnetic signals generated are different and the recording pitch changes rapidly.

The present invention aims to provide a method for manufacturing a magnetic recording rotating body that can eliminate the above-mentioned drawbacks, and its purpose is to transfer the reference signal detected from the main rotating body to a turntable or the like. The purpose is to perform magnetic recording with high precision on a rotating body to be recorded.

In order to achieve such an object, the method for manufacturing a magnetic recording rotating body according to the present invention reads out a reference signal for speed or position detection recorded on the main rotating body, and rotates the main rotating body in synchronization with the main rotating body. In a method of manufacturing a magnetic recording rotary body in which the reference signal is magnetically recorded on the recording rotary body, the reference signal is applied to the recording head of the recording rotary body while the recording rotary body makes at least one rotation. The signal is applied at a substantially constant level, and thereafter the level of the reference signal is gradually decreased and applied, and the rotation of the recording rotating body is stopped after reaching a level at which magnetic recording is not performed. It is something.

The present invention will be explained below with reference to FIGS. 2 and 3.

Incidentally, the same parts as in FIG. 1 are given the same reference numerals and redundant explanation will be omitted. In this embodiment, a frequency divider circuit H is connected after the amplification and limiter circuit F, and a gain adjustment device I such as a variable resistor controlled by a control circuit J is connected after the frequency divider circuit H.
Connect. The other parts are the same as the conventional example shown in FIG.

The operation of the above configuration will be explained in detail below.
The recording waveform detected by the recording head D from the main rotating body B is shaped into a square wave by an amplification and limiter circuit F, and is applied to a frequency dividing circuit H. The frequency dividing circuit H is used to change the pitch of a waveform to be recorded on the rotating body A to be recorded such as a turntable in accordance with the type of the rotating body A to be recorded such as a turntable. The control circuit J detects that the main rotating body B has rotated one revolution or more, and controls the above-mentioned gain adjustment device I to gradually reduce the recording signal.

FIG. 3 shows the state of the above recorded signal. The waveforms labeled F, H, and I in the figure are the second waveforms, respectively.
In the figure, the output waveforms of the amplification and limiter circuit F, the frequency divider circuit H, and the gain adjustment device I are shown, and T shows the time axis thereof. It is assumed that recording starts from the current time t ₀ , and the detected output from the main rotating body B is made into a square wave by the amplification and limiter circuit F, resulting in an output waveform F. For example, this output waveform F is divided into 2
The frequency is divided by a factor of 1 and the output waveform becomes H. By detecting the rotation of the drive motor C, the control circuit J determines the time when the main shaft K has made one revolution from time _t0 .
It is detected at time _t1 , and the gain of the gain adjustment circuit I is controlled to gradually decrease based on this detection output, so that the gain becomes zero after time _t2 . The period from time t ₁ to _{time t 2} during which such gain attenuation is performed is, for example, a period of time during which the main shaft k rotates once. The output waveform I of the attenuation circuit I passes through the recording amplifier circuit G to become a recording waveform with a level directly proportional to the output waveform I, and this recording waveform is directly applied onto the recording head.

In this way, recording is performed at a normal level until time _t1 , and after time _t1 , a signal whose level gradually decreases is recorded over the previously recorded portion. In this case, the recorded signal does not attenuate much immediately after time t ₁ , so the previously recorded magnetic signal is corrected by the newly recorded slightly attenuated magnetic signal, but as the level of the recorded signal gradually decreases, , the influence of the recorded signal weakens and the time
Almost no correction is made around _t2 , and since no signal is applied to the magnetic head E after time _t2 , the previously recorded magnetic signal remains unchanged without any correction. In this way, the deviation of the recorded signal is gradually corrected between times _t1 and _t2 . Therefore, unlike the conventional method, the recording signal is not abruptly cut off, so there is no effect from clicks, etc. when the signal is cut off, and the magnetic pulses recorded one revolution before are affected by such click noise. do not have. After the recording signal becomes zero in this way, the rotation of the drive motor C may be stopped.

Since the present invention is constructed as described above, the phase difference between the magnetic signals is gradually adjusted between the overlapping portions at the beginning and end of recording, and highly accurate detection signal recording can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional recording apparatus, FIG. 2 is a system diagram of a recording apparatus of the present invention, and FIG. 3 is a diagram showing waveforms of various parts of the recording apparatus of FIG. A is a rotating body such as a turntable, B is a main rotating body, C is a drive motor, D is a detection head, E is a recording head, F is an amplification and limiter circuit, G is a recording amplification circuit, H is a frequency dividing circuit, I is a gain adjustment device, and J is a control circuit.

Claims (1)

[Claims] 1. Manufacture of a magnetic recording rotating body in which a reference signal for speed or position detection recorded on a main rotating body is read out, and the reference signal is magnetically recorded on a recording rotating body that is rotated synchronously with the main rotating body. In the method, the reference signal is applied at a substantially constant level to the recording head of the rotating body to be recorded while the rotating body to be recorded rotates at least once, and thereafter the level of the reference signal is gradually decreased. A method for producing a magnetic recording rotary body, comprising: applying an electric current at a certain level, and stopping the rotation of the recording rotary body after the voltage reaches a level at which magnetic recording is not performed.