JPS589485B2 - magnetic playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic reproducing device, and its purpose is to set a reproducing peaking amount suitable for the reproducing head, and to always perform reproduction with the highest performance of the reproducing head. An object of the present invention is to provide a magnetic reproducing device that can automatically adjust the amount of reproducing peaking.

Conventionally, in audio tape recorders, etc., playback equalizer characteristics are uniformly determined by JIS, international standards, etc., but in reality, due to the inherent loss of the playback head, playback peaking is used to compensate for this loss. It is well known that

The amount of reproducing peaking is adjusted by the manufacturer, but as shown in FIG. 1, the amount of loss changes from the initial state due to wear of the reproducing head and other factors as the period of use increases.

Curve A in the figure shows before use, the curve at the beginning shows use for 500 hours, and the curve C shows use for 1000 hours.

Therefore, it can be said that the user always needs to adjust the reproduction peaking amount.

It goes without saying that similar adjustments are required when replacing the reproducing head.

Recently, test tapes that serve as standards for frequency characteristics are available at low cost, allowing users to adjust playback peaking using test tapes.

However, regenerative peaking adjustment requires a high-precision AC voltmeter, and the adjustment location is often located inside the board or otherwise not in an easy location, so it is not common.

Therefore, in many cases, tape recorders were not used at their maximum performance, which was not desirable.

The magnetic reproducing apparatus of the present invention has been developed in view of the above-mentioned problems.

Currently, the frequency regulation signal of commercially available test tapes is recorded as shown in Figure 2. Therefore, first, for example, when reproducing a 400Hz signal, the output voltage is memorized, and when reproducing a 20KHz signal, the same output voltage is recorded. The optimum amount of peaking can be obtained by adjusting the reproduction peaking so that

The present invention takes advantage of this point and will be described in detail with reference to an embodiment shown in FIG.

Now play back the 400Hz portion of A of the test tape in Figure 2.

At this time, the output voltage of the playback head 1 is equalized by the playback equalizer 2,
It passes through the regenerative peaking 3 and reaches the rectifier 6.

At this time, since the reproduction frequency is 400 Hz, the signal voltage has no relation to the amount of reproduction peaking.

The signal rectified by the rectifier 6 is smoothed by a smoothing circuit 7, passes through a buffer amplifier 8, and reaches a contact 9.

By turning on the switch 16, the mono-multivibrator 17 is activated, the relay 18 is excited for a certain period of time, and the signal voltage is stored in the analog memory 19.

Next, the 20 KHz portion B of the test tape in FIG. 2 is similarly reproduced, and at the same time, the switch 12 is turned on.

As with the 400Hz signal, the rectified and smoothed signal reaches contact 10.

By first turning on the switch 12, the mono-multivibrator 13 is activated, the relay 14 is energized, and a signal is sent to the comparator 20 through the contact 10.

Here, it is compared with the previously stored voltage in the analog memory 19, and a difference voltage is output.

This differential voltage is sent to Schmitt trigger 21 and Schmitt trigger 24.

Here, the Schmitt trigger 21 operates with a positive voltage, and the Schmitt trigger 24 operates with a negative voltage.

When the Schmitt trigger 21 or 24 is turned on, the relay 22 or 25 is energized, and the analog memory 2
Charge or discharge the capacitor 30 in 8.

This charging or discharging causes the output voltage of the analog memory 28 to increase or decrease.

At this time, the setting is such that when the output voltage of the analog memory 28 increases, the regenerative peaking amount decreases, and when the output voltage decreases, the regenerative heating amount increases.
The output of 0 converges to zero.

When the output voltage of the comparator 20 reaches zero, the relay 23
and relay 26 are turned off at the same time, contact 23 and contact 26
is turned off, and the reproduction peaking amount is held by the analog memory 28.

After a certain period of time, the contact 27 is turned off in conjunction with the contact 10 to prevent an erroneous difference caused by the audio signal.

The analog memory may be one using a high resistance element (for example, FET) 29 and a low leakage capacitance 30 as shown in FIG. 4, or it may be one in which a potentiometer is driven by a motor.

Furthermore, in the above embodiment, the adjustment point was selected at a point where the output levels of two different frequencies are equal, but the adjustment point may be selected at any point where the level difference is arbitrary, and the number of adjustment signals needs to be limited to two. Instead, multi-point adjustment may be used.

Since the present invention is configured as described above, it is possible to compare the playback outputs of different signals recorded on the test tape and reproduce it with high precision and always with the optimal playback peaking amount, so that the playback head has the ability to It can be used to the best of its ability, and can always be used at peak performance regardless of changes in the playback head over time.Furthermore, adjustments when replacing the playback head are simple, reducing the burden on users and producers. Moreover, since no adjustment by the producer is required, it has the excellent effect of contributing to improved productivity.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing how the frequency characteristics change depending on the usage time of the playback head, Fig. 2 is an explanatory diagram of the recorded contents of the test tape, and Fig. 3 is a circuit block diagram of an embodiment of the present invention.
Figure 4 is a circuit diagram of the same analog memory as above, where 1 is a playback head, 2 is a playback equalizer, 3 is a playback peaking,
19 is an analog memory, and 20 is a comparator.

Claims (1)

[Claims] 1 means for reproducing a signal pre-recorded on a test tape, means for varying the amount of reproduction peaking or frequency, means for storing a reproduction output voltage, and a voltage output corresponding to the stored first signal of the test tape. and means for operating the means for varying the reproduction peaking amount or frequency according to the voltage difference between the reproduction output voltage corresponding to the first signal and the different second signal of the test tape, and the voltage difference is equal to zero. A magnetic reproducing device characterized in that the above-mentioned reproduction peaking amount or frequency is set where appropriate.