JPS624765B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting recording characteristics of a tape recorder, and particularly to adjusting recording characteristics such as recording level, bias, and compensation amount (equalizer) to optimum values in a tape recorder having a recording/playback head. Regarding the adjustment method.

Although there are various types of magnetic recording tape, each tape recorder is usually tuned with a standard tape for each type of tape. However, since tapes of the same type have different characteristics, it is necessary to adjust the recording characteristics for each tape.

When adjusting the recording characteristics of a so-called two-head tape recorder that has a dual-purpose recording/playback head, first record the adjustment signal onto the tape while varying the level, bias, EQ (equalizer) compensation amount, etc. After that, the tape is rewound and the adjusted signal is reproduced, and the optimal level, bias, compensation amount, etc. are adjusted based on the level of the reproduced signal. Then, after the adjustment is completed, rewinding is performed again to restore the original state, and the adjustment is completed.

That is, each step of adjusting the recording level, recording bias, and recording compensation amount requires recording, rewinding, playback, and rewinding steps, which is not only complicated but also requires a long time for adjustment.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an adjustment method capable of adjusting recording characteristics such as level, bias, and compensation amount in a short time and efficiently.

A method for adjusting recording characteristics of a tape recorder according to the present invention includes sequentially changing one of the recording level, recording bias, and recording compensation amount while running the magnetic tape in one direction, and recording an adjustment signal on the magnetic tape for a predetermined period. The present invention is characterized in that the recording characteristics are then adjusted by detecting the reproduction level of the adjustment signal while running the magnetic tape in the opposite direction.

The present invention will be explained below using the drawings.

FIG. 1 shows a schematic plan view of a tape running system illustrating an embodiment of the present invention, in which A shows the recording state of the adjustment signal and B shows the playback state of the adjustment signal.
In A and B, 10 is a recording/playback head;
11 is a magnetic tape, 19 and 20 are tape reels, 21 and 22 are erase heads, and 23 and 2 are tape reels.
4 indicates a capstan, and 25 and 26 indicate pinch rollers, respectively. In this example, a tape recorder is equipped with a so-called auto-reverse function capable of forward and reverse running playback. First, as shown in Figure A, an adjustment signal is recorded by the head 10 for a predetermined period while the tape 11 is running rightward. do. At this time, the right pinch roller 26 contacts the capstan shaft 24 and travels in the right direction, and one of the recording level, recording bias, and recording compensation amount is sequentially changed and an adjustment signal is recorded.

Next, as shown in Figure B, pinch roller 2 on the left
5 contacts the capstan shaft 23, and the tape 11 runs to the left. At this time, the adjustment signal is played back by the head 10, and since this playback signal level changes sequentially depending on the level, bias, or compensation amount during recording, the optimum recording condition is detected using this playback level. Ru. In auto-reverse type tape recorders, the head generally moves during reverse playback (running in the left direction) and plays back a different track from the tape track when the tape is running in the forward direction (running right). However, since it is necessary for the head to slide on the same track in both the forward and reverse travel directions during adjustment, the head is controlled to be prohibited from moving.

By doing this, each adjustment of the recording level, bias, and compensation amount can be done in twice the recording time of the adjustment signal (one round trip time required for recording and playback), which is shorter than the conventional adjustment time. Half would be a good thing.

FIG. 2 is a plan view illustrating another embodiment of the present invention, showing the case of an ordinary tape recorder without an auto-reverse function, and parts equivalent to those in FIG. 1 are designated by the same reference numerals. First, as shown in Figure A, while the tape 11 is running in the right direction, the adjustment signal is recorded by the head 10 for a predetermined period while changing the level, bias, compensation amount, etc. Next, as shown in Figure B, while the tape 11 is running to the left, the head 10 plays back the adjustment signal and detects the optimum recording condition based on the playback level.On the left side of the head 10 is a pinch roller and a capstan mechanism. Because the tape is not provided with a
Although flutter and the like will be worse, it can be fully used for practical purposes during adjustment. It goes without saying that the capstan motor that drives the capstan shaft 24 should be designed to be able to rotate in forward and reverse directions using a mechanism similar to that of an auto-reverse machine so that reverse running regeneration is possible.

FIG. 3 is a block diagram of an adjustment device suitable for use in the adjustment method of the present invention, in which two frequencies ₁ (400Hz) and ₂ are used as signals for adjusting recording characteristics.
(10KHz) frequency signal is used. The middle and low frequency signal ₁ is applied as is to the gate circuit 1 having the transistor _Q1 , and the high frequency signal ₂
is applied to the movable terminal of the characteristic adjustment switch _S2a . The three fixed contacts of this switch _S2a are the recording level, recording EQ (compensation amount), and recording bias contacts, and the level contact is open and the EQ
and bias contacts are commonly connected to gate circuit 1
connected to. Therefore, when adjusting the recording level, only signal ₁ is input to line amplifier 2 via gate circuit 1, and when adjusting recording EQ and recording bias, signals ₁ and ₂ are superimposed and input to line amplifier 2 via gate circuit 1. becomes.

Oscillation pulse 3 of unstable multivibrator 3 for controlling transistor Q ₁ of gate circuit 1
is used, and this pulse becomes the base input of the transistor Q ₁ via the resistor R ₁ and the counting input of the up-down counter 4 via the diode D ₁ . The count output of the up-down counter 4 is applied to the decoder 5 and the switch
Via _S1 , it is applied to a selection switch _S2b which selects the type of recording characteristic to be adjusted. The settings of the recording level setting circuit 6, the recording EQ setting circuit 7, and the recording bias setting circuit 8 are controlled by the output of each contact of this switch _S2b . The carry output of the counter 4 serves as a stop signal for the multivibrator 3 as well as a control signal for the mechanical system, and the output from the mechanical system is used as an up/down command signal for the counter 4.

Therefore _, by generating the control signal from the multivibrator 3 at regular intervals as shown in _FIG . The signal has a waveform as shown in FIG. 4B, in which the signal is periodically turned on and off. During level adjustment, only signal ₁ is periodically turned on and off and output. Each of the setting circuits 6, 7, and 8 is configured to be able to control the recording level, EQ, and bias amount in accordance with the output content of the decoder 5, that is, the count content of the counter 4. Therefore, the level, EQ and bias amount of the output signal of the line amplifier 2 are suitably controlled and recorded by the head 10 onto the tape 11 which is a recording medium.

Regarding the reproduction system, the signal reproduced from the head 10 is amplified by a reproduction amplifier 13 and separated into frequency signals ₁ and ₂ by a signal separation circuit 14. Both separated outputs are rectified and smoothed by circuit 1.
5 and 16, it is converted to a DC level and applied to a comparator 17. This comparator is configured to generate, for example, a high level signal when the DC output levels of both signals become equal, and this signal becomes the set input of the flip-flop 30. This flip-flop 30 is inverted by the high level signal of the comparator 17 and controls the switch _S1 to be open, so that the output of the decoder 5 is not transmitted to each setting circuit 6-8.

In addition to the rectifying and smoothing circuit 16 for the frequency signal ₂ , the reference voltage E is also input via the recording characteristics switch _S2c .
is applied, and this voltage is input only when adjusting the level. Further, the DC output of the rectifying and smoothing circuit 15 is shaped into a pulse signal as shown in FIG.

A case will be described in which the recording EQ characteristics of the tape recorder are adjusted in such a configuration. When the switches S _2a to _{S 2c} are switched to the recording EQ side to enter the recording state, the reset input to the counter 4 and multivibrator 3 from the main body of the device is released, the multivibrator 3 oscillates, and this oscillation pulse (Fig. 4A), the counter 4 starts counting in the positive direction, and as shown in Fig. 4B, ₁ +
_Two superimposed signals are periodically recorded on the tape 11. At this time, the recording equalizer setting circuit 7 sequentially adjusts the level according to the count contents of the counter 4. This state is shown in Figure 1 A or Figure 2 A.
It is in a state of When the counter 4 finishes counting a predetermined number of times, a carry output is generated to stop the oscillation of the multivibrator 3 and to cancel the recording state of the device. At the same time, the mechanical system is controlled to be in a reverse running state and also to be in a regeneration state. This state is the state shown in FIG. 1B or FIG. 2B.

When regeneration is performed, both signals are separated by the separation circuit 14, and DC levels corresponding to the levels of the signals ₁ and ₂ are obtained from the circuits 15 and 16, respectively.The comparator 17 compares these levels and determines that they match. When this occurs, flip-flop 30 is reversed and switch _S1 is opened. During this playback period, the counter 4 is controlled to count down, and the pulse output of the waveform shaping circuit 18 is used as the count input, so that when the two signal levels match during playback, the corresponding recording time is recorded.
This indicates the setting value of the EQ setting circuit 6. Therefore, if each of the circuits 6 to 8 is configured to have a storage device using a flip-flop or the like to store the output of the decoder 5, the EQ, bias, and level can be adjusted according to the output of the decoder 5 at that time. The value will be memorized and set.
In this way, the optimal recording EQ is adjusted and the reproduction in the reverse direction continues until the contents of the counter 4 become zero, and then the tape returns to the tape starting point and stops.

To adjust the recording bias, press switch S.
_2a to _S2c are switched to the bias side and the same procedure as above is performed, and when the levels of both reproduction signals ₁ and ₂ match, the recording bias setting circuit 8 is set in accordance with the output of the decoder 5.

The recording level is adjusted after the recording EQ and bias are adjusted to the optimum values through the above procedure. In this case, _the signal ₁
(450Hz) is recorded intermittently. When adjusting the recording level, the level of the reference voltage E by the switch _S2c is compared with the level of the playback signal ₁ , and the level setting circuit 6 sets the level according to the content of the decoder 5 when both levels match. That will happen.

Here, the rectifying and smoothing circuit ₁ corresponds to the output level of the rectifying and smoothing circuit 15 of the reproduced signal 1 and the reference voltage E.
In a tape recorder whose recording level is adjusted to match the output level of 6, if a signal at a specified input level (for example, 400Hz) is input, the tape will have a specified magnetic flux density. The reference voltage E is set so as to obtain such a relationship.

As described above, according to the present invention, recording characteristics can be automatically adjusted in a short time and efficiently, and the magnetic tape always returns to its initial state, which is advantageous.

It should be noted that the adjusting device shown in FIG. 3 is merely an example, and it is clear that various devices can be used.

[Brief explanation of the drawing]

1 and 2 are schematic plan views explaining each embodiment of the present invention, FIG. 3 is a block diagram of an adjusting device suitable for use in the present invention, and FIG. 4 is an operating waveform of the device shown in FIG. 3. It is a diagram. Explanation of symbols of main parts 10...Head, 11
...Tape, 19,20...Tape reel, 2
3, 24... Capstan, 25, 26... Pinch roller.

Claims (1)

[Claims] 1. While running the magnetic tape in one direction, one of the recording level, recording bias, and recording compensation amount is sequentially changed to record an adjustment signal on the magnetic tape for a predetermined period, and then the magnetic tape is A method for adjusting recording characteristics of a tape recorder, wherein the recording characteristics are adjusted by detecting the playback level of the adjustment signal while running the tape recorder in the opposite direction. 2. The method according to claim 1, characterized in that the tape recorder is a recorder having an auto-reverse function capable of running playback in forward and reverse directions.