JPH04176002A - Recording bias automatic adjusting circuit for tape recorder - Google Patents

Abstract

PURPOSE:To achieve a bias adjusting operation without the worsening of operability by moving a magnetic tape with a quick feed operation to perform a bias adjusting operation again when adjusting operation of a bias current does not end within a specified time. CONSTITUTION:Two reference signals with different frequencies are recorded on a magnetic tape with a recording head 7 while a reference signal recorded on the magnetic tape is reproduced with a reproduction head 9 and a recording bias current is adjusted automatically based on a level difference between reference signals reproduced. When a bias adjusting operation does not end within a specified time, a quick feeding operation of the magnetic tape is performed for a specified time while the bias adjusting operation is performed again. This enables the performing of a bias adjusting operation without aggravating operability.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a tape recorder, and more particularly to an automatic recording bias adjustment circuit.

(b) Conventional technology Tape recorders that record signals such as music onto magnetic tape are in widespread use, but such tape recorders are configured to record signals onto magnetic tape by supplying a bias of 11tKE to the recording head. has been done. There are three types of such magnetic tapes: normal tape, chrome tape, and metal tape, and the bias can be changed depending on the characteristics of each tape. Further, even for magnetic tapes of the same type, the characteristics differ between magnetic tapes made by different companies, so the optimum bias current value will be different. In popular tape recorders, this bias current value is set according to the type of magnetic tape, but in high-end tape recorders, the bias current value can be variably adjusted to suit the characteristics of each magnetic tape. It has functions. There are two ways to adjust the bias flow: manual and automatic, but automatic bias is easier to operate. As a technique for automatically adjusting the thick awning of such bias current, for example, Japanese Patent Application Laid-Open No. 61-3
There is one disclosed in Publication No. 9203.

(c) Problems to be Solved by the Invention The automatic adjustment operation of the bias current is performed by the technology disclosed in the above-mentioned publication, but the position where the bias adjustment operation is started is caused by damage to the leader tape or damage. If it is a part of the magnetic tape, no adjustment operation will be performed.

The conventional technology is configured to stop the adjustment operation if it is not completed within a predetermined time, which requires the user to perform the bias adjustment operation again, which is extremely troublesome. It was inconvenient. The present invention aims to provide an automatic recording bias adjustment circuit that is improved in this respect.

(d) Means for Solving the Problems The automatic recording bias adjustment circuit of the present invention is configured such that when the bias adjustment operation is not completed within a predetermined time, the bias adjustment operation is performed again after fast-forwarding the magnetic tape. This is what I did.

(E) Effect In the present invention, if the bias flow adjustment operation is not completed within a predetermined time, the magnetic tape is moved by a fast forward operation and the bias adjustment operation is performed again, so that the operability is not deteriorated. The bias adjustment operation can be performed without any bias.

(f) Embodiment The illustrated circuit is an embodiment of the recording bias automatic adjustment circuit of the present invention. In the figure, (1> is an input terminal into which a recording signal is input, (2) is a preamplifier circuit that amplifies the recording signal input from the input terminal (1), and its output terminal is a switch switch. It is connected to the first terminal (3a) of Z Te (3). (4) is H (high) to the control terminal (4a).
This is a reference signal generating circuit which becomes active when a level signal is applied and generates first and second reference signals of different frequencies, for example, 400 Hz and 10 KHz, and its gravity terminal is connected to the selector switch (3). Second terminal (3b)
It is connected to the. (5) is the changeover switch (3) when the H level signal is not applied to the control terminal (5a).
A switch circuit (6
) is a recording amplification circuit whose input terminal is connected to the movable terminal (3c) of the changeover switch (3), and (7) is a recording amplification circuit to which the signal amplified by the recording amplification circuit (6) is applied. A recording head that records signals onto magnetic tape (
8) is a bias oscillation circuit that supplies a bias current to the recording head (7), (9) is a playback head that plays back the signal recorded on the magnetic tape, and (10) is a signal that is played back by the playback head (9). This is a reproducing amplifier circuit which receives a signal inputted by the user and amplifies the signal, and its output signal is connected so that it can be input to a monitor amplifier circuit (not shown). (11) is the level between the first and second reference signals which are in operation when the H level signal is fully applied to the control terminal (lla) and are amplified and input by the reproducing amplifier circuit (10). The level difference detection circuit (12) for detecting the difference is a bias adjustment circuit that becomes active when the H level signal is applied to the control terminal (12a), and the level difference detection circuit (12) is a bias adjustment circuit that is activated when the H level signal is applied to the control terminal (12a). The bias oscillation circuit (8)
It has the effect of varying the magnitude of the bias current output. And the adjustment operation of the bias current is as follows.
It is configured to change the value of the bias in a direction in which the level difference between the first and second reference signals that can be completely reproduced by the reproducing head (9) becomes smaller. (13) is an operation control circuit that switches the tape recorder to each operating state according to the switching operation of the recording operation switch (14), etc., which is pressed and closed during recording operation, and (15) is an operation control circuit that is used when adjusting the recording bias. Bias adjustment operation switch that is pressed and closed (
16) is a recording drive signal output terminal that outputs an H level drive signal when the recording operation switch (14) or bias adjustment operation switch (15) is closed;
) is a recording switching circuit which becomes active when the H level drive signal is fully output to the recording drive signal output terminal (16), and has the function of putting the tape recorder into the recording operation state. (18) When the bias adjustment operation switch (15) is pressed and closed, an H level control signal is output and the level difference detection circuit (11)
This is a control signal output terminal that outputs an L (low) level signal when there is no difference in level between the first reference signal and the second reference signal detected by the reference signal generating circuit (4).
), the control terminal (5a) of the switch circuit (5), the control terminal (ll) of the level difference detection circuit (11)
a) and the control terminal (12a) of the bias adjustment circuit (12)
) is not connected. (19) is a fast-forward drive signal output terminal that outputs an H-level drive signal when the fast-forward operation switch (not shown) is closed or when the bias adjustment operation is not completed within a predetermined time; (2o) is a fast-forward switching circuit which becomes active when an H-level drive signal is output to the fast-forward drive signal output terminal (19), and has the function of putting the tape recorder into a fast-forward operating state. (21) is a timer circuit that starts a timer operation when the bias adjustment operation is started by closing the bias adjustment operation switch (15), and outputs a switching signal to the output terminal (22) after a predetermined time elapses. It has been configured to do so. In such a circuit configuration, when the bias adjustment operation switch (15) is fully pressed and closed, the recording drive signal output terminal (16) and the control signal output terminal (
When the H level signal is output to the timer drive signal output terminal (23>), the timer circuit (21) is activated. When the level difference between the first reference signal and the second reference signal detected by the detection circuit (11) disappears, the output signals of the recording drive signal output terminal (16) and the control signal output terminal (18) become H level. The output signal of the timer drive signal output terminal (23) is inverted from the H level to the L level. If the bias current adjustment operation is not completed within a predetermined time, that is, the time set by the timer circuit (21), a switching signal is output from the output terminal (22) of the timer circuit (21>).
By inputting the switching signal to the operation control circuit (13), the output signals of the recording drive signal output terminal (16) and the control signal output terminal (18) are inverted from H level to L level, and the fast forward drive signal is output. The configuration is such that a bell signal is output to the terminal (19) for a predetermined period of time, for example, 10 seconds.Furthermore, when the fast-forward operation is completed, the recording drive signal output terminal (16) and the control signal output terminal (18) are output. )
The automatic bias adjustment circuit of the present invention is configured such that an H level signal is output to the timer drive signal output terminal (23) and the bias adjustment operation is performed again. Next, the operation will be explained.

When the recording operation switch (14) is pressed to close, an H level drive signal is output to the recording drive signal output terminal (16). When an H level drive signal is output to the recording drive signal output terminal (16), the recording switching circuit (17)
enters the operating state, causing the tape recorder to enter the recording operating state. The recording signal applied to the input terminal (1) is input to the preamplifier circuit (2), amplified, and then input to the recording amplifier circuit (6) through the changeover switch (3).

The recording signal input to the recording amplifier circuit (6) is amplified and then applied to the recording head (7) together with the bias current from the bias oscillation circuit (8).
7) allows recording onto magnetic tape. The signals thus recorded on the magnetic tape are reproduced by a reproduction head (9) and then input to a reproduction amplifier circuit (10). The reproduction signal input to the reproduction amplifier circuit (10) is amplified and then input to the monitor amplifier circuit where it can be fully amplified, so that the signal recorded on the magnetic tape can be monitored by the recording head (7). . The recording operation is performed in this way, but if the stop operation is performed in such a state, the output signal of the recording drive signal output terminal (16) goes high.
The recording switching circuit (17) inverts the level to the L level.
Since the tape recorder becomes inoperative, the tape recorder is returned to a stopped state.Recording operations are performed as shown in FIG.

When the bias adjustment operation switch (15) is pressed and closed, an H level signal is output to the recording drive signal output terminal (16) and the control signal output terminal (18) provided in the operation control circuit (13). At the same time, an H level signal is output to the timer drive signal output terminal (23). When an H level drive signal is not output to the recording drive signal output terminal (16), the recording switching circuit (17) is activated and the tape recorder is put into the recording operation state. Further, when an H level signal is output to the timer drive signal output terminal (23), the timer circuit (21) becomes operational and starts timer operation. The H level control signal output to the control signal output terminal (18) is
Control terminal (4a) of the reference signal generation circuit (4), control terminal (5a) of the switch circuit (5), level difference detection circuit (1)
1) control terminal (lla) and bias adjustment circuit (12)
) can be applied to the control terminal (12a). When the H level signal is fully applied to the control terminal (4a) of the reference signal generation circuit (4), the reference signal generation circuit (4) becomes operational and generates the first and second reference signals of 400Hz and 10KHz. Output.

Further, when the H level signal is applied to the control terminal (58) of the switch circuit (5), the changeover switch (3) is switched to the opposite side from the state shown in the figure, so that the reference signal generation circuit (4) outputs the signal. The first and second reference signals are now ready to be input to the recording amplifier circuit (6). The first and second reference signals input to the recording amplifier circuit (6) are
After being amplified, the bias from the bias oscillation circuit (8) is applied to the recording head (7) along with the current, and the recording head (7) records on the magnetic tape. The first and second reference signals recorded on the magnetic tape are transmitted to the playback head (9).
) and then input to the reproduction amplifier circuit (10) where it is amplified. The first and second reference signals amplified by the reproduction amplifier circuit (10) are input to the level difference detection circuit (11) which is in operation, and the level difference thereof is detected. When a detection signal corresponding to the level difference detected by the level difference detection circuit (11) is input to the bias adjustment circuit (12), the bias adjustment circuit (12)
A signal for varying the bias current can be outputted to the bias oscillation circuit (8) so that the level difference between the signals is eliminated. When the bias adjustment circuit (12) adjusts the bias current from the bias oscillation circuit (8), the level of the signal that can be completely recorded on the magnetic tape changes, and the level of the signal that can be completely recorded on the magnetic tape changes, and the first reference signal and the first reference signal that can be completely reproduced by the playback head (9) change. The level between the two reference signals gradually decreases, and as the variable operation progresses further, the level difference between the signals disappears. When the level difference between the reference signals disappears, the recording drive signal output terminal (16), control signal output terminal (18), and timer of the operation control circuit (13) are output based on the signal output from the level difference detection circuit (11). The output signal of the drive signal output terminal (23) is inverted from H level to L level. When the output signal of the recording drive signal output terminal (16) is inverted from the H level to the L level, the recording switching circuit (17) becomes inactive, and the tape recorder is switched to a stopped state. Further, when the output signal of the control signal output terminal (18) becomes L level, the reference signal generation circuit (4), level difference detection circuit (11) and bias adjustment circuit (12) become inoperable, and the changeover switch (3) becomes inoperable. ) is switched to the state shown. Then, the timer circuit (21) becomes inactive because the output of the timer drive signal output terminal (23) becomes L level, and no switching signal is output to the output terminal (22). The recording bias adjustment operation ends, but the bias current value supplied from the bias oscillation circuit (8) to the recording head (9) is set according to the characteristics of the magnetic tape. If the recording operation is performed after rewinding the magnetic tape to the bias adjustment start position, the signal input from the input terminal (1) can be recorded on the magnetic tape with the best characteristics.

The normal bias adjustment operation is performed as described above, but next we will explain the operation when the position where the bias adjustment operation is started is the leader tape portion or a damaged magnetic tape portion. If the aforementioned bias adjustment operation is started from such a position, the bias current cannot be adjusted so that the levels of the first reference signal and the second reference signal, which can be completely recorded on the magnetic tape within a predetermined period of time, are the same. When a predetermined period of time has elapsed while such a bias adjustment operation is being performed, a switching signal is output to the output terminal (22) of the timer circuit (21). When the switching signal from the timer circuit (21) is input to the operation control circuit (13), the output signals of the recording drive signal output terminal (16), the control signal output terminal (18), and the timer drive signal output terminal (23) are output. is inverted from the H level to the L level, and an H level drive signal is output to the fast forward drive signal output terminal (19) for 10 seconds. When such an operation is performed, the recording operation is canceled and the reference signal generation circuit <4), level difference detection circuit (11), bias adjustment circuit (12) and timer circuit (21) become inactive. On the other hand, when an H-level signal is output to the fast-forward drive signal output terminal (19), the fast-forward switching circuit (20) is activated, causing the tape recorder to enter the fast-forward operating state. When 10 seconds have elapsed in the fast-forward operation state, the fast-forward drive signal output terminal (19)
The output signal of is inverted from H level to L level. As a result, the fast-forward switching circuit (20) becomes inactive, and the tape recorder is switched to a stopped state. When such an operation is performed, the recording drive signal output terminal (16
), the H level signal is output to the control signal output terminal (18) and the timer drive signal output terminal (23), and the bias adjustment operation described above is performed again. Such a bias adjustment operation is performed at a position 10
Since it can be started from the position fast-forwarded by seconds, the bias adjustment operation can be performed not on the leader tape part.

If the second bias adjustment operation is not performed, it is determined that the bias adjustment is not possible and the bias adjustment operation state is canceled.

When the aforementioned recording bias adjustment operation is completed, if the magnetic tape is rewound to the adjustment start position and then the recording operation is performed, a bias current that matches the characteristics of the magnetic tape can be supplied to the recording head (7). , it is possible to obtain excellent recording characteristics.

In this embodiment, if the recording bias adjustment operation is not performed for the second time, the bias adjustment operation is canceled, but it is also possible to perform the adjustment operation for the third time. In addition, the operation control circuit (1
3), level difference detection circuit (11), bias adjustment circuit (
12), the timer circuit (21), etc. can be constructed by a microcomputer.

(G) Effects of the Invention The automatic recording bias adjustment circuit of the present invention is configured to move the magnetic tape by fast-forwarding and perform the bias adjustment again if the bias current adjustment operation is not completed within a predetermined time. Therefore, it has the advantage that the bias adjustment operation can be performed without deteriorating the operability.

BRIEF DESCRIPTION OF THE DRAWINGS The illustrated circuit is an embodiment of the recording bias automatic adjustment circuit of the present invention. Explanation of main drawing numbers (3)...Choice switch, (4)...Reference signal generation circuit, (5)...Switch circuit, (6)...
・Recording amplifier circuit, (7)... Recording head, (8
)...Bias oscillation circuit, (9)...Reproduction head, (10)...Reproduction amplifier circuit, (11)...
・Level difference detection circuit, (12)...Bias adjustment circuit, (13)...Operation control circuit, (17)...
Recording switching circuit, (20)... Fast forwarding switching circuit,
(21)...Timer circuit.

Claims (1)

[Claims] (1) Two reference signals with different frequencies are recorded onto a magnetic tape by a recording head, and the reference signal recorded on the magnetic tape is played back by a playback head, and a recording bias is applied based on the level difference between the played back reference signals. A tape recorder configured to automatically adjust the current is characterized in that when the bias adjustment operation is not completed within a predetermined time, the magnetic tape is fast-forwarded for a predetermined time and the bias adjustment operation is performed again. Automatic recording bias adjustment circuit for tape recorders.