JPS6010366B2 - Automatic frequency characteristic adjustment device for magnetic recording and playback devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic frequency characteristic adjustment device for a magnetic recording and reproducing device.

The magnetic tapes used in magnetic recording devices have different magnetic properties depending on the magnetic material used, and the optimum value of the bias current value (bias amount) during recording and the recording sensitivity vary accordingly. Since other characteristics differ, magnetic recording and playback devices are typically set to the optimum bias current value and appropriately switched equalizer characteristics depending on the type of magnetic tape used. It is well known that this is happening. In the past, operations such as setting the bias amount and switching the equalizer characteristics according to the type of magnetic tape described above were generally performed by switching a manual switch, but recently, the above-mentioned operations have been changed. Attempts have begun to be made to do this automatically instead of manually, and the applicant's company has developed means for automatically setting the appropriate bias amount and automatically switching the recording and playback equalizers according to the appropriate bias amount. Completed a magnetic recording and playback device equipped with
A patent application (Samurai Kaoka No. 53-35485) has already been filed.

By the way, even if a magnetic recording/playback device is able to perform recording/playback with a small distortion rate by setting an appropriate amount of bias according to the type of magnetic tape used, the Differences in recording sensitivity and frequency characteristics that exist will appear as they are in the playback signal level, so if a noise reduction method is applied to the recording and playback signal system of a magnetic recording and playback device, this option will be useful when using complementary characteristics. The compression-expansion characteristics that have been achieved deviate from the complementary characteristics due to differences in the recording sensitivity of the magnetic tapes used, making it impossible to perform faithful recording and reproduction. The present invention automatically adjusts the transfer characteristics of a recording signal circuit so that a constant playback signal level can be obtained regardless of variations in recording sensitivity or differences in frequency characteristics that exist for each magnetic tape used. The present invention provides an automatic frequency characteristic adjustment device for a magnetic recording and reproducing device according to the present invention, which solves the above-mentioned problems. The specific contents will be explained.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an automatic frequency characteristic adjustment device for a magnetic recording and reproducing device according to the present invention. In FIG. 1, a recording head Hr and a reproducing head Hp are individually An example is shown in which the present invention is applied to a magnetic recording and reproducing device having the above-mentioned configuration, but in implementing the present invention, one magnetic head is used as a recording head in the Kagamine mode, It goes without saying that the present invention can also be applied to a magnetic recording and reproducing device configured to be used as a so-called green reproducing head, which also serves as a reproducing head in the reproducing mode. A green re-switching switch is provided with fixed contacts connected to the connection line to which the head Hr is connected and to the connection line to which the playback head Hp is connected, respectively, and one green re-switching switch is provided to the movable contact of the recording/reproducing change-over switch. It has a configuration in which the head is connected.

In FIG. 1, the spots are bias signal sources, and the output signal d from this bias signal source BS in recording mode is:
The signal is applied to the recording head Hr via an audio signal blocking capacitor ST. The current value of the bias signal applied from the bias signal source spot to the recording head Hr is set to a value suitable for the magnetic tape used.
In order to automatically set the appropriate bias amount for each magnetic tape used, the bias signal source BS is controlled by a control device (control logic device) as proposed by Kaisei Tokuto No. 3-85. In a preferred embodiment, the bias signal source BS includes a bias signal generator and an attenuator whose attenuation is made variable by a control signal from the control device LA. It is composed of such things as IS is an input terminal for the line input signal f to be recorded, and the input terminal IS
The line input signal f supplied to the information changeover switch S
The frequency of the output reference signal e is applied to the other fixed contact 8 of the changeover switch SW by the control signal X from the control device LA. If the value is, for example, IKHz and 1
A reference signal e {a sine wave signal with constant amplitude, whose frequency value is changed by switching} is provided from a reference signal generator PSC which is switched such as a plate ratio.

FIG. 2 is a circuit diagram showing an example of the configuration of a reference signal generator configured to generate reference signals of two frequency values. In FIG. This is a switch that performs switching control using a control signal x, and OSC1 and OSCh are
An oscillator OSCI for a KHz reference signal and an oscillator OSCh for a single Hz reference signal, and in the illustrated example, these reference signal oscillators OSC1 and OSCh are constructed of so-called phase-shifted oscillators.

The two switches S, S2 described above are each equipped with two sets of contacts that perform operations opposite to each other, and one switch stops the oscillation operation of one oscillator in response to the control signal When the output side is disconnected, the other switch enables the other oscillator to oscillate and the reference signal e is sent from the output side of that oscillator, or the opposite operation to the above is performed. (For example, depending on the high level state and low level state of the control signal
, S2 may be linked to perform the above-mentioned switching of operations).

The changeover switch SW is switched by a control signal g given from a control device LA (control logic device, e.g., microprocessor, microcomputer), and a signal sent from the output side of the changeover switch SW. Depending on the above-mentioned switching, h is made to be the line input signal f or it is made to be the reference signal e from the reference oscillator OSC.

The output signal h from the changeover switch SW is sent to the recording amplifier A, (
When the noise reduction method is applied, the recording amplifier is provided with the necessary compression characteristics) to the variable attenuator VA, and the output signal from the variable attenuator VA is the Takagi signal component. A recording amplifier A2 equipped with a variable high-frequency compensation circuit VHC whose compensation amount is variably controlled by a control signal Z from a control device LA, and a bias signal blocking circuit BT (for example, composed of a parallel resonant circuit)
It is simultaneously supplied to the recording head Hr via the above-mentioned bias signal. The variable attenuator VA described above is configured to be able to apply different attenuations to the signals to be recorded that are supplied to it depending on the control signal W that is supplied to it from the control device LA. This is true, for example, even if resistors with different resistance values are connected to the signal transmission path in a bridging manner by a multi-bit control signal W given from the control device LA. An example configuration is schematically shown in FIG.

In FIG. 3, AM is an analog multiplexer, and this analog multiplexer AM has a control signal W to it.
The signal transmission path is bridged with resistors R, ~Rn, each having a different resistance value, and the attenuation amount varies depending on the resistor Ra connected in series with the signal transmission path. is applied to the signal. Needless to say, if the control signal W has N bits, the number of variable steps of the attenuation amount will be 2N. Further, the above-mentioned variable Takagi compensation circuit VHC, in which the amount of compensation for the Takagi signal component is variably controlled by the control signal Z from the control device LA, is configured such that the amount of compensation for the Takagi signal component is variably controlled by the control signal Z from the control device LA. The structure may be such that the peaking frequency is changed depending on Z, and an example structure is schematically shown in FIG.

In FIG. 4, AM is an analog multiplexer, and in this analog multiplexer AM, a series connection circuit of a different resistor and a capacitor is connected to a coil L according to the numerical value of a digital signal added to it as a control signal Z. so that Therefore, the recording amplifier A2 equipped with the variable Takagi compensation circuit VHC adjusts the amount of the Takagi signal component of the recording signal passing through the recording signal transmission system to the control device LA.
It is changed in accordance with the control signal Z sent from the control signal Z to the variable Takagi compensation circuit VHC.

Now, in the frequency characteristic automatic adjustment device of the magnetic recording and reproducing device of the present invention, first, under the control of the control device LA, the first reference signal (a frequency selected from among the low frequency bands) from the reference signal generator OSC is A state in which a sine wave signal having a constant amplitude and a constant amplitude (for example, an IKHz sine wave signal) is recorded on a magnetic tape, and when it is reproduced, a reproduced signal with a signal level approximately equal to a predetermined signal level is obtained. The amount of attenuation of the variable attenuator VA provided in the recording signal transmission system is automatically set so that the above-mentioned variable attenuator V
With the attenuation amount of
Hz sine wave signal) is recorded on a magnetic tape, so that when it is reproduced, a reproduced signal with a signal level approximately equal to the predetermined signal level described above is obtained.
A variable Takagi compensation circuit installed in the recording signal transmission system automatically sets the amount of compensation for the Takagi signal component to ensure that it always has a substantially flat frequency, no matter what type of magnetic tape is used. The magnetic recording/playback device is operated as having a response characteristic, but it is important to know how to set the amount of attenuation in the variable attenuator VA and to compensate for the high frequency signal component in the variable high frequency compensation circuit. There are two typical ways to set the amount, but here we will give an overview of the two ways to set the attenuation amount of the variable attenuator VA as an example. Then, the result is as follows.

One method is to detect and measure the signal levels of successive reference signals obtained by changing the amount of attenuation with respect to the reference signal e in stages and the corresponding reproduced signal, and then compare and calculate the levels with a predetermined reference value. The state of the variable attenuator VA in the recording signal transmission system (recording signal circuit) is automatically set so that the amount of attenuation that minimizes the difference from the recording signal is given to the recording signal, and , the other one is to record the reference signal e on a magnetic tape with an appropriately determined amount of attenuation given to it, and to detect and measure the level of the reproduced signal when the magnetic tape is reproduced. By comparison calculation with a predetermined reference value, the state of the variable attenuator VA in the recording signal circuit is automatically set so that the recording signal is given an attenuation amount that minimizes the difference from the reference value. (The two methods for setting the amount of compensation for the variable high-frequency signal component are the same as in the case of the variable attenuator described above.)

Now, the first reference signal, which has been given a predetermined amount of attenuation by the variable attenuator VA provided in the recording signal circuit, is recorded on the magnetic tape as a recording signal, or the first reference signal is provided in the recording signal circuit. A reproduction signal i obtained by reproducing a magnetic tape on which a second reference signal, to which a predetermined compensation has been applied by a variable Takashiro compensation circuit VHC, is recorded as a recording signal, is applied from a reproduction head HP to a reproduction amplifier A3. Then, the signal K amplified by the regenerative amplifier A3 is sent to the output terminal via the regenerative amplifier (if a noise reduction method is applied, the regenerative amplifier A4 is given the required expansion characteristic). At the same time, the output signal K from the regenerative amplifier A3 is applied to a signal level detection circuit Det (envelope detector 戊t) to detect the signal level of the reproduced signal.

Output signal 1 from the signal level detection circuit Det described above
is an integrating circuit I for removing level fluctuations of the reproduced signal.
Integration is performed at A, and the reset and start of the integration operation of this integration circuit IA is controlled by a signal m from the control device LA. The output signal n from the integrating circuit IA is
It is compared with a predetermined constant voltage value n' in the comparator circuit CM, and the comparator circuit CM provides an integration end output signal t to the control device LA.

The control device LA receives the integration end output signal t and performs a predetermined operation as described below to obtain a predetermined integral value of the signal level of the reproduced signal when the reference signal e is recorded and reproduced. For the first reference signal, the attenuation amount of the variable attenuator VA in the recording signal circuit is automatically set, and the second reference signal is automatically set.
Regarding the reference signal, the amount of compensation of the variable Takagi compensation circuit VHC in the recording signal circuit is automatically set, and the frequency characteristics are automatically adjusted so as to be in a substantially flat state.

The frequency characteristic automatic adjustment device of the magnetic recording and reproducing device performs control operations according to a series of programs by applying the signal yr to the control device LA by operating the frequency characteristic automatic adjustment wholesale SBf on the operation panel ○D. will be started.

The operation panel ○D mentioned above is equipped with various button switches such as recording, playback, fast forward, rewind, and stop, as well as a button to start the automatic bias setting operation, similar to the operation panel of a normal magnetic recording and playback device. You can leave it there. Next, the details of the operation of the automatic frequency characteristic adjustment device for the magnetic recording/reproducing device of the present invention will be explained with reference to the flowcharts shown in FIGS. 5 and 6.

First, the flowchart shown in FIG. 5 detects the signal levels of successive reference signals and corresponding reproduction signals obtained by changing the attenuation amount with respect to the first reference signal in steps under the control of the control device LA. Automatically set the state of the variable attenuator VA in the recording signal circuit so that the recording signal is given an attenuation amount that minimizes the difference from the reference value by measuring and comparing with a predetermined reference value, The variable attenuator VA in the recording signal circuit is kept in the state set by the setting operation described above, and then the variable Takagi compensation circuit V is set by the second reference signal.
This is a case where the compensation amount of the Takagi signal component by HC is automatically set as required. In Figure 5, step 1
When the frequency characteristic automatic adjustment plow SBf on the operation panel CD is pressed and the signal yf is given to the control device LA,
The program exits the idle loop and proceeds to step 2. In step 2, the selector switch SW is controlled by the signal g from the control device LA so that the reference signal e from the reference signal generator OSC is outputted from the switch SW as the output signal h. In step 3, the first reference signal (IK signal) is sent from the reference signal generator PSC in response to the signal X from the control device LA, and this is applied to the recording amplifier A via the changeover switch SW. . In step 4, the variable high frequency compensation circuit VHC is adjusted by the signal Z from the control device LA so as to provide a medium level compensation to the recording signal.

In step 5, the attenuation amount of the variable attenuator VA is set using the signal W from the control device LA so that the attenuation amount of the variable attenuator VA reaches its maximum value, and in step 6, a delay of a certain time is applied (recording In step 7, the control signal m from the control device LA starts the integration operation of the integrating circuit IA, and The signal level of the signal K obtained by amplifying the output signal i by the regenerative amplifier A3 is detected by the signal level detection circuit Det, and the signal 1 obtained is integrated by the integrating circuit IA.
A built-in timer counter of the control device LA is started at the same time as the integration operation starts at A, and in step 9, when the output signal n from the integration circuit IA exceeds a constant voltage value n' set in the comparison circuit CM, the comparison circuit is activated. The timer counter in the control device LA is stopped by the signal t output from the CM, and in step 10, when the value of the timer counter becomes equal to or smaller than a preset reference value (that is, the average value of signal 1 is If the value of the timer counter is equal to or larger than the preset reference value, the process goes to step 12.Contrary to the above, if the timer counter value is larger than the preset reference value, the process goes to step 12. 1
Go to 1. In step 11, if the number of times the attenuation amount of the variable attenuator VA is controlled has not reached the value of the number of variable stages of the variable attenuator VA, a control signal W is output that reduces the attenuation amount by one step, and the process proceeds to step 6. Go back and if it has been reached, proceed to step 12. In step 12, the second reference signal (1-Hz signal) is sent out from the reference signal generator OSC in response to the signal x from the control device LA, and this is applied to the recording amplifier A via the changeover switch SW. do.

In step 13, the amount of compensation of the Takagi signal component by the variable Takagi compensation circuit VHC is minimized by the signal Z from the control device LA, and from step 14 to step 1
In step 7, the same operations as those performed in steps 6 to 9 described above are performed, and step 18
Then, when the value of the timer counter becomes equal to or smaller than the preset reference value (that is, when the average value of signal 1 becomes equal to or larger than the value corresponding to the preset reference value), the process ends. However, in contrast to the above, if the value of the timer counter is larger than the preset reference value, the process proceeds to step 19.

In step 19, control of the compensation amount of the Takagi signal component by the variable Takagi compensation circuit VHC is performed by the variable Takagi compensation circuit VHC.
If the value of the variable stage number in C has not been reached, a control signal Z is outputted to increase the compensation amount of the high frequency signal component by one step, and the process returns to step 14; if the value has been reached, the process ends.

In the finished state, the signal level of the reproduced signal from the magnetic tape is not flat from low to high due to the level setting for the recording signal by the variable attenuator VA and the variable high frequency compensation circuit VHC provided in the recording signal circuit. It is used to indicate the response characteristics.

Next, the flowchart shown in FIG. 6 shows that the first and second reference signals are each recorded on a magnetic tape at a suitably determined specific signal level, and when the magnetic tape is played back. The attenuation amount in the variable attenuator VA and the Takagi signal component by the variable Takagi compensation circuit VHC are determined so that the difference between the detected measured value of the reproduced signal level and a predetermined reference value is minimized by a comparison calculation with the reference value. This is a case where the frequency characteristics are automatically adjusted so that the compensation amount is given to the recording signal.

In the flowchart shown in the sixth figure, steps from "r start" to step 9A are the same as those from "beginning" to step 9 in the flowchart shown in the fifth figure described above.

In FIG. 6, in step 10A following step 9A, the attenuation amount of the variable attenuator VA is made appropriate by the signal W according to the difference from a preset reference value, and then in step 11A, the control device A second reference signal (10 KHz signal) is sent from the reference signal generator PSC in response to the signal x from LA, and this is given to the recording amplifier A via the changeover switch SW.
In step 13A, the amount of compensation of the Takagi signal component by the variable Takagi compensation circuit VHC is set to a maximum of 4 by the signal Z from the control device LA, and in step 13A, the green retime between the recording head Hr and the playback head Hp is adjusted. A delay of a time corresponding to the deviation is given, and in step 14A, the integrating operation of the integrating circuit mountain is started by the control signal m from the control device LA,
The signal level of signal x obtained by amplifying the output signal i of the reproducing head Hp by the reproducing amplifier A3 is detected by the signal level detection circuit Det, and the obtained signal 1 is integrated by the integrating circuit IA.In step 15A, the integrating circuit IA integrates the signal 1. At the start of the operation, a timer counter built in the control device LA is started, and in step 16A, when the output signal n from the integrating circuit IA exceeds a constant voltage value n' set in the comparator circuit CM, the output signal is output from the comparator circuit CM. The timer counter in the control device LA is stopped by the signal t, and the process proceeds to step 17.
At A, the amount of compensation for the Takagi signal component in the variable Takagi compensation circuit VHC is made appropriate by the signal Z according to the difference from a preset reference value, and the process ends.
In the finished state, the signal level of the reproduced signal from the magnetic tape is not flat from the low range to Fujishiro due to the level setting for the recording signal by the variable attenuator VA and the variable Takagi compensation circuit VHC provided in the recording signal circuit. It is considered to be indicative of spon characteristics.

As is clear from the above detailed explanation, in the frequency characteristic automatic adjustment device of the magnetic recording and reproducing device of the present invention, the frequency characteristic automatic adjustment nail SB on the operation panel ○D
By simply pressing f, the reference level of the reproduction signal reproduced from the energy tape is made constant regardless of the magnetic tape, and it is made to exhibit flat response characteristics from the low frequency range to the high frequency range. Even if various magnetic tapes are used in a magnetic recording/playback device to which a noise reduction method is applied, there is no change in the quality of the reproduced sound, and therefore, according to the present invention, high fidelity A magnetic recording and reproducing device capable of recording and reproducing can be easily provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the automatic frequency characteristic adjustment bag counterfeit of the magnetic recording and reproducing device of the present invention, and FIG.
3 is a block diagram showing an example configuration of a variable attenuator, FIG. 4 is a block diagram showing an example configuration of a variable Takagi compensation circuit, and FIGS. FIG. 6 is a flowchart for explaining the operation. LA...control device, IS...line input signal input terminal, SW...changeover switch, OSC...
Reference signal generator, VA...variable attenuator, BS...
...Bias signal source, 00...Operation panel, VHC...
Variable Takagi compensation circuit ~ Hr...Recording head, Hp
...Reproduction head, A, ~A4...Amplifier, Det...Level detection circuit, IA...Integrator circuit, CM...Comparison circuit. Atsushi's illustrations 2, 3, 3, 5, 5, 6

Claims (1)

[Claims] 1. A reference signal generator that individually generates a plurality of reference signals having different frequency values according to a switching control signal given from the control device, and a line input signal generator that individually generates a plurality of reference signals having different frequency values according to a switching control signal given from the control device. A changeover switch that switches between the signal and the reference signal from the reference signal generator, and is provided in the recording signal transmission system after the output side of the changeover switch, and attenuates the recording signal in accordance with the control signal from the control device. A variable attenuator that makes the amount of compensation variable, a variable high-frequency compensation circuit that makes the amount of compensation for high-frequency components variable according to a switching control signal given from a control device, and an integrating circuit that uses a control signal from the control device. means for variably controlling the variable attenuator and the variable high-frequency compensation circuit so that the amount of attenuation in the variable attenuator and the amount of compensation for the high-frequency component by the variable high-frequency compensation circuit are constant throughout the integration operation;
a level detection circuit that detects the signal level of a reproduced signal from a magnetic tape; an integration circuit that integrates the output signal from the level detection circuit; and a comparison between the output signal of the integration circuit and a predetermined reference value. a comparison circuit that generates an integration end output signal and supplies the integration end output signal to a control device; and a comparator circuit that sequentially records a plurality of reference signals on a magnetic tape and generates the integration end output signal when it is played back. A magnetic recording and reproducing device comprising means for automatically adjusting a variable attenuator and a variable high-frequency compensation circuit so that the integration time obtained by the above substantially coincides with the time value of a reference signal to be compared. Frequency characteristic automatic adjustment device.