JPH0954906A - Rotary head magnetic recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary head magnetic recording/reproducing device capable of simultaneously optimally controlling both of a frequency characteristic and a recording current of a head by a common recording equalization circuit according to a wear state of a recording magnetic head and measuring the gap depth of the head only by detecting a signal without affecting the resonance frequency of the head. SOLUTION: The recording equalization circuit 11 is constituted so as to output a recording signal adding the recording signal to the recording signal passing through a high-pass filter 102 and a gain control circuit 103 by an addition circuit 101 and equalized. A gap depth measuring circuit controlling the recording equalization circuit 11 detects a signal occurring in an auxiliary winding 15b with the less number of turns of winding wound around the recording magnetic head 15 in addition to a main winding 15a by a detection circuit 16, and calculates and stores a gap depth by a gap depth operation circuit 108, and controls the gain of the gain variable circuit 103 by a control circuit 19 according to the gap depth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type magnetic recording / reproducing apparatus such as a digital video tape recorder, and more particularly to recording equalization added to the recording side for compensating the frequency characteristic of a recording magnetic head. The present invention relates to a gap depth measuring circuit for a magnetic head, which controls the recording equalization circuit by measuring the gap depth from the worn state of the circuit and the magnetic head.

[0002]

2. Description of the Related Art A rotary head type magnetic recording / reproducing apparatus, for example, a broadcasting / commercial digital video tape recorder for recording / reproducing a digitized television signal,
Rotate the rotating cylinder wrapped with magnetic tape at high speed,
A high bit rate digital signal is supplied to the magnetic head mounted on the rotating cylinder to perform high density recording. For example, a D3 format digital video tape recorder supplies a signal of 112 Mbps, and a 1-inch high-definition digital video tape recorder supplies a signal of 148.5 Mbps to a magnetic head for recording on a magnetic tape.

When such a high bit rate digital signal is supplied to the magnetic head for high density magnetic recording, the reproduced waveform from the magnetic tape depends on the recording signal due to the frequency characteristics of the magnetic head. Subject to nonlinear distortion. Y.
Hashimoto, H.Nakaya and T.Yoshinaka's paper “AN EXP
ERIMENTAL HDTV DIGITAL VTR WITH A BIT RATE OF 1.18
8 Gbps ”, IEEE TRANSACTION ON BROADCASTING, VOL.BC-3
3, NO.4, DECEMBER 1987, page 204. No. 2 discloses a photograph of a reproduced waveform that has undergone nonlinear distortion. Also, on page 205 of the same paper, it is disclosed that in order to reduce this non-linear distortion, recording equalization that suppresses signals in the low frequency band and delays signals in the high frequency band is performed. FIG. No. 2 discloses a photograph of the reproduced waveform after recording equalization.

Furthermore, Yoshinobu Oba and Hiromichi Shibatani et al., "Development Research of 1/2 inch Digital VTR (D-3) for Broadcasting", NHK Giken R & D, No-17, December 1991, page 45, and JP-A-53-14901
No. 2, JP-A-63-7501 and the like disclose recording equalization characteristics for compensating the frequency characteristics of the magnetic head.

On the other hand, when the rotating cylinder is rotated at a high speed for recording / reproducing, the relative speed between the rotating magnetic head mounted on the rotating cylinder and the magnetic tape becomes large, so that the wear of the magnetic head becomes remarkable, There is a problem that the gap depth of the magnetic head becomes smaller with time. As a result, the recording current flowing through the magnetic head deviates from the optimum recording current, and the frequency characteristic of the magnetic head also changes, making it impossible to perform good recording. In order to prevent deterioration of the recording state due to wear of the magnetic head,
Adjust the recording current according to the gap depth of the magnetic head,
It is necessary to always make the optimum recording current flow to the recording magnetic head, and also to adjust the frequency characteristic of the recording equalization circuit.

Japanese Unexamined Patent Publication No. 2-281401 and Japanese Unexamined Patent Publication No. 4-341901 disclose methods for measuring the amount of wear of the magnetic head or the gap depth of the magnetic head.
A method for adjusting the recording signal level by calculating the optimum recording current value using the measurement result is disclosed, and also Japanese Patent Laid-Open No. 3-1.
Japanese Patent No. 22810 discloses a method of detecting a worn state of a magnetic head and controlling a recording current value and a frequency characteristic of the recording current based on the detected state.

FIG. 3 shows a recording side circuit of a wear detecting device for a magnetic head and a rotary head type magnetic recording / reproducing device disclosed in an embodiment of Japanese Patent Laid-Open No. 3-122810. FIG. 3 is a simplified block diagram of a part of a recording side circuit when applied to a rotary head type magnetic recording / reproducing apparatus equipped with a recording driver of a magnetic head. In addition, recording a high bit rate digital signal
In a rotary head type magnetic recording / reproducing apparatus for reproducing, a recording driver for a magnetic head is generally mounted on a rotating cylinder, and such a configuration is also shown in FIG.

In FIG. 3, a digital signal which is modulated as a recording signal by adding an error correction code to the digital data to be recorded and formatting is input to the input terminal 31. The input digital signal is subjected to recording equalization in the recording equalization circuit 32 for compensating the frequency characteristic of the recording magnetic head 37, and the recording current flowing in the recording magnetic head 37 in the recording level adjusting circuit 33. Is adjusted to a optimum recording current, and then input to the rotary transformer 35 via the rotary transformer drive circuit 34. The rotary transformer 35 is
This rotary transformer 3 is an element that performs non-contact signal transmission between a fixed side circuit and a rotating side circuit of a rotary cylinder.
The signal transmitted to the rotating side by 5 is input to the recording driver 36 mounted on the rotating cylinder. The recording driver 36 drives the recording magnetic head 37 to supply a required recording current.

The recording magnetic head 37 which is a signal indicating the gap depth (or wear amount) of the recording magnetic head 37.
And the output current value of the recording driver 36 are detected by the gap depth detection circuits 38 and 39, respectively.
It is input to the fixed-side gap depth calculation circuit 42 via the rotary transformers 40 and 41, respectively. The gap depth calculation circuit 42 calculates the gap depth from the two signals sent from the gap depth detection circuits 38 and 39 via the rotary transformers 40 and 41, and records based on the gap depth. A signal for adjusting the equalization characteristic (frequency characteristic) of the equalizing circuit 32 and the output level of the recording level adjusting circuit 33 is created, and the recording equalizing circuit is provided via the frequency characteristic control circuit 43 and the recording level control circuit 44, respectively. Three
2 and the recording level adjusting circuit 33 are controlled.

As the recording equalizing circuit 32, for example, a circuit using a first-order advance element or a transversal filter circuit having a simple structure is used, and the recording level adjusting circuit 33 is as follows.
A variable gain amplifier or a multiplier that can control the gain is used. As the gap depth calculation circuit 42, there is used a circuit configuration in which an input signal is analog-digital converted, a gap depth is calculated by a computer, this information is stored in a memory, and a signal is output by digital-analog conversion. .

In a rotary head type magnetic recording / reproducing apparatus having a magnetic head wear state detecting device having such a structure in a recording side circuit, when the recording magnetic head 37 is worn and the recording state is deteriorated, the wear state is deteriorated. A recording signal (for example, a sine wave signal) for detecting the
To the gap depth measurement mode. At this time, the rotary head type magnetic recording / reproducing apparatus is set in a state in which recording on the magnetic tape is not performed.

Then, the terminal voltage waveform of the recording magnetic head 37 and the current waveform of the recording driver 36 when a sine wave signal, which is a recording signal for detecting the wear state, is applied are gap depth detection circuits 38, 39. Respectively detected by
The gap depth of the worn recording magnetic head 37 is calculated by inputting it to the gap depth calculation circuit 42 via the rotary transformers 40 and 41, respectively. Further, the control signals corresponding to the calculated gap depth are respectively the frequency characteristic control circuit 43 and the recording level control circuit 44.
Is applied to the control input terminals of the recording equalization circuit 32 and the recording level adjustment circuit 33 via the, and the worn recording magnetic head 3
The adjustment is performed so that the optimum equalization characteristic and recording current level for 7 are set. The information on the gap depth calculated by the gap depth calculation circuit 42 is stored in the internal memory and held as a control signal until the next gap depth measurement.

[0013]

The conventional rotary head type magnetic recording / reproducing apparatus described above has the following problems. First, since the recording equalization circuit 32 controls the recording equalization characteristic and the recording level adjusting circuit 33 individually controls the recording current flowing through the recording magnetic head 37, the overall circuit configuration is improved. The problem is that it becomes complicated.

Second, in detecting and measuring the gap depth, two signals, that is, the signal of the terminal voltage waveform of the recording magnetic head 37 on the rotating cylinder and the signal of the current waveform of the recording driver 36 are detected. Since the rotary transformers 40 and 41 are configured to transmit to the fixed side, it is difficult to mount many circuits in a limited space on the rotary cylinder.

Thirdly, since the input of the gap depth detecting circuit 38 for detecting the terminal voltage waveform of the recording magnetic head 37 is connected in parallel to the winding of the head 37, the influence of the gap depth detecting circuit 38 is increased. Therefore, there is a problem that the resonance frequency of the head 37 is lowered and the recording characteristics are deteriorated when a digital signal having a high bit rate is recorded.

A first object of the present invention is a rotary head type magnetic recording / reproducing capable of simultaneously optimally controlling both the frequency characteristic and the recording current of the recording magnetic head according to the wear state of the recording magnetic head by a common recording equalization circuit. To provide a device.

A second object of the present invention is a rotary head type magnetic recording / reproducing capable of measuring the gap depth of the recording magnetic head by detecting only one signal and hardly affecting the resonance frequency of the head. To provide a device.

A third object of the present invention is that the frequency characteristic and the recording current of the recording magnetic head can be optimally controlled simultaneously by a common recording equalization circuit according to the wear state of the recording magnetic head, and at the same time, the recording magnetic head. SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary head type magnetic recording / reproducing apparatus capable of measuring the gap depth by detecting only one signal and hardly affecting the resonance frequency of the head.

[0019]

In order to achieve the first object of the present invention, a recording magnetic head mounted on a rotary drum and recording equalization for compensating the frequency characteristic of the recording magnetic head are provided. In a rotary head type magnetic recording / reproducing apparatus equipped with a circuit and a gap depth measuring circuit for measuring the gap depth of the recording magnetic head and controlling the recording equalization circuit according to the gap depth, recording, etc. The equalizing circuit obtains an equalized recording signal by adding a high-pass filter having a recording signal as an input, a variable gain circuit having an output of the high-pass filter as an input, and an output signal of the variable gain circuit and the recording signal. And a gap depth measuring circuit for controlling the gain of the gain varying circuit according to the gap depth of the recording magnetic head.

With this configuration, in the present invention, the gain of the variable gain circuit provided on the output side of the high-pass filter in the recording equalization circuit is controlled by the gap depth measuring circuit, so that the recording magnetic head is not worn. On the other hand, both the recording equalization characteristic for compensating the frequency characteristic of the head and the recording current flowing through the recording magnetic head can be optimally controlled at the same time, so that the circuit configuration becomes simple.

That is, specifically, when measuring the gap depth of the recording magnetic head, for example, a rectangular wave signal or a pseudo-random signal having the same data rate as the actual recording data rate is input as the recording signal. Then, the gap depth measuring circuit produces a symmetrical impulse waveform when the recording signal is a rectangular wave, and a pseudo-random recording signal when the signal is proportional to the derivative of the magnetic flux generated in the auxiliary winding wound around the recording magnetic head. When the signal is a signal, the recording and equalizing circuit is controlled so that it has an impulsive, clean eye pattern without intersymbol interference. As a result, the equalization characteristic of the recording equalization circuit is optimally controlled so that the frequency characteristic due to wear of the recording magnetic head is compensated.

Further, since the change of the optimum recording current due to the wear of the recording magnetic head is proportional to the change of the high frequency region in the change of the frequency characteristic of the head due to the wear, the level of the recording signal passed through the high pass filter in the recording equalization circuit. Is changed by the gain control of the variable gain circuit, the level of the recording signal passing through the recording equalization circuit changes in accordance with the change of the optimum recording current due to the abrasion of the recording magnetic head.

Therefore, the recording equalizer circuit controls both the change of the frequency characteristic due to the wear of the recording magnetic head and the change of the optimum recording current by the gain control of the variable gain circuit by one control signal from the gap depth measuring circuit. It can be optimized at the same time.

In order to achieve the second object of the present invention, a recording magnetic head mounted on a rotary drum, a recording equalizing circuit for compensating the frequency characteristic of the recording magnetic head, and a recording magnetic head are provided. In a rotary head type magnetic recording / reproducing apparatus provided with a gap depth measuring circuit for measuring a gap depth of a magnetic head and controlling a recording equalizing circuit according to the gap depth, the gap depth measuring circuit is a recording device. Auxiliary winding wound around the magnetic head for recording separately from the recording main winding, the auxiliary winding having a smaller number of turns than the recording main winding, a detection circuit for detecting a signal generated in the auxiliary winding, and an output of the detection circuit A gap depth calculation circuit for calculating and storing the gap depth of the recording magnetic head from the signal, and a control circuit for controlling the recording equalization circuit according to the gap depth calculated and stored by the gap depth calculation circuit. Characterized in that it has and.

As described above, according to the present invention, since the gap depth of the recording magnetic head can be measured by one gap depth measuring circuit based on the signal generated by the auxiliary winding, it is mounted on the rotary cylinder. The number of circuits is small and the circuit on the rotating cylinder can be easily mounted. Moreover, since the gap depth of the recording magnetic head is measured based on a signal from a special auxiliary winding provided separately from the recording main winding and having a small number of turns, the head depth of the recording main winding is reduced. It is possible to measure the gap depth with little effect on the resonant frequency. Further, the present invention is the third aspect.
In order to achieve the purpose of, the recording equalization circuit and the gap depth measurement circuit described above are combined.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a partial configuration of a recording side circuit of a rotary head type magnetic recording / reproducing apparatus including a recording equalization circuit and a gap depth measuring circuit according to a first embodiment of the present invention. It is a block diagram showing.

In FIG. 1, at the time of recording, a digital signal having a predetermined recording data rate, which is modulated by adding an error correction code to the digital data to be recorded and formatting, is supplied to the input terminal 10 as a recording signal, and a recording equalization circuit is provided. 11 is input. Recording equalization circuit 11
Is composed of an adder circuit 101, a high-pass filter 102 and a variable gain circuit 103, and the recording signal is given to one input of the adder circuit 101 and the high-pass filter 102. The output of the high pass filter 102 is given to the other input of the adding circuit 101 via the variable gain circuit 103. The variable gain circuit 13 is a circuit whose gain can be controlled by an external control signal, and a variable gain amplifier or a variable attenuator is used. In the case of the variable gain amplifier, the gain is 1 or more, but in the case of the variable attenuator, the gain (attenuation amount) becomes a value less than 1.

The output of the recording equalization circuit 11 is the addition circuit 101.
Is a recording signal output from a rotary transformer drive circuit 12 and a rotary transformer 13, and is supplied to a recording driver 14. The recording driver 14 is a circuit for driving the recording magnetic head 15, and supplies a recording current according to the supplied recording signal to the recording main winding 15 a of the recording magnetic head 15.

In the recording magnetic head 15, in addition to the recording main winding 15a, the number of windings is smaller than that of the main winding 15a.
Preferably, the number of turns is one-fifth or less of the number of turns of the main winding 15a,
For example, the auxiliary winding 15b having 1 or 2 turns is wound, the signal induced in the auxiliary winding 15b is detected by the gap depth detecting circuit 16, and is passed through the rotary transformer 17 to the gap depth calculating circuit 18. Is entered. The output of the gap depth calculation circuit 18 is input to the control circuit 19, and the control circuit 19 supplies a control signal to the control input terminal of the gain variable circuit 103 based on the output of the gap depth calculation circuit 18 to control the gain thereof. To do.

Next, the operation of this embodiment will be described. In the gap depth measuring mode of the recording magnetic head 15, for example, a rectangular wave signal or a pseudo random signal having the same data rate as the actual recording data rate is input to the input terminal 10 as a recording signal. This recording signal is a recording equalization circuit 1
1, the rotary transformer drive circuit 12 and the rotary transformer 13 are sequentially supplied to the recording driver 14. The recording driver 14 applies a recording current corresponding to the input recording signal to the recording main winding 15a of the recording magnetic head 15 to generate a magnetic flux, and forms a recording magnetic field by the recording signal at the tip of the gap.

Here, the frequency characteristic of the recording magnetic head 15, that is, the frequency characteristic of the magnetic flux generated by the head 15 and the frequency characteristic of the recording magnetic field, changes depending on the gap depth if the recording current is the same. The gap depth changes in inverse proportion to the amount of wear of the recording magnetic head 15. The auxiliary winding 15b wound around the recording magnetic head 15 generates a voltage signal having a waveform proportional to the derivative of the magnetic flux generated by the recording current, and this voltage signal is detected by the gap depth detection circuit 16. The signal detected by the gap depth detection circuit 16 is a voltage waveform corresponding to the gap depth of the recording magnetic head 15, and is transmitted to the gap depth calculation circuit 18 via the rotary transformer 17. , The gap depth is calculated.

Since the voltage signal detected by the gap depth detection circuit 16 is a signal from the auxiliary winding 15b proportional to the differentiation of the magnetic flux generated by the recording current as described above, when the recording signal is a rectangular wave. It has positive and negative impulse waveforms, and when the recording signal is a pseudo-random signal at the actual recording data rate, it has an impulse-like waveform that is pseudo-randomly generated in positive and negative directions. In this case, the calculation of the gap depth in the gap depth calculation circuit 18 is performed by calculating the voltage at the skirt of the trailing edge in the positive and negative impulse waveforms, or the intersymbol interference amount of the eye pattern in the pseudo-randomly generated impulse-like waveform. Is done by measuring.

The gap depth calculating circuit 18 calculates the gap depth of the recording magnetic head 15 and stores the information in the internal memory as described above, and also controls the gain variable circuit 103 via the control circuit 19. Control the gain. By controlling the gain of the variable gain circuit 103 by the gap depth calculating circuit 18 and the control circuit 19 as described above, the voltage at the trailing edge of the positive or negative impulse waveform or the intersymbol interference amount of the eye pattern is made zero. You can This was confirmed by experiments. Specifically, the gain control of the variable gain circuit 103 is performed while the recording magnetic head 15 is lapped and worn, and the gap depth calculation circuit 16 is performed.
It was confirmed that the voltage at the trailing edge of the positive and negative impulse waveforms or the intersymbol interference amount of the eye pattern was zero by observing the output of the above. Therefore,
By controlling the gain of the variable gain circuit 103 by the gap depth calculation circuit 18 and the control circuit 19, the recording magnetic head 1
The equalization characteristic of the recording equalization circuit 11 is optimally controlled so that the frequency characteristic due to wear of No. 5 is compensated.

On the other hand, the change in the optimum recording current due to wear of the recording magnetic head 15 is proportional to the change in the high frequency region of the change in frequency characteristic of the head 15 due to wear. Since the recording equalization circuit 11 changes the recording equalization characteristic (frequency characteristic) by controlling the level of the recording signal passed through the high-pass filter 102 with the variable gain circuit 103, the recording passed through the recording equalization circuit 11 is performed. The signal level changes following the change in the optimum recording current due to wear of the recording magnetic head 15. Therefore, the recording equalization circuit 11 simultaneously responds to both the change in the frequency characteristic due to the wear of the recording magnetic head 15 and the change in the optimum recording current by the gain control of the gain variable circuit 103 by one control signal from the control circuit 19. You can do it.

As described above, according to this embodiment, the recording equalization characteristic for compensating the frequency characteristic of the recording magnetic head 15 with respect to the wear of the recording magnetic head 15 in one recording equalization circuit 11 and the recording equalization characteristic in the head 15. Both of the recording currents to be supplied can be optimally controlled at the same time, and the circuit configuration is simplified.

Further, the gap depth of the recording magnetic head 15 is detected by one gap depth detection circuit 16 and the gap depth calculation circuit 18 measures the signal generated by the auxiliary winding 15b wound around the head 15. Therefore, the number of circuits to be mounted on the rotary cylinder is small, and the circuit on the rotary cylinder can be easily mounted.

Further, in order to detect the gap depth of the recording magnetic head 15, a dedicated auxiliary winding 15b is provided in addition to the recording main winding 15a.
5 has the advantage that the gap depth can be measured with almost no effect on the resonance frequency of the head 15.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the rotary head type magnetic recording / reproducing apparatus according to the embodiment. The present embodiment is an example in which two recording equalization circuits are controlled by one gap depth measuring circuit, and FIG. 2 shows a part of a two-channel recording side circuit of a rotary head type magnetic recording / reproducing apparatus. ing.

In this embodiment, in addition to the configuration shown in FIG. 1, an input terminal 20, a recording equalization circuit 21, a rotary transformer drive circuit 22, a rotary transformer 23, a recording driver 24, a recording magnetic head 25 and a control circuit. 26 is newly added. Since the other parts are the same as those in FIG. 1, the same reference numerals are given and the description thereof is omitted.

A recording signal of a channel different from the recording signal supplied to the input terminal 10 is supplied to the input terminal 20, and is input to the recording equalization circuit 21. Recording equalization circuit 21
Is composed of an adder circuit 201, a high-pass filter 202 and a variable gain circuit 203 like the recording circuit 11, and a recording signal is given to one input of the adder circuit 201 and the high-pass filter 202. High pass filter 202
Of the output of the adder circuit 201 via the variable gain circuit 203.
Given to the other input of.

The output of the recording equalizing circuit 21, that is, the recording signal output from the adding circuit 201 is supplied to the recording driver 24 through the rotary transformer drive circuit 22 and the rotary transformer 23 in sequence. The recording driver 24 is a circuit that drives the recording magnetic head 25, and applies a recording current according to the supplied recording signal to the recording main winding 25 a of the recording magnetic head 15.

Unlike the recording magnetic head 15, the recording magnetic head 25 is not wound with an auxiliary winding, and is not connected with a gap depth detecting circuit. The recording magnetic heads 15 and 25 have the same magnetic core material, structure, size, and the like, except for the presence or absence of the auxiliary winding, and the initial gap depth is also the same. The control circuit 26 is the recording equalization circuit 2
1 is a circuit for controlling the gain control circuit 1, and supplies a control signal to the control signal input of the gain variable circuit 203 based on the output of the gap depth calculation circuit 18 to control the gain thereof.

Next, the operation of this embodiment will be described. Recording equalization circuit 11, rotary transformer drive circuit 12, rotary transformer 13, recording driver 14, recording magnetic head 15, gap depth detection circuit 16, rotary transformer 1
7. The operations of the gap depth calculation circuit 18 and the control circuit 19 are exactly the same as those in the first embodiment, and the gap depth calculation circuit 18 calculates the gap depth of the recording magnetic head 15. The recording magnetic head 25 is the recording magnetic head 15.
Since the material, structure and size of the magnetic core are the same, the wear rate is the same and the gap depth is also the same. Therefore, the gap depth of the recording magnetic head 15 calculated by the gap depth calculating circuit 18 is the recording magnetic head 25.
The gap depth will always be approximately equal.

In the present embodiment, the output of the gap depth calculating circuit 18 is supplied to the variable gain circuit 2 via the control circuit 26.
03 control input terminal to control its gain. The recording equalization circuit 21 controls the gain of the variable gain circuit 203 by the control circuit 26, so that the recording equalization characteristic and the recording flow to the recording magnetic head 25 according to the gap depth of the recording magnetic head 15. Change the current. In this case, since the gap depth of the recording magnetic head 25 is almost the same as that of the recording magnetic head 15 as described above, the recording equalization characteristic of the recording equalization circuit 21 and the recording current flowing through the recording magnetic head 25. Is a recording magnetic head 25
It will also correspond to changes in the gap depth.

The recording signal output from the recording equalization circuit 21 is supplied to the recording magnetic head 25 through the rotary transformer drive circuit 22, the rotary transformer 23 and the recording driver 24 in this order, and therefore the recording magnetic head 25.
Like the recording magnetic head 15, the recording can always be performed in the optimum recording state.

As described above, according to the present embodiment, in the two-channel rotary head type magnetic recording / reproducing apparatus, the same effect as that of the previous embodiment can be obtained, and the magnetic properties of the two recording magnetic heads 15 and 25 are increased. If the core has the same material, structure, size, etc., the number of gap depth measuring circuits can be reduced to one, that is, less than the number of channels, and there is an advantage that the configuration becomes simpler.

The present invention is not limited to the above-described embodiment, and various modifications can be carried out without departing from the scope of the invention. For example, although the recording equalization circuit and the gap depth calculation circuit are arranged on the fixed side of the rotary head type magnetic recording / reproducing apparatus in the above embodiment, the recording equalization circuit and the gap depth measurement circuit are mounted on the rotary cylinder. It is also possible to reduce the number of rotary transformers. Further, in the second embodiment, one gap depth measuring circuit is used for two recording magnetic heads, but one gap depth measuring circuit is used for three or more recording magnetic heads. Alternatively, three or more recording equalization circuits may be controlled by.

[0048]

As described above, according to the present invention, the gain of the variable gain circuit provided on the output side of the high-pass filter in the recording equalization circuit is controlled by the gap depth measuring circuit, so that the recording magnetic field is reduced. Since both the recording equalization characteristic for compensating the frequency characteristic of the head against the wear of the head and the recording current flowing in the recording magnetic head can be optimally controlled at the same time, the circuit configuration becomes simple.

Further, according to the present invention, the gap depth of the recording magnetic head can be measured by one gap depth measuring circuit based on the signal generated by the auxiliary winding.
The number of circuits mounted on the rotary cylinder is small, and the circuit on the rotary cylinder can be easily mounted. Moreover, since the gap depth of the recording magnetic head is measured based on a signal from a special auxiliary winding provided separately from the recording main winding and having a small number of turns, the head depth of the recording main winding is reduced. It is possible to measure the gap depth with little effect on the resonant frequency.

[Brief description of drawings]

FIG. 1 is a block diagram showing a partial configuration of a recording side circuit of a rotary head type magnetic recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a part of a recording side circuit of a rotary head type magnetic recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a part of a recording side circuit of a rotary head type magnetic recording / reproducing device having a conventional magnetic head wear state detecting device and a recording equalizing circuit.

[Explanation of symbols]

10, 20, 31 ... Recording signal input terminals 11, 21, 32 ... Recording equalization circuit 12, 22, 24 ... Rotary transformer drive circuit 13, 17, 23, 35, 40, 41 ... Rotary transformer 14, 24, 36 ... Recording driver 15, 25, 37 ... Recording magnetic head 15a ... Recording main winding 15b ... Gap depth detection auxiliary winding 16, 38, 39 ... Gap depth detection circuit 18, 42 ... Gap depth calculation circuit 19 , 26 ... Control circuit 43 ... Frequency characteristic control circuit 44 ... Recording level control circuit 101, 201 ... Addition circuit 102, 202 ... High-pass filter 103, 203 ... Gain variable circuit

Claims (5)

[Claims] 1. A recording magnetic head mounted on a rotating drum, a recording equalizing circuit for compensating the frequency characteristic of the recording magnetic head, and a gap depth of the recording magnetic head is measured to measure the gap. In a rotary head type magnetic recording / reproducing apparatus provided with a gap depth measuring circuit for controlling the recording equalization circuit according to the depth, the recording equalization circuit has a high-pass filter receiving a recording signal, A gap variable measuring circuit having an output of a high-pass filter as an input; and an adder circuit for adding an output signal of the gain variable circuit and the recording signal to obtain an equalized recording signal, the gap depth measuring circuit Is a rotary head type magnetic recording / reproducing apparatus, wherein the gain of the gain varying circuit is controlled according to the gap depth of the recording magnetic head. 2. A recording magnetic head mounted on a rotary drum, a recording equalizing circuit for compensating the frequency characteristic of the recording magnetic head, and a gap depth of the recording magnetic head measured to measure the gap. A rotary head type magnetic recording / reproducing apparatus including a gap depth measuring circuit for controlling the recording equalizing circuit according to a depth, wherein the gap depth measuring circuit is wound around the recording magnetic head for recording. Auxiliary winding having a smaller number of turns than the recording main winding wound separately from the wire, a detection circuit for detecting a signal generated in the auxiliary winding, and an output signal of the detection circuit from the recording magnetic head of the recording magnetic head. A gap depth calculation circuit for calculating and storing the gap depth, and a control circuit for controlling the recording equalization circuit according to the gap depth calculated and stored by the gap depth calculation circuit. A rotary head type magnetic recording / reproducing apparatus characterized by: 3. A plurality of recording magnetic heads mounted on a rotating drum, a plurality of recording equalizing circuits for respectively compensating frequency characteristics of the plurality of recording magnetic heads, and a gap of the recording magnetic heads. In a rotary head type magnetic recording / reproducing apparatus equipped with a gap depth measuring circuit for measuring a depth and controlling the equalization characteristic of the recording equalizing circuit according to the gap depth, the gap depth measuring circuit is An auxiliary winding having a smaller number of turns than the recording main winding wound around at least one recording magnetic head of the plurality of recording magnetic heads separately from the recording main winding, and the auxiliary winding. A detection circuit for detecting the generated signal, a gap depth calculation circuit for calculating and storing the gap depth of the recording magnetic head wound with the auxiliary winding from the output signal of the detection circuit, and this gap. A rotary head type magnetic recording / reproducing apparatus comprising: a plurality of control circuits that respectively control the plurality of recording equalization circuits according to the gap depth calculated and stored by the depth calculation circuit. 4. A recording magnetic head mounted on a rotary drum, a recording equalizing circuit for compensating the frequency characteristics of the recording magnetic head, and a gap depth of the recording magnetic head is measured to measure the gap. In a rotary head type magnetic recording / reproducing apparatus equipped with a gap depth measuring circuit for controlling the recording equalization circuit according to the depth, the recording equalization circuit includes a high-pass filter having a recording signal as an input, A gap variable measuring circuit having an output of a high-pass filter as an input; and an adder circuit for adding an output signal of the gain variable circuit and the recording signal to obtain an equalized recording signal, the gap depth measuring circuit Is an auxiliary winding wound around the recording magnetic head separately from the recording main winding and having a smaller number of turns than the recording main winding; and a detection circuit for detecting a signal generated in the auxiliary winding. Detection times A gap depth calculating circuit for calculating and storing the gap depth of the recording magnetic head from the output signal of the recording head, and the gain of the gain varying circuit according to the gap depth calculated and stored by the gap depth calculating circuit. And a control circuit for controlling the magnetic head. 5. A plurality of recording magnetic heads mounted on a rotary drum, a plurality of recording equalizing circuits for compensating frequency characteristics of the plurality of recording magnetic heads, and a gap of the recording magnetic head. In a rotary head type magnetic recording / reproducing apparatus equipped with a gap depth measuring circuit for measuring a depth and controlling an equalizing characteristic of the recording equalizing circuit according to the gap depth, the recording equalizing circuit comprises: A high-pass filter having a recording signal as an input, a gain variable circuit having an output of the high-pass filter as an input, and an addition circuit for obtaining an equalized recording signal by adding an output signal of the gain variable circuit and the recording signal. The gap depth measuring circuit has a recording main winding wound around at least one recording magnetic head of the plurality of recording magnetic heads separately from the recording main winding. An auxiliary winding having a small number of windings, a detection circuit for detecting a signal generated in the auxiliary winding, and a gap depth of a recording magnetic head wound with the auxiliary winding is calculated from an output signal of the detection circuit. And a plurality of control circuits for respectively controlling the gains of the gain variable circuits in the plurality of recording equalization circuits according to the gap depths calculated and stored by the gap depth calculation circuit. A rotary head type magnetic recording / reproducing apparatus comprising: