JP3353493B2 - Load measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load measuring device for measuring a load which a magnetic recording medium receives from a magnetic tape when the magnetic recording medium slides on the magnetic head.

[0002]

2. Description of the Related Art Usually, a video tape recorder (VTR) is used.
Is mounted with a rotary magnetic head device in which a magnetic head is provided on the peripheral surface of a rotary drum. In this case, recording and reproduction of video, audio, and the like are performed by sliding the magnetic recording medium sliding surface of the magnetic head on a video tape that is a magnetic recording medium.

Since the magnetic head comes into sliding contact with the video tape, the wear of the head on the sliding surface of the magnetic recording medium as the magnetic head is repeatedly used, the hitting characteristic, and the output decrease accompanying the use of the magnetic head are reduced. Inevitably, there is a problem that is affected by the surface pressure exerted on the surface. Therefore, in order to study the above problem, it is necessary to quantitatively and accurately measure the surface pressure.

Conventionally, it has been necessary to use a technique called aging in order to quantitatively measure the head wear and the like, and there has been a drawback that it takes a lot of time and cost. Therefore, recently, as a load measuring device for measuring a surface pressure applied to a magnetic head of a rotary magnetic head device, a device that captures and measures a contact load as a change in an electric resistance value due to a deformation of a member has been considered. . As shown in FIG. 8, the load measuring device includes a jig 101 having one end 101a fixed to a predetermined position on a rotating drum 111, and a second end 101 of the jig 101.
b, a substantially L-shaped support 1 having an upper end portion 102a fixed thereto
02. Here, the support 102
Is provided with a strain gauge 103 made of a semiconductor in the vicinity of the upper end portion 102a and a head chip 104 for slidingly contacting the video tape at the front end portion.

When the rotating drum 111 is driven to rotate and the tip of the head chip 104 comes into sliding contact with the video tape and receives a surface pressure, the head chip 104 is pressed and the upper end 102a of the support 102 is supported by the support 102. A slight distortion occurs due to the applied stress. At this time, the electric resistance of the support 102 changes due to the strain, and the change in electric resistance is measured as a voltage change by the highly sensitive strain gauge 103. Thus, the surface pressure that the head chip 104 receives from the video tape during the sliding contact can be measured.

[0006]

However, in order to detect the distortion generated in the support body 102 when the head chip 104 is pressed from the video tape as described above, the load measuring device assumes a magnetic head by this measuring operation. The position of the head chip 104 and the position of the video tape inevitably fluctuate. Therefore, it is difficult to say that the head chip 104 slides on the video tape under almost the same conditions as the slide with the magnetic head during the actual running of the video tape.

[0007] Therefore, in order to approach the actual conditions as much as possible, the rigidity of the support 102 is increased to increase the rigidity of the support 10.
It is conceivable to suppress the distortion of No. 2 in this case, but in this case, there is a problem that the structure of the support 102 is inevitably larger than that of the rotating drum 111 and the weight is increased.

In addition, since the amount of strain of the support 102 is detected as the electric resistance value of the strain gauge 103, it is necessary to use an unstable interface such as a slip ring when directly measuring the strain.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a magnetic head which receives a surface pressure from a magnetic recording medium when the magnetic head slides on the magnetic recording medium. To develop a better magnetic head and magnetic recording medium by clarifying the sliding contact between the magnetic head and the magnetic recording medium, while enabling the direct measurement of the load caused by the magnetic head in a running state that is extremely equivalent to the actual machine. It is an object of the present invention to provide a load measuring device that can help the above.

[0010]

An object of the present invention is a load measuring device for measuring a contact load mainly in a running state between a magnetic head and a tape type magnetic recording medium.

The load measuring device of the present invention has a magnetic core made of a magnetic material such as ferrite and converting a contact load to magnetostriction, and a signal supply coil for supplying a reference signal to the magnetic core. A signal detection coil for extracting a detection signal is wound. The load detecting means is mainly mounted on a rotating drum.

At this time, the magnetic core may be formed by integrally forming a pair of magnetic core halves. That is, in this case, the load detecting means is configured by forming a closed magnetic circuit as a magnetic core by joining a pair of magnetic core halves, and applying a winding to each magnetic core half to form each of the coils. .

In the load measuring device, reference signal generating means for supplying a reference signal to the signal supply coil of the load detecting means, and a detection signal which is a response to the reference signal is measured from the signal detecting coil. And a detection signal measuring means.

Here, when a reference signal is supplied to the signal supply coil, lines of magnetic force are generated in the magnetic core, and a detection signal is applied to the signal detection coil. In this state, when the magnetic recording medium sliding surface of the magnetic core slides on the magnetic recording medium and a contact load is applied, the magnetic permeability of the magnetic core fluctuates, and the signal supply coil changes from the signal supply coil to the signal detection coil. The signal transmission efficiency to the Therefore, the ratio between the reference signal and the detection signal changes according to the contact load amount, and the contact load amount is measured by detecting the detection signal at this time.

In the present invention, it is assumed that the reference signal and the detection signal are mainly AC signals, and the input and output of the reference signal and the detection signal are performed via a rotary transformer.

[0016]

The load measuring device according to the present invention has a magnetic core made of a magnetic material and converting a contact load into magnetostriction.
A signal supply coil for supplying a reference signal and a signal detection coil for extracting a detection signal are wound around the magnetic core. That is, the load detecting means has substantially the same shape as a normal magnetic head, and the magnetic head slides on the magnetic recording medium when the magnetic recording medium travels in an actual machine. Since the above-mentioned load detecting means can create a state almost identical to a state where a contact load is applied to the surface, the measurement result of the contact load with the magnetic recording medium by the load detecting means is substantially the same as the contact load in the actual machine. Can be considered as Therefore, it is possible to quantitatively and extremely accurately measure the contact load as equivalent to an actual machine.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a load measuring device according to the present invention will be described below in detail with reference to the drawings.

The load measuring device of this embodiment measures a contact load in a running state between a magnetic head and a tape type magnetic recording medium.

Normally, a video tape recorder (VTR) is equipped with a rotary magnetic head device in which a magnetic head is provided on a peripheral surface of a rotary drum. In the magnetic head, as shown in FIG. 1, a pair of magnetic core halves 11, 12 made of a magnetic material such as ferrite are butted via a gap material 16 made of a non-magnetic material.
And a magnetic gap g is formed. Then, a winding is applied to a winding groove 14 provided in the magnetic core 12 to form a coil 15. The magnetic head 1
In No. 1, recording on a video tape which is a magnetic recording medium is performed by a leakage magnetic field generated near the magnetic gap g.
Perform playback.

In the load measuring device according to the present embodiment, the load measuring means, which is a component thereof, is formed in substantially the same shape as the magnetic head 11. That is, as shown in FIG. 2, the load measuring means is configured such that a pair of magnetic core halves 1 and 2 made of a magnetic material such as ferrite are joined together to form a magnetic core 3, Windings are applied to the magnetic core halves 1 and 2 to form coils 4 and 5 for signal supply and signal detection, respectively. Therefore, in the load measuring means, a minute transformer is formed by the magnetic core 3 and the coils 4 and 5.

Here, the difference between the load measuring means and the magnetic head is that the magnetic core halves 1 and 2 have a magnetic gap g.
Core 3 without contact with each other
Therefore, a closed magnetic path is formed without generating a leakage magnetic field, and the load measuring means has a structure that is not influenced by a magnetic recording medium or the like. While one coil is provided, two points are provided in the load measuring means, that is, one coil is formed on each of the magnetic core halves 1 and 2.

As shown in FIG. 3, the load measuring means is mounted on the head base 6 and mounted on the rotating drum 7 on the sliding surface a of the magnetic recording medium, as in the case of a normal magnetic head.
Are provided so as to face the peripheral surface 7a of the rotary drum 7, and the rotary drum 7 is further installed on a rotary drum type magnetic head device 21 as shown in FIG.

As shown in FIG. 4, the load measuring device includes a reference signal generating means 22 for supplying a reference signal to one coil 4 of the load detecting means, and the reference signal And a detection signal measuring means 23 for measuring a detection signal which is a response to the above, and are electrically connected to the rotary drum type magnetic head device 21 respectively. The input and output of the reference signal and the detection signal to and from the reference signal generating means 22 and the detection signal measuring means 23 in the load measuring means are performed by a rotary electrically connected to a rotary transformer connection portion 8 provided on the rotating drum 7. This is performed via a transformer (not shown).

Next, the principle of operation of the load measuring device will be described. First, FIG. 5 shows a state in which no load from the video tape is applied to the load measuring means. As shown in the figure, when an AC reference signal is applied to the coil 4 wound around the magnetic core half 1 from the reference signal generating means 22, a magnetic field line M is generated in the magnetic core half 1, and the magnetic field line M is generated.
As a result, a detection signal is generated in the coil 5 of the magnetic core half 2 and detected by the detection signal measuring means 23.

Then, the video tape is run in a state where the AC reference signal is applied from the reference signal generating means 22 to the coil 4 wound around the magnetic core half 1, and the magnetic recording medium sliding surface of the load measuring means is moved. a, the magnetic conductivity of the magnetic core 3 changes due to the contact load N applied from the video tape T to the sliding surface a of the magnetic recording medium, as shown in FIG. Therefore, the signal transmission efficiency from the coil 4 to the coil 5 varies, and the ratio of the detection signal to the reference signal also changes. By detecting the detection signal by the detection signal measuring means 23, the contact load N is measured.

As described above, in the load measuring device of the present embodiment, the pair of magnetic core halves 1 and 2 are put together to form the magnetic core 3 to form a closed magnetic path, and the magnetic core halves 1 and 2 are formed. 2 is wound on each coil, and each coil 4, 5
Are formed to constitute the load detecting means. That is, the load detecting means has substantially the same shape as a normal magnetic head, and the magnetic head when the video tape as the magnetic recording medium is running and the video tape are in sliding contact with each other in the actual VTR, and Since a state almost identical to a state in which a contact load is applied to the sliding surface of the magnetic recording medium can be created by using the above-mentioned load detecting means, the measurement result of the contact load with the video tape by the load detecting means is used to determine the contact load in the actual machine. It can be considered that the load N is substantially the same. Therefore, it is possible to quantitatively and very accurately measure the contact load almost equivalently to the actual machine.

Here, a modified example of the load measuring device according to the above embodiment will be described. The load measuring device of this modification has substantially the same configuration as that of the above embodiment, but differs in that the method of applying the reference signal and the method of detecting the detection signal in the load measuring means are different. In this modification, the same members and the like as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 7, in the load measuring device of the above-described modified example, the load measuring device,
Unlike a structure in which the magnetic core halves are integrally formed as in the case of the magnetic core 3, the magnetic core 3 manufactured from one substrate
1. Holes 32a to 32d are formed at four positions on the main surface of the magnetic core 31 like vertexes of a quadrilateral, and winding is performed along a diagonal line formed by the holes 32a and 32d. Is formed,
A coil 34 is formed by winding the coil 33 along a diagonal line formed by the holes 32b and 32c so as to be substantially orthogonal to the main surface on the main surface. Here, coil 3
Reference numeral 3 corresponds to the coil 4 in the above embodiment, and the coil 34 corresponds to the coil 5. The reference signal generating means 22 and the detection signal measuring means 23 are electrically connected to the coils 33 and 34, respectively.

In the above load measuring device, the magnetic core 31
When an AC reference signal is applied to the coil 4 wound around the magnetic core half 1 on the coil 33, magnetic lines of force M are generated as shown in the figure, but when no load is applied from the video tape, the direction of the magnetic lines of force M is Since the coil 34 is substantially parallel to the winding direction, no voltage as a detection signal is generated in the coil 34. In this state, when the video tape is run and slid on the magnetic recording medium sliding surface a of the load measuring means, the magnetic conductivity of the magnetic core 3 is increased by the contact load applied from the video tape to the magnetic recording medium sliding surface a. The detection signal that changes and is proportional to the amount of contact load is applied to the coil 34. By detecting the detection signal by the detection signal measuring means 23, the contact load is measured.

The load measuring device of this modification also has a magnetic core 31 formed from one substrate and having a closed magnetic path formed thereon, similarly to that of the above embodiment, and a winding formed on the magnetic core. The coils 33 and 34 are formed by applying windings to the holes 32a to 32d, respectively.
Therefore, in the VTR of the actual machine, the state in which the magnetic head when the video tape as the magnetic recording medium runs and the video tape slides into contact with each other and a contact load is applied to the magnetic recording medium sliding surface of the magnetic head is almost the same. Since it can be created using the load detecting means, the measurement result of the contact load with the video tape by the load detecting means can be regarded as substantially the same as the contact load in the actual machine. Therefore, it is possible to quantitatively and very accurately measure the contact load almost equivalently to the actual machine.

[0031]

As is clear from the above description, according to the load measuring device of the present invention, the surface pressure received from the magnetic recording medium when the magnetic head slides on the tape-type magnetic recording medium. Of the magnetic head and the magnetic recording medium can be directly measured in the running state, which is extremely equivalent to the actual machine, and the state of sliding contact between the magnetic head and the magnetic recording medium is clarified to assist in the development of better magnetic heads and magnetic recording media. It can be.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a normal magnetic head.

FIG. 2 is a front view schematically showing a load measuring unit which is a component of the load measuring device according to the embodiment.

FIG. 3 is a schematic diagram illustrating a load measuring device according to the present embodiment.

FIG. 4 is a front view schematically showing a state where load measuring means is mounted on a rotating drum.

FIG. 5 is a front view schematically showing a state where a load from a magnetic recording medium is not applied to a load measuring unit.

FIG. 6 is a front view schematically showing a state where a load from a magnetic recording medium is applied to a load measuring unit.

FIG. 7 is a front view schematically showing a load measuring unit according to a modified example.

FIG. 8 is a perspective view schematically showing load measuring means which is a component of a conventional load measuring device.

[Explanation of symbols]

 1, 2 magnetic core half 3, 31 magnetic core 4, 5, 33, 34 coil 7 rotating drum 22 reference signal generating means 23 detection signal measuring means

Claims (5)

(57) [Claims] 1. A magnetic sensor comprising: a magnetic core made of a magnetic material for converting a contact load into magnetostriction; a signal supply coil for supplying a reference signal and a signal detection coil for extracting a detection signal wound on the magnetic core; A load measuring device characterized in that: 2. The load measuring device according to claim 1, wherein the measured contact load is a contact touch load in a running state of the magnetic tape. 3. The load measuring device according to claim 1, wherein the magnetic core is formed by integrally joining a pair of magnetic core halves. 4. It has reference signal generation means for supplying a reference signal to a signal supply coil of a load detection means, and detection signal measurement means for measuring a detection signal which is a response to the reference signal from the signal detection coil. The load measuring device according to claim 1, wherein: 5. The load measuring device according to claim 1, wherein the reference signal and the detection signal are AC signals, and the input and output of the reference signal and the detection signal are performed via a rotary transformer.