JPH09243723A - Sensor mounting correcting device for magnetic measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the center of a Hall element mounted on a probe by minutely moving the Hall element within magnetic fields differed in distribution to regularly measure the output according to the distribution of magnetic fields, and judging the arrangement position at the present time of the Hall element from the degree of change of the output. SOLUTION: Within a space surrounded by electromagnetic coils 3A, 3B, 3C, 3D, a distribution of electric fields is formed in lateral direction in x-y plane to each electromagnetic coil 3A-3D. A probe 4 is positioned vertically (z-axially) to the x-y plane. The probe 4 is moved in x-direction so as to cross the front surface of S-pole of the coil 3A, then turned to y-direction, and moved so as to cross the front surface of N-pole of the coil 3B. The output from the Hall element of the probe 4 is regularly detected to track the change of the output. The arrangement position of the Hall element at the present time to the probe 4 forming the support body can be judged from the degree of change of the output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor mounting and calibrating device for a magnetic measuring device, and more particularly to a sensor mounting and calibrating device for a magnetic measuring device for detecting a magnetic force in a three-dimensional space in each direction and in each direction. .

[0002]

2. Description of the Related Art A magnetic measuring device is a device for detecting how much and in what direction a magnetic force is generated in one space.

When detecting these three-dimensionally, the amounts of the magnetic forces in the x, y, and z directions are detected by magnetic sensors provided separately, and the detected amounts are vectorized. It is designed to be synthesized.

Such a magnetic measuring device is used, for example, for measuring a magnetic field distribution in a deflection yoke provided in a cathode ray tube.

In this case, a Hall element is generally used as the magnetic sensor, and this Hall element is composed of extremely small pellets and is generated only in the direction perpendicular to the main surface thereof. It is configured to be able to output a voltage value corresponding to the amount of magnetic force present.

Since the Hall element is made of extremely small pellets as described above, it is supported by, for example, the tip of a rod-shaped support, and is itself configured as a probe incorporating the Hall element. There is.

Here, since the Hall element in the probe indirectly measures the amount of magnetic force at the position where the probe is arranged, the Hall element is accurately arranged at a predetermined position with respect to the probe. Installation will be required.

[0008]

However, in the conventional magnetic measuring devices, since the Hall element, which is the magnetic sensor, is a very small pellet, it is extremely difficult to accurately place it in a predetermined position. Many were left at positions that were slightly offset from their intended positions, and no solution was found.

Therefore, if the center of the Hall element attached to the probe (the point of the highest sensitivity) can be accurately detected, the present inventors should calibrate the arrangement of the Hall element from the detection result. As a result, they have found that the Hall element can be accurately arranged at a predetermined position, and have completed the present invention.

Therefore, it is an object of the present invention to provide a sensor mounting calibration device for a magnetic measuring device which can accurately detect the center of a Hall element mounted on a probe despite its simple structure.

[0011]

In order to achieve such an object, the present invention detects, for example, the center of a Hall element of a magnetic measuring apparatus including a Hall element for measuring the strength of a magnetic field in the x direction. In this case, as a means for determining at least the center in the x direction in the magnetically shielded space, at least a magnetic field generating section for generating a magnetic field in the left-right direction on the xy plane and the distribution of the magnetic field are crossed. Thus, it has a moving means for finely moving the hall element in the x direction, and a detecting means for detecting a time point when the output in the moving process of the hall element by the moving means becomes 0, y
As means for determining the center of the direction, a magnetic field generating portion for generating a magnetic field in the left-right direction in at least the xy plane is generated, and the Hall element is arranged so as to cross the distribution of the magnetic field.
The moving means for finely moving in the direction, and the detecting means for detecting the time point when the output of the moving means has the maximum value in the moving process of the hall element. In the left and right direction, a magnetic field generating portion, a moving means for slightly moving the Hall element in the z direction across the distribution of the magnetic field, and a moving process of the Hall element by the moving means. It is characterized in that it has a detecting means for detecting a time point when the output reaches a maximum value.

The sensor mounting calibration device of the magnetic measuring device configured as described above moves the Hall element finely across the magnetic field into a magnetic field having a different distribution by the magnetic field generating unit, and adjusts the distribution of the magnetic field. Always measure the output according to
The basic idea is to determine the current position of the Hall element (with respect to the probe serving as the support) from the degree of change in the output.

The position of the Hall element corresponds to, for example, the distance from the reference position, and this distance is stored as information and is used later when the position of the Hall element with respect to the probe is constructed. Like

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 is a schematic configuration diagram showing an embodiment of a sensor mounting calibration device of a magnetic measurement device according to the present invention.

In FIG. 1A, first, there is a cylindrical shield 1 having a central axis in the z direction in the figure. The cylindrical shield 1 functions as a geomagnetic shield for shielding the inside from the influence of geomagnetism.

The shield 1 is completely closed at one of its both ends and is closed at the other end except for a portion having an opening 1A formed of a small circle centered on its central axis. There is. The reason why the opening 1A is provided will be described in detail later.

A circular core 2 is provided in the shield 1 around its center in the z-axis direction.
The outer periphery is arranged so as to contact the inner wall of the shield 1.

Further, the circular core 2 has an electromagnetic coil 3
Four A, 3B, 3C, and 3D are attached, and these electromagnetic coils 3A, 3B, 3C, and 3D are two of those electromagnetic coils 3B, 3D as shown in the plan view of FIG.
On the x-axis, one end is supported by the circular core 2 and the other ends are arranged to face each other. in this case,
In the figure, the other ends of the electromagnetic coils 3B and 3D facing each other are N poles.

Then, the other two remaining electromagnetic coils 3
One end of each of A and 3C is supported by the circular core 2 on the y axis, and the other ends are arranged to face each other. In this case, in the figure, the other ends of the electromagnet coils facing each other are S poles.

As a result, the electromagnetic coils 3A, 3B, 3
In the space surrounded by C and 3D, an electric field distribution is formed in the left-right direction in the xy plane and an electric field distribution is formed in the up-down direction in the xz plane for each electromagnetic coil.

Then, in this way, each electromagnetic coil 3A, 3
In the space on the xy plane surrounded by B, 3C, and 3D, the probe 4 is arranged so as to be positioned perpendicular (z axis) to the plane. The probe 4 has a hall element mounting portion at the tip thereof located in a plane including the electromagnetic coils 3A, 3B, 3C, 3D, and the other end thereof having the opening 1A of the shield 1.
It is arranged to be extended through.

In this case, the slide shield 5 is attached to the probe 4 at the opening A of the shield 1, and the slide shield 5 completely closes the opening 1A.

The probe 4 is supported at its other end by a mechanism (not shown) (for example, an xyz table) so that the probe 4 can freely move within the shield 1 in the x, y, and z directions. It has become.

That is, the probe 4 is moved in the x direction across the front surface of the S pole of the electromagnetic coil 3A, and then in the y direction, as shown by the dotted line in FIG. It is adapted to move so as to cross the front surface of the N pole of the electromagnetic coil 3B. Then, after that, the electromagnetic coil 3B returns to the N pole of the electromagnetic coil 3B so as to face the N pole, and moves in the z direction to cross the N pole front surface of the electromagnetic coil 3B.

From this, the opening 1A provided in the shield 1 has a diameter that does not hinder the movement of the probe 4, and the slide shield 5 attached to the probe 4 always closes the opening 1A. It is a big one.

In this case, the output from the Hall element of the probe 1 is constantly detected and the change in the output is tracked.

Next, one embodiment of the method of using the sensor mounting calibration device of the magnetic measuring device thus constructed will be described below.

First, this device can detect the center of the Hall element of each probe for detecting the magnetic force in each of the x, y, and z directions.

Here, FIG. 2A shows a probe 4 for detecting a magnetic force in the x direction, and the minimum pellet-shaped Hall element 6x is arranged so that its main surface is orthogonal to the x axis. There is. Hereafter, such a probe is attached to the x probe 4
Called. Further, FIG. 2B shows the probe 4 for detecting the magnetic force in the y direction, and the minimum pellet-shaped Hall element 6y is arranged so that its main surface is orthogonal to the y axis. Hereinafter, such a probe is referred to as a y-probe 4. Further, FIG. 2C shows the probe 4 for detecting the magnetic force in the z direction, and the minimum pellet-shaped Hall element 6z is arranged so that its main surface is orthogonal to the z axis. Hereinafter, such a probe is referred to as a z-probe 4.

When each probe 4 as described above is arranged in the sensor mounting calibration device of the magnetic measuring device as shown in FIG. 1, the orientations of the Hall elements 6x, 6y, 6z are set to correspond to the respective axes. It will be inserted with matching.

A method of finding the center of the Hall element for each probe will be described below with reference to FIG.

(1) In the case of x probe 4 First, the Hall element 6x in the probe 4 that crosses the electromagnetic coil 3A is a circular arc in the left-right direction, especially in the xy plane, of the magnetic force generated from the S pole of the electromagnetic coil 3A. It will cut the magnetic force generated in the shape.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, there is no magnetic force that passes through the main surface of the Hall element at right angles, and therefore the Hall element 6x.
The output from is 0.

That is, at this point, the center of the Hall element 6x in the x-axis direction becomes clear.

The position of the Hall element 6x in this case corresponds to the distance from the reference position (on the x-axis), and this distance is stored as information, and then the Hall element 6x with respect to the probe. It will be used when configuring the position. This method is the same in the following description.

Then, the Hall element 6x in the probe 4 which traverses the electromagnetic coil 3B is connected to the N of the electromagnetic coil 3B.
Among the magnetic forces generated from the poles, the magnetic force generated in an arc shape in the left-right direction is cut particularly in the xy plane.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element 6x orthogonally becomes the maximum, and therefore the output from the Hall element becomes the maximum.

That is, at this point, the center of the Hall element 6x in the y-axis direction is known.

Further, at this point, by moving the probe 4 in the vertical direction (z-axis direction),
The Hall element 6x in the probe 4 that traverses the electromagnetic coil 3B cuts the magnetic force generated from the N pole of the electromagnetic coil 3B, particularly, the magnetic force generated in the vertical direction in the xz plane.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element 6x orthogonally becomes the maximum, and therefore the output from the Hall element 6x becomes the maximum.

That is, at this point, the center of the Hall element 6x in the z-axis direction is known.

(2) In case of y-probe 4 First, the Hall element 6y in the probe 4 which crosses the electromagnetic coil 3A has a circular arc in the left-right direction particularly in the xy plane among the magnetic forces generated from the S pole of the electromagnetic coil 3A. It will cut the magnetic force generated in the shape.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element 6y at right angles becomes maximum, and therefore the output from the Hall element 6y becomes maximum.

That is, at this point, the center of the Hall element 6y in the x-axis direction is known.

Next, at this time point, the Hall element 6 in the probe 4 which crosses the electromagnetic coil 3A is moved by moving the probe 4 in the vertical direction (z-axis direction).
Of the magnetic forces generated from the N pole of the electromagnetic coil 3A, y cuts off the magnetic force generated in an arc shape in the vertical direction particularly on the xz plane.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element 6y at right angles becomes maximum, and therefore the output from the Hall element 6y becomes maximum.

That is, at this point, the center of the Hall element 6y in the z-axis direction is known.

Further, the Hall element 6y in the probe 4 which traverses the electromagnetic coil 3B is designed to cut off the magnetic force generated from the N pole of the electromagnetic coil 3B particularly in the arc shape in the left-right direction on the xy plane. become.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, there is no magnetic force that passes through the main surface of the Hall element 6y at right angles, and therefore the output from the Hall element 6y becomes zero.

That is, at this point, the center of the Hall element 6y in the y-axis direction is known.

(3) In case of z probe 4 First, the Hall element 6z in the probe 4 which traverses the electromagnetic coil 3A has an arc in the left-right direction in the magnetic force generated from the S pole of the electromagnetic coil 3A. It will cut the magnetic force generated in the shape.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force passing orthogonally to the main surface of the Hall element 6z becomes maximum, and therefore the output from the Hall element 6z becomes maximum.

That is, at this point, the center of the Hall element 6z in the x-axis direction is known.

Then, the Hall element 6z in the probe 4 which traverses the electromagnetic coil 3B is connected to the N of the electromagnetic coil 3B.
Among the magnetic forces generated from the poles, the magnetic force generated in an arcuate shape in the vertical direction is cut particularly in the xz plane.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element 6z orthogonally becomes the maximum, and therefore the output from the Hall element 6z becomes the maximum.

That is, at this point, the center of the Hall element 6z in the y-axis direction is known.

Further, at this point, the probe 4 is moved in the vertical direction (z-axis direction),
The Hall element 6z in the probe 4 that crosses the electromagnetic coil 3B cuts the magnetic force generated from the N pole of the electromagnetic coil 3B, particularly in the vertical direction in the xz plane, in the form of an arc.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, there is no magnetic force that passes through the main surface of the Hall element 6z at right angles, so that the output from the Hall element 6z becomes zero.

That is, at this point, the center of the Hall element 6z in the z-axis direction is known.

In the above-mentioned embodiment, an electromagnetic coil is used as the magnet arranged in the shield, but it is needless to say that it is not limited to this and may be a permanent magnet, for example. The point is that the magnetic field generating means should be provided.

In the above-described embodiment, the pole surface of the magnetic field generating means has a flattened shape with a certain area, but the invention is not limited to this, and the tip is sharp. It goes without saying that it may be a so-called magnetic pin or the like in the shape of a sheet.

Example 2. FIG. 4 is a schematic configuration diagram showing another embodiment of the sensor mounting calibration device of the magnetic measurement device according to the present invention. In addition, the same figure (a) is a top view and the same figure (b).
FIG. 4B is a sectional view taken along line bb of FIG.

The apparatus shown in the figure shows an apparatus capable of finding the center of the Hall element in each of the probes, particularly the x probe and the y probe.

The structure is basically the same as that shown in FIG. 1, but the structure of the magnetic field generator is simplified.

That is, the inner wall of the shield 1 is provided with three magnetic field generating portions 7A, 7B and 7C at intervals of 90 ° from the central axis of the shield 1.

First, a first magnetic field generator 7A is provided on the inner wall surface parallel to the x-axis by passing currents in opposite directions to two adjacent conductive lines extending in the z-axis direction. A second magnetic field generation unit 7B is provided on the inner wall surface parallel to the y-axis by passing currents in opposite directions to two adjacent conductive wires extending in the z-axis direction. Further, a second magnetic field generating section formed by passing currents in opposite directions to two adjacent conductive wires extending in the y-axis direction on the inner wall surface parallel to the y-axis facing the second magnetic field generating section 7B. 7C is provided.

Here, the magnetic force from each of the magnetic field generators 7A, 7B and 7C is generated in an arc shape in the horizontal direction only in the plane orthogonal to the extending direction of the conductive wire, unlike the case of the first embodiment. It exhibits a distribution that

Given the above, a method of finding the center of the Hall element for each probe will be described below.

(1) In the case of x probe First, the Hall element in the probe that crosses the first magnetic field generating portion 7A is the magnetic force of the xy plane in the first magnetic field generating portion, and is arcuate in the left-right direction. It will cut off the generated magnetic force.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, there is no magnetic force that passes through the main surface of the Hall element orthogonally, and therefore the output from the Hall element becomes zero.

That is, at this point, the center of the Hall element in the x-axis direction is known.

Then, the Hall element in the probe which crosses the second magnetic field generating section 7B is the magnetic force of the xy plane in the second magnetic field generating section 7B, which is a magnetic force generated in an arc shape in the left-right direction. Will be cut.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element orthogonally becomes the maximum, and therefore the output from the Hall element becomes the maximum.

That is, at this point, the center of the Hall element in the y-axis direction is known.

Further, the Hall element in the probe which traverses the third magnetic field generating section 7C is to cut off the magnetic force generated in the vertical direction by the magnetic force of the xz plane in the third magnetic field generating section 7C. become.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element orthogonally becomes the maximum, and therefore the output from the Hall element becomes the maximum.

That is, at this point, the center of the Hall element in the z-axis direction is known.

(2) In case of y-probe First, the Hall element in the probe which crosses the first magnetic field generating section 7A is the magnetic force on the xy plane in the first magnetic field generating section 7A, and has an arc shape in the left-right direction. It will cut off the magnetic force generated in.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, there is no magnetic force that passes through the main surface of the Hall element orthogonally, and therefore the output from the Hall element becomes zero.

That is, at this point, the center of the Hall element in the x-axis direction is known.

Then, the Hall element in the probe which crosses the second magnetic field generating section 7B is the magnetic force of the xy plane in the second magnetic field generating section 7B, which is a magnetic force generated in an arc shape in the left-right direction. Will be cut.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element orthogonally becomes the maximum, and therefore the output from the Hall element becomes the maximum.

That is, at this point, the center of the Hall element in the y-axis direction is known.

Further, the Hall element in the probe which crosses the third magnetic field generating section 7C is designed to cut off the magnetic force generated in the xz plane in the third magnetic field generating section 7C and which is generated in an arc shape in the left-right direction. become.

Therefore, at the boundaries of the magnetic forces generated in the respective directions, the magnetic force that passes through the main surface of the Hall element orthogonally becomes the maximum, and therefore the output from the Hall element becomes the maximum.

That is, at this point, the center of the Hall element in the z-axis direction is known.

In this case, the center of the Hall element in the z-probe cannot be detected because the main surface of the Hall element is a plane with a different magnetic field distribution in the magnetic field generating portion, as shown in the relationship with other probes in FIG. This is because they will match. This is different from the fact that the magnetic field generators (electromagnetic coils 3A, 3B, 3C, and 3D) shown in FIG. 1 have spatially different magnetic field distributions not limited to one plane.

As is clear from each of the embodiments described above, the Hall element is finely moved within the magnetic field having a different distribution by the magnetic field generating unit so as to traverse the magnetic field, and an output corresponding to the distribution of the magnetic field is constantly generated. It becomes possible to determine the current arrangement position of the Hall element (with respect to the probe serving as its support) by measuring and changing the output.

Here, the position of the Hall element is, for example,
This distance corresponds to the distance from the reference position, and this distance is stored as information, and is used later when configuring the position of the Hall element with respect to the probe.

[0090]

As is apparent from the above description,
According to the sensor mounting calibration device of the magnetic measurement device of the present invention, the center of the Hall element mounted on the probe can be accurately detected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a sensor mounting calibration device of a magnetic measurement device according to the present invention.

FIG. 2 is an explanatory view showing various probes measured by the sensor mounting calibration device of the magnetic measurement device according to the present invention.

FIG. 3 is an explanatory view explaining how to use the sensor mounting calibration device of the magnetic measurement device according to the present invention.

FIG. 4 is a schematic configuration diagram showing another embodiment of the sensor attachment calibration device of the magnetic measurement device according to the present invention.

FIG. 5 is an explanatory view showing the reason why the z probe cannot be measured in another embodiment of the sensor attachment calibration device of the magnetic measurement device according to the present invention.

[Explanation of symbols] 1 ... shield, 2 ... yoke, 3A, 3B, 3C, 3
D ... Electromagnetic coil, 4 ... Probe, 6x, 6y, 6z
……Hall element.

Claims (4)

[Claims] 1. A device for calibrating a sensor of a magnetic measuring device comprising a hall element for measuring the strength of a magnetic field in the x direction, the center of the hall element being detected, the device being calibrated in a magnetically shielded space. , As a means for determining the center in the x direction, at least xy
A magnetic field generating section for generating a magnetic field in the horizontal direction with a distribution in the left-right direction, a moving unit for finely moving the Hall element in the x direction across the distribution of the magnetic field, and a movement of the Hall element by this moving unit. A detection means for detecting the time when the output becomes 0 in the process, and as a means for defining the center in the y direction, at least a magnetic field generating portion for generating a magnetic field in the left-right direction on the xy plane, and a distribution of the magnetic field A moving means for finely moving the hall element in the y direction so as to traverse the hall element, and a detecting means for detecting a time point when the output in the movement process of the hall element reaches a maximum value by the moving means. As a means for determining, the magnetic field generating portion for generating a magnetic field in the left-right direction at least in the xz plane, and the Hall element in the z direction so as to cross the distribution of the magnetic field. Bido moving means for moving the sensor mounting calibration apparatus of a magnetic measurement device output in moving process of the Hall element by the moving means and having a detecting means for detecting a time when the maximum value. 2. A device for calibrating a sensor of a magnetic measuring device for detecting the center of the Hall element of a magnetic measuring device comprising a Hall element for measuring the strength of a magnetic field in the y direction, wherein the apparatus is provided in a magnetically shielded space. , As a means for determining the center in the x direction, at least xy
A magnetic field generating section for generating a magnetic field in the horizontal direction with a distribution in the left-right direction, a moving unit for finely moving the Hall element in the x direction across the distribution of the magnetic field, and a movement of the Hall element by this moving unit. A detection means for detecting a time point at which the output in the process reaches a maximum value, and as a means for defining the center in the y direction, a magnetic field generating portion for generating a magnetic field with a lateral distribution at least in the xy plane, It has a moving means for finely moving the hall element in the y direction across the distribution, and a detecting means for detecting the time when the output in the moving process of the hall element by the moving means becomes 0, and the center in the z direction. As a means for determining, the magnetic field generating portion for generating a magnetic field in the left-right direction at least in the xz plane, and the Hall element in the z direction so as to cross the distribution of the magnetic field. Bido moving means for moving the sensor mounting calibration apparatus of a magnetic measurement device output in moving process of the Hall element by the moving means and having a detecting means for detecting a time when the maximum value. 3. A device for calibrating a sensor of a magnetic measuring device, which detects the center of the Hall element of a magnetic measuring device comprising a Hall element for measuring the strength of a magnetic field in the z direction, in a magnetically shielded space. , As a means for determining the center in the x direction, at least xy
A magnetic field generating section for generating a magnetic field in the horizontal direction with a distribution in the left-right direction, a moving unit for finely moving the Hall element in the x direction across the distribution of the magnetic field, and a movement of the Hall element by this moving unit. A detection means for detecting a time point at which the output in the process reaches a maximum value, and as a means for defining the center in the y direction, a magnetic field generating portion for generating a magnetic field with a lateral distribution at least in the xy plane, It has a moving means for finely moving the hall element in the y direction across the distribution, and a detecting means for detecting the time when the output of the hall element in the moving process of the hall means reaches a maximum value. As means for determining the center, at least an xz plane is used to generate a magnetic field in the left-right direction by generating a magnetic field generating portion and the Hall element so as to cross the magnetic field distribution. Moving means for Bido moved in direction, the sensor mounting calibration apparatus of a magnetic measurement device output in moving process of the Hall element by the moving means and having a detecting means for detecting a time when the 0. 4. A magnetic field space in which one pole is opposed on the x-axis and the other pole is opposed on the y-axis is formed in the space where the geomagnetism is shielded, and in the magnetic field space,
A Hall element for measuring the strength of a magnetic field in any of the x, y, and z directions is made to face one pole on the y axis and moved in the x direction, and then made to face one pole on the x axis. Moving means for moving in the y direction and then in the z direction facing one of the poles on the x axis, and a time point when the output in the moving process of the Hall element by this moving means becomes 0 or the maximum value. 5. A sensor mounting calibration device for a magnetic measuring device, characterized in that it is provided with a detecting means for detecting.