JP2020118503A - Linear gauge - Google Patents

Abstract

To provide a linear gauge for moving a shaft up and down while being contactlessly supported and measuring the top face height of a measurement object, with which, while allowing air exhaust for an air bearing, the shaft is prevented from becoming unable to move vertically due to the grinding dust stuck to the side surface of the shaft.SOLUTION: Provided is a linear gauge 4 comprising: a shaft 40 provided with a probe 400 at the tip; a casing 41 having a support surface for enclosing and supporting the side surface of the shaft; an air ejection opening 42 disposed on the support surface, with air interposed between the side surface of the shaft and the support surface; an exhaust opening 43 disposed below the casing 41 and formed in a ring shape enclosing the side surface of the shaft, for guiding the air ejected from the air ejection opening 42 toward a measurement object along the side surface of the shaft and having it discharged; and means 44 for enclosing the exhaust opening 43 and forming a water screen on the side surface of the shaft. While allowing air exhaust from the exhaust opening 43, extraneous matter is prevented from sticking to the shaft 40 and the probe 400 by the water screen formed by the water screen forming means 44.SELECTED DRAWING: Figure 2

Description

The present invention relates to a linear gauge that measures surface displacement of an object to be measured.

As disclosed in Patent Document 1, a grinding apparatus for grinding a work piece held on a chuck table to a predetermined thickness with a grinding wheel while supplying grinding water is held by a chuck table holding a work piece. The height of the surface and the height of the upper surface of the workpiece held by the holding surface are measured, and the height difference is calculated as the thickness of the workpiece.

Further, in measuring the height of each surface as described above, a linear gauge is used, a shaft equipped with a probe at the tip is moved vertically in a straight line, and the height position of the shaft is detected by a detector to achieve high accuracy. Height measurement is possible (for example, refer to Patent Document 2).

JP, 2008-073785, A JP, 2005-175758, A

The linear gauge as described above is provided with an air bearing for ejecting air toward the side surface of the shaft and supporting the shaft in a non-contact manner so as not to apply a load to the vertical movement of the shaft. The air used for this air bearing is exhausted toward the workpiece along the side surface of the shaft, so that grinding dust is generated in the grinding chamber by performing grinding while supplying grinding water. Prevents the grinding spray from entering the linear gauge.

However, there is a problem that a vortex is generated around the shaft due to the exhaust of the air, the grinding spray is dried, the grinding dust contained in the grinding spray is fixed to the shaft, and the shaft cannot move up and down.
Therefore, in a linear gauge that measures the height of the upper surface of the object to be measured by directly moving the shaft in the vertical direction while supporting the shaft in a non-contact manner with the air bearing, it is possible to exhaust the air from the air bearing and There is a problem of preventing the shaft from moving up and down due to the adhered grinding dust.

The present invention for solving the above-mentioned problems is a linear gauge for measuring the surface displacement of an object to be measured, the shaft having a tip with a probe contacting the surface of the object to be measured, and a side surface of the shaft. A casing having a supporting surface for supporting the same, an air ejection port arranged on the supporting surface for interposing air between the side surface of the shaft and the supporting surface, and a casing arranged under the casing for the shaft. An exhaust port formed in a ring shape surrounding the side surface for exhausting the air ejected from the air ejection port toward the object to be measured along the side surface of the shaft, and a water film surrounding the exhaust port on the side surface of the shaft. And a water film forming means for forming air to enable air to be exhausted from the exhaust port, and prevent a deposit from adhering to the shaft and the probe due to the water film formed by the water film forming means. It is a linear gauge that protects.

It is preferable that the water film forming means includes a water supply nozzle including an annular water ejection port that surrounds the exhaust port.

The water film forming means includes an annular pipe that surrounds the shaft, a supply unit that supplies water to the annular pipe from one position of the annular pipe, and a symmetry at the one position with respect to the center of the annular pipe. A water jet outlet for jetting water toward the object to be measured at the other opposite position, and the axis of the shaft generated when the water supplied from the supply unit to the annular pipe flows through the annular pipe. It is preferable that the force in the circumferential direction centering on the axis remains when water merges at the water ejection port, so that the water covers the side surface of the shaft and flows toward the object to be measured to form the water film.

A linear gauge for measuring the surface displacement of an object to be measured according to the present invention includes a shaft having a probe at the tip for contacting the surface of the object to be measured, and a casing having a supporting surface surrounding and supporting a side surface of the shaft. , An air ejection port which is arranged on the support surface and has air interposed between the side surface of the shaft and the support surface, and a ring shape which is arranged below the casing and surrounds the side surface of the shaft and ejected from the air ejection port Since the exhaust port for exhausting air toward the object to be measured along the side surface of the shaft and the water film forming means surrounding the exhaust port to form a water film on the side surface of the shaft are provided, the air is exhausted from the exhaust port. It becomes possible to exhaust the water and the water film formed by the water film forming means can protect the shaft and the tracing stylus from the attachment of grinding dust and the like. Further, the air exhausted from the exhaust port and the water supplied from the water film forming means remove grinding debris from the surface of the measured object with which the contact point comes into contact, so that the measurement error of the displacement of the surface of the measured object is reduced. It can be prevented from occurring.

In the linear gauge according to the present invention, the water film forming means includes the water supply nozzle having the annular water jet port that surrounds the exhaust port, so that the water film can be easily formed.

In the linear gauge according to the present invention, the water film forming means includes an annular pipe that surrounds the shaft, a supply unit that supplies water from one position of the annular pipe, and a symmetrical position at one position with respect to the center of the annular pipe. By providing a water ejection port which is formed on the opposite side of the supply unit at the other position and ejects water toward the object to be measured, the water supplied from the supply unit to the annular pipe flows through the annular pipe. The generated circumferential force around the shaft axis remains when the water merges at the water outlet, allowing the water to cover the side surface of the shaft and flow toward the DUT, facilitating the water film. Can be formed.

It is a perspective view which shows an example of a linear gauge. It is sectional drawing which shows an example of a linear gauge. It is sectional drawing for demonstrating an example of a water film forming means. It is sectional drawing for demonstrating another example of a water film forming means.

The linear gauge 4 according to the present invention shown in FIG. 1 is disposed in, for example, a grinding device (not shown) for grinding a workpiece such as a semiconductor wafer, and the surface displacement of the semiconductor wafer or the like as the workpiece W, that is, It is possible to measure the height position of the surface Wa of the object to be measured W, which changes with time due to the grinding process or the like.

The linear gauge 4 shown in FIGS. 1 and 2 surrounds and supports, for example, a direct-acting type shaft 40 having a tip 400 of a tracing stylus 400 that contacts the surface Wa of the object to be measured W and a side surface 40a of the shaft 40. A casing 41 having a support surface 41a, an air ejection port 42 disposed on the support surface 41a for interposing air between a side surface 40a of the shaft 40 and the support surface 41a, and a shaft 40 disposed below the casing 41. An exhaust port 43, which is formed in a ring shape and surrounds the side surface 40a, exhausts the air ejected from the air ejection port 42 toward the object W along the side surface 40a of the shaft 40, and the exhaust port 43 of the shaft 40 surrounding the exhaust port 43. A water film forming means 44 for forming a water film on the side surface 40a.

The shaft 40 has, for example, a cylindrical outer shape, and the tracing stylus 400 is detachably connected to the lower end side thereof. The lower end 400c of the tracing stylus 400 according to the present embodiment is formed of diamond or the like into a rounded spherical surface.

As shown in FIG. 1, the upper end side of the shaft 40 extending in the vertical direction (Z-axis direction) is connected to the lower surface side of a fixed plate 490 having a rectangular flat plate shape by a fixing nut 491, for example.
The linear gauge 4 has a flat plate-shaped support plate 480 that faces the fixed plate 490 in the Z-axis direction and is parallel to the fixed plate 490. As shown in FIG. 2, the shaft 40 penetrates the circular hole 480 a of the support plate 480, and the tracing stylus 400 connected to the lower end side of the shaft 40 and the lower end side of the shaft 40 is provided from the lower surface of the support plate 480. It projects downward.

The linear gauge 4 includes, for example, a rotation restricting unit 50 that restricts the rotation of the shaft 40 supported by the casing 41 in a non-contact manner around the axis (Z-axis direction) of the shaft. The rotation restricting means 50 directs a magnetic field in a direction that repels the magnetic field of the first magnet 501 and the first magnet 501 having a block shape, and the first magnet 501 is sandwiched between the first magnet 501 and the first magnet 501. By at least two second magnets 502 extending in the Z-axis direction parallel to the axial direction of 40, and a guide rod 503 that is connected to the first magnet 501 and moves the first magnet 501 in the Z-axis direction. It is configured.

The upper end side of the guide rod 503 is connected to the fixed plate 490 and extends parallel to the extending direction of the shaft 40. A first magnet 501 is fixed to the lower end side of the guide rod 503. The two second magnets 502 are fixed to the side surface of the casing 41 with the first magnet 501 interposed therebetween. Then, the first magnet 501 and the second magnet 502 repel each other, so that the horizontal distance between the second magnet 502 and the guide rod 503 is kept constant, and the direction of the guide rod 503 changes. Never. Therefore, since the guide rod 503 whose orientation is invariable is connected to the shaft 40 via the fixing plate 490, even if the shaft 40 is formed in a cylindrical shape, the rotation restricting means 50 prevents the shaft 40 from moving in the rotation direction. Can be regulated.
The shape of the shaft 40 is not limited to the cylindrical shape, and may be a non-rotating shape, that is, a non-cylindrical shape. Therefore, it may be a polygonal prism or an elliptic cylinder. Further, it may be a columnar shape in which only one surface is formed as a flat surface and the other surface is formed as a curved surface. Corresponding to this, the support surface 41a of the casing 41 may be formed to match the shape of the shaft 40. In this case, the rotation restricting means 50 may not be included in the linear gauge 4.

The casing 41 has, for example, a rectangular parallelepiped frame body 410 arranged on the upper surface of the support plate 480, and the shaft 40 can be inserted into the frame body 410 to support the side surface 40a of the shaft 40 in a non-contact manner. It is composed. The shaft 40 is formed in a columnar shape in the present embodiment, and correspondingly, the frame body 410 is formed with an accommodation hole 41 d having a circular cross section for accommodating the shaft 40.
The frame body 410 includes a support surface 41a that surrounds the side surface 40a and is spaced apart from the side surface 40a of the shaft 40 by an even gap, and an air that surrounds the side surface 40a of the shaft 40 and supports the side surface 40a of the shaft 40. On the other hand, a plurality of air ejection ports 42 ejected from the support surface 41a, an air inflow port 410c connected to an air supply source 60 such as a compressor, and a flow path communicating the air inflow port 410c with each air ejection port 42. And 410d.

One end of an air supply pipe 600 such as a metal pipe or a flexible resin tube communicates with the air inlet 410c via a joint 410e, and the air supply source 60 is connected to the other end of the air supply pipe 600. Are connected.

In the casing 41 configured in this way, the air supplied from the air supply source 60 to the air supply pipe 600 is ejected from each air ejection port 42 in a direction perpendicular to the side surface 40a of the shaft 40, whereby the shaft 40 can be supported in a non-contact state by being surrounded by air with a gap.

On the support plate 480, the linear drive means 20 for linearly moving the shaft 40 in the Z-axis direction is arranged. As shown in FIGS. 1 and 2, the linear drive means 20 is, for example, a piston cylinder, has a piston 200 inside, and has a bottom on the base end side (−Z direction side) and a cylinder tube 201. And a lower end of the piston rod 202 attached to the piston 200, and air inlets 203a and 203b for injecting air into the cylinder tube 201. The upper end side of the piston rod 202 can contact the lower surface of the fixed plate 490, and the proximal end side of the cylinder tube 201 is fixed to the upper surface of the support plate 480.

Air flow paths 204a and 204b are connected to the air inlets 203a and 203b, respectively, and the air flow paths 204a and 204b are selectively connected to the air supply source 60 via a solenoid valve 603, for example.

When the shaft 40 is lifted by the linear drive means 20 in the direction away from the surface Wa of the object to be measured W, the solenoid valve 603 is energized to bring the air supply source 60 into communication with the air flow path 204b. The air supplied from the supply source 60 flows into the air inlet 203b. Then, by supplying air into the cylinder tube 201 from below, the piston 200 is raised inside the cylinder tube 201. Then, the piston rod 202 is brought into contact with the lower surface of the fixed plate 490, and then the piston rod 202 is further raised to raise the fixed plate 490, thereby raising the shaft 40 connected to the fixed plate 490.

On the other hand, when the shaft 40 is lowered by the linear drive means 20 in the direction of approaching the surface Wa of the object to be measured W, the solenoid valve 603 is energized to bring the air supply source 60 into communication with the air flow path 204a. The air supply source 60 causes a predetermined air to flow into the air inlet 203a to supply the air into the cylinder tube 201 from above, and causes a predetermined air to flow out from the air inlet 203b. As a result, the piston rod 202 descends at a regulated speed while the upper end of the piston rod 202 is in contact with the lower surface of the fixed plate 490, so that the weight of the shaft 40 and the fixed plate 490 coupled to the shaft 40 is reduced. The speed at which the shaft 40 descends is limited. Then, the shaft 40 is lowered until the lower end 400c of the tracing stylus 400 contacts the surface Wa of the object W to be measured.

As shown in FIGS. 1 and 2, the height position reading means 25 is arranged at one corner of the lower surface of the fixed plate 490. The height position reading means 25 has its upper end fixed to the lower surface of the fixed plate 490, and the scale 250 extending in the −Z direction parallel to the extending direction (Z axis direction) of the shaft 40, and the scale 250. The reading unit 251 for reading the scale 250a and the supporting column 252 to which the reading unit 251 is fixed are provided. The support column 252 is fixed to the side surface of the support plate 480 and extends in the +Z direction. The reading unit 251 is fixed to the side surface of the support column 252, and faces the scale 250a formed on the side surface of the scale 250 at equal intervals in the Z-axis direction. The reading unit 251 is, for example, an optical type that reads the reflected light of the scale 250a of the scale 250, and converts the read value of the scale 250a of the scale 250 into the height position of the lower end 400c of the tracing stylus 400 of the shaft 40. The height position of the surface Wa of the object to be measured W can be read by performing the measurement.

As shown in FIGS. 2 and 3, a water supply nozzle 441 having, for example, a substantially cylindrical outer shape is detachably attached to the lower surface of the support plate 480 by a screw portion 441a formed on the upper portion thereof. A through hole 441b having a circular cross section for penetrating the shaft 40 in the thickness direction (Z-axis direction) is formed in the center of the water supply nozzle 441, and the lower end side of the through hole 441b is below the casing 41. The exhaust port 43 is formed in a ring shape and surrounds the side surface 40a of the shaft 40 to exhaust the air ejected from the air ejection port 42 toward the object to be measured W along the side surface 40a of the shaft 40.
The through hole 441b, the circular hole 480a of the support plate 480, and the circular accommodating hole 41d of the casing 41 have centers substantially aligned with each other, and in the present embodiment, for example, have the same diameter.

The water film forming means 44 shown in FIGS. 2 and 3 (hereinafter, referred to as the water film forming means 44 of the first embodiment) includes the water supply nozzle 441 having an annular water ejection port 441c surrounding the exhaust port 43. ing.
For example, a water supply port 441d is formed on the side surface of the water supply nozzle 441, and the water supply port 441d communicates with the water ejection port 441c inside the water supply nozzle 441. In the example shown in FIGS. 2 and 3, the water jet port 441c is formed in a tubular shape whose diameter is reduced toward the lower end side of the water feed nozzle 441, and the water that has moved from the water feed port 441d to the water jet port 441c is The water supply nozzle 441 descends while flowing toward the center of the water supply nozzle 441, but is not limited to this.

One end of a water supply pipe 460 is connected to the water supply port 441d, and a water supply source 461 configured by a pump or the like and capable of supplying water (for example, pure water) is connected to the other end side of the water supply pipe 460. It is in communication.

The operation of the linear gauge 4 when the displacement of the surface Wa of the object W is measured by the linear gauge 4 will be described below with reference to FIGS. 2 and 3.
2 and 3, the object to be measured W is suction-held on a chuck table 10 (not shown in FIG. 3) of a grinding device (not shown), and is thinned by a grinding wheel that rotates while being supplied with grinding water. There is. That is, the object to be measured W is suction-held on the holding surface 10a, which is in communication with a suction source (not shown) of the chuck table 10 and is made of a porous member or the like, with the front surface Wa facing upward. It is rotating around the axial center.

As shown in FIG. 2, the linear gauge 4 is mounted on the support base 11 and is positioned above the object W to be measured. During the grinding of the object to be measured W, the displacement of the surface Wa of the object to be measured W is measured by using the linear gauge 4 to monitor the change in the thickness of the object to be measured W.
The linear drive means 20 lowers the shaft 40 in the −Z direction which approaches the object W to be measured. Specifically, the air supply source 60 shown in FIG. 2 causes a predetermined amount of air to flow into the air inlet 203a to supply the air into the cylinder tube 201, so that the inside of the cylinder tube 201 is controlled at a regulated speed. The piston 200 is moved downward (-Z direction). As a result, the shaft 40 is lowered until the lower end 400c of the tracing stylus 400 contacts the surface Wa of the object to be measured W while limiting the descending speed of the fixed plate 490 and the shaft 40 due to its own weight. In this way, since the linear motion drive means 20 limits the descending speed of the fixed plate 490 and the shaft 40, the impact when the lower end 400c of the tracing stylus 400 contacts the object W to be measured can be reduced.

At this time, the air is supplied from the air supply source 60 to the air inlet 410c, and the air is ejected from the air ejection port 42 between the side surface 40a of the shaft 40 and the support surface 41a of the casing 41 to interpose the casing 41. The shaft 40 can be vertically lowered in the Z-axis direction while supporting the side surface 40a of the shaft 40 in a non-contact manner.

When the tracing stylus 400 comes into contact with the surface Wa of the object to be measured W due to the lowering of the shaft 40, the reading unit 251 reads the scale 250a of the scale 250 when the lower end 400c of the tracing stylus 400 comes into contact with the surface Wa of the object to be measured W. ..
After that, the amount of air supplied from the air supply source 60 to the air inflow port 203a is adjusted, and the shaft 40 freely changes according to the change in the thickness of the measured object W, in other words, the displacement of the surface Wa of the measured object W. The linear gauge 4 can sequentially measure the displacement of the front surface Wa of the object to be measured W by sequentially reading the graduations 250a that the reading unit 251 changes.

While the displacement of the surface Wa of the measured object W is being measured by the linear gauge 4, the air supplied from the air ejection port 42 between the side surface 40a of the shaft 40 and the support surface 41a of the casing 41 is 40 descends in the accommodation hole 41d of the casing 41 along the side surface 40a of the casing 40, and further passes through the circular hole 480a of the support plate 480 to reach the water supply nozzle 441.
The air descends in the through hole 441b along the side surface 40a of the shaft 40 also in the water supply nozzle 441 and is exhausted from the annular exhaust port 43 toward the measured object W.

While the displacement of the surface Wa of the object to be measured W is being measured by the linear gauge 4, water is supplied from the water supply source 461 and the water flows into the water supply nozzle 441 from the water supply port 441d. .. Then, the water is ejected from the annular water ejection port 441c surrounding the exhaust port 43 toward the side surface 40a of the shaft 40 and flows downward toward the object W to be measured while covering the side surface 40a of the shaft 40 as a water film. Go As a result, air is exhausted from the exhaust port 43, and the water film formed by the water film forming means 44 protects the shaft 40 and the tracing stylus 400 from deposits. That is, even if the grinding spray containing grinding dust is flying around the shaft 40 and the tracing stylus 400 protruding downward from the water supply nozzle 441, the water film prevents contact with the side surface 40a of the shaft 40 and the tracing stylus 400. It also prevents peeling and sticking due to drying.

The linear gauge 4 for measuring the surface displacement of the object to be measured W according to the present invention surrounds a shaft 40 having a tip 400 of a tracing stylus 400 that contacts the surface Wa of the object to be measured W and a side surface 40a of the shaft 40. A casing 41 having a supporting surface 41a for supporting, an air ejection port 42 arranged on the supporting surface 41a for interposing air between the side surface 40a of the shaft 40 and the supporting surface 41a, and a shaft arranged under the casing 41. An exhaust port 43 that is formed in a ring shape surrounding the side surface 40a of the exhaust port 40 and that exhausts air ejected from the air ejection port 42 toward the object W along the side surface 40a of the shaft 40 and a shaft that surrounds the exhaust port 43. Since the water film forming means 44 for forming a water film is provided on the side surface 40a of the shaft 40, air can be exhausted from the exhaust port 43, and the shaft 40 is formed by the water film formed by the water film forming means 44. Further, it is possible to protect the tracing stylus 400 from being attached with an adhering material such as grinding dust. Further, the air exhausted from the exhaust port 43 and the water supplied from the water film forming means 44 remove the grinding dust from the surface Wa of the measured object W with which the tracing stylus 400 comes into contact, as shown in FIG. Since it flows over the surface Wa of the object to be measured W, it is possible to prevent the measurement error of the displacement of the surface Wa of the object to be measured W by the linear gauge 4 from occurring.

In the linear gauge 4 according to the present invention, the water film forming means 44 is provided with the water supply nozzle 441 having the annular water ejection port 441c surrounding the exhaust port 43, so that the water film can be easily formed. Is possible.

The linear gauge 4 according to the present invention may include a water film forming means 45 shown in FIG. 4 instead of the water film forming means 44 shown in FIGS.
The water film forming means 45 includes an annular pipe 450 surrounding the shaft 40, a supply unit 451 for supplying water from one position 450a (a position on the +X direction side in FIG. 4) of the annular pipe 450, and an annular pipe 450. Water that is formed on the opposite side of the supply unit 451 at the other position 450b (position on the −X direction side in FIG. 4) symmetrical to the one position 450a with respect to the center and ejects water toward the measured object W. And a jet port 452. In the present embodiment, the above-mentioned respective constituent elements of the water film forming means 45 are arranged, for example, in a substantially columnar columnar body 459 attached to the lower surface of the support plate 480.

A threaded portion 459a is formed on the upper surface of the pillar 459, and the pillar 459 is detachably attached to the lower surface of the support plate 480 by the threaded portion 459a. A through hole 459b having a circular cross section for penetrating the shaft 40 in the thickness direction (Z-axis direction) is formed in the center of the columnar body 459. The through hole 459b is, for example, a circular hole 480a of the support plate 480. The diameters are substantially the same, and the center of the circular hole 480a is aligned with the center of the circular hole 480a.

The lower end side of the through hole 459b is formed under the casing 41 and is formed in a ring shape surrounding the side surface 40a of the shaft 40, and the air ejected from the air ejection port 42 is directed to the measured object W along the side surface 40a of the shaft 40. It becomes the exhaust port 43 for exhausting toward. In the example shown in FIG. 4, the exhaust port 43 has a diameter larger than that of the through hole 459b, but is not limited to this.

The supply part 451 is formed, for example, so as to extend horizontally from the side surface of the columnar body 459 to the inside of the columnar body 459 and then further downward, and at one position 450a of the annular pipe 450 inside the columnar body 459. It is in communication. One end of the water supply pipe 460 is connected to the supply unit 451, and the other end side of the water supply pipe 460 is connected to a water supply source 461 that is configured by a pump or the like and can supply water (for example, pure water). doing.
The water ejection port 452 extends, for example, in a straight line from the other position 450b of the annular pipe 450 toward the center of the columnar body 459, and communicates with the exhaust port 43.

While the displacement of the surface Wa of the object to be measured W is being measured by the linear gauge 4 including the water film forming means 45, the side surface 40a of the shaft 40 and the supporting surface of the casing 41 from the air ejection port 42 shown in FIG. The air supplied between the column 41a and the side 41a descends in the accommodation hole 41d of the casing 41 along the side surface 40a of the shaft 40, further passes through the circular hole 480a of the support plate 480, and the column shown in FIG. Reach body 459.
The air descends in the through hole 459b along the side surface 40a of the shaft 40 in the column body 459, and is exhausted from the exhaust port 43 toward the measured object W.

During measurement of the displacement of the surface Wa of the object W by the linear gauge 4 including the water film forming means 45 shown in FIG. 4, water is supplied from the water supply source 461 and the water is supplied from the supply unit 451. It flows into the columnar body 459. The water supplied from the supply part 451 to one position 450a of the annular pipe 450 is divided into two and flows in the annular pipe 450 in the clockwise direction and the counterclockwise direction as viewed from the +Z direction, respectively, and as a result, A circumferential force about the axis of the shaft 40 in the Z-axis direction is generated in each of the two divided waters.

Then, when the water flowing in the annular pipe 450 divided into the two hands reaches the water jet ports 452 and merges with each other, the circumferential force remains so that the water passes through the exhaust port 43 and passes through the shaft 40. The water that has moved to the side surface 40a becomes a water film having, for example, a spiral flow, covers the side surface 40a, and descends toward the object W to be measured. As a result, air is exhausted from the annular exhaust port 43, and the shaft 40 and the tracing stylus 400 are protected by the water film formed by the water film forming means 45 so that adhered substances do not adhere. That is, even if the grinding spray containing grinding dust is flying around the shaft 40 and the tracing stylus 400 protruding downward from the columnar body 459, the water film prevents contact with the side surface 40a of the shaft 40 and the tracing stylus 400. In addition, it is also possible to prevent the film from sticking due to drying.

As described above, in the linear gauge 4 according to the present invention, the water film forming means 45 includes the annular pipe 450 surrounding the shaft 40, the supply portion 451 that supplies water from one position 450a of the annular pipe 450, and the annular pipe 450. By providing a water jet port 452 which is formed on the opposite side of the supply unit 451 at the other position 450b symmetrical to the one position 450a with respect to the center of the pipe 450 and which jets water toward the DUT W. A circumferential force around the shaft center of the shaft 40, which is generated when the water supplied from the supply unit 451 to the annular pipe 450 flows through the annular pipe 450, remains when the water merges at the water ejection port 452. This allows water to cover the side surface 40a of the shaft 40 and flow toward the object W to be measured to easily form a water film.

It is needless to say that the linear gauge 4 according to the present invention is not limited to the example including the water film forming means 44 or the water film forming means 45 described above, and may be implemented in various different forms within the scope of the technical idea thereof. .. Further, the outer shape and the like of each component of the linear gauge 4 shown in the accompanying drawings is not limited to this, and can be appropriately changed within a range in which the effects of the present invention can be exhibited.

W: Object to be measured Wa: Surface of object to be measured 4: Linear gauge 40: Shaft 40a: Side surface of shaft 400: Measuring element 400c: Lower end 41 of measuring element 41: Casing 410: Frame 41d: Housing hole 41a: Support surface 410c : Air inlet 410d: Flow path 42: Air jet 43: Exhaust 44: Water film forming means
441: Water supply nozzle 441a: Screw part 441b: Through hole 441c: Water jet port 441d: Water supply port 46: Water supply source 460: Water supply pipe 490: Fixed plate 491: Fixed nut 480: Support plate 480a: Circular hole 50 : Rotation regulating means 501: First magnet 502: Second magnet 503: Guide rod 60: Air supply source 600: Air supply pipe 603: Solenoid valve
20: Linear drive means 200: Piston 201: Cylinder tube 202: Piston rod 203a, 203b: Air inlets 204a, 204b: Air flow path 25: Height position reading means 250: Scale 250a: Scale 251: Reading section 252: Support column 11: Support stand 10: Chuck table 10a: Holding surface 45: Water film forming means 450: Annular tube 451: Supply part 452: Water jet port 459: Column body

Claims (3)

A linear gauge for measuring the surface displacement of an object to be measured,
A shaft equipped with a probe that contacts the surface of the object to be measured,
A casing having a support surface surrounding and supporting the side surface of the shaft;
An air ejection port which is disposed on the support surface and has air interposed between the side surface of the shaft and the support surface;
An exhaust port which is formed under the casing and is formed in a ring shape surrounding the side surface of the shaft to exhaust the air ejected from the air ejection port toward the object to be measured along the side surface of the shaft;
A water film forming means surrounding the exhaust port and forming a water film on the side surface of the shaft,
A linear gauge that allows air to be exhausted from the exhaust port and protects the shaft and the probe from deposits by a water film formed by the water film forming means. The linear gauge according to claim 1, wherein the water film forming means includes a water supply nozzle including an annular water jet outlet that surrounds the exhaust port. The water film forming means,
An annular tube surrounding the shaft,
A supply unit for supplying water from one position of the annular pipe to the annular pipe,
A water jet outlet for jetting water toward the object to be measured at the other position symmetrical to the one position with respect to the center of the annular pipe,
A circumferential force around the shaft center of the shaft generated by the water supplied from the supply unit to the annular pipe flowing through the annular pipe remains when the water merges at the water ejection port. 2. The linear gauge according to claim 1, wherein water flows over the side surface of the shaft toward the object to be measured to form the water film.

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