JPH08210830A - Non-contact type length measuring device - Google Patents

Abstract

(57) [Summary] [Structure] A cylinder in which a piston is supported by static pressure, an injection nozzle provided in a rod of the piston, detection means for detecting a displacement amount of the piston, and a top and bottom formed by the piston 2
A non-contact type length measuring instrument comprising an adjusting means for adjusting the pressure of one of the first pressurizing chambers, the first piston connecting the tip of the rod and the side wall surface of the piston to the piston. And a second through hole connecting the tip of the rod and the second pressure chamber. [Effect] Since the high-pressure air pressure supplied to support the piston under static pressure can be directly ejected from the ejection nozzle, a length measuring instrument with high sensitivity can be obtained. Further, since the back pressure from the object to be measured is taken in through the second through hole formed in the piston or the rod, the back pressure does not fluctuate with the movement of the piston, and the variation in the measured value is reduced. can do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type length measuring device used for measuring the shape and size of an object to be measured, or flatness and straightness.

[0002]

2. Description of the Related Art Conventionally, a non-contact type length-measuring device (hereinafter referred to as a length-measuring device) used for measuring the shape and size of an object to be measured, or flatness and straightness is shown in FIGS. There was something like that shown in 8.

For example, a length measuring device 30 shown in FIG. 8 has a cylinder type structure, and a cylinder 34 is formed by a sealing member 33 such as an O-ring provided on the outer wall surface of a piston 31.
Is divided into two pressure chambers, and the lower pressure chamber 37 is connected to the piston 31.
Injection nozzle 3 attached to the tip of rod 32 protruding further
5 is communicated with the inner hole 35a of the injection nozzle 35 through the tube 39, and air is supplied to the outer hole 35b of the injection nozzle 35, which is separately provided, so that the object to be measured 5 is supplied from the tip of the injection nozzle 35
It is designed to jet toward 0. Further, a stylus portion 36a of the electric micrometer 36 is provided at the rear end of the rod 32.
Is fixed to the cylinder 34 so as to come into contact with the end surface of the rod 32, and the displacement amount of the piston 31 is detected.

In order to carry out the measurement with the length measuring device 30, first, a pressure serving as a reference pressure is supplied to the upper pressurizing chamber 38 of the cylinder 34, and the outer hole 3 of the injection nozzle 35 is supplied.
When air is supplied to 5 b by injecting air to the object to be measured 50 from the injection nozzle 35, the back pressure is taken from the inner hole 35 a of the injection nozzle 35 into the lower pressurizing chamber 37 via the tube 39, so that the lower pressure is applied. Back pressure in pressure chamber 37 and upper pressure chamber 3
The piston 31 stops at a position where the reference pressure of 8 is balanced. At this time, since the injection nozzle 35 stands still while maintaining a constant distance from the object 50 to be measured, the value of the electric micrometer 36 at this time is detected as a reference value and the length measuring device 30 is moved left and right. Since the back pressure increases / decreases along the surface shape of the object 50 to be measured, the piston 31 moves up and down according to the change in the back pressure, and the displacement amount of the piston 31 is detected by the electric micrometer 36. As a result, the shape and size of the DUT 50, or the straightness and flatness can be measured in a non-contact state.

Further, the length measuring device 40 shown in FIG.
An actuator that statically supports 1 in the cylinder 44;
The air micro-type nozzle 45 is provided at the tip of the rod 42 projecting from the piston 41, and the differential pressure gauge 46 and the drive device 49 for moving the piston 41 by an electric signal from the differential pressure gauge 46 ( Actual Kaihei 4
-43210 gazette).

The length measuring device 40 is an upper chamber 4 of an air micro type nozzle 45 (hereinafter abbreviated as a nozzle) having a two-stage aperture.
The air supplied to 5b is supplied to the lower chamber 45a through the orifice 45c and jetted from the tip of the nozzle 45 to the DUT 50. The back pressure from the DUT 50 is taken into the lower chamber 45a. Then, the differential pressure gauge 46 is used to detect the differential pressure from the reference pressure, and the differential pressure is converted into an electric signal. Then, since the electric signal is applied to the moving coil 49a (hereinafter, simply referred to as a coil) forming the driving device 49, the coil 49 is generated by an electromagnetic force.
The nozzle 45, which is integrated with a, moves while being kept at a constant distance from the object 50 to be measured, and the displacement amount of the nozzle 45, that is, the surface of the object 50 to be measured, is monitored by monitoring the current flowing through the coil 49a. It was supposed to measure the condition.

[0007]

However, in the length measuring device 30 as shown in FIG. 8, since the sealing member 33 provided on the outer wall surface of the piston 31 is in pressure contact with the cylinder 34, the startability of the piston 31 is reduced. Poorly, since the sliding resistance is constantly generated during movement, the followability of the piston 31 was very poor. In addition, the frictional heat generated by the sliding resistance raises the temperature in the cylinder 34 and expands the air, which is the working medium, causing variations in the measured values, making it difficult to obtain a highly accurate length measuring instrument. there were. In addition, since the sealing member 33 is made of an elastic material such as rubber, it is worn out severely, and its characteristics are greatly deteriorated due to aging, so that the sealing member 33 must be replaced in a short period of time.

On the other hand, in the length measuring device 40 shown in FIG. 7, since the back pressure from the object 50 to be measured is very weak, the accuracy of the differential pressure gauge 46 at present cannot detect the differential pressure from the reference pressure. There is a possibility that a dead zone may occur, and it may be impossible to detect minute irregularities on the surface of the DUT 50.

The differential pressure detected by the differential pressure gauge 46 is converted into an electric signal and applied to the coil 49a, but the electric resistance of the coil 49a itself causes the coil 49a to generate heat and deform due to thermal expansion. Therefore, the magnetic flux density between the magnet 49b and the coil 49a changes, and the coil 49a
Since the linearity between the electric signal applied to and the movement amount of the piston 41 cannot be obtained, there is a possibility that the measured value may vary. Moreover, since the magnetic flux density changes due to the movement of the coil 49a, it is difficult to obtain the linearity between the electric signal applied to the coil 49a and the movement amount of the piston 41 at this point as well, and the differential pressure detected by the differential pressure gauge 46 can be obtained. Coil 49a
It takes time to apply the voltage to the piston 41 to move the piston 41, and there is a problem in responsiveness.

Moreover, since the magnet 49b must be arranged on the axis of the coil 49a with high positional accuracy, it is very difficult to mount the drive device 49.

Therefore, the present inventor has previously proposed a length measuring device 1 as shown in FIG. 6 as a solution to the above-mentioned problems (Japanese Patent Application No. 5-79777).

The length measuring device 1 is adapted to supply air from a supply hole 11 provided in a side wall of the cylinder 10 to support the piston 2 under static pressure, and also to a lower pressurizing chamber 7 partitioned by the piston 2. The leak pressure thus generated is injected from the injection nozzle 5 to the object 50 to be measured via the tube 15.
A pressure regulating valve 12 is arranged in the upper pressurizing chamber 8 partitioned by the piston 2 so that the pressure in the upper pressurizing chamber 8 is set to a constant pressure. Therefore, since the upper and lower pressurizing chambers 7 and 8 are in a kind of hermetically sealed state, when the object 50 to be measured is brought close to the injection nozzle 5, the back pressure rises, and the pressures in the pressurizing chambers 7 and 8 are equal. At this position, the piston 2 comes to rest, and the injection nozzle 5 is held with the object 50 to be measured kept at a constant distance. When the length measuring device 1 is moved on the object 50 to be measured, the back pressure changes in accordance with the change in the surface condition, so the piston 2 moves up and down according to the change amount, and the displacement amount of the piston 2 Is detected by the electric micrometer 14 to measure the surface state of the DUT 50.

In particular, since the length measuring device 1 is excellent in followability because the piston 2 is not in contact with the length measuring device 1, high precision measurement is possible.

However, in the length measuring device 1, the jet nozzle 5
Since the back pressure from is taken into the lower pressurizing chamber 7 via the tube 15, when the displacement amount of the piston 2 is large, the pressure inside the tube 15 fluctuates because the tube 15 bends. There is a problem in that the measurement accuracy may slightly vary. Moreover, since the injection nozzle 5 moves up and down, it is necessary to lengthen the tube 15 to some extent in order to prevent the tube 15 from bending, and there is a limit to downsizing the length measuring device 1.

Further, in the length measuring instrument 1, the leak pressure of the air supplied to support the piston 2 under static pressure is controlled by the lower pressurizing chamber 7.
Since it is designed to eject from the ejection nozzle 5 via the tube 15, it is difficult to obtain a large ejection pressure. Therefore, the back pressure caused by the fine irregularities on the surface of the object to be measured 50 cannot be detected, and the measurement with higher accuracy is difficult.

The object of the present invention is to improve the above-mentioned length measuring device 1 to increase the jet pressure from the jet nozzle 5 and to perform high-precision measurement without the back pressure being fluctuated by the bending of the tube 15. To provide a length measuring device 1.

[0017]

In view of the above problems, therefore, in the present invention, a piston is movably arranged in a cylinder, and an injection nozzle is provided at the tip of a rod projecting from the piston. Is a static pressure supporting means for supplying gas to a gap between the side wall surface of the piston, a detecting means for detecting a displacement amount of the piston, and a first pressurizing chamber of the two pressurizing chambers formed above and below by the piston. In a non-contact type length measuring instrument comprising pressure adjusting means for adjusting the pressure in the chamber, the piston has a first through hole connecting the tip of the rod and the side wall surface of the piston, and the tip of the rod. A second through hole connecting to the second pressurizing chamber is formed, gas is ejected from the injection nozzle toward the object to be measured, and the displacement of the piston according to the shape, size, surface condition, etc. of the object to be measured. Shape of the object to be measured by quantity Dimension, in which so as to measure the surface state and the like.

[0018]

According to the present invention, by providing the first through hole in the piston, the high-pressure air pressure supplied from the static pressure support means for statically supporting the piston can be directly ejected from the injection nozzle. Therefore, the ejection pressure from the ejection nozzle can be increased.

Therefore, the sensitivity of the length measuring instrument can be increased, and even minute irregularities on the object to be measured can be measured.

Further, according to the present invention, since the piston is provided with the second through hole to take in the back pressure from the object to be measured, the back pressure does not fluctuate due to the bending of the tube as in the conventional case. . Therefore, variations in measurement accuracy can be further reduced, and the length measuring device itself can be made compact.

[0021]

Embodiments of the present invention will be described below. The same parts as those in FIG. 6 are designated by the same reference numerals.

FIG. 1 is a perspective view in which a part of a non-contact type length measuring instrument 1 according to the present invention is cut away, and FIG. 2 is a sectional view taken along line XX of FIG. 1, in which an outer wall surface has a throttle groove 3. Supply hole 1 in which the piston 2 is loosely fitted in the cylinder 10 and provided on the side wall of the cylinder 10.
Cylinder 10 by supplying high air pressure from 1
An air layer is formed in the gap 13a between the piston 2 and the piston 2 to support the piston 2 under static pressure. Also, cylinder 1
An exhaust throttle valve 9 is provided on the upper part of 0 as a pressure adjusting means so that the pressure in the upper first pressurizing chamber 8 of the two pressurizing chambers formed by the piston 2 becomes substantially constant. It is set. That is, the pressure in the first pressurizing chamber 8 is determined by the effective sectional area of the throttle formed by the gap 13 a between the piston 2 and the cylinder 10 and the effective sectional area of the exhaust throttle valve 9. For example, the pressure from the supply hole 11 is P ₂ , the effective sectional area A _{1 of} the throttle formed by the gap 13 a between the piston 2 and the cylinder 10, and the exhaust throttle valve 9
Assuming that the effective sectional area is A ₂ , the pressure in the first pressurizing chamber 8 is P
₁ is represented by the following formula.

P ₁ = P ₂ / (A ₁ + A ₂ ) Then, since the effective sectional area A ₁ of the throttle formed by the gap 13a between the piston 2 and the cylinder 10 is basically constant, the exhaust throttle valve 9 By adjusting the effective sectional area A ₂ , that is, the throttle valve 9a of the exhaust throttle valve 9, the pressure in the first pressurizing chamber 8 can be set to a certain constant pressure.

Further, a linear scale 6a is provided on the side wall surface of the piston 2, and a scale head 6b for optically reading the value of the linear scale 6a of the piston 2 is provided on the side wall surface of the cylinder 10 to form the linear encoder 6. The displacement amount of the piston 2 is detected.

On the other hand, the piston 2 loosely fitted in the cylinder 10 is a prism 21 and the rod 4 is vertically projected from the center of the prism 21 toward the lower side.
An injection nozzle 5 having an inner hole 5a is attached to its tip.

The piston 2 (including the rod 4)
A double hole is formed inside the first through hole 2a. The first through hole 2a connects the tip of the rod 4 and the side wall surface of the piston 2, and a throttle portion 2c is provided at the tip. On the other hand, the second through hole 2b communicates with the second pressurizing chamber 7 through the tip of the rod 4 and the opening 2f formed at the base of the rod 4.

Therefore, a part of the high-pressure air pressure supplied from the supply hole 11 to the gap 13a between the cylinder 10 and the piston 2 is supplied to the first through hole 2a formed in the piston 2 and ejected from the injection nozzle 5. Can be made. Therefore, the ejection pressure from the ejection nozzle 5 can be increased and the sensitivity of the length measuring device 1 can be increased. Moreover, since the narrowed portion 2c is provided at the tip of the first through hole 2a, the high pressure air pressure supplied from the supply hole 11 is prevented from flowing into the second pressurizing chamber 7, and the inside of the cylinder 10 is prevented. The piston 2 can be supported by static pressure.

The back pressure from the object 50 to be measured is transmitted through the second through hole 2b formed in the piston 2 to the second pressure chamber 7
Therefore, the back pressure is not fluctuated as the piston 2 moves up and down. Therefore, it is possible to improve the responsiveness of the piston 2 with respect to the increase or decrease of the back pressure, and thus it is possible to further reduce the variation in the measured value.

A throttle 2d is also formed at the tip of the rod 4 of the second through hole 2b, and this throttle 2d can further suppress the pressure fluctuation of the back pressure which affects the measurement accuracy.

Further, on the side wall surface of the piston 2, a large number of vertical grooves 3a along the moving direction, a blast groove 3b communicating with the vertical groove 3a, and one lateral groove orthogonal to the vertical groove 3a. A throttle groove 3 made of 3c is formed. Therefore, since the air supplied from the supply hole 11 can be supplied to the entire gap 13a between the cylinder 10 and the piston 2, a uniform air layer can be formed in the gap 13a between the cylinder 10 and the piston 2. The piston 2 can be stably supported by static pressure.

However, in order to statically support the piston 2 in the cylinder 10, the width W of the gap 13a between the piston 2 and the cylinder 10 is 3 to 10 μm, preferably 3 to 4 μm.
It is important that

That is, when the width W of the gap 13a between the piston 2 and the cylinder 10 becomes smaller than 3 μm, the gap 13a is too narrow to form an air layer, and the piston 2 is supported by the static pressure in the cylinder 10. On the contrary, when the width W of the gap 13a is larger than 10 μm, a high-pressure air layer sufficient to support the piston 2 cannot be formed, and the piston 2 comes into contact with the side wall surface of the cylinder 10. This is because it will end up.

Next, the operating principle of the length measuring instrument 1 shown in FIGS.

First, when air is supplied from the supply hole 11 of the cylinder 10, a gap 13 between the piston 2 and the cylinder 10 is generated.
An air layer is formed in a, the piston 2 is statically supported in the cylinder 10, and a part of the piston 2 is formed in the first through hole 2a.
Then, the pressure is reduced by the narrowed portion 2c at the tip and ejected from the ejection nozzle 5 toward the DUT 50. At this time, in the present invention, since the first through hole 2a is formed in the piston 2,
Since the high-pressure air pressure supplied from the supply hole 11 can be directly supplied to the injection nozzle 5, the injection pressure from the injection nozzle 5 can be increased. In addition, the first through hole 2a
Since the narrowed portion 2c is provided at the tip of the supply hole 1,
It is possible to prevent all the air pressure supplied from No. 1 from flowing into the second pressurizing chamber 7 and stably support the piston 2 in the cylinder 10 under static pressure. At this time, a slight amount of air is discharged from the exhaust throttle valve 9 to the outside air.

Here, the object to be measured 5 is attached to the tip of the injection nozzle 5.
When 0 is approached, back pressure is taken into the second pressurizing chamber 7 from the inner hole 5a of the injection nozzle 5 through the second through hole 2b formed in the rod 4, so that the second pressurizing chamber 7 The piston 2 is pushed upward as the pressure rises. And
When the pressures of the first pressurizing chamber 8 and the second pressurizing chamber 7 reach an equilibrium state, the piston 2 stops and the injection nozzle 5 stands still while maintaining a constant distance from the object 50 to be measured. At this time, when adjusting the gap between the injection nozzle 5 and the DUT 50, the gap can be freely set by adjusting the exhaust amount by the throttle valve 9a of the exhaust throttle valve 9, and the value of the linear encoder 6 at this time The measurement preparation is completed by measuring with as a reference value.

Therefore, when the length measuring device 1 is moved left and right,
Since the back pressure changes along the surface shape of the DUT 50, the piston 2 of the length measuring device 1 moves up and down, and the linear displacement of the piston 2 is measured to measure the straightness of the DUT 50. The degree and flatness can be measured. This is because the inside of the cylinder 10 is in a kind of hermetically sealed state, and if there is a convex portion on the surface of the DUT 50, the back pressure increases, so the pressure in the second pressurizing chamber 7 increases, This is because the equilibrium state with the first pressurizing chamber 8 collapses and the piston 2 moves upward until it reaches the equilibrium state again. The displacement amount of the piston 2 at this time corresponds to the increase in the back pressure, and This corresponds to the height of the convex portion on the surface of 50.

On the other hand, if the surface of the object 50 to be measured has a concave portion, the back pressure is reduced, so that the equilibrium state with the pressure in the first pressurizing chamber 8 is disrupted, and the piston 2 is pushed down by the reduced back pressure. Since the injection nozzle 5 and the object to be measured 50 are always kept at a constant distance such that the piston 2
The movement displacement of the above indicates the surface state of the DUT 50 as it is.

Next, another length measuring device 1 according to the present invention is shown in FIG.

The length measuring instrument 1 shown in FIG. 3 has a first through hole 2a.
The shape of the through hole 2a is slightly changed, and the diameter of the through hole 2a is formed so as to become smaller as it goes to the tip end, thereby forming the aperture 2e at the tip of the first through hole 2a. Therefore, the high-pressure air pressure supplied from the supply hole 11 is reduced by the throttle 2e as in the length measuring device 1 of FIG.
The high-pressure air pressure supplied from the supply hole 11 is applied to the second pressure chamber 7
The piston 2 is prevented from flowing into the cylinder 10
Since the static pressure can be stably supported inside, and the high-pressure air pressure supplied from the supply hole 11 can be ejected from the ejection nozzle 5, the sensitivity of the length measuring instrument 1 can be enhanced.

Further, as another example of the present invention, the diaphragm portion 2c is removed from the length measuring instrument 1 shown in FIG.
The through hole 2a may have a smaller diameter. That is, since the first through hole 2a itself can be regarded as a narrowed portion by reducing the diameter of the first through hole 2a, by appropriately adjusting the diameter and length of the first through hole 2a, The piston 2 does not have to have the throttle portion 2c.
Can be stably supported by static pressure in the cylinder 10, and the high-pressure air pressure supplied from the supply hole 11 can be ejected from the ejection nozzle 5, so that the sensitivity of the length measuring instrument 1 can be enhanced.

Further, in the length measuring instrument 1 according to the present invention, the shape of the piston 2 is a prism 21. However, in the present invention, since the piston 2 is supported by static pressure, its shape is limited. However, if the inner shape of the cylinder 10 is made to match the outer shape of the piston 2, the outer shape of the piston 2 may be a columnar body, an elliptic cylinder, or a prism. Further, the throttle groove 3 formed on the side wall surface of the piston 2 is not limited to the throttle groove 3 shown in FIG. 2, and may have any shape as long as it can form an air layer uniformly over the entire circumference of the piston 2.

Further, the non-contact type length measuring device 1 shown in FIGS.
Although the embodiment in which the exhaust throttle valve 9 is arranged in the first pressurizing chamber 8 has been described above, the exhaust throttle valve 9 may be arranged in the second pressurizing chamber 7, and in this case, the second throttle valve formed on the piston 2 is used. One end of the through hole 2b may be extended to the upper end surface of the piston 2.

Further, in the non-contact type length measuring instrument 1 shown in FIGS. 1 and 2, the exhaust throttle valve 9 is used as the adjusting means for setting the pressure of the first pressurizing chamber 8 to a constant pressure. It may be a pressure regulating valve used for the length measuring device 1 previously proposed by the inventor.

Further, as a material forming the length measuring device 1,
Although metal or plastic can be used, the use of ceramics can make the length measuring device 1 more excellent. For example, if the piston 2, the rod 4, the cylinder 10, and the injection nozzle 5 are made of alumina ceramics, the weight can be reduced to 1/3 as compared with a metal one, so the followability of the piston 2 is greatly improved. Can be made. In addition, even when used at high temperatures, alumina ceramics do not cause deformation of the length measuring instrument 1 due to its small coefficient of thermal expansion, and also have excellent corrosion resistance compared to metals and plastics. Therefore, even when measuring in a humid place or when using a gas other than air as the working medium, the length measuring device 1 does not corrode, and the length measuring device 1 can be used regardless of the measuring environment or working medium. can do.

However, it goes without saying that the material of the length measuring device 1 may be not only alumina ceramics but also other ceramics such as silicon carbide, silicon nitride and sapphire.

As described above, the non-contact type length measuring device 1 of the present invention
Since high-pressure air pressure from the supply hole 11 is directly ejected from the ejection nozzle 5, the sensitivity of the length measuring instrument 1 can be improved. Moreover, the back pressure from the DUT 50 is taken into the second pressurizing chamber 7 through the second through hole 2b formed in the rod 4, and the piston 2 is supported by static pressure so that the piston 2 can follow the followability. Since the height is increased, it is possible to further reduce the variation in the measured value, and it is possible to provide a compact length measuring instrument 1 because a tube unlike the conventional case is not required.

[Experimental Example] Using the non-contact type length-measuring device 1 of the present invention shown in FIG. 1, an experiment was conducted on the variation of the measured value and the linearity of the measuring stroke.

The main dimensions of the length measuring instrument 1 are as follows.

Piston 2 cross section 12 × 30 mm,
Pressure receiving area 360mm ² Measuring stroke 10mm The diameter of the injection nozzle 5 is 0.5mm and 0.8m.
m and 2.0 mm were prepared and measured.

Then, in the supply hole 11 of the length measuring device 1, 0.
A pressure of about 7 kg / cm ² was supplied, and block gauges of 1 to 9 mm were sequentially measured. The linearity of the measurement stroke at this time is as shown in FIG. 4, and the variation of the measured value is as shown in FIG.

First, as can be seen from the graph of FIG. 4 showing the dispersion of measured values, there was almost no measurement error in the measurement of each block gauge, and very high linearity was obtained.

Further, as can be seen from the graph of FIG. 5 showing the linearity, the variation width of the measured value is at most 0.15 μm.
There is almost no difference from the following.

[0053]

As described above, according to the present invention, the piston is movably arranged in the cylinder, and the injection nozzle is provided at the tip of the rod protruding from the piston. In addition to the static pressure supporting means for supporting, the detecting means for detecting the displacement amount of the piston, and the adjusting means for adjusting the pressure of one first pressurizing chamber of the two pressurizing chambers formed vertically by the piston, The piston is provided with a first through hole connecting the tip of the rod and the side wall surface of the piston and a second through hole connecting the tip of the rod and the second pressurizing chamber. Since the high-pressure air pressure supplied for supporting can be jetted directly from the jet nozzle, the jet pressure from the jet nozzle can be increased and a highly sensitive length measuring device can be obtained. Further, since the back pressure from the object to be measured is taken in through the second through hole formed in the piston or rod, the back pressure does not fluctuate as the piston moves, and the measured value Can be further reduced. Moreover, because it does not require a tube as in the past, it is possible to greatly reduce the size of the entire length measuring device, and it is a highly accurate non-contact type length measuring device that can detect even weak back pressure changes. Can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view in which a part of a non-contact type length measuring device according to the present invention is cut away.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a longitudinal sectional view showing another non-contact type length measuring device according to the present invention.

FIG. 4 is a graph showing the linearity of the non-contact length measuring device according to the present invention.

FIG. 5 is a graph showing the dispersion of measured values of the non-contact type length measuring device according to the present invention.

FIG. 6 is a vertical cross-sectional view showing the previously proposed non-contact type length measuring device of the present invention.

FIG. 7 is a vertical sectional view showing a conventional non-contact type length measuring device.

FIG. 8 is a vertical sectional view showing a conventional non-contact type length measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Non-contact type length measuring machine 2 ... Piston 2a ... 1st through-hole 2b ... 2nd through-hole 2c ... Throttling part 2f ... Opening 3 ... Throttling groove 4 ... Rod 5 ... Injection nozzle 6 ... Linear encoder 7 ... Lower part Pressurizing chamber 8 ... Upper pressing chamber 9 ... Exhaust throttle valve 10 ... Cylinder 11 ... Supply hole

Claims (1)

[Claims] 1. A piston is movably arranged in a cylinder, an injection nozzle is provided at the tip of a rod projecting from the piston, and gas is supplied to the cylinder in a gap between the side wall surface of the piston. The static pressure supporting means and the detecting means for detecting the displacement amount of the piston, and the pressure adjusting means for adjusting the pressure of one of the two pressurizing chambers formed vertically by the piston are provided. The piston has a first through hole connecting the tip of the rod and the side wall surface of the piston, and a second through hole connecting the tip of the rod and the second pressure chamber.
Of the injection nozzle to eject gas toward the object to be measured, the shape of the object to be measured, the dimensions, the shape of the object to be measured with the displacement amount of the piston according to the surface state,
A non-contact type length measuring device that measures dimensions, surface conditions, etc.