JP3511679B2 - Surface roughness detection device and surface roughness detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum type surface roughness detecting device and a surface roughness detecting method suitable for detecting the surface roughness of a magnetic tape or the like.

[0002]

2. Description of the Related Art A three-dimensional surface roughness meter is used to measure the surface roughness of a sheet-shaped object to be measured such as a magnetic tape. With this three-dimensional surface roughness meter, the range that can be measured at one time is about 0.1 mm ² . If this is repeated many times, there is no limit to the size of the measurement surface. However, although this three-dimensional surface roughness meter accurately detects a narrow range of surface roughness, that is, a microscopic surface roughness, it has a wide range of surface roughness of the magnetic tape, that is, a macroscopic surface roughness. When detecting the height, there is a problem that it takes time and labor because the detection work must be performed many times. Therefore,
A vacuum suction type surface roughness meter has been developed to detect macroscopic surface roughness.

The vacuum suction type surface roughness meter is formed by, for example, flattening the surface of hard glass to form an optical flat, and mounting a magnetic tape or the like on it. Then, the air between the optical flat and the magnetic tape is sucked, and the surface roughness of the magnetic tape is detected based on the time until the magnetic tape completely adheres to the optical flat. For example, when the surface roughness of the magnetic tape is rough, the gap between the optical flat and the magnetic tape is large and the suction resistance is small, so that the air is quickly extracted, and thus the time during which the magnetic tape adheres is shortened. On the other hand, when the surface roughness is small, the suction resistance increases, so that the air escapes slowly and the contact time becomes long. The judgment as to whether or not the magnetic tape is in close contact is made visually. That is, when there is no air trap between the optical flat and the magnetic tape, it is determined that they are in close contact.

[0004]

Such a surface roughness meter is still in the stage of development, and the present condition is that the measurement accuracy is not clearly displayed. Therefore, even if the surface roughness of a magnetic tape or the like is measured by this device, it is not clear how much the error is, and there is a problem that it can be used only for reference.

Further, in a high-speed dubbing apparatus for magnetic tape, the winding characteristic of the magnetic tape is a very important factor. That is, the winding characteristics of the magnetic tape due to the surface roughness greatly affect the winding speed of the magnetic tape. However, the microscopic measurement value of the conventional three-dimensional surface roughness meter can be used only for reference as described above, and there is a problem that the surface roughness of the magnetic tape cannot be accurately detected.

Therefore, the present invention has been made to solve the above-mentioned problems, and is a vacuum suction system capable of eliminating the cause of measurement error and further clarifying the error range to improve the reliability of measurement data. The present invention proposes a surface roughness detecting device and a surface roughness detecting method.

[0007]

In order to solve the above-mentioned problems, in the invention described in claim 1, a sheet-shaped object to be measured is fixed on a reference surface, and the reference surface and the object to be measured are fixed. A measuring unit capable of bleeding air between the object to be measured, a desiccator that is an airtight chamber connected to the measuring unit, and a vacuum pump for sucking air in the desiccator are provided, and the measuring unit and the desiccator are connected to each other. A valve is provided in the piping, and the valve is opened while the inside of the desiccator is kept at a predetermined vacuum level by a vacuum pump, so that the air present between the reference surface and the object to be measured is sucked to It is characterized in that the surface roughness of the object to be measured is determined based on the contact time with the object to be measured.

According to a twenty-second aspect of the present invention, a sheet-like object to be measured is placed on a reference surface provided in the measuring section,
With the inside of the desiccator, which is an airtight chamber connected to the vacuum pump by piping, maintained at a predetermined vacuum level by the vacuum pump,
By opening the valve provided in the pipe that connects the measuring unit and the desiccator, the air that is present between the reference surface and the DUT is sucked in, and the air is absorbed based on the contact time between the DUT and the reference surface. In the surface roughness detection method that determines the surface roughness of the measured object, the reference vacuum degree reached by the inside of the desiccator is measured when measuring the roughness of the surface roughness detection device, and the fluctuation component is added to the reference vacuum degree for sucking air. Or, the upper and lower vacuum levels are calculated by subtracting, and the upper vacuum level when sucking air,
Calculate the time to reach the lower limit vacuum and the reference vacuum, and calculate the difference between the time to reach the upper limit vacuum and the time to reach the reference vacuum and the time to reach the lower limit vacuum and the time to reach the reference vacuum. Is used as the measurement error of the surface roughness measurement value.

In a twenty-eighth aspect of the present invention, a sheet-shaped object to be measured is placed on a reference surface provided in the measuring section,
With the inside of the desiccator, which is an airtight chamber connected to the vacuum pump, maintained at a predetermined vacuum level by the vacuum pump, open the valve provided in the pipe that connects the measuring unit and the desiccator to measure the reference surface and the measured object. By sucking air intervening between the object and the surface roughness detecting method for determining the surface roughness of the object to be measured based on the contact time between the object to be measured and the reference surface, in the reference surface and the object to be measured. It is characterized in that the contact area is changed according to the object to be measured.

[0010]

As shown in FIG. 1, the pressure P is generated in the desiccator 12.
From the time when the electromagnetic sluice valve 15 is opened in the state of being held at 1, until the air in the suction chamber 23 of the measuring section 11 shown in FIG. 2 is sucked out and the object to be measured 19 comes into complete contact with the optical flat 20. The time T is measured by the timer 30A, and the surface roughness of the object to be measured 19 is determined based on the contact time T. The relationship between the contact time T and the surface roughness is measured in advance, and the surface roughness is determined by this.

Further, here, the upper limit vacuum degree (P1) 'of the reference pressure P1 due to the pressure fluctuation ΔP1 in the desiccator 12 is set.
And the time t ″ at which the lower limit vacuum (P1) ″ is reached are calculated by Equation 3, and the error range δ is also calculated by Equation 4. This error range δ is the maximum error of the contact time T. As described above, in the present invention, the error range δ of the contact time T becomes clear, so that the reliability of the measurement data is improved.

[0012]

Embodiments of the surface roughness detecting device and the surface roughness detecting method according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the configuration of a first embodiment of a surface roughness detecting device 1 according to the present invention. This surface roughness detector 1
Is a vacuum suction type surface roughness detection device, and is used for macroscopically detecting the surface roughness of a sheet-shaped object to be measured 19 (FIG. 2) such as a magnetic tape. Surface roughness detector 1
Is composed of a vacuum unit 10 for sucking air and a measuring unit 11 in which a fixed object 19 is arranged. The vacuum unit 10 is equipped with a desiccator 12 which is an airtight chamber for maintaining a predetermined degree of vacuum, and a vacuum pump 13. The measuring unit 11 and the desiccator 12 are connected to the pipe 14.
The electromagnetic sluice valve 15 and the flow rate control valve 32, which are electrically connected to each other and are electrically opened and closed, are provided in the middle of the pipe 14. Further, the desiccator 12 and the vacuum pump 13 are connected by a pipe 16, and a partition valve 17 and a flow rate control valve 33 are interposed in the middle of the pipe 16. Measuring unit 11 and desiccator 1
Vacuum gauges 18 and 34 and leak valves 35 and 36 are attached to the unit 2, respectively. The leak amounts of the leak valves 35 and 36 can be adjusted by a micrometer head or the like. Further, the surface roughness detecting device 1 has an operation unit 30 for controlling opening / closing of the electromagnetic sluice valve 15, and a timer 30A is provided therein. Then, by operating the push button 30B of the operation unit 30, the electromagnetic sluice valve 15 is opened and closed, and the timer 30A is operated accordingly. Here, the time from when the electromagnetic sluice valve 15 is opened to when it is closed can be measured.

When measuring the surface roughness with the surface roughness detecting device 1, the vacuum pump 13 is operated to operate the desiccator 12.
To a predetermined vacuum degree. Then, in a state where the desiccator 12 is maintained at a predetermined vacuum degree, the electromagnetic sluice valve 15 is opened to suck the air in the measuring section 11 to the desiccator 12 side.
As shown in FIG. 2, the measuring section 11 is an optical flat 20 on which a sheet-shaped object 19 such as a magnetic tape is placed.
A base 21 for supporting the optical flat 20 and a holding portion 22 for holding the fixed object 19.

The optical flat 20 is made by polishing a very hard material such as hard glass to make its surface flat. By removing air from the object 19 to be measured, the object 20 to be measured is removed. It is possible to completely adhere 19 together. A suction chamber 23 is provided around the optical flat 20, and the air therein is sucked by the desiccator 12. The fixed object is placed on the flange portion 24 around the suction chamber 23 of the optical flat 20 and the base 21, and the pressing portion 22 is arranged on the flange portion 24 and fastened with the bolt 25. An O-ring 26 is interposed between the flange portion 24 and the pressing portion 22, and the inside of the suction chamber 23 is sealed by this. Further, a taper portion 28 is provided on the outer peripheral portion of the optical flat 20, so that the object to be measured 19 can be easily set at the measurement position without being hooked on the optical flat 20, and the residual air 27 is generated. Since it is easy to come off, reproducibility of measurement is improved. Although hard glass is used as the material of the optical flat 20 in this example, a ceramic material such as alumina or altic may be used.

The optical flat 20 is formed in a disc shape as shown in FIG. 3, and the suction chamber 23 is arranged so as to surround the periphery of the optical flat 20. Therefore, when the air in the suction chamber 23 is sucked, the air between the object 19 to be measured and the optical flat 20 is extracted, and the object 19 to be adhered adheres to the optical flat 20. The flange portion 24 and the pressing portion 22 are rectangular.

In order to detect the surface roughness of the object 19 to be measured, first the vacuum pump 13 is operated and the leak valve 35 is adjusted while checking the vacuum gauge 34 (FIG. 1) to adjust the desiccator 12 to a predetermined vacuum. Hold every time. Next, the side item 1
The part for detecting the surface roughness of 9 is an optical flat 20
It is placed on the upper side, and its periphery is placed on the flange portion 24 of the base 21. Then, the pressing portion 22 is fastened with the bolt 25, and the suction chamber 23 is completely sealed with the object to be measured 19. Here, when the push button 30B is operated to open the electromagnetic sluice valve 15, the air in the suction chamber 23 of the base 21 is released.
It is sucked to the 2 side. At this time, the timer 30A starts time measurement in conjunction with the opening of the electromagnetic sluice valve 15. Immediately after the suction is started, as shown in FIG. 4 (A), the fixed object 19 is closely attached to the outer peripheral side of the optical flat 20,
Air remains in a wide area of the optical flat 20.

When the object to be measured 19 is brought into close contact with the outer peripheral side of the optical flat 20 in this way, the resistance of the close contact portion increases and the time for extracting the residual air 27 becomes relatively long. In particular, the smoother the surface of the object to be measured 19 is, the larger the resistance is, so that the time for extracting the residual air 27 becomes longer. As the suction progresses, as shown in FIG.
The amount of close contact between the optical flat 20 and the optical flat 20 increases, and a small amount of residual air 27 exists at the center of the optical flat 20 immediately before the complete close contact. As the suction progresses further, Fig. 2
As shown in (3), all the residual air 27 is sucked out, and the object to be measured 19 completely adheres to the optical flat 20. Therefore, the state of the residual air 27 is observed, and when the residual air 27 disappears, it is determined that the object to be measured 19 is in complete contact with the optical flat 20. Push button 3 again in this state
By pressing 0B and closing the electromagnetic sluice valve 15,
The timer 30A linked with this completes the time measurement, and the time required for complete contact between the object to be measured 19 and the optical flat 20 is obtained. After measurement, leak valve 36
By adjusting the inflow of air into the suction chamber 23 and slowly bringing the inside of the suction chamber 23 into the atmospheric state, the object to be measured 19 can be removed without damage.

In the surface roughness detecting apparatus 1, the desiccator 12 is maintained in a low vacuum of, for example, about 2 mmHg, the electromagnetic sluice valve 15 is opened, and then the DUT 1 is measured.
The surface roughness of the object to be measured 19 is judged on the basis of the time T until 9 is completely adhered to the optical flat 20. That is, the rougher the surface of the object to be measured 19, the larger the gap between the object to be measured 19 and the optical flat 20, so that the resistance for sucking out the residual air 27 becomes small, and the time T until the object to be measured 19 completely adheres becomes shorter. Become. On the contrary, the object to be measured 19
The smoother the surface of, the longer the time T until the object 19 to be measured comes into complete contact. Then, the surface roughness of the object to be measured 19 is determined by comparing the measured adhesion time T with a roughness determination table or the like. Further, in the surface roughness detecting device 1, the error range δ of the surface roughness can be clarified as described below.

Here, as shown in FIG.
The reference pressure inside is P1 (Pa), and the pressure fluctuation component is ΔP1
(Pa), the volume is V1 (m ³ ), the pressure of the measuring unit 11 is P2 (Pa), the volume is V2 (m ³ ), the ultimate pressure of the vacuum pump 13 is P0 (Pa), and the exhaust speed is S0 ( m ³
/ Sec). Strictly speaking, the pressure fluctuation component ΔP2 of the measuring unit 11 and the ultimate pressure fluctuation component ΔP0 of the vacuum pump 13 exist, but they are so small that they can be ignored.

Now, the conductance of the pipe 16 between the desiccator 12 and the vacuum pump 13 is C1 (m ³ / se).
c) If the conductance of the pipe 14 between the measuring unit 11 and the desiccator 12 is C2 (m ³ / sec), the exhaust speed S1 of the desiccator 12 and the measuring unit 11 when the pressure inside the desiccator 12 is the reference pressure P1. The exhaust speed S2 is represented by Formula 1.

[0022]

[Equation 1]

Further, the pressure fluctuation ΔP1 in the desiccator 12
And the upper limit pressure is (P1) ′ = (P1 + ΔP
1) and the lower limit pressure is (P1) ″ = (P1−ΔP1), the exhaust speed (S1) ′ of the desiccator 12 and the exhaust speed (S of the measurement unit 11 with respect to the upper limit pressure (P1) ′.
2) ', and the desiccator 1 for the lower limit pressure (P1) "
2 exhaust speed (S1) "and the exhaust speed of the measuring unit 11 (S
2) ”is calculated by Equation 2. Here, the ones with (') attached to each symbol represent the specifications for the upper limit pressure (P1)', and the ones with (") to the lower limit pressure (P1). ) ”
Represents the specifications for. This also applies to the following description.

[0024]

[Equation 2]

Now, the low vacuum region (100 Pa or more, 1 m
mHg = 133.322 Pa), and the pressure in the desiccator 12 is the reference pressure P1, the time until the pressure in the measurement unit 11 reaches the ultimate pressure PKT = P1 from the pressure P2 is t (sec). Further, when the pressure inside the desiccator 12 is the upper limit pressure (P1) ', the pressure inside the measuring unit 11 is the pressure P.
The time from reaching 2 to the ultimate pressure (PKT) '= (P1)' is t '(sec), and when the pressure in the desiccator 12 is the lower limit pressure (P1) ", the pressure in the measuring unit 11 changes from the pressure P2. Assuming that the time required to reach the ultimate pressure (PKT) ″ = (P1) ″ is t ″ (sec), these times t,
t ′ and t ″ are represented by Formula 3. However, the upper limit pressure (P
The exhaust speed of the measuring unit 11 at 1) 'is (S2)', and the exhaust speed of the measuring unit 11 at the lower limit pressure (P1) is (S).
2) ”.

[0026]

[Equation 3]

Now, when the pressure of the desiccator 12 fluctuates between the upper limit pressure (P1) 'and the reference pressure P1,
When the error between the time t to reach the reference pressure P1 and the time t'to reach the upper limit pressure (P1) 'is δJ, when the pressure in the desiccator 12 changes from the reference pressure P1 to the lower limit pressure (P1) ", The difference between the time t at which the reference pressure P1 is reached and the time t "at which the lower limit pressure (P1) is reached is δK. Further, the maximum pressure fluctuation in the desiccator 12, that is, the upper limit pressure (P1) 'to the lower limit pressure (P1)". When the maximum error in the time to reach the ultimate pressure when fluctuating up to is δ, the error δ
J, δK, δ are expressed by Equation 4. However, P0, P2,
It is assumed that there is no change in V2.

[0028]

[Equation 4]

Here, the reason why the ultimate pressure of the desiccator 12 is set to a relatively low vacuum of 2 mmHg is that the desiccator 1
This is because the air in 2 is extracted as quickly as possible to shorten the measurement time, and if this is set to a high vacuum degree, it takes a long time to reach the ultimate vacuum degree, which causes a problem that the measurement time becomes long.

Now, assuming that the flow when the air in the measuring section 11 is sucked from the desiccator 12 is in a viscous flow state, the pipe 16 between the desiccator 12 and the vacuum pump 13, the measuring section 11 and the desiccator 12 are connected. The conductances C1 and C2 when the pipe 14 between them is a circular pipe are obtained. Actually, since the electromagnetic type sluice valve 15, the sluice valve 17, the flow rate control valves 32, 33, etc. are put in, it is necessary to obtain a combined conductance including them, but here, in order to simplify the description, the conductance of only the pipes 16, 14 is used. Calculate C1 and C2.

The inner diameter of the pipe 16 between the desiccator 12 and the vacuum pump 13 is D1 (m) and the length is L1 (m),
When the inner diameter of the pipe 14 between the measurement unit 11 and the desiccator 12 is D2 (m) and the length is L2 (m), the conductances C1 and C2 are represented by Formula 5.

[0032]

[Equation 5]

Here, an example of calculating the surface roughness of the object to be measured 19 and its error range by using the above equations 1 to 5 will be described. Here, the specification of each part is Equation 6
The case represented by will be described.

[0034]

[Equation 6]

First, the pressure in the desiccator 12 is the upper limit pressure (P1) '= (P1 + ΔP1) = (2 + 0.2) (mm
In the case of Hg) ≅293.31 (Pa), the ultimate pressure, that is, the time t ′ for reaching the upper limit pressure (P1) ′ is calculated.
This time t ′ is obtained by substituting the equation 6 into the equations 1 to 5, and the result is represented by the equation 7.

[0036]

[Equation 7]

Next, the pressure in the desiccator 12 is the lower limit pressure (P1) "= (P1-.DELTA.P1) = (2-0.2) (mm
When Hg) ≈239.98 (Pa), the ultimate pressure, that is, the time t "at which the lower limit pressure (P1)" is reached is calculated.
This time t ″ is also calculated by substituting the equation 6 into the equations 1 to 5, and the result is represented by the equation 8.

[0038]

[Equation 8]

Subsequently, the pressure inside the desiccator 12 is the reference pressure P1 = 2.0 (mmHg) = 266.644 (Pa).
In this case, the time t at which the ultimate pressure, that is, the reference pressure P1 is reached is calculated. This time t is also calculated by substituting Equation 6 into Equations 1 to 5, and the result is represented by Equation 9.

[0040]

[Equation 9]

From the results of Equations 7 to 9, the pressure in the desiccator 12 is changed from the upper limit pressure (P1) 'to the reference pressure P.
The error of the time to reach the ultimate pressure when fluctuating up to 1 (δ
J), the error (δK) in the time to reach the ultimate pressure when varying from the reference pressure P1 to the lower limit pressure (P1) ", and the ultimate pressure when varying from the upper limit pressure (P1) 'to the lower limit pressure (P1)" The error δ of the reaching time is expressed by Expression 10.

[0042]

[Equation 10]

In this example, when the inner diameters D1 and D2 of the pipe 16 and the pipe 14 are 0.004 m as described above, the time T during which the object 19 to be measured is brought into close contact with the optical flat 20 is measured. The surface roughness of the measurement object 19 is determined. Further, here, the time t until reaching the ultimate pressure is reached.
The error ranges δJ, δK, and δ are detected as the error ranges of the contact time T.

That is, what appears as an error of the contact time T is due to the pressure fluctuation of the desiccator 12, which is the ultimate pressure, that is, the reference pressure P1 and the upper limit pressure (P
1) ', the time t, t', at which the lower limit pressure (P1) "is reached,
The pressure of the desiccator 12 changes at the start of measurement, but is not included in the error factors other than the difference in the initial value of the pressure inside the desiccator 12 before measurement. The time including the error due to the initial pressure value is up to the time when the ultimate pressure value is reached, and the time from when the ultimate pressure is reached until the measured object 19 comes into close contact with the optical flat 20 does not become an error. In the present invention, since the error range of the surface roughness becomes clear, the reliability of the measurement data becomes high.

Similarly to the above, the adhesion time T when the inner diameters D1 and D2 of the pipes 16 and 14 are 0.011 m is measured to obtain the surface roughness. Also in this case, the upper limit pressure (P
1) 'and lower limit pressure (P1) "time t',
t "and the maximum error range δ are calculated. The result is Formula 11. Furthermore, the adhesion time T when the inner diameters D1 and D2 of the pipes 16 and 14 are 0.0075 m and the upper limit pressure (P
1) 'and time t', t "to reach the lower limit pressure (P1)"
And the maximum error range δ is calculated, and the result is Formula 1
It is represented by 2.

[0046]

[Equation 11]

[0047]

[Equation 12]

[0048] In summary of the results is as follows.
That is, the pressure in the desiccator 12 is the reference pressure P1 ± 1.
In the case of 0% (= 2 mmHg ± 0.2 mmHg), the error range δ of the time T in which the measured object 19 is brought into close contact with the optical flat 20 is 0.0 for the inner diameters D1 and D2 of the pipes 16 and 14.
When 04m, δ = ± 6.42 (sec), inner diameter D1, D
When 2 is 0.075 m, δ = ± 0.54 (sec), and when inner diameters D1 and D2 are 0.11 m, δ = ± 0.14 (se
c). From this result, the error range δ is
Inner diameters D1 and D2 of the coil, that is, conductances C1 and C
It turns out that it depends on 2.

That is, the factor that causes the variation in the measurement precision is the pressure precision ΔP1 in the desiccator 12, and the factor that determines the absolute value thereof is the conductance C of the pipes 16 and 14.
1 and C2. When the pipes 16 and 14 are circular pipes, the pipe inner diameters D1 and D2 largely depend on the measurement accuracy. When the inner diameters D1 and D2 of the pipes 16 and 14 are changed, the measuring unit 11
The exhaust speed S2 of the above changes, and the time T until the measured object 19 completely adheres to the optical flat 20 changes. Therefore, when it is desired to measure the surface roughness quickly or to improve the measurement accuracy, the inner diameters D1,
It can be seen that it is sufficient to increase D2.

In practice, the combined conductance in consideration of the conductances of the electromagnetic sluice valve 15, the sluice valve 17, the flow rate control valves 32, 33, etc. is obtained, and the fluctuation component ΔP1 of the pressure P1 in the desiccator 12 is calculated. The measurement accuracy of the surface roughness detection device 1 must be determined by measuring after manufacture, determining the control accuracy of the vacuum pressure P1 and substituting this into the general formulas of Formula 1 to Formula 5. Further, when the vacuum pressure P1 in the desiccator 12 is controlled by a commercially available digital vacuum constant device, a solenoid valve, or the like, the set value here may be substituted into Expressions 1 to 5. However, in order to eliminate the error factor after the start of measurement, it is necessary to perform control to stop the control function after the start of measurement.

Therefore, in the surface roughness detecting apparatus 1, the conductances between the desiccator 12 and the vacuum pump 13 and between the measuring section 11 and the desiccator 12 are adjusted by adjusting the flow rate adjusting valves 32 and 33. It is possible. It is clear from Expression 1 that the exhaust speed S1 of the desiccator 12 and the exhaust speed S2 of the measuring unit 11 can be controlled by adjusting the conductance. Therefore, for example, the measured object 19 measured in 60 seconds
Can be remeasured in 90 seconds, or the measurement time of the same object to be measured 19 can be changed for the convenience of the user. That is, by setting the length of the measurement time appropriately,
The resolution of measured values can be improved.

However, since the flow rate control valves 32 and 33 are not fixed, the conductance between the desiccator 12 and the vacuum pump 13 and between the measuring section 11 and the desiccator 12 may change. When more precise measurement values are required, fixed orifices (not shown) may be provided instead of the flow rate control valves 32 and 33. By making this fixed orifice replaceable, the conductance can be adjusted. Alternatively, by connecting only the pipes 14 and 16 without using the fixed orifice, change in conductance can be eliminated and more precise measurement can be performed. In this case, the conductance can be adjusted by making the pipes 14 and 16 exchangeable.

After the surface roughness detecting device 1 is manufactured,
Electromagnetic gate valve 15, gate valve 17 and flow control valve 3
The combined conductance in consideration of the conductances of 2, 33, etc., the effective pumping speed of each part and the vacuum pressure P1 ± ΔP1 in the desiccator 12, the desiccator 12 and the measuring part 1
It is possible to determine the actual measurement accuracy of the device 1 by measuring the exhaust speeds S1 and S2 and substituting them into the formulas 1 to 5. The actual measurement accuracy here is preferably determined in consideration of variations in the accuracy of the vacuum gauge 18 and the response accuracy of the electromagnetic sluice valve 15, the sluice valve 17, the flow rate control valves 32, 33, and the like.

In the surface roughness detecting apparatus 1, the measurement resolution is improved by increasing the area of the contact surface 29 between the optical flat 20 and the object to be measured 19 while keeping the volume V2 in the measuring section 11 constant. Can be made. That is, the surface roughness detecting device 1 according to the present invention is designed to remove residual air 2
The degree of escape of No. 7 is measured with time, and the minute volume of the residual air 27 is replaced with time. As described above, if the error range of the measurement error is limited with respect to the specified pressure in the desiccator 12, the desiccator 1
Since the error is in the range up to the ultimate pressure value within 2 or within the measuring unit 11, the error is not included after the ultimate pressure value. Therefore, in the surface roughness detecting device in which the error range is guaranteed, the measurement accuracy does not change even if the contact surface 29 is increased if the volume V2 in the measuring unit 11 is the same. That is, the measurement time becomes longer as the area of the contact surface 29 becomes larger, and as a result, the difference due to the escape of the residual air 27 becomes clear.

FIG. 5 shows the structure of the measuring unit 41 in the second embodiment to which the present invention is applied. The measuring unit 41 is made such that the optical flat 20 can be replaced. This optical flat 20 is attached to a mounting base 31,
The mount 31 is removable from the base 21. At the time of measurement, the optical flat 20 corresponding to the required accuracy of the measured value is selected from the plurality of optical flats 20 having different areas, and the mounting base 31 is fixed to the base 21 by the bolt 32 from the lower surface. When the plurality of optical flats 20 are attached to the measuring unit 11, the volume of the suction chamber 23 in the measuring unit 11 is constant.
Since the area of the contact surface 29 can be changed by exchanging the optical flat 20, the resolution of the measured value can be improved according to the object to be measured 19.

FIG. 6 shows the structure of the measuring unit 42 of the third embodiment to which the present invention is applied. The measuring part 42 uses a quick coupling type clamp 38 for fastening the flange part 24 and the pressing part 22. As shown in FIG. 7, in this case, the flange portion 24 and the pressing portion 22 are formed in a circular shape. Further, the clamp 38 can be opened and closed to the left and right by a shaft 39 for easy mounting. After placing the DUT 19 on the flange 24,
The clamp 38 is attached to the flange portion 24 and the pressing portion 22, and the set screw 40 is tightened and fastened. By using the clamp 38, the object to be measured 19 can be easily fixed.

Further, in the surface roughness detecting device 1,
By providing a bypass pipe (not shown) having a diameter larger than this between the desiccator 12 and the vacuum pump 13 in addition to the pipe 16, by switching to this bypass pipe when the contact area becomes larger than a predetermined value. , It is possible to improve the efficiency of repeated measurements. Further, by using a digital vacuum constant holding device (not shown) for the vacuum pump 13 and keeping the inside of the desiccator 12 at a specified pressure by digital control, it is possible to further improve the accuracy of the measured value. . Further, the leak valve 35 attached to the desiccator 12 may be a non-adjustable one dedicated to maintenance. In this case, the initial pressure P1 in the desiccator 12 is set to the ultimate pressure by the vacuum pump 13, so that the ultimate pressure becomes a constant value because the volume and the gas discharge amount for a low vacuum are constant. Therefore,
It is possible to eliminate causes of errors other than human factors and variations in accuracy of each part that constitutes the device.

Further, a laser displacement meter (not shown) may be installed at the center of the object to be measured 19. This laser displacement meter starts measurement of the highest position of the object to be measured 19 which changes according to the residual air 27 present between the optical flat 20 and the object to be measured 19 when the measurement is started. Then, when the position when the residual air 27 disappears is detected, the timer 30A ends the time measurement. This makes it possible to eliminate human error. Alternatively, an autofocus device may be used instead of this laser displacement meter.

[0059]

As described above, according to the first aspect of the present invention, the sheet-like object to be measured is fixed on the reference surface, and the air between the reference surface and the object to be measured is fixed. Equipped with a measuring unit that can be pulled out, a desiccator that is an airtight chamber connected to the measuring unit, and a vacuum pump that sucks air in the desiccator, and a valve is provided in the pipe that connects the measuring unit and the desiccator. By opening the valve while keeping the desiccator inside the desiccator at the specified vacuum level, the air that is present between the reference surface and the DUT is sucked in, and the contact time between the reference surface and the DUT is reduced. The surface roughness of the object to be measured is determined based on. Therefore, according to the present invention, it is possible to eliminate the factor of the error and further clarify the error range to improve the reliability of the measurement data.

According to a twenty-second aspect of the present invention, a sheet-like object to be measured is placed on the reference surface provided in the measuring section,
With the inside of the desiccator, which is an airtight chamber connected to the vacuum pump by piping, maintained at a predetermined vacuum level by the vacuum pump,
By opening the valve provided in the pipe that connects the measuring unit and the desiccator, the air that is present between the reference surface and the DUT is sucked in, and the air is absorbed based on the contact time between the DUT and the reference surface. In the surface roughness detection method that determines the surface roughness of the measured object, the reference vacuum degree reached by the inside of the desiccator is measured when measuring the roughness of the surface roughness detection device, and the fluctuation component is added to the reference vacuum degree for sucking air. Or, the upper and lower vacuum levels are calculated by subtracting, and the upper vacuum level when sucking air,
Calculate the time to reach the lower limit vacuum and the reference vacuum, and calculate the difference between the time to reach the upper limit vacuum and the time to reach the reference vacuum and the time to reach the lower limit vacuum and the time to reach the reference vacuum. Is used as the measurement error of the surface roughness measurement value. Therefore, according to the present invention, not only the measurement error due to theoretical calculation but also the error of the actual measurement value can be obtained, and it is possible to improve the reliability of the measurement data.

According to a twenty-eighth aspect of the present invention, a sheet-shaped object to be measured is placed on the reference surface provided in the measuring section,
With the inside of the desiccator, which is an airtight chamber connected to the vacuum pump, maintained at a predetermined vacuum level by the vacuum pump, open the valve provided in the pipe that connects the measuring unit and the desiccator to measure the reference surface and the measured object. By sucking air intervening between the object and the surface roughness detecting method for determining the surface roughness of the object to be measured based on the contact time between the object to be measured and the reference surface, in the reference surface and the object to be measured. The contact area is changed according to the object to be measured. Therefore, according to the present invention, it is possible to improve the resolution according to the object to be measured while maintaining the accuracy of the measured value.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a surface roughness detecting apparatus 1 according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a measuring unit 11.

FIG. 3 is a cross-sectional view of the measuring unit 11.

FIG. 4 is a diagram showing a contact process of an object to be measured 19.

FIG. 5 is a configuration diagram of a measuring unit 41 of a second embodiment according to the present invention.

FIG. 6 is a configuration diagram of a measuring unit 42 according to a third embodiment of the present invention.

7 is a top view of the measuring unit 42. FIG.

[Explanation of symbols]

1 Surface roughness detector 10 vacuum unit 11,41,42 Measuring unit 12 desiccators 13 Vacuum pump 14, 16 piping 15 Electromagnetic gate valve 19 DUT 20 optical flat 23 Suction chamber 27 Residual air 28 Tapered part 29 Contact surface 30 Operation part 30A timer 30B push button 31 mounting base 32, 33 Flow control valve 35,36 Leak valve 38 Clamp

Claims (28)

(57) [Claims] 1. A measuring unit capable of fixing a sheet-shaped object to be measured placed on a reference surface and removing air between the reference surface and the object to be measured, and the measuring unit. A desiccator that is an airtight chamber connected to, and a vacuum pump that sucks air in the desiccator, and a valve is provided in a pipe that connects the measuring unit and the desiccator, and the vacuum pump is used to set a predetermined inside of the desiccator. By opening the valve while maintaining the degree of vacuum, the air that is present between the reference surface and the object to be measured is sucked,
A surface roughness detecting device, characterized in that the surface roughness of the object to be measured is determined based on the contact time between the reference surface and the object to be measured. 2. The surface roughness detecting device according to claim 1, wherein the desiccator is provided with a leak valve capable of adjusting a flow rate. 3. The surface roughness detecting device according to claim 1, wherein the desiccator is provided with a leak valve whose flow rate cannot be adjusted. 4. The valve according to claim 1, wherein the valve is of an electromagnetic type, provided with a timer for measuring the contact time, and provided with operation means for controlling the valve and the timer at the same time. Surface roughness detector. 5. The surface roughness detecting device according to claim 1, wherein a valve whose opening degree is adjustable is provided in a pipe connecting the desiccator and the vacuum pump. 6. The surface roughness detecting device according to claim 1, wherein a valve whose opening degree is adjustable is provided in the pipe connecting the desiccator and the measuring unit. 7. The replaceable orifice is provided in the pipe connecting the desiccator and the vacuum pump.
The surface roughness detection device described. 8. The surface roughness detecting device according to claim 1, wherein a replaceable orifice is provided in the pipe connecting the desiccator and the measuring unit. 9. The surface roughness detecting device according to claim 1, wherein the pipe connecting the desiccator and the vacuum pump is replaceable. 10. The pipe for connecting the desiccator and the measuring unit is replaceable.
To the surface roughness detecting device according to claim 9. 11. The surface roughness detecting device according to claim 1, wherein the measuring unit is provided with a vacuum gauge. 12. The surface roughness detecting device according to claim 1, wherein a leak valve whose flow rate is adjustable is provided in the measuring unit. 13. The surface roughness detection according to claim 1, wherein fixing means for fixing the object to be measured to the reference surface is attached to the reference surface by a detachable clamp. apparatus. 14. The reference surface is an optical flat formed of a ceramic material.
To the surface roughness detecting device according to claim 13. 15. The surface roughness detecting device according to claim 1, wherein the reference surface is replaceable. 16. The suction volume in the measuring section becomes constant when the reference surface is exchanged.
5. The surface roughness detector according to item 5. 17. A bypass pipe, which is thicker than the pipe, is provided in the pipe connecting the desiccator and the vacuum pump, and the bypass pipe is provided when a contact area between the reference surface and the DUT increases to a predetermined value or more. The surface roughness detecting device according to claim 14 or 16, characterized in that: 18. The surface roughness detecting device according to claim 17, wherein the bypass pipe is provided with an automatically controlled electromagnetic valve. 19. The surface roughness detecting apparatus according to claim 1, wherein the desiccator is provided with a vacuum constant control means for maintaining a vacuum degree at a constant value. 20. A laser displacement meter and a timer interlocking with the laser displacement meter are provided in the measuring section, and the object to be measured that changes according to the amount of air present between the reference surface and the object to be measured. 20. The surface roughness detecting device according to claim 1, wherein a contact time between the reference surface and the object to be measured is detected by measuring a position. 21. An autofocus device and a timer interlocking with the autofocus device are provided in the measuring unit,
The contact time between the reference surface and the object to be measured is detected by measuring the position of the object to be measured that changes according to the amount of air present between the reference surface and the object to be measured. The surface roughness detecting device according to claim 1, wherein the surface roughness detecting device is a surface roughness detecting device. 22. A sheet-shaped object to be measured is placed on a reference surface provided in the measuring section, and the inside of a desiccator, which is an airtight chamber connected to a vacuum pump by piping, is maintained at a predetermined vacuum degree by the vacuum pump. In this state, by opening the valve provided in the pipe connecting the measuring unit and the desiccator, the air present between the reference surface and the object to be measured is sucked, and the object to be measured and the object to be measured. In the surface roughness detecting method for determining the surface roughness of the object to be measured based on the contact time with the reference surface, the reference vacuum degree reached in the desiccator at the time of measuring the roughness of the surface roughness detecting device is measured. , The fluctuation component is added to or subtracted from the reference vacuum degree for sucking the air to calculate the upper limit vacuum degree and the lower limit vacuum degree, and when the air is sucked, the upper limit vacuum degree, the lower limit vacuum degree and the reference vacuum degree are calculated. When it arrives Then, the difference between the time to reach the upper limit vacuum degree and the time to reach the reference vacuum degree, and the difference between the time to reach the lower limit vacuum degree and the time to reach the reference vacuum degree are calculated respectively. A method for detecting surface roughness, characterized in that the measurement error of the measured value is used. 23. The conductance between the desiccator and the vacuum pump and the conductance between the desiccator and the measuring unit are respectively measured, and the exhaust speed of the desiccator is calculated from the conductance between the desiccator and the vacuum pump. Calculate the exhaust rate of the measuring section from the conductance between the desiccator and the measuring section, the exhaust rate of the desiccator and the measuring section when the valve is opened, the upper vacuum degree, the 23. The surface roughness detecting method according to claim 22, wherein the lower limit vacuum degree and the time required to reach the reference vacuum degree are calculated respectively. 24. The evacuation speed of the measuring section is measured, and the time required to reach the upper limit vacuum degree, the lower limit vacuum degree and the reference vacuum degree when the valve is opened by the evacuation rate of the measuring section is set. 23. The surface roughness detecting method according to claim 22, wherein the surface roughness is calculated. 25. The reference vacuum degree reached by the measuring unit and the desiccator is measured, and the conductance between the desiccator and the vacuum pump and the conductance between the desiccator and the measuring unit are measured, respectively. The exhaust speed of the desiccator is calculated from the conductance between the desiccator and the vacuum pump, the exhaust speed of the measuring part is calculated from the conductance between the desiccator and the measuring part, and the exhaust of the desiccator and the measuring part is calculated. 23. The surface roughness detecting method according to claim 22, wherein the upper limit vacuum degree, the lower limit vacuum degree, and the time required to reach the reference vacuum degree when the valve is opened are calculated based on the speed. 26. The reference degree of vacuum reached by the measuring section and the desiccator is measured, the conductance between the desiccator and the measuring section is measured, the exhaust speed of the desiccator is measured, and the desiccator and the measurement are performed. Calculate the exhaust speed of the measurement unit from the conductance between the section, and the upper limit vacuum degree, the lower limit vacuum degree and the reference vacuum degree when the valve is opened by the exhaust rate of the desiccator and the measurement unit. 23. The surface roughness detecting method according to claim 22, wherein the time required for the arrival is calculated. 27. The reference degree of vacuum reached by the measuring unit and the desiccator is measured, the exhaust speed of the measuring unit is measured, and the upper limit vacuum degree when the valve is opened by the exhaust speed of the measuring unit, 23. The surface roughness detecting method according to claim 22, wherein the time required to reach the lower limit vacuum and the reference vacuum is respectively calculated. 28. A state in which a sheet-shaped object to be measured is placed on a reference surface provided in a measuring unit, and a desiccator, which is an airtight chamber connected to a vacuum pump, is maintained at a predetermined vacuum degree by the vacuum pump. In, by opening the valve provided in the pipe connecting the measuring unit and the desiccator, to suck the air interposed between the reference surface and the DUT,
In the surface roughness detecting method for determining the surface roughness of the measured object based on the contact time between the measured object and the reference surface, the contact area between the reference surface and the measured object is the measured object. A method for detecting surface roughness, which is characterized in that it is changed according to.