JP2018105646A - Film thickness distribution measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus capable of suppressing the vertical swing of a rotating substrate even if a load pressing a contact piece is changed without holding a central portion of a circular substrate with a rigid member, thereby setting a wide imaging range for measuring a film thickness measurement.SOLUTION: A film thickness distribution measuring apparatus 1 for measuring a film thickness distribution of a lubricant for lubricating contact portions between objects in an EHL state, includes: a circular substrate 2 with optical transparency; a rotating mechanism 4 for the circular substrate; a contact piece 3; a load imparting mechanism 5; a light source unit 7; an image pickup unit 8; a film thickness distribution measurement unit 12 for analyzing an interference fringe image picked up by the image pickup unit to measure a film thickness distribution of the lubricant; a supporting portion 61 disposed outside an outer peripheral portion of the circular substrate; and a substrate pressing portion 6 that is attached to the supporting portion and presses the outer peripheral portion of the circular substrate from up and down directions to suppress the vertical swing of the outer peripheral portion generated when the circular substrate rotates.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a film thickness distribution measuring apparatus for measuring a film thickness distribution of a lubricant at a contact portion of a rotating body or a sliding object rotating through a lubricant with respect to a rotating or reciprocating substrate.

  For example, in a bearing, a ball (one object) lubricated with lubricating oil and an outer ring or inner ring (the other object) are in line contact or point contact. At this time, the load concentrates on the contact portions of the objects, so that the objects are elastically deformed, and an elastic fluid lubrication state (EHL state: Elasto-hydrodynamic Lubrication) in which the lubricating oil becomes high pressure and high viscosity is obtained.

  As a conventional method for observing the EHL state of such a bearing, a disk-shaped disk and a steel ball are arranged so as to rotate or slide relative to each other, and the contact portion of the disk and the steel ball is lubricated with a lubricating oil. A technology that measures the film thickness of lubricant based on the wavelength of white stripes and the wavelength of black stripes by generating line-shaped interference fringes by irradiating the contact area with lubricating oil while scanning the line-shaped light Is known (for example, Patent Document 1).

  Also, in an oil film dielectric breakdown evaluation apparatus that examines the dielectric breakdown of an oil film by applying a voltage between two objects sandwiching the oil film, one object is a transparent body, and visible light is on the contact surface side with the other object. A technique is known in which an oil film thickness of a contact surface is measured by an optical interferometry in a state where a load is applied using an electrode that transmits light (for example, a transparent conductive film) (for example, Patent Document 2).

  Also, irradiate light with multiple wavelengths toward the transparent film, capture a color interference fringe image generated by the surface reflection light and back surface reflection light of the transparent film, and fit the interference fringe model to the image A technique is known in which film thicknesses at a plurality of points are collectively measured (that is, a film thickness distribution is measured without requiring calibration of the relationship between each color information and a film thickness value) (for example, Patent Documents) 3, Non-Patent Document 1). Further, Non-Patent Document 1 describes that a film thickness range of 8 μm can be expected by a combination of blue: 470 nm, green: 560 nm, and red: 600 nm, and a film thickness of 4 μm can be measured by an experiment using an actual sample. Yes.

JP 2007-327949 A JP 2008-241383 A JP 2013-145229 A

Kitagawa, Daigo, “Development of a wide-field thickness distribution measuring device for transparent films by interference color image analysis”, Journal of Precision Engineering, November 2013, Vol. 79, No. 11, pp. 1078-1082

  In the techniques of Patent Documents 1 and 2, in order to relatively rotate or slide a disk-shaped disk (circular substrate) and a steel ball (contact piece), a disk rotating shaft attached to the center of the circular substrate is used. The circular substrate is rotated by rotating.

  In order to bring the contact portion between the circular substrate and the contact piece into the EHL state, it is necessary to rotate the circular substrate at a high speed, and it is necessary to press the contact piece against the circular substrate with an arbitrary force. Therefore, it is necessary to press the central portion of the circular substrate from the upper surface side or the lower surface side with a robust member so that the rotating disk does not shake due to up and down movement.

  However, in order to make the central portion of the circular substrate robust, it is necessary to dispose a large member to some extent. Then, this member interferes with the imaging range for film thickness measurement, and there is a problem that the imaging range cannot be set wide.

  Therefore, the present invention can suppress the vertical swing of the rotating substrate even if the load for pressing the contact piece is changed without holding the central portion of the circular substrate with a robust member, and for film thickness measurement. An object of the present invention is to provide a device capable of setting a wide imaging range.

In order to solve the above problems, an aspect of the present invention is as follows.
A film thickness distribution measuring apparatus for measuring a film thickness distribution of a lubricant that lubricates a contact portion between objects in an EHL state,
A circular substrate with optical transparency;
A rotation mechanism for rotating the circular substrate;
A contact piece that contacts the circular substrate via a lubricant;
A load applying mechanism for applying a load by pressing the contact piece against the substrate side;
A light source unit that emits light of a predetermined wavelength toward the contact part of the substrate and the contact piece;
An imaging unit for imaging light reflected from the contact part of the substrate and the contact piece through the substrate;
A film thickness distribution measuring unit that acquires an interference fringe image of a contact portion of the circular substrate and the contact piece imaged by the imaging unit, analyzes the interference fringe image, and measures the film thickness distribution of the lubricant,
A support part arranged outside the outer peripheral part of the circular substrate, and an up-and-down swing of the outer peripheral part that occurs when the circular substrate rotates by pressing the outer peripheral part of the circular substrate from above and below by attaching to the support part. It is characterized by having a substrate pressing part that suppresses the above.

  According to this aspect, since the outer peripheral portion of the circular substrate is pressed in the vertical direction, the vertical swing of the rotating circular substrate can be suppressed even if the load pressing the contact piece is changed. Furthermore, it is not necessary to arrange a robust member at the center of the circular substrate, and interference with the imaging range for film thickness measurement can be avoided.

  Without holding the central part of the circular substrate with a robust member, even if the load that presses the contact piece is changed, the vertical swing of the rotating substrate can be suppressed, and imaging using a lens with a shallow depth of focus ( Acquisition of high-resolution images). In addition, it is possible to set a wide imaging range for film thickness measurement.

It is the schematic which shows the whole structure of an example of the form which embodies this invention. It is an image figure which shows an example of the interference color image input into a film thickness distribution measurement part. It is an image figure which shows an example after carrying out 3 color separation of the interference color image. It is an image figure which shows an example of an interference color image. It is an image figure which shows an example of the image which represented the measurement result of film thickness distribution by two-dimensional distribution. It is an image figure which shows an example of the image which represented the measurement result of film thickness distribution in three dimensions. It is an image figure which shows an example of the measurement result profile of the film thickness distribution of a X direction and a Y direction, the positional information on a thinnest part, and film thickness information. It is the schematic which shows the principal part of another form which embodies this invention.

  Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. In each figure, the horizontal direction is expressed as the x direction and the y direction, and the direction perpendicular to the xy plane (that is, the gravity direction) is expressed as the z direction. Also, the direction against gravity is expressed as up, and the direction in which gravity works is expressed as down.

  FIG. 1 is a schematic diagram showing an overall configuration of an example of a form embodying the present invention.

  The film thickness distribution measuring apparatus 1 according to the present invention measures the film thickness distribution of a lubricant that lubricates the contact portion between the EHL circular substrate 2 and the contact piece 3. Specifically, the film thickness distribution measuring apparatus 1 captures an interference color image and measures the film thickness distribution of the lubricant based on the interference color image. More specifically, the film thickness distribution measuring apparatus 1 includes a circular substrate 2, a contact piece 3, a contact piece rotating mechanism 3R, a rotating mechanism 4, a load applying mechanism 5, a substrate pressing unit 6, a light source unit 7, and an imaging unit. 8, a film thickness distribution measuring unit 9, a computer unit CN, a display unit DU, and the like.

  The circular substrate 2 is made of a material having optical transparency. Specifically, the circular substrate 2 can be exemplified by a transparent glass disc 20 that is flat in the xy direction and has a predetermined thickness in the z direction. More specifically, a metal thin film such as chromium (Cr) is formed on the lower surface of the disk 20, and the refractive index similar to that of a lubricant such as silicon oxide (SiO2) is further formed on the lower surface. The transparent film is formed.

  The contact piece 3 rotates while contacting the circular substrate 2 via a lubricant. Specifically, as the contact piece 3, a steel ball 30 which is a type of rotating body is illustrated. A shaft 31 is connected to the steel ball 30. The shaft 31 has a predetermined length in a direction parallel to the xy plane (the x direction in FIG. 1), and is connected to a contact piece rotating mechanism 3R described later.

  The steel ball 30 is in contact with the transparent film 22 on the lower surface of the disk 20 via a lubricant. The steel ball 30 is incorporated in a box-shaped holder 33 whose upper surface is open. The holder 33 is provided with a rotation support portion that rotatably supports the shaft 31 through the side surface. The upper part of the steel ball 30 protrudes above the open upper surface of the holder 33, and an oil pan (not shown) for storing a lubricant is provided below the steel ball 30. When the steel ball 30 incorporated in the holder 33 rotates, the lubricant accumulated in the oil pan moves upward due to its own viscosity, and the excess lubricant falls downward. Therefore, an appropriate amount of lubricant is supplied to the contact portion between the disk 20 and the steel ball 30.

  The contact piece rotating mechanism 3R rotates the contact piece 3 that is a rotating body. Specifically, the contact piece rotating mechanism 3R rotates or stops the steel ball 30 and the shaft 31 at a predetermined speed in the direction of the arrow 3v, or at a predetermined speed in the direction opposite to the arrow 3v. It is intended to rotate. More specifically, the contact piece rotating mechanism 3R includes a rotation motor 35 and a shaft 36 connected to the rotor of the rotation motor 35. The shaft 31 and the shaft 36 are connected via a coupling, a universal joint, or the like. It is connected. The rotary motor 35 is attached to the frame 1f via a connecting member 38.

  The rotation motor 35 is connected to a computer unit CN, which will be described in detail later, via a motor amplifier unit (not shown), and the rotation direction and rotation speed of the shaft 36 (that is, the steel ball 30 connected thereto) are appropriately controlled. Is done.

  The rotation mechanism 4 rotates the circular substrate 2. Specifically, the rotation mechanism 4 can be configured by a rotation motor 40, a roller 41, and the like.

  The rotary motor 40 rotates the disk 20 at a predetermined speed in a direction indicated by an arrow 4v with an axis perpendicular to the xy direction as a rotation center, or stops at a predetermined speed in a direction opposite to the arrow 4v. It is intended to rotate. More specifically, the rotary motor 40 includes a main body portion and a rotor (not shown) incorporated inside the main body portion, and a roller 41 is connected to the rotor via a shaft or the like.

  The roller 41 transmits the rotational force of the rotary motor 40 to the disk 20. Specifically, the roller 41 is composed of a cylindrical member in which a material having a large sliding frictional force such as rubber or flexible resin is arranged on the outer peripheral surface.

  The rotation motor 40 is mounted on the device frame 1f so that the outer peripheral surface of the roller 41 is always in contact with the outer peripheral portion of the disk 20. The rotary motor 40 is connected to a computer unit CN, which will be described in detail later, via a motor amplifier unit (not shown), and the rotational direction and rotational speed of the disc 20 are appropriately controlled.

  The load application mechanism 5 applies a load when the steel ball 30 is brought into contact with the disk 20. Specifically, the load application mechanism 5 pushes the steel ball 30 disposed below the disk 20 upward. More specifically, the load application mechanism 5 includes an actuator 50, a pressing load measuring unit (not shown), a pressing load control unit, and the like. The actuator 50 pushes up the steel ball 30 from the lower surface side of the disk 20 upward with a predetermined load. Specifically, the actuator 50 is such that the mover 51 moves up and down by air, hydraulic pressure, and electric power, and a holder 33 in which a steel ball 30 is incorporated is attached to the mover 51. In addition, the actuator 50 has a fixed-side main body attached to the device frame 1f, and is connected to a pressing load control unit described later.

  The pressing load measuring unit measures a load when the steel ball 30 is pressed against the disc 20. Specifically, the pressing load measuring unit includes a load cell (not shown) and an amplifier unit. The load cell is arranged between the mover 51 of the load applying mechanism 5 and the holder 33 in which the steel ball 30 is incorporated, and measures the amount of strain in the load cell caused by the load when the steel ball 30 is pressed against the disk 20. Then, a signal corresponding to the amount of distortion is output to the amplifier unit. When the signal output from the load cell is input, the amplifier unit converts the strain amount into a load value (or stress value), displays the load value, and sends signals and data corresponding to the load value to the computer CN or the pressing unit. It is configured to output to an external device such as a load control unit.

  The pressing load control unit controls the pressing load that presses the contact piece 3 against the circular substrate 2 side in the load applying mechanism 5. Specifically, the pressing load control unit inputs a signal corresponding to a load value or a stress value from the pressing load measurement unit, compares it with a preset reference value, and controls the actuator 50 of the load applying mechanism 5. And the load which presses the steel ball 30 against the disc 20 is controlled. More specifically, the pressing load control unit is configured by a dedicated control unit, and may input a reference value of the pressing load from the computer unit CN or output a current value of the pressing load to the computer unit CN. it can. Therefore, the pressing load can be automatically controlled, and a constant load can be continuously applied during the film thickness distribution measurement time.

  In addition, the rotational speed of the disc 20, the rotational speed of the steel ball 30, the pressing load by the actuator 60 of the load applying mechanism 5, and the like are set or assumed so as to reproduce the state in which the bearing is actually used. Set according to usage conditions. By doing so, the environmental condition of the contact part in the bearing which rotates in an EHL state can be set.

  The substrate pressing portion 6 suppresses the vertical deflection of the outer peripheral portion that occurs when the circular substrate 2 rotates. Specifically, the substrate pressing portion 6 includes a support portion 61 and a pair of upper and lower rollers 62.

  The support portion 61 is disposed outside the outer peripheral portion of the circular substrate 2 and is attached on the device frame 1f. Further, a pair of upper and lower rollers 62 are attached to the support portion 61.

  The pair of upper and lower rollers 62 presses the outer peripheral portion of the circular substrate 2 from the upper and lower directions, and is in contact with the upper surface Es side and the lower surface Eb side of the outer peripheral edge portion E of the circular plate 20 (that is, the circular plate 20 is pressed). And is rotated following the rotation of the disk 20.

  Specifically, a plurality of pairs of upper and lower rollers 62 are arranged so as to surround the outer periphery of the disk 20, and each of the pair of upper and lower rollers 62 has a rotation center (also referred to as a rotation axis) at the center of the disk 20. It is arranged to face. The pair of upper and lower rollers 62 are spaced apart from each other by the thickness of the disk 20.

  In the pair of upper and lower rollers 62, a portion that contacts the disk 20 (that is, a portion where the upper roller contacts the upper surface of the disk 20 and a portion where the lower roller contacts the lower surface of the disk 20). Each is called a contact part. And this contact part controls that the outer peripheral part of the disk 20 moves to an up-down direction, and suppresses the up-and-down swing of the disk 20. FIG.

  The support portion 61 and the pair of upper and lower rollers 62 are disposed at positions of 1 o'clock, 5 o'clock, and 10 o'clock (that is, three locations) as referred to, for example, on the dial of an analog clock (y direction) Is 12 o'clock and the x direction is 3 o'clock).

  Since the substrate pressing portion 6 has such a configuration, the vertical swing of the rotating disc 20 is changed even when the load pressing the steel ball 30 is changed in order to press the outer periphery of the disc 20 from the vertical direction. Can be suppressed.

  The light source unit 7 emits light of at least three types of wavelengths toward the contact portion between the circular substrate 2 and the contact piece 3. Specifically, the light source unit 7 includes an illumination unit 70 and an illumination power source 75.

  The illumination unit 70 emits light of at least three types of wavelengths necessary for capturing an interference color image. Specifically, the illumination unit 70 includes a white lamp (not shown), a three-wavelength band filter, an illumination power source, and the like. The white lamp emits light in a wide band (so-called broad wavelength band) including blue: 470 nm, green: 560 nm, and red: 600 nm. Specifically, a halogen lamp can be exemplified. The three-wavelength band filter 73 passes at least three types of wavelength components (here, red, green, and blue are exemplified) of the light emitted from the white lamp and attenuates other wavelength components. is there. More specifically, the three-wavelength band filter is a so-called three-wavelength bandpass filter in which a plurality of thin films are formed on the surface of a glass or quartz substrate. The illumination power supply supplies power necessary for light emission to the white lamp of the illumination unit.

  The imaging unit 8 captures light reflected from the contact portion between the circular substrate 2 and the contact piece 3 as an interference color image with the color camera 80 through the circular substrate 2. Specifically, the imaging unit 8 includes a color camera 80 and a lens unit 81. Here, the light reflected from the contact portion between the circular substrate 2 and the contact piece 3 includes light reflected at the interface between the circular substrate 20 and the metal thin film 21 (so-called surface reflected light), a lubricant, The light reflected at the interface with the steel ball 30 (so-called back surface reflected light) is synthesized.

  The color camera 80 outputs a video signal (analog signal) and video data (digital signal) corresponding to the captured color image to the outside, and includes a color filter 85 and an image sensor 86.

  The lens unit 81 forms an image of the contact portion between the circular substrate 2 and the contact piece 3 on the image sensor 86 of the color camera 80. In addition, the lens unit 81 in this embodiment also has a role of irradiating light emitted from the light source 7 toward the imaging target, and makes the illumination light the same as the imaging optical axis (that is, a coaxial tilting method). Can do. Specifically, the lens unit 81 includes a half mirror (not shown), an objective lens, and an imaging lens. Therefore, the lens unit 81 reflects the light emitted from the light source unit 7 with a half mirror, irradiates the measurement target region R of the film thickness as illumination light, and reflects it from the contact portion between the circular substrate 2 and the contact piece 3. Of the emitted light, the light passing through the objective lens and the half mirror can be imaged on the image sensor of the color camera 80 by the imaging lens. In addition to the fixed magnification method and the zoom method, the lens unit 81 may include a plurality of objective lenses having different observation magnifications, and the objective lens to be used may be switched by a revolver mechanism.

  The computer unit CN inputs and outputs signals and data, stores data, performs arithmetic processing on the input or stored data, inputs and stores images, image processing on these images, determination processing based on image processing, and image conversion Processing, determination results, image output after image processing, and the like are performed. Specifically, the computer unit CN includes an input unit, an information recording unit, a numerical calculation processing unit, an image processing unit, and an output unit. More specifically, the computer unit CN includes a computer (hardware) having an image processing function and an execution program (software) thereof. The computer unit CN includes information input devices such as a keyboard, a mouse, and a track pad, and is connected to a display unit DU described later. Further, the computer unit CN includes an image recording unit 11 and a film thickness distribution measuring unit 12.

  The interference color image captured by the image recording unit 11 and the imaging unit 8 is recorded. Specifically, the image recording unit 11 includes an information recording unit (for example, a magnetic recording medium such as a hard disk, a semiconductor memory, or the like) of the computer unit CN.

  The film thickness distribution measuring unit 12 acquires an interference color image recorded in the image recording unit 11, and performs color separation for each light of at least three wavelengths from color information of each point included in the interference color image. Value is calculated, the phase for each wavelength is calculated from the luminance value, a plurality of film thickness candidates are calculated from the phase for each wavelength, and the circular substrate 2 and the contact piece 3 are calculated from the calculated plurality of film thickness candidates. The thickness distribution of the lubricant at the contact portion is measured. Specifically, the film thickness distribution measuring unit 12 includes an image processing unit and a numerical calculation processing unit (hardware) of the computer unit CN and an execution program (software) thereof.

  Therefore, when the video signal (analog signal) or video data (digital signal) output from the imaging unit 8 is input, the computer unit CN performs predetermined image processing based on the execution program, or the image recording unit. 11, the image is stored in the image recording unit 11, the image is read from the image recording unit 11, and predetermined image processing or numerical calculation processing is performed in the film thickness distribution measuring unit 12. The film thickness at each point in the entire image (that is, the film thickness distribution) can be measured based on the estimation result.

Specifically, the film thickness distribution measurement unit 12 performs the wavelength estimation process by interference fringe model matching as described in Patent Document 3 on each point (each measurement point) in the image, The film thickness distribution is estimated and measured. More specifically, the film thickness distribution measuring unit 12 irradiates illumination light including monochromatic light having a plurality of wavelengths to a transparent film to be measured, and is generated by reflected light on the surface of the transparent film and reflected light on the back surface. N or more selected points are selected from the interference image, and the wavelength λ (j) of the wavelength number j is known to the interference luminance signal of the wavelength number j corresponding to the i point among the n selected points. , The average luminance a (j) of the wavelength number j, the interferometric modulation factor b (j), and the film thickness t (i) of the point i are all or part of the unknown parameters and the rest are the known parameters. The luminance g (i, j) of the wavelength number j corresponding to the following expression is g (i, j) = a (j) [1 + b (j) × cos {4πt (i) / λ (j)}]
By matching the interference fringe model expressed by the following formula, processing for obtaining an unknown parameter (that is, film thickness estimation / measurement calculation processing) is performed.

Further, for an arbitrary point k in the interference image, the average luminance a (j) and the interference modulation degree b (j) of the known wavelength number j obtained in claim 1 and the luminance g of each wavelength at the point k are obtained. From (k, j), the phase φ (k, j) of the wavelength number j at the point k is expressed by the following equation φ (k, j) = cos ⁻¹ [{g (k, j) / a (j) − 1} / b (j)]
And a process (so-called ACOS method) for obtaining the film thickness t (k) at the point k from the obtained plurality of phases.

  FIG. 2 is an image diagram illustrating an example of an interference color image input to the film thickness distribution measuring unit 12. FIG. 4 shows an interference color image when the disk 20 and the steel ball 30 are stationary. In addition, although the color information is originally included in the image drawing, it is substituted with the one expressed in black and white shading due to the restriction as an attached drawing (the same applies hereinafter).

  FIG. 3 is an image diagram illustrating an example after the interference color image is separated into three colors. FIGS. 3A, 3B, and 3C are image diagrams showing an example of an image after the color interference color image is separated into three colors and converted into a single color image of blue, green, and red. It is. Specifically, the film thickness distribution measuring unit 12 performs phase calculation processing from the luminance values of the blue, green, and red points of the color camera, thereby separating the color interference color image into three colors, and then blue / green. Convert each red color into a single color gray image, perform phase calculation by the above-mentioned ACOS method, and calculate a film thickness candidate. Then, for each point, the estimated film thickness is calculated from the film thickness candidates of each color by the matching method, and the film thickness distribution is calculated based on the estimated film thickness (that is, the film thickness estimation / measurement calculation process).

The display unit DU is also called an information display or a display monitor. When a video signal output from the computer unit CN is input, characters, graphic information, and the like are displayed corresponding to the video signal. Specifically, the display unit DU
1) The interference color image selected from the interference color images recorded in the image recording unit 11 2) An image representing the lubricant film thickness distribution measured by the film thickness distribution measurement unit 12 in a two-dimensional distribution 3) While displaying at least any one of the three-dimensional images of the lubricant film thickness distribution measured by the film thickness distribution measuring unit 12,
4) Position information and film thickness information of the thinnest film thickness recorded in the thinnest film thickness information recording unit are also displayed (that is, displayed at once).

  FIG. 4 is an image diagram showing an example of an image showing an example of an interference color image.

  FIG. 5 is an image diagram illustrating an example of an image in which the measurement result of the film thickness distribution is represented by a two-dimensional distribution.

  FIG. 6 is an image diagram illustrating an example of an image that three-dimensionally represents the measurement result of the film thickness distribution.

  FIG. 7 is an image diagram showing an example of the measurement result profile of the film thickness distribution in the X direction and the Y direction, the position information of the thinnest film thickness, and the film thickness information.

  Since the film thickness distribution measuring apparatus 1 according to the present invention has such a configuration, the circular substrate 2 and the contact piece 3 (in the above example, the disk 20 and the steel ball 30 which is a rotating body are illustrated). Regardless of the relative speed fluctuation, the film thickness distribution measurement of the lubricant that lubricates the contact portion between the substances in the EHL state can be performed in a wide range. At this time, even if the load pressing the contact piece 3 against the circular substrate 3 is changed, the vertical swing of the rotating circular substrate 2 can be suppressed, and imaging using a lens with a shallow depth of focus (acquisition of a high resolution image) ) Is possible. In addition, since it is not necessary to arrange a large reinforcing material around the center of the circular substrate 2, it is possible to set a wide imaging range for film thickness measurement.

[Another form]
In the above description, as the substrate pressing portion 6 according to the present invention, the support portion 61 and the pair of upper and lower rollers 62 attached to the support portion 61 so as to be spaced apart from each other by the thickness of the disc 20 are respectively the disc 20. The structure provided with two or more so that the outer periphery might be enclosed was shown. However, in embodying the present invention, the substrate pressing portion 6 is not limited to the above-described configuration, and may be in the form exemplified below.

  FIG. 8 is a schematic view showing a main part of another embodiment embodying the present invention. 8A to 8E show modified examples of the substrate pressing portion 6 according to the present invention.

  For example, a plurality of support portions 61 having a predetermined length in the vertical direction are arranged on the device frame 1f so as to surround the outer periphery of the disc 20, and the support portion 61 has a shape as shown below. The rollers 62a to 52e are attached so as to rotate around the z direction as a rotation center (also referred to as a rotation axis) without being displaced in the z direction.

  A roller 62a shown in FIG. 8A has a cylindrical outer peripheral surface having a predetermined length in the vertical direction, and has a stepped shape at the center (that is, the portion in contact with the outer peripheral portion of the disk 20) of the roller 62a. Grooves (also called dents or notches) are provided. The width of the stepped groove is set to be the same as or slightly smaller than that of the disk 20 (however, a range smaller than the depth of field of the image pickup unit 8). As described above, the respective support portions 61 and the rollers 62a are arranged on the apparatus frame 1f. Therefore, even if the disc 20 rotates, the outer peripheral portion of the disc 20 is restricted to move upward or downward (that is, up and down) from the groove, and the up and down deflection of the disc 20 is suppressed.

  A roller 62b shown in FIG. 8B has a cylindrical outer peripheral surface having a predetermined length in the vertical direction, and has a V-shape at the center of the roller 62b (that is, the portion in contact with the outer peripheral edge of the disk 20). A groove (also referred to as a dent or notch) is provided. The groove bent in the V shape is set to have a width, an angle, and a diameter that are in contact with the upper surface side and the lower surface side of the outer peripheral edge portion of the disc 20, and the outer peripheral edge portion of the disc 20 is inserted into this groove. As described above, the respective support portions 61 and the rollers 62b are arranged on the apparatus frame 1f. Therefore, even if the disk 20 rotates, the movement of the outer peripheral edge portion of the disk 20 upward or downward from the groove (that is, vertical deflection) is restricted, and vertical oscillation of the disk 20 is suppressed.

  A roller 62c shown in FIG. 8C has a substantially cylindrical outer peripheral surface having a predetermined length in the vertical direction, and is curved at the center portion of the roller 62c (that is, the portion in contact with the outer peripheral edge portion of the disk 20). A constricted part (also referred to as a waist part) is provided. In addition, this curved constriction part is set to the curvature rate and diameter which contact | abut to the upper surface side and lower surface side of the outer periphery edge part of the disc 20, and the outer periphery edge part of the disc 20 covers this constriction part, The respective support portions 61 and the rollers 62c are arranged on the device frame 1f. Therefore, even if the disk 20 rotates, the movement of the outer peripheral edge portion of the disk 20 upward or downward from the constricted portion (that is, vertical swing) is restricted, and the vertical swing of the disk 20 is suppressed.

  A roller 62d shown in FIG. 8D includes a substantially cylindrical bent outer peripheral surface having a predetermined length in the vertical direction, and a central portion of the roller 62d (that is, a portion in contact with the outer peripheral edge portion of the disk 20). Has a constricted portion with a smaller diameter. The bent outer peripheral surface and the constricted portion are set to a bending angle and a diameter that come into contact with the upper surface side and the lower surface side of the outer peripheral edge portion of the disc 20, and the outer peripheral edge portion of the disc 20 is attached to the constricted portion. As described above, the respective support portions 61 and the rollers 62d are arranged on the apparatus frame 1f. Therefore, even if the disk 20 rotates, the movement of the outer peripheral edge portion of the disk 20 upward or downward from the constricted portion (that is, vertical swing) is restricted, and the vertical swing of the disk 20 is suppressed.

  A roller 62e shown in FIG. 8 (e) has a substantially cylindrical curved outer peripheral surface having a predetermined length in the vertical direction, and a central portion of the roller 62e (that is, a portion in contact with the outer peripheral edge portion of the disk 20). Has a constricted portion with a smaller diameter. The curved outer peripheral surface and the constricted portion are set to have a curvature and a diameter that are in contact with the upper surface side and the lower surface side of the outer peripheral edge portion of the disc 20, and the outer peripheral edge portion of the disc 20 is attached to the constricted portion. As described above, the respective support portions 61 and the rollers 62e are arranged on the apparatus frame 1f. Therefore, even if the disk 20 rotates, the movement of the outer peripheral edge portion of the disk 20 upward or downward from the constricted portion (that is, vertical swing) is restricted, and the vertical swing of the disk 20 is suppressed.

  That is, the substrate pressing portion 6 according to the present invention includes a roller having a curved or bent cylindrical contact surface that contacts the upper surface side and the lower surface side of the outer peripheral edge portion of the circular substrate 2. The imaging range is expanded to the vicinity of the outermost periphery of the substrate while suppressing the vertical swing of the rotating circular substrate 2, and the lubricant film thickness can be measured in the region where the contact piece 2 rotates at a higher speed.

  In the above description, a configuration in which the pair of upper and lower rollers 62 and rollers 62a to 62e constituting the substrate pressing portion 6 rotate following the rotation of the disk 20 is shown. Such a configuration is preferable because wear of a portion where the disk 20 and the roller are in contact with each other can be suppressed to a minimum while reliably suppressing vertical deflection of the outer peripheral edge portion of the disk 20. However, in realizing the present invention, it is not an essential component that the rollers 62, 52a to e can rotate, and one or both of the upper and lower pair of rollers 62 and the rollers 62a to 62e are fixed. In addition, a configuration may be provided that includes a member that presses in the vertical direction while sliding with respect to the disc 20 (that is, a sliding pressing member). By doing so, vertical deflection of the outer peripheral edge portion of the disk 20 can be suppressed. In this case, it is preferable that the surface of the sliding pressing member is made of a material or shape with little friction, or a lubricant is applied to the sliding portion with the disk 20.

  In the above description, the substrate holding portion 6 is shown at an example where it is arranged at the 1 o'clock, 5 o'clock, and 10 o'clock positions (that is, 3 locations), for example, on the dial of an analog clock. You may arrange | position to the position and may arrange | position four or more places, and should just arrange | position so that the place where the space | interval separated most may become shorter than the half length of the outer periphery of the disc 20. FIG.

  The pair of upper and lower rollers 62 and rollers 62a to 62e constituting the substrate pressing part 6 are preferably made of metal or hard resin. By doing so, the deformation | transformation at the time of pressing the disk 20 from an up-down direction hardly arises, and the up-and-down swing of the outer peripheral part of the disk 20 can be suppressed reliably.

  However, the rollers 62 and 62a to 62e may be formed of an elastic resin or the like on the outer peripheral surface or the main body in consideration of the deformation amount of the outer peripheral surface and the depth of field of the imaging unit 8.

[Another form]
In the above description, as the film thickness distribution measuring apparatus 1 according to the present invention, the rotation mechanism 4 that rotates the circular substrate 2 and the substrate pressing portion 6 that presses the vertical swing of the circular substrate 2 are provided separately. showed that. However, when the present invention is embodied, it is not an essential condition that they are provided independently, and the circular substrate 2 is rotated by rotating a part or all of the rollers constituting the substrate pressing portion 6. The structure (that is, the rotation mechanism 4 and the board | substrate holding | suppressing part 6 are combined) may be used. Doing so is preferable because the device configuration is simplified.

[Modification of rotation mechanism]
The rotation mechanism 4 according to the present invention is not limited to the configuration as described above, and may be a configuration attached to the center of the disk 20. Even in this case, since the substrate pressing portion 6 is disposed on the outer periphery of the disc 20, it is not necessary to fix the central portion of the disc 20 with a robust member or structure.

[Modification of contact piece]
In the above description, the contact piece 3 is an example of a steel ball 30 that is a type of rotating body in order to reproduce the contact portion in the ball bearing. However, the contact piece 3 is not limited to a steel sphere as a rotating body, and may be other materials (for example, aluminum, ceramic, resin, etc.), and have other shapes (for example, a cylinder, a cone, etc.). Also good. Further, the contact piece 3 may be constituted by a sliding object (that is, a non-rotating object) such as a flat plate piece as well as a rotating body. And a flat piece can be suitably selected from arbitrary materials, such as steel, aluminum, a ceramic, and resin.

  Moreover, in the above-mentioned, the steel ball 30 which is a kind of rotary body is provided as the contact piece 3, and the example using the contact piece rotation mechanism 3R is shown. With such a configuration, at least one of the rotation speed of the rotation mechanism 4 and the rotation speed of the contact piece rotation mechanism 3R is controlled, and the rotation speed between the circular substrate 2 and the steel ball 30 that is the rotating body. It is possible to set the “slip rate” resulting from the difference between the two. Therefore, it is preferable that the lubricant film thickness distribution can be measured by setting an arbitrary slip rate.

  However, the contact piece rotating mechanism 3 </ b> R is not an essential component for embodying the present invention, and may be configured to omit this, and the rotatable steel ball 30 follows the rotation of the disk 20. It is good also as a structure rotated so that it may do, or a structure which slides while contacting the non-rotating contact piece in contact with the disc 20 (that is, sliding). By doing so, it becomes possible to measure the film thickness of the lubricant in the EHL state in the steel ball that rotates following and the sliding contact piece.

[Modifications by load application mechanism]
In the above description, the configuration (so-called automatic control system) including the actuator 60 for adjusting the load for pressing the contact piece 3 against the circular substrate 2 and the pressing load control unit for controlling the pressing load is illustrated. However, the pressing load control unit may be configured to be incorporated in a part of the computer unit CN instead of the dedicated control unit as described above.

  In addition, the pressing load control unit is not an essential component for embodying the present invention, omitting this, and using an elastic body such as a spring or rubber instead of an automatic control system, the position can be changed by an external signal. The structure (what is called a semiautomatic operation system) provided with the actuator 60 which can be used may be sufficient. Alternatively, the actuator 60 may be omitted, and the contact piece 3 may be adjusted in the z direction by shim adjustment, fixing screw position adjustment, rotation adjustment, or the like to change the pressing load (so-called manual adjustment method).

[Modification of substrate]
Further, in the above description, the circular substrate 2 is a flat glass disk 20, and a metal thin film such as chrome and a transparent film such as silicon oxide are formed on the lower surface thereof, and a contact portion with the contact piece 3. An example in which is a flat surface is shown. However, the shape of the contact portion of the circular substrate 2 is not limited to such a shape, and may be configured by a curved surface, or may have a flat surface or a curved surface formed with a groove. The shape of the contact portion may be a shape that reproduces or models the shape of a bearing or a sliding object that is desired to measure the film thickness distribution of the lubricant. The material of the circular substrate 2 is not limited to glass, but may be other materials such as sapphire, silicon, and resin.

  In addition, the metal thin film on the lower surface of the circular substrate 2 is not limited to the above-described chromium, but may be a thin film made of aluminum, copper, silver, gold, or the like (also referred to as coating). In practicing the present invention, the metal thin film is for generating so-called surface reflected light for obtaining an interference color image. Therefore, the metal thin film may not be formed as long as reflected light is obtained from the interface between the circular substrate 2 and the lubricant.

  Further, the transparent film 22 on the lower surface of the circular substrate 2 is not limited to the above-described silicon oxide, but may be a film formed of a transparent material close to the refractive index of the lubricant. Note that the transparent film is processed so that the apparent film thickness is measured to increase the measurement resolution and the film thickness of the transparent film is subtracted later, even if the lubricant film thickness is thin. Is to do. Therefore, the transparent film on the lower surface of the circular substrate 2 may not be formed if the thickness of the lubricant can provide a desired measurement resolution.

[Modification of light source section]
The white lamp 70 constituting the light source unit 7 is not limited to the halogen lamp described above, and may be a metal halide lamp, a xenon lamp, a mercury lamp, a white LED, or the like.

  The three-wavelength band filter 73 constituting the light source unit 7 is not limited to the configuration arranged between the white lamp 70 and the half mirror 82 as described above, but between the objective lens 83 and the circular substrate 2, and the half mirror 82. And the imaging lens 84, or between the imaging lens 84 and the imaging camera 80, for example.

  The light source unit 7 is not limited to the configuration including the white lamp 70, the reflection plate 71, and the three-wavelength band filter 73 as described above, but the LED that emits red light, the LED that emits green light, and the light that emits blue light. It is good also as a structure provided with the light emission unit provided with LED to perform. In this case, one or more LEDs of each color are provided, and the illumination power supply is configured to supply a predetermined DC voltage and current to each LED. Alternatively, instead of the LED that emits light of each color, a laser diode that emits light of each color or a laser diode that emits light of three wavelengths simultaneously and a power source that drives the laser diode may be provided.

  In the above description, the light source unit 7 is configured to irradiate light having three types of wavelengths of blue: 470 nm, green: 560 nm, and red: 600 nm. However, the light source unit according to the present invention is not limited to such a configuration, and a part or all of the light source unit may be replaced with light of other wavelengths. In this case, examples of light of other wavelengths emitted from the light source unit include near infrared light, orange light, and blue-green light. Further, the wavelengths of light emitted from the light source unit 7 may be four types in total, or may be more types.

[Other variations]
Moreover, in the above, the structure provided with the display part DU in the film thickness distribution measuring apparatus 1 was illustrated. However, the display unit DU is not an essential component for embodying the present invention, and may be configured without this. In addition, the film thickness distribution measuring apparatus according to the present invention may be configured to output data including the result of measuring the film thickness distribution to an external apparatus or device regardless of whether or not the display unit DU is provided. good.

DESCRIPTION OF SYMBOLS 1 Thickness distribution measuring apparatus 2 Circular substrate 3 Contact piece 3R Contact piece rotation mechanism 4 Rotation mechanism 5 Load application mechanism 6 Substrate pressing part 7 Light source part 8 Imaging part CN Computer part DU display part 11 Image recording part 12 Film thickness distribution Measurement unit R Film thickness measurement target area 1f Device frame 2v Arrow (substrate movement direction, disk rotation direction)
3v arrow (moving direction of substrate, rotating direction of disc)
4v arrow (moving direction of contact piece, rotating direction of rotating body)
20 disc 30 steel ball (contact piece / one type of rotating body)
DESCRIPTION OF SYMBOLS 31 Shaft 33 Holder 35 Rotation motor 36 Shaft 40 Rotation motor 41 Roller 50 Actuator 51 Movable element 61 Support part 62 Roller 63a-e Contact part 70 Illumination unit (halogen lamp)
75 Power supply for illumination 80 Imaging camera 81 Lens unit

Claims (3)

A film thickness distribution measuring apparatus for measuring a film thickness distribution of a lubricant that lubricates a contact portion between objects in an EHL state,
A circular substrate with optical transparency;
A rotating mechanism for rotating the circular substrate;
A contact piece that contacts the circular substrate via the lubricant;
A load applying mechanism that applies a load by pressing the contact piece against the substrate;
A light source unit that emits light of a predetermined wavelength toward a contact portion of the substrate and the contact piece;
An imaging unit for imaging light reflected from the contact part of the substrate and the contact piece through the substrate;
A film thickness distribution measuring unit that acquires an interference fringe image of a contact portion between the circular substrate and the contact piece imaged by the imaging unit, and analyzes the interference fringe image to measure the film thickness distribution of the lubricant. Prepared,
A support portion disposed outside the outer peripheral portion of the circular substrate, and an outer peripheral portion that is attached to the support portion and presses the outer peripheral portion of the circular substrate from above and below, and is generated when the circular substrate rotates. A film thickness distribution measuring apparatus comprising a substrate pressing portion that suppresses vertical deflection. The said board | substrate holding | suppressing part was equipped with the roller which has the curved or curved cylindrical contact surface which contact | abuts to the upper surface side and lower surface side of the outer periphery edge part of the said circular board | substrate. Film thickness distribution measuring device.   The film thickness distribution measuring apparatus according to claim 1, wherein the rotation mechanism rotates the substrate by rotating the substrate pressing portion.

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