JP2017044587A - Film thickness distribution measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device that can conduct a film thickness distribution measurement of a lubricant lubricating a contact part among substances in an EHL state over a wide range regardless of presence or absence of a change in relative velocity between a substrate and rotor.SOLUTION: A film thickness distribution measurement device for a lubricant lubricating a contact part of objects in an EHL state comprises: a substrate that is provided with a light transmission property; a contact piece that contacts with the substrate via the lubricant; a movement mechanism that causes the substrate and the contact piece to relatively move; a load imparting mechanism; a light source; an interference color imaging unit; and a computer unit. The computer unit includes: an image recording unit that records an interference color image photographed by the interference color imaging unit; and a film thickness distribution estimation unit that subjects to a color separation the selected interference color for each light of at least three kinds of wavelengths from color information on each point to be included in the selected interference color image of the interference color images recorded in the image recording unit to calculate a luminance value, phase for each wavelength and a plurality of film thickness candidates, and estimates a film thickness distribution of the lubricant at the contact part between the substrate and the contact piece from the plurality of calculated film thickness candidates.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).

  In addition, a reflective film and a spacer film are sequentially formed, a light-transmitting substrate that contacts the sample with the spacer film, irradiation means for irradiating the light-transmitting substrate with white light from the opposite side of the spacer film, and reflected light of white light An interference image is obtained using a film thickness measuring device having a light receiving means for receiving light and a color information obtaining means for obtaining color information from reflected light, and the hue information is obtained by converting the color information into an HSV color space, A technique for visualizing a true contact portion corresponding to a gap thickness or zero film thickness based on a calibration result with a gap thickness between two surfaces is known (for example, Patent Document 2).

  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 3).

  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) 4, 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 2008-20318 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

  However, in the technique of Patent Document 1, since the film thickness distribution of the surface is measured by line scanning, the film thickness distribution does not change over time (for example, rotating or sliding at a constant speed). However, measurement was not possible.

  On the other hand, in the technique of Patent Document 2, it is possible to measure the two-dimensional distribution of the film thickness, but it is necessary to calibrate the relationship between each color information and the film thickness value. It varies depending on many factors such as the surface. Furthermore, although the color information (BGR value) is converted into a hue, there is a problem that the film thickness measurement range is limited because the hue is a period of about 260 nm in film thickness.

  On the other hand, in the technique of Patent Document 3, a two-color light source obtained by superimposing two colors of monochromatic light having different wavelengths of 555 nm (green) and 630 nm (red), and a gap in which the relationship between the actual oil film thickness and color is known in advance. The film thickness is measured from the color of the optical interference image on the basis of the relational data verified using. Therefore, as in Patent Document 2, it is necessary to calibrate the relationship between each color information and the film thickness value.

  On the other hand, Patent Document 4 describes that it can be applied to on-line measurement of the film thickness of a film sheet that runs continuously in a film manufacturing process, and Non-Patent Document 1 describes a film of a silicon oxide film on a silicon wafer. Although it is described that the thickness, the air gap of the Newton ring plate, and the film thickness of the soap film can be measured, there is no mention of a specific means for measuring the film thickness distribution of the lubricant in the EHL state such as a bearing. .

  Therefore, the present invention has an object to provide an apparatus capable of measuring transient film thickness fluctuation and film thickness distribution of a lubricant that lubricates a contact portion between substances in an EHL state without calibration in a wide film thickness range. To do.

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 substrate with optical transparency;
A contact piece that contacts the substrate via a lubricant;
A moving mechanism for relatively moving the substrate and the contact piece;
A load applying mechanism for applying a load by pressing the contact piece on the substrate side;
A light source that emits light of at least three wavelengths toward the contact portion of the substrate and the contact piece;
An interference color imaging unit that images light reflected from the contact portion of the substrate and the contact piece as an interference color image with a color camera through the substrate;
It has a computer part,
In the computer part,
An image recording unit for recording an interference color image captured by the interference color imaging unit;
Among the interference color images recorded in the image recording unit, the luminance value is calculated by color-separating at least three types of light from the color information of each point included in the selected interference color image, and the luminance value From the phase for each wavelength, a plurality of film thickness candidates are calculated, and from the calculated plurality of film thickness candidates, the lubricant film thickness distribution at the contact portion between the substrate and the contact piece is calculated. A film thickness distribution estimation unit for estimation is provided.

  According to this aspect, since the two-dimensional distribution of the lubricant film thickness can be measured at a high speed, a transitional film thickness distribution change (for example, acceleration / deceleration evaluation or fracture process evaluation) can be performed. In addition, since calibration is performed from the interference image obtained by imaging the target substrate by the wide-area model fitting method (so-called self-calibration is performed), it is not necessary to calibrate the relationship between each color information and the film thickness value. -If the three wavelengths of red are used, the film thickness distribution can be measured in a wide film thickness range of about 4 to 8 μm.

  Transient film thickness fluctuations and film thickness distributions of lubricants that lubricate contact portions between substances in the EHL state can be measured without calibration over a wide film thickness range.

It is the schematic which shows the whole structure of an example of the form which embodies this invention. It is the elements on larger scale which expanded and showed a part of example of the form which embodies the present invention. It is a functional block diagram which shows the connection of each apparatus in 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 estimation 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.

  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.
FIG. 2 is a partially enlarged view showing an enlarged part of an example embodying the present invention.
FIG. 3 is a functional block diagram showing the connection of each device in an example embodying the present invention.

  The film thickness distribution measuring apparatus 1 according to the present invention measures the film thickness distribution of the lubricant LB that lubricates the contact portion SP of the substrate 2 and the contact piece 3 in the EHL state. Specifically, the film thickness distribution measuring apparatus 1 captures an interference color image and measures the film thickness distribution of the lubricant LB based on the interference color image. More specifically, the film thickness distribution measuring apparatus 1 includes a substrate 2, a contact piece 3, a moving mechanism 4, a rotating body rotating mechanism 5, a load applying mechanism 6, a light source unit 7, an interference color imaging unit 8, and a computer unit 9. The display unit 10 and the like are provided.

  The board | substrate 2 is comprised with the material provided with the light transmittance. Specifically, the 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 21 such as chrome (Cr) is formed on the lower surface of the disc 20, and further on the lower surface thereof is approximately the same as the lubricant LB such as silicon oxide (SiO 2). A transparent film 22 having a refractive index is formed.

  The contact piece 3 rotates while contacting the substrate 2 via the lubricant LB. 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 (x direction in FIG. 1), and is connected to a rotating body rotating mechanism 5 described later.

  The steel ball 30 is in contact with the transparent film 22 on the lower surface of the disk 20 through the lubricant LB. An oil pan P for storing the lubricant LB is provided below the steel ball 30. When the steel ball 30 rotates, the lubricant LB accumulated in the oil pan P moves upward due to its own viscosity, and the excess lubricant falls downward. Therefore, an appropriate amount of lubricant LB is supplied to the contact portion SP between the disk 20 and the steel ball 30.

  The moving mechanism 4 moves the substrate 2 and the contact piece 3 relative to each other. Specifically, the moving mechanism 4 can be configured by a rotary motor 40. The rotary motor 40 rotates the disk 20 at a predetermined speed in a direction indicated by an arrow 2d 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 2d. 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 the disk 20 and the rotor are connected by a connecting member 41. The rotation motor 40 is connected to a computer unit 9 described later in detail through a motor amplifier unit (not shown), and the rotation direction and rotation speed of the disk 20 are appropriately controlled.

The rotating body rotating mechanism 5 rotates a steel ball 30 that is a rotating body. Specifically, the rotating body rotating mechanism 5 rotates or stops the steel ball 30 and the shaft 31 at a predetermined speed in the direction of the arrow 3d, or rotates at a predetermined speed in the direction opposite to the arrow 3d. It is something to be made.
More specifically, the rotating body rotating mechanism 5 includes a rotating motor 50 and a shaft 51 connected to the rotor of the rotating motor 50.

  The rotation motor 50 is connected to a computer unit 9 described later in detail through a motor amplifier unit (not shown), and the rotation direction and rotation speed of the shaft 51 are appropriately controlled.

  The load applying mechanism 6 applies a load when the steel ball 30 is brought into contact with the disk 20. Specifically, the load application mechanism 6 pushes the steel ball 30 disposed below the disk 20 upward. More specifically, the load application mechanism 6 includes an actuator 60 and a holder 63. The actuator 60 is such that the movable element 61 moves up and down by air, hydraulic pressure, and electric power. The main body of the actuator 60 is attached to the apparatus frame 1 f, and the holder 63 is attached to the movable element 61. The actuator 60 is connected to a pressing load control unit 17 described later.

  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 6, and the like are set or assumed 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 light source unit 7 emits light L1 of at least three types of wavelengths toward the contact portion SP of the 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 70, a reflection plate 71, and a three-wavelength band filter 73. The white lamp 70 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 reflection plate 71 reflects the visible light emitted from the white lamp 70 and increases the amount of the light L1 that is irradiated to the outside. 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 70 and attenuates other wavelength components. It is. More specifically, the three-wavelength band filter 73 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 source 75 supplies power necessary for light emission to the white lamp 70 of the illumination unit 70.

  The interference color imaging unit 8 captures the light L3 reflected from the contact portion SP of the substrate 2 and the contact piece 3 as an interference color image with the color camera 80 through the substrate 2. Specifically, the interference color imaging unit 8 includes a color camera 80 and a lens unit 81. The light L3 reflected from the contact portion SP between the substrate 2 and the contact piece 3 referred to here is light reflected at the interface between the substrate 20 and the metal thin film 21 (so-called surface reflected light), and the lubricant LB. And the light reflected at the interface between the steel ball 30 (so-called back surface reflected light).

  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 SP between the 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 82, an objective lens 83, and an imaging lens 84. Therefore, the lens unit 81 reflects the light L1 irradiated from the light source unit 7 by the half mirror 82 and irradiates the measurement target region R of the film thickness as the illumination light L2, so that the contact portion between the substrate 2 and the contact piece 3 Of the light L3 reflected from the SP, the light L4 that has passed through the objective lens 83 and the half mirror 82 can be imaged on the image sensor 86 of the color camera 80 by the imaging lens 84.

  The computer unit 9 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 9 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 9 includes a computer (hardware) having an image processing function and an execution program (software) thereof. The computer unit 9 includes information input devices such as a keyboard, a mouse, and a track pad, and is connected to a display unit 10 described later.

  The computer unit 9 includes an image recording unit 11 and a film thickness distribution estimation unit 12. Further, the computer unit 9 includes a thinnest film thickness information recording unit 13, a traction coefficient calculation unit 15, and a slip rate control unit 16.

  The interference color image captured by the image recording unit 11 and the interference color 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 9.

  The film thickness distribution estimation unit 12 performs color separation for each light of at least three wavelengths from the color information of each point included in the selected interference color image among the interference color images recorded in the image recording unit 11. A luminance value is calculated, a 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 substrate 2 and the contact piece 3 are calculated from the calculated plurality of film thickness candidates. The film thickness distribution of the lubricant LB at the contact portion SP is estimated. Specifically, the film thickness distribution estimation unit 12 includes an image processing unit and a numerical calculation processing unit (hardware) of the computer unit 9 and an execution program (software) thereof.

  Therefore, when the video signal (analog signal) or video data (digital signal) output from the interference color imaging unit 8 is input, the computer unit 9 performs predetermined image processing based on the execution program, The film thickness distribution can be estimated by storing an image in the recording unit 11, reading an image from the image recording unit 11, or performing predetermined image processing or numerical calculation processing in the film thickness distribution estimating unit 12. it can.

Specifically, the film thickness distribution estimation unit 12 estimates the film thickness distribution by performing wavelength estimation processing based on interference fringe model matching described in Patent Document 4 on each point in the image. To do. More specifically, the film thickness distribution estimation unit 12
Illumination light including monochromatic light of multiple wavelengths is irradiated onto the transparent film to be measured, and n or more selected points are selected from the interference image generated by the reflected light on the surface and the back surface of the transparent film 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, and the average luminance a (j) of the wavelength number j is interferometric modulated. The brightness g (i, j) of the wavelength number j corresponding to the point i with the degree b (j) and the film thickness t (i) of the point i all or part of them as unknown parameters and the rest as known parameters G (i, j) = a (j) [1 + b (j) × cos {4πt (i) / λ (j)}]
By matching the interference fringe model expressed by the following, processing for obtaining an unknown parameter (that is, film thickness estimation 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. 4 is an image diagram illustrating an example of an interference color image input to the film thickness distribution estimation 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. 5 is an image diagram illustrating an example after the interference color image is separated into three colors. FIGS. 5A, 5B, and 5C 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 estimation unit 12 separates the color interference color image into three colors by performing phase calculation processing from the luminance values of the blue, green, and red points of the color camera, and the 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. For each point, the estimated film thickness is calculated from the film thickness candidates for each color by the matching method (that is, the film thickness estimation calculation process).

  The thinnest film thickness information recording unit 13 records the position and film thickness of the thinnest film thickness in the film thickness distribution of the lubricant LB at the contact portion SP of the substrate 2 and the contact piece 3. . Specifically, the thinnest film thickness information recording unit 13 is composed of an information recording unit of the computer unit 9.

  Furthermore, in this embodiment, the structure provided with the pressing load measurement part 65, the torque measurement part 14, and the traction coefficient calculation part 15 is illustrated.

  The pressing load measuring unit 65 measures a load when the steel ball 30 is pressed against the disk 20. Specifically, the pressing load measuring unit 65 includes a load cell and an amplifier unit (not shown). The load cell is disposed between the mover 61 of the load applying mechanism 6 and the holder 63, measures the amount of strain in the load cell caused by the load when the steel ball 30 is pressed against the disk 20, and corresponds to this strain amount. This signal 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 outputs signals and data corresponding to the load value to the computer 9 or later. Output to an external device such as the pressing load control unit 17.

  The torque measuring unit 14 measures the transmission torque T during rotation of the steel ball 30 that is a rotating body. Specifically, the torque measuring unit 14 exemplifies a configuration including a torque meter 55 disposed between the shaft 31 connected to the steel ball 30 and the shaft 51 of the rotating body rotating mechanism 5. The torque meter 55 includes a main body portion 56 and a shaft 57, and measures a transmission torque T acting on the shaft 57. Specifically, since the shaft 57 is twisted as it rotates, the torque meter 55 measures the amount of distortion of the shaft 57 caused by this twist, converts it into a transmission torque T that transmits the shaft 57, and outputs it. . One end of the shaft 57 is connected to the shaft 51 via the coupling 52 and the other end is connected to the shaft 31 via the coupling 53, and no slip occurs. Therefore, the torque meter 55 can measure the transmission torque during rotation of the steel ball 30 that is a rotating body by measuring the transmission torque T of the shaft 57. Further, the torque meter 55 can output a signal and data corresponding to the measured transmission torque T to the computer 9 directly or via another device.

  The traction coefficient calculator 15 calculates the traction coefficient μ. The traction coefficient μ referred to here is also called a drive coefficient, and represents the degree of friction generated between the disk 20 and the steel ball 30 as a rotating body in a non-dimensional manner. Specifically, the traction coefficient calculation unit 15 transmits the transmission torque T during the rotation of the steel ball 30 (that is, the transmission torque transmitted through the shaft 57 measured by the torque measurement unit 14) and the steel ball 30 that is a rotating body. The traction coefficient μ is calculated on the basis of the rotation radius RB and the load Wb for pressing the steel ball 30 as the rotating body. Note that the equation for calculating the traction coefficient μ can be obtained by Equation (1). More specifically, the traction coefficient calculation unit 15 includes a numerical calculation processing unit (hardware) of the computer unit 9 and an execution program (software) thereof.

  The slip ratio control unit 16 controls the slip ratio between the substrate 2 and the rotating body by controlling at least one of the moving speed of the moving mechanism 4 and the rotating speed of the rotating body rotating mechanism 5. Specifically, the rotation speed of the disk 20 corresponding to the movement speed of the moving mechanism 4 is the number of rotations per unit time of the disk 20 and the position where the steel ball 30 contacts from the rotation center of the disk 20. Calculate from distance. On the other hand, the rotation speed of the rotating body rotating mechanism 5 is determined by the number of rotations per unit time of the shaft 51 connected to the steel ball 30 and the distance from the rotation center of the steel ball 30 to the place where the steel ball 30 contacts (that is, , From the radius of rotation RB of the steel ball. Then, the rotational speed of the disc 20 and the rotational speed of the shaft 51 are controlled so as to achieve a desired slip rate. At this time, if the disk 20 and the steel ball 30 are rotating at the same speed, the slip rate is 0%, and if either one is stationary, the slip rate is 100%.

  The pressing load control unit 17 controls the pressing load that presses the contact piece 3 against the substrate 2 side in the load applying mechanism 5. Specifically, the pressing load control unit 17 inputs a signal corresponding to a load value or a stress value from the pressing load measurement unit 65, compares it with a preset reference value, and compares the actuator 60 of the load applying mechanism 6 with the actuator 60. To control the load that presses the steel ball 30 against the disk 20. More specifically, the pressing load control unit 17 is configured by a dedicated control unit, and inputs a reference value of the pressing load from the computer unit 9 or outputs a current value of the pressing load to the computer unit 9. Can do. Therefore, the pressing load can be automatically controlled, and a constant load can be continuously applied during the film thickness distribution measurement time.

The display unit 10 is also called an information display or a display monitor. When a video signal output from the computer unit 9 is input, characters, graphic information, and the like are displayed corresponding to the video signal. Specifically, the display unit 10
1) The interference color image selected from the interference color images recorded in the image recording unit 11 2) The image showing the film thickness distribution of the lubricant LB estimated by the film thickness distribution estimation unit 12 as a two-dimensional distribution 3 ) While displaying at least one of the three-dimensional images of the film thickness distribution of the lubricant LB estimated by the film thickness distribution estimation unit 12,
4) The position information and film thickness information of the thinnest film thickness recorded in the thinnest film thickness information recording unit 13 are also displayed together (that is, displayed at once).

  FIG. 6 is an image diagram showing an example of an image showing an example of an interference color image.

  FIG. 7 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. 8 is an image diagram illustrating an example of an image that three-dimensionally represents the measurement result of the film thickness distribution.

  FIG. 9 is an image diagram illustrating an example of a measurement result profile of film thickness distribution in the X direction and the Y direction, position information of the thinnest film thickness, and film thickness information.

  Since the film thickness distribution measuring apparatus 1 according to the present invention has such a configuration, the relative relationship between the substrate 2 and the contact piece 3 (in the above example, the disk 20 and the steel ball 30 which is a rotating body is illustrated). Regardless of the speed fluctuation, the film thickness distribution of the lubricant LB that lubricates the contact portion SP between the substances in the EHL state can be measured in a wide range. At this time, the film thickness distribution is measured in a wide film thickness range of about 4 μm to 8 μm by irradiating light including three wavelengths of red, green, and blue from the light source unit 7. can do.

[Another form]
Further, in realizing the present invention, the film thickness distribution measuring apparatus is not limited to the above-described configuration, and may be in the form exemplified below.

  For example, the display unit 10 described above may display the number of rotations of the disk 20, the number of rotations of the steel ball 30 as a rotating body, pressing load, rotational torque, traction coefficient, slip rate, and the like as necessary. Alternatively, the operator may operate the information input device of the computer unit 9 to read an interference color image at an arbitrary time from the image recording unit 11 and display the interference color image on the display unit 10. Furthermore, the film thickness distribution measuring apparatus 1 may display the film thickness distribution measurement result for the interference color image and other information on the display unit 10 together.

[Lubricant temperature measurement]
The film thickness distribution measuring apparatus according to the present invention may include a temperature measurement unit 18 and a temperature recording unit 19 in addition to the above-described configuration.

  The temperature measurement unit 18 measures the temperature of the contact portion SP between the substrate 2 and the contact piece 3. Specifically, the temperature measurement unit 18 measures the temperature of the lubricant LB that lubricates the contact portion SP between the disk 20 and the steel ball 30 from the upper side of the disk 20 through the disk 20 in a non-contact manner. Is. More specifically, the temperature measurement unit 18 includes an infrared temperature sensor, and has a function of displaying the measured temperature and outputting a signal and data corresponding to the measured temperature to the outside.

  The temperature recording unit 19 inputs signals and data output from the temperature measuring unit 18 and records the temperature each time. Specifically, the temperature recording unit 19 is configured as a part of the computer unit 9 or an independent device such as a data logger, and records the temperature at a preset interval or based on an external trigger signal. The temperature can be recorded as appropriate. The temperature recording unit 19 can also record the date and time as necessary when recording the temperature.

  By providing such a temperature measuring unit 18 and a temperature recording unit, the temperature of the contact portion SP can be measured and recorded during the film thickness distribution measurement time. It can be used for analyzing the behavior of the state.

  The temperature measurement unit 18 is not limited to the configuration in which the temperature is measured in a non-contact manner through the disk 20 using the infrared temperature sensor as described above, but by a thermocouple probe or the like disposed below the disk 20. The structure which directly measures the temperature of the steel ball 30 or the temperature of the lubricant LB may be used.

[Modification of substrate]
Further, in the above description, the substrate 2 is a flat glass disk 20, and a metal thin film 21 such as chromium and a transparent film 22 such as silicon oxide are formed on the lower surface thereof, and contact with the contact piece 3. An example in which the portion SP is a flat surface is shown. However, the shape of the contact portion of the substrate 2 is not limited to such a shape, and may be a curved surface, or may be a flat surface or a groove formed on the curved surface. The shape of the contact portion may be a shape that reproduces or models the shape of a bearing or a sliding object for which the film thickness distribution of the lubricant LB is to be measured. The material of the substrate 2 is not limited to glass, but may be other materials such as sapphire, silicon, and resin.

  In addition, the metal thin film 21 on the lower surface of the substrate 2 is not limited to the above-described chromium, but may be a thin film (also referred to as coating) of aluminum, copper, silver, gold, or the like. In carrying out the present invention, the metal thin film 21 is for generating so-called surface reflected light for obtaining an interference color image. Therefore, the metal thin film 21 may not be formed as long as reflected light is obtained from the interface between the substrate 2 and the lubricant LB.

  Further, the transparent film 22 on the lower surface of the substrate 2 is not limited to the above-described silicon oxide, and may be a film formed of a transparent material close to the refractive index of the lubricant LB. In addition, even if the film thickness of the lubricant LB is thin, the transparent film 22 is measured so that the apparent film thickness is thick in order to increase the measurement resolution, and the film thickness of the transparent film 22 is subtracted later. It is for performing such processing. Therefore, the transparent film 22 on the lower surface of the substrate 2 may not be formed if the thickness of the lubricant LB can provide a desired measurement resolution.

[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 not only by a rotating body but also by a sliding object such as a flat plate piece 35 (that is, a non-rotating object). And the flat piece 35 can be suitably selected from arbitrary materials, such as steel, aluminum, a ceramic, and resin.

[Modification of moving mechanism]
In the above description, the moving mechanism 4 has exemplified the configuration for rotating the disk 20 around the rotation axis of the rotary motor 40. However, the moving mechanism according to the present invention includes an actuator that reciprocates along a straight track, and reciprocates the disk 20 or a non-circular substrate (for example, a rectangle, hexagon, octagon, etc.). It may be.

[Another form]
In the above description, an example in which the contact piece 3 is provided with the steel ball 30 which is a type of the rotating body and the rotating body rotating mechanism 5 is used is shown. However, the rotating body rotating mechanism 5 is not an essential component for embodying the present invention, and may be configured without this. Therefore, in the configuration in which the rotating body rotating mechanism 5 is omitted, the torque measuring unit 55, the traction coefficient calculating unit 15, and the slip rate control unit 16 described above are unnecessary, and thus are omitted.

[Another form]
Further, in the above description, the slip ratio control for controlling the slip ratio between the substrate 2 and the steel ball 30 as the rotating body by controlling at least one of the moving speed of the moving mechanism 4 and the rotating speed of the rotating body rotating mechanism 5. The structure provided with the part 16 was illustrated. According to this configuration, it is possible to measure the film thickness distribution of the lubricant LB by setting an arbitrary slip rate.

However, the slip ratio control unit 16 is not an essential component for embodying the present invention, and may be configured without this. In this case, while rotating the substrate 2 at a constant speed,
1) The steel ball 30 is rotated at a constant speed. 2) The steel ball 30 is passively rotated in accordance with the rotation of the substrate 2. 3) The steel ball 30 is set to be stationary or switched manually. Can be set.

[Another form]
In the above description, the configuration (so-called automatic control method) including the actuator 60 for adjusting the load for pressing the contact piece 3 against the substrate 2 and the pressing load control unit 17 for controlling the pressing load is illustrated. However, the pressing load control unit 17 may be configured to be incorporated in a part of the computer unit 9 instead of the dedicated control unit as described above.

  In addition, the pressing load control unit 17 is not an essential component for embodying the present invention, and is omitted. The position is changed by an external signal while using an elastic body such as a spring or rubber instead of an automatic control system. A configuration (so-called semi-automatic operation method) including an actuator 60 that can perform the above-described operation may be used. 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).

[Another form]
In the above description, the thinnest film thickness information recording for recording the position and film thickness of the thinnest film thickness in the film thickness distribution of the lubricant LB at the contact portion SP of the contact piece 3 with the substrate 2 is performed. The structure provided with the part 13 was illustrated. However, the thinnest film thickness information recording unit 13 is not an essential component for embodying the present invention, and may have a configuration in which this is omitted.

[Another form]
Moreover, in the above, the structure provided with the display part 10 in the film thickness distribution measuring apparatus 1 was illustrated. However, the display unit 10 is not an essential component for embodying the present invention, and may be configured without this. Moreover, 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 10 is provided. good.

[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 disposed between the white lamp 70 and the half mirror 82 as described above, but between the objective lens 83 and the substrate 2, the half mirror 82, and the like. A configuration in which the lens is disposed between the imaging lens 84 or between the imaging lens 84 and the imaging camera 80 may be employed.

  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.

1 Thickness distribution measuring device 2 Substrate 2d Arrow (substrate movement direction, disc rotation direction)
3 Contact piece 3d Arrow (movement direction of contact piece, rotation direction of rotating body)
DESCRIPTION OF SYMBOLS 4 Movement mechanism 5 Rotating body rotation mechanism 6 Load application mechanism 7 Light source part 8 Interference color imaging part 9 Computer part 10 Display part 11 Image recording part 12 Film thickness distribution estimation part 13 Thinnest film thickness information recording part 14 Torque measurement part 15 Traction coefficient calculation unit 16 Slip rate control unit 17 Push load control unit 18 Temperature measurement unit 19 Temperature recording unit 20 Disc (one type of substrate)
21 Metal thin film 22 Transparent film 30 Steel ball (contact piece / one type of rotating body)
31 Shaft 40 Rotating motor 41 Connecting member 50 Rotating motor 51 Shaft 55 Torque measuring section 56 Main body section 57 Shaft 60 Actuator 61 Movable element 63 Bearing section 65 Pushing load measuring section (load cell)
70 White lamp 75 Illumination power supply 80 Imaging camera 81 Lens unit 82 Half mirror 83 Objective lens 84 Imaging lens 85 Color filter 86 Image sensor LB Lubricant SP Contact portion of substrate and steel ball RB Turning radius of steel ball R Thickness of film thickness Measurement target region L1 Light irradiated from the light source unit L2 Light irradiated on the measurement target region of film thickness L3 Light reflected from the measurement target region of film thickness (interference light)
Light that passed through the L4 half mirror (interference light to be imaged)
μ Traction coefficient (friction coefficient)
T Transmission torque Wb Pressing load

Claims (8)

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 substrate with optical transparency;
A contact piece that contacts the substrate via the lubricant;
A moving mechanism for relatively moving the substrate and the contact piece;
A load applying mechanism for applying a load by pressing the contact piece on the substrate side;
A light source unit that emits light of at least three types of wavelengths toward the contact portion of the substrate and the contact piece;
An interference color imaging unit that captures an image of the light reflected from the contact portion of the substrate and the contact piece through the substrate and acquires a color interference fringe as an interference color image;
It has a computer part,
In the computer part,
An image recording unit that records an interference color image captured by the interference color imaging unit;
Of the interference color images recorded in the image recording unit, color separation is performed for each light of the at least three wavelengths from the color information of each point included in the selected interference color image, and a luminance 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 contact portion between the substrate and the contact piece is lubricated from the calculated plurality of film thickness candidates. A film thickness distribution measuring apparatus comprising a film thickness distribution estimating unit for estimating the film thickness distribution of the agent. The computer unit includes a thinnest film thickness information recording unit for recording the position and film thickness of the thinnest film thickness in the lubricant film thickness distribution at the contact portion between the substrate and the contact piece. The film thickness distribution measuring apparatus according to claim 1, wherein: At least one of the selected interference color image, an image representing the film thickness distribution of the lubricant estimated by the film thickness distribution estimation unit in a two-dimensional distribution, and an image represented in a three-dimensional manner And a display unit for displaying the position information and the film thickness information of the thinnest film thickness recorded in the thinnest film thickness information recording unit at a time. Film thickness distribution measuring device. The contact piece is a rotating body that rotates while contacting the substrate via the lubricant,
The film thickness distribution measuring apparatus according to claim 1, further comprising a rotating body rotating mechanism that rotates the rotating body. A pressing load measuring unit for measuring a pressing load pressing the contact piece against the substrate;
A torque measuring unit disposed between the rotating body and the rotating body rotating mechanism to measure a transmission torque during rotation of the rotating body;
A traction coefficient calculation unit that calculates a traction coefficient based on the transmission torque measured by the torque measurement unit, the rotation radius of the rotating body, and the pressing load;
The film thickness distribution measuring apparatus according to claim 4, wherein the film thickness measurement and the calculation of the traction coefficient are performed simultaneously.   And a slip ratio control unit that controls a slip ratio between the substrate and the rotating body by controlling at least one of a moving speed of the moving mechanism and a rotating speed of the rotating body rotating mechanism. The film thickness distribution measuring apparatus according to claim 4 or 5. The film thickness distribution measuring apparatus according to any one of claims 1 to 6, further comprising a pressing load control unit that controls a pressing load that presses the contact piece toward the substrate in the load applying mechanism. A temperature measuring unit for measuring a temperature of a lubricant that lubricates a contact portion between the substrate and the contact piece;
The film thickness distribution measuring device according to claim 1, further comprising a temperature recording unit that records the temperature of the lubricant measured by the temperature measuring unit.

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