JP7762584B2 - Contact displacement measuring instrument, scale for contact displacement measuring instrument, manufacturing method for scale for contact displacement measuring instrument, and manufacturing device for scale for contact displacement measuring instrument - Google Patents

Description

The present invention relates to a contact-type displacement measuring instrument, a scale for a contact-type displacement measuring instrument, a method for manufacturing a scale for a contact-type displacement measuring instrument, and an apparatus for manufacturing a scale for a contact-type displacement measuring instrument.

A contact-type displacement measuring instrument is known that has a contactor that is brought into contact with the surface of an object and can move linearly in one direction.

Patent Document 1 describes such a contact displacement measuring instrument as including: "a housing; a contact supported on the housing so as to be movable in one direction; a scale having a first number of light-transmitting portions aligned in the one direction and configured to be movable in the one direction together with the contact; a light-emitting unit that irradiates non-parallel light onto the scale; a light-receiving unit that receives the non-parallel light that has passed through a second number of light-transmitting portions of the scale that is smaller than the first number and outputs a light-receiving signal indicating a distribution of the amount of received light; a detection unit that detects, based on the light-receiving signal output from the light-receiving unit, the second number of positions where the amount of received light in the distribution of the amount of received light at the light-receiving unit is a maximum or minimum as the second number of peak positions; and a detection unit that detects at least one peak position of the first number of light-transmitting portions of the scale detected by the detection unit." and a calculation unit that calculates the distance between a reference position and the position of at least one light-transmitting portion corresponding to the at least one peak position detected by the detection unit, wherein the light-projecting unit, the scale, and the light-receiving unit are provided on the housing so as to be aligned in a direction intersecting the one direction, and the calculation unit calculates at least two magnifications that are ratios between the spacing between three or more peak positions that belong to a predetermined range and the spacing between three or more light-transmitting portions that correspond to the three or more peak positions, and considers the calculated at least two magnifications to be equal to each other, and identifies at least one light-transmitting portion that corresponds to at least one peak position detected by the detection unit based on the spacing between the first number of light-transmitting portions and the spacing between the second number of peak positions."

JP 2015-169559 A

Conventional contact displacement meters such as those described in Patent Document 1 form complex light-transmitting sections on a scale, store in a database in a storage section (memory) a correspondence between a specific distribution of received light amounts (hereinafter also referred to as a "pattern image") obtained by irradiating light and the absolute position, and determine the absolute position by comparing this with the measurement results.
In this case, the procedure for determining absolute position required a communication operation in which a sensor reads an optical "pattern" corresponding to the absolute position on the scale, queries a database about that signal, and returns the corresponding absolute position.

With contact-type displacement sensors like those mentioned above, it took time to query the absolute position database corresponding to the pattern image and to communicate the readout, resulting in insufficient response speed. This made it difficult to measure the surface shape of an object in real time and continuously.

An object of the present invention is to provide a contact-type displacement measuring instrument that can measure absolute position at higher speeds. Another object of the present invention is to provide a scale for a contact-type displacement measuring instrument, a method for manufacturing a scale for a contact-type displacement measuring instrument, and an apparatus for manufacturing a scale for a contact-type displacement measuring instrument.

As a result of extensive research into resolving the above-mentioned problems, the inventors have discovered that the following configuration can solve the above-mentioned problems.

[1] A contact displacement measuring instrument comprising: a housing; a contactor supported by the housing so as to be movable in one direction; a scale configured to be movable in the one direction together with the contactor, the scale having a surface pattern whose roughness gradually increases along the one direction from one end to the other end of the scale; a light source unit that irradiates a surface of the scale with parallel light; a light receiving unit that takes in light reflected from the scale and converts an optical signal of the reflected light into an electrical signal corresponding to the brightness of the light; and a calculation unit that determines an absolute position on the scale corresponding to the electrical signal, wherein the calculation unit determines the absolute position based on a pre-stored function that defines the relationship between the electrical signal and the absolute position.
[2] The scale has the surface pattern on each of the opposing main surfaces, the light source unit irradiates the parallel light onto each of the main surfaces, and the light receiving unit captures the reflected light from each of the main surfaces. The contact displacement measuring instrument described in [1].
[3] The contact displacement measuring instrument according to [2], wherein the calculation unit sums up the electrical signals obtained from each of the main surfaces and determines the absolute position based on the function.
[4] The contact displacement measuring instrument according to [2] or [3], wherein the surface patterns of the respective main surfaces are the same.
[5] A scale for a contact displacement measuring instrument, comprising a flat substrate, at least one main surface of which has a surface pattern whose roughness gradually increases along the longitudinal direction from one end to the other end.
[6] The scale for a contact displacement measuring instrument according to [5], having the surface pattern on each of the opposing main surfaces of the substrate.
[7] The scale for a contact displacement measuring instrument according to [6], wherein the surface pattern on each of the main surfaces is the same.
[8] A method for manufacturing a scale for a contact displacement measuring instrument according to any one of [5] to [7], which includes irradiating at least one of the main surfaces of the flat substrate with a laser while moving the irradiation position along the longitudinal direction from one end to the other end of the main surface, thereby forming the surface pattern.
[9] The manufacturing method according to [8], wherein the moving speed of the irradiation position on the substrate is gradually increased or gradually decreased.
[10] The manufacturing method according to [8], wherein the irradiation energy of the laser is gradually increased or decreased.
[11] A manufacturing device for a contact displacement measurement scale, comprising: a laser irradiation unit for irradiating at least one main surface of a flat substrate with a laser; a movement mechanism for moving the irradiation position of the laser along the longitudinal direction from one end of the substrate to the other end; and a control device, wherein the control device gradually increases or decreases the movement speed of the irradiation position to form a surface pattern on at least one main surface of the substrate whose roughness gradually increases along the longitudinal direction from one end to the other end.
[12] A manufacturing device for a contact displacement measurement scale, comprising: a laser irradiation unit for irradiating at least one main surface of a flat substrate with a laser; a movement mechanism for moving the irradiation position of the laser along the longitudinal direction from one end to the other end of the substrate; and a control device, wherein the control device gradually increases or decreases the irradiation energy of the laser to form a surface pattern on at least one main surface of the substrate whose roughness gradually increases along the longitudinal direction from one end to the other end.

The present invention provides a contact displacement measuring instrument that can measure absolute position at higher speeds. The present invention also provides a scale for a contact displacement measuring instrument, a method for manufacturing a scale for a contact displacement measuring instrument, and a manufacturing device for a scale for a contact displacement measuring instrument.

1 is a block diagram showing the configuration of a displacement measuring instrument according to an embodiment of the present invention. 1 is an explanatory diagram of a measurement head of a displacement measuring instrument according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of the internal structure of the measuring head 12. FIG. 2 is an explanatory diagram of a scale according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the relative positions of a light source unit, a light receiving unit, and a scale. FIG. 1 is an explanatory diagram of one form of length measurement using a displacement measuring instrument equipped with a scale having the same surface pattern on each of the front and back principal surfaces. FIG. 1 is an explanatory diagram of one form of length measurement using a displacement measuring instrument equipped with a scale having the same surface pattern on each of the front and back principal surfaces. 1 is a flowchart of a method for manufacturing a scale for a contact displacement measuring instrument according to an embodiment of the present invention. FIG. 1 is an explanatory diagram of a manufacturing device for a contact type displacement measurement scale that can be used to form a surface pattern. FIG. 10 is an explanatory diagram of a modified example of the manufacturing device for the contact displacement measuring scale.

The present invention will be described in detail below.
The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.
In this specification, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.

The embodiment shown below is an example that embodies the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, and arrangements of the components to the embodiment shown below. The drawings are schematic. Therefore, the relationship and ratio between thickness and planar dimensions may differ from the actual ones, and the dimensional relationships and ratios may also differ between the drawings.

In addition, this specification uses a Cartesian coordinate system to define directions. With the scale for a contact-type displacement measuring instrument (hereinafter simply referred to as "scale") at the center, the direction toward the top of the scale is referred to as the "Z+ direction," and the opposite direction is referred to as the "Z- direction." One direction perpendicular to the Z+ direction (the longitudinal direction of the scale) is referred to as the "X+ direction," and the opposite direction is referred to as the "X- direction." One direction perpendicular to the Z+ and X+ directions (the width direction of the scale) is referred to as the "Y+ direction," and the opposite direction is referred to as the "Y- direction." This Cartesian coordinate system is also shown in each drawing as necessary to clarify directions. The terms "X direction," "Y direction," and "Z direction" simply refer to the respective (+) and (-) directions.

[Contact-type displacement measuring instrument]
A contact-type displacement measuring instrument according to an embodiment of the present invention (hereinafter also referred to as "this displacement measuring instrument") comprises a housing, a contactor supported by the housing so as to be movable in one direction, a scale configured to be movable in the one direction together with the contactor, the scale having a surface pattern whose roughness gradually increases along the one direction from one end to the other end of the scale, a light source unit that irradiates the scale with parallel light, a light-receiving unit that takes in light reflected from the scale and converts an optical signal of the reflected light into an electrical signal according to the brightness of the light, and a calculation unit that determines an absolute position on the scale corresponding to the electrical signal, wherein the calculation unit determines the absolute position based on a pre-stored function that defines the relationship between the electrical signal and the absolute position.

The inventors have investigated the reasons for the insufficient (slow) response speed of conventional contact displacement meters. As a result, they have discovered that in order to calculate absolute position, conventional contact displacement meters require a procedure of querying a database about the pattern image detected by the sensor and obtaining the absolute position that matches that pattern image, and that this procedure is the bottleneck in the entire length measurement process.

Having discovered the above new problem, the inventors conducted extensive research to find a solution. As a result, they discovered that the above problem could be solved by using a scale with a surface pattern in which the roughness gradually increases from one end to the other along the (possible) direction of movement, and thus completed the present invention.

The above scale has a surface pattern in which roughness gradually increases along the direction of movement (X+ direction or X- direction). Therefore, when parallel light is irradiated onto it, the brightness of the image obtained by the reflected light changes depending on the position on the scale, i.e., depending on the roughness of the scale surface at that position. Looking at the entire scale, the brightness of the image obtained by the reflected light gradually decreases from one end to the other.

By storing the relationship between the electrical signal (e.g., voltage) based on the brightness of the image obtained by this reflected light (hereinafter referred to as the "optical signal from reflected light") and the position on the scale (absolute position) as a function in advance, the position on the scale (absolute position) can be instantly calculated using this function from the magnitude of the electrical signal obtained by measurement.

This displacement measuring device eliminates the need to query (communicate) a database for pattern images and can calculate absolute position with simple calculations, significantly improving response speed compared to conventional technology. Below, we will explain in detail this displacement measuring device, which can measure absolute position at high speed, with reference to the drawings.

Figure 1 is a block diagram showing the configuration of the displacement measuring instrument 1. The displacement measuring instrument 1 is broadly composed of a measuring head 12 including a contactor 10 and a scale 11, and a control unit 13 that is electrically connected to the measuring head 12 and controls each part of the measuring head 12.

The measurement head 12 has a contact 10 supported on the housing so that it can move in one direction (X+ direction, X- direction), a scale 11 that is configured to move in one direction together with the contact 10, a light source unit 14 that irradiates the surface of the scale 11 with parallel light CL, and a light receiving unit 15 that captures reflected light RL from the scale 11 and converts the optical signal generated by the reflected light RL into an electrical signal corresponding to its brightness.

On the other hand, the control unit 13 has a power supply/control unit 16 that supplies power to and controls the light source unit 14, the light receiving unit 15, etc., an A/D conversion unit 17 that converts the analog electrical signal from the light receiving unit 15 into a digital signal, and a calculation unit 18 that determines the absolute position on the scale corresponding to the electrical signal.
The displacement measuring instrument 1 further comprises a display unit 19 for displaying the absolute value determined by the calculation unit 18 .

The measuring head 12 and display unit 19 are connected to the control unit 13 via wired or wireless connection. The control unit 13 includes, as hardware, a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array), memory, a power supply, an A/D converter, an interpolator, etc.

The light source unit 14 includes, for example, an LED (Light Emitting Diode), a laser with reduced output for detection, etc. Furthermore, the light source unit 14 has an optical element such as a collimator lens so as to emit parallel light.
In the displacement measuring instrument 1 , parallel light CL emitted from the light source unit 14 is reflected by the surface of the scale 11 , and reflected light RL is taken in by the light receiving unit 15 .
Diffuse reflection occurs on the surface of the scale 11 according to the surface roughness at that position, and the brightness of the image obtained by the light receiving unit 15 changes according to the roughness (as the roughness increases, the brightness decreases).

The LED that can be used as the light source unit 14 may be one that has optical elements such as lenses pre-installed so that the emitted light is parallel. Such an LED may be a commercially available product, and for example, an infrared LED manufactured by Hamamatsu Photonics K.K. (e.g., product name "L9437") and a parallel light LED manufactured by Kyoto Semiconductor Co., Ltd. (e.g., product name "KED358-H23") may be used as a parallel light LED for optical encoders.
It is also possible to use an LED that does not incorporate an optical element such as a lens, and in such a case, an optical element such as a collimator lens is used in combination with the LED to emit parallel light to form the light source unit 14. As such an LED, for example, a high-output red light-emitting diode manufactured by Hamamatsu Photonics K.K. (e.g., product names "L3882,""L6108," and "L6112") can be used.

The wavelength of the light emitted from the light source unit 14 is not particularly limited, as long as it is optimized in relation to the light receiving unit 15. In other words, the light receiving unit 15 needs to be compatible with the wavelength range of the light emitted from the light source unit 14.

The wavelength of the light emitted from the light source unit 14 may be selected appropriately in relation to the material of the scale, which will be described later. For example, if the surface (reflective surface) of the scale is a chrome (Cr) pattern, it is preferable to use a parallel light LED in the red to (near) infrared region as the light source unit 14.
Alternatively, if the surface (reflective surface) of the scale is made of Si, it is preferable that the output (sensitivity of the light receiving section 15) is not impaired by the influence of transmission or absorption in the visible light to near infrared region.

The displacement measuring instrument 1 calculates the absolute position of the surface of the scale 11 from the brightness resulting from the roughness at that position. Therefore, when light is reflected from the surface of the scale 11, scattering (stray light) caused by factors other than roughness is suppressed by configuring the light source unit 14 to emit parallel light CL.

In one form, the light receiving unit 15 is a sensor having a light receiving surface made up of a plurality of light receiving elements (pixels) arranged in a matrix in the width direction (Y direction) and the longitudinal direction of the scale 11. As the light receiving unit 15, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, or the like can be used. Note that the light receiving unit 15 may also be a line sensor made up of light receiving elements arranged in the width direction of the scale 11.
An analog electrical signal representing the distribution of the amount of light received on the light receiving surface is output from the light receiving surface of the light receiving unit 15. This electrical signal has a luminance value corresponding to the roughness of the irradiation surface (reflection surface) onto which the parallel light CL from the light source unit 14 is irradiated.

The analog electrical signal input to the control unit 13 is taken in by the A/D conversion unit 17, sampled at a fixed sampling period, and converted into a digital signal. The brightness data converted into a digital signal is sequentially stored in memory.
Although the displacement measuring instrument 1 has the light receiving unit 15 and the A/D conversion unit 17, the light receiving unit 15 (image sensor) may have an A/D conversion circuit. In this case, the control unit 13 does not need to have an A/D conversion unit.

The control unit 13 has a power supply/control unit 16 and a calculation unit 18 as functions realized by the CPU (or FPGA) executing a program stored in the memory.
The power supply/control unit 16 supplies power to the light source unit, the light receiving unit, etc., and controls them.

The calculation unit 18 performs a calculation process for calculating the absolute position of the surface (irradiation surface) of the scale 11 irradiated with the parallel light CL based on the brightness data stored in the memory.
This calculation is performed based on a function that defines the relationship between a known absolute position and the brightness data (e.g., voltage) corresponding to that position. Since the scale 11 has a surface pattern with gradually increasing roughness along one direction (X+ direction), the resulting brightness gradually decreases along one direction (X+ direction).
According to the above, the absolute position can be calculated simply by applying the measured brightness data to the above function, which significantly speeds up processing compared to the conventional method of querying and matching the measured pattern image against a database and retrieving the corresponding absolute position information.

The absolute position calculated by the calculation unit 18 is sent to and displayed on the display unit 19. The display unit 19 is configured, for example, by a seven-segment display.

Next, the measuring head 12 and the scale 11 included therein will be described in detail.
2A and 2B are explanatory diagrams of the measuring head 12 of the displacement measuring instrument, with FIG. 2A being an external view and FIG. 2B being a longitudinal sectional view.
The measuring head 12 has a housing 20 and a contact 10 supported by the housing 20 so as to be movable in one direction (X direction).

A round rod-shaped shaft 21 is attached to the contact 10 and is supported by a bearing 22 so as to be slidable in the X direction. A bellows boot 23 is attached between the tip of the bearing 22 in the X direction and the contact 10.
The housing 20 is made up of a cylindrical case 24 connected to the tip of the bearing 22 in the X+ direction, a cylindrical cover 25 fitted to the case 24, and a cylindrical outer cover 26 that covers the outside of these, thereby making the entire measuring head 12 airtight. Note that the outer cover 26 is not shown in Figure 2(b).

A terminal section 30 is provided at the X+ end of the cover 25 to which a signal line 27 and an electrical wire 28 for connection to the control unit 13 are connected. The terminal section 30 and the cover 25 are sealed airtight using a mechanical sealing means such as an O-ring, or by adhesive bonding. A cable extending to the control unit 13 is connected to the terminal section 30, but is not shown in the figure.

Next, a stepped shaft portion 31 is connected to the lower end of the shaft 21 in the X+ direction. A rotation stopper 32 that protrudes outward is disposed at one circumferential position on the stepped shaft portion 31. A retaining portion 34 with a smaller diameter than the stepped shaft portion 31 is connected to the lower end of the stepped shaft portion 31 in order to wind a coil spring 33 around it.

Figure 3 is an explanatory diagram of the internal structure of the measuring head 12. Figure 3(a) is a perspective view showing the stepped shaft portion 31, holding portion 34, scale 11, etc. (hereinafter collectively referred to as "movable portion") with the cover 25 and case 24 removed. Figure 3(b) is a perspective view showing the case 24, etc. (hereinafter also referred to as "fixed portion") with the cover 25 removed.

The retaining portion 34 is cylindrical (solid shaft-like) from the stepped shaft portion 31 to the middle portion in the X+ direction, but from the middle portion to the end of the shaft in the X+ direction, cut-off portions 35 and 36 are formed, which have a semicircular cross section cut off in the horizontal plane.

To accommodate the scale 11, a girder frame 38 is formed on the X+ side of the cutout 35 on the Z+ side. The girder frame 38 is cut horizontally from the semicircular shape by the thickness of the scale 11, and has openings 37 cut into it to expose the light-receiving surfaces on the front and back of the scale 11 in the Z+ and Z- directions. The scale 11 is attached to the girder frame 38 using adhesive or the like, and is formed so that the top surface of the cutout 35 is flush with the top surface of the scale 11.

On the other hand, a cutout portion 36 with a semicircular cross section is formed in the Z- direction of the opening 37, and the main surface of the scale 11 supported by the girder frame 38 on the Z- direction side is exposed through the opening 37. The movable portion configured as described above moves in the X direction within the fixed portion. Note that although the coil spring 33 is not shown in Figure 3(a), the coil spring 33 is wound around the lower end of the stepped shaft portion 31 in the X+ direction.

On the other hand, the case 24 that constitutes the fixed part is formed with multiple complexly shaped cutouts created by wire electric discharge machining or the like. The left half of the fixed part is formed in a hollow cylindrical shape to accommodate the coil spring 33 inside, and is shaped to accept the movable part. An oval groove is formed on the top surface in the Z+ direction, which acts as a stop groove that allows the movable part's stop 32 to move longitudinally.

A hole is formed on the underside of the case 24, which is used for adjustments, etc. The coil spring 33 is held between the wall surface of the stepped shaft portion 31 of the movable part. The coil spring 33 is used to return the contact 10 to the X-direction after using the displacement measuring instrument 1.

In the center of the case 24, platform-shaped board receiving portions 39 and 40 are formed on the upper side (Z+ direction) and lower side (Z- direction) of the scale 11, respectively, and electronic boards 44 and 45, on which detection systems 42 and 43 including a light source unit 14 and a light receiving unit 15 are mounted, are mounted together with a board receiving portion 41 formed at the end of the axis in the X+ direction.
The electronic boards 44 and 45 are provided at positions facing each other with the scale 11 in between, and the detection systems 42 and 43 are arranged so that the distances between them and the scale 11 are approximately the same.

Electronic board 44 is placed on board receiving portions 39 and 41 and secured in place by screws 46 and 47. Electronic board 45 is similarly secured to board receiving portions 40 and 41.

With the electronic boards 44 and 45 fixed to the board receiving portions 39, 40, and 41, the horizontal heights of the board receiving portions 39, 40, and 41 are set so that the distance between the light receiving surfaces of the light receiving portions included in the detection systems 42 and 43 and the upper and lower surfaces of the scale 11 attached to the movable portion is an appropriate distance for optical measurement.
Furthermore, the signal line 27 and the electric wire 28 are attached to the terminal portion 30 on the electronic boards 44 and 45 .

Next, the scale of this displacement measuring instrument will be described.
4A and 4B are explanatory diagrams of the scale 11. Fig. 4A is a perspective view of the scale 11, Fig. 4B and Fig. 4C are a plan view and a bottom view of the scale 11, and Fig. 4D to Fig. 4G are diagrams showing the surface pattern of the scale 11.

The scale 11 is made of a flat substrate, and on one of its main surfaces (front surface a) and the other main surface (back surface b), a surface pattern is formed in which the roughness gradually increases along the longitudinal direction (X+ direction) from one end to the other. In Figures 4(b) and (c), rougher areas are represented in black, and flatter areas are represented in white.

There are no particular restrictions on the range of roughness of the surface pattern of the scale 11. It may be determined appropriately depending on factors such as the sensitivity of the length measurement and the length of the scale. In one embodiment, for example, the arithmetic mean roughness Ra is preferably 10 to 1000 nm. Such a scale can be produced by the methods described below, as well as by etching, polishing, laser irradiation, or a combination of these.
In particular, laser irradiation can roughen the mirror surface, and can also make the surface smooth after grinding or etching.
Furthermore, by irradiating the scale with a laser beam exceeding the processing threshold of the material, it is possible to roughen the surface by ablation. As described above, by using laser irradiation, any surface pattern can be easily produced in the range of arithmetic mean roughness Ra of several tens of nanometers or more.

Note that while the roughness of the scale 11 gradually increases along the X+ direction, the arrangement of the scale 11 in the displacement measuring instrument according to the embodiment of the present invention is not limited to this. The scale 11 may also be arranged so that the roughness gradually increases along the X- direction. In other words, the scale 11 in Figures 4(b) and (c) may be rotated 180 degrees around the Z axis and set on the displacement measuring instrument.

FIG. 4D is a diagram illustrating the surface pattern of the scale 11, with the horizontal axis representing the distance in the X direction (position on the scale) and the vertical axis representing the surface roughness at the corresponding position.
As shown in the figure, as X increases (as the absolute position moves in the X+ direction), the surface roughness at the corresponding position increases.

As described above, the scale 11 in this displacement measuring instrument 1 has a correspondence between absolute position and the surface roughness at that position. When parallel light is irradiated onto this surface, diffuse reflection occurs according to the surface roughness, and the brightness of the resulting image changes. If the relationship between this position and brightness (voltage) is stored in advance as a function, the absolute position can be calculated simply by applying the measured brightness to the function, significantly improving response speed.

In order for there to be a correspondence between the absolute position and the surface roughness at that position, the surface pattern must have a gradually increasing roughness along one direction (X+ direction or X- direction) from one end to the other.

One form of surface pattern on this scale is one in which the roughness increases continuously in one direction, as shown in FIG. 4(d).
Another example is one in which the increase in roughness is not continuous but step-like and discontinuous, as shown in FIGS. 4(e) and 4(f).
As another example, as shown in FIG. 4G, the amount of change in roughness relative to the amount of change in position may change continuously, while the roughness increases overall.

In this specification, "gradually increasing" means that the roughness increases from one end of the scale to the other. Specifically, as shown in Figures 4(d), (f), and (g), the ratio of the change in roughness to the change in distance (position) may always be 0 or greater over the entire region, or, in addition to the above, there may be a region where the change in roughness is greater than 0 when the change in X is 0, as shown in Figure 4(e).
The term "over the entire area" means over the entire area used as a scale (corresponding to the measurement range), and may be an area smaller than the entire area of the main surface.

The ratio of the change in roughness to the change in distance in the surface pattern of the scale is preferably equal to or greater than 0, and more preferably greater than 0. By configuring it as described above, it becomes possible to measure length with higher resolution.

There are no particular restrictions on the size of the scale 11, but in one form, a width of 0.5 to 2 mm is preferable, and the length is determined appropriately depending on the measurement length.

5A, 5B, and 5C are explanatory diagrams showing the relative positions of the light source unit, the light receiving unit, and the scale, where FIG. 5A is a perspective view, FIG. 5B is a side view, and FIG. 5C is a plan view.
A detection system 42 including a light source unit 14-1 and a light receiving unit 15-1 is arranged on the upper side (Z+ direction) of the scale 11, and a detection system 43 including a light source unit 14-2 and a light receiving unit 15-2 is arranged on the lower side (Z- direction).
In plan view, the light source units 14-1 and 14-2, and the light receiving units 15-1 and 15-2 are arranged at positions facing each other (overlapping) with the scale 11 interposed therebetween.
The distances from the light receiving sections 15-1 and 15-2 to the surface of the scale 11 are configured to be approximately the same.

On the upper side (Z+ direction side) of the scale 11, the collimated light CL emitted from the light source unit 14-1 is reflected (at least partially) by the surface (front side) of the scale 11, and the reflected light RL is captured by the light receiving unit 15-1. On the other hand, on the lower side (Z- direction side) of the scale 11, the light source unit 14-2 and the light receiving unit 15-2 are arranged in the same manner as above, and the collimated light emitted from the light source unit 14-2 is reflected by the back surface of the scale and captured by the light receiving unit 15-2.

As already explained, the roughness of the scale 11 gradually increases in the X+ direction, so the brightness of the captured image obtained by the light reflected from the irradiated surface (surface of the scale 11) changes according to this roughness. In other words, as the scale 11 moves and the roughness of the reflective surface changes, the brightness of the captured image also changes accordingly.

By predetermining and storing a function that defines the relationship between this brightness and the absolute position on the scale 11, the absolute position corresponding to the measured brightness can be calculated based on this function. This method enables significantly faster response because it is not necessary to query a database for the obtained pattern image and retrieve (communicate) the corresponding position.

Next, the operation of the displacement measuring instrument 1 will be described.
First, when the contact 10 of the measuring head 12 comes into contact with the object to be measured and moves in the X+ direction, the scale 11 also moves in the X+ direction accordingly. At this time, the control unit 13 controls the light source unit 14 to irradiate the scale 11 with parallel light, and the light receiving unit 15 receives the reflected light. The light receiving unit 15 converts the optical signal generated by the reflected light into an electrical signal corresponding to the brightness.

As described above, the scale 11 has a surface pattern whose roughness gradually increases (or may gradually decrease) along the X+ direction, so the brightness of the image obtained by the light receiving unit 15 corresponds to the surface roughness, i.e., the absolute position.

The calculation unit 18 calculates the absolute position on the scale based on the electrical signal converted by the A/D conversion unit 17. This calculation uses a function that defines the relationship between the electrical signal and the absolute position. As already explained, this function is pre-defined and stored in memory, so the calculation unit 18 can easily calculate the absolute position by applying the electrical signal obtained from the A/D conversion unit 17 to the above function. The calculated absolute position is displayed on the display unit 19.

Furthermore, this displacement measuring instrument 1 has the same surface pattern on each of the opposing main surfaces of the scale 11, which provides various excellent advantages over conventional technology. These excellent advantages are explained below.

The scale 11 has two main surfaces (front and back) that each have the same surface pattern. As already explained, the displacement measuring instrument 1 has two light source units 14-1 and 14-2 that can irradiate one main surface of the scale 11 with parallel light, and two light receiving units 15-1 and 15-2 that can receive reflected light from one main surface of the scale 11, located on the front and back sides of the scale, respectively. Therefore, it is possible to receive reflected light from each of the two main surfaces and calculate absolute position based on the signals received.

One of the benefits of this is redundancy. Absolute position can be calculated using only the electrical signal output from either light-receiving unit 15-1 or 15-2. Therefore, one of the detection systems is normally used, and if a malfunction occurs in one of them, the other detection system can be used to maintain the functionality of the displacement measuring instrument 1.

The scale 11 has the same surface pattern on both of its two main surfaces (front and back), but the surface patterns may be different on the front and back. For example, the front surface may have the surface pattern shown in Fig. 4(d) or (g) and the back surface may have the surface pattern shown in Fig. 4(f) or (e).
The surface pattern in Figure 4(d) or (g) allows for measurement with higher resolution because the roughness increases continuously with increasing position X. On the other hand, the surface pattern in Figure 4(f) or (e) has some areas where the increase in roughness is not continuous with changes in position X, resulting in slightly lower resolution compared to the former. By doing as described above, it is also possible to switch the scale depending on the required resolution.

As can be seen from Figures 5(b) and (c), the light source units 14-1 and 14-2 and the light receiving units 15-1 and 15-2 are arranged in opposing positions across the scale 11. If the front and back surfaces of the scale 11 have the same surface pattern, and the two detection systems 42 and 43 use the same elements (if they are identical), then approximately the same electrical signals will be obtained from the light receiving units on both sides of the scale 11. Using these to calculate the absolute position will enable more accurate length measurements.

FIG. 6 is an explanatory diagram of one form of length measurement using a displacement measuring instrument 1 equipped with a scale 11 having the same surface pattern on both the front and back principal surfaces.
FIG. 6(a) is a side view of the scale 11 and the two opposing electronic boards 44, 45, and (b) shows the electrical signals (image light amount, voltage, etc.) obtained from each light receiving section at that time.

On the upper side of the scale 11 (Z+ direction), the parallel light emitted from the light source unit 14-1 is reflected by the surface of the scale 11, and the reflected light is captured by the light-receiving unit 15-1. Similarly, on the lower side of the scale 11 (Z- direction), the parallel light emitted from the light source unit 14-2 is reflected by the back surface of the scale 11, and the reflected light is captured by the light-receiving unit 15-2.

At this time, the distance from the light receiving unit 15-1 to the surface (upper reflecting surface) of the scale 11 and the distance from the light receiving unit 15-2 to the rear surface (lower reflecting surface) of the scale 11 are configured to be approximately the same.
As shown in Figure 6(a), when the posture of the scale 11 is maintained correctly, the distance L1_out from the reflecting surface to the left end portion of the light receiving unit 15-1, the distance L2_out from the reflecting surface to the left end portion of the light receiving unit 15-2, the distance L1_in from the reflecting surface to the right end portion of the light receiving unit 15-1, and the distance L1_out from the reflecting surface to the right end portion of the light receiving unit 15-2 are approximately the same.

The reflective surface on the scale 11 can be regarded as a light source for the light receiving sections 15-1 and 15-2, and in the case of Figure 6(a) where the distance from each light source (reflective surface) to each of the light receiving sections 15-1 and 15-2 is equal, the amount of image light (for each pixel) is approximately the same across the entire width of the light receiving section (Figure 6(b)).
In FIG. 6B, the horizontal axis represents the width of each light receiving section in the Y direction (pixel position), and the vertical axis represents the amount of image light.

In the above case, the amount of light at each part of the width of light receiving section 15-1 and light receiving section 15-2 is equal, so when these are added together, it can be seen that the amount of light obtained in the width direction of the light receiving section is approximately twice the amount of light obtained at each individual light receiving section.

On the other hand, because the scale 11 needs to move in the X direction, a certain amount of leeway is inevitably required for the "fit" of each part. This can cause the scale 11 to tilt unintentionally while the displacement measuring instrument 1 is in use. When the scale tilts, the distance between the light source (reflective surface) and the light receiving unit changes, which changes the amount of image light and can reduce the accuracy of length measurements.

Figure 6(c) shows a case where a rotational moment (rolling) occurs around the X-axis with respect to the scale 11, causing the scale 11 to tilt downward to the right. At this time, L1_out is smaller than L1_in, while L2_out is larger than L1_in.

Since the amount of image light at the light receiving sections 15-1 and 15-2 varies depending on the distance from the reflecting surface (which can be considered as the light source), the amount of image light in the width direction (Y direction) of the light receiving sections 15-1 and 15-2 is as shown in Figure 6 (d).
That is, in the light receiving section 15-1, the image light amount decreases from the left end to the right end, and in the light receiving section 15-2, the image light amount increases from the left end to the right end.

However, when the image light amounts of the light receiving sections 15-1 and 15-2 are added together, it is found that the total amount is approximately the same as that before the occurrence of rolling, as shown in FIG. 6(d).
This is because, as mentioned above, the amount of image light is related to the distance from the light source (reflective surface), and even when rolling occurs, the sum of L1_out and L2_out and the sum of L1_in and L2_in are approximately the same as before rolling occurred.

In this displacement measuring instrument 1, the distance between the light receiving unit 15-1 and the surface of the scale 11 and the distance between the light receiving unit 15-2 and the surface of the scale 11 are approximately the same, but the above effect can be obtained even if the distances are not the same. In other words, the above effect can be obtained even if one of the detection systems is closer to the scale.

This displacement measuring instrument 1 has light receiving elements located on both the front and back of the scale. Therefore, even if rolling occurs, when the signals obtained from the upper and lower light receiving elements are added together, there is no change in intensity, making it possible to measure distance more stably and accurately.

This relationship also applies when a rotational moment (pitching) occurs around the Y axis with respect to the scale 11. Similar to Figure 6, Figure 7 is an explanatory diagram of one form of length measurement using a displacement measuring instrument 1 equipped with a scale 11 having the same surface pattern on both the front and back principal surfaces.

Figures 7(a) and 7(b) show the image light intensity when the scale 11 is properly oriented. At the back and front ends of light-receiving units 15-1 and 15-2, the image light intensity is approximately equal for each pixel aligned in the X direction. On the other hand, Figure 7(c) shows the case where a rotational moment (pitching) occurs around the Y axis. In this case, as with Figures 6(c) and (d), the sum of the image light intensities of light-receiving units 15-1 and 15-2 is the same as the image light intensity obtained when the scale 11 is properly oriented.

Note that a rotational moment (yawing) may occur around the Z axis for the scale 11, but in this case, the distance between each detection system and the scale 11 does not change, so the impact on measurement accuracy is smaller than that of rolling and pitching. Generally, unintended tilt of the scale 11 is much smaller than the size of the scale 11, so even if yawing occurs, the irradiation position only shifts slightly in the planar direction (X and Y directions), so the impact is smaller.

In the displacement measuring instrument 1, the function used by the calculation unit 18 is defined in advance by adding up the electrical signals obtained from the upper and lower light receiving units. This minimizes the effects of rolling or pitching, even if they occur, enabling more accurate measurements.

[Method of manufacturing a scale for a contact-type displacement measuring instrument]
Next, a method for manufacturing the scale 11 used in this displacement measuring instrument will be described. The scale 11 only needs to have a desired surface pattern, and can be manufactured by a known method.
From the viewpoint of enabling more efficient production, a method for producing a scale for a contact displacement measuring instrument (hereinafter also referred to as "this production method") is preferred, which includes irradiating at least one main surface of a flat substrate with a laser along the longitudinal direction from one end to the other end while moving the irradiation position, thereby forming a surface pattern in which the roughness gradually increases along the longitudinal direction from one end to the other end.
Each step of this manufacturing method will be described in detail below.

FIG. 8 is a flowchart of this manufacturing method.
First, in step S1, the substrate surface is pretreated. The material of the substrate is not particularly limited, and inorganic materials such as metals and ceramics, organic materials such as plastics, and composite materials thereof can be used. Examples of inorganic materials include metals, metal oxides, carbon materials such as graphite, semi-metals such as silicon and germanium, and glass. Among them, quartz glass coated with a metal plating (preferably chrome plating) is preferred from the viewpoint of higher dimensional stability against heat (low expansion coefficient).

Pretreatment methods are not particularly limited, but include grinding and etching. Pretreatment flattens the surface, making the surface pattern formed in subsequent steps more uniform. There are no particular limitations on the grinding and etching methods, and known methods can be used.

This step may be omitted if a substrate that has been surface-treated in advance is used. Also, depending on the accuracy required of the displacement measuring device, this step may also be omitted.

Next, in step S2, the surface of the pretreated substrate is washed and dried. There are no particular limitations on the washing and drying method, and any known method can be used. For example, a method can be used in which the pretreated surface is washed with water, an organic solvent, or a mixture thereof, and then dried under reduced pressure. Note that this manufacturing method does not necessarily have to include this step.

Next, in step S3, the surface of the substrate is irradiated with a laser to form a surface pattern in which the roughness gradually increases along one direction from one end of the main surface to the other end.
In detail, the predetermined surface pattern is formed by irradiating at least one main surface of a flat substrate with a laser along the longitudinal direction from one end to the other end of the substrate while moving the laser irradiation position (beam spot position).

There are no particular limitations on the method for forming a predetermined surface pattern by irradiating the laser while moving the irradiation position, and known methods can be used.
From the viewpoint of forming the scale more efficiently, methods include gradually increasing or decreasing the moving speed of the irradiation position (movement speed control method) and gradually increasing or decreasing the irradiation energy (irradiation energy control method).

First, we will explain surface pattern formation using the movement speed control method. Figure 9 is an explanatory diagram of a manufacturing device for contact-type displacement measurement scales that can be used for surface pattern formation. Figure 9(a) is an explanatory diagram of the configuration of the manufacturing device for contact-type displacement measurement scales, Figure 9(b) is a plan view of the substrate to be processed, and Figure 9(c) is an explanatory diagram of the laser optical system.

The contact displacement measurement scale manufacturing device 50 has a laser irradiation unit consisting of laser optical systems 52 and 53 that face each other across the main surface of the substrate 51, a movement mechanism 54 for moving the substrate 51 in the X direction ("XD" in the figure), and a control device 55. The control device 55 has a substrate speed control unit 56 that controls the movement speed of the substrate 51, and an energy control unit 57 that controls the energy (density) of the laser irradiation. The control device 55 is typically a computer having a CPU, memory, etc., and the functions of the substrate speed control unit 56 and energy control unit 57 are realized by the CPU executing programs stored in the memory.

The laser optical systems 52 and 53 are preferably arranged to face each other across the substrate 51, and are each synchronously controlled by the energy control unit 57. That is, the two laser optical systems 52 and 53 can emit lasers 60 with the same energy density, or lasers 60 whose energy density changes at the same rate. This configuration makes it easier to form identical surface patterns 58 and 59 on the two opposing main surfaces of the substrate 51.

On the other hand, the laser optical systems 52 and 53 may be controlled separately. In this case, different patterns can be formed on the two main surfaces. Furthermore, although the contact displacement measurement scale manufacturing device 50 has two laser optical systems, it may only need to have one laser optical system, as long as it is possible to perform surface treatment on at least one side of the substrate 51.

The output of the laser 60 is not particularly limited and may be selected appropriately depending on the type of the substrate 51, for example, if the substrate 51 is ceramic, it may be 50 to 4,000 W. The output of the laser 60 may be adjusted appropriately depending on the moving speed of the irradiation position 61, and if the moving speed of the irradiation position is fast, the output of the laser 60 may be increased.
For example, if the moving speed of the irradiation position 61 is 7,500 to 10,000 mm/sec, the laser output may be 50 to 500 W in one embodiment.
The energy density at the irradiation position 61 may be appropriately selected depending on the type of substrate, etc., but may be 3 to 1500 MW/cm ² in one embodiment.
In the contact displacement measurement scale manufacturing apparatus 50, the irradiation position 61 is moved by moving the substrate 51 using the moving mechanism 54.

The spot diameter (beam spot diameter) of the laser 60 is not particularly limited, but is preferably selected according to the width of the substrate 51 in a direction substantially perpendicular to the longitudinal direction (width of the substrate). In one embodiment, the beam spot diameter is 1 μm to 10 mm.
The number of repetitions (number of passes) of laser irradiation is not particularly limited, but may be 1 to 30 times in one embodiment.

The shape of the laser spot is not particularly limited, but for example, if the main surface of the substrate 51 is rectangular, a rectangular laser spot will allow for efficient formation of a surface pattern. There are no particular restrictions on the method for obtaining a rectangular laser spot, and any known method can be used. In particular, it is preferable to use a laser optical system having a laser light source, beam expander, mask, and homogenizer in this order, as this will allow for more efficient formation of a laser spot of the desired shape.

9(c) is a schematic diagram showing the laser optical system 52 (and 53) of the contact displacement measurement scale manufacturing apparatus 50. The laser optical system 52 has a light source 62, a beam expander 63, a mask 64, a homogenizer 65, and a condenser lens (plano-convex cylindrical lens) 66.
A laser beam 67 (having a Gaussian energy profile as one form) emitted from a light source 62 has its diameter expanded by a beam expander 63 (laser beam 68 in the figure) and is incident on a mask 64 .

The incident laser 68 is shaped into the desired shape, for example, a rectangle, by the mask 64 (laser 69). At this time, the laser 68 incident on the mask 64 is expanded via the beam expander 63, reducing its energy density, which has the advantage of making the mask 64 less susceptible to deterioration.

The laser 69 shaped by the mask 64 is then converted (homogenized) into a flat-top profile by the homogenizer 65. Homogenization facilitates the production of a scale 11 with a more uniform roughness surface pattern across its width.

The laser 70 homogenized by the homogenizer 65 is focused by a focusing lens (plano-convex cylindrical lens) and processed into a spot shape (laser 60) having a width that corresponds to the width direction of the substrate (or the detection range).
The manufacturing apparatus 50 for a contact displacement measurement scale having the above-described laser optical system 52 (and 53) makes it easier to obtain a scale 11 having a more uniform roughness across the width and a gradual increase (or decrease) in roughness along the length.

The wavelength of the laser 60 used is not particularly limited, but in one embodiment, it is preferably 500 to 1200 nm.
Known continuous wave lasers can be used, such as YVO4 lasers, fiber lasers, excimer lasers, carbon dioxide lasers, ultraviolet lasers, YAG lasers, semiconductor lasers, glass lasers, ruby lasers, He—Ne lasers, nitrogen lasers, chelate lasers, and dye lasers.

Next, the operation of the contact displacement measuring scale manufacturing apparatus 50 when implementing the moving speed control method will be described.
First, when the substrate 51 is set on the moving mechanism 54, which is a stage, the energy control unit 57 controls the laser irradiation unit consisting of the laser optical systems 52 and 53 to start laser irradiation at a predetermined energy density. In conjunction with this, the substrate speed control unit 56 moves the substrate in one direction (the XD direction in the drawing).
By doing so, the irradiation position 61 on the substrate 51 moves (relatively) in the X-direction.

When the substrate 51 starts to move, the substrate speed control unit 56 gradually increases the movement speed. Meanwhile, the energy control unit 57 maintains the energy (density) of the laser irradiation constant. When the movement speed of the substrate 51 is slow, the surface of the substrate is rough, and as the movement speed of the substrate increases, the surface roughness gradually decreases. This makes it possible to produce a substrate 51 (i.e., scale 11) with a surface pattern in which roughness gradually decreases (increases) in one direction.

In the above, we have described a configuration in which the substrate speed control unit 56 gradually increases the movement speed of the irradiation position 61 (i.e., the substrate 51), but the substrate speed control unit 56 may also gradually decrease the movement speed. Even in this case, it is possible to manufacture a substrate 51 (scale 11) having a surface pattern in which the roughness gradually increases (decreases) in one direction.

In addition, although the above describes a configuration in which the energy control unit 57 maintains a constant laser irradiation energy (density), the energy control unit may also gradually increase or decrease the laser irradiation energy. By gradually increasing or decreasing the laser irradiation energy in addition to the movement speed of the irradiation position 61, a wider variety of surface patterns can be formed. As already explained, the surface pattern may be selected appropriately depending on the purpose of the measurement, the desired measurement accuracy, etc.

Next, the operation of the contact type displacement measuring scale manufacturing apparatus 50 when implementing the energy density control method will be described.
First, when the substrate 51 is set on the moving mechanism 54, the substrate speed control unit 56 moves the substrate 51 in a fixed direction (the XD direction in the figure) at a predetermined speed. In response to this, the energy control unit 57 gradually increases the energy (density) of the laser irradiation. As a result, as the energy (density) increases, the surface of the substrate 51 becomes rougher, and it is possible to produce a substrate 51 (scale 11) having a surface pattern in which the roughness gradually decreases (increases) in one direction.

In the above, we have described a configuration in which the energy control unit 57 gradually increases the energy (density) at the irradiation position 61, but the energy control unit 57 may also gradually decrease the irradiation energy. Even in this case, it is possible to manufacture a substrate 51 (scale 11) having a surface pattern in which the roughness gradually increases (decreases) in one direction.

In addition, although the above description has been given of a configuration in which the substrate speed control unit 56 maintains a constant movement speed of the substrate 51, the substrate speed control unit 56 may also gradually increase or decrease the movement speed of the substrate 51. By gradually increasing or decreasing the movement speed of the substrate 51 in addition to the energy density, a wider variety of surface patterns can be formed. As already described, the surface pattern may be selected appropriately depending on the purpose of the measurement, the desired measurement accuracy, etc.

Figure 10 is an explanatory diagram of a modified example of a manufacturing device for contact displacement measurement scales. The manufacturing device 80 for contact displacement measurement scales differs from the manufacturing device 50 for contact displacement measurement scales in that the substrate 51 is fixed, and the laser 60 is scanned to move the irradiation position 61.

The contact displacement measurement scale manufacturing device 80 has a laser irradiation unit including laser optical systems 81 and 82 that face each other across the main surface of the substrate 51, a holding mechanism 84 having a holder 83 for holding the substrate 51, a conveying mechanism 86 having a belt 85 for conveying the substrate 51 to the irradiation position 61 of the laser 60, and a control device 55, and the control device 55 has a scanning speed control unit 87 that controls the scanning speed of the laser irradiation position, and an energy control unit 57 that controls the energy (density) of the laser irradiation.
In the manufacturing device 80 for contact displacement measurement scales, the laser irradiation section has, in addition to laser optical systems 81 and 82, a scanning mechanism composed of a polygon mirror or the like, and is configured to be able to move the irradiation position 61 in the XD direction on the substrate 51.

Next, the operation of the contact displacement measuring scale manufacturing apparatus 80 when implementing the moving speed control method will be described.
First, when the substrate 51 is held by the holder 83, the scanning speed control unit 87 moves the irradiation position 61 in the XD direction and gradually increases the moving speed. In accordance with this, the energy control unit 57 controls the energy (density) of the laser irradiation so that it is constant at the irradiation position 61. As a result, as the scanning speed increases, the roughness of the surface of the substrate 51 becomes smaller, and it is possible to manufacture the substrate 51 (scale 11) having a surface pattern 58 in which the roughness gradually decreases (increases) in one direction.

In the above, we have described a configuration in which the scanning speed control unit 87 gradually increases the movement speed of the irradiation position 61 (i.e., the laser scanning speed), but the scanning speed control unit 87 may also gradually decrease the movement speed of the irradiation position 61. Even in this case, it is possible to manufacture a substrate 51 having a surface pattern 58 in which the roughness gradually increases (decreases) in one direction.

In addition, although the above describes a configuration in which the energy control unit 57 maintains a constant laser irradiation energy (density), the energy control unit 57 may also gradually increase or decrease the laser irradiation energy. By gradually increasing or decreasing the laser irradiation energy in addition to the movement speed of the irradiation position 61, a wider variety of surface patterns can be formed. As already explained, the surface pattern may be selected appropriately depending on the purpose of the measurement, the desired measurement accuracy, etc.

Next, the operation of the contact type displacement measuring scale manufacturing apparatus 80 when implementing the energy density control method will be described.
First, when the substrate 51 is held by the holder 83, the scanning speed control unit 87 moves the irradiation position 61 in the XD direction at a constant speed. In conjunction with this, the energy control unit 57 controls the energy (density) of the laser irradiation so as to gradually increase at the irradiation position 61. In this way, it is possible to manufacture the substrate 51 (scale 11) having a surface pattern 58 in which the surface roughness of the substrate 51 gradually increases (decreases) as the energy density at the irradiation position 61 increases.

In the above, we have described a configuration in which the energy control unit 57 gradually increases the energy (density) at the irradiation position 61, but the energy control unit 57 may also gradually decrease the energy. Even in this case, it is possible to manufacture a substrate 51 (scale 11) having a surface pattern 58 in which the roughness gradually increases (decreases) in one direction.

In addition, although the above description has been given of a configuration in which the scanning speed control unit 87 maintains a constant movement speed (i.e., scanning speed) of the irradiation position 61, the scanning speed control unit 87 may also gradually increase or decrease the scanning speed. By gradually increasing or decreasing the scanning speed in addition to the energy density, a wider variety of surface patterns can be formed. As already described, the surface pattern may be selected appropriately depending on the purpose of the measurement, the desired measurement accuracy, etc.

1: Displacement measuring instrument, 10: Contactor, 11: Scale, 12: Measuring head, 13: Control unit, 14, 14-1, 14-2: Light source unit, 15, 15-1, 15-2: Light receiving unit, 16: Control unit, 17: A/D conversion unit, 18: Calculation unit, 19: Display unit, 20: Housing, 21: Shaft, 22: Bearing, 23: Bellows boot, 24: Case, 25: Cover, 26: Outer cover, 27: Signal line, 28: Electric wire, 30: Terminal unit, 31: Stepped shaft portion, 32: Anti-rotation, 33: Coil spring, 34: Holding portion, 35, 36: Cut-off portion, 37: Opening, 38: Girder frame 39, 40, 41: Substrate receiving unit, 42, 43: Detection system, 44, 45: Electronic board, 46, 47: Screw, 50, 80: Manufacturing equipment, 51: Substrate, 52, 53, 81, 82: Laser optical system, 54: Movement mechanism, 55: Control device, 56: Substrate speed control unit, 57: Energy control unit, 58, 59: Surface pattern, 60, 67, 68, 69, 70: Laser, 61: Irradiation position, 62: Light source, 63: Beam expander, 64: Mask, 65: Homogenizer, 83: Holder, 84: Holding mechanism, 85: Belt, 86: Conveyor mechanism, 87: Scanning speed control unit

Claims (12)

The housing and
a contact supported by the housing so as to be movable in one direction;
a scale configured to be movable in the one direction together with the contact, the scale having a surface pattern whose roughness gradually increases along the one direction from one end to the other end of the scale;
a light source unit that irradiates a surface of the scale with parallel light;
a light receiving unit that receives reflected light from the scale and converts an optical signal of the reflected light into an electrical signal corresponding to the brightness of the reflected light;
a calculation unit that determines an absolute position on the scale corresponding to the electrical signal,
The calculation unit determines the absolute position based on a pre-stored function that defines the relationship between the electrical signal and the absolute position. the scale has the surface pattern on each of opposing main surfaces,
the light source unit irradiates the parallel light onto each of the main surfaces,
The contact displacement measuring instrument according to claim 1 , wherein the light receiving section receives the reflected light from each of the main surfaces. The contact displacement measuring instrument of claim 2, wherein the calculation unit sums the electrical signals obtained from each of the principal surfaces and determines the absolute position based on the function. The contact displacement measuring instrument according to claim 2 or 3, wherein the surface patterns on each of the principal surfaces are identical. A scale for contact displacement measuring instruments, having a surface pattern on at least one main surface of a flat substrate, the roughness of which gradually increases along the longitudinal direction from one end to the other. The scale for a contact displacement measuring instrument according to claim 5, wherein the surface pattern is provided on each of the opposing main surfaces of the substrate. The scale for a contact displacement measuring instrument according to claim 6, wherein the surface pattern on each of the main surfaces is the same. The method for manufacturing a scale for a contact displacement measuring instrument according to any one of claims 5 to 7, further comprising: irradiating at least one of the main surfaces of the flat substrate with a laser while moving the irradiation position along the longitudinal direction from one end to the other end of the substrate, thereby forming the surface pattern. The manufacturing method described in claim 8, wherein the movement speed of the irradiation position on the substrate is gradually increased or decreased. The manufacturing method described in claim 8, wherein the laser irradiation energy is gradually increased or decreased. a laser irradiation unit for irradiating a laser onto at least one main surface of the flat substrate;
a moving mechanism for moving the laser irradiation position along a longitudinal direction from one end of the base material to the other end thereof;
a control device;
The control device is a manufacturing device for a contact displacement measurement scale, and the control device gradually increases or decreases the movement speed of the irradiation position to form a surface pattern on at least one main surface of the substrate whose roughness gradually increases along the longitudinal direction from one end to the other end. a laser irradiation unit for irradiating a laser onto at least one main surface of the flat substrate;
a moving mechanism for moving the laser irradiation position along a longitudinal direction from one end of the base material to the other end thereof, and a control device;
The control device is a contact displacement measurement scale manufacturing device, in which the control device gradually increases or decreases the irradiation energy of the laser to form a surface pattern on at least one main surface of the substrate, the roughness of which gradually increases along the longitudinal direction from one end to the other end.