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

Abstract

To provide a contact type displacement measuring instrument capable of measuring a length of an absolute position faster.SOLUTION: A contact type displacement measuring instrument has: a housing; a contact piece supported by the housing movably in one direction; a scale configured to move in the one direction together with the contact piece, the scale having a surface pattern gradually increasing in roughness in the one direction from one end thereof to the other end; a light source part which irradiates a surface of the scale with parallel light; a light reception part which receives reflected light from the scale and converts a light signal of the reflected light into an electric signal corresponding to luminance thereof; and an arithmetic part which determines an absolute position on the scale corresponding to the electric signal, wherein the arithmetic part determines the absolute position based upon a previously stored function defining a relation between the electric signal and the absolute position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a contact displacement measuring instrument, a scale for a contact displacement measuring instrument, a method for manufacturing a scale for a contact displacement measuring instrument, and an apparatus for manufacturing a scale for a contact displacement measuring instrument. [Background technology]

[0002] 2. Description of the Related Art A contact type displacement measuring instrument is known that has a contactor that is brought into contact with the surface of an object and is linearly movable in one direction.

[0003] Patent Document 1 describes such a contact type displacement measuring instrument as "a measuring instrument 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 arranged in the one direction and configured to be movable in the one direction together with the contact; a light-emitting portion that irradiates the scale with non-parallel light; a light-receiving portion 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 detecting portion that detects, based on the light-receiving signal output from the light-receiving portion, the second number of positions where the amount of received light becomes maximum or minimum in the distribution of the amount of received light at the light-receiving portion as the second number of peak positions; and a detecting portion that detects, based on the light-receiving signal output from the light-receiving portion, at least one peak position detected by the detecting portion among the first number of light-transmitting portions of the scale." and a calculation unit that calculates a distance between a position of at least one light-transmitting portion corresponding to a peak position detected by the detection unit and a reference position, 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 with the one direction, and the calculation unit calculates at least two magnifications that are ratios between intervals between three or more peak positions that belong to a predetermined range and intervals 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 intervals between the first number of light-transmitting portions and the intervals between the second number of peak positions." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-169559 Summary of the Invention [Problem to be solved by the invention]

[0005] 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 unit (memory) the correspondence between a specific distribution of received light (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.

[0006] With the contact-type displacement sensors described 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, making it difficult to measure the surface shape of an object in real time and continuously.

[0007] Therefore, 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 manufacturing method for a scale for a contact-type displacement measuring instrument, and a manufacturing apparatus for a scale for a contact-type displacement measuring instrument. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[0009] [1] A contact displacement measuring instrument comprising: a housing; a contactor supported on 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; a light source unit that irradiates parallel light onto the surface of the scale; a light receiving unit that captures the light reflected from the scale and converts the optical signal of the reflected light into an electrical signal corresponding to the brightness; 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. [1] A contact displacement measuring instrument as 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 principal 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 identical. [5] A scale for a contact displacement measuring instrument, 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 end. [6] A 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] A 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 comprises irradiating a laser onto at least one of the main surfaces of the flat substrate along the longitudinal direction from one end to the other end of the substrate while moving the irradiation position, 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 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 a laser onto at least one main surface of a flat substrate; 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 a laser onto at least one main surface of a flat substrate; 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 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. [Effects of the Invention]

[0010] The present invention can provide a contact displacement measuring instrument that can measure absolute position at higher speeds. The present invention can also provide a scale for a contact displacement measuring instrument, a method for manufacturing a scale for a contact displacement measuring instrument, and an apparatus for manufacturing a scale for a contact displacement measuring instrument. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing the configuration of a displacement measuring instrument according to an embodiment of the present invention. [Figure 2] 1 is an explanatory diagram of a measurement head of a displacement measuring instrument according to an embodiment of the present invention. [Figure 3] FIG. 2 is an explanatory diagram of the internal structure of the measuring head 12. [Figure 4] FIG. 2 is an explanatory diagram of a scale according to an embodiment of the present invention. [Figure 5]FIG. 2 is an explanatory diagram showing the relative positions of a light source unit, a light receiving unit, and a scale. [Figure 6] 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. [Figure 7] 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. [Figure 8] 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. [Figure 9] 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. [Figure 10] FIG. 10 is an explanatory diagram of a modified example of the manufacturing device for the contact displacement measuring scale. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] 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 following embodiment. The drawings are schematic. Therefore, the relationship and ratio between thickness and planar dimensions may differ from the actual ones, and the relationship and ratio between dimensions may also differ between the drawings.

[0014] Furthermore, 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.

[0015] [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.

[0016] The inventor has investigated the cause of the insufficient (slow) response speed of conventional contact displacement meters, and has found that in order to calculate the absolute position, conventional contact displacement meters require a procedure of querying a database about a pattern image detected by a sensor and obtaining the absolute position that matches the pattern image, and this procedure is the bottleneck of the entire length measurement process.

[0017] Having discovered the above-mentioned new problem, the inventors conducted extensive research to solve it, and as a result found that the above-mentioned problem could be solved by using a scale having a surface pattern in which the roughness gradually increases from one end to the other end along the (possible) direction of movement, and thus completed the present invention.

[0018] The scale has a surface pattern whose roughness gradually increases along the movement direction (X+ direction or X- direction), so 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.

[0019] By storing the relationship between the electrical signal (e.g., voltage) based on the brightness of the image obtained by this reflected light (hereinafter also 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 the function from the magnitude of the electrical signal obtained by measurement.

[0020] This displacement measuring instrument does not need to query (communicate) a database for a pattern image and can calculate absolute position with just a simple calculation, resulting in a significantly improved response speed compared to conventional technology. Below, this displacement measuring instrument, which can measure absolute position at high speed, will be described in detail with reference to the drawings.

[0021] Figure 1 is a block diagram showing the configuration of this displacement measuring instrument 1. The displacement measuring instrument 1 is broadly composed of a measuring head 12 including a contact 10 and a scale 11, and a control unit 13 electrically connected to the measuring head 12 and controlling each part of the measuring head 12.

[0022] The measurement head 12 has a contact 10 supported on a housing so as to be movable in one direction (X+ direction, X- direction), a scale 11 configured to be movable in one direction together with the contact 10, a light source unit 14 that irradiates parallel light CL onto the surface of the scale 11, 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.

[0023] 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. Moreover, the displacement measuring instrument 1 further comprises a display unit 19 that displays the absolute value determined by the calculation unit 18.

[0024] The measuring head 12 and the display unit 19 are connected to the control unit 13 by wire or wirelessly. The control unit 13 includes, as hardware, a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), a memory, a power supply, an A / D converter, an interpolator, and the like.

[0025] The light source unit 14 includes, for example, an LED (Light Emitting Diode), a laser with reduced output for detection, etc. Furthermore, it 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).

[0026] 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 examples of such a parallel light LED for optical encoders include 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") 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 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," etc.) can be used.

[0027] 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, it is sufficient that the light receiving unit 15 corresponds to the wavelength range of the light emitted from the light source unit 14.

[0028] The wavelength of the light emitted from the light source unit 14 may be appropriately selected in relation to the material of the scale, which will be described later. For example, if the surface (reflecting 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. As another example, if the surface (reflecting 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.

[0029] 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. For this reason, when light is reflected on 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.

[0030] As 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.

[0031] 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.

[0032] 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.

[0033] 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 luminance data stored in the memory. This calculation is 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.

[0034] 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 by, for example, a seven-segment display.

[0035] 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 cross-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).

[0036] A round rod-shaped shaft 21 is attached to the contactor 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 contactor 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, making the entire measuring head 12 airtight. Note that the outer cover 26 is not shown in Figure 2(b).

[0037] A terminal section 30 to which a signal line 27 and an electric wire 28 for connection to the control section 13 are connected is disposed at the end of the cover 25 in the X+ direction, and the terminal section 30 and the cover 25 are sealed airtight by a mechanical sealing means such as an O-ring or by adhesive bonding. A cable extending to the control section 13 is connected to the terminal section 30, but is not shown in the drawing.

[0038] Next, a stepped shaft portion 31 is connected to the lower end in the X+ direction of shaft 21. A rotation stopper 32 that protrudes outward is disposed at one circumferential position of stepped shaft portion 31. A holding portion 34 having a smaller diameter than stepped shaft portion 31 is connected to the lower end of stepped shaft portion 31 in order to wind a coil spring 33 around it.

[0039] 3A is a perspective view showing the stepped shaft 31, the holding part 34, the scale 11, etc. (hereinafter collectively referred to as "movable parts") with the cover 25 and the case 24 removed. FIG. 3B is a perspective view showing the case 24, etc. (hereinafter also referred to as "fixed part") with the cover 25 removed.

[0040] The holding portion 34 is cylindrical (solid shaft-like) from the stepped shaft portion 31 side to the middle portion in the X+ direction, but from the middle portion to the shaft end in the X+ direction, cut-off portions 35 and 36 are formed, which have a semicircular cross section cut off in the horizontal plane.

[0041] On the X+ direction side of cutout portion 35 on the Z+ direction side, in order to place scale 11, a girder frame 38 is formed, which is further cut into the semicircular shape in the horizontal plane by the thickness of scale 11 and has openings 37 cut into it so that the light receiving surfaces on the front and back sides of scale 11 are exposed in the Z+ direction and the Z- direction. Scale 11 is attached to girder frame 38 using an adhesive or the like, and is formed so that the top surface of cutout portion 35 and the top surface of scale 11 are flush with each other.

[0042] 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 Z-direction side of the scale 11 supported by the girder frame 38 is exposed in the Z-direction side 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.

[0043] Meanwhile, case 24, which constitutes the fixed part, is formed with multiple notches of complex shapes by wire electric discharge machining or the like. The left half of the fixed part is formed in a hollow cylindrical shape so that coil spring 33 can be housed inside, and is shaped to receive the movable part. An oval groove is formed on the top surface in the Z+ direction, and serves as a rotation stop groove that allows rotation stop 32 of the movable part to move in the longitudinal direction.

[0044] 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 portion. The coil spring 33 is used to return the contact 10 to the X-direction after the displacement measuring instrument 1 has been used.

[0045] 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.

[0046] An electronic board 44 is placed on the board receiving portions 39 and 41 and fixed by screws 46 and 47. An electronic board 45 is fixed to the board receiving portions 40 and 41 in the same manner.

[0047] The horizontal heights of the board receiving portions 39, 40, and 41 are set so that when the electronic boards 44 and 45 are fixed to the board receiving portions 39, 40, and 41, 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 appropriate for optical measurement. Furthermore, the signal line 27 and the electric wire 28 are attached to the terminal section 30 on the electronic boards 44 and 45 .

[0048] Next, the scale of this displacement measuring instrument will be described. Fig. 4 is an explanatory diagram of the scale 11. Fig. 4(a) is a perspective view of the scale 11, Fig. 4(b) and (c) are a plan view and a bottom view of the scale 11, and Fig. 4(d) to (g) are diagrams showing the surface pattern of the scale 11.

[0049] The scale 11 is made of a flat substrate, and on one main surface (front surface a) and the other main surface (back surface b) thereof, 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 4(c), rougher areas are represented in black, and flatter areas are represented in white.

[0050] The range of roughness of the surface pattern of the scale 11 is not particularly limited. It may be determined appropriately depending on the measurement sensitivity, the length of the scale, and the like. 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, and the like, or by a combination of these. In particular, laser irradiation can roughen the mirror surface, and can also make the surface smooth after grinding or etching. In addition, 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 mentioned above, by using laser irradiation, any surface pattern can be easily created within the range of arithmetic mean roughness Ra of several tens of nanometers or more.

[0051] Although 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 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.

[0052] FIG. 4(d) 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.

[0053] 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.

[0054] In order for there to be a correspondence between the absolute position and the surface roughness at that position, the surface pattern needs to have a gradual increase in roughness along one direction (X+ direction or X- direction) from one end to the other end.

[0055] One form of surface pattern on this scale is one in which the roughness increases continuously in one direction, as shown in Figure 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 (f). As another example, as shown in FIG. 4(g), the amount of change in roughness relative to the amount of change in position may change continuously, while the roughness increases overall.

[0056] 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.

[0057] The ratio of the amount of change in roughness to the amount of 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 as described above, it becomes possible to measure length with higher resolution.

[0058] The size of the scale 11 is not particularly limited, but in one embodiment, the width is preferably 0.5 to 2 mm, and the length is determined appropriately depending on the measurement length.

[0059] FIG. 5 is an explanatory diagram showing the relative positions of the light source unit, the light receiving unit, and the scale, where FIG. 5(a) is a perspective view, FIG. 5(b) is a side view, and FIG. 5(c) 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 unit 14-1 and the light source unit 14-2, and the light receiving unit 15-1 and the light receiving unit 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.

[0060] On the upper side (Z+ direction side) of the scale 11, the parallel light CL emitted from the light source unit 14-1 is (at least partially) reflected by the surface (front surface) of the scale 11, and the reflected light RL is taken in 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 parallel light emitted from the light source unit 14-2 is reflected by the back surface of the scale and taken in by the light receiving unit 15-2.

[0061] As already explained, the roughness of the scale 11 gradually increases in the X+ direction, and therefore the brightness of the captured image obtained by the light reflected from the irradiated surface (surface of the scale 11) of the reflected light changes according to the roughness. In other words, when the scale 11 moves and the roughness of the reflecting surface changes, the brightness of the captured image also changes accordingly.

[0062] By predetermining and storing a function that defines the relationship between this brightness and the absolute position on the scale 11, it is possible to calculate the absolute position corresponding to the measured brightness based on this function. This method enables a significantly high-speed response because it is not necessary to query a database for the obtained pattern image and call up (communicate) the corresponding position.

[0063] 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.

[0064] As described above, the scale 11 has a surface pattern whose roughness gradually increases (or may gradually decrease) along the X+ direction, and therefore the brightness of the image obtained at the light receiving unit 15 corresponds to the surface roughness, i.e., the absolute position.

[0065] Based on the electrical signal converted by A / D conversion unit 17, calculation unit 18 calculates the absolute position on the scale. A function that defines the relationship between the electrical signal and the absolute position is used for this calculation. As already explained, this function is predefined and stored in memory, so calculation unit 18 can easily calculate the absolute position by applying the electrical signal obtained from A / D conversion unit 17 to the above function. The calculated absolute position is displayed on display unit 19.

[0066] Furthermore, the present displacement measuring instrument 1 has the same surface pattern on each of the opposing main surfaces of the scale 11, which provides various excellent effects compared to the prior art. These excellent effects will be described below.

[0067] The scale 11 has two main surfaces (front and back surfaces) each having the same surface pattern. As already explained, the displacement measuring instrument 1 has two light source units 14-1 and 14-2 capable of irradiating one main surface of the scale 11 with parallel light, and two light receiving units 15-1 and 15-2 capable of receiving reflected light from one main surface of the scale 11, located on the front and back sides of the scale, respectively, and is therefore also able to receive reflected light from each of the two main surfaces and calculate the absolute position based on the signals received.

[0068] One of the effects of this is redundancy. Since absolute position can be calculated using only the electrical signal output from either one of the light receiving units 15-1 or 15-2, one of the detection systems is normally used, and if a malfunction occurs in that system, the other detection system can be used to maintain the functionality of the displacement measuring instrument 1.

[0069] Although the scale 11 has the same surface pattern on both of its two main surfaces (front and back), 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 measurements 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 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.

[0070] 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 at positions facing each other 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 made identical), then approximately the same electrical signals will be obtained from the light receiving units on both sides of the scale 11. If these are used to calculate the absolute position, more accurate length measurement will be possible.

[0071] 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 and 45, and (b) shows the electrical signals (image light amount, voltage, etc.) obtained from each light receiving section at that time.

[0072] On the upper side (Z+ direction) of the scale 11, 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 taken in by the light receiving unit 15-1. Similarly, on the lower side (Z- direction) of the scale 11, 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 taken in by the light receiving unit 15-2.

[0073] 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.

[0074] 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. 6(b), 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.

[0075] In the above case, the amount of light at each part in the width direction 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.

[0076] On the other hand, since the scale 11 needs to move in the X direction, it is inevitable that a certain amount of leeway is required for the "fit" of each part. This can cause the posture of 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 (reflecting surface) and the light receiving part changes, which changes the amount of light in the image and can be a factor in reducing the accuracy of length measurement.

[0077] 6(c) shows a case where a rotation 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.

[0078] Since the amount of image light at light receiving units 15-1 and 15-2 varies depending on the distance from the reflecting surface (which can be considered the light source), the amount of image light in the width direction (Y direction) of light receiving units 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.

[0079] 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.

[0080] In this displacement measuring instrument 1, the distance between light receiving unit 15-1 and the surface of scale 11 and the distance between light receiving unit 15-2 and the surface of scale 11 are approximately the same, but the above-mentioned effect can be obtained even if the distances are not the same. In other words, the above-mentioned effect can be obtained even if either detection system is closer to the scale.

[0081] In this displacement measuring instrument 1, the light receiving parts are located on the front and back of the scale, so even if rolling occurs, when the signals obtained from the upper and lower light receiving parts are summed up, there is no change in intensity, making it possible to measure length more stably and accurately.

[0082] This relationship also applies when a rotational moment (pitching) occurs around the Y axis with respect to the scale 11. Fig. 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 each of the front and back principal surfaces, similar to Fig. 6.

[0083] 7(a) and 7(b) show the image light intensity when the scale 11 is properly oriented. At the back and front ends of the 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, FIG. 7(c) shows the case where a rotational moment (pitching) occurs around the Y axis. In this case, as in FIGS. 6(c) and 6(d), the sum of the image light intensities of the light-receiving units 15-1 and 15-2 is found to be the same as the image light intensity obtained when the scale 11 is properly oriented.

[0084] Note that a rotational moment (yawing) may occur around the Z axis for the scale 11, but in this case, the impact on measurement accuracy is smaller than that of rolling and pitching because the distance between each detection system and the scale 11 does not change. Generally, unintentional 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 (XY direction), so the impact is smaller.

[0085] 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, so that even if rolling or pitching occurs, the influence of this can be minimized, enabling more accurate length measurements.

[0086] [Manufacturing method for contact type displacement measuring instrument scale] 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.

[0087] FIG. 8 is a flowchart of this manufacturing method. First, in step S1, the substrate surface is pretreated. The substrate material 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 these, quartz glass coated with a metal plating (preferably chrome plating) is preferred from the viewpoint of higher dimensional stability against heat (low expansion coefficient).

[0088] The pretreatment method is not particularly limited, and examples thereof include grinding and etching. By performing the pretreatment, the surface is flattened, and the surface pattern formed in the subsequent step becomes more uniform. The grinding and etching methods are not particularly limited, and known methods can be used.

[0089] This step may be omitted when a substrate that has been surface-treated in advance is used, etc. Furthermore, this step may also be omitted depending on the accuracy required of the displacement measuring instrument.

[0090] Next, in step S2, the surface of the substrate after the pretreatment is washed and dried. The method of washing and drying is not particularly limited, and known methods can be used. For example, a method can be used in which the surface after the pretreatment 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.

[0091] 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).

[0092] There are no particular limitations on the method for forming a predetermined surface pattern by irradiating with a 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).

[0093] First, the surface pattern formation by the moving speed control method will be explained. 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.

[0094] The contact displacement measurement scale manufacturing apparatus 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 the energy control unit 57 are realized by the CPU executing a program stored in the memory.

[0095] The laser optical systems 52 and 53 are disposed opposite each other with the substrate 51 in between, and are preferably controlled synchronously by an energy control unit 57. That is, the two laser optical systems 52 and 53 can emit laser beams 60 with the same energy density or laser beams 60 whose energy density changes at the same rate. This configuration makes it easier to form the same surface patterns 58 and 59 on the two opposing main surfaces of the substrate 51.

[0096] Alternatively, the laser optical systems 52 and 53 may be controlled separately. In this case, different patterns can be formed on the two main surfaces. Although the contact displacement measurement scale manufacturing apparatus 50 has two laser optical systems, it may have only one laser optical system as long as it is possible to perform surface treatment on at least one side of the substrate 51.

[0097] 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 in one embodiment, it is 3 to 1500 MW / cm 2 It may be. In the contact displacement measuring scale manufacturing apparatus 50, the movement of the irradiation position 61 is realized by moving the substrate 51 with the moving mechanism .

[0098] The spot diameter (beam spot diameter) of the laser 60 is not particularly limited, but is preferably selected according to the width in a direction substantially perpendicular to the longitudinal direction of the substrate 51 (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.

[0099] The shape of the laser spot is not particularly limited, but for example, if the main surface of the substrate 51 is rectangular, a surface pattern can be efficiently formed if the laser spot is also rectangular. The method for obtaining a rectangular laser spot is not particularly limited, and known methods can be used. Among these, it is preferable to use a laser optical system having a laser light source, a beam expander, a mask, and a homogenizer in this order, in order to more efficiently obtain a laser spot of a desired shape.

[0100] 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 drawing) and is incident on a mask 64 .

[0101] The incident laser 68 is shaped into a 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, and the energy density is reduced, which has the advantage that the mask 64 is less likely to deteriorate.

[0102] The laser 69 shaped by the mask 64 is then transformed (homogenized) into a flat-top profile by the homogenizer 65. Homogenization helps to produce a scale 11 with a more uniform roughness surface pattern across its width.

[0103] 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.

[0104] 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.

[0105] Next, the operation of the contact type 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.

[0106] When the movement of the substrate 51 begins, 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 manufacture a substrate 51 (i.e., scale 11) having a surface pattern in which the roughness gradually decreases (increases) in one direction.

[0107] Although the above description has been given of a configuration in which the substrate speed control unit 56 gradually increases the moving speed of the irradiation position 61 (i.e., the substrate 51), the substrate speed control unit 56 may also gradually decrease the moving 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.

[0108] Furthermore, although the above description has been given of a mode in which the energy control unit 57 maintains the energy (density) of the laser irradiation constant, the energy control unit may also gradually increase or decrease the energy of the laser irradiation. By gradually increasing or decreasing the energy of the laser irradiation in addition to the moving speed of the irradiation position 61, a wider variety of surface patterns can be formed. As already described, the surface pattern may be appropriately selected depending on the purpose of the measurement, the desired measurement accuracy, etc.

[0109] 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 (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 manufacture a substrate 51 (scale 11) having a surface pattern in which the roughness gradually decreases (increases) in one direction.

[0110] Although the above describes a configuration in which the energy control unit 57 gradually increases the energy (density) at the irradiation position 61, the energy control unit 57 may also be configured to 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.

[0111] Furthermore, although the above description has been given of a configuration in which the substrate speed control unit 56 maintains the movement speed of the substrate 51 constant, 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 as appropriate depending on the purpose of the measurement, the desired measurement accuracy, etc.

[0112] 10 is an explanatory diagram of a modified example of a contact displacement measurement scale manufacturing apparatus. A contact displacement measurement scale manufacturing apparatus 80 differs from the contact displacement measurement scale manufacturing apparatus 50 in that the base material 51 is fixed, and the laser 60 is scanned to move the irradiation position 61.

[0113] 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.

[0114] Next, the operation of the contact type 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 conjunction 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 surface roughness of the substrate 51 becomes smaller, and it is possible to manufacture a substrate 51 (scale 11) having a surface pattern 58 in which the roughness gradually decreases (increases) in one direction.

[0115] Although the above description has been given of a configuration in which the scanning speed control unit 87 gradually increases the moving speed of the irradiation position 61 (i.e., the laser scanning speed), the scanning speed control unit 87 may also be configured to gradually decrease the moving 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.

[0116] Furthermore, although the above description has been given of a mode in which the energy control unit 57 maintains the energy (density) of the laser irradiation constant, the energy control unit 57 may also gradually increase or decrease the energy of the laser irradiation. By gradually increasing or decreasing the energy of the laser irradiation in addition to the moving speed of the irradiation position 61, a wider variety of surface patterns can be formed. As already described, the surface pattern may be appropriately selected depending on the purpose of the measurement, the desired measurement accuracy, etc.

[0117] 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, as the energy density at the irradiation position 61 increases, it is possible to manufacture a substrate 51 (scale 11) having a surface pattern 58 in which the surface roughness of the substrate 51 gradually increases (decreases).

[0118] Although the above describes a configuration in which the energy control unit 57 gradually increases the energy (density) at the irradiation position 61, 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.

[0119] Furthermore, in the above description, the scanning speed control unit 87 maintains the moving speed (i.e., scanning speed) of the irradiation position 61 constant, but the scanning speed control unit 87 may 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 as appropriate depending on the purpose of measurement, the desired measurement accuracy, etc. [Explanation of symbols]

[0120] 1: Displacement measuring instrument, 10: Contact, 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 unit, 32: Rotation stopper, 33: Coil spring, 34: Holding unit, 35, 36: Cut-off portion, 37: Opening, 38: Beam Frame, 39, 40, 41: substrate receiving portion, 42, 43: detection system, 44, 45: electronic substrate, 46, 47: screws, 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: conveying mechanism, 87: scanning speed control unit

Claims

1. 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.

2. 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.

3. The contact displacement measuring instrument according to claim 2 , wherein the calculation unit adds up the electrical signals obtained from each of the main surfaces and determines the absolute position based on the function.

4. 4. The contact displacement measuring instrument according to claim 2, wherein the surface patterns on the respective main surfaces are identical.

5. A scale for a contact displacement measuring instrument, comprising a flat substrate having, on at least one main surface thereof, a surface pattern whose roughness gradually increases along the longitudinal direction from one end to the other end.

6. 6. The scale for a contact displacement measuring instrument according to claim 5, wherein the surface pattern is provided on each of opposing main surfaces of the substrate.

7. 7. 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.

8. 8. A method for manufacturing a scale for a contact displacement measuring instrument according to claim 5, comprising: irradiating at least one of the main surfaces of the flat substrate with a laser while moving an irradiation position along a longitudinal direction from one end toward the other end of the main surface, thereby forming the surface pattern.

9. The manufacturing method according to claim 8 , wherein the moving speed of the irradiation position on the substrate is gradually increased or decreased.

10. The manufacturing method according to claim 8 , wherein the irradiation energy of the laser is gradually increased or decreased.

11. 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 substrate to the other end; 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.

12. a laser irradiation unit for irradiating a laser onto at least one main surface of the flat substrate; a movement mechanism for moving the laser irradiation position along a longitudinal direction from one end of the substrate 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.

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