JP2005037341A - Electronic type length/angle measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely measure a dimensional value without remeasuring it from an origin of a scale, in an electronic type length/angle measuring instrument for measuring a dimension, a position or a moving amount of a measuring object. <P>SOLUTION: A slide block provided with an imaging means is moved on a surface of the linear/circular-arc scale in response to the dimension or the position of the measuring object, a scale mark drawn in the scale surface and positional information are read as image information by a CCD/CMOS element of the imaging means, and a dimension and a positional relation between a specified measuring point and the scale mark in the read-in image information are recognized to be processed to find a moving distance from the dimensional value from the origin or a start point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

Detailed Description of the Invention

  The present invention relates to an electronic length that electronically measures a dimension or a moving amount of an object to be measured using a straight ruler (or tape measure) forming a scale line group, a linear / arc-shaped scale such as a protractor, or a protractor. / It relates to angle measuring instruments.

  Conventionally, an optical linear scale device is known as a kind of electronic length measuring device. This apparatus has a linear linear scale in which graduation lines or slits are formed at regular intervals, and a detection means that is provided movably along the longitudinal direction of the scale and optically detects the scale graduation, This detection means counts the number of scales detected while moving from the origin according to the size of the measurement object or the position or movement amount on a straight line. The position or amount of movement on the line is measured.

In order to perform measurement with high accuracy in the conventional optical linear scale device having such a configuration, it is necessary to set the dimension value from the origin for each scale formed on the scale with high accuracy, which is extremely costly. There was a problem that it would be expensive.
For this reason, there is a need for an electronic or optical scale device that can perform measurement with high accuracy even if the dimension value or rotation angle value from the origin of each scale is not set with high accuracy. In order to meet such demands, for example, there is an optical scale device proposed in Patent Document 1.

JP 2001-221659 (page 3)

Fig. 1)

  In Patent Document 1, the imaging means is moved on the surface of the linear scale in accordance with the dimension of the measurement object, and the graduation line image of the portion facing the camera on the scale is captured and input to a personal computer. Recognize the positional relationship between a specific measurement point in the camera field of view and the graticule line in the input image, and measure the dimensional values from the respective origins of the scale graduation line stored in the external memory of the personal computer. An optical scale that performs a process of obtaining a dimension value of a measurement point from the origin based on the value is disclosed.

However, in the optical scale disclosed in Patent Document 1, it is necessary to provide position information from the origin symbolized corresponding to all scale lines, and the linear scale itself is required to have extremely high accuracy. The problem has not always been solved, and its configuration is complicated. Moreover, although it is supposed that the position information of the measurement points existing between the minimum unit scales (mm) is obtained by ratio distribution, the specific way of obtaining it is not necessarily clear.
In Patent Document 1, the accuracy of a low-precision scale is measured in advance, and the value is stored (storage means = external memory). When actually measured, the scale scale is corrected by correcting the stored value. Although it is disclosed that the measurement can be performed with high accuracy even if the accuracy is not high, it is difficult to measure the accuracy in advance.
On the other hand, the straight scale / tape scale / protractor called home measure does not stay in the home. For example, the straight scale is used as a scale for cutting machines for steel, woodwork, and stone, or after construction of guide rails and traffic signs on the road. For inspection. The tape measure is used for surveying or measuring the body of Japanese and Western style. Protractors are widely used in various situations as angled cutting or humanoid robot joint sensors. In many cases, there is a demand for the realization of a length / angle measuring device that is inexpensive and excellent in working speed even if the accuracy is moderate.

The present invention has been made in order to solve the above-described problems of the prior art, and has a scale formed with a scale line group and an absolute dimension symbol group, and a scale relative to the scale of the measurement object. An imaging means having a CCD / CMOS element that is installed on the slide block and converts information such as graduation line groups and absolute dimension symbol groups on the scale into electronic information, and drives the imaging means. An electronic length / angle measuring device having CCD / CMOS driving means for obtaining digitized image information and the like, and arithmetic processing means for calculating a dimension value of a measurement object based on the obtained image information and the like. The image information of a region associated with a specific graduation line in the visual field by the CCD / CMOS element is recognized as image information relating to an absolute dimension symbol.
In the following description, in order to simplify the description, a length measuring device will be mainly described. However, an angle measuring device using a protractor as a scale has the same configuration and operation.

  In the present invention, the scale is a linear scale in which graduation line groups are formed on the surface at regular intervals, and it is preferable that the slide block is configured to be slidable along the scale. It is not limited to such a configuration. For example, a base such as a commercially available straight ruler (or tape measure), a protractor, etc. is used as the scale body portion on which the scale line group is formed, and the base has a rail-like portion that allows the slide block to slide along the scale. It is good also as a scale of the structure attached to.

The scale line group may be only a reference unit scale line group formed at a single interval. However, when the absolute position information symbol group is formed at an appropriate interval in association with the scale line group, the reference unit It is preferable that an upper unit scale line group is formed at intervals of a predetermined number of scale lines, and the upper unit scale line group and the absolute position information symbol group are associated with each other. That is, on the surface of the scale, at least two types of scale line groups, for example, a group of mm scale lines as a reference unit scale and a group of cm scale lines as an upper unit scale, the reference unit scale is formed. Alternatively, a symbol (absolute dimension symbol) indicating an absolute dimension value from the origin of the unit scale is formed for each predetermined amount range (for example, every 1 cm or every 10 cm) of the upper unit scale.
By adopting such a configuration, the electronic length / angle measuring instrument of the present invention always detects the absolute position of the measurement point at the start of measurement. Unlike the instrument, it is not necessary to return the slide block to the origin for each measurement.

  In the present invention, the imaging means is configured to relatively move in a straight line direction corresponding to the dimension or position of the measurement object on the surface of the linear / arc-shaped scale. There is provided a CCD / CMOS device capable of accommodating a part of a scale line group and an absolute dimension value symbol group formed on the surface of the scale within a specific visual field.

In the present invention, arithmetic processing means is provided, and in this arithmetic processing means, specific measurement points in the visual field and scales in the image information of the scale surface obtained by the CCD / CMOS element of the imaging means. Recognize line positional relationship, scale line group absolute dimension symbol, slide block movement direction and movement reference unit amount, etc., and based on this recognition information, dimension value from origin to measurement point or measurement point position to measurement point The measurement value such as the moving distance up to is obtained by calculation processing.
In the present invention, the arithmetic processing means may be provided with storage means for preliminarily teaching and storing and storing image information that serves as a comparison determination reference when determining an absolute dimension symbol indicating a dimension value from the origin. good. By configuring in this way, the present invention can also be applied to scales having different absolute dimension symbols.

  In the present invention, it is needless to say that displaying or printing the dimension value or the movement amount of the measurement object can be easily realized by providing the calculation output from the calculation processing means as an input to a known display means or printing means. Yes.

Hereinafter, the present invention will be described in detail with reference to the drawings of an embodiment.
FIG. 1 is an explanatory diagram of the overall schematic configuration of an electronic length / angle measuring instrument according to an embodiment of the present invention. As shown in the figure, the electronic length / angle measuring instrument of the present embodiment includes a measuring unit 4 including a linear scale 1, a slide block 2, an image pickup means 3, and the like, and an arithmetic processing unit 5. .
The arithmetic processing unit 5 includes a CCD / CMOS driving unit 6, an image information setting unit 7, an arithmetic processing unit 8, a storage unit 9, and the like. Further, the measurement value output obtained by the arithmetic processing means is inputted to the display / printing means 10 so that it can be provided as information that can be viewed by the measurer by display or printing.

The linear scale 1 in the present embodiment is made of a metal material and is formed in a straight rail shape, and a scale line 11 having a predetermined width and length is formed along the longitudinal direction of the linear scale 1 on the surface thereof. Are formed at regular intervals. In the present embodiment, as shown in FIG. 2, as the scale line 11, for example, a reference unit scale group 11a in which a scale having a width of 0.1 mm and a length of 4 mm is formed at intervals of 1 mm, a width of 0.1 mm, and a length of 8 mm. The upper unit scale group 11b in which the scales are formed at intervals of 1 cm is formed.
Further, as shown in FIG. 2, for each scale line of the upper unit scale line group 11b, an absolute dimension value symbol 12 indicating a dimension value from the origin to the scale line is associated with a predetermined unit scale line 11b. It is formed within the region range. In the present embodiment, the absolute dimension value symbol 12 is formed by numbers, but may be formed by other figures.

In this embodiment, the imaging means 3 is mounted on the slide block 2 and moves on the linear scale 1 together with the slide block 2 that moves according to the size or movement of the measurement object as described above. It functions to take in the information of the scale line group 11 and the absolute dimension value symbol 12 of the portion facing the imaging means 3 on the surface as electronic image information.
For example, in a state in which the slide block 2 is moved to the measurement point, the imaging unit 3 is driven by the CCD / CMOS driving unit 6 of the arithmetic processing unit 5 and the image information of the imaging region is captured by the CCD / CMOS element of the imaging unit 3. And output to the arithmetic processing means 8.

  The arithmetic processing means 8 processes the image information signal of the graduation line 11 and the absolute dimension value symbol 12 taken from the imaging means 3 via the CCD / CMOS driving means 6, and based on the processing result, the imaging means 3 by using a specific position (for example, the center point) in the field of view 3 as a measurement point, and by determining the position of the measurement point on the scale line 11 group, from the dimension value from the origin of the linear scale 1 or a predetermined measurement start position. Calculate the amount of movement to the measurement position. In this embodiment, the calculation result is output as a measurement value of the dimension or movement amount of the measurement object.

  In the present embodiment, as a premise for performing the above arithmetic processing, the slide block 2 is moved along the rail-like linear scale 1 of the present apparatus, and the image information of each absolute dimension symbol 12 formed on the scale sequentially. And the pattern discrimination information related to each absolute dimension value symbol 12 is taught in advance to the image information setting means 6 of the arithmetic processing unit 9 based on the image information, and stored and saved.

FIG. 3 is a schematic explanatory view of the operation of the image pickup means 3 in the CCD / CMOS element, and schematically shows the relationship between the plurality of graduation lines 11 photographed by the image pickup means 3 and the respective CCD / CMOS elements. Is. As shown in the figure, in this embodiment, the area of the CCD / CMOS element corresponding to the field of view of the image pickup means 3 is composed of a pixel array of N columns × M rows, and the CCD / CMOS drive means 6 Each CCD / CMOS device
(N0, M0) → (N1, M0) → (N2, M0) →... → (Nn, M0) →
(N0, M1) → (N1, M1) → (N1, M0) →... → (Nn, M1) →
・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (Omitted) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ →
(N0, Mm) → (N1, Mm) → (N1, Mm) → (Nn, Mm),
By sequentially scanning, the image information corresponding to the measurement points, graduation lines, and absolute dimension value symbols in the field of view of the imaging means 3 is converted into binary image electronic information and captured.
Actually, there are a plurality of CCD / CMOS elements corresponding to the width of the graduation line, but in FIG. 3, for convenience of explanation, the columns of CCD / CMOS elements corresponding to the graduation lines and measurement points are shown. It is displayed in one column.

In FIG. 3, each image information corresponding to the reference unit scale line includes column Ni-2w, column Ni-w, column Ni + w, column Ni + 2w, column Ni + 3w, column Ni + 4w, column Ni + 5w, column Ni + 6w, column Ni + 7w, column Ni + 8w, It is recognized by the CD / CMOS elements in the range from the Mp row to the Mq row in each CCD / CMOS element group of the column Ni + 9w and the column Nj + w. Here, i is an arbitrary number, j = i + 10w, and w is equivalent to the number of columns of the CCD / CMOS element group existing between the reference unit scale lines. In FIG. 3, the Mp row corresponds to 0 row, the Mq row corresponds to 8 rows, i = 14, and w = 5.
The image information corresponding to the upper unit scale line is recognized by the CCD / CMOS element group in the range from the Mp row to the Mr row in the CCD / CMOS element group of the Ni column and the Nj column. In FIG. 3, the Mr row corresponds to 16 rows.

Further, the absolute dimension value symbol on the scale is formed in a specific region range with respect to the upper unit scale line, and in the example shown in FIG. 3, a CCD / CMOS element corresponding to the tip of the upper unit scale line. Region A having (Ni, Mr) and (Nj, Mr) as base points and (Ni−a, Mr + c) and (Ni + b, Mr + d) as diagonal points, and (Nj−a, Mr + c) and (Nj + b ′) , Mr + d) is configured to recognize the image information of the absolute dimension value symbol by the CCD / CMOS element group in the region B having the diagonal point. Note that b ′ <b. In FIG. 3, the region A is indicated by a region having the pixel (14, 16) as a base point and the pixel (9, 18) and the pixel (19, 27) as diagonal points.
Further, it is assumed that the image information of the measurement point X is recognized by a CCD / CMOS element (Nx.Mx).

In the image information processing means, first, it is determined whether or not the size of the area in which the image information of the absolute dimension value symbol is recognized is normal. That is, in the example shown in FIG. 3, if the area of (a + b) columns × (d−c) rows is a normal range, the area A is determined to be normal, and the area B has a column width of (a + b ') And narrow, so it is judged as an abnormal area.
As described above, the image information in the area A determined to be a normal area is analyzed based on the image information pattern of the absolute dimension value symbol stored in the image information setting unit 7 in advance, and the absolute dimension recognized in the area A The value (numerical value 15 in the example of FIG. 3) is read, and the storage unit stores that the upper unit scale line associated with the absolute dimension value is the upper unit scale line located 15 cm from the origin.

    In the present embodiment, the dimension value from the origin is recognized by the absolute dimension code of the area determined to be a normal area in the field of view of the image pickup means 3 at the time of measurement, but the absolute dimension value formed on the scale When using a scale that does not recognize the absolute dimension value symbol in the normal area within the field of view of the imaging means 3 because the symbol interval is wide, the absolute value dimension value recognized in the normal area is stored in the storage means. Temporarily stored, the number of upper unit scale lines 11b through which the measurement points in the field of view of the camera 3 pass from the start of movement of the imaging means 3 from the measurement point to the arrival of the measurement position is counted, and the movement direction By adding or subtracting correspondingly, the absolute dimension values that are sequentially stored are updated and stored.

Next, two reference graduation lines or upper unit graduation lines that are the first and second closest to the measurement point X (in the example of FIG. 3, the CCD / CMOS element group in the column Ni + 4w and the CCD / CMOS in the column Ni + 5w) The reference scale line recognized by the element group) is recognized.
Of the two recognized scale lines, the scale line on the side close to the upper unit scale line (hereinafter referred to as the starting scale line) including the CCD / CMOS element (Ni, Mr) serving as the base point of the normal region A is By recognizing which reference scale line is counted from the starting scale line, the dimension value from the starting scale line is acquired. For example, in the example of FIG. 3, since it is the fourth reference scale line, it is determined that this dimension value is 4 mm.

  Next, the positional relationship between the two scale lines sandwiching the measurement point X and the measurement point X is recognized, and based on this, the dimension value from the scale line on the side close to the upper unit scale line as the starting scale line Ask for. Although this method will be described in more detail later, basically, the dimension value is determined by recognizing the ratio L1: L2 (where L1 + L2 = 1) of the distance from the measurement point X to the two scale lines. calculate.

In the present invention, a method is adopted in which the distance from the measurement point X to a predetermined number of scale lines is measured for a plurality of ranges, and the dimension value is calculated from the average value of the measurement results.
With this configuration, the present invention absorbs measurement errors due to CCD / CMOS element dimensions and measurement errors due to scale line formation, and can calculate and recognize relatively accurate dimension values. .

  For example, in FIG. 3, the sixth graduation line from the measurement point X is recognized by the CCD / CMOS element array Ni-w on the left side and recognized by the CCD / CMOS element array Nj on the right side. The number of CCD / CMOS element groups between the CCD / CMOS element array Ni-w and the CCD / CMOS element array Nj is (5w + wL1) on the left side and (wL2 + 5w) on the right side. The respective dimensions from the measurement point X to the sixth graduation line are obtained by the product of the number of columns of the CCD / CMOS element group and the pixel size Gd of the CCD / CMOS element.

Next, for example, the distance from the first to the sixth on the left side should be a distance that is five times the reference unit scale, that is, a distance of 5 mm. For example, the distance from the measurement point X on the left to the first scale line However, a temporary measurement value is calculated on the assumption that (5w + wL1) × Gd-5.
Similarly, for example, a temporary measurement value for a plurality of ranges is calculated, such as calculating a similar temporary measurement value based on a measurement value from the measurement point X to the fifth scale line, and the plurality of temporary measurement values are calculated. Is obtained as a measured value.

    The measurement result recognized by the image information processing means 7 as described above is sent to the display / printing means, and is visually recognized by the measurer by displaying or printing.

  FIG. 4 is an explanatory view of a reading example in one embodiment of the electronic length / angle measuring device according to the present invention. As shown in the figure, the scale of the electronic length / angle measuring instrument of the present embodiment is formed with scale lines with irregular intervals, as is clear when compared with an accurate gauge scale indicated by a two-dot chain line. Is.

FIG. 4 illustrates an example in which the movement distance from the position A to the position B is measured using this electronic length / angle measuring device, and in particular, a method for obtaining a measured value of a reference unit or less. Is described with a specific example. In the figure, the absolute dimension value of the upper scale line on the left side is 5 cm, position A is between the 51 mm and 52 mm scale lines, and position B is between the 61 mm and 62 mm scale lines. Is recognized by the above-described method, and details thereof are omitted.
In the present embodiment, a CCD / CMOS element having a pixel size of 14 μm × 14 μm is used, and the measured value by the CCD / CMOS element up to the nth graduation line on both sides of the position A and the position B The measured values by the CCD / CMOS device up to the nth scale line on both sides of the substrate were as follows.

  Temporary measured values Ll ′ and Lr ′ and converted measured values Ll and Lr of the distance to the scale lines on both sides sandwiching the position A or the position B derived from these measured values by the above-described method were as follows. . Moreover, the average value of the conversion measurement value Ll is also shown below.

Measured value from position A to each scale line

Measured value from position B to each scale line

From the above measurement results, the position A is 51.596 mm, the position B is 62. 047 mm, and the actually measured value of the distance between both positions is 10.451 mm.
The result of accurately measuring the distance between the position A and the position B using a gauge is 10.534 mm, and the difference from the measured value by the electronic length / angle measuring instrument of the present invention is 0.083 mm. It can be seen that the electronic length / angle measuring instrument of the present invention is useful.

The invention's effect

  As is apparent from the above description, according to the present invention, an electronic length / angle measuring instrument that measures the size, position, or amount of movement of an object to be measured, wherein the interval between scale lines is formed with high accuracy. Can be measured with relatively high accuracy, even if the scale is not, the cost for forming the scale dimension value from the origin with high accuracy can be saved, and the apparatus can be made inexpensive. An excellent effect is obtained.

FIG. 1 is a schematic configuration explanatory diagram of an electronic length / angle measuring device according to the present invention; Explanatory drawing of the scale line etc. which were formed in the scale surface in the electronic type length / angle measuring instrument of the present invention, The schematic explanatory drawing about image information conversion actions, such as a scale line formed in the scale surface by the CCD / CMOS element in the present invention, Explanatory drawing about the example of a reading in one Example of the electronic type length / angle measuring device by this invention.

Explanation of symbols

1: Linear scale 2: Slide block 3: Imaging unit 4: Measuring unit 5: Arithmetic processing unit 6: CCD / CMOS driving unit 7: Image information setting unit 8: Arithmetic processing unit 9: Storage unit 10: Display / printing unit

Claims (6)

  A scale that forms a scale line group and an absolute dimension symbol group, a slide block that can move relative to the scale in accordance with the dimensions of the measurement object, a scale line group on the scale installed in the slide block, and Imaging means having a CCD / CMOS element for converting information such as absolute dimension symbols into electronic information, CCD / CMOS driving means for driving the imaging means to obtain digitized image information, and the obtained image information An electronic length / angle measuring device having an arithmetic processing means for calculating a dimension value or the like of an object to be measured based on an image of a region associated with a specific graduation line in a visual field by the CCD / CMOS element The information is recognized as image information related to the absolute dimension symbol, and the recognized image information is compared with the image information previously taught and stored in the storage means to determine the absolute dimension symbol. Electronic length / angle measuring device according to claim.   Measure the distance between the measurement points and the scale lines separated by a predetermined number on both sides from the measurement point at different predetermined numbers of points, and measure the distance between the scale lines on both sides sandwiching the measurement points based on the obtained measurement values 2. The electronic length / angle measuring instrument according to claim 1, wherein a measured value of the ratio of the distance to the point is calculated.   3. The electronic length according to claim 1, wherein the imaging means includes a CCD / CMOS element having a region of a size in which two or more absolute dimension symbols are imaged in the field of view. Thickness / angle measuring instrument.   When the scale and slide block move relative to the dimensions of the object to be measured, the scale lines in the field of view are counted by counting the number of scale lines passing through a predetermined position in the field of view by the CCD / CMOS device. 4. The electronic length / angle measuring instrument according to claim 1, wherein the absolute dimension value is recognized.   5. The electronic length / angle measuring instrument according to claim 1, wherein the scale line group is composed of a scale line group based on a plurality of units.   A scale having graduation line groups formed at predetermined intervals; a slide block movable relative to the scale in accordance with the dimension of the measurement object; and an imaging means including a CCD / CMOS element installed on the slide block; , An arithmetic processing means for calculating a dimension value or a moving amount of the measurement object based on the information of the scale line group formed on the scale obtained by the imaging means, and the dimension value and the movement obtained by the arithmetic processing means An electronic length / angle measuring device having storage means for storing quantities, etc., and measuring a plurality of distances between a predetermined number of graduation lines separated from a measurement point on both sides by a predetermined number of points An electronic length / angle measuring instrument that obtains a measurement value of a ratio of a distance between a graduation line on both sides sandwiching the measurement point and the measurement point based on the obtained plurality of measurement values.

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