JP3708270B2 - Electronic level - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic level for automatically identifying a scale value of a collimated scale and obtaining a collimation position.
[0002]
[Prior art]
As the conventional electronic level, for example, according to Japanese Patent Laid-Open No. 5-272970, there are scale patterns arranged at a predetermined pitch in the vertical direction and scale values of one kind of size arranged corresponding to the scale patterns. A telescope that collimates the displayed scale and a two-dimensional sensor that converts an image of the scale collimated by the telescope into an image signal, and the image signal and prestored image data are scaled together. There is known one that identifies a numerical value and automatically calculates a collimation position on a staff.
[0003]
[Problems to be solved by the invention]
In the above conventional apparatus, only one kind of scale value is displayed. Therefore, if the distance to the scale is increased, the scale value in the image signal becomes smaller and cannot be identified. On the other hand, if the scale value displayed on the scale is increased, the scale value is good when the distance to the scale is long. Conversely, when the distance to the scale is short, the scale value cannot be distinguished from the field of view.
[0004]
In view of the above problems, an object of the present invention is to provide an electronic level capable of identifying a scale value regardless of the length of the distance to the scale.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a telescope for collimating a scale on which scale patterns arranged at a predetermined pitch in the vertical direction and scale values arranged in correspondence with the scale patterns are displayed, A two-dimensional sensor that converts an image of a scale collimated by a telescope into an image signal, and automatically identifies the collimated position on the scale by identifying the scale value by combining the image signal and pre-stored image data The first scale pattern in which the scale is arranged at an equally spaced pitch and the first scale value indicating a single-digit large scale value with a different order of distinction in the width direction in the electronic level to be calculated automatically And a second scale pattern arranged at equal intervals with a longer pitch than the first scale pattern, and a second scale value indicating a scale value smaller than the first scale value, and an image Eyes in signal It calculates the distance from the size of the pitch of the pattern to the staff, and determining whether to recognize any size of the scale numeric according to the distance.
[0006]
The scale pattern is displayed at a constant pitch. Therefore, the pitch of the scale pattern in the image signal becomes shorter as the distance to the staff becomes longer, and conversely becomes longer as the distance to the staff becomes shorter. Therefore, if the scale value having the optimum size is identified in accordance with the distance to the internal scale of scale values having different sizes, the scale value can be identified regardless of the length of the distance to the scale.
[0007]
By the way, as a specific means for obtaining the pitch of the scale pattern, it is conceivable to Fourier-transform the image signal along the array direction of the scale pattern. Since the periodic function is expressed as a set of sine waves that are integral multiples of the fundamental frequency by Fourier series expansion, the frequency spectrum is a discontinuous spectrum and the maximum value of the spectrum frequency is high. That is, when the pitch of the scale pattern in the image signal is shortened, the maximum value of the spectrum frequency is increased. Conversely, when the pitch is increased, the maximum value of the frequency is decreased. Therefore, the distance from the maximum value of the frequency to the staff can be obtained.
[0008]
On the other hand, small scale values do not protrude from the field of view regardless of the distance to the scale. Therefore, first, identification processing is performed on a small scale value with priority, and if the small scale value in the image signal is too small to be identified, it is determined that the distance to the scale is long, and a larger scale value is set. You may make it change into identification object.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, reference numeral 1 denotes a telescope, which collimates a staff 2 arranged perpendicular to a front measurement point. The telescope 1 converts the image of the staff 2 into an image signal that is an electrical signal and outputs the image signal to the arithmetic processing unit 3. The electronic level according to the present invention is constituted by the telescope 1 and the arithmetic processing unit 3. In the telescope 1, an eyepiece 11, a focusing lens 12, a compensator 13, a focusing screen 14, and an eyepiece 15 are arranged in this order from the front. It can be done. Although not shown, the focusing lens 12 is provided with a cross-shaped collimation line. In addition, a beam splitter 16 is disposed between the compensator 13 and the focusing screen 14 in the telescope 1, and a CCD camera 17 that is a two-dimensional sensor disposed laterally with respect to the optical axis of the telescope 1. The image of the scale 2 is configured to branch. The CCD camera 17 converts the collimated image of the staff 2 into an image signal, which is an electrical signal, and outputs it to the arithmetic processing unit 3. The image signal from the CCD camera 17 is digitized by the A / D converter 31 and then stored in the image memory 32. In addition to the image memory 32, a ROM 33 and a RAM 34 are connected to the arithmetic processing unit 3 via a bus line with respect to the CPU 30 that performs arithmetic processing. Further, the calculation result in the calculation processing section 3 and the image of the staff 2 are configured to be displayed on the liquid crystal screen 36 via the driver circuit 35. For example, a MOS FET may be used as the two-dimensional sensor in addition to the CCD camera.
[0010]
On the surface of the scale 2, as shown in FIG. 2, scale patterns M1 and M2 arranged at equal intervals in the vertical direction are displayed adjacent to each other. In the present embodiment, the pitch of the scale pattern M1 is set to half the pitch of the scale pattern M2. Also, a three-digit scale value B is displayed on the right side of both scale patterns M1 and M2. The scale value B is 4 mm in the vertical direction and is displayed every 10 mm. For example, the display of 300 indicates that the position is 300 cm from the lower end of the scale 2. A scale value A larger than the scale value B is displayed on the left side. The scale value A has a vertical size of 4 cm, and black scale value AF indicating the order of 10 cm and white scale value AR indicating the order of 1 m are displayed. That is, a white scale value AR of 3 indicates a position of 3 m, and a black scale value AF of 1 marked thereon indicates a position of 3 m10 cm. Such an image of the staff 2 is stored in the image memory 32 as a digitized image signal. The CPU 30 Fourier transforms the image signal along the vertical direction which is the arrangement direction of the scale patterns M1 and M2 in accordance with the arithmetic processing program in the ROM 33. By the way, if a periodic function is Fourier transformed, a high frequency spectrum is obtained, and only a low frequency spectrum is obtained from an aperiodic function. Therefore, as shown in FIG. 3, when the Fourier transform is performed on the portion of the scale pattern M1 having a strong periodicity, a spectrum having a high frequency f1 is obtained. When the Fourier transform is performed on the portion of the scale pattern M2, the pitch is twice, so that a spectrum having a frequency f2 that is 1/2 of f1 is obtained. Since the scale values A and B have low periodicity, only the spectrum of the low frequency group f0 can be obtained. When this Fourier transform is continuously performed on the image signal of the scale 2 from the left to the right sequentially, the maximum value of the spectrum frequency obtained by each Fourier transform is as shown in FIG. As is clear from FIG. 4 , the positions of the scale patterns M1 and M2 can be obtained by repeating the Fourier transform over the full width of the scale 2 in the horizontal direction. When the positions of the scale patterns M1 and M2 are obtained in this way, any one of the scale numerical values A and B and the numerical pattern data stored in the RAM 33 are added to the scale values based on the positions. Character recognition. By the way, if the distance to the scale 2 is long, the pitches of the image signals corresponding to the scale patterns M1 and M2 become fine, so both the frequencies f1 and f2 become high. Conversely, when the distance to the scale 2 is short, the frequency f1 , F2 becomes low. Therefore, the distances from the frequencies f1 and f2 to the staff 2 are obtained, and when the distance is longer than a predetermined distance, the larger scale value A is identified, and when the distance is shorter than the predetermined distance, the smaller scale value is identified. By identifying B, the accuracy of character recognition is increased.
[0011]
As shown in FIG. 5, the collimation position to be finally obtained is the position of the horizontal collimation line K. Therefore, when the scale pattern M1 is used, the pitch P1 (for example, 5 mm) of the scale pattern M1 on the scale 2 is interpolated, and when the scale pattern M2 is used, the pitch P2 of the scale pattern M2 on the scale 2 (for example, 10 mm) is interpolated to determine the dimension L. When the dimension L is 2.5 mm, the collimation position by the collimation line K is obtained as 302.25 cm by adding 2.5 mm to 302 cm identified by automatic reading of the scale value B.
[0012]
In addition to the above-described embodiment, as shown in FIG. 6, the smaller scale value B is preferentially identified without obtaining the distance to the scale 2 (S1), and if it can be identified, refer to FIG. The interpolation calculation process described above is performed (S3), and the height of the collimation position is obtained. If the scale value B cannot be identified because the distance to the scale 2 is long, the identification target may be switched to the scale value A (S2), and then the interpolation calculation process may be performed (S2). S3).
[0013]
【The invention's effect】
As is clear from the above description, according to the present invention, scale values can be identified regardless of the length of the distance to the scale.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a diagram showing an example of display of a scale. FIG. 3 is a diagram showing an example of the maximum frequency of a spectrum obtained by Fourier transform. FIG. 5 is a diagram showing a change in the maximum frequency of the spectrum in the full width in the horizontal direction of the staff. FIG. 5 is a diagram for explaining an interpolation method for obtaining the position of the line of sight. FIG. Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Telescope 2 Standard 3 Operation processing part 17 CCD camera (two-dimensional sensor)
A Scale value B Scale value M1 Scale pattern M2 Scale pattern

Claims (3)

A telescope that collimates a scale on which scale patterns arranged at a predetermined pitch in the vertical direction and scale values arranged corresponding to the scale patterns are displayed, and an image of the scale collimated by the telescope A two-dimensional sensor that converts the signal into an electronic level that identifies the scale value by automatically combining the image signal and pre-stored image data and automatically calculates the collimation position on the scale,
The said scale is longer than this 1st scale pattern and the 1st scale value which displayed the 1st scale value which displayed the large scale value from which an order which can be distinguished differs in the width direction, and the pitch of equal intervals A second scale pattern arranged at equal intervals with a pitch, and a second scale value indicating a scale value smaller than the first scale value,
It calculates the distance from the size of the pitch of the scale pattern in the image signal to staff recognizes the scale value of any magnitude of the first scale values and the second scale numerical depending on the distance An electronic level characterized by determining what. The pre-Symbol image signal, an electronic level according to claim 1, wherein the calculating a distance from the frequency spectrum obtained by Fourier transform to staff in the arrangement direction of the scale pattern. A telescope that collimates a scale on which scale patterns arranged at a predetermined pitch in the vertical direction and scale values arranged corresponding to the scale patterns are displayed, and an image of the scale collimated by the telescope A two-dimensional sensor that converts the signal into an electronic level that identifies the scale value by automatically combining the image signal and pre-stored image data and automatically calculates the collimation position on the scale,
An electronic level characterized in that a plurality of types of scale values of different sizes are displayed on the measuring scale, a small scale value is identified preferentially, and if the identification is impossible, the identification target is changed to a large scale value in order. .

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