JPS6246808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in angle measuring devices such as theodolites that use optical microscopy.

There are various documents regarding theodolites using optical microscopy. Generally, in a theodolite that uses an optical micro, the scale lines on the scale plate are projected by a projection lens so that they line up parallel to the scale lines 180 degrees apart with a slight interval.
The minute angle is calculated from the value read by the optical micro with the index line sandwiched between these two lines, that is, the deflection of the light beam due to the parallel plane, and the angle value on the order of more than the value read by the optical micro is directly displayed on the scale. It is designed to read from the engraved value.

However, when the above-mentioned operation of sandwiching the index line between the two lines and the judgment that the index line is sandwiched in the center are performed by humans, individual errors occur, which cannot be ignored when reading minute angles.

The present invention aims to automate the operation of inserting the index into the center between these two lines, thereby suppressing variations in reading values, and at the same time simplifying the surveying operation. An embodiment of the apparatus according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of the configuration of the apparatus of the present invention. A scale plate 1 in a theodolite or the like has a linear scale part 2 on its outermost periphery, and an absolute encode pattern part 3, which is well-known from an absolute encoder or the like, is drawn inside the linear scale part 2. Illumination light from a light source 4 is guided to the absolute encode pattern section 3 by a fiber bundle 5, and each bit is illuminated. Reference numeral 6 denotes a photodetection element section for each bit, and the rotation angle of the scale plate 1 is converted into, for example, a gray code using a well-known technique.
Here, as a specific example, the minimum amount of angle measurement in absolute encode pattern 3 is 5'
shall be. It is easy to measure this angle absolutely with recent technology. Further, one scale 21 in the linear scale 2 is projected by the prisms 7, 8 and the lens 9 at position 22 so as to be lined up in parallel with the scale 23 at a position 180 degrees apart with a slight interval. The light source 4 is also used to illuminate the vicinity of the scale 21 via the diffuser plate 9.

The two scale lines 22 and 23 lined up on the prism 1
0, an image is formed on the detection surface of the detection unit 17 through the lens 11 and the parallel plane glass 12 forming a part of the optical micro. The reciprocating rotation mechanism of the parallel plane glass 12 has, for example, the following configuration.
The parallel plane glass 12 is supported so as to be rotatable around a rotation axis 13, and is supported by a pulse motor 1.
4 rotation is worm 15 and worm wheel 1
It can be conveyed through 6. The pulse motor 14 rotates forward,
When driven repeatedly in reverse, the parallel plane glass 12 undergoes a reciprocating rotational movement at a certain angle, as shown in FIG.

On the detection surface of the detection section 17, two independent light receiving sections are arranged close to each other. An example of a light receiving element having such a shape is Siemens' differential photodiode: BPX48. Images of the two scale lines 22 and 23 arranged side by side are formed on such a light-receiving element surface, and due to the reciprocating rotational movement of the parallel plane glass 12 described above, the reciprocating movement is made so as to sandwich the boundary between the two light-receiving surfaces. are doing. Since the outputs of the two light-receiving elements are output in a differential manner, the two scale lines 22 and
When image 3 is projected, the output will cross zero. Since the inclination of the parallel plane glass 12 can be converted by the number of pulses applied to the pulse motor 14, the number of pulses applied to the pulse motor 14 when generating the output and zero cross output for the absolute encode pattern 3 (i.e., the number of pulses applied to the parallel The rotational state of the scale plate 1 can be detected from the angle of inclination of the flat glass 12.

Returning to the specific example from earlier, it is necessary for optical microscopy to detect values of 5' or less. Assuming that the linear scale part 2 on the scale plate 1 is drawn centered on a diameter of 90.8 mm, the interval with respect to the 5' angle is approximately 66 μm. This amount of deflection of 66 μm is caused by the inclination of the parallel plane 12.

Runout amount: δ≒n-1/n・d・tanα n; refractive index of parallel plane glass d; Thickness of parallel plane glass α; Tilt angle of parallel plane glass Because it is expressed as If n=1.52, d=2mm, δ=66μm α≒330′ becomes.

For example, when the pulse motor 14 rotates 0.9 degrees per pulse, and the parallel plane glass 12 is tilted 360' when the pulse motor 14 rotates 400 pulses or 360 degrees, the pitch of the worm 15 and the worm wheel 1
This is executed by adjusting the radius value in step 6. The angle corresponding to one pulse of the pulse motor is calculated to be 0.75''.Each value in the specific example described here is shown as an example to realize the device according to the present invention, and other design examples may be used. It is clear that various realizations can be made.In addition to the reciprocating rotational movement of the parallel plane glass 12, the same effect can be obtained by rotating the parallel plane glass 12, but in this case, an unnecessary rotating part is also generated, resulting in a time loss. It is also clear that the configuration example described in FIG. 1 can be used for both horizontal and vertical angle measurements in a theodolite or the like.

FIG. 2 shows an example of the configuration of the angle detection circuit section of the device according to the present invention. First, the microprocessor 35 starts the pulse motor 1 as an initial operation.
The pulse motor drive circuit 36 is operated so that 4 is at the reference position. The reference position of the pulse motor 14 is set, for example, when the parallel plane glass reaches its maximum angle with respect to the dial, and this state is detected by the pulse motor reference position detection circuit 37.

Although a specific example of detecting whether the shaft of the pulse motor 14 is at a certain reference position is not shown in FIG. 1, it is easily possible using various well-known techniques. For example, there is a method of attaching a rotating disk having a thin slit to the shaft of the pulse motor 14, placing a transmission type photo coupler between the rotating disks, and detecting a predetermined position (reference position).

Thereafter, the microprocessor 35 drives the pulse motor drive circuit 36 to provide pulses in a predetermined rotational direction to the pulse motor 14, and outputs the pulses through the detection element 31, the differential amplifier 32, and the zero-cross detection circuit 33. monitor the zero-cross output. Then, based on the number of pulses given to the pulse motor 14 and the input from the absolute encode pattern to gray code exchange circuit 34 at the time when the zero cross output is output, the angle information of the scale plate at that time is stored. Then, return the parallel plane glass to the standard position again.

After the scale rotates, the same sequence as above is used to detect and store the angle information of the scale.
The rotation angle is calculated by comparing it with the previous information, and the result is displayed on the display circuit section 38. The configuration of the angle detection circuit section shown in FIG. 2 can be applied to both horizontal and vertical angle detection.

As described above, the angle measuring device according to the present invention automates the operation of sandwiching two scale lines facing each other at 180 degrees, thereby suppressing variations in reading errors and simplifying the angle measuring operation. This is particularly effective for high-precision angle measurement.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of the device of the present invention, and FIG.
The figure shows a configuration example of an angle detection circuit. 1: Scale plate, 2: Linear scale section, 3: Absolute encode pattern section, 4: Light source, 5: Fiber bundle, 6: Photodetection element section, 7, 8: Prism, 9: Lens, 10: Prism, 11: Lens, 12: Parallel plane glass, 13: Rotation axis, 1
4: Pulse motor, 15: Worm, 16: Worm wheel, 31: Detection element, 32: Differential amplifier, 33: Zero cross detection circuit, 34: Absolute encode pattern to Gray code conversion circuit, 35: Microprocessor, 36: Pulse motor drive circuit, 37: Pulse motor reference position detection circuit, 38: Display circuit section.

Claims (1)

[Scope of Claims] 1. In an angle measurement device such as a theodolite having an optical micro, an optical system that projects the scale lines of a scale board close to a scale line at a position 180 degrees apart, and a parallel a reciprocating rotation mechanism section using a pulse motor that rotates the plane glass back and forth; and a detection section that detects that the two scale lines are projected at a predetermined position through refraction of the parallel plane glass that rotates back and forth. and an angle detection circuit section that detects the amount of inclination of the flat glass at the time of detection by counting the drive pulses of the pulse motor, and calculates angle information from the amount of inclination. Angle measuring device with. 2. The reciprocating rotating optical system according to claim 1, wherein the detecting section has a configuration in which two independent light receiving sections are arranged close to each other and outputs a differential output of the light receiving element output of each light receiving section. Angle measuring device with micro.