JPS6348408A - Angle measuring instrument - Google Patents

Abstract

PURPOSE:To take an accurate measurement without any error even if a light emitting device shifts in installation position around an optical axis by installing the light emitting device and a light receiving device on a base surface to be measured and emitting a circular polarized light beam by the light emitting device. CONSTITUTION:The light emitting device 4 which emits the circular polarized light beam and the light receiving device 5 are provided along the base surface 2. The beam splitting plate 11 of the light receiving device 5 transmits part 7a of the incident light beam 7 and reflects the remainder 7b. Then the light beam 7a is reflected totally by a reflecting plate 12 and made incident on the 2nd coordinate detecting means 14 to find the two-dimensional coordinates of the incidence point. Further, the light beam 7b is made incident on the 1st coordinate detecting means 13 to find the two-dimensional coordinates of the incidence point. An arithmetic display device 6 calculates and displays the angle between both base surfaces based by using the incidence point coordinates found by a 1st and a 2nd coordinate detecting means 13 and 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an angle measuring device, and relates to an angle measuring device suitable for use, for example, in measuring the joint angle of a propeller shaft of a vehicle.

[Prior Art] A vehicle drive system includes an engine, a propeller shaft, a differential gear (hereinafter referred to as a differential), and the like, each of which has a rotating shaft. These shafts are connected to each other by a Fuchs joint and have a defined joint angle at the connection. It is well known that this joint angle is related to the noise generated from the drive system.

For this reason, it is important to measure the joint angle. A device that uses the Doppler effect of laser light is known as a device that precisely measures angles, but this method cannot measure the absolute value of the angle, and only measures the relative displacement angle, which is how much the angle has changed. Therefore, it was not suitable for measuring joint angles. Therefore, the joint angle is currently measured using a spirit level, protractor, etc.
This method has the drawbacks of poor accuracy and reproducibility, and a large number of measurement steps. Therefore, a method for measuring the joint angle simply and accurately has been desired.

The present invention has been made in view of such demands, and an object of the present invention is to provide an angle measuring device that can measure joint angles and the like easily and with high precision.

[Means for Solving the Problems] The configuration of the present invention will be explained with reference to FIGS. It is provided with a light emitter 4 that emits a light beam 7 parallel to the surface 2, and a light receiver 5 provided on the other base surface 1 and allowing the light beam to enter therein. The light emitter 4
is equipped with a light emitting means for emitting a circularly polarized light beam. The light receiver 5 also includes the light beam 7 that is incident on the plate surface.
A beam splitter plate 11 is provided behind and parallel to the beam splitter plate 11 to allow the light beam to pass through the beam splitter plate 11 and to reflect the remaining part 7b in a direction different from the incident direction. a reflector plate 12 that totally reflects the beam 7a; and the beam splitter plate 1.
a first coordinate detecting means 13 that allows the light ray 7b reflected by the reflector plate 12 to enter therein and outputs the two-dimensional coordinates of the point of incidence; a second coordinate detecting means 14, and a calculation display means 6 for calculating and displaying the angle formed by the side base surface from the incident point coordinates obtained in step 3.14; It is mandatory to have the following.

[Effect] According to the angle measuring device having the above configuration, the angle formed by the side base surface can be easily and highly accurately measured by simply installing the light emitter 4 and the light receiver 5 on each of the base surfaces to be measured. .

In the device of the present invention, since the light emitter 4 emits circularly polarized light, accurate measurements can be made without causing errors even if the installation position of the light emitter 4 changes around the optical axis. be.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to joint angle measurement of a propeller shaft of an automobile. Reference numerals 1 and 2 denote a propeller shaft driven by an engine (not shown in the drawing), which is divided into two parts by a footer joint 3. The central axes of the propeller shafts 1 and 2 are not on a straight line, and are generally connected at a joint angle θ of 10 degrees or less. Reference numeral 4 denotes a light emitter installed on the propeller shaft 2, which emits a light beam 7 parallel to the central axis of the propeller shaft 2, which is one base surface. Reference numeral 5 denotes a light receiver installed on the propeller shaft 1, which is the other base surface, and has a reference axis 5a, and the central axis of the propeller shaft 1 and the reference axis 5a are parallel. the above,
The light receiver 5 is connected to an external angle calculation display 6,
The calculation display 6 inputs the output signal of the light receiver 5 and calculates and displays the joint angle θ.

FIG. 2 shows a perspective view of the light emitter 4. As shown in FIG. The light emitter 4 is a substantially rectangular parallelepiped case 45 polished so that each surface is at right angles.
The case 45 includes a laser diode 41, a collimator lens 42, and a linear polarizer 4 along its long axis.
3 is installed.

The laser diode 41 is driven to emit light by a drive circuit 44.

The laser light emitted from the laser diode 41 generally has linear polarization, and since there is a spread angle of the light beam, the collimator lens 42 converts it into parallel light.

The polarization state of the light rays coming out of the collimator lens does not change,
It becomes linearly polarized light. The light beam that has passed through the collimator lens 42 passes through a linear polarizer 43. The linear polarizer 43 is a quarter-wave plate, and the angle that its optical axis makes with the polarization plane of the incident linearly polarized light is 45. If the polarizer 43 is set at a certain angle, the light passing through the linear polarizer 43 becomes circularly polarized light without a plane of polarization.

The case 45 has V grooves 4a on the bottom and side surfaces respectively.
, 4b are formed, and the above-mentioned groove 4a is formed by a built-in magnet.
, 4b are suction-fixed to the propeller shaft 2. As shown in the figure, when the light emitting device 4 is fixed to the propeller shaft 2 with the groove 4a, the light beam 7 emitted from the light emitter 4 becomes parallel to the axis of the propeller shaft 2. This light beam 7 is incident on a light receiver 5 provided on the propeller shaft 1 (FIG. 1).

FIG. 3 is a sectional view showing the structure of the light receiver 5 shown in FIG. 1. Like the light emitter 4 shown in FIG. It is. In Fig. 3, 7 is the incident light, 10 is a filter that passes only the wavelength of the incident light 7 and cuts out disturbance light, and 11 is a beam splitter that reflects a part of the incident light 7 and outputs reflected light 7b. A part of the incident light 7 is transmitted along with the transmitted light 7a.
Output. A reflecting mirror 12 reflects the transmitted light 7a.

13 and 14 are incident position detectors that emit coordinate signals according to the two-dimensional incident point coordinates of the incident light, and position sensing detectors (for example, Hamamatsu Photonics)
31300) manufactured by Co., Ltd. can be used. Incident position detector 1
3 and 14 are provided to face the beam splitter 11 and the reflecting mirror 12, respectively, as shown, and determine the positions of the incident points of the reflected light 7b and the transmitted light 7a of the beam splitter 11, respectively. 15 is the incident position detector 13 and 1
This is a printed circuit board that includes a head amplifier circuit that processes the output signals of No. 4.

FIG. 4 shows the configuration of the head amplifier circuit 15 shown in FIG. 3, in which the same processing circuits 15a115b are provided independently for the incident position detectors 13 and 14. 151a, 152a, 153a, in the processing circuit 15a,
154a is a known current-voltage conversion circuit made up of a resistor and an operational amplifier, and 155a and 156a are subtraction circuits made up of a resistor and an operational amplifier. With this processing circuit 15a,
8 signals 131a, 131b, 1 forming coordinate signal @131
31c and 131d are converted into voltage signals and output.

Similarly, 141a, 141b, 141c, and 141d constituting the coordinate signal 141 of the incident position detector 14 are the processing circuit 1.
A processing circuit 15b having the same circuit configuration as 5a converts it into a voltage signal and outputs it.

FIG. 5 shows the configuration of the calculation display 6 shown in FIG. 1, and 61 and 62 are amplifiers A having the same circuit configuration.
and amplifier B, the configurations of which are omitted because they are known, have four channels of known non-inverting amplification circuits using operational amplifiers, and a processing circuit 1 which is the output coordinate signal of the detection unit 5.
The output signals of 5a and 15b (FIG. 4) are each amplified. A switch 63 determines the sampling timing of the output coordinate signal of the detection unit 5. Reference numeral 64 is a sample and hold circuit, and its configuration is omitted because it is well known, but for example, the SHM-
The configuration is such that eight iC-1s are used to simultaneously sample and hold eight channels of voltage signals. The sample timing is determined by the signal from the switch 63, and the output signal from the sample hold circuit 64 is determined by the incident position detector 13 at the time when the switch 63 is turned on.
and 14 coordinates are output. 65 is a multiplexer, for example, a well-known multiplexer (Dichiru Corporation ¥JJMX
-808> is used. The multiplexer 65 selects and outputs one signal from the eight output signals of the sample and hold circuit. 66 is a known A/D converter circuit, for example, a 12-bit A/D converter (ADC80-
AGl 2> is used. 67, 68, and 69 each constitute a microcomputer, and 67 is a CPU;
68 is a ROM, 69 is a RAM, and a pass line 611
connected with. In this embodiment, the CPU 67 uses an 8-bit CPtJ (HD68 newly manufactured by Hitachi, Ltd.).
03). Further, a signal from the switch 63 is input as an interrupt signal. The ROM 68 stores in advance an arithmetic processing program in the form of machine code. RAM69
is a work area for executing a program stored in the ROM 68. A display 610 displays the calculated joint angle θ.

Next, the program stored in the ROM 68 shown in FIG. 5 will be explained with reference to the flowchart shown in FIG.

The program consists of two routines, as shown in Figure 6 (
1) is an initial routine, and FIG. 6(2) is an interrupt routine. The initial routine is a routine that is activated when the power is turned on, and first performs memory initialization and the like in step S1. Next, the display is cleared in step S2, and interrupts are permitted in step S3. Thereafter, step S3 is repeated to wait for an interrupt. Figure 6 (2
) is a υ1 entry routine, which starts execution when the above-mentioned initial routine executes step S3 and the switch 63 is turned on.

First, in step 11, disable its own interrupts, and then in step 12, change the channel of the multiplexer 65 to CH.
Set to l. Next, in step i3, channel CH1
Read analog data as A/D data into RAM
69 at a specific address. Next, in step i4, the multiplexer 65 is set to the next channel CH2. In step i5, it is determined whether 8 channels of data have been read, and if 8 channels have not been completed, the result is N.

Then, the process returns to step i3. After going through this loop 8 times, 8 channels of data (CH1 to CH8 data) have been read and stored in memory, and step i
Proceed to step 6. In step i6, channels CH1 to CH
4, the incident coordinates P (Xl, Yl) of the incident position detector 14 are calculated. Further step 1
7, the coordinates Q x
゜Y2) is calculated.

Coordinates P and Q are calculated as follows.

The CH2-CH2 data are each XIA=XIB.

When YIA and YIB are set and the data of Cl-15 to CH8 are respectively set as X2A=X2B-Y2A=Y2B, it is obtained from the following formula.

P(Xl, Yl)=Q(X2.Y2)- Here, L is the incident position detector 13. This is the maximum value that the coordinates of '14 can take.

Roughly step; 8, step i5. The joint angle θ is calculated from the coordinates of P and Q determined in i7. The calculation formula is as follows.

Here, d is the distance between the incident position detector 13 and the coordinate origin of ]4.

When measuring the joint angle θ with the angle measuring device configured as described above, the light emitter 4 is fixed to the propeller shaft 2 by suction. At this time, the light beam 7 from the light emitter 4 is transmitted to the propeller shaft 2.
parallel to the central axis of A light receiver 5 is suctioned and fixed onto the other propeller shaft 1 via the Fuchs joint 3.

At this time, the light receiver 5 is appropriately positioned and provided so that the incident light beam to the light receiver 5 falls within the effective coordinates of the built-in incident position detectors 13 and 14. Although not described in detail in this embodiment, it is determined whether the output of the multiplexer is below a certain level to determine whether it has entered the effective coordinates, and if it is below a certain level, it is determined that no light is entering. can.

Then, when the switch 63 is pressed, the joint angle θ is displayed on the display 610.

By the way, when a linearly polarized light beam is used for measurement, interference at the beam splitter 11 causes the light emitter 4 to
Errors may occur if the installation position changes. On the other hand, in the present invention, since a circularly polarized light beam is used for measurement, no error occurs depending on the installation position of the light emitter 4, and accurate measurement is possible.

[Brief explanation of drawings]

Figure 1 is a device configuration diagram showing an example in which an angle measuring device is provided on the propeller shaft of a vehicle, Figure 2 is a perspective view of a light emitter, and Figure 3 is a perspective view of a light emitter.
4 is a circuit diagram of a head amplifier circuit, FIG. 5 is a circuit diagram of a calculation display, and FIG. 6 is a program flow chart. 1.2... Propeller shaft (base) 4...
... Emitter 41 ... Laser diode 42 ... Collimator lens 43 ... Linear polarizer 5 ... Light receiver 11 ... Beam Splitter plate 12...Reflector plate 13...Incidence position detector (first coordinate detection means) 14...Incidence position detector (second coordinate detection means) 6・・・・・・Calculation display 1st page, Figure 4, Figure 6, (1)

Claims (2)

[Claims] (1) A light emitter that is provided on one of a pair of base surfaces that are at an angle to each other and emits a ray of light parallel to the base surface, and a light receiver that is provided on the other of the base surfaces that allows the light ray to enter. The light emitter is equipped with a light emitting means that emits a circularly polarized light beam, and the light receiver is configured to allow a part of the light beam incident on the plate surface to pass therethrough and direct the remaining part in the direction of incidence. a beam splitter plate that reflects the beam in a different direction from the beam splitter plate, a reflecting plate that is provided behind and parallel to the beam splitter plate and totally reflects the light beam after passing through the beam splitter plate, and a reflector plate that reflects the light beam reflected by the beam splitter plate. a first coordinate detecting means for inputting the light beam and outputting the two-dimensional coordinates of the incident point; and a second coordinate detecting means for inputting the light beam reflected by the reflecting plate and outputting the two-dimensional coordinates of the incident point.
and an arithmetic display means for calculating and displaying the angle formed by the two base surfaces from the incident point coordinates obtained by the first and second coordinate detecting means, respectively. Angle measuring device. (2) The light emitting means includes a laser diode that emits linearly polarized laser light, and a quarter-wavelength laser diode that is provided in front of the laser diode and whose optical axis is set at 45 degrees with respect to the polarization plane of the laser light. An angle measuring device according to claim 1, comprising a linear polarizer made of a plate.