JP2007218722A - Tilt angle sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of a tilt angle sensor by using a general-purpose light receiving element for the angle detector. <P>SOLUTION: The tilt angle sensor includes a bubble tube 1, a light emitting part 6 placed below the bubble tube, a light receiving element 30 placed above the bubble tube, and an operation part 17 calculating a tilt angle from an output of the receiving element. A mask pattern 20 is disposed between the bubble tube and the receiving element. On the mask pattern, four position detecting light passage windows are disposed in a radial and crucial form while a reference light passage window is disposed in the vicinity of a radial outer end of each position detecting light passage window. The receiving element comprises four two-piece photodetectors. Two light receiving parts of each two-piece photodetector are disposed at positions corresponding to a position detecting light passage window and a reference light passage window, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tilt angle detector that extracts a tilt angle as an electrical signal.

  The electronic surveying instrument is provided with a tilt angle detector that extracts the tilt angle as an electrical signal. As such an inclination angle detector, the one described in Patent Document 1 below is known.

  An inclination angle detector described in Patent Document 1 shown below is shown in FIGS. As shown in FIG. 7, this inclination angle detector is one in which bubbles 4 are enclosed in a circular bubble tube 1 in which a transparent liquid 5 is enclosed. In order to take out the inclination angle as an electric signal, the bubble tube 1 Is provided with a light emitting portion 6 that emits a parallel light beam 3, and a light receiving element 9 is provided above the bubble tube 1. The light emitting unit 6 includes a light source 7 such as an LED and a collimator lens 8 that converts light emitted from the light source 7 into parallel rays. As shown in FIG. 8, the light receiving element 9 includes four position detecting light receiving units 13, 14, 15, and 16 on the X and Y axes of the XY coordinates with the origin coincided with the center O in a cross-shaped radial shape. And a reference light receiving portion 12. The outputs of these light receiving units 12, 13, 14, 15, 16 are input to the calculation unit 17.

  The parallel light beam 3 emitted from the light emitting unit 6 passes through the transparent liquid 5 in the bubble tube 1 and enters the light receiving element 9, but is reflected by the bubble 4, and the bubble 4 casts a shadow 10 on the light receiving element 9. It is like that. The reference light receiving portion 12 of the light receiving element 9 is disposed at a position that does not cover the shadow 10 of the bubble 4. When the bubble tube 1 is horizontal, the center of the shadow 10 of the bubble 4 is positioned at the center O of the light receiving element 9 as shown by the broken line in FIG. Since the same amount of light is incident on 15 and 16 and the four position detection light-receiving units 13, 14, 15 and 16 output equal electric signals, the calculation unit 17 can determine that the bubble tube 1 is horizontal. When the bubble tube 1 is tilted, the bubble 4 moves, and the shadow 10 of the bubble 4 also moves as shown by the solid line in FIG. 8, so that the electric power output from each position detection light-receiving unit 13, 14, 15, 16 Since the signals change individually, the calculation unit 17 can calculate the tilt angle in the biaxial direction based on the output difference between the pair of position detection light receiving units 13 and 14, 15 and 16. .

That is, the inclination angle θx in the X-axis direction and the inclination angle θy in the Y-axis direction of the inclination angle detector in FIG. 8 are R for the radius of curvature of the upper surface of the bubble tube 1, and the position detection light receiving units 13, 14, 15, 16. , The reference light receiving unit 12 area is S ₁₂ , the reference light receiving unit 12 output is V ₁₂ , and the position detection light receiving units ₁₃ , ₁₄ , 15, 16 output are V ₁₃ , V ₁₄ , V, respectively. _{Assuming 15} and V ₁₆ , the following equations (1) and (2) are obtained, respectively.
θx = {S ₁₂ / (2DR)} {(V ₁₃ −V ₁₄ ) / V ₁₂ } (1)
θy = {S ₁₂ / (2DR)} {(V ₁₅ −V ₁₆ ) / V ₁₂ } (2)

When calculating the tilt angles θx and θy, reference is made to the output differences (V ₁₃ −V ₁₄ ) and (V ₁₅ −V ₁₆ ) of the paired position detection light receiving units 13 and 14, 15 and 16. The reason for dividing by the output V ₁₂ of the light receiving unit 12 is to remove an error in the tilt angle caused by expansion of the bubble 4 due to temperature change, sensitivity change of the light receiving element 9, and the like.

  As shown in FIG. 9, four reference light receiving sections 12 may be provided close to the radial outer ends of the respective position detection light receiving sections 13, 14, 15, and 16.

Japanese Patent No. 2655276

  The light receiving element 9 described in Patent Document 1 has a special shape in which the four position detecting light receiving portions 13, 14, 15, and 16 are arranged in a cross-shaped radial shape and also includes a reference light receiving portion 12. Therefore, a general-purpose light receiving element cannot be used, and a custom-made product is used. For this reason, there is a problem that the light receiving element 9 is expensive and the price of the tilt angle detector is also expensive.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the cost of the tilt angle detector by using a general-purpose light receiving element for the tilt angle detector.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a bubble tube, a light emitting unit disposed below the bubble tube, a light receiving element disposed above the bubble tube, and an output of the light receiving element. In the inclination angle detector including the calculation unit for calculating the inclination angle from the mask tube, a mask pattern is disposed between the bubble tube and the light receiving element, and the mask pattern includes four position detection light passage windows. The reference light passage window is arranged in the vicinity of the radial direction outer end of each position detection light passage window, and the light receiving element has four two-split photodetectors, and each of the two split light detections. The two light receiving portions of the detector are arranged at positions corresponding to the position detection light passage window and the reference light passage window, respectively.

  According to a second aspect of the present invention, there is provided a bubble tube, a light emitting unit disposed below the bubble tube, a light receiving element disposed above the bubble tube, and an operation for calculating an inclination angle from an output of the light receiving element. In a tilt angle detector provided with a liquid crystal part, a liquid crystal mask pattern is disposed between the bubble tube and the light receiving element, and in accordance with a command from the arithmetic unit, the mask pattern is disposed in a cross-shaped radial pattern. Four position detection light passage windows and a reference light passage window arranged in the vicinity of the radially outer end of the position detection light passage window are alternately formed in time, and the light receiving element has four light receiving portions. Each light receiving portion is arranged at a position corresponding to the position detection light passage window and the reference light passage window.

  According to the tilt angle detector of the first aspect of the present invention, it is possible to configure a light receiving element from a general-purpose two-divided photodetector, and it is not necessary to use a custom-made light receiving element. The cost of the detector can be reduced.

  According to the tilt angle detector of the second aspect of the present invention, it becomes possible to configure a light receiving element from a general-purpose quadrant photodetector or four photodetectors, and a custom-made light receiving element is not used. Therefore, the cost of the tilt angle detector can be reduced.

  Hereinafter, a first embodiment of the tilt angle detector of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of the tilt angle detector. FIG. 2 is a plan view of a mask pattern of the tilt angle detector. FIG. 3 is a plan view of a light receiving element of the tilt angle detector. FIG. 4 is a plan view of a two-divided photodetector constituting the light receiving element.

  This tilt angle detector includes the conventional tilt angle detector shown in FIGS. 7 to 9 and a mask pattern 20 disposed between the bubble tube 1 and the light receiving element 30 as shown in FIG. 3 and FIG. 4, except that the structure of the light receiving element 30 is different. Accordingly, in FIG. 1, the same reference numerals as those in FIG. 7 are assigned to the same portions of the tilt angle detector as in the prior art, and further description thereof is omitted. Hereinafter, portions different from the prior art will be described.

  The mask pattern 20 is made of glass. A metal film is deposited on the surface of the mask pattern 20 to block light, and a window through which light can pass is formed by etching. As the metal film, chromium, chromium oxide or the like is used. As shown in FIG. 2, the mask pattern 20 includes four position detection light passage windows 23, 24 that are long along the X axis and the Y axis of the XY coordinates whose origin is coincident with the center O. 25 and 26 are arranged in a cross-shaped radial shape, and a short reference light passage window 22 is arranged in the vicinity of the radially outer ends of the position detection light passage windows 23, 24, 25 and 26. The inner ends in the radial direction of the four position detection light passage windows 23, 24, 25, 26 are separated from the center O of the mask pattern 20 by a predetermined distance. The position detection light passage windows 23, 24, 25, and 26 and the reference light passage window 22 are made by depositing a metal such as chromium oxide on a glass plate and etching the metal film in each of the windows 23, 24, 25, 26, and 22 portions. It is formed by removing. Of course, the mask pattern 20 may be a metal plate, and the plate may be cut to form the windows 23, 24, 25, 26, 22 or a liquid crystal mask pattern. In this case, the mask pattern can be formed by a conventional technique.

  As shown in FIG. 4, the light receiving element 30 includes a two-part photodetector 38, which is a general-purpose product having two light receiving portions 33, 34, 35, 36, and 32, which are long and short, as shown in FIG. They are arranged at positions corresponding to the passing windows 23, 24, 25, 26 and the reference light passing window 22. Each of the two-divided light detectors 38 is positioned at positions corresponding to the position detection light passage windows 23, 24, 25, 26 and the reference light passage window 22, and the position detection light receivers 33, 34, 35, 36 and the reference light. It is installed so that the light receiving part 32 is located. The position detection light receivers 33, 34, 35, and 36 and the reference light receiver 32 are slightly larger in width and length than the position detection light passage windows 23, 24, 25, and 26 and the reference light passage window 22. . For this reason, the parallel light beam 3 emitted from the light emitting unit 6 passes through the position detection light passage windows 23, 24, 25, 26 and the reference light passage window 22 of the mask pattern 20 and receives the position detection light of the light receiving element 30. Light images 43, 44, 45, 46, 42 are generated on the parts 33, 34, 35, 36 and the reference light receiving part 32 so as not to protrude from them.

When the bubble tube 1 is horizontal, the center of the shadow 10 of the bubble 4 is located at the center O of the mask pattern 20, and the parallel rays 3 that have passed through the position detection light passage windows 23, 24, 25, 26 are at four positions. Since the detection light receiving units 33, 34, 35, and 36 are irradiated with the same area, and the same electrical signals are output from the four position detection light receiving units 33, 34, 35, and 36, the calculation unit 17 is the bubble tube 1 Can be judged to be horizontal. When the bubble tube 1 is inclined and the position of the bubble 4 is moved, the shadow 10 of the bubble 4 is also moved, and the received light amounts of the position detection light receiving units 33, 34, 35, and 36 are individually changed. The calculation unit 17 standardizes the outputs of the two-part photodetectors 38 by dividing the outputs of the position detection light receiving units 33, 34, 35, 36 by the outputs of the respective reference light receiving units 32. Based on the difference between the standardized outputs of the position detection light receivers 33 and 34 and 35 and 36 that form a pair of inclination angle detectors, the following equations (3) and (4) are used to The tilt angles θx and θy in the biaxial direction of the angle detector can be calculated.
_{θx = {S 12 / (2DR} )} (V 13 / V 12 (13) -V 14 / V 12 (14)) (3)
_{θy = {S 12 / (2DR} )} (V 15 / V 12 (15) -V 16 / V 12 (16)) (4)

However, in the expressions (3) and (4), one area of the reference light transmitting window 22 in S _12, the radius of curvature of the upper surface of the bubble tube 1 to R, the position detection light passes the D The widths of the windows 23, 24, 25, 26 are set to V ₁₃ , V ₁₄ , V ₁₅ , V _16, and the outputs of the position detection light receiving units 33, 34, 35, 36 are respectively set to V _{12 (13)} , V _{12 (14)} , V12 ₍₁₅₎ , and V12 ₍₁₆₎ use the output of the reference light receiving unit 32 of each two-part photodetector 38.

  According to the present embodiment, the light receiving element 30 can be configured from the general-purpose two-divided photodetector 38, and it is not necessary to use a custom-made light receiving element, so that the cost of the inclination angle detector can be reduced. can do.

  Next, a second embodiment of the tilt angle detector of the present invention will be described. FIG. 5 is a plan view of a mask pattern of the tilt angle detector. FIG. 6 is a plan view of a light receiving element of the tilt angle detector. The tilt angle detector of the present embodiment is the same as the first embodiment except that the mask pattern 50 and the light receiving element 60 are different from the first embodiment.

  The mask pattern 50 is formed of a liquid crystal panel that is normally opaque and becomes transparent when a control voltage is applied. In response to a command from the calculation unit 17 (see FIG. 1), four position detection light passages indicated by solid lines in FIG. The windows 53, 54, 55, 56, 52 can be opened and closed by switching the windows 53, 54, 55, 56 and the four reference light passage windows 52 indicated by the wavy lines alternately in time to be transparent. It is what.

  The light receiving element 60 uses a general-purpose quadrant photodetector. The light receiving element 60 is divided into four fan-shaped light receiving portions 63, 64, 65, 66 having a central angle of 90 °, and each position detection light passing window 53, 54, 55, 56 of the mask pattern 50 and reference light. Corresponding to the positions of the passage windows 52, the respective light receiving portions 63, 64, 65, 66 of the four-divided photodetector are arranged.

  When detecting the tilt angle, the parallel light beam 3 is emitted from the light emitting unit 6, and first, only the four position detection light passage windows 53, 54, 55, and 56 are opened by a command from the calculation unit 17. Then, light images 73, 74, 75, and 76 are generated in the respective light receiving portions 63, 64, 65, and 66 of the light receiving element 60 by the parallel light beam 3 that has passed through the position detection light passage windows 53, 54, 55, and 56. . Here, the calculation unit 17 reads the outputs of the light receiving units 63, 64, 65, 66. Next, the four position detection light passage windows 53, 54, 55, and 56 are closed and the four reference light passage windows 52 are opened according to a command from the calculation unit 17. Then, in each of the light receiving portions 63, 64, 65 and 66 of the light receiving element 60, a light image 72 is generated by the parallel light beam 3 that has passed through the position detection light passage window 52. Here, the calculating part 17 reads the output of each light-receiving part 63,64,65,66. Of course, the order of opening and closing the position detection light passage windows 53, 54, 55 and 56 and the reference light passage window 52 may be reversed.

Thus, when the position detection light passage windows 53, 54, 55, and 56 and the reference light passage window 52 are opened and closed alternately in time, each of the position detection light passage windows 53, 54, 55, and 56 is opened. The outputs of the respective light receiving portions 63, 64, 65, 66 when only the reference light passage window 52 is opened can be read alternately. As in the first embodiment, the tilt angles θx and θy in the biaxial direction of the tilt angle detector can be calculated using the equations (3) and (4). However, in the above formulas (3) and (4), S ₁₂ is the area of one reference light transmission window 52, D is the width of the position detection light passage windows 53, 54, 55, 56, V ₁₃ , V ₁₄ , V ₁₅ , and V ₁₆ are outputs of the light receiving units 63, 64, 65, and 66 when the reference light passage window 52 is closed and the position detection light passage windows 53, 54, 55, and 56 are opened, respectively. V _{12 (13)} , V _{12 (14)} , V _{12 (15)} , and V _{12 (16)} are respectively when the position detection light passage windows 53, 54, 55, and 56 are closed and the reference light passage window 52 is opened. The outputs of the light receiving units 63, 64, 65, and 66 are used.

  Also in this embodiment, the light receiving element 60 can be configured from a general-purpose four-divided light detector, and it is not necessary to use a custom-made light receiving element, so that the cost of the tilt angle detector can be reduced. it can.

  By the way, the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, although the present invention is applied to a circular bubble tube in the above embodiment, the present invention can also be applied to a rod-shaped bubble tube. In the second embodiment, the light receiving element 60 is constituted by a four-divided photodetector. However, four photodetectors having only one light receiving portion may be used. In the configuration of FIG. 1, the entire bubble 1 tube is illuminated by one light source 7, but a pair of ranges of the position detection light passage windows 23, 24, 25, and 26 and the reference light passage window 22 are illuminated. Thus, four light sources may be arranged.

It is a longitudinal cross-sectional view of the inclination angle detector which concerns on 1st Example of this invention. It is a top view of the mask pattern of the said inclination angle detector. It is a top view of the light receiving element of the said inclination angle detector. It is a top view of the 2 split photodetector which comprises the said light receiving element. It is a top view of the mask pattern of the inclination angle detector which concerns on 2nd Example of this invention. It is a top view of the light receiving element of the inclination angle detector which concerns on the said 2nd Example. It is a longitudinal cross-sectional view of the conventional inclination angle detector. It is a top view of the light receiving element of the conventional inclination angle detector. It is another top view of the light receiving element of the conventional inclination angle detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bubble tube 6 Light emission part 17 Calculation part 20, 50 Mask pattern 22, 52 Reference light passage window 23, 24, 25, 26, 53, 54, 55, 56 Position detection light passage window 30, 60 Light receiving element 32 Reference light reception Part 33, 34, 35, 36 Position detection light receiving part 63, 64, 65, 66 Light receiving part

Claims (2)

Inclination angle detection comprising a bubble tube, a light emitting unit installed below the bubble tube, a light receiving element installed above the bubble tube, and an arithmetic unit for calculating an inclination angle from the output of the light receiving element In the vessel
A mask pattern is disposed between the bubble tube and the light receiving element, and four position detection light passage windows are arranged in a cross-shaped radial pattern in the mask pattern, and a radiation direction of each position detection light passage window. Place a reference beam passage window near the outer edge,
The light receiving element has four two-split light detectors, and two light receiving portions of the two split light detectors are arranged at positions corresponding to the position detection light passage window and the reference light passage window, respectively. A featured tilt angle detector. Inclination angle detection comprising a bubble tube, a light emitting unit installed below the bubble tube, a light receiving element installed above the bubble tube, and an arithmetic unit for calculating an inclination angle from the output of the light receiving element In the vessel
A liquid crystal mask pattern is disposed between the bubble tube and the light receiving element, and in response to a command from the arithmetic unit, four position detection light passing windows disposed in a cross-shaped radial pattern on the mask pattern, A reference light passage window arranged in the vicinity of the radially outer end of the position detection light passage window is alternately formed in time,
The light receiving element has four light receiving portions, and each light receiving portion is arranged at a position corresponding to the position detection light passage window and the reference light passage window.

Images