JPH10153613A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy and response property by detecting the change in the crossed area of a row of slits of a disk that rotates in one piece with a rotator as the change in the quantity of transmission light through a row of slits. SOLUTION: Two disks are fixed facing each other at the outer periphery of a rotary shaft. One disk is a still disk and a row of slits 51 are formed. The other disk is an elastic disk and a row of slits 61 are formed. A row of slits 51 are constituted of a rectangular slit and a row of slits 61 are constituted of a triangular slit. Also, the width of a range 81 where light is transmitted is an integer multiple of the pitch of the rows of slits 51 and 61. While no acceleration is applied, a trapezoid part A where a rectangular and a triangle overlap becomes a light transmission part. When a positive acceleration is applied and slits 51a and 61a move relatively, the overlapped part changes, the light transmission part increases, and the quantity of received light increases. When a negative acceleration is applied, the quantity of transmission light decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device for detecting angular acceleration of a rotating body such as a motor shaft over an infinite rotation angle range in a non-contact state.

[0002]

2. Description of the Related Art A conventional angular acceleration sensor is disclosed in Japanese Patent Application Laid-Open No. Hei 6-337212. FIG. 13 shows a sectional view of a conventional angular acceleration sensor. This has a structure in which two optical discs are combined. The first disk is formed with a row of slits concentric with each other in the circumferential direction. On the other second disk, a second row of slits is formed so as to face the first disk. Also the second
The disc has an annular weight portion formed radially outside the slit row forming portion, and a radially elastically deformable spring portion is formed radially inside the weight portion and the slit row. It has a configuration. Therefore, when the rotating body rotates, the spring portion is slightly elastically deformed in the circumferential direction by the inertial force of the weight portion of the second disk in accordance with the change in the rotating speed of the rotating body. As a result, the second row of slits formed on the outer peripheral side of the spring portion also slightly moves in the circumferential direction. As a result, relative rotation occurs between the first slit row and the second slit row. Here, FIG.
As shown in, the first slit row and the second slit row are
These intersections are formed so as to change in accordance with the relative rotation. Therefore, the angular acceleration of the rotating body is detected by detecting the variation of the intersection position by the intersection position detection unit.

[0003]

In the above invention,
It is necessary to detect the position of the cross section of the transmitted light. In a conventional example, a PSD is used as an optical sensor for position detection. However, due to its structure, the response speed of the PSD cannot be increased, and the response of the PSD is a major factor that determines the response of the angular acceleration sensor. In order to enhance the response of the optical sensor for position detection, a high-speed CCD element may be used. However, the high-speed CCD element requires advanced technology for handling. Therefore, a PSD element is usually used as an optical sensor for position detection, and the upper limit of the response of the angular acceleration sensor is suppressed to about 1 kHz. It is difficult to use a conventional angular acceleration sensor for an application of an angular acceleration loop desired to be used at high speed. An object of the present invention is to provide a highly accurate
Moreover, it is an object of the present invention to provide an angular acceleration sensor with good responsiveness.

[0004]

Means for Solving the Problems A first disk fixed coaxially so as to rotate integrally with a rotating body, and integrally rotating with the rotating body in a state facing the first disk. Acceleration sensor comprising a second disk fixed in the coaxial state as described above, a first row of slits formed concentrically at a predetermined interval on the first disk, and the second slit in the second disk. A second slit row formed at a position facing the one slit row in the circumferential direction and intersecting the first slit row with a variable area; and a second slit formed on the second disk. An annular weight portion formed on at least one of the inner side and the outer side in the radial direction from the position where the slit row is formed, and the second disk having a radius larger than the position where the weight portion and the second slit row are formed. In the direction An elastically deformable elastic portion toward the circumferential direction, the first generated by the rotation of the rotating body
Detecting means for detecting a change in the intersection area of the second slit row with respect to the slit row.

[0005] The detecting means for detecting the angular acceleration includes:
A light-emitting element and a light-amount detecting unit disposed so as to sandwich the first and second slit rows from both sides, and a transmitted-light limiting slit having a transmission width that is an integral multiple of the first and second slit pitches; The light amount of a part of the transmitted light passing through the first slit row and the second slit row is detected. Further, the detecting means is installed at a plurality of locations in the circumferential direction of the disk. In addition, the first
Is a rectangular slit, and the second slit is a triangular slit. Also, the first slit is a rectangular slit, and the second slit is a trapezoidal slit. The first and second slits are rectangular slits having a phase difference between the slits. Further, in the angular acceleration sensor, a third slit row formed in parallel with the first slit row near the first slit row on the first disk, and the third slit row on the second disk. A fourth slit row formed in parallel with the second slit row near the second slit row so as to face the third slit row and having the same slit shape as the second slit and rotated by 180 °. And the first generated with the rotation of the rotating body.
And detecting means for detecting a change in the intersection area of the second slit row with respect to the third slit row and the fourth slit row with respect to the third slit row. The third slit is a rectangular slit, and the fourth slit is
The slit is a triangular slit. Further, the third slit is a rectangular slit, and the fourth slit is a trapezoidal slit. Further, the third and fourth slits are rectangular slits, and their slit pitches are shifted from each other by ４ pitch.

[0006]

FIG. 1 is a sectional view of an angular acceleration sensor according to a first embodiment of the present invention. Two disks 5, 6 are fixed to the outer periphery of the rotating shaft 4 in a state of facing each other. One disk 5 is a rigid disk, and on the outer peripheral side,
The first slit row 51 is formed concentrically in the circumferential direction. The other disk 6 is an elastic disk having a structure to be described later, and has a second row of slits 61 formed in the outer peripheral direction. The optical sensor 7 is arranged so as to sandwich the slit (51, 61) forming position of the first and second disks 5, 6 from both sides. The detecting unit includes a parallel light generating element (for example, a parallel light LED or an LED and a lens system) and a light amount detecting device (for example, a photodiode)
These are mounted so as to sandwich the first and second slit rows 51 and 61. FIG. 2 shows the shape of the rigid disk 5. A first slit row 51 is formed concentrically on the outer peripheral side of the disk 5. FIG. 4 shows a state where the slit rows 51 and 61 described later overlap each other in a state where no angular acceleration is applied.
FIG. 3 shows the shape of the elastic disk 6. The disk 6 is composed of an outer annular portion 67, an inner annular portion 63 forming a boss for attaching a rotating body, and three radially extending ribs 64, 65, 66 connecting them. ing. A second slit row 61 is formed in the outer annular portion 62. The three ribs 64, 65, 66 are spring portions that can be elastically deformed in the disk circumferential direction. As described above, in the disk 6, since the outer annular portion 62 is supported by the three spring ribs, the annular portion 62 is formed by the inertial force of the annular portion 62 generated with the rotation. It moves elastically in the circumferential direction. Thus, the outer annular portion 62 functions as a weight that elastically deforms the rib portion.

Next, the first and second slit rows 51 and 61 formed on the disks 5 and 6 will be described. The first row of slits 51 formed on the side of the rigid disk 5 is composed of rectangular slits formed at a constant pitch and extending in the radial direction and having a width of 1/2 pitch. On the other hand, the pitch of the slit row 61 formed on the side of the elastic disk 6 is the same as that of the slit row 51, but the shape thereof is a triangular slit row having one side in the radial direction. FIG. 4 shows a state where these slit rows 51 and 61 are developed in a linear direction from a circumferential direction. In this figure, a group of slits indicated by solid lines is a slit row 51 formed on the rigid disk 5 side.
The slit line 61 formed on the side of the elastic disk 6 is indicated by a dotted line. The range surrounded by the one-dot chain line 81 is the range through which the light from the parallel light generating element is transmitted by the limiting slit. The width of the limiting slit is an integral multiple of the pitch of the slit rows 51 and 61. For this reason, a slit of an integral multiple of the slits 51a and 61a is provided in the restriction slit. The slit 51a of the slit row 51 is a rectangular slit formed at a constant pitch p, and the slit 61a of the other slit row 61 is a triangular slit having a pitch p. The overlapping portion of these slits 51a and 61a forms a light passing portion.

In the state shown in FIG. 4 where no acceleration is applied, the trapezoidal portion A of the oblique line that overlaps the rectangle and the triangle becomes the light transmitting portion, and only the light of the oblique line portion of the light emitted from the parallel light generating element is the light amount detection The light is received by the element. At this time, if the upper and lower bases of the trapezoid are α and β, the transmission area is (１ ／) (P / 2) (α + β) = (１ ／) P (α + β) (1) The photodetector generates a voltage proportional to the amount of received light. FIG. 5 shows a state where the positive angular acceleration is applied and the slits 51a and 61a relatively move by x. The relative movement of the slits 51a, 61a causes the slits 51a, 61
The overlapping portion of a changes.

The upper and lower bases of the trapezoid at this time are α ′ = α (h + x) / h β ′ = β (h + x) / h, and the transmission area is (1/2) (P / 2) (( 1 + x / h) α + (1 + x / h) β) = (１ ／) P (α + β + x (α + β) / h) (2) [Equation (2)]-[Equation (1)] = (1/4) (P / h) x (
α + β), the area of this changing portion is determined by slits 51a and 61
The area becomes proportional to the relative movement amount x of a, and in the case of FIG. 5 in which a positive acceleration is applied, the area of the overlapping portion increases. As a result, the light transmitting portion increases, and the light receiving amount of the light amount detecting element increases, so that the voltage of the light amount detecting element increases. The amount of increase in the voltage is proportional to the relative movement amount x of the slits 51a and 61a. Conversely, the case where a negative acceleration is applied is shown in FIG. The transmitted light decreases due to the relative movement of the slits 51a and 61a,
The voltage of the light quantity detection element decreases. The amount of decrease in the voltage is proportional to the relative displacement x of the slits 51a and 61a. FIG. 7 shows a state where the slit rows 51 and 61 of the detection device according to the second embodiment of the present invention are developed in a linear direction from a circumferential direction. The slit 51a is a rectangular slit. The slit 61a is a trapezoidal slit.

FIG. 8 shows a state in which the slit rows 51 and 61 of the detection apparatus according to the third embodiment of the present invention are developed in a linear direction from a circumferential direction. The slit 51a and the slit 61a are both rectangular slits, and the length of the opening of the slit is そ れ ぞ れ pitch, and the overlapping portion of the slit at rest is １ ／ pitch. In this case,
The opening area of the limiting slit surrounded by the dashed line is four times the pitch of the slits 51a and 61a. When no acceleration is applied, the transmitted light amount is (light amount for 1/4 pitch) * (4 pitches). When a positive angular acceleration is applied, the area of the overlapping portion of the slit 51a and the slit 61a increases, and the amount of transmitted light increases. The detection voltage of the light quantity detection element increases, and the increase is proportional to the relative displacement of the slits 51a and 61a. That is, it is proportional to the applied acceleration. When a negative acceleration is applied, the amount of transmitted light decreases and the detection voltage also decreases. The decrease in the detection voltage is proportional to the negative applied acceleration.

FIG. 10 shows a fourth embodiment of the present invention.
In this example, two discs each have two sets of slit rows. In the first set, a first slit row 51 and a second slit row 61 are cut into two disks as described in the first embodiment of the present invention. And the transmission part A
1 are formed. A third slit row 52 is formed on the disk 5 and a fourth slit row 62 is formed on the disk 6 as a second set of slit rows. The slits of the fourth slit row have the same shape as the triangular slits provided in the first set, but are rotated by 180 degrees. And the transmission part A2 is formed. As a result, when the area of the transmission part A1 of the first set of slit rows increases due to the displacement of the disk 6, the transmission part A2 of the second set of slit rows decreases by the same area. Therefore, by configuring the sensor as shown in FIG. 11, an angular acceleration sensor having a differential configuration can be configured, the influence of noise can be reduced, and the sensitivity can be doubled. The slit cut into the disk 6 is not limited to a triangle but may be a trapezoid. Also, 1/4 as in the third embodiment.
A rectangular slit having a shifted pitch may be used. FIG. 9 shows a sectional view of an angular acceleration sensor according to a fifth embodiment of the present invention. An optical sensor 7 including a light emitting element, a limiting slit, and a light quantity detector is arranged at a position facing the two sets of rotating disks. By processing the signals from the two sets of optical sensors, mechanical errors such as eccentricity of the rotating disk can be reduced. When the rotating body rotates, the spring portion is slightly elastically deformed in the circumferential direction by the inertial force of the weight portion of the second disk in accordance with the change in the rotating speed of the rotating body. As a result, the second row of slits formed on the outer peripheral side of the spring portion also slightly moves in the circumferential direction, so that relative rotation between the first row of slits and the first row of disks is generated. I do.
Here, the first slit row and the second slit row are formed such that their transmission areas vary according to the relative movement between them. Accordingly, the angular acceleration of the rotating body is detected by detecting the amount of light from the light emitting element passing through the transmitting surface by the light amount detecting element. here,
In order to eliminate an error due to eccentricity of the disk or the like, it is preferable to install detection means for detecting angular acceleration at a plurality of positions in the circumferential direction of the disk and compensate for the error based on these outputs. When an angular acceleration is applied, the second disk is elastically deformed by the inertial force, and the first disk and the second disk relatively move in the circumferential direction. As a result, the first slit row and the second slit row become Move relative. And the first slit and the second
The transmission area of the overlapping portion of the slit changes. Since the change in the transmission area is proportional to the angular acceleration signal, the angular acceleration can be measured by measuring the change in the transmission area.

[0012]

According to the present invention, since the light amount detecting element is used as the optical sensor for detecting the angular acceleration, the responsiveness of the optical sensor which is a problem in the optical sensor for detecting the position is not restricted, and the responsiveness of the angular acceleration sensor is good. A sensor can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an angular acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the shape of a rigid disk of the sensor of the present invention shown in FIG. 1;

FIG. 3 is a plan view showing the shape of an elastic disk of the sensor shown in FIG. 1 of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between first and second slit rows formed on both disks when no angular acceleration is applied in the sensor of the present invention shown in FIG. 1;

FIG. 5 is an explanatory diagram showing a relationship between first and second slit rows formed on both disks when a positive angular acceleration is applied in the sensor of the present invention shown in FIG. 1;

FIG. 6 is an explanatory view showing a relationship between first and second slit rows formed on both disks when a negative angular acceleration is applied in the sensor of the present invention shown in FIG. 1;

FIG. 7 is an explanatory diagram showing a relationship between first and second slit rows formed on both disks when angular acceleration is not applied in the angular acceleration sensor according to the second embodiment of the present invention;

FIG. 8 is an explanatory diagram showing a relationship between first and second slit rows formed on both disks when angular acceleration is not applied in the angular acceleration sensor according to the third embodiment of the present invention.

FIG. 9 is a sectional view of an angular acceleration sensor according to a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a relationship between slit rows in a fourth embodiment of the present invention.

FIG. 11 is an explanatory view of a fourth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a relationship between first and second slit rows formed on both disks in a conventional angular acceleration sensor.

FIG. 13 is a sectional view showing a conventional angular acceleration sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Detecting device 4 Rotation axis 5 Rigid disk 51 First slit row 52 Third slit row 51a First slit 52a Third slit 6 Elastic disk 61 Second slit row 61a Second slit 62 Fourth slit Row 62a Fourth slit 64, 65, 66 Rib 7 Optical sensor 71, 73 Parallel light generating element 72, 74 Light quantity detecting element 8, 81, 82 Transmitted light limiting slit 9 Differential amplifier

Claims (10)

[Claims] 1. A first disk fixed coaxially so as to rotate integrally with a rotating body, and a coaxial state rotating integrally with the rotating body in a state facing the first disk. An angular acceleration sensor comprising a second disk fixed to the first disk, a first disk formed concentrically at a predetermined interval on the first disk.
And a second row formed on the second disk at a position facing the first slit row in the circumferential direction and intersecting the first slit row with a variable area.
And an annular weight portion formed on at least one of the inner side and the outer side in the radial direction from the position where the second slit row is formed on the second disk; An elastic portion formed radially inward of the weight portion and the position where the second slit row is formed and elastically deformable in the circumferential direction; and the first portion generated as the rotating body rotates. Detecting means for detecting a change in the area of intersection of said second slit row with said slit row. 2. The detecting means for detecting angular acceleration comprises: a light emitting element and a light quantity detecting means arranged so as to sandwich the first and second slit rows from both sides; and the first and second slit pitches. 2. A transmission light restricting slit having a transmission width that is an integral multiple of the first slit row and a part of transmitted light passing through the first slit row and the second slit row is detected. Angular acceleration sensor. 3. The disk drive according to claim 1, wherein said detecting means is provided at a plurality of positions in a circumferential direction of the disk.
The angular acceleration sensor according to any one of the preceding claims. 4. The angular acceleration sensor according to claim 1, wherein said first slit is a rectangular slit, and said second slit is a triangular slit. 5. The method according to claim 1, wherein the first slit is a rectangular slit, and the second slit is a trapezoidal slit.
4. The angular acceleration sensor according to any one of claims 1 to 3. 6. The angular acceleration sensor according to claim 1, wherein the first and second slits are rectangular slits having a phase difference between the slits. 7. The angular acceleration sensor according to claim 1, wherein:
A third slit row formed in parallel with the first slit row near the first slit row on the disk; and a third slit near the second slit row on the second disk. The second slit row is formed in parallel with the second slit row so as to face the row, and has the same slit shape as the second slit and has an orientation of 18
A fourth row of slits consisting of slits rotated by 0 °,
A detection means for detecting a change in the intersection area of the second slit row with respect to the first slit row and the fourth slit row with respect to the third slit row, which is generated with the rotation of a rotating body. 2. The angular acceleration sensor according to 1. 8. The slit according to claim 7, wherein the third slit is a rectangular slit, and the fourth slit is a triangular slit.
The angular acceleration sensor according to any one of the preceding claims. 9. The angular acceleration sensor according to claim 7, wherein said third slit is a rectangular slit, and said fourth slit is a trapezoidal slit. 10. The angular acceleration sensor according to claim 7, wherein said third and fourth slits are rectangular slits and their slit pitches are shifted from each other by ４ pitch.