JPH0715376B2 - Rotation angle detector - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a rotation angle detection device used as a steering angle sensor or the like of a vehicle.

[Technical Background of the Invention and Problems Thereof] The rotation angle detecting device is generally called a rotary encoder and is a device for measuring a rotation angle as a digital amount.

3 to 4 show a conventional example of such a rotation angle detecting device (Japanese Patent Application No. 59-45860). Reference numeral 1 in these figures
Is a circular rotary slit plate, and a plurality of slits 3 are drawn near the periphery of the rotary slit plate so as to draw a circle around the rotary shaft 2.
Are arrayed at a constant pitch l ₁ . (Incidentally, the slits 3 will be referred to as a slit row 3 hereinafter).
A U-shaped photo coupler 4 is fixedly installed so as to sandwich the slit row 3 of the slit plate 1 from both sides.

The photocoupler 4 includes a light receiving portion (light source) 5 and a light receiving portion 6 which are arranged to face each other with a gap interposed therebetween. A transparent resin-molded light emitting diode (LED) is used as the light receiving portion, and the slit row 3 is illuminated from one surface side of the slit plate 1 by the light from this, and the slit row 3 is lit on the surface of the light receiving portion 6 on the opposite side. To produce a light-dark pattern m.

The light receiving section 6 includes a light receiving element array (photodiode array)
(Hereinafter, the light receiving portion and the light receiving element array refer to the same object). The light receiving element array 6 is formed of six light receiving elements 6a to 6f in this conventional example, and these are arranged linearly in the arrangement direction of the slits 3. The total length of the light-receiving element 6, in other words, the array length l ₃ is the pitch l _{1 of the} slits 3.
And the length is almost the same. In FIG. 4, reference numeral 7 is one light receiving element provided on the same side as the light receiving element array 6, and this light receiving element 7 is for detecting the number of passing through the slit 3 when the slit plate 1 is rotated. is there.

Each of the light-receiving elements 6a to 6f in the light-receiving element array 6 operates independently with respect to the light-dark pattern m, and a "1" signal is output from the light-receiving element that is struck by the light through the slit 3.
The output of the light receiving element shaded by the slit plate 1 is "0".

FIG. 5 shows a signal processing system for the binary signals "1" and "0" output from the light receiving elements 6a to 6f. Fig. 5 A ₀ is a terminal for inputting the output signal of the light receiving element 6a, A ₁ is a terminal for inputting the output signal of the light receiving element 6b, and so on. Similarly, A ₂ , A ₃ , A ₄ , and A ₅ are light receiving elements 6c, respectively. , 6d, 6e, 6f are input terminals. A ₆ is a terminal for inputting the output signal of the light receiving element 7. I _{0 to} I ₄ are inverters, G _{1 to} G ₅ are NOR gates, and B _{1 to} B ₅ are output terminals of the NOR gates G _{1 to} G ₅ .

The binary detection signal detected by the light receiving element array 6 when the slit plate 1 is rotated in the direction of the arrow R in FIG. 4 is the output signal between the adjacent light receiving elements and the inverters I _{0 to} I ₄ and the NOR gate. Logical processing is performed by G _{1 to} G _{5 as} follows, and a pulse signal for measuring the rotation angle is output to each output terminal B _{1 to} B ₅ .

That is, the output of the NOR gate Gi (i = 1 to 5) becomes "1" when the input of the input terminal _A1-1 is "1" and the input of Ai is "0". That is, when the bright-dark pattern m formed by the slit array 3 moves on the light-receiving element array 6,
For example, as shown in FIG. 4, when the light receiving element 6a is "bright" and the light receiving element 6b adjacent in the rotation direction is "dark", the input terminal A ₀
At the input of the (i = 1 in A _1-1) is "1", input terminals A
The input of ₁ (Ai) becomes “0” and the output of NOR gate G ₁ (Gi) becomes “1”.

In this way, which position on the light-receiving element array 6 the light / dark boundary position h ′ in the light / dark pattern m is moved to depends on which of the output terminals B _{1 to} B ₅ outputs the “1” signal. In other words, it is detected at which position on the light-receiving element array 6 the edge h of the slit 3 has moved, the number of passing slits 3 is detected by the light-receiving element 7, and the rotary shaft 2 is detected based on both detection information. The rotation angle of is measured.

By the way, as in the above-described conventional rotation angle detecting device, the pitch l ₁ of the slits 3 having the array length l ₃ of the light receiving element array 6 is set to be substantially equal to the light / dark boundary corresponding to the edge h of the slit 3 on the light receiving element array 6. In order to project the position h ′ and detect the rotational position of the bright / dark boundary position h ′, the light projected from the light emitting unit 5 onto the slit plate 1 needs to be parallel light.

However, in the conventional rotation angle detecting device, since the light emitting diode of the transparent resin mold having the lens function is used as the light emitting unit 5, the light emitting unit 5 is close to a point light source, and the projection from this point light source is performed. The light spreads through the slit 3 and reaches the light receiving element array 6 as shown in FIG. Therefore, the edge h of the slit 3 is not detected by the light-receiving element array 6 at a position where one pitch of the slit 3 faces directly in front of the light-receiving element array 6 (the facing position in FIG. 6), and the edge h of FIG. It is detected by the light-receiving element array 6 after being rotationally moved to the middle i or j position, and is detected between h and i or j-
There is a problem that a so-called dead zone region is generated between h and the detection accuracy of the rotation angle is reduced.

As one means for solving such a problem, the space between the light emitting part 5 and the slit plate 1 is made sufficiently large so that the projection light from the light emitting part 5 is parallel in the vicinity of the position where the slit plate 1 is arranged. It is possible to consider it as light. But,
If such means is taken, there is a problem in that the light emitting section 5 requires a considerably strong light emitting source and the size of the device becomes large, and it cannot be said to be a good solution means. As another solution, as described above, the light emitting unit 5
It is conceivable to convert the light from the light emitting section 5 into parallel light by using a collimator such as a lens or an optical fiber instead of increasing the distance between the slit plate 1 and the slit plate 1. However, a collimator that uses this means is expensive. This leads to an increase in the cost of the device, and this means cannot be said to be a means for solving an appropriate problem. Therefore, there has been a demand for a rotation angle detection device capable of accurately detecting a rotation angle even when a relatively inexpensive transparent resin-molded light emitting diode is used for a light emitting portion.

[Object of the Invention] The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to detect a rotation angle with high accuracy even if a point light source-like light source is used. An object is to provide a rotation angle detection device that can be used.

[Summary of the Invention] In order to achieve the above object, a first invention is a rotary slit plate in which slit rows are provided at a predetermined disposition pitch on a circumference around a rotary shaft, and the rotary slit plate. A light source arranged to illuminate a portion of the slit row from one surface side to generate a bright and dark pattern by the slit row on the opposite side, and a light source in which an irradiation region of emitted light expands in proportion to a distance, and to receive the bright and dark pattern And a light-receiving element array in which a required number of light-receiving elements that output photoelectric conversion signals for detecting rotation angles are arranged in the same direction as the slit row, and the array length l ₂ of the light-receiving element array is The arrangement pitch is l ₁ , and the interval length between the light source and one surface of the rotary slit plate is
When d _{1 is} the distance between the light source and the light receiving element array, and d ₂ is,
It is characterized in that l ₂ = l ₁ · d ₂ / d ₁ .

A second invention is a rotary slit plate in which slit rows are provided at a predetermined arrangement pitch on a circumference around a rotation axis, and a portion of the slit row is illuminated from one surface side of the rotary slit plate. A light source that is installed on the opposite side so as to generate a light-dark pattern by the slit row, and the irradiation area of the emitted light expands in proportion to the distance, and the light-dark pattern is received and photoelectric conversion signals for rotation angle detection are received. A light receiving element array in which a required number of light receiving elements to be output are arranged in the same direction as the slit array; and the array length l ₂ of the light receiving element array has a slit arrangement pitch l ₁ , a light source and a rotary slit. The distance between the two sides of the plate
d ₁ , the thickness of the rotary slit plate is t, the interval length between the light source and the light receiving element array is d ₂ , and when one pitch of the slit is opposed to the light receiving element array, the darkness of the bright and dark pattern formed by the slit is When the array length of the light receiving element array corresponding to the pattern portion is l ₂ ′ and the array length of the light receiving element array corresponding to the bright pattern portion in the light-dark pattern is l ₂ ″, l ₂ =
characterized in that l ₂ '+ l ₂ "= a _{1 · d 2 / 2d 1 +} l 1 · d 2/2 (d 1 + t).

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. The first
In the drawing and FIG. 2 described later, the same or equivalent members or parts as those in FIGS. 3 to 6 are designated by the same reference numerals as those described above, and a duplicate description will be omitted.

First, the configuration will be described. In this embodiment, as the light emitting section 5, a transparent resin mold light emitting diode, that is, a light emitting diode in which an irradiation region of emitted light is expanded in proportion to a distance is used as in the conventional example. The array length l ₂ of the light receiving element array 6 is defined as follows in consideration of the respective arrangement intervals between the light emitting section 5 and the slit plates 1 and between the light receiving element arrays 6.

That is, the arrangement pitch of the slits 3 in the slit plate 1 is l ₁ , the interval length between the light emitting portion 5 and one surface of the slit plate (a surface facing the light emitting portion 5) is d ₁ , the light emitting portion 5 and the receiving element array. When the distance between the photosensors 6 and 6 is d ₂ , the array length l ₂ of the photodetector array 6 is
It is specified that l ₂ = l ₁ · d ₂ / d ₁ . That is, the array length l ₂ of the light receiving element array is defined to be substantially equal to the length of the shadow of one pitch of the slit 3 formed by the projection light from the light emitting section 5 at the position where the light receiving element array 6 is arranged. There is.

As the signal processing system for the binary signals "1" and "0" output from each of the light receiving elements 6a to 6f, the same signal processing circuit as that shown in FIG. 5 is used.

Next, the operation will be described. Since a light emitting diode close to a point light source is used for the light emitting section 5, the projection light from this point light source spreads through the slit 3 and reaches the light receiving element array 6 as shown in FIG. At this time, the bright and dark pattern m created by the slit 3 at the position where the light receiving element array 6 is arranged.
And the light receiving element array 6 is reached. The sequence length l _{2 of} the above-mentioned is almost the same, and the dead zone region as shown in FIG. 6 does not occur.

As the slit plate 1 rotates, the light-dark boundary position h'corresponding to the edge h of the slit 3 moves on the light receiving element array 6 from the light receiving element 6a to the next light receiving elements 6b, 6c. From the output terminals B ₁ , B ₂ , ... Of the signal processing circuit, pulse signals, which are rotation angle information of the rotary shaft 2, are sequentially output.
Thus, the rotation angle of the rotary shaft 2 is accurately measured by this rotation angle information and the detection information of the number of passing slits detected by the light receiving element 7.

Next, FIG. 2 shows another embodiment of the present invention. In this embodiment, the array length l ₂ of the light receiving element array 6 is defined in consideration of the thickness t of the slit plate 1.

As described above, the rotation angle detecting device according to the present invention rotates by detecting the light-dark boundary position h'formed by the edge of the slit 3 (reference numeral h in FIG. 1) by the light receiving element array 6. One piece of information for detecting the rotation angle of the shaft 2 is obtained.

When the slit plate 1 has a thickness t that cannot be ignored, the light-dark boundary position h ′ is affected by the thickness t of the slit plate 1 as follows.

That is, when the center line connecting the center of the light emitting section 5 and the center of the light receiving element array 6 is designated by reference numeral 8, and when the edge of the slit 3 is located on the right side of the center line 8 in FIG. The light-dark boundary position h ′ is one surface of the slit plate 1 (a surface facing the light emitting unit 5).
Is formed by the edge h ₁ side, while the edges of the slit 3, when moving to the second left hand side of the drawing position of the center line 8, the bright-dark limit position, the edge of the other side of the slit plate 1 h ₂ Is formed by.

Since the distance from the light emitting portion 5 to each surface of the slit plate 1 differs from the other surface by the thickness t of the slit plate 1, the center line 8 rotates on the right side in FIG. 2 and the left side. The amount of movement of the light-dark boundary position h'when the axis 2 rotates by the same angle is different. Therefore, even if the total array length l ₂ of the light receiving element array 6 is defined in consideration of the distance d ₁ between the light emitting part 5 and the slit plate 1 as in the embodiment of FIG. 8 has an array length l ₂ ′ on the right side in FIG. ₂ and an array length l ₂ ″ on the left side in FIG. ₂ that have the same length, the light receiving element array 6 accurately determines the rotational movement position of the edge of the slit 3. Can not be detected.

Therefore, in this embodiment, the array length l ₂ of the light receiving element array 6 is defined as follows in consideration of the thickness t of the slit plate 1.

That is, the arrangement pitch of the slits 3 is l ₁ , the interval length between the light emitting part 5 and one surface of the slit plate 1 is d ₁ , the thickness of the slit plate 1 is t ₁ , and the interval between the light emitting part 5 and the light receiving element array 6 is Length is d ₂ ,
When one pitch of the slit 3 (the length from the edge h ₁ to the next edge h 2 in FIG. ₂ ) is opposed to the light receiving element array 6 (opposing state in FIG. 2), the slit 3 causes When the array length of the light receiving element array 6 corresponding to the dark pattern portion of the formed light and dark pattern m is l ₂ ′ and the array length of the light receiving element array 6 corresponding to the bright pattern portion is l ₂ ″, the light receiving element The total array length l ₂ of column 6 is l ₂ = l ₂ ′ + l ₂ ″ = l ₁ · d ₂ / 2d ₁ + l ₁ · d ₂ /
It is specified to be 2 (d ₁ + t). And the second
As shown in the figure, when three light-receiving elements are arranged on each side of the center line 8, the length of one light-receiving element on the array length l ₂ ′ side is 1 ₂ ′ / 3. The length of one light receiving element on the array length l ″ side is l ₂ ″ / 3.

In operation, when the edge of the slit 3 detected by the light receiving element array 6 is on the right side of the center line 8 in FIG. 2, the boundary position h ′ of the bright-dark pattern m formed on the light receiving element array 6 is , formed by the edge h ₁ of one side of the slit plate 1, also when in the second drawing left of the center line 8, the boundary position h 'is formed by the edge h ₂ of the other end side of the slit plate 1 The formation position thereof is influenced by the thickness t of the slit plate 1, but the lengths of l ₂ ′ and l ₂ ″ corresponding to the respective array lengths of the light-receiving element array 6 corresponding to the right and left sides of the center line 8 are set. Is defined in consideration of the thickness t of the slit plate 1, so that a dead zone does not occur as in the case of the first embodiment, and the edge of the slit 3 detected by the light receiving element array 6 is , The right side of the center line 8 in FIG. 2 or the left side of FIG. Even, the number of passes of the light receiving element when rotated moves by the same angle amount becomes equal number, the rotation angle is accurately detected.

[Effects of the Invention] As described above, in the first invention, the array length l ₂ of the light receiving element array is the shadow of one pitch of the slit formed at the arrangement position of the light receiving element array by the irradiation light from the light source. The length of one pitch of the light-dark pattern formed at the position where the light receiving element array is arranged by the slit and the array length l ₂ of the light receiving element array are substantially equal to each other. A dead zone region does not occur on the light receiving element array.

Further, in the second invention, the arrangement length l ₂ of the light receiving element array is taken into consideration in consideration of the thickness t of the slit plate, the arrangement pitch of the slits is l ₁ , the light emitting portion 5 and the one surface of the slit plate 1 are arranged. When the interval length is d ₁ , the thickness of the slit plate 1 is ₁ , the interval length between the light source and the light-receiving element array is d ₂ , and one pitch of the slit is opposed to the light-receiving element array, it is formed by the slit. When the array length of the light-receiving element array corresponding to the dark pattern portion of the light-dark pattern m is l ₂ ′ and the array length of the light-receiving element array corresponding to the light pattern portion is l ₂ ″, the total array length of the light-receiving element array l ₂ is
_{l 2 = l 2 '+ l} 2 "= l 1 · d 2 / 2d 1 + l 1 · d 2/2 (d 1 + t)
Therefore, even if the thickness of the slit is such that it affects the boundary position of the light and dark patterns, it is possible to use one of the light and dark patterns formed by the slits at the arrangement position of the light receiving element rows. The length corresponding to the pitch and the array length l _{2 of} the light receiving element array substantially match, and a dead zone region does not occur on the light receiving element array.

Therefore, according to the first and second aspects of the invention, the irradiation area expands in proportion to the distance, and even if a light source that can be regarded as a point light source is used, a dead zone occurs in detecting the slit rotation position on the light receiving element array. Therefore, the rotation angle of the rotating shaft can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a front view schematically showing a main part of an embodiment of a rotation angle detecting device according to the present invention, and FIG. 2 is a front view schematically showing a main part of another embodiment of the present invention. FIG. 3 is a partially sectional front view of a conventional rotation angle detecting device, and FIG. 4 is IV-IV of FIG.
FIG. 5 is a block diagram of the detection signal system of the conventional apparatus, and FIG. 6 is a partial front view for explaining the problems of the conventional apparatus. 1 ... Rotating slit plate, 2 ... Rotation axis, 3 ... Slit, 5 ... Light emitting part (light source), 6 ... Light receiving element array, 6a to 6f
……Light receiving element.

Claims (2)

[Claims] 1. A rotary slit plate in which slit rows are provided at a predetermined pitch on a circumference around a rotary shaft, and a portion of the slit row is illuminated from one side of the rotary slit plate to be opposite. A light source which is arranged on the side so as to generate a light-dark pattern by the slit array, and the irradiation area of the emitted light expands in proportion to the distance; and the light-dark pattern is received to output a photoelectric conversion signal for detecting a rotation angle, respectively. And a light receiving element array in which a required number of light receiving elements are arranged in the same direction as the slit array, and the array length l ₂ of the light receiving element array has a slit arrangement pitch l ₁ , a light source and a rotary slit plate. The distance between the surfaces
When d _{1 is} the distance between the light source and the light receiving element array, and d ₂ is,
A rotation angle detection device, wherein l ₂ = l ₁ · d ₂ / d ₁ . 2. A rotary slit plate in which slit rows are provided at a predetermined pitch on a circumference around a rotation axis, and a portion of the slit row is illuminated from one surface side of the rotary slit plate to oppose it. A light source that is installed on the side so as to generate a bright-dark pattern by the slit array, and the irradiation area of the emitted light expands in proportion to the distance, and the bright-dark pattern is received, and photoelectric conversion signals for rotation angle detection are output. And a light receiving element array in which a required number of light receiving elements are arranged in the same direction as the slit array, and the array length l ₂ of the light receiving element array has a slit arrangement pitch l ₁ , a light source and a rotary slit plate. The distance between the surfaces
d ₁ , the thickness of the rotary slit plate is t, the interval length between the light source and the light receiving element array is d ₂ , and when one pitch of the slit is opposed to the light receiving element array, the darkness of the bright and dark pattern formed by the slit is When the array length of the light receiving element array corresponding to the pattern portion is l ₂ ′ and the array length of the light receiving element array corresponding to the bright pattern portion in the light-dark pattern is l ₂ ″, l ₂ =
l ₂ '+ l ₂ "= rotational angle detecting device which is a _{l 1 · d 2 / 2d 1} + l 1 · d 2/2 (d 1 + t).