JP3160372B2 - Rotation angle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a light projecting element and a semiconductor position detecting element opposed to each other with a rotating plate attached to a rotating shaft interposed therebetween, and a rotating plate based on a light receiving signal from the semiconductor position detecting element. The present invention relates to a rotation angle detection device that detects a rotation angle of a camera.

[0002]

2. Description of the Related Art An example of this kind of rotation angle detecting device is shown in FIG.
This will be described with reference to FIG. This device is configured so that the rotation angle of the rotating plate can be detected with high accuracy even when "play" occurs between the rotating shaft and the rotating plate.

That is, in FIG. 12, a rotating plate 2 is attached to a rotating shaft 1 so as to rotate integrally with the rotating shaft 1. The light transmitting portion 3 is formed, and a reference light transmitting portion 4 having an annular shape with a predetermined radius is formed near the outer periphery thereof.

A light-emitting diode (hereinafter, referred to as an LED) 5 and a semiconductor position detecting element (Position) for detection are provided on a fixed portion (not shown) with the light-transmitting portion 3 for detection of the rotating plate 2 interposed therebetween.
A Sensitive Detector (hereinafter abbreviated as PSD) 6 is arranged so as to oppose, and the LED 7 and the reference PSD 8 are arranged so as to oppose each other with the reference light transmitting portion 4 interposed therebetween. The detection PSD 6 and the reference PSD 8
Are arranged to detect the position of incident light that changes in the radial direction of the rotating plate 2.

[0005] In FIG. 13 showing the outline of the electrical configuration,
The outputs of the detection PSD 6 and the reference PSD 8 are supplied to a subtractor 11 via amplifiers 9 and 10, respectively. Amplifier 9,
Reference numeral 10 denotes current signals S1, S provided from PSDs 6, 8, respectively.
2 is amplified, converted into voltage signals V1 and V2, and output. The subtracter 11 calculates the difference V between the voltage signals V1 and V2.
12 (= V1−V2) is calculated and output.

According to the above configuration, when the rotating plate 2 is rotated, the detecting light transmitting portion 3 and the reference light transmitting portion 4 are correspondingly rotated.
Rotates. In this case, the reference light transmitting part 4 is
Is formed in an annular shape around the center of rotation O, and in principle, the position of the light incident on the reference PSD 8 from the LED 7 via the reference translucent unit 4 even when the LED 7 is rotating. Does not fluctuate.

On the other hand, since the detecting light-transmitting portion 3 that rotates and rotates with the rotation of the rotary plate 2 is formed in a spiral shape, the radial distance r changes linearly with the rotation angle θ. . That is, the position of the light that enters the detection PSD 6 from the LED 5 via the detection light transmitting unit 3 is determined by the rotation angle θ of the rotating plate 2.
Changes continuously in accordance with. At this time, the light reception signal S1 of the detection PSD 6 is obtained as S1 = A × θ + B (1) (where A and B in the equation (1) are constants), and the light reception signal of the reference PSD 8 S2 is obtained as S2 = C (constant) (2).

The amplifiers 9 and 10 amplify the given light receiving signals S1 and S2, respectively, convert the signals to voltage signals V1 and V2, and provide the resulting signals to a subtractor 11. Subtractor 1
1 calculates the difference V1-V2 between the applied voltage signals V1 and V2 and outputs the result as an output signal V12. Accordingly, the output signal V12 is set as a value corresponding to the value S12 (= S1-S2) obtained by subtracting S2 from the light receiving signal S1.
Will be output. That is, equations (1) and (2)
From S12, S12 = S1−S2 = A × θ + (B−C) = A × θ + D (3) Therefore, S12, that is, the output V12 of the subtractor 11 is a value proportional to the rotation angle θ. (But D
(= BC) is a constant.) Therefore, as described above, the rotating plate 2 is controlled based on the value of the output voltage V12 of the subtractor 11.
The rotation angle θ of the rotating plate 2 can be detected in a wide range from the reference position (0 °) to nearly 360 °, as shown in FIG.

Then, the rotating plate 2 is mounted at a position eccentric with respect to the rotating shaft 1, or "play" occurs between the rotating shaft 1 and the bearing portion, and the rotating position of the rotating plate 1 is reduced. When it is unstable, the light receiving signals S1 and S2 from each of the PSDs 6 and 8 both fluctuate unstablely,
Equations (1) and (2) are no longer satisfied.

However, even in the case described above, the relative positions of the detecting light transmitting portion 3 and the reference light transmitting portion 4 formed on the rotating plate 2 do not change.
The values of the light receiving signals S1 and S2 of No. 8 are output as signals which are equally added or subtracted by the amount of the eccentricity of the rotating plate 2.

Therefore, assuming that the deviation component of the light receiving signal due to the eccentricity of the rotating plate 2 at the rotation angle θ is ΔS, the PSD
The light receiving signals S1 and S2 of 6, 8 can be expressed by the following equations (1) and (2) as follows: S1 = A × θ + B + ΔS (4) S2 = C + ΔS (5) Output V1
When the signal S12 corresponding to 2 is obtained according to the equation (3),
Since the shift component ΔS due to the eccentricity of the rotating plate 2 cancels out, the result is the same as the result of the equation (3).

That is, even if there is a shift component ΔS of the received light signal caused by the eccentricity of the rotating plate 2, the relative positional relationship between the detecting light transmitting portion 3 and the reference light transmitting portion 4 is unchanged. The shift component ΔS is canceled by the subtraction in the subtractor 11, and the same detection result as in a normal case where no eccentricity occurs can be obtained. As a result,
Even when the position of the light transmitted through the detecting light transmitting unit 3 becomes unstable, such as when the rotating plate 2 is eccentric or the “rotation” of the rotating shaft 1 occurs, the rotation angle θ of the rotating plate 2 Can be accurately detected over a wide range.

[0013]

However, the conventional configuration as described above has the following disadvantages.
That is, as shown in FIG. 14, in a region (A) near the rotation angle of 0 ° where both ends 3a and 3b of the detecting light-transmitting portion 3 are located, the value of the output V12 sharply changes. Since the range of the changing level is the same as the changing level range of the other region (a), the rotation angle θ of the rotating plate 2 cannot be reliably detected only by the level value of the output V12. .

In order to solve such a problem, for example, a configuration may be considered in which another detection element is provided at that position for identification. However, this configuration complicates the configuration as a whole and increases its cost. This causes a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a simple and inexpensive configuration capable of accurately detecting the rotation angle θ of a rotating shaft over the entire 360 ° region. An angle detecting device is provided.

[0016]

According to the present invention, there is provided a rotation angle detecting device comprising: a rotating plate attached to a rotating shaft; and a reference light transmitting portion having a predetermined width and formed in a circular shape with a predetermined radius. A light-transmitting portion for detection having a constant width formed along the circumferential direction of the rotating plate and having a continuously changing distance from the center of rotation of the rotating plate; a light-transmitting portion for reference and a light-transmitting portion for detection; A light-emitting element that projects light toward the light unit, and receives light transmitted through the reference light-transmitting unit, which is disposed to face the light-emitting element with the rotating plate interposed therebetween, and receives the light in the radial direction of the rotating plate. A reference semiconductor position detecting element for detecting a light receiving position, and a light receiving element which is arranged to face the light emitting element with the rotating plate interposed therebetween and transmits through the detecting light transmitting portion, and receives the light in the radial direction of the rotating plate. A semiconductor position detecting element for detecting a light receiving position and a reference semiconductor position Calculating means for calculating a rotation angle of the rotating plate based on a light receiving signal from the detecting element and the semiconductor position detecting element for detection, wherein the rotating plate becomes discontinuous at both ends of the light transmitting portion for detection. It is characterized in that one of the detection light transmission portion and the reference light transmission portion is provided with an identification light transmission portion having a width different from that of the other portion corresponding to the angular position.

[0017]

According to the rotation angle detecting device of the present invention, the rotation angle of the rotating plate can be accurately detected over the entire circumference as follows. That is, since the reference light-transmitting portion of the rotary plate is formed in an annular shape with a predetermined radius, the light receiving position of the light incident on the reference semiconductor position detecting element from the light emitting element is the same regardless of the rotation of the rotary plate. The position in the direction is a fixed position. On the other hand, since the light transmitting portion for detection of the rotating plate has a shape in which the distance from the center of rotation continuously changes, discontinuous points (for example, near 0 °) at both ends of the light emitting portion for detection are removed. In the part, the light receiving position of the light incident on the detection position detecting element from the light emitting element with the rotation of the rotating plate continuously changes according to the rotation angle.

Therefore, when the difference between the position detected by the light receiving signal from the reference semiconductor position detecting element and the position detected by the light receiving signal from the detecting semiconductor position detecting element is calculated by the calculating means, the rotation of the rotating plate is calculated. A value corresponding to the corner can be obtained. In this case, even if there is “backlash” between the rotating shaft and the bearing, or the mounting state between the rotating plate and the rotating shaft is eccentric, the reference transparency according to the rotating angle of the rotating plate. Since there is no error in the relative distance between the light part and the light transmitting part for detection, the rotation angle of the rotating plate can be detected with high accuracy.

At the discontinuous point where both ends of the detecting light projecting portion are located, the light receiving position of the light from the light projecting element incident on the detecting semiconductor position detecting element rapidly changes. At this time, since the light from the light projecting element incident on the semiconductor position detecting element generally has a slight spread, the level of the detected signal is at the end of the discontinuous point (for example, when the rotation angle θ is greater than 360 °). ) From the level at the position where the rotation angle θ is 0 °) to the level at the start of the discontinuous point (the position where the rotation angle θ is 0 °).

However, at this discontinuous point,
Since the discriminating light projecting portion having a width different from that of the other portion is formed in either the reference transmissive portion or the detecting translucent portion, the level of all incident light at that time changes. . Therefore, by detecting the amount of light incident through the discriminating light-transmitting portion, it is possible to discriminate that the rotation position of the rotating plate is at a discontinuous point (the rotation angle is around 0 °), ,
Even if the signal output from the arithmetic means is at the same level as in the case described above, it can be distinguished, so that the rotation angle can be accurately detected over the entire circumference of the rotating plate.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

That is, in FIG. 2 showing a longitudinal side surface, a rotating shaft 21 is pivotally supported by a case 22 and rotates with the rotation of a detection target (not shown). A disk-shaped rotating plate 23 is fixed to the rotating shaft 21. The rotating plate 23 is mainly made of a transparent member such as glass or plastic, and a metal film such as chromium is deposited on the surface thereof to form an opaque layer 24.

The opaque layer 24 is partially removed by an etching process, and as shown in FIG. 1, a light transmitting portion 25 for detection and a light transmitting portion 26 for reference are formed.
The reference light transmitting portion 26 is formed in a ring shape at a position at a predetermined radius from the rotation center O of the rotating plate 23. Further, the detecting light transmitting portion 25 is located inside the reference light transmitting portion 26 and the distance r with respect to the rotation center of the rotating plate 23 is the reference position (θ = 0 °).
Is formed so as to continuously change in proportion to the rotation angle θ from. This relationship can be expressed by an equation as follows: r = a × θ + b (6) where a and b are constants determined by the shape of the light transmitting unit 25 for detection.

In the portion corresponding to the reference position (θ = 0 °), since the detecting light-transmitting portion 25 has the relationship of the above-mentioned formula (6), the portion between the light-transmitting portion 25 and the both end portions 25a and 25b is located. In other words, the rotation angle θ is discontinuous at a portion from 360 ° to 0 °. In the reference light-transmitting portion 26, an identification light-transmitting portion 16a having a larger width dimension than other portions is formed at a position corresponding to the discontinuous portion of the detection light-transmitting portion 25.

A light emitting diode (hereinafter referred to as LE)
D) 27, 28 are disposed on the upper surface inside the case 22, and include a semiconductor position detecting element for detection (hereinafter, referred to as PSD for detection) 29 and a semiconductor position detecting element for reference (hereinafter, referred to as reference PSD). Reference numeral 30 is provided on the lower surface inside the case 22 so as to detect a light receiving position in the radial direction of the rotating plate 23. Then, the LED 27 and the detection PSD 29
The LED 28 and the reference PSD 30 are disposed so as to face each other across the reference light-transmitting portion 26 of the rotating plate 23. .

FIG. 3 shows an electrical block configuration. In the detection PSD 29, one output terminal is connected to one input terminal of an adder 32 via a current-voltage conversion circuit 31. The other output terminal is connected to the other input terminal of the adder 32 via the current-voltage conversion circuit 33 and to one input terminal of the subtracter 34. The current-voltage conversion circuits 31 and 33 are respectively
The detection currents I1 and I input from the detection PSD 29
2 is converted into voltage signals V1 and V2 and output. The adder 32 calculates the sum of these voltage signals V1 and V2 and outputs the result as a voltage signal VTa (= V1 + V2).

One input terminal of the feedback circuit 35 is an adder 3
2 and the other input terminal is connected to the output terminal of the reference voltage generating circuit 36, so that the reference voltage VS is supplied. The output terminal of the feedback circuit 35 is grounded via the LED 27 so as to supply the LED 27 with the current IL1. in this case,
The feedback circuit 35 controls the current IL1 to the LED 27 so that the value of the voltage signal VTa from the adder 32 becomes equal to the reference voltage VS.

Next, in the reference PSD 30, one output terminal is connected to the adder 3 via the current-voltage conversion circuit 37.
8 is connected to one input terminal, and the other output terminal is connected to the other input terminal of the adder 38 via the current-voltage conversion circuit 39 and to the other input terminal of the subtractor 34. The current-voltage conversion circuits 37 and 39 convert the detection currents I3 and I4 input from the reference PSD 30 into voltage signals V3 and V4, respectively, and output the converted signals. An adder 38 outputs these voltage signals V3 and V4. The sum is calculated and output as a voltage signal VTb (= V3 + V4).

One input terminal of the feedback circuit 40 is an adder 3
8 and the other input terminal is connected to the output terminal of the reference voltage generation circuit 36 so that the reference voltage VS is supplied. The output terminal of the feedback circuit 40 is grounded via the LED 28 and the current detection resistor 41 so as to supply the LED 28 with the current IL2. In this case, the feedback circuit 40 includes the adder 38
Is controlled so that the value of the voltage signal VTb from the LED becomes equal to the reference voltage VS.

The subtractor 34 subtracts the value of the voltage signal V4 output from the current-voltage conversion circuit 39 from the voltage signal V2 output from the current-voltage conversion circuit 33, and outputs the result as the detection voltage V
D (= V2−V4) is output.
A common connection point between the LED 28 and the current detection resistor 41 is a rotation region identification terminal P, and the terminal voltage VJ of the current detection resistor 41 is output according to the current IL2 flowing through the LED 28 and the current detection resistor 41. ing.

Next, the operation of the present embodiment will be described with reference to FIG. When the rotating shaft 21 and the rotating plate 23 rotate with the rotation of the detection target (not shown), the light transmitting unit 25 for detection and the light transmitting unit 26 for reference rotate accordingly. In this case, since the reference light-transmitting portion 26 is formed in an annular shape around the rotation center O of the rotating plate 23, even in a state where the reference light-transmitting portion 26 is rotated, the reference light-transmitting portion 2 is in principle provided by the LED 28.
The position of the light incident on the reference PSD 30 via 6 does not change.

Further, since the detecting light-transmitting portion 25 that rotates and rotates with the rotation of the rotating plate 23 is formed in a spiral shape in which the radial distance changes according to the relationship shown in Expression (6), LE
PSD 27 for detection from D27 via translucent part 25 for detection
Is changed continuously except for a region where the rotation angle θ of the rotating plate 23 is around 0 °.

In this case, when the rotation angle θ of the rotating plate 23 is around 0 °, the position of the light incident on the PSD 29 for detection is a discontinuous point where both ends 25a and 25b of the light transmitting portion 25 for detection are located. Does not change continuously. For this reason, in the present embodiment, the configuration is such that the reference translucent portion 26 is provided with the identification translucent portion 26a, and the detection of this portion will be described later. Hereinafter, first, a region excluding a region where the rotation angle θ of the rotating plate 23 is around 0 ° will be described.

Now, according to the rotation angle θ of the rotating plate 23, the position d1 of the light incident on the light receiving surface of the detection PSD 29 from the LED 27 is obtained from the equation (6) as a value displaced in the radial direction. Assuming that B is a constant, d1 = Aθ + B (7)

An LED is provided on the light receiving surface of the reference PSD 30.
Since the position d2 of the light incident from 28 is a constant position regardless of the rotation angle θ of the rotating plate 23 as described above, if C is a constant, d2 = C (8) can be expressed.

On the other hand, the detection currents I1,
I2 is input to the adder 32 as voltage signals V1 and V2 via the current-voltage conversion circuits 31 and 33, respectively, and is input to the feedback circuit 35 as a voltage signal VTa of their sum. As a result, the feedback circuit 35 energizes the LED 27 so as to reduce the difference voltage when the value of the voltage signal VTa is higher than the reference voltage VS, and increases the difference voltage when the value is smaller than the reference voltage VS. LED27
Turn on electricity. Accordingly, the output current I corresponding to the total amount of light received from the LED 27 incident on the detection PSD 29 is obtained.
The value of the sum of (I1, I2) (I1 + I2) is controlled to be always constant.

In exactly the same way, the reference PSD 30
The detected currents I3 and I4 of the current-voltage conversion circuit 3
8 and 40 as adder 38 as voltage signals V3 and V4.
, And the sum is input to the feedback circuit 40 as a voltage signal VTb. As a result, the feedback circuit 40 controls the current supplied to the LED 28 such that the value of the voltage signal VTb becomes substantially constant corresponding to the value of the reference voltage VS. Then, the LED 28 incident on the reference PSD 30
Is controlled so that the value of the sum (I3 + I4) of the output currents I3 and I4 corresponding to the total amount of light received from the light source is always equal to (I1 + I2) and constant.

As a result, a value corresponding to the detection position d1 is obtained from the signal voltage V2 output from the current-voltage conversion circuit 33, and a value corresponding to the detection position d2 is obtained from the voltage signal V4 output from the current-voltage conversion circuit 39. Is obtained. Therefore, the voltage signal VD (= V2−V4) output from the subtractor 34 that calculates the difference between the detected positions d1 to d4
It can be obtained as a value corresponding to the distance obtained by subtracting 2.

As a result, by detecting the voltage signal VD, from the equations (7) and (8), d1−d2 = A × θ + (BC) = A × θ + D (9) Voltage signal VD output from subtractor 34
Is obtained as a value proportional to the rotation angle θ of the rotating plate 23 (however, in the equation (9), D (= BC) is a constant).

Accordingly, as described above, the rotation angle θ of the rotating plate 13 is changed based on the value of the output voltage VD of the subtractor 34 as shown in FIG.
Therefore, the rotation angle θ of the rotating plate 13 can be detected in a range other than the rotation angle θ as the reference position except around 0 °.

Incidentally, the rotating plate 23 is mounted at a position eccentric with respect to the rotating shaft 21 or the rotating shaft 2
In the case where “1” is generated between the bearing portion of the case 22 and the rotational position of the rotating plate 23 is unstable, the light receiving signals V2 and V4 from the PSDs 29 and 30 are both unstable. And the relations of the equations (7) and (8) are not satisfied.

However, even in the case described above, the relative positions of the detecting light transmitting portion 25 and the reference light transmitting portion 26 formed on the rotating plate 23 do not change, so that the PS
The values of the light receiving signals V2 and V4 of D29 and D30 are output as signals which are equally added or subtracted by the amount of the eccentricity of the rotating plate 23.

Therefore, the rotating plate 23 at the rotation angle θ is now
Let Δd be the shift component of the received light signal due to the eccentricity of
The light receiving signals V2 and V4 of D29 and D30 are given by Expression (7),
From (8), d1 = A × θ + B + Δd (10) d2 = C + Δd (11) From these, the voltage signal VD ′ corresponding to the voltage signal VD output from the subtractor 34 can be expressed by the equation (9). )
, The shift component Δd due to the eccentricity of the rotating plate 23 is canceled out, and as a result, the same value as the value shown by the equation (9) is obtained.

That is, even if there is a shift component Δd of the light receiving signal caused by the eccentricity of the rotating plate 23, the light transmitting portion 2
Since the relative positional relationship between 5 and the reference light transmitting unit 26 is invariable, the shift component Δd is canceled by the subtraction in the subtractor 34, which is the same as in the normal case where no eccentricity occurs. The detection result can be obtained.

Next, near the rotation angle θ = 0 ° where the rotating plate 23 is the reference position, the rotation angle θ is detected as follows. That is, in this area, the detection PSD2
The light receiving position of the light from the LED 27 incident on the light source 9 rapidly moves between the two end portions 25a and 25b of the light transmitting portion 25 for detection.

In this case, since the light of the light emitting diode generally slightly spreads, the light of the LED 27 in this region is different from the light incident on the PSD 29 for detection via the one end 25a of the light transmitting portion 25 for detection. The amount of light that enters the detection PSD 29 via the other end 25b gradually changes with the rotation of the rotating plate 23. Therefore, the voltage signal VD obtained from the subtractor 34 based on the signal received by the detection PSD 29 at this time changes linearly although sharply as shown in FIG.

Since such a change in the voltage signal VD is the same as the above-mentioned change region except for the rotation angle θ of the rotating plate 23 near 0 °, the rotation angle θ is obtained only from the value of the voltage signal VD.
Cannot be specified. Therefore, based on the terminal voltage VJ given from the rotation area identification terminal P, the rotating plate 23
Are identified as follows.

That is, as described above, the detection currents I3 and I4 of the reference PSD 30 are controlled by the feedback circuit 40 so that the sum (I3 + I4) is always constant. On the other hand, when the rotation angle θ of the rotating plate 23 is near 0 °, the reference translucent portion 26 a is positioned relative to the reference PSD 30. Since the width of the translucent portion for identification 26a is wider than the other portions,
The amount of light incident from the LED 28 will be increased.

Then, the value of the sum (I3 + I4) of the detection currents of the reference PSD 30 increases, so that the feedback circuit 40
Represents the amount of light incident on the reference PSD 30 as the reference voltage VS.
Is controlled so as to reduce the current IL2 to the LED 28 in order to reduce the current to a value corresponding to When the energizing current IL2 to the LED 28 decreases, the terminal voltage of the current detection resistor 41 decreases, so that the terminal voltage VJ appearing at the rotation region identification terminal P has a rotation angle θ of 0 ° as shown in FIG.
Low level in nearby area. Therefore, when the level of the terminal voltage VJ appearing at the rotation region identification terminal P is decreasing, it can be determined that the rotation angle θ of the rotating plate 23 is in a region near 0 °, and thereby the value of the voltage signal VD is reduced. The rotation angle θ of the rotating plate 23 can be detected based on the rotation angle θ.

As described above, in this embodiment, the reference light transmitting portions 26 correspond to the positions of the discontinuous points of the light transmitting portions 25 formed on the rotating plate 23, that is, both ends 25a and 25b.
And a translucent portion for identification 26a having a wider width than other portions.
, And the reference PSD 30 from the LED 28 in this portion.
Since the change in the amount of light to the light source is detected and identified by the current detection resistor 41, the voltage signal V
Even in a region where the rotation angle θ is close to 0 °, which cannot be detected only by the value of D, it can be reliably detected with a simple configuration without providing another detector or the like.

In this embodiment, the feedback circuit 35
And 40, and based on voltage signals VTa and VTb provided via adders 32 and 38, LED2
7 and 28 are controlled so that the amount of light incident on the detection PSD 29 and the reference PSD 30 is always equal and constant. Therefore, one of the voltages output from the detection PSD 29 and the reference PSD 30 is used. Signal V2
And V4 can be directly used as a value proportional to the detection position. Therefore, even when there is “play” between the rotating shaft 21 and the rotating plate 23, the rotating shaft 2 is accurately arranged with a configuration that does not require a divider that is expensive and requires complicated adjustment.
1 can be detected, and it can be manufactured with a simple configuration that is inexpensive and requires no adjustment.

FIGS. 5 and 6 show a second embodiment of the present invention. Hereinafter, portions different from the first embodiment will be described. That is, in FIG.
A common connection point with the ED 28 is connected to the rotation region identification terminal P via a comparator 42, and the comparator 42
Are supplied with a reference voltage VK.

As a result, instead of the terminal voltage of the current detection resistor 41 given to the rotation area identification terminal P in the first embodiment, a digital signal S1 as shown in FIG. An output from the comparator 42 can be obtained. As a result, the rotation area of the rotating plate 23 can be identified, so that the same effect as that of the first embodiment can be obtained, and the identification can be performed digitally.

FIGS. 7 and 8 show a third embodiment of the present invention. Hereinafter, portions different from the first embodiment will be described. That is, FIG. 7 shows an electric block configuration, in which the LEDs 27 and 28 are supplied with a constant current from a predetermined DC power supply VC and emit light with a constant light intensity. PS for detection
One output current I1 of D29 is converted to a voltage signal V1 via a current-voltage conversion circuit 43, and then input to each input terminal of an adder 44 and a subtractor 45. In addition, P for detection
The other output current I2 of SD29 is supplied to the current-voltage conversion circuit 46.
After that, the signal is converted into a voltage signal V2, and then input to each input terminal of the adder 44 and the subtractor 45.

The divider 47 generates a voltage signal VDa corresponding to the difference (I1-I2) between the detection currents supplied from the subtractor 45.
(= V1−V2) is divided by the sum (I1 + I2) of the detection currents supplied from the adder 44, that is, the voltage signal VTa (= V1 + V2) corresponding to the total amount of received light, and the result is output as the voltage signal VA. On the other hand, one output current I3 of the reference PSD 30 is converted into a voltage signal V3 via the current-voltage conversion circuit 48, and then input to each input terminal of the adder 49 and the subtractor 50. The other output current I4 of the reference PSD 8 is converted into a voltage signal V4 via the current-voltage conversion circuit 51, and then input to each input terminal of the adder 49 and the subtracter 50. The output terminal of the adder 49 is also connected to the rotation area detection terminal Q.

The divider 52 outputs a voltage signal VDb corresponding to the difference (I3-I4) between the detection currents supplied from the subtractor 50.
(= V3−V4) is divided by the sum (I3 + I4) of the detection currents given from the adder 49, that is, the voltage signal VTb (= V3 + V4) corresponding to the total amount of received light, and the result is output as the voltage signal VB. The subtractor 53 subtracts the voltage signal VB output from the divider 52 from the voltage signal VA output from the divider 47 and outputs the result.
, A voltage signal VD (= VA−VB) corresponding to.

According to the above configuration, the position of the detecting light transmitting portion 25 and the position of the reference light transmitting portion 26 corresponding to the rotation angle θ of the rotating plate 23 are the same as those of the first embodiment.
D29 and the reference PSD 30, respectively. As a result, the rotation angle θ of the rotating plate 23 is calculated from the subtractor 53.
Is obtained (see FIG. 8). And
When the value of the rotation angle θ of the rotating plate 23 is in a region near 0 °, the light from the LED 28 is incident on the reference PSD 30 via the identification light transmitting portion 26a of the reference light transmitting portion 26, Increases the light-receiving current. Therefore, the voltage signal VTb output from the adder 49 also becomes large in this region as shown in FIG. 8, and if this is detected at the rotation region detection terminal Q, the rotation region of the rotating plate 23 can be identified.

FIGS. 9 and 10 show a fourth embodiment of the present invention. Hereinafter, parts different from the third embodiment will be described. That is, in FIG. 9, the output terminal of the adder 49 is connected to the rotation region identification terminal Q via the comparator 54, and the reference input terminal of the comparator 54 is supplied with the reference voltage VK. It has become. As a result, instead of the voltage signal VTb from the adder 49 given to the rotation area identification terminal Q in the third embodiment, the comparator is converted into a digital signal S2 as shown in FIG. The output from 54 can be obtained.
As a result, the rotation area of the rotating plate 23 can be identified. Therefore, the same effect as that of the third embodiment can be obtained, and the identification can be performed digitally.

FIG. 11 shows a fifth embodiment of the present invention. Hereinafter, portions different from the first embodiment will be described. That is, in this embodiment, instead of the identification light transmitting portion 26a provided in the reference light transmitting portion 26 in the first embodiment, FIG.
As shown in (1), identification translucent portions 25c and 25d formed at both ends of the translucent detection portion 25 are wider than other portions.
Is provided. With this configuration, as in the first embodiment, in the region where the rotation angle θ corresponding to both ends of the light transmitting portion 25 for detection is near 0 °, the light incident on the PSD 29 for detection is Is controlled so as to reduce the light projection amount of the LED 27 so as to suppress the increase of the rotation plate 23.
Can be identified, and the same operation and effect as those of the above embodiments can be obtained.

In each of the above embodiments, the discriminating light-transmitting portion 26a having a larger width than other portions is provided as the discriminating light-transmitting portion. However, the present invention is not limited to this.
The same effect can be obtained by forming a translucent portion for identification having a smaller width dimension than other portions.

Further, in each of the above embodiments, two light emitting diodes 27 and 28 are provided as the light emitting elements in correspondence with the detection PSD 29 and the reference PSD 30, respectively. Light may be projected to both PSDs 29 and 30 by the light emitting diodes.

Further, in each of the above embodiments, the optical system is not interposed between the light projecting element and the light receiving element. However, if necessary, the optical system such as a lens may be used. Of course, it may be good.

[0063]

According to the rotation angle detecting device of the present invention, corresponding to the discontinuous angular positions of both ends of the light transmitting portion for detection,
A discriminating light-transmitting part having a width different from that of the other part is formed on either the detecting light-transmitting part or the reference light-transmitting part of the rotating plate. In part,
By changing the level of the total incident light of the light incident through the discriminating light projecting portion with respect to the level of the incident light of the other portion, the rotation position of the rotating plate becomes a discontinuous point portion (rotation angle is 0 ° (In the vicinity), and therefore, an excellent effect that the rotation angle can be accurately detected over the entire circumference of the rotating plate with a simple and inexpensive configuration is obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view.

FIG. 3 is an electrical block diagram.

FIG. 4 is an explanatory diagram showing an output state of a signal.

FIG. 5 is a view corresponding to FIG. 3, showing a second embodiment of the present invention;

FIG. 6 is a diagram corresponding to FIG. 4;

FIG. 7 is a view corresponding to FIG. 3, showing a third embodiment of the present invention;

FIG. 8 is a diagram corresponding to FIG. 4;

FIG. 9 is a view corresponding to FIG. 3, showing a fourth embodiment of the present invention;

FIG. 10 is a diagram corresponding to FIG. 4;

FIG. 11 is a view corresponding to FIG. 1, showing a fifth embodiment of the present invention.

FIG. 12 is a diagram corresponding to FIG. 1 showing a conventional example.

FIG. 13 is an electrical block diagram.

FIG. 14 is a diagram corresponding to FIG. 4;

[Explanation of symbols]

21 is a rotating shaft, 23 is a rotating plate, 25 is a light transmitting part for detection, 2
5c, 25d and 26a are transmissive parts for identification, 26 is a transmissive part for reference, 27 and 28 are LEDs (light emitting elements), 29 is a PSD for detection (semiconductor position detecting element for detection), and 30 is a P for reference.
SD (reference semiconductor position detecting element), 31, 33, 3
7, 39, 43, 46, 48 and 51 are current-voltage conversion circuits, 32, 38, 44 and 49 are adders, 34, 45 and 5
0 is a subtractor, 35 and 40 are feedback circuits, 36 is a reference voltage generation circuit, 41 is a current detection resistor, 42 and 54 are comparators,
7, 52 are dividers.

Claims (1)

(57) [Claims] 1. A rotating plate attached to a rotating shaft, a reference light-transmitting portion having a constant width and formed in a circular shape with a predetermined radius on the rotating plate, and a rotating plate extending along the circumferential direction of the rotating plate. A constant-width detection light-transmitting portion formed in a shape in which the distance from the center of rotation continuously changes, and a light-emitting element that emits light toward the reference light-transmitting portion and the detection light-transmitting portion, A reference semiconductor position detection element that is arranged to face the light emitting element with the rotating plate interposed therebetween, receives light transmitted through the reference light transmitting unit, and detects a light receiving position in a radial direction of the rotating plate, A semiconductor position detecting element for detection, which is arranged to face the light emitting element with the rotating plate interposed therebetween, receives light transmitted through the light transmitting unit for detection, and detects a light receiving position in a radial direction of the rotating plate; These reference semiconductor position detecting element and detecting semiconductor position detecting element Calculating means for calculating the rotation angle of the rotating plate based on the received light signals, wherein the rotating plate corresponds to a discontinuous angular position of both end portions of the light transmitting portion for detection. A rotation angle detecting device, wherein an identification light-transmitting portion having a width different from that of the other portion is formed on one of the detection light-transmitting portion and the reference light-transmitting portion.