JPS63151807A - Angle detector - Google Patents

Abstract

PURPOSE:To detect an angle with high accuracy without necessity for forming a large number of light pervious parts, by providing a light receiving element equipped with a light receiving surface having a length almost equal to the interval between the light pervious parts in the peripheral direction thereof and leading out the electric signal corresponding to a light receiving position. CONSTITUTION:A light source 8 is fixed on one side of a rotary member 7 and a light receiving element 9 is fixed on the other side thereof. The member 7 is formed into a disc shape and a large number of through-holes 12 are formed on the imaginary circle 11 thereof at an equal interval. The element 9 is arranged directly under the imaginary circle 11 and the length L thereof along the imaginary circle 11 is made almost equal to the mutual interval between the adjacent through-holes 12. The element 9 receives the light from a light source 8 through the through-holes 12 to lead out the electric signal corresponding to a light receiving position and, therefore, the angular position between the through-holes 12 can be detected. When the light receiving position moves on the light receiving surface of the element 9 with the angular displacement of the member 7, the output of the element 9 gradually increases and decreases and, by counting the number of rotations of the cyclical change of said output, the number of the through-holes 12 passing the light receiving surface 9 can be detected. By this method, without unnecessarily increasing the number of the through-holes 12, the angular position of the member 7 within a 360 deg.-range can be detected with high accuracy.

Description

TECHNICAL FIELD The present invention relates to an angle detection device that can be advantageously implemented, for example, for detecting the steering angle of a motor vehicle.

Background technology A typical prior art is shown in FIG.

The steering wheel 1 rotatably driven by the steering wheel of the automobile includes:
A disc-shaped rotating member 2 made of a light-shielding material is fixed.

The zero rotation member 2 has through holes 3 formed at equal intervals in the circumferential direction, and a light H4 is provided on one side of the rotation member 2, and a light receiving element 5 is provided on the other side. Light from the light source 4 passes through the through hole 3 and is detected by the light receiving element 5. By counting the number of times the light is received by the light receiving element 5, the angle of the rotating member 2, and thus the steering wheel 1, can be detected.

Problems to be Solved by the Invention In the prior art shown in FIG. 11, in order to detect the angle of the steering wheel 1 with high precision, it is necessary to make the mutual spacing of the through holes 3 close. However, due to processing restrictions, the mutual spacing between the through holes 3 cannot be made too small.

An object of the present invention is to provide an angle detection device that can detect angles with high precision.

Means for Solving the Problems The present invention comprises a rotating member in which transparent parts are formed at equal intervals in the circumferential direction around the axis of rotation and made of a light-shielding material, and light is irradiated from one side of the rotating member. A light source, a light receiving element disposed on the other side of the rotating member, having a light receiving surface having a length approximately equal to the circumferential interval of the light transmitting portion, and deriving an electrical signal corresponding to the light receiving position, and an output from the light receiving element. in response to
The angle detecting device is characterized in that it includes means for counting the number of periodic changes of gradual increase or decrease in the output and detecting the angular position between the transparent parts.

According to the present invention, light from the light source passes through the light-transmitting portion formed in the rotating member and is detected by the light-receiving element. This light-receiving element includes a light-receiving surface having a length approximately equal to the circumferential interval of the light-transmitting portions, and derives an electrical signal corresponding to a position at which light is received from a light source having the light-transmitting portions. The light-receiving position moves on the light-receiving surface with the angular displacement of the rotating member, and the output of the light-receiving element gradually increases or decreases. The number of can be detected. However, since the output of this light receiving element derives an electrical signal representing the receiving position of the light from the light source via the light transmitting portion, it becomes possible to detect the angular position between the light transmitting portions. In this way, it is possible to detect the angle with high precision without the need to form an unnecessarily large number of transparent parts.

Embodiment FIG. 1 is an overall perspective view of an embodiment of the present invention. A rotating member 7 is fixed to the steering shaft 6.

On one side of the rotating member 7, a light source 8 is disposed at a fixed position W1. In this light source 8, a light receiving element 9.10 is provided at a fixed position on the other side of the zero-rotation member 7, which is realized by, for example, a light emitting diode.

The rotating member 7 is made of a light-shielding material and has a disc shape, and is arranged on a virtual circle 11 centered on the axis of the steering shaft 6.
A plurality of transparent holes 12 are formed at equal intervals. At a position radially inward from the virtual circle 11, there is a virtual circle 1
3, a single through hole 14 is formed in the circumferential direction. The light receiving element 9 receives the light from the light source 8 through the through hole 12,
Further, the light receiving element 10 receives light from the light source 8 through the through hole 14 . Based on the output of the light receiving element 9, the angular position of the rotating member 7 within 360 degrees can be detected, and the rotation speed of the rotating member 7 exceeding 360 degrees can be detected using another light receiving element 10. It becomes possible.

FIG. 2 is a simplified perspective view of a steering system of a motor vehicle in which an angle detection device 15 according to the invention shown in the plSi diagram is installed. Steering wheel 16 operated by the driver
is fixed to the steering shaft 6, and an angle detecting device 15 shown in FIG. 1 is provided in the middle of the steering shaft 6. By the angular displacement of the steering shaft d, the wheels 17, which are the front wheels or rear wheels of the automobile, are angularly displaced and steered.

FIG. 3(1) is a plan view showing the arrangement of the rotating member 7 and the light receiving element 9, and FIG. 3(2) is a plan view showing the arrangement of the rotating member 7 and the light receiving element 9.
FIG. The light receiving element 9 is a virtual circle 1
1, and the length L along this virtual circle 11 is selected to be approximately equal to the distance between adjacent through holes 12. Although the light receiving element 9 does not necessarily have to be formed with its light receiving surface curved along the virtual circle 11, as in the illustrated embodiment, the light receiving surface is formed with the light receiving surface curved along the virtual circle 11. By doing so, it is possible to linearly derive the angle detection output.

FIG. 4 is a sectional view of the light receiving element 9. This light receiving element 9
A semiconductor 20 includes a light receiving surface 19 that receives light 18 from the light source 8 through the through hole 12, a common electrode 21 provided on the surface of the semiconductor 20 opposite to the light receiving surface 19, and a semiconductor 20 on the side of the light receiving surface 19. It has individual electrodes 22 and 23 arranged at both ends along the virtual circle 11 described above.

The length of the individual electrodes 22' and 23 is L, the distance between the electrode 22 at the position where the light 18 is received is X, and the length of the individual electrodes 22' and 23 is
When the current flowing between electrodes 21 and 22 is denoted by {circle around (2)}, and the current flowing between electrodes 21 and 23 is rll, the formula m1 and the second formula hold.

I, = K ・−Φ ・
...(2)L Here, K is a proportionality constant, and Φ indicates the incident light intensity of the light 18.

The difference C between these currents rA and I8 is as shown in the third equation, and the sum thereof is as shown in the f:tS4 equation.

D = IA ten I. = toΦ...(4
) Calculating the ratio E based on the third and fourth equations, the fifth
The formula becomes

This ratio E depends on the intensity Φ of the light 18 and the light 18
The value corresponds to the light receiving position X. Therefore, current flows from the electrodes 22 and 23 of the light receiving element 9.

It is understood that the received light value W1x can be detected by calculating I8 according to the fifth equation.

The operation of the light receiving element 9 will be explained with reference to FIGS. 5 and 6. As shown in FIG. 5(1), when the light receiving element 9 is located between the through holes 12 of the rotating member 7, the currents rA and r8 of the electrodes 22 and 23 shown by the third equation above are The difference C has a maximum value v1 as shown in the PI36 diagram.

The state in which the rotating member 7 is angularly displaced as shown by the arrow 25 and one of the through holes 12 is on the light receiving surface 19 of the light receiving element 9 as shown in FIG. 5(2) is shown in FIG. This light reception value 1fi26 is as shown by arrow 925.
The difference C gradually decreases linearly as it moves in the direction of .

When the light receiving value ra26 reaches near the end position of the light receiving surface 19 of the light receiving element 9 as shown in FIG. 5(3), the difference C in the output of the light receiving element 9 becomes a value close to the minimum value v2. In this way, the current value !i of the difference C corresponding to the position θ1 of the received light value fi2(3) is obtained. When the total number of through holes 12 is set to no, the angle θ1 is determined by the current value Ii as shown in the sixth equation. You can ask for it.

! Figure #7 shows electrical NIJ related to light receiving element 9.10.
It is a block diagram showing f&. The output from the light receiving element 10 is amplified by an amplifier circuit 28, waveform-shaped by a comparator circuit 29, and sent from a line 30 to a processing circuit 31 realized by a micro combinator or the like.

The waveform of the electrical signal applied from the line 30 to the processing circuit 31 is as shown in FIG. 8(1), and one pulse is obtained for each rotation of the rotating member 7.

The output from the electrodes 22 and 23 of the light receiving element 9 is on the line 32.
．． 33 and applied to the comparison circuit 34.

The comparator circuit 34 calculates the difference C shown in the third equation described above, and the difference C is converted into a digital value by the analog/digital converter 35 and input to the processing circuit 31.

The output of the comparison circuit 34 is as shown in FIG. 8(2). This output waveform is a waveform obtained when the rotating member 7 is rotated in the direction of the arrow 25, as shown in FIG. 9, the subtraction circuit 34 obtains a waveform that gradually increases with the angular displacement, as shown in FIG.

The output of the subtraction circuit 34 is also applied to a differentiation circuit 36 for differentiation, and the differentiation output is as shown in FIG. 8(3). The output of this differentiating circuit 36 is given to a comparator circuit 37 where it is shaped into a waveform. The output of the comparison circuit 37 is as shown in FIG. 8(4).

The output of the comparison circuit 37 is given to the processing circuit 31.

The output from the photodetector 9 via line 32.33 is also
The signal is applied to the adder circuit 38, and the above-mentioned equation 14 is calculated.

The output of the adder circuit 38 is applied to an analog/digital converter 39 and converted into a digital value, and the digital value is output to the processing circuit 31. The processing circuit 31 derives from a line 40 an electrical signal representing the direction of rotation of the rotating member 7, and from a line 41 an electrical signal representing the angle of the rotating member 7. In the processing circuit 31, the light receiving element 10
The number of times the through hole 14 has been detected, that is, the number of rotations of the rotating member 7 can be counted by receiving a signal via the line 30 from the comparing circuit 29 corresponding to the output of the rotary member 7 .

The operation will be explained with reference to FIG. Moving from step 11 to step n2, the difference C between the current values from the electrodes 22 and 23 of the light receiving element 9 is calculated and determined.

Furthermore, the sum may be calculated and normalized as shown in the formula #&5 above.If the current value which is this difference C is Ii as mentioned above, then the current value at the previous sampling time Ii -1 is subtracted, and it is determined in step n3 whether or not there is a gradual increase. In step n3, if it is determined that it is gradually increasing, the process moves to step n4, and 7 lag R is set as "+1", assuming that it is a regular pine tree.On the contrary, if it is determined that it is gradually decreasing, , step n5
It is determined that the wheel is rotating in the opposite direction, and 7 lag R is set to "-1".

In step n6, it is determined whether the waveform of the rising edge of the pulse corresponding to the output of the light receiving element 10 has been obtained.
If so, the process moves to step n7 and the contents of the counter AC are reset to zero.

In step n8, it is determined whether a rising edge of the differential waveform passed from the differentiating circuit 36 to the comparing circuit 37 has been obtained, and if the rising edge of the differential waveform has been obtained, in step n9, the stored contents of 7 lag R are stored in the counter AC. Add up +1 or -1. In this way, the count value of the through hole 12 is stored in the counter AC with the position of the through hole 14 as a reference.

In step nlo, the seventh formula is calculated based on the contents of the counter AC, and the eighth formula is calculated in conjunction with the result of the sixth formula.

θ2 = −X AC...(7)...(8) Stella 2nll Then, a signal representing the rotation direction is sent from line 40, that is, step n4. 7 by n5
A signal corresponding to the polarity of the lag R is derived, and the line 41
A signal representing the angle θ obtained by the eighth equation is derived from .

In place of the through-holes 12.14 formed in the rotating member 7, a light-shielding paint is selectively formed on the surface of a plate-shaped body made of a transparent synthetic resin material, for example, and holes 12.14 are formed at positions corresponding to the through-holes 12.14. The rotating member may be constructed by not applying the light-shielding paint, or the light-shielding member may be constructed using other configurations.

Effects As described above, according to the present invention, it is possible to detect the angle with high precision based on the output of the light receiving element without increasing the number of light transmitting parts.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an angle detection device 15 according to an embodiment of the present invention, Fig. 2 is a simplified optical illusion diagram of a steering system of an automobile equipped with an angle detection device 16, and Fig. 3 is a rotating member 7 and a light receiving device. Element 9
FIG. 4 is a cross-sectional view of the light receiving element 9,
FIG. 5 is a plan view showing the light receiving operation state of the light receiving element 9 as the rotating member 7 rotates, FIG. 6 is a diagram showing the output waveform of the light receiving element 9 corresponding to the operation shown in FIG. 5, and FIG. is a block diagram showing the electrical configuration related to the light receiving element 9-10, FIG. 8 is a waveform diagram for explaining the operation of the electrical configuration shown in FIG. 7, and FIG. 8 is a diagram showing the output waveform from the subtraction circuit 34 when the rotation is in the opposite direction to that shown in FIG. 8, and FIG.
The chart, FIG. 11, is a perspective view of the prior art. 6... Steering shaft, 7... Rotating member, 8... Light source, 9
, 10... Light receiving element, 12.14... Through hole, 19.
... Light receiving surface, 20 ... Semiconductor, 21 ... Common electrode,
22.23...Individual electrode

Claims (1)

[Claims] A rotating member in which transparent parts are formed at equal intervals in the circumferential direction around the axis of rotation, and is made of a light-shielding material, a light source that irradiates light from one side of the rotating member, and arranged on the other side of the rotating member, A light-receiving element that is provided with a light-receiving surface having a length approximately equal to the circumferential interval of the light-transmitting part and that derives an electrical signal corresponding to the light-receiving position, and a period of gradual increase or decrease in the output in response to the output from the light-receiving element. 1. An angle detection device comprising means for counting the number of times the target changes and detecting the angular position between the transparent parts.