JP3535415B2 - Potentiometer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous rotation type potentiometer used for detecting a rotational position of a robot arm or the like, and more particularly to a technique for expanding an effective electrical angle of detection.

[0002]

2. Description of the Related Art Conventionally, in a potentiometer for detecting a rotational position, since terminal ends of both ends of the resistor are on the same circle, it is necessary to provide a gap between the terminals so as not to short-circuit these terminals. Due to this gap, a dead band in which an output cannot be obtained is generated, so that the effective electrical angle (the angle at which the rotational position of the moving terminal can be detected) cannot be set to 360 °. In addition, since the terminal terminal itself has an area, the effective electrical angle becomes smaller by the amount of the space. In this way, when the terminal terminals at both ends of the resistor are provided on the same circle, the effective electrical angle of the continuously rotating potentiometer is determined by the ratio between the distance between the terminal terminals and the radius of the resistor. If the distances are the same, the radius of the resistor must be increased to widen the effective electrical angle. Therefore, it is necessary to increase the size of the resistor and the potentiometer body. Further, there is a type of potentiometer called a wire wound type, but when the moving terminal makes several revolutions, it hits a mechanical limit, and there is a limit to the number of revolutions that can be continuously detected.

[0003]

As described above, in the conventional potentiometer, the overall shape becomes large, and it is necessary to provide a gap for preventing short circuit between the terminal terminals along the circumferential direction of the resistor. However, there is a problem that the effective electrical angle cannot be set to 360 °, the detectable rotation angle range is restricted, and continuous rotation detection is not easy.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to eliminate the dead angle of the rotational position detection so that the effective electrical angle can be set to 360 °, and the continuous rotational position in all directions. It is an object of the present invention to provide a potentiometer that can perform detection and that can reduce the overall shape.

[0005]

In order to achieve the above object, the present invention is directed to the position of a moving terminal depending on the resistance value from one end of the resistor to the moving terminal position by sliding the moving terminal on the resistor. In the potentiometer that detects
Resistor is formed in a spiral shape on the disk, moving terminal,
It is provided on the rotating body with the center of the spiral shape as the axis ,
The moving terminals are on the same radius passing through the center of the spiral shape.
And pass through the 0 ° and 360 ° ends of the spiral shaped resistor.
It is divided into two parts corresponding to each circumference.
The moving terminals are 0 ° and 360 ° of spiral resistors, respectively.
It moves along each circumference passing through each end of the
It is used by switching every half cycle of the antibody .

In the above structure, since the resistor is formed in a spiral shape, the terminal terminals at both ends of the resistor are displaced from the center of the spiral shape in the radial direction, and a short circuit occurs between the terminal terminals in the circumferential direction of the resistor. It is not necessary to provide a gap for prevention. As a result, the effective electrical angle of the potentiometer can be set to 360 ° . Also, the two moving terminals are
Circles passing through the 0 ° and 360 ° ends of the spiral resistor
It moves along the circumference and cuts every half circumference of the spiral resistor.
By replacing it, it can be used in all directions.
The rotation position can be continuously detected, and the moving terminal
Depending on the rotation position of 0 ° and 360 °, potentiometer
The output value of the meter can be identified.

[0007]

Further, it is possible to have a sensor that outputs a position detection signal for each half turn in conjunction with the rotation of the moving terminal, and to switch between the two moving terminals based on this sensor output signal. desirable.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A potentiometer according to an embodiment of the present invention will be described below with reference to the drawings. The potentiometer according to the present embodiment is used for detecting the rotational position of the robot arm or the like.

FIG. 1 shows a schematic configuration of the potentiometer according to this embodiment. On the main body disc 2 of the potentiometer 1, a spirally formed resistor 3 is provided. The terminals 4 and 5 at the start and end of the resistor 3 are displaced from the center of the spiral shape in the radial direction, and the boundaries between these terminals 4 and 5 and the resistor 3 are located at 0 ° and 360 ° in the figure, respectively. It is attached so that it comes to (origin). Body disk 2
A rotary shaft 6 that is rotatable with respect to the main body disk 2 (fixed) is arranged at the center of the spiral shape, and the rotary shaft 6 has inner and outer circumferences at its tip. An arm 9 having two wipers 7 and 8 (moving terminal in claims) is attached. The wipers 7 and 8 are arranged side by side on the same radius passing through the center of the rotary shaft 6, and are configured to rotate while sliding on the resistor 3 in association with the rotation of the rotary shaft 6. The wipers 7 and 8 move on a circle passing through the terminals 4 and 5 of the spiral resistor 3 at 0 ° and 360 °, respectively, and these turn paths 10 and 11 are shown. The relative phase difference between the rotation angle of the rotary shaft 6 to which the arm 9 is attached and the rotation angle of the wipers 7 and 8 attached to the tip of the arm 9 is set to 0 °.

In the potentiometer 1 having the above structure, if the wipers 7 and 8 are now rotated clockwise from the starting end terminal 4 to the terminating terminal 5, they are 0 to 180 °.
The wiper 7 on the inner peripheral side slides on the resistor 3 mainly in the half-round range up to the vicinity, and the wiper 8 on the outer peripheral side mainly slides in the remaining half-circle range from 180 ° to 360 °.
Therefore, the wipers 7 and 8 used for detecting the rotational position are 0 °.
The positions of (360 °) and 180 ° are selectively switched using an electric or mechanical mechanism described later. The length of the resistor 3 from the start terminal 4 or the terminal 5 to the wipers 7 and 8 changes with the rotation of the rotary shaft 6, so that the resistor 3 changes in accordance with the amount of rotation of the rotary shaft 6. The resistance value of changes. Therefore, by applying a voltage between the starting terminal 4 and the terminating terminal 5 of the resistor 3 and detecting the change in the voltage drop between any one of the terminals 4 and 5 and the wiper 7 or 8, the rotary shaft The rotational position of 6 can be detected.

FIG. 2 shows the wipers 7, 8 of the potentiometer 1.
FIG. 3 is a view showing a mechanism for selecting and switching the, and FIG. The mechanism for switching the selection includes a slit plate 21 mounted on the rotary shaft 6 and a position detection sensor 22 for detecting the position of the slit plate 21. The slit plate 21 is cut out by a semicircle corresponding to the angles of 0 ° (360 °) and 180 ° of the resistor 3,
The position detection sensor 22 is provided on the fixed side member 23 and is composed of a large diameter portion 21a and a small diameter portion 21b.
It is composed of a light projecting portion 22b and a light receiving portion 22c which are provided with the slit plate 21a sandwiched therebetween. The light projecting portion 22b and the light receiving portion 22c have a radius 2 of an angle of 0 ° (360 °) of the resistor 3.
It is provided on the surface including a.

Next, the operation of the mechanism for selectively switching the wiper 7 and the wiper 8 configured as described above will be described.
In FIG. 3, in the range of the wiper 7, 8 from the starting terminal 4 to the half circle, only the inner wiper 7 is in contact with the resistor 3 at first (state shown in A), and the wiper 7, 8 is the half circle. As it moves to the vicinity, both wipers 7 and 8 come into contact with the resistor 3 (half-circumference state is shown in B), and both wipers 7 and 8 are in a range reaching the terminal terminal 5 on the remaining half-circle.
From the state where 8 is in contact with the resistor 3, only the outer peripheral wiper 8 is in contact with the resistor 3 (state shown in C). 2 and 3 show the slit plate 21 in a state where it has moved to the vicinity of a half circumference. Now, a case where the rotary shaft 6 and the wipers 7 and 8 rotate clockwise will be described.
, 360 °), the slit plate 21 that rotates integrally with the rotary shaft 6 switches the large diameter portion 21a to the small diameter portion 21b, so that the light from the light projecting portion 22b is transmitted through the slit plate 21.
Therefore, the light is not shielded by the light and is received by the light receiving unit 22c, and the output signal of the position detection sensor 22 is switched from off to on. Further, when the rotation angle passes through the 180 ° position (in the state shown in FIG. 2), the slit plate 21 has the small diameter portion 2
Since the large diameter portion 21a is switched from 1b, the light projecting portion 22b
The slit plate 21 shields the light from the light source, and the light receiving portion 22c does not receive the light.
The output signal of 2 switches from on to off.

In accordance with the output signal of the position detecting sensor 22, the wiper 7 is selectively used as the terminal of the resistor 3 when the rotation angle of the rotary shaft 6 is in the range of 0 ° to 180 °.
In the range of 80 ° to 360 °, the wiper 8 is selectively used. This makes it possible to detect a change in the resistance value (voltage drop value) of the resistor 3 depending on the rotation angle regardless of the rotation angles of the rotation shaft 6 and the wipers 7 and 8. Therefore, the effective electrical angle of the potentiometer 1 is detected. Can be 360 °. Therefore, it is not necessary to increase the size of the potentiometer main body, which has been performed in order to increase the effective electrical angle in the conventional potentiometer, so that the potentiometer main body can be downsized. Further, since there is no dead band for detection, it is possible to detect the rotational position corresponding to continuous rotation.

FIG. 4 shows an electric circuit of the potentiometer 1. The terminal lines of the wipers 7 and 8 of the potentiometer 1 are used as output terminals T1 via the analog switches 32 and 33, and the analog switches 32 and 33 are the position detection sensor 2
On / off control is performed based on the output signal of 2. In addition,
Of the output lines of the sensor 22, the NOT gate 31 is interposed in a line connected to one analog switch 33. Terminals T2 and T connected to both ends of the resistor 3
The detection signal of the potentiometer 1 is output between 3 and the output terminal T1. These terminals T1 to T3 are connected to the terminals of the data input section 35 of the external device. Data input section 35
Has an AD converter 36. With such an electric circuit configuration, the rotation angle of the rotary shaft 6 is 0 ° to 180 °.
In the range (2), the output signal of the position detection sensor 22 is on, so the analog switch 32 is on and the wiper 7 is selectively used. Also, the rotation angle of the rotary shaft 6 is 1
In the range of 80 ° to 360 °, the output signal of the position detection sensor 22 is off, so that the analog switch 33 via the NOT gate 31 is turned on and the wiper 8 is selectively used.

The spiral resistor 3 according to this embodiment will be described below.
A concrete example of is shown. In FIG. 1, the definition of the spiral shape: The radius increases in proportion to the angle from the inner end terminal 4 to the outer end terminal 5. Radius at the start of the spiral (angle θ = 0); r = R Radius at the end of the spiral (angle θ = 2π); r = R + A · 2
Radius at angle θ; r = R + Aθ

Circle inscribed in the spiral: Radius; r = R Arc length; l = Rθ Differentiating the length of the arc by the angle θ, dl / dθ = R

A circle circumscribing the spiral: radius; r = R + 2πA arc length; l = (R + 2πA) θ When the arc length is differentiated by the angle θ, dl / dθ = R + 2
πA

Spiral: Consider a circular arc whose radius changes continuously. Radius; r = R + Aθ If the radius and the length of the arc are differentiated by the angle θ, the length of the circular arc of the spiral is differentiated by the angle θ; dl / dθ
= R + Aθ This is integrated by the angle θ, and 1 = Rθ + (1/2) Aθ ²

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above embodiment, the position detection sensor 2 which is a transmission type optical sensor is used.
Although the rotational positions of the wipers 7 and 8 are detected by using 2, the device for detecting the rotational positions of the wipers 7 and 8 may be a reflection type optical sensor or a contact type such as a limit switch. It may be a detection device.

[0021]

As described above, according to the present invention, since the resistor is formed in the spiral shape, a gap for preventing a short circuit along the circumferential direction of the resistor is provided between the starting end and the terminating terminal at both ends of the resistor. Since it is not necessary to provide it, the blind spot area is eliminated, and the effective electrical angle of the potentiometer can be set to 360 °. Thus, it is possible to widen the effective electrical angle without increasing the diameter of the potentiometer body, it is possible to reduce the size of the potentiometer body. Well
In addition, the two moving terminals are 0
Swirl along each circumference passing through the ends of ° and 360 °
It is used by switching every half circumference of the wound resistor.
By doing so, it is possible to support continuous rotation in all directions.
Rotational position detection can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a potentiometer according to an embodiment of the present invention.

FIG. 2 is a perspective view of an inner peripheral wiper and an outer peripheral wiper switching mechanism of the potentiometer.

FIG. 3 is a top view of the mechanism.

FIG. 4 is an electric circuit diagram of the potentiometer.

[Explanation of symbols]

1 Potentiometer 3 Resistor 4 Starting end terminal ( termination of 0 °) 5 Ending terminal ( termination of 360 °) 7 Wiper (moving terminal) 8 Wiper (moving terminal) 9 Arm (rotating body) 10 Revolving orbit (end of 0 ° ) Circumference passing 11 Rotating orbit (circumference passing the end of 360 °) 22 Position detection sensor (sensor)

Claims (2)

(57) [Claims] 1. A potentiometer for detecting a position of a moving terminal by a resistance value from one end of the resistor to a position of the moving terminal when the moving terminal slides on the resistor, wherein the resistor is a circle. is formed in a spiral shape on the plate, before Symbol mobile terminal, said has a center of a spiral shape provided on the rotary member and the axis, the moving terminal, the same radius on passing through the center of the spiral shape
The end of the spiral resistor at 0 ° and 360 °.
Corresponding to each circumference passing through the edge, it is provided in two
And the two moving terminals are the spiral-shaped resistors, respectively.
Move along each circumference through the 0 ° and 360 ° ends of
And switch between each half-circle of the spiral-shaped resistor
A potentiometer characterized by being used. 2. Each half circumference is interlocked with the rotation of the movable terminal.
Each sensor has a sensor that outputs a position detection signal.
Switching between the two moving terminals based on the output signal
The poten according to claim 1, characterized in that
Schometer.