JPH085405A - Potentiometer - Google Patents

Abstract

PURPOSE:To prolong the life and prevent noise generation by making a potentiometer have a structure in which no sliding part is used. CONSTITUTION:A potentiometer is provided with a circular resistor which is installed in a substrate 2 concentrically with a rotary center of a rotary axis 4 and has a cut part in a part, a circular conductor which is installed concentrically with the resistor at a prescribed gap to the inner circumference of the resistor, and a circular photoconductor which is installed in the gap between the conductor and the resistor and becomes an insulating material with high resistance in the condition in which no light is radiated and becomes a conductive material with low resistance in the condition in which light is radiated. The potentiometer is provided also with a light-guiding member 5 to guide light rays emitted out of an electroluminescent diode 10 in order to radiate the light rays to a site corresponding to the rotary angle of the rotary axis 4 in the photoconductor, the diode 10 is installed so as to rotate unitedly with the rotary axis 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a potentiometer for detecting a rotation angle of a rotary shaft based on a change in resistance value.

[0002]

2. Description of the Related Art A potentiometer of this kind is provided with a ring-shaped resistor having a notch in a part thereof on a fixed side substrate concentrically with the center of rotation of a rotary shaft, and in conjunction with the rotation of the rotary shaft. A sliding member made of a conductive material that slides on the resistor is provided. In this configuration, when a constant voltage is applied to both ends of the resistor, the magnitude of the voltage between the sliding member and one end of the resistor changes in proportion to the rotation angle of the rotating shaft. Therefore, the rotation angle of the rotary shaft can be detected by measuring the voltage between the sliding member and one end of the resistor.

[0003]

However, in the above conventional structure, the sliding member slides on the resistor, so that the resistor may be worn by the sliding member when the number of times of use increases. However, the characteristics of the resistor may change and the detection accuracy may deteriorate, resulting in a short service life. Further, in the above-described conventional configuration, wear powder is generated when the resistor wears, and the wear powder makes the contact between the sliding member and the resistor unstable, which causes a problem that noise is generated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a potentiometer capable of prolonging its life and preventing the generation of noise.

[0005]

A potentiometer according to the present invention includes a rotary shaft and a ring-shaped resistor provided on a fixed side concentrically with a rotation center of the rotary shaft and having a cutout portion. , Provided with an annular conductor concentrically provided on the inner circumference or the outer circumference of the resistor with a predetermined gap, and in a state where light is not radiated provided in the gap between the conductor and the resistor. A high-resistance insulating member is provided with a ring-shaped photoconductor having a characteristic that a portion irradiated with light becomes a low-resistance conductive member, and is provided so as to rotate integrally with the rotating shaft from a light source. It is characterized by comprising light guide means for guiding the emitted light to irradiate a portion of the photoconductor corresponding to a rotation angle of the rotation shaft.

In this structure, the light source is provided at a position corresponding to the rotation center of the rotary shaft on the fixed side, and the light guiding means reflects the light emitted from the light source to the outer peripheral side in the radial direction. However, it is preferable that the photoconductor is constituted by a reflecting member that irradiates the photoconductor. Further, it is an even more preferable configuration that the reflecting member is configured by a prism.

[0007]

According to the above-mentioned means, the light emitted from the light source by the light guiding means is rotated by the light guide means with respect to the ring-shaped photoconductor provided between the ring-shaped resistor and the ring-shaped conductor. By irradiating the part corresponding to the rotation angle so that the irradiated part becomes a low resistance conductive member, if a constant voltage is applied to both ends of the resistor, the conductor and one end of the resistor The magnitude of the voltage between the two changes in proportion to the rotation angle of the rotating shaft. Therefore, the rotation angle of the rotating shaft can be detected by measuring the voltage between the conductor and one end of the resistor. In the case of this configuration, the light guide means is only configured to irradiate the light on the portion of the photoconductor corresponding to the rotation angle of the rotation axis, and the conventional sliding member does not exist. Therefore, the resistor is not worn, so that the life can be extended, and since no abrasion powder is generated, the generation of noise can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, in FIG. 1 showing a schematic vertical cross section of a potentiometer, a potentiometer main body 1 is composed of a disk-shaped substrate 2 made of an insulating material and a cup-shaped case 3. The case 3 is fitted and fixed to the outer peripheral portion of the substrate 2 so as to cover the upper side of the substrate 2. A rotating shaft 4 is rotatably supported at the center of the upper wall portion 3a of the case 3 so as to be rotatable. The upper end of the rotary shaft 4 projects above the case 3. A light guide member 5 as a light guide means is attached to the lower end of the rotary shaft 4 in the case 3 so as to rotate integrally with the rotary shaft 4. The light guide member 5 will be described in detail later.

Further, as shown in FIG. 2, an annular resistor 7 having a notch 6 in a part thereof is provided on the peripheral portion of the upper surface of the substrate 2 concentrically with the rotation center of the rotary shaft 4. ing. An annular conductor 8 is concentrically provided on the inner periphery of the resistor 7 with a predetermined gap. An annular photoconductor 9 is provided in the gap between the conductor 8 and the resistor 7. The photoconductor 9 is made of, for example, CdS or the like, is an insulating member having a high resistance in a state where it is not irradiated with light, and has a characteristic that a portion irradiated with a light becomes a conductive member having a low resistance. Have In this case, the photoconductor 9 is configured such that its inner peripheral portion and outer peripheral portion contact (connect) with the outer peripheral portion of the conductor 8 and the inner peripheral portion of the resistor 7, respectively.

Further, for example, a light emitting diode 10 is provided as a light source at the central portion of the upper surface of the substrate 2 (that is, the portion corresponding to the center of rotation of the rotary shaft 4). As shown in FIG. 1, the light emitting diode 10 emits light upward, in this case, along the axial direction of the rotating shaft 4.

Now, the light guide member 5 will be described in detail. The light guide member 5, as shown in FIGS. 1 and 3,
This is a thick plate-like member having a substantially rectangular shape as a whole, and the lower end of the rotary shaft 4 is fitted and fixed in a fitting hole 11 formed in the upper left part of FIG. As a result, the rotating shaft 4
When is rotated, the light guide member 5 is configured to rotate integrally with the rotary shaft 4 about the rotary shaft 4 (fitting hole 11). A circular hole 12 having an inner diameter slightly larger than the outer diameter of the light emitting diode 10 is formed in the left portion of the lower surface of the light guide member 5.
The light emitting diode 10 is configured to be housed and arranged in the interior 2. In this case, when the light guide member 5 is rotated, a gap is formed between the circular holes 12 so that the light emitting diode 10 does not come into contact with the inner peripheral portion of the circular hole 12. Further, as shown in FIG. 1, an inclined surface portion is formed on the inner bottom portion of the circular hole 12, and a reflection surface 12a is formed on this inclined surface portion. The reflection surface 12a is configured to reflect the light emitted from the light emitting diode 10 in the radial direction (rightward in FIG. 1).

An elongated slit-shaped opening 13 extending in the radial direction is formed on the right side of the lower surface of the light guide member 5 so as to communicate with the circular hole 12. This opening 1
As shown in FIG. 1, an inclined surface portion is formed on the inner bottom portion of 3, and a reflection surface 13a is formed on this inclined surface portion. In this structure, the light reflected in the radial direction (rightward in FIG. 1) by the reflecting surface 12a of the circular hole 12 is reflected by the reflecting surface 13a of the opening 13 and is reflected downward in FIG. As shown in FIG. 2, a slender strip-shaped hatched region P is illuminated by the reflected light. The shaded (irradiated) region P is configured to rotate according to the rotation of the rotation shaft 4, whereby the light emitted from the light emitting diode 10 is reflected toward the outer peripheral side in the radial direction, The photoconductor 9 is configured to be irradiated to a portion corresponding to the rotation angle of the rotation shaft 4. In the case of this configuration, the circular hole 12, the reflection surface 12a, the opening 13, and the reflection surface 13a of the light guide member 5 form a reflection member.

On the other hand, terminals 14 and 15 are connected to both ends of the resistor 7 as shown in FIG. 2, and these terminals 14 and 15 penetrate the substrate 2 as shown in FIG. And is projected downward (only the terminal 14 is shown in FIG. 1). Further, a terminal 16 is connected to an intermediate portion of the conductor 8 as shown in FIG. 2, and the terminal 16 penetrates through the substrate 2 and projects downward as shown in FIG. Further, the two terminals 17 and 18 led out from the light emitting diode 10 penetrate the substrate 2 and project downward as shown in FIG.

Next, the operation of the above configuration will be described. First,
A constant DC voltage is applied to both ends of the resistor 7 via the terminals 14 and 15, and a necessary driving voltage is applied to the light emitting diode 10 via the terminals 17 and 18 so that the light emitting diode 1
0 is emitted. As a result, as shown in FIG. 1, the light from the light emitting diode 10 is reflected by the reflecting surface 12a of the circular hole 12 and travels in the radial direction (to the right in FIG. 1).
This light is reflected by the reflecting surface 13a of the opening 13 and travels downward in FIG. 1 to illuminate the shaded area P as shown in FIG. The shaded area P is the rotation axis 4
Rotates according to the rotation of.

Here, the portion of the photoconductor 9 in the shaded (irradiated) region P becomes a conductive member having a low resistance due to the irradiated light, and the remaining portion of the photoconductor 9 is high. Since it is an insulating member of resistance, the magnitude of the voltage between the conductor 8 and one end of the resistor 7 changes in proportion to the rotation angle of the rotation shaft 4. In this case, the voltage between the conductor 8 and one end of the resistor 7 is the constant voltage applied to both ends of the resistor 7 and the distance (resistance) between one end of the resistor 7 and the region P. , Distance between the other end of the resistor 7 and the region P (resistance)
It is the voltage divided by. Therefore, the rotation angle of the rotary shaft 4 can be detected by measuring the voltage between the terminals 16 and 14 (or the terminal 15).

In the case of this embodiment having the above-mentioned structure,
Only the light guide member 5 irradiates the light from the light emitting diode 10 to the portion (specifically, the shaded area P) of the photoconductor 9 corresponding to the rotation angle of the rotation shaft 4. Therefore, the sliding member of the conventional configuration can be configured not to exist, since the resistor will not be worn, the life can be significantly extended, and since abrasion powder of the resistor is not generated, Generation of noise can be eliminated.

FIG. 4 shows a second embodiment of the present invention, and the difference from the first embodiment will be described. still,
The same parts as those in the first embodiment are designated by the same reference numerals.
In the second embodiment, the reflection member of the light guide means includes the circular hole 12, the reflection surface 12a, the opening portion 13 of the light guide member 5,
Instead of the reflecting surface 13a, the prism 19 is used. Specifically, the prism holding member 20 which replaces the light guide member 5 is formed with a circular hole 21 for housing the light emitting diode 10 and a slit-shaped housing hole 22 for housing the prism 19. A concave portion 19a is formed on the left end portion of the prism 19 in FIG. 4 so as to form a part of a circular hole 21 that accommodates the light emitting diode 10.

In this structure, the prism 19 is made of a light-transmissive member, and is transparent to air on the inclined surface 19b at the upper left portion in FIG. 4 and the inclined surface 19c at the upper right portion in FIG. The light is totally reflected due to the difference in the refractive index with the member. As a result, the light emitted from the light emitting diode 10 is transmitted to the inclined surface 19 b of the prism 19.
4 and then travels in the radial direction (to the right in FIG. 4). Further, this light is reflected from the inclined surface 19c of the prism 19 and travels downward in FIG. 4 to irradiate the shaded area P (see FIG. 2). Is configured. In this case, the prism 19 and the prism holding member 20 constitute a light guide unit. The configuration other than the above is the same as the configuration of the first embodiment. Therefore, also in the second embodiment described above, it is possible to obtain substantially the same operational effects as in the first embodiment.

In each of the above embodiments, the annular conductor 9 is provided on the inner periphery of the resistor 7 with a predetermined gap, but instead of this, the outer periphery of the resistor 7 is provided with a predetermined gap. A ring-shaped conductor may be provided. In each of the above embodiments, the light emitting diode 10 is provided in the center of the substrate 2. However, the present invention is not limited to this, and a light source capable of illuminating the entire upper surface of the substrate 2 is provided on the inner surface of the top of the case 3. A light shielding plate is provided between the light source and the substrate 2, and the light shielding plate is attached to the rotating shaft 4 so as to rotate integrally.
Further, a slit for irradiating the portion of the photoconductor 9 corresponding to the rotation angle of the rotation shaft (the portion corresponding to the shaded area P) with the light from the light source is formed in the light shielding plate. Is also good. Also with this configuration, it is possible to obtain substantially the same operational effects as those of the above-described respective embodiments.

[0020]

As is clear from the above description, the present invention provides a light guide means for a light source for a ring-shaped photoconductor provided between a ring-shaped resistor and a ring-shaped conductor. By irradiating the site corresponding to the rotation angle of the rotary shaft with the emitted light, the site is configured as a low-resistance conductive member. Therefore, the voltage between the conductor and one end of the resistor is measured. Thus, the rotation angle of the rotation axis can be detected, and in the case of this configuration, the light guiding means is configured to irradiate light to a portion of the photoconductor corresponding to the rotation angle of the rotation axis. Since the sliding member of the conventional structure does not exist, it has an excellent effect that the life can be extended and the generation of noise can be prevented.

Further, in the case of the above construction, the light source is provided at a position corresponding to the rotation center of the rotation shaft on the fixed side, and
Since the light guiding means is composed of the reflecting member that irradiates the photoconductor with the light emitted from the light source being reflected toward the outer peripheral side in the radial direction, it can be easily realized with a simple configuration. Furthermore, if the reflecting member is composed of a prism,
The configuration can be made simpler and have better manufacturability.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention.

FIG. 2 is a top view of the substrate

FIG. 3 is a bottom view of a case and a light guide member.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

[Explanation of symbols]

2 is a substrate, 3 is a case, 4 is a rotating shaft, 5 is a light guide member (light guiding means), 6 is a notch, 7 is a resistor, 8 is a conductor,
9 is a photoconductor, 10 is a light emitting diode (light source), 12 is a circular hole, 13 is an opening, 13a is a reflecting surface, 14, 15,
Reference numerals 16, 17, and 18 denote terminals, 19 denotes a prism, and 20 denotes a prism holding member.

Claims (3)

[Claims] 1. A rotating shaft, an annular resistor provided concentrically with the rotation center of the rotating shaft on the fixed side, and having a notch in part, and a predetermined gap on the inner or outer circumference of the resistor. A circular conductor that is concentrically provided through the conductor and a gap between the conductor and the resistor, and is a high-resistance insulating member that is irradiated with light when not irradiated with light. A ring-shaped photoconductor having a characteristic that a closed portion serves as a low-resistance conductive member, and the light emitted from a light source, which is provided so as to rotate integrally with the rotation shaft, among the photoconductor. A potentiometer comprising: a light guide unit that guides the light to irradiate a portion corresponding to the rotation angle of the shaft. 2. The light source is provided at a position corresponding to the center of rotation of the rotary shaft on the fixed side, and the light guiding means reflects the light emitted from the light source to the outer peripheral side in the radial direction. The potentiometer according to claim 1, wherein the potentiometer comprises a reflecting member that irradiates the conductor. 3. The potentiometer according to claim 2, wherein the reflecting member is a prism.