JP3273457B2 - Motor driven slide type variable resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driven slide type variable resistor, and more particularly to a motor driven slide type variable resistor in which rotation of a motor is transmitted to a movable portion of the variable resistor via a belt with teeth. It relates to a variable resistor.

[0002]

2. Description of the Related Art A motor driven slide type variable resistor has a resistance value which can be adjusted by both a motor driving operation and a manual operation. The rotation of the motor is controlled by a belt wound around a pair of pulleys. Is transmitted to the movable body of the variable resistor. In such a motor driven slide type variable resistor, it is important to reliably transmit the rotation of the motor to the belt via the pulley, and an example of such a power transmission mechanism is proposed in Japanese Utility Model Laid-Open No. 4-77204. .

The motor-driven slide type variable resistor described in the above-mentioned publication has a gear portion formed on the outer peripheral surface of a drive pulley rotated by a motor, and a driven pulley which is opposed to the drive pulley at a predetermined interval. A gear portion is also formed on the outer peripheral surface of the pulley, and a tooth portion meshing with the gear portions of both pulleys is formed on an inner peripheral surface of the belt stretched between the driving pulley and the driven pulley. A movable body having a knob and a slider piece is fixed to the belt, and the slider piece is in sliding contact with the resistor on the resistor substrate. Then, when the operator manually operates the knob of the movable body, the relative position between the slider piece and the resistor changes, and the resistance value is adjusted manually.
Further, when the motor is rotated by an external signal, the rotation rotates the driving pulley, and further, the mesh rotates between the driving pulley and the driven pulley due to the engagement between the gear portion and the tooth portion. The movable body fixed to the belt moves, and the resistance value is adjusted by driving the motor.

[0004]

In the above-described conventional motor-driven slide type variable resistor, when the resistance value is adjusted by driving the motor, after the movable body reaches the end of the movable range. However, if the motor continues to rotate, only the driving pulley continues to rotate with the movable body and the belt stopped, so that the gear portion of the driving pulley rides over the teeth of the belt, causing a problem of generating abnormal noise. At this time, if the belt tension is significantly increased, the gear portion of the driving pulley cannot get over the tooth portion of the belt, and the rotation of the motor can be forcibly locked, but as the belt tension increases, both pulleys Because the rotational torque increases, the operating force when manually adjusting the resistance value becomes too large,
Another problem is that operability is impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances of the prior art, and has as its object to reduce the occurrence of abnormal noise when driving a motor without reducing the operability during manual operation. To provide a type variable resistor.

[0006]

To achieve the above object, the present invention provides a drive pulley having a gear portion on an outer peripheral surface;
A motor for rotating and driving the driving pulley, a driven pulley opposed to the driving pulley at a predetermined interval, and a tensioned member between the driving pulley and the driven pulley, the inner peripheral surface meshing with the gear portion. A belt provided with a tooth portion, a movable body fixed to a part of the belt, a slider piece provided on the movable body, and a resistance substrate slidably contacting the slider piece; A guide member is arranged around the drive pulley in a motor-driven slide type variable resistor whose resistance value is adjusted by a change in a sliding contact position between the slider piece and the resistance substrate accompanying reciprocation of a movable body. The most important feature is that a gap smaller than the toothed dimension of the tooth portion is formed between the guide member and the belt. In the above configuration, it is possible to provide a restricting portion for pressing the belt against the drive pulley on a part of the guide member, and to rotate the guide member around an axis parallel to the rotation axis of the drive pulley. It is also possible to provide as possible.

[0007]

When a guide member is provided around a belt wound around a drive pulley, and a gap smaller than the toothed dimension of the tooth portion of the belt is formed between the guide member and the belt,
At the position where the gap is formed, the outward movement of the belt is regulated by the guide member to be equal to or less than the toothed dimension of the tooth portion. Therefore, when the motor is driven, the movable body fixed to the belt reaches the end of the movable range, and when the rotation of the belt stops, the gear portion of the driving pulley is rotated even if the motor continues to rotate. The driving pulley cannot rotate over the teeth, and the rotation of the driving pulley is prevented by the teeth of the belt regulated by the guide member. In addition, when a regulating portion for pressing the belt against the driving pulley is provided in a part of the guide member,
Engagement of the teeth of the belt with the gears of the drive pulley is ensured. Further, if the guide member is provided rotatably about an axis parallel to the rotation axis of the drive pulley, the guide member also rotates in accordance with the rotation of the belt, so that the guide member hinders the rotation of the belt during manual operation. It will not be.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing the overall configuration of a motor driven slide variable resistor according to one embodiment of the present invention, FIG. 2 is a perspective view of a motor drive unit, and FIG. 3 is an exploded perspective view showing a drive pulley support structure. 4 is an explanatory view showing the positional relationship between the driving pulley and the guide member, FIG. 5 is a cross-sectional view showing an attached state of the guide member, FIG. 6 is an exploded perspective view showing a supporting structure of the driven pulley, and FIG. FIG. 8 is an exploded perspective view of a movable body, FIG. 9 is a side view of a lever, FIG.
0 is a plan view of the slider receiver, FIG. 11 is a rear view of the slider receiver, FIG. 12 is a plan view showing a state where the movable body is being mounted on the belt, and FIG. 13 is along the line AA in FIG. FIG. 14 is a cross-sectional view, FIG. 14 is a plan view showing a state where the movable body has been attached to the belt, and FIG. 15 is a cross-sectional view along the line BB of FIG.

The motor driven slide type variable resistor according to the present embodiment includes a motor driving unit 1 shown in FIG. 2, a pair of covers 2 covering the front and rear surfaces and the bottom surface of the motor driving unit 1, and a motor driving unit 1 shown in FIG. , A pair of holders 3 covering the left and right sides of the motor drive unit 1, a blind plate 4 covering the upper surface of the motor drive unit 1, and a resistance substrate 5 installed facing the motor drive unit 1. Resistors and current collectors (both not shown) are formed on the surface of the resistor substrate 5 to be in sliding contact with the respective slider pieces described later, and positioning holes 5 a are formed on both side edges of the resistor substrate 5. Are drilled. On the other hand, a pair of positioning grooves 2a extending in the longitudinal direction is formed on the inner surface of the cover 2, and the resistor substrate 5 is inserted between the positioning grooves 2a.

As shown in FIG. 2, the motor drive unit 1 includes a metal frame 6, a motor 7 fixed to one end of the frame 6, and a drive pulley 8 fixed to a rotating shaft of the motor 7. A guide member 9 surrounding the drive pulley 8, a driven pulley 10 supported at the other end of the frame 6, a belt 11 stretched relatively loosely between the drive pulley 8 and the driven pulley 10, The frame 6 includes a pair of guide shafts 12 and 13 bridged between both ends of the frame 6 and a movable body 14 that can reciprocate along the two guide shafts 12 and 13. Unitized.

The frame 6 has positioning protrusions 15a.
, A second receiving plate 16 bent at a right angle from the upper end of the left leg 15 shown in the figure, and a first receiving plate facing the second receiving plate 16 at a predetermined interval. 17 and
A support plate 18 that is bent substantially at a right angle from the upper end of the right leg 15 in the drawing, and a pair of upstanding pieces 19 that are bent at a right angle from the first receiving plate 17 and the support plate 18 are formed. Pressed from a plate. Grooves 15b and 19a are formed in the leg piece 15 and the standing piece 19, respectively. The guide shafts 12 and 13 are fixed to the frame 6 by caulking the open ends of the grooves 15b and 19a. In addition, each of the positioning projections 1
5a is engaged with each positioning hole 5a of the resistance board 5, and thus, by regulating the resistance board 5 in the three-dimensional direction by the positioning groove 2a of the cover 2 and the positioning protrusion 15a of the leg piece 15, The resistance substrate 5 is fixed to the frame 6 without using screws or caulking.

As shown in FIG. 3 to FIG.
The support plate 18 is formed with a circular through hole 18a and a rectangular regulating hole 18b, and an upright piece 19 on the right side in the drawing is formed with a locking hole 19b. The motor 7 is screwed to the lower surface of the support plate 18, and the rotating shaft 7 a of the motor 7 passes through the through hole 18 a and protrudes above the support plate 18. Note that the support plate 18 is bent at a slightly acute angle with respect to the leg piece 15, and as a result,
The rotation shaft 7a of the motor 7 attached to the support plate 18 is inclined outward by a predetermined angle with respect to a line perpendicular to the guide shafts 12 and 13 (in the case of the present embodiment, the inclination angle is 1 ° 30). '). On the other hand, a gear portion 8a is formed on the outer peripheral surface of the drive pulley 8, and a flange portion 8b is formed at a lower end of the gear portion 8a. This drive pulley 8 is press-fitted into a rotary shaft 7a of the motor 7.・ It is fixed. here,
The shaft hole of the drive pulley 8 and the rotary shaft 7a are each formed in a D-shaped cross section, and the D-shape ensures that the rotation of the rotary shaft 7a is transmitted to the drive pulley 8. As described above, the driving pulley 8 has the belt 11
The teeth 11 a formed on the inner peripheral surface of the belt 11 mesh with the gear 8 a of the driving pulley 8. At this time, the rotating shaft 7a of the motor 7 is inclined so as to slightly outward with respect to a line perpendicular to the two guide shafts 12 and 13, and the driving pulley 8
Rotates, the belt 11 wound around the driving pulley 8
Since the downward force with the flange 8b always acts on the driving pulley 8, the belt 11 can be reliably prevented from falling off only by forming the flange 8b only at the lower end of the driving pulley 8.

The guide member 9 is formed in a bag shape with an open lower end, and a hole 9a is formed in the upper surface thereof. A first snap claw 9b extending downward is formed on one of the opposed side walls of the guide member 9, and a second snap claw 9c extending upward is formed on the other, respectively. Is formed with a hanging piece 9d slightly shorter than the first snap claw 9b. The width of the first snap claw 9b is set to be slightly smaller than the restriction hole 18b of the support plate 18, and similarly, the second snap claw 9b
The width of the snap claw 9c is determined by the locking hole 1 of the upright piece 19.
It is set slightly smaller than 9b. Further, the guide member 9 is formed with a pair of regulating portions 9e facing each other via the first snap claws 9b.
Are formed in a curved shape.

The guide member 9 constructed as described above is put on the driving pulley 8 and the belt 11 wound therearound. The guide member 9 locks the first snap claw 9b in the regulating hole 18b, and simultaneously holds the second snap. By snapping the claws 9c into the locking holes 19b, respectively, as shown in FIG.
The rotary shaft 7a is rotatably mounted on the support plate 18 of the frame 6 with the rotary shaft 7a protruding from the support plate 18. That is, the first
And the second snap claws 9b and 9c are provided with the restriction holes 1 respectively.
Since the guide member 9 can be moved by a small amount in the width direction with respect to the hole 8b and the locking hole 19b, the guide member 9 can rotate by a small angle around the hole 9a. The belt 11 is stretched around the driven pulley 10 through the space between the first snap claw 9b and both regulating portions 9e, and is in contact with both regulating portions 9e in the vicinity of the exit of the guide member 9. Belt 1 in the regulation part 9e
1 is pressed inward, the tooth portion 1 of the belt 11 is pressed.
1a is reliably engaged with the gear portion 8a of the drive pulley 8. At this time, since the guide member 9 is rotatably mounted on the support plate 18, if the belt 11 is strongly pressed against the one restricting portion 9e due to, for example, the eccentricity of the drive pulley 8 or the deformation of the belt 11. Then, the guide member 9 rotates following the rotation of the guide member 9, and the contact state between the belt 11 and the two regulating portions 9e is always kept good. Further, FIG.
As shown in FIG. 4, a gap is maintained between the winding portion of the belt 11 meshing with the driving pulley 8 and the inner surface of the guide member 9 to keep them in a non-contact state. It is set smaller (a <b) than the tooth size b of the 11 tooth portions 11a.

[0015] As shown in FIG.
The receiving plate 17 has an elongated hole 17a extending in the direction of the support plate 18, and the second receiving plate 16 has an elongated engaging hole 16a.
a is formed so as to face the long hole 17a. On the other hand, a gear portion 10a is formed on an outer peripheral surface of the driven pulley 10, and a support shaft 20 having a concave groove 20a on an upper peripheral surface is inserted into a shaft hole 10b of the driven pulley 10. As shown in FIG. 7, the support shaft 20 is inserted into the long hole 17a so that the concave groove 20a sandwiches the first receiving plate 17, and a portion projecting below the driven pulley 10 is engaged. The driven pulley 10 is rotatably supported by the support shaft 20 until it comes into contact with the back of the hole 16a. At this time, the belt 11 is wound around the driven pulley 10 in advance as a force for sliding the support shaft 20 to the inner side of the long hole 17a and the engagement hole 16a, and if the tension of the belt 11 is used, the support shaft 20 is moved to the frame. 6 can be easily locked.

As shown in FIG. 8, the movable body 14 is composed of a metal lever 21 and a slider receiver 22 made of synthetic resin.
2 is joined and integrated. As shown in FIG. 9, the lever 21 has a knob 21a, a guide hole 21b through which the blind plate 4 is inserted, a cylindrical portion 21c inserted into the guide shaft 12, and a cylindrical portion 21c.
A hanging piece 21d hanging down from c is formed, and a sliding cylinder 23 made of synthetic resin is snapped into both ends of the cylindrical portion 21c. An L-shaped bent portion 21e, a guide protrusion 21f, and a support protrusion 21 are provided on the front surface of the hanging piece 21d.
g is formed, and a locking claw 21h and a stopper step 21i are formed on the back surface of the hanging piece 21d, and the first slider piece 24 is press-fitted into the support projection 21g.

As shown in FIGS. 10 and 11, the slider receiver 22 has a frame portion 22b having a storage hole 22a therein.
A projecting piece 22c extending upward from the frame portion 22b;
An annular portion 22d inserted into the guide shaft 13 is formed, and a stepped locking groove 22e is formed on the inner wall of the frame portion 22b. An uneven portion 22f having the same shape as the teeth 11a of the belt 11 is formed at the upper end of the protruding piece 22c, and a guide groove 22g is formed on the back surface of the protruding piece 22c. Further, the frame 22
A plurality of bosses 22h are formed on the front surface of b, and the first slider piece 24 and the second and third slider pieces 25 and 26 are caulked and fixed to these bosses 22h.

The movable member 14 constructed as described above is fixed to the belt 11 as described above. In this case, first, as shown in FIGS. Of the slider holder 2
The second protruding piece 22c is moved upward. At that time, lever 2
The one support protrusion 21g abuts one side surface of the protruding piece 22c, and the guide protrusion 21f is engaged with the guide groove 22g. The support protrusion 21g and the guide protrusion 21f allow the protruding piece 22c to be smoothly moved relative to the lever 21. Can be moved to Then, at the position where the upper end of the projecting piece 22c slightly enters the inside of the bent portion 21e, the upper end of the locking groove 22e abuts on the lower end of the stopper step 21i, and the force required to move the projecting piece 22c is reduced. In order to increase, the projecting piece 22
The movement of c is temporarily stopped. In this state, the belt 11 is hung on the upper end of the protruding piece 22c, and the teeth 11a of the belt 11 mesh with the uneven portions 22f of the protruding piece 22c. Thereafter, when the protruding piece 22c is further moved upward, as shown in FIGS. 14 and 15, the upper end of the protruding piece 22c completely enters the inside of the bent portion 21e. It is clamped by the portion 21e. At the same time, the locking claw 21h gets over the step of the locking groove 22e and snaps in, so that the lever 21 and the slider receiver 22 are integrated.

Next, the process of assembling the motor-driven slide type variable resistor configured as described above will be described.

First, the motor 7 is mounted on the support plate 18 of the frame 6.
And a driving pulley 8 is attached to the rotating shaft 7a of the motor 7.
Press-fit and fix. Then, the shaft hole 10 of the driven pulley 10
b, the groove 20a of the support shaft 20 is inserted into the elongated hole 17a, and the lower end of the support shaft 20 is inserted into the engagement hole 16a with the belt 11 wound around the driven pulley 10. I do. Thereafter, when the belt 11 is wound around the driving pulley 8, the tension of the belt 11 causes the support shaft 20 to move into the elongated hole 17 a.
The driven pulley 10 is rotatably supported by the support shaft 20 locked in the elongated hole 17a and the engagement hole 16a. Next, the guide member 9 is attached to the drive pulley 8, and before and after this, the cylindrical portion 21c of the lever 21 is moved.
One guide shaft 12 is inserted into the sliding cylinder 23 snapped into the groove, and both ends of the guide shaft 12 are caulked and fixed to the groove 19 a of the frame 6. Next, the respective slider pieces 24, 25 and 26 are caulked and fixed to the slider receiver 22, and the projecting piece 22c of the slider receiver 22 is slightly inserted into the bent portion 21e of the lever 21. A part of the belt 11 is hung on the upper end of the protruding piece 22c, and the tooth portion 1 of the belt 11 is
1a is engaged with the uneven portion 22f of the protruding piece 22c. Thereafter, the protruding piece 22c is further moved upward, the belt 11 is sandwiched between the protruding piece 22c and the bent portion 21e, and the locking claw 21h is snapped into the step portion of the locking groove 22e so that the lever 21 and the lever 21 are engaged. The movable pair 14 is fixed to the belt 11 by integrating the slider receiver 22. Next, the first slider piece 24 is press-fitted into the support projection 21g, so that the first slider piece 2
4 and the lever 21 are electrically connected, and the other guide shaft 13 is inserted into the annular portion 22d of the slider receiver 22, and both ends of the guide shaft 13 are caulked and fixed to the groove 15b of the frame 6. And the motor drive unit 1 shown in FIG.

Next, the resistance board 5 is inserted between the positioning grooves 2a of the one cover 2 and the cover 2 is mounted on the cover 2 so that the positioning projections 15a of the frame 6 fit into the positioning holes 5a of the resistance board 5 respectively. Overlap the motor drive unit 1,
At the same time, the other cover 2 is overlaid on the opposite side of the motor drive unit 1 and both covers 2 are screwed. In this state, most of the components of the resistance board 5 and the motor drive unit 1 are accommodated in the covers 2, but the knob 21 a and the guide hole 21 b of the lever 21 protrude from the gap at the upper end of the covers 2. . Next, the blind plate 4 is inserted into the guide holes 21.
b to cover the gap between the upper ends of the two covers 2 and finally screw the holders 3 to the left and right sides of the two covers 2 to fix both ends of the blindfold plate 4 to the holders 3. The assembly of the driving slide type variable resistor is completed.

When the motor driven slide type variable resistor is disassembled in order to replace the resistor substrate 5, the reverse of the above-described assembling process may be performed. Since the positioning groove 2a and the positioning protrusion 15a of the frame 6 are positioned and held, the slide slides along the positioning groove 2a of the cover 2 without complicated work such as removing a caulking or loosening a screw. With this simple operation, the resistance substrate 5 can be taken out.

Next, the operation of the motor driven slide type variable resistor configured as described above will be described.

When the motor 7 rotates in either the forward or reverse direction according to an external signal, the driving pulley 8 rotates in accordance with the rotating direction, and the rotational force of the driving pulley 8 is applied to the gear portion 8a and the tooth portion 11a. Since the transmission is reliably transmitted to the belt 11 by the engagement, the belt 11 is driven by the driving pulley 8 and the driven pulley 1
It turns around zero. When the belt 11 rotates, the movable body 14 fixed to the belt 11 is
It reciprocates along arrows 2 and 13 in the direction of arrow P or Q in FIG. Each of the sliders 24 to 26 is held by the movable member 14. The resistor (not shown) on the resistor substrate 5 and the second and third slider members 2 are moved by the movement of the movable member 14.
Since the position of sliding contact with 5, 26 changes, a resistance value corresponding to the sliding position is output. At that time, when the movable body 14 moves to the ends of both the guide shafts 12 and 13, the movable body 14 and the belt 11 cannot move any more and stop.
When the motor 7 continues to rotate, the phase of the gear portion 8a of the rotating drive pulley 8 and the tooth portion 11a of the stopped belt 11 are shifted, so that the belt 11 is pushed outward by the drive pulley 8, It comes into contact with the inner wall of the guide member 9. Here, since the minimum gap dimension a between the belt 11 and the guide member 9 is set smaller than the toothed dimension b of the tooth portion 11a of the belt 11, when the belt 11 is pushed outward by the dimension a, the guide is extended. The member 9 stops the belt 11 from spreading. Therefore,
The gear portion 8a of the driving pulley 8 cannot get over the tooth portion 11a of the belt 11, and the rotation of the driving pulley 8 and the motor 7 is forcibly locked by the belt 11, so that the gear portion 8a
The abnormal noise caused by the engagement and disengagement between the tooth 11a and the tooth 11a does not occur.

On the other hand, the operator operates the knob 21 of the lever 21.
When a finger touches a, static electricity charged to the operator is output through the first slider piece 24 and a current collector (not shown) on the resistance substrate 5 slidingly contacting the first slider piece 24, and based on the output signal. As a result, the rotation of the motor 7 stops. Then, the operator operates the knob 2
When the movable body 14 is reciprocated in the direction of the arrow P or Q in FIG. 1 by pinching 1a, the belt 11 rotates together with the driving pulley 8 and the driven pulley 10, and the movement of the movable body 14 is performed in the same manner as when the motor is driven. Is output. At this time, the belt 11 is in contact with both regulating portions 9 e of the guide member 9, and the relative position between the belt 11 and the guide member 9 is slightly shifted depending on the moving direction of the movable body 14. Is absorbed by That is, the direction in which the movable body 14 approaches the drive pulley 8 (arrow P
Direction), a force in the compression direction acts on the belt 11 between the movable body 14 and the driving pulley 8, and conversely,
When the movable body 14 moves away from the driving pulley 8 (the direction of the arrow Q), a pulling force acts on the belt 11 between the movable body 14 and the driving pulley 8. Since the guide member 9 rotates following the belt 11, the belt 11 always comes into contact with both regulating portions 9e with good balance, and the rotation of the belt 11 is not hindered by the guide member 9.

[0026]

As described above, according to the present invention,
A guide member is disposed around the belt wound around the driving pulley, and a gap smaller than the toothed dimension of the tooth portion of the belt is formed between the guide member and the belt, so that the belt stops rotating. And the motor tries to rotate,
The gear part of the drive pulley cannot get over the teeth of the belt,
Generation of abnormal noise due to engagement and disengagement between the gear portion and the tooth portion can be prevented. Moreover, since the spread of the belt is regulated by the guide member, it is not necessary to increase the tension of the belt, and it is possible to prevent the operability at the time of manual operation from lowering.
In addition, if a regulating portion for pressing the belt against the drive pulley is provided in a part of the guide member, the teeth of the belt can be reliably engaged with the gear portion of the drive pulley. Furthermore, when the guide member is provided rotatably about an axis parallel to the rotation axis of the drive pulley, the guide member also rotates in accordance with the rotation of the belt. Can be prevented.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing the overall configuration of a motor-driven slide variable resistor according to one embodiment of the present invention.

FIG. 2 is a perspective view of a motor drive unit provided in the motor driven slide type variable resistor.

FIG. 3 is an exploded perspective view showing a support structure of a drive pulley provided in the motor drive unit.

FIG. 4 is an explanatory diagram showing a positional relationship between the driving pulley and a guide member.

FIG. 5 is a cross-sectional view showing an attached state of the guide member.

FIG. 6 is an exploded perspective view showing a support structure of a driven pulley provided in the motor drive unit of FIG. 2;

FIG. 7 is a sectional view showing an attached state of the driven pulley.

8 is an exploded perspective view of a movable body provided in the motor drive unit of FIG.

FIG. 9 is a side view of a lever provided on the movable body.

FIG. 10 is a plan view of a slider receiver provided on the movable body.

FIG. 11 is a rear view of the slider receiver.

FIG. 12 is a plan view showing a state in which the movable body of FIG. 8 is being attached to a belt.

FIG. 13 is a sectional view taken along the line AA of FIG.

FIG. 14 is a plan view showing a state where the movable body of FIG. 8 has been attached to a belt.

FIG. 15 is a sectional view taken along the line BB of FIG. 14;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor drive unit 5 Resistance board 6 Frame 7 Motor 7a Rotating shaft 8 Drive pulley 8a Gear part 8b Flange part 9 Guide member 9b First snap claw 9c Second snap claw 9e Restriction part 10 Follower pulley 10a Gear part 11 Belt 11a Tooth portion 12, 13 Guide shaft 14 Movable body 16 Second receiving plate 16a Engagement hole 17 First receiving plate 17a Long hole 18 Support plate 18a Through hole 18b Restriction hole 19 Standing piece 19b Lock hole 20 Support shaft 20a Recess Groove 21 Lever 21a Knob 21d Hanging piece 21e Bend 21f Guide protrusion 21h Locking claw 21i Stopper step 22 Slider receiver 22a Storage hole 22c Projection piece 22e Lock groove 22f Uneven part 22g Guide groove 24, 25, 26 Slider piece

Claims (3)

(57) [Claims] A drive pulley having a gear portion on an outer peripheral surface;
A motor for rotating and driving the driving pulley, a driven pulley opposed to the driving pulley at a predetermined interval, and a tensioned member between the driving pulley and the driven pulley, the inner peripheral surface meshing with the gear portion. A belt provided with a tooth portion, a movable body fixed to a part of the belt, a slider piece provided on the movable body, and a resistance substrate slidably contacting the slider piece; A motor-driven slide-type variable resistor in which a resistance value is adjusted by a change in a sliding contact position between the slider piece and the resistance substrate accompanying reciprocation of a movable body, wherein a guide member is provided around the drive pulley. Wherein a gap smaller than the toothed dimension of the tooth portion is formed between the guide member and the belt. 2. The motor driven slide type variable resistor according to claim 1, wherein a regulating portion for pressing the belt against the driving pulley is provided in a part of the guide member. 3. The motor driven slide type variable resistor according to claim 1, wherein the guide member is rotatably provided around an axis parallel to a rotation axis of the drive pulley.