JPS6025848Y2 - rotary variable resistor - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement in the rotational operation of a rotary variable resistor that does not use a bearing fitting.

In a conventional rotary variable resistor, as shown in FIG. 1, an operating shaft is rotatably fitted into a through hole of a bearing fitting 39 fixed to a cover with a mounting screw cut into the outer periphery. A slider is fixed through an insulator on the insulating substrate, the slider is brought into sliding contact with a resistor and a current collecting conductor arranged on an insulating substrate, and terminals are connected to both ends of the resistor by rotation of an operating shaft. The structure was such that the resistance value between the terminal and the terminal connected to the current collecting conductor was changed.

In this method, a lubricant such as grease can be used between the bearing fitting 39 and the operating shaft, so smooth rotation can be obtained, but since the bearing fitting is used, it is expensive.

Therefore, for the purpose of cost reduction, as illustrated in Figs. 2 and 4, an insulating material with a hole in the bottom of the cover 26 and a resistor and a current collecting conductor arranged on the surface without using a bearing fitting is used. A slider holder 16', which is formed integrally with the waist operating shaft and which fixes the slider, is insulated from the bottom surface of the cover. A mounting bracket 32 for attaching the variable resistor to a printed circuit board, etc. is attached to the back surface of the insulating board by means of a cover 26. A method was devised to fix it.

Although this method has made it possible to reduce costs, axial play tends to occur in the operating shaft, and it is difficult to use lubricants such as grease.

On the other hand, recently, in order to prevent dust from entering the rotating sliding contact area, efforts have been made to bring the periphery of the slider holder closer to the insulating substrate, but this is done in the axial direction as shown in Figure 3. When rotating the operating shaft through the knob by applying a force at right angles to
The surface of the insulating substrate, the terminal lead-out portion of the resistor, and the slider holder come into contact with each other, resulting in increased friction, making rotation smooth and difficult, and furthermore, there is a drawback that the resistor is worn out.

The present invention is intended to improve these drawbacks, and an embodiment thereof will be described below with reference to FIGS. 5 and 6.

Reference numeral 1 denotes a substantially horseshoe-shaped insulating substrate, on the surface of which a horseshoe-shaped resistor 2 and a substantially ring-shaped current collecting conductor 3 are arranged concentrically.

Resistor terminals 4, 4' and a current collector terminal 5 are connected and fixed to both ends of the resistor 2 and the current collecting conductor 3, respectively.

Further, a hole 60 is bored in the center of the arcuate portion of the insulating substrate 1, and a plurality of notches 7 are provided around the periphery to engage with legs 29 of a cover 26, which will be described later.
is provided.

Reference numeral 8 denotes a ring-shaped anti-friction coating, which is composed of a synthetic resin coating such as epoxide resin or phenol resin containing tetrafluoroethylene powder with a size of about 1 to 10 μm, and its inner diameter is the same as the arc portion of the resistor 2. The outer diameter is approximately equal to or slightly larger than the outer diameter of the sliding locus of the protrusion 22 of the slider holder 16, which will be described later.

Reference numeral 9 denotes a slider made of elastic metal, which extends from the base 10 and has a pair of arm parts 11, 1 divided into a plurality of parts and urged downward.
1', and 12.12' are provided, one arm part 11,
11' has a plurality of contacts 13 and 13' that make sliding contact with the resistor 2.
The other arm portions 12 and 12' have contact points 14 and 14', which come into sliding contact with the current collecting conductor 3, projecting downward.

The slider 9 is fixedly attached to a recess 24 of a slider holder 16, which will be described later, through a pair of holes 15 and 15' provided in the base 10.

Reference numeral 16 denotes a nearly disc-shaped slider holder made of an insulating material such as elastic plastic and formed in multiple stages, and its base 17
An operating shaft 18 extends upward and a thin shaft 19 extends downward from the center of the base 17, and a ring-shaped protrusion 20 is provided on the top surface of the base 17 and comes into contact with a bottom surface 27 of a cover 26, which will be described later. ing.

A ring-shaped large diameter portion 21 is formed on the lower side of the base 17,
A plurality of smooth arc-shaped protrusions 22 are provided on the lower surface of the large diameter portion to protrude downward, and the height from the lower surface of the protrusions to the upper surface of the ring-shaped protrusion 20 is equal to the contact with the insulating substrate 1 of the cover 26. It is formed to be larger than the depth from the contact surface to the bottom surface 25, and the base 1
A plurality of arc-shaped grooves 23 are provided in the stepped portion between 7 and the large diameter portion 21.
The base portion 17 and the protrusion 22 provided on the large diameter portion 21 are elastically connected.

A recess 24 is formed on the back surface of the slider holder 16, and a pair of protrusions (not shown) provided on the bottom surface of the recess 24 are engaged with the holes 15 and 15' of the slider 9 and crushed. The slider 9 is fixed to a slider holder 16.

Further, a rotation stopper 25 rises upward from the outer periphery of the base portion 17, and engages with a stopper 30 of a cover 26, which will be described later, to restrict the rotation range of the operating shaft 18.

Reference numeral 26 denotes a cap-shaped cover made of metal. A center hole 28 is bored in the bottom surface 27 and rotatably fits on the operating shaft 18. A plurality of legs 29 hang down from the periphery, and a stopper 30 is provided on the outer periphery. is recessed and contacts the insulating substrate 1 at the open end edge 31.

Reference numeral 32 denotes a mounting bracket, and the flat plate portion 33 of the mounting bracket has the cover 26 attached thereto.
A plurality of square holes 34 are formed to engage with the legs 29 of the flat plate part 33, and both sides of the flat plate part 33 are bent at right angles to form side parts 35 and 35', in which the terminals 4 and 5 are respectively attached. Contact parts 37, 37' for mounting to the printed circuit board 36 in parallel are provided to protrude outward from the lower end of the insulating board 1, and the contact parts 37, 37'
A snap-in mounting leg 38.degree. 38' is provided approximately in the center of each.

The insulating substrate 1 is superimposed on the mounting bracket 32, and the thin shaft 19 of the slider holder 16 with the slider 9 attached is inserted into the hole 66 of the insulating substrate 1 and the corresponding hole in the mounting bracket. The operating shaft 18 passes through the center hole 28 of the cover 26.

The legs 29 of the cover 26 are engaged with the notches 7 of the insulating board 1, inserted into the square holes 34 of the mounting bracket 32, and then bent, thereby assembling and fixing the insulating board 1, the mounting bracket 32, and the cover 26. contacts 13, 13' and 14. of the slider 9.
14' are in pressure contact with the resistor 2 and current collecting conductor 3, respectively, and the protrusion 22 of the large diameter portion 21 of the slider holder 16 is in pressure contact with the anti-friction coating 8.

Since the present invention is constructed as described above, the slider holder 16 has a protrusion 22 provided on its large diameter portion 21 which is elastically coated with an anti-friction coating provided in a ring shape around the outer periphery of the resistor 2. The cover 26 is held between the bottom surface 27 of the cover 26 and the insulating substrate 1 while being in pressure contact with the cover 8 .

Therefore, there is no vertical play on the operating shaft 18, and since the anti-friction coating 8 contains tetrafluoroethylene powder with a small coefficient of friction, the friction between the protrusion 22 of the slider holder 16 and the anti-friction coating 8 is reduced. Friction is small, and furthermore, a groove 23 is bored in the step between the large diameter portion 21 and the base 17, and the protrusion 22 provided on the large diameter portion 21 and the base 17 are elastically connected, so that the operating shaft can be easily operated. As shown in FIG. 7, the rotational torque of No. 18 is about 1/4 of that in the case where the coating containing the anti-friction powder is not provided on the insulating substrate, and there is little variation.

FIG. 7 is a graph showing the torque corresponding to the rotation angle when a torque measuring device is attached to the shaft and the shaft is rotated at a constant angular velocity.

Therefore, as shown in FIG. 3, even when a force is applied to one side of the operating shaft in a direction perpendicular to the operating shaft, the shaft can be rotated smoothly and easily.

Furthermore, since the present invention does not use bearing fittings, the number of assembly steps is small, the cost is low, it is suitable for mass production, and the product can be provided at low cost.

[Brief explanation of drawings]

Figure 1 is a side view of a conventional rotary variable resistor with a bearing fitting.
Figure 2 is a perspective view of a rotary variable resistor that does not use a bearing bracket, Figure 3 is an example of how a rotary variable resistor is used, and Figure 4 is a diagram of a conventional rotary variable resistor that does not use a bearing bracket. 5 is a sectional view of an embodiment of the present invention, FIG. 6 is an exploded perspective view of the same, and FIG. 7 is a diagram showing the operating shaft rotation torque of a rotary variable resistor that does not use a bearing fitting. , A is the rotational torque of the product of the present invention, and ``A'' is the rotational torque when the conventional anti-friction film is not used. 1...Insulating substrate, 2...Resistor, 3.
・Open channel conductor, 4, 4'...Resistance terminal, 5...
...Collection terminal, 6...hole, 7...
Notch, 8... Anti-friction film, 9, curved slider, 1
0...Slider base, 11, 11'...
Slider arm, 12, 12'... Slider arm, 1
3.13'...Slider contact, 14,14'...
Curved slider contact, 15.15'... Slider hole, 1
6... Slider holder, 17... Slider base, 18... Operating shaft, 19... Thin shaft, 20... ...Ring-shaped protrusion, 21...Large diameter portion, 22...Protrusion, 23...Groove, 2
4... Concavity, 25... Rotation stopper, 26
...Cover, 27...Bottom, 28...
... Center hole, 29 ... Spread leg, 3゜ ... Stopper, 31 ... Board contact edge, 32 ...
・Mounting bracket, 33...Flat plate part, 34...
・Square hole, 35... Side part, 36... Printed circuit board, 37, 37'... Printed board contact part, 38... Snap-in mounting Legs, 39...
...bearing metal fittings.

Claims (1)

[Scope of utility model registration request] a cover, an insulating substrate on which a resistor and a current collecting conductor are arranged;
A rotary variable resistor in which a slider that comes into sliding contact with the resistor and the current collector is rotatably supported by a slider holder in a space formed by the cover and the insulating substrate, the slider holder comprising: The upper surface of the base is provided with an operating shaft that passes through a hole drilled in the cover, and a ring-shaped protrusion that contacts the lower surface of the cover.A slider is fixed to the lower surface of the base, and an arc-shaped thin concentric part is provided on the lower surface of the base. A ring-shaped large diameter part that is elastically held through a groove is arranged in a row, and a plurality of smooth circular arc protrusions are protruded from the lower surface of the large diameter part. Epoxide containing tetrafluoroethylene powder with a waist of 1 to 10 μm A rotary variable resistor in which an anti-friction coating made of resin or phenolic resin is disposed on the outer periphery of the resistor, and the anti-friction coating and the arcuate protrusion are in contact with each other.