JPH0124649Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a knob for electronic equipment that is fitted to a rotating shaft having serrations, such as a volume shaft.

As shown in Figure 1, variable resistor (volume) 1
The fitting hole of the knob 3 that fits into the rotating shaft 2 of the
When the rotating shaft 2 has, for example, 18 serrations, the same 18 serrations 4 are formed on the inner surface of the mating hole 5 as shown in FIG. 2, or three serrations are formed as shown in FIG. Either the serrations 4 can be provided separately at three locations on the circumference of the mating hole 5, or the serrations 4 can be provided only in a part of the mating hole 5 as shown in Fig. 4a, and the special serrations 4 can be provided in the remaining parts as shown in Fig. 4b. A C-shaped spring (made of steel) 6 is fitted to suppress the outer circumference of the rotating shaft 2.
There are formats such as With the structures shown in Figures 2 and 3, if there are no dimensional errors, a good fit can be obtained between the rotary shaft 2 and the knob 3, but there are usually differences due to processing methods (for example, the shaft 2 is machined or Differences in molding by die casting, etc.), differences by manufacturer,
Since the dimensional accuracy of the rotating shaft 2 changes due to differences between manufacturing lots, etc., the strength of the fit will change unless the mold for the knob 3 is corrected each time. Also, while the rotating shaft 2 is made of metal, the knob 3 is often made of synthetic resin or a different metal, so due to the difference in thermal expansion coefficients, the mating force weakens due to temperature changes, which can cause ceiling-mounted electronic In a device, knob 3 may fall under its own weight. In addition, in the structure shown in Figs. 4 and 5, the rotating shaft 2
The disadvantage is that the centers of the knob 3 and the center of the knob 3 do not match exactly.Also, C-shaped springs 6 and 7 are introduced to provide elastic force, which is convenient for absorbing dimensional errors, but these springs There are problems with the workability of assembling and the increase in the number of parts.

In all of FIGS. 2 to 4, the knob 3 is a single cylinder with a bottom, but there is also a case where the knob 3 is a cylinder with a double bottom as shown in FIG. That is, in FIG. 5, there is a notch 32a partially inside the outer member 31 of the knob 3.
A small-diameter cylindrical body 32 is provided concentrically, and a C-shaped steel spring 7 shown in FIG. The outer peripheral surface of the cylindrical body 32 is flat, but serrations 4 are uniformly formed on its inner surface. This knob 3 uses the elasticity of the cylindrical body 32 and the spring 7 that reinforces it to absorb dimensional errors while leaving the outer member 31 as a rigid body. However, the point of using the spring 7 is still This is unfavorable in terms of workability and number of parts.

The present invention provides a knob structure that strengthens the elasticity of the internal cylindrical body itself, reduces the number of parts, and is suitable for absorbing dimensional errors. That is, the knob for electronic devices of the present invention has a bottomed cylindrical outer member that includes:
A cylindrical body having an outer diameter smaller than the inner diameter of the outer member is provided concentrically, the base of the cylindrical body is fixed to the bottom of the outer member, and a cross section perpendicular to the central axis of the cylindrical body is , at least a part of its inner surface has a shape that fits closely with the serrations of the rotating shaft to be mated, and the outer surface has a similar shape to the inner surface so as to have elastic force, as shown in the drawings below. This will be explained in detail with reference to an example.

FIG. 6 is a diagram showing an embodiment of the present invention, in which a is a longitudinal cross-sectional view taken along a plane including the central axis, and b is a cross-sectional view taken along a plane orthogonal to the central axis. The knob 3 has a double structure and consists of a bottomed cylindrical outer member 31 and a cylindrical body 32 concentrically fixed inside the outer member 31. Since the outer diameter of the cylindrical body 32 is smaller than the inner diameter of the outer member 31, a gap 33 is created between them. A stepped portion 31a is formed on the bottom surface of the outer member 31, and a collar portion 32b at the bottom of the cylindrical body 32 engages with the stepped portion 31a, thereby preventing rotation of the cylindrical body 32. The cylindrical body 32 is formed by press-fitting the flange 32b into the outer member 31, by bonding the flange 32b and the bottom surface 31b of the outer member 31 with adhesive, or by screwing or superpositioning between the two. It is fixed by welding using a sonic welding method or the like. The outer member 31 is made of synthetic resin or metal, but the cylindrical member 32
is made of synthetic resin and exhibits elasticity even though it is cylindrical due to the structure shown below. That is, the cylindrical body 32 shown in FIG. 6b has 18 serrations 4 on the inner surface, but at the same time, the outer surface 32c is also formed in a similar shape to the inner surface. This makes the cylindrical body 32 look like origami and has a large elastic deformability.
When the rotating shaft 2 shown in FIG. 1 is press-fitted into the mating hole 5, the diameter of the cylindrical body 32 increases uniformly, and the rotating shaft 2 is tightened by the reaction. In this way, an inner cylindrical body is obtained in which a suitable elastic force is obtained and there is no need to form a notch 32a or use a spring 7 as shown in FIG.

FIG. 7 is a diagram showing another embodiment of the present invention in which the shape of the cylindrical body 32 is different, and is a cross-sectional view taken in a plane perpendicular to the central axis. (The vertical cross-sectional view in the plane including the central axis is the same as in Figure 6a). In this example, the cylindrical body 32
The outer circumferential surface of is similar in shape to the inner circumferential surface, but serrations 4 are formed on the inner surface in three locations with three peaks each, and the space between them is made to protrude outward, so that the serrations 4 are formed in three locations. A bulging portion 32d is formed. This bulging portion 32d is effective in increasing the elasticity of the cylindrical body 32, and the elastic force can be easily changed by adjusting its wall thickness (modifying the mold).

In addition, since the outer member 31 and the inner cylindrical body 32 are manufactured separately, a draft angle is provided in which the inner diameter 32f of the cylindrical body 32 on the side of the collar 32b is larger than the diameter of the opening surface 32e in FIG. 6a. As a result, the rotating shaft 2 is mainly subjected to a radial pressing force on the side of the opening surface 32e, so when the rotating shafts are fitted together, there is a sudden push from the middle like the knob in FIGS. 2 and 3. Inconveniences such as hardening can be avoided, and there is an advantage that the pushing force required at the initial and final stages of insertion is approximately the same.

As mentioned above, with the knob structure of the present invention, it is possible to provide appropriate elasticity to the part that engages with the rotating shaft with a simple structure with a small number of parts, so dimensional errors can occur due to various factors. It has the advantage of being able to fit in a good condition with a rotating shaft having serrations, such as a volume shaft.

[Brief explanation of the drawing]

Figures 1 to 5 are explanatory views showing various conventional knob structures, Figure 6 is a sectional view showing one embodiment of the present invention, and Figure 7 is a sectional view showing another embodiment of the present invention. . In the figure, 2 is a rotating shaft, 3 is a knob, 4 is a serration, 5 is a mating hole, 31 is an outer member, and 32 is a cylindrical body.

Claims (1)

[Scope of utility model registration request] A cylindrical body having an outer diameter smaller than the inner diameter of the outer member is provided concentrically inside a bottomed cylindrical outer member, and the base of the cylindrical body is fixed to the bottom of the outer member; At least a part of the inner surface of the cross section perpendicular to the central axis of the shaped body has a shape that tightly fits with the serrations of the rotating shaft to be fitted, and the outer surface has a shape similar to the inner surface so as to have elastic force. A knob for electronic devices characterized by being