Patent Application
20110061489
The present invention relates to rotary control knobs for automotive and consumer electronics applications, and more particularly to an improved rotary control knob apparatus that minimizes axial tilting of the knob.
Rotary knobs are commonly used in connection with automotive or consumer electronic products such as radios for user-adjustment of control parameters such as volume and tuning. A typical knob assembly comprises several mechanically coupled parts, and tolerance variations in the manufacture of the constituent parts can result in tolerance stack-up that allows the knob to axially tilt, or wobble, with respect to its mounting surface. Since this tilting or wobbling is aesthetically unpleasing, and can reflect unfavorably on the quality of the product, what is needed is a rotary control knob assembly in which the axial orientation of the knob is tightly controlled even though the parts of the assembly are subject to the usual manufacturing tolerance variations.
The present invention provides an improved rotary control knob apparatus including a stationary knob retainer having a cylindrical post and an annular knob that slides over the retainer post, where the exterior periphery of the retainer post has a distributed array of compliant protrusions that contact the inner periphery of the knob to provide a resilient sliding interference fit between the knob and the retainer post. In a preferred arrangement, the retainer is secured against the rear surface of a control panel trimplate, and the knob is axially captured between the trimplate and a retainer flange extending radially outward from the base of the cylindrical post.
Referring to the drawings, and particularly to
The circuit board 20 is fastened to the trimplate 12 so as to engage and axially capture the knob retainer 16 with respect to the trimplate 12. The circuit board 20 may additionally include lighting components (not shown) for backlighting graphics formed on the face 40 of push-button actuator 18, contacts (not shown) for interfacing with the push-button actuator 18, and a U-shaped optical sensor 42 with legs that straddle the toothed knob flange 34 to detect rotation of the knob 14. The circuit board 20 also includes an opening 44 for accommodating the circular well 38 of knob retainer 16.
As mentioned above, the principle objective of the present invention is to provide a rotary control knob assembly 10 in which the axial orientation of the knob 14 is tightly controlled even though the parts of the assembly 10 are subject to the usual manufacturing tolerance variations. This objective is achieved, according to this invention, by providing a resilient sliding interference fit between the knob 14 and the hollow cylindrical retainer post 22 on which the knob 14 is supported. In the illustrated embodiment, the interior periphery of the annular rotary knob 14 is smooth, and compliant features that provide the resilient sliding interference fit are formed on the exterior periphery of the hollow retainer post 22.
As best seen in
The exterior periphery of the retainer post 22 also includes a distributed array of non-compliant axial ribs 50 that extend radially outward from the wall of the post 22, but do not ordinarily engage the inner periphery of the knob 14. In the illustrated embodiment, some of the ribs 50 provide a complementary axial recess 52 on the inner periphery of the hollow retainer post 22; the recesses 52 accept complementary axial ribs 53 formed on the exterior periphery of push-button actuator 18 to properly orient and rotationally lock the push-button actuator 18 with respect to the retainer 16. For purposes of this invention, however, the axial ribs 50 on the exterior periphery of the retainer post 22 provide a hard stop to limit radially inward bending of the protrusions 46 in the event that lateral force applied to the grip portion 28 of knob 14.
Referring to
In summary, the rotary control knob apparatus 10 of the present invention provides a simple and cost-effective way of mounting and rotatably supporting an annular rotary control knob 14 such that the axial orientation of the knob 14 is tightly controlled even though the retainer 16 on which the knob 14 is mounted is subject to customary manufacturing tolerance variations. The distributed array of compliant protrusions 46 on the exterior periphery of the hollow retainer post 22 provide a resilient sliding interference fit between the retainer post 22 and the inner periphery of knob 14 to achieve a highly reliable and substantially tilt-free rotational mounting of the knob 14. Additional mounting rigidity is achieved by locking and securing the retainer 16 to the trimplate 12.
While the present invention has been described with respect to the illustrated embodiment, it is recognized that numerous modifications and variations in addition to those mentioned herein will occur to those skilled in the art. For example, the push-button actuator 18 may be omitted, rotation of the knob 14 may be sensed in a different manner than shown, the retainer 16 may be directly fastened to the trimplate 12, and so on. Also, it may be possible to form the compliant features 46 on the inner periphery of the knob 14 instead of on the exterior periphery of retainer post 22. Accordingly, it is intended that the invention not be limited to the disclosed embodiment, but that it have the full scope permitted by the language of the following claims.
