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EXTERNALLY PROGRAMMABLE DETENT MECHANISM FOR NON-INTERNALLY DETENTED ROTARY POTENTIOMETERS

IP.com Disclosure Number: IPCOM000006102D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2001-Dec-04
Document File: 2 page(s) / 84K

Publishing Venue

Motorola

Related People

Larry Marvet: AUTHOR [+2]

Abstract

A mechanism is needed to provide a rotary switch easily changeable from a detented switch, i.e. 'stops' between positions, to a non-detented switch. This change must be possible after the radio housing is assembled and closed, and must be protected from adverse environments. Furthermore, the detents must be variable during assembly in the following characteristics: 1. detent force, 2. number of detent positions, 3. rotation angle between positions, and 4. total allowable rotation.

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MOTOROLA INC. Technical Developments Volume 12 April 1991

EXTERNALLY PROGRAMMABLE DETENT MECHANISM FOR NON-INTERNALLY DETENTED ROTARY POTENTIOMETERS

by Larry Marvet and Charles E. Kline

  A mechanism is needed to provide a rotary switch easily changeable from a detented switch, i.e. 'stops' between positions, to a non-detented switch. This change must be possible after the radio housing is assembled and closed, and must be protected from adverse environments. Furthermore, the detents must be variable during assembly in the following characteristics: 1. detent force, 2. number of detent positions, 3. rotation angle between positions, and 4. total allowable rotation.

  The mechanism consists of a detent washer (l), special washer (2), mating knob (3), two springs (4), and hvo ball bearings (5) as shown in the Figure. The detent washer has a keying mechanism that fixes it against rotating relative to the knob, in this instance a 'D'-shaped counterbore that fits over the 'D'-shaped mounting bushing of the radio's potentiometer (7). The special insert is placed over the detent washer and fixed to the potentiometer shaft (6) through a flexible ('snap') interference fit to the shaft. Thus, the special insert is attached to the rotating shaft and is over and adjacent to the non-rotating detent washer, thereby allowing relative motion between the special insert and the detent washer.

  The ball bearings and springs are inserted into the special insert, with the ball bearings rubbing against the detent washer; as the mating knob is pushed into place to captivate and cover the insert/spring/ball bearing assembly, the springs are pressed downward yielding a preload force on the ball bea...