Detented optical encoder

• US 6,353,429 B1
• Filed: 11/30/1999
• Issued: 03/05/2002
• Est. Priority Date: 11/30/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Long, Clare
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Nguyen, Jimmy H.
• Application Number:
  US09/451,476
• Time in Patent Office: 826 Days
• Field of Search: 345/158, 345/163, 345/164, 345/165, 345/166, 345/167
• US Class Current: 345/158
• CPC Class Codes: G01D 5/34738 Axles; Driving or coupling means
• CPC Class Codes: G06F 3/0312 for tracking the rotation of a spherical or circular member, e.g. optical rotary encoders used in mice or trackballs using a tracking ball or in mouse scroll wheels tracking relative movement in co-operation with a regularly or irregularly patterned surface, e.g. as in optical mice G06F3/0317; constructional details of scroll or thumb-wheels G06F3/0362; optical rotary encoders G01D5/3473
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/0362 with detection of 1D translations or rotations of an operating part of the device, e.g. scroll wheels, sliders, knobs, rollers or belts
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A detented encoder, employed for sensing a rotation of a wheel by a user between detent position, and suited for use in a pointing device or other user input device. The detented encoder includes a light emitter, a pair of photodetectors, and a codewheel. Interruption of light emitted by the light emitter and received by the photodetectors is processed by a logic circuit to produce a quadrature signal indicative of the detent position of the wheel. The codewheel is integral to a shaft that is supported at one end by a support bracket connected to the lower case of the device. The wheel rotates the shaft when turned by a user. The shaft includes a plurality of evenly-spaced, longitudinally extending spline teeth. A biasing member or opto spacer is operatively coupled to the lower case and includes a base portion on which the light emitter and photodetector are mounted. The biasing member includes a cantilever portion. A U-shaped slot in the cantilever portion includes a protrusion that engages the spline teeth on the shaft. The protrusion is biased against the splined portion of the shaft, so that as the shaft is rotated, the protrusion moves in and out of spline wells defined between adjacent spline teeth, thereby creating a detent action. The detented encoder also includes a microswitch that is activated by the shaft when a user depresses the wheel. A logic device processes the signal produced by the photodetector to determine the transitions between the detent positions as the wheel is turned.

Claims

1. A detented encoder employed for sensing a rotation of a wheel by a user, comprising:

(a) a rotatable shaft on which the wheel is mounted, said shaft having a splined portion that includes a plurality of evenly-spaced, longitudinally extending spline teeth defined about a surface thereof;

(b) a light source;

(c) a light sensor that produces a signal indicative of an intensity of light received from the light source;

(d) a support having a bearing surface in which the shaft is rotatably mounted;

(e) a biasing member, operatively coupled to the support and including;

(i) a base portion on which the light source and the light sensor are mounted; and

(ii) a cantilever portion connected to the base portion and applying a pre-load force against the splined portion of the shaft, said cantilever portion including a protrusion disposed adjacent to the splined portion of the shaft and engaging a spline tooth from among the plurality of spline teeth in the splined portion, the pre-load force provided by the cantilever portion being applied through the protrusion against the splined portion of the shaft such that when the shaft is rotated by the wheel, the cantilever portion flexes as the protrusion moves in and out of spline wells defined between adjacent spline teeth, thereby producing a detent action that defines a plurality of detent positions at equally-spaced angles of rotation corresponding to the plurality of equally-spaced spline teeth; and

(f) a codewheel mounted on the shaft and having a plurality of radially-extending, circumferentially spaced-apart teeth between which are defined slots, said teeth passing between the light source and the light sensor when the wheel is turned and rotates the shaft, which rotates the codewheel, said teeth interrupting the light received by the light sensor from the light source so that the signal produced by the light sensor is indicative of the rotation of the wheel.

2. The detented encoder of claim 1, wherein the cantilever portion comprises a pair of elastomeric arms extending from the base portion.

3. The detented encoder of claim 1, wherein the biasing member comprises a plastic.

4. A detented encoder employed for sensing a rotation of a wheel by a user, comprising:

(a) a rotatable shaft having a supported end and a free end, and a splined portion that includes a plurality of evenly-spaced, longitudinally extending spline teeth defined about a surface thereof, said wheel being mounted on the shaft;

(b) a supporting member;

(c) a light source;

(d) a light sensor that produces a signal indicative of an intensity of light received from the light source;

(e) a bracket connected to the supporting member and having a bearing surface defined therein in which the supported end of the shaft is rotatably mounted;

(f) a biasing member, operatively coupled to the supporting member and including;

(i) a base portion on which the light source and the light sensor are mounted; and

(ii) a cantilever portion connected to the base portion and applying a biasing force against the splined portion of the shaft, said cantilever portion comprising;

(1) a U-shaped opening adapted to receive the splined portion of the shaft; and

(2) a protrusion disposed generally in a center of the opening, to engage a spline tooth of the plurality of spline teeth in the splined portion of the shaft, the cantilever portion providing the biasing force through the protrusion as a pre-load against the splined portion of the shaft such that when the shaft is rotated by the wheel, the cantilever portion flexes as the protrusion moves in and out of spline wells defined between adjacent spline teeth, thereby producing a detent action that defines a plurality of detent positions at equally-spaced angles of rotation corresponding to the equally spaced-apart spline teeth; and

(g) a codewheel mounted on the shaft and having a plurality of radially-extending, circumferentially spaced-apart teeth between which are defined slots, said teeth passing between the light source and the light sensor when the wheel is turned, rotating the shaft, which rotates the codewheel, said teeth interrupting the light received by the light sensor from the light source so that the signal produced by the light sensor is indicative of the rotation of the wheel.

5. The detented encoder of claim 4, wherein the cantilever portion comprises a pair of elastomeric arms extending from the base portion.

6. The detented encoder of claim 4, wherein the biasing member comprises a plastic.

7. The detented encoder of claim 4, further comprising a slotted bracket connected to the supporting member and having defined therein a slot that receives the free end of the shaft, said slot controlling a lateral displacement of the free end of the shaft.

8. The detented encoder of claim 7, further comprising a switch disposed adjacent to the shaft, wherein the slot in the slotted bracket allows the shaft to be displaced so as to activate the switch upon application of a force on the wheel in a direction aligned with the slot in the slotted bracket.

9. The detented encoder of claim 4, wherein the supporting member includes a locating pin, and the base portion of the biasing member includes a location hole that receives the locating pin to control a disposition of the biasing member relative to the supporting member.

10. The detented encoder of claim 4, wherein the base portion of the biasing member defines a plurality of locating holes for mounting the light source and the light sensor, such that a disposition of the light source relative to the light sensor, and a disposition of the light source and the light sensor relative to the biasing member is controlled.

11. The detented encoder of claim 4, wherein the base portion of the biasing member includes a clip for retaining the light source.

12. The detented encoder of claim 4, wherein the base portion of the biasing member includes a clip for retaining the light sensor.

13. The detented encoder of claim 4, further comprising a printed circuit board mounted to the supporting member, wherein the biasing member includes at least one leg received in a respective hole in the printed circuit board to mount the biasing member onto the circuit board.

14. The detented encoder of claim 4, wherein the cantilever portion of the biasing member comprises a bearing surface disposed adjacent to the bracket, the bearing surface acting against the bracket when the cantilever portion is caused to flex by the detent action, to limit a movement of the cantilever portion in a direction substantially transverse to a longitudinal axis of the shaft.

15. The detented encoder of claim 4, wherein the light sensor comprises a pair of photodetectors that are spaced apart at a distance based on a width of the slots in the codewheel such that the light sensor produces a quadrature output when the wheel is turned.

16. The detented encoder of claim 15, wherein the light source comprises a light emitting diode and the photodetectors each comprise a phototransistor.

17. The detented encoder of claim 15, further comprising a logic device that processes the quadrature output to produce data indicative of a detent position when the wheel is turned.

18. A detented encoder employed in a pointing device, for sensing a detent position of a wheel when the wheel is turned by a user, comprising:

(a) a horizontally-disposed rotatable shaft having a supported end, a free end, and a splined portion that includes a plurality of evenly-spaced, longitudinally extending spline teeth defined about a surface thereof, said wheel being mounted on the shaft;

(b) a support member;

(c) a light source;

(d) a photodetection circuit comprising a pair of light sensors, each light sensor of said pair producing a signal indicative of an intensity of light received from the light source by that light sensor;

(e) a logic device coupled to the photodetection circuit;

(f) a bracket connected to the support member and having a bearing surface defined therein to rotatably mount the supported end of the shaft;

(g) a slotted bracket connecting to the support member and having defined therein a slot that receives the free end of the shaft, said slot controlling a lateral displacement of the free end of the shaft;

(h) a biasing member, operatively coupled to the support member and including;

(i) a base portion on which the light source and the light sensors are mounted; and

(ii) a cantilever portion connected to the base portion and applying a biasing force against the splined portion of the shaft, said cantilever portion comprising;

(1) a U-shaped opening adapted to receive the splined portion of the shaft; and

(2) a protrusion disposed generally in a center of said opening, to engage a spline tooth from among the plurality of spline teeth in the splined portion of the shaft, the cantilever portion being sufficiently elastomerically displaced to provide a vertical pre-load through the protrusion against the splined portion of the shaft such that when the shaft is rotated by the wheel, the cantilever portion flexes as the protrusion moves in and out of spline wells defined between adjacent spline teeth, thereby producing a detent action that defines a plurality of detent positions at equally-spaced angles of rotation; and

(i) a codewheel mounted on the shaft and having a plurality of radially-extending teeth between which are defined slots, said teeth passing between the light source and the light sensors as the rotation of the wheel rotates the shaft, which rotates the codewheel, said teeth interrupting the light received by the light sensors from the light source so that signals produced by the photodetection circuit and processed by the logic device to produce a quadrature signal are indicative of the detent position of the wheel when the wheel is turned by the user.

19. The detented encoder of claim 18, further comprising a switch disposed under the shaft, wherein the slot in the slotted bracket allows the shaft to be vertically displaced so as to activate the switch upon application of a downward force on the wheel by the user.

20. The detented encoder of claim 18, wherein the pointing device one of a mouse and a trackball.