Predictive and pulsed illumination of a surface in a micro-texture navigation technique
First Claim
1. A method of exposing to light a surface having a micro-texture upon which an optical navigation circuit tracks movement, the method comprising the steps of:
- (a) illuminating the surface with pulses of light occurring at a selected rate;
(b) determining a velocity from the tracked movement;
(c) increasing the selected rate in response to increases in the determined velocity; and
(d) decreasing the selected rate in response to decreases in the determined velocity.
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Accused Products
Abstract
An optical navigation system saves power by pulsing its surface illumination light source to provide light only when needed. The level of light may be controlled by a servo-mechanism that monitors degree of correlation data and average illumination, and that changes the controlled level at times when it is both required and safe to do so. As for creating different levels of illumination, that maybe accomplished by: (1) pulsing the light on and then opening the electronic shutter for some period of time during the pulse (gating the light); (2) opening the shutter and then varying the pulse width of the light (gating the LED); (3) opening the shutter and then pulsing the LED at different intensities; and (4) a combination of(2) and (3). In addition, the velocity of the navigation circuit over the surface (or vise versa) can be determined, and in cases where it is safe to assume that limited acceleration is possible, at low velocities it is desirable to reduce the rate of data acquisition, and thereby pulse the light source less often and conserve power.
136 Citations
13 Claims
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1. A method of exposing to light a surface having a micro-texture upon which an optical navigation circuit tracks movement, the method comprising the steps of:
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(a) illuminating the surface with pulses of light occurring at a selected rate;
(b) determining a velocity from the tracked movement;
(c) increasing the selected rate in response to increases in the determined velocity; and
(d) decreasing the selected rate in response to decreases in the determined velocity. - View Dependent Claims (2, 3, 4)
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5. A method of sampling a surface having a micro-texture upon which an optical navigation circuit tracks movement, the method comprising the steps of:
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determining a velocity from the tracked movement;
determining a sampling rate of the surface based on the determined velocity; and
illuminating the surface with pulses of light at the determined sampling rate. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
(a) increasing the sampling rate based on increases in the determined velocity; and
(b) decreasing the sampling rate based on decreases in the determined velocity.
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11. A method as in claim 10, wherein steps (a) and (b) are computed increases and decreases, respectively.
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12. A method as in claim 10, wherein the respective increasing and decreasing of steps (a) and (b) comprise obtaining sample rate data from a table indexed by the determined velocity.
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13. A method as in claim 10, wherein illuminating nominally occurs at fixed periodic and minimal intervals and decreasing the sampling rate comprises suppressing a pulse of light in the nominally fixed periodic and minimal intervals.
Specification