Determining the distance an object has moved using an accelerometer
First Claim
1. A device comprising:
- an accelerometer that generates an acceleration signal having a magnitude;
an analog-to-digital converter (ADC), wherein the ADC converts the acceleration signal into a digitized acceleration signal; and
an object control unit that calculates a distance moved, wherein the object control unit receives the digitized acceleration signal, wherein the object control unit determines a first derivative of the digitized acceleration signal, wherein the first derivative is used to indicate a time period of an upward or downward movement of the device, and wherein the object control unit uses the first derivative of the digitized acceleration signal to start the calculation of the distance moved when the magnitude of the digitized acceleration signal is above a threshold.
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Accused Products
Abstract
An accelerometer-based mouse is one example of a device that determines the distance an object moves. The mouse disables a cursor from moving across a computer screen during movements of the mouse that occur while the mouse is lifted from a working surface. A mouse control unit generates a cursor movement disable signal that stops the cursor from moving from the time the mouse is lifted until the mouse is set down. The mouse control unit generates the disable signal by determining the derivative of an acceleration signal for the vertical (z) dimension relative to the working surface. The mouse includes a microcontroller programmed to disengage cursor movement when the cursor movement disable signal is asserted. The mouse does not include a ball and rollers whose performance can degrade as they become dirty. The mouse can detect movement even when the mouse slides over a surface that has no pattern.
48 Citations
30 Claims
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1. A device comprising:
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an accelerometer that generates an acceleration signal having a magnitude; an analog-to-digital converter (ADC), wherein the ADC converts the acceleration signal into a digitized acceleration signal; and an object control unit that calculates a distance moved, wherein the object control unit receives the digitized acceleration signal, wherein the object control unit determines a first derivative of the digitized acceleration signal, wherein the first derivative is used to indicate a time period of an upward or downward movement of the device, and wherein the object control unit uses the first derivative of the digitized acceleration signal to start the calculation of the distance moved when the magnitude of the digitized acceleration signal is above a threshold. - View Dependent Claims (2, 3, 4)
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5. A device comprising:
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an accelerometer that generates an x-acceleration signal and a z-acceleration signal, wherein the z-acceleration signal has a magnitude; an analog-to-digital converter (ADC), wherein the ADC converts the x-acceleration signal into a digitized x-acceleration signal and converts the z-acceleration signal into a digitized z-acceleration signal; and a control unit that calculates a magnitude of an x-distance, wherein the control unit receives the digitized x-acceleration signal and the digitized z-acceleration signal, wherein the control unit determines a first derivative of the digitized z-acceleration signal and uses the first derivative to indicate a time period during which the accelerometer moves in a z-dimension, and wherein the control unit uses the first derivative of the digitized z-acceleration signal to stop the magnitude of the x-distance from changing without stopping the accelerometer from generating the x-acceleration signal when the magnitude of the z-acceleration signal is above a threshold. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 26)
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16. A method comprising:
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(a) receiving an x-acceleration signal; (b) receiving a z-acceleration signal; (c) digitizing the z-acceleration signal to generate a digitized z-acceleration signal; (d) generating a first derivative of the digitized z-acceleration signal and using the first derivative to indicate a time period of movement in a z-dimension; and (e) generating a cursor movement disable signal using the first derivative of the digitized z-acceleration signal. - View Dependent Claims (17, 18, 19, 20, 21, 29)
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22. A device comprising:
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an accelerometer that generates an x-acceleration signal, a y-acceleration signal and a z-acceleration signal, wherein the x-acceleration signal and the y-acceleration signal are used to scroll a cursor across a screen when the accelerometer moves, and wherein the x-acceleration signal has a magnitude; and means for disabling the cursor by generating a first derivative of the z-acceleration signal and using the first derivative to indicate a first time period during which the accelerometer moves in a z-dimension, wherein the cursor is disabled from moving across the screen during a disabled period, and wherein the disabled period includes a second time period during which the magnitude of the x-acceleration signal is changing. - View Dependent Claims (23, 24, 25)
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27. A device comprising:
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an accelerometer that generates an x-acceleration signal and a z-acceleration signal, wherein the z-acceleration signal has a magnitude; an analog-to-digital converter (ADC), wherein the ADC converts the x-acceleration signal into a digitized x-acceleration signal and converts the z-acceleration signal into a digitized z-acceleration signal; and a control unit that calculates a magnitude of an x-distance, wherein the control unit receives the digitized x-acceleration signal and the digitized z-acceleration signal, wherein the control unit determines a first derivative of the digitized z-acceleration signal and uses the first derivative to indicate a time period during which the accelerometer moves in a z-dimension, wherein the control unit uses the first derivative of the digitized z-acceleration signal to stop the magnitude of the x-distance from changing without stopping the accelerometer from generating the x-acceleration signal when the magnitude of the z-acceleration signal is above a threshold, wherein the control unit uses the first derivative to generate a pseudo square wave, wherein the pseudo square wave includes noise with a highest peak, and wherein the pseudo square wave has a lowest notch whose magnitude is greater than that of the highest peak of the noise. - View Dependent Claims (28)
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30. A device comprising:
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an accelerometer that generates an x-acceleration signal, a y-acceleration signal and a z-acceleration signal, wherein the x-acceleration signal and the y-acceleration signal are used to scroll a cursor across a screen when the accelerometer moves, and wherein the x-acceleration signal has a magnitude; and means for disabling the cursor by generating a first derivative of the z-acceleration signal and using the first derivative to indicate a first time period during which the accelerometer moves in a z-dimension, wherein the cursor is disabled from moving across the screen during a disabled period, wherein the disabled period includes a second time period during which the magnitude of the x-acceleration signal is changing, wherein the means generates a second derivative of the z-acceleration signal and adds the second derivative to the first derivative to generate a pseudo square wave, wherein the pseudo square wave includes noise with a highest peak, and wherein the pseudo square wave has a lowest notch whose magnitude is greater than that of the highest peak of the noise.
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Specification