Adaptive keypad
First Claim
1. An adaptive key pad apparatus having at least one key, comprising:
- a pressure transducer apparatus for each key defining a pressure responsive sensor, each sensor generating a parameter which varies in response to an amount of pressure applied to the sensor;
a measurement device coupled for obtaining an initial measure of the parameter for each sensor and thereafter intermittently obtaining a subsequent measure of the parameter for each sensor;
a memory for storing the initial parameter for each sensor;
a comparing device coupled to the measurement device and to the memory for generating a comparison value for each sensor in response to a comparison of each subsequent parameter measure of that sensor with the initial parameter measure of that sensor and generating an depressed key indication when the comparison value for that sensor meets a first predefined criteria; and
an adaptive device coupled to the memory and to the measurement device for modifying the initial parameter stored in the memory for each sensor when the subsequent parameter measure for that sensor satisfies a second predefined criteria.
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Accused Products
Abstract
An adaptive keypad which has one or more keys includes, for each key, a pressure transducer positioned below a semi-rigid faceplate where the pressure transducer has a resistance which decreases as the pressure compressing the transducer increases. The transducer is connected in series with a capacitor to define an RC circuit for each key. Each RC circuit has a charge time proportional to the pressure applied to the key. A time capture circuit initially and thereafter intermittently, obtains the charge time for each RC circuit for each key and computes a conductance value from that time. The initial conductance value is stored in a memory. A comparing circuit intermittently compares the initial conductance value with each subsequent conductance value generated for a key. If the comparison value generated is greater than a predefined amount, a signal is generated indicating that a key has been depressed. If the comparison value is greater than a predefined amount over a selected period of time indicating a key is permanently depressed, the initial conductance stored in the memory for that key will be modified to a new value against which subsequent comparisons will be made to determine if a key is depressed.
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Citations
18 Claims
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1. An adaptive key pad apparatus having at least one key, comprising:
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a pressure transducer apparatus for each key defining a pressure responsive sensor, each sensor generating a parameter which varies in response to an amount of pressure applied to the sensor; a measurement device coupled for obtaining an initial measure of the parameter for each sensor and thereafter intermittently obtaining a subsequent measure of the parameter for each sensor; a memory for storing the initial parameter for each sensor; a comparing device coupled to the measurement device and to the memory for generating a comparison value for each sensor in response to a comparison of each subsequent parameter measure of that sensor with the initial parameter measure of that sensor and generating an depressed key indication when the comparison value for that sensor meets a first predefined criteria; and an adaptive device coupled to the memory and to the measurement device for modifying the initial parameter stored in the memory for each sensor when the subsequent parameter measure for that sensor satisfies a second predefined criteria. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An adaptive keypad apparatus comprising:
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a key array comprising a plurality of key circuits, each key circuit comprising a sensor with a variable resistance characterized by a non-depressed steady state resistance, the sensor resistance being interconnected in series with a capacitor for defining an RC circuit with a charge time which varies in response to the resistance of the sensor; a time capture circuit interconnected to the plurality of key circuits for measuring the charge time of each circuit; an adaptive processor for receiving the charge time of each key circuit and processing that charge time according to a predefined criteria for generating an indication of when a key in the plurality of keys has been depressed and further generating a modification of the predefined criteria for any of the keys in response to a permanent alteration of the non-depressed steady state condition of that key.
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17. An adaptive keypad apparatus having at least one key comprising:
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a pressure sensor for each key; pressure measurement means interconnected to each pressure sensor for generating a initial measure of the pressure applied to each sensor and thereafter intermittently generating a subsequent measure of the pressure applied to each sensor; key depression indication means interconnected for comparing the initial pressure measure for each key with each subsequent pressure measure for that key to generate a first compare value and generating a depressed key indication if the compare value satisfies a first pre-defined criterion; and adaptive means interconnected for comparing the initial pressure measure for each key with each subsequent pressure measure for that key to generate a second compare indication and modifying the initial pressure measure for that key if the second compare indication meets a second predefined criteria.
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18. An method of modifying the sensitivity of individual keys on a keypad apparatus having at least one key and a pressure sensor associated with each key comprising the steps of:
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scanning each key of the keypad and measuring the pressure applied against each key on a first scan for generating a initial measure of the pressure applied to each sensor; intermittently scanning each key of the keypad and measuring the pressure applied against each key on each subsequent scan for generating a subsequent measure of the pressure applied to each sensor; comparing the initial pressure measure for each key with each subsequent pressure measure for that key to generate a first compare value; generating a depressed key indication if the first compare value satisfies a first predefined criteria; comparing the initial pressure measure for each key with each subsequent pressure measure for that key to generate a second compare value; and modifying the initial pressure measure for a key if the second compare value for that key satisfies a second predefined criteria.
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Specification