Apparatus and method for an automatic self-calibrating scale
First Claim
1. An automatic calibration system for an electronic instrument for measuring a parameter for producing an output signal which undesirably has to be calibrated as a function of ambient conditions, said automatic calibration system comprising:
- automatic means coupled to said electronic instrument for periodically turning on said electronic instrument independent of an applied load force; and
calibration means responsive to said ambient conditions for calibrating said electronic instrument according to said ambient conditions to enable a correct measurement to be made.
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Accused Products
Abstract
The present weight scale performs automated self calibration by periodically initiating a measurement operation to determine the zero offset from a true weight reading due the weight scale'"'"'s intrinsic weight. The weight scale'"'"'s intrinsic weight will vary due to changes in environmental conditions such as temperature and humidity, which impact the behavior of the internal electronics that perform the weight measurement operations. The automated self calibration is provided by a counter circuit, clocked by a low power oscillator, that periodically initiates the weight scale'"'"'s electronics to undertake a weight measurement of the tare weight value of the scale. The tare weight value is stored in memory until replaced by a subsequent tare weight value calculation. During a weight measurement operation the gross weight measurement is deducted by the tare weight value stored in memory to arrive at a net weight representing a user'"'"'s true weight.
76 Citations
29 Claims
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1. An automatic calibration system for an electronic instrument for measuring a parameter for producing an output signal which undesirably has to be calibrated as a function of ambient conditions, said automatic calibration system comprising:
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automatic means coupled to said electronic instrument for periodically turning on said electronic instrument independent of an applied load force; and calibration means responsive to said ambient conditions for calibrating said electronic instrument according to said ambient conditions to enable a correct measurement to be made. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An automatic calibration system for an electronic instrument for measuring a parameter for producing an output signal which undesirably has to be calibrated as a function of ambient conditions, said automatic calibration system comprising:
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automatic means coupled to said electronic instrument for periodically turning on said electronic instrument comprising a 20 bit digital counter operable for setting the period at approximately every twenty minutes at which said instrument is turned on; and calibration means responsive to said ambient conditions for calibrating said electronic instrument according to said ambient conditions to enable a correct measurement to be made. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An electronic weight scale operable for automated self calibration comprising:
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a timing circuit operable to periodically trigger said electronic weight scale to initiate a weight measurement upon the elapse of a predetermined interval of time, wherein said timing circuit comprises an oscillating circuit and a 20 bit digital counter circuit driven by said oscillating circuit, said 20 bit digital counter circuit operable to provide an output signal; a measurement circuit operable to determine a tare weight value for said electronic scale in response to said output signal provided by said timing circuit; and a storage device coupled to said measurement device, wherein said storage device is operable to store the most updated said tare weight value for retrieval by said measurement circuit to subtract from a subsequent weight measurement for a load applied to said electronic scale. - View Dependent Claims (15, 16, 19, 20, 21, 22)
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- 17. The electronic scale in accordance 14, wherein said measurement circuit is operable to disregard said tare weight value which is out of range of a predetermined criterion.
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23. A method for automatically calibrating the zero shift in an electronic weight scale due to changes in tare weight value influenced by changing environmental conditions, said method comprising the steps of:
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determining an elapse of a predetermined period of time of approximately twenty minutes; measuring said tare weight value of said electronic weight scale upon said elapse of said predetermined period of time; storing said tare weight value for subtraction from subsequent weight measurements when a load is applied to said electronic weight scale; and repeating, after an said elapse of said predetermined period of time, said steps of determining, measuring, and storing after each prior sequence of said steps of determining, measuring, and storing. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification