System and method for filtering output in mass flow controllers and mass flow meters
First Claim
1. A method for filtering an indicated flow in a mass flow device wherein said indicated flow a function of actual gas flow, the method comprising:
- determining if said indicated flow is within an allowable deviation of a baseline;
if said indicated flow is within said allowable deviation of said baseline, outputting said indicated flow as a filtered indicated flow; and
if said indicated flow is not within said allowable deviation of said baseline, outputting a value within said allowable deviation of said baseline as said filtered indicated flow.
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Accused Products
Abstract
Embodiments of the present invention provide a method for filtering an indicated flow. One embodiment of the present invention can include the steps of (i) determining if the indicated flow is within an allowable deviation of a baseline, (ii) if the indicated flow is within the allowable deviation, outputting the indicated flow as the filtered indicated flow, and (iii) if the indicated flow is not within the allowable deviation, outputting a value that is within the predefined range as the filtered indicated flow. This embodiment of the present invention can also include determining if the indicated flow has exceed a buffer. If the indicated flow has not exceeded the buffer, one embodiment of the present invention can continue to output the value that is within the allowable deviation. If, however, the indicated flow has exceeded the buffer, a timer can be started. If the indicated flow does not return to within the allowable deviation before the timer reaches a clock limit, the embodiment of the present invention can output the indicated flow, which remains outside of the buffer, as the filtered indicated flow.
Another embodiment of the present invention can include the steps of (i) filtering the indicated flow to derive an intermediate filtered indicated flow, (ii) deriving a weighted first derivative of the intermediate filtered indicated flow, and (iii) outputting a filtered indicated flow comprising the sum of the intermediate filtered indicated flow and the weighted first derivative of the intermediate filtered indicated flow.
10 Citations
25 Claims
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1. A method for filtering an indicated flow in a mass flow device wherein said indicated flow a function of actual gas flow, the method comprising:
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determining if said indicated flow is within an allowable deviation of a baseline;
if said indicated flow is within said allowable deviation of said baseline, outputting said indicated flow as a filtered indicated flow; and
if said indicated flow is not within said allowable deviation of said baseline, outputting a value within said allowable deviation of said baseline as said filtered indicated flow. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for filtering an indicated flow in a mass flow controller comprising:
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(A) outputting said indicated flow as said filtered indicated flow for a delay period;
(B) when it is determined that said indicated flow reaches an approximately steady state, outputting said indicated flow as said filtered indicated flow;
(C) determining if said indicated flow has remained within an allowable deviation from a baseline;
(D) if said indicated flow has remained within said allowable deviation, continuing to output said indicated flow as said filtered indicated flow; and
(E) if said indicated flow has not remained within said allowable deviation;
(1) outputting a value from within said allowable deviation as said filtered indicated flow;
(2) determining if said indicated flow has exceeded a buffer;
(3) if said indicated flow has exceeded said buffer;
a) engaging a timer having a clock limit;
b) determining if said indicated flow has returned to within said buffer prior to said timer reaching said clock limit; and
c) if said indicated flow has not returned to being within said buffer prior to said timer reaching said clock limit, outputting said indicated flow as said filtered indicated flow; and
d) if said indicated flow has returned to being within said buffer prior to said timer reaching said clock limit;
i) outputting said indicated flow as said filtered indicated flow if said indicated flow is within said allowable deviation; and
ii) continuing to output said value from within said allowable deviation as said filtered indicated flow if said indicated flow is not within said allowable deviation but is within said buffer. - View Dependent Claims (9, 10, 11, 13, 14, 15, 17, 18, 19, 20, 21)
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12. A method for filtering an indicated flow in a mass flow meter comprising:
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filtering said indicated flow to derive an intermediate filtered indicated flow;
deriving a weighted first derivative of said intermediate filtered indicated flow; and
summing said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow to derive a filtered indicated flow.
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16. A mass flow controller operable to:
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determine if an indicated flow is within an allowable deviation of a baseline;
if said indicated flow is within said allowable deviation, output said indicated flow as a filtered indicated flow; and
if said indicated flow is not within said allowable deviation, output a value that is within said allowable deviation as said filtered indicated flow.
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22. A system for filtering an indicated flow comprising a mass flow meter operable to:
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filter an indicated flow to derive an intermediate filtered indicated flow;
derive a weighted first derivative of said filtered indicated flow; and
derive an indicated flow from said sum of said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow. - View Dependent Claims (23, 24, 25)
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Specification