Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-08-13
2001-10-30
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S602000, C340S603000, C702S002000, C324S072000, C455S227000, C367S013000, C367S191000, C367S135000
Reexamination Certificate
active
06310554
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to weather sensors and a method of providing a warning of severe weather conditions. In particular, the invention relates to a battery operated severe weather detector which operates by sensing rapid rates of change in the atmospheric pressure and sounding a voice-enunciated alarm. The device is suitable for detecting and warning of approaching severe weather, including tornadoes, with sufficient timeliness and accuracy to allow the user to seek shelter before severe weather impacts.
It is commonly known in the art to use mechanical and electrical means to detect severe weather. However, these existing devices have not been able to significantly reduce the number of lives lost and amount of property damage associated with severe weather. Nationally tornadoes have killed between 15,000 and 20,000 people over the last century. Over the last decade, the average amount of property lost annually due to severe weather exceeded $1 billion nationally. While storms are monitored carefully by qualified meteorologists with sophisticated equipment and announced over radio and television, the rapid appearance of severe weather and limited access to such reports severely reduces the effectiveness of these weather detection and notification systems. As such, there exists a need for a reliable, self-contained and affordable severe weather detection device which is suitable for detecting and warning of impending severe weather.
SUMMARY OF THE INVENTION
Commonly known methods of detecting and warning of approaching severe weather are not sufficiently effective to decrease the financial and human casualties which often accompany severe weather conditions.
Known weather detection devices are not suitable for use in a portable, battery-powered device. The complicated components found in mechanical weather detection devices are too large and susceptible to physical changes over time to provide reliable warning information. Further, existing devices are susceptible to false alarms when seasonal fluctuations in the atmospheric pressure are interpreted as approaching severe weather. Existing weather detection devices also suffer from potential confusion with the alarms of other emergency detection devices. Finally, existing devices and systems for detecting severe weather are prohibitively expensive for widespread consumer use. The above disadvantages render the existing art inadequate. Exemplary devices are shown and described in U.S. Pat. Nos. 2,723,388; 3,594,753; 3,603,951; 3,631,435; 3,753,117; 4,170,132; 4,295,139; 4,602,248; 4,937,571; 5,105,191; 5,309,139; 5,402,116; and 5,612,667.
Accordingly, the present invention provides a severe weather detection apparatus and method of detecting and warning of approaching severe weather conditions. Barometric pressure is a relative value indicating the atmospheric pressure. The user is warned of changes in the barometric pressure which normally accompany the approach of severe weather. The barometric pressure of interest exists in a range from 26 to 32 inches of mercury. Storm activity, including tornadoes, are proceeded by a dramatic drop in the barometric pressure in this range.
The apparatus for detecting severe weather includes a micro-machined silicon pressure sensor and electronics for monitoring the barometric pressure. Such a sensor can be obtained at a low cost per unit and can be interchanged with a range of barometric pressure sensors. The micro-machined pressure transducer provides excellent linearity and low hysteresis. Piezoresistive strain gauges are machined onto a silicon diaphragm on the sensor in a Wheatstone bridge configuration using standardized techniques for manufacturing micro-electronic mechanical structures. A change in atmospheric pressure changes the impedance of the bridge, thereby producing a voltage output linear with atmospheric pressure. In an alternative embodiment, the bridge on the sensor can be laser trimmed to a specific barometric pressure range for better resolution. Unlike sensors used in existing mechanical barometric sensors, silicon is an elastic material which maintains its shape and functionality over years of continuous use. The durability of the silicon sensor also eliminates the need for periodic re-calibration.
The sensor output is coupled to a transducer measuring absolute pressure, which is coupled to a high performance operational amplifier. A 1.5 mA current is used to drive the transducer. Current input rather than voltage input improves the linearity of the sensor output when the sensor experiences temperature fluctuations in the environment. The amplified signal is then converted to a digital word by a digital-to-analog converter. An electronic digital memory chip stores the digital signal. The digital word is read into a microprocessor which monitors the signal from the sensor and computes a value based on the derivative of pressure data which reflects the rate of change of pressure. A sudden pressure drop is directly related to a large numerical value. Using this method, any barometric pressure drop is referenced to the pre-storm barometric pressure in the region thereby creating a floating threshold. A pre-recorded voice-enunciated alarm sounds based on a predetermined change in barometric pressure from the baseline threshold.
The Applicant's method and apparatus have numerous advantages over existing weather detection devices. First, the use of a ‘floating’ baseline threshold allows for the device to compensate for seasonal fluctuations in the barometric pressure which may otherwise cause missed or false alarms. Further, battery power allows the device to be easily installed in a wide range of applications. To extend battery power, all of the integrated circuits have low quiescent currents, enabling each digital integrated circuit to operate in a low-power mode during which power consumption is greatly minimized. Finally, the use of a voice-enunciated alarm allows the device to be easily distinguished from fire, security, radon, carbon monoxide or other alarms. Such a distinction must be made since people are conditioned to leave a building when most alarms go off, while the appropriate response to a severe weather alarm would be to take shelter within the building. The fact that the device is small, self-contained and powered by commercially available consumer batteries allows the device to be installed in a wide range of locations.
The invention also provides a method of detecting severe weather and a method of detecting and providing a voice enunciated warning of approaching severe weather conditions.
The Applicant's electronic microprocessor based solution to sensing severe weather provides the user with a reliable and low-cost method of protection and allows additional features to be added easily. For example, in an alternative embodiment, the severe weather detection apparatus could include a self-check feature to ensure the apparatus was functioning normally.
In an additional alternative embodiment, the severe weather detection apparatus could include display means for indicating the current barometric pressure and rate of change in the atmospheric pressure. Inclusion of such display means would assure the user that the device was functioning and allow curious users to manually monitor the barometric pressure.
In an additional alternative embodiment, the severe weather detection apparatus may include a port to allow the device to interface with a computer.
It is a principal advantage of the invention to provide a severe weather detection apparatus and method of detecting and warning of severe weather which provides the user with an accurate and timely warning of approaching weather.
It is another advantage of the invention to provide a severe weather detection apparatus that is suitable for stand-alone installation in a home or other suitable location.
It is another advantage of the invention to provide a severe weather detection apparatus that can be offered for sale at a price which will make the device available to a wide cr
Michael & Best & Friedrich LLP
Nguyen Tai T.
Wu Daniel J.
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