Infrared indoor/outdoor thermometer system

• US 5,499,024 A
• Filed: 05/06/1994
• Issued: 03/12/1996
• Est. Priority Date: 05/06/1994
• Status: Expired due to Fees

• Current Assignee: Measurement Specialties Limited (TE Connectivity Limited)
• Original Assignee: Measurement Specialties Incorporated (TE Connectivity Limited)
• Inventors: Germanton, Damon, Petrucelli, Steven P.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): HILL, ANDREW M
• Application Number:
  US08/238,895
• Time in Patent Office: 676 Days
• Field of Search: 340/870.18, 340/870.17, 340/870.24, 340/870.28, 340/870.29
• US Class Current: 340/870.17
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G08C 2201/51 Remote controlling of devices based on replies, status thereof
• CPC Class Codes: G08C 23/04 using light waves, e.g. infrared

Abstract

An indoor/outdoor thermometer system employs a wireless infrared telemetry link. An outdoor unit capable of being mounted on or in proximity to a window is equipped with a processor and modulation means to enable measurement of outdoor temperature and conversion to modulated data pulses. The data pulses are coded to provide noise immunity. The data is transmitted in a free space infrared medium and detected by an indoor unit which displays the outdoor temperature. The indoor unit is mounted in a suitable convenient indoor location. Indoor temperature may also be measured and displayed. An internal timing data transmission feature is employed to drastically reduce power consumption, enabling long lasting lithium type batteries to be deployed as the power source.

Claims

1. A thermometer system comprising:

a first unit which is capable of being mounted in proximity to an exterior window surface, said first unit including;

temperature transducing means to provide a measurement of

a first temperature at a first location;

first conversion means coupled to said transducing means to convert said temperature measurement to binary coded data;

modulation means, coupled to said first conversion means, to modulate said binary coded data to provide modulated binary coded data; and

interval infrared transmission means, coupled to said modulation means to transmit binary coded infrared energy corresponding to said modulated binary coded pulses only at predetermined periodic time intervals, wherein said interval transmission at predetermined periodic time intervals reduces operating power consumption of said thermometer system and said binary coded data provides immunity from noise;

a second unit positioned at a second location, having an infrared detector, second conversion means coupled to said detector, and having display means coupled to said second conversion means, whereby said detector detects said transmitted binary coded infrared energy and provides detected data pulses indicative of said first temperature to said second conversion means, said second conversion means converts said detected data pulses to numerical data representative of said first temperature and provides said numerical data to said display means for displaying said first temperature.

2. The thermometer system according to claim 1 wherein said first unit is powered by a lithium type battery.

3. The thermometer system according to claim 1 wherein said second unit comprises measuring means to measure a second temperature at said second location, wherein said measuring means is coupled to said display means for displaying said second temperature.

4. The thermometer system according to claim 1 wherein said temperature transducing means includes a thermistor to sense said first temperature.

5. The thermometer system according to claim 1 wherein said predetermined periodic time intervals range from 4 to 20 minutes.

6. The thermometer system according to claim 1 wherein said first unit further comprises:

a thermistor;

a reference resistor;

a capacitor;

a control circuit;

switching means to switch between a circuit connection of said capacitor to said resistor and a circuit connection of said capacitor to said thermistor, said switching means being controlled by said control circuit;

an oscillation circuit incorporating said switching means, said oscillation circuit coupled to said counting means and said control circuit;

counting means coupled to said oscillation circuit and to said control circuit;

said counting means providing a first number of counts corresponding to a first number of pulses generated by said oscillation circuit when said capacitor is switched to connect to said resistor, and a second number of counts corresponding to a second number of pulses generated by said oscillation circuit when said capacitor is switched to connect to said thermistor;

whereby said control circuit provides output data corresponding to said first and second number of counts and said first temperature measurement consists of said output data.

7. The thermometer system according to claim 1 further including a test mode for telemetry alignment wherein pulse coded infrared data indicative of said first temperature is transmitted by said first unit to said second unit, said infrared data being transmitted periodically at preprogrammed time intervals, and wherein said second unit detects and decodes said infrared data and displays said first temperature when said second unit is favorably positioned with respect to said first unit and wherein said second unit displays an error message when said second unit is not favorably positioned with respect to said first unit.

8. The thermometer of claim 1 wherein said second conversion means comprises:

amplification means coupled to said detection means for amplifying said detected binary coded data pulses;

demodulation means coupled to said amplification means for demodulating said amplified binary coded data pulses to provide demodulated binary coded data;

processing means coupled to said demodulation means for converting said demodulated binary coded data to numerical data representative of said first temperature, wherein said processing means provides said numerical data to said display means.

9. The thermometer system according to claim 1 further comprising an infrared reflective surface, said reflective surface being disposed between said first and second units, whereby said binary coded infrared energy from said first unit reflects off of said reflective surface towards said second unit, and said second unit detects said reflected binary coded infrared energy and displays said first temperature.

10. The thermometer system according to claim 1 wherein said modulation means modulates said binary coded data in a pulse width modulation format such that each of said modulated binary coded data pulses is a binary one pulse or binary zero pulse, said binary one pulses being distinguished from said binary zero pulses by each of said binary one pulses being of a predetermined pulse duration longer or shorter than the pulse duration of each of said binary zero pulses.

11. The thermometer system according to claim 1 wherein said second unit comprises first interval timing means to disable power to said detection means, said amplification means and said demodulation means during periods where no data transmission takes place, thereby reducing power consumption of said second unit.

12. The thermometer system according to claim 11 wherein said second unit further comprises measuring means to measure a second temperature at a second location, wherein said measuring means is coupled to said display means, said display means displaying said second temperature;

and second interval timing means to disable power to said measuring means during periodic programmed second time intervals, thereby further reducing power consumption of said second unit.

13. The thermometer system according to claim 11 wherein said second unit further comprises an on/off switch wherein said first temperature is displayed only when said on/off switch is turned on, and wherein if said on/off switch is switched off, said second unit continues to detect and convert binary coded infrared data transmitted by said first unit during said predetermined periodic time intervals such that when said on/off switch is switched back on, said first temperature according to the most recent binary coded infrared data transmission is displayed.

14. A thermometer system comprising:

a first unit which is capable of being mounted in proximity to an exterior window surface, said first unit including;

temperature transducing means to provide a measurement of a first temperature at a first location;

first conversion means coupled to said transducing means to convert said temperature measurement to binary coded data, said first conversion means including an oscillation circuit means, a counting means, a control circuit means, and a processor means, said oscillation circuit means coupled to said control circuit means and said counting means, said control circuit means interconnecting said counting means and said processor means, wherein said processor means provides binary coded data indicative of said temperature measurement and corresponding to an output data provided by said control circuit means, said output data corresponding to a first number of counts and a second number of counts provided by said counting means in response to said temperature transducing means;

modulation means, coupled to said first conversion means, to modulate said coded data to provide modulated data; and

interval infrared transmission means, coupled to said modulation means to transmit binary coded infrared energy corresponding to said modulated binary coded pulses only at predetermined periodic time intervals, wherein said interval transmission at predetermined periodic time intervals reduces operating power consumption of said thermometer system and said binary coded data provides immunity from noise;

a second unit positioned at a second location, having an infrared detector, second conversion means coupled to said detector, and having display means coupled to said second conversion means, whereby said detector detects said transmitted binary coded infrared energy and provides detected data pulses indicative of said first temperature to said second conversion means, said second conversion means converts said detected data pulses to numerical data representative of said first temperature and provides said numerical data to said display means for displaying said first temperature.

15. The thermometer system according to claim 14 wherein said first unit comprises:

a thermistor;

a reference resistor;

a capacitor;

a control circuit;

switching means to switch between a circuit connection of said capacitor to said resistor and a circuit connection of said capacitor to said thermistor, said switching means being controlled by said control circuit;

an oscillation circuit incorporating said switching means, said oscillation circuit coupled to said counting means and said control circuit;

counting means coupled to said oscillation circuit and to said control circuit;

said counting means providing a first number of counts corresponding to a first number of pulses generated by said oscillation circuit when said capacitor is switched to connect to said resistor, and a second number of counts corresponding to a second number of pulses generated by said oscillation circuit when said capacitor is switched to connect to said thermistor;

whereby said control circuit provides output data corresponding to said first and second number of counts and said first temperature measurement consists of said output data.

16. The thermometer system according to claim 14 wherein said first unit is powered by a lithium type battery.

17. The thermometer system according to claim 14 wherein said temperature transducing means includes a thermistor to sense said first temperature.

18. The thermometer system according to claim 14 wherein said predetermined periodic time intervals range from 4 to 20 minutes.

19. The thermometer system according to claim 14 further comprising an infrared reflective surface, said reflective surface being disposed between said first and second units, whereby said binary coded infrared energy from said first unit reflects off of said reflective surface towards said second unit, and said second unit detects said reflected binary coded infrared energy and displays said first temperature.

20. A method of measuring a first temperature at a first location with a first unit and displaying said first temperature on a second display unit, comprising the steps of:

transducing said first temperature to an electronic signal;

converting said electronic signal to a first number of counts and a second number of counts in response to said first temperature;

providing output data corresponding to said first number of counts and a second number of counts;

comparing said output data to determine said first temperature;

providing said electronic coded data indicative of said output data and said first temperature;

modulating said coded data to provide modulated binary coded data pulses;

transmitting binary coded infrared data pulses corresponding to said modulated binary coded data pulses at predetermined programmed time intervals, wherein the transmission at predetermined programmed time intervals reduces operating power consumption of said first unit and said binary coded data pulses provide immunity from noise;

detecting said infrared binary coded data pulses at said second display unit;

converting said detected binary coded data pulses to numerical data representative of said first temperature; and

displaying said first temperature on said second display unit.