Instrumentation loop-powered backlit liquid crystal display
First Claim
Patent Images
1. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
- a current instrumentation loop for providing a current representative of a value to be measured;
means for measuring the current value to provide a digital signal to an LCD;
an LCD responsive to said means for measuring for displaying the measured value; and
a light emitting diode (LED) circuit including an LED disposed proximate to said LCD and interconnected with, and driven by the current of, said current instrumentation loop for backlighting said LCD.
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Abstract
A loop-powered, backlit liquid crystal display (LCD) responds to a current instrumentation loop for providing a current representative of the value to be measured and an LCD for displaying the measured value. A light-emitting diode (LED) circuit, which includes an LED disposed proximate to the LCD, is interconnected with, and driven by, the current of the current instrumentation loop for backlighting the LCD.
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Citations
18 Claims
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1. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
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a current instrumentation loop for providing a current representative of a value to be measured; means for measuring the current value to provide a digital signal to an LCD; an LCD responsive to said means for measuring for displaying the measured value; and a light emitting diode (LED) circuit including an LED disposed proximate to said LCD and interconnected with, and driven by the current of, said current instrumentation loop for backlighting said LCD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
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terminal means for receiving current representative of a value to be measured; means for measuring the current value to provide a digital signal to an LCD; an LCD responsive to said means for measuring for displaying the measured value; and a light-emitting diode (LED) circuit including an LED disposed proximate to said LCD and interconnected and driven by said current for backlighting said LCD. - View Dependent Claims (10, 11, 12, 13)
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14. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
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terminal means for receiving a current representative of a value to be measured; means for measuring the current value to provide a digital signal to an LCD; an LCD responsive to said means for measuring for displaying the measured value; a light emitting diode (LED) disposed proximate to said LCD and interconnected and driven by the current of said current instrumentation loop for back lighting said LCD; biasing means interconnected with said LED to form a bias circuit; and a current regulating amplifier interconnected with the bias circuit and operated by the biasing means to regulate the current through said LED. - View Dependent Claims (15)
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16. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
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terminal means for receiving a current representative of a value to be measured; means for measuring the current value to provide a digital signal to an LCD; an LCD responsive to said means for measuring for displaying the measured value; a light emitting diode (LED) disposed proximate to said LCD and interconnected and driven by current received by said terminal means for back lighting said LCD; biasing means interconnected with said LED to form a bias circuit; a current regulating amplifier connected to the bias circuit and operated by the biasing means to regulate the current through said LED; and a voltage inverter circuit connected to said bias circuit, said bias circuit having one end connected to the positive terminal of said voltage inverter and the other end connected to the negative terminal of said voltage inverter for providing the increased voltage used to drive said LEDs without increasing the voltage burden on the instrumentation loop.
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17. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
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terminal means for receiving a current representative of a value to be measured; means for measuring the current value to provide a digital signal to an LCD; an LCD responsive to said means for measuring for displaying the measured value; a first and second light emitting diode (LED) connected in series and disposed proximate to said LCD and interconnected and driven by current received by said terminal means for backlighting said LCD; biasing means interconnected with said LEDs to form a bias circuit; a current regulating amplifier connected to the bias circuit and operated by said biasing means to regulate the brightness of said LED; and a voltage inverter circuit connected to said bias circuit, said bias circuit having one end connected to the positive terminal of said voltage inverter and the other end connected to the negative terminal of said voltage inverter for providing the increased voltage used to drive said LEDs without increasing the voltage burden on the instrumentation loop.
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18. A loop-powered, backlit liquid crystal display (LCD) for displaying a measured value comprising:
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terminal means for receiving a current representative of a value to be measured; means for measuring the current value to provide a digital signal to an LCD; an LCD responsive to said means for measuring for displaying the measured value; a light emitting diode (LED) disposed proximate to said LCD and interconnected and driven by current received by said terminal means for backlighting said LCD; biasing means interconnected in series with said LED to form a bias circuit; a current regulating amplifier connected in parallel with the bias circuit and operated by said biasing means to regulate the brightness of said LED; a voltage inverter circuit connected in parallel with said bias circuit, said bias having one end connected to the positive terminal of said voltage inverter and the other end connected to the negative terminal of said voltage inverter for providing increased voltage used to drive said LED without increasing the voltage burden on the instrumentation loop; and said means for measuring connected in parallel with a resistor placed in series with said current regulating amplifier and said voltage inverter for sensing voltage developed across the resistor for driving the LCD display.
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Specification