Temperature compensated electrobalance

Claim 2

An electrobalance device of the type having a beam pivotally mounted at a fulcrum, means for suspending a weight from the beam, means for detecting a displacement of the beam, which includes a source of heat, and a servosystem responsive to the detection means for applying a counterbalancing torque to the beam to reduce any beam displacement toward zero, comprising: a. a temperature detector associated with the beam for sensing whether or not the temperature at one end of the beam exceeds the temperature at the other end of the beam, and for producing an output signal representative of any such temperature difference; and b. a heat generator coupled to said temperature detector, and positioned adjacent saId other end of the beam, and further being operatively responsive to said signal from said temperature detector, thereby to elevate the temperature of said other end of the beam to the temperature of said one end so as to maintain the ends of the beam at substantially equal temperatures.

Claim 3

The electrobalance device of claim 1 further comprising: energy transfer means responsive to an input signal and coupled between said temperature detector and said heat generator for transferring energy to said heat generator in response to said signal from said temperature detector.

Claim 4

The electrobalance of claim 2 wherein said temperature detector includes: a bridge network having a first temperature sensor positioned to sense the temperature at said one end of the beam and forming one leg of said bridge network, and a second temperature sensor positioned to sense the temperature at said other end of the beam and forming another leg of said bridge network, said network being arranged to provide an output signal representative of the temperature difference between said ends of the beam.

Claim 5

The electrobalance of claim 3 wherein said bridge network is resistive in character.

Claim 6

The electrobalance of claim 4 wherein said first and second temperature sensors are thermistors.

Claim 7

The electrobalance of claim 2 wherein said energy transfer means includes: an operational amplifier having the signal input terminals coupled to said temperature detector for impressing said output signal on said amplifier, said amplifier further having power connections to which a voltage source may be connected, said amplifier being designed to supply varying amounts of current to said heat generator in response to said temperature detector output signal.

Claim 8

The electrobalance device of claim 6 wherein said heat generator includes an electrical heater element.

Claim 9

The electrobalance device of claim 7 further comprising: a blocking diode coupled between said operational amplifier and said heater element for permitting current to be directed only from said amplifier to said heater element when a temperature increase is indicated.

Claim 10

An electrobalance system comprising; a. a fulcrum; b. a beam pivotally mounted on said fulcrum; c. a beam displacement sensor juxtaposed one end of said beam, said sensor including a source of radiant heat and further being designed and adapted for producing an output displacement signal representative of said beam displacement; d. a servomechanism responsive to said output signal for applying a counterbalancing torque to said beam to maintain said beam at substantially zero displacement; e. a temperature detector associated with said beam for sensing whether or not the temperature at said one end of said beam exceeds the temperature at the other end of said beam, and for producing an output signal representative of any such temperature difference; and f. a heat generator coupled to said temperature detector, and positioned adjacent said other end of the beam, and further being operatively responsive to said signal from said temperature detector, thereby to elevate the temperature of said other end of the beam to the temperature of said one end so as to maintain the ends of the beam at substantially equal temperatures.

Claim 11

An electrobalance system comprising; a. a fulcrum; b. a beam pivotally mounted on said fulcrum; c. a beam displacement sensor juxtaposed one end of said beam, said sensor including a source of radiant heat and further being designed and adapted for producing an output displacement signal representative of said beam displacement; d. a servomechanism responsive to said output signal for applying a counterbalancing torque to said beam to maintain said beam at substantially zero displacement; e. a temperature detector associated with said beam for sensing whether or not the temperature at said one end of said beam exceeds the temperature at the other end of said beam, and for producing an output signal representative of any such temperature difference; and f. a heat generator coupled to said temperature detector, and positioned adjacent said other end of the beam, and further being operatively responsive to said signal from said temperature detector, thereby to elevate the temperature of said other end of the beam to the temperature of said one end so as to maintain the ends of the beam at substantially equal temperatures.

Claim 12

The electrobalance system of claim 9 further comprising: a buoyant body suspended from said beam whereby the buoyant forces on said body may be measured.

Claim 13

The electrobalance system of claim 10 further comprising: a vacuum tight enclosure for housing said system whereby the buoyant force of a gas on said buoyant body may be studied.

Claim 14

The electrobalance system of claim 11 wherein said temperature detector includes: a bridge network having a first temperature sensor positioned to sense the temperature at said one end of the beam and forming one leg of said bridge network, and a second temperature sensor positioned to sense the temperature at said other end of the beam and forming another leg of said bridge network, said network being arranged to provide an output signal representative of the temperature difference between said ends of the beam.

Claim 15

The electrobalance system of claim 12 wherein said bridge network is resistive in character.

Claim 16

The electrobalance device of claim 13 wherein said first and said second temperature sensors are thermistors.

Claim 17

The electrobalance system of claim 11 wherein said energy transfer means includes: an operational amplifier having the signal input terminals coupled to said temperature detector for impressing said output signal on said amplifier, said amplifier further having power connections to which a voltage source may be connected, said amplifier being designed to supply varying amounts of current to said heat generator in response to said temperature detector output signal.

Claim 18

The electrobalance system of claim 15 wherein said heat generator includes an electrical heater element.

Claim 19

The electrobalance system of claim 16 further comprising: a blocking diode coupled between said operational amplifier and said heater element for permitting current to be directed only from said amplifier to said heater element to provide heating current only when indicated.

Claim 20

The electrobalance system of claim 11 further comprising: a. a first housing for enclosing at least a portion of said beam displacement sensor; and b. a second housing for enclosing said heat generator and being shaped and oriented to substantially duplicate the heat radiating surfaces of said first housing, thereby presenting substantially the same heat radiation pattern at each of said ends of said beam.