Electronically monitored and controlled electrostatic discharge flooring system
AssigneeLoral Vought Systems Corporation
InventorsWilliam D. Wallace, Larry E. Smith
Life of this patent
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Abstract
The flooring structure of this invention controls electrostatic charges. The normal presence of moisture will not affect the floor structure's ability to control electrostatic charges. A moisture detector circuit will, however, indicate the presence of moisture, and can activate means for drying this moisture. The resistance of the flooring structure can be adjusted so that electrostatic charges are dissipated at different rates. Multiple floor structures with different resistance values can be placed side by side. Improper grounding of the flooring structure can be detected and corrected, and the resistance of the flooring structure system can be determined.
Claims18
An electrostatic charge controlling structure for covering a base surface, comprising, in sequence:
- a first layer of moisture resistant material;
- a second layer of at least substantially rigid wood material;
- a third layer of electrically conductive material;
- and
- a fourth layer of semiconductive member having electrical contact with said third layer.
A moisture sensor comprising:
- a moisture-variable resistive member whose resistance changes as a function of the level of moisture present in said moisture-variable resistive member;
- a first conductive member and a second conductive member being positioned such that current can flow from one of said first and said second conductive members through said moisture-variable resistive member to the other of said first conductive member and said second conductive member, said first conductive member being connected to a power supply;
- an output circuit;
- a control circuit having an input and an output, said input of said control circuit being connected to said second conductive member, said output of said control circuit being connected to said output circuit such that said control circuit does not activate said output circuit when the level of moisture present in said moisture-variable resistive member is a low level but does activate said output circuit when the level of moisture present in said moisture-variable resistive member is a higher level.
A moisture detector circuit which detects moisture, comprising:
- a conductive foam material which has less resistance when it absorbs moisture, said conductive foam material having first and second terminals;
- a variable resistance having a first terminal connected to a node and a second terminal connected to said first terminal of said conductive foam material;
- a transistor having a base and first and second terminals, said base being connected to said second terminal of said conductive foam material, said first terminal of said transistor being connected to an electrical ground, said second terminal of said transistor being connected to said node, said second terminal of said transistor being connected through said transistor to said electrical ground when a voltage is applied to said node and when the combined value of the resistance of the variable resistance and the resistance of the conductive foam material is low enough;
- and
- an output circuit connected between said node and said second terminal of said transistor, wherein said output circuit generates an output when there is a voltage between said node and said second terminal of said transistor.
Dependencies are inferred from the claim text.