Capacitive vacuum measuring cell
First Claim
1. A capacitive vacuum measuring cell including:
- a. a first housing body (1) made of Al2O3 ceramic material;
b. a membrane (2) made of Al2O3 ceramic material and arranged proximate to said first housing body, said membrane being substantially planar and having a peripheral edge, the peripheral edge of said membrane being joined by a first edge seal to said first housing body in such a way that a reference vacuum chamber (25) is created between said first housing body and said membrane, said membrane having first and second opposing surfaces, the first surface of said membrane facing said first housing body, and said first housing body having a surface facing said membrane, said membrane having a diameter in a range of 5 to 80 mm, and said membrane having a thickness in a range of 10 μ
m to 250 μ
m, said membrane being composed of a material having a mean grain size that is ≦
20 μ
m, and said membrane having a cross-section including at least 2 grains thereacross;
c. a second housing body (4) made of Al2O3 ceramic material and located opposite said membrane (2), said second housing body (4) being joined to the peripheral edge of said membrane by a second edge seal, said second housing body together with said membrane forming a measurement vacuum chamber (26), said second housing body including a port (5) for connecting the vacuum measuring cell to a medium to be measured;
d. said first housing body, said second housing body, and said membrane being symmetrically and tightly connected along the peripheral edge of said membrane; and
e. an electrically-conductive material (7) coated upon the first surface of said membrane (2) and coated upon the surface of said first housing body (1) to constitute the measuring capacitance, the electrically-conductive material coated upon the first surface of said membrane being arranged at a distance of 2 μ
m to 50 μ
m from the electrically conductive material coated upon the first housing body.
5 Assignments
0 Petitions
Accused Products
Abstract
A capacitive vacuum measuring cell includes first and second ceramic housing bodies (1, 4) joined by an edge seal (3). A thin ceramic membrane (2) is supported between first and second housing bodies (1, 4) by the edge seal (3) at a small distance from the first housing body (1) creating a reference vacuum chamber (25) therebetween. An electrically conductive material (7) coats opposing surfaces of the first housing body (1) and the membrane (2) to form a capacitor. A measurement vacuum chamber (26) is provided between the membrane (2) and the second housing body (4). A port (5) communicates with the second housing body (4) to connect the measurement vacuum chamber (26) of the measuring cell to the medium to be measured. The membrane (2) is made from an Al2O3 slurry that is sintered in a first heating step, cooled, and then reheated to smooth the membrane.
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Citations
21 Claims
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1. A capacitive vacuum measuring cell including:
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a. a first housing body (1) made of Al2O3 ceramic material;
b. a membrane (2) made of Al2O3 ceramic material and arranged proximate to said first housing body, said membrane being substantially planar and having a peripheral edge, the peripheral edge of said membrane being joined by a first edge seal to said first housing body in such a way that a reference vacuum chamber (25) is created between said first housing body and said membrane, said membrane having first and second opposing surfaces, the first surface of said membrane facing said first housing body, and said first housing body having a surface facing said membrane, said membrane having a diameter in a range of 5 to 80 mm, and said membrane having a thickness in a range of 10 μ
m to 250 μ
m, said membrane being composed of a material having a mean grain size that is ≦
20 μ
m, and said membrane having a cross-section including at least 2 grains thereacross;
c. a second housing body (4) made of Al2O3 ceramic material and located opposite said membrane (2), said second housing body (4) being joined to the peripheral edge of said membrane by a second edge seal, said second housing body together with said membrane forming a measurement vacuum chamber (26), said second housing body including a port (5) for connecting the vacuum measuring cell to a medium to be measured;
d. said first housing body, said second housing body, and said membrane being symmetrically and tightly connected along the peripheral edge of said membrane; and
e. an electrically-conductive material (7) coated upon the first surface of said membrane (2) and coated upon the surface of said first housing body (1) to constitute the measuring capacitance, the electrically-conductive material coated upon the first surface of said membrane being arranged at a distance of 2 μ
m to 50 μ
m from the electrically conductive material coated upon the first housing body.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification