Pressure sensor for detecting small pressure differences and low pressures
First Claim
1. A pressure sensor comprising:
- an extremely thin diaphragm plate produced by sintering a ceramic material that is subjected to a pressing force during a portion of the sintering, the diaphragm plate having a movable portion, mounted for movement in response to a pressure to be measured;
said diaphragm plate including an electrode, the position of which can be electronically sensed; and
wherein said diaphragm plate has a thickness smaller than 0.35% of the diameter of said movable portion thereof.
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Accused Products
Abstract
A capacitive pressure sensor of substantially ceramic material comprises a thick base plate (100), a front plate (140) having the same thickness as the base plate and a movable diaphragm (120) located between the front plate and the base plate. Capacitor electrodes (121b, 121a) are provided at the surface of the diaphragm facing the base plate and form a measurement capacitor. The diaphragm (120) is extremely thin and is produced by sintering a ceramic material such aluminum oxide. Owing to a pressing process used during the sintering a strong, very thin diaphragm is obtained having no mechanical stresses and fracture indications. It can be produced to have a very small thickness in order to provide pressure sensors having a high sensitivity, which can also for high-vacuum applications tolerate to be subjected to the atmospheric pressure. A shielding plate (110) can be inserted between the base plate (100) compensating the measurement capacitor. The shielding plate (110) can also be extremely thin, having a thickness down to a thickness corresponding to the thickness of a diaphragm (120).
197 Citations
20 Claims
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1. A pressure sensor comprising:
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an extremely thin diaphragm plate produced by sintering a ceramic material that is subjected to a pressing force during a portion of the sintering, the diaphragm plate having a movable portion, mounted for movement in response to a pressure to be measured; said diaphragm plate including an electrode, the position of which can be electronically sensed; and wherein said diaphragm plate has a thickness smaller than 0.35% of the diameter of said movable portion thereof. - View Dependent Claims (2, 3)
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4. A pressure sensor comprising:
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a substantially rigid base plate; a diaphragm plate, having at least a portion thereof which is movable in response to a pressure; a first cavity formed between the base plate and the diaphragm plate, for forming a measurement electrode pair; a shielding plate having a front surface, which forms a wall of the first cavity and is part of the measurement electrode pair, and a rear surface; and a second cavity formed between the rear surface of the shielding plate and a surface of the base plate, the walls of the second cavity forming a reference electrode pair, for compensating measurement values captured by the measurement electrode. - View Dependent Claims (5, 6, 7, 8, 9)
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10. A pressure sensor comprising:
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a pressure housing assembly made of substantially ceramic materials comprising a substantially rigid base plate, a front plate, and an extremely thin diaphragm plate produced by sintering a film of ceramic material that is subjected to a variable pressing force during a portion of the sintering, the diaphragm plate being at least partly movable in response to a pressure; said diaphragm plate being directly disposed between the base plate and the front plate to form a cavity between a side of the diaphragm plate and a side of the base plate, so that the walls of the cavity form a measurement electrode; and wherein the base plate and the front plate have substantially the same thickness and are made of substantially the same material. - View Dependent Claims (11)
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12. A pressure sensor, comprising:
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a body made of a first substantially ceramic material defining an interior volume, the body including a wall defining a first aperture; and a flexible diaphragm produced by sintering a second substantially ceramic material that is subjected to pressing force during a portion of the sintering, the diaphragm having a thickness smaller than 0.35% of the diameter of the diaphragm and the diaphragm dividing the interior volume into a first portion and a second portion, the first aperture being in fluid communication with the first portion, at least a first part of the diaphragm moving in a first direction when a pressure in the first portion increases relative to a pressure in the second portion, the first part of the diaphragm moving in a second direction when the pressure in the first portion decreases relative to the pressure in the second portion, the first part of the diaphragm and at least a first part of the body being characterized by a measurement capacitance, and the measurement capacitance changing in response to movement of the first part of the diaphragm relative to the first part of the body. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification