Rotating piezoelectric transducer mounting

Claim 2

A force transducer comprising: an enclosure including a frame and a base; a plate-like piezo electric crystal mounted in said enclosure upright with respect to said base; means for mounting said crystal in position and for permitting rotation of said crystal in its own plane, said means for mounting comprising a seat on said base, and a spigot for transmitting a force to be measured to said crystal, said base and said spigot engaging opposite edge portions of said crystal, said spigot being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof; first support means including a flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said diaphragm laterally surrounding said spigot and engaging same; second support means which are laterally rigid and which are attached to said frame and to said spigot, said first and second support means each being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction and to clamp said crystal between said spigot and said base; and electrical connections to said crystal, said connections extending outside said enclosure.

Claim 3

A force transducer comprising: an enclosure including a frame and a base; a plate-like piezo electric crystal mounted in said enclosure upright with respect to said base; means for mounting said crystal in position and for permitting rotation of said crystal in its own plane, said means for mounting comprising a seat on said base, and a spigot for transmitting a force to be measured to said crystal, said base and said spigot engaging opposite edge portions Of said crystal, said spigot being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof; first support means including a flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said diaphragm laterally surrounding said spigot and engaging same; second support means including at least one resilient member engaging said frame and extending from said frame substantially parallel to said diaphragm to engage said spigot so as to apply a preset force to said crystal via said spigot to clamp said crystal between said spigot and said base, said first and second support means each being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction; and electrical connections to said crystal, said connections extending outside said enclosure.

Claim 4

A force transducer comprising: an enclosure including a frame and a base; a plate-like piezo electric crystal mounted in said enclosure upright with respect to said base; means for mounting said crystal in position and for permitting rotation of said crystal in its own plane, said means for mounting comprising a seat on said base, and a spigot for transmitting a force to be measured to said crystal, said base and said spigot engaging opposite edge portions Of said crystal, said spigot being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof; first support means including a flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said diaphragm laterally surrounding said spigot and engaging same; second support means including at least one resilient member engaging said frame and extending from said frame substantially parallel to said diaphragm to engage said spigot so as to apply a preset force to said crystal via said spigot to clamp said crystal between said spigot and said base, said first and second support means each being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction; and electrical connections to said crystal, said connections extending outside said enclosure.

Claim 5

A force transducer as claimed in claim 2, wherein the angular position of said crystal relative to the line of action of said force to be measured applied via said spigot to said crystal is such that the temperature coefficient of the relation between said force to be measured applied to said crystal and the resonant frequency of said crystal is substantially zero.

Claim 6

A force transducer as claimed in claim 3, wherein the angle between the X axis of said crystal and said line of force is substantially 40*.

Claim 7

A force transducer as claimed in claim 2, further comprising: means for adjusting the lateral position of said crystal in its plane.

Claim 8

A force transducer as claimed in claim 2, wherein said electrical connections are joined to said crystal by a conducting cement.

Claim 9

A force transducer as claimed in claim 6, wherein said conducting cement is lead borate impregnated with silver.

Claim 10

A force transducer as claimed in claim 2, wherein said electrical connections extend to said crystal from said spigot and said base.

Claim 11

A force transducer as claimed in claim 2, wherein said electrical connections include electrodes, each electrode extending over part of a respective broad face of said crystal, said electrodes encompassing a region through which passes said line of action of said force to be measured applied to said crystal via said spigot.

Claim 12

A force transducer as claimed in claim 2, wherein said enclosure is occupied by an inert gas.

Claim 13

A force transducer as claimed in claim 3, wherein electromechanical means are provided for relieving the loading of said crystal.

Claim 14

A force transducer as claimed in claim 11, wherein said electromechanical means comprises a solenoid which has an armature coupled to said spigot.

Claim 15

A force transducing system comprising: a force transducer as claimed in claim 2; an electrical oscillatory circuit of which the resonant frequency is determined by said crystal; and means for measuring said force to be measured applied to said crystal via said spigot in accordance with the difference between the resonant frequency when said crystal is loaded by said force and the resonant frequency when the loading of said crystal by said force is relieved.

Claim 16

A force transducing system as claimed in claim 13, further comprising: means are provided for periodically relieving the loading of said crystal.

Claim 17

A force transducing system as claimed in claim 13, wherein said means for measuring said force comprises a reversible counter arranged to count cycles of oscillation of said oscillatory circuit.

Claim 18

A force transducer comprising: an enclosure comprising a frame and a base; a plate-like piezo electric crystal mounted in said enclosure upright with respect to said base; means for mounting said crystal in position and for permitting rotation of said crystal in its own plane, said means for mounting comprising a seat on said base, and a spigot for transmitting a force to be measured to said crystal, said base and said spigot engaging opposite edge portions of said crystal, said spigOt being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof; first support means including a flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said diaphragm laterally surrounding said spigot and engaging same; second support means including a second flexible diaphragm engaging said frame and extending from said frame substantially parallel to said diaphragm to engage said spigot so as to apply a present force to said crystal via said spigot to clamp said crystal between said spigot and said base, said first and second support means being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction; and electrical connections to said crystal, said connections extending outside said enclosure.

Claim 19

A force transducer comprising: an enclosure comprising a frame and a base; a plate-like piezo electric crystal mounted in said enclosure upright with respect to said base; means for mounting said crystal in position and for permitting rotation of said crystal in its own plane, said means for mounting comprising a seat on said base, and a spigot for transmitting a force to be measured to said crystal, said base and said spigot engaging opposite edge portions of said crystal, said spigOt being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof; first support means including a flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said diaphragm laterally surrounding said spigot and engaging same; second support means including a second flexible diaphragm engaging said frame and extending from said frame substantially parallel to said diaphragm to engage said spigot so as to apply a present force to said crystal via said spigot to clamp said crystal between said spigot and said base, said first and second support means being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction; and electrical connections to said crystal, said connections extending outside said enclosure.

Claim 20

A force transducer comprising: an enclosure comprising a frame and a base; a plate-like piezo electric crystal which is mounted upright with respect to said base; means for mounting said crystal, said means for mounting comprising a seat disposed on said base and a spigot for transmitting a force to be measured to said crystal, said spigot being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof, said seat and said spigot engaging opposite edge portions of said crystal, whereby said crystal can be rotated in its own plane; a first flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said first diaphragm laterally surrounding said spigot and engaging same; a second flexible diaphragm which is fixed to said frame, said second diaphragm laterally surrounding said spigot and engaging same to apply a present force to said crystal to clamp said crystal between said spigot and said base, said first and second diaphragms being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction; electrical connections to said crystal, said connections extending outside said enclosure; and means for permitting said seat to swivel with respect to said base.

Claim 21

A force transducer comprising: an enclosure comprising a frame and a base; a plate-like piezo electric crystal which is mounted upright with respect to said base; means for mounting said crystal, said means for mounting comprising a seat disposed on said base and a spigot for transmitting a force to be measured to said crystal, said spigot being disposed in the plane of said crystal and aligned substantially with the center of the active area thereof, said seat and said spigot engaging opposite edge portions of said crystal, whereby said crystal can be rotated in its own plane; a first flexible diaphragm which is fixed to said frame and extends across it so as to complete said enclosure, said first diaphragm laterally surrounding said spigot and engaging same; a second flexible diaphragm which is fixed to said frame, said second diaphragm laterally surrounding said spigot and engaging same to apply a present force to said crystal to clamp said crystal between said spigot and said base, said first and second diaphragms being arranged to restrain said spigot resiliently in a longitudinal direction and rigidly in a lateral direction; electrical connections to said crystal, said connections extending outside said enclosure; and means for permitting said seat to swivel with respect to said base.