Lever actuator comprising a longitudinal-effect electroexpansive transducer and designed to prevent actuation from degrading the actuator

Claim 2

In a lever actuator comprising a frame member, an elongated longitudinal-effect electroexpansive transducer (51) block/having a block axis and first and second end surfaces orthogonally of said axis, and field generating means for generating an (51) electric field having a direction in said transducer block / parallel to said axis to produce a reversible strain in said transducer block and thereby to give rise to a translational displacement of said first end surface relative to said second end surface in a direction parallel to said axis, said frame member comprising (52) (53) a base portion, a lever portion/having fulcrum, power, and weight points with said fulcrum and said power points disposed on a (58) median plane including said axis, a resilient portion/connecting (52) said fulcrum point to said base portio (52), coupling means for operatively coupling said first end surface to said power point, and connecting means for connecting said second end surface to said base portion to make said displacement actuate said lever portion and thereby to move said weight point, the improvement wherein said coupling means comprises a substantially plate-shaped primary portion(56) which operatively couples said first end surface to said power point and has a pair of primary principal surfaces disposed perpendicular to said plane and substantially parallel to said axis.

Claim 3

A lever actuator as claimed in Claim 1, wherein (56) said primary portion/is lengthwise rigid and thicknesswise resilient.

Claim 4

A lever actuator as claimed in Claim 2, wherein said primary principal surfaces are disposed substantially on both sides of said axis.

Claim 5

wherein, 4. A lever actuator as claimed in any of claims 1 to 3, said connecting means comprises a substantially plate-shaped (57) secondary portion/which operatively connects said second end (52) surface to said base portion/and has a pair of secondary principal surfaces disposed substantially on extensions of said primary principal surfaces, respectively, wherein

Claim 6

A lever actuator as claimed in any of claims 1 to 4,/ a straight line defined by said fulcrum and said power points is substantially perpendicular to said axis.

Claim 7

A lever actuator as claimed in Claim 4, wherein (56, 57 respectively) at least one of said primary and said secondary portions/comprises (67) a thicker and a thinner part, said thicker part/having a pair of principal surfaces which serve as the two principal surfaces of said one of the primary and the secondary portions, said thinner (68) part/being rendered integral with said thicker part and having a thickness thinner than said thicker part.

Claim 8

wherein 7. A lever actuator as claimed in any of.claims 1 to 6,/ said coupling means further comprises a first cup-shaped portion formed integral with said primary portion and adpated to snugly receive that portion of said transducer block which is adjacent to said first end surface, said connecting means comprising a second cup-shaped portion formed integral with said secondary portion and adapted to snugly receive that portion of said transducer block which is adjacent to said second end surface.

Claim 9

wherein 8. A lever actuator as claimed in any of claims 1 to 6,/ said coupling means further comprises a first plate connector piece having an outline coincident with said first end surface and formed integral with said primary portion and a first discrete (Claim 8 continued) cup-shaped insulating piece haying a first bottom surface and adapted to snugly receive said first plate connector piece in contact with said first bottom surface and also to receive that portion of said transducer block which is adjacent to said first end surface, said first bottom surface having a first opening through which said primary portion extends, said connecting means further comprising a second plate connector piece having an outline coincident with said second end surface and formed integral with said secondary portion and a second discrete cup-shaped insulating piece having a second bottom surface and adapted to snugly receive said second plate connector piece in contact with said second bottom surface and also to receive that portion of said transducer block which is adjacent to said second end surface, said second bottom surface having a second opening through which said secondary portion extends.

Claim 10

herein 9. A lever actuator as claimed in any of claims 1 to 8,/ said resilient portion comprises a substantially plate-shaped tertiary portion which connects said fulcrum point to said base portion and having a pair of tertiary principal surfaces disposed perpendicular to said plane and forming, when said electric field is not generated in said transducer block, a predetermined angle with said axis.

Claim 11

wherein 10. A lever actuator as claimed in any of claims 1 to 8,/ said base portion has a pair of coplanar surfaces forming a prescribed angle with said axis when said,electric field is not generated in said transducer block, said resilient portion comprising a bar-shaped member which has a bar axis disposed perpendicular (Claim 10 continued) to said plane and comprises an intermediate portion fixed to said fulcrum point and a pair of end portions rendered torsibly integral with said intermediate portion along said bar axis and fixed to said coplanar surfaces, respectively.

Claim 12

A lever actuator as claimed in any one of Claims 1 through 10, wherein said strain is a reversible extension.

Claim 13

A lever actuator as claimed in Claim 11, further comprising restricting means for restricting an excursion of the lever portion actuated by said displacement so that a tensile stress developed in said transducer block has a maximum magnitude which is about from one fourth to one fifth of a magnitude of a compressive stress developed in said transducer block in the absence of said restricting means at an instant at which said lever portion starts to move in response to said displacement.

Claim 14

A lever actuator as claimed in Claim 11 or 12, further comprising spring means for urging said first end surface towards said second end surface along said block.axis to develop a stationary compression in said transducer block with a magnitude which is about from one fourth to one fifth of a magnitude of a variable compressive stress developed in said transducer block in the absence of said spring means at an instant at which said lever portion starts to move in response to said displacement.

Claim 15

A lever actuator as claimed in Claim 13, wherein said spring means is a coil spring having a pair of coil ends, said coupling means further comprising a lug portion rendered integral with said primary portion and projected transversely of said primary principal surfaces, said coil ends being held (Claim 14 continued) by said base portion and said lug portion, respectively.

Claim 16

A lever actuator as claimed in Claim 13, wherein said spring means is a leaf spring having free and fixation ends, said coupling means further comprising a lug portion rendered integral with said primary portion and projected transversely of said primary principal surfaces, one of said base portion and said lug portion having a portion surface which is disposed to face the other of said base portion and said lug portion perpendicularly of said plane and slidably receives said free end, said fixation end being fixed to said other of the base portion and the leg portion.

Claim 17

A lever actuator as claimed in Claim 13, wherein said spring means is a coil spring having a pair of coil ends, said base portion having a base portion surface perpendicularly of said plane, said lever portion having a lever portion surface facing said base portion surface substantially parallel thereto, said coil ends being received on said base portion surface and said lever portion surface, respectively.

Claim 18

A lever actuator as claimed in Claim 16, wherein one of said base portion surface and said lever portion surface is a bottom surface of an indent for snugly receiving one of said coil ends.

Claim 19

A lever actuator as claimed in Claim 13, wherein said spring means is a leaf spring having free and fixation ends, one of said base portion and said lever portion having a portion surface which is disposed to face the other of said base portion and said lever portion perpendicularly of said plane and transversely (Claim 18 continued) of said block axis and slidably receives said free end, said fixation end being fixed to said other of the base portion and the lever portion.

Claim 20

A lever actuator as claimed in any of claims 1 to 18, wherein said frame member further comprises an arm portion having first and second predetermined points, a springy portion connecting said first predetermined point to said base portion, and an additional portion which has a portion axis and connects said second predetermined point to said weight point with said portion axis interposed between said second predetermined point and said weight point.

Claim 21

A lever actuator as claimed in Claim 19, wherein said strain is a reversible extension, said lever actuator further comprising restricting means for rectricting an excursion of the lever portion actuated by said displacement so that a tensile stress developed in said transducer block has a maximum magnitude which is about from one fourth to one fifth of a magnitude of a compressive stress developed in said transducer block in the absence of said restricting means at an instant at which said lever portion starts to move in response to said displacement.

Claim 22

A lever actuator as claimed in Claim 19, wherein said strain is a reversible extension, said lever actuator further comprising spring means for urging said first end surface towards said second end surface along said block axis to develop a stationary compressin on said transducer block with a magnitude which is about from one fourth to one fifth of a magnitude of a variable compressive stress developed in said transducer block in the absence of said spring means at an instant at which said lever (Claim 21 continued) portion starts to move in response to said displacement.

Claim 23

A lever actuator as claimed in Claim 21, wherein said spring means is a coil spring having a pair of coil ends, said base portion having a base portion surface perpendicularly of said plane, said arm portion having an arm portion surface facing said base portion surface substantially parallel thereto, said coil ends being received by said base portion surface and said arm portion surface, respectively.

Claim 24

A lever actuator as claimed in Claim 22, wherein at least one of said base portion surface and said arm portion surface is a bottom surface of an indent for snugly receiving one of said coil ends.

Claim 25

A lever actuator as claimed in Claim 21, wherein said spring means is a leaf spring having free and fixation ends, one of said base portion and said rod portion having a portion surface which is disposed to face the other of said base portion and said rod portion perpendicularly of said plane and slidably receives said free end, said fixation end being fixed to said other of the base portion and the arm portion.

Claim 26

A lever actuator as claimed in Claim 21, wherein said spring means is a coil spring having a pair of coil ends, said lever portion having a lever portion surface perpendicularly of said plane and transversely of said axis, said arm portion having an arm portion surface facing said lever portion surface substantially parallel thereto, said coil ends being received by said lever portion surface and said arm portion surface, respectively.

Claim 27

A lever actuator as claimed in Claim 25, wherein at least one of said lever portion surface and said arm portion surface is a bottom surface of an indent for snugly receiving one of said coil ends.

Claim 28

27, A lever actuator as claimed in Claim 21, wherein said spring means is a leaf spring having free and fixation ends, one of said lever portion and said arm portion having a portion surface which is disposed to face the other of said lever portion and said arm portion perpendicularly of said plane and slidably receives said free end, said fixation end being fixed to said other of the lever portion and said arm portion.

Claim 29

wherein 28. A lever actuator as claimed in any of claims 1 to 27,/ said frame member further comprises a first arm portion having first, second, and third predetermined points with said first and said second predetermined points disposed on said plane, a second arm portion having fourth and fifth predetermined points, a springy portion connecting said first predetermined point to said base portion, a substantially plate-shaped secondary portion which has a pair of secondary principal surfaces disposed substantially parallel to said primary principal surfaces and operatively couples said first end surface to said second predetermined point with said primary principal surface pair and said secondary principal surface pair disposed on both sides of said axis, a first additional portion which has a first portion axis and connects said weight point to said fourth predetermined point with said first portion axis interposed between said weight point and said fourth predetermined point, and a second additional portion which has a second portion axis and connects said third and said fifth predetermined points (Claim 28 continued) with said second portion axis interposed between said third and said fifth predetermined points, said translational displacement moving said third predetermined point substantially in a direction of movement of said weight point with a different sense.

Claim 30

A lever actuator as claimed in Claim 28, wherein first and second forces exerted by said primary and said secondary portions onto said first end surface are substantially equal to each other in magnitude, substantially parallel to said block axis, and towards said first end surface

Claim 31

A lever actuator as claimed in Claim 29, wherein said base portion comprises a pair of leg portions on both sides of said transducer block, said leg portions having leg end surfaces, respectively, said resilient portion connecting said fulcrum point to one of said leg end surfaces, said springy portion connecting said first predetermined point to the other of said leg end surfaces.

Claim 32

A lever actuator as claimed in Claim 30, wherein said base portion further comprises a beam portion integrally uniting said leg portions at parts remote from said leg end surfaces to provide said base portion a shape of a channel,

Claim 33

A lever actuator as claimed in any of claims 28 to 31, wherein each of said primary and said secondary portions comprises a thicker and a thinner part, said thicker part having a pair of principal surfaces which serve as the two principal surfaces of said each of the primary and the secondary portions, said thinner part being rendered integral with said thicker part and having a thickness thinner than said thicker part.

Claim 34

A lever actuator as claimed in any one of Claims 28 through 32, wherein said strain is a reversible extension, said lever actuator further comprising restricting means for restricting an excursion of the lever portion actuated by said displacement so that a tensile stress developed in said transducer block has a maximum magnitude which is about from one fourth to one fifth of a magnitude of a compressive stress developed in said transducer block in the absence of said restricting means at an instant at which said lever portion starts to move in response to said displacement.

Claim 35

A lever actuator as claimed in any one of Claims 28 through 32, wherein said strain is a reversible extension, said lever actuator further comprising spring means between said base portion and said second arm portion, said spring means being for urging said first end surface towards said second end surface along said block axis to develop a stationary compressive stress in said transducer block with a magnitude which is about from one fourth to one fifth of a magnitude of a variable compressive stress developed in said transducer block in the absence of said spring means at an instant at which said lever portion starts. to move in response to said displacement.

Claim 36

A lever actuator as claimed in Claim 34, wherein said spring means is a coil spring having a pair of coil ends held by said base portion and said second arm portion, respectively.

Claim 37

A lever actuator as claimed in Claim 34, wherein said spring means is a leaf spring having free and fixation ends, one of said base portion and said second arm portion having a portion surface which is disposed to f.ce the other of said base (Claim 36 continued) portion and said second arm portion perpendicularly of said median plane and slidably receives said free end, said fixation end being fixed to said other of the base portion and the second arm portion. f

Claim 38

In a printer head comprising a holder and a plurality of printer units, each printer unit comprising a printing element and a printing element actuator which comprises a frame member, an elongated longitudinal-effect electroexpansive transducer bloch having a block axis and first and second end surfaces orthogonally of said axis, and field generating means for generating an electric field having a direction in said transducer block parallel to said axis to produce a reversible extension in said transducer block and thereby to give rise to a translational displacement of said first end surface relative to said second end surface in a direction parallel to said axis, said frame member comprising a base portion, a lever portion having fulcrum, power, and weight points with said fulcrum and said power points disposed on a median plane including said axis and with said printing element attached to said weight point, first coupling means for operatively coupling said fulcrum point to said base portion, second coupling means for operatively coupling said first end surface to said power point, and connecting means for connecting said second end surface to said base portion to make said displacement actuate said lever portion and thereby to move said printing element, said holder holding the printing element actuators of the respective printer units with the printing elements of the respective printer units arranged to reach predetermined printing positions, respectively, (Claim 37 continued) the improvement wherein the coupling means in each printing element actuator comprises a substantially plate-shaped portion which couples in said each printing element actuator the first end surface to the power point and has a pair of principal surfaces disposed perpendicular to the median plane and substantially parallel to the block axis.

Claim 39

A printer head as claimed in Claim 37, further comprising restricting means for restricting an excursion of the lever portion actuated in each printing element actuator by the displacement of the first end surface relative to the second end surface so that a tensile stress developed in said transducer block has a maximum magnitude which is about from one fourth to one fifth of a magnitude of a compressive stress developed in said transducer block in the absence of said restricting means at an instant at which the lever portion starts to move in response to the displacement.

Claim 40

A printer head as claimed in Claim 38, wherein said restricting means comprises an arm fixed to the base portion of at least one of said printing element actuators.

Claim 41

wherein 40. A printer head as claimed in any of claims 37 to 39, said holder comprises a shoulder portion which serves as said restricting means for at least one of said printing element actuators.

Claim 42

wherein 41. A printer head as claimed in any of claims 37 to 40,/ said printing elements comprising a rod portion, wherein said bolder comprises a rod guide having holes through which the rod portions of the respective printing elements are slidable, said rod guide being positioned to serve as said restricting means.