US 5,895,996 AGranted

Saw device

AssigneeSeiko Epson Corporation

InventorsMichiaki Takagi, Eishi Momosaki, Yoshinori Ikusaka

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Abstract

A SAW device utilizing elastic surface waves, in which the Q value indicating resonance sharpness is high, and which presents excellent frequency temperature characteristics and short-term frequency stability. In a SAW device according to the present invention, an IDT and two reflectors are in parallel in the propagation direction of the phase of the elastic surface waves. The IDT and reflectors are disposed to cover the power flow direction, which is the propagation direction of energy of the elastic surface waves, whereby the energy of the elastic surface waves is efficiently confined. Moreover, it becomes possible to manufacture the SAW device utilizing a piezoelectric crystal in which angle .theta. and angle .psi. indicating excellent frequency temperature characteristics are 25 to 45 degrees and 40 to 47 degrees, respectively. It is also possible to manufacture the SAW device utilizing a piezoelectric crystal where angle .psi. is related to angle .theta. such that .theta.=2.775.times.(.psi.-32.5)+6.5 where angle .theta. is in the range of 4 to 7 degrees.

Claims34

Dependent claims

A SAW device, comprising:

a plate-type piezoelectric material;
an interdigital transducer comprising M pairs of interdigital transducer electrodes made of a conductor having a film thickness H, the transducer electrodes being disposed on the plate-type piezoelectric material such that they are parallel to one another and extend in a direction substantially orthogonal to a first direction corresponding to a phase propagation direction;
first and second reflectors disposed on the plate-type piezoelectric transducer at opposite ends of the interdigital transducer, the first and second reflectors comprise a plurality of reflector conductors that extend in a direction substantially parallel to the transducer electrodes;
and
a width of the reflector conductors extending substantially orthogonal to the first direction and being greater than a width of the transducer electrodes and all reflector conductors intersecting a first line extending in a direction that approximately corresponds to a power flow direction, the first line approximately positioned at a distal extent of said interdigital transducer electrodes in a third direction approximately perpendicular to said power flow direction, and all reflector conductors intersecting a second line extending in a direction that approximately corresponds to a power flow direction, the second line approximately positioned at a distal extent of said interdigital transducer electrodes in a fourth direction opposite said third direction.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/647,921Filed 29 May 1996
Priority: JP 6-23521029 Sep 1994
Granted: 20 Apr 1999
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H03H 9/25
Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators: constructional features of resonators using…
H03H 9/02543
Of surface acoustic wave devices: characteristics of substrate, e.g. cutting angles
H03H 9/02551
Characteristics of substrate, e.g. cutting angles: of quartz substrates
H03H 9/02834
Means for compensation or elimination of undesirable effects: of temperature influence