US4628222A — Protection of saw devices comprising metallized r…

Claim 1

Independent Claim 84 words

In a surface acoustic wave device having at least two thin film structures disposed on the surface of a substrate, there being a gap between said structures, said structures being arranged so that a surface acoustic wave traversing a first of said structures is communicated across said gap to the second of said structures, and a thin film loop electrically shunting said gap to prevent cracks in the gap region of said substrate from being induced during fabrication of said surface acoustic wave device.

Claim 2

Dependent Claim 84 words

In a surface acoustic wave device having at least two thin film structures disposed on the surface of a substrate, there being a gap between said structures, said structures being arranged so that a surface acoustic wave traversing a first of said structures is communicated across said gap to the second of said structures, and a thin film loop electrically shunting said gap to prevent cracks in the gap region of said substrate from being induced during fabrication of said surface acoustic wave device.

Claim 3

Dependent Claim 84 words

The means for preventing cracks of claim 1 wherein said thin film structures are disposed along a longitudinal axis of said surface acoustic wave device, a surface acoustic wave generally traversing along said longitudinal axis, said loop including a pair of electrically conductive legs, each leg of said pair being disposed opposite the other leg of said pair on opposite sides of said gap and generally perpendicular to said longitudinal axis and means electrically bridging the ends of said legs remote from said gap.

Claim 4

Dependent Claim 24 words

The means for preventing cracks of claim 1 wherein said loop in an electrically conductive microstrip interconnecting said thin film structures across said gap.

Claim 5

Dependent Claim 27 words

The means for preventing cracks of claim 1 wherein the resistance of said loop is significantly greater than the output impedance of said surface acoustic wave device.

Claim 6

Dependent Claim 79 words

In a surface acoustic wave convolver having at least one thin film parabolic horn and an interaction channel disposed on a substrate, said horn having a relatively wide input end for receiving a surface acoustic wave incident thereon and a relatively narrow output end which communicates with said interaction channel across a gap and along the surface of said substrate, and a thin film loop electrically shunting said gap to prevent cracks in the gap region of said substrate.

Claim 7

Dependent Claim 79 words

In a surface acoustic wave convolver having at least one thin film parabolic horn and an interaction channel disposed on a substrate, said horn having a relatively wide input end for receiving a surface acoustic wave incident thereon and a relatively narrow output end which communicates with said interaction channel across a gap and along the surface of said substrate, and a thin film loop electrically shunting said gap to prevent cracks in the gap region of said substrate.

Claim 8

Dependent Claim 42 words

The means for preventing cracks of claim 5 wherein said thin film loop extends generally perpendicular to the direction of travel of said surface acoustic wave in said convolver at the interface of the loop with said horn and said interaction channel.

Claim 9

Dependent Claim 27 words

The means for preventing cracks of claim 5 wherein the resistance of the loop is significantly greater than the output impedance of said surface acoustic wave convolver.

Claim 10

Independent Claim 86 words

A device comprising a dielectric substrate and metallized regions superimposed on the substrate constituting elements of the device, said device including at least one resistive link connected between at least two other mutually insulated metallized regions, said link being inessential to the required function of the device when subsequently connected into an external circuit but acting to prevent the establishment of a damaging electric field between adjacent ones of said metallized regions due to unwanted dielectric charge storage not arising from in-circuit operation of the device.

Claim 11

Independent Claim 86 words

A device comprising a dielectric substrate and metallized regions superimposed on the substrate constituting elements of the device, said device including at least one resistive link connected between at least two other mutually insulated metallized regions, said link being inessential to the required function of the device when subsequently connected into an external circuit but acting to prevent the establishment of a damaging electric field between adjacent ones of said metallized regions due to unwanted dielectric charge storage not arising from in-circuit operation of the device.

Claim 12

Dependent Claim 16 words

A device as claimed in claim 8 wherein the two metallized regions are adjacent one another.

Claim 13

Dependent Claim 14 words

A device as claimed in claim 9 wherein the links are strips of metallizing.

Claim 14

Dependent Claim 23 words

A device as claimed in claim 10 wherein the strips of metallizing are formed at the same time as the two metallized regions.

Claim 15

Dependent Claim 24 words

A device as claimed in claim 11 wherein all the metallized regions which constitute elements or part elements are interconnected by said resistive links.

Claim 16

Dependent Claim 37 words

A device as claimed in claim 11 having an external circuit connection between the metallized regions linked by said link and having a break in said link, said break having been made after making said external connection.

Claim 17

Dependent Claim 29 words

A device as claimed in claim 9 wherein the resistive links are constituted by a substantially uniform relatively high-resistance coating of material extending between the elements of the device.

Claim 18

Dependent Claim 29 words

A device as claimed in claim 14 wherein the high-resistance coating is a coating of metallizing deposited substantially uniformly on the substrate before the metallizing which forms the elements.

Claim 19

Dependent Claim 26 words

A device as claimed in claim 15 wherein the high-resistance coating is one which serves to improve the adhesion of the metallizing which forms the elements.

Claim 20

Dependent Claim 29 words

A device as claimed in claim 16 wherein the substrate is selected from the group consisting of pyroelectric and piezoelectric substrates and substrates which are both pyroelectric and piezoelectric.

Claim 21

Dependent Claim 15 words

A device as claimed in claim 17 wherein the device is an acoustic wave device.

Claim 22

Dependent Claim 65 words

A device as claimed in claim 11 in which the device is a surface acoustic wave convolver whereof the elements comprise a pair of input interdigital transducers, a pair of horns which receive and focus the respective transducer outputs, and an acoustic waveguide whose opposite ends receive the respective horn outputs, said device including said resistive links at least between each horn and the waveguide.

Claim 23

Dependent Claim 33 words

A device as claimed in claim 19 and also including said resistive links formed between each horn and its adjacent input transducer and between the two sets of digits of each input transducer.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-12-08	1990-06-09	1990-12-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-12-08	1994-06-09	1994-12-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-12-08	1998-06-09	1998-12-09	$7700.00	Window Closed / Lapsed

Protection of saw devices comprising metallized regions on dielectric substrates

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