Glass breakage detector

Claim 2

In a glass breakage detector, a sensing element, means securing said element to the inside surface of the glass, the element extending from said securing means, the shape of said element being such that movement of said securing means by the shock wave attendant only upon glass breakage will set said element into strong resonant vibration principally parallel to the plane of the glass, the shape of said element further being such that it is relatively immune to movement of said securing means by vibrations normal to the glass plane, and means connected to said sensing element and movable from a normal set position to a triggered position in which it initiates an alarm, said last-mentioned means being responsive to said vibrations of the sensing element parallel to the glass plane to move to its triggered position and thus initiate an alarm.

Claim 3

The combination according to claim 1, said sensing element being a spiral resonant element fixed only at its inner end.

Claim 4

The combination according to claim 1, said sensing element having a crosS-sectional shape such that it is substantially more flexible in a plane parallel to the glass than normal to it.

Claim 5

The combination according to claim 1, said last-mentioned means comprising a member securable to the glass and spring-urged to move from a set position to a triggered position, and contact means controlled by the member in response to said movement, said sensing element holding the member in its set position and responsive only to said vibrations to release the member.

Claim 6

In a glass breakage detector, a base securable to the glass surface, switch means mounted on the base to initiate an alarm, switch actuating means rotatably mounted on the base and spring-urged from its set to its triggered position, and a curved spring fixed at one end and carrying a detent normally holding the member in its set position, the curved spring being so constructed as to be immune from excitation normal to the plane of the glass but responsive to the shock wave which accompanies glass shattering to release the member.

Claim 7

In a glass breakage detector, a base securable to the glass surface, switch means mounted on the base to initiate an alarm, switch actuating means rotatably mounted on the base and spring-urged from its set to its triggered position, and a curved spring fixed at one end and carrying a detent normally holding the member in its set position, the curved spring being so constructed as to be immune from excitation normal to the plane of the glass but responsive to the shock wave which accompanies glass shattering to release the member.

Claim 8

A glass breakage detector comprising a flat base secured to one surface of the glass, at least two spaced switch contacts carried by said base, a switch actuating member carried by said base to initiate an alarm, means constantly urging said member from a set position to a triggered position changing the conductive relation between said contacts, a detent normally holding said member in its set position, and an element secured to said base and connected to said detent, said element being so shaped as to be set into relatively strong resonant vibration principally in the plane of the glass in response to the shock wave transmitted to the base by the glass when it is fractured or shattered, whereby the detent will be moved to release the switch actuating member which is then permitted to move to its triggered position.

Claim 9

A glass breakage detector comprising a flat base secured to one surface of the glass, at least two spaced switch contacts carried by said base, a switch actuating member carried by said base to initiate an alarm, means constantly urging said member from a set position to a triggered position changing the conductive relation between said contacts, a detent normally holding said member in its set position, and an element secured to said base and connected to said detent, said element being so shaped as to be set into relatively strong resonant vibration principally in the plane of the glass in response to the shock wave transmitted to the base by the glass when it is fractured or shattered, whereby the detent will be moved to release the switch actuating member which is then permitted to move to its triggered position.

Claim 10

The combination according to claim 6, said sensing element comprising a spring of generally spiral shape having its inner end fixed to said base and its outer end free, the cross-sectional shape of this said spring being elongated in a direction normal to the glass plane.

Claim 11

The combination according to claim 7, said detent being carried by an intermediate portion of said spring.

Claim 12

The combination according to claim 8, the portion of said spring between its inner fixed end and said detent having the shape of an Archimedes spiral, the portion outwardly of the detent having the shape of an involute spiral.

Claim 13

The combination according to claim 8, the cross-sectional shape of said spring being rectangular, its outer end being curled around itself.

Claim 14

The combination according to claim 6, there being three contacts, said member being rotatably mounted on said base, said urging means comprising a helical spring.

Claim 15

In a glass breakage detector, a substantially flat base securable to the surface of a plane of glass by a bonding agent, a central post carried by said base, a cover removably securable to the outer end of said post to enclose the elements of the device, a contact support fixed to said post and carrying a plurality of circumferentially arranged contacts, a switch actuating member to initiate an alarm comprising a rotor rotatably mounted on said post, said rotor being movable between a set position in which it creates a certain conductive relation between said contacts and a triggered position in which another conductive relation is created, spring means constantly urging said rotor from its set to its triggered position, a pin carried by said rotor, a detent engageable with said pin to hold the rotor in the set position, a sensing element comprising a spiral spring fixed at its inner end to said post and carrying said detent at an intermediate portion, said spring having a rectangular cross-sectional shape with its long axis normal to the plane of the glass, whereby the spring will exhibit a high degree of immunity to vibrations normal to the plane of the glass but will be set into resonant vibration bY the shock wave created by glass breakage sufficiently to cause said detent to release said pin.

Claim 16

In a glass breakage detector, a substantially flat base securable to the surface of a plane of glass by a bonding agent, a central post carried by said base, a cover removably securable to the outer end of said post to enclose the elements of the device, a contact support fixed to said post and carrying a plurality of circumferentially arranged contacts, a switch actuating member to initiate an alarm comprising a rotor rotatably mounted on said post, said rotor being movable between a set position in which it creates a certain conductive relation between said contacts and a triggered position in which another conductive relation is created, spring means constantly urging said rotor from its set to its triggered position, a pin carried by said rotor, a detent engageable with said pin to hold the rotor in the set position, a sensing element comprising a spiral spring fixed at its inner end to said post and carrying said detent at an intermediate portion, said spring having a rectangular cross-sectional shape with its long axis normal to the plane of the glass, whereby the spring will exhibit a high degree of immunity to vibrations normal to the plane of the glass but will be set into resonant vibration bY the shock wave created by glass breakage sufficiently to cause said detent to release said pin.

Claim 17

The combination according to claim 12, there being three circumferentially spaced contacts, said rotor carrying a wiper contact connecting first and second fixed contacts when the rotor is in its set position and second and third fixed contacts when it is in its triggered position.

Claim 18

The combination according to claim 12, said pin being eccentrically carried by a rotatable member on said rotor, whereby the position of the pin may be adjusted with respect to the detent.

Claim 19

The combination according to claim 14, said pin being of half-round cross-sectional shape with a sharp edge engageable with a shoulder on the detent.

Claim 20

The combination according to claim 15, said detent having a beveled surface engageable by the rounded portion of the pin when rotated toward its set position.

Claim 21

The combination according to claim 12, said cover being provided with a window and visual indicia carried by the rotor and visible through said window to indicate the set and triggered rotor positions.

Claim 22

The combination according to claim 12, said base having an axial extension inside said cover, and electrical conductor recesses formed in said extension and leading to terminals on said contact support.

Claim 23

The combination according to claim 18, further provided with coacting means on said rotor and base limiting movement of the rotor in both directions.

Claim 24

The combination according to claim 19, said coacting means comprising an elongated recessed portion on the edge of said rotor adjacent said base extension.