Patent GB-1272636-A (GB)
Title: Improvements in and relating to piezoelectric assemblies
IPC: F23Q2/28
Filed: 1969-05-21
Abstract: 1,272,636. Piezo-electric generators. MATSUSHITA ELECTRICAL INDUSTRIAL CO. Ltd. 21 May, 1969 [21 May, 1968 (2)], No. 25896/69. Heading H2A. A piezo-electric signalling device or igniter has a pair of stretchers which engage the element 32 sequentially to produce discrete output pulses. In the construction shown in Figs. 1 and 4, the element is housed in a casing 20 open at one end to receive a plunger 26 carrying the strikers 64, 66. Striker 66 is slidable on a rod 62 against a spring 68 and striker 64 extends forwardly of and partly surrounds striker 66 and is slidable against a second spring 74. In the inoperative position of the plunger, latch pins 54, 56 on the two strikers locate in notches 50, 52 in a slot 48 in casing 20. When the plunger is depressed against a return spring 40 both springs 68, 74 are compressed until a cam face (80) on the plunger lifts the latch pin 54 from its notch 50 and allows spring 74 to urge the striker 64 into engagement with the element. As striker 64 moves forward a cam surface 73 thereon lifts the latch pin 52 and allows the striker 64 to be urged by its spring 68 into engagement with the element. Two output pulses are thus produced at a time interval independent of the operation of the plunger. The time interval between the pulses may be varied by an adjusting screw (30) which slides the element towards or away from the strikers to vary the stroke of the latter. Fig. 7 shows a modified actuating mechanism wherein after the cam face 80<SP>1</SP> on the plunger 26<SP>1</SP> has released the first latch pin 54<SP>1</SP>, this pin, as it moves forward, strikes a cam surface 112 on a pivoted lever 108 which rotates anticlockwise in the figure to release the second latch pin 56<SP>1</SP>. The lever is pivoted on an eccentric which is adjustable to move the lever towards or away from the casing 20<SP>1</SP>, thereby varying the time between release of the latch pins and hence the time between the pulses. In the further embodiment shown in Fig. 11, a pivoted actuating lever 26<SP>11</SP> carries pivoted strikers 64<SP>11</SP>, 66<SP>11</SP> urged by torsion springs 74<SP>11</SP>, 68<SP>11</SP> against pivoted latch members 50<SP>11</SP>, 5211. Rotation of the lever 26<SP>11</SP> in the direction C against return spring 40<SP>11</SP> first stresses springs 7411, 68<SP>11</SP> until an edge portion 80<SP>11</SP> on the lever strikes latch member 50<SP>11</SP> and causes it to release striker 6411 towards element 3211. As the striker moves, a pin 136 on an arm 138 thereon engages a trip lever 140 which in turn engages the second latch member 5211 and causes it to release striker 66<SP>11</SP>. On release of the lever 26<SP>11</SP>, a projection 72<SP>11</SP> thereon returns the strikers until they are reengaged by the latch members. The time interval between the pulses can have two valves in this embodiment determined by inner and outer positions of a push-button 148 which, through the intermediary of a slide bar 146, moves the pivot shaft 142 of the trip lever 140 to one of two positions in which the distance travelled by the pin 136 before it engages the trip lever is different from the distance travelled in the other position.