GB1209505A - Electric alarm clock - Google Patents

Abstract

1,209,505. Electric alarm clocks. SUNBEAM CORP. March 15, 1968 [April 26, 1967], No. 12839/68. Heading G3T. [Also in Division G1] In an electric alarm clock an electric lamp 27, Fig.5, is energized simultaneously with the sounding of an audible alarm, and an alarm cutoff device is actuated by increasing the amount of light from the lamp 27, as by reflecting the light rays 29 by a hand 113, received by a photoelectric cell 25 associated with electric circuitry operating the cut-off device. The alarm mechanism comprises a gear-wheel 40b, Fig. 4 having a hub 40 carrying an alarm indicator hand 18 Fig. 1 (not shown) and held in a set position by a spring disc 42. When the alarm is to be sounded apertures in the low gear 43 register with projections 40c on the wheel 40b, so that the gear 43 is moved axially by a lever 45 under the action of a spring portion 45f. The lever 45 then releases a lever 57, Fig.2, to permit it to be vibrated via a tab 57a by a toothed wheel 60 on the seconds shaft so that a hammer 58 on the lever 57 strikes the alarm bell 55. In addition to the control by the light actuated cut-off device the alarm is controlled by pulling a plate 62 by means of a chain 75 downwardly against the action of a spring 66 so that a lug 62v on the plate rotates a toothed wheel 70 having alternate shallow and deep notches 72, 73. When the lug 62a engages a deep notch 73 the alarm is operative, but when it engages a shallow notch 72 a tab 62e on the plate 62 engages a tab 57c on the lever 57 to disengage the tab 57a from the toothed wheel 60 to render the alarm ineffective. The lamp 27 of the light actuated alarm cut-off device is energized by closure of a switch 82 by an extension 45d of the lever 45 when the latter is actuated to sound the alarm. The light from the lamp 27 reflected by a hand 113 on to the photo-electric cell 25 produces an electrical pulse which is differentiated by a resistance capacity network 105, 107 Fig. 6 (not shown) and applied to the gate of a field effect transistor controlling a silicon controlled rectifier so that the latter is rendered conducting to energize a solenoid 97 and actuate a plunger 98 to move the plate 62 to stop the alarm. In an alternative clock in which the alarm consists of an electrical buzzer 128 Fig. 8 (not shown), energized when both switches 82 and 83 are closed, a second photoelectric cell is provided which receives ambient light only. The two photo-electric cells are arranged in a Wheatstone network which provides a signal when light reflected by a hand 113 is received by the first cell only. This signal is applied via a transistor circuit to the gate of a silicon controlled rectifier to energize the solenoid 97 to open the switch 83 to stop the alarm.