US3320739A - Alarm clock - Google Patents

Description

y 3, 1967 B. KLEINERMAN 3,320,739

ALARM CLOCK Filed May 13 1965 2 Sheets-Sheet l A as May 23, 1967 B. KLEINERMAN ALARM CLOCK 2 Sheets-Sheet 2 Filed May 13, 1965 United States Patent 3,320,739 ALARM CLOCK Ben Kleinerman, New Hyde Park, N.Y., assignor to Jerry G. Bechhofer, New York, N.Y. Filed May 13, 1965, Ser. No. 455,434 7 Claims. (ill. 58-38) This invention relates to alarm clocks. One of the first reactions of sleepers, on hearing the buzzer of an alarm clock, is to grope drowsily for the clock to shut it off. This is, for many, a wearing, unpleasant and strenuous procedure, particularly if the person has just been roused from a deep sleep.

It is an object of this invention to simplify the operation of shutting off the alarm.

Another object of this invention is to provide an alarm clock whose alarm may be shut off merely by the approach of the hand of the half-awakened person, without touching the clock.

Other objects of this invention will be apparent from the following detailed description and claims.

In accordance With one aspect of this invention, an alarm clock having a time-controlled alarm is provided with alarm-inactivating means responsive to changes in the electromagnetic field around the clock resulting from the approach of the human hand to a zone near the clock. In a preferred form, the device is responsive to the body capacitance of the user and includes normally passive means responsive to activating signals'and a capacitively effective element cooperable with body capacitance for coupling the activating signals to the normally passive means to cause the alarm to be shut oil. The normally passive means, in a preferred construction, is responsive to low frequency and has a trigger electrode which, when coupled by the body capacitance to the signal generated by adjacent AC. power wires, permits an alarm-deactivating current to pass through the normally passive means. The trigger electrode may be part of a device such as a thyratron, a silicon-controlled rectifier, a flip-flop or the like; such a device may form part of -a circuit containing also a solenoid operable to shut off the alarm. Ordinarily no current can flow through this circuit, but when body capacitance is brought into proximity to the capacitive element which is connected to the trigger electrode, the thyratron, silicon controlled rectifier or similar device fires, permitting current to flow and thus operating the solenoid. The trigger electrode is advantageously preset at a bias greatly exceeding the level at which the device Will fire with the normal energization of its output circuit; this minimizes the effect of transients in the power supply.

One form of the invention is illustrated in the accompanying drawing in which:

FIGURE 1 is a front view of a clock;

FIGURE 2 is a rear view of the clock;

FIGURE 3 is a schematic view of a portion of the alarm mechanism;

FIGURE 4 is a view like that of FIG. 3, showing the position of the parts during the operation of an alarm repeat cycle;

FIGURE 5 is a schematic view of another portion of the alarm mechanism; and

FIGURE 6 is a circuit diagram of an embodiment of this invention.

In one preferred form, the device of this invention is produced by modifying an electric alarm clock 11 of the usual type having an insulating plastic housing 12, a face 13 and hands 14 driven by a motor 16 operating on 60 c.p.s. alternating current supplied through leads 17 and 18 connected to the corresponding prongs 20, 19, of a plug 22 fitting in a household electrical receptacle 23.

As is conventional, the magnetic field of the motor 16 is created by a winding 24 around a laminated field core 26 which also acts to actuate an alarm buzzer hammer 27 when the alarm is to be sounded. The hammer 27 is resiliently urged toward the adjacent portion 28 of the core, but is normally maintained in an inoperative position, a short distance away from portion 28 until the preset time for sounding the alarm buzzer is reached. When this preset time is reached the hammer is permitted to move rapidly toward the core.

More particularly, the hammer 27 is mounted near the head end of a resilient lever 29, of leaf spring material rigidly supported at its tail end 31. The hammer is normally maintained in its inactive position by a pivoted pusher element 32 (FIG. 5) which presses upwardly against the lever 29 near its head end so as to bend that lever upwardly against the force of its leaf spring material. The pusher element 32 is itself maintained in its alarm-inactivating position by the conventional alarm clockwork (indicated generally as 34, FIG. 5), which comprises an alarm cam 36 mounted on a clockworkdri-ven gear 37 and having a tip 38 which engages one face of a coaxially mounted wheel 39 having an aperture 41 and carrying, on its other face, a pin 42 which presses against the pusher element 32. At the preset time the rotation of the gear 37 brings the tip 38 of the alarm cam 36 opposite the aperture 41 of the wheel 39, permitting the wheel to approach the gear, and thus releasing the lever 29 so that the hammer may move, under the resilient force in the lever toward the core 26 to sound the alarm. Unless shut off manually, the alarm continues to sound for a relatively long period of time until further rotation of the gear 37 and corresponding movement of the cam 36 causes the wheel 39 to be pushed by the alarm cam a sufiicient distance from the gear so that the hammer is forced (by the effect of the movements of pin 42 and pusher element 32) to an inoperative position at theclose of the alarm period.

The alarm may be shut off manually by the usual reset rod 43, which has a cam portion engaging the lever 29 so as to lift the hammer 27 away from the core 26 when the reset rod is pushed in by the user. Usually the reset rod is accessible to manual operation from the back of the clock.

It is also common for alarm clocks to have an alarm repeat control mechanism actuated by an easily accessible push button 44 (FIG. 1) at the top of the clock.

This feature makes it possible for the awakened sleeper to shut off the alarm without immediately making the onerous effort of moving the reset rod 43. If after the predetermined alarm-repeat time (say, 5 minutes) the reset rod still has not been operated manually, the alarmrepeat control device permits the alarm to sound again, and so on, until the further rotation of the gear 37 by the clockwork inactivates the hammer 27. More particularly, the alarm-repeat control mechanism includes a time-controlled latching device 45 (FIGS. 3 and 4) and a lifter element 46, pivoted at 47. Tapping of the push button 44, against the force of its spring 48, moves the lifter element 46, which engages lever 29 to raise the hammer 27 away from the core 26. The latching device 45 then retains the lifter element in its lever-lifting position for the predetermined alarm-repeat period. There is an operative connection between the latching device 45 and the clockwork which gradually drives the latching device from the position shown in FIG. 4 to the position shown in FIG. 3 by the end of the predetermined alarm-repeat time, causing the alarm to sound again. More particularly, the latching device 45 comprises an arcuate toothed element 49 pivoted at one end 51 to the lifter element 46 and engaged at its other end 52 by a spring 53 which serves to press the toothed lower portion 54 against the teeth of a gear 56 of the clockwork of the alarm clock. Normally, the teeth '7 of the lower portion 54 are clear of the gear 56 (as shown in FIG. 3) but when the right side of the pivoted lifter element 46 (as viewed in FIG. 4) is moved downwardly by the push button 44, these teeth are brought into engagement with the teeth of the gear 56. This keeps the lifter element 46 in its lever-lifting position until the gear 56 has been rotated sufficiently, by the clockwork to drive the teeth 57 away from the gear, thus releasing the lifter element.

In one form of this invention, the conventional alarm clock, described above, is modified by providing within the clock a device which inactivates the hammer which the sleepers hand is merely waved near the clock while the alarm is sounding. More particularly, the device is so arranged that the thrust of a hand near the clock critically alters the control grid bias on a thyratron 61, thus causing the thyratron to become conductive (or fire) and permitting current to flow through a solenoid 62 which then acts to return the hammer to its inoperative position, as will be described more fully below.

The thyratron 61 has the usual anode 63, grid 64 and cathode 66 and generally has a cathode-heating filament 67. Usually, the current for heating the filament should be supplied at a voltage considerably lower than that of the usual 120 volt power supply; accordingly the filament may be connected to the secondary winding of a suitable transformer. In one advantageous form of the invention I do not provide such a transformer as a separate element, but instead utilize the field coil 24 of the motor as the primary winding of the transformer and connect the filament to some turns 68 of wire wound around the same core 26. This reduces the cost of making the device and also saves the space which would be occupied by a separate transformer.

The usual alternating-current wiring to an electric outlet includes one wire that is grounded, and another wire that is hot. The circuit is such that the cathode 66 of the thyratron is connected to a conductor 69 adapted to be connected to the hot side 71 of the A.C. power supplied to the receptacle 23 when the plug 22 is properly inserted. This connection extends through a switch 72, 73, or alternatively through a test switch 74, 75. The anode 63 is electrically connected through the solenoid 62 to a conductor 76 adapted to be in electrical contact with the grounded side 77 of the power supply.

In the particular circuit shown in the drawing, the thyratron 61 is of the type having a negative control characteristic, e.g., a 2D2l thyratron in Which, at the applied anode-to-cathode voltage, the bias on the grid 64 must be a voltage more negative than the cathode to prevent firing of the thyratron. To set the grid bias at a level more negative than the firing voltage there is a DO supply and a voltage-dividing circuit. This circuit comprises a rectifier 78 and a filter such as capacitor 79 to provide DC voltage across a voltage divider comprising a resistor 81 and a potentiometer 82 in series. The grid is connected to the movable contact 83 of the potentiometer 82 through another resistor 84 which serves to limit the flow of grid current. Rectifier 78 is polarized to provide negative voltage on the grid, and the cathode 66 of the thyratron is connected to the positive end of the voltage divider. The resistance of resistor 81 is made quite large as compared to the total resistance of potentiometer 82 and there is therefore a relatively large voltage drop between the contact 83 and the grounded side of the power supply. In one form of the invention, the contact of the potentiometer is operatively attached to a control knob 85 which projects from the clock housing 12 to enable the user to preset the grid bias at a value which provides the sensitivity he desires, as will be explained more fully below.

Also electrically connected to the grid 64 is a capacitive element 86 of substantial area which serves to make the instantaneous voltage on the grid susceptible to change when the body having a large capacity to ground is brought into effective proximity to the clock. The capacitively sensitive element 86 is advantageously in the form of a conductive plate. The effect may be understood more clearly by reference to the capacitance 87, shown in dotted lines in FIG. 6, representing the human bodyto-ground capacitance. When this body capacitance is effectively coupled to the capacitively sensitive element 86, as when a person puts his hand near that element, there is established an AC. conductive path to ground which draws a signal current from the hot" side of the power supply. This introduces an additional voltage in the form of a sinusoidal wave. At each half cycle, during the positive peak, the voltage on the control grid 64 will thus be made more positive causing the tube to fire. Thus the control grid 64 constitutes the trigger electrode, previously mentioned, controlling firing of the thyratron.

There are, of course, other capacitances in the thyratron circuit, such as the small interelectrode capacitance between the cathode and the grid, which will have an efiect on the grid bias, but these are substantially unaffected by the previously described changes occasioned by the approach of the body to the element 86.

The switch 72, 73, for the supply of power to the thyratron circuit, has a fixed contact 73 and a movable contact 72 which is mounted, with the hammer 27 at the head end of the lever 29. The movable contact 72 is supported on the lever 29 by an electrically insulating member 87. One end 88 of the lifter element 46 is mechanically connected to the core 89 of solenoid 62 through a stifl? safety spring 91. The switch contacts 72 and 73 are preferably so positioned that they are brought together, during the previously described downward movement of the hammer 27, at the time the alarm is to be sounded. The thyratron circuit is therefore fully activated, with the thyratron in its non-conducting condition, at about the same time as the hammer begins to vibrate. If the awakened sleeper now brings his hand close to element 86, the thyratron becomes conducting and the solenoid 62 is energized. This pulls down the solenoid core 89 and the end 88 of the lifter element 46 and thus lifts the hammer away from the field core 26 and opens the switch 72, 73. This movement of the lifter element causes it to be held in position by the latching device 45 of the alarm-repeat control mechanism.

To prevent power line transients, on the anode-tocathode voltage, from accidentally causing the thyratron to fire when not coupled to body capacitance, the resistors 81 and 82 are so chosen that the D.C. grid bias is much more negative than the firing level. Thus, for a thyratron whose firing level is minus 3 volts at the applied anodeto-cathode voltage, I have found it advantageous to use a grid bias of minus 20 volts (which may be measured at the movable contact 83). To attain a large grid signal voltage, high enough to overcome this large grid bias, from the coupling of the circuit to body capacitance, I have found it advantageous to employ a large value for the resistance 84. The grid is thus connected to the energized side of the power source through an impedance that is of the same order of magnitude as the impedance resulting from the interposition of the humand hand. This gives a considerable AC. voltage drop from cathode to grid in the previously described A.C. circuit which runs to ground from the hot side of the power line through resistor 84, capacitively sensitive element 86 and body capacitance 87. In one example, the resistor 84 has a value of 20 megohms, the resistor 81 has a value of 33,000 ohms and the potentiometer 82 has a resistance of 5,000 ohms.

The possible effects of transients in accidentally causing the thyratron to fire are also minimized by the fact that the anode-to-cathode voltage is not applied until be moved to obtain increased about the same time as the alarm is sounded, as previously described. The cathode of the thyratron is, however, already in its heated condition at this time thus eliminating the variations which occur during the warm-up period. In the preferred form, as already described, the cathode is kept heated continuously, and suitable vents for removing the hot air are advantageously provided, as in the rear of the clock. The switching arrangement may be altered so that the cathode heater is turned on (as by a switch controlled by the position of the alarm cam) only a short time before the switch 72, 73 is closed (that time being suificient, however, to thoroughly heat the cathode) and the heater is then turned off when the alarm cam pushes the apertured wheel at the close of the alarm period.

The reliability of the circuit is also enhanced by the fact that the thyratron is within the alternating magnetic field of the motor 16 (e.g. about 4 inch of the field core 26). This provides a constant ionizing field for the gas Within the thyratron tube, overcoming the characteristic low reliability of many thyratrons in the darkness prevailing inside the clock, particularly when the room is dark. It also makes the thyratron less sensitive to, and substantially independent of, stray ionizing influences.

A test switch 74, 75, operable from a knob 92 projecting from the housing 11, is provided to enable the user to adjust the sensitivity of the thyratron circuit to the level he desires for any particular positions of the clock. When the test switch 74, 75 is closed, power is supplied to the thyratron circuit. The user, lying in bed near the clock, can close the switch, withdraw his hand, and then bring it closer to the clock until he hears the click resulting from the impact of the core 89 on the base 93 of the solenoid 62 when the thyratron fires. He can withdraw his hand and repeat the process any number of times, hearing the click each time, since the thyratron, being connected across an A.C. cathode-to-anode power supply, will automatically become non-conducting when the hand is withdrawn, provided potentiometer 82 has been set to give a non-firing grid bias. The user may find that, owing to a previous setting of the potentiometer contact, the circuit is so sensitive that his normal movements during sleep would bring him to a position where his body would provide sufiicient capacitance to cause the thyratron to fire, when its circuit is powered, even without a wave of the hand. In such a case the user need merely adjust the potentiometer, by means of its knob 85, to decrease the sensitivity by moving his hand close to the clock and listening for the click. Again, the user may find that a previous potentiometer setting has made the circuit so insensitive that his hand must almost touch the clock in order to prdouce the click. He need merely move the potentiometer knob to increase the sensitivity and repeat the test, until the desired sensitivity is attained, e.g. until the device is sensitive to the approach of the hand to a point two inches from the outside of the clock. In each case, once the potentiometer has been properly set, it is preferable to open the test switch '74, 75. However, it is unnecessary to open the test switch during the adjusting process. The knob 92, or the clock housing near the knob, is advantageously marked to indicate to the user the directions in which the knob should and decreased sensitivity, respectively. If the potentiometer knob is omitted the user can employ the same testing method as described above, but altering the position of the clock rather than its sensitivity to make the desired adjustment.

It will be understood that when the parts are in the position shown in FIG. 3, the core 89 projects partially out of the solenoid 62, and the bottom of the core is spaced above the base of the solenoid. Energization of the solenoid then brings the core to its lowest position. The stiff spring 91 acts as a shock absorber to prevent damage to the parts, particularly to the lifter element 46 and lever 29, during these movements.

A suitable A.C. bypass such as a rectifier 94 may be provided, in parallel with the solenoid 62, to reduce or eliminate chattering of the core 89 in the solenoid when the device is being tested. So long as the grid is made sufficiently positive to cause firing, the thyratron will shut ofl? on one half-cycle of the A.C. supply and restart on the next half-cycle continually. The rectifier 94 serves to bypass the A.C. component of the output current of the thyratron so that the core 89 has less tendency to move up and down in response to these variations.

As previously stated, the capacitively sensitive element 86 is advantageously in the form of a conductive plate. In practice a square plate, 25 square inches in area, attached to the base of the clock an inch below the clockwork, has proved to be very suitable. In that position there is a greater sensitivity to capacitive changes occasioned by the approach of the users hand, in that there is relatively little capacitive coupling between the capacitively sensitive element and the clockwork of the clock. However, good results have been obtained, particularly when the values of the resistances are chosen as indicated above, by using as the capacitively sensitive element a piece of aluminum foil placed just behind the clock face 13 and flush therewith. When the face itself is of metal it may be employed as the capacitively sensitive element. It will be appreciated that the capacitively sensitive element 86 may be situated between, and protected by, electrical insulating elements or insulating coatings, and may be located on the top or sides of the clock instead of, or as well as, at the bottom. The capacitively sensitive element may also be a plate separate from the clock, and connnected to the grid by means of a flexible conductor. Such an arrangement is, however, less preferable than the form previously described in which the clock, with the plate, is a unitary self-contained device.

It will be understood that, in the form illustrated, the plu'g' 2 2 must be inserted in the correct way into the receptacle 23 so that the thyratron anode 63 is electrically connected to the grounded side of the power line. To facilitate this, the plug is advantageously suitably marked, as by making the prongs of different sizes or placing appropriate indicia opposite one prong or the other. In any event, the user can make a simple preliminary test to determine whether the plug has been inserted correctly. One such test involves closing the test switch 74, 75, setting the potentiometer knob 92 by hand until the click is heard, removing the hand and then bringing the hand close to the clock. If neither the removal of the hand nor its reapproach to the clock then have any effect, the plug should be reversed and the knob 92 reset to the desired sensitivity.

It will be apparent that various embodiments of. the invention may be devised by those skilled in the art, utilizing the novel features in the device specifically described above. Consequently, the invention should be construed broadly, in accordance with its full spirit and scope.

What is claimed is:

1. An electric clock having alarm means and having an alternating current motor, connections for said motor to an alternating current supply line that characteristically has a hot side and a grounded side, normally passive means including a control electrode responsive to activating signals for deactivating said alarm rneans, and means including an impedance connected in a circuit between said control electrode and said hot side of the alternating supply line via one of said connections of said motor for developing activating signals for said normally passive means, said last-named means including a capacitive element physically connected to said clock and coupled to said control electrode for coupling said impedance to the grounded side of the alternating current supply line 7 via human body capacitance upon approach of a human hand to the clock.

2. An alarm clock as in claim 1 wherein said clock has a casing to which said capacitive element is secured and wherein said means including said capacitive element for developing said activating signals is rendered operative by the approach of a human hand to a zone in the atmosphere around said clock and casing about two inches outside said casing.

3. An electric alarm clock as in claim 1 including a normally open switch closable approximately at the start of alarm operation for rendering operable the coupled capacitive element and normally passive means, whereby a signal on said trigger electrode substantially earlier than the start of alarm operation will be ineffective to bring the time-controlled alarm to its inactivated condition.

4. An electric alarm clock as in claim 3 and including manually operable switch means operable independently of the alarm for rendering operable the coupled capacitive element and normally passive means, and manually operable means for adjusting the sensitivity of the coupled capacitive element and normally passive means when in said operable condition whereby the user can test the sensitivity of the clock to the alarm-inactivating effect of human body capacity without sounding the alarm.

5. An electric alarm clock as in claim 1 and including solenoid having an alarm-inactivating core and an alternating current bypass in parallel wit-h the solenoid to reduce chattering of the core in the solenoid when the alarm-inactivating means is being tested.

6. An alarm clock as set forth in claim 1, said trigger electrode having a predetermined firing level and said responsive means including means providing an antifiring bias on said trigger electrode greatly in excess of said firing level.

7. An alarm clock as set forth'in claim 1, said trigger electrode being connected to the energized side of said power source through an impedance that is of the same order of magnitude as that of the capacitive element when in operative cooperation with the human hand.

References Cited by the Examiner UNITED STATES PATENTS 1/1936 Ostermeier et al. 328-5 3/1963 Atkins et al. 5050

Claims (1)

1. AN ELECTRIC CLOCK HAVING ALARM MEANS AND HAVING AN ALTERNATING CURRENT MOTOR, CONNECTIONS FOR SAID MOTOR TO AN ALTERNATING CURRENT SUPPLY LINE THAT CHARACTERISTICALLY HAS A "HOT" SIDE AND A GROUNDED SIDE, NORMALLY PASSIVE MEANS INCLUDING A CONTROL ELECTRODE RESPONSIVE TO ACTIVATING SIGNALS FOR DEACTIVATING SAID ALARM MEANS, AND MEANS INCLUDING AN IMPEDANCE CONNECTED IN A CIRCUIT BETWEEN SAID CONTROL ELECTRODE AND SAID "HOT" SIDE OF THE ALTERNATING SUPPLY LINE VIA ONE OF SAID CONNECTIONS OF SAID MOTOR FOR DEVELOPING ACTIVATING SIGNALS FOR SAID NORMALLY PASSIVE MEANS, SAID LAST-NAMED MEANS INCLUDING A CAPACITIVE ELEMENT PHYSICALLY CONNECTED TO SAID CLOCK AND COUPLED TO SAID CONTROL ELECTRODE FOR COUPLING SAID IMPEDANCE TO THE GROUNDED SIDE OF THE ALTERNATING CURRENT SUPPLY LINE VIA HUMAN BODY CAPACITANCE UPON APPROACH OF A HUMAN HAND TO THE CLOCK.

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