US3780522A

US3780522A - Alarm timepiece

Info

Publication number: US3780522A
Application number: US00255819A
Authority: US
Inventors: M Yoshida
Original assignee: Citizen Watch Co Ltd
Current assignee: Citizen Watch Co Ltd
Priority date: 1971-06-05
Filing date: 1972-05-22
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25
Also published as: CH559933B5; CH559933A; CH825972A4; DE2226522A1; GB1382704A; JPS487067U

Abstract

A small alarm timepiece having a timepiece movement, an electrically operating buzzer as an acoustic alarm signal delivery means, a battery detachably mounted on the timepiece movement for energizing said buzzer for its operation, and an alarm switch for on-off control of the operation of the buzzer. This alarm switch is operatively connected with the movement so as to be closed at a preset time point and to remain closed for a certain predetermined operation period. The drive circuit for the buzzer is designed as a free-running oscillator having an oscillator transistor. In addition to the alarm switch, there is provided a switching transistor operatively connected with the first mentioned transistor. There is provided a CR-time limiting circuit operatively connected with the switching transistor for control thereof. In this way, the operating period of the buzzer is limited to only a small fraction of the closure period of the alarm switch which is adapted for being mechanically closed at the preset time by the action of an alarm control mechanism fitted to the timepiece movement. In this way, the power consumption of the electronic alarm can be minimized.

Description

United States Patent [1 1 Yoshida 51 Dec. 25, 1973 1 ALARM TIMEPIECE [75] Inventor: Makoto Yoshida, Tokorozawa,

Japan 22 Filed: May2i, 1972 211 A 1.No.=2ss,s1b

[30] Foreign Application Priority Data June 5, 1971 Japan 46/47337 [52] US. Cl. 58/38, 58/575 [51] Int. Cl. G040 21/34, G04b 23/12 [58] Field of Search 58/38, 57.5

[ 5 6 References Cited UNITED STATES PATENTS 3,638,418 2/1972 Spadini 58/57.5 3,462,943 8/1969 Spadini 58/575 3,505,806 4/1970 Schwiegne et al. 58/38 3,577,876 5/1971 Spadini 53/575 3,589,123 6/1971 Flaig et al. 58/38 3,689,919 9/1972 Ganter et al r. 58/38 X Primary Examiner-Gerirge H. Miller, Jr. Attorney-John C. Holman et al.

57 ABSTRACT A small alarm timepiece having a timepiece movement, an electrically operating buzzer as an acoustic alarm signal delivery means, a battery detachably mounted on the timepiece movement for energizing said buzzer for its operation, and an alarm switch for on-off control of the operation of the buzzer. This alarm switch is operatively connected with the movement so as to be closed at a preset time point and to remain closed for a certain predetermined operation period. The drive circuit for the buzzer is designed as a free-running oscillator having an oscillator transistor, In addition to the alarm switch, there is provided a switching transistor operatively connected with the first mentioned transistor. There is provided a CR- time limiting circuit operatively connected with the switching transistor for control thereof. In this way, the operating period of the buzzer is limited to only a small fraction of the closure period of the alarm switch which is adapted for being mechanically closed at the preset time by the action of an alarm control mechanism fitted to the timepiece movement. ln this way, the power consumption of the electronic alarm can be minimized.

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27a 27b 27C PATENIEDnmzs ms SHEETZUF'Z F I G. 4

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, 1 ALARM TIMEPIECE This invention relates toimprovements in and relating to a small electronic timepiece, especially an electronic watch, which is fitted with an electronically driven alarm from battery means contained in said watch and adapted to drive the electronically operatable watch movement.

In the case of a mechanical watch, having its mechanical power source, such as power spring or the like and fitted with an alarm of the mechanical driven type, the power spring must be energized each time a desired alarm time is to be established, so as to replenish in advance the power consumption to be made during the alarm period. This is caused by the fact that the conventional power spring has a relatively small power capacity which is naturally of most concern on the one hand, and on the other hand the alarm mechanism will operate, each time the alarm is sounded, for a relatively long period, such as ten minutes or even longer until it is brought to a dead stop, Thus, when a user of the alarm watch does not manipulate a certain stop means for stopping the working of the once operated alarm, the alarming operation may continue until the power spring has been brought to its completely rewound state. This period may generally xtend only for five minutes or so.

With modern development of electronics as applied rapidly to and in the field of timepiece movement engineering, it is known to a skilled person in the art to employ-a battery as the power source of a watch alarm for obviating the troublesome alarm energy replenishment necessary each time that the alarm time setting job is performed. It is, however, highly desirable to control the electrical alarm switch adapted for on-off control of the electrically driven alarm mechanism by a wheel means which rotates once per 12 or 24 hours on account of its highly simple'structure and easy setting convenience as commonly provided by use of the conventional alarm mechanisms. If the electric alarm should operate for as long as 10 minutes or so, with the electric switch means kept in its continued conducting state, the power battery would be consumed within a relatively short period which must naturally be avoided from the view point of power economy.

The main reason why the electronic watch fitted with an electronic alarm has no't'yet been commercialized resides in the aforementioned drawback. For instance,

when the electronic alarm, such as electronic buuer,

is brought into operation once per 12 or 24 hours for 10 minutes or so without manipulation of the alarm stop means, the power battery must be replaced by a new one within a half yearior so. When the timepiece movement is of the electronically driven type and the power battery is common to both, the durable life of the battery may be still further shortened to, for instance, 5 months or so. When the alarm has been designed to provide for settability to several destined alarm time points, the aforementioned drawback has made it difficult to realize the last mentioned alarm mechanism advanced so far.

An object of the present invention is to provide an electronically operated alarm mechanism devoid of the, aforementioned conventional drawbacks and highly adapted for use in a small timepiece, especially an electronic watch, which is small in its design and arrangement, and capable of usage for an extended time period without exchange of the power battery.

For the realization of the aforementioned object of the invention, the invention starts in its broadest aspect from such a combination of: a timepiece movement; an acoustic alarm means arranged to be driven through an electronic drive circuit means from a battery means; and one or more alarm switches adapted for bringing said drive circuit means into operating conditions at least at a certain predetermined time. The characterizing feature of the present invention resides broadly in such that the said drive circuit for the drive of the acoustic alarm means comprises in combination a freerunning transistored oscillator which includes a oscillator transistor and a switching transistor electrically connected to the base electrode thereof, and a CR-time limiting circuit operatively connected with said switching transistor for control of the operation thereof.

In such a device, when the alarm switch is turned on, then the switching transistor is turned on or off, as the case may be, upon lapse of a predetermined time period as determined by the time constant of the CR-time limiting circuit. With the operational conversion of the switching transistor from on to off or in the reverse direction in the above sense, the oscillator circuit is deprived of the operationalcurrent and a small amount of dark current will continue to flow through the transistor until the alarm switch or switches has been turned off. At this instance, the acoustic alarm terminates its operation. Therefore, it will be seen that the power consumption from the instance where the operational termination of the acoustic alarm has taken place to the point where the alarm switch turns off may be neglegibly small and thus highly economical.

These and further objects, features and advantages of the invention will become more apparent when the following detailed description of the invention is read with reference to the accompanying drawings illustrative of several preferred embodiments of the invention.

In the drawings:

FIG. 1 is an axial section of a small timepiece fitted with an electronic alarm device embodying the principles of the invention wherein, however, the drive circuit block for the acoustic alarm is sectioned only partially and the regular gear train and the battery block contained in the movement are shown in their elevation.

FIG. 2 is a bottom view of the timepiece movement shown in FIG. 1, showing, however, substantially exclusively the alarm mechanism, other related conventional parts having been omitted from the drawing for better and more clear understanding of the invention.

FIG. 3 is a plan view of the timepiece movement shown in FIGS. 1 and 2, yet being shown on a somewhat reduced scale relative to that employed in FIGS. 1 and 2, wherein, however, several minor and conventional parts are not shown only for simplicity of the drawing.

FIG. 4 is a connection diagram of an embodiment of the device circuit for the acoustic alarm employed in the invention.

Referring now to FIGS. 1-4, the first embodiment will be described hereinbelow in detail.

Numeral 1 generally denotes a watch movement in its broadest sense and comprises a conventional pillar plate 2, appearing only partially and mounting several main working parts, as will become more clear as the description proceeds.

Numeral 3 represents a mercury battery of known structure and detachably mounted within said movement 1. In the present'embodiment, this battery 3 is adapted to feed an electronically operated timepiece movement and a buzzer with current, as will be more specifically described hereinafter.

A battery mount 4 made of an insulating material and fixed with said pillar plate 2 mounts the battery block 3 in position, a pressure spring 5 detachably attached by means of set screws 5a and.5b to the plate 2 holding the battery block in position from upper of FIG. 1 with a slight resilient pressure applied thereto.

Numeral 6 represents only schematically an electronic drive circuit of conventional structure and molded into a block with a synthetic resin and detachably attached to pillar plate 2 by means of set

screws

6a, 6b and 60. This drive circuit is adapted for driving electro-dynamically a conventional time base oscillator, preferably in the form of a balance wheel motor, a turning fork, a turning lead or the like, as commonly known per se. The drive circuit is electrically connected through the plate 2 and lead wire means, not shown, to the battery 3, as known per se.

Numeral 8 represents a main working parts block including the conventional watch gear train and comprising a balance wheel 8a which is driven electromagnetically from said electronic drive circuit 6, said gear train, although not shown specifically by virtue of its very popularity, being mounted by and between the plate 2 and bridges 8e;8f which are fixedly attached thereto by means of a plurality of set screws 8b;8c and 8d. It should be mentioned at this stage that the term block" in this case is used only for convenience so as to discriminate the gear trainas a whole from other working parts of the watch and it does not constitute a practical block.

Numeral 9 represents an alarm oscillator circuit block comprising transistor(s), condenser(s), resistors and the like which constitute an electronic oscillator and compacted into a molded block 9a by a synthetic resin such as an epoxy base resin, and a transformer 9b electrically connected with said oscillator and with a piezoelectric or electro-strictive element 25. This transformer 9b serves for elevating the output from the oscillator in its voltage so asto adapt for oscillation of theelement 25 as will become more apparent as the description proceeds. This circuit block 9 is fixedly, yet easily detachably attached to the plate 2 by means of several set screws 9c;9d.

Numeral 10 denotes a conventional time-indicating dial bearing on its outer surface with known timeindicating symbols although not shown, for the demonstration of time by cooperation with time-indicating hands l4, l5 and 16. This dial 10 is detachably mounted on the plate 2, although the attaching means have been omitted from the drawing only for simplicity and convenience. It should be noted, however, that a conductive strip 10a is provided in a concentric ring on the inside surface of the dial 10, and preferably, by the print circuit technique.

Battery mount plate 4 is formed with a perforation 4b in which a U-shaped contact spring 4a is kept in position in somewhat projecting manner. In the assembled position shown, this contact spring 4a serves as conducting means between said battery 3 and conductive strip 10a.

Numeral 11 denotes a conventional cannon wheel and a conventional unlocking wheel 12 is rotatably mounted thereon. An unlocking spring 13 is provided as shown, especially in FIGS. 1 and 2, the root end of this spring 13 is fixedly mounted on a terminal 92 of said oscillator circuit block 9 by means of a set screw 13a. The free end 13b of spring 13 is kept in pressure contact with the upper surface of the wheel 11, so as to urge resiliently the latter to move axially downwards when seen in FIG. 1. A projection or contact portion 13c is formed on the spring 13 at an intermediate point between the ends thereof, thus providing a possibility to establish an electrical cooperation with conductive strip 10a on the dial 10'.

Cannon wheel 11 is formed with three projections 11a having mutually different radial lengths measured from the center of the wheel 11. Only for simplicity, however, these projections llaare represented as if they are single in FIG. 1. In a corresponding way, unlocking wheel 12 is formed with three different perforations 12a (refer especially FIG. 2).

Numerals

40, 41 and 42 represent a series of successively engaging intermediate gears of which the last one 42 is directly attached to the innermost end of an unlocking stem 43. This stem 43 is manually rotatable as in the conventional winding stem 45 only partially shown, these stems 43 and 45 being mounted rotatably in the pillar plate 2, although the bearing means have been omitted from the drawing by their very popularity. As seen from FIG. 2, manual torque can be transmitted from the unlocking stern applied occasionally thereto, through

gears

42, 41 and 40 to unlocking wheel 12 for setting the latter to a desired alarm time. For indication of the alarm time, the unlocking wheel 12 is fitted with an alarm hand 14. This hand 14 is press-fit on the boss of the wheel 12.

Numeral 44 represents an intermediate gear which is designed and arranged to transmit driving torque from the regular time-keeping gear train to the cannon wheel 11. As commonly known, the cannon wheel 11 performs a complete revolution per 12 hours by receiving motion from the gear train of the watch. When the alarm time comes, the projections 11a on the wheel 11 are brought into engagement with corresponding and mating perforations 12a on the wheel 12, thereby the former wheel 11 being urged to move downwards in FIG. 1 and nearer towards the latter wheel 12, so as to establish an electrical connection between the contact portion on spring contact 13 and the conductive strip 10a on dial 10.

Hour hand 15 is press-fit on the boss of cannon wheel 11 as conventionally. Minute hand 16 is attached on top of a conventional cannon pinion 17.

Numeral 18 represents a case central body which mounts detachably a transparent plastic cover 19 used in this specific embodiment in place of a crystal, a ringshaped tension spring 19a urging the cover from inside to expand resiliently outwards, so as to establish a tight and sealed connection between the cover and the case center body.

A ring-shaped movement positioner 20 is positioned along its substantial peripheral length between plate 2 and case center body 18. A sealing ring 21 is inserted between the case central body 18, and a membrane carrier 22 having a ring web projection 220 on which the periphery of an oscillatory membrane 24 is fixedly attached by means of adhesive. The carrier 22 is formed with an inwardly projecting arm 22b and provided with an insulator sleeve 23a which holds firmly a combined stationary contact and terminals 23. On the inside surface of the membrane 24, a piezoelectric or electro-strictive element 25 is firmly attached by glueing or the like conventional attaching means, conductive leads 26 connecting electrically the contact and terminals 23 with the element 25.

The molded alarm oscillator circuit block 9 is provided at its output side with conductive spring arms 9f which are normally kept in pressure and conductive contact with the members 23 when the block 9 and membrane carrier 22 have been assembled together in position as seen clearly from FIG. 1. The root ends of said spring arms 9f are embedded rigidly in the mass of the molded block 9.

Numeral 27 denotes a back cover which is formed with .a number of projections 27a over its substantially whole area so as to prevent a tight contact with the wearers skin, while the remaining base area 27b is formed with a number of perforations 27c for releasing acoustic alarming signals from inside of the watch into the open atmosphere.

At the outside periphery, the back cover 27 is formed with several recesses 27d for receiving operating ends of a turning tool. Further, the back cover 27 is formed on its peripheral surface with male screw threads 27e adapted for engagement with mating female screw threads 180 formed on the case central body 18. For attachment of the back cover 27, it is screwed from upper into the body 18 by use of the turning tool.

It will be clear from the foregoing that the interior space of the watch as defined by membrane 24, carrier 22 thereof, sealing ring 21, case central body 18 and transparent and plastic front cover 19 is kept effectively in a sealed condition for prevention of an invasion of moisture from outside into inside of the watch.

In FIG. 4, an embodiment of the drive circuit for the drive of a buzzer 50, said circuit basically comprises a membrane 24 and a piezoelectric or electro-stritive element 25.

Numeral 51 represents an alarm switch comprising unlocking spring 13 and conductive strip a which are specifically shown in FIG; 1.

Blocking oscillator transistor 52, switching transistor 53 adapted for on-off control of the operation of the former transistor 52 and timer transistor 54 adapted for on-off control of the operation of the latter transistor 53 so as to determine the operational duration period of buzzer 50, are seen in FIG. 4 and connected one after another as shown.

The base electrode of the transistor 54 is connected through source conductor 55 to the positive side of a source battery 64, on the one hand, said source conductor 55 being inserted with resistor 56 and alarm switch 51, while said base electrode is connected to earth through a condenser 57. Resistor 56 and condenser 57 constitute in combination a time-limiting circuit which operates in such way that with the electrical charge accumulated in the condenser 57, the base potential of transistor 54 will vary. The collector electrode of said transistor 54 is connected through collector resistor 58 to source conductor and at the same time directly coupled with the base electrode of switching transistor 53. The emitter electrode of transistor 54 is directly earthed. The collector electrode of switching transistor 53 is connected through resistor 60 to source conductor 55, while the emitter electrode of the same is connected to earth through condenser 62, and at the same time with one end of the primary winding of a blocking oscillator transformer 63, the opposite end of said winding being connected with the base electrode of transistor 52.

The collector electrode of transistor 52 is connected with one end of secondary winding of said transformer 63, while the emitter electrode of the same transistor is connected directly to earth.

A central tap on the secondary winding of the transformer 63 is connected to source conductor 55, while the buzzer 50 is connected across the secondary winding. The transformer 63 acts as a voltage booster, so as to drive the element 25 optimumly. As seen, resistor 60, condenser 62, transformer 63 and transistor 52 constitute in combination a blocking oscillator circuit shown by a dotted-chain line block 65.

Circuit elements

56, 57, 58 and 54 constitute in combination a CR-time-limiting circuit shown by a chain-dotted line block 66.

The operation of the firstembodiment of the watch alarm according to the first embodiment of the present invention will be described in detail.

The unlocking wheel 12 is set to a certain selected time point by mainpulating the auxiliary winding stem 13 as was briefly described hereinbefore.

When the alarming time comes, projections 11a on the wheel llare brought into engagement with corresponding perforations 12a in the wheel 12 so that the former wheel 11 is urged to move downwards in FIG. 1 under the action of unlocking spring 13 and the intermediate contact portion l3c thereof is brought into pressure contact with the conductive strip 10a, thereby the unlocking switch 51 being turned to on. In this way, current is supplied from battery 3 to alarm oscillator circuit 9. More specifically, a circuit is closed through battery 3, contact spring 4a, conductive strip 10a on dial 10, unlocking spring 13, oscillator circuit 9 and pillar plate 2.

When the oscillator circuit 9 starts to oscillate in this way at .a certain constant frequency, preferably selected between 1,000 and 4,000 cycles per second, the oscillatory output voltage therefrom is conveyed through the elevating transformer 9b to the element 25 which is thus kept in oscillation together with its carrying membrane 24. By the oscillative movement of the membrane 24, a corresponding acoustic signal is generated and will be delivered from the interior of the watch casing comprising the members l8, l9 and 27 into the open atmosphere through the perforations 27c of the back cover 27.

At this stage, the circuit shown in FIG. 4 will act in the following way.

When the alarm switch 51 turns on in the aforementioned way, the base potential at the transistor 54 will rise up in accordance with the time constant as determined by the specifically selected combination of resistor 56 and condenser 57. During this potential rising-up period until the base voltage attains at the conducting voltage for the transistor 54, the latter is held in its offcondition.

During this period, the collector voltage at transistor 54 is kept substantially at the source voltage level, thereby providing a proper base current to transistor 53 for operation thereof. Thus, the transistor 53 is in its conducting state and thus provides through its collector a base current to transistor 52. At this stage, the impedance at the collector-emitter passage becomes naturally enough low practically to establish the blocking oscillator 65. In this way, the buzzer 50 operates to deliver acoustic alarm signal.

Upon lapse of a certain predetermined time period as determined by the time constant provided by the specifically selected combination of resistor 56 and condenser 57, the base potential of transistor 54 reaches its threshold voltage, thus the transistor becoming on, while the collector electrode thereof has substantially nil potential. Since at this stage, the base potential of transistor 53 becomes substantially nil, it becomes off. Therefore, the blocking oscillator can not oscillate and the operation of buzzer 50 will cease.

In this way, the buzzer'50 will continue to operate for a predetermined period depending upon the CR-time constant as determined by the combination of resistor 56 and condenser 57, as referred to hereinbefore, upon the closure of alarm switch 51, and then it terminates its operation automatically.

Upon the cease of operation of the buzzer 50, the transistor 54 only will be kept in its operating condition until the alarm switch 51 is opened. But, the current consumption during this stage can be made negligibly small by selecting the resistances at

resistors

56 and 58 to relatively large values.

In a preferred practical embodiment, the main circuit constants are selected as'follows:

resistor 56 5 megohms;

resistor 58 l megohm;

resistor 60 I kiloohms;

condenser 57 l microfarad;

condenser 62 l nanofarad;

winding ratio of transformer 63 l0; duration term of operation of buzzer'50 about seconds; operating frequency of blocking oscillator 65 LOGO-4,000 Hz;

The above specified duration time, about 5 seconds, buzzer 50 is enough for the desired alarming purpose, which is naturally very short in comparison with the regularly employed conventional value such as minutes. In this specific embodiment, the current consumption upon automatic cease of buzzer operation amounts to 2-3 microamperes which is very small in comparison with that for the buzzer operation, amounting generally to l-2 miliamperes.

When considering such case that the timepiece movement is of the electronically driven type and thus, the source battery is designed and arranged to be common to the movement and the alarm, the daily power consumption rate will amount at the highest to 7 microampere-hours under the assumption that the buzzer operates twice per day. When further assuming that the electronic movement operates with 8 microamperes, then the daily power consumption will amount to 0.192 miliampere-hours and if the capacity of the source battery be 100 miliampere-hours, then the overall life of the battery used for the said both purposes will be:

100/ 0.007 0.192) E 500 days.

Thus, the electronic timepiece with the electronic alarm built in accordance with the present invention will operate for 500 days.

On the other hand, when the electronic watch is designed to operate. for a complete year with the source battery having the same capacity as above, how many times, the electronic alarm can operate per day? Since 69 miliampere-hours must be consumed for the continuous operation of the electronic movement for a complete year round, the remaining power available for the operation of the alarm will be 30 miliamperehours. With the power consumption of the alarm being 3.5 microampere-hours for an alarming operation, 8 500 times of alarming operations can be assured with the above mentioned energy available therefor, and thus, the alarm can operate 24 times per day which is sufficient for the destined alarm service.

When further assuming that the alarm must continu' ously operate once for 10 minutes in place of 5 seconds and a current of 3 miliamperes should flow during the prolonged service period, only times of alarming operation or so could be performed. Thus, in such case, alarming operation once per two or three days can only be assured and a commercially acceptable electronic alarm watch could not be provided.

In a modified arrangement shown in FIG. 5, the alarm switch equally denoted with the same reference numeral 51 as before is shifted to a position along the source conductor 55 which lies between the blocking oscillator 65 and the time-limiting circuit block 66.

For convenience and easy comparison, same reference numerals are used for same or similar circuit parts employed in the present modification as those shown and described in and with reference to FIG. 4.

With the switch 51 closed, current will flow from battery source 64 through source conductor 55, secondary winding of transformer 63 and collector-emitter passage of transistor 52 to earth, for actuation of the buzzer 50 as in the aforementioned way. Since, at the present stage, the impedance between source line 55 and earth which provides the above current passage route, practically variable contact pressure at the switch 51 when the latter is arranged as shown in FIG. 4 will affect appreciably the emitter-collector voltage of the same transistor, thus influencing the alarm signal delivered from the buzzer, generally in its reducing sense. Thus, a certain affect upon the buzzer signal by the variable contact at the switch 51 when it is arranged as shown in FIG. 4 may frequently be encountered. In the modified arrangement shown in FIG. 5, since the resistance values at

resistors

56 and 58 have been selected to have rather larger values and due to the modified positional arrangement of the switch 51, almost any influence upon the time constant of the time- Iimiting circuit comprising

several circuit elements

54, 56, 57 and 58 can not be encountered even by the variable contact pressure at the switch 51.

In addition, the aforementioned drawback of varia' tion in the impedance of the emitter-collector passage of the transistor 52, through which the main drive current for the actuation of the buzzer, can also be remedied.

In this way, the buzzer can operate in a highly stabilized way and at a substantially constant signaling level.

In a still further modified arrangement of the buzzer drive circuit shown in FIG. 6, numerals 151; 153; 155; 156; 157; 163; 164 and 165 are similar to those denoted respectively with numerals 50; 51; 53; 55; 56; 57; 63; 64 and 65 in the foregoing embodiments.

The alarm switch 151 provided in the source conductor 155 between bias resistor and transformer 163. This positional arrangement of the alarm switch is for the same purpose as mentioned in the foregoing with reference to FlG. 5.

In the present modification, transistor 153 is so designed and arranged that it may take over the function of the timer transistor 54 in addition to that of a switching transister. The base of this transistor is connected through resistor 156 to source conductor 155 and through condenser 157 to earth. The collector is connected through conductorll to the base of a transistor 171 which is positioned substantially similarly to that'shown at 53 in FIG. 4 or 5. The emitter of transistor 153 is directly earthed.

Transistor 171 constitutes in cooperation with a transistor 170, an astable or free-running multivibrator, having several auxiliary circuit elements 172; 173; 174; 175 and 176 which are connected one after another as shown.

When a predeterminedly set time point comes, alarm switch 151 is closed and either

transistor

170 or 171 is turned on, while the remainder will become simultaneously off and vice versa, being performed as known per se in a repeated manner. This repeatedly performed on-off operation will extend for a certain predetermined period, as determined by specifically selected circuit constants of the elements 172; 173; 174 and 175.

With the transistor 171 turned to on, current will flow through the transformer 163, so as to drive the buzzer 150. r

For a certain short period upon closure of the alarm I switch 151, the base potential at the transistor 153 will continue to rise up in accordance with the specific time constant as determined by the respective values of re sistor 156 and condenser 157. During the term until attainment of the base potential at the conductive voltage of transistor 153, the latter maintains its off state. Thus, although the multivibrator circuit 165 will continue to oscillate, the transistor 153' turns on when the base voltage becomes equal to the conductive thereof.

Thus, currentwill flow through the resistor 174 and the collector-emitter passage of transistor 153 and the base potential of transistor 171 will decrease and this transistor will not become on. Therefore, the operation of the circuit 165 will cease.

Although current will continue to flow through resistor 156; base-emitter passage of transistor 153, and through resistor 175; base-emitter passage of transistor 170; and further through resistor 176; and collectoremitter passage of transistor 170, the overall power consumption rate at this stage may be neglegibly small, by virtue of the resistance values at 156; 174; 175 and 176 selected to relatively small values.

In the case of the modification shown in FIG. 6, main circuit elements have been selected to have respective circuit constants as follows:

resistors

174 and 176 each 300 kiloohms;

resistor 175 100-300 kiloohms;

condensers

172 and 173 each 2,000 picofarads;

resistor 156 2 megohms;

condenser 157 2 microfarads;

With use of these constants, the working period of the buzzer extends for about 4 seconds. The oscillation frequency: l,O00-4,000 Hz; buzzer-operating current: about 2 miliamperes; Current consumption rate after automatic cease of operation of the buzzer is about 1 microampere.

With use of a conventionally used battery, the alarm watch can operate longer than one year, as was true in the foregoing embodiments, so far as the alarm is not too much frequently actuated.

if the alarm switch is kept in its astably contacting state, a so-called chattering phenomenon will be invited. In such case, transistor 153 will unexpedly be turned from on to off. For avoiding this drawback, provision of a condenser shown with dotted lines at 177, for instance, of 10 microfarads, may preferably be made.

As was explained hereinbefore, about 7,0009,000 alarming operations can be assured over a complete year round, or more specifically 20-30 times of alarming operation per day, canbe assured, even with use of a mercury battery of the normal capacity as is being used for the drive of the electronic watch movement, and thus a highly convenient and efficient alarm watch can be provided when obeying the novel principles of the invention, as was disclosed in the foregoing specification and to be specifically claimed in the appended claims.

As a result, an advanced electronic alarm for small timepieces, especially electronic watches, where a plurality of alarming times are preset at a time. In this case, a corresponding number of alarm switches must be proved as known per se. These switches are operated successively. Upon successive arrival of these preset time points, the buzzer is operated in succession, as may be well supposed from the foregoing description.

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:

1. In an alarm timepiece comprising a timepiece movement; acoustic generating means mounted on said movement for generating an acoustic alarm signal; an electronic drive circuit mounted on said movementand having a detachable battery for providing current to said drive circuit; at least one alarm switch operatively connected with said movement and said drive circuit so that upon closure of same at a preset time said current flows through said drive circuit to initiate operation of same and cause said generating means to generate the acoustic alarm signal, the improvement wherein said generating means comprises a piezoelectric oscillator attached to a vibratable membrane mounted in said timepiece, said electronic drive circuit comprises a free-running oscillator circuit having an oscillator transistor; a switching transistor operatively connected to said oscillator transistor; a time limiting circuit operatively connected to said switching transistor, said time limiting circuit having a timer transistor anda resistor and condenser providing a time constant, so that when said alarm switch is closed said acoustic generating means emits the acoustic alarm signal for a time period determined by said time constant, and the time period of the acoustic alarm signal is limited to a small fraction of the total closure period of the alarm switch.

2. The alarm timepiece of claim 1, wherein said freerunning oscillator circuit is connected directly to said battery, while said time-limiting circuit is connected through said alarm switch to said battery.

3. The alarm timepiece of claim 1, wherein said freerunning oscillator circuit is of the blocking type and connected between a capacitive element and a resistor element contained therein; the emitter electrode of said switching transistor, which is connected with said capacitative element, is connected through the primary the electronic alarm to a minimum.

4. The alarm timepiece of claim 1, wherein said freerunning oscillator circuit is an astable multivibrator and said acoustic generating means is adapted for being driven by coil means inserted in said oscillator circuit, the base electrode of the oscillator transistor being electrically connected with the collector electrode of the switching transistor, so as to reduce the power consumption of the electronic alarm to a minimum.

Claims

1. In an alarm timepiece comprising a timepiece movement; acoustic generating means mounted on said movement for generating an acoustic alarm signal; an electronic drive circuit mounted on said movement and having a detachable battery for providing current to said drive circuit; at least one alarm switch operatively connected with said movement and said drive circuit so that upon closure of same at a preset time said current flows through said drive circuit to initiate operation of same and cause said generating means to generate the acoustic alarm signal, the improvement wherein said generating means comprises a piezoelectric oscillator attached to a vibratable membrane mounted in said timepiece, said electronic drive circuit comprises a free-running oscillator circuit having an oscillator transistor; a switching transistor operatively connected to said oscillator transistor; a time limiting circuit operatively connected to said switching transistor, said time limiting circuit having a timer transistor and a resistor and condenser providing a time constant, so that when said alarm switch is closed said acoustic generating means emits the acoustic alarm signal for a time period determined by said time constant, and the time period of the acoustic alarm signal is limited to a small fraction of the total closure period of the alarm switch.

2. The alarm timepiece of claim 1, wherein said free-running oscillator circuit is connected directly to said battery, while said time-limiting circuit is connected through said alarm switch to said battery.

3. The alarm timepiece of claim 1, wherein said free-running oscillator circuit is of the Blocking type and connected between a capacitive element and a resistor element contained therein; the emitter electrode of said switching transistor, which is connected with said capacitative element, is connected through the primary winding of a transformer in said oscillator circuit, the secondary winding of which is at least partially connected operatively with said acoustic signal delivery means, with the base of the oscillator transistor, to thereby control said oscillator circuit with low current, and for interrupting the base current of said oscillator transistor substantially completely during the remaining closure period of the alarm switch which is devoid of the operational period of said acoustic signal delivery means so as to reduce the power consumption of the electronic alarm to a minimum.

4. The alarm timepiece of claim 1, wherein said free-running oscillator circuit is an astable multivibrator and said acoustic generating means is adapted for being driven by coil means inserted in said oscillator circuit, the base electrode of the oscillator transistor being electrically connected with the collector electrode of the switching transistor, so as to reduce the power consumption of the electronic alarm to a minimum.