Electronic alarm wristwatch

Abstract

This invention relates to an electronic alarm wristwatch wherein apertures are provided on the back cover to release alarm sound generating upon the coincidence of the time preset by an alarm-presetting device and that designated by a time display or time keeping means. A sound-emitting piezo-electric or electro-strictive element is fixed to the membrane which is dish-shaped and has a plurality of concentric wrinkles, said membrane is so placed in the watch case as not to waste any space and insures water- and dust-proofing. A distribution board is fixed to the wrinkled portion of said membrane to provide the required electric current, thereby providing an electric alarm watch which sounds freely and is not disturbed by oscillation of the wrist.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an electronic alarm wristwatch.

2. Prior Art

Prior art devices disclose an electronic alarm wristwatch in which a form of electro-magnetic buzzer is employed to beat the glass or metal back cover by means of an electro-magnetically driven hammer or other oscillating means. However, this type of alarm device requires considerable space to allow the oscillating means to work and additional space to house electro-magnets, making it necessary to enlarge the size of the watch.

In an attempt to overcome these drawbacks, an electronic buzzer in which a piezo-electric or electro-strictive element has been fixed to the membrane has been used instead of the aforementioned electro-magnetic buzzer. The alarm wristwatch of the electronic buzzer type has on its back cover an aperture to release the sound emanating from the membrane out of the watch case; therefore, the watch is neither waterproof nor dustproof. In order to improve this shortcoming, the case band has been compressed with a composite back cover comprising a flat membrane and the back cover fastened together as a single entity. However, the composite back cover also has a drawback in that there exists a large and unnecessary space surrounded by the membrane and the inside wall of the back cover. By compressing the case band and the composite back cover together the size of the watch must necessarily be large. In addition, the watch of this type employs a driving means utilizing a piezo-electric or electro-strictive element, whereby electric connection between alarm circuit provided on the watch movement and the piezo-electric or electro-strictive element fixed to the membrane is accomplished by a terminal pin provided on the membrane and a terminal spring provided on the movement which resiliently contacts said terminal pin. This necessitates the device have an area in which the terminal pin and terminal spring are arranged between the movement and the membrane. Therefore, in conventional devices using a flat membrane, the size of the watch must be large enough to provide said space.

A further drawback in above arrangement exists in that the membrane does not oscillate properly since the terminal pin provided on said membrane is elastically attached to the terminal spring in the watch movement. It is also difficult and impractical, for example, to arrange and place parts such as an alarm circuit, in addition to the piezo-electric or electro-strictive element, on the membrane for the following reasons: (1) such elements tend to interfer with the oscillation of the membrane, (2) such elements require area which is limited, and (3) there is a possibility of electrical disconnection.

Resilient contact between the terminal pin and terminal spring also presents a problem in that electric connection may not always be effected due to the nature of the placement of the membrane and the watch movement upon which the terminal pin and terminal spring are respectively fixed.

BRIEF SUMMARY OF THE INVENTION

The primary object of this invention is to provide an electronic alarm wristwatch comprising a time display means, an alarm presetting device, an alarm presetting circuit operating upon the coincidence of the time preset by the alarm presetting device and that designated by the time display means, a piezo-electric or electro-strictive element driven by said circuit, a membrane on which said element is fixed, a back cover having apertures to release sound emanating from said membrane out of the watch case, and a case band supporting said back cover, wherein said membrane is dish-shaped with a plurality of wrinkles formed by a metal forming process, and having a central portion and brim thereon that are flat. The piezo-electric or electro-strictive element is fixed on said central portion, and said brim is held between said back cover and said case band.

Another object of this invention is to provide an electronic alarm wristwatch having a dish-shaped membrane with a wrinkled portion. On the wrinkled portion is installed a distribution plate, said plate having a ring-like conductive portion thereon which connects to a touch spring thereby providing electric connection.

Still another object of this invention is to provide an electronic alarm wristwatch having an alarm circuit fixed on the distribution plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the back cover of a known alarm wristwatch.

FIG. 2 is a sectional view along Line II--II' of FIG. 1.

FIG. 3 is a plan view of the buzzer unit of an embodiment of this invention.

FIG. 4 is a sectional view along Line IV--IV' of FIG. 3.

FIG. 5 is a sectional view of the overall structure of the watch described in the same embodiment, with a schematic electric circuit coupled to the watch.

FIG. 6 is a sectional view of a variation of the embodiment shown in FIG. 5 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 in which a plan view of the back cover of a known electric alarm wristwatch is shown for comparison, back cover 10 has plural apertures 20, 22, 24, 26, 28, 30, 32 and 34 provided in slope 12 of said back cover 10 so that the sound being generated within the case can efficiently be heard through the apertures without being blocked by the wrist. Referring to FIG. 2 which shows a sectional view along Line II-II' of FIG. 1, back cover 10 is dish shaped having a slope 12, brim 14, and recessed room 18 surrounded by the inner wall of back cover 10. A plan view of the buzzer unit of an embodiment of this invention is shown in FIG. 3 where buzzer unit 36 has a covering case consisting of membrane 38 made of titanium material which has little material loss of oscillations and prevents erosion from sea water.

The construction of buzzer unit 36 is better shown in FIG. 4, where membrane 38 has a dish shape provided with plural concentric wrinkles 40, 42, 44 and 46 including brim 40 and central flat portion 46. The term "wrinkles" as employed herein may include the bent portion and a flat portion or only a bent portion or only a flat portion. The membrane 38 can be easily processed in any manner suited for mass production, such as by a metal forming process, to form wrinkles. Membrane 38 has a recessed space 50 surrounded by flat brim 40 and inside wall 48. Piezo-electric or electro-strictive element 54, made of BaTiO.sub.3 or Pb(TiZr)O.sub.3, and distribution plate 62 are arranged in recessed space 50 with piezo-electric or electro-strictive element 54 adhered to central flat portion or wrinkle 46 of inside wall 48 with a conductive adhesive agent of epoxy resin. Preformed on each side of element 54 is a silver electrode and after being fixed to membrane 38 it is treated for polarization with a DC electric field from the outside. Distribution plate 62 is fixed concentrically along wrinkle 44 of membrane 38 with an insulative adhesive agent of epoxy resin. This plate 62 includes conductive portions 66 thereupon. In this embodiment, distribution plate 62 is made of a glass-containing epoxy plate, and gold-plated, ring-shaped conductive portion 66 is provided thereupon. Said plate 62 has a hole 68 at the center for soldering operation, through which soldering of lead line 70 to the electrode of piezo-electric or electro-strictive element at soldering portion 56 is possible even after distribution plate 62 has been fixed onto membrane 38. In addition, conductive portion 66 has a perforation 58 through which lead line 70 is passed, one end thereof reaching soldering portion 56 to be soldered and the other end reaching soldering portion 60 of conductive portion 66 to be soldered, thus enabling electrical connection to the system. Upon completion of the soldering operation, sheet 72 made of any soft material is coated or secured over hole 68, the purpose of which is to prevent extraneous substances from falling onto membrane 38 which would impede proper oscillation of said membrane 38. The soft material used for sheet 72 is preferably made of air circulating fiber so as to lessen the possibility of impedance caused by sound pressure accompanying oscillation of said membrane. Since the sound originates at the central portion 46, rim 40 and wrinkles 42 and 44 of membrane 38 have little or no effects upon the sound.

Buzzer unit 36 thus constructed has less chance of damage with respect to the piezo-electric or electro-strictive element 54 and of disconnection of lead line 70, since lead line 70 is distributed within space 52 surrounded by distribution plate 62 and central portion 46 of membrane 38 and since the distribution plate 62 act as a mechanical shield for piezo-electric or electro-strictive element 54 and lead line 70.

The overall structure of the watch of this invention is shown in FIG. 5. Watch 74 of this embodiment comprises the buzzer unit 36 which is installed in recessed space 18 formed by back cover 10. The circular rim of the buzzer unit is removably fixed to the room between flat rim 40 of membrane 38 and rim 14 of back cover 10 and the inner bottom surface of band 78 having rubber packing 79 positioned adjacent thereto. This arrangement makes it possible that when any extraneous substances enter between the outside wall of membrane 38 and inside wall 16 of back cover 10 through apertures 20, 22, 24, 26, 28, 30, 32 and 34 and impede oscillation of the membrane 38, the removability of back cover 10 and membrane 38 makes it easy to eliminate such substances. The central portion or wrinkle 46 of membrane 38, is spaced an appropriate distance from inside wall 16 of back cover 10, so that it is free to move. Further, an intermediate rubber packing 79 is arranged between case band 76 and rim (or wrinkle) 40 of membrane 38, all of which are firmly fixed to back cover 10 by ring screw 80 which treadingly engages case band 76. Instead of using ring screw 80 as in the present embodiment, back cover 10 may be directly fixed to case band 76. The use of the rubber packing between case band 76 and rim (or wrinkle) 40, either with or without screws, results in waterproofing and dustproofing the watch.

The embodiment as shown in FIG. 5 has watch movement 82 provided with alarm circuit 84, both of which are completely sealed within the space formed by membrane 38, case band 76 and glass 86. A portion of watch movement 82 which is situated below the level of rim 40 of membrane 38, is placed in recessed space 50 enclosed by membrane 38. This is because of the dish shape of the membrane which enables said membrane to be placed along the inside wall 16 of back cover 10 within recessed space 18 of back cover 10 so as to eliminate wasteful space. Accordingly, the thickness and size of the watch is reduced by that much of the portion of movement 82 which is contained in recessed space 50. In this embodiment, the measurements of respective parts are as follows: from the base of inside wall 16 of back cover 10 to rim 14: 2.9 mm; from rim 40 of membrane 38 to the base of the outside wall of central portion 46: 2.8 mm; from wrinkle 44 of membrane 38 to base of the inside wall of central portion 46: 0.5 mm; the thickness of the membrane: 0.1 mm; and the thickness of distribution plate: 0.2 mm. In this connection a maximum 2.1 mm of watch movement 82 can be contained within recessed space 50 of said membrane 38.

Thin insulating board 98 and metallic terminal spring 102 are fixed together by plastic pins 90 and 94 provided on movement 82 by means of heat press at the tips of pins 90 and 94. Electrical connection is effected by means of terminal spring 102 resiliently contacting conductive portion 66 on distribution plate 62 when back cover 10 and buzzer unit 36 are clamped by case band 76. Separation of watch movement 82 from buzzer unit 36 is facilitated since no lead line is used for electrical connection between conductive portion 66 and terminal spring 102. To cope with the possible shifting of the point of contact on conductive portion 66 by terminal spring 102 resulting from clamping of back cover 10 and buzzer unit 36 to case band 76, a ring-like conductive portion 66 surrounds circular track 64 (shown by broken line in FIG. 3) with which electrical connection is effected at any random point as buzzer unit 36 rotates at the time of clamping. Thus it is not necessary to establish a specific point of contact.

The electrode of piezo-electric or electro-strictive element 54, which is fixed to membrane 38 with a conductive adhesive agent, is grounded to a plate on watch movement 82 via membrane 38, back cover 10, ring screw 80 and case band 76. Terminal spring 102 is electrically connected by lead line 106 from soldering portion 104 to output terminal 108 of alarm circuit 84. Battery 110 is electrically connected on the positive side to the plate (not shown) on watch movement 82 via lead line 112.

A conventional time display means is provided in watch movement 82, said time indicator comprising any of the following: (1) a device using a vibrator such as a balance wheel or a tuning fork as a time standard, a series of reduction wheels, time indicating hands axially supported by said wheels, and a dial; (2) a device comprising an oscillator with crystal vibrator serving as a time standard, a series of frequency dividers, stepping motor driven by an output from said frequency dividers to move time indicating hands and a dial, or (3) an electro-optic display such as a liquid crystal display device, or a light emitting diode device in which the output from the frequency divider is counted by a calculator or counters and converted by a decoder.

Also installed in this electronic alarm wristwatch are a conventional alarm presetting device which is externally operative, and a conventional alarm circuit which is controlled by the coincidence of the time preset by said alarm presetting device and the arrival of said time indicated by the time display means. Said alarm circuit may be so constructed that piezo-electric or electro-strictive element is driven by frequency signals from a crystal oscillator, or it may be constructed according to the embodiment as described below.

A conventional unlocking switch 114, controlled by the aforementioned coincidence of time, is directly connected to battery 110 so as to open or shut off the current route from battery 110 which connects to alarm circuit 84. Alarm circuit 84 comprises alarm oscillator circuit 116 and alarm presetting circuit 118. Said alarm oscillator circuit 116 basically employs known unstable or free-running multivibrator; in the present embodiment said circuit 116 comprises NPN-type transistors 120 and 122, resistors 124, 126 and 128, booster coil 130 which is connected in parallel with piezo-electric element 54, and condensers 132 and 134.

Employing a known CR-type timer circuit as a basis, alarm presetting circuit 118 comprises resistors 136, 138 and 140, condenser 142 and NPN-type transistors 144 and 146, and operates upon the constant time designated by resistor 136 and condenser 142. Output port 148 for transistor 144 is connected to the base of transistor 146. Further, the collector of transistor 146 is connected to the base of transistor 122 in alarm oscillator circuit 116 thereby controlling alarm sounding time.

In this embodiment the capacity of each part may be specified as follows: battery: a mercury type 1.3v; resistor 136: 1M.OMEGA.; condenser 142: 1.mu.F; alarm sounding time within alarm presetting circuit: about 1-2 seconds; in alarm oscillator circuit 116: condenser 132: 3300 pF; condenser 134: 330 pF; resistor 126: 33 K.OMEGA.; resistor 128: 33 K.OMEGA.; and oscillating frequency: about 4K Hz. A maximum sound effect is obtained when the resonance frequency of wrinkle 46 on membrane 38 of buzzer unit 36 is about equivalent to the oscillating frequency. The titanium membrane 38 shaped and supported as indicated is particularly compatible with said oscillating circuit.

The operation of alarm circuit 84 is as follows: U on the arrival of a preset time, unlocking switch 114 closes, charging the positive booster coil 130 side of condenser 134, and, since resistor 126 has a lower resistance than resistor 128, transistor 122 is activated (ON). Thus electrical current flows in booster coil 130, accummulating magnetic energy therein. Voltage between base emitters in transistor 120 increases according to the constant time determined by resistor 128 and condenser 134, and at the same time condenser 132 is charged on the positive resistor 124 side. Having thus activated (ON) transistor 120, the voltage between transistor 122 base emitters decreases rapidly, deactivating (OFF) transistor 122. Thereupon the aforementioned magnetic energy stored in booster coil 130 is discharged at once, generating high voltage in each end of booster coil 130, and drives piezo-electric element 54 which is connected parallel to booster coil 130. When transistor 120 is deactivated (OFF), the voltage between transistor 122 base emitters begins to increase according to the time constant determined by resistor 126 and condenser 132. Thereupon condenser 134 is again charged on the positive booster coil 130 side. When transistor 122 is activated (ON), the voltage in the base emitters of transistor 120 decreases rapidly, deactivating (OFF) transistor 120. Repeating the above operation, each time transistor 122 is activated (ON), the electricity flows to booster coil 130. Oscillation at the rate of approximately 4K Hz causes piezo-electric element 54 to keep sounding.

Meanwhile, in alarm presetting circuit 118, transistors 144 and 146 are initially deactivated (OFF) when unlocking switch 114 is shut, but as condenser 142 is gradually charged via resistor 136, the base voltage in transistor 144 increases accordingly and activates (ON) said transistor 144. The time required for unlocking switch 114 to close and transistor 144 to activate is 1-2 seconds as mentioned previously. Transistor 146 is activated (ON) as the voltage across resistor 140 connecting to transistor 144 emitter increases. Thereupon the voltage in transistor 122 base emitters is forcibly decreased, deactivating transistor 122 and thereby stopping the drive of piezo-electric element 54. This condition remains until unlocking switch 114 opens once again.

Now referring to FIG. 6 showing a sectional view of a variation of the embodiment shown in FIG. 5, the membrane 150 is dish-shaped having a plurality of wrinkles 152, 154, 156 and 158 formed by a stamping, or progressive drawing process. Membrane 150 is arranged along inside wall 16 of back cover 10 so that appropriate space is maintained for wrinkle 158 to oscillate properly. Piezo-electric element 54 is fixed to wrinkle 158 on membrane 150 by a conductive adhesive agent. The soldering portion 56 at one end of said element 54 is soldered to lead line 118 which connects to output port 108 of alarm circuit 84. Alarm circuit 84 is installed on the underside of distribution plate 160 which is fixed to wrinkle 154 of membrane 150.

Terminal 164 in alarm circuit 84 is soldered via lead line 166 to ring-shaped conductive portion 170 which is inside of concentric conductive portion 66 on the upper side of distribution plate 160 through hole 172 provided in said distribution plate 160. The other terminal 162 in alarm circuit 84 is electrically connected to conductive portion 66 on the upper surface of distribution plate 160.

Buzzer unit 174 comprises membrane 150, piezo-electric or electro-strictive element 54, distribution plate 160, and alarm circuit 84. The watch movement comprises a time display means, an alarm presetting device, unlocking switch 114 linked to said alarm presetting device, and battery 110. In addition, terminal springs 102 and 178 are insulated from each other so that each independently and resiliently contact respective conductive portions 170 and 66 of buzzer unit 174. Terminal spring 178 is fixed onto thin insulating board 100, both of which are in turn firmly held by means of heat press to the tips of plastic pins 92 and 96 fixed to watch movement 176. Terminal spring 102 is connected to the negative side of battery 110, terminal spring 178 connects to the positive side via unlocking switch 114. The positive side of battery 110 is grounded to the base plate (not specifically shown) of watch movement 176, and membrane 150, having piezo-electric or electro-strictive element 54 thereon, is likewise electrically connected to the base plate of watch movement 176 via back cover 10, ring screw 80 and case band 76. Accordingly, upon the arrival of a preset time unlocking switch 114 closes and activates alarm circuit 84 in buzzer unit 174. Thereupon sound waves emanate from central portion 158 of membrane 150 on which piezo-electric or electro-strictive element 54 is fixed.

According to the embodiments described above, the use of the dish-shaped membrane with its plural wrinkles enables simple installation of the piezo-electric element, distribution plate, alarm circuit, etc. on the appropriate wrinkles without hindrance to the waterproofing and dustproofing functions. Additionally, the limited space within the watch case is most effectively utilized by the containment of a portion of the watch movement within the recessed space on the membrane, thus realizing the manufacture of a thinner, smaller electric alarm wristwatch.

Further, the buzzer unit assembly is simplified by the fact that electrical connection can be effected at random since it is not necessary to choose a specific point of contact with regard to the rotation of the buzzer unit. In the event of a failure, or of an inspection of the buzzer unit, repair or inspection is facilitated since, as an independent entity, the unit can be easily removed from the watch case and reinstalled equally easily.

As seen above, the electronic alarm wristwatch of this invention excels in serviceability which adds to its commercial value.

Claims

We claim:

1. An electronic alarm wristwatch comprising a time display means, an alarm presetting device, an alarm circuit means for operating upon the coincidence of the time preset by said alarm presetting device and that designated by said time display means and for providing an electrically varying signal upon said coincidence, an electro-means for vibrating when energized by said alarm circuit with said varying signal, a membrane on which said electro-means is fixed to be thereby vibrated, a back cover having apertures to release sound waves emanating from the membrane out of the watch case, and a case band holding said back cover, wherein said membrane is dish shaped with a plurality of concentric wrinkles, the central portion and rim thereof are flat, said electro-means is fixed on said central portion, and said rim is placed between said back cover and case band.

2. An electronic wristwatch according to claim 1, wherein said electro means is selected from the group consisting of a piezo-electric element and an electro-strictive element.

3. An electronic alarm wristwatch according to claim 1, wherein said back cover can be separated from said membrane.

4. An electronic alarm wristwatch according to claim 2, wherein a distribution plate is provided for connecting electric current necessary to drive said electro means, said distribution plate being fixed onto a wrinkle of said membrane.

5. An electronic alarm wristwatch according to claim 4, wherein a watch movement is encased within the watch case, said watch movement having a terminal spring therein, and at least one ring-shaped electric conductor arranged on the distribution plate to provide electrical connection to said terminal spring.

6. An electronic alarm wristwatch according to claim 4, wherein an opening is provided in the central portion of the distribution plate for access thereto.

7. An electronic alarm wristwatch according to claim 6, wherein said opening is closed with a soft material.

8. An electronic alarm wristwatch according to claim 5, wherein a perforation is arranged in the conductive portion of the distribution plate through which electric connection is effected between the electro-means and the conductor.

9. An electronic alarm wristwatch according to claim 4, wherein an alarm circuit is fixed onto the distribution plate.

10. An electronic alarm wristwatch according to claim 4, wherein said alarm circuit is placed between the distribution plate and the membrane.

11. An electronic alarm wristwatch according to claim 1, wherein a rubber packing is placed between the case band and the membrane.