US3744233A - Electric timepiece - Google Patents

Electric timepiece Download PDF

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Publication number
US3744233A
US3744233A US00168251A US3744233DA US3744233A US 3744233 A US3744233 A US 3744233A US 00168251 A US00168251 A US 00168251A US 3744233D A US3744233D A US 3744233DA US 3744233 A US3744233 A US 3744233A
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United States
Prior art keywords
base
collector
coil
circuit
transistor
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00168251A
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English (en)
Inventor
Y Tsuruishi
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Suwa Seikosha KK
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Suwa Seikosha KK
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Filing date
Publication date
Priority claimed from JP6651370A external-priority patent/JPS4943347B1/ja
Application filed by Suwa Seikosha KK filed Critical Suwa Seikosha KK
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    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C3/00—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means
    • G04C3/04—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a balance
    • G04C3/06—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a balance using electromagnetic coupling between electric power source and balance
    • G04C3/065—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a balance using electromagnetic coupling between electric power source and balance the balance controlling gear-train by means of static switches, e.g. transistor circuits
    • G04C3/069—Driving circuits using a single coil for detection and driving purposes
    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C3/00—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means
    • G04C3/08—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a mechanical oscillator other than a pendulum or balance, e.g. by a tuning fork, e.g. electrostatically
    • G04C3/10—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a mechanical oscillator other than a pendulum or balance, e.g. by a tuning fork, e.g. electrostatically driven by electromagnetic means
    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C3/00—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means
    • G04C3/08—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a mechanical oscillator other than a pendulum or balance, e.g. by a tuning fork, e.g. electrostatically
    • G04C3/10—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a mechanical oscillator other than a pendulum or balance, e.g. by a tuning fork, e.g. electrostatically driven by electromagnetic means
    • G04C3/108—Driving circuits

Definitions

  • ABSTRACT An electric timepiece having a driving circuit having a single coil inserted between the collector electrodes of two transistors, one being of the NPN type, the other being the PNP type.
  • a condenser is inserted between the collector electrode of one transistor and a base electrode of the other transistor, and a bias circuit for supplying self-bias is connected to the base electrode of the two transistors.
  • the driving circuit may be utilized with a time standard oscillator including a tuning fork oscillator.
  • Said tuning fork may be U-shaped, said single coil being mounted intermediate a U-shaped magnetic circuit mounted on a portion of said tuning fork.
  • One or more pairs of permanent magnets would be fixed to a balance wheel or tuning fork in order to close a magnetic path and the detecting and driving coils are inserted in this magnetic path.
  • the permanent magnets carried by the oscillating balance wheel or tuning fork are positioned so that the magnetic field thereof crosses the two fixed coils to induce a voltage therein responsive to the change of magnetic flux in said coil.
  • the driving transistor of the prior art arrangements is switched by the induced voltage in the detecting coil and electric current flows in the driving coil to maintain the oscillation of the balance wheel or tuning fork.
  • the energy supplied to the oscillator is a product of the induced voltage v in the driving coil and the current i flowing in said driving coil. If the direct current resistance of the driving coil is R, a Joule loss of Ri is caused by the current i. As this loss does not contribute to the oscillation of the time standard, it must be as small as possible, so that the current i must be as small as possible.
  • the induced voltage v in the driving coil must be increased.
  • the voltage v be large, and the current i and resistance R be small. Since the coil must be mounted in a limited space, the induced voltage v can only be increased by using a thin wired coil having a large number of turns. By having only a single coil, rather than both detecting and driving coils, the number of turns of the driving coil can be substantially increased for the same coil space. While driving circuits incorporating a single coil are known in the art, by improving such prior art circuits, substantial advantages are obtained.
  • a driving circuit for an electric timepiece including time standard oscillator means; and electric circuit means for maintaining the oscillation of said time standard oscillator means, said electric circuit means including a single coil positioned to cooperate with said time standard oscillator means for maintaining the oscillation thereof in response to driving current passed through said coil and a pair of transistors, one of said transistors being of the PNP type and other being of the NPN type.
  • the single coil is inserted between the collector electrodes of the two transistors, while a condenser is inserted between the collector electrode of one of said transistors and a base electrode of the other of said transistor.
  • Bias circuit means is provided for supplying self-bias to the base electrodes of the two transistors; a direct current voltage source is provided to supply energy to said electric circuit means.
  • the time standard oscillator means may be either a balance wheel or a tuning fork.
  • said tuning fork is preferably substantially U- shaped and provided with a U-shaped magnetic circuit mounted thereon and encompassing said coil.
  • the U- shaped magnetic circuit may consist of two pairs of spaced mounting plates secured to the ends of the tines of said tuning fork, the two pairs of plates being positioned in adjacent relation with said single coil fixedly mounted intermediate the plates defining each pair.
  • a pair of substantially semi-circular permanent magnets are mounted on the inner surfaces of each of said pairs of plates, to define a separate magnetic circuit passing through said coil, each consisting of one of said pairs of permanent magnets, the associated pairs of mounting plates, and the associated tine of said tuning fork.
  • Said coil is preferably substantially circular.
  • an object of this invention to provide an electric timepiece incorporating a driving circuit having a single coil for both detecting and driving.
  • Another object of the invention is to provide an electric timepiece having a driving circuit which may be utilized to maintain the oscillation of both balance wheel and tuning fork.
  • a further object of the invention is to provide an electric timepiece having a tuning fork particularly adapted for assembly in a compact case through the use of mass production.
  • FIG. 1 is a cross-sectional view of a balance wheel of one type of electric timepiece wherein permanent magnets are attached to said balance wheel;
  • FIG. 2 is a plan view of the balance wheel of FIG. 1;
  • FIG. 3 is a ciruit diagram of one conventional blocking type driving circuit for electric timepieces wherein one coil serves for detecting and driving;
  • FIGS. 40, b and'c are circuit diagrams of driving circuits for electric timepieces according to the invention.
  • FIGS. 5a, b and c are wave form diagrams showing output wave forms of the driving circuits of FIGS. 3 and FIG. 6 is a plan view of an electric wrist watch having a tuning fork according to the present invention
  • FIG. 7 is a plan view of an end portion of the tuning fork of FIG. 6;
  • FIG. 8 is a cross-sectional view taken along line A I A of FIG. 2;
  • FIG. 9 is an enlarged plan view. of the frame of the coil of the watch of FIG. 6;
  • FIG. 10 is a circuit diagram of another conventional driving circuit for electric timepieces having tuning forks.
  • FIG. 11 is a circuit diagram of another embodiment of the driving circuit according to the invention.
  • FIG. I wherein a conventional balance wheel is depicted, l is a balance wheel having upper and lower portions, 2 a balance staff, 3 and 4 are permanent magnets, 5 a single coil, 6 a supporting plate for the coil, and 7 are balancing weights.
  • Permanent magnets 30 and 3b are secured to the balance wheel of FIG. 2, two of them to the upper balance wheel and the other two to the lower balance wheel.
  • the coil 5 is disposed at the position where it is linked to said two magnetic fields as shown in FIG. 2.
  • FIG. 3 is a circuit diagram of a known blocking type of driving circuit wherein 8 is a battery, 9 a coil, I is a PNP type of transistor, 11 a NPN type of transistor, I2 a base resistor, 13 a base bias resistor for PNP type transistor l0, 14 a coupling condenser and 15 a variable resistor for selecting pulse width.
  • This circuit is a self-running blocking type, and the self-running period is determined by the time constant of the resistor 13 and the condenser 14.
  • the pulse width is determined by time constant of condenser 14, the resistor 13 and the internal resistance of the coil 9.
  • FIG. a shows the driving waveform taken at the collector of transistor II when the balance wheel of FIG. I is driven by the circuit of FIG. 3.
  • the width of a pulse 23 is always constant irrespective of the induced voltage in the coil.
  • the base electrode of PNP type transistor is biased sufficiently in the forward direction, so that a double driving pulse can not be produced. Therefore, when the balance wheel is driven in both directions during each reciprocation, an undersired pulse is produced as shown in FIG. 5a so that the isochronism of the balance wheel is disturbed.
  • the value of the circuit components of the circuit of FIG. 3 should be selected precisely, but the value of condenser 14 generally must be more than several thousand PF and it is worth the high initial cost to select the tolerance of the said condenser value within a short range.
  • the arrangement according to the invention provides a stabilized driving circuit wherein the defects of the conventional types of driving circuits are eliminated and a wide tolerance range of values of components is permitted. Further, the driving method is such that the balance wheel can self-start in both directions and can be driven alternately.
  • FIG. 41 shows three embodiments of the driving circuit according to the invention wherein I6 is an electric source of direct current, 17 a PNP type transistor, 18 a NPN type transistor, 19 a coil, 20 a base resistor for PNP type transistor 17, 21 a condenser, and 22 a base bias resistor for NPN type transistor 18.
  • This circuit is characterized by the fact that FNP type transistor 17 and NPN type of transistor I8 are generally maintained. in an operating region of linear characteristics, and that even a small quantity of detecting voltage induced in the coil can be directly amplified.
  • the self-starting characteristics of the balance wheel in the embodiments of FIGS. 3a and b are higher and more stabilized than in the embodiment of FIG. 3c.
  • the two driving transistors incorporate self-biasing means wherein the base and the collector electrodes of the transistors are coupled by resistors. Therefore, the driving circuit according to the invention produces highly reliable selfstarting, and as the base potential of the transistors are not fully biased by a small charge in the condenser, double pulses are symmetrically produced, so that the balance wheel is driven alternately without disturbing the isochronism, as shown'in FIG. 5b.
  • FIG. 5b and FIG. 50 show the wave forms when the balance wheel of FIG. I is driven by using a circuit of FIG. 4 according to the invention.
  • FIG. 5b shows the voltage wave form at the collector electrode of transistor I8, and
  • FIG. 50 shows a voltage wave form at the collector electrode of the transistor 17.
  • the pulse width is not determined only by the circuit constants, so a wide tolerance in the range of values of components can be permitted.
  • 31 is a voltage source of direct current, 32 a tuning fork, 33 a coil, 34 a magnet plate, 35 a frame for supporting coil 33, 36 a ratchet wheel, 37 a block containing the driving circuit, 38 a connecting terminal connecting a negative pole of the battery 31 to circuit block 32, and 39 a connecting terminal connecting the coil 33 to the circuit block 37.
  • the diameter of battery 31 is generally somewhat smaller than a radius of a movement of the wrist watch, and the tuning fork 32 is provided with curved tines in order to incorporate the battery 31.
  • the end portion of the tuning fork 32 is connected to mounting plates 34 of magnetic material by pins 40 as shown in FIG. 7. An upper plate.
  • the coil 33 is fixed to the frame 35 as shown in FIG. 9, and inserted in the space between the permanent magnets at the end portion of the tuning fork leaving a proper space in order that said coil does not contact tuning fork 32.
  • Frame 35 is fixed to the plate of the watch. Electrically conductive portions 42 and 43 are formed on frame 35 in order to receive a lead wire of the coil 33.
  • Frame 5 includes a printed board having a thin copper plate disposed therein, a pattern defining conductors 42 and 43 being etched in said plate by an etching reagent.
  • the conductive portion 42 of coil frame 45 serves to receive one end of the lead wire of coil 33 and to connect circuit block 37 with the negative pole of the battery.
  • the conductive portion 43 serves to receive the other end of the lead wire of the coil 33.
  • the tuning fork according to this invention may be energized by a coil 3 having its two terminals connected to the driving circuit shown in FIG. 10, wherein 44 is a battery, 45 a coil, 46 a NPN type transistor, 47 a PNP type transistor, 48 a base resistor of said NPN type transistor 46, 49 a trigger condenser, 50 a variable resistor for regulating the amplitude of the tuning fork, and 51 a base resistor for the PNP type transistor 17.
  • This circuit is known as an astable blocking oscillator.
  • the magnetic field produced by the magnets covers almost the whole coil, the strength of the magnetic field on a surface of the coil is almost uniform, and its strength can be increased. For this reason, sufficient flux density can be obtained from a relatively thin magnet, the turns of the coil can be reduced to about A: of the number of the conventional coil, and a thin wrist watch having a tuning fork can be obtained.
  • one portion of the tuning fork according to the invention is used as part of the magnetic path, so that it is not necessary to weld the tuning fork and the end portion by a silver solder. Rather, the end portion can be easily secured by a pin or a screw.
  • the tuning fork is formed of a material with constant elasticity in response to the temperature changes in order to constantly maintain the frequency of the tuning fork. It is not desirable to heat-treat such material at high temperature, as by silver soldering. Accordingly, the construction of the invention is advantageous for maintaining the characteristics of the tuning fork.
  • said driving circuit means includes a condenser inserted between the collector electrode of one of said transistors and a base electrode of the other of said transistors, and
  • bias circuit means for supplying self-bias to the base electrodes of said two transistors.
  • said bias means includes a first resistor connected between the base of said PNP transistor and the collector of said NPN transistor, a second resistor connected between the base of said'NPN transistor and the emitter of said PNP transistor.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electric Clocks (AREA)
  • Electromechanical Clocks (AREA)
US00168251A 1970-07-31 1971-08-02 Electric timepiece Expired - Lifetime US3744233A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP6651370A JPS4943347B1 (enrdf_load_stackoverflow) 1970-07-31 1970-07-31
JP7773270 1970-09-07
JP8497470 1970-09-30

Publications (1)

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US3744233A true US3744233A (en) 1973-07-10

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US00168251A Expired - Lifetime US3744233A (en) 1970-07-31 1971-08-02 Electric timepiece

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US (1) US3744233A (enrdf_load_stackoverflow)
FR (1) FR2099714B1 (enrdf_load_stackoverflow)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3456137A (en) * 1965-06-08 1969-07-15 Messrs Gebruder Junghans Gmbh Tuning fork devices
US3596461A (en) * 1968-02-06 1971-08-03 Robert W Reich Electromagnetic driving system for timepieces

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3456137A (en) * 1965-06-08 1969-07-15 Messrs Gebruder Junghans Gmbh Tuning fork devices
US3596461A (en) * 1968-02-06 1971-08-03 Robert W Reich Electromagnetic driving system for timepieces

Also Published As

Publication number Publication date
DE2138568B2 (de) 1976-04-29
DE2138568A1 (de) 1972-02-03
FR2099714B1 (enrdf_load_stackoverflow) 1975-02-07
FR2099714A1 (enrdf_load_stackoverflow) 1972-03-17

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