CA2048826A1 - Two hand movement for timepiece with stepping motor - Google Patents
Two hand movement for timepiece with stepping motorInfo
- Publication number
- CA2048826A1 CA2048826A1 CA 2048826 CA2048826A CA2048826A1 CA 2048826 A1 CA2048826 A1 CA 2048826A1 CA 2048826 CA2048826 CA 2048826 CA 2048826 A CA2048826 A CA 2048826A CA 2048826 A1 CA2048826 A1 CA 2048826A1
- Authority
- CA
- Canada
- Prior art keywords
- center
- wheel
- frame
- stub
- minute
- Prior art date
- 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.)
- Abandoned
Links
Classifications
-
- 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
- G04C3/008—Mounting, assembling of components
-
- 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
- G04C3/14—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means incorporating a stepping motor
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electromechanical Clocks (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved movement for a timepiece of the type having an hour hand, a minute hand, driving circuit adapted for connecting to an energy cell, a stepping motor, a plastic frame member having a dial side and a back side, and adapted to hold the stepping motor, and a gear train supported by said frame member and arranged to drive the hour hand and minute hand the said stepping motor. The gear train comprises a first assembly of a center wheel and center pinion with center wheel driven directly by the stepping motor, a second assembly of a minute wheel and minute pinion with minute wheel driven directly by the center pinion, and an hour wheel driven directly by the minute pinion. The improvement comprises a stub extending from the front side of said frame, defining a center bore extending through the frame and stub, a spindle extending through the center bore and rotatably supporting the first assembly in the frame. The spindle includes a bushing on the front side of said frame adapted to hold the minute hand and to control axial clearances of the first assembly. The bushing may be separate from the spindle, but preferably is integral therewith. The center wheel is frictionally engaged with the spindle on the back side of said frame. A collar fixed to said hour wheel rotatably supports the hour wheel on the stub and also holds the hour hand.
An improved movement for a timepiece of the type having an hour hand, a minute hand, driving circuit adapted for connecting to an energy cell, a stepping motor, a plastic frame member having a dial side and a back side, and adapted to hold the stepping motor, and a gear train supported by said frame member and arranged to drive the hour hand and minute hand the said stepping motor. The gear train comprises a first assembly of a center wheel and center pinion with center wheel driven directly by the stepping motor, a second assembly of a minute wheel and minute pinion with minute wheel driven directly by the center pinion, and an hour wheel driven directly by the minute pinion. The improvement comprises a stub extending from the front side of said frame, defining a center bore extending through the frame and stub, a spindle extending through the center bore and rotatably supporting the first assembly in the frame. The spindle includes a bushing on the front side of said frame adapted to hold the minute hand and to control axial clearances of the first assembly. The bushing may be separate from the spindle, but preferably is integral therewith. The center wheel is frictionally engaged with the spindle on the back side of said frame. A collar fixed to said hour wheel rotatably supports the hour wheel on the stub and also holds the hour hand.
Description
~ PI-1285 TWO HAND MOVEMENT FOR TIMEPIE OE
WITH A STEPPING MOTOR
This invention relates generally to two hand quartz analog timepieces driven by a stepping motor. More particularly, the invention relates to an improved arrangement for the gear train in a timepiece having a plastic frame, and wherein a center wheel is driven directly by a stepping motor, which is powered by a thin large diameter energy cell.
BACKGROUND OF THE INVENTION
Electronic timepieces of the "analog" type, i.e., having conventional rotating hands, have been developed wherein a stepping motor is accurately driven from a time based electrical driving signal. The driving signal may come from a transistor pulse-producing circuit or from an integrated circuit having a quartz oscillator time base.
Improved movements for two hand timepieces with plastic frames have been developed using a center wheel having teeth of ogival shape at the periphery which are driven directly by a stepping motor pinion. The pinion comprises two pins which rotate 180 when the stepping motor is energized to d~82~
advance the center wheel. Such a movement is disclosed in U.S.
Patent 4,647,218, issued March 3, 1987, to Paul Wuthrich and assigned to the present assignee. In that patent, the center wheel and drive pinion were located just beneath the dial of the watch in order to allow the center wheel to overlap the relatively thick energy cell. This arrangement reversed the conventional positions of the hour hand and minute hand and required a special bridge bearing to support the center spindle. Further improvements in this movement were made in U.S. Patent 4,725,749, issued February 16, 1988, to Paul Wuthrich and assigned to the present assignee, wherein the bridge bearing was eliminated and a fi~ed separate center post, which was inserted into the plastic frame, rotatably supported the center spindle. Axial clearance (end-shake) of the center spindle was controlled between a bushing on the spindle and a the center post.
The recent commercial availability of long life 3 v.
lithium energy cells, rather than the 1.5 v. silver or mercury cells fo~ which the above movements were designed, has led to desirability to reconfigure and rearrange of the physical components in the available space inside a watch movement.
Specifically, lithium cells of long life are available which are relatively thin, but of large diameter. Therefore, the gear train, stepping motor and other components must be 53 2 J~
arranged in an optimum way so that the overall thickness of the movement, including that of the energy cell, will not be too great.
Constructions are known for two hand movements in which a large center wheel at the back of the movement is driven directly by teeth of the stepping motor pinion to rotate the minute hand, with other gear reduction members arranged to drive the hour hand. See Japanese Utility Model 55-52395 which requires front and back frame plate members. However, such constructions are not suitable for single piece plastic frame construction.
Accordingly, one object of the present invention is to provide an improved two hand movement for a quartz analog timepiece suitable for a plastic frame incorporating a large diameter, relatively thin, energy cell.
Another object of the invention is to provide an improved movement for a two hand quartz analog timepiece wherein a center wheel at the back of the movement is directly driven by a stepping motor.
&
PI-12~5 Still another object of the invention is to provide an improved central bearing structure for the gear train in a two hand quartz analog timepiece.
DRAWINGS
The invention, both as to organization and method of practice, together with further objects and advantages thereof, will best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:
Fig. 1 is a top plan view of the improved movement, looking from the dial side with dial and other portions omitted for clarity, Fig. 2 is a bottom plan view of the improved movement, locking from the back side opposite the dial, Fig. 3 is a developed, cross-sectional side elevational view, taken along lines III-III of Fig. 1, Fig. 4 is a partial side elevational view, showing an alternate preferred embodiment of the invention.
WITH A STEPPING MOTOR
This invention relates generally to two hand quartz analog timepieces driven by a stepping motor. More particularly, the invention relates to an improved arrangement for the gear train in a timepiece having a plastic frame, and wherein a center wheel is driven directly by a stepping motor, which is powered by a thin large diameter energy cell.
BACKGROUND OF THE INVENTION
Electronic timepieces of the "analog" type, i.e., having conventional rotating hands, have been developed wherein a stepping motor is accurately driven from a time based electrical driving signal. The driving signal may come from a transistor pulse-producing circuit or from an integrated circuit having a quartz oscillator time base.
Improved movements for two hand timepieces with plastic frames have been developed using a center wheel having teeth of ogival shape at the periphery which are driven directly by a stepping motor pinion. The pinion comprises two pins which rotate 180 when the stepping motor is energized to d~82~
advance the center wheel. Such a movement is disclosed in U.S.
Patent 4,647,218, issued March 3, 1987, to Paul Wuthrich and assigned to the present assignee. In that patent, the center wheel and drive pinion were located just beneath the dial of the watch in order to allow the center wheel to overlap the relatively thick energy cell. This arrangement reversed the conventional positions of the hour hand and minute hand and required a special bridge bearing to support the center spindle. Further improvements in this movement were made in U.S. Patent 4,725,749, issued February 16, 1988, to Paul Wuthrich and assigned to the present assignee, wherein the bridge bearing was eliminated and a fi~ed separate center post, which was inserted into the plastic frame, rotatably supported the center spindle. Axial clearance (end-shake) of the center spindle was controlled between a bushing on the spindle and a the center post.
The recent commercial availability of long life 3 v.
lithium energy cells, rather than the 1.5 v. silver or mercury cells fo~ which the above movements were designed, has led to desirability to reconfigure and rearrange of the physical components in the available space inside a watch movement.
Specifically, lithium cells of long life are available which are relatively thin, but of large diameter. Therefore, the gear train, stepping motor and other components must be 53 2 J~
arranged in an optimum way so that the overall thickness of the movement, including that of the energy cell, will not be too great.
Constructions are known for two hand movements in which a large center wheel at the back of the movement is driven directly by teeth of the stepping motor pinion to rotate the minute hand, with other gear reduction members arranged to drive the hour hand. See Japanese Utility Model 55-52395 which requires front and back frame plate members. However, such constructions are not suitable for single piece plastic frame construction.
Accordingly, one object of the present invention is to provide an improved two hand movement for a quartz analog timepiece suitable for a plastic frame incorporating a large diameter, relatively thin, energy cell.
Another object of the invention is to provide an improved movement for a two hand quartz analog timepiece wherein a center wheel at the back of the movement is directly driven by a stepping motor.
&
PI-12~5 Still another object of the invention is to provide an improved central bearing structure for the gear train in a two hand quartz analog timepiece.
DRAWINGS
The invention, both as to organization and method of practice, together with further objects and advantages thereof, will best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:
Fig. 1 is a top plan view of the improved movement, looking from the dial side with dial and other portions omitted for clarity, Fig. 2 is a bottom plan view of the improved movement, locking from the back side opposite the dial, Fig. 3 is a developed, cross-sectional side elevational view, taken along lines III-III of Fig. 1, Fig. 4 is a partial side elevational view, showing an alternate preferred embodiment of the invention.
2 ~
SUMMARY OF THE INVENTION
Briefly stated, the invention comprises an improved movement for a timepiece of the type having an hour hand, a minute hand, driving circuit adapted for connecting to an energy cell, a stepping motor,- a plastic frame member having a dial side and a back side, and adapted to hold said stepping motor, and a gear train supported by said frame member and arranged to drive the hour hand and minute hand from said stepping motor, said gear train comprising a first assembly of a center wheel and center pinion with said center wheel driven directly by the stepping motor, a second assembly of a minute wheel and minute pinion with said minute wheel driven directly by said center pinion, and an hour wheel driven directly by said minute pinion, wherein the improvement comprises a stub extending from the front side of said frame, said stub defining a center bore extending through the frame and stub, a spindle extending through said center bore and rotatably supporting said first assembly in the frame, said spindle including a bushing on the f ront side of said frame adapted to hold the minute hand and to control axial clearance for the first assembly, said center wheel frictionally engaged with said spindle on the back side of said frame, and a collar fixed to said hour wheel and adapted to rotatably support said hour wheel on the stub, said collar further adapted to hold the hour 2 i~
hand. The bushing may be separate from the spindle, but preferably is integral therewith.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figs. 1 and 2 of the drawing, the movement is supported in an integral plastic frame member 1 molded as an single piece and having an intricate shape of high precision.
Fig. 1 is a plan view from the top (dial side) and Fig. 2 is a plan view from the bottom (back side). Since the elements are assembled from both sides of the frame 1, it is convenient to refer to Figs. 1 and 2 together.
A lead frame assembly 2 shown in Figs. 1 & 2 includes a driving circuit preferably in the form of an integrated circuit 3. The integrated circuit 3 is encapsulated in an insulating material along with embedded ends of projecting electrical contact members used for attachment to the quartz crystal, the stepping motor drive coil, and the power supply.
The integrated circuit 3, by means not material to the present invention, provides a periodic drive pulse to a stepping motor shown generally as 4. Stepping motor 4 best seen in Fig.
comprises a flat U-shaped stator and core piece 5, a coil 6 and J~ J ~j ~ PI-1285 a magnetic bridge 7. The stator member 5 defines an opening 8 surrounding a stepping motor rotor 9.
The lead frame 2 may be manufactured by processes described in U.S. Patent 4,391,531 to Yokota, et al, issued July 5, 1983, and assigned to the present assignee, which is incorporated herein by reference. The stepping motor 4 may be constructed in accordance with the stepping motor shown in U.S.
Patent 4,720,644, issued to Sedlak on January 19, 1988, and assigned to the present assignee, and incorporated herein by reference.
The energy cell (not shown) is preferably a relatively thin, 3 volt lithium cell of large diameter (i.e., covering a major portion of the back side of the movement) and fits in a recess 10 molded into the integral plastic frame member 1 on the back side opposite the dial. Negative and positive spring contact members 11, 12 as integral parts of the lead frame 2, make electrical contact with the energy cell and supply to the integrated circuit 3. An additional holding spring 13 is fixed to frame 1 by ultrasonic deformation of projecting plastic frame posts la, lb. Holding spring 13 includes a flange 13a making contact with the energy cell and a flange 13b (Fig. 2) serving as a spring detent for a slidable and rotatable timesetting stem member 14, with an attached setting gear pinion 33.
2 ~ 2 ~
Referring now to Fig. 3 of the drawing, the gear train arrangement and bearing support which is a main feature of the present invention will be more clearly seen. Fig. 3 is a cross-section elevation view developed along the zig-zag line III-III of Fig. 1 and does not show the negative contact member 11 of the lead frame 2. Stepping motor rotor 9 comprises a bipolar doughnut-shaped permanent magnet 15 which is overmolded by plastic material adapted to support the magnet as well as to form integral journals 16, 17 and diametrically disposed drive pins 18, which serve as a pinion. Journal 16 is rotatably supported in a bore in the center of a brass bushing 19 which is affi~ed to stator member 5. Journal 17 is rotatably supported in a bore in frame 1. The stepping motor assembly comprising coil 6, stator 5, rotor 9 and bushing 19 is preferably premounted in frame 1 as a subassembly later for addition of the gear train components, utilizing pegs, integral with frame 1, such as those shown in Fig. 1 as lc, ld, le, which extend through holes in the stator 5 and magnetic bridge 7 and are deformed on the ends by ultrasonic welding. The frame may also be deformed as shown at ld to lock the stepping motor in place.
Driving pins 18 on the stepping motor rotor 9 are disposed to alternately engage ogival teeth on the periphery of a toothed center wheel 20. Wheel 20 is frictionally engaged with a slip fit on the end of a center spindle 21 which includes an integral center pinion 22. The friction surface for the slip fit may be provided either between the spindle 21 and the center wheel 20, or between the adjacent faces of the center wheel 20 and center pinion 22.
Center spindle 21 is rotatably supported in a center bore running through the center of a cylindrical stub 23 extending above frame 1 on the dial side of the timepiece. The timepiece dial indicated at 24 is held (by means not material to the present invention) on top of frame 1 when the movement is assembled in the case. Cylindrical stub 23 extends through an aperture 24a in the dial 24 and extends above the dial.
Center spindle 21 is rotatably supported in frame 1 by a larger diameter journal 25 in the frame proper and a smaller diameter journal 26 in the end of stub 23. An extension 21a on spindle 21 projects beyond journal 26 and extends beyond the end of stub 23. A separate center bushing 27 is press-fit on the extension 21a of spindle 21. The bushing 27, spindle 21, pinion 22 and center wheel 20, together make up a first rotating assembly which is rot:atably supported in the frame on bearing journals 25, 26. Bushing 27 serves several purposes.
First, it holds the first assembly in the frame while controlling axial clearances (end-shake). Secondly, it is adapted on its outer surface to hold a minute hand 28. Hand 28 is pressed over the outside of bushing 27, which may be splined or simply a friction fit. Thirdly, the bushing 27 has a flange 27a that holds the hour wheel in place and controls hour wheel "end-shake", as will be explained.
A second rotating assembly comprises a minute wheel 29 pressed on the end of a spindle 30. The spindle 30 is fabricated as an integral member with a minute pinion 31.
Spindle 30 is journaled in a bore passing through frame 1.
Minute wheel 29 has ordinary spur gear teeth engaging those of center pinion 22 and also includes an a~ially extending set of beveled "crown" teeth 32 used for time setting. The crown teeth may be selectively engaged by the setting gear pinion 33 when the stem 14 is axially withdrawn.
Lastly, an hour wheel 34 is rotatably journalled in the frame by means of a collar 35 which forms close rotating clearances with the exterior of the stub 23. Hour wheel 33 engages with and is driven by teeth on the minute pinion 31.
The exterior of the collar 35 is adapted to hold an hour hand 36, using splines or friction fit.
Flange 27a of bushing 27 engages the end of stub 23 and also projects radially beyond it so as to engage also the ~ Q ~
end of collar 35 on the hour whee:L. Therefore, the bushing flange serves to limit axial movement of the first rotating assembly and also to limit axial movement of the hour wheel.
Axial movement of these two rotating members in the opposite direction is, in both cases, limited by the frame l.
MODIFICATION
An alternate arrangement is shown in Fig. 4 which is the preferred embodiment, because of its simplicity. Only the portions of the movement are shown which are necessary for an understanding, the rest of the parts being identical to those in Figs. 1-3.
Frame member 37 includes an integral cylindrical stub 38 defining a center bore 39 coaxial therewith and rotatably journaling a first assembly 40. Assembly 40 includes a spindle 41 with asially spaced first journal 42 in the frame and second journal 43 in the stub. Bushing means 44 is a member similar to bushing 27 shown in Fig. 3, but made integral with spindle 41. Bushing means 44 includes a flange 45 abutting the end of stub 38 and also extending radially beyond the diameter of stub 38. An hour wheel 46 with collar 47 is rotatably journaled on the stub and held in place by flange 45.
A center pinion 48 is pressfit onto spindle 41 after it has been inserted in bore 39, and center wheel 49 is then fitted onto spindle 41. Frictional slip fit of the center wheel on the first assembly may be provided either between spindle and center wheel or between center pinion and center wheel faces.
OPERATION OF THE INVENTION
The movement shown in Figs. 1-3 is assembled by first assembling and attaching the stepping motor 4 to plastic frame 1. Then the hour wheel 34 and minute pinion 30 are placed on the dial side; minute wheel 29 and center wheel assembly added from the back side; and lastly the center bushing is fixed to the center spindle extension 21a on the dial side. After the gear train is assembled, the dial 24 and hands 28, 36 are added in the usual manner during assembly into the case. In the Fig.
4 embodiment, the integral bushing and spindle are inserted from the dial side once the hour wheel is in place. The center pinion and center wheel are added from the back side.
When the integrated circuit 3 is powered by the energy cell, drive pulses rotate the driving pins 18 one-half revolution once each minute to advance center wheel 20, advancing first rotating assembly including the center spindle PI-12~5 21 and the minute hand Z8. Speed reduction to drive the hour hand is accomplished by the second rotating assembly, comprising minute pinion 31, spindle 30 and minute wheel 29.
Advancement of ~inute wheel 29, when driven by pinion 22, rotates hour wheel 34 and the attached hour hand 35.
When it is desired to reset the timepiece, stem 14 is a~ially withdrawn so that setting pinion gear 33 engages crown teeth 32. When time setting takes place, center wheel 20 is locked in place by the reactive torque of the stepping motor and slips on spindle 21 by virtue of the friction fit to allow the spindle to turn.
The foregoing improvement allows a very simple and thin physical arrangement of the gear train suitable for a large diameter energy cell which covers the major portion of the back side of the plastic frame. The use of a frame stub 23 with central bore serving as a bearing for two rotating members and using the bushing to control end shake of both rotating members provides a simple movement construction.
While there has been described what is considered to be the preferred embodiment of the invention, other modifications will become apparent to those skilled in the art. For e~ample, while the stub 23 in its preferred mode is an integral part of the frame, it could also be a separate fixed post staked or otherwise fit into the frame in the manner shown in aforementioned United States Patent No. 4,720,644.
Other modifications will become apparent to those ski led in the art and it is desired to secure in the appended claims all such modifications as fall witllin the true spirit and scope of the invention.
SUMMARY OF THE INVENTION
Briefly stated, the invention comprises an improved movement for a timepiece of the type having an hour hand, a minute hand, driving circuit adapted for connecting to an energy cell, a stepping motor,- a plastic frame member having a dial side and a back side, and adapted to hold said stepping motor, and a gear train supported by said frame member and arranged to drive the hour hand and minute hand from said stepping motor, said gear train comprising a first assembly of a center wheel and center pinion with said center wheel driven directly by the stepping motor, a second assembly of a minute wheel and minute pinion with said minute wheel driven directly by said center pinion, and an hour wheel driven directly by said minute pinion, wherein the improvement comprises a stub extending from the front side of said frame, said stub defining a center bore extending through the frame and stub, a spindle extending through said center bore and rotatably supporting said first assembly in the frame, said spindle including a bushing on the f ront side of said frame adapted to hold the minute hand and to control axial clearance for the first assembly, said center wheel frictionally engaged with said spindle on the back side of said frame, and a collar fixed to said hour wheel and adapted to rotatably support said hour wheel on the stub, said collar further adapted to hold the hour 2 i~
hand. The bushing may be separate from the spindle, but preferably is integral therewith.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figs. 1 and 2 of the drawing, the movement is supported in an integral plastic frame member 1 molded as an single piece and having an intricate shape of high precision.
Fig. 1 is a plan view from the top (dial side) and Fig. 2 is a plan view from the bottom (back side). Since the elements are assembled from both sides of the frame 1, it is convenient to refer to Figs. 1 and 2 together.
A lead frame assembly 2 shown in Figs. 1 & 2 includes a driving circuit preferably in the form of an integrated circuit 3. The integrated circuit 3 is encapsulated in an insulating material along with embedded ends of projecting electrical contact members used for attachment to the quartz crystal, the stepping motor drive coil, and the power supply.
The integrated circuit 3, by means not material to the present invention, provides a periodic drive pulse to a stepping motor shown generally as 4. Stepping motor 4 best seen in Fig.
comprises a flat U-shaped stator and core piece 5, a coil 6 and J~ J ~j ~ PI-1285 a magnetic bridge 7. The stator member 5 defines an opening 8 surrounding a stepping motor rotor 9.
The lead frame 2 may be manufactured by processes described in U.S. Patent 4,391,531 to Yokota, et al, issued July 5, 1983, and assigned to the present assignee, which is incorporated herein by reference. The stepping motor 4 may be constructed in accordance with the stepping motor shown in U.S.
Patent 4,720,644, issued to Sedlak on January 19, 1988, and assigned to the present assignee, and incorporated herein by reference.
The energy cell (not shown) is preferably a relatively thin, 3 volt lithium cell of large diameter (i.e., covering a major portion of the back side of the movement) and fits in a recess 10 molded into the integral plastic frame member 1 on the back side opposite the dial. Negative and positive spring contact members 11, 12 as integral parts of the lead frame 2, make electrical contact with the energy cell and supply to the integrated circuit 3. An additional holding spring 13 is fixed to frame 1 by ultrasonic deformation of projecting plastic frame posts la, lb. Holding spring 13 includes a flange 13a making contact with the energy cell and a flange 13b (Fig. 2) serving as a spring detent for a slidable and rotatable timesetting stem member 14, with an attached setting gear pinion 33.
2 ~ 2 ~
Referring now to Fig. 3 of the drawing, the gear train arrangement and bearing support which is a main feature of the present invention will be more clearly seen. Fig. 3 is a cross-section elevation view developed along the zig-zag line III-III of Fig. 1 and does not show the negative contact member 11 of the lead frame 2. Stepping motor rotor 9 comprises a bipolar doughnut-shaped permanent magnet 15 which is overmolded by plastic material adapted to support the magnet as well as to form integral journals 16, 17 and diametrically disposed drive pins 18, which serve as a pinion. Journal 16 is rotatably supported in a bore in the center of a brass bushing 19 which is affi~ed to stator member 5. Journal 17 is rotatably supported in a bore in frame 1. The stepping motor assembly comprising coil 6, stator 5, rotor 9 and bushing 19 is preferably premounted in frame 1 as a subassembly later for addition of the gear train components, utilizing pegs, integral with frame 1, such as those shown in Fig. 1 as lc, ld, le, which extend through holes in the stator 5 and magnetic bridge 7 and are deformed on the ends by ultrasonic welding. The frame may also be deformed as shown at ld to lock the stepping motor in place.
Driving pins 18 on the stepping motor rotor 9 are disposed to alternately engage ogival teeth on the periphery of a toothed center wheel 20. Wheel 20 is frictionally engaged with a slip fit on the end of a center spindle 21 which includes an integral center pinion 22. The friction surface for the slip fit may be provided either between the spindle 21 and the center wheel 20, or between the adjacent faces of the center wheel 20 and center pinion 22.
Center spindle 21 is rotatably supported in a center bore running through the center of a cylindrical stub 23 extending above frame 1 on the dial side of the timepiece. The timepiece dial indicated at 24 is held (by means not material to the present invention) on top of frame 1 when the movement is assembled in the case. Cylindrical stub 23 extends through an aperture 24a in the dial 24 and extends above the dial.
Center spindle 21 is rotatably supported in frame 1 by a larger diameter journal 25 in the frame proper and a smaller diameter journal 26 in the end of stub 23. An extension 21a on spindle 21 projects beyond journal 26 and extends beyond the end of stub 23. A separate center bushing 27 is press-fit on the extension 21a of spindle 21. The bushing 27, spindle 21, pinion 22 and center wheel 20, together make up a first rotating assembly which is rot:atably supported in the frame on bearing journals 25, 26. Bushing 27 serves several purposes.
First, it holds the first assembly in the frame while controlling axial clearances (end-shake). Secondly, it is adapted on its outer surface to hold a minute hand 28. Hand 28 is pressed over the outside of bushing 27, which may be splined or simply a friction fit. Thirdly, the bushing 27 has a flange 27a that holds the hour wheel in place and controls hour wheel "end-shake", as will be explained.
A second rotating assembly comprises a minute wheel 29 pressed on the end of a spindle 30. The spindle 30 is fabricated as an integral member with a minute pinion 31.
Spindle 30 is journaled in a bore passing through frame 1.
Minute wheel 29 has ordinary spur gear teeth engaging those of center pinion 22 and also includes an a~ially extending set of beveled "crown" teeth 32 used for time setting. The crown teeth may be selectively engaged by the setting gear pinion 33 when the stem 14 is axially withdrawn.
Lastly, an hour wheel 34 is rotatably journalled in the frame by means of a collar 35 which forms close rotating clearances with the exterior of the stub 23. Hour wheel 33 engages with and is driven by teeth on the minute pinion 31.
The exterior of the collar 35 is adapted to hold an hour hand 36, using splines or friction fit.
Flange 27a of bushing 27 engages the end of stub 23 and also projects radially beyond it so as to engage also the ~ Q ~
end of collar 35 on the hour whee:L. Therefore, the bushing flange serves to limit axial movement of the first rotating assembly and also to limit axial movement of the hour wheel.
Axial movement of these two rotating members in the opposite direction is, in both cases, limited by the frame l.
MODIFICATION
An alternate arrangement is shown in Fig. 4 which is the preferred embodiment, because of its simplicity. Only the portions of the movement are shown which are necessary for an understanding, the rest of the parts being identical to those in Figs. 1-3.
Frame member 37 includes an integral cylindrical stub 38 defining a center bore 39 coaxial therewith and rotatably journaling a first assembly 40. Assembly 40 includes a spindle 41 with asially spaced first journal 42 in the frame and second journal 43 in the stub. Bushing means 44 is a member similar to bushing 27 shown in Fig. 3, but made integral with spindle 41. Bushing means 44 includes a flange 45 abutting the end of stub 38 and also extending radially beyond the diameter of stub 38. An hour wheel 46 with collar 47 is rotatably journaled on the stub and held in place by flange 45.
A center pinion 48 is pressfit onto spindle 41 after it has been inserted in bore 39, and center wheel 49 is then fitted onto spindle 41. Frictional slip fit of the center wheel on the first assembly may be provided either between spindle and center wheel or between center pinion and center wheel faces.
OPERATION OF THE INVENTION
The movement shown in Figs. 1-3 is assembled by first assembling and attaching the stepping motor 4 to plastic frame 1. Then the hour wheel 34 and minute pinion 30 are placed on the dial side; minute wheel 29 and center wheel assembly added from the back side; and lastly the center bushing is fixed to the center spindle extension 21a on the dial side. After the gear train is assembled, the dial 24 and hands 28, 36 are added in the usual manner during assembly into the case. In the Fig.
4 embodiment, the integral bushing and spindle are inserted from the dial side once the hour wheel is in place. The center pinion and center wheel are added from the back side.
When the integrated circuit 3 is powered by the energy cell, drive pulses rotate the driving pins 18 one-half revolution once each minute to advance center wheel 20, advancing first rotating assembly including the center spindle PI-12~5 21 and the minute hand Z8. Speed reduction to drive the hour hand is accomplished by the second rotating assembly, comprising minute pinion 31, spindle 30 and minute wheel 29.
Advancement of ~inute wheel 29, when driven by pinion 22, rotates hour wheel 34 and the attached hour hand 35.
When it is desired to reset the timepiece, stem 14 is a~ially withdrawn so that setting pinion gear 33 engages crown teeth 32. When time setting takes place, center wheel 20 is locked in place by the reactive torque of the stepping motor and slips on spindle 21 by virtue of the friction fit to allow the spindle to turn.
The foregoing improvement allows a very simple and thin physical arrangement of the gear train suitable for a large diameter energy cell which covers the major portion of the back side of the plastic frame. The use of a frame stub 23 with central bore serving as a bearing for two rotating members and using the bushing to control end shake of both rotating members provides a simple movement construction.
While there has been described what is considered to be the preferred embodiment of the invention, other modifications will become apparent to those skilled in the art. For e~ample, while the stub 23 in its preferred mode is an integral part of the frame, it could also be a separate fixed post staked or otherwise fit into the frame in the manner shown in aforementioned United States Patent No. 4,720,644.
Other modifications will become apparent to those ski led in the art and it is desired to secure in the appended claims all such modifications as fall witllin the true spirit and scope of the invention.
Claims (11)
1. Improved movement for a timepiece having a hour hand, a minute hand, a driving circuit, a stepping motor, a plastic frame member having a dial side and a back side adapted to hold said stepping motor, and a gear train supported by said frame member and arranged to drive the hour hand and minute hand from said stepping motor, said gear train comprising a first assembly of a center wheel and center pinion with said center wheel driven directly by the stepping motor, a second assembly of a minute wheel and minute pinion with said minute wheel driven directly by said center pinion, and an hour wheel driven directly by said minute pinion, wherein the improvement comprises:
a stub extending from the front side of said frame, said frame defining a center bore extending through the frame and stub, a spindle extending through said center bore and rotatably supporting said first assembly in the frame, said spindle including a bushing engaging the end of said stub on the front side of said frame and adapted to hold the minute hand, and a collar fixed to said hour wheel and adapted to rotatably support said hour wheel on the stub, said collar further adapted to hold the hour hand.
a stub extending from the front side of said frame, said frame defining a center bore extending through the frame and stub, a spindle extending through said center bore and rotatably supporting said first assembly in the frame, said spindle including a bushing engaging the end of said stub on the front side of said frame and adapted to hold the minute hand, and a collar fixed to said hour wheel and adapted to rotatably support said hour wheel on the stub, said collar further adapted to hold the hour hand.
2. The improvement according to Claim 1, wherein said frame member is a single plastic molding, and wherein said stub is an integral part thereof.
3. The improvement according to Claim 1, wherein said bushing is an integral part of said spindle.
4. The improvement according to Claim 1, wherein said spindle includes a first journal rotatably disposed in the frame proper and a second axially spaced journal rotatably disposed in said stub.
5. The improvement according to Claim 1, wherein said spindle includes an extension arranged to extend beyond the end of said stub, and wherein said bushing is fixed to said spindle extension and includes flange means cooperating with the end of said stub to control the axial clearances of said first assembly with the frame member.
6. The improvement according to Claim 1, wherein said second assembly includes a pinion disposed on one side of said frame drivingly engaging said hour wheel, a second spindle extending through and beyond said frame, and a minute wheel affixed to the end of said spindle and engaging said center pinion to be driven thereby.
7. The improvement according to Claim 1, wherein said bushing includes flange means extending radially beyond said stub and adapted to cooperate with said collar to retain said hour wheel on said stub.
8. The improvement according to Claim 1, further including a setting stem axially slidable and rotatably supported within said frame and having a setting gear pinion thereon, and wherein said minute wheel includes a set of crown teeth adapted for engagement with said setting gear pinion, and wherein said center wheel on the first assembly is frictionally engaged therewith so as to slip on the spindle when the setting gear pinion engages the crown teeth, whereby said setting stem may rotate the minute wheel.
9. Improved movement for a timepiece having an hour hand, a minute hand, a driving circuit, a stepping motor, a plastic frame member having a dial side and a back side adapted to hold said stepping motor, said frame member adapted to hold a large diameter energy cell covering a major portion of the back side of said frame member, and a gear train arranged to drive the hour hand and minute hand from said stepping motor, said gear train comprising a first assembly of a center wheel and center pinion, said stepping motor having a rotor with two pins and said center wheel having ogival teeth driven directly by the stepping motor rotor pins, a second assembly of a minute wheel and minute pinion with said minute wheel driven directly by said center pinion, and an hour wheel driven directly by said minute pinion, wherein the improvement comprises:
a cylindrical stub integral with and extending from the dial side of said frame, said stub defining a center bore extending through the frame and stub co-axial with said stub, a spindle extending through said center bore and having a first journal disposed in the frame proper and a second journal axially spaced therefrom and disposed in the end of said cylindrical stub, said first and second journals rotatably supporting said first assembly in the frame, said spindle having an extension extending beyond said second journal a collar fixed to said hour wheel and adapted to rotatably support the hour wheel on said cylindrical stub, said collar being adapted to hold the hour hand, and center bushing means on said spindle extension said center bushing means having a first flange portion cooperating with the cylindrical stub to hold the first assembly in place, and further cooperating with said collar to hold the hour wheel on said stub, said center bushing means further being adapted to hold the minute hand.
a cylindrical stub integral with and extending from the dial side of said frame, said stub defining a center bore extending through the frame and stub co-axial with said stub, a spindle extending through said center bore and having a first journal disposed in the frame proper and a second journal axially spaced therefrom and disposed in the end of said cylindrical stub, said first and second journals rotatably supporting said first assembly in the frame, said spindle having an extension extending beyond said second journal a collar fixed to said hour wheel and adapted to rotatably support the hour wheel on said cylindrical stub, said collar being adapted to hold the hour hand, and center bushing means on said spindle extension said center bushing means having a first flange portion cooperating with the cylindrical stub to hold the first assembly in place, and further cooperating with said collar to hold the hour wheel on said stub, said center bushing means further being adapted to hold the minute hand.
10. The improvement according to Claim 9 wherein said center bushing means is a separate center bushing affixed to said spindle extension.
11. The improvement according to Claim 9 wherein said center bushing means is a center bushing integral with said spindle extension.
6298n
6298n
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58023390A | 1990-09-10 | 1990-09-10 | |
| US580,233 | 1990-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2048826A1 true CA2048826A1 (en) | 1992-03-11 |
Family
ID=24320253
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2048826 Abandoned CA2048826A1 (en) | 1990-09-10 | 1991-08-08 | Two hand movement for timepiece with stepping motor |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2048826A1 (en) |
| FR (1) | FR2666665A1 (en) |
| GB (1) | GB9113292D0 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3495897B1 (en) | 2017-12-08 | 2020-08-12 | ETA SA Manufacture Horlogère Suisse | Timepiece comprising an electric motor secured to an attachment plate |
-
1991
- 1991-06-19 GB GB919113292A patent/GB9113292D0/en active Pending
- 1991-08-08 CA CA 2048826 patent/CA2048826A1/en not_active Abandoned
- 1991-09-10 FR FR9111163A patent/FR2666665A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2666665A1 (en) | 1992-03-13 |
| GB9113292D0 (en) | 1991-08-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |