Motor-driven movement for timepiece

Motor-driven movement for timepieces wherein stator block core is formed in ring-shape with a magnetic material of a rounded bar, magnetic poles formed at both core ends are disposed as directed radially inward of the core and rotary shaft of minute hand wheel of output gear train meshing with a rotor disposed between the poles is radially displaced from the center of the core to the side opposite the magnetic poles, whereby internal space of the ring-shaped core having a coil wound thereon is efficiently utilized for arranging all internal components substantially within dimensions of the coil and minimizing the entire size of the movement.

This invention relates generally to motor-driven movements for timepieces 
and, more particularly, to improvements in the motor-driven movement for 
such timepieces as clocks wherein component members are compactly 
arranged. 
For the motor-driven movements for use in such clocks as wall-hung clocks, 
table-clocks and the like, it has been required to make them thin and 
small, that is, to be small in the total volume and, thus, to have general 
usages so that they will be applicable not only larger clocks but also to 
smaller clocks, even including considerably thin wall-hung clocks. For 
this purpose, it has been suggested to form a stator which is a main 
component of electric motor in a ring shape and to dispose a rotor 
rotatably between opposed magnetic poles at both ends of the ring-shaped 
stator and output gear train cooperating with the motor within the 
interior space of the ring, so as to render the entire volume to be 
smaller. 
In this arrangement, however, the rotor is arranged only between the 
magnetic poles which are facing each other in the peripheral direction of 
the ring-shaped stator without any measure for minimizing their 
dimensions, an output shaft of the output gear train is positioned at the 
center of the ring, and the space remained unused within the ring shaped 
stator becomes so large that the volume minimization has been inefficient. 
A primary object of the present invention is, therefore, to provide a 
motor-driven movement for timepieces which is thin and small so as to be 
capable of minimizing its occupying space in the clock or the like to 
which the movement is applied and is high in the general uses. 
A related object of the present invention is to provide a motor-driven 
movement for timepieces wherein the motor, circuit parts accompanying the 
motor and output gear train are efficiently arranged within the inner 
space of a ring-shaped stator to render the entire volume smaller. 
A further object of the present invention is to provide a motor-driven 
movement for timepieces wherein magnetic poles at both ends of a 
ring-shaped stator are opposed to each other in a radial direction of the 
ring, a rotor is arranged between such magnetic poles and the output shaft 
of output gear train engaged with the rotor is displaced radially to the 
side opposite the rotor with respect to the center of the ring to thereby 
minimize the volume. 
Another object of the present invention is to provide a motor-driven 
movement for timepieces wherein a bar-shaped magnetic material having 
circular cross-section and constant thickness is used for the stator core 
forming an electric motor so that, even if the volume is made small, easy 
assembling ability will be high, and the stator is favorably resiliently 
supported at the respective ends so that, even if the volume is made 
small, pull-out terminals of stator coil will engage with associated 
circuit parts under a favorable contact pressure. 
A still another object of the present invention is to provide a 
motor-driven movement for timepieces wherein, even if the volume is made 
small, the stator is favorably held at the respective ends and, at the 
same time, the rotor positioning can be smoothly performed.

While the present invention shall now be explained in the followings with 
reference to the preferred embodiment shown in the accompanying drawings, 
it should be understood that the present invention is not to be limited 
only to the particular embodiment shown but is to include all 
modifications, alterations and equivalent arrangement possible within the 
scope of appended claims. 
Prior to the descriptions of the present invention, first, a well known 
movement disclosed in U.S. Pat. No. 4,141,210 to Flaig shall be explained 
with reference to FIG. 1. In this movement, a flat core MC having a 
certain width is formed to be ring-shaped and a coil L is wound on the 
core MC through a coil supporter CS to form a stator S of an electric 
motor. Further in this case, respective end portions of the core MC are 
expanded to be substantially symmetrical with each other so as to be 
favorable magnetic poles and are semi-circularly cut to define a 
substantially circular space as opposed to each other. A rotor R is 
disposed in the circular space so that, when an electric current is passed 
through the coil L, the rotor R will be magnetically driven to rotate 
within the circular space by means of a proper driving circuit (not shown) 
as has been well known and a clock gear train (not shown) will be thereby 
operated. 
In the above described known formation, an output gear train and the like 
can be arranged within the ring-shaped stator so that the volume can be 
made small to a certain degree. However, as the flat stator core is used, 
the coil wound thereon to a larger amount for achieving a larger torque 
will render the space within the stator to be smaller and the contour to 
be still larger, and there has been a defect that the entire volume can 
not be made effectively smaller. That is, the more attempt is made to 
reduce the volume, the more space factor will be restricted to render the 
torque to be rather smaller so that there has been a defect that the 
general usage will become low. Further, while the output gear train can be 
contained in the interior space of the ring-shaped stator, the output 
shaft of the output gear train is usually positioned in the center of the 
ring, the degree of utilizing the interior space for other elements is low 
and the entire volume often has not been made small enough. In particular, 
as the end portions of the stator core are expanded to have a larger pole 
surface, the coil must be wound after the coil supporter is fitted onto 
the core, so that the coil winding must be made along the ring shape and 
the workability will be so low that there has been a problem in the 
mass-productivity. The present invention is suggested to solve the above 
described various problems. 
Referring now to FIGS. 2 to 20, a motor-driven movement 10 according to the 
present invention comprises a stator block 11 and rotor 12 which are 
forming an electric motor, lower and upper circular casings 13 and 14 
which can fit to each other so as to define between them a housing space, 
an output gear train 15 engaged with hour and minute hands and an electric 
circuit block 16 including respective circuit parts for the electric 
motor. 
According to an aspect of the present invention, particularly with 
reference to FIG. 2, a round-sectioned and bar-shaped magnetic material 
of, for example, permalloy or electromagnetic soft iron is used for a core 
21 of the stator block 11 to improve the space factor and to expand the 
housing space for respective required components. The core 21 is curved to 
be substantially ring-shaped in the contour, one end portion 22 forming 
one magnetic pole extends in the peripheral direction, while the other end 
portion 23 forming the other magnetic pole is bent to be substantially 
L-shaped as directed inward in the radial direction to have its bent 
portion of the L-shape directed toward the center of ring-shaped contour. 
Further, a coil 25 is wound on the core 21 through a hollow coil supporter 
24 except for the end portions forming the magnetic poles. 
In manufacturing the coil 25, particularly with reference to FIG. 5, a 
spiral shaping pattern 26 preferably of a metal bar having substantially 
the same diameter as the core 21 is used. In this case, initially the coil 
25 is wound on the coil supporter 24 which is straight but bendable, so as 
to be straight in the entirety, then a straight part 27 at one end of the 
shaping pattern 26 is inserted through the axial hollow part of the coil 
supporter 24, and the coil 25 with the supporter 24 is further gradually 
moved along the spiral line of the pattern 26. The other end 28 of the 
shaping pattern 26 is curved with substantially the same curvature as the 
ring-shaped core 21, and the coil 25 wound on the coil supporter 24 
reaching this position to be thus curved into desired shape of the 
ring-shape is impregnated with an insulating varnish or the like which is 
thereafter solidified. Therefore, the coil supporter and coil will be 
shaped so that they can be smoothly mounted from the one end portion 22 
extending in the peripheral direction of the core 21 toward the other end 
portion 23 bent to be L-shaped. Further, the coil supporter 24 employed in 
the present invention may be of a single member as shown in FIG. 2 or may 
be divided into a plurality of portions as shown in FIGS. 4 and 5. 
Further, such disk-shaped coil-end plates 29 and 30 as shown in FIGS. 6 and 
7 are fitted to the boundaries between the coil winding zone on the core 
21 and the magnetic pole zones at the respective ends, and slits 32 and 33 
extending in the horizontal direction symmetrically with respect to a core 
inserting hole 31 are made in the coil end plates 29 and 30. A lead 34 of 
the coil 25 is connected to a coil connecting terminal 35 through which 
the core 21 is passed. The coil connecting terminal 35 itself is formed to 
be U-shaped and has contact legs 38 and 39 which are respectively opened 
as directed outward to be separated from each other while being provided 
with contact points 36 and 37 and projected in the same extending 
direction as the core 21 through the slits 32 and 33 of the coil-end 
plates 29 and 30. In this case, as the contact legs 38 and 39 are opened 
outward to be thus inclined in the directions separating from each other, 
a favorable electric connection can be obtained as detailed later. While 
FIGS. 6 and 7 do not show the supporter 24, the coil-end plates 29 and 30 
can be formed integral with the coil supporter 24, if so desired. The coil 
supporter 24 may be in such member as an insulative paper or the like. 
The rotor 12 of the motor comprises an axial shaft 42 passing through a 
disk body 41 which is magnetized to have two opposite magnetic poles on 
both sides of the vertical plane including the axis of the shaft 42, and 
an output pinion 43 provided integrally at an end of the shaft 42. 
According to another aspect of the present invention, arrangements of the 
magnetic poles of the stator block 11 as well as the rotor 12 are so made 
that they are favorably held in position at a high precision and a 
reliable stepwise operation of the motor can be assured. Particularly with 
reference to FIGS. 2, 8, 9 and 11, an annular recess 51 having a curved 
bottom surface is formed in the peripheral part of the lower casing 13 so 
as to extend in the peripheral direction of the casing substantially for 
the same length as the coil winding zone of the stator block 11. Further, 
a sector-shaped base 52 is provided in the lower casing 13 so as to 
integrally extend therein at a position between both ends of the annular 
recess 51, so that the apex of the sector-shape is directed toward the 
center of the lower casing 13 and the arcuate part is positioned to 
contact the inner side in the radial direction of the core 21 lying in the 
peripheral direction, and a circular recess 53 of a diameter larger than 
the outermost diameter of the rotor 12 is provided substantially in the 
center of the base 52. Inward projecting ribs 54 are provided on the 
peripheral wall of the recess 53 specifically on the apex side of the base 
52, for preventing any excess inclination of the rotor 12 as disposed in 
the circular recess 53. In other words, even when the circular rccess 53 
is formed to be of a diameter well larger than the outermost diameter of 
the rotor 12, the rotor 12 will be prevented by the projecting ribs 54 
from inclining excessively. On the other hand, pressing projections 55 are 
provided to project inward in the radial direction on the inside surface 
of the outermost peripheral part of the lower casing 13. The one end 
portion 22 extending in the peripheral direction and forming one magnetic 
pole of the core 21 is positioned between the arcuate part of the sector 
base 52 and the pressing projections 55. Further, near the respective 
radial sides of the sector base 52 of the lower casing 13, pressing 
projections 56 and 57 are provided to project as separated from the base 
52 by a distance substantially corresponding to the diameter of the core 
21, so that the other L-shaped end portion 23 forming the other magnetic 
pole of the core 21 will be positioned between the base 52 and the 
respective projections 56 and 57. 
In the present instance, the dimensions and positions of the sector base 52 
in its outline, circular recess 53, projecting ribs 54 and pressing 
projections 55, 56 and 57 are so made that, when the respective end 
portions 22 and 23 of the core 21 and rotor 12 are arranged in the 
predetermined positions, particularly as shown in FIG. 8, the distance "a" 
between outer tip end leg part 23a of the L-shaped end portion 23 of the 
core 21 and the rotor body 41, the distance "b" between inner continuing 
leg part 23b also of the L-shaped end portion 23 of the core 21 and the 
rotor body 41 and the distance "c" between the one end portion 22 of the 
core 21 and the rotor body 41 will be in such relation that a&lt;b&lt;c. 
In the lower casing 13, as will be clear specifically in view of FIG. 3, a 
recessed part 59 for receiving a manually rotating wheel 58 and another 
recessed part 61 for receiving a resetting button 60 are formed on the 
exterior side of the lower casing 13. Further in the lower casing 13, as 
described later, projections 62 and 63 having screw holes contributing to 
the fitting of the casing 13 to the upper casing 14 are provided, and 
projections 64 and 65 having screw holes contributing to a fixation of the 
circuit block 16 and a pin 66 are provided to project on the upper surface 
of the base 52. A shaft bearing hole and output gear bearing part are 
formed respectively in the center of the circular recess 53 and recessed 
part 59. 
The circuit block 16 is provided to be mountable in the lower casing 13 and 
on the stator block 11. The block 16 comprises a printed base plate 71 
having respective such required circuit parts for controlling the motor as 
being known per se. Further, with reference to FIG. 12, in the controlling 
circuit, an inverter 75 and resistance 76 are connected in parallel to a 
series circuit of a capacitor 72, quartz vibrator 73 and trimmer capacitor 
74, and a frequency dividing circuit 77, wave-form shaping circuit 78 and 
driving circuit 79 are connected sequentially to the output end of the 
inverter 75. In this case, the circuit from the inverter 75 to the driving 
circuit can be also made in one chip to be an integrated circuit. The 
output terminals 79a and 79b of the driving circuit 79 are connected to 
both ends of the coil 25 of the stator block 11. On the other hand, the 
current source voltage of the circuit block 16 is obtained from a 
secondary battery charged by a later described solar battery. Such output 
wave-form as shown in FIG. 13 is given, in particular, by the action of 
the quartz vibrator 73, whereby the rotor 12 is caused to perform its 1/2 
rotation per 30 seconds through the two magnetic poles of the stator block 
11. 
Referring in particular to FIGS. 2 and 3, the printed base plate 71 is 
formed to be of a dimension in its contour smaller than the inside 
diameter of the coil 25, and a large opening 80 substantially 
key-hole-shaped is made so that the output gear 15 can rotate without 
contacting the printed base plate 71. Further, the printed base plate 71 
is provided with a resetting terminal (not shown) with which the resetting 
button 60 fitted to the lower casing 13 is engageable when the button is 
depressed so that a current will flow in the circuit for resetting the 
count of seconds. A fixing part 81 is expanded as directed outward in the 
radial direction at a part of the periphery of the printed base plate 71. 
A hole 82 is provided substantially in the center of the fixing part 81 
for allowing a pin 66 on the base 52 of the lower casing 13 to be engaged 
therein. Further fitting holes 83 and 84 provided as separated from each 
other in the peripheral direction with respect to the hole 82 are aligned 
respectively with the projections 64 and 65 on the base 52 and, therefore, 
the printed base plate 71 can be fixed onto the base 52 of the lower 
casing 13 at the fixing part 81 by means of screws 85 and 86. 
When the fixing part 81 of the printed base plate 71 is thus fixed to the 
lower casing 13, particularly as shown in FIG. 7, the contact leg 39 is 
urged into contact with the inner surface of the lower casing 13 while 
being displaced inward so that the other contact leg 38 will be urged into 
contact with the printed base plate 71 under a sufficient contact pressure 
to be directly positively connected with the coil 25 and conducting part 
of the printed base plate 71 or, preferably, with output terminals 79a and 
79b of the driving circuit 79. Further, as described later, pull-out 
terminals 87 and 88 provided to the printed base plate 71 are connected to 
the secondary battery provided in an associated clock body. 
According to still another aspect of the present invention, a minute hand 
wheel 92 of the output gear train is displaced from the center of the 
lower casing in order to achieve a compact arrangement. More particularly, 
a center wheel 91 and minute hand wheel 92 are included in the output gear 
train 15 meshing with the output pinion 43 of the rotor 12 and the minute 
hand wheel 92 is so provided as to be operatively connected with the 
manually rotating wheel 58 of the lower casing 13 displaced to the side 
radially opposed to the base 52 from the center of the lower casing 13, as 
seen specifically in FIG. 20. 
As seen in FIG. 3, an annular recess 101 having a curved bottom surface 
extending in the peripheral direction substantially by the same length as 
the coil winding zone of the stator block 11 is formed also in the upper 
casing 14, so that the both recesses 51 and 101 of the both casing 13 and 
14 will oppose each other when the casings are fitted together, for 
enclosing the stator block 11 in these recesses. Four pressing projections 
102 to 105 are provided on the inner surface of the upper casing 14 so as 
to press, from above as seen in FIG. 10, the respective end portions of 
the core 21 into their engagement in respective clearances between the 
arcuate part of the sector base 52 of the lower casing 13 and the pressing 
projections 55 and between the respective radial sides of the base 52 and 
the pressing projections 56 and 57, and pins 106 and 107 to be engaged 
respectively in an axial hole of the rotor 12 and center wheel 92 of the 
output gear train 15 are also provided to project in the casing 14. 
Further, screw inserting holes 108 to 111 aligned respectively with the 
projections 62 and 63 of the lower casing 13 and with the holes 83 and 84 
of the printed base plate 71 are provided in the upper casing 14. Thus, 
the upper and lower casings 13 and 14 and printed base plate 71 can be 
easily and reliably fixed by means of screws 89 and 90 in addition to the 
foregoing screws 85 and 86. Further, a fixed gear 112 having 11 teeth is 
provided on the upper casing 14 at the position of inserting the axial 
shaft 93 of the minute hand wheel 92 in the upper casing 14, that is, at 
the position substantially symmetrical with the pin 106 engaging with the 
rotor 13 with respect to the center of the upper casing 14. In the present 
instance, as will be clear in FIGS. 2 and 19, the fixed gear 112 is formed 
within a recess as retreated from the outer surface of the upper casing 
14, so as to reduce the thickness of the entire movement 10. Further, 
three apertures 113 to 115 for clamping the movement 10 to a later 
described clock body are provided on the periphery of the upper casing 14, 
and these apertures are varied in the shape to have wide and narrow 
portions. 
On the other hand, by references to FIGS. 14 and 15, an associated clock 
body 120 has a circular recess 121 substantially of the same diameter as 
the outer diameter of the movement 10, for incorporating the movement 10 
to the clock body 120. Engaging projections 122 to 124 projecting inward 
in the radial directions are provided on the peripheral wall of the 
circular recess 121 and, when the engaging projections 122 to 124 are 
fitted respectively into the apertures 113 to 115 and the movement 10 is 
rotated, the engaging projections 122 to 124 will engage respectively into 
the narrow portion from the wide portion of the respective apertures 113 
to 115 and the movement 10 can be clampingly mounted to the clock body 
120. In this case, it is preferable that a recess 116 is formed in the 
periphery of the upper casing 14 and a projection 125 engageable into the 
recess 116 is provided in the circular recess 121 of the clock body 120 so 
as to stop a rotation of the movement 10 in the recess 121. 
Referring next to FIGS. 16 and 17, the clock body 120 comprises a cover 
body 131 having a transparent round covering 132 which is fitted to the 
body 120 by means of screws, and a dial in the center of which, for 
example, such two hands as a minute hand 126 and hour hand 127 rotate. 
Particularly with reference to FIGS. 18, 19 and 20, the minute hand 126 is 
fitted to the shaft 93 of the minute hand wheel 92 through a minute hand 
bush 129 having an eccentric cam 129a and tightly receiving the shaft 93. 
The eccentric cam 129a itself is fitted in a center hole 127a in the base 
part of the hour hand 127. An internal gear 127b is formed on the bottom 
surface of the base part of the hour hand 127 is provided with 12 teeth. 
When a driving force is transmitted through the eccentric cam 129a from 
the minute hand wheel 92, the internal gear 127b will mesh with the fixed 
gear 112 formed as retreated from the outer surface of the upper casing 14 
while being eccentric with respect to the minute hand wheel shaft 93. The 
gear ratio is set to be 11:12 and, when the minute hand wheel 92 rotates 
by 360 degrees, the hour hand will rotate by 1/12 rotation, that is, by 30 
degrees. Further, the clock body 120 is provided preferably with a solar 
battery 133 so that a current source voltage will be given from the solar 
battery 133 to the circuit block 16 through a secondary battery (not 
shown) provided preferably in the clock body 120. 
Further, the operation of the present invention shall be described. Now, in 
the particular embodiment shown, a voltage is applied to the circuit block 
16 from the secondary battery charged with the voltage from the solar 
battery 133, and an electric current of such wave-form as in FIG. 13 will 
be made to flow through the coil 25 of the stator block 10 from the 
controlling circuit of the circuit block 16 at intervals of 30 seconds. 
(It will be easily understood that, though two hands are used in this 
embodiment, it should be apparent to the one skilled in the art that three 
hands can be employed and, in such case, the wave-form of FIG. 13 will be 
generated every second and a desired reduction gear train is to be added.) 
Therefore, the respective end portions 22 and 23 of the core 21 will be 
magnetized alternately and, as the distances "a", "b" and "c" between the 
rotor 13 and the respective front and rear sides 23a and 23b of the other 
end portion 23 and the one end portion 22 of the core 21 are a&gt;b&gt;c, the 
rotor 13 will operate at a half rotation step at intervals of 30 seconds 
in the magnetically balanced direction, that is, clockwise in, for 
example, FIGS. 2 and 10. 
With the rotation of the rotor 13, the torque will be transmitted to the 
center wheel 91 and minute hand wheel 92 and, if the reduction ratio of 
the speed of the minute hand wheel 92 to the speed of the output pinion 43 
of the rotor 13 through the center wheel 91 is made 1/60, the minute hand 
wheel 92 will make 1/120 rotation. As the shaft 93 of the minute hand 
wheel 92 projects upward from the center of the fixed gear 112 displaced 
from the center of the upper casing 14 but the movement 10 is attached to 
the clock body 120 so as to have the shaft 93 aligned with the center of 
the dial 128, the time indicating operation will not be obstructed. 
Minutes will be thus indicated by the minute hand 126 coupled to the shaft 
93. 
Further, the internal gear 127b at the base part of the hour hand 127 is 
rotated through the eccentric cam 129a of the minute hand bush 129 fixed 
to the shaft 93 and made integral with the minute hand 126 and, as this 
internal gear 127b meshes with the fixed gear 112 of the upper casing 14, 
the hour hand 127 achieves 1/12 rotation for every rotation of the minute 
hand wheel 92 and hours will be indicated by the hour hand 127. 
On the other hand, the time can be properly adjusted by forcibly rotating 
from outside the lower casing 13 the manually rotating wheel 58 operating 
integrally with the minute hand wheel 126. At this time, the rotor 12 is 
also moved jointly but, when a force larger than the electric rotary 
torque is applied, the rotor 12 can freely rotate within the circular 
recess 53 of the sector base 52 and, therefore, the output gear train 15 
and others will not be overloaded. 
According to the present invention having such arrangements as described 
above, particularly, as the magnetic poles formed of the respective end 
portions of the core 21 of the stator block 11 are arranged as opposed to 
each other in the radial direction of the ring-shaped core 21 and the 
minute hand wheel 92 driven by the center wheel 91 operatively connected 
with the rotor 12 is arranged as displaced from the center of the stator 
block 11, even if the diameter of the coil 25 of the stator block 11 is 
relatively small, the internal components of the movement 10 can be housed 
efficiently the internal space of the coil 25 and well within the outline 
of the coil 25, utilizing the space enlarged by the off-centered minute 
hand wheel 92. Therefore, the internal components of the movement 10 can 
be compactly arranged to be thin and small, so that the upper and lower 
casings 13 and 14 can be made substantially only slightly larger than the 
stator block 11, and the total volume of the movement 10 can be remarkably 
minimized. Further, in the present instance, the hour hand can be actuated 
by the meshing of the fixed gear with the eccentrically rotating internal 
gear and at least one transmitting gear can be omitted as compared with 
conventional movements. In addition, as the fixed gear is positioned as 
retreated from the outer surface of the upper casing, the volume can be 
greatly made smaller in this respect, too. 
Further, as a round-sectioned bar is adopted for the core 21 of the stator 
block, the space factor can be greatly improved and, with the same driving 
torque to be obtained, the diameter of the stator block can be made 
smaller and the entire volume can be also made smaller. 
Further, by adopting the round-sectioned bar material for the core 21, the 
coil 25 as wound on the supporter 24 in advance can be fitted to the core 
21 and, as compared with a flat core which has magnetic poles formed by 
expanding the end portions and on which a coil must be annularly wound, 
the manufacturing work can be greatly simplified. 
As the volume can be made smaller, the general usage of the movement in 
various sized clocks is high and yet the movements can be mass-produced 
very economically.