GB1586056A - Pulse motors - Google Patents

Description

(54) PULSE MOTORS (71) We, RICOH WATCH Cod., a Japanese company, of 28-24, Izumi 2-chome, Higashi-ku, Nagoya-shi, Aichi-ken, Japan do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pulse motors particularly, although not exclusively, for electronic timepieces such as hand-indication wristwatches.

According to the present invention there is provided a pulse motor comprising a rotor having magnet elements whose magnetic axes extend axially of the rotor, the rotor being disposed between an upper stator portion and a lower stator portion, the upper stator portion and the lower stator portion each comprising first and second stator members separated by a gap, the gaps being crossed by the poles of the magnet elements upon rotation of the rotor, the upper and the lower stator portions being separated by a common spacer of nonmagnetic material, the stator members being coupled magnetically to a driving coil for producing opposite alternating magnetic poles on the first and second stator members respectively.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way 6f example only, to the accompanying drawings. in which: Figure 1 is a cross-sectional view of a movement of a handqndication type electronic timepiece, including a pulse motor; Figure 2A is a pictorial view of a known pulse motor; Figure 2B is a plan view of the known pulse motor; Figure 3 is a pictorial view of a rotor for a pulse motor; Figure 4 is a pictorial view of one embodiment of a pulse motor in accordance with the present invention; Figure 5 is a pictorial view of another embodiment of a pulse motor in accordance with the present invention; and Figure 6 is a pictorial view of yet another embodiment of a pulse motor in accordance with the present invention.

Figure 1 shows a movement M to which output pulses are delivered from an electronic control circuit (not shown).

As will be clear from Figure 1, the movement M comprises a pulse motor P and an indicating mechanism I. Output pulses from the control circuit are applied to a driving coil of the pulse motor P, and a rotor 12 of the motor is advanced stepwise by each pulse.

The pulse motor P thus acts as electromechanical transducer. Rotation of the rotor 12 is transmitted to a minute wheel 14 through a rotor pinion 60. A minute hand 18, which is mounted on the end of a minute wheel arbor 62, is moved by each pulse. A minute wheel pinion 64 fixed on the minute wheel 14 engages a third wheel and pinion 66, which has a third wheel pinion 68 meshing with an hour wheel 70. The hour wheel 70 rotates around the minute wheel arbor 62, and the hour hand 16 is mounted on the end of an hour wheel tube 72. Thus rotation of the minute wheel 14 is reduced by 1/60 by the third wheel and pinion 66 before it is transmitted to the hour wheel 70.

A known pulse motor suitable for the above movement M is shown in Figures 2A and 2B. The motor of Figures 2A and 2B has a rotor 101 corresponding to the rotor 12 of Figure 1. The rotor 101 rotates around a shaft 101a, and is constructed as shown in Figure 3, with six permanent magnet elements whose axes are parallel with the axis of the shaft 101a. These magnet elements are distributed around an imaginary cylindrical surface X co-axial with the shaft 101a, and are positioned at angular intervals of 60O with the poles alternating circumferentially. A rotor pinion 101b is mounted on the shaft 101a of the rotor 101 to transmit its rotation.

An upper stator portion comprises a pair of upper stator members 102a and 103a which are in the form of plates and are perpendicular to the shaft 101a. Between the upper stator members 102a and 103a is a gap having two portions al and a2, which are disposed symmetrically one on each side of the shaft 101a so as to lie over magnetic poles of opposite polarity on the upper face of the rotor 101. A lower stator portion comprises a pair of lower stator members 102b and 1 03b which are also in the form of plates and are also perpendicular to the shaft 101a.

Between the lower stator members 102b and 103b is a gap having two portions b1 and b2, which are disposed symmetrically one on each side of the shaft 101á so as to lie under magnetic poles of opposite polarity on the lower face ofthe rotor 101. The upper gap portion al is displaced by an angle of 60 from the lower gap portion b1 , while the upper gap portion a2 is displaced by the same angle of 60 from the lower gap portion b2.

A spacer 104 is sandwiched between the upper and lower stator members 1 02a and 102b, while another spacer 105 is held between the upper and lower stator members 103a and 103b. The spacers 104 and 105 are each composed of several magnetic layers respectively and are used to define a space between the upper and lower stator portions and to couple them magnetically. The spacers 104 and 105 are not one-piece components but are made up of several laminated layers of magnetic material so as to reduce eddy-current loss caused by the driving pulses.

The upper stator member 102a, the spacer 104, and the lower stator member 102b thus combined into a set are joined to one end of a core 106, while the upper stator member 103a, the spacer 105, and the lower stator member 1 03b are joined as a set to the other end of the core 106 and is thereby coupled magnetically to the upper and lower stator members 102a, 102b and 103a, 103b respectively. Consequently the upper stator member 102a, the spacer 104, and the lower stator member 102b are magnetised with one polarity.

The upper stator member 1 03a, the spacer 105, and the lower stator member 103b are magnetised with the other polarity.

Machine screws 108 and 109 connect together the upper and lower stator members with the spacers to form a single assembly; and screws 110, 111 connect the core 106 with the spacers and the lower stator members.

Holes 112 to 115 are for receiving reference pins for positioning the motor. Such reference pins are provided on any device where the pulse motor is fixed, for example in a watch casing.

When the upper gap portions al and a2 of the face different magnetic poles on the upper face of the rotor 101, the lower gap portions bl and b2 face likewise different magnetic poles on the lower face of the rotor 101. As already described, a phase difference of 60 is given between the upper and lower gap portions al, a2 and bl, b2 and as a result, the upper gap portion a1 and the lower gap portion bl both face magnetic poles of one polarity, while the upper and lower gap portions a2 and b2 face magnetic poles of the opposite polarity. Thus, when AC pulses are applied to the driving coil 107, the upper and lower stator members 102a and 102b are magnetised alternately with N or S polarity, while the upper and lower stator members 103a and 103b are magnetised alternately with S or N polarity. At the four gap portions al, a2, bl and b2 magnetic attraction and repulsion will occur between the rotor 101 and these gap portions so as to run the rotor 101 in one direction. In this way the rotor can be driven stepwise by one magnetic pole with each pulse.

Conventional pulse motors of the above construction and operation require separate fixing of the two assemblies each comprising one of the spacers 104 and 105 and the upper and lower stator members 102a, 102b or 103a, 1 03b respectively.

To assemble the motor properly, two holes must be made for positioning each assembly and, in addition, two reference pins must be provided, i.e. as many as the holes, on any device or product where the pulse motor is to be mounted. However, difficulty in design is increased with an increasing number of reference pins, especially in wristwatches and the like where the pulse motor must be fitted in a limited space. The pulse motor shown in Figures 2A and 2B requires four reference pins, which have proved considerably difficult to arrange.

Furthermore, as described above, each spacer is constructed from a plurality of layers of magnetic material. This may result in slight differences in thickness of individual spacers which may cause difficulty in setting pairs of opposite stator members properly in position. Thus, non-adjustment cannot be possible for conventional pulse motors.

Another disadvantage is that the spacers must be made of magnetic material in the known pulse motor, magnetic materials being not easily workable.

Figure 4 shows one embodiment of a pulse motor in accordance with the present invention.

The pulse motor shown in Figure 4 has a spacer 116 common to both upper and lower stator portions instead of the two spacers 104 and 105 of the pulse motor shown in Figures 2A and 2B, and each stator member has an extension e. The spacer 116 is made of nonmagnetic material instead of magnetic material and is a one-piece component, not separated into two parts as are the spacers 104 and 105 in Figures 2A and 2B. The extensions e are portions of the individual stator members which extend to be coupled magnetically directly to the driving coil 107, not through the spacer 116. The upper and lower extensions e hold between them the core 106 at each side respectively, magnetic packing 117 being provided between the core 106 and the lower extensions e. The stator members, the core and the packing are fixed together by screws 110 and 111. The screws 110 and 111 together with screws 108 and 109 serve to mount the pulse motor.

Thus, in the pulse motor shown in Figure 4, the one-piece common spacer 116 and the upper and lower stator members 102a, 102b and 103a, 1 03b holding the spacer therebetween can be assembled to form a single unit. All that is required for locating the unit is two holes 113 and 115. Therefore, the number of reference pins can be reduced, compared with the known pulse motor shown in Figures 2A and 2B.

Furthermore, in the pulse motor of Figure 4, the spacer 116 is formed of non-magnetic material and as one piece. This makes it easy to fabricate the spacer 116 of even thickness, and consequently the gap portions al, a2 and bt, b2 can be properly positioned. The pulse motor thus produced requires no adjustment.

However, it is difficult to remove the driving coil 107 from the pulse motor of Figure 4. This is because the pulse motor shown in Figure 4 has stator member extensions coupled magnetically to the driving coil 107, by fitting the core 106 between the upper and lower extensions e, as already explained.

With this arrangement the screws 108, 109, 110 and 111 must all be removed before the upper stator members 102a and 103a can be removed to allow removal of the driving coil 107. This is inconvenient.

The pulse motor shown in Figure 5 overcomes this drawback by providing a bent extension e on each upper stator member which directly contacts the associated lower stator member. In other words, in the pulse motor of Figure 5, the extensions e of the upper stator members 1 02a and 1 03a are bent like a crank so as to lie on the extensions e of the respective lower stator members 1 02b and 103b. The core 106 is mounted at each end on top of the two superposed extensions e and is then fixed in position with the screws 110 and 111.

In the pulse motor of Figure 5, the driving coil 107 can be taken off just by removing the screws 110 and 111 without removing the upper stator members 1 02a and 103a. Removal of the driving coil 107 is thus made considerably easier than in the pulse motor of Figure 4. In this manner a pulse motor can be produced which is easy to mount, has an easily removable driving coil, and in which adjustment is unnecessary.

In the embodiment of Figure 5, the extensions e of the upper stator members 1 02a and 103a are bent like a crank and overlaid on the lower stator members 102b and 103b, and the core 106 is mounted thereon. In an alternative construction (not illustrated), the extensions e of the upper stator members 102a and 103a may be arranged to engage side faces of the core 106 without being superposed on the lower stator members 102b and 103b. In this construction, the driving coil 107 may also be removed easily.

Pulse motors which are used in wristwatches have stator members which are about 0.2mm thick. These stator members are fixed one on each side of the spacers with screws. When the screws are tightened, the stator members are warped away from the spacer, particularly at the edge forming the gap portions of the stator members which is some distance from the screws. This necessitates fine adjustment of these stator members.

This disadvantage can be eliminated by fastening the stator members uniformly with several screws, but from the design viewpoint it is rather inconvenient to add even one more screw to any device having such a high density of components as a wristwatch.

The pulse motor shown in Figure 6 overcomes this difficulty by constructing the spacer as a two-piece component, although the spacer as a whole is still common to both sets of stator members. One part of the spacer is fixed to the upper stator members and the other to the lower stator members.

The pulse motor shown in Figure 6 thus has upper and lower spacer parts 118 and 119 which meet at a joint plane which is perpendicular to the axis of the rotor 101.

The upper stator members 1 02a and 1 03a are fixed to the upper face of the upper spacer part 118, and the lower stator members 102b and 103b to the lower face of the lower spacer part 119. This is done, for example, by spot welding or by bonding with adhesive.

The pulse motor of Figure 6 is assembled by first putting the lower spacer part 119 having the lower stator members 102b and 1 03b attached thereto in position, then setting the rotor 101 in a central opening 11 9a in the spacer part 119, mounting the upper part 118, having the upper stator members 102a and 103a fixed thereto, on the lower spacer part 119, and finally fixing them with the screws 108 and 109 as in the pulse motor of Figure 5.

The pulse motor shown in Figure 6 has relatively thick spacer parts to which the thin stator members are fixed. This prevents the thin stator members from being warped when the screws 108 and 109 are tightened.

Pulse motors in accordance with Figures 4 to 6 require no means for fine adjustment owing to the ease of initial setting of the gap portions of the individual stator members.

Also the pulse motors are highly shock-proof, the spacers serving as reinforcing plates. Also, it has the advantage of easy mounting.

WHAT WE CLAIM IS: 1. A pulse motor comprising a rotor having magnet elements whose magnetic axes extend axially of the rotor, the rotor being disposed between an upper stator portion and a lower stator portion, the upper stator portion and the lower stator portion each comprising

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   110 and 111. The screws 110 and 111 together with screws 108 and 109 serve to mount the pulse motor.

   Thus, in the pulse motor shown in Figure 4, the one-piece common spacer 116 and the upper and lower stator members 102a, 102b and 103a, 1 03b holding the spacer therebetween can be assembled to form a single unit. All that is required for locating the unit is two holes 113 and 115. Therefore, the number of reference pins can be reduced, compared with the known pulse motor shown in Figures 2A and 2B.

   Furthermore, in the pulse motor of Figure 4, the spacer 116 is formed of non-magnetic material and as one piece. This makes it easy to fabricate the spacer 116 of even thickness, and consequently the gap portions al, a2 and bt, b2 can be properly positioned. The pulse motor thus produced requires no adjustment.

   However, it is difficult to remove the driving coil 107 from the pulse motor of Figure 4. This is because the pulse motor shown in Figure 4 has stator member extensions coupled magnetically to the driving coil 107, by fitting the core 106 between the upper and lower extensions e, as already explained.

   With this arrangement the screws 108, 109, 110 and 111 must all be removed before the upper stator members 102a and 103a can be removed to allow removal of the driving coil 107. This is inconvenient.

   The pulse motor shown in Figure 5 overcomes this drawback by providing a bent extension e on each upper stator member which directly contacts the associated lower stator member. In other words, in the pulse motor of Figure 5, the extensions e of the upper stator members 1 02a and 1 03a are bent like a crank so as to lie on the extensions e of the respective lower stator members 1 02b and 103b. The core 106 is mounted at each end on top of the two superposed extensions e and is then fixed in position with the screws 110 and 111.

   In the pulse motor of Figure 5, the driving coil 107 can be taken off just by removing the screws 110 and 111 without removing the upper stator members 1 02a and 103a. Removal of the driving coil 107 is thus made considerably easier than in the pulse motor of Figure 4. In this manner a pulse motor can be produced which is easy to mount, has an easily removable driving coil, and in which adjustment is unnecessary.

   In the embodiment of Figure 5, the extensions e of the upper stator members 1 02a and 103a are bent like a crank and overlaid on the lower stator members 102b and 103b, and the core 106 is mounted thereon. In an alternative construction (not illustrated), the extensions e of the upper stator members 102a and 103a may be arranged to engage side faces of the core 106 without being superposed on the lower stator members 102b and 103b. In this construction, the driving coil 107 may also be removed easily.

   Pulse motors which are used in wristwatches have stator members which are about 0.2mm thick. These stator members are fixed one on each side of the spacers with screws. When the screws are tightened, the stator members are warped away from the spacer, particularly at the edge forming the gap portions of the stator members which is some distance from the screws. This necessitates fine adjustment of these stator members.

   This disadvantage can be eliminated by fastening the stator members uniformly with several screws, but from the design viewpoint it is rather inconvenient to add even one more screw to any device having such a high density of components as a wristwatch.

   The pulse motor shown in Figure 6 overcomes this difficulty by constructing the spacer as a two-piece component, although the spacer as a whole is still common to both sets of stator members. One part of the spacer is fixed to the upper stator members and the other to the lower stator members.

   The pulse motor shown in Figure 6 thus has upper and lower spacer parts 118 and 119 which meet at a joint plane which is perpendicular to the axis of the rotor 101.

   The upper stator members 1 02a and 1 03a are fixed to the upper face of the upper spacer part 118, and the lower stator members 102b and 103b to the lower face of the lower spacer part 119. This is done, for example, by spot welding or by bonding with adhesive.

   The pulse motor of Figure 6 is assembled by first putting the lower spacer part 119 having the lower stator members 102b and 1 03b attached thereto in position, then setting the rotor 101 in a central opening 11 9a in the spacer part 119, mounting the upper part 118, having the upper stator members 102a and 103a fixed thereto, on the lower spacer part 119, and finally fixing them with the screws 108 and 109 as in the pulse motor of Figure 5.

   The pulse motor shown in Figure 6 has relatively thick spacer parts to which the thin stator members are fixed. This prevents the thin stator members from being warped when the screws 108 and 109 are tightened.

   Pulse motors in accordance with Figures 4 to 6 require no means for fine adjustment owing to the ease of initial setting of the gap portions of the individual stator members.

   Also the pulse motors are highly shock-proof, the spacers serving as reinforcing plates. Also, it has the advantage of easy mounting.

   WHAT WE CLAIM IS: 1. A pulse motor comprising a rotor having magnet elements whose magnetic axes extend axially of the rotor, the rotor being disposed between an upper stator portion and a lower stator portion, the upper stator portion and the lower stator portion each comprising

   first and second stator members separated by a gap, the gaps being crossed by the poles of the magnet elements upon rotation of the rotor, the upper and the lower stator portions being separated by a common spacer of nonmagnetic material, the stator members being coupled magnetically to a driving coil for producing opposite alternating magnetic poles on the first and second stator members respectively.
2. 2. A pulse motor as claimed in Claim 1, in which the spacer is a one-piece component.
3. 3. A pulse motor as claimed in Claim I, in which the spacer is a two-piece component the two parts of which meet at a joint plane which is perpendicular to the axis of the rotor.
4. 4. A pulse motor as claimed in Claim 3, in which one piece of the spacer is fixed to the upper stator portion and the other piece is fixed to the lower stator portion.
5. 5. A pulse motor as claimed in any one of the preceding claims, in which each stator member has an extension coupled with the driving coil.
6. 6. A pulse motor as claimed in Claim 5, in which each extension is co-planar with the remainder of the respective stator member.
7. 7. A pulse member as claimed in Claim 5, in which the extensions of the sector members of one of the stator portions are bent into contact with the extensions of the stator members of the other stator portion.
8. 8. A pulse motor as claimed in any one of the preceding claims, in which the rotor has six magnet elements which are angularly equally spaced about the axis of the rotor.
9. 9. A pulse motor as claimed in any one of the preceding claims, in which the gaps between the respective stator members are elongate and are angularly offset from one another about the axis of the rotor.
10. 10. A pulse motor substantially as described herein with reference to Figure 3 and to any one of Figures 4 to 6 of the accompanying drawings.
11. 11. A timepiece including a pulse motor in accordance with any one of the preceding claims.