Motor driving apparatus for perfoming high-speed rotation by pha

Details Motor driving apparatus for perfoming high-speed rotation by pha Motor driving apparatus for perfoming high-speed rotation by pha

1996-08-06

2000-07-18

Wysocki, Jonathan

Electricity: motive power systems

Positional servo systems

With particular motor control system responsive to the...

318254, G05B 1940

Patent

active

060912219

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a motor driving apparatus for performing high-speed rotation by phase detection control.
2. Description of the Prior Art
To rotate a motor at a higher speed is one of the most important factors in terms of an improvement in basic performance of the motor, and has been studied and developed for many years. For example, electrical timepieces, which are one kind of products using motors, have recently been provided with multi-functions, and timepieces having various functions such as stop watch functions, alarm functions, and dual-time functions in addition to normal time display functions have been developed and put into practice. In each of these multi-functional timepieces, when the system is initialized in an initial state, e.g. in loading a battery therein, or when the mode is shifted, or the positions of hands are returned to 0 in normal use, the hands must always be fast-forwarded.
A conventional motor driving apparatus will be described below by exemplifying a stepping motor of an electronic timepiece. FIG. 8 is a view showing the arrangement of a motor driving apparatus constituted by a conventional bipolar stepping motor. FIGS. 9 to 14 are plan views each showing the positional relationship between the magnetic poles of a stator and a rotor. As shown in FIG. 8, the bipolar stepping motor serving as a means for converting an electrical signal into a mechanical rotation motion comprises a driving coil 101, a flat stator 102, and a rotor 103. The flat stator 102 has a step 102a. Motor drivers 104a and 104b are arranged to change the potential across the driving coil 101 and flow a current through the driving coil 101, thereby exciting the flat stator 102. In the case of the bipolar motor shown in FIG. 8, when no current flows through the driving coil 101, the pole position of the rotor 103 with respect to the flat stator 102 is a statically stable point 110 shown in FIG. 9. When a current flows through the driving coil 101 to excite the flat stator 102, the pole position of the rotor 103 with respect to the flat stator 102 is an electromagnetically stable point 111 shown in FIG. 10.
Normally in the electronic timepiece, a pulse signal for changing the potential across the driving coil 101 is output from the motor driver 104a or 104b for 4 to 5 mS to flow a pulse current through the driving coil 101, thereby rotating the rotor 103. The rotor 103 rotates during supply of the current to the driving coil 101. When the magnetic pole of the rotor 103 reaches a position shown in FIG. 11 with respect to the flat stator 102, the current flow through the driving coil 101 is stopped, but the rotor 103 inertially rotates to a position in FIG. 12. Then, the rotor 103 damped-oscillates about the statically stable point 110 and finally stops.
When a pulse signal is output from the motor driver 104a after the rotor 103 becomes stationary, to flow a current through the driving coil 101, thereby exciting the flat stator 102 as shown in FIG. 13, the rotor 103 rotates through 180.degree. in a rotational direction A in FIG. 13. When a pulse signal is output from the motor driver 104b opposite to the motor driver which has previously output the pulse signal after the rotor 103 becomes stationary, the rotor 103 further rotates through 180.degree. in the direction A in FIG. 13. The rotor 103 certainly rotates in the direction A in FIG. 13 by flowing a current through the driving coil 101 after the rotor 103 becomes stationary.
When the stepping motor is to be rotated at a high speed, the rotor 103 must be rotated at a high speed, as a matter of course. At this time, an output interval between pulses output from the motor drivers 104a and 104b must be shortened.
If the output interval between pulse signals is shortened so as to rotate the rotor 103 at a higher speed, a next pulse signal must be output even though the damped oscillation of the rotor 103 immediately after rotation has not stopped yet.
If the next pulse signal is output in a s

REFERENCES:
patent: 3716771 (1973-02-01), Maynard
patent: 3781620 (1973-12-01), Toth
patent: 5451832 (1995-09-01), Cameron et al.
patent: 5483156 (1996-01-01), Nishihara
patent: 5608320 (1997-03-01), Dinsmore et al.

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