Horology: time measuring systems or devices – Electrical time base – Solid state oscillating circuit type
Reexamination Certificate
1999-06-23
2002-11-05
Roskoski, Bernard (Department: 2841)
Horology: time measuring systems or devices
Electrical time base
Solid state oscillating circuit type
Reexamination Certificate
active
06477116
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rotation controller and a rotation control method. More particularly, the invention relates to a rotation controller and a rotation control method for adjusting the speed of a rotary member upon rotating any of various rotary members by the use of a spiral spring, an engine, electric power or human power.
BACK GROUND ART
Japanese Examined Patent Publication No. 07-119812 discloses one of the known electronically controlled mechanical watches based on a process comprising converting mechanical energy produced upon release of a spiral spring into electric energy by means of a generator, causing rotation control means to operate with this electric energy, and controlling the value of current flowing through a coil of the generator, thereby accurately driving a needle fixed to a train wheel and thus accurately displaying the time.
In the disclosed electronically controlled mechanical watch, the rotational speed of the generator is controlled by entering a signal based on the rotation of a rotor of the generator into a counter, entering on the other hand a signal from a crystal oscillator as well into the counter, comparing values from the individual counters, and controlling the generator on the basis of the resulting difference between these values. The counter is one known as an integral counter which compares the phase difference between reference clock pulse (Ref-pulse) and generator rotation period pulse (G-pulse), down-counting the U/D counter when G-pulse is gain, and up-counting the same if G-pulse is in loss.
At the time when a value obtained by measuring the time of one period of Ref-pulse agrees with a value obtained by the integral counter, the generator is braked, and braking is continued until the completion of time measurement of one period of Ref-pulse. The value of the integral counter would therefore sets the brake releasing time. More specifically, the value of the integral counter comprises an integrated value of the brake releasing time at which the average speed of G-pulse agrees with the target speed (Ref-pulse). That is, this system adopts integral control.
However, because the integral control method as described above is based on comparison of signals output during a period while counting them with the counter, it is possible to adjust the average speed of the rotor to a set time for a sufficiently long period of time, thus ensuring substantially constant speed control of operations. The rotation speed of the rotor cannot however be adjusted immediately, leading to a low response. In addition, this method has another problem in that a slight phase difference is produced before alignment with a target frequency be cause of the relationship between the force of the spiral spring and the braking force.
More specifically, integral control can be expressed by a block diagram shown in FIG.
26
. In general, the transfer function used in a generator or a motor is known to be 1/s (sT+1). As shown in
FIG. 26
, this is composed of a primary delay transfer function
601
of 1/(sT+1) and an integral term
602
of 1/s. An integrating factor is therefore included in the generator itself to be controlled. Bode diagrams for a case where only integral control is applied to an object of control are shown in
FIGS. 27 and 28
.
In these Bode diagrams, conditions required for stabilizing rotation control are that the phase upon a phase margin, i.e., 0 db (gain crossing point) is ahead of −180°, and that the gain upon gain margin, i.e., with a phase of −180° (phase crossing point) is up to 0 db.
For integral control alone, however, there occurs a delay of −90° for the object to be controlled, and an additional delay of −90° as a result of integral control, as shown in FIG.
27
. The phase characteristic is therefore that near −180°. It is consequently difficult to ensure stable control because a phase margin or a gain margin is unavailable from the integral control alone. In the watch disclosed in Japanese Examined Patent Publication No. 07-119812, therefore, it is necessary perform control with a very low frequency, and the resultant response is 0.016 Hz or under.
A case where the gain of the integral counter is assumed to be increased to 100 times as large is illustrated in FIG.
28
. In this case also, the phase margin is later than −180°, so that a stable control cannot be expected.
As is clear from the information described above, the conventional control through integral control alone permits average speed adjustment, but involves a problem in that the phase deviation cannot be solved.
Another problem is that it is almost impossible to cope with a sudden disturbance encountered upon production of acceleration in a wristwatch by shaking the arm, because of the slow response of control.
Further, in the above-mentioned watch, using a spiral spring as power, the rotational force largely varies with the extent of winding. This causes a control error which in turn results in a loss or a gain of the watch. When using the watch as a wristwatch, movement of the arm causes an acceleration of the rotor, leading to a disturbance which causes an instable control status, resulting in a change in movement of the needle or a gain or a loss.
Since such an integral control is popularly utilized for controlling a rotary member, these problems are similarly encountered when controlling various rotary member requiring speed adjustment control, not limited to a watch, but including, for example, various toys comprising a rotary member such as a doll rotating under the action of a spiral spring, the drum of a music box, and an electric motor of a hybrid car based on a combination of a gasoline engine and an electric motor.
A first object of the present invention is to provide a rotation controller and a rotation control method which can solve a phase deviation of a rotary member, give a fast response of a control system, and are highly resistance to disturbance.
A second object of the invention is to provide a rotation controller and a rotation control method which permit downsizing of circuit scale and simplification of circuit configuration so as to be applicable to a small device such as a wristwatch.
Disclosure of Invention
The rotation controller of the present invention controlling the rotation period of a rotary member by applying a brake on the rotating rotary member by power supplied from a power source, comprising: rotation detecting means generating a rotation signal corresponding to revolutions of a rotary member; target signal generating means generating a target signal corresponding to target revolutions of the rotary member; phase difference compensating means detecting a phase difference between a rotation signal output by the rotation detecting means and a target signal output by the target signal generating means, and generating a phase difference compensating signal serving as a brake control signal; frequency difference compensating means detecting a frequency difference between the rotation signal and the target signal, and generating a frequency difference compensating signal serving as a brake control signal; and brake control means controlling the manner of braking by means of at least any one of the phase difference compensating signal from the phase difference compensating means and the frequency difference compensating signal from the frequency difference compensating means.
In the present invention, phases are compared between the rotation signal of the rotary member and the target signal of that rotary member, and a phase difference compensating signal serving as a brake control signal is entered into the braking circuit of the rotary member on the basis of the resultant phase difference, thus permitting achievement of a manner of control known as the phase synchronizing circuit control, i.e., PLL (phase-locked loop) control. It is therefore possible to set a braking level by comparing rotation signal waveforms between individual periods of the rotary member. A stable
Ikegami Tomio
Koike Kunio
Shinkawa Osamu
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