Horology: time measuring systems or devices – Oscillating or reciprocating means – Pendulum type
Reexamination Certificate
1998-09-21
2001-06-26
Roskoski, Bernard (Department: 2859)
Horology: time measuring systems or devices
Oscillating or reciprocating means
Pendulum type
C368S134000, C368S327000
Reexamination Certificate
active
06250798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to toys, displays, or music boxes that are activated by light and ago are driven by an electric motor powered by solar panels and/or small batteries.
2. Prior Art
It is a very pleasant experience to watch sunlit, colored, and/or rainbow beams of light projected on the walls of a room when sunlight is refracted and reflected by cut crystals. For a greater effect, we have tried to slowly move crystals when they are exposed to sunlight so that the light beams also move throughout the room and the crystals sparkle. The desired motion is a slow oscillation that rotates the crystals between a clockwise and counter-clockwise (or vice versa) motion. We have tried Christmas ornament motors driven by 60 Hz AC power where the power was reduced to low voltage by a transformer or a voltage divider. We have obtained low voltage DC motors that are highly geared down (found in motor driven dolls) and operated them with solar panels or batteries. We have tried various clockworks which use crystal oscillators for timing circuits. We have tried flexible metal motor shafts to transport the rotation from the relatively large motor gear assembly to the crystal. Finally we have tried bi-metalic devices which move when heated by the sun. These ideas have driven the cost above what we think the market will bear, and they are larger than necessary in our judgement.
In order to reduce cost and size of the device, we have come up with the present design which uses none of the above methods. Also we have achieved the more desirable slow, smooth oscillating rotations that are much more interesting than a steady state rotation because the beams of light stop periodically for a clear vision of the beam patterns. In our invention, we are pulse rotating a motor to minimize the size of the motor, power supply and we are using these pulses to excite the natural frequency of a rotational pendulum (a crystal suspended by a thread) such that the crystal rotates in a smooth oscillating manner. The motor, power supply is energized by a small solar panel or a small, light-activated battery.
To drive the motor, we are using a method common to electrical engineers to produce high current pulses from low DC current supplies. An example of this method is found in the automobile where a capacitor is charged by a low current and then discharged at high current through the primary windings of a transformer coil so that sufficient voltage is generated on the secondary winding to create an arc across the gap of a spark plug.
With a variable charging current (especially from the solar panel), a timing circuit used to trigger the discharge of the capacitor such as those found in U.S. Pat. No. 5,760,572 of Takeda and Fujii would, for the most part, discharge the capacitor either too early or too late. When too early, before the capacitor is charged, there is not enough energy to rotate the motor, or when too late, long after the capacitor is charged, the charging time for the next pulse is lost. The chance of a timed discharge to occur exactly at the time the capacitor just charges is very low. By always discharging the capacitor just as the capacitor is charged, as we do, we maximize the efficiency of rotation and hence minimize the size of the solar panel or battery.
It should be noted that we are not trying to move an object from point A to point B or to store energy for use hours later such as found in U.S. Pat. No. 5,760,572 of Takeda and Fujii and U.S. Pat. No. 4,901,295 of Daho Taguezout and Xuan respectively. We are simply maintaining, more or less, the continuous rotation of a crystal. The motion of the crystal, of course, depends on the motor pulse rate (depending on the solar intensity or the age of the battery) and the natural frequency of the rotational pendulum which depends on the thread length and stiffness, and the moment of inertia of the crystal which is suspended by the thread. We are not using geared down motors to turn crystals slowly and continuously such as found in U.S. Pat. No. 5,232,105 of Gregg.
SUMMARY OF THE INVENTION
One objective of this invention is to use a means, such as a crystal, to breakup some of the sunlight that is coming through a window into moving light beams that are projected onto the non-sunlit surfaces of a room for a beautiful light display that is very pleasing to to the observer. Another objective is to slowly move the crystal-like means in an oscillating manner so that the light beams periodically stop so that the beam pattern can be clearly observed. Finally we would like to minimize the cost and size of the solar crystal motion device. We are accomplishing all of these objectives by rotating crystals, which are mounted in a window, in a unique way. In its simplest form, a crystal-set (for example one or more crystals like those used in crystal chandeliers) is suspended from a point by a thread-like member (a silk thread for example) and is rotated around the vertical axis of the thread-like member by means of a motor when sunlight strikes the crystal-set and a solar panel (or a solar switch in the case of a battery). The motor rotates the crystal-set by occasionally pulse rotating the top of the thread-like member near its support point which in turn rotates the crystals. We will define in more detail what we mean by crystal-set, crystal, and thread-like member in the detailed description section.
We are pulse rotating the motor shaft by using the method well known to the electrical engineer of slowly charging a capacitor with a relatively low current DC supply (by means of a battery or a solar panel) and discharging the charged capacitor through the motor windings in a relatively short time to obtain much higher currents; that is, a pulse of relatively high current through the motor windings sufficient to rotate the motor about one rotation. The cycle is then repeated as fast as it takes for the capacitor to recharge. If we were to run the motor continuously, we would need a bulky gear set to reduce the shaft speed and a much larger solar panel or battery to supply the necessary DC current. The size and cost of such a device would be substantially greater and we would not have the desired oscillating effect.
While the thread-like member at its top end is pulsed rotated (about one quick turn every half minute on average) around it's vertical axis, the crystal-set at the bottom end moves smoothly in an oscillating manner between clockwise and counter-clockwise (or vice versa) motion due to the loose coupling through the thread-like member. We could, of course, electronically switch the motor winding leads to reverse the motor shaft rotation after every one or more current pulses, but it would require more circuitry. The crystal-set oscillates very nicely without this complication if attention is given to the mechanical properties of the rotational pendulum (the crystal-set suspended by the thread-like member).
The crystal-set initially rotates in the same direction as the top end of the thread-like member, but by the time of the next rotational pulse, the crystal-set has reversed its direction (or at least stopped) due to the relaxation of the twist in the thread-like member and the moment of inertia of the crystal-set. When the solar intensity is low or as the battery ages, the capacitor takes longer to charge and the pulse rate is reduced. Even so, the crystal motion is still effective.
In the case where a battery is the primary current source there is a photo switch that turns on with exposure to sunlight and allows a low current (limited by a resistor) to flow from the battery into the same circuit used for the case of the solar panel discussed above. Of course, the battery could be used with a solar panel array to help reduce the current drain of the battery and increase the lifetime of the battery.
REFERENCES:
patent: 12196 (1855-01-01), Crane
patent: 2292139 (1942-08-01), Ioew
patent: 2625787 (1953-01-01), Reiner
patent: 4421421 (1983-12-01), Bradt
patent: 5232105 (1993-08-01), Gregg
patent:
Brainard Hertha Ann
Brainard John Paul
Brainard Nicolas Charles
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