As electronic articles such as the electronic trading cards (“ETC”) illustrated in U.S. Pat. No. 6,200,216 continue to set the standard for entertaining novelty items or greeting cards, there is an increasing demand to improve the animation quality of devices which do not rely upon the transmission of electronic data to convey a message or present an artistic work in an entertaining way. Animated greeting cards, which rely upon a mechanized actuator, are perhaps the most notable of these latter devices. Constraints in existing actuators used in such cards have been the primary reason they have not yet been able to convey a message, or display a character in a way that comes close to approximating the animation quality of articles such as the ETC.
Existing animation actuators suffer from numerous drawbacks: they are fragile; they consume power inefficiently, and they typically can only be used in one particular device configuration. The animated greeting card described in U.S. Pat. No. 5,139,454 (“'454 Patent”) illustrates these drawbacks.
The card disclosed in the '454 Patent contains an actuator employing a bimetallic wire about 0.003 to 0.010 inches in diameter. This wire is affixed at one end to a circuit board and at the other to a gear. A Flexinol (Dynalloy) shape memory alloy CVAA″) wire is disclosed in the '454 Patent as one example of a useful wire. Upon application of electric current to the wire, the wire contracts thereby exerting a force on the gear which causes the gear to rotate The '454 Patent discloses that a one inch long wire which is 3 millimeters in diameter can be activated by a pulsed current of about 0.75 volts at 6 ohms.
While application of a SMA wire in an actuator such as that disclosed in the '454 Patent has inherent advantages (e.g., as disclosed in detail hereinafter, minimal contraction of a SMA wire can move an attached element a relatively substantial distance), there are numerous drawbacks attendant to the actuator used in the animated greeting card design disclosed in the '454 Patent. It is inherently limited to an open-flap greeting card design and is not readily adaptable to other applications, e.g., a panel display greeting card. It uses small-module size, non-replaceable button batteries. The linear configuration of the SMA wire in the actuator used in the '454 Patent subjects the wire to significant stress, which in turn can either break the wire or limit the movement of the attached moving features. Further, in the actuator illustrated in the '454 Patent, the SMA wire draws a current at a rate that would quickly drain the specified power source. And, in the actuator of the '454 Patent, the wire length is necessarily fairly short, thereby effectively limiting the mechanical force which the wire can convey to the connected gear.
Accordingly, the need exists for versatile animation actuators that are adaptable to numerous animated entertainment devices. Ideally, such actuators will facilitate the efficient use of power, be durable, and be adaptable to numerous configurations. Further, the need exists for animated entertainment devices that employ such actuators to achieve a level of animation approximating that of items such as the ETC.