The present invention concerns various apparatus and methods for and actuator and display using a shape memory spring. More particularly, the invention defines various apparatus and methods for imparting tactile information to visually impaired persons, especially by a computer controlled haptic display. However, certain applications of the present invention may be outside of this field.
Persons with impaired vision rely upon haptic inputs, those inputs related to the sense of touch, to receive data and appropriate that data into a network of related information. There are several different methods for providing haptic inputs. For example, visually impaired students may be taught stereochemistry through the use of three-dimensional molecular models. Also, braille has traditionally been used for representing words. Printers capable of braille embossing now have the ability to make xe2x80x9cdot artxe2x80x9d or pictures made up of closely-spaced braille dots. Yet another technique includes the use of tactile image paper, which is specially treated so that inked areas on the paper will rise when heated in a special machine.
The solutions thus described suffer from several drawbacks. One drawback is that the haptic information is presented in a more or less permanent form. Presentation of additional haptic information requires fabricating another haptic display, such as another molecular model or another braille-embossed sheet of paper. Another drawback is that fabrication of the additional haptic display could require considerable time. Yet a third drawback of these methods is that fabrication of the additional display may require equipment that is expensive or bulky.
The methods described are not fully compatible with the long distance, rapid communication of large amounts of data made possible by modern electronics. There is a need for haptic devices that are both computer controlled and refreshable. One approach to such a solution uses piezoelectric actuators to raise and lower an array of braille dots. Such apparatus have proven to be bulky, fragile, and costly. There is a need for a two-dimensional refreshable haptic display with reduced size, weight, and cost, and improved reliability.
The present invention provides for an apparatus that includes a first spring made from a shape-memory material. The apparatus includes an electrical power supply for heating the first spring, the electrical power supply being constructed and arranged for passing electrical current through the first spring. The apparatus includes a second spring and a member with a surface, the member defining a hole. The apparatus includes a pin urged in a first direction by the first spring after the first spring is heated. The pin is urged in a second direction by the second spring, the first direction being generally opposite of said second direction. The pin has a first position wherein a portion of the pin passes through the hole and extends beyond the surface. The apparatus includes a supporting mechanism for supporting the pin in the first position.
It is an object of the present invention to provide an improved actuator which is actuated by heating a shape-memory spring.