Electrostatic alpha-numeric display

A display device comprising

• an array of controllable bistable rotatable electret elements with contrasting colors on opposite sides to effect a change in appearance upon change of position so that a desired visible pattern is produced by selective positioning of the elements,
• each electret element having a pivot axis about which it can rotate to either of two stable positions and two opposed edge portions spaced from the pivot axis and bearing opposite electrical charges,
• a frame member comprising an insulating panel having an array of windows each provided with pivot points for rotatably supporting an electret element,
• pairs of conductive strips on the panel at opposite sides of the windows each strip disposed adjacent a charged edge portion of an electret element, whereby when voltage is applied across each pair of strips electrostatic forces are developed on the charged edges to selectively effect rotation of the electret elements, and
• means including conductive paths on the panel connected to the strips for supplying control voltages to the strips to effect a visible display pattern by selective positioning of electret elements.

A display device with a nonvolatile memory function comprising

• an array of controllable bistable movable electret elements which change in appearance upon change of position so that a desired visible pattern is produced by selective positioning of the elements,
• each electret element having a pivot axis about which it can rotate to either of two stable positions and two opposed edge portions spaced from the pivot axis and bearing opposite electrical charges,
• a frame member having an array of windows each provided with pivot points for rotatably supporting an electret element,
• pairs of conductive strips on opposite sides of the windows each strip disposed adjacent a charged edge portion of an electret element, whereby when voltage is applied across each pair of strips electrostatic forces are developed on the charged edges to selectively rotate or hold still the electret elements,
• means including a control circuit for supplying control voltages to the strips to effect a visible display pattern by selective positioning of electret elements, and
• means electrically connected with the said circuit for sensing the position of each electret element and electrically providing position information to the circuit whereby the display serves as a nonvolatile memory.

A display device with a nonvolatile memory function comprising

• an array of controllable bistable movable electret elements which change in appearance upon change of position so that a desired visible pattern is produced by selective positioning of the elements,
• each electret element having a pivot axis about which it can rotate to either of two stable positions and two opposed edge portions spaced from the pivot axis and bearing opposite electrical charges, the electret element including a conductive contact element carried by and movable with the electret element,
• a frame member of insulating material having an array of windows each provided with pivot points for rotatably supporting an electret element,
• pairs of conductive strips on opposite sides of the windows each strip disposed adjacent a charged edge portion of an electret element, whereby when voltage is applied across each pair of strips electrostatic forces are developed on the charged edges to selectively rotate or hold still the electret elements,
• means including a control circuit for supplying control voltages to the strips to effect a visible display pattern by selective positioning of electret elements, and
• switch means including pairs of stationary contacts on the frame member electrically connected with the said circuit for selective closing engagement by the contact elements according to the position of each electret element for thereby sensing the position of each electret element and electrically providing position information to the circuit whereby the display serves as a nonvolatile memory.