Liquid crystal display touch screen having electronics on one side

• US 4,990,901 A
• Filed: 12/13/1988
• Issued: 02/05/1991
• Est. Priority Date: 08/25/1987
• Status: Expired due to Fees

• Current Assignee: Technomarket Opportunity Fund, L.P.
• Original Assignee: Technomarket LP
• Inventors: Beiswenger, John L.
• Primary Examiner(s): Brier, Jeffery A.
• Application Number:
  US07/283,627
• Time in Patent Office: 784 Days
• Field of Search: 340/706, 340/707, 340/712, 340/784, 340/765, 341/31, 250/221, 350/330, 350/331 R, 350/332, 350/345
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0238 Programmable keyboards key guide holders G06F3/0224
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

An apparatus for providing a control signal utilizes a liquid crystal panel and means for transiently forming transparent windows therein. There is a source of electromagnetic radiation (EMR) adjacent the panel and positioned to pass EMR through transiently open windows. There is an EMR detector positioned adjacent the source and a defined EMR path between the source and detector which path is formed in response to a transiently open window and includes an area for the positioning of an object to occlude the EMR radiation passing between the source and detector. The path also includes a reflector which directs EMR from the source back in the same general direction to the detector. There is a timing and logic circuit correlating the opening of the transient windows and the detection of EMR at said detector to provide a control signal.

Claims

1. An apparatus for providing a control signal including a liquid crystal panel and means for transiently forming transparent windows therein, a source of electromagnetic radiation (EMR) adjacent said panel and positioned to pass EMR through transiently open windows, an EMR detector positioned adjacent said source, a defined EMR path between said source and detector, which path is formed in response to a transiently open window, said path including an area for positioning an object to occlude said EMR, and also including reflective means which directs EMR from said source back in the same general direction to said detector, and timing and logic means correlating the opening of said transient windows and the detection of EMR at said detector to provide a control signal.

2. The apparatus of claim 1 further characterized in that said apparatus includes a housing for said panel, source and detector, with said source and detector being adjacent one side of said panel and said reflective means being adjacent an opposite side of said panel.

3. The apparatus of claim 2 further characterized in that said EMR path is in part outside of said housing.

4. The apparatus of claim 3 further characterized in that said EMR path is, in part, outside of said housing between said source and said reflective means and is, in part, outside of said housing between said reflective means and said detector.

5. The apparatus of claim 2 further characterized in that said EMR is visible light.

6. The apparatus of claim 5 further characterized in that said light path includes a mirror which reflects only a portion of said light, with the non-reflected portion passing through the mirror and being visible outside of said housing.

7. The apparatus of claim 6 further characterized by and including a light filter positioned to filter the non-reflected portion of the light which passes through said mirror, with said filter passing light of a particular color.

8. The apparatus of claim 7 further characterized by and including a second filter passing light of a color different from that of said first light filter, said second filter preventing that portion of ambient light which passes said first filter from reaching said detector.

9. The apparatus of claim 1 further characterized in that said reflective means is a retroreflector.

10. The apparatus of claim 1 further characterized in that said transiently formed windows are positioned directly in front of said EMR source.

11. The apparatus of claim 1 further characterized by and including means for preventing ambient light from reaching said detector.

12. An apparatus for providing a control signal including a housing, a liquid crystal panel in said housing and means for transiently forming transparent windows therein, a light source in said housing, along one side of said panel and positioned adjacent said windows, a light detector adjacent and shielded from said light source, a light path between said source and detector, said path including a retroreflector along the side of said panel opposite said source, said path, in part, being outside of said housing to provide for the occlusion of light in said light path, and timing and logic means correlating the opening of said transient windows and detection of light at said detector to provide a control signal.

13. The apparatus of claim 12 further characterized by and including a recessed display area, substantially coextensive with said panel, said light path passing through said recessed display area to permit a light path occluding object to be positioned therein.

14. The apparatus of claim 13 further characterized in that said light source and light detector are positioned along the same side of said panel.

15. The apparatus of claim 13 further characterized bY and including reflector means positioned to deflect a portion of the light from said source into the recessed display area and toward said retroreflector, that portion of the light from said source which is not reflected by said reflecting means passing through said housing.

16. The apparatus of claim 15 further characterized in that light from said retroreflector passes through said reflecting means to reach said detector.

17. The apparatus of claim 16 further characterized by and including means for preventing ambient light from passing through said housing into said detector.

18. The apparatus of claim 17 further characterized in that said means for preventing ambient light from reaching said detector includes spaced light filters, each passing light of a different color.