Frontlit illuminated touch panel

• US 7,253,809 B2
• Filed: 03/12/2004
• Issued: 08/07/2007
• Est. Priority Date: 04/06/2001
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Boyd, Gary T., Pankratz, Stephan J.
• Primary Examiner(s): Nguyen; Kevin M.
• Application Number:
  US10/799,998
• Publication Number:
  US 20060132453A1
• Time in Patent Office: 1,243 Days
• Field of Search: 345173-183, 362/619, 362/603, 362/559, 362/31, 385/49, 385/146, 385/25, 349/122, 349/63, 349/62
• US Class Current: 345/176
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A frontlit touch panel for use with a reflective light valve, comprising a front light guide having at least one light input face that supplies light to the guide, a viewing face, a light output face opposite the viewing face, and at least one component of a touch-sensitive transducer, the light output face having a light extraction layer thereon having a substantially flat light exit face and containing buried reflective facets that extract supplied light from the guide through the light exit face. The touch panel can be used with a light source, reflective light valve and suitable control electronics to form a compact, efficient illuminated touch panel display assembly.

Claims

1. A flexible film having a substantially flat lower surface which provides a light exit face, a non-planar upper surface having finely-shaped projections with a generally trapezoidal cross-section comprising riser, plateau and facet portions flanked by land portions, and a layer of optically transparent adhesive on the plateau portions, such that if the plateaus are adhesively laminated to a light output face of a substantially planar light guide having at least one light input face that supplies light to the guide, a viewing face and the light output face opposite the viewing face, the resulting assembly encloses pockets containing a medium having a lower refractive index than a material from which the film is manufactured and buried facets which reflect and thereby extract supplied light from the guide through the light exit face.

2. A film according to claim 1, wherein the pockets are not filled with adhesive.

3. A film according to claim 1, farther comprising a carrier film atop the layer of optically transparent adhesive and a second layer of optically transparent adhesive atop the carrier film.

4. A film according to claim 1, wherein the ratio of total plateau length to total land length is greater than 1:

1.

5. A film according to claim 4, wherein the ratio is greater than 3:

1.

6. A film according to claim 1, wherein the facets have varied dimensions, pitch or angular orientation such that when the plateaus are laminated to the light output face of the light guide, the supplied light is evenly distributed across the viewing face.

7. A film according to claim 6, wherein the projections have varied dimensions.

8. A film according to claim 6, wherein the projections have varied pitch.

9. A film according to claim 6, wherein the projections have varied angular orientation.

10. A film according to claim 1, wherein the film comprises polycarbonate, polyacrylate or polystyrene.

11. A film according to claim 1, wherein supplied light that is reflected from the exit face and refracted through a face is recaptured by being refracted through a nearby facet.