Touch panel

• US 8,395,588 B2
• Filed: 09/12/2008
• Issued: 03/12/2013
• Est. Priority Date: 09/19/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yamashita, Yuichiro, Johnson, Michiko, Hasegawa, Shin
• Primary Examiner(s): Xiao, Ke
• Application Number:
  US12/210,044
• Publication Number:
  US 20090073142A1
• Time in Patent Office: 1,642 Days
• Field of Search: 345173-176
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A touch panel includes a light guide including a first face for detecting the position of an object in contact therewith and a second face opposite the first face, and a line sensor for receiving light emitted from a side face of the light guide plate, wherein, of light irradiated from the second face side, the light guide guides toward the side face the portion of light reflected by the object.

Claims

1. A touch panel comprising:

a light guide including a first face for detecting a position of an object in contact therewith and a second face opposite the first face; and

a line sensor constructed to receive light emitted from a side face of the light guide,

wherein the light guide guides a portion of light reflected by the object, of light irradiation from the second face side, toward the side face, and

wherein the light guide comprises;

a plurality of first light guide units which have a first refractive index and are arranged at constant intervals; and

a second light guide unit which has a second refractive index lower than the first refractive index and fills gaps between the first light guide units.

2. The touch panel according to claim 1, further comprising:

a first light source constructed to irradiate visible light to be used for display of a display panel in which display elements are arrayed;

a second light source constructed to irradiate invisible light of a wavelength different from the first light source from the second face toward the first face;

another line sensor, arranged on another side face of the light guide, constructed to receive light emitted from the other side face of the light guide; and

visible light cut filters, respectively provided between light-receiving surfaces of the line sensors and the side faces of the light guide, constructed to cut the visible light,

wherein the light guide guides a portion of light reflected by the object, the reflected portion of light comprising light irradiation from the second face, toward at least one of the side faces.

3. The touch panel according to claim 2, wherein the side faces of the light guide include a first side face and a second side face which are not opposite to each other, and the line sensors are arranged on the first and second side faces.

4. The touch panel according to claim 2, wherein each of the first light source and the second light source comprises a plurality of light emitting elements arranged at constant intervals over the entire display panel.

5. The touch panel according to claim 2, wherein the first light source includes at least one first light emitting element which emits the visible light and a light guide for a light source,

the second light source includes at least one second light emitting element which emits the invisible light and the light guide for a light source, and

the light guide for a light source is shared by the first and second light sources, and guides the visible light and invisible light from the first and second light emitting elements over the entire display panel.

6. The touch panel according to claim 2, wherein the invisible light is infrared radiation.

7. The touch panel according to claim 1, further comprising a reflective member provided on a side face of the light guide opposite to a side face on which the line sensor is arranged.

8. The touch panel according to claim 1, further comprising a specification unit constructed to specify a position in the light guide of an object in contact with the light guide based on a position of the line sensor with a peak signal value of signals output from of the line sensor.

9. The touch panel according to claim 1, wherein a portion of the light guide has a curved surface.