Optical waveguide for touch panel, touch panel using the optical waveguide and manufacturing method of the optical waveguide
An optical waveguide for a touch panel which eliminates the need for alignment between the optical waveguide and a lens and which achieves the appropriate emission and reception of light beams, to provide a touch panel using the optical waveguide, and to provide a manufacturing method of the optical waveguide for a touch panel. A total distance (L) which is the sum of a distance from the center of curvature of the first lens portion 30 to the light reflecting surface 60 and a distance from the light reflecting surface 60 to the tip of the second lens portion 50 , and the radius (R) of curvature of the second lens portion 50 satisfy the following condition (A): ( L /3)−0.5< R <( L /3)+0.5 (A) where L in mm, and R in mm.
1. An optical waveguide for a touch panel, comprising:
a body;
a plurality of cores formed on a predetermined portion of a surface of the body, the plurality of cores including a light-emitting core for emitting light beams and a light-receiving core for receiving the light beams; and
an over cladding layer formed on the surface of said body while covering the plurality of cores,
the optical waveguide being provided along peripheral side surfaces of a display of the touch panel,
the light-emitting core including an end portion positioned in a first side portion of the peripheral side surfaces of said display,
the light-receiving core including an end portion positioned in a second side portion of the peripheral side surfaces of said display,
the end portion of said light-emitting core and the end portion of the light-receiving core each being formed as a first lens portion having a curved lens surface which bulges outwardly,
the curved surface of the first lens portion being formed as the lens portion to suppress the divergence of the light beams emitted from the end portion of the core in a horizontal direction along the under cladding layer or to narrow down and converge the light beams entering the end portion of the core in a horizontal direction along the under cladding layer,
the over cladding layer including an edge portion covering said first lens portion,
the edge portion of the over cladding layer extending while being bent toward said body to form a bend,
the bend including a tip portion formed as a second lens portion having a curved lens surface which bulges outwardly,
the curved surface of the second lens portion being formed as the lens portion to suppress the divergence of the light beams emitted from the end portion of the over cladding layer in a vertical direction along a plane perpendicular to the display of the touch panel or to narrow down and converge the light beams entering the end portion of the over cladding layer in a vertical direction along the plane perpendicular to the display of the touch panel,
the bend including a rear end portion on the side opposite from the second lens portion,
the rear end portion of the bend being formed as a light reflecting surface for changing the optical path of light beams so as to cause the same light beams to pass through the curved lens surface provided in the tip portion of said first lens portion and the curved lens surface provided in the tip portion of the second lens portion,
wherein a total distance (L) which is the sum of a distance from the center of curvature of the curved lens surface of said first lens portion to said light reflecting surface and a distance from the light reflecting surface to the tip of the curved lens surface of said second lens portion, and the radius (R) of curvature of the curved lens surface of said second lens portion satisfy the following condition (A):
( L/ 3) - 0.5 <R < ( L/ 3)+0.5 (A)
where L in mm, and R in mm.
2. The optical waveguide for the touch panel according to claim 1 , wherein said body is formed of an under cladding material or a metal material.
3. The optical waveguide for the touch panel according to claim 1 , wherein a thin metal film is formed on said light reflecting surface.
4. A touch panel comprising:
a display including a display screen; and
an optical waveguide including a body, a plurality of cores formed on a predetermined portion of a surface of the body, the plurality of cores including a light-emitting core for emitting light beams and a light-receiving core for receiving the light beams, and an over cladding layer formed on the surface of said body while covering the plurality of cores,
the optical waveguide being provided along peripheral side surfaces of the display of the touch panel,
the light-emitting core including an end portion positioned in a first side portion of the peripheral side surfaces of said display,
the light-receiving core including an end portion positioned in a second side portion of the peripheral side surfaces of said display,
the end portion of said light-emitting core and the end portion of the light-receiving core being formed as a first lens portion having a curved lens surface which bulges outwardly,
the curved surface of the first lens portion being formed as the lens portion to suppress the divergence of the light beams emitted from the end portion of the core in a horizontal direction along the under cladding layer or to narrow down and converge the light beams entering the end portion of the core in a horizontal direction along the under cladding layer,
the over cladding layer including an edge portion covering said first lens portion,
the edge portion of the over cladding layer extending while being bent toward said body to form a bend,
the bend including a tip portion formed as a second lens portion having a curved lens surface which bulges outwardly,
the curved surface of the second lens portion being formed as the lens portion to suppress the divergence of the light beams emitted from the end portion of the over cladding layer in a vertical direction along a plane perpendicular to the display of the touch panel or to narrow down and converge the light beams entering the end portion of the over cladding layer in a vertical direction along the plane perpendicular to the display of the touch panel,
the bend including a rear end portion on the side opposite from the second lens portion,
the rear end portion of the bend being formed as a light reflecting surface for changing the optical path of light beams so as to cause the same light beams to pass through the curved lens surface provided in the tip portion of said first lens portion and the curved lens surface provided in the tip portion of the second lens portion,
wherein the following relationship is satisfied
( L/ 3) - 0.5 <R< ( L/ 3)+0.5
where L is a total distance in millimeters which is the sum of a distance from the center of curvature of the curved lens surface of said first lens portion to said light reflecting surface and a distance from the light reflecting surface to the tip of the curved lens surface of said second lens portion, and R is the radius of curvature of the curved lens surface of said second lens portion in millimeters, and
wherein the bend provided in the edge portion of the over cladding layer which covers said first lens portion is positioned on a peripheral edge portion of the display screen of the display.