Input device

• US 8,189,127 B2
• Filed: 01/22/2008
• Issued: 05/29/2012
• Est. Priority Date: 02/22/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Kenichi, Tanabe, Koji
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Chung, David Y
• Application Number:
  US12/017,492
• Publication Number:
  US 20080204611A1
• Time in Patent Office: 1,589 Days
• Field of Search: 349/12, 349/96, 349/117, 349/118, 349/119, 349/120, 349/121
• US Class Current: 349/12
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133635 Multifunctional compensators
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

According to the input device of the present invention, phase-difference plate (11) with ¼ wavelength is disposed on the top surface of upper substrate (1) of touch panel (12). As a result of passing through phase-difference plate (11), lamplight 9a that illuminates LCD element (8) goes outside as outgoing-light 9c with a phase-shift of ¼ wavelength. With the structure above, a user wearing polarized sunglasses—even if they have an absorption axis in a direction the same as that of lamplight 9a—can easily recognize the displays shown by LCD element (8) on the back surface of touch panel (12). The structure offers a user-friendly input device with good visibility of LCD element (8).

Claims

1. An input device for use by a user wearing a polarized glass comprising:

a touch panel having a light-transmissive upper substrate with an upper conductive layer disposed on a bottom surface of the light-transmissive upper substrate, and a light-transmissive lower substrate with a lower conductive layer disposed on a top surface of the light-transmissive lower substrate so as to face the upper conductive layer at predetermined spaced intervals;

a liquid crystal display element disposed below the light-transmissive lower substrate; and

a polarizing plate disposed between the lower conductive layer and the liquid crystal display element,

wherein at least any one of the light-transmissive upper substrate and the light-transmissive lower substrate is formed as a phase-difference plate with ¼

wavelength so that the phase-difference plate with ¼

wavelength is located close to the touch panel and over the polarizing plate,

wherein the input device is absent a polarizing plate disposed over the phase-difference plate,

the phase-difference plate provides outgoing-light with a phase-shift of ¼

wavelength,

a polarization direction of the polarizing plate is different from a polarization direction of the polarized glass, and

an outgoing-light from the liquid crystal display element changes to a circular polarized light, allowing the displays of the liquid crystal display element to be recognized even when a polarization direction of the polarizing plate has an absorption axis in the same polarization direction of the polarized glass.