INPUT DEVICE

• US 20080204611A1
• Filed: 01/22/2008
• Published: 08/28/2008
• Est. Priority Date: 02/22/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Kenichi, Tanabe, Koji
• Granted Patent: US 8,189,127 B2
• Time in Patent Office: Days
• 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 comprising:

a light-transmissive upper substrate with an upper conductive layer disposed on a bottom surface;

a light-transmissive lower substrate with a lower conductive layer disposed on a top surface so as to face the upper conductive layer at predetermined spaced intervals; and

a liquid crystal display element disposed below the lower substrate,

wherein a phase-difference plate with ¼

wavelength is disposed on a top surface of the upper substrate or on a bottom surface of the lower substrate.

2. The input device of claim 1, wherein, with no use of the phase-difference plate, at least any one of the upper substrate and the lower substrate is formed as a phase-difference plate with ¼

wavelength.