1. Field of the Invention
The present invention relates to a keypad, and more particularly, to a keypad with a flexible light guide plate.
2. Description of the Related Art
Along with the continuous technology development and the growth of the need for the convenience of portable products in the consumer market, the handheld electronic apparatus is designed to be lighter, thinner, shorter, and more compact and capable of providing powerful functions. In general, depending on the functions it provides, the handheld electronic apparatus are generally classified into cell phones, electronic dictionaries, Personal Digital Assistants (PDAs), and handheld game consoles.
For example, the cell phone mainly comprises a main body, a display unit, and a keypad. Wherein, the main body is usually a data processing module, and the display unit is usually a Liquid Crystal Display Module (LCM). The display unit is usually disposed inside the main body, and the display area of the display unit is exposed from the main body. The display unit displays the images, patterns, and the texts. In addition, the keypad usually disposed on the main body works as an operation interface of the handheld electronic apparatus.
To help users recognize the text or pattern on the keypad under a condition of insufficient luminance, a set of backing light source is commonly disposed under the keypad, such that the users can conveniently recognize the text or pattern on the keypad. In addition, the backing light source may be a Light Emitting Diode (LED) or an Electro-Luminescent Device (ELD). The detail structure of the conventional keypad is described in greater detail hereinafter.
FIG. 1 is a schematic sectional view of a conventional keypad. Referring to FIG. 1, the conventional keypad 100 comprises a first substrate 110, a second substrate 120, a key pattern, 130, a third substrate 140, and a light source 150 disposed on the third substrate 140. Wherein, the light source 150 is a Light Emitting Diode (LED). Since the light source 150 is disposed under the first substrate 110, the second substrate 120, and the key pattern 130. To be emitted from the surface of the second substrate 120, the light emitted by the light source 150 has to sequentially pass through the first substrate 110 and the second substrate 120. However, the first substrate 110 is usually made of a material such as PC (Phosphatidyl Cholineor) or ABS (Acrylonitrile Butadiene Styrene), and the second substrate 120 is usually made of a material such as rubber. In other words, the display brightness of the conventional keypad 100 is confined by the materials of the key pattern 130, the first substrate 110, and the second substrate 120. Accordingly, if the display brightness of the conventional keypad 100 is insufficient or not uniformly distributed, the user cannot easily recognize the text or pattern on the keypad. To resolve this problem, an easy solution is to increase the quantity of the light sources 150 disposed on the conventional keypad 100. However, such method inevitably increases electric power consumption of the handheld electronic apparatus.
In addition, although the keypad 100 provides more uniformly distributed brightness when it is comprised of the ELDs, since the ELDs are also disposed under the first substrate 110 and the second substrate 120, the light emitted by the ELDs is still confined by the first substrate 110 and the second substrate 120, the conventional keypad 100 is not able to provide an uniformly distributed brightness.