WO2006126769A1

WO2006126769A1 - Super-thin type keypad emitting light

Info

Publication number: WO2006126769A1
Application number: PCT/KR2005/004608
Authority: WO
Inventors: Woon Ho Baek; Byung Dong Chun; In Shik Park; Kyoung Hyoun Lee
Original assignee: Hanwool Information Tech Co Ltd
Current assignee: Hanwool Information Tech Co Ltd
Priority date: 2005-05-24
Filing date: 2005-12-28
Publication date: 2006-11-30
Anticipated expiration: 2007-11-24
Also published as: KR100514759B1; KR20070061756A

Abstract

A super thin type light emitting keypad formed with an EL (Electro Luminescence) device at an upper surface of a rear surface layer formed thereunder with a protrusion such that destruction caused by deformation of EL device can be prevented, light emitting efficiency and luminance can be increased, and an elastic substrate is disposed to remarkably improve click feeling and switching accuracy, and the EL device is equipped with a dispersion layer, a static electricity shield layer and a noise stop layer to enable to minimize influence of static electricity or electromagnetic wave and to provide a uniform light emitting surface.

Description

SUPER-THIN TYPE KEYPAD EMITTING LIGHT

Technical Field

[1] The present invention relates to a super thin type light emitting keypad, and more particularly to a super thin type light emitting keypad formed with an EL (Electro Luminescence) device at an upper surface of a rear surface layer formed thereunder with a protrusion such that destruction caused by deformation of EL device can be prevented, light emitting efficiency and luminance can be increased, and an elastic substrate is disposed to remarkably improve click feeling and switching accuracy, and the EL device is equipped with a dispersion layer, a static electricity shield layer and a noise stop layer to enable to minimize influence of static electricity or electromagnetic wave and to provide a uniform light emitting surface.

[2]

Background Art

[3] Generally, a light emitting keypad is applied to communication devices such as mobile phones for practical use as a switch for conducting various supplemental functions including signal generation, and particularly for conducting functions to distinguish and select keys for inputting characters or symbols at night or in a dark area, and concomitant with acceleration of thinning of the mobile phones, development of super thin light emitting keypads is keeping pace therewith.

[4]

[5] A light emitting keypad of existing LED (Light Emitting Diode) method used as light source cannot be manufactured in thin type due to fabrication constraints and is manufactured in a relatively thick structure. Another drawback of a light emitting keypad by the LED method is that a large amount of power is consumed to shorten the life of a battery. Still another drawback is that light emitting uniformity cannot be maintained according to arranged position of LED resulting in a difficulty in design.

[6]

[7] In order to cope with the limit of super-thinning of light emitting keypad by the existing LED method, development of super thin light emitting keypad applied with an EL lamp light emitting method (hereinafter referred to as EL method) has been required.

[8]

[9] FIG.1 is a cross-sectional view of a known light emitting keypad by EL method for complementing the aforementioned drawbacks. [11] Referring to FIG.1, the keypad is disposed with a key top (110), a metal dome sheet

(120), a Printed Circuit Board (PCB.130), while the EL metal dome sheet (120) is made of an EL sheet (121), a metal dome (123) and a base tape (122) to thereby enable to realize a super thin structure and a reduced power consumption.

[12]

[13] Now, functional side of the metal dome keypad by the EL method will be described.

[14]

[15] When the key top (110) is depressed, fixed contact terminals at the metal dome

(123) and the Printed Circuit Board (PCB) are made to be interconnected by a protrusion (111) disposed at a rear surface of the key top (110) and switched for operation.

[16]

[17] However, there is a problem in the light emitting keypad of EL method according to the prior art thus described in that the EL sheet (121) is continuously depressed and pressurized by the protrusion (111), resulting in a high risk of damage to and destruction of the EL sheet, a degenerated credibility of the EL sheet and reduced feeling of clicking.

[18]

[19] There is another problem in that the EL sheet (121) is positioned thereon with a relatively thick key top (110) made of silicon of low light transmission factor such that light output efficiency is remarkably reduced and luminance is decreased as well.

[20]

[21] Meanwhile, still another problem is that performance of the product is greatly eroded if influenced by static electricity and electromagnetic wave. Particularly, lights are generally coming from particles of a light emitting body each having an approximate diameter of 20~50μm and because of existence of shade between particles, there may arise a problem in the uniformity of colors and luminance.

[22]

Disclosure of Invention Technical Problem

[23] Accordingly, the present invention is conceived to solve the aforementioned problems and it is an object of the present invention to provide a super thin type light emitting keypad formed with an EL (Electro Luminescence) device at an upper surface of a rear surface layer formed thereunder with a protrusion such that destruction caused by deformation of EL device can be prevented, light emitting efficiency and luminance can be increased, and an elastic substrate is disposed to remarkably improve click feeling and switching accuracy, and the EL device is equipped with a dispersion layer, a static electricity shield layer and a noise stop layer to enable to minimize influence of static electricity or electromagnetic wave and to provide a uniform light emitting surface. [24] [25]

Technical Solution [26] To achieve the object, the present invention provides a super thin type light emitting keypad comprising: an ink layer formed underneath an elastic substrate; an EL device formed underneath the ink layer; and a rear surface layer disposed underneath the EL device and having a protrusion. [27] [28] The keypad further comprises: a contact terminal; and a Printed Circuit Board

(PCB) disposed on an upper surface of the contact terminal with a metal dome positioned from the contact terminal. [29] [30] The keypad further comprises an adhesive layer between the EL device and the rear surface layer. [31] [32] The EL device comprises; an EL system for illuminating lights and at least one layer or more out of a dispersion layer at an upper surface or a lower surface of the EL system, a static electricity shield layer and a noise stop layer. [33] [34] Preferably, at least one or more out of the ink layer, the EL device, the rear surface layer and the protrusion is formed by screen printing method. [35] [36] Preferably, the protrusion is formed to the rear surface layer by thermo-compression method. [37]

[38] Preferably, the protrusion and the rear surface layer are integrally formed.

[39]

[40] Preferably, the elastic substrate is a polycarbonate.

[41]

Advantageous Effects

[42] Because of the characteristic structure thus described, the present invention provides a super thin type light emitting keypad formed with an EL (Electro Luminescence) device at an upper surface of a rear surface layer formed thereunder with a protrusion such that destruction caused by deformation of EL device can be prevented, light emitting efficiency and luminance can be increased, and an elastic substrate is disposed to remarkably improve click feeling and switching accuracy, and the EL device is equipped with a dispersion layer, a static electricity shield layer and a noise stop layer to enable to minimize influence of static electricity or electromagnetic wave and to provide a uniform light emitting surface. [43]

Brief Description of the Drawings [44] FIG.1 is a cross-sectional view of a light emitting keypad by EL method according to the prior art. [45] FIG.2 is a cross-sectional view of a super thin light emitting keypad according to the present invention. [46] FIG.3 is a cross-sectional view of another embodiment of a super thin light emitting keypad according to the present invention. [47] FIG.4 is a cross-sectional view of a super thin light emitting keypad of EL device according to the present invention. [48] [49]

Best Mode for Carrying Out the Invention [50] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. [51] [52]

Mode for the Invention

[53] FIG.2 is a cross-sectional view of a super thin light emitting keypad according to the present invention. Referring to FIG.2, the super thin light emitting keypad according to the present invention includes an ink layer (2) formed underneath an elastic substrate (1), an EL device (3) formed underneath the ink layer (2), and a rear surface layer (6) formed underneath the EL device (3) and equipped with a protrusion (6), where an adhesive layer (4) is further disposed between the EL device (3) and the rear surface layer (5) for the super thin light emitting keypad.

[54]

[55] The elastic substrate (1) made of elastic material improves click feel on account of its elasticity, and enables an easy and smooth keypad manipulation even with a little force applied thereto. In other words, if a user depresses a predetermined key, an area for the predetermined key is particularly dented so that unwanted key areas are prevented from being dented and switched to thereby enable to effect an accurate switching. Furthermore, if the user releases a pressure to the depressed key, the key is naturally returned to its original shape by the elasticity. Although a separate elastic layer may be disposed, manufacturing process can be further simplified because the elastic substrate also functions as an elastic layer to make it possible to manufacture a thin keypad. Material for the elastic substrate is not limited as long as it has elasticity. For example, resins such as polycarbonate (PC), polyethylene terephthalate (PET) and polyurethane may be selected, and more preferably, PC is adequate for the elastic substrate, and film-shaped injection-molded PC is desirable. There is no limit to the thickness of the substrate (1) and for the sake of super thin type, the thickness is preferred to be in the range of 100~400μm. Furthermore, it is preferred to have an excellent light permeability.

[56]

[57] The ink layer (2) designed to indicate a key for the keypad embodies a front shape of the keypad. The ink layer is formed by coating keypad ink by way of spray or screen printing method at a bottom surface of the substrate (1), and it is preferred that the thickness of the ink layer be 5~ lOμm.

[58]

[59] The EL device (3) which is an illuminating region is not particularly restricted in structure and fabricating method thereof, and structure and fabricating method of the EL device (3) disclosed or used for the technical field of the present invention may be selected without any restriction. Preferably, the thickness of the EL device is 100 ~150μm in consideration of super thin structure and illuminating function. The EL device is placed adjacent to the front of the keypad to enable to maximize the light emitting efficiency. Furthermore, luminance can be relatively increased due to no light loss caused by a key top made of silicon material according to the prior art.

[60]

[61] Now, the EL device (3) and fabricating method thereof will be described with reference to FIG.4 according to the preferred embodiment of the present invention.

[62]

[63] The rear surface layer (5) is disposed thereunder with a protrusion (6) to provide a smooth keypad manipulation and click feeling and effective switching. There is no limit to the material for the rear surface layer (5). However, preferably, silicon and a high polymer resin may be selected.

[64]

[65] One of the methods of forming the protrusion (6) underneath the rear surface layer

(5) is to arrange a protrusion (6) separately and glue it to the rear surface layer (5), but preferably, the protrusion (6) and the rear surface layer (5) are integrally formed to thereby increase the strength and durability. In other words, liquid silicon, film silicon or high polymer resin is compression-molded to the rear surface layer (5) or the protrusion (6) under 100-150 degrees Celsius, or by photolithography method, ultraviolet hardening or infrared hardening ink is screen-printed for formation.

[66]

[67] One example of forming the rear surface layer (5) to the EL device (3) is to provide a separate adhesive layer (4) for mutual adhesion, which is most preferred as this method enhances an adhesiveness. The adhesive material is not limited but printing adhesive used for screen printing or an adhesive tape may be employed. More preferably, a primer used for adhesiveness is suitable.

[68]

[69] FIG.3 is a cross-sectional view of a super thin light emitting keypad of EL device according to the present invention.

[70]

[71] In other words, the present invention comprises a super- thin light emitting keypad further including a printed circuit board (8) disposed thereon with metal domes (82) and contact terminals (81) under the rear surface layer (5), and each dome (82) and contact terminal (81) spaced a predetermined distance apart thereon. The printed circuit board (8) is disposed thereon with metal domes (82) and contact terminals (81).

[72]

[73] If a key of the keypad is depressed by a user, an area of a particular key at the elastic substrate (1) is elastically deformed to allow a relevant protrusion (6) to apply a pressure to the metal dome (82) of the printed circuit board (8), and as a result, the metal dome (82) contacts the contact terminal (81) for switching.

[74]

[75] FIG.4 is a cross-sectional view of a super thin light emitting keypad of EL device according to an embodiment of the present invention. FIG. 4 is only an exemplary drawing and it should be apparent that modification of the layered order of illustrated structure and partial omission thereof all belong to the scope of the present invention.

[76]

[77] It is most appropriate that the EL device (3) according to the present invention is constructed as illustrated in FIG.4.

[78]

[79] In other words, the EL device (3) is fabricated by being layered on the ink layer (2) in sequence of a static electricity shield layer (31), a dispersion layer (32), an insulation layer (33), a front electrode layer (34), a light emitting layer (35), a dielectric layer (36), a rear electrode layer (37), an insulation layer (38), a noise stop layer (39) and an insulation layer (40). The front electrode layer (34), the light emitting layer (35), the dielectric layer (36) and the rear electrode layer (37) comprise an EL system which is a light emitting structure of the EL device (3).

[80]

[81]

[82] Preferably, the fabricating method of the EL device (3) is to form the EL device (3) underneath the ink layer (2) by way of screen printing method for thin film structure.

[83]

[84] In the above construction, the forming of layers other than the static electricity shield layer (31), the dispersion layer (32) and the noise stop layer (39) is a well- known art in the related field and explanation thereto will not be elaborated herein but the forming of the static electricity shield layer (31), the dispersion layer (32) and the noise stop layer (39) is the feature of the present invention such that detailed description thereto will be made hereunder.

[85]

[86] The static electricity shield layer (31) is formed to guard against damage of circuit parts and EL system caused by generation of external static electricity and serves to discharge the generated static electricity to the PCB (8) or a device case via a ground terminal. Preferably, the static electricity shield layer (31) is made of material of high electric conductivity such as carbon, copper, silver, gold or the like.

[87]

[88] The dispersion layer (32) functions to help improve the dispersion of light generated by the light emitting layer (35). Preferably, the dispersion layer (32) is made of material of good light transmission factor and may include various materials for improving dispersion of light. Preferably, various pigments, glass beads, calcium carbonite and the like may be selected.

[89]

[90] The noise stop layer (39) functions to block the noise generated in the course of operating the EL device (3) by way of alternating current (AC) source. The noise stop layer (39) is preferred to be disposed at a bottom surface of the EL device (3). The noise may be effectively eliminated by using material having a high electric conductivity.

[91] The materials having a high electric conductivity include carbon, copper, silver, gold or the like, but they are not limited thereto.

[92]

[93] The embodiments described above are intended to illustrate the present invention and should not be construed as limiting the invention set forth in the appended claims or reducing the scope thereof, but rather that various changes or modifications thereof are possible without departing from the spirit of the invention.

[94] [95] In other words, a fabricating method reverse from that of the present invention is also possible without departing from the spirit of the invention. In other words, a rear surface layer may be first formed and then an elastic layer, an EL device (An inner structure in reverse sequence is also possible), an ink layer and an elastic substrate may be sequentially stacked without departing from the spirit and scope of the present invention. Furthermore, the EL sheet may be specifically formed at a predetermined region under the ink layer.

[96]

Industrial Applicability

[97] Accordingly, the present invention having the features thus described provides a super thin type light emitting keypad formed with an EL (Electro Luminescence) device at an upper surface of a rear surface layer formed thereunder with a protrusion such that destruction caused by deformation of EL device can be prevented, light emitting efficiency and luminance can be increased, and an elastic substrate is disposed to remarkably improve click feeling and switching accuracy, and the EL device is equipped with a dispersion layer, a static electricity shield layer and a noise stop layer to enable to minimize influence of static electricity or electromagnetic wave and to provide a uniform light emitting surface. For that reason, the present invention applied to communication devices such as mobile phones can perform a signal generation and various supplementary functions, and particularly can be adequately used for a keypad having a function of distinguishing numbers or characters in the dark or at night.

[98]

[99]

[100]

Claims

[1] A super thin type light emitting keypad comprising: an ink layer formed underneath an elastic substrate; an EL device formed underneath the ink layer; a plurality of elastic layers formed underneath the EL device; and a rear surface layer disposed underneath the elastic layers and having a protrusion.

[2] The keypad as defined in claim 1 further comprising a Printed Circuit Board

(PCB) disposed under the rear surface layer and equipped with contact terminals and metal domes each spaced a predetermined distance apart from the contact terminal.

[3] The keypad as defined in claim 1 or 2 further comprising an adhesive layer between the EL device and the elastic layers.

[4] The keypad as defined in claim 1 or 2, wherein the EL device comprises; an EL system for illuminating lights and at least one or more layers out of a dispersion layer at an upper surface or a lower surface of the EL system, a static electricity shield layer and a noise stop layer.

[5] The keypad as defined in claim 1 or 2, wherein at least one layer or more out of the ink layer, the EL device, the elastic layers, the rear surface layer and the protrusion is formed by screen printing method.

[6] The keypad as defined in claim 1 or 2, wherein the protrusion is formed to the rear surface layer by thermo-compression forming method.

[7] The keypad as defined in claim 1 or 2, wherein the protrusion and the rear surface layer are integrally formed.

[8] The keypad as defined in claim 1 or 2, wherein the elastic substrate comprises polycarbonate.