U.S. patent application number 10/898076 was filed with the patent office on 2005-01-27 for method for manufacturing a light guide plate mold.
Invention is credited to Chen, Ga-Lane, Yu, Tai-Cherng.
Application Number | 20050016855 10/898076 |
Document ID | / |
Family ID | 34076394 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016855 |
Kind Code |
A1 |
Chen, Ga-Lane ; et
al. |
January 27, 2005 |
Method for manufacturing a light guide plate mold
Abstract
A method for manufacturing a light guide plate mold includes the
steps of: forming a photo-resist film (210) on a substrate (200);
disposing a gray level mask (220) having a predetermined pattern
over the substrate, illuminating the photo-resist film through the
gray level mask by illuminating rays; developing the photo-resist
film to form a photo-resist pattern (211) on the substrate; etching
simultaneously the substrate and the photo-resist pattern to form a
stamper (201); coating a metal-plating layer (230) over the
stamper; electroforming the stamper coated with the metal-plating
layer to form a master stamper (240); and stripping the
metal-plating layer from the master stamper to attain the light
guide plate mold. The method is highly precise and simple.
Inventors: |
Chen, Ga-Lane; (Fremont,
CA) ; Yu, Tai-Cherng; (Tu-chen, TW) |
Correspondence
Address: |
WEI TE CHUNG
FOXCONN INTERNATIONAL, INC.
1650 MEMOREX DRIVE
SANTA CLARA
CA
95050
US
|
Family ID: |
34076394 |
Appl. No.: |
10/898076 |
Filed: |
July 23, 2004 |
Current U.S.
Class: |
205/70 ;
205/79 |
Current CPC
Class: |
C25D 1/10 20130101 |
Class at
Publication: |
205/070 ;
205/079 |
International
Class: |
C25D 001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2003 |
TW |
92120072 |
Claims
We claim:
1. A method for manufacturing a light guide plate mold, comprising
the steps of: forming a photo-resist film on a substrate; disposing
a gray level mask having a predetermined pattern over the
substrate, and illuminating the photo-resist film through the gray
level mask; developing the photo-resist film to form a photo-resist
pattern on the substrate; etching simultaneously the substrate and
the photo-resist pattern to form a stamper; coating a metal-plating
layer over the stamper; and electroforming the stamper coated with
the metal-plating layer to form a master stamper; and stripping the
metal-plating layer from the master stamper to attain the light
guide plate mold.
2. The method according to claim 1, wherein the photo-resist
pattern formed by the developing step comprises a plurality of
V-shaped grooves.
3. The method according to claim 1, wherein the illumination is by
yellow rays.
4. The method according to claim 1, wherein the illumination is by
ultraviolet rays.
5. The method according to claim 1, wherein the stamper formed by
the etching step has a plurality of V-shaped grooves thereon.
6. The method according to claim 1, wherein the step of etching
comprises dry-etching.
7. The method according to claim 6, wherein the dry-etching is
plasma dry-etching.
8. The method according to claim 1, further comprising the step of
forming a thin film layer before forming the photo-resist film on
the substrate.
9. The method according to claim 1, wherein the photo-resist film
is formed by a spin-coating process.
10. The method according to claim 1, wherein the photo-resist film
is formed by a dip-coating process.
11. The method according to claim 1, wherein the photo-resist film
is formed by a roll-coating process.
12. The method according to claim 1, wherein the photo-resist film
is formed by a spray-coating process.
13. The method according to claim 1, wherein the photo-resist film
is formed by an extrusion slot-coating process.
14. The method according to claim 1, wherein the photo-resist film
comprises positive photo-resist material.
15. The method according to claim 1, wherein the photo-resist film
comprises negative photo-resist material.
16. A method for manufacturing a light guide plate mold, comprising
the steps of: forming a photo-resist film on a substrate; disposing
a gray level mask having a predetermined pattern over the
substrate, and illuminating the photo-resist film through the gray
level mask; developing the photo-resist film to form a photo-resist
pattern on the substrate; etching the substrate to form a stamper
having a first set of densely arranged V-shaped slots in an upper
face thereof; coating a metal-plating layer over the stamper; and
electroforming the stamper coated with the metal-plating layer to
form a master stamper; and stripping the metal-plating layer from
the master stamper to attain the light guide plate mold; wherein
said master stamper defines a second set of densely arranged
V-shaped slots in an upper face thereof corresponding to the first
set of densely arranged V-shaped slots.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to methods for manufacturing
light guide plate molds, and particularly to a method of
manufacturing a light guide plate mold using photolithography
technology.
[0003] 2. The Prior Art
[0004] In a liquid crystal display, a backlight module is always
used to provide a planar light source for illuminating the liquid
crystal display. In general, the backlight module includes a light
source and a light guide plate, the light source being located
adjacent to one side of the light guide plate. The light guide
plate transfers light beams emitted from the light source to planar
light beams, and directs them to a liquid crystal panel of the
liquid crystal display.
[0005] A plurality of printing-dots is distributed on a bottom
surface of the light guide plate for improving the uniformity of
the backlight module. The printing-dots scatter and reflect the
light beams emitted from the light source to uniform planar light
beams. The shape, the density and the size of the printing-dots are
configured according to requirements of different applications. For
example, the printing-dots can have square, circular, or
diamond-shaped profiles.
[0006] Brightness is another important factor for the backlight
module. A conventional method for increasing the brightness of the
backlight module is by providing two prism sheets. The two prism
sheets are made of transparent material. One surface of each prism
sheet includes a plurality of parallel V-shaped grooves, for
collimating the planar light beams. The V-shaped grooves of the two
prism sheets are disposed orthogonally to each other. The two prism
sheets can efficiently improve the brightness of the backlight
module. However, the cost of the backlight module is high due to
the two expensive prism sheets, and the assembly is complex.
[0007] FIG. 8 shows a conventional surface light source module. The
surface light source module 100 includes a light tube 110, a light
tube shield 111, a light guide plate 120, a reflective sheet 150, a
prism sheet 130, and a diffuser 140. The reflective sheet 150 is
disposed below the light guide plate 120. The prism sheet 130 and
the diffuser 140 are stacked on the light guide plate 120 in that
order. A plurality of printing-dots 121 is distributed on the
bottom surface of the light guide plate 120, for increasing the
uniformity of light beams output from the surface light source
module. The printing-dots 121 can have square, elliptic,
rectangular or semi-circular profiles. A plurality of V-shaped
grooves 122 provided on a top surface can collimate light beams
instead of one prism sheet. The surface light source module 100
just needs one prism sheet 130 in order to obtain the same effect
as two prism sheets. Therefore, the cost of the surface light
source module 100 is reduced, and it is easily assembled.
[0008] A conventional method for manufacturing the V-shaped grooves
is by way of mechanical machining technology. The mechanical
machining technology includes the steps of: forming a stamper
having V-shaped grooves machined by a precision cutting tool;
electro-forming the stamper to form a light guide plate mold having
reverse V-shaped grooves according to that of the stamper; forming
a light guide plate having V-shaped grooves by the injection
molding technology or hot embossing technology. However, the
machining precision is low due to inherent mechanical error and
wearing out of the cutting tool.
[0009] A manufacturing method of a light guide plate mold is
described in China Pat. Pub. No. 1,372,161A. The manufacturing
method can form a plurality of micro structures on a surface of the
light guide plate mold, the micro structures being arcuate
protrusions or concavities. In order to form a plurality of
V-shaped grooves, the whole process needs to be repeated several
times. Therefore, the process of forming V-shape grooves is unduly
complicated, and the precision of the V-shaped grooves is low due
to compounding of inherent error with each repeat of the
process.
[0010] An improved manufacturing method for a light guide plate
mold that overcomes the above-mentioned disadvantages is
desired.
SUMMARY OF THE INVENTION
[0011] An object of the present invention is to provide a
manufacturing method for a light guide plate mold which is highly
precise and simple.
[0012] In order to achieve the object set forth, a method for
manufacturing a light guide plate mold in accordance with the
present invention, comprises steps of: forming a photo-resist film
on a substrate; disposing a gray level mask having a predetermined
pattern over the substrate, illuminating the photo-resist film
through the gray level mask by illuminating rays; developing the
photo-resist film to form a photo-resist pattern on the substrate;
etching simultaneously the substrate and the photo-resist pattern
to form a stamper; coating a metal-plating layer over the stamper;
electroforming the stamper coated with the metal-plating layer to
form a master stamper; and stripping the metal-plating layer from
the master stamper to attain the light guide plate mold. The light
guide plate mold has high precision, and the manufacturing method
is simple.
[0013] Other objects, advantages and novel features of the
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 shows a step of coating a photo-resist layer on a
substrate in a method for manufacturing a light guide plate mold
according to the present invention;
[0015] FIG. 2 shows a step of exposing the photo-resist layer using
a gray level mask in the method for manufacturing the light guide
plate mold;
[0016] FIG. 3 shows a developing step in the method for
manufacturing the light guide plate mold;
[0017] FIG. 4 shows an etching step for forming a stamper in the
method for manufacturing the light guide plate mold;
[0018] FIG. 5 shows a step of coating a metal-plating layer onto a
surface of the stamper in the method for manufacturing the light
guide plate mold;
[0019] FIG. 6 shows an electroforming step of forming a master
stamper in the method for manufacturing the light guide plate
mold;
[0020] FIG. 7 is a schematic view of the master stamper; and
[0021] FIG. 8 is a schematic view of a conventional surface light
source module.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] FIGS. 1 to 7 are views illustrating stages in a method for
manufacturing a light guide plate mold according to the present
invention. The manufacturing method includes the following
steps:
[0023] (1) forming a photo-resist film 210 on a substrate 200, as
shown in FIG. 1;
[0024] (2) disposing a gray level mask 220 having a predetermined
pattern over the substrate 200, illuminating the photo-resist film
210 through the gray level mask 220, as illustrated in FIG. 2;
[0025] (3) developing the photo-resist film 210 to form a
photo-resist pattern 211 on the substrate 200, as shown in FIG.
3;
[0026] (4) etching simultaneously the substrate 200 and the
photo-resist pattern 211 to form a stamper 201 with a plurality of
V-shaped grooves 202, as illustrated in FIG. 4;
[0027] (5) coating a metal-plating layer 230 over the stamper 201,
as shown in FIG. 5;
[0028] (6) electroforming the stamper 201 coated with the
metal-plating layer 230 to form a master stamper 240, as
illustrated in FIG. 6; and
[0029] (7) stripping the metal-plating layer 230 from the master
stamper 240 to attain a light guide plate mold, as shown in FIG.
7.
[0030] In FIG. 1, the photo-resist film 210 coating on the
substrate 200 comprises positive or negative photo-resist material.
The process for forming the photo-resist film 210 may be a
spin-coating process, a dip-coating process, a roll-coating
process, a spray-coating process, an extrusion slot-coating
process, etc. Furthermore, before coating the photo-resist film
210, a thin film layer (not shown) is formed on the substrate 200
to improve the smoothness of the substrate 200.
[0031] In FIG. 2, the gray level mask 220 is made of a high-energy
beam sensitive glass. The gray level mask 220 suitable for
photolithography is constructed of a transparent glass substrate
which supports plural levels of materials having different optical
transmissivities. The mask is fabricated with the aid of a
photoresist structure which is etched in specific regions by
photolithographic masking to enable selective etching of exposed
regions of the level of materials of differing optical
transmissivities. The high-energy beam sensitive glass is a
composite crystal of silver-alkali-halide. For example, by exposing
the substrate 200 having the photo-resist film 210 to yellow light,
ultraviolet light, or ion beams, different depth levels can be made
on the substrate 200 by using the gray-level mask 220.
[0032] In FIG. 3, the process for developing the photo-resist film
210 can be a soaking process, a spraying process, etc. The remained
photo-resist pattern 211 is a plurality of V-shaped grooves which
is the same pattern as the pattern of the grey-level mask 220.
[0033] The substrate 200 and the photo-resist pattern 211 are
etched simultaneously with dry etching techniques to define the
stamper 201 with a plurality of V-shaped grooves 202. Plasma gases
are usually used as a driving gas because they have a high
excitation energy. The plasma dry etching technology has the
advantage of anisotropic etching for most etching materials.
[0034] In FIG. 5, the process for coating the metal-plating layer
230 on the stamper 201 may be a sputtering process, an evaporating
process, or a spraying process. Various metals can be used as the
material of the metal-plating layer 230. However, nickel (Ni) is
most preferred in view of the desired uniformity and mechanical
properties of the metal-plating layer 230.
[0035] In FIGS. 5 and 6, after the electroforming step and the
stripping step, V-shaped grooves are transferred from the stamper
201 to the light guide plate mold.
[0036] However, the method for manufacturing a light guide plate
mold can be not only used to form a light guide plate mold with
V-shaped grooves. Other patterns also can be defined according to
the particular configured pattern of the gray level mask 220 and
the etching process.
[0037] Further, it is to be understood that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed._
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