# Patent

## Title
Method for making an optical interference type reflective panel

## Abstract

An optical-interference type reflective panel and a method for making the same are disclosed, wherein the display panel has a substrate on which multiple supporting layers are firstly formed. Then, a plurality of first conductive optical film stacks, spacing layers and multiple second conductive optical film stacks are sequentially formed on the substrate. Finally, once the spacing layers are removed, optical-interference regulators are formed. Since said supporting layers forming step is prior to the first conductive optical film stacks, a precise back-side exposing step is not necessary so that the making procedure of the panel is simplified.

## Background
This is a divisional application of an U.S. application Ser. No. 10/752,811, filed on Jan. 8, 2004 now U.S. Pat. No. 6,999,236.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical-interference type reflective panel and a method for making the same, and more particularly to a reflective panel for which a supporting layer forming step is prior to a first conductive optical film stack forming step so as to simplify the manufacturing process of the reflective panel.
2. Description of Related Art
In order to minimize the bulky size of a computer display, the flat display was developed to replace the conventional CRT display. For example, the most well known flat display is the LCD. In recent years, different kinds of LCDs have been developed by display manufacturers. Most of these manufacturers are dedicated as far as possible to reduce the power consumption of the display so that the LCD will become more suitable for portable electronic products such as cell phones, PDAs and E-books.
Inside the LCD device, the back light module consumes the most power of all the elements. To solve the problem, a reflective type panel is developed, which utilizes the external light as the light source to replace the back light module.
Whether for the conventional LCD panel or the reflective type panel, a color filtering film and a polarizing film are constructed in the panel so as to display the color images and control the direction of the light. Even though these thin films are pervious to light, a partial amount of light may be blocked or lost while light passes through these films. To overcome the light loss problem, another reflective type panel called an optical-interference panel has accordingly been developed. Based on the interference phenomenon caused when light passes through different thin films, the aforementioned optical-interference panel is able to generate the fundamental red, blue and green colors by properly creating the thin film elements. Thus, the panel is able to show color images without the use of said color filter thin film and polarizing thin film, meanwhile the light transmittance of the panel is also improved so the panel is much more suitable to be applied to the portable electronic products.
With reference to FIG. 3, a single optical-interference regulator in the aforementioned optical-interference panel includes a substrate (70), a first conductive optical film stack (71) and a supporting layer (72) formed on the substrate (70). A second conductive optical film stack (73) (also called a mechanical layer) partly covers the adjacent supporting layers (72), whereby a gap is defined between the first and second conductive optical film stacks (71, 73).
When supplying an electrical field between the two conductive optical film stacks (71, 73) by an external driving circuit (not shown), the second conductive optical film stack (73) will be slightly deformed and becomes closer to the first conductive optical film stack (71). With the different gap distances between the two conductive optical film stacks (71,73), light beams passing through the panel will have different extents of interference, so that the panel is able to show different colors.
However, the fabricating process of the conventional panel is quite complex. With reference to FIGS. 4A and 4B, the first conductive optical film stack (71) and a spacing layer (701) are sequentially formed on the substrate (70) by well known film deposition, photolithography, film etching steps etc.
A negative photo-resist layer (not shown) is then applied on the surfaces of the first conductive optical film stack (71) and the spacing layer (701). With the steps of back-side exposing and photolithography, parts of the first conductive optical film stack (71) are removed from the substrate (70). The exposed regions of the substrate (70) are provided to form multiple supporting layers (72) thereon as shown in FIG. 4C.
With reference to FIG. 4D, the second conductive optical film stack (73) is formed on all supporting layers (72) and the spacing layer (701). In FIG. 4D, after removing the spacing layer (701) from the substrate (70), a gap is accordingly defined between the first and the second conductive optical film stacks (71)(73).
In the foregoing processes, since the first conductive optical film stack (71) is formed on the substrate (70) prior to the supporting layers (72), a precise self-alignment process (back-side exposing) is involved when applying the negative photo-resist layer on the first conductive optical film stack (71) and the spacing layer (701). Thus, the entire panel manufacturing process is particularly complex.
To mitigate and/or obviate the aforementioned problem, the present invention provides a novel optical-interference type reflective panel and a method for making the same.
SUMMARY OF THE INVENTION
One objective of the present invention is to provide an optical-interference type reflective panel and a method for making the same, wherein the manufacturing procedure for the panel is simplified.
To accomplish the objective, the method has the steps of:
providing a substrate;
sequentially forming a plurality of supporting layers, first conductive optical film stacks, a spacing layer and a plurality of second conductive optical film stacks on the substrate; and
removing the spacing layer from the substrate to form optical-interference regulators on the substrate.
Because said supporting layers forming step is prior to the first conductive optical film stacks, a precise back-side exposing step is not necessary so that the fabricating procedure of the panel is simplified.
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.



BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A-1E show a manufacturing process of an optical interference panel in accordance with the present invention;
FIGS. 2A-2D show different embodiments of the first conductive optical film stacks;
FIG. 3 is a cross sectional view of a single pixel of a convention optical-interference panel; and
FIGS. 4A-4E show a conventional manufacturing process of the pixel of FIG. 3.



DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
With reference to FIGS. 1A to 1E, a manufacturing process of an optical interference panel in accordance with the present invention is disclosed. The process includes the following steps.
As shown in FIG. 1A, a plurality of the supporting layers (11) is formed on a substrate (10) that is composed of glass or macromolecule material.
In FIG. 1B, a first conductive optical film stack (12) is then formed on the substrate (10) and between adjacent supporting layers (11), wherein the first conductive optical film stack (12) also covers a partial surface of the adjacent supporting layers (11).
With reference to FIG. 1C, a spacing layer (13), which is also called a sacrificing layer, is applied on the entire substrate (10) and flattened.
With reference to FIG. 1D, a second conductive optical film (14) is formed on the spacing layer (13) and between the adjacent supporting layers (11).
In FIG. 1E, the spacing layer (12) is removed from the substrate (10), whereby the second conductive optical film (14) is sustained by the adjacent supporting layers (11) via the first conductive optical film stack (12), and a gap is defined between the first and the second conductive optical film stacks (12)(13). The structure shown in FIG. 1E is also called an optical interference regulator.
In the foregoing process, the supporting layer (11) forming is accomplished by usual exposing and photolithography steps without involving a back-side exposing technology.
With reference to FIGS. 2A-2D, said first conductive optical film stack (12) may be formed by different embodiments. In FIG. 2A, the first conductive optical film stack (12) is sequentially composed of a transparent conductive layer (121), an absorption layer (122a) and a dielectric layer (124a) according to a sequence from the bottom to the top.
As shown in FIG. 2B, the first conductive optical film stack (12) is sequentially composed of a transparent conductive layer (121b), a first dielectric layer (123b), an absorption layer (122b) and a second dielectric layer (124b).
As shown in FIG. 2C, the first conductive optical film stack (12) is sequentially composed of a first dielectric layer (123c), a transparent conductive layer (121), an absorption layer (122bc and a second dielectric layer (124c).
As shown in FIG. 2D, the first conductive optical film stack (12) is sequentially composed of a first dielectric layer (123d), an absorption layer (122d), a transparent conductive layer (121d) and a second dielectric layer (124d). Further, at least one optical reflective layer is composed in the second conductive optical film stack (14).
Since the manufacturing process of the present invention does not need a precise alignment step, the supporting layers (11) are partly overlapped by the first conductive optical film stack (12). Thus, said second conductive optical film stack (14) is accordingly formed above the first conductive optical film stack (12).
With the foregoing description, the panel manufacturing procedure is simplified because the precise alignment step is not required any more. Accordingly, the producing efficiency is able to be improved.
It is to be understood, however, 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.

## Claims

1. A method for making an optical interference reflective panel, the method comprising the steps of:
providing a substrate;
sequentially forming a plurality of supporting layers, a plurality of first conductive optical film stacks, a spacing layer and a plurality of second conductive optical film stacks on the substrate; and
removing the spacing layer from the substrate to form optical-interference regulators on the substrate.

2. The method as claimed in claim 1, the method further comprising the steps of:
forming the plurality of supporting layers on the substrate;
forming the first conductive optical film stacks on the substrate and between adjacent supporting layers;
forming the spacing layer on the substrate, wherein the spacing layer is flattened;
forming the second conductive optical film stacks above the adjacent supporting layers; and
removing the spacing layer, wherein once the spacing layer has been removed from the substrate, a gap is defined between the first and the second conductive optical film stacks and the second conductive optical film stack is sustained by the adjacent supporting layers.

3. The method as claimed in claim 1, wherein the first conductive optical film stack covers a part of the adjacent supporting layers, and the second conductive optical film stack is formed above regions where the first conductive optical film stack overlaps the adjacent supporting layers.

4. The method as claimed in claim 2, wherein the first conductive optical film stack covers a part of the adjacent supporting layers, and the second conductive optical film stack is formed above regions where the first conductive optical film stack overlaps the adjacent supporting layers.

5. The method as claimed in claim 1, wherein the substrate is composed of glass or macromolecule material.

6. The method as claimed in claim 2, wherein the substrate is composed of glass or macromolecule material.

7. The method as claimed in claim 1, wherein the first conductive optical film stack is composed of a transparent conductive layer, an absorption layer and at least one dielectric layer.

8. The method as claimed in claim 2, wherein the first conductive optical film stack is composed of a transparent conductive layer, an absorption layer and at least one dielectric layer.

9. The method as claimed in claim 1, wherein the second conductive optical film stack contains at least one optical reflective layer therein.

10. The method as claimed in claim 2, wherein the second conductive optical film stack contains at least one optical reflective layer therein.