Patent Application
20050270473
1. Field of the Invention
The present invention relates to a plastic liquid crystal display device. More particularly, the invention relates to a plastic liquid crystal display having a reflector with bumps, and a fabrication method thereof.
2. Description of the Related Art
A reflective liquid crystal display does not require a backlight module as a light source, since it is so configured that an external incident light is reflected by a reflector plate provided inside the liquid crystal display, and the reflected light is utilized as a light source. This has been considered to be an effective means of reducing consumed electric power and providing thinner and brighter displays. Thus, reflective liquid crystal displays are widely used for portable devices.
Conventionally, in order to enhance reflectivity, a reflector with bumps is utilized in the reflective liquid crystal display. For example, in U.S. Pat. No. 5,204,765, Mitsui et al discloses a reflector with a number of convex portions (or bumps). The reflector with bumps can effectively control the reflective properties of the reflector to provide a bright screen image.
FIGS. 1A˜1C are schematic illustrations of the different steps on the manufacture of a conventional reflector. In
In U.S. Pat. No. 4,456,336, Chung et al discloses a glass substrate with micro-lenticular surface fabricated by a peening action, and a reflective film formed on the glass substrate to obtain a reflector. However, the profile of the micro-lenticular surface fabricated by peening is difficult to control, thereby affecting the reflective properties of the reflector.
In addition, the conventional reflector includes a glass substrate, thereby hindering brightening of the display.
The object of the present invention is to provide a method for manufacturing a plastic liquid crystal display device.
Another object of the present invention is to provide a plastic liquid crystal display having a reflector with bumps.
In order to achieve these objects, a method for manufacturing a plastic liquid crystal display device is provided. Also, the structure of the reflective liquid crystal display device is provided. A plastic substrate having a plurality of bumps on at least one surface thereof is integrally molded. A glass transition temperature (Tg) of the plastic substrate is greater than 150° C. A melt flow index (MFI) of the plastic substrate is greater than 2. A conformal reflective film on the plastic substrate with the bumps is formed. An insulating substrate opposite the plastic plate is provided. A transparent electrode is formed on an inner surface of the insulating substrate. A liquid crystal layer is inserted between the plastic substrate and the insulating substrate. In addition, the material of the plastic substrate can be PC (polycarbonate), PEN (polyethylenenaphthalate), PSF (polysulfone), PES (polyethersulfone), PAR (polyarylate), COP (cyclo olefin polymer), COC (cyclo olefin copolymer), PNB (polynorbornene), PI (polyimide), PEI (polyetherimide), PPS (polyphenylenesulfide), PEEK (polyetheretherketone) or epoxy.
The present invention improves on the prior art in that the plastic substrate with bumps is integrally molded and a reflective film is conformally formed on the plastic substrate with bumps. Moreover, the Tg of the plastic substrate is greater than 150° C. and the MFI of the plastic substrate is greater than 2. Thus, the invention can simplify the conventional manufacturing process, thereby increasing throughput and ameliorating the disadvantages of the prior art.
The present invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein:
FIGS. 1A˜1C are schematic illustrations of the different steps for the manufacture of the conventional reflector;
FIGS. 2A˜2D are sectional views according to an embodiment of the present invention; and
The present invention provides a method of forming a reflector suitable for fabricating plastic liquid crystal display (LCD) products, such as reflective plastic LCD and transflective plastic LCD. Hereinafter, as a demonstrative example, the method of forming a reflector is applied to the formation of a reflective plastic LCD.
FIGS. 2A˜2D are sectional views according to an embodiment of the present invention, which represent the different steps of the method for the manufacture of a reflector.
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It should be noted that the plastic substrate 260 of the present invention has heat-resistant, chemical-resistant, and non-deforming reproducible properties. That is, the glass transition temperature (Tg) of the plastic substrate 260 is preferably greater than 150° C. Moreover, depending on the requirements of different type display fabrication, the plastic substrate 260's glass transition temperature can be greater than 170° C., 180° C., 220° C. or 250° C. Also, the melt flow index (MFI) of the plastic substrate is preferably greater than 2. Also, depending on the requirements of different type display fabrication, the plastic substrate 260's melt flow index can be greater than 4, 6, 10 or 25. The plastic substrate 260 is transparent or opaque. The material of the plastic substrate 260 can be PC (polycarbonate), PEN (polyethylenenaphthalate), PSF (polysulfone), PES (polyethersulfone), PAR (polyarylate), COP (cyclo olefin polymer), COC (cyclo olefin copolymer), PNB (polynorbornene), PI (polyimide), PEI (polyetherimide), PPS (polyphenylenesulfide), PEEK (polyetheretherketone) or epoxy. Preferably, the material of the plastic substrate 260 is PC, PEN, PSF, PES, PAR, COP, COC, PNB, or PEI. More preferred materials are COC, COP and PNB. Here, the glass transition temperature (Tg) of part of the above plastic materials is shown as Table 1.
Generally, the higher the glass transition temperature (Tg) of the plastic material, the better the heat resistance. In this embodiment, concerning heatproof requirements, the plastic materials whose glass transition temperature (Tg) is greater than 150° C., 170° C., 180° C., 220° C. or 250° C. are employed.
Generally, the higher the melt flow index (MFI) of the plastic material, the better the flow properties during melting, thereby enabling the plastic substrate with micro-bumps to be precisely molded. The measure of the melt flow index (MFI) is according to, for example, ASTM 1238 standard, ISO 1133 standard, or performance under thermal deformation temperature plus 115° C. for heating temperature and 2.16 kg for loading, and then measuring the weight of the plastic material squeezed out from a tester for 10 minutes. In this embodiment, concerning the precise reproduction of molding, plastic materials whose melt flow index (MFI) is greater than 2, 4, 6, 10 or 25 are employed.
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As a demonstrative experiment, the reflective film 280 is respectively formed on the mother die 240 with the bumps 220 and the plastic substrate 260 with the bumps 270 (made of COC whose Tg is 180° C. and MFI is 6). Then, the scatter distribution of the reflective light according to the above is detected, and the scatter distribution of both is almost the same is founded. Thus, it is identified that the profile (or pattern) of the bumps 270 of the plastic substrate 260 manufactured by the present method is almost the same as the bumps 220 of the mother die 240.
Although the hot pressing procedure is used in this example to form an integrally molded plastic substrate 260, other molding methods can be used, such as injection molding, extrusion embossing, monomer polymerization, solution forming and teeming. Nevertheless, a heating molding method, such as hot pressing, injection molding, or extrusion embossing, is preferred. It should be noted that because the plastic substrate 260 has a heat-resistant, chemical-resistant, and non-deforming reproducible properties, the profile (or pattern) of the bumps 270 of the plastic substrate 260 is almost the same as the bumps 220 of the mother die 240 after molding. Thus, the inventive method is well suited for fabricating plastic reflective display products.
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The present invention provides a method of forming a reflective plastic liquid crystal display device having an integrally molded plastic substrate with bumps, and the structure thereof. Moreover, since the Tg of the plastic substrate is greater than 150° C. and the MFI of the plastic substrate is greater than 2, the plastic substrate has at least heat-resistant and non-deforming reproducible properties. Thus, the invention can simplify the conventional manufacturing process, thereby increasing throughput, decreasing the production cost and ameliorating the disadvantages of the prior art
Finally, while the invention has been described by way of example and in terms of the above, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 91120767 | Sep 2002 | TW | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10434202 | May 2003 | US |
| Child | 11147295 | Jun 2005 | US |
