Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-05-17
2004-11-02
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
Reexamination Certificate
active
06812983
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a retardation plate and a fabrication method thereof, and also relates to a plate for circularly polarizing light, a ½ wave plate and a reflection-type liquid crystal display device utilizing said retardation plate. More specifically, the invention relates to a retardation plate and a fabrication method thereof, and a plate for circularly polarizing light, a ½ wave plate and a reflection-type liquid crystal display device utilizing said retardation plate which can be used in display devices of personal computers, AV devices, portable information communication devices, game and simulation devices, and a navigation system for cars and the like.
2. Description of the Related Art
A ¼ wave plate whose retardation (Re) is ¼ of a wavelength has a variety of uses. For example, it may be used in a reflection-type liquid crystal display device, in a pickup for an optical disk, in a glare proof film and the like. A ½ wave plate whose Re is ½ of the wavelength also has a variety of uses. These include use in a liquid crystal projector and the like. In order for the ¼ wave plate and the ½ wave plate to be used for a variety of purposes, it is desired that the ½ wave plate and the ¼ wave plate can sufficiently carry out their respective functions for incident light within the entire visible light region. Examples of a broad band retardation plate which can function sufficiently for incident light within the entire visible light region include those disclosed in Japanese Patent Application Laid-Open No. 5-27118, JP-A Nos. 5-100114, 10-68816, 10-90521, in which two sheets of polymer films having anisotropies different from each other are laminated.
However, in order to fabricate a conventional laminated type retardation plate, it is necessary to form two kinds of chips in which stretched double refraction films are cut in a direction having different angles from each other with respect to the direction of stretching, and to adhere these chips with an adhesive agent and laminate them. Further, adhering the two sheets of chips results not only in the increased costs of coating an adhesive material onto the chips, and chipping and adhering them, but also results in reduced performance due to angle shifts and the like when the chips are adhered. These effects on the performance cannot be ignored. Moreover, in a laminated type retardation plate formed by adhesion of the chips, there may be a problem of reduced performance due to increased thickness.
SUMMARY OF THE INVENTION
The present invention has been carried out in consideration of the foregoing problems, and an object of the present invention is to provide a reflection-type liquid crystal display device with improved display luminosity by utilizing a broad band retardation plate capable of being manufactured by a simple method and uniformly retarding incident light in the entire visible light region, specifically a broad band &lgr;/2 plate and a broad band plate for circularly polarizing light and the retardation plate. Moreover, another object of the present invention is to provide a method of fabricating a retardation plate in which a broad band retardation plate giving a uniform retardation to all of the incident lights can be fabricated by a simple process.
The present invention includes a retardation plate comprising a material including a positive intrinsic double refraction value and a material including a negative intrinsic double refraction value, with the materials resulting in retardation for wavelengths of electromagnetic radiation for the plate, and for wavelengths of 450 nm, 550 nm, and 650 nm, the plate retardation value for wavelengths of 450 nm is less than the plate retardation value for wavelengths of 550 nm, and the plate retardation value for wavelengths of 550 nm, is less than the plate retardation value for wavelengths of 650 nm.
The present invention also includes a retardation plate comprising a first layer which comprises a material including a positive intrinsic double refraction value and a second layer which comprises a material including a negative intrinsic double refraction value, wherein said first layer and said second layer each include lag axes, and are laminated to one another such that lag axes of said first layer and said second layer are substantially orthogonally crossed.
The present invention also includes a retardation plate, comprising a first layer which comprises a material including a positive intrinsic double refraction value and a second layer which comprises a material including a negative intrinsic double refraction value, wherein said first layer and said second layer each include molecular chains comprising an alignment direction substantially the same in both the first layer and the second layer.
The present invention also includes a ½ wave plate comprising a polarizing plate and a retardation plate laminated to the polarizing plate, the retardation plate comprising a material including a positive intrinsic double refraction value and a material including a negative intrinsic double refraction value, said retardation plate including retardation values for wavelengths of &lgr;, defined as Re(&lgr;), and for each of &lgr;=450 nm, &lgr;=550 nm and Re(&lgr;=450)<Re(&lgr;=550)<Re(&lgr;=650), 0.4≦Re(&lgr;)/&lgr;≦0.6, the polarizing plate including a polarizing plate transmission axis and said retardation plate including a lag axis, with said lag and transmission axis crossing each other.
The present invention also includes a ½ wave plate comprising a polarizing plate and a retardation plate laminated to the polarizing plate, the retardation plate including a first layer comprising a material including a positive intrinsic double refraction value, and a second layer comprising a material including a negative intrinsic double refraction value, said first layer and said second layer comprising double refraction, each layer including a lag axis with the layers laminated to one another with the lag axis of one layer substantially orthogonal to the lag axis of the other layer, said retardation plate comprising retardation values for wavelengths of &lgr;, defined as Re(&lgr;), and for each of &lgr;=450 nm, 550 nm and 650 nm, 0.4≦Re(&lgr;)/&lgr;≦0.6, and the polarizing plate including a polarizing plate transmission axis and said retardation plate including a lag axis with said lag axis and transmission axis crossing each other.
The present invention also includes a plate for circularly polarizing light, comprising a polarizing plate and a retardation plate laminated to the polarizing plate, the retardation plate comprising a material including a positive intrinsic double refraction value and a material including a negative intrinsic double refraction value, said retardation plate including retardation values for wavelengths of &lgr;, defined as Re(&lgr;), and for each of &lgr;=450 nm, &lgr;=550 nm and Re(&lgr;=450)<Re(&lgr;=550)<Re(&lgr;=650) 0.2≦Re(&lgr;)/&lgr;≦0.3, and the polarizing plate including a polarizing plate transmission axis and said retardation plate including a lag axis, with said lag and transmission axis crossing each other.
The present invention also includes a plate for circularly polarizing light, comprising a polarizing plate and a retardation plate laminated to the polarizing plate, the retardation plate comprising a first layer comprising a material including a positive intrinsic double refraction value and a second layer comprising a material including a negative intrinsic double refraction value, said first layer and said second layer comprising double refraction, each layer including a lag axis with the layers laminated to one another with the lag axis of one layer substantially orthogonal to the lag axis of the other layer, said retardation plate comprising retardation value for wavelengths of &lgr;, d
Chowdhury Tarifur R.
Duong Thoi V.
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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