GB2307767A - Back light unit in a liquid crystal display - Google Patents

Back light unit in a liquid crystal display Download PDF

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Publication number
GB2307767A
GB2307767A GB9624868A GB9624868A GB2307767A GB 2307767 A GB2307767 A GB 2307767A GB 9624868 A GB9624868 A GB 9624868A GB 9624868 A GB9624868 A GB 9624868A GB 2307767 A GB2307767 A GB 2307767A
Authority
GB
United Kingdom
Prior art keywords
light
crystal display
liquid crystal
display device
fluorescent lamp
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9624868A
Other versions
GB9624868D0 (en
Inventor
Seong-Kyu Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SK Hynix Inc
Original Assignee
Hyundai Electronics Industries Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hyundai Electronics Industries Co Ltd filed Critical Hyundai Electronics Industries Co Ltd
Publication of GB9624868D0 publication Critical patent/GB9624868D0/en
Publication of GB2307767A publication Critical patent/GB2307767A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133526—Lenses, e.g. microlenses or Fresnel lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0051—Diffusing sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/007—Incandescent lamp or gas discharge lamp
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133615—Edge-illuminating devices, i.e. illuminating from the side

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Liquid Crystal (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Planar Illumination Modules (AREA)

Description

2307767 LIQUID CRYSTAL DISPLAY DEVICE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally relates to a liquid crystal display device. More particularly, this invention relates to a back light structure capable of improving efficiency in the use of light.
Description of the Related Art
Various plane display devices such as a liquid crystal display(LCD), and a plasma display panel(PDP) have been widely and rapidly spread to substitute a cathod ray tube(CRT) having a large volume. Among these plane display devices, for the LCD device, there has been accomplished a remarkable improvement in a technology field in such areas as a display size, thickness, and picture quality so that the LCD has immediately substituted or is substituting the CRT display in applications such as camcorders, desktop computer, etc,. Of the L= devices available, an active matrix liquid crystal display device of combining liquid crystal technology with a semiconductor device one is conspicuous. This particular device has a memory performance added to an electrooptic effect of the liquid crystal by coupling each pixel of a matrix arrangement with active devices of thin film transistor having a non- linearity property.
1 1 The active matrix LCD device needs a light source added to a LCD panel since it does not have an illumination part compared with the CRT. A fluorescent lamp is now used for the light source of LCD device.
According to the equipped position of the fluorescent lamp, the light source is divided into a direct projection type and edgelight one. A back light unit of the direct projection type has a structure such that a light projected from the fluorescent lamp is homogenized by a diffusion plate, and then the homogenized light is incident upon the LCD panel. Meanwhile, a back light unit of the edge-light type has a structure such that a light projected from the fluorescent lamp is directly incident upon a LCD panel through a light-guiding plate.
The conventional one example for the edge-light type is provided in Fig. 1.
Referring to Fig. 1, a fluorescent lamp 1 is equipped in one edge portion of a light-guiding plate 3, and is surrounded by a lamp housing 2. The lamp housing 2 is equipped for the purpose of preventing the light of the fluorescent lamp 1 from escaping to a lateral side and of supporting the fluorescent lamp 1. A lightdiffusing plate 4 is equipped between the light-guiding plate 3 and a light -polarizing plate (not shown). The light -polarizing plate is established underneath LCD panel (not shown) which has a lower panel having thin film transistors and pixel coupled thereto, an upper panel having a color f ilter of red (R), green (G), and blue (B), a liquid crystal which is inserted between the lower panel and the 2 upper panel. A light reflecting plate 5 is equipped for the purpose of preventing the light of the fluorescent lamp 1 from escaping outside.
In a LCD module having the conventional back light unit, a picture is formed in such a manner that the light projected from the fluorescent lamp 1, through the light-diffusing plate 4 over the light-guiding plate 3, is incident upon the LCD panel. At this time, the loss of the light projected from the fluorescent lamp 1 is prevented by the light- reflecting plate 5 so that the light to be incident to the light-guiding plate 3 is uniformly scattered. Afterwards, the light is homogenized by the light-diffusing plate 4 and then is incident upon LCD panel through the light-polarizing plate.
However, since the conventional back light unit does not have an element 11or concentrating the homogenized light, the incident light to LCD panel is not concentrated. Thus, the conventional LCD module has a shortcoming that the light efficiency is very low.
SUMMARY OF THE INVENTION
Accordingly, it is an object to provide a liquid crystal display device capable of increasing efficiency in the use of light projected from a back light unit.
According to the present invention, a liquid crystal display device includes: a back light unit for projecting a light upon a 3 1 0 6 0 liquid crystal display panel having a plurality of pixel electrodes; and a plurality of condenser lenses inserted between the back light unit and the liquid crystal display panel, for concentrating the light projected from the back light unit to be incident upon each pixel of the liquid crystal display panel. The back light unit includes a light source, a lamp housing, and a light a light guiding plate.
BRIEF DESCRIPTION OF THE DRAWINGS
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiment of the present invention are clearly shown.
In the drawings:
FIG. 1 is a perspective view of a back light unit according to conventional art, FIG. 2 is a perspective view of a back light unit according to one embodiment of the present invention, and FIG. 3 is an exploded perspective view between the back light unit of FIG. 2 and a lower LCD panel.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 2, a fluorescent lamp 11 is surrounded by a 4 lamp housing 12. The lamp housing 12 is equipped for the purpose of preventing the light of the fluorescent lamp 1 from escaping to a lateral side and of supporting the fluorescent lamp 11. A lightdiffusing plate 14 is equipped between a light- guiding plate 13 and a light -polarizing plate (not shown) The light -polarizing plate is established underneath LCD panel(not shown). A lightreflecting plate 15 is equipped for the purpose of preventing the light of the fluorescent lamp 11 from escaping outside. A lightconcentrating plate 16 is equipped on the light-diffusing plate 14 and has a same arrangement to that of pixel electrodes.
In addition to the above, a cold cathode fluorescent lamp(CCFL) or halogen cathode fluorescent lamp(HCFL) can be selectively utilized as a light source.
FIG. 3 is an exploded perspective view between the back light unit of FIG. 2 and a lower LCD panel, and it shows that each condenser lens is arranged at an overlapping poistion corresponding to each pixel of LCD panel.
Referring to FIG. 3, after a light is projected from the fluorescent lamp 11, the light is scattered by the light-guiding plate 13. At this time, escape of the light to the outside is prevented. Thereafter, the light is diffused by the lightdiffusing plate 14 attached on the light-guiding plate 13. Afterwards, the diffused light is incident upon the lightconcentrating plate 16, and is then concentrated by each condenser lens 16-1, 16-2, 16-3... of the light-concentrating plate 16. The light concentrating plate 16 includes a plurality of condenser is lens 16-1 is arranged under a corresponding pixel electrode 18-1 so that light condensed by condenser lenses 16-1, 16-2, 16-3... is incident upon the corresponding pixel electrodes 18-1, 18-2, 18-3... in the lower panel 17 including a thin film transistor and the pixel electrode 18. As a result, amount of light to be incident to each pixel electrode 18-1, 18-2, 18-3... is largely increased compared with the conventional LCD device not having the lightconcentrating plate 16.
As described hereinbefore, the present invention increases largely amount of light to be incident to LCD panel,thereby enhancing a picture quality.
other features, advantages and embodiments of the invention disclosed herein will be readily apparent to those exercising ordinary skill after reading the foregoing disclosures. In this regard, while specific embodiments of the invention have been described in considerable detail, variations and modifications of these embodiments can be effected without departing from the spirit and scope of the invention as described and claimed.
6

Claims (8)

  1. WHAT IS CLAIMED IS:
    0 0 6 1. A liquid crystal display device comprising:
    a back light unit for projecting a light upon a liquid crystal display panel having a plurality of pixel electrodes; and light -concentrating means having a plurality of condenser lenses inserted between the back light unit and the liquid crystal display panel, for concentrating the light projected from the back light unit to be incident upon each pixel of the liquid crystal display panel.
  2. 2. The liquid crystal display device in accordance with claim 1, wherein said back light unit comprises:
    light source; lamp housing for surrounding the light source, thereby for preventing light of the light source from escaping outside.; and a light guiding plate for guiding the light projected from the light source.
  3. 3. The liquid crystal display device in accordance with claim 2, wherein said back light unit further comprises a light-diffusing plate for diffusing the light from the light-guiding plate.
  4. 4. The liauid crystal display device in accordance with claim 3, wherein said back light unit further comprises a light-reflecting plate for preventing the light from the light-diffusing plate from 7 escaping to the outside of the back light unit.
  5. 5. The liquid crystal display device in accordance with claim 2, wherein said light source is a fluorescent lamp.
  6. 6. The liquid crystal display device in accordance with claim 5, wherein said fluorescent lamp is a cold cathode fluorescent lamp.
  7. 7. The liquid crystal display device in accordance with claim 5, wherein said fluorescent lamp is a halogen cathode fluorescent lamp.
  8. 8. The liquid crystal display device in accordance with claim 1, wherein each condenser lens is arranged under a corresponding pixel electrode so that light condensed by the condenser lens is incident upon the corresponding pixel electrode.
    8
GB9624868A 1995-12-02 1996-11-29 Back light unit in a liquid crystal display Withdrawn GB2307767A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1019950046242A KR970048754A (en) 1995-12-02 1995-12-02 Liquid crystal display

Publications (2)

Publication Number Publication Date
GB9624868D0 GB9624868D0 (en) 1997-01-15
GB2307767A true GB2307767A (en) 1997-06-04

Family

ID=19437481

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9624868A Withdrawn GB2307767A (en) 1995-12-02 1996-11-29 Back light unit in a liquid crystal display

Country Status (4)

Country Link
JP (1) JPH1054987A (en)
KR (1) KR970048754A (en)
DE (1) DE19649918A1 (en)
GB (1) GB2307767A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1566685A2 (en) * 2004-02-23 2005-08-24 LG Electronics, Inc. Liquid crystal display device with backlight unit using microlens array and fabricating method of microlens array
US7283118B2 (en) * 2001-11-27 2007-10-16 Sharp Kabushiki Kaisha Back light unit and liquid crystal display apparatus

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4798448A (en) * 1988-02-16 1989-01-17 General Electric Company High efficiency illumination system for display devices
WO1994027181A1 (en) * 1993-05-11 1994-11-24 The Secretary Of State For Defence Spatial light modulators
US5396406A (en) * 1993-02-01 1995-03-07 Display Technology Industries Thin high efficiency illumination system for display devices

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4798448A (en) * 1988-02-16 1989-01-17 General Electric Company High efficiency illumination system for display devices
US5396406A (en) * 1993-02-01 1995-03-07 Display Technology Industries Thin high efficiency illumination system for display devices
WO1994027181A1 (en) * 1993-05-11 1994-11-24 The Secretary Of State For Defence Spatial light modulators

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7283118B2 (en) * 2001-11-27 2007-10-16 Sharp Kabushiki Kaisha Back light unit and liquid crystal display apparatus
US8031165B2 (en) 2001-11-27 2011-10-04 Sharp Kabushiki Kaisha Back light unit and liquid crystal display apparatus
EP1566685A2 (en) * 2004-02-23 2005-08-24 LG Electronics, Inc. Liquid crystal display device with backlight unit using microlens array and fabricating method of microlens array
EP1566685A3 (en) * 2004-02-23 2006-03-22 LG Electronics, Inc. Liquid crystal display device with backlight unit using microlens array and fabricating method of microlens array

Also Published As

Publication number Publication date
KR970048754A (en) 1997-07-29
JPH1054987A (en) 1998-02-24
DE19649918A1 (en) 1997-06-05
GB9624868D0 (en) 1997-01-15

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)