Illumination unit and liquid crystal display device using the unit

• US 7,210,841 B2
• Filed: 12/25/2002
• Issued: 05/01/2007
• Est. Priority Date: 12/25/2001
• Status: Expired due to Fees

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Inventors: Amaya, Toshio
• Primary Examiner(s): Luebke; Renee
• Assistant Examiner(s): Lee; Gunyoung T.
• Application Number:
  US10/500,123
• Publication Number:
  US 20050018416A1
• Time in Patent Office: 1,588 Days
• Field of Search: 362632- 4, 362/560, 362/561, 362/580, 349/58, 349/62, 349/65, 349/60
• US Class Current: 362/632
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0093 Means for protecting the light guide
• CPC Class Codes: G02F 1/133311 Environmental protection, e.g. against dust or humidity
• CPC Class Codes: G02F 1/133385 with cooling means, e.g. fans
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133628 with cooling means

Abstract

The liquid crystal display device is provided with: light sources; light guiding plate for guiding light from the light sources to a direction of a liquid crystal panel; reflection sheet to cover the light guiding plate and light sources; frame portion for supporting the light guiding plate and light sources, both of which are covered with the reflection sheet (lighting element), from the upper side of the lighting element; rear face cover for housing the lighting element and fitted with the frame portion; and shield portion disposed between the rear face cover and lighting element. The shield portion is made from high heat conductivity material and shields gaps between the frame portion and rear face cover, gaps between the rear face cover and lighting element, and a plurality of heat discharge holes formed on the bottom of the rear face cover to isolate the display area from the gaps.

Claims

1. A lighting unit comprising:

a lighting element provided with, a light guiding plate having a light emission face, facets and a rear face, a light source provided at one of the facets and a reflector covering the rear face and the facets of the light guiding plate and the light source,

wherein light emitted from the light source is guided into the light guiding plate and is emitted from the light emission face outside the lighting element;

a housing covering an edge portion of the light emission face, the facets and the rear face of the light guiding plate,

wherein heat discharge holes discharging heat generated in the lighting unit to the outside of the lighting unit are formed in a region of the housing which is located so as to correspond to the rear face of the light guiding plate; and

a dust shield portion preventing airflow and

being provided between at least the rear face of the light guiding plate and the housing so as to cover the heat discharge holes.

2. The lighting unit according to claim 1, wherein

the housing comprises a frame portion which covers the edge portion of the light emission face and the facets of the light guiding plate, and

a rear face supporting portion which covers the rear face of the light guiding plate and a lower end portion of the frame portion.

3. The lighting unit according to claim 2, wherein the shield portion is tabular and is positioned in such a fashion that an outer periphery thereof is between an inner periphery and an outer periphery of each of the frame portion.

4. The lighting unit according to claim 2, wherein the shield portion has the shape of a box and is positioned in such a fashion that an outer periphery thereof is between an inner periphery and an outer periphery of each of the frame portion.

5. The lighting unit according to claim 1, wherein the shield portion is made from a material having heat conductivity higher than that of the air.

6. A liquid crystal display device comprising:

the lighting unit according to claim 5, and

a liquid crystal panel disposed on the light emission face of the lighting unit.

7. A liquid crystal display device comprising:

the lighting unit according to claim 1; and

a liquid crystal panel disposed on the light emission face side of the lighting unit.