Red enhancement in white LED displays using UV-cured color conversion films

• US 10,472,520 B2
• Filed: 11/16/2016
• Issued: 11/12/2019
• Est. Priority Date: 11/16/2015
• Status: Active Grant

• Current Assignee: Moleculed Ltd.
• Original Assignee: StoreDot Ltd.
• Inventors: Szwarcman, Daniel, Cohen, Elad, Armon, Mor Shmuel, Kuks, Evgenia Liel (Jeny), Schwarz, Rony, Eisurovich, Elena, Aronov, Daniel, Sella, Eran
• Primary Examiner(s): Kosack, Joseph R
• Application Number:
  US15/353,373
• Publication Number:
  US 20170137628A1
• Time in Patent Office: 1,091 Days
• CPC Class Codes: C08F 120/14 Methyl esters , e.g. methyl (meth)acrylate
• CPC Class Codes: C08F 2810/20 leading to a crosslinking, either explicitly or inherently
• CPC Class Codes: C08K 5/3437 condensed with carbocyclic rings
• CPC Class Codes: C08K 5/5477 containing nitrogen in a heterocyclic ring
• CPC Class Codes: C09B 11/24 Phthaleins containing amino groups ; Phthalanes; Fluoranes; Phthalides; Rhodamine dyes; Phthaleins having heterocyclic aryl rings; Lactone or lactame forms of triarylmethane dyes
• CPC Class Codes: C09B 69/008 Dyes containing a substituent, which contains a silicium atom
• CPC Class Codes: C09B 69/103 containing a diaryl- or triarylmethane dye
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-condensed systems
• CPC Class Codes: C09K 2211/1048 with oxygen
• CPC Class Codes: G02F 1/133516 Methods for their manufacture, e.g. printing, electro-deposition or photolithography
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: G03F 7/0007 Filters, e.g. additive colour filters; Components for display devices
• CPC Class Codes: G03F 7/027 Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds G03F7/075 takes precedence
• CPC Class Codes: G03F 7/031 Organic compounds not covered by group G03F7/029
• CPC Class Codes: G03F 7/105 : having substances, e.g. indicators, for forming visible images
• CPC Class Codes: H10K 85/611 : Charge transfer complexes
• CPC Class Codes: H10K 85/657 : Polycyclic condensed heteroaromatic hydrocarbons

Abstract

Color conversion films for a LCD (liquid crystal display) having RGB (red, green, blue) color filters, as well as such displays, formulations, precursors and methods are provided, which improve display performances with respect to color gamut, energy efficiency, materials and costs. The color conversion films absorb backlight illumination and convert the energy to green and/or red emission at high efficiency, specified wavelength ranges and narrow emission peaks. For example, rhodamine-based fluorescent compounds are used in matrices produced by sol gel processes and/or UV (ultraviolet) curing processes which are configured to stabilize the compounds and extend their lifetime—to provide the required emission specifications of the color conversion films. Film integration and display configurations further enhance the display performance with color conversion films utilizing various color conversion elements.

Claims

1. A color conversion film for a LCD (liquid crystal display) having RGB (red, green, blue) color filters, the color conversion film comprising at least one rhodamine-based fluorescent (RBF) compound selected to absorb illumination from a backlight source of the LCD and have a R emission peak, wherein the backlight source of the LCD provides white illumination and the at least one RBF compound is red-fluorescent and defined by Formula 1:

2. The color conversion film of claim 1, produced at least partially by a UV (ultraviolet) curing process carried out using, to provide a matrix for the at least one RBF compound, a formulation comprising 65-70% monomers, 25-30% oligomers, and 5% photointiator.

3. The color conversion film of claim 2, wherein:

the monomers consist of at least one of;

dipropylene glycol diacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated (3) glyceryl acrylate and trimethylolpropane triacrylate,

the oligomers consist of at least one of;

polyester acrylate, modified polyester resin diluted with dipropyleneglycol diacrylate and aliphatic urethane hexaacrylate, and

the photointiator consists of at least one of;

alpha-hydroxy-cyclohexyl-phenyl-ketone and alpha-hydroxy ketone.

4. The color conversion film of claim 2, wherein 0.005-0.05% of the at least one RBF compound is added to the formulation.

5. The color conversion film of claim 1, further configured to shift some of a yellow region in the white illumination into a R transmission region of the R color filter.

6. An LCD comprising the color conversion film of claim 1.

7. The LCD of claim 6, wherein the color conversion film is in an LCD panel.