Aluminate phosphor with a polyphosphate coating

• US 5,998,047 A
• Filed: 06/25/1998
• Issued: 12/07/1999
• Est. Priority Date: 06/28/1997
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Mayr, Walter, Rhonda, Cornelis, Nikol, Hans, Bechtel, Helmut, Justel, Thomas, Czarnojan, Wolfram
• Primary Examiner(s): NOLD, CHARLES R
• Application Number:
  US09/104,486
• Time in Patent Office: 530 Days
• Field of Search: 313/584, 313/585, 313/586, 313/587, 313/484, 313/485, 313/487, 313/486, 313/582, 428/690, 428/403, 428/407, 252/301.4 R, 252/301.6 P
• US Class Current: 428/690
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: H01J 2211/42 Fluorescent layers
• CPC Class Codes: H01J 29/185 measures against halo-phenomena
• CPC Class Codes: H01J 29/20 characterised by the luminescent material
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

A plasma display device with a phosphor screen, comprising a phosphor composition of an UV-phosphor furnished with a coating which includes one or more catena-polyphosphates of metals of the group formed by the alkaline earth metals, zinc, cadmium and manganese, can effectively be used to counteract degradation of the phosphor by UV-excitation.

Claims

1. A plasma display device with a phosphor screen comprising a phosphor composition of a UV aluminate phosphor provided with a coating comprising one or more catena-polyphosphates of metals selected from the group consisting of alkaline earth metals, zinc, cadmium and manganese.

2. A plasma display device with a phosphor screen as claimed in claim 1, characterized in that catena-polyphosphates have a chain length of 3 to 90.

3. A plasma display device with a phosphor screen as claimed in claim 1, characterized in that the coating comprises a catena-polyphosphate of an alkaline earth metal and 0.1 to 20% by weight of the coating of a catena-polyphosphate of a metal selected from the group consisting of zinc, cadmium, and manganese.

4. A plasma display device with a phosphor screen as claimed in claim 3, characterized in that the alkaline earth metal is at least a metal selected from the group consisting of calcium, strontium and barium, and the coating comprises 5% by weight of the coating of zinc-catena-polyphosphate and/or 5% by weight of manganese-catena-polyphosphate.

5. A plasma display device with a phosphor screen as claimed in claim 1, characterized in that the phosphor composition comprises a covering layer of a dispersion aid on said coating.

6. A plasma display device with a phosphor screen as claimed in claim 1, characterized in that the phosphor composition comprises a covering layer with a pigment on said coating.

7. A plasma display device with a phosphor screen as claimed in claim 1, characterized in that the UV-phosphor is composed of Ba(Al,Mg)₁₁ O₁₉ :

Eu²⁺.

8. A phosphor composition of UV aluminate-phosphor provided with a coating comprising one or more catena-polyphosphates of metals selected from the group consisting of alkaline earth metals, zinc, cadmium and manganese.