Color cathode ray tube with selective light absorption film

• US 5,315,209 A
• Filed: 03/05/1993
• Issued: 05/24/1994
• Est. Priority Date: 09/27/1990
• Status: Expired due to Term

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Iwasaki, Yasuo
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Patel, Ashok
• Application Number:
  US08/042,908
• Time in Patent Office: 445 Days
• Field of Search: 313/474, 313/478, 313/479, 313/467, 313/468, 313/112, 313/313, 313/466, 313/477 R, 313/480, 358/252, 358/253, 358/250, 358/311, 359/601
• US Class Current: 313/478
• CPC Class Codes: C09K 11/584 with zinc or cadmium
• CPC Class Codes: C09K 11/642 with zinc or cadmium
• CPC Class Codes: C09K 11/7789 Oxysulfides
• CPC Class Codes: H01J 29/185 measures against halo-phenomena
• CPC Class Codes: H01J 29/187 screens with more than one luminescent material (as mixtures for the treatment of the screens) for several superimposed luminescent layers H01J29/26; for adjacent dots or lines of different luminescent material H01J29/32
• CPC Class Codes: H01J 29/28 with protective, conductive or reflective layers
• CPC Class Codes: H01J 29/898 Spectral filters

Abstract

A color cathode ray tube includes a face plate, and a selective light absorption film formed on the external surface of the face plate to improve the emission tint, the film having a predetermined characteristic of spectral transmittance. The selective light absorption film is formed of a coating material which consists of a base coating including an alcoholic solution of silicon alkoxide having --OH group or --OR group, and an organic or inorganic dye or pigment mixed into the base coating. Such a coating material is applied onto the external surface of the face plate to form the selective light absorption film. The selective light absorption film has main and auxiliary absorbing bands. If the fluorescent face of the face plate includes a blue fluorescent element of ZnS:Ag, a green fluorescent element of ZnS:Au, Cu and Al and a red fluorescent element of Y₂ O₂ S:Eu, the selection is made that the absorption peak of the main absorbing band has a wavelength equal to 580 nm and the absorption peak of the auxiliary absorbing band has a wavelength equal to 660 nm.

Claims

1. A color cathode ray tube comprising:

a face plate including,

a blue fluorescent element of a sulfide family disposed on an inner surface for emitting a blue-colored light when an electron beam impinges the blue fluorescent element,

a green fluorescent element of a sulfide family disposed on an inner surface for emitting a green-colored light when an electron beam impinges the green fluorescent element, and

a red fluorescent element of a rare earth metals family disposed on an inner surface for emitting a red-colored light with an emission spectrum thereof being linear when an electron beam impinges the red fluorescent element; and

a selective light absorption film formed on an external surface of said face plate by applying a selective light absorption liquid onto said external surface;

said liquid consisting of a transparent base coating formed of a material from a silica family and a colored compound mixed into said base coating;

said selective light absorption film having optical characteristics including a main absorbing band and an auxiliary absorbing band, an absorption peak of said main absorbing band being in a first wavelength region between a main spectral wavelength of the emitted green-colored light and a main spectral wavelength of the emitted red-colored light, and an absorption peak of said auxiliary absorbing band being in a second wavelength region having wavelengths, said wavelengths of said second wavelength region being longer than that of a main spectral wavelength of the emitted red-colored light.

2. The color cathode ray tube as defined in claim 1 wherein the absorption peak of said main absorbing band is in a range between 570 nm and 610 nm and the absorption peak of said auxiliary absorbing band is in a range between 640 nm and 690 nm.

3. The color cathode ray tube as defined in claim 1 wherein said blue fluorescent element is formed on ZnS:

Ag, said green fluorescent element is formed of ZnS;

Au, Cu and Al, and said red fluorescent element is formed of Y₂ O₂ S;

Eu.

4. The color cathode ray tube as defined in claim 3 wherein the absorption peak of said main absorbing band has a wavelength equal to 580 nm and the absorption peak of said auxiliary absorbing band has a wavelength equal to 660 nm.

5. The color cathode ray tube as defined in claim 1, further comprising:

an electrically conductive member for grounding said selective light absorption film;

said selective light absorption film being electrically conductive, whereby charges on said selective light absorption film can be discharged to ground through said conductive member.

6. The color cathode ray tube as defined in claim 1 wherein said transparent base coating is an alcoholic solution of silicon alkoxide having an --OH group.

7. The color cathode ray tube as defined in claim 1 wherein said transparent base coating is an alcoholic solution of silicon alkoxide having an --OR group.