Data display CRT having a white-emitting screen

• US 4,377,768 A
• Filed: 06/11/1981
• Issued: 03/22/1983
• Est. Priority Date: 06/11/1981
• Status: Expired due to Term

• Current Assignee: Philips Electronicsnorth America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronicsnorth America Corporation (Koninklijke Philips N.V.)
• Inventors: Gallaro, Anthony V., Hedler, Robert A.
• Primary Examiner(s): Demeo, Palmer C.
• Assistant Examiner(s): O'Shea, Sandra L.
• Application Number:
  US06/272,608
• Time in Patent Office: 649 Days
• Field of Search: 313/467
• US Class Current: 313/467
• 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

Abstract

The invention provides an advantageous blend of green, orange and blue-emitting phosphors to constitute an improved white-emitting screen component in a data display CRT. The improved white-emitter evidences medium-long persistence and thereby provides flicker-free imagery when the tube is expeditiously employed in conjunction with field refresh rates of 20 to 40 Hz.

Claims

1. A monochrome data display cathode ray tube having means for forming and directing an electron beam to impinge a cathodoluminescent screen evidencing medium-long image persistence disposed in the viewing area, such being constituted of a bright white-emitting screen component substantially defined by C.I.E. color coordinates having an "x" value in the order of 0.275±

0.015 and a "y" value in the order of 0.295±

0.010 and exhibiting a nominal color temperature in the order of 10,600°

K. (+18 MPCD), at substantially 15 KV, 50 ua excitation, said white-emitting screen component being formed of a discrete blend of phosphors comprising;

a medium-long persistence green-emitting phosphor evidencing an excited hue substantially defined by C.I.E. color coordinates having an "x" value in the order of 0.210±

0.010 and a "y" value in the order of 0.700±

0.010;

a medium-long persistence orange-emitting phosphor evidencing an excited hue substantially defined by C.I.E. color coordinates having an "x" value in the order of 0.550±

0.010 and a "y" value in the order of 0.440±

0.010; and

a medium persistence blue-emitting phosphor exhibiting an excited hue substantially defined by C.I.E. color coordinates having an "x" value in the order of 0.145±

0.010 and a "y" value in the order of 0.060±

0.005.

2. The monochrome data display cathode ray tube according to claim 1 wherein said green-emitting phosphor evidences a persistence of at least 32 milliseconds, said orange-emitting phosphor a persistence of at least 35 milliseconds, and said blue-emitting phosphor having a persistence of less than 1 millisecond, and wherein said white-emitting blend a persistence of at least 28 milliseconds.

3. The monochrome data display cathode ray tube according to claim 1 wherein the white-emitting cathodoluminescent screen component is a blend of phosphors evidencing persistence characteristics capable of producing a substantially flicker-free image display at scanning refresh rates substantially within the range of 20 to 40 Hz.

4. The monochrome data display cathode ray tube according to claim 1 wherein said green-emitting phosphor is a zinc orthosilicate host co-activated with manganese and arsenic (Zn₂ SiO₄ :

Mn;

As).

5. The monochrome data display cathode ray tube according to claim 1 wherein said orange-emitting phosphor is a cadmium silicate host co-activated with manganese and arsenic (CdSiO₃ :

Mn;

As).

6. The monochrome data display cathode ray tube according to claim 1 wherein said blue-emitting phosphor is a zinc sulfide host activated with silver (ZnS:

Ag).

7. The monochrome data display cathode ray tube according to claim 1 wherein said blend of phosphors substantially comprises:

60±

2 weight percent of orange-emitting CdSiO₃ ;

Mn;

As, 25±

2 weight percent of green-emitting Zn₂ SiO₄ ;

Mn;

As and 15±

2 weight percent of blue-emitting ZnS;

Ag.

8. A medium-long persistence white emitting cathodoluminescent phosphor component for use in a data display CRT screen, said component being a blend of phosphors substantially comprising:

60±

2 weight percent of orange-emitting CdSiO₃ ;

Mn;

As;

25±

2 weight percent of green-emitting Zn₂ SiO₄ ;

Mn;

As; and

15±

2 weight percent of blue-emitting ZnS;

Ag.