US4758449A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making a phosphor layer
Assignee: Panasonic Holdings Corp
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Filing: 1987-02-19
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Granted: 1988-07-19
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Expires: 2007-02-19
Abstract
Abstract Making method for a phosphor layer of a small diameter cathode ray tube comprises application of a centrifugal force of above 100G in a direction parallel to the axis of a glass bulb toward its bottom panel to become a face plate, thereby forcedly making sedimentation of phosphor powder onto the inner surface of the bottom panel, and thus, by adoptation of the centrifugal force, a phosphor layer of very fine and dense configuration and uniform thickness is obtainable even using such small medium grain size of phosphor powder of under 4 μm.
Inventors
- 👤 Masamichi Kimura
- 👤 Mutsuo Masuda
- 👤 Masao Tokunaga
- 👤 Shigeya Ashizaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:52
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/20; H01J9/22; H01J9/221; H01J9/224
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
223 words
A method for providing a phosphor layer on the inner surface of a flat bottom panel of a flask-shaped glass bulb, comprising: (a) introducing a phosphor slurry containing phosphor powder of medium grain size of 4 μm or smaller, a small amount of water glass and a small amount of electrolytic substance into a flask-shaped glass bulb having a flat bottom panel with an inner surface and a longitudinal axis generally normal to said flat bottom panel, (b) thereafter, applying a centrifugal force in a direction parallel to said axis of said glass bulb toward said bottom panel, thereby to forcedly cause said glass bulb to rotate so that its said axis is displaced from vertical substantially towards horizontal and so as to cause sedimentation of said phosphor powder onto said inner surface of said bottom panel, (c) thereafter, holding said glass bulb stationary for 0.5-15 minutes in a position in which said bottom panel is horizontal and said axis of said glass bulb is vertical, (d) thereafter, exhausting from said bulb supernatant liquid remaining from said slurry, (e) thereafter, injecting a washing liquid into said glass bulb, thereby to wash out the glass bulb while retaining said phosphor layer sedimented onto said inner surface and (f) thereafter, drying said phosphor layer to form a layer of phosphor powder on said inner surface.
Claim 2
Independent Claim
223 words
A method for providing a phosphor layer on the inner surface of a flat bottom panel of a flask-shaped glass bulb, comprising: (a) introducing a phosphor slurry containing phosphor powder of medium grain size of 4 μm or smaller, a small amount of water glass and a small amount of electrolytic substance into a flask-shaped glass bulb having a flat bottom panel with an inner surface and a longitudinal axis generally normal to said flat bottom panel, (b) thereafter, applying a centrifugal force in a direction parallel to said axis of said glass bulb toward said bottom panel, thereby to forcedly cause said glass bulb to rotate so that its said axis is displaced from vertical substantially towards horizontal and so as to cause sedimentation of said phosphor powder onto said inner surface of said bottom panel, (c) thereafter, holding said glass bulb stationary for 0.5-15 minutes in a position in which said bottom panel is horizontal and said axis of said glass bulb is vertical, (d) thereafter, exhausting from said bulb supernatant liquid remaining from said slurry, (e) thereafter, injecting a washing liquid into said glass bulb, thereby to wash out the glass bulb while retaining said phosphor layer sedimented onto said inner surface and (f) thereafter, drying said phosphor layer to form a layer of phosphor powder on said inner surface.
Claim 3
Dependent Claim
33 words
The method for making a phosphor layer in accordance with claim 1, wherein said water glass is at least one selected from the group consisting of sodium water glass or potassium water glass.
Claim 4
Dependent Claim
20 words
The method for making a phosphor layer in accordance with claim 1, wherein said water glass is sodium water glass.
Claim 5
Dependent Claim
20 words
The method for making a phosphor layer in accordance with claim 1, wherein said water glass is potassium water glass.
Claim 6
Dependent Claim
21 words
The method for making a phosphor layer in accordance with claim 1, wherein said electrolytic substance is a weak electrolytic substance.
Claim 7
Dependent Claim
33 words
The method for making a phosphor layer in accordance with claim 1, wherein said electrolytic substance is at least one selected from the group consisting of barium acetate, barium nitrate and potassium sulphate.
Claim 8
Dependent Claim
19 words
The method for making a phosphor layer in accordance with claim 1, wherein said electrolytic substance is barium acetate.
Claim 9
Dependent Claim
29 words
The method for making a phosphor layer in accordance with claim 1, wherein said centrifugal force is between 100 and 2000 times the magnitude of the force of gravity.
Claim 10
Dependent Claim
20 words
The method for making a phosphor layer in accordance with claim 1, wherein said medium grain size is 1-4 μm.
Claim 11
Dependent Claim
25 words
The method for making a phosphor layer in accordance with claim 1, wherein said forced sedimentation by centrifugal force is carried out for 3-15 minutes.
Claim 12
Dependent Claim
33 words
The method for making a phosphor layer in accordance with claim 1, wherein said glass bulb is for a cathode ray tube having a face panel of about 3 inches of diagonal length.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-07-19 | 1992-01-18 | 1992-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-07-19 | 1996-01-18 | 1996-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-07-19 | 2000-01-18 | 2000-07-19 | $7700.00 | Window Closed / Lapsed |