Patent US4940997A successfully refreshed from Google Patents.
US4940997A
Expired / Lapsed
US
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Out-of-ink sensing method
Assignee: HP Inc
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Filing: 1989-08-08
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Granted: 1990-07-10
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Expires: 2009-08-08
Abstract
Abstract In an ink-jet printer, a ball check-valve (32) is used over the ink outlet (28) of an ink bag (16) to interrupt the flow of ink and/or air to the ink bladder when the ink supply in the bag falls below a predetermined level (40). The specific gravity of the ball is less than the specific gravity of ink in the bag but greater than the specific gravity of air.
Inventors
- 👤 Mindy A. Hamlin
- 👤 George Kaplinsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:36
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/17; B41J2/175; B41J2/17566; B41J2002/17576
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
73 words
In an ink-jet printer having an ink bag, a bladder, a printhead, and a three-way valve which can selectively provide ink from the bag to the bladder, or from the bladder to the printhead, or cut off flow of ink in any direction, the improvement consisting of using a ball check-valve to terminate ink flow from the ink bag to the bladder when ink in the ink bag falls below a predetermined level.
Claim 2
Dependent Claim
73 words
In an ink-jet printer having an ink bag, a bladder, a printhead, and a three-way valve which can selectively provide ink from the bag to the bladder, or from the bladder to the printhead, or cut off flow of ink in any direction, the improvement consisting of using a ball check-valve to terminate ink flow from the ink bag to the bladder when ink in the ink bag falls below a predetermined level.
Claim 3
Dependent Claim
27 words
The improvement of claim 1 wherein the ball check-valve is contained in a perforated cage placed above an ink outlet in the bottom of the ink bag.
Claim 4
Dependent Claim
13 words
The improvement of claim 2 wherein the perforated cage is made of polyethylene.
Claim 5
Dependent Claim
32 words
The improvement of claim 1 wherein the ball of the check-valve has a specific gravity that is less than the specific gravity of ink but greater than the specific gravity of air.
Claim 6
Dependent Claim
20 words
The improvement of claim 1 wherein ink flow is terminated when the ink in the ink bag is near depletion.
Claim 7
Dependent Claim
15 words
The improvement of claim 1 wherein the ball of the check-valve is made of polypropylene.
Claim 8
Dependent Claim
15 words
The improvement of claim 1 wherein the ball of the check-valve is made of polyethylene.
Claim 9
Dependent Claim
91 words
In an ink-jet printer having an ink bag, a bladder, a dimpler to initiate negative pressure in the bladder, a sensor to determine ink quantity in the bladder, a printhead, and a three-way valve which can selectively provide ink from the bag to the bladder, or from the bladder to the printhead, or cut off flow of ink in any direction, the improvement consisting of using a ball check-valve to terminate ink flow from the ink bag to the bladder when ink in the ink bag falls below a predetermined level.
Claim 10
Dependent Claim
91 words
In an ink-jet printer having an ink bag, a bladder, a dimpler to initiate negative pressure in the bladder, a sensor to determine ink quantity in the bladder, a printhead, and a three-way valve which can selectively provide ink from the bag to the bladder, or from the bladder to the printhead, or cut off flow of ink in any direction, the improvement consisting of using a ball check-valve to terminate ink flow from the ink bag to the bladder when ink in the ink bag falls below a predetermined level.
Claim 11
Dependent Claim
27 words
The improvement of claim 8 wherein the ball check-valve is contained in a perforated cage placed above an ink outlet in the bottom of the ink bag.
Claim 12
Dependent Claim
20 words
The improvement of claim 8 wherein ink flow is terminated when the ink in the ink bag is near depletion.
Claim 13
Dependent Claim
32 words
The improvement of claim 8 wherein the ball of the check-valve has a specific gravity that is less than the specific gravity of ink but greater than the specific gravity of air.
Claim 14
Dependent Claim
15 words
The improvement of claim 8 wherein the ball of the check-valve is made of polypropylene.
Claim 15
Dependent Claim
15 words
The improvement of claim 8 wherein the ball of the check-valve is made of polyethylene.
Claim 16
Dependent Claim
13 words
The improvement of claim 8 wherein the perforated cage is made of polyethylene.
References Cited (Backward Citations)
US3699914A
Cited
US4814786A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-09 | 1994-01-08 | 1994-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-09 | 1998-01-08 | 1998-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-09 | 2002-01-08 | 2002-07-10 | $7700.00 | Window Closed / Lapsed |