US5434430A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Drop size detect circuit
Assignee: HP Inc
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Filing: 1993-04-30
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Granted: 1995-07-18
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Expires: 2013-04-30
Abstract
Abstract An optical drop detect circuit for a thermal ink jet printer. The optical drop detect circuit includes an optical sensor for providing an electrical output indicative of a presence of an ink drop, a transconductance amplifier responsive to the output of said optical sensor, first and second cascaded bandpass amplifiers responsive to the transconductance amplifier, a first comparator circuit responsive to the output of the cascaded bandpass amplifiers for providing an output pursuant to optical sensing of a first minimum ink drop size, and a second comparator circuit responsive to the output of the cascaded bandpass amplifiers for providing an output pursuant to optical sensing of a second minimum ink drop size.
Inventors
- 👤 Lowell Stewart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:10
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/07; B41J2/125; B41J2/115; B41J2/135; B41J2/165; B41J2/16579
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
167 words
An optical drop detect circuit comprising: an optical sensor for providing an output indicative of a presence of an ink drop in a light beam sensed by the optical sensor; amplifier means responsive to the output of said optical sensor for providing an amplified output; bandpass amplifier means responsive to said amplified output for providing a bandpass output; first comparator means responsive to said bandpass output for providing a first comparator output that is indicative of when said bandpass output decreases below a first predetermined threshold, said first comparator output being indicative of sensing of an ink drop having a size at least as large as a first minimum drop size; and second comparator means for providing a second comparator output indicative of when said bandpass output decreases below a second predetermined threshold, said second comparator output being indicative of sensing of an ink drop having a size at least as large as a second minimum drop size which is different from said first minimum drop size.
Claim 2
Dependent Claim
167 words
An optical drop detect circuit comprising: an optical sensor for providing an output indicative of a presence of an ink drop in a light beam sensed by the optical sensor; amplifier means responsive to the output of said optical sensor for providing an amplified output; bandpass amplifier means responsive to said amplified output for providing a bandpass output; first comparator means responsive to said bandpass output for providing a first comparator output that is indicative of when said bandpass output decreases below a first predetermined threshold, said first comparator output being indicative of sensing of an ink drop having a size at least as large as a first minimum drop size; and second comparator means for providing a second comparator output indicative of when said bandpass output decreases below a second predetermined threshold, said second comparator output being indicative of sensing of an ink drop having a size at least as large as a second minimum drop size which is different from said first minimum drop size.
Claim 3
Dependent Claim
55 words
The optical detect circuit of claim 1 wherein said bandpass amplifier means includes a passband that is matched to the frequency spectrum of the output provided by said optical sensor for a particular range of ink drop sizes, a range of drop velocities, and an average shape of the beam sensed by said optical sensor.
Claim 4
Dependent Claim
18 words
The optical detect circuit of claim 2 wherein said bandpass amplifier means includes first and second bandpass amplifiers.
Claim 5
Dependent Claim
17 words
The optical detect circuit of claim 3 wherein said first and second bandpass amplifiers have identical passbands.
Claim 6
Dependent Claim
27 words
The optical detect circuit of claim 1 wherein said first and second thresholds comprise first and second percentages of a steady state average of said bandpass output.
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) | 1998-07-17 | 1999-01-16 | 1999-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-17 | 2003-01-16 | 2003-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-17 | 2007-01-16 | 2007-07-18 | $7700.00 | Window Closed / Lapsed |