US3821553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual wavelength moisture gauge having automatic gain control
Assignee: Honeywell Measurex Corp
•
Filing: 1972-11-17
•
Granted: 1974-06-28
•
Expires: 1992-11-17
Abstract
Abstract A dual wavelength type moisture gauge having a fixed source of radiation and capable of measuring moisture on all grades of paper. A fixed source of radiation having at least two wavelengths, one of which is sensitive to absorbtion of water and another which is substantially less sensitive to absorbtion by water, is positioned on one side of a sheet of paper. A detector unit is positioned either to receive backscattered radiation or transmitted radiation. The detector unit includes optical filters for separating the two wavelengths of interest. Transducers convert the optical signals to corresponding electrical signals. Connected to the transducers is an automatic gain control amplifier that has an input portion which alternately samples the two signals. The samples are amplified and supplied to an output portion which is synchronized with the input sampling portion for separating the sampled and amplified signals. One of the output signals is fed back to the gain control of the amplifier such that the gain of the amplifier will vary inversely with the output of the amplifier.
Inventors
- 👤 J French
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:13
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314; G01N21/35; G01N21/3554; G01N21/3559
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
292 words
An apparatus for measuring the moisture associated with a sheet of paper comprising: a. a constant intensity radiation source that emits a first spectral band of radiation lying substantially outside of the absorption band of water and a second spectral band of radiation lying substantially within the absorption band of water; b. optical means for collecting said radiation from said source; c. optical means for separating said radiation into first and second channels each including one of said spectral bands of radiation; d. converter means for converting said first and second channels of optical radiation into corresponding first and second electrical signals; e. amplifier means for amplifying said first and second electrical signals said amplifier means including 1. input switching means for alternately connecting said first and second channels of electrical information to said amplifier means; 2. an amplifier connected to said input switching means and having an output; 3. variable attenuator means connected to said amplifier means for controlling said output; 4. output switching means connected to said output of said amplifier; 5. driver means connected to said input switching means and said output switching means for causing the synchronous switching thereof whereby said first and second electrical signals are alternately sampled and amplified to a constant level and separated into two separate channels; 6. first and second demodulator means connected to said output switching means such that said first amplified electrical signal supplied to said first demodulator means and said second amplified electrical signal is supplied to said second demodulator means; 7. phase locking means connected to said first and second demodulator means and responsive to the output of said amplifier for supplying to said demodulators to a signal having a predetermined phase relationship with the output of said amplifier.
Claim 2
Independent Claim
292 words
An apparatus for measuring the moisture associated with a sheet of paper comprising: a. a constant intensity radiation source that emits a first spectral band of radiation lying substantially outside of the absorption band of water and a second spectral band of radiation lying substantially within the absorption band of water; b. optical means for collecting said radiation from said source; c. optical means for separating said radiation into first and second channels each including one of said spectral bands of radiation; d. converter means for converting said first and second channels of optical radiation into corresponding first and second electrical signals; e. amplifier means for amplifying said first and second electrical signals said amplifier means including 1. input switching means for alternately connecting said first and second channels of electrical information to said amplifier means; 2. an amplifier connected to said input switching means and having an output; 3. variable attenuator means connected to said amplifier means for controlling said output; 4. output switching means connected to said output of said amplifier; 5. driver means connected to said input switching means and said output switching means for causing the synchronous switching thereof whereby said first and second electrical signals are alternately sampled and amplified to a constant level and separated into two separate channels; 6. first and second demodulator means connected to said output switching means such that said first amplified electrical signal supplied to said first demodulator means and said second amplified electrical signal is supplied to said second demodulator means; 7. phase locking means connected to said first and second demodulator means and responsive to the output of said amplifier for supplying to said demodulators to a signal having a predetermined phase relationship with the output of said amplifier.
Claim 3
Dependent Claim
12 words
an amplifier connected to said input switching means and having an output;
Claim 4
Dependent Claim
12 words
an amplifier connected to said input switching means and having an output;
Claim 5
Dependent Claim
11 words
an integrator circuit to which said error signal is supplied; and
Claim 6
Dependent Claim
11 words
an integrator circuit to which said error signal is supplied; and
Claim 7
Dependent Claim
76 words
The apparatus of claim 1 wherein said demodulator circuit comprises: a. a bridge circuit having input means connected thereacross, two capacitive legs, and two switching legs responsive to said phase locked signal for alternately charging said capacitive legs to the peak value of alternate phases of a signal supplied to same input means whereby charge representative of the peak to peak value of the amplified signal supplied to said demodulator is captured on said capacitive legs.
Claim 8
Dependent Claim
147 words
The apparatus of claim 1 wherein said demodulator circuit comprises: a. first and second capacitive legs having one terminal in common; b. first and second switching means having one terminal in common and an othEr terminal of each connected to said first and second capacitive legs such that a bridge network is formed; c. input means connected between said common capacitor terminal and said common switch terminal; d. output means connected to the common node between said switch means and capacitor means; e. and switch control means connected to said switches for turning on said switches such that said capacitors are alternately charged to the peak value of the signal impressed upon said input means whereby the output signals supplied from said bridge network is a substantially dc signal having a magnitude equal to the peak to peak voltage of a signal supplied to said input means.
Claim 9
Dependent Claim
44 words
means for varying the gain of said amplifier means in response to the output of said integrator so that the output signal of said amplifier means remains at a substantially constant level said integrator providing a substantially zero residual error while maintaining loop stability.
Claim 10
Dependent Claim
44 words
means for varying the gain of said amplifier means in response to the output of said integrator so that the output signal of said amplifier means remains at a substantially constant level said integrator providing a substantially zero residual error while maintaining loop stability.
Claim 11
Dependent Claim
12 words
variable attenuator means connected to said amplifier means for controlling said output;
Claim 12
Dependent Claim
12 words
variable attenuator means connected to said amplifier means for controlling said output;
Claim 13
Dependent Claim
10 words
output switching means connected to said output of said amplifier;
Claim 14
Dependent Claim
10 words
output switching means connected to said output of said amplifier;
Claim 15
Dependent Claim
67 words
The apparatus of claim 3 wherein said switching means are field effect transistors having source, drain, and gate electrodes; and said switch control means includes means connected between the gate and source of said field effect transistor and responsive to the output of said phase locking means for causing said transistor to conduct a certain predetermined portion of the cycle of said first and second electrical signals.
Claim 16
Independent Claim
134 words
An apparatus for measuring the moisture associated with a sheet of paper comprising: a. a constant intensity radiation source that emits a first spectral band of radiation lying substantially outside of the absorption band of water and a second spectral band of radiation lying substantially within the absorption band of water; b. optical means for collecting said radiation from said source; c. optical means for separating said radiation into first and second channels each including one of said spectral bands of radiation; d. converter means for converting said first and second channels of optical radiation into corresponding first and second electrical signals; e. amplifier means for amplifying said first and second electrical signals and for providing at least one substantially constant output signal related to one of said electrical signals said amplifier means including:
Claim 17
Independent Claim
134 words
An apparatus for measuring the moisture associated with a sheet of paper comprising: a. a constant intensity radiation source that emits a first spectral band of radiation lying substantially outside of the absorption band of water and a second spectral band of radiation lying substantially within the absorption band of water; b. optical means for collecting said radiation from said source; c. optical means for separating said radiation into first and second channels each including one of said spectral bands of radiation; d. converter means for converting said first and second channels of optical radiation into corresponding first and second electrical signals; e. amplifier means for amplifying said first and second electrical signals and for providing at least one substantially constant output signal related to one of said electrical signals said amplifier means including:
Claim 18
Dependent Claim
41 words
driver means connected to said input switching means and said output switching means for causing the synchronous switching thereof whereby said first and second electrical signals are alternately sampled and amplified to a constant level and separated into two separate channels;
Claim 19
Dependent Claim
41 words
driver means connected to said input switching means and said output switching means for causing the synchronous switching thereof whereby said first and second electrical signals are alternately sampled and amplified to a constant level and separated into two separate channels;
Claim 20
Dependent Claim
37 words
first and second demodulator means connected to said output switching means such that said first amplified electrical signal supplied to said first demodulator means and said second amplified electrical signal is supplied to said second demodulator means;
Claim 21
Dependent Claim
37 words
first and second demodulator means connected to said output switching means such that said first amplified electrical signal supplied to said first demodulator means and said second amplified electrical signal is supplied to said second demodulator means;
Claim 22
Dependent Claim
38 words
phase locking means connected to said first and second demodulator means and responsive to the output of said amplifier for supplying to said demodulators to a signal having a predetermined phase relationship with the output of said amplifier.
Claim 23
Dependent Claim
38 words
phase locking means connected to said first and second demodulator means and responsive to the output of said amplifier for supplying to said demodulators to a signal having a predetermined phase relationship with the output of said amplifier.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |