US3753472A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light pressure operated microbalance system
Assignee: United States Department of the Air Force
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Filing: 1971-08-12
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Granted: 1973-08-21
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Expires: 1991-08-12
Abstract
Abstract A swinging undamped microbalance that measures time intervals of successive half periods of complete swings using an optical lever consisting of a light source aligned to reflect light from a mirror mounted upon the balance onto a light sensitive detector. The time intervals which are electronically processed determine an off-balance signal that drives a servo which restores the balance by applying light pressure to a mirrored surface of a counter weight. The restoring force is in relation to weight increases of the sample being weighed.
Inventors
- 👤 K Zinnow
- 👤 J Dybwad
- 👤 W Alexander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:50
CPC Classifications
G; G01; G01G; G01G23/00; G01G23/18; G01G23/36; Y; Y10; Y10S; Y10S177/00; Y10S177/06
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
234 words
A balance system for detecting sample weight changes comprising: a. a swinging beam including a sample attached to one extreme thereof and a mirrored surface counter weight attached to the opposite extreme; b. means for sensing the null level crossings of the swinging beam including, 1. a first source of light; 2. a light sensitive detector; 3. a mirror mounted on the swinging beam and aligned to reflect light from the first light source to the light sensitive detector when the swinging beam is in the null level position; c. means for measuring the time intervals between the null level crossings with the measuring means fed by the sensing means, a time interval difference between successive half periods being indicative of an off-balance state and the measuring means including, 1. a first zero crossing detector fed by the light sensitive detector; 2. a Schmidt trigger fed by the zero crossing detector; 3. an integrating circuit fed by the Schmidt trigger; 4. a filter fed by the integrating circuit; and 5. a recorder fed by the filter; d. means for applying a restoring force, including a second source of light directed at the mirrored surface counter weight as controlled by the time interval measuring means, to the counter weight to place the swinging balance in an on-balance state; and e. means for measuring the restoring force, the output thereof being indicative of sample weight changes.
Claim 2
Dependent Claim
234 words
A balance system for detecting sample weight changes comprising: a. a swinging beam including a sample attached to one extreme thereof and a mirrored surface counter weight attached to the opposite extreme; b. means for sensing the null level crossings of the swinging beam including, 1. a first source of light; 2. a light sensitive detector; 3. a mirror mounted on the swinging beam and aligned to reflect light from the first light source to the light sensitive detector when the swinging beam is in the null level position; c. means for measuring the time intervals between the null level crossings with the measuring means fed by the sensing means, a time interval difference between successive half periods being indicative of an off-balance state and the measuring means including, 1. a first zero crossing detector fed by the light sensitive detector; 2. a Schmidt trigger fed by the zero crossing detector; 3. an integrating circuit fed by the Schmidt trigger; 4. a filter fed by the integrating circuit; and 5. a recorder fed by the filter; d. means for applying a restoring force, including a second source of light directed at the mirrored surface counter weight as controlled by the time interval measuring means, to the counter weight to place the swinging balance in an on-balance state; and e. means for measuring the restoring force, the output thereof being indicative of sample weight changes.
Claim 3
Dependent Claim
4 words
a light sensitive detector;
Claim 4
Dependent Claim
4 words
a light sensitive detector;
Claim 5
Dependent Claim
9 words
a Schmidt trigger fed by the zero crossing detector;
Claim 6
Dependent Claim
9 words
a Schmidt trigger fed by the zero crossing detector;
Claim 7
Dependent Claim
37 words
A balance system for detecting sample weight changes according to claim 1 which further comprises means for applying a light push to the mirrored surface of the counter weight to maintain the motion of the swinging beam.
Claim 8
Dependent Claim
120 words
A balance system for detecting sample weight changes according to claim 1 wherein the means for applying a light push comprises: a. a second level zero crossing detector fed by the light sensitive detector; b. a second Schmidt trigger fed by the second level zero crossing detector; c. a monostable multivibrator fed by the second Schmidt trigger; d. a field effect transistor switch fed by the monostable multivibrator; e. a potentiometer controlled voltage source feeding the field effect transistor switch for controlling the output magnitude thereof; f. a motor having a shaft controlling the light push; and g. a cam switch connected to the shaft of the motor for regulating power from the field effect transistor switch to the motor.
Claim 9
Dependent Claim
8 words
an integrating circuit fed by the Schmidt trigger;
Claim 10
Dependent Claim
8 words
an integrating circuit fed by the Schmidt trigger;
Claim 11
Dependent Claim
72 words
a mirror mounted on the swinging beam and aligned to reflect light from the first light source to the light sensitive detector when the swinging beam is in the null level position; c. means for measuring the time intervals between the null level crossings with the measuring means fed by the sensing means, a time interval difference between successive half periods being indicative of an off-balance state and the measuring means including,
Claim 12
Dependent Claim
72 words
a mirror mounted on the swinging beam and aligned to reflect light from the first light source to the light sensitive detector when the swinging beam is in the null level position; c. means for measuring the time intervals between the null level crossings with the measuring means fed by the sensing means, a time interval difference between successive half periods being indicative of an off-balance state and the measuring means including,
Claim 13
Dependent Claim
8 words
a filter fed by the integrating circuit; and
Claim 14
Dependent Claim
8 words
a filter fed by the integrating circuit; and
Claim 15
Dependent Claim
21 words
A balance system for detecting sample weight changes according to claim 3 wherein the second light source is a laser beam.
Claim 16
Dependent Claim
64 words
a recorder fed by the filter; d. means for applying a restoring force, including a second source of light directed at the mirrored surface counter weight as controlled by the time interval measuring means, to the counter weight to place the swinging balance in an on-balance state; and e. means for measuring the restoring force, the output thereof being indicative of sample weight changes.
Claim 17
Dependent Claim
64 words
a recorder fed by the filter; d. means for applying a restoring force, including a second source of light directed at the mirrored surface counter weight as controlled by the time interval measuring means, to the counter weight to place the swinging balance in an on-balance state; and e. means for measuring the restoring force, the output thereof being indicative of sample weight changes.
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) | 1976-08-20 | 1977-02-19 | 1977-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-20 | 1981-02-19 | 1981-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-20 | 1985-02-19 | 1985-08-21 | $7700.00 | Window Closed / Lapsed |