US4170951A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Skipped stitch detection system
Assignee: Singer Co
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Filing: 1978-12-14
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Granted: 1979-10-16
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Expires: 1998-12-14
Abstract
Abstract A skipped stitch detection system for a sewing machine is provided with a strain gage mounted on the slack thread regulator. The strain gage is connected in a Wheatstone bridge configuration. An amplified output from the Wheatstone bridge and timing signals from the sewing machine are provided to a microprocessor which analyzes the thread tension profile to detect the occurrence of a skipped stitch.
Inventors
- 👤 Leo Dobrjanskyj
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:13
CPC Classifications
D; D06; D06H; D06H1/00; D05; D05B; D05B51/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
189 words
In a sewing machine having a support for work fabric to be stitched, cyclically operating stitch forming instrumentalities including a thread carrying needle adapted for endwise reciprocation to penetrate the fabric, a supply of thread for said needle, and a thread handling system including a tension control system for the thread disposed intermediate said supply and said needle, a skipped stitch detection system comprising: sensing means disposed intermediate said tension control means and said needle and responsive to thread tension for supplying a tension signal, the instantaneous value of which corresponds to the thread tension at the sensing means position, the value of said tension signal having a first cyclic profile corresponding to a normal stitch and a second cyclic profile corresponding to a skipped stitch; timing means for providing timing signals at predetermined times relative to the operating cycle of said stitch forming instrumentalities; means responsive to said timing signals for defining examination windows for said tension signal; and means for examining said tension signal within said examination windows and responsive to values of said tension signal corresponding to said second cyclic profile for executing a control function.
Claim 2
Dependent Claim
189 words
In a sewing machine having a support for work fabric to be stitched, cyclically operating stitch forming instrumentalities including a thread carrying needle adapted for endwise reciprocation to penetrate the fabric, a supply of thread for said needle, and a thread handling system including a tension control system for the thread disposed intermediate said supply and said needle, a skipped stitch detection system comprising: sensing means disposed intermediate said tension control means and said needle and responsive to thread tension for supplying a tension signal, the instantaneous value of which corresponds to the thread tension at the sensing means position, the value of said tension signal having a first cyclic profile corresponding to a normal stitch and a second cyclic profile corresponding to a skipped stitch; timing means for providing timing signals at predetermined times relative to the operating cycle of said stitch forming instrumentalities; means responsive to said timing signals for defining examination windows for said tension signal; and means for examining said tension signal within said examination windows and responsive to values of said tension signal corresponding to said second cyclic profile for executing a control function.
Claim 3
Dependent Claim
57 words
A system according to claim 1 wherein said stitch forming instrumentalities include a thread take up lever disposed intermediate said tension control system and said needle; said sewing machine further includes a slack thread regulator disposed intermediate said tension control system and said take up lever; and said sensing means is mounted on said slack thread regulator.
Claim 4
Dependent Claim
14 words
The system according to claim 2 wherein said sensing means includes a strain gage.
Claim 5
Dependent Claim
19 words
The system according to claim 3 wherein said strain gage is connected as an arm of a Wheatstone bridge.
Claim 6
Dependent Claim
131 words
The system according to claim 1 wherein the needle bottom dead center position corresponds to 0° and 360° of a 360° operating cycle of the sewing machine stitch forming instrumentalities; the cyclic profile of the thread tension value for a normal stitch having a first peak within the range of 135° to 180° of the operating cycle and a second peak with the range of 180° to 360° of the operating cycle; the cyclic profile of the thread tension value for a skipped stitch having a single peak within the range of 180° and 360° of the operating cycle; and said examining means is responsive to the tension signal being below a predetermined threshold value within the range of 135° to 180° of the operating cycle for executing said control function.
Claim 7
Dependent Claim
42 words
The system according to claim 5 wherein the cyclic profiles of the thread tension values for normal and skipped stitches includes a region of low tension and said examining means utilizes the tension signal within said region to set a reference level.
Claim 8
Dependent Claim
38 words
The system according to claim 5 wherein said examining means is operative a plurality of times within the range of 135° to 180° of the operating cycle so as to compensate for shifts in the thread tension profile.
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) | 1982-10-15 | 1983-04-16 | 1983-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-10-15 | 1987-04-16 | 1987-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-10-15 | 1991-04-16 | 1991-10-16 | $7700.00 | Window Closed / Lapsed |