US4565143A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of automatically adjusting thread tension in a sewing machine
Assignee: Janome Corp
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Filing: 1984-01-25
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Granted: 1986-01-21
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Expires: 2004-01-25
Abstract
Abstract A method of automatically adjusting thread tension in a sewing machine including detecting changes of load subjected on the needle bar caused when the needle penetrates the fabric to be sewn and adjusting the electric driving part of the thread tension device in accordance with the values of the changing components of the load.
Inventors
- 👤 Susumu Hanyu
- 👤 Kenji Kato
- 👤 Kazumasa Hara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:01
CPC Classifications
D; D05; D05B; D05B47/00; D05B47/04; D05B55/00; D05D; D05D2207/00; D05D2207/05
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
244 words
A method for automatically adjusting tension of a thread passing to a needle in a sewing machine having a drive motor operatively connected to a needle bar carrying a needle which is vertically reciprocated to penetrate a fabric to be sewn, thread tension means operated in ony way to increase tension of the thread and operated in the other way to decrease tension of the thread extended to said needle, and a microcomputer including a read only memory for storing a plurality of thread tension control data each being specific to fabrics of different thicknesses and different hardnesses, and a random access memory for temporarily storing variable load signals, the method comprising the steps of: (a) detecting changes of a load applied to said needle bar when the needle penetrates the fabric; (b) converting the detected changes of the load into a data representing a property of said fabric; (c) storing said fabric property-representing data in said random access memory; (d) reading out from said read only memory a new thread tension control data which corresponds to said fabric property representing data; and (e) comparing said read out new thread tension control data with a data representing a present value of tension applied to said thread and causing the thread tension means to be operated in said one or other way in dependence upon the value of said thread tension control data until said value of said new thread tension control data is reached.
Claim 2
Independent Claim
244 words
A method for automatically adjusting tension of a thread passing to a needle in a sewing machine having a drive motor operatively connected to a needle bar carrying a needle which is vertically reciprocated to penetrate a fabric to be sewn, thread tension means operated in ony way to increase tension of the thread and operated in the other way to decrease tension of the thread extended to said needle, and a microcomputer including a read only memory for storing a plurality of thread tension control data each being specific to fabrics of different thicknesses and different hardnesses, and a random access memory for temporarily storing variable load signals, the method comprising the steps of: (a) detecting changes of a load applied to said needle bar when the needle penetrates the fabric; (b) converting the detected changes of the load into a data representing a property of said fabric; (c) storing said fabric property-representing data in said random access memory; (d) reading out from said read only memory a new thread tension control data which corresponds to said fabric property representing data; and (e) comparing said read out new thread tension control data with a data representing a present value of tension applied to said thread and causing the thread tension means to be operated in said one or other way in dependence upon the value of said thread tension control data until said value of said new thread tension control data is reached.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 1, wherein current waves are caused when the needle penetrates the fabric to be sewn, said detecting step including detecting changing components of said current waves.
Claim 4
Dependent Claim
41 words
The method as defined in claim 1, wherein said detecting step includes detecting a differential signal between a designated rotation speed and an actual rotation speed of the drive motor, said differential signal being obtained when said needle penetrates said fabric.
Claim 5
Dependent Claim
28 words
The method as defined claim 1, wherein said detecting step includes detecting a strain which may be applied to the needle bar when the needle penetrates said fabric.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-20 | 1989-07-22 | 1990-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-20 | 1993-07-22 | 1994-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-20 | 1997-07-22 | 1998-01-21 | $7700.00 | Window Closed / Lapsed |