Sewing machine with needle threading device

Details Sewing machine with needle threading device Sewing machine with needle threading device

2002-07-11

2004-06-01

Nerbun, Peter (Department: 3765)

Sewing

Special machines

Pattern controlled or programmed

C112S225000

Reexamination Certificate

active

06742466

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sewing machine, and more particularly relates to a sewing machine provided with a needle threading device, wherein a thread passed through the needle eye of needle by a threading hook at a lower threading position may be released without fail from the threading hook holding the thread during the ascending process of the threading hook to the upper initial position.
2. Description of the Related Art
The inventors of the subject matter of this application has invented a sewing machine provided with a needle threading device which may be exactly operated to easily and rapidly pass a thread through the needle eye of the needle of the sewing machine as disclosed in the Japanese patent application No. 2000-366,159.
The threading device of prior art is further required to have a threading hook which may exactly catch the thread to be passed through the needle eye. Further, the threading hook is required to release the thread in the process for moving up to the upper initial position after the hook is operated to catch the thread and pass the thread through the needle eye. In case the thread is not released from the threading hook, the thread will give a load to the driver for moving up the hook and give an adverse influence to the threading device and to the control device.
OBJECTS OF THE INVENTION
The invention has been provided to eliminate the defects and disadvantages of the prior art.
It is, therefore, a principal object of the invention to provide a sewing machine provided with a threading device which is smoothly and exactly operated to pass a thread through the eye of needle of the sewing machine.
It is another object of the invention to provide a threading device including a threading hook which is operated to move down from an upper initial position to a lower threading position where the hook is operated to exactly catch the thread and pass the thread trough the needle eye.
It is another object of the invention to provide a control means for controlling the movement of the threading hook for the purpose of releasing the thread from the hook during movement of the hook from the lower threading position to the upper initial position for the purpose of removing the load of thread which may otherwise applied to the hook and the related mechanism.
SUMMARY OF THE INVENTION
In short, the invention relates to a sewing machine provided with a threading device, the sewing machine comprising a needle having a needle eye and attached to the lower end of a vertically reciprocating needle bar, a threading shaft having a threading hook mounted to the lower end thereof, a control means for providing a descending process wherein the threading shaft is moved down from an upper initial position to a lower threading position where the threading hook is operated to catch a thread and pass the thread through the needle eye and an ascending process wherein the threading shaft is moved up from the lower threading position to the initial upper position, the ascending process including an initial process wherein the threading shaft is moved up a predetermined distance from the lower threading position to pull up the threaded thread, a second process wherein the threading shaft is moved down a predetermined distance after the initial process to have the threading hook release the threaded thread and a final process wherein the threading shaft is moved up to the upper initial position after the second process while the threaded thread is released from the threading hook.


REFERENCES:
patent: 6564731 (2003-05-01), Sano et al.
patent: 2002-113281 (2002-04-01), None

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