Sewing machine equipped with needle threading device

1. A sewing machine equipped with a needle threading device, comprising:

a needle bar supporting frame body on which there is mounted a needle bar that is mounted with a needle having a needle hole;

a needle threading shaft that is disposed on the needle bar supporting frame body and is supported vertically movably and also turnably in a peripheral direction;

a thread pressing part and a thread holding tool that are provided at a lower end of the needle threading shaft and that hold in a tensioned state a thread opposite the needle hole; and

a needle threading tool that is provided at a lower end of the needle threading shaft and that has a hook which reciprocates through the needle hole to pass the thread through the needle hole,

wherein the thread holding tool comprises:

a thread holding surface part that guides and holds the thread;

a thread pressing member that presses and sandwiches together with the thread holding surface part the thread;

a thread detachment preventing part, the thread being sandwhiched between the thread pressing member and the thread holding surface part; and

a thread holding plate that holds the thread which is fixed to the needle threading,shaft, and

wherein the, thread pressing member comprises a spring plate part that comprises a projection piece for preventing a thread detachment.

2. The sewing machine equipped with a needle threading device acorrding to claim 1 , wherein the thread holding tool further comprises a thread holding base member equipped with the thread holding plate, and the thread pressing member that is mounted on the thread holding base member and that holds the thread by pressing, and

wherein the thread holding plate forms a holding groove part that has an end surface of a groove, of which one end is opened, as a thread holding surface part which holds the thread,

wherein the spring plate part sandwiches together with the thread holding surface part the thread by pressing, and

wherein the projection piece is provided to cross the thread that is held by pressing by the holding groove part of the thread holding plate.

3. The sewing machine equipped with a needle threading device according to claim 2 , wherein a front end of the projection piece is at the same position as a position of the thread holding surface part.

4. The sewing machine equipped with a needle threading device according to claim 2 , wherein a front end of the projection piece is at a lower position than a position of the thread holding surface part.

5. The sewing machine equipped with a needle threading device according to claim 2 , wherein a front end of the projection piece is at a higher position than a position of the thread holding surface part.

6. The sewing machine equipped with a needle threading device according to claim 2 , wherein a rising piece is formed on at least one end in a width direction of a pressing plate part of the thread pressing member.

7. The sewing machine equipped with a needle threading device according to claim 2 , wherein a bottom part of a pressing plate part of the thread pressing member is formed in an arc shape.

8. The sewing machine equipped with a needle threading device according to claim 1 , wherein a rising piece is formed on at least one end in a width direction of a pressing plate part of the thread pressing member.

9. The sewing machine equipped with a needle threading device according to claim 1 , wherein a bottom part of a pressing plate part of the thread pressing member is formed in an arc shape.

10. A sewing machine equipped with a needle threading device, comprising:

a needle bar supporting frame body on which there is mounted a needle bar that is mounted with a needle having a needle hole;

a needle threading shaft that is disposed on the needle bar supporting frame body and is supported vertically movably and also turnably in a peripheral direction;

a thread pressing part and a thread holding tool that are provided at a lower end of the needle threading shaft and that hold in a tensioned state a thread opposite the needle hole; and

a needle threading tool that is provided at a lower end of the needle threading shaft and that has a hook which reciprocates through the needle hole to pass the thread through the needle hole,

wherein the thread holding tool comprises a thread holding surface part that guides and holds the thread, a thread pressing member that presses and sandwhiches together with the thread holding surface part the thread, and a thread detachment preventing part, the thread being sandwhiched between the thread pressing member and the thread holding surface part,

wherein, when passing the thread through the needle hole, the thread detachment preventing part regulates the thread so that the thread, which is sandwiched between the thread holding surface part and the thread pressing member of the thread holding tool, passes in a predetermined direction without deviating from a thread holding state,

wherein the thread holding tool further comprises a thread holding base member equipped with a thread holding plate that holds the thread which is fixed to the needle threading shaft, and the thread pressing member that is mounted on the thread holding base member and that holds the thread by pressing,

wherein the thread holding plate forms a holding groove part has an end surface of a groove, of which one end is opend, as a thread holding surface part which holds the thread,

wherein the thread pressing member comprises a spring plate part that sandwhiches together with the thread holding surface part the thread by pressing , and also comprises a projection piece for preventing thread detachment, and

wherein the projection piece is provided to cross the thread that is held by pressing by the holding groove part of the thread holding plate.

11. The sewing machine equipped with a needle threading device according to claim 10 , wherein a rising piece is formed on at least one end in a width direction of a pressing plate part of the thread pressing member.

12. The sewing machine equipped with a needle threading device according to claim 10 , wherein a front end of the projection piece is at a lower position than a position of the thread holding surface part.