Hand tool having an adjustable head with a joint lock mechanism

1. A hand tool having an adjustable head with a joint lock mechanism comprising:

a head having a rear end with a convex pivotal portion;

a handle having a front end with a hollow cavity receiving said convex pivotal portion and pivotally coupled to the convex pivotal portion, the handle having a first aperture longitudinally extending from at the front end thereof, and a second aperture perpendicularly intersecting the first aperture; and

a fastening device disposed through the convex pivotal portion and the device is hollow cavity to be pivotally coupled to the convex pivotal portion while being fixedly coupled to the handle; and

the joint lock mechanism being disposed between the rear end of the head and the front end of the handle, the joint lock mechanism comprising:

a first engaging device disposed at the convex pivotal portion;

a push button received in the second aperture and formed with a through hole, the push button being provided with a first engaging portion disposed beneath the through hole, the first engaging portion having a front end and a rear end;

a second engaging device received in said first aperture, the second engaging device having a front end, a rear end, an engaging portion disposed at the front end thereof and a second engaging portion disposed between the front and the rear ends thereof; said second engaging device passing through the through hole of the push button;

a first elastic device received in the first aperture and abutting the rear end of the second engaging device such that the second engaging device is provided with a forward force to engage the engaging portion of the front end of the second engaging device with the first engaging device;

a second elastic device disposed at the bottom of the push button such that the push button is provided with an upward force to engage the first engaging portion of the push button with the second engaging portion of the second engaging device such that;

when the first engaging portion engages the second engaging portion, the front end of the first engaging portion abuts against the front end of the second engaging portion such that the second engaging device engages the first engaging device and is prevented from moving backwards along the first aperture and when the push button is pressed down, the front end of the second engaging portion disengages the front end of the first engaging portion; the head then being pivotally rotatable with respect to the handle, the first engaging device starts to disengage the second engaging device and pushes the second engaging device backwards along the first aperture with a tip of the first engaging device while still maintaining contact with the second engaging device, and the first engaging device re-engages the second engaging device after rotating at a predetermined angle.

2. The hand tool according to claim 1 , wherein the convex pivotal portion has a surface of arc shape.

3. The hand tool according to claim 1 , wherein the engaging portion of the second engaging device has a double tooth configuration.

4. The hand tool according to claim 1 , wherein the second elastic device comprises two second springs and each of the two second springs is received in a respective aperture formed at the bottom of the push button.

5. The hand tool according to claim 4 , wherein the second elastic device further comprises two hollow pins to hold the respective second springs and to guide and position the second springs to the respective apertures.

6. The hand tool according to claim 1 , wherein the front end of first engaging portion of the push button is formed with an inclined surface and the front end of the second engaging portion is formed with an inclined surface to match the front end of first engaging portion.

7. The hand tool according to claim 1 , wherein the first engaging device has a plurality of teeth formed equidistantly along the surface of the convex pivotal portion, and the engaging portion of the second engaging device 15 engages one of the plurality of teeth.

8. The hand tool according to claim 1 , wherein the first engaging device has a plurality of slots formed equidistantly along the surface of the convex pivotal portion, and the engaging portion of the second engaging device engages one of the plurality of slots.

9. The hand tool according to claim 1 , wherein the push button has a surface formed with an anti-slip pattern.

10. The hand tool according to claim 1 , wherein the push button has a surface formed with a pattern consisting of a word “LOCK”, a sideview mark of the head and a double arrow crossing the side-view mark.

11. The hand tool according to claim 1 , wherein the head further comprises a control knob to control the operating direction of the hand tool.

12. The hand tool according to claim 1 , wherein the first engaging device hits a plurality of teeth formed equidistantly along the surface of the convex pivotal portion, and the engaging portion of the second engaging device engages one of the plurality of teeth.

13. The hand tool according to claim 1 , wherein the first engaging device has a plurality of slots formed equidistantly along the surface of the convex pivotal portion, and the engaging portion of the second engaging device engages one of the plurality of slots.