Writing instrument with movable closure

Claim 1

In a writing instrument with a movable closure fabricated to repeat the operation of operatively rotating a rear holder barrel (2) to actuate a cam sleeve (8) so that a writing section (19) of a writing unit is projected from an opening (1-1) in the holder barrel (1) into a writing operation and retracted and stored in an airtight condition within the barrel in a non-writing operation, said writing instrument with the movable closure including: a front holder barrel (1) with a tapered reduced diameter at its forward open-ended portion (1-1), an elastic snap member (3) including a cylinder (3-1) and a plurality of support segments (3-2) which extend from the cylinder and which are provided at one end thereof with inward covers (3-3), the snap member (3) being disposed on the inner surface of the front holder barrel (1) and being adapted to have its cylinder (3-1) loosely mounted over a first slider (4) having a forward positioned flange (4-2) for connection with the cylinder (3-1) and a rearwardly located pin (4-1), a cam sleeve (8) having cam grooves (8-1, 8-2), the cylinder (3-1) and the cam sleeve (8) being connected by a spring member (6) between the rear end of the former and the front end of the latter, the cam sleeve (8) having the front cam groove (8-1) for receiving the pin (4-1) of the slider (4), the writing unit (19) being disposed along the center axis of the holder barrel (1,2), its front end engaging a spring member (7), its rear end engaging a second slider (5), having a pin (5-1), the pin (5-1) being inserted in the cam groove (8-2), positioned at the rear of the cam sleeve, the pins (4-1) and (5-1) being arranged so that they are located in a slit (9-1) of a guide tube (9) fixed to the front holder barrel (1), whereby rotational operation of the rear holder barrel (2) in one direction causes the covers (3-3) to move into a closed position while rotation of the rear holder barrel in the opposite direction causes the covers (3-3) to be retracted causing a radial release of pressure on the support segments (3-2) causing the covers (3-3) to open simultaneously with the advance of the writing unit 19 to its projected position.