Patent ID: 6942411

Claim:
A telescopic ball-point pen, comprising: a tubular body comprising a connection portion; a mouth ring removably attached to a distal end of the body; a sliding axial tube received within the tubular body; a sheath and a head cap secured to a proximal end of the sliding axial tube, both of which are adapted to rotationally slide along the connection portion of the tubular body; a tank refill received within the sliding axial tube; and a ball-point pen refill removably received within the refill tank, the ball-point pen refill comprising a pen tip; wherein an interior surface of the tubular body defines a first internal thread and a corresponding exterior surface of the sliding axial tube defines a first external thread to together form a driver screw portion, which permits the sliding axial tube to move back and forth within the body; wherein an interior surface of the sliding axial tube defines a second internal thread and a corresponding exterior surface of the refill tank defines a second external thread to together form a follower screw portion, which permits the refill tank to move back and forth within the sliding axial tube; wherein a pitch of the follower screw portion is greater than the pitch of the driver screw portion so that the amount of front-and-back movement of the refill tank is greater than that of the sliding axial tube per rotation of the tubular body relative to the sheath; wherein when the sheath and the tubular body are rotated, they are moved away from each other or closer together and, at the same time, the pen tip of the ball-point pen refill within the refill tank is projected beyond or received within the mouth ring.