Patent ID: 7431528

Claim:
A telescopic handwriting pen comprising: a tubelike inner section including at its both ends front and rear inner threads; a first coupling assembly including a rod-shaped member having first and second annular grooves two first O-rings put on the first and the second grooves, an annular recess between the first and the second grooves filled with lubricating oil, and an outer threaded extension projected from its rear end threadedly secured to the front inner threads of the inner section; a tubelike intermediate section including an inwardly extending rim at its rear end; a hollow cylindrical second coupling assembly including a rod-shaped member having third and fourth annular grooves two second O-rings put on the third and the fourth grooves, an annular recess between the third and the fourth grooves filled with lubricating oil, and an outer extension projected from its rear and lockingly fitted in a front end of the intermediate section; a cap including an outer threaded extension projected from its front end and threadedly secured to the rear inner threads of the inner section; a tubelike outer section including an inwardly extending rim at its rear end; and a writing head lockingly fitted in a front end of the outer section, whereby sliding the inner section rearward by holding the cap until a shoulder between the rear groove of the first coupling assembly and the threaded extension of the first coupling assembly is stopped by the inwardly extending rim of the intermediate section, and further sliding the inner section rearward until a shoulder between the rear groove of the second coupling assembly and the outer extension of the second coupling assembly is stopped by the inwardly extending rim of the outer section will fully extend the handwriting pen.