| 摘要 |
PROBLEM TO BE SOLVED: To prevent a pen point part from projecting through the tip opening part of a shaft tube even under the degree of the slight touching with a knock body by a method wherein the operating load of the knock body is set to a specified value. SOLUTION: A refill 5 is inserted in a shaft tube 2 in the fashion that the stand-by distance H from the tip opening part 2a of the shaft tube to the tip of a penpoint part 4 under the condition that the pen point part 4 is housed in the shaft tube 2 is set to be 3 mm. Further, a coiled spring 6 having a spring constant of 0.036 kg/mm is arranged so as to set the operating load of a knock body 7 to be 600 g by realizing the condition that the compression from the free length of the spring becomes about 13 mm at writing. When the knock body 7 is pressed with the pressing force of 600 g or more, a knock mechanism, in which a rotating cam 8 is employed, is brought into actuation so as to advance the refill 5 against the springy force of the coiled spring 6, resulting in extending the pen point part 4 through the tip opening part 2a of the shaft tube and then keeping the extended state for realizing writable condition. When the knock body 7 is pressed again, the pen point part 4 is retracted from the tip opening part 2a of the shaft tube. |
