Patent ID: 7494294

Claim:
A pen with dual extension/retraction cartridges, comprising: a first pen tube with a first pen tip portion and a first pen end portion, wherein the first pen tube is disposed with a first writing insertion plate inside the tube near the first pen tip portion and the first pen end portion is disposed with a guiding tube which has an elastic plate disposed at one side and two positioning rings disposed at the peripheral of the guiding tube; a second pen tube with a second pen tip portion and a second pen end portion, wherein the second pen tube is disposed with a second writing insertion plate inside the tube near the second pen tip portion, and the second pen end portion is disposed with a guiding slot having a positioning hole passing through at one side and a fastener disposed around the peripheral of the guiding slot so that the guiding tube of the first pen tube is inserted into the guiding slot and the positioning fastener is engaged with the positioning hole via the elastic plate and the fastener is engaged with the two positioning rings; two cartridges inserted onto the first and the second writing insertion plates of the first pen tube and the second pen tube respectively; and after the cartridges are inserted into the first and the second pen tubes, the first pen tube is inserted into the guiding slot via the guiding tube to have both pen tubes combined, then two cartridges are hidden inside the two pen tubes respectively and engaged with the peripheral of a positioning hole via the positioning fastener and the fastener is against the exterior of a front positioning ring to stabilize the positions of both pen tubes, thus a little force is exerted to have the fastener cross the front positioning ring to close the two pen tubes so that the fastener is engaged with rear positioning ring to fix, then both cartridges are exposed out of the two pen tubes for writing.