Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Publication of BE534422ApublicationCriticalpatent/BE534422A/xx
B43—WRITING OR DRAWING IMPLEMENTS; BUREAU ACCESSORIES
B43K—IMPLEMENTS FOR WRITING OR DRAWING
B43K24/00—Mechanisms for selecting, projecting, retracting or locking writing units
B43K24/02—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions
B43K24/08—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions operated by push-buttons
B43K24/088—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions operated by push-buttons with spreading spring means