Importance

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Abstract

The calculator is small enough and well protected enough to be carried in the pocket. In addition to a keyboard 28, circuit board 29, batteries 18 and an LCD data display 91, there is a printer comprising a platen 36 which draws paper from a roll in a compartment 101. A thermal printing head 33 is reciprocated along the writing line by a pin 44 engaging in an eccentric cam groove in a disc 46 rotated by a crown wheel 53 and a pinion 54 on the shaft of a motor. Another cam-follower pin 64 reciprocates a slide 66 which advances the platen incrementally after each traverse of the head 33. A slidable cover 14 is shown open, exposing the printing mechanism and operating a switch which enables the printer. Results appear on the LCD display and are printed. When the cover is slid closed it protects the printing mechanism and disables it via the switch. The calculator can nevertheless be used without the printer, results being displayed only on the LCD display 91. The paper roll is carried in a removable container 132 to which access is obtained by depressing a detent tongue and sliding the cover still further open. Cooperating parts of the container and the calculator frame guide the leading strip of the paper between the platen and print head. When the cover is closed it bends a tongue of the container to nip the paper and immobilize it.

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First Claim