Printer assembly with easily loaded paper cartridge

Abstract

An electronic imaging camera includes a printer assembly for providing instant images. Selected special effects may be applied to the images prior to printing. The printer assembly includes a thermal print head and a paper advance roller. A replaceable preloaded paper cartridge is provided for easy replacement of the paper. The housing of the paper cartridge acts as a printing platen for the print head, and rollers in the cartridge maintain friction between the paper and the paper advance roller of the printer assembly. A pivoting print head cover prevents a user from inadvertently coming into contact with the print head when the paper cassette is removed. A rotary encoder gear includes a plurality of spaced lugs which block emissions from a light emitting diode from reaching a phototransistor. As the encoder gear rotates in synchronization with the print head, the phototransistor produces a series of electrical pulses indicative of the print head speed. These pulses are fed back to the printer control circuits to adjust the print head speed. An extended tab on the print head carrier extends into the light path between the light emitting diode and the phototransistor when the print head is in the home position. Accordingly, the same LED/phototransistor combination is used for detecting print head speed and for registering the mechanical home position of the print head.