Ink jet printing has been suggested for use in facsimile systems wherein a facsimile receiver is adapted to receive a signal, typically over a communications link such as a telephone line, and print out a copy or facsimile of a document which is being scanned at a facsimile transmitter in a remote location. However, in most facsimile receivers and transceivers in commercial use today, ink jets are not employed. Rather, these facsimile receivers employ electrosensitive paper used in conjunction with a stylus which may be undesirable since the paper itself is specially treated and therefore somewhat expensive. Moreover, the paper of this type can produce unpleasant odors during marking.
Despite the disadvantages of electrosensitive paper, marking by ink jet has not yet achieved commercial acceptance in facsimile applications. One possible explanation for the failure of ink jets to assume commercial importance in facsimile applications is the difficulty associated with maintenance of the ink jet and related apparatus by relatively unskilled operators or attendants. More particularly, any ink jet apparatus necessarily requires a replenishing of the ink supply. Such replenishing in various ink jet printers has required an operator to disconnect the supply from the ink jet and replace the supply. The ink jet itself which is typically rather expensive remains permanently mounted on the scanning head of the receiver so as to assure proper drop placement.
Another possible reason for the failure of the ink jet to be accepted in facsimile systems is the requirement that the ink jet be ocassionally purged to remove dried ink or other debris from the orifice or nozzle of the ink jet. Since the orifice or nozzle of the ink jet is extremely small and its size is of the utmost importance in the formation of ink droplets which emerge from the jet, it will be readily appreciated that the orifice must be kept clear of any debris which might interfere with that drop forming function. It will further be appreciated that providing this purging function complicates the ink jet system which can create a further opportunity for operator-induced failure of an ink jet system if the operator is required to manipulate purging apparatus.
In ink jets of the demand or impulse type, it is also necessary to provide apparatus for priming the ink jet, i.e., in effect pumping a quantity of ink to a chamber so as to assure that ink will be present for ejection through the droplet forming orifice when a transducer is energized on demand. The priming apparatus which may be similar to the purging apparatus in an impulse ink jet will similarly complicate the apparatus and can create potential operator difficulties in attending to the ink jet apparatus.
In U.S. Pat. No. 3,961,337--Jung et al, an ink jet printer of the continuous type is disclosed wherein it is suggested that the ink supply as well as the ink jet may be replaced when it is time to replenish the ink supply. As disclosed therein, the ink jet is mounted on a movable head and spaced a distance from a stationary ink reservoir or supply which is connected to the ink jet by a hose. As a consequence, replacement of the ink jet and the ink supply requires the operator to remove the ink jet and also remove the separate ink supply. The Jung printer also employs a catcher and deflection plates which remain permanently mounted on the head. Assuming the operator is able to perform this chore, the operator must then accurately mount a replacement ink jet jet on the movable head in alignment with the permanently mounted catcher and deflection plates and also mount the ink supply in its stationary location. Moreover, the operator must couple the ink supply system to the associated pumping mechanism. Such an apparatus has not found commercial acceptance in a facsimile system.
USPTO Backgrounds
USPTO Backgrounds