Abstract: An ink jet head for compressing ink in an ink chamber to eject a drop of the ink from a nozzle. Ink compressing means for compressing the ink in the ink chamber by expanding and contracting in response to a voltage applied thereto is made of a piezoelectric high molecular substance. The ink compressing means comprises a single thin film of polyvinylidene fluoride (PVDF) or two PVDF films bonded together in a bimorph structure. The thin film is curved inwardly toward the ink chamber. Multiple nozzles are arranged in a predetermined direction. The PVDF film expands and contracts in a direction parallel to the direction of arrangement of the multiple nozzles.

Abstract: An ink receptacle for an on-demand type ink jet printer in which an ink reservoir for storing ink which is to be ejected from an ink jet head is mounted on a carriage. A relatively thick flat housing which is made of non-flexible resin and open at one surface and a single flexible film are bonded together, the film covering the open side of the housing. The housing and the film cooperate to define a relatively large first ink chamber having an opening which is open to the outside and a relatively small second ink chamber also having an opening which is open to the outside. That part of the film which covers the first chamber is deformable to vary the volume of the first chamber corresponding to an amount of ink remaining in the chamber.

Abstract: An ink jet head for compressing ink in an ink chamber to eject a drop of the ink from a nozzle. Ink compressing means for compressing the ink in the ink chamber by expanding and contracting in response to a voltage applied thereto is made of a piezoelectric high molecular substance. The ink compressing means comprises a single thin film of polyvinylidene fluoride (PVDF) or two PVDF films bonded together in a bimorph structure. Multiple nozzles are arranged in a predetermined direction. The PVDF film expands and contracts in a direction parallel to the direction of arrangement of the multiple nozzles.

Abstract: An ink jet printing apparatus is disclosed in which part of ink droplets ejected from a nozzle of an ink ejection head and unused for printing purpose is caught by a gutter and returned to an ink supply source through an ink circulation path to be reused. The ink is partly shunted for disposal while fresh ink is supplied to the ink supply source in proportion to the amount of ink disposal, thereby maintaining the ink viscosity always at a proper value. For the disposal of the ink, a three-way solenoid operated valve is opened periodically for a predetermined period of time or, alternatively, ink droplets ejected from the nozzle are deflected to be caught by a gutter which is independent of the first gutter for routing to disposal means. The amount of disposal is determined by a pressure of ink fed to the nozzle and/or a temperature of ink in the neighborhood of the nozzle.

Abstract: A support mechanism used for securely mounting a head, a charging electrode and a deflection electrode of an ink jet printer on a carriage. The mechanism includes a hollow cylindrical first holder for detachably holding the head and the charging electrode independently of each other, and a second holder for detachably holding the deflection electrode. The head, charging electrode and deflection electrode are readily mounted and demounted from their associated holders.

Abstract: In an ink jet printing apparatus wherein an ink ejection head is loaded on a carriage and, while the carriage moves relative to a sheet of paper, ink droplets are ejected from the head to be charged and deflected to impinge on the sheet of paper, a shape or a position of a conductive member carried on the carriage is varied to develop an electric field which is asymmetrical with respect to a predetermined plane in which charged ink droplets coming out from a charging electrode are to be deflected. The conductive member is constituted by a cover of the carriage, a shield plate, a gutter, a compensating electrode plate, a deflection electrode or the like.

Abstract: Depending upon a position in a dot matrix where an ink drop is to be deposited, the velocity imparted to that ink drop is controlled. The ink drop is charged by a charge electrode impressed with a constant charging voltage and deflected by a pair of electrodes impressed with a constant deflection voltage so as to be placed at an given point.

Abstract: In an ink jet printer of the type wherein an ink jet nozzle continuously ejects the train of ink droplets and only ink droplets which are directed towards a recording surface are electrically charged and deflected by a pair of deflection electrodes so as to dot-form a character, a pair of auxiliary or compensation electrodes are provided in order to eliminate or control the inclination relative to the vertical line of dot-formed characters due to the relative speed between the recording surface and the ink jet nozzle.

Abstract: In an ink jet printing device wherein when a number of n nozzles are sequentially arranged in the direction of transport of recording paper and spaced apart from each other by a distance corresponding to m characters or ink dots so that when ink dots discharged from each nozzle are arranged in one column on the recording paper in the direction of transport thereof, the adjacent ink dots have a very small spacing, but they are nearly in contact with each other, a modulo-m address counter is stepped so as to store data in a memory while a modulo-n address counter is stepped to read out data. Thus positional deviations between nozzles may be compensated.

Abstract: Depending upon a position in a dot matrix where an ink drop is to be deposited, the velocity imparted to that ink drop is controlled. The ink drop is charged by a charge electrode impressed with a constant charging voltage and deflected by a pair of electrodes impressed with a constant deflection voltage so as to be placed at an given point.

Abstract: Minute ink particles are ejected from a nozzle (16) in the form of a stream and electrostatically charged. The widths of pulses fed to an electrode (21) which applies the charge are varied in accordance with a desired printing density. A voltage is applied to a first deflection electrode (23) when it is desired to print a dot to deflect ink particles onto a moving sheet (22). An alternating voltage is applied to a second deflection electrode (27) to deflect the ink particles perpendicular to the deflection direction of the first deflection electrode (23) so as to form a cluster of ink particles on the sheet (22) having a diameter equal to a desired dot size.

Abstract: A voltage is applied to a plurality of electromechanical transducers mounted on a plurality of nozzles, respectively, so that a meniscus may be formed at the nozzle tip. One or more opposing electrodes or rear transducers are disposed in opposed relationship with a predetermined number of nozzles, respectively, the number of the opposing electrodes or rear transducers being less than that of the nozzles. When one of the opposing electrodes or rear transducers which is in opposed relationship with the nozzle whose transducer is applied with a voltage is applied with a voltage, an ink drop is issued. The opposing electrodes are applied with a voltage in a time-division manner.

Abstract: An ink-jet recording apparatus wherein the ink jet is issued from an ink head or manifold and broken into drops. The selected ink drop is charged and made to pass through a first deflection means which deflects the charged ink drop in two mutually perpendicular directions, one being in parallel with a main scanning direction while the other being perpendicular to said direction. After leaving the first deflection means, the charged ink drop passes through a second deflection means which can cancel or nullify the deflection of the charged drop in said other direction, leaving the charged drop subject to the deflection in said main scanning direction so as to be steered to a predetermined point on a recording medium. The ink drops which are not used are not charged and travel a straight trajectory so as to be trapped by a gutter between the first and second deflection means.

Abstract: An ink-jet printer wherein a pair of horizontal deflection electrodes and a pair of vertical deflection electrodes are disposed in the order named in the direction of travel of ink drops so that the charged ink drops may be deflected in the horizontal direction depending upon the charge on the respective ink drops, but the vertical deflection electrodes are so arranged or shaped or applied with such deflection voltage that the charged ink drops may be deflected in the vertical direction by the same amount, regardless of the charge on the respective ink drops, away from the trajectory of the uncharged ink drops, whereby the ink dots may be aligned along a horizontal line.

Abstract: In an ink jet recording apparatus including a carriage operative to move in scanning motion for printing characters and symbols on a printing surface and supporting thereon a single printing head having a plurality of ink jet nozzles or a plurality of printing heads each having a single ink jet nozzle, the printing surface is formed as a curved surface and the printing head or heads are constructed such that ink can be ejected radially with respect to the center of curvature of the curved printing surface. The vertical spacing between dots formed by ejected ink can be adjusted by moving the printing head or heads relative to the printing surface to thereby adjust the spacing between the printing surface and the printing head or heads, and the transverse spacing between the dots can be adjusted by adjusting the scanning speed of the printing head or heads or the ink ejecting timing.

Abstract: A first ultrasonic transducer is normally energized so that the ink jet normally emerging through a nozzle of an ink manifold containing the pressurized ink may break into an ink drop within a charge electrode and the charged ink drop may be deflected by a pair of deflection electrodes so as to travel toward a gutter. In response to the ink-placement signal a second ultrasonic transducer is de-energized when it has been energized in phase or in opposite phase with the first ultrasonic transducer when the second ultrasonic transducer has been de-energized so that the formation of each ink drop may occur outside of the charge electrode and the uncharged ink drop may travel to strike against a recording medium.

Abstract: Ink is fed to an ink jet printing head (12) from which it is ejected into a sheet of printing paper (19). A plurality of capacitive ultrasonic vibrators (29), (31) are provided inside the printing head (12) to atomize ink therein prior to ejection. The ultrasonic vibrators (29), (31) are connected in parallel with each other and also to an inductor (48) to constitute a resonant circuit. An electrical drive signal is applied to the resonant circuit, the frequency of the drive signal being equal to the resonant frequency of the resonant circuit.

Abstract: A charging phase control device for an ink jet recording device wherein the ink droplets are positively or negatively charged in the recording mode. In the charging phase detection mode an ink droplet charging electrode is so energized that more than two successive ink droplets may be negatively or positively charged and one or more ink droplets which immediately follow said more than two successive, negatively or positively charged ink droplets may be uncharged or positively or negatively charged. The negatively or positively charged ink droplets repel each other and attract the uncharged or positively or negatively charged ink droplets so that they coalesce into large ink droplets. Therefore the distance between an ink head and an ink droplet detection means may be reduced, the ink jet recording or printing device may be made compact in size and light in weight; and ink droplet charging phase may be detected and controlled with a higher degree of accuracy.

Abstract: A first ink tank (17) is attached to a movable ink jet printing head (12) for supplying ink thereto. A second ink tank (28) which is larger than the first ink tank (17) is fixedly mounted at an end of a carriage (19) which supports the printing head (12). After the printing head (12) prints a line, a print end signal causes a sensor (33) to sense the amount of ink in the first ink tank (17). If the amount is low the printing head (12) is moved so that a connector (31) of the first ink tank (17) mates with a connector (29) of the second ink tank (28) and ink is urged to flow from the second ink tank (28) to fill up the first ink tank (17). The amount of ink in the first ink tank (17) is again sensed and if it is still low, indicating that the amount of ink in the second ink tank (28) is also low, an annunciator (41) is energized to urge the apparatus operator to fill the second ink tank (28) with ink.

Abstract: An ink ejection head is moved to an inoperative position when the apparatus is de-energized. An electrical solenoid moves the cap to a retracted position as the ink ejection head approaches the inoperative position and another electrical solenoid or a spring moves the cap into injection orifice sealing engagement with the ink ejection head when the ink ejection head reaches the inoperative position. Damping means are disclosed for preventing impact of the cap against the ink ejection head which would cause erroneous ink ejection and resilient means are disclosed for ensuring sealing alignment of the cap against the ink ejection head.