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: A printer head for use in an on-demand type ink-jet printer includes a main body which is provided with a nozzle opening, through which ink is ejected to form flying ink droplets, and an ink passage extending to the nozzle opening for storing ink therein to be ejected through the nozzle opening. The printer head includes a pusher unit, which is supported away from the main body and which produces a deflection in response to a print signal supplied thereto, and a connection rod connected between the pusher unit and the main body. Thus, when the pusher unit produces a deflection, which is transmitted to the main body through the connection rod to change the volume of the ink passage, so that the ink inside the passage is partly ejected through the nozzle opening to form ink droplets.

Abstract: An ink jet printing apparatus capable of removing bubbles introduced into ink which is routed from an ink supply cartridge to a plurality of nozzles. A head holder adapted to support a head, which has the nozzles, is formed with an ink supply path for delivering ink from the ink supply cartridge to the nozzles. The ink supply path branches into an upwardly extending passageway and a downwardly extending passageway. The ink is supplied to the nozzles by way of the downward passageway. A check valve is positioned in the upward passageway for trapping bubbles entrained by the ink. The bubbles trapped by the check valve are discharged by a suction pump.

Abstract: A unique arrangement of a multi-nozzle head which is suitable for use with an ink on-demand type ink jet printer. A flat head base is formed with a plurality of nozzles and ink compressing chambers associated therewith by etching. The ink compressing chambers are divided into a plurality of groups which are positioned on imaginary lines, which are individually inclined a predetermined angle with respect to an intended direction of ink ejection.

Abstract: A color plotter capable of printing out alphanumeric characters and the like at a high speed in addition to color plots is disclosed. A print head assembly comprising ink ejection heads is partly allocated to multicolor plots and partly to single-color characters and controlled to selectively print out graphic data and character data on a sheet as desired. The print head assembly is mounted on a carriage. In a plotter mode, the carriage and sheet are driven each in a reciprocal movement in directions perpendicular to each other with the plot section of the print head assembly energized. In a printer mode, the character section of the print head assembly is energized in response to input pixel data while the carriage is stroking.

Abstract: An ink jet printing system for printing an image in the form of dots produced by ink droplets on a recording medium is provided. The present ink jet printing system is characterized by detecting the presence of air bubbles in the ink inside an ink chamber beyond a predetermined level and removing these air bubbles by pulling the air-ink boundary into the ink chamber thereby transferring the air bubbles to the air. The present ink jet printer allows to produce ink droplets of uniform characteristics since air bubbles are removed from the ink as soon as they are detected.

Abstract: A new nozzle structure is disclosed for an ink ejection head of an electric field on-demand type ink jet printer. A plurality of circular nozzles and first electrodes integral with the nozzles are arranged along the widthwise direction (X direction) and feed direction (Y direction) of a sheet of paper. A plurality of lead terminals are individually connected to the arrays of the first electrodes each of which extends in the Y direction. Second electrodes are located at the rear of the first electrodes and individually connected to the arrays of the first electrode each of which extends in the X direction. A third or counter electrode is positioned in front of the first electrodes and at the back of the sheet. Each of the second electrodes is mounted on a nozzle plate or a nozzle support.

Abstract: An air removal unit (36) is disposed in a conduit (35) leading from an ink reservoir (34) to an ink ejection head (37). The amount of entrained air in the ink in the head (37) is sensed, and a heater (39) connected to the removal unit (36) is energized to heat the ink and boost the air removal efficiency when the amount of entrained air is above a certain value. The air removal unit (36) includes a container (47) and partitions (51), (52) provided in the container (47) to define chambers. The ink flows upwardly and downwardly through the chambers and the entrained air rises into a collection chamber (54) from which it is vented to the atmosphere.

Abstract: In the pressure, on-demand type ink-jet printers or the like, the driving voltages applied to respective electrostrictive means of print head or nozzle units are shifted in time so that constructive interferences of sound waves produced by the pressure waves which in turn are generated bu respective print head or nozzle units may be avoided, whereby the over-all intensity of sound waves and consequently noise may be remarkably suppressed.

Abstract: An ink clog is automatically sensed in an ink ejection nozzle (14). The clog is cleared by moving a cap (28) into covering engagement with the nozzle orifice, causing solvent to flow through the nozzle (14) from the cap (28) to dissolve the clogged ink and subsequently causing air to flow through the cap (28) and nozzle (14) to purge solvent therefrom.

Abstract: A device for removing air bubbles formed and trapped in an ink chamber of an ink-jet print head, said device comprising a means for sensing the existance of air bubbles in the ink chamber, a means responsive to the output signal from the sensing means for replacing the ink in the ink chamber with an agent having a low surface tension, and a means for replacing the agent filled in the ink chamber with the ink.

Abstract: An analog delay circuit wherein an analog signal to be delayed as well as a reference voltage signal the voltage level of which is previously known are applied to an analog delay element comprising BBD, CCD or the like, and the reference signal is derived from the output of the analog delay element so that the reference signal or a signal associated therewith may be used for controlling a voltage to be applied to the analog element so as to set a bias voltage thereof.

Abstract: A drive circuit for an ink-on-demand type ink jet discharging head used for generating characters and patterns with the jet of ink. A driving pulse delivery circuit is conneted to the ink jet discharging head for delivering it with the driving pulses for causing it to discharge the jet of ink. A control circuit for controlling the voltage of the driving pulses applied to the switching element is connected to a switching element of the driving pulse delivery circuit. The voltage of the driving pulses applied to the switching element may be maintained higher than that of the pulses applied in the normal operation for a predetermined time interval after the driving pulse delivery circuit and the control circuit are turned on so that the pulses applied to the head are stronger than those applied in the normal operation.

Abstract: An ink jet head (47) is moved relative to a recording surface (11). Print signals are applied to the ink jet head (47) from a computer or the like (22) causing the ink jet head (47) to eject ink onto the recording surface (11). The amount of ink ejected and thereby the density of printing correspond to the magnitudes of the print signals. The ejection velocity of the ejected ink increases with the magnitudes of the print signals. The timing of ink ejection is adjusted in accordance with the magnitudes of the print signals in such a manner that the ejected ink is incident on the printing surface (11) at a same position at all velocities of ink ejection.

Abstract: A circuit for driving an ink-on-demand type ink jet head comprising a comparator for comparing the video signal with a reference signal and delivering a high-level output when the level of the video signal is higher than or equal to said reference voltage or a low-level output when the level of the video signal is lower than the reference voltage; a pulse synchronization circuit for receiving the output of the comparator and a printing sync pulse and delivering an output pulse in synchronism with the printing sync pulse when the pulse synchronization circuit has received said high-level or low-level output from the comparator; and a sample-hold circuit for holding a peak value of the video signal, the output of the sample-hold circuit being delivered to a high-voltage energization circuit for driving an ink jet head, the output of the pulse synchronization circuit being applied to the sample-hold circuit so as to reset the peak value held thereby.

Abstract: An ink filter (15) is provided in an ink supply conduit (12). First and second electrodes (21), (22) are disposed in the conduit (12) upstream and downstream of the filter (15) respectively. A sensor means (23), (24), (27), (28), (32) measures an electrical parameter such as the electrical resistance, capacitance or the like between the electrodes (21), (22) which varies as a function of the degree of clogging of the filter (15). An indicator (34) such as a light or lights (36), analog meter (33) or the like indicates the magnitude of the electrical parameter and thereby whether the filter (15) is clogged or unclogged.

Abstract: First, second and third ink ejectors eject ink of three primary colors in superposition onto a sheet of paper being moved relative thereto in response to first, second and third electrical color signals respectively. Circuit means are provided to sense initiation and termination of the signals. Upon simultaneous initiation of one of the signals and termination of another of the signals, the circuit means delays ink ejection from the ejector corresponding to the signal which was initiated for a predetermined length of time. This prevents color mixing at the boundary of the colors which would produce an erroneous color.

Abstract: An ink ejection nozzle acts as one electrode and is arranged to eject ink against another electrode during an ink ejection test of the nozzle. The ink stream electrically connects the electrodes when the ink is being ejected normally, whereby the ink flow rate is analogous to the electrical impedance or capacitance between the electrodes. If the nozzle is clogged with an ink deposit so that the flow rate is insufficient, the system ejects a solvent through the nozzle to dissolve the deposit. The flow rate of the solvent is also sensed and the solvent ejection is terminated when the solvent flow rate is sufficient. Ink is then again ejected to purge the solvent from the nozzle.

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.

Abstract: Ink is fed into an ink chamber in an ink ejection head. An ejection orifice communicates with the ink chamber. An electrostrictive plate defines a surface of the ink chamber and is strained to decrease the volume of the ink chamber when an electrical pulse is applied thereto to cause ink to be ejected through the orifice. The apparatus is inoperative if there is no ink in the ink chamber or there are air bubbles in the ink in the ink chamber. In such a case the voltage across the electrostrictive plate has an oscillating component, the oscillating component being damped out when the ink chamber is completely filled with ink. A sensor is provided to detect the oscillating component and generate a signal indicating said detection. Circuit means are provided to increase the magnitude of the pulse when the oscillating component has a magnitude indicating that the apparatus is not inoperative but some bubbles are present in the chamber.