Abstract: An ink jet head used for pulsed droplet ink jet printer uses a grooved piezo-electric element. The piezo-electric element includes a plurality of grooves, diaphrams and actuators. The actuator and two grooves at both sides of the actuator, filled with stuffing material, covers a corresponding one of passages. Therefore, even if the stuffing material moves when the actuator is energized, an interference problem does not occur. Consequently, the flexure force of each actuator can transmit to the corresponding passage to jet ink in the passage via a nozzle.

Abstract: A method of driving an ink jet type printing head is applied to a printing head which has a plurality of channels, a plurality of nozzles provided on ends of the channels and a plurality of piezoelectric elements for varying volumes of the channels in response to driving voltages so as to eject ink from each nozzle having a corresponding channel the volume of which is reduced by a corresponding one of the piezoelectric elements. The method includes the steps of applying a first driving voltage to a first group of piezoelectric elements and a second driving voltage to a second group of piezoelectric elements, and controlling a phase of at least one of the first and second driving voltages so that a predetermined phase difference exists between the first driving voltage and the second driving voltage.

Abstract: A liquid jet recording head includes a flow path member having a plurality of flow paths, each of the plurality of flow paths having an opening surface which opens on the flow path member, an piezo-electric member having a plurality of grooves and piezo-electric elements, each of the piezo-electric elements being formed between adjacent two grooves of the plurality of grooves, the piezo-electric member being connected to the flow path member so that each of the piezo-electric elements is faced to the opening of one of the plurality of flow paths, an elasticity member being filled in each of the plurality of grooves formed on the piezo-electric member, a liquid guide mechanism guiding, to each of the plurality of flow paths, liquid which is supplied by an external liquid supplying mechanism, and jet orifices, each of the jet orifices being provided to an end portion of one of the plurality of flow paths.

Abstract: An ink jet record apparatus for driving a drop-on-demand ink jet head with a piezoelectric element in a printing apparatus. The ink jet record apparatus includes a first drive part for driving and operating the ink jet head in a first operation mode, a second drive part for driving and operating the ink jet head in a second operation mode, a selection part for changing an operation of the ink jet head from the first operation mode to the second operation mode or vice versa, and a control part for supplying a drive signal to the selection part in accordance with input image information, thus allowing a size of ink dots on paper to be adjusted through selection of either the first operation mode or the second operation mode.

Abstract: A device for detecting viscosity of a liquid which varies with time includes a first tank provided with an overflow section for maintaining a predetermined liquid height, and a second tank fluidly communicated to the first tank and provided with a restricted outlet, or orifice. While a liquid is circulated through the two tanks by a pump, a height sensor which is dipped in the liquid in the second tank senses a liquid height in the tank in terms of capacitance. The output of the height sensor is representative of a viscosity of the liquid.

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: An ink supply system of an ink jet recording apparatus of the charge control type including a supply pump for feeding ink under pressure to a recording head, an accumulator for equalizing the pressure of the ink, and valve means for controlling the feeding of the ink under pressure to the recording head. The supply pump, the accumulator and the valve means are located in a piping for supplying the ink in the ink tank to the recording head in the indicated order as seen from the ink tank side. A delivery pump is located in a piping for returning ink to the ink tank from a catcher for recovering the ink ejected through the recording head but not contributing to recording of information with ink drops.

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: In one embodiment of the present invention an ink manifold is divided into a first ink chamber communicated with an ink drop issuing nozzle and a second ink chamber communicated with an ink source and the first ink chamber through a narrow passage. First and second piezoelectric elements are mounted in opposed relationship with the first and second ink chambers, respectively. The second piezoelectric element is normally applied with such a second driving voltage that the ink will not issue through the nozzle. The frequency of a first driving voltage applied to the first piezoelectric element is twice as high as that of the second driving voltage, and the first driving voltage is selectively applied in synchronism with the second driving voltage only during the positive going half cycle thereof so that an ink drop may be issued through the nozzle during the positive going half cycle of the first driving voltage.

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 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.