Abstract: A method for a charge control and multi-step deflection control type ink jet printer is disclosed which renders halftone by multi-step gradation. When an ink ejected from a nozzle is to be charged, a charging voltage is suitably varied to cause a shift in deflection by a pitch smaller than one dot pitch in the deflection direction, thereby selectively causing dots in the deflection direction to overlap and separate from each other. The pitch for developing the shift is variable to control the overlapping or separating degree of the dots in order to accomplish gradation in numerous densities.

Abstract: A control system for a charge deflection type ink jet printer which prints out one character line of print data by a plurality of strokes on a paper is disclosed. Data associated with odd scanning lines are printed out by one printing stroke of a carriage, then the paper is fed by a predetermined amount, and then data associated with even scanning lines are printed out. Thereafter, the paper is fed by an amount produced by subtracting a number of dots corresponding to a predetermined number of odd or even scanning lines from a number of dots corresponding to the total number of the odd and even scanning lines.

Abstract: A deflection control ink jet recording apparatus is capable of compensating for dislocation of dots at all the deflection steps. A deflection amount is adjusted with respect to two points to determine a correlationship between the amplification gain, charge code and deflection amount, so that an amplification gain and a charge code free from dislocation is set for each deflection step. A charge code compensation value is detected to add it to or subtract it from a predetermined charge code assigned to each deflection step, thereby setting a charge voltage code to be assigned to each deflection step in a printout operation.

Abstract: An ink jet head prints an image by superposing individual dot matrices of at least two colors. A computing unit receives electrical input signals representing the image and generates and feeds corresponding electrical signals representing the individual matrices of the at least two colors to the head means for printing. The computing means includes matrix generator means for generating the matrices in such a manner that the total number of dots to be printed in all of the matrices is limited to a first predetermined value which is less than the maximum possible total number of dots which can be printed in all of said individual dot matrices, and the total number of dots to be printed in the matrices which are formed by superposed dots of different colors is limited to a second predetermined value which is less than said first predetermined value.

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: An apparatus for detecting deflection of a charged ink droplet for use in an ink-jet printer is provided. The present apparatus comprises a support member and an electrode housing containing therein an electrode means for detecting the charge of the ink droplet connected to the support member through a link mechanism, and thus the housing may move relative to the support member. The present apparatus also comprises an adjusting screw which may change the position of the housing relative to the support member after mounting the support member to the base frame of an ink-jet printer. Accordingly, mounting of the present apparatus is greatly facilitated and the electrode assembly may be set in position without difficulty.

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 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: 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.