Abstract: During a method for manufacturing an ink-jet print head, piezoelectric element bars are fixed to a base plate. Then, two corners of the piezoelectric element bars are cut. The bare are then diced to be separated into individual piezoelectric elements.

Abstract: To increase the size of dot printed on a print medium with an on-demand multi-nozzle ink jet head, at least two unit pulses are applied in succession to a piezoelectric element which varies the volume of an ink chamber. The unit pulse has a pulse width substantially equal to a period of Helmholtz natural oscillation determined based on dimensions, materials, and physical properties of an ink channel and the piezoelectric element and other components relating to oscillation. An off duration between adjacent unit pulses applied in succession to the piezoelectric element is preferably set one fifth to one fourth of the unit pulse width.

Abstract: To eliminate influence of cross-talk in an on-demand multi-nozzle ink jet head, drive pulses to be applied to piezoelectric elements for driving nozzles aligned in a row are individually adjusted so that the nozzles eject ink droplets at the same speed when the nozzles are driven simultaneously. To the piezoelectric elements which are deactuated during printing, a dummy drive pulse having a voltage level in a range from 50 to 75% of a minimum voltage for ejecting an ink droplet is applied, whereby the ejection speed achieved when individual nozzles are driven approaches the ejection speed achieved when all nozzles are driven simultaneously. As such, the print quality is improved.

Abstract: A solid-ink printing original plate which comprises a substrate and an image comprising ink dots formed on the substrate, and which is produced by a process comprising the steps of: melting a solid ink that is a solid at a room temperature; and jetting the melt of the solid ink onto a substrate to form ink dots, wherein the solid ink has a penetration index of not more than 5 at a room temperature. Also disclosed is a process for producing the solid-ink printing original plate.

Abstract: A solid-ink printing original plate which comprises a substrate and an image comprising an ink dot formed on the substrate, and which is prepared by a process comprising the steps of: melting a solid ink that is a solid at a room temperature; and jetting the melt of the solid ink onto a substrate to form an ink dot, wherein the ink dots that have solidified on the substrate have an ink dot height of at least 5 &mgr;m, and a ratio (aspect ratio) of the ink dot height to the minor axis size of the ink dot of from 0.05 to 0.5. Also disclosed is a process for producing the solid-ink printing original plate.

Abstract: A piezoelectric element is driven by a predetermined pulse width in the range of 60 to 100% of the Helmholtz resonance vibration period of an ink vibration system comprising an orifice, a pressurizing chamber, a restrictor, the piezoelectric element, and an elastic material.

Abstract: An ink jet printer has a plurality of piezoelectric elements arranged in a matrix form in which each piezoelectric element is connected between one of TS lines and one of selection lines. The TS lines are connected, one by one and in a time sharing manner, to a voltage source E.sub.1 so as to be enabled. The remaining TS lines are connected to a voltage source E.sub.2 so as to be disabled. The selection lines are selectively connected to a voltage source E.sub.3 so as to be enabled. Non-selected selection lines are connected to a voltage source E.sub.4 so as to be disabled. A selected piezoelectric element connected between enabled TS line and enabled selection line is applied with a driving voltage. A non-selected piezoelectric element connected between enabled TS line and disabled selection line, or between disabled TS line and enabled selection line, or between disabled TS line and disabled selection line, is applied with a non-driving voltage.

Abstract: A method of forming a high-quality image on an elongated recording medium, such as a roll of paper sheet. When an image includes a character which stretches between two print regions, a blank line portion of the image is detected. When image forming operation is performed for forming a portion of the image up to the blank line, sheet feed operations are performed. Then, image forming operation for a remaining portion of the image is performed. Because the sheet feed operation will not be performed in the middle of printing of such image, undesirable broken line or gap will not be formed on the printed image.

Abstract: A printing system having a mechanism for fixing a large scale recording medium in a vertical orientation on an electrostatically adsorption plate provided on a base. The fixing mechanism includes a main holding unit provided on the base, a supplementary holding unit detachably fixed on the main holding unit, and a fixing unit for fixing the supplementary holding unit to the main fixing unit. The supplementary holding unit is first detached from the main fixing unit, and is placed on a tabletop. With this posture, a recording medium is fixed to the supplementary holding unit. Then, the supplementary holding unit holding the recording unit is fixed to the main holding unit. In the fixing operation, the fixing unit automatically changes a held fashion of the recording medium from by the supplementary holding unit to by the main holding unit.

Abstract: An ink jet printer having bubble purging arrangement for discharging bubbles mixed in the ink out of a print head. The print head has a main tank for storing ink, a sub tank for collecting and storing ink, and a manifold fluidly connecting the main tank and the sub tank. The manifold is in fluid communication with the nozzles for supplying ink from the main tank to the nozzles. Three kind of purging modes are provided in accordance with purging position of the print head. Pressurizing pump is selectively connected to the main tank or sub tank or both main tank and the sub tank through a valve arrangement. If the pump is fluidly connected to the main tank only, the ink in the main flows into the sub tank. If the pump is fluidly connected to the sub tank only, the ink in the sub tank flows back into the main tank. By alternating the fluid connection, bubbles mixed in the ink is gradually concentrated at an upper portion of the manifold.

Abstract: In a dot line printer that prints, for example, eight lines of dots with each single scan of a hammer bank, wherein the pins of hammers for printing the first dot line and the eighth dot line or for printing the second dot line and the seventh dot line are shifted from their respective home positions to compensate for an error causing impressions of dots to be made at an unequal pitch in a sheet feed direction as a result of consecutive forward and backward movements of the hammer bank.

Abstract: A dot line printer for carrying out printing on a print paper while shuttling a hammer bank back and forth in a direction to traverse the print paper. To lower the peak level of the current flowed in an electromagnetic coil provided in association with a print hammer and to reduce an electric power consumption, a predetermined number of print hammers are divided, for example, into four groups A, B, C and D. The print hammers belonging to group A are arranged at a constant interval wherein three print hammers belonging to groups B, C and D are interposed between adjacent two print hammers of group A and are disposed in positions displaced toward the leftside group A hammer from their home positions defined by equally spaced apart positions between the adjacent two print hammers of group A. Currents are adapted to flow in the coils of the print hammers belonging to different groups, e.g.

Abstract: In a print hammer assembly for a dot line printer, print pins are attached to the tip ends of print hammers alternately displaced toward left and right by a predetermined distance from a vertical center of the print hammer, wherein comb portions of a front yoke at both sides of the plunger are made to be an equal width. With such an arrangement, the print pins are not deformed horizontally due to imbalanced magnetic force applied to the associated print hammer at the time of magnetization of a permanent magnet.

Abstract: A printing hammer assembly is provided having a plurality of hammer springs arrayed side by side at a predetermined pitch in a shuttling direction of a hammer bank. A front yoke is provided in front of the hammer springs, and a plurality of rectangular grooves are formed at an upper portion of the front yoke so as to receive therein corresponding rectangular plungers provided at the hammer springs. A gap is defined between a side wall of the groove and a side wall of the plunger. The gap is sufficiently large for tolerating inaccurate assembly of the hammer springs and the front yokes. Further, a subordinate front yoke is provided on the front yoke at a position of an array of the grooves.

Abstract: A hammer bank assembly including a hammer base, a plurality of leaf spring type printing hammers, permanent magnets, a comb yoke and electromagnetic coils. The comb yoke has a base portion positioned on the permanent magnets and police portions secured by the base portion and extending from the base portion toward the rear faces of the printing hammers. The pole portions are made of a material capable of providing highly saturated magnetic flux density, and the base portion comprising a plurality of metal plates laminated together and containing another material which provides low saturated magnetic flux density.