Ricoh Company, Ltd.

Rocoh Company, Ltd.

Toshitaka Hirata

Hiromichi Komai

Tomoaki Nakano

Toshio Inada

Masami Kadonaga

Masanori Horike

Yutaka Ebi

Tetsuro Hirota

Osamu Naruse

Kyuhachiro Iwasaki

Koichiro Jinnai

Chuji Ishikawa

Toshio Kawakubo

Shigeyuki Araki

Minoru Ameyama

Takao Fukazawa

Kouji Izumi

Syuzo Matsumoto

Shizuo Yokoyama

Kenichi Ichikawa

Haruyoshi Masui

An ink jet printing head driving method includes steps of: applying a voltage falling edge of a first pulse signal to cause a piezoelectric element to contract so that a capacity of a liquid passage is increased so as to supply ink to the liquid passage; applying a voltage rising edge of the first pulse signal to cause the piezoelectric element to expand so that the capacity of the liquid passage is decreased, for discharging an ink droplet through a discharge port, the first pulse signal having a first pulse width and a first peak voltage amplitude; and applying a voltage rising edge of a second pulse signal to the piezoelectric element after a predetermined delay time has elapsed since application of the first pulse signal for discharging the ink droplet, a pulse width of the second pulse signal being smaller than the first pulse width, and a peak voltage amplitude of the second pulse signal being equal to the first peak voltage amplitude.

Method of driving ink jet printing head

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.

Ink jet head

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.

Method of driving ink jet type printing head

An ink jet printer includes a pump which pressurizes an ink to be supplied to a nozzle, which projects an ink jet. When the ink pressure which is supplied to the nozzle exceeds a given value or when the deflection of the ink jet is improper, pressure oscillations are applied to the nozzle by alternately and repeatedly driving and ceasing to drive the pump in order to remove a plugging of the nozzle. If the repeated operation does not result in a reduced ink pressure, the nozzle is connected to a low pressure ink vessel, causing the pressure prevailing within the nozzle to be reduced.

Ink jet printer

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.

Ink jet printing apparatus

An image signal processing method in which an image light is projected on photoelectric conversion means and an image signal produced by said photoelectric conversion means is changed into an image signal in a binary form. The amplitude and level of an information signal to be binarily processed are kept nearly constant according to the invention and consequently the binary processing can be performed with a least leakage of informations.

Apparatus for and method of processing the image signal

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Tokyo, Japan

Toshitaka Hirata