Abstract: In an inkjet printing device, at least two kinds of drive waveforms are selectively fed to each of plezoelectric elements for controlling an injection amount of ink to be jetted toward a print medium via a corresponding nozzle. One of the drive waveforms is in the form of a cardiac waveform which has two voltage changing points in one drive period thereof. At the voltage changing point, a sign of slope of voltage variation is inverted. In the cardiac waveform, a voltage at one of the voltage changing points is set lower than a standby voltage, while a voltage at the other voltage changing point is set higher than the standby voltage.

Abstract: Disclosed is a method of driving a piezo-electric type ink jet head for jetting inks out of a nozzle by making use of a distortion of a piezo-electric element. The driving method includes a first step of driving the piezo-electric element so that a meniscus of inks is receded from an initial position of the nozzle to a first position within the nozzle, a second step of driving the piezo-electric element so that the meniscus quickly advances from the first position to a second position within the nozzle, and a third step of driving the piezo-electric element so that the meniscus slowly advances from the second position to the initial position. A particle quantity of ink particles is changed by changing a movement quantity from the first position to the second position in the second step.

Abstract: An electrophotographic recording apparatus includes a photosensitive drum on which an electrostatic latent image can be written, a developing device for developing the latent image of a charged visible image with a one-component developer, and a transferring device for electrostatically transferring the charged visible image from the drum to a sheet or paper. The developing device has a conductive foam rubber roller for entraining the developer to form a developer layer therearound and for bringing the layer to the drum for the development of the latent image, a conductive blade resiliently engaged with the foam rubber roller for uniformly regulating a thickness of the developer, and an electric source for applying electric energy to the blade to electrically charge the developer layer by a charge-injection effect.

Abstract: An image forming apparatus capable of preventing unnecessary adhesion of a developer to an uncharged region of a latent image carrier. The image forming apparatus includes an endless latent image carrier, a charging unit for charging the latent image carrier, a latent image forming unit for forming a latent image on the latent image carrier charged, a developing unit for developing the latent image formed on the latent image carrier with a developer by supplying the developer to the latent image carrier under application of a developing bias voltage, and a transfer unit for transferring the image developed on the latent image carrier to a sheet.

Abstract: A toner image transferring device has a roller formed of a conductive rubber foam material having a resistivity of more than 10.sup.7 .OMEGA.cm. In a toner image transferring process, a constant current is applied to the roller, whereby a charged toner image can be transferred to a sheet or paper at a desired toner transfer efficiency regardless of a size of the paper or sheet. To remove a toner pollution of the roller, a constant voltage having a polarity opposite to that of the charged toner is applied to the roller. The roller is constituted such that pore openings appear over a surface of the roller, whereby a residual part of a toner polluting the roller will not leave a stain on a rear surface of the sheet or paper.

Abstract: A toner image transferring device is applied to, for example, an electrophotographic printer for electrostatically transferring a charged toner image from a photosensitive drum to a sheet or paper. The device encompasses a transfer charger disposed near the drum to form a clearance therebetween for feeding an electric charge to the sheet or paper through which the sheet or paper is passed, an electric source for supplying an electric energy to the transfer charger to give the sheet or paper an electric charge having a polarity opposite to that of the charge of the toner image, and a controller for controlling the electric energy output from the electric source the transfer charger so that a leading edge of the sheet or paper can be prevented from being excessively charged.