Patent ID: 8594540

Claim:
A development device to develop an electrostatic latent image formed on a latent image carrier, the development device comprising: a developer container for containing toner; a toner carrier disposed facing the latent image carrier, the toner carrier including a first group of electrodes and a second group of electrodes that together form a capacitor; a toner supplier disposed in the developer container, to supply the toner to a surface of the toner carrier; an electrical field generator to generate an electrical field for causing the toner to hop along the surface of the toner carrier, the electrical field generator including: a positive-phase pulse voltage generation circuit to generate a positive-phase pulse voltage applied to the first group of electrodes, a negative-phase pulse voltage generation circuit connected in parallel to the positive-phase pulse voltage generation circuit, to generate a negative-phase pulse voltage applied to the second group of electrodes, a first power source that is a DC power source floating from a ground voltage, the first power source supplying a bias to the positive-phase pulse voltage generation circuit and the negative-phase pulse voltage generation circuit to set a peak value of the positive-phase pulse voltage and the negative-phase pulse voltage, a second power source that is a DC power source connected between a lower potential side of the first power source and the ground voltage, to output a variable level of voltage, the voltage having a polarity identical to a polarity of a charge of the toner, a first diode having an anode connected to the lower potential side of the first power source and a cathode connected to an output terminal of the positive-phase pulse voltage generation circuit, and a second diode having an anode connected to the lower potential side of the first power source and a cathode connected to an output terminal of the negative-phase pulse voltage generation circuit, the positive-phase pulse voltage generation circuit including a first switching element, a second switching element, and a first current regulating resistor serially connected between terminals of the first power source, and the negative-phase pulse voltage generation circuit including a third switching element, a fourth switching element, and a second current regulating resistor serially connected between the terminals of the first power source, the first group of electrodes connected between the first and second switching elements of the positive-phase pulse voltage generation circuit, and the second group of electrodes connected between the third and fourth switching elements of the negative-phase pulse voltage generation circuit, thus forming a bridge configuration, wherein, when the positive-phase pulse voltage is applied to the first group of electrodes, the first and fourth switching elements are turned on, and, when the negative-phase pulse voltage is applied to the second group of electrodes, the second and third switching elements are turned on.