BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a power supply apparatus and an image forming apparatus, and particularly relates to a circuit of a high-voltage power supply of an image forming apparatus.

Description of the Related Art

An image forming apparatus capable of performing image formation by using a plurality of colors of developers may apply a plurality of high voltages corresponding to the plurality of colors of developers, respectively. Japanese Patent No. 6500544 discloses, as an example of such an image forming apparatus, changing a high voltage by using a plurality of voltage divider circuits that includes a plurality of resistance elements in one voltage supply circuit.

A conventional power supply apparatus requires a plurality of voltage divider circuits in order to feed high voltages, such as the voltage applied to a developing roller and the voltage applied to a developing blade, for each of a plurality of developing apparatuses, and the manufacturing cost and the area of a substrate are increased. As a solution to this problem, there is a method of connecting one of high voltages (High Voltage 1) to a voltage supply circuit. However, in the conventional power supply apparatus, an output voltage higher than the output voltage of the voltage supply circuit cannot be supplied to a voltage divider circuit (High Voltage 2), and there is a limit to the high voltage that can be used. That is, in the conventional power supply apparatus, there is a possibility that the output voltage of High voltage 2 cannot be made higher than High Voltage 1 among a plurality of high voltages, with an inexpensive configuration.

SUMMARY OF THE INVENTION

An aspect of the present invention is a power supply apparatus capable of outputting the voltage of an arbitrary value to a plurality of high voltages with an inexpensive configuration.

Another aspect of the present invention is a power supply apparatus including a voltage generation unit configured to generate a first DC voltage, a voltage-drop element configured to drop the first DC voltage to a second DC voltage, a first resistor connected to a line to which the first DC voltage is output, and a first voltage dividing unit configured to generate a third DC voltage by dividing the first DC voltage with the first resistor, wherein the first voltage dividing unit includes an adjusting unit configured to adjust the third DC voltage so that a potential difference between the second DC voltage and the third DC voltage is within a predetermined range.

A further aspect of the present invention is an image forming apparatus including a power supply apparatus including a voltage generation unit configured to generate a first DC voltage, a voltage-drop element configured to drop the first DC voltage to a second DC voltage, a first resistor connected to a line to which the first DC voltage is output, and a first voltage dividing unit configured to generate a third DC voltage by dividing the first DC voltage with the first resistor, wherein the first voltage dividing unit includes an adjusting unit configured to adjust the third DC voltage so that a potential difference between the second DC voltage and the third DC voltage is within a predetermined range, a photosensitive member on which an electrostatic latent image is formed, and a developing unit including a developing roller configured to adhere toner to the photosensitive member, a regulating member for regulating the toner on the developing roller, and a feeding roller configured to feed the toner to the developing roller, the developing unit developing the electrostatic latent image with the toner to form a toner image, wherein the second DC voltage is applied to any one of the developing roller, the regulating member, and the feeding roller, and wherein among members of the developing roller, the regulating member, and the feeding roller, the third DC voltage is applied to either one of the members to which the second DC voltage is not applied.

A still further aspect of the present invention is an n image forming apparatus including a power supply apparatus including a second resistor connected to a line to which the first DC voltage is output, and a second voltage dividing unit configured to generate a fourth DC voltage by dividing the first DC voltage with the second resistor, a photosensitive member on which an electrostatic latent image is formed, and a developing unit including a developing roller configured to adhere a toner to the photosensitive member, a regulating member for regulating the toner on the developing roller, and a feeding roller configured to feed the toner to the developing roller, the developing unit developing the electrostatic latent image with the toner to form a toner image, wherein the second DC voltage is applied to the regulating member, wherein the third DC voltage is applied to the developing roller, and wherein the fourth DC voltage is applied to the feeding roller.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

