Abstract: An image forming apparatus includes: a photosensitive roller on which surface is formed an electrostatic latent image that is developed using a developer; a transfer roller for transferring the image developed on the surface of the photosensitive roller to a medium; an applying unit that applies voltage to the transfer roller; a current detecting unit that detects current flowing from the applying unit via the transfer roller and photosensitive roller; and a control unit that causes the applying unit to apply voltages of a first and a second voltage value, and determines a voltage value to be applied by the applying unit to transfer the image to the medium, using a difference between a first current value and a second current value which are current values obtained by the current detecting unit which are based on the first and second voltage values, respectively.

Abstract: A device connected to an IEEE1394 serial bus, having a first LED that lights up when digital signals are being exchanged between a PHY chip and a LINK chip, and a second LED that lights up when digital signals are being exchanged between the LINK chip and the main processor. The user can thereby be informed as to where a fault has occurred in the pathway from the main processor of itself to another connected device.

Abstract: A device connected to an IEEE1394 serial bus, having a first LED that lights up when digital signals are being exchanged between a PHY chip and a LINK chip, and a second LED that lights up when digital signals are being exchanged between the LINK chip and the main processor. The user can thereby be informed as to where a fault has occurred in the pathway from the main processor of itself to another connected device.