Ink jet recording apparatus and controlling method for recording apparatus

An ink jet recording apparatus provided with a control circuit for controlling the recording operation using a recording head, and a driving circuit for driving the driving source to drive the recording head, comprising:

• the power supply portion of a serial interface to supply power to said control circuit with a first voltage value;
• a power supply unit having a first voltage output circuit for supplying power to said control circuit with a first voltage value, and a second voltage output circuit for supplying power to said driving-circuit with a second voltage value, wherein
• the power supply to said control circuit from said first output circuit and said power supply portion of said serial interface is executed in accordance with the status of the power supply portion of said serial interface.

A method for controlling an ink jet recording apparatus provided with a control circuit for controlling the recording operation using a recording head, and a driving circuit to drive the recording head, comprising the following steps of:

• operating said control circuit in said recording operation with the power supply from the power supply portion of a serial interface with a first voltage value;
• and
• operating said driving circuit by the power supply from said power supply unit with a second voltage value.