Patent ID: 7726759

Claim:
An image forming apparatus, comprising: a liquid ejection head which has a plurality of nozzles and a plurality of pressure generating elements corresponding to the nozzles, and applies drive signals to the pressure generating elements so as to eject recording liquid from the nozzles in accordance with image data; a plurality of drive waveform generating circuits which are connected to the pressure generating elements and generate the drive signals having an identical waveform for driving the pressure generating elements; a plurality of dummy capacitive loads which are connected to the drive waveform generating circuits; a circuit selection device which selects at least one of the drive waveform generating circuits for applying the drive signals to at least one of the pressure generating elements and the dummy capacitive loads; and a circuit selection control device which sets a reference load capacitance for each of the drive waveform generating circuits, calculates a total number of the pressure generating elements to be simultaneously driven to eject the recording liquid in accordance with the image data, and determines whether a total load capacitance corresponding to the total number of the pressure generating elements to be simultaneously driven is larger than the reference load capacitance, when the total load capacitance is not larger than the reference load capacitance, the wherein; when the total load capacitance is not larger than the reference load capacitance, the circuit selection control device sets one of the drive waveform generating circuits to be used to drive the total number of the pressure generating elements to be simultaneously driven, and sets a dummy capacitance that is a sum of at least one of the dummy capacitive loads to be connected to the one of the drive waveform generating circuits so that a sum capacitive load of the dummy capacitance and the total load capacitance is equal to the reference load capacitance; when the total load capacitance is larger than the reference load capacitance, the circuit selection control device sets at least two of the drive waveform generating circuits to be used to drive the total number of the pressure generating elements to be simultaneously driven, and sets, with respect to each of the at least two of the drive waveform generating circuits which are set to be used, a dummy capacitance that is a sum of at least one of the dummy capacitance loads to be connected to said each of the at least two of the drive waveform generating circuits so that a sum capacitance of the dummy capacitance and a load capacitance corresponding to the pressure generating elements to be simultaneously driven by said each of the at least two of the drive waveform generating circuits is equal to the reference load capacitance; and.