Patent ID: 8205958

Claim:
A printing apparatus, comprising: a transport unit that transports a medium in a transporting direction; a head that performs recording on a medium using ink and that moves in a moving direction, said head having a plurality of colored-liquid nozzles each ejecting a colored liquid and a plurality of colorless-liquid nozzles each ejecting a colorless liquid; a sensor that moves in said moving direction together with said head, the sensor including a first sensor that detects the edge of said medium and a second sensor that detects the patterns formed on said medium by said head, the first sensor being arranged upstream of the second sensor in the transporting direction; and a controller, the controller controlling the head in such a manner that: each of said plurality of colorless-liquid nozzles respectively form a colorless block pattern on said medium, a plurality of the colorless block patterns are formed on said medium lined up in a straight line in said moving direction and leaving a space between the colorless block patterns adjacent to one another, and said plurality of colored-liquid nozzles apply said colored liquid onto said plurality of the colorless block patterns, the controller controlling said second sensor to detect, while moving once in said moving direction, a degree of smearing of said colored liquid at a position where said colorless block pattern is to be formed in order to detect whether there is a colorless-liquid nozzle that has not ejected said colorless liquid.