Position detecting device, liquid ejecting apparatus and method of detecting smear of scale

A position detecting device for detecting a position of an object, comprising:

• a light emitting portion that emits light;
• a light receiving portion that receives the light from the light emitting portion;
• a scale that is arranged between the light emitting portion and the light receiving portion, and includes a position detecting pattern and a smear detecting pattern;
• and
• a control portion which determines position from the position detecting pattern and determines smear from the smear detecting pattern,
• wherein the control portion does not determine position from the smear detecting pattern and the control portion does not determine smear from the position detecting pattern;
• wherein the position detecting pattern has a first light transmitting portion for transmitting the light from the light emitting portion and a first light interception portion for intercepting the light from the light emitting portion which are alternately arranged in a detection range of the object;
• and
• wherein the smear detecting pattern for detecting smear of the scale has a second light transmitting portion for transmitting the light from the light emitting portion and a second light interception portion for intercepting the light from the light emitting portion which are alternately arranged.