Patent ID: 7040819

Claim:
A stable area detection device for a platen gap formed between a head and an upper surface of a platen, in a platen gap adjustment device, the platen gap adjustment device comprising: a carriage guide shaft, a guide shaft gear fixed to an end of the carriage guide shaft, a gap adjuster cam rotatable integrally with the guide shaft gear and formed in a shape to change the platen gap in a plurality of platen gap stages, a cam follower for the gap adjuster cam, and a drive motor for driving the guide shaft gear to rotate, wherein the carriage guide shaft is moved relatively to the platen so that the platen gap is adjusted by driving the drive motor to rotate the gap adjuster cam, the gap adjuster cam is configured so as to provide a plurality of stable areas corresponding to the platen gap stages where the platen gap is constant while a rotational phase of the gap adjuster cam varies in a predetermined range and a plurality transition areas where the platen gap changes between the stable areas as the rotational phase of the gap adjuster cam varies; wherein a stable area detection sensor is provided so as to face to a rotational member which rotates synchronously with the gap adjuster cam, and a detection object which corresponds to the stable areas of the platen gap is provided on the rotational member and is detected by the sensor.