Thermal printing apparatus

A thermal printing apparatus comprising:

• drive means actuated to move a carriage along a platen;
• a thermal print head supported on said carriage so as to be selectively placeable at either of a printing position and a non-printing position;
• a ribbon cassette detachably mounted on said carriage and including a ribbon spool around which a thermal transferable ribbon is wound;
• a rotatable spool shaft mounted on said carriage and engageable with said ribbon spool to rotate said ribbon spool;
• means for transmitting rotational force from said drive means to said spool shaft, said transmitting means having a first position wherein rotational force generated by actuation of said drive means is transmitted to said spool shaft, and a second position wherein transmission of said rotational force to said spool shaft is interrupted, said transmitting means being set at said first position when said thermal print head is placed at said printing position and at said second position when said thermal print head is placed at said non-printing position;
• means for detecting if a ribbon cassette is mounted on said carriage;
• and
• means, engageable with said transmitting means set at said second position, for holding said transmitting means at said second position when mounting of a ribbon cassette is not detected, regardless of shifting of said thermal print head to said printing position.

A thermal printing apparatus comprising:

• drive means actuated to move a carriage along a platen;
• a thermal print head supported on said carriage so as to be selectively placeable at either of a printing position and a non-printing position;
• a ribbon cassette detachably mounted on said carriage and including a ribbon spool around which a thermal transferable ribbon is wound;
• a rotatable spool shaft mounted on said carriage and engageable with said ribbon spool to rotate said ribbon spool;
• means for transmitting rotational force from said drive means to said spool shaft, said transmitting means having a first position wherein rotational force generated by actuation of said drive means is transmitted to said spool shaft, and a second position wherein transmission of said rotational force to said spool shaft is interrupted, said transmitting means being set at said first position when said thermal print head is placed at said printing position and at said second position when said thermal print head is placed at said non-printing position;
• means for detecting if a ribbon cassette is mounted on said carriage, said detecting means having a contact portion engageable with a ribbon cassette and elastically urged toward a predetermined position to protrude from said carriage when a ribbon cassette is not mounted on said carriage, said contact portion being retracted a given distance from said predetermined position when engaging with a ribbon cassette mounted on said carriage;
• and
• means for holding said transmitting means at said second position when mounting of a ribbon cassette is not detected, said holding means being operatively connected to said contact portion of said detecting means and having a holding position predetermined to engage with said transmitting means set at said second position, said holding means being displaced to said holding position when said contact portion protrudes to said predetermined position;
• whereby said transmitting means can be held at said second position regardless of shifting of said thermal print head to said printing position when a ribbon cassette is not mounted on said carriage.

A thermal printing apparatus comprising:

• means for driving a carriage along a platen;
• a thermal print head supported on said carriage and shiftable between a printing position and a non-printing position;
• a ribbon cassette detachably mounted on said carriage and including a ribbon spool around which a thermal transferable ribbon is wound;
• a rotatable spool shaft mounted on said carriage and engageable with said ribbon spool to rotate said ribbon spool;
• a driving element rotatably mounted on said carriage and connected to said driving means;
• a driven element connected to said spool shaft;
• a release lever pivotally supported on said carriage, said release lever being set at a first position when said thermal print head is placed at said printing position and at a second position when said thermal print head is placed at said non-printing position;
• at least one intermediate element rotatably mounted on said release lever, said intermediate element interlinking said driving and driven elements when said release lever is set at said first position and interrupting interlinking of said driving and driven elements when said release lever is set at said second position;
• a shaft supported by said carriage so as to be movable in a direction substantially perpendicular to a plane within which said release lever pivotally moves, said shaft being elastically urged toward a predetermined position so as to protrude from said carriage and being displaced a given distance from said predetermined position by engagement with a ribbon cassette when the ribbon cassette is mounted on said carriage;
• and
• a disc secured to said shaft and having a peripheral surface engageable with said release lever, said disc holding said release lever at said second position by engagement of said peripheral surface with said release lever when a ribbon cassette is not mounted on said carriage.