Printing machine having a type wheel supporting structure

A printing machine in combination with a cassette housing a type wheel having a central hub which is provided with (i) drive engaging means, (ii) a front projection means, and (iii) a rear projection means, said cassette being detachably mountable at a printing position in said printing machine, said printing machine having means engaging the front projection means of the type wheel when the cassette is in said printing position to urge the type wheel rearwardly and having a selection motor means and said type wheel further having a plurality of spokes extending radially from the central hub thereof and types provided at the free ends of at least some of the spokes, said cassette comprising:

• a rear wall having a hub opening shaped and dimensioned to (i) allow the drive engaging means of the central hub of the type wheel to be drivingly engaged by a selection motor means and (ii) loosely receive said rear projection means of the central hub of the type wheel;
• a front wall connected to the rear wall at least partly to form an integral structure therewith within which the print wheel can rotate, wherein said front wall is spaced forwardly from the rear wall to allow space for positioning the type wheel between said front and rear walls of the cassette, wherein said front wall has a hub opening which is opposite the hub opening in the rear wall and loosely receives said front projection means of the central hub of the type wheel, wherein said cassette is ree of cassette-mounted spring means acting on the type wheel and wherein the spacing between the front and rear walls of the cassette relative to the axial distance between the hub's front and rear projection means is such that at any time at least one of the front and rear projection means is received in the respective hub opening of the respective wall to limit radial movement of the type wheel relative to the cassette.

A printing machine comprising:

• a biasing means acting in an axial direction;
• a cassette housing a rotary type wheel which has a central hub, a plurality of spokes extending radially from said hub, types provided at least at some of said plurality of spokes, first axial projection means at a first surface of said hub and second axial projection means at a second surface of said hub opposite said first surface, a first wall which has a first opening for loosely receiving therein said first projection means of said central hub of said type wheel, a second wall which is integral with but is spaced by a predetermined distance from said first wall, wherein said second wall has a second opening for loosely receiving therein said second projection means of said central hub of said type wheel;
• and wherein said type wheel is housed in said cassette for rotary movement with respect thereto and said predetermined distance is such that at least one of said first projection means and first opening and said second projection means and second opening engage each other to limit radial movement of the type wheel with respect to the cassette, and wherein said cassette is free of spring means acting on the type wheel;
• and
• said biasing means of the printing machine urges one of said projection means of the type wheel in said axial direction when said cassette is in a printing position.

A printing machine comprising:

• a cassette-type wheel unit comprising:
• a cassette having a front wall provided with an opening, a rear wall, and a side wall connecting peripheral portions of the front and rear walls and spacing the front and rear walls from each other to leave interior space therebetween;
• and
• a type wheel rotatably housed in said interior space of the cassette and having a central hub provided with a front projection means which loosely fits in said opening in the front wall of the cassette to thereby allow free rotation of the type wheel in the cassette but to allow only limited radial motion of the type wheel relative to the cassette and thereby to resist removal of the type wheel from the cassette;
• wherein the rear wall includes an opening aligned with that in the front wall and the type wheel hub has a rear projection means which loosely fits in said opening in the rear wall;
• and
• wherein said cassette is free of spring means and the axial distance between the axial extremes of said front and rear projection means is at least as great as the axial dimension of said interior space at said openings;
• and
• a biasing means mounted in the printing machine and urging the front projection means of the type wheel rearwardly.

A printing machine comprising:

• a platen roller;
• a cassette for housing therein a type wheel having a central hub with a front projection means;
• means for detachably mounting the cassette in said printing machine and for permitting movement of the cassette between a printing position and a retracted position;
• biasing means engaging and urging rearwardly said front projection means of the type wheel hub when the cassette is in said printing position;
• said cassette comprising a rear wall having a first defined shape and provided with a printing window at its top portion and with a hub engaging opening, a front wall connected to said rear wall at least partly at its side to thereby form an integrated structure together with said rear wall and an internal space for housing therein said type wheel such that said type wheel is free to rotate within said cassette when the cassette is not mounted in said printing machine, said front wall having a second defined shape such that it is shorter in vertical height than said rear wall, to thereby expose a top portion of said rear wall;
• wherein said front wall also has a hub engaging opening loosely receiving said front projection means of the hub of the type wheel for rotation and for axial movement therein, said hub further having a rear projection means which is loosely receivable within said hub engaging opening of said rear wall for rotation and for axial movement therein, and wherein the axial distance between said front and rear walls relative to the axial distance between said front and rear projection means at said hub engaging openings is such that at any one time an engagement between at least one of said projection means and at least one of said hub engaging openings limits radial movement of the type wheel relative the cassette;
• and
• guiding means fixedly provided on said exposed top portion of said rear wall, said guiding means being engageable with an ink ribbon when said cassette is set in position for printing operation to help prevent said ink ribbon from being detained by said type wheel.

A printing machine comprising:

• a biasing means;
• a cassette housing therein a rotary type wheel having a hub with front and rear axial projection means;
• means for detachably mounting said cassette for movement relative to said biasing means between a printing position and a retracted position;
• said biasing means engaging and urging rearwardly said front projection means when the cassette is in said printing position;
• wherein said cassette comprises:
• a rear wall having a first defined shape and provided with a printing window at its top portion and with a hub receiving opening shaped to receive loosely said rear axial projection means of said hub;
• and
• a front wall connected to said rear wall at least partly at its side to thereby form an integrated structure together with said rear wall and an internal space for housing therein said type wheel, said front wall having a second defined shape and being provided with a hub receiving opening shaped to receive loosely said front projection means of said hub;
• and
• wherein said type wheel loosely fits in said cassette and is free to rotate therein when said cassette is not mounted in a printer, and the axial distance between said front and rear walls at said hub receiving openings relative to the axial distance between said front and rear projection means is such that the radial movement of said type wheel relative to said cassette is limited at all times by the engagement of at least one of said front and rear projection means with a respective hub engaging opening.

A printing machine comprising:

• a platen roller having a rotational axis;
• biasing means mounted at a fixed position relative to the rotational axis of the platen roller;
• a holder mounted in the printing machine to move between a forward, printing position and a rearward, retracted position such that in the printing position at least a portion of said holder is closer to the platen roller than in the retracted position;
• a cassette detachably mountable in said holder to move therewith between said printing and retracted positions, said cassette housing a type wheel which has a central hub having a front projection means and a rear projection means and said cassette having openings for loosely receiving said projection means;
• wherein said biasing means engages and urges rearwardly said front projection means of the type wheel hub when said holder and cassette are in said printing position.