Serial printer with a single type wheel

A serial printer, comprising:

• a fixed frame;
• a rocking frame having a base end portion pivotally supported by one end of the fixed frame and rockable relatively to the fixed frame between a first position, in which a sheet passage for a printing sheet, defined between the fixed and rocking frames is opened to allow the printing sheet to be inserted freely thereinto, and a second position, in which said sheet passage is closed, said rocking frame having a free end portion corresponding to the other end portion of the fixed frame, said rocking frame being further rockable from the second position to a third position on the opposite side thereof to the first position, said sheet passage being closed in the third position;
• a sheet holding mechanism for applying a holding force to the printing sheet in the sheet passage as the rocking frame rocks from the first position to the second and third positions;
• a single drive motor provided on the base end portion of the rocking frame;
• a single type wheel rotatably supported on the free end portion of the rocking frame and having its axis of rotation fixed with respect to the rocking frame;
• rotary drive transmission means disposed on the rocking frame and transmitting the rotatory force of the drive motor to the type wheel, thereby rotating the type wheel, said transmission means including a main rotating member having at least three separate rotational angular ranges, including first, second, and third ranges, within an entire 360 degree rotation thereof;
• said main rotating member including a main shaft rotatably supported by the rocking frame, and a single main cam rotatable in one with the main shaft and actuatable on said rocking frame to cause the rocking frame to rock from said first portion, said main shaft and said main cam being disposed on the rocking frame so as to be situated between the drive motor and the type wheel;
• a type selection mechanism for performing type selection on the type wheel in cooperation with the main rotating member while said rotating member is rotating through the first rotational range;
• a printing mechanism for performing printing operation by means of the type wheel following further rocking movement of the rocking frame by the action of said main cam from the second position to the third position, while said main rotating member is rotating through the second rotational angular range next to the first rotational angular range;
• and
• a sheet feed mechanism for performing sheet feed operation to feed the printing sheet in the sheet passage along a print line, in cooperation with the main rotating member, while said main rotating member is rotating through the third rotational angular range next to the second rotational angular range.

A serial printer, comprising:

• a fixed frame;
• a rocking frame supported by the fixed frame and rockable relatively to the fixed frame between a first position, in which a sheet passage for a printing sheet, defined between the fixed and rocking frames, is opened to allow the printing sheet to be inserted freely thereinto, and a second position, in which said sheet passage is closed, said rocking frame being further rockable from the second position to a third position on the opposite side thereof to the first position, said sheet passage being closed in the third position;
• a sheet holding mechanism for applying a holding force to the printing sheet in the sheet passage as the rocking frame rocks from the first position to the second and third positions;
• a single drive motor;
• a single type wheel rotatably supported by the rocking frame and having its axis of rotation fixed with respect to the rocking frame;
• rotary drive transmission means disposed on the rocking frame and transmitting the rotary force of the drive motor to the type wheel, thereby rotating the type wheel, said transmission means including a main rotating member having at least three separate rotational angular ranges, including first, second, and third ranges, with an entire 360 degree rotation thereof;
• a type selection mechanism for performing type selection on the type wheel in cooperation with the main rotating member while said rotating member is rotating through the first rotational range;
• a printing mechanism for performing printing operation by means of the type wheel by rocking, in cooperation with the main rotating member, the rocking frame from the second position to the third position while said main rotating member is rotating through the second rotational angular range next to the first rotational angular range;
• a sheet feed mechanism for performing sheet feed operation to feed the printing sheet in the sheet passage along a print line, in cooperation with the main rotating member, while said main rotating member is rotating through the third rotational angular range next to the second rotational angular range;
• and
• said sheet holding mechanism including sheet holding roller means adapted to be kept disengaged from the sheet in the sheet passage when the rocking frame is in the first position, and to engage and hold down the sheet when the rocking frame is in one of the second position and the third position;
• a position setting member attached to one of the fixed and rocking frames so as to be situated between the frames, and shiftable between first and second shift positions;
• a retaining member attached to the other of the fixed and rocking frames, and adapted in cooperation with the position setting member, to allow the rocking frame to rock to the first position when the setting member is in the first shift position, and to hold the rocking frame in the second position when the setting member is in the second shift position;
• first urging means for urging the position setting member toward the second shift position;
• and second urging means adapted to urge the position setting member, against the urging force of the first urging means, toward the first shift position when a specific type of the type wheel is situated in a printing position, whereby the printing sheet is kept subjected to an urging force from the sheet holding mechanism until the specific type of the type wheel reaches the printing position, during the sheet feed operation by the sheet feed mechanism.

A serial printer, comprising:

• a fixed frame;
• a rocking frame supported by the fixed frame and rockable relatively to the fixed frame between a first position, in which a sheet passage for a printing sheet, defined between the fixed and rocking frames, is opened to allow the printing sheet to be inserted freely thereinto, and a second position, in which said sheet passage is closed, said rocking frame being further rockable from the second position to a third position on the opposite side thereof to the first position, said sheet passage being closed in the third position;
• a sheet holding mechanism for applying a holding force to the printing sheet in the sheet passage as the rocking frame rocks from the first position to the second and third positions;
• a single drive motor;
• a single type wheel rotatably supported by the rocking frame and having its axis of rotation fixed with respect to the rocking frame;
• rotary drive transmission means disposed on the rocking frame and transmitting the rotatory force of the drive motor to the type wheel, thereby rotating the type wheel, said transmission means including a main rotating member having at least three separate rotational angular ranges, including first, second, and third ranges, within an entire 360 degree rotation thereof.
• a type selection mechanism for performing type selection on the type wheel in cooperation with the main rotating member while said rotating member is rotating through the first rotational range;
• a printing mechanism for performing printing operation in a printing position by means of the type wheel by rocking, in cooperation with the main rotating member, the rocking frame from the second position to the third position, while said main rotating member is rotating through the second rotational angular range next to the first rotational angular range;
• a sheet feed mechanism for performing sheet feed operation to feed the printing sheet in the sheet passage along a print line, in cooperation with the main rotating member, while said main rotating member is rotating through the third rotational angular range next to the second rotational angular range;
• said sheet feed mechanism including sheet feed drive means engaging the main rotating member, thereby producing a fixed operation stroke corresponding to a predetermined sheet feed pitch, said drive means having a sheet feed control member movable between an adjustment position in which the control member adjusts the fixed operation stroke, thereby changing the sheet feed pitch, and a nonadjustment position in which the control member allows the operation stroke;
• restriction means capable of engaging the sheet feed control member so as to restrict the control member to the adjustment position;
• and a type detection member adapted to shift its position corresponding to a specific type of the type wheel and cause the control member to engage the restriction type of the type wheel and cause the control member to engage the restriction means when the specific type is situated in the printing position, whereby the printing sheet is fed with the adjusted pitch along the print line, with the specific type in the printing position;
• and
• said type detection member cooperating with a cam member rotatable in one with the type wheel and having a recess formed at a rotational position corresponding to the specific position, and having a projection adapted to engage the recess of the cam member, thereby shifting the position of the type detection member, when the projection corresponds in position to the recess.

A serial printer, comprising:

• a fixed frame;
• a rocking frame supported by the fixed frame and rockable relatively to the fixed frame between a first position, in which a sheet passage for a printing sheet, defined between the fixed and rocking frames, is opened to allow the printing sheet to be inserted freely thereinto, and a second position, in which said sheet passage is closed, said rocking frame being further rockable from the second position to a third position on the opposite side thereof to the first position, said sheet passage being closed in the third position;
• a sheet holding mechanism for applying a holding force to the printing sheet in the sheet passage as the rocking frame rocks from the first position to the second and third positions;
• a drive motor;
• a type wheel rotatably supported on the rocking frame and having its axis of rotation fixed with respect to the rocking frame, said type wheel having a plurality of types thereon, which include a specific type;
• a rotary drive transmission mechanism disposed on the rocking frame and transmitting the rotatory force of the drive motor to the type wheel, thereby rotating the type wheel, said transmission mechanism including main rotating means having at least three separate rotational angular ranges, including first, second, and third ranges, within an entire 360 degree rotation thereof;
• a type selection mechanism for performing type selection in cooperation with the main rotating means to select and set one type of the type wheel to a printing position while said rotating means is rotating through the first rotational range;
• a printing mechanism for performing printing operation to print said selected type;
• on the printing sheet held in the sheet passage by rocking, in cooperation with the main rotating means, the rocking frame with the type wheel from the second position to the third position, while said main rotating means is rotating through the second rotational angular range next to the first rotational angular range;
• a sheet feed mechanism for performing sheet feed operation to feed the printing sheet in the sheet passage along a print line, in cooperation with the main rotating means, while said main rotating means is rotating through the third rotational angular range next to the second rotational angular range, said sheet feed mechanism including:
• sheet feed drive means engaged with and driven by the main rotating means, thereby producing a given operation stroke corresponding to a predetermined sheet feed pitch, said drive means having a sheet feed control member movable between an adjustment position in which the control member adjusts the given operation stroke, thereby changing the sheet feed pitch, and a nonadjustment position in which the control member allows the given operation stroke;
• restriction means driven by said main rotating means and capable of engaging the sheet feed control member so as to move the control member to the adjustment position;
• type detection means operatively connected to said sheet feed control member and able to take a detecting position in which said detection means urges the sheet feed control member to engage with the restriction means in response to said type detection means detecting said specific type on the type wheel being situated in the printing position;
• and
• holding means for holding the sheet feed control means so as to be engaged with the restriction means even after said type detection means leaves said detecting position.