Ink Ribbon Cartridge Including a Movable Ribbon Tensioning Guide for a Printing Machine

The present invention relates to an ink ribbon cartridge for a printing machine in particular for a needle printing head fitted on to a movable carriage parallel to the proper guide roll and in which the head can be moved on the carriage perpendicular to its direction of movement.

A machine of the type described is known, in particular for printing on to bank books, in which the ribbon which is wound on to independent spools has a length guided by two ribbon guides arranged at the sides of the paper guide roll, parallel to the roll. The head is fitted with two lateral guides which bring that part of the ribbon placed opposite the typing area close to the roll. The printing head is, moreover, movable on the carriage perpendicular to the roll so as to follow the variations in thickness of the books by keeping constant the distance between the needles, the ribbon and the printing area in every position of the carriage along the line of typing. At each typing cycle, the needles bend the ribbon to maintain a spacing from the printing surface which is independent of the thickness of the book. During the movement of the head in relation to the carriage, the feed mechanism of the ribbon takes care of the ribbon which has to be paid out and that which has to be taken up as the head advances and retracts by keeping the ribbon subjected to a substantially constant tension. While being satisfactory, this solution is, however, somewhat expensive and also results in complications connected with the replacement of the ribbon wound on to independent spools.

A needle printer is also known which uses an ink ribbon cartridge fitted on to the carriage so as to guide a length of ribbon adjacent to the needles of the head in proximity to the paper guide roll. The printing head is fixed on to the carriage and the ribbon is fed by a single direction feed mechanism which is carried on the carriage which, by means of a pair of wires and pulleys is set in motion when the carriage is moved along the line of typing. This solution, which is economic and easy to use cannot, however, be used in printers with movable heads on the carriage, since the ribbon feed mechanism does not permit recovery of the ribbon which has been paid out and, if the carriage were to follow the movement of the head, this latter would require a specific feed mechanism to follow the movement of the cartridge support, thus increasing the mass of the moving parts and the overall cost of the machine.

The object of the invention is to provide an ink ribbon cartridge which is simple, of a relatively modest cost and which can be used in a needle printer in which the head can move in relation to the carriage.

According to the present invention there is provided an ink ribbon cartridge for a printer of the type which includes a carriage which supports the cartridge and moves in a direction parallel to the line of typing and a needle printing head, which can move on the carriage perpendicular to its direction of movement, to advance and retract the head with respect to that on which printing is effected, the cartridge comprising a ribbon housed in a container having two guides between which passes an external length of ribbon for engagement with the head, and a movable tensioning guide which engages the ribbon and is movable in a first direction to pay out ribbon to the external length as the head is advanced and is movable in a second, opposite direction to take up slack from the external length as the head is retracted.

In use, the movable guide is coupled to the head so that the necessary movements of the guide take place automatically as the head moves on the carriage, keeping the external length of ribbon under constant tension.

The invention will be described in more detail, by way of example, with reference to the accompanying drawing, in which:

FIG. 1 is a partial plan view of a cartridge embodying the invention,

FIG. 2 is a partial plan view of a printer on to which the cartridge in FIG. 1 is fitted,

FIG. 3 is a partial plan view of the machine in FIG. 2 in the working position,

FIG. 4 is a partial section on the line 4--4 in FIG. 2, and

FIG. 5 is a partial plan view of the machine in FIG. 2.

With reference to FIG. 1, a cartridge 11 for an ink ribbon 38 includes a container 12 of plastics material. The container 12 consists of a base 13 and of a series of inner walls 14, 16 and 17 which bound an opening 18 to house a needle printing head 19 (FIG. 2) which is carried by a carriage 43 of a printer 44. The walls 14 (FIG. 1) and 17 are joined together at the top by a cross piece 21 which strengthens the container walls 14 and 17 and forms them into a single unit. The container 12 is closed at the top by a cover 22, by a rear wall 23, by a front wall 24 and by side walls 26, 27, 28 and 29.

The cartridge 11 includes, projecting from the rear wall 23, two arms 31 and 32 which are closed at the top by a plate 33 (FIG. 2) of the cover 22, which are inclined outwardly and which have, at the ends, two openings 36 (FIG. 1) and 37 respectively to allow passage and to guide out a portion of the ink ribbon 38. The arms 31 and 32 are arranged at an angle in relation to the ends of the printing head 19 (FIG. 2) so that the external portion of ribbon 38 is the minimum. A second plate 39 of the cover 22 forms with the plate 33 a seat 41 for the cross piece 21.

The cartridge 11 is held fixed to the carriage 43 by means of three pins 42 on the carriage 43 so that each pin 42 is gripped by two flexible blades 46 bent up from the base 13 of the container 12.

A series of internal walls 47 (FIG. 1) 48 and 49 form the boundaries of a magazine 52, in which the ribbon 38 is arranged in loose folds. The magazine 52 is arranged on the side opposite to the openings 36 and 37 and is fitted with an outlet area formed by an opening or corridor 53 bounded by the walls 27 and 48 for the outlet of the ribbon 38, and with an entry area bounded by a pair of rollers 67 for the single directional feed of the ribbon 38. The space available for the ribbon 38 increases progressively along its length from the area of the rollers 67 to the outlet area 53. Furthermore, the base 13 and the cover 22 include respectively a series of ribs 109 and 111, which project towards the inside of the container 12, to reduce the density of the ribbon 38 as it is being transported to the area 53.

The walls 17, 23, 26 and 27 form a first corridor 54 in which the ribbon 38 is guided from the outlet area 53 by means of guides 56, 57, 58 and 59 to the opening 36. The walls 14, 23 and 29 form a second corridor 61 which is wider than the first and in which the ribbon 38 is guided from the opening 37 to the pair of rollers 67, by means of guides 62, 63 and 64 and a tensioning unit 66 which forms on the ribbon 38 a loop between the opening 37 and the guide 63. The magazine 52 and the two corridors 54 and 61 surround the printing head 19 completely (FIG. 2).

The printer 44 (FIG. 5) includes a usual paper platen 72 on which there normally rests a document 73 of a variable thickness along the platen 72. The carriage 43 can be moved transversely to the document 73 along guides 74 and 76 and by means of sleeves 77, rollers 78 and counterrollers 79, in a known manner. The head 19 in turn is fixed on to a support 71 which is movable perpendicularly to the document 73 by means of a guide 81 and a tongue 83 which move smoothly in two sockets 82 and a slot 84 on the carriage 43, respectively. A roller 86 revolves on the support 71 and can rest against the document 73 to keep constant the distance between the end of the head 19 which bears the needles and the typing area of the document 73. The support 71 has two downwardly projecting pins 87 (FIG. 4) which straddle a universal bar 88 which turns about a shaft 89 parallel to the platen 72. The bar 88 is as long as the platen 72 and pushes the support 71 towards the document 73 under the action of a spring 91. A lever 92, controlled manually for example, holds the support 71 at a distance of approximately 8 mm from the platen 72 in order to facilitate the introduction and the reading of the document 73. When the lever 92 is released, the spring 91 turns the universal bar 88 in an anti-clockwise direction, (in FIG. 4), bringing the roller 86 against the document 73 as shown in broken lines in FIG. 4 to bring the end of the head 19 to a distance of approximately 0.7 mm from the document 73. The roller 86 and the bar 88 then keep this distance constant during the movement of the carriage 43, following the variations in the thickness of the document 73.

The pair of rollers 67 in the cartridge 11 (FIG. 1) are able to engage with a feed device 96 fitted on to the carriage 43 (FIG. 4), and as described in U.S. patent application Ser. No. 863,420 of Bernardis et al., filed on Dec. 22, 1977. The pair of rollers 67 (FIG. 1) includes a driving roller 97 and a pressure roller 98, each fitted with a hollow sleeve 104 which is able to be engaged by a driving pin 99 (FIG. 2) and by a pressure pin 101 on the feed device 96, respectively. The driving roller 97 and the pressure roller 98 are free to move radially in corresponding seats 102 and 103 in the base 13 and the cover 22 respectively in order to facilitate the engaging of the sleeves 104 with the pins 99 and 101 during the fitting of the cartridge 11.

In particular, the driving pin 99 (FIG. 4) is, by means of a pair of gears 112 and 113 which revolve on the carriage 43 and a free wheel device already known such as the one-way clutch 29 shown in FIG. 2 of Bittner U.S. Pat. No. 3,939,957, turned in one direction by two pulleys 116 and 117. For this purpose, two wires 118 and 119 are stretched parallel to the platen 72 and each is wound on to its respective pulley 116 and 117 in a direction opposite to one another. Following a movement of the cartridge 43, the two wires 118 and 119 make the respective pulleys 116 and 117 turn in opposite directions; from movement in a first direction, one pulley 116 or 117 transmits movement to the pin 99 while the other pulley 117 or 116 remains idle; when the opposite occurs, when movement takes place in the opposite direction, the roles reverse between the pulleys 116,117 so that the pin 99 always turns in the same direction. The pressure pin 101 (FIG. 5) is, in its turn, fixed on to a bellcrank 121 which is supported on a pin 122 in the carriage 43, while a spring 123 normally holds the pin 101 at rest against a side of the carriage 43.

The tensioning unit 66 in the cartridge 11 (FIG. 1) includes a roller borne by a coupling 126 having two ends housed and guided in corresponding slots 127 of the base 13 and of the cover 22. The slots 127 are substantially parallel to the direction of movement of the head 19 in relation to the carriage 43 (FIG. 2). The coupling 126 of the roller 66 is able to house a corresponding stud or dragging element 129 (FIG. 4) of the support 71 and is free to move with play in the slots 127. Furthermore, a flexible tongue 131, formed by a piece of the cover 22, is fitted into the corresponding slot 127 and is able to engage with the upper end of the coupling 126 to hold the roller 66 in a position of rest with a maximum loop of the ribbon 38, when the cartridge 11 is removed from the machine 44. This makes it possible to align the stud 129 of the head 19 with the coupling 126 during the fitting of the cartridge 11 on to the machine 44 when the head 19 is at a distance from the platen 72.

For the purposes of fitting, the cartridge 11 (FIG. 2) is placed at an angle with the ribbon 38 emerging from the arms 31 (FIG. 1) and 32 being arranged on the leading edge of the head 19 (FIG. 2): the pins 42 are then engaged between the flexible blades 46 and the stud 129 (FIG. 4) enters the seat 128. A slight pressure is exercised on the cover 22, with the cartridge 11 being lowered towards the carriage 43. During this operation, the pins 99 and 101 positioned as in FIG. 5, engage the sleeves 104; the pressure roller 98 then moves the pressure pin 101 away from the driving pin 99. The spring 123 pushes the bellcrank 121 in a clockwise direction and the pressure pin 101 brings the pressure roller 98 closer to the drive roller 97, to leave a length of the ribbon 38 nipped between the rollers 97 and 98. An opening 132 in the cartridge 11 (FIG. 1) makes it possible to rotate the pressure roller 98 manually to tension the ribbon 38 if it has slackened.

The working of the tensioning unit 66 in the cartridge 11 (FIG. 4) is as follows. Once the lever 92 is released, the spring 91 turns the universal bar 88 in an anti-clockwise direction; by means of the pins 87, this latter makes the support 71 with the head 19 move backwards (towards the left in FIG. 4), bringing the roller 86 to rest against the document 73 fixed in the position shown by broken lines.

During this movement, the head 19 with its end moves back the portion of ribbon 38 which normally rests against the head 19 itself and, at the same time, with the stud 129, makes the roller 66 in the slots 127 slip towards the paper platen 72. The movement of the head 19 with the ribbon 38 is identical to the stroke of the roller 66; consequently, there is no movement of the ribbon 38 in the corridor 61 but only a reduction in the loop in the element 66 in relation to the original position. If a part of the document 73 of considerable thickness is met with during the feed of carriage 43, the roller 86 moves forward the support 71 with head 19 (towards the right in FIG. 4) to return to the position of rest. Under the action of the tensioning unit 66, the ribbon 38 slips forward at the same time as the head 19 and remains tensioned and at the working distance from the document 73, thereby avoiding any risk of slackening or of undesirable contact with the document 73. The same thing happens when, at the end of the typing, the lever 92 is worked to bring the head 19 to its position of rest at the maximum distance from the roll 72.

It is, therefore, obvious that the tensioning unit 66 of the ribbon 38 keeps the ribbon 38 constantly tense in any position of the head 19 in relation to the carriage 43.