Printer with driving mechanism by single motor for both sheet transferring mechanism and sheet cutting mechanism

Abstract: There is provided a printer (1) capable of eliminating overlapped members in a driving system to reduce its cost and at the same time capable of attaining a small-sized printer itself. A single driving motor selectively drives a sheet transferring mechanism and a sheet cutting mechanism of a printer comprised of the sheet transferring mechanism having a platen roller (2) and a roller driving gear (6) arranged at a rotating shaft of the platen roller; a printing mechanism for performing a recording on a sheet transferred by the platen roller; and the sheet cutting mechanism provided with each of a fixed blade fixed and arranged at the printer, a moveable member (12) having a movable blade (11) which can shear the sheet present between it and the fixed blade while sliding at one surface of the fixed blade and moving means for sliding the movable member in a direction of surface of the fixed blade.

Description: This invention relates to a printer having a sheet cutting mechanism for cutting a printed portion of a sheet fed out of a sheet roll to an appropriate length after performing a desired printing of the sheet. A printer in which a sheet fed out of a sheet roll is pulled around a sheet transferring path within the printer and the sheet is cut into a requisite length after a desired printing is applied to the sheet at a recording section of the printer has been widely used as a printer for use in printing a receipt which is issued as a receipt to a purchaser and the like or a receipt journal printer in which printings for two kinds of sheets of the receipt and a journal stored as a bill for a commodity management or the like at a supplier can be carried out once. As a mechanism for cutting the sheet in these printers (hereinafter called as a sheet cutting mechanism), it may be considered as a simple configuration to provide a system in which a long side of an opening part of the case in a printer serving as a transferring path for the printed sheet, for example, is formed with some saw-teeth shaped cutting protrusions and the sheet is cut off while the sheet is being pushed against the cutting protrusions from its end part in a width direction. However, in accordance with the sheet cutting mechanism having this configuration, there occurred a possibility that the sheet was not always cut off in its well-appearance and the sheet portions used as a receipt or the like were damaged depending upon a manner of cutting performed by a user. In view of the foregoing, it has been developed to provide a printer in which a sheet cutting mechanism for mechanically cutting the sheet after printing under driving of the cutting mechanism with a driving means is installed as a separate unit. However, since another driving means was required in addition to the driving means for the printer, the sheet cutting mechanism had double members for constituting the driving means such as a motor or the like, resulting in that the mechanism had some disadvantages that it needed additional cost and an entire size of the printer having the sheet cutting mechanism installed therein was made large. This problem may be solved by providing a single drive motor as disclosed in US 5 671 065. This invention has been invented in reference to the aforesaid fact and it is an object of the present invention to provide a printer in which a dual application of the driving members is reduced and at the same time its cost is also decreased and further a small-sized formation of the printer itself can be realized. This object is achieved with the printer as defined by the appended claims. In accordance with the present invention, employment of such a configuration as above enables the single motor to be used for both mechanisms, the sheet transferring mechanism to be driven when the sheet is transferred and the sheet cutting mechanism to be driven after the sheet is transferred. In accordance with the present invention, the engaged state of the gears can be changed over by oscillating the oscillation arm in response to the rotating direction of the transmission motor while the sheet transferring mechanism and the sheet cutting mechanism are being applied as a common driving source. Embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is an illustrative view for showing a substantial part in a sheet transferring mechanism of a printer of the preferred embodiment of the present invention. Fig. 2 is an illustrative view for showing a substantial part in a sheet cutting mechanism of a printer of the preferred embodiment of the present invention. Fig. 3 is an illustrative view for showing an engaged state of gears when the driving motor in the printer in Fig. 1 is rotated in a normal direction. Fig. 4 is an illustrative view for showing an engaged state of gears when the driving motor in the printer in Fig. 2 is rotated in a reverse direction. Referring now to Figs. 1 to 4, the preferred embodiment of the present invention will be described as follows. As a printer 1 shown in Fig. 1, a substantial portion of the printer 1 of the preferred embodiment of the present invention is illustrated, wherein a platen roller 2 for use in performing a printing operation against a sheet supplied is suspended at opposing two frames 1A of a casing of the printer 1 in such a way that it can be rotationally driven. Near the platen roller 2 is installed a thermal head 3 having a plurality of heat generating elements arranged in rows in a straight line form to be oppositely faced against the central part of the platen roller 2 and moved to or away from an entire width of the platen roller 2 in such a way that the thermal head 3 can be oscillated. Then, the end part of the sheet is pulled out of the sheet roll held at the sheet supplying section (not shown) , the sheet is drawn around the sheet transferring path within the printer 1, the sheet is supplied between the platen roller 2 and the thermal head 3 acting as the printing section so as to cause a desired printing to be carried out. In a preferred embodiment, the platen roller 2 may constitute one member of the sheet transferring mechanism and a normal rotation driving force of the driving motor 5 acting as a sheet transferring driving source is transmitted from the motor gear 6 formed at the rotating shaft 5A of the driving motor 5 through transmission gears 7, 8 and the oscillation gear 21 against the roller driving gear 4 formed coaxially with the platen roller 2, thereby the platen roller 2 is rotated and the sheet transferring around the platen roller 2 is performed. The aforesaid driving force transmission mechanism (hereinafter called as a driving transmission mechanism) will be described as follows. In addition, the sheet cutting mechanism is integrally formed in the printer of the preferred embodiment of the present invention. This sheet cutting mechanism is installed at a downstream side of the printing section in the sheet transferring path of the printer 1 and this sheet cutting mechanism in the preferred embodiment of the present invention is the casing portion corresponding to the installed position of the platen roller 2 and is installed at a sheet discharging port for use in discharging the sheet, after its printing, out of the casing. As shown in Fig. 2, the sheet cutting mechanism is comprised of a fixed blade 10 fixed and arranged at the printer 1; a movable member 12 having a movable blade 11 oscillated against the fixed blade 10 and slidingly contacted with the fixed blade 10 in its surface direction to enable the sheet present between the fixed blade and the movable blade to be sheared; and a moving means capable of moving the movable member 12 in the surface direction of the fixed blade 10, and further the moving means is comprised of a spring member 14 for applying a specified tension against the movable member 12 in a surface direction of the fixed blade 10; a cam gear 17 having a pin 16 engaged in a slide hole 15 formed at a base part 12A of the movable member 12; and a plurality of transmission gears 18 for transmitting a driving force to the cam gear 17. As shown in Fig. 2, the fixed blade 10 of the sheet cutting mechanism has substantially the same length as that of the platen roller 2 of the printer 1 and is fixed and arranged at the casing of the printer 1 in such a way as that the fixed blade 10 is in parallel with the platen roller 2 and its blade edge is positioned in a linear straight manner with its blade edge being faced toward the sheet transferring path. One movable blade 11 is arranged at a side of the plate-like movable member 12 where it is directed toward an arranging direction of the fixed blade 10 and in the preferred embodiment of the present invention, the central part of the movable blade 11 at its extending direction is formed like a dogleg shape where it is spaced apart from the arranging direction of the fixed blade 10. The movable member 12 is formed into a substantial Y-shape in its entire shape and its side opposite to the forming of the movable blade 11, i.e. the side spaced apart from the sheet transferring path is applied as a base section 12A. And then, the spring member 14 constituting the moving means for supporting the central part of the movable member 12 in its longitudinal direction (the extending direction of the fixed blade 10) at the casing of the printer 1 and the one side (the lower side as viewed in the figure) of the engaging position of the spring member 14 of the base section 12A is formed with a long-groove shaped slide hole 15 extending in an arranging direction of the fixed blade 10. Then, the slide hole 15 is engaged with a pin 16 formed on the upper surface of the cam gear 17 arranged at the rear surface side of the movable member 12. Then, the cam gear 17 is installed at the most downstream side within the sheet cutting mechanism and the driving force generated when the driving motor 6 acting as a driving source for transferring sheet of the printer 1 is rotated in a reverse direction is transmitted to the cam gear 17 through a plurality of transmission gears 18 including a helical gear in order from the cutter driving gear 19 installed at the most upstream side in the sheet cutting mechanism. Referring now to Figs. 3 and 4, the driving transmission mechanism will be described as follows. A motor gear 6 is arranged at the output shaft 5A of the driving motor 5 and a transmission gear 7 for use in transferring the driving force of the driving motor 5 to either the sheet transferring mechanism or the sheet cutting mechanism is engaged with the motor gear 6. At the rotating shaft 7A of the transmission gear 7 is arranged the oscillation arm 20 oscillated to enable the driving force to be transmitted to the gears 4, 19 positioned at the downstream side in a transmitting direction through the normal or reverse rotation of the driving motor 5. Two oscillation gears 21, 22 having small diameter and large diameter, respectively, are formed coaxially at the extremity end of the oscillation arm 20, wherein the oscillation gear 22 having the large diameter is engaged with the transmission gear 8 having the small diameter which is coaxially arranged with the transmission gear 7, and the driving force of the driving motor 5 is transmitted to cause the oscillation gears 21, 22 coaxially supported to each other to be rotated. In a preferred embodiment, the oscillation gear 21 having the small diameter is engaged with the roller driving gear 4 formed at the platen roller 2 under an oscillation of the oscillation arm 20 as the rotating shaft 7A of the transmission gear 7 is rotated when the driving motor 5 is rotated in a normal direction as shown in Fig. 3, resulting in that the driving force can be transmitted only to the sheet transferring mechanism. In turn, the oscillation gear 22 having large diameter is engaged with the cutter driving gear 19 arranged at the uppermost upstream side of the sheet cutting mechanism by a method wherein the oscillation arm is oscillated through rotation of the rotating shaft 7A of the transmission gear 7 when the driving motor 5 is rotated in a reverse direction as shown in Fig. 4 and then the driving force can be transmitted only to the sheet cutting mechanism. Then, an action of the preferred embodiment of the present invention will be described as follows. The sheet transferring mechanism and the sheet cutting mechanism can be driven by the same driving means as described above. That is, the sheet in the printer is fed out of the sheet roll through driving of the sheet transferring mechanism, applied to have a desired printing at the printing section, thereafter the printed sheet is discharged out of the casing through the sheet discharging port and cut. At this time, in the case that the sheet is transferred during the printing and the like, the driving motor 5 is driven to rotate in a normal direction, the oscillation gear 21 is engaged with the roller driving gear 4 and its driving force is transmitted only to the sheet transferring mechanism. That is, at this time, since the oscillation gear 22 is not engaged with the cutter driving gear 19, the sheet cutting mechanism is not driven. Then, upon completion of the predetermined printing, the sheet of appropriate length is transferred to cause the printed sheet portion to be discharged out of the printer 1 and thereafter the driving motor 5 is driven to rotate in a reverse direction. The oscillation arm 20 is oscillated under a reverse driving operation of the driving motor 5, the oscillation gear 22 is engaged with the cutter driving gear 19 of the sheet cutting mechanism to cause its driving force to be transmitted only to the sheet cutting mechanism. In this way, the driving force of the driving motor 5 transmitted to the cutter driving gear 19 is transmitted up to the cam gear 17 through the transmission gears 18 arranged with the sheet cutting mechanism. At the cam gear 17, when the cam gear is rotated under application of the driving force, the movable blade 11 is oscillated in a horizontal direction so as to perform a sliding contacted state in relation with the fixed blade 10 while the pin 16 formed at the upper surface of the cam gear 17 is being slid within the slide hole 15 of the movable member 12 and while resisting against a tension of the spring member 14. The sheet present between the fixed blade 10 and the movable blade 11 can be sheared under this oscillation performed in a horizontal direction. In addition, the present invention is not limited to the preferred embodiment as described above and various modifications of it can be carried out. The invention is defined by the appended claim. For example, the shape of the movable blade in the preferred embodiment is not formed into a dogleg shape, but it may be formed into a linear straight shape. In addition, although two kinds of gears of large diameter and small diameter are arranged as the oscillation gears in the preferred embodiment of the present invention, only one oscillation gear may also be applied. In addition, as a printer, the preferred embodiment has been described in reference to the thermal printer using the thermal head as the printing head, although it is of course apparent that an ink jet printer may also be applicable. As described above, in accordance with the present invention, there are provided some effects that both transferring of the sheet to be printed and cutting of the sheet after its printing can be carried out by driving a common driving source and then reduction in cost caused by decreasing the number of members and a small-sized formation of the printer itself can be attained.

Claims: A printer comprising: a sheet transferring mechanism having a platen roller (2) and a roller driving gear (4) arranged at a rotating shaft of the platen roller; a printing mechanism (3) for performing a recording on a sheet transferred by the platen roller; a sheet cutting mechanism provided with each of a fixed blade (10) fixed and arranged at the printer, a movable member having a movable blade (12) which can shear the sheet present between it and the fixed blade while sliding at one surface of the fixed blade, and moving means for sliding the movable member in a direction of surface of the fixed blade; a single motor (5) for selectively driving the sheet transferring mechanism and the sheet cutting mechanism; an oscillation arm (20) arranged at the rotating shaft (7a) of a transmitting gear engaged with a motor gear (6) arranged at the driving motor; the printer being characterized by an oscillation gear (21,22) arranged only at one end of the oscillation arm; and driving transmission means in which the driving motor is rotated in a normal direction or a reverse direction to cause the oscillation arm to be oscillated in the rotating direction of the oscillation arm and to cause the oscillation gear to be selectively engaged with one of the roller driving gear and a cutter driving gear (19) which is positioned at the upper-most stream side of the sheet cutting mechanism. A printer according to claim 1, wherein the oscillation gear is constructed such that two gears of different diameters are formed on the same shaft; one of the gears being engageable with the roller driving gear, and the other gear being engageable with the cutter driving gear.

Inventors: HORI FUMIHISA, MURAYAMA HIROYUKI, HORI, FUMIHISA, MURAYAMA, HIROYUKI
Applicants: ALPS ELECTRIC CO LTD, ALPS ELECTRIC CO., LTD.
Application year: 2000
Main classification: B41J11
IPC codes: B41J11, B41J23