A printing apparatus having an auto cutter

Abstract: A printing apparatus comprises a first cover (34), provided on a body frame (38) including a print head, for covering the print head; a second cover (39), disposed on the body frame opposing to the first cover through a transport path for transporting the recording medium, for mounting an auto cutter (36). The auto cutter (36) comprises: a cutter frame for fixing the auto cutter to the second cover (39); a cutter blade, movably supported on the cutter frame, for cutting the recording medium printed by the print head; and an auto cutter drive source (37), fixed on the cutter frame, for driving the cutter blade to cut the recording medium.

Description: The invention relates to a printer provided with an auto-cutter, installed in cash registers, etc. A printer provided with an auto cutter is disclosed in the document JP-U-118852/82. In this known printer, a head cover for protecting the print head is pivotally mounted on a base frame so that, when paper jamming occurs around the print head, the jammed paper can easily be removed by opening the head cover. An auto cutter unit including a drive source is installed on the head cover. In this prior art the auto cutter is installed on the operator's side of a receipt paper discharge port, making it difficult to extract the receipt or visually check its print quality. When the receipt discharge port is positioned in a high location matching the position of the auto cutter, the height of the overall printer increases, lengthening the distance the printed receipt paper must travel after having been printed and thus increasing both the time required for issuing a receipt and the amount of wasted recording paper. Further, if a journal printing mechanism is provided adjacent to the receipt printing mechanism, the receipt discharge port is placed in a protruding manner close to a writing platform used for correcting printing results on the journal paper, thus hindering the correction operation. Still further, since the auto cutter is a heat source, placing the auto cutter just above the print head affects cooling of the print head, thus lowering the printing speed and causing poor printing quality. US-A-4,279,039 discloses a thermal printer having first and second sub-frames pivotally supported on a main frame to provide access to a dot resistance thermal print head for cleaning and easy removal of the respective structures. Each structure is releasably fixed in operating position in which a resilient drive roller on the second sub-frame presses the thermally sensitive paper against the print head. The drive roller is driven by a motor on the second sub-frame and moves the paper along the paper path by friction drive. The paper moves between a fixed and rotatable knife on the second sub-frame actuated by crank and linkage connection to the core of a solenoid whose winding is fixed on the main frame. The paper guides disclosed therein are fixed to the same sub-frame rather than to two different units movable with respect to each other. The document IBM Technical Disclosure Bulletin, vol. 26, no. 7a, Dec. 1983, pp. 3333-3334 discloses a mechanism illustrated combining a variety of functions necessary in point-of-sale terminal printers for printing customer receipts and the like. A cut-off support bar 1 also used as a platen has a rectangular aperture through which journal paper is fed by means of rollers driven by some rotary power source. A print head of any suitable type traverses a print line back and forth so as to a print line on the paper. A cut-off bar has a plurality of serrated teeth and is reciprocated on eccentric, operating in the aperture, when the eccentric is rotated. The cut-off bar is guided by a sliding pair of guides penetrating slots in the cut-off bar, The eccentric is driven by a rotary solenoid or any other suitable rotational drive on demand. A printing apparatus is also disclosed in US-A-2,780,288. The printing apparatus has a structure similar to a typewriter which is electrically controlled and in which types mounted on respective type bars are struck against a strip of paper backed by a platen that is used as transport roller at the same time. The paper is drawn from a roll and, after having been printed, is fed to a ticket cutting, feeding and stacking mechanism mounted on the rear part of the typewriter's casing. The object of the present invention is to solve the above-mentioned problems, and to provide a printer that offers superior legibility of printed receipts, allows to quickly issue receipts after printing, wastes little recording paper, and offers high speed and high quality printing. This object is achieved with a printing apparatus as claimed in claim 1. Preferred embodiments of the invention are subject-matter of the dependent claims. According to the configuration of the invention, both the auto cutter mechanism and its drive source are provided on the pivotally mounted cover that covers the platen opposite to the print head. Thus, it becomes easy to check the printing results on the recording medium and it is facilitated to cool the print head by removing the auto cutter, a kind of a heat source, from right above the print head. Even if paper jamming has occurred about the printing head, it is easy to remove the jammed paper by opening the cover. A motor, the auto cutter drive source, can be installed utilizing a space below a writing platform, thus eliminating space for mounting the motor around an outlet for the first recording medium to be cut by the auto cutter and facilitating the device size reduction. According to an embodiment of the invention, the paper supply port which is an inlet for inserting the recording medium into the transport path can be positioned in an upper area, namely a position nearer to the operator. Consequently, paper can be inserted into paper supply port while visually checking the position of the inlet, significantly improving operability. In this case, when a transfer gear is positioned approximately at the center of the pivots of the cover, the distance between the transfer gear and the feed-out roller shaft rotatably fixed on the cover does not change, thus maintaining a nearly constant meshing relationship between the two elements while the cover pivots. The invention disclosed herein will be better understood with reference to the following drawings which illustrate specific embodiments of the invention only, and in which: Fig. 1 is a top view of a printer embodying the present invention, Fig. 2 is a side view from direction B in Fig. 1, Fig. 3 is a cross-sectional view along line C - C in Fig. 1, Fig. 4 is a rear perspective view of a printer embodying the present invention, Fig. 5 is an exploded perspective view of the auto cutter mechanism provided in a printer embodying the present invention, and Fig. 6 is an enlarged view of the cutter drive source that drives the auto cutter mechanism according to an embodiment of the present invention. Figs. 1 through 6 show a printer as an embodiment of the printing apparatus according to the present invention. Printer 35 of this embodiment is a dot impact printer to be installed in cash registers, etc. As shown in Figs. 1, 2 and 4, printer 35 comprises printer main unit 38 in which ribbon cassette 2 is detachably installed, and clamshell-like cover or movable part 39 that is rotatably supported in the upper rear part of printer main unit 38 to be pivotable between a closed position (shown in solid lines in Fig. 3) and an open position (shown in broken lines in Fig. 3). Printer main unit 38 is provided with a printing mechanism including print head 5 mounted on a carriage (not shown in the figures) which is movable back and forth in the lateral (width) direction of recording papers 7 and 8; a paper-feeding mechanism (not shown in the figures) for feeding recording papers 7 and 8 to a printing position of print head 5; and drive motor 11a which is the common drive source for said printing mechanism and paper-feeding mechanism. The printing mechanism is covered by cover 34. On the other hand, movable part 39 comprises platen 65, another paper-feeding mechanism consisting of paper feed roller 66 and paper pressing roller 67 for pressing recording paper onto said paper feed roller 66, auto cutter mechanism 36 for cutting receipt paper 8, which is installed in the upper area of the paper-feeding mechanism, and upper paper guide 62 made of resin, wherein upper paper guide 62 mounts the remaining elements listed above. Note that auto cutter mechanism 36 is configured as a unit to be easily detached when provided as an option. Movable part 39 is pivotally supported on printer main unit 38 by means of two pivots. These pivots define a pivot axis of movable part 39 and are formed by a respective protrusion or pivot shaft 23 on each side of upper paper guide 62 and a respective shaft receiving hole 23a provided in the frame of printer main unit 38. A locking mechanism is formed by a stopper (not shown in the figures) provided on upper paper guide 62 and a claw (not shown in the figures) provided in a rotatable manner in the printer main unit. Upper paper guide 62 is normally locked in the closed position of movable part 39 by said claw engaging said stopper, and is pivotable around the pivot axis by disengaging said claw from said stopper. As shown in Fig. 1, one of the protrusions (pivot shafts 23) is provided at the end of an arm member 23b which in turn is connected to or integrally formed with upper paper guide 62. By bending arm member 23b and disengaging the pivot shaft 23 from the shaft receiving hole 23a movable part 39 can be detached from printer main unit 38. As shown in Fig. 3, movable part 39 is installed in a rotatable manner in an upper rear position of printer main unit 38 to allow the exposure of paper route 24 formed by upper paper guide 62 and lower paper guide 64 both of which extend from paper supply ports 40 and 41 on the back side of the printer to the printing position. Recording paper 7 to be supplied to paper port 40 is journal paper which is kept by stores for sales management and inventory purposes. As shown in Figs. 1 and 2, journal paper 7 that has been printed continually passes through the upper area of movable part 39 and is taken up by take-up reel 16 installed on the back side of printer main unit 38. Take-up reel 16 is rotated by drive belt 17 which is driven by the paper-feeding mechanism inside printer main unit 38. The recording paper to be supplied to paper supply port 41 is receipt paper 8 to be handed to customers, and after printing, is sent to receipt discharge port 18 provided on the top of movable part 39. As shown in Fig. 4, stamp set 20 for imprinting a store name, etc. is detachably mounted below paper supply port 41 into which receipt paper 8 is supplied. Note that since Fig. 3 is a cross-section along C - C in Fig. 1, it does not show stamp set 20. However, in order to show the insertion direction of stamp set 20 and its position inside the printer main unit, the position of stamp set 20 viewed from the direction of arrow B in Fig. 1 is indicated by two-dot-chain lines in Fig. 3. As shown in Figs. 1 and 3, paper supply ports 40 and 41 are provided side by side on the back side of movable part 39. Feed-out rollers 22 for feeding out journal paper 7 and receipt paper 8 are provided in paper supply ports 40 and 41, respectively, and fixed to a roller shaft 22a. As shown in Fig. 3, roller shaft 22a is provided in a position that its axis is elevated by a specified height above the pivot axis of movable part 39, i.e., a position that is toward the upper edge of the back side of movable part 39. Feed-out rollers 22 are always turning when the printer is active, and when the paper is made taut by the drive force generated by paper feed roller 66 during the feeding of journal paper 7 and receipt paper 8, a frictional force is generated between feed-out rollers 22 and the paper, thus feeding the paper out. This reduces the paper feeding load caused by the inertial mass of the paper roll, etc. In more detailed terms, drive gear 59 is provided on said roller shaft 22a on the side of movable part 39, and the roller shaft is mounted in a rotatable manner on part 63 of upper paper guide 62, which forms paper supply ports 40 and 41. Transmission gear 60, which rotates roller shaft 22a by engaging with drive gear 59, is supported coaxially with the pivot axis of movable part 39, on the side of printer main unit 38. Because of this configuration, drive gear 59 on the side of movable part 39 does not disengage from transmission gear 60 on the side of printer main unit 38 when movable part 39 is opened. The rotational axis of transmission gear 60 may be arranged to coincide with the pivot axis of movable part 39 as in this embodiment. It is also possible to position the axis of transmission gear 60 and pivot axis of the movable part slightly apart from each other so that the distance between the axis of drive gear 59 and the axis of transmission gear 60 increases within a range that does not cause the two gears to disengage from each other when movable part 39 is opened. Note that stamp set 20 is positioned immediately below paper route 24 which guides recording paper 8 fed out by one of the feed-out rollers 22. As shown in Figs. 5 and 6, auto cutter mechanism 36 for cutting continuous receipt paper 8 and auto cutter drive source 37 for driving auto cutter mechanism 36 are provided inside movable part 39. As shown in Figs. 4 and 6, auto cutter mechanism 36 moves movable blade 26, which cuts receipt paper 8 in cooperation with fixed blade 28, back and forth in the direction (direction of arrow A in Fig. 5) perpendicular to the plane of receipt paper 8, by means of crank-shaped rocking lever 27. Auto cutter drive source 37 which drives auto cutter mechanism 36 is a high-torque type motor, and as shown in Fig. 4, is positioned below writing platform 44a used for correcting journal print and provided in cutter frame 43 of movable part 39, and is covered by motor cover 44b for the sake of safety. When the printer is placed horizontally, it is desirable to move the journal paper perpendicularly to the viewpoint of the operator, such as a store clerk, who must check the print result of the journal paper, etc. To achieve this, writing platform 44a is formed by bending a thin metal plate so as to define a predetermined angle with, for example, a desk surface and thus a space is defined under the writing platform. In this embodiment, the space below writing platform 44a is used for housing a DC motor which may be used as cutter drive source 37. It is also possible to form the writing platform as a part of cutter frame 43. The output shaft of cutter drive source 37 drives, via gear train 45, gear 47 which is formed in one piece with cam plate 46. Drive pin 48 is embedded in gear 47 and engaged with guide hole 49 formed on rocking lever 27 so as to rock rocking lever 27 around rocking center axis 50 as gear 47 rotates. Protruding pin 51 provided on the tip of rocking lever 27 goes through guide hole 52 provided in cutter frame 43 and is fitted into engagement groove 53 of movable blade 26 which is overlaid on cutter frame 43 in a slidable manner. The rocking motions of rocking lever 27 move movable blade 26 back and forth via pin 51. Plate-shaped upper cover 54 which covers movable blade 26 is provided on cutter frame 43. Therefore, movable blade 26 slides inside the gap between cutter frame 43 and upper cover 54 according to the movement of rocking lever 27. Support frame 56, which supports rocking center axis 50 of rocking lever 27 while allowing free rotation, forms the operation space for gear train 45 and rocking lever 27 when top edges 56a and 56b of the side walls provided on both sides are fastened to cutter frame 43. The rotation of cam plate 46, integrated with gear 47, is detected by position sensor 57 having a pair of arms provided with light emitting and receiving elements, respectively, defining a light beam path therebetween, the arms being placed so that the light beam can be interrupted by cam plate 46. The rotation of cutter drive source 37 is controlled in accordance with the output of position sensor 57 as described below. Cam plate 46 comprises two parts having different diameters. Reference numeral 46a in Fig. 6 denotes a part having a larger diameter, 46b a part having a smaller diameter. A reference position of cam plate 46 is defined as the rotational position where a transition from part 46b to 46a is detected by position sensor 57 while cam plate 46 rotates in a predetermined direction. A partial cut position of cam plate 46, where receipt paper is partially cut allowing an operator to completely cut it manually afterwards, is defined as the rotational position where a transition to part 46b from 46a is detected while cam plate 46 is further rotated in the same direction. When power is supplied to the device or the device is initialized, cutter drive source 37 is driven to make cam plate 46 rotate to the reference position. Thus movable blade 26 is set at a standby position. When the partial cut is required, firstly cam plate 46 is rotated to the partial cut position from the reference position by cutter drive source 37, then cutter drive source 37 is reversed to return cam plate 46 to the reference position. In a full cut operation, cam plate 46 is fully rotated by cutter drive source 37 from the reference position to the reference position in accordance with position sensor 57. Next, upper paper guide 62 will be described in detail. As shown in Fig. 3, part 63 of upper paper guide 62, which is positioned near paper supply ports 40 and 41, acts as a lower paper guide for guiding the bottom side of the recording paper. This configuration prevents paper supply port formation area 68 of upper paper guide 62 from interfering with the lower paper guide when movable part 39 rotates around pivot axis 23. That is, since the part 63 forming an extension of the lower paper guide, which is located within the rotational path of paper supply port formation area 68 is fixed to the upper paper guide in the present embodiment, this part is separated from the lower paper guide and is allowed to rotate with the upper paper guide. In this way, movable part 39 can be rotated to any desired angle. In above-described printer 35, auto cutter mechanism 36 which requires a large drive torque is driven by dedicated cutter drive source 37 installed in movable part 39. This allows the drive motor installed in printer main unit 38 to be a small, low-torque motor which only needs to drive the printing mechanism and the paper-feeding mechanism, both of which require a relatively small drive torque. Consequently, the specification of the drive motor to be installed in printer main unit 38 can be optimized, achieving reductions of both production cost and device size. Furthermore, even if a paper jam occurs inside auto cutter mechanism 36 of movable part 39, it is possible to open movable part 39 and to move the movable blade of the cutter to remove the clearly visible jammed paper, because dedicated cutter drive source 37 is installed inside movable part 39. This results in easy problem correction and superior maintainability. Additionally, the space below writing platform 44a for correcting journal print was conventionally not used at all. Therefore, by locating cutter drive source 37 below writing platform 44a, the space below said writing platform 44a can be efficiently used and it is possible to prevent the installation of cutter drive source 37 from increasing the size of movable part 39. In the above described embodiment of the present invention, auto cutter mechanism 36 is provided with both movable blade 26 and fixed blade 28 on cutter frame 43. However, the present invention is not limited to such a configuration but applicable to an auto cutter mechanism having a fixed blade separated from the cutter frame and fixed to the body frame which does not move when the movable part moves to open the transport path. By utilizing this configuration, it becomes easier to set a paper roll with the movable part opened because the paper need not be put through an opening of the cutter frame defining a fixed blade. Further, feed-out rollers 22 and their roller shaft 22a may be positioned below pivot axis 23 of the movable part, in order to prevent feed-out rollers 22 and roller shaft 22a from interfering with the movable part when it is opened. Furthermore, stamp set 20 may be positioned immediately below paper route 24 through which paper fed out by feed-out roller 22 passes. However, in such a configuration, paper supply ports 40 and 41 to be positioned in the back part of the printer, and the stamp set insertion position are located well below the movable part. This makes visual observation difficult when inserting paper into paper supply ports 40 and 41 or when supplying ink to stamp set 20, resulting in poor operability. In the present embodiment, paper supply ports 40 and 41 in the back of the printer are provided on the back side of movable part 39 and feed-out rollers 22, which feed out recording papers 7 and 8 inserted into paper supply ports 40 and 41 toward print head 5, are positioned above pivot axis 23 of movable part 39. As a result, paper supply ports 40 and 41 and the mounting position of stamp set 20 can be located in a relatively high position in the back part of the printer. Therefore, paper can be inserted into paper supply ports 40 and 41 or ink can be supplied to stamp set 20 while visually observing these processes from the front of the printer, resulting in improved operability. Furthermore, moving up the position of feed-out rollers 22 has increased the contact angle of feed-out rollers 22 with the paper, and as a result, the rotational torque transmitted to the feed-out rollers can be transmitted to recording papers 7 and 8 with decreased loss. As described in detail above, in the printer of the present invention, even if a paper jam occurs inside the auto cutter mechanism of the movable part, it is possible to open the movable part and to move the movable blade of the cutter to remove the clearly visible jammed paper because the dedicated cutter drive source is installed inside the movable part. This results in easy problem correction and superior maintainability. Additionally, the space below the writing platform for correcting journal print was conventionally not used at all. Therefore, by locating the cutter drive source below the writing platform, the space below said writing platform can be efficiently used and it is possible to prevent the installation of the cutter drive source from increasing the size of the movable part.

Claims: A printing apparatus comprising: a body frame (38), printing means (5) for printing on a first recording medium, a transport path (24) for guiding said recording medium to said printing means, a platen (65) disposed facing said printing means, a cover (39), disposed on said body frame on the side of said transport path opposite to said printing means an auto cutter (36) mounted on said cover (39), said auto cutter comprising a cutter frame (43) for fixing the auto cutter to said cover (39), and a cutter blade (26) movably supported on the cutter frame for cutting said recording medium printed by said printing means, and a cutter drive source (37) for driving said cutter blade to cut said recording medium, said cutter drive source (37) being fixed on said cutter frame, with said cover (39) being provided with a pair of pivots (23, 23a) at end portions thereof opposite said printing means and is pivotally supported by said body frame (38) via said pair of pivots, said cover being provided with a first recording medium guide (62) for guiding a first surface of the recording medium, said body frame being provided with a second recording medium guide (64) for guiding a second surface of said recording medium opposite to said first surface, and said first and second recording medium guides together forming said transport path (24). A printing apparatus according to Claim 1 wherein said platen (65) is mounted to and movable with said cover (39). A printing apparatus according to Claim 1 or 2 comprising a printing mechanism for printing a second recording medium positioned side by side with said first recording medium, wherein said cover (39) is further provided with a support means (44a) for supporting, in a flat orientation at a specified angle, the surface of said second recording medium opposing the surface to which printing has been applied, and wherein said cutter drive source (37) is positioned in a space defined by said support means. A printing apparatus according to Claim 1, 2 or 3 further comprising a feed-out roller (22), disposed for frictionally engaging said recording medium when tension force is applied to said recording medium, for feeding the recording medium into said transport path (24), wherein said pair of pivots of said cover is supported at a position of the body frame lower than said feed-out roller (22). A printer according to Claim 4 wherein said cover (39) further comprises a third recording medium guide (63) forming an inlet of said transport path (24) and being arranged to guide, in cooperation with said second recording medium guide, said second surface of said recording medium. A printing apparatus according to any one of Claims 4 and 5 wherein said feed-out roller (22) is driven through a transmission gear (60) rotatably mounted on said body frame on an axis positioned roughly on the same axial line as said pair of pivots of the cover (39).

Inventors: GOTO AKIHIRO, IWAYA SATOSHI, MURAKOSHI KEIJI, NEBASHI MITSUHIKO, GOTO, AKIHIRO, IWAYA, SATOSHI, MURAKOSHI, KEIJI, NEBASHI, MITSUHIKO, Goto, Akihiro, c/o Seiko Epson Corp., Iwaya, Satoshi, c/o Seiko Epson Corp., Murakoshi, Keiji, c/o Seiko Epson Corp., Nebashi, Mitsuhiko, c/o Seiko Epson Corp.
Applicants: SEIKO EPSON CORP, SEIKO EPSON CORPORATION
Application year: 1996
Main classification: B41J11
IPC codes: B41J11, B26D1, G07G5