GB2248226A - Stocking printing sheets - Google Patents

Abstract

A printer with a platen 2, and a print head 6 mounted on a carriage 5 comprises a stock 19 from which sheets PS to be printed are fed to an inlet 2b and formed on the stock 19 is a stocking means 26, 26a, 26b for receiving and holding discharged sheets after being printed thereon. A sheet feed motor 9 acts via gears 9, 10, 12, 16, 17, 18 to control rotation of platen 2, feed roller 23 and cams 27. A control circuit is described (Figure 6). <IMAGE>

Description

PRINTER HAVING COMPACT SHEET STOCKING MECHANISM The invention relates to a printer having a compact sheet stocking mechanism and, more particularly, to a printer having a compact sheet stocking mechanism including a sheet feeder capable of feeding cut sheets one by one and sheet storing portion for storing sheets after being printed and discharged.

In a printer previously proposed by the applicant, as shown in Figs. 9 through 12, an automatic sheet feeder 19A is detachably mounted on an upper cover 11 of the printer.

As shown in Fig. 11, a platen 2 is rotatably supported on a platen shaft 2a projecting fro both ends thereof between a pair of printer frames la (Fig. 9) and a sheet PS is wound around the circurference of the platen 2. A guide shaft 3 and a guide rail 4 extend parallel to the platen 2 between the printer frames la. A carriage 5 is disposed on the guide shaft 3 and guide rail 4 for laterally reciprocal movement and a printhead 6 is mounted on the carriage 5. A printing operation is performed, with respect to the sheet PS, by the printhead 6 while the carriage 5 is reciprocally moved along the platen 2.

As illustrated in Fig. 9, a sheet feed motor 7, ccnsisting of a pulse motor, is mounted at the left end of the platen 2 (as viewed from the front of the printer) outside the printer frame la by means of a fixing plate 8 bent in an L shape and attached to the printer frame 12 (hereinafter referred to as a side plate). A gear 9 is fixed on the shaft of the motor 7 and meshes with another gear 10 attached to the left end of the platen shaft 2a via deceleration gears 12 rotatably mounted on a shaft 13.

Each time a line is printed on the sheet PS, by the printhead 6, the sheet feed motor 7 is rotated so that the platen 2 is rotated counterclockwise (arrow Q) in Figs.

10, 11 and 12 by a predetermined amount via the gears 9, 12 and 10, whereby the sheet PS is fed.

A roller shaft 22 is rotatably supported by both side frames la. A pair of feed rollers 23 are attached to the roller shaft 22 in such a manner as to be rotated together with the shaft 22 and to be in contact with the upper surface of the uppermost sheet PS in a stock 19.

The stock 19 for stocking a quantity of the sheets PS is mounted on the printer cover 11 and the sheets PS are fed one by one from the stock 19 to the platen 2.

A pair of sheet support plates 40 of the automatic sheet feeder 19A are laterally (perpendicular to the feeding direction of the sheet PS) removably inserted in the slots 25 in the cover 11 of the printer, and a sheet tray 26a is formed by the upper surfaces of the sheet support plates 26 while sheet width restricting surfaces 26b are forred at both ends thereof. The sheet support plates 26 can be laterally moved as can the feed rollers 23 to correspond to the width of the sheet PS.

Press merber 29 is turnably supported on the sheet support plates 26 in such a manner that the engagement prcjection 29a thereof is engaged with engagement grooves 26c formed above the sheet supporting plates 26 so as to be positioned on a side opposite to the feed rollers 23 with. respect to the sheets PS in the stock 19.

An operation shaft 30 is turnably interposed between the side plates la and 1b of the frame 1. When the operation shaft 30 is rotated clockwise (Arrow P), cans 27 rotated integrally with the operation shaft 30 are operated so that the press members 29 are moved toward the feed rollers 23 to press the printing sheets PS against the feed rollers 23. In this state, the feed rollers 23 are rotated counterclockwise (arrow Q) in Fig. 11, and consequently, the uppermost printing sheet PS can be fed toward the inlet 2b through a first sheet passage 14.

As depicted in Fig. 9, the gears 9, 12, 10, 16 and 17, acting as a first transmission mechanism, are disposed between the sheet feed motor 7 and the feed rollers 23, and the rotation of the sheet feed motor 7 can be transmitted to the feed rollers 23 via the first transmission mechanism. Moreover, the gears 9, 12 and 18 and a spring clutch 28 are interposed as a second transmission mechanism between the sheet feed motor 7 and the cams 27, so that the rotation of the sheet feed motor 7 can be transmitted to the cams 25.

When the gears are rotated in the directions indicated by arrows P in Fig. 12, the operation shaft 30 operates in cooperation with the gear 18, to which it is engaged, and the gear 18 and the shaft 30 are smoothly released when the rotational force exceeds a predetermined value, that is, the fastening force between the shaft 30 and the gear 18. meanwhile, when the gears are rotated in the directions indicated by arrows Q in Fig. 12, the inner diameter of the spring 28 is enlarged so that the gear 1 & and the shaft 30 are released from each other.The printing sheets PS are pressed against the feed rollers 23, by the pressing movement of the press member 29, so that when a contact pressure of the sheets PS and feed rollers 23 exceeds a predetermined value, the spring clutch 28 is released to cut the operational connection between the gear 18 and the operation shaft 30 and cars 27, thereby reducing the pressing operation of the press members 29.

A plurality of drawing rollers 21 are rotatably supported via roller shafts 37 and gear 15 in a housing 40 of the sheet feeder above a printed sheet discharge port 2c formed in the upper cover 11. When the drawing rollers 21 are rotated counterclockwise (arrow Q), as shown in Figs. 10 and 11, a printed sheet PS, after being printed on the platen 2, is fed outward from a drawing port 38 formed in the housing 40. There is provided a sheet tray 39 made of a bent metallic wire on the housing 40 in the proximity of the drawing port 38. The printed sheet PS fed out from the drawing port 38 can be received and stored on the sheet tray 39 (as depicted by a dashed line in Fig. 11) However, the printer as described above is large in size and has many component parts, such as roller shafts 37 and sheet tray 39 resulting in assembly problems and a high cost.

It is therefore an object of the present invention to overcome the above described disadvantages and to provide a printer having compact sheet stocking mechanism.

Another object of the invention is to provide a printer including an automatic sheet feeding mechanism and a sheet storing mechanism of a small size having a low cost.

To attain the cited and other objects, according to the invention, there is provided a printer comprising: stocking means for stocking printing sheets to be printed on; storing means formed on said stocking means for storing printed sheets being separately fro the printing sheets; printing means for printing data on printing sheets; sheet feeding means for drawing the printing sheets stocked in said stocking means one by one and for feeding the printing sheets to said printing means; and sheet discharging means for discharging the printed sheets to said storing means after the printing sheets have been printed by said printing means.

According to a further aspect of the present invention, there is provided a print sheet stocking mechanism for use with a printer, comprising: a stocking tray having a mounting means for engaging with the printer; a drive source; a first transmission mechanism meshed at a first end to said drive source; a feed roller means meshed with a second end of said first transmission mechanism for feeding a top most print sheet from said stocking tray; and a discharge receiving means for receiving the print sheet after printing by the printer, a portion of said discharge receiving means being part of said stocking tray.

In a printer having the structure described above, a stack of sheets are stocked in the stocking means. The sheets stocked in the stocking means are fed by the sheet feeding means and the sheets are printed by the printing means. The printed sheets are discharged to the storing means by the sheet discharging means. The .storing means for storing printed sheets, after being printed, is formed on the stocking means for sheets before being printed, so that the storing means is formed at a low cost and has a simple structure.

Therefore, the printer, according to the invention, can be constructed at a low cost and has a simple structure without the complicated mechanisms for the sheet discharge mechanism and the stock for discharged sheets found in the conventional printer.

The invention will be more clearly understood by way of example only with reference to the accompanying drawings, in which: Fig. l(a) is a cross sectional view showing the structure of a stocking mechanism for printer in a preferred embodiment according to the present invention; Fig. l(b) is a partial perspective view showing a portion of the printer stocking mechanism in the embodiment; Fig. 2 is a top view of principal parts of a printer in a preferred embodiment of the invention; Fig. 3 is a sectional view taken along a line A-A of Fig. 2; Fig. 4 is a sectional view taken along a line E-B of fisc. 2; Fig. 5(a) is a perspective view of the operation of the spring clutch; Fig. ;;(L) is an overhead view of the spring clutch; Fig. 6 is a block diagram showing a control circuit for ccntrolling z sheet feed motor; Fig. 7 is a flowchart showing the flow of the sheet feed operation; Fig. 6 is a partial cross-sectional view of the stocking mechanism showing a state where a cam in Fig. 4 is roved; Fig. 9 is 2 tcr view of a conventional printer; Fic. 1C is a sectional view taken along a line A-A of Fig. S; Fig. 11 is a partial cross-sectional view of essential parts of the stocking mechanism of a conventional printer; and Fig. 12 is a sectional view taken along a line B-B of Fig. 9.

In a printer employing the sheet stocking mechanism of the embodiment shown in Fig. l(a), a platen 2 is rotatably supported on a platen shaft 2a projecting from both ends thereof between printer side plates la (Fig. 2) and a sheet PS is wound around the circumference of the platen 2. An inlet 2b for introducing the sheet PS is formed above the printer frame 1 provided behind the platen 2. In addition, a guide shaft 3 and a guide rail 4 extend, parallel to and in front of the platen 2, between the printer frames la. A carriage 5 is disposed on the guide shaft 3 and guide rail 4 for laterally reciprocal movement and a printhead 6, which functions as the printing means, is mounted on the carriage 5.A printing operation is performed, with respect to the sheet PS mounted on the platen 2, by the printhead 6 while the carriage 5 is reciprocally moved along the platen 2.

As illustrated in Fig. 2, a sheet feed motor 7, comprising a pulse motor, is arranged at the left end of the platen 2 outside the left printer side plate la by means of a fixing plate 8 bent in an L shape and attached to the printer side plate la. A gear 9 is fixed on the shaft of the motor 7 to mesh with gear 10, fixed at the left end of the platen shaft 2a, via deceleration gears 12 rotatably mounted on a shaft 13. Each time one line is printed on the sheet PS by the printhead 6, the sheet feed motor 7 is rotated so that the platen 2 is rotated counterclockwise (Arrow Q) (Figs. 1, 3 and 4) by a predetermined amount via the gears 9, 10 and 12 whereby the sheet PS is fed. On a frame cover 11, shown in Figs. l(a) and l(b), is mounted a stock 19 for stocking a stack of sheets PS.Although described in detail later, the sheets PS are fed one by one from the stock 19 to the inlet 2b.

As illustrated in Figs. l(b) and 8, a sheet insertion port 20 is formed in the upper cover 11, and a sheet PS can be manually inserted through the sheet insertion port 20 to the inlet 2b (Fig. 8) when feed rollers 23 are separated from the uppermost sheet PS in the stock 19.

Next, the structure of the stock 19 and a device for feeding the sheets PS from the stock 19 will be explained in detail. As shown in Fig. 2, a roller shaft 22 is rotatably supported between the printer side plates la of the frame 1. A pair of feed rollers 23 are mounted on the roller shaft 22 via sleeves (not shown), in such a manner as to be rotated together with the shaft 22 and be relatively movable in a lateral direction (perpendicular to feeding direction of the sheet PS), so as to face and be in contact with the upper surface of the uppermost sheet PS in the stock 19.

A pair of slots 25, extending laterally, or parallel to platen 2, are cut in the upper cover 11 behind the roller shaft 22. A pair of sheet support plates 26, which are a part of the stock 19, are laterally movably inserted in the slots 25. A sheet tray 26a is formed by the upper surfaces of the sheet support plates 26 while sheet width restricting surfaces 26b, which function as sheet width restricting means, are formed on both sides thereof. Therefore, the sheet support plates 26, the sheet tray 26a and the sheet width restricting surfaces 26b function as a stocking means. The upper portions 26d of sheet width restricting surfaces 26b are bent inward, as shown in Fig. l(b), to create a sheet tray for receiving and holding discharged sheets PS after being printed thereon. Therefore, the upper portions 26d, which function as an upper guide means, and a sheet stand 41 described below function as a storing means.

The sheet stand 41 and the upper cover 11 are made of resin as an integral unit. The sheet support plates 26 can be laterally moved as can the feed rollers 23 to correspond to the width of the sheet PS being used.

Press member 29, which functions as a pressure means, is turnably supported on the sheet support plates 26 in such a manner that the engagement projections 29a of the press member 29 is engaged with engagement grooves 26c formed in an upper rear position of the sheet supporting plates 26 so that the press member 29 -is positioned opposite to the feed rollers 23 and behind the sheets PS in the stock 19. An operation shaft 30 is rotatably mounted between the side plates la of the frame 1. When the operation shaft 30 is rotated clockwise (Arrow P), cams 27, mounted on operation shaft 30, rotate integrally with the operation shaft 30 so that the press members 29 are moved toward the feed rollers 23 to press the sheets PS against the feed rollers 23. Thus, when the feed rollers 23 are rotated counterclockwise, as shown in Fig.

l(a), the uppermost sheet PS is fed toward the inlet 2b through a first sheet passage 14.

As depicted in Fig. 2, the gears 9, 12, 10, 16 and 17, acting as a first transmission mechanism, are located between the sheet feed motor 7 and the feed rollers 23, and the rotation of the sheet feed motor 7 can be transmitted to the feed rollers 23 via the first transmission mechanism. Moreover, the gears 9, 12 and 18 and a spring clutch 28, acting as a second transmission mechanism, are located between the sheet feed motor 7 and the cams 27 so that the rotation of the sheet feed motor 7 can be transmitted to the cams 27. The spring clutch 28 is structured as shown in Figs. 5(a) and 5(b).When the gears are rotated in the directions indicated by arrows P in Fig. 4, the operation shaft 30, being attached to the gear 18 by the coiled spring clutch 28 through which it passes so as to cooperate with the gear 18, presses cams 27 against press member 29 to ensure a firm contact between rollers 23 and uppermost sheet PS. The gear 18 and the shaft 30 are smoothly released when the rotational force exceeds a predetermined value, that is, a fastening force between the spring clutch 28 and the shaft 30.

Meanwhile, when the gears 18 are rotated in the directions indicated by arrows Q in Fig. 4, the inner diameter of the spring clutch 28 is enlarged so that the gear 18 and the shaft 30 are released from each other. Thus, during feeding operation of the printer, the sheets PS are pressed against the feed rollers 23 with the pressing movement of the press member 29 so that when the contact pressure of the sheets PS and feed rollers 23 exceeds a predetermined value, the spring clutch 28 is released to cut the operational connection between the gear 18 and the operation shaft 30 mounting cams 27, thereby reducing the pressing operation of the press member 29 below the predeterined value.

A space between the sheet stand 41a and the upper cover 11 above the platen 2 serves as a sheet discharge port. A resilient member (plate spring) 42 having sheet discharge rollers 43, which function as a discharging means or a discharge receiving means, attached to the tip end thereof is fixed to the upper cover 11 in front of the port. The sheet discharge rollers 43 are urged toward the platen by the resilient member 42. The sheet stand 41a, which functions as a sheet supporting means, has an arcuate upper shape and is integrally formed in the upper cover 11 between the sheet insertion port 20 and the sheet discharge port. A claw 41c of the sheet stand 41a formed at the forward end thereof projects upward slantwise with the distal end thereof is formed in a hook shape.The shape of the claw is set in such a manner that the printed sheets PS, discharged by the discharge rollers 43, fall into the recess formed at the bottom of the claw. The sheet stand 41a and the upper cover 11 are made as a unit of resin.

For the printer described above, the control circuit for controlling the sheet feed motor 7 will now be explained with reference to Fig. 6. A central processing unit (CPU) 61, the control means, is connected to a read only memory (ROM) 62 and a random access memory (RAM) 63.

The ROM 62 stores the program for controlling the operation of the printer to include the number of supply pulses for obtaining a predetermined rotational angle in a direction opposite to that of the sheet feed motor 7 in the automatic sheet feed mode (wherein a pulse motor is used as the sheet feed motor 7) and the number of supply pulses for obtaining a predetermined rotational angle in a direction of the sheet feed motor 7 in the automatic sheet feed mode.

The CPU 61 is also connected to a first sheet feed switch 64, for starting the automatic sheet feed operation that is positioned on the cover of the printer, via an input interface 65 so as to receive a start signal from the sheet feed switch 64. The CPU 61 is further connected to the sheet feed motor 7 through an output interface 66 and a driver 67 so as to output a drive or stop signal to the sheet feed motor 7.

The automatic sheet feed operation of the printer will now be explained. In a sheet feed operation for feeding the sheets PS onto the platen 2 of the printer, a program, as shown in a flowchart of Fig. 7, is executed under the control of the CPU 61. First, the CPU 61 determines in step S1 whether the sheet feed switch 64 is turned on. Upon the turning-on of the sheet feed switch 64, the program proceeds to step S2. In step S2, the sheet feed motor 7 is rotated in a direction opposite to that of the printing operation and, in step S3, a decision is made whether the predetermined number of rotation steps stored in the ROM 62 have been completed. The steps S2 and S3 are repeated until the predetermined number of rotation steps are completed.

When the platen 2 is rotated in the direction indicated by the arrow P, in Fig. 1, by the rotation of the sheet feed motor 7 by the predetermined amount, the roller shaft 22 is rotated in the direction indicated by the arrow P, Fig. 4, via the first transmission mechanism in a connection relationship so that the feed rollers 23, disposed on the roller shaft 22, are rotated counterclockwise (Arrow P) in Fig. 1(a) . Moreover, the cams 27 are rotated in the direction P by the second transmission mechanism. The press members 29 are moved under pressure toward the feed rollers 23 by the cams 27 so that the sheets PS are pressed against the feed rollers 23.

Accordingly, the uppermost sheet PS in the stock 19 is fed toward sheet feed rollers 33, which are pressed against the platen 2 by a plate spring 31 fastened to the frame 1 by means of a clamp screw 32, through the first sheet passage 14 and the inlet 2b. At this time, the sheet feed rollers 33 are rotated in a direction reverse to a sheet feed direction, indicated by the arrow P in Fig. 4, through the first transmission mechanism. Consequently, the sheet PS cannot pass between the sheet feed rollers 33 and the platen 2 so that the lead edge of the sheet PS stops at a contact point 34 between the rollers 33 and the platen 2.

During the feed operation of the sheet PS, when the contact pressure of the sheet PS and the feed rollers 23 exceeds a predetermined value1 as a result of the pressing movement of the press members 29, the spring clutch 28, shown in Figs. 2 and 5, is released. As a result, the operational connection between the gear 18 and the operation shaft 30 and cams 27 is broken to reduce the pressing operation of the press members 29 to the preXeter..ined value. Accordingly, the sheets PS are pressed against the feed rollers 23 under constant contact pressure independent of the number of stacked sheets PS in the stock 19 and the uppermost sheet PS is securely fed from. the stock 19 by the rotation of the feed rollers 23.

When the sheet feed motor 7 is rotated by a predetermined number of steps in the direction (Arrow P) opposite to the sheet feed direction (Arrow Q) in the printing operation so that the sheet PS in the first sheet passage 14 is slightly curved as indicated by a broken line in Fig. l(a), the program proceeds from step S3 to step SA as shown in Fig. 7, under control of the CPU 61.

In step S4, the sheet feed motor 7 is rotated in the sheet feed direction for the printing operation. Then, in step S5, a decision is made whether the predetermined number of rotation steps, stored in the ROM 62, have been completed.

The steps S4 and S5 are repeated until the predetermined number of rotation steps are completed.

When the platen 2 is rotated in the direction indicated by the arrow Q in Fig. l(a) according to the rotation of the sheet feed motor 7 in the sheet feed direction, the sheet feed rollers 33 are rotated clockwise (Arrow Q, Fig. 1(a)) via the first transmission mechanism so that the sheet PS passes between the sheet feed rollers 33 and the platen 2 to be fed onto the platen 2. At this time, the feed rollers 23 are rotated clockwise (Arrow P, Fig. 1(a)) through the first transmission mechanism.

Further, with the rotation of the gear 18 in the direction of the Arrow Q, the cams 27 are also rotated in the direction of the Arrow Q by the friction between the spring clutch 28 and the operation shaft 30. The cams 27 abut therefore cam stoppers 36, which define a stop means, mounted in the frame 1, with the further rotation of the gear 18 in the direction of the arrow Q. The spring clutch 28 is expanded to release the shaft 30 at this time. As a result, the press members 29 are moved away from the feed rollers 23 to remove the pressing operation of the sheets PS, with respect to the feed rollers 23, and the top most sheet PS cannot be fed (Fig. 8).

F;hen the printing sheet PS is interposed between the platen 2 and the printhead 6, as depicted by a broken line in Fig. 8, by the rotation of the sheet feed motor 7 by the predetermined steps in the sheet feed direction (Arrow Q), the rotation of the sheet feed motor 7 is stopped thereby completing the sheet feed operation.

Since the lead edge of the sheet PS had been previously positioned at the contact point 34 between the sheet feed rollers 33 and the platen 2 (Fig. l(a)), a constant print start position is established by the rotation of the motor 7 by the predetermined number of steps. After that, the printing operation is performed with respect to the sheet PS, mounted on the platen 2, by the printhead 6 while the carriage 5 is reciprocally moved along the platen 2. Upon completion of a line of printing, the sheet feed motor 7 is rotated in the sheet feed direction (Arrow Q) so that the sheet is fed by a predetermined amount according to the rotation of the platen 2.At the same time, the leading edge of the sheet PS is guided by sheet guide surfaces lia, provided in sheet guide ribs llb formed in the upper cover 11, and the printed sheet PS is discharged from the platen 2 by the discharge rollers 43 which are urged in a direction R, against the platen 2, by the resilient member 42 (Fig. 8).

The printed sheet PS is completely discharged from the print area by the rotation of the discharge rollers 43 and platen 2.

The lead edge of the printed sheet PS, discharged by the discharge rollers 43 abuts against the sheet stand 41a of the upper cover 11 to be directed upwardly. The lead edge of the printed sheet PS slides upwardly along the sheet tray 26d. Upon discharge of the trail edge of the printed sheet PS, the printed sheet continues to move upwardly, for an instant, as a result of inertia to fall in the discharge stock 41 formed by the upper portions 26d, that define the sheet tray, and the sheet stand 41a.

It is to be noted that the present invention is by no means limited to the above embodiment and can be practiced in various ways without departing from the spirit of the invention.

Claims (21)

1. A printer comprising: stocking means for stocking printing sheets to be printed on; storing means formed on said stocking means for storing printed sheets separately from the printing sheets; printing means for printing data on printing sheets; sheet feeding means for drawing and feeding the printing sheets stocked in said stocking means one by one to said printing means; and sheet discharging means for discharging the printed sheets to said storing means after the printing sheets have been printed by said printing means.

2. A printer as claimed in claim 1, wherein said stocking means comprises a sheet width restricting means erected on each side of said stocking means to abut side edges of the stocked printing sheets.

3. A printer as claimed in claim 2, wherein said storing means comprises an upper guide means formed integrally with each said sheet width restricting means, said upper guide means extending from an upper side of said sheet width restricting means toward a mid-point of said stocking means to surround the stocked sheets.

4. A printer as claimed in claim 1, 2 or 3, wherein said storing means further comprises sheet supporting means formed integrally with a printer frame.

5. A printer as claimed in claim 4, wherein said sheet supporting means is for supporting a trailing edge of the printed sheets discharged by said sheet discharging means in cooperation with each said upper guide means to store the discharged printed sheets.

6. A printer as claimed in any one of claims 1 to 4 wherein said sheet supporting means is for supporting trailing edge of the printed sheets discharged by said sheet discharging means.

7. A printer as claimed in claim 4, 5 or 6 wherein said sheet supporting means comprises a sheet stand which is upwardly convex.

8. A print sheet stocking mechanism for use with a printer, comprising: a stocking tray having a mounting. means for engaging with the printer; a drive source; a first transmission mechanism meshed at a first end to said drive source; a feed roller means meshed with a second end of said first transmission mechanism for feeding a top most print sheet from said stocking tray; and a discharge receiving means for receiving the print sheet after printing by the printer, a portion of said discharge receiving means being part of said stocking tray.

9. A print sheet stocking mechanism according to claim 8 wherein said mounting means is engageable with slots formed in a cover of the printer.

10. A print sheet stocking mechanism according to claim 8 or 9 further comprising: a pressure means for releasably pressing a stock of print sheets against said feed roller means; a second transmission means meshed at a first end with said drive source and releasably connected at a second end with a rotatable cam means, said cam means releasably engaging said pressure means.

11. A print sheet stocking mechanism as claimed in claim 10, wherein said releasable connection between said second transmission means and said rotatable cam means comprises a clutch spring mounted in a gear of said second transmission means with a shaft mounting said cams seated within a coil of said clutch spring.

12. A print sheet stocking mechanism as claimed in claim 11, wherein said clutch spring allows said shaft of said rotatable cam means to rotate when pressure above a predetermined value is encountered.

13. A print sheet stocking mechanism as claimed in claim 10, 11 or 12 further comprising a stop means for stopping said rotatable cam means when said rotatable cam means is disengaged from said pressure means.

14. A print sheet stocking mechanism as claimed in any of claims 8 to 13 wherein said stocking tray is laterally adjustable to accommodate print sheets having different widths.

15. A print sheet stocking mechanism as claimed in claim 14, wherein said variable width stocking tray has an edge guide extending from each side of said stocking tray, said edge guide contacting a side edge of a stack of print sheets.

16. A print sheet stocking mechanism as claimed in any one of claims 8 to 15 wherein said feed roller means comprises: a rotatable shaft which is meshed with said second end of said first transmission mechanism; and at least two feed rollers slidably adjustable along said rotatable rod according to a width of the print sheet.

17. A print sheet stocking mechanism as claimed in any one of claims 8 to 16, wherein said discharge receiving means comprises: an edge guide extending from each side of said stocking tray, said edge guide contacting a side of a stack of print sheets and having an inwardly turned extension extending toward a mid-point of said stocking tray; and a discharge stand integrally formed in a cover of the printer.

18. A print sheet stocking mechanism as claimed in claim 17, wherein said discharge stand has a curvalinear portion and a claw portion.

19. A print sheet stocking mechanism constructed and arranged as hereinbefore described with reference to and as illustrated by Figures 1 to 8 of the accompanying drawings.

20. A printer comprising a print sheet stocking mechanism as claimed in any one of the claims 8 to 19.

21. A printer constructed and arranged substantially as hereinbefore described with reference to and as illustrated by Figures 1 to 8 of the accompanying drawings.