PIN TRACTOR

Abstract: A pin tractor for feeding blank paper for use in various printers, typewriters, etc. which are used as output devices for electronic computers, especially for personal comput­ ers. A belt (6) carrying pins is driven to turn by a toothed pulley (7) for driving provided at a frame (9) comprising one member. The toothed pulley (7) for driving is supported to the frame (9) only at one end portion thereof and the other end portion is a flange exposed outwardly. A mark (40) for positioning is provided at the exposed surface of the other end portion of the pulley.

Description: This invention relates to a pin tractor for feeding blank paper of the kind as referred to by the preamble of claim 1. Such pin tractors as known for example from US-A 3 938 721 are generally used in various printers, typewriters, etc. serving as output devices for electronic computers, especially for personal computers. The pin tractors must operate at a fixed speed for feeding blank paper by the engagement of the pins of the driving belts with the feed perforations at the two edges of the blank paper which necessitates a synchronous movement of the two belts and therefore as well a synchronous turning of their driving pulleys. Since the known pin tractors are so designed that their driving pulleys are rotatably supported by a driving shaft between two members forming a frame, it is substantially difficult to properly synchronize the movement of the two belts by the engage­ ment of their pins with the perforations at the two edges of the blank paper when the pin tractor is being fitted to the dri­ ving shaft. With the known pin tractors the belt is mounted relatively loosely to thereby reduce the turning torque of its related driving pulleys. The belt is also guided at its two edges in an open guide groove of the frame which with its guide surfaces is arranged such that the belt runs with its blank paper feeding surface almost on the same level with the surface of the frame. Since thereby a sliding resistance between the blank paper and the surface of the frame is caused when the blank paper is being fed, a blank paper feeding load is generated and accordingly the feeding efficiency is reduced, especially in the case where blank paper quality is rough. With the loose mounting of the belt the feeding accuracy is as well reduced especially when the blank paper is fed on the belt loosening side. The present invention deals with the object of providing a pin tractor of the kind as referred to by the preamble of claim 1 which will easily allow a proper positioning of the pins of the right and left belts. In order to realize this object, the pin tractor according to the present invention is characterized by the features of claim 1 whereas the further claims refer to features that bring about additional advantages of the thusly characterized inventive pin tractor. With the inventive pin tractor it is possible to effect engagement of the belts with the driving pulleys simply by watching the positioning marks so that the synchronous running of the pins of both belts can be carried out very easily. By arranging the positioning mark preferably on a flange adjacent to the teeth part of each driving pulley it is moreover possible to obtain at the same time a high feeding accuracy with less blank paper feed load. The present invention will be understood more clearly by reading the following detailed description with reference to the accom­ panying drawing showing two preferred embodiments of the inven­ tive pin tractor. Fig. 1 is a perspective view of a blank paper feeding device using a pin tractor according to a first embodiment; Fig. 2 - Fig. 4 are a front view, a plan view and a side view, partly in section of the pin tractor of Fig. 1; Fig. 5 is a plan view of the frame; Fig. 6 is a front view of the frame; Fig. 7 and Fig. 8 are front views of the toothed driving pulley and the driven plan pulley; Fig. 9 and Fig. 10 are a front view and a side view, partly in section of the locking member; Fig. 11 is a plan view of the presser member; Fig. 12 - Fig. 14 are a front view, a plan view and cross section in part of the pin tractor according to a second embodiment; Fig. 15 is a plan view of the frame; and Fig. 16 and Fig. 17 are a plan view and a front view of the presser member. In the blank paper feeding device shown in Fig. 1, numeral 1 designates a pin tractor. Two pin tractors 1 are arranged with a space corresponding to the width of blank paper S between them and are connected by a driving shaft 2, square in cross section, and a guide shaft 3, circular in cross section, which are substantially in parallel with each other. As shown in Fig. 2 - Fig. 4, each pin tractor 1 has a belt 6 having a plurality of pins 4 engageable with feed perforations S₁ made at both edges of the blank paper S and projecting from the surface of the belt base at regular intervals. The belt 6 has also teeth 5 at the back surface of the belt base. As the belt 6 is driven, the blank paper S is fed at a substantially uniform speed. The teeth 5 of the belt 6 engage with a toothed driving pulley 7 mounted on the driving shaft 2 and a driven plain pulley 8 on shaft 3 both of which are movable in an axial direction of the respective shafts but are fixed in circumferential direction whereby the belt 6 is driven to turn. A frame 9 of the pin tractor 1 is made of synthetic resin and as shown in Fig. 5 and Fig. 6, a protrusion 11 is formed at the central part of one side of a base plate 10 which is substantially rectangular. A support part 13 which pivotally supports a presser member 12 made of synthetic resin is formed to project from the protrusion 11. Blank paper S which engages with the pins 4 of the belt 6 is held between the frame 9 and the presser member 12. Fitting holes 14,15 are provided at both sides of the protrusion 11 of the base plate 10 and extend through the base plate 10. The toothed driving pulley which is fixed to runs integrally with the driving shaft 2 is rotably supported by the fitting hole 14. As shown in Fig. 7, the toothed driving pulley 7 comprises a pulley proper 16 having a teeth part 16a, a flange 17 provided at one side of the pulley proper 16 and a protrusion 18 having a circular groove 18a. A guide part 19 formed at the opposite side of the base plate 10 is positioned in the circular groove 18a of the protrusion 18 to permit rotation in relation to the base plate 10. A mark 40 is provided at the exposed surface of the flange 17 for positioning of the belt 6 (refer to Fig. 2). The driven plain pulley 8 is rotatably supported in the fitting hole 15 through a locking member 20 which fixes the pin tractor 1 to the guide shaft 3. The fitting hole 15 is of such shape that its inside diameter varies in circumferential direction and comprises a first hole 15e having opposed flat parts 15a, 15b and circularly curved parts 15c, 15d and a second circular hole 15f which continues in axial direction of the first hole 15e. As shown in Fig. 8, the driven plain pulley 8 is provided with a protrusion 22 at one end of the pulley proper 21 which is fitted into the second hole 15f and a flange 23 at the other end. A through hole 27 for the guide shaft 3 extends through the lever part 25 and the flange part 26, of the locking Member. The tubular part 24 has opposed flat surfaces 24a, 24a extending in an axial direction. Straight slits 24c, 24c are formed on the tubular part 24 at the position about 90° shifted in circumferential direction from the flat surfaces 24a, 24a. With the above arrangement, when the locking member 20 is rotated its flat surfaces 24a, 24a come off the flat parts 15a, 15b, of the first hole 15e and the circularly curved surfaces of the tubular part 24 is controlled by the flat parts 15a, 15b, whereby the tubular part 24 deforms and reduces the insides diameter of the through hole 27 for its fastening to the guide shaft 3. Thus, the pin tractor 1 is fixed immovably to the guide shaft 3. As shown in Fig. 11, the presser member 12 has a slit 28 located at a position corresponding to the moving path of the pins 4 of the belt 6 and axis parts 29, 30 for engagement with engaging holes 13a, 13b of the support part 13 of the frame 9. The axis parts 29, 30 project from arm parts 32, 33 respectively which protrude from a base plate part 31 in the same direction. The arm part 32 is longer than the arm part 33 to allow a top part 32a of the arm part 32 to engage elastically with a concave portion 13c of the support part 13 and to hold the presser member 12 at a predetermined open position. the axis parts 29, 30 project in opposite directions. With the above arrangement, when the belt 6 is engaged with the toothed driving pulley 7 it is possible to effect engagement while watching the positioning mark 40 on the flange 17 of the toothed driving pulley 7. The position of the pins 4 of the belt 6 relative to the driving shaft 2 can thus be set easily. Accordingly, positioning of the pins 4 of the two belts 6 located at both edges of the blank paper S can be carried out easily to provide for synchronous running of the pins 4 of both belts. In the above embodiment, the belt 6 carying pins is wound round between the toothed driving pulley 7 and the driven plain pulley 8 but the provision of the positioning mark 40 at the flange of the toothed driving pulley is also applicable to the case where the belt 6 is wound round between the toothed driving pulley and the guide part 19 formed on the frame 9. When the belt 6 runs by the rotation of the toothed driving pulley 7, the belt 6 is not controlled by a guide groove of the frame proper or others parts as in the case of the conventional pin tractors. Therefore, frictional resistance is small and the blank paper feeding load is reduced. Although the movement of the belt 6 in its width direction is controlled by flanges 17, 23 of both pulleys 7, 8, flanges 17, 23 which are in contact with the belt 6 turn with the belt so that no frictional resistance is generated. In assembling the pin tractor according to the present invention, the belt 6 is provided on one side of the frame 9 and then the toothed driving pulley 7 and the driven plain pulley 8 are installed and the locking member 20 is applied to the driven plain pulley 8. thus, assembling efficiency is very high. In the above embodiment, the presser member 12 is pivotally supported in relation to the frame 9, but as shown in Fig. 12-Fig 17, the presser member can be supported in such a fashion that it is slidable in a vertical direction relative to the frame. A presser member 52 of a pin tractor 51 has a slit 53 at the position corresponding to the moving path of the pins 4 of the belt 6. The presser member has on one side thereof an axis part 56 which engages with a support hole 55a of a support 55 and a knob 57 on its other side. The axis part 56 project from a base plate 58 in a direction perpendicular to the base plate and is bifurcated into a pair of arm parts 59, 60. The arm part 59 has a first concaved part 59a and a second concaved part 59b in vertical direction. The first concaved part 59a engages elastically with an engaging pin 61 at the lower end of the support 55 for keeping the presser member 52 in a clossed position and the second concaved part 59b engages elastically with the engaging pin 61 for keeping the presser member 52 in an opened position. A groove 55b is formed at the upper surface of the support 55. When the presser member 52 is in its closed position, an engaging part 62 formed on the same side as the axis part 56 engages with the groove 55b. With the above arrangement, by pinching and lifting the knob 57 of the presser member 52, the axis part 56 slides upwardly, being guided to the support hole 55a of the support 55, whereupon the engaging pin 61 engages elastically with the second concaved part 59b of the arm part 59 and the presser member 52 is held elastically in an opened position. By depressing the presser member 52, the axis part 56 slides downwardly along the support hole 55a of the support 55, whereupon the engaging pin 61 engages elastically with the first concaved part 59a and the engaging part 62 engages with the groove 55b. Thus, the presser member 52 is held in a closed position. As stated above, opening and closing movement of the presser member 52 can be accomplished by sliding the presser member 52 in a vertical direction in relation to the frame 54. Therefore, only a small space is required for opening and closing of the presser member with a resultant simplification of the connecting mechanism of the presser member 52 and the frame 54. In the above embodiment, the presser member can be slided through the frame only from above, but it is also possible to slide it through from above or from below as is desired by forming the support 55 vertically symmetrical. Also, in the above embodiment the belt 6 is wound round between the toothed driving pulley 7 and the driven plain pulley 8 but the present invention is also applicable to the case where the belt is wound round between a toothed driving pulley and a guide formed on the frame.

Claims: 1. A pin tractor for feeding blank paper (S) having feed perforations (S₁) at two edges thereof, comprising a frame (9), a toothed driving pulley (7) rotatably supported by said frame (9), and a belt (6) having a plurality of pins (4) on one surface thereof adapted to engage with said feed perforations (S₁) at a respective edge of the blank paper (S) and also having teeth (5) on the opposite surface adapted to engage with said toothed driving pulley (7), characterized in that the toothed driving pulley (7) is rotatably supported at only one axial end portion by said frame (9) and that on an exposed surface of its opposite axial end portion a positioning mark (40) is provided for properly positioning the toothed driving pulley (7) and the belt (6) in relation to the frame (9). 2. A pin tractor as defined in claim 1, wherein the toothed driving pulley (7) has a flange (17) on said opposite axial end portion and adjacent to the teeth part (16a) of the pulley proper (16), the positioning mark (40) being provided on the exposed surface of said flange (17). 3. A pin tractor as defined in claim 1 or claim 2, wherein said supporting end portion of the toothed driving pulley (7) has a protrusion (18) by means of which it is rotatably engaged with the frame (9). 4. A pin tractor as defined in claim 3, wherein the protrusion (18) has a circumferential groove (18a) adapted to engage with a guide part (19) of the frame (9). 5. A pin tractor as defined in any of the claims 1 to 4, wherein the pin tractor (1) further includes a driven plain pulley (8) which has a protrusion (21) by means of which it is rotatably engaged with the frame (9), the protrusion (21) having a flange (23) on its axial end opposite to said guide part (19). 6. A pin tractor as defined in claim 5, wherein the frame (9) is fixed to a guide shaft (3) by means of a locking member (20) which has a tubular part (24) insertable into a first fitting hole (15e) of the frame (9) and radially deformable when rotated internally of said first fitting hole (15e) to thereby engage the guide shaft (3), the driven plain pulley (8) being rotatably supported by said tubular part (24) of the locking member (20) and being inserted by its protrusion (21) into a second fitting hole (15f) of the frame (9) which is coaxial with said first fitting hole (15e). 7. A pin tractor as defined in claim 6, wherein the shape of the first fitting hole (15e) comprises two diametrically opposed flat parts (15a, 15b) and circularly curved parts (15c, 15d) connecting said flat parts. 8. A pin tractor as defined in claims 6 and 7, wherein the locking member (20) has a lever part (25) at one axial end of the tubular part (24) and a flange (26) for stopping any slip of the driven pulley (8) at the opposite axial end, a through hole (27) extending through the locking member (20) for receiving the guide shaft (3). 9. A pin tractor as defined in any of the claims 6 to 8, wherein the locking member (20) has straight slits (24c) on the tubular part (24) which in the circumferential direction of the tubular part are provided at positions about 90° shifted from two diametrically opposed flat surfaces (24). 10. A pin tractor as defined in any of the claims 1 to 9, wherein the pin tractor (1) further includes a presser member (12) which by means of an axis (29, 30) is pivotally supported on the frame (9) for providing an opened and a closed position of the presser member (12) in relation to the frame (9). 11. A pin tractor as defined in any of the claims 1 to 9, wherein the pin tractor (1) further includes a presser member (52) which by means of an axis (56) slidably engages with a supporting hole (55a) of the frame (9) for providing an opened and a closed position of the presser member (52) in relation to the frame. 12. A pin tractor as defined in claim 11, wherein the axis (56) of the presser member (52) is bifurcated into a pair of arm parts (59, 60) of which the one arm part (59) has a concave portion (59a) for an engagement with an engaging pin (61) on the frame (9) in the closed position of the presser member. 13. A pin tractor as defined in claim 12, wherein said one arm part (59) has a second concave portion (59b) for an engagement with the engaging pin (61) also in the opened position of the presser member (52). 14. A pin tractor as defined in any of the claims 11 to 13, wherein a groove (55b) is formed on the frame (9) for an engagement with an engaging part (62) of the presser member (52) in its closed positions said engaging part extending in the same direction as the axis (56) of the presser member (52).

Inventors: DAINI, HIROSHI BANDO CHEMICAL INDUSTRIES, LTD., UENO, TOSHIHIKI BANDO CHEMICAL INDUSTRIES, LTD.
Applicants: BANDO CHEMICAL INDUSTRIES, LTD.
Application year: 1987
Main classification: B41J11
IPC codes: B41J11, B65H20