US3715027A

US3715027A - Device for correcting the deflection of a large wide endless belt

Info

Publication number: US3715027A
Application number: US00096078A
Authority: US
Inventors: S Fujimoto
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1969-12-17
Filing date: 1970-12-08
Publication date: 1973-02-06
Anticipated expiration: 1990-02-06
Also published as: DE2062324A1; CA938241A; DE2062324B2; FR2073926A5; NL7017690A; DE2062324C3; DK144928B; DK144928C

Abstract

An endless belt is trained over at least a pair of rollers, including at least one driven roller, and one of the other rollers is mounted for swinging about a pivot axis perpendicular to its axis of rotation. A pair of belt deflection detecting rollers are rotatably mounted adjacent respective opposite side edges of the belt and are spaced apart a distance slightly greater than the width of the belt so as normally to be out of engagement with the adjacent belt side edge. The detecting rollers are operatably connected to the mounting means for the swingable roller and are operable, responsive to rotation of the detecting roller by engagement with a belt side edge as a result of belt deflection, to swing the swingable roller about the pivot axis thereof in a direction to correct belt deflection.

Description

United States Patent n91 Fujimoto Feb. 6, 1973 [54] DEVICE FOR CORRECTING THE FOREIGN PATENTS OR APPLICATIONS DEFLECTION OF A LARGE WIDE 773 84 957 G B ..l98 02 E LESS BELT 8 5/ l reat main [2 [75] Inventor: Sakae Fujimoto, Chofu-shi, Tokyo, Primary Examiner-:Edward A. Sroka Japan I Attorney-McGlew and Toren [73] Ass1gnee: .llizlgshikl Kaisha Rlcoh, Tokyo, ABSTRACT [22] Filed: 8 1970 An endless belt is trained over at least a pair of rollers,

App]. No.: 96,078

including at least one driven roller, and one of the other rollers is mounted for swinging about a pivot axis perpendicular to its axis of rotation. A pair of belt deflection detecting rollers are rotatably mounted adjacent respective opposite side edges of the belt and are spaced apart a distance slightly greater than the width of the belt so as normally to be out of engage ment with the adjacent belt side edge. The detecting rollers are operatably connected to the mounting means for the swingable roller and are operable, responsive to rotation of the detecting roller by engagement with a belt side edge as a result of belt deflection, to swing the swingable roller about the pivot axis thereof in a direction to correct belt deflection.

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SAKAE Fuzra Mo'l'o DEVICE FOR CORRECTING THE DEFLECTION OF A LARGE WIDE ENDLESS BELT BACKGROUND OF THE INVENTION The provision of flanges on rollers having an endless belt trained thereover may be effective to prevent deflection of a relatively narrow endless belt from its normal path of movement between rollers. However, in the case of a very wide endless belt, the force with which the belt is deviated to either side from its normal path of movement is so large that it is not possible to prevent deflection of such a very wide endless belt by providing flanges on the belt rollers. Additionally, the provision of such flanges is disadvantageous in that the side edges of the belt and the flanges rub against each other, thereby damaging the side edges of the belt. As a consequence, it is not desirable to use devices relying on flanges rubbing against the side edges of an endless belt as a means for preventing deflection of very wide endless belts from the normal path of movement between rollers.

It has been proposed to prevent deflection of a very wide endless belt by a device of the type shown in FIG. 1. As shown in FIG. 1, a very wide endless belt 101 is trained about two

belt rollers

102 and 103, with roller 102 being so supported that it can be swung about its central portion which serves as a pivot, when the belt is deflected to either side from its normal path of movement. Roller 103, which is mounted on a shaft 105a having a gear 104 secured to an end thereof, is adapted to be rotated in the direction of the arrow a through the medium of gear 104 and by a suitable drive means which has not been shown in FIG. 1. If belt 101, moving in the direction of arrow b as roller 103 rotates, is deviated in the direction of the arrow c, belt roller 102 will be swung in the direction of arrow d until it reaches a dash-and-dot line position 102A, at which point the very wide endless belt 101 will begin to shift in a direction opposite to the direction of arrow so that the deflection of the belt is corrected.

It is well known that, when a very wide endless belt is deviated in one direction, the deviation can be corrected by swinging one of the belt rollers in a direction in which the belt is to be shifted, as mentioned above. It has hitherto been customary to provide a movable member (not shown) which is disposed on one side of endless belt 101 and adapted to be forcibly moved when belt 101 deviates from its normal path of movement so as to swing belt roller 102. The movement of the movable member is transmitted to roller 102 through a linkage or the like, so that the device requires an undesirable multiplicity of parts and is complex in construction. In addition, the pressure applied to the side edges of the belt is rather high, and consequently the belt is liable to be damaged.

In place of using a complicated linkage, it has been proposed to use electric means to detect the deviation of a belt and to cause one of the belt rollers to be swung, responsive to a signal produced by the detection means, so as thereby to move the belt back to its normal path of movement. However, such an electric device is not without disadvantages. The electric detection means must act with very high precision and accuracy, and such a means is expensive to manufacture resulting in an increase in cost. Moreover, the connection of such an electric detection means with mechanical means for actually swinging the belt roller requires ingenuity and skill, and makes theconstruction complex.

SUMMARY OF THE INVENTION This invention relates to means for correcting automatically the deflection of a very wide endless belt from its normal path of movement and, more particularly, to an improved, simplified, and more efficient belt deflection correction device particularly usable with very wide endless belts such as used in a copying machine or in a sheet conveying apparatus.

The objective of the invention is to provide such a belt deflection correction device, for a very wide endless belt trained over at least a pair of rollers, which obviates the disadvantages of all belt deflection correction devices known hitherto.

In accordance with the invention, a pair of detection rollers are mounted for relatively free rotation adjacent opposite side edges of a very wide endless belt and in positions spaced slightly from the adjacent belt side edge. The detection rollers function in a manner such that, when the belt is deflected in one direction, the side edge facing in the direction of the deflection, rotates the adjacent detection roller, and rotation of the detection roller is converted into swinging movement of one of the rollers over which the endless belt is trained.

The resistance of the deflection detection rollers to rotation can be minimized by using, me means for swinging the belt roller, a threaded rod,having a small pitch as a member for moving a swingable belt roller supporting member. This is conducive to eliminating the chance of damaging the edges of the belt brought into engagement with the detection rollers to rotate the latter. The arrangement, in which the detection roller driven by one of the belt side edges upon deviation of the belt from its normal path of movement directly swings one of the belt rollers, makes the invention device simple in construction and [low in cost.

However, the invention also contemplates other driving connections between the belt detecting rollers and the swingable mounting means supporting one of the belt rollers. Thus, for example, a movable cam member may be included in the driving means orv cams projecting radially from a detecting roller can be used as the drivingmeans. In the latter case, suitable brake means are provided to limit the rotation of the detecting roller then being driven by a side edge of the belt.

An object of the invention is to provide an improved and simplified belt deflection correction device for a very wide endless belt trained over at least a pair of rollers.

Another object of the invention is to provide such a correction device including means mounting one of the belt rollers for swinging about a pivot axis perpendicular to its axis of rotation.

A further object of the invention is to provide such a correction device including a pair of belt deflection detecting rollers rotatably mounted adjacent opposite side edges of the belt but normally out of engagement with the adjacent side edges of the: belt.

Another object of the invention is to provide such a correction device including means operatively connecting the detecting rollers to the mounting means and operable, responsive to rotation of a detecting roller by engagement with a belt side edge as a result of belt deflection, to swing one roller about the pivot axis in a direction to correct the belt deflection.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view illustrating the relative positions, in operation, of a swingable belt roller and an endless belt trained thereabout and about a fixedly positioned belt roller;

FIG. 2 is a somewhat schematic plan view, partly broken away, of a belt deflection correction deviceembodying the invention;

. FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a sectional view, on an enlarged scale, taken along the line IV-IV of FIG. 2;

FIG. 5 is a perspective view, partly broken away, of the device shown in FIG. 2 with the base plate being omitted;

FIG. 6 is a plan view of another embodiment of the correction device in which a linkage is used in place of the transmission belt shown in FIG. 2;

FIG. 7 is a front elevation view, partly in section, of the device shown in FIG. 6;

FIG. 8 is a plan view of another embodiment of the correction device in which the rotation transmission mechanism uses a linkage;

FIG. 9 is a perspective view of a portion of the mechanism of FIG. 8',

FIG. 10 is a partial perspective view of another embodiment of the correction device, showing the essential portions thereof;

FIG. 11 is a plan view corresponding to FIG. 10;

FIG. 12 is a sectional view taken along the line XII- XII ofFlG. 11;

FIG. 13 is a perspective view of still another embodiment of the correction device, showing the essential portions thereof;

FIG. 14 is a front elevation view of the correction device shown in FIG. 13;

FIGS. 15, 16, 17 and 18 are perspective views of other embodiments of a correction device in accordance with the invention, showing the essential portions thereof;

FIG. 19 is a sectional view of a further embodiment of the correction device, again showing the essential portions thereof;

FIG. 20 is a perspective view, partly broken away, of another embodiment of the correction device in accordance with the invention, showing the essential portions thereof;

FIG. 21 is a sectional view of an embodiment of the invention in which the belt roller is supported by an automatic self-aligning bearing;

FIG. 22 is a perspective view of another embodiment of the invention belt deflection correction device;

FIG. 23 is a fragmentary front elevation view illustrating the manner in which one side edge of a deviated very wide belt comes into engagement with the corresponding belt deflection detection roller, in the device of FIG. 22;

FIG. 24 is a perspective view illustrating one form of support means for swingably supporting a belt roller;

FIGS. 25a, 25b and 250 are partial end elevation views showing the relative positions, in operation, of belt deflection detection rollers and belt roller push-out members of the device shown in FIG. 22;

FIGS. 26a and 26b are end elevation views illustrating one embodiment of braking means for the belt deflection detection rollers;

FIG. 27 is a partial plan view corresponding to FIG. 26b;

FIG. 28 is a side elevation view illustrating another embodiment of the braking means; and

FIG. 29 is a fragmentary side elevation view of yet another embodiment of a belt deflection correction device in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 2 through 5, in the embodiment of the invention therein illustrated, an endless belt 1, having a relatively small thickness and a relatively large width, is trained about a pair of

belt rollers

2 and 3 oriented substantially parallel to each other. Roller 2 is rotatably journalled in

bearings

5 and 6 secured to a base plate 4, and a pulley 8, on an endof shaft 7 supporting roller 2, is driven by an electric motor (not shown) for rotating roller 2 so as to move endless belt 1 in the direction of arrow a, illustrated in FIG. 5. The other roller 3 is journalled in

bearings

9a and 9b formed by bending opposite ends of a swinging member 9. A pivot shaft 10 is fixed centrally to swinging member 9 and is loosely supported in a bearing 11 on base plate 4.

A helical spring 13 embraces pivot shaft 10 between a disk or washer 12, secured to shaft 10 at its outer end, and bearing 11, so that member 9 is biased by spring 12 to move in a direction in which it pulls and tensions belt 1. The tension of endless belt 1 can be suitably adjusted by varying the resilience of spring 13 by adjusting a nut 14 threadedly mounted on the outer end of shaft 10, to move disk 12 along shaft 10.

A stop is formed by a flange bent out from the lower side edge of member 9 between pivot shaft 10 and bearing 9a, and this stop is biased by a spring 15, shown in FIG. 5, to press against the top end of a threaded rod 16. Rod 16 has its lower end portion formed with an external thread 16a which is engaged in an internally threaded member 18 secured to the forward end of a lower support arm 17, as shown in FIG. 3. The upper end portion of rod 16 extends loosely through an opening formed in the forward end portion of an upper supporting arm 19.

Support arms

17 and 19 have their base ends interconnected by two screws 20 and 21 extending through

respective slots

22 and 23 in base plate 4, so that plate 4 is positioned between

arms

17 and 19. Thus,

arms

17 and 19 can be adjusted along

slots

22 and 23 and, by varying the positions at which

arms

17 and 19 are mounted on plate 4, it is possible to vary the position of contact between rod 16 and stop 9c so as to thereby vary the angle of swinging of member 9 with respect to the amount of actual displacement of rod 16 when this rod is moved upwardly and downwardly as described hereinafter.

A rotation-transmission belt 24 is trained about a pulley 25, rotatably mounted between support arm 19 and base plate 4, and pulleys 26 and 27 rotatably mounted on base plate 4 through the medium of

respective pins

30 and 31. A frusto-conical detection roller 28 is fixed on pulley 26, and a similar detection roller 29 is fixed on pulley 27. These detection rollers are so disposed that their conical surfaces are spaced slightly apart from respective opposite side edges of endless belt 1. Stated another way, the conical surfaces of the two detection rollers are spaced apart a distance which is somewhat greater than the width of endless belt 1. Thus, when endless belt 1 moves along a normal path of movement between the

detection rollers

28 and 29, the opposite side edges of the belt do not engage these detection rollers.

However, if belt 1, moving in the direction of arrow a in FIG. 5 deviates from its normal path of movement in the direction of arrow b, a side edge la of belt 1 will engage the conical surface of detection roller 28 and frictionally effect rotation of roller 28 in the direction of the arrow indicated thereon. The rotation of detection roller 28 is transmitted to pulley through belt 24 so as to rotate threaded rod 16. Thread 16a has a direction such that, when rod 16a is rotated by detection roller 28, the rod is moved upwardly. Thus, when belt 1 deviates toward detection roller 28, the upper end of rod 16 moves stop 90 of member 9 upwardly so that member 9 is tilted against the bias of spring 15. Thereby, that end portion 3a of the supporting shaft of belt roller 3 disposed toward that side edge of belt 1 facing the direction of deflection is moved upwardly. As end portion 3a is moved upwardly, belt 1 begins to shift in a direction opposite to arrow b, thereby disengaging side edge la of belt 1 from detection roller 28 and, at the same time, arresting the movement of threaded rod 16.

If further shifting of belt 1 in a direction opposite to arrow b brings the other side edge lb of belt 1 into engagement with detection roller 29, the latter is rotated in the direction of the arrow thereon so that pulley 25 is rotated in a direction opposite to the arrow thereon and threaded rod 16 accordingly is moved downwardly. Consequently, member 9 is moved downwardly by spring 15, and end portion 3a of the supporting shaft of belt roller 3 is moved downwardly, thereby tilting belt roller 3 in a direction such that endless belt 1 shifts again in a direction of arrow b. It will be appreciated that the mounting member 9, pivoted by pivot shaft 10, oscillates under instructions" from detecting

rollers

28 and 29 to automatically and continuously correct deflection of endless belt 1 in either direction from its normal path of movement.

The described embodiment of the correction device is effective to correct deflection or deviation of endless belt 1 when its direction of movement is reversed so that it moves in a direction opposite to arrow a. In this case, the end portion of the supporting shaft of roller 3 nearer to that side edge 1a of belt 1 coming into contact with the detection roller, is moved downwardly and belt 1 shifts toward the higher portion of roller 3 which is consequently tilted.

By reducing as much as possible the frictional drag between the detection roller and the supporting shaft, as by using antifriction bearings and reducing the pitch of thread 16a of rod 16, it is possible to set member 9 smoothly in motion while endless belt 1 engages the detection rollers and drives the same with a small force.

It will be understood that the objective can be accomplished by using cylindrical detection rollers in place of the frusto-conical detection rollers described above. However, it will be seen that the surfaces of detection rollers which come into engagement with side edges of the endless belt preferably are conical in shape to attain optimum engagement between the side edges of the belt and the detection rollers, since the conical surfaces of the detection rollers :are compatible with the side edges of the belt as shown in FIG. 4 in dotted lines at la.

While the embodiment of the invention shown in FIGS. 2 through 5 utilizes an endless rotation-transmission belt, a linkage may be substituted for belt 24. Such a linkage arrangement, operating; as a rotation-transmission mechanism, is illustrated in FIGS. 6 and 9. In FIG. 6, a ring 41a is formed at the base end of a connecting rod 41, and fits loosely over an eccentric cylindrical member 43 fixed to or integral with the lower portion of a detection roller 42. A feed pawl 44, having arms 44a and 44b projecting in opposite directions, is pivotally connected, through the medium of a pin 45, to the forward end of connecting rod 41. The lower end of pin 45 is loosely received in a slot 47 formed in base plate 4, so that movement of connecting rod 41 is regulated by the cooperation between pin 45 and slot 47. The forward end of feed pawl 44 is spring biased, by a spring which has not been shown, to press against serrations of the outer periphery of a wheel 48 secured to threaded rod 16.

If side edge lb of belt 1 comes into engagement with detection roller 42, as viewed in FIG. 7, to rotate the detection roller, connecting rod 41 moves in crank motion to cause feed pawl 44, at its forward end, to rotate wheel 48 intermittently in the direction of the arrow, as shown in FIG. 6. The amount of eccentricity of cylindrical member 43 is such that wheel 48 is moved through a distance greater than the dimension of one tooth of the serration on its outer periphery as a result of one reciprocating movement of feed pawl 44. Arm 44a is arranged to abut against a pin 50 a little before pin 45 projects and reaches one limit of its range of movement. If pin 45 moves further in slot 47 thereafter, then feed pawl 44 pivots clockwise about pin 45 while arm 44a is maintained in contact with pin 50, so that feed pawl 44 is released from engagement with wheel 48.

A mechanism 52 similar to that just described is provided on the right side of wheel 48, and is arranged to rotate wheel 48 in a direction opposite to the arrow. A feed pawl 53 of mechanism 52 is disposed in spaced relation to wheel 48. Feed pawl 53 is adapted to pivot counterclockwise about a pin 56 when the latter reaches one limit of its range of movement and an arm of feed pawl 53 abuts a pin 55.

On the other hand, if pin 45 is pulled back to its other limit of movement in slot 47, feed pawl 44 pivots clockwise about pin 45 when arm 44b abuts against a pin 51, so that feed pawl 44 is released from engagement with wheel 48. Thus, when pin 45 reaches either of its two limits of movement in slot 47, or when connecting rod 41 is brought to a dead center position, feed pawl 44 is released from engagement with wheel 48 so that one feed pawl 44 inhibits the rotation of wheel 48 when the other feed pawl 53 is operative, and vice versa.

When connecting rod 41 is not in its dead center position, or when pin 45 remains stationary in an intermediate position in its range of movement, feed pawl 44 remains in engagement with wheel 48. When this is the case, if the other feed pawl 53 is rendered operative and rotates wheel 48 in a direction opposite to the direction of the arrow, then the serration of wheel 48 pushes and moves feed pawl 44 and causes eccentric cylindrical member 43 to rotate about a shaft 57 while connecting rod 41 is moved to a limit of this range of movement. This causes feed pawl 44, which has been maintained in engagement with wheel 48, to be released from such engagement so that wheel 48 can rotate freely without any interruption.

Pins

50, 51 and 55, as well as a pin 58 functioning in the same manner as pin 51, are all secured to base plate 46.

FIG. 8 illustrates the linkage, serving as a rotationtransmission mechanism, in which a shaft 62, supporting a detection roller 61, is disposed parallel to the belt supporting rollers. A lever 64 is pivotally supported by a pin 63 on the base plate, and has one end bent upwardly and formed with an elongated notch 65 loosely receiving therein an eccentric pin on the inner end of detection roller 61 and extending parallel to shaft 62. Accordingly, if detection roller 61 is rotated, lever 64 will oscillate and cause a feed pawl 66, pivotally mounted on the opposite end of lever 64 by a pin 67, to rotate wheel 48 intermittently in the direction of the arrow. Pins 69 and 70 on base plate 4 correspond to

pins

50 and 51 of FIG. 6, and act on feed pawl 68 in the same manner, so that explanation of the action of these pins is believed not necessary.

The movement of lever 64 in FIG. 8 is limited by pin 63 and eccentric pin 66, so that a guide slot, such as the slot 47 of FIG. 6, is not necessary. It will be understood that another mechanism, similar to the mechanism 71 shown in FIG. 8, is provided on the right side of wheel 48 as shown in FIG. 8.

It is possible to swing the member supporting belt roller 3 even if the pulley 25 of FIG. 2 is omitted, and such an arrangement is shown in FIG. 10. Referring to FIGS. l0, l1 and 12,

detection rollers

73 and 74, arranged at adjacent opposite side edges of belt 1, are connected to each other by an endless belt 75. One detection roller 73 is secured to a rod 76 having a threaded portion 76a threadedly engaged in an internally threaded member 77 on base plate 4, and the other detection roller 74 is rotatably mounted on a shaft 78 secured to base plate 4. With this arrangement, rod 76 is moved upwardly or downwardly when either

detection roller

73 or 74 is driven by endless belt 1. Thus, if a stop 72a of member 72 supporting belt roller 3 is caused to press against the upper end of threaded rod 76 by the bias of a spring 79, the axial vertical reciprocation of threaded rod 76 can be translated into swinging of member 72. Member 72 may be pivotally connected to base plate 4 by the same means as illustrated for member 9 shown in FIG. 3.

FIGS. 13 and 14 illustrate an embodiment of the invention wherein the rotation of

detection rollers

82 or 83 is transmitted to a threaded shaft 81, disposed parallel to the belt supporting rollers, which in turn displaces a movable cam member 84 threadedly engaged with a thread 81a of shaft 81, and having a cam surface 84a. Cam member 84 is moved parallel to shaft 81 so that a roller 85, pressing against cam surface 840, is moved upwardly and downwardly thereby imparting a swinging movement to member 86 which supports a belt supporting roller. A shaft 88 having detection roller 82 secured to its upper end is interconnected with shaft 81 by

helical gears

89 and 90 on respective shafts 88and 81 and a shaft 91 carrying a detection roller 83 is interconnected with shaft 81 by

helical gears

92 and 93. Cam member 84 is suitably supported for movement by threaded shaft 81 which is journalled by a bearing (not shown) secured by base plate 4.

FIG. 15 illustrates an embodiment of the belt correction deflection device in which

detection rollers

94 and 95 are supported by respective horizontally oriented shafts. Referring to FIG. 15, the detection rollers are rotatably supported by a base plate (not shown) and a gear 96, fixed to or integral with detection roller 94, transmits rotation of roller 94 through an intermediate gear 97 to a gear 99 secured to one end of a threaded shaft 98. A gear 100, fixed to or integral with detection roller 95, meshes directly with a gear secured on the other end of shaft 98. Thus, the direction in which threaded shaft 98 rotates, when roller 94 is driven by the endless belt moving in the direction of arrow a, is opposite to the direction in which shaft 98 rotates when detection roller 94 is driven byendless belt 1. Thus, it is possible to axially reciprocate a movable member 111 threadedly engaged with a thread 98a of shaft 98. Member 111 is secured to a shaft 112 mounting, at its forward end, a roller 113 pressing against a cam edge 114a on the underside of member 114 which supports an endless belt supporting roller. Member 114 may be pivoted, by a pivot shaft, on the base plate in the same manner as the member 9 shown in FIG. 5.

In the embodiment of the correction 'device shown in FIG. 16, one detection roller 116 is cooperable with a side edge 1a of the lower run of belt 1, and the other detection roller 117 is cooperable with a side edge 1c 7 of the upper run of belt 1. A pulley 118, fixed to or integral with detection roller 117, is connected by an endless belt 121 to a pulley secured to one end ofa threaded shaft 119, and detection roller 116 is secured to the opposite end of shaft 119. Shaft 119 has a thread 119a threadedly engaged with a movable member 122. Movable member 122 is provided with a cam member corresponding to the cam 84 of FIG. 13, or the roller 113 of FIG. 15, for imparting a swinging movement to one of the belt roller supporting members.

Referring now to the embodiment of the invention shown in FIG. 17, detection rollers and 126 are mounted on the outer ends of respective shafts 123 and 124, oriented parallel to the supporting rollers (not shown) for endless belt 1, and respective gears 127 and 128 are fixed on the inner ends of the shafts. Gears 127 and 128 mesh with a ring-type face gear 129 to transmit a swinging movement to a roller supporting member 131 through the medium of a cam 129a, formed on the underside of gear 129, and a lever 130.

Detection rollers

125 and 126 are rotatably supported by suitable bearings (not shown) secured on the base plate of the apparatus. If either detection roller is driven by a side edge 1a or 1b of endless belt 1, then the associated gear 127 or 128 causes gear 129 to rotate either clockwise or counterclockwise, and the rotation of gear 129,

through cam 129a, causes lever 130 to swing about a pivot shaft 132 so that its forward end 1300 imparts a swinging movement to member 131. Gear 129 may be suitably supported by a vertical shaft (not shown) connected to the base plate. Lever 130 is biased by a spring 133 to pivot counterclockwise about pivot shaft 132, so that a pin 134 secured to an end of lever 130 presses against cam 129a.

In FIG. 18,

pinions

137 and 138 fixed to or integral with respective detection rollers and 136 mesh with a gear 139, so that rotation of either detection roller is transmitted to gear 139. A swinging movement is imparted to a swinging member 141 pressing against a cam on the upper surface of gear 139. Gear 139 is rotatably supported by a shaft 142 secured to the base plate of the apparatus.

In FIG. 19,

detection rollers

145 and 146, supported by horizontal shafts rotatably supported on the base plate, are fixed to or integral with

respective gears

147 and 148 meshing with a face gear 144 having, on its upper surface, a cam 143 similar to the cam 140 shown in FIG. 18. 1

In all of the embodiments described above, the detection rollers are disposed between a pair of belt supporting rollers, such as the

rollers

2 and 3 of FIG. 2. However, the detection rollers may be rotatably mounted on the shaft supporting one belt roller, as shown in FIG. 20. Referring to FIG. 20, one belt roller 152, for an endless belt 151, is supported by a shaft 153 mounted in suitable bearings secured to a base plate (not shown). A detection roller 154 is rotatably mounted on shaft 153 adjacent one end of roller 152, and a detection roller 155 is rotatably mounted on shaft 153 adjacent the opposite end of roller 152. Both detection rollers, 154 and 155, are freely rotatable on shaft 153. The other belt roller 156supporting belt 151 is rotatably supported by a swinging member 157 supported on a pivot shaft 158 in the same manner as describe in connection with FIG. 2.

A roller 159, rotatably supported on a pin or the like connected to the lower edge of member 157, is biased by a spring 162 connected to member 157 to press against a cam surface a on the upper surface of movable cam member 160. Member 160 is threadedly engaged with a thread 163a of a threaded shaft 163 which has

pulleys

164 and 165 secured to its respective opposite ends. Pulley 164 is connected to a pulley portion of detection roller 154 by a cross belt 166, and pulley 165 is connected to a pulley portion of detection roller 155 by an open endless belt 167.

Assuming that endless belt 151, moving in the direction of the arrow, is deflected from its normal path of movement toward detection roller 154, so that the inner side edge 151a of belt 151 rides on roller 154, this roller will be driven by belt 151 and its rotation will be transmitted to pulley 164 through cross belt 166, so that shaft 163 'is rotated in one direction. Thread 163a of shaft 163 is so formed that, when detection roller 154 is driven by endless belt 151, member 160 moves in the direction of the arrow therebeneath. Consequently, when belt 151 is deflected toward roller 154, correction of the belt deflection iseffected by moving roller 159 upwardly by cam surface 160a. On the other hand, as detection roller 155 and pulley 165 are interconnected by belt 167, shaft 163 is rotated in the reverse direction when detection roller 155 is driven by endless belt 151, thereby moving member 160 in the direction opposite to the direction of the arrow. Thus,- deflection of belt 151 toward detection roller 155 is 5 corrected.

It will be understood that the diameter of the detection rollers may be made slightly larger than that of belt roller 152, that the detection rollers may have a frustoconical shape, or that the outer peripheral surfaces of the detection rollers may be knurled, in order to assure that endless belt 151 is brought into positive engagement with a respective detection rollers upon deflection from its normal path of movement.

In the embodiments hitherto described, the swingable belt roller is supported by a swinging support. However, if a belt roller is supported by an automatic self-aligning bearing 171, as shown in FIG. 21, the swinging support may be omitted. Bearing 171 includes an inner race secured to a shaft 174 in turn secured to

stationary side plates

172 and 173 at opposite ends thereof. Furthermore, bearing 171 includes an other race firmly fixed within belt roller I170.

Rollers

175 and 176, pressing against opposite ends of roller 170 from below, are supported by pivots on the respective opposite ends of a swingable member 177. Member 177 is pivoted on a stationary member by a shaft 178 at its mid portion, and has a portion disposed between pivot shaft 178 and roller 175 which is biased by a spring to press against the top end of a vertically reciprocable shaft 179 which is adapted to be axially reciprocated by two detection rollers. By moving shaft 179 upwardly and downwardly, a swinging movement is imparted to belt roller 170.

In the embodiment of the invention shown in FIG. 22,

side plates

202 and 203 are secured to a bottom plate 201, and shafts 204a and 2050 are rotatably supported by the lower portions of the side plates and rotatably

support belt rollers

204 and 205.

Pins

206 and 207 extend through the upper portions of respec hanger 212 is loosely supported by a pin 212a secured to the other end of lever 208, and another hanger 213 is loosely supported by a pin 213a secured to the other end of lever 209. A belt roller 214 is supported by

hangers

212 and 213 through the medium of a shaft 214a having its opposite ends extending through these hangers.

Levers

208 and 209 are biased by

springs

210 and 211 to pivot clockwise, as viewed in FIG. 2, about

respective pins

206 and 207, so that belt roller 214 is urged to move upwardly. An endless belt 215, having a relatively large width, is

trained'around belt rollers

204, 205 and 214, and tensioned by belt roller 214.

Shaft 214a of belt roller 214 has its opposite ends loosely received in cutouts 216a and 21Gb formed in opposed rising portions of a supporting member 216, shown more clearly in FIG. 24, which is swingably supported substantially at its central portion by a pivot shaft 217 secured to a support 218. Support218 is secured to a shaft 219 having its opposite ends secured to

side plates

202 and 203, so that belt roller 214 can swing in the direction in which belt 215 is deflected in order to restore belt 215 to its normal path of movement.

A gear 220 is secured to one end of shaft 204a supporting belt roller 204, and is driven by drive means (not shown) to rotate in the direction of arrow e. Belt roller 204 thus rotates in the direction of arrow e together with gear 20, so as to move belt 215 in the direction of arrowf.

Belt

deflection detection rollers

221 and 222 are rotatably mounted at the upper portions of

respective side plates

202 and 203 through the medium of

respective shafts

223 and 224, and are disposed on opposite sides of belt 215 near belt roller 214.

Detection rollers

221 and 222 are spaced axially from each other a distance slightly greater than the width of endless belt 215.

Rollers

221 and 222 are formed, at portions thereof corresponding to side edges of belt 215, with respective frustoconical surfaces 221a and 222a, with which the side edges of belt 215 are adapted to come into engagement when belt 215 is deflected from its normal path of movement.

Respective belt roller push-

back members

225 and 226 protrude radially from the cylindrical portions of

detection rollers

221 and 222, and are fixed to the associated detection roller or formed integrally therewith. If belt 215 is deflected from its normal path of movement and brought into engagement, at its side edge, with either frusto-conical surface 221a of roller 221 or frusto-conical surface 222a of roller 222, so that either

roller

221 or 222 is driven by belt 215, belt roller push-

back members

225 and 226 will rotate with the

respective rollers

221 and 222 and push backwardly the corresponding ends of belt roller 214. FIG. 23 shows belt 215 deflected toward side plate 203 and driving, by its side edge, frusto-conical surface 222a of detection roller 222.

Let it be assumed that belt roller 214 is disposed in a tilted position in FIG. 22, and in which its one end portion 214c is moved forwardly, in the direction of movement of belt 215 at the top of roller 214, or in which the other end portion 214b is disposed nearer than normal to detection roller 221, so that belt 215 moving on belt roller 214 is deflected toward side plate 202. In such case, endless belt 215, moving in the direction of arrow f, will soon begin to engage, at its side edge toward plate 202, the frusto-conical surface 2210 of belt deflection detection roller 221, as shown in FIG. 25a, and cause roller 221 to rotate in the direction of arrow g. At first, roller 221 rotates lightly in the direction of arrow g as the side edge of belt 215 comes into engagement with frusto-conical surface 221a. However, when belt roller push-back member 225 comes into contact with an end portion 214]; of roller 214, as shown in FIG. 25b, the frictional drag between roller 214 and member 225 causes member 225 to rotate at high speed, so that roller 221 also rotates at high speed in the same direction. Thus, end portion 214!) of belt roller 214 is pushed and moved by push-back member 225, so that belt roller 214 swings about supporting shaft 217 (FIG. 24), with supporting member 216, and shifts in a direction in which the end portion 214b moves away from roller 221, or in the direction of the arrow h in FIG. 250. The swinging and shifting movements of the belt roller 214 causes the end portion 214c of the roller 214 on the side of the side plate 203, shown in FIG. 22, to move toward the belt deflection detection roller 222. Thus, the belt 215 begins to move away from the detection roller 221 to the right in FIG. 22. If the side edge of belt 215 toward side plate 203 begins to drive detection roller 222, the same operation will be performed and belt roller 214 will begin to cause its end portion 214b to move toward roller 221. This cycle of operation is repeated during movement of endless belt 215, so that the deflection of belt 215 from its normal path of movement is corrected and the belt can move without deflection from its normal path.

Belt

deflection detection rollers

221 and 222 begin to rotate immediately as soon as they come into engagement with belt 215, so matter how small the force with which

belt

225 and 226 into abutting engagement with belt roller 214. The push-back members push back belt roller 214 by cooperation between these members and belt roller 214. The force with which belt 215 rubs against

rollers

221 and 222 does not have any direct relation in the action of moving back belt roller 214. After belt roller 214 is swung, and shifted in position, by either push-out member 225 or push-out member 226, belt 215 immediately begins to deviate in the opposite direction, so that the belt does not remain long in rubbing engagement with either

roller

225 or 226. Thus, this arrangement causes less wear and tear on the side edges of the very wide endless belt 215 than is caused by conventional correction devices.

In FIG. 22, resilient support members 227, only one of which is shown, are mounted on

side plates

202 and 203 at positions below the belt

deflection detection rollers

221 and 222. A respective brake member is secured to the free end of each support plate and is adapted to be urged, by the resilient force of the associated plate 227, to press against the peripheral surface of the

roller

221 or 222. Brake members 228 are intended to control the belt

deflection detection rollers

221 and 222 so that, after the belt roller 214 is moved by the push-

back members

225 and 226,

rollers

221 and 222 are prevented from continuing to rotate inertia or the like, and are simultaneously brought to positions in which they push against the belt roller.

The provision of brake members 227 is effective to assure that the

belt deflection rollers

221 and 222 are halted in good positions at all times, after moving back roller 214, no matter how high the speed of endless belt 215. The arrangement is also effective to prevent belt roller'214 from being repeatedly pushed back by

members

225 and 226.

FIGS. 26a and 26b illustrate another brake means for

detection rollers

221 and 222. In these figures, the brake means comprises brake belts 229 each secured at one end to the underside of a support 216 and, at the other end, to a fixed member S (only one brake belt being shown). With this brake means, belt deflection detection roller 222 can be controlled, when driven to rotate by the deflected endless belt 215, and belt roller 214 is pushed by belt roller push-out member 226 as shown in FIG. 26b, by brake belt 229 which is tensioned as belt roller 214 is moved backwardly. Thus,

rollers

221 and 222 can be brought to very good positions after belt roller 214 is moved backwardly, thereby permitting correction of the deflection of the endless belt 215 more accurately and smoothly. Furthermore,

as no brake is applied to

rollers

221 and 222 when belt deflection is initially detected,

rollers

221 and 222 can be driven by belt 215 with only a small force, thus eliminating the danger of damaging the side edges of belt 215. FIG. 27 illustrates a partial plan view of the arrangement shown in FIGS. 26a and 26b.

Another example of a brake means is illustrated in FIG. 28 as comprising plate-like brake members 317, each having a brake 317a and secured to the underside of a support 316. Each brake member 317 functions in the manner such that, when support member 316 moves to a dash-and-dot line position 316A, as belt deflection roller 222 is driven by belt 215 to rotate and belt roller 214 is pushed by push-back member 226 into a dash-and-dot line position 214A, brake 317a of brake member 317, which moves to a dash-and-dot line position 317a in slaved relation to support member 316, restrains push-out member 226. This causes member 226 to stop in a dash-and-dot line position 226A after member 226 has moved belt roller 214 backwardly. Thus, this brake means also can bring belt roller push-out

members

225 and 226 to good positions.

While brake belts 229 and brake members 317 have been described as being actuated directly as a result of the swinging and shifting in the position of belt roller 214, it is to be understood that the brake elements may be actuated indirectly, through a linkage or the like.

The belt roller push-back members described above have been formed coaxially and integrally with the belt deflection detection rollers, but the invention is not limited to this form of push-back members and the push-back members may be formed separately from the detection rollers as shown in FIG. 29. In FIG. 29, a large width endless belt 381, trained about a fixed driving belt roller 382 and a swingably supported belt roller 383, moves in the direction of the arrow 1'. A belt deflection detection roller 384 is disposed along the path of movement of belt 381 and connected, through an endless belt 385, to a belt roller push-back member 386 disposed above belt roller 383. Only one detection roller 384 is illustrated, but a second roller, similar in function and operation, is provided on the opposite side of the belt.

If belt 318 is deflected from its normal path of movement and moves into engagement with detection roller 384 for driving the same in the direction of the arrow j, push-back member 386 will be moved, simultaneously, in the direction of the arrow k, and belt roller 383 will move its end toward push-out member 386 nearer to this member. Accordingly, push-out member 386 pushes the end of belt roller 383, by its projecting pushout portion 386a, and moves belt roller 383 backwardly so as to cause belt 381 to shift in a correcting direction. In this way, the deflection of the wide endless belt can be prevented. In this embodiment, also, suitable brake means may be provided to apply a brake to deflection detection roller 384 or push-back member 386.

The belt deflection correction devices shown in FIGS. 22 and 29 are very simple in construction, and permit effecting swinging of the belt roller by the cooperative action ofthe push-back members and the belt roller itself. With this arrangement, the belt deflection detecting rollers can be driven by the wide endless belt with a very small force, so that less wear and tear is caused to the side edges of the belt and better and more accurate correction of belt deflection can be attained than is possible with conventional devices.

In the embodiments of the invention as described above, the wide endless belt is trained about two or three belt rollers. It is to be understood, however, that the invention is not limited to these particular numbers of belt rollers, and any suitable number of belt rollers may be used. If an exposure device is provided between

belt rollers

204 and 205, in the embodiment of FIG. 22, this can constitute an exposure section of a copying machine.

While specific embodiments oil the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be unt derstood that the invention may be embodied otherwise without departing from such principles.

What is claimed is;

l. A belt deflection correction device for a very wide endless belt trained over at least a pair of rollers, at least one of which is coupled to belt driving means, said device comprising, in combination, means mounting one of said rollers for swinging about a stationary pivot axis perpendicular to its axis of rotation; a pair of belt deflection detecting rollers rotatably mounted on immobile axes adjacent opposite side edges of said belt and spaced apart a distance slightly greater than the width of said belt so as normally to be out of engagement with the side edges of said belt; and means operatively connecting said detecting rollers to said one roller and operable, responsive solely to rotation of a detecting roller by engagement with a belt side edge as a result of belt deflection, to swing said one roller about said pivot axis in a direction to correct the belt deflection.

2. A belt deflection correction device, as claimed in claim 1, in which said means mounting one of said rollers comprises a bracket rotatably supporting said one roller and mounted for swinging about said pivot axis;

said connecting means connecting said detecting rollers to said bracket.

3. A belt deflection correction device, as claimed in claim 1, in which said means mounting one of said rollers comprises a shaft extending through said one roller; and a spherical antifriction bearing engaged between a mid portion of said shaft and a mid portion of said roller; said connecting means comprises a swingably mounted bracket having means at its opposite ends engaged with opposite ends of said one roller.

4. A belt deflection correction device, as claimed in claim 1, in which said connecting means comprises respective belt roller push-back. members rotatable with said belt deflection detecting rollers and operable, responsive to rotation of the associated detecting roller by engagement with a belt side edge, to engage said one belt-supporting roller to swing the latter about said pivot axis in a direction to correct the belt deflection.

5. A belt deflection correction device, as claimed in claim 4, including respective brake means each operatively associated with a belt deflection detecting roller.

6. A belt deflection correction device, as claimed in claim 5, in which each brake means is directly engageable with the associated deflection detecting roller.

7. A belt deflection correction device, as claimed in claim 6, in which each brake means comprises a brake band secured at one end to a fixed point and at the opposite end to the adjacent end of a roller supporting bracket constituting said mounting means; each brake band being tensioned, to engage the associated deflection detecting roller, responsive to engagement of the associated push-back member with said one belt supporting roller to swing the latter about said pivot axis in a direction to correct the belt deflection.

8. A belt deflection correction device, as claimed in claim 5, in which each brake means comprises a brake member secured to the adjacent end of a bracket supporting said one roller and swingable about said pivot axis; each brake member responsive to engagement of the associated push-back member with said one beltsupporting roller, to swing said one roller about said pivot axis, being moved to a position in which an end abutment thereof is in the path of movement of the associated push-back member.

claim 4, in which each belt roller push-back member is positioned adjacent said one belt-supporting roller and is rotatable about an axis spaced from the axis of rotation of the associated belt deflection detecting roller; and belt and pulley means interconnecting each belt deflection detecting roller to the associated push-back member.

10. A belt deflection correction device, as claimed in claim 1, including an axle fixed to rotate with said roller coupled to belt driving means; said belt deflection detecting rollers being mounted for free rotation on said axle each adjacent a respective opposite end of said roller coupled to belt driving means; said connecting means including transmission means connecting each belt deflection detecting roller to operating means engageable with said mounting means.

Claims

1. A belt deflection correction device for a very wide endless belt trained over at least a pair of rollers, at least one of which is coupled to belt driving means, said device comprising, in combination, means mounting one of said rollers for swinging about a stationary pivot axis perpendicular to its axis of rotation; a pair of belt deflection detecting rollers rotatably mounted on immobile axes adjacent opposite side edges of said belt and spaced apart a distance slightly greater than the width of said belt so as normally to be out of engagement with the side edges of said belt; and means operatively connecting said detecting rollers to said one roller and operable, responsive solely to rotation of a detecting roller by engagement with a belt side edge as a result of belt deflection, to swing said one roller about said pivot axis in a direction to correct the belt deflection.

2. A belt deflection correction device, as claimed in claim 1, in which said means mounting one of said rollers comprises a bracket rotatably supporting said one roller and mounted for swinging about said pivot axis; said connecting means connecting said detecting rollers to said bracket.

4. A belt deflection correction device, as claimed in claim 1, in which said connecting means comprises respective belt roller push-back members rotatable with said belt deflection detecting rollers and operable, responsive to rotation of the associated detecting roller by engagement with a belt side edge, to engage said one belt-supporting roller to swing the latter about said pivot axis in a direction to correct the belt deflection.

8. A belt deflection correction device, as claimed in claim 5, in which each brake means comprises a brake member secured to the adjacent end of a bracket supporting said one roller and swingable about said pivot axis; each brake member responsive to engagement of the associated push-back member with said one belt-supporting roller, to swing said one roller about said pivot axis, being moved to a position in which an end abutment thereof is in the path of movement of the associated push-back member.

9. A belt deflection correction device, as claimed in claim 4, in which each belt roller push-back member is positioned adjacent said one belt-supporting roller and is rotatable about an axis spaced from the axis of rotation of the associated belt deflection detecting roller; and belt and pulley means interconnecting each belt deflection detecting roller to the associated push-back member.