Rotor balancing structure, sheet material processing device, and image forming device

Information

  • Patent Grant
  • 6676317
  • Patent Number
    6,676,317
  • Date Filed
    Thursday, February 1, 2001
    23 years ago
  • Date Issued
    Tuesday, January 13, 2004
    20 years ago
Abstract
The drum has a balancer disposed at both ends of a drum body around which a printing plate is wound, and with a rotating shaft rotatably supported by a supporting plate via an elastic support member of a shaft receiving member. When the rotating drum is rotated in a state in which the rotating drum is out of balance, the elastic support member is elastically deformed so that the rotating shaft rotates integrally with the rotating drum. Balance of the drum is restored by eccentric revolution of the balancers, whereby the rotating drum is rotated around a center of the rotating shaft. A recording head is mounted at a bracket that moves integrally with the rotating drum. Thus, the recording head continually opposes a fixed position at the rotating drum, and an appropriate image can be formed on a printing plate.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a rotor balancing structure, a sheet material processing device, and an image forming device.




2. Description of the Related Art




There has been provided an image exposure device in which a light-sensitive printing plate (referred to as a “printing plate” hereinafter) having a light-sensitive layer formed on a sheet-type support such as thin aluminum is wound around a rotating drum, a light beam corresponding to image data is irradiated onto the printing plate while the rotating drum is being rotated at high speed (for example, 600 rpm or more), and the printing plate is thereby scanned and exposed.




In a case in which the printing plate has been wound around the rotating drum, sometimes, an unbalanced state in which the center of gravity of the rotating drum deviates from the center of rotation may occur. When the rotating drum is made to rotate at high speed in an unbalanced state, vibration occurring at the rotating drum may damage an image to be formed on the printing plate that has been wound around the rotating drum, and may furthermore produce noise or damage the interior of the device.




In order to prevent such an unbalanced state from occurring, there is provided a method in which, when the printing plate is wound around the rotating drum and attached thereto, balancing weights are mounted to the rotating drum. The balancing weight is mounted in such a way that the amount of unbalance, which is a displacement between the center of rotation of the rotating drum and the center of gravity thereof, is measured or calculated on the basis of a weight of the printing plate and a position at which the printing plate is mounted to the rotating drum. The weight of the balancing weight and the position at which the printing plate is mounted to the drum are calculated so as to correct the unbalanced state. On the basis of the calculation, a balancing weight may be mounted to the rotating drum, or the balancing weight which has already been mounted to the drum may be moved.




The size of the printing plate is determined so as to correspond to a size of prints. For this reason, a plurality of cassettes in which printing plates of different sizes are respectively accommodated are mounted at the image exposure device, a printing plate of a specified size is taken out from a corresponding cassette and is then mounted at the rotating drum.




If the size of the printing plate differs, the weight thereof changes. Further, the amount of unbalance when the printing plate is wound around the rotating drum changes in accordance with the size of the printing plate. At this time, when a size of the printing plate is input manually by an operator in order to balance the rotating drum, if the operator inputs a wrong printing plate size, the rotating drum is made to rotate in an unbalanced state, thus causing damage to the image exposure device or the like.




In order to prevent such damage to the image exposure device or the like due to the inputting of a wrong printing plate size, it might be thought that a sensor for detecting whether the rotating drum is rotating in an unbalanced state could be provided at the device, such that the rotation of the rotating drum is stopped immediately when the rotating drum has been judged by the sensor to be in an unbalanced state. However, were such a sensor to be provided, the interior of the device would become complicated.




On the other hand, there is also provided a method in which the size of the printing plate that has been wound around the rotating drum is detected by a sensor. However, in this case also, in order to provide the sensor for detecting the size of the printing plate, the interior of the device becomes complicated, and in addition to a sequence for adjusting the balancing weight, another sequence for detecting the size of the printing plate must be provided before the rotating drum rotates, thus becoming an obstacle to rapid exposure processing.




SUMMARY OF THE INVENTION




In view of the aforementioned facts, an object of the present invention is to provide a rotor balancing structure that can rotate and drive the rotor with an appropriate balance without using a sequence for correcting an unbalanced state of the rotor.




Further, it is another object of the present invention to provide a sheet material processing device and an image forming device that have been improved in the same manner as the rotor balancing structure.




In order to solve the aforementioned problems, there is provided a rotor balancing structure for rotating an object, the structure comprising: (a) a rotor to which an object can be removably fixed; (b) a support rotatably supporting the rotor and elastically supporting the rotor so that the rotor may be displaced in a radial direction thereof at the time that the rotor to which the object has been fixed is rotated; and (c) a balancer that can rotate together with the rotor and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall rotor including the object at the time that the rotor to which the object has been fixed is rotated can be obtained.




A sheet material processing device according to the present invention comprises: (a) a rotatable drum having an outer circumference around which a sheet material can be wound and fixed; (b) a driving device which rotates the drum when operated; (c) a support that can support a rotation of the drum and elastically support the drum so that the drum may be displaced in a radial direction thereof at the time that the drum around which the sheet material has been wound and fixed is rotated; (d) a balancer that can rotate together with the drum and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall drum including the sheet material at the time that the drum to which the sheet material has been wound and fixed is rotated can be obtained; and (e) a processing element for applying a predetermined processing to the sheet material on the outer circumference of the drum.




An image forming device according to the present invention comprises: (a) a rotatable drum having an outer circumference around which a printing plate can be wound; (b) a driving device which rotates the drum when operated; (c) a support that can support a rotation of the drum and elastically support the drum so that the drum may be displaced in a radial direction thereof at the time that the drum around which the printing plate has been wound is rotated; (d) a balancer which can rotate together with the drum and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall drum including the sheet material at the time that the drum to which the sheet material has been wound and fixed is rotated can be obtained; (e) a recording device for recording an image onto the printing plate at the outer circumference of the drum; and (f) wherein the driving device and/or the recording device, rather than rotating with the drum, are structured to be able to move in accordance with a displacement of the drum.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a schematic structural view of an image exposure device according to an embodiment of the present invention.





FIG. 2

is a schematic structural view of a recording section which is provided at the image exposure device.





FIG. 3

is a schematic perspective view illustrating a main portion of the recording section in which a rotating drum is mounted.





FIG. 4

is a schematic view illustrating a main portion of the recording section in which the rotating drum is mounted.





FIG. 5A

is a schematic perspective view of an end portion of a rotating drum, illustrating an example in which a balancer uses a ring-shaped balancing weight.





FIG. 5B

is a schematic perspective view of the balancer shown in

FIG. 5A

, as seen from an axial direction end side of the balancer.





FIG. 6

is a diagram illustrating an example of changes in amplitude and phase with respect to a rotational frequency of the rotating drum when the rotating drum according to the embodiment has become unbalanced.





FIG. 7A

is a schematic perspective view of an end portion of the rotating drum, illustrating an example in which the balancer uses a liquid weight.





FIG. 7B

is a schematic perspective view of the balancer shown in

FIG. 7A

, as seen from an axial direction end side of the balancer.





FIG. 8A

is a schematic perspective view of an end portion of the rotating drum, illustrating an example in which the balancer uses spherical balancing weights.





FIG. 8B

is a schematic perspective view of the balancer shown in

FIG. 8A

, as seen from an axial direction end side of the balancer.





FIG. 9

is a perspective view of a main portion of the recording section, illustrating another example in which the rotating drum is supported.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




With reference to the drawings, an embodiment of the present invention will be explained hereinafter.

FIG. 1

shows a schematic structure of an image exposure device


10


which is applied to the embodiment of the present invention. Using a light-sensitive planographic printing plate (hereinafter referred to as a “printing plate


12


”), in which a light-sensitive layer is formed on a thin (e.g., having a thickness of about 0.3 mm), rectangular support formed of, for example, aluminum, the image exposure device


10


irradiates onto the printing plate


12


a light beam modified on the basis of image data, whereby the printing plate


12


is scanned and exposed. The printing plate


12


, for which image exposure has been completed by the image exposure device


10


, is subjected to development processing or the like by an unillustrated automatic processor or the like.




In this image exposure device


10


, a cassette loading section


18


, a plate feeding and conveying section


20


, a recording section


22


, a discharge buffer section


24


, and the like are provided inside a machine casing


14


. The cassette loading section


18


is disposed at a lower right-hand side of

FIG. 1

inside the machine casing


14


. A plurality of cassettes


16


, each accommodating a large number of printing plates


12


, is loaded at a predetermined angle in a state in which the cassettes


16


are slanted in the cassette loading section


18


.




It is possible to process in the image exposure device


10


numerous-sized printing plates


12


having different vertical and horizontal dimensions. Printing plates


12


of whatever size are accommodated in the cassettes


16


such that the light-sensitive layers of the printing plates


12


face upward and an end thereof is positioned to correspond to a predetermined position. Further, the plurality of the cassettes


16


is loaded in the cassette loading section


18


so as to be spaced apart from each other at a predetermined distance and such that an end portion of the printing plate


12


accommodated in each cassette


16


reaches a substantially fixed height.




The plate feeding and conveying section


20


is disposed above the cassette mounting portion


18


, and the recording section


22


is disposed at a lower, central area within the image exposure device


10


, adjacent to the cassette loading section


18


. A pair of side plates


26


(only one of which is shown in

FIG. 1

) is provided at the plate feeding and conveying section


20


, and a reversal unit


28


and a sheet unit


30


are mounted to each of the pair of the side plates


26


.




The reversal unit


28


is provided with a reverse roller


32


having outer diameter of a predetermined dimension. A plurality of small rollers (for example, four small rollers


34


A,


34


B,


34


C and


34


D in the present embodiment) are provided around the reverse roller


32


. The small rollers


34


A to


34


D are disposed so as to straddle the reverse roller


32


from the cassette loading section


18


to the recording section


22


, and an endless conveying belt


36


is entrained around these small rollers


34


A to


34


D. Accordingly, the conveying belt


36


is entrained over the reverse roller


32


so that the conveying belt


36


stretches to roughly half the circumference of the reverse roller


32


between the small roller


34


A and the small roller


34


D.




A plurality of suction cups


38


which suck top ends of the printing plates


12


in the cassettes


16


are provided at the sheet unit


30


. The suction cups


38


are lowered to face the top ends of the printing plates


12


in the cassettes


16


loaded at the cassette loading section


18


, and suck the printing plate


12


. Further, at the sheet unit


30


, the suction cups


38


which have sucked the printing plate


12


are raised substantially upwardly so that leading ends of the printing plates


12


are pulled out from the cassette


16


and then inserted between the reverse roller


32


and the conveying belt


36


. Moreover, in

FIG. 1

, the moving position of the suction cups


38


is schematically illustrated by a double-dashed line.




At the reversal unit


28


, the reverse roller


32


and the conveying belt


36


are rotated in a direction in which the printing plate


12


is pulled out from the cassette


16


(in the direction of arrow A in FIG.


1


). Thus, the printing plate


12


is nipped between the reverse roller


32


and the conveying belt


36


, is pulled out from the cassette


16


, is curved while the printing plate


12


is wound around the circumferential surface of the reverse roller


32


, and then inverted. Further, a radius of the reverse roller


32


is of a dimension which prevents the printing plate


12


from failing or crimping when it is curved (e.g., 100 mm or more).




As shown by a solid line and the double-dashed line in

FIG. 1

, the side plates


26


move horizontally in accordance with the position of the cassette


16


from which the printing plate


12


is to be pulled out. Thus, the sheet unit


30


is moved together with the reversal unit


28


so that the suction cups


38


of the sheet unit


30


are made to face the printing plate


12


in the selected cassette


16


.




At the side plate


26


, a guide


40


is provided below the small roller


34


D. The printing plate


12


which has been inverted by the reverse roller


32


is passed between the reverse roller


32


at the small roller


34


D side and the conveying belt


36


, and fed to this guide


40


.




A conveyer


42


is disposed above the recording section


22


, and the printing plate


12


which has been fed out from the reversal unit


28


is guided by the guide


40


to the conveyer


42


. Further, the guide


40


swings in accordance with the movement of the side plate


26


such that the direction in which the printing plate


12


is guided is always directed to the conveyer


42


. The small roller


34


D at the recording section


22


side moves in accordance with the movement of the side plate


26


such that the direction in which the printing plate


12


is fed out from the reversal unit


28


is changed. Accordingly, the printing plate


12


which is fed out from the reversal unit


28


is gently curved by the guide


40


. Moreover, as the small roller


34


D moves, the small roller


34


C moves so as to apply a substantially fixed tension to the conveying belt


36


.




At the conveyer


42


, a conveying belt


48


is entrained between a roller


44


adjacent to an area beneath the plate feeding and conveying section


20


, and a roller


46


adjacent to the upper portion of the recording section


22


. The conveyer


42


is slanted such that the roller


46


is disposed lower than the roller


44


.




As shown in

FIGS. 1 and 2

, at the conveyer


42


, the roller


50


is disposed so as to face the roller


46


. The printing plate


12


which has been fed onto the conveyer


42


is conveyed along the conveying belt


48


, and is nipped into the roller


46


and the roller


50


.




A rotating drum


54


and a recording head


56


are mounted on a rack


52


at the recording section


22


. A puncher


58


is disposed above the rotating drum


54


. An opening


60


is formed at the puncher


58


.




The printing plate


12


which has been nipped by the rollers


46


and


50


is first fed by the conveyer


42


to the opening


60


of the puncher


58


, and the leading edge of the printing plate


12


is inserted into the opening


60


of the puncher


58


. When the printing plate


12


is inserted into the opening


60


, the puncher


58


is operated so as to form a positioning notch at a predetermined position of the leading edge of the printing plate


12


. Further, after forming of the notch by using the puncher


58


has been completed, the conveyer


42


is driven reversely, and the printing plate


12


is pulled out from the opening


60


of the puncher


58


.




At the conveyer


42


is provided an unillustrated swinging means. With the conveyer


42


at the roller


44


side as a shaft, the conveyer


42


at the roller


46


side is lowered by this swinging means toward the rotating drum


54


of the recording section


22


(which is shown by a double-dashed line in FIGS.


1


and


2


). Thus, the printing plate


12


at which the notch has been formed is fed to the recording section


22


in a state in which the leading edge thereof is directed to a predetermined position at the circumferential surface of the rotating drum


54


.




The rotating drum


54


provided at the recording section


22


is rotated in a direction in which the printing plate


12


is mounted and exposed (the direction of arrow B in FIGS.


1


and


2


), and in a direction in which the printing plate


12


is detached from the rotating drum


12


(the direction of arrow C in

FIGS. 1 and 2

) opposing the direction in which the printing plate


12


is mounted and exposed.




As shown in

FIG. 2

, a leading edge chuck


62


is mounted at a predetermined position of the outer circumferential surface of the rotating drum


54


provided at the recording section


22


. At the recording section


22


, when the printing plate


12


is mounted to the rotating drum


54


, the rotating drum


54


is stopped such that the leading edge chuck


62


is disposed at a position which opposes the leading edge of the printing plate


12


fed by the conveyer


42


(i.e., a position at which the printing plate is mounted to the rotating drum


54


).




At the recording section


22


, a mounting cam


64


is provided at the position at which the printing plate


12


is mounted to the rotating drum


54


so as to oppose the leading edge chuck


62


. The mounting cam


64


is rotated to press a portion of the leading edge chuck


62


at an end side thereof, and enables the printing plate


12


to be inserted between the leading edge chuck


62


and the circumferential surface of the rotating drum


54


.




The leading edge portion of the printing plate


12


that has been fed to the recording section


22


by the conveyer


42


is inserted between the leading edge chuck


62


and the circumferential surface of the drum


54


. In this state, as the mounting cam


64


is rotated, the leading edge of the printing plate


12


is nipped between the leading edge chuck


62


and the rotating drum


54


, and fixed to the rotating drum


54


. At this time, the printing plate


12


is positioned with respect to the rotating drum


54


by an unillustrated positioning pin which projects from the circumferential surface of the rotating drum


54


at a predetermined position thereof and which enters into the notch which has been formed by the puncher


58


.




In the recording section


22


, when the leading edge of the printing plate


12


is fixed to the rotating drum


54


, the rotating drum


54


is rotated in the direction in which the printing plate


12


is mounted and exposed. Thus, the printing plate


12


fed from the conveyer


42


is wound around the circumferential surface of the rotating drum


54


.




In the vicinity of the circumferential surface of the rotating drum


54


, a squeeze roller


66


is disposed at the downstream side of the mounting cam


64


in the direction in which the printing plate


12


is attached and exposed. When the printing plate


12


is wound around the rotating drum


54


, this squeeze roller


66


is moved toward the rotating drum


54


so that the printing plate


12


is nipped between the rotating drum


54


and the squeeze roller


66


. Thus, the printing plate


12


is kept in close contact with the circumferential surface of the rotating drum


54


.




Further, at the recording section


22


, a trailing edge chuck detachable unit


68


is disposed at the upstream side of the squeeze roller


66


in the direction in which the printing plate


12


is mounted and exposed. A detachable cam


70


is disposed at the downstream side of the squeeze roller


66


in the direction in which the printing plate


12


is mounted and exposed. At the trailing edge chuck detachable unit


68


, a trailing edge chuck


74


is disposed detachably at the tip end portion of a shaft


72


which moves toward the rotating drum


54


.




At the recording section


22


, when the trailing edge of the printing plate


12


which has been wound around the rotating drum


54


opposes the trailing edge chuck detachable unit


68


, the shaft


72


is projected so as to mount the trailing edge chuck


74


to the rotating drum


54


at a predetermined position thereof. Thus, the trailing edge of the printing plate


12


is nipped between the trailing edge chuck


74


and the rotating drum


54


and fixed thereto.




At the recording section


22


, when the leading edge and the trailing edge of the printing plate


12


are held at the rotating drum


54


, the squeeze roller


66


is made to separate from the drum


54


. While the rotating drum


54


is made to rotate at a predetermined high rotational speed, a light beam which has been modulated on the basis of image data is irradiated from the recording head


56


onto the printing plate


12


synchronously with the rotation of the rotating drum


54


, whereby the printing plate


12


is scanned and exposed in accordance with the image data.




At the recording section


22


, when scanning and exposure of the printing plate


12


have been completed, the rotating drum


54


is temporarily stopped by the trailing edge chuck


74


at a position where the trailing edge chuck


74


on the rotating drum


54


opposes the trailing edge chuck detachable unit


68


. Then, the trailing edge chuck


74


is detached from the rotating drum


54


so as to release the trailing edge of the printing plate


12


, and the printing plate is pressed by the squeeze roller


66


toward the rotating drum


54


. In this state, the rotating drum


54


is rotated in the direction in which the trailing edge chuck


74


is detached from the rotating drum


54


so that the printing plate


12


is fed out from the trailing edge side thereof to a discharge buffer section


24


.




Further, at the recording section


22


, when the leading edge chuck


62


reaches a position at which the leading chuck


62


opposes the detaching cam


70


and at which the printing plate


12


is detached from the rotating drum


54


, the rotating drum


54


is stopped, the leading edge chuck


62


is pressed by the detaching cam


70


so as to release the leading edge of the printing plate


12


.




As shown in

FIG. 1

, the discharge buffer section


24


is disposed above the squeeze roller


66


. This discharge buffer section


24


is provided with a discharge roller


78


disposed to an inner side of the discharge outlet


76


formed in the machine casing


14


. A plurality of small rollers (for example, small rollers


80


A,


80


B,


80


C,


80


D, and


80


E) is disposed around the discharge roller


78


. An endless conveying belt


82


is entrained around these small rollers


80


A to


80


E around the discharge roller


78


in a range of between about ½ to about ¾ the circumference of the discharge roller


78


.




The small roller


80


A is provided at the squeeze roller


66


side of the recording section


22


so as to face the roller


84


. The printing plate


12


which has been fed out from the recording section


22


is guided between the small roller


80


A and the roller


84


and nipped therebetween.




At the discharge buffer section


24


, the discharge roller


78


is driven to rotate in the direction in which the printing plate


12


is pulled out (in the direction of arrow D). Thus, the printing plate


12


which is nipped between the small roller


80


A and the roller


84


is pulled out from the recording section


22


and guided between the discharge roller


78


and the conveying belt


82


. Then, the printing plate


12


is nipped between the discharge roller


78


and the conveying belt


82


, and is wound around the discharge roller


78


. At this time, at the discharge buffer section


24


, the leading edge portion of the printing plate


12


(i.e., the printing plate


12


at the trailing edge side thereof which has been fed out from the recording section


22


) is nipped between the small roller


80


A and the roller


84


so that the printing plate


12


which has been wound around the discharge roller


78


is temporarily held.




As shown by the double-dashed line in

FIG. 1

, at the discharge buffer section


24


, the small roller


80


A and the roller


84


are moved to a position at which these rollers


80


A and


84


face the discharge outlet


76


. Thus, the leading edge of the printing plate


12


which has been wound around the discharge roller


78


is directed to the discharge outlet


76


. Further, the small roller


80


B which is provided above the small roller


80


A moves in accordance with the movement of the small roller


80


A, and applies a constant tension to the conveying belt


82


.




At the discharge buffer section


24


, when the leading edge of the printing plate


12


is directed to the discharge outlet


76


, the discharge roller


78


is rotated in the direction that the printing plate


12


is fed out (i.e., the opposite direction of arrow D) at a rotational speed that corresponds to the speed at which the printing plate


12


is conveyed at processing devices, such as an automatic processor and the like (not illustrated), provided adjacent to the discharge outlet


76


. Accordingly, the printing plate


12


is fed out from the discharge outlet


76


.




As shown in

FIGS. 3 and 4

, the rotating drum


54


provided at the recording section


22


has a drum body


90


. The drum body


90


is formed in a cylindrical shape and has an outer circumferential surface around which the printing plate


12


is wound. A balancer


100


is provided at each end of the drum body


90


in the axial direction thereof. Further, a rotating shaft


102


is provided at the rotating drum


54


so as to project from the balancer


100


. The rotating drum


54


is rotated integrally with the drum body


90


, the balancer


100


, and the rotational shaft


102


.




A pair of supporting plates


112


is provided on the rack


52


at a substantially 90° angle to the surface of the rack


52


with which the pair makes contact. As shown in

FIG. 4

, a shaft receiving member


114


(not shown in

FIG. 3

) is disposed coaxially with each of the pair of the supporting plates


112


. The tip end portion of the rotating shaft


102


is rotatably supported by the shaft receiving member


114


. Thus, the rotating drum


54


is supported at the rack


52


so as to be able to rotate freely.




At the shaft receiving member


114


which is mounted to the supporting plate


112


, an elastic support member


118


formed by an elastic body such as rubber is disposed by being inserted into a substantially cylindrical holder


116


. The rotating shaft


102


is passed through a shaft receiving member


136


provided at the axial center of the elastic support member


118


. The elastic support member


118


is deformed elastically so that the rotating drum


54


can move in accordance with the rotating shaft


102


in a radial direction thereof.




When a rotation of the rotating drum


54


is stopped or when it is not affected by a balance difference of the rotating drum


54


because the rotational speed is low, the elastic support member


118


does not deform elastically but supports the rotating drum


54


such that the axial center of the rotating drum


54


and that of the holder


116


correspond to each other.




Conversely, when the rotating drum


54


rotates at high speed (at about 600 rpm or more, for example, 1000 rpm) in an unbalanced state in which the center of gravity of the rotating drum


54


does not correspond to the center of the rotating shaft


102


, the elastic support member


118


deforms elastically in accordance with the change in centrifugal force transmitted from the rotating shaft


102


to the rotating drum


54


. Accordingly, the rotating shaft


102


can vibrate in a state in which the rotating shaft


102


is supported by the elastic support member


118


.




A bracket


104


is also disposed above the rack


52


between the pair of the supporting plates


112


. The bracket


104


is formed in a substantial U-shape by a pair of side plates


106


and a connecting plate


108


which connects the pair of the side plates


106


to each other.




As shown in

FIG. 4

, shaft receiving portions


110


are disposed coaxially with the pair of the side plates


106


. The rotating shaft


102


is passed through the shaft receiving portions


110


so as to be able to rotate relatively with respect to the shaft receiving portions


110


. Thus, when the rotating shaft


102


of the rotating drum


54


moves along a radial direction thereof, the bracket


104


moves integrally with the rotating shaft


102


. Further, the bracket


104


is supported by an unillustrated supporting means so as not to be affected by vibration or the like of the rotating drum


54


. The bracket


104


moves in accordance with the rotating shaft


102


in a state in which a rotation with the rotating shaft


102


as a center is inhibited.




As shown in

FIGS. 3 and 4

, a pulley


120


is mounted to at one side of the rotating shaft


102


between the supporting plate


112


and the side plate


106


of the bracket


104


. Further, a main scanning motor


122


is mounted to the connecting plate


108


of the bracket


104


. A pulley


124


is mounted to a driving shaft


122


A (see

FIG. 4

) of the main scanning motor


122


, and an endless timing belt


126


is entrained between the pulley


124


and the pulley


120


. Thus, the driving force of the main scanning motor


122


is transmitted to the rotating shaft


102


by way of the timing belt


126


, and the rotating drum


54


and the balancer


100


rotate with the rotating shaft


102


.




As shown in

FIG. 3

, head supports


128


are formed at the bracket


104


so as to extend outwardly from the side plates


106


in a radial direction of the rotating drum


54


. A pair of holders


132


are mounted respectively to ends of the head supports


128


. A pair of shafts


134


disposed parallel to the axis of the rotating drum


54


is mounted so as to be laid between the holders


132


.




The recording head


56


is mounted so as to span the shafts


134


, and is supported movably along the axial directions of the shafts


134


. Further, the recording head


56


is moved in a sub-scanning direction (i.e., the axial direction of each of the shafts


134


) by an unillustrated sub-scanning means. Moreover, the sub-scanning means may have an arbitrary structure. For example, a forwarding screw may be formed at one of the shafts


134


, a forwarding nut into which this forwarding screw is screwed may be rotated relatively with respect to the shaft


134


by a sub-scanning motor, so that the recording head


56


is moved in the sub-scanning direction. Alternatively, a moving mechanism independently of the shafts


134


can be provided so as to move the recording head


56


along the axial direction of the shaft


134


.




When the rotating shaft


102


has moved together with the rotating drum


54


while elastically deforming the elastic support member


118


, the recording head


56


, which is connected to the rotating shaft


102


through the bracket


104


, moves integrally with rotating drum


54


. Namely, the recording head


56


moves integrally with the rotating drum


54


in a state in which the recording head


56


always opposes a predetermined position at the circumferential surface of the rotating drum


54


.





FIGS. 5A and 5B

show a balancer


140


as an example of the balancer


100


. A balancing weight


142


formed in a ring-shape is provided at the outer circumference of the balancer


140


. Further, a diameter enlarging portion


144


is formed at the circumference of the rotating shaft


102


, and an elastic member


146


formed in a ring-shape is provided between the diameter enlarging portion


144


and the balancing weight


142


.




As shown by a solid line in

FIG. 5B

, the balancing weight


142


is ordinarily provided coaxially with the rotating shaft


102


by the elastic member


146


. The center of gravity Q of the balancing weight


142


, the axial center P


0


of the rotating shaft


102


, and the center of gravity P


s


of the rotating drum


54


correspond to one another. However, since the elastic member


146


elastically deforms, as shown by a double-dashed line in

FIG. 5B

, the center of gravity Q of the balancing weight


142


shifts with respect to the axial center P


0


of the rotating shaft


102


. Due to this shift in the center of gravity Q of the balancing weight


142


from the axial center P


0


of the rotating shaft


102


, the center of gravity P


s


of the rotating drum


54


shifts with respect to the axial center P


0


of the rotating shaft


102


.




The position of the center of gravity P


s


of the rotating drum


54


changes by the printing plate


12


being wound around the outer circumferential surface of the drum body


90


. In this state, the rotating drum


54


is rotated at high speed, and the rotating shaft


102


thereby vibrates inside the elastic support member


118


while elastically deforming the elastic support member


118


. At this time, at the balancer


140


, the balancing weight


142


rotates eccentrically while elastically deforming the elastic member


146


, and the center of gravity Q of the balancing weight


142


thereby moves in the direction in which a shift in the center of gravity P


s


of the rotating drum


54


is suppressed. Thus, the center of gravity P


s


of the rotating drum


54


is corresponded to the axial center P


0


of the rotating shaft


102


, and the rotating drum


54


thereby rotates around the axial center P


0


of the rotating shaft


102


.




An operation of the present invention will be explained hereinafter.




In the image exposure device


10


, image data to be exposed onto the printing plates


12


is input. The size and number of the printing plates


12


to be subjected to image exposure are set. When the order to initiate image exposure is given, image exposure processing of the printing plates


12


is initiated. Further, the image exposure device


10


may be one in which the processings are initiated by instructions given to the image processing device


10


by operation of a switch at an operation panel, and it may be one in which initiation of processing by the image exposure device


10


is ordered by a signal from an image processing device that outputs image data to the image processing device


10


.




When the image exposure device


10


is instructed to start processings, the printing plate


12


of a designated size is taken out from the cassette


16


by the reversal unit


28


and the sheet unit


30


. The printing plate


12


which has been taken out from the cassette


16


is fed to the conveyer


42


while being inverted. When the leading edge of the printing plate


12


which has been fed to the conveyer


42


is notched by the puncher


58


, the printing plate


12


is fed toward the circumferential surface of the rotating drum


54


of the recording section


22


.




At the recording section


22


, when the leading edge of the printing plate


12


is held at the rotating drum


54


by the leading edge chuck


62


and then wound around the circumferential surface of the rotating drum


54


, the trailing edge of the printing plate


12


is fixed to the rotating drum


54


by the trailing edge chuck


74


. Thereafter, at the recording section


22


, the printing plate


12


is scanned and exposed with a light beam irradiated from the recording head


56


, while the rotating drum


54


is rotated at a predetermined rotational speed.




The printing plate


12


, for which scanning and exposure have been completed, is fed out to the discharge buffer section


24


while being removed from the rotating drum


54


. Then, the printing plate


12


is fed at a predetermined speed from the discharge buffer section


24


to the discharge outlet


76


, and then discharged.




At the recording section


22


, when the printing plate


12


is wound around the drum body


90


of the rotating drum


54


and fixed thereto, the rotating drum


54


is rotated at high speed (e.g., 1000 rpm) by the driving of the main scanning motor


122


, and scanning and exposure of the printing plate


12


are carried out.




The center of gravity P


s


of the rotating drum


54


is moved by the printing plate


12


being wound around the drum body


90


, and a displacement is thereby caused between the axial center P


0


of the rotational shaft


102


and the center of gravity P


s


. The moving position of the center of gravity P


s


of the rotating drum


54


changes in accordance with the size of the printing plate


12


. The center of gravity P


s


of the rotating drum


54


is shifted from the axial center P


0


of the rotational shaft


102


so that the rotating drum


54


thereby becomes unbalanced.




When the main scanning motor


122


is driven and the rotating drum


54


in the unbalanced state is rotated, vibration is generated due to centrifugal force. At this time, since the rotating shaft


102


is supported via the elastic support member


118


, the rotating shaft


102


rotates integrally with the rotating drum


54


while elastically deforming the elastic support member


118


due to the centrifugal force from the rotating drum


54


.




As shown in

FIG. 6

, when a rotational frequency ω of the rotating drum


54


increases, a ratio (amplitude x/e) of a distance e (between the center of rotation of the rotating drum


54


and the center of the elastic support member


118


) to a distance×(between the center of rotation of the rotating drum


54


and the center of gravity of the rotating drum


54


) continues to increase until the ratio reaches an oscillating point (ω/ω


0


=1, however, ω


0


is a natural vibration of the elastic support member) between vibration of the rotating drum


54


and that of the elastic support member


118


.




A phase occurs between the vibration of the rotating drum


54


and the vibration (deformation) of the elastic support member


118


. This phase gradually expands in accordance with the increase in the rotational frequency ω of the rotating drum


54


.




When this rotational frequency ω of the rotating drum


54


exceeds the oscillating point, the amplitude x/e decreases gradually, and thereafter becomes fixed (which is x/e=1). Further, a phase δ between the vibration of the rotating drum


54


and the vibration of the elastic support member


118


forms an angle of 90° at the oscillating point. When the phase δ exceeds the oscillating point, the phase δ expands further as the rotational frequency ω increases, and then stabilizes with the amplitude x/e (the phase δ=180°).




Thus, when the rotating drum


54


reaches a predetermined rotational frequency ω


S


that is set to be sufficiently higher than the oscillating point, the rotating drum


54


is set in a state in which the rotation of the rotating drum


54


is fixed. Namely, at the recording section


22


, because the rotating shaft


102


of the rotating drum


54


is a so-called soft-type rotating shaft supported by the elastic support member


118


, when the rotating drum


54


reaches a predetermined rotational frequency ω


S


, the rotating drum


54


is kept in a state in which rotation thereof is stable.




At this time, the rotating drum


54


and the rotating shaft


102


rotate with the center of gravity P


s


of the rotating drum


54


as a center of rotation.




On the other hand, when the rotating drum


54


rotates in an unbalanced state, since the center of gravity Q of the balancing weight


142


is shifted from the center of rotation, the balancer


100


(


140


) provided at the rotating drum


54


rotates eccentrically. Thus, a centrifugal force is generated from the balancing weight


142


of the balancer


140


, and due to this centrifugal force, the balancing weight


142


moves while elastically deforming the elastic member


144


.




When the center of gravity Q of the balancing weight


142


is shifted from the center of rotation by the centrifugal force, the rotating drum


54


moves in the direction in which the center of gravity P


s


that is the rotation center of the rotating drum


54


corresponds to the axial center P


0


of the rotating shaft


102


.




The center of gravity P


s


of the rotating drum


54


is corresponded to the axial center P


0


of the rotating shaft


102


, and the rotating drum


54


thereby rotates with the axial center P


0


of the rotating shaft


102


as a center.




In this way, the assembly of the rotating drum


54


provided at the recording section


22


is simply structured such that the balancer


100


is mounted to the drum body


90


and the rotating shaft


102


is supported through the elastic support member


118


. Even when the rotating drum


54


becomes the unbalanced by the printing plate


12


being wound around the drum body


90


, the rotating drum


54


can be balanced by the rotating drum


54


rotating at a predetermined rotational frequency. As a result, it is possible to reliably prevent damage to the interior of the image exposure device resulting from unbalanced rotation of the rotating drum


54


.




Further, at the recording section


22


, regardless of the size of the printing plate


12


, the rotating drum


54


can be balanced merely by rotating the rotating drum


54


. Accordingly, for example, inputting the size of the printing plate


12


to be wound around the rotating drum


54


or providing a sensor for detecting a vibration which is generated when the wrong size of the printing plate


12


has been input becomes unnecessary. Further, providing a sensor or a sequence for detecting the size of the printing plate


12


which is wound around the rotating drum


54


, a sequence or a counter weight moving mechanism for balancing the rotating drum


54


in accordance with a detected size of the printing plate


12


, and the like become unnecessary.




Namely, at the recording section


22


, in order to appropriately balance the rotating drum


54


, there is no need to structure or process the circumferential edge portion of the rotating drum


54


in a complicated manner.




The main scanning motor


122


is mounted to the bracket


104


in which the rotating shaft


102


is passed through the shaft receiving portion


110


. Therefore, when the rotating shaft


102


moves integrally with the rotating drum


54


, the main scanning motor


122


also moves. Accordingly, a rotational force can reliably be transmitted to the rotating shaft


102


so that the rotating drum


54


can be rotated.




Further, since the bracket


104


is also provided with the recording head


56


, even when the center of rotation of the rotating drum


54


moves, the recording head


56


moves in accordance with the movement of the rotating drum


54


, and a state in which the recording head


56


always faces a fixed position of the drum body


90


is thereby maintained. Accordingly, when the rotating drum


54


has been balanced, if the rotating shaft


102


rotates at a position at which the rotating shaft


102


is shifted from the axial center of the shaft receiving member


114


, since the recording head


56


always faces a fixed position of the rotating drum


54


, it becomes possible to record an appropriate image in which a focal shift has not been caused at an appropriate position of the printing plate


12


.




The present embodiment has been explained by using, instead of the balancer


100


, the balancer


140


which is formed by the balancing weight


142


and the elastic member


146


which are ring-shaped. However, the balancer


100


can be structured arbitrarily provided that the balancer is a so-called auto-balancing mechanism in which, when the rotating drum


54


rotates in an unbalanced state, the rotating drum


54


can be balanced in accordance with a state of rotation of each of the rotating drum


54


and the rotating shaft


102


.





FIGS. 7A and 7B

, and

FIGS. 8A and 8B

show an example of a balancer, instead of the balancer


140


, which can be applied as the balancer


100


which is provided at the rotating drum


54


.




A balancer


150


shown in

FIGS. 7A and 7B

has a ring-shaped ring pipe


154


formed inside a rotor


152


which rotates integrally with the rotating shaft


102


. The ring pipe


154


is sealed, and accommodates therein a predetermined amount of a liquid weight


156


.




The liquid weight


156


has a volume of about ½ of that of the ring pipe


154


, for example, and is able to flow freely inside the ring pipe


154


. The center of gravity Q (not shown) moves due to the flow of this liquid weight


156


.




The rotating drum


54


having the balancer


150


as the balancer


100


becomes unbalanced by the printing plate


12


being wound around the drum body


90


, and rotates with the center of gravity P


s


thereof as a center, and thereby vibrates. At the balancer


150


, a centrifugal force acts upon the liquid weight


156


inside the ring pipe


154


. This centrifugal force is weighed eccentrically so as to move the center of the gravity P


s


of the rotating drum


54


toward the axial center P


0


of the rotation shaft


102


.




The rotating drum


54


, which has become unbalanced by the printing plate


12


being wound around the drum body


90


, reaches a predetermined rotational frequency so that the rotating drum


54


is balanced by the balancer


150


and thereby rotates.




A balancer


160


shown in

FIGS. 8A and 8B

has a ring pipe path


164


formed inside a rotor


162


which rotates integrally with the rotating shaft


102


. This ring pipe path


164


is formed coaxially with the rotating shaft


102


and has a plurality of spherical weights


166


stored therein. Each of the spherical weights


166


can move freely inside the ring pipe path


164


. The center of gravity Q of the balancer


160


moves in accordance with a position at which the weights


166


move.




The rotating drum


54


having the balancer


160


as the balancer


100


is set in the unbalanced state, and rotates with the center of gravity P


s


of the rotating drum


54


as a rotation center, and thereby vibrates. At the balancer


160


, a centrifugal force acts upon each of the spherical weights


166


inside the ring pipe


164


. The spherical weight


166


move in accordance with this centrifugal force. Due to this movement of the spherical weight


166


, the center of the gravity P


s


of the rotating drum


54


is moved toward the axial center P


0


of the rotation shaft


102


.




The rotating drum


54


, which has become unbalanced by the printing plate


12


being wound around the drum body


90


, reaches a predetermined rotational frequency, and the rotating drum


54


is balanced by the balancer


160


, and thereby rotates. Namely, the balancer


160


prevents the rotating drum


54


from vibrating, and the rotating drum


54


thereby rotates with the axial center P


0


as a center of rotation.




In this way, an arbitrary structure can be applied to the balancer


100


provided that the balancer


100


of the present invention has such an auto-balance mechanism that, when the rotating drum


54


has become unbalanced and rotates eccentrically, the balancer


100


is rotated integrally with the rotating drum


54


so that displacement of the rotational center of the rotating drum


54


is automatically corrected.




In the present embodiment, the shaft receiving member


114


having the elastic support member


118


has been mounted to the supporting plate


112


so as to rotatably support the rotating shaft


102


of the rotating drum


54


through this shaft receiving member


114


. However, the structure of the present invention is not limited to this.




For example, as shown in

FIG. 9

, instead of providing the shaft receiving member


114


at the supporting plate


112


, an auxiliary supporting plate


180


is disposed between the side plate


106


of the bracket


104


, and the supporting plate


112


. A pair of elastic support members


182


connect between the supporting plate


112


and the auxiliary supporting plate


180


. A pair of elastic support members


184


connect and support between the side plate


106


of the bracket


104


and the auxiliary supporting plate


180


.




Each of the elastic support members


182


and


184


is formed in a plate spring, for example. By the elastic support members


182


, both end portions of the auxiliary supporting plate


180


, which sandwich the rotating shaft


102


therebetween, in the vertical direction (the vertical direction of the page of

FIG. 9

) are connected respectively to the supporting plate


112


, and the auxiliary supporting plate


180


is thereby supported by the supporting plate


112


. Further, by the elastic support members


184


, both end portions of the auxiliary supporting plate


180


, which sandwich the rotating shaft


102


therebetween, in the transverse direction are connected respectively to the side plate


106


of the bracket


104


. Accordingly, the rotating drum


54


, together with the bracket


104


at which the recording head


56


and the main scanning motor


122


(none of them are shown in

FIG. 9

) are provided, are supported by the supporting plate


112


through the elastic support members


182


and


184


.




An elastic deformation of the elastic support member


182


enables the rotating drum


54


and the bracket


104


to move in the vertical direction thereof. Further, an elastic deformation of the elastic support member


184


enables the rotating drum


54


and the bracket


104


to move in the transverse direction thereof.




Thus, by supporting the rotating shaft


102


through the elastic support members


182


and


184


, a soft-type vibration preventing mechanism is thereby formed in which, when the rotating drum


54


has been rotated in an unbalanced state, due to elastic deformations of the elastic support members


182


and


184


, the rotating shaft


102


is able to move in a radial direction.




Accordingly, even when the rotating drum


54


has become unbalanced by the printing plate


12


being wound around the drum body


90


, the rotating drum


54


can be balanced by the elastic support members


182


and


184


and the balancer


100


, and thereby rotates.




In the present embodiment, an explanation has been given in which the present invention is used for the rotating drum


54


of the image exposure device


10


that scans and exposes the printing plate


12


. However, the present invention is not limited to this, and can be applied to image recording devices of various structures in which a sheet-type light-sensitive material such as a printing paper or a film is scanned and exposed by being wound around the rotating drum


54


.




As described above, the present invention has a simple structure such that a balancing means is provided at the drum body, the rotating shaft is supported rotatably through the elastic support member, and the rotating drum can be balanced so as to rotate in an stabilized state. As a result, an excellent effect can be obtained that sensors or complicated processings for balancing the rotating drum become unnecessary.




By moving a rotation driving means and an image recording means in accordance with the rotating shaft, a rotational force can be applied to the rotating shaft in a stable manner, and an image can be recorded at an appropriate position of the recording material.



Claims
  • 1. A rotor balancing structure for rotating an object, the structure comprising:(a) a rotor to which an object can be removably fixed; (b) a support rotatably supporting the rotor and elastically supporting the rotor so that the rotor may be displaced in a radial direction thereof at the time that the rotor to which the object has been fixed is rotated; and (c) a balancer that can rotate together with the rotor and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall rotor including the object at the time that the rotor to which the object has been fixed is rotated can be obtained.
  • 2. The rotor balancing structure according to claim 1, wherein the rotor is a drum that includes a drum body, the drum body having:a central longitudinal axis; an essentially cylindrical outer circumferential surface concentric to the axis; and shaft sections that are concentric to the axis, integrated with the drum body, and extend in relative directions from each longitudinal side of the drum body.
  • 3. The rotor balancing structure according to claim 2, wherein the support has an annular elastic body surrounding each shaft section for providing elastic radial displacement of the drum.
  • 4. The rotor balancing structure according to claim 2, wherein the balancer includes:an elastic member mounted to a shaft section; and an annular balancing weight elastically supported via the elastic member, with the elastic member and the balancing weight being rotatable together with the drum.
  • 5. The rotor balancing structure according to claim 2, wherein the balancer includes:a container mounted at the shaft section, the container being rotatable with the drum and having an annular passage; and a predetermined amount of fluid that is contained in the passage so as to be flowable within the passage.
  • 6. The rotor balancing structure according to claim 2, wherein the balancer includes:a container mounted at the shaft section, the container being rotatable with the drum and having an annular passage; and at least one weight movably accommodated within the passage.
  • 7. A sheet material processing device, comprising:(a) a rotatable drum having an outer circumference around which a sheet material can be wound and fixed; (b) a driving device which rotates the drum when operated; (c) a support that can support a rotation of the drum and elastically support the drum so that the drum may be displaced in a radial direction thereof at the time that the drum around which the sheet material has been wound and fixed is rotated; (d) a balancer that can rotate together with the drum and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall drum including the sheet material at the time that the drum to which the sheet material has been wound and fixed is rotated can be obtained; and (e) a processing element for applying a predetermined processing to the sheet material on the outer circumference of the drum.
  • 8. The device according to claim 7, wherein the processing element includes a recording head for recording an image onto the sheet material.
  • 9. The device according to claim 8, wherein the support has an annular elastic body surrounding each shaft section for providing elastic radial displacement of the drum.
  • 10. The device according to claim 8, wherein the balancer includes:an elastic member mounted to a shaft section; and an annular balancing weight elastically supported via the elastic member, with the elastic member and the balancing weight being rotatable together with the drum.
  • 11. The device according to claim 8, wherein the balancer includes:a container mounted at the shaft section, the container being rotatable with the drum and having an annular passage; and a predetermined amount of fluid that is contained in the passage so as to be flowable within the passage.
  • 12. The device according to claim 8, wherein the balancer includes:a container mounted at the shaft section, the container being rotatable with the drum and having an annular passage; and at least one weight movably accommodated within the passage.
  • 13. The device according to claim 7, wherein at least one of the processing element and the driving device is mounted to a bracket, and the bracket, rather than rotating with the drum, is connected to the drum so as to be able to move in accordance with a radial direction displacement of the drum.
  • 14. The device according to claim 7, wherein the processing element and the driving device are mounted to a same bracket, and the bracket, rather than rotating with the drum, is connected to the drum so as to be able to move in accordance with a radial direction displacement of the drum.
  • 15. The device according to claim 7, wherein the drum has a drum body, the drum body including:a central longitudinal axis; an essentially cylindrical outer circumferential surface concentric to the axis; and shaft sections that are concentric to the axis, integrated with the drum body, and extend in relative directions from each longitudinal side of the drum body.
  • 16. An image forming device, comprising:(a) a rotatable drum having an outer circumference around which a printing plate can be wound; (b) a driving device which rotates the drum when operated; (c) a support that can support a rotation of the drum and elastically support the drum so that the drum may be displaced in a radial direction thereof at the time that the drum around which the printing plate has been wound is rotated; (d) a balancer which can rotate together with the drum and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall drum including the sheet material at the time that the drum to which the sheet material has been wound and fixed is rotated can be obtained; (e) a recording device for recording an image onto the printing plate at the outer circumference of the drum; and (f) wherein the driving device and/or the recording device, rather than rotating with the drum, are structured to be able to move in accordance with a displacement of the drum.
  • 17. The device according to claim 16, wherein the drum has a drum body, the drum body including:a central longitudinal axis; an essentially cylindrical outer circumferential surface concentric to the axial center; and shaft sections which are concentric to the axis, integrated with the drum body, and extend in relative directions from each longitudinal side of the drum body.
  • 18. The device according to claim 17, wherein the balancer includes:an elastic member mounted to a shaft section; and an annular balancing weight elastically supported via the elastic member, with the elastic member and the balancing weight being rotatable together with the drum.
  • 19. The device according to claim 17, wherein the balancer includes:a container mounted at the shaft section, the container being rotatable with the drum and having an annular passage; and a predetermined amount of fluid that is contained in the passage so as to be flowable within the passage.
  • 20. The device according to claim 17, wherein the balancer includes:a container mounted at the shaft section, the container being rotatable with the drum and having an annular passage; and at least one weight movably accommodated within the passage.
Priority Claims (1)
Number Date Country Kind
2000-025326 Feb 2000 JP
US Referenced Citations (8)
Number Name Date Kind
4716761 Ito et al. Jan 1988 A
5099430 Hirsch Mar 1992 A
5162815 Hodge Nov 1992 A
5813346 Solomon Sep 1998 A
6204871 Keller et al. Mar 2001 B1
6283652 Sasaki et al. Sep 2001 B1
6505142 Inoue et al. Jan 2003 B1
6525754 Landolt Feb 2003 B2