Source: http://www.google.com/patents/US6164204?ie=ISO-8859-1
Timestamp: 2014-08-21 15:13:34
Document Index: 316365309

Matched Legal Cases: ['art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 20', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301', 'art 301']

Patent US6164204 - Drawing apparatus having fixing member for clamping material on drum and ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA recording drum has a clamp groove extending in its circumferential direction formed on its outer peripheral surface. A plurality of front end clamps are attached to the outer peripheral surface of the recording drum. Rear end clamps are attached so as to be movable and so as to be fixable along the...http://www.google.com/patents/US6164204?utm_source=gb-gplus-sharePatent US6164204 - Drawing apparatus having fixing member for clamping material on drum and method of mounting materialAdvanced Patent SearchPublication numberUS6164204 APublication typeGrantApplication numberUS 09/366,839Publication dateDec 26, 2000Filing dateAug 4, 1999Priority dateAug 4, 1998Fee statusPaidAlso published asUS6334392Publication number09366839, 366839, US 6164204 A, US 6164204A, US-A-6164204, US6164204 A, US6164204AInventorsToru Kawada, Shiro Kitawaki, Tadaaki Tani, Arifumi Omoto, Kazuma KanOriginal AssigneeDainippon Screen Mfg. Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (6), Referenced by (16), Classifications (21), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetDrawing apparatus having fixing member for clamping material on drum and method of mounting materialUS 6164204 AAbstract A recording drum has a clamp groove extending in its circumferential direction formed on its outer peripheral surface. A plurality of front end clamps are attached to the outer peripheral surface of the recording drum. Rear end clamps are attached so as to be movable and so as to be fixable along the clamp groove on the outer peripheral surface of the recording drum. A recording head is disposed ahead of the recording drum, and a clamp driving device is disposed behind the recording drum. The clamp driving device comprises a first driving device for fixing the front end clamps and fixing and releasing the rear end clamps and a second driving device for releasing the front end clamps. The front end clamps and the rear end clamps reliably fix a front end and a rear end of a plate to the outer peripheral surface of the recording drum by a reaction force produced by a spring and a centrifugal force produced by the rotation of the recording drum.
What is claimed is: 1. A drawing apparatus for drawing an image on a sheet-shaped recording material, comprising:a cylindrical drum having a rotary shaft and an outer peripheral surface and having a groove extending in the circumferential direction provided on said outer peripheral surface; a rotation driving device for rotating said drum around said rotary shaft; a fixing member provided so as to be attachable and detachable to or from said groove of said drum and so as to be movable along said groove for fixing the recording material to the outer peripheral surface of said drum; and a drawing unit for drawing an image on the recording material fixed on the outer peripheral surface of said drum, said fixing member comprising:a main body member having one side part and an other side part, the one side part for pressing one end of the recording material against the outer peripheral surface of said drum, and an engaging member provided so as to project on the side of a lower surface of said main body member and engaged with the inside of said groove of said drum, said drawing apparatus further comprising:a fixing member driving device for operating said engaging member of said fixing member to fix said fixing member to said drum or release said fixing member from said drum while holding said fixing member in a state where said engaging member of said fixing member is released from said groove of said drum. 2. The drawing apparatus according to claim 1, wherein said fixing member further includes urging means for urging the other side part of said main body member in the direction away from said outer peripheral surface of said drum.
3. The drawing apparatus according to claim 2, wherein a weight is provided in said other side part of said main body member.
4. The drawing apparatus according to claim 3, whereinsaid urging means comprises a spring provided between a lower surface of said other side part of said main body member and the outer peripheral surface of said drum, and said weight is a metal provided in said spring. 5. The drawing apparatus according to claim 2, wherein said urging means comprises a spring provided between the lower surface of said other side part of said main body member and the outer peripheral surface of said drum.
6. The drawing apparatus according to claim 1, wherein the length of said one side part of said main body member which is determined on the basis of said engaging member in the circumferential direction of said drum is smaller than the length of said other side part of said main body member.
7. The drawing apparatus according to claim 1, further comprising a moving mechanism for moving said fixing member driving device to a position spaced apart from the outer peripheral surface of said drum and a position in close proximity to the outer peripheral surface of said drum.
8. The drawing apparatus according to claim 1, wherein said engaging member is a rotating member provided so as to be rotatable in said main body member and fixed in said groove of said drum as it rotates.
9. The drawing apparatus according to claim 8, whereinsaid fixing member further comprises a sliding member provided in said main body member so as to be slidable in a predetermined direction for rotating said rotating member as it slides, and said fixing member driving device comprises a driving member engaged with said sliding member in said fixing member, and a driving member driving mechanism for moving said driving member in said predetermined direction. 10. The drawing apparatus according to claim 9, whereinsaid driving member driving mechanism comprises a moving member which together with said driving member, moves in said predetermined direction, and said fixing member driving device further comprises a holding member for holding or releasing said main body member of said fixing member as said moving member moves. 11. A drawing apparatus for drawing an image on a sheet-shaped recording material, comprising:a cylindrical drum having a rotary shaft and an outer peripheral surface; a rotation driving device for rotating said drum around said rotary shaft; a fixing member provided on the outer peripheral surface of said drum for fixing the recording material on the outer peripheral surface of said drum; a drawing unit for drawing an image on the recording material fixed on the outer peripheral surface of said drum; a first roller arranged along the outer peripheral surface of said drum parallel to the rotary shaft of said drum; a second roller arranged along said first roller; and a roller moving mechanism for moving said first roller to a position spaced apart from the outer peripheral surface of said drum and said second roller and a position in contact with the outer peripheral surface of said drum and said second roller. 12. A drawing apparatus for drawing an image on a sheet-shaped recording material, comprising:a cylindrical drum having a rotary shaft and an outer peripheral surface and having a groove extending in the circumferential direction provided on said outer peripheral surface; a rotation driving device for rotating said drum around said rotary shaft; a first fixing member provided on the outer peripheral surface of said drum for fixing one end of the recording material on the outer peripheral surface of said drum; a second fixing member provided so as to be attachable and detachable to or from said groove of said drum and so as to be movable along said groove for fixing an other end of the recording material on the outer peripheral surface of said drum; a drawing unit for drawing an image on the recording material fixed on the outer peripheral surface of said drum, a first roller arranged along the outer peripheral surface of said drum parallel to said rotary shaft of said drum; a second roller arranged along said first roller; and a roller moving mechanism for moving said first roller to a position spaced apart from the outer peripheral surface of said drum and said second roller and a position in contact with the outer peripheral surface of said drum and said second roller. 13. The drawing apparatus according to claim 12, wherein said second fixing member comprisesa main body member having one side part and an other side part, the one side part for pressing the other end of the recording material against the outer peripheral surface of said drum, an engaging member provided so as to project on the side of a lower surface of said main body member and engaged with the inside of said groove of said drum, and urging means for urging the other side part of said main body member in the direction away from the outer peripheral surface of said drum. 14. A drawing apparatus for drawing an image on a sheet-shaped recording material, comprising:a cylindrical drum having a rotary shaft and an outer peripheral surface with intermittent recess parts formed on said outer peripheral surface along the circumferential direction of said drum; a rotation driving device for rotating said drum around said rotary shaft; a fixing member detachably provided in an arbitrary one of said intermittent recess parts of said drum to be movable in the circumferential direction of said drum for fixing the recording material to the outer peripheral surface of said drum, and a drawing unit for drawing an image on the recording material fixed on the outer peripheral surface of said drum, said fixing member comprising:a main body member having one side part and an other side part, the one side part for pressing one end of the recording material against the outer peripheral surface of said drum, and an engaging member provided so as to project on the side of a lower surface of said main body member and engaged with an arbitrary one of said intermittent recess parts,said drawing apparatus further comprising: a fixing member driving device for operating said engaging member of said fixing member to fix said fixing member to said drum or release said fixing member from said drum while holding said fixing member in a state where said engaging member of said fixing member is released from said intermittent recess parts of said drum. 15. The drawing apparatus according to claim 14, wherein said fixing member further includes urging means for urging the other side part of said main body member in the direction away from said outer peripheral surface of said drum.
16. The drawing apparatus according to claim 15, wherein said engaging member is a rotating member provided so as to be rotatable in said main body member and fixed in said groove of said drum as it rotates.
17. The drawing apparatus according to claim 16, whereinsaid fixing member further comprises:a sliding member provided in said main body member so as to be slidable in a predetermined direction for rotating said rotating member as it slides, and said fixing member driving device comprises:a driving member engaged with said sliding member in said fixing member, and a driving member driving mechanism for moving said driving member in said predetermined direction. 18. The drawing apparatus according to claim 17, whereinsaid driving member driving mechanism comprises a moving member which together with said driving member, moves in said predetermined direction, and said fixing member driving device further comprises a holding member for holding or releasing said main body member of said fixing member as said moving member moves. 19. The drawing apparatus according to claim 14, wherein the length of said one side part of said main body member which is determined on the basis of said engaging member in the circumferential direction of said drum is smaller than the length of said other side part of said main body member.
20. The drawing apparatus according to claim 15, wherein a weight is provided in said other side part of said main body member.
21. The drawing apparatus according to claim 20, whereinsaid urging means comprises a spring provided between a lower surface of said other side part of said main body member and the outer peripheral surface of said drum, and said weight is a metal provided in said spring. 22. The drawing apparatus according to claim 15, whereinsaid urging means comprises a spring provided between the lower surface of said other side part of said main body member and the outer peripheral surface of said drum. 23. The drawing apparatus according to claim 14, further comprising a moving mechanism for moving said fixing member driving device to a position spaced apart from the outer peripheral surface of said drum and a position in close proximity to the outer peripheral surface of said drum.
24. A recording material mounting method in a drawing apparatus comprising:a cylindrical drum having a rotary shaft and an outer peripheral surface with a circumferentially extending groove formed on said outer peripheral surface; rotation driving device for rotating said drum around said rotary shaft; a front end clamp arranged on the surface of said film for pressing an end of said recording material against said outer peripheral surface of said drum; a drawing unit for drawing an image on a sheet-shaped recording material fixed onto said outer peripheral surface of said drum; a rear end clamp including a main body member having a side portion pressing the other end of said recording material against said outer peripheral surface of said drum and an engaging member provided to project on the side of the lower surface of said main body member and engaged in said groove of said drum; and rear end clamp holding means for holding said rear end clamp on a position separate from said drum, for mounting a recording material of an arbitrary size around said drum, said method comprising steps of: moving said recording material to a position where its font end reaches said front end clamp; fixing the front end of said recording material by said front end clamp; winding said recording material having the front end fixed by said front end clamp around said drum while rotating said drum at a low speed; moving said rear end clamp from said holding means to said groove around said drum for pressing the rear end of said recording material wound around said drum; and engaging said engaging member of said rear end clamp in said groove. 25. A recording material mounting method in a drawing apparatus comprising:a cylindrical drum having a rotary shaft and an outer peripheral surface with intermittent recess parts formed on said outer peripheral surface along the circumferential direction; rotation driving means for rotating said drum around said rotary shaft; a front end clamp arranged on the surface of said drum for pressing an end of said recording material against said outer peripheral surface of said drum; a drawing unit for drawing an image on a sheet-shaped recording material fixed onto said outer peripheral surface of said drum; a rear end clamp including a main body member having a side portion pressing the other end of said recording material against said outer peripheral surface of said drum and an engaging member provided to project on the side of the lower surface of said main body member and engaged in an arbitrary one of said intermittent recess parts of said drum; and rear end clamp holding means for holding said rear end clamp on a position separate from said drum, for mounting a recording material of an arbitrary size around said drum, said method comprising steps of: moving said recording material to a position where its front end reaches said front end clamp; fixing the front end of said recording material by said front end clamp; winding said recording material having the front end fixed by said front end clamp around said drum while rotating said drum at a low speed; moving said rear end clamp from said holding means to one of said intermittent recess parts for pressing the rear end of said recording material wound around said drum; and engaging said engaging member of said rear end clamp with said recess part. Description
The drawing apparatus may further comprise a strip-shaped lock plate provided in the groove of the drum, the spring member may urge the first and second lock members in the direction in which the lock portion of each of the first and second lock members is locked into the lock plate, and the first and second lock members may be provided such that the locking of the lock portion by the lock plate is released by the pressing of the press portion.
FIGS. 9(a) and 9(b) are is a cross-sectional views in a state before the rear end clamp is held in a first driving device in the drawing apparatus shown in FIG. 1 and a plan view of the rear end clamp;
FIGS. 10(a) and 10(b) are a cross-sectional views in a state where the rear end clamp is held in the first driving device in the drawing apparatus shown in FIG. 1 and a plan view of the rear end clamp;
FIGS. 19(a) and 19(b) are a cross-sectional views showing another example of the rear end clamp;
FIGS. 20(a) and 20(b) are a cross-sectional views showing still another example of the rear end clamp;
FIGS. 25(a) and 25(b) are side mainly showing a clamping mechanism of the rear end clamp in the drawing apparatus shown in FIG. 21;
FIGS. 30(a) and 30(b) are a cross-sectional view and a plan view respectively showing a state where the rear end clamp is held by the driving device in the drawing apparatus shown in FIG. 21;
FIGS. 31(a) and 31(b) are a cross-sectional view and a plan view respectively showing a state where a clamping mechanism of the rear end clamp is opened by the driving device in the drawing apparatus shown in FIG. 21;
FIGS. 32(a) and 32(b) are a cross-sectional view and a plan view respectively showing a state where the rear end clamp is detached from the driving device in the drawing apparatus shown in FIG. 21;
FIG. 34 is a perspective view of a recording drum in a conventional drawing apparatus.
In FIGS. 1 and 2, the drawing apparatus comprises a cylindrical recording drum 1. The recording drum 1 is rotated in a direction indicted by an arrow A (in a primary scanning direction) around a rotary shaft 1a by a rotation driving device 4. A plate 100 made of aluminum is mounted as a photosensitive material on an outer peripheral surface of the recording drum 1. One end of the plate 100 is fixed to the outer peripheral surface of the recording drum 1 by a plurality of front end clamps 2, and the other end of the plate 100 is fixed to the outer peripheral surface of the recording drum 1 by a plurality of rear end clamps 3.
The bearings 22 are fixed to the recording drum 1 by the bolts 23. The clamp main body 20 is attached to the bearings 22 so as to be rotatable by the rotary shaft 21. The pressing rubbers 26 are mounted on a lower surface of one side part 20a of the clamp main body 20. As shown in FIG. 5, a recess 12 is formed in the recording drum 1 below the other side part 20b of the clamp main body 20. The spring 25 is mounted between a lower surface of the other side part 20b of the clamp main body 20 and the recess 12 of the recording drum 1, and the metal ball 24 is inserted into the spring 25.
The lower surface of the one side part 20a of the clamp main body 20 may be coated with ceramic instead of mounting the pressing rubber 26 thereon. Consequently, the durability is improved without decreasing a frictional force.
The other side part 20b of the clamp main body 20 is urged in the direction away from the recording drum 1 centered around the rotary shaft 21, as indicated by an arrow P1, by a reaction force produced by the spring 25. Consequently, a force in the direction in which the one side part 20a of the clamp main body 20 is brought near the recording drum 1, as indicated by an arrow P2, so that one end of the plate 100 on the recording drum 1 is pressed by the pressing rubber 26.
The length L1 of the one side part 20a of the clamp main body 20 which is determined on the basis of the rotary shaft 21 is set to a length smaller than the length L2 of the other side part 20b of the clamp main body 20.
At the time of rotation of the recording drum 1, the metal ball 24 moves in the direction indicated by the arrow P1 by a centrifugal force, to push the other side part 20b of the clamp main body 20 up in the direction away from the recording drum 1. In addition, centrifugal forces are respectively exerted on the one side part 20a and the other side part 20b of the clamp main body 20. Since the length L1 of the one side part 20a of the clamp main body 20 is set to a length smaller than the length of the other side part 20b of the clamp main body 20, a rotation moment generated by the one side part 20a of the clamp main body 20 centered around the rotary shaft 21 is smaller than a rotation moment generated by the other side part 20b. Consequently, a force in the direction in which the other side part 20b of the clamp main body 20 is separated from the outer peripheral surface of the recording drum 1 is exerted, so that the one end of the plate 100 is firmly pressed against the outer peripheral surface of the recording drum 1 by the pressing rubber 26 in the one side part 20a of the clamp main body 20.
The higher the rotational speed of the recording drum 1 is, the larger a force exerted on the other side part 20b of the clamp main body 20 is, and the larger a force for the pressing rubber 26 in the one side part 20a of the clamp main body 20 to press the one end of the plate 100 against the outer peripheral surface of the recording drum 1 is. Even when the recording drum 1 is rotated at high speed, therefore, the one end of the plate 100 is reliably fixed to the outer peripheral surface of the recording drum 100 by the front end clamp 20, so that the plate 100 on the outer peripheral surface of the recording drum 1 is not shifted in position and detached.
FIG. 6 is an exploded perspective view of the rear end clamp 3, FIG. 7 is a partially sectional view along the length of the rear end clamp 3, and FIG. 8 is a cross-sectional view along the width of the rear end clamp 3.
The clamp bolt connecting plate 31 is provided so as to be slidable in a direction indicated by an arrow S in the three recesses 38, 39 upon penetrating side surfaces of the recesses 38, 39. The engaging member 32 is fixed to the clamp bolt connecting plate 31 in the recess 38. The driving pin 75 in the first driving device 7 is engaged with an engaging hole 32a of the engaging member 32. Long holes 31a are respectively formed in the vicinities of both ends of the clamp bolt connecting plate 31.
The second clamp bolts 34 have projections 34a projecting toward both their sides provided on their outer peripheral surfaces. The second clamp bolts 34 are inserted into holes 39a provided on the bottom surfaces of the recesses 39 of the clamp main body 30. The first clamp bolts 33 are attached to the heads of the second clamp bolts 34 by the screws 35. Projections 33a are provided on the lower surfaces of the first clamp bolts 33. The projections 33a of the first clamp bolts 33 are engaged with the long holes 31a of the clamp bolt connecting plate 31. Consequently, when the engaging member 32 slides in the direction indicated by the arrow S, the clamp bolt connecting plate 31, together with the engaging member 32, slides in the direction indicated by the arrow S, so that the first clamp bolts 33, together with the second clamp bolts 34, rotate in a direction indicated by an arrow Q.
As shown in FIG. 7, inner flanges 13 projecting inward are respectively provided at upper ends on both side surfaces of the clamp groove 11 formed in the recording drum 1. As shown in FIG. 7(a), when the projection portions 34a of the second clamp bolt 34 are positioned parallel to the clamp groove 11, the projection portions 34a are not engaged with the inner flanges 13 of the clamp groove 11. In this case, the rear end clamp 3 can be detached from the recording drum 1.
On the other hand, as shown in FIG. 7(b), when the projection portions 34a of the second clamp bolt 34 are positioned perpendicularly to the clamp groove 11 of the recording drum 1, the projection portions 34a are engaged with the inner flanges 13 of the clamp groove 11. Consequently, the rear end clamp 3 is fixed to the recording drum 1.
As shown in FIG. 8, the other end of the plate 100 is inserted between the lower surface of one side part 30a of the clamp main body 30 and the outer peripheral surface of the recording drum 1. A lead plate 42 is embedded in the other side part 30b of the clamp main body 30. In addition, the leaf spring 36 and the spring 37 are mounted on the lower surface of the other side part 30b of the clamp main body 30.
The other side part 30b of the clamp main body 30 is urged in the direction away from the recording drum 1 centered around the second clamp bolt 34, as indicated by an arrow Y1, by reaction forces produced by the leaf spring 36 and the spring 37. Consequently, a force in the direction in which the one side part 30a of the clamp main body 30 is brought near the recording drum 1, as indicated by an arrow Y2, so that the one end of the plate 100 on the recording drum 1 is pressed by the lower surface of the one side part 30a of the clamp main body 30.
The length L3 of the one side part 30a of the clamp main body which is determined on the basis of the second clamp bolt 34 is set to a length smaller than the length L4 of the other side part 30b of the clamp main body 30.
At the time of rotation of the recording drum 1, a centrifugal force is exerted in the direction indicated by the arrow Y1 on the lead plate 42 embedded in the lower surface of the other side part 30b of the clamp main body 30. In addition, centrifugal forces are respectively exerted on the one side part 30a and the other side part 30b of the clamp main body 30. Since the length L3 of the one side part 30a of the clamp main body 30 is set to a length smaller than the length L4 of the other side part 30b of the clamp main body 30, a rotation moment generated by the one side part 30a of the clamp main body 30 centered around the second clamp bolt 34 is smaller than a rotation moment generated by the other side part 30b. Consequently, a force in the direction in which the other side part 30b of the clamp main body 30 is separated from the outer peripheral surface of the recording drum 1 is exerted, so that the other end of the plate 100 is firmly pressed against the outer peripheral surface of the recording drum 1 by the one side part 30a of the clamp main body 30.
The higher the rotational speed of the recording drum 1 is, the larger a force to be exerted on the other side part 30b of the clamp main body 30 is, and the stronger a force for the one side part 30a of the clamp main body 30 to press the other end of the plate 100 against the outer peripheral surface of the recording drum 1 is. When the recording drum 1 is rotated at high speed, therefore, the other end of the plate 100 is reliably fixed to the outer peripheral surface of the recording drum 1 by the rear end clamp 3, so that the plate 100 on the outer peripheral surface of the recording drum 1 is not shifted in position and detached.
As shown in FIG. 9, the first driving device 7 is constituted by a driving device main body 70, a clamp bolt driving motor 71, a driving member 72, and position sensors 73. A gear 74 is attached to the clamp bolt driving motor 71. A plane gear 72a which is meshed with the gear 74 is provided on a side surface of the driving member 72. The driving member 72 is provided so as to be slidable in a direction indicated by an arrow U by the rotation of the clamp bolt driving motor 71. In addition, a driving pin 75 is provided at the center on the lower surface of the driving member 72, and holding pins 76 are respectively provided in the vicinities of both ends of the lower surface of the driving member 72. The position sensors 73 detect the position of the driving member 72.
In the state of in FIG. 9, when the first driving device 7 is brought near the rear end clamp 3, the driving pin 75 is inserted into an engaging hole 32a of an engaging member 32 in the rear end clamp 3, and the holding pins 76 are inserted into the circular parts of the holding holes 40 in the rear end clamp 3.
Thereafter, when the clamp bolt driving motor 71 rotates, the driving member 72 moves in a direction indicated by an arrow U1, so that the engaging member 32 which is engaged with the driving pin 75, together with a clamp bolt connecting plate 31, slides in the direction indicated by the arrow U1, as shown in FIG. 10. Consequently, the first clamp bolts 33, together with the second clamp bolts 34, rotate as shown by the arrows V1 and V2. In addition, the holding pins 76 move to the narrow parts of the holding holes 40 in the rear end clamp 3. Consequently, the rear end clamp 3 is held in the first driving device 7, and the projection portions 34a of the second clamp bolts 34 are brought into the state parallel to the clamp groove 11 of the recording drum 1, as shown in FIG. 7(a). In this state, the second clamp bolts 34 in the rear end clamp 3 can be inserted into the clamp groove 11 of the recording drum 1.
Subsequently, when the clamp bolt driving motor 71 rotates in the opposite direction, the engaging member 32 which is engaged with the driving pin 75, together with the clamp bolt connecting plate 31, slides in the opposite direction to the direction indicated by the arrow U1, so that the first clamp bolts 33, together with the second clamp bolts 34, rotate in the opposite direction. In addition, the holding pins 76 move to the circular parts of the holding holes 40 in the rear end clamp 3. Consequently, the projection portions 34a of the second clamp bolts 34 are brought into the state perpendicular to the clamp groove 11 of the recording drum 1, as shown in FIG. 7(b). As a result, the second clamp bolts 34 in the rear end clamp 3 can be fixed to the clamp groove 11 of the recording drum 1, and the first driving device 7 can be detached from the rear end clamp 3.
A gear 51 is attached to a clamp arm driving motor 50. The gear 51 is meshed with a gear 52, and an engaging portion 52a provided in the gear 52 is engaged with a long hole 6a of the clamp arm 6. The clamp arm driving motor 50 rotates, so that the clamp arm 6 swings in a direction indicted by an arrow C centered around a rotary shaft 61.
The second driving device 62 is constituted by a cam driving motor 63, gears 64a, 64b, 64c, 64d, and a cam 65. The gear 64a is attached to the cam driving motor 63. Torque generated by the cam driving motor 63 is transmitted to the gear 64d through the gears 64a, 64b, 64c. The cam 65 is attached to the gear 64d.
As shown in FIG. 11, the position of the clamp arm 6 in a state where the first driving device 7 is spaced apart from the outer peripheral surface of the recording drum 1 is referred to as an origin position, and the position of the clamp arm 6 in a state where the first driving device 7 is in close proximity to the outer peripheral surface of the recording drum 1 is referred to as a terminal position.
Next, the clamp bolt driving motor 71 in the first driving device 7 shown in FIG. 10 is then rotated, and the clamp bolt connecting plate 31 in the rear end clamp 3 is slid by the driving pin 75, to fix the second clamp bolts 34 in the clamp groove 11 of the recording drum 1 by the projection portions 34a, as shown in FIG. 7(b). Simultaneously, the holding pins 76 of the first driving device 7 shown in FIG. 10 move to the circular parts of the holding holes 40 in the rear end clamp 3, so that the rear end clamp 3 is released from the first driving device 7.
As shown in FIG. 10, the driving pin 75 of the first driving device 7 is inserted into the engaging hole 32a of the engaging member 32 in the rear end clamp 3, and the holding pins 76 are inserted into the holding holes 40 of the rear end clamp 3, so that the driving pin 75, together with the clamp bolt connecting plate 31, slides by the clamp bolt driving motor 71, and the second clamp bolts 34 rotate. Consequently, the second clamp bolts 34 are released from the clamp groove 11 of the recording drum 1. Simultaneously, the holding pins 76 of the first driving device 7 move to the narrow parts of the holding holes 40 of the rear end clamp 3. Consequently, the rear end clamp 3 is held by the first driving device 7.
FIG. 19 is a cross-sectional view showing another example of the rear end clamp 3. As shown in FIG. 19, an inner flange portion 13 projecting inward is provided at an upper end on one side surface of the clamp groove 11 formed in the recording drum 1. A second clamp bolt 34 in the rear end clamp 3 has a projection portion 34a projecting toward its one side part provided on its outer peripheral surface. The construction of the other portions in the rear end clamp 3 shown in FIG. 19 is the same as the construction of the rear end clamp shown in FIGS. 6 to 8.
When the projection portion 34a of the second clamp bolt 34 is positioned parallel to the clamp groove 11, as shown in FIG. 19(a), the projection portion 34a is not engaged with the inner flange portion 13 of the clamp groove 11. In this case, the rear end clamp 3 can be detached from the recording drum 1. On the other hand, when the projection portion 34a of the second clamp bolt 34 is positioned perpendicularly to the clamp groove 11 of the recording drum 1, as shown in FIG. 19(b), the projection portion 34a is engaged with the inner flange portion 13 of the clamp groove 11. Consequently, the rear end clamp 3 is fixed to the recording drum 1.
FIG. 20 is a cross-sectional view showing still another example of the rear end clamp 3. As shown in FIG. 20, the clamp groove 11 formed in the recording drum 1 has a rectangular cross section. An elliptical projection portion 34b is provided at a lower end of the second clamp bolt 34. The construction of the other portions in the rear end clamps 3 shown in FIG. 20 is the same as the construction of the rear end clamp 3 shown in FIGS. 6 to 8.
When the projection portion 34b of the second clamp bolt 34 is positioned parallel to the clamp groove 11, as shown in FIG. 20(a), the rear end clamp 3 can be detached from the recording drum 1. On the other hand, when the projection portion 34b of the second clamp bolt 34 is positioned perpendicularly to the clamp groove 11 of the recording drum 1, as shown in FIG. 20(b), both ends of the projection portion 34b are pressed against side surfaces of the clamp groove 11. Consequently, the rear end clamp 3 is fixed to the recording drum 1.
In FIGS. 21 and 22, the drawing apparatus comprises a cylindrical recording drum 1. The recording drum 1 is rotated in a direction indicted by an arrow A (in a primary scanning direction) around a rotary shaft 1a by a rotation driving device 4 shown in FIG. 22. A plate 100 made of aluminum is mounted as a photosensitive material on an outer peripheral surface of the recording drum 1. One end of the plate 100 is fixed to the outer peripheral surface of the recording drum 1 by a plurality of front end clamps 200, and the other end of the plate 100 is fixed to the outer peripheral surface of the recording drum 1 by a plurality of rear end clamps 300.
The clamp main body 301 is provided with a pair of holes 320. Holding holes 340 are respective provided in the vicinities of both ends of the clamp main body 301. The holding pins 760 of the driving device 700, described later, are respectively inserted into the holding holds 340.
Each clamping mechanism 302 is constituted by a pair of clamp members 321, 322, a shaft 323, a spring (not shown), a pair of pressing plates 324, 325, and four screws 326. The clamp members 321, 322 respectively have press portions 321a, 322a and hook portions 321b, 322b. The clamp members 321, 322 in each pair are connected to each other so as to be rotatable by the shaft 323, and are mounted in each hole 320 of the clamp main body 301. Each shaft 323 is held in the clamp main body 301 by the pair of pressing plates 324, 325 and the four screws 326.
The four double torsion springs 303 are attached to the rear surface of a side part 301b of the clamp main body 301. Each of the double torsion springs 303 is attached so as to be rotatable in a case 331 by a shaft 332, and the case 331 is fixed to the rear surface of the clamp main body 301 by four screws 333, 334.
As shown in FIG. 25, the clamp members 321, 322 in the clamping mechanism 302 are urged in the direction in which the hook portions 321b, 322b are closed inward centered around the shaft 323 by the spring 327. As shown in FIG. 25, the clamp groove 12 formed in the recording drum 1 is w-shaped in cross section, and can be formed at low cost by simple lathe forming.
Ends of the press portions 321a, 322a in a pair of clamp members 321, 322 are abutted against the upper surface of the clamp main body 301 from below. Consequently, a space between the hook portions 321b, 322b is slightly narrower than the lock plate 13 in the clamp groove 12 of the recording drum 1, as shown in FIG. 25(a).
When the press portions 321a, 322a in the clamp members 321, 322 are pressed downward by the driving pins 750 in the driving device 700, the hook portions 321b, 322b are opened outward, centered around the shaft 323, against a force produced by the spring 327, as shown in FIG. 25(b). In this state, the hook portions 321b, 322b can pass downward through both sides of the lock plate 13.
Thereafter, as shown in FIG. 25(c), when the clamp main body 301 is pushed downward, and the pressing of the press portions 321a, 322a by the driving pins 750 is released, the hook portions 321b, 322b are closed inward, centered around the shaft 323, by the spring 327. Consequently, the clamp members 321, 322 are engaged with the lock plate 13, and the rear end clamp 300 is fixed to the recording drum 301. Front ends of the hook portions 321b, 322b are firmly engaged with the lock plate 13 by the function of a centrifugal force exerted on the clamping mechanism 302 when the recording drum 1 is rotated at high speed. Therefore, the rear end clamp 300 can be firmly fixed to the recording drum 1.
In addition, in a system of inserting the clamp bolts 33, 34 into the clamp groove 11 and then rotating the clamp bolts, and engaging the projection portions 33a, 34a with the inner flanges of the clamp groove 11, as in the first embodiment, the thickness of the projection portions 33a, 34a (the length, in a direction perpendicular to the clamp groove 11, of the projection portions 33a, 34a before the rotation) is limited to the width of the clamp groove 11. On the other hand, in a system of simply opening or closing the hook portions 321b, 322b rightward or leftward, as in the second embodiment, the thickness of the hook portions 321b, 322b is the length thereof along the clamp groove 12, so that it can be determined irrespective of the width of the clamp groove 12. Therefore, the hook portions 321b, 322b can be caused to have such a thickness that it can withstand a larger clamping force.
As shown in FIG. 26, the one end of the plate 100 is interposed between a lower surface of the one side part 301a of the clamp main body 301 and the outer peripheral surface of the recording drum 1. The double torsion spring 303 is urged in a direction indicated by an arrow Y3.
The other side part 301b of the clamp main body 301 is urged in the direction away from the recording drum 1 centered around a position between the clamp members 321, 322, as indicated by an arrow Y1, by a reaction force produced by the double torsion spring 303. Consequently, a force in the direction in which the one side part 301a of the clamp main body 301 is brought near the recording drum 1, as indicated by an arrow Y2, is exerted, so that the one end of the plate 100 on the recording drum 1 is pressed by the lower surface of the one side part 301a of the clamp main body 301. The lower surface of the one side part 20a of the clamp main body 301 is coated with ceramic. Consequently, the durability is improved without decreasing a frictional force.
The length L3 of the one side part 301a of the clamp main body 301 which is determined on the basis of the position between the clamp members 321, 322 is set to a length smaller than the length L4 of the other side part 301b of the clamp main body 301.
At the time of rotation of the recording drum 1, centrifugal forces are respectively exerted on the one side part 301a and the other side part 301b of the clamp main body 301. Since the length L3 of the one side part 301a of the clamp main body 301 is set to a length smaller than the length L4 of the other side part 301b of the clamp main body 301, a rotation moment generated by the one side part 301a of the clamp main body 301 centered around the position between the clamp members 301, 302 is smaller than a rotation moment generated by the other side part 301b. Consequently, a force in the direction in which the other side part 301b of the clamp main body 301 is separated from the outer peripheral surface of the recording drum 1, so that the one end of the plate 100 is firmly pressed against the outer peripheral surface of the recording drum 1 by the one side part 301a of the clamp main body 301.
The higher the rotational speed of the recording drum 1 is, the larger a force to exert the other side part 301b of the clamp main body 301 is, and the stronger a force for the one side part 301a of the clamp main body 301 to press the one end of the plate 100 against the outer peripheral surface of the recording drum 1 is. Even when the recording drum 1 is rotated at high speed, therefore, the one end of the plate 100 is reliably fixed to the outer peripheral surface of the recording drum 1 by the rear end clamp 300, so that the plate 100 on the outer peripheral surface of the recording drum 1 is not shifted in position and detached.
Each bearing 751 is fixed on the bottom surface of the driving stay 720. One pair of driving pins 750 is respectively provided movably up and down so as to penetrate each bearing 751 and the driving stay 720. Each cam follower 752 is attached to upper ends of one pair of driving pins 750. The upper surface of the cam follower 752 is constituted by an upper horizontal surface 752a, an inclined surface 752b, and a lower horizontal surface 752c. Each cam 753 is attached to the slider 730 so as to be abutted against the upper surface of each cam follower 752. Each pair of driving pins 750 and each cam follower 752 are urged upward by a spring (not shown).
Holding members 722, 723 projecting downward are provided on the lower surface of the driving stay 720. A leaf spring 724 is attached to the holding member 723. The rear end clamp 300 shown in FIG. 24 is held between the holding member 722 and the leaf spring 724. In this case, the two holding pins 760 can be respectively inserted into the two holding holes 340 in the rear end clamp 300, and the two pairs of driving pins 750 can be respectively abutted against the press portions 321a, 322a of the clamp members 321, 322 in the two clamping mechanisms 302.
A position detecting member 735 horizontally projecting is provided at one end of the slider 730. Two tabs 735a, 735b are formed in the position detecting member 735. Two sensors 736, 737 for detecting the tabs 735a, 735b of the position detecting member 735 are provided in the driving stay 720. The position in the horizontal direction of the slider 730 with respect to the driving stay 720 is detected by the sensors 736, 737.
When the cam 753 in the slider 730 is positioned in the vicinity of a lower end of the inclined surface 752b of the cam follower 752, as shown in FIG. 27, front ends of the driving pins 750 are at a first vertical position V1, and the holding pin 760 is at a first horizontal position H1.
In this case, the driving pins 750 are not abutted against the press portions 321a, 322a of the clamp members 321, 322, as shown in FIG. 30. Consequently, the hook portions 321b, 322b of the clamp members 321, 322 are in a closed state. In addition, the holding pin 760 is positioned in a narrow part of the holding hole 340 in the rear end clamp 300. Consequently, the rear end clamp 300 is held by the holding pin 760.
In this case, the press portions 321a, 322a of the clamp members 321, 322 are pushed down by the driving pins 750, as shown in FIG. 31. Consequently, the hook portions 321b, 322b are opened outward, to pass through both sides of the lock plate 13 in the clamp groove 12. Further, the holding pin 760 moves to the vicinity of a boundary between the narrow part and the circular part of the holding hole 340 in the rear end clamp 300.
When the slider 730 further slides in the horizontal direction by the slider driving motor 740 so that the cam 753 is positioned on the upper horizontal surface 752a of the cam follower 752, as shown in FIG. 29, the front ends of the driving pins 750 are pushed down to a third vertical position V3, and the holding pin 760 moves to a third horizontal position H3.
In this case, the holding pin 760 moves to the circular part of the holding hole 340 in the rear end clamp 300, as shown in FIG. 32. When the driving device 700 is moved upward, the holding pin 760 is detached from the rear end clamp 300, and the pressing of the press portions 321a, 322a of the clamp members 321, 322 by the driving pins 750 is released. Consequently, the hook portions 321b, 322b of the clamp members 321, 322 are closed inward, and are engaged with the lock plate 13 in the clamp groove 12.
As shown in FIG. 33, recesses 15a, 15b are formed on both sides of a clamp groove 14 in a recording drum 1, and strip-shaped lock plates 16a, 16b are respectively attached on the recesses 15a, 15b. A clamping mechanism 360 comprises a pair of clamping members 361, 362. The clamp members 361, 362 respectively have press portions 361a, 362a and hook portions 361b, 362b.
The clamp members 361, 362 are respectively provided in the clamp main body so as to be rotatable by the shafts 363, 364, and are urged outward by a spring (not shown). Consequently, the hook portions 361b, 362b are respectively engaged with the lock plates 16a, 16b in the clamp groove 14. When the press portions 361a, 362a are pushed down by the driving pins 750 of the driving device 700, the engagement between the hook portions 361b, 362b and the lock plates 16a, 16b is released.
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