Sheet collecting apparatus and sheet collecting method

Abstract

In a sheet collecting apparatus having a collecting table on which a sheet charged by a charging means is collected, a suctioning/transporting means for suctioning and transporting the sheet charged by the charging means along a charging direction and releasing the sheet above the collecting table, back stoppers for receiving the sheet transported by the suctioning/transporting means downstream of the collecting table along a transport direction of the sheet, and a back guide disposed downstream of the collecting table along the transport direction of the sheet for regulating a position along the transport direction of the sheet received by the back stoppers, the sheet collecting apparatus positions the sheet charged by the charging means at a predetermined position and stacks it in a layer state.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2008-048522, the disclosures of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet collecting apparatus and a sheet collecting method.

2. Description of the Related Art

As disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2006-327713, there is a sheet collecting apparatus which has a back stopper for receiving a sheet charged by a charging means downstream of a collecting table and a sheet holding means for receiving the sheet above the collecting table, releases the sheet after it is received by the sheet holding means from the below, and drops the sheet onto the collecting table as a sheet collecting apparatus for collecting an planographic printing plate like a computer-to-plate (CTP) printing plate which has no slip sheet placed on the printing surface thereof and of which printing surface is liable to be scratched.

However, when the CTP printing surface is charged at a higher speed, the CTP printing surface may flutter because the kinetic energy of the charged CTP printing surface is not sufficiently absorbed by the back stopper. In this case, since the sheet holding means must wait while holding the CTP printing surface until fluttering of it is ceased, a pitch at which the CTP printing surface is collected cannot be increased so much.

If the CTP printing surface being held is released before fluttering thereof caused by the collision thereof against the back stopper is not completely ceased, since the CTP printing surface is collected on the collecting table before the kinetic energy is not completely released, there is a possibility that not only the CTP printing surface is not securely positioned on the sheet collecting table but also a scratch is generated to the periphery of the CTP printing surface.

SUMMARY OF THE INVENTION

An object of the invention, which was made to solve the above problem, is to provide a sheet collecting apparatus which does not generate a damage such as a scratch and the like on the sheet surface of a sheet such as a CTP printing plate of which surface is liable to be scratched even if the sheet is charged at a high charge speed without a protection member such as slip sheet at a high collection pitch.

A first aspect for solving the above problem relates to a sheet collecting apparatus for positioning a sheet charged by charging means at a predetermined position and stacking it in a layer state comprising: a collecting table on which the sheet charged by the charging means are collected; a suctioning/transporting means for suctioning and transporting the sheet charged by the charging means along a charging direction and releasing the sheet above the collecting table; back stoppers for receiving the sheet transported by the suctioning/transporting means downstream of the collecting table along a transport direction of the sheet; and a back guide disposed downstream of the collecting table along the transport direction of the sheet for regulating a position along the transport direction of the sheet received by the back stoppers.

In the sheet collecting apparatus of the first aspect, a sheet charged by the charging means is sucked and transported above the collecting table by the suctioning/transporting means and released therefrom above the collecting table.

Since the sheet released from the suctioning/transporting means is received by the back stoppers and the kinetic energy thereof is absorbed thereby, occurrence of fluttering of the sheet can be prevented. The sheet received by the back stoppers is collected on the collecting table in a state that the downstream side of the sheet in the charging direction is positioned by the back guide.

A second aspect for solving the above problem relates to the sheet collecting apparatus according to the first aspect having a pair of side guide members for regulating a charge path of the sheet transported by the suctioning/transporting means and released from the suctioning/transporting means above the collecting table.

In the sheet collecting apparatus of the second aspect, the sheet released from the suctioning/transporting means above the collecting table is received by the back stoppers in a state that the two sides of the sheet along the charging direction are positioned by the side guide members and collected on the collecting table in a state that the downstream side of the sheet in the charging direction is positioned by the back guide. Therefore, the sheet is collected in the state that the three sides in total of the sheet, i.e., the two sides along the charging direction and the downstream side in the charging direction are positioned.

According to the sheet collecting apparatus of the second aspect, the charged sheet is collected on the collecting table in the state that the three sides thereof are positioned by the side guide members and the back guide member as described above. Therefore, disturbance of a sheet on the collecting table can be more effectively reduced than a sheet collecting apparatus having no side guide members.

A third aspect for solving the above problem relates to the sheet collecting apparatus according to the second aspect including edge support members disposed so that they can appear or disappear from the side guide members and receiving the sheet from the below by projecting from the side guide members when the sheet is released from the suctioning/transporting means.

In the sheet collecting apparatus of the third aspect, when a sheet is released from the suctioning/transporting means, the edge support members project from the side guide members and hold the sheet from the below. By this operation, the sheet is dropped onto the collecting table in a state that the drop energy of the sheet is almost absorbed.

According to the third aspect, the sheet released from the suctioning/transporting means is held by the edge support members from the below and dropped onto the collecting table in the state that the drop energy thereof is almost absorbed as described above. Therefore, occurrence of a damage such as a scratch and the like on a sheet surface can be more effectively suppressed than a sheet collecting apparatus having no edge support members.

A fourth aspect for solving the above problem relates to the sheet collecting apparatus according to any of the first to third aspects comprising a front stopper disposed opposite to the back stoppers and the back guide member across the collecting table.

In the sheet collecting apparatus of the fourth aspect, a sheet released from the suctioning/transporting means above the collecting table is received by the back stoppers in a state that the two sides of the sheet along the charging direction are positioned by the side guide members and collected on the collecting table in a state that the side of the sheet downstream of a charge side is positioned by the back guide and the side of the sheet upstream in the charging direction is positioned by the front stopper.

According to the fourth aspect, the charged sheet is collected on the collecting table in the state that the four sides of the sheet, i.e., the two sides along the charging direction and the two sides downstream and upstream in the charging direction are positioned. Therefore, disturbance of a sheet bundle on the collecting table can be more effectively reduced than a sheet collecting apparatus having no front stopper.

A fifth aspect for achieving the above object relates to the sheet collecting apparatus according to any of the first to fourth aspects wherein the suctioning/transporting means include a breathable suction belt rotating in a predetermined direction and suction boxes disposed inside the suction belt for suctioning the sheet on the front surface of the suction belt by suctioning air through the suction belt.

In the sheet collecting apparatus of the fifth aspect, by suctioning the air in the suction boxes while rotating the suction belt so that the surface thereof facing the collecting table moves in the same direction as the charging direction a sheet charged by the charging means is sucked onto the outer surface of the suction conveyer and moved along the charging direction of the sheet. When the sheet moves above the collecting table, the sheet can be released from the front surface of the suction conveyer and dropped downward by supplying air into the suction boxes.

According to the fifth aspect, a timing at which a sheet is released from the suction conveyer can be set by setting timing at which a pressure reduced state is disrupted by supplying air into the suction boxes. Therefore, there is provided a sheet collecting apparatus wherein timing at which a charged sheet is released toward the collecting table can be easily set.

A sixth aspect for achieving the above object relates to the sheet collecting apparatus according to any of the first to fifth aspects wherein the back guide member is formed so as to have a sheet receiving height that is a height for receiving the sheet set higher than the lower edges of the back stoppers.

In the sheet collecting apparatus of the sixth aspect, since the side guide member is formed so that the sheet receiving height of the back guide is higher than the lower edges of the back stoppers, the sheet released from the suctioning/transporting means won't pass under the lower edges of the back stoppers because the height is regulated by the back guide.

According to the sixth aspect, a sheet released from the suctioning/transporting means is received at a position higher than the lower edges of the back stoppers in the back guide as described above. Therefore, the front edge of a sheet is effectively prevented from entering between the back stoppers and the back guide.

A seventh aspect for achieving the above object relates to the sheet collecting apparatus according to any of the second to sixth aspects wherein a sheet receiving height as a height for receiving the sheet by the back guide member is lower than a positioning height for positioning the sheet by the side guide members and the front stopper in.

In the sheet collecting apparatus of the seventh aspect, the sheet receiving height, which is the height in which a sheet is received by the back guide member, is lower than the position determination height in which the sheet is positioned by the side guides and the front stopper. Therefore, a sheet released from the suctioning/transporting means is at first received by the back stopper and is moved to the front stopper side. The upstream side of the sheet in the transport direction thereof is positioned by being butted against the portions of the positioning height of the side guides and then the two sides of the sheet along the transport direction are positioned by being butted against the portions of the side guides located at the positioning height thereof. Finally, the downstream side of the sheet in the transport direction is positioned by being butted against the portion of the side guide member located at the sheet receiving height thereof.

According to the seventh aspect, as described above, a sheet released from the suctioning/transporting means is positioned in the sequence of the side guides, the front stopper, and the back guide and finally collected on the collecting table in the state that all the four sides thereof are positioned. Therefore, since when the sheets are dropped after being held by the edge support member from the below, disturbance of sheets on the collecting table are more effectively suppressed, it can be more effectively prevented that the sheets are scratched by being rubbed with each other when they are dropped onto a collecting surface.

An eighth aspect for achieving the above object relates to the sheet collecting apparatus according to any of the first to seventh aspects having an auxiliary air nozzle that is disposed below the inlet side edge of the suctioning/transporting means from which the sheets are charged so as to lift the sheet sucked and transported by the suctioning/transporting means upward by jetting air upward.

In the sheet collecting apparatus of the eight aspect, a charged sheet can be pressed against the suctioning/transporting means by jetting air from the auxiliary air nozzle to the sheet.

According to the eighth aspect, since a charged sheet is caused to come into intimate contact with the suctioning/transporting means by jetting air from the auxiliary air nozzle, the sheet can be securely sucked to the suctioning/transporting means even if it is curved in the charging direction or a width direction.

A ninth aspect for achieving the above object relates to the sheet collecting apparatus according to any of the fourth to eighth aspects wherein the front stopper is formed such that the position thereof can be changed according to the measurement of a sheet to be charged in the charging direction thereof.

In the sheet collecting apparatus of the ninth aspect, when a sheet having a larger measurement in the charging direction is collected the front stopper is moved farther away from the back stoppers than in a case when a sheet having a smaller measurement in the charging direction is collected.

According to the ninth aspect, since the position of the front stopper is adjusted according to the measurement of a sheet in the charging direction, the relative positional relation of the sheet to the back stoppers when the sheet is released from the suctioning/transporting means can be kept constant at a time when a sheet having a large measurement in the charging direction is collected or at a time when a sheet having a small measurement in the charging direction is collected. Therefore, since a sheet can be collected while keeping a sheet separating condition in the suctioning/transporting means and timing at which the sheet is held from the below constant, a damage of the sheet due to disturbance of a sheet surface can be particularly effectively prevented.

A tenth aspect for achieving the above object relates to a method of collecting a sheet charged by a charging means along a predetermined direction in a layer state on a collecting table of a sheet collecting apparatus which has the collecting table, a suctioning/transporting means disposed above the collecting table, back stoppers disposed downstream of the collecting table along a transport direction of the sheets, and a back guide member disposed downstream of the collecting table along the transport direction of the sheet adjacent to the back stoppers, the method comprising a step of suctioning by the suctioning/transporting means the sheet charged by the charging means, transporting the sheet along the charging direction of the sheets, and releasing the sheet above the collecting table, a step of receiving the sheet released from the suctioning/transporting means downstream of the collecting table along the transport direction of the sheet by the back stoppers, and a step of regulating a position along the transport direction of the sheet, which is received by the back stoppers, by the back guide member.

In the sheet collecting method of the tenth aspect, a sheet charged by the charging means is sucked and transported above the collecting table by the suctioning/transporting means and released from the suctioning/transporting means above the collecting table.

Since the sheet released from the suctioning/transporting means is received by the back stoppers and the kinetic energy thereof is absorbed thereby, occurrence of fluttering of the sheet can be prevented. The sheet received by the back stoppers is collected on the collecting table by that the downstream side of the sheet in the charging direction is positioned by the back guide.

In the sheet collecting method of the tenth aspect, a sheet charged as described above is sucked and transported by the suctioning/transporting means, released therefrom above the collecting table, and collected on the collecting table while being positioned by the back guide after it is received by the back stoppers and the kinetic energy thereof is absorbed.

Accordingly, there can be provided a sheet collecting apparatus which can collect a sheet at a high collection pitch without causing a damage such as a scratch and the like on a sheet surface even when a sheet whose surface is liable to be damaged is collected without a protection member such as a slip sheet and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an overall arrangement of a sheet collecting apparatus according to a first exemplary embodiment.

FIG. 2 is a schematic plan view showing a relative positional relation among side guide members, edge support members, and back guide plates in the sheet collecting apparatus according to the first exemplary embodiment.

FIG. 3 is a schematic sectional view showing a relative positional relation when a collecting table, the side guide members, the edge support members, back stoppers, a front stopper, and a suction belt in the sheet collecting member according to the first exemplary embodiment are viewed from the side surfaces of them.

FIG. 4 is an enlarged view showing a detailed arrangement of suction conveyers in the sheet collecting apparatus according to the first exemplary embodiment.

FIG. 5 is an enlarged view showing another example of the suction conveyers in the sheet collecting apparatus according to the first exemplary embodiment.

FIG. 6 is an enlarged view showing still another example of the suction conveyers in the sheet collecting apparatus according to the first exemplary embodiment.

FIG. 7 is a partial sectional view showing a mechanism for causing the edge support members to appear or disappear with respect to the side guide members when it is viewed from above it.

FIG. 8 is a partial sectional view showing the mechanism for causing the edge support members to appear or disappear with respect to the side guide members when it is viewed from a side thereof.

FIG. 9 is a partial sectional view showing the mechanism for causing the edge support members to appear or disappear with respect to the side guide members when it is viewed forward of a direction in which an planographic printing plate is charged.

FIG. 10 is an enlarged sectional view showing a detailed arrangement of the back stoppers.

FIG. 11 is an explanatory view showing an operation of the sheet collecting apparatus according to the first exemplary embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. Exemplary Embodiment 1

An example of a sheet collecting apparatus of the present invention will be explained below.

[Arrangement]

As shown in FIG. 1, the sheet collecting apparatus 100 according to the exemplary embodiment 1 has a pair of back stoppers 4 for receiving an planographic printing plate P, which is charged by a belt conveyor 200 along the direction of an arrow ‘a’, by the front edges thereof, a collecting table 2 which is disposed upstream of the back stoppers 4 with respect to the charging direction ‘a’ of the planographic printing plate P, on which the planographic printing plate P received by the back stoppers 4 is collected, and which can be moved upward and downward by a lifter (not shown), a front stopper 6 located opposite to the back stoppers 4 across the collecting table 2, and a pair of side guide members 8 which are disposed on both the side edges of the collecting table 2 along the charging direction ‘a’ and guide the planographic printing plate P charged onto the collecting table 2 from both the sides thereof.

The sheet collecting apparatus 100 further has back guide plates 1 as an example of a back guide member of the invention. The back guide plates 1 are disposed at positions where they confront the front stopper 6 across the collecting table 2 on both the sides of the back stoppers 4 when viewed from the charging direction ‘a’. The planographic printing plate P is an example of a sheet collected on the sheet collecting apparatus of the invention and placed on the uppermost surface of an planographic printing plate bundle 50 which has been collected on the collecting table 2, i, e., on a sheet collecting surface 51.

A pair of suction conveyers 10 are disposed in the vicinity of side guide members 8 located above the collecting table 2.

Further, as shown in FIG. 3, an auxiliary air nozzle 7 is disposed upstream of the front stopper 6 with respect to the charging direction ‘a’ to eject air upward.

As shown in FIGS. 1 and 2, each of the side guide members 8 has a vertical portion 8A that is orthogonal to a collection surface 2A of the collecting table 2 on which the planographic printing plate P is collected and a tilt portion 8B extending upward of the vertical portion 8A and tilting to the outside. The distance between the right and left side guide members 8 is preferably 0.2 to 1 mm larger than the measurement of the planographic printing plate P in the width direction thereof, i.e., the measurement thereof in the direction orthogonal to the charging direction ‘a’.

The vertical portion 8A of each side guide member 8 has four laterally long rectangular openings 80 formed therethrough, and edge support plates 9 are disposed to the openings 80 so as to appear or disappear therefrom so that they hold the charged planographic printing plate P from the below. As shown in FIG. 2, the edge support plates 9 hold the planographic printing plate P in the state that they project from the openings 80. The edge support plates 9 project from the vertical portions 8A preferably in the amount of about 5 to 50 mm. Further, as shown in FIG. 3, a sheet receiving height H₄, which is a height at which the edge support plates 9 receive a sheet, is preferably set to about 50 mm from the collecting table 2. Further, the distance H₅ from the suction conveyer 10 to the edge support plates 9 in the height direction thereof is preferably set to about 150 to 200 mm from the viewpoint of preventing an planographic printing plate P charged by the suction conveyer 10 later coming into contact with an planographic printing plate P charged previously.

As shown in FIG. 3, each of the back guide plates 1 is formed so that a height H_bg that is a height from the collecting table 2 to the top of the back guide plate 1 is larger than a height H_bp that is a height of the lower edges of the back stoppers 4. The back guide plate 1 has a vertical portion 1A orthogonal to the collection surface 2A and a curved portion 1B disposed on top of the vertical portion 1A and curved downstream along the charging direction ‘a’.

Further, as shown in FIG. 3, the front stopper 6 also has a vertical portion 6A orthogonal to the collection surface 2A and a curved portion 6B located on top of the vertical portion 6A. However, the curved portion 6B of the front stopper 6 curves upstream in the charging direction ‘a’. Note that when the planographic printing plate P, which is intended to be charged, has a large measurement along the charging direction ‘a’, the front stopper 6 can preferably move upstream along the charging direction ‘a’, and when the planographic printing plate P has a small measurement, the front stopper 6 can preferably move downstream along the charging direction ‘a’.

The back guide plates 1 guide the planographic printing plate P by the curved portions 1B and receive it by the vertical portions 1A. Accordingly, as shown in FIG. 3, the sheet receiving height H₁ of the back guide plate 1 is the height of the boundary portion between the vertical portion 1A and the curved portion 1B. Likewise, the front stopper 6 and the side guide members 8 also guide the planographic printing plate P by the curved portion 6B and the tilt portions 8B and position it by the vertical portion 6A and the vertical portions 8A. Accordingly, as shown in FIG. 3, the positioning height H₂ of the front stopper 6 is the height of the boundary between the vertical portion 6A and the curved portion 6B, and the positioning height H₃ of the side guide member 8 is the height of the boundary between the vertical portion 8A and the tilt portion 8B.

As shown in FIG. 3, the back side plates 1, the front stopper 6, and the side guide members 8 are formed such that the sheet receiving height H₁ of the back guide plates 1 is lower than any of the positioning height H₂ of the front stopper 6 and the positioning height H₃ of the side guide members 8 and the positioning height H₃ of the side guide members 8 is lower than the positioning height H₂ the front stopper 6. Note that the distance from the front stopper 6 to the back guide plates 1 is preferably about 0.05 to 1 mm larger than the measurement of the planographic printing plate P along the charging direction ‘a’.

The back guide plate 1 is composed of a metal sheet by which the vertical portion 1A and the curved portion 1B are constituted integrally. However, the curved portion 1B may be formed of a resin material of various resins, an elastomer material such as vulcanized gum or non-vulcanized gum, or a soft material such as a soft vinyl chloride resin in place of that it is formed of metal, and it may be covered with the soft material. When the curved portion 1B is formed of or covered with the resin material and the soft material, it can more effectively prevent that the planographic printing plate P is damaged by coming into contact with the back guide plate 1 as compared with the case that the curved portion 1B is composed of the metal sheet and conveyed.

The front stopper 6 is composed of a metal sheet which has a curved upper edge and forms the vertical portion 6A and the curved portion 6B integrally.

As shown in FIGS. 1 and 4, the suction conveyer 10 has a suction belt 11, which is an endless belt having a lot of suction holes 11A formed on the entire surface thereof, a pair of drive rollers 12 around which the suction belt 11 is stretched and which drives the suction belt 11, and suction boxes 13 disposed in a row inside the suction belt 11. The suction belt 11 is stretched such that the inner surface thereof slides on the lower surfaces of the suction boxes 13, and a predetermined number of communication holes are formed on the lower surfaces of the suction boxes 13.

As shown in FIG. 4, the suction boxes 13 has a suction line 15 connected thereto for suctioning air from inside thereof and a discharging line 16 connected thereto for supplying air therein. The suction line 15 is normally opened, while the discharging line 16 is opened only at a time when supplying air into the suction boxes 13. By closing the discharging line 16 and suctioning air inside the suction boxes 13 through the suction line 15, the pressure inside the suction box is reduced to a reduced pressure or to vacuum, the planographic printing plate P is sucked onto the suction belt 11. On the contrary, the planographic printing plate P is released by supplying air into the suction boxes 13 by opening the discharging line 16 while opening the suction line 15 so as to break the vacuum inside the suction boxes 13.

Note that, in addition to the example shown in FIG. 4, as shown in FIG. 5, the suction conveyer 10 includes an embodiment wherein the suction boxes 13 and discharging boxes 14 are alternately arranged inside the suction belt 11, and the suction line 15 may be connected to the suction boxes 13 and the discharging line 16 is connected to the discharging boxes 14. Further, as shown in FIG. 6, the suction line 15 and the discharging line 16 may be connected to some of the suction boxes 13, for example, the two suction boxes 13 on the upstream side with respect to the charging direction ‘a’ and only the suction line 15 may be connected to the remaining suction boxes 13. Note that, in the above aspects, a predetermined number of discharge holes are formed also to the lower surfaces of the discharging boxes 14, and the inner surface of the suction belt 11 slides on the lower surfaces.

When the planographic printing plate P is sucked, the insides of the suction boxes 13 are made to a pressure-reduced state or to a vacuum state by closing the discharging line 16 and discharging the air in the suction boxes 13 through the suction line 15 in any of the aspects shown in FIGS. 5 and 6. In contrast, the planographic printing plate P is released from the front surface of the suction belt 11 by supplying air to the discharging boxes 14 by opening the discharging line 16 and pressurizing the insides of the discharging boxes 14. Note that when the planographic printing plate P is released in the aspect shown in FIG. 6, the pressure-reduced state or the vacuum state in the discharging boxes 14 is disrupted by supplying air into the discharging boxes 14 as well as supplying air from the discharging line 16 into the two suction boxes 13 on the upstream side with respect to the charging direction ‘a’ at the same time.

The height from the collection surface 2A of the collecting table 2 to the suction conveyer 10 is set preferably in the range of 200 to 250 mm to prevent an planographic printing plate P charged later from interfering with an planographic printing plate P charged previously and fell along the back guide plates 1.

As shown in FIGS. 1 and 7 to 9, the mechanism for causing the edge support plates 9 to appear or disappear from the side guide members 8 has a shaft 20 disposed outside the vertical portions 8A of the side guide members 8 with respect to the collecting table 2, a motor 21 for rotating the shaft 20, and speed reduction gears 23, 22 for transmitting the rotation of the motor 21 to the shaft 20. The edge support plates 9 are fixed to the shaft 20 along the longitudinal direction thereof. When the motor 21 rotates, the shaft 20 is also rotated, thereby the edge support plates 9 also rotate about the axial line of the shaft 20. With this operation, the edge support plates 9 project from the side guide members 8 toward the collecting table 2 as shown by a solid line in FIG. 9 and retracted outside the side guide members 8 as shown by a double-dashed line.

As shown in FIG. 10, each of the back stoppers 4 has a back stopper plate 40 which is in contact with the charged planographic printing plate P and a shock absorber device 43 for absorbing a shock along the charging direction ‘a’ of the back stopper plate 40.

As shown in, for example, Japanese Patent Application Laid-Open (JP-A) No. 8-290860, the shock absorber device 43 has a first shock absorbing mechanism 41 for absorbing shock caused when the planographic printing plate P falling along the charging direction ‘a’ is abutted against the back stopper plates 40 and a second shock absorbing mechanism 42 continuously disposed to the first shock absorbing mechanism 41 for absorbing reaction force caused by the first shock absorbing mechanism 41 returning toward upstream with respect to the charging direction ‘a’.

The first shock absorbing mechanism 41 is composed of a spline shaft 41A to which the back stopper plate 40 is fixed, a moving cylinder 41B positioned outside the spline shaft 41A, a ball holder 41C disposed inside the moving cylinder 41B and holding the spline shaft 41A so that it advances and retracts upstream and downstream with respect to the charging direction ‘a’, and a coil spring 41D interposed between the back stopper plate 40 and the moving cylinder 41B and urging the back stopper plate 40 upstream with respect to the charging direction ‘a’.

In contrast, the second shock absorbing mechanism 42 has a fixed external cylinder 42A, a ball holder 42B holding the moving cylinder 41B inside the fixed external cylinder 42A so that it advances and retracts upstream and downstream with respect to the charging direction ‘a’, and a coil spring 42C urging the moving cylinder 41B upstream with respect to the charging direction ‘a’.

The coil spring 42C has a spring constant larger than that of the coil spring 41D. Accordingly, the inertia received by the back stopper plate 40 is at first absorbed by the coil spring 41D. Then, the reaction force caused by the first shock absorbing mechanism 41 when returning to the original position thereof is absorbed by the coil spring 42C.

Note that the measurement or position of the back stoppers 4 as well as the back guide plate 1 can be changed in accordance with the measurement of the planographic printing plate P to be charged along the charging direction ‘a’ thereof. Specifically, when the planographic printing plate P having a small measurement along the charging direction ‘a’ is charged, the back stoppers 4 and the back guide plates 1 are positioned near to the front stopper 6, whereas when the planographic printing plate P having a large measurement along the charging direction ‘a’ is charged, the back stoppers 4 and the back guide plates 1 are positioned away from the front stopper 6.

[Operation]

An operation of the sheet collecting apparatus 100 will be explained below.

First, the collecting table 2 is moved upward by a lifter (not shown).

When the collecting table 2 is moved upward to a predetermined height, the belt conveyor 200 charges the planographic printing plate P along the charging direction ‘a’. At the time when the planographic printing plate P is charged, air is jetted toward the planographic printing plate P from the auxiliary air nozzle 7 and the planographic printing plate P is lifted toward the suction conveyer 10.

The charged planographic printing plate P is sucked by the suction conveyer 10 and transported along the charging direction ‘a’. When the planographic printing plate P is transported over the collecting table 2, suction of the planographic printing plate P onto the suction conveyer 10 is released by supplying air into the suction boxes 13 to break the reduced pressure or vacuum state therein or by supplying air into the discharging box 14 so that the planographic printing plate is released from the suction belt 11 as shown by P₁ in FIG. 11.

When the planographic printing plate P is released from the suction belt 11, the upstream one side of the planographic printing plate P is guided first by the front stopper 6 with respect to the charging direction ‘a’, and next the two sides of the planographic printing plate P along the charging direction ‘a’ are guided by the side guide members 8 as well as the planographic printing plate P is received by the upper edge of the back guide plates 1 and by the approximate central portions of the back stopper plates 40 in the back stoppers 4 as shown by P2 in FIG. 11.

When the back stopper plate 40 receives and stops the planographic printing plate P, the shock received by the back stopper 40 is absorbed by the shock absorber device 43 as described below.

First, as shown by a solid line in FIG. 11, the back stopper 4 is moved downstream along the charging direction ‘a’ by the shock from the planographic printing plate P. As a result, the coil spring 41D of the first shock absorbing mechanism 41 is contracted. Next, the force of extending the coil spring 41D causes to move the moving cylinder 41B downstream along the charging direction ‘a’. However, since the moving cylinder 41B is urged upstream with respect to the charging direction ‘a’ by the coil spring 42C of the second shock absorbing mechanism 42 and moreover the coil spring 42C has the spring constant larger than that of the coil spring 41D, the moving cylinder 41B is returned to an original position by the urging force of the coil spring 42C. As a result, although the back stopper plate 40 also receives force for causing it to return upstream with respect to the charging direction ‘a’ as shown by a double-dashed line in FIG. 11, the force is absorbed by the coil spring 41D.

Accordingly, although the planographic printing plate P is pushed back toward the front stopper 6 as shown by P₃ in FIG. 11, since force of pushing back the planographic printing plate P is caused by the coil spring 41D having a small spring constant, the planographic printing plate P is not pushed back toward the front stopper 6 by a large amount of force.

As described above, in the sheet collecting apparatus 100 of the exemplary embodiment 1, by disposing the back guide plates 1, the back stoppers 4 can be employed only for absorbing shock. Thus, the spring reaction in the back stoppers 4 is reduced as much as possible by arranging them as described above so that the force for pushing and returning the planographic printing plate P toward the front stopper 6 can be reduced as much as possible.

Then, the final one side, i.e., the downstream side of the planographic printing plate P is guided along the charging direction ‘a’ by the back guide plate 1 as well as the planographic printing plate P is received by the edge support plates 9 from the downstream side thereof as shown by P3 in FIG. 11.

When the planographic printing plate P is received by the edge support plates 9, it is dropped onto the collecting table 2 by pulling the edge support plates 9 to the outsides of the side guide members 8.

When the sheet collecting apparatus 100 is used as described above, not only planographic printing plates P can be collected but also a shock in a height direction, which is generated when a new planographic printing plate is dropped onto the collecting table 2 or onto the sheet collecting surface 51, can be absorbed in a state that a movement in a direction along the charging direction ‘a’ is almost eliminated between the collecting table 2 or the planographic printing plate P, which is already collected onto the collecting table 2 and forms the sheet collecting surface 51, and a newly charged planographic printing plate P. Accordingly, even if an planographic printing plate such as CTP whose printing layer is liable to be damaged can be collected without a slip sheet.

Claims

1. A sheet collecting apparatus for positioning a sheet charged by a charging means at a predetermined position and stacking it in a layer state; the sheet collecting apparatus comprising:

a collecting table on which the sheet charged by the charging means is collected;

a suctioning/transporting means for suctioning and transporting the sheet charged by the charging means along a charging direction and releasing the sheet above the collecting table;

back stoppers for receiving the sheet transported by the suctioning/transporting means downstream of the collecting table along a transport direction of the sheet; and

a back guide disposed downstream of the collecting table along the transport direction of the sheet for regulating a position along the transport direction of the sheet received by the back stoppers.

2. The sheet collecting apparatus of claim 1, comprising a pair of side guide members for regulating a charge path of the sheet transported by the suctioning/transporting means and released from the suctioning/transporting means above the collecting table.

3. The sheet collecting apparatus of claim 2, comprising edge support members disposed so that they can appear or disappear from the side guide members and receiving the sheet from under them by projecting from the side guide members when the sheet is released from the suctioning/transporting means.

4. The sheet collecting apparatus of claim 1, comprising a front stopper disposed opposite to the back stoppers and to a back guide member across the collecting table.

5. The sheet collecting apparatus of claim 2, comprising a front stopper disposed opposite to the back stoppers and to a back guide member across the collecting table.

6. The sheet collecting apparatus of claim 3, comprising a front stopper disposed opposite to the back stoppers and to a back guide member across the collecting table.

7. The sheet collecting apparatus of claim 1, wherein the suctioning/transporting means is a suction conveyer comprising a breathable suction belt rotating in a predetermined direction and suction boxes disposed inside the suction belt for suctioning the sheet onto the front surface of the suction belt by sucking air through the suction belt.

8. The sheet collecting apparatus of claim 2, wherein the suctioning/transporting means is a suction conveyer comprising a breathable suction belt rotating in a predetermined direction and suction boxes disposed inside the suction belt for suctioning the sheet on to the front surface of the suction belt by sucking air through the suction belt.

9. The sheet collecting apparatus of claim 3, wherein the suctioning/transporting means is a suction conveyer comprising a breathable suction belt rotating in a predetermined direction and suction boxes disposed inside the suction belt for suctioning the sheet on the front surface of the suction belt by suctioning air through the suction belt.

10. The sheet collecting apparatus of claim 1, wherein the back guide member is formed to have a sheet receiving height as a height for receiving the sheet set higher than the lower edges of the back stoppers

11. The sheet collecting apparatus of claim 2, wherein the back guide member is formed to have a sheet receiving height as a height for receiving the sheet set higher than the lower edges of the back stoppers.

12. The sheet collecting apparatus of claim 3, wherein the back guide member is formed to have a sheet receiving height as a height for receiving the sheet set higher than the lower edges of the back stoppers.

13. The sheet collecting apparatus of claim 2, wherein a sheet receiving height as a height for receiving the sheet by the back guide member is lower than a positioning height for positioning the sheet by the side guide members and the front stopper.

14. The sheet collecting apparatus of claim 3, wherein a sheet receiving height as a height for receiving the sheet by the back guide member is lower than a positioning height for positioning the sheet by the side guide members and the front stopper.

15. The sheet collecting apparatus of claim 1, comprising an auxiliary air nozzle disposed below the inlet side edge of the suctioning/transporting means from which the sheet is charged for lifting the sheet sucked and transported by the suctioning/transporting means upward by jetting air upward.

16. The sheet collecting apparatus of claim 2, comprising an auxiliary air nozzle disposed below the inlet side edge of the suctioning/transporting means from which the sheet is charged for lifting the sheet sucked and transported by the suctioning/transporting means upward by jetting air upward.

17. The sheet collecting apparatus of claim 3, comprising an auxiliary air nozzle disposed below the inlet side edge of the suctioning/transporting means from which the sheet is charged for lifting the sheet sucked and transported by the suctioning/transporting means upward by jetting air upward.

18. The sheet collecting apparatus of claim 4, wherein the front stopper is formed such that the position thereof can be changed according to the measurement of a sheet to be charged in the charging direction thereof.

19. The sheet collecting apparatus of claim 7, wherein the front stopper is formed such that the position thereof can be changed according to the measurement of a sheet to be charged in the charging direction thereof.

20. The sheet collecting apparatus of claim 10, wherein the front stopper is formed such that the position thereof can be changed according to the measurement of a sheet to be charged in the charging direction thereof.

21. The sheet collecting apparatus of claim 13, wherein the front stopper is formed such that the position thereof can be changed according to the measurement of a sheet to be charged in the charging direction thereof.

22. The sheet collecting apparatus of claim 15, wherein the front stopper is formed such that the position thereof can be changed according to the measurement of a sheet to be charged in the charging direction thereof.

23. A method of collecting a sheet charged by a charging means along a predetermined direction on a collecting table of a sheet collecting apparatus in a layer state, the sheet collecting apparatus comprising the collecting table, a suctioning/transporting means disposed above the collecting table, back stoppers disposed downstream of the collecting table along a transport direction of the sheet, and a back guide disposed downstream of the collecting table along the transport direction of the sheet adjacent to the back stoppers, the method comprising:

suctioning the sheet charged by the charging means by the suctioning/transporting means, transporting the sheet along the charging direction of the sheet, and releasing the sheet above the collecting table;

receiving the sheet released from the suctioning/transporting means downstream of the collecting table along the transport direction of the sheet by the back stoppers; and

regulating a position along the transport direction of the sheet, which is received by the back stoppers, by the back guide member.