Sheet placement device, sheet processing device, and image forming system

Abstract

To provide a sheet placement device which increases a placement amount while reducing damage to a folded sheet.SOLUTION: A sheet placement device places a folded sheet to which folding processing is applied by a sheet folding device. The sheet placement device comprises: a placement part with a placement surface on which the folded sheet is placed; a rotating body for storing the folded sheet discharged from the sheet folding device in an arc-shaped storage groove and rotating to change a direction of the folded sheet to a direction intersecting with the placement surface and be placed on the placement surface; and a guide member provided on an outer wall defining an outer periphery surface of the storage groove and moving between a contact position in contact with the folded sheet stored in the storage groove and a separation position separating from the folded sheet stored in the storage groove.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet stacking device, a sheet processing device, and an image forming system. [Background technology]

[0002] Conventionally, sheet stacking devices have been known that stack multiple folded sheets that have been folded by a sheet folding device on a tray. However, such sheet stacking devices have a problem in that the folded portions of the folded sheets swell and increase in volume, reducing the stacking capacity.

[0003] Therefore, in order to solve the above problem, Patent Document 1 discloses a technology that uses a rotating body that stores folded sheets in a storage groove and rotates, to redirect folded sheets discharged from a sheet folding device so that they intersect with the tray's loading surface and are then loaded onto the tray. Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology of Patent Document 1, the folded sheets may not be able to properly enter the storage grooves or may not be able to move smoothly from the storage grooves to the tray, which may result in damage to the folded sheets.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet stacking device that increases the stacking capacity while reducing damage to folded sheets. [Means for solving the problem]

[0006] In order to solve the above technical problems, one aspect of the present invention is a sheet stacking device that stacks folded sheets that have been folded by a sheet folding device, and is characterized by comprising: a loading section having a loading surface on which the folded sheets are placed; a rotating body that stores the folded sheets discharged from the sheet folding device in an arc-shaped storage groove and rotates to turn the folded sheets so that they are placed on the storage surface in a direction that intersects with the storage surface; and a guide member that is provided on an outer wall that defines the outer peripheral surface of the storage groove and moves between a contact position where it contacts the folded sheets stored in the storage groove and a separation position where it is separated from the folded sheets stored in the storage groove. [Effects of the Invention]

[0007] According to the present invention, it is possible to obtain a sheet stacking device that increases the stacking capacity while reducing damage to folded sheets. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an external view of an image forming system. [Figure 2] FIG. 2 is a diagram illustrating the internal configuration of the sheet folding device. [Figure 3] An example of a folded sheet that has been folded by the sheet folding device. [Figure 4] FIG. 2 is a schematic diagram of a sheet stacking device according to the first embodiment. [Figure 5] FIG. 1 is a hardware configuration diagram of an image forming system according to a first embodiment. [Figure 6] 10 is a flowchart of a discharge control process. [Figure 7] 7A and 7B are diagrams showing the state of the sheet stacking device in steps S12 and S13 in FIG. 6; [Figure 8] 7A to 7C are diagrams showing the states of the sheet stacking device in steps S13 to S15 in FIG. 6; [Figure 9] FIG. 10 is a schematic view of a sheet stacking device according to a second embodiment. [Figure 10] FIG. 10 is a hardware configuration diagram of an image forming system according to a second embodiment. [Figure 11]6A and 6B are diagrams illustrating a state of the sheet stacking device during discharge control processing. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Configuration of image forming system 10] First, an image forming system according to the present invention will be described. Fig. 1 is an external view of an image forming system 10. As shown in Fig. 1, the image forming system 10 is configured by connecting an image forming apparatus 100, a sheet folding apparatus 200, a sheet stacking apparatus 300, and a post-processing apparatus 400. The sheet folding apparatus 200 and the sheet stacking apparatus 300 are examples of sheet processing apparatuses.

[0010] The image forming apparatus 100 forms an image on a sheet and discharges the sheet with the image formed thereon to the sheet folding apparatus 200. The image forming apparatus 100 includes a storage tray for storing sheets, a conveying unit for conveying the sheets stored in the storage tray, and an image forming unit for forming an image on the sheet conveyed by the conveying unit. The image forming unit may be of an inkjet type that forms an image using ink, or of an electrophotographic type that forms an image using toner. The configuration of the image forming apparatus 100 is already well known, so a detailed description thereof will be omitted.

[0011] The housing of the image forming apparatus 100 has an internal space that can be accessed from outside the image forming apparatus 100. The internal space is located, for example, slightly above the center of the housing in the vertical direction. The internal space is exposed to the outside by cutting out an outer wall of the housing. Furthermore, a sheet folding device 200 and a sheet stacking device 300 can be installed in the internal space.

[0012] The sheet folding device 200 performs a folding process on the sheets on which images have been formed by the image forming device 100, folding them into a predetermined shape (for example, a Z-fold, an outward tri-fold, or a double fold), and discharges the sheets to the sheet stacking device 300 or the post-processing device 400. The sheet stacking device 300 is a device that can stack a plurality of sheets (hereinafter referred to as "folded sheets S") that have been folded by the sheet folding device 200. Details of the sheet folding device 200 will be described later with reference to FIG. 2, and details of the sheet stacking device 300 will be described later with reference to FIG. 4. The post-processing device 400 performs predetermined post-processing (for example, alignment, binding, and hole punching) on the folded sheets S discharged from the sheet folding device 200. Note that the post-processing device 400 is optional.

[0013] [Configuration of sheet processing device] Fig. 2 is a diagram illustrating a schematic internal configuration of the sheet folding device 200. Note that the configuration of the sheet folding device 200 illustrated in Fig. 2 is an example, and the configuration is not limited to this, and any configuration that can perform a folding process on a sheet can be employed.

[0014] The sheet folding device 200 includes a plurality of conveying means for performing circulatory conveyance to stack sheets to form a sheet bundle, and a plurality of conveying paths that define a conveying space for the sheets and sheet bundles by the conveying means. Also, a plurality of sheet detection sensors are installed in each conveying path to detect the conveying position of the sheets. Each sheet detection sensor is installed at a predetermined position for controlling the conveyance of the sheets and sheet bundles, which will be described later. Each conveying means is configured by a pair of conveying rollers. That is, the sheet and sheet bundle are conveyed in a predetermined direction by the nip of each conveying roller pair. Furthermore, folding processing is performed on the sheet and sheet bundle depending on how they are fed into the nip of each conveying roller pair. Therefore, the plurality of conveying means also constitute a folding means.

[0015] The sheet folding device 200 has roughly seven conveying paths. As shown in Fig. 2, the sheet folding device 200 has a first conveying path W1, a second conveying path W2, a third conveying path W3, a fourth conveying path W4, a fifth conveying path W5, a sixth conveying path W6, and a seventh conveying path W7.

[0016] A plurality of roller pairs are arranged along each of the first conveying path W1, the second conveying path W2, the third conveying path W3, the fourth conveying path W4, the fifth conveying path W5, the sixth conveying path W6, and the seventh conveying path W7. That is, in the conveying paths for conveying sheets, roller pairs constituting the zeroth conveying means R0, the first conveying means R1, the second conveying means R2, the third conveying means R3, the fourth conveying means R4, the fifth conveying means R5, the sixth conveying means R6, the seventh conveying means R7, and the eighth conveying means R8 are arranged at respective predetermined positions. The start and stop of rotation of each of these conveying roller pairs as conveying means is controlled by a control program executed by a controller 500, which will be described later. This control starts and stops sheet conveyance.

[0017] The sheet folding device 200 also includes a conveyance branching means for switching the sheet conveyance direction. The conveyance branching means enables the sheet folding device 200 to perform multiple conveyance processes on sheets that are carried in from upstream and held within the unit. The conveyance processes described below are processes that are switched in conjunction with the sheet carry-in process.

[0018] More specifically, the first conveying path W1 is connected to an entrance 21 that receives sheets from the image forming apparatus 100. The second conveying path W2 is connected to the first conveying path W1 at a connection point T1. The third conveying path W3 is connected to the end of the second conveying path W2 opposite to the connection point T1. The third conveying path W3 is also connected to the first conveying path W1 at a connection point T2. The connection point T2 is located closer to the entrance 21 than the connection point T1 of the first conveying path W1. In other words, the first conveying path W1, the second conveying path W2, and the third conveying path W3 form a circulating conveying path that overlaps multiple sheets that are conveyed at predetermined time intervals to form a sheet stack.

[0019] The fourth transport path W4 is connected to the first transport path W1 at a connection point T1. In other words, the second transport path W2 and the fourth transport path W4 branch off from the first transport path W1 at the connection point T1. The fifth transport path W5 is connected to the second transport path W2 at a connection point T3. The connection point T3 is closer to the third transport path W3 than the connection point T1 on the second transport path W2. The ends of the fourth transport path W4 and the fifth transport path W5 opposite the connection points T1 and T3 are connected at a connection point T4. In other words, the fourth transport path W4 and the fifth transport path W5 merge at the connection point T4.

[0020] The sixth transport path W6 and the seventh transport path W7 are connected to the fourth transport path W4 and the fifth transport path W5 at a connection point T4. The sixth transport path W6 and the seventh transport path W7 extend in different directions from the connection point T4. That is, the sixth transport path W6 and the seventh transport path W7 branch off at the connection point T4.

[0021] The conveying direction in the first conveying path W1 is the direction from the entrance 21 toward the connection point T1. The conveying direction in the second conveying path W2 is the direction from the connection point T1 via the connection point T3 toward the third conveying path W3. The conveying direction in the third conveying path W3 is the direction from the second conveying path W2 toward the connection point T2. The conveying direction in the fourth conveying path W4 is the direction from the connection point T1 toward the connection point T4. The conveying direction in the fifth conveying path W5 is the direction from the connection point T3 toward the connection point T4. The conveying direction in the sixth conveying path W6 is the direction from the connection point T4 toward the seventh conveying means R7. The conveying direction in the seventh conveying path W7 is the direction from the connection point T4 toward the exit 22 of the sheet folding device 200.

[0022] The zeroth conveying means R0 is disposed between the entrance 21 and the connection point T2. The first conveying means R1 is disposed on the first conveying path W1 between the connection points T2 and T1. The second conveying means R2 is disposed between the second conveying path W2 and the third conveying path W3. The third conveying means R3 is disposed on the third conveying path W3 on the connection point T2 side of the second conveying path W2. The fourth conveying means R4 is disposed on the fourth conveying path W4 between the connection points T1 and T4. The fifth conveying means R5 is disposed on the fifth conveying path W5 between the connection points T3 and T4. The sixth conveying means R6 is disposed at the connection point T4. The seventh conveying means R7 is disposed on the sixth conveying path W6 downstream of the connection point T4 in the conveying direction. The eighth conveying means R8 is disposed on the seventh conveying path W7 between the connection point T4 and the exit 22.

[0023] The sheet folding device 200 has control functions for executing "discharge conveyance," "circulation conveyance," and "fold conveyance." "Discharge conveyance," "circulation conveyance," and "fold conveyance" are each conveyance processes for sheets and the like executed in the sheet folding device 200, and are all executed by the operation of each conveyance roller pair and the operation of the conveyance branching means. That is, the control operation related to "discharge conveyance," the control operation related to "circulation conveyance," and the control operation related to "fold conveyance" are all executed by the control of the controller 500. Furthermore, the execution of each control may be switched based on a control command from the controller 500.

[0024] The discharge conveyance is a conveyance process in which a sheet bundle formed by overlapping a new sheet with a previously conveyed sheet is conveyed downstream in the conveyance direction and discharged. Specifically, "discharge conveyance" refers to conveying a sheet or sheet bundle in the same direction as the conveyance direction by the first conveyance unit R1. Specifically, discharge conveyance refers to conveying a sheet or sheet bundle from the first conveyance path W1 to the fourth conveyance path W4 downstream in the conveyance direction, or conveying a sheet or sheet bundle from the first conveyance path W1 to the fifth conveyance path W5 via the second conveyance path W2. In other words, when discharge conveyance is performed, the sheet or sheet bundle is conveyed from the first conveyance path W1 toward the exit 22 of the sheet folding device 200 regardless of whether the sheet or sheet bundle has been folded or has been folded.

[0025] The circulating conveyance is a conveyance process in which a sheet or a sheet stack is circulated and conveyed upstream of the first conveyance means R1 (first conveyance path W1) without changing the leading edge of the sheet in the conveyance direction when conveyed along the first conveyance path W1, i.e., without changing the leading edge of the sheet in the conveyance direction by the first conveyance means R1. In other words, the circulating conveyance refers to conveying a sheet or a sheet stack from the first conveyance path W1 to the second conveyance path W2 downstream in the conveyance direction. Note that in the "circulating conveyance," in order to return a sheet sent to the second conveyance path W2 upstream of the first conveyance path W1, the sheet is conveyed from the second conveyance path W2 to the third conveyance path W3 and then circulated from the third conveyance path W3 to the first conveyance path W1. The conveyance path that circulates the sheet is referred to as the "circulating conveyance path." The circulating conveyance is performed when the number of sheets constituting the sheet stack has not reached a predetermined number. The circulating conveyance is also performed until the number of sheets constituting the sheet stack reaches the upper limit number for the overlap folding process and the control command notifying the start of overlap folding is recognized by the controller 500.

[0026] The "folding conveyance" is a conveyance process in which a predetermined folding position of a sheet or sheet bundle is fed into the nip of the first folding device F1. In other words, the "folding conveyance" corresponds to conveyance in which the leading edge of the sheet or sheet bundle in the conveying direction by the first conveying device R1 is changed and the sheet or sheet bundle is fed from the first conveying path W1 to the second conveying path W2 downstream in the conveying direction. Therefore, in the folding conveyance, the portion of the sheet or sheet bundle that is not the leading edge in the conveying direction when passing through the nip of the first conveying device R1 is fed into the second conveying path W2 as the leading edge in the conveying direction, and the leading edge after the change in the conveying direction passes through the nip of the first folding device F1, forming a fold. In other words, the leading edge in the changed conveying direction (the leading edge in the conveying direction when fed into the second conveying path W2) becomes the fold. When forming a second fold, a portion different from the leading edge in the conveying direction is set as the new leading edge in the conveying direction and fed into another conveying path. In this embodiment, the second fold is formed by feeding the sheet or sheet bundle into the fifth conveying path W5. As described above, "folding and conveying" refers to conveying a sheet or a sheet stack to form a fold.

[0027] The conveyance branching means may also switch the conveyance from the first conveyance path W1 to the fifth conveyance path W5 via the second conveyance path W2 and the third conveyance path W3. The conveyance control in this case is also included in the "folding conveyance." As described above, the sheet folding device 200 is provided with multiple conveyance paths so as to be able to switch between conveyance that changes the leading edge of the sheet or sheet stack in the conveyance direction and conveyance that does not change the leading edge in the conveyance direction. The sheet folding device 200 is also provided with multiple conveyance branching means so as to switch between these conveyance paths.

[0028] [Description of transport branching means] The multiple conveying / diverging means are configured by a combination of a first conveying means R1, a fourth conveying means R4, a first folding means F1, a fifth conveying means R5, etc. For example, as shown in FIG. 5, the multiple conveying / diverging means are configured as a first conveying / diverging means J1, a second conveying / diverging means J2, and a third conveying / diverging means J3. These multiple conveying / diverging means are included in various loads 220 whose operation is controlled by a controller 500. Therefore, the controller 500 controls the operation of the multiple conveying / diverging means to control the operation of the conveying means that conveys sheets and sheet stacks, and controls selective switching between multiple conveying paths. Note that a first folding means F1 and a second folding means F2 for folding sheets and sheet stacks are also arranged along the circulating conveying path.

[0029] As will be described later, before the sheet conveyed from the image forming device 100 is discharged from the downstream exit 22 (see Figure 2), the sheet folding device 200 accepts the next sheet and performs a circular conveyance as a conveyance process in which the previous sheet and the subsequent sheet are overlapped, and a folding conveyance as a conveyance process for performing a predetermined folding process on the sheet and sheet stack.

[0030] In the following description, the sheet (preceding sheet) that is first transported from the image forming apparatus 100 to the sheet folding apparatus 200 will be referred to as "preceding sheet 1." Furthermore, the sheet that is transported following the preceding sheet 1 and that is to be superimposed on the preceding sheet 1 will be referred to as "subsequent sheet 2." Furthermore, the sheet that is transported following the subsequence sheet 2 and that is to be subjected to the superimposition process together with the preceding sheet 1 and the subsequence sheet 2 will be referred to as "next sheet 3." Furthermore, the multiple sheets that are superimposed and bundled together will be referred to as a "sheet stack," as has already been used in the description.

[0031] There is a predetermined upper limit to the number of sheets when performing overlapping or folding processing in the sheet folding device 200. This upper limit is referred to as the "maximum number of sheets." In the following description, an example in which the maximum number of sheets is three is illustrated, but the maximum number of sheets in the sheet folding device 200 according to this embodiment is not limited to three, and the maximum number of sheets can also be two or more.

[0032] [Explanation of each transportation method] In the sheet folding device 200, a zeroth conveying means R0 serving as an inlet conveying roller pair is disposed near the inlet 21 that receives sheets from the image forming apparatus 100. When the controller 500 receives information from the image forming apparatus 100 informing it that the preceding sheet 1 has been discharged, the drive motor that rotates the zeroth conveying means R0 starts to rotate. After that, when the leading edge of the preceding sheet 1 reaches the nip of the roller pair of the zeroth conveying means R0, the zeroth conveying means R0 conveys the preceding sheet 1 downstream.

[0033] The first conveying means R1 is arranged along the first conveying path W1 provided downstream of the zeroth conveying means R0, and is composed of a pair of rollers having a nip that holds the conveyed preceding sheet 1, and conveys the preceding sheet 1 downstream.

[0034] The first conveying means R1 also functions as a skew correction means that corrects the tilt of the posture of the preceding sheet 1 in the conveying direction by bringing the leading edge of the preceding sheet 1 conveyed from upstream into contact with the nip. The first conveying means R1 performs skew correction to correct any irregularities in the conveying posture of the sheet (preceding sheet 1) conveyed from the zeroth conveying means R0 to the first conveying means R1. When performing this skew correction, the rotation of the pair of conveying rollers that is performed as part of the conveying operation is temporarily stopped, or the pair of conveying rollers is controlled to rotate in the reverse direction, which is the opposite operation to the normal conveying operation. If the pair of conveying rollers that constitute the first conveying means R1 are rotated in the reverse direction when performing skew correction, the reverse rotation of the pair of conveying rollers is stopped when the preceding sheet 1 contacts the nip. Thereafter, the pair of conveying rollers starts rotating (forward) at a predetermined timing to convey the preceding sheet 1 downstream.

[0035] The first folding device F1 is disposed on the second conveying path W2 between the connection points T1 and T3. The first folding device F1 is a pair of rollers disposed opposite to each other on the second conveying path W2 and forming a nip. The preceding sheet 1 is guided from the first conveying path W1 to the second conveying path W2 through a conveying path guided by this nip. Conveyance control in which the preceding sheet 1 passes through the first folding device F1 without changing its leading edge in the conveying direction of the first conveying device R1 corresponds to "circular conveyance." Conveyance control in which the leading edge of the preceding sheet 1 in the conveying direction when guided by the nip of the first folding device F1 and passing through the conveying path is in a different position from the leading edge of the preceding sheet 1 in the conveying direction of the first conveying device R1 corresponds to "fold conveyance." The sheet folding device 200 switches between whether the leading edge of the preceding sheet 1 in the conveying direction when passing through the first folding device F1 is the same as when passing through the nip of the first conveying device R1 or a different position by operating multiple conveying roller pairs.

[0036] Furthermore, the third conveying means R3 guides the preceding sheet 1 guided to the second conveying path W2 to the third conveying path W3 for circular conveyance, and temporarily stops the conveyance of the preceding sheet 1 on the third conveying path W3. The preceding sheet 1 temporarily stopped on the third conveying path W3 resumes conveyance when the succeeding sheet 2 is received from the image forming apparatus 100. This allows the preceding sheet 1 to return to the upstream side of the first conveying means R1 on the first conveying path W1, and to merge with the succeeding sheet 2 at a predetermined position on the first conveying path W1 so that they can be superimposed on each other. The circular conveying path is configured as described above.

[0037] In the circulating conveyance path described above, a sheet bundle is formed by overlapping the preceding sheet 1 and the succeeding sheet 2. Next, a flow of a folding process (overlapping folding process) for the sheet bundle will be described with reference to FIG.

[0038] The folding process for the sheet bundle is mainly performed by the first folding means F1, which operates under control after the controller 500 receives an "overlap folding process start instruction" from the controller 500. Then, the sheet bundle that has been folded (overlap folding process) by the first folding means F1 is transferred from the second conveying path W2 to the fifth conveying path W5 and discharged. The fourth conveying means R4, the fifth conveying means R5, and the first folding means F1 are driven by the same drive motor. The drive motor can rotate in both the forward and reverse directions. By switching the rotation direction of the drive motor, it is possible to switch between circulating and folding the sheet bundle, in which the preceding sheet 1 and the succeeding sheet 2 are overlapped.

[0039] Furthermore, a branching member 23 is disposed upstream of the sixth conveying means R6 in the conveying direction. The branching member 23 appropriately switches between guiding the sheets (sheet stack) to the sixth conveying path W6 side and guiding the sheets (sheet stack) to the seventh conveying path W7 side. The switching of the conveying direction is achieved by switching the position of the branching member 23. The position of the branching member 23 can be switched by, for example, a solenoid. Note that a drive mechanism including a motor, gears, cams, etc. can also be used instead of a solenoid.

[0040] The sixth conveying path W6 is a path for transferring the folded sheet S to the sheet stacking device 300. The seventh conveying path W7 is a path for transferring the folded sheet S to the post-processing device 400 when the post-processing device 400 is provided downstream of the sheet folding device 200 in the image forming system 10. The post-processing device 400 performs post-processing such as alignment, binding, and hole punching on the folded sheet S.

[0041] A first sheet detection sensor SN1 is disposed downstream of the zeroth conveying means R0 in the first conveying path W1. A second sheet detection sensor SN2 is disposed upstream of the first conveying means R1 in the first conveying path W1. The second sheet detection sensor SN2 is disposed downstream of the first sheet detection sensor SN1 in the first conveying path W1.

[0042] In the third conveying path W3 constituting the circulating conveying path, a third sheet detection sensor SN3 is arranged downstream of the second conveying means R2 (downstream in the conveying direction during circulating conveying). Also, in the third conveying path W3, a fourth sheet detection sensor SN4 is arranged downstream of the third conveying means R3 (downstream in the conveying direction during circulating conveying).

[0043] In the fourth conveying path W4, which constitutes the sheet conveying path during discharge conveyance, a fifth sheet detection sensor SN5 is arranged downstream of the fourth conveying means R4 (downstream in the conveying direction during discharge conveyance). In the fifth conveying path W5, a sixth sheet detection sensor SN6 is arranged downstream of the fifth conveying means R5 (downstream in the conveying direction during discharge conveyance). In the sixth conveying path W6, a seventh sheet detection sensor SN7 is arranged downstream of the sixth conveying means R6 (downstream in the conveying direction during discharge conveyance). In the seventh conveying path W7, an eighth sheet detection sensor SN8 is arranged downstream of the eighth conveying means R8 (downstream in the conveying direction during discharge conveyance).

[0044] [Example of folded sheet S] FIG. 3 shows an example of a folded sheet S that has been folded by the sheet folding device 200. FIGS. 3A and 3B show an example of a folded sheet S that has been folded in half at a single folding position C in the center of the sheet in the conveyance direction. Hereinafter, of both ends of the folded sheet S in the conveyance direction, the end on the folding position C side will be referred to as the "folded end," and the end on the opposite side (the side where the pair of sheet ends are overlapped) will be referred to as the "overlapped end." However, the shape of the folded sheet S that can be formed by the sheet folding device 200 is not limited to the double fold shown in FIG. 3, and various well-known shapes such as an inner tri-fold, an outer tri-fold, and a Z-fold can be realized.

[0045] As an example, when the folding position C of a sheet that has entered the fourth conveying path W4 through the first conveying path W1 reaches the connection point T1, the sheet is nipped by the first folding means F1 with the folding position C at the leading edge. As a result, the sheet is folded in half at the folding position C. Then, the folded sheet S is discharged to the sheet stacking device 300 with the folded end at the leading edge through the second conveying path W2, the third conveying path W3, the first conveying path W1, the fourth conveying path W4, and the sixth conveying path W6. As a result, the folded sheet S in the state shown in FIG. 3A is supplied to the sheet stacking device 300.

[0046] As another example, when the folding position C of a sheet that has entered the fourth conveying path W4 through the first conveying path W1 reaches the connection point T1, the sheet is nipped by the first folding device F1 with the folding position C at the leading edge. This causes the sheet to be folded in half at the folding position C. The sheet is then made to enter the second conveying path W2 and the third conveying path W3 with the folding position C at the leading edge. Furthermore, when the trailing end (overlapping end) of the folded sheet S passes the first folding device F1, the folded sheet S is discharged to the sheet stacking device 300 through the fifth conveying path W5 and the sixth conveying path W6 with the overlapping end at the leading edge. This causes the folded sheet S in the state shown in FIG. 3B to be supplied to the sheet stacking device 300.

[0047] [Configuration of the sheet stacking device 300 according to the first embodiment] 4 is a schematic diagram of a sheet stacking device 300 according to the first embodiment. As shown in FIG. 4, the sheet stacking device 300 mainly includes a tray 310 (mounting section), a rotating body 320, and a guide member 330. The seventh conveying means R7 (conveying section) and the seventh sheet detection sensor SN7 (sheet sensor) may be components of the sheet stacking device 300 instead of being components of the sheet folding device 200. Hereinafter, the direction from the seventh conveying means R7 to the tray 310 via the rotating body 320 will be referred to as the "conveying direction."

[0048] The tray 310 is a plate-like member having a placement surface 311 on which a folded sheet S is placed. The tray 310 is disposed downstream of the seventh conveying means R7 and the rotating body 320 in the conveying direction. The placement surface 311 is inclined upward toward the receiving side in the conveying direction. As shown in FIGS. 8(B) and 8(C), a folded sheet S is placed on the placement surface 311, the folded sheet S being turned so as to intersect with the extending direction of the placement surface 311. The tray 310 includes, for example, a partition 312 (support member), a drive pulley 313, a driven pulley 314, an endless circular belt 315, a slide motor 316, a locking protrusion 317, and a pressure sensor 318.

[0049] The partition 312 protrudes upward from the placement surface 311. The partition 312 supports the folded sheets S placed on the placement surface 311. The partition 312 is supported so as to be slidable along the placement surface 311 in the conveyance direction (the stacking direction of the multiple folded sheets S). The drive pulley 313 and the driven pulley 314 are housed in the tray 310 at positions spaced apart in the conveyance direction. The endless circular belt 315 is stretched around the drive pulley 313 and the driven pulley 314. The slide motor 316 generates a driving force that rotates the drive pulley 313. When the rotational driving force of the slide motor 316 is transmitted to the drive pulley 313, the endless circular belt 315 rotates around the drive pulley 313 and the driven pulley 314. As a result, the partition 312 fixed to the endless circular belt 315 slides along the placement surface 311.

[0050] The locking protrusion 317 protrudes upward from the upstream end of the placement surface 311 in the conveyance direction (i.e., the end closer to the rotating body 320). As shown in FIGS. 8B and 8C, the locking protrusion 317 locks the folded sheets S placed on the placement surface 311 (i.e., prevents the folded sheets S from falling off from the placement surface 311 toward the rotating body 320). Therefore, if the distance between the partitions 312 and the locking protrusion 317 is narrow compared to the number of folded sheets S placed on the placement surface 311, the pressure applied by the folded sheets S to the partitions 312 will be high. Therefore, the pressure sensor 318 detects the pressure applied by the folded sheets S placed on the placement surface 311 to the partitions 312, and outputs a pressure signal indicating the detected pressure to the controller 500.

[0051] The rotating body 320 is disposed downstream of the seventh conveying means R7 in the conveying direction and upstream of the tray 310 in the conveying direction. The rotating body 320 has a cylindrical shape extending in the width direction of the folded sheet S (a direction perpendicular to the conveying direction and thickness direction of the folded sheet S). The rotating body 320 rotates (spins) around a central axis X extending in the width direction of the folded sheet S by the driving force of a rotation motor 324. The rotating body 320 according to this embodiment rotates counterclockwise in FIG. 4.

[0052] A storage groove 321 is formed in the rotor 320. The storage groove 321 extends from the outer circumferential surface of the rotor 320 toward the interior of the rotor 320. In other words, the storage groove 321 formed inside the rotor 320 opens to the outer circumferential surface of the rotor 320. When viewed from the direction in which the central axis x extends, the storage groove 321 is formed in an arc shape surrounding the central axis x. The inner circumferential surface of the storage groove 321 is defined by an inner wall 322 that is continuous with the outer circumferential surface of the rotor 320, and the outer circumferential surface is defined by an outer wall 323 that faces the inner wall 322 in the radial direction of the rotor 320. Meanwhile, the storage groove 321 extends in the direction in which the central axis x extends (i.e., the width direction of the folded sheet S). In the rotor 320 according to this embodiment, the storage grooves 321 are formed at two locations spaced apart in the circumferential direction. However, the number of receiving grooves 321 is not limited to two, and may be one, or three or more.

[0053] As shown in FIG. 7(B), when the opening of storage groove 321 faces sixth conveying path W6, folded sheet S conveyed in the conveying direction by seventh conveying means R7 enters storage groove 321. Storage groove 321, which accommodates folded sheet S, rotates counterclockwise in FIGS. 7 and 8. Furthermore, as shown in FIGS. 8(A) and 8(B), when the opening of storage groove 321 faces tray 310, folded sheet S accommodated in storage groove 321 leaves storage groove 321 and moves to tray 310. At this time, folded sheet S is deflected to a direction intersecting with placement surface 311. That is, by accommodating folded sheet S discharged from sheet folding device 200 in storage groove 321 and rotating, rotating body 320 deflects folded sheet S to a direction intersecting with placement surface 311 and places it on placement surface 311.

[0054] The guide member 330 is provided on the outer wall 323 at the position of the opening of the storage groove 321. Note that the guide member 330 may be provided in all of the storage grooves 321, but in FIGS. 4, 7, and 8, only one guide member 330 is shown. The guide member 330 is supported by the outer wall 323 and is configured to be rotatable about a rotation shaft 331 that extends in the width direction of the folded sheet S. The guide member 330 rotates about the rotation shaft 331 between a contact position shown in FIG. 4(A) and a separated position shown in FIG. 4(B) by the extension and contraction of an air cylinder 332. Note that the drive source that rotates the guide member 330 is not limited to the air cylinder 332.

[0055] The contact position is the position of the guide member 330 that contacts the folded sheet S stored in the storage groove 321. In other words, the contact position is the position where the tip of the guide member 330 is closer to the inner wall 322 of the storage groove 321 than when in the separated position. In other words, the contact position is the position of the guide member 330 that contacts the folded sheet S that is about to enter the storage groove 321 along the sixth conveying path W6 when the opening of the storage groove 321 faces the sixth conveying path W6.

[0056] The separated position is a position of the guide member 330 that is separated from the folded sheet S stored in the storage groove 321. In other words, the separated position is a position where the tip of the guide member 330 is farther from the inner wall 322 of the storage groove 321 than when it is in the contact position. In other words, the separated position is a position of the guide member 330 that is separated from (not in contact with) the folded sheet S that is about to enter the storage groove 321 along the sixth conveying path W6 when the opening of the storage groove 321 faces the sixth conveying path W6.

[0057] Note that, referring to Figure 8(A) or Figure 8(C), the guide members 330 are shown as interfering with the tray 310, but for example, the guide members 330 may be arranged in a comb shape at predetermined intervals in the width direction of the folded sheet S, and the tray 310 may have slits formed therein to allow the guide members 330 to pass through.

[0058] [Control Block of Image Forming System 10] Fig. 5 is a hardware configuration diagram of the image forming system 10 according to the first embodiment. As shown in Fig. 5, the image forming system 10 includes a CPU (Central Processing Unit) 501, a RAM (Random Access Memory) 502, a ROM (Read Only Memory) 503, a HDD (Hard Disk Drive) 504, and an I / F 505, all of which are connected via a common bus 509.

[0059] The CPU 501 is a computing means and controls the overall operation of the image forming system 10. The RAM 502 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 501 processes information. The ROM 503 is a read-only nonvolatile storage medium in which programs such as firmware are stored. The HDD 504 is a nonvolatile storage medium with a large storage capacity that is capable of reading and writing information, and stores an OS (Operating System), various control programs, application programs, etc.

[0060] The image forming system 10 processes a control program stored in the ROM 503, an information processing program (application program) loaded into the RAM 502 from a storage medium such as the HDD 504, and the like using the arithmetic functions of the CPU 501. This processing constitutes a software control unit including various functional modules of the image forming system 10. The combination of the software control unit thus constituted and the hardware resources installed in the image forming system 10 constitutes a functional block that realizes the functions of the image forming system 10. In other words, the CPU 501, RAM 502, ROM 503, and HDD 504 constitute a controller 500 (control unit) that controls the operation of the image forming system 10.

[0061] The I / F 505 is an interface that connects the image forming apparatus 100, the sheet folding apparatus 200, the sheet stacking apparatus 300, and the post-processing apparatus 400 to a common bus 509. The controller 500 operates the image forming apparatus 100, the sheet folding apparatus 200, the sheet stacking apparatus 300, and the post-processing apparatus 400 through the I / F 505. The controller 500 also grasps the position of the folded sheet S using the seventh sheet detection sensor SN7, grasps the pressure applied to the partition 312 using the pressure sensor 318, and grasps the rotation angle (phase) of the rotating body 320 using the rotary encoder of the rotation motor 324.

[0062] Note that Figure 5 illustrates a controller 500 that commonly controls the image forming device 100, the sheet folding device 200, the sheet stacking device 300, and the post-processing device 400, but the controllers installed in each of the devices 100, 200, 300, and 400 may also operate in conjunction with each other.

[0063] [Emission control treatment] Fig. 6 is a flowchart of the discharge control process. Fig. 7 is a diagram showing the state of the sheet stacking device 300 in steps S12-S13 in Fig. 6. Fig. 8 is a diagram showing the state of the sheet stacking device 300 in steps S13-S15 in Fig. 6. The discharge control process is a process for stacking the folded sheets S discharged from the sheet folding device 200 onto the sheet stacking device 300.

[0064] 6 in response to, for example, an image formation instruction being input to image forming system 10. The image formation instruction is an instruction to form an image on a sheet, fold the image-formed sheet, and load it on tray 310. The image formation instruction also includes the number of folded sheets S to be loaded on tray 310. It is assumed that, at the start of the discharge control process, no folded sheets are placed on tray 310, a gap large enough to accommodate one folded sheet S is formed between partition 312 and locking protrusion 317, no folded sheet S is stored in storage groove 321, and guide member 330 is positioned in the separated position.

[0065] First, the controller 500 drives the rotation motor 324 to start the rotation of the rotating body 320 (S11). For example, as shown in FIG. 7A, the controller 500 may start the rotation of the rotating body 320 at a timing when the folded sheet S detected by the seventh sheet detection sensor SN7 can enter the storage groove 321. The controller 500 also continues to rotate the rotating body 320 until the discharge control process is completed. That is, the conveyance of the folded sheet S by the seventh conveying means R7 and the rotation of the rotating body 320 are performed in synchronization.

[0066] Next, in response to the leading edge (the downstream end in the conveying direction) of the folded sheet S reaching the first switching position (S12: Yes), the controller 500 drives the air cylinder 332 to rotate the guide member 330 from the separated position to the contact position (S13). The first switching position is, for example, the position where the guide member 330 at the contact position intersects with the sixth conveying path W6. In other words, the first switching position is a position where the folded sheet S conveyed by the seventh conveying means R7 can come into contact with the guide member 330 at the contact position. As a result, as shown in FIG. 7B, the guide member 330 comes into contact with the folded sheet S entering the storage groove 321, guiding the folded sheet S into the storage groove 321.

[0067] Then, as shown in FIG. 7(C), the rotating body 320, with the folded sheets S accommodated in the accommodating groove 321, continues to rotate. Next, in response to the fact that the accommodating groove 321 accommodating the folded sheets S has reached the second switching position (S14: Yes), the controller 500 drives the air cylinder 332 to rotate the guide member 330 from the contact position to the separation position (S15). The second switching position is, for example, a position where the opening of the accommodating groove 321 accommodating the folded sheets S faces the tray 310. More specifically, the second switching position is, for example, a position where the folded sheets S accommodated in the accommodating groove 321 can move to the tray 310. More specifically, the second switching position is, for example, a position where the folded sheets S contact both the inner circumferential surface of the accommodating groove 321 and the partition 312 (or the folded sheets S already stacked on the tray 310), as shown in FIG. 8(A) or 8(C).

[0068] Then, as the rotating body 320 continues to rotate from the state shown in Figure 8(A), the folded sheet S stored in the storage groove 321 moves between the partition 312 of the tray 310 and the locking protrusion 317, as shown in Figure 8(B).

[0069] Next, the controller 500 determines whether the number of folded sheets S indicated in the image formation instruction has been stacked on the tray 310 (S16). If the controller 500 determines that all folded sheets S have not been stacked (S16: No), the controller 500 determines whether the pressure detected by the pressure sensor 318 is within an allowable range (S17).

[0070] Next, if the controller 500 determines that the pressure detected by the pressure sensor 318 is outside the allowable range (S17: No), it drives the slide motor 316 to slide the partition 312 so that the pressure falls within the allowable range (S18). More specifically, if the pressure exceeds the upper limit of the allowable range, the controller 500 slides the partition 312 away from the locking protrusion 317. If the pressure is below the lower limit of the allowable range (for example, if the folded sheets S stacked on the tray 310 are removed by the user), the controller 500 slides the partition 312 toward the locking protrusion 317. On the other hand, if the controller 500 determines that the pressure detected by the pressure sensor 318 is within the allowable range (S17: Yes), it skips the processing of step S18.

[0071] Next, the controller 500 executes the processes from step S12 onwards again. That is, the controller 500 repeatedly executes the processes of steps S12 to S18 until the number of folded sheets S indicated in the image formation instruction has been stacked on the tray 310 (S16: No). Then, when the controller 500 determines that all of the folded sheets S have been stacked on the tray 310 (S16: Yes), it stops the rotation motor 324 (i.e., the rotating body 320) (S19) and ends the discharge control process.

[0072] [Effects of the first embodiment] According to the first embodiment, the folded sheets S are turned around and stacked on the tray 310 using the rotating body 320, which increases the stacking capacity compared to when the folded sheets S are stacked parallel to the loading surface 311. Furthermore, by providing a guide member 330 at the position of the opening of the storage groove 321, it is possible to guide the folded sheets S entering and leaving the storage groove 321.

[0073] More specifically, this prevents problems such as a part of the folded sheet S being unable to enter the storage groove 321 and the crease widening, or the folded sheet S coming into contact with the partition 312 in this state not being properly stacked on the tray 310. As a result, damage to the folded sheet S is reduced. This is an especially advantageous effect for folded sheets S that are folded so that the end on the downstream side in the conveyance direction widens, as shown in FIG. 3(B).

[0074] Furthermore, according to the first embodiment, the guide member 330 is in a contact position when the folded sheet S enters the storage groove 321, and is in a separated position when the folded sheet S moves from the storage groove 321 to the tray 310, thereby enabling the folded sheet S to smoothly enter and exit the storage groove 321.

[0075] Furthermore, according to the first embodiment, the partition 312 is slid so that the pressure exerted on the partition 312 by the folded sheets S placed on the tray 310 falls within an allowable range, thereby reducing damage to the folded sheets S and allowing the folded sheets S to be stacked appropriately on the tray 310.

[0076] Furthermore, according to the first embodiment, by providing the locking projection 317 on the end of the tray 310 that is closer to the rotating body 320, it is possible to prevent the folded sheets S placed on the tray 310 from being caught in the rotating body 320. This reduces damage to the folded sheets S and prevents interruption of processing due to the occurrence of a jam.

[0077] [Second embodiment] FIG. 9 is a schematic diagram of a sheet stacking device 300A according to the second embodiment. FIG. 10 is a hardware configuration diagram of an image forming system 10A according to the second embodiment. FIG. 11 is a diagram showing the state of the sheet stacking device 300A during discharge control processing. Note that detailed description of commonalities with the first embodiment will be omitted, and differences will be mainly described. The sheet stacking device 300A according to the second embodiment differs from the first embodiment in that it is provided with a guide member 330 in that it is provided with a guide member 340.

[0078] The guide member 340 according to the second embodiment is configured to be slidable along the outer peripheral surface of the storage groove 321 (i.e., the inner peripheral surface of the outer wall 323). The guide member 340 corresponds to, for example, the "arc" portion of a fan-shaped member that rotates about the central axis X. The guide member 340 extends in the width direction of the folded sheet S. The driving force of a guide motor 341 (an example of a driving source) is transmitted to the guide member 340, causing it to slide between a contact position shown in FIG. 9(A) and a separated position shown in FIG. 9(B).

[0079] The contact position is the position of the guide member 340 that contacts the folded sheet S stored in the storage groove 321. In other words, the contact position is the position of the guide member 340 that protrudes from the tip of the outer wall 323 and increases the groove depth of the storage groove 321 (the length over which the inner wall 322 faces the outer wall 323 and the guide member 340). In other words, the guide member 340 at the contact position defines a part of the outer peripheral surface of the storage groove 321. In other words, the contact position is the position of the guide member 340 that contacts the folded sheet S that is about to enter the storage groove 321 along the sixth conveying path W6 when the opening of the storage groove 321 faces the sixth conveying path W6.

[0080] The separated position is a position of the guide member 340 that is separated from the folded sheet S stored in the storage groove 321. In other words, the separated position is a position of the guide member 340 that is retracted into the storage groove 321 to reduce the depth of the storage groove 321. The separated position is a position where the tip of the guide member 330 is farther from the inner wall 322 of the storage groove 321 than when in the contact position. In other words, the separated position is a position of the guide member 330 that is separated from (not in contact with) the folded sheet S that is entering the storage groove 321 along the sixth conveying path W6 when the opening of the storage groove 321 faces the sixth conveying path W6.

[0081] The basic processing content of the discharge control processing according to the second embodiment is the same as that of the first embodiment. That is, as shown in Fig. 11(A), at the start of the discharge control processing, the guide member 340 is disposed in the separated position. Then, in step S13, the controller 500 drives the guide motor 341 to slide the guide member 340 from the separated position to the contact position. Then, in step S15, the controller 500 drives the guide motor 341 to slide the guide member 340 from the contact position to the separated position.

[0082] In the second embodiment, the same effects as in the first embodiment can be obtained.

[0083] [Aspects of the present invention] The contents of the present invention are as follows, for example. <1> In a sheet stacking device for stacking folded sheets that have been folded by a sheet folding device, a loading section having a loading surface on which the folded sheet is placed; a rotating body that stores the folded sheet discharged from the sheet folding device in an arc-shaped storage groove and rotates to turn the folded sheet to a direction intersecting the placement surface and place the folded sheet on the placement surface; This sheet stacking device is characterized by having a guide member provided on an outer wall that defines the outer peripheral surface of the storage groove, and which moves between a contact position where it contacts the folded sheets stored in the storage groove and a separation position where it is separated from the folded sheets stored in the storage groove. <2> The guide member is supported by the outer wall and rotates about a rotation axis extending in the width direction of the folded sheet between the contact position where the tip thereof approaches the inner circumferential surface of the storage groove and the separated position where the tip thereof moves away from the inner circumferential surface of the storage groove. <1> 2 is a sheet stacking device according to the first embodiment. <3> a controller for controlling the position of the guide member in accordance with the position of the folded sheet and the rotation angle of the rotating body; The controller When a leading edge of the folded sheet discharged from the sheet folding device passes a position where the leading edge can contact the guide member at the contact position, the guide member is rotated to the contact position, The above-mentioned method is characterized in that the guide member is rotated to the separated position when the opening of the accommodation groove that accommodates the folded sheets faces the placement section. <2> 2 is a sheet stacking device according to the first embodiment. <4> The guide member slides between the contact position where it projects from the tip of the outer wall to increase the groove depth of the accommodating groove and the separated position where it retracts into the accommodating groove to decrease the groove depth of the accommodating groove. <1> 2 is a sheet stacking device according to the first embodiment. <5> The above-mentioned folding apparatus further comprises a support member that supports the folded sheets placed on the placement surface and is slidable in a stacking direction of the plurality of folded sheets on the placement surface. <1> or the above <4> 10. The sheet stacking device according to claim 9, wherein: <6> a pressure sensor that detects a pressure applied to the support member by the folded sheet placed on the placement surface; and a controller that slides the support member so that the pressure detected by the pressure sensor falls within a predetermined range. <5> 2 is a sheet stacking device according to the first embodiment. <7> The placing section is characterized in that it has a locking protrusion that protrudes from an end of the placing surface that is closer to the rotating body and that locks the folded sheets placed on the placing surface. <5> or the above <6> 2 is a sheet stacking device according to the first embodiment. <8> a sheet folding device that performs a folding process on a folded sheet; The folded sheets that have been subjected to the folding process by the sheet folding device are stacked. <1> or the above <7> and a sheet stacking device according to any one of the above. <9> an image forming device that forms an image on a sheet; a sheet folding device that performs a folding process on the sheet on which the image has been formed by the image forming device; The sheet folding device stacks folded sheets. <1> or the above <7> and a sheet stacking device according to any one of the above.

[0084] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0085] 1,1A: Image forming system 100: Image forming device 200: Sheet folding device 300, 300A: Sheet stacking device 310: Tray 311: Placement surface 312: Folding screen 313: Drive pulley 314: Driven pulley 315: Endless circular belt 316: Slide motor 317: Locking protrusion 318: Pressure sensor 320: Rotating body 321: Storage groove 322:Inner wall 323: Exterior wall 324: Rotary motor 330, 340: Guide member 331: Rotating shaft 332: Air cylinder 341: Guide motor 500: Controller [Prior art documents] [Patent documents]

[0086] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-051573

Claims

1. In a sheet stacking device for stacking folded sheets that have been folded by a sheet folding device, a loading section having a loading surface on which the folded sheet is placed; a rotating body that stores the folded sheet discharged from the sheet folding device in an arc-shaped storage groove and rotates to turn the folded sheet to a direction intersecting the placement surface and place the folded sheet on the placement surface; A sheet stacking device characterized by comprising a guide member provided on an outer wall defining the outer peripheral surface of the storage groove, the guide member moving between a contact position where it contacts the folded sheets stored in the storage groove and a separation position where it is separated from the folded sheets stored in the storage groove.

2. The sheet stacking device according to claim 1, characterized in that the guide member rotates around a rotation axis supported by the outer wall and extending in the width direction of the folded sheet between the contact position where the tip approaches the inner surface of the storage groove and the separated position where the tip moves away from the inner surface of the storage groove.

3. a controller for controlling the position of the guide member in accordance with the position of the folded sheet and the rotation angle of the rotating body; The controller When a leading edge of the folded sheet discharged from the sheet folding device passes a position where the leading edge can contact the guide member at the contact position, the guide member is rotated to the contact position, 3. The sheet stacking device according to claim 2, wherein the guide member is rotated to the separated position when the opening of the accommodation groove that accommodates the folded sheet faces the sheet stacking section.

4. The sheet stacking device according to claim 1, characterized in that the guide member slides between the contact position where it protrudes from the tip of the outer wall to increase the groove depth of the storage groove and the separated position where it retracts into the storage groove to decrease the groove depth of the storage groove.

5. 2. The sheet stacking device according to claim 1, further comprising a support member that supports the folded sheets placed on the placement surface and is slidable in the stacking direction of the plurality of folded sheets on the placement surface.

6. a pressure sensor that detects a pressure applied to the support member by the folded sheet placed on the placement surface; 6. The sheet stacking device according to claim 5, further comprising a controller that slides the support member so that the pressure detected by the pressure sensor falls within a predetermined range.

7. 6. The sheet stacking device according to claim 5, wherein the loading section includes a locking protrusion that protrudes from an end of the loading surface that is closer to the rotating body and that locks the folded sheets loaded on the loading surface.

8. a sheet folding device that performs a folding process on a folded sheet; 2. A sheet processing apparatus comprising: a sheet stacking device according to claim 1, which stacks the folded sheets that have been subjected to the folding process by the sheet folding device.

9. an image forming device that forms an image on a sheet; a sheet folding device that performs a folding process on the sheet on which the image has been formed by the image forming device; 2. An image forming system comprising: a sheet stacking device according to claim 1, which stacks folded sheets that have been subjected to the folding process by the sheet folding device.

Images