English Translation of PCT/CN2013/078732 PAPER MEDIUM STACKING DEVICE [0001] This application claims the benefit of priority to Chinese Patent Application No. 201210447728.X titled "SHEET-TYPE MEDIUM STACKING DEVICE", filed with the 5 Chinese State Intellectual Property Office on November 09, 2012, the entire disclosure of which is incorporated herein by reference. TECHNICAL FIELD [0002] The present application relates to a technique for processing a sheet-type medium, and particularly to a device for end-to-end stacking sheet-type medium piece by piece. 10 BACKGROUND [0003] A device for identifying financial bills piece by piece is generally required to be installed in the machine for processing financial bills, and after being identified piece by piece, the bills which are conveyed piece by piece are stacked to facilitate withdrawing the bills. For example, in a conventional automatic teller machine, multiple sheets of stacked banknotes are 15 sorted, conveyed and identified piece by piece, and then are stacked to be delivered out. At present, in a sheet-type medium stacking device, in which the medium is conveyed in a longitudinal direction, such as a banknote stacking device, a conveyor belt fits closely to an arc-shaped plate to convey a single sheet of banknote to a specific location to be stacked. For example, the first sheet of banknote is settled in the specific location, a front end of the 20 second sheet of banknote is superposed on a tail end of the first sheet of banknote, and the first sheet of banknote and the second sheet of banknote are clamped by the conveyor belt and the arc-shaped plate to move forwards together, and the first sheet of banknote stops moving forward when its front end reaches a predetermined blocking member. The second sheet of banknote is driven by the conveyor belt to overcome the frictional force between the 25 banknotes and continue to slide forward, and stops moving forward until it reaches the predetermined blocking member. The third sheet of banknote and subsequent banknotes go through the same process as the first and second sheets of banknotes, that is, the front end of a subsequent sheet of banknote is superposed on the tail end of a previous banknote and the banknotes are all conveyed to the predetermined blocking member, to be stacked. Eventually, - 1 - English Translation of PCT/CN2013/078732 the front ends of all the banknotes are aligned to the predetermined movable blocking plate, and a whole stack of banknotes are delivered to a predetermined position for an operator. [0004] However, in the above existing mechanism, starting from the second sheet of banknote, each sheet of banknote goes through the process of clinging to and rubbing against 5 a previous sheet of banknote. In this process, if the sheet of banknote has a slit at an angle to the advancing direction, the subsequent banknote is apt to be jammed at the slit, or if the sheet of banknote has a severe fold, the sheet of banknote is apt to be folded and arched at the fold, which may result in a banknote jam at the fold. SUMMARY 10 [0005] An object of the present application is to provide a sheet-type medium stacking device for effectively stacking sheet-type medium having a slit or being soft and old. [0006] The sheet-type medium stacking device includes: a piece-by-piece sheet-type medium conveying mechanism configured to convey a sheet-type medium piece by piece; 15 an upper conveyor belt configured to provide a driving force to the sheet-type medium and arranged around a driving transmission shaft and a driven transmission shaft which are arranged in a conveying direction of the sheet-type medium; an arc-shaped stacking plate configured to support the sheet-type medium, wherein an arc-shaped surface, fitting closely to the upper conveyor belt, of the arc-shaped stacking 20 plate defines a conveying passage for the sheet-type medium, a length of the conveying passage is at least greater than a length of one sheet of the sheet-type medium in the conveying direction, and one end of the conveying passage abuts the piece-by-piece sheet-type medium conveying mechanism and is slightly lower than a delivering outlet of the conveying mechanism, and another end of the conveying passage forms a discharging outlet 25 for a whole stack of sheet-type medium; a movable blocking mechanism arranged on a section of the conveying passage close to the discharging outlet and configured to selectively block the sheet-type medium; a sensor device arranged at a tail end of the delivering outlet of the piece-by-piece sheet-type medium conveying mechanism and configured to detect the arrival and passing of -2- English Translation of PCT/CN2013/078732 a sheet of the sheet-type medium; and a control unit configured to control the upper conveyor belt to move or stop moving according to information feedback from the sensor device; wherein, at least one pair of convex ribs are formed on a section, close to the 5 conveying mechanism, of the arc-shaped surface of the arc-shaped stacking plate at two sides of the upper conveyor belt, and a distance between the pair of convex ribs is smaller than the minimum dimension of the sheet-type medium in a direction perpendicular to the conveying direction. [0007] Preferably, the arc-shaped stacking device includes three sections, a section near the 10 piece-by-piece sheet-type medium conveying mechanism forms a rear arc-shaped plate, a section near the discharging outlet forms a front arc-shaped plate, and a middle section forms a reversing device. [0008] Furthermore, a recycling conveyor belt assembly and a discharging conveyor belt assembly are arranged below the reversing device and the front arc-shaped plate, wherein at 15 least a section of the recycling conveyor belt assembly fits with a section of the discharging conveyor belt assembly to form a recycling conveying passage for the sheet-type medium. [0009] Preferably, a floating pinch roller is provided on a side, away from the arc-shaped plate, of the upper conveyor belt at a position corresponding to the convex ribs, and is configured to increase a conveying force of the upper conveyor belt to the sheet-type medium. 20 [0010] Compared with the conventional technology, the valuable document identification device has the following advantages. [0011] By providing convex ribs on the arc-shaped stacking plate at the position corresponding to two sides of the upper conveyor belt, the sheet-type medium being clamped and conveyed forms a V shape, which greatly increases the rigidity of the sheet-type medium, 25 and effectively solves the problems of blockage caused by the slit at the tail of the sheet-type medium and blockage caused by folding and arching of soft and old medium. BRIEF DESCRIPTION OF THE DRAWINGS [0012] Figure 1 is a schematic view showing the structure of a sheet-type medium stacking device according to the present application; - 3- English Translation of PCT/CN2013/078732 [0013] Figure 2 is a schematic view of a stacking and recycling device of the sheet-type medium stacking device in Figure 1; [0014] Figure 3 is a partial schematic view of an arc-shaped stacking plate of the stacking and recycling device in Figure 2; 5 [0015] Figure 4 is a sectional view of the arc-shaped stacking plate in Figure 3; [0016] Figure 5 is a schematic view of the sheet-type medium stacking device in Figure 1 which is further provided with a floating roller; [0017] Figure 6 is a schematic view showing the depositing and withdrawing process of the sheet-type medium stacking device in Figure 1; 10 [0018] Figure 7 is a side view showing the stacking and recycling device in Figure 2 with a movable blocking plate in an open state and a reversing device at a second position; [0019] Figure 8 is an axonometric view of the stacking and recycling device in Figure 2; [0020] Figure 9 is a side view of a first conveyor belt assembly of the stacking and recycling device in Figure 2; 15 [0021] Figure 10 is an axonometric view of a second conveyor belt assembly and a third conveyor belt assembly of the stacking and recycling device in Figure 2; [0022] Figure 11 is a side view of the second conveyor belt assembly and the third conveyor belt assembly of the stacking and recycling device in Figure 2; [0023] Figure 12 is a side view of the second conveyor belt assembly and the third 20 conveyor belt assembly of the stacking and recycling device in Figure 2 when the floating support is at a second position; [0024] Figure 13 is a flow diagram showing the stacking and recycling device conveying a first sheet of banknote and a second sheet of banknote; [0025] Figure 14 is a schematic view of a control system of the sheet-type medium stacking 25 device in Figure 1; [0026] Figure 15 is a sectional schematic view of a sheet-type medium at the position of convex ribs of the arc-shaped stacking plate in the stacking process; [0027] Figure 16 is a schematic view showing banknotes being stacked and aligned in the -4- English Translation of PCT/CN2013/078732 stacking and recycling device in Figure 2; and [0028] Figure 17 is a schematic view showing a whole stack of banknotes being delivered out by the stacking and recycling device in Figure 2. DETAILED DESCRIPTION 5 [0029] For further illustrating the sheet-type medium stacking device according to the present application and clearly describing the structure and operation process of the device, a deposit machine used in a financial self-service equipment is described as an example. [0030] Reference is made to Figure 1, which is a schematic view showing the structure of a sheet-type medium stacking device (a deposit machine). The deposit machine has a depositing 10 port 101, a sheet separating device 1, a sheet tilt correction device 2, a sheet identifying device 3, a temporary storage device 4, a stacking and recycling device 5 and a storage box 6. The sheet separating device 1 separates banknotes at the depositing port 101 piece by piece and delivers the separated banknotes into the deposit machine. The sheet tilt correction device 2 is configured to adjust the banknotes inclined with respect too an advancing direction and 15 align the banknotes with a datum plane in parallel with the advancing direction. The sheet identifying device 3 is configured to identify the authenticity, the face value, the obverse and reverse, and the condition of banknotes and checks and to detect whether the sheets are conveyed abnormally, such as being titled, overlapped or continuous, to determine whether the sheets can be stored. The temporary storage device 4 is configured to temporarily store 20 banknotes or checks which are identifiable and are determined as being conveyed normally. The stacking and recycling device 5 is configured to stack banknotes or checks, to deliver out returned banknotes or checks, and to recycle the banknotes or checks that customers forget to withdraw. Conveying mechanisms 102, 103, 104 and 105 for conveying sheet-type medium piece by piece are provided between the above devices to convey banknotes. 25 [0031] Reference is made to Figure 2. The stacking and recycling device 5 includes an upper conveyor belt 153 for providing a driving force to the sheet-type medium, an arc-shaped stacking plate for supporting the sheet-type medium, a movable blocking mechanism 20 for selectively blocking the sheet-type medium, a sensor device 17 and a control unit. The upper conveyor belt 153 is arranged around a driving transmission shaft 151 30 and a driven transmission shaft 156 which are arranged in a conveying direction of the -5- English Translation of PCT/CN2013/078732 sheet-type medium. The arc-shaped stacking plate includes three sections; the section, near the conveying mechanism for conveying sheet-type medium piece by piece, forms a rear arc-shaped plate 18; the section near a medium discharging outlet forms a front arc-shaped plate 19; and the middle section forms a reversing device 25. The upper conveyor fits closely 5 to the arc-shaped surface of the arc-shaped stacking plate, thereby forming a conveying passage for the sheet-type medium. The length of the conveying passage is at least greater than that the length of one sheet of the sheet-type medium in the conveying direction. One end of the conveying passage abuts the conveying mechanism 105 for conveying sheet-type medium piece by piece and is slightly lower than a delivering outlet of the conveying 10 mechanism. Another end of the conveying passage forms the discharging outlet for a whole stack of sheet-type mediums. The movable blocking mechanism 20 is arranged on a section of the conveying passage close to the discharging outlet. The sensor device 17 is arranged at the tail end of the delivering outlet of the conveying mechanism for conveying sheet-type medium piece by piece and is configured to detect the arrival and passing of a sheet of the 15 sheet-type medium. The control unit is configured to control the upper conveyor belt 153 to move or stop moving according to the information feedback from the sensor device 17, thereby connecting the adjacent sheet-type mediums, entering into the arc-shaped stacking device, end to end. For facilitating discharging or recycling the whole stack of sheet-type medium, corresponding to the three-section design of the arc-shaped plate, a first conveyor 20 belt assembly 15 is provided corresponding to the upper conveyor belt 153, a second conveyor belt assembly 22 is provided corresponding to the front arc-shaped plate 19, and a third conveyor belt assembly 23 is provided corresponding to the reversing device 25. [0032] Reference is made to Figure 3 and Figure 4. Two pairs of convex ribs 183, 184 are formed on a section of the arc-shaped surface of the rear arc-shaped plate 18 at two sides of 25 the upper conveyor belt 153. A distance between each pair of convex ribs 183, 184 is smaller than the minimum dimension of the sheet-type medium in a direction perpendicular to the conveying direction. Reference is made to Figure 5. To increase the conveying force of the upper conveyor belt to the sheet-type medium at the position of the convex ribs, a floating pinch roller 30 is provided on a side, away from the arc-shaped plate 18, of the upper 30 conveyor belt at a position corresponding to the convex ribs 183, and is fixed at an end of a floating plate 32 via a mandrel 31. The floating plate 32 is pivotally mounted on a mandrel 33. [0033] Referring to Figure 1, the specific working process of the deposit machine is -6- English Translation of PCT/CN2013/078732 illustrated herein. When depositing, a customer puts one or more sheets of banknotes at the depositing port 101, and the banknotes are separated by the sheet separating device 1 piece by piece and then passes through the sheet tilt correction device 2 and the sheet identifying device 3. The banknotes determined to be normal and the face value of which has been 5 identified or the checks which are identifiable enter into the temporary storage device 4 via a route 102. The banknotes or checks which are unidentifiable are returned to the stacking and recycling device 5 via a route 103 and a routine 105, and then are aligned and stacked at the stacking unit 51, and the returned banknotes are stacked and then delivered out after the banknotes at the depositing port 101 are completely separated. When it is determined that the 10 returned banknotes or checks are not withdrawn by the operator in a specific time, the banknotes or checks are recycled to the recycling unit 52. [0034] Referring to Figure 6, the banknotes depositing and returning process of the deposit machine is described herein. After the banknotes are completely separated piece by piece, the banknotes detected determined to be normal and the face value of which has been identified 15 are conveyed into the temporary storage device 4, at this time, if the customer confirms depositing, the banknotes are conveyed out of the temporary storage 4 and then conveyed into the storage box 6 via a routine 104, thereby implementing the banknotes depositing process. If the customer cancels depositing, the banknotes are conveyed out of the temporary device 4 and conveyed to the stacking and recycling device 5 via the routine 105, and then are aligned 20 and stacked in the stacking unit 51, and finally are stacked and then delivered out, thereby implementing the banknotes returning process. When it is determined that the returned banknotes are not withdrawn by the customer in a specific time, the banknotes are recycled to the recycling unit 52. [0035] Reference is made to Figure 2 and Figure 7. The banknotes are returned via the 25 routine 105 and are clamped between an upper delivering conveyor belt 11 and a lower delivering conveyor belt 12 piece by piece to be conveyed to the stacking and recycling device 5. An upper guiding board 13 and a lower guiding board 14 are arranged in the advancing direction of the discharged banknotes. The first conveyor belt assembly 15 arranged in parallel to the advancing direction of the banknotes is provided in front (the 30 rightward direction in the figures) of the upper guiding board 13. A first sensor device 17 is arranged between the driving roller 151 and the delivering roller 16, and is configured to detect each sheet of discharged banknote. The rear arc-shaped plate 18, the front arc-shaped -7- English Translation of PCT/CN2013/078732 plate 19 and the reversing device 25 which have similar curvatures are provided below the first conveyor belt assembly 15, and a rear-end plane 181 of the rear arc-shaped plate 18 is obviously lower than the outlet (a port for discharging the banknotes) formed between the upper delivering conveyor belt 11 and the lower delivering conveyor belt 12. Above the front 5 section of the front arc-shaped plate 19, the movable blocking plate 20 is pivotally mounted on a mandrel 152 and has two working states, including a closed state as shown in Figure 2 and an open state as shown in Figure 7. A second sensor device 21 is fixed in front of the movable blocking plate 20 and is configured to detect the presence of banknotes in front of the movable blocking plate 20 and above the front arc-shaped plate 19. The adjustable second 10 conveyor belt assembly 22 is arranged below the front arc-shaped plate 19, and the third conveyor belt assembly 23 is arranged at a corresponding position at the rear end of the second conveyor belt assembly 22. The first conveyor belt assembly 15, the second conveyor belt assembly 22 and the third conveyor belt assembly 23 are driven by the same power. A storage container 24 is arranged below the recycling unit 52, and an inlet of the storage 15 container 24 is corresponding to a conveying port formed by a recycling floating roller 221 of the second conveyor belt assembly 22 and a driving roller 231 of the third conveyor belt assembly 23. The reversing device 25 is arranged between the rear arc-shaped plate 18 and the front arc-shaped plate 19 and above the conveying port formed by the recycling floating roller 221 and the driving roller 231, and is pivotally mounted on a mandrel 26, and has two 20 working states, including a first position as shown in Figure 2 and a second position as shown in Figure 7. [0036] Referring to Figure 8 and Figure 9, the first conveyor belt assembly 15 is illustrated in detail. A first conveyor belt 153 (that is the upper conveyor belt) of the first conveyor belt assembly 15 is arranged around the driving roller 151, a roller 154, a roller 155 and the pinch 25 roller 156. The lower section of the first conveyor belt 153 is tensed by the upper surfaces of the rear arc-shaped plate 18 and the front arc-shaped plate 19. The pinch roller 156 is fixed at the front end of the pressing plate 158 via a mandrel 157, and the pressing plate 158 is swingable around the mandrel 152. [0037] Referring to Figures 10 to 12, the second conveyor belt assembly and the third 30 conveyor belt assembly of the stacking and recycling device are illustrated. Two abreast second conveyor belts 222 of the second conveyor belt assembly 22 are arranged around the recycling floating roller 221, the second driving roller 223, a second pinch roller 224 and a -8- English Translation of PCT/CN2013/078732 tensioning roller 225. The second pinch roller 224 is directed to the pinch roller 156 of the first conveyor belt assembly 15. The recycling floating roller 221 is mounted on a recycling floating support 226 through a pair of bearings and is swingable around a mandrel 227. A banknote-delivering floating support 229 swingable around a mandrel 228 is mounted at a 5 front end of the second conveyor belt assembly 22, and has two working states, including a first position as shown in Figure 11 and a second position as shown in Figure 12. The swinging of the delivering floating support 229 and the movable blocking plate 20 are driven by the same power. The delivering floating support 229 is provided with two rows of roller sets 230 corresponding to the second conveyor belt 222. The roller sets 230 may make the 10 working surface of the second conveyor belt 222 higher or lower than the upper arc-shaped surface of the front arc-shaped plate 19 through the swinging of the delivering floating support 229. A third conveyor belt 233 of the third conveyor belt assembly 23 is arranged around a third driving roller 232 and the third driven roller 231. [0038] Referring to Figures 13 to 17, the process for realizing the function of the stacking 15 and recycling device is illustrated. When the banknotes are to be returned, the movable blocking plate 20 is in the closed state as shown in Figure 13, to prevent the banknotes from moving in the advancing direction of banknotes. The delivering floating support 229 is in the first position, to make the working surface of the upper section of the second conveyor belt 222 lower than the upper arc-shaped surface of the front arc-shaped plate 19, thus, when 20 slipping along the arc-shaped plate, the banknotes will not contact the working surface of the second conveyor belt 222. The reversing device 25 is in the first position, to allow the banknotes to pass along the arc-shaped surface smoothly. The first sheet of banknote 27 is delivered out by the upper delivering conveyor belt 11 and the lower delivering conveyor belt 12, the front end of the banknote passes through the first sensor device 17 (an acquisition 25 module), the sensor 17 feeds back an information to a processing module of the control system, and the processing module processes the information and then sends out a signal, to start a first driving motor (an execution module) immediately or start the first driving motor after a period of time, thereby driving the first conveyor belt assembly 15, the second conveyor belt assembly 22 and the third conveyor belt assembly 23 to rotate in the direction 30 shown in Figure 13. The first conveyor belt assembly 15 cooperates with the rear arc-shaped plate 18 to convey the banknote forward, the sensor 17 feeds back an information to the processing module of the control system when the tail end of the banknote leaves the first -9- English Translation of PCT/CN2013/078732 sensor device 17, and the processing module processes the information and sends out a signal to stop the first driving motor, and in this case, all of the conveyor belt assemblies are stopped, the banknote stops at position 182 with the tail end being exposed behind the first conveyor belt assembly 15. The front end of the first sheet of banknote 27 reaches the first pair of 5 convex ribs 183 and the second pair of convex ribs 184. As shown in Figure 15, due to the action on the front end of the first sheet of banknote 27 from the first conveyor belt 153, the first pair of convex ribs 183 and the second pair of convex ribs 184, the first sheet of banknote 27 is bent upward at two sides of the advancing direction, thus the section, perpendicular to the advancing direction, of the banknote forms a V shape. When the second sheet of banknote 10 28 is delivered out, the front end of the second sheet of banknote passes through the first sensor device 17, the first sensor device 17 feeds back an information to the control system, and the control system sends out a signal for starting the first driving motor, to start the first driving motor immediately or after a period of time, thereby driving the first conveyor belt assembly, the second conveyor belt assembly and the third conveyor belt assembly to rotate in 15 the direction shown in Figure 13. The front end of the second sheet of banknote 28 is superposed on the tail end of the first sheet of banknote 27, and the two sheets of banknotes which are partially overlapped are conveyed forward together by the first conveyor belt assembly 15. After the tail end of the second sheet of banknote leaves the first sensor device 17, the first sensor device 17 feeds back information to the control system, and the control 20 system stops the first driving motor, and the second sheet of banknote stops at the position 182. The third sheet of banknote and the subsequent banknotes are conveyed in the same manner, in which the front end of a subsequent sheet of banknote is superposed on the tail end of a previous sheet of banknote. When the front end of the first sheet of banknote 27 reaches the movable blocking plate 20, the banknote is prevented from moving forward, and slips 25 with respect to the first conveyor belt 153. The action force on the banknotes from the first conveyor belt 153 is greater than the frictional force between the banknotes, thereby making the second sheet of banknote 28 and the first sheet of banknote 27 rub against each other to be aligned to the movable blocking plate 20. The rubbing process is illustrated as follow. Under the action of the first conveyor belt 153, the first pair of convex ribs 183 and the second pair 30 of convex ribs 184, the second sheet of banknote 28 is bent upward at two side of the advancing direction, thereby making the section, perpendicular to the advancing direction, of the banknote form a V shape. The two sides of the second sheet of banknote 28 being bent -10- English Translation of PCT/CN2013/078732 upward makes the two sides of the second sheet of banknote 28 higher than the two sides of the first sheet of banknote 27, which intensifies the strength of the banknotes in the advancing direction. Therefore, when the second sheet of banknote 28 or the first sheet of banknote 27 have slits, the slits can be avoided in a certain extent. And if the banknote is blocked at the slit, 5 the first conveyor belt 153 can provide an enough conveying force for the second sheet of banknote 28, to allow the second sheet of banknote 28 to cross the slit without being folded and arched. As shown in Figure 16, the third sheet of banknote and the subsequent banknotes go through the same process, and the front ends thereof are eventually aligned to the movable blocking plate 20. 10 [0039] After all of the banknotes are delivered out, that is, the banknotes have been processed, the control system sends out a signal to control the second motor, to shift the movable blocking plate 20 to the open state as shown in Figure 17, thereby removing the blockage in the advancing direction of the banknotes. Meanwhile, the delivering floating support 229 is shifted to the second position to make the working surface of the second 15 conveyor belt 222 higher than the upper arc-shaped surface of the front arc-shaped plate 19, thus the working surface of the second conveyor belt 222 is in contact with the banknotes. The first driving motor is started to drive the first conveyor belt assembly, the second conveyor belt assembly and the third conveyor belt assembly to rotate in the direction shown in Figure 17. The banknotes are clamped between the first conveyor belt assembly 15 and the 20 second conveyor belt assembly 22 to be delivered out, and the pressing plate 158 may automatically adjust the gap between the pinch roller 156 and the second pinch roller 224 according to the total thickness of the banknotes. According to the time counting of the controlling program, the transmission structure stops the conveyor belts when the banknotes are delivered out for a certain distance, and the tail ends of the banknotes are clamped 25 between the pinch roller 156 and the second pinch roller 224, thereby accomplishing the delivering process. In the case that the whole stack of the delivered banknotes haven't been withdrawn by the operator timely, the movable blocking plate 20 and the reversing device 25 of the stacking and recycling device are shifted to the position as shown in Figure 7, the control system controls the first conveyor belt assembly, the second conveyor belt assembly 30 and the third conveyor belt assembly to rotate in the reversed direction, and the whole stack of banknotes are conveyed reversely under the action of the first conveyor belt assembly and the second conveyor belt assembly and guided into the recycling box 52 by the reversing device -11- English Translation of PCT/CN2013/078732 25 in the reverse conveying process. [0040] The embodiments described hereinabove are only preferred embodiments of the present application, and should not be interpreted as limitation to the present application. The technical solutions claimed by the present application not only can be applied to the financial 5 field for processing banknotes, but also can process checks or other whole stack of sheet-type medium which are required to be separated piece by piece. Therefore, for those skilled in the art, a few of modifications and improvements may be made without departing from the spirit and scope of the present application, and theses modifications and improvements are also deemed to fall into the scope of the present application. - 12 -