Banknote foreign object detection using pressure sensing array

[0012] Foreign objects may damage one or more banknote processing elements inside the ATM. For example, if two or more banknotes are stapled together, the staples may clog the mechanism that processes the banknotes one at a time. As another example, a rubber band surrounding two or more banknotes may also block the processing mechanism.

[0013] To detect these foreign objects, the system discussed below can apply pressure to a stack of banknotes. Any foreign objects with significant thickness, such as paper clips, staples or rubber bands, can appear as areas with relatively high pressure. For example, when a stack of banknotes is under pressure, the staples at the corners of a banknote can form a relatively high pressure area at the corners of the stack.

[0014] In some examples, the automated teller machine may use a pressure sensor array such as a piezoresistive sensor to detect the presence of foreign objects such as staples, paper clips, or rubber bands in a stack of banknotes. The user can insert a stack of banknotes into the ATM. A pair of opposed gripping surfaces can apply pressure to the stack of banknotes. The pressure sensor array on one or both of the clamping surfaces can sense the unevenness of the pressure in the array area. If the circuit coupled to the pressure sensor senses the presence of a high pressure area in the surface area of ​​the banknote, the circuit may generate a signal indicating that one or more foreign objects have been detected. The automated teller machine may then prompt the user to remove the stack of banknotes and remove the foreign object from the stack of banknotes.

[0015] The use of pressure sensors to detect foreign objects in a stack of banknotes can improve the prior art. For example, a metal detector can detect staples and metal paper clips, but it may not find rubber bands or plastic paper clips in a stack of banknotes. Other technologies, such as X-ray imaging, may be too expensive or complicated.

[0016] figure 1 An example of a system 100 that can detect the presence of foreign objects in a stack of banknotes 102 according to some embodiments is shown. In some examples, the system 100 can act as an automated teller machine. In other examples, the system 100 can serve as any suitable device that can receive a stack of banknotes or other documents. figure 1 The configuration of is only an example; other configurations can also be used.

[0017] The system 100 can include a housing 104. In some examples, the housing 104 may include the exterior of an automated teller machine or the like. In other examples, the housing 104 may form part of the interior of the device, such as a compartment within the device.

[0018] The housing 104 may have a port 106 sized and shaped to receive a stack of banknotes 102. In some examples, the user can insert a stack of banknotes 102 into the housing 104 through the port 106. In some examples, the housing 104 may include a movable door 108 that can open and close the port 106. In other examples, the user can insert a stack of banknotes 102 into the port 106, wherein the gripping assembly can grasp the banknote 102 and transport the banknote 102 to a location inside the housing 104. The gripping assembly can be coupled to rollers, belts, and/or other suitable mechanisms that can transport the banknote 102 within the device.

[0019] A pair of opposite clamping surfaces 110 may be positioned inside the housing 104. The relative clamping surface 110 can apply pressure to the stack of banknotes 102 in a controlled manner. In some examples, one clamping surface of the pair of opposing clamping surfaces 110 may be held in a fixed position, and the actuator 112 may make the other clamping surface of the pair of opposing clamping surfaces 110 face The fixed clamping surface moves. In other examples, the opposing clamping surfaces 110 may move toward each other, with an actuator 112 coupled to each clamping surface. The actuator or actuators 112 can apply sufficient force or pressure to sense the presence of foreign objects in the stack of banknotes 102, but the pressure is not sufficient to crush or damage the foreign objects.

[0020] Pressure sensor 202 array 200 (see figure 2 ) May be positioned on at least one of the pair of opposite clamping surfaces 110. The pressure sensor 202 array 200 can measure the pressure exerted on the surface area of ​​the stack of banknotes 102. In some examples, the array 200 may have sufficient resolution to locate foreign objects to specific quadrants of the banknote. In other examples, the array 200 may include a resolution of ten pressure sensors 202 on one side, eighteen pressure sensors 202 on one side, thirty pressure sensors 202 on one side, or more than thirty pressure sensors 202 on one side. In some examples, the array 200 may be two-dimensional, with different numbers of pressure sensors 202 along its two dimensions. In some examples, the pressure sensors 202 in the array 200 are piezoresistive sensors. Piezoresistive sensors are particularly suitable for sensing pressure due to their stability over time and their long life expectancy. Other pressure sensors 202 may also be used, including strain gauges manufactured by chemical vapor deposition, strain gauges manufactured by sputtering thin films, variable capacitance solid-state strain gauges manufactured using micro-machined silicon, and the like.

[0021] The circuit 114 may be positioned in the housing 104 and coupled to the pressure sensor array. In some examples, the circuit 114 may include a processor, a memory, and instructions stored in the memory and executable on the processor. In some examples, the circuit 114 may include one or more dedicated processors or chips that can execute instructions hard-wired into the processors or chips. In some examples, the circuit 114 may receive and process electrical signals from the pressure sensor. In the case where the pressure sensor is a piezoresistive sensor, the circuit 114 can drive the piezoresistive sensor, can receive pressure measurement values ​​from the piezoresistive sensor, and can process multiple pressure measurement values ​​obtained from the pressure sensor array as needed.

[0022] The circuit 114 can determine whether the pressure sensor array senses the presence of a high pressure area in the surface area of ​​the banknote. The circuit 114 may further generate a signal in response to sensing the high voltage area, indicating that one or more foreign objects have been detected in the stack of banknotes. Such signals may include voltage or current pulses, higher voltages, or internal signals that the processor can use to trigger additional actions, such as opening the door 108 on port 106, returning the wad of banknotes through port 106, and/or The user displays a message that the wad of banknotes 102 is removed, the foreign objects are removed from the wad of banknotes 102, and the wad of banknotes 102 is returned to the port 106. Other suitable signals can also be used.

[0023] There are many possible techniques to sense the presence of high-pressure areas in the surface area of ​​the banknote based on the data returned from the pressure sensor array. Two specific examples are provided below; other suitable techniques can also be used.

[0024] In the first example, the circuit 114 can detect the maximum pressure sensed on the pressure sensor array, detect the minimum pressure sensed on the pressure sensor array, and compare the maximum pressure sensed with the minimum pressure sensed. The difference between is compared with the specified threshold. If the difference exceeds the specified threshold, the circuit 114 can determine that there is a high-voltage area in the surface area of ​​the banknote and can take subsequent actions. The subsequent actions may include prompting the user to remove the wad of banknotes 102 through the port 106 and remove foreign objects from the wad of banknotes 102.

[0025] In the second example, the circuit 114 may calculate the pressure gradient based on the pressure sensed on the pressure sensor array, calculate the maximum value of the absolute value of the pressure gradient on the pressure sensor array, and compare the calculated maximum value with a specified threshold. If the calculated maximum value exceeds the specified threshold, the circuit 114 can determine that there is a high-voltage area in the surface area of ​​the banknote and can take subsequent actions. The subsequent actions may include prompting the user to remove the wad of banknotes 102 through the port 106 and remove foreign objects from the wad of banknotes 102.

[0026] If the circuit 114 does not sense the presence of a high-voltage area in the surface area of ​​the banknote 102 (for example, the circuit senses that there is no high-voltage area in the surface area of ​​the banknote 102), the circuit 114 can activate the processing mechanism 116 in the housing 104, It can receive the wad of banknotes 102 from the pair of opposed holding surfaces 110. The processing mechanism 116 can mechanically process the banknotes in the stack of banknotes 102 one at a time. The processing mechanism 116 can determine the denomination of each banknote, can check the authenticity of each banknote, and so on.

[0027] The above two examples are just examples. Or, other suitable detection techniques can be used to determine whether there is a high pressure area in the surface area of ​​the banknote based on the pressure value measured by the pressure sensor array.

[0028] figure 2 An example of an array 200 of pressure sensors 202 superimposed on the dashed outline of a banknote 204 according to some embodiments is shown. in figure 2 In an example, in a stack of banknotes, the paper clip 206 may extend beyond the edge of one or more banknotes 204. When pressure is applied to the stack of banknotes 204 against the clamping surface, the paper clip 206 can increase the pressure in the subgroup 208 of the pressure sensor 202 array 200. In other words, the paper clip 206 may form a high pressure area extending on the subgroup 208 of the pressure sensor 202. figure 2 The paper clip 206 is only an example of a foreign object; staples, rubber bands, or other foreign objects can also generate similar high-pressure areas.

[0029] In some examples, the pressure sensor 202 array 200 may extend over a surface area greater than the surface area of ​​the stack of banknotes 204. For example, the linear size of the surface area of ​​the pressure sensor 202 array 200 may be greater than the comparative linear size of the surface area of ​​the stack of banknotes 204. For these examples, the array 200 may extend beyond a certain edge of the banknote 204 by some pixels (e.g., a single pressure sensor 202 in the array 200) or full pixels or more. In some examples, pixels or pixel portions that extend beyond the edge of the surface area of ​​the banknote 204 can be appropriately calibrated by the circuit when determining whether there is a high voltage area. Such calibration may include the relative fraction of the surface area on the banknote 204 and the fraction of the surface area beyond the edge of the banknote 204.

[0030] image 3 An example of a method 300 for detecting the presence of foreign objects in a stack of banknotes according to some embodiments is shown. The method 300 can be performed by an automated teller machine or by other suitable devices that can receive a stack of banknotes.

[0031] At operation 302, the automated teller machine may receive a stack of banknotes through the housing port.

[0032] At operation 304, the automated teller machine may apply pressure to the stack of banknotes using a pair of opposed gripping surfaces located inside the housing.

[0033] At operation 306, the automated teller machine may use a pressure sensor array positioned on at least one of the pair of opposed clamping surfaces to measure the pressure exerted on the surface area of ​​the stack of banknotes. In some examples, the pressure sensor array may extend over a surface area that is greater than the surface area of ​​the stack of bills. In some examples, the linear dimension of the surface area of ​​the pressure sensor array may be greater than the control linear dimension of the surface area of ​​the stack of banknotes. In some examples, the pressure sensors in the array may be piezoresistive sensors.

[0034] At operation 308, the automated teller machine may sense the presence of a high pressure area in the surface area of ​​the banknote using a circuit coupled to the pressure sensor array. In some examples, operation 408 may include: detecting the maximum pressure sensed on the pressure sensor array; detecting the minimum pressure sensed on the pressure sensor array; and determining the maximum pressure sensed and the minimum sensed pressure The difference between the pressures exceeds the specified threshold. In some examples, operation 408 may include: calculating the pressure gradient based on the pressure sensed on the pressure sensor array; calculating the maximum value of the absolute value of the pressure gradient on the pressure sensor array; and determining the maximum value of the absolute value of the pressure gradient The value exceeds the specified threshold.

[0035] At operation 310, the automated teller machine may use the circuit to generate a signal indicating that one or more foreign objects have been detected in the stack of banknotes. In some examples, operation 310 may include prompting the user to remove the wad of banknotes through the port and remove foreign objects from the wad of banknotes.

[0036] It is instructive to detail what might happen when the system checks but does not look for the high-voltage area in the wad of banknotes.

[0037] This system may include a housing with a port configured to receive a stack of banknotes. The actuator can move at least one clamping surface of the pair of opposed clamping surfaces toward the other clamping surface of the pair of opposed clamping surfaces, thereby controllably applying pressure to the stack of banknotes. A pressure sensor array positioned on at least one of the pair of opposed clamping surfaces can measure the pressure exerted on the surface area of ​​the stack of bills.

[0038] A circuit positioned in the housing and coupled to the pressure sensor array can sense the absence of high pressure areas in the surface area of ​​the banknote. For example, the circuit can detect the maximum pressure sensed on the pressure sensor array, detect the minimum pressure sensed on the pressure sensor array, and determine the difference between the maximum pressure sensed and the minimum pressure sensed. The difference does not exceed the specified threshold. As another example, the circuit can calculate the pressure gradient based on the pressure sensed on the pressure sensor array, calculate the maximum absolute value of the pressure gradient on the pressure sensor array, and determine that the maximum absolute value of the pressure gradient does not exceed Specify the threshold.

[0039] Once the circuit senses that there is no high-voltage area in the surface area of ​​the banknote, the circuit can determine that there is no foreign matter in the wad of banknotes. Banknotes can then be processed. For example, the processing mechanism may receive the wad of banknotes from the pair of opposed gripping surfaces and mechanically process the banknotes in the wad of banknotes one at a time.

[0040] Figure 4 A block diagram showing an example of a terminal 400 such as an automated teller machine according to some embodiments. Figure 4 The example of is only one configuration of the terminal; other configurations can also be used.

[0041] In one embodiment, multiple such terminals 400 are utilized in a distributed network to implement multiple components in a transaction-based environment. Object-oriented, service-oriented, or other architectures may be used to implement such functions and communicate between multiple terminals 400 and components.

[0042] An example of a terminal 400 in the form of a computer 410 may include a processing unit 402, a memory 404, a removable storage device 412, and a non-removable storage device 414. The memory 404 may include a volatile memory 406 and a non-volatile memory 408. The computer 410 may include or have access to a computing environment that includes various computer-readable media, such as volatile memory 406 and non-volatile memory 408, removable storage device 412, and non-removable storage device 414. Computer storage devices include random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM), flash memory or other memories Technology, compact disc read-only memory (CD ROM), digital versatile disc (DVD) or other optical storage device, tape cassette, magnetic tape, magnetic disk storage or other magnetic storage device, or any other medium capable of storing computer readable instructions. The computer 410 may include or have access to a computing environment including an input 416, an output 418, and a communication connection 420. The computer can use a communication connection to connect to one or more remote computers such as a database server to operate in a networked environment. The remote computer may include a personal computer (PC), a server, a router, a network PC, a peer-to-peer device, or other common network nodes, and so on. The communication connection may include a local area network (LAN), a wide area network (WAN) or other networks.

[0043] The computer-readable instructions stored on the computer-readable medium can be executed by the processing unit 402 of the computer 410. Hard drives, CD-ROMs, and RAMs are some examples of items that include non-transitory computer-readable media. For example, according to the teachings of the present disclosure, a computer program 422 having instructions for the computer 410 may be included on a CD-ROM and loaded from the CD-ROM to a hard drive. The computer readable instructions allow the computer 410 to provide general access control in a COM-based computer network system with multiple users and servers.

[0044] According to Example 1 of the present disclosure, a system is disclosed, which includes: a housing having a port that is sized and shaped to receive a stack of banknotes; and a pair of opposed gripping surfaces that are positioned inside the housing and configured to be able to Controllably applying pressure to the stack of banknotes; a pressure sensor array positioned on at least one of the pair of opposed clamping surfaces and configured to measure the pressure exerted on the surface area of ​​the stack of banknotes; and positioning A circuit in the housing, which is coupled to the pressure sensor array and is configured to: sense the presence of a high pressure area in the surface area of ​​the banknote; and generate a signal indicating that one or more foreign objects have been detected in the stack of banknotes.

[0045] According to optional example 2, the system according to example 1 is disclosed, wherein sensing the presence of a high pressure area includes: detecting the maximum pressure sensed on the pressure sensor array; detecting the minimum pressure sensed on the pressure sensor array; and determining The difference between the maximum pressure sensed and the minimum pressure sensed exceeds a specified threshold.

[0046] In addition, according to optional example 3, a system according to any of the foregoing examples is disclosed, wherein sensing the presence of a high-pressure region includes: calculating a pressure gradient based on the pressure sensed on the pressure sensor array; calculating the absolute value of the pressure gradient on the pressure sensor array The maximum value of the value; and determining that the maximum value of the absolute value of the pressure gradient exceeds the specified threshold.

[0047] In addition, according to optional example 4, a system according to any of the preceding examples is disclosed, wherein the circuit is further configured to prompt the user to remove the wad of banknotes through the port and remove foreign objects from the wad of banknotes.

[0048] Also according to optional example 5, a system according to any of the preceding examples is disclosed, wherein the pressure sensor array extends over a surface area greater than the surface area of ​​the wad of banknotes.

[0049] In addition, according to optional example 6, a system according to any of the preceding examples is disclosed, wherein the linear dimension of the surface area of ​​the pressure sensor array is greater than the control linear dimension of the surface area of ​​the wad of banknotes.

[0050] In addition according to optional example 7, a system according to any of the preceding examples is disclosed, further comprising an actuator coupled to the electric circuit and configured to cause at least one of the pair of opposed clamping surfaces Moving toward the other clamping surface of the pair of opposed clamping surfaces.

[0051] Also according to optional example 8, a system according to any of the preceding examples is disclosed, wherein the pressure sensors in the array are piezoresistive sensors.

[0052] A method according to Example 9 is disclosed, which includes: applying pressure to a stack of received banknotes by a pair of opposed clamping surfaces with a pressure sensor array inside, and when the stack of banknotes is sensed by the pressure sensor array After the high-voltage area in the surface area, it is detected that there is a foreign body in the wad of banknotes; and a signal is output indicating that at least the foreign body has been detected in the wad of banknotes.

[0053] According to optional example 10, the method according to example 9 is disclosed, wherein sensing the presence of a high-pressure area includes: detecting the maximum pressure sensed on the pressure sensor array; detecting the minimum pressure sensed on the pressure sensor array; and determining The difference between the maximum pressure sensed and the minimum pressure sensed exceeds a specified threshold.

[0054] In addition, according to optional example 11, the method according to any one of examples 9 to 10 is disclosed, wherein sensing the presence of a high-pressure region includes: calculating a pressure gradient based on the pressure sensed on the pressure sensor array; calculating the pressure on the pressure sensor array The maximum value of the absolute value of the pressure gradient; and it is determined that the maximum value of the absolute value of the pressure gradient exceeds the specified threshold.

[0055] In addition, according to optional example 12, the method according to any one of examples 9 to 11 is disclosed, further comprising: receiving the wad of banknotes through the port of the housing; and prompting the user to remove the wad of banknotes through the port and remove foreign objects from the wad of banknotes.

[0056] Also according to optional example 13, a method according to any one of examples 9 to 12 is disclosed, wherein the pressure sensor array extends over a surface area greater than the surface area of ​​the wad of banknotes.

[0057] In addition, according to optional example 14, the method according to any one of examples 9 to 13 is disclosed, wherein the linear dimension of the surface area of ​​the pressure sensor array is greater than the control linear dimension of the surface area of ​​the wad of banknotes.

[0058] Also according to optional example 15, a method according to any one of examples 9 to 14 is disclosed, wherein the pressure sensors in the array are piezoresistive sensors.

[0059] According to Example 16, a system is disclosed that includes: a housing having a port configured to receive a stack of banknotes; a pair of opposed gripping surfaces positioned inside the housing and configured to controllably apply pressure to the stack Banknotes; pressure sensor array positioned on at least one of the pair of opposed clamping surfaces and configured to measure the pressure exerted on the surface area of ​​the wad of banknotes; a circuit positioned in the housing, which Coupled to the pressure sensor array and configured to sense the absence of a high-pressure area in the surface area of ​​the banknote; and a processing mechanism configured to receive the wad of banknotes from the pair of opposed holding surfaces and mechanically process it one at a time Banknotes in a wad of cash.

[0060] According to optional example 17, the system according to example 16 is disclosed, wherein sensing the absence of a high pressure area includes: detecting the maximum pressure sensed on the pressure sensor array; detecting the minimum pressure sensed on the pressure sensor array; and It is determined that the difference between the maximum pressure sensed and the minimum pressure sensed does not exceed a specified threshold.

[0061] According to optional example 18, the system according to any one of examples 16 to 17 is disclosed, wherein sensing the absence of a high-pressure area includes: calculating a pressure gradient based on the pressure sensed on the pressure sensor array; calculating the pressure on the pressure sensor array The maximum value of the absolute value of the pressure gradient; and it is determined that the maximum value of the absolute value of the pressure gradient exceeds the specified threshold.

[0062] According to optional example 19, a system according to any one of examples 16 to 18 is disclosed, further comprising an actuator coupled to the electric circuit and configured to cause at least one of the pair of opposed clamping surfaces The clamping surface moves toward the other clamping surface of the pair of opposed clamping surfaces.

[0063] According to optional example 20, a system according to any one of examples 16 to 19 is disclosed, wherein: the pressure sensor array extends over a surface area larger than the surface area of ​​the wad of banknotes; the linear size of the surface area of ​​the pressure sensor array is greater than the wad of banknotes The contrast linear size of the surface area; and the pressure sensors in the array are piezoresistive sensors.