JP2013021894A - Non-contact charging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost non-contact charging system capable of recognizing identification information for a charged device and grasping a charging situation.SOLUTION: A charging device 1 has a charging circuit unit 12, an IC tag reader unit 14, an antenna 15, and a controller 11. A charged device 2 has a battery 24, a charging control circuit unit 23, a smoothing circuit unit 22, an IC tag unit 25, an antenna 26, and a switch 27 provided between the IC tag unit 25 and the antenna 26. The charging control circuit unit 23 has a function for making the switch 27 non-conductive when a power of the battery 24 exceeds a preliminarily-defined value, and making the switch 27 conductive when the power of the battery 24 is equal to or less than the value. An IC tag reader unit 14 performs an operation for reading identification information. The controller 11 has a function for starting a charging operation of the charging circuit unit 12 only when the identification information can be read out and the readout identification information is identical to the permitted identification information, and a function for stopping the charging operation when the identification information cannot be read out.

Description

  The present invention relates to a non-contact charging system that performs non-contact charging of a battery built in an electronic device or the like.

  Usually, portable electronic devices, etc. have a rechargeable battery, that is, a secondary battery. When the charge amount of the battery falls below a predetermined value, it is necessary to charge by a charging device each time. There is. In recent years, charging from a charging device to a portable electronic device is not a contact-type charging method in which charging is performed by connecting a charging terminal in order to prevent contact failure, etc., but contactless power using electromagnetic induction A non-contact charging method in which charging is performed by transmission is employed.

  In the non-contact charging system, the charging device is used together with the charging function for the purpose of preventing heat generation when a metal piece is placed near the charging device, selecting the optimal charging current according to the type of battery, and preventing overcharging. Some devices have a communication function between the portable device and the charged device on the portable electronic device side. Examples of a contact charging system having such a charging function and a communication function are described in Patent Document 1 and Patent Document 2.

  FIG. 9 is a block configuration diagram showing a configuration of a conventional non-contact charging system described in Patent Document 1. In FIG. In FIG. 9, in the charging device 3, when the charged device 4 of the portable terminal containing the IC card is installed in the vicinity thereof, the communication antenna 46 on the charged device 4 side, the communication antenna on the charging device side 35, the IC card reader unit 34 reads the identification information of the IC card unit 45 built in the device to be charged 4, and the control unit 31 checks whether the identification information matches the identification information for which charging is permitted in advance. If determined and coincides, the charging circuit unit 32 is driven to supply power to the power transmission coil 33. In the to-be-charged device 4, the power received by the power receiving coil 41 is smoothed by the smoothing circuit unit 42 and charged to the battery 44 via the charging control circuit unit 43. As described above, in this non-contact charging system, the charging operation can be performed only after the identification information is authenticated on the charging device 3 side. Thus, by performing communication between the charging device and the device to be charged, erroneous charging when a foreign object or the like is placed can be prevented. Further, by storing identification information that can identify the charging method, such as model information and manufacturer information, in the IC card unit 45 that records information, the charging method suitable for each portable terminal is selected and charged. It is also possible to do.

  FIG. 10 is a block configuration diagram showing a configuration of a conventional non-contact charging system described in Patent Document 2. In FIG. In this conventional example, unlike the example of FIG. 9, the power transmission coil 53 and the power reception coil 61 used for charging are also used in communication. That is, in the charging device 5, during the charging operation, the control unit 51 turns on and off the switch 54 in a pulsed manner and repeats this to generate an alternating current in the power transmission coil 53 connected to the charging circuit unit 52. The electric power is induced by electromagnetic induction in the power receiving coil 61 on the charged device 6 side and transmitted. The power received by the power receiving coil 61 is charged to the battery 64 via the smoothing circuit unit 62. On the other hand, when communication is performed, the control unit 51 turns on the switch 54 and performs communication via electromagnetic induction between the power transmission coil 53 and the power reception coil 61. Here, the charging control circuit unit 63 of the device to be charged 6 monitors the charging state of the battery 64. When the battery 64 is fully charged, a signal to that effect is sent from the transmission circuit 65, and the control unit 51 sends the signal to that effect. By receiving and stopping charging, overcharging can be prevented and efficient charging can be performed.

JP 2007-97331 A JP 2001-102974 A

  However, in the prior art of FIG. 9, since the charging device side only reads the identification information of the IC card unit 45, it is possible to identify the product to be charged and to recognize the charging method, but the battery of the charged device is full. The current state of charge, such as whether or not it is charged, cannot be grasped. For this reason, there is a problem that the battery is overcharged or uses transmission power wastefully.

  On the other hand, in the prior art of FIG. 10, the above-mentioned problem can be solved by communicating information on the charging state of the device to be charged. However, a circuit that handles charging power that is 10 times larger than normal communication power is used in communication. Also need to be used. In addition, since the power transmission coil and the power reception coil for charging are commonly used for communication, in order to ensure the performance at the time of communication, the transmission circuit 65 and its peripheral circuits are complicated, and the device cost is increased. There is a problem of becoming higher.

  As described above, in the conventional non-contact charging system that communicates with the device to be charged and can recognize the device to be charged and grasp the charging status of the device to be charged, the circuit for communication becomes complicated, There is a problem of high costs. On the other hand, as a conventional inexpensive method, there is a method of reading only identification information such as an IC card or an IC tag. However, since the charging status cannot be grasped, it is convenient and wastes power and overcharges. There is a problem that there is a risk of becoming.

  Accordingly, an object of the present invention is to provide an inexpensive non-contact charging system capable of recognizing identification information of a charged device and grasping a charging state.

  In order to solve the above problems, the present invention includes a charging device and a charged device, and through electromagnetic induction between a power transmission coil provided in the charging device and a power receiving coil provided in the charged device. In the non-contact charging system that performs non-contact charging from the charging device to the charged device, the charging device includes a charging circuit unit that generates charging power to be supplied to the power transmission coil, and the charged device An information reader unit that reads identification information sent from the information reader unit, a first antenna connected to the information reader unit, and a control unit for controlling the charging circuit unit and the information reader unit. The charging device includes: a battery; a charge control circuit unit that controls charging of the battery; a smoothing circuit unit that smoothes power induced in the power receiving coil and outputs the smoothed power to the charge control circuit unit; An information recording unit including an IC storing therein, a second antenna for performing communication between the information recording unit and the information reader unit, and between the information recording unit and the second antenna The charging control circuit unit monitors a charging state of the battery, and controls the switch when the battery power exceeds a predetermined value to control the information recording unit. When the power of the battery is not more than a predetermined value, the switch is controlled to make the information recording unit and the second antenna conductive. The information reader unit has a function of performing a reading operation of the identification information and outputting the operation result and the identification information to the control unit, the control unit can read the identification information, And before A function of starting the charging operation of the charging circuit unit only when the identification information matches the identification information for which charging is permitted in advance, and a function of stopping the charging operation when the identification information cannot be read. It is characterized by having.

  Here, the device to be charged has a plurality of information recording units each having different information, and the switch conducts between the second antenna and any one of the plurality of information recording units. And a function of non-conducting between the second antenna and all the information recording units, and the charge control circuit unit includes the second antenna according to a state of charge of the battery. And whether the information recording unit selected from the plurality of information recording units is conductive or whether the second antenna and all the information recording units are non-conductive. It may have a function of determining and controlling the switch based on the result.

  Further, the charging device, after starting the charging operation of the charging circuit unit, the charging operation of the charging circuit unit and the reading operation of the identification information of the information reader unit alternately and periodically, The device to be charged may control the switch so as not to conduct everything between the information recording unit and the second antenna while receiving charging power by the charging operation.

  In addition, when the control unit determines a reading operation result and the identification information by an input from the information reader unit, the information reader unit performs the predetermined period of time or a predetermined number of times. The determination may be made after performing the reading operation.

  As described above, in the contactless charging system of the present invention, the charging device has a function of recognizing only identification information such as an inexpensive IC card or IC tag without providing a complicated circuit, and the charged device is in a charged state. Thus, it is determined whether or not an information recording unit such as an IC tag is connected to the second antenna for communication, and it is determined whether or not the identification information can be read on the charging device side. By starting and ending charging according to the determination result, overcharging is prevented, unnecessary power is not transmitted, and power can be reduced. Further, by providing a plurality of information recording units such as IC tags having different information, it is possible to notify a more detailed charging state, and there is an advantage that quick charging and efficient charging are possible.

  As described above, according to the present invention, an inexpensive non-contact charging system capable of recognizing identification information of a charged device and grasping a charging state is obtained.

The block block diagram which shows 1st Embodiment of the non-contact charge system by this invention. The block block diagram which shows 2nd Embodiment of the non-contact charge system by this invention. The flowchart figure which shows the operation | movement flow by the side of the charging device by 1st Embodiment of the non-contact charging system by this invention. The flowchart figure which shows the operation | movement flow by the side of the to-be-charged device by 1st Embodiment of the non-contact charge system by this invention. The flowchart figure which shows the operation | movement flow by the side of the charging device by 2nd Embodiment of the non-contact charging system by this invention. The flowchart figure which shows the operation | movement flow by the side of the to-be-charged apparatus by 2nd Embodiment of the non-contact charge system by this invention. The flowchart figure which shows the operation | movement flow by the side of the charging device by 3rd Embodiment of the non-contact charging system by this invention. The flowchart figure which shows the operation | movement flow by the side of the to-be-charged apparatus by 3rd Embodiment of the non-contact charge system by this invention. The block block diagram which shows the structure of the conventional non-contact charge system. The block block diagram which shows the structure of the conventional non-contact charge system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a first embodiment of a contactless charging system according to the present invention. In FIG. 1, the contactless charging system of the present embodiment includes a charging device 1 and a charged device 2, and includes a power transmission coil 13 provided in the charging device 1 and a receiving coil 21 provided in the charged device 2. This is a non-contact charging system that performs non-contact charging from the charging device 1 to the charged device 2 through electromagnetic induction therebetween. The charging device 1 includes a charging circuit unit 12 that generates charging power to be supplied to the power transmission coil 13, an IC tag reader unit 14 that is an information reader unit that reads identification information transmitted from the charged device 2, and an IC tag reader unit 14. The antenna 15 which is a connected first antenna and the control unit 11 for controlling the charging circuit unit 12 and the IC tag reader unit 14 are provided. The charged device 2 includes a battery 24, a charge control circuit unit 23 that controls charging of the battery 24, a smoothing circuit unit 22 that smoothes the electric power induced in the power receiving coil 21 and outputs the smoothed power to the charge control circuit unit 23. An IC tag unit 25 which is an information recording unit incorporating an IC storing unique identification information, and an antenna 26 which is a second antenna for performing communication between the IC tag unit 25 and the IC tag reader unit 14 And a switch 27 installed between the IC tag unit 25 and the antenna 26. In addition, the charging control circuit unit 23 monitors the charging state of the battery 24. If the power of the battery 24 exceeds a predetermined value, the charging control circuit unit 23 controls the switch 27 to connect the IC tag unit 25 and the antenna 26. When the battery 24 is non-conductive and the power of the battery 24 is equal to or lower than a predetermined value, the switch 27 is controlled so as to make the IC tag portion 25 and the antenna 26 conductive. The IC tag reader unit 14 has a function of reading the identification information and outputting the operation result and the identification information to the control unit 11. The control unit 11 can read the identification information, and the identification information is charged in advance. Has a function of starting the charging operation of the charging circuit unit 12 only when the identification information matches the permitted identification information, and a function of stopping the charging operation when the identification information cannot be read.

  FIG. 3 is a flowchart showing an operation flow on the side of the charging device according to the first embodiment of the non-contact charging system according to the present invention. FIG. 4 is a flowchart showing an operation flow on the charged device side according to the first embodiment of the non-contact charging system according to the present invention. The operation of the contactless charging system according to the first embodiment shown in FIG. 1 will be described below along the flowcharts of FIGS.

  In the initial state, as shown in FIG. 3, the charging device 1 causes the control unit 11 to stop the charging operation of the charging circuit unit 12 and activates only the IC tag reader unit 14 as shown in FIG. The IC tag reader unit 14 emits radio waves through the antenna 15 and waits for a response from an IC tag existing nearby, that is, an IC tag inventory state. On the other hand, as shown in FIG. 4, in the charged device 2, the charge control circuit unit 23 monitors the power state of the battery 24, and when the power of the battery 24 is equal to or lower than a preset threshold value, the switch 27. Is switched to the conductive state (on), and the switch 27 is controlled to the non-conductive state (off) when the set threshold value is exceeded. When the switch 27 is turned on, the antenna 26 is connected to the IC tag portion 25, so that it functions as a normal IC tag, and the identification information (ID) can be read from the IC tag reader portion 14. On the other hand, when the switch 27 is turned off, the IC tag unit 25 and the antenna 26 are disconnected, so that reading from the IC tag reader unit 14 becomes impossible. For example, if the setting threshold value of the battery 24 is 90% of full charge, the switch 27 is turned on when the remaining battery level drops below 90%, and the IC tag reader is turned on when the charged device 2 approaches the charging device 1. The identification information (ID) of the IC tag unit 25 can be read by the unit 14.

  An operation when the power of the battery 24 of the device to be charged 2 is less than the set threshold will be described. As shown in FIG. 4, the switch 27 is turned on and the antenna 26 is connected to the IC tag unit 25. When the charged device 2 approaches the charging device 1 and the IC tag reader unit 14 detects the IC tag unit 25, as shown in FIG. 3, the unique identification information (ID) recorded in the memory of the IC tag unit 25 ), And it is determined whether or not the identification information is identification information that has been permitted to charge in advance, that is, the charging target ID. When the identification information is the charging target ID, the charging circuit unit 12 is activated for charging only. Control to release power. Non-contact charging is performed by electromagnetic induction through the power transmission coil 13 and the power reception coil 21. When charging of the battery 24 is started and the power of the battery 24 exceeds the set threshold value, the charge control circuit unit 23 controls the switch 27 to be turned off. In this case, the IC tag reader unit 14 cannot recognize the identification information, and the control unit 11 controls to stop the charging operation of the charging circuit unit 12 based on the information.

  Therefore, in the non-contact charging system of the present embodiment, it is possible to prevent the battery from being overcharged by being continuously charged even after being fully charged. Further, since the identification information is recognized, it is possible to prevent the metal piece from being exposed to an electromagnetic field for a long time and generating heat. Further, it is possible to prevent erroneous charging of a primary battery that cannot be charged, and sending excessive induced power to an IC card having different identification information. In addition, even if the device to be charged is removed during charging, charging can be stopped immediately, and problems may occur even if foreign objects such as the above-mentioned metal pieces are mistakenly placed after being removed. Absent.

  FIG. 2 is a block diagram showing a second embodiment of the non-contact charging system according to the present invention. The basic configuration of the contactless charging system of the present embodiment is the same as that of the first embodiment of FIG. However, in the present embodiment, charged device 200 has two IC tag units 251 and 252 which are two information recording units having different information, and switch 28 connects antenna 26 with two IC tag units. 251 and 252, a function of disconnecting the antenna 26 from all the IC tag units, and the charge control circuit unit 230 according to the charge state of the battery 24 , Whether to connect the antenna 26 to one IC tag unit selected from the two IC tag units 251 and 252 or to disconnect the antenna 26 from all the IC tag units, and switch based on the result The difference is that it has a function of controlling 28.

  FIG. 5 is a flowchart showing an operation flow on the charging device side according to the second embodiment of the non-contact charging system according to the present invention. FIG. 6 is a flowchart showing an operation flow on the charged device side according to the second embodiment of the non-contact charging system according to the present invention. The operation of the non-contact charging system according to the second embodiment shown in FIG. 2 will be described below along the flowcharts of FIGS.

  The basic operation of the contactless charging system of the present embodiment is the same as that of the contactless charging system of the first embodiment. As shown in FIG. 6, in charged device 200 of the present embodiment, switch 28 is connected to either of two IC tag portions 251 and 252 under the control of charge control circuit 230, or is not connected to either of them. These three states can be switched. The IC tag unit 251 and the IC tag unit 252 have identification information corresponding to the charging status in addition to the identification information specific to the device to be charged as to whether or not charging is performed, and the identification information corresponding to the charging status, that is, charging The situation IDs are set to “1” and “2”, respectively. Switching of the switch 28 is controlled by the power value of the battery 24 detected by the charge control circuit unit 230. Here, if the power value is less than a predetermined setting threshold value 1, it is connected to the IC tag unit 251, and if it is not less than the setting threshold value 1 and not more than the setting threshold value 2 that is larger than the setting threshold value 1, it is connected to the IC tag unit 252. If the threshold value 2 is exceeded, it is off. As shown in FIG. 5, when the charging device 1 cannot detect the identification information as in the first embodiment, the charging circuit unit 12 is stopped to detect the identification information unique to the device to be charged, which is the charging target ID. If so, the charging operation is executed. In this case, in the present embodiment, the charging method can be changed by two charging status IDs. That is, when the charging status ID is “1”, charging is performed by the method of control 1, and when the charging status ID is “2”, charging is performed by the method of control 2. For example, if the control 2 is set to the normal charging mode and the control 1 is set to the rapid charging mode with a large current, the charging state ID = 1 is detected when the charging amount of the battery 24 is extremely small. 12, the quick charge mode of control 1 is set, and the charging time can be shortened. FIG. 2 shows an example in which two IC tag portions are mounted. By further increasing the number of IC tag portions, that is, information recording portions, more detailed battery charging information is notified to the charging device. And more efficient charging is possible.

  Next, a third embodiment of the non-contact charging system according to the present invention will be described. The configuration of the contactless charging system of the present embodiment is the same as that of the first embodiment shown in FIG. However, the operation method in this embodiment is different from that in the first embodiment. In the present embodiment, in FIG. 1, after the charging device 1 starts the charging operation of the charging circuit unit 12, the charging operation of the charging circuit unit 12 and the reading operation of the identification information of the IC tag reader unit 14 are alternately performed. The charged device 2 controls the switch 27 so that the IC tag portion 25 and the antenna 26 are not conductive while receiving the charging power by the charging operation.

  FIG. 7 is a flowchart showing an operation flow on the charging device side according to the third embodiment of the non-contact charging system according to the present invention. FIG. 8 is a flowchart showing an operation flow on the charged device side according to the third embodiment of the non-contact charging system according to the present invention. The operation of the non-contact charging system according to the third embodiment shown in FIG. 1 will be described below along the flowcharts of FIGS.

  In the non-contact charging system of the present embodiment, when the device to be charged 2 approaches the charging device 1 and the IC tag reader unit 14 detects the IC tag unit 25 as shown in FIG. The unique identification information recorded in the information is read, and it is determined whether the identification information is identification information permitted to be charged in advance. If the identification information is permitted, the operation of the IC tag reader unit 14 is stopped, and the antenna 15 Stop sending radio waves. Thereafter, the charging circuit unit 12 is activated and controlled to release charging power. Non-contact charging is performed by electromagnetic induction through the power transmission coil 13 and the power reception coil 21. After the charging operation is performed for a predetermined time set in advance, the operation of the charging circuit unit 12 is once stopped, and the IC tag reader unit 14 is activated again to authenticate the identification information. Thereafter, the same operation is repeated, and when the identification information cannot be authenticated, the charging operation is stopped and the IC tag inventory is entered. On the other hand, as shown in FIG. 8, in the charged device 2, after the charging control circuit unit 23 detects that the charging operation is started when the power of the battery 24 is reduced and the switch 27 is in the standby state. Once the switch 27 is turned off, the charging operation is executed. If the charging from the charging device 1 is interrupted, the switch 27 is turned on again only when the charging is still insufficient and is below the set threshold. When the charging is finally completed and the set threshold value is exceeded, the switch 27 is turned off and the charging device ends the charging operation. This procedure is the same as in FIGS.

  In this embodiment, since communication can be stopped during charging as described above, there is an advantage that wasteful power can be eliminated and low power consumption can be achieved. In addition, when communication and charging are performed at the same frequency, if communication radio waves are transmitted during charging, the charging power may be 10 times or more larger than the communication power, which may result in poor communication. However, in this embodiment, even when the same frequency is used as described above, charging and communication are performed in a time-sharing manner, so that there is an advantage that normal communication can be performed.

  In this embodiment, in order to prevent malfunction, when the control unit 11 determines the result of the read operation and the identification information based on the input from the IC tag reader unit 14, The determination may be made after the IC tag reader unit performs the reading operation a predetermined number of times.

  As described above, in the contactless charging system of the present invention, the information recording unit and the antenna are opened and closed by a switch according to the charging state, and control is performed as to whether or not the identification information is sent to the charging device side. Thus, it is possible to notify the charging status by a simple and economical method, and it is possible to prevent overcharging and erroneous charging.

  In the above embodiment, as the switches 27 and 28, a semiconductor element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) used as a switch in a normal electronic device can be used. As the communication antennas 15 and 26, antenna elements used in ordinary electronic devices and portable electronic devices such as ordinary small dipole antenna elements can be used. In addition, parts and circuits such as a power transmission coil, a power receiving coil, a charging circuit unit, an information reader unit, a control unit, a smoothing circuit unit, and a charging control circuit unit other than a switch are also used without using special components or complicated circuits. It can be realized by using a circuit similar to a general circuit used in the above.

  Needless to say, the present invention is not limited to the above-described embodiment, and the design can be changed according to the purpose and application of the device to which the non-contact charging system is applied. For example, the information recording unit may be an IC tag, an IC card, or an information recording medium having other identification information. The information reader unit may have a function of reading the information stored in the information recording unit via the antenna. The configuration of each circuit unit can also be designed according to the application, and the plurality of circuit units may be separated as in the above embodiment, or may be configured integrally. As the non-contact charging system, other functions such as a display function, an alarm function, and other safety maintenance functions may be added.

1, 3, 5 Charging device 2, 4, 6, 200 Charged device 11, 31, 51 Control unit 12, 32, 52 Charging circuit unit 13, 33, 53 Power transmission coil 21, 41, 61 Power receiving coil 14 IC tag reader unit 15, 26, 35, 46 Antenna 22, 42, 62 Smoothing circuit unit 23, 43, 63, 230 Charge control circuit unit 24, 44, 64: Battery 25, 251, 252 IC tag unit 27, 28, 54 Switch 34 IC Card reader unit 45 IC card unit 65 Transmission circuit

Claims (4)

  A charging device and a to-be-charged device, from the charging device to the to-be-charged device via electromagnetic induction between a power transmission coil provided in the charging device and a power receiving coil provided in the to-be-charged device In the non-contact charging system that performs non-contact charging, the charging device includes a charging circuit unit that generates charging power to be supplied to the power transmission coil, an information reader unit that reads identification information transmitted from the charged device, A first antenna connected to the information reader unit; a control unit for controlling the charging circuit unit and the information reader unit; and the charged device includes a battery and charging the battery. A charge control circuit unit for controlling, a smoothing circuit unit for smoothing the electric power induced in the power receiving coil and outputting the smoothed power to the charge control circuit unit, an information recording unit including an IC storing unique identification information, and A second antenna for performing communication between the information recording unit and the information reader unit; and a switch installed between the information recording unit and the second antenna, and the charging control. The circuit unit monitors the charging state of the battery, and controls the switch to turn off the information recording unit and the second antenna when the battery power exceeds a predetermined value. , When the power of the battery is equal to or less than a predetermined value, the switch is controlled to conduct between the information recording unit and the second antenna, the information reader unit, It has a function of reading the identification information and outputting the operation result and the identification information to the control unit. The control unit can read the identification information, and the identification information is charged in advance. Knowledge A contactless charging system having a function of starting a charging operation of the charging circuit unit only when the information matches the information, and a function of stopping the charging operation when the identification information cannot be read. .   The charged device has a plurality of information recording units each having different information, and the switch has a function of conducting between the second antenna and any one of the plurality of information recording units. And a function of non-conducting between the second antenna and all the information recording units, and the charge control circuit unit is configured to connect the second antenna and the information in accordance with a state of charge of the battery. Determining whether to conduct between one information recording unit selected from a plurality of information recording units, or non-conducting between the second antenna and all information recording units, The contactless charging system according to claim 1, further comprising a function of controlling the switch based on the result.   The charging device, after starting the charging operation of the charging circuit unit, alternately and periodically performs the charging operation of the charging circuit unit and the reading operation of the identification information of the information reader unit, 2. The charging device according to claim 1, wherein while the charging power is received by the charging operation, the switch is controlled so that the information recording unit and the second antenna are all disconnected. Or the non-contact charge system of 2.   When the control unit determines the reading operation result and the identification information by input from the information reader unit, the information reader unit performs the reading operation for a predetermined time or a predetermined number of times. The contactless charging system according to any one of claims 1 to 3, wherein the determination is made after performing the operation.

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