JP2008129919A - Noncontact ic card reader/writer device and control method for output level of transmission radio wave - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncontact IC card reader/writer device capable of properly controlling the output level of a transmission radio wave in accordance with distance to a noncontact IC card. <P>SOLUTION: The noncontact IC card reader/writer device is provided with: a transmitting and receiving means for transmitting a radio wave to the noncontact IC card and receiving a radio wave transmitted from the noncontact IC card; a current level detecting means for detecting the level of current consumption in radio wave transmission by the transmitting and receiving means; an amplitude level detecting means for detecting the amplitude level of the radio wave received by the transmitting and receiving means; and a control means for controlling an output level of the transmission radio wave on the basis of a detection result of the level of current consumption by the current level detecting means and a detection result of the amplitude level by the amplitude level detecting means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention transmits radio waves to a non-contact type IC card, receives radio waves transmitted from the non-contact type IC card, writes data to the non-contact type IC card, The present invention relates to a non-contact type IC card reader / writer device that reads data from a card.

  The present invention also relates to a transmission radio wave output level control method applied to such a non-contact type IC card reader / writer device.

  In recent years, non-contact IC cards that can be used in a non-contact manner have been widely used from the viewpoint of information safety and portability, and radio waves are transmitted to such non-contact IC cards. Various proposals have been made regarding non-contact IC card reader / writer devices that receive radio waves transmitted from contact IC cards, write data to non-contact IC cards, and read data from non-contact IC cards. ing.

  The non-contact type IC card reader / writer device transmits radio waves having a predetermined power to the non-contact type IC card in consideration of various conditions. For example, a non-contact type IC card reader / writer device starts somewhat early in order to communicate with a non-contact type IC card approaching from a distance, or in order to communicate well with a non-contact type IC card that has not been approached. It may transmit strong power radio waves.

  However, such a non-contact type IC card reader / writer device may supply excessive power to a non-contact type IC card that is too close, resulting in destruction of the non-contact type IC card. . Further, when the non-contact type IC card is left for a long time in the state of being close to the non-contact type IC card reader / writer device, there is a problem that the non-contact type IC card abnormally generates heat.

  In order to solve such a problem, a non-contact type IC card reader / writer device having the following configuration has been proposed. A power amplification circuit for amplifying transmission power; a power switching circuit for varying the output level of the power amplification means; an amplitude detection circuit for detecting the amplitude of the received detection signal; and reception detection detected by the amplitude detection circuit. And a non-contact type IC card reader / writer device for switching the output of the power switching circuit based on a determination result of the amplitude determination circuit. Yes.

When the non-contact type IC card comes close to the non-contact type IC card reader / writer device, the voltage value detected by the amplitude detection circuit increases, and the voltage detected by the amplitude detection circuit by the amplitude determination circuit exceeds a predetermined threshold value. If it is determined that the transmission power of the power amplifier circuit is reduced, the power switching circuit reduces the transmission power of the power amplifier circuit. Thus, even when the non-contact type IC card comes close to the non-contact type IC card reader / writer device, the non-contact type IC card can perform normal communication without abnormally generating heat (Patent Document 1). reference).
JP2004-227314

  However, the received signal level detected by the non-contact type IC card reader / writer does not necessarily increase simply because the non-contact type IC card approaches the non-contact type IC card reader / writer. For example, depending on the type of non-contact type IC card, the reception signal level detected by the non-contact type IC card reader / writer gradually increases with the proximity of the non-contact type IC card. The received signal level may once decrease, and the received signal level may increase again when the non-contact type IC card approaches.

  Including such a case, the method of controlling the output level of transmission power based only on the detection result of the received signal level allows accurate control according to the distance between the non-contact type IC card and the non-contact type IC card reader / writer. I can't.

  For example, the non-contact type IC card reader / writer becomes far away from the non-contact type IC card reader / writer as the received signal level decreases even though the non-contact type IC card is close to the non-contact type IC card reader / writer device. May increase the output level of the transmission power and may damage the non-contact IC card.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and is a non-contact type IC card reader capable of appropriately controlling the output level of transmission radio waves according to the distance from the non-contact type IC card. A writer device and a transmission radio wave output level control method are provided.

  The non-contact IC card reader / writer device and the transmission radio wave output level control method of the present invention are configured as follows.

  (1) A non-contact type IC card reader / writer device according to the present invention transmits and receives radio waves to a non-contact type IC card, and receives and transmits radio waves transmitted from the non-contact type IC card; Current level detection means for detecting a current consumption level associated with radio wave transmission by the means, amplitude level detection means for detecting the amplitude level of the radio wave received by the transmission / reception means, and detection result of the current consumption level by the current level detection means And control means for controlling the output level of the transmission radio wave based on the detection result of the amplitude level by the amplitude level detection means.

  (2) The transmission radio wave output level control method of the present invention transmits a radio wave to a non-contact type IC card, detects a current consumption level associated with the radio wave transmission, and transmits from the non-contact type IC card. While receiving the radio wave, the amplitude level of the received radio wave is detected, and the output level of the transmission radio wave is controlled based on the detection result of the consumption current level and the detection result of the amplitude level.

  According to the present invention, it is possible to provide a non-contact type IC card reader / writer device and a transmission radio wave output level control method capable of appropriately controlling the output level of a transmission radio wave according to the distance from the non-contact type IC card.

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

  The present invention uses electromagnetic coupling to communicate between a non-contact type IC card reader / writer device and a non-contact type IC card, and to supply power from the non-contact type IC card reader / writer device to the non-contact type IC card. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact IC card system to be performed. .

  FIG. 1 shows a schematic configuration of a non-contact type IC card reader / writer device 101 according to an embodiment of the present invention, and a schematic configuration of a non-contact type IC card 120 that communicates with the non-contact type IC card reader / writer device 101. FIG.

  As shown in FIG. 1, a non-contact IC card reader / writer device 101 includes a control circuit 102, a modulation circuit 103, an amplification circuit 104, a loop antenna 105, a detection circuit 106, a reception circuit 107, an amplitude detection circuit 108, and a determination circuit 109. , A power switching circuit 110, and a current detection circuit 111.

  The control circuit 102 includes a memory, a CPU, and the like, and stores data and processes data. The modulation circuit 103 modulates the carrier with the data output from the control circuit 102. The amplifier circuit 104 amplifies the output of the modulation circuit 103 to a specified transmission power. The loop antenna 105 radiates a carrier output from the amplifier circuit 104 to supply power to the contactless IC card 120 and transmit data, and a carrier that is AM-modulated with data by a load modulation method is contactless. Received from the IC card 120.

  The detection circuit 106 is configured by a diode bridge or the like, and demodulates data from the carrier received by the loop antenna 105. The reception circuit 107 amplifies the data demodulated by the detection circuit 106, shapes the waveform, and transmits the waveform to the control circuit 102. The amplitude detection circuit 108 rectifies the detection output of the detection circuit 106 and converts it into a DC voltage. The determination circuit 109 compares the output of the amplitude detection circuit 108 with a predetermined threshold value and makes a size determination. The power switching circuit 110 switches the transmission power of the amplifier circuit 104 in two stages according to the output of the comparison circuit 109. The current detection circuit 111 converts the current consumption value of the transmission circuit system including the modulation circuit 103, the amplification circuit 104, and the loop antenna 105 into a DC voltage.

  One non-contact type IC card 120 includes a loop antenna 121 and a control circuit 122.

  The loop antenna 121 receives the carrier radiated from the loop antenna 105 of the non-contact type IC card reader / writer device 101 and supplies the carrier to the control circuit 122, and also AM modulates the data supplied from the control circuit 122 by the load modulation method. Radiated carriers. The control circuit 122 includes a memory, a CPU, and the like. The control circuit 122 rectifies the carrier supplied from the loop antenna 121 as an operation power supply, and stores data and processes data.

  Next, the operation of the non-contact IC card reader / writer device 101 described above will be described.

  The non-contact type IC card reader / writer device 101 always outputs the carrier generated by the modulation circuit 103 and amplified by the amplification circuit 104 from the loop antenna 105. When the non-contact type IC card 120 comes close to the non-contact type IC card reader / writer device 101, the antenna 121 receives a carrier and rectifies the received wave to obtain an operating power source.

  Further, the non-contact type IC card reader / writer device 101 sends a command from the control circuit 102, applies AM modulation to the carrier through the modulation circuit 103, and sends the command at a constant cycle. The non-contact type IC card 120 obtains an operation power from the carrier, receives a command sent from the non-contact type IC card reader / writer device 101 at a constant period, generates a response to the command by the control circuit 122, The carrier is AM-modulated by a load modulation method that changes the load of the antenna 121 and responds to the non-contact type IC card reader / writer device 101. In the non-contact type IC card reader / writer device 101, the AM modulated wave returned by the load modulation method is received by the loop antenna 105, demodulated by the detection circuit 106, the response is recognized by the control circuit 102, and data transfer is completed. .

  For example, the transmission power of the non-contact type IC card reader / writer device 101 is set to about 1 W so that communication can be performed even when the non-contact type IC card 120 is separated by about 10 cm. However, when the non-contact type IC card 120 approaches the loop antenna 105 of the non-contact type IC card reader / writer device 101 in this output state (for example, the non-contact type IC card 120 becomes a loop of the non-contact type IC card reader / writer device 101). When it is close to the antenna 105 within several centimeters), the received power of the non-contact type IC card 120 becomes too large. For this reason, the non-contact type IC card 120 cannot consume the received power, and the non-contact type IC card 120 may be heated and destroyed.

  A transmission radio wave output level control method 1 and a transmission radio wave output level control method 2 for solving this problem will be described below.

・ Transmission radio wave output level control method 1
When the non-contact type IC card 120 is close to the loop antenna 105 of the non-contact type IC card reader / writer device 101, the detection circuit 106 detects that the reception detection level simply increases as shown in FIG. At the same time, the amplitude detection circuit 108 detects an increase in the detection voltage. Then, the determination circuit 109 determines that the detection voltage of the amplitude detection circuit 108 has exceeded a predetermined threshold value. That is, the determination circuit 109 determines that the non-contact type IC card 120 has approached. Based on this determination, the power switching circuit 110 reduces the transmission power to a specified level. As a result, even when the non-contact type IC card 120 is close to the non-contact type IC card reader / writer device 101 more than necessary, the non-contact type IC card 120 can communicate normally without being heated more than necessary. Can be done.

  The non-contact type IC card reader / writer device 101 constantly monitors the reception detection level. When the non-contact type IC card 120 is moved away again, the amplitude detection circuit 108 and the determination circuit 109 have a low reception detection level. Detect that. Based on this detection, the power switching circuit 110 increases the transmission power to a level of about 1 W.

  However, among non-contact type IC cards that have been widely spread in recent years, not only those in which the received signal level simply increases as the reader / writer approaches, but also those in which the level decreases and increases again at an intermediate position as shown in FIG. Exists. For this reason, it may not be possible to accurately determine whether or not the non-contact type IC card is approaching only by detecting the reception signal level described above. That is, the transmission radio wave output level control method 1 described above may not be able to perform appropriate transmission radio wave output level control.

  Therefore, the transmission radio wave output level control method 2 capable of appropriate transmission radio wave output level control even when the reception signal level does not simply increase as described above will be described.

・ Transmission radio wave output level control method 2
The non-contact type IC card reader / writer device 101 has a characteristic that the current value consumed by the transmission circuit decreases as the non-contact type IC card 120 approaches. The transmission radio wave output level control method 2 uses this characteristic to accurately detect the approaching state of the non-contact type IC card 120. For example, as shown in FIG. 4, when the non-contact type IC card reader / writer device 101 has a characteristic that current consumption is minimized when the non-contact type IC card 120 comes closest, the current detection circuit 111. When the detection value of the current detection circuit 111 is small, it can be seen that the non-contact type IC card 120 is approaching the non-contact type IC card reader / writer device 101, and the detection value of the current detection circuit 111 is large. It can be seen that the non-contact type IC card 120 is away from the non-contact type IC card reader / writer device 101.

  The non-contact type IC card reader / writer device 101 detects whether the received signal level is higher than the threshold value or lower than the threshold value, and further detects an increasing tendency or a decreasing tendency of the current consumption value (by a combination of both detections). It is accurately determined whether the non-contact type IC card 120 is approaching or moving away. As a result, it is possible to switch the transmission power to a low value at a position where the non-contact type IC card 120 approaches to some extent, and to switch the transmission power to a high value when the non-contact type IC card 120 moves away. As a result, it is possible to supply necessary and sufficient power from the non-contact type IC card reader / writer device 101 to the non-contact type IC card 120 and to avoid excessive heat generation of the non-contact type IC card 120 and circuit breakage associated therewith. It becomes possible.

  The non-contact type IC card reader / writer device 101 normally operates with a sufficiently high transmission power of about 1 W. When the non-contact type IC card 120 approaches the loop antenna 105 of the non-contact type IC card reader / writer device 101, the non-contact type IC card reader / writer device 101 decreases the transmission power level. Thereby, it is possible to prevent the non-contact type IC card 120 from being abnormally heated and destroyed, and it becomes possible to use the non-contact type IC card 120 with peace of mind, and the usability is greatly improved.

  Next, the transmission radio wave output level control method 2 will be described. FIG. 5 is a flowchart showing an example of the transmission radio wave output level control method 2.

  First, the non-contact type IC card reader / writer device 101 sets the transmission output to the high mode (first output level) (ST101), and then transmits a command to the non-contact type IC card 120 (ST102). The non-contact type IC card reader / writer device 101 enters a reception mode after command transmission and waits for reception of a signal from the non-contact type IC card 120. When the non-contact type IC card reader / writer device 101 receives a signal from the non-contact type IC card 120 (ST103), the current value (value converted to voltage) monitored by the current detection circuit 111 is the value of the control circuit 102. It is held in a memory or the like (ST104). Here, the stored current value is defined as a current value A. The amplitude detection circuit 108 continues to detect the amplitude of the reception level (ST105), and the current detection circuit 111 continues to detect the current value (ST106). A current value detected by the current detection circuit 111 is defined as a current value B.

  When the reception level by the amplitude detection circuit 108 becomes higher than a preset threshold value (ST107, YES), the current value A is compared with the current value B by the control circuit 102, and the current value B is smaller than the current value A (ST108, YES), the control circuit 102 determines that the non-contact type IC card 120 is approaching (ST109), and changes the transmission output from the high mode (first output level) to the low mode (second output level lower than the first output level). (ST110). If the mode has already been switched to the low mode, it is left as it is (ST110).

  If the current value B is equal to or greater than the current value A (ST108, NO), the control circuit 102 determines that the non-contact IC card 120 is moving away (ST116), but sets the transmission output to the high mode (first output level). ) To the low mode (second output level) (ST117). If the mode has already been switched to the low mode, it is left as it is (ST110).

  When the reception level by the amplitude detection circuit 108 is equal to or lower than a preset threshold value (ST107, NO), the control circuit 102 compares the current value A with the current value B, and the current value B is smaller than the current value A (ST113, YES). The control circuit 102 determines that the non-contact type IC card 120 is approaching (ST114), and switches the transmission output from the low mode (second output level) to the high mode (first output level) (ST115). If the mode has already been switched to the high mode, it is left as it is (ST115).

  When the current value B is equal to or greater than the current value A (ST113, NO), the control circuit 102 determines that the non-contact IC card 120 is moving away (ST112), and sets the transmission output to the low mode (second output level). To high mode (first output level) (ST111). If the mode has already been switched to the high mode, it is left as it is (ST111).

  Among non-contact type IC cards that have become popular in recent years, there are not only those in which the received signal level simply increases as the reader / writer approaches, but also those in which the level decreases at an intermediate position and increases again as shown in FIG. To do. In such a case, only the detection of the reception signal level, that is, the transmission radio wave output level control method 1 may not perform appropriate transmission radio wave output level control.

  However, in the transmission radio wave output level control method 2 as described above, in addition to the detection of the received signal level in the non-contact type IC card reader / writer device 101, these are detected by detecting the current value consumed in the transmission circuit unit. By combining the results, it is possible to accurately determine whether the non-contact type IC card 120 is approaching or moving away from the loop antenna 105 of the non-contact type IC card reader / writer device 101 even when the received signal level does not simply increase. . As a result, the transmission power can be appropriately switched to a low value at a position where the non-contact type IC card 120 is approached to some extent, and the transmission power can be appropriately switched to a high value when moving away from the non-contact type IC card reader. Necessary and sufficient power is supplied from the writer device 101 to the non-contact type IC card 120, and it is possible to avoid excessive heat generation of the non-contact type IC card 120 and circuit damage associated therewith. In addition, when the non-contact type IC card 120 is overpowered and generates heat in the vicinity of the loop antenna 105, it is possible to avoid a problem that a response is not returned and as a result communication is disabled.

  In the above description, the non-contact IC card reader / writer device 101 has been described as having a characteristic that the current value consumed by the transmission circuit decreases as the non-contact IC card 120 approaches. However, the present embodiment is not limited to this. For example, when the non-contact type IC card reader / writer device 101 has a characteristic that the current value consumed by the transmission circuit increases as the non-contact type IC card 120 approaches, the following control is performed.

  When the reception level by the amplitude detection circuit 108 is higher than a preset threshold value and the current value A and the current value B are compared by the control circuit 102 and the current value B is smaller than the current value A, the control circuit 102 It is determined that the IC card 120 is moving away, and the transmission output is switched from the high mode to the low mode. If it has already been switched to low mode, leave it as it is. When the current value B is equal to or greater than the current value A, the control circuit 102 determines that the non-contact IC card 120 is approaching and switches the transmission output from the high mode to the low mode. If it has already been switched to low mode, leave it as it is.

  When the reception level by the amplitude detection circuit 108 is equal to or lower than a preset threshold value and the current value A is compared with the current value B by the control circuit 102 and the current value B is smaller than the current value A, the control circuit 102 It is determined that the card 120 is moving away, and the transmission output is switched from the low mode to the high mode. If it has already been switched to high mode, leave it as it is. When the current value B is equal to or greater than the current value A, the control circuit 102 determines that the non-contact type IC card 120 is approaching and switches the transmission output from the low mode to the high mode. If it has already been switched to high mode, leave it as it is.

  The transmission radio wave output level control method 1 and the transmission radio wave output level control method 2 can be realized by the non-contact IC card reader / writer device 101 shown in FIG. 1, but the transmission radio wave output level control method 1 is shown in FIG. The non-contact type IC card reader / writer device 101 shown in FIG.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. In addition, the embodiments may be appropriately combined as much as possible, and in that case, the combined effect can be obtained. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.

1 is a diagram showing a schematic configuration of a non-contact type IC card reader / writer device according to an embodiment of the present invention and a schematic configuration of a non-contact type IC card that communicates with the non-contact type IC card reader / writer device. An example in which the reception detection level on the contactless IC card reader / writer device side simply increases when the contactless IC card comes close to the loop antenna of the contactless IC card reader / writer device, that is, the contactless IC card reader / writer device side. It is a figure which shows the 1st example of the received signal level characteristic which changes according to the distance with an IC card reader / writer apparatus. When the non-contact IC card is close to the loop antenna of the non-contact IC card reader / writer device, the reception detection level on the non-contact IC card reader / writer device side does not simply increase, and reception detection is performed at an intermediate position. It is a figure which shows the 2nd example of the received signal level characteristic which changes according to the example of a level falling and increasing again, ie, the distance of an IC card and a non-contact-type IC card reader / writer apparatus. An example in which current consumption is minimized when a non-contact type IC card comes closest to the non-contact type IC card reader / writer device, that is, consumption that varies depending on the distance between the IC card and the non-contact type IC card reader / writer device. It is a figure which shows the example of an electric current characteristic. It is a flowchart which shows an example of the transmission radio wave output level control method 2 (The output level control of the transmission radio wave based on the comparison result of an amplitude level and a threshold value, and the increase / decrease tendency of a consumption current level). It is a figure which shows an example of schematic structure of the non-contact-type IC card reader / writer apparatus which can implement | achieve only the transmission radio wave output level control method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Non-contact IC card reader / writer apparatus, 102 ... Control circuit, 103 ... Modulation circuit, 104 ... Amplifier circuit, 105 ... Loop antenna, 106 ... Detection circuit, 107 ... Reception circuit, 108 ... Amplitude detection circuit, 109 ... Determination Circuit 110 110 Power switching circuit 111 Current detection circuit 120 Non-contact IC card 121 Loop antenna 122 Control circuit

Claims (7)

Transmitting and receiving means for transmitting radio waves to the non-contact type IC card and receiving radio waves transmitted from the non-contact type IC card;
Current level detection means for detecting a current consumption level associated with radio wave transmission by the transmission / reception means;
Amplitude level detecting means for detecting the amplitude level of the radio wave received by the transmitting / receiving means;
Control means for controlling the output level of the transmission radio wave based on the detection result of the consumption current level by the current level detection means and the detection result of the amplitude level by the amplitude level detection means;
A non-contact type IC card reader / writer device comprising:   The control means determines the output level of the transmission radio wave based on a combination of a comparison result between the amplitude level detected by the amplitude level detection means and a threshold value, and a trend of increase / decrease in the consumption current level detected by the current level detection means. The non-contact type IC card reader / writer device according to claim 1, wherein the non-contact type IC card reader / writer device is controlled.   2. The non-contact type IC card reader / writer device according to claim 1, wherein the current consumption level decreases as the non-contact type IC card approaches. The control means includes
In the initial stage, the transmission of the transmission wave of the first output level is controlled,
In a stage where the amplitude level detected by the amplitude level detection means is compared with a threshold value and the amplitude level is higher than the threshold value and the current consumption level detected by the current level detection means is declining. Controlling transmission of a transmission wave having a second output level lower than the first output level;
In a stage where the amplitude level detected by the amplitude level detection means is compared with a threshold value, and it is determined that the amplitude level is higher than the threshold value and the current consumption level detected by the current level detection means tends to increase. Control the transmission of the transmission wave of the second output level,
In a stage where the amplitude level detected by the amplitude level detection means is compared with a threshold value, and it is determined that the amplitude level is equal to or less than the threshold value and the current consumption level detected by the current level detection means tends to decrease. Control the transmission of the first output level transmission radio wave,
In a stage where the amplitude level detected by the amplitude level detection means is compared with a threshold value and the amplitude level is equal to or less than the threshold value and the current consumption level detected by the current level detection means tends to increase. Control transmission of the first output level transmission radio wave,
The non-contact type IC card reader / writer device according to claim 3. While transmitting radio waves to the non-contact IC card, it detects the current consumption level associated with this radio transmission,
While receiving the radio wave transmitted from the non-contact IC card, detecting the amplitude level of the received radio wave,
Based on the detection result of the consumption current level and the detection result of the amplitude level, the output level of the transmission radio wave is controlled.
A transmission radio wave output level control method.   6. The transmission radio wave output according to claim 5, wherein an output level of the transmission radio wave is controlled based on a combination of a comparison result between the detected amplitude level and a threshold value and an increase / decrease tendency of the detected current consumption level. Level control method. A transmission radio wave output level control method applicable to a non-contact type IC card reader / writer having a characteristic that a consumption current level decreases as the non-contact type IC card approaches,
In the initial stage, the transmission of the transmission wave of the first output level is controlled,
A second output level that is lower than the first output level when the detected amplitude level is compared with a threshold and it is determined that the amplitude level is higher than the threshold and the detected current consumption level tends to decrease. To control the transmission of
When the detected amplitude level is compared with a threshold and it is determined that the detected amplitude level is higher than the threshold and the detected current consumption level tends to increase, transmission of the transmission radio wave at the second output level is performed. Control
When the detected amplitude level is compared with a threshold and it is determined that the detected amplitude level is equal to or less than the threshold and the detected current consumption level is decreasing, transmission of the transmission wave of the first output level is performed. Control
When the detected amplitude level is compared with a threshold value and it is determined that the amplitude level is equal to or lower than the threshold value and the detected current consumption level tends to increase, transmission of the transmission wave of the first output level is performed. Control,
The transmission radio wave output level control method according to claim 5.

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