JPH11102480A - Gas supply controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a device and to improve security capability. SOLUTION: When an IC card 40 is inserted (S27:YES), error history is displayed on a display part 32 (S29). When the IC card 40 is pulled out (S30:NO), 'CL' is flickered on the display part 32 for five seconds (S31), and the deletion possible state of error history is informed. When the IC card 40 is not inserted again during five minutes (S32:NO, S33:YES), control is terminated (S17). When the IC card 40 is inserted during five minutes (S32:YES), stored error history is deleted (S34), and control is terminated (S17).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a gas supply control device that enables gas to be used based on data stored in a prepaid card.

[0002]

2. Description of the Related Art Conventionally, a prepaid gas supply control device has been considered in which a prepaid card storing balance data corresponding to a prepaid amount is inserted so that gas can be supplied based on the balance data. ing. This gas supply control device subtracts balance data stored in a prepaid card based on the amount of gas used, and when the balance becomes 0, shuts off gas supply and makes gas unusable. is there. By installing such a gas supply control device in each home, it is possible to reliably collect gas charges in advance and to reduce labor costs for gas meter reading and charge collection.

[0003]

In order to realize such a system, it is necessary to make the apparatus itself as inexpensive as possible in order to install the apparatus in each home. High security to prevent use is required. On the other hand, such a device has a gas supply control function normally required by a general user,
An additional function, such as displaying an error history, required by the administrator during maintenance or the like is naturally required. However, providing an operation switch for switching between the normal mode and the additional function mode increases the cost of the apparatus. There was such a problem. In addition, it is not preferable that such an operation switch is provided in the apparatus, because even a function used only by the administrator can be easily operated by a general user. An object of the present invention is to solve the above-mentioned problems, to reduce the cost of the device, and to enhance the security.

[0004]

According to a first aspect of the present invention, there is provided a gas supply control device for reading a balance data from a prepaid card storing balance data corresponding to a prepaid amount. In the gas supply control device which can supply the fuel gas based on the above, the operation of the designated mode is performed by inserting a special card for maintenance etc. different from the above-mentioned prepaid card, and the operation from the state is started. The gist is to shift to another mode based on the timing of inserting and removing a special card.

According to a second aspect of the present invention, there is provided a gas supply control device according to the first aspect of the present invention, wherein a memory for storing various information data and a display device capable of displaying the information data are provided. A display unit for switching between a data display mode for displaying the information data on the display unit and a data erasing mode for erasing the information data stored in the memory at the timing of inserting and removing the special card. .

According to a third aspect of the present invention, there is provided a gas supply control device according to the second aspect, wherein the special card is removed within a predetermined time after the special card is removed during the data display mode. The gist is that the mode is switched to the data erasing mode by being reinserted.

[0007] The gas supply control device according to the first aspect of the present invention having the above configuration reads balance data corresponding to a prepaid amount from a prepaid card and enables supply of fuel gas based on the balance data. Also, the operation of the designated mode is performed by inserting a special card for maintenance or the like different from the prepaid card, and the mode is shifted to another mode based on the timing of removing and inserting the special card from that state. Therefore, there is no need to provide an operation switch or the like for mode switching.

Further, the present invention has the above-mentioned structure.
The gas supply control device described includes a memory for storing various information data, and a display unit capable of displaying the information data. Then, the mode is switched between a data display mode for displaying information data on the display unit and a data erasing mode for erasing information data stored in the memory according to the timing of inserting and removing the special card. Therefore, if the error history or the like is stored in the memory as information data, for example, the error history can be displayed at the time of maintenance, and the unnecessary information data can be erased from the memory.

Further, the present invention has the above-mentioned structure.
The gas supply control device described above switches to the data erasing mode when the special card is removed during the data display mode and then reinserted within a predetermined time. Therefore, the mode can be switched by a simple card insertion / removal operation.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the water heater of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a water heater as an embodiment of the present invention that realizes a prepaid system for a usage fee. The water heater 10 includes a heat exchanger 13 in which a water supply channel 11 and a hot water channel 12 are connected, and a heat exchanger 13.
A burner 14 for heating water flowing through the hot water supply unit and a hot water supply control unit 15 for controlling combustion. The water supply path 11 is provided with a flow rate sensor 16 for detecting the flow rate of incoming water and an incoming water temperature sensor 17 for detecting the incoming water temperature, and the tapping water path 12 is provided with a tapping temperature sensor 18 for detecting the tapping temperature. A gas supply path 19 for supplying gas to the burner 14 includes a main solenoid valve 20 for opening and closing the flow path, a main solenoid valve 21, and a proportional valve for adjusting a gas supply amount by changing an opening degree in accordance with an amount of electricity. 22 are provided.

The hot water supply control unit 15 includes a CPU, a RAM, and a ROM, which constitute a well-known arithmetic and logic operation circuit (not shown), an input interface for inputting signals from various sensors, and
It is composed of an output interface that outputs drive signals to various actuators. Then, in order to bring the tapping temperature close to the set temperature (fixed at 60 ° C. in this embodiment), 200 ms
The outflow water temperature, the inflow water temperature, and the outflow water temperature are detected for each ec, and the outflow water temperature control such as controlling the burner combustion amount based on the detected values is performed. That is, the amount of heat for heating the detected incoming water flow rate and incoming water temperature to the set temperature is calculated (so-called feed forward calculation), and the feed forward calculated value is corrected based on the deviation between the outlet water temperature and the set temperature (so-called feed forward calculation). (Feedback calculation) The required amount of heat is determined, and the proportional valve 22 is controlled to an opening degree such that the required amount of heat can be obtained.

A card device 30 is connected to the water heater 10. The water heater 10 and the card device 30 are connected via a communication cable, and the card device 30 can be installed indoors even with the outdoor water heater 10. The card device 30 includes a read / write unit 31 for reading and rewriting data stored in the IC card 40, a display unit 32 for displaying the balance frequency, and a card control unit 33 for controlling these.

The IC card 40 has a built-in EEPROM (non-volatile memory) for storing a plurality of data, and has a terminal 41 for electrically connecting to the read / write section 31 on the card surface. In the EEPROM, balance data indicating a prepaid amount is stored in units of 10 yen. In addition, as an owner data for specifying a card holder, an area code for identifying an area of use, and for identifying a supplier. , A manager code for identifying a manager, a resident code indicating a room number, and the like. Also stored are unit price data indicating the unit price of the usage fee, a system code indicating the type of card, and the like.

The read / write unit 31 reads and rewrites data while holding the IC card 40 inserted manually at a fixed position. Therefore, unlike a magnetic card reading device, components such as a card transport motor and a magnetic head are not required, and a compact configuration can be achieved.

The display unit 32 is composed of a two-digit seven-segment LED, and displays the balance stored in the IC card 40 as a two-digit number with 100 yen as one frequency. If the balance is 10
When the balance is less than 0 yen, “0” is displayed blinking to notify that the balance is running low, and when the balance is 0 yen, “0” is lit.

When the IC card 40 is inserted, the card control section 33 reads a plurality of data stored by the read / write section 31. The card control unit 33 has an EEPROM for storing data, stores the owner data of the IC card 40 inserted for the first time as card information, and as shown in FIG.
The owner data of the C card 40 is collated with the already stored card information every time, and when all codes match, the IC card 40 can be used, and the balance frequency is displayed on the display unit 32. By such a check, the devices that can be used for each IC card 40 are limited to prevent unauthorized use. In addition, the card control unit 33 includes the hot water supply control unit 1.
When the IC card 40 has a balance, an operation permission signal for permitting the operation of the water heater 10 is transmitted to the hot water controller 15.

The hot water supply control unit 15 is in the operable state only when the operation permission signal is received from the card control unit 33. In this state, the hot water supply curl (not shown) is opened and a predetermined operation start flow rate Qs is exceeded. When the incoming water flow is detected,
The main solenoid valve 20 and the original solenoid valve 21 are opened and the burner 14
And an ignition control such as ignition by an ignition device (not shown). While the burner 14 is burning, the hot water temperature is brought close to the set temperature by hot water temperature control, and an in-combustion signal for notifying that the combustion operation is being performed is transmitted to the card control unit 33. Thereafter, when the flow rate of the incoming water decreases below the operation stop flow rate Qe, the main solenoid valve 2
0. Fire extinguishing control such as closing the original electromagnetic valve 21 to shut off gas supply and extinguish the burner 14 is performed.

The hot water supply control unit 15 calculates a usage fee based on the amount of heat consumed by the burner 14. This charge is the maximum combustion amount of the burner 14 (30000 kcal / h in this embodiment).
Is calculated based on the unit price of the usage fee (100 yen in the present embodiment) when the device is used for a predetermined time (15 minutes in the present embodiment) for a given amount of heat. The amount of heat when used at a burning amount of 30,000 kcal / h for 15 minutes is 30,000 kcal / h × 15/60 = 7,500 kcal, so that control is performed so that 7,500 kcal can be consumed for 100 yen. In the present embodiment, the balance stored in the card control unit 33 is subtracted by 1/100 (one yen) of the unit price by transmitting a subtraction command signal to the card control unit 33. Is possible. The balance of the IC card 40 is rewritten every time the subtracted value reaches 10 yen.

The amount of heat of the burner 14 is determined by calculating the amount of heat to be consumed from the required amount of heat obtained every 200 msec by controlling the hot water temperature, and integrating this value. For example, when the required heat is 30,000 kcal / h, 200 ms
The amount of heat consumed per ec is 30,000 kcal / h × 0.2 / 3600 = 1.67 kcal. The calorie calculated in this way is integrated, and every time the accumulated calorie reaches 75 kcal, a subtraction command signal is transmitted to the card control unit 33 to reduce the balance by one yen, thereby enabling the calorie consumption of 75 kcal again. Therefore, the usable time per unit price becomes longer as the fuel is used with a smaller combustion amount. Note that the card device 30 is provided in the water heater 10 so as to be detachable, and the hot water controller 15 controls the same as a normal water heater when the card device 30 has never been connected. However, once the card device 30 is connected, the hot water supply control unit 15 stores the data, and the card control unit 3 of the card device 30
3 is a card-only machine that can perform a hot-water supply operation only in a state in which the operation permission signal is received from 3. Therefore, a common water heater can be used in the normal usage mode and the usage mode in which the usage fee is paid by the card, and the unauthorized use in which the card device 30 is used without being connected in the usage mode in which the usage fee is paid by the card. Use can be prevented.

The card control section 33 is provided with the inserted IC.
By storing the balance of the card 40, the IC card 40 fails and data cannot be read, or the IC card 40
If you lose your balance, you can check the balance. Here, when the same user owns a plurality of cards, the balance is different even if the owner data is the same. Therefore, a card No. for identifying a plurality of cards having the same owner data is used. Write. That is, when the owner data of the inserted IC card 40 matches the card information, the card No. stored in the card is stored. And check the card No. Is stored, the card No. is stored. Is written in the storage area corresponding to the card No. Is not stored, an unused card No. is stored. Is newly written to the IC card 40. As described above, the card Nos. 1 to 9 are provided for each card. And the balance stored in each card is assigned to the card No.
, It is possible to store the balance of up to nine cards. By storing the balance in this way, the balance stored in the card control unit 33 can be read and the balance can be refunded when the IC card 40 fails or is lost.

For example, the burner 1 in the water heater 10
In the case where an abnormality such as the disappearance of 4 or hot water has occurred, an error code corresponding to the content of the abnormality is displayed on the display unit 32. Then, the card control unit 33 stores the contents of the abnormality that has occurred in the past as an error history so that the cause of the abnormality can be grasped during maintenance.

When reading out the balance and error history stored in the card control unit 33, a special card having a special function is used. This special card is owned by the manager and is distinguished from the general card owned by the resident by the contents of the system code stored in the card, and the special card is further classified into a maintenance card and a clear card by the contents of the resident code. You. Unlike a general card, this dedicated card is usable if all codes other than the resident code match by comparing the owner data with the card information. As described above, since it can be used even if the resident codes do not match, it can be used in all water heaters owned by the residents under the jurisdiction of the manager.

The maintenance card, which has a resident code of "001" among the special cards, is used for operation at the time of maintenance and for displaying and deleting an error history. The maintenance card stores remaining time data in the balance data storage area of the general card, and makes the water heater 10 operable based on the remaining time data. The reason for limiting the time based on the time is that the maintenance card can be used in a wider range than the general card, so that it is considered that the maintenance card is likely to be fraudulent. Therefore, the maximum value of the remaining time data is set to a short time (for example, 10 minutes) at which the maintenance work can be performed, and illegal use is prevented by preventing a large amount of gas from being used. If the maintenance card is inserted again within 5 seconds after the removal of the maintenance card, an error history display mode is set, and error codes for the past eight times are sequentially displayed. Further, if the maintenance card is inserted again within 5 seconds after the removal of the maintenance card in the error history display mode, the stored error history is deleted.

The clear card is a special card whose resident code is "002" and is used when displaying and deleting the stored balance. When the clear card is inserted, the card No. The display mode of the balance stored for each card is displayed, and the card No. The balance is displayed for each order. If the clear card is inserted again within 5 seconds after the removal of the clear card, the stored balance and the resident code of the card information are deleted. By erasing the balance and the resident code in this way, the resident code can be changed when the resident moves or when the balance is refunded, and the card used up to that point can no longer be used. Can be prevented.

Next, control processing performed by the card control unit 33 will be described with reference to the flowchart of FIG. This routine starts when the IC card 40 is inserted. First, it is determined from the system code stored in the inserted IC card 40 whether it is a general card or a special card. If the card is a general card (S1: general), the stored card information is collated with the owner data of the inserted IC card 40. If the IC card 40 has been inserted at least once in the past, since the card information is stored (S2: YES), it is checked against the owner data of the inserted IC card 40, and all codes match. (S5: YES), the card can be used. However, when the resident code is erased by the clear card, the resident code is not stored in the card information (S2: NO, S3: YES). If all codes other than the code match (S6: YES), the resident code of the IC card 40 is newly stored in the card information (S7). On the other hand, when the IC card 40 is inserted for the first time, the card information is not stored (S2: N
O, S3: NO), the owner data stored in the inserted IC card 40 is stored as card information (S).
4).

Next, the card No. is inserted into the inserted IC card 40. Is checked to see if the card number is stored. Is not stored (S8: NO), it is determined that the card is a new card, and the currently used card No. is used. Is written (S9). Then, the balance stored in the card is assigned to the card No. (S10).

Next, the balance frequency is displayed on the display unit 32 (S
11) While there is a balance (S12: YES), an operation permission signal is transmitted to the hot water supply control unit 15 (S13) to enable the hot water supply operation. Thereafter, when a subtraction command signal is received from the hot water supply control unit 15 (S14: YES), one yen is subtracted from the balance (S15). Thereafter, when the card is removed (S16: NO), the control ends (S17).

On the other hand, in step 1, the inserted I
If it is determined that the C card 40 is a special card (S1: special), the stored card information and the owner data of the special card are collated, and if all except the resident code match (S19). : YES) Make the card usable. However, if the card information is not stored (S18: NO), the card can be used without collation. Next, it is determined from the resident code whether the IC card 40 is a maintenance card or a clear card. When the resident code is “001” (S20: 001)
It is determined that the card is a maintenance card, and while there is remaining time (S21: YES), an operation permission signal is transmitted to the hot water supply control unit 15 (S22) to enable the hot water supply operation. While the in-combustion signal is being received from the hot water supply control unit 15 (S2
3: YES), the remaining time is subtracted based on the time measured by the timer (S24). Thereafter, when the IC card 40 is removed (S25: NO), "E" is blinked on the display unit 32 for 5 seconds (S26) to notify that the error history can be displayed. If the IC card 40 has not been inserted during these 5 seconds (S27: NO, S28: Y
ES) The control is ended (S17).
If the card 40 is inserted (S27: YES),
The error history is displayed on the display unit 32 (S29). Thereafter, when the IC card 40 is removed (S30:
(NO) The display section 32 blinks "CL" for 5 seconds (S3
1) Informing that the error history can be deleted. If the IC card 40 has not been inserted again during the 5 seconds (S32: NO, S33: YES), the control is terminated (S17), but the IC card 40 is not inserted within the 5 seconds.
Is inserted (S32: YES), the stored error history is deleted (S34), and the control is terminated (S32).
17).

On the other hand, if the resident code is "002" in step 20 (S20: 002), it is determined that the card is a clear card, and the card No. The balance stored every time is displayed on the display unit 32 (S35). After that, IC
When the card 40 is removed (S36: NO), "UL" is blinked on the display section 32 for 5 seconds (S37) to notify that the balance and the resident code can be erased.
If the IC card 40 has not been inserted again during the five seconds (S38: NO, S39: YES), the control is terminated (S17), but if the IC card 40 has been inserted during the five seconds. (S38: YES), the stored balance and the resident code are deleted (S40), and the control is terminated (S17).

As described above, the water heater 1 of the present embodiment.
According to 0, when the IC card 40 having the owner data different from the stored card information is inserted, the operation is prohibited, so that the owned IC card 40 can be used only by the water heater of the owner. Therefore, even if the IC card 40 is duplicated, the damage can be minimized, and the unauthorized user can easily identify the unauthorized user, so that the unauthorized use can be suppressed. In addition, since the owner data of the IC card 40 inserted for the first time is stored as card information, it is not necessary to write different card information for each device. Further, since the hot water heater owned by the resident under the jurisdiction of the manager can be used by the dedicated card, there is no need to borrow the card owned by the resident at the time of maintenance. Moreover, in other apartments, codes other than the resident code do not match and can be made unusable, so that the security is high.

In addition, the maintenance card enables the tapping operation based on the remaining time, and sets a maximum value of the remaining time data to a minimum short time necessary for the maintenance work so that a large amount of gas cannot be used. In addition, it is possible to prevent fraud, and it is possible to reliably obtain the time required for maintenance regardless of the amount of combustion or the like. Further, the balance of the IC card 40 is set to the card No. by the card control unit 33. When the IC card 40 is broken down or lost, the stored balance can be displayed to take measures such as refund of the balance, and the operation switch and the like can be separately displayed by inserting the maintenance card. Since there is no need to provide them, they can be made inexpensive and compact. Further, by switching the mode by inserting the maintenance card or the clear card within 5 seconds after the removal, a plurality of functions can be switched with one type of card without providing an operation switch for mode switching. This is convenient because the types of cards can be reduced. Furthermore, when a resident moves or refunds the balance, the balance and the resident code are erased, so that the resident code can be changed so that the card used before can no longer be used. Can be prevented. In addition, only the resident code is erased, and the other codes need to be verified as before, and the range in which the card information can be changed is limited, thus preventing unauthorized use compared to erasing all data. it can.

Further, compared to the conventional water heater, the IC card 40
Card device 30 for reading and writing data
And a simple configuration in which the control processing of the hot water supply control unit 15 is slightly changed, it is possible to realize a system in which the usage fee of the appliance is collected in advance, so that, for example, a water heater such as a one-room apartment can be used. In a case where only gas is used, if the manager pays the gas charge for the entire apartment to the gas supplier in a lump and collects the usage fee of the appliance from each resident in advance and updates the balance data In addition, labor costs can be greatly reduced by eliminating gas meter reading and fee collection for each resident. Moreover, if a gas meter for meter reading is provided for meter reading of the entire condominium, it is not necessary to provide one for each resident, and the gas meter itself is expensive, so the installation cost for new construction etc. is greatly reduced. Can be reduced. In addition, by calculating the usage fee based on the required amount of heat calculated for the hot water temperature control, the fee can be collected fairly according to the usage status and frequency, and a device for measuring the gas amount, etc. Does not need to be newly added.

If the card device 30 is never connected, no restriction based on the usage fee is made, so that the water heater is shared between the usage mode requiring the restriction and the usage mode not requiring the restriction to reduce the manufacturing cost. be able to. In addition, once the card device 30 is connected, restrictions based on the usage fee are always performed after that, so that unauthorized use such as using gas without connecting the card device 30 even in a usage mode requiring restriction is prevented. Be able to
For example, if you want to test the operation when the instrument is initially installed, I
This is convenient because there is no need to insert the C card 40. When the balance is less than 100 yen, "0" blinks to indicate that the balance is running low, so that the user runs out of gas and the gas suddenly becomes unavailable. Can be reduced. In addition, by providing the read / write section 31 separately from the instrument main body, even if the instrument main body is installed outdoors, the read / write section 31 can be installed indoors, which is convenient.

Further, by using the IC card 40 as a storage medium and manually inserting the read / write section 31 into the storage medium, the structure of the card device 40 can be simplified and made compact. Furthermore, by using the IC card 40, the card is more resistant to repeated use than a magnetic card, and when the balance becomes low, the same card can be used for a long time by updating the data, thereby reducing the card issuing cost. can do.

In the present embodiment, the prepaid amount is stored as the balance data. However, the present invention is not limited to this. For example, the data may be stored as a consumable heat amount or an available gas amount. Any corresponding data may be used. Further, in this embodiment, the usage fee is calculated based on the required heat quantity obtained by the hot water temperature control. However, the present invention is not limited to this. For example, the heat quantity given to the water from the detected values of the hot water temperature, the incoming water temperature, and the incoming water flow rate. May be calculated, and the usage fee may be calculated based on this value. In other words, the usage fee may be a value corresponding to the calorific value of the burner 14. Further, in this embodiment, the IC card 40 is used as the storage medium, but the present invention is not limited to this, and a magnetic card may be used, for example. Also,
The card device 30 may have a function of changing the set temperature of the water heater 10 and a function of displaying the set temperature. Further, in this embodiment, the dedicated card is usable if all the codes other than the resident code match by comparing the owner data with the card information, but the present invention is not limited to this. It may be usable without being used.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, in the present embodiment, only the water heater 10 is limited. However, the present invention is not limited to this. For example, a gas cutoff device is provided in a supply source that supplies gas to a plurality of gas appliances, and the amount of gas supplied from the supply source is reduced. The balance may be subtracted accordingly and the gas may be shut off when the balance becomes zero.

[0037]

As described in detail above, claim 1 of the present invention
According to the gas supply control device described above, the mode is switched based on the timing of inserting and removing the special card, so that there is no need to provide an operation switch or the like for switching the mode, and the device can be made inexpensive. Also, since the same card can be used to switch to a plurality of modes, there is no need to prepare many types of special cards. Furthermore, if a special card is owned only by an administrator, for example,
It is possible to enhance the security by making the system incapable of mode switching for general users.

Further, according to the gas supply control device of the second aspect of the present invention, for example, by storing the error history and the like as information data in the memory, the error history stored in the memory is displayed on the display unit during maintenance. This is convenient because it can be displayed and confirmed, and can be erased from the memory when it is no longer needed.

Further, according to the gas supply control device of the third aspect of the present invention, the data display mode can be switched to the data erase mode by a simple operation such as removing the special card and reinserting it within a predetermined time. Therefore it is convenient.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a water heater as one embodiment.

FIG. 2 is a memory map of an EEPROM of a card control unit and an IC card.

FIG. 3 is a flowchart illustrating a control process performed by a hot water supply control unit.

FIG. 4 is a flowchart illustrating a control process performed by a hot water supply control unit.

FIG. 5 is a flowchart illustrating a control process performed by a hot water supply control unit.

FIG. 6 is a flowchart illustrating a control process performed by a hot water supply control unit.

[Explanation of symbols]

10 hot water heater 11 hot water supply channel 12 hot water supply channel 1
3: heat exchanger, 14: burner, 15: hot water supply control unit,
16 ... flow rate sensor, 17 ... incoming water temperature sensor, 18 ... outgoing water temperature sensor, 30 ... card device, 31 ... read / write section, 32 ... display section, 33 ... card control section, 40 ...
IC card.

Claims (3)

[Claims] 1. A gas supply control device for reading balance data from a prepaid card storing balance data corresponding to a prepaid amount and enabling supply of fuel gas based on the balance data. A gas supply control device which operates in a designated mode when a special card for maintenance or the like is inserted, and shifts to another mode based on the timing of removing and inserting the special card from that state. . 2. A memory for storing various information data,
A display section for displaying the information data, a data display mode for displaying the information data on the display section at a timing of inserting and removing the special card, and a data erasing mode for erasing information data stored in the memory. The gas supply control device according to claim 1, wherein the gas supply control device is switched over. 3. The gas supply control device according to claim 2, wherein the mode is switched to the data erasing mode when the special card is removed and reinserted within a predetermined time during the data display mode.