JPH07177668A - Final discharge voltage setting method for battery and electronic appliance employing it - Google Patents

Abstract

PURPOSE:To take out power effectively from a battery by varying the final discharge set voltage of the battery based on the value of working current of an electronic appliance. CONSTITUTION:A resistor 30 is connected with the output terminal at the battery section 22 of a facsimile. A first A/D converter 31 transmits the data of voltage value VB1 on the battery section 22 side concerning the resistor 30 to the system control section 19 and a second A/D converter 32 transmits the data of voltage value VB2 on the opposite side to the battery section 22 concerning the resistor 30 to the system control section 19. The system control section 19 calculates the value of current flowing through the battery section 22 based on the voltage values received from the first and second A/D converters 31, 32 and controls the system depending on the current value thus calculated. This constitution allows to takeout power effectively from the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a discharge end voltage of a battery and an electronic device to which the same is applied, and more particularly to a discharge end voltage setting technique capable of effectively extracting power from a battery which is a power source member. Is.

[0002]

2. Description of the Related Art In recent years, some of facsimile machines and other electronic devices have been downsized, and portable types have been used. What is important in such a portable type electronic device is that the battery, which is a power source member, lasts a long time and the power can be efficiently extracted. Among them, a facsimile machine must perform a recording operation that requires a large current at the time of reception, in addition to a reading operation and a transmission operation. Therefore, the battery is easily exhausted. Is an important factor in determining the performance of the facsimile machine. As a conventional example of a facsimile apparatus using such a battery as a power source member, there is one as shown in FIG. In this figure, reference numeral 1 is a battery as a power source member, and 2 is a DC / DC for adjusting the DC voltage which is the output of the battery 1.
It is a DC converter, and the battery output passing through this DC / DC converter 2 is sent to each functional unit of the facsimile apparatus. Reference numeral 3 is a modem for modulating / demodulating image data, 4
Is a recording head for recording an image, 5 is a motor for mechanically driving recording paper feed, and 6 is a controller for controlling the operation of each functional unit of the facsimile apparatus. An A / D converter 7 is provided between the battery 1 and the controller 6, and the voltage value VB of the battery 1 is A / D converted and sent to the controller 6.

The controller 6 has a function unit for setting the discharge end voltage of the battery 1, and whether or not the voltage value VB of the battery 1 input through the A / D converter 7 has reached the discharge end voltage. When the discharge end voltage is reached, a command is issued to each functional unit of the facsimile machine to stop the operation.

The discharge end voltage is generally determined as follows depending on the number of batteries 1 used (the number of series). In the case of 1 to 6 (the number of batteries × 1.0) V …………………… (1 formula) In the case of 7 to 20 {(the number of batteries-1) × 1.2} V ……… (2 formulas) Therefore, Given that the number of batteries is N, the discharge end voltage and the voltage per unit cell for various N are calculated as follows. Number of batteries End-of-discharge voltage Voltage per unit cell 8 8.4 V 1.05V 10 10.8 V 1.08V 12 13.2 V 1.10V 14 15.6 V 1.11V Moreover, if a large current is applied to the circuit, the battery 1 will wear out quickly and end its life. On the other hand, it is clear that the life of the battery 1 lasts for a long time if a small current is passed through the circuit. FIG. 13 is a graph showing the relationship between the number of the batteries 1 used and the discharge end voltage and the relationship between the flowing current and the battery life. It can be seen from this figure that the higher the number of batteries 1 used in series, the higher the discharge end voltage (that is,
This is disadvantageous to the user because the discharge end voltage is reached earlier.) The smaller the number of series, the lower the end voltage. Looking at the life of the battery, the life of the battery reaches 1 with the passage of time regardless of the current value used, but the life becomes shorter faster with a large current. Particularly when used with a large current, the voltage of the battery 1 drops in an extremely short time, and the discharge end voltage obtained by the above equations 1 and 2 is reached before 100% of the energy is used up.

In the conventional example as shown in FIG. 12, when the battery 1 is used in electronic equipment such as a facsimile machine,
The discharge end voltage obtained by the above equation 1 or equation 2 is set in the controller 6 as a constant voltage. And FIG.
As shown in FIG. 4, the controller 6 takes in the voltage value VB of the battery 1 via the A / D converter 7 and detects it in the processing step (hereinafter simply referred to as step) ST51, and in the subsequent step ST52, the battery 1 It is checked whether the voltage value VB of the above is equal to or higher than the set discharge end voltage value. If the voltage value VB of the battery 1 is not equal to or higher than the set discharge end voltage value, the operation of the modem 3 and the recording head 4 is controlled and step ST
Returning to 51, the voltage value VB of the battery 1 is detected. On the other hand, if it is determined in step ST52 that the voltage value VB of the battery 1 is equal to or higher than the set discharge end voltage value, the operation of the entire device is stopped in step ST53.

[0006]

However, in the above-mentioned conventional method for setting the discharge end voltage of the battery and the electronic equipment to which the method is applied, the discharge end voltage of the battery 1 used therein is set to a constant value. Therefore, especially when the electronic device is used with a large current, and the number of batteries used is large and the value of the discharge end voltage is set to be high, the voltage of the battery 1 is promptly changed to the discharge end voltage. Therefore, the energy taken out from the battery 1 becomes small. For this reason, for example, in the case of a facsimile machine, a problem that the number of recorded sheets is reduced occurs. Further, in order to maintain the life of the battery 1, it is assumed that a voltage range up to a portion before reaching the discharge end voltage with a large current, that is, a case where, for example, 10 battery packs are incorporated and a 4 amp current is used, When the electric power is repeatedly extracted in the range of P to Q of the 4-ampere curve in 11, the battery 1 itself has a characteristic that energy up to about 25% of the total energy that can be extracted from the battery is extracted. Attached, a so-called memory effect occurs. Due to this memory effect, when it is attempted to use another current, for example, 0.5 amperes, the energy of the battery 1 is 25% although there is a sufficient margin until the discharge end voltage is reached. An unfavorable phenomenon occurs in which the battery voltage drops sharply when the battery is taken out.

The present invention has been made in view of the above problems, and an object thereof is a method of setting a discharge end voltage of a battery which can effectively take out power from a battery which is a power source member, and a method for setting the same. It is to provide an applied electronic device.

[0008]

In order to achieve the above object, the present invention provides a battery for a power source, a cutoff voltage setting means for setting a discharge cutoff voltage of this battery, and a battery voltage reaching a discharge cutoff voltage. Then, the gist is that the set value of the discharge end voltage of the electronic device provided with the control means for stopping the operation of the electronic device is made variable according to the value of the used current. Further, it is a gist of the above configuration that the set value of the discharge end voltage can be changed from a high value to a low value as the used current increases.

[0009]

According to the present invention, with the above configuration, when the current used in the electronic device is small, the discharge end voltage is set to a constant value calculated by the formula for obtaining this discharge end voltage. However, when a current value larger than a certain current value is used, the set value of the discharge cutoff voltage is set to a value smaller than the value obtained by the above calculation formula. Even if the end-of-discharge voltage is set in this way, the battery releases energy without causing any over-discharging and activates electronic devices, so that the energy of the battery can be effectively taken out, and the life of the battery is minimized. Can be extended. Further, since the set value of the discharge end voltage can be varied depending on the used current value, the repeated battery does not perform the discharging action in the same voltage range, and the memory effect of the battery is prevented from occurring.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a portable facsimile apparatus which is an example of an electronic apparatus to which the method for setting the final discharge voltage of a battery according to the present invention can be applied. The facsimile device 10 is capable of facsimile communication using a battery as a power source and a wireless line. In FIG. 1, reference numeral 11 is a reading section for reading a document, 12 is a coding / decoding section for performing coding or decoding processing of image data, 13 is a modem for modulating / demodulating facsimile transmission or reception signals, and 14 is this facsimile apparatus 10. And a wireless line, an interface for wireless communication, 15 is an antenna for transmitting and receiving radio waves for facsimile communication, 16 is a recording unit for outputting received image data as hard copy, and 17 is a recording unit 16 A sensor unit that detects paper and the like. Reference numeral 18 is an operation unit for performing various operations such as transmission and reception, and 19
Is a system control unit of a program control system for controlling the entire facsimile apparatus 10, 20 is a read only memory (ROM) for storing fixed information such as programs of the system control unit 19, and 21 is a temporary storage for various data. Writable memory (R
AM), 22 is a battery unit serving as a power source member, and 23 is a reading unit 11 and a recording unit 16 which are supplied with electric power from the battery unit 22.
Reference numeral 24 denotes a DC / DC converter that adjusts the DC voltage output from the battery unit 22. The battery unit 22 is for supplying operating power of each unit of the facsimile apparatus 10, and a predetermined number of batteries 1 are set in accordance with the standard of the facsimile apparatus 10.

In the present invention, as a result of various experiments conducted on the discharge end voltage of the battery 1, this discharge end voltage is
As described in the description of the prior art, it is basically determined by the number of batteries set (1 formula and 2
It has become clear that there is a close relationship between the discharge end voltage and the working current.
FIG. 2 is a graph showing the relationship between the discharge end voltage and the used current. This graph shows the relationship between the used current and the discharge cutoff voltage when 10 sets of batteries are used as a power supply member. The horizontal axis shows the value of the used current in logarithm and the vertical axis shows the discharge cutoff voltage. Represents the value of.
As shown in FIG. 2, the discharge end voltage when 10 batteries are used is (10-1) × 1.2 = 10.8 (V) from the above formula 2. The discharge cutoff voltage of 10.8 (V) is 0.8 after the current used is extremely small.
It is effective in the range up to about (A) (range of RS in FIG. 2). However, when the working current becomes larger than the range of R-S, the discharge end voltage gradually decreases, and the discharge end voltage becomes 2
Even if the battery 1 is used, the voltage is sufficiently recovered until the voltage becomes lower than the voltage value calculated by the formula, and the life is not expired. Therefore, the energy of the battery 1 can be effectively taken out by changing the set value of the discharge end voltage in the facsimile apparatus according to the graph shown in FIG. The present invention is based on such a theory, and various examples as described below will be described.

FIG. 3A is a block diagram showing a first embodiment of the present invention in which the current value flowing through the battery 1 is detected and the set value of the discharge end voltage is made variable. In this embodiment, reference numeral 13 is a modem, 16 is a recording unit, 19 is a system control unit, 22 is a battery unit, 23 is a drive unit, and 24 is DC.
In the / DC converter, these functional units have the same roles as the corresponding functional units of the facsimile apparatus shown in FIG. In this embodiment, a resistor 30 is provided in the circuit near the output terminal of the battery section 22 of the facsimile apparatus 10. Then, the system control unit 19 has a first A / D converter 31 for transmitting data of the voltage value (VB1) on the battery unit 22 side to the resistor 30, to the system control unit 19,
The voltage value (V
The second A / D converter 32 for transmitting the data of B2) to the system control unit 19. The system control unit 19 calculates the current value flowing through the battery unit 22 based on the voltage values from the first and second A / D converters 31 and 32,
The control operation corresponding to the current value thus obtained is performed. Further, the battery control section 22 sends information about the number of the currently set batteries 1 to the system control section 19. Alternatively, such information on the number of batteries may be input as data to the system control unit 19 at the time of manufacturing the facsimile device.

Although 30 is a resistor, it may be a transistor. The block configuration of this embodiment is the same even if the configuration is (b) or (c).

3A to 3C are different in that the battery 22, the resistor 30, and the first A / D converter 3 are different.
The respective arrangements of the first and second A / D converters 32 are shown. further,
In FIG. 3C, the second A / D converter 32 not only detects the voltage, but also calculates the difference between the voltage values before and after the resistor 30. The discharge end voltage detection and device stopping operation in the facsimile apparatus having such a configuration will be described below. FIG. 4 is a flowchart showing a processing procedure in the above operation. When this operation starts, the system control unit 19 detects the battery voltage VB1 based on the data from the first A / D converter 31 in the processing step (hereinafter simply referred to as step) ST1. Next, in ST2, the system control unit 19 detects the circuit voltage VB2 lowered by the resistor 30 based on the data from the second A / D converter 32. These voltages VB1 and VB2
Then, the system control unit 19 then proceeds to step ST.
In step 3, VB1-VB2 is calculated, and the value of the current flowing through the battery section 22 is calculated from this calculation result, and the discharge end voltage corresponding to the current value is calculated in step ST4. This calculation is executed based on the graph shown in FIG. That is, if the current value obtained by the calculation result in step ST3 is about 0.8 amperes or less, the discharge end voltage is set to 10.8 volts. However, when the current value is higher, for example, 4 amperes, the discharge end voltage is set to 6.8 volts. In an electronic device such as the facsimile machine 10, there is a large difference in the current value used between the transmission operation and the reception / recording operation, and the discharge end voltage is set according to each operation. When the discharge end voltage is calculated, the system control unit 19 checks in step ST5 whether the battery voltage VB1 is larger than the previously obtained discharge end voltage, that is, VB1 ≧ discharge end voltage. , VB1 is equal to or higher than the discharge end voltage, the process returns to step ST1, while if it is determined that VB1 is not equal to or higher than the discharge end voltage, step ST1.
In step 6, the facsimile machine is stopped. As described above, over-discharging of the battery 1 is prevented and the battery life can be maintained.

FIG. 5 is a block diagram showing a second embodiment of the present invention in which the discharge end voltage is set according to the ratio of black data in the entire image data during the recording operation of the facsimile apparatus 10. In this figure, reference numeral 33 is the first A / D converter 3 in the first embodiment.
Similar to 2, the A / D converter for transmitting the data of the voltage value VB of the battery 1 to the system controller 19, and the reference numeral 34 is a black ratio counter for calculating the black ratio in the image data received through the modem. The other structure is similar to that of the first embodiment.

The discharge end voltage detection and device stopping operation in the facsimile apparatus having such a configuration will be described below. FIG. 6 is a flowchart showing a processing procedure in the above operation. When this operation starts, the system control unit 19 proceeds to step ST11 to determine the black ratio counter 3
4 is operated to count the black ratio in the received image data. Then, in step ST12, step S
The discharge end voltage for the black ratio obtained at T11 is calculated. This calculation is also carried out based on the graph shown in FIG. 2 similarly to the calculation of the discharge end voltage in the first embodiment. Even in the same recording operation in an electronic device such as the facsimile device 10, there is a large difference in the current value used when the received image data is all black and when it is all white, and it corresponds to each operation. The discharge end voltage is set. Next, in step ST13, the system control unit 19 determines the battery voltage VB based on the data from the A / D converter 33.
To detect. Next, in ST14, it is checked whether or not the battery voltage VB is higher than the previously obtained discharge end voltage, that is, VB ≧ discharge end voltage, and if VB is equal to or higher than the discharge end voltage, the process of step ST11 is performed. On the other hand, if it is determined that VB is not equal to or higher than the discharge end voltage, the process returns to step S
At T15, the facsimile machine is stopped.
As described above, over-discharging of the battery 1 is prevented and the battery life can be maintained. Since the second embodiment sets the discharge end voltage based on the black ratio of the received image data, the setting of the discharge end voltage is effective in the recording operation, and other operations (for example, reading, (Sending operation)
Regarding the above, the first embodiment may be applied.

7 and 8 are views showing a third embodiment of the present invention in which the discharge end voltage is set according to the operation mode of the facsimile apparatus 10. In this embodiment, either configuration of the first and second embodiments may be used, and in particular, it is sufficient that the A / D converter 31 or 33 for detecting the battery voltage is commonly provided. Yes, the system control unit 1
The discharge end voltage is set based on the processing operation of 9. FIG. 7 is a flow chart for explaining the operation of setting the discharge end voltage.

When this operation starts, the system control section 19 determines in step ST21 what the current operation mode of the facsimile apparatus 10 is. Then, in step ST22, the discharge end voltage for the mode determined in step ST21 is calculated. This calculation is executed based on the graph shown in FIG. In this figure, the graph showing the relationship between the current value and the battery voltage value is the same as that in FIG. As is clear from this graph, the current value used when the facsimile apparatus is in the standby state (shown by F in FIG. 8) is 0.08 to 0.0.
It is near 9 amps and is in read operation (see FIG. 8).
Medium G) is around 0.9 amps. Further, during the recording operation (indicated by H in FIG. 8), when the recorded image data is all white, it is around 0.7 amperes, and when all the image data is black, it is 6 amps.
It is near ampere. Thus, the facsimile machine 10
There is a big difference in the current value to be used between the sending operation and the receiving and recording operations, and the same recording operation when the received image data is all black and all white. The discharge end voltage is set. Next, in step ST23, the system controller 19 determines the battery voltage V based on the data from the A / D converter (31 or 33).
Detect B. Next, at ST24, the battery voltage VB
Is greater than the discharge end voltage previously obtained, that is, whether VB ≥ the discharge end voltage is checked. If VB is equal to or higher than the discharge end voltage, the process returns to step ST21 while VB is discharged. If it is determined that the voltage is not higher than the final voltage, step S
At T25, the facsimile machine is stopped.
As described above, over-discharging of the battery 1 is prevented and the battery life can be maintained.

FIGS. 9 to 11 are views showing a fourth embodiment of the present invention in which the discharge end voltage is set by catching the change in the battery voltage when the recording head enable is turned off in the recording mode of the facsimile apparatus 10. Is. Unlike the first and second embodiments, this embodiment does not require a special function unit, and even if the block configuration is the same as that of the conventional facsimile apparatus, the discharge end voltage of the discharge end voltage is changed based on the processing operation of the system control unit 19. Settings are made. FIG. 9 is a flowchart for explaining the operation of setting the discharge end voltage.

When this operation is started, the system controller 19 turns on the enable of the recording head in step ST31 as shown in FIG. 11 (b).
By this enable-on operation, a current is discharged from the battery, and a current corresponding to the difference in maximum load flows to the recording head as shown in FIG. 11 (c). While the current is flowing through the recording head, the battery voltage VB is detected in step ST32, the enable width is calculated in step ST33, and if this enable width is obtained, it is checked in step ST34 whether or not the time has expired. This check operation is repeated until the time is over, and when the time is detected, the enable is turned off in the next step ST35. By this enable-off, the battery recovers its voltage as shown in FIG. 11 (a) when the current is no longer released and rises by a voltage corresponding to VOFF in the figure. Therefore, in step ST36, the recovered voltage VB is To detect. Here, since the difference between the voltage when enable is turned on and the voltage when enable is turned off, that is, how much battery voltage is restored by enable off, is known in advance. The voltage in use can be predicted by detecting it. Therefore, during a certain recording operation, (a) to (b) in FIG.
Recording is performed within the range of (all black image data was not recorded), and (c) to (d) in another recording operation after that.
In the range (in this case, all black image data was not recorded), and in the next another recording operation, the range from (e) to (f) (in this case Recording is performed with (there was black image data), and the voltage was restored to (g) when the recording was completed. For example, voltage detection is performed in consideration of voltage drop due to current discharge every recording operation. . Then, the system control unit 19 checks whether or not the battery voltage VB is higher than the preset discharge end voltage in ST37, that is, VB ≧ discharge end voltage in consideration of the battery voltage recovery as described above. If VB is equal to or higher than the discharge end voltage, the process returns to step ST31, while if it is determined that VB is not equal to or higher than the discharge end voltage, step S31.
At T38, the facsimile machine is stopped.
As described above, over-discharging of the battery 1 is prevented and the battery life can be maintained.

[0021]

As described above, according to the present invention,
In various modes, the set value of the cutoff voltage is made variable according to the value of the current used during the operation of the electronic device, and the operation of the electronic device is stopped based on the set discharge cutoff voltage. It has become possible to operate electronic devices while effectively taking out.

[Brief description of drawings]

FIG. 1 is a block diagram showing a facsimile device as an example of an electronic device to which a method of setting a discharge end voltage of a battery according to the present invention is applied.

FIG. 2 is a graph showing the relationship between the battery current and the discharge end voltage for explaining the principle of the present invention.

FIG. 3A is a block diagram showing a first embodiment of an application example of the discharge end voltage setting method of the present invention in a facsimile apparatus. FIG. 3B is a block diagram showing a second block configuration of the first embodiment. (C) A block diagram showing a third block configuration in the first embodiment.

FIG. 4 is a flowchart for explaining the operation of the first embodiment.

FIG. 5 is a block diagram showing a second embodiment of an application example of the discharge end voltage setting method of the present invention in the facsimile device.

FIG. 6 is a flowchart for explaining the operation of the first embodiment.

FIG. 7 is a flowchart for explaining the operation of the third embodiment of the present invention.

FIG. 8 is a graph illustrating the principle of the third embodiment of the present invention.

FIG. 9 is a flowchart for explaining the operation of the fourth embodiment of the present invention.

FIG. 10 is a graph illustrating the principle of the fourth embodiment of the present invention.

FIG. 11 (a) is a diagram for explaining a change in the battery voltage ascending / descending according to ON / OFF of enable in the fourth embodiment of the present invention. (B) Turning ON / OFF of enable in the fourth embodiment of the present invention. The figure which represents (c) The figure explaining the change of the current load with turning ON / OFF of the enable in the 4th Example of this invention.

FIG. 12 is a block diagram showing a facsimile apparatus adopting a conventional discharge end voltage setting method.

FIG. 13 is a flowchart illustrating the operation of a conventional facsimile device.

FIG. 14 is a graph diagram illustrating a discharge end voltage of an assembled battery used in a conventional electronic device and a voltage drop due to use.

[Explanation of symbols]

 13 modem 16 recording unit 19 system control unit 22 battery unit 23 driving unit 24 DC / DC converter 30 resistors 31, 32, 33 A / D converter 34 black ratio counter

Claims (8)

[Claims] 1. A battery used as a power source for an electronic device, and an end voltage setting means for setting a discharge end voltage of the battery,
And a control unit for stopping the operation of the electronic device when the battery voltage reaches the discharge end voltage, the control unit changing the set value of the end voltage according to the value of the current used during the operation of the electronic device with respect to the end voltage setting unit. A method for setting the discharge end voltage, which is characterized in that 2. The method of setting the discharge end voltage according to claim 1, wherein the set value of the discharge end voltage is changed from a high value to a low value as the working current increases. 3. A battery used as a power source, a resistor provided on the output side of the battery, a first voltage detecting means for detecting a voltage on the battery side with respect to the resistor, and a resistor with respect to the resistor. Second voltage detecting means for detecting the voltage on the opposite side of the battery,
And a control unit that sets the discharge end voltage based on the detection results of the first and second voltage detection units and stops the operation of the electronic device when the battery voltage reaches the discharge end voltage. An electronic device characterized in that the set value of the discharge end voltage is made variable according to the value of the operating current during operation. 4. A battery used as a power source, a resistance means provided on the ground side of the battery, a first voltage detection means for detecting a voltage between the resistance means and the battery side, and an output of the battery. Side voltage detection means for detecting the side voltage and the discharge end voltage is set based on the detection results of the first and second voltage detection means, and when the battery voltage reaches the discharge end voltage, the electronic device operates. And a control means for stopping the electronic equipment, wherein the control means varies the set value of the discharge end voltage according to the value of the current used during the operation of the electronic equipment. 5. A battery used as a power source, a resistance means provided on the output side of the battery, a voltage on the battery side with respect to the resistance means, and a voltage on the opposite side of the battery with respect to the resistance means. Difference calculating means for detecting the difference between the battery voltage and the voltage detecting means for detecting the voltage on the battery side with respect to the resistance means, and the discharge end voltage based on the calculation result of the difference calculating means. And a control means for stopping the operation of the electronic device when the voltage detection means detects that the discharge end voltage has been reached, the control means being a set value of the discharge end voltage depending on the value of the current used during the operation of the electronic device. An electronic device characterized by being able to change. 6. A battery used as a power supply, a voltage detecting means for detecting the voltage of the battery, a black ratio counter for counting the ratio of black data in the recorded image data, and a data based on the data from the black ratio counter. And a control means for setting an end-of-discharge voltage and stopping the operation of the electronic device when the battery voltage reaches the end-of-discharge voltage, the control means changing the set value of the end-of-discharge voltage according to the count value of the black ratio counter. An electronic device, comprising: comparing data from the voltage detector with a discharge end voltage to determine whether to stop the operation. 7. A battery used as a power source, a voltage detecting means for detecting the voltage of the battery, an operation mode of the self-device, and setting a discharge end voltage according to the mode, and the voltage detector. An electronic device, characterized in that it judges whether or not to stop the operation by comparing the data from the data with the discharge end voltage. 8. A battery used as a power source and a voltage of the battery when the recording head is operated when the enable is turned off are detected, and the operating battery voltage is determined in advance from the detected off voltage. An electronic device comprising: a control unit that determines whether or not a discharge cutoff voltage is reached, and the control unit determines whether or not to stop the operation of the device based on the determination result.