JP2019215821A - On-vehicle device and control method - Google Patents

Abstract

To provide a technique for accurately performing processing at the time of voltage drop.SOLUTION: An on-vehicle device which receives the supply of electric power from a power supply provided in a vehicle includes: a plurality of functional units which function by receiving the supply of electric power; a voltage detection unit for detecting a voltage value of the electric power supplied from the power supply; and a stop control unit which performs processing to stop all the functional units when the voltage value is less than a first threshold on the basis of the voltage value of the electric power supplied from the power supply and then, performs processing to stop a specific functional unit when the voltage value is less than a second threshold higher than the first threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-vehicle device and a control method.

  2. Description of the Related Art Conventionally, a vehicle is equipped with a plurality of electrical components that operate using a vehicle-mounted battery (hereinafter, also simply referred to as a “battery”) included in the vehicle as a power source. It is desirable that power be supplied to these electrical components at a predetermined voltage. However, in a vehicle, operation of electrical components that consume a relatively large amount of power, such as deterioration of an onboard battery, running in a cold region, and a self-starter, a compressor, or a motor. The voltage of the supplied power may fluctuate due to factors such as the above. If the voltage of the supplied power drops significantly during the operation of the electrical component, the operation of the electrical component stops.In this case, the operation stops without following the specified end sequence, and the electrical component is damaged. Sometimes. For this reason, the electrical components that may be damaged by the voltage drop start the termination sequence when the voltage of the supplied power falls below the threshold, and complete the specified termination sequence before the voltage drop becomes inoperable, Those configured to avoid damage are known. In this case, a built-in capacitor for holding the power charged in a normal state before the voltage drop is provided, and when the voltage of the supplied power falls below a threshold, the power is discharged from the built-in capacitor to complete the power until the end sequence is completed. There is also known an electrical component configured to secure the electric power.

In addition, even if the operation is stopped due to a drop in voltage, if the voltage returns to the normal voltage and a reset operation such as turning on the power is performed, a function to return to the operation state before the stop was provided. There are electrical components that have Examples of the electrical components having the function of returning to the operation state before the stop include a navigation device, an audio device, an AVN (audio / visual navigation integrated device), and the like. Further, an ECU (Electronic Control Unit) that controls an engine, a transmission, a motor, a brake, an airbag, a lamp, a power steering, a power window, an air conditioner, and the like is exemplified. Hereinafter, an electrical component having a function of returning to the operation state before the stop is also referred to as an in-vehicle device.

  The in-vehicle device includes, for example, a detection circuit that detects a voltage of power supplied from a battery, and a non-volatile memory that stores an operation state before a voltage drop. When detecting that the supply voltage supplied from the battery has decreased to a predetermined value or less, the in-vehicle device starts an end sequence and stores the operating state before the decrease in the nonvolatile memory. When the supply voltage value returns to the normal voltage and a reset operation such as turning the power off and on is performed, the in-vehicle device reads the operation state held in the nonvolatile memory and returns to the operation state before the voltage drop. . Thus, the in-vehicle device can maintain various settings (brightness, luminance, volume, display broadcast channel, etc. of the display) by the operator before the voltage drop even after the return. In addition, when music content recorded on a CD or the like is being viewed, the music content can be continuously reproduced from the viewing position before the voltage drop. The same applies when the in-vehicle device is an ECU. For example, when the ECU controls an air conditioner, the air volume, intensity, temperature, and the like set by the operator before the voltage drops can be maintained after the return.

  Note that the following patent documents exist as prior art documents that describe technologies related to the technology described in this specification.

JP 2007-224066 A

  As the functions of in-vehicle devices have become more sophisticated, the number and scale of devices to be built in have increased, and the power required to complete the termination sequence has tended to increase. However, increasing the capacity of the built-in capacitor has a problem that the product cost is increased, a design change is required to secure an arrangement space for the capacitor, and the device is enlarged.

  For this reason, it is conceivable to reduce the power supplemented by the built-in capacitor by setting a high threshold value and starting the end sequence at a stage where the voltage of the supplied power is not so low, but if the threshold value is set too high, a slight Even if the voltage fluctuates, the end sequence is started, and there is a problem that the in-vehicle device is stopped even if the voltage is not lowered so as not to operate.

  The present invention has been made in view of such circumstances, and has as its object to provide a technique for accurately performing a process at the time of a voltage drop.

In order to achieve the above object, the present invention provides:
An in-vehicle device that receives supply of power from a power source provided in a vehicle,
A plurality of functional units that function by receiving the supply of power,
A voltage detection unit that detects a voltage value of the power supplied from the power supply,
Based on the voltage value of the power supplied from the power supply, performs a process of stopping all the functional units when the voltage value is less than a first threshold, the voltage value is the first threshold And a stop control unit that performs a process of stopping the specific function unit when the value becomes lower than a second threshold value higher than the second threshold value.

  The in-vehicle device may be configured such that the stop control unit determines whether the stop control unit performs a process of stopping the functional unit based on the voltage value periodically detected by the voltage detection unit a plurality of times. May be.

  In the in-vehicle device, some of the functional units that are stopped when the voltage value becomes less than the second threshold are determined in advance according to a time required for stop or a process required for stop. You may be.

  The in-vehicle device sets a plurality of the second thresholds, and for each of the second thresholds, stops when a voltage of the power supplied from the power supply is less than the second threshold. A functional unit may be defined.

  In the in-vehicle device, when the stop control unit performs a process of stopping the function unit, the stop control unit may notify a user of the stop of the function unit.

  In the in-vehicle device, the process of stopping the function unit may be a process of storing an end sequence of the function unit or information indicating a state of the function unit in a nonvolatile memory.

In order to achieve the above object, a control method of the present invention comprises:
An in-vehicle device including one or more functional units that function by receiving power supply from a power supply provided in a vehicle,
A voltage detector detects a voltage value of the power supplied from the power supply,
Based on the voltage value of the power supplied from the power supply, performs a process of stopping all the functional units when the voltage value is less than a first threshold, the voltage value is the first threshold When the value becomes lower than the second threshold value higher than the threshold value, a process of stopping some of the functional units is performed.

  According to the present invention, a technique for accurately performing a process at the time of a voltage drop is provided.

FIG. 3 is a diagram illustrating an example of a hardware configuration of the vehicle-mounted device according to the first embodiment. It is a flowchart which shows the control method of the vehicle-mounted apparatus which concerns on 1st embodiment. FIG. 13 is a diagram illustrating a timing of detecting a signal for stopping a functional unit when a voltage of power supplied from a power supply is lower than a specific threshold value in a comparative example. In the first embodiment, when the voltage of the power supplied from the power supply is less than the first threshold and when the voltage is less than the second threshold, the timing for detecting the signal for stopping the functional unit is determined. FIG. It is a figure showing the control method of the in-vehicle device concerning a second embodiment. In the second embodiment, when the voltage of the power supplied from the power supply is less than the first threshold and when the voltage is less than the second threshold, the timing for detecting the signal for stopping the functional unit is determined. FIG.

Hereinafter, an in-vehicle device according to an embodiment will be described with reference to the drawings. The configuration of the following embodiment is an exemplification, and the in-vehicle device is not limited to the configuration of the embodiment.
<First embodiment>
[1. Device configuration〕
FIG. 1 is a diagram illustrating an example of a hardware configuration of an in-vehicle device 10 according to the present embodiment. The in-vehicle device 10 includes a control unit 11, a volatile memory unit 12, a nonvolatile memory unit 13, a power supply circuit 14, a voltage detection circuit (voltage detection unit) 15, a power holding unit 16, a function unit 17, a display unit (display) 18, a speaker. 19 is provided.

  The control unit 11 is a processing device that mainly monitors power in the vehicle-mounted device 10. The control unit 11 is also called a processor. Note that the control unit 11 includes a microcomputer. The control unit 11 expands the program stored in the nonvolatile memory unit 13 into a work area of the volatile memory unit 12 so as to be executable, and controls the peripheral devices through the execution of the program to provide a function that meets a predetermined purpose. I do. In the vehicle-mounted device 10, the control unit 11 functions as a stop control unit and provides functions such as power control and memory control by executing the program. The control unit 11 is not limited to a single processor, but may have a multiprocessor configuration. Further, a single processor connected by a single socket may have a multi-core configuration.

  The volatile memory unit 12 is a volatile storage medium in which the control unit 11 caches programs and data and expands a work area. The volatile memory unit 12 is also called a main storage device. The volatile memory unit 12 includes a RAM, a ROM (Read Only Memory), and a flash memory. The nonvolatile memory unit 13 is a nonvolatile storage medium that stores programs executed by the control unit 11 and the like, operation setting information, and the like. The nonvolatile memory unit 13 is also called an auxiliary storage device. The nonvolatile memory unit 13 is, for example, an EEPROM (Electronically Erasable Programmable ROM) or a flash memory. The nonvolatile memory unit 13 may include a hard disk drive (HDD), a solid state drive (SSD), a universal serial bus (USB) memory, an SD memory card, and the like.

The power supply circuit 14 is a circuit that generates and distributes operating power for driving each unit to be controlled, such as the functional units 17 and the display unit 18 in the vehicle-mounted device 10. In the power supply circuit 14, a power supply voltage supplied from a power supply (battery or the like) 21 is converted by a booster circuit, a DC-DC converter, or the like, and supplied to the above-described units.

The voltage detection circuit (voltage detection unit) 15 detects a voltage value of the power supplied from the power supply 21 (hereinafter, also referred to as a power supply voltage value). Examples of the voltage detection circuit 15 include a comparator circuit to which a voltage of electric power supplied from the power supply 21 is applied to an input terminal and which compares the voltage at the input terminal (power supply voltage value) with a predetermined voltage value as a threshold. . In this case, a signal indicating whether the power supply voltage value has become less than the threshold value is output as a detection result. Further, in the case of the present embodiment, a plurality of comparator circuits are provided, and the power supply voltage value is compared with a first threshold value or a second threshold value. The voltage detection circuit 15 may be an A / D (Analog-to-digital converter) converter that converts a power supply voltage value (analog amount) into a digital amount according to the voltage value. In this case, a digital signal indicating the voltage value of the input terminal is output as a detection result.

  The power holding unit 16 is charged by the power supplied from the power supply 21 and holds a predetermined amount of power. The power holding unit 16 is configured by, for example, a capacitor.

  The function unit 17 is a device that functions by receiving power supply. For example, devices such as a disk drive such as a CD and a DVD, a radio receiver, a communication unit of WiFi and Bluetooth (registered trademark), an XM receiver, a TV receiver, a GPS receiver, a navigation device, and an amplifier are exemplified. In FIG. 1, four or more functional units 17 are omitted. Note that the number of the function units 17 is not particularly limited.

  The display unit 18 is a display unit such as a liquid crystal display or an EL display element, and displays an image or the like output from the function unit 17. In this embodiment, when the control unit 11 stops the function unit 17 as described later, the control unit 11 displays a message to that effect on the display unit 18 to notify the user.

  The speaker 19 outputs an acoustic signal output from the function unit 17 as sound. In the present embodiment, when the control unit 11 stops the function unit 17 as described later, the control unit 11 outputs a voice message to that effect from the speaker 19 to notify the user.

  The switch 31 is controlled by the control unit 11 and switches between supplying (ON) and interrupting (OFF) power to each functional unit 17.

[2. Control method)
Next, a control method (power control, memory control, and the like) executed by the control unit (processor) 11 of the vehicle-mounted device 10 according to the present embodiment will be described. FIG. 2 is a flowchart illustrating a control method of the vehicle-mounted device 10 according to the present embodiment.

  When power is supplied to the vehicle-mounted device 10 by turning on the accessory power supply of the vehicle or the like, the vehicle-mounted device 10 starts the processing in FIG. In step S10, control unit 11 determines whether or not the voltage state determination timing has been reached. Here, the determination timing is, for example, a timing at which a predetermined time has elapsed from the previous determination. The predetermined time is an arbitrary value such as 1 ms to several tens ms. Further, the predetermined time may be changed according to the operation state of the vehicle or the function unit 17.

When a negative determination is made in step S10, the control unit 11 repeatedly executes the determination in step S10 until an affirmative determination is made. When the determination is affirmative in step S10, the control unit 11 proceeds to step S20, and acquires from the voltage detection circuit 15 a detection signal indicating the voltage value (power supply voltage value) of the power supplied from the power supply 21. I do. For example, when the voltage detection circuit 15 is a circuit employing a comparator circuit, the power supply voltage value is compared with each of a first threshold value and a second threshold value, and a value less than the threshold value is “Lo”, Is obtained, the detection signal for which the value in the case of is “Hi” is obtained. When the voltage detection circuit 15 employs an A / D converter, a digital signal indicating a numerical value corresponding to a power supply voltage value (analog amount) is obtained as a detection signal as a detection result.

  In step S30, control unit 11 determines whether or not the power supply voltage value is less than a first threshold. If an affirmative determination is made in step S30, the control unit 11 proceeds to step S40, stops all the functional units 17, and ends the processing in FIG. For example, a stop signal is transmitted to each functional unit 17. The functional unit 17 that has received the stop signal performs a predetermined end sequence and stops operation. For example, when the function unit 17 is a communication module such as WiFi or Bluetooth, the communication unit notifies the communication partner of the end of communication and performs a process at the end. When the functional unit 17 has a power supply circuit, and the power supply circuit supplies power to a plurality of power supply terminals such as SoC (System-on-a-Chip) with different voltage values, a stop signal is generated. Upon reception, the supply is stopped in a predetermined order (for example, in the descending order of the voltage value). When the function unit 17 is a device that records information such as images and data, recording is stopped upon receipt of a stop signal, and the file being processed is closed. At the timing when such an end sequence is completed, the control unit 11 controls the switch 31 to stop supplying power to the functional unit 17. For example, the power supply is stopped after a lapse of a predetermined time from the transmission of the stop signal.

  Although FIG. 1 shows an example in which one power supply line is shown for one functional unit 17 and one switch 31 is provided on each of the supply lines, the present invention is not limited to this. May be provided with a plurality of supply lines for supplying powers having different voltage values, and switches may be provided on the plurality of supply lines, respectively, and the control unit 11 may control these switches. As a result, when the function unit 17 is stopped, the control unit 11 performs a process of stopping power supplied to the function unit 17 in a predetermined order (for example, in the order of higher voltage value).

  In addition, as a process of stopping the function unit 17, a process of storing information indicating an operation state of the function unit 17 is exemplified. For example, when stopping the function unit 17, the control unit 11 stores (evacuates) information indicating the operation state of the function unit 17 developed in the volatile memory unit 12 in the nonvolatile memory unit 13. As a result, when the power supply voltage value returns to a normal value and a reset operation such as turning the power off and on is performed, information indicating the operation state of the functional unit 17 saved to the nonvolatile memory unit 13 (hereinafter referred to as “save”). The function unit 17 can be returned to the operation state before the stop by reading out the information (also referred to as information) and developing the information in the volatile memory unit 12. Here, as the evacuation information, for example, when the function unit 17 is a radio receiving module, information indicating the frequency (channel) set on the channel selection button, information indicating the frequency (channel) selected at the time of stoppage, etc. Is mentioned. When the function unit 17 is a music playback device such as a disk drive such as a CD or DVD or a semiconductor audio player, the evacuation information includes information indicating a song or a track being played back at the time of stoppage, a history of the played song. And the like.

  On the other hand, if a negative determination is made in step S30, the control unit 11 proceeds to step S50 and determines whether or not a stop condition based on the second threshold is satisfied. For example, when the power supply voltage value is less than the second threshold, it is determined that the stop condition is satisfied. The control unit 11 is not limited to determining whether or not the stop condition is satisfied based on one detection result (detection signal). The control unit 11 may determine the stop condition based on a plurality of periodically obtained detection results. It may be determined whether or not the condition is satisfied. For example, when the power supply voltage value is less than the second threshold value for a predetermined number of consecutive times, it may be determined that the stop condition is satisfied.

In the case of an affirmative determination in step S50, the control unit 11 proceeds to step S60 and notifies that the specific function unit 17 that is a part of the function units 17 is to be stopped. For example, the user is notified by displaying it on the display unit 18 or outputting it as a voice message from the speaker 19, as in “the radio function is stopped because a drop in the power supply voltage is detected”. Then, in step S70, control unit 11 performs a process of stopping specific function unit 17. Note that the process of stopping the function unit 17 is the same as the process described in step S40 described above. The specific function unit 17 to be stopped in step S70 is set in advance according to the time required for the end sequence, the processing required at the time of stop, power consumption, and the importance of the function. For example, the function unit 17 that takes a long time to complete the termination sequence is stopped in step S70. In step S70, the function unit 17 that needs to save the information indicating the state at the time of stopping to the nonvolatile memory unit 13 and the function unit 17 that needs to control the supply voltage are stopped. After step S70, the control unit 11 returns to step S10 and determines again whether the measurement timing has been reached. Then, when the next measurement timing is reached (Step S10, Yes), the power supply voltage value is acquired (Step S20), and when the voltage further decreases and an affirmative determination is made in Step S30, all functions are stopped. (Step S40). Note that when a negative determination is made in step S30 and an affirmative determination is made in step S50, the processing of steps S60 and S70 may be skipped if a specific functional unit has already been stopped. As described above, after stopping the specific functional unit in step S70, the control unit 11 returns to step S10 and repeats the processing of FIG. 2. If the determination in step S30 is affirmative, the control unit 11 stops all the functions. (Step S
40), and the process of FIG. 2 ends. Note that, after step S70, the process of FIG. 2 may be terminated instead of returning to step S10. For example, if a specific functional unit such as a functional unit that needs to save information indicating an operation state or a functional unit that requires a predetermined end sequence is stopped in step S70, the processing in FIG. Then, the configuration may be such that the control unit 11 does not stop the functional unit.

[3. Action / effect)
The operation and effect of the present embodiment will be described with reference to FIGS. FIG. 3 is a diagram illustrating, as a comparative example, a timing of detecting a signal for stopping the functional unit 17 when the voltage of the power supplied from the power supply becomes lower than a specific threshold. In the embodiment, when the voltage of the power supplied from the power supply becomes less than the first threshold and when the voltage becomes less than the second threshold, the timing for detecting the signal for stopping the functional unit 17 is determined. FIG. 3 and 4, the horizontal axis indicates time, the vertical axis indicates voltage, a solid line 90 indicates the voltage value of the power supplied from the power supply 21, and solid lines 91 and 92 indicate the voltage of the voltage detection circuit 15. The detection result is shown.

  In the comparative example of FIG. 3, the detection signal 91 changes from Lo to Hi at the timing T1 when the power supply voltage value becomes less than the threshold value V1, for example, less than 8.8V. Therefore, when the function units 17 are stopped based on the detection signal 91, the process of stopping all the function units 17 is started at timing T1.

  On the other hand, in the present embodiment, as shown in FIG. 4, the detection is performed at the timing T2 when the power supply voltage value becomes lower than the second threshold value V2 higher than the first threshold value V1, for example, lower than 8.95V. The signal 92 changes from Lo to Hi. 3, the detection signal 91 changes from Lo to Hi at the timing T1 when the power supply voltage value becomes lower than the first threshold value V1, for example, lower than 8.8V. When the detection signal 92 becomes Hi (Step S50, Yes), the control unit 11 stops the specific function unit 17 (Step S70). Further, when the detection signal 91 becomes Hi (Step S30, Yes), the control unit 11 stops all the function units 17 (Step S40).

As described above, at the timing T2 when the power supply voltage value decreases from the normal voltage level V3 and the power supply voltage value becomes lower than the second threshold value V2, since the power supply voltage value is not lower than the first threshold value V1, the control unit 11 Then, a negative determination is made in step S30, and if it is determined in step S50 that the stop condition is satisfied, a process of stopping only the specific functional unit 17 (hereinafter, also referred to as a stop process) is performed. Then, when the power supply voltage value becomes less than the first threshold value V1 (timing T1), the control unit 11 makes an affirmative determination in step S30, and stops all the functional units 17. Therefore, not all the stop processes are started from timing T1, but the specific function unit 17 is started from timing T2, so that the stop process is started earlier by the difference ΔT. Therefore, the stop processing can be performed for the specific function unit 17 before the power supply voltage value has completely decreased, and the necessary control at the time of stop, such as memory control or power supply control, can be reliably performed. That is, the processing at the time of voltage drop is performed accurately. In addition, it is possible to suppress an increase in the capacity of the power holding unit 16.

<Second embodiment>
FIG. 5 is a diagram illustrating a control method of the vehicle-mounted device according to the second embodiment. This embodiment differs from the above-described first embodiment in the configuration in which a plurality of second thresholds are set, and the other configurations are the same. For this reason, the same elements are denoted by the same reference numerals, and the description thereof will not be repeated.

  In the present embodiment, a threshold V21 higher than the first threshold V1 and a threshold V22 higher than the threshold V21 are set as the second thresholds.

  5, the processing in steps S10 to S40 is the same as the processing shown in FIG. 2 described above.

  If a negative determination is made in step S30, the control unit 11 proceeds to step S50A and determines whether or not a stop condition based on the second threshold value V21 is satisfied. For example, when the power supply voltage value is less than the second threshold value V21, it is determined that the stop condition is satisfied. The control unit 11 is not limited to determining whether or not the stop condition is satisfied based on one detection result (detection signal). The control unit 11 may determine the stop condition based on a plurality of periodically obtained detection results. It may be determined whether or not the condition is satisfied. For example, when the power supply voltage value is less than the second threshold value V21 continuously for a predetermined number of times, it may be determined that the stop condition is satisfied. Particularly, in the present embodiment, since the second threshold value V21 is set lower than the second threshold value V22, the number of times is set smaller than that in step S50A.

  In the case of an affirmative determination in step S50A, the control unit 11 shifts to step S60A and notifies the specific function unit 17 to stop. Then, in step S70A, control unit 11 performs a process of stopping specific function unit 17. The process of stopping the function unit 17 is the same as the process in step S40 of FIG. 2 described above. The specific function unit 17 to be stopped in step S70A is set in advance according to the time required for the end sequence, the processing required at the time of the stop, power consumption, and the importance of the function. The specific function unit 17 to be stopped in step S70A includes all the specific function units 17 to be stopped in step S100 to be described later, and may be set so as to stop another function unit 17 or Alternatively, a function unit 17 for stopping each of them may be set.

After step S70A, the control unit 11 returns to step S10 and determines again whether or not the measurement timing has been reached. On the other hand, if a negative determination is made in step S50A, the control unit 11 proceeds to step S80 and determines whether or not a stop condition based on the second threshold value V22 is satisfied. For example, when the power supply voltage value is less than the second threshold value V22, it is determined that the stop condition is satisfied. The control unit 11 is not limited to determining whether or not the stop condition is satisfied based on one detection result (detection signal). The control unit 11 may determine the stop condition based on a plurality of periodically obtained detection results. It may be determined whether or not the condition is satisfied. For example, when the power supply voltage value is less than the second threshold value V22 continuously for a predetermined number of times, it may be determined that the stop condition is satisfied. The number of times that the power supply voltage value used as the stop condition in step S80 is less than the second threshold value V22 may be different from the number of times in step S50A. For example, when the power supply voltage value is less than the second threshold value V22 continuously 10 times, it may be determined that the stop condition is satisfied. In the present embodiment, since the second threshold value V22 is set higher than the second threshold value V21 and the first threshold value V1, an erroneous determination is made by performing the determination based on the power supply voltage value for a relatively long period. The judgment is suppressed.

  In the case of an affirmative determination in step S80, the control unit 11 proceeds to step S90 and notifies that the specific function unit 17 is to be stopped. Then, in step S100, control unit 11 performs a process of stopping specific function unit 17. The process of stopping the function unit 17 is the same as the process in step S40 of FIG. 2 described above. The specific function unit 17 to be stopped in step S100 is set in advance according to the time required for the end sequence, the processing required at the time of stop, power consumption, and the importance of the function. In the present embodiment, since the second threshold value V22 is set higher than the second threshold value V21, for example, the functional unit 17 that requires a longer end sequence as compared with step S70A and the process at the end can be reliably performed. The setting is made so as to stop the function unit 17 which must be performed. After step S100, the control unit 11 returns to step S10 and determines again whether or not the measurement timing has been reached. Then, when the next measurement timing is reached (Step S10, Yes), the power supply voltage value is acquired (Step S20), and when the voltage further decreases and an affirmative determination is made in Step S30, all functions are stopped. (Step S40). Note that, when a positive determination is made in steps S50A and S80, the processing of steps S60A, S70A, S90, and S100 may be skipped if the specific functional unit has already been stopped. As described above, after stopping the specific functional units in steps S70A and S100, the control unit 11 returns to step S10 and repeats the processing of FIG. 5. If the determination in step S30 is affirmative, all the functions are reset. The operation stops (step S40), and the processing in FIG. 5 ends. Note that, after steps S70A and S100, instead of returning to step S10, the processing of FIG. 5 may be terminated. For example, if a specific functional unit such as a functional unit that needs to save information indicating an operation state or a functional unit that requires a predetermined end sequence is stopped in steps S70A and S100, the processing in FIG. May be ended so that the control unit 11 does not stop the functional unit.

  FIG. 6 illustrates a case where the function unit 17 is stopped when the voltage of the power supplied from the power supply is less than the first threshold V1 and when the voltage of the power is less than the second thresholds V21 and V22. FIG. 4 is a diagram showing timing for detecting a signal for causing the signal to be detected. In FIG. 6, the horizontal axis indicates time, the vertical axis indicates voltage, a solid line 90 indicates a voltage value of power supplied from the power supply 21, and solid lines 91, 92, and 93 indicate detection values of the voltage detection circuit 15. The results are shown.

  In the present embodiment, as shown in FIG. 6, at timing T22 when the power supply voltage value becomes lower than the second threshold value V22 higher than the second threshold value V21, for example, becomes lower than 8.95 V, the detection signal 92 changes from Lo. Hi. Further, at timing T21 when the power supply voltage value becomes lower than the second threshold value V21 higher than the first threshold value V1, for example, lower than 8.9V, the detection signal 93 changes from Lo to Hi.

  When the detection signal 92 becomes Hi (Step S80, Yes), the control unit 11 stops the specific function unit 17 (Step S100). When the detection signal 93 becomes Hi (Step S50A, Yes), the control unit 11 stops the specific function unit 17 (Step S70A). Further, when the detection signal 91 becomes Hi (Step S30, Yes), the control unit 11 stops all the function units 17 (Step S40).

  As described above, in the present embodiment, the specific functional unit is stopped at the timing T21 when the power supply voltage value falls below the second threshold value V21 and at the timing T22 when the power supply voltage value falls below the second threshold value V22. Do. For this reason, the process at the time of stopping can be performed more accurately. In particular, in the present embodiment, the determination based on the second threshold V22 set relatively high is performed based on the determination result longer than the determination based on the second threshold V21, and an erroneous determination when the threshold is set high is determined. I am holding it down. In the present embodiment, two second thresholds are set. However, the present invention is not limited to this, and three or more second thresholds may be set.

10: In-vehicle device 11: Control unit 12: Volatile memory unit 13: Non-volatile memory unit 14: Power supply circuit 15: Voltage detection circuit 16: Power holding unit 17: Function unit 18: Display unit 19: Speaker 21: Power supply

Claims (7)

An in-vehicle device that receives supply of power from a power source provided in a vehicle,
A plurality of functional units that function by receiving the supply of power,
A voltage detection unit that detects a voltage value of the power supplied from the power supply,
Based on the voltage value of the power supplied from the power supply, performs a process of stopping all the functional units when the voltage value is less than a first threshold, the voltage value is the first threshold If less than a second threshold higher than, a stop control unit that performs processing to stop some of the functional units,
An in-vehicle device comprising:   2. The stop control unit according to claim 1, wherein the stop control unit determines whether or not to perform a process of stopping the function unit based on the voltage value detected by the voltage detection unit periodically a plurality of times. 3. The in-vehicle device according to the above.   2. The function unit, which is stopped when the voltage value becomes less than the second threshold value, is partially set in advance according to a time required for stopping or a process required for stopping. Or the in-vehicle device according to 2.   A plurality of the second thresholds are set, and for each of the second thresholds, the function unit to be stopped when the voltage of the power supplied from the power supply is less than the second threshold is determined. The in-vehicle device according to claim 3.   The in-vehicle device according to any one of claims 1 to 4, wherein the stop control unit notifies the user of the stop of the function unit when performing the process of stopping the function unit.   The in-vehicle device according to any one of claims 1 to 5, wherein the process of stopping the function unit is a process of storing an end sequence of the function unit or information indicating a state of the function unit in a nonvolatile memory. An in-vehicle device including one or more functional units that function by receiving power supply from a power supply provided in a vehicle,
A voltage detector detects a voltage value of the power supplied from the power supply,
Based on the voltage value of the power supplied from the power supply, performs a process of stopping all the functional units when the voltage value is less than a first threshold, the voltage value is the first threshold When it is less than the second threshold higher than, perform a process of stopping some of the functional units,
A control method characterized by that.

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