Onboard power monitoring device

Abstract

An in-vehicle power supply monitoring device is provided that is capable of monitoring the voltage of a power supply line with respect to a plurality of threshold values ​​with a simple configuration. [Solution] The in-vehicle power supply monitoring device 1 includes multiple voltage detection terminals Ss1-Ss3 to which the voltage V of the power line Lv is input, and a single reset IC 20 that outputs reset signals Sr1-Sr3 indicating the presence or absence of an abnormality in the voltage V of the power line Lv and has the same number of reset signal output terminals Rst1-Rst3 as the number of voltage detection terminals Ss1-Ss3. When the voltage V of the power line Lv exceeds or falls below a threshold value set in advance for each of the multiple voltage detection terminals Ss1-Ss3, the single reset IC 20 switches between the presence or absence of an abnormality indicated by the reset signals Sr1-Sr3 output from the reset signal output terminals Rst1-Rst3 corresponding to the threshold value. The voltage detection terminals Ss1 and Ss2 are connected to the same power line Lv.

Description

[Technical Field]

[0001] The present disclosure relates to an in-vehicle power supply monitoring device. [Background technology]

[0002] The vehicle display device described in Patent Document 1 includes a first power supply that supplies a transformed first voltage to a processor, and a voltage determination unit that operates the first power supply normally when the first voltage is less than a first threshold voltage and stops the first power supply when the first voltage is equal to or greater than the first threshold voltage. This voltage determination unit can be, for example, a reset integrated circuit (IC) or a comparator (see paragraph 0027 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-86326 Summary of the Invention [Problem to be solved by the invention]

[0004] In the standalone reset IC described in Patent Document 1, only one threshold value can be set for a specific power supply line, and it is not possible to set multiple threshold values ​​for a specific power supply line and monitor the voltage. In addition, by using the processor's ADC (Analog-Digital Converter) port to convert the analog signal of the power supply voltage into a digital signal, it becomes possible to monitor a specific power supply voltage with the processor. However, since ADC ports, which tend to be in short supply, are used to monitor the voltage, extra ADC ports are required, which hinders the simplification of the configuration.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide an in-vehicle power supply monitoring device that is simple in configuration and can monitor the voltage of a power supply line against a plurality of threshold values. [Means for solving the problem]

[0006] In order to achieve the above object, the on-board power supply monitoring device according to the present disclosure comprises: a single voltage detection element having a plurality of voltage detection terminals for inputting voltage of a power supply line through which power is supplied, and an abnormality detection signal output terminals for outputting an abnormality detection signal indicating whether or not there is an abnormality in the voltage of the power supply line, the number of the abnormality detection signal output terminals being the same as the number of the voltage detection terminals; when the voltage of the power supply line exceeds or falls below a threshold value previously set for each of the plurality of voltage detection terminals, the single voltage detection element switches between the presence or absence of an abnormality indicated by the abnormality detection signal output from the abnormality detection signal output terminal corresponding to the threshold value; Of the plurality of voltage detection terminals, a first voltage detection terminal and a second voltage detection terminal are connected to the same power supply line. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to monitor the voltage of a power supply line with respect to a plurality of threshold values ​​with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram of a vehicle display device according to an embodiment of the present disclosure. [Figure 2] 4 is a timing chart showing the states of a voltage, a reset signal, a fault detection signal, and a vehicle display device according to an embodiment of the present disclosure. [Figure 3] FIG. 10 is a block diagram of a vehicle display device according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle display device including an on-board power supply monitoring device according to an embodiment of the present disclosure will be described with reference to the drawings. The vehicle display device is a head-up display device that displays a projected image by projecting display light onto a projection target (such as a windshield or a combiner). The vehicle display device is not limited to a head-up display device, and may be an in-vehicle meter.

[0010] 1, the vehicle display device 10 includes a reset IC 20, a control unit 30, a DC-DC converter 40, and a load 50. The reset IC 20 and the control unit 30 constitute an in-vehicle power supply monitoring device 1. The in-vehicle power supply monitoring device 1 monitors the voltage V of a single power line Lv for supplying power to the load 50, and if a low-voltage or high-voltage abnormality occurs in the voltage V, the vehicle display device 10 is shut down or operated in a safety mode.

[0011] The load 50 includes a display 51 that displays an image, a backlight unit 52 that illuminates the display 51 , and a motor 53 .

[0012] The backlight unit 52 includes a plurality of LEDs (Light Emitting Diodes) that emit illumination light. The display 51 is a TFT (Thin Film Transistor) liquid crystal panel. The display 51 receives illumination light from a backlight unit 52 and emits display light that displays an image. The motor 53 is a drive source that rotates a concave mirror (not shown) that reflects the display light toward a projection member.

[0013] The DC-DC converter 40 is a constant voltage generating unit that steps down the voltage from the vehicle-mounted power supply and supplies the stepped-down voltage V to the load 50 via the power supply line Lv.

[0014] The reset IC 20 is a power supply IC that monitors the voltage V. The reset IC 20 is of the 3ch (triple channel) type and has a plurality of SENSE terminals (voltage detection terminals Ss1 to Ss3 described later) and RESET terminals (reset signal output terminals Rst1 to Rst3). The reset IC 20 monitors the magnitude of the voltage V on a single power line Lv with respect to a plurality of threshold values, and outputs the monitoring results as reset signals Sr1 to Sr3 to the control unit 30.

[0015] The reset IC 20 includes voltage detection terminals Ss1 to Ss3, reset signal output terminals Rst1 to Rst3, a fault signal output terminal Pf, and a power supply input terminal VDD.

[0016] The power supply input terminal VDD is electrically connected to a power supply and inputs the operating power of the reset IC 20. The reset signal output terminals Rst1 to Rst3 are electrically connected to the reset signal input terminals Pi1 to Pi3 of the control unit 30, respectively, and output the reset signals Sr1 to Sr3 to the reset signal input terminals Pi1 to Pi3. The reset signals Sr1 to Sr3 switch between high and low. The low reset signals Sr1 to Sr3 indicate a voltage abnormality, and the high reset signals Sr1 to Sr3 indicate a normal voltage.

[0017] The voltage detection terminals Ss1 to Ss3 are electrically connected to a common power line Lv, respectively, and input the voltage V applied to the power line Lv. Different threshold values Th1 to Th3 are set for each of the voltage detection terminals Ss1 to Ss (3).

[0018] As shown in FIG. 2, the magnitude relationship of the threshold values Th1 to Th3 is "Th1 < Th2 < Th3". The threshold value Th1 is set lower than the rated voltage of the power line Lv, and the threshold values Th2 and Th3 are set higher than the rated voltage of the power line Lv. Here, the rated voltage refers to the maximum voltage that can be safely used under normal operating conditions in which the load 50 is designed. The threshold value Th1 is 3.0V, the threshold value Th2 is 3.8V, and the threshold value Th3 is 4.3V.

[0019] The reset IC 20 determines whether the voltage V input to the voltage detection terminal Ss1 is below a threshold value Th1, whether the voltage V input to the voltage detection terminal Ss2 is above a threshold value Th2, and whether the voltage V input to the voltage detection terminal Ss3 is above a threshold value Th3.

[0020] When the voltage V falls below the threshold Th1 (period Ta in Figure 2), the reset IC 20 outputs a low reset signal Sr1 from the reset signal output terminal Rst1, and when the voltage V is equal to or greater than the threshold Th1 (periods Tb, Tc, and Td in Figure 2), the reset IC 20 outputs a high reset signal Sr1 from the reset signal output terminal Rst1.

[0021] When the voltage V exceeds the threshold Th2 (periods Tc and Td in Figure 2), the reset IC 20 outputs a low reset signal Sr2 from the reset signal output terminal Rst2, and when the voltage V is equal to or lower than the threshold Th2 (periods Ta and Tb in Figure 2), the reset IC 20 outputs a high reset signal Sr2 from the reset signal output terminal Rst2.

[0022] When the voltage V exceeds the threshold value Th3 (period Td in Figure 2), the reset IC 20 outputs a low reset signal Sr3 from the reset signal output terminal Rst3, and when the voltage V is equal to or lower than the threshold value Th3 (periods Ta, Tb, and Tc in Figure 2), the reset IC 20 outputs a high reset signal Sr3 from the reset signal output terminal Rst3.

[0023] 1, the fault signal output terminal Pf is electrically connected to the fault signal input terminal P2 of the control unit 30 and outputs a fault detection signal Sf to the fault signal input terminal P2. The fault detection signal Sf switches between ON and OFF. An ON fault detection signal Sf indicates the presence of a fault, and an OFF fault detection signal Sf indicates the absence of a fault.

[0024] The reset IC 20 outputs an ON fault detection signal Sf from the fault signal output terminal Pf when the voltage V is within the fault range FA, and outputs an OFF fault detection signal Sf from the fault signal output terminal Pf when the voltage V is outside the fault range FA. The fault range FA is set to the range between the thresholds Th2 and Th3. The reset IC 20 determines that the voltage V is within the fault range FA when the condition that the reset signal Sr2 is low and the reset signal Sr3 is high is met, and determines that the voltage V is outside the fault range FA when this condition is not met.

[0025] As shown in FIG. 1, the control unit 30 includes a CPU (Central Processing Unit) or a GDC (Graphics Display Controller), and controls a load 50. The control unit 30 includes reset signal input terminals Pi1 to Pi3 and a fault signal input terminal P2. The reset signal input terminals Pi1 to Pi3, the fault signal input terminal P2, the reset signal output terminals Rst1 to Rst3 and the fault signal output terminal Pf are all general-purpose ports that input and output signals binarized as high or low (reset signals Sr1 to Sr3 or fault detection signal Sf).

[0026] The three reset signal input terminals Pi1 to Pi3 are electrically connected to the reset signal output terminals Rst1 to Rst3 of the reset IC 20 in a one-to-one correspondence, respectively, and the reset signals Sr1 to Sr3 are input from the reset signal output terminals Rst1 to Rst3.

[0027] The fault signal input terminal P2 is electrically connected to the fault signal output terminal Pf of the reset IC 20, and receives the fault detection signal Sf from the fault signal output terminal Pf.

[0028] The control unit 30 switches the state of the vehicle display device 10 according to the input reset signals Sr1 to Sr3 and the state of the failure signal output terminal Pf. Specifically, when the control unit 30 receives all high reset signals Sr1 to Sr3 during the period Tb in Fig. 2, it determines that the voltage V is within the normal range NA and operates the vehicular display device 10 (load 50) in the normal operation mode, which is a mode in which there are no restrictions on the operation of the load 50.

[0029] 2, when the control unit 30 receives a low reset signal Sr1 and high reset signals Sr2 and Sr3, it determines that the voltage V falls below the threshold value Th1 and shuts down the vehicle display device 10 (load 50). To shut down the vehicle display device 10, the control unit 30 stops the supply of drive power to the load 50 and then turns off the power to the vehicle display device 10.

[0030] During the period Td in FIG. 2, when the control unit 30 receives low reset signals Sr2 and Sr3 and receives a high reset signal Sr1, it determines that the voltage V exceeds the threshold value Th3 and shuts down the vehicular display device 10 (load 50) in the same manner as described above.

[0031] When the control unit 30 receives an ON fault detection signal Sf during the period Tc in FIG. 2, it determines that the voltage V is within the fault range FA and operates the vehicular display device 10 (load 50) in a safety mode. The safety mode is a mode in which the operation of the load 50 is limited. For example, in the normal operation mode, the LED light emission brightness of the backlight unit 52 can be turned on at 100%, while in the safety mode, the LED light emission brightness is limited to a limit value less than 100%. Also, for example, in the safety mode, the content of the display image of the display device 51 may be reduced or simplified compared to the normal operation mode. Also, in the safety mode, the value of the current supplied to the motor 53 may be smaller than that in the normal operation mode. In the safety mode, the operation of the load 50 may be stopped. In this case, the safety mode may put the control unit 30 into a sleep state, which allows for quicker recovery than the power-off mode after shutdown.

[0032] In this embodiment, the triple-channel type reset IC 20 is configured to monitor the magnitude of the voltage V applied to one power line Lv relative to three threshold values ​​Th1 to Th3. This type of use of the triple-channel type reset IC 20 is unusual and has its own unique features. For example, as shown in the comparative example of FIG. 3, voltage detection terminals Ss1 to Ss3 of a triple-channel reset IC 120 generally receive voltages from multiple DC-DC converters 41 to 43 that generate different voltages (e.g., 1.2 V, 1.8 V, and 3.3 V). In the reset IC 120 according to this comparative example, a threshold value is set for each power supply line to which multiple different voltages are applied, but it is not possible to set multiple threshold values ​​for the voltage of a single power supply line. In this regard, in the present embodiment, it is possible to set multiple threshold values ​​for the voltage of a single power supply line.

[0033] (effect) According to the embodiment described above, the following effects are achieved. (1) The in-vehicle power supply monitoring device 1 includes a plurality of voltage detection terminals Ss1-Ss3 to which a voltage V of a power line Lv to which power is supplied is input, and a reset IC 20, which is an example of a single voltage detection element, that outputs reset signals Sr1-Sr3 (abnormality detection signals) indicating the presence or absence of an abnormality in the voltage V of the power line Lv and has the same number of reset signal output terminals Rst1-Rst3 (abnormality detection signal output terminals) as the number of voltage detection terminals Ss1-Ss3. When the voltage V of the power line Lv exceeds or falls below thresholds Th1-Th3 set in advance for each of the plurality of voltage detection terminals Ss1-Ss3, the single reset IC 20 switches between the presence or absence of an abnormality indicated by the reset signals Sr1-Sr3 output from the reset signal output terminals Rst1-Rst3 corresponding to the thresholds Th1-Th3. Of the plurality of voltage detection terminals Ss1-Ss3, a first voltage detection terminal Ss1 and a second voltage detection terminal Ss2 are connected to the same power line Lv. With this configuration, a single reset IC 20 can monitor the voltage V of one power line Lv against multiple thresholds Th1 to Th3. Furthermore, the presence or absence of an abnormality indicated by the reset signals Sr1 to Sr3 is determined depending on whether the voltage V is high or low against the thresholds Th1 to Th3. Therefore, the reset signals Sr1 to Sr3 can be transmitted and received between the reset signal output terminals Rst1 to Rst3, which are general-purpose ports, and the reset signal input terminals Pi1 to Pi3, eliminating the need for an ADC port in the reset IC 20 and the control unit 30. Therefore, there is no need to add an ADC port, and the voltage V can be monitored against multiple thresholds Th1 to Th3 with a simple configuration.

[0034] (2) The first threshold value Th1 corresponding to the first voltage detection terminal Ss1 is set lower than the rated voltage of the power line Lv, and the second threshold value Th2 corresponding to the second voltage detection terminal Ss2 is set higher than the rated voltage of the power line Lv. This configuration makes it possible to determine both high voltage and low voltage abnormalities without using an ADC port.

[0035] (3) The third threshold value Th3 corresponding to the third voltage detection terminal Ss3 among the multiple voltage detection terminals Ss1 to Ss3 is set to a value that is higher than the rated voltage of the power supply line Lv and different from the second threshold value Th2. According to this configuration, two thresholds Th2 and Th3 can be set on the high voltage side without using an ADC port. The threshold value Th2 is set smaller than the threshold value Th3, and when the voltage V exceeds the threshold value Th3, the vehicle display device 10 is shut down, and when the voltage V is in the range between the threshold values ​​Th2 and Th3, the vehicle display device 10 is operated in a safety mode in which some of the functions of the vehicle display device 10 are limited. This prevents the vehicle display device 10 from being shut down immediately when the voltage V becomes high.

[0036] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) may be made as appropriate within the scope of the present disclosure. An example of such a modification is described below.

[0037] (Variation) In the above embodiment, the control unit 30 has three reset signal input terminals Pi1 to Pi3 that correspond one-to-one to the reset signal output terminals Rst1 to Rst3, but the three reset signal output terminals Rst1 to Rst3 may be connected to a single reset signal input terminal. In this case, a logic circuit (OR circuit) may be provided that outputs a low reset signal to the single reset signal input terminal when one or more of the three reset signals Sr1 to Sr3 become low, and outputs a high reset signal to the single reset signal input terminal when all of the reset signals Sr1 to Sr3 become high.

[0038] In the above embodiment, the reset IC 20 has three channels, but it may have four channels (quad channels), two channels (dual channels), or five or more channels. The number of thresholds can be increased or decreased depending on the number of channels.

[0039] In the above embodiment, the fault signal output terminal Pf, the fault signal input terminal P2, and the fault detection signal Sf may be omitted. In this case, when the control unit 30 receives the low reset signal Sr2 and the high reset signals Sr1 and Sr3, the control unit 30 operates the vehicular display device 10 in the safety mode.

[0040] In the above embodiment, the display 51 is not limited to a TFT-type liquid crystal display panel, but may be an organic electroluminescence display (OLED) or a DMD (Digital Mirror Device) type display device.

[0041] In the above embodiment, the type of the load 50 can be changed as appropriate, and at least one or two of the display 51, the backlight unit 52, and the motor 53 may be omitted.

[0042] The in-vehicle power supply monitoring device 1 includes a single first reset IC for the first power supply line to which a voltage V of a first voltage value (e.g., 3.3 V) is applied, but in addition to the first reset IC, a single second reset IC may also be included for the second power supply line to which a voltage V of a second voltage value (e.g., 1.8 V) different from the first voltage value is applied. In this way, a single reset IC may be provided for each of a plurality of power supply lines. Furthermore, in a single reset IC, two of the four voltage detection terminals may be connected to the first power supply line, and the remaining two voltage detection terminals may be connected to the second power supply line.

[0043] Of the thresholds Th1 to Th3, the threshold Th2 or Th3 may be omitted, in which case the reset signal output terminal Rst2 or Rst3 and the reset signal input terminal Pi2 or Pi3 may be omitted. [Explanation of symbols]

[0044] 1…In-vehicle power supply monitoring device 10...Vehicle display device 20,120...Reset IC, Ss1~Ss3...Voltage detection terminals, Rst1~Rst3...Reset signal output terminals, VDD...Power supply input terminal 30...control unit, Pi1 to Pi3...reset signal input terminal, P2...fault signal input terminal, 40, 41 to 43...DCDC converter 50...load, 51...display, 52...backlight unit, 53...motor FA...fault range, V...voltage, NA...normal range, Ta~Td...period, Pf...fault signal output terminal, Sf...fault detection signal, Th1~Th3...threshold value, Lv...power line, Sr1~Sr3...reset signal

Claims

1. a single voltage detection element having a plurality of voltage detection terminals for inputting voltage of a power supply line through which power is supplied, and an abnormality detection signal output terminals for outputting an abnormality detection signal indicating whether or not there is an abnormality in the voltage of the power supply line, the number of the abnormality detection signal output terminals being the same as the number of the voltage detection terminals; when the voltage of the power supply line exceeds or falls below a threshold value previously set for each of the plurality of voltage detection terminals, the single voltage detection element switches between the presence or absence of an abnormality indicated by the abnormality detection signal output from the abnormality detection signal output terminal corresponding to the threshold value; a first voltage detection terminal and a second voltage detection terminal among the plurality of voltage detection terminals are connected to the same power supply line; In-vehicle power supply monitoring device.

2. a first threshold value corresponding to the first voltage detection terminal is set lower than a rated voltage of the power supply line; the second threshold value corresponding to the second voltage detection terminal is set higher than the rated voltage of the power supply line; The vehicle-mounted power supply monitoring device according to claim 1 .

3. The voltage detection terminals are three or more, a third threshold value corresponding to a third voltage detection terminal among the plurality of voltage detection terminals is set to a value higher than a rated voltage of the power supply line and different from the second threshold value; The on-board power supply monitoring device according to claim 2 .

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