JP2007168715A - Operation control device for automobile electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable voltage monitoring for detecting an abnormal condition on a ground side of a load, and to prevent the generation of dark current attendant on the load abnormal condition detection in an ignition-off state, in an operation control device for automobile electric equipment capable of receiving electricity from an on-vehicle power supply even in the ignition-off state. <P>SOLUTION: A voltage detecting current intercepting mechanism 2 intercepting input of a voltage detecting current to a load abnormality detecting circuit 6 when an ignition switch 121 turns into an off state, is provided. Therefore, when the ignition switch 121 is turned off, the dark current does not flow in the load abnormality detecting circuit 6, so that drain of the on-vehicle power supply 9 during engine stop can be suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an operation control apparatus for an automotive electronic device.

JP-A-11-170986 JP 7-39066 A

  Various electronic devices are mounted on vehicles such as automobiles. Among these electronic devices, those that have a significant impact on running due to malfunctions are equipped with circuits that detect load abnormalities such as drive path disconnection (open) abnormality, ground short circuit, or power supply short circuit. Abnormality monitoring is performed based on this. Examples of the load abnormality detection target include a defogger (Patent Document 1) used for anti-fogging of the rear window, an air-conditioning blower on the rear window side, and the like. There are various methods for detecting a load abnormality. As a simple method, there is a method for detecting a voltage fluctuation at a voltage detection point formed on the ground side of a load using a resistance voltage dividing circuit or the like (Patent Document 2). ).

  Incidentally, some of the above electronic devices are configured to be able to receive power from the on-vehicle power source (battery) even when the ignition switch is turned off. For example, the defogger described above melts frost frozen on the window glass, and the rear diff relay that opens and closes the energization path can operate even when the ignition switch is off.

  As described above, when it is attempted to detect such a load abnormality of an electronic device by monitoring the voltage on the ground side, the load energization path is interrupted (for example, in the case of a rear differential relay, the operation of the defogger Even when the switch is off), the voltage detection current for detecting the load abnormality is not cut off and continues to flow as a dark current, and there is a problem that the battery is likely to be consumed.

  An object of the present invention is to provide an electronic device operation control device that can receive power from an on-vehicle power source even when the ignition is off, while enabling voltage monitoring for abnormality detection on the ground side of the load, and detecting the load abnormality when the ignition is off. The purpose of this is to prevent the generation of dark current.

Means for Solving the Problems and Effects of the Invention

The present invention relates to an operation control device for an automotive electronic device having a load configured to be able to receive power from a vehicle-mounted power supply even when the ignition switch is turned off.
A drive switch that is provided on the ground side of the drive line of the load and switches the energization state of the load between a conduction state and a cutoff state;
At the voltage detection point formed between the drive switch and the load, it is provided by branching from the drive line to the ground side.If an abnormality occurs in the drive line between the load and the voltage detection point, the abnormality is detected. A load abnormality detection circuit that outputs the reflected signal as a voltage detection signal at a voltage detection point; and
A drive control unit that performs switching control of the drive switch and holds the drive switch in a shut-off state when the ignition switch of the automobile is turned off,
And a voltage detection current cutoff mechanism that cuts off the input of the voltage detection current to the load abnormality detection circuit when the ignition switch is turned off.

  The object of application of the present invention is an electronic device for automobile in which the load can be received from an in-vehicle power supply even when the ignition switch is turned off. On the ground side of the drive line of the load, there is a drive switch that switches the energization state between the load between the conductive state and the cut-off state, and this drive switch is cut-off even when the ignition switch is off. Then, the load drive current does not flow. However, if a load abnormality detection circuit is provided at a voltage detection point formed between the drive switch and the load so as to branch from the drive line to the ground side, the load abnormality detection circuit includes a drive switch. The voltage detection current flows regardless of conduction / interruption.

  Therefore, in the present invention, when the ignition switch is turned off, a voltage detection current cutoff mechanism that cuts off the input of the voltage detection current to the load abnormality detection circuit is provided. Therefore, when the ignition switch is turned off, the load abnormality detection circuit is provided. Thus, no dark current flows, and consumption of the in-vehicle power source when the engine is stopped can be suppressed.

  Abnormalities occurring in the load drive line include, for example, open (disconnection) abnormality, ground short circuit abnormality (hereinafter also referred to as “ground fault”), and power supply short circuit abnormality (hereinafter also referred to as “sky fault”). Under normal conditions, when the drive switch is cut off, a divided voltage corresponding to the load resistance and the specific resistance of the load abnormality detection circuit appears at the voltage detection point. However, when a ground fault occurs in the drive line, a detection voltage lower than that at the normal time appears at the voltage detection point, so that an abnormality can be detected. On the other hand, when the drive switch is in a conductive state, under normal conditions, a voltage lower than that at the time of interruption by a voltage drop due to the load resistance appears at the voltage detection point. However, when a power fault has occurred, a voltage higher than the normal voltage appears by the amount not passing through the load resistance, so that an abnormality can be detected.

  On the other hand, when an open abnormality occurs in the drive line of the load, the voltage at the voltage detection point is often in an unstable state, which may cause a problem in stable abnormality detection. Therefore, if an in-vehicle power source is directly connected to the voltage detection point via a pull-up resistor, the above open abnormality can be reliably detected. In this case, a new voltage detection current path that bypasses the load is generated via the pull-up resistor. However, in the present invention, the above-described voltage detection current cutoff mechanism is adopted, so that the darkness when the engine is stopped is used. It does not lead to an increase in current.

  The load abnormality detection circuit can be, for example, a resistance voltage dividing circuit inserted between the voltage detection point and the ground. A voltage detection signal is output as a divided voltage of the resistance voltage dividing circuit. Further, in the present invention, the type of the on-vehicle electronic device and thus the load is not limited. For example, as a specific example of the load, a relay used for energization control of the rear window anti-fogging device can be used. The relay is used to open and close the movable iron pieces that make up the switch by energizing the inductor. The DC resistance component of the inductor itself is small and the dark current is likely to increase (especially, the load abnormality detection circuit is divided into resistors). In the case of a circuit, the dark current value is determined by the series resistance value of the resistance voltage dividing circuit, and the current reduction effect due to the series resistance of the load is hardly expected). Therefore, it can be said that application of the present invention is particularly effective.

  The voltage detection current cut-off mechanism can be configured to have a detection current cut-off transistor switch provided on a branch path from the drive line of the load abnormality detection circuit. The function to shut off the load abnormality detection circuit can be realized with low power consumption. In this case, when the ignition switch is off, the detection current cut-off transistor switch is turned off when the voltage input from the in-vehicle power supply is cut off (that is, the transistor that shifts to the cut-off state: an NPN-type bipolar transistor or an N channel) If a FET of the type is used, it is not necessary to secure a power supply voltage when the detection current cut-off transistor switch is driven off.

  Specifically, a drive voltage input line for inputting a drive voltage from the in-vehicle power source to the detection current cutoff transistor switch via the power switch can be provided. The drive control unit can turn off the power switch on the drive voltage input line when the ignition switch is turned off. According to this configuration, when the ignition switch is turned off, the detection current cut-off transistor switch is cut off in conjunction with the power switch, and the dark current derived from the detection current can be reliably reduced.

  In this case, the drive input terminal of the detection current cutoff transistor switch is connected to the drive line, and the sub-transistor switch can be provided on the switch control line extending from the drive terminal to the ground. By switching the conduction / cutoff of the sub-transistor switch, the drive voltage of the detection current cut-off transistor switch (hereinafter also referred to as a main transistor switch) can be switched between the ground level and the voltage level of the drive line. According to this structure, by switching the conduction / cutoff of the sub-transistor switch, the main transistor switch can be cut off via the sub-transistor switch regardless of the conduction state of the drive switch, and the detection current can be cut off reliably. . The sub-transistor switch has, for example, a configuration in which conduction / cutoff is switched by a driving voltage input line that inputs a driving voltage via the power switch described above (that is, a configuration in which the driving voltage input line is connected to a driving terminal of the sub-transistor switch) By doing so, the main transistor switch can be reliably turned off when the ignition switch is turned off.

  When the load abnormality detection circuit is configured as a resistance voltage dividing circuit, a detection current cutoff transistor switch can be inserted between the resistance voltage dividing circuit and the drive line. In this way, it is possible to drive the detection current cut-off transistor switch without greatly affecting the output voltage level of the resistance voltage dividing circuit. As a result, the ignition failure detection algorithm is not accompanied by a major design change. A dark current reduction function when the switch is off can be added.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram illustrating an example of an operation control device 1 for an automotive electronic device to which the present invention is applied. In this embodiment, as an automobile electronic device to be controlled, a rear window anti-fogging device is taken as an example (however, other electronic devices that can be driven even when the ignition switch 121 is off, such as a headlamp). May be). As shown in FIG. 2, the target drive unit 108 heats the rear window glass with an embedded heating wire to evaporate condensation or melt frost, or on the inner surface of the rear window. A rear blower motor 182 or the like that ejects an air-conditioned air flow along the same, and a switch 72 on the drive energization path 109 is incorporated in the relay 7. The relay 7 controls the operation of the electronic machine by opening and closing the movable iron piece constituting the switch 72 by energizing the inductor 71. The in-vehicle power source 9 is directly connected to the relay 7 (more specifically, the inductor 71 included in the relay 7), and power can be received from the in-vehicle power source 9 even when the ignition switch 121 is turned off. (Hereinafter also referred to as load 7).

  A drive switch 5 is provided on the ground side of the drive line 8 of the load 7 to switch the energization state of the load 7 between a conduction state and a cutoff state. Then, at the voltage detection point D formed between the drive switch 5 and the load 7, an abnormality occurs in the drive line 8 between the load 7 and the voltage detection point D in a form that branches from the drive line 8 to the ground side. A load abnormality detection circuit 6 is provided that outputs a signal reflecting the abnormality as a voltage detection signal SD at the voltage detection point D when it occurs.

  The drive control unit 4 performs switching control of the drive switch 5. The drive control unit 4 holds the drive switch 5 in the shut-off state when the ignition switch 121 of the automobile is turned off. In the present invention, the voltage detection current cutoff mechanism 2 is provided that cuts off the input of the voltage detection current to the load abnormality detection circuit 6 when the ignition switch 121 is turned off. When the ignition switch 121 is turned off, the input of the voltage detection current to the load abnormality detection circuit 6 is interrupted by the voltage detection current interruption mechanism 2, so that the engine is stopped due to the dark current to the load abnormality detection circuit 6. The consumption of the in-vehicle power supply 9 can be suppressed.

The on-vehicle power source 9 is a battery composed of a lead storage battery or the like, and the output voltage thereof is a battery voltage + V _B (the nominal voltage is, for example, +12 V, but varies depending on the load usage status and the alternator operating status). The voltage of the "vehicle electrical" in the present invention is a general term for all voltage derived from the battery voltage + V _B, stable stabilized for example the battery voltage + V _B by a regulator (known voltage stabilizer) The power supply voltage (here, signal system power supply voltage + V _CC (for example, +5 V)) is also considered to belong to the broad concept of in-vehicle power supply voltage.

Both the battery voltage + V _B and the stabilized power supply voltage + V _CC are directly connected to the power supply without switching between the power supply switches 31 and 33 and the supply line that can be switched between the output permissible / shutdown states by the power switches 31 and 33. Two types of supply lines are provided. In order to clarify whether switch control is possible, the power output (switched power output) via the power switches 31 to 33 is described as + V _B ^S and + V _CC ^S, and the power output not via the power switches 31 to 33 ( Non-switched power output) is described as + V _B ^U and + V _CC ^U.

  The load abnormality detection circuit 6 is a resistance voltage dividing circuit 62A, 62B inserted between the voltage detection point D and the ground, and a voltage detection signal SD is output as a divided voltage of the resistance voltage dividing circuit 62A, 62B. The The on-vehicle power supply 9 is directly connected to the voltage detection point D via a pull-up resistor 61.

  The drive control unit 4 includes a CPU 41, a ROM 42 (which stores a main control program for controlling the operation of the drive switch 5 and a load abnormality monitoring program), a RAM 43 (which is an execution memory for these programs), and an input / output unit 44. Are configured as a microcomputer (ECU) connected by an internal bus, and the control signals SS1 and SS2 of the power switches 31 and 33 and the control signal SS3 of the drive switch 5 are output from the input / output unit 44. The voltage detection signal SD from the load abnormality detection circuit 6 (resistance voltage dividing circuits 62A and 62B) is input to the A / D conversion port of the input / output unit 44.

  The drive control unit 4 is connected to a communication bus (here, a serial communication bus) 47 via a communication interface 45 (reference numeral 46 is a communication buffer memory). On the other hand, the on / off signal of the ignition switch 121 is input to another ECU 120 to acquire what is transmitted from the ECU 120 via the communication bus 47. When the signal IG indicates that the ignition switch 121 is on, the power switches 31 and 33 are turned on. On the other hand, when the signal IG indicates that the ignition switch 121 is in an off state, the power switches 31 and 33 are turned off (shut off state). Further, when the operation switch 130 (for example, the defogger drive switch) of the load 7 is turned on, the control signal SS3 for driving the load 7 (for switching the drive switch 5 to the conductive state) is output. The drive switch 5 shows only the main transistor 51 provided on the drive line of the relay 7 in the drawing, but an auxiliary transistor (not shown) for signal input is provided on the preceding stage side, and the auxiliary transistor is a control signal. Directly driven by SS3.

  The load abnormality monitoring program detects various abnormalities occurring in the load based on the voltage detection signal SD, for example, according to the flow shown in FIG. The abnormality monitoring program is executed, for example, by periodically interrupting the processing task of the main control program for monitoring the operation status of the operation switch 130 and controlling the operation of the drive switch 5 according to the operation status. First, in S1, the drive switch 5 is turned off. Under normal conditions, when the drive switch 51 is in the cut-off state, a divided voltage corresponding to the load resistance and the specific resistance of the load abnormality detection circuit appears at the voltage detection point. In S2, this determination is made by comparing the first threshold voltage V1 with the instruction voltage of the voltage detection signal SD. If the voltage is higher than the first threshold voltage V1, the process proceeds to S3 and the drive switch 51 is turned on. When the drive switch 51 is in a conductive state, the voltage detection signal SD indicates a voltage lower than that when the drive switch 51 is cut off by a voltage drop caused by the load resistance. In S4, this determination is made by comparing the second threshold voltage V2 with the instruction voltage of the voltage detection signal SD. If the voltage is lower than the second threshold voltage V2, the process proceeds to S5, the load is determined to be normal, and the abnormality detection process is terminated. On the other hand, when the load or its terminal is short-circuited (power fault), a voltage higher than that at normal time appears as much as it does not go through the load resistance. That is, in S4, if a voltage higher than the second threshold voltage V2 is indicated, the process proceeds to S9, and it is determined that the power supply is short-circuited at the load or its terminal, and the process proceeds to S10.

  On the other hand, if the instruction voltage of the voltage detection signal SD is lower than the first threshold voltage V1 in S2, it is determined that an abnormality has occurred and the process proceeds to S6. In this case, there are two types of abnormalities occurring: ground short circuit (ground fault) of load output and disconnection (open). When a ground fault occurs in the drive line 8, the indicated voltage of the voltage detection signal SD indicates a low value of the ground level. On the other hand, in the case of an open abnormality, a voltage level higher than that at the time of the ground fault is shown by the voltage dividing ratio between the combined resistance of the resistance voltage dividing circuit and the pull-up resistor 61. In S6, this determination is performed by comparing the third threshold voltage V3 with the instruction voltage of the voltage detection signal SD. If a voltage lower than the third threshold voltage V3 is indicated, the process proceeds to S8, it is determined that there is a ground fault of the load, and the process proceeds to the abnormality handling process of S10. On the other hand, if the voltage is higher than the third threshold voltage V3, the process proceeds to S7, where it is determined that the load is abnormally opened, and the process proceeds to the abnormality handling process of S10. In the abnormality handling process of S10, the type of load abnormality that has occurred is recorded together with the detection date and time of the load abnormality, for example, so-called diagnostic storage processing, and warning information indicating the occurrence of abnormality is output by one or both of audio and visual display, etc. A warning notification process is performed.

  Specifically, a drive voltage input line 11 for inputting a drive voltage from the in-vehicle power source 9 to the detection current cutoff transistor switch 21 via the power switch 31 can be provided. The drive control unit 4 can turn off the power switch 31 on the drive voltage input line 11 when the ignition switch 121 is turned off. According to this configuration, when the ignition switch 121 is turned off, the detection current cut-off transistor switch 21 is cut off in conjunction with the power switch 31 to reliably reduce the dark current derived from the detection current. it can.

  Returning to FIG. 1, the drive input terminal of the detection current cutoff transistor switch 21 (here, the gate of the P-channel MOS-FET: the base when the transistor switch 21 is formed of a bipolar transistor (for example, PNP type)) is Are connected to the drive line 8 via a pull-up resistor 22. A sub-transistor switch 23 (here, a bipolar transistor (NPN type)) is provided on the switch control line 12 from the connection point of the drive terminal and the pull-up resistor 22 to the ground.

The sub-transistor switch 23 is configured to switch between conduction / cut-off by the drive voltage input line 11 that inputs the drive voltage + V _B ^S via the power switch 31, that is, the drive voltage input line 11 is connected to the drive terminal of the sub-transistor switch 23. It has been configured. When the ignition switch 121 is turned off, the power switch 31 is turned off (cut off), the sub-transistor switch 23 is also turned off, and the main transistor switch 21 is cut off. As a result, when the ignition switch 121 is off, that is, when the engine is stopped, the detection current on the branch path 10 provided with the load abnormality detection circuit 6 (resistance voltage dividing circuits 62A and 62B) is cut off, and dark current is reduced. Contribute to. The stabilized power supply voltage + V _CC ^S may be input to the drive voltage input line 11 via the power switch 33.

  In the circuit configuration of FIG. 1, the main transistor switch 21 is inserted between the resistance voltage dividing circuits 62A and 62B and the drive line 8, but as shown in FIG. It can also be inserted between 62B and ground. However, in order for the (P-channel type) main transistor switch 21 to become conductive when the sub-transistor 23 becomes conductive, the gate voltage needs to be negative when viewed from the drain side. It is necessary to add a resistor 62C that gives a negative voltage difference between the gate / drain between the gate and the drain. In this case, in addition to the increase in the number of parts due to the addition of the resistor 62C, the resistance voltage dividing ratio at the voltage output point S changes, and the voltage threshold for abnormality determination must be changed corresponding to the addition of the main transistor switch 21 A problem that does not occur. However, by inserting the main transistor switch 21 between the drive line 8 and the resistance voltage dividing circuits 62A and 62B as shown in FIG. 1, all the above problems are solved.

  The on / off state of the ignition switch can be determined on the side of the drive control unit 4, so that the operation of the detection current cut-off transistor switch 21 is controlled by a control signal SS4 from the drive control unit 4 side as shown in FIG. You may make it control. Here, the external control signal SS4 is input to the drive terminal (base) of the sub-transistor 23.

The circuit diagram which shows the 1st example of the operation control apparatus of the electronic device for motor vehicles based on this invention. The schematic diagram which shows the specific structural example of the electronic device for motor vehicles. The flowchart which shows an example of an abnormality detection process. The circuit diagram which shows the 2nd example of the operation control apparatus of the electronic device for motor vehicles based on this invention. The circuit diagram which shows the 3rd example of the operation control apparatus of the electronic device for motor vehicles based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Operation control apparatus of the electronic device for motor vehicles 2 Voltage detection electric current interruption mechanism 4 Drive control part 5 Drive switch 6 Load abnormality detection circuit 7 Load 8 Drive line 9 In-vehicle power supply 11 Drive voltage input line 12 Switch control line D Voltage detection point SD voltage Detection signal 21 Detection current cut-off transistor switch 22 Pull-up resistor 23 Sub-transistor switch 31 Power switch 61 Pull-up resistor 62A, 62B Resistance voltage divider 121 Ignition switch

Claims (7)

An operation control device for an automotive electronic device having a load configured to be able to receive power from a vehicle-mounted power supply even when the ignition switch is turned off,
A drive switch that is provided on the ground side of the drive line of the load, and switches an energization state of the load between a conduction state and a cutoff state;
A voltage detection point formed between the drive switch and the load is provided to branch from the drive line to the ground side, and an abnormality occurs in the drive line between the load and the voltage detection point. A load abnormality detection circuit that outputs a signal reflecting the abnormality as a voltage detection signal of the voltage detection point,
A drive control unit that performs switching control of the drive switch, and holds the drive switch in a shut-off state when the ignition switch of the automobile is turned off.
A voltage detection current cutoff mechanism that cuts off an input of a voltage detection current to the load abnormality detection circuit when the ignition switch is turned off;
An operation control device for an automotive electronic device, comprising:   2. The operation control apparatus for an automotive electronic device according to claim 1, wherein the on-vehicle power source is directly connected to the voltage detection point via a pull-up resistor.   The operation control device for an automotive electronic device according to claim 1, wherein the load is a relay used for energization control of a rear window anti-fogging device.   The automobile according to any one of claims 1 to 3, wherein the voltage detection current cutoff mechanism includes a detection current cutoff transistor switch provided on a branch path from the drive line of the load abnormality detection circuit. Operation control device for electronic equipment. A drive voltage input line for inputting a drive voltage from the in-vehicle power source to the detection current cutoff transistor switch via a power switch is provided,
5. The operation control device for an automotive electronic device according to claim 4, wherein when the ignition switch is turned off, the drive control unit turns off the power switch on the drive voltage input line. 6.   A drive input terminal of the detection current cut-off transistor switch is connected to the drive line, and a sub-transistor switch is provided on a switch control line extending from the drive input terminal to the ground. 6. The automotive electronic device according to claim 1, wherein the drive voltage of the detection current cut-off transistor switch is switched between a ground level and a voltage level of the drive line by cut-off switching. 7. Actuation control device.   The operation control device for an automotive electronic device according to claim 6, comprising the requirement according to claim 5, wherein the drive voltage input line is connected to a drive terminal of the sub-transistor switch.

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