JP4375102B2 - Auto levelizer for vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep operation of an auto-levelizer stable even when a system is in an unstable condition in the auto-levelizer for onboard equipment. <P>SOLUTION: A microcomputer 4 adjusts and controls the optical axis of a head lamp 1 based on a vehicle height value detected by a vehicle height sensor 3 during normal operation. When a voltage of electric power supplied to the microcomputer 4 through a microcomputer power supply circuit 10 is lower than a predetermined voltage, an adjustment section 7 puts a transistor 16 in an off state and a transistor 14 in an on state and sets a DC drive signal of a drive circuit 5 at 0 [V]. This allows the optical axis of the head lamp 1 to be adjusted and controlled to a reference position for the lowest beam. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to an auto levelizer for a vehicle that adjusts the position of an in-vehicle device based on a detected vehicle height value.

As this type of device, for example, Patent Document 1 discloses a vehicle auto-leveler. According to the vehicle auto-leveler disclosed in Patent Document 1, the detected vehicle height value is filtered to calculate the pitching angle, the pitching angle is corrected, and the corrected pitching angle is thresholded. The position of the in-vehicle device is determined by comparing with the value, and the position is adjusted. As a result, the vehicle height detection value is filtered, and the optical axis position of the headlamp (on-vehicle equipment) is adjusted according to the pitching angle while eliminating the influence of road surface unevenness.
JP 11-31442 A

  For example, in the case of an auto levelizer for headlamps, the operation is guaranteed during normal operation, but if an unstable state is caused in the system, such as when the operating power supply becomes low voltage or momentary interruption due to some influence, for example, There is also a possibility that the optical axis of the headlamp may face upward, and in this case, there is a risk that the view of the driver of the oncoming vehicle will be lost. Such a problem is present not only in the headlamp auto-leveler but also in all in-vehicle devices.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an auto levelizer for a vehicle that can keep the operation of the auto levelizer stable even when the system is in an unstable state. Is to provide.

According to invention of Claim 1, it acts as follows. That is, the control means operates by being supplied with power from the vehicle battery, and adjusts and controls the position of the in-vehicle device based on the vehicle height value detected during normal operation. At this time, the detecting means detects the power supply voltage supplied from the vehicle battery to the control means, but the adjusting means is on-vehicle equipment on condition that the power supply voltage detected by the detecting means is outside the predetermined voltage range. Since the position of the vehicle is adjusted to the reference position, the position of the vehicle-mounted device can be adjusted to the reference position even if a voltage that makes the operation of the control means unstable is applied, and the operation of the auto levelizer can be kept stable. become able to.
The detection means is configured by connecting a plurality of resistors and diodes in series, and detects the power supply voltage supplied to the control means by dividing the voltage with the plurality of resistors and diodes. The adjusting means includes a switching element having a control terminal connected to a common connection point of a plurality of resistors and diodes constituting the detecting means, and is switched by the divided voltage detected by the detecting means. By switching the element, the driving voltage of the in-vehicle device by the driving circuit is fixed to 0 V, and the position of the in-vehicle device is adjusted to the reference position. Thereby, when the power supply voltage supplied to the control means is outside the predetermined voltage range, the position of the in-vehicle device can be adjusted to the reference position, and the operation of the auto levelizer can be kept stable.

According to the second aspect of the present invention, the in-vehicle device is a headlamp, and the adjustment means adjusts the optical axis of the headlamp so as to keep it at the lowest position, so there is no possibility of depriving the driver of the oncoming vehicle of view .

According to invention of Claim 3, it acts as follows. First, the detection means includes a reference voltage generator, a plurality of pre-stage resistors configured in parallel to a plurality of resistors and diodes connected in series, and a plurality of pre-stage resistors of a power supply voltage supplied to the control means. And a comparator for comparing the divided voltage by the detector with the reference voltage generated by the reference voltage generator. The adjusting means switches the switching element on and off based on the comparison result of the comparator, thereby fixing the driving voltage of the in-vehicle device by the driving circuit to a predetermined value and adjusting the position of the in-vehicle device to the reference position. Even though a diode has a temperature characteristic and a circuit configuration including the diode makes the circuit configuration vulnerable to temperature fluctuations, a plurality of pre-stage resistors are configured in parallel with the plurality of resistors and the diode. A diode for comparing the divided voltage of the power supply voltage supplied to the control means by a plurality of pre-stage resistors and the reference voltage generated by the reference voltage generator by a comparator, and switching on and off the switching element according to the comparison result of the comparator It is possible to configure a circuit that eliminates the temperature characteristics of the circuit as much as possible.

According to the fourth aspect of the present invention, since the change mitigation means prevents a steep ON / OFF change of the switching element, the power supply voltage supplied to the control means follows the voltage of the vehicle battery at high speed and performs switching. Even if a suddenly changing voltage is applied to the control terminal of the element, the voltage change can be mitigated, the position of the in-vehicle device can be stably adjusted to the reference position, and the operation of the auto levelizer can be stabilized. Will be able to keep.
As in the fifth aspect of the invention, it is desirable that the change mitigating means is constituted by a capacitor.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to an auto levelizer for a headlamp for a vehicle will be described with reference to FIGS. 1 to 3.
FIG. 1 shows a schematic block diagram of an auto levelizer for a vehicle headlamp. The auto levelizer 2 of the headlamp 1 detects a vehicle height value accompanying road surface unevenness by a vehicle height sensor 3 and adjusts the position and angle of the optical axis of the headlamp 1 based on the vehicle height value.

  In FIG. 1, an auto levelizer 2 includes a microcomputer 4 (hereinafter referred to as a microcomputer) as a control means, a drive circuit 5, a vehicle height sensor 3, a power supply voltage detector 6 as a detection means, and an adjustment means. And an actuator 8, and adjusts the optical axis of the headlamp 1 based on the vehicle height value detected by the vehicle height sensor 3. Note that the vehicle height sensor 3 and the actuator 8 may or may not be included as components of the auto levelizer 2.

  The microcomputer 4 is supplied with power from a battery 9 mounted on the vehicle through a microcomputer power circuit 10 (control means power circuit). The microcomputer power supply circuit 10 stabilizes the power supply voltage of the battery 9 and supplies power to the microcomputer 4. In addition, the battery 9 is comprised by the power supply of 12V or 24V, for example, and the voltage fluctuation according to an external load is large.

  The drive circuit 5 includes a general D / A conversion unit (not shown) and an amplification circuit unit 11 (see FIG. 2B). The drive circuit 5 is configured to operate by being supplied with power from the battery 9, amplifies the DC signal output from the microcomputer 4 by the amplifier circuit unit 11, generates a DC drive signal, and supplies the DC drive signal to the actuator 8. It is like that. As shown in FIG. 2B, an example of a circuit using the operational amplifier circuit, the amplifier circuit unit 11 is configured by a positive phase amplifier including an operational amplifier 11a and resistors 11b and 11c. FIG. 2A shows an example of an operational amplifier circuit. The operational amplifier 11a is composed of a general PNP Darlington input operational amplifier (transistors Tr1 to Tr10, a resistor Ra, a phase compensation capacitor Ca, currents I1 to I5 from a current source), and detailed description of the circuit is omitted. However, the amplification factor of the amplifier circuit unit 11 is adjusted to 4, for example.

  When the DC drive signal generated by the drive circuit 5 is given to the actuator 8, the headlamp 1 (corresponding to the vehicle-mounted device of the present invention: a load) can be driven. With these configurations, during normal operation, the microcomputer 4 adjusts and controls the optical axis of the headlamp 1 through the actuator 8 by the drive circuit 5. The actuator 8 adjusts the optical axis of the headlamp 1 upward when a high voltage is applied, and downwards when the low voltage is applied. Note that the reference position of the optical axis of the headlamp 1 is, for example, downward.

  The power supply voltage detection unit 6 is configured to detect a power supply voltage supplied to the microcomputer 4, and specifically includes a circuit shown below. That is, as shown in FIG. 1, a resistor 12, a plurality (N stages, for example, two stages) of diodes D (forward direction), and a resistor 13 are connected between the output of the microcomputer power supply circuit 10 and the ground. ing. Further, a common connection point of the diode D and the resistor 13 is a detection terminal of the power supply voltage detection unit 6. In this manner, the power supply voltage detection unit 6 includes the resistor 12, the plurality of diodes D, and the resistor 13.

The adjustment unit 7 is provided to forcibly adjust the DC drive signal supplied from the drive circuit 5 to the actuator 8 to 0 V voltage on condition that the voltage detected by the power supply voltage detection unit 6 is not more than a predetermined voltage. It has been. Specifically, it is configured by the following circuit.
That is, as shown in FIG. 1, the collector-emitter of an NPN bipolar transistor 14 is connected between the common connection point of the drive circuit 5 and the actuator 8 and the ground. A resistor 15 and a collector-emitter of the bipolar transistor 16 are connected between the battery 9 and the ground. The base of the bipolar transistor 14 is connected to a common connection point between the resistor 15 and the collector of the bipolar transistor 16. A base of an NPN bipolar transistor 16 is connected to a detection terminal of the power supply voltage detection unit 6. In this way, the adjusting unit 7 is configured by the resistor 15 and the bipolar transistors 14 and 16.

The operation of the above configuration will be described with reference to FIG.
By the way, a so-called bypass capacitor (not shown) is attached to the power supply terminal of the microcomputer 4, and the power supply generated by the microcomputer power supply circuit 10 is reduced by mitigating sudden changes in power supply noise and the voltage applied from the battery 9. The voltage is supplied as the power supply voltage of the microcomputer 4.

In the following description, the DC drive signal applied to the actuator 8 when the power supply voltage (microcomputer power supply voltage) applied to the microcomputer 4 at the rise of the voltage of the battery 9 follows the voltage change of the battery 9 at a low speed. Explain how the level changes.
As shown in FIG. 3, when the voltage Vs of the battery 9 rises, the voltage Vm of the microcomputer power supply circuit 10 gradually increases following this voltage. When the voltage Vm of the microcomputer power supply circuit 10 is low, the base voltage of the transistor 16 is also low and the transistor 16 is turned off. Therefore, a current flows from the battery 9 to the base of the transistor 14 through the resistor 15, the transistor 14 is turned on, and the output of the drive circuit 5 is fixed to approximately 0 [V].

  At this time, the case where the power supply voltage detection part 6 and the adjustment part 7 are not provided is demonstrated as a prior art structural example. In this case, the output voltage Vm of the microcomputer power supply circuit 10 gradually increases, and a high voltage is applied to the actuator 8 through the drive circuit 5 even when the microcomputer 4 is in an unstable operation state. At this time, as shown in FIG. 3, since the drive circuit 5 is supplied with the power supply voltage from the battery 9, the transistor Tr7 in the output stage of the operational amplifier 11a constituting the drive circuit 5 cannot be driven (INP input voltage +2 When × VF + current I2 transistor saturation voltage> battery voltage), the battery voltage is applied to the actuator 8 from the output stage of the operational amplifier 11a through the resistors 11b and 11c (see current I3 in FIG. 2A). ). When the battery voltage is applied to the actuator 8, the optical axis of the headlamp 1 is adjusted to be high.

  In this embodiment, since the power supply voltage detection unit 6 and the adjustment unit 7 are provided, the drive circuit 5 can be used even when the voltage output from the microcomputer power supply circuit 10 is low and the operation of the microcomputer 4 is unstable. The DC drive signal output from can be maintained at approximately 0 [V]. Thereafter, as shown in FIG. 3, the voltage output from the microcomputer power supply circuit 10 rises, but the resistance values of the resistors 12 and 13 are set to R1 and R2, respectively, and the forward voltage of the diode D is set to VF. In this case, when the voltage reaches (1 + N + R1 / R2) × VF, the transistor 16 is turned on and the transistor 14 is turned off. Therefore, when the power supply voltage applied to the microcomputer 4 rises and the microcomputer 4 operates stably, the output voltage of the drive circuit 5 is applied to the actuator 8 and shifts to the normal operation state. The microcomputer 4 can adjust and control the optical axis of the headlamp 1 via the actuator 8 based on the vehicle height value detected by the vehicle height sensor 3.

  According to the first embodiment, the microcomputer 4 adjusts and controls the optical axis of the headlamp 1 based on the vehicle height value detected by the vehicle height sensor 3 during normal operation. 9 constantly detects the power supply voltage supplied to the microcomputer 4 through the microcomputer power supply circuit 10. For example, the voltage detected by the power supply voltage detection unit 6 at the rise of the voltage of the battery 9 or the output voltage of the microcomputer power supply circuit 10 is detected. When the voltage is lower than the predetermined voltage (1 + N + R1 / R2) × VF, the transistor 14 is turned off to turn on the transistor 14 of the adjusting unit 7 and the transistor 14 draws all the drive current of the drive circuit 5. Even if the drive circuit 5 outputs a high voltage when the is in an unstable operation state The optical axis of the headlamp 1 will be able to adjust the control on the top downwards of the reference position, it is possible to maintain the operation of the automatic levelizer 2 stably.

(Second Embodiment)
4 and 5 show a second embodiment of the present invention. The difference from the first embodiment is that the influence of the forward voltage VF temperature characteristic of the diode D of the power supply voltage detector 6 is considered. Even when the temperature changes, the position of the headlamp 1 (on-vehicle equipment) can be stably adjusted to the lowest position (reference position) when the power supply voltage applied to the microcomputer 4 is below a predetermined voltage. is there. The same parts as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts will be described below.

In the case of the in-vehicle device described in the first embodiment, it is necessary to obtain stable characteristics within a temperature range of, for example, −40 [° C.] to 140 [° C.]. In the case of the circuit configuration described in the first embodiment, when the temperature changes, the interval at which the DC drive signal is fixed at 0 [V] varies due to the influence of the VF temperature characteristic of the diode D, and a constant characteristic can be obtained. become unable.
Therefore, it is desirable to configure the power supply voltage detection unit 20 as shown in FIG. 4 instead of the power supply voltage detection unit 6. That is, as shown in FIG. 4, in addition to the configuration described in the first embodiment, the power supply voltage detector 20 includes a plurality of resistors 21 and 22, a comparator 23, a reference voltage generator 24, a resistor And an NPN-type bipolar transistor 26.

The plurality of resistors 21 and 22 divide the power supply voltage supplied to the microcomputer 4, and this divided voltage is applied to the inverting input terminal of the comparator 23.
The reference voltage generator 24 is configured by a voltage generator having high-accuracy temperature characteristics (highly stable with respect to temperature) by, for example, a band gap voltage reference or the like. It has come to be given.

The comparator 23 is configured using the battery 9 voltage as a drive power supply, and its output terminal is connected to the base of the transistor 26 via the resistor 25.
The collector of the transistor 26 is connected to the base of the transistor 16, and the emitter of the transistor 26 is connected to the ground. In this way, the power supply voltage detection unit 20 is configured.

  In this case, as schematically shown in FIG. 5, when the resistance value of the resistor 21 is R3 and the resistance value of the resistor 22 is R4, the power supply voltage applied to the microcomputer 4 is (1 + R3 / R4) × ( When the voltage is equal to or lower than the voltage of the reference voltage of the reference voltage generator 24, the DC drive signal is fixed to approximately 0 [V]. Therefore, according to the configuration of the present embodiment, the voltage can be set without depending on the temperature characteristics of the forward voltage VF of the diode D. Therefore, even if the power supply voltage supplied to the microcomputer 4 becomes unstable, the power supply The threshold voltage of the voltage can be set with higher accuracy.

(Third embodiment)
6 and 7 show a third embodiment of the present invention. The difference from the second embodiment is that the power supply voltage applied to the microcomputer 4 follows the voltage of the battery 9 at high speed. Even in such a case, the optical axis of the headlamp (on-vehicle equipment) can be stably adjusted to the lowest position (reference position). The same parts as those of the second embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts will be described below.

For example, in a power supply circuit using a high-speed type operational amplifier, the power supply voltage supplied to the microcomputer 4 follows the voltage of the battery 9 at high speed. In this case, it is desirable to configure as shown in FIG.
That is, it is preferable that the capacitor 30 is provided between the base and the emitter of the transistor 16 as a change relaxation means. At this time, as shown in FIG. 7, the operation of the base voltage of the transistor 16 is moderated even if the microcomputer power supply voltage Vm changes so as to follow the battery voltage Vs at high speed. Further, the ON / OFF change of the transistor 16 is alleviated, and a stable period of 0 [V] can be obtained, and the same effect as in the second embodiment can be obtained.

(Other embodiments)
The present invention is not limited to the above embodiment, and for example, the following modifications or expansions are possible.
Although the embodiment using the bipolar transistors 14, 16, and 26 is shown, any element (for example, FET) may be used as long as it functions as a switching element.

  Although the embodiment has been described in which the position of the optical axis is forcibly adjusted downward on condition that the power supply voltage detected by the power supply voltage detection units 6 and 20 is equal to or lower than a predetermined voltage, this is shown in FIG. , 20 may be adjusted downward so that the position of the optical axis of the headlamp 1 is adjusted on condition that the power supply voltage detected at 20 is equal to or higher than a predetermined voltage. That is, the circuit may be configured so that the position of the optical axis of the headlamp 1 is adjusted downward on the condition that the voltage range is outside the predetermined voltage range.

  Although the embodiment for adjusting the optical axis of the headlamp 1 has been described, the present invention may be applied to any in-vehicle device as long as the position of the in-vehicle device is adjusted.

1 is a schematic electrical configuration diagram showing a first embodiment of the present invention. (A) and (b) are diagrams showing a part of a drive circuit. The figure which shows the relationship of the voltage change of the battery for vehicles, the power supply voltage for microcomputers, and a DC drive signal FIG. 1 equivalent diagram showing a second embodiment of the present invention 3 equivalent figure FIG. 1 equivalent view showing a third embodiment of the present invention 3 equivalent figure

Explanation of symbols

In the drawings, 1 is a headlamp (on-vehicle equipment), 2 is a vehicle auto-leveler, 4 is a microcomputer (control means), 5 is a drive circuit, 7 is an adjustment unit (adjustment means), and 9 is a battery (vehicle battery). , 12, 13, 15 and 25 are resistors, 21 and 22 are resistors (previous resistors), 6 and 20 are power supply voltage detectors (detection means), 14 and 26 are bipolar transistors, and 16 is a bipolar transistor (switching). Element), 23 is a comparator, 24 is a reference voltage generator, 30 is a capacitor (change mitigation means), and D is a diode.

Claims (5)

An auto levelizer for a vehicle that adjusts the position of an in-vehicle device based on a vehicle height value detected by a vehicle height sensor ,
Control means that operates by being supplied with power from the vehicle battery and adjusts and controls the position of the in-vehicle device based on the vehicle height value detected during normal operation;
A drive circuit for driving the in-vehicle device based on the control of the control means;
A plurality of resistors and diodes are connected in series, and are supplied to the control means by detecting a divided voltage divided by the plurality of resistors and the diodes from the voltage of the vehicle battery. Detecting means for detecting the power supply voltage;
Adjusting means for adjusting the position of the in-vehicle device to the reference position on condition that the power supply voltage detected by the detecting means is outside the predetermined voltage range ;
The adjustment means includes a switching element having a control terminal connected to a common connection point of a plurality of resistors and diodes constituting the detection means, and when the divided voltage detected by the detection means falls below a predetermined voltage A vehicle auto-leveler characterized in that by switching the switching element, the drive voltage of the in-vehicle device by the drive circuit is fixed at 0 V and the position of the in-vehicle device is adjusted to a reference position . The in-vehicle device is a headlamp,
2. The vehicle auto leveler according to claim 1 , wherein the adjusting means adjusts the optical axis of the headlamp so as to keep the optical axis downward . The detection means includes
A reference voltage generator;
A plurality of pre-stage resistors configured in parallel with the plurality of resistors and diodes connected in series;
A comparator for comparing a divided voltage of a plurality of previous-stage resistors of a power supply voltage supplied to the control means and a reference voltage generated by the reference voltage generator;
The adjusting means switches the switching element according to a comparison result of the comparator, thereby fixing a driving voltage of the in-vehicle device by the driving circuit to 0 V and adjusting a position of the in-vehicle device to a reference position. Item 3. The vehicle auto-leveler according to Item 1 or 2. 4. The vehicle auto leveler according to claim 1 , further comprising a change mitigating unit that prevents a steep ON / OFF change of the switching element . 5. 5. The vehicle auto leveler according to claim 4 , wherein the change mitigation means is constituted by a capacitor .

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