JPH028932B2 - - Google Patents

Abstract

PURPOSE:To prevent the hunting of a drive motor by constituting such that at least one of two comparators for comparing between a light axis setting signal and a light axis detection signal will produce a detection signal only when the differential signal will exceed over the predetermined level. CONSTITUTION:In the first voltage comparator COM1, a light axis setting section VR1 and a light axis detecting section VR3 are connected directly while the second voltage comparator COM2 is connected through a resistor R2 to VR1 or VR3, where the first voltage comparator COM1 will receive the voltage applied on an inverted input terminal at the non-inverted input terminal while receive the other voltage at the inverted input terminal. Furthermore feedback circuits D1, D2 are connected between the input connected with a resistor R2 of COM2 and the output terminal, where the resistance of D1, D2 are made different when the voltage at the input terminal of COM2 is higher or lower than that at the output terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical axis adjustment device for a vehicle headlamp,
In particular, even if the amount of rotation due to the inertia of the drive motor that rotates forward and backward to move the optical axis of the headlight in the vertical direction varies depending on the direction of rotation, the optical axis of the headlight can be accurately directed to the set angle. The object of the present invention is to provide a novel optical axis adjustment device for a vehicle headlamp that can operate stably without causing hunting or the like.

As an optical axis adjustment device that adjusts the angle of the optical axis of the headlight of a vehicle, especially an automobile, the headlight is adjusted by the output of the optical axis detection section that detects the angle of the optical axis of the headlight and the operation of a knob, etc. The optical axis of the headlight is moved up and down by a drive motor that rotates forward and backward depending on the positive or negative sign of the difference after determining the difference between the output from the optical axis setting unit that sets the angle of the optical axis. There is. In such devices, the drive motor is controlled so that when there is a difference between the output of the optical axis detection section and the output of the optical axis setting section, the motor is rotated in a direction such that the difference becomes 0. When the magnitude of the output of the optical axis setting section is changed, the optical axis of the headlight is moved by the drive motor so that the output of the optical axis detection section becomes the same magnitude. The optical axis tends to be at an angle corresponding to the magnitude of the output of the optical axis setting section. However, in general, the drive motor that attempts to direct the optical axis of the headlight at a set angle rotates too much due to its inertia, then rotates in the opposite direction to the direction of rotation, causing the rotation to go too far. As a result, hunting occurs, in which the headlight moves up and down with a certain amplitude, and there is a risk that the operation may become unstable. Therefore, attempts have been made to stabilize the operation by stopping the drive motor when the absolute value of the difference between the output of the optical axis setting section and the output of the optical axis detection section is within a certain range. . In this case, if the range of the absolute value of the difference between the two outputs (stop area) where the drive motor is stopped is too narrow, the effect of providing the stop area cannot be obtained sufficiently. On the other hand, if the stop range is too wide, it is possible to stabilize the operation, but the angle of the optical axis of the headlight cannot be accurately controlled to the set angle. become unable to do so. Therefore, it can be said that the width of the stop area needs to be set to a width corresponding to the amount of rotation from when the difference between the two outputs of the drive motor becomes 0 until it stops.

Incidentally, the amount of rotation due to inertia of the drive motor that rotates forward and backward to move the optical axis of the headlamp in the vertical direction often differs depending on the rotation direction of the drive motor. In other words, it depends on the optical axis adjustment mechanism of the headlight, but for example, when the drive motor tries to tilt the headlight upward, the load applied to the drive motor is equal to the moment due to the headlight's gravity. In contrast, when the drive motor tries to tilt the headlight downward, the load applied to the drive motor is reduced by the moment due to the gravity of the headlight. When the drive motor tilts the headlight upward, the amount of rotation of the drive motor due to inertia is smaller than when the drive motor tilts the headlight upward. In such a case, if the width of the above-mentioned stop area is set to a width corresponding to the amount of rotation due to the inertia of the drive motor when the drive motor tilts the headlight to face upward, the width will be This would be too narrow if the drive motor were to tilt the headlights downwards.
The drive motor rotates too much, causing problems such as hunting, and the operation becomes extremely unstable. Conversely, if the width is set according to the amount of rotation due to the inertia of the drive motor when the drive motor tilts the headlights downward, the width will be too wide and the headlights will tilt upwards. When the angle of its optical axis cannot be adjusted accurately.

Therefore, the present invention allows the optical axis of the headlamp to remain as set even if the amount of rotation due to the inertia of the drive motor that rotates forward and backward to move the optical axis of the headlamp in the vertical direction varies depending on the direction of rotation. The purpose of the present invention is to provide a new optical axis adjustment device for vehicle headlights that can accurately point the vehicle headlight at an angle and operate stably without causing hunting or the like. an optical axis detection section that outputs an electrical signal, that is, an optical axis detection signal, whose magnitude corresponds to the angle of the optical axis; and an electrical signal, that is, light, whose magnitude corresponds to the set amount of the set angle of the optical axis of the headlight. an optical axis setting section that outputs an axis setting signal; a first comparator that generates a detection signal when the optical axis setting signal is larger than the optical axis detection signal; and a first comparator that generates a detection signal when the optical axis setting signal is larger than the optical axis setting signal. a second comparator that generates a detection signal; a drive motor that rotates forward or reverse depending on the polarity of the voltage applied to the terminal or the terminal to which the voltage is applied to move the optical axis of the headlamp in the vertical direction; and a motor switching circuit controlled by the outputs of the first and second comparators, and at least one of the first and second comparators has a constant difference between the optical axis setting signal and the optical axis detection signal. The detection signal cannot be generated unless the value exceeds the value, and the area where the drive motor is stopped when the optical axis setting signal changes from large to small or from small to large, that is, the anti-hunting area. It is characterized by being made possible.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Details of the optical axis adjustment device for a vehicle headlamp according to the present invention will be described below with reference to embodiments shown in the accompanying drawings.

FIG. 1 shows an example of an optical axis adjustment mechanism used in the optical axis adjustment device for a vehicle headlamp according to the present invention. In the figure, 1 is a headlamp, and 2 is a support member for the headlamp 1. , 3 is a stay for holding the headlamp 1, one end of which is fixed to the vehicle body 4. 5 is a shaft fixed to the other end of the stay 3, and the upper end of the support member 2 of the headlamp 1 is rotatably supported on the shaft 5.

M is a drive motor, which has a built-in speed reducer, and has a pinion 7 fixed to its output shaft 6. 8
is a rack meshed with the pinion 7, and is arranged to move in the longitudinal direction of the vehicle body 4 as the output shaft 6 of the drive motor M rotates. A transmission shaft 9 is integrally formed at the front end of the rack 8.
A ball 10 is integrally formed at the front end of the transmission shaft 9. Reference numeral 11 denotes a receiving portion fixed to the lower end of the support member 2 of the headlamp 1, and the receiving portion 11 has a spherical recess 12 that opens rearward. By fitting the ball 10 at the front end of the transmission shaft 9 into the spherical recess 12, the transmission shaft 9 and the lower end of the support member 2 of the headlamp 1 are connected like a ball joint.

13 is a variable resistor for optical axis detection, and its main body 1
The movable member 3a is fixed to the vehicle body 4 on the back surface of the rack 8 so as to face it at an appropriate distance, and the mover 13b is fixed on the back surface of the rack 8. Each terminal of this variable resistor 13 is connected to an optical axis adjustment circuit, which will be described later, via a lead wire.

When the drive motor M is rotated in the forward and reverse directions, the rack 8 that meshes with the pinion 7 fixed to the output shaft 6 of the drive motor M is moved in the front-rear direction. Then, the lower end of the support member 2 of the headlamp 1, which is connected to the transmission shaft 9 of the pinion 7 in a ball joint, is moved back and forth, and the headlamp 1 uses the shaft 5 supporting the upper end of the support member 2 as a fulcrum. The optical axis is moved vertically. Furthermore, when the rack 8 moves, the mover 13b of the variable resistor 13 moves accordingly, and the resistance value of the variable resistor 13 changes, and the resistance value increases depending on the angle of the optical axis of the headlamp 1. It becomes Satoshi. Two such optical axis adjustment mechanisms are provided corresponding to the left and right headlights. In addition, variable resistor 1 for adjusting the optical axis
3 is provided, for example, only in the left optical axis adjustment mechanism.

Figure 2 shows the drive motor that tilts the left and right headlights 1.
This figure shows an example of an optical axis adjustment circuit that adjusts the angle of the optical axis of the headlamp 1 by rotating ML and MR. In the figure, VR1 is a variable resistor for setting the optical axis angle that moves the position of the mover S according to the rotation of a knob, etc., and VR2 is the variable resistor for detecting the optical axis shown in Figure 1. One terminal of each of the power supply devices 13 is connected to the anode of a power source E via an ignition switch SW, and the cathode of the power source E is grounded. Also, variable resistor VR1 for setting the optical axis.
The other terminal of is grounded via variable resistor VR3 for zero adjustment, and variable resistor VR2, VR13 for optical axis detection.
The other terminal of is directly grounded. When the ignition switch SW is turned on, a voltage is generated between the movers S and D _e of the variable resistors VR1 and VR2 and the ground. The magnitude of this voltage changes depending on the position of the movers s and D _e , and as the movers S and D _e move closer to the terminal connected to the anode of the power source E via the ignition SW, the voltage increases. , conversely, when the terminal moves closer to the ground side, the voltage decreases. Therefore, the voltage between the movable element S of the variable resistor VR1 for setting the optical axis and the ground, that is, the optical axis setting voltage _Vs , has a magnitude corresponding to the amount of operation such as rotation of the knob, and the variable resistor Equipment VR2,
The voltage between the movable element D _e 13b fixed to the rack 8 of the optical axis adjustment mechanism shown in Fig. 1 of 13 and the ground, that is, the optical axis detection voltage _V It becomes the size. In addition, variable resistor VR for zero adjustment
Reference numeral 3 is for finely adjusting the optical axis setting voltage V _D to an appropriate value when the operating amount of the knob etc. is 0.

COM1 and COM2 are voltage comparators made of, for example, differential amplifiers, and are configured to compare the optical axis setting voltage Vs and the optical axis detection voltage _VD . comparator
COM1 receives the optical axis setting voltage V _S at the non-inverting input terminal, receives the optical axis detection voltage V _D at the inverting input terminal, and outputs V _S
>V _D , a voltage V _COM 1 equal to the power supply voltage E is output. _R1 is a positive feedback resistor connected between the output terminal and non-inverting input terminal of the comparator COM1, and this resistor R1 makes the amplification of the comparator COM1 appropriately larger than the amplification inherent to the comparator. Become. comparator
COM2 receives the optical axis detection voltage V _D at the non-inverting input terminal via the resistor R2, receives the optical axis setting voltage V _S at the inverting input terminal, and the voltage received at the non-inverting input terminal via the resistor R2 is When it is larger than the optical axis setting voltage V _S directly received at the inverting input terminal, a voltage V _COM 2 equal to the power supply voltage E is output.

Diodes D1, D2 and resistors R3, R4 constitute a feedback circuit, and the cathode of diode D1 is connected to the output terminal of voltage comparator COM2, and the anode is connected to the non-inverting input terminal of comparator COM2 via resistor R3. has been done. Further, in contrast to the diode D1, the diode D2 has an anode connected to the output terminal of the voltage comparator COM2, and a cathode connected to the non-inverting input terminal of the comparator COM2 via a resistor R4. Therefore, voltage comparator COM2
When the potential of the output terminal is lower than the potential of the non-inverting input terminal, that is, the output voltage from the voltage comparator COM2
Diode D1 when V _COM 2 is not occurring.
is conductive and diode D2 is non-conductive, so
The resistance of the feedback circuit at this time is the resistance R3 connected to the conductive diode D(1).
Also, when the potential of the output terminal of the voltage comparator COM2 is higher than the potential of the non-inverting input terminal, that is, the voltage comparator
When the output voltage V _COM 2 is generated from COM2, diode D2 is conductive and diode D1 is non-conductive, so the resistance of the feedback circuit at that time is equal to the resistance 4 connected to diode D3 which is conductive. Become.

Output voltage V _COM of voltage comparators COM1 and COM2
1 and V _COM 2 are applied to the bases of transistors Q1 and Q2 via resistors R5 and R6, respectively. The emitters of transistors Q1 and Q2 are grounded, and R7 and R8 are resistors connected between the bases of transistors Q1 and Q2 and ground, respectively. One end of RL1 and RL2 is connected to the collectors of transistors Q1 and Q2, and the other end is connected to the power supply E via the ignition switch SW.
The relay is connected to the anode of , and D3 and D4 are its protection diodes. And the voltage comparator
Output voltage from COM1, COM2 V _COM 1, V _COM 2
When this occurs, transistors Q1 and Q2 turn on. Then, the power and ignition switch
SW, relay RL1, RL2 transistor Q1, Q
A closed circuit consisting of relays RL1 and RL is formed.
Current flows through relays RL1 and RL2, and relays RL1 and RL2 operate. Make contacts Ma of relays RL1 and RL2 are connected to a power source E via an ignition switch SW, and break contacts B are grounded. The common terminal C of the relay RL1 is connected to one terminal X of each of the two drive motors ML and MR corresponding to the left and right headlights. Also, relay RL
The common terminal C of the two drive motors ML and MR is connected to the other terminal Y of each of the two drive motors ML and MR. Therefore, when both transistors Q1 and Q2 are in an off state and neither relays RL1 and RL2 are excited, both terminals X and Y of drive motors ML and MR
is kept at ground potential, and conversely, transistor Q
Both relays RL1 and Q2 are on, and relays RL1,
When both RL2 are excited, both terminals X and Y of drive motors ML and MR are kept at the same potential as the anode of power supply E, and in any case, between both terminals of drive motors ML and MR, No voltage is applied and drive motors ML and MR do not rotate. transistor Q
2 is off, transistor Q1 is turned on, and as a result, relay RL1 is energized, and one terminal X of drive motors ML and MR is connected to common terminal C,
Make contact Ma and ignition switch SW
It is connected to the anode of the power source E via. Therefore, the terminals X and Y of the drive motors ML and MR become positive, and the terminals Y of the drive motors ML and MR rotate forward, for example.
Also, when transistor Q1 remains off, transistor Q2 turns on, and relay R2 is energized, the other terminal Y of drive motors ML and MR is connected via common terminal C, make contact Ma, and ignition switch SW. Connected to the anode of power supply E.
Therefore, the terminals Y of the drive motors ML and MR are
Terminal X becomes negative, and drive motors ML and MR rotate in reverse, for example. When the drive motors ML and MR are rotated, for example, in the forward direction (clockwise in Fig. 1), the left and right headlights 1 are directed upward, and the drive motors ML and MR are rotated in the reverse direction (in the counterclockwise direction in Fig. 1). The left and right headlights 1 that are rotated in a clockwise direction are directed downward.

The operation of this optical axis adjustment circuit will be explained below.

(1) When the optical axis setting voltage V _S and the optical axis detection voltage V _D are approximately equal. In this case, comparator COM1 and COM
Since the output voltages V _COM 1 and V _COM 2 of V COM 2 become approximately 0, both transistors Q 1 and Q 2 remain off. Therefore, both relays RL1 and RL2 are not excited, and drive motors ML and MR do not rotate.

(2) When the optical axis setting voltage V _S is higher than the optical axis detection voltage V _D.

Variable resistor for setting optical axis by knob operation etc.
When the mover S of VR1 is moved closer to the terminal connected to the ignition switch SW of the variable resistor VR1, the optical axis setting voltage V _S becomes higher than the increased optical axis detection voltage V _D. Then, an output voltage V _COM 1 is generated from the first voltage comparator COM1, and the transistor Q1 is turned on.
As a result, the relay RL1 is energized, so its common terminal C is connected to the make contact Ma, and the terminals X of the drive motors ML and MR are connected to the anode of the power source E. On the other hand, the second voltage comparator COM2
Since the voltage applied to the inverting input terminal is greater than the voltage applied to the non-inverting input terminal, the output voltage is
Without generating V _COM 2, transistor Q2 remains off and relay RL25 remains de-energized. Therefore, the drive motor ML,
Terminal Y of MR is kept grounded via common terminal C and break contact B of relay RL2, and as a result, drive motors ML and MR rotate in the positive direction, and along with this, the variable Mover D _e of resistor VR2, 13b is variable resistor VR
It is moved closer to the terminal connected to the ignition SWs 2 and 13, and the optical axis detection voltage V _D increases. When the optical axis detection voltage V _D is equal to or larger than the optical axis setting voltage V _S , the comparator
COM1 is in a state where it does not generate the output voltage V _COM1 . Then, the transistor Q1 is turned off and the relay RL1 changes to a non-energized state, and its common terminal C is connected to the break contact B. As a result, the power supply voltage E is not applied to the drive motors ML and MR. However, even in this state, the drive motors ML and MR do not stop immediately, but continue to rotate due to inertia, and the headlight 1 continues to tilt upward, so that the optical axis setting voltage V _S
continues to rise. And then the drive motor
ML and MR stop rotating.

By the way, like this, the second voltage comparator
When the output voltage V _COM 2 is not generated from COM2, that is, when the potential of the output terminal of comparator COM2 is at ground level, the voltage comparators COM1 and
The input side of COM2 is in the state shown in FIG. 3A. That is, in such a case, the resistor R3 becomes the resistor of the feedback circuit as described above, and the potential of the terminal connected to the output terminal of the comparator COM2 becomes the ground level. Then, a voltage dividing circuit that divides the optical axis detection voltage V _D is configured by the resistors R2 and R3 (note that the forward voltage of the diode D1 and the terminal of the transistor (not shown) in the voltage comparator COM2 in the non-conducting state (Ignore voltage, etc.). Therefore, comparator COM2
A voltage V D ' obtained by dividing the optical axis detection voltage V _D by the voltage dividing circuit described above is applied to the non-inverting input terminal _of . Therefore, the optical axis detection voltage V _D is the optical axis setting voltage V _S
Even if the voltage becomes higher than , voltage comparator COM2 outputs voltage V _COM until voltage V _D ' applied to the non-inverting input terminal becomes higher than optical axis setting voltage V _S
2, the Y terminals of the drive motors ML and MR are kept at ground potential, and no voltage is applied to the drive motors ML and MR to rotate them in the opposite direction. Therefore, even after the increasing optical axis detection voltage V _D reaches the optical axis setting voltage V _S , the voltage V _D ' when the drive motors MR, MR, which continued to rotate due to inertia etc., stop, is the optical axis detection voltage. Voltage V _S
If the voltage dividing ratio of the voltage dividing circuit made up of the resistors R2 and R3 is set so as to be smaller than the above, there is no risk of hunting.

In addition, when the drive motors ML and MR tilt the headlight 1 to face upward, that is, rotate in the forward direction, the load received increases by the moment due to the headlight 1's own weight, so the amount of rotation due to inertia increases. is smaller than when rotating in the opposite direction. Therefore, the difference between the optical axis detection voltages V _D and V _D ' required to prevent the hunting phenomenon, that is, the hunting prevention area, can be made smaller compared to case (3) described later. By making the resistance value of resistor R3 relatively large, the voltage dividing ratio of the voltage dividing circuit consisting of R2 and R3 is increased. If the resistance value of the resistor R3 is too small, the hunting prevention area becomes unnecessarily wide, making it impossible to accurately adjust the angle of the optical axis of the headlamp 1 to the set angle, which is not preferable.

(3) When the optical axis detection voltage V _D is higher than the optical axis setting voltage V _S.

Contrary to case (2), a variable resistor for setting the optical axis
When mover S of VR1 is moved closer to the terminal connected to variable resistor R3 of variable resistor VR1, optical axis setting voltage V _S decreases and optical axis detection voltage V _D
becomes smaller than In this case, the first comparator
COM1 does not generate the output voltage V _COM 1, and the second comparator COM2 generates the output voltage V _COM 2. Therefore, the drive motors ML and MR rotate in opposite directions, the headlight 1 is tilted downward, and the optical axis detection voltage V _D increases accordingly.
gradually decreases. And optical axis detection voltage V _D
is the same as or lower than the optical axis setting voltage V _S , the first voltage comparator COM1 outputs a voltage V _COM
Generates 1. Then, the common terminal C of the relay RL1 is connected to the make contact Ma, and as a result, the terminals X of the drive motors ML and MR have the same potential as the anode of the power supply E, while the drive motor
Since the terminals Y of ML and MR maintain the same potential as the anode of the power source E, no voltage is applied to the drive motors ML and MR. However, even under such conditions, the drive motor
ML and MR do not stop immediately due to inertia, (2)
As in the case described above, it takes time for the drive motors ML and MR to stop after the optical axis detection voltage V _D decreases and becomes equal to the optical axis setting voltage V _S , and during that time, the drive motors ML and MR rotates a certain amount due to inertia, the headlight 1 also tilts downward, and the optical axis detection voltage V _D continues to decrease.

By the way, like this, the second voltage comparator
When the output voltage V _COM 2 is generated from COM2, that is, when the potential of the output terminal of comparator COM2 is at the same level as the anode of power supply E, the voltage comparator
The input sides of COM1 and COM2 are in the state shown in FIG. 3B. That is, in such a case, the resistor R4 becomes the resistor of the feedback circuit, and the second
The terminal connected to the output terminal of the voltage comparator COM2 has the same potential as the anode of the power source E.
Then, the power supply voltage E is increased by resistors R2 and R4.
A _{voltage dividing circuit is configured to divide the voltage E-V D ,} which is the difference between
Ignore forward voltage, etc. ), the voltage V _{D '} ' between the connection point of resistor R2 and resistor R4 of the voltage divider circuit and ground is applied to the non-inverting input terminal of comparator COM2. Higher than axis detection voltage V _D. Therefore, even if the gradually decreasing optical axis detection voltage V _D becomes lower than the optical axis setting voltage V _S , the voltage applied to the non-inverting input terminal
The voltage comparator COM2 continues to generate the output voltage _VCOM2 until V _D '' becomes smaller than the optical axis setting voltage V _S , and the Y terminals of the drive motors ML and MR are connected to the power supply E.
is kept at the same potential as the anode of the drive motor
There is not enough voltage applied to ML and MR to rotate them in the forward direction. Therefore, the drive motor ML, which continued to rotate due to inertia etc. even after the decreasing optical axis detection voltage V _D reached the optical axis setting voltage V _S ,
If the resistance ratio of the resistor R4 to the resistor R2 is set so that the voltage V _D '' when the MR is stopped is slightly larger than the optical axis detection voltage V _S , there is no risk of hunting.

Furthermore, when the drive motors ML and MR tilt the headlight 1 to face downward, that is, rotate in the opposite direction, the load received is lightened by the moment due to the headlight 1's own weight, so the rotation due to inertia is reduced. The amount is larger than when rotating in the forward direction. Therefore, the difference between the optical axis detection voltages V _D and V _D '' required to prevent hunting, that is, the hunting prevention area, must be made relatively large, so the resistance value of resistor R4 is made relatively small. By doing so, the ratio of resistance R2 to R4 is increased.

In such an optical axis adjustment device, each input terminal of one of the two voltage comparators COM1 and COM2 which compares the optical axis setting voltage V _S and the optical axis detection voltage V _D is connected to each input terminal of the two voltage comparators COM1 and _COM2 . , V _D are applied directly, and the optical axis detection voltage V _D is applied to the non-inverting input terminal of COM2 via the resistor R2 (in addition, the optical axis setting voltage V _S applied to the inverting input terminal of COM2 is applied directly to that terminal without passing through a resistor.) Furthermore, a feedback circuit is connected between the non-inverting input terminal connected to the resistor R2 of the voltage comparator COM2 and the output terminal, and,
This feedback circuit is connected to the resistor R3 when the output voltage V _COM 2 of the voltage comparator COM2 is not generated due to the action of the diodes D1 and D2, that is, when the output terminal is at ground potential.
When the output voltage V _COM 2 is generated, that is, when the output terminal has the same potential as the anode of the power source E, the resistor R4 functions as the feedback resistor. Therefore, when the optical axis setting voltage V _S is greater than the optical axis detection voltage V _D and the drive motors ML and MR rotate forward to tilt the headlamp 1 upward, the anti-hunting area is The width can be arbitrarily set by setting the resistance value of the resistor R3 to an appropriate value. On the other hand, when the drive motors ML and MR rotate in the opposite direction to tilt the headlight 1 downward, the width of the anti-hunting area is set by the resistor R4.
It can be arbitrarily set by setting the resistance value to an appropriate value. Therefore, the drive motor ML,
The anti-hunting region when the MR rotates in the forward direction and the anti-hunting region when the MR rotates in the reverse direction can be set to widths corresponding to the amount of rotation due to the inertia of the drive motor in the corresponding rotation direction.

The feedback circuit is constructed by connecting a resistor R4 in parallel to a series circuit of a resistor R3 and a diode D1 or D2, as shown in FIGS. 4A and B, thereby reducing the number of diodes used. can be reduced by one.

As described above, in the optical axis adjustment device for a vehicle headlamp of the present invention, the optical axis setting voltage and the optical axis detection voltage are directly applied to the two input terminals of the first voltage comparator, and the optical axis detection voltage is directly applied to the two input terminals of the first voltage comparator. The voltage comparator has a resistor connected to one of its two input terminals so that the terminal receives the optical axis setting voltage or the optical axis detection voltage through the resistor, and the first voltage comparator The one voltage received at the inverting input terminal is received at the non-inverting input terminal, and the other voltage is received at the inverting input terminal.
Further, a feedback circuit is connected between the input terminal and the output terminal of the second voltage comparator to which the resistor is connected, and this feedback circuit is connected to the potential of the input terminal of the second voltage comparator. The resistance value is set to be different when the output terminal is higher than the output terminal and when it is the opposite. Therefore, the optical axis setting voltage is higher than the optical axis detection voltage, and as a result, when the drive motor whose rotation direction is switched by the switching circuit controlled by the two voltage comparators is rotated in the positive direction, for example, Conversely, the optical axis setting voltage is smaller than the optical axis detection voltage, and the width of the hunting prevention region can be set to a different value from when the drive motor is rotated in the opposite direction, for example. Therefore, the anti-hunting area when the drive motor rotates in the forward direction and the anti-hunting area when the drive motor rotates in the reverse direction can be set to widths that correspond to the inertia of the drive motor in the corresponding rotational directions.

Therefore, even if the amount of rotation due to the inertia of the drive motor that moves the optical axis of the headlight in the vertical direction varies depending on the rotation direction of the drive motor, stable operation can be achieved without causing hunting or the like. Furthermore, the optical axis of the headlight can be precisely directed to the set angle.

FIG. 5 shows a modification of the switching circuit and drive motor of the vehicle headlamp of the present invention. The variant uses two solenoids SL ₁ and SL ₂ as switching circuits.
In this embodiment, one relay RL having a common terminal CT is used as a drive motor, and drive motors ML' and MR' each having a common terminal CT and two terminals, that is, a forward rotation terminal PT and a reverse rotation terminal NT. When only one solenoid SL ₁ of the relay RL is energized, its common terminal C is connected to one terminal S ₁ , and when only the other solenoid SL ₂ is energized, its common terminal is connected to the other terminal S. ₂ , and at other times, that is, when both solenoids SL ₁ and SL ₂ are energized, and when neither solenoid SL ₁ and SL ₂ are energized, the terminal S ₁ , such as the common terminal C,
S ₂ is also not connected. One solenoid SL ₁ of the relay RL is a transistor
On the collector side of Q ₁ , the other solenoid SL ₂ is connected to the collector side of transistor Q ₂ . Therefore, the common terminal C is connected to the terminal S1 when only the transistor _Q1 is turned on, and the common terminal C is connected to the terminal _S1 when only the transistor Q1 is turned on, and the common terminal C is connected to the terminal _S1 when only the transistor Q1 is turned on.
When only is turned on, it is connected to terminal _S2 . When both transistors Q ₁ and Q ₂ are turned on and when both are turned off, the common terminal C is in a neutral state in which it is not connected to either the terminals S ₁ or S ₂ .

Furthermore, drive motors ML' and MR' rotate in the forward direction when voltage is applied between the common terminal CT and forward rotation terminal PT, and when voltage is applied between the common terminal CT and reverse rotation terminal NT. is designed to be reversed.

According to this modification, the transistor
When only Q ₁ is turned on, the drive motor ML′,
When MR′ rotates in the normal direction and only transistor Q ₂ is on, the drive motors ML′ and MR′ rotate in reverse, and when both transistors Q ₁ and Q ₂ are on or when both are off, the drive motors ML ′, MR′ stop rotating. Therefore, even if the motor switching circuit is configured with only one relay RL, the drive motors ML′,
The MR can be rotated forward or backward or stopped as appropriate, and the number of relays used can be reduced.

Note that FIG. 1 schematically shows an example of the optical axis adjustment mechanism used in the optical axis adjustment device of the present invention.
This mechanism is merely one example of an optical axis adjustment mechanism that can be used in the optical axis adjustment device of the present invention, and various types of optical axis adjustment mechanisms can be considered that can be used in the optical axis adjustment device of the present invention. etc,
The present invention can be implemented in various ways, and various modifications can be made, and the present invention is not limited to what is shown in the drawings.

[Brief explanation of drawings]

1 to 3 show an example of the implementation of the optical axis adjustment device for a vehicle headlamp according to the present invention, FIG. 1 is a schematic side view showing an example of the optical axis adjustment mechanism used therein, and FIG. The figure is a circuit diagram showing an example of the optical axis adjustment circuit, FIG. 3A is a circuit diagram equivalently showing a part of the optical axis adjustment circuit in a state where the optical axis setting voltage is higher than the optical axis detection voltage, and FIG. 4 is a circuit diagram equivalently showing the same part as shown in A in a state opposite to that in case A, and FIGS. 4A and 4B are modified examples of the feedback circuit of the optical axis adjustment device of a vehicle headlamp according to the present invention, respectively. FIG. 5 is a circuit diagram showing a modification of the switching circuit and drive motor of the optical axis adjustment device of the present invention. Explanation of symbols, 1... Headlight, VR ₁ ... Optical axis setting section, VR ₂ ... Optical axis detection section, COM... Comparison circuit,
ML, MR, ML', MR'... Drive motor, E...
Power supply, RL ₁ , RL ₂ , RL...Motor switching circuit, R ₃ ,
R ₄ , D ₁ , D ₂ ... feedback circuit.

Claims (1)

[Scope of Claims] 1. An optical axis detection section that outputs an electrical signal, that is, an optical axis detection signal, having a size corresponding to the angle of the optical axis of the headlamp;
an optical axis setting section that outputs an electrical signal, that is, an optical axis setting signal, having a magnitude corresponding to the setting amount of the optical axis setting angle of the headlamp; and detecting when the optical axis setting signal is larger than the optical axis detection signal. a first comparator that generates a signal; a second comparator that generates a detection signal when the optical axis detection signal is larger than the optical axis setting signal; and a second comparator that generates a detection signal when the optical axis detection signal is larger than the optical axis setting signal; a drive motor that rotates in forward and reverse directions to move the optical axis of the headlight in the vertical direction; and a motor switching circuit that is controlled by the outputs of the first and second comparators. At least one of the comparators is configured such that it cannot generate a detection signal unless the difference between the optical axis setting signal and the optical axis detection signal exceeds a certain value. 1. An optical axis adjustment device for a vehicle headlamp, characterized in that an optical axis adjustment device for a vehicle headlamp is configured to create an area where a drive motor stops when the drive motor changes from large to large, that is, a hunting prevention area. 2. The vehicle according to claim 1, wherein the width of the anti-hunting area is made different when the optical axis setting signal changes from small to large and when it changes from large to small. Optical axis adjustment device for headlights. 3 An optical axis detection section that outputs a voltage of a magnitude corresponding to the angle of the optical axis of the headlight, and an optical axis detector that can set the angle of the optical axis of the headlight by operating a knob etc. an optical axis setting section that outputs a voltage of the magnitude;
A first input terminal that receives one of the output voltage of the optical axis setting section, that is, the optical axis setting voltage, and the output voltage of the optical axis detection section, that is, the optical axis detection voltage, at a non-inverting input terminal and receiving the other at an inverting input terminal. A resistor is connected to one of the voltage comparators and two input terminals so that the terminal receives an optical axis setting voltage or an optical axis detection voltage through the resistor, and the optical axis setting voltage and the optical axis detection voltage are connected to the voltage comparator. a second voltage comparator that receives one of the voltages at the inverting input terminal of the first voltage comparator and receives the other one at the non-inverting input terminal and the other at the inverting input terminal; and the resistor of the second voltage comparator. A feedback circuit is connected between an input terminal connected to a ,
A drive motor for adjusting the optical axis that rotates forward and backward to move the optical axis of the headlight in the vertical direction, and a first voltage comparator and a second voltage comparator, the two voltage comparators When an output is generated from both or when no output is generated from either, the drive motor and the power source that drives it are electrically cut off, and when an output is generated from only one voltage comparator, the When an output occurs in the first voltage comparator and when the second
An optical axis of a vehicle headlamp, comprising a motor switching circuit that electrically connects a drive motor and a power source so that the direction of rotation is reversed when an output is generated in the voltage comparator of the vehicle. Adjustment device. 4. The feedback circuit consists of two circuits in which a diode and a resistor are connected in series, connected in parallel, and the two resistors have different resistance values, and the anode of one of the two diodes is connected to the output terminal of the comparator. one side, the cathode is connected to the input terminal side, and the other diode has its anode connected to the input terminal side of the comparator,
4. The optical axis adjustment device for a vehicle headlamp according to claim 3, wherein the cathode is connected to the output terminal side. 5. The optical axis adjustment device for a vehicle headlamp according to claim 1, wherein the feedback circuit is formed by further connecting a resistor in parallel to a circuit in which a diode and a resistor are connected in series. .