JP2002283914A - Vehicle glare-proof mirror device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excess voltage from being applied to an electrochromic cell, etc., and an excess current flow by a simple circuit constitution using no custom IC in a vehicle glare-proof mirror device capable of varying an applied voltage to the electrochromic cell built in a mirror for visually recognizing a rear side corresponding to a difference of light amount at front and rear sides of the vehicle. SOLUTION: A resistance 67 for restricting a current and an NPN transistor 68 in which a buffering amplifier 71 is connected to a base are connected in series between a switching element 69 connected to the electrochromic cell 18, so as to switch a conduction/cut off corresponding to the difference of light amount at the front and rear sides of the vehicle, and a power source line 66. A reference voltage circuit 72 for producing the maximum absolute voltage of the electrochromic cell 18 is connected to a non-reverse rotation input terminal of the buffering amplifier 71 and an emitter of the NPN transistor 68 is connected to a reverse rotation input terminal of the buffering amplifier 71.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-glare mirror device for a vehicle, and more particularly to an anti-glare mirror device for a vehicle, in which a voltage applied to an electrochromic cell incorporated in a rear view mirror is detected by a rear light amount detection sensor. The present invention relates to an improvement in an anti-glare mirror device for a vehicle which can be changed in accordance with a difference between a light amount on a vehicle side and a light amount on a front side of a vehicle detected by a front light amount detection sensor.

[0002]

2. Description of the Related Art Conventionally, such an apparatus is disclosed in
This is known from, for example, Japanese Patent Application Publication No. 00-212428.

[0003]

If a voltage higher than the maximum absolute voltage is applied to the electrochromic cell, the electrochromic cell will be damaged. Therefore, it is necessary to prevent the application of a voltage higher than the maximum absolute voltage. No. Also, when the electrochromic cell is damaged for any reason or a short circuit occurs on the output side of the drive circuit section, a large current flows through the drive circuit section including the switching element such as a transistor, and the switching element, etc. It is also necessary to prevent the occurrence of burnout. Conventionally,
In order to prevent such overvoltage and overcurrent, an expensive custom IC is used. From the viewpoint of cost reduction, it is desired to prevent overvoltage and overcurrent with a simple circuit configuration that does not use a custom IC.

[0004] The present invention has been made in view of such circumstances, and it is a custom IC to prevent an overvoltage from being applied or an overcurrent from flowing to an electrochromic cell or the like.
It is an object of the present invention to provide an anti-glare mirror device for a vehicle which can be prevented by a simple circuit configuration not using a mirror.

[0005]

In order to achieve the above-mentioned object, the present invention relates to a method for detecting a voltage applied to an electrochromic cell incorporated in a rear-viewing mirror by using a rear-light-amount detecting sensor. The anti-glare mirror device for a vehicle, which can be changed according to the difference between the light amount of the vehicle and the light amount on the front side of the vehicle detected by the front light amount detection sensor, the rear side of the vehicle detected by the rear light amount detection sensor A current limiter is provided between the power supply line and a switching element connected to the electrochromic cell so as to switch between conduction and cutoff in accordance with a difference between the light quantity and the light quantity on the front side of the vehicle detected by the front light quantity detection sensor. And an NPN transistor connected to a base of the buffer amplifier are connected in series, and the non-inverting input terminal of the buffer amplifier is Reference voltage circuit is connected to produce a maximum absolute voltage Kkuseru, to the inverting input terminal of the buffer amplifier, characterized in that it is connected to the emitter of the NPN transistor.

According to such a configuration, the current provided to the electrochromic cell is limited by the resistor provided between the power supply line and the NPN transistor, and the NPN transistor is destroyed when the electrochromic cell is destroyed or the output terminal of the drive circuit is short-circuited. Burnout of the transistor and the switching element can be prevented. Further, the buffer amplifier controls on / off of the NPN transistor so that the emitter voltage of the NPN transistor, that is, the voltage acting on the switching element becomes the maximum absolute voltage of the electrochromic cell determined by the reference voltage circuit. In addition, a voltage higher than the maximum absolute voltage is not applied to the electrochromic cell. That is, the application of an overvoltage or the flow of an overcurrent to an electrochromic cell or the like is determined by the resistance, NP
This can be prevented by a simple circuit configuration using an N transistor and a reference voltage circuit, and the cost can be reduced by not using a custom IC.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on one embodiment of the present invention shown in the attached drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is a perspective view of an anti-glare mirror device, FIG. 2 is a partial longitudinal sectional view of a mirror, and FIG. 3 is a drive / control device. FIG. 4 is a circuit diagram showing a circuit configuration, and FIG.
FIG. 3 is a circuit diagram showing a configuration of a driving unit.

First, in FIG. 1, a housing 12 of an anti-glare mirror device 11 is mounted on a vehicle body at a front portion in a vehicle interior, and is opened toward a rear side along a front-rear direction of the vehicle when mounted on the vehicle body. An opening 13 is provided in the housing 12, and a mirror 14 for rear view is attached to the housing 12 so as to close the opening 13.

In FIG. 2, the mirror 14 is formed by sandwiching an electrochromic cell 18 between a back surface of a first glass 15 and a front surface of a second glass 16 having a reflection film 17 formed on the back surface. , Electrochromic cell 1
8 comprises an electrochromic cell 19 made of an organic polymer film and transparent conductive films 20 and 21 provided on both surfaces.
The mirror 14 is attached to the housing 12 with the front side of the first glass 15 facing rearward in the front-rear direction of the vehicle.

Referring again to FIG. 1, on the front side of the housing 12 below the opening 13, a first photodiode 22 as a rear light amount detecting sensor for detecting the light amount on the rear side along the front-rear direction of the vehicle, An indicator 23 indicating which of the auto-dimming mode and the manual-dimming mode is selected; a mode changeover switch 24 for switching between the auto-dimming mode and the manual-dimming mode by manual operation by a vehicle occupant; Is provided.

The indicator 23 is illuminated in green when the automatic glare mode is selected, and is illuminated in red in both the glare state in the automatic glare mode and the manual glare mode. Second light emitting diode 2
6 and a third light-emitting diode 27 that lights up in green when the manual anti-glare mode is selected.
The third to third light emitting diodes 25 to 27 are arranged in this order on the front surface side of the housing 12.

Although not shown in FIG. 1, a second photodiode 28 (see FIG. 3) serving as a front light amount detecting sensor for detecting the light amount on the front side of the vehicle is provided on the front side of the housing 12 along the front-rear direction of the vehicle. ) Is attached.

In FIG. 3, the voltage applied to the electrochromic cell 18 built in the mirror 14 is controlled by a drive / control device 30. The drive / control device 30 Is stored.

The drive / control device 30 has a power supply circuit 33 connected to a battery 32 via an ignition switch 31 and an automatic anti-glare mode or a manual anti-glare mode in accordance with a switching operation of a mode changeover switch 24. Mode selecting means 34 capable of outputting the selected signal, a first amplifier circuit 35 for amplifying the output of the first photodiode 22,
Connection of the second amplifier circuit 36 for amplifying the output of the second photodiode 28, the differential amplifier 37 for amplifying the output difference between the first and second amplifier circuits 35 and 36, and the connection between the mode selection means 34 and the differential amplifier 37 A comparator 39 having a point 38 connected to the inverting input terminal and a connecting point of the voltage dividing resistors 40 and 41 being input to the non-inverting input terminal;
4, a driving unit 42 for applying a voltage to the electrochromic cell 18 in accordance with the outputs of the differential amplifier 37 and the comparator 39.

The comparator 39 compares the reference voltage with hysteresis input to its non-inverting input terminal with the voltage at the node 38 input to the inverting input terminal. For example, a low level signal is input to the driving means 42 when the voltage becomes 0.6 V or more, and
A high-level signal is input to the driving means 42 in response to the voltage of the voltage 8 being less than 0.5 V, for example. Comparator 3
9, the second light emitting diode 2 is turned on in response to the output of the comparator 42 going low.
6 is connected.

In FIG. 4, the mode selecting means 34 includes a flip-flop 43, and an output terminal 44 of the flip-flop 43 is connected to the base of an NPN transistor 46 connected in series to the third light emitting diode 27. , The negative output terminal 45 of the flip-flop 43 is connected to the base of an NPN transistor 47 connected in series to the first light emitting diode 25. Therefore, when the output of the output terminal 44 becomes high level, the NPN transistor 46 is turned on, so that the third light emitting diode 27 is turned on by the power supplied from the power supply circuit 33,
When the output of the negative output terminal 45 becomes a high level, the NPN transistor 47 is turned on, so that the first light emitting diode 2
5 lights up.

The third light emitting diode 27 and the NPN
The connection point of the transistor 46 is connected to the base of a PNP transistor 48 whose emitter is connected to the power supply circuit 33. The collector of the PNP transistor 48 is
Grounded through resistors 49 and 50 connected in series.
A connection point 38 between the differential amplifier 37 and the mode selection means 34 is connected between the resistors 49 and 50.
The portion between 50 functions as an output terminal of the mode selection means 34.

Therefore, when the output of the output terminal 44 of the flip-flop 43 is at the high level,
When the first light emitting diode 25 is turned off based on the fact that the light emitting diode 27 is turned on and the output of the negative output terminal 45 becomes low level, the PNP transistor 48
Is conducted, and the voltage divided by the resistors 49 and 50 is applied to the connection point 38 assuming that the manual anti-glare mode is selected. At this time, the voltage applied to the connection point 38 is
For example, it is set to 1.1V.

On the other hand, when the output of the negative output terminal 45 of the flip-flop 43 is at a high level,
The third light emitting diode 27 is turned on based on the fact that the light emitting diode 25 is turned on and the output of the output terminal 44 becomes low level.
Is off, the PNP transistor 48 is shut off, and the automatic glare mode is selected.
No voltage is applied to 8 from the mode selection means 34 side.

The negative output terminal 45 is connected to the D input terminal 51 of the flip-flop 43. The clock input terminal 52 of the flip-flop 43 is connected to a connection point of voltage-dividing resistors 53 and 54 connected in series, and the collector of a PNP transistor 55 whose emitter is connected to the power supply circuit 33 is connected to these nodes. Grounded through voltage dividing resistors 53 and 54. Moreover, the base of the PNP transistor 55 is connected to the power supply circuit 33 via the resistors 56 and 57, and the connection point of the resistors 56 and 57 is grounded via the resistor 58 and the mode switch 24.

Further, capacitors 59 and 60 are connected to the connection points of the voltage dividing resistors 53 and 54 and the connection points of the resistances 56, 57 and 57 for absorbing the chattering of the mode changeover switch 24 and the noise of the line from the power supply circuit 33. Is connected.

When the mode switch 24 is turned on while the power is supplied from the power supply circuit 33 to the mode selecting means 34 by the conduction of the ignition switch 31, the PNP transistor 55 is turned on, and The voltage divided by the piezoresistors 53 and 54 is input to the clock input terminal 52 of the flip-flop 43 to change the selection from the automatic anti-glare mode to the manual anti-glare mode, and the output from the output terminal 44 of the flip-flop 43 is output. High level.
When the mode change switch 24 is operated again to conduct the current, the selection is changed from the manual anti-glare mode to the automatic anti-glare mode, and the output from the negative output terminal 45 of the flip-flop 43 becomes high level.

Further, the power supply circuit 33 includes an electrolytic capacitor 6
1 and a resistor 62 are connected to the ground, and a connection point between the electrolytic capacitor 61 and the resistor 62 is connected to the reset input terminal 64 of the flip-flop 43. Thus, in the initial stage of conduction of the ignition switch 31 for igniting the engine mounted on the vehicle, the flip-flop 43 is always reset regardless of the switching mode of the mode changeover switch 24, and the automatic anti-glare mode is selected. The output of the output terminal 45 becomes high level.

That is, the mode selection means 34 is provided with the ignition switch 31 for igniting the engine mounted on the vehicle.
When the ignition switch 31 is in the conductive state, the mode switch 24 is turned on.
The automatic glare mode and the manual glare mode are selectively selected according to the switching operation.

First and second photodiodes 22 and 2
And second amplifier circuits 35 and 36 for amplifying the output of
The differential amplifier 37 amplifies the difference between the light quantity on the rear side of the vehicle detected by the first photodiode 22 and the light quantity on the front side of the vehicle detected by the second photodiode 28. In other words, when the mode selection unit 34 selects the automatic selection mode, a voltage corresponding to the difference between the light amounts on the rear side and the front side of the vehicle is output to the connection point 38 with the mode selection unit 34.

In FIG. 5, a driving means 42 includes a resistor 67, an NPN transistor 68, an NPN transistor 69 as a switching element, and a resistor 70 connected in series between a power supply line 66 connected to the power supply circuit 33 and ground.
A buffer amplifier 71 connected to the base of an NPN transistor 68; and a reference voltage circuit 72 for generating a reference voltage input to a non-inverting input terminal of the buffer amplifier 71.
A buffer amplifier 78 connected to the base of the NPN transistor 69 and connected to the connection point 38 at the non-inverting input terminal; an NPN transistor 79 provided between the base of the NPN transistor 69 and ground; An NPN transistor 81 connected to a connection point 80 of the resistor 70 is provided. The connection point 80 of the NPN transistor 69 and the resistor 70 is connected to one end of the electrochromic cell 18, and the other end of the electrochromic cell 18 is grounded.

The resistor 67 is connected to the electrochromic cell 1
In addition to the function of limiting the current flowing through the NPN transistor 8, the function of preventing the NPN transistors 68 and 69 from being burned when the electrochromic cell 18 is broken or the output terminal of the driving means 42 is short-circuited.

The reference voltage circuit 72 includes a resistor 73 and a capacitor 74 connected in series between the power supply line 66 and the ground, a shunt regulator IC 75 connected in parallel to the capacitor 74, and a voltage divider connected in parallel to the shunt regulator IC 75. Resistors 76 and 77 are provided, and a connection point between the voltage dividing resistors 76 and 77 is connected to a non-inverting input terminal of the buffer amplifier 71.

The shunt regulator IC 75 is for temperature assurance.
Is limited by the resistor 73. Further, the capacitor 74 is for noise suppression of the shunt regulator IC 75.

In such a reference voltage circuit 72, the voltage of the power supply line 66 is reduced to, for example, 2.5 V by the resistor 73, and the voltage of 2.5V is divided by the voltage dividing resistors 76 and 77, so that the electrochromic The absolute maximum voltage of the cell 18, for example, a reference voltage of 1.1 V is applied to the buffer amplifier 71.
Is input to the non-inverting input terminal.

On the other hand, the emitter voltage of the NPN transistor 68 is input to the inverting input terminal of the buffer amplifier 71, and the voltage output from the buffer amplifier 71 is applied to the base of the NPN transistor 68 via the current limiting resistor 82. Is entered. Therefore, buffer amplifier 71 controls ON / OFF of NPN transistor 68 such that the emitter voltage of NPN transistor 68, that is, the collector voltage of NPN transistor 69, becomes a reference voltage determined by reference voltage circuit 72, for example, 1.1V. Become.

The voltage at the connection point 38 is input to the non-inverting input terminal of the buffer amplifier 78. That is, the voltage of 1.1 V output from the mode selecting means 34 when the mode selecting means 34 selects the manual anti-glare mode, and the rear side and the front side of the vehicle when the mode selecting means 34 selects the automatic anti-glare mode. The voltage output from the differential amplifier 37 according to the light amount difference is input to the non-inverting input terminal of the buffer amplifier 78.

The inverting input terminal of the buffer amplifier 78 has NP
The emitter voltage of the N-transistor 69, that is, the voltage applied to the electrochromic cell 18 is input, and the voltage output from the buffer amplifier 78 is applied to the current limiting resistor 8
3 is input to the base of the NPN transistor 69. Therefore, the buffer amplifier 78 controls on / off of the NPN transistor 69 so that the reference voltage input from the connection point 38 is applied to the electrochromic cell 18.

The collector of the NPN transistor 79 whose emitter is grounded is connected to the base of the NPN transistor 69 and the resistor 83. The output of the comparator 39 is input to the base of the NPN transistor 79.
Therefore, the NPN transistor 79 shuts off in response to the output of the comparator 39 changing from the high level to the low level in response to the voltage at the connection point 38 becoming equal to or higher than 0.6 V, for example. On
The turning off will be controlled by the buffer amplifier 78.
Further, as the voltage at node 38 becomes less than 0.5 V, for example, the output of comparator 39 changes from low level to high level, and NPN transistor 79 conducts. NPN transistor 69 remains off regardless of the output of
No voltage is applied to the electrochromic cell 18.

The NPN transistor 81 is used to reduce the time required for the electrochromic layer 19 to return from the colored state to the original state when the application of the voltage to the electrochromic cell 18 is stopped to bring the electrochromic layer 18 into the non-glare state. The NPN transistor 81 is turned on in response to the output of the comparator 39 changing from the low level to the high level, and the charge of the electrochromic cell 18 is discharged through the NPN transistor 81. Will be done. Thereby, the decoloring speed of the electrochromic layer 19 is increased.

Further, a capacitor 84 for preventing static electricity is connected in parallel to the electrochromic cell 18, and a resistor 70 between the emitter of the NPN transistor 69 and the ground functions as a capacitor 84 and a charge discharging resistor of the electrochromic cell 18. I do.

Next, the operation of this embodiment will be described. The anti-glare mirror device 11 converts the voltage applied to the electrochromic cell 18 into the amount of light on the rear side of the vehicle detected by the first photodiode 22 and the second photo diode. An automatic anti-glare mode that changes according to the difference in the amount of light on the front side of the vehicle detected by the diode 28, and a constant voltage applied to the electrochromic cell 18 irrespective of the amount of light detected by the first and second photodiodes 22 and 28. And a mode switching switch 24 for manually selecting the automatic glare mode or the manual glare mode, and an ignition switch for igniting an engine mounted on the vehicle. In the initial stage of the conduction of 31, the automatic anti-glare mode is set regardless of the switching mode of the mode changeover switch 24. While-option includes a mode selecting means 34 for alternatively selecting the auto-dimming mode and manual anti-glare mode according to the switching operation of the mode changeover switch 24 in the conducting state of the ignition switch 31.

Therefore, when the ignition switch 31 is turned on to drive the vehicle, the automatic glare mode is reliably selected, and even if the vehicle driver forgets to operate the switch for bringing the mirror 14 into the glare-proof state. Thus, the mirror 14 can be reliably brought into the anti-glare state.

When it is desired to select the manual anti-glare mode, the mode switch 24 may be operated after the ignition switch 31 is turned on. By operating the mode switch 24, the automatic anti-glare mode and the manual anti-glare mode are selected. It can be selected uniformly and freely.

The housing 12 of the anti-glare mirror device 11
Is provided with an indicator 23 that indicates which state of the automatic glare mode or the manual glare mode, and when the mode switch 24 is operated to switch between the automatic glare mode and the manual glare mode, It is possible to reliably determine which mode is selected.

Further, in the driving means 42, a current limiting device is provided between the power supply line 66 and the NPN transistor 60 which is turned on / off by the buffer amplifier 78 so as to control the voltage applied to the electrochromic cell 18. Are connected in series. Therefore, power supply line 66 and NPN
The current flowing through the electrochromic cell 18 is limited by a resistor 67 provided between the transistors 68, and the NPN transistor 6
8, 69 can be prevented from being burned.

Further, a reference voltage circuit 72 for generating the maximum absolute voltage of the electrochromic cell 18 is connected to the non-inverting input terminal of the buffer amplifier 71 connected to the base of the NPN transistor 68. Is connected to the emitter of the NPN transistor 68. Therefore, the buffer amplifier 71 turns on / off the NPN transistor 68 such that the emitter voltage of the NPN transistor 68, that is, the voltage acting on the NPN transistor 69 becomes the maximum absolute voltage of the electrochromic cell 18 determined by the reference voltage circuit 72. Since the control is performed, a voltage higher than the maximum absolute voltage is not applied to the electrochromic cell 18.

The driving circuit 42 for preventing the overvoltage from being applied to the electrochromic cell 18 and the overcurrent from flowing in the above manner includes a resistor 67, an NPN transistor 68 and a reference voltage circuit. 7
2 and the cost can be reduced by not using a custom IC.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible.

[0046]

As described above, according to the present invention, a simple circuit configuration using a resistor, an NPN transistor, and a reference voltage circuit can be used to determine whether an overvoltage is applied or an overcurrent flows to an electrochromic cell or the like. The cost can be reduced by not using a custom IC.

[Brief description of the drawings]

FIG. 1 is a perspective view of an anti-glare mirror device.

FIG. 2 is a partial longitudinal sectional view of a mirror.

FIG. 3 is a diagram showing a circuit configuration of a drive / control device.

FIG. 4 is a circuit diagram showing a configuration of a mode selection means.

FIG. 5 is a circuit diagram showing a configuration of a driving unit.

[Explanation of symbols]

11 ... Anti-glare mirror device 14 ... Mirror 18 ... Electrochromic cell 22 ... First photodiode as rear light quantity detection sensor 28 ... Second photodiode as front light quantity detection sensor 66 ..Power supply line 67: resistor 68: NPN transistor 69: NPN transistor as switching element 71: buffer amplifier 72: reference voltage circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2K001 AA10 EA20 5J055 AX02 AX04 AX14 AX32 AX53 BX12 BX16 BX44 CX01 CX11 CX28 DX03 DX43 DX53 DX72 DX83 EX02 EX03 EX06 EY01 EY10 EY13 EY17 EZ10 FX20 FX05 FX08 FX08 FX08 FX08 FX08 FX08 FX08 FX08 FX08 FX08 FX08 FX05 FX08 AA03 BB51 CC09 EE08 FF09 GG14

Claims (1)

[Claims] 1. A voltage applied to an electrochromic cell (18) built in a mirror (14) for rear view,
A vehicle protection system capable of changing according to the difference between the light amount on the rear side of the vehicle detected by the rear light amount detection sensor (22) and the light amount on the front side of the vehicle detected by the front light amount detection sensor (28). In the glare mirror device, conduction / interruption is switched according to the difference between the light amount on the rear side of the vehicle detected by the rear light amount detection sensor (22) and the light amount on the front side of the vehicle detected by the front light amount detection sensor (28). Between the switching element (69) thus connected to the electrochromic cell (18) and the power supply line (66).
A current limiting resistor (67) and an NPN transistor (68) having a base connected to a buffer amplifier (71) are connected in series, and the non-inverting input terminal of the buffer amplifier (71) is connected to the electrochromic cell. (18) A vehicle, wherein a reference voltage circuit (72) for generating a maximum absolute voltage is connected, and an inverting input terminal of the buffer amplifier (71) is connected to an emitter of the NPN transistor (68). Anti-glare mirror device.