JPS6180125A - Antidazzle type reflection mirror - Google Patents

Abstract

PURPOSE:To make possible the maintenance of an antidazzle type reflection mirror, for which a liquid crystal element of a negative type display is used, in a non-antidazzle state while a vehicle is not driven by decreasing the transmittance of the liquid crystal element when a key switch is off. CONSTITUTION:The output voltage of a battery 8 loaded on a vehicle is supplied through the key switch 7 to a constant voltage circuit 1. A charging and discharging circuit 2 is charged when the output voltage of the circuit 1 is at a prescribed level or above. The circuit 2 supplies the inside battery voltage to a driving circuit 100 when there is no more output voltage of the circuit 1. The liquid crystal driving circuit 4 in the circuit 100 controls the output phase of an oscillating circuit 6 according to the signal from an antidazzle control circuit 3 and drives liquid crystals 5a, 5b. The circuit 3 detects the brightness of the head light of the succeeding vehicle and the brightness around the vehicle by an optical sensor and determines antidazzle/non-antidazzle. The inter-electrode voltage of the layers 5a, 5b decreases and the transmittance of the liquid crystal element decreases when the supply voltage to the circuit 100 is low while the switch 7 is off.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anti-glare reflector using a liquid crystal element for negative display.

[Conventional technology]

Conventionally, there is an anti-glare reflector using C,/H type liquid crystals (Utility Model Application No. 58-188601). However, while this anti-glare reflecting mirror does not feel out of place with conventional prism mirrors, it is necessary to constantly apply a voltage to ensure that it is non-dazzling during normal times. For this reason, an anti-glare state occurs during non-operation when the key switch is off or when the wiring is disconnected, which poses a practical problem.

On the other hand, there are those that have a built-in solar cell and secondary battery and eliminate external wiring (Japanese Patent Laid-Open No. 58-37601), and those that have a built-in battery,
One that does not require external wiring (Utility Model Application No. 59-41305)
is proposed. Therefore, if a battery is built in and a voltage is constantly applied to the G/H type liquid crystal, the above G/H
This is one solution when using a type liquid crystal.

However, in reality, when driving a negative display liquid crystal like the above-mentioned G/H type liquid crystal, it is necessary to constantly apply a voltage, so a considerably large battery capacity is required. For this reason, simply combining it with a battery would require a large capacity battery, which is not very practical.

[Problem that the invention seeks to solve]

The present invention has been developed in view of the above problem, and focuses on the fact that even if the reflectance of the anti-glare reflector is slightly reduced when the vehicle is not in operation, it is practical - 1: It is not a problem at all. The anti-glare reflector using a negative display liquid crystal element can be kept in a non-glare state when the vehicle is not being driven, without using a power source.

[Means for solving problems]

In order to achieve the above-mentioned technical problem, the present invention includes a negative display liquid crystal element that is disposed in front of a reflector and whose light transmittance decreases when no voltage is applied, and a liquid crystal element that detects light from the rear of the vehicle. an anti-glare control circuit that includes a light sensor and generates an anti-glare signal when the amount of light detected by the rear light sensor is above a predetermined level; and an anti-glare control circuit that generates an anti-glare signal when the anti-glare signal is not generated from the anti-glare control circuit A first level voltage is applied to increase the transmittance of the liquid crystal element, and when an anti-glare signal is generated from the anti-glare control circuit, no voltage is applied to the liquid crystal element to increase the transmittance of the liquid crystal element. In the anti-glare reflector, the reflector is equipped with a drive circuit that reduces the rate, and is configured to perform the above operations by supplying external power from an in-vehicle battery to each of the circuits via a key switch, when the key switch is turned off. An auxiliary power supply means is provided for supplying a voltage lower than the voltage of the external power supply to the drive circuit to apply a second level voltage lower than the first level voltage to the liquid crystal element, and applying the second level voltage. The transmittance of the liquid crystal element is lower than the transmittance of the liquid crystal element when the first level voltage is applied.

〔Effect of the invention〕

Since the present invention has the above configuration, when the vehicle is operated, the anti-glare reflector can be kept in a non-dazzling state by supplying voltage from the on-board battery to the external power source via the key switch, and the vehicle When not in operation, the anti-glare reflector is kept in a non-dazzling state by supplying voltage from the auxiliary power source, and the voltage applied to the liquid crystal element is kept low to reduce power consumption. The anti-glare reflector can be kept in a non-glare state for a long time by means of this method. Therefore, the anti-glare reflector can be used practically without using a large-capacity auxiliary power source.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 is a block diagram showing a schematic configuration of this embodiment. In this FIG. 1, the constant voltage circuit l is the vehicle battery 8.
In order to prevent the operation of the circuit from changing when the battery voltage is received through the key switch 7 and the battery voltage fluctuates, the output voltage is kept constant even if the input voltage fluctuates slightly. It works like this. For this purpose, a series pass regulator, a shunt regulator, a switching regulator, etc. can be used. If boosting is required, only switching regulators can be used.

The charging/discharging circuit 2 includes a battery therein, charges the battery when the voltage from the constant voltage circuit 1 is higher than a predetermined level, and supplies the battery voltage to the drive circuit 100 when the voltage from the constant voltage circuit 1 disappears.

The anti-glare control circuit 3 has the function of detecting the brightness of the headlights of the following vehicle and the brightness of the surroundings of the vehicle using an optical sensor and determining whether to prevent glare or not.

The oscillation circuit 6 is a circuit that generates pulses for AC drive. The oscillation frequency is high when it is detected that the voltage from the constant voltage circuit 1 is higher than a predetermined level;
When the voltage from the constant voltage circuit 1 disappears, it becomes low.

Liquid crystal drive diagram 1/&4 shows that the phase of the oscillation output of the oscillation circuit 6 is controlled according to the signal from the anti-glare control circuit 3, and the liquid crystal 5 is
a, 5b.

The liquid crystals 5a and 5b are negative display liquid crystals (liquid crystals that absorb or scatter light greatly when no voltage is applied) such as parallel-aligned G/H type liquid crystals and parallel-aligned phase change liquid crystals,
Placed in front of the reflector.

FIG. 2 is a schematic longitudinal sectional view of the anti-type 1 reflecting mirror.

In this FIG. 2, 51a, 51b, 51c are transparent glass substrates, 52a, 52b, 52c, 52d are transparent electrodes, 53a, 53b, 53c, 53
d is an alignment film, 54a and 54b are seals, and a liquid crystal layer 5a of G/H type liquid crystal is aligned in parallel between the respective glass substrates so that the light absorption axes are perpendicular to each other.

5b is interposed to form a liquid crystal element. A reflecting mirror 55 is provided on the back side of this liquid crystal element.

These components are attached to a case 57, and the case 57 further houses a battery 24 and a printed circuit board 56 provided with a circuit for driving the liquid crystal. This case 57 is installed in the vehicle interior using an arm 5. Further, 31a is a rear light sensor that detects light from behind the vehicle. 31b is an ambient light sensor that detects the brightness around the vehicle.

Next, the specific configuration of the device shown in FIG. 1 will be explained with reference to FIG. 3. What is shown in FIG. 3 is a circuit for driving a liquid crystal mounted on a printed circuit board 56 inside a case 57. As shown in FIG.

The constant voltage circuit 1 is composed of a known circuit.

In this example, a Zener diode 11 with a Zener voltage of IOV is used, and the Zener diode 11 has a Zener voltage of 11V-? When the input voltage is 30■, it outputs approximately 9.3■.

The charging/discharging circuit 2 is composed of rectifying diodes 21 and 23, a battery 24 connected with four nickel-cadmium batteries, and a current limiting resistor 22. When a constant voltage is supplied from the constant voltage circuit 1, the battery 24 is While being charged, a voltage of approximately 8.6 cm is output from the output terminal.On the other hand, when the key switch 7 is turned off and the output voltage of the constant voltage circuit 1 becomes Ov, the liquid crystal drive circuit 4 and the oscillation circuit 6
4.1 from the battery 24 through the diode 23.
Apply a voltage of v.

The anti-glare control circuit 3 includes a rear light intensity determination circuit 3a, an ambient illuminance determination circuit 3b, a Schmidt 1, and an AND circuit 31C having a rigger function. When the key switch 7 is on, voltage is supplied to this circuit from the constant voltage circuit 1/31 via the diode 15. light intensity foot circuit 3a,
3b is composed of a photoconductive element 318.degree. 31b forming a rear light sensor and an ambient light sensor, respectively, hysteresis comparator circuits 32a to 361, 32b to 36b, and anti-glare timing circuits 37a to 39a and 37b to 39b.

In the rear light intensity determination circuit 3a, the circuit constituted by the photoconductive element 31a and the resistor 32a is a light guide? A voltage that changes depending on the intensity of light incident on the 11 element 31a is output to a hysteresis comparator. The hysteresis comparator consists of an operational amplifier 36;1, reference voltage generating resistors 33a, 34a, and feedback 11 (resistor 35a).

In this rear light intensity detection circuit 3a, when the incident light on the photoconductive element 31a becomes strong, the element resistance decreases, and the operational amplifier 3
The potential of the inverting input terminal of the inverting input terminal 6a decreases, and when the illuminance becomes 2 lux or more, for example, the inverting input terminal voltage becomes lower than the reference voltage, and the comparator output becomes a high level. Next, the surface illuminance of the photoconductive element 31a decreases, for example by 1
Below lux, the comparator output changes to a low level. Further, the circuit constants are set in this way.

Similarly, for the surrounding illuminance determination circuit 3b, for example, approximately 1
When the illuminance becomes 0 lux or less, the comparator output becomes a high level, and when it becomes about 100 lux or more, it changes to a low level.

Anti-glare timing control circuits 37a-39a, 37b-39
b operates as follows. In the rear light intensity determination circuit 3a, when the light intensity changes rapidly, as is typically the case when the vehicle is driving on a rough road, it prevents violent repetition of glare/non-dazzle in response to this. When the light intensity changes from weak to strong, the comparator output becomes high level, the capacitor 39;J is immediately charged through the diode 37a, and the AND circuit 31C and the input terminal become high level.

Of course, if strong light enters from behind, the driver will not feel any glare because it will immediately block the glare. on the other hand,
When the light from the rear becomes weak from a strong state, the comparator output is inverted to a low level, but the AND circuit 31c
The input terminal voltage attenuates with a time constant determined by the product of the capacitor 39a and the resistor 38a. Therefore, the change from anti-glare to non-anti-glare is delayed for several seconds (for example, 3 seconds) to prevent flickering.

The ambient illuminance determination circuit 3b functions to prevent malfunctions when entering a tunnel, for example. When entering the tunnel,
The surroundings suddenly become dark, but the rear is bright, so if you turn on the anti-glare at this time, it will be difficult to see what's behind you.
That is, in this example, the voltage across both lines of the capacitor 39b is
The threshold value of the AND circuit 31c is not reached during the certain period of time. During this time, resistor 38b and capacitor 39b
is proportional to the product of the capacitances, that is, the time constant.

In the opposite case, it is desirable to respond immediately to changes in ambient illumination, so when the comparator output changes to a low level, the input voltage of the AND circuit 31c immediately becomes a low level.

The anti-glare control circuit 3 described above is configured so that the voltage from the constant voltage circuit 1 is O.
When the voltage reaches V, the function is stopped and the output of the AND circuit 31c becomes high impedance, so the voltage level is fixed to a low level by the resistor 41.

The oscillation circuit 6 is an astable multi-by-break circuit composed of three stages of inverters, a resistor, and a capacitor. The oscillation frequency of this circuit is determined by the combined resistance of the resistor 66, 67 and the photoconductive element 65a of the photocoupler 65, and the capacitor 64.
is proportional to the reciprocal of the product of capacitance. When power is supplied from the constant voltage circuit 1, the LED 65d is bright, so the resistance of the photoconductive element 65a is extremely small. Therefore,
The combined resistance is approximately equal to the parallel resistance of resistors 66 and 67. When the voltage supply from constant voltage circuit 1 disappears, LE
D65b becomes light (and the resistance value of the photoconductive element 65a becomes extremely large, and there is no difference from the resistance value of the photoconductive element 65a when it is open. Therefore, the combined resistance becomes the resistance value of the resistor 67, and the oscillation frequency becomes low. (The frequency is higher than the frequency at which flickering occurs.) The liquid crystal drive circuit 4 includes a pull-down resistor 41 and an inverter 42.
, an exclusive OR circuit 44, and a JK flip-flop 43. The square wave from the oscillation circuit 6 is converted by the flip-flop 43 into a square wave with a half frequency and a duty of 50%. The output of the knob 43 is based on the electrodes of the liquid crystal layers 5a, 5b, IJl, llh theory (11
It enters the sum circuit 44. When the output of the AND circuit 31c is at level 11, the power of the inverter 420 is at level (1), and the output is at high level.

At this time, the phase of the output square wave of the flip-flop 43 is inverted by the exclusive OR circuit 44. Therefore,
At this time, an electric field is applied between the illuminated liquid crystal layers 5a and 5b, resulting in a non-glare state. When the output of the AND circuit 31C is at a high level, a square wave in phase with the output of the flipflop 43 appears at the output of the exclusive logic homologous 1♂P44. Therefore, at this time, no electric field is applied between the electrodes of the liquid crystal layers 5a and 5b, resulting in an anti-glare state. Note that in the non-dazzling state, when the key switch 7 is on and the voltage supplied from the charge/discharge circuit 2 to the drive circuit 100 is high,
Since the power supply voltage of each logic element is high and the voltage applied between the electrodes of the liquid crystal layers 5a and 5b is also high, the transmittance of the liquid crystal element becomes high. Further, when the key switch 7 is off and the voltage supplied from the charge/discharge circuit 2 to the drive circuit 100 is low,
Since the power supply voltage of each logic element is low and the voltage applied between the electrodes of the liquid crystal layers 5a and 5b is also low, the transmittance of the liquid crystal element is lower than the above. However, since the vehicle is not in operation, there is no practical problem even if the transmittance decreases slightly.

Therefore, according to the above configuration, when the vehicle is not in operation, the frequency of the drive voltage applied between the electrodes of the liquid crystal layers 5a and 5b is lowered, and the voltage is low, so that the electric power when the vehicle is not in operation is reduced. Consumption can be kept low.

Note that in the above embodiment, a photoconductive element is used to detect light from behind and ambient brightness, but other optical sensors such as photodiodes, phototransistors, and photocells may be used. Good too. In addition, although an example using a nickel-cadmium battery is shown as a secondary battery, the present invention is not limited to this, but is also applicable to lead-acid batteries, lithium secondary batteries,
Organic secondary batteries using materials such as polyacetylene can be used in exactly the same way. Further, as shown in FIG. 4, a large capacity capacitor 25 can be used in combination with a Zener diode 2G. Also, if you allow replacement, you can use not only secondary batteries but also inexpensive manganese dry batteries.

In addition, although the ambient illuminance determination circuit 3b is provided to detect the dark state outside the vehicle, a circuit for detecting the ON state of the light switch is provided instead, and the detection signal is applied to the AND circuit 31c. You can do it like this.

Further, in order to change the emission frequency, a photoconductive element photocoupler is used in the above embodiment, but this may be replaced with a photocoupler using a phototransistor or a photothyrist. Furthermore, as shown in FIG. 5, a relay 69 may be used to short-circuit/open the resistor 68.

In this example, the switch closes only when current is applied to the coil of relay 69. That is, when the voltage is supplied from the constant voltage circuit 1, the oscillation period is determined by the product of the capacitance of the resistor 66 and the capacitor 64, but when the voltage is not supplied from the constant voltage circuit 1, the oscillation period is determined by the product of the capacitance of the resistor 66 and the capacitor 64.
The oscillation period is determined by the product of the sum and the capacitance of the capacitor 64. Further, as shown in FIG. 6, if the contacts of the relay 69 are of the type that opens when energized for 10 seconds, the capacitance of the capacitor 64 can be switched.

Furthermore, although the constant voltage circuit 1 is provided to supply a stabilized voltage to each circuit, a Zener diode that absorbs large voltage noise may be provided instead.

Furthermore, in addition to the above-mentioned functions, power consumption can be further reduced by providing a device that detects whether or not a passenger is in the vehicle and turning off the power when no one is in the vehicle. FIG. 7 shows an embodiment in which the above function is added to the circuit shown in FIG. 3. A switch 73 for detecting the presence or absence of a driver is provided on a driver's seat 72 of an automobile. This switch 73 is connected in L/D between the charge/discharge circuit 2, the oscillation circuit 6, and the liquid crystal drive circuit 4. This switch 73 can be a general macro switch or a switch using pressure-sensitive rubber. When the driver is absent, the switch 73 is in an open state. Therefore, no voltage is applied to the oscillation circuit 6 and the liquid crystal drive circuit 4, and power consumption is zero.

When the driver gets into the vehicle, the switch 73 is closed.

Until the key switch 7 is turned on, power is supplied from the charge/discharge circuit 2 to the oscillation circuit 6 and the liquid crystal drive circuit 4 to drive the liquid crystal element, and the mirror surface is in a state of high reflectance. Therefore, rear confirmation can be easily made.

After the key switch 7 is turned on, power is supplied from the vehicle battery 8, and the charging/discharging circuit 2 shifts to a charging state. When the key switch 7 is turned off, it remains in a non-dazzling state (high reflectance) until the driver leaves the military, as before turning it on, which increases safety and saves battery power. Can be made smaller.

In addition to this example, an occupant sensor using a light emitting diode and a phototransistor, an electrostatic proximity switch, or the like can be used.

FIG. 8 shows an example of using a switch using light. This involves attaching a light emitting diode 71 to the seat, and using a pulsed light emitting drive circuit to turn on the light emitting diode 71 for a short time (for example, l).
It consists of a light emitting section 7 that repeatedly emits light of 0μS) and pauses for a relatively long time (for example, 1 m5), and a light receiving section 9 that receives light from the light emitting section 7. When the driver is not in the seat, a pulsed current flows through the phototransistor 91 provided in front of the driver's seat in response to the pulsed light, and the FET 92
is on, and 93 is off, so that no current flows through the oscillation circuit 6 and the liquid crystal drive circuit 4. Furthermore, when the driver is in the seat, light is blocked, so no current flows through the phototransistor 91, FET 92 is turned off, FET 93 is turned on, and current flows through the oscillation circuit 6 and the liquid crystal drive circuit 4. , keeping the mirror surface at a high reflectance. Note that in this configuration, the light emitting section 7 is embedded in the seat, but it may be attached anywhere as long as it can determine the presence or absence of an occupant.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic vertical sectional view of an anti-glare reflector, FIG. 3 is a detailed electrical circuit diagram of the structure shown in FIG. 1, and FIG. FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are main part electrical circuit diagrams showing other embodiments. 2... Charge/discharge circuit, 3... Anti-glare control circuit, 31a.
... Rear light sensor, 5a, 5b... Liquid crystal layer, 100.
...1 driving circuit.

Claims (4)

[Claims] (1) It has a negative display liquid crystal element that is placed in front of the reflector and whose light transmittance decreases when no voltage is applied, and a rear light sensor that detects light from the rear of the vehicle. an anti-glare control circuit that generates an anti-glare signal when the amount of light detected by the sensor is equal to or higher than a predetermined level; and an anti-glare control circuit that applies a first level voltage to the liquid crystal element when the anti-glare signal is not generated from the anti-glare control circuit. and a drive circuit that increases the transmittance of the liquid crystal element and reduces the transmittance of the liquid crystal element by not applying voltage to the liquid crystal element when an anti-glare signal is generated from the anti-glare control circuit. , an anti-glare reflector configured to perform the above operations by supplying external power from an on-board battery to each of the circuits via a key switch, wherein when the key switch is turned off, the driving circuit is supplied with a voltage from the external power source; An auxiliary power supply means is provided for supplying a low voltage to apply a second level voltage lower than the first level voltage to the liquid crystal element, and the transmittance of the liquid crystal element due to application of the second level voltage is: An anti-glare reflecting mirror characterized in that the transmittance of the liquid crystal element is lower than the transmittance of the liquid crystal element when the first level voltage is applied. (2) The drive circuit has an oscillation circuit for applying an AC voltage to the liquid crystal element, and when receiving voltage supply from the auxiliary power supply means, the frequency of the AC voltage is changed to the voltage of the external power supply. 2. The anti-glare reflector according to claim 1, wherein the anti-glare reflector is lower than when the mirror is being illuminated. (3) The drive circuit includes a determination means for determining whether or not there is a voltage supply from the external power supply, and when the determination means determines that there is no voltage supply from the external power supply, the drive circuit is configured to supply power from the auxiliary power supply means. 3. The anti-glare reflector according to claim 2, wherein the frequency of the alternating current voltage is lowered when voltage is being supplied. (4) The anti-glare reflector according to claim 1, wherein the auxiliary power supply means supplies voltage only to the drive means and does not supply voltage to the anti-glare control circuit.