JPH0121059Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lighting control device for in-vehicle electronic equipment that controls panel illuminance, etc. of the in-vehicle electronic equipment.

BACKGROUND ART Illuminance control (hereinafter also referred to as dayr control) for vehicle instruments has recently become popular in order to reduce driver fatigue caused by glare. on the other hand,
Lighting is essential for in-vehicle electronic devices such as in-vehicle receivers and in-vehicle stereo systems for nighttime operation, but it is desirable to be able to control a dimmer to reduce driver fatigue.

Furthermore, it is desirable to change the illuminance of the in-vehicle electronic equipment in response to changes in the illuminance of the instruments.

Daymer control systems for general vehicles include the systems shown in Figures 1a to 1d.
The conventional system shown in FIGS. 1a and 1b controls the meter lamp 1 by controlling the resistance value of the variable resistor 4.
This method controls the illuminance by changing the current flowing through the lamp. Note that 3 indicates a light switch and 2 indicates a power source. Furthermore, in the conventional system shown in FIGS. 1c and 1d, a chopper means 5 as a dimmer controller is provided in place of the variable resistor 4, and the average value of the current flowing through the meter lamp 1 is controlled by the chopper means 5. This is used to control illumination.

Usually, the system shown in FIGS. 1b and 1d is adopted in which a variable resistor 4 as a control means and one end of a chopper means 5 are on the ground side. The reason for this is that dimmer control cannot be performed even if the other end of the variable resistor 4, the other end of the chopper means 5, etc. are grounded, whereas in the methods shown in Fig. 1 a and c, the power supply 2 is short-circuited. This is because there is a risk that other important lighting, such as a headlight, may go out.

Furthermore, the method shown in FIG. 1d tends to be used more frequently than the method shown in FIG. 1b because it generates less heat during control.

On the other hand, illumination lamps for panel illumination of in-vehicle electronic devices are installed within the operation panel. Generally, these in-vehicle electronic devices are required to be compact and highly functional, and their internal space is extremely small. Therefore, the wiring of the illumination lamp is performed as shown in FIG. 2a. That is, one electrode of the illumination lamp 7 is grounded, and the other electrode of the illumination lamp 7 is connected to the power supply terminal 8. Therefore, by applying a power supply voltage to the terminal 8, the illumination lamp 7 is turned on. Note that 6 indicates an in-vehicle electronic device. On the other hand, there are two locations for taking out voltage from the vehicle's daymer controller: A and B in FIG.
When taking out the voltage from A in FIG. It simply turns on, but cannot control the illuminance.
Furthermore, as shown in FIG. 4, the voltage indicated by B in FIG. 3 is inversely proportional to the average voltage and the illuminance. It is not possible.

In order to eliminate the drawbacks of the case shown in FIG. 2a above, both electrodes of the illumination lamp 7 are led out to terminals 8 and 9, respectively, and connected in parallel with the meter lamp 1, as shown in FIG. 2b. Illuminance is controlled by changing the average current flowing through the lamp 7 by turning on and off the chopper means 5.

However, as shown in FIG. 2B, a new terminal 9 is provided to lead out both electrodes of the illumination lamp 7, and wiring is required, which is disadvantageous in terms of mounting within the on-vehicle electronic device 6.

Moreover, since the chopper means 5 is an intermittent operation,
A square wave from approximately the power supply voltage to approximately zero volts appears at point 9 in FIG. Equipment 6
The disadvantage is that noise may occur in the output.

Furthermore, due to the difference in characteristics between the meter lamp 1 and the illumination lamp 7, the rate of change in illuminance is not necessarily constant. Although a relatively small lamp is used as the illumination lamp 7 for reasons such as mounting space and heat generation, the meter lamp 1 is usually larger than the illumination lamp 7. Therefore, if the illuminance of the instruments is adjusted to a suitable level, the illuminance of the panel surface of the in-vehicle electronic device 6 may be too low.

The present invention has been made in view of the above, and an object of the present invention is to provide a lighting control device for vehicle-mounted electronic equipment that can control illuminance without improving both the daymer controller and the vehicle-mounted electronic equipment.

The present invention will be explained below with reference to examples.

FIG. 5 is a block diagram showing the configuration of an embodiment of the present invention.

In one embodiment of the present invention, the main part is the circuit device shown within the broken line in FIG.

The voltage of the power supply 2 via the light switch 3 is supplied to the illumination lamp ₇ via the transistor Q1 constituting the emitter follower. The base of transistor Q ₁ is grounded through transistor Q ₂ , which has a resistor R ₂ connected to its emitter, and transistor Q ₂
The output voltage of the chopper means 5, that is, the voltage at point RO in FIG. ₃ , is supplied to the base of the capacitor 5 through a smoothing circuit consisting of a resistor _R3 and a capacitor C2.

On the other hand, a resistor R ₁ is connected between the collector and base of the transistor Q ₁ , and the transistor
A capacitor C ₁ is connected between the base of Q ₁ and ground to form a filter.

The operation of one embodiment of the present invention constructed as above will be explained.

When the light switch 3 is closed, the chopper means 5 is operated and the meter lamp 1 is turned on.
Damer control is performed in the same way as in the past. At the same time, due to the operation of the chopper means 5, the output square wave voltage of the chopper means 5 is increased by the resistance R ₃
The voltage is supplied to a smoothing circuit consisting of a capacitor C2 and a capacitor _C2 , and the output voltage of this smoothed smoothing circuit is applied to the base of a transistor _Q2 .
Let this voltage be Vc, and the base of transistor _Q2
If the emitter voltage V _BE2 , then the transistor Q ₂
The emitter current ie ₂ of is ie ₂ = R ₂ / (Vc − V _BE2 ). Here the base current of transistor Q ₂
Since ib ₂ is sufficiently smaller than ie ₂ , transistor Q ₂
The collector current ic ₂ of is ie ₂ ≒ ic ₂ . Therefore, the collector potential Vc ₂ of the transistor Q ₂ becomes Vc ₂ =Vi−R ₁ (ie ₂ +ib ₁ ). Here, Vi represents the voltage of the power supply 2 outputted via the light switch 3, and _ib1 represents the base current of the transistor _Q1 . Since the base current ib ₁ is sufficiently smaller than ie ₂ , the collector potential Vc ₂ becomes Vc ₂ ≈Vi−R ₁ /R ₂ ×(Vc−V _BE2 ).

Here, the voltage V _BE2 takes an almost constant value if the transistor Q ₂ is active, so the collector potential
If the voltage Vi is constant, Vc ₂ becomes a function of the voltage Vc, and its polarity is opposite, that is, the phase is reversed.
The gain will be determined by the ratio R ₁ /R ₂ of resistors R ₁ and R ₂ .

On the other hand, since transistor Q ₁ is an emitter follower that receives voltage Vc ₂ as input, the base-emitter voltage of transistor Q ₁ is V _BE1 and the output voltage is V ₀
Then, V ₀ = Vc ₂ −V _BE1 = Vi−R ₁ /R ₂ ×(Vc−V _BE2 ) −V _BE1 .

The output voltage V ₀ is also considered to be a substantially similar function to the voltage Vc ₂ because the voltage V _BE1 takes a substantially constant value.

Therefore, the voltage of the power supply 2 outputted via the light switch 3 (the voltage at point A), the output power of the chopper means 5 (the voltage at point B), the voltage supplied to the illumination lamp 7, that is, the voltage V ₀ (the voltage at point C) The characteristics showing the relationship between the average voltage applied to the meter lamp 1 (voltage at point A - voltage at point B) and illuminance are as shown in FIG.

As is clear from FIG. 6, since the voltage applied to the illumination lamp 7 and the voltage applied to the meter lamp 1 have the same slope direction, the illuminance can be controlled synchronously by the chopper means 5. Ru. Also, the slope of the voltage applied to the illumination lamp 7 is equal to the resistance _R1 .
Since it is determined by the ratio of the resistance values of R ₂ , the resistances R ₁ and R ₂
By setting the resistance value between the meter lamp 1 and the illumination lamp 7, the visually illuminance change rate of the meter lamp 1 and the illumination lamp 7 can be made almost the same.

Incidentally, the capacitor C ₁ and the resistor R ₁ act as a filter to filter out noise in the power supply line induced by the operation of the chopper means 5 so as not to output it. Yet another light switch 3
When opened, the output voltage V ₀ is prevented from rising suddenly, and a so-called soft start operation is performed.
This is because when the lighting lamp 7 is not lit and its resistance value is low, a sudden rise in the output voltage V ₀ will cause a load current rush phenomenon, which will impact the transistor Q ₁ and induce spike noise. However, this can be avoided.

Next, a modified example of one embodiment of the present invention will be described.

FIG. 7 is a circuit diagram of the main parts showing a modified embodiment of one embodiment of the present invention.

In this modified embodiment, in place of the transistor Q ₁ , transistors Q ₁₀ and Q ₁₁ are connected in a complementary Darlington manner.

Note that transistor Q ₁₀ acts as a drive circuit for transistor Q ₁₁ , and resistor R ₀ acts as a drive circuit for transistor Q 11.
Q is the collector load of ₁₀ .

The operation of this modified embodiment is also similar to that of the embodiment of the present invention.

Therefore, it can be applied when there are a large number of illumination lamps 7 serving as loads and a large output current value is required.

Further, the portion surrounded by a broken line in FIG. 5 (and also the portion shown in FIG. 7) may be provided in the on-vehicle electronic device 6, and an adapter may be provided between the on-vehicle electronic device 6 and the chopper means 5. It may be provided as In this case, the resistor R ₂ may be a variable resistor so that the rate of change in illuminance can be adjusted.

Further, in one embodiment of the present invention, the chopper means 5 is a dimmer controller, but the variable resistor 4 may also be a dimmer controller, and neither of FIGS. 1b and 1d. Applicable.

Further, as shown in FIGS. 2a and 2b, the present invention can be applied regardless of the method of taking out the electrodes of the illumination lamp 7. When applied to the circuit shown in FIG. 2b, the terminal 9 may be grounded.

As described above, according to the present invention, the illuminance of the illumination lamp of the panel of the vehicle-mounted electronic equipment can be changed in accordance with the change in the illuminance of the vehicle meters controlled by the dimmer controller. Therefore, the illuminance can be changed as necessary, such as at night or at dusk, which is effective in alleviating driver fatigue.

In addition, since the output voltage of the dimmer controller is smoothed and used as a control signal, and the transistors connected in series with the load are continuously controlled by the control signal, the circuit itself does not generate noise. In addition, noise generated by the operation of the dimmer controller is blocked by providing a filter that suppresses fluctuations in the power supply voltage.
Illuminance control using lighting lamps can be performed without introducing noise into the interior of on-vehicle electronic equipment. Furthermore, since the rate of change in illuminance can be changed by using a resistor, it is possible to uniformly visually change the illuminance even for combinations of vehicle-mounted electronic devices with different types of vehicles and different lighting conditions.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of daymer control, Fig. 2 is a wiring diagram showing an example of wiring for lighting lamps of in-vehicle electronic equipment, Fig. 3 is a circuit diagram showing voltage extraction from the daimer controller, Fig. 4 5 is a circuit diagram showing the configuration of an embodiment of the present invention. FIG. 6 is an output characteristic diagram for explaining the operation of an embodiment of the present invention.
The figure is a circuit diagram showing the main parts in a modified embodiment of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Meter lamp, 2...Power source, 3...Light switch, 5...Chipper means, 6...In-vehicle electronic equipment, 7...Lighting lamp, _Q1 , _Q2 , _Q10 , _Q11
...transistor.

Claims (1)

[Scope of utility model registration request] A smoothing circuit that smoothes the output voltage of a daimer controller that performs daimer control of vehicle instruments, and a first transistor circuit to which the output voltage of the smoothing circuit is supplied as a control signal and whose gain can be varied by a resistance ratio. , a power supply voltage is supplied via a light switch that applies power supply voltage to a meter lamp illuminating the vehicle instruments, and the power supply voltage is controlled by the output of the first transistor circuit with the lighting lamp of the on-vehicle electronic device as a load. A lighting control device for a vehicle-mounted electronic device, comprising a second transistor circuit and a filter circuit that filters the power supply voltage via the light switch.