JP2971305B2 - Light control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of illumination brightness, and more particularly to the control of a plurality of illumination systems having different supply voltages by receiving an output from a rheostat controller for controlling the brightness of an illuminated display device of an automobile. Device that can be used.

[0002]

2. Description of the Related Art Illumination of an illuminated display device such as a speedometer or the like is generally required to adjust the illuminating light of an illuminating display device such as a speedometer depending on the use environment in the illumination of a vehicle-mounted device. The adjustment is performed by operating the operation unit. However, since audio equipment and the like for a vehicle are mounted on a completed vehicle, it is desirable that the lighting of these devices be controlled in the same manner as the lighting of the equipment originally mounted on the vehicle.

FIG. 4 is a diagram showing characteristics of a rheostat controller. In the figure, (a) is a characteristic diagram of the analog rheostat controller. (B) is a characteristic diagram of the digital rheostat controller. Hereinafter, description will be given according to the drawings. In the analog type, a voltage (or a variable resistance value) from 0 V to the supply voltage is taken out as an output corresponding to the rotation angle of the rheostat controller. On the other hand, the digital rheostat controller extracts voltages having different waveforms having a duty ratio (the ON / OFF ratio of the voltage, expressed as% of ON time per cycle) proportional to the rotation angle. The present invention is applicable to both analog and digital rheostat controllers.

FIG. 5 shows a conventional rheostat dimmer. In the figure, (a) is a block diagram showing a dimming circuit of a lamp, and (b) is a block diagram showing a dimming circuit of a light emitting diode. Hereinafter, description will be given according to the drawings. Reference numeral 1 denotes a rheostat controller. The voltage of the analog type can be varied by the rotation angle of the operation knob, and the duty of the digital type can be varied by the rotation angle of the operation knob. 2 is an integration circuit, and Duty
(In the case of an analog type rheostat, it is regarded as a different output having a duty of 100%, so that the output of the integrator circuit 2 becomes the voltage value and the digital type rheostat is converted to an analog voltage.) It works in the same way as the control circuit). 3, 1
3 is a lamp, 5, 15, 25 and 35 are light emitting diodes. Reference numerals 4 and 14 are current limiting resistors. Reference numerals 7 and 17 are luminance adjusting transistors.

Next, the dimming operation by the digital rheostat controller will be described. By turning the operation knob of the rheostat controller 1, pulses of different duty are output. This pulse is input to the integration circuit 2 and Dut
A pulse having a higher y is converted into an analog signal having a higher output voltage. In the case of the lamp illumination of (a), the voltage is applied to the bases of the transistors 7 and 17, and the brightness of the lamps 3 and 13 is changed. In the case of the light-emitting diode illumination of (b), the voltage is applied to the bases of the transistors 7 and 17 and the brightness of the light-emitting diodes 5, 15, 25 and 35 is changed. In the case of an analog rheostat controller,
The operation is the same except that the output voltage passes through the integrating circuit 2 as it is, and thus the description is omitted. That is, the integration circuit 2
Is provided so that a device (radio) can be connected regardless of whether the rheostat controller 1 provided in the automobile is digital or analog.

[0006]

In the conventional circuit configuration shown in FIG. 5, for example, if the lighting circuits connected to two power supply circuits of 8 V and 13.2 V are controlled, the supply voltages are different. Then, the lamp 13 and the light emitting diodes 25 and 35 of the 8V system are turned off first, and then the lamp 3 and the light emitting diodes 5 and 15 of the 13.2V system are turned off. That is,
There is a problem that the lights of both systems do not turn off at the same time.

As a countermeasure for this, a voltage converter may be provided to make all of them the same voltage, or a plurality of integrating circuits may be provided, but the cost is increased. SUMMARY OF THE INVENTION An object of the present invention is to provide a dimming device that has a simple configuration and is in harmony with the illumination of an illuminated display device of an automobile.

[0008]

In order to achieve the above object, the present invention comprises a first power supply having a first supply voltage and a first lighting element connected downstream of the first power supply. A first control transistor connected downstream of the first lighting element; a second power supply having a second supply voltage lower than the first supply voltage; and a second power supply connected downstream of the second power supply. A second lighting element, a second control transistor connected downstream of the second lighting element, and a rheostat controller that increases an output voltage in accordance with an operation state. An output voltage is applied to a control electrode of the first control transistor and a control electrode of the second control transistor, respectively, so that the first lighting element and the first
And the potential between the second lighting element and the second control transistor is varied to adjust the brightness of the first lighting element and the second lighting element. In the light control device, between the control electrode of the first control transistor and the rheostat controller,
A Zener diode having a constant voltage characteristic corresponding to a difference between a supply voltage of the first power supply and a supply voltage of the second power supply is connected.

A first light-emitting diode group connected in series with a power supply, a predetermined number of light-emitting diodes to be illuminated connected downstream of the power supply, and a first light-emitting diode group connected downstream of the first light-emitting diode group. Light emitting diode, which is provided in parallel with the first control transistor and a light emitting diode to be illuminated having a greater number than the first light emitting diode group and connected in series, is provided. A group, a second control transistor connected downstream of the second light emitting diode group, and a rheostat controller for increasing an output voltage according to an operation state. The first light-emitting diode group and the first control transistor are supplied to a control electrode of a first control transistor and a control electrode of the second control transistor. The potential between the transistor and the potential between the second light emitting diode group and the second control transistor are varied to adjust the luminance of the first light emitting diode group and the second light emitting diode group. In the dimming device, the illumination of the light emitting diodes of the first light emitting diode group has a number corresponding to the difference between the number in the first light emitting diode group and the number in the second light emitting diode group. It is characterized in that unrelated diodes are connected in series.

[0010]

In the high voltage transistor, the voltage supplied to the base of the transistor by the Zener diode is set higher by the Zener voltage. Therefore, the same effect as when the supply voltage is reduced by an amount corresponding to the Zener voltage is obtained. Therefore, lamps or light emitting diodes having different supply voltages are also adjusted at the same timing.

When a different number of light emitting diodes are used, the load condition becomes the same by connecting the light emitting diodes of the different numbers in series, and the light is extinguished at the same timing.

[0012]

FIG. 1 is a view showing a dimming (light emitting diode) device according to an embodiment of the present invention. In the figure, (a) is a diagram of a dimming circuit of a light emitting diode, and (b) is a diagram showing a relationship between a rotation angle of an operation knob of a rheostat controller and voltages of points A and B of a transistor. Hereinafter, description will be made with reference to the drawings.

Reference numeral 1 denotes a rheostat controller, in which the voltage can be varied by the rotation angle in the analog type, and the duty can be varied by the rotation angle in the digital type. Reference numeral 2 denotes an integrating circuit which converts an output from a digital rheostat controller having a different duty into an analog signal (in the case of an analog rheostat, Du is used).
Since the output is regarded as a different output having a voltage of ty 100%, the output of the integrator circuit 2 becomes the voltage value, and operates in the same manner as the digital rheostat control circuit.) 5, 15, 2
Reference numerals 5 and 35 are light emitting diodes. Reference numerals 4 and 14 are current limiting resistors. Reference numerals 7 and 17 are luminance adjusting transistors. Reference numeral 6 denotes a Zener diode for adjusting a base voltage of the transistor 7.

Next, the dimming operation will be described. Turning the operation knob of the rheostat controller 1 causes the rheostat controller 1 to output pulses of different duty.
This pulse is input to the integration circuit 2, and the higher the duty, the higher the output voltage of the analog signal is converted. One of the analog signals is directly input to the base of the transistor 17 of the 8V power supply system to control the current of the 8V power supply system. The other is 13.2V via the Zener diode 6.
12. input to the base of transistor 7 of the power supply system;
The current of the 2V power supply system is controlled.

FIG. 3B shows the voltages at points A and B on the emitter side of the transistors 7 and 17 corresponding to the rotation angle of the operation knob of the rheostat controller 1 when a zener diode is used. Is higher by the Zener voltage. That is, the 13.2 V system is supplied with 5.2 V at point A even when the rotation angle of the rheostat controller is 0. As a result, the timing when the current flowing through the transistors 7 and 17 becomes 0 (the voltage of the integrating circuit 2) becomes the same.

FIG. 2 is a diagram showing a rheostat dimming (lamp) device according to one embodiment of the present invention. In the figure, 3, 1
Except that 3 is a lamp, the relationship between the rotation angle of the operation knob of the rheostat controller and the output voltage is exactly the same as that of FIG. FIG. 3 is a diagram showing a light control device according to another embodiment of the present invention. In some cases, the number of light emitting diodes for lighting of the device cannot always be the same for all circuits due to restrictions on the circuit configuration. A light emitting diode emits light when a voltage of about 2 V is normally applied. Therefore, if the number changes in terms of the circuit configuration, the luminance changes and the extinction timing does not become the same. A method of causing a voltage drop by changing the value of the current limiting resistor is also conceivable, but the resistor and the diode do not exhibit the same voltage-current characteristics (the resistor changes its current linearly with respect to the voltage, but the diode Since the current suddenly increases after a certain voltage and becomes conductive, it is impossible to make the same luminance and the same extinction timing. This embodiment proposes a circuit dimming device using a different number of light emitting diodes, in which (a) shows a dimming circuit diagram using dummy light emitting diodes, and (b) shows a general dimming circuit. It is the light control circuit diagram used. Hereinafter, description will be made with reference to the drawings.

1 is a rheostat controller, 2 is an integration circuit,
45, 55 and 65 are light emitting diodes, 24 and 3 respectively.
Reference numeral 4 denotes a current limiting resistor, and reference numerals 7 and 17 denote luminance adjusting transistors. 8 is a light emitting diode whose emission light is other than visible light, 9
Is a dummy diode. In (a), the same condition as when the same number of light emitting diodes are connected is obtained by connecting the light emitting diodes 8 other than the visible light in a shortage in number. Also, in FIG.
Are connected in series by an insufficient number, the same conditions as when the same number of light emitting diodes are connected are obtained. In this case, it is desirable that the diode has substantially the same characteristics as the light emitting diode.

According to the present invention, in a lighting circuit in which different numbers of light emitting diodes are used, by using dummy diodes, the same effect as when the number of light emitting diodes is made equal can be obtained. An inexpensive dimmer can be configured with the controller and the integrating circuit.

[0019]

As described above in detail, according to the present invention, the dimming of the illumination in harmony with the illuminated display device can be performed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a rheostat light control device (light emitting diode) according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a rheostat dimmer (lamp) according to one embodiment of the present invention.

FIG. 3 is a circuit diagram showing a rheostat dimmer according to another embodiment of the present invention.

FIG. 4 is a diagram showing characteristics of a rheostat controller.

FIG. 5 is a circuit diagram showing a conventional rheostat dimmer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... rheostat controller 2 ... integrating circuit 3, 13 ... lamp 4, 14, 24, 34 ... current limiting resistance 5, 15, 25, 35, 45, 55 ... light emitting diode 6 ... Zener diode 7, 17 ... Transistor 8 ... Light emitting diode 9 ... Diode

Claims (2)

(57) [Claims] A first power supply having a first supply voltage;
A first lighting element connected downstream of the first power source;
A first control transistor connected downstream of the first lighting element; a second power supply having a second supply voltage lower than the first supply voltage; and a second power supply connected downstream of the second power supply. A second lighting element, a second control transistor connected downstream of the second lighting element, and a rheostat controller for increasing an output voltage according to an operation state, wherein an output of the rheostat controller is provided. A voltage is applied to a control electrode of the first control transistor and a control electrode of the second control transistor, respectively, to supply a potential between the first lighting element and the first control transistor, and the second lighting In a dimming device configured to vary the potential between an element and the second control transistor to adjust the luminance of the first lighting element and the second lighting element, the control voltage of the first control transistor may be adjusted. A zener diode having a constant voltage characteristic corresponding to a difference between a supply voltage of the first power supply and a supply voltage of the second power supply is connected between the pole and the rheostat controller. Light control device. 2. A first light-emitting diode group connected in series with a power supply, a predetermined number of light-emitting diodes to be illuminated connected downstream of the power supply, and a first light-emitting diode group connected downstream of the first light-emitting diode group. Light emitting diode, which is provided in parallel with the first control transistor and a light emitting diode to be illuminated having a greater number than the first light emitting diode group and connected in series, is provided. A group, a second control transistor connected downstream of the second light emitting diode group, and a rheostat controller for increasing an output voltage according to an operation state. The first group of light emitting diodes and the first control transistor are supplied to a control electrode of a first control transistor and a control electrode of the second control transistor. The potential between the first light emitting diode group and the second light emitting diode group is adjusted by changing the potential between the second light emitting diode group and the second light emitting diode group. In the dimming device, illumination having a number corresponding to the difference between the number in the first light emitting diode group and the number in the second light emitting diode group is applied to the light emitting diodes of the first light emitting diode group. A dimmer, wherein unrelated diodes are connected in series.