JPH10250477A - Lamp lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a disconnection and an overload in a lamp by providing a detection means which generates a disconnection detection signal or an overload detection signal when a detected voltage outputted from a current-voltage converting means deviates from the predetermined voltage range. SOLUTION: When a lamp lighting switch is turned and a headlight driving switch output is inputted to an input terminal 3, a relay 9 is excited by means of a transistor 5 so as to supply lamp drive current to a lamp 13 and the lamp 13 is lightened, while the lamp drive current is converted into a minute detection voltage Vb, by means of a resistor 10, and then, it is determined where the detection voltage Vb, is included among a normal range, an overload range, and a disconnection range by means of a detection circuit 11. Therefore, it can be detected whether the lamp 13 is normally lighted or not, whether the lamp 13 is disconnected or not, or whether a wrong rating is used for the lamp 13 or not, even when a resistance value of the resistor 10 is reduced greatly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp lighting system for lighting a headlamp of an automobile, and more particularly to a lamp lighting for protecting a drive circuit side by detecting when a lamp exceeding a rating is attached. About the system.

[0002]

2. Description of the Related Art A headlamp lighting circuit as shown in FIG. 3 is known as a conventional lamp lighting circuit.

A headlight lighting circuit 101 shown in FIG.
Changes the power supply voltage supplied from the battery 103 when the switch 102 is turned on.
4 to turn it on, and to control the headlight circuit 10 by the two disconnection detection circuits 105 and 106.
Then, it is detected whether or not each of the headlights 107 and 108 that constitutes 4 is disconnected. When it is detected that any one of the headlights 107 and 108 is disconnected, the logic of the signal output from each of the disconnection detection circuits 105 and 106 by the OR circuit 111 including the two diodes 109 and 110. By taking the sum, the relay circuit 112 is driven, and the lamps 114 and 115 of the auxiliary lamp circuit 113 are turned on. With this, two diodes 116,
The OR circuit 118 configured by 117 performs a logical OR operation of the signals output from the respective disconnection detection circuits 105 and 106 to turn on the warning lamp 119. As described above, when one of the headlights 107 and 108 is disconnected, the disconnection detection circuits 105 and 106 detect the disconnection, turn on the alarm lamp 119, and turn on the lamps 114 and 115 of the auxiliary lamp 113. Turn on to ensure safety.

In this case, as shown in FIG. 4, the disconnection detection circuit 105 has a current / voltage conversion resistor 120 having one end connected to the headlight 107 and the other end grounded, and one end connected to the switch 102. A resistor for load connection 121 connected to the other end of the resistor 121, a grounded emitter, a transistor 122 for disconnection detection having a base connected to one end of the resistor 120, and a switch 102
Is closed, while the power supply voltage is supplied to the collector of the transistor 122 by the resistor 121,
The headlight driving current flowing through the headlight 107 is
To generate a headlight drive voltage according to the headlight drive current, and turn on the transistor 122.

When the headlamp 107 is disconnected and the headlamp drive current stops flowing, the transistor 122 is turned off to output a Hi voltage (disconnection detection signal) from the collector.

The disconnection detecting circuit 106 has the same configuration as the above-described electric wire detecting circuit 105. When the switch 102 is closed, the power supply voltage is supplied to the collector of the transistor 122 by the resistor 121 while the switch 102 is closed. The headlight driving current flowing through the headlight 108 is guided to the resistor 120 to generate a headlight driving voltage corresponding to the headlight driving current, and the transistor 122 is turned on.

When the headlamp 108 is disconnected and the headlamp drive current stops flowing, the transistor 122 is turned off, and a Hi voltage (disconnection detection signal) is output from the collector.

[0008]

However, such a headlight lighting circuit 101 has the following problems.

That is, in such a headlight lighting circuit 101, the headlights 107, 1
08 is supplied to the transistor 122
Must be converted to a headlight drive voltage having a value equal to or higher than the base-emitter voltage V _BE, the value of the resistor 120 cannot be made smaller than a predetermined value.

For this reason, the resistance 1
When the head 20 emits heat and the headlights 107 and 108 are turned on for a long time, the resistor 120 may overheat and ignite.

Further, for some reason, the headlight 10
7 and 108 are short-circuited,
8 is installed, when the overload condition occurs, the resistance 1
There is a problem that the value of the headlight drive current supplied to the resistor 20 and the resistor 120 and the transistor 122 are destroyed.

SUMMARY OF THE INVENTION In view of the above circumstances, according to the present invention, the detection of disconnection of a lamp and the detection of overload are performed simultaneously while preventing elements constituting a circuit from being overheated and destroyed. It is an object of the present invention to provide a lamp lighting system for an automobile that can be used.

According to a second aspect of the present invention, as a basic element, 1
A simple circuit that uses two resistors and two operational amplifiers to simultaneously detect disconnection and overload of a lamp while preventing overheating and destruction of elements that make up the circuit. It is an object of the present invention to provide an automotive lamp lighting system which can suppress an increase in the cost of the entire system.

[0014]

In order to achieve the above object, according to the present invention, there is provided a lamp lighting system for driving a lamp while monitoring the occurrence of abnormality and lighting the lamp. Current-voltage conversion means for converting the flowing lamp drive current to a minute detection voltage; and a detection circuit for detecting a disconnection or an overload when the detection voltage output from the current-voltage conversion means is out of a predetermined voltage range. And a detecting means for generating.

According to a second aspect of the present invention, in the lamp lighting system according to the first aspect, the current-voltage conversion means includes:
A detection voltage generating circuit configured to divide a power supply voltage to generate a disconnection detection reference voltage and an overload reference voltage; However, when the disconnection detection reference voltage is higher than the disconnection detection operational amplifier that outputs a disconnection detection signal, and when the minute detection voltage generated by the resistor is lower than the overload reference voltage Is characterized by comprising a detection circuit including an overload detection operational amplifier that outputs an overload detection signal.

According to the first aspect of the present invention, in a vehicle lamp lighting system for driving a lamp of an automobile or the like and lighting the same while detecting whether the lamp of the automobile is abnormal or not, A lamp driving current flowing through the lamp is converted into a minute detection voltage by a detector, and when this detection voltage deviates from a predetermined voltage range, this is detected by a detection circuit, and a disconnection detection signal or an overvoltage is detected. By generating the load detection signal,
The detection of disconnection of the lamp and the detection of overload are performed at the same time while preventing elements and the like constituting the circuit from being overheated and destroyed.

According to a second aspect of the present invention, a simple circuit is provided by using a resistor as the current-voltage converter and using two operational amplifiers as the detection circuit.
The detection of disconnection of the lamp and the detection of overload are simultaneously performed while preventing overheating of elements constituting the circuit and preventing the elements from being destroyed, thereby suppressing an increase in the cost of the entire system.

[0018]

FIG. 1 is a circuit diagram showing an embodiment of an automotive lamp lighting system according to the present invention.

The vehicle lamp lighting system 1 shown in FIG. 1 has a battery 2 which is grounded on the negative terminal side and outputs a power supply voltage (battery voltage) from a positive terminal to supply each part of the vehicle, and a headlight drive switch output. , An input terminal 3, a signal transmitting resistor 4 having one end connected to the input terminal 3, a relay driving transistor 5 having a base connected to the other end of the resistor 4, and an emitter grounded; One end is connected to the positive terminal of the battery 2 and the other end is connected to the collector of the transistor 5. When the coil 6 is not excited, the common terminal 7 c and the terminal 7
b and a relay 9 having a contact piece 8 connecting the common terminal 7c and the terminal 7a when the coil 6 is excited.
One end is connected to the terminal 7 a of the relay 9, and the other end is connected to one end of the lamp 13.
And

Further, an automobile lamp lighting system 1
Indicates that the ground terminal 11d is grounded and the power supply voltage input terminal 11
a is connected to one end of a resistor 10 and a detection voltage input terminal 11
b is connected to the other end of the resistor 10 and detects whether the voltage (detection voltage V _b ) obtained at the other end of the resistor 10 is out of a preset voltage range, and
c, a detection circuit 11 for outputting a signal (a lighting signal, a disconnection detection signal, or an overload detection signal) corresponding to the detection result from c.
And the input terminal 12a is connected to the output terminal 11c of the detection circuit 11, the output terminal 12b is connected to the base of the transistor 5, and according to the signal output from the detection circuit 11,
A CPU circuit 12 for performing drive processing of the transistor 5, disconnection display processing, overload display processing, and the like.

In this case, as shown in FIG. 2, the detection circuit 11 includes three resistors 14, 15, and 16 connected in series, and is inserted between the power supply voltage input terminal 11a and the ground point. A reference voltage generating circuit 17 for dividing the power supply voltage input to the power supply voltage input terminal 11a to generate an overload detection reference voltage V _SOV and a disconnection detection reference voltage V _SOP (V _SOV <V _SOP ); Input terminal is power supply voltage input terminal 1
1a, an inverting input terminal is connected to a connection point between the resistor 14 and the resistor 15, and a non-inverting input terminal is connected to the detection voltage input terminal 11b.
A power input terminal is connected to the power supply voltage input terminal 11a, a non-inverting input terminal is connected to a connection point between the resistors 15 and 16, and an inverting input terminal is connected to the detection voltage input terminal 11b. An amplifier 19 and an LED element 20 whose anode is connected to the output terminal of the operational amplifier 19 and which is turned on when an overload detection signal is output from the operational amplifier 19 to indicate that the load is overloaded are provided. .

When the lamp lighting switch (not shown) is turned on and the headlight driving switch output is input to the input terminal 3, the transistor 9 excites the relay 9 and the lamp 13 drives the lamp 13. When a current is supplied, the lamp is turned on, the lamp driving current is converted into a minute detection voltage _Vb by the resistor 10, and the detection circuit 11 controls the detection voltage _Vb to be within a normal range, an overload range, and a disconnection range. It is determined which one is included.

At this time, if the detection voltage _Vb is higher than the overload detection reference voltage V _SOV output from the reference voltage generation circuit 17 and lower than the disconnection detection reference voltage V _SOP , this is determined by the operational amplifiers 18 and 19. Detected, lamp 1
A lighting signal (Lo signal output from each of the operational amplifiers 18 and 19) indicating that the light emitting device 3 is lighting normally is output, and this is detected by the CPU circuit 12,
The lighting of the lamp 13 is maintained until a lighting maintaining voltage is supplied from the CPU circuit 12 to the base of the transistor 5 and a lamp extinguishing switch (not shown) is turned on.

The detection voltage _Vb is equal to the reference voltage generation circuit 1
If the voltage is lower than the overload detection reference voltage V _SOV output from 7, the operational amplifier 19 detects this and outputs an overload detection signal (Hi signal). This gives L
The driver or the like is informed that the ED element 20 is driven to be lit, and that the overload state is caused due to a difference in the rating of the lamp 13 or the like. In parallel with this operation,
The circuit 12 detects that an overload detection signal is output from the detection circuit 11, and stops supplying the lighting maintenance voltage to the transistor 5, stops the lighting of the lamp 13, and displays an overload display. Processing is performed.

If the detection voltage _Vb is higher than the disconnection detection reference voltage _VSOP output from the reference voltage generation circuit 17, this is detected by the operational amplifier 18, and a disconnection detection signal (Hi signal) is output. At the same time, this is detected by the CPU circuit 12, and processing such as disconnection detection display (disconnection detection display) is performed, and this is reported to the driver or the like.

Thus, in this embodiment,
While the overload detection reference voltage V _SOV and the disconnection detection reference voltage V _SOP are generated by the reference voltage generation circuit 17 of the detection circuit 11, the lamp driving current is converted into a minute detection voltage V _b by the resistor 10 having a small resistance value. Two operational amplifiers constituting the detection circuit 11, that is, an operational amplifier 1 that outputs a Hi signal or a Lo signal when the voltage difference between the inverting input terminal and the non-inverting input terminal is about several μV or several mV.
Whether the detected voltage _Vb is included in the normal range, the overload range, or the disconnection range is determined by 8 and 19. Therefore, even if the resistance value of the resistor 10 is extremely small, the lamp 13 Is normally lit, disconnected, the rating of the lamp 13 is different, etc., so that the resistor 10 and the like constituting the circuit are not overheated and the calculation is performed. Amplifier 1
While preventing damage to 8, 19, etc., the lamp 1
3 and the overload detection can be performed simultaneously.

Further, in this embodiment, the disconnection detection of the lamp 13 and the overload detection can be simultaneously performed by a simple circuit using one resistor 10 and two operational amplifiers 18 and 19 as basic elements. Since this is performed, the disconnection detection of the lamp 13 and the overload detection can be simultaneously performed while suppressing an increase in the cost of the entire system.

In this embodiment, when the lamp 13 is overloaded due to the fact that a lamp having a rating different from the preset rating is mounted as the lamp 13, the CPU circuit 12 detects this, stops driving the transistor 5, and stops the lighting of the lamp 13. Therefore, when the lamp 13 having a rating other than the rated one is mounted, the lighting of the lamp 13 is immediately stopped. In this case, no extra load is applied to the circuit.

Also, in the above-described embodiment, the vehicle lamp lighting system according to the present invention has been described by taking as an example a case where the overload protection circuit is not used. When an overload is detected by the CPU circuit 12 together with the load protection circuit,
The overload protection circuit may be operated to protect a resistor, a fuse, an electric wire, or the like, or to prevent ignition or the like.

[0030]

As described above, according to the present invention, according to the first aspect, detection of disconnection of a lamp and detection of overload are simultaneously performed while preventing overheating and destruction of elements constituting a circuit. be able to.

According to the second aspect, as the basic element, 1
With a simple circuit using one resistor and two operational amplifiers, it is possible to simultaneously detect lamp disconnection and overload while preventing overheating and destruction of elements that constitute the circuit, As a result, an increase in the cost of the entire system can be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of an automotive lamp lighting system according to the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration example of a detection circuit shown in FIG. 1;

FIG. 3 is a circuit diagram showing an example of a conventionally known headlight lighting circuit.

FIG. 4 is a circuit diagram showing a detailed configuration example of a disconnection detection circuit shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lamp lighting system for vehicles 2 Battery 3 Input terminal 4 Resistance 5 Transistor 6 Coil 7 Relay 7a, 7b Terminal 7c Common terminal 8 Contact piece 9 Relay 10 Resistance (current-voltage converter) 11 Detection circuit 11a Power supply voltage input terminal 11b Detection voltage Input terminal 11c Output terminal 11d Ground terminal 12 CPU circuit 12a Input terminal 12b Output terminal 13 Lamp 14, 15, 16 Resistance 17 Reference voltage generation circuit 18, 19 Operational amplifier 20 LED element

Claims (2)

[Claims] 1. A lamp lighting system for driving a lamp while monitoring the occurrence of an abnormality in a lamp and lighting the lamp, current-voltage conversion means for converting a lamp driving current flowing through the lamp into a minute detection voltage, A lamp lighting system comprising: a detection unit that generates a disconnection detection signal or an overload detection signal when a detection voltage output from a current-voltage conversion unit is out of a predetermined voltage range. 2. The lamp lighting system according to claim 1, wherein the current-to-voltage conversion unit is formed of a resistor, and the detection unit divides a power supply voltage to obtain a disconnection detection reference voltage and an overload reference. A reference voltage generation circuit that generates a voltage, and if the minute detection voltage generated by the resistor is higher than the disconnection detection reference voltage, a disconnection detection operational amplifier that outputs a disconnection detection signal; A detection circuit including: an overload detection operational amplifier that outputs an overload detection signal when the minute detection voltage generated by the resistor is lower than the overload reference voltage. Lamp lighting system characterized by being performed.