JPH0143650B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a lighting control circuit that outputs an intermittent signal when the first switch is turned on, and a continuous signal when the second switch is turned on.
This invention relates to a disconnection detection circuit for a vehicle lamp that is powered on and turned on via a switching element that turns on and off.

Turn on one vehicle lamp continuously in a dark manner (hereinafter referred to as
Conventionally, a two-filament bulb with two filaments in one bulb has been used to selectively light in two ways, such as dim lighting (dim lighting) or bright continuous lighting (hereinafter referred to as bright lighting). However, recently, a method has been proposed in which this can be done using an ordinary one-filament sphere.

FIG. 1 shows an example of a vehicle lamp lighting circuit, in which when a first switch, for example a tail lamp switch 1, is turned on, a lighting control circuit, in this case a dimmer circuit 3, is turned on at a frequency of, for example, 100Hz.
An intermittent signal to turn OFF is output, and the PNP transistor 4, which is a switching element, is repeatedly turned ON.
When turned off, the vehicle lamp consisting of one filament bulb, in this case the tail lamp, is dimly lit, and when the second switch, for example stop lamp switch 2, is turned on, a continuous signal of low potential is output from the dimmer circuit 3. output and transistor 4
When turned ON, the tail and stop lamps 5 are lit brightly.

Incidentally, vehicle lamps are extremely important for preventing accidents when the vehicle is running, and therefore great care must be taken to prevent their disconnection. Therefore, a disconnection detection circuit as shown in FIG. 2 has been devised to detect such a disconnection of a vehicle lamp so that the lamp can be quickly replaced. In FIG. 2, 4 and 5 are the same as in FIG. 6 is a charging resistor whose one end is connected to the + power supply via a main switch 7 such as an ignition key, and the other end is grounded via a capacitor 8; 9 is a connection point between the charging resistor 6 and the capacitor 8; The anode is connected to a, and the connection point b between the transistor 4, the tail, and the stop lamp 5
This is a backflow blocking diode whose cathode is connected to the . 10 has a base connected to the connection point a via a resistor 11, and a collector connected to the connection point of the charging resistor 6 and the main switch 7 via a disconnection indicator, here a disconnection indicator lamp 12. , and is an NPN type display driving transistor with its emitter grounded.

In such a disconnection detection circuit, when the switches (switches 1 and 2) that turn on and off the tail and stop lamps 5 are in the OFF state (hereinafter referred to as
When the main switch 7 is turned ON when the transistor 4 is OFF (referred to as the lamp extinguishing operation),
If the tail and stop lamps 5 are not disconnected, the connection point a is grounded through the diode 9 and the tail and stop lamps 5 and has a low potential, the transistor 10 is not turned on, and the disconnection indicator lamp 12 is not lit. If the tail and stop lamps 12 are disconnected, the connection point a will not be grounded via the diode 9 and the tail and stop lamps 5.
Capacitor 5 is charged via resistor 6 and has a high potential. Therefore, the transistor 10 is turned on and the disconnection indicator lamp 12 lights up to indicate that the tail and stop lamps 5 are disconnected. That is, according to such a disconnection detection circuit, disconnection can be detected when the lamp is turned off, in other words, even before the vehicle is running, which is highly effective in preventing accidents.

However, in the above-mentioned disconnection detection circuit, when transistor 4 is turned on with a continuous signal to brightly light lamp 5 (when switch 2 is turned on), transistor 4 is turned on with an intermittent signal to turn lamp 5 on (dark) (when switch 2 is turned on). Unlike when the lamp is turned on (when the switch 1 is turned on) and the transistor 4 is turned off for a short period of time, the capacitor 8 is Once switch 7 is turned on, the battery will only be charged. For this reason, the connection point a reaches a potential sufficient to turn on the transistor 10, and even when the lamp 5 is not disconnected, the disconnection indicating lamp 12 is turned on, resulting in an erroneous display.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and is a vehicle-use device that can prevent erroneous display when the lamp is lit brightly by turning on the switching element that energizes the lamp with a continuous signal. The purpose of the present invention is to provide a lamp disconnection detection circuit.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 5.

FIG. 3 is a diagram showing an embodiment of the disconnection detection circuit for a vehicle lamp according to the present invention, and in the figure, 1 to 12 are the first
It is similar to FIG. 13 has 2 inputs
In the AND circuit, two diodes 13a and 13b
and one resistor 13c. In this case, AND
One of the cathodes of the diodes 13a and 13b, which are the input terminals 13d and 13e of the circuit 13, is connected to the output terminal, that is, the collector, of the display driving transistor 10, and the other is connected to the non-power supply side terminal of the stop lamp switch 2. has been done. Further, both anodes of the diodes 13a and 13b are connected to a resistor 13.
It is connected to the AND circuit output terminal 13f connected to the non-power supply side terminal of the main switch 7 via c.
Reference numeral 14 denotes an NPN type display drive temporary stop transistor, whose base is connected to the AND circuit output terminal 13f via a voltage guarantee diode 15, whose collector is directly connected to the base of the transistor 10, and whose emitter is connected to the ground. has been done. In addition, 1
6, the AND circuit input terminal 13e is not open,
A resistor is inserted between the input terminal 13e and ground so that the potential is either high or low.

Next, the operation of the above-mentioned circuit of the present invention will be explained.
First, when the lamp 5 is turned off, that is, when the transistor 4 is off and the main switch 7 is turned on, if the lamp 5 is not disconnected, the connection point a connects the diode 9 and the lamp 5 (micro filament resistance when the lamp is turned off). Since it is grounded through the wire, its potential is low, the transistor 10 is not turned on, and the disconnection indicator lamp 12 is not lit. If the lamp 5 is disconnected, the connection point a will not be grounded through the diode 9 and the lamp 5 as described above, but will charge the capacitor 8 through the resistor 6 and will have a high potential. Therefore, the transistor 10 is turned on, lighting up the disconnection indicating lamp 12, and indicating that the lamp 5 is disconnected.

Next, when the main switch 7 is in the ON state and the tail lamp switch 1 is turned on, that is, when an intermittent signal as shown in FIG. 4a is applied to the base of the transistor 4, the transistor 4 is turned on and off accordingly. do. Therefore, if lamp 5 is not disconnected, connection point b is also connected to transistor 4.
The high potential and low potential are repeated according to ON and OFF (see FIG. 4c), and the lamp 2 is lit (darkly lit) at a brightness that corresponds to the timing of these repetitions.
Note that the connection point a has a high potential when the connection point b has a high potential and charges the capacitor 8, but the charged charge is transferred to the transistor 4 which repeats ON and OFF.
Since it is discharged through the diode 9 and the lamp 5 when it is OFF, its potential becomes as shown in FIG. On the other hand, if lamp 5 is disconnected, connection point b is ON-
Even when the transistor 4 is repeatedly turned off, it remains at a high potential as shown in FIG. As shown in FIG. 4f, the potential becomes high, the transistor 10 is turned on, and the disconnection indicating lamp 12 is turned on to indicate that the lamp 5 is disconnected.

Further, when the main switch 7 is in the ON state and the stop lamp switch 2 is turned on, that is, when a continuous low potential signal as shown in FIG. 4b is applied to the base of the transistor 4, the transistor 4 is turned on.
Turns on and lamp 5 lights up brightly. At this time, since the connection point b is continuously at a high potential, the connection point a is also at a high potential, and the transistor 10 is turned on to turn on the disconnection indicating lamp 12 in an attempt to cause an erroneous display.
However, if transistor 10 had been OFF until then, that is, tail lamp switch 1
If the disconnection indicating lamp 12 is not lit when the OFF line is ON, then the AND circuit input terminal 13d is at a high potential. Therefore, in this state, stop lamp switch 2 is turned on,
When the AND circuit input terminal 13e also becomes a high potential, the AND circuit output terminal 13f also becomes a high potential, and a display drive temporary stop signal is inputted to the base of the transistor 14 via the diode 15. This turns on the transistor 14 and brings the base of the transistor 10 to a low potential. Therefore, even if the connection point b is continuously at a high potential, the connection point a is at a low potential, the transistor 10 is not turned on, and the disconnection indicating lamp 12 is not turned on, that is, no erroneous display occurs. On the other hand, when the lamp 5 is disconnected, the disconnection indicator lamp 12 lights up as described above, indicating a disconnection, and at this time, the stop lamp switch 2 is turned on.
Then, as before, connection point a becomes high potential, but
The AND circuit input terminal 13d is at a low potential.
Therefore, the AND circuit output terminal 13f also becomes a low potential,
The transistor 14 remains OFF, the transistor 10 remains ON, and the disconnection indicator lamp 12 remains lit. In other words, the stop lamp 2
When turned on, if the disconnection indicator lamp 12 had been lit up until then, the transistor 14 will not be turned on, and if it has not been lit, the transistor 14 will be turned on.
It is something to do. Here, the diode 15
are the diodes 13a, which constitute the AND circuit 13;
The voltage drop of transistor 14 due to the voltage drop of 13b
This prevents the operating point from becoming unstable when OFF.

In the above-described embodiment, a case has been described in which one lamp disconnection is detected using one display driving transistor 10 and one disconnection indicating lamp 12.
As illustrated in FIG. 5, in which the same or corresponding parts as in FIG.
A forward diode 17 is connected between each of them to form an OR circuit, and the transistor 10 is turned on when one of the lamps 5 is disconnected. 10, multiple (5th
It is also possible to detect disconnection of two lamps 5 (in the figure).

Further, in the above embodiment, the lamp 12 is used to indicate the disconnection of the lamp 5, but the present invention is not limited to this, and for example, a light emitting diode or the like may be used.

The first switch, second switch, vehicle lamp, and lighting control circuit are not limited to the tail lamp switch, stop lamp switch, tail, stop lamp, and dimmer circuit, respectively.

As described above, the present invention causes the lighting control circuit to output a continuous signal and turn on the switching element continuously, that is, when the second switch is turned on to brightly light the vehicle lamp, the display driving transistor is turned on. A display drive temporary stop transistor whose base is grounded is provided, so when the vehicle lamp is turned on brightly, even if the vehicle lamp is not disconnected, the display drive transistor is turned ON, that is, the display is driven. This will prevent erroneous display. Moreover, in this case, an AND circuit is provided whose input terminals are the output terminal of the display drive transistor and the lighting control circuit side terminal of the second switch, and the output terminal is connected to the base of the display drive temporary stop transistor. This not only prevents erroneous display, but also allows the display to remain in the same state until the second switch is turned on, ensuring that it is always accurately displayed whether or not the vehicle lamp is disconnected. This has the effect of making things worse.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a vehicle lamp lighting circuit that selectively lights a vehicle lamp using one filament bulb in two ways, and Figure 2 is a diagram showing an example of a vehicle lamp lighting circuit that lights a vehicle lamp using the lighting circuit shown in Figure 1. 3 is a diagram showing an embodiment of the disconnection detection circuit for a vehicle lamp according to the present invention, and FIGS. 4a to 4f are signal waveform diagrams of various parts for explaining the operation of the same circuit. , FIG. 5 is a diagram showing another embodiment of the circuit of the present invention. 1... Tail lamp switch, 2... Stop lamp switch, 3... Dimming circuit, 4... Transistor, 5... Tail, stop lamp, 6...
Charging resistor, 7... Main switch, 8... Capacitor, 9... Backflow blocking diode, 10... Display drive transistor, 11... Resistor, 12...
Disconnection indicator lamp, 13...AND circuit, 13d,
13e...AND circuit input terminal, 13f...AND circuit output terminal, 14...Transistor for temporarily stopping display drive.

Claims (1)

[Claims] 1 Turns on and off according to the output signal of the lighting control circuit, which outputs an intermittent signal when the first switch is turned on, and a continuous signal when the second switch is turned on.
In a vehicle lamp that is turned on by being energized through a switching element that is turned on, a capacitor that can be charged via a charging resistor by turning on a main switch, a connection point between the charging resistor and the capacitor, the switching element and the vehicle A backflow blocking diode is connected between the connection point of the charging lamp and the base is connected to the connection point of the charging resistor and capacitor via a resistor, and the potential of this connection point is turned on when it is above a predetermined value. A display drive transistor that drives a disconnection indicator, an output terminal of this display drive transistor, and a terminal on the lighting control circuit side of the second switch are respectively input terminals, and the signal input to both input terminals is an AND circuit that calculates a logical product and outputs a display drive temporary stop signal; and a display drive temporary circuit that grounds the base of the display drive transistor when the display drive temporary stop signal is input to the base. A disconnection detection circuit for a vehicle lamp, comprising a stop transistor.