JPH0617099B2 - Headlight circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a headlight circuit having a disconnection detection circuit for detecting disconnection of two sets of headlamps.

<Prior art> In automobiles, it is difficult to check the lighting status of various lights such as brake lights and turn signals from the interior of the vehicle.Therefore, an indicator circuit for detecting filament breakage should be incorporated. There is. A CS register is generally used as a means for detecting such filament breakage.

By the way, in order to improve the visibility of the vehicle at dusk,
When traveling with the sidelights lit, for example, in cloudy weather, there may be a situation in which the amount of light is insufficient for the sidelights but the burden on the battery for the headlights becomes excessive. For such a case, dimming lighting traveling in which the voltage to the headlight is appropriately limited has been proposed.

<Problems to be Solved by the Invention> On the other hand, the lighting state of the headlight can be relatively easily known from the driver's seat by the light distribution pattern at night,
In the dimmed state described above, the lighting status cannot be known from the driver's seat, so it is preferable to provide the headlamp with the disconnection detection circuit as well as the braking light and the direction indicator light. However,
Since the above-mentioned CS register needs to flow a load current at the same time when the filament is energized, it has an inconvenience such as an increase in power consumption and heat generation, and is applied to a headlamp that continuously energizes a relatively large current. Not suitable for.

The present invention has been devised to address such an inconvenience, and its main purpose is to disconnect a plurality of headlamps in a dimmed lighting state without increasing power consumption and generating heat. It is to provide a headlight circuit including a circuit capable of detecting

[Configuration of the Invention] <Means for Solving the Problems> According to the present invention, an object of the present invention is to provide a dimming lighting circuit having switch means that is intermittently operated in conjunction with a lighting switch, the lighting switch, and the lighting switch. A headlight circuit having two sets of resistance light emitters connected to a power source via a light lighting circuit and a disconnection detection circuit for detecting disconnection of the two sets of resistance light emitters, wherein the two sets Of the resistance light emitters are connected in series to a power source, and the disconnection detection circuit detects the disconnection state of each resistance light emitter based on the voltage value at the intermediate point of the two sets of resistance light emitters. It is achieved by providing a headlight circuit characterized by:

<Operation> As described above, if the resistance light-emitting body composed of two sets of filaments and the like is connected in series to the power supply, since a voltage of 1/2 of the power supply voltage acts on each, the headlamp is It will be dimmed and turned on. The voltage acting on the intermediate point of these two sets of headlights is 1/2 of the power supply voltage when both are lit, and 0 when one set on the positive side of the battery is disconnected, If one set on the negative side of is disconnected, the power supply voltage itself will act.

<Embodiment> Hereinafter, the present invention will be described in detail with reference to the accompanying drawings with reference to specific embodiments.

FIG. 1 shows an illumination circuit of a headlamp to which the present invention is applied. This circuit includes a lighting relay LTR, which operates intermittently according to the connection / disconnection status of the contacts of the lighting switch LTS, a dimmer relay DMR, and two dimming relays RL1 and RL2 incorporated in the circuit board CB, which serve as a load. To control the flickering of the lights,
A circuit 1 for detecting disconnection of the high beam side filament at the time of dimming lighting is included in the circuit for controlling the dimming lighting of the high beam in the twilight state.

The lighting switch LTS is a multiple-type switch having three positions of an off position, a side lamp lighting position, and a headlight lighting position, and a common terminal of one switch S1 with respect to the positive electrode + B of the vehicle battery, The side light S for the earth line connected to the negative electrode of the vehicle battery
The side lamp lighting terminal and the headlight lighting terminal are connected to each other via the filament of ML. The common terminal of the other switch S2 is connected to the plus electrode + B via the coil of the lighting relay LTR, and the headlamp lighting terminal is connected to the ground line. As a result, when the lighting switch LTS is set to the vehicle width light lighting position or the headlight lighting position, the vehicle width light SML is turned on, and when the lighting switch LTS is set to the headlight lighting position, the coil of the lighting relay LTR is excited. ing.

The filaments of the left and right low beams LLO and RLO and the positive terminal of the coil of the dimmer relay DMR are connected in parallel to one terminal of the excitation-time closed contact of the lighting relay LTR. And both left and right low beams LLO and RL
The positive terminal of the O filament is connected to the normally closed terminals of both dimming relays RL1 and RL2 via the E terminal and I terminal of the circuit board CB.

The other terminal of the lighting relay LTR, which is closed when energized, is connected to the plus electrode + B, and both left and right low beams LL are connected.
The negative terminals of the filaments of O and RLO are directly connected to the ground line.

The minus terminal of the coil of the dimmer relay DMR is connected to the ground line via the passing switch PSG and the high / low changeover switch HLS which are connected in parallel with each other.

The passing switch PSG is connected in parallel between the common terminal on the other side S2 of the lighting switch LTS and the headlamp lighting terminal, and between the high terminal and the common terminal of the high / low changeover switch HLS in parallel. The coils of the lighting relay LTR and the dimmer relay DMR can be excited regardless of the position of the high / low changeover switch HLS.

One ends of the filaments of the left and right high beams LHI and RHI are respectively connected to the common terminals of the dimming relays RL1 and RL2 via the C and D terminals of the circuit board CB. And, one of the dimming relays RL1 has a closed terminal when excited.
The minus line 0V is connected to the earth line via the H terminal of the circuit board CB, and the other excitation light-closed terminal of the dimming relay RL2 is connected to the plus electrode + B via the K terminal of the circuit board CB.

The other ends of the filaments of the left and right high beams LHI and RHI are connected to each other and the dimmer relay DM
It is connected to the earth line via a closed terminal when R is excited. Further, the connecting portions between the other ends of the filaments of the left and right high beams LHI and RHI are connected to the disconnection detection circuit 1 described later via the F terminal of the circuit board CB.

In this way, the filaments of both high beam LHI and RHI are connected in parallel to the dimmer relay DMR via the normally closed terminals of both dimming relays RL1 and RL2, and the excitation of both dimming relays RL1 and RL2 is performed. It is connected in series between both poles of the battery power supply via the time-closed terminal. As a result, when the coils of both dimming relays RL1 and RL2 are in the excited state, both high beams LHI and RHI are dimmed, and when in the degaussed state, four lamps LHI and RHI.
LLO and RLO are connected in parallel to the power supply line, and each of them flashes in response to the operation of the lighting relay LTR and the dimmer relay DMR.

For the circuit board CB in which the control circuit is incorporated, connect the B terminal to the positive electrode + B of the on-vehicle battery via the IG contact of the ignition switch and set the negative electrode to H
The power supply voltage is supplied by connecting the terminals. And the B terminal is a plus line + via the diode D5.
It is connected to 12V, and the H terminal is a minus line 0V.
Is directly connected to. A load resistor R7 and a stabilizing capacitor C1 are connected in parallel between the plus and minus voltage lines + 12V and 0V.

The other terminal of the parking brake switch PKB, one end of which is connected to the ground line, is connected to the A terminal of the circuit board CB. The J terminal of the circuit board CB has the other terminal of the brake fluid level switch BFL whose one end is connected to the ground line and the filament of the indicator lamp IL whose one end is connected to the plus electrode + B of the vehicle battery. The ends are connected.

A resistor R6 and a diode D2 are connected in series between the A terminal and the plus line + 12V. The A terminal and the J terminal are connected via a diode D6. As a result, the indicator lamp IL is lit when either the parking brake switch PKB or the brake fluid level switch BFL is closed.

The intermediate portion between the resistor R6 and the diode D2 is connected to the base of the transistor T2 through the Zener diode ZD2, the resistor R5 and the diode D8 which are connected in series. In this transistor T2, a resistor R4 and a capacitor C3 are connected in parallel between its base and a minus line 0V, its emitter is directly connected to the minus line 0V, and two dimming relays RL1 and RL are connected in parallel.
The collector is connected to one end of the second coil. The other ends of the coils of these two dimming relays RL1 and RL2 are connected in parallel to the collector of the transistor T1 of the circuit for controlling the two dimming relays RL1 and RL2 in response to the operation of the lighting switch LTS. There is.
A diode D4 for eliminating the counter electromotive force of the coils is connected in parallel to both coils.

In order to maintain the conduction of the transistor T2, a self-holding circuit by the transistor T3 is built. The emitter of the transistor T3 is connected to the plus line + 12V via the Zener diode ZD3, and the collector thereof is connected to the base of the transistor T2 via the resistor R8 and the diode D7 connected in series. The base of the transistor T3 is connected to the plus line + 12V via a capacitor C4 and a resistor R9 connected in series, and a resistor R10 connected in parallel with the capacitor C4. An intermediate portion between the capacitor C4 and the resistor R9 is connected to the collector of the transistor T2 via the resistor R11 and the diode D3 which are connected in series.

The other end of the coils of both dimming relays RL1 and RL2 is connected to its collector, and the transistor T1 has a plus line +
The emitter is directly connected to 12V, and the base is connected to the plus line + 12V through the resistor R3 and the capacitor C2 which are connected in parallel, and the resistor R1.
Is connected to the minus line 0V via.

The collector of the transistor T4 is connected to the connection node between the base of the transistor T1 and the resistor R1. The emitter of the transistor T4 is directly connected to the plus line + 12V, and the base of the transistor T4 is connected to the plus line + 12V via the resistor R12 and the capacitor C5 connected in parallel, and the zener diode ZD1 connected in series. Is connected to the G terminal of the circuit board CB via the resistor R2 and the diode D1. The intermediate portion between the resistor R2 and the diode D1 is connected to the plus line + 12V via the resistor R13.

The G terminal is connected to the ground line via the lighting switch LTS or the passing switch PSG.

The collector of the transistor T1 is connected to the collector of the transistor T7 via the resistor R15, the collector of the transistor T5 via the resistor R16, and the collector of the transistor T6 via the resistor R21.

The collector of the transistor T7 is connected to the base of the transistor T8 via the Zener diode ZD4. The transistor T8 is connected to the minus line 0V via the resistor R14 and the capacitor C6 which are connected in parallel.
Its base is connected to. Also, the transistor T
8, the emitter is directly connected to the minus line 0V, and the warning lamp W is connected via the L terminal of the circuit board CB.
The collector is connected to one end of the PL filament. The other end of the filament of the warning lamp WPL is connected to the D terminal together with one end of the filament of the left high beam LHI.

The emitter of the transistor T7 is connected to the collector of the transistor T6, and the base of the transistor T7 is connected to the collector of the transistor T5 via the diode D9 and to the minus line 0V via the capacitor C7.

The transistor T5 has its emitter directly connected to the minus line 0V, and its base connected in series with the Zener diode ZD5, the resistor R18, and the diode D1.
0 is connected to the F terminal and is connected to the minus line 0V via the resistor R17 and the capacitor C8 which are connected in parallel.

The transistor T6 has a zener diode ZD6, a resistor R20, and a diode D1 whose emitters are directly connected to the minus line 0V and whose bases are connected in series.
1 is connected to the F terminal via 1 and is connected to the minus line 0V via a resistor R19 and a capacitor C9 which are connected in parallel.

Next, the operating procedure of the above embodiment will be described.

When starting the engine, it is desirable that the electric load be as small as possible. Therefore, in the above circuit, it is stipulated that cranking should be performed with the perking gig brake applied. When the cranking is performed, the headlights do not dim and the high beam LHI is automatically released when the parking brake is released after the engine is started.・ The RHI is dimly lit.

First, when the parking brake switch PKB is closed at the ON position of the ignition switch IG, the current is
From plus line + 12V, resistor R6 to diode D2
Since it flows to the ~ A terminal, the base potential of the transistor T2 becomes low and the transistor T2 does not conduct. If the transistor T2 does not conduct, both dimming relays RL1 and RL
Since the two do not excite together, the headlight will not light unless the lighting relay LTR or dimmer relay DMR is activated. That is, if the parking brake is applied at the time of starting, the headlight will not be dimmed.

Since the parking brake switch PKB is opened when the parking brake is released as a running battery, the current flows from the plus line + 12V to the resistor R6 to the Zener diode ZD2 to the resistor R5 to the diode D8 to the transistor T2.
To the base of the transistor T2, and the transistor T2 becomes conductive.

When transistor T2 becomes conductive, plus line + 12V
From capacitor C4 to resistor R11 to diode D3
A current flows from the transistor T2 to the minus line 0V, and the capacitor C4 is charged. Then, from the plus line + 12V, the Zener diode ZD3, the emitter-base of the transistor T3, the resistor R9, and the capacitor C are connected.
A bias circuit of the transistor T3 in which a current flows to the negative side of 4 is formed, and the transistor T3 becomes conductive.

When transistor T3 turns on, plus line + 12V
From the Zener diode ZD3 to the transistor T3 to the resistor R8 to the base of the diode D7 to the transistor T2, and the transistor T3 and the transistor T3.
Two self-holding circuits are formed. As a result, unless the ignition switch IG is turned off, the conduction state of the transistor T2 is maintained regardless of the operation of the parking brake switch PKB.

On the other hand, when the ignition switch IG is turned on, the emitter of the transistor T1
Since a current flows from the base to the resistor R1 to the minus line 0V and the transistor T1 becomes conductive, the two dimming relays RL1 and RL are combined with the conduction of the transistor T2.
The two coils are both excited, and the closed contact closes when excited. As a result, the K terminal to the other dimming relay RL2 to D terminal to the left high beam LHI to the right high beam RHI to C terminal to the one dimming relay RL1 to the minus line 0V to H terminal are conducted, and both high beams LHI and RLI are connected. Dims and lights.
This state is the lighting relay LT during engine operation.
Continue unless R is activated.

On the other hand, when the lighting switch LTS is set to the headlamp lighting position, the coil of the lighting relay LTR is excited and the closed contacts are closed during excitation, so that the left and right low beams LLO
LO lights up. At the same time, from the plus line + 12V, between the emitter and the base of the transistor T4-Zener diode ZD1-resistor R2-diode D1-G terminal-
A current flows from the lighting switch LTS to the ground line, and the transistor T4 becomes conductive. Transistor T4
Is turned on, the base potential of the transistor T1 rises, and the transistor T1 is turned off. This allows
Both dimming relays RL1 and RL2 are demagnetized, and the dimming lighting circuit for both high beams LHI and RHI disappears.

If the high / low selector switch HLS is set to the high beam position or the passing switch PSG is operated, the coil of the dimmer relay DMR is excited and 4
All lights turn on. The passing switch PSG
Are connected in parallel to the lighting switch LTS and the high / low changeover switch HLS, so that all the lights can be turned on even by operating the passing switch PSG independently.

Next, the function of the disconnection detection circuit 1 at the time of dimming lighting will be described.

Assuming that the voltage of the on-vehicle battery is 12 volts, the two high beam LHI and RHI filaments are connected in series during dimming lighting, so the potential difference across each filament is 6 volts. Therefore, if both filaments are normal, F, which is the midpoint between both filaments,
The voltage at the terminals will be 6 volts. If the left high beam LHI is disconnected, the voltage at the F terminal becomes 0 V,
If the right high beam RHI is broken, the voltage at the F terminal is 1
It will be 2 volts.

Now, if the Zener voltage of one Zener diode ZD5 is set to 9 V and the Zener voltage of the other Zener diode ZD6 is set to 3 V, both Zener diodes ZD5 and ZD6 have currents when the voltage at the F terminal is 0 V. The transistors T5 and T6, which do not flow and whose bases are connected to them, do not conduct together. And the transistor T
Since 6 is not conducting, the transistor T7 connected to its collector side is also not conducting. If the transistor T7 does not become conductive, a current flows from the transistor T1 to the base of the resistor R15 to the Zener diode ZD4 to the transistor T8, so that the transistor T8 becomes conductive and the warning lamp WPL for notifying the disconnection is turned on.

When 6 V is applied to the F terminal, a current flows only through the Zener diode ZD6 set to 3 V, and the transistor T6 becomes conductive. Then, since the transistor T7 is turned on and the transistor T8 is turned off, the warning lamp WP
L is turned off.

When 12V is applied to the F terminal, both Zener diodes ZD
A current flows through 5.ZD6, and the transistors T5 and T6 connected to these conduct together. Then the transistor T
7 is cut off, the transistor T8 is turned on, and the warning lamp WPL is turned on.

In this way, when one of the left and right high beams LHI and RHI is disconnected, the warning lamp WPL is turned on.

[Effects of the Invention]> According to the present invention, the current that normally flows in the circuit for detecting the disconnection is extremely small, so that the element does not generate heat and the power consumption increases unnecessarily. Will not be invited. Therefore, it is possible to cope with a large load, the degree of freedom in arranging the circuit elements is increased, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a control circuit diagram of a headlamp constructed according to the present invention. 1-Disconnection detection circuit LHI / RHI-High beam WPL-Warning lamp CB-Circuit board

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05B 37/03 B 8715-3K

Claims (1)

[Claims] 1. A dimming lighting circuit having a switch means which is intermittently operated in conjunction with a lighting switch, two sets of resistance light-emitting bodies connected to a power source through the lighting switch and the dimming lighting circuit, and 2. A headlight circuit having a disconnection detection circuit for detecting disconnection of a pair of resistance light emitters, wherein the two sets of resistance light emitters are connected in series to a power supply, Is a circuit for detecting a disconnection state of each resistance light emitter based on a voltage value at an intermediate point of the two resistance light emitters.