JPH04293630A - Headlight for vehicle - Google Patents

Abstract

PURPOSE:To prevent the output of the high voltage when no discharge lamp bulb is installed and make a device lightweight and small-sized. CONSTITUTION:A connection detecting circuit 25 detects whether bases 2, 3 of a conductor and the bulb insertion port 4 of the conductor are electrically connected or not, if it detects that the bulb insertion port 4 and the bases 2, 3 are not connected, it outputs a break-off signal to a drive control circuit 23, and the drive control circuit 23 cuts off the voltage applied to a discharge lamp bulb 33.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a vehicle headlamp.
In particular, the present invention relates to a vehicle headlamp that uses a discharge lamp as a light source.

0002

2. Description of the Related Art It is known to use a discharge lamp as a light source in order to obtain a vehicle headlamp that is small and emits a large amount of light. An example of such a device is shown in FIG. 5.

[0003] In FIG. 5, 50 is a battery. 5
Reference numeral 5 denotes a switch installed in the vehicle interior, which is turned on and off by the driver. 54 is a discharge lamp. When a high frequency voltage is applied to the discharge lamp 54, a discharge occurs between the electrodes a and b, and light is emitted.

A DC/DC converter 51 converts the DC voltage output from the battery 50 into a DC voltage of a constant value when the switch 55 is conductive. 52 is a DC/AC inverter, which converts the DC voltage output from the DC/DC converter 51 into a high frequency voltage. A high voltage generating circuit 53 generates a high voltage pulse when the discharge lamp 54 starts to be driven.

Next, the operation will be explained. The DC voltage output from the battery 50 is converted into a predetermined voltage by the DC/DC converter 51 and then input to the DC/AC inverter 52 . The DC/AC inverter 52 converts DC voltage into high frequency voltage. The high frequency voltage is then input to the high voltage generation circuit 53, and the high voltage generation circuit 53 outputs a pulse signal. This pulse signal is converted into a high voltage pulse by a transformer 56. As a result, terminal A,
A high voltage pulse is applied between electrodes B, causing dielectric breakdown between electrodes a and b inside the discharge lamp 54, and the discharge lamp 54 is turned on.

After the discharge lamp 54 starts lighting, the high voltage pulse stops, and a high frequency voltage is applied to the discharge lamp 54 by the DC/AC inverter 52.
remains lit.

[0007]

[Problem to be solved by the invention] In the above device,
The voltage of the high voltage pulse generated by the high voltage generation circuit 53 is about ten [kV], and the voltage value of the high frequency voltage output from the DC/AC inverter 52 is about 80 [V]. Therefore, when a bulb (not shown) is removed from the lighting device due to bulb replacement, etc., that is, when terminals A and B are open, and this device is operating, the insulation part of the circuit wiring or the inverter may be damaged. A high voltage is applied to 52 circuit elements and the like. Therefore, the withstand pressure of these parts must be increased, resulting in an increase in size and weight. Furthermore, since materials and elements with high withstand voltage are expensive, there is a problem in that the cost of the device increases.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a lighting device that prevents high voltage from being applied when a discharge lamp bulb is not installed.

[0009]

[Means for Solving the Problems] The present invention is a vehicle headlamp comprising a discharge lamp bulb, a power supply, a bulb insertion port, a connection detection means, and a drive control circuit, wherein the discharge lamp bulb is , which discharges by applying a voltage between the electrodes, and has a cap made of a conductor, and the power supply supplies the voltage to be applied between the electrodes of the discharge lamp bulb. The bulb insertion port is made of a conductor, into which the discharge lamp bulb is mounted, and when the discharge lamp bulb is mounted, the bulb insertion port is electrically connected to the cap of the discharge lamp bulb. , the connection detection means is
When it is detected that the base of the discharge lamp bulb and the bulb insertion port are not electrically connected, the control circuit outputs a detachment signal, and when the detachment signal is input, the control circuit outputs the disconnection signal. This shuts off the power supplied to the discharge lamp bulb.

0010

According to the above structure, when the discharge lamp bulb is attached to, for example, the bulb insertion opening formed in the reflector, the base of the discharge lamp bulb and the bulb insertion opening are electrically connected. Then, the connection detection means detects that the cap and the valve insertion port are electrically connected, and no disconnection signal is output. Therefore, power can be supplied to the discharge lamp bulb.

On the other hand, when the discharge lamp bulb is not attached to the bulb insertion port, the cap and the bulb insertion port do not come into contact with each other, so that they are electrically opened. Then, the connection detection means detects that the cap and the valve insertion port are not electrically connected, and outputs a disconnection signal. The detachment signal is input to the drive control means. Then, the power to the discharge lamp is cut off by the drive control means.

0012

Embodiment An embodiment of the present invention will be described based on FIGS. 1 to 4. 1 and 2 are perspective views showing a discharge lamp bulb, and FIGS. 3 and 4 are circuit diagrams of this embodiment. In FIG. 1, 1 is a discharge lamp, and 5 is a plug made of an insulator such as resin. The discharge lamp 1 is fixed to one bottom surface 5a of a cylindrical plug 5 by a lead wire 31 and a lead wire 32 in such a direction that the longitudinal direction of the discharge lamp 1 and the axial direction of the plug 5 coincide.

Reference numerals 2 and 3 denote bases, each of which is made of semi-circular metal, and the bases 2 and 3 are electrically insulated from each other. Further, the caps 2 and 3 are fixed to the side surface of the plug 5 such that the surfaces formed by the caps 2 and 3 are perpendicular to the axial direction of the plug 5.

Wirings 10, 11, 12, and 13 are attached to the bottom surface 5b of the plug 5. Wiring 10,1
1, 12, and 13 are a lead wire 31, a lead wire 32, and a cap 2, respectively, passing through the inside of the plug 5 from the bottom surface 5b.
, and is connected to the base 3. And the wiring 10,
11, 12, and 13 are connected to a circuit described later. Note that a discharge lamp bulb 33 is constituted by the discharge lamp 1, the plug 5, the caps 2 and 3, the lead wires 31 and 32, and the wirings 10, 11, 12, and 13.

Reference numeral 6 denotes a parabolic reflecting plate, which is made of metal or mirror-coated resin. A metal bulb insertion opening 4 is provided at the bottom of the paraboloid of the reflector 6.
is formed. The valve insertion port 4 has a circular shape with a diameter equal to the diameter of the plug 5. As shown in FIG. 2, when the discharge lamp bulb 33 is inserted into the bulb insertion port 4 of the reflector plate 6, the plug 5 and the bulb insertion port 4 fit together, and the bases 2 and 3 come into contact with the bulb insertion port 4. .

Next, FIG. 3 shows a circuit diagram of this embodiment. In FIG. 3, the discharge lamp 1 is connected to a drive control circuit 23 as a drive control means through wirings 10 and 11. The drive control circuit 23 controls supply/cutoff of power to the discharge lamp 1. 25 is a connection detection circuit as connection detection means. The base 2 is connected to the connection detection circuit 2 by the wiring 12.
5 and an input terminal of the exclusive NOR circuit 6 and one end of the resistor 14. Also, the base 3 is the wiring 1
3, it is connected to the input terminal of the exclusive NOR circuit 6 and one end of the resistor 15. And resistance 1
The other end of resistor 15 is connected to a power supply +V of 5 [V], and the other end of resistor 15 is connected to ground.

The output terminal of the exclusive NOR circuit 16 is input to the base of a transistor 19 via a resistor 17. The resistor 18 is a voltage holding resistor. The collector of the transistor 19 is connected to the power supply +V via the coil of the relay 20 and the resistor 21. Further, the emitter of the transistor 19 is connected to ground. One terminal of the contacts of the relay 20 is connected to the power supply +V, and the other terminal is connected to the drive control circuit 23.

24 is a battery. Reference numeral 22 denotes a switch installed in the vehicle interior, which is turned on and off by the driver. One terminal of the switch 22 is connected to the battery 24, and the other terminal is connected to the drive control circuit.

FIG. 4 shows the configuration of the drive control circuit 23. 4
7 is an AND circuit, one input terminal 47a of the AND circuit 47 is connected to the contact of the relay 20, and the other input terminal 47b is connected to the switch 22. 41
is a DC/DC converter, which is connected to the output terminal of the AND circuit 47. The DC/AD converter 41 converts an input DC voltage into a DC voltage of a constant value.

42 is a DC/AC inverter;
Converts the DC voltage output from the /DC converter 41 into a high frequency voltage. 43 is a high voltage generation circuit, which causes the transformer 46 to generate high voltage pulses. The output terminals of the DC/AC inverter 42 are connected to the wirings 10 and 11.

Next, the operation of this embodiment will be explained based on FIG. When the discharge lamp bulb 33 is inserted into the bulb insertion port 4 of the reflector plate 6, the caps 2 and 3 come into contact with the bulb insertion port 4, and the bulb insertion port 4 and the caps 2, 3 are in contact with the bulb insertion port 4.
are electrically connected. Therefore, the wiring 12 connected to the base 2 and the wiring 13 connected to the base 13 have the same potential, and the same potential is input to the input terminal of the exclusive NOR circuit 16. Therefore, the output of the exclusive NOR circuit 16 is turned on, and the transistor 19 is turned on.

As a result, current flows from the power supply +V to the resistor 21 and the coil of the relay 20, and the relay 20 becomes conductive. Then, the AND circuit 4 is connected to the power supply +V.
An ON voltage signal is input to the input terminal 47 of No. 7. When the switch 22 is turned on in this state, AND
Since the ON voltage signal is also input to the input terminal 47b of the circuit 47, the output of the AND circuit 47 is also in the ON state. As a result, DC/DC converter 41, DC/AC inverter 42, and high voltage generation circuit 43 operate.

That is, the DC voltage output from the output terminal of the AND circuit 47 is converted into a predetermined voltage by the DC/DC converter 41 and then input to the DC/AC inverter 42 . The DC/AC inverter 42 converts DC voltage into high frequency voltage. The high frequency voltage is then input to the high voltage generation circuit 43, and the high voltage generation circuit 43 outputs a pulse signal. This pulse signal is converted into a high voltage pulse by a transformer 46.

As a result, a high voltage pulse is applied between the wirings 10 and 11, dielectric breakdown occurs inside the discharge lamp 1, and the discharge lamp 1 is turned on. After the discharge lamp 1 starts lighting, the high voltage pulse stops and the DC/AC inverter 4
2 applies a high frequency voltage to the discharge lamp 1, and the discharge lamp 1
remains lit.

On the other hand, when the discharge lamp bulb 33 is removed from the reflector plate 6, the bulb insertion opening 4 and the caps 2 and 3 are removed.
are separated, and the valve insertion port 4 and the caps 2 and 3 are electrically cut off. Therefore, since the wiring 12 connected to the base 2 is connected to the power supply +V, a positive potential is generated, and the wiring 13 connected to the base 13 is connected to the ground, so the potential becomes 0. As a result, different potentials are input to the input terminals of the exclusive NOR circuit 16, the output of the exclusive NOR circuit 16 is turned OFF, and the transistor 19 is cut off.

Therefore, no current flows from the power supply +V to the coil of the relay 20, and the relay 20 is cut off, so the AN
An OFF voltage signal is input to the input terminal 47a of the D circuit 47.

Even if the switch 22 is turned on in this state,
The output of the AND circuit 47 is in the OFF state. the result,
DC/DC converter 41, DC/AC inverter 42
, and high voltage generation circuit 43 do not operate.

As described above, according to this embodiment, the two separate caps 2 and 3 are installed in the plug 5 of the discharge lamp bulb 33, and the metal bulb insertion opening 4 and the caps 2 and 3 are in contact with each other. When the caps 2, 3 and the bulb insertion port 4 are not connected, no voltage is applied to the discharge lamp 1 even if the switch 22 is turned on.

Therefore, when the discharge lamp bulb 33 is removed from the reflector plate 6 due to bulb replacement or the like, it is possible to prevent power from being supplied to the discharge lamp bulb, and to prevent excessive voltage from being applied to the circuit elements. The effect is that it can be prevented. As a result, there is no need to use insulating materials with high voltage resistance for circuit elements, etc., and the device can be made lighter and smaller.

In this embodiment, the cap of the discharge lamp bulb 33 is divided into two parts, the bulb insertion port is made of annular metal, and it is detected whether or not the cap and the bulb insertion port are electrically connected. However, it is not limited to this. That is, the cap may be annular, and the valve insertion port may be divided into a plurality of parts and connected to the circuit. Alternatively, the cap and the valve insertion port may be connected to the wiring 12 and the wiring 13, respectively, without dividing the cap and the valve insertion port.

[0031]

[Effects of the Invention] As explained above, according to the present invention,
When a discharge lamp bulb is inserted into a bulb insertion port made of a conductor, the bulb insertion port and the cap of the discharge lamp bulb are electrically connected, and the bulb insertion port and the cap are not electrically connected. Sometimes the power supplied to the discharge lamp bulb was cut off.

Therefore, when the discharge lamp bulb is removed from the bulb insertion port, it is possible to prevent power from being erroneously supplied to the discharge lamp bulb, and it is possible to prevent excessive voltage from being applied to the circuit elements. As a result, there is no need to use insulating materials for circuit elements, wiring, etc., and the device can be made lighter and smaller.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a discharge lamp bulb 33 of an embodiment.

FIG. 2 is a perspective view showing the discharge lamp bulb 33 of the embodiment.

FIG. 3 is a circuit diagram showing an embodiment.

FIG. 4 is a circuit diagram showing a drive control circuit 23 of the embodiment.

FIG. 5 is a circuit diagram showing a conventional example.

[Explanation of symbols]

2 Base 3 Base 4 Valve insertion port 33 Discharge lamp bulb 25 Connection detection circuit 23 Drive control circuit

Claims (1)

[Claims] 1. A discharge lamp bulb comprising a discharge lamp bulb, a power supply, a bulb insertion port, a connection detection means, and a drive control circuit, wherein the discharge lamp bulb discharges by applying a voltage between electrodes. and has a base made of a conductor,
The power supply supplies a voltage to be applied between the electrodes of the discharge lamp bulb, the bulb insertion port is made of a conductor, and the discharge lamp bulb is attached to the bulb insertion port. When mounted, it is electrically connected to the cap of the discharge lamp bulb, and the connection detection means detects that the cap of the discharge lamp bulb and the bulb insertion port are not electrically connected. When the withdrawal signal is input, the control circuit outputs a withdrawal signal, and the control circuit cuts off power supplied to the discharge lamp bulb when the withdrawal signal is input.