JPH0525699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a lighting method and a lighting device for vehicle marker lights such as brake lights.

BACKGROUND OF THE INVENTION Vehicle marker lights that use light emitting diodes as light sources are used in automobile brake lights and the like. This type of brake light is shown in FIG.

The brake lamp 1 is composed of a display device 4 in which a large number of light emitting diodes 2 are mounted on a substrate 3. The light emitting diode 2 is made of a GaAlAs chip and emits red light. The actual brake lamp includes a display device 4 housed in a case (not shown).

Figure 7 shows a conventional lighting circuit 5 for the brake lamp 1.
shows. Brake lamp 1 having light emitting diode 2 is connected to resistors 6 and 7, and brake lamp 1 and resistors 6 and 7 are connected between terminals A and B. The brake lamp 1 consists of three wires connected in parallel, each wire having five light emitting diodes connected in series. A resistor 6 is connected in series to each of the three wires. Further, the resistor 7 is connected in series to the brake lamp 1. The value of the resistor 6 is set so that a uniform current flows through each light emitting diode 2 of the brake lamp 1. The resistor 7 is a limiting resistor for the current flowing through the brake lamp 1. Although not shown, a wiring pattern is formed on the back surface of the substrate 3.

FIGS. 8A and 8B show time charts of voltage and current applied to a conventional lighting circuit, respectively. By stepping on the brake pedal, a switch (not shown) is turned on, and as shown in FIG. is applied to DC voltage Vdc is continuously applied between terminals A and B while the brake pedal is continued to be depressed. As shown in FIG. 8B, when the DC voltage Vdc is applied, each light emitting diode 2 of the brake lamp 1
A current I of approximately the same magnitude flows through the two, and the light emitting diode 2 lights up. The light emitting diode 2 lights up continuously without substantially changing the amount of light emitted during the period when the DC voltage Vdc is applied.

In conventional vehicle marker lights that use filament lamps other than light-emitting diodes, there is a time lag between when power is applied to the lighting circuit (after the brake is pressed) and when the amount of light emitted from the lamp reaches a steady value. . Although this time lag is a small amount of time, for example, about 0.3 seconds, the distance traveled by a vehicle traveling at high speed during the time lag can reach several meters. Therefore, when a preceding vehicle traveling at high speed depresses its brakes, the warning to the following vehicle is delayed by at least a time corresponding to the above-mentioned time lag. On that point, the time lag of a light emitting diode from when a voltage is applied until the amount of light emitted from the lamp reaches a steady value is extremely short, on the order of milliseconds. Vehicle marker lights using diodes have excellent responsiveness when the power is turned on, and have desirable characteristics as marker lights.

Problems to be Solved by the Invention Since the amount of light emitted by the light emitting diode 2 depends on the magnitude of the current, conventionally the current value (hereinafter referred to as the maximum allowable current value) that does not affect the service life even when continuously energized has been set.
The current was passed through the light emitting diode 2 to light the light emitting diode. Note that the maximum allowable current value is, for example, about 30 mA, but this value varies depending on the capacity of the light emitting diode used. Here, it is necessary for vehicle marker lights such as the brake lamp 1 to improve visual stimulation as much as possible when emitting light.

Therefore, in order to meet the above requirements, it is conceivable to further increase the current flowing through the light emitting diode 2 to increase the amount of light emitted. However, if the light emitting diode 2 is continuously energized in excess of the maximum allowable current value, the light emitting diode 2 will be heated to a high temperature due to heat generation. Therefore, the life of the light emitting diode 2 is significantly shortened, and the light emitting efficiency of the light emitting diode 2 is also reduced. Therefore, even if the light emitting diode 2 is turned on at a current exceeding the maximum allowable current value, not only will it not be possible to obtain a large amount of light emitted commensurate with the increase in current, but it will also shorten the lifespan of the light emitting diode and waste power. This will result in an increase.

As described above, with the conventional lighting methods, it has not been possible to turn on the brake lamp 1 with improved visual stimulation. Therefore, in the past, this problem was dealt with by increasing the number of light emitting diodes 2 in order to enhance the visual stimulation of the marker light when it emits light. However, increasing the number of light emitting diodes 2 increases the cost and size of the marker light, which is not desirable. These problems are not limited to brake lights;
There were also problems with other types of vehicle marker lights.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a lighting method and a lighting device for a vehicle marker light, which can enhance visual stimulation when emitting light and illuminate the vehicle marker light.

Means for Solving the Problems The method of lighting a vehicle marker lamp according to the present invention lights up the light emitting diode with high brightness using a large current that exceeds the maximum allowable current value of the light emitting diode when the switch is turned on in conjunction with the operation of the brake pedal. and a step of lighting the light emitting diode with a current below a maximum allowable current value after the light emitting diode is turned on at high brightness and after a certain period of time has elapsed, until the operation of the brake pedal is stopped and the switch is turned off. Consists of. When lighting the light emitting diode with high brightness, the light emitting diode may be lit with high brightness by intermittently flowing a large current exceeding the maximum allowable current value of the light emitting diode when a switch linked to the operation of the brake pedal is turned on.

The lighting device for a vehicle marker lamp according to the present invention includes a switch linked to the operation of a brake pedal, a light emitting diode connected in series to the switch, a resistor connected in series to the light emitting diode, and a resistor connected in parallel. and a timer circuit that is connected to the switch and the control terminal of the switching element and maintains the switching element on by supplying a control signal to the control terminal of the switching element for a certain period of time when the switch is turned on.

Function: The indicator light is lit continuously while the brake pedal is depressed. In order to provide sufficient visual stimulation when lighting, the transistor is turned on and the diode is lit for a certain period of time with a current that exceeds the maximum allowable current. The transistor is then switched off and the diode is lit with a current below the maximum permissible current value until the brake pedal is stopped.

Embodiment A brake lamp lighting method according to an embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 5.
Note that the same parts as in the conventional example shown in FIGS. 6 to 8 are given the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows a lighting circuit 8 as the main part that implements the lighting method according to the present invention. The lighting circuit 8 is
Brake light 1, resistor 6, 7, resistor 9, 10,
Capacitor 11 and field effect transistor 12
Consists of.

As shown in the figure, a brake lamp 1, resistors 6 and 7, and a capacitor 11 and a resistor 10 are connected in parallel between terminals A and B. Further, a resistor 9 is connected in parallel to the capacitor 11. A drain of a field effect transistor 12 is connected between the resistor 6 and the resistor 7. Field effect transistor 12
The gate of is connected between capacitor 11 and resistor 10, and the source is connected to terminal B.

In the above configuration, the operation of the circuit shown in FIG. 1 will be explained with reference to FIG. 2. Figure 2 A is a time chart of the DC voltage Vdc applied between terminals A and B, and B
is the time chart of the current Ir flowing through the resistor 10, C
is a time chart of the voltage Vgs applied between the gate and source of the field effect transistor 12, D is a time chart of the drain current Id of the field effect transistor 12, E is a time chart of the current I flowing through the light emitting diode 2, and F is a time chart of light emission. This is a time chart showing changes in the amount of light emitted E from the diode 2.

When the brake pedal is depressed, a switch (not shown) is turned on, and a voltage Vdc shown at A in FIG. 2 is applied between terminals A and B. Therefore, capacitor 11
and a current flows through the resistor 10. For this reason,
A current flows between the drain and source of the field effect transistor 12, and the light emitting diode 2 lights up.
During the first period 13 during which the field effect transistor 12 continues to be in the ON state, as shown in FIG.
flows, and the amount of light emitted from the light emitting diode 2 is large.
That is, since the first period 13 is set to a short time of 20 milliseconds, the light emitting diode 2 will not substantially generate heat even if a large current exceeding the maximum allowable current value is applied. Therefore, it is possible to light the light emitting diode 2 with a high amount of light emission commensurate with the current value.

Next, when the capacitor 11 is sufficiently charged and the current flowing through the resistor 10 decreases, the voltage applied to the resistor 10 becomes lower than the threshold value Vth of the field effect transistor 12, so the field effect transistor 12 is turned off. . Therefore, in the second period 14 when the field effect transistor 12 is turned off, the current I flowing through the light emitting diode 2 of the brake lamp 1 and the resistor 6 is lower than that in the first period 13 due to the current limitation by the resistor 7. It becomes smaller than the current I. Thereafter, when the brake operation is stopped, the switch is turned off, no voltage is applied between terminals A and B, and the light emitting diode 2 is turned off. After the field effect transistor 12 is turned off, terminals A and B
The second period 14 until the voltage disappears is longer than the first period 13, as shown in FIG.
Light emitting diode 2 has a maximum allowable current value of approx.
A current of 30mA flows.

As mentioned above, the difference between this embodiment and the conventional example is that the current value flowing through the brake lamp 1 is changed according to the present invention during the first period 13 at the initial stage of lighting and during the continuous second period 14 after the first period 13. The goal is to change it.
That is, a DC voltage Vdc is applied between terminals A and B of the lighting circuit 8.
A current 15 having a first current value is caused to flow during the initial first period 13 when the current value is added, and a current 16 having a second current value smaller than the first current value is caused to flow during the second period 14. As a result, this embodiment has the following effects.

That is, in this embodiment, as shown in FIG. 2E, a current 2.5 times the maximum allowable current value is continuously passed during the first period 13. Further, in a second period 14 that is sufficiently longer than the first period 13, a current of the maximum allowable current value is continuously passed through the light emitting diode 2. Therefore, in the first period 13, a large amount of light emission 1
7, the brake lamp 1 is illuminated, and the second period 14
Now, the brake light is 1 with the same amount of light as before, 18.
emits light. In this case, the light emitting diode 2 is not heated to a high temperature that would shorten its life and reduce its luminous efficiency.

FIG. 2F shows the amount of light emitted by the brake lamp 1 according to the lighting method of this embodiment. As shown in the figure, the amount of light emitted 17 during the first period 13 is the same as that of the conventional amount 1 of light emitted as shown by the dotted line.
The value is several times larger than 9. Also, the second
In period 14, a light emission amount 18 is obtained with a current at the same level as the conventional one, which is less than the maximum allowable current value.
Thereby, it is possible to turn on the brake lamp 1 with strong visual stimulation in the initial stage of lighting. In fact, as a result of comparing the case where the brake lamp was turned on with the lighting method of this example and the case where it was turned on with the conventional lighting method, the lighting method of this example was found to be more effective than the conventional method. It has been confirmed that the response to lamp lighting is quick. Further, even when the brake lamp was used for a long period of time using the lighting method of the present invention, no deterioration in reliability and characteristics was observed at all.

The present invention is not limited to the above embodiments, and various modifications are possible. For example, in the embodiment, the resistor 7 can be replaced with a diode or the like. In short, the lighting method according to the present invention is possible by varying the second resistance component connected in parallel to the first resistance component connected in series with the brake lamp 1. That is, in the first period at the initial stage of lighting, the second
This reduces the resistance component of the circuit, reduces the effective impedance of the circuit as seen from the power supply side, and allows a large first current to flow through the brake lamp. In the second period, the second resistance component is increased to increase the effective impedance of the circuit viewed from the power supply side, and a second current smaller than the first current is caused to flow through the brake lamp. Thereby, the lighting method of the present invention can be realized. Further, as shown in FIG. 3, a lighting circuit 8 has a parallel circuit of a capacitor 20 and a resistor 21 connected in series to the brake lamp 1.
It is also possible to use In this lighting circuit 8, a switch linked to the brake is turned on,
During the initial first period 13 when the power is turned on, a large current flows through the brake lamp 1 via the capacitor 20. Over time, capacitor 20
is charged, and the current flowing through the resistor 21 increases.
When the capacitor 20 is almost in a charged state, the second period 14 begins, and a nearly constant current flows into the brake lamp 1 through the resistor 21.

In addition, as shown in FIG.
The current flowing through the brake lamp 1 may be varied by varying the control current such as the base current flowing through the active element using an RC timer circuit consisting of the brake lamp 1.

Furthermore, the lighting method according to the present invention can be realized even if the voltage value from the power source is varied and applied to the brake lamp 1 by charging and discharging a capacitor, a constant voltage diode, or the like. In FIGS. 1 and 4, the first period 13 is set by the RC timer circuit, but it may be controlled by another external timer circuit.

Further, FIG. 5 is a time chart showing an example in which a pulse current I flows through the light emitting diode 2 during the first period 13, and a constant current flows during the second period. As shown in the figure, in the first period 13, the light emitting diode can be repeatedly turned on and off by intermittently passing current through the light emitting diode. By repeatedly blinking in this way, it is possible to further enhance visual stimulation. That is, by blinking the light emitting diode, the average current value in the first period 13 is reduced, and power consumption can be reduced. In other words, the light-emitting diode can be lit at a higher current value than when a constant current continues to flow. Moreover, after being lit for a specified period of time,
Even if the light-emitting diode turns off in about 20 milliseconds or less, due to the afterimage effect, it appears to human vision that the light emitting diode is continuously turned on with the amount of light emitted by the high current value. As described above, by blinking during the first period 13, it is possible to further increase the amount of light emitted from the light emitting diode without increasing power consumption, thereby increasing stimulation. Note that during the second period 14 as well, the amount of light emission may be increased by blinking in the same manner.

In the above embodiment, the first period 13 is 20 milliseconds, but it may be 2 to 150 milliseconds, preferably 5 to 100 milliseconds. Further, in the embodiment, the average current value in the first period was set to 2.5 times the average current value in the second period, but sufficient visual stimulation can be obtained if the average current value is 1.5 times or more. Further, the current value may be varied within the first period 13 and the second period 14. For example, a large current value may be used at the beginning of the first period 13 and the second period 14, and the current value may be gradually lowered. In this case, it is desirable that the maximum current value within the first period 13 be 1.3 times or more the maximum current value within the second period 14.

Effects of the Invention As described above, according to the lighting method and lighting device of the present invention, it is possible to turn on the same vehicle marker lamp as the conventional one with enhanced visual stimulation without reducing reliability. Furthermore, in order to obtain the same level of visual stimulation as in the past, the number of light emitting diodes used can be reduced, resulting in cost reduction and miniaturization.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram in which the lighting method for a vehicle marker lamp of the present invention is applied to a brake lamp exclusively for automobiles;
Figure A is a time chart of the DC voltage Vdc applied between terminals A and B, B is a time chart of the current Ir flowing through the resistor 10, and C is the time chart of the field effect transistor 12.
, D is the time chart of the drain current Id of the field effect transistor 12, E is the time chart of the current I flowing through the light emitting diode 2, and F is the amount of light emitted from the light emitting diode 2. FIG. 3 is a circuit diagram showing another embodiment of the present invention, FIG. 4 is a circuit diagram showing still another embodiment, and FIG. 5 is a time chart showing changes in E.
The figure is a time chart of the pulsed current flowing through the light emitting diode, Figure 6 is a perspective view of a conventional brake lamp, Figure 7 is a circuit diagram of a conventional lighting circuit, and Figure 8 is a diagram of a conventional brake lamp.
Figures A and B show time charts of voltage and current applied to a conventional lighting circuit, respectively. 1... Brake lamp, 2... Light emitting diode, 8... Lighting circuit, 9, 10... Resistor, 12...
...field effect transistor, 25...transistor.

Claims (1)

[Scope of Claims] 1. A process of lighting the light emitting diode at high brightness with a large current that exceeds the maximum allowable current value of the light emitting diode when a switch is turned on in conjunction with the operation of the brake pedal, and lighting the light emitting diode at high brightness. until the operation of the brake pedal is stopped and the switch is turned off after a certain period of time has elapsed.
A method for lighting a vehicle marker light, comprising: lighting the light emitting diode with a current that is less than or equal to the maximum allowable current value. 2. The process of lighting the light emitting diode at high brightness by intermittently flowing a large current exceeding the maximum allowable current value of the light emitting diode when a switch linked to the operation of the brake pedal is turned on; and the process of lighting the light emitting diode at high brightness. until the operation of the brake pedal is stopped and the switch is turned off after a certain period of time has elapsed.
A method for lighting a vehicle marker light, comprising: lighting the light emitting diode with a current that is less than or equal to the maximum allowable current value. 3. A switch that is linked to the operation of the brake pedal; a light emitting diode connected in series to the switch; a resistor connected in series to the light emitting diode; a switching element connected in parallel to the resistor; A vehicle characterized by comprising: a timer circuit connected to a control terminal of the switching element and maintaining the switching element on by supplying a control signal to the control terminal of the switching element for a certain period of time when the switch is turned on. Lighting device for marker lights.