JPH04317833A - Vehicle indicator lamp control circuit - Google Patents

Abstract

PURPOSE:To conduct surely illumination control reducing the illumination of an indicator lamp at nighttime and prevent control action from being affected even with temperature change, static electricity and outside noise or the like. CONSTITUTION:At an indicator lamp lighting circuit 24, an indicator lamp 10 such as LED and the 1st resistor R5 are connected in series, and the lamp 10 is lighted by means of a lamp power source 14, and at a nighttime illumination circuit 22, a lamp power source 14 and a nighttime illumination lamp 18 are connected to each other with a nighttime illumination switch 16 interposed. And, a B point between the switch 16 and the lamp 18 and an A point between the lamp 10 and the resistor R5 are connected to each other through the 2nd resistor R6. As result, when the switch 16 is closed at nighttime, potential at the A point rises more than in daytime, and indicator 10 both end voltage is descended, so the illumination of the indicator lamp 10 can be lowered surely.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle indicator lamp control circuit that changes the illuminance of an indicator lamp on an instrument panel between daytime and nighttime.

0002

[Prior Art] Conventional vehicle instrument panels are equipped with indicator lamps that visually display the operating status of an air conditioner (A/C) in an easy-to-understand manner by emitting light from a light emitting diode (LED) or a bulb. It is set up.

However, the above indicator lamp has a visibility problem in that if the illuminance is adjusted during the daytime when the surroundings are bright, it will be dazzling at night, and conversely, if it is adjusted at night, it will be difficult to see during the daytime.

FIG. 8 shows a control circuit diagram of a conventional vehicle indicator lamp. The circuit shown in FIG. 8 lights up the indicator lamp 10 to display the operating status of the air conditioner on the instrument panel.

First, when the operation switch 12 of the air conditioner is turned on, current from the lamp power source 14 flows, lighting the indicator lamp 10 for visual display, and operating the air conditioner (not shown).

Therefore, during daytime driving, the night light switch 16 shown in FIG. 8 is open and the night light lamp 18 is turned off. Since the base side of the transistor (TR1) is grounded via the resistor (R3) and the rheostat 20, the transistor (TR1) is turned on. As a result, the current from the lamp power supply 14 passes through the transistor (TR1), the diode (D1), the resistor (R2), and the diode (D2) to the LED indicator lamp 1.
0 lights up.

When driving at night, the outside of the vehicle is illuminated by closing the night light switch 16 and lighting the night light lamp 18. At this time, transistor (TR1)
Since there is no potential difference between base and emitter, OF
F works. As a result, the current from the lamp power supply 14 flows through the resistor (R1) without passing through the transistor (TR1).
, LE through the resistor (R2) and diode (D2)
Turn on the indicator lamp 10 of D.

[0008] As described above, the current path of the indicator lamp 10 differs between daytime and nighttime due to the switching operation of the transistor (TR1), and at nighttime, the current path passes through an extra resistor (R1), resulting in a voltage drop. The illuminance of the indicator lamp 10 is reduced to prevent the indicator lamp from dazzling when driving at night.

[0009]

As described above, in the conventional vehicle indicator lamp control circuit, the transistor (TR1) is activated by opening and closing the night light switch 16 shown in FIG.
The illuminance was adjusted by changing the base voltage of the indicator lamp 10 and passing it through an extra resistor (R1) during nighttime through a switching operation to lower the voltage applied to the indicator lamp 10.

However, in the conventional control circuit described above, since various resistances are mounted on the vehicle wiring harness on the base side of the transistor (TR1), even when the switch 16 is closed at night, the transistor (TR1) )
The base voltage (Vb) of the transistor (TR1) becomes lower than the emitter voltage (Ve), and the transistor (TR1) may turn on when it should normally turn off. In this way, at night, unless the transistor (TR1) is turned off reliably, the current will not pass through the resistor (R1), so the illuminance of the indicator lamp 10 will be the same as during the day, making the driver feel dazzled. There was a problem.

[0011] Furthermore, since transistors, which are active elements, have conventionally been used in indicator lamp control circuits,
There have been problems in that operation becomes unstable due to temperature changes, and malfunctions and damage are likely to occur due to static electricity and external noise.

Furthermore, since switching is conventionally performed using transistors, there is a problem in that the number of parts is large and the parts configuration becomes complicated.

The present invention has been made to solve the above-mentioned problems, and it is possible to reliably control the illuminance of the indicator lamp by changing it between daytime and nighttime, and also to prevent temperature changes and static electricity. Another object of the present invention is to provide a vehicle indicator lamp control circuit whose control operation is not affected by external noise, etc., and which can be easily configured with a small number of parts.

[0014]

[Means for Solving the Problems] In order to solve the above problems, in a vehicle indicator lamp control circuit that causes an indicator lamp on an instrument panel to emit light to visually display the operating status of each part of the vehicle, a first resistors are connected in series, and includes an indicator lamp lighting circuit that lights an indicator lamp using a lamp power source, and a night lighting circuit that blinks a night lighting lamp by opening and closing a night lighting switch, and the night lighting circuit includes the A second resistor is provided between the indicator lamp and the first resistor of the indicator lamp lighting circuit, and the second resistor has one end connected to the night light switch and the other end connected to the night light switch, and when the night light switch is closed, the night light power supply is connected. is supplied to the first and second resistors to reduce the voltage across the indicator lamp, thereby reducing the illuminance of the indicator lamp.

[0015]

[Operation] In the vehicle indicator lamp control circuit according to the present invention, the second resistor of the night light circuit is connected between the indicator lamp and the first resistor of the indicator lamp lighting circuit, and the second resistor of the night light switch is connected between the indicator lamp and the first resistor of the indicator lamp lighting circuit. By changing the voltage across the indicator lamp by opening and closing,
With a simple configuration, it is now possible to control the illuminance of the indicator lamp so that it is dimmed more reliably at night than during the day and does not dazzle.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle indicator lamp control circuit according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a circuit diagram showing a vehicle indicator lamp control circuit according to Embodiment 1 of the present invention. As shown in FIG. 1, the indicator lamp control circuit of the first embodiment includes an indicator lamp lighting circuit 24 and a night illumination circuit 22.

The indicator lamp lighting circuit 24 includes:
An indicator lamp 10 consisting of a light emitting element such as an LED or a bulb, an auxiliary resistor (R4), and a first resistor (R
5) are connected in series, and the indicator lamp 10 is lit by a voltage supplied from a lamp power source 14 of, for example, a 12V vehicle battery.

The night lighting circuit 22 is connected to the power supply 1 here.
4 and a night illumination lamp 18 are connected across a night illumination switch 16, and the night illumination lamp 18 can be made to flicker by opening and closing the night illumination switch 16.

Point B between the night light switch 16 and the night light lamp 18 of the night light circuit 22, and the point B between the indicator lamp 10 and the first resistor (R5) of the indicator lamp lighting circuit 24. is connected to point A through the second resistor (R6).

The first embodiment is constructed as described above, and its operation will now be explained based on FIG. 2.

FIG. 2 is an explanatory diagram of the operation of the vehicle indicator lamp control circuit of FIG. 1. As shown in Figure 2,
When the vehicle is running during the day, the night light switch 16 is open. Therefore, the current I1 from the lamp power supply 14 is
The indicator lamp 10 is turned on and the current is divided into the currents I2 and I3 at the branch point A. At this time, a voltage of 12V from the lamp power supply 14 is applied to the indicator lamp 10, and the potential on the negative side of the indicator lamp 10 is 9V.
It will be about. Therefore, a voltage of 3V is applied to both ends of the indicator lamp 10, and a current of about 20mA flows. Furthermore, the potential at point A drops to about 3V because it passes through the auxiliary resistor (R4).

Next, when driving at night when the instrument panel is dark and difficult to see, the driver closes the night light switch 16 shown in FIG. 2 to turn on the night light lamp 18. At this time, since the potential at point B increases, a current I4 flows in the second resistor (R6) in the opposite direction to that during the daytime. Therefore, the potential at point A increases from 3V during the daytime to about 5V. As a result, the voltage across the indicator lamp 10 drops from 3V to about 1.5V, and the current also becomes about 5mA, so the indicator lamp 10
It is possible to reliably reduce the illuminance of 0.

As described above, the indicator lamp control circuit of the first embodiment has a simple configuration and controls the night light switch 16.
Since the voltage across the indicator lamp 10 can be controlled in response to the opening/closing operation of the indicator lamp 10, the illuminance of the indicator lamp can be reliably lowered at night to suppress glare.

Embodiment 2 FIG. 3 is a circuit diagram showing a vehicle indicator lamp control circuit according to Embodiment 2 of the present invention. As shown in FIG. 3, the indicator lamp control circuit of Embodiment 2 has approximately the same circuit configuration as that of Embodiment 1, but its characteristics are that The second resistor (R6) is arranged as a series line of the second resistor (R7) and the diode (D5).

As described above, in the second embodiment, since the diode (D5) is provided, the current I2 that is shunted from point A as shown in FIG. 2 does not flow during the daytime.
Excess power consumption can be eliminated. Then, at night, as in the first embodiment, the potential at point A is raised and the voltage across the indicator lamp 10 is lowered, so that the illuminance of the indicator lamp 10 can be reliably lowered.

In the first and second embodiments (FIGS. 1 to 3), an auxiliary resistor (R4) is arranged between the indicator lamp 10 and point A, but it may be omitted. The same effect as above can be obtained.

FIG. 4 is a circuit diagram of a vehicle indicator lamp control circuit that controls a plurality of indicator lamps. As shown in FIG. 4, for example, an instrument panel of a vehicle is provided with an air conditioner switch 12-1, an audio device switch 12-2, and other mode switches 12-3. Each of the indicator lamps 10-1 to 10-6 lights up when the switch group 12 is turned on or off, providing a visual indication to the driver. and,
At the same time, the operation of each device is controlled. In Figure 4,
Each indicator lamp 10-1 for lamp power supply 14
10-6 are connected in parallel, and are connected to each switch group 12, respectively.

On the other hand, the night illumination lamp 18 flickers as the night illumination switch 16 is opened and closed. When the night light switch 16 is closed, the current from the lamp power source 14 passes through the second resistor (R8), (R9) or (R10) and the diode (D6) from point B, respectively. The potential at each point A between the negative side of the indicator lamp 10 and the first resistors (R12), (R14), and (R16) is increased. Therefore, the voltage across the lit indicator lamp is reduced, and the illuminance can be reduced to a value suitable for night driving.

Embodiment 3 Each figure in FIG. 5 is an explanatory diagram of the operation of a vehicle indicator lamp control circuit according to Embodiment 3 of the present invention, in which (a) is a diagram showing the open state of the night light switch; (b) is a state diagram of the night light switch when it is closed. As shown in FIG. 5(a), the third embodiment is similar in configuration to the first embodiment shown in FIG. It is not connected. A night light circuit that blinks a night light lamp (not shown) is configured as a separate circuit, and the night light switch 16 shown in FIG. 5 is opened and closed in conjunction with the switch of the night light circuit. In the third embodiment, the night light switch 16 and the second resistor (R6) are connected in parallel with the indicator lamp 10.

Therefore, as shown in FIG. 5(a),
When the night light switch 16 is opened, a current I5 flows from the lamp power source 14 through the series circuit of the indicator lamp 10, the auxiliary resistor (R4), and the first resistor (R5), causing the indicator lamp 10 to light up. Next, Figure 5(b)
As shown in FIG. 5, when the night light switch 16 is closed, the current I6 flows together with the current I7, raising the potential at the merging point A more than in FIG. 5(a). Therefore, I5 > I7, and when the night light switch 16 is closed, the illuminance of the indicator lamp 10 can be reliably reduced.

Embodiment 4 FIG. 6 is a circuit diagram showing a vehicle indicator lamp control circuit according to Embodiment 4 of the present invention. As shown in FIG. 6, the fourth embodiment is composed of an indicator lamp lighting circuit 24 and a night lighting circuit 22 like the first embodiment. One end of the second resistor (R19) is connected at point C between the first resistor (R17) of the indicator lamp lighting circuit 24 and the positive side of the indicator lamp 10, and the other end is connected to the night light switch 16 and the positive side of the indicator lamp 10. It is grounded via the night illumination lamp 18.

Next, the operation of the fourth embodiment will be explained.

As shown in FIG. 6, the night light switch 16 is open during the daytime. Therefore, the lamp power supply 14
The current from the first resistor (
R17) and the auxiliary resistor (R18) to light up the indicator lamp 10.

Next, at night, the night light switch 16
When closed, current flows from point C to both the indicator lamp lighting circuit 24 and the night lighting circuit 22.
The potential at point C is lowered, and the voltage across the indicator lamp 10 can be lowered. In the fourth embodiment, with such a simple configuration, the illuminance of the indicator lamp 10 at night can be reliably reduced.

Embodiment 5 FIG. 7 is a circuit diagram showing a vehicle indicator lamp control circuit according to Embodiment 5 of the present invention. As shown in FIG. 7, the fifth embodiment has a night lighting circuit 2 similar to the fourth embodiment.
One end of the indicator lamp 2 is connected at a point C between the first resistor (R17) of the indicator lamp lighting circuit 24 and the positive side of the indicator lamp 10, and the other end is grounded. The difference from Example 4 is that the second resistor (R18) has zero resistance value.

Also in this case, during the daytime when the night light switch 16 is open, the current from the lamp power supply 14 passes through the first resistor (R17) and lights the indicator lamp 10.

Furthermore, at night when the night light switch 16 is closed, current flows from point C to both the indicator lamp lighting circuit 24 and the night light circuit 22, so the potential at point C decreases and the voltage across the indicator lamp 10 also decreases. descend.

Therefore, in the fifth embodiment, the illuminance of the indicator lamp 10 can be reliably reduced at night with a simple configuration.

As described above, the vehicle indicator lamp control circuit of the above embodiment connects the night lighting circuit between the indicator lamp and the resistor of the indicator lamp lighting circuit, and by closing the night lighting switch,
The illuminance can be reliably reduced by lowering the voltage across the indicator lamp.

[0041]

As explained above, according to the vehicle indicator lamp control circuit of the present invention, the voltage across the indicator lamp is changed by the opening/closing operation of the night light switch, and the illuminance of the indicator lamp is increased compared to daytime. It is configured to dim the light at night. Therefore, the indicator lamp control circuit of the present invention can be easily configured with a small number of parts, ensures reliable and stable dimming of the indicator lamp at night, and ensures that the visual display on the instrument panel is always appropriate. It can be done in the same condition.

Furthermore, since the present invention does not use a transistor to dim the indicator lamp, it is not affected by temperature changes or voltage drops due to harness resistance, and is free from malfunctions or damage due to static electricity or external noise. I no longer have to worry about this happening.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a vehicle indicator lamp control circuit according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the vehicle indicator lamp control circuit of FIG. 1;

FIG. 3 is a circuit diagram showing a vehicle indicator lamp control circuit according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a vehicle indicator lamp control circuit that controls a plurality of indicator lamps.

FIG. 5 is an explanatory diagram of the operation of the vehicle indicator lamp control circuit according to the third embodiment of the present invention. (a) is a state diagram of the night light switch when it is open. (b) is a state diagram of the night light switch when it is closed.

FIG. 6 is a circuit diagram showing a vehicle indicator lamp control circuit according to a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a vehicle indicator lamp control circuit according to a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram of a conventional vehicle indicator lamp control circuit.

[Explanation of symbols]

10 Indicator lamp 14 Lamp power supply 16 Night light switch 18 Night light lamp 22 Night light circuit 24 Indicator lamp lighting circuit R5, R12, R14, R16, R17 First resistor R6, R7, R8, R9, R10, R19 Second Resistor R14 Resistor R16 Resistor R17 Resistor

Claims (1)

[Claims] 1. A vehicle indicator lamp control circuit that visually displays the operating status of various parts of the vehicle by emitting indicator lamps on an instrument panel, wherein a first resistor is connected in series to the indicator lamp, and the lamp is powered by a lamp power source. an indicator lamp lighting circuit that lights up an indicator lamp; and a night lighting circuit that makes the night lighting lamp blink by opening and closing a night lighting switch, and the night lighting circuit includes an indicator lamp of the indicator lamp lighting circuit and a first resistor. a second end connected to the body and the other end connected to the night light switch;
A resistor is provided, and when the night light switch is closed, night light power is supplied to the first and second resistors to reduce the voltage across the indicator lamp, thereby reducing the illuminance of the indicator lamp. It is characterized by