JPH09207660A - Rear lamp control circuit for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a rear lamp both as a brake lamp and a tail lamp in a simple structure and with small power consumption. SOLUTION: A switching device such as FET 14 or the like is disposed between a power supply such as a battery 10 or the like and a set of rear lamps 16A, 16B. A brake detecting signal of a brake switch S1 or the like and an on-off signal of a lamp switch S2 are input to a control device 18. The control device 18 changes the duty ratio of a control signal input to the switching device such as FET 14 or the like according to the operating condition of a brake and on-off state of the lamp switch S2, thereby changing the luminance of the rear lamps 16A, 16B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile rear lamp control circuit for controlling a rear lamp that is also used as a brake lamp and a tail lamp in an automobile.

[0002]

2. Description of the Related Art Generally, a rear part of an automobile is provided with a brake lamp which is turned on when the brake is operated and a tail lamp which is turned on at night. These lamps include
It is possible to use a single rear lamp as well, but in this case, in order to identify whether the brake is operating or whether it is lighting as a tail lamp, the rear lamp is turned on / off according to whether the brake is turned on or off. It is necessary to change the brightness of. Therefore, conventionally, for example, a circuit as shown in FIG. 2 is used as a means for controlling the brightness of the rear lamp.

In the figure, the rear lamp 40A on the left side is
The lamp 41A and the lamp 42A are housed in a common cell, and the lamp 40B on the right side is also formed.
Is configured by housing the lamp 41B and the lamp 42B in a common cell.

Of these, the left and right lamps 41A and 41B
Are connected in parallel to each other through a fuse 12 and a brake switch S1 to a plus terminal of a battery 10 which is a power source, and those having higher brightness than the lamps 42A and 42B are used. The brake switch S1 is turned on and off in conjunction with the operation of the brake, and is switched from off (open) to on (closed) when the brake is depressed.

The left and right lamps 42A and 42B are connected to the positive terminal of the battery 10 in parallel with each other through the fuse 12 and the switch in the relay 44, and the coil in the relay 44 is connected to the driving terminal. A lamp switch S2 that is turned on and off by a person is connected. When the lamp switch S2 is off (open), no current flows through the coil in the relay 44 and the switch of the relay 44 is turned off, while the lamp switch S2 is on (closed). A current flows in the coil from the battery 10 toward the lamp switch S2, and the switch of the relay 44 is turned on accordingly.

According to such a circuit, the brightness of each of the rear lamps 40A and 40B can be switched as follows by the driver's braking operation or the on / off operation of the lamp switch S2. When the brake is stepped on: Since the brake switch S1 is closed, the lamp 41A, day or night,
41B is energized, and the rear lamps 40A and 40B are turned on with high brightness. That is, it functions as a brake lamp. When the brake is not stepped on but the lamp switch S2 is turned on (that is, at night): The brake switch S1 is open, but the switch in the relay 44 is closed because the lamp switch S2 is closed. , The lamps 42A and 42B are energized. Therefore, the rear lamps 40A and 40B are turned on with lower brightness than when the brake is depressed. That is, it functions as a tail lamp. When the brake is not stepped on and the lamp switch S2 is off (that is, during the daytime): no lamp is energized and both rear lamps 40
A and 40B do not light.

Therefore, the person who sees the lighting state of both the rear lamps 40A and 40B can check the brightness of the rear lamps 4A and 4B based on the brightness.
It is possible to determine whether 0A and 40B are merely acting as tail lights or whether the brakes are operating.

[0008]

In the above circuit, each rear lamp 40A, 40B must be provided with two lamps in order to switch the brightness of the rear lamps 40A, 40B in two steps. For this reason, the wiring becomes complicated, and the structure of the rear lamps 40A and 40B itself becomes complicated and the size becomes large. Even if the rear lamps 40A and 40B are used as the brake lamp and the tail lamp, there is little merit. Further, the current consumption for energizing the coil of the relay 44 is relatively large.

In recent years, in order to simplify the structure of the rear lamp, two filaments having different luminances when energized are provided in a single lamp bulb, and when used as a tail lamp, the filament having lower luminance is used. There is also provided a device which is energized so that the filament on the high brightness side is energized when the brake is depressed. However, even in this case, the same circuit as the circuit shown in FIG. 2 must be used to control the energization of each filament. That is, even if a 1-bulb type rear lamp is used, it is necessary to individually control the energization of the two filaments contained therein,
Compared with the case of using two lamps, the contents of the energization control are substantially the same, which is not a basic improvement.

[0010]

As a means for solving the above-mentioned problems, the present invention is a rear lamp control circuit for an automobile for controlling a rear lamp that is also used as a brake lamp and a tail lamp in an automobile. When,
A switching device that is provided between the power source and the rear lamp and that is switched between an on state for connecting the power source and the rear lamp and an off state for disconnecting the power source and the rear lamp by a control signal input to a control terminal, A control signal input means for inputting a control signal to the switching device, a brake detection means for detecting whether or not the brake is operating, and a lamp for receiving a lamp lighting command in response to an external operation to the control signal input means. A switching means, and when a brake operation is detected, a control signal having a first duty ratio greater than 0 is input to the control terminal, the brake operation is not detected, and When the lamp lighting command is input from the lamp switching means, it is larger than 0 and the first duty ratio is larger than 0. If a control signal having a second duty ratio that is smaller than the above is input to the control terminal, the operation of the brake is not detected, and a lamp lighting command is not input from the lamp switching means, the control terminal is input to the control terminal. The control signal input means is configured so that a control signal for turning on the switching device is not input.

The term "duty ratio" as used herein means
It means the value of (time during which a control signal has a level for turning on a switching device in one pulse cycle) / (pulse cycle).

However, the present invention also includes the case where the first duty ratio is 100% (that is, the control signal is a signal which always maintains the switching device in the ON state and is not a pulse signal in a strict sense). Let's assume.

According to the above circuit, when the operation of the brake is detected, the control signal having the first duty ratio is input to the control terminal of the switching device, and as a result,
The rear lamp lights up with a relatively high brightness corresponding to the first duty ratio. Further, when the operation of the brake is not detected, but the lamp lighting signal is inputted from the lamp switching means to the control signal input means, the control signal having the second duty ratio smaller than the first duty ratio is obtained. Is input to the control terminal, and as a result, the rear lamp is lit with a relatively low brightness corresponding to the second duty ratio. On the other hand, the brake operation is not detected, and
When the lamp lighting signal is not input from the lamp switching means to the control signal input means, the control signal for turning on the switching device is not input to the control terminal,
Therefore, the rear lamp does not light.

That is, in this circuit, the duty ratio of the control signal input to the switching device is changed,
Since the brightness of the rear lamp is adjusted by so-called PWM control, the rear lamp can be used as a brake lamp and a tail lamp while the rear lamp is composed of a single lamp.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a preferred embodiment of the present invention will be described with reference to FIG.

The circuit shown is a battery 10 which is a power source.
A fuse 12, a p-channel FET (field effect transistor) 14 which is a switching device, a pair of left and right rear lamps 16A and 16B, a control circuit (control signal input means) 18, a brake switch S1 and a lamp switch S2. Provided with each rear lamp 16A, 16B
Consists of a single lamp with a single filament.

In the FET 14, the source-drain conducts only when the gate potential is lower than the source potential by a predetermined value or more (ON state), and otherwise the source-drain does not conduct. It will be in the state (off state). The source of the FET 14 is connected to the positive terminal of the battery 10 via the fuse 12, the drain is connected to one terminal of the rear lamp 16A and the one terminal of the rear lamp 16B, and the gate is connected to the control circuit 18. It is connected to the.

The other terminals of the rear lamps 16A and 16B are connected to the negative terminal of the battery 10,
These terminals are grounded.

The brake switch S1 and the lamp switch S2 are arranged in parallel between both terminals of the battery 10. The brake switch S1 is normally open, and is configured to be closed in conjunction with this when the brake of the vehicle is depressed. The lamp switch S2 is
It is provided near the driver's seat in the vehicle and is opened and closed by a driver or the like. The voltages that change depending on the ON / OFF state of the switches S1 and S2 are input to the control device 18 as a detection signal and a lamp lighting command signal, respectively.

The control device 18 is composed of a microcomputer, a transistor and the like, and outputs a signal having a duty ratio according to the ON / OFF of the switches S1 and S2 to the FET1.
It is configured to be inputted as a control signal to the gate of No. 4. Specifically, the duty ratio of the output signal of the control device 18 is set as follows.

[0021]

[Table 1]

According to this circuit, the following effects can be obtained.

When the brake is depressed: The brake switch S1 is turned on, and a signal corresponding to this is input to the control device 18. Control device 1 which received this
Numeral 8 inputs a signal having a duty ratio of 100% (first duty ratio) (that is, a signal for keeping the FET 14 always in the ON state) to the gate of the FET 14 as a gate signal regardless of whether the lamp switch S2 is on or off.
The source-drain of No. 4 is always electrically connected. Therefore, in this case, regardless of whether the lamp switch S2 is on or off (that is, regardless of day or night), the rear lamps 16A and 16A are
B lights up with high brightness.

If the brake is not depressed but the lamp switch S2 is turned on: the control unit 1
8 inputs a pulse signal having a duty ratio of X% (second duty ratio) to the gate of the FET 14 as a gate signal. As a result, the source and drain of the FET 14 are intermittently conducted only during the period corresponding to the duty ratio of X%. Therefore, in this case, both the rear lamps 16A and 16B light up with a lower brightness than when the brake pedal is depressed, and these rear lamps 16A and 16B function as tail lamps.

When the brake is not depressed and the lamp switch S2 is off: The control device 18 controls the FET 14
Signal with a duty ratio of 0% (that is, always F
A signal for keeping the ET 14 in the off state) is output. Therefore, the source and drain of the FET 14 do not conduct, and the rear lamps 16A and 16B do not light at all.

As described above, in this circuit, the FET 14 is provided between the battery 10 and both rear lamps 16A and 16B.
And the rear lamps 16 are controlled by the so-called PWM control in which the duty ratio of the signal input to the gate is changed.
Since the brightness of A and 16B is adjusted, these rear lamps 16A and 16B can be used both as a brake lamp and a tail lamp while configuring each rear lamp 16A and 16B with a single lamp, and compared with the conventional circuit. Thus, the structure and wiring of the rear lamps 16A and 16B themselves can be simplified. Further, the power consumed for inputting the gate signal to the FET 14 is small, and the power consumption of the entire circuit is small as compared with the conventional one using a relay.

The "switching device" in the present invention is not limited to the FET 14 described above, and various other transistors suitable for PWM control can be applied. In either case, good rear lamp control is possible by operating the duty ratio of the control signal input to the control terminal (base in the case of a bipolar transistor) of the switching device.

The "first duty ratio" in the present invention does not have to be 100% as described above, but is 0%.
It may be freely set in a larger range according to the specifications. Similarly, the "second duty ratio" can be appropriately set within a range larger than 0% and smaller than the first duty ratio.

[0029]

As described above, according to the present invention, the switching device is arranged between the power source and the rear lamp, and the duty ratio of the control signal input to the control terminal of the switching device is determined by the operation of the brake and the lamp switching means. Since it is designed to change according to the presence or absence of a lamp command signal, each rear lamp is composed of a single lamp, and while simplifying the structure and wiring of these rear lamps, each rear lamp can be used as a brake lamp with low power consumption. It has the effect that it can be used well as a tail lamp.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a preferred embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional rear lamp control circuit.

[Explanation of symbols]

 10 Battery (Power Supply) 14 FET (Switching Device) 16A, 16B Rear Lamp 18 Control Circuit (Control Signal Input Means) S1 Brake Switch (Brake Detection Means) S2 Lamp Switch (Lamp Switching Means)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Hoshino 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi Harness Research Institute Co., Ltd.

Claims (1)

[Claims] 1. A rear lamp control circuit for an automobile for controlling a rear lamp that is also used as a brake lamp and a tail lamp in an automobile, comprising: a power supply; and a control terminal provided between the power supply and the rear lamp. A switching device that is switched between an on state for connecting the power source and the rear lamp and an off state for disconnecting the power source and the rear lamp by a control signal, and a control signal input means for inputting a control signal to the switching device,
The brake detection means for detecting whether or not the brake is operating, and the lamp switching means for receiving a lamp lighting command in response to an external operation to the control signal input means are provided, and the operation of the brake is detected. 0 if
A control signal having a larger first duty ratio than the above is input to the control terminal, and the operation of the brake is not detected,
When a lamp lighting command is input from the lamp switching means, a control signal having a second duty ratio larger than 0 and smaller than the first duty ratio is input to the control terminal, When the operation of the brake is not detected and the lamp lighting command is not input from the lamp switching unit, the control signal input unit is set not to input the control signal for turning on the switching device to the control terminal. A rear lamp control circuit for an automobile, which is configured.