CN101001491A - Failure and over-temperature protection method and device for light-emitting diode headlights for vehicles - Google Patents

Abstract

A failure and over-temperature protection method and device for a vehicle light-emitting diode head lamp are mainly characterized in that LED light sources of a far lamp and a near lamp are arranged in the LED head lamp, the current abnormity of each LED light source is detected in a matching manner, whether the LED light sources have failure problems or not is judged, the temperature in the LED head lamp is detected, whether over-temperature conditions exist or not is judged, when any LED light source is judged to be failed, the current lighting mode is immediately switched to another lighting mode to forcibly compensate the brightness of the failed LED light source, if the current lighting mode is judged to have the over-temperature condition, the brightness of the current lighting mode can be reduced firstly, then the over-temperature condition is detected to be continued or not, and if not, the current lighting mode is adjusted to the; if yes, immediately switching the current lighting mode to another lighting mode; therefore, the aim of cooling can be achieved by switching the illumination modes of the far lamp and the near lamp. The LED head lamp can achieve a good heat dissipation effect under the condition that the LED head lamp is started on the premise of avoiding the installation of a heat dissipation structure.

Description

Failure and over-temperature protection method and device for light-emitting diode headlights for vehicles

technical field

The invention relates to a failure and over-temperature protection method and device for a light-emitting diode headlight for a vehicle.

Background technique

The use of light-emitting diode (LED) components as light sources for vehicle headlights is a future trend. At present, all car lamp factories are researching and developing this future technology. The LED components have the advantages of low power consumption and easy control, but they are not used in headlights. Due to the limitations of the car body and regulations, a large number of LED components are needed due to insufficient brightness, but this causes the problem of overheating of the LED headlights and the inability to dissipate heat.

Although some car manufacturers have proposed solutions to this heat dissipation problem, most of them are structural heat dissipation designs. Adding a heat dissipation structure will increase the manufacturing cost and limit the size of the headlight.

Therefore, at present, no better heat dissipation technology has been proposed for LED headlights, and the development of LED headlights in the future is limited to a certain extent.

Contents of the invention

The main technical problem to be solved by the present invention is to overcome the defects existing in the prior art, and provide a vehicle LED headlight failure and over-temperature protection method and its device, under the premise of avoiding the installation of heat dissipation structure, the LED When the headlight is turned on, it can achieve a good heat dissipation effect.

The vehicle light-emitting diode headlight failure and over-temperature protection method of the present invention is:

A failure and over-temperature protection method for light-emitting diode headlights for vehicles, which is applied to an LED headlight including far light and near light lighting modes, and is characterized in that it includes the following steps: monitoring the current change of each LED light source, and judging whether If the current of any LED light source is abnormal, if it is, it means that the LED light source with abnormal current has failed, and the fail-safe procedure will be carried out; Near light or far light mode, if it is near light mode, switch to far light and reduce the brightness of far light; if it is far light mode, directly switch to near light, and make the near light reach full brightness; detection and Determine whether the temperature inside the lamp housing exceeds the preset over-temperature value, if yes, execute the over-temperature protection program, if not, return to the first step; to execute the over-temperature protection program, first lower the brightness of the current lighting mode, then detect and Judging that the current temperature in the lamp housing is lower than the predetermined over-temperature value, if so, then adjust back to full brightness, if not, then perform the next step; switch the current lighting mode to another lighting mode, that is, the current LED headlights are activated The modes include the near light mode or the far light mode. If it is the near light mode, switch to the far light mode and reduce the brightness of the far light; if it is the far light mode, it will directly switch to the near light mode. , and turn on the low lights at full brightness; return to the first step.

In the above-mentioned method for protecting LED headlights from failure and overheating, switching to the far light and reducing the brightness of the far light means reducing the brightness by about 4/5 of the original brightness of the far light.

In the above-mentioned vehicle LED headlight failure and over-temperature protection method, it is determined that the temperature inside the lamp housing is still higher than the over-temperature value, and a step of judging the frequent switching between the far light mode and the near light mode is added. If the switching is too frequent, then simultaneously Control the far lights and near lights to light up at the same time, and reduce the brightness of the far lights and near lights until the detected temperature is lower than the preset temperature, and then switch back to the near light lighting mode.

In the foregoing method for protecting LED headlights from failure and overheating, the brightness of the far light and the near light is lowered to about 2/5 of the original brightness.

The light-emitting diode headlight for vehicles with failure and over-temperature protection functions of the present invention is:

A light-emitting diode headlight for vehicles with failure and over-temperature protection functions, which is characterized in that it includes: a body consisting of a lamp housing, several LED light sources arranged in the lamp housing, and a cover arranged on the lamp housing A transparent lampshade with an opening in the lamp housing; a control circuit is located in the lamp housing of the body and is connected to the control terminals of each LED light source to detect the LED light source according to the temperature inside the LED headlight and the current supplied to each LED light source. The temperature of the headlight and whether the LED light source has failed, and then control the failure and over-temperature protection method in the LED headlight.

The aforementioned vehicle LED headlight with failure and over-temperature protection functions, wherein the control circuit includes: a microprocessor, which is built-in the failure and over-temperature protection method; a step-down module, which is connected to the microprocessor The output end of the device is controlled by the microprocessor to control the voltage of several LED light sources in the LED headlight to determine the brightness of each LED light source; a current detection unit is connected to the input end of the microprocessor and connected to the number in the LED headlight. A LED light source is connected to detect the current of each LED light source; a temperature detector is connected to the input end of the microprocessor to input the signal for detecting the temperature in the lamp housing into the microprocessor.

The beneficial effects of the present invention are:

From the description of the failure and over-temperature protection methods above, it can be seen that since the LED light source of the LED headlight is divided into the far light and the near light LED light source, in a normal operation, only one of the far light or the near light is lit, so this The invention utilizes this feature, when one of the lighting modes fails or overheats, it switches to another lighting mode, or lights up in conjunction with another lighting mode, to achieve auxiliary brightness and maintain the advantages of normal lighting required brightness, thus eliminating the need for The design of the heat dissipation device will not increase the production cost, and the volume of the LED headlight will not increase. On the premise of avoiding the installation of a heat dissipation structure, the LED headlight can achieve a good heat dissipation effect when it is started.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

FIG. 1 is a schematic structural view of the present invention applied to an LED headlight.

Fig. 2 is a circuit block diagram of the LED headlight control circuit of the present invention.

Fig. 3 is a flowchart of the protection method of the present invention.

Explanation of symbols in the figure:

LED headlight structure, which includes:

10 body 11 lamp housing

12 LED light source 13 Lampshade

20 control circuit 21 microprocessor

22 Buck module 23 Current detection unit

24 temperature detectors

Detailed ways

The present invention is aimed at the state of possible LED light source failure and over-temperature damage to the LED headlights for vehicles, and proposes a protection method. Therefore, the present invention is made in conjunction with an LED headlight with both far/near lighting modes. First, Referring to Fig. 1, it is an LED headlight structure capable of realizing the method of the present invention, which includes:

A body 10 is composed of a lamp housing 11, several LED light sources 12 arranged in the lamp housing, and a transparent lamp cover 13 covering the opening of the lamp housing 11;

A control circuit 20 is set in the lamp housing 11 of the main body 10 and is connected to the control terminals of each LED light source 12 to detect the LED headlight according to the temperature inside the LED headlight and the current supplied to each LED light source 12. Temperature and whether the LED light source 12 has failed, and then control the failure and over-temperature protection method in the LED headlight; please refer to FIG. 2, which is a circuit block diagram of the control circuit 20, which includes:

A microprocessor 21 is a built-in failure and over-temperature protection method of the present invention;

A step-down module 22 is connected to the output end of the microprocessor 21, and the microprocessor 21 controls the voltage of several LED light sources 12 in the LED headlight to determine the brightness of each LED light source 12;

A current detection unit 23 is connected with the input terminal of the microprocessor 21 and connected with several LED light sources 12 in the LED headlight to detect the current state of each LED light source 12; and

A temperature detector 24 is connected to the input end of the microprocessor 21 to input the signal for detecting the temperature inside the lamp housing 11 into the microprocessor 21 .

As can be seen from the above description, the microprocessor 21 can monitor the current status of each LED light source 12, and obtain the current temperature in the lamp housing 11, so as to perform failure and over-temperature protection methods. Please refer to FIG. 3 for the failure And a schematic flow chart of the over-temperature protection method, which includes:

Monitor the current change 50 of each LED light source, and judge whether there is an abnormal current 51 of any LED light source. If so, it means that the LED light source with abnormal current has failed, and the failure protection procedure is carried out; if not, skip the next step;

Executing the fail-safe procedure is to regard the lighting mode of the current headlight as near light or far light mode 52, if it is the near light mode, then switch to the far light, and reduce the brightness of the far light 54 (about 4/5 of the original brightness) , to avoid affecting the driving safety with the high brightness of the full bright far light; if it is the far light mode, directly switch to the near light 53, and make the near light reach full brightness;

Detect and judge whether the temperature inside the lamp housing exceeds the predetermined high temperature 65, 70, if yes, execute the over-temperature protection program, if not, return to the first step 50;

Executing the over-temperature protection program is to first lower the brightness of the current lighting mode 63, 71, and then detect and judge that the temperature inside the lamp housing is lower than the predetermined over-temperature value 67, 72, and if so, adjust back to the full brightness 68, 73 , if not, go to the next step;

Switch the current lighting mode to another lighting mode 69, 74, that is, the current start-up mode of the LED headlight includes a near light lighting mode or a far light lighting mode, if it is a near light lighting mode, switch to a far light lighting mode, And reduce the brightness of the far light to about 4/5 of the original brightness; if it is the far light lighting mode, directly switch to the near light lighting mode, and make the near light reach full brightness;

Return to the first step 50 .

As can be seen from the above description, the protection method of the present invention is to switch between the near light and the far light in the LED headlight. When the LED light source fails, the current lighting mode is switched to another lighting mode to temporarily compensate for the current lighting mode. When the LED light source is in an over-temperature state, first reduce the brightness of the current lighting mode to ease the current over-temperature state, and then check the temperature. If it still exceeds the over-temperature value, switch to another lighting mode directly. Turn off the current lighting mode to quickly alleviate the over-temperature state; if it is lower than the over-temperature value, then restore the full-brightness lighting of the current lighting mode.

However, when the headlights are turned on for a long time, the aforementioned protection methods may no longer be able to reduce the brightness or switch lighting modes to achieve the purpose of cooling down. Therefore, in the above-mentioned method flow program, when it is determined that the temperature is indeed overheated, then add a judgment Frequent switching between the far light mode and the near light mode 55, if the switching is too frequent, it means that the temperature of the far light and the near light remains high, so the far light and the near light are controlled to light up at the same time, but the brightness is reduced by 56, which is about 56% lower than the original The brightness is 2/5 brightness, and then detects whether the temperature is lower than the preset temperature 60, 61, if so, it will switch back to the low light lighting mode 62.

As can be seen from the above description, the present invention is based on the fact that the LED headlights are equipped with LED light sources for far lights and near lights. When the heat cannot be dissipated when the LED headlights are used at full brightness for a long time, one of them can be overheated by switching between them. The lamp can rest for a while, so that the temperature does not continue to rise, and then switch back to the original lighting mode after the temperature drops. Therefore, the present invention does not need to increase the heat dissipation structure at all, and can achieve overheating or failure by means of mutual driving. The problem of brightness enhancement.

Claims (6)

1. A vehicle light-emitting diode headlight failure and over-temperature protection method is applied to an LED headlight that includes a far light and a near light lighting mode, and is characterized in that it comprises the following steps: Monitor the current changes of each LED light source, and judge whether there is any abnormal current of any LED light source. If so, it means that the LED light source with abnormal current has failed, and the failure protection procedure is carried out; if not, skip the next step; To execute the fail-safe procedure, the lighting mode of the current headlights is regarded as the near light or the far light mode. If it is the near light mode, it will switch to the far light mode and reduce the brightness of the far light; if it is the far light mode, it will directly switch to the near light mode. lights, and turn on the near lights at full brightness; Detect and judge whether the temperature inside the lamp housing exceeds the predetermined over-temperature value, if so, execute the over-temperature protection program, if not, return to the first step; Executing the over-temperature protection program is to first lower the brightness of the current lighting mode, and then detect and judge that the temperature inside the lamp housing is lower than the predetermined over-temperature value. If yes, adjust back to full brightness. If not, then execute the next step ; Switch the current lighting mode to another lighting mode, that is, the current start-up mode of the LED headlights includes the near light mode or the far light mode. If it is the near light mode, switch to the far light mode and reduce the distance The brightness of the light; if it is the far light lighting mode, it will directly switch to the near light lighting mode, and make the near light reach full brightness; Return to the first step. 2. The vehicle LED headlight failure and over-temperature protection method according to claim 1, wherein said switching to the far light and reducing the brightness of the far light refers to reducing about 4/4 of the original brightness of the far light. 5 brightness. 3. The vehicle LED headlight failure and over-temperature protection method according to claim 1 or 2, characterized in that the temperature in the lamp housing is still higher than the over-temperature value, and a judgment is added to determine the far light mode and the near light mode. Frequent mode switching steps, if the switching is too frequent, control the far light and the near light to light up at the same time, and reduce the brightness of the far light and the near light until the detected temperature is lower than the preset temperature, and then switch back to the near light model. 4. The vehicle LED headlight failure and over-temperature protection method according to claim 3, characterized in that the brightness of the original brightness of the far headlight and the near light is lowered to about 2/5 at the same time. 5. A light-emitting diode headlight for vehicles with failure and over-temperature protection functions, characterized in that it comprises: A body is composed of a lamp housing, several LED light sources arranged in a row in the lamp housing, and a transparent lampshade covering the opening of the lamp housing; A control circuit is set in the lamp housing of the main body and is connected to the control terminals of each LED light source to detect the heat of the LED headlight and whether the LED light source is turned off according to the temperature inside the LED headlight and the current supplied to each LED light source. In the state of failure, then control the LED headlight to perform the described failure and over-temperature protection method. 6. The automotive LED headlight with failure and over-temperature protection functions according to claim 5, wherein the control circuit includes: A microprocessor with built-in failure and over-temperature protection methods; A step-down module is connected to the output terminal of the microprocessor, and the microprocessor controls the voltage of several LED light sources in the LED headlight to determine the brightness of each LED light source; A current detection unit is connected with the input terminal of the microprocessor and connected with several LED light sources in the LED headlight to detect the current of each LED light source; A temperature detector is connected to the input end of the microprocessor, so as to input the signal of detecting the temperature in the lamp housing into the microprocessor.

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