Vehicle lights

The invention relates to a rear light for motor vehicles according to the preamble of claim 1.

So far, LED lights only as high mount stop lamps in Motor vehicles used. The adaptation of the LEDs to the vehicle voltage is realized via series resistors. This can under certain operating conditions to a current overload and a temperature overload LEDs come. The sequence of Overload, a lessening of light output to failure his or changing the light color.

The invention is based on the object, the generic Rear light in such a way, that they in any operating condition Motor vehicle reliably.

This object is in the generic taillight having the characterizing features of claim 1 dissolved.

In the rear light according to the invention is at least one of their Lights, preferably all lights, formed by LEDs. The operating current of the LEDs is over a voltage range at least kept approximately constant. Characterized there is no current overload and / or temperature overloading the LEDs. Their light output therefore remains on the service life of at least approximately constant. A change occurs its light color is not one.

Further features of the invention result from the additional claims, the description and the drawings.

The invention will be with reference to an illustrated in the drawings explained embodiment example. Show it<dl tsize="20"><dt>Fig. 1</dt><dd>a block diagram of an inventive control device for LEDs,</dd><dt>FIG. 2a to FIG. 2f</dt><dd>arranged various circuit examples in groups LEDs,</dd><dt>Fig. 3</dt><dd>the circuit diagram of a low voltage level to the invention Control device of FIG. 1,</dd><dt>Fig. 4</dt><dd>the diagram of a total failure detection of the present invention Control device of FIG. 1,</dd><dt>Fig. 5</dt><dd>the circuit diagram of a constant current regulator of the present invention Control device of FIG. 1,</dd><dt>Fig. 6</dt><dd>the circuit diagram of a surge protector of the present invention Control device according to FIG. 1,</dd><dt>Fig. 7</dt><dd>the circuit diagram of an LED failure detection of the present invention Control device of FIG. 1.</dd></dl>

The controller is designed to operate a rear light of a Motor vehicle provided having LEDs as light source. With the controller is a constant brightness of the LEDs, preferably over the entire voltage waveform, is reached.

The control device has an interface 1 (Fig. 1), via which the Control electronics from the electrical system of the motor vehicle is a functional signal receives. It activates the control device by which it is the associated LEDs are controlled. Downstream of the interface 1 is a supply voltage controller 2 with which the control device their supply voltage from the via the interface 1 generated control signal supplied. The power supply regulator 2 is designed so that the quiescent current consumption less than 1 mA is. The power supply regulator 2 are interposition a diode 42 constant current regulator 3 to 5 downstream. Of the Constant current regulator 3 is the brake light 6, the constant current regulator 4 the flashing light 7 and the constant current controller 5 the taillight 8 assigned to the taillight. The constant current regulator 3 to 5 are identical design and measure the current at a measuring resistor 9 (FIG. 5). The resistance measured by means of a Comparator 10 is compared with a reference voltage eleventh The output of the comparator 10 is an actuator 12 is supplied, which is preferably a power MOSFET. About this actuator 12 is an LED array 13 with the interposition of a protective diode 14 regulated. The controller monitors the vehicle electrical system voltage. If a predetermined voltage value,_Max exceeded so the constant current controller switches 3 to 5 in a definable secure state in order to prevent overloading of the actuator 12th The constant current regulator has 3 to 5 for the overvoltage protection a corresponding terminal 15. The constant current regulator 3 to 5 is advantageous for a working range of 9 volts to 16 volts designed.

The constant current controllers 3-5 is a common overvoltage protection assigned 16 to avoid overloading the actuator 12 the respective constant current regulator 3 to prevent up. 5 As shown in FIG. 6 shows the surge protector 16 has an actuator 17 in the form of a Transistor. preceded him, a resistor 18 and a Protection diode 19. The resistor 18, the voltage command is carried out. The surge protector 16 is, like FIG. 1, at the interface 1 connected to the control device. Once the predetermined Voltage value,_Max is exceeded, via the actuator 17 of the surge protector 16 of the respective constant-current regulator 3-5 is switched so that an overload of the actuator 12 of the respective constant current regulator 3 is excluded up. 5

About the supply voltage regulator 2 is at the interface 1 a LED failure detection connected 20th It is the flashing light 7 associated with and monitors the failure of a LED blinking indicator 7, which is formed by a LED matrix. Fig. Figure 7 shows the LED array 21, which forms the indicator. 7 The LED matrix 21 is as Four matrix formed having four rows of four LEDs. On the LED array 21 takes a Istwertabgriff, that is the Voltage across the upper and the lower matrix half by means of a Comparator 22 compared. He receives the measured to the LED array 21 Actual voltage value and compares it with a a Voltage divider 23 supplied target voltage value. Are all LEDs of the LED array 21 in order, is only one component-related small Deviation between the voltages of the upper and determine lower matrix half. Smaller in a matrix half a LED off, the voltage drop increases in this matrix half. Of the Comparator 22 then outputs a corresponding output signal which can be evaluated. This output signal of the comparator 24 22 of the interface 1 is supplied, via the example trigger an optical and / or acoustic signal in the motor vehicle can be that advises the driver that at least one LED has failed in the flashing light. 7

Since the failure detection 20 of the voltage drop across both Halves of the LED array is measured, for the flashing light 7 only a twin, four-, six-, etc. matrix are provided. Of the exactly simultaneous failure of one LED in each matrix half is extremely unlikely.

The failure detection described 20 may also for the brake light 6 or the tail light are used 8.

To a total absence of operation of the tail light of the vehicle for example, a broken cable or a connector damage capture, a total failure detection 25 is provided (Fig. 1 and 4), to which via the constant current regulator 3 to 5, the Brake light, the flashing light 7 and the tail light 8 connected are. The output 26 of the total failure detection is 25 the interface 1 is supplied. The interface 1, an optical and / or acoustic signal in the vehicle are triggered, to make the driver's attention that the rear light the motor vehicle has failed completely.

The total failure detection 25 has a comparator 27 (Fig. 4), the a reference voltage 28 with an actual voltage value compares, the means of the measuring resistor 9 of the respective constant current regulator 3 to 5 is measured. Turns out the tail light, generates the Comparator 27, the output signal 26, the interface 1 is supplied becomes.

The tail light 8 is a low voltage level 29 assigned to the ensures that the tail light 8 below a limit voltage switched example of a four-matrix to a two-matrix becomes. As shown in FIG. 3, the tail light 8 is controlled by a LED array 30 formed of and a relay 31 having a coil 32 Switch contacts 33 and a diode 43 are connected in series. The relay 31 is an actuator 34, preferably a transistor controlled. Upstream of the relay 31 is a comparator 35, of a Target voltage value 36 with a measured 37 Istspannungswert compares. For voltage detection is a voltage divider consisting of two series-connected resistors 38, 39 is provided. The setpoint is formed by a resistor 40 and a Zener diode 41st

The current regulation is for a working range of preferably about 9 volts to about 16 volts designed. To the tail light 8 to To operate a voltage of, for example, 6 volts, the example provided four matrix 30 to a two-matrix switched. The electronic control unit itself operates down to a Voltage of the embodiment 5.1 volts. This switching function can, if desired, also for the brake light 6 the flashing light may be used 7 and / or. To the four-Matrix 30 switch the tail light 8 on the two-Matrix, is the Relay 31 is switched over the actuator 34th

The tail light 8 has two power levels. The taillight can be a have taillight function and a brake function. For normal Taillight function is sufficient, a lower current. For the brake function a high current is required since the LEDs for the taillight 8 driven along with the LEDs of a stoplight. 7 The current value can change the default voltage divider the respective constant current regulator 3 can be freely set up. 5 The level switch is by parallel connection of an additional Resistance reaches at the voltage divider.

The setting at least two current levels and their control by various signals is also the stop lamp 6, and / or the flashing light 7 possible.

The brake light 6, the flashing light 7 and the tail light 8 forming LEDs are advantageously arranged in a matrix form. This has the Advantage that the failure of a LED the other LEDs continue to shine. To be placed on this security no value, the LEDs also show, as Figs. 2a to 2c may be connected in series. Fig. 2a shows the possibility of the LEDs in rows of five parallel to each other to switch. FIG. 2b shows four series-connected LEDs, while apparent from Fig. 2c that the LEDs in a series of two can be arranged.

Figs. 2d to 2f show examples of matrix circuits of the LEDs. According to Fig. 2d, the LEDs are in a five-matrix according to Fig. 2e 2f arranged in a four-matrix and according to FIG. In a two-matrix. In the illustrated embodiment, for the brake light 6, 7, the flashing light and the tail light 8 advantageously a four-matrix chosen to operate at a forward voltage of about 2.5 volts per LED minimize power loss at the actuator 14 of the respective constant current regulator 3 to get up. 5 For other operating voltages or LEDs with different forward voltages are also twins, Triple, five or other arrays of LEDs possible.

With the described control device of the current for the LEDs is the different lights of the tail light of the vehicle on a certain voltage range by a control constant kept. The current detection in the current regulators 3 through 5 is made via the transmitter 9 in the form of a measuring resistor. The current regulation can more freely adjustable current level have, as an example of the tail light 8 with reference to FIG. has been explained 3rd The adjustment of the different current levels via a variable divider ratio of the various Resistors 38 to 40 of the low voltage level 29. The current regulator 3 to 5 are protected against overvoltage. In one occurrence Voltage which has a predetermined maximum voltage value U_Max exceeds the current regulator 3 to 5 are in a defined state brought, in which the LEDs of a stoplight 6, a blinking indicator 7 and the tail light 8 and for the current regulator 3 to 5 there is no danger. The tail light 8 can be up to a voltage of U_min be operated as from a threshold the example used for the taillight 8 quad-matrix 30 in a two-matrix is switched. For example, the operation of the Tail light 8 as a four-LED matrix until a voltage of for example, 3.5 volts above U_min possible. The current for the Brake light 6, the flashing light 7 and the tail light 8 is the Total failure detection monitors and displays 25th With the LED failure detection 20 is the voltage across the two halves of the LED matrix 21 monitors to detect the failure of individual LEDs. If one LED in the LED array 21, this becomes by a RISING of the voltage drop at the corresponding matrix half noticeable. Since the operating current for the LEDs within a certain voltage range is kept constant, a obtain optimum light output of the LEDs. Also, the chip temperature the LEDs can be kept very low, so that the LEDs a have long life.