JP6924559B2 - Light emitting diode device - Google Patents

Description

The present invention relates to a light emitting diode device, and more particularly to a light emitting diode device including a large number of light emitting diodes arranged in a planar light emitting region.

In recent years, in vehicle headlights, a technique (called an ADB adaptive driving beam) that controls the light distribution shape in real time according to the situation in front, that is, the presence or absence of an oncoming vehicle, a vehicle in front, and the position thereof, has attracted attention. ..

According to this ADB technology, for example, when an oncoming vehicle is detected while traveling with a light distribution shape for traveling, that is, when traveling with a high beam, light directed only to the region of the oncoming vehicle among the regions irradiated by the headlights is emitted. It is possible to reduce in real time. It is possible to always give the driver a field of view close to the high beam, while preventing the oncoming vehicle from being given dazzling light (glare).

In addition, the vehicle changes the direction of travel by operating the steering wheel. When changing the direction of travel, it is preferable from the viewpoint of safety that the headlight for the vehicle can illuminate the direction in which the vehicle is going to travel. A headlight system (called an AFS adaptive front-lighting system) that adjusts the light distribution in the traveling direction according to the steering angle of the steering wheel is becoming generalized.

In such a variable light distribution type headlight system, for example, a light emitting diode device in which a plurality of light emitting diodes (LEDs) are arranged side by side in an array is created, and each light emitting diode conducts / does not conduct (on / off) and conducts. This can be achieved by controlling the input power (and therefore brightness) of the time in real time.

It is provided with an array of a plurality of LED chips arranged in a matrix and independently controllable for lighting, and a projection lens arranged on an optical path of light emitted from the LED chip array, and a lighting pattern of the LED chip array can be obtained. A vehicle headlight device configured to form a predetermined light distribution pattern forward by controlling has been proposed (for example, Patent Document 1).

A specific communication standard such as CAN (controller area network) is used as a network standard for connecting a plurality of devices via a communication line inside an automobile or the like and transmitting / receiving data to each other. Communication by CAN has a limited number of channels, for example, 126 channels can be used to drive a headlight. Since the number of channels is limited by the communication standard, it is desirable to reduce the number of channels used to drive the headlights.

Japanese Unexamined Patent Publication No. 2013-54849

In order to realize a high-definition light distribution pattern, it is desirable to increase the number of light emitting elements arranged in the light distribution region. On the other hand, when trying to control and drive a headlight using a communication standard such as CAN, it is desired that the number of channels be kept within the standard.

According to the examples of the present invention
With the board
A light emitting diode array composed of a plurality of light emitting diodes arranged in a matrix on the substrate,
A first control unit, a second control unit, and a third control unit that control one or more of the light emitting diodes included in each of the plurality of rows in the central portion of the light emitting diode array are included.
Each of the plurality of rows in the central portion of the light emitting diode array includes one light emitting diode controlled by the first control unit and a plurality of light emitting diodes above the first light emitting diode controlled by the second control unit. , A light emitting diode below the light emitting diode of 1 controlled by the 3rd control unit, and the like.
The light emitting diode of 1 is controlled so as to have a higher brightness than a plurality of light emitting diodes controlled by the second control unit and a light emitting diode controlled by the third control unit.
Each of the plurality of light emitting diodes controlled by the second control unit has its own brightness defined by a relative value so that the brightness becomes lower in order from the one closest to the one light emitting diode controlled by the first control unit in one channel. Controlled,
A light emitting diode device is provided.

1A is a light distribution pattern in a desired field of view, FIG. 1B is a schematic plan view of a light emitting diode (LED) array used to form such a light distribution pattern, and FIG. 1C is a layout having an ADB function and the like. It is a block diagram of a light variable type headlight system. 2A and 2B are circuit diagrams showing a wiring example in the light emitting diode array shown in FIG. 1B. FIG. 3A is a plan view schematically showing the configuration of the light emitting diode array according to the embodiment, and FIG. 3B is a circuit diagram of a control drive circuit for one row of light emitting diodes. FIG. 4A is a plan view schematically showing the configuration of the light emitting diode array according to another embodiment, and FIG. 4B is a circuit diagram of a light emitting diode control drive circuit for one row. FIG. 5 is a plan view schematically showing the configuration of the light emitting diode array according to another embodiment. FIG. 6A is a block diagram schematically showing the configuration of a vehicle headlight device using a light emitting diode array, and FIG. 6B is a cross-sectional view schematically showing the configuration of a light source including the light emitting diode array.

LP orientation pattern, LC light distribution center, BP brightness distribution,
BPh horizontal brightness distribution, BPv vertical brightness distribution, H horizontal axis,
V vertical axis, 1 support board, 2 light emitting diode,
28 Light Emitting Diode (LED) Array (Headlight), 21 and 22 Sensors, 31, 32 Detectors, 24 Memory, 26 Central Processing Unit (CPU), 27 Lighting Circuits, 34 Heat Dissipators, 36 Projection Optics,
100 Vehicle headlights, 102 light distribution control unit,
104 forward monitoring unit, 108 in-vehicle camera, 110 radar,
112 vehicle speed sensor, 114 steering angle sensor,
116 GPS navigation, 118 headlight switch,
120 drivers, 200 headlight system,
D light emitting diode, A anode, K cathode,

The explanation starts from the reference technique of the headlight for a vehicle which the present inventor has studied. A light emitting diode array using a GaN-based semiconductor is used as the light source, but it has no limiting meaning. In order to suppress the waste of power and efficiently illuminate the inside of the field, a large number of light emitting diode elements are distributed, and the area where high brightness is desired is illuminated brightly as needed, and high brightness is unnecessary. It is desirable to reduce the brightness of the area and perform illumination having a brightness distribution.

FIG. 1A is a schematic view showing an example of a light distribution pattern in which the brightness is high near the center and the brightness decreases toward the periphery, which is desired for the light flux emitted from the headlamp for a vehicle. A high-intensity light distribution center LC is formed so as to extend in the horizontal direction below the central portion of the light distribution pattern LP facing forward. In vehicle headlights, in order to secure the driver's field of view at night, the light distribution pattern LP generally has the maximum brightness of the light distribution center LC extending in the horizontal direction and gradually decreases toward the periphery. Brightness distribution is desirable. The driver of the vehicle often drives the vehicle with the center of the field of view aligned with the center of the light distribution. The vicinity of the light distribution center LC may be referred to as a central portion.

The luminance distribution BPh parallel to the horizontal (H) axis is shown above the light distribution pattern LP. The maximum brightness is set on the road surface in front, and the brightness decreases as it moves to the left and right. The brightness distribution BPv parallel to the vertical (V) axis at the center of the horizontal axis is shown on the right side of the light distribution pattern LP. The road surface ahead is the light distribution center LC with the maximum brightness. The area below the light distribution center LC includes the road surface on the front side and should be paid attention to as necessary. For example, when there is a step on the road surface, it is preferable to be able to determine the timing of crossing the step. The area below the center of light distribution is less than the maximum brightness, but is still sufficiently bright to obtain information. The brightness drops significantly toward the top. It is a target area that can be roughly recognized, and energy is wasted when illuminated with high brightness.

A semiconductor white light emitting element array can be used as a light source for a vehicle headlamp. A desired brightness distribution is formed by arranging a large number of semiconductor white light emitting elements Q in a matrix and adjusting the brightness of each semiconductor white light emitting element. The semiconductor white light emitting device has, for example, a yellow light emitting phosphor layer above the surface of the blue light emitting diode, and has a function of emitting white light.

Although not restrictive, for example, the GaN-based semiconductor light emitting device disclosed in the column of Examples of Japanese Patent Application Laid-Open No. 2014-232841, which was proposed by the present applicant, is disclosed in the column of Examples of Japanese Patent Application No. 2014-237442. A GaN-based semiconductor light-emitting device, a GaN-based semiconductor light-emitting device disclosed in the column of Examples of Japanese Patent Application No. 2015-84612, and the like can be used.

FIG. 1B is a schematic plan view showing an example of a light emitting diode (LED) array 28 in which a large number of light emitting diode (LEDs) 2 are arranged in a matrix on a support substrate 1. Light emitting diodes 2 having the same shape are arranged in a matrix in the light emitting region to form an array 28. The LED array 28 has, for example, a configuration of (4 to 8) rows x (25 to 60) columns. The study considers a sample of 6 rows x 42 columns. In the figure, the number of columns is simplified and shown as 6 rows × 12 columns. Forty-two LEDs (simplified to 12 in the figure) are lined up in the horizontal (H) direction, and six rows of segments A, B, C, D, E, and F are lined up in the vertical (V) direction. The light distribution center LC is formed in the segment E of the second row from the bottom, which is below the center. Here, horizontal and vertical mean the positional relationship for the orientation reflected when illuminated as a headlight.

As for the light distribution pattern of the vehicle headlight, it is desirable to realize a brightness distribution as shown in FIG. 1A, in which the center of the visual field of the driver is the maximum brightness and the brightness decreases toward the periphery. In order to form the luminance distribution as shown in FIG. 1A, the input power in the central portion is increased, and the input power is decreased toward the periphery. In this way, the headlights are made to form the desired luminance distribution. When both ends in the horizontal direction are on the shoulder of the road, the brightness may be increased even in the peripheral portion, and a brightness distribution that appropriately meets the demand is desired.

The input power is determined by (voltage V) × (current J) × (time T). In the case of a semiconductor light emitting diode, the voltage is almost fixed. The input power is controlled mainly by the product of the current J and the time T. For example, the current can be kept constant, and time control can be performed by pulse width modulation or duty control in frequency modulation. If the duty is increased in the central portion, the input power can be increased, and if the duty is decreased in the peripheral portion, the input power can be decreased. The chromaticity can also be adjusted by controlling the instantaneous current density. Even if the instantaneous current density is increased, the same power can be obtained by decreasing the time.

FIG. 1C is a block diagram showing a schematic configuration of a headlight system. The headlight system 200 includes left and right vehicle headlights 100, a light distribution control unit 102, a front monitoring unit 104, and the like. The vehicle headlight 100 includes a light source including a matrix LED, a projection lens, and a lamp body for accommodating them.

The front monitoring unit 104, to which various sensors such as the in-vehicle camera 108, the radar 110, and the vehicle speed sensor 112 are connected, processes the imaged data acquired from the sensors and performs image processing on the vehicle in front (oncoming vehicle or preceding vehicle) or other road brilliance. Detects objects and lane markings, and calculates data required for light distribution control, such as their attributes and positions. The calculated data is transmitted to the light distribution control unit 102 and various in-vehicle devices via the in-vehicle LAN or the like.

The light distribution control unit 102 to which the vehicle speed sensor 112, the steering angle sensor 114, the GPS navigation 116, the headlight switch 118, etc. are connected has the attributes of the on-road bright object (oncoming vehicle, preceding vehicle) sent from the front monitoring unit 104. Based on the vehicle, reflector, road lighting), its position (front, side), and vehicle speed, the light distribution pattern (brightness distribution) corresponding to the driving scene is determined. The light distribution control unit 102 determines the control content (turning on / off, input power, etc.) of each LED of the matrix LED, which is necessary to realize the light distribution pattern. The driver 120 converts the information on the control amount from the light distribution control unit 102 into commands corresponding to the operations of the drive device and the light distribution control element, and controls them.

Vehicle headlamps need to form a brightness distribution in which the brightness is high at the center (center of light distribution) and the brightness decreases toward the periphery. In the case of a vehicle headlamp using a semiconductor light emitting element array, it is possible to adjust the brightness by controlling the driving power of each semiconductor light emitting element to form a desired brightness distribution.

FIG. 2A is a circuit diagram showing a wiring example of the semiconductor light emitting device array. The cathodes of the six light emitting diodes D1 to D6 arranged in the row direction are connected to the cathode common wiring K, and the anodes A1 to A6 are individually wired. For example, independently controllable current sources are connected to the six anodes A1 to A6.

FIG. 2B is a circuit diagram showing another wiring example of the semiconductor light emitting device array. Six light emitting diodes D1 to D6 arranged in the column direction are connected in series, the cathode of the light emitting diode D1 in the bottom row is connected to the cathode wiring K, and the anodes A1 to A6 of the light emitting diodes D1 to D6 in all rows are independent of each other. It is wired to. A current can be selectively supplied to an arbitrary light emitting diode to cause light emission, and a current can be supplied to a series connection and the anode and cathode of the arbitrary light emitting diode are short-circuited to turn off the light emitting diode. can. Using these wirings, it is possible to selectively supply a drive current to each light emitting diode to perform arbitrary light emission control. The anode and cathode may be connected in reverse.

Consider the case where the light emitting diode array shown in FIG. 1B includes 6 rows and 42 columns of light emitting diode elements. When all the light emitting diode elements are driven independently, the object to be driven is 6 × 42 = 252 elements. When trying to drive with a CAN system, the maximum number of channels that can be used is 144, which is significantly insufficient.

FIG. 3A is a plan view showing the configuration of the light emitting diode array 28 according to the embodiment. The same number of light emitting diodes 2 as in FIG. 1B are arranged in a matrix on the support substrate 1. The rows of light emitting diodes arranged in the horizontal direction are called L1, L2, L3, L4, L5, L6 from the bottom. The second row from the bottom, the light emitting diode row L2, constitutes the light emitting center LC. The light emitting diode of the light emitting center LC has high brightness, and it is desirable to control it individually with high definition. The light emitting diode row L1 at the bottom illuminates the area through which the vehicle passes after a short time, and is preferably individually controllable in order to obtain sufficient information. Therefore, 84 light emitting diodes of L1 and L2 in the bottom two rows of the six rows are individually driven independently.

The brightness of the light emitting diodes of L3, L4, L5, and L6 in the third and higher lines from the bottom is the brightness that gradually attenuates from the brightness of the light emitting diode at the center of light emission. High-precision brightness control is not required so much. For example, there is not much problem even if it is specified by a value relative to the maximum brightness of the light emitting diode at the center of light emission. If the brightness of the light emitting diodes of L3, L4, L5, L6 (collectively referred to as G3) in the third row or more from the bottom is specified by a relative value for each column (C1, C2, C3, ...), there are four. The light emitting diode can be controlled by one channel. The upper 4 rows and 42 columns of light emitting diodes can be controlled by 42 channels.

When 84 channels are used to drive 84 light emitting diodes of L1 and L2 and 42 channels are used to drive 168 light emitting diodes of G3 (L3 to L6), all channels used are 126 channels and 144 channels of CAN. It fits within the standard of.

FIG. 3B is a circuit diagram showing a control drive system for one row. One row contains the six light emitting diodes D1 to D6 shown on the right. The drive circuit DR1 controls the drive of the light emitting diode D1 based on the given command. Although one signal line is shown as a signal line for giving an instruction, any instruction included in one channel may be used. The drive circuit DR2 controls the drive of the light emitting diode D2 having the maximum brightness in the row based on the given command. Although one signal line is shown as a signal line for giving an instruction, any instruction included in one channel may be used.

When the light emitting diode array has the wiring as shown in FIG. 2A, the drive circuit DR3 is connected to all the independent wirings A3 to A6. The light emission / extinguishing control is collectively transmitted through the drive circuit DR3 at the same time. When the light emitting diode array has the wiring as shown in FIG. 2B, it does not matter because it is connected only to the independent wiring A6 which is the anode of the light emitting diode farthest from the common cathode in the circuit. The independent wirings A5, A4, and A3 do not have to be controlled by any drive circuit, and since D3 to D6 are connected in series, light emission / extinguishing is collectively controlled by a signal to the independent wiring A6. Will be done. Even in this case, the drive circuit DR3 collectively controls the light emitting diodes connected by a plurality of independent wirings.

As described above, since the drive circuit DR3 is connected to the light emitting diodes connected to more independent wiring than the DR1 and DR2, the number of channels used is suppressed.

In this embodiment, each row is connected to the drive circuit as described above.

FIG. 4A is a plan view showing the configuration of the light emitting diode array 28 according to another embodiment. The same number of light emitting diodes 2 as in FIG. 3A are distributed on the support substrate 1. The points different from FIG. 3A will be mainly described. The light emitting diode rows C17 to C26 shown in the central portion are actually 10 rows of light emitting diode trains, and the three rows L1, L2, and L3 from the bottom are individually controlled. The fourth and higher rows L4, L5, and L6 from the bottom are collectively controlled for each column. L1 to L6 are collectively controlled from both left and right sides, L1 is independently controlled from C2 to C4, C39 to C41, and L2 to L6 are controlled collectively from C2 to C16, and L1 and L2 are independently controlled from C27 to C38. , L3 to L6 are collectively controlled.

Looking at each column in the row direction, the number of light emitting diodes that are simultaneously controlled is larger in the columns on the left and right than in the center. In that column in the center portion to increase the number of control circuits connected than columns on the left and right, more control than the left and right of the central portion even in the horizontal direction while suppressing the increase in the number of channels as in this embodiment It is possible to do.

FIG. 4B is a circuit diagram showing a control drive system for one row in the central portion. Each of the 10 rows in the center of the light emitting diode array is controlled by being divided into 4 parts, and a finer light distribution pattern can be realized. One row contains the six light emitting diodes D1 to D6 shown on the right. The drive circuit DR1 controls the drive of the light emitting diode D1 based on the given command. Although one signal line is shown as a signal line for giving an instruction, any instruction included in one channel may be used. The drive circuit DR2 controls the drive of the light emitting diode D2 having the maximum brightness in the row based on the given command. The drive circuit DR3 controls the drive of the light emitting diode D3 based on the given command. Each signal line is shown as a signal line for giving an instruction, but any instruction included in one channel may be used.

The case of a light emitting diode array in which light emitting diodes having the same shape are arranged in 6 rows and 42 columns has been described, but these shapes and numbers have no limiting meaning. When CAN is used, the number of channels used is limited by a maximum of 144, but the number of elements controlled collectively is not limited. For example, the number of element rows arranged in the vertical direction may be 7 or more. A light emitting diode in the peripheral portion may be arranged in the lower part of the field of view in the central portion. For example, the third row from the bottom may be the maximum luminance line, and the bottom row may be the peripheral portion, which may be controlled by a value relative to the luminance of the central portion.

Each row of the light emitting diode array has been described as being controlled independently, but is not limiting. It is also conceivable to collectively control a plurality of columns in the peripheral portion. FIG. 5 shows a case where the central portions C4 to C39 of the peripheral portion are controlled independently for each row, and a plurality of rows are collectively controlled in the block regions BL1 and BL2 at the left and right ends of the peripheral portion. BL1 and BL2 are regions formed by a plurality of rows and a plurality of columns. Although the block area is formed by three columns, a block area that is controlled by two columns may be provided between the block area and the central column that is controlled for each column. In this way, by increasing the number of rows that can be controlled collectively as it goes to the left and right from the center, it is possible to control the center more finely than the left and right in the horizontal direction while suppressing an increase in the number of channels.

In order to move the light distribution center to the left and right, it is preferable that the pitch in the horizontal (horizontal) direction of the light emitting diode matrix is constant. The AFS function can be preferably realized. Although the case of using light emitting diodes having the same shape has been described, it is also possible to use light emitting diodes having different areas. If a light emitting diode having a large area and a light emitting diode having a small area are connected in series, the current density in the light emitting diode having a small area becomes higher than the current density in the light emitting diode having a large area, and the brightness becomes high. By forming a plurality of light emitting diodes having a larger area as the distance from the center of light emission increases and connecting them in series, it is possible to form a luminance distribution in which the brightness decreases as the distance from the center of light emission increases with one drive current. By connecting a plurality of light emitting diodes having different areas in parallel, the larger the area of the light emitting diodes, the higher the brightness can be formed. It is also possible to connect a plurality of light emitting diodes in series, parallel, and series-parallel to form various luminance distributions.

FIG. 6A is a block diagram schematically showing the configuration of a vehicle headlamp. The external sensor 21 includes a camera, a radar, and the like, and mainly captures information on the preceding vehicle, the oncoming vehicle, and the like in front, and the detection unit 31 detects the information on the preceding vehicle such as the oncoming vehicle and the oncoming vehicle. The in-vehicle sensor 22 takes in the own vehicle signal such as the own vehicle speed signal and the steering angle signal from the signal wiring in the vehicle, and the detection unit 32 detects the own vehicle information. The memory 24 includes a read-only memory (ROM), a random access memory (RAM), and the like, and stores information necessary for controlling the headlight system, such as headlamp characteristics and external conditions. The lighting circuits 27A and 27B supply pulse power for driving the headlights 28A and 28B. Each of the headlights 28A and 28B includes a semiconductor light emitting diode (LED) array.

The central processing unit (CPU) 26 is based on information such as LED array standards and desirable brightness distribution supplied from the memory 24 and information such as the external environment supplied from the detection units 31 and 32. Various calculations are performed to determine the drive current pulse that drives the headlights 28A and 28B. The central processing unit 26 can perform ADB that suppresses the light toward the oncoming vehicle based on the information of the vehicle in front and the like, and increases the illumination light to the area to be moved based on the signal of the own vehicle and the like. AFS and the like can be performed.

FIG. 6B schematically shows the configuration of the mounting portion of the LED array 28. The LED array 28 is supported by the heat radiating unit 34, and the generated irradiation light is projected to the front of the vehicle via the projection optical unit 36 such as a reflector and a lens.

According to the present invention, it is possible to meet the demands of various light distribution designs, and it is also advantageous in terms of manufacturing cost because a common light emitting diode array can be used, and the number of channels to be used is suppressed. There is.

Although described above with reference to Examples, these do not limit the present invention. For example, the light emitting diode (LED) may be a semiconductor laser. Since a semiconductor laser is also a diode, the concept of LED includes a laser. It will be obvious to those skilled in the art that various other changes, improvements, combinations, etc. are possible.

Claims (10)

With the board
A light emitting diode array composed of a plurality of light emitting diodes arranged in a matrix on the substrate,
A first control unit, a second control unit, and a third control unit that control one or more of the light emitting diodes included in each of the plurality of rows in the central portion of the light emitting diode array are included.
Each of the plurality of rows in the central portion of the light emitting diode array includes one light emitting diode controlled by the first control unit and a plurality of light emitting diodes above the first light emitting diode controlled by the second control unit. , A light emitting diode below the light emitting diode of 1 controlled by the 3rd control unit, and the like.
The light emitting diode of 1 is controlled so as to have a higher brightness than a plurality of light emitting diodes controlled by the second control unit and a light emitting diode controlled by the third control unit.
Each of the plurality of light emitting diodes controlled by the second control unit has its own brightness defined by a relative value so that the brightness becomes lower in order from the one closest to the one light emitting diode controlled by the first control unit in one channel. Controlled,
Light emitting diode device. The plurality of light emitting diodes are wired in a controllable manner by a plurality of independent wires.
The second control unit is characterized in that it collectively controls the lighting / extinguishing of a plurality of light emitting diodes that can be controlled by a plurality of independent wirings.
The light emitting diode device according to claim 1. The second control unit is collectively connected to the plurality of independent wirings, and is characterized in that it controls lighting / extinguishing at the same time.
The light emitting diode device according to claim 2. The first control unit and the plurality of light emitting diodes controlled by the second control unit are connected in series and have a common anode or cathode.
The independent wiring is individually connected to the cathode or anode of the light emitting diode.
The second control unit is connected to the independent wiring of the light emitting diode farthest from the common anode or cathode on the circuits of the plurality of controllable light emitting diodes.
The light emitting diode device according to claim 2. In the light emitting diode array arranged in the matrix,
The number of light emitting diodes controlled by the second control unit in the central row is less than the number of light emitting diodes controlled by the second control unit in the left-right row.
The light emitting diode device according to any one of claims 1 to 4. The second control unit includes a portion that simultaneously controls a plurality of light emitting diodes arranged in a plurality of different rows.
The light emitting diode device according to any one of claims 1 to 5. Each of the plurality of light emitting diodes has a phosphor film and emits white light, and the light emitting diode device constitutes a headlight for a vehicle.
The light emitting diode device according to any one of claims 1 to 6. In addition, a sensor that monitors the front and
A pattern control unit that controls the orientation pattern formed by the light emitting diode array based on the signal from the sensor.
including,
The light emitting diode device according to any one of claims 1 to 7. The pattern control unit reduces the light directed to the selected region.
The light emitting diode device according to claim 8. The light emitting diode array is controlled so that the light emitting diode near the center has a higher brightness than the light emitting diode near the outer periphery so as to form a brightness distribution in which the brightness decreases from the center to the periphery. ,
The light emitting diode device according to claim 1.

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