Lighting control device

Abstract

The purpose of the present disclosure is to achieve an increase in light sources for an on-board lamp and to achieve sophistication or diversification of lighting functions. A lighting control device (101) according to the present disclosure comprises: a lighting control unit (11) that determines the modulation states of a plurality of light sources; and a communication unit (12) that is interposed between the lighting control unit (11) and the plurality of light sources and that transmits, through serial communication, instructions regarding the modulation states of the plurality of light sources. The communication unit (12) transmits and receives information by dividing the plurality of light sources into a plurality of groups according to the priorities of the light sources and sequentially selecting, from among the plurality of groups, a communication destination for each communication cycle of the serial communication. The number of light sources constituting each group of the plurality of groups is, for light sources constituting each group and having a high priority, smaller than the number of light sources having a low priority.

Description

Light control device

[0001] The present disclosure relates to lighting control of an in-vehicle lamp.

[0002] Vehicles such as automobiles and motorcycles are equipped with lighting fixtures such as headlights and turn signal lights. The lighting fixtures are configured with a light source and a light source control unit that drives the light source. In recent years, as the number of functions required of lighting fixtures (hereinafter referred to as "lighting functions") has increased, the number of light sources installed in lighting fixtures and the number of light source control units that control the light sources have also increased.

[0003] These light source control units are connected to a light control device that controls the lights of the lighting fixtures, and communicate with the light control device sequentially via serial communication.

[0004] International Publication No. 2020 / 208818

[0005] Patent Document 1 discloses a light control device to which multiple light sources are connected. Here, it is assumed that information is exchanged between the light control device and the light sources via serial communication. As the number of light sources increases, the number of light source control units that drive the light sources also increases. Therefore, it takes a long time for the light control device to communicate with all of the light source control units.

[0006] For example, assume that one communication between the light control unit and an arbitrary light source control unit requires 10 milliseconds (hereinafter, "ms"). In this case, if there are two light source control units, the time required for all the installed light source control units to be contacted (hereinafter, referred to as the "control cycle") is 20 ms. If there are six light source control units, the control cycle is 60 ms. If 20 light sources are installed in a vehicle, the control cycle for contacting all 20 light source control units reaches 200 ms. This means that the light control unit can control each light source only once every 200 ms, or can read information from each light source only once every 200 ms.

[0007] On the other hand, the lighting control unit may be required to control the light source in a short time or read information from the light source in a short time according to the lighting functions that are becoming more advanced or diversified. Also, the lighting control unit may be required to increase the number of times that information is read from the light source per unit time, i.e., the read frequency, to ensure the reliability of the read information.

[0008] As such, it is difficult to simultaneously increase the number of light sources and provide more advanced or more diverse lighting functions. The present disclosure has been made to solve the above problems, and aims to simultaneously increase the number of light sources in an automotive lamp and provide more advanced or more diverse lighting functions.

[0009] The lighting control device disclosed herein is a lighting control device that controls lighting using multiple light sources mounted on a vehicle, and includes a lighting control unit that determines the dimming state of the multiple light sources, and a communication unit that is interposed between the lighting control unit and the multiple light sources and transmits instructions for the dimming state of the multiple light sources via serial communication, and the communication unit divides the multiple light sources into multiple groups according to their priority, and selects a communication destination from the multiple groups in order for each communication cycle of the serial communication to exchange information, and the number of light sources that make up each group is smaller for light sources with higher priority than for light sources with lower priority.

[0010] According to the lighting control device of the present disclosure, by grouping a plurality of light source control units according to priority, it is possible to set a different control cycle for each group, thereby enabling both an increase in the number of light sources in an automotive lamp and an increase in the sophistication or diversification of lighting functions. Objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0011] 1 is a block diagram showing the configuration of a light control device according to embodiment 1. FIG. 2 is a diagram showing light control by a light control device of a comparative example. FIG. 3 is a diagram showing grouping of luminaires in light control according to embodiment 1. FIG. 4 is a diagram showing light control according to embodiment 1. FIG. 5 is a diagram showing grouping of luminaires in light control according to a modified example of embodiment 1. FIG. 6 is a diagram showing light control according to a modified example of embodiment 1. FIG. 7 is a block diagram showing the configuration of a light control device according to embodiment 2. FIG. 8 is a diagram showing the hardware configuration of a light control device. FIG. 9 is a diagram showing the hardware configuration of a light control device.

[0012] <A. Embodiment 1> <A-1. Configuration> Fig. 1 is a block diagram showing the configuration of a light control device 101 according to embodiment 1. The light control device 101 receives instructions from a light instruction device 3 and controls the lighting of a lamp 2 mounted on a vehicle 100. The lamp 2 is an in-vehicle lamp. In Fig. 1, the light control device 101 and the light instruction device 3 are mounted on the vehicle 100 to be controlled.

[0013] In this embodiment, the lighting fixture 2 is equipped with six light sources A, B, C, D, E, and F as light sources, and the light control device 101 controls the dimming state of these light sources. However, the number of light sources controlled by the light control device 101 is not limited to six. In the following description, when referring to light sources A, B, C, D, E, and F without specifying them individually, they will be referred to as light sources. Furthermore, the exchange of information between the communication unit 12 and the light sources and the exchange of information between the communication unit 12 and the light source control unit 21 are equivalent and no particular distinction will be made.

[0014] Here, the dimming state of the light source controlled by the light control device 101 includes a light source being turned on, turned off, or turned on at intermediate brightness.

[0015] The light instruction device 3 is a host computer of the light control device 101. The light instruction device 3 gives instructions to the light control device 101 regarding the dimming state, lighting mode, or light distribution of the light sources 22 included in each lamp 2, such as low beam, high beam, turn signal lighting, light distribution control including glare suppression, spot illumination by auxiliary lights, and turn markers when turning right or left.

[0016] Each of the light sources A to F includes a light source device 22 and a light source control unit 21 that drives the light source device 22. The number of the light source device 22 may be one or more.

[0017] The light control device 101 is configured to include a light control unit 11, a communication unit 12, and a failure detection unit 13. The light control unit 11 receives instructions from the light instruction device 3, and creates instruction information for controlling the dimming state of the light source 22 based on the instructions.

[0018] The communication unit 12 performs serial communication with the plurality of light source control units 21. The communication unit 12 receives instruction information created by the light control unit 11 and transmits this instruction information to the light source control unit 21 of each light source via serial communication. The communication unit 12 also receives information on the state of the light source from the light source control unit 21 via serial communication. It is assumed that each exchange of information between the communication unit 12 and the light source control unit 21 requires 10 ms.

[0019] The light source control unit 21 receives instruction information from the communication unit 12 and controls the dimming state of the light source device 22 based on this instruction information. When there are multiple light source devices 22, the light source control unit 21 may not only uniformly and equally control the dimming states of the multiple light source devices 22, but may also individually control the dimming states according to the instruction information from the lamp control unit 11. For example, when the light source device 22 is made up of multiple light sources arranged in a matrix, the light source control unit 21 may dim or turn off some of the light sources to reduce glare. However, for simplicity, the following description will be given assuming that the light source device 22 is a single light source. The light source device 22 may be, for example, a semiconductor light source represented by an LED (Light Emitting Diode), a liquid crystal, an organic EL (Electro-Luminescence), a laser, or any other light source that can be controlled by communication.

[0020] The fault detection unit 13 acquires information about the state of the light source received by the communication unit 12 and determines whether the light source is faulty based on this information. This fault determination requires reliability. Therefore, the fault detection unit 13 does not immediately determine that the light source is faulty when the information about the state of the light source satisfies a predetermined fault condition once, but rather determines that the light source is faulty when, for example, the fault condition is met multiple times in succession.

[0021] <A-2. Operation> Figure 2 is a diagram showing light control by a light control device of a comparative example. The light control of the comparative example will be described below with reference to Figure 2. In Figure 2, communication cycle 1 refers to the first communication, communication cycle 2 refers to the second communication, and so on. In communication cycle 1, information is exchanged between the communication unit 12 and light source A. This exchange of information takes 10 ms. In communication cycle 2, information is exchanged between the communication unit 12 and light source B. Information is exchanged sequentially thereafter in the same manner, and when communication cycle 6 ends, the exchange of information with light sources A, B, C, D, E, and F has been completed.

[0022] Therefore, in the comparative example, when there are six light sources, the light control device can only exchange information with each light source once every 60 ms. Therefore, when 20 light sources are prepared due to the advanced or diversified functions of the vehicle lighting fixture, it takes 200 ms for information to be exchanged with each light source once. In other words, the exchange of information with each light source, i.e., control and status detection, is only performed once every 200 ms.

[0023] However, light sources can be equipped with a wide variety of functions, and their priorities are not uniform. For example, the exchange of light source information related to functional safety must be completed in a short time and frequently to ensure reliability.

[0024] 3 and 4 are diagrams showing light control by the light control device 101 of this embodiment. The light control of this embodiment will be described below with reference to FIGS. 3 and 4. As shown in FIG. 3, the communication unit 12 divides light sources into different groups according to their priority. Light sources A and B, which have a high priority, belong to group (1), and light sources C, D, E, and F, which have a lower priority than group (1), belong to group (2). Light sources A and B, which have a high priority, are, for example, lamps that emit low beams related to functional safety.

[0025] 4 , the communication unit 12 exchanges information alternately with the light source control units 21 installed in the light sources of groups (1) and (2) during each communication cycle. That is, the communication unit 12 exchanges information with the light source control units 21 of the light sources belonging to group (1) during communication cycle 1, and exchanges information with the light source control units 21 of the light sources belonging to group (2) during communication cycle 2. Specifically, the communication unit 12 exchanges information with the light source control unit 21 of light source A during communication cycle 1, which is the first communication with group (1), and exchanges information with the light source control unit 21 of light source C during communication cycle 2, which is the first communication with group (2). Furthermore, the communication unit 12 exchanges information with the light source control unit 21 of light source B during communication cycle 3, which is the second communication with group (1), and exchanges information with the light source control unit 21 of light source D during communication cycle 4, which is the second communication with group (2).

[0026] In this way, the communication unit 12 sequentially exchanges information with the light source controllers 21 of light sources A and B belonging to group (1) in communication cycles 1, 3, and 5, completing one cycle in four communication cycles (4 cycles = 40 ms). Here, the cycle required to exchange information with all light source controllers 21 belonging to one group is referred to as a control cycle. In other words, the control cycle for group (1) is four cycles. For example, the communication unit 12 exchanges information with light source A, and then exchanges information with light source A again, requiring four communication cycles (4 cycles = 40 ms).

[0027] Similarly, the communication unit 12 exchanges information with the light source controllers 21 of light sources C, D, E, and F belonging to group (2) in communication cycles 2, 4, 6, 8, and 10, successively. Thus, the communication unit 12 completes the exchange of information with the light source controllers 21 of light sources C, D, E, and F belonging to group (2) in eight communication cycles (8 cycles = 80 ms). In other words, the control cycle for group (2) is eight cycles. For example, it takes eight communication cycles (8 cycles = 80 ms) for the communication unit 12 to exchange information with light source C and then exchange information with light source C again.

[0028] In this way, the control cycle of each group is determined by (the number of groups) x (the number of light source control units belonging to each group). Therefore, the communication unit 12 can shorten the control cycle of the high-priority group by setting the number of light source control units 21 belonging to a group with a high communication priority to be less than the number of light source control units 21 belonging to a group with a low communication priority.

[0029] Light sources A and B belonging to group (1) emit low beams related to functional safety. It is desirable that the fault detection unit 13 determines that light sources A and B have a fault when information about these light sources meets the fault condition multiple times, for example, twice consecutively. In the above example, the control cycle for group (1) is 4 cycles = 40 ms, so the fault detection unit 13 performs fault determination for light sources A and B at 80 ms intervals. On the other hand, the control cycle for group (2) is 8 cycles = 80 ms, so the fault detection unit 13 requires 160 ms to perform fault determination for light sources C, D, E, and F belonging to group (2).

[0030] The light control device 101 according to the first embodiment controls lights using a plurality of light sources A to F mounted on a vehicle. The light control device 101 includes a light control unit 11 that determines the dimming state of the light sources A to F, and a communication unit 12 that is located between the light control unit 11 and the light sources A to F and transmits dimming state instructions for the plurality of light sources via serial communication. The communication unit 12 divides the light sources A to F into a plurality of groups according to their priorities, and selects a communication destination from the plurality of groups in turn for each communication cycle of the serial communication to exchange information. The number of light sources constituting each of the plurality of groups is smaller for light sources with higher priority than for light sources with lower priority. With the above configuration, the light control device 101 can change the dimming state of the light sources in a short time by shortening the control cycle of the light source control unit 21 for light sources with higher priority. Therefore, even if the number of light sources increases and their functions become more sophisticated or diverse, both of these can be achieved. Furthermore, according to the lighting control device 101, by shortening the control cycle of the high-priority light source control unit 21, the state of the high-priority light source can be detected with high frequency, and highly reliable judgments can be made.

[0031] In the above description, the lighting fixture 2 is described as including a plurality of light sources A to F. However, this is not a limitation, and the lighting fixture 2 may have only one light source and there may be a plurality of such lighting fixtures 2. In other words, there may be either a single lighting fixture 2 or a plurality of lighting fixtures 2, as long as one light control unit 11 exchanges information with a plurality of light source control units 21. Furthermore, the lighting fixture 2 may be provided with a light control unit 11A and a light control unit 11B, and the light control unit 11A may exchange information with four light source control units 21, while the light control unit 11B may exchange information with six light source control units 21; such modifications are free to be made.

[0032] <A-3. Modifications> In the above description, the communication unit 12 divided the light sources into two groups, but may divide them into three or more groups. Also, the communication unit 12 set the priority of the light sources into two levels, high and low, but may set it into three levels, high, medium, and low. Also, the communication unit 12 may set the same priority for some groups. For example, the communication unit 12 may divide the light sources into four groups and set the priority of each group to high, medium, medium, and low. Alternatively, the communication unit 12 may divide the light sources into three groups and set the priority of each group to high, high, and low.

[0033] Fig. 5 shows such a modified grouping. In the example of Fig. 5, there are light sources A, B, C, D, E, F, and G. Of these, light sources A and B are grouped into a high-priority group (1), light sources C and D are grouped into a high-priority group (2), and light sources E, F, and G are grouped into a low-priority group (3). Fig. 6 is a diagram showing the communication timing of each light source 2 when grouped as shown in Fig. 5. The control cycle for groups (1) and (2) is 6 cycles, and the control cycle for group (3) is 9 cycles.

[0034] In the above description, the light source related to functional safety has a high priority. However, if there is a light source with a higher priority than the light source related to functional safety, the light source related to functional safety may have a medium priority. It is sufficient that a plurality of light sources are divided into a plurality of groups, and at least one of these groups is assigned a priority different from the other groups.

[0035] The communication unit 12 may assign a higher priority to light sources that require a shorter function than to light sources that require a longer function. Light sources that require a shorter function include light sources that constitute sequential turn signals. Lighting control is performed on the light sources that constitute sequential turn signals so that they appear to change dynamically over time. Light sources that constitute sequential turn signals are required to have a shorter control cycle so that they appear to change smoothly. On the other hand, side marker lights only need to flash slowly. Therefore, the communication unit 12 may assign light sources that constitute sequential turn signals to a high-priority group and other light sources, including side marker lights, to a low-priority group. Note that the number of light sources that constitute a high-priority group is smaller than the number of light sources that constitute a low-priority group. As a result, the light sources that constitute sequential lights are smoothly turned on in sequence, and the dimming state of the light sources that constitute side marker lights is controlled more slowly than that of the sequential lights.

[0036] The communication unit 12 may set a higher priority for light sources having functions requiring high reliability than for light sources having functions requiring lower reliability, thereby enabling the fault detection unit 13 to frequently detect the status of light sources having functions requiring high reliability.

[0037] The communication unit 12 may set the priority of the light source based on the type of information acquired from the light source. For example, there is a demand to acquire information about a light source failure in a short time, but because the temperature of the light source device 22 does not change in a short time, there is little demand to acquire information about the temperature of the light source device 22 in a short time. Therefore, the communication unit 12 may set the priority of acquiring information about a failure to be higher than the priority of acquiring information about the temperature.

[0038] <B. Second Embodiment> Fig. 7 is a block diagram showing the configuration of a light control device 102 according to a second embodiment. In addition to the configuration of the light control device 101 according to the first embodiment, the light control device 102 includes an EEPROM (Electrically Erasable Programmable Read-Only Memory) 14 as a storage unit.

[0039] The EEPROM 14 stores group information indicating to which of a plurality of groups each of the light source control units 21 of the plurality of light sources belongs. The communication unit 12 divides the plurality of light source control units 21 into a plurality of groups based on the group information stored in the EEPROM 14.

[0040] As the number of light sources increases and their functions become more advanced or diverse, the priority of the light sources changes. Furthermore, the number and functions of light sources, and the priority, change depending on the grade or destination of the vehicle 100. To accommodate these changes, the light control device 102 stores group information and includes an EEPROM 14 that can rewrite the stored group information.

[0041] There are roughly two methods for rewriting the group information in the EEPROM 14. If it is known at the manufacturing stage of the light control device 102 what light sources the light control device 102 will be connected to, the manufacturer can store the group information in the EEPROM 14 at the manufacturing stage of the light control device 102. On the other hand, if a lighting fixture manufacturer wants to freely connect light sources to the light control device 102, the manufacturer of the light control device 102 can store default group information in the EEPROM 14 at the manufacturing stage of the light control device 102 and ship it. Thereafter, the lighting fixture manufacturer can rewrite the default group information stored in the EEPROM 14. In this case, the light control device 102 can be shared for a wide variety of vehicles, which makes management easier for the manufacturer of the light control device 102 and offers cost benefits.

[0042] The light control device 102 according to the second embodiment includes an EEPROM 14 as a storage unit that stores group information indicating to which of a plurality of groups each of a plurality of light source control units 21 belongs. The communication unit 12 divides the plurality of light source control units 21 into a plurality of groups based on the group information. The EEPROM 14 is rewritable of the group information. With the above configuration, even if the number of light sources connected to the light control device 102 changes or the priority of the light sources differs, it is possible to accommodate this by pre-writing the group information to be stored in the EEPROM 14 or by rewriting the stored group information. Note that "the group information stored in the storage unit is rewritable" means both pre-writing the group information to be stored in the storage unit and rewriting the group information stored in the storage unit.

[0043] <C. Hardware Configuration> The light control unit 11, communication unit 12, fault detection unit 13, and EEPROM 14 in the above-described light control devices 101, 102 are realized by a processing circuit 81 shown in FIG. 8. That is, the processing circuit 81 includes the light control unit 11, communication unit 12, fault detection unit 13, and EEPROM 14 (hereinafter referred to as the light control unit 11, etc.). Dedicated hardware may be applied to the processing circuit 81, or a processor that executes a program stored in memory may be applied. The processor may be, for example, a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor), etc.

[0044] When the processing circuit 81 is dedicated hardware, the processing circuit 81 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Each function of the light control unit 11 and other units may be realized by a plurality of processing circuits 81, or the functions of the units may be collectively realized by a single processing circuit.

[0045] When the processing circuit 81 is a processor, the functions of the light control unit 11 and the like are realized by a combination of software, firmware, or software and firmware. The software is written as a program and stored in a memory. As shown in FIG. 9 , the processor 82 applied to the processing circuit 81 realizes the functions of each unit by reading and executing the program stored in the memory 83. The memory 83 may be, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM), a hard disk drive (HDD), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, a digital versatile disk (DVD), and a drive device for the same, or any storage medium that will be used in the future.

[0046] The above describes a configuration in which each function of the light control unit 11, etc. is realized either by hardware or software, etc. However, the present invention is not limited to this, and a configuration in which part of the light control unit 11, etc. is realized by dedicated hardware and another part is realized by software, etc. For example, the function of the communication unit 12 can be realized by a processing circuit as dedicated hardware, and the other functions can be realized by the processing circuit 81 as the processor 82 reading and executing programs stored in the memory 83.

[0047] As described above, the processing circuit can realize each of the above functions by hardware, software, or a combination of these.

[0048] It is possible to freely combine the above-described embodiments or their modifications, and to modify or omit the embodiments as appropriate. The above description is an example in all respects. It is understood that countless modifications not illustrated can be envisioned.

[0049] 2 Lighting fixture, 3 Light indicator device, 11 Light control unit, 12 Communication unit, 13 Fault detection unit, 14 EEPROM, 21 Light source control unit, 22 Light source device, 81 Processing circuit, 82 Processor, 83 Memory, 100 Vehicle, 101, 102 Light control device.

Claims

1. A lighting control device that controls lighting using multiple light sources mounted on a vehicle, comprising: a lighting control unit that determines the dimming state of the multiple light sources; and a communication unit that is interposed between the lighting control unit and the multiple light sources and transmits instructions for the dimming state of the multiple light sources via serial communication, wherein the communication unit divides the multiple light sources into multiple groups according to their priorities, and selects a communication destination from the multiple groups in order for each communication cycle of the serial communication to exchange information, and the number of light sources that make up each of the multiple groups is smaller for light sources with higher priorities than for light sources with lower priorities.

2. A light control device according to claim 1, further comprising a memory unit that stores group information indicating to which of the plurality of groups the plurality of light sources belongs, the communication unit divides the plurality of light sources into the plurality of groups based on the group information, and the memory unit is capable of rewriting the group information.

3. The light control device according to claim 1, wherein the priority of the light source is higher when the required time for the function of the light source is short than when it is long.

4. The light control device according to claim 1, wherein when the requirement for reliability of the function of the light source is high, the priority of the light source is higher than when the requirement is low.

5. The light control device according to claim 1, wherein a group among the plurality of groups to which the light source related to functional safety belongs has a higher priority than a light source to which at least one of the other groups belongs.

6. The light control device according to claim 1, wherein a group among the plurality of groups to which the light source related to the function of changing the dimming state in a short time belongs has a higher priority than a light source to which at least one of the other groups belongs.

7. The light control device according to claim 1, wherein the communication unit receives predetermined information from the light source of each of the plurality of lighting fixtures.

8. The light control device according to claim 7, wherein the predetermined information is information relating to a failure or temperature of the light source.

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