Illumination device and control method

Abstract

An illumination device (100) is provided with: a light source (110) having a plurality of light-emitting elements (111) arranged in an array; a projection lens (120) for projecting light emitted by the light source (110); an acquisition unit (130) for acquiring input data; a control unit (140) for individually controlling the current supplied to each of the plurality of light-emitting elements (111); and a detection unit (150) for detecting the temperature of the light source (110). The control unit (140) determines whether the temperature of the light source (110) satisfies a predetermined condition. When it is determined that the temperature of the light source (110) satisfies the predetermined condition, the control unit (140) selects, on the basis of the characteristics of the input data acquired by the acquisition unit (130), a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements (111), and adjusts the amount of current supplied to each of the plurality of light-emitting elements (111) on the basis of the selected current adjustment algorithm.

Description

Lighting device and control method

[0001] The present invention relates to a lighting device and a method for controlling a lighting device.

[0002] BACKGROUND ART There is known a device that includes a light source having a plurality of LEDs (Light Emitting Diodes) arranged in an array and that can cause the plurality of LEDs to emit light in a predetermined emission pattern (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2020-95963

[0004] When a plurality of LEDs of a light source are arranged in an array, the light source is likely to be subjected to a thermal load, which tends to reduce the thermal reliability of the device. Furthermore, when a light source having a plurality of LEDs arranged in an array is used to project a light emission pattern onto a projection surface, the appearance of the light emission pattern is also important.

[0005] Therefore, an object of the present invention is to provide a lighting device or the like that can suppress deterioration in the appearance of the light-emitting pattern and can improve thermal reliability.

[0006] An illumination device according to one aspect of the present invention includes a light source having a plurality of light-emitting elements arranged in an array; a projection lens that projects light emitted by the light source; an acquisition unit that acquires input data regarding the light emission pattern of the plurality of light-emitting elements; a control unit that individually controls the current supplied to each of the plurality of light-emitting elements based on the input data acquired by the acquisition unit; and a detection unit that detects the temperature of the light source, wherein the control unit determines whether the temperature of the light source satisfies a predetermined condition based on the temperature of the light source detected by the detection unit, and if it is determined that the temperature of the light source satisfies the predetermined condition, selects a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements based on the characteristics of the input data acquired by the acquisition unit, and adjusts the amount of current supplied to each of the plurality of light-emitting elements based on the selected current adjustment algorithm.

[0007] Furthermore, a control method according to one aspect of the present invention is a control method for a lighting device including a light source having a plurality of light-emitting elements arranged in an array, a projection lens that projects light emitted by the light source, and a detection unit that detects the temperature of the light source, the control method comprising the steps of: acquiring input data regarding the light emission pattern of the plurality of light-emitting elements; individually controlling the current supplied to each of the plurality of light-emitting elements based on the acquired input data; determining whether the temperature of the light source satisfies a predetermined condition based on the detected temperature of the light source; and, if it is determined that the temperature of the light source satisfies the predetermined condition, selecting a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements based on characteristics of the acquired input data; and adjusting the amount of current supplied to each of the plurality of light-emitting elements based on the selected current adjustment algorithm.

[0008] According to the present invention, it is possible to provide a lighting device or the like that can suppress deterioration in the appearance of the light-emitting pattern and improve thermal reliability.

[0009] FIG. 1 is a block diagram showing the configuration of an illumination device according to an embodiment. FIG. 2 is a schematic perspective view of an illumination device according to an embodiment. FIG. 3 is a flowchart showing the operation of an illumination device according to an embodiment. FIG. 4 is a diagram showing an example of a current adjustment algorithm selected when it is determined that the characteristics of input data are character information. FIG. 5 is a diagram showing an example of a change in the appearance of an illumination pattern when the amount of current is adjusted by the current adjustment algorithm shown in FIG. 4. FIG. 6 is a diagram showing an example of a current adjustment algorithm selected when it is determined that the characteristics of input data are graphic information. FIG. 7 is a diagram showing an example of a change in the appearance of an illumination pattern when the amount of current is adjusted by the current adjustment algorithm shown in FIG. 6. FIG. 8 is a diagram showing an example of a change in the appearance of an illumination pattern when the amount of current is adjusted by current adjustment algorithms that differ for each region. FIG. 9 is a diagram showing another example of a current adjustment algorithm. FIG. 10 is a diagram showing yet another example of a current adjustment algorithm.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component arrangements and connection forms, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components not recited in the independent claims will be described as optional components.

[0011] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0012] Furthermore, in this specification, terms indicating the relationship between elements, terms indicating the shape of elements, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0013] (Embodiment) [Configuration] First, the configuration of a lighting device according to this embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0014] Fig. 1 is a block diagram showing the configuration of a lighting device 100 according to the present embodiment. Fig. 2 is a schematic perspective view of the lighting device 100 according to the present embodiment.

[0015] 1, the lighting device 100 includes a light source 110, a projection lens 120, an acquisition unit 130, a control unit 140, a detection unit 150, a communication unit 160, and a storage unit 170. Furthermore, as shown in FIG. 2, the lighting device 100 includes a housing 180.

[0016] In the present embodiment, the lighting device 100 is, for example, a spotlight, and is attached to a wiring fixture (for example, a wiring duct or a ceiling hook) provided on a ceiling or a wall. The lighting device 100 may also be a downlight or a ceiling light.

[0017] The light source 110 has a plurality of light-emitting elements 111 arranged in an array. The light source 110 emits light when a current is supplied from the control unit 140. The control unit 140 controls the on / off and light emission intensity (in other words, brightness) of each of the plurality of light-emitting elements 111 independently from one another. This allows the plurality of light-emitting elements 111 to emit light in a light emission pattern indicated by input data, which will be described later. The light emission pattern may be a still image (i.e., a light emission pattern that is constant over time) or a moving image (i.e., a light emission pattern that changes over time).

[0018] Each of the plurality of light-emitting elements 111 is, for example, a μLED. A μLED is a minute LED with a size of 100 μm × 100 μm or less. The μLED emits light by a current supplied from the control unit 140. The μLED includes, for example, a blue LED and a yellow phosphor arranged on the light-emitting side of the blue LED. The yellow phosphor is excited by a portion of the blue light emitted by the blue LED, and emits yellow light. The μLED emits white light as a mixture of blue light and yellow light. Note that the color of the light emitted by the μLED is not particularly limited.

[0019] The plurality of light-emitting elements 111 are arranged in a two-dimensional array on a substrate. The substrate is a rigid substrate, but may be a flexible substrate. The substrate is provided with, for example, pattern wiring for supplying current from the control unit 140 to each of the plurality of light-emitting elements 111.

[0020] The plurality of light-emitting elements 111 are arranged, for example, in a planar region of a predetermined size on a substrate, with tens to hundreds of elements arranged in each row and column. The planar region in which the light-emitting elements 111 are arranged is, for example, a rectangular region with a side length of several millimeters. The number of light-emitting elements 111 and the size of the region in which they are arranged are not particularly limited. By arranging the plurality of light-emitting elements 111 in a small region, it is possible to reduce the size of the projection lens 120 or improve the light capture efficiency.

[0021] The projection lens 120 projects the light emitted by the light source 110 onto a projection surface such as a wall, floor, stage, or screen. This projects the light emission pattern of the multiple light-emitting elements 111 onto the projection surface. The projection lens 120 is composed of multiple lenses, but may also be composed of a single lens.

[0022] The acquisition unit 130 acquires input data related to the light emission patterns of the plurality of light-emitting elements 111. The acquisition unit 130 acquires, for example, input data transmitted from an external device via the communication unit 160. The acquisition unit 130 may acquire the input data stored in the storage unit 170. The acquisition unit 130 is realized, for example, by a microcontroller. The microcontroller includes, for example, a non-volatile memory in which a program is stored, a volatile memory that is a temporary storage area for executing the program, an input / output port, a processor that executes the program, and the like. The program may be stored in the storage unit 170. Alternatively, the acquisition unit 130 may be a dedicated processing circuit that performs the processing performed by the acquisition unit 130.

[0023] The control unit 140 is a processing circuit that controls the driving of the light source 110. Specifically, the control unit 140 individually controls the current supplied to each of the plurality of light-emitting elements 111 based on the input data acquired by the acquisition unit 130. This controls the on / off and emission intensity of each of the plurality of light-emitting elements 111 when they are on, and the emission pattern of the plurality of light-emitting elements 111 is projected by the projection lens 120. Furthermore, the control unit 140 adjusts the amount of current supplied to each of the plurality of light-emitting elements 111 based on the temperature of the light source 110 detected by the detection unit 150. Details of the control performed by the control unit 140 will be described later. In this specification, the amount of current indicates the amount of current per unit time, unless otherwise specified.

[0024] The control unit 140 supplies, for example, a current modulated by PWM (Pulse Width Modulation) to each of the plurality of light-emitting elements 111. By adjusting the pulse width of the current to be supplied (i.e., adjusting the duty ratio) for each light-emitting element 111 and adjusting the amount of current to be supplied, it is possible to change the light emission intensity of each light-emitting element 111 and realize a dimming function. Note that the dimming method is not particularly limited, and may be an amplitude modulation method, a phase modulation method, or the like.

[0025] The control unit 140 is realized by, for example, an ASIC (Application Specific Integrated Circuit) and a microcontroller. The microcontroller includes, for example, a non-volatile memory in which a program is stored, a volatile memory that is a temporary storage area for executing the program, an input / output port, a processor that executes the program, and the like. The program may be stored in the storage unit 170. The microcontroller that realizes the acquisition unit 130 and the microcontroller that realizes the control unit 140 may be the same or different. Furthermore, the control unit 140 may be a dedicated processing circuit that performs the processing performed by the control unit 140.

[0026] The detection unit 150 detects the temperature of the light source 110. The detection unit 150 detects the temperature of a location in the light source 110 where the plurality of light emitting elements 111 are formed. The detection unit 150 may detect the temperature of one location in the light source 110, or may detect the temperature of a plurality of locations in each of the plurality of regions when the light source 110 is divided into a plurality of regions. The detection unit 150 is configured with one or more temperature sensors. The temperature sensor is, for example, a thermistor, but is not particularly limited to this.

[0027] The communication unit 160 communicates with an external device to acquire input data related to the light emission patterns of the plurality of light-emitting elements 111. The communication unit 160 is realized by a communication interface (communication circuit) for communicating with the external device via a network or the like. The communication may be wireless or wired. There are no particular limitations on the communication standard.

[0028] The storage unit 170 stores information and data necessary for the processing performed by the control unit 140. The storage unit 170 is, for example, a non-volatile storage device such as a hard disk drive (HDD) or a flash memory.

[0029] The housing 180 houses the light source 110, the projection lens 120, the acquisition unit 130, the control unit 140, the detection unit 150, the communication unit 160, and the storage unit 170. The housing 180 includes, for example, a plurality of components such as an outer shell housing that forms the outer shell of the lighting device 100 and a heat sink, but is not particularly limited to these. The components that make up the housing 180 are formed using resin or metal. Note that at least one of the acquisition unit 130, the control unit 140, the communication unit 160, and the storage unit 170 may be disposed outside the housing 180.

[0030] An opening is provided in the housing 180 on the light emission side of the light source 110 (in the normal direction of the main surface of the substrate), and the projection lens 120 is arranged to close the opening. Since there is no need to provide a liquid crystal device or a DMD (Digital Mirror Device) inside the housing 180, as in a general projector, the illumination device 100 can be made smaller.

[0031] [Operation] Next, the operation of the lighting device 100 according to the present embodiment will be described with reference to FIG.

[0032] FIG. 3 is a flowchart showing the operation of the lighting device 100 according to the present embodiment.

[0033] 3, first, the acquisition unit 130 acquires input data related to the light emission pattern of the plurality of light-emitting elements 111 (step S11). The input data includes pattern information indicating the light emission pattern of the plurality of light-emitting elements 111. The pattern information is, for example, information indicating the light emission intensity (brightness) of each of the plurality of light-emitting elements 111. The input data may further include tag information indicating that the light emission pattern is a character. When the light emission pattern is a moving image, the acquisition unit 130 continuously acquires the input data, and the pattern information changes over time.

[0034] Next, the control unit 140 supplies current to the light source 110 based on the input data acquired by the acquisition unit 130 (step S12). The control unit 140 controls the current supplied to each of the plurality of light-emitting elements 111 so that the light emission intensity of each of the plurality of light-emitting elements 111 is equal to the light emission intensity indicated by the pattern information. As a result, the light emitted by the light source 110 is projected onto the projection surface by the projection lens 120 in the form of an emission pattern of the plurality of light-emitting elements 111.

[0035] Next, the control unit 140 acquires the temperature of the light source 110 detected by the detection unit 150 (step S13). For example, the control unit 140 associates the temperature of the light source 110 detected by the detection unit 150 with time information and stores it in the storage unit 170. The control unit 140 may continue to acquire the temperature of the light source 110 detected by the detection unit 150 at predetermined intervals of several seconds to several tens of seconds for a predetermined period after the light source 110 starts to emit light.

[0036] Next, the control unit 140 determines whether the temperature of the light source 110 satisfies a predetermined condition based on the temperature of the light source 110 detected by the detection unit 150 (step S14). The predetermined condition is set to a temperature condition at which the light source 110 may be thermally deteriorated.

[0037] In step S14, the control unit 140 determines whether the temperature of the light source 110 detected by the detection unit 150 in step S13 exceeds a predetermined threshold, for example. At this time, the control unit 140 determines that the temperature of the light source 110 satisfies a predetermined condition when the temperature of the light source 110 detected by the detection unit 150 exceeds the predetermined threshold. This makes it possible to prevent the light source 110 from rising to a temperature at which it would be deteriorated by heat by adjusting the amount of current, which will be described later.

[0038] Furthermore, in step S14, the control unit 140 may predict whether the temperature of the light source 110 will exceed a predetermined threshold based on the temperature of the light source 110 detected by the detection unit 150 in step S13 and the change in the temperature of the light source 110 over time. In this case, if the control unit 140 predicts that the temperature of the light source 110 will exceed the predetermined threshold, it determines that the temperature of the light source 110 satisfies a predetermined condition. In the above prediction, the control unit 140 predicts the maximum temperature that would be reached if light emission were to continue under the current conditions, for example, based on the current temperature of the light source 110 and transient thermal characteristics such as the gradient of the temperature of the light source 110 over time for a predetermined period up to the present. The control unit 140 then determines whether the predicted maximum temperature exceeds the predetermined threshold. This makes it possible to further prevent the light source 110 from rising to a temperature that would cause thermal degradation by adjusting the amount of current, as described below.

[0039] The predetermined threshold value used in the above determination is set based on the heat resistance of the light emitting element 111, for example.

[0040] If the control unit 140 determines that the temperature of the light source 110 does not satisfy the predetermined condition (No in step S14), it supplies current to the light source 110 without adjusting the amount of current (step S15). That is, a current that achieves the light emission intensity of each of the plurality of light-emitting elements 111 indicated by the pattern information is supplied to each of the plurality of light-emitting elements 111. Therefore, if the amount of current to each of the plurality of light-emitting elements 111 has not been adjusted as described below at the time of determination, the amount of current supplied to each of the plurality of light-emitting elements 111 remains unchanged, and each of the plurality of light-emitting elements 111 maintains its current light emission intensity. Furthermore, if the amount of current to each of the plurality of light-emitting elements 111 has been adjusted as described below at the time of determination, the amount of current supplied to each of the plurality of light-emitting elements 111 returns to the amount of current before adjustment.

[0041] Then, after step S15, for example, several seconds to several tens of seconds after step S15, step S13 is performed again.

[0042] On the other hand, if the control unit 140 determines that the temperature of the light source 110 satisfies the predetermined condition (Yes in step S14), the control unit 140 determines the characteristics of the input data acquired by the acquisition unit 130 (step S16). The control unit 140 determines, for example, whether the characteristics of the input data are character information or graphic information. In other words, the characteristics of the input data are the object indicated by the light emission pattern.

[0043] Being textual information can also be considered a characteristic of input data when a light-emitting pattern functions as an information display. Therefore, being textual information can include cases where the light-emitting pattern has symbols for transmitting information. Also, being graphic information can be considered a characteristic of input data when the light-emitting pattern functions as illumination light or stage lighting. Therefore, being graphic information can include cases where the light-emitting pattern is a graphic shaped like a character, such as when the light-emitting pattern is a single, very large, bold character.

[0044] The control unit 140 determines the characteristics of the input data based on, for example, pattern information included in the input data acquired by the acquisition unit 130. This makes it possible to determine the characteristics of the input data even if the input data does not include information indicating the characteristics.

[0045] For example, the control unit 140 determines the characteristics of the input data based on a trained model that indicates the relationship between pattern information and the characteristics of the input data. This can improve the accuracy of determining the characteristics of the input data. The trained model is, for example, generated by performing machine learning on a model using training data in which the relationship between the pattern information and the characteristics of the input data is known in advance, and is stored in the storage unit 170. The trained model takes pattern information as input and outputs the characteristics of the input data. The input of the trained model may be a feature extracted from the pattern information by the control unit 140. Alternatively, the control unit 140 may determine the characteristics of the input data based on a database in which pattern information and the characteristics of the input data are associated. The database is stored in the storage unit 170. Alternatively, the control unit 140 may determine the characteristics of the input data based on the proportion of lit light-emitting elements 111 among the multiple light-emitting elements 111 in the pattern information.

[0046] Furthermore, the control unit 140 may determine the characteristics of the input data based on tag information included in the input data. For example, if the input data includes tag information indicating that the light emitting pattern is text, the control unit 140 determines that the characteristics of the input data are text information, and if the input data does not include the tag information, the control unit 140 determines that the characteristics of the input data are graphic information.

[0047] Next, based on the determined characteristics of the input data, the control unit 140 selects a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements 111 (step S17). Then, based on the selected current adjustment algorithm, the control unit 140 adjusts the amount of current supplied to each of the plurality of light-emitting elements 111 (step S18).

[0048] A plurality of current adjustment algorithms are stored in the storage unit 170, and the control unit 140 selects one current adjustment algorithm to be used for adjusting the amount of current from the plurality of current adjustment algorithms based on the determined characteristics of the input data. By applying the selected current adjustment algorithm to the adjustment of the amount of current, the amount of current supplied to at least some of the plurality of light-emitting elements 111 is adjusted so as to reduce the total amount of current supplied to the plurality of light-emitting elements 111 (i.e., the amount of current supplied to the light source 110 by the control unit 140). This makes it possible to reduce the amount of current supplied to the light source 110, thereby suppressing a temperature rise in the light source 110 and improving the thermal reliability of the light source 110.

[0049] When the detection unit 150 detects the temperatures of multiple locations on the light source 110, for example, the processes from step S16 to step S18 are performed on an area corresponding to a location where the temperature satisfies a predetermined condition on the light source 110. Furthermore, if there is even one location among the multiple locations where the temperature satisfies a predetermined condition, the processes from step S16 to step S18 may be performed on the entire light source 110.

[0050] Then, after step S18, step S13 is performed again. Note that when the processes of steps S16 to S18 are repeatedly performed, the processes of steps S16 to S18 from the second time onwards may be omitted. In other words, after step S18, steps S13 and S14 may be repeatedly performed while the amount of current supplied to the light-emitting element 111 is adjusted until the temperature of the light source 110 no longer satisfies the predetermined condition. The interval at which step S13 is performed is, for example, about several seconds to several tens of seconds.

[0051] [Specific Example of Input Data Characteristic Determination and Current Adjustment Algorithm] Next, a specific example of input data characteristic determination and current adjustment algorithm will be described.

[0052] For example, when the control unit 140 determines that the characteristics of the input data are character information, it selects, as the current adjustment algorithm, an algorithm in which the amount of current after adjustment gradually increases in a downwardly convex curve as the amount of current before adjustment increases, as shown in FIG. 4. The amount of current before adjustment for each of the multiple light-emitting elements 111 is the amount of current supplied to each light-emitting element 111 so as to achieve the light emission intensity of each of the multiple light-emitting elements 111 indicated by the pattern information. FIG. 4 is a diagram showing an example of a current adjustment algorithm selected when it is determined that the characteristics of the input data are character information. FIG. 5 is a diagram showing an example of a change in the appearance of the light-emitting pattern when the amount of current is adjusted by the current adjustment algorithm shown in FIG. 4.

[0053] In Fig. 4 , the horizontal axis represents the amount of current supplied to each light-emitting element 111 before adjustment, and the vertical axis represents the amount of current supplied to each light-emitting element 111 after adjustment. Also, in Fig. 4 , the relationship between the amount of current before adjustment and the amount of current after adjustment when the amount of current is adjusted by a current adjustment algorithm is shown by a solid line. In other words, by applying the current adjustment algorithm, the amount of current supplied to each light-emitting element 111 is set to the amount of current after adjustment according to the correspondence shown by the solid line in Fig. 4 , depending on the amount of current before adjustment. Also, in Fig. 4 , the relationship between the amount of current before adjustment and the amount of current after adjustment when no adjustment of the amount of current is performed (i.e., when the amount of current is the same before and after adjustment) is shown by a dashed line. This also applies to Figs. 6 , 9 , and 10 , which show other current adjustment algorithms to be described later.

[0054] 4 , the current amount does not change before and after the current amount adjustment for the light-emitting element 111 to which the amount of current supplied before adjustment is 0 and the light-emitting element 111 to which the amount of current supplied before adjustment is the maximum current amount Imax. That is, the luminance of the light-emitting element 111 emitting light at the maximum luminance and the light-emitting element 111 emitting light at the minimum luminance (in other words, turned off) does not change. Here, the maximum current amount Imax may be the maximum amount of current that can be supplied to the light-emitting element 111, or may be the maximum amount of current among the amounts of current supplied to each of the multiple light-emitting elements 111 before the current amount adjustment.

[0055] On the other hand, for light emitting elements 111 to which the amount of current supplied before adjustment is greater than 0 and smaller than the maximum current amount Imax, the amount of current after adjustment becomes smaller than the amount of current before adjustment. In other words, the brightness of light emitting elements 111 emitting light at intermediate gradations decreases. By adjusting the amount of current using such a current adjustment algorithm, the control unit 140 can reduce the amount of current supplied to the light source 110.

[0056] As a result of adjusting the amount of current supplied to each light-emitting element 111 using the current adjustment algorithm shown in FIG. 4 , as shown in FIG. 5 , the appearance of the light-emitting pattern of the multiple light-emitting elements 111 before and after the current adjustment is such that maximum brightness is maintained, but the shape is not maintained and becomes thinner. When the input data has character information characteristics, it is important that the characters can be visually recognized (that the message indicated by the characters is conveyed). Therefore, by maintaining the maximum brightness of the light-emitting pattern, it is possible to prevent the characters from becoming difficult to recognize, thereby preventing a deterioration in the appearance of the light-emitting pattern. Furthermore, by adjusting the amount of current to reduce the amount of current supplied to the light-emitting elements 111 that emit light at intermediate gradations, it is possible to prevent a temperature rise in the light source 110.

[0057] In the example shown in Figure 4, in the light-emitting element 111 where the amount of current supplied before adjustment is the maximum current amount Imax, the amount of current did not change before and after the adjustment of the current amount, but the amount of current after adjustment may be smaller than the maximum current amount Imax as long as it does not affect the appearance of the light-emitting pattern.

[0058] Furthermore, when the control unit 140 determines that the characteristics of the input data are graphic information, for example, it selects, as the current adjustment algorithm, an algorithm in which the amount of current after adjustment gradually increases in an upwardly convex curve as the amount of current before adjustment increases, as shown in Fig. 6. Fig. 6 is a diagram showing an example of a current adjustment algorithm selected when it is determined that the characteristics of the input data are graphic information. Fig. 7 is a diagram showing an example of a change in the appearance of the light emission pattern when the amount of current is adjusted by the current adjustment algorithm shown in Fig. 6.

[0059] 6, in the light-emitting element 111 to which the amount of current supplied before adjustment is 0, the amount of current does not change before and after the adjustment of the amount of current. In other words, the luminance of the light-emitting element 111 emitting light at the minimum luminance (in other words, turned off) does not change.

[0060] On the other hand, for light-emitting elements 111 to which the amount of current supplied before adjustment is greater than 0, the greater the amount of current before adjustment, the smaller the amount of current after adjustment relative to the amount of current before adjustment. Therefore, the lower the brightness of a light-emitting element 111, the less likely its brightness is to decrease. Furthermore, for light-emitting elements 111 to which the amount of current supplied before adjustment is the maximum current amount Imax, the amount of current after adjustment becomes a current amount Ia that is smaller than the maximum current amount Imax. Therefore, the brightness of light-emitting elements 111 emitting light at high gradations decreases. By adjusting the amount of current using such a current adjustment algorithm, the amount of current supplied to the light source 110 can be reduced.

[0061] As a result of adjusting the amount of current supplied to the light-emitting elements 111 by the current adjustment algorithm shown in FIG. 6 , as shown in FIG. 7 , the shape of the light-emitting pattern of the multiple light-emitting elements 111 is maintained before and after the current adjustment, but the maximum brightness is not maintained and the pattern becomes darker. When the input data characteristic is graphic information, it is important that the shape of the graphic is displayed correctly. Therefore, by maintaining the shape of the light-emitting pattern, the shape of the graphic is displayed correctly, thereby suppressing deterioration in the appearance of the light-emitting pattern. Furthermore, by adjusting the amount of current, the amount of current supplied to the light-emitting elements 111 that emit light at high gradations can be reduced, thereby suppressing temperature increases in the light source 110.

[0062] In a current adjustment algorithm in which the amount of current after adjustment gradually increases in a curve that is convex upward as the amount of current before adjustment increases, for example, the amount of current after adjustment is adjusted so that it is equal to or less than the amount of current before adjustment in each light-emitting element 111. This makes it possible to effectively reduce the amount of current supplied to the light source 110. Note that in this current adjustment algorithm, the amount of current after adjustment may be greater than the amount of current before adjustment in some light-emitting elements 111, as long as the total amount of current supplied to the plurality of light-emitting elements 111 can be reduced by adjusting the amount of current.

[0063] In the above example, in step S16, the control unit 140 determines whether the characteristic of the input data is character information or graphic information, but the determination example is not limited to this. Depending on the light emission pattern that can be used, the characteristic of the input data determined by the control unit 140 can be appropriately set to a characteristic that corresponds to the purpose, such as communication, instruction, attention, lighting effect, or improved visibility.

[0064] Furthermore, for example, in step S16, the control unit 140 may determine whether the characteristics of the input data are character information or graphic information, as well as whether character information and graphic information are mixed. If the control unit 140 determines that the characteristics of the input data are a mixture of character information and graphic information, it divides the planar region in which the light emitting elements 111 are arranged in the light source 110 into a region in which the light emitting elements 111 corresponding to the character information are present and a region in which the light emitting elements 111 corresponding to the graphic information are present. Then, the control unit 140 selects a different current adjustment algorithm for each divided region and adjusts the amount of current supplied to each of the plurality of light emitting elements 111 based on the current adjustment algorithm selected for each divided region.

[0065] FIG. 8 illustrates an example of how the appearance of a light-emitting pattern changes when the amount of current is adjusted using different current adjustment algorithms for each region. The example illustrated in FIG. 8 illustrates a light-emitting pattern when the planar region in which the light-emitting elements 111 are arranged in the light source 110 is divided into region A1, where the light-emitting elements 111 corresponding to text information are located, and region A2, where the light-emitting elements 111 corresponding to graphic information are located. The control unit 140 adjusts the amount of current by selecting the current adjustment algorithm shown in FIG. 4 for region A1, and by selecting the current adjustment algorithm shown in FIG. 6 for region A2. This maintains the maximum brightness of the light-emitting pattern in region A1, while maintaining the shape of the light-emitting pattern in region A2. Therefore, the amount of current is adjusted for each region A1 and A2 according to the characteristics of the input data, thereby suppressing degradation in the appearance of the light-emitting pattern. In this way, when the input data contains a mixture of different characteristics, the control unit 140 divides the light source 110 into regions corresponding to the characteristics and selects different current adjustment algorithms for each divided region, thereby more effectively suppressing degradation in the appearance of the light-emitting pattern.

[0066] [Summary] As described above, the lighting device 100 according to this embodiment includes the light source 110 having the plurality of light-emitting elements 111 arranged in an array, the projection lens 120 that projects the light emitted by the light source 110, the acquisition unit 130 that acquires input data related to the light emission pattern of the plurality of light-emitting elements 111, the control unit 140 that individually controls the current supplied to each of the plurality of light-emitting elements 111 based on the input data acquired by the acquisition unit 130, and the detection unit 150 that detects the temperature of the light source 110. The control unit 140 determines whether the temperature of the light source 110 satisfies a predetermined condition based on the temperature of the light source 110 detected by the detection unit 150, and if it is determined that the temperature of the light source 110 satisfies the predetermined condition, selects a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements 111 based on characteristics of the input data acquired by the acquisition unit 130, and adjusts the amount of current supplied to each of the plurality of light-emitting elements 111 based on the selected current adjustment algorithm.

[0067] This allows the amount of current supplied to each of the plurality of light-emitting elements 111 to be adjusted according to the temperature of the light source 110, thereby suppressing a temperature rise in the light source 110 and reducing the thermal load on the light source 110. Furthermore, the amount of current supplied to each of the plurality of light-emitting elements 111 is adjusted according to a current adjustment algorithm selected based on the characteristics of the input data, thereby enabling adjustment of the amount of current according to the characteristics of the input data. For example, as described above, it is possible to select a current adjustment algorithm that has little effect on the appearance of the light-emitting pattern depending on whether the characteristics of the input data are text information or graphic information. Therefore, the lighting device 100 can suppress deterioration in the appearance of the light-emitting pattern and improve thermal reliability.

[0068] (Others) Although the lighting device and the lighting device control method according to the present invention have been described based on the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment.

[0069] For example, in the above embodiment, the light-emitting element 111 is a μLED, but this is not limiting. The light-emitting element 111 may be an LED that is larger than a μLED, such as a general-sized LED. Furthermore, the light-emitting element 111 may be an organic EL element or a laser element.

[0070] Furthermore, for example, the current adjustment algorithm is not limited to the examples shown in FIGS. 4 and 6 described above, and an algorithm that reduces the total amount of current supplied to multiple light-emitting elements 111 may be used as appropriate. FIG. 9 is a diagram illustrating another example of a current adjustment algorithm. FIG. 10 is a diagram illustrating yet another example of a current adjustment algorithm. In the current adjustment algorithm shown in FIG. 9 , when the amount of current before adjustment is equal to or less than a predetermined amount, the amount of current after adjustment increases linearly as the amount of current before adjustment increases, and becomes constant at a predetermined current Ib that is smaller than the maximum current Imax. In other words, the amount of current supplied to each light-emitting element 111 peaks out at the predetermined current Ib. In addition, in the current adjustment algorithm shown in FIG. 10 , the amount of current after adjustment increases linearly as the amount of current before adjustment increases, with a smaller slope than when the current amount is not adjusted. In other words, the amount of current supplied to each light-emitting element 111 is reduced by a predetermined percentage.

[0071] In the above-described embodiment, the processing performed by a specific processing unit may be performed by another processing unit, the order of multiple processing operations may be changed, or multiple processing operations may be performed in parallel.

[0072] For example, the processes described in the above embodiments may be realized by centralized processing using a single processing circuit or device, or by distributed processing using multiple processing circuits or devices. Furthermore, the processor that executes the program may be a single processor or multiple processors. That is, centralized processing or distributed processing may be performed.

[0073] In the above-described embodiments, all or some of the components such as the control unit may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU (Central Processing Unit) or a processor reading and executing a software program recorded on a recording medium such as an HDD (Hard Disk Drive) or semiconductor memory.

[0074] Furthermore, the components such as the control unit may be configured with one or more electronic circuits, each of which may be a general-purpose circuit or a dedicated circuit.

[0075] The one or more electronic circuits may include, for example, a semiconductor device, an IC, or an LSI. The IC or LSI may be integrated on a single chip or on multiple chips. Although the IC or LSI is referred to here as an IC or LSI, the name may vary depending on the degree of integration, and may be called a system LSI, a VLSI (Very Large Scale Integration), or an ULSI (Ultra Large Scale Integration). An FPGA, which is programmed after the LSI is manufactured, can also be used for the same purpose.

[0076] Furthermore, the general or specific aspects of the present invention may be realized as a system, an apparatus, a method, an integrated circuit, or a computer program. Alternatively, the present invention may be realized as a computer-readable non-transitory recording medium such as an optical disk, a HDD, or a semiconductor memory on which the computer program is stored. Alternatively, the present invention may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0077] In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the present invention.

[0078] Examples of the lighting device and control method according to the present invention that have been described based on the above embodiment will be shown below, but the lighting device and control method according to the present invention are not limited to the following examples.

[0079] A lighting device according to a first aspect of the present invention includes a light source having a plurality of light-emitting elements arranged in an array; a projection lens that projects light emitted by the light source; an acquisition unit that acquires input data regarding the light emission pattern of the plurality of light-emitting elements; a control unit that individually controls the current supplied to each of the plurality of light-emitting elements based on the input data acquired by the acquisition unit; and a detection unit that detects the temperature of the light source, wherein the control unit determines whether the temperature of the light source satisfies a predetermined condition based on the temperature of the light source detected by the detection unit, and if it is determined that the temperature of the light source satisfies the predetermined condition, selects a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements based on characteristics of the input data acquired by the acquisition unit, and adjusts the amount of current supplied to each of the plurality of light-emitting elements based on the selected current adjustment algorithm.

[0080] A lighting device according to a second aspect of the present invention is the lighting device according to the first aspect, wherein, when the control unit determines that the characteristics of the input data acquired by the acquisition unit are character information in selecting the current adjustment algorithm, the control unit selects, as the current adjustment algorithm, an algorithm in which the amount of current after adjustment gradually increases in a downwardly convex curve as the amount of current before adjustment increases.

[0081] A lighting device according to a third aspect of the present invention is the lighting device according to the first or second aspect, wherein, when the control unit determines that the characteristics of the input data acquired by the acquisition unit are graphic information in selecting the current adjustment algorithm, the control unit selects, as the current adjustment algorithm, an algorithm in which the amount of current after adjustment gradually increases in an upwardly convex curve as the amount of current before adjustment increases.

[0082] A lighting device according to a fourth aspect of the present invention is the lighting device according to any one of the first to third aspects, wherein, in selecting the current adjustment algorithm, the control unit determines characteristics of the input data based on pattern information indicating the light emission pattern included in the input data acquired by the acquisition unit, and selects the current adjustment algorithm based on the determined characteristics of the input data.

[0083] A lighting device according to a fifth aspect of the present invention is the lighting device according to any one of the first to fourth aspects, wherein, in selecting the current adjustment algorithm, the control unit determines characteristics of the input data acquired by the acquisition unit based on a trained model that indicates a relationship between pattern information indicating the light emission pattern included in the input data and characteristics of the input data, and selects the current adjustment algorithm based on the determined characteristics of the input data.

[0084] A lighting device according to a sixth aspect of the present invention is the lighting device according to any one of the first to fifth aspects, wherein the control unit, in determining whether the temperature of the light source satisfies the predetermined condition, determines that the temperature of the light source satisfies the predetermined condition if the temperature of the light source detected by the detection unit exceeds a predetermined threshold.

[0085] A lighting device according to a seventh aspect of the present invention is the lighting device according to any one of the first to fifth aspects, wherein, in determining whether the temperature of the light source satisfies the predetermined condition, the control unit predicts whether the temperature of the light source will exceed a predetermined threshold based on the temperature of the light source detected by the detection unit and a change in the temperature of the light source over time, and determines that the temperature of the light source satisfies the predetermined condition if it predicts that the temperature of the light source will exceed the predetermined threshold.

[0086] An illumination device according to an eighth aspect of the present invention is the illumination device according to any one of the first to seventh aspects, wherein, when the control unit determines, in selecting the current adjustment algorithm, that the characteristics of the input data acquired by the acquisition unit are a mixture of character information and graphic information, the control unit divides the light source into an area where light-emitting elements corresponding to the character information exist and an area where light-emitting elements corresponding to the graphic information exist, and selects a current adjustment algorithm that differs from each other for each divided area.

[0087] A control method according to a ninth aspect of the present invention is a control method for a lighting device comprising a light source having a plurality of light-emitting elements arranged in an array, a projection lens that projects light emitted by the light source, and a detection unit that detects the temperature of the light source, the control method comprising the steps of: acquiring input data regarding the light emission pattern of the plurality of light-emitting elements; individually controlling the current supplied to each of the plurality of light-emitting elements based on the acquired input data; determining whether the temperature of the light source satisfies a predetermined condition based on the detected temperature of the light source; and, if it is determined that the temperature of the light source satisfies the predetermined condition, selecting a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements based on characteristics of the acquired input data; and adjusting the amount of current supplied to each of the plurality of light-emitting elements based on the selected current adjustment algorithm.

[0088] REFERENCE SIGNS LIST 100 Illumination device 110 Light source 111 Light-emitting element 120 Projection lens 130 Acquisition unit 140 Control unit 150 Detection unit

Claims

1. A lighting device comprising: a light source having a plurality of light-emitting elements arranged in an array; a projection lens which projects light emitted by the light source; an acquisition unit which acquires input data relating to the emission pattern of the plurality of light-emitting elements; a control unit which individually controls a current supplied to each of the plurality of light-emitting elements based on the input data acquired by the acquisition unit; and a detection unit which detects a temperature of the light source, wherein the control unit determines whether the temperature of the light source satisfies a predetermined condition based on the temperature of the light source detected by the detection unit, and if it is determined that the temperature of the light source satisfies the predetermined condition, selects a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements based on characteristics of the input data acquired by the acquisition unit, and adjusts the amount of current supplied to each of the plurality of light-emitting elements based on the selected current adjustment algorithm.

2. The lighting device according to claim 1, wherein, when the control unit determines that the characteristics of the input data acquired by the acquisition unit are character information, in selecting the current adjustment algorithm, the control unit selects as the current adjustment algorithm an algorithm in which the amount of current after adjustment gradually increases in a downwardly convex curve as the amount of current before adjustment increases.

3. The lighting device of claim 1, wherein, when the control unit determines that the characteristics of the input data acquired by the acquisition unit are graphic information, in selecting the current adjustment algorithm, the control unit selects as the current adjustment algorithm an algorithm in which the amount of current after adjustment gradually increases in an upwardly convex curve as the amount of current before adjustment increases.

4. The lighting device of claim 1, wherein, in selecting the current adjustment algorithm, the control unit determines characteristics of the input data based on pattern information indicating the light emission pattern contained in the input data acquired by the acquisition unit, and selects the current adjustment algorithm based on the determined characteristics of the input data.

5. The lighting device described in claim 1, wherein, in selecting the current adjustment algorithm, the control unit determines characteristics of the input data acquired by the acquisition unit based on a trained model that indicates a relationship between pattern information indicating the light emission pattern included in the input data and characteristics of the input data, and selects the current adjustment algorithm based on the determined characteristics of the input data.

6. A lighting device as claimed in any one of claims 1 to 5, wherein, in determining whether the temperature of the light source satisfies the specified condition, the control unit determines that the temperature of the light source satisfies the specified condition if the temperature of the light source detected by the detection unit exceeds a specified threshold value.

7. A lighting device as claimed in any one of claims 1 to 5, wherein, in determining whether the temperature of the light source satisfies the specified condition, the control unit predicts whether the temperature of the light source will exceed a specified threshold based on the temperature of the light source detected by the detection unit and the change in the temperature of the light source over time, and determines that the temperature of the light source satisfies the specified condition when it predicts that the temperature of the light source will exceed the specified threshold.

8. A lighting device as claimed in any one of claims 1 to 5, wherein, when the control unit determines that the characteristics of the input data acquired by the acquisition unit are a mixture of character information and graphic information, in selecting the current adjustment algorithm, the control unit divides the light source into an area in which light-emitting elements corresponding to the character information exist and an area in which light-emitting elements corresponding to the graphic information exist, and selects a different current adjustment algorithm for each divided area.

9. A control method for a lighting device comprising a light source having a plurality of light-emitting elements arranged in an array, a projection lens that projects light emitted by the light source, and a detection unit that detects the temperature of the light source, comprising the steps of: acquiring input data relating to the light emission pattern of the plurality of light-emitting elements; individually controlling a current supplied to each of the plurality of light-emitting elements based on the acquired input data; determining whether or not the temperature of the light source satisfies a predetermined condition based on the detected temperature of the light source; if it is determined that the temperature of the light source satisfies the predetermined condition, selecting a current adjustment algorithm for adjusting the amount of current supplied to each of the plurality of light-emitting elements based on characteristics of the acquired input data; and adjusting the amount of current supplied to each of the plurality of light-emitting elements based on the selected current adjustment algorithm.

Images