Light source device, display device, and method for installing light source device

Abstract

A light source device, a display device, and a mounting method of a light source device, which can achieve ease of mounting of a temperature detecting portion and improvement of accuracy of temperature measurement in the light source device. The light source device has: a plurality of light sources provided on a light source mounting region (22) on a mounting surface (80) of a circuit board (50); at least one temperature detecting portion (32) provided on the mounting surface outside the light source mounting region; and a heat pattern (26) having a main portion (26a) that collects heat generated in association with light emission of at least one light source in an arbitrary position among the plurality of light sources and a connection portion (26c) that is thermally connected to the temperature detecting portion and transfers the heat from the main portion to the temperature detecting portion, the circuit board including a surface layer (50-4) on which the plurality of light sources are mounted and at least one inner layer (50-3) provided on a lower side of the surface layer via an electrically insulating film (70), the main portion of the heat pattern being provided on the inner layer in a manner of overlapping the light source mounting region and as viewed in plan from the upper side.

Description

Technical Field

[0001] This invention relates to a light source device, a display device, and a method for installing the light source device. Background Technology

[0002] Patent document 1 discloses a display device that implements a suppression process to suppress display changes caused by temperature variations in the display panel.

[0003] In this patent document 1 Figure 2 The diagram shows a structure in which a backlight temperature detection unit, which detects the temperature of the backlight located on the back of the LCD panel, is located in the center (center) of the backlight configuration area.

[0004] In addition, Patent Document 1 Figure 6 The diagram shows the system structure for implementing the above-mentioned suppression process in a display device that implements local dimming drive.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2014-149485 Summary of the Invention

[0006] The technical problem that the invention aims to solve Through the research of the inventors of this invention, the following issues have been identified.

[0007] (1) For example, when measuring the temperature of the backlight section (specifically, an LED substrate on which a light-emitting diode (LED) is mounted as a light source) in an in-vehicle display device, a surface-mount thermistor (generally a temperature sensing unit) is conventionally used to observe the temperature of the LED substrate after the LED is heated by the lit LED.

[0008] In the aforementioned patent document 1 Figure 2 In the described example of the light source device structure, a thermistor, which serves as a backlight temperature detection unit, is also disposed in the central part (center part) of the LED configuration area, which serves as the light source.

[0009] However, in recent years, the integration of light sources in LED substrates has been continuously developing, which sometimes makes it difficult to ensure space for placing thermistors in the center of the LED substrate.

[0010] (2) For example, in an LED substrate of a display device using a local dimming drive, the LED mounting area is divided into multiple areas, and a thermistor needs to be set for each of the divided areas. Therefore, it is difficult to ensure the space for configuring the thermistors.

[0011] Specifically, due to the narrowing of the mounting spacing between LEDs, it is not easy to ensure the mounting area of ​​the thermistor in each segmented region.

[0012] In addition, sometimes light boxes (including reflectors, etc.) are arranged in a way that surrounds each LED in the LED mounting area. In this case, it becomes more difficult to ensure the space for the thermistor.

[0013] (3) In addition, when using a local dimming drive, it is possible to individually light up an LED at any position corresponding to the displayed image. In other words, the position of the LED, which is a heat source, changes according to the displayed image, and a local increase in heat generation caused by the LED will also occur in a part of the LED substrate.

[0014] Therefore, for example, it is difficult to observe the accurate temperature rise of the entire LED substrate using a single thermistor.

[0015] In other words, when using a local dimming drive method, LEDs at arbitrary locations are lit in conjunction with the displayed image. Therefore, if the lighting rate of LEDs far from the thermistor is concentrated, heat cannot be fully transferred to the thermistor. As a result, the thermistor will measure a temperature lower than the actual LED substrate temperature. Based on this large error measurement result, the LED temperature is estimated and heat-reducing measures are implemented. It is undeniable that the timing of the implementation of heat-reducing measures may be delayed, or the accuracy of the heat-reducing measures may be reduced.

[0016] (4) As a countermeasure to the problem mentioned in (3) above, for example, there is a consideration of placing the thermistor on the back of the LED substrate. However, in this case, the thermistor will come into contact with the heat sink located directly below the LED substrate. Since the heat is dissipated through the heat sink, it is difficult to measure the accurate temperature rise of the LED substrate.

[0017] (5) In addition, as another countermeasure, it is also considered to place thermistors at the four corners of the LED installation area (the LED installation area is assumed to be a rectangular installation area here), and calculate the parameters obtained by averaging the four points based on the detection results of a total of four thermistors, or calculate the parameters obtained by multiplying each measured value by a correction factor, so as to implement LED heat generation control, etc.

[0018] However, in this case, with only the LEDs arranged in the center of the LED configuration area emitting light and generating heat, these LEDs are at the farthest distance from any of the thermistors set in the four corners, thus creating the problem of difficulty in accurately measuring the temperature rise.

[0019] (6) As mentioned above, it is not easy to place the thermistor in the LED configuration area. In addition, as a countermeasure, if the thermistor is installed in a position far away from the LED (for example, if multiple thermistors are arranged outside the LED configuration area), if only the LEDs located far away from each thermistor are lit, even if the temperature of the lit part has reached the temperature that needs to be controlled, the thermistor may observe a lower temperature, which will make it difficult to perform proper temperature control.

[0020] The present invention is based on the above research results, and one of its objectives is to provide a light source device, a display device, and a method for installing the light source device, which can facilitate the installation of the temperature detection unit and improve the accuracy of temperature measurement in the light source device.

[0021] Another object of the present invention will be apparent to those skilled in the art from the following illustrated schemes and preferred embodiments, as well as the accompanying drawings.

[0022] Technical solutions adopted to solve technical problems The following examples illustrate the solutions of the present invention in order to facilitate understanding of the invention.

[0023] In the first embodiment, the light source device includes: a plurality of light sources disposed on a mounting surface of a circuit board in a light source mounting area; at least one temperature detection unit disposed on the mounting surface outside the light source mounting area; and a thermal pattern having a main portion and a connecting portion, the main portion collecting heat generated by the emission of at least one of the plurality of light sources at any position, the connecting portion being thermally connected to the temperature detection unit and transferring heat from the main portion to the temperature detection unit. When the direction perpendicular to the mounting surface of the circuit board is defined as the vertical direction, the direction on the mounting surface side is defined as the upward direction, and the direction opposite to the upward direction is defined as the downward direction, the circuit board includes a surface layer on which the plurality of light sources are mounted, and at least one inner layer disposed below the surface layer separated by an electrically insulating film. The main portion of the thermal pattern, when viewed from above, overlaps with the light source mounting area and is disposed in the inner layer.

[0024] According to the first scheme, a thermal pattern (also known as thermal wiring) for transferring temperature is provided in the inner layer of the circuit board.

[0025] For example, copper (or an alloy with nickel, iron, etc.) with excellent thermal conductivity can be used as the heat pattern.

[0026] Alternatively, for example, the main part of the thermal pattern can be positioned directly below each light source (e.g., each LED) (in this case, when viewed from above, at least a portion of the thermal pattern overlaps with the light source (LED, etc.).

[0027] Therefore, even if the temperature detection unit is located separately from the light source (such as an LED) that serves as a heat source, the heat generated from the light source (such as an LED) can be effectively collected through the electrical insulation layer via the thermal pattern and effectively (in other words, with reduced heat loss) transferred to the temperature detection unit.

[0028] Therefore, even if the temperature detection unit is located outside the light source mounting area, the temperature of the circuit board (mounting board) can be measured (detected) with good accuracy.

[0029] Therefore, in the light source device, it is possible to simplify the installation of the temperature detection unit and improve the accuracy of temperature measurement.

[0030] In the second embodiment, which is subordinate to the first embodiment, the main portion of the thermal pattern may have a planar shape when viewed from above, and the planar shape of the main portion of the thermal pattern may overlap with each of the plurality of light sources. Alternatively, when viewed from above, the main portion of the thermal pattern may have multiple branch wires extending from the connecting portion, and each of the multiple branch wires may overlap with a portion or all of the first light source located above the branch wires in relative position to the first light source among the plurality of light sources. For the second light source among the plurality of light sources that is not located above the branch wires and does not overlap with the branch wires, the configuration may be such that each of the second light sources has the same shortest distance from the branch wires, or that the shortest distance falls within a predetermined allowable range.

[0031] In the second scheme, the main part of the thermal pattern is planar (solid pattern), which sometimes overlaps with the light sources located above it. Additionally, it has multiple branch wires (also called branch lines or branch patterns) extending from the connecting portion. When the light source located above each branch wire is designated as the first light source, part or all of each branch wire overlaps with the first light source configured corresponding to each branch wire. Therefore, effective heat collection is achieved for the first light source.

[0032] In addition, when a light source that is not located above each branch wiring and does not overlap with the branch wiring is designated as a second light source, it is configured such that each of the second light sources has the same shortest distance as the branch wiring, or such that the shortest distance falls within a predetermined allowable range.

[0033] In other words, for the aforementioned "second light source," the deviation of the shortest distance between each light source and the branch wiring of the thermal pattern when viewed from above falls within a predetermined allowable range.

[0034] Therefore, deviations in heat collection when collecting heat generated from each light source in the branch wiring can be suppressed (e.g., minimized). Thus, even if each light source is assumed to emit light and generate heat independently, the heat from that light source can be transferred to the temperature detection unit with good (in other words, accurately) precision.

[0035] For example, even if a portion of the light source in any location within the light source mounting area emits light locally, regardless of the relative position of this portion of the area to the light source mounting area (in other words, regardless of where this portion of the area is located within the light source mounting area), the temperature rise of the circuit board (mounting board) caused by this localized heating can be detected with high precision (accuracy).

[0036] According to this solution, regardless of the location of the light source, the temperature rise of the circuit board caused by the heat generated by the light source can be detected with high precision. Therefore, high-precision countermeasures to suppress the temperature rise can be implemented at the appropriate time.

[0037] In the third embodiment, which is subordinate to the second embodiment, if the main part of the thermal pattern has the multiple branch wires, each of the multiple branch wires may have a straight or curved shape when viewed from above.

[0038] In this scheme, the branch wiring, which is the main part of the thermal pattern, can be straight or curved.

[0039] Although light sources (such as LEDs) are arranged on the mounting surface of the circuit board, no light sources are arranged in the inner layer of the circuit board, leaving more free space and thus a higher degree of freedom in arranging thermal patterns. Therefore, the mounting state of the light sources can be considered, such as the shape of the light source mounting area, the arrangement of the light sources, the arrangement density of the light sources, and the configuration of the signal lines supplying signals to the light sources or the grounding (both of which are surface patterns), to select the shape of the pattern with high heat collection or heat transfer properties.

[0040] Therefore, the shape of the thermal pattern when viewed from above (specifically, the width and length of straight lines, the curvature, width, and length of curves, etc.) can be determined relatively freely.

[0041] In the fourth embodiment, which is subordinate to the first or second embodiment, the light source mounting area may have a rectangular shape when viewed from above. The plurality of light sources are arranged in a matrix in the light source mounting area. The plurality of light sources arranged in the matrix can be represented by a matrix of m rows and n columns (m is an integer greater than 4 and n is an integer greater than 2). In the matrix, when viewed from above, the straight branch wiring overlaps only with each of the light sources arranged in the matrix corresponding to rows where m is a multiple of 2.

[0042] In the fourth scheme, the arrangement of each light source is represented as an m-row n-column matrix (m is an integer greater than 4 and n is an integer greater than 2), and the linear branch wiring is configured such that all or part (preferably all) of each branch wiring, which is the main part of the thermal pattern, overlaps only with the light source of the matrix corresponding to a row that is a multiple of 2 (e.g., the matrix in the second row and first column when m is 2).

[0043] In this case, the light source corresponding to the matrix of rows where m is a multiple of 2 is equivalent to the "first light source" in the third scheme described above. Directly below the light source corresponding to the matrix of the 2nd and 4th rows (the same applies below), there are branch wirings that serve as the main part of the thermal pattern. For these light sources, since the heat generated by each light source is transferred to the main part of the thermal pattern via the electrically insulating film with the shortest distance, effective heat collection is achieved.

[0044] On the other hand, the light sources corresponding to the matrices in rows 1, 3, and 5 (hereinafter the same) are equivalent to the "second light source" in the third scheme described above. From a top-down view, since the light sources are regularly arranged, the shortest distance between each light source and the nearby branch wiring is, for example, the same (equal distance), and each light source is equally arranged near the branch wiring. Therefore, there is no deviation in the heat collection of each light source, and effective heat collection can be achieved for any light source.

[0045] Additionally, due to certain circumstances (e.g., layout reasons with other wiring (ground or signal lines)), the aforementioned minimum distances may sometimes vary. However, as long as the deviations of each minimum distance fall within a predetermined allowable range, deviations in heat collection performance when branch wiring of a thermal pattern collects heat generated from each light source can be suppressed (e.g., minimized).

[0046] Furthermore, although the distance between each light source and the temperature detection unit may vary depending on the position of each light source, the deviation in the length of the thermal pattern branch wiring can be ignored because the thermal pattern is made of a material with high thermal conductivity.

[0047] Therefore, according to this solution, the temperature rise of the circuit board (or each light source) caused by the heat generated by the light source can be detected with high precision (accurately) regardless of the location of the light source. Thus, a high-precision countermeasure can be implemented at the appropriate time to suppress the temperature rise.

[0048] In the fifth scheme, which is subordinate to any of the first to fourth schemes, the light source mounting area may be divided into multiple rectangular segments in a manner corresponding to the local dimming drive of the plurality of light sources. The temperature detection unit is disposed on the outside of a predetermined end of each segment in each segment, and the end of the connection portion in at least one of the thermal patterns on the side of the temperature detection unit is thermally connected to the temperature detection unit.

[0049] In the fifth embodiment, the present invention is applicable to the light source device of a display device employing a local dimming driving method.

[0050] As described above, in the prior art, when a local dimming driving method is used, the light source at any position is lit in conjunction with the displayed image. Therefore, when the position of the light source is far away from the temperature detection unit, the heat cannot be fully transferred to the temperature detection unit, resulting in a delay in the timing of implementing heat-relief measures. In addition, it is conceivable that the accuracy of heat-relief measures processing will decrease.

[0051] This solution can address the aforementioned issues.

[0052] Furthermore, in this solution, since heat can be effectively transferred to the temperature detection unit via a thermally conductive pattern, the temperature detection unit can be positioned outside a predetermined end of the light source mounting area, and the layout related to the configuration of the temperature detection unit becomes easier.

[0053] Furthermore, the predetermined end (or predetermined boundary line) can specifically be one of the four sides of the rectangle (quadrilateral), or the vicinity of that side, as the predetermined end (or predetermined boundary line).

[0054] In the sixth scheme, which is subordinate to any of the first to fifth schemes, the grounding of each of the plurality of light sources may include a ground plane with a wide wiring width and ground wires branching from the ground plane with a width narrower than the ground plane. The ground plane is not located around the main part of the thermal pattern, but is located in the light source mounting area away from the main part of the thermal pattern, or is located outside the light source mounting area.

[0055] In the sixth scheme, the ground plane (planar ground busbar) is not set around (near the main part of the thermal pattern), but is set in an empty area away from the thermal pattern (the main part of the thermal pattern) within the light source mounting area, or is set outside the light source mounting area.

[0056] This prevents heat emitted by the light source from escaping to the wider ground plane. Because the heat from the light source is efficiently transferred to the main part of the thermal pattern instead of escaping to the ground plane, there is no decrease in heat collection efficiency caused by the main part of the thermal pattern, thus maintaining high heat collection efficiency at all times.

[0057] In the seventh embodiment, which belongs to any of the first to sixth embodiments, the cathode electrode of the LED, which serves as the light source, may be disposed on the underside of each light source as a surface pattern disposed on the surface layer.

[0058] In the seventh embodiment, a cathode electrode of an LED (broadly defined as a light-emitting element or light source element) that serves as a surface pattern is provided below each light source mounted on the mounting surface.

[0059] The cathode electrode also functions as a heat dissipation component, transferring heat emitted by each light source to the main part of the thermal pattern positioned directly below it. This improves the heat collection efficiency of the main part of the thermal pattern.

[0060] In the eighth scheme, which belongs to any of the second to seventh schemes, the thickness of the branch wiring, which is the main part of the thermal pattern, can be set to be thinner than the width of each of the plurality of light sources in the direction corresponding to the thickness of the branch wiring when viewed from above.

[0061] In the eighth scheme, the width of the branch wiring, which is the main part of the thermal pattern, is set to be narrower than the width of each light source (light source device) in that width direction.

[0062] In recent years, the integration of various light sources has continued to advance, and the spacing between light sources has tended to become narrower. In addition, wiring or through-holes (or contact electrodes) used for connection to ground planes or signal lines can be placed in any position in the inner plane of the circuit board.

[0063] Even under these circumstances, according to this solution, since the width of the branch wiring, which is the main part of the thermal pattern, is set to be narrower than the width of each light source (each light source device), the area occupied by the thermal pattern becomes smaller. As a result, the branch wiring can be configured relatively freely to accommodate narrower spacing of each light source or a decrease in the degree of freedom of branch wiring configuration in the inner layer of the circuit board.

[0064] In the ninth embodiment, which belongs to any of the first to eighth embodiments, a light source control unit for controlling the driving of the plurality of light sources may be provided on the mounting surface of the circuit board, in addition to the light source mounting area, and one or more temperature detection units may be provided in the empty area between the light source mounting area and the light source control unit.

[0065] In this design, it is assumed that a light source control unit is provided on the mounting surface of the circuit board. One or more temperature detection units (in other words, at least one temperature detection unit) are provided in the empty area (empty space) between the light source mounting area and the light source control unit on the mounting surface.

[0066] According to this solution, a thermal pattern with high thermal conductivity is used to effectively transfer the heat generated in the light source mounting area to the temperature detection unit, and then the heat can be effectively transferred to the light source control unit located near the temperature detection unit.

[0067] Therefore, based on high-precision temperature detection results, it is possible to implement high-precision temperature suppression measures at the appropriate time.

[0068] Furthermore, in this solution, since the empty space on the circuit board is effectively utilized, it is possible to install highly integrated devices (in other words, a compact circuit board with little useless empty space).

[0069] In the tenth embodiment, which belongs to any of the first to ninth embodiments, a multilayer FR-4 substrate may be used as the circuit substrate, wherein the multilayer FR-4 substrate forms conductive through-members that penetrate each layer.

[0070] In this design, a multilayer (e.g., 4-layer) FR-4 substrate is used. The FR-4 substrate is a circuit board made primarily of glass fiber cloth and epoxy resin, and it possesses excellent properties in terms of electrical insulation, mechanical strength, thermal stability, and flame retardancy.

[0071] Therefore, the FR-4 substrate facilitates effective heat conduction through thermal patterns. In addition, it suppresses thermal instability of the circuit board caused by thermal patterns and ensures stable thermal detection characteristics.

[0072] In this solution, the FR-4 substrate can be multilayered, and through-hole components (specifically, through-holes or contact electrodes embedded in contact holes) can be formed on the multilayered substrate.

[0073] In recent years, the high integration of light sources (light source elements) has continued to develop. In addition to the electrical connection of light source elements, the layout of wiring (conductive patterns) has also been greatly restricted from the perspective of eliminating thermal instability.

[0074] Even with reduced freedom in wiring (conductive pattern) layout, this solution allows for relatively free thermal pattern layout while eliminating thermal instability by effectively utilizing inner layer patterns in a multilayer circuit board (e.g., the ability to set upper and lower patterns). Therefore, it also makes it easier to address the high integration of light sources.

[0075] In the eleventh embodiment, the display device includes a light source device according to any one of the first to tenth embodiments, and a display section that displays an image by emitting light from the light source device.

[0076] According to this solution, a display device equipped with a light source device (light source unit) can be realized, which can effectively protect the light source (the light source in the backlight unit) from the deterioration of light emission characteristics or equipment damage caused by thermal factors.

[0077] In the twelfth embodiment, the method for mounting the light source device includes the following steps: arranging a plurality of light sources in a light source mounting area on a mounting surface of a circuit board; arranging at least one temperature detection unit on the mounting surface outside the light source mounting area; and setting a thermal pattern having a main part and a connecting part, the main part collecting heat generated by the emission of at least one of the plurality of light sources at any position, the connecting part being thermally connected to the temperature detection unit and transferring heat from the main part to the temperature detection unit. In the case where the direction perpendicular to the mounting surface of the circuit board is set as the vertical direction, the direction on the mounting surface side is set as the upward direction, and the direction opposite to the upward direction is set as the downward direction, and the circuit board includes a surface layer on which the plurality of light sources are mounted, and at least one inner layer disposed below the surface layer separated by an electrically insulating film, in the step of setting the thermal pattern, the main part of the thermal pattern, viewed from above, overlaps with the light source mounting area and is disposed in the inner layer.

[0078] According to this solution, a display device with a light source device that fully implements heat-relief measures for the light source can be realized.

[0079] Those skilled in the art will readily understand that the illustrated solutions according to the present invention can be further modified without departing from the spirit of the invention. Attached Figure Description

[0080] Figure 1 This is a diagram illustrating an example of the overall structure of a display device, including a light source.

[0081] Figure 2 This is a diagram illustrating an example of the structure for driving each light source (LED) in a light source device employing a local dimming driving method.

[0082] Figure 3 This is a diagram illustrating an example of a circuit structure for controlling temperature when a thermistor is used as the temperature sensing element and a cooling element is used to suppress the temperature.

[0083] Figure 4 This is a diagram illustrating an example of the layout structure on the mounting surface of a circuit board that employs a structure that uses thermal patterns to transfer heat to a temperature sensing section.

[0084] Figure 5 It is shown Figure 4 A diagram showing an example of the configuration of the grounding pattern, the anode electrode, the cathode electrode, etc. of the LED in the layout structure (corresponding to the layout structure of the local dimming driver).

[0085] Figure 6 It is along Figure 5 A sectional view of line A-A' in the diagram.

[0086] Figure 7 This is a diagram illustrating an example of the configuration in each layer of a 4-layer FR-4 substrate.

[0087] Figure 8 This is a diagram showing an example layout where the branch wiring, which is the main part of the thermal pattern, is set to a curved shape. Detailed Implementation

[0088] The preferred embodiments described below are for the purpose of facilitating understanding of the invention. Therefore, those skilled in the art should note that the invention is not unduly limited to the embodiments described below.

[0089] (First Implementation) refer to Figure 1 . Figure 1 This is a diagram illustrating an example of the overall structure of a display device, including a light source.

[0090] In addition, Figure 1 In this context, the left-right direction on the paper (in other words, the circuit board 50) is sometimes referred to as the X direction, the longitudinal direction perpendicular to the X direction is referred to as the Y direction, and the direction perpendicular to both the X and Y directions (the direction perpendicular to the mounting surface of the paper or the circuit board 50), i.e., the up-down direction, is referred to as the Z direction.

[0091] In addition, regarding the vertical direction, the direction on the side of the mounting surface is sometimes called the vertical direction (+Z direction), and the direction on the opposite side of the vertical direction is called the vertical direction (-Z direction).

[0092] Additionally, in the following description, the expression "top view viewed from above (+Z direction)" is used, but the above "top view" can be replaced with "perspective top view (in a perspective top view)". Specifically, for example, regarding the thermal pattern located below the electrical insulation layer, this is a top view of the thermal pattern when viewed from above in a perspective view of the electrical insulation layer.

[0093] exist Figure 1 In the display device 10, there is a panel driving unit 12 that inputs image data VD, a liquid crystal panel (hereinafter sometimes referred to as "display unit") 14 driven by the panel driving unit 12, a display control unit (display control device) 16 that controls the display of images in the display device, and a light source device 18 disposed on the back of the liquid crystal panel (display unit) 14.

[0094] The light source device 18 has a circuit board (or light source board) 50 on the back side of the liquid crystal panel (display unit) on which a light source (in other words, a light source element such as an LED) is mounted.

[0095] A circuit board 50 is mounted on the light source device 18. The light source device 18 has a backlight section 20.

[0096] The backlight unit 20 includes: a light source mounting area 22 on which a light source (such as an LED (light-emitting diode) is mounted on the circuit board 50; at least one temperature detection unit (such as a temperature detection unit including a thermistor 31) 32 disposed outside the light source mounting area 22 (outside a predetermined end of the light source area 22); a light source control unit 34 (including a light source driving unit 35); and a temperature suppression unit 36. Furthermore, the temperature suppression unit 36 ​​may also be disposed within the display control unit (display control device) 16, for example.

[0097] The light source mounting area 20 has a rectangular (quadrilateral) shape when viewed from above (+Z direction).

[0098] In addition, the light source mounting area 22 is provided with a light source group 24 consisting of a plurality of light sources (LEDs, etc.) 25 disposed on the circuit board 50 (specifically mounted on the surface), a thermal pattern 26, and a cooling element (here a Peltier element) 28 as a countermeasure element to suppress the temperature rise of the light source 25.

[0099] The thermal pattern 26 has main portions 26a and 26b and a connecting portion 26c. The main portions 26a and 26b collect heat generated by the emission of light from at least one of the plurality of light sources 25 located at arbitrary positions. The connecting portion 26c is thermally connected to a temperature detection unit (including a thermistor 31) 32 and transfers the collected heat to the temperature detection unit 32.

[0100] exist Figure 1In the example, the main parts 26a and 26b of the thermal pattern can be referred to as "branch wiring or branch pattern" branching off from the connecting part 26c.

[0101] In addition, the main part of the thermal pattern can also be a solid pattern in the shape of a surface. In this case, the solid pattern in the shape of a surface can, for example, collect and transfer the heat of all the LEDs located in the light source mounting area to the connection part 26c.

[0102] For example, copper (or an alloy with nickel, iron, etc.) with excellent thermal conductivity can be used as the thermal pattern 26.

[0103] The "branch wirings 26a and 26b, which are the main parts of the thermal pattern" can be described as "parts extending from the side of the second end (opposite to the side of the first end) in the light source mounting area 22, opposite to the side where the temperature detection unit 32 is located, toward the side of the first end, and whose main function is heat collection (in other words, heat collection parts)". The shape of the branch wirings 26a and 26b, which are the main parts of the thermal pattern 26, is as follows: Figure 1 The example shows a straight line, but it is not limited to this; it can also be a curved shape (regarding this, we will use...). Figure 8 (Explanation to be provided).

[0104] Furthermore, the "connecting part 26c" can be described as "the part that thermally connects the aforementioned main parts 26a and 26b to the temperature detection unit 32, and whose main function is to transfer the collected heat to the temperature detection unit 32." The shape of this connecting part 26c can be appropriately set according to the relative positional relationship between the temperature detection unit (thermistor, etc.) 32 and the thermal pattern 26. Details regarding the thermal pattern 26 will be discussed later. Figures 4-7 The explanation is as follows.

[0105] Furthermore, as the circuit board 50, for example, a multilayer FR-4 substrate with excellent heat resistance can be used (details on this can be found in...). Figure 6 , Figure 7 (This is explained in the text).

[0106] The multilayer FR-4 substrate 50 may have a surface layer and at least one inner layer. The inner layer is disposed below the surface layer, separated by an electrical insulating layer (an electrical insulating layer mainly composed of glass fiber cloth and epoxy resin). Furthermore, as an inner layer pattern disposed on the inner layer, an upper pattern on the mounting surface side and a lower pattern on the back side opposite to the mounting surface may be provided.

[0107] The main parts 26a and 26b of the thermal pattern 26, when viewed from above (+Z direction), are wired as the inner layer pattern, overlapping with the light source mounting area 22.

[0108] In other words, the thermal pattern 26 (the main parts of the thermal pattern 26a, 26b) can be positioned directly below each light source (e.g., each LED) 25. In this case, when viewed from above, at least a portion of the thermal pattern overlaps with the light source (LED) 25.

[0109] Therefore, even if the position of the temperature detection unit 32 is separated from the position of the light source (LED, etc.) that serves as the heat source, the heat can still be transmitted through the thermal pattern 26 via the electrical insulating layer. Figure 1 Not shown in the image. Figure 3 The symbol 70) effectively collects the heat generated from the light source (LED) 25 and effectively (in other words, with reduced heat loss) transfers it to the temperature detection unit 32.

[0110] Therefore, even if the temperature sensing unit 32 is located outside the light source mounting area 22, the temperature of the light source 25 or the circuit board 50 can be detected (estimated) with good accuracy. As a result, in the light source device, it is possible to simplify the installation of the temperature sensing unit 32 and improve the accuracy of temperature measurement.

[0111] In addition, although a light source (such as an LED) 25 is arranged on the mounting surface of the circuit board 50, the light source 25 is not arranged on the inner layer located below the surface of the circuit board 50, leaving more free space. Therefore, the degree of freedom in arranging the thermal pattern 26 is high.

[0112] Therefore, considering the installation status of the light source 25, such as the shape of the light source installation area 22, the configuration of the light source 25, the configuration density of the light source 25, the configuration of the signal line supplying the signal to the light source 25 or the grounding, a pattern with higher heat collection or heat transfer performance (optimal pattern) can be set.

[0113] Therefore, the shapes of the branch lines 26a and 26b, which are the main part of the thermal pattern 26, when viewed from above can be as follows: Figure 1 The image shown is a straight line, but it can also be like... Figure 8 The curve shown is the shape of the curve. In addition, the width and length of the straight lines in branch lines 26a and 26b, as well as the curvature, width, and length of the curves, can also be determined relatively freely.

[0114] The temperature detection unit (including a thermistor 31, etc.) 32 detects (estimates) the temperature of the light source 25 or the circuit board 50 based on the temperature of the thermal pattern (thermal wiring) 26. The light source control unit 34 implements predetermined countermeasures based on the detected temperature.

[0115] An example of the control steps in countermeasures is as follows.

[0116] The thermistor 31, which is a temperature sensing element included in the temperature sensing unit 32, continuously measures the temperature of the thermal pattern 26 and supplies a temperature detection signal SQ1 (step S1) to the display control unit (display control device) 16.

[0117] The display control unit (display control device) 16 sends a light emission control signal SQ2 to the light source control unit 34 based on the temperature detection signal SQ1, which controls the light emission state of the light source (LED) 25. In addition, the display control unit (display control device) 16 determines whether the temperature of the light source 25 or the circuit board 50 exceeds a predetermined threshold (step S2).

[0118] If the threshold is exceeded, the light source control unit 34, which receives the light emission control signal SQ, performs a predetermined thermal countermeasure (step S3) because thermal countermeasures are required to suppress the degradation of the light source 25 caused by the temperature rise.

[0119] There are various ways to implement this countermeasure. For example, from the perspective of protecting the light source, derating (driving the light source with a current (or voltage) lower than the rated value to suppress light emission) can be implemented. Alternatively, cooling units such as fans or cooling elements can be used to cool the light source. Or, the brightness and output of the light source can be optimized to minimize power consumption while maintaining the required amount of light emission. Furthermore, the above countermeasures can be combined with measures such as issuing warnings.

[0120] exist Figure 1 In this embodiment, as a heat countermeasure, the light source drive unit 35 in the light source control unit 34 supplies a light source drive control signal SQ3 to the light source group 24 to enhance the derating of the light source, and in conjunction with this, a cooling element 28 (e.g., a Peltier element) is used to cool the light source 25 (or the circuit board 50), which can suppress temperature rise. Furthermore, it is also possible to optimize the brightness and output of the light source 25, and minimize power consumption while maintaining the required light emission. Moreover, the cooling element 28 (e.g., a Peltier element) can be omitted.

[0121] When the cooling element 28 is used, the light source control unit 34 supplies a temperature suppression control signal SQ4 to the temperature suppression unit 36, and accordingly, the temperature suppression unit 36 ​​drives (starts) the cooling element (Peltier element) 28.

[0122] Furthermore, when the method of optimizing the brightness and output of the light source 25 is adopted, the light source drive unit 35 of the light source control unit 34 supplies a light source drive control signal SQ3 to the light source group 24, thereby suppressing the brightness and other properties of the light source 25 to be controlled.

[0123] Furthermore, if the temperature of the light source 25 (circuit board 50) falls below a predetermined threshold, the light source control unit 34 performs a process that interrupts the heat countermeasures process or reduces the degree of the heat countermeasures process (including restoring it to its initial state) (step S4).

[0124] In addition, if the brightness of the light source 25 is adjusted due to the temperature rise of the light source 25, the light source control unit 34 may also supply a notification signal indicating the situation to the display control unit (display control device) 16.

[0125] The display control unit (display control device) 16 and the panel driving unit 12 exchange control signals SQ5 and SQ6. Upon receiving the notification signal SQ5, the panel driving unit 12 determines whether it is necessary to adjust the brightness of the displayed image, etc., based on the brightness suppression processing of the light source 25. If necessary, it supplies a liquid crystal driving signal (including a liquid crystal control signal) SQ7 to the liquid crystal panel (display unit) 14 to appropriately adjust the brightness of the displayed image, etc.

[0126] Next, refer to Figure 2 . Figure 2 This diagram illustrates an example of the structure for driving individual light sources (LEDs) in a light source device employing a local dimming driving method. Figure 3 In the figures, the same symbols are used for parts that are common to the aforementioned figures.

[0127] exist Figure 2 In the middle, a total of 20 LEDs (LED11 to LED54) are arranged in a matrix of 5 columns and 4 rows.

[0128] The anode AE ​​(refer to LED11) of each LED (LED11 to LED54) is connected to the scan line (LN1 to LN5), and the cathode KE (refer to LED11) is connected to the signal line (LM1 to LM4).

[0129] LED dimming units 19a to 19d are connected to signal lines (data lines) LM1 to LM4 respectively, and dimming control signals PCa to PCd are input to each LED dimming unit 19a to 19d respectively.

[0130] In front Figure 1 The light-emitting drive control signal SQ3 described herein includes the aforementioned dimming control signals PCa to PC.

[0131] Each LED dimming section 19a to 19d includes a variable resistor 60 for variable control of the constant current value in the LED driver, and a PWM switch 62 (e.g., composed of a MOSFET) for generating pulse-width modulated pulses (PWM pulses). The resistance value of the variable resistor 60, the switching time of the PWM switch 62, and the switching timing are controlled by dimming control signals PCa to PCd.

[0132] In addition, one end of the variable resistor 60 is grounded.

[0133] LEDs 11 to 54 correspond to scan lines LN1 to LN5 respectively, and are divided into regions MX1 to MX5.

[0134] In order to select each region MX1 to MX5 sequentially by scanning lines LN1 to LN5, a region selection switch 51 with contacts W1 to W5 is provided.

[0135] When a contact (any one of W1 to W7) is selected using the area selection switch 51, the corresponding scan line (any one of LN1 to LN5) is connected to the power supply (battery) 61 via that contact, and the power supply voltage is supplied to the scan line. As a result, the LEDs with anodes AE connected to that scan line are forward biased, generating a forward voltage, and these LEDs emit light. The brightness of the LEDs (luminous intensity) can be controlled by a constant current value determined by the resistance value of the variable resistor 60, and by the pulse width of the PWM pulse determined by the opening and closing of the PWM switch 62.

[0136] Next, refer to Figure 3 . Figure 3 This is a diagram illustrating an example of a circuit structure for controlling temperature when a thermistor is used as the temperature sensing element and a cooling element is used to suppress temperature.

[0137] In the thermistor 31 included in the temperature detection unit 32, the resistor 36 is connected in series with respect to the reference voltage source 33.

[0138] Here, thermistor 31 functions as a variable resistor whose resistance changes with temperature. Thermistor 31 and resistor 36 function as voltage divider resistors for dividing the reference voltage VE generated by reference voltage source 33.

[0139] The voltage obtained by voltage division (detection voltage) is amplified by the amplifier circuit 38 in the light source drive unit 35 included in the light source control circuit 34, and converted into a digital signal (temperature detection signal) SQ1 by the A / D converter 40.

[0140] The converted digital signal (temperature detection signal) SQ1 is supplied to the display control unit (display control device) 16.

[0141] The display control unit (display control device) supplies a light source control signal SQ2 to the light source control unit 34 (specifically, the light source driving unit 35) based on the temperature detection signal SQ1.

[0142] The light source control signal SQ2 includes control as previously... Figure 2 The first pulse width control signal PWM1 for the MOSFET on / off time of the PWM switch 62 and the first variable resistance value control signal (PAM1) for controlling the variable resistance value of the variable resistor 60 are shown in the figure.

[0143] The light source driving unit 35 supplies the second pulse width control signal PWM2 and the second variable resistance value control signal (PAM2) to the LED, which serves as the light source 25, based on the supplied light source control signal. Furthermore, PWM2 and PAM2 can also be the same signals as PWM1 and PAM1.

[0144] In addition, the light source control signal SQ2 may also include a determination signal indicating whether countermeasures to suppress temperature are required.

[0145] When it is determined that temperature suppression is required, the temperature control unit TC, including the light source control unit 34, supplies a temperature suppression control signal SQ2 to the temperature suppression unit 36. Accordingly, the temperature suppression unit 36 ​​drives (activates) the cooling element (Peltier element) 28.

[0146] The LED 25, which serves as the light source, is placed on a sub-substrate (or heat sink) 27 with high thermal conductivity. When the cooling element (Peltier element) 28 is driven (activated), the LED 25 is cooled via the sub-substrate (or heat sink) 27, and the temperature of the LED 25 is suppressed.

[0147] Next, refer to Figure 4 . Figure 4 This is a diagram illustrating an example of the layout structure on the mounting surface of a circuit board employing a structure that uses thermal patterns to transfer heat to the temperature detection section (a layout structure corresponding to local dimming drive). Furthermore, in Figure 4 In the middle, to and Figure 1 Common parts are marked with the same symbol.

[0148] exist Figure 4 In the circuit board 50, a light source device 18 and a backlight section 20 are provided. In the light source device 18 (backlight section 20), the light source mounting area 22 is divided into three segmented areas Z1 to Z3 corresponding to the local dimming drive.

[0149] In each segmented region Z1 to Z3, the light sources (LEDs) 25 are arranged in a matrix (grid) pattern. The above matrix can be represented by a 5x8 matrix.

[0150] Furthermore, when viewed from above (+Z direction), the light source mounting area 22 and each segmented area Z1 to Z3 have a rectangular (quadrilateral) shape.

[0151] For example, in the segmented region Z1, the main parts 26a and 26b of the thermal pattern 26 are arranged parallel to each other.

[0152] Each main part 26a, 26b extends in a straight line from the second end of the light source mounting area 22 (or the segmented area Z1) opposite to the end on the side where the temperature detection part (thermistor) 32 is located, toward the first end along the column direction of the matrix.

[0153] In addition, the connecting part of the thermal pattern 26 connects the main parts 26a and 26b (branch wiring 26a and 26b) of the two thermal patterns together, and the part that is connected together is thermally connected to the temperature detection unit 32.

[0154] In other words, the light source mounting area 22 is divided into multiple rectangular segments Z1 to Z3 in a manner corresponding to the local dimming drive of the multiple light sources 25. The temperature detection unit 32 is disposed in each segment Z1 to Z3 on the outside of a predetermined end (the first end near the side of the temperature detection unit 32) of each segment Z1 to Z3. The end of the branch wiring 26a, 26b, which is the main part of at least one thermal pattern 26, is thermally connected to the temperature detection unit 32 via a connecting part (connecting pattern) 26c.

[0155] As described above, in the prior art, when a local dimming driving method is used, the light source 25 at any position will be lit in conjunction with the displayed image. Therefore, when the position of the light source 25 is far away from the temperature detection unit 32, heat cannot be fully transferred to the temperature detection unit 32, resulting in a delay in the timing of implementing heat-generating countermeasures, or it can be imagined that the accuracy of heat-generating countermeasure processing will decrease.

[0156] according to Figure 4 With this structure, the aforementioned existing problems are solved. Furthermore, in Figure 4 In this structure, since heat can be effectively transferred to the temperature detection unit 32 via the thermal pattern 26 with high thermal conductivity, the temperature detection unit 32 can be arranged outside the predetermined end (first end) of the light source mounting area 22, and the layout related to the arrangement of the temperature detection unit 32 becomes easier.

[0157] Furthermore, regarding the aforementioned "predetermined end (first end, or alternatively, predetermined boundary line)," specifically, one of the four sides of the rectangle (quadrilateral), or the vicinity of that side, can be used as the predetermined end (or predetermined boundary line).

[0158] A temperature detection unit 32 is provided for each segmented region Z1 to Z3. This temperature detection unit 32 is located outside the light source mounting area 22, at a position corresponding to the center of the first end in the left-right direction. The same structure is applied to segmented regions Z2 and Z3.

[0159] Furthermore, on the circuit board 50, each segmented region Z1 to Z3 is provided with an IC1 (integrated circuit), and an additional IC2 (integrated circuit) is provided. IC1 integrates... Figure 1 The light source control unit 34 and temperature suppression unit 36 ​​are described in the diagram. These are integrated into IC2. Figure 1 The display control unit (display control device) 16 shown is shown.

[0160] In addition, multiple vias 60, 62, etc., are provided on the circuit board 50. For example, via 60 is used to ensure the ground plane ( Figure 4 Not shown in the image. Figure 5 The via 62 is provided for electrical connection of the LED cathode KE (symbol GP) installed on the mounting surface, and is also provided, for example, to ensure electrical connection of the LED cathode KE, which serves as the light source 25 (see reference). Figure 7 ).

[0161] Next, the specific configuration of the thermal pattern 26 will be explained.

[0162] exist Figure 4 As described above, in each segmented region Z1 to Z3, the light source (LED) 25 is arranged in a matrix (grid) shape, which can be represented by a 5x8 matrix.

[0163] In each segmented region Z1 to Z3, when viewed from above (+Z direction), all (or part) of the branch wirings 26a and 26b, which are the main parts of the linear thermal pattern 26, overlap with the light source 25 (referred to as the "first light source") corresponding to a column of the matrix in the second row and a column of the matrix in the fourth row.

[0164] In other words, all (or part) of the branch wirings 26a and 26b, which constitute the main part of the thermal pattern 26, overlap only with the "first light source" among the multiple light sources 25. This means that for the aforementioned "first light source 25," branch wirings 26a and 26b are provided directly below the light source 25. Because an electrical insulating layer separates the light source 25 from the branch wirings 26a and 26b... Figure 5 The symbol 70) has branch wiring 26a and 26b, so the heat generated by the light source 25 is effectively transferred to the branch wiring 26a and 26b, which are located directly below the light source 25 and function as heat collection parts, thereby improving the heat collection performance of the thermal pattern 26.

[0165] On the other hand, the light sources 25 that correspond to the matrix of one column in the first row, one column in the third row, and one column in the fifth row do not overlap with the aforementioned branch wiring 26a and 26b. These light sources 25 are referred to as "second light sources".

[0166] Here, the arrangement of the matrix-shaped light sources 25 is regular, and the spacing (interval) between a light source 25 and the light source 25 adjacent to it is in principle the same.

[0167] Therefore, the branch wirings 26a and 26b of the main part of the thermal pattern 26 are configured in such a way that the shortest distance between the light source 25, which is equivalent to the above-mentioned "second light source", and the branch wirings 26a and 26b of the main part of the thermal pattern 26 are in principle the same, or even with some exceptions, the branch wirings 26a and 26b of the main part of the thermal pattern 26 are configured in such a way that the shortest distance falls within a predetermined allowable range.

[0168] In other words, the aforementioned "second light source" does not overlap with the branch wirings 26a and 26b, but is configured such that the light source 25, which is equivalent to the "second light source", has the same shortest distance as the branch wirings 26a and 26b (in other words, equal distance), or the shortest distance between each light source 25 and the branch wirings 26a and 26b falls within a predetermined allowable range.

[0169] In other words, for the aforementioned "second light source", the deviation of the shortest distance between the light source 25 viewed from above (+Z direction) and the branch wirings 26a and 26b, which are the main parts of the thermal pattern 26, falls within a predetermined allowable range.

[0170] Therefore, it is possible to suppress (e.g., minimize) the deviation in heat collection performance when the branch wirings 26a, 26b, which are the main parts of the thermal pattern, collect heat generated from each light source 25.

[0171] Furthermore, although the distance between the light source 25 and the temperature detection unit 32 may vary depending on the position of each light source 25, the thermal pattern 26 is made of materials such as copper and its alloys with high thermal conductivity, and the resistance in heat conduction is extremely small. Therefore, the aforementioned change in distance can be ignored.

[0172] Therefore, according to Figure 3 The structure allows the heat from each light source 25 to be transmitted to the temperature detection unit 32 with good (in other words, accurately) even if each light source 25 is assumed to emit light and generate heat independently.

[0173] In addition, the 5-row, 8-column matrix mentioned above can be more broadly referred to as an m-row, n-column matrix (where m is an integer greater than 4 and n is an integer greater than 2).

[0174] In this matrix, Figure 4 In the example, the linear branch wirings 26a and 26b, which are the main part of the thermal pattern 26, are configured such that all or part (preferably all) of them overlap only with the light source 25 of the matrix corresponding to a row that is a multiple of 2 (e.g., the matrix in the second row and first column when m is 2).

[0175] The light sources corresponding to the matrices in rows 2 and 4 (hereinafter the same) are equivalent to the "first light source" described above. Directly below these light sources 25, there will be branch wirings 26a and 26b, which are the main parts of the thermal pattern 26. For these light sources 25, the heat generated from each light source 25 passes through an electrically insulating film ( Figure 6 The symbol 70) is transmitted to the branch wiring 26a, 26b with the shortest distance, thus achieving effective heat collection.

[0176] On the other hand, the light sources 25 corresponding to the first, third, and fifth rows (hereinafter the same) of the matrix are equivalent to the "second light sources" described above. As mentioned above, when viewed from above (+Z direction), the shortest distance between each light source 25 and the branch wirings 26a and 26b, which are the main parts of the thermal pattern 26, is the same (equal distance), and each light source 25 is equally arranged near the main parts 26a and 26b of the branch wirings 26. Therefore, there is no deviation in the heat collection of each light source 25, and effective heat collection can be achieved for any light source 25.

[0177] Additionally, due to certain circumstances (e.g., layout reasons with other wiring (ground wires or signal lines), the aforementioned minimum distances may vary. However, as stated above, as long as the deviations of each minimum distance fall within a predetermined allowable range, deviations in heat collection performance when the thermal pattern 26 collects heat generated from each light source 25 can be suppressed (e.g., minimized).

[0178] Therefore, according to Figure 4 In the example of thermal pattern configuration, regardless of the location of the light source 25, the temperature rise of the circuit board 50 (or each light source 25) caused by the heat generated by the light source 25 can be detected with good accuracy.

[0179] In other words, even if the light source 25 in a portion of the light source mounting area 22 emits light locally, the temperature rise of the circuit board 50 caused by the localized heating can be detected with good accuracy, regardless of the relative position of the portion of the light source mounting area 22 to the light source mounting area 22.

[0180] Therefore, according to Figure 3The configuration example of the thermal pattern 26 enables the implementation of highly precise countermeasures to suppress the temperature rise at the appropriate time.

[0181] In addition, Figure 4 In this circuit board 50, on the mounting surface 80, in addition to the light source mounting area 22, there is also an IC1 that has a light source control unit 34 for controlling the driving of multiple light sources 25. A temperature detection unit 32 (multiple temperature detection units 32 depending on the situation) is provided in the empty area 82 between the light source mounting area 22 and the IC1 with the light source control unit 34. In other words, at least one temperature detection unit 32 is provided in the empty area (empty space) 82 between the light source mounting area 22 and the light source control unit 34 on the mounting surface 80.

[0182] According to this layout, a thermal pattern 26 with high thermal conductivity is used to effectively transfer the heat generated in the light source mounting area 22 to the temperature detection unit 32, and then the heat can be effectively transferred to the light source control unit 34 located near the temperature detection unit 32. Therefore, based on the high-precision temperature detection results, high-precision temperature suppression measures can be implemented at the appropriate time.

[0183] Furthermore, based on the above layout structure, since the empty area 82 on the circuit board 50 is utilized, the installation of highly integrated devices can be achieved (in other words, a small circuit board 50 with little useless empty area).

[0184] In addition, Figure 4 In the top view (+Z direction), the pattern thickness of the branch wirings 26a and 26b, which are the main part of the thermal pattern 26, is depicted as being almost equal to the width of each of the multiple light sources 25 in the direction corresponding to the thickness of the branch wiring 26.

[0185] However, this is not the only option. Depending on the circumstances, the pattern thickness of the branch wirings 26a and 26b can also be set to be thinner than the width of the light source (light source device) 25.

[0186] As mentioned above, the integration of light sources 25 has been continuously developing in recent years, and the spacing between light sources 25 has tended to be narrower. Furthermore, the lower plane in the inner layer of the circuit board 50 can potentially have a ground plane disposed at any location. Figure 5 (symbol GP), wiring for connecting to signal lines, through vias (or contact electrodes, etc.): Figure 7 The symbol VA).

[0187] Even in this case, if the width of the branch wirings 26a and 26b is set to be narrower than the width of the light source (light source device) 25, the area occupied by the thermal pattern 26 will be smaller. As a result, the thermal plane 26 can be configured relatively freely to accommodate situations such as narrower spacing of each light source 25 and reduced freedom of configuration of the thermal pattern 26 in the lower layer (lower plane) of the circuit board.

[0188] (Second Implementation) Next, refer to Figure 5 . Figure 5 It is shown Figure 4 A diagram illustrating an example of the configuration of the grounding pattern, the anode electrode, and the cathode electrode of the LED in a layout structure (corresponding to the layout structure of a local dimming driver). Figure 5 In the figures, the same symbols are used for parts that are common to the aforementioned figures.

[0189] exist Figure 5 In this context, grounding includes a ground plane GP with a wide wiring width and a ground wire GW with a narrower wiring width branching off from the ground plane GP.

[0190] exist Figure 5 In this configuration, the ground plane GP is not positioned around the branch wirings 26a and 26b, which are the main part of the thermal pattern 26, but is positioned outside the light source mounting area 22.

[0191] However, it is not limited to this. The ground plane GP can also be set in a position (empty area, etc.) away from the branch wirings 26a, 26b that are the main part of the thermal pattern 26 within the light source mounting area 22.

[0192] This prevents the heat emitted by the light source 25 from escaping to the wider ground plane GP.

[0193] Since the heat from the light source 25 does not escape to the ground plane GP but is transferred to the main parts 26a and 26b of the thermal pattern 26, there is no decrease in heat collection caused by the main parts 26a and 26b of the thermal pattern 26, and high heat collection is always achieved.

[0194] In addition, Figure 5 The diagram depicts the patterns of the anode (anode electrode) AE and cathode (cathode electrode) KE of each light source 25.

[0195] In addition, Figure 5 In order to avoid complicating the accompanying drawings, the patterns of the anode (anode electrode) AE and cathode (cathode electrode) KE of each light source 25 are depicted only on the light source 25 corresponding to the position of the branch wiring 26a.

[0196] The cathode electrode KE also functions as a heat dissipation component, which dissipates the heat emitted by each light source 25 to the branch wirings 26a and 26b, which are the main part of the thermal pattern 26 located directly below. Therefore, the heat collection efficiency of the branch wirings 26a and 26b is improved.

[0197] In addition, Figure 5 In the diagram, the symbol 26d is marked at the end of the connecting part 26c of the thermal pattern 26.

[0198] This is because, relative to the pattern provided in the inner layer of the circuit board 50, the connection portion 26c is a pattern provided in the aforementioned surface layer, so a separate symbol is marked (see reference). Figure 6 ).

[0199] Next, refer to Figure 6 . Figure 6 It is along Figure 5 A sectional view of line A-A' in the diagram.

[0200] exist Figure 6 In the example, a 4-layer FR-4 substrate is used as the circuit board 50. Figure 6 In the middle, the symbols 50-1 to 50-4 are marked on the first to fourth layers of the board.

[0201] The multilayer (4-layer) circuit board 50 can also form conductive through-parts (not shown) that penetrate each layer 50-1 to 50-4 (see reference). Figure 7 The symbol VA).

[0202] In this case, for example, a conductive pattern GS is provided on the back side of the first layer.

[0203] The conductive pattern GS is, for example, equivalent to Figure 7 The signal electrode SE-1UN is located in the first layer.

[0204] In addition, Figure 6 In the fourth layer 50-4, the electrically insulating layer 70 is locally patterned to form shallow trenches, within which a cathode electrode KE is formed. Furthermore, the cathode electrode KE is formed as the upper pattern of the surface layer, i.e., the fourth layer.

[0205] Furthermore, the branch wiring 26a and the connecting portion 26c, which are the main parts of the thermal pattern 26, are formed as the lower part of the third layer 50-3. Since the branch wiring 26 is located directly below the LED, which serves as the light source 25, it can effectively collect the heat HE generated from the light source 25.

[0206] In addition, the end of the connecting part 26c (in other words, the end connected to the temperature detection part 32) 26d is formed as the upper pattern (surface pattern) of the fourth layer 50-4.

[0207] The connecting part 26c and its end 26d are connected via the contact part 29 (thermal).

[0208] As mentioned above, in Figure 6 A multi-layer (4-layer) FR-4 substrate was used. FR-4 substrates are typically circuit boards made primarily of fiberglass cloth and epoxy resin, exhibiting excellent properties in terms of electrical insulation, mechanical strength, thermal stability, and flame retardancy. Therefore, the FR-4 substrate facilitates effective heat conduction through the thermal pattern 26, and also suppresses thermal instability of the circuit board 50 caused by the thermal pattern 26, thus ensuring stable thermal detection characteristics.

[0209] Furthermore, as described above, through-hole components (specifically, through-holes or contact electrodes embedded in contact holes, etc.) can be formed on the multilayered FR-4 substrate; see reference. Figure 7 The symbol VA).

[0210] In recent years, the integration of light sources (light source elements) 25 has continued to develop. In addition to the electrical connection of light source elements 25, the layout of wiring (conductive patterns) has also been greatly restricted from the point of view of eliminating thermal instability.

[0211] Even with reduced degrees of freedom in the layout of wiring (conductive patterns), according to Figure 6 The structure allows for the placement of upper or lower patterns in the inner layers of each of the multi-layered structures, specifically layers 50-1 to 50-4, namely layer 50-2 and layer 50-3. Therefore, by effectively utilizing these patterns, the layout of the thermal pattern 26 can be relatively freely arranged while eliminating thermal instability. Consequently, the high integration of the light source 25 can be addressed more easily.

[0212] The method for manufacturing the multilayer circuit board 50 (in other words, the mounting method for the light source device 18) includes, for example, the steps of: setting a plurality of light sources 25 in a light source mounting area 22 on a mounting surface 80 of the circuit board 50; setting at least one temperature detection unit 32 on the mounting surface 80 outside the light source mounting area 22; and setting a thermal pattern 26 having a main portion and a connecting portion, the main portion collecting heat generated by the emission of at least one light source 25 located at any position among the plurality of light sources 25, and the connecting portion being thermally connected to the temperature detection unit and storing the collected heat. Heat is transferred to the temperature detection unit 32. When the direction perpendicular to the mounting surface 80 of the circuit board 50 is set as the up-down direction, the direction on the side of the mounting surface 80 is set as the up direction, and the direction opposite to the up direction is set as the down direction, and the circuit board includes a surface layer on which multiple light sources are mounted, and an inner layer with at least one layer disposed on the underside of the surface layer through an electrically insulating film, in the above-mentioned step of setting the thermal pattern 26, the main parts 26a and 26b of the thermal pattern 26 are wired as the inner layer pattern in a top view (perspective top view in perspective top view) that overlaps with the light source mounting area 22.

[0213] (Third Implementation) Next, refer to Figure 7 . Figure 7 This is a diagram illustrating an example of the configuration in each layer of a 4-layer FR-4 substrate.

[0214] exist Figure 7 In the middle, below the LED that serves as the light source 25, the cathode electrode KE (SE-4UP) of the LED is configured as the upper pattern of the fourth layer (surface layer).

[0215] Furthermore, the aforementioned “SE-4UP” designation indicates that the electrode SE is provided as the upper pattern (UP) of the fourth layer 50-4.

[0216] Additionally, for example, branch wiring 26a, which is the main part of thermal wiring 26, is described as SE-3UN. This indicates that the electrode SE is provided as the lower pattern (UN) of the third layer 50-3. Other descriptions are similar.

[0217] The electrode SE-1UN in the first layer is connected to the one previously used in Figure 2 The MOSFET 62 and variable resistor 60 are connected in series as a PWM switch as described in the diagram.

[0218] exist Figure 7 In the middle, the through electrode (through via) VA electrically connects the electrodes SE-1UN, SE-2UP, SE-3UP, and the cathode electrode KE (SE-4UP) of the fourth layer (surface layer) of LED25.

[0219] In addition, as described above, since the LED cathode electrode KE, which serves as the light source 25, also acts as a heat sink, the amount of heat HE transferred to the branch wiring 26a, which is the main part of the thermal pattern 26, is also increased.

[0220] (Fourth Implementation) Next, refer to Figure 8 . Figure 8 This diagram illustrates an example layout where the branch wiring, which forms the main part of the thermal pattern, is curved. Furthermore, in Figure 8 In the figures, the same symbols are used in the parts that are common to the aforementioned figures.

[0221] In addition, Figure 8 The previously described are shown in the figure. Figure 4 The shape of the thermal pattern 26' in segmented region Z1. The same shape of thermal pattern 26' can also be used in other segmented regions Z2 and Z3.

[0222] exist Figure 8 In the middle, the branch wirings 26a' and 26b', which are the main parts of the thermal pattern 26', are formed into curved shapes when viewed from the top (+Z direction) in a top view (perspective top view in perspective top view).

[0223] Although a light source (such as an LED) 25 is arranged on the mounting surface 80 of the circuit board 50, since no light source is arranged in the inner layer of the circuit board 50, there is a lot of free space, so the degree of freedom in arranging the thermal pattern 26' is high.

[0224] Therefore, in Figure 8 In this process, the installation status of the light source 25 can be considered, such as the shape of the light source installation area 22, the configuration of the light source 25, the configuration density of the light source 25, the configuration of the signal line supplying the signal to the light source 25, the configuration of the ground line, etc., and a pattern shape with high heat collection and heat transfer can be selected.

[0225] like Figure 8 As shown, if the branch wirings 26a' and 26b', which are the main part of the thermal pattern 26', are made into curved shapes, the wiring length becomes longer. It is undeniable that the heat transfer efficiency to the temperature detection unit 32 will decrease slightly. However, by appropriately adjusting the wiring width or the degree of wiring curvature, the ease of heat transfer can be adjusted, and the decrease in heat transfer efficiency can be suppressed.

[0226] In addition, regardless of the position of each light source 25 configured as a surface, it is important that the curved thermal pattern 26' has the heat collection performance to collect the heat emitted by each light source 25 as evenly as possible.

[0227] exist Figure 8In the process, the branch wirings 26a' and 26b', which are the main parts of the thermal pattern 26', are each configured in such a way that the shortest distance between them and each of the light sources 25 arranged in a planar shape falls within a predetermined allowable range.

[0228] In addition, Figure 8 In this context, we assume an imaginary center line B-B' extending along the column direction of the light source matrix 25, which bisects the rectangular (quadrilateral) dividing region Z1. Then, the branch wirings 26a' and 26b', which are the main parts of the thermal pattern 26', are arranged in a line-symmetrical manner with respect to the center line B-B'.

[0229] Therefore, regardless of the position of each light source 25 configured in a planar shape, the thermal pattern 26' can have the heat collection performance of collecting the heat emitted by each light source 25 as equally as possible.

[0230] As described above, according to the embodiments of the present invention, the installation of the temperature detection unit and the accuracy of temperature measurement can be improved in the light source device.

[0231] Furthermore, a display device with high reliability can be realized that includes the light source device according to the embodiments of the present invention and the display unit that uses the light source device to emit light to display images.

[0232] In other words, a highly reliable display device is achieved by having a light source device (light source unit) that effectively protects the light source (light source in the backlight unit) from the effects of heat-induced degradation of light emission characteristics, equipment damage, etc.

[0233] The present invention has been described above using several embodiments, but the present invention is not limited to the above embodiments and can be modified and applied in various ways.

[0234] For example, in addition to LEDs, various light-emitting devices such as organic or inorganic electroluminescent elements can be used as light sources.

[0235] In addition, the present invention can also be applied to display devices (light source devices) that do not employ local dimming drive.

[0236] In addition, the shape of the light source installation area is not limited to a rectangle; it can also be other polygons, circles, etc.

[0237] In addition, the materials used for thermal patterns are not limited to copper-based materials; various materials with high thermal conductivity can also be used.

[0238] Furthermore, the shape of the thermal pattern is not limited to the shape described in the embodiment, and can be appropriately deformed, etc.

[0239] In addition, thermocouples or other similar devices can be used as temperature sensing elements in the temperature sensing section, in addition to thermistors.

[0240] In addition, each branch wiring, which is the main part of the thermal pattern, is preferably arranged directly below the light source corresponding to the branch wiring arrangement, but the meaning of "directly below" should be interpreted flexibly and broadly.

[0241] This invention is not limited to the exemplary embodiments described above. Furthermore, those skilled in the art should be able to easily modify the exemplary embodiments described above within the scope of the claims.

[0242] Explanation of reference numerals in the attached figures 10…Display device, 12…Panel driving unit, 14…Liquid crystal panel (display unit), 16…Display control unit (display control device), 18…Light source device, 20…Backlight unit, 22…Light source mounting area, 24…Light source group, 26, 26'…Thermal pattern (thermal wiring), 26a, 26a', 26b, 26b'…Main part of thermal pattern (heat collection part), 26c…Connecting part of thermal pattern, 26d…End of connecting part of thermal pattern (the end provided in the upper part of the inner layer of the circuit board), 27…Sub-board (heat sink), 28…Cooling element (Peltier element, etc.), 32…Temperature detection unit (thermistor, etc.), 33…Reference voltage source, 36…Voltage divider resistor, 34…Light source control unit, 35… …Light source driving section, 36…Temperature suppression section, 38…Amplification circuit, 40…A / D converter, 43…Decision processing section, 50…Circuit board (light source board, mounting board, printed circuit board (PCB)), 50-1 to 50-4…Layer 1 to 4 of the 4-layer circuit board (4-layer FR-4 board), 51…Switch for area selection, 60…Variable resistor, 61…Battery (voltage source), 62…MOSFET as a PWM switch, 70…Electrically insulating layer, 80…Mounting surface, 82…Unused area (unused space) between the light source mounting area and the light source control section, IC1, IC2…Integrated circuit, GP…Ground plane, GW…Ground line, VA…Through electrode (via, through-hole).

Claims

1. A light source device, characterized in that, The light source device has the following features: Multiple light sources are disposed on the mounting surface of the circuit board in the light source mounting area; At least one temperature detection unit is disposed on the mounting surface outside the light source mounting area; as well as A thermal pattern having a main portion and a connecting portion, the main portion collecting heat generated by the emission of at least one of the plurality of light sources located at any position, and the connecting portion being thermally connected to a temperature detection unit and transferring heat from the main portion to the temperature detection unit. When the direction perpendicular to the mounting surface of the circuit board is defined as the up-down direction, the direction on the side of the mounting surface is defined as the up direction, and the direction opposite to the up direction is defined as the down direction, The circuit board includes a surface layer on which the plurality of light sources are mounted, and an inner layer with at least one layer disposed on the underside of the surface layer, separated by an electrically insulating film. The main part of the thermal pattern, when viewed from above, overlaps with the light source mounting area and is disposed in the inner layer.

2. The light source device according to claim 1, characterized in that, From a top-down view, the main portion of the thermal pattern has a planar shape, and this planar shape overlaps with each of the plurality of light sources. or, From a top-down view, The main part of the thermal pattern has multiple branch wires extending from the connecting part. In the relative positional relationship between the multiple branch wires and the first light source located above the multiple light sources, each branch wire overlaps with a portion or all of the first light source. For a second light source that is not located above the branch wiring and does not overlap with the branch wiring, the second light source is configured such that each of the second light sources has the same shortest distance as the branch wiring, or such that the shortest distance falls within a predetermined allowable range.

3. The light source device according to claim 2, characterized in that, In the case where the main part of the thermal pattern has the multiple branch wires... Each of the multiple branch wirings has a straight or curved shape when viewed from above.

4. The light source device according to claim 2, characterized in that, The light source mounting area has a rectangular shape when viewed from above. The plurality of light sources are arranged in a matrix in the light source mounting area. The plurality of light sources configured in the matrix shape can be represented by an m-row, n-column matrix, where m is an integer of 4 or higher and n is an integer of 2 or higher. In the matrix, when viewed from above, all or part of the linear branch wiring overlaps with the first light source, which is arranged in a matrix of rows where m is a multiple of 2.

5. The light source device according to claim 1, characterized in that, The light source mounting area is divided into multiple rectangular segments in a manner corresponding to the local dimming drive of the multiple light sources. The temperature detection unit is disposed on the outer side of a predetermined end of each of the segmented regions. At least one end of the connecting portion of the thermal pattern on the side of the temperature detection portion is thermally connected to the temperature detection portion.

6. The light source device according to claim 1, characterized in that, The grounding of each of the plurality of light sources includes a ground plane with a thicker wiring width, and ground wires branching from the ground plane with a narrower wiring width than the ground plane. The ground plane is not located around the main part of the thermal pattern, but rather at a position within the light source mounting area away from the main part of the thermal pattern. or, It is located outside the area where the light source is installed.

7. The light source device according to claim 1, characterized in that, The cathode electrode of the LED, which serves as the light source, is disposed on the underside of each light source as a surface pattern disposed on the surface layer.

8. The light source device according to claim 2, characterized in that, From a top-down view, The pattern thickness in the branch wiring, which is the main part of the thermal pattern, is set to be thinner than the width of each of the plurality of light sources in the direction corresponding to the thickness of the branch wiring.

9. The light source device according to claim 1, characterized in that, On the mounting surface of the circuit board, in addition to the light source mounting area, a light source control unit for controlling the driving of the plurality of light sources is also provided. Furthermore, one or more temperature detection units are provided in the empty area between the light source installation area and the light source control unit.

10. The light source device according to claim 1, characterized in that, As the circuit substrate, a multilayer FR-4 substrate is used, which is capable of forming conductive through-parts that penetrate each layer.

11. A display device, characterized in that, The display device has: The light source device according to any one of claims 1 to 10; and A display unit that uses the light emitted by the light source device to display images.

12. A method for installing a light source device, characterized in that, The installation method of this light source device includes the following steps: Multiple light sources are set in the light source mounting area on the mounting surface of the circuit board; At least one temperature detection unit is provided on the mounting surface outside the light source mounting area; and A thermal pattern is provided, comprising a main portion and a connecting portion. The main portion collects heat generated by the emission of light from at least one of the plurality of light sources located at arbitrary positions. The connecting portion is thermally connected to the temperature detection unit and transfers the heat from the main portion to the temperature detection unit. The direction perpendicular to the mounting surface of the circuit board is defined as the up-down direction, the direction on the side of the mounting surface is defined as the up direction, and the direction opposite to the up direction is defined as the down direction. In the case where the circuit board includes a surface layer on which the plurality of light sources are mounted, and an inner layer disposed on the underside of the surface layer with an electrically insulating film in between, In the step of setting the thermal pattern, the main part of the thermal pattern is disposed in the inner layer in a way that overlaps with the light source mounting area when viewed from above.

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