JP2009087538A - Light source unit, lighting device using it, and display device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make unevenness in the vicinity of a boundary between regions less noticeable. <P>SOLUTION: An LED unit 15 comprises a substrate 18, a large number of LEDs 19 installed on the substrate 18, and light-controllable light-control lighting circuits 20 for lighting the LEDs 19. The substrate 18 is separated corresponding to a plurality of areas 22 formed by dividing an area where all LEDs 19 are disposed, and the LEDs 19 are grouped corresponding to respective areas 22 and substrates 18. The grouped LEDs 19 are respectively lit by the light-control lighting circuits 20 different from each other. The LED 19 near the boundary of one of the areas 22 among the LED 19 groups is so formed that the center axis of the light irradiated from the LED 19 is tilted to an adjacent area 22 side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light source unit, an illumination device using the same, and a display device using the same.

  Since the liquid crystal display device uses a non-self-luminous liquid crystal panel as a display panel, a backlight is required as an external light source. In general, a cold cathode tube, which is a discharge tube, is used as the light source of the backlight. However, in recent years, it has been proposed to use an LED (Light Emitting Diode) for the purpose of improving color reproducibility.

As an example of a backlight using an LED as a light source, one described in Patent Document 1 is known. This type of backlight is roughly composed of a box-shaped case having an open surface on the liquid crystal panel side, a substrate housed in the case, and a large number of LEDs installed on the substrate. Here, since the LEDs are point light sources, the LEDs are arranged in a grid, for example, on the surface of the substrate so that the luminance distribution of the entire backlight is uniform.
JP 2002-311412 A

  By the way, in a large-screen liquid crystal display device, the number of LEDs to be used is enormous, so if all LEDs are lit by a single lighting circuit, an expensive lighting circuit is required. There are problems such as. Therefore, it is conceivable to divide the substrate into a plurality of areas, group the LED groups corresponding to each area, and turn on the LED groups belonging to each group by different lighting circuits.

  However, for example, when there is a bias in the temperature distribution of the substrate or case, there is a risk that differences in the brightness and chromaticity of the LED groups in each region may occur due to the temperature difference between the regions. In order to cope with this, a light receiving element is provided corresponding to each region so that the luminance and chromaticity of the LED group of each group are detected, and the LED group of each group is detected based on a signal from each light receiving element. It is conceivable that each lighting circuit has a dimming function so as to control luminance and chromaticity.

  However, even if dimming is performed by the feedback control described above, there may be a slight difference in luminance and chromaticity between the LED groups between adjacent regions, and it is difficult to completely eliminate the difference. Met. In addition, there is a concern that unevenness near the boundary between adjacent regions is noticeable due to a difference in luminance and chromaticity of each LED group.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to make the unevenness in the vicinity of the boundary between regions less noticeable.

  The light source unit of the present invention lights a light source group belonging to each area by grouping a plurality of light sources arranged in a predetermined plane and associating these light source groups with a plurality of areas set in the plane. In the light source group, the light source existing near the boundary between the regions is inclined toward the adjacent region side with respect to the light source emitted from the light source.

  If it does in this way, the light source group grouped corresponding to each area | region in a surface will be lighted by each corresponding lighting circuit. At this time, a difference may arise in the light emission state of the light source group of each group. However, in the present invention, the light source existing near the boundary of each region in the light source group is inclined to the adjacent region side with respect to the central axis of the light emitted from the light source. The overlapping range with the irradiation area by the light source group of the group can be increased. Thereby, the nonuniformity in the vicinity of the boundary of each region can be blurred.

The following configuration is preferable as an embodiment of the present invention.
(1) The light source is a point-like light emitting element. Thus, when a point light emitting element is used as the light source, the number of light sources to be used is likely to increase compared to the case where a linear light source is used, which is particularly effective.

(2) In the light source group, the light source arranged facing the boundary line of each region is inclined to the adjacent region side with the central axis. Thereby, the nonuniformity produced near the boundary can be more effectively blurred.

(3) The light sources that exist in the vicinity of the boundaries of the regions and are lit by different lighting circuits are arranged such that the central axes are inclined toward the partner region. Thereby, since the overlapping range of the irradiation area | region by the light source groups of an adjacent group can be expanded more, the nonuniformity which arises near a boundary can be blurred more effectively.

(4) The inclination angle of the central axis in each light source that is near the boundary of each region and is lit by different lighting circuits is set to be substantially the same. Thereby, since the overlapping range of the irradiation area | region by the light source groups of an adjacent group can be made symmetrical on both sides of a boundary line, the nonuniformity which arises near a boundary can be blurred more effectively.

(5) It is assumed that each light source is installed on a substrate, and a light source mounting surface on the substrate is formed with an inclined mounting surface on which a light source existing near the boundary of each region can be mounted in an inclined posture. Thereby, the central axis of light in the light source can be tilted without changing the structure of the light source itself.

(6) A light source existing near the boundary of each region includes a light emitter that emits light and a lens that is disposed on the irradiation side with respect to the light emitter. Suppose that the axis is tilted. Thus, the central axis of the light in the light source can be tilted by making the shape of the lens asymmetric.

(7) A light source existing near the boundary of each region includes a light emitter that emits light, and a reflector that is disposed on the opposite side of the light emitter from the irradiation side and reflects light. It is assumed that the central axis is inclined because the body has an asymmetric shape. Thus, the central axis of the light in the light source can be inclined by making the shape of the reflector asymmetrical.

(8) Each region is set to divide the surface into a lattice shape, and the light source existing near the boundary forming the lattice shape between the regions is the region side where the central axis of the light emitted from the light source is adjacent. To lean to. Thereby, when the boundary of each region is in a lattice shape, unevenness in the vicinity of the boundary is easily noticeable, which is particularly effective.

(9) The lighting circuit includes a light receiving element that receives light emitted from the light source, and a light source so that the light emission state of the light source group belonging to each group is uniform between the groups based on a signal from the light receiving element. Dimming function to drive the group. Accordingly, a signal is output from the light receiving element to the lighting circuit based on the light emission state of the light source group. Based on this signal, each lighting circuit controls each light source group to make the light emission state uniform among the groups. . Therefore, it is possible to suppress the occurrence of unevenness near the boundary.

(10) A plurality of light receiving elements are provided corresponding to each group. Thereby, the light emission state of each light source group is individually detectable with the light receiving element provided for every group.

(11) The lighting circuit sequentially emits the light source groups belonging to each group, detects the light emission amount of each light source group by the light receiving element, and the detected value is a distance between the light receiving element and the light source group that has emitted light. The light source group is controlled based on the signal corrected according to the above. Thereby, compared with the case where the light receiving element is arrange | positioned for every group, the number of light receiving elements can be reduced and cost reduction can be aimed at.

(12) It is assumed that the light receiving element is attached to an optical member arranged to face the irradiation side with respect to each light source. Thereby, the light emission state of the light source group can be favorably detected by the light receiving element attached to the optical member.

  According to the present invention, unevenness in the vicinity of the boundary between adjacent regions can be made inconspicuous.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the LED unit 15 used for the backlight 12 of the liquid crystal display device 10 is illustrated. In the following, the upper side shown in FIG. 1 is the front side, and the lower side is the back side.

  First, an overview of the entire liquid crystal display device 10 will be described. As shown in FIG. 1, the liquid crystal display device 10 includes a liquid crystal panel 11 having a horizontally long shape (substantially rectangular shape) and a backlight 12 that is an external light source, and these include a display area of the liquid crystal display device 10. Is integrally held by a bezel 13 or the like formed in a frame shape surrounding the frame. Among these, the liquid crystal panel 11 is bonded to a pair of transparent (translucent) glass substrates 11a with a predetermined gap therebetween, and the optical characteristics change with voltage application between the glass substrates 11a. The liquid crystal 11b which is a substance to be sealed is enclosed. One glass substrate 11a has switching elements (for example, TFTs) connected to mutually orthogonal source lines and gate lines, and the other glass substrate 11a has R, G, B pixel electrodes in a matrix. Is provided. Further, polarizing plates 11c are respectively attached to the outer surfaces of the glass substrates 11a.

  Next, the backlight 12 will be described. The backlight 12 roughly includes a rectangular case 14 having an upper surface (the liquid crystal panel 11 side) opened, an LED unit 15 disposed in the case 14, and an opening side of the case 14. A plurality of attached optical members 16 are included.

  The case 14 is made of metal and has a configuration in which the side portion 14b is raised from the periphery of the bottom portion 14a having a substantially rectangular shape. The side portion 14b is connected to the bottom portion 14a with an obtuse angle of inclination, and the case 14 has a shape in which the opening widens toward the opening side. The optical members 16 are stacked on each other and placed on a receiving portion 14c provided at the opening of the case 14, and are held by a frame 17 attached to the case 14 from the front side. . The frame 17 is made of metal and is formed in a frame shape surrounding the display area of the liquid crystal display device 10.

  Each optical member 16 is laminated in the order of a diffusion plate, a diffusion sheet, a lens sheet, and a brightness enhancement sheet from the lower side (back side) shown in FIG. 1 and is held in a state of being sandwiched between the case 14 and the frame 17. It is like that. The light emitted from each LED 19 passes through each optical member 16, thereby being converted into a planar shape and being efficiently irradiated to the liquid crystal panel 11.

  Next, the LED unit 15 will be described in detail. The LED unit 15 includes a substrate 18 accommodated in the case 14, LEDs 19 that are a large number of light sources installed on the substrate 18, and a dimming lighting circuit 20 that lights the LEDs 19 and can be dimmed. .

  On the surface of the substrate 18 (the surface on the liquid crystal panel 11 side), as shown in FIGS. 1 and 2, a large number of LEDs 19 are arranged in the short side direction and the long side direction (vertical direction and horizontal direction) of the liquid crystal panel 11 and the case 14. ) And arranged in a grid (matrix, grid). The intervals between the LEDs 19 are set at substantially equal intervals, and the surface density of the LEDs 19 with respect to the surface of the substrate 18 is substantially uniform. Conductive paths (not shown) connected to the connection terminals of the LEDs 19 are arranged on the surface of the substrate 18 in a predetermined pattern. In addition, a plurality of support portions 21 for supporting the optical member 16 are provided at a position off the mounting position of the LED 19 on the surface of the substrate 18. The support portion 21 is a columnar body having a circular cross section that protrudes toward the optical member 16 and has a tapered shape. The intervals between the support portions 21 are set to be approximately equal.

  The LED 19 is a light-emitting element having a dot shape, and generally includes a light-emitting unit incorporating a chip (semiconductor element) (not shown) that is a light-emitting body, and a connection terminal derived from the light-emitting unit. In the light emitting section, three types of chips of R (red light emission), G (green light emission), and B (blue light emission) are provided, and three pairs of connection terminals are provided corresponding to each chip. The LED 19 emits light from three chips having different emission colors, so that the emission color is white as a whole. Further, three conductive paths of the substrate 18 corresponding to each connection terminal pair are routed.

  As shown by the broken line in FIG. 3, the irradiation area of the light from the LED 19 spreads in a substantially cone shape having a predetermined angle range with the chip as the apex, and a cross section when cut along a plane orthogonal to the irradiation direction. It is set to be almost circular. A central axis A (shown by a one-dot chain line in FIG. 3) passing through the center of the region irradiated with light from the LED 19 is vertical (optical member 16 or liquid crystal) if the LED mounting surface 18a of the substrate 18 is a horizontal surface. It is set to face in a direction perpendicular to the surface direction of the panel 11. The light distribution in the LED 19 has the highest light intensity in the direction that coincides with the central axis A, and the angle range from the central axis A increases as it goes from the central axis A to the end side (broken line) of the irradiation region. The light intensity tends to decrease gradually. Further, the axis line of the LED 19 and the central axis A of the irradiated light substantially coincide with each other.

  As shown in FIG. 2, the above-described substrate 18 is separated from each other in correspondence with a plurality of regions 22 that divide the bottom portion 14 a (arrangement region of all LEDs 19) of the case 14. Then, the LED 19 group mounted on each substrate 18 corresponding to each region 22 is grouped, and the grouped LED 19 group is lit by different (independent) dimming lighting circuits 20. It is like that. Each substrate 18 corresponding to each region 22 is formed in a horizontally long rectangular shape so as to divide the bottom portion 14a of the case 14 into a lattice shape substantially evenly, and a boundary line 23 between the regions 22 is defined by the case 14. The bottom portion 14a extends in the vertical and horizontal directions and has a lattice shape (indicated by a two-dot chain line in FIGS. 2 and 4). In the present embodiment, the bottom portion 14a of the case 14 is divided into nine regions 22 (substrate 18) in total of three vertically and three horizontally.

  The dimming / lighting circuit 20 is configured as follows. As shown in FIG. 5, the dimming lighting circuit 20 includes a power source 24 connected to one end side of the LED 19 group connected in series with each other, a transistor 25 connected to the other end side of the LED 19 group, and a transistor 25 A drive circuit 26 connected, a light reception signal processing circuit 27 connected to the drive circuit 26, and a light receiving element 28 connected to the light reception signal processing circuit 27 are provided.

  When light emitted from the LEDs 19 in the corresponding region 22 is detected by the light receiving element 28, a signal is output from the light receiving element 28 to the light receiving signal processing circuit 27, and the signal processed by the light receiving signal processing circuit 27 is sent to the drive circuit 26. Is output. The luminance and chromaticity of the LED 19 group can be controlled by adjusting the amount of current supplied to the LED 19 by the drive circuit 26 based on the input signal.

  Specifically, there are the following two methods for controlling the brightness and chromaticity of each LED 19 group to be uniform. First, the light receiving element 28 is configured to have a filter that decomposes received white light into R, G, and B. Then, the LED 19 group emits white light, and the light is detected by the light receiving element 28 having the above-described configuration, and the R, G, B light emitting elements in the LED 19 group are detected based on the light receiving amounts of R, G, B. By adjusting the amount of current to be supplied by the drive circuit 26, the luminance and chromaticity of the LED 19 group are controlled, and thereby the luminance and chromaticity between the LED 19 groups are made uniform.

  Second, the R, G, and B light emitting elements in the LED group 19 are sequentially turned on for each color, and light of each color is sequentially detected by the broadband light receiving element 28. The drive circuit 26 adjusts the amount of current supplied to the R, G, and B light emitting elements in the LED 19 group based on the received light amounts of R, G, and B, so that the brightness of the LED 19 group and By controlling the chromaticity, the luminance and chromaticity between the LED groups 19 are made uniform. In addition, the light receiving element 28 is attached to the surface of the optical member 16 facing the LED 19 in the light member (diffusion plate) disposed opposite to the LED 19 and the irradiation side (the side opposite to the case 14). One is provided corresponding to 22 and is installed at a substantially central position of each region 22 (indicated by a one-dot chain line in FIG. 2).

  In the group of LEDs 19 grouped as described above, the LEDs 19 existing in the vicinity of the boundary of each region 22 are inclined toward the adjacent region 22 side with the central axis A of the irradiated light. Specifically, the LED mounting surface 18a of the substrate 18 and the portion of the LED 19 group where the LED 19 that does not face the boundary line 23 between adjacent regions 22 is mounted is almost the same as the bottom 14a of the case 14 and the optical member 16. In contrast to the parallel horizontal plane 29, an inclined mounting surface 30 that is inclined with respect to the horizontal plane 29 is formed in a portion where the LED 19 facing the boundary line 23 between adjacent regions 22 is mounted. Therefore, the central axis A of light in the LED 19 mounted on the inclined mounting surface 30 is inclined relative to the central axis A of light in the LED 19 mounted on the horizontal plane 29.

  The inclined mounting surface 30 is formed in a portion facing the adjacent substrate 18 in the peripheral portion of each substrate 18, that is, a portion facing the boundary line 23 between the adjacent regions 22, and is on the horizontal plane 29 side (adjacent From the side opposite to the region 22 to be performed) to the edge side (the adjacent region 22 side). The inclined mounting surface 30 is formed over the entire periphery of the portion of the periphery of the substrate 18 facing the boundary line 23, and is formed as an inclined surface continuous along the short side direction or the long side direction of the substrate 18, The LEDs 19 mounted there, that is, the LEDs 19 facing the boundary line 23 are all inclined with the central axis A of the light inclined. Accordingly, in each LED 19 group mounted on each substrate 18, each LED 19 facing the boundary line 23 is inclined toward the region 22 side where the central axes A of light are adjacent to each other.

  Since the inclination angles of the inclined mounting surfaces 30 are set to be substantially the same, the inclination angles of the central axis A of the light of each LED 19 mounted thereon are also substantially the same. The light central axis A of each LED 19 facing the boundary line 23 intersects the light central axis A of the LED 19 facing the boundary line 23 in the LED 19 group of the adjacent group. The crossing positions of the central axes A of the LEDs 19 that are mounted on the inclined mounting surfaces 30 and are adjacent to each other are positioned between the optical member 16 and the substrate 18 (center in FIG. 3) in the vertical direction and in the horizontal direction. Is substantially coincident with the boundary line 23. The position where the central axis A of each LED 19 mounted on each inclined mounting surface 30 intersects the lower surface of the optical member 16 closest to the LED 19 (the surface facing the LED 19) is relative to the group to which the LED 19 belongs. The LED 19 group belonging to the adjacent group is set to enter the irradiation region side.

  The LEDs 19 facing the boundary line 23 in the LED 19 group in each region 22 will be described in detail with reference to the four regions 22 shown in FIG. In the following, in order to distinguish each region 22 and its associated substrate 18, LED 19 and inclined mounting surface 30, the suffix A is added to the reference to the upper left region shown in FIG. 4, and the reference to the lower left region in FIG. In the case of subscript B, subscript C is added to the reference numeral for the upper right region in the figure, subscript D is added to the reference numeral for the lower right region in the figure, and the reference characters are subscripted if they are collectively referred to without distinction. It shall not be attached. Regarding the boundary line 23, the subscript AB is added to the code of the boundary line between the regions 22A and 22B, the subscript AC is added to the code of the boundary line between the regions 22A and 22C, and the boundary line between the region 22C and the region 22D. In the case where the suffix CD is added to the code, the suffix BD is added to the code of the boundary line between the region 22B and the region 22D, and they are collectively referred to without distinction, the suffix is not added to the code. Moreover, the arrow line shown in FIG. 4 represents the inclination direction of each LED19.

  In the upper left substrate 18A, the inclined mounting surface 30A facing the boundary line 23AB is formed over the entire length side portion of the substrate 18A, and the LED 19A mounted here has the central axis A of the irradiated light all. The posture is inclined toward the region 22B. On the other hand, the inclined mounting surface 30A facing the boundary line 23AC of the substrate 18A is formed on the short side portion of the substrate 18A except for the mounting portion of the LED 19A (at the corner position) facing both the boundary line 23AB and the boundary line 23AC. Then, the LED 19A mounted here is in a posture in which the central axis A of the irradiated light is inclined toward the region 22C side.

  The inclined mounting surface 30B facing the boundary line 23BD in the upper left substrate 18B is formed over the entire short side portion of the substrate 18B, and the LEDs 19B mounted on the inclined mounting surface 30B all have a central axis A of the irradiated light. Is inclined to the region 22D side. On the other hand, the inclined mounting surface 30B facing the boundary line 23AB of the substrate 18B is formed on the long side portion of the substrate 18B except for the mounting portion of the LED 19B (at the corner position) facing both the boundary line 23AB and the boundary line 23BD. The LED 19B mounted here is in a posture in which the central axis A of the irradiated light is inclined toward the region 22A.

  The inclined mounting surface 30C facing the boundary line 23AC in the upper left substrate 18C is formed over the entire short side portion of the substrate 18C, and the LEDs 19C mounted here all have a central axis A of the irradiated light. Is inclined to the region 22A side. On the other hand, the inclined mounting surface 30C facing the boundary line 23CD of the substrate 18C is formed on the long side portion of the substrate 18C except for the mounting portion of the LED 19C (at the corner position) facing both the boundary line 23AC and the boundary line 23CD. The LED 19C mounted here is in a posture in which the central axis A of the irradiated light is inclined toward the region 22D side.

  In the upper left substrate 18D, the inclined mounting surface 30D facing the boundary line 23CD is formed over the entire length of the substrate 18D, and the LED 19D mounted here has a central axis A of the light to be irradiated. The posture is inclined toward the region 22C. On the other hand, the inclined mounting surface 30D facing the boundary line 23BD of the substrate 18D is formed on the short side portion of the substrate 18D except for the mounting portion of the LED 19D (at the corner position) facing both the boundary line 23BD and the boundary line 23CD. The LED 19D mounted here is in a posture in which the central axis A of the irradiated light is inclined toward the region 22B side.

  As described above, the four LEDs 19 arranged at the corner positions of the respective substrates 18 and facing the two boundary lines 23 are inclined toward the region 22 side where the central axis A of the light is adjacent in the counterclockwise direction. ing. In addition, by changing the inclined mounting surface 30, it is possible to set the four LEDs 19 facing the two boundary lines 23 to be inclined to the adjacent region 22 side in the clockwise direction.

  This embodiment has the structure as described above, and the operation thereof will be described subsequently. In order to display an image on the liquid crystal display device 10, each LED 19 group is turned on by the corresponding dimming lighting circuit 20, and an external circuit is connected to the display drive circuit (source wiring, gate wiring, etc.) of the liquid crystal panel 11. Signals necessary for display are supplied from.

  The light emitted from each LED 19 is irradiated to the liquid crystal panel 11 in a state of being converted into uniform planar light in the process of sequentially passing through each optical member 16. At this time, since the liquid crystal 11b in the liquid crystal panel 11 changes its alignment state as a signal is applied to each wiring and a voltage (electric field) is applied, the light passing through the liquid crystal 11b is accompanied accordingly. The polarization state is changed, so that a predetermined image is displayed on the liquid crystal panel 11.

  By the way, depending on the usage environment of the liquid crystal display device 10, for example, the temperature distribution of the substrate 18 and the case 14 of the backlight 12 may be biased, and if that happens, a temperature difference occurs between the regions 22 (each substrate 18). Due to this, there is a possibility that a difference occurs in the average luminance and average chromaticity of the LEDs 19 in each region 22.

  However, in the dimming / lighting circuit 20, as shown in FIG. 5, the light receiving element 28 arranged corresponding to each region 22 detects the luminance and chromaticity of each LED 19 group, and the light receiving signal processing circuit 27 It is possible to process the signal from the light receiving element 28 and output the processed signal to the drive circuit 26, and adjust the amount of current supplied to the LED 19 group based on the signal input by the drive circuit 26. In this way, the dimming and lighting circuit 20 individually controls the LED 19 group of each group to adjust the light emission state of the LED 19 group, thereby eliminating the brightness and chromaticity disparity between the LED 19 groups of each group as much as possible. Like to do.

  However, even if feedback control is performed as described above, the luminance and chromaticity of the LEDs 19 in each group, that is, the light emission state, for various reasons such as variations in the sensitivity of the light receiving elements 28 arranged in each region 22. A slight inequality may occur, and it is difficult to completely eliminate it. Further, there is a concern that unevenness is noticeable, such as uneven brightness (lightness / darkness unevenness) or uneven color near the boundary between adjacent regions 22 due to the difference in brightness and chromaticity of each LED 19 group. .

  However, in this embodiment, as shown in FIGS. 3 and 4, the LED 19 near the boundary of each region 22 in the group of grouped LEDs 19 is adjacent to the central axis A of the light irradiated by the inclined mounting surface 30. The posture is inclined toward the region 22 side. Specifically, the LEDs 19 facing each boundary line 23 between the regions 22 and facing (adjacent) each other are inclined with the central axis A of the light toward the partner region 22 side. Therefore, regarding the overlapping range of the irradiation region by the LED 19 whose central axis A is inclined and the irradiation region by the LED 19 group belonging to the adjacent group, each LED 19 facing the boundary line 23 is assumed to be another LED 19 (boundary line). Compared with the case where the central axis A of light coincides with the vertical direction in the same manner as the LED 19 which does not face 23), the central axis A of the light in the LED 19 can be expanded by an amount of inclination.

  As described above, since the overlapping range of the irradiation regions of the LEDs 19 belonging to the adjacent groups is expanded, even if a difference in the light emission state occurs between the LEDs 19 groups, the adjacent regions 22 are adjacent in the vicinity of the boundary. The change in the irradiation state of light can be made gradual, and unevenness near the boundary can be blurred. As a result, unevenness in the vicinity of the boundary between the adjacent regions 22 can be made inconspicuous, so that the display quality of the liquid crystal display device 10 can be improved.

  As described above, according to the present embodiment, for the LEDs 19 existing in the vicinity of the boundary of each region 22 in the group of grouped LEDs 19, the central axis A of the light emitted from the LED 19 is inclined toward the adjacent region 22 side. Therefore, the overlapping range of the irradiation area by the LED 19 and the irradiation area by the LED 19 group of the adjacent group can be increased, and thus unevenness generated near the boundary can be made inconspicuous.

  Further, in order to eliminate the luminance unevenness, it is conceivable to increase the distance between the liquid crystal panel 11 and the LED 19 group or increase the number and types of the optical members 16, but according to the present embodiment, this is necessary. Absent. In other words, according to the present embodiment, the distance between the liquid crystal panel 11 and the LED 19 group can be shortened, and the backlight 12 and the liquid crystal display device 10 can be thinned (downsized). In addition, the number and types of the optical members 16 can be reduced and the cost can be reduced.

  In addition, the LED 19 that is a point light emitting element as the light source is particularly effective because the number of LEDs 19 to be used tends to increase as compared with the case where a linear light source is used as the light source. .

  In addition, in the LED 19 group, the LED 19 arranged facing the boundary line 23 of each region 22 has its central axis A tilted toward the adjacent region 22 side, so that unevenness that occurs near the boundary is made more effective. Can be blurred.

  Further, each LED 19 that is present in the vicinity of the boundary of each region 22 and is lit by the dimming lighting circuit 20 that is different from each other has its central axis A tilted toward the other region 22 side. The overlapping range of the irradiation areas by each other can be expanded, and the unevenness generated near the boundary can be more effectively blurred.

  In addition, since the inclination angle of the central axis A of the LEDs 19 that are present in the vicinity of the boundaries of the regions 22 and are lit by the dimming lighting circuits 20 that are different from each other is set to be substantially the same, the irradiation regions of the adjacent groups of LEDs 19 Can be made symmetric with respect to the boundary line 23, and unevenness generated in the vicinity of the boundary can be more effectively blurred.

  In addition, each LED 19 is installed on the substrate 18, and the LED mounting surface 18 a on the substrate 18 is formed with an inclined mounting surface 30 on which the LED 19 existing near the boundary of each region 22 can be mounted in an inclined posture. Therefore, the central axis A of the light in the LED 19 can be tilted without changing the structure of the LED 19 itself. Since only one type of LED 19 is installed on each substrate 18, it is not necessary to distinguish the LED 19 when installing the LED 19 on the substrate 18, and the effect of facilitating the work can be obtained.

  In addition, each area 22 is set to divide the arrangement area of all the LEDs 19 into a grid shape, and if the boundary between the areas 22 has a grid shape, unevenness near the boundary is easily noticeable, but near the boundary. This is particularly effective because the LED 19 existing in the above is lit by the dimming lighting circuit 20 of the adjacent group.

  The dimming / lighting circuit 20 includes a light receiving element 28 that receives light emitted from the LEDs 19, and the light emission states of the LEDs 19 belonging to each group are made uniform among the groups based on a signal from the light receiving element 28. Since the LED 19 group has a dimming function to drive the LED 19 group, each LED 19 group is controlled based on a signal output from the light receiving element 28 based on the light emission state of each LED 19 group. It is possible to make the light emission state uniform in this case, and to suppress the occurrence of unevenness in the vicinity of the boundary.

  Further, since a plurality of light receiving elements 28 are provided corresponding to each group, the light emitting state of each LED 19 group can be individually detected by the light receiving elements 28 provided for each group.

  In addition, since the light receiving element 28 is attached to the optical member 16 disposed facing the irradiation side with respect to each LED 19, the light emission state of the LED 19 group can be detected well.

<Embodiment 2>
A second embodiment of the present invention will be described with reference to FIG. In this Embodiment 2, what changed the structure about LED31 which faces the boundary line 23 is shown. In the second embodiment, redundant description of the same structure, operation, and effects as those in the first embodiment will be omitted.

  As shown in FIG. 6, the light emitting portions of the LEDs 19 and 31 are provided with lenses 19 a and 31 a that transmit light emitted from a chip (not shown) and direct the light. The lenses 19a and 31a are arranged on the upper side of the chip, that is, on the irradiation side, and are formed in a substantially hemispherical shape (dome shape) surrounding (covering) the chip from above.

  Among the LEDs 19 and 31 group, the lens 19a in each LED 19 that does not face the boundary line 23 has a symmetrical shape, and the central axis A of the irradiated light is vertical when the LED 19 is placed on a horizontal surface. It is set to match. On the other hand, the lens 31a in each LED 31 arranged facing the boundary line 23 has an asymmetric shape, and the central axis A of the irradiated light is vertical when the LED 31 is placed on a horizontal surface. It is set to be inclined with respect to.

  On the other hand, the entire area of the LED mounting surface 18a ′ of the substrate 18 ′ on which the LEDs 19 and 31 are installed is a horizontal plane 29 ′. Each LED 31 facing the boundary line 23 is mounted with the direction of the lens 31a aligned so that the central axis A of the light is inclined toward the adjacent region 22 side.

  As described above, by arranging the LED 31 in which the central axis A of the irradiated light is inclined by making the shape of the lens 31a an asymmetrical shape, the LEDs 31 and 31 of the adjacent groups are arranged near the boundary. The overlapping range between the irradiation areas can be expanded.

<Embodiment 3>
A third embodiment of the present invention will be described with reference to FIG. The third embodiment shows another example in which the structure of the LED 32 facing the boundary line 23 is changed. In the third embodiment, the description of the same structure, operation and effect as in the first embodiment will be omitted.

  As shown in FIG. 7, the light emitting portions of the LEDs 19 and 32 are disposed below the chips 19b and 32a, that is, on the side opposite to the irradiation side (lens side) and direct the light toward the irradiation side. Reflectors 19c and 32b for reflection are provided. The reflectors 19c and 32b are formed in a substantially hemispherical shape with the most concave portions where the chips 19b and 32a are disposed.

  The reflector 19c in each LED 19 which does not face the boundary line 23 among the LEDs 19 and 32 group has a symmetrical shape, and the central axis A of the irradiated light is vertical when the LED 19 is installed on a horizontal surface. Is set to match. On the other hand, the reflector 32b in each LED 32 arranged facing the boundary line 23 has an asymmetric shape, and the central axis A of the irradiated light is vertical when the LED 32 is placed on a horizontal surface. It is set to be inclined with respect to the direction.

  On the other hand, the entire area of the LED mounting surface 18a ′ of the substrate 18 ′ on which the LEDs 19 and 32 are installed is a horizontal plane 29 ′. Each LED 32 facing the boundary line 23 is mounted in a state where the orientation of the reflector 32b is aligned so that the central axis A of the light is inclined toward the adjacent region 22 side.

  As described above, by arranging the LED 32 in which the central axis A of the irradiated light is inclined by making the shape of the reflector 32a asymmetrical, the LEDs 19 and 32 of the adjacent groups are arranged near the boundary. The overlapping range of the irradiation areas can be expanded.

<Embodiment 4>
A fourth embodiment of the present invention will be described with reference to FIG. In the second embodiment, a case where the number of light receiving elements 41 is changed to one is illustrated.

  As shown in FIG. 8, the dimming / lighting circuit 40 includes a light receiving element 41 capable of receiving light emitted from the LEDs 19 belonging to each group, a light receiving signal processing circuit 42 connected to the light receiving element 41, and a light receiving signal process. The driving circuit 43 is connected to the circuit 42 and connected to the LED 19 group belonging to each group.

  In the present embodiment, only one light receiving element 41 is prepared for each of the nine groups of LEDs 19, and therefore the distance between the light receiving element 41 and the LEDs 19 belonging to each group varies depending on the group. There is. Due to this difference in distance, even if the light emission state of each LED 19 group is the same, the amount of light received by the light receiving element 41 may be different for each group.

  Therefore, the light receiving signal processing circuit 42 can correct the difference in distance between the light receiving element 41 and each LED 19 group. The received light signal processing circuit 42 includes a light receiving circuit 44, a CPU 45, a distance correction coefficient storage unit 46, and a correction amount storage unit 47. The light receiving circuit 44 outputs a signal corresponding to the signal input from the light receiving element 41 to the CPU 45. The distance correction coefficient storage unit 46 outputs a distance correction coefficient corresponding to the distance between the light receiving element 41 and the LED 19 group of each group to the CPU 45. The distance correction coefficient is set for each group of LEDs 19 corresponding to the above difference in distance. By multiplying the distance correction coefficient by the actually received light amount detected by the light receiving element 41, the distance correction coefficient is assigned to each LED 19 group. On the other hand, it is set so that a pseudo light receiving amount as detected by a virtual light receiving element arranged at an equidistant position can be obtained. Thereby, the shift | offset | difference of the light reception amount by the disparity of the distance of the light receiving element 41 and LED19 group can be corrected.

  Based on the signal from the light receiving circuit 44 and the distance correction coefficient from the distance correction coefficient storage unit 46, the CPU 45 calculates the pseudo received light quantity excluding the distance difference and brings the pseudo received light quantity to the target value. The amount of correction necessary for the calculation is calculated. Here, the target value is a value at which the luminance and chromaticity between the LEDs 19 in each group become uniform. The correction amount storage unit 47 stores the correction amount output from the CPU 45 in association with each group. Each correction amount is updated each time a usage time of the liquid crystal display device 10 elapses a predetermined time (for example, 100 hours).

  The correction amount corresponding to each group is updated as follows. The LEDs 19 belonging to each group are caused to emit light sequentially, and the light receiving element 41 receives light from each LED 19 group each time. According to the method described above, the pseudo received light amount and the correction amount in the LED 19 group are sequentially calculated based on the obtained actual received light amount, and the obtained correction amount is stored in the correction amount storage unit 47 in association with the group. Let

  Then, the drive circuit 43 that turns on the LEDs 19 belonging to each group adjusts the amount of current supplied to each LED 19 based on each correction amount output from the light reception signal processing circuit 42. Thereby, the brightness | luminance and chromaticity between each LED19 group can be equalize | homogenized now.

  As described above, according to the present embodiment, the number of light receiving elements 41 can be reduced and the cost can be reduced as compared with the case where the light receiving elements 28 are individually installed for each group as in the first embodiment. be able to.

  Note that the number of light receiving elements 41 is not limited to one, and a plurality of light receiving elements 41 may be provided in a range not exceeding the total number of groups (nine in this embodiment). In this case, when the LEDs 19 belonging to each group are sequentially turned on, the light receiving elements 41 can simultaneously receive light. Thereby, improvement of measurement accuracy can be aimed at.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) Regarding the LED 19-1A facing both the two boundary lines 23-1 in the LED 19-1 group, as shown in FIG. (In FIG. 9, the inclined mounting surface 30-1A on which the LED 19-1A facing both of the two boundary lines 23-1 is mounted has a diagonally opposite region 22-1 side. (The figure shows a setting with a slope that slopes to the right). In this way, the overlapping range of the irradiation area of the LED 19-1A and the irradiation area of the LED 19-1 group of the three adjacent areas 22-1 can be expanded.

  (2) In the above-described embodiment, only the LED facing the boundary line is illustrated by tilting the central axis of the light. However, as shown in FIG. 10, the LED 19-2A facing the boundary line 23-2 With respect to the LED 19-2B (the LED 19-2B in the second column from the boundary line 23-2) arranged on the opposite side of the boundary line 23-2 with respect to the LED 19-2A, the light central axis A is adjacent. It may be set to tilt toward the region 22-2 side. In that case, a difference may be made between the inclination angle of the central axis A of the LED 19-2A facing the boundary line 23-2 and the inclination angle of the central axis A of the LED 19-2B in the second row (see FIG. 10, the inclined mounting surfaces 30-2A and 30-2B are two-step inclined surfaces, and the inclined mounting surface 30-2B corresponding to the second row has a smaller inclination angle).

  (3) In addition to the above (2), the central axis of the light of the LEDs in the third and subsequent columns from the boundary line may be inclined toward the adjacent region.

  (4) In the above-described embodiment, the LED facing the boundary line is shown by tilting the central axis of the light. However, as shown in FIG. 11, the LED 19- in the second column from the boundary line 23-4. With respect to 4A, the central axis A of the light may be inclined, and the central axis A may be set not to be inclined with respect to the third and subsequent LEDs 19-4B and the LED 19-4C facing the boundary line 23-4 (in FIG. 11, the LED is mounted). A setting is shown in which the inclined mounting surface 30-4 is formed in the portion corresponding to the second row of the surface 18a-4, and the other portion is the horizontal surface 29-4). In addition to the LEDs in the second row, the third and subsequent LEDs may be inclined in the same manner as described above.

  (5) In the above-described embodiment, all of the LEDs facing the boundary line are shown with the light central axis inclined, but as shown in FIG. 12, the LED 19-5A with the central axis inclined and the central axis The LED 19-5B that is not inclined may be alternately arranged (in FIG. 12, the inclined mounting surface 30-5 and the horizontal surface 29-5 are alternately arranged at the end of the substrate 18-5. To do). At this time, the LED 19-5A with the central axis inclined and the LED 19-5B with no inclination may be set to face each other across the boundary line 23-5.

  (6) In the above-described embodiment, the LED groups facing each other across the boundary line are set so that the central axes are inclined to the other region side. However, as shown in FIG. 22-5A and 22-5B are set such that only the LED 19-5A in one region 22-5A is inclined with respect to the central axis and the LED 19-5B in the other region 22-5B is set not to be inclined. Included in the invention (FIG. 13 illustrates the case where the inclined mounting surface 30-5 is provided only on one of the substrates 18-5A).

  (7) In the above-described embodiment, each LED is arranged in a lattice shape along the vertical direction and the horizontal direction of the LED mounting surface of the substrate. However, as shown in FIG. Are arranged obliquely with respect to the vertical direction and the horizontal direction of the LED mounting surface 18a-7 of the substrate 18-7.

  (8) In the above (1) to (7), as the means for tilting the central axis of the light in the LED, only the tilted mounting surface is illustrated, but the shape of the LED lens and reflector as in the second and third embodiments. The central axis of the light may be tilted by changing.

  (9) The inclination angle of the central axis of light in the LED can be arbitrarily changed. For example, the setting may be such that the intersection position between the central axis of the LED and the lower surface of the optical member does not enter the irradiation region of the LED group belonging to the adjacent group, or the setting matches the boundary line.

  (10) Further, the intersection position between the central axes of the LEDs adjacent to each other may be set so as not to be between the optical member and the LED in the vertical direction (for example, a setting in the optical member).

  (11) Further, when the central axes of the LEDs adjacent to each other are inclined, it is not necessary to set the same inclination angle to each other, and the present invention includes those in which the intersection positions of the central axes do not coincide with the boundary line. It is.

  (12) In the above-described embodiment, each region is set to divide the LED mounting surface of the substrate into a grid shape. However, as shown in FIG. 15, each region 22-12 includes all LEDs. The setting area may be divided along the vertical direction.

  (13) Moreover, as shown in FIG. 16, each area 22-13 may be set to divide the arrangement area of all LEDs along the horizontal direction.

  (14) The individual shape of each region can be arbitrarily changed, and can be set to a square, a rhombus, a triangle, or the like, for example. Further, the number of areas can be arbitrarily changed.

  (15) In the above-described embodiment, the light receiving element is attached to the optical member. However, as shown in FIG. 17, the wire W is bridged between the adjacent support portions 21-15, and the wire W Alternatively, the light receiving element 28-15 may be attached. In addition, the arrangement position of the light receiving element can be arbitrarily changed. For example, the light receiving element may be attached to the inner peripheral surface of the side portion of the backlight case. Also, the number of light receiving elements per region can be arbitrarily changed.

  (16) In the above-described embodiment, an example in which an LED including three types of R, G, and B chips is used is exemplified. For example, a single chip (specifically, a blue light emitting chip or an ultraviolet light emitting chip) is used. ), And a phosphor that emits white light as a whole may be used. In addition, an LED that emits white light as a whole can be used.

  (17) Furthermore, the present invention includes those in which three types of R, G and B single-color LEDs are used. Moreover, it is also possible to use LED which emits monochromatic light other than white or R, G, B.

  (18) In the above-described embodiment, the case where the lighting circuit for lighting the LED group is a dimming lighting circuit having a dimming function is exemplified, but there is also a case where a lighting circuit having no dimming function is used. It is included in the present invention. The lighting circuit in that case has a circuit configuration in which the light receiving element 29 and the light receiving signal processing circuit 28 shown in FIG. 4 are omitted.

  (19) In the above-described embodiment, the case where an LED is used as a point-like light emitting element is exemplified. However, for example, other types of point-like light emitting elements such as EL (Electro Luminescence) and a semiconductor laser are used. Also good.

  (20) In the above-described embodiment, a point light emitting element is exemplified as the light source. However, a linear light source such as a discharge tube (a cold cathode tube or a hot cathode tube) may be used.

  (21) The present invention can also be applied to a liquid crystal display device using switching elements other than TFTs. Besides the liquid crystal display device for color display, the present invention can be applied to a liquid crystal display device for monochrome display.

  (22) Besides the liquid crystal display device, the present invention can be applied to other types of display devices using a backlight other than the liquid crystal.

Sectional drawing of the liquid crystal display device which concerns on Embodiment 1 of this invention. Plan view of LED unit LED unit enlarged cross-sectional view Main part enlarged plan view of LED unit Block diagram of dimming lighting circuit The principal part expanded sectional view of the LED unit which concerns on Embodiment 2 of this invention. The principal part expanded sectional view of the LED unit which concerns on Embodiment 3 of this invention. The block diagram of the light control lighting circuit which concerns on Embodiment 4 of this invention The principal part enlarged plan view of the LED unit which concerns on other embodiment (1). The principal part expanded sectional view of the LED unit which concerns on other embodiment (2). The principal part expanded sectional view of the LED unit which concerns on other embodiment (4). The principal part enlarged plan view of the LED unit which concerns on other embodiment (5). The principal part enlarged plan view of the LED unit which concerns on other embodiment (6). The principal part enlarged plan view of the LED unit which concerns on other embodiment (7). The top view of the LED unit which concerns on other embodiment (12). The top view of the LED unit which concerns on other embodiment (13) The principal part expanded sectional view of the LED unit which concerns on other embodiment (15).

Explanation of symbols

10. Liquid crystal display device (display device)
11 ... Liquid crystal panel (display panel)
12 ... Backlight (lighting device)
14 ... Case 15 ... LED unit (light source unit)
16 ... Optical member 18a ... LED mounting surface (light source mounting surface)
19, 31, 32 ... LED (light source)
DESCRIPTION OF SYMBOLS 20 ... Light control lighting circuit 22 ... Area | region 23 ... Boundary line 28 ... Light receiving element 30 ... Inclined mounting surface 31a ... Lens 32a ... Chip (light-emitting body)
31b ... reflector A ... central axis

Claims (15)

A number of light sources arranged in a predetermined plane;
A lighting circuit for lighting these light source groups belonging to each region by grouping these light source groups in association with a plurality of regions set in the plane,
In the light source group, a light source unit that is located near the boundary between the regions is a light source unit in which a central axis of light emitted from the light source is inclined toward an adjacent region. The light source unit according to claim 1, wherein the light source is a point-like light emitting element. The light source unit according to claim 2, wherein in the light source group, the light sources arranged facing the boundary lines of the respective regions are inclined toward the adjacent region side in the central axis. 4. The light source unit according to claim 2, wherein each of the light sources that exist in the vicinity of the boundary between the regions and are lit by the different lighting circuits has their central axes inclined toward each other. 5. The light source unit according to claim 4, wherein an inclination angle of the central axis is set to be substantially the same in each of the light sources that are present in the vicinity of the boundary between the regions and are lit by the lighting circuits different from each other. 2. The light source is mounted on the substrate, and the light source mounting surface of the substrate is formed with an inclined mounting surface on which the light source existing in the vicinity of the boundary between the regions can be mounted in an inclined posture. The light source unit according to claim 5. The light source existing in the vicinity of the boundary of each region includes a light emitting body that emits light, and a lens disposed on the irradiation side with respect to the light emitting body, and the lens has an asymmetric shape, The light source unit according to claim 1, wherein the central axis is inclined. The light source located in the vicinity of the boundary of each region includes a light emitter that emits light, and a reflector that is disposed on the side opposite to the irradiation side with respect to the light emitter and reflects light. The light source unit according to claim 1, wherein the central axis is inclined by making the body asymmetrical. Each of the regions is set to divide the surface into a lattice shape, and the light source existing in the vicinity of the boundary forming the lattice shape between the regions is the region side where the central axis of light emitted from the light source is adjacent The light source unit according to claim 1, wherein the light source unit is inclined to the right. The lighting circuit includes a light receiving element that receives light emitted from the light source, and the light emission state of the light source group belonging to each group is made uniform among the groups based on a signal from the light receiving element. The light source unit according to claim 1, which has a dimming function for driving the light source group. The light source unit according to claim 10, wherein a plurality of the light receiving elements are provided corresponding to each group. The lighting circuit sequentially emits light sources belonging to each group, detects a light emission amount of each light source group by the light receiving element, and detects a detection value between the light receiving element and the light source group that emits light. The light source unit according to claim 10, wherein the light source group is controlled based on a signal corrected according to the distance. The light source unit according to any one of claims 10 to 12, wherein the light receiving element is attached to an optical member arranged to face the irradiation side with respect to each light source. An illumination device comprising: the light source unit according to any one of claims 1 to 13; and a case for housing the light source unit. A display device comprising the lighting device according to claim 14 and a display panel.

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