JP2011095759A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which can be manufactured inexpensively and has a liquid crystal panel uniformly irradiated with light. <P>SOLUTION: The liquid crystal display device includes the liquid crystal panel and an illuminating device which is used as a backlight irradiating the liquid crystal panel with light and includes a plurality of LED (Light Emitting Diode) packages each of which comprises an LED and a lens, and which has a large area by congregation of the LED packages on a plane. In the liquid crystal display device, on a plane substantially parallel to the liquid crystal panel, a direction substantially parallel to a direction in which scanning lines extend is denoted as a column direction, and a direction substantially orthogonal to the column direction is denoted as a row direction, and a bottom of the backlight having the congregating LED packages is divided into two or more regions, and a means for driving LEDs individually or in respect of each of the plurality of regions is provided, and the lens in each LED package has different widths between the directions. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device such as a TV or a monitor, and more particularly to a liquid crystal display device using an illumination device that uniformly irradiates a liquid crystal panel with light.

  As an LED package including a light emitting diode (referred to as an LED) and a lens, there are those disclosed in Documents 1 and 2.

  The content of Document 1 is “a lens provided with a main body, the main body including a central axis extending along the length direction of the main body, a first surface for coupling to a light source, and a sawtooth lens portion. A sawtooth lens portion that refracts the light emitted from the light source so that most of the light emitted from the sawtooth lens portion is generally perpendicular to the central axis of the body; A funnel-shaped lens unit connected to the lens unit, wherein the light emitted from the light source is such that most of the light emitted from the funnel-shaped lens unit is generally perpendicular to the central axis of the body. And a lens having a funnel-shaped lens portion to be reflected.

  Document 3 is a document related to a liquid crystal display device using an illumination device using an LED package composed of an LED and a lens as a backlight.

  Reference 4 is a technique for improving moving picture performance by placing a reflector between lamps in a cold-cathode lamp (CCFL) backlight, but mentions a light-emitting diode (LED) that is a point light source. Absent.

JP 2003-8068 A JP 2003-8081 A R. West, “High Brightness Direct LED Backlight for LDC-TB”, SDI 03 digest, pp1262-1265 (R. West, “High Brightness Direct LED Backlight for LCD-TV”, SID03 DIGEST, pp1262- 1265) Tee. Shiga and three others, “Adaptive Dimming Technique with Optically Isolated Lamp Groups”, S.I. Di 05 Digest, pp992-pp995 (T. Shiga, “Adaptive Dimming Technique with Optically Isolated Lamp Groups”, SID05 DIGEST, pp992 -pp995)

  FIG. 2 is a diagram for explaining the problem. An installation surface on which the LED package 2 is installed is referred to as an xy plane, and a direction perpendicular to the xy plane is referred to as a z direction. FIG. 2 is a cross-sectional view regarding the xz plane of the lens 1. The lens is rotationally symmetric about the z axis. The LED package 2 includes one LED and a lens 1, and the lens has a funnel-shaped portion (referred to as a funnel portion 100). The LED package 2 includes members (not shown) such as wiring, but is not shown for simplicity of explanation.

  The techniques described in documents 1 to 3 include a funnel portion 100 as shown in FIG. The funnel portion 100 is designed as a total internal reflection (TIR) surface. This TIR surface reflects light so that it exits the lens 1 at an angle as close to 90 degrees as possible with respect to the z-axis. The ray RAY is an example in which the light emitted from the LED is traced.

  In order to manufacture the lens 1 at low cost, it is preferable to perform injection molding. However, since the funnel portion 100 is caught when the mold is pulled out, it is difficult to mold with one mold. Therefore, the funnel portion and the lens portion below the funnel portion are separately manufactured, and then the two portions are bonded together or integrally molded using a plurality of molds. In either case, there is a problem that the manufacturing cost is high because a plurality of molds are used. In addition, when integrally molding using a plurality of molds, there is a problem that it is difficult to obtain accuracy for forming a lens shape.

  Since the above prior art does not consider the influence on the manufacturing method, there is a problem that the cost increases and the manufacturing accuracy decreases.

  An object of the present invention is to provide a liquid crystal display device using an illumination device that can be manufactured at low cost and that uniformly irradiates a liquid crystal panel with light.

  In order to solve the problem, in an illuminating apparatus having a plurality of LED packages each composed of an LED and a lens and collecting the LED packages in a planar shape to increase the area, at least four LED packages are provided. The LED package includes at least a red LED, a green LED, and a blue LED. At least two LEDs in the LED package are arranged at the center of the lens. And the two LEDs are of the same color.

  In order to solve the problem, in a lighting device having a plurality of LED packages each composed of an LED and a lens, and the LED packages are assembled in a planar shape to increase the area, the LED package has at least red color. There are at least two types of LED packages having LEDs that emit light, LEDs that emit green light, and LEDs that emit blue light, and in which the arrangement of the LEDs in the LED package is different.

  In order to solve the problem, a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, a signal wiring and a scanning wiring for applying a voltage corresponding to image data to the liquid crystal layer at a predetermined timing, As a backlight for irradiating light to the liquid crystal panel, a liquid crystal panel having a plurality of active elements connected to intersections of the signal lines and the scanning lines, and pixels driven by the active elements, an LED A liquid crystal display device having a plurality of LED packages each having a plurality of LED packages each having a large area by gathering the LED packages in a planar shape, in a plane substantially parallel to the liquid crystal panel. When the direction parallel to the direction in which the scanning wiring extends is the column direction and the direction substantially perpendicular to the column direction is the row direction, the LED package A plurality of regions that divide the bottom surface of the backlight that collects the light into two or more, and drive the LEDs individually or for each of the plurality of regions; in the LED package, the width of the lens in the column direction; And a lens having a different width in the row direction.

  In order to solve the problem, a pair of substrates, a liquid crystal layer sandwiched between the pair of substrates, a signal wiring and a scanning wiring for applying a voltage corresponding to image data to the liquid crystal layer at a predetermined timing, As a backlight for irradiating light to the liquid crystal panel, a liquid crystal panel having a plurality of active elements connected to intersections of the signal lines and the scanning lines, and pixels driven by the active elements, an LED A liquid crystal display device having a plurality of LED packages each composed of a lens and a large-area lighting device by gathering the LED packages into a planar shape, in a plane parallel to the liquid crystal panel, When the direction substantially parallel to the direction in which the scanning wiring extends is the column direction and the direction substantially perpendicular to the column direction is the row direction, the LED package The bottom surface of the assembled backlight is provided with a plurality of regions that are divided into two or more, and a means for driving the LED individually or for each of the plurality of regions, and a portion in which the width of the lens differs depending on the direction in the LED package. And a lens having the same.

  The present invention is not limited to the configurations described in the claims and the configurations disclosed in the embodiments described later. It goes without saying that various modifications can be made without departing from the technical idea of the present invention.

  The liquid crystal panel is effectively irradiated with light at a low cost.

It is a figure for demonstrating the illuminating device of Example 1 which concerns on this invention. It is a figure for demonstrating the subject solved by this invention. It is a figure for demonstrating the illuminating device of Example 1 which concerns on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 2 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 2 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 3 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 3 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 3 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 3 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 3 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 3 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 4 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 4 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 5 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 5 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 6 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 7 which concern on this invention. It is a figure for demonstrating the illuminating device and liquid crystal display device of Example 7 which concern on this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  Example 1 of the present invention will be described. FIG. 1A shows an LED package 2 composed of red, blue, and green LEDs (labeled as LEDR, LEDB, and LEDG, respectively) and a lens 1, and includes two green LEDs. Shows the case. Red and blue LEDs are placed near the center, green LEDs are placed farther from the center than red and blue, and the two green LEDs are equal in distance from the center and on a straight line passing through the center Is arranged. That is, the two LEDs are arranged at symmetrical positions with respect to the center. An installation surface on which the LED package 2 is installed is defined as an xy plane, and a direction in which light is emitted and illuminated is perpendicular to the xy plane is referred to as a z direction. FIG. 1A is a cross-sectional view regarding the xz plane. The lens is rotationally symmetric about the z axis.

  Only one LED is included in the LED package, and an LED package that emits red light, an LED package that emits blue light, and an LED package that emits green light are arranged in the lighting device to emit white light. Compared to the case of irradiation, the use of an LED package including three LEDs of red, blue, and green reduces the number of lenses, which can reduce material and reduce waste. It becomes possible.

  However, as shown in FIG. 1B, when the red, blue, and green LEDs are simply arranged one by one, the light emitted from the LEDs arranged at the center of the lens is in the xy plane. The light emitted from the two LEDs that are isotropically emitted from the lens but cannot be arranged in the center is anisotropic. This is because the LED having the lens shape at the center of the lens is designed as a point light source.

  Since the colors of the LEDs in the LED package are different, when the emission distribution from the lens is greatly different, the colors are not mixed and the colors are not uniform. In particular, with respect to LEDs arranged at both ends, the direction in which the position of the LED from the center is shifted is reversed, so the direction in which the emission distribution is biased is reversed, which is a major factor in making the color uneven. This problem can be avoided by enlarging the lens so that the three LEDs are sufficiently small relative to the lens and can be considered as a point light source. There is a problem that the thickness increases.

  By adopting the configuration as shown in FIG. 1A, this problem can be solved. By arranging the two green LEDs symmetrically with respect to the center, it is possible to compensate for changes in the distribution of the emitted light due to deviation from the center of each other, and the anisotropic emission distribution is isotropic. It is possible to improve the light emission distribution. This effect can be obtained by arranging LEDs of the same color substantially symmetrically with respect to the center of the lens. In other words, an effect cannot be obtained unless it is arranged at a strictly symmetrical position. Extremely speaking, when the xy plane is divided into two by a straight line perpendicular to the straight line connecting the LED and the center of the lens, an LED having the same color as the LED is arranged in a region different from the region where the LED is arranged. The compensation effect also works.

  Furthermore, by arranging the two green LEDs at positions farther from the center than the red and blue LEDs, the red and blue LEDs that cannot compensate for the emission distribution are brought closer to the center. This makes it easy to mix colors.

  The reason why the green LED is used to compensate for the green LED in this embodiment is that the green LED has low power efficiency, and in order to obtain sufficient luminance, it is desirable to have more LEDs than other colors. It is.

Further, by placing the center of the lens at the center between the red and blue LEDs, the distance between the center of the lens and the red and blue LEDs can be reduced. When the minimum distance at which the LEDs can be brought close is L _G , the distance between the center of the lens and the red and blue LEDs is L _G / 2. The case shown in FIG. 1 (b), the distance between the LED and the center of the end of the lens becomes (the length of half the size of the center of the LED) + L _G.

Further, although it is possible to compensate for the green LED, it is preferable to be closer to the center of the lens. A configuration in which all LEDs are brought close to the center 3 of the lens with the simplest configuration is shown in FIG. FIG. 3A shows an example of mounting an LED using a lead frame. When using a lead frame, the simplest configuration is to arrange the LEDs in a row. Further, by setting the distance between all of the LED and the minimum distance L _G, the two LED and symmetrical arrangement in the farthest distance from the center 3 of the lens, and, most LED in the LED package to the center of the lens The arrangement can be approached. The compensation effect described above is effective even when the position of the LED is deviated from an equidistant arrangement in the range of about 0.1 to 0.3 mm.

  Further, in the sense that the LED is closest to the center of the lens, it is possible to mount as shown in FIG. 3B by forming a wiring on the submount 6 using the submount 6. is there. Also in this case, the green LED is arranged at a symmetrical position with respect to the center 3 of the lens.

  Further, a configuration in which an LED with a large amount of emitted light is arranged in the center and LEDs with a small amount of emitted light are arranged on both sides is also conceivable. Alternatively, it is also conceivable that LEDs with high power efficiency are arranged in the center and two LEDs with low power efficiency are arranged on both sides. Alternatively, it is conceivable that one blue LED having a small influence on luminance is arranged in the center and two LEDs of other colors are arranged on both sides thereof. FIGS. 3C and 3D show a case where five LEDs are included in the LED package, a blue LED having a small influence on luminance is arranged in the center, and the other LEDs have the same color as the lens. The case where it arrange | positions so that it may become symmetrical about the center of is shown. In this case, by arranging a plurality of LEDs, the amount of light obtained from one package increases, so the number of LED packages can be reduced. That is, waste reduction due to material reduction and processing costs can be reduced.

  In FIG. 3, the LED of the color to be compensated is not necessarily green. However, since the efficiency of the green LED is low, it is desirable to include a plurality of LEDs in the LED package to make the LED for compensation.

  Further, regarding the arrangement of the LEDs other than the color to be compensated, the relationship between the arrangement and the color is not particularly specified. For example, in FIG. 3, the positions of red and blue LEDs may be exchanged.

  A second embodiment of the present invention will be described with reference to FIG. FIG. 4 (a) shows an LED package 2 consisting of red, blue, and green LEDs (labeled as LEDR, LEDB, and LEDG, respectively) and a lens 1, and includes two green LEDs. Shows the case. Red and blue LEDs are placed near the center, green LEDs are placed farther from the center than red and blue, and the two green LEDs are equal in distance from the center and on a straight line passing through the center Is arranged.

  An installation surface on which the LED package 2 is installed is defined as an xy plane, and a direction in which light is emitted and illuminated is perpendicular to the xy plane is referred to as a z direction. FIG. 4A is a cross-sectional view regarding the xz plane. The lens is rotationally symmetric about the z axis.

  In this embodiment, the z axis in the figure is a central axis that passes through the center of the lens and is perpendicular to the installation surface on which the LED package is installed. The lens shape is the range of most polar angles (approximately polar) when the distance from the center of the lens to the lens surface is the moving radius, and the angle from the central axis is the polar angle (POLAR ANGLE). The angle is 0 ° to 80 °), and the moving radius increases as the polar angle increases. When the polar angle is 80 ° or more, the moving radius is constant. Therefore, there is no shape in which the radius decreases as the polar angle increases.

  The lens shown in the figure is a lens that emits a lot of light at an angle of light emission larger than a polar angle of 45 °. FIG. 4B shows the relationship between the emission intensity and the emission angle. As for the emission angle, the polar angle from the central axis to the x-axis direction is a positive angle, and the negative direction of the x-axis is a negative angle. The horizontal axis is the angle of emission from the lens and the unit is degrees. The vertical axis represents the luminous flux per solid angle. The intensity increases at an emission angle of 45 ° to 80 °.

  In the first embodiment, in an LED package including red, blue, and green LEDs, a configuration in which the LED arrangement is symmetrical with respect to the center of the lens and a configuration in which the LEDs are gathered at the center of the lens are employed. The color is made uniform by making isotropic in the ground plane.

  By using the lens shown in FIG. 4A, most of the light emitted from the lens is emitted in the in-plane direction (in the direction of 45 ° to 90 ° in which the polar angle is large), and is uniformed in the surface. Therefore, it is possible to achieve further uniformity in the lighting device before light is emitted from the lighting device.

  The lens shown in FIG. 4A has a shape in which there is no region in which the moving radius decreases as the polar angle increases. Therefore, when the mold is peeled from the lens in the z direction in the injection molding process, There is no portion where the mold is caught (for example, when the moving radius is gradually reduced in a polar angle region of 60 ° to 90 °, the region is caught when the mold is pulled out). Therefore, it is not necessary to use multiple dies, and since it can be molded with a single dies, the accuracy of the dies can be increased, and the manufacturing process is simple and quick. Costs can be reduced and energy consumed for manufacturing can be reduced. In addition, due to the problem of manufacturing accuracy, an error of about several hundred μm can be made, and the radius may become smaller as the polar angle becomes larger. However, due to unevenness of about several hundred μm, a plurality of molds are used. There is no need. Therefore, when an error of several hundreds of μm is ignored, there is no need to use a plurality of molds if there is no region where the moving radius decreases as the polar angle increases.

  The reason why there is a dent in the center of the lens is as follows. In order to increase the emission angle from the polar angle 0 ° to the critical angle θc of the substance constituting the lens to the air (38 ° to 46 ° when the lens is made of ordinary resin), FIG. As shown, the normal of the lens surface (NORMAL VECTOR) is tilted in the direction where the x component of the normal vector is negative when the lens surface is at a positive position of x, and the lens surface is at the negative position of x. If there is, tilt in the direction in which the x component of the normal vector is positive. Therefore, each surface element of the lens surface where x is in a positive position moves in the z-axis direction as it advances in the x direction, and each surface element of the lens surface where x is in a negative position becomes z as it advances in the −x direction. This is to move in the axial direction. That is, the z-axis component of the tangent line in each surface element is positive.

  In the lens, a critical angle θc with respect to air of a substance constituting the lens is increased in a region in which the radius of movement increases as the polar angle increases (when the refractive index of the lens is Nm, the critical angle θc is Nm × sin (θc ) = 1, the reason why the polar angle is equal to that of FIG. 4 will be described with reference to FIG. In order to emit light emitted from the LED near the critical angle in the in-plane direction (polar angle 90 ° direction) by the lens, the normal direction of the lens surface in the critical angle direction needs to be approximately parallel to the z-axis. . In this case, the z-axis component of the tangent to the lens surface is almost zero, and the x component has a value close to 1. Therefore, the surface element on the lens surface moves in substantially parallel to the x-axis as it advances in the x-direction, so that the radius of movement increases. For the above reasons, the radius of movement increases as the polar angle increases near the critical angle.

  Furthermore, the lens shape described above in this embodiment is particularly sensitive to deviation of the LED arrangement from the lens center. Therefore, in this lens shape, the LED arrangement configuration described in Example 1 is particularly important. The reason will be described with reference to FIG.

  FIG. 5 shows an emission angle θout into the air when light is incident at an angle θin with respect to the normal of the lens surface in a lens having a refractive index of 1.5. The unit is degrees (deg) for both the horizontal and vertical axes. As can be seen from the figure, as the incident angle θin increases as the emission angle θout increases from 60 ° to 90 °, θout increases steeply. That is, this means that the differential value dθout / dθin is large, and in the region where the emission angle is larger than 60 °, the emission angle θout with respect to the deviation of the incident angle, that is, the deviation from the center of the LED. Means that it will change greatly.

  Therefore, in the case of the lens shape that emits a lot of light at the large emission angle (45 ° to 90 °) described above in the present embodiment, the emission distribution changes greatly when the LED deviates from the lens center. The LED arrangement described in the first embodiment is particularly important.

  This embodiment is a backlight for a liquid crystal display device that takes into consideration that the image quality of the liquid crystal display device is improved by driving the LED for each region and causing the region to emit light or turn it off at a certain timing. The invention relates to the invention of the lighting device.

  For each region, change the image data to increase the transmittance of the liquid crystal panel, while reducing the brightness of the corresponding region of the lighting device to reduce power consumption, increase the effective contrast, etc. Improve image quality. In addition, the moving picture quality is improved by a scroll BL system in which lighting and extinguishing are sequentially performed for each area composed of one line or a plurality of lines. In such a case, it becomes an important subject to emit light uniformly for each arbitrary region of the lighting device. That is, in the second embodiment, as much light as possible is emitted in the backlight in-plane direction and uniformized over the entire backlight surface. However, in the present exemplary embodiment, uniformity in each region is a problem. In particular, the present embodiment relates to an illumination device that realizes uniform light emission for each region.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 6A shows a configuration example of the liquid crystal display device 11, which includes a lighting device 7, a diffusion plate 8, an optical sheet 9, and a liquid crystal panel 10. The optical sheet 9 is a sheet for diffusing and condensing light, and there may be a plurality of sheets such as a diffusion sheet, BEF, and DBEF. The illumination device 7 is used as a so-called backlight of a liquid crystal display device.

  FIG. 6B shows a configuration example of the liquid crystal panel. The signal wiring driving circuit 13 drives the signal wiring 12, the scanning wiring driving circuit 15 drives the scanning wiring 14, and a thin film transistor 16 as an active element is connected to the intersection of the signal wiring and the scanning wiring. The scanning wiring controls on / off of the thin film transistor serving as a switch, and the signal wiring supplies a desired voltage to the liquid crystal of each pixel. The liquid crystal is electrically represented by a capacitor (liquid crystal capacitor 17) formed between the pixel electrode 18 connected to the thin film transistor and the counter electrode 19.

  FIG. 6C is a configuration example of the lighting device 7 in which the LED packages 2 are assembled in a planar shape to increase the area. The LED package 2 includes an LED and a lens 1. However, the LED package may include other members such as a heat radiating member, a submount, etc., but is not described for the sake of simplicity.

  The illuminating device of FIG. 6C is provided with four regions and means for driving the LED for each of the four regions. The LED packages 2 arranged in the column direction, which is substantially parallel to the direction in which the scanning wiring 14 extends, are electrically connected in series using the lead frame 4, and the LEDs are controlled using the control signals BLC 1 to 4. The control switch 21 is driven, and the LED packages 2 connected in series in each row are driven for each row.

  The LED power supply circuit 20 is a circuit that supplies power to the LEDs in each row, and generates and supplies a voltage to be supplied to each row from the power supply voltage VDH and the ground GND. When there are a plurality of LEDs included in the LED package 2, for example, when there are three red, blue, and green, the LED power supply circuit 20 supplies three voltages, and the lead frame 4 also has three for each row. It becomes a book and is connected in series for each color. There are also three LED control switches 21 in each row. When the LED control switch is controlled for each color, the control signal is also tripled. The moving image quality is improved by sequentially turning on / off the LEDs for each row and scrolling the on / off positions.

  The shape of the lens 1 constituting the LED package 2 is a lens shape in which the width of the lens in the column direction is different from the width of the lens in the row direction, and the region to which the LED package belongs is long in the column direction. In order to measure, the lens shape in the column direction is longer than the lens width in the row direction.

  As described in the second embodiment, since the lens for increasing the emission angle to make uniform makes the moving radius larger as the angle at which the light from the LED enters the lens surface increases, the direction in which the emission angle is increased. The lens width also increases. Therefore, the width of the lens in the direction in which the width of the region is large is also increased. The ratio between the width in the column direction and the row direction depends on the size and shape of the backlight and the region, but when the longer lens width is about 18 mm, the shorter lens width is 17 mm to 10 mm. In many cases.

  Various combinations of lens shapes are also conceivable. An example is shown in FIGS. In order to make the explanation easy to understand, the LED package 2 that is simultaneously driven at an arbitrary timing is surrounded by a line as a region 22. The shape of the LED packages 2 and 2 'shown reflects the lens shape. In FIG. 7, the LED package 2 is a lens having a long lens shape in a certain direction, and the LED package 2 ′ is a lens having a lens shape having substantially the same diameter in all directions.

  7A and 7B show a lens shape in which the longer the region width is, the longer the lens width is, and the longer the region width is, the light is emitted with a large emission angle.

  FIGS. 7C and 7D show a lens having a long lens shape in which a lens having a long lens shape in a certain direction and a lens having a lens shape having substantially the same diameter in all directions are included in the region. The longer region has a longer lens width. By combining a lens having a lens width different depending on the direction and a lens having an isotropic lens width, a region having an arbitrary shape can be made uniform.

  In the first embodiment, in an LED package including red, blue, and green LEDs, a configuration in which the LED arrangement is symmetrical with respect to the center of the lens and a configuration in which the LEDs are gathered at the center of the lens are employed. The color is made uniform by making isotropic in the ground plane. Also in this embodiment, it is important not only to increase the emission angle of light from the lens to achieve uniformity in the area plane, but also to achieve uniformity in consideration of LED arrangement.

  When the LED package includes only one LED, it is preferable to arrange three LED packages each having red, blue, and green LEDs close to each other, and the arrangement as shown in FIG. Good for uniform area. In the figure, LEDs 1 to 3 indicate LEDs of different colors. In this arrangement, the area 22 and the area 22 ′ have different timings for light emission in time, but if the deviation of the light emission timing is sufficiently short, the arrangement utilizing the fact that different colors between adjacent areas are also mixed. It is. In this arrangement example, the lens shape of the central LED package (LED2 in the figure) of the three LED packages that are continuous in each region may be different from the lens shape of the LED packages at both ends. The LED packages at both ends of the three LED packages are different in color from the adjacent four LED packages. Moreover, you may arrange | position in a line like FIG.8 (b).

  When a plurality of LEDs are included in one package, the following various arrangements are conceivable.

  FIG. 9A shows a case where two green LEDs and one red and blue LED are included. The longer the region, the longer the lens shape, and the LEDs are arranged along the longer region. In each LED package, the green LEDs are symmetrically arranged with respect to the center of the lens. This is an arrangement for compensating the emission distribution from the lens of the green LED light in the long direction of the region to obtain a symmetric emission distribution in order to improve the uniformity in the long direction of the region. By arranging them in a single row, it can be easily connected using a lead frame (not shown in FIG. 9).

  Similarly, FIGS. 9B to 9D are arranged to compensate for the emission distribution of the green LED light from the lens in the long direction of the region to obtain a symmetrical emission distribution. For the sake of simplicity, the direction of the arrow in the figure is the long direction of the region. FIG. 9D shows a case where five LEDs are included in one LED package.

  In FIG. 9, the LED of the color to be compensated is not necessarily green. However, since the efficiency of the green LED is low, it is desirable to include two LEDs in the LED package to make the LED to be compensated. Further, regarding the arrangement of LEDs other than the color to be compensated, the relationship between the arrangement and the color is not specified. For example, in FIG. 9, the positions of red and blue LEDs may be exchanged.

  In general, when moving picture quality is improved by the scroll BL method, the timing of scanning a scanning wiring connected to a pixel in a row and the timing of turning on or off the backlight that irradiates light to the area of the pixel are controlled. In order to do this, the LED is controlled for each row or for each of a plurality of rows. Therefore, the long direction of the region is the column direction (the direction in which the scanning wiring extends). Therefore, when the scroll BL method is used, the LED is arranged either symmetrically on a line substantially parallel to the column direction or symmetrically arranged on a line perpendicular to the column direction. desirable. In order to increase the uniformity of the longer region, the LEDs may be arranged so as to be symmetrical on a line substantially parallel to the column direction. When the lead frame is used for wiring, the lead frame is used as scanning wiring. Considering wiring in parallel, it is not necessary to bend the lead frame by arranging the LEDs symmetrically on the line perpendicular to the column direction, and it is possible to improve the yield and manufacture by simplifying the backlight manufacturing process. This is good in terms of reducing the energy required.

  In addition, especially when the distance from the LED package to the edge of the region is short because the width of the region is short and it is difficult to achieve uniformization, an arrangement that is advantageous for uniformizing the LEDs in the LED package is arranged in the direction in which the width of the region is short. It is good also as arrangement. In such a case, the arrangement of the LEDs shown in FIGS. 9A to 9C is an arrangement in which the direction of the lens is maintained and rotated by 90 °.

  In addition, although the timing of light emission differs between adjacent areas in time, an arrangement utilizing the fact that different colors between adjacent areas are mixed if the deviation of the emission timing is sufficiently short is shown. 10 (a) to (d).

  In the arrangement of FIG. 10A, the LEDs are arranged in a row in the LED package, and the positions of the two LEDs arranged in the center are reversed in the adjacent regions. By doing so, the color non-uniformity generated between the adjacent regions 22 and 22 'is improved.

  10B and 10C are arranged in an LED package including four first to fourth LEDs (LEDs 1 to 4), and the first and second LEDs of the same color remain symmetrically arranged. Thus, the third and fourth LEDs are inverted in the LED arrangement between adjacent LED packages in the area, and the LED arrangement in the LED package between the adjacent areas is made equal, thereby reducing the color non-uniformity. It has improved.

  In the arrangement of FIG. 10D, the first to third LEDs are included in the LED package, and the arrangement of the first and third LEDs in the LED package is reversed between the adjacent areas, so that The color non-uniformity has been improved.

  The relationship between the LED package and the LED arrangement as shown in FIG. 10 described above is not particularly an invention that is effective only when an area is provided and the LED is driven for each area or when the scroll BL is performed. Even in normal cases, the effect is achieved.

  Further, the relationship between the LED package and the LED arrangement as shown in FIG. 10 described above is effective even in the case of a lens shape whose diameter does not change depending on the orientation. An example is shown in FIG.

  Here, the region includes means capable of controlling individual LEDs or a set of a plurality of LEDs individually or for each set, and a region including these individual or sets is called a region. .

  For example, in FIG. 6, a portion obtained by dividing the lighting device 7 into four in the row direction so as to include a set of LED packages in which each portion is connected in series in four stages is called a region.

  The present embodiment relates to achieving uniformity in each region while improving the moving image characteristics by devising not only the LED package but also the shape of the backlight frame.

  This will be described with reference to FIGS. Consider a case where the backlight is divided into three in the row direction in order to improve the moving image performance in the scroll BL method. The case where the LEDs in the column direction are connected in series and the LEDs are controlled for each region will be described.

  FIG. 12A is a diagram of the backlight as viewed from the direction in which light is emitted (side where the liquid crystal panel is disposed). The side reflector 23 has a shape that reflects light emitted from the LED package 2 in the column direction. The shape is such that the distance between the line B1 passing through the center of the lens and parallel to the column direction and the end EDGE of the side reflector is at the midpoint between the adjacent LED packages 2 from the distance D1 at the center of the lens. The distance D2 is a larger shape. Here, the end portion EDGE of the side reflector refers to a portion where the side reflector rises from a flat portion of the frame. In addition, when the side reflector is gently raised, a portion that is 1/10 the height of the side reflector is defined as an end of the side reflector. In the figure, RAY is a simple ray tracing example. The side reflector may be a white reflector sheet attached to a shape formed by processing the iron frame 24, or may be formed by processing such as cutting or injection molding using resin as the frame material. In this case, the resin is preferably a white resin.

  Sectional views from line segments A1 to A1 'are shown in FIGS. 12 (b) and 12 (c). FIG. 12B is a diagram when the side reflector 23 has a rectangular cross section. A three-dimensional wire frame diagram in this case is shown in FIG. The cross section from A2 to A5 described in FIG. 12D corresponds to the cross section from A2 to A5 in FIG.

  FIG. 12C is a diagram in the case where the cross-section of the side reflector 23 is generally triangular or trapezoidal. A three-dimensional wire frame diagram in this case is shown in FIG. The cross section from A2 to A5 described in FIG. 12E corresponds to the cross section from A2 to A5 in FIG.

  When the cross-section of the side reflector is a rectangular cross-section shown in FIG. 12 (b), light is emitted in the in-plane direction than in the case of the triangular or trapezoidal cross-section shown in FIG. 12 (c). The effect of reflecting is great.

  The lighting device is turned on in the case of the triangular or trapezoidal cross section shown in FIG. 12 (c) as compared with the rectangular cross section shown in FIG. 12 (b). In such a case, unevenness due to the side reflector is difficult to see (or unevenness is unlikely to occur).

  The shape of the edge EDGE of the side reflector may be a triangular wave shape in which isosceles triangles are periodically repeated, or may be a shape in which an ellipse or a circular arc is periodically repeated. Examples of these shapes are shown in FIG. FIG. 13A is a case where isosceles triangles are periodically repeated, and FIG. 13B is a case where elliptical arcs are periodically repeated.

  The present embodiment relates to improving the light extraction efficiency from the LED to the lens and making it uniform.

  The refractive index of an LED varies depending on the color, but is about 2.2 to 3.8, and the refractive index of a general resin forming a lens is about 1.5. Therefore, total reflection occurs at the interface between the LED and the lens, and a part of the light emitted from the LED is confined in the LED, resulting in a loss. To solve this problem, the resin used to seal the LED has a high refractive index of about 1.6 to 2.2, and a lens is placed over the resin to extract light from the LED. Efficiency can be improved.

  This will be described with reference to FIG. FIG. 14 is a cross section of an LED package including the center of the lens. The emission direction of the backlight is the z direction, and a certain direction in the backlight surface is the x direction. Four LEDs (LEDR, LEDG, LEDB) are sealed with a high refractive index member. The high refractive index member 25 is a resin or the like including a resin or titanium oxide that is a high refractive index fine particle. Therefore, there are cases where the refractive index has a distribution inside the resin, such as when the high refractive index fine particles are not uniformly mixed. A material (medium) containing a substance having a high refractive index is used as the high refractive index member. Needless to say, a material that is not a mixture and is formed of a material having a high refractive index is also called a high refractive index member. A resin having a lens shape is attached to the outside of the high refractive index member 25. Here, the resin portion having a lens shape is referred to as a lens 1. The shape of the boundary 26 between the lens 1 and the high refractive index member 25 is a semicircle centered at the origin (the origin of the xz plane in the figure, hereinafter sometimes referred to as the center of the lens).

  Since the lens is designed with a point light source at the origin, there is a problem in that light emitted from the lens does not exit in a predetermined direction when refraction occurs at the boundary 26. As shown in FIG. 14, since the light emitted from the vicinity of the origin is hardly refracted by making the shape of the boundary 26 a semicircle, the above problem can be solved. When the lens has an isotropic shape in the backlight surface, the cross-sectional shape is a semicircle, so the three-dimensional shape of the boundary 26 is a hemispherical shape.

  However, in relation to the shape and production method of the LED package, in the region (70 to 90 degrees) where the polar angle (angle from the z-axis) is large, the shape of the boundary 26 may not be a circle. There is no problem as long as the shape of the circular arc is within an angular range in which light is controlled by utilizing it. That is, if a part of the boundary has an arc shape, the effect is obtained. Specifically, the lens is actively used within an angle range of 0 to 50 degrees polar angle. If the light emitted from the LED at an angle larger than 50 degrees is not a shape in which the boundary or the lens shape is extremely different from the circle, the light is emitted from the LED at a long distance, so that the light can be emitted far away. Further, it is desirable that the boundary surface be mirror-finished with little unevenness. This is to suppress unnecessary scattering at the interface.

  Next, a manufacturing method will be described. There are at least the following two manufacturing methods. First, when sealing an LED with a high refractive index member, the high refractive index member is injection molded, and then a separately manufactured lens is bonded, or the lens is directly injection molded onto the high refractive index member. That's how it is. When a separately manufactured lens is bonded, the refractive index of the adhesive is desirably equal to or higher than the refractive index of the lens. This is to prevent unnecessary refraction or total reflection from occurring when light is transmitted from the adhesive to the lens. Specifically, a refractive index of about 1.5 is desirable.

  The second will be described with reference to FIG. First, a lens is prepared by injection molding. When the exit surface 28 of the lens is on the interface side with air and the entrance surface 29 is on the boundary side with the high refractive index member 25, a hole 27 penetrating from the exit surface to the entrance surface is opened. After the lens is arranged on the backlight, a high refractive index member is sealed from the hole 27, and the lens entrance surface is molded as a mold.

  In the fifth embodiment, the shape of the boundary 26 between the high refractive index member 25 and the lens 1 in a cross section of the LED package including the center of the lens is a circle, thereby reducing unnecessary refraction at the boundary 26 to reduce the lens. It is possible to make the light emission distribution from the predetermined distribution. In the present embodiment, the use of the shape of the boundary 26 as a surface for controlling light will be described.

  FIG. 16 shows a cross section of the LED package including the center of the lens as in FIG. The reference numerals and the like in the figure are the same as those in FIG. The shape of the boundary 26 in the cross section is not a circle but a shape having a dent in the vicinity of x = 0. By adopting such a shape, the light incident on the lens 1 from the high refractive index member 25 is refracted at the boundary 26 and is emitted in the in-plane direction (direction where the polar angle is large 45 ° to 90 °). . By refracting this light again in the in-plane direction on the exit surface of the lens 1, more light can be emitted in the in-plane direction. In particular, by using two refracting surfaces, it is possible to efficiently emit light emitted from an LED having a limit on one refracting surface to a polar angle of about 0 ° to 45 ° in the in-plane direction. Become. Examples of the shape of the boundary 26 that exhibits such emission characteristics include the following.

  In a cross section of the LED package including the center of the lens, the boundary shape has a recess at the boundary near the center of the lens 1.

  In a cross section of the LED package including the center of the lens, the distance from the center of the lens 1 to the boundary is the inner radius, and the angle from the central axis passing through the center of the lens 1 perpendicular to the installation surface on which the LED package is installed When the is a polar angle, the boundary shape has a region in which the inner radius increases as the polar angle increases.

  In the boundary, at most polar angles, there is no region in which the inner radius decreases as the polar angle increases.

  In the boundary, the polar angle having an angle equal to the critical angle with respect to the member constituting the lens 1 of the material constituting the high refractive index member 25 is included in the region where the inner moving diameter increases as the polar angle increases. The specific critical angle is about 38 to 60 degrees.

  Specifically, for example, the boundary and lens shape in a cross section of the LED package including the center of the lens may be an elliptical arc having a major axis in the x-axis direction and a minor axis in the z-axis direction.

  In the sixth embodiment, the shape of the boundary 26 is also related to use as a surface for controlling light, and in particular, light is emitted in the in-plane direction to achieve uniformity. In the seventh embodiment, a technique will be described in which uniformization is performed for each arbitrary region of the lighting device, and a lens shape is reduced to reduce waste by reducing material.

  FIG. 17 shows a cross section of the LED package including the center of the lens as in FIG. The reference numerals and the like in the figure are the same as those in FIG. The shape of the boundary 26 in the cross section is an elliptical shape, characterized in that the z-axis direction is the major axis and the x-axis direction is the minor axis. Such a shape irradiates more light in a narrower area than the LED package described in the sixth embodiment, but is an advantageous configuration for uniformizing each predetermined area. In addition, the lens shape is reduced, and there is an effect of reducing waste by reducing the material. Since most of the light emitted from the LED and refracted at the boundary is irradiated to a narrow range (a range of polar angle from 0 to 45 °) of the lens, the lens shape can be made within the narrow range. Therefore, the lens shape can be reduced.

  Further, in making uniform for each arbitrary region of the lighting device, a configuration as shown in FIG. 18 is conceivable particularly when making uniform in the column direction in order to perform the scroll BL method. The x direction is a direction parallel to the column direction, and the y direction is a direction parallel to the row direction. The cross section of the LED package including the center of the lens shown in FIG. 18A is a cross section included in the xz plane. The cross section of the LED package including the center of the lens shown in FIG. 18B is a cross section included in the yz plane. The shape of the LED package is anisotropic. The x direction (column direction) is the lens 1 and the boundary shape 26 that emit a lot of light in the in-plane direction. In the y direction (column direction), the lens 1 and the boundary shape 26 emit light uniformly at all angles (polar angles). By adopting such a shape, it becomes easy to make uniform in the column direction. FIG. 18A shows a shape in which a concave portion is present at the boundary 26 near the center of the lens 1. For example, the shape of the boundary 26 and the lens 1 has a long axis in the x-axis direction and is in the y-axis direction. There may be a spheroid with a short axis and the x axis as the rotation axis.

  DESCRIPTION OF SYMBOLS 1 ... Lens, 2 ... LED package, 3 ... Lens center, 4 ... Lead frame, 5 ... Wire, 6 ... Submount, 7 ... Illuminating device, 8 ... Diffuser, 9 ... Optical sheet, 10 ... Liquid crystal panel, 11 DESCRIPTION OF SYMBOLS ... Liquid crystal display device, 12 ... Signal wiring, 13 ... Signal wiring drive circuit, 14 ... Scanning wiring, 15 ... Scanning wiring drive circuit, 16 ... Thin-film transistor (TFT), 17 ... Liquid crystal capacity, 18 ... Pixel electrode, 19 ... Counter electrode 20 ... LED power supply circuit, 21 ... LED control switch, 22 ... region, 100 ... funnel part, 101 ... package base, 23 ... side reflector, 24 ... frame, 25 ... high refractive index member, 26 ... high refractive index member And lens boundary, 27... Lens hole, 28... Exit surface, 29.

Claims (30)

A pair of substrates; a liquid crystal layer sandwiched between the pair of substrates; a signal wiring and a scanning wiring for applying a voltage corresponding to image data to the liquid crystal layer at a predetermined timing; and the signal wiring and the scanning wiring A liquid crystal panel having a plurality of active elements connected to intersections with the pixels and pixels driven by the active elements;
A liquid crystal display device having a plurality of LED packages each composed of an LED and a lens as a backlight for irradiating light to the liquid crystal panel, and a large-area lighting device that is a collection of the LED packages in a planar shape In
In a plane substantially parallel to the liquid crystal panel, when a direction substantially parallel to the direction in which the scanning wiring extends in the liquid crystal panel is a column direction, and a direction substantially perpendicular to the column direction is a row direction,
A plurality of regions that divide the bottom surface of the backlight in which the LED packages are assembled into two or more, and a means for driving the LEDs individually or for each of the plurality of regions;
An LED package comprising: a lens having a lens width in the column direction and a lens having a different width in the row direction. A pair of substrates; a liquid crystal layer sandwiched between the pair of substrates; a signal wiring and a scanning wiring for applying a voltage corresponding to image data to the liquid crystal layer at a predetermined timing; and the signal wiring and the scanning wiring A liquid crystal panel having a plurality of active elements connected to intersections with the pixels and pixels driven by the active elements;
A liquid crystal display device having a plurality of LED packages each composed of an LED and a lens as a backlight for irradiating light to the liquid crystal panel, and a large-area lighting device that is a collection of the LED packages in a planar shape In
In a plane parallel to the liquid crystal panel, when a direction substantially parallel to the direction in which the scanning wiring extends in the liquid crystal panel is a column direction and a direction substantially perpendicular to the column direction is a row direction,
A plurality of regions that divide the bottom surface of the backlight in which the LED packages are assembled into two or more, and a means for driving the LEDs individually or for each of the plurality of regions;
An LED package, comprising: a lens having a portion in which the width of the lens differs depending on the orientation. In the LED package, when the region to which the LED package belongs is long in the column direction, the lens has a lens whose width in the column direction is longer than the width of the lens in the row direction,
3. The liquid crystal display device according to claim 1, wherein when the region to which the LED package belongs is long in the row direction, the liquid crystal display device includes a lens in which the width of the lens in the column direction is shorter than the width of the lens in the row direction. .   3. The liquid crystal display device according to claim 1, wherein the LED package includes a lens having a portion in which the width of the lens varies depending on the orientation, and a lens having a constant lens diameter regardless of the orientation. 4. A plurality of regions that divide the bottom surface of the backlight that collects the LED packages into at least two parts in the row direction, and a means for driving the LEDs individually or for each of the plurality of regions;
3. The liquid crystal display device according to claim 1, wherein the LED package includes a lens in which a width of a lens in a column direction is longer than a width of a lens in a row direction.   6. The liquid crystal display according to claim 1, further comprising means for electrically connecting a plurality of LED packages existing in a column direction in series and driving the LEDs for each of the plurality of connected LED packages. apparatus.   6. The liquid crystal display device according to claim 1, further comprising means for arranging the LED packages in a matrix on the bottom surface of the backlight and driving the LEDs for each row or for each of a plurality of rows.   8. The liquid crystal display device according to claim 1, wherein the LED package includes at least an LED that emits red light, an LED that emits green light, and an LED that emits blue light. 9. The LED package has at least four LEDs, and has at least a red LED, a green LED, and a blue LED.
The at least two LEDs in the LED package are arranged at symmetrical positions with respect to the center of the lens, and the two LEDs have the same color. A liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 9, wherein in the LED package, all the LEDs are arranged in one row.   10. The liquid crystal according to claim 9, wherein in the LED package, at least one pair of LEDs arranged at a symmetrical position with respect to the center of the lens is two LEDs that are farthest from the center. Display device.   12. The liquid crystal display device according to claim 11, wherein the number of LEDs included in the LED package is four, and two LEDs that are farthest from the center are green LEDs.   The number of LEDs included in the LED package is five, one LED is arranged at the center of the lens, and the other LEDs are set in two groups of two, and each group is related to the center of the lens. The LED is arranged symmetrically, the color of the LED constituting each group is made equal for each group, and one of the two groups is a group of green LEDs. The liquid crystal display device described.   14. The LED package according to claim 9, wherein at least one pair of LEDs arranged at a symmetrical position with respect to the center of the lens is arranged on a line substantially parallel to the column direction. A liquid crystal display device according to 1.   15. The liquid crystal display device according to claim 14, wherein in the LED package, the LEDs arranged at symmetrical positions with respect to the center of the lens are arranged on a line substantially parallel to the column direction.   The liquid crystal according to any one of claims 1 to 15, wherein the distance from the installation surface on which the LED package is installed to the lens surface is a lens shape in which a region longer than the center of the lens exists. Display device.   In the lens, when the distance from the center of the lens to the lens surface is a moving radius and the angle from the central axis passing through the center of the lens is perpendicular to the installation surface on which the LED package is installed, the central axis 16. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a lens shape in which a moving radius increases as the polar angle increases in a lens cross section including   18. The liquid crystal according to claim 17, wherein the lens has a lens shape in which a region in which a moving radius increases as a polar angle increases in a cross section including at least a central axis substantially parallel to the column direction. Display device. The LED package has at least a red LED, a green LED and a blue LED,
The liquid crystal display device according to claim 1, wherein there are at least two types of LED packages having different LED arrangements in the LED package.   The LED package has a plurality of LEDs, and in the LED package, all the LEDs are arranged in a line and arranged on a line substantially perpendicular to a direction in which the scanning wiring extends. The liquid crystal display device according to claim 1.   10. The liquid crystal display according to claim 9, wherein in the LED package, at least one pair of LEDs arranged in a symmetrical position with respect to the center of the lens is arranged on a line substantially perpendicular to the column direction. apparatus.   10. The liquid crystal display device according to claim 9, wherein in the LED package, all the LEDs are arranged in one row and arranged on a line substantially parallel to the column direction.   10. The liquid crystal display device according to claim 8, wherein in the LED package, all the LEDs are arranged in one row and arranged on a line substantially perpendicular to the column direction.   A plurality of regions that divide the bottom surface of the backlight that collects the LED packages into two or more in the row direction are provided, and a means for driving the LED for each region and a part between the region and the region adjacent to the region 3. The liquid crystal display device according to claim 1, further comprising a side reflector that reflects light from the LED package to a region including the LED package. 4.   When the side reflector rises from the flat part of the frame on which the LED package is disposed as the end of the side reflector, a straight line that passes through the center of the lens and is parallel to the column direction, and side reflection The distance between each point when the perpendicular line is drawn from each point on the end of the plate and the straight line is greater at the midpoint between adjacent LED packages than at the center of the lens. The liquid crystal display device according to claim 24, wherein the liquid crystal display device has a shape as follows.   26. The liquid crystal display device according to claim 25, wherein the shape of the end portion of the side reflector includes a plurality of isosceles triangles.   26. The liquid crystal display device according to claim 25, wherein the shape of the end portion of the side reflector includes a plurality of elliptical arcs.   26. The liquid crystal display device according to claim 25, wherein the shape of the end portion of the side reflector includes a plurality of arcs.   25. The liquid crystal display device according to claim 24, wherein a cross-sectional shape of the side reflector has a narrowed portion. 25. The liquid crystal display device according to claim 24, wherein a cross-sectional shape of the side reflector is narrower at a position closer to the diffuser than at the frame side.

Images