JP4684073B2 - LED backlight device and image display device - Google Patents

Description

  The present invention relates to an LED backlight device and an image display device, and more specifically, an LED backlight device using an LED (light emitting diode) as an element for illuminating a light modulation element such as a liquid crystal panel, and the LED backlight. The present invention relates to an image display apparatus that includes an apparatus and displays an image.

  An LED backlight has attracted attention as a backlight for illuminating a light modulation element such as a liquid crystal panel from the back. The LED backlight has a configuration in which white LEDs are arranged to emit white illumination light, and LEDs of three colors of R (red), G (green), and B (blue) are arranged. There is a configuration in which three colors of light are mixed to form white light. Here, for the white LED, a method of obtaining white by combining RGB phosphors with a short wavelength LED chip, a method of obtaining white by combining yellow phosphors with a blue LED chip, or a three-color LED chip of RGB A method of obtaining white as mixed light, a method of obtaining white as mixed light of two-color LED chips serving as complementary colors, and the like can be employed.

  Such a backlight using an LED has several characteristic advantages over a backlight using a fluorescent tube such as a conventional cold cathode tube (CCFL). For example, a fluorescent tube that has been conventionally used as a backlight has a problem that a high voltage is required for lighting, and that the life of the fluorescent tube is shortened if lighting and extinguishing of the fluorescent tube are repeated in a complicated manner. . In addition, since the fluorescent tube is usually formed of a glass material, there is a problem that the degree of freedom of shape is limited as a backlight light source.

  In contrast, backlights using LEDs can be driven at a lower voltage than fluorescent tubes, and have superior performance such as low power consumption and long life. In addition, a backlight using three-color LEDs is characterized in that white light is obtained from wavelengths close to the three primary colors of light, so that the degree of color freedom is increased compared to conventional cold cathode tubes. In particular, the color reproducibility can be greatly expanded so that the color reproducibility exceeding 100% compared to the NTSC standard can be realized and the white point (white color) can be freely adjusted. Become.

  As an LED backlight, for example, there is a light guide plate type in which a light guide plate is disposed on the back side of a liquid crystal panel and a plurality of LEDs are arranged in an array at the end of the light guide plate. In this case, the illumination light emitted from the LED array illuminates the liquid crystal panel via the light guide plate. In addition, optical sheets such as a diffusion plate and a prism sheet are appropriately disposed between the light guide plate and the liquid crystal panel in order to give light distribution characteristics and luminance component characteristics to the illumination light.

  In contrast to the light guide plate system as described above, a direct type LED backlight in which LEDs are arranged directly under the back side of a liquid crystal panel is also provided. Also in the direct type LED backlight, the optical sheets as described above are appropriately disposed between the LED and the liquid crystal panel. The direct type LED backlight has advantages such as higher light utilization efficiency and lighter weight than the light guide plate method. Regarding the light utilization efficiency, the light utilization efficiency of a light guide plate type LED backlight is about 50%, for example, whereas the light utilization efficiency of a direct type LED backlight is as high as about 75%. .

In general, a display device using a liquid crystal panel is required to have a high level of screen brightness. For example, in a liquid crystal television device, the luminance level of the screen is required to be at least 450 cd / m ^2, and in order to satisfy such a requirement, a direct type LED backlight having a high light utilization efficiency is basically advantageous. It can be said that.

  However, in a direct type LED backlight, it is common to arrange LEDs in a grid pattern, and in such a configuration, there arises a problem that the amount of light at the outermost peripheral portion is insufficient.

  In order to solve such problems, in the conventional LED backlight, the light quantity in the outermost peripheral portion is compensated by inserting a diffusion sheet between the LED and the liquid crystal, or the liquid crystal panel to which the LED backlight is applied It is a little wider than the display panel.

  FIG. 10 is a schematic top view of a conventional LED backlight, and shows the LED backlight disclosed in Patent Document 1. The backlight units shown in FIGS. 10A and 10B are arranged in a matrix on the substrate 101 housed in the housing 105 so that a desired number of single-color or multiple-color LEDs 102 maintain a predetermined degree of uniformity. Is done. Light from the LED 102 of the substrate 101 is diffused by one or a plurality of diffusion plates 104 and irradiated from behind the display surface portion to keep the display surface portion at a predetermined uniformity. Further, a polarizing sheet is provided on the diffusion plate 104 as necessary to emit light appropriately with respect to the angle direction in which the display surface portion is viewed.

  As another LED arrangement example described in Patent Document 1, in order to improve the uniformity, the number of LEDs 102 arranged at the end of the substrate 101 is increased as shown in FIG. In this arrangement example, the LEDs 102 are arranged uniformly near the center of the substrate 101, and the number of LEDs 102 arranged at the end of the substrate 101 is increased.

Further, in Patent Document 1, as shown in FIG. 10D, the uniformity between the LED 102 attached to the end portion of the substrate 101 and the inner side surface of the housing 105 is made narrower than the arrangement pitch of the LEDs 102, thereby improving the uniformity. Examples of improved LED placement are also described. In this arrangement example, the LEDs 102 are uniformly arranged on the substrate 101 at an arrangement pitch of x _{1 in} the horizontal direction and y _{1 in} the vertical direction. Then, the arrangement pitch (lateral direction x ₀ , vertical direction y ₀ ) between the outermost end portion of the substrate 101 (inner side surface of the housing 105) and the LED 102 attached to the end portion of the substrate 101 is made narrower than the arrangement pitch of the LEDs 102. Deploy. That is, the LEDs 102 are arranged so that x ₀ <x ₁ and y ₀ <y ₁ .

Further, in Patent Document 1, a relatively large current is supplied to the LEDs 102 near the edge of the substrate 101 to increase the brightness compared to the LEDs 102 in the central portion of the substrate, in contrast to the LEDs 102 arranged uniformly on the substrate 101. Thus, an LED backlight unit that keeps the display surface portion at a predetermined uniformity as a whole has also been proposed.
JP 2003-331604 A

  As described above, in the conventional direct type LED backlight device, there is a limit to the diffusion of the LED light by the diffusion plate, and unless a certain number of LEDs are arranged, the luminance of the outer peripheral portion of the screen becomes insufficient. In particular, when a large-screen liquid crystal panel is used, the number of LEDs used is also required, which increases the cost. Further, by providing the LED backlight in a range that is slightly larger than the display panel, the luminance deficiency at the outer peripheral portion of the screen is improved, but this involves an increase in size, cost, and power consumption.

  Insufficient luminance at the outer periphery of the screen can be improved by the technique described in Patent Document 1, but in the example shown in FIG. 10B, not only the number of LEDs required to obtain the same luminance is increased. Since the LEDs are not arranged at a uniform pitch, the manufacture becomes difficult. In the example shown in FIG. 10C, it is not only necessary to increase the number of LEDs arranged in a row at the substrate end compared to the inside of the substrate, but also the current flowing through the LED at the substrate end flows through the substrate. The power consumption is excessively increased. Further, in the example shown in FIG. 10D, the distance between the LED at the end of the substrate and the housing is narrowed on the assumption that the current flowing through the LED at the end of the substrate is equal to the current flowing through the inside of the substrate. There is no change in increasing the number of LEDs per unit area in order to compensate for insufficient luminance in the outer peripheral portion.

  In Patent Document 1, there is no description or suggestion that a current smaller than that of the LED at the center of the substrate is supplied to the LED near the edge of the substrate in order to compensate for insufficient luminance at the outer peripheral portion of the screen. Therefore, in the technique described in Patent Document 1, not only is the number of LEDs required to obtain the same luminance increased, but when a current equal to or larger than the central portion of the substrate is passed through the LEDs at the edge of the substrate, As a result, an extra increase in power consumption is required.

  The present invention has been made in view of the above circumstances, and without increasing the size and cost of the image display device to be mounted, while suppressing an increase in the number of installed LEDs and an excessive increase in power consumption, It is an object of the present invention to provide an LED backlight device capable of solving the luminance deficiency in the outer peripheral portion of the screen and an image display device including the LED backlight device.

In order to solve the above-mentioned problem, a first technical means is an LED backlight device configured to illuminate an object to be illuminated from the back with light emitted from the LEDs, and further arranges a plurality of LEDs, and the outer periphery thereof. a plurality of auxiliary LED for assisting amount in the portion arranged a row, the auxiliary LED is driven at a lower current than the LED, which was characterized in that to emit light with a plurality of directions of directional It is.

According to a second technical means, in the first technical means, the auxiliary LED has an LED chip, and the LED chip includes an insulator or a cavity part of a junction portion in the N-type semiconductor and the P-type semiconductor. The light-emitting device is characterized in that light is emitted at least at both end portions sandwiching the portion formed of the insulator or the cavity.

A third technical means is characterized in that, in the first technical means, the auxiliary LED has an elongated cross-sectional shape, and a central portion in a longitudinal direction is shielded by a reflecting member that reflects emitted light to the inside. It is a thing.

According to a fourth technical means, in any one of the first to third technical means, the plurality of LEDs are arranged on lattice points of a lattice having a predetermined vertical interval and a predetermined horizontal interval. It is what.

According to a fifth technical means, in the fourth technical means, the plurality of auxiliary LEDs are arranged in a row in the horizontal direction at the horizontal interval, arranged in a row in the vertical direction at the vertical interval, and the horizontal direction. The auxiliary LED rows arranged in the vertical direction are separated from the outermost horizontal row of LEDs by a distance shorter than the vertical interval, and the auxiliary LED rows arranged in the vertical direction are shorter than the horizontal interval. Only apart from the outermost column of LEDs.

A sixth technical means is an image display device comprising the LED backlight device according to any one of the first to fifth technical means and a liquid crystal panel illuminated by the LED backlight device. .

  According to the present invention, it is possible to eliminate a lack of luminance at the outer peripheral portion of the screen while suppressing an increase in the number of installed LEDs and an excessive increase in power consumption without increasing the size and cost of the image display device to be mounted. Is possible.

  1A and 1B are diagrams for explaining a configuration example of a direct type LED backlight device according to the present invention. FIG. 1A is a cross-sectional view and FIG. 1B is a plan view. Moreover, FIG. 2 is a figure for demonstrating the example of arrangement | positioning of LED in the LED backlight apparatus of FIG. 1 and 2, 10 is an LED backlight device, 11 is a reflector, 12 is an LED, 13 is an auxiliary LED, 14 is a diffuser plate, 15 is another optical sheet, 16 is a housing of the LED backlight device, Reference numeral 17 denotes a liquid crystal panel.

  An LED backlight device 10 illustrated in FIG. 1 is a device that illuminates an object to be illuminated from the back by light emitted from an LED. FIG. 1 also shows a liquid crystal panel 17. The reflector 11 is preferably disposed on the bottom surface side of the housing 16 of the LED backlight device 10, and a plurality of LEDs 12 are disposed in a grid pattern on the top surface side.

  As a main feature of the present invention, auxiliary LEDs 13 for assisting the amount of light are arranged in a row on the outer peripheral portion of the plurality of LEDs 12. Therefore, the auxiliary LED 13 can be said to be the outermost peripheral LED. And these auxiliary | assistant LED13 shall be driven with the electric current lower than LED12. Thus, in the present invention, the auxiliary LED 13 is driven with a low current to assist the amount of light in the outer peripheral portion.

  Here, the light amount of the auxiliary LEDs 13 arranged in the outer periphery is made smaller than the light amount of the LEDs 12 arranged in a grid pattern on the inner side, but the light amount may be appropriately adjusted and determined according to the configuration of the actual image display device. For example, the auxiliary LED 13 may be supplied with a current that emits light at a light quantity ratio of about 1/4 to 1/2 of the LED 12.

Multiple LED12 are arranged on lattice points of a lattice with a predetermined lateral spacing X ₂ and a predetermined longitudinal spacing Y _2. Here it may be the same as the lateral spacing X ₂ and the longitudinal spacing Y _2. Even if the plurality of LEDs 12 are not arranged on such lattice points, the auxiliary LED 13 that is driven with a low driving current may be arranged on the outer peripheral portion thereof. For example, the LED 12 in the column and the row may be configured in a so-called staggered arrangement, and the auxiliary LEDs 13 may be arranged in a row on the outer peripheral portion thereof.

  The LED 12 and the auxiliary LED 13 may be provided on the substrate. For example, a plurality of units in which a plurality of LEDs 12 are arranged in an array on a substrate and auxiliary LEDs 13 are arranged on both ends of the LEDs are arranged in a plurality, and only the auxiliary LEDs 13 are arranged in an array on the substrate. The units can be arranged side by side at both ends.

  The reflection plate 11 may be arranged by opening a through hole and penetrating the individual LEDs 12 and the auxiliary LEDs 13 into the through hole. Further, a reflecting surface may be formed on the surface of the substrate on which the LED 12 and the auxiliary LED 13 are disposed by a technique such as printing, and the function of the reflecting plate 11 may be imparted to the LED substrate.

  In the present invention, the configuration and the number of the LEDs 12 and the auxiliary LEDs 13 are not basically limited at all, and a plurality of LEDs 12 are arranged on the back side of the liquid crystal panel 17, and the auxiliary LEDs 13 are arranged on the outer periphery of the LEDs 12. What is necessary is just to provide the structure by which. A preferable example of the auxiliary LED 13 will be described later. In addition, the LED backlight device according to the present embodiment may be an illumination method using the single-chip or multi-chip white LED as described above as the LED 12 and the auxiliary LED 13, and may be an RGB three-color LED. An illumination method in which LEDs are arranged may be used, and the LEDs to be used are not particularly limited. When three color LEDs are mounted, the LEDs 12 and the auxiliary LEDs 13 described in the present specification may be arranged so that the center of the positions of the three color LEDs comes to the center.

  Further, various electric circuit components (not shown) including an LED lighting circuit, a dimming control unit, an LED lighting circuit, and the like for controlling the lighting of the LED 12 and the auxiliary LED 13 are generally arranged on the back surface of the LED backlight device 10. However, the detailed positional relationship is not particularly limited.

  Light emitted from the LED 12 and the auxiliary LED 13 is diffused by the diffusion plate 14 and further receives a predetermined action by another optical sheet 15 to illuminate the liquid crystal panel 17 from the back side. As the other optical sheets 15, for example, an optical sheet such as a prism sheet is appropriately used. The liquid crystal panel 17 controls the orientation of the liquid crystal of each pixel according to the input video signal, and modulates the illumination light emitted from the LED 12 and the auxiliary LED 13. As a result, an image corresponding to the image signal is displayed on the liquid crystal panel 17.

As illustrated in FIG. 2, the plurality of auxiliary LEDs 13 are preferably arranged in a row in the horizontal direction at a horizontal interval X ₂ and arranged in a row in the vertical direction at a vertical interval Y ₂ . In particular, it is preferable that the auxiliary LEDs 13 have the same positional relationship as shown in FIG. Furthermore, the column of laterally disposed auxiliary LED13, the vertical direction by a distance _{Y 2} from a short distance _{Y 1} is separated from the LED12 of the outermost rows, rows of the vertically arranged auxiliary LED13 is transverse it is preferably arranged so that apart from the outermost columns of a short distance _{X 1} than the distance _{X 2} LED 12.

The arrangement interval (lateral interval X ₁ , vertical interval Y ₁ ) of the auxiliary LEDs ₁₃ from the outermost peripheral LED 12 may be appropriately adjusted and determined according to the configuration of the actual image display device. For example, the interval X arranged in a lattice pattern on the inside ₂ , about 1/2 of Y ₂ or the like may be employed. Further, the arrangement interval (lateral interval X ₀ , vertical interval Y ₀ ) from the inner side surface of the housing 16 of the auxiliary LED 13 may be appropriately adjusted and determined according to the configuration of the actual image display device, for example, the horizontal interval X ₁ , about the same as the longitudinal interval Y ₁ may be adopted. In the present invention, an auxiliary LED 13 for light amount correction (for auxiliary light source) is added between the inner side surface of the housing 16 and the LED 12, and the current value is optimized by increasing or decreasing a predetermined current in the auxiliary LED 13, It is only necessary to correct the decrease in the amount of light by causing the auxiliary LED 13 to emit light with that value.

  Further, the LED 12 emits light uniformly in all directions by arranging an optical lens on the LED chip, or the light amount is concentrated in the upward direction. On the other hand, it is preferable that the auxiliary LED 13 used in the present invention emits light with directivity in a plurality of directions so that the shortage of light in the outer peripheral portion can be well compensated even with a low driving current. That is, the auxiliary LED 13 in this embodiment has a shape in which the light dispersion direction can concentrate the light amount in a specific direction.

  For example, as illustrated in FIG. 2, the shape and the dispersion direction of the light emission may be different between the internal LED 12 and the surrounding auxiliary LED 13. In particular, in the example of FIG. 2, the LEDs 12 are circular, the auxiliary LEDs 13 are horizontally long (longitudinal vertically), and the dispersion direction of the light emission of the auxiliary LEDs 13 in the outer peripheral portion is, for example, horizontally along the periphery. Auxiliary LED 13 having a structure in the horizontal direction (vertical direction in the column) is used. Thus, by concentrating the dispersion direction of the light emission in the horizontal direction and the vertical direction, not in the entire circumferential direction, the light quantity in a specific direction can be concentrated and brightened even with a small driving current. Further, the amount of light can be arbitrarily adjusted by arbitrarily increasing / decreasing the LED current of the auxiliary LED 13.

  Thus, according to the present invention, it is possible to compensate for a decrease in the amount of light near the outermost periphery of a screen such as a liquid crystal screen by the arrangement of auxiliary LEDs with low power consumption, and to keep the entire screen at a uniform light amount. In the present invention, a decrease in luminance at the outer peripheral portion of the display device can be suppressed without using the diffuser plate 14 or in combination with the diffuser plate 14 as appropriate.

  FIG. 3 is a diagram for explaining another arrangement example of the LEDs in the LED backlight device of FIG. 1. In the arrangement example illustrated in FIG. 3, in the arrangement example of FIG. 2, the auxiliary LEDs 13 c are further provided at the four corners of the LED substrate to compensate for the light amounts at the four corners. Here, as the auxiliary LED 13c, for example, the same LED 12 may be used, and the auxiliary LED 13c may be driven at a lower current than the LED 12.

  FIG. 4 is a longitudinal sectional view showing a configuration example of an auxiliary LED applicable to the LED backlight device of the present invention, and FIG. 5 is a diagram for explaining the principle of an LED chip provided in the auxiliary LED of FIG. FIG. 6 and FIG. 6 are perspective views for explaining a configuration example of the LED chip of FIG. 4 to 6, 20 is an LED chip of the auxiliary LED 13, 21 is a P-type semiconductor, 21a is a P electrode (+), 22 is an N-type semiconductor, 22a is an N electrode (-), 23 is a light emission blocking portion, 30 Is an auxiliary LED, 31 is an LED chip substrate, 32 is a chip base, 33 is a phosphor, and 34 is a transparent resin.

  The auxiliary LED 13 described in FIGS. 1 to 3 may be configured by the auxiliary LED 30 illustrated in FIG. In the auxiliary LED 30, for example, the LED chip 20 is mounted on an LED chip substrate 31 such as a sapphire substrate, and the auxiliary LED 30 is mounted on a chip base 32 and is covered with a phosphor 33. It is covered with a transparent resin 34 such as resin or silicone. As illustrated in FIGS. 2 and 4, the auxiliary LED 30 preferably has an elongated cross-sectional shape.

  As shown in FIGS. 5 and 6, the LED chip 20 has a part of the joint portion between the P-type semiconductor 21 and the N-type semiconductor 22 (a central portion that leaves both ends) as compared with a normal LED chip. The light emission blocking portion 23 is formed of an insulator or a cavity, and emits light at at least both end portions (both side portions) sandwiching the light emission blocking portion 23. In the example of FIG. 6, as indicated by the P-type semiconductor and its emission blocking portion 23 in FIG. 6B and the N-type semiconductor and its emission blocking portion 23 in FIG. It has a U-shaped cross section with 22a near the center. With such a structure, an auxiliary LED having at least two directions can be formed. Even in this form, as described later in FIG. 7, the reflecting member may be disposed at a predetermined position of the transparent resin that becomes the outer frame of the LED.

  Here, in order to simplify the description, a homojunction double structure has been described. However, even in other structures, as the light emission blocking member 23, a part of the active layer in the double heterostructure or the quantum well structure. A part of the quantum well layer may be made of an insulator or the like so as to fulfill its function.

  The combination of the LED chip 20 and the phosphor 33 is such that white light is emitted when the light emitted from the LED chip 20 passes through the phosphor 33. For example, when the LED chip 20 is a blue LED chip, a yellow phosphor is used as the phosphor 33, and when the LED chip 20 is a purple LED chip, an RGB phosphor is used as the phosphor 33. Further, for example, when the LED chip 20 includes RGB LED chips of three colors or two color LED chips that are complementary colors, a transparent resin is used instead of the phosphor 33. The phosphor 33 may not be provided so as to cover the entire LED chip 20, and may be installed on the chip base 32 via a transparent resin or a space as a fluorescent plate.

  FIG. 7 is a longitudinal sectional view showing another configuration example of an auxiliary LED applicable to the LED backlight device of the present invention, in which 21 is a P-type semiconductor, 21a is a P electrode (+), and 22 is N Type semiconductor, 22a is an N electrode (-), 40 is an auxiliary LED, 41 is an LED chip substrate, 42 is a chip base, 43 is a phosphor, 44 is a transparent resin, 45 is a shielding member, 46 is a reflecting member at the top of the head, 47 is a reflecting member on the bottom surface.

  The auxiliary LED 13 described with reference to FIGS. 1 to 3 may be configured by the auxiliary LED 40 illustrated in FIG. The auxiliary LED 40 has an elongated cross-sectional shape, and a central portion in the longitudinal direction is shielded by a reflecting member (a reflecting plate or the like) that reflects emitted light to the inside.

  In the example of FIG. 7, the auxiliary LED 40 includes, for example, an LED chip composed of a P-type semiconductor 21 and an N-type semiconductor 22, their electrodes, and the like mounted on an LED chip substrate 41 such as a sapphire substrate. 42, and is covered with a fluorescent material 43, which is further covered with a transparent resin 44 such as an epoxy resin or silicone. The combination of the LED chip and the phosphor 43 is as described in FIG.

  In this example, a shielding member 45 (which may be a reflecting member) is provided at a location of the phosphor 43 located at the center of the LED chip, and light emission from the LED chip proceeds to both sides. . Further, a reflection member 46 is provided on the top of the transparent resin 44 so that the light does not pass from the top of the transparent resin 44, and the transparent resin is further transmitted so that the light reflected by the reflection member 46 efficiently travels on both sides. A reflection member 47 is also provided on the bottom surface of 44.

  FIG. 8 is a block diagram for explaining a configuration example of a liquid crystal display device including a backlight device applicable to the present invention. In this example, it is assumed that the LED backlight device as described above is applied for illumination of a liquid crystal panel (LCD) included in the liquid crystal display device.

  The video processing unit 51 processes a video signal input to the liquid crystal display device 50 or a video signal read from a recording medium of a recording / reproducing device built in the liquid crystal display device 50, and performs various image quality adjustment processes as necessary. To generate and output an image display signal such as RGB suitable for driving the liquid crystal panel 17.

  The LCD control unit 52 generates gradation data and a signal line control signal to be output to the source driver 53 in accordance with the RGB image display signal output from the video processing unit 51, and at the same time, the scanning line control signal to be output to the gate driver 54. And the image display control in the liquid crystal panel 17 is performed. Further, the LCD control unit 52 generates a backlight control signal to be output to the light source driving unit 55.

  The light source driving unit 55 sends a control signal to the horizontal driving circuit (X line driving circuit) 56 and the vertical driving circuit (Y line driving circuit) 57 based on the backlight control signal obtained from the LCD control unit 52. The horizontal drive circuit 56 and the vertical drive circuit 57 drive the LED backlight 58 and cause the LED and the auxiliary LED of the LED backlight 58 to emit light. Here, the horizontal drive circuit 56 includes data lines for connecting the LEDs for one row in the horizontal direction (X direction) and auxiliary LEDs in series for the number of rows of LEDs and auxiliary LEDs. Similarly, the vertical drive circuit 57 includes data lines for connecting the LEDs for one column in the vertical direction (Y direction) and auxiliary LEDs in series for the number of columns of LEDs and auxiliary LEDs.

  Then, the LED at the intersection of the data line to which the lighting control signal of the horizontal driving circuit 56 is applied and the data line to which the lighting control signal of the vertical driving circuit 57 is applied is lit by the control signal from the light source driving unit 55. Is done. For example, the LCD control unit 52 can generate XY address data for the LEDs to be turned on and the auxiliary LEDs, and the light source driving unit 55 can perform light emission control of the LEDs and the auxiliary LEDs according to the address data.

  Thus, in the present invention, an LED backlight system may be adopted in which LEDs and auxiliary LEDs are arranged in a matrix and each LED is individually lit and driven with an XY address. Note that the configuration for individually controlling the light emission of the plurality of LEDs and auxiliary LEDs arranged directly below is not limited to that described here, and may be a circuit that can individually control the light emission of the LEDs and auxiliary LEDs. It can be adopted as appropriate.

  Further, in addition to a configuration in which the plurality of LEDs and auxiliary LEDs are individually controlled to emit light, a plurality of adjacent LEDs and auxiliary LEDs may be unitized, and light emission control may be performed for each unitized LED and auxiliary LED. In this case, there is an advantage that the circuit configuration for controlling the light emission can be simplified.

  Such light emission control for each LED and auxiliary LED is performed when the light emission luminance of the LED turned off by the abnormality detection result is compensated for by the adjacent LED to control the light amount for illuminating the entire liquid crystal panel 17 to be constant. It is useful for such as. Here, for example, an abnormality detection unit that detects an abnormality in light emission due to breakage or disconnection may be provided for each LED and auxiliary LED.

  In addition, a luminance adjustment circuit for adjusting (dimming) the light emission luminance of each LED and auxiliary LED may be included in the light source drive unit 55, the horizontal drive circuit 56, or the vertical drive circuit 57. In this case, the backlight control signal output from the LCD control unit 52 includes a signal for instructing dimming control, and the luminance adjustment circuit emits the luminance of the LEDs and the auxiliary LEDs according to the control signal from the light source driving unit 55. Dimming.

  As the LED dimming control means in such a luminance adjustment circuit, a voltage (current) dimming method, a duty dimming method in which brightness is time-division, or the like can be applied. When the voltage (current) dimming method is applied, the input voltage or input current from a power supply circuit (not shown) is changed by a DC-DC converter or the like, and the LED or auxiliary LED is directly used according to the magnitude of the drive voltage (current). The light can be adjusted by changing the current. On the other hand, when the duty dimming method is applied, the luminance adjustment circuit generates a dimming pulse (PWM signal) for driving the LED and the auxiliary LED so that the duty ratio is in accordance with the PWM ratio setting data. By varying the pulse width, the brightness of the LED or auxiliary LED can be dimmed.

  In the present invention, as described with reference to FIGS. 1 to 7, the light emission is controlled so that the drive currents of the LED and the auxiliary LED are different at least at the time of full lighting. In order to make the drive currents different at least between the LED and the auxiliary LED, for example, the unitization as described above may be performed separately for the LED and the auxiliary LED. Moreover, you may adjust the brightness | luminance of LED and auxiliary | assistant LED of the outer peripheral part with the above-mentioned brightness | luminance adjustment circuit in view of the performance including the directivity of LED and auxiliary | assistant LED.

  FIG. 9 is a block diagram showing a configuration example of a liquid crystal television set configured as an image display device of the present invention. In the liquid crystal television device 70, the tuner 65 selects a channel from the television broadcast signal received by the antenna 64. The video input terminal 66 inputs a video signal from an AV device that is built in or externally connected to the liquid crystal television device 70. The switching unit 67 switches and outputs the television broadcast signal selected by the tuner 65 and the video signal input via the video input terminal 66.

  The video signal output from the switching unit 67 is processed by the video processing unit 51 and output to the LCD control unit 52. The video processing unit 51 performs a video signal generation process and various image quality adjustment processes from the input video signal. The video processing unit 51 performs composite signal YC separation processing, RGB signal decoding processing for generating RGB signals from YC signals, AD conversion processing, color space conversion processing, IP conversion processing, scaling processing, FRC processing, color correction processing, synchronization Video signal processing such as detection processing, γ correction processing, and OSD display processing is appropriately executed.

  The LCD control unit 52 generates gradation data and a signal line control signal to be output to the source driver of the liquid crystal panel (LCD) 17 according to the image display signal output from the video processing unit 51, and scan lines to be output to the gate driver. A control signal is generated and image display control in the liquid crystal panel 17 is performed. Further, the LCD control unit 52 generates a backlight control signal to be output to the light source driving unit 55 and performs light emission driving control of the LED backlight 58. The method described with reference to FIG. 8 can be applied to the drive control of the liquid crystal panel 17 and the light emission luminance control of the LED backlight 58.

  In the liquid crystal television device 70, the audio signal output from the switching unit 67 is processed by the audio processing unit 68 and output from the speaker 69. In addition, the remote control light receiving unit 61 receives a remote control operation signal by infrared rays transmitted from the remote control device 60 and sends it to the control unit 62. The control unit 62 detects and analyzes the remote control operation signal received by the remote control light receiving unit 61, and performs these operations on the tuner 65, the switching unit 67, the video processing unit 51, the LCD control unit 52, the audio processing unit 68, and the like. A control signal to be controlled is output. The control unit 62 uses programs and data stored in the memory 63. Further, the operation input by the user to the liquid crystal television device 70 can be executed using not only the remote control device 60 but also operation keys and switches provided in the main body operation unit of the liquid crystal television device 70.

  The image display device according to the present invention is not limited to the above-described liquid crystal television device, and various images having a configuration in which a display panel such as a liquid crystal panel is illuminated from the back to generate a display image. It can be applied to a display device.

It is a figure for demonstrating the structural example of the direct type | mold LED backlight apparatus which concerns on this invention. It is a figure for demonstrating the example of arrangement | positioning of LED in the LED backlight apparatus of FIG. It is a figure for demonstrating the other example of arrangement | positioning of LED in the LED backlight apparatus of FIG. It is longitudinal direction sectional drawing which shows one structural example of auxiliary LED applicable to the LED backlight apparatus of this invention. It is a figure for demonstrating the principle of the LED chip provided in auxiliary LED of FIG. It is a perspective view for demonstrating one structural example of the LED chip of FIG. It is longitudinal direction sectional drawing which shows the other structural example of auxiliary LED applicable to the LED backlight apparatus of this invention. It is a block diagram for demonstrating the structural example of the liquid crystal display device provided with the backlight apparatus applicable to this invention. It is a block diagram which shows the structural example of the liquid crystal television apparatus comprised as an image display apparatus of this invention. It is a schematic top view of the conventional LED backlight.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... LED backlight apparatus, 11 ... Reflection board, 12 ... LED, 13, 30, 40 ... Auxiliary LED, 13c ... Auxiliary LED of four corners, 14 ... Diffuser plate, 15 ... Optical sheet, 16 ... Housing | casing, 17 ... Liquid crystal panel (LCD), 20 ... LED chip, 21 ... P-type semiconductor, 21a ... P electrode (+), 22 ... N-type semiconductor, 22a ... N electrode (-), 23 ... Light emission blocking part, 31, 41 ... LED Chip substrate, 32, 42 ... Chip base, 33, 43 ... Phosphor, 34, 44 ... Transparent resin, 45 ... Shield member, 46 ... Reflective member on the top, 47 ... Reflective member on the bottom, 50 ... Liquid crystal display device, 51 ... Image processing unit 52 ... LCD control unit 53 ... Source driver 54 ... Gate driver 55 ... Light source driving unit 56 ... Horizontal driving circuit 57 ... Vertical driving circuit 58 ... LED backlight 60 ... Remote control device , 61 ... Remote control light receiving unit, 62 ... Control unit, 63 ... Memory, 64 ... Antenna, 65 ... Tuner, 66 ... Video input terminal, 67 ... Switching unit, 68 ... Audio processing unit, 69 ... Speaker, 70 ... Liquid crystal television apparatus.

Claims (6)

In an LED backlight device that illuminates an object to be illuminated from the back with light emitted from the LEDs, a plurality of LEDs are arranged, and a plurality of auxiliary LEDs for assisting the amount of light are arranged in a row on the outer peripheral portion thereof and, the auxiliary LED, the driven LED at lower current, LED backlight apparatus, characterized in that to emit light with a plurality directivity. 2. The LED backlight device according to claim 1 , wherein the auxiliary LED includes an LED chip, and the LED chip is a portion in which a part of a junction portion in the N-type semiconductor and the P-type semiconductor is an insulator or a cavity. An LED backlight device, wherein the LED backlight device is formed by being replaced, and emits light at at least both end portions sandwiching a portion made of the insulator or a cavity. 2. The LED backlight device according to claim 1 , wherein the auxiliary LED has an elongated cross-sectional shape, and a central portion in a longitudinal direction is shielded by a reflecting member that reflects emitted light inward. Backlight device. The LED backlight device according to any one of claims 1 to 3 , wherein the plurality of LEDs are arranged on lattice points of a lattice having a predetermined vertical interval and a predetermined horizontal interval. LED backlight device. 5. The LED backlight device according to claim 4 , wherein the plurality of auxiliary LEDs are arranged in a row in the horizontal direction at the horizontal interval, arranged in a row in the vertical direction at the vertical interval, and arranged in the horizontal direction. The auxiliary LED rows are spaced apart from the outermost row of LEDs by a distance shorter than the vertical spacing, and the auxiliary LED rows arranged in the vertical direction are shorter than the horizontal spacing by the distance. An LED backlight device characterized by being spaced apart from the outermost column of LEDs. And LED backlight device according to any one of claims 1 to 5, the image display apparatus characterized by comprising a liquid crystal panel illuminated by the LED backlight device.

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