JP2013157083A - Backlight device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin backlight device, and a display device.SOLUTION: A display device includes one or a plurality of light sources, a display panel, a first optical element, and a second optical element. The display panel is arranged in opposition to the light source(s). The first optical element is arranged between the light source and the display panel, and diffuses and transmits part of light irradiated from the light source to the display panel, and reflects part of the light. The second optical element is arranged between the light source and the first optical element, and transmits the light irradiated from the light source, and reflects the light reflected from the first optical element.

Description

  Embodiments described herein relate generally to a backlight device and a display device.

  In recent years, a liquid crystal display (LCD) has been widely used. The LCD includes a liquid crystal panel configured by disposing a liquid crystal material between a pair of glass substrates, and a backlight device that irradiates the liquid crystal panel with light from the back surface of the liquid crystal panel.

  As a light source of the backlight device, for example, an organic EL (Electro-Luminescence) light source can be considered. However, it is difficult to manufacture a large organic EL light source, and a plurality of small organic EL light sources are arranged and used. However, the liquid crystal panel above the gap between the organic EL light sources becomes dark.

  Therefore, at present, backlight devices using LEDs (Light Emitting Diodes) have become mainstream. Backlight devices using LEDs are roughly classified into two types, an edge type and a direct type.

  An edge-type backlight device irradiates light from a light source such as an LED toward a side surface of a light guide plate disposed on the back side of the liquid crystal panel, and widely diffuses the light facing the liquid crystal panel of the light guide plate It is taken out from. According to this method, the backlight device can be made thin, but on the other hand, if the size is increased, the center of the liquid crystal panel cannot be illuminated brightly, so that uneven brightness is likely to occur, or the bezel width needs to be widened in order to arrange the light source. There is a problem. If the bezel width is wide, the display area may appear small.

  On the other hand, a direct-type backlight device has light sources arranged in an array just below a liquid crystal panel, and irradiates the liquid crystal panel with light through a diffusion plate or the like. According to this method, in contrast to the edge type, since the center of the liquid crystal panel can be illuminated brightly, luminance unevenness is difficult to occur and the bezel width can be reduced, but there is a problem that the backlight device becomes thick. .

JP 2007-25187 A

  A thin backlight device and a display device are provided.

  According to the embodiment, a display device including one or more light sources, a display panel, a first optical member, and a second optical member is provided. The display panel is provided to face the light source. The first optical member is provided between the light source and the display panel, and diffuses and transmits part of the light emitted from the light source to the display panel and reflects a part thereof. The second optical member is provided between the light source and the first optical member, transmits light emitted from the light source, and reflects light reflected from the first optical member.

1 is a schematic block diagram of an image display system including a display device 110 according to an embodiment. 1 is a schematic block diagram of a display module 200. FIG. 1 is a schematic configuration diagram of a liquid crystal panel 1 and a backlight device 6. FIG. FIG. 3 is a cross-sectional view of the liquid crystal panel 1 and the backlight device 6. 1 is a schematic cross-sectional view of an organic EL light source 12. Sectional drawing which shows the organic light emitting layer 23 in detail. The figure which shows the ray path of the light irradiated from the organic EL light source 12. FIG. The figure which shows the ray path of the light irradiated from the organic EL light source 12. FIG. The figure which shows the ray path of the light irradiated from the organic EL light source 12. FIG.

  Hereinafter, embodiments will be specifically described with reference to the drawings.

  FIG. 1 is a schematic block diagram of an image display system including a display device 110 according to an embodiment.

  The image display device 110 includes a control unit 156 that controls the operation of each unit, an operation unit 116, and a light receiving unit 118. The control unit 156 includes a ROM (Read Only Memory) 157, a RAM (Random Access Memory) 158, a CPU (Central Processing Unit) 159, and a flash memory 160.

  The control unit 156 is a system control program and various processing programs stored in advance in the ROM 157 according to an operation signal input from the operation unit 116 or an operation signal transmitted from the remote controller 117 and input via the light receiving unit 118. Start up. The control unit 156 uses the RAM 158 as a work memory of the CPU 159, and controls the operation of each unit according to the activated program. The control unit 156 stores and uses information necessary for various settings in a flash memory 160 that is a nonvolatile memory such as a NAND flash memory.

  The image display apparatus 110 includes an input terminal 144, a tuner 145, a PSK (Phase Shift Keying) demodulator 146, a TS (Transport Stream) decoder 147a, and a signal processing unit 120.

  The input terminal 144 transmits the satellite digital television broadcast signal received by the BS / CS digital broadcast reception antenna 143 to the satellite digital broadcast tuner 145. The tuner 145 tunes the received digital broadcast signal and transmits the tuned digital broadcast signal to the PSK demodulator 146. The PSK demodulator 146 demodulates the TS from the digital broadcast signal and transmits the demodulated TS to the TS decoder 147a. The TS decoder 147a decodes the TS into a digital signal including a digital video signal, a digital audio signal, and a data signal, and transmits these to the signal processing unit 120.

  Here, the digital video signal is a digital signal related to video that can be output by the image display device 110, and the digital audio signal is a digital signal related to audio that can be output from the image display device 110. The data signal is a digital signal indicating various information about the demodulated service.

  In addition, the image display device 110 includes an input terminal 149, a tuner unit 150 having two tuners 150a and 150b, two OFDM (Orthogonal Frequency Division Multiplexing) demodulators 151, two TS decoders 147b, and an analog tuner. 168 and an analog demodulator 169.

  The input terminal 149 transmits the terrestrial digital television broadcast signal received by the terrestrial digital broadcast receiving antenna 148 to the terrestrial digital broadcast tuner unit 150. The tuners 150a and 150b of the tuner unit 150 each tune the received digital broadcast signal, and transmit the tuned digital broadcast signal to two OFDM demodulators 151. The OFDM demodulator 151 demodulates the TS from the digital broadcast and transmits the demodulated TS to the corresponding TS decoder 147b. The TS decoder 147b decodes the TS into a digital video signal, an audio signal, etc., and transmits these to the signal processing unit 120. The terrestrial digital television broadcast acquired by each of the tuners 150a and 150b of the tuner unit 150 includes a digital video signal, a digital audio signal, and a data signal by the OFDM demodulator 151 and the TS decoder 147b, respectively. After being decoded as a digital signal, it can be transmitted to the signal processing unit 120.

  The antenna 148 can also receive a terrestrial analog television broadcast signal. The received terrestrial analog television broadcast signal is distributed by a distributor (not shown) and transmitted to the analog tuner 168. The analog tuner 168 tunes the received analog broadcast signal and transmits the tuned analog broadcast signal to the analog demodulator 169. The analog demodulator 169 demodulates the analog broadcast signal and transmits the demodulated analog broadcast signal to the signal processing unit 120. Further, as an example, the image display apparatus 110 can also watch CATV by connecting a CATV (Common Antenna Television) tuner to an input terminal 149 to which an antenna 148 is connected.

  In addition, the image display device 110 includes a line input terminal 137, an audio processing unit 153, a speaker 115, a graphic processing unit 152, an OSD (On Screen Display) signal generation unit 154, a video processing unit 155, A display module 200.

  The signal processing unit 120 performs appropriate signal processing on the digital signal transmitted from the TS decoders 147a and 147b or the control unit 156. More specifically, the signal processing unit 120 separates the digital signal into a digital video signal, a digital audio signal, and a data signal. The separated digital video signal is transmitted to the graphic processing unit 152, and the audio signal is transmitted to the audio processing unit 153. The signal processing unit 120 converts the broadcast signal transmitted from the analog demodulator 169 into a video signal and an audio signal in a predetermined digital format. The video signal converted to digital is transmitted to the graphic processing unit 152, and the audio signal is transmitted to the audio processing unit 153. The signal processing unit 120 also performs predetermined digital signal processing on the input signal from the line input terminal 137.

  The audio processing unit 153 converts the input audio signal into an analog audio signal in a format that can be reproduced by the speaker 115. The analog audio signal is transmitted to the speaker 115 and reproduced.

  The OSD signal generation unit 154 generates an OSD signal for displaying a UI (user interface) screen or the like under the control of the control unit 156. The data signal separated from the digital broadcast signal in the signal processing unit 120 is converted into an OSD signal of an appropriate format by the OSD signal generation unit 154 and transmitted to the graphic processing unit 152.

  The graphic processing unit 152 performs a decoding process on the digital video signal transmitted from the signal processing unit 120. The decoded video signal is combined with the OSD signal transmitted from the OSD signal generation unit 154 to be combined and transmitted to the video processing unit 155. The graphic processing unit 152 can also selectively transmit the decoded video signal or OSD signal to the video processing unit 155.

  The video processing unit 155 converts the signal transmitted from the graphic processing unit 152 into an analog video signal in a format that can be displayed on the display module 200. The analog video signal is transmitted to the display module 200 and displayed. Details of the display module 200 will be described later with reference to FIG.

  Further, the image display device 110 includes a LAN (Local Area Network) terminal 131, a LAN I / F (Interface) 164, a USB (Universal Serial Bus) terminal 133, a USB I / F 165, and an HDD (Hard Disk Drive). 170.

  The LAN terminal 131 is connected to the control unit 156 via the LAN I / F 164. The LAN terminal 131 is used as a general LAN-compatible port using Ethernet (registered trademark). In the present embodiment, a LAN cable is connected to the LAN terminal 131 and can communicate with the Internet 130.

  The USB terminal 133 is connected to the control unit 156 via the USB I / F 165. The USB terminal 133 is used as a general USB compatible port. For example, a mobile phone, a digital camera, a card reader / writer for various memory cards, an HDD, a keyboard, and the like are connected to the USB terminal 133 via a hub. The control unit 156 can perform communication (transmission / reception) of information with a device connected via the USB terminal 133.

  The HDD 170 is a magnetic storage medium built in the image display device 110 and has a function of storing various types of information that the image display device 110 has.

  FIG. 2 is a schematic block diagram of the display module 200. The display module 200 includes a liquid crystal panel (display panel) 1, a timing controller 2, a gate driver 3, a source driver 4, a backlight controller 5, and a backlight device 6.

  The liquid crystal panel 1 has a structure in which a pair of glass substrates are disposed to face each other and a liquid crystal material is disposed between the glass substrates. The liquid crystal panel 1 includes a plurality of (for example, 1080) scanning lines, a plurality of (for example, 1920 * 3) signal lines, and liquid crystal pixels formed at each intersection of the scanning lines and the signal lines.

  The timing controller 2 supplies an input video signal input from the video processing unit in FIG. 1 to the source driver 4 and controls operation timings of the gate driver 3, the source driver 4, and the backlight controller 5.

  The gate driver 3 sequentially selects one of the scanning lines. The source driver 4 supplies the input video signal to the signal line of the liquid crystal panel 1. This input video signal is supplied to the liquid crystal pixel connected to the scanning line selected by the gate driver 3, and the orientation of the liquid crystal material in the liquid crystal pixel changes according to the voltage of the input video signal. The gate driver 3 and the source driver 4 constitute a panel controller.

  On the other hand, the backlight device 6 is provided on the back surface of the liquid crystal panel 1 and irradiates the liquid crystal panel 1 with light. Of the irradiated light, light having an intensity corresponding to the orientation of the liquid crystal material is transmitted through the liquid crystal material and displayed on the liquid crystal panel 1.

  FIG. 3 is a schematic configuration diagram of the liquid crystal panel 1 and the backlight device 6. FIG. 4 is a cross-sectional view of the liquid crystal panel 1 and the backlight device 6. The backlight device 6 includes a substrate 11 such as aluminum, an organic EL light source 12 disposed on the substrate 11, a diffusion plate 13 disposed between the organic EL light source 12 and the liquid crystal panel 1, and the organic EL light source 12. And a translucent reflection sheet 14 disposed between the diffusion plate 13 and the diffusion plate 13. In addition to these, an optical sheet may be provided in the backlight device 6 as appropriate.

  The organic EL light source 12 emits light toward the liquid crystal panel 1. The diffusion plate 13 diffuses and transmits a part of the light emitted from the organic EL light source 12 to the liquid crystal panel 1 and reflects a part to the translucent reflection sheet 14 so that the luminance of the liquid crystal panel 1 becomes uniform. . The translucent reflection sheet 14 transmits the light emitted from the organic EL light source 12 to the diffusion plate 13 and reflects the light reflected from the diffusion plate 13 to the diffusion plate 13.

  By providing the diffusing plate 13, the backlight device 6 can be thinned and luminance unevenness of the liquid crystal panel 1 can be suppressed. Moreover, the light irradiated from the organic EL light source 12 can be used efficiently by providing the translucent reflective sheet 14. Further, by using a surface light source such as the organic EL light source 12, the backlight device 6 can be particularly thinned. Hereinafter, each member will be described in more detail.

  The organic EL light source 12 is a substantially square having sides of about 20 cm. As shown in FIG. 3, the organic EL light sources 12 are arranged in an array on the substrate 11 so as to be spaced apart from each other, with a gap between them. In this gap, wiring (not shown) for driving and controlling the organic EL light source 12 is provided. In addition, a reflective film (not shown) may be formed in the gap in order to increase the extraction efficiency of light emitted from the organic EL light source 12.

  In the figure, an example in which eight organic EL light sources 12 are arranged is shown. For example, one organic EL light source 12 may be used.

  FIG. 5 is a schematic cross-sectional view of the organic EL light source 12. The organic EL light source 12 includes a substrate 21 such as glass, a cathode 22 such as aluminum, an organic light emitting layer 23 that emits light, a light-transmitting anode 24 made of ITO (Indium Tin Oxide), and a resin or the like. And a stopper 25. In order to prevent the organic light emitting layer 23 from being deteriorated by contact with moisture or air, the organic light emitting layer 23 is enclosed and sealed with a sealing material 25.

  FIG. 6 is a cross-sectional view showing the organic light emitting layer 23 in more detail. The organic light emitting layer 23 includes an electron injection layer EIL, an electron transport layer ETL, a light emission layer EML, a hole transport layer HTL, and a hole injection layer HIL. Note that in order to emit white light, the light emitting layer EML is a stacked or mixed layer of organic materials that emit red, green, and blue colors. In FIG.

  Holes injected from the anode 24 of FIG. 5 into the light emitting layer EML via the hole injection layer HIL and hole transport layer HTL of FIG. 6, and the electron injection layer EIL and electron transport of FIG. Electrons injected into the light emitting layer EML through the layer ETL are recombined to emit light with a color corresponding to the impurities contained in the light emitting layer EML.

  As shown in FIG. 5, the sealing material 25 does not emit light. Moreover, as shown in FIG. 4, there is a gap between the organic EL light sources 12. Further, the organic EL light source 12 is not disposed near the outer periphery of the substrate 11. Therefore, in the present embodiment, the liquid crystal panel 1 above the sealing material 25, above the gap, and above the outer periphery of the substrate 11 (hereinafter collectively referred to as a non-light emitting region) becomes dark and luminance unevenness occurs. It is intended to suppress the occurrence.

  In the present embodiment, an example in which the organic EL light source 12 is used to make the backlight device 6 particularly thin and operate with low power consumption is shown, but other surface light sources that emit light to some extent may be used. . For example, the surface light source may be configured by a module or the like that includes a point light source such as an LED and emits light as a surface light source.

  Next, the diffusion plate 13 shown in FIGS. 3 and 4 will be described. On one surface or both surfaces of the diffusing plate 13, a reflective coating having an opening pattern formed of a plurality of minute holes (microholes) that transmits light is applied. Therefore, in the light irradiated to the diffuser plate 13, the light hitting the portion where the reflective coating is applied reflects to the organic EL light source 12 side, while hitting the portion where the reflective coating is not applied (that is, a hole). The light is also diffused above the non-light emitting area and is transmitted to the liquid crystal panel 1.

  In consideration of the arrangement and orientation distribution of the organic EL light source 12, at least one of the shape, size, density, etc. of the opening pattern is adjusted so that the luminance of the liquid crystal panel 1 becomes uniform when the organic EL light source 12 is fully lit. To do. For example, the hole formed in the portion facing the organic light emitting layer 23 of the organic EL light source 12 is made smaller than the hole formed in the portion facing the non-light emitting region.

  By disposing such a diffuser plate 13, the backlight device 6 can be thinned and luminance unevenness of the liquid crystal panel 1 can be suppressed. A diffusion sheet may be used in place of the diffusion plate 13.

  Next, the translucent reflective sheet 14 shown in FIGS. 3 and 4 will be described. The translucent reflective sheet 14 is a sheet in which a hologram is formed on one side of a transparent polymer film, for example, and is a relatively inexpensive member. And it shows a high transmittance for the light emitted from the organic EL light source 12. Ideally, the transmittance is desirably 100%, but the transmittance may be high to some extent, and some light may be absorbed or reflected. On the other hand, the light reflected from the reflective coating of the diffusion plate 13 and reaching the translucent reflective sheet 14 exhibits a high reflectance. Similarly, it is desirable that the reflectance is ideally 100%, but the reflectance may be high to some extent, and some light may be absorbed or transmitted.

  If the translucent reflection sheet 14 is not provided, the light reflected by the diffusion plate 13 reaches the organic EL light source 12. Since the organic EL light source 12 does not reflect much light, it cannot be extracted from the liquid crystal panel 1 side. As a result, the light utilization efficiency decreases. On the other hand, in this embodiment, since the translucent reflection sheet 14 is provided and the light reflected by the diffusion plate 13 is further reflected to the diffusion plate 13, the light can be used efficiently and the liquid crystal panel 1 can be irradiated sufficiently brightly. .

  Next, the behavior (ray path) of light emitted from the organic EL light source 12 will be described.

  7 to 9 are diagrams showing a ray path of light emitted from the organic EL light source 12. First, as shown in FIG. 7, most of the light emitted from the organic EL light source 12 passes through the translucent reflective sheet 14 and reaches the diffusion plate 13. Next, as shown in FIG. 8, among the light reaching the diffusion plate 13, the light hitting the hole where the reflective coating is not formed is diffused inside the diffusion plate 13 and transmitted therethrough. 1 is irradiated. On the other hand, the light hitting the place where the reflective coating is formed is reflected to the translucent reflective sheet 14 side. Furthermore, as shown in FIG. 9, most of the light reflected by the translucent reflection sheet 14 is reflected by the translucent reflection sheet 14 to the diffusion plate 13.

  In this way, the light emitted from the organic EL light source 12 is diffused while being repeatedly reflected between the diffuser plate 13 and the translucent reflective sheet 14, and in the process, a part of the light is applied to the reflective film of the diffuser plate 13. The liquid crystal panel 1 is transmitted through the formed hole.

  As described above, in the present embodiment, the diffusion plate 13 that transmits part of light and reflects part of light is provided between the organic EL light source 12 and the liquid crystal panel 1. Therefore, the backlight device 6 can be thinned and the liquid crystal panel 1 can be uniformly irradiated. Further, a translucent reflection sheet 14 is provided between the organic EL light source 12 and the diffusion plate 13. Therefore, the light irradiated from the organic EL light source 12 can be used efficiently.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 6 Backlight apparatus 11 Board | substrate 12 Organic EL light source 13 Diffusing plate 14 Translucent reflective sheet

Claims (19)

One or more light sources;
A display panel provided facing the light source;
A first optical member that is provided between the light source and the display panel, diffuses a part of the light emitted from the light source, transmits the light to the display panel, and reflects a part thereof;
A second optical member provided between the light source and the first optical member, which transmits light emitted from the light source and reflects light reflected from the first optical member. Display device.   The first optical member diffuses and transmits part of the light emitted from the light source to the display panel and reflects part of the light so that the brightness of the display panel is uniform. Display device. The first optical member includes:
A diffusion plate or diffusion sheet;
The display device according to claim 1, further comprising: a reflection member provided in the diffusion plate or the diffusion sheet and having a plurality of holes formed therein.   The display device according to claim 3, wherein at least one of a size, a shape, and a density of the plurality of holes is adjusted so that luminance of the display panel is uniform. The plurality of light sources are arranged with a gap between each other,
The display device according to claim 3, wherein the hole formed in a portion facing the light source is smaller than a hole formed in a portion facing the gap. Equipped with a substrate,
The light source is provided on a part of the substrate;
The display device according to claim 1, wherein a reflective material is formed on a portion of the substrate where the light source is not provided. The second optical member is
For light emitted from the light source, the transmittance is a first predetermined value or more,
The display device according to claim 1, wherein the reflectance of the light reflected from the first optical member has a reflectance equal to or higher than a second predetermined value.   The display device according to claim 1, wherein the light source is a surface light source.   The display device according to claim 1, wherein the light source is an organic EL light source. It has a tuner that receives and tunes broadcast waves,
The display device according to claim 1, wherein the display panel displays an image corresponding to the tuned broadcast wave. A backlight device for a display device having a display panel,
One or more light sources provided to face the display panel;
A first optical member that is provided between the light source and the display panel, diffuses a part of the light emitted from the light source, transmits the light to the display panel, and reflects a part thereof;
A second optical member provided between the light source and the first optical member, which transmits light emitted from the light source and reflects light reflected from the first optical member. Backlight device.   The first optical member diffuses and transmits part of the light emitted from the light source to the display panel and reflects part of the light so that the brightness of the display panel is uniform. Backlight device. The first optical member includes:
A diffusion plate or diffusion sheet;
The backlight device according to claim 11, further comprising: a reflection member provided in the diffusion plate or the diffusion sheet and formed with a plurality of holes.   The backlight device according to claim 13, wherein at least one of a size, a shape, and a density of the plurality of holes is adjusted so that luminance of the display panel is uniform. The plurality of light sources are arranged with a gap between each other,
The backlight device according to claim 13 or 14, wherein the hole formed in a portion facing the light source is smaller than a hole formed in a portion facing the gap. Equipped with a substrate,
The light source is provided on a part of the substrate;
The backlight device according to claim 11, wherein a reflective material is formed on a portion of the substrate where the light source is not provided. The second optical member is
For light emitted from the light source, the transmittance is a first predetermined value or more,
The backlight device according to any one of claims 11 to 16, wherein the light reflected from the first optical member has a reflectance equal to or higher than a second predetermined value.   The backlight device according to claim 11, wherein the light source is a surface light source.   The backlight device according to claim 11, wherein the light source is an organic EL light source.

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