JP2009076349A - Illumination device, electro-optical device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device capable of utilizing efficiently light from a light source, and to provide an electro-optical device and electronic equipment. <P>SOLUTION: The illumination device is provided with a light source 12 and a light guide plate 210 which makes light from the light source 12 enter from light incident end faces 212a, 212b and emits from a light outgoing face. A recess 210a of which inner faces are incident end faces 212a, 212b is formed in the light guide plate 210 and the light source 12 is arranged in the recess 210a, and a total reflection face 213 which totally reflects the light in the light guide plate 210 entered from the light incident end faces 212a, 212b inside the light guide plate 210, and takes into inside is installed at the side part of the light-emitting face 12a of the light source 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an illumination device, an electro-optical device, and an electronic apparatus.

Currently, in various electronic devices such as mobile phones and portable information terminals, liquid crystal devices are used as display units for visually displaying various types of information.
As such a liquid crystal device, a device including a liquid crystal panel which is an example of a display panel, a backlight (illumination device), and a frame for housing the liquid crystal panel and the backlight is known (for example, Patent Documents). 1).

The liquid crystal panel includes a pair of substrates, a sealing material formed between the pair of substrates along the outer periphery of the substrate, and a liquid crystal disposed in a region surrounded by the pair of substrates and the sealing material. It is what is done. The backlight generally includes a light guide plate made of a light-transmitting resin and a light source that generates light. As such a light source, an LED (Light Emitting Diode) is used, and light emitted from the light source is introduced into the light guide plate, travels through the light guide plate, and then from the light exit surface of the light guide plate. Display is performed by being emitted into the liquid crystal layer of the liquid crystal device as planar light.
JP 2005-347014 A

  However, among the light emitted from the LEDs constituting the light source, for example, light having an angle substantially parallel to the light emitting surface is difficult to efficiently guide into the light guide plate, and the light from the light source can be used more efficiently. The provision of technology is desired.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an illumination device, an electro-optical device, and an electronic apparatus that can efficiently use light from a light source.

  In order to solve the above-described problems, an illumination device according to the present invention includes a light source and a light guide plate that emits light from the light source through a light exit surface while allowing light from the light incident end surface to enter the light guide plate. The inner surface is formed with a concave portion that forms the light incident end surface, and the light source is disposed in the concave portion, and the light in the light guide plate incident from the light incident end surface is totally reflected in the light guide plate. The total reflection surface taken in is provided on the side of the light emitting surface of the light source.

  According to the illumination device of the present invention, light on the light emitting surface of the light source provided in the recess is taken into the light guide plate by the total reflection surface. In addition, since the inner surface of the concave portion in which the light source is disposed is a light incident end surface, the light on the light emitting surface can be transmitted by the total reflection surface without strictly adjusting the position of the light source to be disposed by arranging the light source in the concave portion. It can be taken into the light guide plate. Therefore, the light from the light source can be used efficiently, and high light utilization efficiency can be obtained.

Moreover, in the said illuminating device, it is preferable to provide the said some light source, and to provide the said total reflection surface corresponding to each said light source, respectively.
According to this configuration, it is possible to satisfactorily take light from the light emitting surface into the light guide plate in a plurality of light sources, and a larger amount of light can be obtained.

Moreover, in the said illuminating device, it is preferable that the said light source is arrange | positioned at the corner | angular part of the said light-guide plate.
According to this configuration, for example, the present invention can be applied by using the end surface of the light guide plate constituting the corner portion as the total reflection surface without using the existing light guide plate.

Moreover, in the said illuminating device, it is preferable that the said total reflection surface is provided over the perimeter of the said light emission surface of the said light source.
According to this structure, the light of all the directions radiate | emitted radially from the light emission surface of a light source can be taken in in a light-guide plate by a total reflection surface, and the light utilization efficiency in a light source can be improved more.

Moreover, in the said illuminating device, the said light emission surface side of the said light source is joined to the said light-guide plate via transparent resin, and the said transparent resin is comprised from the material which has a refractive index substantially equivalent to the said light-guide plate. Is preferred.
According to this configuration, the light transmitted through the transparent resin can eliminate the loss due to refraction at the interface with the light guide plate, and the light utilization efficiency can be further improved.

  An electro-optical device of the present invention includes the above-described illumination device and a light modulation device that modulates light from the illumination device.

  According to the electro-optical device of the present invention, since the illumination device includes the light source having high light utilization efficiency as described above, the electro-optical device itself has high display quality and high reliability. Become.

  An electronic apparatus according to the present invention includes the above-described electro-optical device.

  According to the electronic apparatus of the present invention, since the electronic apparatus includes the high-reliability electro-optical device having a good display quality as described above as a display unit, the electronic apparatus itself also has high display performance. High reliability provided.

Hereinafter, the present invention will be described with reference to some embodiments.
Of course, the present invention is not limited to the embodiment. In the following description, various structures will be exemplified using drawings, but the structures shown in these drawings may be shown with different dimensions from the actual structures in order to show the characteristic parts in an easy-to-understand manner. There is.

(Liquid crystal device)
Hereinafter, a liquid crystal device will be described as an example of an electro-optical device according to the invention. The liquid crystal device includes the lighting device of the present invention. FIG. 1 is an exploded perspective view of the liquid crystal device according to the present embodiment. 2 is a plan view showing a main part of the lighting device, FIG. 3 is a view for explaining the main part of the light guide plate, and FIG. 4 is a diagram schematically showing a bonding structure of the lighting device.

  As shown in FIG. 1, the liquid crystal device 1 includes a liquid crystal panel (light modulation device) 100, a driving FPC (Flexible Printed Circuit) substrate 10 connected to the liquid crystal panel 100, and a back bonded to the liquid crystal panel 100. It includes a light (illuminating device) 200 and a frame 300 that houses the liquid crystal panel 100 and the backlight 200. Furthermore, the liquid crystal device 1 of the present embodiment includes a light source FPC board 18 including LEDs 12 that serve as the light source of the backlight 200 in addition to the driving FPC board 10 that drives the liquid crystal panel 100.

Next, a schematic configuration of the liquid crystal device 1 will be described focusing on the frame 300.
The light guide plate 210 is fitted into the frame 300 from the back side. On the back side of the frame 300, a reflection plate 223 is disposed so as to cover the back side of the light guide plate 210.
On the other hand, the light source FPC board 18 provided with the LEDs 12 is arranged on the surface side of the frame 300 via an adhesive sheet (not shown). Further, a plurality of optical sheets (diffusion plate 222, prism sheets 221, 220), adhesive sheet 20 (display panel side adhesive), and liquid crystal panel 100 are laminated on the light emitting surface 211a of the light guide plate 210 in this order.

  The liquid crystal panel 100 includes a first substrate 3 and a second substrate 2 and is bonded to each other with a square or rectangular shape and an annular sealing material. A gap, a so-called cell gap, is formed between the substrates 2 and 3, and a liquid crystal (electro-optic material), for example, TN (Twisted Nematic) liquid crystal is sealed in the cell gap to form a liquid crystal layer (not shown). is doing.

  As shown in FIG. 1, the frame 300 has a substantially frame shape, specifically, a frame shape in which a rectangular central portion is hollowed in the present embodiment. The frame 300 is provided with recesses 300 a corresponding to the plurality of protrusions 210 e of the light guide plate 210. The light guide plate 210 is fixed to the frame 300 by fitting the protrusion 210e into the recess 300a. The light guide plate 210 is fitted from the back side of the frame 300.

  Further, the frame 300 is provided with LED notches 310b formed corresponding to the LEDs 12. By fitting the LED 12 into the LED cutout portion 310b, the light guide plate 210 and the LED 12 are disposed adjacent to each other in the frame 300, and the LED 12 is disposed opposite to one end surface of the light guide plate 210.

  The light guide plate 210 can uniformly irradiate the liquid crystal panel 100 with the light emitted from the LEDs 12 to the liquid crystal panel 100 disposed corresponding to the light guide plate 210.

  The light source FPC board 18 is disposed on the light guide plate 210 in a state in which a part of the LED 12 is fitted into the LED notch 310 b of the frame 300. Thereby, the position of the light emitting surface 12a of the LED 12 with respect to the light incident end surface 212 of the light guide plate 210 is established, and the light of the LED 12 can enter the light guide plate 210.

  Further, the light source FPC board 18 has a connection end 18d drawn to the outside of the frame 300, and each LED 12 is driven by supplying a control signal or the like from the outside by an external device connected to a part thereof. It has become so. The connection end 18d is held in the recess 330 of the frame 300 shown in FIG.

  Further, a diffusion plate 222, two prism sheets 221 and 220, and a frame-shaped adhesive sheet 20 are disposed on the light guide plate 210, and the diffusion plate 222 and the two prism sheets 221 and 220 are formed by the adhesive sheet 20. The light source plate 210 including the light source FPC board 18 is fixedly disposed.

  As shown in FIGS. 1 and 2, the adhesive sheet 20 is a sheet that can be bonded on both sides, has a frame shape along the upper surface 301 of the frame 300, and is connected to the light guide plate 210 as described above. An overhang portion 20 a that can cover the FPC board 18 is provided. The projecting portion 20 a is attached to the upper surface 301 of the frame 300 so as to cover the light source FPC board 18. Further, the adhesive sheet 20 has a light shielding property and prevents light leakage from the backlight 200.

  The liquid crystal panel 100 is bonded to the upper surface 301 of the frame 300 and the surface 18 a (that is, the backlight 200) of the light source FPC board 18 via the adhesive sheet 20 and is accommodated in the frame 300. At this time, the driving FPC board 10 is held in the recess 320 of the frame 300.

  A reflective plate 223 is attached to the back side of the frame 300 so as to cover the light guide plate 210 and the frame 300. The reflection plate 223 is for reflecting the light emitted from the light guide plate 210 toward the liquid crystal panel 100. The diffusion plate 222 is for making the luminance of the light in the display region V more uniform. The two prism sheets 220 and 221 are for adjusting the orientation angle of the emitted light and improving the front luminance.

  That is, the backlight 200 is accommodated in the substantially rectangular light guide plate 210 having the light emitting surface 211a facing the second substrate 2 side of the liquid crystal panel 100 and the LED notch 310b of the frame 300 when the liquid crystal device 1 is assembled. Diffusion as a rectangular sheet-like optical component arranged in order from the light guide plate 210 toward the liquid crystal panel 100 between the liquid crystal panel 100 and the light guide plate 210, and the light source FPC board 18 having the LED 12 as the light source. A plate 222, two prism sheets 220 and 221, and a reflector 223 as a rectangular sheet-like optical component that is stacked on the back surface 211 b of the light guide plate 210 opposite to the light exit surface 211 a. It is configured.

  The liquid crystal device according to this embodiment is characterized by the backlight 200. Hereinafter, the light guide plate 210 that is a component of the backlight 200 will be described in detail.

(Light guide plate)
The light guide plate 210 is formed from acrylic resin, polycarbonate, or the like, and acrylic resin is used in this embodiment.
In this embodiment, as shown in FIG. 2, a notch (recess) 210a is formed on one end of the light guide plate 210, and the inner surface of the notch 210a forms a light incident end surface 212 of the light guide plate. Yes. That is, the light incident end surface 212 of the light guide plate 210 in the present embodiment includes a light incident end surface 212b facing the surface along the short side direction of the LED 12 in addition to the light incident end surface 212a facing the light emitting surface 12a of the LED 12. .

  Light emitted from the light emitting surface 12a of the LED 12 is well taken into the light incident end surface 212a. In addition, the light incident on the inside from the light incident end surface 212a passes through the light guide plate 210 and is emitted to the outside from the light emission surface 211a by the reflection plate 223 provided so as to cover the back surface of the light guide plate 210.

  On the other hand, light in a direction substantially parallel to the light emitting surface 12a of the LED 12 enters the light incident end surface 212b. Generally, it is difficult to take light in a direction substantially parallel to the light emitting surface into the light guide plate and to emit the light from the light emitting surface, and it is expected that the light from the LED as a light source can be used more efficiently. .

  Therefore, in the light guide plate 210 according to the present embodiment, the inclined surface that forms a pair with the light incident end surface 212 b is the total reflection surface 213. The total reflection surface 213 reflects all the light incident from the light emitting surface 12 a of the LED 12 into the light guide plate 210 without taking it out of the light guide plate 210.

  By the way, in this embodiment, as FIG. 3 shows, 1st surface A1 including the light emission surface 12a of LED12 and 2nd surface A2 including the said total reflection surface 213 cross | intersect on the outer side of the light emission surface 12a. . That is, the notch 210a is formed in the light guide plate 210 so as to satisfy such a condition. Therefore, in the present embodiment, the total reflection surface 213 is disposed on the side of the light emitting surface 12a of the LED 12.

  By forming the notch 210a so as to satisfy the above conditions and disposing the LED 12, light emitted in a direction substantially parallel to the light emitting surface 12a of the LED 12 (first surface direction) is incident on the total reflection surface 213. become.

  Specifically, the inclination angle of the total reflection surface 213 is an angle at which the incident angle θ of the light L1 along the surface direction of the light emitting surface 12a out of the light incident from the light emitting surface 12a of the LED 12 is equal to or greater than the critical angle. Specifically, it is in a state inclined by 45 ° with respect to the light emitting surface 12a. Of the light emitted from the light emitting surface 12a, the light emitted along the surface direction of the light emitting surface 12a (the light L1) has a minimum incident angle, and therefore the light L2 other than the light L1 is totally reflected. It is incident on the surface 213 at a critical angle or more.

  With such a configuration, the light emitted from the light emitting surface 12 a and incident on the light incident end surface 212 b can be totally reflected by the total reflection surface 213 and taken into the light guide plate 210. Therefore, high light utilization efficiency can be obtained by efficiently taking the light emitted from the light emitting surface 12a of the LED 12 into the light guide plate 210.

Hereinafter, the other configurations constituting the liquid crystal device will be described in detail.
(LCD panel)
As shown in FIG. 1, the liquid crystal panel 100 includes a first substrate 3, a second substrate 2 having a projecting portion 2 a that projects from the first substrate 3, and the first substrate 3 and the second substrate 2 are bonded together. A sealing material (not shown) provided at the peripheral edge of the substrate, and a liquid crystal layer (not shown) as an electro-optical material disposed in a space formed by the first substrate 3 and the second substrate 2 and the sealing material, The first polarizing plate 8a and the second polarizing plate 8b are provided so as to sandwich the pair of substrates 2 and 3 therebetween. The first substrate 3 and the second substrate 2 are made of translucent glass, plastic, or the like.

  On the surface of the first substrate 3 facing the second substrate 2, stripe-shaped first transparent electrodes made of a plurality of ITO (Indium / Tin Oxide) films are provided, and polyimide is formed so as to cover the first transparent electrodes. An alignment film made of or the like is formed. On the other hand, on the surface of the second substrate 2 facing the first substrate 3, a stripe-shaped second transparent electrode made of a plurality of ITO films is provided so as to intersect the first transparent electrode. An alignment film made of polyimide or the like is formed so as to cover the surface. Here, the first transparent electrode, the second transparent electrode, and the alignment film covering them are formed by a known technique, and are not shown in FIG.

  On the projecting portion 2a, for example, a driving IC 23 and an input terminal (not shown) necessary for driving the liquid crystal panel 100 are connected, and an external power source and various external devices are connected to the input terminal. As a result, a drive signal and power can be supplied to the liquid crystal panel 100 via the FPC board 10. The FPC board 10 is made of, for example, FPC having excellent flexibility, for example, using a film made of polyimide, polyester, or the like as a base material.

  In the liquid crystal panel 100 having such a configuration, pixels are formed by the first transparent electrode and the second transparent electrode facing each other and the liquid crystal layer sandwiched between them. The optical characteristics of the liquid crystal layer are changed by selectively changing the voltage applied to each pixel, and the light emitted from the backlight 200 is modulated by passing through the liquid crystal layer of each pixel. Thus, by modulating the light, an image or the like can be displayed, and the display area in the liquid crystal panel 100 is substantially equal to the display area V surrounded by the sealing material.

(FPC board for light source)
The light source FPC board 18 is made of, for example, FPC having excellent flexibility with a film made of polyimide, polyester, or the like as a base material. As shown in FIG. 4, one end of the FPC board 18 has an adhesive sheet (not shown). To be attached to the upper surface 301 of the frame 300. Thus, the LED 12 is held in the notch 210a of the light guide plate 210.

(flame)
The frame 300 has a plurality of LED notches 310b in which the LEDs 12 are accommodated. A hole corresponding to the shape of the LED 12 is formed between the LED notch 310 b and the light guide plate 210 fitted in the frame 300. Thus, by providing the LED notch 310b for housing the LED 12 in the frame 300, it is not necessary to provide the LED 12 in a state of protruding from the light guide plate 210, and the liquid crystal device 1 can be downsized.

The effects of the liquid crystal device in this embodiment will be described below.
As described above, in the conventional backlight, the light in the surface direction of the light emitting surface of the LED cannot be taken into the light guide plate, and it is difficult to efficiently use the light of the LED.
On the other hand, the liquid crystal device 1 in the present embodiment can take light emitted in a direction substantially parallel to the light emitting surface 12a of the LED 12 into the light guide plate 210 by the total reflection surface 213, and the light use efficiency in the LED 12 is improved. To do. Therefore, the highly reliable liquid crystal device 1 having excellent display quality can be provided by including the backlight 200 with high light utilization efficiency.

(Other embodiments of liquid crystal device)
Next, another embodiment of the present invention will be described.
As described above, the total reflection surface 213 is such that the light rays of the first surface A1 including the light emission surface 12a of the LED 12 and the second surface A2 including the total reflection surface 213 are positioned outside the light emission surface 12a. For example, the shape is not limited to the above embodiment. That is, since the light guide plate 210 positioned below the light emitting surface 12a of the LED 12 (on the side facing the light emitting surface 12a) does not affect the light capture, as shown in FIG. Thus, the shape of the light guide plate 210 can be reduced compared to the above embodiment. Further, as shown in FIG. 5B, the light emitting surface 12a of the LED 12 is attached to a flat surface provided in the notch portion 210a, and a slope portion forming the total reflection surface 213 is adjacent to the side of the light emitting surface 12a. It is also possible to adopt the structure.

  In the above embodiment, the LED 12 is arranged at a position facing the one end face of the light guide plate 210. However, the LED 12 can be arranged at the corner R of the light guide plate 210 as shown in FIG. . When the light guide plate 210 having a rectangular shape is formed by cutting out a part of the corner portion R to form the notch portion 210a, the two end sides 214 constituting the corner portion R are similar to the configuration shown in FIG. An inclined surface of 45 ° is formed with respect to the light emitting surface 12 a of the LED 12. Therefore, according to this configuration, the light emitted along the surface direction of the light emitting surface 12a of the LED 12 is totally reflected by the two end sides 214 constituting the corner portion R functioning as the total reflection surface 213. It becomes. That is, according to the present configuration, the end side 214 constituting the corner portion R can be used as the total reflection surface 213. Therefore, by cutting out a part of the corner portion R of the light guide plate 210, it is possible to easily improve the light utilization efficiency of the LED 12 at low cost without greatly processing the conventional light guide plate. Also, the configuration shown in FIG. 2 as described above and the configuration shown in FIG. 6 can be combined.

  By the way, since the light emission surface 12a of LED12 is surface emission, it is inject | emitted in all directions along the surface direction of the light emission surface 12a, as shown to Fig.7 (a). Therefore, as shown in FIG. 7B, the light guide plate 210 is provided with a tapered portion 250, a concave portion 251 is formed on the distal end side (side where the inner diameter is narrow) of the tapered portion 250, and the LED 12 is formed in the concave portion 251. It is good also as a structure which has arranged. The taper surface 250a of the taper portion 250 functions as a total reflection surface 213 that enables total reflection of light emitted in the surface direction of the light emitting surface 12a of the LED 12. That is, in the configuration shown in FIG. 7B, the total reflection surface 213 is formed over the entire circumference of the light emitting surface 12 a of the LED 12. Therefore, according to this configuration, light in all directions emitted along the first surface A1 including the light emitting surface 12a of the LED 12 can be taken into the light guide plate 210 by being totally reflected by the tapered surface 250a. The light utilization efficiency in the LED 12 can be further improved.

  Moreover, as shown in FIG. 8, the structure which joined LED12 to the said light-guide plate 210 via the transparent resin 260 is also employable. In FIG. 8, a transparent resin 260 is arranged in the notch 210a of the light guide plate 210 shown in FIG. 2, and the light guide plate 210 is joined to the light emitting surface 12a side of the LED 12 via the transparent resin 260. It has become.

  Here, the transparent resin 260 is made of a material having a refractive index substantially equal to that of the light guide plate 210. As described above, the light guide plate 210 made of acrylic resin (refractive index: about 1.5) is used in the present embodiment. Therefore, in this embodiment, PMMA (polymethyl methacrylate) having a refractive index of 1.49 is used as the transparent resin 260. According to this configuration, the degree of refraction generated at the interface between the light guide plate 210 and the transparent resin 260 when the light L3 emitted from the light emitting surface 12a of the LED 12 passes through the transparent resin 260 is reduced. Therefore, the light use efficiency in LED12 can be improved more by eliminating the loss resulting from refraction.

  The illumination device of the present invention can also be applied to an electrophoretic device as another embodiment of an electro-optical device. The liquid crystal device described above is not limited to a passive type, and can be applied to an active matrix liquid crystal device using a switching element such as a TFT or a TFD.

(Electronics)
Next, the electronic apparatus of the present invention will be described. An electronic apparatus according to the present invention includes the above-described liquid crystal device according to the present invention.
Hereinafter, a mobile phone 90 including the above-described liquid crystal device will be described as an example of an electronic apparatus.
FIG. 9 is a perspective view showing the configuration of the mobile phone 90. As shown in FIG. 9, this cellular phone 90 is provided with a liquid crystal device as a display unit 94 together with a plurality of operation buttons 91, a mouthpiece 92, and a mouthpiece 93.

  According to the mobile phone 90 of the present embodiment, since the liquid crystal device 1 is provided as a display unit as described above, the reliability is high.

  In addition to the mobile phone, the electronic device of the present invention includes, for example, an electronic notebook, a personal computer, an electronic book, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, and a word processor. , Workstations, videophones, POS terminals and the like.

It is a disassembled perspective view of a liquid crystal device. It is a figure which shows the principal part of an illuminating device. It is a figure for demonstrating the principal part of a light-guide plate. It is a figure which shows typically the bonding structure of an illuminating device. (A), (b) is a figure which shows the other structure in a light-guide plate. It is a figure which shows the modification of the arrangement position of LED. It is a figure which shows the structure which concerns on the modification of a light-guide plate. It is a figure which shows the structure which concerns on the modification of a light-guide plate. It is a figure which shows schematic structure of the mobile telephone which concerns on one Embodiment of an electronic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal device (electro-optical device), 12 ... LED (light source), 12a ... Light emission surface, 90 ... Mobile phone (electronic device), 100 ... Light modulation device, 200 ... Backlight (illumination device), 210 ... Light guide plate 210a ... notch (recess), 211a ... light exit surface, 212a ... light incident end surface, 212b ... light incident end surface, 213 ... total reflection surface, 260 ... transparent resin, A1 ... first surface, A2 ... second Surface, R ... Corner

Claims (7)

In an illuminating device comprising a light source and a light guide plate that emits light from the light source from the light incident end surface while being incident from the light incident end surface,
The light guide plate is formed with a concave portion whose inner surface forms the light incident end surface, and the light source is disposed in the concave portion,
An illuminating device characterized in that a total reflection surface that totally reflects and takes in the light in the light guide plate incident from the light incident end surface is provided on the side of the light emitting surface of the light source. .   The lighting device according to claim 1, further comprising a plurality of the light sources, wherein the total reflection surface is provided corresponding to each of the light sources.   The lighting device according to claim 1, wherein the light source is disposed at a corner of the light guide plate.   The lighting device according to claim 1, wherein the total reflection surface is provided over the entire circumference of the light emitting surface of the light source. The light emitting surface side of the light source is joined to the light guide plate via a transparent resin,
The said transparent resin is comprised from the material which has a refractive index substantially equivalent to the said light-guide plate, The illuminating device as described in any one of Claims 1-4 characterized by the above-mentioned.   An electro-optical device comprising: the illumination device according to claim 1; and a light modulation device that modulates light from the illumination device.   An electronic apparatus comprising the electro-optical device according to claim 6.

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