JP2005276753A - Backlight unit, electric optical device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight unit, an electric optical device and an electronic equipment, which can improve the adhesion strength to a light guide plate of a reflecting plate without causing uneven brightness. <P>SOLUTION: The backlight unit of the present invention comprises a plurality of point light sources which emit light, a light guide plate having an incident face on which the light from the point light sources are incident, an emitting face from which the incident light is emitted, and an opposite face which is opposite to the emitting face, and a reflecting member which reflects the light emitted from the opposite face of the light guide plate to the side of the emitting face. The reflecting member and a non-illuminated region on the opposite face, which is a region which resides between the point light sources and on which no light from the point light sources is irradiated are adhered to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a backlight unit, an electro-optical device, and an electronic device, and more particularly, to a backlight unit, an electro-optical device, and an electronic device that have improved adhesive strength between a light guide plate and a reflecting plate.

  In recent years, liquid crystal devices are widely used in electronic devices such as computers and mobile phones. In this liquid crystal device, generally, a liquid crystal is sandwiched between a pair of substrates provided with electrodes, and a voltage is applied between the electrodes to control the orientation of the liquid crystal, thereby modulating light passing through the liquid crystal and displaying an image. I do.

  Differentiating liquid crystal devices based on the way light is supplied to the liquid crystal, a reflective liquid crystal device that reflects external light by a reflector provided on the outer surface or inner surface of one substrate, or provided outside the one substrate A transflective liquid crystal device with a structure that supplies light to the liquid crystal in a planar manner by a lighting device or a transflective device that functions as a reflective type when there is external light and as a transmissive type when external light is insufficient Various liquid crystal devices such as a semi-reflective liquid crystal device are known.

  Conventionally, a light emitting element such as an LED (Light Emitting Diode) is used as a light emitting source as a liquid crystal device that supplies light to liquid crystal using an illumination device such as a transmissive liquid crystal device or a transflective liquid crystal device. Structures are known. The illuminating device of the liquid crystal device mainly includes a light source, a light guide plate, and a reflection plate. When the LED is used for a lighting device of a liquid crystal device, the LED is mounted at a position facing the light guide plate of the FPC connected to the liquid crystal panel, and the other end of the FPC is attached to a reflection plate provided on the lower surface of the light guide plate. A method of attaching is proposed (see, for example, Patent Document 1).

  In the case of a method in which one end of the FPC is attached to the reflecting plate, the reflecting plate may bend due to the weight of the FPC, and luminance unevenness may occur in the illumination light emitted from the light guide plate. In order to prevent the bending of the reflecting plate, the reflecting plate is usually fixed to the light guide plate with a double-sided tape.

JP 2001-330830 A

  However, in order to improve the adhesive strength of the reflector to the light guide plate, in the method of fixing the reflector to the light source side end of the light guide plate with double-sided tape, the light of the light guide plate part to which the double-sided tape is adhered is irradiated. Unnecessary diffusion occurs in the illumination area, and there is a problem that luminance unevenness occurs in which part of the light exit surface shines abnormally brightly.

  The present invention has been made in view of the above, and provides a backlight unit, an electro-optical device, and an electronic apparatus capable of improving the adhesive strength of a reflecting plate to a light guide plate without causing luminance unevenness. For the purpose.

  In order to solve the above-described problems and achieve the object, the present invention provides a plurality of point light sources that emit light, an incident surface on which light from the point light source is incident, and an exit from which incident light is emitted. A light guide plate having a surface and a facing surface facing the light emitting surface, and a reflecting member that reflects light emitted from the facing surface of the light guide plate toward the light emitting surface, The non-illuminated region on the facing surface, which is a region between the regions and is not irradiated with light from the point light source, and the reflecting member are bonded to each other.

  As a result, the non-illuminated area on the opposite surface where the light of the point light source of the light guide plate is not incident and the reflecting member are bonded, so that the light emitted from the point light source is not incident on this non-illuminated area. Also, since the reflected light from the reflecting plate member is not incident, it is possible to supply illumination light with uniform luminance without causing luminance unevenness, and it is possible to firmly fix the reflecting member to the light guide plate. As a result, it is possible to provide a backlight unit capable of improving the adhesive strength of the reflecting plate to the light guide plate without causing uneven brightness.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the non-illumination region is formed in the vicinity of the incident surface. As a result, it is possible to effectively use the non-illuminated region near the incident surface of the light guide plate.

  According to a preferred aspect of the present invention, it is desirable that the reflecting member is bonded with a double-sided tape. Thereby, it becomes possible to adhere the reflecting member to the light guide plate by a low cost and simple method.

  According to a preferred aspect of the present invention, it is desirable that the point light source is an LED. Thereby, it becomes possible to use a low-cost point light source.

  In order to solve the above-described problems and achieve the object, the present invention provides a plurality of point light sources that emit light, an incident surface on which light from the point light source is incident, and an output from which incident light is emitted. A region between the point light sources, comprising: a light guide plate having a surface and an opposing surface facing the output surface; and a reflective member that reflects light emitted from the opposing surface of the light guide plate toward the output surface side. A non-illuminated area on the facing surface, which is an area where the light from the point light source is not irradiated, and the reflecting member, and a display panel for displaying an image, comprising an electro-optic material And a flexible printed circuit board on which the point light source is mounted, and the flexible printed circuit board is mounted on the display panel so that the point light source is disposed at a position facing the incident surface of the light guide plate. Flexi Wherein the one end of the cable printed circuit board is bonded to the reflective member.

  As a result, the non-illuminated area on the opposite surface where the light of the point light source of the light guide plate is not incident and the reflecting member are bonded, so that the light emitted from the point light source is not incident on this non-illuminated area. Also, since the reflected light from the reflecting plate member is not incident, it is possible to supply illumination light with uniform luminance without causing luminance unevenness, and it is possible to firmly fix the reflecting member to the light guide plate. Furthermore, even in the configuration in which the flexible printed board is fixed to the reflecting plate, since the adhesive strength of the reflecting plate to the light guide plate is improved, the reflecting plate does not bend and brightness unevenness due to the bending of the reflecting plate is prevented. And high-quality image display can be performed. As a result, it is possible to provide an electro-optical device capable of improving the adhesive strength of the reflecting plate to the light guide plate without causing uneven brightness.

  Further, according to a preferred aspect of the present invention, at least a part of an ineffective display area that is an area on the facing surface of the light guide plate and does not overlap with an effective display area of the display panel, and the reflecting member It is desirable that they are bonded. Thereby, it becomes possible to improve the adhesive strength of the reflection member with respect to the light guide plate.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the other end side of the one end side of the flexible printed board is fixed to the display panel. Thereby, even in the case of a method in which the flexible printed circuit board is bent and used, it is possible to prevent luminance unevenness due to bending of the reflecting plate.

  According to a preferred aspect of the present invention, it is desirable that the electronic apparatus is equipped with the electro-optical device of the present invention. As a result, it is possible to provide an electronic device capable of performing high-quality image display without luminance unevenness.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same. In the following embodiments, a liquid crystal display device will be described as an example of an electro-optical device, but the present invention is not limited to this.

  FIG. 1 is a diagram illustrating a configuration example of an electro-optical device 1 according to a first embodiment of the invention, FIG. 1-1 is a perspective view of the electro-optical device 1 according to the first embodiment, and FIG. 1 is a cross-sectional view taken along line AA of FIG.

  As shown in FIG. 1, the electro-optical device 1 guides incident light from a liquid crystal display panel 10 for displaying an image, a polarizing plate 20 and a polarizing plate 30 attached to the liquid crystal display panel 10, and an LED 60. A light guide plate 40, a reflective plate 50 that reflects light emitted from the light guide plate 40 toward the display surface side, a plurality of LEDs 60 that are light sources, a driver IC 70 that is COG mounted on the display substrate 10 b of the liquid crystal display panel 10, An FPC (Flexible Printed Circuits) 80 that is routed from the display substrate 10b of the liquid crystal display panel 10 to the back surface side of the reflector 50 and is mounted so that the LED 60 is disposed on the side surface of the light guide plate 40 is made of plastic, for example. It is configured to be housed in a frame (housing) 90 having a frame shape.

  The liquid crystal display panel 10 is configured by enclosing a liquid crystal between two display substrates 10a and 10b arranged to face each other. The display substrate 10a and the display substrate 10b are made of glass. On the display substrate 10a, a color filter (not shown), a first electrode formed of an ITO film, an alignment film, and the like are formed. On the display substrate 10b, a switching element (not shown) such as a TFD or a TFT, a second electrode formed of an ITO film, an alignment film, and the like are formed. Further, the display substrate 10b has a protruding portion 10b1 that protrudes in a plane in the Y-axis direction from the display substrate 10a.

  A driver IC 70 for driving the liquid crystal display panel 10 is COG mounted on the surface of the protruding portion 10b1, and a signal is supplied to the driver IC 70 and the LED 60 at the surface end portion of the protruding portion 10b1. The FPC 80 is mounted with ACF or the like. Note that the driver IC 70 is not limited to the configuration in which the COG is mounted, and a COF structure (Chip On Film) mounted in the FPC 80 may be adopted. The FPC 80 is bent inward, and one end of the FPC 80 is fixed to the reflecting plate 50 with a double-sided tape (adhesive means) 81.

  In this liquid crystal display panel 10, an electric field is formed by applying an electric charge between the first electrode and the second electrode formed on the two display substrates 10 a and 10 b arranged opposite to each other, and the color filter is formed. The pixel is turned on / off by changing the orientation of the liquid crystal at the corresponding position.

  The display substrate 10a and the back surface of the display substrate 10b (light emission side and light incident side) have liquid crystal types to be used, that is, TN (twisted nematic) mode, STN (super TN) mode, D-STN ( The polarizing plate 20 and the polarizing plate 30 are pasted and arranged in a predetermined direction according to the operation mode such as the double-STN mode or the normally white mode / normally black mode.

  The polarizing plate 20 and the polarizing plate 30 stretch a polyvinyl alcohol (PVA) film in one direction and immerse it in a solution containing iodine or dichroic dye, thereby adsorbing iodine or dichroic dye and providing a deflection function. Further, it is produced by coating a cellulose film as a protective film. Moreover, the polarization direction of the polarizing plate 20 and the polarizing plate 30 is determined by the extending direction of the PVA film.

  A backlight unit is disposed on the side of the polarizing plate 30 opposite to the liquid crystal display panel 10. The backlight unit includes an LED 60 having a light exit surface 61 facing the side end surface of the light guide plate 40, a light guide plate 40 that guides light of the LED 60 from the side end surface, and a light guide plate 40. The reflection plate 50 is disposed on the side opposite to the polarizing plate 30 and reflects light emitted from the light guide plate 40 toward the display surface. The reflection plate 50 is fixed to the light guide plate 40 with a double-sided tape (adhesive means) 51. Further, the backlight unit is provided with a diffusion sheet for diffusing the light emitted from the light guide plate 40 and a prism sheet for polarizing the light diffused by the diffusion sheet on the surface of the light guide plate 40 as necessary. Anyway.

  Next, the light guide plate 40 will be described in detail with reference to FIG. FIG. 2A is a perspective view of the light guide plate 40, and FIG. 2B is a diagram for explaining the facing surface 43 of the light guide plate 40. In FIG. 2B, a part of the optical path of the emitted light from the LED 60 is indicated by a broken line S. The light guide plate 40 is made of a translucent material, and as shown in FIG. 2, the incident surface 41 that is a side end surface on which the light emitted from the LED 60 is incident, and the light incident from the incident surface 41 to the outside of the light guide plate An exit surface 42 that emits light and an opposing surface 43 that faces the exit surface 42 are provided. The other three surfaces are reflective surfaces so that incident light does not leak, and a reflective material is provided as necessary.

  The LED 60 is disposed opposite to the incident surface 41 side. In addition, the opposing surface 43 is a double-sided tape in a non-illuminated region (non-incident region) that is a region between the LEDs 60 in the vicinity of the incident surface 41 and is a blind spot region where the light emitted from the LEDs 60 is not irradiated. A fixing region 40 </ b> A for fixing the reflecting plate 50 by sticking 51 is formed. The reflecting plate 50 returns the light leaking from the facing surface 43 into the light guide plate 40 again.

  The reflection plate 50 is fixed to the light guide plate 40 by adhering the double-sided tape 51 to the fixed region 40 </ b> A and further adhering the double-sided tape 51 and the end of the reflection plate 50. The double-sided tape 51 may be attached to a region corresponding to the fixed region 40 </ b> A of the light guide plate 40 of the reflection plate 50 and then attached to the light guide plate 40.

  In the light guide plate 40 configured as described above, the light from the LED 60 enters the light guide plate 40 from the incident surface 41. The incident light propagates in the light guide plate 40, directly or exits from the facing surface 43, is reflected by the reflecting plate 50, enters the light guide plate 40 again, and exits from the exit surface 42. In this case, the double-sided tape 51 is attached to the fixed region 40A of the light guide plate 40. However, the light emitted from the LED 60 is not incident on the fixed region 40A, and the light reflected by the reflector 50 is not incident. It is possible to firmly fix the reflecting plate 50 to the light guide plate 40 without causing unevenness. Thereby, even in the configuration in which the FPC 80 is fixed to the reflecting plate 50 with the double-sided tape 51, the reflecting plate 50 is not bent due to the weight of the FPC 80, and luminance unevenness caused by the reflecting plate 50 being bent can be prevented. Can do.

  In this embodiment, the double-sided tape is used as the bonding means, but an adhesive or the like as another bonding means may be used.

  In the second embodiment, the reflection plate 50 is fixed to an ineffective display area that does not overlap the display area of the liquid crystal display panel 10 and does not contribute to the display at the end of the light guide plate 40 other than the incident surface 41. This is a configuration in which a second fixed region 40B is formed. FIG. 3 is a diagram for explaining the configuration of the light guide plate 40 according to the second embodiment. As shown in FIG. 3, the light guide plate 40 is formed with a second fixed region 40B in the ineffective display areas at both ends of the light guide plate 40, and a double-sided tape 51 is attached to the second fixed region 40B. Fix it. In this way, by sticking the double-sided tape 51 to at least a part of the ineffective display area of the light guide plate 40 and sticking the reflection plate 50, the light guide plate 40 of the reflection plate 50 is further produced without causing luminance unevenness. It becomes possible to improve the adhesive strength with respect to.

  In addition, this invention is not limited to the said Example, It can implement combining the said Example.

(Application example to electronic equipment)
Next, a specific example of an electronic apparatus to which the electro-optical device according to the invention can be applied will be described with reference to FIG. FIG. 4A is a perspective view illustrating an example in which the electro-optical device according to the present invention is applied to a display unit of a portable personal computer (so-called notebook personal computer) 100. As shown in the figure, the personal computer 100 includes a main body 102 having a keyboard 101 and a display unit 103 to which the electro-optical device according to the invention is applied. FIG. 4B is a perspective view illustrating an example in which the electro-optical device according to the invention is applied to the display unit of the mobile phone 200. As shown in the figure, the mobile phone 200 includes a plurality of operation buttons 201, a receiving mouth 202, a mouthpiece 203, and a display unit 204 to which the electro-optical device according to the invention is applied.

  The electro-optical device according to the present invention can be used for transmissive, reflective, and transflective electro-optical devices. The electro-optical device according to the present invention is applied to a passive matrix type electro-optical device or an active matrix type electro-optical device (for example, an electro-optical panel including a TFT (thin film transistor) or a TFD (thin film diode) as a switching element). Can be used. Furthermore, the electro-optical device according to the present invention is not limited to a liquid crystal display device, but is an organic electroluminescence device, an inorganic electroluminescence device, a plasma display device, an electrophoretic display device, an electron emission display device (Field Emission Display and Surface-Conduction Electoron). -Emitter Display etc.), LED (Light Emitting Diode) display devices, etc., and can be used for various electro-optical devices that can control the display state for each of a plurality of pixels.

  An electronic device equipped with the electro-optical device according to the present invention includes a mobile phone, a portable information device called PDA (Personal Digital Assistants), a portable personal computer, a personal computer, a workstation, a digital still camera, an in-vehicle monitor, a digital Widely used in electronic devices such as video cameras, LCD TVs, viewfinder type, monitor direct-view type video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations, video phones, and POS terminals. Can do.

1 is a perspective view of an electro-optical device according to Embodiment 1. FIG. 1 is a cross-sectional view of an electro-optical device according to Embodiment 1. FIG. 1 is a perspective view of a light guide plate according to Embodiment 1. FIG. FIG. 3 is a diagram for explaining the back surface of the light guide plate according to the first embodiment. FIG. 10 is a diagram for explaining the back surface of the light guide plate according to the second embodiment. 1 is a perspective view of a personal computer equipped with an electro-optical device according to an embodiment. 1 is a perspective view of a mobile phone including an electro-optical device according to an example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electro-optical device, 10 Liquid crystal display panel, 10a Display substrate, 10b Display substrate, 20 Polarizing plate, 30 Polarizing plate, 40 Light guide plate, 40A Fixed area | region, 40B 2nd fixed area | region, 41 Incident surface, 42 Output surface, 43 Opposite Surface, 50 reflector, 51 double-sided tape, 60 LED, 70 driver IC, 80 FPC, 81 double-sided tape, 90 frame, 100 personal computer, 101 keyboard, 102 main body, 103 display, 200 mobile phone, 201 operation buttons, 202 Earpiece, 203 Mouthpiece, 204 Display

Claims (8)

A plurality of point light sources that emit light;
A light guide plate having an incident surface on which light from the point light source is incident, an exit surface from which incident light is emitted, and an opposing surface facing the exit surface;
A reflecting member that reflects light emitted from the facing surface of the light guide plate to the emitting surface side;
With
The backlight unit, characterized in that a non-illuminated region on the facing surface, which is a region between the point light sources and is not irradiated with light from the point light source, and the reflecting member are bonded.   The backlight unit according to claim 1, wherein the non-illumination region is formed in the vicinity of the incident surface.   The backlight unit according to claim 1, wherein the reflecting member is bonded with a double-sided tape.   The said point light source is LED, The backlight unit as described in any one of Claims 1-3 characterized by the above-mentioned. A light guide plate having a plurality of point light sources for emitting light, an incident surface on which light from the point light source is incident, an emission surface from which incident light is emitted, and a facing surface facing the emission surface; A reflecting member that reflects light emitted from the facing surface of the light plate to the emitting surface side, on the facing surface that is a region between the point light sources and is not irradiated with light from the point light source A backlight unit in which the non-illuminated region and the reflective member are bonded,
A display panel with an electro-optic material for displaying images;
A flexible printed circuit board on which the point light source is mounted;
The flexible printed circuit board is mounted on the display panel so that the point light source is disposed at a position facing the incident surface of the light guide plate, and one end side of the flexible printed circuit board is bonded to the reflecting member. An electro-optical device.   The reflective member is bonded to at least a part of a non-effective display area that is an area that does not overlap an effective display area of the display panel and is on the facing surface of the light guide plate. 5. The electro-optical device according to 5.   6. The electro-optical device according to claim 5, wherein the other end side of the one end side of the flexible printed board is fixed to the display panel.   An electronic apparatus comprising the electro-optical device according to any one of claims 5 to 7.

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