JP2006084757A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device whose picture frame is made narrow and the bright linear emission produced in the vicinity of an edge portion of an effective display area is simply prevented at a low cost. <P>SOLUTION: A reflection sheet 8 is formed to be longer than a light guide plate 9 along a direction toward a backlight light source 12 and a bent portion 13 is formed along an inner face of a resin frame 6. The bent portion 13 is arranged so as to make an opening portion 13a oriented to an end face 9a direction and so as to contain the backlight light source 12, reflects light from the backlight light source 12 to a direction toward the light guide plate 9 and the end face 9a of the light guide plate 9 is efficiently irradiated with the light. The tip of the bent portion 13 is bent in a downward direction in the vicinity of the effective display area 3a to form a light controlling piece 15 which is fixed to a notch portion 16 arranged on the end face 9a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to prevention of bright lines generated near a light source in an effective display area of a liquid crystal panel.

  In recent years, so-called flat panel displays have become the mainstream in place of cathode ray tubes that have been conventionally used as display devices, and the market is expanding. Among these, a liquid crystal display (Liquid Crystal Display) is characterized by thinness, light weight, low power consumption, and high definition, and is used in a wide range of fields such as televisions, personal computers, digital cameras, and mobile phones.

  The liquid crystal display device includes a liquid crystal module including a liquid crystal panel and a polarizing plate in which liquid crystal is sealed between a pair of opposed electrode substrates, a backlight device that illuminates the liquid crystal module from the back surface, and various types of devices used for driving the liquid crystal module. Circuit board. The configuration of such a liquid crystal display device is shown in FIG. Reference numeral 1 denotes a front frame, which is combined with the back case 2 to constitute a casing of the liquid crystal display device. The front frame 1 and the back case 2 are formed of a metal such as iron, aluminum, stainless steel, or a hard resin such as ABS resin or polycarbonate.

  Fixing means such as fitting claws and fitting holes, or screw holes (both not shown) are provided at corresponding portions of the front frame 1 and the back case 2, and the liquid crystal stored in the back case 2 Each component of the module is sandwiched with moderate pressure and supported so as not to be detached from the back case 2, and each component is protected from shocks such as vibration and dropping. The front frame 1 is formed in a frame shape, and an effective display area 3a of a liquid crystal panel 3 described later is exposed from a central window portion 1a.

  The liquid crystal panel 3 includes a TFT substrate, a liquid crystal, and a color filter substrate (not shown). The liquid crystal panel 3 includes an effective display area 3a for displaying a desired image and a frame portion 3b around the effective display area 3a. Two driver ICs 4 for driving and controlling the liquid crystal panel 3 are provided on one side of the frame portion 3b. One is provided. Reference numeral 5 denotes a flexible circuit board FPC (Flexible Printed Circuit) in which a circuit is formed on a film of polyester (PET) or the like by printing or etching. A control signal for controlling the liquid crystal panel 3 is transmitted to the driver IC 4 via the FPC 5.

  Reference numeral 6 denotes a resin frame that supports the liquid crystal panel 3. A double-sided adhesive liquid crystal panel fixing tape 7 is provided between the liquid crystal panel 3 and the resin frame 6 to fix the liquid crystal panel 3 and the resin frame 6 together. On the opposite side of the liquid crystal panel 3 across the resin frame 6, a reflection sheet 8, a light guide plate 9, a diffusion sheet 10, and two light collecting sheets (prism sheets) 11a and 11b are arranged on the bottom surface of the back case 2 in this order. Are stacked. Reference numeral 12 denotes a backlight light source composed of a cold cathode fluorescent lamp (CCFL) or the like, which is disposed adjacent to one end of the light guide plate 9. Note that description of cables, connectors, and the like connected to the backlight light source 12 is omitted.

  The reflective sheet 8 is formed by laminating a flexible white resin sheet alone or a reflective layer having a high reflectivity on which silver, aluminum, or the like is deposited, and transmits light from the light guide plate 9 described later in the direction of the liquid crystal panel 3. Reflects efficiently. The light guide plate 9 is a wedge-shaped or parallel plate-shaped plate formed of an acrylic resin or the like, and is laminated on the upper surface of the reflection sheet 8 and has an optical path of light having an optical distribution in the form of a linear light source generated by the backlight light source 12. The light is changed and converted into light having an optical distribution in the form of a surface light source. The diffusion sheet 10 has fine irregularities formed on one side, and randomizes the light emitted from the light guide plate 9. The upper surfaces of the condensing sheets 11a and 11b are prism surfaces, and the luminance in the direction of the liquid crystal panel 3 is improved.

  8 is a cross-sectional view of the liquid crystal display device shown in FIG. 7 in the vicinity of the backlight light source (cross-section AA ′ in FIG. 6). As shown in the figure, a diffusion sheet 10 and two condensing sheets 11 a and 11 b are laminated on the upper surface of the light guide plate 9. The diffusion sheet 10 and the light collecting sheets 11a and 11b constitute an optical sheet, and make the luminance distribution of the light guided by the light guide plate 9 uniform. In this example, one diffusion sheet 10 and two condensing sheets 11a and 11b are used as optical sheets. However, the number and configuration of optical sheets can be appropriately set according to the purpose and application.

  A reflection sheet 8 that reflects light upward is laminated on the lower surface of the light guide plate 9, and a backlight light source 12 is disposed on one end surface 9 a side of the light guide plate 9. Here, the reflection sheet 8, the light guide plate 9, the diffusion sheet 10, the light collecting sheets 11 a and 11 b, and the backlight light source 12 constitute a backlight device for irradiating the liquid crystal panel 3 with light.

  The reflection sheet 8 is formed longer in the direction of the backlight light source 12 than the light guide plate 9, and a U-shaped bent portion 13 is formed along the inner surface of the resin frame 6. The tip of the bent portion 13 is fixed to the upper surface of the light guide plate 9 by a reflection sheet fixing tape 14. With this configuration, the bent portion 13 is arranged so as to include the backlight light source 12 with the opening portion 13a facing the end surface 9a (the direction of arrow A in the figure), and reflects the light from the backlight light source 12. The end surface 9a of the light guide plate 9 is efficiently irradiated as a reflector.

  The light that has entered the light guide plate 9 from the end face 9 a reaches every corner while repeating irregular reflection in the light guide plate 9, and is reflected upward by the reflection sheet 8 laminated on the lower surface of the light guide plate 9. It is injected from the upper surface of The emitted light further sequentially passes through the diffusion sheet 10 and the light collecting sheets 11a and 11b, and uniformly irradiates the effective display area 3a of the liquid crystal panel 3 from behind.

  In such a liquid crystal display device, the light B emitted from the backlight light source 12 in the direction of the edge 3c of the effective display area 3a is reflected in the direction of the light guide plate 9 with the light amount reduced by the reflecting sheet fixing tape 14. . In addition, when the width of the frame portion 3b of the liquid crystal panel 3 is wide, the amount of light that directly enters the vicinity of the edge portion 3c from the backlight source 12 is also reduced. Therefore, there is a problem that the luminance near the edge portion 3c is lowered and the display quality of the liquid crystal panel 3 is lowered.

  In addition, with the demand for further downsizing and larger screens of devices equipped with liquid crystal display devices, liquid crystal display devices tend to be narrowed more and more, but when liquid crystal display devices are narrowed As shown in FIG. 9, the light C emitted from the backlight source 12 near the edge portion 3 c or the light D reflected near the rear edge portion 3 c reflected from the bottom surface of the bent portion 13 is reflected on the reflection sheet 8. Is applied to the light uniformly irradiated upward.

  Since these light beams C and D have a small incident angle to the end surface 9a and are emitted from the surface of the light guide plate 9 without being irregularly reflected inside the light guide plate 9, they are directly incident on the vicinity of the edge portion 3c. The amount of light incident in the vicinity is greater than in other parts. As a result, bright lines that emit light in a bright line shape are generated near the edge portion 3c of the effective display area 3a, and the display quality of the effective display area 3a is lowered.

  Therefore, various methods for preventing the generation of bright lines by suppressing the amount of light that directly enters the vicinity of the edge portion 3c have been proposed. Patent Document 1 opens in the direction of the end face of the light guide plate and encloses the backlight light source. A method of controlling the light emission direction of the backlight light source by the resin-made reflecting members arranged in this manner is disclosed. Patent Document 2 discloses a method of reducing the amount of incident light by projecting a part of a light guide plate in the direction of the backlight light source and providing a light shielding film on the projecting part.

  Further, in Patent Document 3, a front end portion of a reflecting member that guides light from a light source to a side surface of a light guide plate is bent to form an abutting surface, and this is applied to an incident surface of the light guide plate using an urging force of an elastic member. A method is disclosed in which the generation of bright lines is suppressed by abutting to prevent light from entering the light guide plate from the light-emitting side edge of the light guide plate.

  However, the methods disclosed in Patent Documents 1 and 3 require a reflecting member whose inner surface is subjected to reflection processing in addition to the reflecting sheet, which increases the number of assembly steps and the number of parts, leading to an increase in the cost of the liquid crystal display device. On the other hand, in the method of Patent Document 2, although the generation of bright lines can be prevented, the shape of the light guide plate is complicated, and the light use efficiency is lowered by the light shielding film, so that the display becomes dark.

In addition, the method of Patent Document 3 prevents light from being incident from the output side edge of the light guide plate because the abutting surface is not easily deformed when the reflecting member is made of a rigid material such as metal. However, as shown in FIG. 8, when the reflective sheet is also used as a reflective member by forming a bent portion by bending the flexible reflective sheet, light leakage due to deformation of the abutting surface may occur. There is a problem that the generation of bright lines cannot be reliably prevented.
Japanese Patent Laid-Open No. 10-172323 JP-A-10-253958 JP 2001-118417 A

  In view of the above problems, an object of the present invention is to provide a liquid crystal display device that realizes a narrow frame and prevents the generation of bright lines near the edge portion of an effective display area easily and at low cost.

  In order to achieve the above object, the present invention provides a backlight light source, a light guide plate disposed at one end adjacent to the backlight light source, a light source plate laminated on the lower surface of the light guide plate, and capable of reflecting light upward. A flexible reflective sheet, and a bent portion that extends from one end of the reflective sheet to enclose the backlight light source and guides light emitted from the backlight light source toward the light guide plate. And a liquid crystal panel in which liquid crystal is sealed between a pair of opposed electrode substrates, and the backlight device irradiates the liquid crystal panel from the back to display an image. A light control piece for controlling the light emitted from the backlight light source to be incident on the end of the light guide plate by bending the tip of the bent portion downward, and the light control It is characterized in that fixed to the end face or in the vicinity adjacent to the backlight source of the light guide plate.

  According to the present invention, in the liquid crystal display device configured as described above, the light control piece is provided in the vicinity of the outside of the effective display area of the liquid crystal panel.

  According to the present invention, in the liquid crystal display device having the above-described configuration, a cut portion for fixing the light control piece is provided on an end surface of the light guide plate adjacent to the backlight light source.

  According to the present invention, in the liquid crystal display device configured as described above, the light control piece is inserted into a cut portion provided on an upper surface of the light guide plate.

  According to the first configuration of the present invention, the light control piece is provided by bending one end of the flexible reflecting sheet downward and bending the tip of the bent portion formed so as to contain the backlight light source. Therefore, the amount of light that directly enters the vicinity of the edge of the liquid crystal panel from the backlight light source can be suppressed, and even in a liquid crystal display device with a narrow frame, generation of bright lines is prevented and light reflected by the light control piece is bent. The light utilization efficiency does not decrease because the light is reflected and reused. Further, since the light control piece is formed by a part of the reflection sheet, a member for suppressing the amount of light is not required separately, and the cost of the apparatus can be reduced. Furthermore, since the light control piece is fixed to the end face of the light guide plate adjacent to the backlight light source or in the vicinity thereof, light leakage caused by deformation of the light control piece even if the light control piece is formed of a flexible reflective sheet. Does not occur.

  According to the second configuration of the present invention, in the liquid crystal display device of the first configuration, the light control piece is provided in the vicinity of the outside of the effective display area of the liquid crystal panel, so that the vicinity of the edge portion of the liquid crystal panel. It is possible to effectively reduce unnecessary light that is directly incident and obtain a more uniform luminance distribution on the backlight surface.

  According to the third configuration of the present invention, in the liquid crystal display device having the first or second configuration, a notch for fixing the light control piece is provided on the end surface of the light guide plate adjacent to the backlight light source. This facilitates the positioning of the light control piece with respect to the light guide plate in the vertical direction, and the effect of suppressing the amount of light is further ensured.

  Further, according to the fourth configuration of the present invention, in the liquid crystal display device having the first or second configuration, the light control piece is inserted into the cut portion provided on the upper surface of the light guide plate, thereby fixing the reflection sheet. The light control piece can be reliably fixed without using an adhesive tape or an adhesive.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a structure near a backlight source of a liquid crystal display device according to a first embodiment of the present invention. Portions common to FIGS. 8 and 9 of the conventional example are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the tip of the bent portion 13 is bent downward near the edge portion 3c of the effective display area 3a to form the light control piece 15.

  FIG. 2 is an enlarged cross-sectional view around the bent portion 13 in FIG. The end face 9 a of the light guide plate 9 is continuously provided with a cut portion 16 along the paper surface direction of the drawing, and the light control piece 15 is fixed to the cut portion 16 with a reflection sheet fixing tape 14. The light L emitted from the backlight source 12 in the direction of the edge portion 3c is sequentially reflected by the inner surface 15a of the light control piece 15 and the inner surfaces 13b, 13c, and 13d of the bent portion 13, and then the light guide plate 9 from the opening portion 13a. Incident in.

  With this configuration, the light emitted from the backlight light source 12 in the direction of the edge portion 3c is blocked by the light control piece 15 to reduce the amount of light directly incident on the vicinity of the edge portion 3c of the liquid crystal panel, and from the opening portion 13a to the light guide plate. The light that has entered inside 9 reaches the end face (not shown) on the side opposite to the end face 9a (the left side in the figure) while repeating irregular reflection inside, effectively preventing the generation of bright lines and irradiating the effective display area 3a uniformly. can do.

  Further, since the light reflected by the light control piece 15 is reused via the bent portion 13, the use efficiency of the light emitted from the backlight light source 12 does not decrease, and the display due to the decrease in luminance of the liquid crystal display device There is no risk of degradation. Further, since the light control piece 15 is formed by bending the tip of the bent portion 13, that is, one end of the reflection sheet 8, there is no need to separately attach a member for suppressing the amount of light, and the apparatus can be reduced by reducing the number of parts and the number of assembly steps. Cost reduction is possible.

  Since the luminance near the edge portion 3c of the effective display area 3a is too bright (too bright), the light control is performed by sending light farther and lowering the luminance near the edge portion 3c. There is an effect that the luminance distribution of the light surface can be obtained. Therefore, it is desirable to provide the light control piece 15 near the outside of the effective display area 3a as in the present embodiment, and to control the amount of light directly incident on the vicinity of the edge portion 3c to reduce the luminance near the edge portion 3c.

  The amount of downward projection of the light control piece 15 is not particularly limited as long as it is a size that can prevent light from entering the light guide plate 9 from the output side edge of the end face 9a, but is about 1 to 1.5 mm. Is preferred. Since the light control piece 15 is formed by using a part of the reflection sheet 8, the protruding amount of the light control piece 15 can be freely changed only by changing the size of the reflection sheet 8. Therefore, it is not necessary to prepare many kinds of members for suppressing the amount of light according to variations of the liquid crystal display device. Here, since the light control piece 15 is fixed along the notch 16, the light control piece 15 can be easily positioned in the vertical direction, and the protruding amount of the light control piece 15 is always constant with respect to the thickness of the light guide plate 9. Regulated by quantity.

  Further, since the light control piece 15 is formed by bending the flexible reflection sheet 8, if the light control piece 15 is deformed by the restoring force of the reflection sheet 8 or the like, the light control effect may vary. Therefore, it is necessary to fix the light control piece 15 to another member to prevent deformation. As a method for fixing the light control piece 15, in addition to using the double-sided adhesive reflecting sheet fixing tape 14 as described above, a method using an adhesive or a method such as screwing can be arbitrarily selected. In view of cost and cost, fixing with an adhesive tape is preferable.

  FIG. 3 is a partial cross-sectional view showing the structure near the backlight source of the liquid crystal display device according to the second embodiment of the present invention. Portions common to FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In this embodiment, the notch 16 is not provided in the end surface 9 a of the light guide plate 9, and the light control piece 15 is fixed to the end surface 9 a via the reflection sheet fixing tape 14.

  Also in this embodiment, similarly to the first embodiment, the light control piece 15 can suppress the amount of light incident near the edge portion 3c and effectively prevent the bright line from being generated. Furthermore, since the notch 16 is not provided in the end surface 9a, the manufacturing process of the light guide plate 9 is further simplified as compared with the first embodiment. Since the position and fixing method for providing the light control piece 15 are the same as those in the first embodiment, description thereof is omitted.

  FIG. 4 is a partial cross-sectional view showing the structure near the backlight source of the liquid crystal display device according to the third embodiment of the present invention. Portions common to FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, the cut portion 16 is provided in a groove shape continuously along the plane of the drawing in the position of the upper surface 9b of the light guide plate 9 facing the edge portion 3c, and the light control piece 15 is cut. It is inserted into the part 16.

  At this time, by setting the gap of the cut portion 16 to be equal to or slightly wider than the thickness of the reflection sheet 8, the light control piece 15 can be securely fixed to the light guide plate 9 simply by inserting the light control piece 15 into the cut portion 16. This eliminates the need to use a reflective sheet fixing tape or adhesive. Note that the position where the light control piece 15 is provided is preferably the edge portion 3c as in the first and second embodiments.

  In each of the above embodiments, the light control piece 15 is fixed to the light guide plate 9. However, as shown in FIG. 5, for example, the protrusion 6 a is integrally formed with the resin frame 6, and the light control piece is formed. It is also possible to fix 15 to the protrusion 6a. However, when directly fixed to the light guide plate 9 as in each of the above embodiments, the light control piece 15 can be fixed without complicating the shape of the resin frame 6, and the light guide plate 9 is displaced or temperature is affected by vibration or impact. Even when thermal deformation of the light guide plate 9 due to the change occurs, it is more preferable because no gap is generated between the light control piece 15 and the light guide plate 9.

  Also, the shape of the bent portion 13 is not limited to the U-shaped cross section as shown in each embodiment as long as the shape includes the backlight light source 12. For example, the cross section as shown in FIG. It may be U-shaped. In this case, the inner surface of the back case 2 is formed in a U-shape, and the reflection sheet 8 is bent along the inner surface of the back case 2 to form the bent portion 13.

  In addition, this invention is not limited to said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the surface of the reflection sheet 8 facing the light guide plate 9 may be subjected to dot printing for light diffusion or embossing. In the above embodiments, only the configuration in which the backlight light source 12 is disposed on one end surface of the light guide plate 9 has been described. However, the present invention can be applied to a case where the backlight light source 12 is disposed on a plurality of end surfaces of the light guide plate 9. By mounting the liquid crystal display device of the present invention on a liquid crystal television, a personal computer, a digital camera, etc., a liquid crystal display device that prevents generation of bright lines in the vicinity of the edge portion without increasing the width of the frame portion of the liquid crystal display portion is provided. It can be provided and contributes to the high quality and large screen of each product equipped with a liquid crystal display device, which has been strongly demanded in recent years.

  The present invention comprises a backlight light source, a light guide plate disposed adjacent to the backlight light source, a flexible reflective sheet that is laminated on the lower surface of the light guide plate and reflects light upward, One end of the reflection sheet is extended to include the backlight light source, and the backlight device includes a bent portion that guides the light emitted from the backlight light source in the direction of the light guide plate, and a pair of opposed backlight devices In a liquid crystal display device for displaying an image by irradiating the liquid crystal panel from the back with a backlight device, by bending the front end of the bent portion downward A light control piece that controls the incidence of light emitted from the backlight light source to the end of the light guide plate is provided, and the light control piece is at or near the end face of the light guide plate adjacent to the backlight light source. To be fixed.

  As a result, even in a narrow frame liquid crystal display device, the amount of light directly incident on the edge portion is effectively suppressed by the light control piece, and the light reflected by the light control piece is reused. Therefore, it is possible to provide a high-quality liquid crystal display device that does not generate the luminance and does not reduce the luminance of the display device. Moreover, even if the reflection sheet has flexibility, the light control piece can be fixed easily and reliably, and fluctuations in the light amount suppression effect due to deformation of the light control piece can be prevented. Further, since the light control piece is formed by a part of the reflection sheet, a member for suppressing the amount of light is not required separately, which contributes to cost reduction of the liquid crystal display device.

  In addition, since the light control piece is provided near the outside of the effective display area of the liquid crystal panel, only unnecessary light that directly enters the vicinity of the edge of the liquid crystal panel can be reduced, and the liquid crystal is generated along with the generation of bright lines near the edge. A luminance reduction of the display device is more effectively prevented, and a uniform luminance distribution on the backlight surface is realized.

  Further, if a notch for fixing the light control piece is provided on the end face of the light guide plate adjacent to the backlight light source and the light control piece is fixed along the notch, the vertical positioning of the light control piece with respect to the light guide plate is further enhanced. It becomes easy.

  In addition, by inserting the light control piece into the cut portion provided on the upper surface of the light guide plate, the light control piece can be securely fixed without using a separate fixing member.

These are the fragmentary sectional views of the backlight light source vicinity of the liquid crystal display device which concerns on 1st Embodiment of this invention. These are the expanded sectional views of the bent part periphery in the liquid crystal display device of 1st Embodiment. These are the fragmentary sectional views of the backlight light source vicinity of the liquid crystal display device which concerns on 2nd Embodiment of this invention. These are the fragmentary sectional views of the backlight light source vicinity of the liquid crystal display device which concerns on 3rd Embodiment of this invention. These are the fragmentary sectional views which show the example which fixed the light control piece to the resin frame. These are the fragmentary sectional views which show the example which made the bending part into another shape. These are exploded perspective views showing a configuration of a conventional liquid crystal display device. These are the fragmentary sectional views of the backlight light source vicinity in the conventional liquid crystal display device. These are the fragmentary sectional views which show the other example of the backlight light source vicinity in the conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front frame 2 Back case 3 Liquid crystal panel 3a Effective display area 3b Frame part 3c Edge part 6 Resin frame 8 Reflective sheet 9 Light guide plate 10 Diffusion sheet 11a, 11b Condensing sheet 12 Backlight source 13 Bending part 14 Reflecting sheet fixation Tape 15 Light control piece 16 Notch

Claims (4)

A backlight source, a light guide plate disposed adjacent to the backlight source, a flexible reflection sheet that is laminated on the lower surface of the light guide plate and reflects light upward, and A backlight device comprising: a bent portion formed to extend one end to include the backlight light source and guide light emitted from the backlight light source toward the light guide plate;
A liquid crystal panel formed by enclosing a liquid crystal between a pair of opposing electrode substrates,
In the liquid crystal display device that performs image display by irradiating the liquid crystal panel from the back by the backlight device,
A light control piece is provided for controlling the light emitted from the backlight light source to enter the light guide plate end by bending the tip of the bent part downward, and the light control piece is provided with the light guide piece. A liquid crystal display device, wherein the liquid crystal display device is fixed to an end face of the light plate adjacent to the backlight source or in the vicinity thereof.   The liquid crystal display device according to claim 1, wherein the light control piece is provided in the vicinity outside the effective display area of the liquid crystal panel.   The liquid crystal display device according to claim 1, wherein a cut portion for fixing the light control piece is provided on an end surface of the light guide plate adjacent to the backlight light source.   The liquid crystal display device according to claim 1, wherein the light control piece is inserted into a cut portion provided on an upper surface of the light guide plate.

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