JP2010250122A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device with superior optical characteristics, by suppressing brightness variation for each product by preventing position displacement of a light source in a liquid crystal display device including a backlight used in a mobile telephone etc. <P>SOLUTION: An LED 5 is held pressing to a light conductive plate 11 and is fixed to a side face of the light conductive plate 11 by providing a moving section having elasticity, in a resin frame 6. Consequently, the liquid crystal display device which is superior in the optical characteristics is attained, by minimizing the light from a light source minimum, leaking from a gap between the LED 5 and the light conductive plate 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device, and relates to a technique of a liquid crystal display device using a backlight in which a light source is disposed on a side surface of a light guide plate.

  Liquid crystal display devices used for cellular phones and the like are required to be small and have high luminance. Along with this, there is a growing demand for higher brightness and smaller outer shape for backlights that illuminate liquid crystal panels from the back. A conventional liquid crystal display device includes a product including an FPC (flexible wiring board) in which an LED is mounted in a backlight. In such a configuration, the positioning of the LED and the light guide plate can be visually performed, and the backlight can be visually confirmed by turning on the LED. However, it is necessary to secure a region for electrical connection in the FPC, which is a cause of increasing the shape of the liquid crystal display device. Therefore, in order to reduce the outer shape of the liquid crystal display device, a method of mounting electronic components and LEDs on an FPC mounted on a liquid crystal panel is used.

  FIG. 6 shows the liquid crystal panel 2 and the backlight 14 constituting such a conventional liquid crystal display device. As shown in the figure, the liquid crystal panel 2 includes an upper glass substrate 16 and a lower glass substrate 17 in which liquid crystal is sealed, and an upper polarizing plate 15 and a lower polarizing plate 18 respectively attached to the outer surfaces of the display areas of these substrates. ing. Further, the driving IC 3 and the FPC 4 are mounted on the terminal portion of the lower glass substrate 17, and the LED 5 and the electronic component 19 are mounted on the FPC 4. The LED 5 is disposed on the short side surface of the light guide plate 11 and serves as a light source for the backlight 14. The liquid crystal panel 2 is illuminated from the back by the backlight 14.

  The backlight 14 includes a light guide plate 11 that emits light from a light source from a side surface and exits from an upper surface, a diffusion sheet 10, a lower prism sheet 9, and an upper prism sheet 8 provided on the upper surface of the light guide plate 11. The reflection sheet 12 provided on the lower surface of the light guide plate 11 is housed in the resin frame 6. The backlight 14 and the liquid crystal panel 2 are fixed by the double-sided tape 7. Although not shown, after the liquid crystal panel 2 is mounted on the resin frame 6, the FPC 4 is bent 180 degrees toward the back side and stored in the resin frame 6. The LED 5 is disposed between the cut resin frame 6 and the light guide plate 11.

  As described above, in the configuration in which the electronic component and the LED are mounted on the FPC of the liquid crystal panel, since the LED and the light guide plate cannot be visually positioned, the distance between the LED and the light guide plate varies, and the optical characteristics of the backlight. Was getting worse. In addition, since it is impossible to perform a lighting inspection with a single backlight before product assembly, defects are confirmed after product assembly, resulting in an increase in the cost of waste. In order to improve this, there is a method of adjusting the distance between the LED and the light guide plate according to each product after the product is assembled by using an assembly jig (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2008-003128 (page 8, FIG. 9)

  However, when the assembly jig is used, it is easy to determine the positions of the LED and the light guide plate, but the work efficiency is deteriorated because adjustment is performed for each product using the jig. In particular, when a plurality of LEDs are used, the outer dimensions and optical characteristics vary among the individual LEDs, which further reduces the working efficiency. In order to prevent the cause of this variation, it is necessary to improve the accuracy of each component, reduce the assembly clearance between the resin frame and the light guide plate, and improve the assembly accuracy. However, if such measures are taken, the overall manufacturing cost increases, such as an increase in component costs and a decrease in work efficiency of the assembly process.

  In addition, in order to improve the optical characteristics of the backlight, the loss of light incident on the light guide plate is prevented by making the position of the LED mounted on the FPC and the light guide plate as close as possible, and the light from the LED is made efficient. It is necessary to enter the light guide plate well.

  In order to solve such a problem, the display device of the present invention has a frame that accommodates an FPC on which a light source is mounted, a display element on which the FPC is mounted, and a light guide plate disposed on the back surface of the display element. The movable part which has elasticity was provided. With such a configuration, the light source can be fixed in a state in which the light source is pressed by the movable portion and is in close contact with the side surface of the light guide plate.

  According to the present invention, since it is possible to fix the light guide plate and the LED in contact with each other, it is possible to minimize the loss of light emitted from the LED and efficiently enter the light guide plate. . Therefore, it is possible to prevent a decrease in the optical characteristics of the backlight due to the positional accuracy of the LED and the light guide plate.

  In addition, since the movable part absorbs mounting variations of individual LEDs, the optical characteristics can be improved efficiently even if a plurality of LEDs are used in the product.

  Further, in the present invention, the distance between the LED and the light guide plate can be controlled after the liquid crystal display panel and the backlight are assembled. As a result, the work efficiency can be improved and the product can be easily restored when a defect occurs. In addition, a liquid crystal display device excellent in optical characteristics without product variation can be provided.

It is a front view of the liquid crystal display device which concerns on the Example of this invention. It is sectional drawing of AA of FIG. It is a schematic diagram which shows a part of backlight which concerns on the Example of this invention. It is a schematic diagram of the LED mounting part which shows 1st embodiment of this invention. It is a schematic diagram of the LED mounting part which shows 2nd embodiment of this invention. It is sectional drawing which shows the structure of the conventional liquid crystal display device.

  In the display device of the present invention, an FPC mounted with a light source is connected to a display element, and the display element and a light guide plate that illuminates the display element from the back are housed in a frame. Further, a movable part having elasticity is formed on the frame. With such a configuration, when the light source is attached to the frame, the light source is pressed by the movable portion and fixed in a state of being in close contact with the side surface of the light guide plate. A movable part can be comprised by providing a slit in a flame | frame.

  For example, a slit having an opening may be formed in the frame, and a movable part may be provided at both ends of the opening so as to press the two end portions of the light source. A movable portion may be provided at a portion corresponding to the central portion of the light source so as to press one place of the light source.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  The configuration of the liquid crystal display device 1 of the present embodiment is schematically shown in FIG. As shown in the figure, the liquid crystal panel 2 includes an upper glass substrate 16 and a lower glass substrate 17 in which liquid crystal is encapsulated, and an upper polarizing plate 15 and a lower polarizing plate 18 respectively attached to the outer surfaces of these substrates. An IC 3 for driving the liquid crystal panel 2 is mounted on the lower glass substrate 17. FIG. 2 shows a cross section taken along line A-A in FIG. The liquid crystal panel 2 is electrically connected to an electronic component for driving the IC 3 and an FPC (flexible wiring board) 4 on which a light emitting diode LED 5 serving as a light source of the backlight 14 is mounted. These serve as a liquid crystal driving portion and are combined with the backlight 14 to complete the liquid crystal display device 1.

  The liquid crystal panel 2 on which the FPC 4 is mounted is fixed to the resin frame 6 which is a constituent member of the backlight 14 by the double-sided tape 7. The double-sided tape 7 is made of a light-shielding material and has a role of preventing light leakage. After the liquid crystal panel 2 is mounted on the resin frame 6, the FPC 4 is bent 180 degrees toward the back side and stored in the resin frame 6. The LED 5 is housed in a recess provided in the resin frame 6 and faces a light incident portion of the light guide plate 11 that changes the light incident from the LED 5 to surface light emission.

  The light guide plate 11 is fixed by a claw-shaped hook installed on the resin frame 6. On the light guide plate 11, a diffusion sheet 10 that reduces luminance unevenness, a lower prism sheet 9 that directs light to the liquid crystal panel 2, and an upper prism sheet 8 are installed. These sheets are provided on the resin frame 6. After the position is determined by the unevenness, the double-sided tape 7 is used for fixing. The upper and lower prism sheets are arranged so that the prism angles are orthogonal to each other, and direct light from the light guide plate 11 toward the liquid crystal panel 2 in both the horizontal and vertical directions. The reflection sheet 12 is disposed on the back surface of the light guide plate 11 and reflects the light emitted to the back surface of the light guide plate 11 toward the liquid crystal panel 2 to increase the light use efficiency.

  The LED 5 is disposed on the side surface on the short side of the light guide plate 11. In this embodiment, after the backlight 14 and the liquid crystal panel 2 are assembled in the resin frame 6, the LED 5 is inserted between the resin frame 6 and the light guide plate 11, and the LED 5 is moved by the movable portion provided in the slit of the resin frame 6. Is pressed so as to be in close contact with the side surface on the short side of the light guide plate 11 to fix the position of the LED 5. By such a method, it is possible to reduce the loss of light incident from the LED 5, increase the luminance of the backlight, and realize a liquid crystal display device having excellent optical characteristics. A method for fixing the LED 5 between the resin frame 6 and the light guide plate 11 will be specifically described below.

  FIG. 3 is a top view showing the arrangement of the resin frame, the LED, and the light guide plate of the liquid crystal display device of this embodiment. A slit 13 is formed in the resin frame 6 by cutting a part of the resin. A movable portion having a spring function is formed on the light guide plate 11 side by the slit 13. The cutting dimension D is the same as the LED outer dimension F, and the dimension E between the movable part and the light guide plate 11 is set to be smaller than that. With such a configuration, when the movable portion is moved, the slit 13 is narrowed and the LED 5 can be mounted. Furthermore, since the elasticity of the movable part is restored when the LED 5 is mounted, the LED 5 is pressed by the movable part and fixed in a state of being in contact with the side surface of the light guide plate 11.

  FIG. 4 shows an enlarged detail of the shape of the LED mounting portion B shown in FIG. FIG. 4A shows the state before the LED 5 is mounted, and FIG. In this embodiment, the outer dimension F of the LED 5 is set to 1.2 mm, and similarly the cutting dimension D of the resin frame 6 is set to 1.2 mm.

  The resin frame 6 in FIG. 4 a is provided with a slit 13 for forming a movable part on the mounting part of the LED 5. A movable part is a tongue part provided in the both ends of the opening part of the slit 13, has an elastic function, and presses two edge parts of LED. The movable part is formed by a part of the resin frame 6. Although the shape of the slit 13 depends on molding conditions, in this embodiment, the width of the movable portion is about 0.3 mm, and the movable range of the movable portion is about 0.4 mm. A protrusion G for facilitating the mounting of the LED 5 is installed at the tip of the movable part. In this embodiment, the shape of the protrusion G is a semicircular shape of about 0.1 mm. Thereby, the dimension E of the upper part of the slit 13 before mounting becomes narrow by the protrusion G.

  FIG. 5b shows the completion of the mounting of the LED5. The LED 5 is mounted between the light guide plate 11 and the resin frame 6 by narrowing the space between the slits 13 using the elasticity of the movable part. When the LED 5 is mounted, the protrusion G of the movable part comes into contact with the two ends of the LED 5, and the elasticity of the movable part is restored, so that the LED 5 is pressed against the light guide plate 11. Fixed in close contact.

  Generally, the light guide plate 11 has a variation of about 0.05 mm to 0.1 mm in the outer dimension due to the assembly clearance and the molding variation. Therefore, the light guide plate 11 slightly moves within the resin frame 6. Therefore, even if the outer dimension of the LED 5 becomes 1.2 mm or more due to individual variations of the LED, the outer dimension of the LED 5 can be obtained by utilizing the movable area of the movable part formed by the slit 13 and the free area of the light guide plate. Can be absorbed. Even when the outer dimension of the LED 5 is 1.2 mm or less, the LED 5 presses against the light guide plate 11 because the dimension of the semicircular projection G provided at the tip of the movable portion compensates for the decrease in the outer dimension of the LED 5. And fixed. With such a configuration, in the present invention, it is possible to fix the LED 5 to the side surface of the light guide plate 11 by absorbing variations in the outer dimensions of the individual LEDs 5 and mounting variations generated in the FPC 4.

  In the present embodiment, the shape of the LED 5 to be mounted and the shape of the slit 13 constituting the movable portion are different from those in the first embodiment. Moreover, LED5 is pressed by a movable part over the whole surface centering on a center part.

  FIG. 5 is an enlarged view of the shape of the mounting portion of the LED 5 of the present embodiment, showing details. FIG. 5a is a diagram showing the state before the LED 5 is mounted. In the second embodiment, the slit 13 includes a hole provided in the resin frame 6. An arch-shaped movable portion is formed by the resin frame 6 on the light guide plate 11 side of the hole portion of the slit 13. The arch-shaped movable part has a predetermined thickness and has elasticity. Further, in order to facilitate the mounting of the LED 5, the movable portion is provided with a taper angle so that the central portion of the arch shape is raised.

  FIG. 5b shows the completion of the mounting of the LED5. The LED 5 is mounted between the light guide plate 11 and the resin frame 6 by narrowing the gap between the slits 13 by using the elasticity of the arch-shaped movable part. When the LED 5 is mounted, the elasticity of the movable portion is restored, so that the LED 5 is pressed against the light guide plate 11, and the LED 5 and the light guide plate 11 are closely attached and fixed. At this time, since the thickness of the central part of the movable part is thicker than the end part, the central part of the LED 5 is pressed more strongly. Moreover, since the movable part has an arch shape, the contact point between the LED 5 and the resin frame 6 can be secured in a wider area, and an effect of forcing the inclination of the LED 5 can be obtained.

1 Liquid crystal display device 2 Liquid crystal panel 3 IC
4 Flexible wiring board 5 LED
6 Resin frame 7 Double-sided tape 8 Upper prism sheet 9 Lower prism sheet 10 Diffusion sheet 11 Light guide plate 12 Reflective sheet 13 Slit 14 Backlight 15 Upper polarizing plate 16 Upper glass substrate 17 Lower glass substrate 18 Lower polarizing plate 19 Electronic component

Claims (9)

An FPC with a light source mounted;
A display element to which the FPC is connected;
A light guide plate that is disposed on the back surface of the display element and that emits light from the light source from the side surface and exits from the top surface;
A frame that houses the light guide plate and the display element;
A movable part having elasticity is formed on the frame,
The display device, wherein the light source is pressed by the movable portion and fixed to a side surface of the light guide plate.   The display device according to claim 1, wherein the light source is pressed by the movable portion so as to be in close contact with a side surface of the light guide plate.   The display device according to claim 1, wherein the movable part is configured by a slit formed in the frame.   The display device according to claim 3, wherein the movable unit presses two end portions of the light source.   The display device according to claim 4, wherein the slit is formed to have an opening on the light source side, and the movable part is a tongue provided at both ends of the opening.   The display device according to claim 5, wherein a semicircular protrusion is formed on the tongue of the movable portion.   The display device according to claim 3, wherein the movable portion presses a central portion of the light source.   The display device according to claim 7, wherein the slit is formed by making a hole in the frame, and the movable portion has a taper angle and a raised arch shape at a central portion.   The display device according to claim 1, wherein the movable portion has a width of 0.3 mm and a movable range of 0.4 mm.

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