JP2008170728A - Backlight device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease manufacturing cost while maintaining the accuracy of a finished chassis of a backlight device. <P>SOLUTION: The backlight device 3 is irradiated with a light from the back of a transmissive display panel 5 held by a middle chassis 6 and has a side frame 15 and a back plate 16, wherein the side frame 15 and the back plate 16 constituting the chassis are configured as different components and a fitting section is formed in each joint portion between the middle chassis 6 and the side frame 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a backlight device and a display device, and more particularly to a backlight device and a display device suitable for application to a liquid crystal display device or the like.

  In recent years, a liquid crystal display device has been developed to have a large display screen, a lighter weight, a thinner thickness, lower power consumption, and the like as compared with a cathode ray tube (CRT). Plasma display panels) are used for television receivers and various displays.

  A liquid crystal display device encapsulates liquid crystal between two transparent substrates of various sizes, and changes the light transmittance by changing the direction of liquid crystal molecules by applying a voltage to optically display a predetermined image or the like. To do. Since the liquid crystal display device is not a light emitter, the liquid crystal display device is provided with a backlight device that functions as a light source, for example, on the back surface of the liquid crystal panel. The backlight device includes, for example, a primary light source, a light guide plate, a reflective film, a lens sheet, or a diffusion film, and supplies display light over the entire surface of the liquid crystal panel. Conventionally, a cold cathode fluorescent lamp (CCFL) in which mercury or xenon is sealed in a fluorescent tube is used as the backlight device. Cold cathode fluorescent lamps have problems such as low emission luminance, short lifetime, or low luminance region on the cathode side and poor uniformity.

  Recently, instead of a cold cathode fluorescent lamp, two light-emitting diodes of three primary colors red, green and blue (hereinafter referred to as “LED (Light Emitting Diode)”) are provided on the back side of the diffusion film. An LED type backlight device that obtains white light by arranging in a dimension is drawing attention. Such an LED backlight device has low power consumption and can display a high luminance even on a large liquid crystal panel.

  Patent Documents 1 and 2 describe examples of backlight devices.

JP 2005-284106 A (paragraph [0023]) JP 2005-283866 A (paragraph [0026])

  By the way, as described in Patent Document 1 and Patent Document 2, the backlight chassis is generally formed as a single unit by bending a sheet metal. However, in the recent television receiver market, the screen size tends to increase, and it has become difficult to integrally mold the housing. Further, for example, in the case of the above-described LED type backlight device, the light source chamber (light guide space), in particular, the dimension in the depth direction needs to be sufficiently large in order to uniformize the light supplied to the liquid crystal panel due to the characteristics of the LED. There is. That is, the mold for integrally molding becomes large, it becomes difficult to achieve the processing accuracy, and the mold cost is also increased. Therefore, it is necessary to reduce the manufacturing cost while ensuring the accuracy of the completed housing.

  On the other hand, when it comes to a large liquid crystal display device, it is important to use a design to make it look small. For example, in the liquid crystal display device 100 of the conventional example shown in FIG. 9, the upper side frame 101 and the side side frame 102 are first fixed to the corner portion of the backlight chassis by screws 104. The back chassis 103 is fixed to the back surfaces of the upper side frame 101 and the side frame 102. In such a case, since the corner portion is formed at a right angle, the casing of the large liquid crystal display device feels large as it is.

  The present invention has been made in view of such points, and an object of the present invention is to reduce the manufacturing cost while ensuring the accuracy of the completed casing of the backlight device.

  In order to solve the above problems, a backlight device according to the present invention is a backlight device including a housing that irradiates light from the back surface of a transmissive display panel held by a middle chassis and includes a side frame and a back plate. The side frame and the back plate constituting the housing are configured as separate parts, and a fitting portion is formed at each joint portion of the middle chassis and the side frame.

  According to the said structure, it can join accurately by providing a fitting part in fixation of a side frame and a middle chassis. By providing such a fitting portion, the stress is dispersed and the overall rigidity is improved.

  Further, the display device of the present invention is a display device having a backlight device configured by irradiating light from the back surface of the transmissive display panel held by the middle chassis and including a casing including a side frame and a back plate. The side frame and the back plate constituting the housing are configured as separate parts, and a fitting portion is formed at each joint portion of the middle chassis and the side frame.

  According to the said structure, it can join accurately by providing a fitting part in fixation of a side frame and a middle chassis. By providing such a fitting portion, the stress is dispersed and the overall rigidity is improved. Furthermore, each component can be connected closely, and dust prevention and light leakage can be reduced.

  According to the present invention, it is possible to reduce the manufacturing cost while ensuring the accuracy of the completed casing of the backlight device. Further, since dustproof and light leakage can be reduced, the quality of the display device is maintained and the image quality is improved.

  Hereinafter, examples of embodiments of the present invention will be described with reference to the accompanying drawings. In each embodiment described below, the display device of the present invention is applied to a transmissive liquid crystal display device including a backlight device.

First, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an exploded perspective view of an example of a liquid crystal display device to which the display device of the present invention is applied. As shown in FIG. 1, a liquid crystal display device 1, which is an example of a display device, includes a liquid crystal panel unit 2 and a backlight unit (backlight device) that emits display light in combination with the back side of the liquid crystal panel unit 2. 3 is provided.

  The liquid crystal panel unit 2 includes a frame-shaped front frame 4, a liquid crystal panel 5, and a frame-shaped middle chassis 6 that functions as a support means for the optical sheet. The middle chassis 15 has a shape in which the backlight unit 3 is narrowed from the front surface to the back surface. In the liquid crystal panel unit 2, the outer peripheral edge of the liquid crystal panel 5 is placed in a groove formed in the lower side of the middle chassis 6. In this state, the liquid crystal panel 5 is sandwiched and held between the front frame 4 and the middle chassis 6 via a spacer, a guide member, or the like (not shown).

  The liquid crystal panel 5 omits details, but generally encloses a liquid crystal between a first glass substrate and a second glass substrate that are kept at a distance from each other by spacer beads and applies a voltage to the liquid crystal. The light transmittance is changed by changing the direction of the liquid crystal molecules. In the liquid crystal panel 5, a striped transparent electrode, an insulating film, and an alignment film are formed on the inner surface of the first glass substrate. Further, a color filter of three primary colors, an overcoat layer, a striped transparent electrode, and an alignment film are formed on the inner surface of the second glass substrate. In addition, the deflection film and the retardation film are bonded to the surfaces of the first glass substrate and the second glass substrate.

  Furthermore, the liquid crystal panel 5 has an alignment film made of polyimide arranged in a horizontal direction with liquid crystal molecules at the interface, and the deflection film and the retardation film achromatic and whitened the wavelength characteristics to achieve full color using a color filter. Received images are displayed in color. The liquid crystal panel 5 is not limited to such a structure, and may be a liquid crystal panel having various configurations conventionally provided.

  The backlight unit 3 is disposed on the back side of the liquid crystal panel unit 2 described above and is composed of a plurality of light source substrates 14 for supplying display light, and the light emitting unit is installed and generated in the light emitting unit. A base member (heat radiating unit) that radiates the heat generated, and a back panel (rear housing) 16 that holds the base member and is combined with the middle chassis 6 and the side frame 15 to form a supporting means for the housing. Is provided. The backlight unit 3 has an outer dimension that is opposed to the entire rear surface of the liquid crystal panel unit 2 and is combined in a state in which the opposing space portion (light source chamber) is optically sealed.

  The light source board 14 is a horizontally long rectangular wiring board, and an appropriate number of red LEDs, green LEDs, blue LEDs (hereinafter collectively referred to as LEDs) and the like are arranged and mounted in a predetermined order. A light emitting block is constituted by three primary color LEDs, and the basic unit of the light emitting block is formed of, for example, one red LED, two or one green LED, and one blue LED. In the example shown in FIG. 1, the wiring board has three rows for the sake of space, but the present invention is not limited to this example.

  A substantially box-shaped reflection sheet 12 having a bottom surface portion 13 is installed on the front surface of the light source substrate 14. In the bottom surface portion 13 of the reflection sheet 12, LED insertion holes 13a are formed at positions corresponding to the respective LEDs mounted on the surface of the light source substrate 14, and each color corresponding to each of the LED insertion holes 13a is formed. LED penetrates. Thereby, each LED is installed so as to be confined in a space (light guide space) formed by the diffusion plate 11 and the reflection sheet 12. Of the light emitted from each LED to the surroundings, the light emitted toward the bottom surface portion 13 of the reflection sheet 12 is reflected on the surface and emitted toward the liquid crystal panel 5. As will be described later, the bottom surface 13 of the reflection sheet 12 is provided with holes other than the LED insertion holes 13a.

  The reflection sheet 12 is formed with side wall portions 12 a that are inclined at predetermined angles on four sides of the bottom surface portion 13. For example, an angle at which the illumination surface luminance distribution is the best is selected between 0 and 90 ° as the predetermined angle. The reflection sheet 12 is molded using, for example, a foamable PET (Polyethylene Terephthalate) material containing a fluorescent agent. The foamable PET material has a high reflectivity characteristic of about 95%, and has a characteristic that a scratch on the reflecting surface is not noticeable with a color tone different from the metallic luster color. The reflective sheet 12 may be formed of, for example, silver having a mirror surface, aluminum, or stainless steel.

  On the front surface of the reflection sheet 12, an optical sheet group 10 including a diffusion plate 11 that diffuses light emitted from each LED and optical sheets 7, 8, and 9 is installed. The diffusing plate 11 is disposed on the surface opposite to the surface facing the liquid crystal panel 5 of the optical sheet group 10 so that the lower ends thereof are aligned and laminated. The diffuser plate 11 is made of a slightly thick plate body formed of a transparent synthetic resin material having a light guiding property, such as an acrylic resin or a polycarbonate resin.

  The optical sheet group 10 is, for example, a functional sheet that decomposes display light supplied from an LED mounted on the light source substrate 14 and incident on the liquid crystal panel 5 into polarization components orthogonal to the incident light, and compensates for the phase difference of the light wave. A plurality of optical sheets having various optical functions such as a functional sheet for widening the viewing angle and preventing coloring or a functional sheet for diffusing display light are laminated. For example, the optical sheet 9 shown in FIG. 1 is a diffusion sheet, the optical sheet 8 is a prism sheet, and the optical sheet 7 is a polarization conversion sheet, and the irradiation surface has the same shape and size. Note that the configuration of the optical sheet group 10 is not limited to the above-described optical sheet, and includes, for example, a luminance enhancement film for improving luminance, two upper and lower diffusion sheets sandwiching a retardation film and a prism sheet, and the like. Also good.

  In the backlight unit 3 configured as described above, the display light supplied from the LEDs mounted on the plurality of light source substrates 14 is incident on the diffusion plate 11 from the back side. The diffusing plate 11 guides the display light incident from the one main surface side while diffusing and reflecting the display light inside, and makes the light incident on the optical sheet group 10 from the other main surface side. Further, when a part of the display light emitted from each LED is incident on the diffusion plate 11 beyond the critical angle, it is reflected on the surface of the diffusion plate 11. The reflected light from the surface of the diffusion plate 11 and a part of the display light radiated from each LED to the surroundings and reflected by the reflection sheet 12 are repeatedly reflected between the diffusion plate 11 and the reflection sheet 12. The reflectance is improved by the principle of increased reflection.

  Finally, the backlight unit 3 is combined with the liquid crystal panel 5, and the four sides are further covered with the front frame 4, so that the whole including the liquid crystal panel 5 is fixed and the liquid crystal display device 1 is completed. As described above, the liquid crystal display device 1 is assembled by stacking the component parts in close contact with each other. The front frame 4, the middle chassis 6, the side frame 15, and the back panel 16 are formed of metal, resin, or the like.

  FIG. 2 is a schematic perspective view of the liquid crystal display device 1 shown in FIG. The liquid crystal display device 1 has four sides on the front side covered with the front frame 4 and four sides on the back side covered with the side frame 15.

  3 is a main part of a cross-sectional view taken along line AA of the liquid crystal display device 1 shown in FIG. In FIG. 3, the front frame 4 and the middle chassis are fixed by being screwed into the screw holes 27 with the protective sheet 21 sandwiched therebetween. Further, a male screw is screwed into the screw hole 28, and the back panel 16 is fixed to the side frame mounting portion 33a. A liquid crystal panel is installed in the groove 22 formed in the middle frame 6. In addition, the optical sheet group 10 and the diffusion plate 11 are sandwiched in the groove 23 formed by the middle chassis 6 and the side frame 15. On the back side of the diffusion plate 11, a light source chamber 24 sealed with the diffusion plate 11 and the reflection sheet 12 is formed. The side frame 15 of the present embodiment is composed of three frame portions 31, 32, and 33 as shown in FIG. Of the three frames 31, 32, and 33 that constitute the lower surface of the side frame 15, the intermediate frame portion 32 is not perpendicular to the protective sheet 21, but is inclined in the direction of narrowing the light source chamber 24.

  FIG. 4 is a main part of a cross-sectional view taken along line BB of the liquid crystal display device 1 shown in FIG. In FIG. 4, a fitting portion is provided at each joint portion of the side frame 15 and the middle chassis 6. A gap can be eliminated by each fitting part. The bottom end portion of the groove 23 formed by the side frame 15 and the middle chassis 6 is fitted with a side end 24b of the side frame 15 in a groove 24a provided on the middle chassis 6 side. Further, in the vicinity of the screw hole 29 for fixing the side frame 5 and the front frame 4, the notch 25 b at the end of the side frame 25 b is engaged with the notch 25 a formed along the end of the middle chassis 6. Match. Further, in the vicinity of the screw hole 28 for fixing the side frame 15 to the back panel 16, an end portion 26b of the back panel 16 is formed in a groove portion 26a formed along the end portion of the back panel mounting portion 33a of the side frame 15. It is mated.

  Next, a method for installing the middle chassis 6 on the side frame 15 will be described. FIG. 5 is a perspective view (1) showing a mating portion of the middle chassis. FIG. 6 is a perspective view (1) showing a mating portion of the middle chassis.

  In FIG. 5, the end portion of the lower surface portion 6 </ b> C of the middle chassis 6 is fitted into the notch 41 formed at the end portion of the lower surface portion 6 </ b> C of the middle chassis 6, and is fixed with screws 104. FIG. 6 shows a state in which the lower surface portion 6C of the middle chassis 6 is removed. When installing the middle chassis 6 requiring accuracy on the side frame 15, first, the backlight unit 3 is installed with the long side as a reference, and the short side is set with that as a reference. 6 will be described as an example. First, after the lower surface portion 6C of the middle chassis 6 is attached, the side surface portion 6B is fixed.

  Further, a cushioning material is introduced into each gap 42 at the four corners where it is difficult to achieve processing accuracy (for example, within ± 0.2 mm). In other words, make a gap and adjust by inserting a thick cushioning material. As an example of the buffer material, urethane foam such as Polon (manufactured by Roger Sinoac Co., Ltd.) excellent in vibration proofing and shock absorption can be mentioned. Accordingly, in the middle chassis 6 of the present embodiment, as shown in the rear view in FIG. 7, each joint portion of the upper surface portion 15A, the left side surface portion 15B, the lower surface portion 15C, and the right side surface portion 15D is processed at 45 degrees. .

  In the present embodiment, as shown in FIG. 8, the side frame shape is processed so that the backlight housing is squeezed from the front to the back.

  According to the above-described embodiment, the side frame 15 and the middle chassis 6 can be fixed to each other by providing the fitting portion with high accuracy. By providing such a fitting portion, the stress is dispersed and the overall rigidity can be obtained. Moreover, each part can be closely connected by a fitting part, and dust prevention and light leakage can be reduced. By reducing the size of the parts, the mold becomes smaller, leading to cost reduction and easy handling. Furthermore, the shape of the side frame 15 can be processed so that the backlight housing is squeezed from the front to the back, so that the volume of the backlight housing can be reduced and the volume of the set can also be reduced. This side frame shape allows all screws to be hit from the front surface of the backlight unit when assembling the housing, facilitating manufacturing and reducing dust generation.

  The above-described embodiment is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the above description. Unless stated to the effect, the present invention is not limited to these forms. For example, the materials used and the numerical conditions such as the amount, processing time, and dimensions mentioned in the above description are only suitable examples, and the dimensions and shapes and arrangement relationships in the drawings used for the description are also schematic.

  In addition to the liquid crystal display device using the transmissive liquid crystal panel shown in the above embodiment, the present invention can be applied to other display devices such as an LED display device that does not use the transmissive display panel.

  Furthermore, it goes without saying that various modifications and changes can be made without departing from the spirit of the present invention, such as using a CCFL or a light bulb instead of the LED as the light source of the display device.

It is a disassembled perspective view which shows an example of the liquid crystal display device to which the display apparatus of this invention was applied. It is a perspective view of the liquid crystal display device of FIG. It is the sectional view on the AA line of FIG. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is explanatory drawing (1) of the middle chassis matching part which concerns on one Embodiment of this invention. It is explanatory drawing (2) of the middle chassis matching part which concerns on one Embodiment of this invention. It is a middle chassis rear view concerning one embodiment of the present invention. It is explanatory drawing of the corner part of the middle chassis back surface which concerns on one Embodiment of this invention. It is explanatory drawing of the conventional liquid crystal display device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Liquid crystal panel unit, 3 ... Backlight unit, 4 ... Front frame, 5 ... Liquid crystal panel, 6 ... Middle chassis, 7, 8, 9 ... Optical sheet, 10 ... Optical sheet group, 10a ... Lower end, 11 ... Diffuser, 12 ... Reflective sheet, 12a ... Inclined part, 13 ... Bottom part, 13a ... Hole, 14 ... Light source board, 15 ... Side frame, 15A, 15B, 5C ... Middle chassis frame, 16 ... Back panel , 31, 32, 33 ... middle chassis, 42 ... gap

Claims (4)

In a backlight device including a housing including a side frame and a back plate, which irradiates light from the back surface of the transmissive display panel held by the middle chassis.
The side frame and the back plate constituting the housing are configured as separate parts,
A backlight device, wherein a fitting portion is formed at each joint portion between the middle chassis and the side frame. When the four sides of the middle chassis are separated and the middle chassis is installed on the side frame, the middle chassis bottom surface portion is first fixed to the side frame, and then the middle chassis side surface portion is secured with reference to the middle chassis bottom surface portion. The backlight device according to claim 1. The both end portions of each side of the middle chassis are formed at 45 degrees with respect to the longitudinal direction, and a buffer material is inserted into the joint portion of the end portion of each side of the middle chassis. Item 2. The backlight device according to Item 1. In a display device having a backlight device configured by irradiating light from the back surface of a transmissive display panel held by a middle chassis and including a casing including a side frame and a back plate,
The side frame and the back plate constituting the housing are configured as separate parts,
A display device, wherein a fitting portion is formed at each joint portion between the middle chassis and the side frame.

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