JP4178968B2 - BACKLIGHT UNIT, ELECTRO-OPTICAL DEVICE, ELECTRONIC DEVICE, METHOD FOR PRODUCING BACKLIGHT UNIT, AND METHOD FOR MANUFACTURING ELECTRO-OPTICAL DEVICE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-dissipating sheet, a backlight unit, and an electro-optical device including the backlight unit, which are used in portable optical televisions, pagers, wall-mounted televisions, notebook computers, electro-optical devices of portable game machines, and the like.
[0002]
[Background]
In recent years, thin and light liquid crystal display devices have been widely used in display units of portable small-sized televisions, pagers, wall-mounted televisions, notebook computers, portable game machines, and all other electronic devices, and the demand for these devices is increasing. There is a tendency.
[0003]
A reflective liquid crystal display device, which is light, thin, and has low power consumption, does not have a light source unit, and performs display visual recognition using only external light. However, in consideration of use in various environments including outdoors and dark places at night, a reflective liquid crystal display device having a front light type backlight unit and a transmission having an edge light type or area light type backlight unit. Type liquid crystal display devices and transflective liquid crystal display devices have also been developed.
[0004]
The backlight unit is, for example, a light guide plate made of a synthetic resin plate such as a transparent acrylic resin for guiding light emitted from a light source to a direction away from the light source, and uniformly irradiating the entire liquid crystal display device with light, The light guide plate includes a light source such as an LED disposed in the vicinity of at least one end face (one side face) along the end face and substantially parallel to the end face.
[0005]
In general, in a liquid crystal display device, a backlight unit that supplies light to the liquid crystal display panel is disposed below the liquid crystal display panel. Therefore, heat from a light source such as an LED constituting the backlight unit is transmitted to the liquid crystal display panel, and a temperature difference occurs between the light source side of the liquid crystal display panel and the opposite side, and the temperature distribution in the surface of the liquid crystal display panel Unevenness occurs. As a result, fluctuations and variations in the threshold voltage (Vth) of the liquid crystal sealed in the liquid crystal display panel occur within the surface of the liquid crystal display panel, the screen becomes whitish near the light source, display unevenness, and display quality deteriorates. There was a problem to do. Note that when the current of the light source is increased in order to increase the screen brightness, the amount of heat generated by the light source increases, and display unevenness due to heat significantly occurs on the screen near the light source.
[0006]
Therefore, a technique has been proposed in which a heat dissipation sheet made of aluminum is provided under the light guide plate near the light source of the backlight unit disposed below the liquid crystal display panel, in contact with the light guide plate (see, for example, Patent Document 1). ).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-318940
[Problems to be solved by the invention]
However, when the heat-dissipating sheet is adhered to the light guide plate, other members constituting the backlight unit, the circuit board, etc., there is a bubble between the sheet and the adhesive surface due to the thinness and softness of the sheet itself. There is a problem that it is easy to enter. If air bubbles or wrinkles are inserted between the heat-dissipating sheet and the heat-dissipating sheet, the thermal conductivity is lowered and the heat-dissipating effect is lowered.
[0009]
The present invention has been made in view of the above points, and an object thereof is to provide a backlight unit and an electro-optical device having a high heat dissipation effect using a heat dissipation sheet.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a backlight unit of the present invention is a backlight unit that is disposed on the back surface of an electro-optic display panel and irradiates the electro-optic display panel. The light source arranged on one end face, the reflector on the back side of the light guide, the heat dissipation sheet, and the circuit board are stacked in this order, and the heat dissipation sheet is attached to the circuit board. A plurality of intermittent slits arranged along one side are provided, and the slits are provided so that a portion where no slit is formed does not coincide between adjacent slits in a direction intersecting with one side. It is characterized by.
[0011]
According to this configuration, by providing an opening (slit) in the heat radiating sheet, in the step of attaching the heat radiating sheet, air that enters between the heat radiating sheet and an object to which the heat radiating sheet is attached is opened in the heat radiating sheet. Since it can escape from the part to the outside, the heat-dissipating sheet can be stuck so as not to generate bubbles and wrinkles. Therefore, the heat generated from the light source is effectively dissipated to prevent the heat from the light source from being transmitted to the electro-optical device used integrally with the backlight unit. Can be improved.
[0012]
In one aspect of the above backlight unit, the opening may have a slit shape. By forming the opening provided in the heat dissipation sheet into a slit shape, the opening can be easily formed. The opening may include a plurality of slit rows formed substantially parallel to each other, and each of the slit rows may include a plurality of slits provided intermittently. By providing a plurality of slits intermittently, it is possible to obtain a high heat radiation effect while ensuring the strength of the entire heat radiation sheet to some extent and maintaining workability. In addition, the width | variety of an opening part can be 0.01 mm or more and 0.1 mm or less, for example, and the thickness of a thermal radiation sheet can be 0.02 mm or more and about 0.1 mm or less. About the width | variety of an opening part, since possibility that a wrinkle will generate | occur | produce will become high when it becomes smaller than 0.01 mm, said range is preferable. In addition, the thickness of the heat dissipation sheet is preferably in the above range since it is insufficient in mechanical strength when it is thinner than 0.02 mm, and a sufficient heat dissipation effect cannot be expected in terms of thermal efficiency. The light source may be an LED.
[0013]
Moreover, according to the backlight unit which concerns on this invention, it is preferable that the light-diffusion sheet is further provided between the light guide and the reflecting plate.
In addition, an electro-optical device can be configured by the backlight unit described above and an electro-optical display panel disposed at a position where light emitted from the backlight unit is emitted. An electronic device provided as a display portion can be configured.
[0014]
In order to achieve the above object, a method for manufacturing a backlight unit according to the present invention is a method for manufacturing a backlight unit for irradiating an electro-optic display panel disposed on the back surface of the electro-optic display panel. A step of affixing the heat dissipation sheet, and a step of arranging the circuit board by facing the heat dissipation sheet to the back surface of the light guide having a light source on one end surface, the heat dissipation sheet being arranged along one side thereof A plurality of intermittent slits are provided, and the slits are provided so that a portion where no slit is formed does not coincide between adjacent slits in a direction intersecting one side.
[0015]
According to the above method for manufacturing a backlight unit, by providing an opening in the heat radiating sheet, in the step of attaching the heat radiating sheet, the air that enters between the heat radiating sheet and the object to which the heat radiating sheet is attached is radiated. Since it can escape from the opening part of a sheet | seat, a heat-radiation sheet can be stuck so that a bubble and a wrinkle may not generate | occur | produce. Therefore, the heat generated from the light source can be effectively radiated.
[0016]
In another aspect of the present invention, a method for manufacturing an electro-optical device includes a step of arranging a light source on an end surface of a light guide plate, a step of forming an opening in a surface of a heat radiating sheet, and the vicinity of the light guide plate. A step of attaching a heat dissipation sheet to at least a portion on the light source side, a backlight unit manufacturing step, a step of manufacturing an electro-optical panel, a step of integrating the electro-optical panel and the backlight unit, Have
[0017]
According to the above electro-optical device manufacturing method, by providing an opening in the heat radiating sheet, in the step of attaching the heat radiating sheet, the air entering between the heat radiating sheet and the object to which the heat radiating sheet is attached is radiated. Since it can escape from the opening part of a sheet | seat, a heat-radiation sheet can be stuck so that a bubble and a wrinkle may not generate | occur | produce. Therefore, the heat generated from the light source is effectively dissipated to prevent the heat from the light source from being transmitted to the electro-optical device used integrally with the backlight unit. Can be improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
[0019]
In this embodiment, a heat dissipation sheet is disposed above a backlight unit having a light source, and heat generated from the light source is efficiently radiated to improve image deterioration due to heat of the liquid crystal display device. In particular, in the present embodiment, in order to prevent air from intervening between the heat dissipation sheet and a substrate to which the heat dissipation sheet is attached, for example, an FPC substrate, the heat dissipation sheet is provided with openings such as cuts and slits. Features.
[0020]
(Structure of the liquid crystal display device)
A liquid crystal display device 100 to which the heat dissipation sheet of the present invention is applied will be described. FIG. 1 is a cross-sectional view of a liquid crystal display device 100 to which a heat dissipation sheet of the present invention is applied. The liquid crystal display device 100 is roughly composed of a liquid crystal display panel 300 and a backlight unit 200.
[0021]
First, the configuration of the liquid crystal display panel 300 will be described.
[0022]
Transparent electrode films 2a and 2b are respectively formed on the surfaces of insulating substrates 1a and 1b such as glass, and an alignment film (not shown) for aligning liquid crystal molecules in a certain direction is further provided. The two insulating substrates 1a and 1b are pasted by a sealing material 3 so that the transparent electrode films 2a and 2b are opposed to each other while maintaining a certain distance by a spacer (not shown). The liquid crystal layer 4 is sandwiched between the two insulating substrates 1a and 1b by filling the liquid crystal material in the gap between the two insulating substrates 1a and 1b. Furthermore, polarizing plates 7a and 7b and phase difference plates 8a and 8b are attached to the outside of the insulating substrates 1a and 1b, respectively, thereby forming the liquid crystal display panel 300.
[0023]
Note that a switching element or the like may be formed on the insulating substrate 1a, and color filters 7a, 7b and 7c, a protective film 8 and the like may be formed on the insulating substrate 1b.
[0024]
When a voltage is applied to the transparent electrode films 2a and 2b, the arrangement of the liquid crystal molecules sandwiched between them changes, and the transmission of light from the backlight unit 200 along with the directions of the absorption axes of the polarizing plates 5a and 5b. The opaqueness is controlled, and a desired display can be obtained.
[0025]
On the other hand, the backlight unit 200 includes an LED 9 as a light source, a light guide 10, a light scattering sheet 11, a reflection plate 12, a heat radiation sheet 13, and a circuit board 14. An LED 9 is attached to one end surface of the light guide 10. In addition, on the surface of the light guide 10, for example, a plurality of light diffusion portions made of large and small concaves and convexes are formed. The light guide 10 is formed of a transparent resin such as polymethyl methacrylate (PMMA) resin or polycarbonate (PC) resin.
[0026]
Incident light from the LED 9 is partially reflected by the reflecting plate 12 and guided by the inside of the light guide 10 while being scattered by the light scattering sheet 11, and the emission surface of the light guide 10 (upper surface in FIG. 1). ) From above. That is, the backlight unit 200 uses the incident light from the LED 9 efficiently and illuminates the liquid crystal display panel 300.
[0027]
The heat dissipation sheet 13 is a sheet of about 0.1 mm made of, for example, aluminum. However, in the present invention, the heat radiation sheet 13 is not limited to an aluminum sheet, and various known materials such as a silicon sheet can be used.
[0028]
In general, the heat dissipation sheet has a role of dissipating heat generated from the LEDs 9 to make it difficult to be transmitted to the liquid crystal display panel 300. From the LED 9, heat of about 60 ° C. is transmitted to the liquid crystal display panel 300, and a temperature difference of about 10 ° C. is generated between the light source side of the liquid crystal display panel 300 and the opposite side thereof. Heat is dissipated to prevent screen display unevenness due to the temperature distribution in the surface of the liquid crystal display panel. That is, the heat dissipation sheet 13 causes fluctuations and variations in Vth of the liquid crystal of the liquid crystal display panel 300 within the surface of the liquid crystal display panel, the screen becomes whitish near the light source, display unevenness, and display quality deteriorates. Etc. are arranged to improve the problem.
[0029]
The heat dissipation sheet 13 is often affixed to a circuit board 14, for example, an FPC (Flexible Printed Circuit) board, mainly manually. For this reason, the conventional heat dissipation sheet is thin and soft, and thus air bubbles and wrinkles often occur.
[0030]
Since the heat dissipation sheet 13 of this embodiment is provided with cuts and slits, generation of bubbles and wrinkles is reduced, and the heat dissipation sheet 13 can be attached in a state of being sufficiently adhered to the attachment portion of the circuit board 14. Therefore, since the heat dissipation sheet 13 is in close contact with the circuit board 14 with a sufficient contact area, the heat from the LED 9 can be efficiently conducted to the heat dissipation sheet 13 and radiated.
[0031]
The heat dissipation sheet 13 according to the present embodiment can provide an excellent display screen not only in the TN type liquid crystal display device but also in the STN type liquid crystal display device.
[0032]
(Heat dissipation sheet)
FIG. 2A shows an example of the heat dissipation sheet according to the present embodiment. In the heat radiation sheet 13a shown in FIG. 2A, a plurality of cuts 20 are intermittently provided in parallel to the short side of the heat radiation sheet 13a. In this example, the basic length of one cut 20 is Y1, and the interval between adjacent cuts 20 is X1. The length Y1 and the interval X1 are determined so that the heat dissipation effect of the entire heat dissipation sheet is optimized according to the characteristics of the heat dissipation sheet to be used, particularly the thinness and softness.
Further, the position of the portion 22 between the intermittently formed cuts 20 does not coincide with the portion 22 in the row of adjacent cuts in the lateral direction, that is, the heat dissipation sheet is shifted in the direction of the row of cuts. The strength of 13a itself can be maintained and the pasting operation can be facilitated.
[0033]
FIG. 2B shows another example of the heat dissipation sheet according to the present embodiment. The heat radiating sheet 13b shown in FIG. 2 (b) intermittently forms slits having a predetermined width X3 instead of the cuts, as compared with the heat radiating sheet 13a shown in FIG. 2 (a). The basic length of the slit is Y2, and the distance between adjacent slits is X2. The slit length Y2, the slit interval X2 and the width x3 of the slit itself are also determined so that the heat radiation effect of the entire heat radiation sheet is maximized in consideration of the material characteristics of the heat radiation sheet 13b.
[0034]
In addition to the method of forming cuts and slits as in the above example of the heat dissipation sheet 13, small holes having a predetermined diameter can be formed on the entire surface of the heat dissipation sheet 13 on average.
[0035]
Thus, by providing a cut, a slit, a small hole or the like in the heat dissipation sheet 13, an air escape path exists between the heat dissipation sheet 13 and the attachment portion of the circuit board 14, and bubbles and wrinkles are less likely to occur. The heat radiation effect by the heat radiation sheet 13 can be improved. In addition, since air can escape, the heat radiation sheet can be attached to the circuit board 14 or the like while releasing air, so that the attachment becomes easy and the efficiency of the attachment work is improved.
[0036]
The slit 20 shown in FIG. 2A is also a kind of slit. In this embodiment, the slit shown in FIG. 2A is called a slit for convenience and the slit shown in FIG. 2B is called a slit. Yes. Therefore, as the scope of the present invention, the term “slit” can be understood as a concept including both the slits shown in FIG. 2A and the slits shown in FIG.
[0037]
Moreover, in this invention, it is preferable that the width | variety of opening parts, such as a cut | interruption shown to Fig.2 (a), a slit shown in FIG.2 (b), or the above-mentioned small hole, shall be 0.01 mm or more and 0.1 mm or less. This is because if the width of the opening is less than 0.01 mm, there is a high possibility that wrinkles will occur in the heat dissipation sheet, while if the width of the opening is too large, the heat dissipation effect of the entire heat dissipation sheet will be reduced. .
[0038]
The thickness of the heat dissipation sheet itself is preferably 0.02 mm or more and 0.1 mm or less. This is because if the thickness of the heat radiating sheet is less than 0.02 mm, the mechanical strength of the heat radiating sheet itself is insufficient, and a sufficient heat radiating effect cannot be expected in terms of thermal efficiency.
[0039]
(Method for manufacturing liquid crystal display device)
Next, a method for manufacturing the liquid crystal display device 100 shown in FIG. 1 will be described with reference to FIGS. 3, 4, and 5. FIG. 3 shows a flowchart of a method for manufacturing the liquid crystal display device 100. FIG. 4 shows a flowchart of a method for manufacturing the liquid crystal display panel 300. FIG. 5 shows a flowchart of the attaching process of the heat radiation sheet 13 according to the present embodiment.
[0040]
First, details of the liquid crystal display panel manufacturing process (process Pa) will be described.
[0041]
First, a substrate 1a is manufactured (process Pa1), a transparent conductive film 2a is formed by sputtering, and patterning is performed by a photolithography method to form a transparent electrode film 2a (process Pa2). Further, an alignment film (not shown) is formed on the transparent electrode film 2a, and a rubbing process or the like is performed (step Pa3).
[0042]
On the other hand, the substrate 1b is manufactured (step Pa4). Further, a transparent conductive film 2b is formed by sputtering on the overcoat layer 8 provided on the color filter red 7a, color filter green 7b, and color filter blue 7c, and patterning is performed by photolithography. A transparent electrode film 2b is formed (step Pa5). If the edge portion of the color filter is not a steep shape or the like, the transparent electrode 2b can be formed even if the overcoat layer 8 is not disposed. Thereafter, an alignment film made of polyimide resin or the like (not shown) is formed on the transparent electrode film 2b, and a rubbing process or the like is performed (step Pa6).
[0043]
And said board | substrate 1a and the board | substrate 1b are bonded together through the sealing material 3 (process Pa7). At this time, the substrate 1a and the substrate 1b are bonded to each other with a substantially prescribed substrate interval by a spacer (not shown) distributed between the substrates.
[0044]
Thereafter, the liquid crystal 4 is sealed from an opening (not shown) of the sealing material 3, and the opening of the sealing material is sealed with a sealing material such as an ultraviolet curable resin (step Pa8). After the main panel structure is completed in this manner, the retardation plates 6a and 6b and the polarizing plates 5a and 5b are attached to the outer surface of the panel structure as needed by a method such as sticking (step Pa9), as shown in FIG. The liquid crystal display panel 300 is completed. The retardation plates 6a and 6b and the polarizing plates 5a and 5b may be attached after the circuit board 14, for example, the FPC board and the liquid crystal display panel 300 are attached.
[0045]
Next, the circuit board manufacturing process (process Pb) will be described.
[0046]
The circuit board manufacturing method uses, for example, a COF method (Chip on Film bonding). Further, an SMT method (surface mount type) may be used. An ACF (Anisotropic Conductive Film) or the like is mounted on the circuit board 14 in the mounting area. ACF is composed of conductive particles coated with an insulating film and an adhesive. A major feature of ACF is that it exhibits conductivity in the vertical direction and exhibits insulation in the horizontal direction by thermocompression bonding.
[0047]
Then, a so-called thermocompression is performed by pressing the driving element such as an IC chip on the ACF mounted on the circuit board 14 against the circuit board 14 while heating, thereby manufacturing a circuit board (FPC board).
[0048]
Next, a connection process (process Pc) between the FPC board and the liquid crystal display panel will be described.
[0049]
In the bonding process of the circuit board 14 and the liquid crystal display panel 300, bonding is performed using, for example, ACF. The wiring terminal portion of the liquid crystal display panel 300 has a thermocompression bonding part for thermocompression bonding the circuit board 14. Therefore, an ACF is mounted between the liquid crystal display panel 300 and the wiring terminals of the circuit board 14 and thermocompression bonding is performed. Thereby, the liquid crystal display panel 300 and the circuit board 14 are electrically joined.
[0050]
Next, the heat radiation sheet sticking step (step Pd) will be described.
[0051]
Referring to FIG. 5, first, the heat radiation sheet 13 of the present embodiment is attached to the back side of the circuit board 14, that is, the liquid crystal display panel 300 side (or the light guide 10 side) (step Pd1). Since the heat radiation sheet 13 of the present embodiment is provided with openings, for example, cuts and slits, bubbles and wrinkles are difficult to enter, and can be easily attached to the circuit board 14 with high adhesion. Generally, the heat radiation sheet 13 is often attached to the circuit board 14 by manual work. In such a case, it is difficult to work on the heat dissipation sheet 13 with a uniform force. However, since the heat radiating sheet 13 is provided with the opening, normally, air easily escapes from the opening even in a state where air bubbles enter. And it can be pasted with high adhesion.
[0052]
Next, it is preferable to perform an autoclave process (process Pd2) on the circuit board 14 to which the heat dissipation sheet 13 is attached. For example, when air bubbles or the like enter between the heat dissipation sheet 13 and the circuit board 14, if the autoclave process is performed, the air bubbles are easily degassed under reduced pressure conditions. Since the heat radiating sheet 13 according to the present embodiment has an opening, it is easier to defoam than a normal heat radiating sheet. That is, the time required for autoclaving is short and efficient.
[0053]
Next, an external appearance inspection (process Pd3) is visually performed on the state of attachment of the heat dissipation sheet 13. At this time, the pasting state of the heat radiation sheet 13 is classified into a non-defective product and a defective product. About the inferior goods with which the adhering state of the thermal radiation sheet 13 is not good, an autoclave process (process Pd2) is implemented again, and bubbles etc. are defoamed. In other words, rework is performed. Then, the appearance inspection (process Pd3) is performed again, and if it is a non-defective product, the next process (Pd4) is performed. Since the heat dissipation sheet 13 according to the present embodiment has an opening, the adhesiveness is high, the necessity for reworking is reduced, the number of processes is reduced, and the cost of the liquid crystal display device is reduced.
[0054]
Next, a panel module set (process Pd4) is performed. Before assembling, static elimination blow is performed on each member to prevent static electricity. By performing the static elimination blow, the occurrence of defects due to static electricity of the liquid crystal display device can be reduced.
[0055]
Since the heat radiating sheet 13 according to the present embodiment has an opening, bubbles and wrinkles are less likely to enter as compared with a conventional heat radiating sheet, and can be attached well. That is, since the heat dissipation sheet 13 is in close contact with the circuit board 14 with a sufficient contact area, the heat from the LED 9 is efficiently conducted to the heat dissipation sheet 13 and the temperature difference of the liquid crystal display panel 300 is reduced. In addition, it is possible to reduce the non-uniformity of contrast due to the temperature difference between the screen display area near the LED 9 and the screen display area far from the light source.
[0056]
Next, the manufacturing process (process Pe) of the light guide unit will be described.
[0057]
The light guide 10 can be manufactured by a device (injection molding machine) for molding a plastic product or the like, for example, a cold runner mold method, and is attached to a circuit board for causing the LED 9 serving as a light source to emit light. Then, the light guide unit is manufactured by attaching the LED 9 to one end face of the light guide 10.
[0058]
Finally, the module assembly process (process Pf) will be described.
[0059]
The liquid crystal display panel 300 to which the circuit board 14 to which the heat dissipating sheet 13 is attached is connected and the light guide unit is attached to the exterior frame. Then, the light scattering sheet 11 and the reflection plate 12 are sequentially attached between the light guide 10 and the circuit board 14 from the liquid crystal display panel 300 side, that is, from above.
[0060]
The liquid crystal display device 100 shown in FIG. 1 can be manufactured by the above manufacturing method. By using the heat dissipation sheet 13 according to the present embodiment, a liquid crystal display device with high display quality without display unevenness can be provided.
[0061]
[Electronics]
FIG. 6 is a schematic configuration diagram of an electronic apparatus using the liquid crystal display device of this embodiment. The electronic apparatus shown here includes the liquid crystal display device 100 and a control unit 110 that controls the liquid crystal display device 100. Here, the liquid crystal display device 100 is conceptually divided into a panel structure 100A and a drive circuit 100B composed of a semiconductor IC or the like. Further, the control unit 110 includes a display information output source 111, a display information processing circuit 112, a power supply circuit 113, and a timing generator 114.
[0062]
The display information output source 111 includes a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), a storage unit such as a magnetic recording disk or an optical recording disk, and a tuning circuit that tunes and outputs a digital image signal. The display information is supplied to the display information processing circuit 112 in the form of an image signal of a predetermined format based on various clock signals generated by the timing generator 114.
[0063]
The display information processing circuit 112 includes various known circuits such as a serial-parallel conversion circuit, an amplification / inversion circuit, a rotation circuit, a gamma correction circuit, and a clamp circuit, executes processing of input display information, and outputs image information thereof. Are supplied to the drive circuit 100B together with the clock signal CLK. The driving circuit 100B includes a scanning line driving circuit, a data line driving circuit, and an inspection circuit. The power supply circuit 113 supplies a predetermined voltage to each component described above.
[0064]
Next, specific examples of electronic devices to which the liquid crystal display device according to the present invention can be applied will be described with reference to FIG.
[0065]
First, an example in which the liquid crystal display device according to the present invention is applied to a display unit of a portable personal computer (so-called notebook personal computer) will be described. FIG. 7A is a perspective view showing the configuration of this personal computer. As shown in the figure, the personal computer 410 includes a main body portion 412 having a keyboard 411 and a display portion 413 to which the liquid crystal display device according to the present invention is applied.
[0066]
Next, an example in which the liquid crystal display device according to the present invention is applied to a display unit of a mobile phone will be described. FIG. 7B is a perspective view showing the configuration of the mobile phone. As shown in the figure, the mobile phone 420 includes a plurality of operation buttons 421, a reception port 422, a transmission port 423, and a display unit 424 to which the liquid crystal display device according to the present invention is applied.
[0067]
Note that, as an electronic device to which the liquid crystal display panel according to the present invention can be applied, in addition to the personal computer shown in FIG. 7A and the mobile phone shown in FIG. Monitor direct-view video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, digital still cameras, etc.
[0068]
[Modification]
The electro-optical device of the present invention is not limited to a passive matrix type liquid crystal display panel, but also an active matrix type liquid crystal display panel (for example, a TFT (thin film transistor) or a TFD (thin film diode)) as a switching element. ) Can be applied in the same manner. In addition to the liquid crystal display panel, the present invention is applied to various electro-optical devices such as an electroluminescence device, an organic electroluminescence device, a plasma display device, an electrophoretic display device, and a field emission display (field emission display device). It is possible to apply similarly.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a liquid crystal display device according to the present invention.
FIG. 2 shows an example of a heat dissipation sheet according to the present invention.
FIG. 3 shows a manufacturing process of a liquid crystal display device to which the present invention is applied.
FIG. 4 shows a manufacturing process of a liquid crystal display panel according to the present invention.
FIG. 5 shows a step of attaching a heat radiation sheet according to the present invention.
FIG. 6 illustrates a structure of an electronic device using a liquid crystal display device to which the present invention is applied.
FIG. 7 illustrates an example of an electronic device including a liquid crystal display device to which the present invention is applied.
[Explanation of symbols]
9 LED, 10 light guide, 11 light scattering sheet 12 reflector, 13 heat dissipation sheet,
14 Circuit board (FPC board)
100 liquid crystal display device, 200 backlight unit,
300 LCD panel,

Claims (5)

A backlight unit disposed on the back of the electro-optic display panel for illuminating the electro-optic display panel,
A light guide;
A light source disposed on one end surface of the light guide;
On the back side of the light guide, the reflector, the heat dissipation sheet, and the circuit board are stacked in this order,
The heat dissipation sheet is affixed to the circuit board,
The heat dissipation sheet is provided with a plurality of intermittent slits arranged along one side thereof,
The said slit is provided so that the part in which the said slit is not formed is provided so that it may not correspond between the said adjacent slits in the direction which cross | intersects the said one side. The backlight unit according to claim 1, wherein a width of the slit is 0.01 mm or more and 0.1 mm or less. The backlight unit according to claim 1 , wherein a thickness of the heat dissipation sheet is about 0.02 mm or more and 0.1 mm or less. The backlight unit according to any one of claims 1 to 3, wherein a light diffusion sheet is further provided between the light guide and the reflection plate. A method for manufacturing a backlight unit for irradiating the electro-optic display panel, disposed on the back surface of the electro-optic display panel,
A process of attaching a heat dissipation sheet to the circuit board;
And placing the circuit board facing the heat dissipation sheet on the back surface of the light guide having a light source on one end surface,
The heat dissipation sheet is provided with a plurality of intermittent slits arranged along one side thereof,
  The method of manufacturing a backlight unit, wherein the slit is provided such that a portion where the slit is not formed is not coincident between adjacent slits in a direction intersecting the one side.

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