JP2004233810A - Surface light source unit, electrooptical device, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface light source unit wherein luminance unevenness caused by fluctuation of temperature is not generated even when a plurality of light emitting elements are used, to provide an electrooptical device using the surface light source unit and to provide an electronic device using the electrooptical device. <P>SOLUTION: In the surface light source unit 3, a plurality of chip-shaped LEDs 333 as the light emitting elements are mounted on an LED mounting substrate 330 of a multilayered wiring structure and the substrate is disposed so that the surface on which the LEDs 333 are mounted faces downward. In a lower shielding plate 2, a plate spring part 21 formed by folding an end part upward elastically abuts against a lower end part of each LED 333. Thereby, heat generated at each LED 333 is directly and efficiently escaped to the lower shielding plate 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface light source unit that emits light toward an electro-optical panel such as a liquid crystal panel, an electro-optical device using the surface light source unit as a backlight device, and an electronic apparatus using the electro-optical device. is there.
[0002]
[Prior art]
In an electro-optical device using a transmissive or transflective electro-optical panel in which an electro-optical material such as liquid crystal is sandwiched between a pair of substrates, a surface light source unit as a backlight device is provided on the back side of the electro-optical panel. A predetermined image is displayed using the light emitted from the surface light source unit. Here, in the surface light source unit, at least a shield member, a reflection member, and a light guide plate are arranged in this order, and a light emitting unit that emits light to an end of the light guide plate is arranged near an end of the light guide plate. Have been.
[0003]
In such a surface light source unit, a cold cathode tube is conventionally used as a light emitting unit. However, when the electro-optical device is used as a display unit of a mobile phone, a mobile computer, or the like, such a portable electronic device is driven by a battery, so that the surface light source unit is required to have low power consumption. For this reason, in recent years, a bullet-shaped LED (light emitting diode) has been used as a light emitting unit (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-8-160892 (page 3 and FIG. 1)
[0005]
[Problems to be solved by the invention]
However, when a plurality of LEDs are used for the light emitting unit, if the temperature of each of the plurality of LEDs fluctuates due to heat at the time of lighting, the amount of light emitted from each LED also fluctuates. There is a problem that occurs.
[0006]
In addition, the electro-optical device is required to be downsized, and the space for disposing the LEDs is required to be reduced. However, such a reduction in the space decreases the heat radiation efficiency. This may cause uneven brightness.
[0007]
In view of the above problems, an object of the present invention is to provide a surface light source unit that does not generate uneven brightness due to temperature variation even when a plurality of light emitting elements are used, an electro-optical device using the surface light source unit, and An object of the present invention is to provide an electronic apparatus using the electro-optical device.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the present invention, at least a shield member, a reflection member, and a light guide plate are arranged in this order, and near the end of the light guide plate, light is emitted to the end of the light guide plate. In a surface light source unit in which a plurality of light emitting elements are arranged, a heat radiating member having at least a metal portion is in direct contact with each of the plurality of light emitting elements or via a bonding material. .
[0009]
In the present invention, since the heat radiating member is in contact with each of the plurality of light emitting elements, heat generated in each of the light emitting elements escapes to the heat radiating member. Therefore, even when a plurality of light emitting elements are used in the light emitting section, the temperature does not vary among the light emitting elements. Therefore, since the amount of light emitted from each light emitting element does not vary, uneven brightness does not occur in the light emitted from the surface light source unit.
[0010]
In the present invention, when a bonding material is used, it is preferable to use a double-sided tape containing a metal layer as the bonding material. When the heat radiating member and the light emitting element are brought into contact with each other using the double-sided tape as a bonding material, when the double-sided tape includes a metal layer, the heat of the light emitting element smoothly escapes to the heat radiating member via the double-sided tape.
[0011]
In the present invention, each of the plurality of light-emitting elements has an emission optical axis oriented in a direction parallel to a mounting surface of a light-emitting element mounting board on which the light-emitting elements are mounted, and the light-emitting element mounting board includes the light-emitting element. There is a case where the surface on which the light emitting element is mounted faces downward so that the element faces the side end face of the light guide plate and is arranged along the side end face. In such a case, it is preferable that the heat radiating member be configured to contact the lower end of each of the plurality of light emitting elements. When the emission optical axis of the light emitting element is parallel to the mounting surface of the light emitting element mounting board, the light emitting element mounting board is arranged with the side on which the light emitting element is mounted facing downward or downward, but the light emitting element is mounted. If the light emitting element mounting board is arranged with the side facing downward, and the heat radiating member is in contact with the lower end of each of the plurality of light emitting elements, heat of the light emitting element is transferred to the shielding member via the heat radiating member. Can be escaped to
[0012]
In the present invention, a chip-type LED can be used as the plurality of light emitting elements. When a chip-type LED is used, a plurality of LEDs can be arranged in a narrow space as compared with a case where a conventional bullet-type LED is used. Therefore, the size and thickness of the electro-optical device can be reduced. In addition, when a chip-type LED is used, a sufficient space can be secured between the LEDs even when a plurality of LEDs are arranged in a narrow space, so that heat radiation efficiency is high. Therefore, even when the temperature of the LED rises, temperature variation between the LEDs hardly occurs. Therefore, there is no variation in the amount of emitted light between the LEDs, so that there is no uneven brightness in the light emitted from the surface light source unit.
[0013]
In the present invention, the reflection member is integrally disposed from a position below the light guide plate to a position below the plurality of light emitting elements, and the reflection member is located below the plurality of light emitting elements as the heat dissipation member. It is preferable that a portion to be brought into contact with each of the plurality of light emitting elements. With this configuration, it is possible to prevent luminance unevenness due to temperature variation without adding a new member.
[0014]
In the present invention, as the reflection member, a member having a metal layer having a transparent insulating layer laminated on the upper surface can be used.
[0015]
In the present invention, the heat dissipation member is formed separately from the shield member and the reflection member, and is configured to be sandwiched between lower end portions of each of the plurality of light emitting elements and the shield member. You may.
[0016]
In the present invention, it is preferable that the shield member urges the heat radiating member disposed between the shield member and the light emitting element toward the light emitting element. With such a configuration, the heat radiation member and the light emitting element are in close contact with each other without joining the heat radiation member to the light emitting element using a bonding material, so that the efficiency of heat transfer from the light emitting element to the heat radiation member is improved.
[0017]
In the present invention, it is preferable that the shield member elastically abuts on a lower surface of the heat radiating member disposed between the shield member and the light emitting element. With this configuration, since the shield member and the heat radiating member are in close contact with each other, the heat of the light emitting element can be efficiently released to the shield member via the heat radiating member.
[0018]
In the present invention, the shield member may have a structure in which the shield member itself elastically contacts the lower end of each of the light emitting elements as the heat radiating member. With this configuration, it is possible to prevent luminance unevenness due to temperature variation without adding a new member.
[0019]
In an electro-optical device using a surface light source unit to which the present invention is applied as a backlight device, an electro-optical panel is arranged on the light emitting surface side of the light guide plate with respect to the surface light source unit.
[0020]
The electro-optical device according to the present invention is used for electronic devices such as a mobile phone, a PDA, a personal digital assistant (PDA), and a mobile computer.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
[0022]
[Embodiment 1]
(Overall configuration of electro-optical device)
FIG. 1 is an exploded perspective view showing the overall configuration of an electro-optical device with a backlight to which the present invention is applied. FIGS. 2A, 2B, and 2C are cross-sectional views each showing a configuration of a main part of the electro-optical device with a backlight shown in FIG. 1, and a reflection sheet used for a surface light source unit of the electro-optical device. FIG. 2 is a cross-sectional view and a cross-sectional view of a double-sided tape used as a bonding material for fixing a reflection sheet.
[0023]
1 and 2A, the electro-optical device 1 of this embodiment is mounted as a display unit on a battery-driven electronic device such as a mobile phone, a PDA, a personal digital assistant, and a mobile computer.
[0024]
The electro-optical device 1 includes a surface light source unit 3 (backlight device) including a metal lower shield plate 2 (shield member) also serving as a lower case, a frame-shaped spacer 8, a lower polarizing plate 4, and an electro-optical panel 5. , An upper polarizing plate 6 and a metal upper shield plate 7 which also serves as an upper case are stacked in this order, and each component has a substantially rectangular planar shape. In storing these components between the lower shield plate 2 and the upper shield plate 7, in the present embodiment, a rectangular frame-shaped resin holder 9 (frame-shaped holder) is used. The light source unit 3, the spacer 8, the lower polarizing plate 4, and the electro-optical panel 5 are arranged. Here, the spacer 8 secures a predetermined gap between the surface light source unit 3 and the lower polarizing plate 4.
[0025]
A display window 71 having a size corresponding to an image display area of the electro-optical panel 5 described below is formed on the upper shield plate 7. While covering the area, the electro-optical panel 5 is physically protected.
[0026]
In this embodiment, as the electro-optical panel 5, a TFT active matrix type transmission type liquid crystal panel is used. As a liquid crystal panel of this type, a well-known liquid crystal panel can be used, and thus detailed description is omitted. A TFT array substrate 51 in which pixels including pixel electrodes and pixel switching elements are formed in a matrix is provided. Similarly, a counter substrate 52 in which a counter electrode, a color filter, and the like are formed on the surface of a substrate such as quartz glass or heat-resistant glass, a sealing material for bonding these substrates, and an area defined by the sealing material between the substrates. It is roughly composed of a liquid crystal as an electro-optical material which is enclosed and held.
[0027]
The opposing substrate 52 is smaller than the TFT array substrate 51, and the peripheral portion of the TFT array substrate 51 is in a state of protruding from the outer peripheral edge of the opposing substrate 52. Therefore, on the TFT array substrate 51, around the image display area, a scanning line driving circuit, a data line driving circuit, and the like are formed by using a driving circuit TFT (not shown) formed simultaneously with the pixel switching TFT. Can be formed. In addition, if input / output terminals are formed in a region of the TFT array substrate 51 protruding from the end of the opposite substrate 52, as shown in FIG. 1, a drive IC 54 is mounted on these input / output terminals by COF mounting. Flexible substrate 53 can be mounted. In this embodiment, the flexible substrate 53 is further connected to a flexible substrate 56 on which various electronic components 55 constituting a power supply circuit and the like of the surface light source unit 3 are mounted. The elongated portion 56 of 56 is connected to the LED mounting board 330 of the surface light source unit 3.
[0028]
In the electro-optical device 1 configured as described above, the normally white mode / normal black is provided on the side of the TFT array substrate 51 (light incident side) and the side of the opposing substrate 52 (light exit side) of the electro-optical panel 5. The lower polarizing plate 4 and the upper polarizing plate 6 made of a plastic sheet are arranged in a predetermined direction according to the mode.
[0029]
In the present embodiment, the light from the surface light source unit 3 for the backlight device enters from the TFT array substrate 51 and exits from the counter substrate 524. The light may be incident from the substrate 524 and emitted from the TFT array substrate 51. The electro-optical panel 5 may be a TFD active matrix type transmissive liquid crystal panel, a passive matrix type transmissive liquid crystal panel, or the like, in addition to a TFT active matrix type transmissive liquid crystal panel. In addition, a transflective liquid crystal panel may be used instead of the transmissive liquid crystal panel.
[0030]
(Configuration of surface light source unit 3)
FIGS. 3A, 3B, 3C, and 3D show the configuration of the light emitting unit of the surface light source unit 3 used as a backlight device in the electro-optical device 1 shown in FIGS. 1 and 2A. The bottom view shown, the equivalent circuit diagram of the light emitting portion, the sectional view of the light emitting portion shown in FIG. 3A taken along line AA ', and the light emitting portion shown in FIG. It is sectional drawing at the time of cutting by a line.
[0031]
As shown in FIGS. 1, 2A, and 3, in the electro-optical device 1 of the present embodiment, the surface light source unit 3 used as the backlight device has a rectangular shape made of a resin molded product having translucency. A light emitting unit 33 including a light guide plate 31, an LED mounting board 330 formed of a rigid substrate having a multilayer wiring structure such as a glass-epoxy substrate, or a flexible substrate having a multilayer wiring structure; and a light emitting unit 33 for driving the light emitting unit 33. And a power supply circuit 39. In the surface light source unit 3, a lower shield plate 2, a reflection sheet 35, and a lower shield plate 2 are arranged in this order on the lower surface side of the light guide plate 31, while a lens is provided on the upper surface side of the light guide plate 31. A sheet-like optical component 37 such as a sheet or a diffusion sheet is arranged.
[0032]
In the light emitting section 33, an elongated board is used as the LED mounting board 330, and a plurality of chip-shaped LEDs 333 as light emitting elements are mounted in a row on the lower surface of the LED mounting board 330. Therefore, the space for disposing the LEDs 333 may be smaller than that in the case of using bullet-shaped LEDs.
[0033]
Here, each of the LEDs 333 has its emission optical axis directed in a direction parallel to the mounting surface of the LED mounting board 330. For this reason, the LED mounting board 330 is disposed with the surface on which the LEDs 333 are mounted facing downward, and the LEDs 333 are arranged so as to face the side end surfaces 311 of the light guide plate 31 and along the side end surfaces 311.
[0034]
In the present embodiment, for example, the plurality of LEDs 333 are divided into two groups 331 and 332 as shown in FIGS. 3A and 3B, and in each of the two groups 331 and 332. , For example, five LEDs 333 are connected in series. The two groups 331 and 332 are electrically connected in parallel. That is, the anode wiring 338 and the ground wiring 339 are common wirings between the two groups 331 and 332, and the power supply circuit 39 is connected thereto. Further, a zener diode 38 is connected in parallel to the light emitting unit 33 as a protection circuit.
[0035]
In the present embodiment, the plurality of LEDs 333 are arranged such that the LEDs 333 belonging to different groups 331 and 332 are adjacent to each other. Therefore, the first wiring pattern 336 for the LED 333 belonging to the first group 331 and the second wiring pattern 337 for the LED 333 belonging to the second group 332 cross on the LED mounting board 330. Therefore, in this embodiment, as shown in FIGS. 3C and 3D, a substrate having a multilayer wiring structure in which wiring patterns 336 and 337 are formed between different layers is used as the LED mounting substrate 330.
[0036]
Referring again to FIG. 2A, in the surface light source unit 3 of the present embodiment, when the plurality of LEDs 333 are arranged close to the side of the light guide plate 31 between the upper shield plate 7 and the lower shield plate 2, The reflection sheet 35, the light guide plate 31, and the sheet-shaped optical component 37 are arranged on the inner side. Also, an overhanging portion 95 for fixing the substrate is provided inside the resin holder 9, the upper surface of the LED mounting substrate 330 is bonded and fixed to the lower surface of the overhanging portion 95, and the LED mounting substrate 330 is turned downward with the plurality of LEDs 333 facing downward. It is attached to the resin holder 9. Therefore, even if the emission optical axis of the chip-shaped LED 333 is in a direction parallel to the mounting surface of the LED mounting substrate 330, the LED 333 is disposed by directing the LED mounting substrate 330 on the side on which the LED 333 is mounted. Can be arranged so as to face the side end surface 311 of the light guide plate 31 and along the side end surface 311.
[0037]
As shown in FIGS. 2A and 3A, the LED mounting board 330 is disposed such that an edge of the LED 333 located on the emission optical axis side overlaps one edge of the light guide plate 31. The LED mounting board 330 is also supported by the light guide plate 31. Here, the portion where one edge of the LED mounting board 330 is overlapped on the light guide plate 31 is an empty space created by stacking the sheet-shaped optical component 37 on the light guide plate 31 and the LED The mounting substrate 330 is equal to or thinner than the total thickness of the sheet-shaped optical component 37. Therefore, even if such a structure is adopted, it does not prevent the electro-optical device 1 from being reduced in size and thickness.
[0038]
(Heat radiation structure for LED333)
In the surface light source unit 3 configured as described above, the reflection sheet 35 is integrally arranged from a position below the light guide plate 31 to a position below the LEDs 333. For this reason, on the upper surface of the lower shield plate 2, the reflection sheet 35, the LED 333, and the LED mounting board 330 are arranged in this order, and the reflection sheet 35 directly contacts the lower end of the LED 333 as a heat dissipation member, The lower surface is in direct contact with the lower shield plate 2.
[0039]
Here, as shown in FIG. 2B, the reflection sheet 35 has a structure in which transparent plastic sheets 352 and 353 are laminated on each of the upper and lower surfaces of a metal layer 351 such as silver or a silver alloy. The metal layer 351 functions as a substantial heat dissipation member.
[0040]
(motion)
In the electro-optical device 1 configured as described above, when the LED 333 is turned on by the surface light source unit 3, the light emitted from the LED 333 enters the light guide plate 31 and is reflected by the light guide plate 31 or the reflection sheet 35. The light is emitted toward the light emitting surface 315 (the side of the sheet-shaped optical component 37), which is the upper surface of the light guide plate 31, while repeating. Then, the light incident on the sheet-shaped optical component 37 is emitted to the electro-optical panel 5 after being subjected to an action such as imparting light scattering by the sheet-shaped optical component 37. On the other hand, in the electro-optical panel 5, the alignment state of the liquid crystal is controlled for each pixel by the image signal applied to the pixel electrode. For example, when the electro-optical panel 5 is configured in the TN mode, the liquid crystal is twisted and aligned at an angle of 90 ° between the substrates, and such a twisted alignment is released by applying an electric field to the liquid crystal between the substrates. . Therefore, the alignment state of the liquid crystal can be controlled for each pixel depending on whether or not an electric field is externally applied between the substrates.
[0041]
Therefore, in the electro-optical panel 5, the light emitted from the surface light source unit 3 is adjusted to a predetermined linearly polarized light by the lower polarizing plate 4 on the incident side, then enters the liquid crystal layer, and passes through a certain region. The linearly polarized light is emitted with the transmitted polarization axis twisted, while the linearly polarized light that has passed through other regions is emitted without the transmitted polarization axis being twisted. Therefore, if the lower polarizing plate 4 on the incident side and the upper polarizing plate 6 on the emitting side are arranged so that their transmission polarization axes are orthogonal to each other (normally white), they are arranged on the emitting side of the electro-optical panel 5. Only the linearly polarized light whose transmission polarization axis is twisted by the liquid crystal passes through the upper polarizing plate 6. On the other hand, if the upper polarizing plate 6 on the emission side is arranged so that the lower polarizing plate 4 on the incidence side and the transmission polarization axis are parallel (normally black), then the upper polarizing plate 6 is arranged on the emission side of the electro-optical panel 5. Only the linearly polarized light whose transmitted polarization axis has not been twisted by the liquid crystal passes through the upper polarizing plate 6. Therefore, arbitrary information can be displayed by controlling the alignment state of the liquid crystal for each pixel.
[0042]
(Main effects of this embodiment)
As described above, in the present embodiment, since the emission optical axis of the chip-shaped LED 333 is in a direction parallel to the mounting surface of the LED mounting board 330, the LED mounting board 330 faces down on the side where the LED 333 is mounted. It is arranged facing. Therefore, the LEDs 333 face the side end surface 311 of the light guide plate 31 and are arranged along the side end surface 311. Here, only the reflection sheet 35 and the like are disposed on the side opposite to the light exit surface 315 with respect to the light guide plate 31, but various sheet-like optical components are disposed on the side of the light exit plate 315 with respect to the light guide plate 31. Since the spacer 37, the spacer 8, the lower polarizing plate 4, the electro-optical panel 5, and the like are arranged, there is a spatial margin. In the present embodiment, the LED mounting board 330 is arranged with the side on which the LED 333 is mounted facing downward, so that the LED mounting board 330 reduces the size and thickness of the electro-optical device 1. There is no hindrance. In particular, in this embodiment, since the LED mounting board 330 is equal to or thinner than the total thickness of the sheet-shaped optical component 37, the thickness of the LED mounting board 330 can be absorbed by the thickness of the sheet-shaped optical component 37. Therefore, the LED mounting board 330 does not prevent the electro-optical device 1 from being reduced in size and thickness.
[0043]
Further, since the LED mounting board 330 is arranged with the side on which the LEDs 333 are mounted facing downward, the reflection sheet 35 can be brought into contact with each of the plurality of LEDs 333 as a heat dissipation member. Therefore, the heat generated in each of the LEDs 333 escapes to the lower shield plate 2 via the reflection sheet 35, so that even when a plurality of LEDs 333 are used, the temperature does not vary among the LEDs 333. Therefore, since the amount of light emitted from each of the plurality of LEDs 333 does not vary, the light emitted from the surface light source unit 3 does not have uneven brightness.
[0044]
Moreover, since the reflection sheet 35 is used as a heat radiation member, there is an advantage that it is not necessary to add a new member.
[0045]
Further, in this embodiment, a number of LEDs 333 that can be driven by a voltage that can be generated by the power supply circuit 39 of the surface light source unit 3 are connected in series, and two groups 331 and 332 composed of a plurality of LEDs 333 connected in series in this way are configured. Power is supplied from the common power supply circuit 39 to each of the groups 331 and 332. For this reason, since the same drive current flows through at least the plurality of LEDs 333 belonging to the same group, the amount of light emitted from the LEDs 333 is constant. Therefore, the light emitted from the light guide plate 31 does not have a luminance variation.
[0046]
Further, a lower driving voltage is required as compared with the case where all of the plurality of LEDs 333 are connected in series. Therefore, when the electro-optical device 1 according to the present embodiment is mounted on battery-driven electronic devices such as a mobile phone, a PDA, a personal digital assistant, and a mobile computer, the power supply circuit of these electronic devices requires a high drive voltage. There is no need for a booster circuit for generation. In addition, in the surface light source unit 3 of the present embodiment, since the amount of light to be incident on the light guide plate 31 can be ensured only by increasing the number of the groups of the LEDs 333, an image of appropriate brightness can be displayed on the display unit of the electronic device. .
[0047]
Further, in the light emitting unit 33 of the surface light source unit 3, even when any one of the LEDs 333 is broken and becomes disconnected, the LEDs 333 belonging to the same group as the LEDs 333 are turned off, but the LEDs 333 belonging to the other groups are turned off. It is in the lighting state. Therefore, the display of the image on the electro-optical device 1 can be continued.
[0048]
Moreover, the plurality of LEDs 333 are arranged such that LEDs belonging to different groups are adjacent to each other. Therefore, even when the amount of light emitted from the LEDs 333 varies between groups, luminance unevenness does not occur. In addition, even if the LEDs 333 belonging to one group are turned off, the LEDs 333 belonging to the other group are turned on, so that the light amount is reduced, but light is emitted from the entire surface of the surface light source unit 3. Therefore, in the electro-optical device 1, an image can be displayed on the entire surface of the image display area.
[0049]
[Improvement Example 1 of Embodiment 1]
In the surface light source unit 3 shown in FIG. 2A, as for the reflection sheet 35, as shown in FIG. 2C, adhesive layers 112 and 113 are provided on the upper surface and the lower surface of a metal film 111 such as aluminum. The thus formed double-sided tape 11 may be joined to the lower end of the LED 333. With this configuration, the reflection sheet 35 is in close contact with the LED 333 via the double-sided tape 11. Further, since the double-sided tape 11 itself also includes the metal film 111, the heat transfer property is good. Therefore, the heat generated in each of the LEDs 333 efficiently escapes to the lower shield plate 2 via the reflection sheet 35.
[0050]
Note that the reflection sheet 35 and the lower shield plate 2 may also be joined by the double-sided tape 11 shown in FIG. With this configuration, heat can efficiently escape from the reflection sheet 35 to the lower shield plate 2.
[0051]
[Embodiment 2]
FIG. 4 is a cross-sectional view illustrating a configuration of a light emitting unit of the surface light source unit used in the electro-optical device according to Embodiment 2 of the present invention.
[0052]
In the second embodiment, the reflection sheet 35 is brought into close contact with the LED 333 or the lower shield plate 2 made of metal by the double-sided tape 11 shown in FIG. 2C. However, as shown in FIG. 2 may be bent upward to form the leaf spring portion 21, and the leaf spring portion 21 may press the reflecting member 35 against each lower end of the LED 333. Other configurations are substantially the same as those of the first embodiment, and thus common portions are denoted by the same reference numerals and are not illustrated, and description thereof is omitted.
[0053]
According to this embodiment, the reflection sheet 35 and the LED 333 and the reflection sheet 35 and the lower shield plate 2 can be directly adhered to each other without using the double-sided tape 11, so that the LED 333 is generated. The heat efficiently escapes to the lower shield plate 2 via the reflection sheet 35. Further, there is an advantage that the temperature variation of the LED 333 can be prevented without adding a new member.
[0054]
When the reflection sheet 35 and the LED 333 are joined by the double-sided tape 11, the plate spring portion 21 formed on the lower shield plate 2 abuts on the reflection member 35 with elasticity. It is possible to efficiently escape to the shield plate 2 through the intermediary.
[0055]
Further, when the reflection sheet 35 and the lower shield plate 2 are joined with the double-sided tape 11, the plate spring portion 21 formed on the lower shield plate 2 urges the reflection member 35 toward the LED 333, so that the LED 333 is generated. Heat can be efficiently released to the shield plate 2 via the reflection member 35.
[0056]
[Embodiment 3]
FIG. 5 is a cross-sectional view illustrating a configuration of a light emitting unit of the surface light source unit used in the electro-optical device according to Embodiment 3 of the present invention.
[0057]
In the first embodiment, the reflection sheet 35 is used as a heat radiating member. However, in this embodiment, as shown in FIG. 5, the lower shield plate 2 made of metal is in contact with the lower end of the LED 333 as a heat radiating member. Here, the lower shield plate 2 and the LED 333 may be joined with the double-sided tape 11 described with reference to FIG. 2C, but in the present embodiment, the end of the lower shield plate 2 is bent upward. The leaf spring portion 21 is configured to elastically directly contact the lower ends of the LEDs 333 with elasticity.
[0058]
For this reason, according to this embodiment, the heat generated in each of the LEDs 333 escapes directly and efficiently to the lower shield plate 2. Further, the temperature variation of the LED 333 can be prevented without adding a new member.
[0059]
Other configurations are substantially the same as those of the first embodiment, and thus common portions are denoted by the same reference numerals and are not illustrated, and description thereof is omitted.
[0060]
[Embodiment 4]
FIG. 6 is a cross-sectional view illustrating a configuration of a light emitting unit of a surface light source unit used in an electro-optical device according to Embodiment 4 of the present invention.
[0061]
In the first to third embodiments, the reflection sheet 35 or the lower shield plate 2 is used as a heat radiating member. However, in the present embodiment, as shown in FIG. A heat dissipating member 12 made of a metal sheet separate from these members is arranged, and this heat dissipating member 12 is in contact with the lower end of the LED 333. Here, the heat dissipating member 12 and the LED 333, and the heat dissipating member 12 and the lower shield plate 2 may be joined with the double-sided tape 11 described with reference to FIG. An end of the shield plate 2 is bent upward to form a plate spring portion 21, and the plate spring portion 21 elastically contacts the heat radiating member 12 to each lower end of the LED 333.
[0062]
For this reason, according to the present embodiment, since the heat radiation member 12 and the LED 333 and the heat radiation member 12 and the lower shield plate 2 are directly in close contact with each other, the heat generated in each of the LEDs 333 passes through the lower shield member via the heat radiation member 12. Escape to board 2 efficiently.
[0063]
When the heat dissipating member 12 and the LED 333 are joined with the double-sided tape 11, the plate spring portion 21 formed on the lower shield plate 2 abuts on the heat dissipating member 12 with elasticity. It is possible to efficiently escape to the shield plate 2 through the intermediary.
[0064]
Further, when the heat radiating member 12 and the lower shield plate 2 are joined with the double-sided tape 11, the plate spring portion 21 formed on the lower shield plate 2 urges the heat radiating member 12 toward the LED 333. Heat can be efficiently released to the shield plate 2 via the heat radiation member 12.
[0065]
Other configurations are substantially the same as those of the first embodiment, and thus common portions are denoted by the same reference numerals and are not illustrated, and description thereof is omitted.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view illustrating an overall configuration of an electro-optical device with a backlight according to a first embodiment of the present invention.
FIGS. 2A, 2B, and 2C are cross-sectional views each showing a configuration of a main part of the electro-optical device with a backlight shown in FIG. 1, and a reflection used for a surface light source unit of the electro-optical device; FIG. 2 is a cross-sectional view of a sheet and a cross-sectional view of a double-sided tape used as a bonding material for fixing a reflection sheet.
FIGS. 3A, 3B, 3C, and 3D are plan views showing a configuration of a light emitting unit of a surface light source unit used as a backlight device in the electro-optical device shown in FIGS. 1 and 2; , An equivalent circuit diagram of the light-emitting portion, a cross-sectional view of the light-emitting portion shown in FIG. 3A taken along line AA ', and a light-emitting portion shown in FIG. 3A taken along line BB'. It is sectional drawing at the time of doing.
FIG. 4 is a cross-sectional view illustrating a configuration of a main part of an electro-optical device with a backlight according to a second embodiment of the present invention.
FIG. 5 is a cross-sectional view illustrating a configuration of a main part of an electro-optical device with a backlight according to a third embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating a configuration of a main part of an electro-optical device with a backlight according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 electro-optical device 2 lower shield plate (shield member)
3 surface light source unit (backlight device)
4 Lower polarizing plate 5 Electro-optical panel 6 Upper polarizing plate 7 Upper shield plate 8 Spacer 9 Resin holder 11 Double-sided tape (joining material)
12 heat dissipating member 21 leaf spring portion 31 of lower shield plate light guide plate 33 light emitting portion 35 reflection sheet (reflection member)
37 Sheet-shaped optical component 38 Zener diode (protection circuit)
39 power supply circuit 51 TFT array substrate 52 opposing substrate 330 LED mounting substrate (light emitting element mounting substrate)
311 Side end surface 315 of light guide plate Light emitting surface 331, 332 of light guide plate LED group 333 Chip type LED (light emitting element)

Claims (12)

A surface light source in which at least a shield member, a reflection member, and a light guide plate are arranged in this order, and a plurality of light emitting elements that emit light to the end of the light guide plate are arranged near an end of the light guide plate. In the unit
A surface light source unit, wherein a heat radiating member having a metal portion is in direct contact with each of the plurality of light emitting elements or via a bonding material. 2. The surface light source unit according to claim 1, wherein the bonding material is a double-sided tape including a metal layer. 3. The light-emitting element according to claim 1 or 2, wherein the plurality of light-emitting elements have an emission optical axis oriented in a direction parallel to a mounting surface of a light-emitting element mounting board on which the light-emitting elements are mounted.
The light emitting element mounting board faces the side on which the light emitting element is mounted downward so that the light emitting element faces the side end surface of the light guide plate and is arranged along the side end surface. Placed
The surface light source unit, wherein the heat radiating member is in contact with a lower end of each of the plurality of light emitting elements. The surface light source unit according to claim 3, wherein the plurality of light emitting elements are chip-type LEDs. The reflective member according to claim 3, wherein the reflecting member is integrally arranged from a position below the light guide plate to a position below the plurality of light emitting elements,
A surface light source unit, wherein the reflection member has a portion located below the plurality of light-emitting elements as the heat dissipation member, in contact with each of the plurality of light-emitting elements. 6. The surface light source unit according to claim 5, wherein the reflection member includes a metal layer having a transparent insulating layer laminated on an upper surface. 5. The heat radiation member according to claim 3, wherein the heat radiation member is formed separately from the shield member and the reflection member, and is sandwiched between lower end portions of each of the plurality of light emitting elements and the shield member. A surface light source unit characterized by the above-mentioned. The surface according to any one of claims 5 to 7, wherein the shield member urges the heat radiating member disposed between the shield member and the light emitting element toward the light emitting element. Light source unit. The surface light source unit according to any one of claims 5 to 7, wherein the shield member elastically abuts a lower surface of the heat dissipation member disposed between the shield member and the light emitting element. 5. The surface light source unit according to claim 3, wherein the shield member elastically contacts the lower end of each of the light emitting elements as the heat radiating member. With respect to the surface light source unit defined in any one of claims 1 to 10, an electro-optical panel is arranged so as to overlap the light exit surface side of the light guide plate,
The electro-optical device, wherein the surface light source unit is used as a backlight device for the electro-optical panel. An electronic apparatus using the electro-optical device defined in claim 11.

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