JP3858879B2 - Light unit - Google Patents

Description

  The present invention relates to a light unit in which a light emitting element is built in a thermoplastic resin member by pressing laminated thermoplastic resin members in a heated state.

For example, as a backlight unit used in a liquid crystal display assembly, one using a cold cathode tube 2 mounted on a power supply substrate 1 as shown in FIG. 5 is provided, and light emitted from the cold cathode tube 2 is provided. The light is introduced into the prism sheet 3 so that the light is reflected evenly by the diffusion plate 4.
JP 2002-9349 A

However, the cold cathode tube 2 has a short life and requires the power supply substrate 1, which is an obstacle to reducing the thickness of the backlight unit. Moreover, since the cold cathode tube 2 contains mercury, which is a substance that is a heavy load to the environment, there is a concern about the environment.
Then, although the structure which arrange | positions an LED chip on a board | substrate like Unexamined-Japanese-Patent No. 2002-9349, and diffuses the light from an LED chip with a diffusing plate can be considered, the board | substrate with which the LED chip was mounted, and a diffusing plate Since it is a separate body, it is troublesome to assemble and further reduction in thickness is desired.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light unit that can be easily assembled and can be further reduced in thickness.

  According to the invention of claim 1, the light emitting element is positioned so as to be electrically connected to the conductive material filled in the via hole of the wiring film substrate, and the light emitting element mounting surface side of the wiring film substrate is used for light diffusion. The film substrates are laminated so as to be positioned, and they are pressed in a heated state. Thereby, the thermoplastic resin members are welded to each other, and the light emitting element is built in the thermoplastic resin member. In this case, since the light diffusing means can be integrated, the thickness can be reduced. Moreover, since it can manufacture with a press, manufacture is easy.

According to invention of Claim 2, the light from a light emitting element can be scattered effectively.
According to the third and fourth aspects of the invention, since the LED chip is used, the thickness can be further reduced.
According to the invention of claim 5, the light emitted backward from the light emitting element can be directed forward without waste.

Hereinafter, an embodiment in which the present invention is applied to a liquid crystal display assembly will be described with reference to FIGS.
FIG. 2 is a cross-sectional view schematically showing the structure of the backlight unit used in the liquid crystal display assembly. In FIG. 2, the backlight unit 11 is manufactured by bonding a light source substrate 12 and an aluminum plate (corresponding to a reflecting member) 13. Hereinafter, the light source substrate 12 will be described.

  The light source substrate 12 used in the present embodiment is a multilayer substrate previously developed by the applicant, and can be recycled at a higher quality and lower cost than the conventional multilayer substrate. The film substrate is based on a resin film made of a crystalline transition type thermoplastic resin that can be multilayered. As shown in FIG. 3, this crystalline transition type thermoplastic resin is amorphous at a low temperature, melts as the temperature rises, and further crystallizes when the temperature rises above a predetermined crystallization temperature. It is a special resin that has the property that in a crystallized state, the elastic modulus hardly changes regardless of the temperature drop.

FIG. 4 schematically shows a method for manufacturing a multilayer substrate.
(1) First step: Etching the conductor foil (a copper foil having a thickness of 18 microns, hereinafter referred to as a conductor pattern, which may be an aluminum foil or the like) 15 attached to one side of the resin film 14 as an insulating substrate Pattern with. The resin film 14 is a resin film having a thickness of 25 to 75 microns made of 35 to 65% by weight of polyetheretherketone resin and 35 to 65% by weight of polyetherimide.

  (2) Second step: When the conductor patterning is completed, the protective film 16 is attached to the surface where the conductor is not formed. After the protective film 16 is pasted, a carbon dioxide laser is irradiated from the resin film 14 side to form a low via hole 17 having the conductor pattern 15 as a bottom surface. The formation of the via hole 17 prevents the opening of the conductor pattern 15 by adjusting the output of the carbon dioxide laser and the irradiation time. An excimer laser or the like can be used for forming the via hole 17 in addition to the carbon dioxide laser. In addition, although mechanical processing such as drilling is possible, a laser is desirable for making a fine hole.

  (3) Third step: When the formation of the via hole 17 is completed, the via hole 17 is filled with a conductive paste (corresponding to a conductive material) 18 as an interlayer connection material. The conductive paste 18 is obtained by adding a binder resin or an organic solvent to metal particles such as copper, silver, and tin and kneading them into a paste. The conductive paste 18 is printed and filled into the via hole 17 with a screen printing machine using a metal mask with the conductor pattern 15 side of the single-sided conductor film facing down.

(4) Fourth step: After filling the conductive paste 18, the protective film 16 is peeled off. The wiring film substrate 19 can be manufactured as described above.
(5) Fifth step: The wiring film substrate 19 manufactured as described above is turned over so that the conductor pattern 15 is on the lower side, and the LED chip (corresponding to a light emitting element) 20 is positioned on the conductive paste 18. Mount with a chip mounter. These LED chips 20 are actually configured by alternately arranging red LED chips, green LED chips, and blue LED chips.

  Next, a plurality of white light diffusion film substrates 21 are laminated on the surface of the wiring film substrate 19 so as to cover the LED chips 20. These light diffusing film substrates 21 have different transmittances so that light passing therethrough is effectively diffused. In this case, a window portion 21a is formed at a position corresponding to the LED chip 20 on the first light diffusion film substrate 21 laminated on the wiring film substrate 19, and the light diffusion film substrate 21 is connected to the wiring substrate 19 by wiring. In the state of being laminated on the film substrate 19, the LED chip 20 is positioned in the window portion 21 a.

Further, the cover layer 22 is laminated on the back surface of the wiring film substrate 19 so as to cover the conductor pattern 15. Here, the elastic modulus of the cover layer 22 is preferably 1 to 1000 MPa. This is because heat welding between films becomes difficult at an elastic modulus higher than that.
(6) Sixth step: Pressurization is performed at 200 to 350 ° C. with a pressure of 0.1 to 10 MPa by a vacuum press machine.

As described above, the multilayer substrate 23 in which the LED chip 20 is incorporated can be manufactured.
Here, in this Embodiment, as shown in FIG. 3, the press temperature in the said 6th process is set to about 200 degreeC. At this temperature, the wiring film substrate 19 and the light diffusion film substrate 21 are melted in an amorphous state, and the thermoplastic resins of the respective layers are integrated by thermal fusion, and the thermoplastic resins of the respective layers are excellent when dissolved. It exhibits excellent adhesive strength, and has excellent characteristics with no delamination even in a multilayer substrate.

  In FIG. 1 showing the manufacturing method of the backlight unit 11, a light shielding member 24 is bonded to the outer peripheral surface of the multilayer substrate 23 manufactured as described above, and a cable 25 with a connector is electrically connected to the conductor pattern 15. Thus, the light source substrate 12 can be manufactured, and the backlight unit 11 can be manufactured by bonding the aluminum plate 13 to the light source substrate 12. The aluminum plate 13 has a function of radiating heat from the light source substrate 12 and reflecting light from the LED chip 20 forward.

When the backlight unit 11 configured as described above is energized, the red LED chip 20, the green LED chip 20, and the blue LED chip 20 are energized through the conductor pattern 15. As shown in FIG. 2, the light is turned on, and light of each color of red, green, and blue passes through the light diffusion film substrate 21. At this time, since the light irradiated backward from the LED chip 20 is reflected by the aluminum plate 13, the light irradiated from the LED chip 20 can be effectively directed forward.
In addition, as energization control with respect to the LED chip 20, in addition to energizing each LED chip 20 simultaneously, you may make it energize to the LED chip of each color in order.

  Here, since the light diffusing film substrate 21 is made of resin films having different transmittances, when light passes and diffuses, the diffusion mode is nonuniform as shown in FIG. As a result, the light emitted to the outside from the light diffusion film substrate 21 is emitted in a non-uniform state, so that red, green, and blue light are well mixed and become white light with no uneven brightness. Irradiated forward.

According to such an embodiment, the wiring film substrate 19 made of the crystalline transition type thermoplastic resin and the light diffusion film substrate 21 are laminated, and pressed in a heated state, whereby the LED chip is placed in the thermoplastic resin. Unlike the conventional example using a cold cathode tube, the backlight unit 11 made of a multilayer substrate 20 is manufactured, so that it is thin and light, has a long life, and is a heavy load substance against nature. A backlight unit that is not used can be manufactured.
In addition, since the multilayer substrate employed in this embodiment is suitable for mass production, cost can be reduced.

(Other embodiments)
The present invention is not limited to the above embodiment, and can be modified or expanded as follows.
Laminating a wiring film substrate on which only a blue LED chip is mounted, a wiring film substrate on which only a green LED chip is mounted, and a wiring film substrate on which only a blue LED chip is mounted White light may be generated by lighting or blinking.

A white LED may be used as the LED chip.
You may make it comprise a reflection member by sticking aluminum foil on the back surface of the cover layer 22 layer, or vapor-depositing aluminum.
You may make it use the prepreg which has a light transmittance between film substrates.

The figure which shows the manufacturing method of the backlight unit in one embodiment of this invention Sectional drawing which shows the board | substrate for light sources typically The figure which shows the relationship between the processing temperature and elastic modulus of a resin film The figure which shows the manufacturing method of the board | substrate for light sources FIG. 2 equivalent diagram showing a conventional example

Explanation of symbols

  11 is a backlight unit, 12 is a light source substrate, 13 is an aluminum plate (reflecting member), 15 is a conductor pattern, 17 is a via hole, 19 is a film substrate for wiring, 20 is an LED chip (light emitting element), and 21 is light diffusion. Film substrate.

Claims (5)

A crystalline transition type thermoplastic resin in which a conductor pattern for wiring is formed on one surface and a via hole is formed at the bottom of the conductor pattern, and the via hole is filled with a conductive material so as to be electrically connected to the conductor pattern. A wiring film substrate made of a resin member;
A light emitting element that is located on the wiring film substrate and is electrically connected to the conductor pattern through the conductive material;
A film substrate for light diffusion which is located on the light emitting element side of the wiring film substrate and is made of a crystalline transition type thermoplastic resin member which diffuses light passing therethrough,
The light units, wherein the film substrates are heat-welded to each other in a form in which the light-emitting elements are buried in a thermoplastic resin by being pressed in a heated state.   The light unit according to claim 1, wherein the light diffusion film substrate includes a plurality of film substrates having different transmittances.   The light unit according to claim 1, wherein the light emitting element is an LED chip.   The light unit according to claim 3, wherein the LED chip is a red LED chip, a green LED chip, or a blue LED chip.   The light unit according to claim 1, further comprising a reflecting member provided on a conductor pattern side of the wiring film substrate.

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