JP4679466B2 - Backlight device - Google Patents

Description

  The present invention relates to a backlight device, and more particularly to an edge light type backlight device.

  The backlight device is used as a light source for a liquid crystal display device or the like. In a liquid crystal display device, a liquid crystal display panel disposed on a light emitting surface of a backlight device performs image switching by performing optical switching for each pixel arranged in a matrix. In the backlight device, a light source is disposed directly under the light emitting surface, a direct type in which light emitted from the light source directly irradiates the back surface of the light emitting surface, a light guide plate directly under the light emitting surface, and an edge of the light guide plate There is an edge light type in which a light source is provided respectively, and light emitted from the light source is guided to a light emitting surface by a light guide plate.

  The edge-light type backlight device is advantageous in reducing the thickness because the light source can be disposed on the side edge of the backlight device. As the light source of the edge light type backlight device, there are a linear cold cathode fluorescent lamp and a chip type light emitting diode (LED), but a chip type LED having a small size and a long lifetime has become the mainstream in recent years. It is becoming.

  FIG. 6 is a cross-sectional view showing a configuration of an edge light type backlight device using such a chip type LED as a light source. In the backlight device 100, the light emitted from the light emitting portion 21a of the LED is, as indicated by the arrow 101, the first reflector 31, the light mixing light guide plate 32, the second reflector 33, the main light guide plate 34, and the optical sheet 35. And exits from the surface of the optical sheet 35 which is the light emitting surface 10a.

  By the way, in a backlight device using LEDs as light sources, red, green, and blue LEDs having high luminance are used in order to cause the light emitting surface 10a to emit white light. In the backlight device 100, the three colors of light emitted from the LEDs 21 are mixed by the light mixing light guide plate 32 to be white light, which is guided to the light emitting surface 10a.

The configuration of the backlight device 100 is described in Patent Document 1, for example.
Japanese Patent Laid-Open No. 2004-199967 (FIG. 2)

  By the way, as the demand for display quality of a liquid crystal display device increases, it is required to make the chromaticity in the light emitting surface of the backlight device more uniform and suppress the color shift on the display surface of the liquid crystal display device. Although the backlight device is designed so that the luminance and chromaticity are uniform within the light emitting surface, in-plane variation in chromaticity on the light emitting surface may occur due to manufacturing variations among individual LEDs. .

  In order to suppress in-plane variations in chromaticity on the light emitting surface, it is conceivable to adjust the luminance of individual LEDs mounted on the LED mounting substrate. However, in general, in the LED mounting substrate, the LEDs are connected in series for each color so that the brightness can be adjusted collectively for each color. For this reason, it is difficult to control the drive voltage of each LED, and a means that can suppress in-plane variation in chromaticity without controlling the LED drive voltage is desired.

  Further, in the conventional backlight device, there is no means for adjusting the brightness of each LED after the LED mounting substrate is attached to the light guide unit. Therefore, when the in-plane variation in chromaticity on the light emitting surface is confirmed after the LED mounting substrate is attached to the light guide unit, it is necessary to remove the LED mounting substrate from the light guide unit and adjust it. It took time and effort. Therefore, after attaching an LED mounting substrate to a light guide unit, a means that can easily suppress in-plane variation in chromaticity on the light emitting surface is desired.

  In view of the above, the present invention provides an edge-light type backlight device, which can easily suppress in-plane variation in chromaticity on a light-emitting surface without disassembling the backlight device. Objective.

In order to achieve the above object, a backlight device according to the present invention includes a plurality of light sources, an incident end face, and a light emitting face, and guides light from the plurality of light sources incident from the incident end face and exiting from the light emitting face. In a backlight device comprising a light plate,
A light-shielding plate that is disposed so as to be able to advance between each of the plurality of light sources and the incident end surface, and controls the amount of light incident on the light guide plate from the light sources ;
The light guide plate is disposed adjacent to the incident end surface, and includes a reflector that accommodates the light source therein and reflects light from the light source toward the incident end surface, and the light shielding plate is disposed on the reflector. Arranged to be able to advance inside,
The shading plate is integrally coupled to the tip portion of a bolt disposed so as to be able to advance with respect to the reflector so as to be rotatable in the rotation direction of the bolt and in the axial direction.
The light shielding plate is inserted into a notch having a shape corresponding to the shape of the bottom surface of the light shielding plate formed in the reflector so that the light shielding plate moves in parallel to the incident end surface of the light guide plate, and The bolt is screwed into a screw hole formed in a substrate on which the light source is mounted .

  According to the present invention, the amount of light incident on the light guide plate from each of the plurality of light sources can be individually controlled by adjusting the amount of advancement of the light shielding plate corresponding to each of the plurality of light sources. Thereby, in-plane variations in luminance and chromaticity on the light emitting surface can be easily suppressed.

  In the present invention, the light guide plate includes a reflector that is disposed adjacent to the incident end surface, accommodates the light source therein, and reflects light from the light source toward the incident end surface, and the light shielding plate May be disposed inside the reflector so as to advance freely.

  In a preferred aspect of the present invention, the light-shielding plate is integrally coupled to a tip portion of a bolt disposed so as to be able to advance with respect to the reflector so as to be rotatable in the rotational direction of the bolt and integrally in the axial direction. Yes. By adjusting the rotation of the bolt, the advancement amount of the light shielding plate can be finely adjusted.

  In the present invention, the plurality of light sources may include light sources that emit light at different wavelengths. The chromaticity of the light emitting surface can be easily adjusted.

  In the present invention, the light guide plate has the light emitting surface and a main light plate disposed on the back surface of the liquid crystal display panel, the incident end surface, and disposed on the back surface of the main light plate, the main light plate, A light mixing light guide plate optically coupled by a reflector may be provided. A small backlight device can be realized.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view illustrating a configuration of a backlight device according to an embodiment of the present invention. The backlight device 10 is an edge light type backlight device, and has the same configuration as the backlight device 100 of FIG. 6 except that the configuration near the first reflector 31 is different.

  The backlight device 10 includes an LED mounting substrate 11 that includes a large number of LEDs 21 that are aligned and aligned in a direction perpendicular to the paper surface, and a light guide unit 12 that guides light emitted from the LEDs 21 to a light emitting surface 10a. The LED 21 includes a light emitting unit 21 a that emits red, green, or blue light, and is mounted on a substrate body 22 that includes a circuit that supplies power to the LED 21. A circuit for supplying power to the LED 21 is wired in series for each color.

  The light guide unit 12 is disposed on the front surface of the light emitting unit 21a of the LED, reflects the light emitted from the light emitting unit 21a and changes the traveling direction by 90 °, and the light from the first reflector 31. A rectangular light mixing light guide plate 32 that is incident on the incident end face and mixed and then emitted from the outgoing end face is provided. Further, the second reflector 33 having a semi-cylindrical shape that reflects the light emitted from the emission end face of the light mixing light guide plate 32 and changes its traveling direction by 180 °, and the front side of the light mixing light guide plate 32 are provided. And a rectangular main light plate 34 that allows the light from the second reflector 33 to be incident from the incident end face and to be emitted from the light emitting surface 10a.

  A reflection sheet (not shown) is disposed on the back surface of the main light guide plate 34. The reflection sheet reflects the light traveling toward the back side of the main light plate 34 to the front side of the main light plate 34. A plurality of optical sheets 35 are disposed on the front side of the main light guide plate 34. The optical sheet 35 diffuses the light incident from the main light plate 34, and improves the luminance and luminance uniformity on the light emitting surface 10a.

  FIG. 2 is an enlarged cross-sectional view showing a part of the portion II including the LED mounting substrate 11 of FIG. The first reflector 31 has a plate-shaped first portion 31a disposed on an extension of the rear surface of the light mixing light guide plate 32 and a first portion 31a having an arc-shaped cross section disposed to face the light emitting portion 21a of the LED. And two portions 31b. The second portion 31 b is formed with a circular notch for accommodating the light emitting portion 21 a of the substantially hemispherical LED in the first reflector 31.

  In the substrate body 22, a substantially rectangular light shielding plate 24 whose protruding position is adjusted by a screw 23 is disposed between each LED 21 and the light mixing light guide plate 32. Each light shielding plate 24 is arranged in parallel to the incident end face of the light mixing light guide plate 32. Further, a part thereof is accommodated in a light shielding plate accommodation hole 26 formed on the front side of the substrate body 22. A part of the screw 23 is screwed into a screw hole 25 formed on the back side of the substrate body 22 continuously to the light shielding plate accommodation hole 26. The screw 23 and the light shielding plate 24 are integrally coupled in the axial direction of the screw 23 so as to be rotatable in the rotational direction of the screw 23. A rectangular notch corresponding to the shape of the bottom surface of the light shielding plate 24 is formed in the second portion 31b of the first reflector.

  FIGS. 3A and 3B are plan views showing configurations of the LED mounting substrate 11 in FIG. 1 viewed from the front side and the back side, respectively. On the front surface of the LED mounting substrate 11, a plurality of LEDs 21 are arranged at equal intervals, and a light shielding plate 24 is arranged corresponding to the plurality of LEDs 21. In the arrangement of the LEDs 21, red, green, and blue LEDs 21 are sequentially and repeatedly arranged. On the back surface of the LED mounting board 11, screws 23 are arranged corresponding to the plurality of light shielding plates 24 arranged in front of the LED mounting board 11. FIG. 4 is a plan view showing the configuration of the light guide unit 12 in FIG. 1 viewed from the back side. In the light guide unit 12, a plurality of notches 36 and notches 37 are disposed corresponding to the plurality of LEDs 21 and the light shielding plate 24, respectively.

  In the use state of FIG. 2, the front edge of the light shielding plate 24 is at the rear of the second portion 31b. In this use state, the light shielding plate 24 does not block the light emitted from the LED 21.

  FIG. 5 is a cross-sectional view showing another use state of the backlight device 10 in a cross section corresponding to FIG. By rotating the screw 23 using a screwdriver or the like and moving the screw 23 forward, the light shielding plate 24 can be protruded into the first reflector 31. When the light shielding plate 24 protrudes into the first reflector 31, the notch 37 formed in the first reflector 31 restricts the direction of the light shielding plate 24 in a direction parallel to the incident end face of the light mixing light guide plate 32. To do. The light shielding plate 24 protruding into the first reflector 31 blocks part of the light emitted from the light emitting portion 21a of the LED.

  When the screw 23 is rotated in the opposite direction, the light shielding plate 24 can be moved to the outside of the first reflector 31 by the backward movement of the screw 23. By adjusting the rotation of the screw 23, the amount of projection of the light shielding plate 24 into the first reflector 31 can be adjusted, and the amount of light shielding can be finely controlled.

  According to the backlight device 10 of the present embodiment, by adjusting the protruding amount of each light shielding plate 24 into the first reflector 31 using the screw 23, it is emitted from each LED 21 and enters the light mixing light guide plate 32. The amount of light to be controlled can be controlled arbitrarily and independently of each other. Thereby, the light quantity of each LED21 can be adjusted and the in-plane dispersion | variation in the light emission surface 10a can be suppressed, without disassembling the backlight apparatus 10. FIG. Moreover, since the light quantity of each LED21 can be adjusted in the state assembled to the backlight apparatus 10, the design conditions of the backlight apparatus 10 can be loosened.

  The light quantity of each LED 21 can be adjusted easily and with high accuracy because the light emitting surface 10a can be observed on the spot while observing the light emitting surface 10a visually. In addition, since adjustment can be performed in a state where the liquid crystal display panel is integrated with the liquid crystal display device, the uniformity of luminance and chromaticity within the display surface of the liquid crystal display device can be easily improved.

  In the above embodiment, the light shielding plate 24 is coupled to the screw 23. However, any member other than the screw 23 can be used as long as it can move in a direction orthogonal to the surface of the substrate body 22 and can be locked at a predetermined position. You may couple | bond with this member. Moreover, the arrangement | positioning position of the light-shielding plate 24 is not limited above, For example, it is good also as a structure which provides a space between the 1st reflector 31 and the light-guide plate 32 for light mixing, and protrudes in the space.

  Furthermore, in the above-described embodiment, an example of the backlight device in which the light mixing light guide plate 32 is disposed on the back side of the main light guide plate 34 is shown. However, the light mixing light guide plate 32 is integrated on the extension of the main light guide plate 34. The present invention can be similarly applied to a backlight device arranged in a similar manner. A heat sink may be disposed on the back surface of the LED mounting substrate 11 via grease or the like.

  Although the present invention has been described based on the preferred embodiment, the backlight device according to the present invention is not limited to the configuration of the above embodiment, and various modifications and changes can be made to the configuration of the above embodiment. Modified backlight devices are also included in the scope of the present invention.

It is sectional drawing which shows the structure of the backlight apparatus which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows a part of part II of FIG. FIGS. 3A and 3B are plan views showing configurations of the LED mounting substrate of FIG. 1 viewed from the front side and the back side, respectively. It is a top view which shows the structure which looked at the light guide unit of FIG. 1 from the back side. It is sectional drawing which shows another use condition of the backlight apparatus of FIG. 1 in the cross section corresponding to FIG. It is sectional drawing which shows the structure of the conventional backlight apparatus.

Explanation of symbols

10: Backlight device 10a: Light emitting surface 11: LED mounting substrate 12: Light guide unit 21: LED
21a: (LED) light emitting unit 22: substrate body 23: screw 24: light shielding plate 25: screw hole 26: light shielding plate accommodation hole 31: first reflector 31a: first portion 31b of the first reflector: first of the first reflector 2 part 32: light mixing light guide plate 33: second reflector 34: main light plate 35: optical sheet 36: notch 37: notch

Claims (3)

In a backlight device comprising a plurality of light sources, and a light guide plate that has an incident end face and a light emitting surface and that emits light of the plurality of light sources from the incident end face and emits the light from the light emitting face.
A light-shielding plate that is disposed so as to be able to advance between each of the plurality of light sources and the incident end surface, and controls the amount of light incident on the light guide plate from the light sources ;
The light guide plate is disposed adjacent to the incident end surface, and includes a reflector that accommodates the light source therein and reflects light from the light source toward the incident end surface, and the light shielding plate is disposed on the reflector. Arranged to be able to advance inside,
The shading plate is integrally coupled to the tip portion of a bolt disposed so as to be able to advance with respect to the reflector so as to be rotatable in the rotation direction of the bolt and in the axial direction.
The light shielding plate is inserted into a notch having a shape corresponding to the shape of the bottom surface of the light shielding plate formed in the reflector so that the light shielding plate moves parallel to the incident end surface of the light guide plate, and The backlight device, wherein the bolt is screwed into a screw hole formed in a substrate on which the light source is mounted .   The backlight device according to claim 1, wherein the plurality of light sources include light sources that emit light at different wavelengths. The light guide plate has the light emitting surface and is disposed on the back surface of the liquid crystal display panel, and has the incident end surface. The light guide plate is disposed on the back surface of the light guide plate and is optically coupled with the light guide plate and the reflector. The backlight apparatus of Claim 2 provided with the light-guide plate for light mixing couple | bonded with.

Images