JP4605465B2 - Backlight module and liquid crystal display device - Google Patents

Description

  The present invention relates to a backlight module and a liquid crystal display device. In particular, the present invention relates to a backlight module capable of adjusting a color temperature and a liquid crystal display device employing the backlight module.

  With the significant improvement in computer performance and the advanced development of the Internet and multimedia technology, the transmission method of image information has shifted from an analog method to a digital method. In addition, visual information devices and image devices are becoming lighter and thinner in accordance with modern lifestyles. A conventional display device using a cathode ray tube still has its advantages. However, since an electron beam deflection space is required inside the display device, the entire display device becomes large and occupies a large space. In addition, since the image display is performed by electron beam irradiation, there is a problem that the eyes of the user are tired. Therefore, flat display devices developed by combining photoelectric technology and semiconductor manufacturing technology, for example, liquid crystal display devices, organic EL display devices, and plasma display devices are already becoming mainstream of display devices.

  Depending on the method of use of the light source, the liquid crystal display device can be a reflective liquid crystal display device (Reflective LCD), a transmissive liquid crystal display device (Transmissive LCD), or a transflective liquid crystal display device (Semi-Transmissive LCD). ) Can be roughly divided into three types. A transmissive liquid crystal display device and a transflective (semi-reflective) liquid crystal display device mainly include a liquid crystal panel and a backlight module. The liquid crystal panel includes two transparent substrates and a liquid crystal layer filled between the two transparent substrates. On the other hand, the backlight module functions as a surface light source required by the liquid crystal panel. With this structure, the liquid crystal display device has an image display function. Backlight modules are roughly classified into two types, a direct type and an edge light type.

  FIG. 1A is a cross-sectional view showing a conventional direct type backlight module. As shown in FIG. 1A, a conventional direct type backlight module 100a mainly includes a casing 110, a plurality of cold cathode fluorescent lamps (CCFLs) 120, a light diffusion plate 130, and an optical film 140. The cold cathode fluorescent tube 120 is disposed in the housing 110. The light irradiated from the cold cathode fluorescent tube 120 is diffused in the initial stage in the housing 110, passes through the light diffusion plate 130 and the optical film 140, and is irradiated in a planar shape from the surface of the optical film 140 to the outside. Is done.

  FIG. 1B is a cross-sectional view illustrating a conventional edge light type backlight module. As shown in FIG. 1B, the conventional edge light type backlight module 100b mainly includes a light guide plate 150, a cold cathode fluorescent tube 120, a lamp cover 160, and an optical film 140. The light guide plate 150 includes a light incident surface 152 and a light emitting surface 154. The cold cathode fluorescent tube 120 is disposed in the vicinity of the light incident surface 152 of the light guide plate 150 and is located in the lamp cover 160. The optical film 140 is disposed on the light exit surface 154 of the light guide plate 150.

  As shown in FIG. 1B, the light emitted from the cold cathode fluorescent tube 120 is reflected directly or by the lamp cover 160 and enters the light guide plate 150 from the light incident surface 152, and the light exit surface of the light guide plate 150. Irradiated from 154. The light guide plate 150 is for irradiating the light emitted from the cold cathode fluorescent tube 120 in a planar shape.

  In the two types of backlight modules described above, the cold cathode fluorescent tube functions as a white light source. A white light source gives a different vision to the human eye due to the difference in color temperature. For example, when the color temperature of the white light source is high, the display screen approaches blue. On the other hand, when the color temperature of the white light source is low, the display screen approaches yellow. Therefore, there is a need for a technique that can adjust the color temperature of the light source of the backlight module according to the user's preference and the like.

When a display (white) light source with a high color temperature is required, in order to increase the color temperature of the light source, for example, the ratio of blue fluorescent powder in a cold cathode fluorescent tube must be increased. In addition, if the color temperature of the cold cathode fluorescent tube is increased in this way, the luminous efficiency of the cold cathode fluorescent tube is lowered.
In the conventional backlight module, the color temperature cannot be adjusted unless the cold cathode fluorescent tube is replaced. Further, even if the color temperature is adjusted by replacing the cold cathode fluorescent tube, it is inevitable that the luminance of the backlight module is lowered.
The present invention solves the above problems. The present invention provides a technique that enables adjustment of both luminance and color temperature.

The backlight module according to the technique of the present invention includes a main light source and a color temperature adjusting light source. The color temperature of the main light source and the color temperature of the color temperature adjusting light source are different from each other.
In this backlight module, the luminance of display light is mainly ensured by the main light source. Then, the color temperature of the display light is adjusted by the color temperature adjusting light source.
The technology of the present invention is effective for a direct type backlight module and also for an edge light type backlight module.
A direct type backlight module embodied by the technology of the present invention includes a housing having at least one opening, a plurality of main light sources disposed in the housing, and a plurality of color temperature adjustments disposed in the housing. A light source and a light diffusing plate disposed in the vicinity of the opening of the housing are provided. Both the plurality of main light sources and the plurality of color temperature adjustment light sources are disposed immediately below the openings in the housing. The color temperature of the main light source and the color temperature of the color temperature adjusting light source are different from each other.

The main light source preferably generates white light, and more preferably a cold cathode fluorescent lamp. In addition, it is preferable to use a light emitting diode as the color temperature adjusting light source. As the light emitting diode, a blue light emitting diode, a red light emitting diode, or a green light emitting diode can be used. In this case, only a single color light emitting diode can be used, or a plurality of color light emitting diodes can be used in combination.
In the above backlight module, the plurality of main light sources can be disposed between the plurality of color temperature adjustment light sources and the light diffusion plate. In this case, each main light source can be disposed immediately above each color temperature adjustment light source. Alternatively, the main light source and the color temperature adjusting light source can be alternately arranged along the direction in which the light diffusion plate spreads.
In the above backlight module, it is preferable to add an optical film provided on the light diffusion plate.
In the above backlight module, it is preferable to add a reflection sheet provided at the bottom of the housing.

  An edge light type backlight module embodied by the technology of the present invention includes a light guide plate having a light incident surface and a light output surface, at least one main light source disposed on the light incident surface side of the light guide plate, And at least one color temperature adjusting light source disposed on the light incident surface side of the light guide plate. The color temperature of the main light source and the color temperature of the color temperature adjusting light source are different from each other.

In the above backlight module, it is preferable that a lamp cover provided in the vicinity of the light incident surface is added. In this case, it is preferable that the main light source and the color temperature adjusting light source are disposed in the lamp cover.
In said backlight module, it is preferable that the optical film provided in the light-projection surface side of the light-guide plate is added.

  Another backlight module embodied by the present invention is a backlight module that provides display light to a liquid crystal display panel, and includes at least one main light source and at least one color temperature adjusting light source. The color temperature of the main light source and the color temperature of the color temperature adjusting light source are different from each other.

  Another backlight module embodied by the present invention includes a housing having at least one opening, at least one cold cathode fluorescent lamp disposed in the housing, and at least disposed in the housing. One light emitting diode is provided.

  The technology of the present invention can realize a new and useful liquid crystal display device. This liquid crystal display device includes a liquid crystal panel and any one of the backlight modules described above.

  The backlight module of the present invention includes a main light source that provides display light with sufficient luminance and a color temperature adjustment light source that adjusts the color temperature of the display light, so that both the luminance of the display light and the color temperature are achieved. be able to. In the liquid crystal display device adopting the present invention, even when a dark screen or a low gradation screen is displayed, the screen does not approach blue, and the display quality is improved.

In order to further clarify the objects, features, and advantages of the present invention, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 2A is a cross-sectional view showing the backlight module 200 according to the first embodiment of the present invention. As shown in FIG. 2, the backlight module 200 is a direct type backlight module, and includes a housing 210, a main light source set 220, a color temperature adjustment light source set 230, and a light diffusion plate 240. The housing 210 has an opening 212. The light diffusion plate 240 is disposed in the vicinity of the opening 212 of the housing 210. Both the main light source set 220 and the color temperature adjusting light source set 230 are arranged in the housing 210.

In the backlight module 200, the main light source set 220 is a light source body for irradiating white light. The main light source set 220 includes, for example, at least one cold cathode fluorescent lamp 222. FIG. 2 illustrates a configuration including a plurality of cold cathode fluorescent lamps 222. In addition, each light source (cold cathode fluorescent lamp) 222 of the main light source set 220 can be changed to another light emitter that can provide white light.
The light source set 230 for color temperature adjustment includes, for example, at least one light emitting diode 232. FIG. 2 illustrates a mode including a plurality of light emitting diodes 232. As the light emitting diode 232, for example, a blue light emitting diode, a red light emitting diode, or a green light emitting diode can be used. At this time, only light emitting diodes of the same color may be used, or light emitting diodes of different colors may be used in combination. In the following description, a blue light emitting diode is used as the light emitting diode 232.

  In the backlight module 200, the main light source set 220 is a white light source that generates white light, and the color temperature adjustment light source set 230 is a blue light source that generates blue light. The two types of light source sets 220 and 230 constitute a light source of the backlight module 200. Light emitted from the two types of light source sets 220 and 230 is mixed in the housing 210, diffused when passing through the light diffusion plate 230, and uniformly irradiated to the outside. Thereby, the backlight module can be employed as a surface light source for uniformly illuminating a liquid crystal panel or the like.

In the backlight module 200, at least one optical film can be disposed on the light diffusion plate 240. Thereby, the uniformity of the light irradiated by the backlight module 200 can be further improved.
In the backlight module 200, a reflection sheet 260 that reflects light emitted from the main light source set 220 and the color temperature adjustment light source set 230 can be disposed at the bottom of the housing 210. Thereby, the light emitted from the main light source set 220 and the color temperature adjusting light source set 230 can be efficiently incident on the light diffusion plate 240. Thereby, the luminous efficiency of the backlight module 200 can be further improved.

  As shown in FIG. 2A, the main light source set 220 can be disposed between the color temperature adjusting light source set 230 and the light diffusion plate 240, for example. At this time, each light source (cold cathode fluorescent lamp) 222 of the main light source set 220 can be disposed immediately above each light source (light emitting diode) 232 of the color temperature adjusting light source set 230, for example. Alternatively, as shown in FIG. 2B, the respective light sources 222 of the main light source set 220 and the respective light sources 232 of the color temperature adjusting light source set 230 can be arranged alternately. According to the former arrangement shown in FIG. 2A, the light emission uniformity of the backlight module 200 can be improved. On the other hand, according to the latter arrangement shown in FIG. 2B, the light emission efficiency of the backlight module 200 can be increased.

  In the backlight module 200, since the color temperature of the monochromatic light emitted from the light source 232 of the color temperature adjustment light source set 230 and the color temperature of the white light emitted from the main light source set 220 are different, the light emitted from the backlight module 200 The color temperature is compensated. When it is necessary to adjust the color temperature of light emitted from the backlight module 200, the intensity of monochromatic light emitted from the light source 232 of the color temperature adjustment light source set 230 may be adjusted. Since it is not necessary to replace the cold cathode fluorescent lamp 222, the luminous efficiency of the entire backlight module 200 is not affected. In the backlight module 200, the cold cathode fluorescent lamp 222 having high light emission efficiency is used, and the color temperature can be compensated by the blue light source, so that light with high luminance and appropriate color temperature can be irradiated. .

  According to the backlight module 200 of the present embodiment, when a low gradation screen or a dark screen is displayed by the liquid crystal display device, the color temperature is adjusted by the light emitting diode 232 to avoid the screen from being blue. be able to. Further, when a low gradation screen or a dark screen is displayed in a part of the screen, it is possible to adjust the light emission intensity of only the light emitting diode 232 corresponding to the range. By using the backlight module 200 as the light source of the liquid crystal display device, it is possible to correctly display a low gradation screen.

  In the backlight module, a light emitting diode of another color can be used as the light source 232 of the color temperature adjusting light source set 230 in place of the blue light emitting diode as described above. For example, the color temperature adjusting light source set 230 can be configured using at least one red light emitting diode. Alternatively, at least one green light emitting diode can be used. Alternatively, a blue light emitting diode and a red light emitting diode can be arbitrarily combined. Alternatively, a blue light emitting diode and a green light emitting diode can be arbitrarily combined. Alternatively, a green light emitting diode and a blue light emitting diode can be arbitrarily combined. Alternatively, a blue light emitting diode, a green light emitting diode, and a red light emitting diode can be arbitrarily combined.

  FIG. 3 is a graph showing an optical adjustment signal for the backlight module 200. L1 in FIG. 3 indicates a light adjustment signal for each light source (cold cathode fluorescent lamp) 222 of the main light source set 220. L2 in FIG. 3 indicates a light adjustment signal for each light source (light emitting diode) 232 of the color temperature adjustment light source set 230. As shown in FIG. 3, when the backlight module 200 is operated, the emission intensity is adjusted by pulse width modulation for each light source 222 of the main light source set 220 and each light source 232 of the color temperature adjustment light source set 230. Is called. In the backlight module 200, the light emission intensity of each light source 232 of the color temperature adjustment light source group 230 can be adjusted by the pulse width d of L2 in the drawing, and thereby the color temperature can be adjusted. At this time, in order to eliminate instantaneous color temperature unevenness at the time of startup, for example, it is preferable to synchronize the light adjustment signals L1 and L2 at the time of startup. Thereby, stable illumination light can be provided.

(Second Embodiment)
FIG. 4 is a cross-sectional view showing the backlight module of the second embodiment. As shown in FIG. 4, the backlight module 300 of the second embodiment is a single edge light type backlight module, and mainly includes a light guide plate 310, a main light source set 320, and a color temperature adjustment light source set 330. I have. The light guide plate 310 has a light incident surface 312 and a light emitting surface 314. The main light source set 320 and the color temperature adjustment light source set 330 are located on the side of the light guide plate 310 and are arranged in the vicinity of the light incident surface 312.

  In the backlight module 300 of the second embodiment, the main light source set 320 can be configured using, for example, at least one cold cathode fluorescent lamp. The color temperature adjusting light source set 330 can be configured using, for example, at least one light emitting diode 332. For example, a blue light emitting diode, a red light emitting diode, or a green light emitting diode can be used as the light emitting diode. When using a plurality of light emitting diodes, the light emitting diodes of the same color may be used, or light emitting diodes of different colors may be used in combination. In the following description, a blue light emitting diode is used as the light emitting diode 332.

In the backlight module 300, the main light source set 320 is a white light source that emits white light, and the color temperature adjustment light source set 330 is a monochromatic light source that emits monochromatic light (here, blue light). The two types of light source sets 320 and 330 constitute a light source of the backlight module 300. The light emitted from the two types of light source sets 320 and 330 enters the light guide plate 310 from the light incident surface 312 of the light guide plate 310, is mixed in the light guide plate 310, and is uniformly irradiated from the light exit surface 314. The Thereby, the backlight module 300 can be employed as a surface light source for uniformly illuminating the liquid crystal panel.
In the backlight module 300, it is preferable to arrange a lamp cover 340 that reflects light so as to surround the outside of the main light source set 320 and the color temperature adjustment light source set 330. Thereby, the light emitted from the main light source set 320 and the color temperature adjusting light source set 330 can be efficiently incident on the light guide plate 310. The light emission efficiency of the backlight module 300 can be improved.
In the backlight module 300, for example, at least one optical film 350 can be disposed in the vicinity of the light emitting surface 314 of the light guide plate 310. Thereby, the uniformity of the light irradiated by the backlight module 300 can be further improved.

  FIG. 5 shows a double edge light type backlight module 300a which is a modification of the present embodiment. As shown in FIG. 5, in the double edge light type backlight module 300a, the light guide plate 310a has, for example, two light incident surfaces 312 facing each other, and the main light source set 320 and the color temperature adjustment light source set 330 These are disposed in the vicinity of the two light incident surfaces 312. Such a double edge light type backlight module can provide a display light source with higher luminance than a single edge light type backlight module.

  The backlight modules 300 and 300 a provide a display light source having sufficient luminance by the main light source set 320 and adjust the color temperature of the display light source by the color temperature adjustment light source set 330. Thereby, it is possible to realize both the luminance of the display light source and the color temperature. Since the driving of the backlight modules 300 and 300a, the light adjustment method, and the adjustment of the luminance and color temperature applied to the display light source are the same as those in the first embodiment, a detailed description thereof will be omitted.

(Third embodiment)
FIG. 6 is a cross-sectional view showing the liquid crystal display device of the third embodiment. As shown in FIG. 6, the liquid crystal display device 400 of this embodiment includes a liquid crystal panel 410 and a backlight module 420. The backlight module 420 is disposed on one side of the liquid crystal panel 410 and provides a display light source 422 required by the liquid crystal panel 410. The liquid crystal panel 410 includes, for example, an upper substrate 412, a lower substrate 414, and a liquid crystal layer 416. As the backlight module 420, the backlight module described in the first embodiment or the second embodiment is used. That is, the backlight module 420 can adjust the color temperature of the display light.

  The backlight module 420 employed in the liquid crystal display device 400 of the present embodiment is a backlight module that can adjust the color temperature of the display light source 422, and therefore displays a dark screen or a low gradation screen. Is less likely to cause the screen to turn blue. Thereby, the liquid crystal display device 400 of this embodiment can achieve high display quality.

  As described above, the backlight module embodying the present invention includes both the main light source set and the color temperature adjusting light source set. The main light source group mainly provides display light having a necessary luminance. On the other hand, the color temperature adjustment light source group adjusts the color temperature of the display light. According to the backlight module embodying the present invention, it is possible to provide display light in which sufficient luminance and color temperature are appropriately adjusted.

  In addition, since the liquid crystal display device embodying the present invention employs a backlight module capable of adjusting both sufficient luminance and color temperature, the screen can be displayed even when a dark screen or a low gradation screen is displayed. Is less likely to turn blue. Thereby, the liquid crystal display device which implemented this invention can implement | achieve high display quality.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in this specification or the drawings achieves a plurality of objects at the same time, and achieving one of the objects itself has technical utility.

Sectional drawing which shows the conventional direct type | mold backlight module. Sectional drawing which shows the conventional edge light type backlight module. Sectional drawing which shows the backlight module of 1st Embodiment. Sectional drawing which shows the modification of the backlight module of 1st Embodiment. The graph which shows the light adjustment signal concerning a cold cathode fluorescent tube and a light emitting diode. Sectional drawing which shows the backlight module of 2nd Embodiment. Sectional drawing which shows the modification of the backlight module of 2nd Embodiment. Sectional drawing which shows the liquid crystal display device of 3rd Embodiment.

Explanation of symbols

100a, 100b, 100c ... Backlight modules 200, 300, 300a ... Backlight modules 110, 210 ... Housing 120, 222 ... Cold cathode fluorescent tube 130, 240 ... Light diffusion plates 140, 250, 350 ... Optical films 150, 310, 310a Light guide plates 152, 312 Light incident surfaces 154, 314 Light output surfaces 160, 340 Lamp covers 170, 232, 332 Light emitting diodes 212 Opening 220 320 ·· Main light source set 230, 330 · · Color temperature adjustment light source set 260 · · Reflection sheet 400 · · Liquid crystal display device 410 · · Liquid crystal panel 412 · · Upper substrate 414 · · Lower substrate 416 · · Liquid crystal layer 420 · · Back Light module 422 .. display light source L1, L2 ..light adjustment signal

Claims (8)

A housing having at least one opening;
A main light source group disposed in the housing and generating white light;
A color temperature adjusting light source set that is disposed in the housing and generates colored light;
A light diffusing plate disposed in the vicinity of the opening of the housing;
The main light source set includes a plurality of cold cathode fluorescent lamps,
The color temperature adjusting light source set includes a plurality of light emitting diodes,
A direct-type backlight module in which both the plurality of cold cathode fluorescent lamps and the plurality of light-emitting diodes are disposed directly below the opening in the housing.   The backlight module according to claim 1, wherein the light emitting diode is one of a blue light emitting diode, a red light emitting diode, and a green light emitting diode.   The backlight module according to claim 1, wherein the main light source group is located between the color temperature adjusting light source group and the light diffusion plate.   4. The backlight module according to claim 3, wherein the cold cathode fluorescent lamp of the main light source group is located immediately above the light emitting diode of the color temperature adjusting light source group.   4. The back according to claim 1, wherein the cold cathode fluorescent lamps of the main light source set and the light emitting diodes of the color temperature adjusting light source set are alternately positioned along a direction in which the opening is widened. 5. Light module. A housing having at least one opening;
A plurality of cold cathode fluorescent lamps arranged in the housing and generating white light;
A plurality of light emitting diodes arranged in the housing and generating colored light as a whole ;
A direct-type backlight module in which both the plurality of cold cathode fluorescent lamps and the plurality of light-emitting diodes are disposed directly below the opening in the housing. LCD panel,
A backlight module disposed on one side of the liquid crystal panel;
The backlight module has a housing having at least one opening, a plurality of cold cathode fluorescent lamps disposed in the housing and generating white light, and disposed in the housing and colored as a whole. A plurality of light-emitting diodes that generate light, and the plurality of cold-cathode fluorescent lamps and the plurality of light-emitting diodes are direct-type backlight modules arranged directly below the opening in the housing; A liquid crystal display device. LCD panel,
A backlight module disposed on one side of the liquid crystal panel;
The backlight module includes a housing having at least one opening, a main light source set that is disposed in the housing and generates white light, and a color temperature that is disposed in the housing and generates colored light. An adjustment light source set and a light diffusing plate disposed in the vicinity of the opening of the housing; the main light source set includes a plurality of cold cathode fluorescent lamps; and the color temperature adjustment light source set includes a plurality of light emitting diodes. The liquid crystal display device is characterized in that both the cold cathode fluorescent lamp and the light emitting diode are a direct type backlight module arranged in the casing immediately below the opening.

Images