JPH1062627A - Illumination light adjusting structure for display part, and display device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to freely adjust illumination light for a display part with no modifications of an electric circuit. SOLUTION: The illumination light adjusting structure for a display part is arranged on the rear side of the display unit of a liquid crystal display device, etc., and provided with a light-introducing member 2 on the back side of which diffusion prints 6 are made, a reflecting sheet 4 provided on the rear side of the light-introducing member 2, a reflecting tapes 5 provided around the light- introducing member 2, and a light source 1 part which is arranged along one end part of the light-introducing member 2 and formed into columnar shape to illuminate the display unit from the back side. Further, a light-reducing member 7 formed into a cylinder to cover the outer peripheral-circumferential surface of the light source 1 part so that the light reducing rate is different in the circumferential direction, and a turning part 8 for turning the light- reducing member 7, are provided. By turning the light-reducing member 7 by the turning part 8, the light going from the light source 1 part toward the end face of the light-guiding member 2 transmits the light-reducing member 7 to continuously change the light reducing rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for adjusting illumination light by a backlight for a display unit such as a liquid crystal display device, and a display device using such an illumination light adjustment structure for a display unit.

[0002]

2. Description of the Related Art In recent years, liquid crystal televisions and the like using liquid crystals as display devices have been put to practical use. Liquid crystals are suitable for portable use because they are thin, lightweight and have low power consumption. However, since the liquid crystal is a light receiving element, a backlight for illumination is required.
Conventionally, a fluorescent tube is used as a backlight. However, since the fluorescent tube has a cylindrical shape, light is emitted only from the fluorescent tube portion, and uniform light does not reach the entire liquid crystal display screen. Therefore, there is a direct-type backlight in which a reflective case and a reflective sheet are provided so that the light source emitted from the fluorescent tube can be entirely distributed in order to uniformly spread the light over the entire liquid crystal display screen. In addition, for the purpose of thinning, a straight fluorescent tube is arranged on the side end surface of the transparent light guide, and an edge light type backlight using one surface as a surface light source using multiple reflection inside the light guide is also available. is there.

FIG. 5 is an exploded perspective view showing an example of a conventional edge light type backlight unit. In the figure, reference numeral 1 denotes a fluorescent tube (cold cathode ray tube) as a light source, and 2 denotes an acrylic plate (transparent light guide member). Reference numeral 3 denotes a reflector, 4 denotes a reflection sheet, 5 denotes a reflection tape, and 6 denotes diffusion printing provided on the back surface of the acrylic plate 2. As shown in the drawing, the edge light type backlight unit directly reflects the light emitted from the straight fluorescent tube 1 and reflects the light by the reflector 3 so that the light is incident on the acrylic plate 2 from the side end surface. Acrylic board 2
The light emitted from the front surface of the acrylic plate 2 is substantially uniform by being reflected by the reflection sheet 4 on the back side and the reflection tapes 5, 5, 5 around the acrylic plate 2 and diffused by the diffusion printing 6 on the back surface of the acrylic plate 2. It illuminates a liquid crystal display panel (not shown) almost uniformly. The diffusion printing 6 on the back of the acrylic plate 2 is, as shown in FIG.
The gradation is applied so that it becomes denser as it gets away from the object and becomes sparser as it gets closer to the fluorescent tube 1.
Thereby, the liquid crystal display screen is uniformly illuminated. In addition, as the surface area of the diffusion print 6 is larger, the probability that the light from the fluorescent tube 1 shines is increased, and the amount of light emitted from the front surface of the acrylic plate 2 is also increased. As a result, the brightness of the liquid crystal display screen is increased.

[0004] In a liquid crystal television having such an edge light type backlight unit, particularly in a vehicle-mounted liquid crystal television, the brightness of the backlight is adjusted between daytime and nighttime in accordance with the difference in ambient brightness. Is often done. In other words, the backlight is brightened during the day so that the screen can be seen even when the surroundings are bright, and the backlight is darkened at night to prevent the screen from being too bright because the surroundings are dark. As a method conventionally used for dimming the backlight, a light source circuit for lighting the fluorescent tube 1 includes, for example, intermittently oscillating the fluorescent tube 1 or changing the current to change the current. The backlight is dimmed by providing an inverter function for dimming the light and electrically darkening the fluorescent tube 1.

[0005]

However, in order to reduce light with one inverter circuit, various technical and
Due to electrical constraints, 40-50 brightness for bright
Percent dimming has been considered the limit. In recent years, a screen having good visibility even under bright daylight conditions has been demanded, and the brightness of the backlight has been increasing, so that the brightness at the time of dimming has also become bright. However, it was difficult to say that proper luminance was always obtained at night.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an illumination light adjusting structure for a display unit which can freely adjust illumination light for the display unit without changing an electric circuit. Another object of the present invention is to provide a display device using such an illumination light control structure for a display unit.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the invention according to claim 1 is, for example, a structure for adjusting illumination light by a backlight or the like for a display unit such as a liquid crystal display device. For illuminating from the back side, for example, a cylindrical light source, such as a straight tube fluorescent tube, and a cylindrical shape surrounding the circumference of the light source are formed to be continuously dimmed in the circumferential direction. For example, a configuration is provided that includes a dimming member having a different ratio, such as a cylindrical dimming filter, and a rotating portion such as an adjustment knob for rotating the dimming member. And

[0008] As described above, the dimming is realized by forming a cylindrical shape that covers the circumference of the cylindrical light source unit that illuminates the display unit from the back side, and continuously changing the dimming rate in the circumferential direction. Since the illumination light adjusting structure includes a rotating member for rotating the dimming member, the rotating dimming member is rotated by the rotating portion, so that the light source unit is moved to the back of the display unit. The outgoing light passes through the dimming member, and the dimming rate changes continuously. Therefore, the illumination light for the display unit can be freely adjusted, and there is no need to change the electric circuit.

According to a second aspect of the present invention, there is provided a display device such as a liquid crystal display device, which is characterized by using the illumination light control structure of the display unit according to the first aspect.

As described above, since the display device uses the illumination light adjusting structure of the display unit according to the first aspect, the function of the illumination light adjusting structure of the display unit according to the first aspect can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an illumination light control structure for a display unit and a display device using the same according to the present invention will be described below with reference to FIGS. First, FIG. 1 is an exploded perspective view showing a display unit and a backlight as an example to which the present invention is applied, and FIG. 2 is an exploded perspective view showing components of the backlight. FIG. 3 is a partially cutaway side view showing the configuration of the dimming member and the rotating portion of the backlight of FIG. 1, and FIG. 4 is the same view of the portion including the dimming member and the rotating portion of the backlight. It is a top view.

In FIG. 1 to FIG. 4, similar to the above-described conventional example (see FIG. 5), 1 is a fluorescent tube (cold cathode ray tube) as a light source, and 2 is an acrylic plate (transparent light guide member). Reference numeral 3 denotes a reflector, 4 denotes a reflection sheet, 5 denotes a reflection tape, 6 denotes diffusion printing provided on the back surface of the acrylic plate 2, 7 denotes a dimming filter (a dimming member), and 8 denotes an adjustment knob (rotating part). ), 9 is a diffusion sheet, 10 is a backlight (light source device), 11 is a backlight case (light source case),
Reference numeral 12 denotes a liquid crystal display panel (display unit). As shown in FIG. 2, the edge-light type backlight unit is configured to freely rotate a cylindrical light-reducing filter 7 as a light-reducing member so as to cover the periphery of a cylindrical, straight tube-shaped fluorescent tube 1. And a flange-shaped adjusting knob 8 as a rotating part is provided around one end side of the cylindrical neutral density filter 7.

That is, the neutral density filter 7 has a cylindrical shape in which the dimming rate (density) is continuously varied in the circumferential direction, and is provided around one end of the cylindrical neutral density filter 7. A flange-shaped adjustment knob 8 is disposed outside the acrylic plate 7. Further, as shown in FIG. 1, a diffusion sheet 9 is provided on the front side of the acrylic plate 2 to constitute a backlight 10 as a light source device. The backlight 10 is housed in a backlight case 11 as a light source case. In addition, it is arranged on the back side of the liquid crystal display panel 12 as a display unit. Then, the adjusting knob 8 provided on the neutral density filter 7 is exposed from the backlight case 11 to the outside as shown in FIGS.

As described above, the cylindrical dimming filter 7 having the dimming rate (density) continuously changed in the circumferential direction so as to cover the periphery of the straight fluorescent tube 1. Since the adjusting knob 8 provided on the neutral density filter 7 is exposed to the outside from the backlight case 11, the adjusting knob 8 is operated to rotate the neutral density filter 7 so that the fluorescence can be reduced. The extinction ratio for the light emitted from the tube 1 can be changed continuously. That is, since the cylindrical light-attenuating filter 7 that covers the straight tube-shaped fluorescent tube 1 has a continuously different dimming rate (density) in the circumferential direction, the side end surface of the acrylic plate 2 is separated from the fluorescent tube 1. Light directly incident on the fluorescent tube 1
The light passes through the portion of the light reduction filter 7 located between the light reduction filter 7 and the acrylic plate 2, and is incident on the acrylic plate 2 by an amount of light corresponding to the light reduction rate (density) of the light reduction filter 7 portion.

Therefore, by operating the adjusting knob 8 to rotate the neutral density filter 7, the neutral density of the neutral density filter 7 located between the fluorescent tube 1 and the acrylic plate 2 is continuously reduced. Therefore, the extinction ratio with respect to the light emitted from the fluorescent tube 1 can be continuously changed by freely selecting the extinction ratio. As a result, the illumination light as the edge light type backlight 10 for the liquid crystal display panel 12 can be freely adjusted. In addition, an advantage that the electric circuit does not need to be changed can be obtained.

<Modification> In the above embodiment, the cylindrical light-attenuating filter 7 has the light-attenuating rate (density) continuously varied in the circumferential direction. The gradation of the extinction rate (density) is applied to the cylindrical extinction filter 7 so that stepwise extinction can be obtained.
However, the extinction ratio with respect to the light emitted from the fluorescent tube 1 can be continuously changed.

In the above-described embodiment, the illumination light adjusting structure for the backlight of the liquid crystal display device is used. However, the present invention is not limited to this, and the illumination light used for other display units is not limited to this. An adjusting structure may be used. In the embodiment, the backlight is of the edge light type. However, the present invention is not limited to the edge light type, and the present invention is applicable to a light source device including another backlight. In the embodiment, the rotating portion provided on the dimming member is manually operated. However, the power from a driving source such as a motor is transmitted to the rotating portion provided on the dimming member to automatically perform the operation. You may make it rotate. Further, it goes without saying that other specific detailed structures can be appropriately changed.

[0018]

As described above, according to the illumination light control structure for a display unit according to the first aspect of the present invention, the periphery of the cylindrical light source unit is covered and the light is continuously reduced in the circumferential direction. It has a cylindrical dimming member with different ratios, and has a rotating portion for rotating the dimming member. Therefore, if the dimming member is rotated by the rotating portion, the light source unit is moved from the light source unit to the display unit. The light emitted toward the back surface passes through the dimming member, and the dimming rate can be continuously changed. Therefore, it is possible to freely adjust the illumination light for the display unit, and it is possible to obtain an advantage that there is no need to change an electric circuit.

According to the display device of the second aspect of the present invention, since the illumination light adjusting structure of the display unit according to the first aspect is used, the illumination light adjusting structure of the display unit according to the first aspect of the invention is used. The effect obtained by can be exhibited.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a display unit and a backlight as an example to which the present invention is applied.

FIG. 2 is an exploded perspective view showing components of the backlight of FIG.

FIG. 3 is a partially cutaway side view showing a configuration of a dimming member and a rotating portion of the backlight in FIG. 1;

FIG. 4 is a plan view of a portion including a dimming member and a rotating portion of the backlight of FIG. 3;

FIG. 5 is an exploded perspective view showing an example of a conventional edge light type backlight unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Reflector 3 Light guide member 4 Reflection sheet 5 Reflection tape 6 Diffusion printing 7 Light reduction member 8 Rotating part 9 Diffusion sheet 10 Light source device 11 Light source case 12 Display part

Claims (2)

[Claims] 1. A cylindrical light source unit for illuminating a display unit from the back side, and a cylindrical shape covering the circumference of the light source unit, and the dimming rates are continuously different in the circumferential direction. An illumination light adjusting structure for a display unit, comprising: a light-reducing member; and a rotating part for rotating the light-reducing member. 2. A display device comprising the illumination light control structure for a display unit according to claim 1.