KR20070018676A - Backlight device - Google Patents

Abstract

In recent years, the size of liquid crystal television screens and the like is remarkable, and the direct type which arranges a plurality of cold-cathode discharge tubes on the back surface of a display is required, but the direct type not only deepens the depth from front to back, but also reduces the number. If it does not increase, it will be easy to produce a luminance unevenness, and therefore raises a problem of cost increase and enlargement.

According to the present invention, a barrier 3 is provided between each cold cathode discharge tube 2 to form a compartment 4, and at the same time, a light leakage means from an adjacent compartment is formed in a darkened portion in the compartment 4. By using the backlight 1 for supplying light by using the reflecting means, it is possible to simultaneously reduce the thickness and reduce the number, and further improve the display quality, thereby solving the problem.

Description

Backlight device {BACKLIGHT DEVICE}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross sectional view showing first light amount uniforming means in a backlight device according to the present invention;

Fig. 2 is a backlight showing an example of light distribution characteristics when the compartments for storing each cold cathode discharge tube are independent.

3 is a graph showing the luminous intensity of light leaking into adjacent sections at intervals between the apex of the partition wall between the partitions and the diffuser plate as light leakage from a section in contact with the left side;

4 is a graph showing the luminous intensity of light leaking into adjacent sections at intervals between the apex of the partition wall between the partitions and the diffuser plate as light leakage from a section in contact with the right side;

5 is a graph showing the shape of illumination light obtained by the first light amount uniforming means.

Fig. 6 is a schematic cross-sectional view showing second light amount equalization means in the backlight device according to the present invention.

7 is a graph showing an example of light distribution characteristics by the second light amount uniforming means.

Fig. 8 is a graph showing light distribution characteristics in the backlight device according to the present invention, in which the first light amount uniforming means and the second light amount uniforming means are added.

9 is a sectional view showing a conventional example.

<Explanation of symbols for main parts of drawing>

1: backlight device 1a: reflector

2, 2C, 2L, 2R: cold cathode discharge tube 3: barrier

3a: vertex 3b: bottom

3c: side 4: compartment

5: Diffusion plate D: gap between barrier and diffusion plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of a light source for backlight, which is used as a backlight device of a relatively large liquid crystal display such as a liquid crystal television, and is arranged by arranging a plurality of cold cathode discharges in parallel with a box-shaped case.

9 shows an example of the configuration of a conventional backlight device 90 (backlight light source) of this type. For example, a reflecting plate 91a in which white coating or the like is applied inside to improve reflectance is shown. A box-shaped member 91 is formed, and a plurality of cold cathode discharge tubes 92 are mounted therein at predetermined intervals, and in this example, the box-shaped portion 91 is spaced between the outer shell member 91b. It has a double structure, and the groove hole 91c is provided in the lower side where the said cold cathode discharge tube 92 was mounted.

A diffuser plate 93 is attached to an opening above the box-shaped member 91, and illuminates a liquid crystal display (not shown) provided above the diffuser plate 93 with transmitted light. (照明) Further, silicon grease 94 and the like having good thermal conductivity are injected into the lower groove hole 91c on which the cold cathode discharge tube 92 is mounted, and radiated to the outer member 91b in contact with the outside air. Is doing.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-196326

However, in the configuration of the above-described conventional backlight device 90, in order to make the entire surface of the display surface, that is, the entire surface of the diffusion plate 93 with uniform brightness, the interval between the cold cathode discharge tubes 92 is adjusted. It should be narrowed down so that a dark portion does not occur in the middle, and if the number of cold cathode discharge tubes 92 is increased in this way, even if the cold cathode discharge tubes 92 are not inclined to rise in temperature, the luminous efficiency is lowered. It is occurring.

Therefore, in reality, the depth of the box-shaped member 91 is deepened, the distance between the cold cathode discharge tubes 92 is appropriately widened, and at the same time, the back surface of the diffuser plate 93 is provided for the light spots that are still generated. In the upper portion of the negative electrode discharge tube 92, which tends to become bright, dot printing 95 is performed by using an opaque color such as black to adjust transmittance and the like, thereby obtaining a uniform brightness display. However, in order to suppress cost and power consumption, it is necessary to widen the intervals of the linear light sources, and thus, another means for eliminating light spots is required.

Therefore, in the backlight device 90 in the present state, the display quality is reduced by the display of insufficient brightness due to the decrease in the number of cold cathode discharge tubes 92, and the backlight device is made by the deep box-shaped member 91. (90) Problems such as the enlargement of the entire body, the injection of the silicon grease 94, the increase in the cost due to the increase in the number of processing steps such as the dot printing 95, and the like have arisen, and these problems have been solved. .

The present invention provides a specific means for solving the above-described conventional problems, comprising: a plurality of linear light sources arranged in parallel and having a diffuser plate for diffusing and transmitting light on the front side of the linear light source; At the same time, a backlight device having a diffuser plate for reflecting light in the diffuser plate direction on the back surface side of the linear light source, wherein the reflector is provided with a barrier between the linear light sources to provide the respective linear light sources. By forming a section for each time and adjusting the height of the barrier, the direct light from the adjacent linear light source is incident to the neighboring section, and the portion where the light lacks from the linear light source provided in the partition is adjacent to each other. Complemented by the incident light from the compartments, and uniformed the luminance of the illumination from the diffuser plate By providing values, it allows for the miniaturization and improvement of display quality, such as reduced cost and solve the problems.

[Embodiment of the Invention]

Next, this invention is demonstrated in detail based on embodiment shown in drawing. 1 denotes a backlight device according to the present invention (hereinafter referred to as a backlight 1), which basically includes titanium oxide, polycarbonate, PET, The reflecting plate 1a which is a housing body is formed by resin materials, such as ABS and a cycloolefin polymer, and the some cold cathode discharge tube 2 is mounted in predetermined space at predetermined intervals inside.

In addition, although this reflecting plate 1a is demonstrated as an example formed with the white resin material in this embodiment, you may be a metal member and resin member which colored the inner surface white. In addition, as an example of a linear light source, although demonstrated in the example of a cold cathode discharge tube, it is also possible to use what is called a fluorescent lamp, such as a hot cathode discharge tube.

In the middle where the cold cathode discharge tube 2 of each of the backlights 1 is mounted, a barrier 3 protruding from the cold cathode discharge tube 2 side is provided, whereby a compartment 4 is formed. . 1, one cold cathode discharge tube 2 is attached to one compartment. The diffusion plate 5 is provided on the upper surface of the backlight 1, and a liquid crystal display (not shown) is provided above, which is the same as the conventional example.

Now, here, an example of the illuminance distribution A1 of the cold cathode discharge tube 2 unitary body in one compartment 4 when the barrier 3 reaches the diffusion plate 5 is present. 2 is, of course, immediately above the cold cathode discharge tube 2, and darkens gradually toward the end of the compartment 4. And the ratio of the contrast is about 2.5 times, for example, it is not a value which can appreciate the television image.

In the present invention, as a first means for uniformizing the contrast, the height of the barrier 3 is adjusted, and the light from the cold cathode discharge tube 2 is also distributed to the neighboring sections 4. This will be described with reference to FIG. 1. Since three cold cathode discharge tubes 2 are shown in FIG. 1, first, the cold cathode discharge tube on the left side is 2L, and the cold cathode discharge tube on the right side is shown. It is assumed that it is 2R and the cold cathode discharge tube in the center is 2C.

Here, first, if the height of the barrier 3 reaches the diffuser plate 5, each of the compartments 4 is an optically independent configuration close to the four sides, from the cold cathode discharge tube (2L, 2R) Does not enter the center section, ie, the section 4 provided with the cold cathode discharge tube 2C, and does not affect each. FIG. 2 shows the state of light distribution H1 of each compartment 4 in this state.

As is apparent from FIG. 2, in the light distribution H1 in the state where each compartment 4 is independent as described above, the portion immediately above the cold cathode discharge tube 2 is the brightest and the end of the compartment 4. Brightness decreases gradually, and the contrast at that time is about 2.5 times. In this embodiment, the distance between each cold cathode discharge tube 2 is set to 40 mm. Moreover, the distance between the reflecting surface side lowest point of the reflecting plate 1a and the linear light source side of the linear light source diffuser plate 5 of the diffuser plate 5 is about 18 mm, and the distance between the linear light sources is It is wide.

In the present invention, first, as the first means, by adjusting the height of the barrier 3, a gap D is provided between the barrier 3 and the diffusion plate 5 (see FIG. 1), and this interval D By adjusting the amount of), light from the cold cathode discharge tube 2 located next to the light is introduced into a portion where the amount of light is insufficient, so that uniform brightness is realized in one compartment 4.

Here, referring to FIG. 2 again, as described above, in one compartment 4, the light distribution H1 shows the light quantity value of the light collection just above the cold cathode discharge tube 2. The so-called center has a shape in which the amount of light decreases as it moves in the direction. Therefore, in reality, it is not necessary to distribute the light from the adjacent sections 4 immediately above the cold cathode discharge tube 2, and it is sufficient to reinforce the portion where the amount of light at the left and right ends decreases.

Therefore, in the present invention, the light quantity of the compartment 4 to be supplied is, in principle, to be able to supply a large amount of light from the compartment 4 in contact with the left side to a right side, in principle. The mountain shape shown in FIG. 2 is compensated and faces toward the direction to be uniform.

In order to receive light supply from adjacent sections as described above, for example, the width and position of the space D placed at the boundary with the section 4 on the left side are adjusted to adjust the width and position of the section 4 on the side to which the light is supplied. What is necessary is not to let light reach a right half part rather than the center of (circle), and similarly, the space | interval D placed in the boundary with the compartment 4 which contact | connects the right side may make it not let light reach a left half part.

At this time, in the vicinity of the center of the side to which the light is supplied, the cold cathode discharge tube 2 has a predetermined pipe diameter and reflects different ranges blocked by the tip of the barrier 3. The portion S is generated and is smaller than the amount of light irradiated by the entire tube diameter of the cold cathode discharge tube 2. As the reflecting portion S moves away from the cold cathode discharge tube 2, the range of the cold cathode tube being blocked by the barrier 3 increases, so that the amount of light gradually decreases.

As described above, since the central portion of the compartment 4 is a portion in which a sufficient amount of light is distributed, even if the reflecting portion S may overlap with the central portion, it may cause a problem in practical use. Although no influence occurs, it is preferable that portions other than the reflecting portion S do not overlap with the central portion.

FIG. 3 shows an example of one of the shapes of the light distribution HL incident from the compartment 4 on the left side when the gap D is formed as described above, and FIG. 4 shows the right side formed in the same manner. An example of light distribution HR incident from the partition 4 of Fig. 4 is shown. 5 illustrates light distribution H2 obtained by adding the light distribution HL and the light distribution HR to the light distribution H1 of FIG. 2.

Here, when comparing the light distribution H1 and the light distribution H2, there is no difference that the shape of the center is high with both the amount of light at the center of both, but in more detail, the light distribution H1 has a maximum value and a minimum value of the light amount. While the difference of was about 2.5, it can be seen that in the light distribution H2, the effect corresponding to the uniformity of brightness was shown at about 1.5 times.

In this invention, in addition to the 1st homogenization means demonstrated above, the 2nd homogenization means was combined and the said barrier 3 is also used for this 2nd homogenization means. That is, in the 1st homogenization means, it performed by reinforcing to the part which lacks the light from the partition 4 to adjoin by the space | interval D of the barrier 3 and the diffuser plate 5.

Referring to the operation of the barrier 3 according to FIG. 1, the barrier 3 requires an interval D for securing the amount of light supplied to an adjacent section, that is, a vertex 3a. Only the position where) is present is required, and the side surface 3c for connecting and holding the apex 3a to the bottom surface 3b is substantially particularly effective when a reflecting plate made of a white resin is used. Not expected

In view of this point, the present invention intends to realize more uniformity using the side surface 3c as well, and also in the light distribution H2 provided with the first equalization means shown in FIG. There is still a tendency for the center part of the compartment 4 to be bright, and it cannot be said that it has sufficient performance as a complete backlight 1.

Therefore, in the present invention, as shown in Fig. 6, the side surface 3c of the barrier 3 has the cold cathode discharge tube 2 or its vicinity as the first focal point, and the apex of the barrier 3 It is formed as a shape of a part of an ellipse shape which makes the vicinity of the diffuser plate 5 of 3 a) just above a 2nd focal point, ie, an ellipse surface has the long axis Z formed in the said cold cathode discharge tube ( As a state to be moved parallel to the axis of 2), it reaches a necessary portion, that is, from the vertex 3a of the barrier 3 to the bottom surface 3b which is a flat surface, and is formed in strip shape.

Moreover, although the position of the 2nd focal point of the said ellipsoid is made into the vicinity of the diffuser plate 5 in the direction immediately above the vertex 3a of the said barrier 3, this is a light irradiation by moving this position somewhat up and down, right and left Since adjustment of a characteristic and a range is possible, it means to include this also in this invention.

In addition, since the barrier 3 exists on both sides of the cold cathode discharge tube 2, the barrier 3 is formed on both sides, and since the partition 4 is adjacent to each other in close contact, the barrier 3 has a front and back. The ellipsoid is formed in a table. In the present embodiment, since the reflecting plate 1a is formed of a white resin and includes many functions of diffusing to the light from the linear light source, the concentration of light to the focus is reduced. When the positive reflection component of the reflecting plate 1a is made high, such as polishing a metal mold for forming the reflecting plate 1a, the light to the focus can be increased. Moreover, when using the metal member and resin member which the reflecting plate was colored in the inner surface etc., what is necessary is just to coat with a fine white paint etc., for example.

FIG. 7 shows the state of the light distribution H0 in one compartment 4 provided with the barrier 3 having the ellipsoidal side surface 3c formed as described above. The maximum amount of light is obtained at the position of the barrier 3. 8 is the final light distribution H3 combined with the division 4 provided with the 1st equalization means shown in FIG.

At this time, the vertex 3a can adjust the height position by the shape of the ellipse (focal length) and the inclination of the long axis Z, and the position of the reflecting portion S is adjacent by the adjustment of the height. Make sure it is just above the light source. Moreover, the elliptical side surface 3c and the flat surface 3b are connected by a suitable curve, and it is good not to generate | occur | produce a luminance unevenness by this boundary.

By combining the two kinds of equalization means in this manner, the light quantity difference is within the range that can be said to be substantially uniform at about 11 at the center of the compartment 4 and about 10 at the end of the compartment, as shown in the figure. It became possible to endure practically enough. In addition, in the case where correction by the elliptic surface is too good or the like, a part of the side surface 3c of the barrier 3 is formed in the ellipsoidal surface, and the other part is freely formed.

As described above, according to the present invention, the first method of distributing the light from the adjacent sections 4 to the insufficient portions, and the side surface 3c of the barrier 3 are formed in an elliptical surface to provide a second focus on the required portion. By combining the second method of setting and intensively distributing the light to form the backlight 1, first, a uniform amount of light is obtained on the entire surface, thereby enabling the performance of the backlight 1 to be improved.

Secondly, with the above configuration, it is possible to form the backlight 1 capable of maintaining the uniformity of brightness even if the distance between the cold cathode discharge tubes 2 is farther than conventionally. In addition, the uniformity is achieved. In this case, the backlight 1 can be implemented in a state where the thickness of the backlight 1 is thin, which makes it possible to reduce the size of the entire liquid crystal display, thereby enabling cost reduction.

According to the present invention, for example, a liquid crystal television or a computer display can be further miniaturized and the display quality can be improved, thereby improving both practicality and performance. It generates the advantage of facilitating dissemination. That is, if the number of linear light sources is the same as the conventional one, the thickness of the backlight device can be made thin. On the contrary, if the thickness of the backlight device is the same, the equivalent function can be achieved with a smaller number of linear light sources than the conventional one.

Claims (5)

A plurality of linear light sources are arranged in parallel and provided with a diffuser plate for diffusing and transmitting the light on the front side of the linear light source, and a diffuser for reflecting light toward the diffuser plate on the back side of the linear light source. A backlight device provided with a plate, wherein the reflecting plate is provided with a barrier between each of the linear light sources to form a partition for each of the linear light sources, and the height of the barrier is adjusted to adjust the height of the adjacent line. The direct light from the shape light source is incident to a neighboring compartment, and the portion lacking the light from the linear light source provided in the compartment is compensated by the incident light from the neighboring compartment, and the irradiation luminance from the diffuser plate is uniformed. Backlight device. The method according to claim 1, The range of the direct light incident on the adjacent section includes a reflecting part in which part of the tube diameter of the linear light source is blocked by the barrier, and almost half of the side where the section is in contact ( A back light device characterized by the above-mentioned. The method according to claim 1 or 2, The partition wall has an elliptic curved surface having a first focus in the linear light source or its vicinity and having a second focus in the vicinity of the diffuser plate in the direction immediately above the apex of the partition wall, for light quantity distribution adjustment. Backlight device. The method according to any one of claims 1 to 3, And said reflecting plate of said backlight device is formed of a member having an appropriate diffusivity and an appropriate reflectivity. The method according to claim 4, The reflecting plate is formed of a white resin material.

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