JP2009271144A - Backlight and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight for effectively suppressing brightness irregularity while achieving reduction of power consumption, and to provide a liquid crystal display using the same. <P>SOLUTION: In the backlight 10 for dividing an arrangement region arranging light emitting elements 12 into a plurality of division regions A1, A2 and driving the light emitting element 12 in each division region A1, A2, each of a plurality of the light emitting elements 12 arranged along the boundary X of the division region 12 is connected to any one of a drive circuit of the division region A1 to which the light emitting element 12 belongs and a drive circuit of the adjacent division region A2, and the boundary Y of light emitting regions B1, B2 formed with the light emitting element 12 connected to the same drive circuit makes non-linearity such as substantially rectangular wave shape or substantially triangular shape. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

   The present invention relates to a backlight in which an array region in which light emitting elements are arrayed is divided into a plurality of divided regions, and the light emitting elements are driven in each divided region, and a transmissive liquid crystal display device employing the backlight.

  Conventionally, a liquid crystal display device that displays an image using a liquid crystal display element is known. The types of liquid crystal display elements include a reflective liquid crystal display element that adjusts the amount of reflected light according to an image signal, and a transmissive type that adjusts the amount of transmitted light according to an image signal. There is a liquid crystal display element.

  In recent years, liquid crystal display devices using such liquid crystal display elements have been adopted in various devices such as information devices such as computers, television receivers, and the like. Here, in a liquid crystal display device using a transmissive liquid crystal display element, the liquid crystal display element is irradiated with illumination light, and the illumination light is modulated by the liquid crystal display element according to an image signal and selectively transmitted. As a result, an image is displayed. As an illumination method for the liquid crystal display element, a backlight that emits illumination light from the back surface of the liquid crystal display element is often used.

Conventionally, in such a liquid crystal display device using a backlight, for example, even when an image is displayed only on a part of the screen, the entire screen is illuminated, so that the power consumption is more than necessary. It was getting bigger.
Therefore, for example, Patent Document 1 discloses a liquid crystal display device in which a light emitting element that emits illumination light for irradiating a liquid crystal panel (liquid crystal display element) is arranged for each of a plurality of divided areas, and the light emitting elements are driven and controlled in units of divided areas. Is disclosed.
Accordingly, it is possible to prevent illumination light from being irradiated to a screen area that does not need to be illuminated, and thus it is possible to reduce power consumption.
In addition, those described in Patent Document 2 and Patent Document 3 are known as liquid crystal display devices that drive light emitting elements for each divided region.
JP 2001-142409 A JP 2005-258403 A JP 2008-010397 A

However, the liquid crystal display device as described above has the following problems.
That is, in the case of a method in which a light emitting element is arranged for each of a plurality of divided regions and driven in units of the divided regions, the divided region units are often formed in a quadrangular shape mainly due to manufacturing convenience. For this reason, the boundary of the divided area is divided linearly. In such a liquid crystal display device in units of divided areas, if the light emitting elements in all the divided areas are simultaneously driven to illuminate the entire screen, it is difficult to completely match the luminance and color tone of each divided area. There is a problem in that the image quality is deteriorated by perceiving a luminance difference or a color tone difference at the boundary of the divided areas in the image. This is because, due to human visual characteristics, when there is a minute luminance difference between adjacent areas, the boundary line (luminance difference) is easily perceived when the boundary line has a clear shape such as a straight line.
In addition, in order to correct such luminance unevenness and color unevenness, it is conceivable to perform drive control for each light emitting element to obtain a desired luminance distribution and color tone, but the drive circuit becomes complicated and adjustment takes time. Since it takes too much, it is not preferable.

  The present invention has been made in view of such problems, and in a backlight in which a light emitting element is arranged for each of a plurality of divided areas and driven in units of the divided areas, luminance unevenness and color generated at the boundaries of the divided areas. It is an object of the present invention to provide a backlight capable of effectively suppressing unevenness and a liquid crystal display device that achieves high image quality by using the backlight.

In order to solve the above problems, the present invention proposes the following means.
That is, in the backlight according to the present invention, the array area in which the light emitting elements are arrayed is divided into a plurality of divided areas, and the boundary between the divided areas in the backlight in which the light emitting elements are driven for each of the divided areas. A part of at least one row of the light emitting elements arranged along the line is connected to a drive circuit of another divided region adjacent to the divided region to which the light emitting element belongs via the boundary. It is said.

  According to the backlight having such a feature, a part of the light emitting elements along the boundary of the divided areas is driven together with the light emitting elements of the adjacent divided areas, so that the shape of the boundary line of the adjacent divided areas is It becomes complicated and it becomes difficult to perceive the luminance difference and the color tone difference at the boundary line. That is, the luminance difference and color tone difference before and after the boundary line can be visually averaged. This makes it possible to reduce luminance unevenness and color unevenness between the divided regions.

  Further, in the backlight according to the present invention, each of the at least one row of the light emitting elements arranged along the boundary of the divided area includes a driving circuit for the divided area to which the light emitting element belongs and driving of the other divided area. The boundary between the light emitting regions formed by the light emitting elements connected to any one of the circuits and connected to the same drive circuit has a substantially rectangular wave shape or a substantially triangular wave shape.

  According to the backlight having such a feature, the boundary between the light emitting regions becomes an intricate shape such as a substantially rectangular wave shape or a substantially triangular shape. It is possible to reduce the luminance difference and the color tone difference in terms of visual characteristics.

  Furthermore, in the backlight according to the present invention, each of the at least one row of the light emitting elements arranged along the boundary of the divided area includes a driving circuit for the divided area to which the light emitting element belongs and driving of the other divided area. A boundary between light emitting regions formed by the light emitting elements connected to any one of the circuits and connected to the same drive circuit is formed in a non-linear shape.

  The boundary between the issue areas is non-linear, that is, it becomes difficult to perceive minute brightness differences and color differences before and after the boundary line by forming a complicated shape such as a broken line shape or uneven shape other than a simple straight line. In addition, the luminance difference and the color tone difference can be reduced in terms of visual characteristics.

  In the backlight, the light emitting element is preferably a light emitting diode. As a result, it is possible to achieve high luminance, low power consumption, and long life of the light emitting element.

A liquid crystal display device according to the present invention includes any one of the backlights described above, and a liquid crystal display element that receives light from the backlight from the back side and displays an image.
By adopting the backlight in a liquid crystal display device, it becomes difficult to perceive a luminance difference and a color tone difference at the boundary of the divided areas of the backlight, so that high image quality can be achieved.

According to the backlight of the present invention, the luminance difference and the color tone difference at the boundary between the divided areas are averaged by driving the light emitting elements arranged along the boundary between the divided areas together with the light emitting elements of the adjacent divided areas. Thus, it is possible to effectively suppress the occurrence of luminance unevenness and color unevenness.
In addition, according to the liquid crystal display device of the present invention, it is possible to improve the image quality by adopting the backlight.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a liquid crystal display device according to this embodiment, and FIG. 2 is a schematic configuration diagram of a backlight according to this embodiment.
The liquid crystal display device 1 of the present embodiment includes a transmissive liquid crystal display element 2 that adjusts the amount of transmitted light according to an image signal, and illuminates the liquid crystal display device 2 on the back side thereof. A backlight 10 for irradiating light is provided.

As shown in FIG. 2, in the backlight 10, a plurality of light emitting elements 12 are arranged in a lattice shape (vertical 20 × horizontal 38) on the upper surface of the base substrate 11 to form an array region. This array area is divided into a plurality of divided areas, for example, a total of 32 divided areas A, A,... Thus, in the backlight 10, 5 vertical elements × 4 horizontal elements are arranged in the divided areas A located at the left and right ends of FIG. 2, and 5 vertical elements × 5 horizontal elements are arranged in the other divided areas A. Will be.
Note that the numbers of the light emitting elements 12 and the divided regions A are not limited to the above, and can be appropriately changed according to the size and configuration of the liquid crystal display device 1. Moreover, in this embodiment, although LED, especially white LED is used as the light emitting element 12, it is not limited to this, You may use LED of RGB or RGBW.

  In FIG. 2, a drive circuit 21 drives a plurality of light emitting elements 12 arranged in each divided area A, and light emitting elements in each divided area A based on a drive signal from the control circuit 20. Each of the twelve emission intensities can be controlled. The drive circuits 21 are provided in the same number as that of the divided areas A. Accordingly, in the backlight 10 of the present embodiment, the light emitting elements 12 are driven independently for each divided area A.

  In this embodiment, a part of the light emitting elements 12 arranged along the boundary X of the divided area A is connected to the drive circuit 21 in another divided area A adjacent to the boundary X. . Hereinafter, a specific example thereof will be described with reference to FIGS.

FIG. 3 is a view in the vicinity of the boundary X between two adjacent divided regions A1 and A2 showing the first specific example.
In FIG. 3, the vertical row of light emitting elements 12 in the divided area A1 arranged along the boundary X extending in the vertical direction are alternately connected to the drive circuit 21 in the divided area A1 and the drive circuit 21 in the divided area A2. ing.
That is, in principle, the light emitting elements 12 arranged in the divided areas A1 and A2 are connected to the drive circuits 21 corresponding to the divided areas A1 and A2 to which the light emitting elements 12 belong, respectively. Only a part of the light emitting elements 12 in one row is connected to the drive circuit 21 corresponding to the adjacent divided region A2.

  Thus, the light emitting region B1 formed by the light emitting element 12 connected to the drive circuit 21 corresponding to the divided region A1, and the light emitting region formed by the light emitting element 12 connected to the drive circuit 21 corresponding to the divided region A2. The boundary Y with B2 is formed in a substantially rectangular wave shape as shown in FIG.

FIG. 4 is a view in the vicinity of the boundary X between two adjacent divided regions A1 and A2 showing the specific example 2.
In FIG. 4, the light emitting elements 12 in two columns arranged with the boundary X in between are alternately connected to the drive circuit 21 corresponding to the divided area A1 and the drive circuit 21 corresponding to the divided area A2. Yes. Also in this manner, as in the first specific example, the boundary Y between the light emitting region B1 and the light emitting region B2 is formed to have a substantially rectangular wave shape.

FIG. 5 is a view in the vicinity of a boundary X between four adjacent divided regions A1, A2, A3, and A4 showing the specific example 3.
In FIG. 5, two vertical rows of light emitting elements 12 arranged with a vertically extending boundary X therebetween are a drive circuit 21 corresponding to the divided regions A1 and A3 and a drive circuit 21 corresponding to the divided regions A2 and A4. It is connected to either one. Thus, the light emitting region B1 formed by the light emitting element 12 connected to the drive circuit corresponding to the divided regions A1 and A3 and the light emitting element 12 connected to the drive circuit 21 corresponding to the divided regions A2 and A4 are formed. The boundary Y with the light emitting region B2 has a substantially triangular wave shape as shown in FIG.

FIG. 6 is a diagram in the vicinity of a boundary X between four adjacent divided regions A1, A2, A3, and A4 showing the specific example 4.
In FIG. 6, four vertical rows of light emitting elements 12 arranged across a vertically extending boundary X include a drive circuit 21 corresponding to divided areas A1 and A3 and a drive circuit 21 corresponding to divided areas A2 and A4. It is connected to either one. Thereby, the boundary Y between the light emitting region B1 and the light emitting region B2 has a substantially triangular wave shape as shown in FIG.

Next, the operation of the backlight 10 and the liquid crystal display device 1 configured as described above will be described.
When an image is displayed on the liquid crystal display device 1, the control circuit 20 of the backlight 10 drives the light emitting elements 12 in the respective divided regions A, A. Thus, when the backlight 10 is turned on and the liquid crystal display element 2 is illuminated from the back, the liquid crystal display element 2 adjusts the amount of transmitted light according to a given image signal, thereby displaying an image on the display screen. Is displayed.

At this time, in the backlight 10 of the present embodiment, since the light emitting element 12 is driven for each divided region A, when an image is displayed only on a part of the display screen, the part corresponds to the part. Only the light emitting element 12 in the divided area A needs to be driven. Accordingly, since it is possible to prevent illumination light from being irradiated to a screen area where it is not necessary to display an image, it is possible to reduce power consumption. Further, an LED is used as the light emitting element 12. Therefore, it is possible to increase the luminance and life of the light emitting element and further reduce power consumption.

And in the backlight 10 of this embodiment, as shown in the said specific examples 1 to 4, the light emitting element 12 near the boundary X of each divided area A, A ... is the divided area A to which the light emitting element 12 belongs. Since the boundary Y between the light emitting regions B1 and B2 is formed in a substantially rectangular shape or a substantially triangular shape by being connected to either the drive circuit 21 or the drive circuit 21 of the adjacent divided region A, the divided region A The luminance difference and the color tone difference at the boundary X are not easily perceived.
That is, since the boundary X of the divided area A is linear, the boundary Y of the light emitting areas B1 and B2 is intricately shaped. Even when the color tone is slightly different, the luminance difference and the color tone difference are hardly perceived near the boundary X, and as a result, the luminance difference and the color tone difference between the divided areas A can be reduced in terms of visual characteristics.

  In addition, in the liquid crystal display device 1 configured to irradiate the liquid crystal display element 2 with such a backlight 10, luminance unevenness and color unevenness do not occur in a portion corresponding to the boundary X of the divided region A. It is possible to display an image with high image quality.

The backlight 10 and the liquid crystal display device 1 according to the present invention have been described in detail above. However, the present invention is not limited to these without departing from the technical idea of the present invention, and some design changes and the like are possible. .
For example, in the present embodiment, the light emitting elements 12 are arranged in a grid pattern, but the present invention is not limited to this. For example, a honeycomb arrangement or a delta arrangement may be used.
Further, as long as a part of the light emitting elements 12 arranged along the boundary X of the divided area A is connected to the drive circuit 21 of another adjacent divided area A, the boundary Y of the light emitting areas B1 and B2 is rectangular. The shape is not limited to a wave shape or a triangular wave shape, and may be a shape other than a straight line.

It is a perspective view of the liquid crystal display device concerning this embodiment. It is a schematic block diagram of the backlight which concerns on this embodiment. It is a figure explaining the aspect of the boundary of the light emission area | region of the specific example 1. FIG. It is a figure explaining the aspect of the boundary of the light emission area | region of the specific example 2. FIG. It is a figure explaining the aspect of the boundary of the light emission area | region of the specific example 3. FIG. It is a figure explaining the aspect of the boundary of the light emission area | region of the specific example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 10 Backlight 12 Light emitting element 21 Drive circuit A, A1, A2, A3, A4 Division | segmentation area | region B1, B2 Light emission area | region
X Boundary of divided area Y Boundary of light emitting area

Claims (5)

In the backlight in which the array region in which the light emitting elements are arranged is divided into a plurality of divided regions, and the light emitting elements are driven for each of the divided regions,
A part of at least one row of the light emitting elements arranged along a boundary of the divided region is
A backlight characterized in that the backlight is connected to a drive circuit of another divided region adjacent to the divided region to which the light emitting element belongs via the boundary. Each of the at least one column of the light emitting elements arranged along the boundary of the divided area is connected to either the driving circuit of the divided area to which the light emitting element belongs or the driving circuit of the other divided area,
2. The backlight according to claim 1, wherein a boundary between light emitting regions formed by the light emitting elements connected to the same drive circuit has a substantially rectangular wave shape or a substantially triangular wave shape. Each of the at least one column of the light emitting elements arranged along the boundary of the divided area is connected to either the driving circuit of the divided area to which the light emitting element belongs or the driving circuit of the other divided area,
The backlight according to claim 1, wherein a boundary between light emitting regions formed by the light emitting elements connected to the same drive circuit is formed in a non-linear shape.   The backlight according to any one of claims 1 to 3, wherein the light emitting element is a light emitting diode. The backlight according to any one of claims 1 to 4,
A liquid crystal display device comprising: a liquid crystal display element that receives light from the backlight from the back side and displays an image.

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