JP2008292624A - Liquid crystal module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal module having a linear light source as a backlight light source, in which a leakage current due to a stray capacitance generated in the linear light source can be reduced at low cost. <P>SOLUTION: The liquid crystal module 50 includes a metallic rear frame 1 and a plurality of linear light sources 3a comprising cold cathode fluorescent lamps. To each of the plurality of linear light sources 3a, a strip-like planar insulating material 21 is stuck just under the light source over the entire region of the part of the linear light source 3a emitting light to illuminate the liquid crystal panel (not shown in the figure). The planar insulating material 21 is disposed as capable of reflecting the light emitting from the linear light source 3a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal module used as a display device of an electronic device such as a television receiver or a microcomputer, and more specifically, to a stray capacitance generated in a linear light source for a backlight provided in the liquid crystal module. The present invention relates to a configuration for reducing leakage current.

  Conventionally, liquid crystal modules have been used as display devices for electronic devices such as television receivers and microcomputers. FIG. 5 is an exploded perspective view showing a configuration of a conventional liquid crystal module. The configuration of the conventional liquid crystal module 100 will be described with reference to FIG. A conventional liquid crystal module 100 includes a rear frame 1, a reflection sheet 2, a backlight light source 3, a diffusion plate 4, an optical sheet 5, and a liquid crystal panel 6.

  The rear frame 1 is made of metal and has a structure capable of accommodating the reflection sheet 2 and the backlight light source 3. The reflection sheet 2 is formed of an insulating white synthetic resin plate and is placed on the rear frame 1. The reflection sheet 2 is provided to reflect light emitted from the backlight light source 3.

  The backlight light source 3 is formed by collecting a plurality of linear light sources 3a. In the conventional liquid crystal module 100 shown in FIG. 5, the number of linear light sources 3a is sixteen. The linear light source 3a is specifically composed of a cold cathode fluorescent lamp (CCFL), but in the liquid crystal module 100, two linear light sources 3a are paired to form one CCFL 3b. To do. That is, one end portions of the two linear light sources 3a are connected to each other to form one U-shaped CCFL 3b.

  The U-shaped CCFL 3b is supported at one end by a lamp holder 7 made of an elastic member such as silicon rubber. The other end is inserted into the lamp socket 8, and the CCFL 3b is connected to an inverter circuit (not shown) through the lamp socket 8. Such a U-shaped CCFL 3b is driven by applying alternating voltages to both ends of the CCFL 3b so as to be in opposite phases.

  Each of the linear light sources 3a constituting the backlight light source 3 is supported by a light source support member (not shown). This prevents the linear light source 3a from being bent by its own weight. That is, the distance between the linear light source 3a and the rear frame 1 is configured to be substantially constant at any position.

  The diffusing plate 4 has a function of diffusing the light directly emitted from the backlight light source 3 and the light incident after being reflected by the reflection sheet 2 after being emitted from the backlight light source 3. Further, the optical sheet 5 includes a diffusion sheet for diffusing light, and here, the incident light is diffused to correct luminance unevenness and the like. The diffusion plate 4 and the optical sheet 5 are pressed against the rear frame 1 by the cell guide 9.

  A liquid crystal panel 6 is disposed on the upper side of the optical sheet 5. The liquid crystal panel 6 has a known structure including a pair of polarizing filters, a pair of glass substrates provided between the polarizing filters, and a liquid crystal, a transparent electrode, a color filter, and the like provided between the glass substrates. Have. The position of the liquid crystal panel 6 is regulated by the cell guide 9 and is fixed by the bezel 10.

  In the liquid crystal module 100 configured as described above, the CCFL 3b constituting the backlight light source 3 tends to become longer due to the recent increase in size of the liquid crystal module. Further, the rear frame 1 constituting the liquid crystal module 100 is generally formed of metal in consideration of cost and the like. For this reason, the following problems occur.

  FIG. 6 is a schematic diagram for explaining problems in the conventional liquid crystal module 100. As shown in FIG. 6, in the conventional liquid crystal module 100, since the rear frame 1 is made of metal, stray capacitance is generated between the lamp tube of the linear light source 3a constituting the CCFL 3b and the rear frame 1. In this case, leakage occurs in the lamp current (tube current) flowing through the CCFL, resulting in leakage current. And since the length of the linear light source 3a tends to become longer due to the trend toward larger liquid crystal modules in recent years, the difference in effective tube current between the high pressure side and the low pressure side of the linear light source 3a increases. A phenomenon occurs. That is, when the length of the linear light source 3a is increased with the increase in size of the liquid crystal module, the linear light source 3a has a problem that a luminance gradient occurs such that the luminance is increased on the high voltage side and the luminance is decreased on the low voltage side. Become.

  By the way, the problem of leakage current based on stray capacitance has been conventionally known in the field of liquid crystal modules, for example, those disclosed in Patent Document 1 and Patent Document 2. In Patent Document 1, an increase in leakage current due to stray capacitance generated between a high-voltage side electrode and a low-voltage side electrode as the axial length of a cylindrical light source increases with an increase in the screen size of the backlight device. Pointing out the problem of luminance unevenness due to the above, a technique for reducing this luminance unevenness has been introduced. Specifically, a configuration in which a through hole that does not generate stray capacitance is provided at the bottom of the casing (corresponding to the bottom 1a of the rear frame 1 in FIG. 5) at least in the vicinity of the high voltage supply side of the backlight device. Has been. According to this, the distributed stray capacitance between the tube wall of the cylindrical light source and the bottom of the housing can be made uniform or reduced, and the leakage current can be reduced to reduce the luminance unevenness.

Japanese Patent Application Laid-Open No. 2004-228561 aims to reduce non-uniform luminance of the fluorescent tube caused by leakage current flowing through the fluorescent tube to the metal casing through the stray capacitance, and non-uniform luminance of the lighting device resulting therefrom. Technology is introduced. This patent document 2 suppresses the fluctuation of the stray capacitance due to the deflection of the fluorescent tube and the metal casing itself. By intentionally deflecting the fluorescent tube to the opposite side of the bottom of the metal casing by the fluorescent tube holder, Even if the tube or the metal casing is bent, the distance between the fluorescent tube and the metal casing is ensured to be a certain level or more. As a result, the stray capacitance is reduced and the leakage current can be reduced, so that nonuniform luminance due to the stray capacitance can be reduced.
JP 2004-220980 A JP 2006-172965 A

  However, if the leakage current (leakage current) is reduced by the configuration of Patent Document 1, the rear frame 1 needs to have a large number of through holes, so that the strength of the rear frame 1 is reduced, and the liquid crystal module. There may be a problem such as a decrease in strength.

  In addition, referring to Patent Document 2, it can be considered that the distance between the linear light source 3a and the rear frame 1 is separated by a certain distance or more to reduce the luminance gradient caused by the leakage current. The increase in the distance between the linear light source 3a and the rear frame 1 increases the thickness of the liquid crystal module, which is contrary to the tendency to reduce the thickness of the liquid crystal module.

  As a configuration for reducing the influence of leakage current by a method different from Patent Documents 1 and 2, the thickness of the reflective sheet 2 provided between the backlight light source 3 and the rear frame 1 is made thicker than the conventional configuration ( It is also conceivable that the number of reflection sheets 2 is increased. Since the reflection sheet 2 is made of an insulator, it is possible to reduce the leakage current by adopting such a structure. In the case of such a configuration, it is possible to reduce the leakage current based on the stray capacitance while avoiding the strength reduction and the thickness increase of the liquid crystal module. However, since the cost of the reflective sheet 2 is not necessarily low, it is not desirable to simply increase the thickness of the reflective sheet 2.

  In view of the above points, an object of the present invention is to provide a liquid crystal module that can reduce leakage current based on stray capacitance generated in a linear light source at a low cost in a liquid crystal module including a linear light source as a backlight light source. That is.

  In order to achieve the above object, the present invention provides a liquid crystal panel, a plurality of linear light sources arranged on the back side of the liquid crystal panel, and a side opposite to the side on which the liquid crystal panel is arranged based on the linear light source. A reflective sheet that reflects light emitted from the linear light source, and is disposed on a side opposite to the side on which the linear light source is disposed with respect to the reflective sheet, and the reflective sheet is placed thereon In a liquid crystal module comprising a metal frame, an insulator that reduces leakage current generated in a portion that emits light for illuminating the liquid crystal panel of the linear light source between the linear light source and the metal frame. , And is arranged separately from the reflection sheet.

  According to this configuration, the amount of the insulator disposed between the linear light source and the metal frame is increased by the insulator disposed between the linear light source and the metal frame as compared with the conventional case. . In the case of this configuration, it is possible to reduce the leakage current at a lower cost than in the case where the thickness of the reflection sheet conventionally provided in the liquid crystal module is simply increased to reduce the leakage current.

  In the liquid crystal module having the above-described configuration according to the present invention, it is preferable that the insulator is provided so as to be able to reflect light emitted from the linear light source and is attached to each of the plurality of linear light sources. . According to this configuration, even when the insulator used for reducing the leakage current is made of the same material as that of the reflection sheet, the leakage current can be reduced by reducing the amount of material used compared to the case of simply increasing the thickness of the reflection sheet. Can be reduced. That is, it is possible to reduce the leakage current generated in the linear light source at a low cost. In the case of this configuration, it is also possible to increase the reflected light rate of light emitted from the linear light source.

  In the liquid crystal module having the above-described configuration, the insulator may be provided in a plan view band shape along the longitudinal direction of the linear light source. According to this configuration, it is possible to easily realize a liquid crystal module that can reduce leakage current at low cost.

  In the liquid crystal module having the above-described configuration, the present invention may be provided such that the insulator is curved and surrounds a part of the linear light source. According to this configuration, it is possible to easily realize a liquid crystal module that can reduce the leakage current at low cost, and the reflected light of the light emitted from the linear light source by the insulator arranged to reduce the leakage current. The rate can be increased. Therefore, by attaching an insulator to the linear light source, it is possible to increase the utilization efficiency of light emitted from the linear light source in addition to the reduction of leakage current.

  In the liquid crystal module having the above configuration according to the present invention, it is preferable that the insulator is provided over the entire area of the linear light source that emits light for illuminating the liquid crystal panel. According to this configuration, it is possible to more effectively reduce the leakage current in the portion that emits light for illuminating the liquid crystal panel of the linear light source.

  According to the liquid crystal module of the present invention, leakage current based on stray capacitance generated in a linear light source provided as a light source for backlight can be reduced at low cost. For this reason, it is easy to provide a liquid crystal module that can reduce luminance unevenness.

  Hereinafter, embodiments of a liquid crystal module of the present invention will be described with reference to the drawings. In addition, embodiment shown here is an example and this invention is not limited to embodiment shown here.

(First embodiment)
FIG. 1 is a schematic plan view showing a part of the liquid crystal module according to the first embodiment. Specifically, the rear frame included in the liquid crystal module is viewed from the side where the reflection sheet and the linear light source are accommodated. It is. FIG. 2 is a schematic cross-sectional view at the position AA in FIG. In FIG. 2, for convenience of explanation, the diffusion plate, the optical sheet, and the liquid crystal panel are also shown by broken lines. Hereinafter, the liquid crystal module 50 according to the first embodiment will be described with reference to FIGS. 1 and 2.

  In the description of the liquid crystal module 50 according to the first embodiment, portions that overlap with the conventional liquid crystal module 100 shown in FIG.

  The liquid crystal module 50 according to the first embodiment includes a rear frame 1, a reflection sheet 2, a plurality of linear light sources 3 a (backlight light sources), a diffusion plate 4, an optical sheet 5, and a liquid crystal panel 6. Prepare. Since the configuration and function of each part are the same as those of the conventional liquid crystal module 100 described above, description thereof is omitted.

  Also in the first embodiment, the rear frame 1 is made of metal. The linear light source 3a is composed of a cold cathode fluorescent lamp (CCFL). For this reason, a luminance gradient may occur due to the leakage current based on the stray capacitance described above. However, in the liquid crystal module 50 of the first embodiment, the leakage current is reduced, and the occurrence of a luminance gradient is reduced. Hereinafter, a configuration for reducing the leakage current will be described.

  In the liquid crystal module 50 of the first embodiment, as in the conventional liquid crystal module 100, two linear light sources 3a are combined to form one U-shaped CCFL. However, the present invention is not limited to this configuration. That is, the linear light source 3a provided in the liquid crystal module 50 may be a straight tube type CCFL. Even in a straight tube type CCFL, since a leakage current based on stray capacitance is generated and a luminance gradient is generated, it is necessary to reduce the leakage current. And the structure which reduces the leakage current described below is effective not only for a U-shaped CCFL but also for a straight-tube CCFL.

  The plurality of (specifically, 16) linear light sources 3a included in the liquid crystal module 50 of the first embodiment are all in the longitudinal direction (the horizontal direction in FIG. 1 and the paper direction in FIG. 2). ), A plate-like insulator 21 extending in a strip shape is attached immediately below. Here, the entire area in the longitudinal direction of the linear light source 3a corresponds to the entire area of the portion that emits light for illuminating the liquid crystal panel 6 of the linear light source 3a.

  In the present embodiment, the linear light source 3a is held at one end by a lamp holder 7 (see FIG. 5) made of an insulator and at the other end by a lamp socket 8 (see FIG. 5) formed using the insulator. Then, an insulating lamp frame 11 as a protective cover is disposed thereon. For this reason, in this embodiment, this part does not correspond to the part which radiate | emits the light for illuminating the liquid crystal panel 6 of the linear light source 3a. In addition, since this part is already covered with the insulator, reduction of the leakage current is achieved even if the plate-like insulator 21 is not disposed.

  Since the plate-like insulator 21 is arranged immediately below the linear light source 3a, the use efficiency of the light emitted from the linear light source 3a is reduced when it does not have a function of reflecting light. As a result, the luminance of the liquid crystal module 50 is lowered. Therefore, the plate-like insulator 21 is provided so that the entire surface has a function of reflecting light. Accordingly, the plate-like insulator 21 is formed of the same material as that of the reflection sheet 2 placed on the rear frame 1, for example.

  Further, as shown in FIG. 1, the plate-like insulator 21 has a width W1 in the short direction when viewed in plan, and a width W2 in the short direction of the linear light source 3a (the lamp tube of the linear light source 3a). For example, the width W1 of the plate-like insulator 21 is about 1.5 to 2 times the width W2 of the linear light source 3a. And the plate-shaped insulator 21 is affixed on the linear light source 3a so that the linear light source 3a may be located in the approximate center part of the plate-shaped insulator 21 in the transversal direction.

  The linear light source 3a and the plate-like insulator 21 can be attached with, for example, an adhesive or a double-sided tape. The linear light source 3a of this embodiment consists of CCFL, and even if it sticks the plate-shaped insulator 21 to the linear light source 3a with such a thing, possibility that a joining member will deteriorate can be made low.

  As described above, according to the liquid crystal module 50 of the present embodiment, since the leakage current based on the stray capacitance of the linear light source 3a can be reduced, luminance unevenness in the liquid crystal module 50 can be reduced. And since the insulator 21 affixed on the linear light source 3a has a reflective function, it can avoid reducing the utilization efficiency of the light radiate | emitted from the linear light source 3a. Further, since the plate-like insulator 21 is provided in the form of a strip immediately below each linear light source 3a, even when the plate-like insulator 21 is formed of the same material as that of the reflection sheet 2, the reflection sheet 2 is simply used. Compared to reducing the leakage current by increasing the thickness of the sheet, it is possible to reduce the desired leakage current by reducing the amount of reflection sheet used, and to suppress the cost increase in the leakage current countermeasures as much as possible it can.

  Note that the width W1 of the plate-like insulator 21 is not limited to the configuration of the present embodiment. Further, the plate-like insulator 21 has a width W1 so that a desired luminance unevenness can be reduced by reducing a leakage current. What is necessary is just to determine suitably so that the cost required for the insulator 21 may not rise more than necessary by making the width W1 wide. Further, the shape of the plate-like insulator 21 is not limited to the band shape, and other forms may be employed.

  Moreover, in 1st Embodiment shown above, it was set as the structure which arrange | positions the plate-shaped insulator 21 over the whole region of the part which radiate | emits the light for illuminating the liquid crystal panel 6 of the linear light source 3a. It is not intended to be limited to this. For example, if the plate-like insulator 21 is arranged only in a part of the portion that emits light for illuminating the liquid crystal panel 6 of the linear light source 3a, the luminance unevenness generated in the liquid crystal module is in an allowable range. In such a case, the plate-like insulator 21 may be arranged only in a part thereof. However, as in the present embodiment, the configuration in which the plate-like insulator 21 is arranged over the entire portion of the portion that emits light for illuminating the liquid crystal panel 6 of the linear light source 3a has a higher leakage current. This is desirable because it can be effectively reduced.

(Second Embodiment)
Next, the liquid crystal module of the second embodiment will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the configuration of the liquid crystal module 60 of the second embodiment. FIG. 3A is a schematic sectional view showing the configuration of the liquid crystal module 60 of the second embodiment. b) is a schematic plan view showing a configuration of a plurality of linear light sources 3a included in the liquid crystal module 60 of the second embodiment. In FIG. 3B, not all of the plurality of linear light sources 3a are shown, and only a part thereof is shown.

  Since the liquid crystal module 60 of the second embodiment is the same configuration as the liquid crystal module 50 of the first embodiment except that the configuration of the insulator attached to the linear light source 3a is different, Only the differences will be described. Also in the second embodiment, each of the linear light sources 3a included in the liquid crystal module 60 has a reflection function over the entire area in the longitudinal direction (this definition is the same as in the case of the first embodiment). An insulator 22 (for example, one made of the same material as the reflection sheet 2) is provided.

  When viewed in plan, the insulator 22 is in a state of extending in a strip shape in the longitudinal direction of the linear light source 3a as in the case of the first embodiment. However, this insulator 22 is not a plate-like insulator as in the first embodiment, but is curved into a substantially semicircular shape so as to surround the lower half of the linear light source 3a. It differs from the insulator 21 of the first embodiment in that it is affixed.

  In the present embodiment, the curved insulator 22 is configured such that the entire surface in contact with the linear light source 3a is attached to the linear light source 3a. However, the present invention is not intended to be limited to such a configuration, and various modifications can be made without departing from the object of the present invention. That is, for example, only the lowermost part of the curved insulator 22 may be attached to the linear light source 3a, the other parts may not be attached, and a part of the linear light source 3a may be surrounded. Moreover, in this embodiment, although the insulator 22 becomes a semicircle shape by curving, it does not necessarily need to be a semicircle shape.

  When the liquid crystal module 60 is formed as in the present embodiment, the leakage current based on the stray capacitance of the linear light source 3a can be reduced as in the case of the first embodiment. For this reason, luminance unevenness in the liquid crystal module 60 can be reduced. Since the insulator 22 having a reflecting function is curved and surrounds a part of the linear light source 3a, the reflected light rate by the insulator 22 is higher than that of the insulator 21 in the first embodiment. Increase. That is, the liquid crystal module 60 of the present embodiment can increase the utilization efficiency of the light emitted from the linear light source 3a as compared with the liquid crystal module 50 of the first embodiment. Further, as in the first embodiment, even when the curved insulator 22 is formed of the same material as that of the reflection sheet 2, it is more reflective than when the thickness of the reflection sheet 2 is simply increased to reduce the leakage current. It is possible to reduce the desired leakage current by reducing the amount of sheet used, and the cost increase in the countermeasure against leakage current can be suppressed as much as possible.

(Third embodiment)
Next, a liquid crystal module according to a third embodiment will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view showing the configuration of the liquid crystal module 70 of the third embodiment. In the description of the liquid crystal module 70 of the third embodiment, portions that overlap with the liquid crystal modules 50 and 60 of the first and second embodiments are denoted by the same reference numerals, unless otherwise required. Description is omitted.

  In the liquid crystal module 70 of the third embodiment, as in the first and second embodiments, in order to reduce the leakage current generated in the portion where the linear light source 3a emits light for illuminating the liquid crystal panel 6 This is common in that an insulator is disposed between the linear light source 3a and the rear frame 1 separately from the reflection sheet 2. However, in the third embodiment, unlike the first and second embodiments, an insulator provided separately from the reflective sheet 2 is not attached to the linear light source 3a.

  In the liquid crystal module 70 of the third embodiment, the insulator 23 provided separately from the reflection sheet 2 is disposed between the reflection sheet 2 and the rear frame 1. And the insulator 23 is arrange | positioned so that the whole bottom face 1a of the rear frame 1 may be covered. Since the insulator 23 is disposed between the reflection sheet 2 and the rear frame 1, it is not necessary to have a function of reflecting the light emitted from the linear light source 3 a, for example, compared to the reflection sheet 2. For example, it can be a cheap material such as rubber.

  In addition, in this embodiment, although it is the structure which covers the whole bottom face 1a of the rear frame 1, it is not the meaning limited to this, The structure which covers only a part of the bottom face 1a of the rear frame 1 with the insulator 23 depending on the case. It does not matter.

  Even in the case of the configuration as in the present embodiment, the thickness of the insulator disposed between the linear light source 3a and the rear frame 1 by the insulator 23 disposed between the reflective sheet 2 and the rear frame 1. As in the case of the first and second embodiments, the leakage current based on the stray capacitance of the linear light source 3a can be reduced. For this reason, luminance unevenness in the liquid crystal module 70 can be reduced. In addition, since an insulator disposed between the linear light source 3a and the rear frame 1 can be achieved using an inexpensive material, it is more than the case where the thickness of the reflection sheet 2 is increased to reduce the leakage current. The reduction of leakage current can be realized at low cost.

(Other)
In the present embodiment, the case of a cold cathode fluorescent lamp (CCFL) has been described as a linear light source that generates a leakage current based on stray capacitance. However, for a liquid crystal module that includes a linear light source that generates a similar leakage current. The present invention is widely applicable.

  If the liquid crystal module of the present invention is used, the leakage current based on the stray capacitance generated in a linear light source such as a cold cathode fluorescent lamp (CCFL) can be reduced while suppressing an increase in cost. For this reason, this invention is useful as a technique regarding a liquid crystal module.

These are the schematic plan views which show a part of liquid crystal module of 1st Embodiment. These are schematic sectional drawings in the AA position of FIG. These are explanatory drawings for demonstrating the structure of the liquid crystal module of 2nd Embodiment. These are schematic sectional drawings which show the structure of the liquid crystal module of 3rd Embodiment. These are the exploded perspective views which show the structure of the conventional liquid crystal module. These are the schematic diagrams for demonstrating the problem in the conventional liquid crystal module.

Explanation of symbols

1 Rear frame (metal frame)
2 Reflective sheet 3a Linear light source 6 Liquid crystal panel 21, 22, 23 Insulator 50, 60, 70 Liquid crystal module

Claims (5)

LCD panel,
A plurality of linear light sources arranged on the back side of the liquid crystal panel;
A reflective sheet that is disposed on the side opposite to the side on which the liquid crystal panel is disposed with respect to the linear light source, and reflects light emitted from the linear light source;
A metal frame disposed on the side opposite to the side on which the linear light source is disposed with respect to the reflection sheet, and the reflection sheet placed thereon;
In a liquid crystal module comprising:
An insulator that reduces leakage current generated in a portion of the linear light source that emits light for illuminating the liquid crystal panel is disposed separately from the reflective sheet between the linear light source and the metal frame. LCD module characterized by   The liquid crystal module according to claim 1, wherein the insulator is provided so as to be able to reflect light emitted from the linear light source and is attached to each of the plurality of linear light sources.   The liquid crystal module according to claim 2, wherein the insulator is provided in a planar view along the longitudinal direction of the linear light source.   The liquid crystal module according to claim 3, wherein the insulator is provided so as to be curved and surround a part of the linear light source.   5. The liquid crystal module according to claim 2, wherein the insulator is provided over the entire portion of the linear light source that emits light for illuminating the liquid crystal panel. 6.

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