JP2011138705A - Liquid crystal panel module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel module that reduces irregular luminance caused by temperature difference of a lamp after the liquid crystal panel is turned on. <P>SOLUTION: A thermochromic material is applied to a surface of a reflective plate of the liquid crystal panel module, reflectance in regions other than proximity of supporting members are adjusted according to temperature, the luminance difference caused by the temperature difference is minimized in proximity of the lamp supporting members and other regions other than the proximity of the supporting members, and light amount to reach the crystal liquid panel is equalized. Thus, the irregular luminance caused by the temperature difference after the crystal liquid panel is turned on can be reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal panel module using a lamp in a backlight unit.

  In recent years, with an increase in the size of a display device such as a television using a liquid crystal panel, a fluorescent lamp used for the backlight has become longer. Further, since the fluorescent lamp has a higher luminous efficiency as the tube inner diameter is smaller, the tube is narrowed in addition to the longer tube, and the mechanical strength of the fluorescent lamp alone is very weak. Therefore, it is very important to support the fluorescent lamp in the liquid crystal panel.

  In a liquid crystal panel, for example, a cold cathode tube is used as a fluorescent lamp, but a support member that supports the fluorescent lamp is arranged at one or a plurality of positions between both ends of the fluorescent lamp and the middle of the fluorescent lamp. . Since the support member is in contact with the fluorescent lamp, heat transfer occurs in the contact portion, and the temperature rise of the fluorescent lamp in the vicinity of the contact portion is delayed as compared with the portion away from the contact portion. When the temperature of the fluorescent lamp is low, the light emission efficiency is lowered, and therefore the luminance near the contact portion of the fluorescent lamp is lowered for a while after the start of lighting. The uneven brightness of the display panel is called uneven brightness. If there is uneven brightness, the uneven brightness of the screen is conspicuous and the display device becomes very difficult to see.

  In order to prevent a temperature drop at the contact portion of the fluorescent lamp with the support member, it has been proposed to reduce the magnitude of the heat transfer. For example, a liquid crystal display device has been devised that employs a fluorescent tube holder having a polygonal grip shape, supports the fluorescent tube at a predetermined position, reduces the contact area with the fluorescent tube, and reduces uneven brightness due to heat conduction. (For example, refer to Patent Document 1).

JP 2006-127877 A

  As described in Patent Document 1, even if the contact area between the fluorescent lamp support member and the fluorescent lamp is reduced, heat transfer occurs, and the temperature of the contact portion is slower than that of the portion away from the contact portion. Thus, a luminance difference occurs for a while after the power is turned on, which may cause luminance unevenness.

  The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a liquid crystal panel module capable of reducing luminance unevenness due to a temperature difference of a lamp after the liquid crystal panel is powered on. And

  In order to achieve the above object, a liquid crystal panel module of the present invention includes a lamp, a reflecting plate that reflects light from the lamp, and a support member that supports the lamp on the reflecting plate. The reflectance is adjusted according to the temperature.

  According to the present invention, it is possible to reduce luminance unevenness due to the temperature difference of the fluorescent lamp after the liquid crystal panel is powered on.

The figure which showed the schematic structure of the liquid crystal panel module 1 by this invention. The figure which showed the temperature change of the lamp | ramp. The figure which showed the brightness | luminance change of the lamp | ramp. The figure which showed the brightness | luminance difference of parts other than the supporting member vicinity of a lamp | ramp, and the supporting member vicinity. The figure which showed the reflecting plate with which the thermochromic coating material was apply | coated. The figure which showed the change of the temperature of a reflecting plate. The figure which showed the change of the reflectance of the area | region except the support member vicinity of a reflecting plate. The figure which showed the change of the reflectance of the area | region except the support member vicinity of a reflecting plate. The figure which showed the temperature characteristic requested | required of a thermochromic coating material. The figure which showed the change of the reflectance of the area | region except the support member vicinity in Embodiment 2. FIG. The figure which showed the change of the reflectance of the area | region except the support member vicinity in Embodiment 2. FIG. The figure which showed the temperature characteristic of the thermochromic coating material in Embodiment 2. FIG. FIG. 6 shows a liquid crystal panel module in Embodiment 3.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a schematic configuration of the liquid crystal panel module 1. The liquid crystal panel module 1 includes a frame 2 that supports the entire liquid crystal panel module 1, a liquid crystal panel 3 including a diffusion plate, and a backlight unit 4. FIG. 1A is a view of the liquid crystal panel module 1 as viewed from the front with the liquid crystal panel 3 removed. FIG. 1B is a cross-sectional view taken along the line AA in FIG. FIG. 1A corresponds to the BB cross section in FIG.

  A circuit board (not shown) is disposed on the back surface of the frame 2. A diffusion plate (not shown) is disposed on the backlight unit 4 side of the liquid crystal panel 3. A backlight unit 4 is disposed between the frame 2 and the liquid crystal panel 3.

  The backlight unit 4 includes a lamp 5, an electrode holder 6 that supports the lamp 5 at both ends and supplies power to the lamp, a reflecting plate 7 that reflects light from the lamp 5, and the lamp 5 as the reflecting plate 7 or the frame 2. It is comprised from the supporting member 8 supported with respect to.

  The lamp 5 is a fluorescent lamp, and for example, a cold cathode tube or a hot cathode tube is used. A plurality of lamps 5 are used to increase the brightness of the liquid crystal panel 3 or to prevent uneven brightness of the liquid crystal panel. The lamp 5 is connected via an electrode holder 6 to an inverter (not shown) installed on the back surface of the frame 2.

  In order to display the liquid crystal panel 3 brighter in the direct type system in which the lamps 5 are arranged on the back surface of the liquid crystal panel 3, the reflector 7 is used. The reflecting plate 7 reflects light emitted in the opposite direction to the liquid crystal panel 3 and sends it back to the liquid crystal panel 3 side to reduce light loss and improve the luminance of the liquid crystal panel 3.

  The lamp 5 is supported by a support member 8 at a plurality of places or at one place other than both ends so as to withstand shock and vibration. The support member 8 is fixed to the frame 2 and has a function of supporting the lamp 5 with respect to the frame 2 and supporting the lamp 5 with respect to the reflection plate 7.

  The luminous efficiency of the lamp 5 is affected by the ambient temperature (lamp tube wall temperature), and there is an optimum temperature at which the luminous efficiency is maximized. When the temperature is lower than the optimum temperature, the luminous efficiency is lowered, so that the luminance is smaller than that at the optimum temperature. In the backlight unit 4 having the above configuration, when the lamp 5 is turned on from the extinguished state, the heat of the lamp 5 in the vicinity of the support member 8 is conducted through the support member 8 and is dissipated to the frame 2. Until the temperature of the lamp 5 rises and the temperature of the lamp 5 is saturated, the temperature of the lamp 5 in the vicinity of the support member 8 is lower than that in a portion other than the vicinity of the support member 8 (a portion away from the support member 8). Therefore, the brightness of the lamp near the support member 8 is lower than the portion other than the vicinity of the support member 8 until the temperature is saturated and the entire temperature distribution is uniform.

  In the reflector 7, a thermochromic material that adjusts the reflectance of the region excluding the vicinity of the support member 8 according to the temperature is laid on the surface facing the lamp. It is laid over substantially the entire surface excluding a region 9 indicated by an ellipse near the support member 8. In FIG. 1A, the thermochromic paint is applied to the portion of the reflector 7 indicated by the oblique lines. The thermochromic material will be described later.

  FIG. 2 is a diagram showing a temperature change of the lamp. The horizontal axis represents time, the lighting start time of the lamp 5 is 0, and the time when the temperature of the lamp 5 near the support member 8 is substantially saturated is Ss. The vertical axis indicates the temperature of the lamp 5. The temperature at the start of lighting of the lamp 5 is Ti, indicating that Ts is reached when the temperature is saturated.

  The temperature of the portion other than the vicinity of the support member 8 increases with the start of lighting, and reaches the saturation temperature before reaching the time Ss. On the other hand, the temperature rise in the vicinity of the indicating member 8 is delayed as compared with the portion other than the vicinity of the supporting member 8. For example, when the time is S1, the temperature in the portion other than the vicinity of the support member 8 is T1, whereas the temperature in the vicinity of the support member 8 is T2 (T1> T2). At time Ss, the temperature in the vicinity of the indicating member 8 reaches Ts.

  FIG. 3 is a diagram showing a change in luminance of the lamp 5. The change in luminance of the lamp 5 changes at a change rate substantially similar to the temperature change of the lamp 5. The horizontal axis represents time, the lighting start time of the lamp 5 is 0, and the time when the temperature of the lamp 5 is substantially saturated is Ss. The vertical axis represents the luminance of the lamp 5. It is Ci at the start of lighting of the lamp 5, and indicates Cs when the temperature is saturated.

  The brightness of the portion other than the vicinity of the support member 8 increases with the temperature rise after the start of lighting, reaches the saturation temperature before reaching the time Ss, and the brightness is also Cs. On the other hand, the brightness in the vicinity of the indicating member 8 is delayed in the increase in temperature compared with the portion other than in the vicinity of the support member 8, so that the increase in brightness is also delayed. For example, when the time is S1, the luminance in the portion other than the vicinity of the support member 8 is C1, whereas the luminance in the vicinity of the indicating member 8 is C2 (C1> C2). At time Ss, the brightness near the indicating member 8 reaches Cs.

  FIG. 4 is a diagram showing the luminance difference between the vicinity of the support member 8 and the portion other than the vicinity of the support member 8 of the lamp 5. There is no difference in luminance immediately after the start of lighting and in Ss where the temperature in the vicinity of the indicating member 8 reaches the saturation temperature Ts. The luminance difference is the largest in the vicinity where the temperature difference between the vicinity of the support member 8 and the portion other than the vicinity of the support member 8 is the largest. In FIG. 2, FIG. 3, and FIG. 4, the time in the vicinity of the largest temperature difference is indicated as S1. The luminance difference Cd in FIG. 4 is Cd = C1−C2.

  Since the luminance difference after the lamp 5 is turned on contributes to the luminance unevenness, the luminance unevenness can be reduced by reducing the luminance difference. As one means for reducing the difference in luminance, the amount of reflected light in the region other than the vicinity of the support member 8 is reduced by adjusting the reflectance of the region other than the vicinity of the support member 8 in the reflector 7 according to the temperature. It is conceivable to make the amount of light reaching the liquid crystal panel 3 uniform.

  A thermochromic paint 10 whose transmittance varies with temperature is applied to the surface of the region excluding the vicinity of the support member 8 of the reflector 7 and the reflectance of the region excluding the vicinity of the support member 8 of the reflector 7 is adjusted according to the temperature. As a result, the amount of light reaching the liquid crystal panel 3 can be made uniform.

  FIG. 5 is a view showing the reflector 7 to which the thermochromic paint 10 is applied. In order to show the state of application | coating, it is the figure which deleted the lamp | ramp 5 from Fig.1 (a). A region 9 indicated by an ellipse is a region near the support member 8. The size of the region 9 may be appropriately determined while observing the reflected light amount. The region 9 is shown as an ellipse, but it may be a circle or a rectangle. The thermochromic paint 10 is applied to the area (area shown by hatching) excluding the area 9 on the surface of the reflection plate 7.

  FIG. 6 is a diagram showing a change in the temperature of the reflecting plate 7. The temperature of the region excluding the vicinity of the support member 8 of the reflecting plate 7 rises due to the heat released from the lamp 5. The temperature rises slightly later than the temperature change in the vicinity of the support member 8 of the lamp 5 indicated by the two-point difference line, reaches the saturation temperature at time Ss, and reaches the saturation temperature at time S2. In this state, the backlight unit 4 is in a steady state with respect to temperature. The temperature of the reflecting plate 7 at time S1 is T3.

  FIG. 7 is a diagram showing an ideal change in reflectance in a region excluding the vicinity of the support member 8 of the reflection plate 7. The horizontal axis represents time, the lighting start time of the lamp 5 is 0, and the time when the temperature of the lamp 5 near the support member 8 is substantially saturated is Ss. The vertical axis represents the reflectance of the reflecting plate 7. The reflectance at the start of lighting of the lamp 5 is Ri. The reflectance Ri is the reflectance of the reflector 7 in a state where the thermochromic paint 9 is not applied. Accordingly, the reflectance of the region 9 is Ri, and is a constant reflectance regardless of the passage of time and temperature.

  The reflectance is R1 (R1 <Ri) when the time S1 elapses after the lamp 5 is turned on. As the luminance difference increases with the passage of time, the reflectance decreases, and at time S1 in the vicinity where the luminance difference becomes the largest, the reflectance becomes the smallest. When time further elapses and Ss is reached, the reflectance returns to Ri. If the reflectance of the region excluding the vicinity of the support member 8 of the reflector 7 changes in response to the change in temperature in this way, the amount of reflected light in the region excluding the vicinity of the support member 8 is adjusted to reach the liquid crystal panel 3. The amount of light can be made uniform and luminance unevenness can be reduced.

  FIG. 8 is a diagram showing an ideal change in reflectance in a region excluding the vicinity of the supporting member 8 of the reflecting plate 7. FIG. 8 shows the change in reflectance when the horizontal axis is temperature. Immediately after the lamp 5 is turned on, the temperature on the surface of the reflector 7 is Ti, and the reflectance at this time is Ri. Near time S1, when the temperature on the surface of the reflecting plate 7 becomes T3, the reflectance is R1.

  Further, when time elapses and time Ss is reached, saturation temperature Ts is reached, and the reflectance returns to Ri. The reflectance of the reflecting plate 7 becomes the most reduced reflectance R1 at the temperature T3 according to the temperature change of the reflecting plate 7, and returns to the same Ri as the initial state at the temperature Ts.

  FIG. 9 is a diagram showing temperature characteristics required for the thermochromic paint 10. This is a temperature characteristic required to realize an ideal reflectance change in a region excluding the vicinity of the support member 8 of the reflector 7 shown in FIGS. The characteristic of the transmittance with respect to the temperature of the thermochromic coating 10 is determined so that the characteristic of the target value of the reflectance shown in FIG. 8 can be obtained. When the surface temperature of the reflecting plate 7 is Ti, the thermochromic coating 10 has a transmittance of approximately 100%, and the reflectance of the reflecting plate 7 is Ri at this time. When the surface temperature of the reflecting plate 7 becomes T3, the transmittance becomes a value P1 in the vicinity showing the smallest value, and at this time, the reflectance of the reflecting plate 7 becomes R1.

  Further, when the surface temperature of the reflecting plate 7 reaches Ts, the transmittance returns to approximately 100%, and thus the reflectance of the reflecting plate 7 becomes Ri. What is necessary is just to determine the transmittance | permeability P1 so that the reflectance of the reflecting plate 7 may become R1 in temperature T3.

  Various materials are known as the thermochromic material 10. For example, as an organic temperature indicating ink, a dye structure is formed at the time of discoloration and becomes a leuco body at the time of colorless, and the polarities of the electron donor and the electron acceptor. Materials that occur by an electron transfer mechanism by thermal equilibrium in a compound are known. In addition, there are other materials that have discoloration characteristics due to thermal decomposition (eg, metal salts), crystal transition (eg, metal complex salts), changes in molecular orientation (eg, crystals), etc. A filling material may be used.

  Although the embodiment in which the thermochromic coating 10 is applied to the reflecting plate 7 has been described, a sheet coated with the thermochromic coating may be attached to the reflecting plate 7. Moreover, you may stick the thin plate by a thermicomic material to a reflecting plate. Furthermore, a method is also conceivable in which a reflector is molded from a thermochromic material and a sheet having a reflectance of Ri is applied to the region 9.

  As described above, the thermochromic material 10 is applied to the surface of the reflecting plate 7, and the reflectance in the region excluding the vicinity of the support member 8 is adjusted according to the temperature, and the vicinity of the support member 8 and the vicinity of the support member 8 of the lamp 5. The brightness difference due to the temperature difference of the part can be reduced, the amount of light reaching the liquid crystal panel 3 can be made uniform, and the brightness unevenness caused by the temperature difference of the lamp after the liquid crystal panel is turned on can be reduced.

(Embodiment 2)
FIG. 10 is a diagram showing a change in reflectance in a region excluding the vicinity of the support member 8 in the second embodiment. The liquid crystal panel module 1 in the second embodiment is the same as each part of the liquid crystal panel module 1 in the first embodiment shown in FIG. The difference from the first embodiment is that the temperature characteristics of the thermochromic coating 11 are different from those of the thermochromic 10 of the first embodiment. In the case where it is difficult to obtain a thermochromic material having temperature characteristics as shown in FIG. 9, the predetermined transmittance is maintained at a temperature lower than the first temperature, and the temperature is higher when the temperature is higher than the first temperature. By using a thermochromic material that has a transmittance that decreases with the increase and has a transmittance of approximately 100% near the second temperature, it is possible to reduce uneven brightness due to the temperature difference of the lamp. .

  The dashed line in FIG. 10 is the target value in FIG. The amount of light reaching the liquid crystal panel 3 is predominantly the amount of light reaching directly from the lamp 5. In particular, since the amount of light is small as a whole from the start of lighting until the brightness difference becomes large, direct light is dominant, and the adjustment effect by the amount of reflected light is small. Therefore, it is conceivable that the reflectance is set to R1 until the time S1 after the lighting elapses, and the reflectance is increased after time S1 to set the reflectance at Ps to Ri. The reflectance is R1 (R1 <Ri) from the lighting start time of the lamp 5 until time S1.

  FIG. 11 is a diagram showing a change in reflectance in a region excluding the vicinity of the support member 8 of the reflector 7 in the second embodiment. It is a figure at the time of taking temperature on the horizontal axis | shaft the change of the reflectance of the reflecting plate 7 in FIG. Immediately after the lamp 5 is turned on, the temperature on the surface of the reflecting plate 7 is Ti, and the reflectance at this time is R1. Near time S1, when the temperature on the surface of the reflecting plate 7 reaches T3, the reflectance remains R1. Further, when time elapses and time Ss is reached, the saturation temperature Ts is reached, and the reflectance becomes Ri. The reflectance of the reflecting plate 7 is constant at the value of R1 until the temperature T3, rises from above T3, and becomes Ri at the temperature Ts.

  FIG. 12 is a diagram showing temperature characteristics of the thermochromic paint 11 in the second embodiment. The characteristic of the transmittance with respect to the temperature of the thermochromic paint 11 is determined so that the characteristic of the target value of the reflectance shown in FIG. 11 is obtained. The thermochromic coating 11 has a transmittance of P1 at a temperature lower than the temperature near the first temperature T3. When the temperature becomes higher than the temperature near the first temperature T3, the transmittance decreases as the temperature rises. In the vicinity of the temperature Ts of 2, the transmittance is approximately 100%.

  When the surface temperature of the reflecting plate 7 is Ti, the thermochromic coating 11 has a transmittance of P1 for the thermochromic coating 10, and the reflectance of the reflecting plate 7 at this time is R1. Until the surface temperature of the reflecting plate 7 reaches T3, the transmittance is P1, and at this time, the reflectance R1 remains. After the temperature T3 is exceeded, the transmittance increases. When the temperature reaches Ts, the transmittance is approximately 100%, and the reflectance of the reflector 7 is Ri. The temperature characteristic of the thermochromic coating 11 may be determined so that the transmittance is P1 when the temperature is from Ti to T3, and increases after T3 and becomes approximately 100% at Ts.

  As described above, a certain transmittance is maintained below the first temperature, and when the temperature is equal to or higher than the first temperature, the transmittance decreases as the temperature rises, and the transmittance becomes approximately 100% at the second temperature. By applying a suitable thermochromic material 11 to the surface of the reflector 7, the reflectance of the region other than the vicinity of the support member 8 is adjusted according to the temperature, and the portions of the lamp 5 other than the vicinity of the support member 8 and the vicinity of the support member 8 The brightness difference due to the temperature difference can be reduced, the amount of light reaching the liquid crystal panel 3 can be made uniform, and the brightness unevenness caused by the temperature difference of the lamp after the liquid crystal panel is turned on can be reduced.

(Embodiment 3)
FIG. 13 is a diagram showing the liquid crystal panel module 20 in the third embodiment. In this method, the thermochromic paint 22 is partially disposed on a part of the reflector 7 of the backlight unit 21 to reduce luminance unevenness. If there is an effect of reducing luminance unevenness in the luminance distribution of the liquid crystal panel 3, the thermochromic paint 22 may be discretely arranged.

  Although the form which apply | coats the thermochromic coating material 22 to the reflecting plate 7 was demonstrated, you may affix the sheet | seat which apply | coated the thermochromic coating material 22 to the reflecting plate. Moreover, you may stick the thin plate by a thermicomic material to a reflecting plate.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Liquid crystal panel module 2 Frame 3 Liquid crystal panel 4 Backlight unit 5 Lamp 6 Electrode holder 7 Reflector 8 Support member 9 Area 10 Thermochromic paint 11 Thermochromic paint 20 Liquid crystal panel module 21 Backlight unit 22 Thermochromic paint

Claims (6)

A lamp,
A reflector that reflects light from the lamp;
A support member for supporting the lamp on the reflector,
The liquid crystal panel module, wherein the reflection plate adjusts the reflectance according to temperature.   2. The reflector according to claim 1, wherein the reflectance of a region excluding the vicinity of the support member increases with an increase in temperature of the reflector when the temperature of the reflector is higher than a predetermined temperature. LCD panel module.   2. The liquid crystal panel module according to claim 1, wherein a material for adjusting the reflectivity of a region excluding the vicinity of the support member according to temperature is disposed on a surface of the reflector that faces the lamp. .   4. The liquid crystal panel according to claim 3, wherein the material raises the reflectivity of a region excluding the vicinity of the support member as the temperature of the reflector increases when the temperature of the reflector is higher than a predetermined temperature. module.   The liquid crystal panel module according to claim 3, wherein the material is a thermochromic material.   The material maintains a predetermined transmittance at a temperature lower than the first temperature, the transmittance decreases as the temperature rises when the temperature is higher than the first temperature, and the transmittance is approximately near the second temperature. The liquid crystal panel module according to claim 5, wherein the liquid crystal panel module is 100%.

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