JP2010003582A - Illuminating device, display, and television receiving set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device in which an optical member such as an optical sheet is fixed certainly, and wrinkles and bending are hardly generated even if a temperature change in use environment occurs, and which can emit uniform light and has superior quality. <P>SOLUTION: The illumination device 12 is provided with a light source 17 and an optical member 15 arranged on a light outgoing part 15z side of the light source 17. The optical member 15 is pinched by a pair of pinching members and the pinching member is provided with a first pinching member 14 to pinch the optical member 15 from the light source 17 side and second pinching members 16, 16a to pinch the optical member 15 from the opposite side to the light source 17 side. A cushion member 70 is interposed between the optical member 15 and the second pinching members 16, 16a, and the cushion member 70 is equipped with a piezoelectric element 72. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lighting device, a display device, and a television receiver.

Since a liquid crystal panel used for a liquid crystal display device such as a liquid crystal television does not emit light, a backlight device is separately required as a lighting device. Such a backlight device is installed on the back side of the liquid crystal panel (on the side opposite to the display surface), and has a large number of light sources and an optical sheet disposed on the light emission side of the light sources. The thing of the structure which was comprised is well-known (refer patent document 1).
JP 2007-24913 A

  In the technique disclosed in Patent Document 1, the upper side of the optical sheet surface on which a plurality of optical sheets are suspended is pressed with a sponge-like cushioning material, thereby slowing down the optical sheet due to temperature and humidity changes in the usage environment. The expansion and contraction of the optical sheet is not a restriction, and the displacement of each optical sheet is limited by the frictional resistance between the optical sheets for steep and frequent movements such as vibration and impact during product transportation. It is supposed that the generation of dust due to friction can be prevented.

  However, even in the case of pressing with a sponge-like cushioning material, whether or not it becomes a constraint on the slow expansion and contraction of the optical sheet due to changes in temperature and humidity in the use environment largely depends on the degree of the pressing force. . That is, even if a sponge-like cushioning material is used, if the pressing force is designed to be large enough to hold the optical sheet, there may be restrictions on the expansion and contraction of the optical sheet due to changes in temperature and humidity. And when restrictions arise with respect to the expansion and contraction of the optical sheet in this way, wrinkles and bends occur in the optical sheet, and unevenness of the emitted light may occur at the locations where the wrinkles and bends occur.

The present invention securely fixes an optical member such as an optical sheet, and emits uniform light without causing wrinkles or bending in the optical member even when the temperature of the usage environment changes. Therefore, it is an object to provide a lighting device that can be used and has excellent quality.
It is another object of the present invention to provide a display device provided with such a lighting device and a television receiver provided with such a display device.

  In order to solve the above problems, an illumination device of the present invention is an illumination device including a light emitting unit that emits light, and includes a light source and an optical member disposed on the light emitting unit side of the light source. The optical member is sandwiched between a pair of sandwiching members, the sandwiching member including a first sandwiching member that sandwiches the optical member from the light source side, and the optical member on the side opposite to the light source side. And a second clamping member sandwiched between the optical member and the first clamping member, or at least one of the optical member and the second clamping member with a buffer member interposed therebetween. The buffer member comprises a piezoelectric element.

  According to such an illumination device, since the buffer member includes the piezoelectric element, it is possible to change the thickness of the buffer member by applying a voltage to the piezoelectric element. Specifically, the size (thickness) of the buffer member can be changed in the direction (thickness direction) sandwiched between the optical member and the sandwiching member in accordance with the voltage application. Thus, for example, even when the optical member expands or contracts due to a change in the usage environment (temperature change) of the lighting device, a voltage is applied to the piezoelectric element so as to reduce the size in the direction in which the buffer member is sandwiched. If (including non-application) is performed, the clamping force (pressing force) on the optical member becomes small, and there is no restriction on the expansion and contraction. As a result, the optical member can freely expand and contract, and the optical member is less likely to wrinkle or bend, and can emit uniform light. On the other hand, when the optical member does not expand and contract, voltage application (including non-application) is applied to the piezoelectric element so as to increase the size in the direction in which the buffer member is sandwiched. It can be fixed with a sufficient clamping force (pressing force). As described above, according to the present invention, the optical member is securely fixed, and even when the temperature change of the usage environment occurs, the optical member is less likely to wrinkle or bend, and emits uniform light. It is possible to provide a lighting device with excellent quality that can be performed.

The lighting device may include a power supply unit that applies a voltage to the piezoelectric element, and the power supply unit may control voltage application to the piezoelectric element according to a temperature change of the lighting device. .
The optical member expands and contracts according to the temperature change of the lighting device. Therefore, if the voltage application to the piezoelectric element is controlled according to the temperature change of the lighting device, the size of the direction in which the piezoelectric element is sandwiched can be changed at the time of the temperature change. The optical member can be freely expanded and contracted, and the optical member can hardly be wrinkled or bent.

Specifically, when the temperature of the lighting device changes, the power supply unit is configured so that the piezoelectric element is deformed small in a direction in which the piezoelectric element is sandwiched between the optical member and the sandwiching member. It is possible to control voltage application to the piezoelectric element.
As a result, the optical member can be freely expanded and contracted, and the optical member can hardly be wrinkled or bent.

The illumination device further includes a power supply unit that applies a voltage to the piezoelectric element, and the power supply unit changes when the light source changes from a non-lighting state to a lighting state or from a lighting state to a non-lighting state. In doing so, the voltage application state to the piezoelectric element can be switched.
When the lighting state of the light source changes, a temperature change occurs. That is, when the light source is turned on, heat is generated by light emission, resulting in a temperature increase, and when the light source is turned off, a temperature decrease is generated. Therefore, when the lighting state of the light source changes, the optical member expands and contracts. Therefore, if the voltage application state for the piezoelectric element is switched according to the lighting change of the light source, the size of the direction in which the piezoelectric element is sandwiched can be changed at the time of the lighting change. Free expansion and contraction are possible, and it becomes possible to make the optical member difficult to cause wrinkles and deflection.

In the illumination device, the buffer member is configured such that the piezoelectric element is disposed on the clamping member side, and a foam member having a higher elastic modulus than the piezoelectric element is disposed on the optical member side. be able to.
By arranging the foamed member on the optical member side in this way, it is difficult for the optical member to be rubbed, and it is preferable to cause a problem that abnormal noise is generated due to the rub or the optical member is scratched. Can be prevented.

Next, in order to solve the above problem, a display device of the present invention includes the above-described illumination device and a display panel that performs display using light from the illumination device.
According to such a display device, since it is possible to irradiate the display panel with uniform light from the illumination device, it is possible to realize display with excellent display quality.

  An example of the display panel is a liquid crystal panel. Such a display device can be applied as a liquid crystal display device to various uses such as a display of a television or a personal computer, and is particularly suitable as an ultra-thin television receiver.

  According to the present invention, an optical member such as an optical sheet is securely fixed, and even if a change in the temperature of the usage environment occurs, the optical member is less likely to wrinkle or bend, and emits uniform light. Therefore, it is possible to provide a lighting device with excellent quality. In addition, according to the present invention, it is possible to provide a high-quality display device provided with such a lighting device and a high-quality television receiver provided with such a display device.

Embodiments of the present invention will be described with reference to the drawings.
1 is an exploded perspective view showing a schematic configuration of the television receiver of the present embodiment, FIG. 2 is an exploded perspective view showing a schematic configuration of a liquid crystal display device included in the television receiver of FIG. 1, and FIG. 3 is a liquid crystal display of FIG. 4 is an enlarged cross-sectional view of a main part showing a cross-sectional configuration along the short side direction of the device, FIG. 4 is an enlarged cross-sectional view of a main part showing a cross-sectional configuration along the long side direction of the liquid crystal display device of FIG. FIG. 6 is an explanatory view showing a configuration of a piezoelectric element provided in the buffer member, FIG. 7 is a block diagram showing a configuration of a piezoelectric element driving mechanism, and FIG. 8 is a piezoelectric element. FIG. 9 is an explanatory view showing a thickness decreasing aspect of the piezoelectric element.

  As shown in FIG. 1, the television receiver TV according to the present embodiment includes a liquid crystal display device 10, front and back cabinets Ca and Cb that are accommodated so as to sandwich the liquid crystal display device 10, a power source P, a tuner T, And a stand S. The liquid crystal display device (display device) 10 has a horizontally long rectangular shape as a whole and is accommodated in a vertically placed state. As shown in FIG. 2, the liquid crystal display device 10 includes a liquid crystal panel 11 that is a display panel and a backlight device (illumination device) 12 that is an external light source, which are integrated by a frame-like bezel 13 or the like. Is supposed to be retained.

Next, the liquid crystal panel 11 and the backlight device 12 constituting the liquid crystal display device 10 will be described (see FIGS. 2 to 4).
The liquid crystal panel (display panel) 11 is configured such that a pair of glass substrates are bonded together with a predetermined gap therebetween, and liquid crystal is sealed between the glass substrates. One glass substrate is provided with a switching element (for example, TFT) connected to a source wiring and a gate wiring orthogonal to each other, a pixel electrode connected to the switching element, an alignment film, and the like. The substrate is provided with a color filter and counter electrodes in which colored portions such as R (red), G (green), and B (blue) are arranged in a predetermined arrangement, and an alignment film. In addition, polarizing plates 11a and 11b are disposed outside both substrates (see FIGS. 3 and 4).

  As shown in FIG. 2, the backlight device 12 includes a chassis 14 having a substantially box shape opened on the light emitting surface side (the liquid crystal panel 11 side), and a diffusion plate attached so as to cover the opening 14 b of the chassis 14. 15a and an optical member 15 consisting of an optical sheet group 15b disposed on the light emitting surface side further than the diffusion plate 15a, and the optical member 15 is disposed along the long side of the chassis 14 so that the optical member 15 is the chassis 14 (clamping member). And a long-side frame (clamping member) 16 that is held between the two. Further, in the chassis 14, a cold cathode tube (light source) 17, a lamp clip 18 for attaching the cold cathode tube 17 to the chassis 14, and a relay responsible for relaying electrical connection at each end of the cold cathode tube 17. A connector 19 and a holder 20 that collectively covers the end of the cold cathode tube 17 group and the relay connector 19 group are provided. In the backlight device 12, the optical sheet group 15b side is a light emitting side from the cold cathode tube 17, and in this embodiment, the light emitting side (that is, the liquid crystal panel 11 side) of the optical sheet group 15b is light. It is an emission part (light emission surface) 15z (see FIGS. 3 and 4).

  The chassis 14 is made of metal and has a rectangular bottom plate and a folded outer edge (stepped portion) 21 (folded outer edge portion 21a in the short side direction) that rises from each side and is folded back into a substantially U shape to form a step with the bottom plate. And a sheet metal is formed into a shallow substantially box shape including a folded outer edge portion 21b) in the long side direction. The bottom plate of the chassis 14 has a plurality of attachment holes 22 for attaching the relay connector 19 to both ends in the long side direction. Further, as shown in FIG. 3, a fixing hole 14c is formed on the upper surface of the folded outer edge portion (stepped portion) 21b of the chassis 14, and the bezel 13, the frame 16, the chassis 14 and the like are attached by screws or the like. It can be integrated.

  A reflection sheet 23 is disposed on the inner surface side of the bottom plate of the chassis 14 (the surface side facing the cold cathode tube 17). The reflection sheet 23 is made of synthetic resin, and the surface thereof is white with excellent light reflectivity. The reflection sheet 23 is laid so as to cover almost the entire region along the inside of the bottom plate surface of the chassis 14. As shown in FIG. 3, the long side edge of the reflection sheet 23 rises so as to cover the folded outer edge (stepped portion) 21b of the chassis 14, and is fixed in a state sandwiched between the chassis 14 and the diffusion plate 15a. ing. With this reflection sheet 23, the light emitted from the cold cathode tube 17 can be reflected toward the diffusion plate 15a.

  The cold-cathode tube (light source) 17 is a linear light source having an elongated tubular shape, and in a state in which the length direction (axial direction) coincides with the long side direction of the chassis 14, a large number of them are parallel to each other. They are housed in the chassis 14 in a line-up state (that is, in a state of being arranged in parallel) (see FIG. 2). The cold cathode tube 17 is slightly lifted from the bottom plate (reflective sheet 23) of the chassis 14, and each end of the cold cathode tube 17 is fitted into the relay connector 19 so as to cover the relay connector 19. (Cover member) 20 is attached.

  The holder (cover member) 20 is made of a synthetic resin exhibiting a light-reflective white color, covers the end of the cold cathode tube 17, and has an elongated and substantially box shape extending along the short side direction of the chassis 14. As shown in FIG. 4, the holder 20 is arranged in a state of being partially overlapped with the folded outer edge portion 21a in the short side direction of the chassis 14, and forms the side wall of the backlight device 12 together with the folded outer edge portion 21a. ing. An insertion pin 24 protrudes from a surface of the holder 20 facing the folded outer edge portion 21a of the chassis 14, and the insertion pin 24 is inserted into an insertion hole 25 formed on the upper surface of the folded outer edge portion 21a of the chassis 14. Thus, the holder 20 is attached to the chassis 14.

  Further, the light emitting surface 15z side of the holder 20 is composed of two surfaces parallel to the bottom plate surface of the chassis 14, and the diffusion plate mounting surface (first surface) 20a located at the lower side has a short edge of the diffusion plate 15a. The part is placed. Further, an inclined cover 26 that inclines toward the bottom plate surface of the chassis 14 extends from the diffusion plate mounting surface (first surface) 20a. The second surface 20 b of the holder 20 is covered with a short side frame 16 a for sandwiching the liquid crystal panel 11. In FIG. 2, the short side frame 16a is not shown in order to ensure visibility on the drawing. Further, in FIG. 4, the cold cathode tube 17 is not shown for ensuring visibility on the drawing.

  The diffusion plate 15 a is configured in a rectangular shape, and among the four sides, the short side end is on the diffusion plate placement surface (first surface) 20 a of the holder 20, and the long side end is the turn of the chassis 14. It is arranged on the outer edge part (step part) 21b, and is composed of a member that diffuses and transmits light from the cold cathode tube 17. Specifically, light scattering particles are dispersed and blended into a synthetic resin plate-like member, and the linear light emitted from the cold cathode tube 17 as a linear light source (tubular light source) is diffused into a planar shape. Has a function to convert. In this embodiment, the diffusion plate 15a has a thickness of 2 mm and a total light transmittance of about 85%.

  The optical sheet group 15b is a member that changes the emission characteristics (for example, emission angle, in-plane luminance distribution, etc.) of the light emitted from the cold cathode tube 17, more specifically, the light emitted from the diffusion plate 15a. A lens sheet, a diffusion sheet, a reflective polarizing film, and the like disposed adjacent to the diffusion plate 15a from the 15a side are laminated (see FIG. 1). The optical sheet group 15b is configured in the same rectangular shape as the diffusion plate 15a, and the short side end is sandwiched between the outer edge of the diffusion plate 15a and the long side frame 16, while the long side end is the same as the diffusion plate. It is sandwiched between the outer edge of 15a and the short side frame 16a. Therefore, in this embodiment, the long side frame 16 and the short side frame 16a use the optical sheet group 15b as the light emitting surface 15z as the first holding member that holds the optical sheet group 15b from the cold cathode tube 17 side. It is comprised as a 2nd clamping member clamped from the side. Although the diffusion plate 15a is regarded as a clamping member, the chassis 14 and the holder 20 substantially support the optical sheet group 15b via the diffusion plate 15a, and the chassis 14 and the holder 20 are the first. It can be said that it constitutes a clamping member.

  In the optical sheet group 15b, the lens sheet has a configuration in which a linear convex lens (convex cylindrical lens, lenticular lens) is formed in parallel on the surface (light emitting surface) of a transparent base made of synthetic resin. The longitudinal direction of the cold cathode tube 17 and the longitudinal direction of the convex lens are arranged in parallel. The diffusion sheet has a configuration in which a diffusion layer in which light scattering particles are dispersed and mixed is bonded to the surface of a synthetic resin-made translucent substrate. The reflective polarizing film having the light emitting surface 15z (that is, disposed facing the liquid crystal panel 11) is configured to transmit part of the light emitted from the diffusion sheet and reflect the other part. The panel 11 has a function of increasing the light use efficiency to the pixels. The reflected light is reused by reflection of the reflection sheet 23 and the like.

  Further, as shown in FIGS. 3 and 4, the optical sheet group 15 b (here, the reflective polarizing film) is disposed between the long side frame 16 and the short side frame 16 a via a buffer member 70. As shown in FIG. 5, the buffer member 70 includes a piezoelectric element 72 that deforms when a voltage is applied and a sponge-like foam member 71 made of a urethane resin having a higher elastic modulus than that of the piezoelectric element 72. It has the composition which becomes.

  In this embodiment, the piezoelectric element 72 is of the piezoelectric longitudinal effect type, and as shown in FIG. 6, the thickness direction (the y-axis direction of the coordinate axes shown in the figure: here, the optical sheet group 15b and the sandwiching member 16 is used. Thus, the size of the piezoelectric element 72 (the direction in which the buffer member 70 is sandwiched) can be changed. Specifically, when the piezoelectric body 73 has a configuration in which the thickness direction (y-axis direction) is sandwiched between a pair of electrodes 74 and 75 and a voltage is applied from the power supply unit 80, FIG. Thus, the piezoelectric body 73 is deformed so as to increase the thickness direction (y-axis direction). On the other hand, when the voltage application from the power supply unit 80 is canceled, the piezoelectric body 73 is deformed so as to reduce the thickness direction (y-axis direction) as shown in FIG. The piezoelectric body 73 can be configured using lead zirconate titanate, barium titanate, lithium niobate, lithium tantalate, or the like.

  As shown in FIG. 7, the power supply unit 80 constitutes a piezoelectric element driving mechanism 100. The temperature sensor 91 disposed inside the chassis 14 as shown in FIG. 3 or the chassis 14 as shown in FIG. The voltage application to the piezoelectric element 72 is controlled on the basis of information from an inverter board (light source drive circuit) 90 disposed on the outside of the piezoelectric element 72.

Specifically, when voltage application to the piezoelectric element 72 is controlled based on temperature information from the temperature sensor 91, it is as follows.
When the temperature of the backlight device 12 changes by a predetermined value, the voltage application to the piezoelectric element 72 is canceled so that the thickness of the piezoelectric element 72 is deformed small (voltage non-application state). On the other hand, when the temperature becomes constant for a predetermined time, voltage application to the piezoelectric element 72 is performed again (voltage application state). Thereby, voltage application to the piezoelectric element 72 can be controlled in accordance with the temperature change of the backlight device 12.

On the other hand, when voltage application to the piezoelectric element 72 is controlled based on information from the light source driving circuit 90, it is as follows.
When the lighting state information is acquired from information from the light source driving circuit 90, that is, whether or not power is being supplied from the light source driving circuit 90 to the cold cathode tube 17, the lighting state of the cold cathode tube 17 changes (non- When changing from the lighting state to the lighting state, or when changing from the lighting state to the non-lighting state, the voltage application to the piezoelectric element 72 is canceled so that the thickness of the piezoelectric element 72 is reduced (voltage non-voltage). Applied state). On the other hand, when the lighting state changes and a constant lighting state (including a non-lighting state) is maintained for a predetermined time, voltage application to the piezoelectric element 72 is performed again (voltage application state). Thus, voltage application to the piezoelectric element 72 can be controlled in accordance with a change in the lighting state of the cold cathode tube 17 in the backlight device 12.

  The long side frame 16 and the short side frame 16a are frame members made of synthetic resin, and have a mounting surface on which the liquid crystal panel 11 is mounted on the side opposite to the surface that holds the optical sheet group 15b. The liquid crystal panel 11 is sandwiched between the long side frame 16 and the short side frame 16a and a bezel (third clamping member) 13 placed outside the backlight device 12, and each of the frames 16, 16a. A buffer member 60 is disposed between the liquid crystal panel 11 and the liquid crystal panel 11. The buffer member 60 has the same configuration as the foam member 71 described above.

  In the present embodiment, the cold cathode tubes 17 are accommodated in parallel in a space (light source accommodation chamber) formed between the reflection sheet 23 disposed on the inner surface side of the chassis 14 and the diffusion plate 15a. The cold cathode tube 17 used in this embodiment has a tube diameter x = 4.0 mm, a distance y = 0.8 mm between the cold cathode tube 17 and the reflection sheet 23, and a distance z = 16 between adjacent cold cathode tubes 17. 4 mm, and the distance w between the cold cathode tube 17 and the diffusion plate 15a is 2.7 mm. As described above, the backlight device 12 is thinned between the constituent members, and in particular, the distance between the cold cathode tube 17 and the diffusion plate 15a and the distance between the cold cathode tube 17 and the reflection sheet 23 are reduced. . Then, by reducing the thickness of the backlight device 12 as described above, the thickness of the liquid crystal display device 10 (that is, the thickness from the front surface of the liquid crystal panel 11 to the back surface of the backlight device 12) is 16 mm, and the thickness of the television receiver TV. That is, the thickness from the front surface cabinet Ca to the back surface of the back cabinet Cb is 34 mm, and a thin television receiver is realized.

According to the present embodiment having the above-described configuration, the following operational effects are achieved.
In the backlight device 12, a buffer member 70 is interposed between the optical sheet group 15 b (optical member 15), the long side frame 16, and the short side frame 16 a, and the buffer member 70 includes a piezoelectric element 72. Therefore, the thickness of the buffer member 70 can be changed by applying a voltage to the piezoelectric element 72.

  Specifically, the direction in which the buffer member 70 is sandwiched between the optical sheet group 15b (optical member 15) and the frames 16 and 16a in accordance with the voltage application to the piezoelectric element 72 (thickness direction: y in FIG. 5). In the axial direction, the thickness can be changed. Thus, for example, even when the optical sheet group 15b (optical member 15) expands and contracts (in the x-axis direction in FIG. 5) due to a change in the usage environment (temperature change) of the backlight device 12, the buffer member 70 If the voltage application to the piezoelectric element 72 is released to reduce the thickness of the optical sheet group 15b (optical member 15), the clamping force (pressing force) on the optical sheet group 15b (optical member 15) is reduced, and the optical sheet group 15b (optical member 15) There is no restriction on expansion and contraction. As a result, the optical sheet group 15b (optical member 15) can freely expand and contract, and the optical sheet group 15b (optical member 15) is less likely to wrinkle or bend. Is difficult to occur. On the other hand, when the usage environment (temperature, etc.) of the backlight device 12 becomes constant and the optical sheet group 15b (optical member 15) does not expand or contract, the piezoelectric element 72 is increased to increase the thickness of the buffer member 70. By applying voltage, the optical sheet group 15b (optical member 15) can be fixed with a sufficient clamping force (pressing force). As described above, according to the configuration of the present embodiment, the optical sheet group 15b (optical member 15) is securely fixed, and voltage application control to the piezoelectric element 72 is performed even when a temperature change occurs. As a result, the optical member 15 (optical sheet group 15b) is less likely to wrinkle or bend, and can emit uniform light.

  In particular, when voltage application to the piezoelectric element 72 is controlled based on information from the temperature sensor 91, that is, according to a temperature change of the backlight device 12, the thickness direction of the piezoelectric element 72 (see FIG. 6). The size of the optical sheet group 15b (optical member 15) can be freely expanded and contracted when the temperature changes, and the optical sheet group 15b (optical member 15) can be freely expanded and contracted. It becomes possible to make it difficult for wrinkles and deflections to occur. In particular, since the expansion and contraction of the optical sheet group 15b (optical member 15) is greatly influenced by the temperature change, it is preferable to control the driving of the piezoelectric element 72 based on the information from the temperature sensor 91 as described above.

  When voltage application to the piezoelectric element 72 is controlled based on information from the light source driving circuit 90, that is, according to the lighting state of the cold cathode tube 17, the thickness of the piezoelectric element 72 is changed when the lighting state of the cold cathode tube 17 changes. The size of the optical sheet group 15b (optical member 15) can be freely expanded and contracted when the lighting state is changed. It is possible to make the group 15b (optical member 15) less likely to wrinkle or bend. The expansion and contraction of the optical sheet group 15b (optical member 15) is greatly influenced by the temperature change. However, the temperature change becomes large when the lighting state of the cold cathode tube 17 changes. It is preferable to control the driving of the piezoelectric element 72 based on the above.

  Although the embodiment according to the present invention has been described above, the present invention is not limited to the embodiment described with reference to the above description and drawings. For example, the following embodiment is also included in the technical scope of the present invention. Further, various modifications other than those described below can be made without departing from the scope of the invention.

<Modification of Piezoelectric Element 72>
In the above embodiment, the piezoelectric longitudinal effect type piezoelectric body is used as the piezoelectric body of the piezoelectric element 72. However, as shown in FIG. 10, a piezoelectric lateral effect type piezoelectric body 73a may be employed. In this case, as shown in FIG. 11, the thickness (y-axis direction) decreases with voltage application, and as shown in FIG. 12, the thickness (y-axis direction) increases with voltage application cancellation.

  Therefore, even when the optical sheet group 15b (optical member 15) expands and contracts (in the x-axis direction in FIG. 5) due to changes in the usage environment (temperature change) of the backlight device 12, the thickness of the buffer member 70 is increased. If voltage is applied to the piezoelectric element 72 to reduce the thickness, the clamping force (pressing force) on the optical sheet group 15b (optical member 15) is reduced, and the optical sheet group 15b (optical member 15) expands. There is no restriction on the shrinkage. As a result, the optical sheet group 15b (optical member 15) can freely expand and contract, and the optical sheet group 15b (optical member 15) is less likely to wrinkle or bend, and can emit uniform light. . On the other hand, when the optical sheet group 15b (optical member 15) does not expand or contract, the application of voltage to the piezoelectric element 72 is canceled to increase the thickness of the buffer member 70, whereby the optical sheet group 15b (optical member). 15) can be fixed with a sufficient clamping force (pressing force).

  As described above, even when the piezoelectric lateral effect type piezoelectric body 73a is used, the optical sheet group 15b (optical member 15) is securely fixed, and even if a temperature change occurs, the optical sheet. The group 15b (optical member 15) is less likely to wrinkle or bend, and can emit uniform light.

<Plane arrangement example of buffer member 70>
As an example of a plan view design of the buffer member 70, as shown in FIG. 13, for example, a single linear buffer member 70 can be disposed on each of the four sides of the optical member 15 (optical sheet group 15b).
Alternatively, as shown in FIG. 14, a plurality of buffer members 70 may be arranged in pieces on each of the four sides of the optical member 15 (optical sheet group 15 b).

<Installation position of buffer member 70>
In the above embodiment, the buffer member 70 is provided between the long side frame 16 and the short side frame 16a and the optical sheet group 15b. However, as shown in FIG. 15, the diffusion plate 15a and the optical sheet group 15b The buffer member 70 may be disposed between them. In this case, the chassis 14 is substantially a clamping member, and has a function for clamping the optical sheet group 15b (optical member 15).

<Other variations>
Further, in the present embodiment, the following modifications are possible.
(1) Although a cold cathode tube is adopted as the light source, other discharge tubes such as a hot cathode tube can also be used.
(2) Although the diffusion plate 15a is arranged on the folded outer edge portion (stepped portion) 21b of the chassis 14 and the first surface 20a of the holder 20, the thickness is larger than the optical sheet group 15b, and the optical As long as the sheet group 15b is a member that can be sandwiched between the frames 16 and 16a, the member disposed on the folded outer edge (stepped portion) 21b of the chassis 14 and the first surface 20a of the holder 20 is the diffusion plate. It is not limited to 15a.
(3) The light emitting side surface of the reflective polarizing film is the light emitting surface (light emitting portion) 15z of the backlight device (illuminating device) 12, but the light emitting portion is a member facing the irradiation target (liquid crystal panel). For example, when an optical sheet such as a diffusion sheet is disposed on the light exit side, the light exit side of the optical sheet serves as a light exit portion, and the optical sheet serves as the buffer member 70. Between the frames 16 and 16a.

The disassembled perspective view which shows schematic structure of the television receiver which concerns on embodiment of this invention. The disassembled perspective view which shows schematic structure of the liquid crystal display device with which the television receiver of FIG. 1 is provided. Sectional drawing which shows the cross-sectional structure along the short side direction of the liquid crystal display device of FIG. Sectional drawing which shows the cross-sectional structure along the long side direction of the liquid crystal display device of FIG. Sectional drawing which expands and shows the buffer member provided in the illuminating device. Explanatory drawing which shows the structure of the piezoelectric element with which the buffer member was equipped. The block diagram which shows the structure of a piezoelectric element drive mechanism. Explanatory drawing which shows the thickness increase aspect of a piezoelectric element. Explanatory drawing which shows the thickness reduction | decrease aspect of a piezoelectric element. Explanatory drawing which shows typically the structure of the modification of a piezoelectric element. Explanatory drawing which shows the thickness reduction | decrease aspect of the piezoelectric element of FIG. Explanatory drawing which shows the thickness increase aspect of the piezoelectric element of FIG. An explanatory view showing an example of plane arrangement of a buffer member. Explanatory drawing which shows the modification of the planar arrangement | positioning of a buffer member. Explanatory drawing which shows the modification of the installation position of a buffer member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device (display device), 11 ... Liquid crystal panel (display panel), 12 ... Backlight device (illumination device), 13 ... Bezel (3rd clamping member), 14 ... Chassis (1st clamping member), 15 ... optical member, 15a ... diffusion plate (optical member), 15b ... optical sheet group (optical member), 15z ... light emission surface (light emission part), 16 ... long side frame (second clamping member), 16a ... short side Frame (second clamping member), 17 ... Cold cathode tube (light source), 20 ... Cover member (first clamping member), 70 ... Buffer member, 71 ... Foam member, 72 ... Piezoelectric element, 73 ... Piezoelectric body, 74, 75 ... Electrode, TV ... TV receiver

Claims (9)

An illumination device including a light emitting unit that emits light,
A light source, and an optical member disposed closer to the light emitting part than the light source,
The optical member is sandwiched between a pair of sandwiching members,
The clamping member includes a first clamping member that clamps the optical member from the light source side, and a second clamping member that clamps the optical member from the side opposite to the light source side,
A buffer member is interposed between at least one of the optical member and the first clamping member or between the optical member and the second clamping member,
The said buffer member comprises a piezoelectric element, The illuminating device characterized by the above-mentioned.   The lighting device according to claim 1, wherein the piezoelectric element is deformed in a direction in which the piezoelectric element is sandwiched between the optical member and the sandwiching member in accordance with voltage application to the piezoelectric element. A power supply unit for applying a voltage to the piezoelectric element;
The lighting device according to claim 1, wherein the power source unit controls voltage application to the piezoelectric element in accordance with a temperature change of the lighting device.   The power supply unit applies a voltage to the piezoelectric element so that the piezoelectric element is deformed to a small extent in a direction in which the piezoelectric element is sandwiched between the optical member and the sandwiching member when the temperature of the lighting device changes. The lighting device according to claim 1, wherein the lighting device is controlled. A power supply unit for applying a voltage to the piezoelectric element;
The power supply unit switches a voltage application state to the piezoelectric element when the light source changes from a non-lighting state to a lighting state, or when the light source changes from a lighting state to a non-lighting state. The lighting device according to claim 2.   2. The buffer member according to claim 1, wherein the piezoelectric element is disposed on the holding member side, and a foam member having a higher elastic modulus than the piezoelectric element is disposed on the optical member side. Item 6. The lighting device according to any one of Items 5. The lighting device according to any one of claims 1 to 6,
And a display panel that performs display using light from the lighting device.   The display device according to claim 7, wherein the display panel is a liquid crystal panel using liquid crystal.   A television receiver comprising the display device according to claim 7 or 8.

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