JP2008040068A - Flat display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat display device having high cooling performance of a plasma display panel (PDP), and compact and simple structure. <P>SOLUTION: The PDP 1 is adhered to a chassis member 2 for holding the PDP 1 by a heat conductive adhesive member 3. The adhesive member 3 is formed on the PDP 1 in a plurality of stripes 30 with prescribed width and cooling air is ventilated through gap parts 4 between the stripes 30. When it is defined that the width of the stripe 30 of the adhesive member 3 is A and the width of the gap part 4 is B, a gap ratio B/(A+B) is preferably set to ≥0.5. Further, the flat display device is provided with a pump 8 for supplying cooling air to be ventilated to the gap parts 4 and conductors 5, 7, etc., for guiding the cooling air supplied from the pump 8 to the opening parts of the gap parts 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flat display device having a self-luminous display panel, and more particularly to a cooling technique for a display panel that generates heat.

  In recent years, with the development of digital technology, large-screen and thin display devices are rapidly spreading. One of them is a flat display device using a self-luminous plasma display panel. In a large-screen display device, the number of pixels is increased in order to display a high-definition image. In order to obtain sufficient image brightness, the amount of light emitted from each pixel is increased. This increases the amount of heat generated, leading to an increase in the temperature of the entire display panel. The rise in temperature changes the light emission luminance of the phosphor, which causes degradation of image quality. Furthermore, in an image where the brightness is high only on a part of the screen, the plasma discharge concentrates on that part, causing a local temperature rise of the display panel, resulting in damage to the glass substrate constituting the panel There is also.

  The following proposals have been made as a technique for cooling the heat generated by a display device such as a plasma display panel. Patent Document 1 aims at a display device excellent in high heat dissipation characteristics and repairability (the panel and the holding plate that have been fixed once can be easily separated), and the heat conduction of the display panel and the heat dissipation holding plate is made of an adhesive. A configuration in which a member is applied in a plurality of lines and bonded is disclosed. It is stated that by applying the adhesive in a line shape, it is difficult for bubbles to enter the joining surface, and the distance at which the joining surface is sequentially separated is short, so that it can be more easily peeled off.

  Patent Document 2 measures (or calculates) the surface temperature distribution of a panel with the problem that when a still image with a large gradation difference is displayed on the display panel, a temperature difference occurs on the panel and the light emission luminance partially changes. And the structure which controls the rotation speed of a some fan (cooling device group) so that it may become reference | standard temperature is disclosed. As a result, it is stated that white balance adjustment can be realized with a constant surface temperature of the panel and little change in luminance.

  Furthermore, a water-cooling method for circulating the refrigerant liquid and a method for cooling with a heat-radiating fin and a heat-dissipating fan by connecting a heat pipe to the heat-radiating plate have been proposed.

JP 2004-333904 A JP-A-10-232647

  In the cooling method described in Patent Document 1, heat generated from the panel is transferred to the holding plate, and natural heat dissipation is performed from the holding plate. In general, the heat conduction characteristics of the adhesive are not good, so that a sufficient heat dissipation effect may not be obtained. In addition, although the panel is easily peeled by forming the adhesive in a line shape, a decrease in the heat transfer amount is unavoidable because the bonding area is reduced, and thus the cooling performance is limited.

  Further, the cooling method described in Patent Document 2 can be expected to increase the cooling performance and keep the panel surface temperature constant. However, as a device configuration, it is necessary to arrange a plurality of temperature measuring devices and cooling fans finely, which leads to an increase in size, complexity and cost of the device. This problem is the same in the case of the water cooling method or the heat pipe combined method.

  An object of the present invention is to provide a flat display device having a high cooling performance and a small and simple structure.

  In order to solve the above-described problems, a flat display device using a plasma display panel according to the present invention includes a chassis member that holds the plasma display panel and has a heat dissipation function, and a thermal conductive material that bonds the plasma display panel and the chassis member. An adhesive member, and the adhesive member is formed in a plurality of stripes having a predetermined width on the plasma display panel, and the cooling air is blown through the gaps between the stripes. Here, when the width of the stripe of the adhesive member is A and the width of the gap is B, the porosity B / (A + B) is preferably 0.5 or more.

  In addition, a pump that supplies cooling air to be passed through the gap and a conduit that guides the cooling air supplied from the pump to the opening of the gap are provided. Further, the entire surface of the plasma display panel is divided into a plurality of regions along the stripe of the adhesive member, and the flow rate of the cooling air passing through the gaps in each region is changed according to the luminance level of the video signal.

  The pressure-sensitive adhesive member is preferably formed by applying a hot melt adhesive having fluidity when heated at a high temperature in a stripe shape.

  According to the present invention, a flat display device having a high cooling performance and a small and simple structure can be realized.

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

  FIG. 1 is a side view conceptually showing an embodiment of a plasma display panel (hereinafter abbreviated as PDP) module used in a flat display device according to the present invention. The PDP 1 includes a light-emitting element unit 11 that emits ultraviolet rays by discharge and irradiates a phosphor to emit light, and a front glass substrate 12 and a back glass substrate 13 that sandwich the light emitter element unit 11 from the front and rear.

  The PDP 1 is held by a chassis member 2 having a heat dissipation function, and both are bonded by an adhesive member 3. On the back surface of the chassis member 2, circuit components 21 for driving image signal processing and the PDP 1 are mounted. The chassis member 2 uses a material such as aluminum having good thermal conductivity to improve heat dissipation characteristics. The adhesive member 3 transfers heat generated from the PDP 1 to the chassis member 2 and dissipates heat from the chassis member 2.

  As will be described later, in the PDP module of the present embodiment, the adhesive member 3 is not bonded to the entire surface between the PDP 1 and the chassis member 2, but is formed in a stripe shape having a predetermined gap to bond them together. Yes. The pressure-sensitive adhesive material is formed by applying, for example, a hot melt adhesive having fluidity at a high temperature. Then, a cooling air is poured into the gap between the stripes so that heat generated from the PDP 1 and the circuit components 21 is directly radiated to the outside by the cooling air.

  FIG. 2 is an embodiment of the flat display device 9 according to the present invention, and conceptually shows a configuration in which a cooling mechanism is attached to the PDP module of FIG. (A) is a front view, (b) is a plan view. In (a), in order to make the structure of the adhesive member 3 easy to understand, a part of the PDP 1 and the chassis member 2 is removed.

  The pressure-sensitive adhesive member 3 that bonds the PDP 1 (glass substrate 13) and the chassis member 2 is a heat conductive adhesive such as a hot-melt adhesive, and is formed in a stripe 30 shape in the vertical direction of the PDP module. The hot melt adhesive is heated to a high temperature and applied as a fluidized state to the glass plate 13 of the PDP 1 in a plurality of stripes. The chassis member 2 is pressed against this to bond the PDP 1 and the chassis member 2 together. The applied adhesive loses fluidity and solidifies at low temperatures, and has the property of maintaining the adhesive force.

  The shape of the adhesive member 3 is, for example, A = 6 mm, B = 6 mm, and H = 1 mm, where A is the width of the stripe 30, B is the gap, and H is the thickness. The width A of the stripe 30 is determined so that necessary adhesive strength (holding strength by the chassis member 2) can be obtained. Between the adjacent stripes 30, a cylindrical gap 4 having a substantially rectangular cross section (B × H) and penetrating in the vertical direction of the PDP 1 is formed. The cylindrical gap 4 has openings 41 and 42 at the upper and lower ends, and cools the PDP 1 by passing cooling air (cooling air) through it.

  The cooling air is supplied by a pump 8, a conduit 7, a header portion 6, and an introduction path (conduit) 5 installed below the PDP module. The air sucked by the pump 8 is once sent to the header section 6, where it is divided and injected from the respective introduction paths 5 into the lower end openings 42 of the respective gap sections 4. When the cooling air moves upward through the gap 4, it absorbs heat from the wall surface of the PDP 1 and the chassis member 2 and is released from the upper end opening 41 to the outside of the device.

  Although the cooling efficiency in this configuration depends on the flow rate of air, for example, when air is introduced at a flow rate of 0.3 m / sec, there is an effect of reducing the surface temperature of the PDP 1 by about 10 ° C., and excellent cooling performance is obtained. . In this embodiment, since the gap portion 4 is formed in the portion of the adhesive member 3 inside the PDP module for cooling, the external shape of the PDP module maintains the conventional size and supplies cooling air. Since pumps and conduits can be realized with a simple configuration, it is possible to reduce the size of the equipment.

  In this embodiment, the stripe (that is, the gap) formed in the PDP module is in the vertical direction, and air is introduced from below. Thereby, the heat-received air can move and circulate along the direction of natural convection. When forced circulation is performed by a pump or the like, the direction of the stripe can be other than the vertical direction (for example, the horizontal direction). Further, the stripes may be formed intermittently rather than continuously.

  As described above, the cooling mechanism of this embodiment has excellent cooling performance. The reason will be considered below. FIGS. 3A and 3B are diagrams schematically illustrating the cooling operation in the present embodiment, in which FIG. 3A is a case of whole surface bonding for comparison (conventional example), and FIG. 3B is a stripe bonding of the present embodiment. It is.

  In the conventional example of FIG. 3A, the heat conductive adhesive 3 is formed on the entire surface of the PDP 1 to bond the chassis member 2, and heat is radiated by flowing cooling air over the surface of the chassis member 2.

  Heat is transferred from the PDP 1 having the heat generation temperature Th to the chassis member 2 through the adhesive 3 ′, and is further radiated from the chassis member 2 having the temperature Tc by the cooling air having the temperature Ta. The amount of heat release in this case is almost governed by the heat transfer coefficient hs of the adhesive 3 and the heat transfer coefficient ha by the cooling air. Considering heat transfer per unit area of the bonding surface, the heat transfer coefficient hs depends on the thermal conductivity and thickness H of the adhesive, and the heat transfer coefficient ha depends on the wind speed of the cooling air. The chassis member 2 has a sufficiently small thermal resistance and is ignored.

In this case, the amount of heat W0 (1) moving from the PDP 1 to the chassis member 2 is
W0 (1) = hs · (Th−Tc)
The amount of heat W0 (2) radiated from the chassis member 2 to the cooling air is
W0 (2) = ha · (Tc−Ta)
Since these are equal in steady state, if this is W0,
W0 = {1 / (1 / hs + 1 / ha)}. (Th-Ta)
Therefore, if the total heat transfer coefficient (heat dissipation coefficient) is h0,
h0 = 1 / (1 / hs + 1 / ha) (1)
FIG. 3B shows the case of this embodiment. The adhesive (adhesive member) 3 (30) has a stripe shape with a width A and a gap portion 4 with a width B, and cooling air is poured into the gap portion 4. Here, the ratio occupied by the gap 4 is assumed to be the gap ratio k = B / (A + B). The thermal conductivity of the adhesive 3 and the wind speed of the cooling air are the same conditions as in the above (a).

In this case, there are two heat dissipation paths: a path that directly radiates heat from the PDP 1 to the cooling air in the gap 4, and a path that radiates heat from the chassis member 2 to the cooling air in the gap 4 via the adhesive 3. Since the heat radiation area W1 is proportional to the porosity k,
W1 = k · ha · (Th-Ta)
The heat radiation amount W2 by the latter is such that the adhesion area is proportional to (1-k) and the heat radiation area is proportional to k.
W2 = {1 / (1 / (1-k) .hs + 1 / k.ha)}. (Th-Ta)
When these are added,
W1 + W2
= {K.ha + 1 / (1 / (1-k) .hs + 1 / k.ha)}. (Th-Ta)
Therefore, if the total heat transfer coefficient (heat dissipation coefficient) is h1,
h1 = k.ha + 1 / (1 / (1-k) .hs + 1 / k.ha) (2)

  FIG. 4 is a diagram in which the above equations (1) and (2) are calculated and the heat dissipation coefficient of the present embodiment is compared with the conventional one. The vertical axis represents the values of h0 and h1, the horizontal axis represents the ratio ha / hs between the cooling air and the heat transfer coefficient of the adhesive, and the porosity k is a parameter. As can be seen from the figure, the heat radiation performance is increased as compared with the prior art by providing the gap. If the heat transfer coefficient ratio ha / hs = 1, the porosity k is 0.3 or more, which is improved over the prior art. Even if the ratio ha / hs <1, the porosity k is set to 0. If it is 5 or more, it will always exceed the conventional level. This is because the direct cooling of the PDP 1 by the gap 4 (that is, the path of the heat radiation amount W1) contributes greatly.

  In this embodiment, since the adhesive member 3 holds the PDP 1, its width A needs to be set so that sufficient holding strength can be obtained. Therefore, if the porosity k is about 0.5 (for example, about A = B = 6 mm), both the cooling performance and the holding strength can be satisfied. Further, the thickness H of the adhesive member 3 is preferably as small as possible in order to reduce the thermal resistance of the path of the heat radiation amount W2. On the other hand, considering that heat transfer to the cooling air flowing through the gap is efficiently performed, the thickness H is suitably several mm or less (for example, about 1 mm).

  Furthermore, the present embodiment is characterized in that a hot-melt adhesive is used as the pressure-sensitive adhesive material 3. FIG. 5 shows a comparison of the temperature dependence of the shear strength between a hot melt material and a general adhesive (adhesive tape). A conventional adhesive (adhesive tape) has a small temperature dependency of strength. On the other hand, the hot melt material is in a fluid state when heated to a high temperature, and has a property of losing fluidity and solidifying at a low temperature. For example, the strength changes about 30 times at normal temperature (20 ° C.) and high temperature (100 ° C.).

  A conventional PDP module using an adhesive cannot be easily disassembled. On the other hand, in this embodiment, the use of a hot melt material facilitates adhesion and disassembly. That is, when the PDP and the chassis member are bonded, the PDP module is heated to a high temperature, and even when the PDP module is disassembled, the hot melt material is softened by heating to a high temperature, so that the PDP and the chassis member can be easily separated. During the PDP operation, the panel temperature, that is, the hot melt material that is an adhesive member also rises in temperature, but can be efficiently cooled by the cooling mechanism of this embodiment described above. Therefore, the adhesive strength does not decrease during the PDP operation.

  FIG. 6 shows another embodiment of the flat display device 9 according to the present invention, where (a) shows a front view and (b) shows a plan view. Also in this embodiment, the PDP module has the same configuration as that shown in FIGS. 1 and 2, and the adhesive member 3 is formed in a stripe 30 shape in the vertical direction of the PDP module. The entire surface of the PDP 1 is divided into a plurality of regions 1 a to 1 d along the stripe 30, and the flow rate of the cooling air flowing through the gap 4 can be controlled in each region. That is, pumps 8a to 8d, conduits 7a to 7d, and header portions 6a to 6d are provided in each region, and the amount of cooling air supplied from each pump 8a to 8d is set according to the luminance level of the video signal in each region. Change. In this configuration, each pump and each conduit can be shared, and for example, a throttle valve can be provided in each header portion to control the flow rate. As a result, the entire screen can be maintained in a substantially uniform temperature state, and a good screen with little change in luminance is realized.

  Also in this embodiment, since cooling air is poured into the gap portion 4 inside the PDP module to cool it, the cooling performance is excellent, and the outer shape of the PDP module can be maintained at the conventional size. In addition, a pump and a conduit for supplying cooling air can be realized with a simple configuration, and there are few restrictions on the installation location of the pump, so that the equipment can be downsized.

  In each of the above embodiments, a plasma display panel (PDP) has been described as an example of the display element. However, the present invention is not limited to this, and can be widely applied to flat display devices having a self-luminous display panel.

The side view which shows one Example of the PDP module used with the flat type display apparatus by this invention. The figure which shows one Example of the flat type display apparatus by this invention. The figure which illustrates typically the cooling operation in a present Example. The figure which compared the heat dissipation coefficient in a present Example with the past. The figure which compared the temperature dependence of the shear strength of a hot-melt material and an adhesive tape. The figure which shows the other Example of the flat type display apparatus by this invention.

Explanation of symbols

1 ... Plasma Display Panel (PDP)
2 ... Chassis member 3 ... Adhesive member 4 ... Gap (ventilation path)
DESCRIPTION OF SYMBOLS 5 ... Introduction path 6 ... Header part 7 ... Conduit 8 ... Pump 9 ... Flat panel display device 11 ... Light-emitting element part 12, 13 ... Glass substrate 21 ... Circuit component 30 ... Stripe-like adhesive member 41, 42 ... Opening part.

Claims (5)

In a flat display device using a plasma display panel,
A chassis member that holds the plasma display panel and has a heat dissipation function;
A heat conductive adhesive member for bonding the plasma display panel and the chassis member;
The flat display device, wherein the adhesive member is formed in a plurality of stripes having a predetermined width on the plasma display panel, and cooling air is blown through gaps between the stripes. The flat display device according to claim 1,
A flat panel display device, wherein the width of the stripe of the adhesive member is A and the width of the gap is B, the porosity B / (A + B) is 0.5 or more. The flat display device according to claim 1 or 2,
A pump for supplying cooling air to be passed through the gap;
A flat display device comprising a conduit for guiding cooling air supplied from the pump to the opening of the gap. The flat display device according to claim 3,
Dividing the entire surface of the plasma display panel into a plurality of regions along the stripe of the adhesive member, and changing a flow rate of cooling air flowing through the gap in each region in accordance with a luminance level of a video signal. A flat-panel display device. The flat display device according to claim 1 or 2,
The flat display device, wherein the pressure-sensitive adhesive member is formed by applying a hot melt adhesive having fluidity when heated at a high temperature in a stripe shape.

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