JP7598263B2 - Display device - Google Patents

Description

This disclosure relates to a display device.

For example, in a display device equipped with a display panel such as an organic EL panel, the characteristics of the display panel may change due to an increase in temperature of the display panel, resulting in a decrease in the display quality of the display device. For this reason, in the display device of Patent Document 1, a back cover is attached to the rear surface of the display panel, and the back cover covers almost the entire rear surface of the display panel.

In the display device of Patent Document 1, a first circuit board that controls the display of the display panel is disposed on the rear end side of the back cover. A second circuit board is connected between the display panel and the first circuit board, and the second circuit board has a drive IC for driving the display panel. The drive IC, which is a heat source, is in thermal contact with a support frame that acts as a heat dissipation member.

WO2020/017210 publication

However, sometimes display panels are delivered by panel manufacturers with the first circuit board already attached to the rear surface of the display panel. In such cases, when the display device is assembled, the back cover ends up being positioned on the opposite side of the display panel's edge from the first circuit board on the rear surface of the display panel, and the heat transferred from the driving IC, which is a heat source, to the periphery of the first circuit board cannot be sufficiently dissipated. As a result, the temperature difference between the edge side and the rest of the display panel becomes large, which causes noticeable unevenness in the brightness of the display panel and leads to a problem of a deterioration in the display quality of the display device.

In view of the above problems, the present disclosure aims to reduce the temperature gradient near the heat source-substrate boundary located on the back surface of the display panel, thereby making the brightness unevenness of the display panel less noticeable and improving the display quality of the display device.

A display device according to one aspect of the present disclosure includes a display panel for displaying an image, a first circuit board disposed on the edge side of the rear surface of the display panel, a second circuit board having a heat source located closer to the edge side of the display panel than the first circuit board, a heat sink disposed at a position different from the position on the rear surface of the display panel on which the first circuit board and the second circuit board are disposed, and an adhesive layer provided between the rear surface of the display panel and a part of the heat sink, and is characterized in that the occupancy rate of the adhesive layer between the rear surface of the display panel and the heat sink decreases in the direction toward the second circuit board.

As described above, the present disclosure can reduce the temperature gradient near the heat source-substrate boundary located on the back surface of the display panel, making uneven brightness on the display panel less noticeable and improving the display quality of the display device.

FIG. 1 is a front view of a display device according to a first embodiment of the present disclosure. FIG. 2 is a front view illustrating a schematic diagram of an adhesive layer provided in the display device according to the first embodiment of the present disclosure. FIG. 3 is an enlarged view of part A in FIG. FIG. 4 is an enlarged cross-sectional view taken along line BB in FIG. FIG. 5 is an enlarged cross-sectional view taken along line CC in FIG. FIG. 6 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel of the display device of the reference example. FIG. 7 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel of the display device in the first embodiment of the present disclosure. FIG. 8 is a diagram showing temperature changes in a vertical cross section of the central portion of the left and right of the display panel of the display device according to the first embodiment of the present disclosure. FIG. 9 is a diagram showing the vicinity where the occupancy rate of the adhesive layer changes. FIG. 10 is a front view illustrating a modified example of the adhesive layer provided in the first embodiment of the present disclosure. FIG. 11 is a front view illustrating a schematic diagram of an adhesive layer provided in the second embodiment of the present disclosure. FIG. 12 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel of the display device according to the second embodiment of the present disclosure. FIG. 13 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel of the display device according to the second embodiment of the present disclosure.

Below, a preferred embodiment of the present disclosure will be described in detail with reference to the drawings. As shown in the drawings, one side of the display device 10 in the width direction will be referred to as the left side, the other side of the display device 10 in the width direction will be referred to as the right side, one side of the display device 10 in the height direction will be referred to as the upper side, and the other side of the display device 10 in the height direction will be referred to as the lower side. Note that the present embodiment described below does not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the present embodiment are necessarily essential as a solution for the present disclosure.

[First embodiment]
The display device 10 according to the first embodiment includes a display panel 12, a first circuit board, a second circuit board, a heat sink 40, and an adhesive layer 50. First, the overall configuration of the display device 10 will be described.

1 is a front view of a display device 10 according to a first embodiment of the present disclosure. As shown in FIG. 1, the display device 10 according to the first embodiment of the present disclosure is incorporated as a display panel module in, for example, a television receiver, a monitor display, or other equipment. The display device 10 includes a rectangular display panel 12 that displays an image, and the display panel 12 extends in the left-right direction. The display panel 12 is a self-luminous display panel, specifically, an organic EL panel using organic light-emitting diode elements. In other words, the display device 10 is a display panel module (OLED module) that includes an organic EL panel. The display panel 12, which is an organic EL panel, includes an EL substrate, a CF substrate (glass substrate) on which a color filter is formed, and a resin layer disposed between the EL substrate and the CF substrate, but detailed illustration and description of these elements are omitted.

The display device 10 has a rectangular frame 14 that surrounds and holds the display panel 12, and the frame 14 is made of a metal with high thermal conductivity, such as aluminum or iron.

As shown in FIG. 1, a source board 24 for controlling the display of the display panel 12 is disposed as a first circuit board on the end side of the rear surface of the display panel 12. The source board 24 extends in the left-right direction and is joined to the rear surface of the display panel 12 by a fixing member (joint member) 26 such as double-sided tape. The source board 24 is a printed circuit board on which electronic components (not shown) such as capacitors, resistors, and diodes are mounted.

As shown in FIG. 1, a plurality of flexible substrates 28 are arranged at intervals in the left-right direction on the rear side of the display panel 12 as a second circuit substrate. As shown in FIG. 5, the flexible substrates 28 are located closer to the end of the display panel 12 than the first circuit substrate. Each flexible substrate 28 is a connection substrate that connects the display panel 12 and the source substrate 24. A first connection terminal (not shown) for connecting to the display panel 12 is formed on one end of each flexible substrate 28. A second connection terminal (not shown) for connecting to the source substrate 24 is formed on the other end of each flexible substrate 28. Each flexible substrate 28 has a source driver 30 for driving the display panel 12. Each source driver 30 is located closer to the bottom side (lower end side) of the display panel 12 than the source substrate 24, and supplies a drive signal for driving the display panel 12 to the display panel 12. Each source driver 30 becomes a heat source during operation of the display device 10. The plurality of source drivers 30 are arranged at intervals in the left-right direction (width direction). Each source driver 30, which is a heat source, transfers heat to the source substrate 24.

A heat insulating member 32 is provided between the rear surface of the display panel 12 and each source driver 30. The heat insulating members 32 are arranged at intervals in the left-right direction, similar to the source drivers 30. Each heat insulating member 32 is made of a porous material, such as highly expanded silicone foam or polyurethane foam.

Here, since the second circuit board has a source driver 30, it becomes a heat source, and the heat of the source driver 30 is transferred to the source substrate 24 and then to the display panel 12. In the area where the source driver 30 and the source substrate 24 are not provided on the back side of the display panel 12, the heat is dissipated by the heat sink 40. This causes a large temperature gradient between the surface of the display panel 12 where the source driver 30 and the source substrate 24 are provided and the surface of the display panel 12 where the heat sink 40 is provided, resulting in a problem of noticeable brightness unevenness. Therefore, by providing an adhesive layer 50 provided between the back side of the display panel 12 and a part of the heat sink 40, and by decreasing the occupancy rate of the adhesive layer 50 toward the second circuit board, the temperature of the entire display panel 12 is uniformed, and the brightness unevenness of the display panel 12 is made less noticeable, thereby improving the display quality of the display device. The display device 10 according to the first embodiment will be described in detail below.

Figure 2 is a front view showing a schematic of the adhesive layer 50 provided in the display device 10 according to the first embodiment of the present disclosure. The adhesive layer 50 shown in Figure 2 is provided on the rear surface of the display panel 12 and part of the heat sink 40 as shown in Figure 3-5. As shown in Figure 3-5, the occupancy rate of the adhesive layer 50 between the rear surface of the display panel 12 and the heat sink 40 is characterized by decreasing in the direction in which it is arranged on the second circuit board.

As shown in FIG. 3, there are some areas where the adhesive layer 50 extends to the vicinity of the source substrate 24, and some areas where it does not extend. In addition, the occupancy rate of the adhesive layer 50 on the rear surface of the display panel 12 decreases toward the flexible substrate 28.

The details are explained using cross-sectional views. FIG. 4 is an enlarged cross-sectional view taken along line B-B in FIG. 3. FIG. 5 is an enlarged cross-sectional view taken along line C-C in FIG. 3. In FIG. 4, the adhesive layer 50 extends toward the flexible substrate 28 (second circuit substrate) to the vicinity of the source substrate 24 (first circuit substrate), but in FIG. 5, the adhesive layer 50 does not extend toward the flexible substrate 28 (second circuit substrate) to the vicinity of the source substrate 24 (first circuit substrate). In other words, a non-adhesive layer area S exists between the display panel 12 and the heat sink 40. In this way, the occupancy rate of the adhesive layer 50 between the rear surface of the display panel 12 and the heat sink 40 decreases toward the direction of the second circuit substrate.

In the area where the adhesive layer 50 and the heat sink 40 are provided, the heat of the source substrate 24 transmitted from the source driver 30 is easily dissipated by the heat sink 40, and the temperature of the surface of the display panel 12 becomes low, but in the area where the adhesive layer 50 and the heat sink 40 are not provided, the heat cannot be dissipated by the heat sink 40, and the temperature of the surface of the display panel 12 becomes high. Therefore, the temperature difference of the surface of the display panel 12 between the area where the heat sink 40 is provided and the area where the heat sink 40 is not provided becomes large.

Therefore, by providing a non-adhesive layer area S between the display panel 12 and the heat sink 40 and reducing the occupancy rate of the adhesive layer 50 toward the second circuit board, the non-adhesive layer area S can reduce heat dissipation from the heat sink 40 even in the area where the heat sink 40 is provided, and the temperature difference on the surface of the display panel 12 between the area where the heat sink 40 is provided and the area where the heat sink 40 is not provided can be reduced. In this way, the display device 10 according to the first embodiment efficiently equalizes the temperature of the entire display panel 12, making luminance unevenness in the display panel 12 less noticeable, thereby further improving the display quality of the display device.

As shown in FIG. 2, it is preferable that the adhesive layer 50 has a plurality of protrusions 51 on the second circuit board side. In this way, it is possible to efficiently equalize the temperature of the entire display panel 12, make the brightness unevenness of the display panel 12 less noticeable, and further improve the display quality of the display device. Furthermore, the length L of the protrusions 51 shown in FIG. 2 is preferably 1 cm to 10 cm, and more preferably 3 cm to 7 cm. If it is less than 1 cm, the non-adhesive layer area S becomes small, and the effect of equalizing the temperature of the entire display panel 12 tends to be small. On the other hand, if it is more than 10 cm, the adhesion with the heat sink 40 becomes weak, and it tends to be difficult to sufficiently attach the heat sink 40 to the display panel 12.

Conceptually, it is also possible to vary the thickness of the adhesive layer 50 in the vertical direction of the display panel 12, but preparing an adhesive layer 50 with a varying thickness is difficult in manufacturing. Therefore, according to the display device 10 of the first embodiment, the occupancy rate of the adhesive layer is reduced in the direction toward the second circuit board, so that the temperature gradient on the surface of the display panel 12 can be reduced and manufacturing can be facilitated.

The adhesive layer 50 is preferably an adhesive tape. This makes it easy to attach the display panel 12 and the heat sink 40.

A thermally conductive material may be mixed into the adhesive layer 50. The amount of the thermally conductive material mixed into the adhesive layer 50 may be greater on the upper surface side of the display panel 12. In this way, the temperature gradient can be further reduced even in the area where the heat sink 40 is provided.

The adhesive layer 50 may be a printed material, as described below, instead of an adhesive tape. In such a case, the adhesive layer 50 may be formed by screen printing or the like.

Figure 6 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel 12 of the display device of the reference example. The configuration of the display device of the reference example of Figure 6 does not have the protrusions 51 of the adhesive layer 50 as shown in Figure 2, and does not have the non-adhesive layer region S as shown in Figure 5. In addition, the cross-sectional views of the B-B line and the C-C line in Figure 3 are both configured as shown in Figure 4, and the adhesive layer is present up to the vicinity of the source substrate 24. In addition, Figure 7 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel 12 of the display device 10 in the first embodiment of the present disclosure.

As shown in FIG. 6, the display device of the reference example does not have a non-adhesive layer area S, so the heat transmitted from the source driver 30 to the source substrate 24 (first circuit substrate) is dissipated steeply from the edge of the heat sink, and it can be seen that the temperature gradient on the surface on the bottom side of the display panel 12 in the circled area is large.

On the other hand, as shown in FIG. 7, in the display device 10 according to the first embodiment of the present disclosure, the heat transferred from the source driver 30 to the source substrate 24 (first circuit substrate) can be dissipated slowly, and it can be seen that the temperature gradient on the surface on the bottom side of the display panel 12 in the circled portion is small.

Figure 8 is a diagram showing the temperature change in a vertical cross section of the left-right center of the display panel 12 of the display device 10 in the first embodiment of the present disclosure. Figure 9 is a diagram showing the vicinity where the occupancy rate of the adhesive layer 50 changes. That is, it is a diagram showing the temperature change from vertical coordinates -0.35 to -0.25 m in Figure 8. The solid line shows the temperature change of the display panel 12 of the display device 10 according to the first embodiment. Meanwhile, the dotted line shows the temperature change of the display panel of the display device of the reference example.

In FIG. 8, the source driver 30 is located on the rear surface of the display panel 12 at the coordinate with the highest temperature. The temperature decreases from the source driver 30 toward the upper surface of the display panel 12. As shown in FIG. 8 and FIG. 9, it can be seen that in the display panel 12 of the display device of the reference example, the temperature change is large from the source driver 30 toward the upper surface of the display panel 12. On the other hand, it can be seen that in the display panel 12 of the display device 10 of the first embodiment, the temperature change is small from the source driver 30 toward the upper surface of the display panel 12.

In this way, the display device 10 in the first embodiment of the present disclosure achieves uniform heating of the entire display panel 12, making uneven brightness of the display panel 12 less noticeable, thereby improving the display quality of the display device.

Figure 10 is a front view showing a schematic diagram of a modified example of the adhesive layer 50 provided in the first embodiment of the present disclosure. As shown in Figure 10, the tips of the protrusions 51 of the adhesive layer 52 are preferably rounded. This makes it difficult for the display panel 12 and the heat sink 40 to peel off, achieves uniform heating of the entire display panel 12, and makes uneven brightness of the display panel 12 less noticeable, thereby improving the display quality of the display device.

The second circuit board may be disposed on the bottom side of the display panel 12. Heat is more likely to be transferred to the top side of the display panel 12, but because air convection is not well developed on the bottom side of the display panel 12, heat transfer is predominantly due to thermal conduction. Even in this case, the ratio of the adhesive layer 52 to the non-adhesive layer area S gradually changes, so that the thermal conductivity also gradually changes, achieving uniform heating of the entire display panel 12, making uneven brightness of the display panel 12 less noticeable, and improving the display quality of the display device.

As described above, the display device 10 in the first embodiment of the present disclosure achieves uniform heating of the entire display panel 12, making uneven brightness of the display panel 12 less noticeable, thereby improving the display quality of the display device.

[Second embodiment]
Next, the second embodiment will be described. Fig. 11 is a front view showing a schematic diagram of the adhesive layer 53 provided in the second embodiment of the present disclosure. As shown in Fig. 11, the adhesive layer 53 has an adhesive layer main body 54 and dots 55, and the dots 55 are provided so as to become smaller toward the second circuit board side. The second embodiment is characterized in that the adhesive layer 53 has dots 55. The occupancy rate of the adhesive layer 53 provided in the second embodiment of the present disclosure also becomes smaller toward the second circuit board, similar to the adhesive layer 53 provided in the second embodiment. The adhesive layer main body 54 has a rectangular shape.

In this way, the occupancy rate of the adhesive layer 53 between the back surface of the display panel 12 and the heat sink 40 can be gradually reduced in the direction toward the second circuit board, which can uniformly heat the entire display panel 12 and reduce the visibility of uneven brightness on the display panel 12, thereby improving the display quality of the display device.

The adhesive layer 53 is preferably a printed material. The dots 55 are spaced apart, so the adhesive layer 53 can be easily formed in this way.

Figure 12 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel of the display device in the second embodiment of the present disclosure. It can be seen that in the display device in the second embodiment of the present disclosure, the heat of the source substrate (first circuit substrate) transmitted from the source driver can be dissipated slowly, and the temperature gradient on the surface on the bottom side of the display panel is small.

Figure 13 is a diagram showing the temperature distribution on the surface on the bottom side of the display panel of the display device in the second embodiment of the present disclosure. As shown in Figure 13, it can be seen that in the display panel of the display device in the second embodiment, the temperature change from the source driver toward the top side of the display panel is smaller than that of the display panel of the display device in the reference example.

As described above, the display device in the second embodiment of the present disclosure is able to reduce the temperature gradient near the heat source-substrate boundary located on the back surface of the display panel, making luminance unevenness in the display panel less noticeable and improving the display quality of the display device.

Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible that do not substantially deviate from the novelties and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning may be replaced with that different term anywhere in the specification or drawings. Furthermore, the configuration and operation of the display device are not limited to those described in each embodiment and each example of the present disclosure, and various modifications are possible.

10 Display device, 12 Display panel, 14 Frame, 24 Source board (first circuit board), 26 Fixing member, 28 Flexible board (second circuit board), 30 Source driver (heat source), 32 Heat insulating member, 40 Heat sink, 50, 52, 53 Adhesive layer, 51 Protrusion, 54 Adhesive layer body, 55 Dot, L Protrusion length, S Non-adhesive layer area

Claims (9)

a display panel for displaying an image;
a first circuit board disposed on an end side of the rear surface of the display panel;
a second circuit board having a heat source located closer to an end of the display panel than the first circuit board;
a heat sink disposed at a position different from a position on a rear surface of a display panel on which the first circuit board and the second circuit board are disposed;
an adhesive layer provided between the rear surface of the display panel and a portion of the heat sink;
Equipped with
11. A display device, comprising: a display panel including a back surface of the display panel and a heat sink, the back surface of the display panel being spaced apart from the heat sink by a distance that decreases in a direction toward the second circuit board. The display device according to claim 1, characterized in that the adhesive layer has a plurality of protrusions on the second circuit board side. The display device according to claim 2, characterized in that the tip of the protrusion is rounded. The display device according to any one of claims 1 to 3, characterized in that the adhesive layer is an adhesive tape. The adhesive layer has an adhesive layer body and dots,
2. The display device according to claim 1, wherein the dots are provided such that an occupancy rate of the dots decreases toward the second circuit board. The display device according to claim 5 , wherein the adhesive layer is a printed material. The display device according to any one of claims 1 to 6, characterized in that the second circuit board is disposed on the bottom side of the display panel. The display device according to any one of claims 1 to 7, characterized in that the first circuit board is a source board that controls the display of the display panel, the second circuit board is a connection board that connects the first circuit board and the display panel, and the heat source is a source driver for driving the display panel. The display device according to any one of claims 1 to 8, characterized in that the display panel is an organic EL panel using organic light-emitting diode elements.

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