JPH0792480A - Display device - Google Patents

Abstract

PURPOSE:To provide a display device which is reduced in size and thickness without decreasing the reliability or operability. CONSTITUTION:A film cover ray 22 is formed on one surface of a flexible substrate 1 and an ink cover ray 23 is formed on the other surface. The flexible substrate 11 is folded forming a smooth curved surface with the film cover ray 22 out, the film cover ray 22 is cut in a beltlike shape conforming with an area which becomes the curved surface to form a slit, and a columnar support for the film cover ray 22 is left in the slit. In the area which becomes the folded curved surface, a circuit wire 13 is formed inside the folded part and extended avoiding the area of the support for the film cover ray 22. Further, the cover ray edges of both the surfaces of the flexible substrate 11 are shifted nearby the connection part between a display panel 15 and the flexible substrate 11 so that they do not overlap with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of a flat display device using liquid crystal / electroluminescence or plasma.

[0002]

2. Description of the Related Art Conventionally, in a mounting structure of a display device for driving a screen by a driving LSI such as a matrix type liquid crystal display device, as shown in FIG.
A COF (chip on film) method in which a TCP (tape carrier package) mounted with is mounted or a COG (chip on glass) method in which a driving LSI 16 is directly mounted on a display panel substrate 15 as shown in FIG. Has been converted.

In the COF method, a signal processed by the driving LSI is transmitted, while in the COG method, an input signal to the driving LSI is transmitted, respectively.
In both of the above methods, the display panel is supplied with an image signal and a scanning signal via a flexible substrate.

Here, a conventional technique will be described only for the COG system.

A flexible substrate 11 for supplying an input signal used in the COG type display device shown in FIG. 11 is usually made of a substrate made of polyimide, polyethylene terephthalate, polyester or the like, and circuit wiring made of copper foil is formed on the substrate. . Flexible substrates include a three-layer substrate in which a base material and a copper foil are attached using an adhesive, and a two-layer substrate in which the base material and the copper foil are directly attached without using an adhesive, The two-layer substrate is more flexible. Further, a coverlay is formed to protect the circuit wiring, and the electrodes on the substrate are plated with Ni \ Au, Sn, or solder, if necessary.

This flexible substrate includes a single-sided wiring substrate in which circuit wiring is formed only on one side of the base material and a double-sided wiring substrate in which circuit wiring is formed on both sides of the base material.

Further, the cover lay for protecting the circuit wiring on the flexible substrate is formed by printing a film cover lay in which a film sheet of polyimide or the like is adhered with an epoxy resin or the like and printing a polyimide ink or a resist ink and curing the same. There is an ink cover lay formed.

In the COG type display device shown in FIG. 11, since it is necessary to individually provide an input signal to each driving LSI 16, the number of connecting electrodes between the display panel substrate 15 and the flexible substrate 11 is considerably large. Will increase. Therefore,
In this case, by using a double-sided wiring board provided with through holes in the flexible board, a signal line common to each drive LSI is connected, and the number of electrodes for the flexible board 11 to receive a signal from an external circuit is also increased. This is advantageous in that it can be significantly reduced, the reliability is improved, the external circuit can be downsized, the flexibility of the outer shape design of the flexible substrate can be increased, and the display device can be made compact.

The flexible substrate and the display panel are usually electrically and mechanically connected via an anisotropic conductive film 17.

By the way, in recent years, downsizing of display devices
There is a strong demand for thinning, and even in the COG method, it is also attempted to make the entire display device compact by means of bending the flexible substrate 11. However, when the flexible substrate 11 is bent, due to the rigidity of the flexible substrate 11, a repulsive stress may act on the connecting portion between the display panel substrate 15 and the flexible substrate 11, and the connection may become unstable. Particularly in the case of a double-sided wiring board, the rigidity is high and the danger is great. Therefore, for example, as shown in Japanese Utility Model Laid-Open No. 4-70630,
A structure has been proposed in which the cover lay inside the bent portion is removed to the region where the bending ends.

[0011]

In order to reduce the repulsive stress of the bending when the miniaturization and thinning of the display device using the double-sided wiring flexible substrate is attempted by bending the flexible substrate, FIG. 12 is used. Bending with a crease is also performed as shown, but since the circuit wiring is easily broken at the position of the fold, it is preferable to fold with a smooth curved surface as shown in FIG. But,
In this case, a bending repulsive stress 18 acts on the connection portion between the display panel 15 and the flexible substrate 11, and if fixed in the bent state, there is a problem that unstable connection is likely to occur.

Therefore, when the ink cover lay, which is more flexible than the film cover lay, is used on both sides, the repulsive stress 18 is relieved considerably, but even in this case, the entire flexible substrate 11 is substantially uniformly flexible. Therefore, when bending is performed, there is a problem that it is difficult to define the bending position.

Further, as shown in Japanese Utility Model Application Laid-Open No. 4-70630, when the cover lay inside the bent portion has a structure in which the area where the bending ends is removed, the circuit wiring is not covered or protected by the cover lay. There are problems such as deterioration of insulation and disconnection of circuit wiring.

Therefore, as shown in FIG. 14, in the flexible substrate 11 with double-sided wiring, the circuit wiring 14 is formed only inside the bending, and only the cover lay 14 outside the bending without the circuit wiring is the region where the bending ends. However, even in this case, since the rigidity of the area where the cover lay 14 is removed is uniform, concentrated stress is generated at the connection part with the display panel 15 and the cover lay edge inside the fold, causing disconnection. There is a problem that it is easy and it is difficult to specify the bending position.

On the other hand, in the vicinity of the connecting portion between the display panel and the flexible substrate, there is a problem that concentrated stress is likely to act on the cover lay edge of the flexible substrate and the cover lay edge near the connecting portion is likely to be broken.

Therefore, an object of the present invention is to prevent a decrease in connection reliability by bending with a small repulsive stress, to easily define a bending position and to have an easy workability, and to reduce the insulation and the disconnection of circuit wiring. (EN) It is possible to provide a structure for bending a flexible substrate that does not generate, prevent concentrated stress at a cover lay edge near a connection portion, and provide a connection between a flexible substrate and a display panel that does not cause disconnection.

[0017]

According to the present invention described in claim 1, a display device driving LSI for driving a display panel on a substrate of the display panel, and the display panel via an anisotropic conductive film. In a display device that is connected to a flexible substrate through a flexible substrate, the circuit wiring connected to the substrate of the display panel is provided through the flexible substrate. In addition, a coverlay for protecting the circuit wiring is formed on both sides of the flexible substrate, and the types of these coverlays are different on both sides of the flexible substrate.

According to a second aspect of the present invention, one side of the flexible substrate is formed of a film cover lay, and the other side is formed of an ink cover lay.

According to a third aspect of the present invention, the flexible substrate has a structure that can be bent by drawing a smooth curved surface, and the cover lay outside the bending corresponds to a curved surface region. That is, a band-shaped punch is provided and a slit is formed.

According to a fourth aspect of the present invention, a columnar cover lay support is provided in the slit portion of the cover lay outside the fold, and the slit portion is separated into several places. .

According to a fifth aspect of the present invention, in the region where the flexible substrate is curved, circuit wiring is formed only on the inner surface of the bend, and the support portion of the coverlay outside the bend is formed. That is, the circuit wiring is routed so as to avoid the area.

According to a sixth aspect of the present invention, the cover lay edges of the cover lays formed on both sides of the flexible substrate for protecting circuit wiring have a vicinity of a connecting portion between the display panel and the flexible substrate. That is, they are formed in parallel with the edges of the display panel, and the positions of the cover lay edges are displaced on both sides of the flexible substrate.

[0023]

In the invention according to claims 1 and 2, different coverlays are formed on both surfaces of the flexible substrate. Here, the film coverlay is attached to one surface of the substrate, while the ink coverlay having excellent flexibility is printed on the other surface. Thus, the repulsive stress when the flexible substrate is bent is reduced.

In the invention according to claim 3, when the flexible board is bent with a smooth curved surface,
A band-shaped cutout is provided in the film cover lay and a slit is formed in the curved surface area of the outer surface of the fold.

Thus, the repulsive stress when the flexible substrate is bent is further reduced, and the bending position is uniquely defined.

Further, in the invention according to claim 4, some of the supports for the columnar film cover lay are left at the slits, and the slits are separated at several places. As a result, when the flexible substrate is bent at the slit portion, the support portion that is harder than the portion without the slit is difficult to bend, so that the slit portion that is more flexible than the surroundings does not have a crease and the disconnection can be prevented.

Further, in the invention according to claim 5, the circuit wiring is formed only on the inner surface of the region where the flexible substrate is curved, and the outer surface has no circuit wiring.

As a result, since the wiring is not routed around the slit portion where the film cover lay is removed, the circuit wiring is protected electrically and physically, and the insulation is not deteriorated.

However, the circuit wiring formed on the inner side is more likely to be broken in this support portion than in the region where the film cover lay is removed. Therefore, even when the support portion is provided by arranging the circuit wiring formed on the inner side while avoiding the support portion, the disconnection does not easily occur.

Further, in the invention according to claim 6, the cover lay edges on both surfaces of the flexible substrate are formed in the vicinity of the connection portion between the display panel and the flexible substrate, respectively, in parallel with the display panel edge, and the flexible substrate Are offset on both sides.

As a result, concentrated stress hardly acts on the cover lay edge of the flexible substrate, and it is possible to prevent the occurrence of disconnection.

[0032]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 3 is a sectional view showing an embodiment of the invention described in claims 1 and 2. In the figure, the types of cover lay are different on both sides of the flexible substrate 11, one side is formed by sticking the film cover lay 22, and the other side is formed by printing the ink cover lay 23.

FIG. 4 is a sectional view showing an embodiment of the invention described in claim 3, and FIG. 5 is a flexible substrate 11 shown in FIG.
It is a top view which opened. In FIGS. 4 and 5, the flexible substrate 11 is bent so as to draw a smooth curved surface, and the cover lay 14 on the outer side of the bending is provided with a band-shaped punch and a slit is formed corresponding to the region to be the curved surface. Has been done.

FIG. 6 is a plan view showing an embodiment of the invention described in claim 4. In FIG. In the figure, some columnar coverlay supports are left in the slits of the coverlay, and the slits are separated into several places.

FIG. 7 is a sectional view showing an embodiment of the invention described in claim 5, and FIG. 8 is a plan view in which the flexible substrate of FIG. 7 is opened. 7 and 8, in the region where the flexible substrate is curved, the circuit wiring 13 is formed only inside the bend, and the circuit wiring is not routed to the support portion 20 of the cover lay outside the bend. .

FIG. 9 is a sectional view showing an embodiment of the invention described in claim 6. In this figure, the flexible substrate 1
The cover lay edges of the cover lays 14 formed on both sides of 1 are formed in parallel with the display panel edges in the vicinity of the connection portion between the display panel 15 and the flexible substrate 11, and are positioned on both sides of the flexible substrate 11. It is out of alignment.

FIG. 1 is a sectional view showing an embodiment in which the invention described in claims 1 to 6 is applied to a COG type liquid crystal display device. In the figure, a display panel 15 and
The flexible substrate 11 that supplies an input signal to the driving LSI 16 mounted on the display panel 15 is electrically and mechanically connected via the anisotropic conductive film 17. On both sides of the flexible substrate 11, the film cover lay 22 is attached on the outside of the bend, and the ink cover lay 23 is printed on the inside.

The film cover lay 22 is provided with a slit-shaped cutout 19, and the flexible substrate 11 is bent in the area of the slit 19 so as to draw a smooth curved surface.

Further, the cover lay edge between the film cover lay 22 and the ink cover lay 23 near the connecting portion is
It is designed to be offset so that they do not overlap.

FIG. 2 is a plan view showing a state in which the flexible substrate 11 is folded in the embodiment shown in FIG. In this figure, a column-shaped support 20 is provided in the slit 19 of the film cover lay, and the slit is divided into several.

Then, the circuit wiring 1 in the area of the slit 19
No. 3 is routed only inside the fold, and this route is designed so as to avoid the support portion of the slit. In the case of using a two-layer polyimide flexible substrate having a base material thickness of 27 μm and a copper foil thickness including a plating thickness of about 40 μm as the flexible substrate, the present invention is carried out in order to obtain good bendability. did. A 25 μm thick polyimide film cover lay is attached to the outside of the fold with a 35 μm thick adhesive, and a polyimide ink cover lay is printed about 15 μm inside the fold to provide a slit of 1.7 mm wide film cover lay. The slits were provided with a 2 mm film cover lay support every 20 mm, and a bending durability test against 180 ° bending of φ1.1 mm was performed. As a result, very good bending resistance was exhibited. Further, the bending position was uniquely defined, and the workability was improved and the shape and dimension accuracy after bending were good. In addition, the anisotropic conductive film 17
Connection between display panel and flexible board using
Good reliability was shown with the folds fixed. Furthermore, when the distance from the display panel edge to the ink cover lay edge was set to be 0.3 mm larger than the distance to the film cover lay edge, the occurrence of disconnection in the vicinity of the connection portion between the display panel and the flexible substrate was suppressed. .

Although the COG type liquid crystal display device has been particularly described in the above embodiments, the present invention is not limited to this, and the COF type and further mounting with connection between a general substrate and a flexible substrate. It goes without saying that it can be applied to the structure.

[0044]

As is apparent from the above, in the display device of the invention according to claims 1 and 2, the coverlay for protecting the circuit wiring of the flexible substrate having the circuit wiring formed on both surfaces is flexible. Different on both sides of the substrate, one side is formed with a film cover lay and the other side is formed with an ink cover lay, so the repulsive stress is reduced compared to when the film cover lay is formed on both sides, so the flexible substrate was bent In this state, the connection reliability between the display panel and the flexible substrate is improved.

According to a third aspect of the present invention, there is provided a display device having a structure in which a flexible substrate having circuit wiring formed on both surfaces is bent so as to draw a smooth curved surface. Since the slits are provided and the repulsive stress is reduced, the connection reliability between the display panel and the flexible substrate when the flexible substrate is bent is improved, and the bending position is uniquely defined. Therefore, it is possible to improve the workability and the accuracy of the shape and dimension when bent.

In the display device of the invention according to claim 4, some of the supports of the columnar film cover lay are left in the slit portion and the slit is separated at several places, and the flexible substrate is bent at the slit portion. When it is opened, since the support part that is harder than the part without the slit is difficult to bend, the slit part, which is more flexible than the surroundings, does not have a crease, and it is possible to prevent disconnection and improve reliability.

In the display device according to the fifth aspect of the present invention, the circuit wiring is formed only on the inner surface of the region where the flexible substrate is curved, the outer surface has no circuit wiring, and the film cover lay is removed. Since the wiring is not routed around the slit part, the circuit wiring is protected electrically and physically, the insulation does not deteriorate, and the occurrence of disconnection is suppressed, which reduces reliability. Can be prevented.

In the display device of the invention according to claim 6, the cover lay edges on both sides of the flexible substrate are formed in parallel with the display panel edge in the vicinity of the connection portion between the display panel and the flexible substrate, respectively, and are flexible. Since the cover lay edge of the flexible substrate is offset on both sides of the substrate, it is difficult for concentrated stress to act on the cover lay edge of the flexible substrate. Therefore, it is possible to prevent the occurrence of disconnection and prevent the deterioration of reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment applied to a COG type liquid crystal display device of the present invention.

FIG. 2 is a plan view showing a state in which a flexible substrate of the embodiment shown in FIG. 1 is open for bending.

FIG. 3 is a cross-sectional view for explaining an embodiment of the invention described in claim 1.

FIG. 4 is a cross-sectional view for explaining an embodiment of the invention described in claim 2.

FIG. 5 is a plan view showing a state in which the flexible board of the embodiment shown in FIG. 3 is open for bending.

FIG. 6 is a plan view for explaining an embodiment of the invention described in claim 3;

FIG. 7 is a sectional view for explaining an embodiment of the invention described in claim 4.

FIG. 8 is a plan view showing a state in which the flexible board of the embodiment shown in FIG. 6 is opened.

FIG. 9 is a cross-sectional view for explaining an embodiment of the invention described in claim 5.

FIG. 10 is a plan view of a conventional COF type liquid crystal display device.

FIG. 11 is a plan view of a conventional COG type liquid crystal display device.

FIG. 12 is a cross-sectional view showing an example of conventional folding to make a crease.

FIG. 13 is a cross-sectional view showing an example of conventional bending that draws a smooth curved surface.

FIG. 14 is a cross-sectional view showing an example of a structure in which only a conventional outer cover lay is pulled out to a region where bending ends.

[Explanation of symbols]

 11 ... flexible substrate 12 ... base material of flexible substrate 13 circuit wiring 14 coverlay 15 ... display panel 16 ... display device driving LSI 17 ... anisotropic conductive film 18 ... repulsive stress 19 ... film coverlay slit 20 ... slit support 21 Tape carrier 22. Film cover lay 23. Ink cover lay

Claims (6)

[Claims] 1. A display device driving LSI for driving a display panel on a display panel substrate, and a display device in which the display panel is connected to a flexible substrate via an anisotropic conductive film. In a display device supplied through a flexible substrate on which circuit wiring connected to the above is formed, the flexible substrate has circuit wiring formed on both surfaces, and a coverlay for protecting the circuit wiring is further provided. A display device, which is formed on both sides of a flexible substrate, and the types of these coverlays are different on both sides of the flexible substrate. 2. The display device according to claim 1, wherein one surface of the flexible substrate is formed of a film cover lay, and the other surface of the flexible substrate is formed of an ink cover lay. 3. The flexible substrate has a structure that can be bent while drawing a smooth curved surface, and a cover lay outside the bending is provided with a band-shaped punch corresponding to a region to be a curved surface, and a slit is formed. The display device according to claim 1, wherein 4. The display device according to claim 3, wherein a columnar cover lay support is provided in the slit portion of the cover lay outside the fold, and the slit portion is separated into several places. 5. The circuit wiring is formed only on the inner surface of the bend in a region where the flexible substrate is curved,
The display device according to claim 4, wherein the circuit wiring is routed so as to avoid the area of the support portion of the coverlay outside the fold. 6. The cover lay edge of a cover lay for protecting circuit wiring formed on both surfaces of the flexible substrate is formed in the vicinity of a connection portion between the display panel and the flexible substrate and in parallel with the display panel edge. The display device according to claim 1, wherein the cover lay edges are displaced on both sides of the flexible substrate.