JP2014021479A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device that can accurately detect a crack in a glass substrate in a fabrication step in a bonding part of a rewound flexible printed circuit (FPC) substrate and the glass substrate.SOLUTION: The display device has: a display panel that includes a glass substrate 101; and a flexible printed circuit (FPC) substrate 105 that is connected to the glass substrate 101. The glass substrate has glass crack detection wiring 130 formed in a junction part for bonding the rewound FPC substrate, and the FPC substrate has external wiring to be connected to the crack detection wiring 130.

Description

  The present invention relates to a display device including a flexible printed circuit (FPC) substrate.

  Liquid crystal display modules (liquid crystal display devices) are used in display devices of many portable information devices such as mobile phones, personal digital assistants (PDAs), digital cameras, and multimedia players.

  In these liquid crystal display modules such as mobile phones, there is an increasing need for thinning and narrowing the frame. A technique is known in which a flexible printed circuit (FPC) substrate connected to a TFT substrate is folded and placed on the back surface of the display unit in order to reduce the frame outside the display unit (narrow frame). On the other hand, Patent Document 1 discloses a technique for detecting a crack by forming a conductive film around a plate glass and measuring an electrical change of the conductive film.

JP 2005-53734 A

  The present inventors examined the unique configuration shown in FIG. 1 as a liquid crystal display device in which the FPC board is folded and fixed on the back side of the display unit. Reference numeral 101 denotes a TFT substrate (glass substrate), reference numeral 102 denotes a color filter (CF) substrate, reference numeral 103 denotes an upper polarizing plate, reference numeral 105 denotes an FPC board, reference numeral 107 denotes a driver, reference numeral 110 denotes a resin frame, reference numeral 111 denotes a metal frame, Reference numeral 132 denotes a connector. The liquid crystal layer is sealed between the TFT substrate 101 and the CF substrate 102. The liquid crystal display panel includes a TFT substrate, a color filter substrate, a liquid crystal layer, an upper polarizing plate, and a lower polarizing plate, and is held by a frame portion of a resin frame. FIG. 2 is a schematic cross-sectional view of the A-A ′ portion shown in FIG. 1. The FPC substrate 105 is connected to the end portion of the TFT substrate 101 on the front surface side and is bent to the back surface of the resin frame 110. Reference numeral 104 denotes a lower polarizing plate, and reference numeral 106 denotes an electronic component. The manufacturing process of the present liquid crystal display device is shown in FIGS. 8A to 8G.

  First, the upper polarizing plate 103 is attached to the CF substrate side of the bonded TFT substrate (glass substrate) 101 and the CF substrate 102, and the lower polarizing plate 104 is attached to the TFT substrate side. FIG. 8A shows a top view (display side) in this state, a cross-sectional view of the A-A ′ portion, and a bottom view (back side). Note that a protective film for suppressing external light reflection may be disposed on the upper polarizing plate 103. Moreover, you may arrange | position the brightness enhancement film for improving the utilization efficiency of the light from a backlight light source (not shown) to a lower polarizing plate.

  Next, the driver 107 for controlling the drive signal is thermocompression bonded to the TFT substrate 101 via the driver-mounted ACF (anisotropic conductive film) 108 (FIG. 8B). Subsequently, an FPC board 105 on which a liquid crystal display device is mounted, for example, for facilitating connection between a mobile phone side (not shown) and the driver 107 and enabling exchange of signals between them is provided. Then, thermocompression bonding is performed to the TFT substrate 101 through the ACF 109 for mounting the FPC (FIG. 8C). In the drawings, electronic components constituting a circuit formed on the FPC board are omitted.

  Next, a display panel including the CF substrate 102, the FPC substrate 105, and the TFT substrate 101 is attached to the resin frame 110 including the backlight unit (FIG. 8D). Since the liquid crystal layer has only the role of a shutter for adjusting brightness and color, a separate light source is required. Subsequently, the FPC board 105 is bent to the back side in accordance with the arrow 112 shown in FIG. 8D. In the state of FIG. 8D, since the FPC board 105 protrudes greatly below the resin frame 110, it becomes a factor which enlarges a product external shape. For this reason, the protruding FPC board 105 is folded back and the FPC board 105 is fixed using a tape attached to the resin frame 110 on the back side (FIG. 8E).

  Next, the FPC board 105 is wound back to the display surface side in accordance with the arrow 112 shown in FIG. 8E. Thereby, the metal frame of the next process can be attached. The FPC substrate 105 of the wound portion is attached to the TFT substrate 101 on the display surface side (FIG. 8F). Thereby, the liquid crystal module is completed. Subsequently, in order to increase the mechanical strength of the liquid crystal module, a metal frame 111 is pasted so as to cover the resin frame 110 on the back side of the liquid crystal module (FIG. 8G). As described above, the frame can be narrowed by connecting the FPC substrate to the glass substrate, folding it back to the back side of the resin frame, and then winding it back to the glass substrate side.

  As a result of evaluating the characteristics of the liquid crystal display device thus manufactured, it was found that a disconnection failure occurred. Therefore, the cause of this failure was investigated. As shown in FIGS. 1 and 8F, the present liquid crystal display device has a configuration in which the FPC substrate 105 is rolled back from the back surface side to the display surface side and attached to the TFT substrate (glass substrate) 101. As shown in FIG. 2, the affixing portion is substantially a single glass of the TFT substrate 101, and for the convenience of the layout of the electronic component 106 mounted on the FPC substrate 105, the resin frame 110 is made of a glass substrate. Since it has a structure that does not exist in the lower part, it has been found that cracks are likely to occur due to the application of a load at the time of pasting, which is a cause of disconnection failure. Note that there are many cracks on the short electronic component side. In addition, since the FPC board 105 covers the pasting part, it is difficult to detect glass cracks in the pasting part, and there is a concern that long-term reliability may be lacking even if conduction immediately after manufacture is apparently good. It was.

  The objective of this invention is providing the display apparatus which can detect the crack of the glass substrate in the junction part of a rewinding FPC board | substrate and a glass substrate with a high precision in the step of a manufacturing process.

  As one embodiment for achieving the above object, in a display device having a display panel including a glass substrate and a flexible printed circuit board connected to the glass substrate and provided with an electronic component, the glass substrate includes: A bonding portion for attaching another substrate (such as a rolled-up FPC substrate), a crack detection wiring for detecting a crack in the glass substrate formed in the bonding portion, and the crack detection wiring as an external wiring A display panel terminal for connection, and the flexible printed circuit board includes the external wiring connected to the display panel terminal and a crack inspection terminal for applying a voltage to the external wiring. The display device is characterized by this.

  Further, in a display device including a display panel including a glass substrate, a resin frame that holds the display panel, and a flexible printed circuit board that is connected to the glass substrate and includes an electronic component, the glass substrate is The flexible printed circuit board is connected to a first region on the glass substrate on the first side side, the first side and a second side orthogonal to the first side. In addition, it is bent to the back surface side along the first side and attached to the resin frame, and is further wound back along the second side to be on the second side side on the glass substrate. Affixed to the second region, the electronic component and the resin frame are disposed below the second region, and the glass substrate is formed in the second region. Said glass substrate A crack detection wiring for detecting a crack; and a display panel terminal for connecting the crack detection wiring to an external wiring; and the flexible printed circuit board is connected to the display panel terminal. A display device comprising: a wiring; and a crack inspection terminal for applying a voltage to the external wiring.

  ADVANTAGE OF THE INVENTION According to this invention, the display apparatus which can detect the crack of the glass substrate in the junction part of a rewinding FPC board | substrate and a glass substrate with a high precision in the step of a manufacturing process can be provided.

1 is a schematic overall plan view of a liquid crystal display device according to an inventor's study and according to embodiments of the present invention. FIG. 2 is a schematic sectional view of an A-A ′ portion of the liquid crystal display device shown in FIG. 1. It is a schematic plan view of the principal part of the liquid crystal display device which concerns on 1st Example of this invention. FIG. 4 is an enlarged plan view of a main part shown in FIG. 3. It is an enlarged plan view of the principal part in the liquid crystal display device which concerns on the 2nd Example of this invention. 1 is a schematic plan view of a main part of a liquid crystal display device according to a first embodiment of the present invention. It is a schematic plan view of the principal part of the liquid crystal display device which concerns on the 3rd Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating the manufacturing method of the liquid crystal display device which concerns on inventors' examination and which concerns on each Example of this invention. It is a figure for demonstrating that a crack detection is possible with the wiring for crack detection. It is a figure for demonstrating the effect of the wiring for crack detection in the liquid crystal display device which concerns on 1st Example of this invention.

The inventors have studied a configuration for detecting a crack in a glass substrate (TFT substrate) in a joint portion that is covered with an opaque rolled-up FPC substrate and is difficult to observe directly. It is thought that the presence or absence of cracks can be confirmed by providing crack detection wiring in the area and its vicinity and detecting the current value (resistance value) flowing through the wiring via an external input component such as an FPC board. It was. Therefore, when aluminum is used as the wiring material and ITO (indium tin oxide) is used, a crack detection wiring is formed on the glass substrate, and the effect of the presence or absence of cracks on the current value flowing through the crack detection wiring Examined. The applied voltage was 2V. The results are shown in FIG. When there was no crack, the current value was about 2.5 mA for the aluminum wiring, the resistance value was about 0.8 kΩ, and the ITO wiring was about 4.6 μA and about 500 kΩ, respectively. Since any material is also used for pattern formation other than the crack detection wiring, it is desirable that the film thickness as the crack detection wiring matches the film thickness required for these patterns. When there was a crack, the resistance value was ∞ (infinite) for any wiring material. This phenomenon does not change depending on the length and thickness of the crack and the wiring material. Therefore, the crack of the glass substrate can be detected by detecting whether the resistance in the crack detection wiring is a predetermined value or ∞, and the effectiveness of the crack detection wiring can be confirmed. In actual operation, since it is difficult to measure the resistance value of ∞, detection is performed based on the current value when a constant voltage is applied. When a constant voltage of 2 V is applied, about 2.5 mA flows in the case of aluminum wiring, and about 4.6 μA flows in the case of ITO wiring. When a glass crack occurs and breaks, the current value becomes 0 in all cases. Therefore, the threshold value of the current value is set to, for example, 1.0 mA for the aluminum wiring, 2.3 μA for the ITO wiring, and the glass crack can be detected by comparing the measured current with the threshold value. .
Hereinafter, an example explains. In addition, although an Example demonstrates using a liquid crystal display device, it is applicable also to other display devices, such as organic EL. Moreover, in each figure, the same code | symbol shows the same component.

  A first embodiment of the present invention will be described with reference to FIGS. The schematic overall configuration plan view of the liquid crystal display device is the same as FIG. The manufacturing method is basically the same as that shown in FIGS. 8A to 8G.

  FIG. 3 is a schematic plan view of a main part of the liquid crystal display device according to the present embodiment. A glass crack detection wiring (crack detection line) 130 is provided in the inner region of the lower right attaching portion (bonding portion) 210 of the TFT substrate (glass substrate) 101, and the end of the crack detection wiring 130 is connected to an external wiring. It is a display panel terminal for connection. As shown in FIG. 1, the folded portion of the FPC board attached to the back surface side of the resin frame 110 is attached to the attaching portion (joining portion) 210. Reference numeral 201 denotes an effective display area of the display panel.

  The FPC board 105 provided with the external wiring 131 connected to the crack detection wiring was attached to the glass substrate 101 (FIG. 6). In order to make the explanation easy to understand, description of a resin frame, a driver, and other wirings connected to the driver, etc. is omitted. Thereafter, a liquid crystal display device was manufactured through steps corresponding to FIGS. 8E to 8G. The occurrence of cracks after the manufacturing process (corresponding during the process) and after the accelerated test (corresponding after shipping) in FIG. 8F was examined through the connector (crack inspection terminal) 132. The results are shown in FIG. In the sample without a crack detection wiring (698 sample), 2.0% of glass cracks occurred during the process and 1.9% after shipment, and the cracked product could be removed only during the process. I found out. On the other hand, in the sample (852 sample) in which the crack detection wiring (crack detection line) was formed, 3.6% of glass cracks were detected during the process, but after the accelerated test (corresponding after shipment), the crack was detected. The occurrence of was not observed. As a result, it was confirmed that the generation of cracks after accelerated test (corresponding after shipment) can be suppressed / prevented by providing glass crack detection wiring.

  In addition, the crack detection 2nd wiring in the outer peripheral part of the whole glass substrate 101 can also be provided in parallel with the crack detection wiring (1st wiring) in a sticking part. In this case, no crack is generated, cracks are generated only in the second wiring part having a long wiring, cracks are generated only in the first wiring part having a short wiring, and cracks are generated in both the first and second wiring parts. Thus, the current flowing between the power supply terminals is gradually reduced (the resistance value is increased), so that it is possible to specify whether the crack is generated on the glass substrate pasting portion or the entire outer peripheral portion.

  As described above, according to the present embodiment, it is possible to provide a display device that can detect a crack in the glass substrate at the joint portion between the rolled-back FPC substrate and the glass substrate with high accuracy at the stage of the manufacturing process.

  A second embodiment of the present invention will be described with reference to FIG. Note that the matters described in the first embodiment but not described in the present embodiment can be applied to the present embodiment as long as there is no particular circumstance. FIG. 5 is an enlarged plan view of the crack detection wiring in the liquid crystal display device according to the present embodiment. The difference from the first embodiment is that in the first embodiment (FIG. 3), the crack detection wiring is arranged in a straight line, whereas in the present embodiment, it is a zigzag arrangement. The reason why the crack detection wiring is zigzag will be described below.

  Even if the crack detection wiring is linearly arranged as shown in FIG. 3, glass cracks can be detected with high accuracy at the stage of the manufacturing process. However, when the crack 220 generated in the glass substrate is generated so as to overlap with the crack detection wiring 130 as shown in FIG. For this reason, there is a possibility of missing a crack in the glass substrate 101. By making the crack detection wiring 130 zigzag, the possibility of this oversight can be reduced.

  The FPC board 105 provided with the external wiring 131 connected to the crack detection wiring was attached to the glass substrate 101 (FIG. 6). Note that the resin frame, the driver, and the like are omitted for easy understanding. Thereafter, a liquid crystal display device was manufactured through steps corresponding to FIGS. 8E to 8G. When the crack occurrence state after the process of FIG. 8F (corresponding during the process) and after the accelerated test (corresponding after shipping) was examined through the connector 132, a result equal to or better than that of FIG. 10 was obtained. Thus, it was confirmed that the generation of cracks after shipment can be suppressed / prevented by providing the glass crack detection wiring.

  As described above, according to the present embodiment, it is possible to provide a display device that can detect a crack in the glass substrate at the joint portion between the rolled-back FPC substrate and the glass substrate with high accuracy at the stage of the manufacturing process.

  A third embodiment of the present invention will be described with reference to FIG. Note that matters described in the first or second embodiment but not described in the present embodiment can also be applied to the present embodiment unless there are special circumstances.

  FIG. 7 is a schematic plan view of the main part of the liquid crystal display device according to the present embodiment, showing a configuration in which pads (crack inspection terminals) 135 are provided on the external wiring 131 shown in FIG. By providing the pad 135, it is possible to easily detect cracks in various products using the connection terminal for the pad 135 without preparing connector terminals having different shapes for each product.

  With respect to the structure shown in FIG. 7, a liquid crystal display device was manufactured through steps corresponding to FIGS. 8E to 8G. When the crack occurrence state after the process of FIG. 8F (corresponding during the process) and after the accelerated test (corresponding after shipping) was examined through the connector 132, the same result as FIG. 10 was obtained. Thus, it was confirmed that the generation of cracks after shipment can be suppressed / prevented by providing the glass crack detection wiring.

  As described above, according to the present embodiment, it is possible to provide a display device that can detect a crack in the glass substrate at the joint portion between the rolled-back FPC substrate and the glass substrate with high accuracy at the stage of the manufacturing process. Further, by providing a pad on the wiring in the FPC board connected to the crack detection wiring, it is possible to detect cracks with various terminals for various products.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. It is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

DESCRIPTION OF SYMBOLS 101 ... TFT substrate (glass substrate), 102 ... CF substrate, 103 ... Upper polarizing plate, 104 ... Lower polarizing plate, 105 ... FPC substrate, 106 ... Electronic component, 107 ... Driver, 108 ... ACF for driver, 109 ... For FPC ACF, 110 ... resin frame, 111 ... metal frame, 112 ... bending direction of FPC board, 130 ... wiring for crack detection, 131 ... external wiring, 132 ... connector, 135 ... pad, 201 ... effective display area, 210 ... FPC board Pasting part (joining part), 220 ... glass crack.

Claims (10)

In a display device having a display panel including a glass substrate, and a flexible printed circuit board connected to the glass substrate and provided with an electronic component,
The glass substrate is connected to a joint for attaching another substrate, a crack detection wiring for detecting a crack in the glass substrate formed in the joint, and the crack detection wiring to an external wiring. And display panel terminals for
The flexible printed circuit board includes the external wiring connected to the display panel terminal, and a crack inspection terminal for applying a voltage to the external wiring. The display device according to claim 1,
The display device, wherein the crack detection wiring is linearly arranged along a peripheral portion of the joint portion. The display device according to claim 1,
The display device according to claim 1, wherein the crack detection wiring is arranged in a zigzag shape around the joint. The display device according to claim 2, wherein
The other substrate is the flexible printed circuit board which is connected to the glass substrate, bent to the back side including the display panel, and further rolled back to the surface side of the display panel. Display device. The display device according to claim 4, wherein
The display device, wherein the crack inspection terminal is a connector provided at an end of the external wiring. The display device according to claim 1,
The display device, wherein the crack inspection terminal is a pad provided in the middle of the external wiring. In a display device having a display panel including a glass substrate, a resin frame that houses the display panel, and a flexible printed circuit board that is connected to the glass substrate and includes electronic components,
The glass substrate has a first side and a second side orthogonal to the first side;
The flexible printed circuit board is connected to the first region on the first side of the glass substrate, and is bent to the back side along the first side and attached to the resin frame. Attached to the second region on the second side on the glass substrate by being further rolled back along the second side,
In the lower part of the second region, the electronic component and the resin frame are arranged,
The glass substrate includes a crack detection wiring for detecting a crack in the glass substrate formed in the second region, and a display panel terminal for connecting the crack detection wiring to an external wiring. ,
The flexible printed circuit board includes the external wiring connected to the display panel terminal, and a crack inspection terminal for applying a voltage to the external wiring. The display device according to claim 7, wherein
The display device according to claim 1, wherein the crack detection wiring is arranged in a zigzag shape around the joint. The display device according to claim 7, wherein
The display device, wherein the crack inspection terminal is a connector provided at an end of the external wiring. The display device according to claim 7, wherein
The display device, wherein the crack inspection terminal is a pad provided in the middle of the external wiring.

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