Display apparatus with a flexible printed circuit board

A flexible printed circuit board and a display apparatus including the same, which can prevent damage due to static electricity is disclosed. The flexible printed circuit board includes a signal line region and a ground region protruding from the signal line region, wherein the external periphery of the signal line region is a conductive pattern unformed region where a conductive pattern is not formed. Additionally, at least a portion of the external periphery of the ground region is a conductive pattern formed region where a conductive pattern is formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Korean Patent Application No. 10-2012-0078302 filed on Jul. 18, 2012 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a display apparatus, and more particularly, to a display apparatus having a flexible printed circuit board.

2. Description of the Related Technology

Recent years have witnessed the widespread use of display apparatuses in a wide variety of products, including a television, a monitor, a notebook computer, a mobile phone, a personal digital assistant (PDA), a smart phone, and so on. Various product groups employing a display apparatus have different specification requirements. However, increasing the resolution of a display apparatus or reduction of the thickness of the display apparatus are common requirements, irrespective of product groups. To cope with the requirements, recently proposed display apparatuses include high-performance driving chips mounted therein to allow as many signal lines as possible to be densely populated in a narrow area and to process complex signals.

Meanwhile, the display apparatus is liable to be frequently exposed to external static electricity from the environment in which the display apparatus is used.

In particular, with the recent emphasis on the mobility of a display apparatus, the display apparatus is used in a variety of environments. Thus, a display apparatus may become more frequently exposed to the external static electricity. If static electricity is externally applied to the display apparatus, display quality may deteriorate and elements such as driving chips connected to signal lines may be damaged.

The present disclosure describes ways to effectively release the induced static electricity, including forming a ground pad on a flexible printed circuit board to make the same contact a sidewall of a bottom chassis. Since cutting is generally performed in the course of forming a flexible printed circuit board, a conductive pattern formed at an external periphery of the flexible printed circuit board is prone to damage. Therefore no conductive pattern is formed at the external periphery of the flexible printed circuit board. With this configuration in which a ground pad is formed on a flexible printed circuit board and contacts a sidewall of a bottom chassis, since there is no conductive pattern formed at the periphery at which the ground pad is stably brought into close contact with the bottom chassis due to a resilient force, ground contact resistance may increase, making it difficult to effectively release the induced static electricity.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The present disclosure provides a flexible printed circuit board, which can effectively release static electricity induced thereto. The flexible printed circuit board may be disposed within a display apparatus.

One aspect disclosed herein relates to a flexible printed circuit board comprising a signal line region having an external periphery; a ground region having an external periphery, the ground region protruding in a first direction from the signal line region; wherein the external periphery of the signal line region comprises a region where no conductive pattern is formed, and the external periphery of the ground region comprises a region where a conductive pattern is formed.

In some embodiments, the conductive pattern is formed on the entire external periphery of the ground region.

In some embodiments, the ground region includes a plurality of external peripheral sides, wherein the external peripheral side having a minimum angle formed with respect to a direction perpendicular to the first direction comprises a region where a conductive pattern is formed.

In some embodiments, the flexible printed circuit board comprises a panel connection region having an external periphery, the panel connection region protruding from the signal line region in a second direction, wherein the external periphery of the panel connection region is a region where no conductive pattern is formed.

In some embodiments, the first direction is perpendicular to the second direction.

In some embodiments, the first direction is parallel to the second direction.

In some embodiments, the ground region comprises a first ground region protruding from the signal line region in a third direction perpendicular to the second direction; and a second ground region protruding from the signal line region in the same direction as the second direction.

In some embodiments, the signal line region is covered by a passivation layer, and the ground region is not covered by the passivation layer.

Another aspect disclosed herein relates to a flexible printed circuit board comprising a base film; a signal line region comprising an external periphery; and a flexible printed circuit board comprising a conductive pattern formed on one surface of the base film, wherein a first portion of the external periphery of the signal line region is no conductive pattern formed thereon, and a second other portion of the external periphery of the signal line region has a conductive pattern formed thereon.

In some embodiments, the second portion of the external periphery of the signal line region is a ground region.

Another aspect disclosed herein relates to a display apparatus comprising a display panel; a bottom chassis configured to receive the display panel; and a flexible printed circuit board attached to a side of the display panel, comprising a signal line region and a ground region protruding from the signal line region, wherein an external periphery of the signal line region has no conductive pattern formed thereon, and at least a portion of an external periphery of the ground region has a conductive pattern formed thereon.

In some embodiments, at least a portion of the external periphery of the ground region contacts a sidewall of the bottom chassis.

In some embodiments, the entire external periphery of the ground region of the flexible printed circuit board has a conductive pattern formed thereon.

In some embodiments, the ground region includes a plurality of external peripheral sides, among which the external peripheral side having a minimum angle formed with respect to a direction perpendicular to a direction in which the ground region protrudes from the signal line region has a conductive pattern formed thereon.

In some embodiments, the flexible printed circuit board further comprises a panel connection region, wherein an external periphery of the panel connection region has no conductive pattern formed thereon.

In some embodiments, the ground region of the flexible printed circuit board protrudes from the signal line region in a direction perpendicular to the direction in which the panel connection region protrudes from the signal line region.

In some embodiments, at least a portion of the external periphery of the ground region of the flexible printed circuit board contacts a sidewall of the bottom chassis, which is adjacent to the side of the display panel to which the flexible printed circuit board is attached.

In some embodiments, the ground region of the flexible printed circuit board protrudes from the signal line region in the same direction as the direction in which the panel connection region protrudes from the signal line region.

In some embodiments, at least a portion of the periphery of the ground region of the flexible printed circuit board contacts a sidewall of the bottom chassis, which is adjacent to the side of the display panel to which the flexible printed circuit board is attached.

In some embodiments, the ground region comprises a first ground region protrudes from the signal line region in a direction perpendicular to the direction in which the panel connection region protrudes from the signal line region; and a second ground region protrudes from the signal line region in the same direction as the direction in which the panel connection region protrudes from the signal line region.

In some embodiments, the signal line region is covered by a passivation layer, and the ground region is not covered by the passivation layer.

Since contact resistance between a ground pad and a bottom chassis in a flexible printed circuit board installed in the display apparatus is reduced, the induced static electricity can be rapidly released to the bottom chassis. Therefore, damage to a device caused by induction of static electricity or reduction of display quality can be suppressed.

DETAILED DESCRIPTION

It will be understood that when an element or layer is referred to as being “on” another element or layer, it can be directly on the other element or layer or intervening elements or layers may be present. Like numbers refer to like elements throughout.

Hereinafter, a display apparatus will be described with regard to a liquid crystal display by way of example, but aspects of the present invention display apparatus are not limited thereto. The present disclosure can be applied to other types of display apparatuses such as an organic light emitting display (OLED) apparatus, a plasma display panel (PDP), and the like.

FIG. 1is an exploded perspective view of a display apparatus. Referring toFIG. 1, the display apparatus may include a display panel100and a light source assembly200.

The display panel100includes a first display substrate110, a second display substrate120facing the first display substrate110, and a flexible printed circuit board (FPC)300attached to the first display substrate110.

The first display substrate110may have a pixel area (PA) and a driving area (DA). The pixel area (PA) of the first display substrate110overlaps the second display substrate120while the driving area (DA) is not covered by the second display substrate120but is exposed.

The pixel area (PA) of the first display substrate110may include a plurality of gate lines extending in a first direction, a plurality of data lines extending in a second direction perpendicular to the first direction (not shown). A thin film transistor (not shown) that is a switching element may be formed at an intersection of each of the gate lines and each of the data lines. A pixel electrode (not shown) may be disposed in a region defined by the gate line and the data line. A gate electrode that is a control terminal of the thin film transistor is connected to the gate line, a source electrode that is an input terminal of the thin film transistor is connected to the data line, and a drain electrode that is an output terminal of the thin film transistor is connected to the pixel electrode through a contact (not shown). A channel of the thin film transistor may be formed as a semiconductor layer. The semiconductor layer may be disposed to overlap the gate electrode. The source electrode and the drain electrode may be spaced apart from each other about the semiconductor layer.

A driver for applying a driving signal to the pixel area (PA) may be formed in the driving area (DA) of the first display substrate110. As an example of the driver, a driver IC130mounted in the driving area (DA) is illustrated. In addition, a plurality of lines for inputting/outputting signals to/from the driver IC130may be formed in the driving area (DA) of the first display substrate110. Lines positioned at one side of the driver IC130are connected to the gate lines and the data lines. A plurality of bonding pads (not shown) may be formed in the driving area (DA) of the first display substrate110positioned at the other side of the driver IC130. At least some of the bonding pads are electrically connected to the driver IC130through the signal lines. In addition, the flexible printed circuit board300may be attached to the bonding pads by means of an anisotropically conductive film. The flexible printed circuit board300will later be described.

The second display substrate120is disposed to face the first display substrate110. The second display substrate120may include a plurality of red, green and blue color filters (not shown). Each color filter may correspond to each pixel electrode. Black matrixes may be disposed at boundaries and outermost parts of the respective color filters. A common electrode may be formed on the entire surface of the color filters.

A liquid crystal layer (not shown) may be interposed between the first display substrate110and the second display substrate120. Alignment layers may be formed on surfaces of the first and second display substrate110and120contacting the liquid crystal layer.

A sealing member (not shown), such as a sealant, may be disposed between the first display substrate110and the second display substrate120along peripheral parts of the respective display substrates110and120to make the first display substrate110and the second display substrate120combined to each other to be hermetically sealed.

A light source assembly200is disposed under the display panel100. The light source assembly200may include a light source210, a light guide plate220that guides light emitted from the light source210, and at least one optical sheet230that is disposed above the light guide plate220and modulates optical properties of the emitted light.

The light source210is formed at one side of the light guide plate220. The light source210may include, for example, a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCF), an external electrode fluorescent lamp (EEFL), and so on. Alternatively, the light source210may be formed at both sides of the light guide plate220.

The light guide plate220moves the light emitted from the light source210using total internal reflection and upwardly emits the light through a scattering pattern formed on the bottoms surface of the light guide plate220. Although not shown, a reflection sheet is formed under the light guide plate220to allow the downwardly emitted light from the light guide plate220to be upwardly reflected back.

The at least one optical sheet230is disposed on the light guide plate220. The at least one optical sheet230may include, for example, a diffusion film for diffusing incident light, a prism sheet for collecting the incident light, a brightness enhancing film for partially reflecting the incident linear polarized light, a liquid crystal film for partially reflecting the incident circular polarized light, a retardation film for changing circular polarized light into linear polarized light, and/or a protective film, or a combination of optical sheets230providing different properties may be used.

The light source210, the light guide plate220, and the optical sheet230may be configured to fit in or be received by the bottom chassis250. The display panel100may also be configured to fit in or be received by the bottom chassis250. The bottom chassis250may be made of a conductive material, for example, a metal. The bottom chassis250may have a bottom surface and sidewalls. The bottom surface of the bottom chassis250may be rectangular. In this case, the bottom chassis250may have four sidewalls.

Although not shown, the light source assembly200may further include a mold frame. In this case, the light source210, the light guide plate220and the optical sheet230may be configured to fit in mold frame which is configured to fit in the bottom chassis250.

The display apparatus may further include a top chassis400that covers peripheral parts of the display panel100and surrounds side surfaces of the display panel100and the light source assembly200.

FIG. 2is a layout view of an embodiment of a flexible printed circuit board andFIG. 3is a cross-sectional view of the flexible printed circuit board shown inFIG. 2.

First, a sectional structure of a flexible printed circuit board will be described. Referring toFIG. 3, as shown from the sectional view, the flexible printed circuit board300includes a base film310, a conductive pattern320formed on one surface of the base film310, and a passivation layer330covering at least a portion of the conductive pattern320.

The base film310may be made of, for example, a flexible insulating material such as polyimide.

The conductive pattern320may be made of a metal such as copper. The conductive pattern320may include a plurality of conductive patterns. The respective conductive patterns may be physically spaced apart from each other and electrically disconnected from each other. The conductive pattern320may be formed by patterning a conductive layer. For example, by stacking a conductive layer, such as a copper foil, on the entire surface of the base film310and removing the conductive layer of a partial region by etching. The region having the conductive layer may be region (I). A region in which a conductive layer is not formed or is removed once formed to then expose the base film310may be referred to as a region II. As shown from the plan view, the flexible printed circuit board300may be defined by the conductive pattern region, denoted region I and the conductive pattern unformed region, denoted region II.

The passivation layer330covers the conductive pattern320and is made of an insulating material to insulate and protect the conductive pattern320. In some embodiments, the passivation layer330may be formed of a coverlay film. In order to make the conductive pattern320contact an external device, the passivation layer330is formed at a region, so that conductive pattern320may be directly exposed to the outside.

Planar arrangement of the flexible printed circuit board300having the sectional structure will now be described. Referring toFIG. 2, the flexible printed circuit board300may have a panel connection region (RP), a signal line region (RS), an outer terminal connection region (RO), and a ground region (RG).

The panel connection region (RP) is a region attached to the display panel100and is positioned at one side of the flexible printed circuit board300. The panel connection region (RP) may include bonding pads320aformed of a plurality of conductive patterns. The bonding pads320amay be exposed to the outside without the passivation layer330formed thereon.

The outer terminal connection region (RO) is a region to which other printed circuit boards or input devices are connected and may be positioned at the other side of the flexible printed circuit board300. Although not shown, the outer terminal connection region (RO) may also include bonding pads formed of conductive patterns.

A plurality of signal lines320bformed of conductive patterns are positioned in the signal line region (RS), and at least some of the plurality of signal lines320bmay extend to the panel connection region (RP) and/or the outer terminal connection region (RO). The extending signal lines320bmay be connected to the bonding pads320a. The signal line region (RS) may be covered by the passivation layer330.

The ground region (RG) may include a ground pad320cformed of a conductive pattern. The conductive pattern forming the ground pad320cmay have a greater width and/or a wide area than the conductive pattern forming the bonding pads. The ground pad320c, by making a contact with an external element or device, such as the bottom chassis250may release the static electricity induced in the flexible printed circuit board300.

In the illustrated embodiment, the ground region (RG) is formed to protrude from the signal line region (RS) in a direction perpendicular to the direction in which the panel connection region (RP) protrudes from the signal line region (RS), but aspects of the present invention are not limited thereto.

In some embodiments, the ground pad320cof the ground region (RG) need not be covered by the passivation layer330but may be exposed to the outside.

As described above, the region I and the region II may be disposed over the entire surface of the flexible printed circuit board300in various combinations. The external periphery of the flexible printed circuit board300, excluding the ground region (RG), may be a region II. In other words, the conductive patterns320formed on the flexible printed circuit board300, excluding the ground region (RG), may be spaced apart from the external periphery of the flexible printed circuit board300. In general, the external periphery of the flexible printed circuit board300is a region that is easily exposed to physical, chemical external factors. In addition, the external periphery of the flexible printed circuit board300may be a region that is cut to form the flexible printed circuit board300to have a desired size and shape. As such, if the signal line320bassociated with data signal transfer, the bonding pads320a, etc. are directly exposed to external factors or cutting environment, they may be damaged, resulting in inferiority. The inferiority can be prevented by forming the conductive patterns320to be spaced a predetermined distance apart from the external periphery of the flexible printed circuit board300.

Meanwhile, in the ground region (RG) of the flexible printed circuit board300, the conductive pattern320forming the ground pad320cmay extend to the at least a portion of the external periphery of the ground region (RG). In the illustrated embodiment, the external periphery of the ground region (RG) has three external peripheral sides and the ground pad320cis formed to extend to the external peripheral sides of the ground region (RG). Therefore, in the illustrated embodiment, all of the external peripheral sides of the ground region (RG) may be in the region I. The larger an area of the ground pad320c, the faster the static electricity can be released to an external element contacting the ground pad320c. Therefore, the conductive pattern320extending to the external periphery is advantageous in releasing the static electricity. Meanwhile, the external periphery of the ground region (RG) may directly contact the external element. If the conductive pattern320is formed to extend to the external periphery of the ground region (RG), contact resistance between the conductive pattern320and the external element may be reduced, thereby rapidly releasing the static electricity, which will later be described.

In the ground region (RG), even if the conductive pattern320is formed to extend to the external periphery, the ground pad320csimply performs a ground function, such as releasing of static electricity. Therefore, even if the device is partially damaged due to external factors or cutting environment, device inferiority may not occur.

As shown in the plan view of the flexible printed circuit board300, a portion of the external periphery of the flexible printed circuit board300may be a region II, and the other portion of the external periphery of the flexible printed circuit board300may be a region I. Here, the region I may be a ground region (RG).

Hereinafter, a connection structure of the flexible printed circuit board300in the display apparatus will now be described.FIG. 4is a cross-sectional view of the display apparatus according to an embodiment of the present invention, taken along the line IV-IV′ shown inFIG. 1andFIG. 5is a cross-sectional view of the display apparatus, taken along the line V-V′ shown inFIG. 1.

Referring toFIGS. 4 and 5, in the flexible printed circuit board300, the panel connection region (RP) is attached to the driving area (DA) of the first display substrate110. In the attached region, an anisotropically conductive film150may be interposed between the flexible printed circuit board300and the first display substrate110. Bonding pads320aof the flexible printed circuit board300are exposed to directly contact a top surface of the anisotropically conductive film150without a passivation layer330formed thereon. Bonding pads140of the first display substrate110may directly contact a bottom surface of the anisotropically conductive film150.

The anisotropically conductive film150may include an adhesive resin151and conductive balls152. If heat and pressure are applied to the anisotropically conductive film150, the conductive balls152may electrically connect the bonding pads320aof the flexible printed circuit board300and the bonding pads140of the first display substrate110.

The flexible printed circuit board300has a first bend along the sidewall of the display panel100and a second bend toward a bottom surface of a light guide plate220. Accordingly, a signal line region (RS) of the flexible printed circuit board300may be received on a bottom surface of a bottom chassis250. The signal line region (RS) and the bottom chassis250may be insulated from each other by the passivation layer330.

Referring toFIG. 5, ground region (RG) of the flexible printed circuit board300is bent toward the sidewall of the bottom chassis250. The base film310of the flexible printed circuit board300may have a predetermined resilient force. In this case, as the flexible printed circuit board is bent, the resilient force exerts a force in the ground region (RG) in the direction opposite to the bent direction. Thus, the periphery of the ground region (RG) may be stably brought into close contact with the sidewall of the bottom chassis250, and held in contact by the resilient force of the ground region (RG).

Since the ground pad320cof the flexible printed circuit board300extends to the periphery of the ground region (RG), the ground pad320cmay stably contact the sidewall of the bottom chassis250. Therefore, even when the ground pad320cof the ground region (RG) does have full surface contact with the sidewall of the bottom chassis250, a contact between the ground pad320cof at least a portion of the external periphery and the sidewall of the bottom chassis250can be ensured. Therefore, contact resistance between the ground pad320cand the bottom chassis250is generally reduced, thereby rapidly releasing the static electricity induced in the flexible printed circuit board300to the bottom chassis250. The sidewall of the bottom chassis250which makes contact with the ground region (RG) may be any one of four sidewalls of the bottom chassis250, which is adjacent to the side of the first display substrate110to which the flexible printed circuit board300is attached.

FIG. 6is a layout view of an embodiment of a flexible printed circuit board.

Referring toFIG. 6, conductive pattern320c-1is selectively formed at a portion of the external periphery of a ground region (RG1). As described in reference toFIGS. 4 and 5, the entire external periphery of the ground region (RG1) is not stably brought into contact with the sidewall of the bottom chassis250. Rather, only the external periphery corresponding to a side of the ground region (RG1) is stably brought into contact with the bottom chassis250. Therefore, stable release of static electricity from a ground pad320c-1is enabled even if the conductive pattern320c-1is formed to extend to only some of a plurality of sides of the external periphery of the ground region (RG1).

In light of the foregoing, if the external periphery has a plurality of peripheral sides, the peripheral side at which the conductive pattern320c-1is selectively formed may be a peripheral side that is parallel with a bend line (BL) of the ground region (RG1) or formed at the smallest angle with respect to the bend line (BL). Here, the bend line (BL) may be perpendicular to the direction in which the ground region (RG1) protrudes from the signal line region (RS). In some embodiments, the peripheral side at which the conductive pattern320c-1is selectively formed may be a peripheral side that is farthest from the bend line (BL) of the ground region (RG1).

In the illustrated embodiment, the external periphery of the ground region (RG1) has a plurality of peripheral sides, but the external periphery of the ground region (RG1) may be a curved line. In this case, the external peripheral area of the ground region (RG1) in which the conductive pattern320c-1is selectively formed may be an area that is formed at the minimum angle with respect to the bend line (BL) and/or an area that is farthest from the bend line (BL).

FIG. 7is a layout view of another embodiment of a, flexible printed circuit board. Referring toFIG. 7, the flexible printed circuit board302has a plurality of external peripheral sides. Region I and region II are both formed in the respective external peripheral sides. In the illustrated embodiment, the region II is positioned at a portion of the external periphery of the ground region (RG2) and the region I is also positioned thereat, thereby allowing a ground pad320c-2and a bottom chassis250to be stably conducted. Therefore, the static electricity induced to the flexible printed circuit board302can be rapidly released toward the bottom chassis250.

FIG. 8is a layout view of another embodiment of a flexible printed circuit board.FIG. 8illustrates a stacked structure of a plurality of conductive patterns. Referring toFIG. 8, the flexible printed circuit board303according to the embodiment of the present invention may include a base film310, a first conductive pattern321formed on one surface of the base film310, a first passivation layer331covering at least a portion of the first conductive pattern321, a second conductive pattern322formed on the other surface of the base film310, and a second passivation layer332covering at least a portion of the second conductive pattern322. The base film310, the first conductive pattern321, and the first passivation layer331may be similar to those described with reference toFIGS. 2 and 3. The second conductive pattern322is may be similar to the first conductive pattern321, and may have several different pattern features. The second passivation layer332may be substantially similar to the first passivation layer331. However, the second conductive pattern322may be covered by the same area as that covering the first passivation layer331, but may be covered by a different area from that covering the first passivation layer331.

FIG. 9is a layout view of another embodiment of a flexible printed circuit board304. Referring toFIG. 9, in the flexible printed circuit board304a ground region (RG) protrudes from a signal line region (RS) to a panel connection region (RP).FIG. 9illustrates that two ground regions (RG31, RG32) protrude from the signal line region (RS) to the panel connection region (RP), but the present embodiment is exemplary, and the number of ground regions is not limited to two. As the flexible printed circuit board304is connected in the display apparatus, the ground regions (RG31, RG32) are stably brought into close contact with a sidewall of a bottom chassis250, as described in reference toFIGS. 4 and 5. In some embodiments, the sidewalls of the bottom chassis250which makes contact with the ground region (RG) may be the sidewall of the flexible printed circuit board304, which is adjacent to a side of the first display substrate110.

FIG. 10is a layout view of an embodiment of a flexible printed circuit board300. The flexible printed circuit board305includes both of a first ground region (RG) similar to that described with reference toFIG. 2and second ground regions (RG31, RG32) similar to those described with reference toFIG. 9. Therefore, when the flexible printed circuit board305is connected to the display apparatus, it can be stably grounded with respect to two sidewalls of the bottom chassis250, thereby rapidly releasing the static electricity induced to the flexible printed circuit board305.

Exemplary embodiments of the present invention have been disclosed herein, it is understood that the present invention should not be limited to these preferred embodiments but various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.