JP2007293084A - Wiring substrate and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring substrate capable of reducing an increase of the area of a substrate, and to provide a display device provided with the wiring substrate. <P>SOLUTION: The wiring substrate as an LED mounting substrate 170 on which a wiring pattern 175 is formed is provided with: LEDs 160a to 160d mounted on an LED mounting part 171a; the wiring pattern 175 which is formed on an extension part 171b extended from the LED mounting part 171a and is connected with the LEDs 160a to 160d; an anode terminal 172a and a cathode terminal 172b formed on a terminal part 171c disposed at the end of the extension part 171b and connected with the LEDs 160a to 160d via the wiring pattern 175; and a protection element 190 which is disposed on the terminal part 171c and protects the LEDs. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring board and a display device, and more particularly to a wiring board on which a light source is mounted and a display device using the wiring board.

  In recent years, display devices such as liquid crystal display devices have been incorporated into many electronic devices such as mobile phones, portable information terminals, electronic notebooks, and portable televisions. For example, the liquid crystal display device includes a non-light emitting liquid crystal display element and a backlight unit that irradiates light toward the back surface of the liquid crystal display element.

  In order to reduce the size, LEDs are used as the light source of the backlight unit. This LED is provided, for example, on a flexible printed circuit board (hereinafter referred to as FPC) on which a predetermined wiring pattern is formed. Furthermore, a liquid crystal module having a configuration in which a Zener diode for protecting an LED is arranged on an FPC is disclosed (Patent Document 1).

JP 2004-258599 A

  However, the liquid crystal module of Patent Document 1 has a problem that the light source mounting portion of the wiring board cannot be reduced in size because the Zener diode is disposed in the vicinity of the light source. Therefore, there is a problem that it is difficult to reduce the size of the liquid crystal display device.

  The present invention has been made in view of such problems, and an object thereof is to provide a wiring board and a display device that can reduce an increase in the substrate area of a light source mounting portion.

  A wiring board according to a first aspect of the present invention is a wiring board on which a wiring pattern is formed, the light source mounted on the light source mounting part of the wiring board, and the light source mounting part of the wiring board extending from the light source mounting part A wiring pattern formed in the extended portion and electrically connected to the light source, and a terminal portion provided at an end of the extended portion of the wiring board, and the light source via the wiring pattern And a protective element that protects the light source is disposed on the terminal portion. Thereby, the increase in the board area of a light source mounting part can be reduced.

  In the wiring board according to the second aspect of the present invention, in the terminal portion, a dummy connector terminal is provided between the terminals connected to the light source, and the protection element is disposed in the vicinity of the dummy connector terminal. It is what. Thereby, the said protection element can be easily arrange | positioned to a terminal part. By using the above wiring board for a display device, the display device can be miniaturized.

  ADVANTAGE OF THE INVENTION According to this invention, the wiring board which can reduce the increase in the board | substrate area of a light source mounting part, and a display apparatus can be provided.

  Hereinafter, embodiments to which the present invention can be applied will be described. The following description explains the embodiment of the present invention, and the present invention is not limited to the following embodiment.

  An embodiment of the present invention will be described with reference to FIG. 1 and FIG. 1A and 1B are schematic views illustrating the configuration of a backlight unit, in which FIG. 1A is a front view of the backlight unit, and FIG. 1B is a cross-sectional view. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device including a backlight unit.

  As shown in FIGS. 1A and 1B, the holder 110 is a member formed of a resin or the like into a box shape having walls around it. A reflection sheet 120, a light guide plate 130, a prism sheet 140, and a diffusion sheet 150 are sequentially laminated on the inner side surrounded by the wall of the holder 110, and are fixed by an adhesive material such as a double-sided adhesive tape. Furthermore, a plurality of light emitting diodes (hereinafter referred to as LEDs (Light Emitting Diodes)) 160a to 160d as light sources disposed on the light incident surface 130a side which is the side end surface of the light guide plate 130 are provided.

  The plurality of LEDs 160a to 160d are respectively mounted on the LED mounting substrate 170, and are arranged on the light incident surface 130a side of the light guide plate 130 after the backlight unit 100 is assembled. The LED mounting substrate 170 is attached to the front side of the light guide plate 130 on one side (the light incident surface 130a side) with an adhesive material 180 such as a double-sided adhesive tape. Therefore, the LEDs 160 a to 160 d are included in the holder 110. The LED mounting substrate 170 is, for example, a flexible printed wiring board (FPC) on which a predetermined wiring pattern is formed.

  The light from the plurality of LEDs 160a to 160d is incident on the inside of the light guide plate 130 from the light incident surface 130a that is the side end surface of the light guide plate 130. The light is emitted toward the back side of the liquid crystal display panel 200.

  Here, the reflection sheet 120 reflects the light incident on the light guide plate 130 from the LEDs 160a to 160d toward the liquid crystal display panel 200 side. The light guide plate 130 emits light from the plurality of LEDs 160a to 160d from the light incident surface 130a into a planar light and emits it from the front surface so that light is uniformly incident on the display area of the liquid crystal display panel 200.

  The prism sheet 140 collects light so that the in-plane luminance of the liquid crystal display element is increased. The diffusion sheet 150 diffuses the light incident from the prism sheet 140 and makes the brightness of the display area of the liquid crystal display panel 200 uniform.

  As shown in FIG. 2, a liquid crystal display panel 200 is provided on the front side of the diffusion sheet 150. The liquid crystal display panel 200 is typically configured by sandwiching liquid crystal (not shown) between a pair of transparent substrates 210 and 220 each having an electrode formed on the inner surface.

  A driving circuit 230 for driving the liquid crystal display panel 200 is mounted on the front surface on one side of the transparent substrate 220, and a panel substrate 240 connected to an external circuit (not shown) is further connected. Then, the liquid crystal display panel 200 is irradiated with light from the backlight unit.

  As shown in FIGS. 1 and 2, the plurality of LEDs 160 a to 160 d as light sources are mounted on an LED mounting substrate 170, respectively. The plurality of LEDs 160a to 160d are arranged on the light incident surface 130a side of the light guide plate 130 after the backlight unit 100 is assembled. The number of LEDs mounted on the LED mounting substrate 170 is not necessarily plural, and may be one.

  As shown in FIG. 1 and FIG. 2, the back surface of the LED mounting substrate 170 is provided so as to face the front surface direction of the backlight unit 100. That is, the LED mounting substrate 170 is disposed so that the anti-LED mounting surface is on the liquid crystal display panel 200 side. The LED mounting substrate 170 is overlapped with a part of the light guide plate 130, and the overlapping portion is attached by an adhesive material 180 such as a double-sided adhesive tape.

  The LED mounting substrate 170 extends to the outside of the holder 110. Further, a protection element 190 for protecting the LEDs 160a to 160d is mounted on the LED mounting substrate 170. The protective element 190 is disposed outside the holder 110. The protection element 190 is mounted on the LED mounting surface of the LED mounting substrate 170. The protection element 190 is, for example, a Zener diode for preventing a surge voltage from being applied to the LEDs 160a to 160d.

  As shown in FIG. 2, the panel substrate 240 is also extended to the outside of the holder 110. Further, a connector 250 for connecting to the LED mounting substrate 170 is mounted on the panel substrate 240. The connector 250 is provided on the back surface of the panel substrate 240. By inserting a terminal provided at the end of the LED mounting substrate 170 into the connector 250, the connector 250 and the LED mounting substrate 170 are connected. Thereby, it is possible to supply power to the LEDs 160a to 160d via the panel substrate 240. The panel substrate 240 is, for example, an FPC. And the part outside the holder 110 among the panel substrate 240 and the LED mounting substrate 170 is bent and arranged on the back side of the backlight unit 100.

  Next, the configuration of the LED mounting substrate 170 is connected using FIG. 3 and FIG. FIG. 3 is a plan view schematically showing the configuration of the LED mounting substrate 170. FIG. 4 is a diagram schematically showing a circuit of the LED mounting substrate 170.

  As shown in FIG. 3, the LED mounting substrate 170 is roughly divided into three parts, that is, an LED mounting part 171a, an extending part 171b, and a terminal part 171c. Therefore, the LED mounting substrate 170 is bent at 90 ° at two locations, and is substantially U-shaped. The LED mounting portion 171a is a region where the LEDs 160a to 160d are mounted.

  The LED mounting portion 171a is accommodated in the holder 110 as shown in FIG. Limiting resistors 161a to 161d are mounted on the LED mounting portion 171a. The limiting resistors 161a to 161d are provided corresponding to the LEDs 160a to 160d. The limiting resistors 161a to 161d limit the current flowing through the LEDs 160a to 160d. The limiting resistors 161a to 161d are disposed on the light emitting side of the LEDs 160a to 160d. In FIG. 3, the wiring pattern 175 provided in the LED mounting portion 171a is not shown.

  The extending portion 171b extends from the side of the LED mounting portion 171a. That is, the extending portion 171b extends from the side end opposite to the direction in which light is emitted from the LEDs 160a to 160d of the LED mounting portion 171a. The extending portion 171 b is disposed outside the holder 110. A wiring pattern 175 from the LEDs 160a to 160d is formed in the extended portion 171b. The wiring pattern 171b formed in the extended portion 171b is electrically connected to the LEDs 160a to 160d. In FIG. 3, a part of the wiring pattern 175 provided in the extended portion 171 b is omitted in the drawing.

  A terminal portion 171c is provided at the end of the extending portion 171b. An anode terminal 172a, a cathode terminal 172b, and an NC terminal 174 are provided at the tip of the terminal portion 171c. As described above, the anode terminal 172a, the cathode terminal 172b, and the NC terminal 174 are inserted into the connector 250. The anode terminal 172a is connected to the anodes of the LEDs 160a to 160d, and the cathode terminal 172b is connected to the cathodes of the LEDs 160a to 160d. And a current flows into LED160a-160d by applying a voltage to anode terminal 172a and cathode terminal 172b. That is, the anode terminal 172a and the cathode terminal 172b are current supply terminals for supplying current to the LEDs 160a to 160d. The NC terminal 174 is a dummy connector terminal and is not connected to any of them. The pitch between the terminals of the anode terminal 172a, the cathode terminal 172b, and the NC terminal 174 is, for example, 0.3 to 0.5 mm.

  Here, two NC terminals 174 are arranged between the anode terminal 172a and the cathode terminal 172b. Thereby, the space | interval of the anode terminal 172a and the cathode terminal 172b can be widened. Therefore, short-circuit between the anode and the cathode can be prevented. In the terminal portion 171c, the interval between the wiring patterns 175 is widened by the NC terminal 174. Therefore, the width of the terminal portion 171c is wider than that of the extending portion 171b. The widths of the terminal portion 171c and the extending portion 171b indicate the length in a direction perpendicular to the direction in which the wiring pattern 175 is formed. That is, the length in the direction perpendicular to the direction in which the wiring pattern 175 is formed is longer in the terminal portion 171c than in the extending portion 171b.

  A wiring pattern 175a is extended from the anode terminal 172a to the anodes of the LEDs 160a to 160d, and a wiring pattern 175b is extended from the cathode terminal 172b to the cathodes of the LEDs 160a to 160d. That is, the wiring patterns 175a and 175b are connected to the LEDs 160a to 160d through the extending portion 171b. Lands 177 are formed in the middle of the wiring patterns 175a and 175b, respectively. The two lands 177 are disposed on the terminal portion 171c. That is, the land 177 is formed in the vicinity of the anode terminal 172a, the cathode terminal 172b, and the NC terminal 174. In the land 177, the metal is exposed. Further, the surface of the land 177 may be plated. The land 177 is provided wider than the wiring pattern 175.

  A protection element 190 is connected to the land 177. That is, the mounting terminal 191 of the protection element 190 and the land 177 are connected by solder or the like. Thereby, the protection element 190 is fixed to the LED mounting substrate 170. The size of the protection element 190 is, for example, 1.6 mm × 0.8 mm. Here, the protection element 190 mounted on the LED mounting substrate 170 is disposed in the terminal portion 171c. That is, the protection element 190 is disposed in the vicinity of the anode terminal 172a, the cathode terminal 172b, and the NC terminal 174. Therefore, the board area of the LED mounting portion 171a of the LED mounting board 170 can be reduced. That is, the terminal portion 171c is formed wider than the extending portion 171b in which only the wiring pattern 175 is formed. For this reason, the terminal part 171c is easy to take the surplus space for mounting the protective element 190 compared with the extension part 171b. Therefore, the protective element 190 can be easily mounted without increasing the substrate area.

  Further, in the present embodiment, the NC terminal 174 is disposed between the anode terminal 172a and the cathode terminal 172b. Thereby, in the terminal part 171c, the space | interval of the two wiring patterns 175 is wide. A protection element 190 is disposed in a region corresponding to the NC terminal 174. That is, the protective element 190 is disposed in the region between the two wiring patterns 175. In other words, the protective element 190 is disposed on an extended line extending from the NC terminal 174 in the direction in which the wiring pattern 175 is formed. Thus, by mounting the protective element 190 between the two wiring patterns 175 that are formed to be separated from each other by the NC terminal 174, the wiring pattern 175 can be changed according to the size of the protective element 190. There is no need to bypass. As a result, the pattern layout of the wiring pattern 175 can be simplified, and an increase in the substrate area can be prevented. As described above, the NC terminal 174 serving as a dummy connector terminal is disposed between the anode terminal 172a and the cathode terminal 172b. Then, the protective element 190 is arranged in a region corresponding to the NC terminal 174. In the area corresponding to the NC terminal 174, it is not necessary to form the wiring pattern 175, so that it is easy to become an excess space. Thereby, the protective element 190 is arrange | positioned in the vicinity of NC terminal 174, and the increase in a board | substrate area can be prevented.

  Further, unlike the LED mounting portion 171a, the terminal portion 171c is not included in the holder 110. That is, the terminal portion 171 c is disposed outside the holder 110. Therefore, the frame area around the display area of the display device can be narrowed, and the display device can be downsized. Furthermore, it is possible to add an LED to a space corresponding to the protective element 190 in the vicinity of the LEDs 160a to 160d. Therefore, the number of LEDs can be increased without increasing the wiring board area, and the luminance can be improved.

  As shown in FIG. 4, four LEDs 160 a to 160 d are arranged in parallel between the two wiring patterns 175. A limiting resistor 161a is connected in series to the LED 160a. The current flowing through the LED 160a is limited by the limiting resistor 161a. Similarly, limiting resistors 161b to 161d are connected in series to the LEDs 160b to 160d, respectively. Therefore, one LED and one limiting resistor are paired and connected in series between the wiring patterns 175. Between the two wiring patterns 175, four pairs of one LED and one limiting resistor are connected in parallel. Accordingly, when a voltage is applied to the anode terminal 172a and the cathode terminal 172b, a current flows through the LEDs 160a to 160d via the wiring pattern 175. This current causes the LEDs 160a to 160d to emit light.

  Further, a protective element 190 is connected between the two wiring patterns 175. That is, the four LEDs 160 a to 160 d and the protection element 190 are connected in parallel between the two wiring patterns 175. The protection element 190 is, for example, a Zener diode. Therefore, even when a reverse voltage is applied to the anode terminal 172a and the cathode terminal 172b due to static electricity or the like, the LEDs 160a to 160d can be protected. Thereby, damage of LED160a-160d can be prevented.

  Next, a state where each terminal is inserted into the connector 250 will be described with reference to FIG. FIG. 5A is a side view showing a state in which the LED mounting board 170 is connected to the connector 250. FIG. 5B is a side view showing a state in which the LED mounting board 170 having another configuration is connected to the connector 250. As shown in FIG. 5A, the tip of the terminal portion 171 c is inserted into the connector 250. A mounting terminal 251 is provided on the side surface of the connector 250. The mounting terminal 251 and the panel substrate 240 are connected by solder or the like. Thereby, the connector 250 is mounted on the panel substrate 240. That is, the wiring pattern provided on the panel substrate 240 and the connector 250 are electrically connected.

  Then, the tip of the terminal portion 171 c is inserted into the connector 250. As a result, the anode terminal 172a and the cathode terminal 172b are electrically connected to the socket and the like inside the connector 250. Therefore, the power supply voltage is supplied to the anode terminal 172a and the cathode terminal 172b through the panel substrate 240. For example, the cathode terminal 172b is grounded, and the anode terminal 172a is + 5V.

  The protective element 190 is disposed between the panel substrate 240 and the LED mounting substrate 170. That is, the protective element 190 is disposed between the panel substrate 240 and the LED mounting substrate 170 that are disposed to face each other. Further, a reinforcing plate 179 is formed on the side opposite to the mounting surface of the LED mounting substrate 170. The reinforcing plate 179 is disposed on the terminal portion 171c. The reinforcing plate 179 reinforces the LED mounting substrate 170. As a result, the LED mounting substrate 170 can be easily inserted into the connector 250. Here, the reinforcing plate 179 is disposed on the front end side of the LED mounting substrate 170 from the portion where the protection element 190 is mounted.

  As shown in FIG. 5B, the protective element 190 may be disposed so as to contact the connector 250. That is, in a state in which the connector 250 is inserted, the side surface on the insertion port side of the connector 250 and the side surface of the protection element 190 may be arranged close to each other. Thereby, it can be confirmed immediately whether it is surely inserted in the connector 250 or not. That is, when the LED mounting substrate 170 is securely mounted on the connector 250, the side surface of the connector 250 and the side surface of the protection element 190 are close to each other. On the other hand, when the LED mounting substrate 170 is inserted with an inclination with respect to the connector 250, a part of the protection element 190 is separated from the connector 250. By visually confirming the positional relationship between the protective element 190 and the connector 250, it can be confirmed whether or not the protective element 190 and the connector 250 are securely inserted. Therefore, poor insertion can be prevented.

  With the above configuration, it is possible to prevent an increase in the area of the LED mounting portion of the wiring board on which the LED is mounted. In the above description, the liquid crystal display panel has been described as an example, but the present invention is not limited to this. The above configuration can be applied to a wiring board on which a light source is mounted. The substrate for mounting the light source is not limited to the FPC, and may be a rigid wiring substrate made of glass epoxy resin or the like. In this manner, the display device can be miniaturized by connecting the wiring board having the above structure to the display panel using ACF or the like.

  Furthermore, you may apply to the structure which mounts light sources other than LED on a wiring board. The protection element 190 may be an element other than a Zener diode. Further, the shape of the wiring board is not limited to the U-shape. For example, a wiring board bent in an L shape may be used. Further, it may be a wiring board bent a plurality of times.

It is a figure which shows typically the structure of the backlight unit of the display panel concerning embodiment of this invention. It is sectional drawing which shows typically the structure of the display apparatus concerning embodiment of this invention. It is a figure which shows typically the structure of the board | substrate for LED mounting of the display apparatus concerning embodiment of this invention. It is a figure which shows typically the wiring structure of the board | substrate for LED mounting of the display apparatus concerning embodiment of this invention. It is sectional drawing which shows typically the structure of the board | substrate for LED mounting of the display apparatus concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Backlight unit 110 Holder 120 Reflection sheet 130 Light guide plate 130a Light incident surface 140 Prism sheet 150 Diffusion sheet 160a-160d Light emitting diode 161a-161d Limiting resistor 170 LED mounting board 171a LED mounting part 171b Extension part 171c Terminal part 172a Anode Terminal 172b Cathode terminal 174 NC terminal 175 Wiring pattern 177 Land 179 Reinforcement plate 180 Adhesive material 190 Protection element 191 Mounting terminal 200 Liquid crystal display panel 210, 220 Transparent substrate 230 Drive circuit 240 Panel substrate 250 Connector 251 Mounting terminal

Claims (3)

A wiring board on which a wiring pattern is formed,
A light source mounted on a light source mounting portion of the wiring board;
A wiring pattern formed in an extended portion extending from the light source mounting portion of the wiring board, and electrically connected to the light source;
A terminal portion provided at an end of the extended portion of the wiring board, and a terminal connected to the light source through the wiring pattern;
A wiring board in which a protective element for protecting the light source is disposed on the terminal portion. In the terminal portion, a dummy connector terminal is provided between the terminals connected to the light source,
The wiring board according to claim 1, wherein the protection element is disposed in the vicinity of the dummy connector terminal. A display device comprising the wiring board according to claim 1.

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