JP2011186088A - Method for manufacturing liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method for determining a connection state between a shield layer and a product GND layer in a liquid crystal display device of a lateral electric field system. <P>SOLUTION: A shield layer 9 and a GND terminal 10 are connected to a determination circuit 13 to obtain a divided voltage potential. By determining whether the divided voltage potential is within the scope between an upper limit standard and a lower limit standard set by the determination circuit 13, it is inspected whether the resistance value between the shield layer 9 and the GND terminal is within the scope of a proper connection state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a lateral electric field type TFT liquid crystal display device in which a shield layer and a product GND are connected.

  A liquid crystal display device is widely used as a display function for a flat-screen TV, a mobile phone, and the like. In particular, mobile phones and the like are becoming more susceptible to the influence of external static electricity on the display surface of liquid crystal display devices as the mobile devices become lighter and thinner.

  In a liquid crystal display device, a TN method, a VA method, which generates an electric field in a vertical direction between a TFT substrate and a color filter substrate by sandwiching a liquid crystal layer between a pixel electrode on the TFT substrate side and a counter electrode on the color filter substrate side, MVA method etc. are mentioned. The TN method and VA method have the disadvantage that the image is easily negative-positive-inverted when viewed from an oblique direction. The MVA method has solved this drawback, but the MVA method does not function as a display unit in the pixel. There is a disadvantage that the transmittance and the aperture ratio become low.

  In order to solve these drawbacks, many liquid crystal display devices using a lateral electric field type TFT liquid crystal such as an IPS method or an FFS method for generating an electric field in a horizontal direction with respect to horizontally arranged liquid crystals have been put into practical use. A liquid crystal display device using a lateral electric field type TFT liquid crystal has a liquid crystal between an electrode substrate provided with a comb-like pixel electrode and a common electrode for generating an electric field between the pixel electrode and a counter substrate. Is sandwiched.

  In a horizontal electric field type liquid crystal display device, when an electric charge is applied to an opposing substrate on which an electrode is not provided due to external static electricity or the like, an unnecessary electric field is generated between the substrate on which an electrode is provided and the opposing substrate. This unnecessary electric field disturbs the alignment of the liquid crystal molecules contained in the liquid crystal, so that the liquid crystal display device cannot perform proper display.

  Therefore, a method is known in which an electrically shielded layer (hereinafter referred to as a shield layer) is formed on the surface of the counter substrate on which no electrode is provided to protect the liquid crystal display panel from the influence of unnecessary electric fields. Yes.

  In a horizontal electric field type liquid crystal display device, a blending characteristic of liquid crystal is disturbed, so that a shield layer cannot be provided on the inner surface of a substrate formed of glass. Therefore, a method of forming a shield layer on the surface of the substrate with a material such as ITO is generally used. In addition, by electrically connecting the shield layer and a GND terminal provided in an external circuit mounted on the board, the static electricity of the shield layer is discharged to GND, and the display quality of the liquid crystal display device is stabilized. Has been done.

  Here, in order to determine whether or not the shield layer and the GND terminal are reliably conducted, a probe is brought into contact with each of the shield layer and the GND terminal, and a current is passed from the probe brought into contact with the shield layer. A method is known in which the current is detected by a probe brought into contact with. (For example, refer to Patent Document 1.)

JP 2009-20272 A

  However, in the method of judging by passing a current between the shield layer and the GND terminal, it was confirmed only whether the current flowed in the connection circuit, and the connection state of the connection circuit such as disconnection or connection failure could not be confirmed. .

  Therefore, in the method of manufacturing the liquid crystal display device of the present invention, the shield layer formed on the surface of the counter substrate and the GND terminal provided in the external circuit connected to the substrate are connected to the determination circuit, respectively, and the shield layer and the GND are connected. Obtain the divided potential between the terminals. Then, an upper limit potential and a lower limit potential of the divided potential are set by the determination circuit, and it is determined whether the divided potential is within the range between the upper limit potential and the lower limit potential. If there is an abnormality in the resistance value indicating the connection state between the shield layer and the GND terminal, an abnormality is also detected in this divided potential, so that it is possible to check whether the shield layer and the GND terminal are properly connected.

  It is possible to determine not only whether the shield layer and the GND terminal are electrically connected, but also whether the connection state is appropriate.

It is a figure explaining the manufacturing method of the liquid crystal display device of this invention. It is sectional drawing which shows the structure of the liquid crystal display device of this invention typically. It is a figure which shows the determination circuit used for the manufacturing method of the liquid crystal display device of this invention.

  In the manufacturing method of the liquid crystal display device of the present invention, the GND terminal of the external circuit connected to the substrate and the shield layer formed on the surface of the counter substrate are electrically connected, and the shield layer and the GND terminal are appropriate. It is checked whether the connection is correct. This connection state can be confirmed by checking whether or not the resistance value between the shield layer and the GND terminal is within a normal connection range. It can also be confirmed by detecting an abnormality in the barometric potential. Therefore, in the manufacturing method of the present invention, the shield layer and the GND terminal are respectively connected to the connection terminal of the determination circuit, and a potential between the shield layer and the GND terminal (hereinafter referred to as a divided potential) is obtained by resistance voltage division. inspect.

  In the determination circuit, an upper limit potential and a lower limit potential that are standards are set, and it is determined whether or not the divided potential is within the range of each standard. In this way, it can be inspected whether the resistance value between the shield layer and the GND terminal is within a proper connection state range.

  In addition, the resistance value between the shield layer and the GND terminal at the time of normal connection is in a range from several ohms to several hundreds of kilohms depending on materials used.

A manufacturing method of the liquid crystal display device of this embodiment will be described with reference to the drawings.
FIG. 2 is a cross-sectional view schematically showing the liquid crystal display device 1 of the present invention. First, a liquid crystal display panel in which liquid crystal (not shown) is sandwiched between the substrate 5 and the counter substrate 4 is formed. Note that a horizontal electric field type TFT liquid crystal is used for the liquid crystal display panel of this embodiment. On the surface of the counter substrate 4, a conductive shield layer 9 having translucency such as ITO is formed by sputtering or spin coating. At this time, the shield layer 9 is formed in the pixel region of the liquid crystal display panel. A driving IC 7 and a circuit board 8 such as an FPC are mounted on the terminal portion on the surface of the board 4. The driving IC 7 may be flip-chip mounted (COG mounted) using ACF. Further, the circuit board 8 may be FOG-mounted using ACF.

  Further, the lower polarizing plate 6 is formed on the back surface of the substrate 5, and the upper polarizing plate 3 is formed on the surface of the counter substrate 4 via the shield layer 9. Here, the upper polarizing plate 3 is smaller than the shield layer 9 and is formed in the display area of the liquid crystal display panel. Therefore, as shown in FIG. 1, the shield layer 9 is exposed on the outer periphery of the liquid crystal display panel.

  Here, a conductive paste 2 such as silver paste or carbon is partially provided over the exposed surface of the shield layer 9 and the surface of the counter substrate 5. Thereby, the GND terminal 10 provided on the circuit board 8 and the shield layer 9 can be electrically connected, and external static electricity charged in the shield layer 9 can be discharged to the GND terminal 10.

  Next, the connection state between the shield layer 9 and the GND terminal 10 provided on the circuit board 8 is inspected. The determination circuit 13 is used for the inspection.

  First, as shown in FIG. 1, the second connection terminal 12 of the determination circuit 13 is brought into contact with the shield layer 9 of the liquid crystal display device 1 to be measured, and the first connection terminal 11 is brought into contact with the GND terminal 10. Probe needles can be used for the first connection terminal 11 and the second connection terminal 12. Then, the determination circuit 13 is used to check whether or not the resistance value RL between the connection terminals of the liquid crystal display element 10 generated between the first connection terminal 11 and the second connection terminal 12 is within a normal range.

  Next, the determination method will be described in detail with reference to FIG. FIG. 3 is a diagram showing the configuration of the determination circuit 13 of this embodiment. First, the voltage of the reference power supply 14 is divided by a resistance value of the voltage dividing resistor 15 and a resistance value between the first connection terminal and the second connection terminal (hereinafter referred to as a connection terminal resistance value RL). In this embodiment, the reference power supply 14 is accurately adjusted and set to a 5V voltage. Further, the potential of the second connection terminal 12 brought into contact with the GND terminal 10 is made common with the potential of the determination circuit side GND 16. In this embodiment, the value of the voltage dividing resistor 15 is 1 MΩ. Here, the divided potential generated at the connection terminal 11 in contact with the shield layer 9 includes the 5V voltage of the reference power supply 14 of the determination circuit 13, 1 MΩ of the voltage dividing resistor 15, and the resistance between the connection terminals of the liquid crystal display element 10. From the value RL, it becomes 5V × RLΩ / (1MΩ + RLΩ).

  In this embodiment, when the connection state between the shield layer 9 and the GND terminal 10 is good, the resistance value RL between the connection terminals is about 50 KΩ to 2 MΩ, and this value is the current standard (normal range). . However, when the wiring of the product is disconnected, or when the resistance value is abnormal due to connection failure or element failure, the connection terminal resistance RL shows an abnormal value. This abnormality of the connection terminal resistance RL is also detected as an abnormality of the divided potential. Therefore, it is determined whether the divided potential is within the standard range. The upper limit and the lower limit standard values can be obtained using the resistance value RL between the connection terminals when the connection state is good.

  The divided potential is determined on the upper limit side and the lower limit side. In the determination circuit 13, an upper limit potential and a lower limit potential that are standard for the divided potential are set by a variable resistor provided arbitrarily. As shown in the drawing, the upper limit determination comparator 19 determines the upper limit potential set by the upper limit variable resistor 17, and the lower limit determination comparator 20 determines the lower limit potential set by the lower limit variable resistor 18.

  By being connected to the comparator circuit in this way, when the divided potential is within the upper limit and lower limit standards, the output of each comparator becomes High level (5 V). When the divided potential exceeds the upper limit specification, the output of the upper limit determination comparator 19 becomes a low level (0 V). When the divided potential does not satisfy the lower limit standard, the output of the lower limit determination comparator 20 is at a low level (0 V). That is, if the divided potential is in the normal range, both comparator outputs are High, and the determination result 24 output from the AND gate that is the integrated determination gate 21 is High. And since the electric current value prescribed | regulated by LED current limiting resistance 22 flows into LED23 and LED23 lights, it turns out that a connection state is favorable by visual determination.

  On the other hand, when the divided potential is an abnormal value, the output of either the upper limit determination comparator 19 or the lower limit determination comparator 20 is Low. Therefore, the determination result 24 output from the AND gate that is the integrated determination gate 21 is Low. In this case, the LED 23 is not turned on, and it can be seen from the visual determination that the connection state is poor.

  Further, the determination result 24 may be taken into another display inspection device or the like, and not only visual determination but also automatic defect detection may be performed.

  Note that conductive rubber, a conductive sheet, or a zipper tube may be used instead of the probe needle for the connection terminal of the determination circuit. By using the connection terminal made of such a material, it is possible to prevent the polarizing plate and the liquid crystal panel substrate from being damaged.

  Further, the shield layer and the GND terminal may be connected by a tape made of a conductive material such as metal or carbon.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Conductive paste 3 Upper polarizing plate 4 Opposite substrate 5 Substrate 6 Lower polarizing plate 7 IC
8 Circuit board 9 Shield layer 10 GND terminal 11 First connection terminal 12 Second connection terminal 13 Judgment circuit 14 Reference power supply 15 Resistance for voltage division 16 Judgment circuit side GND
17 Upper Limit Variable Resistor 18 Lower Limit Variable Resistor 19 Upper Limit Determination Comparator 20 Lower Limit Determination Comparator 21 Integrated Determination Gate 22 LED Current Limiting Resistor 23 LED
24 judgment results

Claims (3)

In a method of manufacturing a lateral electric field type liquid crystal display device in which a GND terminal of an external circuit connected to a substrate and a shield layer formed on the surface of a counter substrate are electrically connected.
A connection state between the shield layer and the GND terminal by connecting the shield layer and the GND terminal to a determination circuit and determining whether a divided potential between the shield layer and the GND terminal is within a standard range. Of manufacturing a liquid crystal display device. The shield layer is connected to a first connection terminal of the determination circuit, and the GND terminal is connected to a second connection terminal of the determination circuit;
The potential of the second connection terminal is common to the GND potential of the determination circuit, and
The divided voltage potential is a voltage obtained by dividing a voltage of a reference power source of the determination circuit with a voltage dividing resistor and a resistance between the first connection terminal and the second connection terminal. 2. A method for producing a liquid crystal display device according to 1. In the determination circuit, an upper limit potential and a lower limit potential are set by a variable resistor,
3. The method of manufacturing a liquid crystal display device according to claim 1, wherein it is determined whether the divided potential is in a range between the upper limit potential and the lower limit potential.

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