JP4618034B2 - Liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device having a self-diagnosis function, and more particularly to a liquid crystal display device having a self-diagnosis mode using a diagnostic VCOM signal applied to a counter electrode.

  The liquid crystal display panel has a configuration in which two transparent substrates on which electrodes or the like are formed face each other, the periphery of the transparent substrate is fixed with a sealing material, and liquid crystal is sealed in a space formed by the transparent substrate and the sealing material. Have. For example, in the case of an active matrix liquid crystal display panel, signal lines and scanning lines are arranged in a matrix on one substrate, thin film transistors are formed at the intersections, and the thin film transistors are connected in the region surrounded by the signal lines and scanning lines. The pixel electrode to be formed is formed. A portion where the pixel electrode is formed becomes a display region. Also, on the other substrate, one of R, G, and B filter layers is disposed at a position facing the pixel electrode, a black matrix is provided between the filter layers, and the filter layer and the black matrix are made of transparent electrodes. Covered by the counter electrode.

  For example, in the case of a small-sized liquid crystal display panel for a mobile phone, a driver IC is placed on one end of a frame portion provided around the display area of one substrate, and the counter IC generated in the driver IC. A VCOM signal applied to the electrodes is output to the common line. In the case of a medium or large liquid crystal display panel, the VCOM signal is generated by a counter electrode drive circuit unit on a printed circuit board and connected to a common line through a flexible wiring board.

  Also, one substrate is provided with a transfer electrode connected to the driver IC via a common line, and this transfer electrode is electrically connected to the opposite electrode of the other substrate via a conductive member. A predetermined VCOM signal is supplied from the IC to the counter electrode via the common line and the transfer electrode.

  On the substrate, for example, a sealant mainly composed of a photocurable resin or a thermosetting resin is applied in a predetermined pattern, and the two substrates are bonded to each other. In Patent Documents 1 to 3 below, a resin used as a sealing material for the transfer electrode is mixed with a granular conductor, and the counter electrode and the transfer electrode are formed by the granular conductor. An electrical connection is disclosed.

  A specific example of such a liquid crystal display panel will be described with reference to FIGS. 3 is a plan view schematically showing the first substrate side of a small-sized liquid crystal display device for a mobile phone, FIG. 4 is a cross-sectional view schematically showing the arrangement of a sealing material and a contact material, and FIG. 5 is opposed to the transfer electrode. It is a principal part enlarged view which shows the connection state of an electrode typically.

  In the first substrate 11 made of a transparent substrate of the liquid crystal display device 10A, scanning lines and signal lines are formed in a matrix in the display area 12, and pixel electrodes are formed in portions surrounded by the scanning lines and the signal lines. A thin film transistor as a switching element connected to the pixel electrode is formed at the intersection of the line and the signal line. Although specific configurations of these wirings, thin film transistors, and pixel electrodes are not shown, these are schematically shown as the first structure 13 in FIG.

  A flexible wiring substrate 14 for connecting to an image supply device (not shown) for driving the liquid crystal display device 10A is pressure-bonded to the short side portion of the first substrate 11 by ACF (Anisotropic Conductive Film). This flexible wiring board 14 connects data lines and control lines from the image supply apparatus to the driver IC 15. In the case of a medium-sized or large-sized liquid crystal display panel, most of the functions mounted on the mobile phone driver IC are mounted on the printed circuit board, and in particular, the VCOM signal is generated by the counter electrode drive circuit unit, and the driver IC is mounted. It is connected to the common line through the flexible wiring board.

A plurality of transfer electrodes 17 _{1 to} 17 ₄ are provided at the four corners of the first substrate 11. The transfer electrodes 17 _{1 to} 17 ₄ are formed in the same process as the process of forming the scanning lines and the like, and are made of the same material as the scanning lines. The transfer electrodes 17 ₁ to 17 ₄ are adapted to the same potential are connected to one another directly connected or in the driver IC15 each other through a common line 16 _C. The transfer electrodes ₁₇ 1 to 17 ₄ are connected to the counter electrode 18 and electrically to be described later, a predetermined voltage VCOM is adapted to be applied to the counter electrode 18 that is output from the driver IC 15. In some cases, the arrangement of the gate lines 16 _G and the source lines 16 _S reversed. In addition, the driver IC 15 may be disposed on the long side instead of only on the short side.

  A color filter and a black matrix are formed on the second substrate 19 made of a transparent substrate. The color filter is disposed so as to face the pixel electrode of the first substrate 11 and a filter layer corresponding to each pixel is provided. The black matrix is disposed at a position corresponding to at least the scanning line and the signal line of the first substrate 11. Has been. Although a specific configuration of these color filters and the like is not shown, these are schematically shown as the second structure 20 in FIG.

  On the second substrate 19, a counter electrode 18 made of a transparent electrode made of indium oxide, tin oxide or the like is further formed over at least the entire display region 12.

Sealing material 21, the periphery of the display area 12 of the first substrate 11 are coated with the exception of the inlet (not shown), also the contact member 17 is coated on the transfer electrode 17 _{1-17 4} . As shown in FIG. 5, the sealing material 21 is obtained by mixing a filler 24 of insulating particles into a thermosetting resin 23 such as an epoxy resin, and the contact material 17 is made of the same resin as the sealing material. A granular conductor 25 is mixed therein.

As the granular conductor 25 mixed in the contact material 17, for example, a spherical conductive resin particle plated with a flexible conductive metal such as Au can be used, and the particle diameter is larger than the cell gap of the liquid crystal display panel. Slightly larger about 6 μm. Without a gap between the granular conductor 25 the transfer electrodes 17 ₁ to 17 ₄ and the counter electrode 18 when bonding the two substrates 11 and 19 if so, granular conductor 25 is reliably transfer electrodes 17 _{1 to} 17 ₄ and the counter electrode 18 are contacted.

  The filler 24 is mixed with the sealing material 21 or the contact material 17 in order to prevent the deformation of the filler 24 when applied, and is made of alumina or silica having a particle size of about 1 μm.

When the substrates 11 and 19 are bonded together, the following procedure is performed. First, the first substrate 11 is set in the first dispenser device and the sealing material 21 is applied in a predetermined pattern, and then the first substrate 11 is set in the second dispenser device and the contact material 17 is transferred to the transfer electrode 17 _1. It is coated on to 17 _4. Thereafter, spacers 27 are evenly spread over the display area 12 of the first substrate 11, and a temporary fixing adhesive is applied to the portion of the second substrate 19 where the sealing material 21 and the contact material 17 come into contact. Thereafter, the first substrate 11 and the second substrate 19 are bonded together, and the temporary fixing adhesive is cured to complete the temporary fixing. When both the temporarily fixed substrates 11 and 19 are heat-treated, the thermosetting resin of the sealing material 21 and the contact material 17 is cured, and an empty liquid crystal display panel is completed. Liquid crystal 28 is injected into the empty liquid crystal display panel from an injection port (not shown), and the injection port is closed with a sealant, thereby completing the liquid crystal display device 10A.
JP 2002-090770 A (claims, paragraphs [0002] to [0004], [0016] to [0027], FIGS. 1 to 3) JP-A-8-179348 (Claims, FIGS. 1 and 2) JP-A-10-186395 (Claims, FIG. 1)

In such a portable liquid crystal display panel, VCOM signal from the driver IC 15 ACF crimping portion, the common line 16 _C, applied to the counter electrode 18 via the transfer electrodes ₁₇ 1 to 17 _4, also of medium-sized or large-sized for the liquid crystal display panel, VCOM signal via a flexible wiring board from the external circuit board, ACF compression bonding portion is supplied to the counter electrode 18 through the common line 16 _C, the transfer electrodes ₁₇ 1 to 17 _4.

A rectangular wave is usually used for the VCOM signal of the line inversion driving method or the frame inversion driving method. This is for the purpose of reducing the cost by lowering the voltage of the VCOM signal. As described above, VCOM signal, ACF crimping portion, the common line 16 _C, but applied to the counter electrode 18 via the transfer electrodes ₁₇ 1 to 17 _4, these ACF crimping portion, the common line 16 _C, transfer electrodes 17 When _one resistor in to 17 ₄ is large, VCOM signal applied to the counter electrode 18 would dull the waveform. When the waveform of the VCOM signal is dull, problems such as crosstalk occur.

Therefore, in the conventional liquid crystal display panel, to reduce the connection resistance between the common line 16 _C and the counter electrode 18 as much as possible, the transfer electrodes plurality of locations (e.g., four positions) are arranged. However, due to structural problems such as transfer electrodes, a liquid crystal display device that does not have a satisfactory resistance value when a liquid crystal display panel is mass-produced may be obtained.

  Therefore, the present invention can discriminate a liquid crystal display device having a large connection resistance due to the resistance of the ACF crimping portion, the VCOM wiring resistance, the transfer electrode, etc. with a simple configuration and operation in order to cope with such problems of the conventional technology. An object is to provide a liquid crystal display device having a self-diagnosis mode.

  The above object of the present invention can be achieved by the following configurations. That is, the invention of the liquid crystal display device according to claim 1 includes a plurality of transfer electrodes provided in a frame portion around the display area and a plurality of common wirings respectively connected to the plurality of transfer electrodes. In a liquid crystal display device including a liquid crystal display panel having a first substrate and a second substrate on which a common electrode electrically connected to the plurality of transfer electrodes of the first substrate is formed, the plurality of the plurality of substrates in a normal operation mode. A common VCOM signal is output to the common wiring of the first and, in the self-diagnosis mode, a predetermined diagnostic VCOM signal is output to one of the plurality of common wirings, and a signal appears on at least one other common wiring. And the magnitude of the connection resistance between the two common wires is determined by comparing the diagnostic VCOM signal with the signal appearing on the common wire. Characterized by comprising ourselves diagnostic means.

  According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect, the self-diagnosis means is provided on a printed circuit board connected to the liquid crystal display panel.

  According to a third aspect of the present invention, in the liquid crystal display device according to the first aspect, the self-diagnosis means is built in a driver IC mounted on the frame portion.

  According to a fourth aspect of the present invention, in the liquid crystal display device according to the third aspect, the driver IC includes a pair of VCOM signal output terminals respectively connected to the plurality of common lines at both ends, and in a normal operation mode. A common VCOM signal is output to the pair of VCOM signal output terminals, the diagnostic VCOM signal is output to one of the VCOM signal output terminals in the self-diagnosis mode, and the other at least one of the other VCOM signal output terminals is the other VCOM signal output terminal. Signals appearing on two common wires are input.

  Further, the invention according to claim 5 is the liquid crystal display device according to any one of claims 1 to 4, wherein the self-diagnosis means includes a storage means for storing a threshold value of the connection resistance between the two common lines inputted in advance; Storage means for storing the diagnosis result.

  By providing the above-described configuration, the present invention has the following excellent effects. That is, according to the first aspect of the present invention, in the self-diagnosis mode, a predetermined diagnostic VCOM signal applied to one of the plurality of common wires is transferred from the common wire to the transfer electrode, the common electrode, and the other transfer wires. Since it is sequentially transmitted to the electrode and other common wiring, if there is a part with high resistance in the middle of this transmission path, the waveform of the diagnostic VCOM signal is dull, so that a signal appearing on at least one other common wiring is detected. By doing so, it is possible to detect whether or not there is a portion having a large resistance in the middle of the transmission path. Thereby, it becomes possible to easily discriminate a liquid crystal display device having a large connection resistance due to the VCOM wiring resistance, the transfer electrode, or the like.

  According to the second aspect of the present invention, since the various signal input terminals of the liquid crystal display panel are normally electrically connected by ACF crimping via the printed circuit board and the flexible wiring board, the VCOM wiring resistance and the transfer electrode are used. A liquid crystal display device having a large connection resistance that takes into account not only the connection resistance but also the resistance of the ACF crimping portion between the printed circuit board and the input terminal can be discriminated.

  According to the third aspect of the present invention, since the self-diagnosis means is built in the driver IC provided in the liquid crystal display panel, the self-diagnosis mode is set by simply giving a self-diagnosis switching signal to the driver IC. To discriminate a liquid crystal display device that can be switched and has a large connection resistance in consideration of not only the connection resistance due to the VCOM wiring resistance and the transfer electrode but also the resistance of the ACF crimping portion between the driver IC and the common wiring. Will be able to.

  According to the invention of claim 4, since the transfer electrode is usually provided to be as diagonal as possible of the liquid crystal display panel, the VCOM signal output terminal connected to the common wiring at each end as a driver IC is provided. By using what is provided, in the self-diagnosis mode, the VCOM signal output terminal on one end side can be easily used as the diagnostic VCOM signal output terminal, and the VCOM signal output terminal on the other end side can be used as at least one other common wiring. Therefore, it is not necessary to provide a special wiring especially for self-diagnosis.

  According to the invention of claim 5, the threshold value of the connection resistance between the two common wirings can be appropriately set and stored in the driver IC according to the size or type of the liquid crystal display panel, and the diagnosis result is stored in the driver IC. Since the data is stored, it is possible to automatically classify the diagnosis results that are “impossible” by reading the diagnosis results during the manufacturing process of the liquid crystal display device.

The best mode for carrying out the present invention will be described in detail below with reference to FIGS. 1 to 2. The embodiment described below is a liquid crystal display device for embodying the technical idea of the present invention. It is an example, and is not intended to specify the present invention in this embodiment, and the present invention has been variously modified without departing from the technical idea shown in the claims. It can be applied equally. FIG. 1 is a block diagram showing a schematic configuration of the liquid crystal display device of the embodiment, and FIG. 2 is a block diagram showing a schematic configuration of the counter electrode drive circuit unit of FIG. 1, shown in FIGS. The same components as those in the conventional liquid crystal display device 10A will be described with the same reference numerals.

  The liquid crystal display device 10 of this embodiment has the same configuration as the conventional liquid crystal display device 10A shown in FIGS. 3 to 5, but is connected to the internal configuration of the driver IC and the common electrode of the liquid crystal display panel. Common wiring parts are different.

  That is, the liquid crystal display device 10 of this embodiment includes a driver IC 15 and a liquid crystal display panel 31, and the driver IC 15 includes a signal control circuit unit 32, a power supply circuit unit 33, a γ correction gradation voltage circuit unit 34, The counter electrode drive circuit unit 35, the data line drive circuit unit 36, and the address line drive circuit unit 37 are integrally provided, and the common electrode of the liquid crystal display panel 31 is VCOM1 which is a separate common line through different transfer electrodes. The wiring and the VCOM2 wiring are connected to the counter electrode driving circuit unit 35 of the driver IC 15. It should be noted that the number of each transfer electrode here does not necessarily mean one, but may be plural.

  The signal control circuit unit 32 is sent from an image supply device, for example, an image creation unit of a mobile phone, a computer, a television device, a video playback device, a DVD (Digital Versatile Disk) playback device, etc. via an input interface (not shown). The data enable signal DE, the digital pixel data IRD, IGD, IBD, and other image data signals, and the clock signal DOTCL, the vertical synchronization signal VSYN, the horizontal synchronization signal HSYN, and the like are digitally processed. The digital RGB output signals DR, DG, and DB are supplied to the data line drive circuit unit 36, the clock pulse CPV is supplied to the power supply circuit unit 33, the counter electrode drive circuit unit 35, and the address line drive circuit unit 37, and the frame signal ( A start pulse (FLM) is also supplied to the address line drive circuit unit 37.

The power supply circuit unit 33 uses various voltages used in the liquid crystal display device 10 based on the supplied power supply voltage VIN (for example, 12V), for example, the signal control circuit unit 32, the counter electrode drive circuit unit 35, data The driving voltage VDD of the line driving circuit unit 36 and the address line driving circuit unit 37, the reference voltage V ₀ supplied to the gradation voltage circuit unit 34, and the column line 38 of the liquid crystal display panel 31 via the data line driving circuit unit 36. The voltage VGEN to be applied and the voltages VGH and VGL to be applied to the row line 39 of the liquid crystal display panel 31 through the address line drive circuit unit 37 are generated.

The gradation voltage circuit unit 34 generates a plurality of gradation reference voltages VGM by resistance-dividing the reference voltage V ₀ supplied from the power supply circuit unit 33 and supplies the gradation reference voltage VGM to the data line driving circuit unit 36. The drive circuit unit 36 processes the digital RGB output signals DR, DG, and DB by using the plurality of gradation reference voltages VGM as reference voltages for the built-in DA converter circuit, thereby liquid crystal display panel 31. Γ-corrected analog image data signal is supplied to the column line 38.

  Further, as shown in FIG. 2, the counter electrode drive circuit unit 35 switches the counter electrode drive circuit unit 35 between a self-diagnosis mode and a normal operation mode in response to a self-diagnosis switching signal input from the outside. Unit 40, a VCOM signal generating unit 41 that generates the same VCOM signal as in the conventional mode in the normal operation mode, a diagnostic signal generating unit 42 that generates a diagnostic VCOM signal used in the self-diagnosis mode, and a diagnostic threshold value input from the outside The threshold value storage unit 43 that stores a threshold value of resistance between both common wires including the resistance of the ACF crimping unit set in advance by a signal is compared with the VCOM signal for diagnosis and the signal appearing at the VCOM1 terminal 44 to compare the connection resistance. The resistance calculation unit 45 for calculating the resistance, and the output of the resistance calculation unit 45 is compared with the output of the resistance calculation unit 45 and the threshold value of the connection resistance stored in the threshold value storage unit 43. And determining the resistance comparing unit 46 small, and a diagnosis result storage unit 47 which the output of the resistance comparison unit 46 stores and outputs the diagnosis result signal to the outside in response to an external request.

  The diagnostic SW unit 40, the VCOM signal creation unit 41, the threshold storage unit 43, the resistance calculation unit 45, the resistance comparison unit 46, the diagnostic result calculation unit 47, the VCOM1 terminal 44, and the VCOM2 terminal 48 are an inverter 49, a buffer 50, and 51 and 3-state gates 52-54 are connected as shown in FIG.

  That is, in the normal operation mode, the diagnosis SW unit 40 outputs an H level, the three-state gate 53 is turned off, and the three-state gates 52 and 54 are turned on. The same VCOM signal as before is output to the VCOM1 terminal 44 through the three-state gates 52 and 54, and simultaneously to the VCOM2 terminal 48 through the three-state gate 52 and the buffer 51, and this VCOM signal is separately supplied to the liquid crystal display panel 31. Are simultaneously applied to the common electrode via the VCOM1 wiring and the VCOM2 wiring which are common wirings.

  On the other hand, in the self-diagnosis mode, the L level is output from the diagnosis SW unit 40, the 3-state gate 53 is turned on, and the 3-state gates 52 and 54 are turned off. The conventional VCOM signal is blocked by the three-state gate 52, and the diagnostic VCOM signal created by the diagnostic signal creation unit 42 is applied to the resistance calculation unit 45 via the three-state gate 53, and also through the buffer 51 to the VCOM2 It is output to the terminal 48. At this time, since the three-state gate 54 is in the OFF state, the diagnostic VCOM signal is not applied to the VCOM1 terminal 44.

  The diagnostic VCOM2 signal output to the VCOM2 terminal 48 is supplied to the common electrode via the VCOM2 wiring that is one common wiring of the liquid crystal display panel 31, and the common electrode is a VCOM1 wiring that is another common wiring. The signal appearing at the VCOM1 terminal 44 is input to the resistance calculation unit 45 via the buffer 50. The signals appearing at the VCOM1 terminal 44 are the VCOM2 terminal 48, the ACF crimping portion, the VCOM2 wiring that is one common wiring of the liquid crystal display panel 31, one transfer electrode, the common electrode, another transfer electrode, and another common wiring. Since it appears to the VCOM1 terminal 44 through the VCOM1 wiring and the ACF crimping part, if there is a part having a large resistance or disconnection in one place of these paths, the signal appearing on the VCOM1 terminal 44 is a signal in which the diagnostic VCOM2 signal is dull. . Therefore, since the output in the resistance calculation unit 45 is a value representing the resistance value in the path, this value is compared with the threshold value stored in the threshold storage unit 43 in advance, and if the resistance value in the path is smaller than the threshold value, the non-defective product is obtained. If it is greater than the threshold value, it is determined as a defective product, and the diagnosis result is stored in the diagnosis result storage unit 47.

  If the diagnostic result stored in the diagnostic result storage unit 47 is read during the manufacturing process of the liquid crystal display device, it can be determined whether the liquid crystal display device is a good product or a defective product. A non-defective liquid crystal display device can be discriminated.

  In this embodiment, the liquid crystal display device 10 in which the driver IC 15 is mounted on the liquid crystal display panel has been described. However, the liquid crystal display in which the driver IC is mounted on an external circuit board (not shown) different from the liquid crystal display panel. It can also be applied to a device.

  In this embodiment, the signal related to the diagnosis is directly input / output to / from the outside. However, a register is arranged in the driver, and an address and data are connected between the image supply device and the driver 15 as in, for example, a CPU interface. For example, information may be exchanged.

FIG. 1 is a block diagram illustrating a schematic configuration of a liquid crystal display device according to an embodiment. FIG. 2 is a block diagram showing a schematic configuration of the counter electrode drive circuit unit of FIG. FIG. 3 is a plan view schematically showing a first substrate side of a small-sized liquid crystal display device for a mobile phone. FIG. 4 is a cross-sectional view schematically showing the arrangement of the sealing material and the contact material. FIG. 5 is an enlarged view of a main part schematically showing a connection state between the transfer electrode and the counter electrode.

Explanation of symbols

10 Liquid crystal display device 15 Driver IC
31 Liquid crystal display panel 32 Signal control circuit unit 33 Power supply circuit unit 34 Gamma correction gradation voltage circuit unit 35 Counter electrode drive circuit unit 36 Data line drive circuit unit 37 Address line drive circuit unit 40 Diagnostic SW unit 41 VCOM signal creation unit 42 Diagnostic signal creation unit 43 Threshold storage unit 44 VCOM1 terminal 45 Resistance calculation unit 46 Resistance comparison unit 47 Diagnostic result storage unit 48 VCOM2 terminal 49 Inverter 50, 51 Buffers 52-54 Three-state gate

Claims (5)

A first substrate having a plurality of transfer electrodes provided in a frame portion around the display area and a plurality of common wirings respectively connected to the plurality of transfer electrodes; and a plurality of transfer of the first substrate In a liquid crystal display device including a liquid crystal display panel having a second substrate on which a common electrode electrically connected to the electrode is formed, a common VCOM signal is output to the plurality of common wires in a normal operation mode, In the diagnosis mode, a predetermined diagnostic VCOM signal is output to one of the plurality of common wirings, and a signal appearing in at least one other common wiring is detected, and the diagnostic VCOM signal and the common wiring are detected. A self-diagnostic means is provided for determining the magnitude of the connection resistance between the two common wires by comparing the signal appearing on the liquid crystal display. Apparatus. The liquid crystal display device according to claim 1, wherein the self-diagnosis unit is provided on a printed circuit board connected to the liquid crystal display panel. The liquid crystal display device according to claim 1, wherein the self-diagnosis unit is built in a driver IC mounted on the frame portion. The driver IC includes a pair of VCOM signal output terminals connected to the plurality of common wires at both ends, outputs a common VCOM signal to the pair of VCOM signal output terminals in a normal operation mode, and in a self-diagnosis mode. 4. The diagnostic VCOM signal is output to one of the VCOM signal output terminals, and a signal appearing on the at least one other common wiring is input to the other of the VCOM signal output terminals. The liquid crystal display device described. 5. The self-diagnosis unit includes a storage unit that stores a threshold value of a connection resistance between the two common wirings that is input in advance, and a storage unit that stores the diagnosis result. A liquid crystal display device according to claim 1.

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