JP4811202B2 - Reflective liquid crystal display - Google Patents

Description

  The present invention relates to a reflective active matrix liquid crystal display device suitable for a projection liquid crystal display or the like.

  In recent years, in parallel with technological progress in computers, communications, broadcasting, information recording media, etc., there has been an increasing demand for displays that display such video information on a large screen with high definition. Projection-type liquid crystal displays have already been put to practical use to achieve this. Projection type liquid crystal displays are roughly classified into a transmission type and a reflection type (for example, Patent Documents 1 to 3).

  The former is a system in which a liquid crystal panel in which pixels made up of thin film transistors and light transmissive electrodes are arranged in a matrix on a transmissive insulating substrate is used, and the light transmitted through the liquid crystal panel is modulated and displayed by liquid crystal for each pixel. The transmissive type has the advantage that the configuration of the optical system for projecting light can be made relatively simple, but if the liquid crystal panel is downsized and the pixel density is increased, the ratio of the transistor and the wiring portion to the pixel area is increased. There is a problem that the aperture ratio increases and the aperture ratio decreases. In addition, since the aperture structure of the pixels is clearly displayed in the projected image, there is a drawback that the smoothness at the video boundary is lacking particularly when a natural image is displayed.

  On the other hand, in the latter reflection type, each pixel is composed of a reflection type pixel electrode, and all the transistors and wiring can be arranged under the reflection type pixel electrode, so that a high pixel density without reducing the aperture ratio. Can be realized. Further, since the gap between the pixel electrodes formed in each pixel can be very small as 0.3 to 0.6 μm, the pixel opening structure is not conspicuous, and a smooth image can be displayed. From the above, it can be said that the reflective type capable of miniaturization and high definition is suitable for application to a projection type liquid crystal display requiring high definition display.

A basic configuration example of a conventional reflective liquid crystal display device used for a liquid crystal display or the like will be described with reference to FIGS. FIG. 10 is a diagram showing an outline of a drive circuit formed on the drive circuit board of the liquid crystal display device.
As shown in FIG. 10, in this liquid crystal display device, a horizontal scanning driving circuit 2 is formed on one side and a vertical scanning driving circuit 4 is formed on the other side on a driving circuit substrate serving as a first substrate. The A plurality of signal electrodes D1,... Dm (m: positive number) extend from the horizontal scanning drive circuit 2, and a plurality of selection signal electrodes G1,... Gn (n: positive number) extend from the vertical scanning drive circuit 4. The display pixels Px are arranged at the intersections of these two signal electrodes. Therefore, the display pixels Px are arranged in a matrix form vertically and horizontally. In the illustrated example, four display pixels Px are shown as representatives, but in reality, a large number of display pixels are provided. The reflective pixel electrodes 500 are also arranged in a matrix in the vertical and horizontal directions corresponding to the display pixels Px.

The horizontal scanning drive circuit 2 is composed of a shift register circuit and a sampling switch group (not shown) controlled to be turned on / off by the output of the shift register circuit. The horizontal scanning drive circuit 2 receives a horizontal synchronization signal Hst, a clock signal Hck, and a display signal Video. By inputting, the display signal is sequentially sampled and supplied to the signal electrodes D1,.
The vertical scanning drive circuit 4 is composed of a shift register circuit (not shown), and sequentially receives a vertical synchronizing signal Vst and a clock signal Vck for each selection signal electrode G1,. Supply a selection signal. In the following description, the signal electrodes D1,... Dm may be represented as “D”, and the selection signal electrodes G1,.

  The display pixel Px includes, for example, a transistor switch Tr made of a MOS transistor, a signal storage holding capacitor Cs, and a pixel electrode 500. Here, the transistor switch Tr and the storage capacitor Cs form a switching circuit Sw. The signal electrode D is connected to one main terminal, for example, the drain of the transistor switch Tr, the pixel electrode 500 is connected to the other main terminal, for example, the source, and the selection signal electrode G is further connected to the control terminal (gate). Is connected.

  A second substrate 12 (see FIG. 12), which is a transparent substrate on which the counter electrode 13 formed in common for each pixel is formed via the liquid crystal LC, is disposed at the opposing portion of the pixel electrode 500. A selection signal is supplied from the vertical scanning drive circuit 4 to the control terminal of the transistor switch Tr constituting the display pixel Px, and the transistor switches Tr for one row are sequentially turned on and selected in one horizontal period. In each display pixel Px, the display signal of the signal electrode D is written into the storage capacitor Cs. This voltage is held in the holding capacitor Cs during a non-selection period until a new display signal is written in the next vertical scanning period, and the liquid crystal LC corresponding to each display pixel Px is driven with a voltage corresponding to the display signal.

  In the reflective liquid crystal display device, the drive circuit substrate which is the first substrate does not need transparency, and a general semiconductor substrate typified by a silicon substrate can be used. In addition, since a semiconductor element such as a transistor can be formed on a silicon substrate, transistor characteristics excellent in off-leakage and current-voltage characteristics can be realized. Further, not only the display pixel Px but also the horizontal scanning driving circuit 2 and the vertical scanning driving circuit 4 are driven. The circuit can be easily configured on the same substrate.

11 and 12 are a plan view and a cross-sectional view showing a typical structure example of a display pixel of a general reflection type liquid crystal display device. As shown in the figure, a transistor region 15 and a storage capacitor region 16 are disposed on a well 100 formed on the surface of a first substrate 11 made of a silicon substrate. A switching transistor Tr is formed in the transistor region 15, and a storage capacitor Cs is formed in the storage capacitor region 16. The transistor switches Tr and the storage capacitors Cs between the display pixels Px and the display pixels Px are separated from each other by the field oxide film 112. The gate 102 of the transistor switch Tr and the storage capacitor electrode 105 of the storage capacitor Cs are formed of a polysilicon wiring layer and have a so-called MIS structure in which SiO ₂ is an insulating layer between the silicon substrates.

  The column signal electrode 101 (corresponding to D in FIG. 10) is wired with a first metal layer formed above the polysilicon wiring layer via an insulating layer, and the drain diffusion of the transistor switch Tr via the contact hole. It is electrically connected to region 140. A relay electrode 104 formed in the first metal layer is connected to the source diffusion region 103 which is the other terminal of the transistor switch Tr through a contact hole, and the relay electrode 104 further contacts the storage capacitor electrode 105. Connected through halls. A high-concentration diffusion layer 110 is formed on the silicon substrate side of the storage capacitor region 16 and is commonly wired by the wiring 111 (Com) formed in the first metal layer.

  Here, the relay electrode 104 of the first metal layer is formed so as to completely cover the source diffusion region 103 of the transistor switch Tr. As described above, the relay electrode 104 covers the source diffusion region 103 of the transistor switch Tr and shields against leakage light, thereby preventing the generation of optical carriers in the semiconductor structure formed by the source-well. Stable signal holding characteristics and display characteristics can be obtained even under strong light irradiation.

  Further, here, the uppermost layer of the first metal layer and the reflective pixel electrode 500 is formed so that sufficient light resistance can be ensured even against extremely strong light irradiation (incident light). The light shielding pattern 106 is formed of a metal layer located in the lower layer of the upper layer. A relay pattern 1002 separated by the opening 107 is formed in the light shielding pattern 106, and the uppermost pixel electrode 500 and the relay electrode 104 serving as a source wiring of the transistor switch Tr are contact holes, and the relay pattern 1002 and the contact holes are formed. Connected through. Thereby, the source diffusion region 103 of the transistor switch Tr and the pixel electrode 500 are connected.

  The insulating layer 120 under the pixel electrode 500 is polished so that the surface thereof becomes flat at an optical level in a pre-process for forming the pixel electrode 500. As the surface polishing means for realizing such flatness, for example, a CMP method (Chemical-Mechanical Polish) for chemically and mechanically polishing a member layer can be applied.

Further, a planarization layer 130 for filling a mechanical step is formed in a gap between adjacent pixel electrodes 500. Thereby, the disorder of the liquid crystal alignment due to the stepped portion and the occurrence of optical scattering can be suppressed, and the display contrast can be prevented from being lowered. As a process for filling the gap between the pixel electrodes, for example, after the pixel electrode 500 is formed, an insulating layer such as SiO ₂ is uniformly deposited on the surface of the pixel electrode 500, and then this is continued until the surface of the pixel electrode is exposed. An etch back method of etching can be used. Note that a light absorption layer for suppressing multiple reflection of light on the metal layer may be formed on the front and back surfaces of the light shielding pattern 106 or the back surface of the pixel electrode 500 as necessary.

An alignment film 152b for aligning the initial molecular arrangement of the liquid crystal material in a predetermined direction is formed on the entire upper surface of each pixel electrode 500. Further, the same alignment layer 152a is formed on the entire lower surface side of the counter electrode 13 (corresponding to CE in FIG. 10) formed on the light-transmitting second substrate 12. A liquid crystal 151 (corresponding to LC in FIG. 10) is sealed between the first substrate 11 and the light transmissive second substrate 12 so that the alignment layers 152b and 152a face each other. The state of incident light is modulated according to the signal voltage of the electrode 500.
An example of a liquid crystal display mode suitable for a reflective liquid crystal display device is a field effect birefringence mode. 13 and 14 show an example of a normally black liquid crystal using a liquid crystal having negative dielectric anisotropy and having an initial alignment substantially perpendicular to the substrate.

As shown in FIG. 13, under the condition where no voltage is applied, the alignment direction of the liquid crystal molecules M is substantially perpendicular to the substrates E1 and E2 and slightly inclined in a constant direction. The reason for imparting slight constant slope in the initial alignment is for the purpose of controlling such that the liquid crystal molecules when a voltage is applied tilts aligned in a predetermined direction, the specific orientation film forming means as the SiO ₂ oblique vapor deposition The following means can be used. In this case, since the birefringence action does not appear with respect to the linearly polarized light PI incident from the polarization beam splitter PBS, the polarization direction of the output light P3 reflected by the pixel electrode is the same linear polarization as the polarization direction of the incident light P1. Therefore, when the output light P3 passes through the polarization beam splitter PBS again, it is reflected to the light source side (PO), and black is displayed on the projection screen.

  On the other hand, FIG. 14 shows a state in which the voltage V is applied to the liquid crystal, and the liquid crystal molecules M are inclined in a certain direction with respect to the substrate. Due to the birefringence based on the difference in refractive index between the major axis and the minor axis of the liquid crystal molecule M, a change occurs in the phase difference with respect to the orthogonal polarization component of the light, and the polarization state of the output light P3 is a molecular inclination corresponding to the applied voltage, Depending on the total optical path length corresponding to the liquid crystal gap and the retardation value with the wavelength of the incident light P1 as a parameter, the polarization changes from elliptically polarized light to circularly polarized light, and further linearly polarized light in the polarization direction orthogonal to the incident light P1. The polarization component orthogonal to the incident light P1 is incident on the polarization beam splitter PBS again, then passes through the polarization beam splitter PBS, is emitted to the projection lens side (PO), and gray corresponding to the applied voltage for each pixel electrode. ~ Displayed in white.

The above-mentioned liquid crystal display mode is a normally black mode in which black is displayed with no voltage applied, and since it does not receive the birefringence action of the liquid crystal during black display, there is no wavelength dependence in black display and black display is achieved. Since the corresponding signal voltage level is also small, there is an advantage that display characteristics with high contrast can be obtained.
In addition, as an example of a display mode using the same field effect birefringence mode, a liquid crystal material having positive dielectric anisotropy is initially aligned with two substrates substantially parallel to each other and twisted on each other. In addition, it is possible to use a reflective TN mode in which normally white display is performed by arranging liquid crystal molecules in the electric field direction when a voltage is applied.

  Incidentally, in an actual liquid crystal display device, a plan view of the whole is as shown in FIG. 15 (see Patent Document 3). 15 is a plan view showing the liquid crystal display device, and FIG. 16 is an enlarged sectional view of the device shown in FIG. As shown in FIGS. 15 and 16, the first substrate 11 which is an active matrix substrate includes a pixel region 501 in which display pixels Px including a pixel electrode 500 and a switching circuit are arranged in a matrix, and a semiconductor circuit such as a shift register circuit. A peripheral circuit region 504 in which drive circuit units such as a horizontal scan drive circuit 2 and a vertical scan drive circuit 4 for supplying a drive signal (electric signal) to the display pixel Px are arranged, and a seal region 505 on the outer periphery of the peripheral circuit region 504. Consists of. The first substrate 11 is manufactured, for example, by applying a general semiconductor circuit process to a single crystal silicon substrate.

  On the other hand, the second substrate 12 is a counter substrate, and has a configuration in which a transparent counter electrode 13 such as ITO (iridium tin oxide) having optical transparency is laminated on a transparent glass substrate. An alignment film that imparts a predetermined alignment to the liquid crystal is formed on the surface of each of the first substrate 11 and the second substrate 12. The sealant 506 containing spacer particles 511 applied on the seal region 505 of the first substrate 11 is adhered so as to maintain a predetermined gap with the second substrate 12, and two substrates are injected from the injection port 507. A liquid crystal LC is injected between 11 and 12. The injection port 507 is sealed with a sealing material after liquid crystal is injected. Reference numeral 508 denotes an electrode pad group that constitutes a signal supply terminal, and a drive signal necessary for the operation of the active matrix substrate is supplied from an external electric circuit to perform a display operation.

  In manufacturing the liquid crystal display device, when the surface of the pixel electrode 500 is polished, a difference in surface height between the peripheral circuit region 504 and the seal region 505 may occur, and the uniformity of the liquid crystal portion gap may deteriorate. In order to prevent this, dummy electrodes 509 and 510 that are subjected to chemical mechanical polishing similar to the pixel electrode 500 are arranged on the surfaces of the peripheral circuit region 504 and the seal region 505, thereby providing highly uniform display characteristics. Can be realized. In addition, in controlling the liquid crystal gap, a reduction in display quality is taken into consideration, and no seal adhesive is disposed in the pixel region 501, and the liquid crystal gap is sealed with the seal adhesive 506 containing spacer particles 511 applied to the seal region 505. Secure.

  In the reflection type liquid crystal display device, the light reflected by the pixel electrode 500 is used for display. Therefore, the pixel electrode is required to have a high degree of surface property comparable to an optical mirror. In Patent Document 3, the surface of the pixel electrode 500 is polished by chemical mechanical polishing (CMP method: Chemical-Mechanical Polish) to achieve high reflectance characteristics and uniform surface characteristics. On the other hand, since it is technically difficult to uniformly polish the surface of the pixel electrode arranged in a large area by the CMP method, a ground layer that has been planarized in advance by applying CMP to the insulating layer that is the ground of the pixel electrode It is also possible to use a method of forming a pixel electrode on the top of the substrate.

  When a planarization process by the CMP method is applied to the underlying layer of the pixel electrode, a step corresponding to the electrode thickness is generated between each electrode of the pixel electrode. In some cases, the display contrast is lowered and the display uniformity is deteriorated. This problem can be solved by applying a process for flattening between the pixel electrodes.

17 and 18 show an outline of the inter-pixel planarization process. In FIG. 17, the surface insulating layer 120 is polished and planarized by a CMP method in a pre-process for forming the pixel electrode 500 on the first substrate 11. Next, after a contact hole 514 is formed, a metal electrode layer is stacked, and patterning by etching is performed to form the pixel electrode 500. Further, an etch back method is applied in which an insulating layer 515 such as SiO ₂ is uniformly deposited on the surface of the pixel electrode 500 and then etched until the surface of the pixel electrode 500 is exposed. As a result, as shown in FIG. 18, a structure in which the pixel electrodes are filled with the planarizing film 130 can be realized.

  When the inter-pixel planarization process shown in FIGS. 17 and 18 is applied and there is a gap in the electrode structure on the surface between the pixel region 501, the peripheral circuit region 504, and the seal region 505, the planarization layer is formed in the etch back process. As a result of the difference in etching rate, uniform planarization may be difficult. Therefore, as disclosed in Patent Document 3, dummy electrodes 509 and 510 obtained by patterning the same metal layer as the pixel electrode 500 are formed on the peripheral circuit region 504 and the seal region 505, so that the pixel region 501 and the peripheral circuit are formed. It is desirable to maintain a uniform structure as much as possible over the region 504 and the seal region 505.

JP 2003-344824 A JP-A-01-170935 JP 2000-194008 A

  Incidentally, in the conventional reflective liquid crystal display device as described above, the structure in which the dummy electrodes 509 and 510 having the same shape as the pixel electrode 500 are formed on the respective surfaces of the peripheral circuit region 504 and the seal region 505 has uniform display characteristics. It is effective in realizing.

  However, when this structure and the structure in which the liquid crystal gap is controlled by the particle diameter of the spacer particles 511 mixed in the seal adhesive 506 are used in combination, the pressure applied to the first substrate 11 by the spacer particles 511 is applied to the seal region 505. In addition, the sealing adhesive 506 containing a part of the spacer particles 511 also enters the peripheral circuit region 504 side. In this case, as described above, in the structure in which the dummy electrode 509 is provided on the upper surface of the peripheral circuit region 504, the spacer particles 511 crush the dummy electrode 509 as shown in the enlarged view of FIG. A short defect may occur between 530b and the like, and as a result, the manufacturing yield of the liquid crystal display device is significantly reduced.

  As a method of avoiding this short-circuit defect, the size or width of the seal region 505 of the first substrate 11 which is an active matrix substrate is designed to be large in advance so that the seal adhesive 506 does not enter the peripheral circuit region 504 side. A structure that does not overlap is also conceivable. However, when the dimension of the seal region 505 is increased in this way, the first substrate 11 itself, which is an active matrix substrate, becomes larger (larger area), and the number of substrates that can be taken per unit area of the wafer is reduced. There was a problem that the cost of the apparatus was increased.

  The present invention has been devised to pay attention to the above problems and to effectively solve them. The object of the present invention is to suppress the occurrence of short-circuit defects in the peripheral circuit region even when the seal adhesive containing spacer particles enters the peripheral circuit region where the dummy electrode is provided and the spacer particles crush the dummy electrode. An object of the present invention is to provide a liquid crystal display device capable of achieving the above.

  According to the first aspect of the present invention, a display pixel including a pixel electrode and a switching circuit connected to the pixel electrode is provided in a pixel area arranged in a matrix, and provided outside the pixel area, and an electric signal is transmitted to the switching circuit. A first substrate having a peripheral circuit region in which a driving circuit unit for supplying a liquid crystal is disposed, a seal region provided outside the peripheral circuit region and applying a seal adhesive containing spacer particles, and the pixel electrodes Joining the light-transmissive second substrate on which the opposed electrode is formed in a state where the pixel electrodes and the opposed electrode are arranged to face each other and the seal adhesive penetrates into the peripheral circuit region. In the liquid crystal display device in which liquid crystal is sealed between the first and second substrates, a dummy electrode having the same shape as the pixel electrode is formed on the surface of the peripheral circuit region and the seal region. And the dummy electrode at a position corresponding to the wiring connected to the drive circuit portion formed in the peripheral circuit region is divided so as not to straddle between two wirings having different potentials. This is a liquid display device.

  As described above, the dummy electrode positioned above the wiring connected to the drive circuit portion formed in the peripheral circuit region does not cross between two wirings having different electrical meanings, that is, having different potentials. Therefore, even if the seal adhesive containing spacer particles enters the peripheral circuit area where the dummy electrode is provided and the spacer particles crush the dummy electrode, a short defect occurs in the peripheral circuit area. Can be suppressed. Accordingly, a liquid crystal display device having a very small size and uniform and high quality display characteristics can be produced with a high yield.

  In this case, for example, as described in claim 2, the wiring is formed using a wiring layer immediately below the dummy electrode, and is formed so as to cover a region having photosensitivity of the drive circuit unit. Yes.

  According to the liquid crystal display device of the present invention, the dummy electrode located above the wiring connected to the drive circuit unit formed in the peripheral circuit region is straddled between two wirings having different electrical meanings. Since the seal adhesive containing spacer particles penetrates into the peripheral circuit area where the dummy electrodes are provided and the spacer particles crush the dummy electrodes, short circuit defects in the peripheral circuit area are formed. Occurrence can be suppressed. Accordingly, a liquid crystal display device having a very small size and uniform and high quality display characteristics can be produced with a high yield.

Hereinafter, an embodiment of a liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings.
1 is a plan view showing a first embodiment of a liquid crystal display device according to the present invention, FIG. 2 is an enlarged schematic cross-sectional view showing a peripheral portion of the liquid crystal display device shown in FIG. 1, and FIG. 3 shows dummy electrodes in the peripheral circuit region. It is explanatory drawing for demonstrating the condition when it is crushed. The same components as those of the conventional liquid crystal display device are denoted by the same reference numerals.

  As shown in FIGS. 1 and 2, the liquid crystal display device LCD includes a first substrate 11 made of, for example, a single crystal silicon substrate as an active matrix substrate. A pixel region 501 is provided on the center side of the first substrate 11, a dummy pixel region 517 is provided on the outer periphery thereof, a peripheral circuit region 504 is provided on the outer periphery thereof, and further on the outer periphery thereof. Is provided with a sealing region 505. An electrode pad group 508 that relays various signals to and from the outside is arranged on one side of the first substrate 11.

  In the pixel region 501, display pixels Px each including a reflective rectangular pixel electrode 500 and a switching circuit including a switching transistor and a signal storage capacitor are arranged in a matrix. Further, in the peripheral circuit region 504 around the pixel region 501, the horizontal scanning drive circuit 2 and the vertical scanning drive circuit 4 for supplying a drive signal to each display pixel Px are arranged. As described above, the dummy pixel region 517 is disposed between the pixel region 501 and the peripheral circuit region 504. In the dummy pixel region 517, a base semiconductor structure (semiconductor laminated structure) equivalent to the pixel region 501 is formed. As a result, the difference in ground wiring density between the pixel region 501 and the peripheral circuit region 504 is absorbed in the planarization step, and the planarization uniformity of the pixel region 501 adjacent to the peripheral circuit region 504 is improved.

  The structure described with reference to FIGS. 10 to 12 is configured in exactly the same manner in this embodiment, and the description thereof is omitted. As shown in FIG. 2, the peripheral circuit region 504 is provided with a horizontal scanning driving circuit 2 and a vertical scanning driving circuit 4 as a driving circuit unit, and various wirings connected to these circuits. It is done. Here, two wirings having electrically different meanings, that is, having different potentials are represented as wirings 530a and 530b as representatives. The wirings 530a and 530b correspond to ground wirings for supplying a reference potential such as a power supply line and a ground line for the drive circuits 2 and 4, for example. These wirings 530 a and 530 b are appropriately arranged along the circumferential direction of the peripheral circuit region 504.

The wirings 530a and 530b cover the photosensitive region of the semiconductor element, which is a component of the driving circuits 2 and 4 located in the lower layer, to prevent malfunction.
A common trimming electrode 518 is formed in the dummy pixel region 517 and a part (inner peripheral side) of the peripheral circuit region 504 on the dummy pixel region 517 side. The trimming electrode 518 is wide and is formed along the outer peripheral side of the pixel region 501. The function of the trimming electrode 518 is to control the liquid crystal to a black display state in a frame shape at the periphery of the pixel region 501, and the voltage difference between the counter electrode 13 of the second substrate 12 facing the trimming electrode 518 is a liquid crystal. By setting the potential to a voltage corresponding to the black display voltage, the periphery of the pixel region 501 can be trimmed to black.

  The trimming electrode 518 also has a function of shielding a photosensitive region such as a transistor structure in a driving circuit portion located in the lower layer from light, and prevents malfunctions and characteristic fluctuations during light irradiation. The trimming electrode 518 is not divided into patterns like the pixel electrode 500 and needs to be supplied with a predetermined potential, but the seal adhesive 506 is disposed on the outer peripheral side of the panel from the trimming electrode 518. In the trimming electrode 518, the short-circuit defect of the drive circuit portion due to the spacer particles 511 in the seal adhesive 506 does not occur.

  The same material and the same dimensions as the pixel electrode 500 formed in the pixel region 501 are formed on the surface of the region other than the region where the trimming electrode 518 is formed in the peripheral circuit region 504 and the surface of the seal region 505. In addition, dummy electrodes 519 having the same shape are formed. Therefore, the trimming electrode 518 and the dummy electrode 519 exist on the same horizontal level as the pixel electrode 500 formed in the pixel region 501.

  In the dummy electrode 519 above the wiring provided in the peripheral circuit region 504, the dummy electrode is divided into two minute dummy electrodes 519a and 519b so as not to cross between the wirings 530a and 530b. Has been. In other words, when the dummy electrode is positioned on the gap 532 between the two wirings having different electrical meanings as described above, for example, the wirings 530a and 530b, the dummy electrode is, for example, 2 The two dummy electrodes 519a and 519b are divided and arranged so that the dummy electrode does not straddle between the two wirings 530a and 530b. Such a state is realized in all areas of the peripheral circuit area 504.

  Here, an example of the dimensions of each part will be described. Each of the pixel electrode 500, the trimming electrode 518, and the dummy electrodes 519 (519a and 519b) has a thickness of about 0.5 to 0.7 μm. The thickness between the layers is about 0.5 to 0.7 μm, and the average diameter of the spacer particles 511 in the seal adhesive 506 is about 3.2 μm.

  In such a configuration, in order to seal the liquid crystal LC, a seal adhesive 506 mixed with spacer particles 511 is applied to the seal region 505 of the first substrate 11, and the first substrate 11 is applied. Then, the light transmissive second substrate 12 on which the counter electrode 13 is formed is overlapped and bonded to seal the liquid crystal LC. Here, since the width dimension of the seal region 505 is set as narrow as possible in response to a request for downsizing of the apparatus size, the applied seal adhesive 506 penetrates partway into the peripheral circuit region 504 in the inner region. It is inevitable.

  When joining with the seal adhesive 506, a constant pressing force is applied to this portion from the outside. At this time, the spacer particles 511 made of a hard material crush the dummy electrode 519 located in the lower layer. Will occur. In particular, in the peripheral circuit region 504, the uppermost metal wiring layer has a higher probability of being short-circuited by receiving pressure directly from the spacer particle 511 side. In this case, as shown in FIG. 19, which is a conventional device, when the crushed dummy electrode 511 is positioned so as to straddle between two wirings 530a and 530b having different electrical meanings, 530a and 530b were short-circuited through the crushed dummy electrode 511.

  On the other hand, in the case of the present invention, as shown in FIG. 3, the dummy electrode 519 does not straddle the gap 532 between the two wirings 530a and 530b having different electrical meanings. Since it is divided into two minute dummy electrodes 519a and 519b, even if the divided dummy electrodes 519a and 519b are crushed and become conductive with the lower wirings 530a and 530b, both wirings 530a and 519b 530b never shorts. In this way, it is possible to prevent a short defect from occurring. The peripheral circuit region 504 has a large number of wirings having electrically different meanings, and the above-described configuration of dividing into two dummy electrodes 519a and 519b is adopted in all the wirings having electrically different meanings. It is desirable to do.

  As described above, the dummy electrode 519 located above the wiring connected to the drive circuit portions 502 and 503 formed in the peripheral circuit region 504 is straddled between the two wirings 530a and 530b having different electrical meanings. Since the structure is divided so as not to be loosened, the peripheral circuit region 504 is not affected even if the seal adhesive containing spacer particles enters the peripheral circuit region 504 provided with the dummy electrode 519 and the spacer particles crush the dummy electrode. It is possible to suppress the occurrence of short-circuit defects. Accordingly, a liquid crystal display device having a very small size and uniform and high quality display characteristics can be produced with a high yield.

  Here, the power lines and the ground lines have been described as examples of the wirings 519a and 519b having electrically different meanings. However, the present invention is not limited to this, and the signal electrodes D, the selection signals G, and the like are not straddled. Of course, the dummy electrodes may be divided into two, and this point is the same in other embodiments described later.

<Second embodiment>
Next, a second embodiment of the liquid crystal display device of the present invention will be described. 4 is a plan view showing an example of the second embodiment of the liquid crystal display device according to the present invention, FIG. 5 is an enlarged schematic cross-sectional view showing a peripheral portion of the liquid crystal display device shown in FIG. 1, and FIG. 6 is a plan view showing trimming electrodes. FIG. The same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.

  In the first embodiment, the trimming electrode 518 is formed as a larger electrode layer wider than the pixel electrode 500 and the dummy electrode 519. However, the present invention is not limited to this, and the trimming electrode 518 is not limited to the pixel electrode 500 or the dummy electrode. A rectangular pattern 523 having the same size and shape as 519 and having regularity is formed, and each rectangular pattern 523 is bridge-connected by a fine wiring 526 as shown in FIGS. 6A and 6B. You may do it.

  Thus, the trimming electrodes 518 are formed by electrically connecting the rectangular patterns 523 with the fine wirings 526 to form a trimming electrode 518. Therefore, the voltage difference between the trimming electrode 518 and the counter electrode 13 is reduced. By commonly applying a potential that becomes a voltage corresponding to the black display voltage of the liquid crystal LC, the periphery of the pixel region 501 can be trimmed to a uniform black state as in the first embodiment. Further, since the seal adhesive 506 is formed on the outer peripheral side of the panel from the trimming electrode 518, a short circuit defect of the drive circuit portion due to the spacer particles 511 in the seal adhesive 506 does not occur in the trimming electrode 518. .

  In the first embodiment, the wide trimming electrode 518 having no pattern division structure is formed in a part of the dummy pixel region 517 and the peripheral circuit region 504 around the pixel region 501, but this second embodiment. The trimming electrode 518 has a regularity equivalent to that of the pixel electrode 500 and is formed of a plurality of electrically connected rectangular patterns 523 so that a common potential can be supplied. As a result, the pixel electrode 500, the trimming electrode 518, and the dummy electrode 519 are formed with equal regularity over the entire surface of the first substrate 11 that is the active matrix substrate of the liquid crystal display device, and are flat. Further uniformity can be realized in the process, and since the same effect as the first embodiment can be exhibited, for example, short-circuit defects in the peripheral circuit region 514 due to the spacer particles 511 can be reduced. High-quality liquid crystal display device with high yield can be realized.

<Third embodiment>
Next, a third embodiment of the liquid crystal display device of the present invention will be described. FIG. 7 is a block diagram showing a part of the shift register circuit of the drive circuit unit of the third embodiment of the liquid crystal display device according to the present invention, and FIG. 8 is a plan view showing a part of the shift register circuit shown in FIG. FIG. 9 is a schematic cross-sectional view of a shift register circuit.

  In the liquid crystal display device according to the present invention, as a basic function of the drive circuit unit arranged in the peripheral circuit region 504, a display signal is supplied to each pixel Px arranged in a matrix form in the pixel region 501 through the signal electrode D. In addition, it is necessary to supply a selection scanning signal via the selection electrode G, and a shift register circuit is generally used as a circuit for realizing such a circuit function.

  FIG. 7 shows a circuit configuration example of the dynamic shift register circuit used in the liquid crystal display device of the present invention. In the figure, MP represents a P-type MOS transistor, MN represents an N-type MOS transistor, switch circuits (MP1, MN1), (MP3, MN3), (MP5, MN5)... And CMOS inverter circuits (MP2, MN2). ), (MP4, MN4), (MP6, MN6)... Are alternately cascaded for each basic unit, and the ON / OFF of the switch circuit is controlled by control signals Φ1n, Φ1p and Φ2n, Φ2p, respectively. In such a dynamic shift register circuit, the output terminal side (Node 1, 2 and 3 in the figure) is in a floating state for a certain period during the OFF period of the switch circuit, and the transfer operation is sequentially performed by holding the state as signal charges. Do. Therefore, when light is applied to the semiconductor elements connected to these terminal sides (Nodes 1, 2, and 3), signal charge leaks, voltage is insufficiently held in the floating period, and the drive circuit malfunctions. Cause.

  As shown in the first and second embodiments of the present invention, similarly to the pixel electrode 500, the dummy electrode 519 and the trimming electrode 518 (in the case of the second embodiment) having an opening (gap) are patterned by patterning. In the structure formed in the upper layer of 504, it is necessary to devise a method for shielding a photosensitive region from light leaking from the opening so as not to cause a malfunction in a dynamic circuit portion such as a shift register.

  Here, FIG. 8 shows a layout example of the dynamic shift register constituting the drive circuit unit of the previous embodiment. Moreover, the cross-sectional schematic diagram was shown in FIG. The reference numerals in the drawings in both figures correspond to the circuit configuration diagram in FIG. In this embodiment, the upper portion of the semiconductor region corresponding to the charge holding portion of the dynamic shift register is covered with the wiring patterns L1 and L2 of the wiring metal layer. The wiring patterns L1 and L2 can also be used as, for example, reference power supply wirings for supplying power and ground potential to each transistor, for example, wirings 530a and 530b. As is apparent from the schematic cross-sectional structure diagram of FIG. 9, in this structure, the light leaked from the opening (gap) 541 of the dummy electrode 519 formed in the peripheral circuit region 504 has a power supply and ground potential that are located in the lower layer. Light is not shielded by the wiring patterns L1 and L2, and light does not directly reach the semiconductor region corresponding to the charge holding portion of the dynamic shift register. Therefore, a stable display operation without circuit malfunction can be realized.

  Further, regarding the dummy electrodes 519 on the surface of the peripheral circuit region 504 formed on the power supply and ground potential wiring patterns L1 and L2, the wiring patterns L1 and L2 are adjacent to each other and laid out (arranged) in parallel. The portion is divided into two patterns as shown by two fine dummy electrodes 519a and 519b. According to this configuration, when the seal adhesive 506 is formed on the peripheral circuit region 504, even if the spacer particles of the seal adhesive crush the dummy electrode 519, the dummy electrode 519 is thereby formed between the wiring patterns L1 and L2. Therefore, the wiring patterns L1 and L2 are not short-circuited, and the occurrence of circuit malfunction can be prevented.

As described above, according to the liquid crystal display device of the present invention, by providing the peripheral circuit region 504 and the seal region 505 with the dummy electrode 519 made of the same layer as the pixel electrode 500, the uniformity of the planarization process can be improved. Uniform and high-quality display characteristics with small display unevenness can be obtained. In addition, since the display operation defect hardly occurs even when the seal adhesive is applied to the peripheral circuit region 504, at least a part of the seal adhesive can be formed on the peripheral circuit region 504, and the panel area is effectively used. it can. From the above characteristics, a high-quality and low-cost liquid crystal display device can be realized.
Note that although a reflective liquid crystal display device has been described here as an example, the present invention is not limited to this, and the present invention can of course be applied to a transmissive liquid crystal display device.

1 is a plan view showing a first embodiment of a liquid crystal display device according to the present invention. FIG. 2 is an enlarged schematic cross-sectional view showing a peripheral portion of the liquid crystal display device shown in FIG. 1. It is explanatory drawing for demonstrating the condition when the dummy electrode in a peripheral circuit area | region is crushed. It is a top view which shows an example of 2nd Example of the liquid crystal display device based on this invention. FIG. 2 is an enlarged schematic cross-sectional view showing a peripheral portion of the liquid crystal display device shown in FIG. 1. It is a top view which shows a trimming electrode. It is a block block diagram which shows a part of shift register circuit of the drive circuit part of 3rd Example of the liquid crystal display device based on this invention. FIG. 8 is a plan view illustrating a part of the shift register circuit illustrated in FIG. 7. It is a cross-sectional schematic diagram of a shift register circuit. It is a figure which shows the outline | summary of the drive circuit formed in the drive circuit board | substrate of a liquid crystal display device. It is a top view which shows the typical structural example of the display pixel of a general reflection type liquid crystal display device. It is sectional drawing which shows the typical structural example of the display pixel of a general reflection type liquid crystal display device. It is a figure showing the example of the normally black type | mold liquid crystal which made initial stage alignment substantially perpendicular | vertical to a board | substrate. It is a figure showing the operation example of the normally black type | mold liquid crystal which made initial alignment substantially perpendicular | vertical to a board | substrate. It is a top view which shows the conventional liquid crystal display device. It is an expanded sectional view of the apparatus shown in FIG. It is a figure which shows the outline | summary of the planarization process between pixels. It is a figure which shows the outline | summary of the planarization process between pixels. It is a cross-sectional schematic diagram which shows the state which has short-circuited between the two wirings in which the crushed dummy electrode has an electrically different meaning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Horizontal scanning drive circuit, 4 ... Vertical scanning drive circuit, 11 ... 1st board | substrate, 12 ... 2nd board | substrate, 13 ... Counter electrode, 500 ... Pixel electrode, 501 ... Pixel area | region, 504 ... Peripheral circuit area | region 505 ... Sealing area, 506 ... Sealing adhesive, 511 ... Spacer particles, 517 ... Dummy pixel area, 519 ... Dummy electrodes, 519a and 519b ... Divided dummy electrodes, 530a and 530b ... Wiring, LC ... Liquid crystal, LCD ... Liquid crystal display Device, Px ... display pixel.

Claims (2)

A pixel region in which display pixels including a pixel electrode and a switching circuit connected to the pixel electrode are arranged in a matrix, and a drive circuit unit that is provided outside the pixel region and supplies an electrical signal to the switching circuit are arranged A first substrate having a peripheral circuit region and a seal region provided outside the peripheral circuit region and applying a seal adhesive containing spacer particles;
A light transmissive second substrate on which a counter electrode facing each pixel electrode is formed;
A liquid crystal display in which each pixel electrode and the counter electrode are arranged to face each other and bonded together in a state where the seal adhesive penetrates into the peripheral circuit region, and liquid crystal is sealed between the first and second substrates. In the device
A dummy electrode having the same shape as that of the pixel electrode is formed on the surfaces of the peripheral circuit region and the seal region, and at a position corresponding to a wiring connected to the drive circuit unit formed in the peripheral circuit region. A liquid display device, wherein the dummy electrode is divided so as not to straddle between two wirings having different potentials. 2. The liquid crystal display according to claim 1, wherein the wiring is formed by using a wiring layer immediately below the dummy electrode, and is formed so as to cover a region having photosensitivity of the drive circuit unit. apparatus.

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