Abstract:
A liquid crystal display device includes a thin film transistor substrate, a counter substrate that faces the thin film transistor substrate, a liquid crystal composition that is arranged between the thin film transistor substrate and the counter substrate, an oriented film that arranges orientation of the liquid crystal composition contacting with the thin film transistor substrate, a seal material that seals the liquid crystal composition between the two substrates, and a driver circuit. The driver circuit has a light transmission area that is formed inside of the driver circuit, and is higher in light transmittance than an area in which a non-transparent conductive film forming the driver circuit is formed, and a high sealing property area in which the seal material and an insulating film come into direct contact with each other between the light transmission area and an outer edge of the thin film transistor substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese application JP2011-254094 filed on Nov. 21, 2011, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a liquid crystal display device. 
         [0004]    2. Description of the Related Art 
         [0005]    As an information communication terminal such as a computer and a display device such as a television, liquid crystal display devices have been widely used. The liquid crystal display device changes an orientation of a liquid crystal composition confined between two glass substrates according to a change in electric field, and controls the degree of transmission of light that passes through the two glass substrates and the liquid crystal composition to display an image. 
         [0006]    In the liquid crystal display device, there is a need to arrange a driver circuit for applying a voltage corresponding to a given tone value to respective pixels on a screen on the glass substrate or a circuit board connected to the glass substrate. There has been known the driver circuit that is incorporated into an IC (integrated circuit) chip, and placed on the glass substrate. In recent years, it is desirable to narrow an area outside a display area on the glass substrate (hereinafter referred to as “frame area”). Therefore, there is a case in which a thin film transistor is formed on the frame area without mounting the IC chip thereon, and the driver circuit is arranged directly on the glass substrate without using the IC chip. 
         [0007]    JP 2006-080472 A discloses a structure in which a parasitic capacity is reduced in an amorphous silicon thin film transistor arranged in the frame area. 
         [0008]    In the liquid crystal display device having the frame area thus narrowed, an oriented film that defines the orientation of the liquid crystal composition maybe formed on the driver circuit, and a seal with which a portion between the glass substrates is sealed may be formed on the oriented film. In this case, when the adhesiveness of the seal formed on the oriented film is not sufficient, or the seal is not sufficiently cured, there is a risk that moisture penetrates inside of a panel to adversely affect the characteristic of the liquid crystal composition. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention has been made in view of the above-mentioned circumstances, and therefore an object of the present invention is to provide a display device that can seal the liquid crystal composition with high sealing property while realizing the narrowed frame area. 
         [0010]    According to the present invention, there is provided a liquid crystal display device, including a thin film transistor substrate on which a thin film transistor is formed; a counter substrate that faces a surface of the thin film transistor substrate on which the thin film transistor is formed; a liquid crystal composition that is arranged between the thin film transistor substrate and the counter substrate; an oriented film that arranges orientation of the liquid crystal composition contacting with the thin film transistor substrate; a seal material that sticks the thin film transistor substrate and the counter substrate together, and seals the liquid crystal composition; and a driver circuit that is formed outside of a display area of the thin film transistor substrate with the user of the thin film transistor, and outputs a scanning signal to scanning signal lines in the display area, in which the driver circuit has a light transmission area that is formed inside of the driver circuit, and is higher in light transmittance than an area in which a non-transparent conductive film forming the driver circuit is formed, and a high sealing property area in which the seal material and an insulating film come into direct contact with each other between the light transmission area and an outer edge of the thin film transistor substrate, when viewed from a display direction. 
         [0011]    Also, in the liquid crystal display device according to the present invention, in the driver circuit, a main transistor having a source or a drain connected directly or indirectly to the scanning signal line may have a plurality of pectinate channel areas in which a pectinate drain signal line and a pectinate source signal line are alternating with each other, the transistors formed by the plurality of pectinate channel areas may form circuits connected in parallel to each other, and the light transmission area may be arranged between the plurality of pectinate channel areas when viewed from the display direction. 
         [0012]    Also, in the liquid crystal display device according to the present invention, the light transmission area may be surrounded by agate signal line of the main transistor in at least three ways, when viewed from the display direction. 
         [0013]    Also, in the liquid crystal display device according to the present invention, the light transmission area may be surrounded by at least one of a source signal line and a drain signal line of the main transistor in at least three ways, when viewed from the display direction. 
         [0014]    Also, in the liquid crystal display device according to the present invention, the plurality of pectinate channel areas may be formed by forming the main transistor into a crank shape as a whole. 
         [0015]    Also, in the liquid crystal display device according to the present invention, the light transmission area may be surrounded by an electrode forming a capacitor in the driver circuit in at least three ways, when viewed from the display direction. 
         [0016]    Also, in the liquid crystal display device according to the present invention, the oriented film may be stacked on the light transmission area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic diagram illustrating a liquid crystal display device according to a first embodiment of the present invention; 
           [0018]      FIG. 2  is a front view illustrating a liquid crystal panel in  FIG. 1 ; 
           [0019]      FIG. 3  is an enlarged diagram illustrating an appearance of wiring in an area A of a driver circuit in  FIG. 2 ; 
           [0020]      FIG. 4  is a circuit diagram illustrating a main transistor in  FIG. 3 ; 
           [0021]      FIG. 5  is a schematically cross-sectional view taken along a line V-V in  FIG. 3 ; 
           [0022]      FIG. 6  is a diagram illustrating a main transistor according to a first modified example of the first embodiment; 
           [0023]      FIG. 7  is a diagram illustrating a main transistor according to a second modified example of the first embodiment; 
           [0024]      FIG. 8  is a diagram illustrating a main transistor according to a third modified example of the first embodiment; 
           [0025]      FIG. 9  is a diagram illustrating a main transistor according to a fourth modified example of the first embodiment; 
           [0026]      FIG. 10  is an enlarged diagram illustrating an appearance of wiring in an area A of a driver circuit in  FIG. 2  in the second embodiment; 
           [0027]      FIG. 11  is a circuit diagram of a capacitor in  FIG. 10 ; and 
           [0028]      FIG. 12  is a schematically cross-sectional view taken along a line XII-XII in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    Hereinafter, a description will be given of a first embodiment and a second embodiment of the present invention with reference to the accompanying drawings. In the drawings, the same or equivalent elements are denoted by identical reference numerals or symbols, and repetitive description will be omitted. 
       First Embodiment 
       [0030]      FIG. 1  schematically illustrates a liquid crystal display device  100  according to a first embodiment of the present invention. 
         [0031]    As illustrated in the figure, the liquid crystal display device  100  includes a liquid crystal panel  200  fixed to be sandwiched between an upper frame  101  and a lower frame  102 . 
         [0032]      FIG. 2  illustrates a front view of the liquid crystal panel  200 . As illustrated in the figure, the liquid crystal panel  200  includes a thin film transistor substrate  201  having pixel circuits each using a thin film transistor formed in a display area  203 , and a driver circuit  204  using thin film transistors formed around the display area  203 , a color filter substrate  202  having color filters of respective colors of R (red), G (green), and B (blue) formed for each of pixels, which is a counter substrate facing the thin film transistor substrate  201 , a liquid crystal composition sealed between the thin film transistor substrate  201  and the color filter substrate  202 , and a seal material  205  for sealing the liquid crystal composition between the thin film transistor substrate  201  and the color filter substrate  202 . 
         [0033]      FIG. 3  is an enlarged diagram illustrating an appearance of wiring in an area A of the driver circuit  204  in  FIG. 2 . In  FIG. 3 , there are shown a scanning signal line  305  that is connected to gates of pixel transistors in the display area, a plurality of circuit drive signal lines  302  to which a plurality of different clock signals are each supplied, a main transistor  310  for supplying a clock signal of one circuit drive signal line  302  to the scanning signal line  305  at a given timing, a capacitor  303 , and a capacitor  304 . As illustrated in the figure, the main transistor  310  includes pectinate channel areas  311  and  312  having pectinate source and drain electrodes engaged with each other. Between the pectinate channel areas  311  and  312  are formed a light transmission area  313  in which a non-transparent conductive film is not formed, but a light transmittance is higher than that in an area where the non-transparent conductive film is formed. 
         [0034]    The circuit and wirings illustrated in  FIG. 3  are exemplary, and a circuit used for the driver circuit  204  may be another circuit that supplies a pulse signal to the scanning signal line at a given timing. In this example, the light transmission area  313  is surrounded by a gate signal line formed of a first conductive film  321  in four ways, and also surrounded by a source signal line and a drain signal line formed of a second conductive film  323  in three ways. 
         [0035]      FIG. 4  illustrates a circuit diagram of the main transistor  310 . As illustrated in the circuit diagram, the main transistor  310  is configured so that a first sub-transistor  331  formed by the pectinate channel area  311  and a second sub-transistor  332  formed by the pectinate channel area  312  are connected in parallel to each other. A gate, a drain, and a source of the first sub-transistor  331 , and a gate, a drain, and a source of the second sub-transistor  332  are connected to one node  315 , one pulse signal line  316 , and one fixed signal line  317 , respectively.  FIG. 5  is a schematically cross-sectional view taken along a line V-V in  FIG. 3 .  FIG. 5  illustrates a cross-section of the main transistor  310  and the capacitor  303  with the inclusion of the first conductive film  321  which is an opaque metal film formed as a part of the thin film transistor substrate  201 , a first insulating film  322 , a semiconductor film  326 , the second conductive film  323  which is an opaque metal film, a second insulating film  324 , an oriented film  325  formed so as to be poured from the display area  203  side, and the seal material  205  formed for sealing the liquid crystal composition between the seal material  205  and the color filter substrate  202 . The liquid crystal composition and the film on the color filter substrate  202  are omitted from the drawing. 
         [0036]    As schematically illustrated in the figure, the first conductive film  321 , the first insulating film  322 , the semiconductor film  326 , the second conductive film  323 , and the second insulating film  324  are formed in the stated order. Thereafter, the oriented film  325  formed so as to be poured from the display area  203  side is so stemmed as to be impounded in a recess C of the light transmission area  313 , and the oriented film  325  is not arranged in an area D. With this configuration, a high sealing property area  328  is formed in which the second insulating film  324  and the seal material  205  come into direct contact with each other through no oriented film  325 . As a result, the adhesiveness and the tightness of the seal material  205  can be improved, moisture can be prevented from penetrating inside of a liquid crystal panel, and the characteristics of the liquid crystal composition can be enhanced. 
         [0037]    Also, in an ultraviolet irradiation process for curing the seal material  205 , because ultraviolet rays transmit from the light transmission area  313 , the seal material  205  can be sufficiently cured, and moisture can be prevented from penetrating inside of the liquid crystal panel caused by uncuring. 
         [0038]      FIG. 6  schematically illustrates a main transistor  410  which is a first modified example of the main transistor  310  of the first embodiment. As illustrated in the figure, in the main transistor  410 , the light transmission area  313  is formed between pectinate channel areas  411  and  412  as in the main transistor  310 . However, the main transistor  410  is different from the main transistor  310  in that a direction of extending the light transmission area  313  is perpendicular to a direction of extending the pectinate source and drain. Even in this configuration, the main transistor  410  is configured so that a first sub-transistor formed by the pectinate channel area  411  and a second sub-transistor formed by the pectinate channel area  412  are connected in parallel to each other. Also, the light transmission area  313  is surrounded by a gate signal line formed of the first conductive film  321  in four ways, and surrounded by a source signal line and a drain signal line formed of the second conductive film  323  in three ways. 
         [0039]      FIG. 7  schematically illustrates a main transistor  420  which is a second modified example of the main transistor  310  of the first embodiment. As illustrated in the figure, the main transistor  420  is formed into a crank shape as a whole to form pectinate channel areas  421  and  422 , and the light transmission area  313  is formed between the pectinate channel areas  421  and  422 . Thus, the main transistor  420  is formed into the crank shape as a whole, as a result of which a boundary between the main transistor and the adjacent main transistor is also formed into the crank shape, and a progress of the oriented film poured into the configuration as illustrated in  FIG. 7  is slowed, thereby making it difficult to put the oriented film on an entire surface of the second insulating film. As a result, the second insulating film and the seal material are liable to come into direct contact with each other. Even in this configuration, the main transistor  420  is configured so that the first sub-transistor formed by the pectinate channel area  421  and the second sub-transistor formed by the pectinate channel area  422  are connected in parallel to each other. Also, the light transmission area  313  is surrounded by the gate signal line formed of the first conductive film  321  in four ways, and also surrounded by the source signal line and the drain signal line formed of the second conductive film  323  in the three directions. 
         [0040]      FIG. 8  schematically illustrates a main transistor  430  which is a third modified example of the main transistor  310  of the first embodiment. As illustrated in the figure, as in the second modified example, the main transistor  430  is formed into a crank shape as a whole to form pectinate channel areas  431  and  432 , and the light transmission area  313  is formed between the pectinate channel areas  431  and  432 . In this example, the light transmission area  313  is not arranged between the source line and the drain linen as in the second modified example, but the source line and the drain line approach one side, and the other side at which the source line and the drain line are not present is set as the light transmission area  313  coupled to a boundary between the main transistor and the adjacent main transistor. With the above configuration, the oriented film  325  (refer to  FIG. 5 ) poured into the boundary between the respective main transistors as indicated by an arrow in  FIG. 8  can arrive at the light transmission area  313  without a need to exceed a barrier of height, and the oriented film  325  is liable to be accumulated in the light transmission area  313 . Even in this configuration, the main transistor  430  is configured so that the first sub-transistor formed by the pectinate channel area  431  and the second sub-transistor formed by the pectinate channel area  432  are connected in parallel to each other. Also, the light transmission area  313  is surrounded by the gate signal line formed of the first conductive film  321  in the three ways, and also surrounded by the source signal line and the drain signal line formed of the second conductive film  323  in the three ways. 
         [0041]      FIG. 9  schematically illustrates a main transistor  440  which is a fourth modified example of the main transistor  310  of the first embodiment. As illustrated in the figure, as in the third modified example, the main transistor  440  is formed into a crank shape as a whole to form pectinate channel areas  441  and  442 , and the light transmission area  313  coupled to the boundary between the main transistor and the adjacent main transistor is formed. Further, the main transistor  440  is different from the main transistor  310  in that the first conductive film  321  and the semiconductor film  326  are separated by the pectinate channel areas  441  and  442 . With this configuration, the oriented film  325  (refer to  FIG. 5 ) is poured into the light transmission area  313  from two ways as indicated by an arrow in  FIG. 9  so that the oriented film  325  is more liable to be accumulated in the light transmission area  313 . Even in this configuration, the main transistor  440  is configured so that the first sub-transistor formed by the pectinate channel area  441  and the second sub-transistor formed by the pectinate channel area  442  are connected in parallel to each other. Also, the light transmission area  313  is surrounded by the source signal line and the drain signal line formed of the second conductive film  323  in the three ways. 
         [0042]    Even in the configurations illustrated in the above-mentioned first to fourth modified examples, as with the main transistor  310  in the first embodiment, the oriented film is so stemmed as to be impounded in the light transmission area  313 , and a high sealing property area  328  in which the second insulating film and the seal material come into direct contact with each other through no oriented film is formed. As a result, the adhesiveness and the tightness of the seal material can be improved, moisture can be prevented from penetrating inside of the liquid crystal panel, and the characteristics of the liquid crystal composition can be enhanced. 
         [0043]    Also, in the ultraviolet irradiation process for curing the seal material, because ultraviolet rays transmit from the light transmission area  313 , the seal material can be sufficiently cured, and moisture can be prevented from penetrating inside of the liquid crystal panel caused by uncuring. 
       Second Embodiment 
       [0044]    A second embodiment of the present invention will be described. A configuration of a display device according to the second embodiment is identical with the configuration of the first embodiment illustrated in  FIGS. 1 and 2 , and therefore a repetitive description will be omitted. 
         [0045]      FIG. 10  is an enlarged diagram illustrating an appearance of wiring in an area A of the driver circuit  204  in  FIG. 2 . In  FIG. 10 , as in  FIG. 3  of the first embodiment, there are shown a scanning signal line  505  that is connected to gates of pixel transistors in the display area, a plurality of circuit drive signal lines  502  to which a plurality of different clock signals are each supplied, a main transistor  510  for supplying a clock signal of one circuit drive signal line  502  to the scanning signal line  505  at a given timing, a capacitor  503 , and a capacitor  504 . As illustrated in the figure, inside of each of the capacitor  503  and the capacitor  504  a non-transparent conductive film is not formed, but a light transmission area  513  which is higher in the light transmittance than that an area where the non-transparent conductive film is formed is formed. In this example, the light transmission area  513  is surrounded by electrodes of the capacitor  503  or  504  in the four ways, but may be surrounded in the three ways, and opened in one way. 
         [0046]      FIG. 11  is a circuit diagram of the capacitor  503  divided by the light transmission area  513 . As illustrated in the circuit diagram, the capacitor  503  is structured by a first sub-capacitor  511  and a second sub-capacitor  512  which are divided by the light transmission area  513  and connected in parallel to each other. Both ends of the first sub-capacitor  511  and the second sub-capacitor  512  are connected to one scanning signal line  516  and one fixed signal line  517 , respectively. 
         [0047]      FIG. 12  is a schematically cross-sectional view taken along a line XII-XII in  FIG. 10 .  FIG. 12  illustrates a cross-section of the sub-capacitor  512 , with the inclusion of the first conductive film  321  which is an opaque metal film formed as a part of the thin film transistor substrate  201 , the first insulating film  322 , the second conductive film  323  that is an opaque metal film, the second insulating film  324 , the oriented film  325  formed so as to be poured from the display area  203  side, and the seal material  205  formed for sealing the liquid crystal composition between the thin film transistor substrate  201  and the color filter substrate  202 . The liquid crystal composition and the film on the color filter substrate  202  are omitted from the drawing. 
         [0048]    As illustrated in the figure, the first conductive film  321 , the first insulating film  322 , the second conductive film  323 , and the second insulating film  324  are formed in the stated order. Thereafter, the oriented film  325  formed so as to be poured from the display area  203  side is so stemmed as to be impounded in a recess E of the light transmission area  513 , and the oriented film  325  is not arranged in an area F. With this configuration, a high sealing property area  528  is formed in which the second insulating film  324  and the seal material  205  come into direct contact with each other through no oriented film  325 . As a result, the adhesiveness and the tightness of the seal material  205  can be improved, moisture can be prevented from penetrating inside of a liquid crystal panel, and the characteristics of the liquid crystal composition can be enhanced. 
         [0049]    Also, in an ultraviolet irradiation process for curing the seal material  205 , because ultraviolet rays transmit from the light transmission area  313 , the seal material  205  can be sufficiently cured, and moisture can be prevented from penetrating inside of the liquid crystal panel caused by uncuring. 
         [0050]    The liquid crystal display device according to the above-mentioned embodiments can be applied to any one of an IPS (in-plane switching) system, a VA (vertically aligned) system, and a TN (twisted nematic) system although the system is not particularly designated. 
         [0051]    While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention.