Liquid crystal display device

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.

CROSS-REFERENCE TO RELATED APPLICATION

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

1. Field of the Invention

2. Description of the Related Art

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.

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.

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.

In the liquid crystal display device having the frame area thus narrowed, an oriented film that defines the orientation of the liquid crystal composition may be 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

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.

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.

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.

Also, in the liquid crystal display device according to the present invention, the light transmission area may be surrounded by a gate signal line of the main transistor in at least three ways, when viewed from the display direction.

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.

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.

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.

Also, in the liquid crystal display device according to the present invention, the oriented film may be stacked on the light transmission area.

DETAILED DESCRIPTION OF THE INVENTION

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

FIG. 1schematically illustrates a liquid crystal display device100according to a first embodiment of the present invention. As illustrated in the figure, the liquid crystal display device100includes a liquid crystal panel200fixed to be sandwiched between an upper frame101and a lower frame102.

FIG. 2illustrates a front view of the liquid crystal panel200. As illustrated in the figure, the liquid crystal panel200includes a thin film transistor substrate201having pixel circuits each using a thin film transistor formed in a display area203, and a driver circuit204using thin film transistors formed around the display area203, a color filter substrate202having 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 substrate201, a liquid crystal composition sealed between the thin film transistor substrate201and the color filter substrate202, and a seal material205for sealing the liquid crystal composition between the thin film transistor substrate201and the color filter substrate202.

FIG. 3is an enlarged diagram illustrating an appearance of wiring in an area A of the driver circuit204inFIG. 2. InFIG. 3, there are shown a scanning signal line305that is connected to gates of pixel transistors in the display area, a plurality of circuit drive signal lines302to which a plurality of different clock signals are each supplied, a main transistor310for supplying a clock signal of one circuit drive signal line302to the scanning signal line305at a given timing, a capacitor303, and a capacitor304. As illustrated in the figure, the main transistor310includes pectinate channel areas311and312having pectinate source and drain electrodes engaged with each other. Between the pectinate channel areas311and312are formed a light transmission area313in 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.

The circuit and wirings illustrated inFIG. 3are exemplary, and a circuit used for the driver circuit204may be another circuit that supplies a pulse signal to the scanning signal line at a given timing. In this example, the light transmission area313is surrounded by a gate signal line formed of a first conductive film321in four ways, and also surrounded by a source signal line and a drain signal line formed of a second conductive film323in three ways.

FIG. 4illustrates a circuit diagram of the main transistor310. As illustrated in the circuit diagram, the main transistor310is configured so that a first sub-transistor331formed by the pectinate channel area311and a second sub-transistor332formed by the pectinate channel area312are connected in parallel to each other. A gate, a drain, and a source of the first sub-transistor331, and a gate, a drain, and a source of the second sub-transistor332are connected to one node315, one pulse signal line316, and one fixed signal line317, respectively.

FIG. 5is a schematically cross-sectional view taken along a line V-V inFIG. 3.FIG. 5illustrates a cross-section of the main transistor310and the capacitor303with the inclusion of the first conductive film321which is an opaque metal film formed as a part of the thin film transistor substrate201, a first insulating film322, a semiconductor film326, the second conductive film323which is an opaque metal film, a second insulating film324, an oriented film325formed so as to be poured from the display area203side, and the seal material205formed for sealing the liquid crystal composition between the seal material205and the color filter substrate202. The liquid crystal composition and the film on the color filter substrate202are omitted from the drawing.

As schematically illustrated in the figure, the first conductive film321, the first insulating film322, the semiconductor film326, the second conductive film323, and the second insulating film324are formed in the stated order. Thereafter, the oriented film325formed so as to be poured from the display area203side is so stemmed as to be impounded in a recess C of the light transmission area313, and the oriented film325is not arranged in an area D. With this configuration, a high sealing property area328is formed in which the second insulating film324and the seal material205come into direct contact with each other through no oriented film325. As a result, the adhesiveness and the tightness of the seal material205can 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.

Also, in an ultraviolet irradiation process for curing the seal material205, because ultraviolet rays transmit from the light transmission area313, the seal material205can be sufficiently cured, and moisture can be prevented from penetrating inside of the liquid crystal panel caused by uncuring.

FIG. 6schematically illustrates a main transistor410which is a first modified example of the main transistor310of the first embodiment. As illustrated in the figure, in the main transistor410, the light transmission area313is formed between pectinate channel areas411and412as in the main transistor310. However, the main transistor410is different from the main transistor310in that a direction of extending the light transmission area313is perpendicular to a direction of extending the pectinate source and drain. Even in this configuration, the main transistor410is configured so that a first sub-transistor formed by the pectinate channel area411and a second sub-transistor formed by the pectinate channel area412are connected in parallel to each other. Also, the light transmission area313is surrounded by a gate signal line formed of the first conductive film321in four ways, and surrounded by a source signal line and a drain signal line formed of the second conductive film323in three ways.

FIG. 7schematically illustrates a main transistor420which is a second modified example of the main transistor310of the first embodiment. As illustrated in the figure, the main transistor420is formed into a crank shape as a whole to form pectinate channel areas421and422, and the light transmission area313is formed between the pectinate channel areas421and422. Thus, the main transistor420is 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 inFIG. 7is 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 transistor420is configured so that the first sub-transistor formed by the pectinate channel area421and the second sub-transistor formed by the pectinate channel area422are connected in parallel to each other. Also, the light transmission area313is surrounded by the gate signal line formed of the first conductive film321in four ways, and also surrounded by the source signal line and the drain signal line formed of the second conductive film323in the three directions.

FIG. 8schematically illustrates a main transistor430which is a third modified example of the main transistor310of the first embodiment. As illustrated in the figure, as in the second modified example, the main transistor430is formed into a crank shape as a whole to form pectinate channel areas431and432, and the light transmission area313is formed between the pectinate channel areas431and432. In this example, the light transmission area313is 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 area313coupled to a boundary between the main transistor and the adjacent main transistor. With the above configuration, the oriented film325(refer toFIG. 5) poured into the boundary between the respective main transistors as indicated by an arrow inFIG. 8can arrive at the light transmission area313without a need to exceed a barrier of height, and the oriented film325is liable to be accumulated in the light transmission area313. Even in this configuration, the main transistor430is configured so that the first sub-transistor formed by the pectinate channel area431and the second sub-transistor formed by the pectinate channel area432are connected in parallel to each other. Also, the light transmission area313is surrounded by the gate signal line formed of the first conductive film321in the three ways, and also surrounded by the source signal line and the drain signal line formed of the second conductive film323in the three ways.

FIG. 9schematically illustrates a main transistor440which is a fourth modified example of the main transistor310of the first embodiment. As illustrated in the figure, as in the third modified example, the main transistor440is formed into a crank shape as a whole to form pectinate channel areas441and442, and the light transmission area313coupled to the boundary between the main transistor and the adjacent main transistor is formed. Further, the main transistor440is different from the main transistor310in that the first conductive film321and the semiconductor film326are separated by the pectinate channel areas441and442. With this configuration, the oriented film325(refer toFIG. 5) is poured into the light transmission area313from two ways as indicated by an arrow inFIG. 9so that the oriented film325is more liable to be accumulated in the light transmission area313. Even in this configuration, the main transistor440is configured so that the first sub-transistor formed by the pectinate channel area441and the second sub-transistor formed by the pectinate channel area442are connected in parallel to each other. Also, the light transmission area313is surrounded by the source signal line and the drain signal line formed of the second conductive film323in the three ways.

Even in the configurations illustrated in the above-mentioned first to fourth modified examples, as with the main transistor310in the first embodiment, the oriented film is so stemmed as to be impounded in the light transmission area313, and a high sealing property area328in 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.

Also, in the ultraviolet irradiation process for curing the seal material, because ultraviolet rays transmit from the light transmission area313, 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

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 inFIGS. 1 and 2, and therefore a repetitive description will be omitted.

FIG. 10is an enlarged diagram illustrating an appearance of wiring in an area A of the driver circuit204inFIG. 2. InFIG. 10, as inFIG. 3of the first embodiment, there are shown a scanning signal line505that is connected to gates of pixel transistors in the display area, a plurality of circuit drive signal lines502to which a plurality of different clock signals are each supplied, a main transistor510for supplying a clock signal of one circuit drive signal line502to the scanning signal line505at a given timing, a capacitor503, and a capacitor504. As illustrated in the figure, inside of each of the capacitor503and the capacitor504a non-transparent conductive film is not formed, but a light transmission area513which 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 area513is surrounded by electrodes of the capacitor503or504in the four ways, but may be surrounded in the three ways, and opened in one way.

FIG. 11is a circuit diagram of the capacitor503divided by the light transmission area513. As illustrated in the circuit diagram, the capacitor503is structured by a first sub-capacitor511and a second sub-capacitor512which are divided by the light transmission area513and connected in parallel to each other. Both ends of the first sub-capacitor511and the second sub-capacitor512are connected to one scanning signal line516and one fixed signal line517, respectively.

FIG. 12is a schematically cross-sectional view taken along a line XII-XII inFIG. 10.FIG. 12illustrates a cross-section of the sub-capacitor512, with the inclusion of the first conductive film321which is an opaque metal film formed as a part of the thin film transistor substrate201, the first insulating film322, the second conductive film323that is an opaque metal film, the second insulating film324, the oriented film325formed so as to be poured from the display area203side, and the seal material205formed for sealing the liquid crystal composition between the thin film transistor substrate201and the color filter substrate202. The liquid crystal composition and the film on the color filter substrate202are omitted from the drawing.

As illustrated in the figure, the first conductive film321, the first insulating film322, the second conductive film323, and the second insulating film324are formed in the stated order. Thereafter, the oriented film325formed so as to be poured from the display area203side is so stemmed as to be impounded in a recess E of the light transmission area513, and the oriented film325is not arranged in an area F. With this configuration, a high sealing property area528is formed in which the second insulating film324and the seal material205come into direct contact with each other through no oriented film325. As a result, the adhesiveness and the tightness of the seal material205can 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.

Also, in an ultraviolet irradiation process for curing the seal material205, because ultraviolet rays transmit from the light transmission area313, the seal material205can be sufficiently cured, and moisture can be prevented from penetrating inside of the liquid crystal panel caused by uncuring.

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.