JP2009058982A - Transflective liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent inversion of display between an in-plane switching transmissive display part and a twisted nematic reflective display part in a transflective liquid crystal display. <P>SOLUTION: Two switching elements 23, 25 are provided at each intersection of data lines 31 and gate lines 29 arranged in a matrix. One switching element 23 acts for a transmissive display part 12 and its output terminal is connected to a common electrode 42 for transmissive display through a capacitance TC of the transmissive display part; while the other switching element 25 acts for a reflective display part 14 and its output terminal is connected to a holding capacitance electrode 41 for reflective display through a storage capacitance RC<SB>SC</SB>of the reflective display part 14 and connected to a common electrode 70 for reflective display through a liquid crystal capacitance RC<SB>LC</SB>. The potential of the common electrode 42 for transmissive display and the potential of the common electrode 70 for reflective display are in reversed phases to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a transflective liquid crystal display device, and in particular, drives a liquid crystal molecule by sandwiching a liquid crystal layer between an element substrate and a counter substrate and applying an electric field between a pixel electrode and a common electrode on the element substrate. The present invention relates to a transflective liquid crystal display device including a transmissive display unit that performs liquid crystal molecules driving between a pixel electrode and a reflective display common electrode on a counter substrate.

A liquid crystal display device for portable devices represented by a mobile phone, a PDA (Personal Digital Assistant), a digital still camera, a digital video camera, and the like is required to have high visibility in various environments from outdoor to indoor. In such a background, in recent years, a so-called transflective liquid crystal display device having both a transmissive display portion and a reflective display portion in a sub-pixel has attracted attention.

Conventionally, as a transflective liquid crystal display device, a so-called vertical electric field driving method in which liquid crystal molecules are driven by an electric field between a pixel electrode of an element substrate and a common electrode of a counter substrate has been generally used.
In a transflective liquid crystal display device in which a transmissive display unit and a reflective display unit are provided in a subpixel,
Since the optical path of the reflective display unit is double that of the transmissive display unit, half-wave (λ / 2) light modulation is performed in the transmissive display mode, and quarter-wave (λ / 4) light is used in the reflective display mode. It is necessary to use modulation, for example, by providing different liquid crystal layer thicknesses (cell gaps) in the subpixels.

FFS (Fringe Field), known for its high viewing angle and high contrast
If a transflective liquid crystal display device of a so-called lateral electric field drive system such as switching) or IPS (In Plane Switching) is put into practical use, better visibility than the conventional one can be expected.

In such a background, it has been proposed to use a horizontal electric field driving method for the transmissive display portion and a vertical electric field driving method for the reflective display portion. However, if a conventional configuration for adjusting the cell gap is used, The problem that the transmissive display portion is normally white and the reflective display portion is normally black has been pointed out.

For example, Patent Document 1 discloses various studies on a transflective IPS method in which a horizontal electric field is applied to a liquid crystal layer. Among them, a transmissive display unit has a horizontal electric field drive method, and a reflective display unit has a It is pointed out that when the vertical electric field driving method is used, the transmissive display portion is normally white and the reflective display portion is normally black, and the reflective display portion and the transmissive display portion have different applied voltage dependencies. In order to solve this problem, it is disclosed that a built-in phase plate having a retardation of 1/2 wavelength is formed on the reflective display unit, and the retardation of the liquid crystal layer of the reflective display unit is set to a quarter wavelength. ing.

Similarly, in Patent Document 2, when the horizontal electric field driving method is used for the transmissive display unit and the vertical electric field driving method is used for the reflective display unit, the transmissive display unit is normally white and the reflective display unit is normally black. It points out that it becomes. In order to solve this, it is disclosed that a half-wave plate is disposed between a lower substrate and a polarizing plate installed on the lower substrate side.

A mechanism in which the horizontal electric field drive transmissive display unit is normally white and the vertical electric field drive reflection display unit is normally black will be described in detail later in comparison with the embodiment of the present invention.

JP 2005-338256 A JP 2003-344837 A

As described above, in the transflective liquid crystal display device, when the horizontal electric field driving method is applied to the transmissive display unit, there is a problem that the transmissive display unit is normally white and the vertical electric field driving type reflective display unit is normally black. . In order to adopt the technique shown in Patent Documents 1 and 2 for normal display, that is, for both the transmissive display portion and the reflective display portion to be normally black or normally white, the configuration of the panel is complicated. Become. Another possible solution is to make the video signal supplied from the data line different between the transmissive display part and the reflective display part, but this complicates the signal processing and the device structure of the panel. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a transflective liquid crystal display device that can perform good display without causing display inversion between a transmissive display unit driven by a horizontal electric field and a reflective display unit driven by a vertical electric field. It is.

The transflective liquid crystal display device according to the present invention sandwiches a liquid crystal layer between an element substrate and a counter substrate,
A transflective liquid crystal display device including a reflective display unit and a transmissive display unit, wherein the element substrate is provided at each of intersections of a plurality of data lines, a plurality of gate lines, and the data lines and the gate lines. A transmissive display for driving liquid crystal molecules by applying an electric field between the plurality of arranged switching elements, a plurality of pixel electrodes respectively connected to output ends of the plurality of switching elements, and the pixel electrodes A common electrode for reflection, and the counter substrate has a common electrode for reflective display for driving liquid crystal molecules by applying an electric field between the pixel electrode and the potential of the common electrode for reflective display. The potentials of the transmissive display common electrode are opposite to each other.

In the transflective liquid crystal display device according to the present invention, the potential of the common electrode for reflective display and the common electrode for transmissive display which are common to the gate line are opposite to each other, and a selection signal is input to the gate line. It is preferable to include a control circuit that inverts the potential during the blanking period immediately before the selection and holds the potential for one vertical period after the selection signal is input.

The transflective liquid crystal display device according to the present invention is a transflective liquid crystal display device including a reflective display unit and a transmissive display unit, wherein a liquid crystal layer is sandwiched between an element substrate and a counter substrate, The element substrate includes a plurality of data lines, a plurality of gate lines, a plurality of switching elements arranged in pairs corresponding to each intersection of the data lines and the gate lines, and the pair of switching elements. A plurality of transmissive displays in which liquid crystal molecules are driven by applying an electric field between the pixel electrodes provided in the reflective display portion and the transmissive display portion respectively connected to each output end of the element, and the pixel electrodes A common electrode for reflection display, and the counter substrate has a common electrode for reflection display for driving liquid crystal molecules by applying an electric field between the pixel electrode and the common electrode for reflection display. Before the potential Potential of transmissive display common electrode is characterized by an inverse phase to each other.

Further, in the transflective liquid crystal display device according to the present invention, the reflective display common electrode for each gate line is connected to each other as a reflective display common electrode terminal outside the display region, and the transmissive liquid crystal for each gate line is connected. The display common electrode is connected to each other as a transmissive display common electrode terminal outside the display region, and the potential of the reflective display common electrode terminal and the potential of the transmissive display common electrode terminal are opposite to each other, and It is preferable that the potential is inverted every horizontal period.

Further, in the transflective liquid crystal display device according to the present invention, the odd-numbered reflective display common electrode and the even-numbered transparent display common electrode of the gate line are arranged at the first common electrode terminal outside the display region. The reflective display common electrode in the even-numbered row and the transmissive display common electrode in the odd-numbered row are connected to each other as a second common electrode terminal outside the display region, and the first common It is preferable that the potential of the electrode terminal and the potential of the second common electrode terminal are opposite to each other, and the potential is inverted every screen scan.

Further, in the transflective liquid crystal display device according to the present invention, the reflective display common electrode and the transmissive display common electrode are AC driven at a predetermined cycle, and when the potential is at a low potential,
It is preferable that a positive potential is supplied from the data line to the pixel electrode, and a negative potential is supplied from the data line to the pixel electrode when the potential is high.

In the transflective liquid crystal display device according to the present invention, the element substrate further includes a storage capacitor electrode for reflection display, which is provided in the reflection display unit and forms a storage capacitor with the pixel electrode. The potential of the reflective display holding capacitor electrode is preferably the same as the potential of the reflective display common electrode terminal.

In the transflective liquid crystal display device according to the present invention, the thickness of the liquid crystal layer may be such that the reflective display portion has a phase difference Δnd = λ / 4 and the transmissive display portion has a phase difference Δnd = λ / 2. preferable.

According to the transflective liquid crystal display device of the present invention, the potential of the reflective display common electrode in the reflective display unit and the potential of the transmissive display common electrode in the transmissive display unit are opposite to each other. Inversion does not occur between the reflective display portion and the reflective display portion, and good display can be performed.

Embodiments according to the present invention will be described below in detail with reference to the drawings. In the following, a liquid crystal display device using a FFS system for a transmissive display unit and having a color filter will be described, but it is of course possible to perform monochrome display. Moreover, it is good also as what takes the structure of systems other than FFS system, for example, an IPS system, as a horizontal electric field drive system.

Prior to the description of the configuration of the embodiment according to the present invention, in a transflective liquid crystal display device using a horizontal electric field driving method for a transmissive display unit and a vertical electric field driving method for a reflective display unit, the transmissive display unit is normally. A mechanism in which the white and reflective display portions are normally black will be described with reference to FIGS. Here, FIG. 1 to FIG. 3 are diagrams for explaining the configuration of the transflective liquid crystal display device 10 that uses the horizontal electric field driving method for the transmissive display portion and uses the vertical electric field driving method for the reflective display portion. Here, the vertical electric field driving method indicates a method of driving liquid crystal molecules by applying an electric field between the element substrate and the counter substrate. As a lateral electric field driving method, an FFS method is used in which liquid crystal molecules are driven by applying an electric field between a common electrode and a pixel electrode arranged on the same substrate with an insulating layer interposed therebetween.

FIG. 1 is a cross-sectional view of a portion of one subpixel in a transflective liquid crystal display device 10. Here, for example, when performing color display with R, G, and B, the sub-pixel refers to each display portion corresponding to R, G, and B. In the present example, the sub-pixel of R, Subpixel,
A unit of three subpixels of B is one pixel. The transflective liquid crystal display device 10 includes a transmissive display unit 12 and a reflective display unit 14. In the example of FIG. 1, the transflective liquid crystal display device 10 is sandwiched between a backlight 16, an element substrate 20 that is a first substrate, a counter substrate 60 that is a second substrate, and the element substrate 20 and the counter substrate 60. A liquid crystal layer 50, an element substrate side polarizing plate 18 disposed between the backlight 16 and the element substrate 20, and a counter substrate side polarizing plate 19 disposed outside the counter substrate 60.

The counter substrate 60 is the side facing the user in the transflective liquid crystal display device 10. That is, the user visually recognizes the brightness and darkness due to the optical characteristics of the liquid crystal layer 50 from the counter substrate 60 side.
In FIG. 1, in the transmissive display unit 12, light from the backlight 16 passes through the element substrate side polarizing plate 18, the element substrate 20, the liquid crystal layer 50, the counter substrate 60, and the counter substrate side polarizing plate 19. To reach. Further, in the reflective display unit 14, external light is transmitted to the counter substrate side polarizing plate 19,
It reaches the liquid crystal layer 50 through the counter substrate 60, is reflected by the reflective electrode 38 of the element substrate 20, and reaches the user's eyes again through the liquid crystal layer 50, the counter substrate 60, and the counter substrate side polarizing plate 19.

The counter substrate 60 is configured by laminating several films. In the example of FIG. 1, the glass substrate 62 and the black matrix 6 are directed from the counter substrate side polarizing plate 19 side to the element substrate 20 side.
4, a color filter 66, a reflective region gap adjusting layer 68, a reflective display common electrode 70 that is a common electrode in the reflective display unit 14, and a spacer 72. Since these materials, dimensions, forming methods, and the like can be used as a general method for manufacturing an active matrix liquid crystal display device, detailed description thereof is omitted.

Here, since the optical path of the reflective display unit 14 is double the optical path of the transmissive display unit 12, the reflective region gap adjusting layer 68 performs half-wave (λ / 2) light modulation in the transmissive display mode. The mode is provided to use quarter-wave (λ / 4) light modulation. As shown in FIG. 1, the liquid crystal layer 5 of the reflective display unit 14 is provided by providing the reflective region gap adjusting layer 68.
There is a difference between the thickness of 0 and the thickness of the liquid crystal layer 50 of the transmissive display unit 12. The thickness of the liquid crystal layer 50 is adjusted by the thickness of the reflective region gap adjusting layer 68 so that the reflective display unit 14 has a phase difference Δnd = λ / 4 and the transmissive display unit 12 has a phase difference Δnd = λ / 2. Is done. This reflection region gap adjustment structure is also used in the embodiment of the present invention.

The element substrate 20 is also referred to as an element-side substrate, a TFT substrate, or a TFT-side substrate, and is a substrate on the side where the switching element is disposed, and is a substrate for the counter substrate 60. Element substrate 20
A plurality of films patterned into a multi-layer structure by a well-known film forming technique and a pattern forming technique are stacked.

In the example of FIG. 1, the glass substrate 22 is directed from the backlight 16 side toward the liquid crystal layer 50 side.
The semiconductor layer 24, the gate insulating film 26, the gate electrode 28, the interlayer insulating film 30, the source / drain electrodes 32 and 33, the insulating film 34, the common electrode 42, the FFS insulating film 40, the reflective electrode 38, and the pixel electrode 36 are sequentially formed. Has been. Since these materials, dimensions, forming methods, and the like can be used as a general method for manufacturing an active matrix liquid crystal display device, detailed description thereof is omitted.

Here, the configuration related to the FFS system in the transmissive display unit 12 includes a common electrode 42 formed on the insulating film 34 and a pixel electrode 36 disposed on the common electrode 42 via the FFS insulating film 40. is there. A slit 37 is provided in the pixel electrode 36, and an electric field is applied between the common electrode 42 and the pixel electrode 36 by the slit 37, and the liquid crystal layer 50 is driven by the horizontal electric field method.

On the other hand, the configuration related to the vertical electric field driving method in the reflective display unit 14 is also the common electrode 42 formed on the insulating film 34 and the pixel electrode 36 disposed on the common electrode 42 via the FFS insulating film 40. However, the place where the reflective electrode 38 is arranged is different. Here, the reflective electrode 38 is formed after the common electrode 42 is formed and the FFS insulating film 40 is formed, and is connected to the pixel electrode 36 thereafter. The reflective electrode 38 is a conductive reflective film having a function of reflecting light from the counter substrate 60 side back to the counter substrate 60 side. Further, the common electrode 42 and the pixel electrode 36 have a function of forming a storage capacitor for driving the liquid crystal layer 50 through the FFS insulating film 40 therebetween.

Although not shown in FIG. 1, an alignment film is provided on the common electrode 42.
An alignment film is similarly provided on the surface of the counter substrate 60 facing the liquid crystal layer 50.

FIG. 2 is a plan view corresponding to the cross-sectional view of FIG. Here, a state in a process in the middle of the stacked structure of the element substrate 20 is sequentially shown for one pixel including three subpixels. FIG. 1 corresponds to a cross-sectional view taken along line AA shown in FIG. FIG.
(A) shows the state when the insulating film 34 is formed on the source / drain electrodes 32 and 33 and the contact hole is opened, and (b) shows the state when the common electrode 42 and the reflective electrode 38 are further formed. A state (c) shows a state at the time when the pixel electrode 36 having the slit 37 is formed. In the example of FIG. 2, the common electrode 42 is shown to be formed across a plurality of pixels. However, in some cases, the common electrode 42 may be separated for each sub-pixel. However, an auxiliary wiring for supplying a potential to each common electrode is required.

FIG. 3 is a diagram showing a relationship with the reflective display common electrode 70 on the counter substrate. The reflective display common electrode 70 is disposed on the counter substrate so as to face the reflective display portion 14.

Referring back to FIG. 2A, the gate line 29 and the data line 31 are wired so as to be orthogonal to each subpixel, and the switching element 25 is disposed at the intersection. The gate line 29 is located at the switching element 25 and the gate electrode 2 shown in FIG.
The data line 31 is connected to the source / drain electrode 32 shown in FIG. As described above, the transflective liquid crystal display device 10 is a so-called active matrix liquid crystal display device in which the switching elements 25 are respectively arranged at the intersections of the plurality of gate lines 29 and the plurality of data lines 31. Note that the gate line 29 is also called a scanning line, a scanning line, or a scanning signal line, and the data line 31 is also called a signal line, a signal line, a video signal line, a video signal line, or the like.

The switching element 25 includes a gate insulating film 26 formed on the semiconductor layer 24 shown in FIG. 1, a gate electrode 28 provided on the gate insulating film 26, and source / drain connected to the source / drain electrodes 32 and 33. For example, TFT (Thi
n Film Transistor) or the like. Switching element 2
One of the source / drain 5 is connected to the data line 31, for example, and the other is connected to the pixel electrode 36. Since the drain and the source are compatible, the source may be connected to the data line 31 and the drain may be connected to the pixel electrode 36. When the gate line 29 is selected, the switching element 25 conducts between the drain and the source, and the video signal from the data line 31 connected to the drain in the above example is supplied to the pixel electrode 36.

The display of the transflective liquid crystal display device 10 having the above configuration will be described below. Here, the relationship between the polarization axis of the polarizing plate and the alignment axis of the liquid crystal molecules is usually set as follows. That is,
The two polarizing plates outside the glass substrates 22 and 62, that is, the element substrate side polarizing plate 18 and the counter substrate side polarizing plate 19 are so that the polarizing axes are orthogonal to each other, and the polarizing axis of either polarizing plate is The liquid crystal layer 50 is set to be 45 degrees with the alignment axis of the liquid crystal molecules in a state where the driving voltage to the liquid crystal layer 50 is turned off. In the state where the drive voltage is turned on, the alignment axis of the liquid crystal molecules in the transmissive display unit 12 is configured to be parallel to the polarization axis. On the other hand, the liquid crystal molecules in the reflective display unit 14 are configured to rise perpendicularly to the surfaces of the glass substrates 22 and 62 in a state where the drive voltage is turned on.

With this configuration, in the transmissive display unit 12, when the drive voltage is off, the backlight 16
The incident light from the light passes through the element substrate side polarizing plate 18 and becomes linearly polarized light. When the light passes through the liquid crystal layer 50, a phase difference of λ / 2 is generated, and becomes linearly polarized light rotated by 90 degrees to be opposed substrate side polarized light. Board 19
Passes through and becomes white display (normally white). Here, as described above, in the transmissive display unit 12, the thickness of the liquid crystal layer 50 is adjusted to be the phase difference Δnd = λ / 2.
When the drive voltage is on, no phase difference is generated even if it passes through the liquid crystal layer 50, so that the incident linearly polarized light is absorbed by the counter substrate side polarizing plate 19 and a black display is obtained.

On the other hand, in the reflective display unit 14 in which the thickness of the liquid crystal layer 50 is adjusted to be Δnd = λ / 4, the following is obtained. When the incident light passes through the counter-substrate-side polarizing plate 19 and becomes linearly polarized light, when the driving voltage is off, a light having a phase difference of λ / 4 is generated when passing through the liquid crystal layer 50, and the light is clockwise. Circularly polarized light. Then, it is reflected by the reflective electrode 38 to become counterclockwise circularly polarized light, passes through the liquid crystal layer 50 again, becomes linearly polarized light rotated by 90 degrees, and is absorbed by the counter substrate side polarizing plate 19 to display black (normally black). . When the drive voltage is on, the liquid crystal molecules rise perpendicularly to the surfaces of the glass substrates 22 and 62, so that incident light does not cause a phase difference when passing through the liquid crystal layer 50, so that the reflected light is linearly polarized light. The counter substrate side polarizing plate 1 is returned as it is.
Passes 9 and becomes white.

Thus, in the transmissive display unit 12 and the reflective display unit 14, the change in transmittance is reversed with respect to the drive voltage, that is, the liquid crystal applied voltage. That is, in the normally state in which the drive voltage is off, the transmissive display unit 12 displays white, so-called normally white, while the reflective display unit 14 displays black, so-called normally black. When the drive voltage is on,
On the contrary, the transmissive display unit 12 displays black, while the reflective display unit 14 displays white. In this way, display inversion occurs between the transmissive display unit 12 and the reflective display unit 14 in the same subpixel. This is the problem of the transflective liquid crystal display device using the horizontal electric field drive method for the transmissive display portion and the vertical electric field drive method for the reflective display portion described in the prior art, and is also a problem of the present invention.

Here, a driving method of the liquid crystal display device will be described. FIG. 4 is an equivalent circuit of a pixel. Here, in this case, the pixel indicates one subpixel. Below, it demonstrates using the code | symbol of FIGS. 1-3. As described above, the sub-pixel which is a pixel is a pixel in which the switching element 25 is arranged at the intersection of the gate line 29 indicated as Gate and the data line 31 indicated as Video, and is connected to the output terminal of the switching element 25. A capacitance is formed between the electrode 36 and the common electrode 42. In FIG. 4, the storage capacitor in the transmissive display unit 12 is represented by TC _SC ,
The liquid crystal capacitor TC _LC, is shown a storage capacitor in the reflective display unit 14 RC _SC, the liquid crystal capacitance as RC _LC. The storage capacitors TC _SC and RC _SC are formed between the pixel electrode 36 and the common electrode 42 via the FFS insulating film 40.

In this equivalent circuit, when the gate line 29 is selected by a drive circuit (not shown), the switching element 25 is turned on, and each of the capacitors TC _SC , TC _LC , RC _SC , RC _LC is common to the data line 31. Charges corresponding to the potential difference between the electrodes 42 are accumulated, and an electric field corresponding to the potential difference between the pixel electrode 36 and the common electrode 42 is applied to the liquid crystal layer 50 in each subpixel region. In the holding period when the gate line 29 is not selected, the potential of the pixel electrode 36 is held by these capacitors TC _SC , TC _LC , RC _SC , RC _LC .

In the liquid crystal display device, in order to suppress display deterioration due to image sticking, the video signal voltage on the high potential side (positive polarity) and the video signal voltage on the low potential side (negative polarity) with respect to the common potential that is the potential of the common electrode 42. ) Is alternately input as a pixel potential which is the potential of the pixel electrode 36 at a predetermined cycle. That is, the liquid crystal layer 50 is AC driven. The following two methods can be used as the AC driving method for the liquid crystal layer 50.

One is to fix the potential of the common electrode 42 to a predetermined value and to change the video signal voltage applied to the pixel electrode 36 from positive polarity to negative polarity, which is called a common electrode DC driving method. . The other is to change the common electrode potential between a high potential and a low potential in a predetermined cycle, which is called a common electrode AC driving method. In this case, when the common electrode potential is high, a negative potential is used as the video signal voltage. Conversely, when the common electrode potential is low, a positive potential is used as the video signal voltage. . In general, the common electrode AC
Compared with the common electrode DC driving method, the driving method can reduce the output amplitude of the video signal, suppress the power consumption of the circuit, and reduce the cost of the circuit.

Also, the method of inverting the video signal voltage between positive polarity and negative polarity in one vertical period cycle is called the frame inversion driving method, and the video signal voltage is inverted between positive polarity and negative polarity in one horizontal period cycle. This method is called the H line inversion driving method.

Here, by using the common electrode AC driving method and further using the H-line inversion driving method, it is possible to suppress image sticking and the like, to reduce the video signal amplitude, and to suppress screen roughness by averaging the display screen. it can. Therefore, unless otherwise specified, the following description will be made assuming that the common electrode AC driving method is used and the H line inversion driving method is further used.

Embodiments of the present invention will be described below. In the following, the same elements as those described in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 5 is a diagram for explaining the basic concept of the embodiment of the present invention. That is, the common electrode is separated between the transmissive display unit 12 and the reflective display unit 14 so that independent potentials can be applied to each of them. Specifically, when the common electrode for the transmissive display unit 12 is referred to as a transmissive display common electrode 42 and the common electrode for the reflective display unit 14 is referred to as a reflective display common electrode 70, the transmissive display common electrode 42 is common. The potential of the electrode 42 and the potential of the reflective display common electrode 70 are opposite to each other. In FIG. 5, the transmissive display common electrode 42 is shown as COM and the reflective display common electrode 70 is shown as XCOM. Here, X indicates a reverse phase.

Here, the mutually opposite phases indicate a relationship in which one is at a high potential when one is at a low potential, and conversely, the other is at a high potential when one is at a low potential. The magnitude of one voltage amplitude may be different from the magnitude of the other voltage amplitude. Also, the center voltage of one voltage amplitude may be different from the center voltage of the other voltage amplitude.

As described above, the change in the common potential when the potential of the common electrode for transmissive display and the potential of the common electrode for reflective display are independent from each other, and the display state of the transmissive display unit and the reflective display unit. FIG. 6 shows the correspondence between the display states. Here, the potential of the transmissive display common electrode COM which is a common electrode of the transmissive display portion and the potential of the reflective display common electrode XCOM which is the common electrode of the reflective display portion are in opposite phases. The same video signal is supplied to both the transmissive display unit and the reflective display unit.

For example, consider a transflective liquid crystal display device in which the transmissive display unit 12 is set to normally white and the reflective display unit 14 is set to normally black as described above. Here, when the potential of the transmissive display common electrode COM is at a low potential, that is, at COM-L, and the pixel electrode potential is at a high potential, the liquid crystal application voltage becomes large, so that the drive voltage is turned on. Corresponds to the state, black display. At this time, at the same time, the potential of the reflective display common electrode XCOM is at a high potential, that is, XCOM-H. Accordingly, since the liquid crystal application voltage is small, it corresponds to a state in which the drive voltage is off and black display is obtained. Similarly, when the pixel electrode potential is low, white display is performed in both the transmissive display portion and the reflective display portion. Similarly, when the display is in COM-H or XCOM-L at another time, similarly, when the transmissive display portion is white, the reflective display portion is also white, and when the transmissive display portion is black, the reflective display portion is also Black display.

In this way, in the transflective liquid crystal display device using the lateral electric field driving method, the transmissive display common electrode potential and the reflective display common electrode potential are independent from each other and opposite to each other. Good display can be performed without inversion of display between the display portion and the reflective display portion. In the above description, the case where the transmissive display unit 12 is normally white and the reflective display unit 14 is normally black has been described. However, the same applies when the transmissive display unit 12 is normally black and the reflective display unit 14 is normally white. It is. In the following, an example of a specific configuration under this basic principle will be described.

When a common potential of opposite phase is supplied to the transmissive display unit and the reflective display unit, the voltage applied to the liquid crystal layer changes every horizontal period, which may affect display quality in some cases. Therefore, if two switching elements are provided in one subpixel, pixel electrodes can be made independent in the transmissive display portion and the reflective display portion, and the voltage applied to the liquid crystal layer can be made more constant when the common potential is inverted. FIG. 7 is a diagram showing this state. In the following, the same elements as those described in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed description thereof will be omitted, and will be described using the reference numerals of FIGS. 1 to 6. Here, two switching elements 23 and 25 are provided for one gate line 29, and one switching element 23 is for the transmissive display unit 12, and its output terminal is connected via the capacitor TC of the transmissive display unit 12. Connected to the transmissive display common electrode 42;
Other switching element 25 is its output by way of the reflective display unit 14 is connected to a storage capacitor electrode 41 for reflective display through the storage capacitor RC _SC of the reflective display unit 14, also, the liquid crystal capacitance RC _LC
To the reflective display common electrode 70 of the counter substrate 60.

FIG. 8 is a diagram showing a configuration relating to display driving of a transflective liquid crystal display device in which a switching element for a transmissive display unit and a switching element for a reflective display unit are provided in one subpixel. In the following, the same elements as those described in FIGS. 1 to 7 are denoted by the same reference numerals, detailed description thereof will be omitted, and description will be made using the reference numerals of FIGS. 1 to 7. Here, a switching element 23 for the transmissive display unit 12 and a switching element 25 for the reflective display unit 14 are provided for each sub-pixel, and a transmissive display for the transmissive display unit 12 is provided for each gate line 29. The common electrode 42 and the reflective display storage capacitor electrode 41 for the reflective display unit 14 are respectively provided in the display region 80.
It is drawn out to the outside and is guided to the common electrode control circuit 88.

The transmissive display common electrode 42 for each gate line is connected to each other outside the display region 80 to serve as a transmissive display common electrode terminal 90. Similarly, the reflective display storage capacitor electrodes 41 for each gate line are connected to each other outside the display region 80 to serve as a reflective display storage capacitor electrode terminal 91. In FIG. 8, the transmissive display common electrode terminal 90 is shown as TCOM, and the reflective display storage capacitor electrode terminal 91 is shown as RCOM. These have names of terminals, but may be simply connected.

Similarly, the reflective display common electrode 70 is also drawn out of the display region 80 and connected to the element substrate 20 side by a contact pad shown as a reflective display common electrode contact 89. Specifically, as shown in FIG. 8, the reflective display storage capacitor electrode terminal 91 and the reflective display common electrode 70 are connected.

FIG. 9 is a timing chart in the configuration of FIG. FIG. 9 shows changes in the potential of each gate line and changes in the potential of the transmissive display common electrode terminal TCOM and the potential of the reflective display common electrode terminal RCOM. In the following, the same elements as those described in FIGS. 1 to 8 are denoted by the same reference numerals, detailed description thereof will be omitted, and description will be made using the reference numerals of FIGS. 1 to 8.

The potential of the transmissive display common electrode terminal TCOM and the potential of the reflective display common electrode terminal RCOM change as a set for each horizontal period. For example, the potential is inverted during the blanking period immediately before the selection signal is input to “Gate N”, and the potential is held for one horizontal period even after the selection signal is input. Further, the potential of the pair of transmissive display common electrode terminals TCOM and the potential of the reflective display common electrode terminals RCOM are in opposite phases.

Note that the polarity of the video signal is inverted every horizontal period in accordance with the gate selection. For example, it is assumed that “Gate N” is selected and a negative video signal is input to the transmissive display unit corresponding to the gate line. At this time, the corresponding reflective display unit is in the positive polarity writing mode because the common electrode potential is in the opposite phase. Next, when “Gate N + 1” is selected, a positive video signal is input to the transmissive display unit corresponding to the gate line.
At this time, the corresponding reflective display section is in negative polarity writing because the common electrode potential is in reverse phase.

By operating the common electrode control circuit 88 in such a timing chart, a good display can be performed without causing inversion of display between the transmissive display unit 12 and the reflective display unit 14 while performing H line inversion driving. It can be carried out.

10 to 12 are a cross-sectional view and a plan view of a transflective liquid crystal display device 110 using the configuration of FIG. In the following, the same elements as those described in FIGS. 1 to 9 are denoted by the same reference numerals and detailed description thereof will be omitted, and will be described using the reference numerals of FIGS. 1 to 9. FIG. 10 is a cross-sectional view of one subpixel of the transflective liquid crystal display device 110, and corresponds to FIG. Here, two switching elements 23 and 25 are provided for one subpixel. The switching element 23 is for the transmissive display unit 12, and the switching element 25 is for the reflective display unit 14.

Since the configuration of the transflective liquid crystal display device 110 is the same as that described in FIG. 1 except for the element substrate 120, the structure of the element substrate 120 will be described below. On the element substrate 120,
A plurality of films patterned in a multilayer structure are stacked. In the example of FIG. 10, the glass substrate 22, the semiconductor layer 24, the gate insulating film 26, the gate electrode 28, the interlayer insulating film 30, and the source / drain electrodes 33 and 35 from the backlight 16 side toward the liquid crystal layer 50 side. , Insulating film 34
, First transparent conductive films 36 and 41, FFS insulating film 40, reflective electrode 38, second transparent conductive film 42,
44 are sequentially formed. Since these materials, dimensions, forming methods, and the like can be used as a general method for manufacturing an active matrix liquid crystal display device, detailed description thereof is omitted.

Here, the first transparent conductive films 36 and 41 are divided by the transmissive display unit 12 and the reflective display unit 14. The transmissive display unit 12 functions as the pixel electrode 36 in the FFS method, and the reflective display unit 14 functions as the storage capacitor electrode 41 for reflective display in the vertical electric field driving method.

The second transparent conductive films 42 and 44 are divided by the transmissive display unit 12 and the reflective display unit 14. The transmissive display unit 12 functions as the common electrode 42 in the FFS system, and the reflective display unit 1
4 functions as the pixel electrode 44 in the vertical electric field driving method.

Therefore, the configuration related to the FFS method in the transmissive display unit 12 includes the insulating film 34.
The first transparent conductive film 36 formed on the first transparent conductive film 36 becomes the pixel electrode 36, and the second transparent conductive film 42 disposed on the first transparent conductive film 36 via the FFS insulating film 40 becomes the common electrode 42. A slit 43 is provided in the common electrode 42, and an electric field is applied between the common electrode 42 and the pixel electrode 36 by the slit 43, and the liquid crystal layer 50 is driven by the horizontal electric field method.

On the other hand, in the configuration relating to the vertical electric field driving method in the reflective display unit 14, the first transparent conductive film 41 formed on the insulating film 34 becomes the reflective display storage capacitor electrode 41, and is formed on the first transparent conductive film 41. The second transparent conductive film 44 disposed via the FFS insulating film 40 becomes the pixel electrode 44. A reflective electrode 38 is disposed. The reflective electrode 38 is formed after the first transparent conductive film 41 is formed and the FFS insulating film 40 is formed, and is connected to the subsequent second transparent conductive film 44. The reflective electrode 38 is a conductive reflective film having a function of reflecting light from the counter substrate 60 side back to the counter substrate 60 side. The reflective display storage capacitor electrode 41 and the pixel electrode 44 have a function of forming a storage capacitor for driving the liquid crystal layer 50 through the FFS insulating film 40 therebetween. Here, as in FIG. 1, the alignment film is not shown.

FIG. 11 is a plan view showing a specific configuration. Here, two switching elements 23,
25 shows a state in which two pixel electrodes, a common electrode, and a storage capacitor electrode for reflection display are formed correspondingly. In FIG. 11A, after the two switching elements 23 and 25 are formed corresponding to the transmissive display unit 12 and the reflective display unit 14, respectively, and the corresponding source / drain electrodes 33 and 35 are formed, These show the situation when two contact holes and the like are opened. FIG. 5B shows the first transparent conductive films 36 and 41 further including the transmissive display portion 1.
2 is formed as the reflective display storage capacitor electrode 41 of the reflective display unit 14 and then the reflective electrode 38 is formed, (c) shows the second transparent conductive films 42 and 44 being the transmissive display unit. The state at the time of being formed as the 12 common electrodes 42 and the pixel electrode 44 of the reflective display unit 14 is shown.

Here, as shown in FIG. 11B, the reflective display storage capacitor electrode 4 of the reflective display unit 14.
1 is drawn to the outside of the display area. Similarly, as shown in FIG. 11C, the common electrode 42 of the transmissive display unit 12 is drawn to the outside of the display area 80, as described in FIG. A predetermined connection is made in the common electrode control circuit 88 outside the display region 80.

A modification of FIG. 11C is shown in FIG. As the transparent conductive film used for the common electrode and the pixel electrode, ITO (Indium Titanium Oxide) or IZO (Indium Zinc Oxide) is used. However, since these generally have high resistance, the common electrode is placed outside the display area. When it is pulled out, the resistance value may become a problem. On the other hand, aluminum, an aluminum alloy, silver, etc. are used for a reflective electrode, and resistance value is low compared with ITO and IZO. Therefore, the reflective electrode is preferably used to reduce the resistance of the common electrode.

FIG. 12 shows a state in which the leader line 47 made of the same material as the reflective electrode is arranged in the transmissive display unit 12. By doing so, it is possible to reduce the resistance when the common electrode 42 is drawn outside the display area.

13 and 14 are a cross-sectional view and a plan view of another example of the transflective liquid crystal display device 110 using the configuration of FIG. In the following, the same elements as those described in FIGS. 1 to 12 are denoted by the same reference numerals, detailed description thereof will be omitted, and description will be made using the reference numerals of FIGS. FIG. 13 is a cross-sectional view of one transpixel of the transflective liquid crystal display device 111, and corresponds to FIG. Here, as described with reference to FIG. 10, the switching element 23 for the transmissive display unit 12 and the switching element 25 for the reflective display unit 14 are provided for one subpixel.

The transflective liquid crystal display device 111 is different from the transflective liquid crystal display device 110 described with reference to FIG. 10 in the arrangement and usage of the first transparent conductive film and the second transparent conductive film of the element substrate 121.
Since the other configuration is the same as that described in FIG. 10, the configuration of the element substrate 121 will be described below. On the element substrate 121, a plurality of films patterned in a multilayer structure are stacked. In the example of FIG. 13, from the backlight 16 side toward the liquid crystal layer 50 side, the glass substrate 22, the semiconductor layer 24, the gate insulating film 26, the gate electrode 28, the interlayer insulating film 30, and the source / drain electrodes 33, 35. , Insulating film 34, first transparent conductive films 42 and 41, FFS insulating film 40
The reflective electrode 38 and the second transparent conductive films 36 and 44 are sequentially formed. Since these materials, dimensions, forming methods, and the like can be used as a general method for manufacturing an active matrix liquid crystal display device, detailed description thereof is omitted.

Here, the first transparent conductive films 42 and 41 are divided by the transmissive display unit 12 and the reflective display unit 14. That is, the transmissive display unit 12 functions as the common electrode 42 in the FFS method, and the reflective display unit 14 functions as the reflective display storage capacitor electrode 41 in the vertical electric field driving method.

The second transparent conductive film is divided between the transmissive display unit 12 and the reflective display unit 14, but both are used as the pixel electrodes 36 and 44. That is, the transmissive display unit 12 functions as the pixel electrode 36 in the FFS method, and the reflective display unit 14 has the pixel electrode 44 in the vertical electric field drive method.
Function as.

Therefore, the configuration related to the FFS method in the transmissive display unit 12 includes the insulating film 34.
The first transparent conductive film 42 formed on the first transparent conductive film 42 becomes the common electrode 42, and the second transparent conductive film 36 disposed on the first transparent conductive film 42 via the FFS insulating film 40 becomes the pixel electrode 36. The pixel electrode 36 is provided with a slit, and the common electrode 42 and the pixel electrode 36 are formed by the slit.
An electric field is applied between the liquid crystal layer 50 and the liquid crystal layer 50 is driven by the horizontal electric field method.

On the other hand, in the configuration relating to the vertical electric field driving method in the reflective display unit 14, the first transparent conductive film 41 formed on the insulating film 34 becomes the reflective display storage capacitor electrode 41, and is formed on the first transparent conductive film 41. The second conductive film 44 disposed via the FFS insulating film 40 becomes the pixel electrode 44.
A reflective electrode 38 is disposed. The reflective electrode 38 forms the first transparent conductive film 41 and FF
It is formed after the S insulating film 40 is formed and is connected to the subsequent second transparent conductive film 44. The reflective electrode 38 is a conductive reflective film having a function of reflecting light from the counter substrate 60 side back to the counter substrate 60 side. The reflective display storage capacitor electrode 41 and the pixel electrode 44 have a function of forming a storage capacitor for driving the liquid crystal layer 50 through the FFS insulating film 40 therebetween. Here, as in FIG. 10, the alignment film is not shown.

FIG. 14 is a plan view showing a specific configuration, corresponding to FIGS. 11B and 11C, and FIG.
As described above, two switching elements 23 and 25 are formed, and two pixel electrodes and two common electrodes are formed correspondingly. In FIG. 14A, the first transparent conductive films 42 and 41 are formed as the common electrode 42 of the transmissive display unit 12 and the reflective display storage capacitor electrode 41 of the reflective display unit 14, and then the reflective electrode 38 is formed. The state at the time, (b) shows the second transparent conductive films 36 and 44 with the pixel electrode 36 of the transmissive display unit 12 and the pixel electrode 4 of the reflective display unit 14.
The state at the time of being formed as 4 is shown.

Here, as shown in FIG. 14B, the common electrode 42 of the transmissive display unit 12 and the reflective display storage capacitor electrode 41 of the reflective display unit 14 are both pulled out to the outside of the display region 80.
As described above, a predetermined connection is made in the common electrode control circuit 88 outside the display region 80.

In the example of the third embodiment, the common electrode potential is inverted every horizontal period. Therefore, 1
As the horizontal period becomes shorter, the effects of rise time and fall time during inversion tend to appear. Therefore, since this problem is a common problem even in the driving method of a general liquid crystal display device, for example, an independent common electrode line for each row of gate lines in the display area, For example, Japanese Laid-Open Patent Publication No. 2001-356356 proposes a method in which lines are connected to each other and a common electrode potential signal that is inverted every vertical period is input. Here, the common electrode potential of those connected by even lines and the common electrode potential of those connected by odd lines are opposite in phase. The inversion of the common electrode potential is performed in one vertical period, that is, every screen scan as described above. Here, the independent common electrode wiring refers to an independent wiring for each pixel.

FIG. 15 is a diagram showing a configuration in which the above proposal is changed to be applicable to a transflective liquid crystal display device, and corresponds to FIG. In the following, the same elements as those described with reference to FIGS. 1 to 14 are denoted by the same reference numerals, and the description will be made with reference to the reference numerals of FIGS. here,
The odd-numbered reflective display holding capacitor electrodes 41 and the even-numbered transmissive display common electrodes 42 of the gate lines 29 are connected to each other as the first common electrode terminals 94 outside the display region 80. The reflective display holding capacitor electrode 41 and the odd-numbered transmissive display common electrode 42 are connected to each other as the second common electrode terminal 95 outside the display region 80.

In the case of FIG. 15, as in FIG. 8, for each gate line 29, a transmissive display common electrode 42 for the transmissive display unit 12 and a reflective display storage capacitor electrode 41 for the reflective display unit 14 are provided. Each is drawn out of the display area 80 and led to the common electrode control circuit 92. The even and odd numbers are relative, and in the case of FIG. 15, the first common electrode terminal 94 is in the first row, 3
The storage capacitor electrodes 41 for reflective display in the rows, the fifth row, etc. and the transmissive display common electrodes 42 in the second row, the fourth row, the sixth row, etc. are connected to each other, and the second common electrode terminal 95 is the second line, the fourth line,
The reflective display holding capacitor electrodes 41 in the sixth row and the like, and the transmissive display common electrodes 42 in the first row, the third row, the fifth row, and the like are connected to each other. In FIG. 15, the first common electrode terminal 94 is COM.
And the second common electrode terminal 95 is shown as XCOM.

Similarly, the reflective display common electrode 70 is also drawn out of the display area 80 corresponding to each gate line 29 and corresponding to the first common electrode terminal 94 and the second common electrode terminal 95 described above. The first common electrode terminal 71 for reflective display corresponding to the odd-numbered gate lines 29 and the second common electrode terminal 73 for reflective display corresponding to the even-numbered gate lines 29 are combined into the common electrode contact 96 for reflective display. The device substrate 20 is shown by a contact pad shown as 97
Connected to the side. Specifically, as shown in FIG. 15, the first common electrode terminal 94 has a first reflective display common electrode terminal 71, the second common electrode terminal 95 has a second reflective common electrode terminal 73,
Each is connected.

FIG. 16 is a timing chart in the configuration of FIG. 15 and corresponds to FIG.
In FIG. 16, the change of the potential of each gate line and the change of the potential of the first common electrode terminal COM and the potential of the second common electrode terminal XCOM are shown. In the following, the same elements as those described in FIGS. 1 to 15 are denoted by the same reference numerals, detailed description thereof will be omitted, and description will be made using the reference numerals of FIGS. 1 to 15.

The potential of the first common electrode terminal COM and the potential of the second common electrode terminal XCOM are set as one set,
It changes every vertical period, that is, every screen scan. And, for example, “Gate 1
The potential is inverted during the blanking period immediately before the selection signal is input to “,” and the potential is maintained for one vertical period after the selection signal is input. Further, the potential of the pair of first common electrode terminals COM and the potential of the second common electrode terminal XCOM are opposite in phase to each other.

Note that the polarity of the video signal is inverted every horizontal period in accordance with the gate selection. For example, it is assumed that “Gate 1” is selected and a negative video signal is input to the transmissive display unit corresponding to the gate line. At this time, the corresponding reflective display unit is in the positive polarity writing mode because the common electrode potential is in the opposite phase. Next, when “Gate 2” is selected, a positive video signal is input to the transmissive display unit corresponding to the gate line. At this time, the corresponding reflective display section is in negative polarity writing because the common electrode potential is in reverse phase.

By operating the common electrode control circuit 92 in such a timing chart, a good display can be performed without causing inversion of display between the transmissive display unit 12 and the reflective display unit 14 while performing H line inversion driving. it can.

It is sectional drawing of the transflective liquid crystal display device for demonstrating the mechanism in which the transmissive display part of a horizontal electric field drive is normally white, and the reflective display part of a vertical electric field drive is normally black. FIG. 2 is a plan view corresponding to FIG. 1. It is a top view corresponding to FIG. 1, and is a figure which shows the relationship with the common electrode for reflective displays. It is the equivalent circuit of the pixel in the liquid crystal display device of a prior art. 3 is an equivalent circuit of a pixel in the embodiment according to the present invention. In the transflective liquid crystal display device according to the embodiment of the present invention, the horizontal axis represents the correspondence between the change in the common potential and the display state of the transmissive display unit and the display state of the reflective display unit. . 3 is an equivalent circuit of a specific pixel in the embodiment according to the present invention. In an embodiment concerning the present invention, it is a figure showing composition about display drive of a transflective liquid crystal display. 9 is a timing chart of common electrode potentials corresponding to the configuration of FIG. 1 is a cross-sectional view of a transflective liquid crystal display device according to an embodiment of the present invention. It is a top view corresponding to FIG. It is a figure which shows the modification of FIG. In embodiment which concerns on this invention, it is sectional drawing of the transflective liquid crystal display device of another structure. FIG. 14 is a plan view corresponding to FIG. 13. In other embodiment, it is a figure which shows the structure regarding the display drive of a transflective liquid crystal display device. It is a timing chart of the common electrode potential corresponding to the configuration of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110,111 ... Semi-transmissive liquid crystal display device, 12 ... Transmission display part, 14 ... Reflection display part, 16 ... Backlight, 18 ... Element substrate side polarizing plate, 19 ... Opposite substrate side polarizing plate, 20, 12
0, 121 ... element substrate, 22, 62 ... glass substrate, 23, 25 ... switching element, 24
... Semiconductor layer, 26 ... Gate insulating film, 28 ... Gate electrode, 29 ... Gate line, 30 ... Interlayer insulating film, 31 ... Data line, 32, 33, 35 ... Source / drain electrode, 34 ... Insulating film, 36, 44 ... Pixel electrode (transparent conductive film), 37, 43 ... Slit, 38 ... Reflective electrode, 40
DESCRIPTION OF SYMBOLS: FFS insulating film, 41 ... Reflective display holding capacitor electrode (transparent conductive film), 42 ... Common electrode (transparent conductive film), 47 ... Lead wire, 50 ... Liquid crystal layer, 60 ... Counter substrate, 62 ... Glass substrate, 64 ... Black matrix, 66 ... Color filter, 68 ... Reflection area gap adjustment layer, 70 ... Reflection display common electrode, 71, 73 ... Reflection display common electrode terminal, 72 ... Spacer, 80 ... Display area, 88, 92 ... Common Electrode control circuit 89, 96, 97 ... Reflective display common electrode contact, 90 ... Transparent display common electrode terminal, 91 ... Reflective display holding capacitor electrode terminal, 94 ... First common electrode terminal, 95 ... Second common electrode Terminal.

Claims (8)

A transflective liquid crystal display device comprising a liquid crystal layer sandwiched between an element substrate and a counter substrate and including a reflective display portion and a transmissive display portion,
The element substrate is
Multiple data lines and multiple gate lines;
A plurality of switching elements respectively disposed at each intersection of the data line and the gate line;
A plurality of pixel electrodes respectively connected to respective output ends of the plurality of switching elements;
A transmissive display common electrode for driving liquid crystal molecules by applying an electric field between the pixel electrode;
Have
The counter substrate is
A reflective display common electrode for driving liquid crystal molecules by applying an electric field between the pixel electrode and
The transflective liquid crystal display device, wherein the potential of the common electrode for reflective display and the potential of the common electrode for transmissive display are opposite to each other. The transflective liquid crystal display device according to claim 1,
The potential of the common electrode for reflective display and the common electrode for transmissive display that have the gate line in common are opposite to each other, and the potential is inverted during a blanking period immediately before a selection signal is input to the gate line, A transflective liquid crystal display device including a control circuit that holds a potential for one vertical period after a selection signal is input. A transflective liquid crystal display device comprising a liquid crystal layer sandwiched between an element substrate and a counter substrate and including a reflective display portion and a transmissive display portion,
The element substrate is
Multiple data lines and multiple gate lines;
A plurality of switching elements arranged in pairs corresponding to each intersection of the data line and the gate line;
A pixel electrode provided in each of the reflective display portion and the transmissive display portion connected to each output terminal of the pair of switching elements;
A plurality of transmissive display common electrodes in which liquid crystal molecules are driven by applying an electric field between the pixel electrodes;
Have
The counter substrate is
A reflective display common electrode for driving liquid crystal molecules by applying an electric field to the pixel electrode;
Have
The transflective liquid crystal display device, wherein the potential of the common electrode for reflective display and the potential of the common electrode for transmissive display are opposite to each other. The transflective liquid crystal display device according to claim 3,
The reflective display common electrode for each gate line is connected to each other as a reflective display common electrode terminal outside the display region;
The transmissive display common electrode for each gate line is connected to each other as a transmissive display common electrode terminal outside the display region,
The transflective liquid crystal display device, wherein the potential of the common electrode terminal for reflective display and the potential of the common electrode terminal for transmissive display are opposite to each other and are inverted every horizontal period. The transflective liquid crystal display device according to claim 3,
The reflective display common electrode in the odd-numbered row of the gate line and the common electrode for transmissive display in the even-numbered row are connected to each other as a first common electrode terminal outside the display region, and the reflection in the even-numbered row of the gate line is connected. The display common electrode and the transmissive display common electrode in the odd-numbered rows are connected to each other as a second common electrode terminal outside the display region,
The transflective liquid crystal display device, wherein the potential of the first common electrode terminal and the potential of the second common electrode terminal are opposite in phase to each other, and the potential is inverted every screen scan. The transflective liquid crystal display device according to any one of claims 1 to 5,
The reflective display common electrode and the transmissive display common electrode are AC driven in a predetermined cycle,
When the potential is low, a positive potential is supplied from the data line to the pixel electrode, and when the potential is high, a negative potential is supplied from the data line to the pixel electrode. A transflective liquid crystal display device. The transflective liquid crystal display device according to any one of claims 1 to 5,
The element substrate is
A reflective display storage capacitor electrode provided in the reflective display unit for forming a storage capacitor with the pixel electrode;
The transflective liquid crystal display device according to claim 1, wherein a potential of the storage capacitor electrode for reflective display is the same as a potential of the common electrode terminal for reflective display. The transflective liquid crystal display device according to any one of claims 1 to 7,
The thickness of the liquid crystal layer is such that the reflective display unit has a phase difference Δnd = λ / 4, and the transmissive display unit has a phase difference Δ.
A transflective liquid crystal display device, wherein nd = λ / 2.

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