JP5032010B2 - Liquid crystal display device and driving method thereof - Google Patents

Description

  The present invention relates to a liquid crystal display device and a driving method thereof, and more particularly to a liquid crystal display device that bends a liquid crystal material and a driving method thereof.

  In an optically compensated birefringence (OCB) mode liquid crystal display device, the liquid crystal layer retardation is changed by forming a bend alignment in the liquid crystal material and changing the tilt angle of the liquid crystal molecules in the vicinity of each alignment film. The OCB mode is one of the display modes that can realize excellent response speed and viewing angle characteristics, and has recently attracted attention.

  In an OCB mode liquid crystal display device, the liquid crystal material usually forms a splay alignment in an initial state before power-on. Therefore, when starting the display device, for example, a voltage is applied between adjacent pixel electrodes to generate a horizontal electric field, thereby causing a transition from the splay alignment to the twist alignment. Then, the entire liquid crystal layer is transferred from the splay alignment to the bend alignment using the portion where the twist alignment is formed as a transition nucleus.

  In order to cause this initial transition, a large voltage must be applied between adjacent pixel electrodes. In addition, the OCB mode liquid crystal display device has a higher dielectric constant of the liquid crystal layer than the TN (twisted nematic) mode liquid crystal display device. Further, the OCB mode liquid crystal display device is required to complete the initial transition within a certain time.

  Therefore, in the OCB mode liquid crystal display device, for example, a thin film transistor having a large channel width must be used as a switch in the pixel circuit, and there is a problem that the wiring load of the signal line and the scanning line is large. This problem is particularly noticeable when the liquid crystal display device has a large screen and high definition.

  An object of the present invention is to reduce the wiring load at the time of initial transition.

According to the first aspect of the present invention, an array substrate having a plurality of pixel circuits each including a pixel electrode and a first transition electrode, and a counter substrate having a counter electrode facing the pixel circuits, A liquid crystal layer interposed between the array substrate and the counter substrate , wherein each of the plurality of pixel circuits includes a first switch for switching a supply state of a video signal to the pixel electrode, and the first switch A second switch for switching a supply state of the transfer signal to the transfer electrode, and the array substrate includes a plurality of first and second scan lines arranged alternately, and a plurality of signal lines intersecting with the first and second scan lines. In each of the plurality of pixel circuits, the first switch is connected between the signal line and the pixel electrode, and the second switch is the same signal as that to which the first switch is connected. Connected between the first transition electrode and the liquid crystal switching operation of the first and second switches, characterized in that it is controlled by a scan signal supplied from the first and second scan line A display device is provided.

According to a second aspect of the present invention, there is provided a method for driving a liquid crystal display device according to the first aspect , wherein the liquid crystal layer includes a liquid crystal layer by writing a transition signal to the transition electrode when the liquid crystal display device is activated. A driving method is provided that induces a transition from a splay alignment to a bend alignment of the material.

  According to the present invention, it is possible to reduce the wiring load at the time of initial transition.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals are given to components that exhibit the same or similar functions, and duplicate descriptions are omitted.

  FIG. 1 is a plan view schematically showing a liquid crystal display device according to the first embodiment of the present invention. FIG. 2 is an enlarged plan view showing a part of the liquid crystal display device shown in FIG. 3 is a cross-sectional view taken along line III-III of the liquid crystal display device shown in FIG. FIG. 4 is an equivalent circuit diagram of the liquid crystal display device shown in FIG.

  The liquid crystal display device illustrated in FIGS. 1 to 4 is an OCB mode active matrix liquid crystal display device. This liquid crystal display device includes an active matrix drive type liquid crystal display panel DP, a printed circuit board (not shown), and a tape carrier package (not shown) in which they are electrically connected. The liquid crystal display device further includes a backlight unit (not shown) disposed so as to face the liquid crystal display panel DP. Here, as an example, it is assumed that the liquid crystal display panel DP has a diagonal size of the display area of 23 inches.

  As shown in FIG. 3, the liquid crystal display panel DP includes an array substrate AS and a counter substrate CS facing the array substrate AS. A frame-shaped adhesive layer (not shown) is interposed between the array substrate AS and the counter substrate CS. A plurality of transfer electrodes (not shown) for electrically connecting the array substrate AS and the counter substrate CS are disposed between the array substrate AS and the counter substrate CS and outside the frame formed by the adhesive layer. Has been placed. A space surrounded by the array substrate AS, the counter substrate CS, and the adhesive layer is filled with a liquid crystal material, and the liquid crystal material forms a liquid crystal layer LC. On each outer surface of the array substrate AS and the counter substrate CS, an optical compensation film (biaxial film) OC and a polarizing plate PLZ are sequentially arranged.

The array substrate AS includes a transparent substrate SUB1 such as a glass substrate.
On the substrate SUB1, as shown in FIGS. 1, 2, and 4, the first scanning lines SL1 and the second scanning lines SL2 each extending in the X direction are alternately arranged in the Y direction. The X direction and the Y direction are each parallel to the main surface of the substrate SUB1 and intersect each other. Here, as an example, it is assumed that the X direction and the Y direction are orthogonal to each other. Note that the Z direction shown in FIG. 3 is a direction orthogonal to the X direction and the Y direction. The scanning lines SL1 and SL2 are made of, for example, a metal or an alloy.

  The substrate SUB1 and the scanning lines SL1 and SL2 are covered with a gate insulating film (not shown). The gate insulating film is made of, for example, a light transmissive insulator such as silicon oxide.

  A patterned semiconductor layer SC is disposed on the portion of the gate insulating film covering the scanning lines SL1 and SL2. These semiconductor layers SC are, for example, amorphous silicon layers in which a channel and source / drain are formed. The portions of the scanning lines SL1 and SL2 that face the semiconductor layer SC of the gate insulating film and the semiconductor layer SC constitute a thin film transistor that is the switches SW1 and SW2. Here, as an example, the switches SW1 and SW2 are n-channel thin film transistors.

  The gate insulating film and the semiconductor layer SC are covered with the insulating film I1. The insulating film I1 is made of, for example, a light transmissive insulator such as silicon oxide or silicon nitride. The insulating film I1 is provided with a through hole at a position corresponding to the source / drain of the semiconductor layer SC.

  A signal line VL and a drain electrode DE are disposed on the insulating film I1. Each of the signal lines VL extends in the Y direction, and is arranged in the X direction corresponding to the column formed by the semiconductor layer SC. The signal line VL and the drain electrode DE fill the through hole provided in the insulating film I1, and are connected to the source and drain of the semiconductor layer SC, respectively. The signal line VL and the drain electrode DE are made of, for example, a metal or an alloy.

  The insulating film I1, the signal line VL, and the drain electrode DE are covered with the insulating film I2. The insulating film I2 is made of, for example, a light transmissive insulator such as silicon oxide or silicon nitride. A through hole is provided in the insulating film I2 at a position corresponding to the drain electrode DE.

  On the insulating film I2, the pixel electrode PE and the first transfer electrode TE1 are disposed. The pixel electrode PE fills a through hole provided in the insulating film I2, and is connected to the drain of the switch SW1 through the drain electrode DE. The first transfer electrode TE1 fills a through hole provided in the insulating film I2, and is connected to the drain of the switch SW2 via the drain electrode DE. The pixel electrode PE is made of a transparent conductor such as ITO (indium tin oxide). A metal or an alloy can be used as the material of the first transition electrode TE1, but typically, the same material as that of the pixel electrode PE is used.

  The first transition electrode TE1 typically has a smaller area than the pixel electrode PE. Here, as an example, it is assumed that the pitch in the X direction of the pixels PX is 130.5 μm and the pitch in the Y direction is 391.5 μm. Further, it is assumed that the pixel PX and the first transfer electrode TE1 have the same dimension in the X direction, and the first transfer electrode TE1 has a dimension in the Y direction of 20 μm.

  As shown in FIGS. 1 and 2, one of the two sides of the pixel electrode PE facing the first transition electrode TE1 has a wave shape such as a rectangular wave. Further, the side of the first transition electrode TE1 facing the side having the wave shape has a wave shape such as a rectangular wave. When starting up the liquid crystal display device, a voltage is applied between the pixel electrode PE and the first transition electrode TE1 to generate a lateral electric field in the vicinity of the side having the previous waveform, and from the splay alignment to the twist. Causes a transition to orientation. Then, the entire liquid crystal layer is transferred from the splay alignment to the bend alignment using the portion where the twist alignment is formed as a transition nucleus.

  Further, in this liquid crystal display device, as shown in FIGS. 1 and 2, the pixel electrode PE and the scanning line SL2 face each other through a gate insulating film and a dielectric layer made of insulating layers I1 and I2. 4 is configured. That is, in this liquid crystal display device, the scanning line SL2 serves as an auxiliary capacitance line in addition to serving as a gate line.

  The insulating film I2, the pixel electrode PE, and the first transfer electrode TE1 are covered with the alignment film AL1. As the material of the alignment film AL1, for example, a resin such as polyimide can be used. For example, the alignment film AL1 is subjected to an alignment process such as rubbing in the Y direction.

  As shown in FIG. 3, the counter substrate CS includes a transparent substrate SUB2 such as a glass substrate. The substrate SUB2 is disposed so as to face the alignment film AL1.

  A color filter (not shown) and a black matrix BM are arranged on the surface of the substrate SUB2 facing the array substrate AS. The colored layers of the color filter are arranged in a stripe shape, for example. In this liquid crystal display device, the black matrix BM has a lattice shape.

  A counter electrode CE is arranged on the color filter and the black matrix BM. The counter electrode CE is made of a transparent conductor such as ITO, for example. The counter electrode CE is typically a common electrode.

  The counter electrode CE is covered with the alignment film AL2. The alignment film AL2 is separated from a portion of the alignment film AL1 located on the pixel electrode PE and the first transfer electrode TE1 by a spacer (not shown). As the material of the alignment film AL2, for example, a resin such as polyimide can be used. For example, the alignment film AL2 is subjected to an alignment process such as rubbing in the same direction as the alignment film AL1.

  A frame-shaped adhesive layer (not shown) is interposed between the array substrate AS and the counter substrate CS. Further, granular spacers (not shown) are interposed between the array substrate AS and the counter substrate CS and inside the frame on which the adhesive layer is formed. Alternatively, columnar spacers are formed on at least one facing surface of the array substrate AS and the counter substrate CS. These spacers play a role of keeping the thickness of the space surrounded by the array substrate AS, the counter substrate CS, and the adhesive layer constant.

  The liquid crystal layer LC includes a liquid crystal material having positive dielectric anisotropy and refractive index anisotropy. This liquid crystal material forms a bend alignment while displaying an image. Switching between bright display and dark display is performed by changing the absolute value of the voltage applied between the pixel electrode PE and the counter electrode CE, typically a first value greater than zero and a second value greater than the first value. Do this by switching between values. Hereinafter, a state where the absolute value of the applied voltage is the first value is referred to as an OFF state, and a state where the absolute value of the applied voltage is the second value is referred to as an ON state.

  The portion of the counter electrode CE facing the pixel electrode PE, the pixel electrode PE, and the liquid crystal layer LC and the alignment films AL1 and AL2 interposed therebetween constitute the first liquid crystal element LCE1 shown in FIG. . Further, the portion of the counter electrode CE facing the first transition electrode TE1, the first transition electrode TE1, and the liquid crystal layer LC and the alignment films AL1 and AL2 interposed therebetween are shown in FIG. The liquid crystal element LCE2 is configured.

  The switch SW1 and the liquid crystal element LCE1 are connected in series in this order between the signal line VL and the node ND. The switch SW2 and the liquid crystal element LCE2 are connected in series in this order between the signal line VL and the node ND. Note that the node ND is a power supply terminal or a ground terminal connected to the counter electrode CE.

  The optical compensation film OC is, for example, a biaxial film. The optical compensation film OC includes, for example, an optically anisotropic layer in which a uniaxial compound having a negative refractive index anisotropy, such as a discotic liquid crystal compound, is hybrid-aligned.

  For example, the optical axis of the uniaxial compound included in the optical compensation film OC on the substrate SUB1 is substantially parallel to the optical axis in the ON state of the liquid crystal molecules located in the vicinity of the array substrate AS on the substrate SUB1 side, and the opposite side thereof. Then, the liquid crystal molecules positioned in the middle between the array substrate AS and the counter substrate CS are substantially parallel to the optical axis in the ON state. Further, the optical axis of the uniaxial compound included in the optical compensation film OC on the substrate SUB2 is, for example, substantially parallel to the optical axis in the ON state of the liquid crystal molecules located in the vicinity of the counter substrate CS on the substrate SUB2 side. On the opposite side, it is substantially parallel to the optical axis in the ON state of the liquid crystal molecules located in the middle between the array substrate AS and the counter substrate CS. The sum of the retardations of these optical compensation films OC is, for example, substantially equal to the retardation in the ON state of the liquid crystal layer LC.

  For example, the polarizing plates PLZ are arranged so that their transmission axes are substantially orthogonal to each other. Moreover, each polarizing plate PLZ is arrange | positioned so that the transmission axis may make an angle of about 45 degrees with respect to the X direction and the Y direction, for example.

  A backlight (not shown) is arranged to illuminate the array substrate AS of the liquid crystal display panel DP.

  Although the structure in the case where normally white driving is performed by the liquid crystal display panel DP is described here, the liquid crystal display panel DP may be designed to perform normally black driving. In addition, here, a configuration that compensates for the ON state is employed, but a configuration that compensates for the OFF state may be employed.

This liquid crystal display device can be driven by the following method, for example.
FIG. 5 is a timing chart schematically showing an example of a driving method of the liquid crystal display device shown in FIGS.

FIG. 5 shows a waveform of a voltage applied to the wiring or the like when the liquid crystal display device is activated. In the figure, the horizontal axis indicates time, and reference characters V _SL1 and V _SL2 indicate waveforms of voltages applied to the scanning lines SL1 and SL2, respectively. Reference sign V _VL indicates a waveform of a voltage applied to the signal line VL, that is, a waveform of a transition signal output from the X driver to the signal line VL. Reference sign V _CE indicates a waveform of a voltage applied to the counter electrode CE.

  In this liquid crystal display device, the liquid crystal material usually forms a splay alignment in an initial state before power-on. Therefore, when the display device is activated, the following activation process is executed in order to cause a transition from the splay alignment to the bend alignment.

  In the start-up period during which the start-up process is executed (in this example, it is equal to a transfer signal writing period described later), as shown in FIG. 5, all the switches SW1 are kept open. Further, the potential of the counter electrode CE is kept constant during this activation period. Further, in the start-up period, constant voltages having the same magnitude are output as transition signals from the X driver to all signal lines VL. Then, a transfer signal is written to the first transfer electrode TE1 sequentially for each row of the pixels PX.

  Here, as an example, when the switch SW1 is opened, the Y driver outputs a −6V scanning signal to the scanning line SL1, and when the switch SW1 is closed, the Y driver outputs a + 24V scanning signal to the scanning line SL1. I will do it. In addition, the voltage of the counter electrode CE during the startup period is set to −20V. Further, the transition signal output from the X driver to the signal line VL is set to 12.5V.

  When a transition signal is written to the first transition electrode TE1, a potential difference is generated between the first transition electrode TE1 and the pixel electrode PE adjacent in the Y direction. As a result, a transverse electric field that induces a transition from the splay alignment to the twist alignment is generated.

  Subsequent to the activation process, an image display process is executed. An image is displayed by opening all the switches SW2 and using a method similar to that for a general liquid crystal display device.

  In the liquid crystal display devices of FIGS. 1 to 4, for example, when driven by the method of FIG. 5, the wiring load at the initial transition is small. This will be described with reference to FIGS. 1 to 5 and FIGS.

  FIG. 6 is a plan view schematically showing a liquid crystal display device according to a comparative example. FIG. 7 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. In FIG. 6, a part of the liquid crystal display device according to the comparative example is illustrated in an enlarged manner.

  The liquid crystal display device of FIGS. 6 and 7 has the same structure as the liquid crystal display device of FIGS. 1 to 4 except for the following points. That is, in the liquid crystal display devices of FIGS. 6 and 7, the switch SW2 and the transfer electrode TE1 are omitted, and the auxiliary capacitance line CSL is arranged instead of the scanning line SL2. Furthermore, in this liquid crystal display device, the shape of each pixel electrode PE is substantially equal to the shape in which the pixel electrode PE and the transfer electrode TE1 in FIG. 2 are connected.

  FIG. 8 is a timing chart schematically showing an example of a driving method of the liquid crystal display device shown in FIGS.

FIG. 8 shows a waveform of a voltage applied to the wiring or the like when the liquid crystal display device is activated. In the figure, the horizontal axis indicates time, and the reference symbol _VSL1 indicates the waveform of the voltage applied to the scanning line SL1. Reference sign V _VL indicates a waveform of a voltage applied to the signal line VL, that is, a waveform of a transition signal output from the X driver to the signal line VL. Reference sign V _CE indicates a waveform of a voltage applied to the counter electrode CE. Reference sign V _CSL indicates a waveform of a voltage applied to the storage capacitor line CSL.

  In the driving method of FIG. 8, the potentials of the counter electrode CE and the auxiliary capacitance line CSL are kept constant during the startup period. In the start-up period, the transition signal output from the X driver to each signal line VL is switched between the first transition signal and the second transition signal every horizontal period. Then, the transfer signal is written to the pixel electrode PE sequentially for each row of the pixels PX.

  Here, as an example, when the switch SW1 is opened, the Y driver outputs a −6V scanning signal to the scanning line SL1, and when the switch SW1 is closed, the Y driver outputs a + 24V scanning signal to the scanning line SL1. I will do it. In addition, the voltage of the counter electrode CE during the start-up period is set to + 6.5V, and the voltage of the auxiliary capacitance line CSL is set to 0V. Further, the first and second transition signals output from the X driver to the signal line VL are set to 0V and + 12.5V, respectively.

  For example, when the first transition signal is written to the odd-numbered pixel electrode PE and the second transition signal is written to the even-numbered pixel electrode PE, a potential difference is generated between the pixel electrodes PE adjacent in the Y direction. As a result, a transverse electric field that induces a transition from the splay alignment to the twist alignment is generated.

  Subsequent to the activation process, an image display process is executed. An image is displayed by the same method as that of a general liquid crystal display device.

  Thus, when the liquid crystal display device of FIGS. 6 and 7 is driven by the method of FIG. 8, a potential difference is generated between the pixel electrodes PE adjacent in the Y direction to induce a transition from the splay alignment to the twist alignment. Generate a transverse electric field. That is, in the liquid crystal display device of FIGS. 6 and 7, it is necessary to charge the pixel electrode PE having a large area in order to generate a lateral electric field having a certain strength.

  Therefore, in the liquid crystal display devices of FIGS. 6 and 7, when the selection period of each row is relatively short, a large current must be passed through the signal line VL and the switch SW1. Therefore, in this liquid crystal display device, the switch SW1 having a large channel width must be used, and the wiring load on the signal line VL and the scanning line SL1 is large.

  On the other hand, when the liquid crystal display device shown in FIGS. 1 to 4 is driven by the method shown in FIG. 5, a potential difference is generated between the pixel electrode PE adjacent to the Y direction and the first transfer electrode TE1, thereby splay alignment. A transverse electric field that induces a transition from to twisted orientation is generated. That is, in this liquid crystal display device, a horizontal electric field having the same strength can be generated by charging the transfer electrode TE1 having a relatively small area.

  Therefore, in the liquid crystal display devices of FIGS. 1 to 4, even when the selection period of each row is relatively short, it is not necessary to flow a large current through the signal line VL and the switch SW2. Therefore, in this liquid crystal display device, the channel width of the switch SW1 can be reduced, and the wiring load of the signal line VL and the scanning line SL2 can be reduced.

Although the example in which the liquid crystal display device of FIGS. 1 to 4 is driven by the method of FIG. 5 has been described above, the liquid crystal display device can also be driven by other methods.
FIG. 9 is a timing chart schematically showing another example of the driving method of the liquid crystal display device shown in FIGS.

FIG. 9 shows a waveform of a voltage applied to the wiring or the like when the liquid crystal display device is activated. In the figure, the horizontal axis indicates time, and reference characters V _SL1 and V _SL2 indicate waveforms of voltages applied to the scanning lines SL1 and SL2, respectively. Reference sign V _VL indicates a waveform of a voltage applied to the signal line VL, that is, a waveform of a transition signal output from the X driver to the signal line VL. Reference sign V _CE indicates a waveform of a voltage applied to the counter electrode CE.

  In this driving method, the activation period is divided into a reset signal writing period and a transition signal writing period.

  In the reset signal writing period, the voltages of all the signal lines VL are set to the reset voltage. For example, the voltage of all the signal lines VL is made equal to the voltage of the counter electrode CE. In the reset signal writing period, all the switches SW2 are kept open. Then, a reset signal is written to the pixel electrodes PE of all the pixels PX. By this reset process, the potentials of all the pixel electrodes PE are made equal to each other.

  In the transition signal writing period subsequent to the reset signal writing period, for example, the transition signal is written to the first transition electrode TE1 by the method described with reference to FIG. This generates a transverse electric field that induces a transition from the splay alignment to the twist alignment.

  After the above startup process is completed, the image display process is subsequently executed. An image is displayed by opening all the switches SW2 and using a method similar to that for a general liquid crystal display device.

  In the driving method of FIG. 9, prior to writing the transfer signal to the first transfer electrode TE1, the potentials of all the pixel electrodes PE are equalized by a reset process. Therefore, it is possible to prevent the lateral electric field strength from varying due to variations in the potential of the pixel electrode PE. Therefore, when the driving method of FIG. 9 is adopted, the in-plane uniformity of transition is improved as compared with the case where the driving method of FIG. 5 is adopted.

The liquid crystal display device shown in FIGS. 1 to 4 can be driven by another method.
FIG. 10 is a timing chart schematically showing still another example of the driving method of the liquid crystal display device shown in FIGS.

FIG. 10 shows a waveform of a voltage applied to the wiring or the like when the liquid crystal display device is activated. In the figure, the horizontal axis indicates time, and reference characters V _SL1 and V _SL2 indicate waveforms of voltages applied to the scanning lines SL1 and SL2, respectively. Reference sign V _VL indicates a waveform of a voltage applied to the signal line VL, that is, a waveform of a transition signal output from the X driver to the signal line VL. Reference sign V _CE indicates a waveform of a voltage applied to the counter electrode CE.

  In this driving method, the activation period is divided into a first transition signal writing period and a second transition signal writing period.

  In the first transition signal writing period, the voltage applied to the counter electrode CE is set to a constant voltage lower than the voltage of the pixel electrode PE and the transition signal, for example. Here, as an example, the voltage applied to the counter electrode CE in the first transition signal writing period is set to −20V. In the first transition signal writing period, other than this, the transition signal is written to the first transition electrode TE1 by the same method as described with reference to FIG.

  In the second transition signal writing period, the voltage applied to the counter electrode CE is set to a constant voltage higher than the voltage of the pixel electrode PE and the transition signal, for example. Here, as an example, the voltage applied to the counter electrode CE in the second transition signal writing period is set to + 30V. In the second transition signal writing period, other than this, the transition signal is written to the first transition electrode TE1 by the same method as described with reference to FIG.

  After the above startup process is completed, the image display process is subsequently executed. An image is displayed by the same method as a general liquid crystal display device by opening all the switches SW2 and setting the voltage applied to the counter electrode CE to, for example, 6.5V.

  In the driving method of FIG. 10, the transfer signal is written to each first transfer electrode TE1 in each of the first transfer signal writing period and the second transfer signal writing period. In addition, in the method of FIG. 10, the polarity of the voltage applied between the pixel electrode PE and the first transition electrode TE1 and the counter electrode CE is changed between the first transition signal writing period and the second transition signal writing period. Reverse. This makes it possible to cause the transition from the splay alignment to the bend alignment in a shorter time compared to the case where the driving method of FIG. 5 is adopted.

  Various modifications can be made to the driving method described above. For example, the driving method of FIG. 9 and the driving method of FIG. 10 may be combined. That is, the activation period is divided into a reset signal writing period, a first transition signal writing period, and a second transition signal writing period, and the reset signal writing described with reference to FIG. 9 and FIG. The transfer signal writing described above may be sequentially performed. In this case, the effect described with reference to FIGS. 9 and 10 can be obtained.

Next, the second aspect of the present invention will be described.
FIG. 11 is a plan view schematically showing a liquid crystal display device according to the second embodiment of the present invention. 12 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. In FIG. 11, a part of the liquid crystal display device according to the second embodiment is illustrated in an enlarged manner.

  The liquid crystal display device of FIGS. 11 and 12 has the same structure as the liquid crystal display device of FIGS. 1 to 4 except for the following points. That is, in the liquid crystal display devices of FIGS. 11 and 12, the switch SW2 is omitted, and the auxiliary capacitance line CSL is disposed instead of the scanning line SL2. Further, in this liquid crystal display device, the first transition electrode TE1 is directly connected to the storage capacitor line CSL.

This liquid crystal display device is driven by, for example, the following method.
In the start-up period, the voltage of the signal line VL is maintained at a constant value, for example, 0V. Here, as an example, the voltage of the counter electrode CE is also maintained at a constant value. In this period, all the switches SW1 are kept open by setting the voltage of the scanning line SL1 to, for example, −6V. Then, for example, the transfer signal described with reference to FIG. 5 is output from the Y driver to the auxiliary capacitance line CSL.

  Thus, a potential difference is generated between the first transition electrode TE1 and the pixel electrode PE adjacent in the Y direction. That is, a transverse electric field that induces a transition from the splay alignment to the twist alignment is generated.

  Subsequent to the activation process, an image display process is executed. An image is displayed by the same method as that of a general liquid crystal display device. However, the voltages of all the auxiliary capacitance lines CSL are made equal to each other. For example, the voltage of the storage capacitor line CSL is made equal to the voltage of the counter electrode CE.

  In this driving method, no current flows through the switch in the pixel PX during the start-up period. In addition, this liquid crystal display device induces a transition from the splay alignment to the bend alignment by using the first transition electrode TE1 as in the liquid crystal display devices of FIGS. Therefore, also in this aspect, similarly to the first aspect, the channel width of the switch SW1 can be reduced, and the wiring loads of the signal line VL and the scanning line SL2 can be reduced.

  Further, in this liquid crystal display device, unlike the liquid crystal display devices of FIGS. 1 to 4, the switch SW2 is not disposed in the pixel PX. That is, according to this aspect, the structure of the liquid crystal display device can be simplified as compared with the first aspect.

Next, the third aspect of the present invention will be described.
FIG. 13 is a plan view schematically showing a liquid crystal display device according to the third aspect of the present invention. FIG. 14 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. In FIG. 13, a part of the liquid crystal display device according to the third embodiment is illustrated in an enlarged manner.

  The liquid crystal display device of FIGS. 13 and 14 has the same structure as the liquid crystal display device of FIGS. 1 to 4 except for the following points.

  That is, in this liquid crystal display device, the dimension of the pixel electrode PE in the Y direction is made smaller than that of the liquid crystal display device of FIGS. 1 to 4, and the side of the pixel electrode PE on the first transition electrode TE1 side is linear. I have to. Further, in this liquid crystal display device, the second transition electrode TE2 having a shape substantially equal to the first transition electrode TE1 is provided between the pixel electrode PE and the first transition electrode TE1, and the wave-shaped sides thereof are arranged. It is arranged to face each other. The portion of the counter electrode CE facing the second transition electrode TE2, the second transition electrode TE2, and the liquid crystal layer LC and the alignment films AL1 and AL2 interposed therebetween are the third liquid crystal element shown in FIG. LCE3 is configured.

  In the liquid crystal display device of FIGS. 13 and 14, a switch SW3 is further provided for each pixel PX. Here, as an example, an n-channel thin film transistor is used for the switch SW3. In each pixel PX, the switch SW3 is connected between the second transition electrode TE2 included in the pixel PX and the signal line VL connected to the pixel PX and the switch SW2 included in the pixel PX adjacent in the X direction. ing. In each pixel PX, the gate of the switch SW2 and the gate of the switch SW3 are connected to the same scanning line SL2.

This liquid crystal display device is driven by, for example, the following method.
In the startup period, the first voltage is output as the first transition signal from the X driver to the odd-numbered signal lines VL. In the driving period, the X driver outputs a second voltage different from the first voltage as the second transition signal to the signal line VL in the even-numbered column. Further, during this period, all the switches SW1 are kept open. Here, as an example, the X driver outputs a first transition signal of 0 V to the odd-numbered signal lines VL, and outputs a second transition signal of +12.5 V to the even-numbered signal lines VL. .

  Then, the first and second transition signals are written to the first transition electrode TE1 and the second transition electrode TE2, respectively, for each row of the pixels PX. Thereby, a potential difference is generated between the first transition electrode TE1 and the second transition electrode TE2 adjacent in the Y direction. That is, a transverse electric field that induces a transition from the splay alignment to the twist alignment is generated.

  Subsequent to the activation process, an image display process is executed. An image is displayed by opening all the switches SW2 and SW3 and using a method similar to that of a general liquid crystal display device.

  In this driving method, the transition from the splay alignment to the bend alignment is induced by using the transfer electrodes TE1 and TE2 having a smaller area than the pixel electrode PE. Therefore, in this aspect, the channel widths of the switches SW2 and SW3 can be reduced, and the wiring loads of the signal line VL and the scanning line SL2 can be reduced.

  In the first mode, a transfer signal is supplied only to the first transfer electrode TE1 to generate a potential difference between the first transfer electrode TE1 and the pixel electrode PE, and a horizontal electric field generated thereby is used to perform spraying. A transition from orientation to twist orientation was induced. On the other hand, in this embodiment, as described above, a transition signal is supplied to both the first transition electrode TE1 and the second transition electrode TE2 to generate a potential difference between the transition electrodes TE1 and TE2. The transition from the splay alignment to the twist alignment is induced using the lateral electric field generated by the above. Therefore, according to this aspect, compared with the first aspect, a stronger lateral electric field can be generated, and the time required for the transition from the splay alignment to the twist alignment can be shortened.

Next, the fourth aspect of the present invention will be described.
FIG. 15 is a plan view schematically showing a liquid crystal display device according to the fourth aspect of the present invention. FIG. 16 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. In FIG. 15, a part of the liquid crystal display device according to the fourth aspect is illustrated in an enlarged manner.

  The liquid crystal display device of FIGS. 15 and 16 has the same structure as the liquid crystal display device of FIGS. 1 to 4 except for the following points.

  That is, in this liquid crystal display device, the dimension of the pixel electrode PE in the Y direction is made smaller than that of the liquid crystal display device of FIGS. 1 to 4, and the side of the pixel electrode PE on the first transition electrode TE1 side is linear. I have to. Further, in this liquid crystal display device, the second transition electrode TE2 having a shape substantially equal to the first transition electrode TE1 is provided between the pixel electrode PE and the first transition electrode TE1, and the wave-shaped sides thereof are arranged. It is arranged to face each other. The second transition electrode TE2 is connected to the scanning line SL2. The portion of the counter electrode CE facing the second transition electrode TE2, the second transition electrode TE2, and the liquid crystal layer LC and the alignment films AL1 and AL2 interposed therebetween are the third liquid crystal element shown in FIG. LCE3 is configured.

This liquid crystal display device is driven by, for example, the following method.
In the start-up period, the first voltage is output from the X driver to each signal line VL as the first transition signal. The first voltage is a voltage different from the scanning signal for closing the switch SW2, and is set to 0 V as an example here. During this period, all the switches SW1 are kept open. Then, the writing of the first transition signal to the first transition electrode TE1 is sequentially performed for each row of the pixels PX.

  As described above, the second transition electrode TE2 is connected to the scanning line SL2. Therefore, when writing the first transition signal to the first transition electrode TE1 included in a certain pixel PX, the second transition electrode TE2 included in the pixel PX has a scanning signal for closing the switch SW2, for example, a second voltage of + 24V. , Are written as the second transition signal. As a result, a potential difference is generated between the first transition electrode TE1 and the second transition electrode TE2 adjacent in the Y direction, and a lateral electric field that induces transition from the splay alignment to the twist alignment is generated.

  Subsequent to the activation process, an image display process is executed. An image is displayed by opening all the switches SW2 and using a method similar to that for a general liquid crystal display device.

  In this aspect, the transition from the splay alignment to the bend alignment is induced using the transfer electrodes TE1 and TE2 having a smaller area than the pixel electrode PE. Further, in this embodiment, as described above, a transfer signal is supplied to both the first transfer electrode TE1 and the second transfer electrode TE2 to generate a potential difference between the transfer electrodes TE1 and TE2, and thereby generated. A transition from the splay alignment to the twist alignment is induced using a lateral electric field. Therefore, according to this aspect, the same effect as described in the third aspect can be obtained.

  Further, in this aspect, unlike the third aspect, the switch SW3 is not disposed in the pixel PX. That is, according to this aspect, the structure of the liquid crystal display device can be simplified as compared with the third aspect.

  In the first and second modes, one side of the first transition electrode TE1 and one side of the pixel electrode PE are waveforms, but only one of them may be a waveform. Similarly, in the third and fourth aspects, one side of the first transition electrode TE1 and one side of the second transition electrode TE2 have waveforms, but only one of them may have a waveform.

  In the first to fourth aspects, the signal line VL, the scanning line SL2, or the storage capacitor line CSL is used for supplying the transition signal to the pixel PX. However, in order to supply the transition signal to the pixel PX separately from these wirings. The wiring may be provided. For example, in the first mode, a signal line for supplying a transition signal to the first transition electrode TE1 may be provided separately from the signal line VL for supplying a video signal to the pixel electrode PE. In the second mode, a wiring for supplying a transition signal to the first transition electrode TE1 may be provided separately from the storage capacitor line CSL. In the third mode, wirings for supplying the first and second transition signals to the transition electrodes TE1 and TE2 may be provided separately from the signal line VL. In the fourth aspect, wirings for supplying the first and second transition signals to the transition electrodes TE1 and TE2 may be provided separately from the signal line VL and the scanning line SL2.

  In the first to fourth aspects, the switch SW1 is kept open in the transition signal writing period, but the switch SW1 may be closed in the transition signal writing period as appropriate. For example, in the first aspect, when a wiring for supplying a transition signal to the pixel PX is provided independently from the signal line VL, a signal different from the transition signal is output to the previous wiring in the transition signal writing period. For example, the switch SW1 may be closed. In the second mode, the switch SW1 may be closed if a signal different from the transition signal is output to the signal line VL in the transition signal writing period. In the third and fourth aspects, when the wiring for supplying the first and second transition signals to the pixel PX is provided independently from the signal line VL, the first and second signal lines VL are provided with the first and second signals in the transition signal writing period. If a signal different from the second transition signal is output, the switch SW1 may be closed.

1 is a plan view schematically showing a liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is an enlarged plan view showing a part of the liquid crystal display device shown in FIG. 1. Sectional drawing along the III-III line of the liquid crystal display device shown in FIG. FIG. 2 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. 1. 5 is a timing chart schematically showing an example of a driving method of the liquid crystal display device shown in FIGS. The top view which shows schematically the liquid crystal display device which concerns on a comparative example. FIG. 7 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. 6. 8 is a timing chart schematically showing an example of a method for driving the liquid crystal display device shown in FIGS. 5 is a timing chart schematically showing another example of a method for driving the liquid crystal display device shown in FIGS. 5 is a timing chart schematically showing still another example of the driving method of the liquid crystal display device shown in FIGS. The top view which shows schematically the liquid crystal display device which concerns on the 2nd aspect of this invention. FIG. 12 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. 11. The top view which shows schematically the liquid crystal display device which concerns on the 3rd aspect of this invention. FIG. 14 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. 13. The top view which shows schematically the liquid crystal display device which concerns on the 4th aspect of this invention. FIG. 16 is an equivalent circuit diagram of the liquid crystal display device shown in FIG. 15.

Explanation of symbols

  AL1 ... alignment film, AL2 ... alignment film, AS ... array substrate, BM ... black matrix, C ... capacitor, CE ... counter electrode, CS ... counter substrate, CSL ... auxiliary capacitance line, DE ... drain electrode, DP ... liquid crystal display panel , I1 ... insulating film, I2 ... insulating film, LC ... liquid crystal layer, LCE1 ... liquid crystal element, LCE2 ... liquid crystal element, LCE3 ... liquid crystal element, ND ... node, OC ... optical compensation film, PE ... pixel electrode, PLZ ... polarizing plate , SC ... semiconductor layer, SL1 ... scan line, SL2 ... scan line, SUB1 ... transparent substrate, SUB2 ... transparent substrate, SW1 ... switch, SW2 ... switch, SW3 ... switch, TE1 ... transition electrode, TE2 ... transition electrode, VL: Signal line.

Claims (8)

An array substrate including a plurality of pixel circuits each including a pixel electrode and a first transition electrode;
A counter substrate having a counter electrode facing the plurality of pixel circuits;
Comprising a liquid crystal layer interposed between the array substrate and the counter substrate;
Each of the plurality of pixel circuits further includes a first switch that switches a supply state of the video signal to the pixel electrode, and a second switch that switches a supply state of the transition signal to the first transition electrode,
The array substrate further includes a plurality of first and second scanning lines alternately arranged and a plurality of signal lines intersecting with the first and second scanning lines.
In each of the plurality of pixel circuits, the first switch is connected between the signal line and the pixel electrode, and the second switch is connected to the same signal line as the first switch is connected to the pixel electrode. A liquid crystal display device, wherein the liquid crystal display device is connected to a first transition electrode, and the switching operations of the first and second switches are controlled by scanning signals respectively supplied from the first and second scanning lines. .   2. The liquid crystal display device according to claim 1, wherein the second scanning line is a storage capacitor line facing the pixel electrode with a dielectric layer interposed therebetween.   2. The liquid crystal display device according to claim 1, wherein each of the plurality of pixel circuits further includes a second transition electrode adjacent to the first transition electrode. Each of the plurality of pixel circuits includes a first switch that switches a supply state of the video signal to the pixel electrode, a second switch that switches a supply state of the first transition signal to the first transition electrode, and the first switch. The liquid crystal display device according to claim 3 , further comprising a third switch that switches a supply state of the second transition signal to the second transition electrode. The array substrate further includes a plurality of first and second scanning lines alternately arranged and a plurality of signal lines intersecting with the first and second scanning lines.
In each of the plurality of pixel circuits, the first switch is connected between the signal line and the pixel electrode, and the second switch is connected to the same signal line as the first switch is connected to the pixel electrode. The third switch is connected between the first transfer electrode, the third switch is connected between the signal line different from the first switch, and the second switch electrode. The switching operation is controlled by a scanning signal supplied from the first scanning line, and the switching operations of the second and third switches are controlled by a scanning signal supplied from the same second scanning line. The liquid crystal display device according to claim 4 . Each of the plurality of pixel circuits further includes a first switch that switches a supply state of the video signal to the pixel electrode, and a second switch that switches a supply state of the transition signal to the first transition electrode,
The array substrate further includes a plurality of first and second scanning lines alternately arranged and a plurality of signal lines intersecting with the first and second scanning lines.
In each of the plurality of pixel circuits, the first switch is connected between the signal line and the pixel electrode, and the second switch is connected to the same signal line as the first switch is connected to the pixel electrode. The switching operation of the first and second switches is controlled by scanning signals supplied from the first and second scanning lines, respectively, and the second transition electrode is connected to the first transition electrode. 6. The liquid crystal display device according to claim 5 , wherein the liquid crystal display device is connected to the second scanning line for controlling the switching operation of the two switches.   The transition from a splay alignment to a bend alignment of a liquid crystal material included in the liquid crystal layer is induced by writing a transition signal to the transition electrode when the liquid crystal display device is activated. Liquid crystal display device. A method for driving a liquid crystal display device according to claim 1,
A driving method characterized by inducing a transition from a splay alignment to a bend alignment of a liquid crystal material included in the liquid crystal layer by writing a transition signal to the transition electrode when the liquid crystal display device is activated.

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