JP2004094265A - Method for driving liquid crystal display element, liquid crystal display and reflective field-sequential projector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for driving a liquid crystal display element which ensures high contrast and high luminance and is uninfluenced by electrical asymmetry without using a reset pulse or performing a arithmetic operation between image data. <P>SOLUTION: In the first driving method, one frame consists of a first field and a second field, data are written two or more times in the first field at a prescribed signal voltage, and then the sign of the signal voltage is reversed and data are written two or more times in the second field. In the second driving method, data are written two or more times in one frame at a signal voltage whose polarity is alternately reversed positive and negative with a prescribed period. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for driving a liquid crystal display device and a liquid crystal display device, and more particularly, to a method for driving a liquid crystal display device with high contrast and high brightness and without influence of electrical asymmetry, and a liquid crystal display device. Relates to a liquid crystal display device driven by such a driving method.

At present, the mainstream of high-performance liquid crystal displays is a TFT (thin film transistor) type active matrix liquid crystal display device of a TN (twisted nematic) mode or an IPS (in-plane switching) mode using a nematic liquid crystal. In these active matrix liquid crystal display devices, an image signal is normally rewritten at 60 Hz to write positive and negative at 30 Hz, and the time of one field is about 16.7 ms (millisecond) (both positive and negative fields). Is called one frame and is about 33.3 ms). On the other hand, the response speed of the liquid crystal is the frame time, that is, about 33.3 ms at present even at the fastest. Therefore, when displaying a video signal composed of a moving image or displaying a high-speed computer image, a liquid crystal response speed faster than the current frame time is required.

フ ィ ー ル ド By the way, in order to achieve higher definition, a field-sequential color liquid crystal display device that switches the backlight, which is the illumination light of the liquid crystal display device, in time from red, green, and blue is also being studied. In this method, there is no need to spatially dispose the color filters, so that it is possible to achieve three times higher definition than in the past. In a field sequential color liquid crystal display device, one color needs to be displayed in 1/3 of one field, so that the time available for display is about 5 ms. Therefore, the liquid crystal itself is required to respond faster than 5 ms. As a liquid crystal capable of realizing such a high-speed response, a liquid crystal having spontaneous polarization such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal is being studied. Further, in the case of nematic liquid crystals, studies have been made to increase the speed by increasing the dielectric anisotropy, decreasing the viscosity, reducing the film thickness, or changing the liquid crystal alignment to a pi-type alignment.

On the other hand, in the active matrix liquid crystal display element, the time during which the voltage and the electric charge are actually written to the liquid crystal portion is only the selection time (writing time) of each scanning line. This time is 16.7 μs (microsecond) when writing is performed in one field time with 1000 lines, and about 5 μs when performing field sequential driving. At present, there is almost no liquid crystal or liquid crystal use mode in which the response is completed within this time. As for the liquid crystal having the above-mentioned spontaneous polarization or the nematic liquid crystal having a high speed, an element which has such a fast response is not known.

As a result, the following problem occurs because the liquid crystal responds after the completion of signal writing. First, in a liquid crystal having spontaneous polarization, an anti-electric field is generated due to the rotation of spontaneous polarization, and the voltage across the liquid crystal layer rapidly decreases. For this reason, the voltage written across the liquid crystal layer changes greatly. In addition, even in a high-speed nematic liquid crystal, the change in capacitance of the liquid crystal layer due to dielectric anisotropy becomes extremely large, so that a change occurs in a holding voltage to be written and held in the liquid crystal layer. Such a decrease in the holding voltage, that is, a decrease in the effective applied voltage causes insufficient writing and lowers the contrast. Further, when the same signal is continuously written, the luminance continues to change until the holding voltage does not decrease, and it takes several frames to obtain stable luminance.

Further, as shown in Non-Patent Document 1, when the image signal changes and the same image signal is continuously written over several frames from the frame in which the absolute value of the signal voltage has changed, a “step response” is generated. A phenomenon called is seen. This phenomenon is a phenomenon in which the transmittance vibrates brightly and darkly over several frames with respect to the AC drive signal voltage having the same amplitude, and thereafter becomes stable to a constant transmitted light amount. An example of this phenomenon is shown in the schematic diagram of FIG. 12A is a waveform diagram of the data voltage, FIG. 12B is a waveform diagram of the gate voltage, and FIG. 12C is a waveform diagram of the transmittance at that time.

FIG. 13 is a timing chart for each scanning line in the drive shown in FIG. 12, and the shading of the positive and negative display periods 102 and 104 represents the luminance based on the transmittance of FIG. In FIG. 13, the time of 16.7 ms is indicated by an arrow. In FIG. 13, six scanning lines are assumed, positive writing 101 is performed sequentially from the upper scanning line, a positive display 102 is obtained, and then negative writing 103 is sequentially performed again from the upper scanning line. Is performed to obtain a negative display 104. For each scanning line, a period obtained by adding a period of positive writing 101 and a period of a positive display 102 is a first field, and a period obtained by adding a period of negative writing 103 and a period of a negative display 104 is a second field. The total of the fields is one frame. When the data voltage shown in FIG. 12A is applied and the TFT switch is turned on with the gate voltage shown in FIG. 12B, the transmittance vibrates brightly and darkly for each field as shown in FIG. 12C. Such transmittance vibration is observed as flicker, and causes deterioration of display quality. In addition, as shown in FIG. 12C, after applying the signal voltage, the transmittance is settled at a constant transmittance in the second frame (four fields). As a result, the luminance change also oscillates as shown in FIG. As described above, even when the high-speed response liquid crystal is used, several frames are required to stabilize the actual luminance, and the high-speed display image is lost.

On the other hand, the transmittance after the liquid crystal response is determined not by the applied signal voltage but by the charge amount stored in the liquid crystal capacitance after the liquid crystal response. This charge amount is determined by the accumulated charge before the predetermined signal writing and the newly written charge. The accumulated charge after this response also changes depending on the pixel design values such as the physical constants of the liquid crystal, the electrical parameters, and the storage capacitance. For this reason, the correspondence between the signal voltage and the transmittance is obtained by (1) the correspondence between the signal voltage and the write charge, (2) the accumulated charge before the write, and (3) the information for calculating the accumulated charge after the response. And actual calculation processing and the like are required. As a result, a frame memory for storing (2) over the entire screen and a calculation unit of (1) or (3) are required. This results in an increase in the number of parts of the system, which is not preferable.

As a method for solving these problems, a reset pulse method of applying a reset voltage to make a predetermined liquid crystal state before writing new data is often used. As an example, a technique described in Non-Patent Document 2 will be described. In this document, an OCB (optically compensated birefrigence) mode in which a nematic liquid crystal is oriented in a pie shape and a compensation film is added is used. The response speed of this liquid crystal mode is about 2 to 5 milliseconds, which is much faster than the conventional TN mode. Originally, the response should end within one frame. However, as described above, a change in the dielectric constant due to the response of the liquid crystal causes a large decrease in the holding voltage, and several frames are required until a stable transmittance is obtained. Therefore, in the above-mentioned document, a method of always writing black display after writing white display in one frame is shown in FIG. 5 of the document. This figure is referred to as FIG. The horizontal axis is time, and the vertical axis is luminance. The dotted line indicates a change in luminance in the case of normal driving, and reaches a stable luminance in the third frame. On the other hand, according to the reset pulse method, the new data is always in a predetermined state at the time of writing, so that a one-to-one correspondence of a constant transmittance to a constant signal voltage written is seen. This one-to-one correspondence greatly simplifies the mechanism for generating the driving signal and eliminates the need for a means such as a frame memory for storing the previous write information.

As another means for solving these problems, a driving method called “pseudo DC driving” disclosed in Non-Patent Document 3 has been proposed. This technique will be described with reference to FIG. 15A and 15B are waveform diagrams of the data voltage, FIG. 15B is a waveform diagram of the gate voltage, and FIG. 15C is a waveform diagram of the transmittance at that time, similarly to FIG. FIG. 16 is a timing chart for each scanning line, and the shading of the positive and negative display periods 102 and 104 represents the luminance based on the transmittance of FIG. In FIG. 15, the time of 16.7 ms is indicated by an arrow. In the description in the literature, 16.7 ms is defined as one frame time. However, since this definition is not general, it is changed in the figures in this specification (one frame time in the literature is not (Corresponds to one field time in the specification with respect to the usual prior art).

In the “pseudo DC driving”, unlike the normal AC driving shown in FIG. 12, a data voltage of the same sign is continuously applied during a plurality of fields. After a plurality of fields, the sign of the data voltage is inverted to eliminate electrical bias. In FIG. 15, after the positive writing of four fields, the negative writing of four fields is performed, and the display of one image signal ends. The timing of writing for each scanning line is as shown in FIG. 16. Writing positive data sequentially from the top, repeating this four times, and then writing negative data sequentially from the top is repeated four times. In this method, a state is obtained in which the applied constant DC voltage is the same as the holding voltage at both ends of the liquid crystal. As a result, the holding voltage does not decrease due to the response of the liquid crystal, and the final transmittance increases as compared with the method in which the holding voltage decreases due to the response of the liquid crystal as in the AC driving in FIG. However, one frame time in this method is the sum of a plurality of frames of each code. That is, in the example of FIG. 15, one frame time of this method takes four times as long as the frame of FIG.
Japanese Applied Physics, Vol. 36, Part 1, Number 2 (pp. 720-729) IRD C 1997 (pages L-66 to L-69) Digest of AMLC 97 (pages 119 to 122)

(4) As described above, the method of comparing the accumulated charges before and after writing requires a comparison operation unit and the like in addition to the frame memory, which causes an increase in the system. Further, in the method using the reset pulse, a reset period for keeping a constant state is required, so that the time for writing and displaying is substantially shortened. In addition, since there is always a period in which the transmittance is constant, flicker is likely to occur. That is, in the reset pulse method, a decrease in contrast occurs due to a decrease or increase in the in-plane distribution of luminance, flicker, and average luminance. On the other hand, the pseudo DC drive requires a longer frame time (four times as long as the AC drive in FIGS. 15 and 16) as compared with the AC drive as described above, and high-speed response cannot be utilized. As a result, a long-period flicker which oscillates at several times the normal frame time (16.7 ms) as shown in FIG. 16 is generated.

Therefore, an object of the present invention is to provide a method of driving a liquid crystal display element in which there is a one-to-one correspondence between an applied signal voltage and transmittance without using a reset pulse method or a frame memory. It is another object of the present invention to provide a method of driving a liquid crystal display element in which a one-to-one correspondence between an applied signal voltage and a transmittance is observed and a high-speed response is possible. Another object of the present invention is to provide a liquid crystal display device using such a driving method.

In order to achieve the above object, a method for driving a liquid crystal display element according to the present invention (hereinafter, referred to as a first driving method) includes a liquid crystal display element having a response speed faster than one frame time, wherein one frame has an odd number. A predetermined gray-scale voltage data is written a plurality of times in an odd-numbered field, and then a plurality of gray-scale voltage data obtained by inverting the voltage order of the gray scales in an even-numbered field is written a plurality of times. .
Further, in the liquid crystal display element having a response speed faster than one frame time, the second driving method of the liquid crystal display element includes a plurality of times in a frame of grayscale voltage data in which a voltage order for grayscale is inverted at a predetermined cycle. It is characterized by writing.
A third driving method of a liquid crystal display device is characterized in that a scanning line group is divided into a plurality of blocks, and the plurality of blocks are scanned simultaneously.
A fourth method of driving a liquid crystal display element is a method of driving a color field sequential liquid crystal display device in which one frame is divided into a plurality of subfields according to a plurality of colors, and data of each color is sequentially displayed in each subfield. The method of driving each color is based on the method of driving a liquid crystal display element described in the third aspect.
The first liquid crystal display device is characterized in that a liquid crystal display element constituting the liquid crystal display device is driven by the method for driving a liquid crystal display element according to any one of the first to third aspects.
A color field sequential liquid crystal display device in which information of a plurality of colors is sequentially displayed in one frame, wherein the color field sequential liquid crystal display device is driven by the method for driving a liquid crystal display device according to the fourth aspect. Device.

According to the present invention, in a high-speed response liquid crystal display device, without using a reset pulse, without performing an operation between image data, high contrast and high brightness, without the influence of electrical asymmetry, A method for driving a liquid crystal display element can be realized. According to the present invention, a liquid crystal display device and a field sequential liquid crystal display device using those driving methods can be realized.

Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the accompanying drawings.
Embodiment 1
This embodiment is an example of an embodiment of a first driving method of a liquid crystal display element according to the present invention. FIG. 1A is a waveform diagram of a voltage applied to a data line, and FIG. 1B is a gate line. FIG. 1C is a diagram showing a change in transmittance when the voltages shown in FIGS. 1A and 1B are applied to a liquid crystal which responds at high speed. On the one hand, this embodiment corresponds to an increase in the frequency of the pseudo DC drive method, and from another point of view, it corresponds to writing a plurality of times in one field by AC drive. Specifically, the voltage applied to the data line in FIG. 1A is a rectangular wave constituting one frame in two fields of 16.7 ms per field, which is the same as the AC drive in FIG. On the other hand, the voltage applied to the gate line in FIG. 1B has a plurality of (in this case, four) ON pulses during one field period. As a result, as shown in FIG. 1C, the transmittance gradually increases according to the number of times of writing during 16.7 ms in one field, and reaches a stable state by the fourth writing.

FIG. 2 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line in the first driving method. The case where there are six scanning lines is shown, and the display luminance is shown by shading. As shown in FIG. 2, the first field is formed by repeating scanning from the top sequentially and performing positive writing four times. Thereafter, inversion of the data signal voltage, sequential scanning from the top and negative writing are repeated four times, and the second field is completed. One frame is formed by the first field and the second field. The time of the first field is 16.7 ms. As shown in FIG. 1C, the luminance increases as the number of times of writing increases in the same field. In addition, the writing time of each scanning line is 1 / n of the writing time of the normal driving method when writing is performed n times in one field.

Embodiment 2
This embodiment is another example of the embodiment of the second driving method of the liquid crystal display element according to the present invention. FIG. 3A is a waveform diagram of a voltage applied to a data line, and FIG. FIG. 3 (c) is a waveform diagram of the voltage applied to the gate line, and FIG. 3 (c) is a diagram showing a change in transmittance when the voltages shown in FIGS. The present embodiment corresponds to a case where the frequency of AC driving is increased. Specifically, the voltage applied to the data line in FIG. 3A is a rectangular wave having a frequency several times (in this case, twice) that of FIG. On the other hand, the voltage applied to the gate line in FIG. 3B has one ON pulse during one field period, and each field is given for each voltage code in FIG. As a result, in FIG. 3, there are four fields in one frame. In the present embodiment, as shown in FIG. 3C, the step response is generated in response to the write signal within the period of 16.7 ms, the oscillation width is gradually suppressed, and the fourth oscillation is performed. A stable state is reached by writing.

FIG. 4 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line. The case where there are six scanning lines is shown, and the display luminance is shown by shading. As shown in FIG. 4, the first field is formed by sequentially scanning from the top and performing positive writing, and thereafter, the data signal voltage is inverted, and the second field is formed by sequentially scanning from the top and performing negative writing. Is done. Further, a third field is formed by sequentially scanning from the top and performing positive writing, and thereafter, a data signal voltage is inverted, and a fourth field is formed by sequentially scanning from the top and performing negative writing. One frame is formed by these first to fourth fields. The time of the first field is 8.35 ms. The brightness oscillates within the frame as shown in the transmittance graph of FIG. 3C and stabilizes at the end of the frame. Note that the writing time of each scanning line is 1 / n of the writing time of the normal AC driving method when the AC driving is performed n times in one frame.

Embodiment 3
This embodiment is an example of an embodiment of the third driving method of the liquid crystal display element according to the present invention. FIG. 5 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line. In this embodiment, as in the first embodiment, the same data signal is written a plurality of times in one field. The difference from the first embodiment is the scanning method. In the present embodiment, a plurality of scanning lines are simultaneously scanned. As shown in FIG. 5, the scanning line group is divided into an upper block and a lower block, and one line of each of the upper block and the lower block is selected and scanned sequentially from top to bottom. As a result, it is possible to secure twice the time required for writing the individual scanning lines as in the first embodiment. In addition, the writing time of each scanning line is m / n of the writing time of the normal AC driving method when writing is performed n times in one field and divided into m scanning line blocks.

Embodiment 4
The present embodiment is an example of an embodiment of a fourth driving method of the liquid crystal display element according to the present invention, and FIG. 6 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line. In the present embodiment, similar to the second embodiment, the AC drive is performed a plurality of times in one frame. The difference from the second embodiment lies in the scanning method. In the present embodiment, a plurality of scanning lines are simultaneously scanned. As shown in FIG. 6, the scanning line group is divided into an upper block and a lower block, and one line of each of the upper block and the lower block is selected and scanned sequentially from top to bottom. As a result, it is possible to secure twice the time required for writing the individual scanning lines in the second embodiment. Note that the writing time of each scanning line is m / n of the writing time in the normal AC driving method when AC driving is performed n times in one frame and divided into m scanning line blocks.

Embodiment 5
This embodiment is an example of an embodiment of the fifth driving method of the liquid crystal display element according to the present invention. FIG. 7 is a time chart showing the configuration and operation of the time distribution of the luminance of the light source and the time distribution of each scanning line. FIG. 6 is a diagram illustrating display luminance for each scanning line. In the present embodiment, as in the first embodiment, the same data signal is written a plurality of times in one field, and scanning similar to that in the third embodiment is performed. The difference from the first and third embodiments is that the field sequential drive is used, and each field has a fixed display period 105. FIG. 7 shows an example using 12 scanning lines.

# 1 frame is divided into three fields corresponding to each color, and AC driving is performed in each field. Also, writing is performed a plurality of times within each polarity of the AC drive. On the other hand, a scanning line is also divided into a plurality of blocks, and writing is performed simultaneously. As shown in FIG. 7, the scanning line is divided into four blocks, and the top scanning line of each block is simultaneously selected and written, and sequentially written from top to bottom. The scanning is repeated four times to continue writing one polarity (positive in this case) of the AC drive. Thereafter, a display period 105 is given. The polarity of the signal data is inverted, and the scanning of four blocks is repeated four times in the same manner. Thus, the negative writing 103 is completed and the display period 105 is given. At this time, the light source is turned on in a range including the display period, and is turned off in a range where the transmittance is unstable. By this procedure, the first field is formed, and the display in red is completed. Similarly, green, blue and blue fields are displayed, and one frame is formed by three fields.

Embodiment 6
This embodiment is an example of an embodiment of a sixth driving method of the liquid crystal display element according to the present invention. FIG. 8 is a time chart showing the configuration and operation of the time distribution of the luminance of the light source and the time distribution of each scanning line. FIG. 6 is a diagram illustrating display luminance for each scanning line. In the present embodiment, similar to the second embodiment, the AC driving is performed a plurality of times within one field, and the same scanning as the fourth embodiment is performed. The difference from the second and fourth embodiments is that the field sequential drive is used, and a fixed display period 105 is provided in each field. FIG. 8 shows an example using 12 scanning lines. One frame is divided into three fields corresponding to each color, and AC driving is performed in each field. The AC driving is performed a plurality of times. On the other hand, a scanning line is also divided into a plurality of blocks, and writing is performed simultaneously. As shown in FIG. 8, the scanning line is divided into four blocks, and the top scanning line of each block is simultaneously selected and written, and sequentially written from top to bottom. The scanning is repeated four times to perform AC driving for two cycles. Thereafter, a display period 105 is given. At this time, the light source is turned on in a range including the display period, and is turned off in a range where the transmittance is unstable. By this procedure, the first field is formed, and the display in red is completed. Similarly, green, blue and blue fields are displayed, and one frame is formed by three fields.

Embodiment 7
The present embodiment is an example of an embodiment of a liquid crystal display device according to the present invention, and is a liquid crystal display device using any of the driving methods of Embodiments 1 to 4. FIG. 9 is a schematic diagram illustrating an example of a configuration of a liquid crystal display device to which the driving method of the present invention is applied. In the liquid crystal display device of the present embodiment, an electrode 7 is formed on each of two support substrates 6, and an alignment film 8 for aligning liquid crystal is formed thereon. The liquid crystal 9 is sandwiched between the pair of support substrates 6, and a pair of polarizing plates is provided outside the support substrate 6. With this configuration, a liquid crystal display device is usually configured. Hereinafter, the operation of this embodiment will be described in detail. A signal data waveform corresponding to each driving method at a predetermined frequency is applied to each drain bus line corresponding to each gate line. On the other hand, the waveform shown in each embodiment is applied to each gate bus line such that the active element is turned on when the line is selected, whereby the waveform of the drain line is applied to the liquid crystal by the display electrode. . The voltage is held in the liquid crystal unit until the gate line is selected again. Thus, a display holding operation can be performed even if the liquid crystal does not have a memory property. In the reset, a predetermined signal data for reset is applied to the drain line, and a waveform for turning on the switch of the active element is applied at the timing shown in each embodiment. With the above configuration, a liquid crystal display device to which any of the driving methods according to the first to fourth embodiments is applied is realized.

Embodiment 8
The present embodiment is an example of an embodiment of a liquid crystal display device according to the present invention, and is a liquid crystal display device using the driving method of Embodiment 5 or 6. In the liquid crystal display device of this embodiment, electrodes are formed on each of the two support substrates, and an alignment film for aligning the liquid crystal is formed thereon. A liquid crystal is sandwiched between the pair of support substrates, and a pair of polarizing plates is provided outside the support substrate. Further, a light source for field sequential display is provided on one of the polarizing plates. With this configuration, a liquid crystal display device to which any of the driving methods according to the fifth and sixth embodiments is applied is realized.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.
Embodiment 1 This embodiment is an embodiment of the liquid crystal display device according to the present invention. In this embodiment, a chromium (Cr) line having a line width of 10 μm formed by a sputtering method is used for 480 gate bus lines and 640 drain bus lines, and silicon nitride (SiNx) is used for a gate insulating film. Using. The size of one unit pixel was 330 μm in length and 110 μm in width. A TFT (thin film transistor) was formed using amorphous silicon, and a pixel electrode was formed by sputtering using indium tin oxide (ITO) as a transparent electrode. The glass substrate on which the TFTs were formed in an array was used as the first substrate.

After forming a light-shielding film using chromium, a transparent electrode (common electrode) using ITO is formed on a second substrate facing the first substrate, and a color filter is formed into a matrix by a dyeing method. Then, a protective layer using silica was provided on the upper surface. Thereafter, a soluble polyimide was printed by a printing method and baked at 180 ° C. to remove the solvent. Polyamic acid was applied on the polyimide film by spin coating, baked at 200 ° C., and imidized to form a polyimide film. A buff cloth using nylon is wound around a roller having a diameter of 50 mm, and the number of rotations of the roller is 600 rpm, the stage movement speed is 40 mm / sec, the pushing amount is 0.7 mm, and the rubbing is performed twice so that 10 ° cross rubbing is performed. The polyimide film was rubbed. The thickness of the alignment film measured by the contact step meter was about 500 °, and the pretilt angle measured by the crystal rotation method was 1.5 degrees.

Micropearl, which is a spherical spacer having a diameter of about 2 μm, is sprayed on one of such a pair of glass substrates, and a thermosetting sealing material in which a cylindrical glass rod spacer having a diameter of about 2 μm is dispersed is applied to the other. did. These substrates were arranged so that the rubbing directions were cross-rubbed with each other by 10 ° so that the two substrates faced each other, and the sealing material was cured by heat treatment to assemble a panel having a gap of 2 μm. A V-shaped switching antiferroelectric liquid crystal composition shown on pages 61 to 64 of Asia Display 95 was injected between the panels in an isotropic phase (Iso) at 85 ° C. in a vacuum. The spontaneous polarization value of this liquid crystal was measured by applying a triangular wave, and was 165 nC / cm2. The response speed varied depending on the gradation voltage, but was between 200 microseconds and 800 microseconds. At 85 ° C., a rectangular wave having a frequency of 3 kHz and an amplitude of ± 10 V is applied to the entire surface of the panel using an arbitrary waveform generator and a high-power amplifier, and a rate of 0.1 ° C./min to room temperature while applying an electric field. And slowly cooled. A driver IC for driving was attached to the liquid crystal panel manufactured in this manner to obtain a liquid crystal display device.

駆 動 In this liquid crystal display device, the driving method of Embodiment 1 was applied. Specifically, one field period is set to 16.7 milliseconds, one frame period is set to 33.4 milliseconds, and the writing time of each scanning line is set to 4.2 microseconds, so that writing is performed eight times in one field. FIG. 10 shows the applied waveform and the change in transmittance measured for one pixel. 10A shows the drain applied voltage, FIG. 10B shows the gate applied voltage, and FIG. 10C shows the transmittance change. In the present embodiment, since the spontaneous polarization value of the liquid crystal is large, the change in the holding ratio due to the response of the liquid crystal after writing is large. As a result, the number of times of writing required for the transmittance to be in a stable state was eight times, which is larger than that in the first embodiment. According to this method, a liquid crystal display device utilizing a high-speed response in which all halftone responses are completed in one field without providing a frame memory regardless of the reset pulse method was obtained.

Example 2
This embodiment is another embodiment of the liquid crystal display device according to the present invention. In this embodiment, a TFT substrate and a CF (color filter) substrate were manufactured in the same manner as in the first embodiment, and the steps up to the assembly of the panel were performed in the same manner as in the first embodiment. A liquid crystal composition disclosed in Japanese Patent Application No. 9-093853 was injected into this panel in an isotropic phase (Iso) at 85 ° C. in a vacuum. Spontaneous polarization value of the liquid crystal composition to adjust the composition ratio so that the front and rear 20 nC / cm ^2, was actually measured by applying a triangular wave was 19.5nC / cm ^2. In addition, the response speed varied depending on the gradation voltage, but was between 600 microseconds and 2 milliseconds. After the injection, the mixture was gradually cooled to room temperature at a rate of 0.1 ° C./min. A driver IC for driving was attached to the liquid crystal panel manufactured in this manner to obtain a liquid crystal display device.

液晶 This liquid crystal display device was driven by the driving method of the first embodiment. Specifically, one field period is 16.7 milliseconds, one frame period is 33.4 milliseconds, the writing time of each scanning line is 11.5 microseconds, and writing is performed three times in one field. FIG. 11 shows the applied waveform and the change in transmittance measured for one pixel. 11A shows the drain applied voltage, FIG. 11B shows the gate applied voltage, and FIG. 11C shows the transmittance change. In this example, since the spontaneous polarization value of the liquid crystal was small, the change in the holding ratio due to the response of the liquid crystal after writing was small. As a result, the number of times of writing required for stabilizing the transmittance is three, which is smaller than that of the second embodiment. By reducing the required number of times of writing in this way, a decrease in the writing time can be suppressed as compared with the first embodiment. At the same time, the increase in the frequency of the driving circuit was suppressed, and the cost of the driving circuit was reduced. Also, it should be noted that although the response speed of the liquid crystal itself is slower than that of the first embodiment, the time required to reach a stable state is faster than that of the first embodiment when used in this driving method. is there. According to the present method as in the first embodiment, it is possible to obtain a liquid crystal display device utilizing the high-speed response in which all halftone responses are completed in one field without providing a frame memory regardless of the reset pulse method. Was.

Example 3
This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a TFT substrate was manufactured in the same manner as in Example 1. After forming a light-shielding film using chromium, a color filter is formed on the second substrate facing the TFT substrate by an ink jet method using a bubble jet (R) using a dye, and then ITO is formed. Was provided with a protective layer of silica. A buff cloth using rayon is wound around a roller having a diameter of 50 mm, and the number of rotations of the roller is 600 rpm, a stage moving speed is 40 mm / sec, a pushing amount is 0.7 mm, and the polyimide film is oriented in a direction such that parallel rubbing is performed when rubbing is performed twice. Was rubbed. The thickness of the alignment film measured by a contact step meter was about 500 °, and the pretilt angle measured by the crystal rotation method was 7 degrees. An ultraviolet curable resin in which a spherical glass spacer having a diameter of about 9.5 μm is dispersed on one of the pair of glass substrates and a cylindrical glass rod spacer having a diameter of about 9.5 μm is dispersed on the other. A sealing material was applied. These substrates were arranged so that the rubbing directions were parallel to each other so that the two substrates faced each other, and the sealing material was cured by a process of irradiating ultraviolet rays in a non-contact manner to assemble a panel having a gap of 9.5 μm. A nematic liquid crystal was injected into this panel. In the present embodiment, a compensating plate is added so as to be in an OCB (optically compensated birefrigence) display mode shown on pages 927 to 930 of S.I.D.94 Digest. A driving driver was attached to the liquid crystal panel manufactured in this manner to obtain a liquid crystal display device. Note that the response speed of the liquid crystal mode itself varies depending on the gradation voltage, but was between 1.5 ms and 4 ms.

This liquid crystal display device was driven by the driving method of the first embodiment. Specifically, one field period is 16.7 milliseconds, one frame period is 33.4 milliseconds, the writing time of each scanning line is 11.5 microseconds, and writing is performed three times in one field. The applied waveform was the same as in FIG. Since the response speed of the liquid crystal itself was slower than that of the second embodiment, the response of the transmittance was slightly slow. However, since the number of times of writing until reaching the stable state is small, the time until the stable state is reached is faster than that of the first embodiment in which the response speed is about five times faster. In the same manner as in the first and second embodiments, a liquid crystal display device utilizing the high-speed response in which all halftone responses are completed within one field without providing a frame memory irrespective of the reset pulse method according to the present method. was gotten.

Example 4
This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a liquid crystal panel was manufactured in the same manner as in Example 2, and a driving driver was further attached to obtain a liquid crystal display device. The driving method of the present liquid crystal display device is based on the driving method of the second embodiment. In the present embodiment, it was possible to take longer writing time per operation than in the second embodiment.

Example 5
This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a liquid crystal panel was manufactured in the same manner as in Example 2, and a driving driver was further attached to obtain a liquid crystal display device. The driving method of the present liquid crystal display device is based on the driving method of the fourth embodiment. In the present embodiment, it is possible to take longer write time per operation than in the fourth embodiment, which is not different from the normal AC drive. As a result, a low-cost and high-performance liquid crystal display device was realized without using a high-frequency element.

Example 6
This embodiment is still another embodiment of the liquid crystal display device according to the present invention. The configuration of the liquid crystal panel of this embodiment is the same as the configuration of the liquid crystal panel of the second embodiment. A field-sequential liquid crystal display device was formed by using a driving driver and a backlight capable of high-speed switching on the liquid crystal panel. In this liquid crystal display device, the driving method and the scanning of the luminance of the light source are based on the driving method of the fifth embodiment. Specifically, the number of times of writing with one polarity was four, and the scanning line was divided into two blocks. The display period 105 was 2 milliseconds, the writing time of each scanning line was 3.5 microseconds, and one frame period was 33.3 milliseconds. At this time, the lighting time of the light source could be secured twice, that is, 2.5 milliseconds, that is, 5 milliseconds for each color in one frame.

Example 7
This embodiment is still another embodiment of the liquid crystal display device according to the present invention. The configuration of the liquid crystal panel of the present embodiment is the same as the configuration of the liquid crystal panel of the second embodiment. A field-sequential liquid crystal display device was formed by using a driving driver and a backlight capable of high-speed switching on the liquid crystal panel. In this liquid crystal display device, the driving method and the scanning of the luminance of the light source are based on the driving method of the sixth embodiment. Specifically, the AC drive was performed twice in one frame, and the scanning line was divided into two blocks. The display period 105 was 7.7 milliseconds, the writing time of each scanning line was 3.5 microseconds, and one frame period was 33.3 milliseconds. At this time, the lighting time of the light source could be secured twice for each color, 2.5 milliseconds in one frame, that is, 8 milliseconds, which was longer than in the sixth embodiment.

Example 8
This embodiment is still another embodiment of the liquid crystal display device according to the present invention. In this example, a micro display was manufactured, and a reflection type projector was manufactured. It was fabricated in the same manner as a display display microdisplay as shown in the beginning of the January 1997 issue of Advanced Imaging. Specifically, a DRAM was manufactured by forming a MOS-FET on a silicon wafer according to the 0.8 μm rule. The size and the like were a die size of １ ／ inch, and a pixel pitch of about 10 μm formed a 1-Mega DRAM. The aperture ratio of the pixel was 90% or more. Further, the surface of the formed DRAM was planarized by applying a chemical mechanical polishing technique. On the other hand, a cover glass for microscopic observation was used for the facing substrate. A portion including a drive circuit was cut out from the silicon wafer, an alignment film was printed with a soluble polyimide, and baked at 170 ° C. to remove the solvent. A buff cloth using nylon was wound around a roller having a diameter of 50 mm, and the polyimide film was rubbed at a roller rotation speed of 600 rpm, a stage moving speed of 40 mm / sec, a pushing amount of 0.7 mm, and two rubbing times. The thickness of the alignment film measured by the contact step meter was about 500 °, and the pretilt angle measured by the crystal rotation method was 1.5 degrees.

{Circle around (2)} A photocurable sealing material in which a cylindrical glass rod spacer having a diameter of about 2 μm was dispersed was applied. These substrates were arranged so as to face each other, and the sealing material was cured by non-contact ultraviolet treatment to assemble a panel having a gap of 2 μm. The V-shaped switching antiferroelectric liquid crystal composition shown on pages 61 to 64 of Asia Display 95 was injected into this panel in an isotropic phase (Iso) at 85 ° C. in a vacuum. At 85 ° C., a rectangular wave having a frequency of 3 kHz and an amplitude of ± 10 V is applied to the entire surface of the panel using an arbitrary waveform generator and a high-power amplifier, and a rate of 0.1 ° C./min to room temperature while applying an electric field. And slowly cooled. Furthermore, a reflection type field sequential projector was manufactured using a light emitting diode of three colors, a collimating lens for obtaining parallel light, a polarization conversion element, a projection lens, and the like. The driving method of the liquid crystal display device is based on the driving method of the sixth embodiment. As a result of this method, a high-speed response projector display was obtained.

FIG. 1A is a waveform diagram illustrating the configuration and operation of the first embodiment, FIG. 1A is a waveform diagram of a data line applied voltage, FIG. 1B is a waveform diagram of a gate line applied voltage, and FIG. FIG. 2 is a diagram showing a change in transmittance when the voltages shown in FIGS. 1A and 1B are applied to a high-speed response liquid crystal. It is a figure which shows the time chart for every scanning line, and the display luminance for every scanning line. FIG. 3A is a waveform diagram illustrating the configuration and operation of the second embodiment, FIG. 3A is a waveform diagram of a data line applied voltage, FIG. 3B is a waveform diagram of a gate line applied voltage, and FIG. FIG. 4 is a diagram showing a change in transmittance when the voltages shown in FIGS. 3A and 3B are applied to the high-speed response liquid crystal. It is a figure which shows the time chart for every scanning line, and the display luminance for every scanning line. FIG. 9 is a diagram illustrating a configuration and an operation of a third embodiment, and is a diagram illustrating a time chart for each scanning line and a display luminance for each scanning line. FIG. 14 is a diagram for explaining the configuration and operation of the fourth embodiment, showing a time chart for each scanning line and a display luminance for each scanning line. FIG. 14 is a diagram illustrating the configuration and operation of a fifth embodiment, and is a time chart for each light source luminance and scanning line. FIG. 13 is a diagram illustrating a configuration and an operation of a sixth embodiment, and is a time chart for each light source luminance and a scanning line. FIG. 14 is a cross-sectional view illustrating a layer structure of a liquid crystal display device according to a seventh embodiment. 10A and 10B are diagrams illustrating the operation of the liquid crystal display device according to the first embodiment. FIG. 10A is a waveform diagram of a data line applied voltage, FIG. 10B is a waveform diagram of a gate line applied voltage, and FIG. It is a figure which shows the change of the transmittance | permeability when the voltage of 10 (a) and (b) is applied. 11A and 11B are diagrams illustrating the operation of the liquid crystal display device according to the second embodiment. FIG. 11A is a waveform diagram of a data line applied voltage, FIG. 11B is a waveform diagram of a gate line applied voltage, and FIG. It is a figure which shows the transmittance | permeability change at the time of applying the voltage of (a) and (b). FIG. 12A is a diagram illustrating a data signal waveform in a conventional AC driving method. FIG. 12A is a waveform diagram of a data line applied voltage, FIG. 12B is a waveform diagram of a gate line applied voltage, and FIG. FIG. 13 is a diagram showing a change in transmittance when the voltages shown in FIGS. 12A and 12B are applied to the high-speed response liquid crystal. FIG. 13 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line in the conventional AC driving method of FIG. 12. FIG. 9 is a diagram illustrating a temporal change in luminance when the reset method driving is applied to the conventional OCB mode. FIG. 15 (a) is a diagram for explaining a data signal waveform by a conventional pseudo DC driving method, FIG. 15 (a) is a waveform diagram of a data line applied voltage, FIG. 15 (b) is a waveform diagram of a gate line applied voltage, and FIG. 15 (c). FIG. 17 is a diagram showing a change in transmittance when the voltages shown in FIGS. 15A and 15B are applied to the high-speed response liquid crystal. FIG. 16 is a diagram showing a time chart for each scanning line and a display luminance for each scanning line in the conventional pseudo DC driving method of FIG.

Explanation of reference numerals

5 Polarizing plate 6 Substrate 7 Electrode 8 Alignment film 9 Liquid crystal 101 Positive writing 102 Positive display 103 Negative writing 104 Negative display 105 Display period

Claims (7)

In a liquid crystal display device having a response speed faster than one frame time, one frame is composed of an odd field and an even field, and predetermined gradation voltage data is written a plurality of times in the odd field, and then the gradation is formed in the even field. A method for driving a liquid crystal display element, comprising writing a plurality of times of gradation voltage data in which a voltage order is inverted. A method of driving a liquid crystal display element having a response speed faster than one frame time, wherein data is written a plurality of times in one frame with grayscale voltage data in which a voltage sequence for grayscale is inverted at a predetermined cycle. . 3. The method according to claim 1, wherein the scanning line group is divided into a plurality of blocks, and the plurality of blocks are scanned simultaneously. A driving method for a color field sequential liquid crystal display device in which one frame is divided into a plurality of subfields according to a plurality of colors, and data of each color is sequentially displayed in each subfield, wherein the driving method for each color is claimed. Item 4. A method for driving a liquid crystal display device according to the method for driving a liquid crystal display element according to Item 3. 4. A liquid crystal display device comprising a liquid crystal display device, wherein the liquid crystal display device is driven by the method for driving a liquid crystal display device according to claim 1. 5. A color field sequential liquid crystal display device in which information of a plurality of colors is sequentially displayed in one frame, wherein the color field sequential liquid crystal display device is driven by the driving method of the liquid crystal display device according to claim 4. . A reflective field sequential projector using the liquid crystal display device according to claim 6.

Images