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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display apparatus, and particularly, to a liquid crystal display apparatus of an active matrix method in which a switching element is provided for each pixel, and also relates to a driving method
of a liquid crystal display apparatus in which a switching element for selection is provided for each pixel or each scanning line.
2. Description of the Related Art
Generally, in a liquid crystal display (LCD) apparatus in which pixel electrodes are formed of switching elements provided at cross portions where signal lines and scanning lines have contact with each other and in which the pixel electrodes are
arranged in a matrix, thin film transistors (TFTs) are broadly used as switching elements. A TFT used in this kind of TFT-LCD is an element consisting of three terminals, i.e., drain, gate, and source electrodes which are respectively connected with a
signal line for supplying a display signal, a scanning line for supplying a scanning signal, and a pixel electrode forming a pixel. Therefore, in order to write a display signals into each pixel electrode, a display signal and a scanning signal are
respectively applied to the drain and gate electrodes, so that writing is performed by rendering a path between the drain and source electrodes of the TFT electrically conductive. Further, to maintain display signals at respective pixel electrodes, a
scanning signal is not applied to the gate electrode, and the electric conductance between the drain and source electrodes is reduced.
Conventionally, circuits for supplying display and scanning signals to be applied to TFTs (e.g., a display signal drive circuit and a scanning signal drive circuit) adopt a specific circuit configuration and use an integrated drive circuit (or
IC). Thus, since a specific drive IC is used, withstanding characteristics of the IC are limited due to the process of manufacturing the IC and sufficient drive characteristics for all TFT-LCD cannot be obtained. For example, if TFT-LCDs are improved
to attain high precision and the time required for scanning pixels is thereby shortened, sufficient conductive characteristics cannot be obtained, or if the scanning cycle is lengthened or the TFT-LCD is used in a severe environment, sufficient
maintenance characteristics cannot be obtained. In these cases, display images are deteriorated or the TFT-LCD is deteriorated.
FIGS. 1A-1C are diagrams showing potential waveforms of respective electrodes in case of a frame inversion driving generally used to perform alternate current driving. The above problems will be explained with reference to FIGS. 1A-1C and 2. In
a TFT-LCD, alternate current driving is performed so that liquid crystal may not be degraded by a direct current component. FIGS. 1A-1C show electric potential waveforms of respective electrodes in frame inversion drive which is generally used to
perform alternate current drive. In FIG. 1A, reference +Vsig denotes a potential of positive polarity, reference -Vsig denotes a potential of negative polarity, reference Vsc denotes a center potential when a display signal is converted into an
alternate current, and reference Vg denotes a scanning signal waveform. FIG. 1B shows a waveform of a pixel signal Vp which is retained by a pixel, and FIG. 1C shows a waveform of a potential difference Vg-Vsig between the pixel potential and the
scanning signal waveform Vg.
FIG. 2 shows general characteristics of a TFT used as a switching element of a TFT-LCD. In FIG. 2, the lateral axis Vgs represents a voltage between the source and the gate of the TFT, i.e., a potential difference between the pixel potential Vp
and the scanning signal Vg. In FIG. 2, the longitudinal axis Id denotes a drain current of the TFT, i.e., a current amount flowing between the pixel electrode and the display electrode. As is apparent from this figure, when a display signal is written,
the amount of Id is greater as the voltage VGs is higher than 0[V], and the TFT is therefore rendered more conductive. When a display signal is maintained, the amount of ID is smaller when the voltage Vgs is lower than 0[V], and the maintenance
characteristics of the TFT are improved.
However, in case of an actual TFT-LCD as shown in FIG. 1C, when a display signal of positive polarity is written, the potential difference Vgh-Vsig which corresponds to +Vgs of FIG. 2 decreases to be close to 0[V], and therefore, conductive
characteristics of a TFT are degraded. When a display signal of negative polarity is maintained, the potential difference Vgl-Vsig which corresponds to -Vgs of FIG. 2 decreases to be close to 0[V], and therefore maintenance characteristics of the TFT is
degraded.
Deterioration in conductive characteristics and maintenance characteristics as stated above is caused due to the narrow voltage range of the scanning signal Vg, i.e., the narrow dynamic range which greatly influences the conductive
characteristics and maintenance characteristics, as is apparent from examples of FIGS. 1A-1C and 2. In addition, as explained above, the scanning signal drive circuit is integrated as an IC, and the dynamic range is decided by voltage-withstanding
characteristics by means of the IC process. Therefore, as long as a scanning signal drive IC is still used without changes as in a conventional apparatus, the conductance characteristics (i.e., the writing characteristics and the maintenance
characteristics) are consequently deteriorated so that image quality of a display image is degraded. Further, since liquid crystal cannot be completely driven by an alternate current, a voltage of a direct current is applied to the liquid crystal so
that the TFT-LCD itself is disadvantageously degraded.
Meanwhile, as LCDs have been improved to have a higher resolution (i.e., to have more pixels) in recent years, the driving frequency has been increased to achieve high speed processing. In these circumstances, in order to make a driving IC be
driven with a lower voltage so as to comply with operation of a high speed signal, proposals have been made to disclose common inversion driving (Jpn. Pat. Appln. KOKAI Publication No. 55-28649) for shifting a common electrode potential to an opposite
polarity to the polarity of an image and source level shift driving (Japanese Patent Application No. 4-48313) for shifting a source voltage in accordance with polarity of an image. However, in common inversion driving, a common driver of a large
capacitance must be driven at a horizontal driving cycle (of 15 to 30 micro seconds), and therefore, the power consumption is increased. In source level shift driving, since a large source capacitance must be driven, a strong driving circuit is
therefore required and it is difficult to adopt this driving in an apparatus in which the power source must be driven with a high speed to perform dot inversion. Therefore, this source level shift driving is limited to signal line inversion driving.
The signal line inversion driving is characterized in that a lateral cross talk does not easily occur due to an increase in resistance of the common electrode when the screen size is enlarged, and in that a longitudinal cross talk easily occur due to
leakage from a TFT. Therefore, requirements for TFT characteristics are severe.
As a method for solving problems as stated above, a method has been proposed in which a switch is provided in a driving IC to switch signal lines for every field while maintaining the power source at a constant level (Jpn. Pat. Appln. KOKAI
Publication No. 3-51887 and Japanese Patent Application No. 1-188299). However, in this method, the yield is lowered since the internal circuits of the liquid crystal panel must be newly designed and added, and since a high speed operation of a newly
provided switch is requested a high performance device such as polysilicon etc., not amorphous silicon, is required and manufacturing processes become complicated.
Further, in recent years, another driving method (i.e., an MF driving method) has been proposed (Japanese Patent Application 2-69706). Although this MF driving method is effective for reducing power consumption and is also effective for surface
flicker, the flicker component for every pixel is increased since maintenance time is greatly increased. Therefore, there is a problem in that this causes lateral stripes for each field to be visible to the eye, thereby causing deterioration of image
quality of a standstill image.
Meanwhile, since a liquid crystal display apparatus is thin and lightweight and since the apparatus can be driven with a low voltage, the apparatus can be broadly used for devices beginning with a wrist-watch and a portable calculator and further
including game devices of a small size. Further, the need for pen inputting electronic pocket notebooks have increased, so that demands on portable data access terminals are increased.
As a result of developments in multi-media, a plurality of images are displayed on one single screen. Since a large-size screen and high precision are required, the amount of data increases and the driving frequency increases. As a result of
this, an increase in the power consumption has become a problem, and therefore, a driving method has been proposed by the present inventors to lower the power consumption (e.g., Japanese Patent Application No. 2-69706). This method in which the driving
frequency is reduced by dividing a sheet of field image into an odd number of sub-fields is called an MF driving method. Although the MF driving method is very effective for reducing surface flicker, the maintenance period is greatly increased so that
the flicker component for every pixel (normally for every line) is increased. Therefore, there is a problem in that this causes lateral stripes (or a line interruption) for every field to be visible to the eye, thereby causing deteriorating of image
quality of a standstill image.
Further, it has been apparent from experiments that in a high precision image which is not interrelate with an image, respective flicker components are not compensated for, and of the flicker components, new carriers caused by differences between
positive and negative polarities occur on a spatial frequency axis, thereby producing a reflected distortion. Since this reflected distortion is not standstill but is moving, it causes severe deterioration in image quality when the distortion enters
into an area which can be viewed in accordance with time-spatial frequency characteristics of human visual perception.
As has been explained above, in the MF driving method, line disturbances and reflected distortion caused thereby deteriorate the image quality. Normally, to correct such deterioration, a correction is performed during a blanking period (or a
fly-back period), but this correction is not sufficient.
Further, since the MF driving method deteriorates image quality of motion pictures since liquid crystal achieves poor response when motion pictures are displayed, and since an interval with which one pixel is driven is longer than one field, a
interruption occurs, which an image is interlaced and disturbed to be comb-like, thereby deteriorating the image quality. In addition, with respect to a moving picture, there is another problem in that the driving frequency is decreased so that signals
cannot be sufficiently rewritten and a residual image appears. Therefore, to deal with a moving picture, means of signal processing system is optionally required.
Thus, in an active matrix LCD using switching elements such as TFTs, even if the dynamic range of a scanning signal driving IC (which is decided by the manufacturing process of the scanning signal driving IC) is directly used without changes,
deterioration of conductivity characteristics of a TFT and of maintenance characteristics is caused, so that not only is the image quality of a display image is degraded, but also the liquid crystal cannot be completely driven by an alternate current.
Therefore, a direct current voltage component is applied to the liquid crystal, and the liquid crystal itself is degraded.
In addition, as the speed of the driving frequency is increased to achieve a high resolution, an increase in the power consumption is caused or the image quality is degraded by lateral cross talk and longitudinal cross talk. Further, in the MF
driving method, by which the power consumption can be reduced, there is a problem in that line flickers of a standstill picture increase thereby causing line disturbances since a standstill image has a long maintenance period, while image quality of a
moving picture is degraded since a preceding field remains with a comb like appearance.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above situation, and has an object to provide a liquid crystal display apparatus which is capable of preventing deterioration in writing characteristics and maintenance characteristics due to the
narrow dynamic range of a scanning signal driving IC decided by the manufacturing process of the scanning signal driving IC and also preventing the liquid crystal from being degraded, thereby ensuring high image quality and long life-time.
In addition, the present invention has another object to provide a liquid crystal display device whose power consumption is small and is capable of reproducing an image of high quality regardless of whether the image is a moving picture or a
standstill picture.
The present invention has further another object to provide a driving method of a liquid crystal display apparatus for changing, among flicker component which cannot be sufficiently compensated for, reflected distortions caused by a difference
between positive and negative polarities into an effect which is not visible with the eye, due to the time-spatial frequency characteristics of human visual perception.
The present invention has further another object to provide a driving method of a liquid crystal display apparatus for performing random driving according to certain signals, with respect to data such as a moving picture which has a frequency
higher than the driving frequency, in order to restrict occurrences of residual image phenomena.
According to an aspect of the present invention, there is provided a liquid crystal display comprising: a plurality of sub-fields forcing one frame image separately, each sub-field being driven independently; means for driving each sub-field
according to a predetermined drive scheme; and means for controlling an operation of the driving means.
According to another aspect of the present invention, there is provided a liquid crystal display apparatus comprising: a plurality of signal lines and scanning lines which are arranged so as to extend in directions orthogonal to each other and
cross each other; pixel electrodes respectively provided at cross portions so as to form a matrix arrangement; and thin film transistors respectively provided between the pixel electrodes and the signal lines and having gates connected with the scanning
lines, for functioning as switches for writing image signals into the pixel electrodes, characterized in that there is provided gate signal change means for making gate voltages or On-times of the gates of the thin film transistors change in accordance
with signals which determine at least one of a writing-time, a maintenance time, and a scanning method.
Hence, the following are cited as preferred embodiments of the present invention. (1) Gate signal change means changing, as a control signal, an output of a standstill/moving detection circuit for determining whether an inputted image is a
standstill picture or a moving picture. (2) A gage signal is controlled such that the number of lines to be driven differs between when an inputted image is a standstill picture and when an inputted image is a moving picture. (3) Gage signal change
means including at least a circuit for changing a source voltage of a gate driving circuit. (4) A period or changing a gate signal is a period in which an image signal is not outputted to a signal line. (5) The OFF-level of a gate is shifted from the
OFF-level corresponding to a minimum value of a flicker.
According to still another aspect of the present invention, there is provided a liquid crystal display apparatus comprising: a plurality of signal lines and scanning lines which are arranged so as to extend in directions orthogonal to each other
and cross each other; pixel electrodes respectively provided at cross portions so as to form a matrix arrangement; and switching elements respectively connected between the pixel electrodes and the signal lines and controlled by the scanning lines,
wherein the switching elements perform operation of writing display signals when scanning signals are applied to the scanning lines, and the switching elements perform operation of maintaining the display signals thereby displaying an image when scanning
signals are not applied to the scanning lines, characterized in that there is provided scanning signal control means for controlling the scanning signals such that the switching elements have a higher conductivity characteristic during the operation of
writing the display signals and such that the switching elements have a higher cut-off characteristic during the operation of maintaining the display signals.
Hence, the followings are cited as preferred embodiments of the present invention. (1) Switching elements are TFTs each having a source, a drain, and a gate respectively connected to a pixel electrode, a signal line, and a scanning line. (2)
Scanning signal control means performs control such that a maximum value of an electric potential on the positive side of a withstanding voltage characteristic with respect to a grounding potential of a scanning electrode deriving circuit which supplies
a scanning signal is outputted during operation of writing the display signal, and such that a maximum value of an electric potential on the negative side of the withstanding voltage characteristic with respect to the grounding potential is outputted
during operation of maintaining the display signals. (3) Scanning signal control means controls a plurality of scanning electrode driving circuits, in such a manner in which the grounding potential and operating potential of each scanning electrode
driving circuit are made variable during both the operation of writing the display signals and the operation of maintaining the display signals. (4) Scanning signal control means controls a plurality of scanning electrode driving circuits, in such a
manner in which the operational potential of the scanning electrode driving circuit is made variable for each of the scanning electrode driving circuit.
According to the liquid crystal display apparatus of the present invention, scanning signals are controlled such that the voltage-withstanding characteristic of a scanning signal driving circuit or the like is shifted to the positive side during
operation of writing display signals, thereby to raise the conductivity characteristic of switching elements respectively provided or pixels, while the voltage-withstanding characteristic of the scanning signal driving circuit or the like is shifted to
the negative side during operation of maintaining display signals, thereby to raise the cut-off frequency characteristic of the switching elements for every pixel. As a result, the dynamic range of the scanning signal driving circuit or the like can be
equivalently enlarged. Further, by preventing deterioration of the writing characteristic and the maintenance characteristic of switching element TFTs due to the narrow dynamic range inherent to a scanning signal driving IC, deterioration in image
quality of a display image and deterioration of a liquid crystal itself can be prevented, so that a liquid crystal display apparatus having a high quality image and a long life time can be realized.
In addition, according to the liquid crystal display apparatus of the present invention, the leakage current characteristic and the ON-current characteristic of a TFT which cause a cross talk and a flicker can be controlled optimally in
accordance with a driving time and a maintenance time, so that it is possible to reduce longitudinal cross talk or the like and to obtain high quality images while preserving an advantage of low power consumption.
Next, in the driving method according to the present invention, a display apparatus for displaying an image by means of A pixels or scanning lines which are respectively provided with selection switch elements is arranged such that a sheet of
frame image is divided into n sub-fields which are displayed sequentially along the time axis and each of the sub-fields is basically formed of A/n.times.m pixels or scanning lines among the A pixels or scanning lines (where A is a positive integer, n is
a positive integer which is equal to 3 or more and is equal to A or less, and m is a positive integer equal to n or less). To improve image quality, it is desirable if flickers can be compensated for between a pixel or scanning line on which writing is
to be performed and pixels or scanning lines adjacent to the pixel or scanning line. When an image is displayed by scanning lines, image signals of a sheet of a frame image can be subjected to interlace processing with a ratio of n:m, and the switching
elements can be selectively driven in accordance with image signals thus precessed.
According to still further aspect of the present invention, there is provided a driving method used in a display apparatus for displaying an image by means of A pixels or scanning lines which are respectively provided with selection switch
elements, characterized in that a sheet of frame image is divided into n sub-fields which are displayed sequentially along a time axis, each of the sub-fields is basically formed of A/n.times.m pixels or scanning lines among the A pixels or scanning
lines (where A is a positive integer, n is a positive integer which is equal to 3 or more and is equal to A or less, and m is a positive integer equal to n or less), and an interval between the pixels and scanning lines is changed for every sub-field or
in one sub-field.
According to still further aspect of the present invention, there is provided a driving method used in a display apparatus for displaying an image by means of A pixels or scanning lines which are respectively provided with selection switch
elements, characterized in that a sheet of frame image is divided into n sub-fields which are displayed sequentially along a time axis, each of the sub-fields is basically formed of A/n.times.m pixels or scanning lines among the A pixels or scanning
lines (where A is a positive integer, n is a positive integer which is equal to 3 or more and is equal to A or less, and m is a positive integer equal to n or less), and the value of m/n is changed depending on the video signal.
According to still further aspect of the present invention, there is provided a driving method used in a display apparatus for displaying an image by means of A pixels or scanning lines which are respectively provided with selection switch
elements, characterized in that a sheet of frame image is divided into n sub-fields which are displayed sequentially along a time axis, each of the sub-fields is basically formed of A/n.times.m pixels or scanning lines among the A pixels or scanning
lines (where A is a positive integer, n is a positive integer which is equal to 3 or more and is equal to A or less, and m is a positive integer equal to n or less), and the sub-fields are grouped along the time-axis, so that a value of m/n differs
between groups of the sub-fields. To compensate for changes in luminance on the screen caused by switching the value m/n, there can be provided means for detecting the screen luminance of a preceding sub-field prior to the switching of the value m/n,
thereby to provide feed-back on the screen luminance of a next sub-field.
According still further aspect of the present invention, there is provided a driving method used in a display apparatus for displaying an image by means of A pixels or scanning lines which are respectively provided with selection switch elements,
characterized in that a sheet of frame image is divided into n sub-fields which are displayed sequentially along a time axis, each of the sub-fields is basically formed of A/n.times.m pixels or scanning lines among the A pixels or scanning lines (where A
is a positive integer, n is a positive integer which is equal to 3 or more and is equal to A or less, and m is a positive integer equal to n or less), and writing can be selectively performed with respect to displacement pixels or scanning lines among
those pixels or scanning lines which do not belong to pixels or scanning lines of displayed sub-fields. It is possible to include a function of performing writing again to compensate for unevenness in luminance when writing is not performed with respect
to a pixel or scanning line for several frames.
In the above aspects of the present invention, it is desirable to make intervals between pixels or scanning lines change for every sub-field.
According to the driving method of the liquid crystal display apparatus of the present invention, switch elements are not cyclically turned on and off in view of both the spatial cycle and the time-based cycle. Consequently, intervals between
pixels or scanning lines are irregularly changed. As a result, changes in luminance of pixels, for example, which are caused by the maintenance characteristic of a liquid crystal, do not have a spatial cycle or a time-based cycle, and therefore, either
the changes in luminance do not fall within a range which can be observed with the eye, or the changes can only be observed with difficulty. For example, when image signals are subjected to interlace precessing with a ratio of n:m to display an image by
means of scanning lines, a selected scanning line interval irregularly changes within one frame. Since scanning lines which are turned on during a field period therefore do not have a spatial cycle, either changes in luminance of pixels caused by the
maintenance characteristic of liquid crystal do not fall within a range which can be observed with the eye, or the changes can only be observed with difficulty. Further, in the case of a highly precise image which does not have an interrelation between
images, when new carriers which are caused by a difference between flicker components of positive and negative polarities occur on a spatial frequency axis, thereby generating a reflected distortion, such a reflected distortion does not occur with a
spatial cycle and therefore, does not fall within a range which can be observed with the visual time-spatial characteristics of the eye, or the changes can only be observed with difficulty. As a result, it is possible to greatly reduce deterioration of
image quality.
Further, according to the driving method of the liquid crystal display apparatus of the present invention, for example, the value of m/n can be suitably changed with respect to a moving picture of a standstill picture.
Furthermore, according to the driving method of the liquid crystal display apparatus of the present invention, in cases where image signals which tend to easily generate flickers when driven at a predetermined constant value of m/n are inputted,
the value of m/n is switched for each sub-field group and therefore, occurrences of patterns of flicker differ between groups, so that flickers are observed with difficulty. In the second and third aspects, if the screen luminance of a preceding
sub-field prior to switching is detected and feedback is applied to the screen luminance of a next sub-field, changes in luminance of the screen can be compensated for by changing the value of m/n.
Still further, according to the driving method of the liquid crystal display apparatus of the present invention, for example, it is possible to eliminate residual images caused due to differences in luminance. With respect to images such as a
moving picture and the likes whose data have a frequency higher than the driving frequency of a moving picture, image signals of one frame are sub-sampled and displayed, and therefore, image signals of one frame are divided into a plurality of
sub-fields. As a result, pixels onto which signals have been once written maintain an image as once written during a non-selection period until signals are written again into the pixels, so that even if signals extremely different from the signals as
once written are inputted, the such signals are not written but appear as residual an image. Therefore, driving is selectively performed with respect to those signals whose luminance level differs between a preceding frame and a next frame, so that
residual images are prevented from being generated.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention
may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of
the preferred embodiments given below, serve to explain the principles of the invention.
FIGS. 1A-1C are diagrams showing potential waveforms of respective electrodes in case of a frame inversion driving generally used to perform alternate current driving;
FIG. 2 is a graph showing general characteristics of a TFT used as a switching element;
FIG. 3 is a block diagram showing a basic structure of a liquid crystal display apparatus according to a first embodiment of the present invention;
FIG. 4 is a diagram showing an example of a scanning electrode control circuit used in a first embodiment;
FIGS. 5A and 5B are timing chats showing examples of scanning signals where a scanning electrode drive circuit and a scanning electrode control circuit are used in the first embodiment;
FIGS. 6A-6C are timing charts showing potentials of respective electrodes of a TFT-LCD panel where the output dynamic range of the scanning electrode driving circuit is increased in the first embodiment;
FIG. 7 is a diagram showing an example of structure of a scanning electrode control circuit 5 used in a second embodiment;
FIG. 8 is a diagram showing an example of structure of a level shift circuit in the second embodiment;
FIG. 9 is a diagram showing an example of structure of a scanning electrode control circuit used in a third embodiment;
FIG. 10 is block diagram showing an example of circuit configuration in a fourth embodiment;
FIG. 11 is a timing chart showing driving voltages of gates in the fourth embodiment;
FIG. 12 is a block diagram showing a circuit configuration in a fifth embodiment;
FIG. 13 is a timing chart showing driving voltages of gates in the fifth embodiment;
FIG. 14 is a timing chart showing driving voltages of gates in a sixth embodiment;
FIG. 15 is a graph showing a relationship between the flicker amount and the presence of disturbance stripes;
FIGS. 16 show the concept of an MF driving method;
FIGS. 17A and 17B are graphs showing potential change waveforms and flicker components;
FIGS. 18A and 18B are graphs showing flicker components during MF driving;
FIG. 19 is a graph showing frequency spectra of luminance changes;
FIGS. 20A and 20B are diagrams showing the structure of a main part of the liquid crystal display apparatus according to the seventh embodiment of the present invention;
FIG. 21 shows sub-fields of the driving method according to the seventh embodiment of the present invention;
FIGS. 22A and 22B are diagrams showing the structure of a main part of the liquid crystal display apparatus according to the eight embodiment of the present invention;
FIG. 23 shows sub-fields of the driving method according to the eight embodiment of the preset invention;
FIG. 24 is a timing chart showing driving signal voltages and timings in the driving method according to the eight embodiment of the present invention;
FIGS. 25A and 25B compare the driving method according to the eight embodiment of the preset invention with a conventional MF driving method, with respect to phenomena of flowing lateral strips;
FIG. 26 shows display images when image signals are switched in a moving picture;
FIG. 27 is a block diagram showing the structure of a main part of a liquid crystal display apparatus according to the ninth embodiment of the present invention;
FIG. 28 is a block diagram showing the structure of a main part of a liquid crystal display apparatus according to the tenth embodiment of the present invention;
FIG. 29 shows sub-fields of the driving method according to the eleventh embodiment of the present intention; and
FIG. 30 is a block diagram showing the structure of a main part of a liquid crystal display apparat | | |
