JPH06342148A - Display controller - Google Patents

Abstract

PURPOSE:To substantially speed up animation image display such as moving a cursor even at a low-frame frequency while making stable static image display by generating an address signal for selecting only the scanning electrodes and an image information signal for rewriting display images in accordance with a change of the information stored into a memory. CONSTITUTION:Scanning electrode address data for assigning the scanning electrodes 12C and video data are first outputted from a main apparatus 14 through four pieces of signal lines PD0 to PD3 to a control circuit 15. The scanning electrode address data arranged on the signal lines PD0 to PD3 are extracted and simultaneously stored by this control circuit 15. The data are outputted during the horizontal scanning period to a scanning electrode driving circuit 12 at the time of driving the assigned scanning electrodes 12C. On the other hand, the video data are inputted to a shift register 13A in an information electrode driving circuit 12 and are shifted by every four pixels by a transfer clock CLK, by which the video data of the number of the pixels corresponding to information electrodes 13D (2560 pieces) are separated and are transmitted to a line memory 13B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display control device.

[0002]

2. Description of the Related Art A CRT (cadre ray tube) for forming an image by utilizing the afterglow characteristic of a phosphor and an image for forming an image by utilizing a transmitted light quantity characteristic according to an effective value of a driving voltage.
N (twisted nematic) LCD (liquid crystal element)
In view of display principles, it is necessary to keep the frame frequency, which is one screen forming frequency, above a certain value. It is generally 30
The frame frequency is equal to or higher than Hz, and this frame frequency can be expressed by the reciprocal of the product of the number of scanning lines forming the display unit and the horizontal scanning time for scanning this. At present, as a scanning method, an interlace method and a non-interlace method are known. As other methods, a pairing method and a simultaneous parallel scanning method by dividing a fraction, although limited to an LCD, have been proposed and put into practical use. In the NTSC standard, 2 fields / with a frame frequency of 30 Hz
Frame interlace method, horizontal scanning time is about 6
It is 3.5 μsec, and the number of scanning lines is about 480 (the number of effective display lines). In the TN LCD, the number of scanning lines is 200 to 400 and the frame frequency is a non-interlace system of 30 Hz or more. In addition, in CRT, the frame frequency is 40 to 60 Hz separately from the NTSC standard.
A non-interlaced method is also used, and the number of scanning lines is about 200 to 1000.

Now, let's consider driving a CRT and a TN type LCD each having a vertical (scanning line) 1920 × horizontal 2560 pixels. When the frame frequency is 30Hz and the interlace system is used, the horizontal scanning time is about 17.5μ.
sec, the horizontal dot clock frequency is about 147
MHz (horizontal retrace time in CRT is not considered). In the case of a CRT, the horizontal dot clock frequency of 147 MHz has a very high beam scanning speed, which greatly exceeds the maximum electron beam modulation frequency of the electron gun in the current picture tube, and an accurate image can be obtained even if scanning is performed at 17.5 μsec. I can't. 192 for TN LCD
The zero scanning line drive corresponds to the duty ratio 1920, and the current maximum duty ratio of about 400 is largely exceeded, and display cannot be performed. Therefore, considering that the horizontal scanning time is set to a realistic value for driving, the frame frequency is now 3
The frequency becomes smaller than 0 Hz, so that the scanning state is visually recognized and flicker occurs, and the display quality is significantly impaired. As described above, the large screen and high density of a CRT or TN type LCD are currently reaching the limit because the number of scanning lines cannot be increased sufficiently due to restrictions of the display principle and driving elements.

By the way, in recent years, Clark and Lagerwell announced a ferroelectric liquid crystal device having a high-speed response and a memory property in US Pat. No. 4,367,924.

This ferroelectric liquid crystal device generally has a chiral smectic C phase (SmC ^* ) in a specific temperature range.
Or, having an H phase (SmH ^* ), in this state, in response to an applied electric field, one of the first optically stable state and the second optically stable state, and when no electric field is applied Has the property of maintaining its state, that is, bistability, and has a quick response to changes in the electric field, and is expected to be widely used as a high-speed and memory type display element.

However, it is generally difficult for the ferroelectric liquid crystal element to have the bistability proposed by Clark et al., And there is a strong tendency to have the monostable state. Clark et al. Used an orientation control method by applying shearing force by a shear ring or applying a magnetic field in order to realize permanent bistability, but from the viewpoint of production technology, as an orientation control method, A method of applying a uniaxial orientation treatment such as a rubbing treatment or an oblique vapor deposition treatment to the substrate is advantageous. A ferroelectric liquid crystal element whose orientation is controlled by applying such a uniaxial orientation treatment to a substrate may not cause permanent bistability. The orientation state in which this permanent bistability does not occur, that is, the so-called monostable orientation state, is in the range of several msec to several hours,
It has a property that biaxial orientation when an electric field is applied changes to uniaxial orientation when no electric field is applied. Therefore, in a display device using this monostable ferroelectric liquid crystal element,
There was a problem that it disappears with the release of the electric field. In particular, during multiplexing driving, the writing state of pixels on scan lines that are not accessed may gradually disappear.

In view of this problem, a voltage signal that causes "black" and a voltage signal that causes "white" are selectively applied to the pixels on the selected scanning line to sequentially select the scanning lines. A driving method (refresh driving) in which writing is performed by repeating this cycle when the cycle is one frame or one field is considered. By adopting such a refresh driving method, the variation in the amount of transmitted light of the non-selected pixels is very small, and even when the frame frequency is lower than 30 Hz,
It was possible to eliminate the occurrence of visual recognition of the write scan line (the scan write line has higher brightness than other lines and can be visually easily discerned) and flicker. At this time, according to the study by the present inventors, it was confirmed that the same effect is obtained even with a frame frequency of about 5 Hz.

[0008] The above facts cause problems for a large screen and a high definition, which are caused by the above-mentioned indispensable condition of driving at a frame frequency of 30 Hz or higher, which is a limitation of the CRT and TN type LCD. It is effective in breaking all at once.

[0009]

However, in the case of refresh driving at a low frame frequency as described above, in order to perform so-called moving image display such as character editing and smooth scrolling or cursor movement on a graphics screen, the display speed is May be slow and display performance may be degraded.
For example, a display device using a ferroelectric liquid crystal element is a display device capable of achieving a large screen and high definition far exceeding conventional display devices (CRT, TN type LCD, etc.).・ The frame frequency has become lower due to the higher definition, which sometimes slows down the speed of smooth scroll and cursor movement.

In recent years, computers and their peripheral circuits and software have been remarkably developed. Especially for large screens and high-definition displays, a display method for displaying a plurality of screens in a display area, which is called multi-window, has become popular. is doing. Therefore, a display device suitable for such a multi-window is desired.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and in particular, a stable still image display can be achieved even in a display device using a ferroelectric liquid crystal element which easily exhibits monostability. The present invention provides a display device, a drive control device thereof, and a display method for substantially speeding up cursor movement, smooth scrolling, moving image display such as multi-window, or video moving image display even under a low frame frequency (30 Hz or less). Especially.

In a display control device for forming a display image on a display means in which a plurality of scan electrodes and a plurality of information electrodes are arranged in a matrix, the plurality of scan electrodes are sequentially selected and the plurality of information electrodes are selected. A memory for storing information displayed by refresh driving means for repeatedly applying a signal, a means for changing the information stored in the memory, and a display area of the display means based on the change of the information. It is characterized by comprising an address signal for selecting only a part of the scan electrodes and a means for generating an image information signal for rewriting the display image of the part.

[0013]

According to the present invention, even if the display screen is partially rewritten, the background display quality is maintained and the rewriting can be performed at high speed.

[0014]

1 is a block diagram of a liquid crystal display device according to the present invention and a main body device for controlling driving. FIG. 2 shows a timing chart of the display information signal. The display panel 11 is composed of scanning electrodes 12C (1920) × information electrodes 13D (2560).
Book), a ferroelectric liquid crystal is enclosed in the matrix structure, and the scan electrode drive circuit 12 is connected to the scan electrode 12C.
The information electrode drive circuit 13 is connected to the information electrode 13D. The scan electrode drive circuit 12 includes a decoder 12A and an output stage 12B.
The information electrode drive circuit 13 is provided with a shift register 13A, a line memory 13B and an output stage 13C.

First, the scan electrode address data designating the scan electrode 12C and the video data are transferred to four signal lines PD0,
The data is output from the main body device 14 to the control circuit 15 through PD1, PD2 and PD3. In this embodiment, scan electrode address data (A0, A1, A2, A3, A4, A5, A6,
A7, A8, A9, A10, A11) and video data (D
0, D1, D2, D3, ... D2558, D2559) are transferred through the same transmission line of each of the signal lines PD0 to PD3, so that the scan electrode address data and the video data must be distinguished. In this example, an A / D is provided as a signal for identification, and when this A / D signal is at a high level, it indicates that it is scan electrode address data.
When it is low level, it indicates that it is video data,
Each relationship is defined. Further, the A / D signal also includes meaning as a signal for starting transfer when the display information is transferred.

When the scan electrode address data is applied to the scan electrode drive circuit 12 and the video data is applied to the information electrode drive circuit 13, the scan electrode address data A0 to A11 and the video data D0 to D2559 are provided on the signal lines PD0 to PD3. Since they are arranged serially, scan electrode address data A
A circuit for allocating 0 to A11 and video data D0 to D2559 or a circuit for extracting scan electrode address data A0 to A11 is required. This operation is performed by the control circuit 15. This control circuit 15 causes the signal lines PD0 to PD3
The scan electrode address data A0 to A11 arranged above are extracted, temporarily stored, and output to the scan electrode driving circuit 12 during the horizontal scanning period when driving the designated scan electrode 12C. The scan electrode address data A0 to A11 are input to the decoder 12A in the scan electrode driving circuit 12,
The scan electrode 12C is selected through the decoder 12A.

On the other hand, the video data D0 to D2559 are input to the shift register 13A in the information electrode drive circuit 13 and are shifted every four pixels by the transfer clock CLK to have the number of pixels corresponding to the information electrodes 13D (2560). The video data D0 to D2559 are separated. Shift register 13
When the shift of one scanning line in the horizontal direction is completed at A, the video data D0 to D2559 on the shift register 13A of 2560 times of dew are transferred to the line memory 13B and stored in the horizontal scanning period.

Further, in this embodiment, the drive of the display panel 11 and the scan electrode address data A0 in the main body device 14 are performed.
Since the A11 and the video data D0 to D2559 are generated asynchronously, the control circuit 15 does not operate when the display information is transferred.
It is necessary to establish synchronization between the device and the main body device 14. The signal for this synchronization is the signal Sync, which is generated in the control circuit 15 every horizontal scanning.

The signal Sync performs the operation associated with the A / D. The main body device 14 constantly monitors the Sync signal, and transfers the display information when the Sync signal is at the low level, and conversely when the Sync signal is at the high level, the display information is transferred after the transfer of the display information for one horizontal scanning is completed. Do not do. That is, in FIG. 2, the A / D signal is set to the high level at the moment when the Sync signal becomes the low level, and the control circuit 15 returns the Sync signal to the high level during the display information transfer period. Then, after a lapse of one horizontal scanning time measured from the point A (point B), the low level is restored. If B
When the main body device 14 continuously transfers display information at the point of time, that is, when driving the next scan electrode, the A / D
The signal is set to high level and transfer starts. Since refresh driving is performed in the present embodiment, line-sequential continuous driving is performed.

The predetermined one horizontal scanning time is determined due to the characteristics of the ferroelectric liquid crystal and the driving method, and the desired application time is determined in consideration of various optimum driving conditions. , Which is defined as one horizontal scanning time. In this embodiment, one horizontal scanning time (period) is set to about 80 μsec at room temperature. Therefore, the frame frequency was about 6.5 Hz. The transfer clock CLK is 12 MHz, and the transfer time of the scan electrode address data and the video data is about 54 μsec. The waiting time in FIG. 2 is about 26 μsec. The control signal CNT in FIG. 2 is a control signal for generating a desired drive waveform.
This is the control circuit 15 from each drive circuit 12 and 1
3 is output. The output timing of CNT is the same as the timing of outputting the scan electrode address data A0 to A11 to the scan electrode driving circuit 12, and the shift register 13A
The timing is the same as the timing of transferring the video data of (1) to the line memory 13B.

As shown in FIG. 2, the timing of these CNT signals starts at an arbitrary time within the period C defined between the start of the waiting time and the start of the low level of the Sync signal, and one horizontal scanning period and effective drive control. It is output as a signal. Since refresh driving is performed in this embodiment, a certain time in the period C is also the start (access start), and at the same time is the drive end point of the previous scan electrode.

The above communication is performed between the drive circuits 12 and 13, the control circuit 15 and the main body device 14, and the refresh drive is performed at the drive timing as described above.

Next, the display information generating means which is a characteristic configuration of the present invention will be described.

The display information is generated by the main body device 14, and is generated according to the specifications according to the signal transfer described above. Here, this is referred to as an image forming circuit.

FIG. 3 shows a main program for generating display information in the partial write routine. This operation is shown in FIG. CPU
It is judged whether new rewriting data comes from, and if it does not come, this is repeated, and if it comes, the previous data of VRAM is rewritten and new data is written (VRAM is a memory for storing video data. ). In this way, the image forming circuit adds the scan electrode address data to the video data newly sent from the CPU and controls the control circuit 1.
Transfer to 5.

On the other hand, the full-face refresh drive is executed at regular intervals as described above. For this reason, an interrupt request is sent to the main program so that the entire surface refresh drive is performed, and the image forming circuit executes the routine shown in FIG. 4 at regular intervals in response to the interrupt request. In the operation of FIG. 4, if partial writing is in progress,
This is interrupted and new data from the CPU is rejected. Then, the display information of the entire screen is transferred to the control circuit 15. Then, the time until the next full-face refresh drive is set (1 second in this embodiment). Then, new data from the CPU is accepted.

The operation of the image forming circuit is determined as described above, and the driving method of the present invention is executed.

Next, since the scan electrode address data is an address corresponding to the scan electrode 12C of the display panel 11, it becomes address data unique to the scan electrode. Therefore, in this embodiment, the data in the VRAM managed by the image forming circuit is mapped as shown in FIG. First, it was divided into two regions, one of which was assigned to scan electrode address data and the other of which was assigned to video data. In the scan electrode address data area, one line of corresponding video data is arranged for the pixels of the display panel 11, and the scan electrode address data is arranged at the head of the one-line video data. The details of the data mapping in the VRAM are shown in FIG. The first 16-bit serial data is scan electrode address data, followed by 2
The video data is 560 bits.

As the display information sent to the control circuit 15, the display information for one scanning line is sent in the data format shown in FIG.

Next, the drive signal applied to the display panel 11 will be described.

7 and 8 show drive waveforms used in this embodiment. In FIG. 7, the scan selection signals S _2n-1 (n = 1, 2, 3, ...) Applied to the odd-numbered scan electrodes in the odd frame F _2M-1 and the even frame F _2M (M = 1, 2, 3 ...). ) And the scan selection signal S _2n applied to the even-numbered scan electrodes. According to FIG. 7, the scan selection signal S _2n-1 is an odd frame F _2M-1 and an even frame F _2M (M = 1, 2, 3, ...).
The voltage polarities in the same phase (voltage polarities based on the voltage of the scanning non-selection signal) are opposite to each other, and the scanning selection signal S _2n is also the same. Further, the scan selection signals S _2n-1 and S _2n applied within one frame period have different voltage waveforms, and the voltage polarities of the same phase are opposite to each other.

In the scan drive waveform example of FIG. 7, a third phase is provided for simultaneously suspending the screen (for example, applying a voltage 0 to all the pixels forming the screen simultaneously).
The third phase of the scan selection signal is set to voltage 0 (the same level as the voltage of the scan non-selection signal).

Further, according to FIG. 7, as the information signal applied to the signal electrode in the odd frame F _2M-1 , the scan selection signal S
_{For 2n-1} , a white signal (combined with the scan selection signal S _2n-1) is applied with a voltage 3V ₀ exceeding the threshold voltage of the ferroelectric liquid crystal in the second phase to form a white pixel. ) And a holding signal (the voltage ± V ₀ smaller than the threshold voltage of the ferroelectric liquid crystal is applied to the pixel by combining the scanning selection signal S _2n-1 )
Are selectively applied to the scanning selection signal S _2n , and a voltage -3V ₀ that exceeds the threshold voltage of the ferroelectric liquid crystal in the second phase is generated due to the combination with the black signal (the scanning selection signal S _2n). Applied to form a black pixel) and a holding signal (the voltage ± V ₀ smaller than the ferroelectric liquid crystal is applied to the pixel by combining the scan selection signal S _2n ) are selectively applied.

In the even-numbered frame F _2M following the writing of the odd-numbered frame F _2M-1 , as the information signal to be applied to the signal electrode, the same black signal as that described above is used for the scan selection signal S _2n-1 . The holding signal and the scanning selection signal S are selectively applied.
_{For 2n} , the white signal and the holding signal similar to the above are selectively applied.

FIG. 8 shows a timing chart when the display state shown in FIG. 9 is written by the drive waveform shown in FIG. In FIG. 9, ◯ represents white pixels, and ● represents black pixels. 8 is a time series waveform of the voltage applied to the intersection of the I ₁ -S ₁ scan electrode S ₁ and the signal electrode I ₁ in FIG.
I ₂ -S ₁ is a time series waveform of the voltage applied to the intersection between the scanning electrode S ₁ and the signal electrode I _2.

In addition to the driving method described above, the present invention also discloses German Patent Publication No. 350 of US Pat. No. 4,655,561.
It is also possible to use the driving method disclosed in 1982, German Laid-Open No. 3644220, or the like.

FIG. 10 is a timing chart showing the display operation principle of the present invention. The first frame is a full refresh drive period. At this time, if the rewriting information is generated, the main body device 14 prepares the rewriting display information (scan electrode address data + image data) by the means described above. And from the beginning of the second frame,
The partial write operation starts with the above-mentioned signal transfer means (the signal transfer means is the same regardless of the full refresh drive state and the partial write state). Partial writing is completed,
The entire surface is refreshed again as soon as a fixed time is reached from the first frame.

Here, when the rewriting information does not extend over the entire surface, that is, the partial writing scanning electrode <the number of entire surface scanning electrodes (19
In the case of 20 lines, the entire surface is refresh-driven as soon as the scheduled time comes after the partial writing is completed as shown in FIG.

Next, when the rewriting information covers the entire surface, that is, the number of scanning electrodes for partial writing ≧ the number of scanning electrodes for entire surface (1920
In this case, as shown in FIG. 10B, after the full refresh driving in the first frame, full writing is continued with the frame frequency of full refresh driving until the end.

In this embodiment, the entire refresh drive cycle is set to 1 second.

FIG. 11 shows an example of multi-window screen display. The display screen displays different screens in the display area. Window 1 is a pie chart showing the results of a count. Window 2 is window 1
A screen showing the tabulation result of. Window 3 is a bar graph showing the counting result of window 1. The window 4 operates for writing a sentence. And the background is plain white.

Here, the window 4 is now the work screen, and the other windows are still images. In other words, the window 4 is in a moving image display state while a sentence is being created. Specific operations in this moving image state are scrolling, insertion / deletion of words / phrases, copying, area movement, and the like. These operations require relatively fast operations. An example of display operation will be given below.

First Example-A character is newly added and displayed on an arbitrary line in the window 4. Character font is 16x1
There are 6 configurations. To additionally display one character is to rewrite 16 scan electrodes. The timing for rewriting only 16 scan electrodes during refresh driving is 16 partial write scan electrodes <total scan electrode (1920)
Therefore, the timing is as shown in FIG.
The entire frame is refresh driven in the first frame, and the driving time of 16 scanning electrodes from the beginning of the second frame is 16 × 80 =
Partial writing is performed for 1.28 msec, and 1 second after the first frame is driven, the entire surface is refreshed again. After partial writing, approx. (1000msec-153.6m
sec−1.28 msec).

Second example-window 4 is in a smooth scroll state.

The number of scanning electrodes occupied by the window 4 is 400.
Suppose it is a book. Smooth scroll display is to rewrite 400 lines. The timing of driving the 400 scan electrodes during the refresh driving is the same as in the first example. The entire frame is refresh driven in the first frame, and the driving time of 400 scan electrodes from the beginning of the second frame is 4
00 × 80 μsec = 32 msec is repeatedly written until the next full refresh drive start time comes. At this time, the speed of the smooth scroll is about (1
000msec-153.6msec) / 32msec
= 261ine / sec. Since the general smooth scroll speed is 10 to 301 ines / sec, the smooth scroll speed shown in the second example is never slow.

FIG. 12 schematically shows an example of a ferroelectric liquid crystal cell as the display means of the present invention. Upper and lower electrode substrates (glass substrates) 121 coated with transparent electrodes
A layer 122 composed of molecules of ferroelectric liquid crystal is enclosed between A and 121B so as to be perpendicular to the electrode substrates 121A and 121B. This ferroelectric liquid crystal exhibits a chiral smectic C or H phase, and the film thickness is set to be sufficiently thin (for example, 0.5 μm to 5 μm) to eliminate the inherent helical structure of the chiral smectic phase.

When an electric field E (-E) of a certain threshold value or more is applied between the upper and lower electrode substrates 121A and 121B, the liquid crystal molecules 123 change the orientation direction to the electric field direction. Liquid crystal molecules have an elongated shape and exhibit refractive index anisotropy in the major axis direction and the minor axis direction. Therefore, by disposing crossed Nicols polarizing plates (not shown) above and below the glass surface, a liquid crystal modulation element whose optical characteristics change depending on the applied polarity of the electric field E (-E) is obtained. When an electric field E of a certain threshold value or more is applied to such a cell, the liquid crystal molecules 123 are aligned in the first stable state 123A. When a reverse electric field -E is applied, the liquid crystal molecules 123 are oriented in the second stable state 123B and the orientation of the molecules can be changed. Further, unless the applied electric field E and -E exceed a certain threshold value, they are kept in their respective alignment states.

The ferroelectric liquid crystal element used in this example has a monostable alignment state and has a first stable state 123A.
The second stable state 123B and the second stable state 123B are asymmetric, and after releasing the electric field E or -E, either stable state or another more stable third stable state is oriented.
In the present invention, it is preferable to apply the monostable alignment state to a ferroelectric liquid crystal device, but US Pat.
No. 67,924 discloses a ferroelectric liquid crystal device having an alignment state which exhibits semi-permanent or permanent bistability, and an alignment state having a helical structure as disclosed in European Patent No. 91661. It can also be applied to ferroelectric liquid crystal elements.

FIGS. 13A and 13B show an embodiment of the liquid crystal element of the present invention. FIG. 13A is a plan view of the liquid crystal element of the present invention, and FIG.
It is an A'cross section figure.

A cell structure 130 shown in FIG. 13 is a pair of substrates 131A made of a glass plate or a plastic plate.
And 131B are held at predetermined intervals by spacers 134,
The cell structure has a structure in which an adhesive 136 is adhered to seal the pair of substrates. Further, an electrode group including a plurality of transparent electrodes 132A is provided on the substrate 131A (for example, a scanning voltage of a matrix electrode structure). (Applying electrode group)
Are formed in a predetermined pattern such as a strip pattern. On the substrate 131B, an electrode group (for example, a signal voltage applying electrode group in the matrix electrode structure) including a plurality of transparent electrodes 132B intersecting the above-mentioned transparent electrode 132A is formed.

Substrate 1 provided with such a transparent electrode 132B
31B includes, for example, inorganic insulating substances such as silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, Polyamide imide, polyester imide, polyparaxylelin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride,
It is possible to provide the orientation control film 135 formed by using an organic insulating material such as polyamide, polystyrene, cellulose resin, melamine resin, urea resin or acrylic resin.

The orientation control film 135 is obtained by forming a film of the above-described inorganic insulating material or organic insulating material and then rubbing the surface in one direction with velvet, cloth or paper.

In another preferred embodiment of the invention, SiO
The alignment control film 135 can be obtained by forming a film of an inorganic insulating material such as SiO ₂ or SiO ₂ on the substrate 131B by the oblique vapor deposition method.

In another embodiment, the surface of the substrate 131B made of glass or plastic or the substrate 131B.
After the above-mentioned inorganic insulating material or organic insulating material is formed as a film on the surface of the film, the surface of the film is etched by the oblique etching method, whereby the orientation control effect can be imparted to the surface.

It is preferable that the above-mentioned orientation control film 135 also functions as an insulating film at the same time. For this reason, the thickness of the orientation control film 135 is generally set in the range of 100Å to 1 μ, preferably 500Å to 5000Å. You can This insulating film also has an advantage of being able to prevent the generation of a current generated due to impurities or the like contained in the liquid crystal layer 133 in a minute amount, and therefore does not deteriorate the liquid crystal compound even if the operation is repeated.

Further, in the liquid crystal element of the present invention, the same material as the above-mentioned alignment control film 135 can be provided on the other substrate 131A.

As the ferroelectric liquid crystal 133, there are US Pat. No. 4,561,726 and US Pat. No. 4,614,6.
09, US Pat. No. 4,589,996, US Pat. No. 4,592,858, US Pat.
A liquid crystal compound or composition exhibiting a chiral smectic phase disclosed in, for example, 96,667 and U.S. Pat. No. 4,613,209 can be used.

In the figure, reference numerals 133 and 138 denote polarizing plates, the polarization axes of which cross each other, preferably at 90 °. According to the present embodiment, it is possible to speed up partial moving image display at a low frame frequency while stably displaying a still image of a ferroelectric liquid crystal material having a strong tendency toward monostability.

[0059]

As described above, the display means is driven and
By controlling, it is possible to realize both partial write (rewrite) drive and full refresh drive, and since one horizontal scanning drive time does not relate to the number of scanning electrodes, a drive voltage for image formation, optical It does not reach the electro-optical characteristics such as the response characteristics, and in principle, it is possible to form an image without limiting the number of scanning electrodes of the display panel.

[Brief description of drawings]

FIG. 1 is a block diagram of a display device of the present invention.

FIG. 2 is a chart showing the timing of signal transfer and driving used in the display device of the present invention.

FIG. 3 is a sequence diagram showing a partial write routine.

FIG. 4 is a sequence diagram showing a full refresh drive routine.

FIG. 5 is an explanatory diagram showing VRAM data mapping.

FIG. 6 is an explanatory diagram showing a data format of display data for one scanning line.

FIG. 7 is a waveform diagram of drive waveforms used in the present invention.

FIG. 8 is a diagram showing a timing chart.

FIG. 9 is an explanatory diagram showing a display state of pixels.

FIG. 10 is a timing chart in the case of the number of scanning electrodes for partial writing <the number of scanning electrodes for the entire surface and the number of scanning electrodes for partial writing ≧ the number of scanning electrodes for the entire surface.

FIG. 11 is a display screen diagram showing an example of image display used in the present invention.

FIG. 12 is a perspective view for schematically explaining a ferroelectric liquid crystal element used in the present invention.

FIG. 13 is a plan view of an element used in the present invention and its AA ′.
It is a figure which shows a cross section.

Claims (1)

[Claims] 1. A display control device for forming a display image on a display means in which a plurality of scan electrodes and a plurality of information electrodes are arranged in a matrix, wherein the plurality of scan electrodes are sequentially selected and the plurality of information are displayed. A memory for storing information displayed by refresh driving means for repeatedly applying the signal to the electrodes; a means for changing the information stored in the memory; and a display area of the display means based on the change of the information. 2. A display control device comprising: an address signal for selecting only a part of the scan electrodes and a means for generating an image information signal for rewriting a display image of the part.