JP3234081B2 - Information transmission device and method of driving the information transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention generally relates to information transmission.
The present invention relates to a device and a driving method of the information transmission device , and more particularly to a device for displaying a halftone by frame modulation.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal compound is filled between a scanning electrode group and an information electrode group constituting a matrix electrode, and a large number of pixels are formed at intersections of the scanning electrode group and the information electrode group. Liquid crystal display elements for displaying image information are well known. Above all, a ferroelectric liquid crystal display device having bistability and quick response to an electric field is expected as a high-speed and storage-type display device. For example, JP-A-61-90
No. 23 and the like include two glass substrates on which a transparent electrode is formed and subjected to an alignment treatment, and these glass substrates are arranged to face each other so as to maintain a cell gap of about 1 to 3 μm. And a liquid crystal display device in which a ferroelectric liquid crystal is injected between these glass substrates. In addition, a number of driving methods for matrix driving have been proposed so far. For example, US Pat. No. 4,655,561, US Pat.
No. 4,800,382; U.S. Pat.
No. 656, U.S. Pat. No. 4,932,759, U.S. Pat.
Practical driving devices are disclosed in specifications such as 938574 and U.S. Pat. No. 5,058,994.

As a method of displaying a halftone in such a liquid crystal display device, a frame modulation method (time modulation method, frame thinning method) is known. This method is disclosed in JP-A-61-69036 and JP-A-62
-56936, JP-A-64-61180,
JP-A-5-127623 and European Patent Publication No. 319291 disclose a pixel which does not have a gradation display function and displays only two states.
By changing the ratio of the display time in these two states, pseudo gradation display is performed.

[0004]

In the above-mentioned frame modulation method, one frame is formed by scanning all the scanning electrodes the same number of times, so that it takes a long time to display and the frame frequency decreases. There is a problem that flicker occurs. In order to prevent such flicker, it was necessary to limit the number of scanning electrodes.

Further, since one frame is formed by scanning all the scanning electrodes the same number of times, the rewriting cycle cannot be changed even if the display content is changed, and therefore a quick response cannot be made. was there. That is, in an OA device such as a computer or a workstation, the intention of the operator must be promptly reflected on the CPU, and the response of moving display of a pointing device such as a mouse needs to be enhanced.

Accordingly, the present invention divides one frame into a full-screen scanning period and a partial rewriting period, and scans only the scanning electrodes whose display contents are changed in the partial rewriting period, thereby preventing flicker. Information transmission device that performs excellent halftone display and enhances the response of moving display such as a pointing device , and the like.
An object of the present invention is to provide a method for driving a notification transmission device .

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a pair of substrates arranged so as to face each other, and an intersection formed on each of the pair of substrates. at a number of scan electrode groups to form a pixel and the information electrode group, an information transmission device and a liquid crystal sandwiched between the pair of substrates to change the scale of the display time within one frame In the method for driving an information transmission device that performs halftone display, the one frame includes a full-screen scanning period in which scanning of all scanning electrodes is performed, and a portion in which scanning is performed only on scanning electrodes whose display contents are changed. consists of a rewriting period, have rows rewriting partially visible in a period shorter than a frame period, and the
In the partial rewriting period, when n is a positive number, 2
The display is performed with ⁿ gradations .

[0008]

[0009]

[0010]

[0011]

In this case, it is preferable that equal gradation display is performed in the full screen scanning period and the partial rewriting period.

It is preferable that interlaced scanning be performed during the entire screen scanning period.

Still further, it is preferable that the liquid crystal is a ferroelectric liquid crystal.

Meanwhile, the information transmission device according to the present invention, another
A pair of substrates arranged so as to face each other,
Are arranged on the substrate of
A scanning electrode group and an information electrode group for forming, and the pair
A liquid crystal display device consisting of liquid crystal sandwiched between substrates
Information transmission device that displays halftones
In addition, one frame period is divided into a plurality of frames having the same display period.
Divided into blocks of
In multiple partial scan blocks, pixels that have changed in the image
Performs partial rewrite scan to scan and select only the corresponding scan electrodes
All in the whole scan block other than the partial scan block
Scan signal control to perform full screen scan to select scan electrodes
Control circuit, one frame period during the entire screen scanning period
A plurality of selective scans including a first selective scan and a second selective scan within
The inspection is performed for each scan electrode, and the first selection for each scan electrode is performed.
During the one frame period from the selective scanning to the second selective scanning.
One interval ratio is set, and during the partial rewriting scanning period,
The first selection scan and the second selection scan within one block period.
Perform multiple selective scans on each scan electrode, including the same scan
One block from the first selection scan to the second selection scan on the electrode
Set the second interval ratio within the scanning period and scan the entire screen
And the number of displayable gradations in partial rewrite scanning
Set the first interval ratio and the second interval ratio equal
It is characterized by the following.

[0016]

According to the above construction, the one frame includes a full-screen scanning period for scanning all the scanning electrodes and a partial rewriting period for scanning only the scanning electrodes whose display contents are changed. When there is a change, the display of the changed scan electrode can be partially rewritten in a cycle shorter than the frame cycle.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIG.
9 will be described with reference to FIG.

As shown in FIG. 1, the liquid crystal display element 1 according to the present embodiment includes a pair of glass substrates 2 and 3 which are arranged to face each other with a predetermined gap. A large number of scanning electrodes 5,... And information electrodes 6,. These electrodes 5, ..., 6, ...
As shown in detail in FIG. 2, it has a band shape, and a large number of pixels (for example, indicated by reference numeral 7) are formed at intersections of the electrodes 5,. An insulating film 9 is formed so as to cover these electrodes 5,..., 6, and an alignment film 10 is further formed.
The gap between the substrates is closed by a sealing material 11, and the gap is filled with a ferroelectric liquid crystal 12.
Further, an analyzer 13 and a polarizer 15 are arranged at positions facing the two substrates 2 and 3, respectively, and these are arranged in crossed Nicols.

Next, peripheral devices of the above-described liquid crystal display element 1 will be described with reference to FIG.

A scanning signal application circuit 402 and an information signal application circuit 403 are connected to the liquid crystal display element 1 according to the present embodiment, and these circuits 402 and 403 are connected to a scanning signal control circuit 404 and an information signal control circuit. 406, a drive control circuit 405, and a graphic controller 407 are sequentially connected. Then, the data and the scanning method signal are transmitted from the graphic controller 407 to the scanning signal control circuit 404 and the information signal control circuit 406 via the drive control circuit 405. These data are converted into address data and display data by these circuits 404 and 406, and the other scanning method signal is sent to the scanning signal applying circuit 402 and the information signal applying circuit 403 as they are. ing. Further, the scanning signal application circuit 402 is configured to generate a scanning signal A (see FIG. 4) in accordance with the address data and apply the signal A to the scanning electrodes 5,. Further, the information signal application circuit 403 is configured to generate an information signal B or C according to the display data and apply either signal to the information electrodes 6,.

Next, regarding these signals A, B and C,
Description will be made with reference to FIG.

The scanning signal A comprises a reset pulse A1, a selection pulse A2 and an auxiliary pulse A3. The information signal B is a bright information signal and the other information signal C is a dark information signal. The amplitude of the reset pulse A1 is V1, the amplitude of the selection pulse A2 is V2, the amplitude of the auxiliary pulse A3 is V3, and the amplitudes of the information signals B and C are V4 and V5. Then, the reset pulse A1 of the scanning signal A brings all the pixels on the selected scanning electrode into a dark state, and these pixels display information (bright display or dark display) → reset by the reset pulse A1 (dark state) → The display contents are switched in the order of displaying information (bright display or dark display). FIG. 5 (a) shows an example of such a case. Curve D shows a state of bright display → dark state → bright display, and curve E shows dark display →
This shows a state where a dark state is changed to a dark display. In this figure, the horizontal axis represents time, and the vertical axis represents the amount of transmitted light.

In the period indicated by reference numeral F in this figure, that is, a period in which a part of the reset period and a part of the selection period are added, display in a strict sense is not performed. Are excluded from this period F. However, when the period from the scanning selection to the next scanning selection is sufficiently longer than the reset period, there is substantially no problem even if this is set as the display period. Further, this period F is substantially equal to 1H using the drive signal of FIG. FIG.
(b) shows the driving waveform applied when the pixel display changes as shown by a curve D, and FIG. 2 (c) shows the driving waveform applied when the pixel display changes as a curve E. Is shown. Also, reference numerals 301, 302,
303 is a reset pulse, a selection pulse, and an auxiliary pulse, respectively.

Next, taking a liquid crystal display device having 320 × 200 pixels as an example, the scan selection timing will be described with reference to FIG. Here, the vertical axis (y-axis) takes the address of the scanning electrode, the horizontal axis (t-axis) takes time, and one vertical scanning period (1H) is used as a unit.

In this embodiment, 60 frames are included in one frame.
Zero scanning selection is performed (600H),
One frame is divided into six blocks ( first to sixth ), and four blocks ( first, third, fourth and sixth ) (entire scanning block)
Is a full-screen scanning period, and the remaining two blocks, the second and fifth (partial scanning blocks), are a partial rewriting scanning period. Therefore, during the entire screen scanning period, 40
Zero (400H) full screen scanning is performed, and 200 (200H) partial rewriting scans are performed during the partial rewriting scanning period. In the present embodiment, six blocks are equal display time, partial scan
The blocks are set so as not to be continuous with each other. Hereinafter, each of the full screen scanning period and the partial rewriting scanning period will be described.

In the entire screen scanning period, scanning is performed twice (a total of 400 times) for 200 scanning addresses regardless of whether or not display contents are changed. Specifically, scan addresses 0 to 99 are upper, and 100 to 199 are lower.
, The first scan of the upper in the first block (first selective scan), the second scan of the upper in the third block (second selective scan), and the first scan of the lower in the fourth block. (First selection scan), and a lower second scan (second selection scan) is performed in the sixth block. Then, by performing scanning at such timing, the ratio between the display periods G and H (first interval ratio) becomes 1: 2 at all addresses. Therefore, as shown in Table 1, four gradations are displayed by a combination of dark display / bright display in these periods G and H. Then, the luminance shown in FIG. 7 is obtained with these four gradations (bright display is set to 100% and dark display is set to 0%). In order to calculate the ratio between the display periods G and H, it is necessary to consider the reset period. However, the reset period is 1/200 of the entire period (the period from the scan selection to the next scan selection). Or 1
Since it is / 400, it can be ignored.

[0028]

[Table 1] In one partial rewriting scanning period, as shown in FIG. 6, 200 blocks of scanning selection are performed in two blocks, and 100 blocks of scanning selection are performed in each block. Each block is further divided into five sets. ing. Then, in each set, as shown in FIG. 8, four arbitrary scanning addresses whose display contents are changed are selected, and 20 times (20H)
Scan selection is performed. Therefore, in one block, partial rewriting is performed for 20 scanning line addresses. FIG. 8 shows a case where four scan addresses Y0 to Y3 in one set have 20 scan addresses.
This indicates the timing of performing the scan selection twice, and the symbol “●” in the figure indicates the period of the dark state due to the scan selection. In each scanning address, display periods I and J having a ratio of 1: 2 are provided twice each in order to clarify the gradation. Then, the display period I
By setting the ratio (second interval ratio) between J and J to 1: 2, four gradations are displayed by a combination of dark display / bright display in these periods I and J (see Table 2). ). In addition, with these four gradations, FIG.
(Bright display is 100%, dark display is 0%)
And). It should be noted that, in claim 10 of the claims, “the first selective scanning in the partial rewriting scanning period” means the selective scanning that triggered the start of the J period in FIG.
The “second selective scanning in the partial rewriting scanning period” refers to FIG.
Means the selective scanning that triggered the start of the I period.

As described above, in this embodiment, four gradations are displayed both in scanning the entire screen and in scanning partial rewriting.

[0030]

[Table 2] Hereinafter, effects of the present embodiment will be described.

In this embodiment, four gradations are displayed for both full-screen scanning and partial rewriting scanning, and the same gradation and luminance are maintained, so that the operator can determine which gradation is being displayed. Becomes easier. Also, it is possible to prevent the occurrence of flicker due to a difference in gradation balance.

In this embodiment, the second and fifth blocks are used as the partial rewriting scanning periods, and the full-screen scanning period and the partial rewriting scanning periods are provided alternately. Therefore, when the display content changes, the image quality is less reduced than in the case where the full-screen scanning is stopped and partial rewriting is performed, and a good halftone can be obtained. In addition, since the partial rewriting scanning periods are provided evenly in one frame, a response to a change in display content can be increased.

Further, since the ratio of the frame modulation in this embodiment is 2 ⁿ (n is a positive integer), the image quality is good and the data processing is preferable.

Further, in this embodiment, since the period of the partial rewriting is shorter than the driving method using only the full screen scanning, the response of the moving display of the pointing device or the like can be improved. Further, since the balance between the full-screen scanning period and the partial rewriting scanning period is appropriate and no gap is provided in the scanning selection, the scanning cycle does not become slow, and the frame frequency does not decrease and flicker does not occur.

The inventor conducted an experiment for confirming the effect of the present embodiment. The liquid crystal display element used in the experiment is assumed to be filled with liquid crystal having the physical properties shown in Table 3, and the signals shown in FIG. 4 are obtained by V1 = 20V V2 = -14V V3 = 6.6V V4 = 6V V5 = −6V ΔT = Although 25 μs 1H = 50 μs, good halftone display was obtained. At this time, the frame frequency was about 33 Hz, and the partially rewritable frequency was about 67 Hz. No flicker occurred and the mouse response was good.

[0036]

[Table 3] When there is no change in the display content, it is not necessary to perform partial rewriting originally, but it is desirable not to shorten the partial rewriting period in order to maintain gradation. Further, in order to maintain the contrast, it is better to keep applying the same waveform as the information signal. Furthermore, three color filters may be arranged in the liquid crystal display element according to the above-described embodiment, and three pixels may be used to perform multi-color display.

Next, another example of the present invention will be described with reference to FIG.

FIG. 10 shows the relationship (scanning chart) between the scanning address and the application timing of the scanning signal. It is assumed that the display element in this example has 640 × 400 pixels. Further, four gradations are displayed at the time of full screen scanning and partial rewriting scanning. Note that interlaced scanning is performed in full-screen scanning.

In FIG. 10, the y-axis represents the address of the scanning electrode, and the t-axis is 1H on the time axis. 1200 scanning selections are made in one frame (1200H),
Of these, 800 times (800H) are used for full screen scanning, and 400 times (400H) are used for partial rewriting scanning. First,
One frame is divided into 12 blocks, and the first, second,
Blocks 4, 5, 7, 8, 10, and 11 are a full screen scanning period, and blocks 3, 6, 9, and 12 are a partial rewriting scanning period. The full-screen scanning period is a period in which halftones are displayed by scanning 400 scanning addresses twice over one frame, regardless of whether or not the display contents are changed.
On the other hand, the partial rewriting scanning period is a period in which an arbitrary scanning address having a change in display content can be selected, and is set such that 100 scanning selections can be performed four times in one frame.

In the case of full-screen scanning, the scanning addresses 0 to 9
9 is upper1, 100-199 is upper2, 200-299
Is lower1 and 300-399 are lower2, the first block of the upper1 even address and the lower1 odd address in the first block.
Scans, upper2 odd address and lower2 in second block
1st scan of even address, 1st scan of upper1 odd address and lower1 even address in 4th block, 5th scan
The second scan of the upper1 even address and the lower1 odd address in the block, the upper2 even address and lo in the seventh block
wer2 1st scan of odd address, uppe in 8th block
r1 odd address and lower1 even address second scan,
The 10th block performs the second scan of the upper 2 odd address and the lower 2 even address, and the 11th block performs the second scan of the upper 2 even address and the lower 2 odd address by interlacing. Scanning is performed at such a timing, so that the display periods K and L at all the addresses are obtained.
Is 1: 2. In the figure, even addresses are represented by solid lines, and odd addresses are represented by dotted lines. Further, since the ratio of the reset period to the period from the scan selection to the next scan selection is 1: 400 or 1: 800,
The reset period can be ignored. Furthermore, the third, sixth, ninth,
In the partial rewriting scanning period of two blocks, the same control as in the above embodiment is performed. Therefore, also in this example, four gradations are displayed by a combination of dark display / bright display, and the same effect as in the above-described embodiment can be obtained.

The inventor conducted an experiment to confirm the effect. In the experiment, V1 = 25V V2 = −17V V3 = 7.7V V4 = 7V V5 = −7V ΔT = 20 μs 1H = 40 μs for each signal shown in FIG. Obtained. At this time, the frame frequency was about 20 Hz, and the partial rewritable frequency was about 80 Hz. No flicker occurred and the mouse response was good.

[0042]

As described above, according to the present invention,
One frame is divided into a full-screen scanning period and a partial rewriting period. In the partial rewriting period, only the scanning electrodes whose display contents are changed are scanned, so that the scanning is partially performed in a cycle shorter than the frame cycle. The display can be rewritten. Therefore, when the display content changes, the image quality is less reduced than in the case where the full-screen scanning is stopped and partial rewriting is performed, and a good halftone can be obtained. Further, a response to a change in display content can be increased.

On the other hand, by performing equal gradation display in the full screen scanning period and the partial rewriting period, the operator can easily determine which gradation is being displayed. Also, it is possible to prevent the occurrence of flicker due to the difference in gradation.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a liquid crystal display element used in this embodiment.

FIG. 2 is a plan view showing a structure of a liquid crystal display element used in the present embodiment.

FIG. 3 is a block diagram illustrating peripheral devices of a liquid crystal display element.

FIG. 4 is a waveform diagram of a scanning signal A and information signals B and C.

5A is a diagram showing a change in the amount of transmitted light in a pixel, and FIGS. 5B and 5C are diagrams showing an example of a drive signal. FIG.

FIG. 6 is a chart showing a relationship between a scan address and a timing at which a scan signal is applied.

FIG. 7 is a diagram for explaining the relationship between pixel gradation and luminance.

FIG. 8 shows four scan addresses Y0 in one set.
FIG. 9 is a chart showing timings at which 20 scan selections are made for Y3.

FIG. 9 is a diagram for explaining the relationship between pixel gradation and luminance.

FIG. 10 is a chart showing a relationship between a scan address and a timing at which a scan signal is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2, 3 Substrate (glass substrate) 5, ... Scan electrode 6, ... Information electrode 12 Liquid crystal (ferroelectric liquid crystal) 404 Scan signal control circuit 406 Information signal control circuit 407 Graphic controller

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-73618 (JP, A) JP-A-69320 (JP, A) JP-A-1-140198 (JP, A) JP-A-4- 37893 (JP, A) JP-A-4-134419 (JP, A) JP-A-5-45620 (JP, A) JP-A-5-119298 (JP, A) (58) Fields investigated (Int. ^7, DB name) G09G 3/36 G02F 1/133 560 G02F 1/133 575

Claims (5)

(57) [Claims] 1. A pair of a pair arranged to face each other.
And a substrate and the
Scan electrode group and information electrode forming a large number of pixels at the difference part
And a liquid crystal sandwiched between the pair of substrates.Was
An information transmission device,Display time within one frame
Halftone display by changing the ratio of
WasDriving method of information transmission deviceIn the above, the one frame may be a full screen scan for scanning all scan electrodes.
Scan only for the scanning electrodes whose period and display contents change
The display is partially rewritten in a cycle shorter than the frame cycle.
RowAnd When n is a positive number during the partial rewriting period
To 2 ⁿ Display gradation, A method for driving an information transmission device, comprising: 2. The full-screen scanning period and the partial rewriting.
2. The driving of the information transmission device according to claim 1 , wherein equal gradation display is performed during the receiving period.
Method. (3)Interlaced during full screen scanning
Scanning, The information transmission device according to claim 1 or 2, wherein
Drive method. (4)The liquid crystal is a ferroelectric liquid crystal, The method according to any one of claims 1 to 3, wherein
Driving method of the information transmission device. 5. A pair of substrates arranged so as to face each other, a scanning electrode group and an information electrode group arranged on the pair of substrates and forming a large number of pixels at intersections, and In an information transmission device including a liquid crystal display element made of liquid crystal sandwiched between a pair of substrates and performing halftone display, one frame period is divided into a plurality of blocks having a uniform display period.
Divided into click, a plurality of non-contiguous with each other among the block
In the partial scanning block , partial rewriting scanning is performed to select only the scanning electrodes corresponding to the pixels whose image is changed, and the partial scanning is performed.
A scanning signal control circuit for performing full screen scanning for scanning and selecting all the scanning electrodes in the entire scanning block other than the scanning block, and performing the first selection scanning and the second selection scanning within one frame period during the entire screen scanning A plurality of selective scans, including the first selective scan on each of the scan electrodes.
A first interval ratio is set within one frame period up to the selection scan, and a plurality of selection scans including the first selection scan and the second selection scan are performed on each scan electrode within the one block period during the partial rewrite scan period. From the first selective scan to the same scan electrode.
A second interval ratio within one block period up to the selective scanning is set, and the first interval ratio and the second interval ratio are determined to be equal in order to equalize the number of displayable gradations in full screen scanning and partial rewriting scanning. An information transmission device characterized by the above-mentioned.