JPH0561436A - Driving method for display device - Google Patents

Abstract

PURPOSE:To prevent the double print of a moving image(for example, cursor move) and that of a contour, etc., from occurring in the driving method of a display device which performs memory display. CONSTITUTION:A display period where the rewrite of display data for the display element of a line at every line sequentially is performed, and a display interruption period where erasure operations for all the display elements of the line at every line are performed are set in each frame period, or, the display period and the display interruption period are set alternately at every frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying a memory, and more particularly to a method for driving a panel display device such as an AC plasma display, a DC memory plasma display, and an active matrix LCD (TFT).

[0002]

2. Description of the Related Art FIG. 6 illustrates a basic structure of an AC type plasma display as a prior art.
The discharge cells C are arranged in a matrix in the vertical electrodes X _{1 to} Xm and the horizontal electrodes Y _{1 to} Ym for generating a discharge in the discharge cells C, respectively. A high voltage output having a drive waveform as shown in FIG. 7 described later is applied from the driver IC 4. Reference numeral 1 is a power supply circuit for the driver ICs 3 and 4, and 2 is a control circuit for the driver ICs 3 and 4, and the control circuit 2 includes horizontal and vertical synchronization signals and display data (which discharge cell for each line). Interface data), which includes the data (e.g., which data is to be emitted for display), and which data of which discharge cell is selectively displayed for emission is aligned to the electrodes of which line by aligning the externally input data. Control of whether to output (control of display data and scan) is performed.

FIG. 7 exemplifies each drive waveform in the apparatus of FIG. 6 in a timing chart. One drive cycle (1
The drive waveforms within the horizontal synchronization period) are shown. Then, FIG. 7A shows that a vertical electrode (X
7B shows a drive waveform for one drive cycle in the vertical electrode waveform applied to the vertical electrode waveform. FIG. 7B shows the display data of the display data for a certain horizontal electrode (in this case, a discharge cell) from the horizontal electrode driver 4. This means a line to be rewritten (in this case, the display data is sequentially rewritten for each line, and this is referred to as Yn). One drive cycle (display for that line) in the horizontal electrode waveform applied to the line. A driving waveform corresponding to a driving cycle in which data is rewritten is shown.

As shown in FIG. 7, the drive waveform is divided into an address period and a sustain discharge period. In the address period, the discharge of a corresponding row (line) is caused by the write voltage applied by the vertical electrodes and the horizontal electrodes. Writing corresponding to the display data is performed on the cell (in other words, whether or not writing is performed on each discharge cell on the corresponding line is determined according to the display data).

That is, in the driving cycle in which the display data for the line is rewritten, first, the narrow erase pulse EP shown in the horizontal electrode waveform Yn (FIG. 7B) of the line causes the previous frame to be changed. Erase discharge for forcibly ending the sustain discharge is performed (that is, all the discharge cells of the line that were emitting light in the previous frame are once extinguished), and then the write pulse WP is applied to the line (MP is a sustain described later). Is a pulse).
At this time, a certain vertical electrode waveform Xn (FIG. 7 (A))
To the write cancel pulse WC corresponding to the display data
Is not being output (that is, WC is off) or is being output (that is, WC is on),
It is determined whether writing is performed (that is, discharge light emission is performed) or writing is not performed (that is, erased) in the discharge cell C located at the intersection of the line (horizontal electrode) Yn and the vertical electrode Xn.

The MP shown in the vertical electrode waveform Xn and the horizontal electrode waveform Yn is a sustain pulse, and is applied to each electrode when the discharge cell C is written as described above. Discharge by the sustain pulse MP (in the driving cycle in which the display data is not rewritten to the line, the horizontal electrode waveform Yn of the line has no address period, and only the sustain pulse MP is applied in a predetermined cycle). The state is maintained (that is, the discharge state is maintained unless data is rewritten in the address period in the corresponding line of the next time (next frame)). On the other hand, if the discharge cell C is not written as described above, the sustain discharge is not performed even if the sustain pulse MP is applied thereafter (that is, the data is rewritten in the address period in the next applicable line). Does not occur unless is done). The vertical electrode waveform Xn has an address period for each driving cycle, and at this time, the write cancel pulse W
Whether C is not output or not determines whether or not data is written in each discharge cell in the line Yn that is being rewritten at that time.

FIG. 7C shows a cell voltage waveform (Yn-Xn) when the display data is written in the corresponding cell in the above driving cycle (that is, when the write cancel pulse WC is off), and FIG. (C ') shows the cell voltage waveform (Yn-Xn) when the display data is not written in the corresponding cell (that is, when the write cancel pulse WC is on).

That is, in the case of FIG. 7C, since the pulse WC is turned off, the discharge is caused by applying the write pulse WP, and then the dielectric is formed on the electrode of the discharge cell. Electric charges (wall charges) are accumulated through the layer (that is, on the surface of the dielectric layer) (that is, at the time T of FIG. 7C, the discharge start voltage is exceeded and a writing discharge is generated in the cell to form wall charges. ). As a result, when the sustain pulse MP is applied next, the sustain voltage (voltage of the sustain pulse) applied from the driver IC 3 or 4 and the potential due to the wall charge are added inside the cell,
As the effective voltage exceeds the discharge start voltage (that is, the voltage corresponds to the write pulse WP), discharge occurs. By applying the sustain pulse MP while reversing the polarity, the discharge is sustained, the light emission is repeated, and the total luminance becomes large. Then, this sustain discharge (discharge by sustain pulse) is continued unless the display data is rewritten in the address period in the next line (next frame) as described above.

On the other hand, in the case of FIG. 7 (C '), since the pulse WC is turned on, the effective voltage of the cell is (WP-WC) at the time point T of FIG. 7 (C'). (Fig. 7
(Shown as NWP in (C ')) and the voltage required for writing is not reached, and writing to the cell is not performed.
Therefore, even if the sustain pulse MP is applied thereafter, as described above, there is no sustain discharge by the sustain pulse, and unless the display data is rewritten in the address period in the corresponding line of the next time (next frame), No discharge occurs in the cell.

In FIG. 7, the sustain discharge in the previous frame is forcibly terminated once by the erase pulse EP in the address period of the drive cycle in which the display data is rewritten for each line, and then in the current frame. Although the drive waveform is shown so that the display data is written only in the necessary discharge cells in the relevant line to cause the discharge in the relevant cells, instead, it is displayed in all the discharge cells in the relevant line in the above address period. It is also possible to write data and then erase the necessary discharge cells in the line in the current frame (see FIG. 10 described later).

As described above, the panel scan is CR
Unlike T, which displays electrons by hitting electrons point by point from left to right and from top to bottom (dot sequential scanning), the dots in one line are displayed simultaneously (in the case of FIG. 7 above). Is a line-sequential scan in which write cancel pulse WC is turned off or turned on) and the operation is repeated from the upper line to the lower line.

FIG. 8 is a panel drive timing chart as a conventional example for the apparatus of FIG. 6 described above. The scan lines shown in the figure are one frame period (1 The driving cycle in which data is rewritten to the discharge cells of each line (that is, the driving cycle having the address period) is repeatedly moved sequentially from the upper line to the lower line with the lapse of time every vertical synchronization period). It shows the relationship going on. Further, in FIG. 8 described above, the image displayed on the first line in the first frame (even when all the discharge cells on the first line are lit, only the discharge cells connected to a predetermined vertical electrode are lit up. May be displayed), but is displayed by moving to the second line in the second frame. That is, the discharge cells that were lit in the first line in the first frame were rewritten in the second frame, so that the discharge cells in the first line (the discharge cells lit in the first frame) Is turned off in the second frame, and immediately after that, in the second frame (that is, when time t has elapsed after turning off the discharge cell in the first line), the corresponding discharge cell in the second line (as described above) Shows the case where all the discharge cells of the second line or the discharge cells connected to a predetermined vertical electrode among them are lit.

In this way, unless gradation display (shown in FIG. 9 described later) controlled by the ratio of the display time within a frame is performed, the data once written is rewritten in the next frame. Continue to display until. In the AC plasma display, the time within the frame is effectively used and the sustain discharge is repeated to improve the total brightness.

Further, in the case of gradation display, as shown in the driving timing chart of FIG. 9, the time within a frame is divided into several periods (subfields) having different display times, and the combination thereof is used to control the luminance. The difference (gradation) is displayed.
That is, in the example shown in FIG. 9, the frame (one vertical synchronization period) is divided into three subfields 1, 2, and 3, and the time ratio of the subfields 1, 2, and 3 is 1: 2. : 4 and select any sub-field to turn on as shown in FIG. 9 (that is, for each line (lines 1 to 480 in this case), along each scan line 1, 2, and 3) The first drive cycle that moves with time becomes a drive cycle for rewriting data (that is, with an address period) for each line, so that the discharge cells of each line have eight stages of 0 to 7. The brightness can be selected. When the time ratio of each sub-field is set as described above, the discharge cells of each line are weighted along the scan lines 1, 2, and 3 (the above-mentioned 8 gray scales). In this case, the display data (weighted 1: 2: 4) is written in the drive cycle for rewriting.

FIG. 10 shows a timing chart of input data and n-line drive waveform as another conventional example.
As described above, during the above address period, the display data is once written in all the discharge cells in the line,
Next, a case is shown in which, in the present frame, the discharge cells to be turned on are removed and the other discharge cells are extinguished. That is, for each drive cycle shown in FIG. 10A (for example, about 40 μs in one horizontal synchronization period),
As shown in FIG. 10B, data for each line (data to be supplied to each vertical electrode, in this case, FIG. 10C)
Erase cancel data (erase cancel pulse) EC) for canceling the narrow erase pulse EP shown in FIG. That is, for example, FIG. 10 (B)
The n-th line data shown in (1) indicates, as data for each discharge cell on the n-th line, in which vertical line the data EC is inserted (when the data EC is inserted, the erase pulse EP is When the corresponding discharge cell is canceled and the corresponding discharge cell is lit, the sustain discharge is maintained until the data is rewritten thereafter. On the other hand, when the data EC is not input, the erase pulse EP becomes valid and the corresponding discharge cell is activated. Is turned off and no sustain discharge is performed until the data is rewritten thereafter).

The n-line drive waveform shown in FIG. 10C is a horizontal electrode waveform corresponding to FIG. 7B, and the drive cycle at the center of FIG. This is a drive cycle for rewriting data for a line.
Here, in the example shown in FIG. 10C, unlike the case of FIG. 7, as described above, the write pulse WP is once applied to all the discharge cells for the n line to perform writing, and then the fine pulse is applied. When the width erase pulse EP is applied, whether or not writing is performed is determined depending on whether or not the erase cancel data (erase cancel pulse) EC from the vertical line side is applied, and the data EC is applied. The discharge cells that have not been discharged will be extinguished. MP shown in FIG. 10 (C) is the above-mentioned discharge sustaining pulse. Note that, for example, the n-th line data shown in FIG. 10B is transferred to the vertical electrode driver, then latched once, and delayed by one driving cycle,
It is controlled whether or not to cancel the erase pulse EP in the drive waveform shown in FIG. In this way, in the drive cycle of the central portion in FIG. 10C, the display of the nth line (in other words, data rewriting for each discharge cell of the nth line) is performed, and the light is turned on during the nth line. A discharge current as shown in FIG. 10D flows through the discharging cells. In the figure, Tvsync is one frame period (one vertical synchronization period), for example, 1
It is set to 6.7 ms (1/60 seconds).

When the AC type plasma display is driven by the memory as described above, data is written in all lines except the line (refresh line) which is sequentially rewritten along the scan line and in which display rewriting is performed. The discharge cells are discharged and lit, and this discharge is repeated at intervals of 5 to 10 μs, for example. Similar driving is also performed in a DC type memory type plasma display and an active matrix type LCD to improve brightness and contrast.

[0018]

As described above, since the panel display for displaying the memory effectively uses the time in the frame, the display is performed until the display of the corresponding line is rewritten in the next frame. Is continuing. Therefore, when a moving image (moving characters, graphics, etc.) is displayed, the line may appear double.

FIG. 11 explains the above-mentioned phenomenon. In FIG. 11, the vertical line is moved from right to left, and the moment the n-th line is rewritten (in the figure, the circled circles with diagonal lines are lit). The white dots indicate the dots that were lit in the previous frame). Here, in the data rewriting drive cycle, the n-th line erases the data of the previous frame (that is, erases the dot with a hatched circle on the right side of the n-th line), and at the next moment, removes one dot left dot. Since the light is turned on, it appears that two dots are turned on at that moment, and by repeating this, the vertical line is doubled. Actually, when a cursor is moved or a display is moved such as a smooth scroll display like when the mouse is moved, such an illusion phenomenon that a line is duplicated appears. Further, even when video display is performed using gradation display, it is conceivable that a double image of a contour may occur in a moving image.

The present invention has been made to solve the above problems, and even when the above-mentioned smooth scroll display or the like is moved, a double image (for example, a line) of a moving image or a double image of an outline is displayed. It is intended to prevent the occurrence of such.

[0021]

According to an aspect of the present invention to solve the above-mentioned problems, there is provided a method of driving a display device for performing a memory display, in which each line is sequentially processed within each frame period. Provided is a method for driving a display device, which comprises setting a display period for rewriting display data for a display element of a line and a non-display period for sequentially performing an erasing operation for all display elements of the line for each line. To be done. According to another aspect of the present invention, there is provided a method of driving a display device, wherein the display period and the non-display period are alternately set for each frame.

[0022]

According to the above construction, by limiting the display period within a frame and forcibly providing the non-display period, the period immediately before starting a new display in the next frame is set as the display interruption period, and It is possible to prevent the phenomenon of double reflection. Alternatively, by alternately providing the display period and the non-display period for each frame, the non-display period becomes a display interruption period, and the double-shot phenomenon can be prevented.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a panel drive timing chart as an embodiment of the present invention, which is characterized in that a forced erase scan is performed in the middle of each frame. That is, the first scan (indicated by scan line 1) in each frame is performed to sequentially write the display data in each line, and the scan line 1 corresponds to the scan line in FIG. To do. And the scan
In the first drive cycle (drive cycle in which rewriting is performed) of each line sequentially along the line 1, the drive wave as described in FIG. 7 is applied to each discharge cell of the line to write the display data. During the display period shown in FIG. 1, the discharge cells in which the display data has been written in this manner are maintained in the above-described sustain discharge in the subsequent drive cycles and are lit by discharge.

A second scan (indicated by scan line 2) in each frame is then performed to sequentially force each line for a forced erase operation. That is, in the first driving cycle of each line sequentially along the scan line 2, a horizontal electrode waveform (that is, an erase pulse EP exists but a write pulse WP exists as shown in FIG. 2B) for the line. A drive wave having (not existing) is applied, and all the discharge cells in the line are extinguished by the erase pulse EP, thus setting the display interruption period.

The write cancel pulse WC existing in the vertical electrode waveform (shown in FIG. 2A) in this drive cycle functions as display data for other lines in the display period at that time. , Whether or not to write data to each discharge cell in another line which is in the display period and is in the driving cycle in which data is rewritten at that time, depending on whether or not the pulse WC is output. It is determined. Note that FIG.
In the drive timing chart shown in FIG. 10, when gradation display is performed, the display period in FIG. 1 may be divided into several subfields as in the case shown in FIG.
The above 1 frame (1 vertical synchronization period) is usually 20 ms
It is set from (1/50 second) to 16.7 ms (1/60 second).

FIG. 3 shows the relationship between input data and internal data according to another embodiment of the present invention. The display period (lighting period) and the display interruption period (extinguishing period) for each frame. They are set alternately (for example, odd number frames and even number frames). Therefore, as shown in FIG. 3A, the frame frequency is almost doubled from the conventional one (that is, one frame period is, for example, 10 ms (1/100 second)).
Then, for example, one screen is displayed in odd frames (that is, input data for each line as described in FIG. 10B is directly taken as internal data (that is, transferred to the vertical electrode driver from the outside), As described with reference to FIGS. 10B and 10C, it is determined whether or not the corresponding discharge cell is turned on according to the presence or absence of the erase cancel data EC). The erase pulse E described with reference to FIG. 10C is set by setting the internal data transferred from the vertical electrode driver to “0” (that is, the erase cancel data EC is set to “0” for all discharge cells of each line).
P is valid), and all the discharge cells of each line are turned off (see FIGS. 3B and 3C). In other words, in the even-numbered frame, the erase-cancellation data EC as display data are all set to the ground level (as blank data), and display is suspended for all discharge cells in each line.

FIG. 4 is a timing chart of the input data and the n-line drive waveform in the odd frame of the embodiment described with reference to FIG. 3, and the relationship between the input data and the n-line drive waveform in the odd frame. Is shown in FIG.
This is equivalent to the case described in (B) and (C) (only one frame period is set to about 10 ms as described above, so that one driving cycle period (one horizontal scanning period) is about 2).
4 μs). That is, in the odd-numbered frame, each discharge cell in each line has the erase pulse EP (FIG. 4C) in the data rewriting drive cycle.
Is applied, the erase cancel data (erase cancel pulse) EC from the opposite line side (for example, from the vertical line side) EC (shown in FIG. 4B as the nth line data is generally shown. Whether or not writing is performed in the discharge cell (that is, whether to turn on or turn off) is determined depending on whether or not the discharge cell is applied.

On the other hand, FIG. 5 shows a timing chart of the input data and the n-line drive waveform in the even frame of the above-mentioned embodiment, and in this even frame, as described above,
The data transferred internally are all "0" as shown in FIG. 5 (B). (In this way, the erase cancel data (erase cancel pulse) EC is written to all discharge cells of each line. As shown in FIG.
As shown in FIG. 5D, the erase pulse EP for all discharge cells is made effective as shown in FIG. 5C, and the data EC is not output in this way (that is, blank data). In addition, all the discharge cells in each line are extinguished without generating the sustain discharge. As described above, in this embodiment, the frame frequency is approximately doubled from the conventional one (for example, changed from 60 Hz to 100 Hz), one frame of display is displayed for each frame, for example, in odd frames, and the display data of even frames is This is to alleviate the above-described phenomenon of double image by not displaying the blank data as described above.

[0029]

According to the present invention, when the display device is driven, the display period and the non-display period are alternately set at a predetermined ratio, so that a double image of a moving image, a double image of a contour, and the like are displayed. It is possible to improve the display quality of the display device.

[Brief description of drawings]

FIG. 1 is a panel drive timing chart as one embodiment of the present invention.

FIG. 2 is a timing chart of drive waveforms during an erase operation for each line in the display interruption period of FIG.

FIG. 3 is a timing diagram of input data and internal data according to another embodiment of the present invention.

FIG. 4 is a timing diagram in an odd frame of input data and an n-line drive waveform according to another embodiment of the present invention.

FIG. 5 is a timing chart in an even frame of input data and an n-line drive waveform according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating a plasma display device to which the present invention is applied.

7 is a timing chart of drive waveforms when writing data to each line in the device of FIG.

8 is a panel drive timing chart as a conventional example for the apparatus of FIG.

9 is a panel driving timing chart when gradation display is performed on the device of FIG.

FIG. 10 is a timing chart of input data and an n-line drive waveform as another conventional example.

FIG. 11 is a case 2 in which a panel is driven by a conventional technique.
It is a figure explaining the phenomenon of multiple images.

[Explanation of symbols]

 1 ... Power supply circuit 2 ... Control circuit 3 ... Vertical electrode driver 4 ... Horizontal electrode driver 5 ... Panel EP ... Narrow erase pulse WP ... Write pulse WC ... Write cancel pulse MP ... Sustain pulse

Claims (4)

[Claims] 1. A method of driving a display device for performing a memory display, comprising: a display period in which display data for display elements of the line is sequentially rewritten in each frame period, and a display period in each line is sequentially rewritten. A method of driving a display device, comprising setting a non-display period in which an erasing operation is performed on all display elements of the line. 2. A method of driving a display device for performing memory display, comprising: a first frame period in which display data for display elements of the line are sequentially rewritten for each line; A method for driving a display device, comprising alternately setting a second frame period in which an erasing operation is performed on all display elements. 3. The method according to claim 1, wherein the erase operation for all display elements of the line is performed by applying an erase pulse to the line and then prohibiting application of a write pulse to the line. 4. When the erase operation is performed on all the display elements of the line, when the write pulse is first applied to the line and then the erase pulse is applied, the output of the cancel pulse to all the display elements is prohibited. The method according to claim 1 or 2, which is performed by.