JP2908410B2 - Display device, drive circuit and gradation display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a gas discharge panel,
The present invention relates to a display technique for an EL display device, a fluorescent display tube, a liquid crystal display device, and the like.

[0002]

2. Description of the Related Art Conventionally, as a technique for displaying a gradation of an image on a matrix panel, for example, Kaji et al .: IEICE Technical Report on Image Engineering, Document No. IT72-45 (197)
3-03) (1973.3.12) There is a memory type gas discharge panel described in "Display of halftone moving image by AC type plasma display". In the prior art, for example, in an 8-bit gray scale, each subfield is divided into b0, b1, b2,
.., B7 (b0: subfield with the shortest display period (lowest subfield), b7: subfield with the longest display period (highest subfield)), arrangement order of subfields for representing gradation Is the order of b0, b1, b2,... B7, in which the display period gradually increases within one field time (for example, 1/60 second (s) (about 16.7 ms for NTSC television signals)). ing.

[0003]

In the above-described subfield arrangement in the prior art, the image quality of a moving image deteriorates, and the moving image appears to be grayed-out or the pixels appear to be coarse.

The problems to be solved by the present invention will be described below with reference to FIGS. 2 to 5 by taking a gray scale display technique in the case of a gas discharge television as an example.

FIG. 2 is a diagram showing an example of a sectional structure of a cell of a three-electrode gas discharge panel. On the substrate 200, the first electrode (cathode) 220, Ba or Ni, are formed of a material such as LaB _6. On the other hand, a third electrode (display anode) 240 is formed on the face plate 210 by a printing technique or the like. The discharge space (display discharge space 250 and auxiliary discharge space 27)
0) is formed by a laminated structure of spacers and the like, and the second electrode (auxiliary anode) 230 is also provided at a predetermined position.

When a discharge (display discharge) occurs between the first electrode (cathode) 220 and the third electrode (display anode) 240, the gas (Xe or Ne-Xe, H) in the display discharge space 250 is generated.
e-Xe or other mixed gas) to generate ultraviolet rays,
0 is emitted and display is performed. An auxiliary discharge, which is a so-called pilot discharge, is generated between the first electrode 220 and the second electrode (auxiliary anode) 230. Whether or not this auxiliary discharge shifts to a display discharge between the first electrode 220 and the third electrode 240 depends on whether or not a pulse voltage is applied to the second electrode 230.

FIG. 3 shows a matrix type gas discharge panel 30.
It is a figure which shows the example of a connection structure of 0 electrode and an electrode lead wire.
The first and third electrodes of the cell 350 of the gas discharge panel are:
(In this example, and the number of electrode leads 480, K ₁ number from the top in the order of each lead, K _2, ... are the K ₄₈₀₎ the first electrode lead 310 laterally and the third electrode lead wire 3
40 (in this example, the number of electrode leads at 480, A _1, A ₂ from the top the number of each lead wire, ... is set to A ₄₈₀₎ is connected to, the second electrode second electrode in the longitudinal direction Lead wires (auxiliary anode lead wires) 320 and 330 are connected.

FIG. 4 shows a waveform of a voltage applied to the electrodes.

In FIG. 4, V _K denotes a first electrode lead wire 3.
A waveform 400 of a voltage applied to the first electrode via 10 and a pulse 400 for addressing one line in the matrix panel (hereinafter, referred to as a first electrode address pulse).
In FIG. 4, the pulse width of the first electrode address pulse is equal to the time width Δ (= 1H / number of gray scale bits, H: horizontal scanning period) assigned to address one line. . For example, when a television signal is displayed in 8-bit gradation (256 gradations), the time width Δ is Δ
≒ 7.9 μs.

In FIG. 4, Vs is a pulse (second electrode pulse) 41 applied to the second electrode via the second electrode lead wire.
0 is a voltage waveform. The second electrode pulse 410 has a smaller pulse width than the first electrode address pulse 400,
It is located behind the time width Δ. The second electrode pulse may or may not be present depending on the content of the television signal.

Further, _VA is applied to the third electrode via the third electrode lead wire.
5 is a waveform of a voltage applied to an electrode. For the same line number of the first electrode lead and the third electrode lead,
The voltage of the pulse 420 is applied to the first electrode address pulse 400
Immediately after, the voltage is continuously applied to the third electrode a number of times corresponding to the display period of the subfield.

Next, the discharge between the electrodes will be described with reference to periods I, II, and III in FIG.

When the voltage of the address pulse 400 is applied to the first electrode, a discharge, that is, an auxiliary discharge occurs between the first electrode and the second electrode in a period I. This auxiliary discharge occurs in the auxiliary discharge space 270 (FIG. 2). Since there is no phosphor on the wall surface of the auxiliary discharge space 270 and the auxiliary discharge space 270 is located at a position hidden from the front side of the panel, the auxiliary discharge has little effect on display image quality.

Next, during the period II in which the voltage of the pulse 410 is applied to the second electrode, the potential difference between the first electrode and the second electrode is reduced, so that the discharge between the first electrode and the second electrode is reduced. Stops. However, as described above, since the pilot discharge (auxiliary discharge) has already been performed in the period I, the first discharge is performed in the period II.
Many space charges exist near the electrodes. Therefore, a new discharge, that is, a display discharge occurs between the first electrode and the third electrode. The transition of the discharge from the second electrode to the third electrode in this manner is referred to herein as switching. When this switching is performed, a large number of charged particles are generated in a discharge path (display discharge space 250) between the first electrode and the third electrode.

Next, in period III, first, the third electrode
The voltage of the pulse 420 having a small width is applied. Period II above
As a result, a large amount of charged particles are present in the display discharge space 250, and a discharge is generated between the first electrode and the third electrode by the voltage of the pulse 420. Due to this discharge, charged particles are further generated in the display discharge space 250, and the discharge is caused by the voltage of the next pulse 430. Thus, in the period III, this discharge continues during the period in which the pulse voltage is continuously applied. This is called a pulse memory. This discharge causes the phosphor 260 to emit light and display is performed. This discharge stops even when the pulse voltage is continuously applied, when a new voltage is applied to the first electrode.

In the case where the panel does not emit light for display, FIG.
Pulse 410 is not applied to the second electrode. In this case, the switching is not performed and the first
No discharge occurs between the electrode and the third electrode. Therefore, the number of charged particles in the display discharge space 250 is small. Therefore, the third
Even if the voltages of the pulses 420 and 430 are applied to the electrodes, no discharge occurs and the phosphor 260 does not emit light. As described above, the discharge between the first and third electrodes can be controlled by controlling the presence or absence of the pulse 410 of the second electrode, and the display light emission of the panel can be controlled.

Next, with reference to FIG. 5, an example of an 8-bit gray scale (256 gray scale) image display in the case of a gas discharge panel will be described.

FIG. 5 is a diagram showing an example of the waveform V _{K of} the voltage applied to the first electrode and the waveform _VA of the voltage applied to the third electrode during one field. A voltage of eight pulses 400 corresponding to the subfield is applied to the first electrode during one field. Each of the eight pulses 400 is referred to as an address pulse in each subfield b0, b1, b2,. As shown in FIGS. 4 and 5, the voltage of the pulse 420 applied to the third electrode is repeatedly applied immediately after the application of the address pulse 400, and ends before the next subfield address pulse 400 comes. Pulse 420 is
In each of the subfields b0, b1, b2,..., A display period corresponding to each subfield is formed.

Each of the subfields b0, b1, b2... B7
, The ratio of the number of pulses of the pulse 420 in each subfield to the subfields b0, b1, b2,.
If the ratio is 2: 4: 8:...: 128, this combination constitutes 256 gray levels of the binary code of the image. It is determined whether the panel is to be displayed by the voltage of the pulse 420 applied to the third electrode during the period corresponding to the address pulse 400 in each of the subfields b0, b1, b2,. 410).

In a conventional gradation display, as shown in FIG.
From the lowermost (shortest display period) subfield b0 to progressively higher (longer display period) subfields,
That is, they are arranged in the order of b0, b1, b2,.
In this case, as shown in Table 1, when the gradation level changes by one level between level 127 and level 128, when the level is 127, display is performed in seven subfields b0 to b6, When the level is 128, display is performed only in the subfield b7.

[0021]

[Table 1]

As is apparent from FIG. 5, in the case of the conventional technique, the level 127 is displayed in a certain field,
When displaying the level 128 in the next field, the time width of one field (about 16.7
ms), there is a period in which the display unit does not emit light at all. Especially in the case of moving images, the image quality is significantly degraded due to this.
The gradation appears to be dropped, or the pixels appear to be coarse.

Table 2 shows the case of another gradation level. As shown in Table 2, when the gray level changes between adjacent fields, when the gray level changes between level 63 and level 64, when the level changes between level 31 and level 32, or when level 15 and level When it changes between 16,
Further, like the change between the level 191 and the level 192, when the level changes between the level 63 and the level 64 with reference to the level 128 of the subfield b7, a long non-light emitting period is generated in the display unit. There is image quality degradation for moving images. This deterioration in image quality is remarkable in the case of a display with high luminance.
If the brightness is low, it is difficult to observe.

[0024]

[Table 2]

As described above, in the above prior art,
Since the order of the subfields is the order of b0, b1,... B7, the image quality of the moving image is degraded.

An object of the present invention is to provide a gradation display technique which does not cause such image quality deterioration.

[0027]

In order to achieve the above object, according to the present invention, there are provided: (1) a plurality of subfields within one field period;
And a portion forward to the three or more sub-fields number three or more sub-fields in the order is increased less a part to be arranged in the display pulses allocated to each subfield is arranged chromatic vital both said portions The display pal within the range
Are arranged so as to include the subfield having the largest number of pulses, and the image of the gradation level corresponding to the number of the display pulses assigned to the subfield which is activated for display among the arranged subfields is formed. Display it on the display.

[0028] (2) a plurality of subfields within one field period, less the portion of the number three or more sub-fields in order of increases is <br/> array of display pulses allocated to each subfield 3 or more sub fees in order
And a portion field are arranged within the perforated vital both said portions
The subfield with the largest number of display pulses is included.
It arranged so that, to vary the gray level different combinations of subfields to be actuated state for display of the sequence sub-field.

(3) In a display device for displaying an image having a gradation by using a subfield, within one field period
A plurality of sub-fields, the first array portion and least comprising three or more support in the order in which two or more sub-fields in order of the number is a number of allocated pulses is distribution <br/> columns for display
And a second sequence portion subfields are arranged, the
A sensor disposed between the first array portion and the second array portion.
Subfield is the subfield with the largest number of pulses
And located at approximately the center of the one-field period,
The first array portion and the first array portion are arranged so as to form a portion in the order of increasing number of pulses, and correspond to the number of the pulses assigned to the subfield which is activated for display among the array subfields. The image of the gradation level is displayed on the display unit.

(4) A plurality of sub-fields in one field period are divided into a first arrangement portion in which two or more sub-fields are arranged in the order of increasing the number of pulses allocated for display and three in the order of decreasing number. A second arrangement portion in which the above subfields are arranged, and wherein the number of pulses is the largest between the first arrangement portion and the second arrangement portion.
Subfields are arranged, and the subfield having the largest number of pulses
Of the pulse with at least the first array portion
Arrangement is made so as to form a portion in the order of increasing number , and a gradation level is changed by changing a combination of subfields which are activated for display among the arranged subfields. In addition, multiple subfields within one field period
In order of increasing number of pulses assigned for display.
First arrangement section in which three or more subfields are arranged
Two or more subfields are arranged in ascending order.
A second sequence portion, and the first sequence portion
Between the second array portion and the sub array having the largest number of pulses.
Field and the subfield with the largest number of pulses
A small number of pulses with at least the second array portion
Are arranged so as to form portions in the order of
Subfield that is activated for display in the field
In this case, the gradation level is changed by changing the combination of the colors.

[0031] (5) 3 a plurality of subfields within one field period, in the order in which three or more sub-fields number in the order becomes more pulses allocated for display is reduced a first sequence portion that is arranged have a second sequence portion or more sub-fields are <br/> sequence range of the both sequence portion
The subfield with the largest number of pulses is included in the box ,
Next to the subfield having the largest number of pulses, the number of pulses is 2
The display section arranges the image so as to be the next most subfield, and displays the image of the gradation level corresponding to the number of the pulses assigned to the subfield which is activated for display among the arranged subfields. To be displayed.

(6) In a display device for displaying an image having a gradation by using a subfield, within one field period
The subfields having the largest number of display pulses are arranged before and after the subfield having the largest number of display pulses.
Subsequent to the field, another subfield of the pulse number is
As the distance from the subfield having the largest number of display pulses is increased , two or more pulses are arranged in the order of decreasing the number of display pulses.
On the other side, three or more are arranged side by side, and the display pattern assigned to the sub-field which is activated for display.
An image having a gradation level corresponding to the number of pulses is displayed on the display unit.

In the above-described subfield arrangement, the positions of the operation subfields (subfields in which the display section is driven to display by driving the display section with the pulses for display) are dispersed at the halftone level, and adjacent subfields are dispersed. Between the fields, a subfield corresponding to the gradation level after the level change in the succeeding field from the end of the display period of the sub-field corresponding to the gradation level before the level change in the preceding field. , The time to the start of the display period of the first operation subfield is shortened.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS.

As is apparent from the above, in order to improve the image quality deterioration, basically, a plurality of sub-fields are divided into a display period in which a predetermined number of display pulses are allocated in one field period. What is necessary is just to arrange in the order which disperse | distributes. In such an arrangement, a light emission period always exists within one field period even if the level 127 and the level 128 in Table 1 change for each field. Hereinafter, the plurality of sub-fields b
0, b1, b2,..., B7, and the subfield is placed adjacent to the uppermost subfield (the subfield of the longest display period (b7 in the above example)) and the subfield b5 of the shorter display period. And b6 are arranged, and the uppermost subfield b7 is arranged substantially in the center of the field (FIGS. 1 and 6). A configuration example (FIG. 7) will be described.

FIG. 1 shows an example of a configuration of a subfield arrangement according to the present invention. Subfields in one field are represented by b1, b3, b5, b7, b6, b4, b2, b0.
And an example of a voltage waveform V _K applied to the first electrode and a voltage waveform _VA applied to the third electrode. The display period of each subfield is the same as that of the prior art shown in FIG. The number of pulses 420 (pulses for display) applied to the third electrode and assigned to each subfield also corresponds to the display period of each subfield. Is the same as In the subfield arrangement of FIG. 1 as well, a change between subfields having low gradation levels, such as a change between b0 and b1 at the time of field switching, is due to a change in a dark display level area. ,
Even if the non-light emitting time is long, the deterioration of the image quality is not noticeable.

FIG. 6 shows another example of a subfield arrangement according to the present invention. That is, subfields within one field are represented by b0, b2, b4, b6, b7, b
5, in a case arranged in the order of b3, b1, showing an example of a voltage waveform V _A applied to the voltage waveform V _K and the third electrode to be applied to the first electrode. In this case, as in the case of the embodiment of FIG. 1, the display period of each subfield is the same as that of each subfield in the prior art of FIG.

FIG. 7 shows an embodiment of the apparatus of the present invention, and shows a specific example of the structure of a gas discharge television. Video signals 810, 820, 830 separated into R, G, B color signals
Are converted from analog signals to digital signals by A / D converters 840, 850, and 860, respectively, and stored in the frame memory 870. The frame memory 8
The readout of the signal from 70 is performed by a dedicated readout ROM 9.
00, it is performed at a timing that matches the time of the subfield array of the present invention. The ROM 900 is operated by a counter 890 that counts a clock signal 880. The counter 890 outputs a V signal (vertical synchronization signal) of a television signal or an H signal (horizontal synchronization signal) as necessary.
Reset using. The signals read from the frame memory 870 are input to the shift registers 1010 and 1030, where the signals are subjected to serial-parallel conversion, and then converted into high-voltage signals necessary for driving the panel 800 by the second electrode drivers 1020 and 1040. Then, it is input to the second electrode of the panel. In the embodiment shown in FIG. 7, the device configuration is a two-row simultaneous driving system in which the second electrode is driven separately in the upper half and the lower half of the panel. It is provided in.

On the other hand, the signal input to the first electrode (FIG. 1,
The logic signal V _K in FIG. 6) is generated by the ROM 920 and is shifted by 1H in the shift register 98.
0, 970, and after serial-parallel conversion, the signals are converted into high-voltage signals by the drivers 1000, 990 and input to the first electrode of the panel.

The signal input to the third electrode (FIG. 1,
The logic signal V _A in FIG. 6) is generated by the ROM 910 and is shifted by 1H in a shift register 93.
0, 940, and after serial-parallel conversion, converted into a high voltage signal by drivers 950, 960 and input to the third electrode of the panel.

Although the embodiments of the present invention have been described with reference to a gas discharge television, the scope of the present invention is not limited to this.
In addition, for example, an EL display device, a liquid crystal display device, a fluorescent display tube, and the like, such as a matrix panel that digitally performs luminance modulation by a pulse width or the number of pulses are also included.

[0042]

According to the present invention, it is possible to improve the image quality of moving images under a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a subfield arrangement according to the present invention.

FIG. 2 is a sectional view of a cell of the gas discharge panel.

FIG. 3 is a diagram showing wiring of a gas discharge panel.

FIG. 4 is a diagram illustrating driving of a gas discharge panel.

FIG. 5 is an explanatory diagram of a conventional gradation display technique.

FIG. 6 is a diagram showing another embodiment of a subfield arrangement according to the present invention.

FIG. 7 is a diagram showing one embodiment of the apparatus of the present invention.

[Explanation of symbols]

220: first electrode, 230: second electrode, 240: third electrode, 250: display discharge space, 270: auxiliary discharge space, 400: first electrode address pulse.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Shinichi Shinada, Inventor 1-280 Koikurakubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory Co., Ltd. (72) Inventor F.S. C. Curzon 1-280 Koikurakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Kuni Kitagawa 3681 Hayano, Mobara-shi, Chiba Pref. Hitachi Device Engineering Co., Ltd. (56) References (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G09G 3/00-3/38

Claims (11)

(57) [Claims] 1. A 1 a plurality of sub-fields in a field period, parts and less becomes order three or more three or more sub-fields in order of the number is a number of display pulses allocated to each subfield is arranged the display and a portion subfield is <br/> arranged within the perforated vital both said portions
Are arranged so as to include the subfield having the largest number of display pulses, and correspond to the number of display pulses assigned to the subfields that are activated for display among the arranged subfields . A display device, characterized in that an image of a gradation level is displayed on a display unit. 2. A 1 a plurality of sub-fields in a field period, parts and less becomes order three or more three or more sub-fields in order of the number is a number of display pulses allocated to each subfield is arranged the display and a portion subfield is <br/> arranged within the perforated vital both said portions
Arranged such that the number of use pulses include largest subfield, characterized in that so as to vary the gray level different combinations of subfields to be actuated state for display of the sequence subfields Display device. In the display device according to claim 3 Using the subfield to display an image having a gradation, a plurality of subfields within one field period, pulses allocated for display numerous and becomes sequentially to two or more
A first arrangement part in which the subfields are arranged and a second arrangement part in which three or more subfields are arranged in decreasing order, wherein the first arrangement part and the second arrangement part
And the subfield located between
Of a subfield arranged to form a forward portion number of pulses with the position at least sequence portion of the first substantially at the center increases in the one field period, for display of the sequence subfields A display device characterized in that an image having a gradation level corresponding to the number of pulses assigned to a subfield to be activated is displayed on a display unit. 4. A method according to claim 1, wherein a plurality of sub-fields within one field period are divided into a first arrangement portion in which two or more sub-fields are arranged in an order of increasing the number of pulses allocated for display and a number of three or more in a decreasing order. subfield and a second sequence portion that is arranged, and the number of the pulses is arranged, most of the sub-field pulses during the sequence portion and the second sequence portion of the first The most subfields
At least the first array portion has a large number of the pulses.
A display device which is arranged so as to form a portion in the order of appearance , and changes a gradation level by changing a combination of subfields which are activated for display among the arranged subfields. A plurality of sub-fields wherein one field period, a first sequence portion and less becomes the order three or more three or more sub-fields in order of the number is a number of pulses allocated to the display are arranged subfield have a second sequence portion that is arranged, in the range of the both sequence portion
The number of the pulses contain most of subfields, operation next to the pulse largest number of sub-fields are arranged so that many subfields in the second number of the pulse, for display of the sequence subfields A display device characterized in that an image of a gradation level corresponding to the number of pulses assigned to a subfield to be in a state is displayed on a display unit. 6. A display device using a subfield for displaying an image having a gradation, a plurality of subfields within one field period, the display path before and after the sub-field number most of display pulses
Following the sub-field having the largest number of pulses, the sub-field having the other number of pulses is two or more on one side and 3 on the other side in the order in which the number of display pulses decreases as the distance from the sub-field having the largest number of display pulses increases. Or more pixels are arranged side by side, and an image of a gradation level corresponding to the number of display pulses assigned to the subfield that is activated for display is displayed on the display unit. Display device. 7. A display device for displaying an image having a gradation by causing a matrix panel to emit light by using a display pulse of a subfield, a memory means for holding an image input signal, and a first signal read from the memory means. First drive signal output means for forming and outputting a first drive signal for driving a first electrode of the matrix panel based on a signal; and a drive signal for driving a second electrode of the matrix panel. In a plurality of subfields within one field period, three or more subfields are arranged in order of increasing number of display pulses.
Order three or more sub which Rudo decreases a part to be arranged
Possess a portion subfields are arranged, range of the both portions
The sub-field with the largest number of display pulses is included in the box.
A second drive signal output means for forming and outputting a second drive signal arranged so as to be rare ;
Based on the driving of the second electrode corresponding to the number of display pulses,
A matrix panel that controls the light emission of the panel unit and displays an image with gradation on the panel unit. 8. A driving circuit for driving a display section by subfields, wherein a plurality of subfields in one field period are divided into three or more subfields in an order of increasing the number of display pulses assigned to each subfield. three or more sub-fields in order of less the portion to be arranged is closed and a portion to be arranged, the number of the display pulses in the range of the both portions
A drive circuit wherein drive signals arranged so as to include the most subfields are output. 9. Within a one-field period, a plurality of sub-fields are divided into three in a first arrangement portion in which three or more sub-fields are arranged in an increasing order of the number of pulses assigned for display and in a decreasing order of three. have a second sequence portion or more sub-fields are arranged, within the scope of the both sequence portion
Include the subfield with the largest number of pulses
Gradation display method characterized by forming the indicator drive signal sequence was to display an image a more gradation on the display section drive signal to the display unit. 10. A display device for displaying a gradation image by causing a matrix panel to emit light by using a display pulse in a subfield, a memory means for holding an image input signal, and a first signal read from the memory means. A first drive signal output means for forming and outputting a first drive signal for driving a first electrode of the matrix panel from the signal of (a), a drive signal for driving a second electrode of the matrix panel, A plurality of subfields within one field period are divided into three or more subfields in the order of increasing number of display pulses.
The first array part where the fields are arranged and in decreasing order
Three or more sub-fields have a second sequence portion that is arranged, the number of the display pulses in the range of the both sequence portion
There contains most of the sub-fields, to form a second driving signal next to the sub <br/> subfield of said number of pulses most are arranged such that the number the pulse is often subfields in the second A second drive signal output means for outputting, and an upper drive signal for each subfield depending on a drive state of the first electrode.
Based on the driving of the second electrode corresponding to the number of display pulses,
A matrix panel that controls the light emission of the panel unit and displays an image with gradation on the panel unit. 11. Multiple sub fees within one field period
More pulses are assigned for display
First array in which three or more subfields are sequentially arranged
Two or more subfields are arranged in order of decreasing part
And a second arrangement portion, and the first arrangement portion
Between the minute and the second array portion, the pulse having the largest number of pulses.
Subfield with the largest number of pulses
Has a small number of pulses with at least the second array portion.
Arranged so as to form a part in the order of disappearance,
Subfields that are activated for display in the field
Changed the combination of fields to change the gradation level
A display device characterized by the above-mentioned.