JPH11242462A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the disturbance of gradation without lowering the brightness of a screen by making matrix panels emit lights based on a subfield arrangement signal making the interval between the point of the display pulse impression starting time of the first subfield being in a preceding field and the point of the display pulse impression starting time of the last subfield being in a succeeding field to be equal to or shorter than a critical fusion cycle. SOLUTION: Subfields are arranged by being crammed to the direction of one side of one field without assigning the whole of the field to subfields in this device. By constituting the device in such a constitution, the interval Tm between the point of the light emission starting time of the first subfield bo being in a field and the point of the light emission starting time of the last subfield b7 being in a next filed is made to be shorter than the critical fusion cycle (about 20 msec) of a visual characteristic. More-over, when the order of the subfields is reversed to be the order of b7 to b0 in the field, the time interval between the point of the light emission starting time of the b7 to the point of the light emission starting time of the b0 of the next field is made to be shorter than the critical fusion cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gradation display of an image, and relates to a technique for controlling the gradation by the display time of a display element.

[0002]

2. Description of the Related Art Conventionally, techniques for controlling a display time of a display element to display an image with a gradation include, for example, (1) Kaji et al.
72-45 (1973-03) (1973.3.12)
"Display of halftone moving images with AC plasma display"
There is a technology about a memory type plasma display described in the above. This means that a certain light emission time (for example, one field of a television signal) is time-distributed in correspondence with the display period of each subfield of a binary code, and the light emission is controlled by controlling the operation of each subfield. Control and
It controls the gradation of the image. In addition, as a television-related technology for displaying gradation by time division,
(2) Murakami et al .: Journal of the Institute of Television Engineers of Japan, vol. 38, N
o. 9 (1984) "Color TV display using an 8-type pulse memory type discharge panel" and (3) Kogami et al .: Television Society Technical Report vol. 13, No. 58 (198
9) Reactive power recovery of a Townsend light emitting gas discharge television is described.

In the former case ((1)), as shown in FIG. 11, one field is divided into eight subfields, and scanning and display of each of the subfields b7 to b0 are performed in this subfield. .

In the latter case ((2) and (3)), as shown in FIG. 12, one field is divided into eight time regions (b0 to b7) each having a length corresponding to each subfield of a binary code.
The scanning is shifted by 1H (horizontal scanning period) for each line, and the scanning pulse for the line address is slightly shifted in each subfield so that the selection of the line in each subfield does not become two lines at the same time.

[0005]

In the above prior art, the deterioration of the gradation display such as flicker may not be visually recognized depending on the device specifications. However, when the display screen becomes large or the luminance becomes high. When this happens, or when there is motion in the image, gradation disturbance such as flicker occurs. In the display technique of FIG. 11, since the light emission time between one field is short, the display screen is dark, and deterioration of the gradation display is not recognized. Further, in the display technique of FIG. 12, since the number of scanning lines is small, details of an image cannot be visually recognized. Therefore, in this case as well, no deterioration in gradation display is observed. However, for example, in a 40-inch class large gas discharge television whose brightness and screen size are higher than these, the maximum brightness of the image is set to 50 fL (Ｌ171 cd / m ² ) or more, and image display is performed in the same manner as in the above-described conventional technology. Is performed, remarkable gradation disturbance occurs in the moving image. That is, for example, when a face moves in displaying a person's face,
A phenomenon in which white streaks run on the cheeks occurs. In other words, in a smooth gradation display, when a display image moves (a so-called moving image), a streak is generated in the screen, and it is as if a certain gradation subfield is missing. This is a phenomenon that cannot be seen in a conventional cathode ray tube or the like.

The disturbance of the gradation in the moving image is caused by the instantaneous flicker of a specific pattern in the time division gradation display. This will be described using the conventional gradation display method of FIG.

FIG. 12 shows an example of a gray scale display of 256 gray scales (8-bit gray scale). For example, at the 127 gradation level, subfields b0 to b6 are activated, that is, the first half of one field emits light, and at the 128 gradation level at which the gradation of the next field is increased by one level, b7 is activated, ie, the second half of the field is activated. Moreover, part of the light is emitted.
That is, the operating position of the operating subfield changes greatly from the first half to a part of the second half in the field just by increasing the gradation by one level. The instantaneous light emission cycle at this time is from the light emission start time of the field b0 to the light emission start point of the next field b7, and the time interval is 25 msec. This cycle of 25 msec causes flicker and causes the gradation to be disturbed. When the image is a moving image, the gradation is disturbed one after another in a cell of the screen, and appears as a streak that can be visually recognized clearly.

Next, the principle of the time-division gradation technology including the flicker will be described. As a human visual characteristic, luminance L
It is known that the brightness sensation L when an image is displayed by alternately repeating 1 for t1 seconds and luminance L2 for t2 seconds is represented by L = (t1L1 + t2L2) / (t1 + t2) (Talbot- Plateau's Law (Television Handbook, Volume 1, Section 3.4, 55
page)). However, this rule is satisfied when flicker is not felt (called fusion time).

FIG. 13 shows a critical fusion cycle of visual characteristics when a luminance is changed by changing a white display light emission time width using a memory type gas discharge television, that is, turning on and off a light emitting element at a constant luminance. The measurement result of a cycle in which flicker cannot be identified when lighting is repeated at a constant cycle is shown. In the figure, the upper broken line indicates the last subfield (b) of the next field from the start of the display period of the first subfield (b7) in the field by the gradation display technique of FIG.
0) shows a time interval until the start of the display period (FIG. 11).
In this example, one field is equally divided into eight subfields). The broken line in the lower part of FIG. 13 indicates the display period of the last subfield (b7) in the next field from the start of the display period of the first subfield (b0) in the field by the gray scale display technique shown in FIG. 12 shows a time interval up to the start point (in the example of FIG. 12, the display period of each 8-bit subfield in one field is 1: 2: 4
..: Weighted to a ratio of 128). As can be seen from FIG. 13, in the conventional gray scale display techniques of FIGS. 11 and 12, the luminance is several fL or more, and the last subfield of the next field is started from the start of the display period of the first subfield in a certain field. The interval until the start of the display period exceeds the critical fusion cycle. Therefore, when the light emission of each subfield changes as in the case of a moving image, instantaneous flicker is felt particularly on a bright screen, and gradation is disturbed. Usually, the average luminance required for the display device is 50 f
Therefore, the critical fusion period of the visual characteristics is 20 or more.
msec or less is desirable, but if the value is in the vicinity of this value, even if this value is exceeded, the disturbance of the gradation is improved.

Further, in the above-mentioned prior art, the utilization rate of the time within one field as the light emission time is poor, that is, since the light emission time is short, the brightness of the screen is reduced.

An object of the present invention is to improve the disadvantages of the prior art, and to provide a technique capable of suppressing the disturbance of gradation even for a moving image or a high-luminance image.

[0012]

In order to achieve the above object, the present invention provides: (1) a display device which emits light from a matrix panel by means of a subfield and displays an image having a gradation; A memory means, and a first panel of the matrix panel based on 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 panel section of the first panel section; and a second drive section of the matrix panel based on a second signal read from the memory section. Second drive signal output means for forming and outputting a second drive signal for driving the first electrode of the first panel unit, and driving the second electrode of each of the first and second panel units All sub-fields which are weighted by the number of display pulses and are used for forming a gradation level of an image are arranged within a partial period in the field, and adjacent sub-fields are arranged in the first sub-field in the preceding field. Based on the subfield arrangement signal, the interval between the start of the application of the display pulse for the field and the start of the application of the display pulse for the last subfield in the succeeding field is shorter than the critical fusion period. A third drive signal output unit for forming and outputting a third drive signal for causing the panel to emit light, and a driving state of the first electrode for each subfield in each of the first and second panel units. The light emission corresponding to the number of the display pulses based on the driving of the second electrode is controlled, and an image having a gradation corresponding to the controlled light emission is displayed on the first and second panel sections, and And a matrix panel for forming an image.

(2) In a display device for displaying an image having a gradation by causing a matrix panel to emit light by a subfield, a memory means for holding an image input signal and the matrix based on 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 a first panel portion of the panel; and the matrix based on a second signal read from the memory means A second driving signal for forming and outputting a second driving signal for driving a first electrode of a second panel portion of the panel;
Drive signal output means, and a drive signal for driving the second electrode of each of the first and second panel portions,
Six or more subfields, which are weighted by the number of display pulses and are used as all the subfields used for forming a gradation level of an image, are arranged within a partial period in the field, and the adjacent subfields are the first subfield in the preceding field. A third drive for causing the matrix panel to emit light based on a subfield array signal in which the interval between the start of the application of the display pulse for the field and the start of the application of the display pulse for the last subfield in the succeeding field is shorter than the critical fusion period. A third drive signal output means for forming and outputting a signal;
In each of the second panel units, the light emission corresponding to the number of the display pulses based on the driving of the second electrode is controlled by the driving state of the first electrode for each subfield, and the control is performed. A matrix panel for displaying an image of a gradation corresponding to light emission on the first and second panel sections to form an entire image.

(3) In a display device for displaying a gradation image by causing a matrix panel to emit light by subfields, a memory means for holding an image input signal, and the matrix based on 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 a first panel portion of the panel; and the matrix based on a second signal read from the memory means A second driving signal for forming and outputting a second driving signal for driving a first electrode of a second panel portion of the panel;
Drive signal output means, and a drive signal for driving the second electrode of each of the first and second panel portions,
All sub-fields used for forming a gradation level of an image, weighted by the number of display pulses, are arranged within a partial period of the field, and the start of application of the display pulse of the first sub-field of the preceding field in the adjacent field A third driving signal for causing the matrix panel to emit light based on a subfield arrangement signal in which the interval between the start of application of the display pulse of the last subfield in the succeeding field is approximately 20 ms or less; In each of the first and second panel sections, the driving signal output means and the driving state of the first electrode for each subfield,
The light emission corresponding to the number of the display pulses based on the driving of the second electrode is controlled, and an image having a gradation corresponding to the controlled light emission is displayed on the first and second panel sections, and And a matrix panel for forming an image.

[0015]

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

FIG. 1 is an explanatory diagram of an embodiment of the present invention.
In this case, the number of scanning electrodes is 240, and the signal to be displayed is 8 bits (8 subfields b0, b1, b2, b3, b4, b
5, b6, b7), each bit is encoded by a binary code,
The configuration is such that 56 gradations can be displayed.

In FIG. 1, the vertical axis indicates the horizontal scanning electrode 2.
Forty rows (the upper half of the display panel), the horizontal axis shows the time for two fields (1/30 second). In this explanatory diagram, the subfields are arranged in one direction without allocating the entire time range of one field as a subfield. With such a configuration, the light emission start time (display period start time) of the first subfield b0 in the field and the last subfield b7 in the next field
(Tm) between the start of light emission (start of display period)
Is shorter than the critical fusion period of the visual characteristics (about 20 msec). The order of each subfield need not be limited to the order shown. Also, the light emission time may be packed in the field on the right side or on the left side. In FIG. 1, when the order of the subfields is reversed and the order of b7 to b0 is set in the field, the emission of b6 in the next field from the start of emission of b7 (start of the display period). The time interval until the start point (the start point of the display period) is shorter than the critical fusion cycle (about 20 msec).

FIG. 2 is a diagram showing an example of a circuit configuration in a gas discharge television device as a display device according to the present invention.
The video signals G, B, and R separated into green (G), blue (B), and red (R) color signals of the television signal are A / D converters 1-1, 1-2, and 1-3, respectively. From the analog signal
Bit (8 subfields b0, b1, b2, b3, b
4, b5, b6, b7) digital signal (binary code)
And stored in the frame memory (or field memory) 2. On the other hand, reading out of the frame memory 2 is performed by using a dedicated read-out ROM 5 so as to make a timing suitable for the gradation sub-field. The read ROM 5 is operated by the counter 4 that counts the clock signal CLK. The reset of the counter 4 is performed using a V (vertical synchronization) signal of the television signal or an H (horizontal synchronization) signal as necessary. Frame memory 2
Are read from each subfield (b0, b2,...) Of FIG.
This is performed by accessing the address where the bit signal of each scanning electrode is stored at the timing of b7). Each subfield signal read from the frame memory 2 is applied to shift registers 8 and 11 of a driver circuit for an auxiliary anode of the light emitting element, and further passes through drivers 9 and 10 to output signals of the light emitting element constituting the gas discharge panel 3. Are applied to the auxiliary anodes S1, S2, S3,..., S1 ', S2', S3 ',.

On the other hand, the ROM 6 for the cathode and the ROM 7 for the anode
Respectively use the output of the counter 4 to convert the arrangement signals of the subfields into the shift registers 13, 14 and 17, 18.
Add to Further, shift registers 13, 14, and 1
The signals from 7 and 18 are applied to drivers 15, 16 and 19 and 20, respectively, where the driving signals for the anode and cathode of the light emitting element of the gas discharge panel 3 are generated. The anode of the light emitting element has anode lead wires A1, A2, A3.
A480 are provided, and the cathode is provided with cathode leads K1, K2, K3... K240 and K241. These ROM, shift register and driver constitute a drive circuit for selecting a light emitting element to be displayed. Note that, in the case of this configuration example, the gas discharge panel 3 is vertically divided into two parts, so that two scanning electrodes can be driven simultaneously.

FIG. 3 is a partially enlarged view of the gas discharge panel 3 and shows the electrode wiring of the light emitting element. The gas discharge panel 3
A plurality of light emitting elements 30 are arranged in a matrix of rows and columns. The light emitting element 30 has three electrodes of a cathode, an anode, and an auxiliary anode, and has a memory function. Each light emitting element 3
A first electrode lead 32 (k1, k2,... Kl) and a third electrode lead 31 (A1, A2,... Al) are provided on the cathode and the anode, respectively, in the lateral direction. Are provided with auxiliary electrode lead wires 33 (S1, S2,...) In the vertical direction. As described above, when the gas discharge panel 3 is set to the number of horizontal scanning electrodes 1 = 480 and the panel is vertically divided into two and driven simultaneously by two rows, the auxiliary electrode lead wires 33 are separated at the center of the panel. The first electrode lead 32 (k
, K1), the third electrode lead wire 31 (A1, A2,
.. Al) and the auxiliary electrode lead wires 33 (S1, S2,...) Are respectively provided with the cathode driver 19 (or 20) of FIG.
Drive signals from the anode driver 15 (or 16) and the auxiliary anode driver 9 (or 10) are added.

FIG. 4 is a diagram showing a cross section of the light emitting element 30. A first electrode (cathode) 22 is made of Ba, Ni,
It is formed of a material such as LaBa. On the other hand, a third electrode (display anode) 24 is formed on the face plate 28 by a printing technique. Also, the discharge space (display discharge space 25 and auxiliary discharge space 27) shown in the figure is formed by stacking a number of perforated spacers, and the second electrode (auxiliary anode) shown in the figure is formed.
23 are arranged. When a discharge (display discharge) occurs between the first electrode 22 and the third electrode 24, ultraviolet rays are generated from a gas (Xe or a mixed gas of Ne-Xe, He-Xe, etc.) in the display discharge space 25, and fluorescence is generated. The light body 26 emits light to perform display. A so-called pilot discharge (auxiliary discharge) is generated between the first electrode 22 and the second electrode 23, and this auxiliary discharge is transferred to a display discharge between the first electrode 22 and the third electrode 24. This is controlled by the presence or absence of a pulse applied to the second electrode 24. Since this auxiliary discharge does not excite the phosphor 26, it does not affect display light emission.

Next, a discharge state between the electrodes will be described with reference to FIG. In FIG. 5, Vk indicates a voltage waveform applied to the first electrode lead line, and 40 indicates a pulse for addressing one line of the gas discharge panel 3, which is referred to as a first electrode scanning pulse. In the example of FIG. 5, the pulse width of the first electrode pulse is the same as the time width Δ assigned for addressing one line. For example, when the scanning time of each line is 1H, 240 lines are addressed in one field (the number of lines in the upper half of a panel driven simultaneously by two lines), and 8-bit gradation display is performed, Δ ≒ 8 μsec. Vs indicates a pulse voltage waveform applied to the second electrode lead, and pulse 41 is a second electrode pulse, which has a smaller pulse width than the first electrode scanning pulse 40 and is located behind the time width Δ. The presence or absence of the second electrode pulse 41 changes depending on the content of the television signal, that is, “1” or “0” of the subfield signal. VA indicates the waveform of the pulse voltage applied to the third electrode lead wire. For the same line number of the first electrode lead wire and the third electrode lead wire, the width of the voltage applied to the third electrode in FIG. Immediately after the first electrode scanning pulse 40, the narrow pulse 41 is continuously applied by the number of pulses corresponding to the number of gradation bits.

In a period III in the drawing, a pulse 42 having a narrow pulse width is first applied to the third electrode. Since a large number of charged particles are present in the display discharge space 25 due to the switching in the period II, the pulse 42 causes the first electrode and the third
A pulsating discharge occurs between the electrodes. This pulsed discharge further generates charged particles in the display discharge space 25,
The next pulse 43 also discharges. As described above, in the period III, the discharge continues while the pulse is continuously applied or until a new voltage that stops the discharge is applied to the first electrode. This function is called a pulse memory function. By this pulse discharge, the phosphor 26 of FIG. 4 is excited to perform display light emission.

When no display light emission is required, the pulse 41 of the second electrode shown in FIG. 5 is removed. In this case, switching is not performed, and no discharge occurs between the first electrode and the third electrode, so that the number of charged particles in the display discharge space 25 in FIG. 4 is small. Therefore, even if the pulses 42 and 43 are applied to the third electrode, no discharge occurs, and the phosphor 26 in FIG. 4 is not excited.

Therefore, the pulse 41 of the second electrode serves to control the discharge between the first electrode and the third electrode, and the display brightness is controlled by the presence or absence of this pulse.

FIG. 6 is an explanatory diagram for displaying an image on the gas discharge panel 3 in 256 gradations using an 8-bit binary code.
One field in FIG. 1 (about 1 in the case of an NTSC television signal)
/ 60 seconds = 16.7 msec). FIG. 3 shows the voltage waveform Vk applied to the first electrode and the third waveform.
5 shows a voltage waveform VA applied to an electrode. 1 for the first electrode
Eight scanning pulses 40 corresponding to each subfield are applied between fields. Pulse 42 applied to third electrode
Starts immediately after the application of the scanning pulse 40 and ends before the next scanning pulse 40 comes, as shown in FIG. The number of each of the pulses 42 is determined by the subfields b0, b1,.
It is proportional to the display period of b6 and b7, and its time interval ratio is 1:
2: 4: 8...: 128, 2
56 gradations are realized. The control as to whether or not to discharge the pulse train of each third electrode is performed in subfields b0 and b0.
1,..., B6 and b7, depending on whether or not there is a pulse (41 in FIG. 5) of the second electrode corresponding to the scanning pulse. In addition,
In FIG. 5, when the light emission in the period II cannot be neglected, the number of pulses of the third electrode is distributed in consideration of the luminance due to the light emission. Here, the period from the start of the display period of subfield b0 to the end of the display period of b6 in FIG. 6 is 3.3 m.
When the absolute value of the number of pulses of the third electrode is determined so as to be on the order of seconds, the above-described critical fusion period is 20 (= 3.3 + 1).
6.7) msec, and disturbance of gradation for a moving image can be suppressed.

In the configuration shown in FIGS. 1 and 6, the start of the display period of the first subfield of the subfield array in a certain field and the start of the display period of the last subfield of the subfield array in the next field In order to make the time interval (Tm) shorter than the critical fusion period of the visual characteristics, the entire display period is considerably shortened. However, in order to increase the emission time, at least one of the subfields of the binary code configuration is used. The same effect can be obtained by dividing one subfield and operating the divided subfield in a time zone different from the subfield operation time zone in the case of FIGS.

FIG. 7 and FIG. 8 are explanatory diagrams in the case of means different from the present invention.

In the embodiment shown in FIG. 7, the signal to be displayed is encoded by 8 bits (8 subfields b0, b1,..., B7), and the most significant subfield b7 is converted into the subfield b71.
And b72, and divide the emission time region of b71 and b72 by 1
It is assigned to the first and last positions of the field, and the emission order (operation order) of each subfield is b71, b0, b1,.
b2,... b5, b6, b72 (b71, b5,
... may be b1, b0, b72). In this case, b7
Subfields b0, b1, b2,... Excluding 1, b72
As seen from b5 and b6, the first subfield of the field is b0, and the last subfield of the next field is b0.
It becomes 6. The interval between the light emission start time (display time start time) of these two subfields is 20.8 msec, which is almost the same as the critical fusion cycle, and the image quality improvement effect of the moving image can be obtained. In the case of this embodiment, in the display device having the same configuration as that shown in FIG.
During about 1/60 second for a C television signal), the first electrode has nine sub-fields b71, b
Scan pulses corresponding to 0, b1,... B6, b72 are applied. The pulse 42 applied to the third electrode is a scan pulse 4
It starts immediately after the application of 0 and ends before the next scan pulse 40 comes. The number of each pulse is, for example, b7 to b71
And b72, the subfields b71, b71
0, b1,... B6, b72, the ratio of which is 64:
1: 2: 4: 8...: 64: 64. In this case, b
7 (pulse ratio 128, b7 = b71 + b72) ON
To operate (operate), two subfields b71 and b72 are turned on. The control as to whether or not to discharge the pulse train of each third electrode is performed in the subfield b7 shown earlier.
The determination is made based on the presence / absence of a pulse (40 in FIG. 5) of the second electrode corresponding to the scanning pulses of 1, b0, b1,... B6, b72.
Assuming that the scanning time of each line is 1H, 240
Lines (the number of lines in the upper half of a panel driven simultaneously by two lines) are addressed, and when b71, b0, b1,... B6, b72 are required to be controlled nine times, Δ = 1H / 9 = 7.05 μsec
Becomes When the vertical blanking period is used, Δ = 1 field / 240 × 9 = 7.72 μsec.

In the embodiment shown in FIG. 8, a signal to be displayed is coded by 8 bits (8 subfields b0, b1,... B7), and two subfields of subfields b6 and b7 are equally divided into b6 and b7. Is b61 and b62, b7 is b71 and b72, b61 and b71 are arranged at the beginning of the subfield arrangement in the field, b62 and b72 are arranged at the end, and the order in the field is b61, b71, and b61. b0, b
1, b2, b3, b4, b5, b62, b72. In this case, the first subfield in the field is b0, and the last subfield in the next field is b5. At this time, the interval between the light emission start points (display period start points) of the two subfields is 18.8 m.
sec, which is shorter than the critical fusion cycle (20 msec). In this example, the number of scanning pulses of the first electrode applied to one field is 10 per line, and the pulse width Δ is 1H / 10 ≒ 6.3 μs. ≒ 6.9 μsec.

FIG. 9 shows two of the field memories 91 and 92.
In order to further improve the image quality in the embodiment of FIG. 7, subfields b71, b72, b
6 is performed. Subfield b7
Is equally divided into two, b71 and b72, b6, b71,
All of b72 have the same display period (the number of pulses of the third electrode). At that time, b6 = 1, b7 = 0 (1; operation (O
N), 0; when not operating (OFF)), b71, b72,
One of the b6 may be set to the operating state (ON).
When 6 = 0 and b7 = 1, any two of b71, b72 and b6 may be set to the operating state (ON). At this time, which subfield is to be activated (ON) is determined in this example from the states of b6, b71, and b72 one field before. For example, in FIG. 9, when the second field is in a light emitting state, the previous field memory 91
According to the table of FIG. 10 through the arithmetic circuit 93 for comparing the signal of the field memory 92 with the subfield b
6, ON (1; operation) and OFF (0; non-operation) of b71 and b72 are determined.

FIG. 10A shows that the first field is b6 =
When 1, b7 = 0, the second field is b6 = 0, b
7 shows b6, b71, and b72 when 7 = 1.
Here, A indicates the subfields b0 to b5, and the cross indicates that the value does not depend on the value of A, that is, A may be any value. In addition, FIG.
This shows a case where b6 = 0 and b7 = 1 in the first field and b6 = 1 and b7 = 0 in the second field. As described above, for example, by controlling the subfields b6, b71, and b72 of the subsequent field between the adjacent fields according to the signal state of the previous field, the emission time can be dispersed, and the image quality of a moving image is improved. be able to. Note that b6, b71 when b6 = 1, b7 = 0, or b6 = 0, b7 = 1 from b6 = 0, b7 = 0,
The selection of the operation of b72 is determined from the state of A. The above is the case where the subfield b7 is divided equally, but the same applies to the case where two or more subfields are divided. FIG.
In this embodiment, only the subfield b7 is divided, and in the embodiment shown in FIG. 8, only b6 and b7 are divided. However, other subfields may be divided. The selection of the field to be divided and the arrangement of the display time regions are determined in consideration of the simplicity of the device configuration and the effect of improving the disturbance of gradation display.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to the above embodiments. Also,
The present invention includes a case where the direction of the time axis in the subfield arrangement of FIGS. 7 and 8 is reversed. In addition, as a display device according to the present invention, a gas discharge television device using a gas discharge light emitting element is representative, but the present invention is not limited to this.

[0034]

According to the present invention, the disturbance of the gradation can be improved without lowering the brightness of the image.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a circuit configuration for an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration example of a gas discharge panel used in an embodiment of the present invention.

FIG. 4 is a sectional view of a light emitting device of a gas discharge panel used in an embodiment of the present invention.

FIG. 5 is a voltage waveform chart for explaining the operation of the light emitting device shown in FIG.

FIG. 6 is an enlarged view showing one field of FIG. 1;

FIG. 7 is a diagram illustrating another example of means for suppressing disturbance of gradation.

FIG. 8 is a diagram showing another example of means for suppressing disturbance of gradation.

FIG. 9 is a diagram showing another example of a means for suppressing disturbance of gradation.

FIG. 10 is a diagram illustrating the operation of the arithmetic circuit of FIG. 9;

FIG. 11 is a diagram showing a conventional example of gradation display.

FIG. 12 is a diagram showing another conventional example of gradation display.

FIG. 13 is a diagram showing a measurement result example of a critical fusion period.

[Explanation of symbols]

 1: A / D converter, 2: Frame memory, 3: Gas discharge panel, 4: Counter, 5, 6, 7, ROM, 8, 11, 13, 14, 17, 18 ... Shift register, 9, 10, 15, 16, 19, 20: driver, 21: substrate, 22: cathode, 23: auxiliary anode, 24: display anode, 25: display discharge space, 26: phosphor, 27: auxiliary discharge space, 28: face plate, Reference numeral 30 denotes a discharge cell (light emitting element), 31 denotes a third electrode lead, 32 denotes a first electrode lead, 33 denotes a second electrode lead, 91 and 92 denotes a field memory, and 93 denotes an arithmetic circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mutsumi Suzuki 1-280 Higashi Koigabo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (3)

[Claims] 1. A display device for displaying an image having a gradation by causing a matrix panel to emit light by a subfield, a memory means for holding an image input signal, and the matrix panel based on 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 first panel section, and the matrix panel based on a second signal read from the memory means A second drive signal output means for forming and outputting a second drive signal for driving a first electrode of the second panel section, and a second electrode of each of the first and second panel sections. A sub-field which is weighted by the number of display pulses and is used for forming a gradation level of an image within a partial period of the field. In this case, the interval between the start of application of the display pulse of the first subfield in the preceding field and the start of application of the display pulse in the last subfield of the subsequent field is determined based on the subfield arrangement signal that is equal to or less than the critical fusion cycle. Third drive signal output means for forming and outputting a third drive signal for causing the matrix panel to emit light; and in each of the first and second panel portions, a drive state of the first electrode for each subfield. The light emission corresponding to the number of the display pulses based on the driving of the second electrode is controlled, and a grayscale image corresponding to the controlled light emission is displayed on the first and second panel units. A display device, comprising: a matrix panel that forms an entire image. 2. A display device for displaying an image having a gradation by causing a matrix panel to emit light by a subfield, comprising: memory means for holding an image input signal; and the matrix panel based on 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 first panel section, and the matrix panel based on a second signal read from the memory means A second drive signal output means for forming and outputting a second drive signal for driving a first electrode of the second panel section, and a second electrode of each of the first and second panel sections. , Which is weighted by the number of display pulses and includes six or more subfields as all subfields used for forming a gradation level of an image. Critical fusion of the interval between the display pulse application start time of the first subfield in the preceding field and the display pulse application start time of the last subfield in the subsequent field in adjacent fields A third drive signal output unit for forming and outputting a third drive signal for causing the matrix panel to emit light based on the subfield arrangement signal having a period equal to or less than the period; and in each of the first and second panel units, Further, the light emission corresponding to the number of the display pulses based on the drive of the second electrode is controlled by the drive state of the first electrode, and the gradation image corresponding to the controlled light emission is displayed on the second electrode. 1. A display device, comprising: a matrix panel for displaying on a second panel unit to form an entire image. 3. A display device for displaying an image having a gradation by causing a matrix panel to emit light by a subfield. A memory means for holding an image input signal; and the matrix panel based on 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 first panel section, and the matrix panel based on a second signal read from the memory means A second drive signal output means for forming and outputting a second drive signal for driving a first electrode of the second panel section, and a second electrode of each of the first and second panel sections. A sub-field which is weighted by the number of display pulses and is used for forming a gradation level of an image within a partial period of the field. Field, the interval between the start of the display pulse application of the first subfield in the preceding field and the start of the display pulse application of the last subfield in the subsequent field is approximately 2
A third drive signal output means for forming and outputting a third drive signal for causing the matrix panel to emit light based on the subfield arrangement signal of 0 ms or less; and in each of the first and second panel sections, Further, the light emission corresponding to the number of the display pulses based on the drive of the second electrode is controlled by the drive state of the first electrode, and the gradation image corresponding to the controlled light emission is displayed on the second electrode. 1. A display device, comprising: a matrix panel for displaying on a second panel unit to form an entire image.