JP2900744B2 - Halftone image display method for matrix type display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a matrix type display panel (hereinafter simply referred to as a display panel) such as a plasma display panel (hereinafter simply referred to as a PDP) or a liquid crystal display panel (hereinafter simply referred to as an LCD). In the above, one screen display period (for example, one frame display period or one field display period) of each pixel is time-divided into a display period of a bit number N (N is an integer of 2 or more) corresponding to a display gradation, and this N The present invention relates to a method of displaying a halftone image by weighting each divided display period according to each bit.

[0002]

2. Description of the Related Art Conventionally, this kind of halftone image display method has been performed as follows. That is, as shown in FIG. 3, a video signal input to the video signal input terminal 10 is converted into a digital signal by an A / D (analog / digital) conversion circuit 12, and is converted into a digital signal for a predetermined period (for example, 1/30 of one frame period). Second or 1/60 second), and alternately writes the data into the frame memories 14 and 16, and checks whether the image data is alternately read from the frame memories 14 and 16 .
Bit data displayed by the bit selection circuit 18
Are sequentially selected and supplied to the X driver 20.

[0003] A synchronizing signal separating circuit 22 separates a synchronizing signal (for example, a horizontal synchronizing signal and a vertical synchronizing signal) from a video signal, and a timing signal output circuit 24 is based on the synchronizing signal from the synchronizing signal separating circuit 22. Then, predetermined timing signals are output to the A / D conversion circuit 12, the frame memories 14, 16, the bit selection circuit 18, the X driver 20, and the Y driver 26.

The X and Y drivers 20 and 26 are PDP or L
A matrix type display panel formed of a CD (for example, a dot matrix type display panel,
Pulse signals for erasing, writing, addressing, scanning, sustaining, and the like are output to a display panel 28 and displayed in a matrix.
For example, in the case of 8-bit gray scale (256 gray scale) display,
For each pixel of the display panel 28, as shown in FIG. 4, one frame display period 1 as one screen display period
F is the eight sub-field periods S as divided display periods
The time division is performed into F1, SF2, SF3,..., SF8.

[0005] Each subfield period SF1, SF2, S
F3,..., SF8 are further added to the address period AP.
And time division into display periods SP, and each subfield period SF
In the display period SP of 1, SF2, SF3, ..., SF8,
A weight of 1: 2: 4:... 128 is weighted. For example, if the number of display pulses (sustain pulses) having a unit weight is two, the subfield periods SF1, SF2, S
The display pulse numbers of F3,..., SF8 are 2, 4, 8,.
256. Further, each sub-field period SF1, S
The address period AP of F2, SF3,..., SF8 is fixed (for example, 1.5 ms) regardless of the subfield periods SF1, SF2, SF3,.

Then, eight sub-field periods SF
In the address period AP for each of 1, SF2,..., SF8, writing is first performed over the entire surface of the display panel 28, and then erasure discharge is performed in accordance with display data to address. In the display period SP following this address, the subfield periods SF1, SF2,
.., Display is performed based on the number of display pulses weighted for each SF8.

Therefore, eight subfield periods S
A predetermined subfield period (for example, SF1 and SF2) from among the divided display periods of F1, SF2, SF3,.
And SF3), it is possible to perform a gradation display corresponding to the 256 gradations (for example, the eighth gradation display among the 256 gradation displays).

[0008]

However, in the conventional halftone image display method shown in FIG. 4, the eight subfield periods SF1 and SF8 time-divided for halftone image display are used.
SF2, SF3,...
4,..., 128 in an ascending order, if the image is bright, as shown in FIG. 5A, all the subfield periods (for example, SF1,
SF2, SF3,..., SF8) are not a problem because they are the lighting display period. However, when the image is dark, as shown in FIG. Since only the four sub-field periods (for example, SF1, SF2, SF3, SF4) are the lighting display period, there is a problem that flicker is likely to occur.

That is, when an image as shown in FIG. 5B is dark, the first continuous sub-field of eight sub-field periods SF1, SF2, SF3,..., SF8 in one frame display period 1F. Field period (for example, SF
1, SF2, SF3, and SF4) constitute the lighting display period, and thus a part (16/25) of one frame display period 1F.
This is because only 5) is lit and displayed, and most (240/255) are not lit and displayed. In other words, this is because the apparent lighting display frequency decreases (the distribution of the lighting driving frequency is shifted to a lower side).

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and prevents an apparent lighting display frequency from lowering even when an image is dark so that flicker hardly occurs.
It is an object of the present invention to provide a halftone image display method for a display panel.

[0011]

According to the present invention, one screen display period for each pixel of a display panel is time-divided into a display period of a bit number N (N is an integer of 2 or more) corresponding to a display gradation, In the method of displaying a halftone image by weighting each of the N divided display periods according to each bit, a time-series arrangement of the N divided display periods is
One by one from weight ascending order and descending order
It is characterized in that it is taken out and arranged in order .

[0012]

One screen display period (for example, one frame display period) for each pixel of the display panel is time-divided into a display period of N bits corresponding to the display gradation, and the N divided display periods (for example, (Field period) is weighted corresponding to each bit. Therefore, by selecting a predetermined number of divided display periods from the N divided display periods, N-bit (2 to the N-th power) gradation display is performed.

At this time, the time-series arrangement of the N divided display periods is sequentially changed from the ascending order to the descending order of the weighting by one.
Since the arrangement is made so as to be taken out one by one and arranged in order, it is possible to prevent the divided display periods with small weights from being concentrated in chronological order. Therefore, even if a dark image is displayed by selecting only the divided display period with a small weight,
The lighting display distribution within one screen display period is dispersed without being concentrated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for displaying a halftone image on a display panel according to the present invention will be described below with reference to FIGS. 1, 2 and 3. FIG. For convenience of explanation, a case will be described in which the method of the present invention is used to display an 8-bit gray scale (256 gray scales) on the display device of FIG. That is, a case where a halftone image of a video signal is displayed in 8-bit gray scale for each pixel of the display panel 28 in FIG. 3 will be described. At this time, for each pixel of the display panel 28, FIG.
, One frame display period 1F as one screen display period is time-divided into eight subfield periods SF1, SF2, SF3,..., SF8 as divided display periods.

Each subfield period SF1, SF2, S
F3,..., SF8, and the address period A
P and a display period SP, and each subfield period S
F1, SF2, SF3, SF4, SF5, SF6, SF
7, in the display period SP of SF8, 1: 128: 2: 6
A weight ratio of 4: 4: 32: 8: 16 is assigned. That is, a time-series array is obtained by sequentially taking out one by one from the ascending weighted arrays 1, 2, 4, and 8 and the descending weighted arrays 128, 64, 32, and 16 one by one. 1, which is an ascending sequence of weights shown in
., 128 are clearly different from the conventional example.

Each subfield period SF1, SF2, S
The address period AP of F3,..., SF8 is the same as the conventional example, and the subfield periods SF1, SF2, SF3,.
It is fixed (for example, 1.5 ms) regardless of SF8 and is determined by the display panel 28.

Then, eight sub-field periods SF
In the address period AP for each of 1, SF2,..., SF8, first, writing is performed over the entire surface of the display panel 28, and then erasure discharge is performed in accordance with display data to address. In the display period SP following this address, the subfield periods SF1, SF2,
.., The number of display pulses (that is, sustain pulses) weighted for each SF8 is displayed. For example, if the unit of weighting is two display pulses (pulse period: 7.5 μs), the number of display pulses in the display period SP of SF1, SF2,..., SF8 is 2 (1 × 2), 256 (128 × 2). ,
.., 32 (16 × 2).

Therefore, eight sub-field periods S
By selecting a predetermined subfield period (for example, SF1, SF2, and SF3) from among F1, SF2, SF3,..., SF8, a corresponding gray scale display among 256 gray scales (for example, 256-step gray scale display) ( 8th gradation display).

For this reason, as shown in FIG. 2A, the lighting display distribution when the image is bright is the first frame display period.
, Second frame display period,..., All subfield periods SF1, SF2, SF3,..., SF8 within that frame display period are lighting display periods. No.

The display distribution when the image is dark is shown in FIG.
As shown in the (b), the first frame display period, the second full
In each of the frame display periods of the frame display period,... , Only the four subfield periods SF1, SF3, SF5, and SF7 with a small weight in the frame display period are the lighting display periods.
1, SF3, SF5, and SF7 are not concentrated as in the conventional example, but are dispersed as shown in the figure, so that the apparent lighting display frequency does not decrease and is unlikely to cause flicker.

That is, when the image is dark as shown in FIG. 2B, the weights among the eight subfield periods SF1, SF2, SF3,... Only the four subfield periods SF1, SF3, SF5, and SF7 as small as 4, 8 are the lighting display periods, but since these lighting display periods are not concentrated but dispersed, the apparent lighting display frequency decreases. Because it does not.

In the above embodiment, one screen display period (eg, one frame display period) is time-divided into eight display periods, and each time-division display period (eg, subfield period) is weighted corresponding to each bit. Thus, the method of displaying a halftone image in 8-bit grayscale (256 grayscale) has been described, but the present invention is not limited to this, and the number of bits N (N Is divided into two or more integer display periods, and the N divided display periods are weighted in accordance with each bit, whereby the method can be used for displaying a halftone image.

[0023]

As described above, the method for displaying a halftone image on a display panel according to the present invention has one pixel for each pixel.
The screen display period (for example, one frame display period) is time-divided into N display periods, and the N divided display periods (for example, subfield periods) are weighted according to each bit, and N-bit gradation display is performed. Is performed, the time-series array of the N divided display periods is arranged in an ascending order of weights and in a descending order.
An array that is taken out one by one from the array
Since the columns are arranged, it is possible to prevent the divided display periods having a small weight from being concentrated in chronological order.

[0024] Therefore, the weighting of small divided display periods (e.g. weighting ratio is 1,2,4,8 divided display period) even when displaying a dark image by selecting only one screen display period of each pixel Lighting display period is dispersed ,
It is possible to prevent the apparent lighting display frequency from lowering and to suppress flicker.

[Brief description of the drawings]

FIG. 1 illustrates one embodiment of a method for displaying a halftone image on a display panel according to the present invention, and illustrates a state in which one frame display period for each pixel is time-divided into eight weighted subfield periods. FIG.

FIGS. 2A and 2B are explanatory diagrams illustrating a time-series lighting display distribution state, in which FIG. 2A shows a bright image and FIG. 2B shows a dark image.

FIG. 3 is a schematic configuration diagram illustrating a general configuration of a display panel display device.

FIG. 4 is an explanatory diagram illustrating a state in which one frame display period for each pixel is time-divided into eight subfield periods in which weighting is performed in a conventional example.

5A and 5B are explanatory diagrams illustrating a time-series lighting display distribution state of a conventional example, where FIG. 5A shows a case of a bright image, and FIG.
Indicates a dark image.

[Explanation of symbols]

10: video signal input terminal, 12: A / D conversion circuit, 1
4, 16 ... frame memory, 18 ... bit selection circuit,
20 ... X driver, 22 ... Synchronous signal separation circuit, 24 ...
Timing signal output circuit, 26 ... Y driver, 28 ...
Display panel, 1F: one frame display period (one example of one screen display period), AP: address period, SP: display period, SF1 to SF8: subfield period (one example of divided display period).

Claims (1)

(57) [Claims] 1. A screen display period for each pixel of a matrix type display panel is time-divided into a display period of a bit number N (N is an integer of 2 or more) corresponding to a display gradation, and the N divided displays are performed. In a method of displaying a halftone image by performing weighting corresponding to each bit during a period,
The time series sequence of the N divided display periods, weighted Noboru
Take out one by one from the sequential array and the descending sequence one by one
A method of displaying a halftone image on a matrix type display panel, wherein the halftone image is arranged in a matrix.