JP3158904B2 - Display panel image display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a display panel such as a plasma display panel (hereinafter simply referred to as PDP) or a liquid crystal display panel (hereinafter simply referred to as LCD). (1 frame screen) is divided into N (N is an integer of 2 or more) subfield screens corresponding to the display gradation, and the number of display pulses of each subfield screen is weighted corresponding to each bit, thereby obtaining a digital signal. The present invention relates to a method for displaying an N-bit halftone image of a video signal. Here, one field screen represents one screen displayed during one field period Tf (about (1/60) second), and one frame screen represents one frame period (about (1/30) second).
Second screen).

[0002]

2. Description of the Related Art When displaying a halftone image of a video signal (for example, a television signal) on a device having a large threshold characteristic such as a PDP, it is generally performed using a pulse modulation method in which the number of times of light emission is proportional to the video signal. ing. Specifically, the video signal is digitized, each field screen is divided by the number of bits to form N subfield screens, and each subfield screen emits light a number of times in proportion to the weight of the digital video signal. Key display is being performed. The display order of the subfield screen corresponding to each bit has been conventionally fixed.

[0003] For example, when displaying a halftone with 8 bits and 256 gradations, as shown in FIG. 9, one frame screen (one frame period (for example, about (1/30) second)) is displayed. Screen) to eight subfield screens [SF1]
To [SF8] (the screen displayed in the subfield periods SF1 to SF8), and each subfield period SF1,
.., SF8 is composed of an erasing period IP, an address period AP, and a display period SP, and the display period SP includes 1: 2: 4: 8:
..: Weighting is performed at a ratio of 128.

The IP and the AP are the same in each subfield period (for example, the sum of the IP and the AP is 1.5 ms). The display order of the subfield screen corresponding to each bit is, for example, [SF1], [SF1] as shown in the figure.
2], [SF3],..., [SF8].

[0005]

However, in the conventional video display method described above, the display order of the subfield screen is fixed (fixed). A false image occurs in the boundary area between the moving image and the background image, and this false image appears on a false contour portion that occurs in a portion where the brightness changes gradually, such as a human face, and a portion where the change in brightness is originally gradual However, there is a problem that a sharp change in brightness occurs (color generally changes in the case of color), and display quality is significantly impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a display image quality of a display panel (for example, a PDP) which performs gradation display by a subfield method by eliminating a false image generated when a moving image is followed by eyes. It is an object of the present invention to provide a method for displaying an image on a display panel, which can prevent the image quality from decreasing.

[0007]

According to a first aspect of the present invention, a unit display screen of a display panel is divided into N subfield screens corresponding to a display gradation of N bits (N is an integer of 2 or more). In a method of displaying a halftone video of a digital video signal by weighting the number of display pulses of each subfield screen corresponding to each bit, the amount and direction of motion in a unit display period of the video displayed on the display panel are determined. Detection is performed for each bit, and a motion correction amount is obtained based on the detected value and a division period ratio in a unit display period of each subfield screen, and the video of the corresponding subfield screen is detected by the motion correction amount in the detection direction. Characterized by moving to.

According to a second aspect of the present invention, in the first aspect of the present invention, the detection of the amount of motion and the direction of each bit in the unit display period of the video to be displayed is performed on the moving image and the background image on two continuous unit display screens. Is obtained from the signal of the subfield screen corresponding to.

[0009]

According to the first aspect of the present invention, a motion amount (for example, V.Tf) of a video displayed on a display panel (for example, PDP) in a unit display period (for example, one field period Tf).
And the direction (for example, the X direction) are detected for each bit, and the motion correction amount (for example, Ts / Tf) based on the detected value and the division period ratio (for example, Ts / Tf) in the unit display period of the subfield screen corresponding to each bit. For example, V · Ts) is obtained, the video of the corresponding subfield screen is moved in the detection direction (for example, the X direction) by the obtained motion correction amount, and the display position of each bit when the moving image is watched with eyes is observed. Eliminate misalignment and eliminate false images.

According to a second aspect of the present invention, in the first aspect of the present invention, the detection of the amount of motion and the direction of each bit in the unit display period of the video to be displayed is performed on the moving image and the background image on two consecutive unit display screens. , The amount of movement and the direction in the unit display period can be easily detected by obtaining from the signal of the subfield screen corresponding to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for displaying an image on a display panel according to the present invention will be described below with reference to FIGS. FIG. 1 shows a schematic configuration of a main part of a driving device for carrying out the method of the present invention. In FIG. 1, 10, 12,
Reference numeral 14 denotes first, second, and third frame memories each having a memory capacity capable of reading and writing a digital video signal for one frame screen.

The first, second and third frame memories 1
An input terminal 18 of a digital video signal is connected to the writing side of 0, 12, 14 via a first switching circuit 16 that is switched and controlled by a control circuit (not shown). The first, second, and third frame memories 10, 12,
A signal processing circuit 24 is connected to the read side of the signal processing circuit 14 via second and third switching circuits 20 and 22 that are switched and controlled by a control circuit (not shown). The output side of the signal processing circuit 24 is connected via a drive circuit 26 to a PDP (for example, a display capacity of 640) as an example of a display panel.
× 480 pixels of PDP) 28 are connected.

The first, second and third frame memories 1
0, 12, and 14 indicate memory control by a memory control circuit (not shown), and first, second, and third switching circuits 16, 2;
0, 22 to control the input terminal 18
The digital video signal is sequentially written for one frame screen of the input digital video signal, and the digital video signal is appropriately read from the frame memory for which the writing into the predetermined memory area has been completed.

For example, the first and second frame memories 10,
When sequentially writing the signals of two frame screens successive to 12 and then starting the writing of the signal of one frame screen subsequent to the third frame memory 14,
As shown in the figure, signals of two consecutive frame screens are read from the first and second frame memories 10 and 12 at appropriate timing and input to the signal processing circuit 24.

The signal processing circuit 24 determines the amount of motion and the direction (eg, X direction) in one field period Tf of the video to be displayed for each bit by using signals of a moving image and a background image in two consecutive frame screens. , And the detection value and the division period ratio (for example, Ts / T) in one field period Tf of the subfield screen corresponding to each bit.
f), and a signal corrected by moving the video of the corresponding subfield screen in the detection direction (for example, the X direction) by the obtained motion correction amount,
It is configured to output.

Next, an example in which the method of the present invention is carried out using the driving device shown in FIG. 1 will be described. A: First, there are two subfield screens, [SF1] and [SF2], which constitute a one-field screen, the display order of which is [SF1] and [SF2], and a dark background image (for example, luminance Subfield screen with weight 1 [SF
1]), a case where a bright moving image (for example, a subfield screen [SF2] having a luminance weight of 2) moves will be described with reference to FIGS.

For convenience of explanation, in FIGS. 2 and 3, the horizontal axis is time T, the vertical axis is distance X in the X direction (for example, the upward direction of the screen), and [SF1] to [SF2] of the subfield screen.
, The divided period in one field period Tf of the subfield screen [SF2] is Ts, and the moving image is X
It is assumed that the vehicle is moving at a speed V in the direction.

(A) The field screen displayed in one field period Tf is, of the subfield screens [SF1] and [SF2] constituting one field screen, firstly, the subfield screen [SF1] representing the background picture 30 Displayed, and then a subfield screen [SF
2] is displayed. Further, the subfield screen [SF
1] and [SF2], when one field period Tf elapses from the respective display times, the subfield screen [SF] is again displayed.
1] and [SF2] are displayed, and this is repeated thereafter.

Therefore, the amount by which the displayed image moves in the X direction during one field period Tf, that is, the amount of movement Xf is V · Tf (representing V × Tf) as shown in FIGS.
It is. In addition, as shown in FIG. 3, a viewer who follows the moving image 32 having the luminance of SF2 with eyes looks as if the rear end of the moving direction of the moving image 32 is moving along the thin line L1.
In addition, the leading end of the background image 30 having the brightness SF1 in contact with the moving image 32 appears to move along the thin line L2.
Since the display position of the boundary portion between the moving image 32 and the background image 30 is apparently shifted, the display portion corresponding to the oblique band portion 34 between the thin lines L1 and L2 looks brighter than the original luminance.

[0020] (b) Therefore, as shown in FIG. 2, T ₁
In T time ₃ has elapsed Ts period from the time, video 32 on the sub-field screen [SF2] is the distance from the original position shown by the dotted line to the position indicated by the solid line (i.e., motion correction amount X
If the correction is made so as to move in the X direction by s), the viewer who follows the moving image 32 on the subfield screen [SF2] does not shift the display position of the boundary portion between the moving image 32 and the background image 30. . The motion correction amount Xs can be obtained by multiplying the amount Xf of movement in the X direction during one field period Tf by the division period ratio (Ts / Tf), as shown in the following equation (1). Xs = Xf × (Ts / Tf) = V × Tf × (Ts / Tf) = V × Ts (1)

(C) The motion amount Xf and direction X of the moving image 32 during one field period Tf in the above equation (1) are detected by the signal processing circuit 24. That is, the signal processing circuit 2
4 is the first, second, and third frame memories 10, 12, 1
The motion amount Xf and the direction X of the moving image 32 during one field period Tf are detected based on digital video signals of two consecutive field screens sequentially read from two of the frame memories 10 and 12 out of four.

(D) Further, the signal processing circuit 24 determines whether the detected motion amount Xf is equal to one of the subfield screen [SF2].
The division period ratio (Ts / T) in the field period Tf
fs) to calculate Xs to calculate Xs. Then, the signal processing circuit 24 calculates the motion correction amount X
A signal corrected so that the moving image 32 moves in the detection direction X by s is output.

(E) The digital video signal output from the signal processing circuit 24 is input to the drive circuit 26 to drive and display the PDP 28. The PDP 28 displays a screen corresponding to a digital video signal without a false image. That is, P
The DP 28 displays the moving image 32 moving at a speed V in the X direction in the background image 30 without a false image.

As described above, on the subfield screen [SF2] shown in FIG.
2 is moved in the detection direction X, the apparent display position of the boundary between the moving image 32 and the background image 30 does not shift. As shown in FIGS. 3 and 4, this correction corresponds to a correction for removing an area 36 corresponding to the motion correction amount Xs from the front end portion of the background image 30 that is in contact with the moving image 32. A false image generated at the boundary between the moving image 32 and the moving image 32 is eliminated, and the change in brightness from the moving image 32 to the background image 30 is smoothed.

B: Secondly, the number of sub-field screens constituting one field screen is A except that the display order of the sub-field screens is [SF2] and [SF1] which are opposite to the order of A. A case where a bright moving image (sub-field screen [SF2] with a luminance weight of 2) moves in a dark background image (sub-field screen [SF1] with a luminance weight of 1) as in the case of FIG. 5 and FIG.

(A) As for the field screen displayed during one field period Tf, first of the subfield screens [SF1] and [SF2] constituting the one field screen, the subfield screen [SF2] representing the moving picture 32 is displayed. And
Next, a subfield screen [SF1] representing the background image 30
Is displayed. Further, the subfield screen [SF
2] and [SF1], when one field period Tf elapses from the respective display times, the subfield screen [SF] is again displayed.
2] and [SF1] are displayed, and this is repeated thereafter.

Accordingly, the amount by which the displayed image moves in the X direction during one field period Tf, that is, the amount of movement Xf is V · Tf (representing V × Tf) as shown in FIG. In addition, as shown in FIG. 5, a viewer who follows the moving image 32 with the luminance of SF2 looks like the rear end of the moving direction of the moving image 32 moving along the thin line L1. Further, the leading end of the background image 30 having the luminance of SF1 in contact with the moving image 32 appears to move along the thin line L2. Since the display position of the boundary between the moving image 32 and the background image 30 is apparently shifted, the oblique band-shaped portion 3 between the thin lines L1 and L2
The display portion corresponding to 8 looks darker than the original luminance.

(B) For this reason, if the moving image 32 on the subfield screen is corrected so as to move in the X direction by the motion correction amount Xs in the same manner as in the case of A, the moving image 32 on the subfield screen can be viewed. Video 3
The displacement of the display position at the boundary between the image 2 and the background image 30 is eliminated. In the case of A, the motion correction amount Xs can be obtained by multiplying the amount Xf of movement in the X direction during one field period Tf by the division period ratio (Ts / Tf).

(C) The motion amount Xf and the direction X of the moving image 32 are detected by the signal processing circuit 24 in the same manner as in the case A. Further, the signal processing circuit 24 calculates the above-described equation (1) using the detected amount of motion Xf and the divided period ratio (Ts / Tf) to calculate the motion correction amount Xs. Then, the signal processing circuit 24 outputs a signal corrected so that the moving image 32 is moved in the detection direction X by the movement correction amount Xs.

(D) The digital video signal output from the signal processing circuit 24 is input to the drive circuit 26 to drive and display the PDP 28. The PDP 28 displays a screen corresponding to a digital video signal without a false image. That is, P
The DP 28 displays the moving image 32 moving at a speed V in the X direction in the background image 30 without a false image.

As described above, on the predetermined subfield screen, the moving image 32 is detected by the motion correction amount Xs in the detection direction X.
Is corrected, the apparent display position of the boundary between the moving image 32 and the background image 30 does not shift. This correction is performed on the moving image 3 of the background image 30 as shown in FIGS.
A region 4 corresponding to the motion correction amount Xs is provided at the tip portion in contact with 2.
This correction corresponds to a correction of adding 0, and this correction eliminates a fake image generated at the boundary between the background image 30 and the moving image 32, and
, The change in brightness toward the background image 30 is smoothed.

C: Third, the number of subfield screens constituting one field screen is [SF1], [SF2],
[SF3] (different from A and B), and the display order of the subfield screen is [SF2], [S2
F3], [SF1], and a dark (eg, SF1, SF2 with a luminance weight of 1, 2) moving image 32a moves in a bright (eg, a SF3 with a luminance weight of 3) background image 30a. , FIG. 7 and FIG.

(A) The subfield screens [SF1], [SF2], and [SF3] constituting one field screen are
[SF2], [SF3], and [SF1] are displayed in this order. For a viewer who follows the moving image 32a whose luminance is SF1 + SF2, the rear end of the moving direction of the moving image 32a is indicated by a thin line L1.
It seems to move at a speed V along. Also, the tip of the background image 30a having the brightness of SF3 in contact with the moving image 32a is
It appears to move at the speed V along the thin line L2. Since the display position of the boundary portion between the moving image 32a and the background image 30a is apparently shifted, the display portion corresponding to the oblique strip portion 42 between L1 and L2 looks brighter than the original luminance.

(B) For this reason, similarly to the case A, if the moving image 32a on the subfield screen is corrected so as to move in the X direction by the motion correction amount Xs, the moving image 32a on the subfield screen can be visually recognized. The displacement of the display position of the boundary portion between the moving image 32a and the background image 30a disappears for the observer who follows. The motion correction amount Xs can be obtained by multiplying the amount Xf of movement in the X direction during one field period Tf by the division period ratio (Ts / Tf), as in the case of A.

(C) The motion amount Xf and the direction X of the moving image 32a are detected by the signal processing circuit 24 as in the case A. Further, the signal processing circuit 24 calculates the above-described equation (1) using the detected amount of motion Xf and the divided period ratio (Ts / Tf) to calculate the motion correction amount Xs. Then, the signal processing circuit 24 outputs a signal corrected so that the moving image 32a is moved in the detection direction X by the movement correction amount Xs.

(D) The digital video signal output from the signal processing circuit 24 is input to the drive circuit 26 to drive and display the PDP 28. The PDP 28 displays a screen corresponding to a digital video signal without a false image. That is, P
The DP 28 displays the moving image 32a moving at a speed V in the X direction in the background image 30a without a false image.

As described above, if the moving image 32a is moved in the detection direction X by the motion correction amount Xs on the predetermined subfield screen, the moving image 32a and the background image 30a
There is no apparent shift in the display position at the boundary of. This correction is performed, as shown in FIG. 7 and FIG.
Motion correction amount Xs of the tip portion in contact with the moving image 32a
The correction corresponds to a correction that removes the region 44 corresponding to, and this correction eliminates a false image generated at the boundary between the background image 30a and the moving image 32a, and smoothes the change in brightness from the moving image 32a toward the background image 30a.

In the above embodiment, N = 2 (A and B: when the moving picture is brighter than the background picture), 4-gradation display, or N = 3 (C: when the moving picture is darker than the background picture), 8 gradations Although the present invention is used in the case of display, the present invention is not limited to this, and when N is an integer of 2 or more (for example, N = 8
Of 256 gradations (8 bits)).

In the above-described embodiment, the present invention is used in a case where a fake image is generated in the rear part of the moving direction of the moving image. However, the present invention is not limited to this, and the fake image is a boundary between the moving image and the background image. It can be used for cases that occur in For example, the present invention can be applied to a case where a false image occurs in the front part of the moving direction of a moving image.

In the above embodiment, the unit display period (for example,
In order to easily detect the motion amount and direction of the video in one field period Tf), subfields corresponding to a moving image and a background image in two continuous unit display screens (for example, one field screen or one frame screen) From the screen signal, the motion amount and direction of the video for each bit are detected, but the present invention is not limited to this, and the video signal input for display on the display panel is detected for each bit. What is necessary is just to detect the motion amount and the direction of the video.

In the above embodiment, the display panel is P
The case where the present invention is used as DP has been described,
The present invention is not limited to this, and the present invention can be applied to a display panel (for example, LCD) other than the PDP.

[0042]

According to the first aspect of the present invention, in a display panel (for example, a PDP) which performs gradation display by a subfield method, a motion amount (for example, one field period Tf) of an image displayed on the display panel is displayed. For example, V · Tf) and direction (for example, X direction) are detected for each bit, and based on this detection value and the division period ratio (for example, Ts / Tf) in the unit display period of the subfield screen corresponding to each bit. Motion correction amount (for example, V
Ts) is obtained, and the video of the corresponding subfield screen is moved in the detection direction by the amount of the motion correction. The image quality can be improved by eliminating the false image generated at the boundary of the background image.

According to a second aspect of the present invention, in the first aspect of the present invention, the detection of the amount of motion and the detection of each bit of the direction in the unit display period of the video to be displayed is performed on the moving image and the background on two continuous unit display screens. Since it is determined from the signal of the subfield screen corresponding to the image, it is possible to easily detect the motion amount and the direction of the image in the unit display period.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a driving device for implementing a method of displaying an image on a display panel according to the present invention.

FIG. 2 is a view for explaining the operation of implementing the method of the present invention using the driving device of FIG. 1;
1] and [SF2], the display order is [SF1], [S
[F2] is an explanatory diagram illustrating an operation when a bright moving image ([SF2]) moves in the X direction in a dark background image ([SF1]) (case A in the detailed description).

FIG. 3 is an explanatory diagram for explaining the operation of FIG. 2 from another viewpoint.

FIG. 4 is an explanatory diagram for explaining the operation of FIG. 2 from another viewpoint.

FIG. 5 is a view for explaining the operation of implementing the method of the present invention using the driving device of FIG. 1;
1] and [SF2], the display order is [SF2], [S
F1] is an explanatory diagram illustrating an operation when a bright moving image ([SF2]) moves in the X direction in a dark background image ([SF1]) (case B in the detailed description).

FIG. 6 is an explanatory diagram for explaining the operation of FIG. 5 from another viewpoint.

FIG. 7 is a diagram for explaining the operation of implementing the method of the present invention using the driving device of FIG. 1;
1], [SF2] and [SF3], and the display order is [S
F2], [SF3], [SF1] and a dark moving image ([SF2] + [SF) in a bright background image ([SF3]).
1]) is an explanatory diagram for explaining the operation when (1)) moves in the X direction (case C in the detailed description).

FIG. 8 is an explanatory diagram for explaining the operation of FIG. 7 from another viewpoint.

FIG. 9 shows one frame period for displaying one field screen and a subfield period for displaying subfield screens constituting one field screen when displaying 256 gradations (8 bits) by a general subfield method. FIG.

[Explanation of symbols]

10, 12, 14 ... frame memory, 16, 20, 2
2 switching circuit, 18 input terminal, 24 signal processing circuit, 26 drive circuit, 28 PDP (plasma display panel), 30, 30a, background image, 32, 3
2a: moving images, 34, 38, 42: areas where false images occur, 36, 40, 44 ... correction areas to be deleted or added,
B: luminance, L1: a thin line representing the movement of the rear end of the moving direction of the moving image, L2: a thin line representing the movement of the leading end of the background image on the moving image side, SF1 to SF8: the subfield period or the luminance, SF1] - [SF8] ... subfields screen, T ... time, T _1, T ₂ ... time, Ts ... subfield division period, (corresponding to the unit display screen example of a unit display period) Tf ... 1 field period, Ts / Tf: divided period ratio in one field period, V: moving speed of moving image in X direction, X: moving direction or distance of moving image in one field period, Xf: moving amount of moving image in one field period, Xs: motion correction amount .

Claims (2)

(57) [Claims] 1. A unit display screen of a display panel is divided into N subfield screens corresponding to a display gradation of N bits (N is an integer of 2 or more). In the method of displaying a halftone video of a digital video signal by performing weighting corresponding to (i), a motion amount and a direction in a unit display period of a video displayed on the display panel are detected for each bit, and the detected value and A motion compensation amount is obtained based on a division period ratio in a unit display period of each subfield screen, and the image of the corresponding subfield screen is moved in the detection direction by the motion compensation amount. Panel image display method. 2. The detection of the amount of motion and the direction of each bit in a unit display period of a video to be displayed is obtained from signals of a subfield screen corresponding to a moving image and a background image in two continuous unit display screens. The method for displaying an image on a display panel according to claim 1.