JP2005167659A - Signal processor, plasma display and signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid flickering or burning which appears at a boundary of a picture display area and a black area when image sharpening is applied to a picture of a different size from a screen size. <P>SOLUTION: The range of a picture display area is determined from the result of detecting the existence of image signal components in input picture signals, and an image sharpening process is controlled to be applied within the range. This prevents the image sharpening process from being applied to the boundary of the picture display area and the black area, and hence prevents the flickering or the burning which appears at such a boundary. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a signal processing apparatus and method for performing signal processing on an input video signal in, for example, an image display apparatus, and a plasma display apparatus incorporating the signal processing apparatus.

In the current television broadcasting, content with an image size of 4: 3 and content with 16: 9 are mixedly broadcast.
In such a current situation, for example, in the case of content such as digital satellite broadcasting, when broadcasting video content with a conventional 4: 3 ratio, as shown in FIG. : 3 is broadcast with the video display area inserted.
In addition, when a content such as a movie is broadcast in the current television broadcasting, for example, as shown in FIG. 10B, an image that is further horizontally long (so-called Sinesco) in a 16: 9 image. Size image) may be inserted and broadcast.

On the other hand, some image display devices that display video content are configured to perform an image sharpening process for conspicuous outlines in the video to obtain an overall sharp image.
As represented by so-called sharpness processing, video signal processing is performed so as to obtain a sharper display image by enhancing a luminance difference in the image.

In the following patent documents, for example, techniques for preventing burn-in in a plasma display device are described.
JP 2001-268391 A

Here, when the broadcast content as shown in FIG. 10 is displayed on the image display device, the video as the content portion of the broadcast content is displayed on the display screen 7a as shown in the figure. A display area 70 and other black areas 71 are formed.
In such a state, when the above-described image sharpening process is performed, the process is performed so that the boundary portion between the video display area 70 and the black area 71 becomes more prominent.

The state at this time will be described with reference to FIG. 11. The state of the boundary portion on the display screen 7a when the sharpening process is not performed is based on the state of the luminance cross section shown in FIG. As can be seen, the edge is already standing. That is, since a large luminance difference is originally generated between the video display area 70 side and the black area 71, originally sharpening processing for this part is unnecessary.
When such an image sharpening process is performed as described above, the luminance difference at the boundary portion is further emphasized as shown in the luminance cross section of FIG. 11B. As shown in the figure, the display image 7a at this time is such that the edge portion on the video display area 70 side has a higher brightness than necessary, and the edge portion on the black area 71 side has a lower brightness. The contrast difference at the boundary becomes intense.

  Such a sharp contrast difference appears as a flickering of the display image, which causes a problem in that the user feels uncomfortable and the image quality of the display image is degraded.

At this time, especially in the plasma display device, it is known that the state is stored in the pixel if an image with such a large contrast difference is continuously displayed due to the structure of the display panel. This is a phenomenon called burn-in.
If burn-in occurs, that portion will appear as an afterimage on the display screen during the subsequent display, and this also causes further problems such as giving the user a sense of discomfort and degrading the image quality.

In view of the above problems, the present invention is configured as follows as an image display device.
That is, first, video signal processing means for performing at least image sharpening processing is provided as video signal processing for an input video signal.
Then, range determining means for determining the range of the video display area from the result of detecting the presence or absence of the image signal component in the input video signal for the video display area and the black area included in the video based on the input video signal And control means for performing control on the video signal processing means so that the image sharpening process is performed only within the range of the video display area determined by the range determination means. .

In the present invention, the plasma display device is configured as follows.
That is, as video signal processing for the input video signal, at least video signal processing means for performing image sharpening processing, and a video display area and a black area included in the video based on the input video signal are included in the input video signal. Range determining means for determining the range of the video display area from the result of detecting the presence or absence of an image signal component.
And a control means for performing control on the video signal processing means so that the image sharpening process is performed only within the range of the video display area determined by the range determination means, and the video A plasma display panel is provided as display means for obtaining a display image based on an input video signal subjected to video signal processing by the signal processing means.

Furthermore, in the present invention, the image display method is as follows.
That is, a range determination procedure for determining a range of the video display area from a result of detecting the presence or absence of an image signal component in the input video signal for a video display area and a black area included in a video based on the input video signal; The control procedure for performing control so that the image sharpening process is performed only within the range of the video display area determined by the range determination procedure is executed.

  According to the present invention, the image sharpening process is performed only within the video display area in the video.

As described above, according to the present invention, since the image sharpening process is performed only in the video display area in the video, the video display area and the black area are mixed in the video as described above. However, it is possible to prevent the contrast difference between these boundaries from becoming severe.
Depending on this, it is possible to prevent flickering or the like at the boundary between the video display area and the black area in the display image, so as not to give the user a sense of incongruity, and to prevent deterioration in image quality.

  In addition, in the plasma display device having such a signal processing device of the present invention, since image sharpening processing is performed, burn-in that was supposed to occur at the boundary between the video display region and the black region is prevented. In this case, it is possible to prevent a sense of incongruity and a decrease in image quality due to such flicker as described above, and to reduce a sense of incongruity and a decrease in image quality due to such image sticking.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
FIG. 1 shows a structure of a display panel 7 provided in an image display device in which a signal processing device according to an embodiment of the present invention is built. In the following, description will be continued with an example in which the image display device in which the signal processing device according to the embodiment is incorporated is the plasma display device 1.

  In this case, as the plasma display device 1, an AC type (AC type) is taken as an example. The display panel 7 shown in the figure has a surface discharge type structure with a three-electrode structure.

First, in FIG. 1, a transparent front glass substrate 101 is disposed on the forefront of the display panel 7 as shown. The sustain electrode X (102A) and the scan electrode Y (102B) are arranged on the back side of the front glass substrate 101.
The sustain electrode X (102A) and the scan electrode Y (102B) are arranged in parallel with a predetermined interval, for example, as illustrated. The pair of sustain electrode X (102A) and scan electrode Y (102B) form a line as one “row”. The sustain electrodes X (102A) and the scan electrodes Y (102B) are formed by combining a transparent conductive film 102a and a metal film (bus conductor) 102b, respectively.

  On the back side of the front glass substrate 101, the sustain electrode X and the scan electrode Y are arranged as described above, and a dielectric layer 103 made of, for example, low-melting glass is further arranged. A protective film 104 made of, eg, MgO is formed on the back side of the layer 103.

In addition, on the front side of the rear glass substrate 105, the data electrode D (107) is arranged in a direction orthogonal to the sustain electrode X and the scan electrode Y. The data electrodes form lines as “columns”. In addition, a partition wall 106 is formed between adjacent data electrodes D.
The phosphor layers 108R, 108G, and 108B of R, G, and B colors are sequentially arranged so as to cover the upper surface of the rear glass substrate on which the data electrodes D are disposed and the side walls of the partition walls 106 on both sides thereof. Formed as described above.

After having such a structure, the front side end of the partition wall 106 is actually combined so as to abut against the protective film 104. With such a structure, the discharge space 109 in which the phosphor layers 108R, 108G, and 108B are formed is formed. The discharge space 109 is evacuated and filled with a gas such as neon (Ne), xenon (Xe), or helium (He).
Then, in the discharge space 109 in which this gas is enclosed, a surface discharge is generated between the sustain electrode X and the scan electrode Y, and ultraviolet rays are emitted, and the phosphor layer 108 is excited by the ultraviolet rays to generate visible light. Display light is emitted.

FIG. 2 shows the configuration of the drive circuit system based on the structure of the display panel 7 described above.
For example, when the display panel 7 is viewed as a whole, the sustain electrodes X (102A) are arranged such that the electrodes X1 to Xn are horizontally arranged from the upper direction to the lower direction, and the scanning electrodes Y (102B) are similarly arranged from the upper direction to the lower direction. The electrodes Y1 to Yn are arranged horizontally in the direction. Then, one line in the “row” direction is formed by each set of [electrode X1, electrode Y1] [electrode X2, electrode Y2]... [Electrode Xn, electrode Yn].
Further, the data electrode D (107), for example, has data electrodes D1 to Dm arranged in the vertical direction from the left to the right to form a line in the “column” direction.
Then, each intersection of a row direction line composed of the pair of sustain electrodes X1 to Xn and scan electrodes Y1 to Yn and a column direction line as the data electrodes D1 to Dm is formed as one cell (display cell) 30. Will be.

  As used herein, the cell 30 refers to the structure portion of the display panel formed by the positions where the sustain electrode X, the scan electrode Y, and the data electrode D intersect as described above. Then, according to the structure of the display panel 7 shown in FIG. 1, the cell 30 has R according to the color of the phosphor layer 108 correspondingly arranged as shown in FIGS. 1 and 3. Cell 30R, G cell 30G, and B cell 30B. One pixel 31 capable of color expression is formed by a set of R, G, B cells 30R, 30G, 30B arranged adjacent to each other in the horizontal direction.

  Further, the sustain electrode driver 22, the scan electrode driver 23, and the data electrode driver 21 shown in FIG. 2 are connected to the above-described sustain electrodes X1 to Xn, sustain electrodes Y1 to Yn, and data electrodes D1 to Dm, respectively, according to FIG. Driving is performed based on the display driving timing described. As a result, a required image is displayed on the display panel 7 as described below.

Next, display driving for the display panel 7 having the above structure will be described.
In this embodiment, image display is performed by a so-called subfield method. In the subfield method, as shown in FIG. 4, a period of one field (= 16.7 ms) is divided into a plurality of subfields. In FIG. 4, one field period is divided into eight subfields SF1 to SF8.
Here, one subfield period corresponding to each of the subfields SF1 to SF8 includes a preliminary discharge period A, an address discharge period B, and a sustain discharge period C as shown in the figure. The operation during each period will be described later.

When one field period is divided into eight subfields, the relative ratio of luminance to be expressed by the subfields SF1 to SF8 is 1: 2: 4: 8: 16: 32: 64: 128. Set binary weights. Then, in accordance with the set weights, luminances to be expressed by the subfields SF1 to SF8 are set. This luminance setting is actually set by the number of sustain discharge pulses applied to the sustain electrode X and the scan electrode Y in the sustain discharge period C in order to generate a surface discharge.
Here, since the pulse output period when applying the sustain discharge pulse is constant, the number of sustain discharge pulses increases and the sustain discharge period C becomes longer as the luminance weight is increased. On the other hand, the lengths of the preliminary discharge period A and the write discharge period B are determined by the total number n of row-direction lines and are constant regardless of the luminance weight.
Depending on the combination of light emission / non-light emission using such subfields SF1 to SF8, 256 gradations can be expressed for each of the R, G, and B cells.

The waveform diagram of FIG. 5 shows the display drive timing in one subfield period.
First, the preliminary discharge period A, which is the first period in one subfield period, is a period for canceling the influence of the light emission state in the immediately preceding subfield period and obtaining stable address discharge characteristics in the subsequent address discharge period B. It is.
Therefore, during the preliminary discharge period A, a preliminary discharge pulse Pp with the potential Vp is simultaneously applied to the sustain electrodes X1 to Xn as shown in the figure. Due to the preliminary discharge pulse Pp, a strong surface discharge occurs, and a large amount of wall charges are accumulated in the dielectric layer 103. Thereafter, the scan electrodes Y1 to Y2 are simultaneously applied to the scan electrodes Y1 to Y2 as shown in the figure. By applying the erase pulse Ppe, the wall charges are erased and unnecessary charges are removed.

In the subsequent address discharge period B, addressing is performed in line order to set light emission / non-light emission for each cell 30 in this subfield period. That is, the write discharge period B is a period for selecting the cell 30 to emit light in one subfield period.
In the write discharge period B, first, the sustain electrode X is maintained at a ground potential (0 V) as shown in FIG. Since the scan base pulse is applied to the sustain electrode X in this manner, as will be described later, even if the data pulse Pd is applied to the data electrode D during this period, the data electrode D and the sustain electrode X are not affected. Discharge is prevented from occurring.

Under this state, a negative scan pulse Pw with the potential Vw is sequentially applied to the scan electrodes Y1 to Yn. In other words, the horizontal lines are selected by sequentially scanning from the top to the bottom, for example. Then, within the period in which the line selection is performed by applying the scanning pulse Pw, the potential Vd is applied to the data electrode D corresponding to the cell to emit light in the selected line among the data electrodes D1 to Dm. A positive data pulse Pd is applied.
In the selected horizontal line to which the scan pulse Pw is applied, in the cell 30 to which the data pulse Pd is applied, a counter discharge is generated between the scan electrode Y and the data electrode D to generate wall charges.
In addition, since the scan base pulse is applied to the sustain electrode X at this time as described above, the data pulse Pd is erased, and the sustain electrode X is interposed between the sustain electrode X and the data electrode D. No discharge occurs at this point.

The subsequent sustain discharge period C is a period for maintaining the light emission state for the cell 30 set to emit light by the addressing in the write discharge period B.
For this purpose, first, a sustain discharge pulse Ps having a predetermined pulse width with a negative potential Vs is simultaneously applied to the sustain electrodes X1 to Xn. After the sustain discharge pulse Ps is applied to the sustain electrodes X1 to Xn, the sustain discharge pulse Ps having a predetermined pulse width with the negative potential Vs is simultaneously applied to the scan electrodes Y1 to Yn. To do.
After the application of the sustain discharge pulse to the scan electrodes Y1 to Yn is completed, the sustain discharge pulse Ps is alternately applied to the sustain electrodes X1 to Xn and the scan electrodes Y1 to Yn in the same manner. Is done. At this time, the sustain discharge pulse applied to the scan electrode Y side is delayed in phase by, for example, 180 ° from the sustain discharge pulse applied to the sustain electrode X side.
Thus, each time the sustain discharge pulse Ps is applied, the sustain electrode X and the scan electrode are set in the cell set to emit light in the previous write discharge period B, that is, in the cell 30 in which the wall charges are accumulated. A surface discharge occurs with Y.

Here, the light emission operation in the display panel 7 will be described with reference to FIG. In this figure, in the display panel 7 having the structure according to the present embodiment, a portion corresponding to one cell 30 is shown in a sectional view. In this figure, the same parts as those in FIG.
As described above, in the cell 30 in which wall charges are accumulated by applying the data pulse Pd in the write discharge period B, the sustain discharge is alternately performed on the sustain electrode X and the scan electrode Y in the sustain discharge period C. Surface discharge occurs in response to the application of the pulse Ps. This surface discharge is a plasma discharge in which the gas sealed in the discharge space 109 is turned into a plasma state, and as a result, ultraviolet rays are radiated in the discharge space 109.
Visible light is radiated from the phosphor layer 108 in response to the irradiation of the ultraviolet rays. This visible light corresponds to the fact that the phosphor layer is actually one of the R phosphor layer 108R, the G phosphor layer 108G, and the B phosphor layer 108B. It will be emitted by the color.
Then, the visible light is reflected by the phosphor layer 108, passes through the protective film 104, the dielectric layer 103, and the front glass substrate 101, and is irradiated to the front side as display light. .

  As described above, each cell 30 is controlled to emit light in accordance with the principle described with reference to FIG. Then, such a lighting operation is performed by display driving by the subfield method described above with reference to FIGS. 4 and 5, so that each cell 30 has a 256 gradation range within one field period. The light emission is controlled so as to obtain a required luminance. That is, it is possible to display a color image with 256 gradations.

Next, FIG. 7 shows an internal configuration example of the plasma display device 1 including the display panel and the panel driving unit described above as display means and the signal processing device as the embodiment.
In this figure, only the part mainly related to the image display of the internal configuration of the plasma display device 1 is extracted and shown.
The signal processing apparatus according to the embodiment includes at least the video signal processing unit 3 and the system controller 5 shown in this figure.

  In FIG. 7, the video signal input to the plasma display device 1 is input to the video input unit 2 shown in the figure. The video input unit 2 supplies an input video signal to the video signal processing unit 3. Further, the video signal input to the video input unit 2 in this way is also supplied to the system controller 5 connected via the internal bus 10 shown in the figure as needed.

The video signal processing unit 3 executes various processes for image display based on the input video signal based on the control of the system controller 9 connected via the internal bus 10.
For example, the video signal processing unit 3 performs various video signal processing on the input video signal. As the video signal processing in this case, image sharpening processing is performed in order to obtain a sharper image by emphasizing the contour portion in the display image.
The image sharpening process referred to here is, for example, for the purpose of image sharpening other than the process of adjusting the gain of a certain high frequency component in the video signal, for example, as in general sharpness processing. This includes a wide range of processing for image sharpening, such as processing for replacing an input video signal.

  The video signal processing unit 3 also performs processing for obtaining display data by R, G, and B for image display on the display panel 7. The display data of R, G, B obtained in this way by the video signal processing unit 3 is supplied to the panel driving unit 4.

  In this case, the video signal processing unit 3 also detects a synchronization signal (horizontal synchronization signal / vertical synchronization signal) for the input video signal. The synchronization signal detected by the video signal processing unit 3 is supplied to the panel drive unit 4 shown in the figure. This synchronization signal is also supplied to the system controller 5 via the internal bus 10.

The panel drive unit 4 comprehensively shows a configuration for driving the display panel 7 including each of the electrode drivers (data electrode driver 21, sustain electrode driver 22, and scan electrode driver 23) shown in FIG. Yes.
The panel driving unit 4 performs the timing described with reference to FIG. 5 for each subfield period based on the luminance pattern information supplied from the video signal processing unit 3 and the synchronization signal (horizontal / vertical). Thus, the sustain electrodes X and the scan electrodes Y are driven.
Then, based on the R, G, B display data and the synchronization signal supplied from the video signal processing unit 3 as described above, a data signal is applied to the data electrodes D1 to Dm. Thus, addressing is performed for each horizontal line in the write discharge period B as described with reference to FIG.
At the same time, in one field period, the sustain discharge pulse is applied to the sustain electrode X based on the supplied luminance pattern information.
Such driving of each electrode by the panel driving unit 4 is executed for each field period, whereby an image based on the input video signal is displayed on the display panel 7.

The system controller 5 is, for example, a microcomputer including a CPU (Central Processing Unit), and performs overall control of the plasma display device 1.
The system controller 5 includes a ROM (Read Only Memory) 8 and a RAM (Random Access Memory) 9 as shown.
The RAM 9 is used as a work area for the system controller 5.

The ROM 8 stores various programs and setting data necessary for the system controller 5 to control each unit.
Particularly in the case of this example, the ROM 8 stores a program for causing the system controller 5 to execute processing operations according to this example shown in FIGS.

In addition, the system controller 5 includes an operation input unit 6 illustrated as a user interface for a user to give various operation instructions to the plasma display device 1.
The operation input unit 6 includes various operation keys provided so as to be exposed to the outside of the casing of the plasma display device 1, for example. The operation input unit 6 supplies an operation signal corresponding to the operation on these operation keys to the system controller 5. The system controller 5 performs necessary control processing according to the operation signal supplied in this way.
As such an operation input unit 6, a user interface using a remote controller may be employed.

Here, in the plasma display device 1 of this example shown in FIG. 7, the image sharpening process is performed in the video signal processing unit 3 as described above, but the image sharpening process is performed in this way. In the image display device, when an image in which the video display area 70 and the black area 71 are mixed as shown in FIG. 10 is input, the contrast difference between these boundaries becomes excessive and flickers. And so on.
As described above, when such a strong contrast difference occurs, in the plasma display device 1 as in this example, such a contrast difference on the display panel 7 is There is a possibility that image sticking may occur. In this case, both of the above flicker and such image sticking become a problem.

Therefore, in the present embodiment, control is performed so that image sharpening processing is not performed at the boundary between the video display area 70 and the black area 71 as shown in FIG.
Specifically, the range of the video display area as described above is detected from the input video signal. Then, the video signal processing unit 3 is controlled so that the image sharpening process is performed only within the detected range.
As a result, the image display area 70 to be sharpened can be normally performed, and the sharpening process is not performed on the boundary portion between the image display area 70 and the black area 71. It becomes possible to. That is, since it is possible not to perform this for the boundary portion that does not require sharpening as described above, it is possible to prevent flickering at this boundary portion and to prevent the occurrence of burn-in. .

  In this example, when the video display area is referred to as described above, it refers to a display area in the display image where the video as the content content is shown, and the black area is the display area in the display image. It is assumed that the black portion other than the video display area is indicated.

Processing operations to be performed by the system controller 5 shown in FIG. 7 in realizing the above-described operation as the present example will be described with reference to the flowcharts shown in FIGS.
The processing operations shown in FIGS. 8 and 9 are performed by the system controller 5 based on a program stored in the ROM 8 shown in FIG.
Further, the processing operation shown in this figure is performed for a predetermined time set in advance so as to be able to cope with the case where the video display area 70 appears in a different pattern as shown in FIGS. 10 (a) and 10 (b). The explanation will be continued on the premise that it is performed every other time.

  First, in FIG. 8, the system controller 5 starts input of a video signal by the processing of step S101 shown in the figure. That is, input of the input video signal obtained in the video input unit 2 via the internal bus 10 is started.

In subsequent step S102, detection of the presence or absence of an image signal component for each horizontal line is started.
As the processing in step S102, the image data obtained in the input video signal is determined for the presence or absence of an image signal component for each horizontal line of data. For example, if only the black level component is obtained in the data for one horizontal line, it is determined that there is no image signal component. In other cases, it is determined that there is an image signal component.

In step S103, determination processing is performed as to whether an image signal component has been detected.
That is, it is determined whether or not a horizontal line having an image signal component is detected by the detection process started in step S102.
In step S103, if a horizontal line that has an image signal component is not detected and a negative result is obtained, for example, as shown in step S110, the display image in this case is determined to be an all-black image. Then, the processing operation is finished. In other words, the fact that no image signal component is detected in any horizontal line data in the image data means that the display image in this case is very likely to be an all-black image, so the processing operation is terminated accordingly. I am going to do it.

  For confirmation, it is assumed that the processing operation shown in this figure is executed at predetermined intervals as described above. For example, it is assumed that this is an all black image. Even when the processing is completed, the detection processing for the presence / absence of the image signal component as described above is performed again after a predetermined time. That is, even when a video signal including an image signal component is input later, the detection of the video display area 70 included therein is performed again.

On the other hand, if a positive result is obtained when a horizontal line that has an image signal component is detected in step S103, the process proceeds to step S104, and the detected horizontal line is set as a video start position in the vertical direction. Remember.
That is, the fact that the image signal component is detected in the horizontal line can be considered as the horizontal line being the start position of the video display area 70 in the vertical direction.

In subsequent step S105, it is determined whether or not a horizontal line having no image signal component is detected by the detection process started in step S102.
If a positive result is obtained assuming that a horizontal line having no image signal component is detected in step S105, the line immediately before the detected horizontal line is set as a video start end in the vertical direction in step S106. A process for storing is executed.
That is, in this case, since the detected horizontal line is already at the black level, the previous horizontal line is stored as the end position in the vertical direction of the video display area 70.
After the process of step S108 is executed, the process proceeds to the next step S109 shown in FIG.

If a negative result is obtained in step S105 that a horizontal line having no image signal component has not been detected, the process proceeds to step S107 as shown to determine whether the horizontal line has ended. The discrimination process is performed. That is, it is determined whether or not the detection process in step S102 for the last horizontal line in the input image data is completed.
If it is determined in step S107 that the horizontal line has not ended yet, the process proceeds to step S105, and the discrimination process for the line having no image signal component is executed again. That is, depending on the processing from step S105 to step S107, a loop for monitoring either detection of a line without an image signal component or end of a horizontal line is formed.
If it is determined in step S107 that the horizontal line has ended, the process proceeds to step S108, and the final horizontal line is stored as the video start position in the vertical direction.
Even when this step S108 is executed, the process proceeds to step S109 shown in FIG.

In FIG. 9, in step S109, detection of the presence / absence of an image signal component for each vertical column is started.
That is, in addition to the start position and end position in the vertical direction of the video display area 70 in the image data detected by the processing shown in FIG. 8, the detection of the start position and end position in the horizontal direction is subsequently started. Is.
As the detection process started in step S109, for example, for image data held in a frame memory not shown in FIG. 7, the presence or absence of an image signal component may be determined for each vertical column.

In step S111, it is determined whether or not an image signal component has been detected.
That is, it is determined whether or not a vertical column having an image signal component is detected by the detection process started by the process of step S109.
If an affirmative result is obtained in step S111 that a column having an image signal component is detected, the process proceeds to step S112, and the process for storing the detected vertical column as a horizontal image start position is performed. Execute.
That is, this means that the start position in the horizontal direction of the screen of the video display area 70 formed in the image data is detected.

Note that in step S111, if a negative result is obtained on the assumption that a column having an image signal component is not detected, the image signal component is detected in the previous frame image by the processing of FIG. Nevertheless, the image signal component is not detected in the image data of the next frame where the processing shown in FIG. 9 is started.
In response to such a situation, for example, the process proceeds to step S102 in FIG. 8 as shown in the figure, and the determination process for the presence or absence of the image signal component for each horizontal line is performed again. That is, in this case, the range detection of the video display area 70 is performed again from the next frame.

After the image start position in the horizontal direction is stored by the processing in step S112 described above, in step S113, determination processing is performed as to whether or not a column having no image signal component has been detected.
Also in this case, when an affirmative result is obtained on the assumption that a column having no image signal component is detected, the column immediately preceding the vertical column detected in this manner is used as in the case of the previous step S105. A process of storing the image start position in the horizontal direction is executed (step S114).

If a negative result is obtained in step S113 that a column having no image signal component is not detected, the process proceeds to step S115 to determine whether or not the vertical column has ended. If it is determined in step S115 that the vertical column has not yet ended, the process proceeds to step S113, and the determination process for the column having no image signal component is performed again.
If a positive result is obtained in step S115 that the vertical column has ended, a process of storing the last column as the video end position in the horizontal direction is executed in step S116.

  By executing the processing of step S114 or S116, the end position in the horizontal direction of the screen of the video display area 70 formed in the image data is detected.

In the subsequent step S117, the range of the video display area 70 is determined from the stored information of the video start / end positions in the horizontal and vertical directions of the screen.
That is, the image start position in the screen vertical direction stored in step S104 shown in FIG. 8, the image end position in the screen vertical direction stored in step S105 or S108 in FIG. 8, and step S112 described above. The range of the video display area 70 in the image data is determined based on the information on the video start position in the horizontal direction stored in step S1 and the information on the video end position in the horizontal direction stored in step S116. .

In step S118, the video signal processing unit 3 shown in FIG. 7 is controlled so that the image sharpening process is performed only within the determined range.
That is, as the processing of this step S118, for example, the range information determined in this way is set to the video signal processing unit 3 as information on the target range of the sharpening process, and the video display in the input image is performed. The sharpening process is performed only for the area 70.

As described above, in the present embodiment, the image sharpening process is performed only within the range of the video display area 70 where the video as the content portion is displayed. As shown in FIG. 10, when the video display area 70 and the black area 71 are mixed, it is possible to prevent the sharpening process from being performed on the entire screen.
According to this, this can be normally performed for the video display area 70 to be sharpened, and the boundary between the video display area 70 and the black area 71 is sharpened. It becomes possible not to perform processing.

  As described above, when the sharpening process is not performed on the boundary portion between the image display area 70 and the black area 71, the boundary is supposed to occur when the sharpening process is performed on the entire screen. It is possible to prevent flickering or the like in the portion, and it is possible to prevent the user from feeling uncomfortable or image quality degradation due to such flickering of the screen.

In this case, in particular, in the plasma display device, when the image sharpening process is performed on the entire screen, there is a high possibility that burn-in will occur at the boundary portion as described above. In the plasma display apparatus 1, since it is possible to prevent the boundary portion from being sharpened, it is possible to prevent such burn-in.
That is, depending on the plasma display device 1 of the present example, the user may experience discomfort and image quality degradation due to flicker as described above, and may also suppress such discomfort and image quality degradation due to image sticking. It will be.

In the present embodiment, as can be understood from the description of FIGS. 8 and 9, the image start / end position in the vertical direction of the screen is detected, and then the image in the horizontal direction of the screen is detected in the next frame. The case where the start / end positions are detected is taken as an example.
However, as a method for detecting the range of the video display area 70, for example, such detection of the start / end positions in the horizontal and vertical directions is simultaneously performed on image data held in a frame memory or the like. Other methods may be used.

  In the embodiment, the range of the video display area 70 is determined by detecting the video start / end positions over a plurality of frames and taking the average of the video start / end positions obtained as a result. A configuration for preventing erroneous detection of the range may be adopted.

In the embodiments, the signal processing apparatus and the method of the present invention are applied to the plasma display apparatus 1. However, the present invention can be suitably applied to other image display apparatuses. .
In addition, such a signal processing apparatus and method of the present invention can be applied to other image display apparatuses that may cause burn-in in a portion having a large contrast difference in a display image, such as a CRT (Cathode Ray Tube) display apparatus. If applied, it is possible to obtain a burn-in suppression effect when an image in which the video display area 70 and the black area 71 are mixed is displayed as in the plasma display device 1 of the present example.

It is a perspective view which shows the structure of the display panel of the plasma display apparatus in which the signal processing apparatus as embodiment of this invention is incorporated. It is a figure which shows the structure of the said plasma display apparatus with an electrode driver and an electrode. It is a figure which shows the relationship between the R, G, B cell in a display panel of the said plasma display apparatus, and a pixel. It is a figure which shows the example of the subfield pattern applied in embodiment. It is a timing chart (waveform diagram) showing an example of electrode drive (voltage application) timing in the subfield method. It is sectional drawing of a display panel for demonstrating the display principle in the said display panel. It is the block diagram which showed the internal structural example of the said plasma display apparatus. It is the flowchart which showed the processing operation as embodiment. Similarly, it is the flowchart which showed the processing operation as embodiment. It is the figure illustrated about the case where the image | video by the size different from a display screen size is displayed. It is the figure which showed the other example about the case where the image | video by the size different from a display screen size is displayed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Plasma display apparatus, 2 Video input part, 3 Video signal processing part, 4 Panel drive part, 5 System controller, 6 Operation input part, 7 Display panel, 8 ROM, 9 RAM, 10 Internal bus

Claims (3)

Video signal processing means for performing at least image sharpening processing as video signal processing for the input video signal;
Range determining means for determining the range of the video display area from the result of detecting the presence or absence of an image signal component in the input video signal for the video display area and the black area included in the video based on the input video signal;
Control means for performing control on the video signal processing means so that the image sharpening process is performed only within the range of the video display area determined by the range determination means;
A signal processing apparatus comprising: Video signal processing means for performing at least image sharpening processing as video signal processing for the input video signal;
Range determining means for determining the range of the video display area from the result of detecting the presence or absence of an image signal component in the input video signal for the video display area and the black area included in the video based on the input video signal;
Control means for performing control on the video signal processing means so that the image sharpening process is performed only within the range of the video display area determined by the range determining means, and
As a display means for obtaining a display image based on an input video signal subjected to video signal processing by the video signal processing means, a plasma display panel is provided,
A plasma display device. A range determination procedure for determining the range of the video display area from the result of detecting the presence or absence of an image signal component in the input video signal for the video display area and the black area included in the video based on the input video signal;
A control procedure for performing control so that image sharpening processing is performed only within the range of the video display area determined by the range determination procedure;
The signal processing method characterized by performing.

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