JP2010002770A - Video signal processing apparatus, video signal processing method, program, and display device - Google Patents

Video signal processing apparatus, video signal processing method, program, and display device Download PDF

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JP2010002770A
JP2010002770A JP2008162486A JP2008162486A JP2010002770A JP 2010002770 A JP2010002770 A JP 2010002770A JP 2008162486 A JP2008162486 A JP 2008162486A JP 2008162486 A JP2008162486 A JP 2008162486A JP 2010002770 A JP2010002770 A JP 2010002770A
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video signal
correction
correction value
gain
display
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Masayuki Otawara
正幸 大田原
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Samsung Electronics Co Ltd
三星電子株式会社Samsung Electronics Co.,Ltd.
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Abstract

Video signal processing apparatus and video signal processing capable of controlling luminance based on an input video signal, preventing display failure due to voltage drop caused by common electrode resistance, and reducing power consumption A method, a program, and a display device are provided.
An average luminance calculation unit that divides a display screen into a plurality of divided regions and calculates an average luminance for each divided region based on an input video signal; and a display screen based on the average luminance for each divided region A correction center for determining a divided area where a voltage drop of a local common electrode may occur and setting a gain of a video signal corresponding to the determined divided area to a predetermined value or less that prevents the occurrence of a voltage drop A correction center setting unit that sets a position, a correction value setting unit that sets a correction value according to the display position of the display screen with the correction center position as a base point, and a gain adjustment unit that adjusts the gain of the video signal based on the correction value A video signal processing apparatus is provided.
[Selection] Figure 5

Description

  The present invention relates to a video signal processing device, a video signal processing method, a program, and a display device.

  In recent years, organic EL displays (also referred to as organic light emitting diode displays) or FEDs (Field Emission Displays) as display devices that replace CRT displays (Cathode Ray Tube displays). Various self-luminous display devices such as PDP (Plasma Display Panel) have been developed.

  In the development of various display devices as described above, it is a technical goal to achieve high image quality with low power consumption. Under such circumstances, techniques for improving image quality while reducing power consumption have been developed. As a technique for reducing power consumption by always lowering the luminance toward the edge of the screen when the video is displayed on the screen, the physical center point of the screen is always used as a base point.

Japanese Patent No. 3115727

  Among the self-luminous display devices, the organic EL display is a self-luminous display device utilizing an electroluminescence phenomenon (ElectroLuminescence). The organic EL display is superior in moving image characteristics, viewing angle characteristics, color reproducibility, and the like compared to a display device that requires a separate light source such as an LCD (Liquid Crystal Display). It is particularly attracting attention as a next-generation display device. Here, the electroluminescence phenomenon means that the electronic state of a substance (organic EL element) is changed from a ground state to an excited state by an electric field, and from an unstable excited state to a stable ground state. This is a phenomenon in which the energy of the difference is emitted as light when returning. In the following, problems in the prior art will be described by taking a display device including an organic EL element as a light emitting element, that is, an organic EL display, as an example, but it is not limited to an organic EL display. The following problems may also occur in non-self-emitting display devices such as LCDs that require a separate light source.

  When the display device includes an organic EL element as a light emitting element, each pixel constituting a display panel that displays an image on a display screen is arranged in a matrix (matrix), for example, and each pixel is an active matrix (active matrix). ) Method. When the display device includes an organic EL element as a light emitting element, each pixel includes, for example, a light emitting element and a drive transistor that is connected to the light emitting element and controls application of a light emission current to the light emitting element. FIG. 13 is an explanatory diagram schematically illustrating an example of a pixel circuit. Note that FIG. 13 illustrates an example in which the driving transistor is a p-channel transistor, but the present invention is not limited thereto.

  Referring to FIG. 13, the pixel circuit includes a light emitting element D1 whose cathode is connected to the ground GND, a driving transistor Tr1 connected to the anode and the power source of the light emitting element D1, respectively, and a gate terminal and a power source of the driving transistor Tr1. And a connected capacitor C1. Here, in a display panel having a pixel circuit as shown in FIG. 13, either the power supply side or the ground GND serves as a common electrode depending on the configuration of the pixel circuit and the type of transistor used in the pixel circuit. Fulfill. For example, when light is extracted from the cathode side of the light emitting element D1 in the pixel circuit shown in FIG. 13, the ground GND becomes a common electrode. In the above case, the ground GND is made of a transparent conductive material such as ITO (Indium Tin Oxide). Further, for example, when light is extracted from the anode side of the light emitting element D1 when the ground GND is used as a common electrode, the ground GND does not need to be transparent, and thus the ground GND is made of metal or the like. Hereinafter, for convenience of explanation, a case where the ground GND is a common electrode will be described as an example.

  Even when ITO is used as the common electrode or when metal or the like is used, a certain resistance value exists in the common electrode. Further, the resistance value exists in various places on the display panel as shown in FIG. 14, and generally the resistance value is larger in the central portion of the display panel than in the peripheral portion of the display panel. When the resistance value increases, the pixel circuit shown in FIG. 13 is equivalent to the case where the resistor Ro is inserted as shown in FIG. 15, for example. Here, FIG. 14 is an explanatory diagram schematically showing the resistance value generated in the common electrode of the display panel, and FIG. 15 schematically shows the pixel circuit when the resistance value of the resistance generated in the common electrode is large. It is explanatory drawing shown.

  When the pixel circuit shown in FIG. 13 is equivalent to the pixel circuit in which the resistor Ro is inserted as shown in FIG. 15, a voltage drop occurs in the resistor Ro. If the voltage drop generated in the resistor Ro becomes large, there is a risk that the voltage that should originally be applied to the light emitting element D1 cannot be maintained. In the above case, since a current for light emission is not normally applied to the light emitting element D1, for example, a display failure such as a decrease in luminance or non-light emission is caused. FIG. 16 is an explanatory diagram illustrating an example of a display defect caused by a voltage drop due to the resistance Ro existing in the common electrode. Here, FIG. 16 shows a display example in a case where an image showing white on the entire display screen (display panel), that is, an image having the maximum luminance (image of the maximum gradation) is displayed.

  As described above, the resistance value of the resistor Ro existing in the common electrode is larger in the central portion of the display panel than in the peripheral portion of the display panel. In addition, display defects due to the voltage drop as described above are likely to occur when the current flowing through the light emitting element is large (that is, when the luminance is high). Therefore, when an image having the maximum luminance is displayed on the entire display screen, for example, as shown in FIG. 16, the luminance of the central portion of the display screen is caused by the largest voltage drop in the central portion of the display screen. Decreases (an example of display failure). Further, when the display device includes an organic EL element as a light emitting element, for example, the characteristics of the light emitting elements corresponding to RGB are different. Therefore, even when pixels (sub-pixels) corresponding to RGB are located at the same position on the display screen, the degree of occurrence of display defects is not necessarily constant in pixels corresponding to RGB. In the above case, not only the luminance is reduced but also an unintended color may appear on the display screen.

  In the above, an example of a display defect when an image having the maximum luminance is displayed on the entire display screen is described, but the present invention is not limited thereto. For example, when the display device has a function of determining the load on the entire display screen based on the input video signal and limiting the brightness when the load on the entire display screen becomes large, when displaying on the entire screen Not necessarily. Further, depending on the input video signal, there is a possibility that the above-described display defect may occur in a place other than the central portion of the display panel.

  Also, where and how much the voltage drop occurs on the display screen depends on, for example, the size of the display panel, the material of the common electrode, the film pressure, the input video signal, and the like. For example, in a display panel having a size of 10 inches or more, a voltage drop of 1 V or more may occur in the central portion of the display panel. In the above case, depending on the configuration of the pixel circuit and the setting of the driving voltage for driving the pixel circuit, the above display defect may occur.

  As a method for preventing a display defect due to a voltage drop caused by the resistance of the common electrode (hereinafter sometimes referred to as “common electrode resistance Ro”), for example, a power supply voltage supplied to the pixel circuit is used. Increasing the height of the pixel circuit may provide a margin for the operation of the pixel circuit. However, when the power supply voltage is set high as described above, for example, this leads to an increase in power consumption in the display device. In addition, when the power supply voltage is set high as described above, for example, each pixel circuit of the display panel must be formed of an element that can withstand the power supply voltage, resulting in an increase in cost. Therefore, when the power supply voltage is set high as described above, various problems such as an increase in power consumption and an increase in cost can be achieved even if a display failure due to a voltage drop due to the resistance Ro of the common electrode can be prevented. Cause serious problems.

  In addition, a display device using a conventional technique (hereinafter, simply referred to as “conventional technique”) that lowers the luminance toward the edge of the screen from the physical center point of the display screen is input. Regardless of the video (or image) indicated by the video signal, the video signal is always processed so that the luminance decreases toward the edge of the screen from the physical center of the display screen. . Here, as described above, the voltage drop caused by the resistance Ro of the common electrode is likely to occur in the central portion of the display panel because the central portion of the display panel is larger than the peripheral portion of the display panel. However, since the apparatus using the conventional technology always processes the video signal so that the luminance decreases toward the edge of the screen from the physical center point of the display screen as a base point, This is equivalent to the fact that no countermeasure has been taken for the central portion of the display panel where a voltage drop due to the resistance Ro is likely to occur. Therefore, even if the conventional technique is used, it is not possible to prevent display failure due to a voltage drop caused by the common electrode resistance Ro that may occur in the central portion of the display panel.

  Further, in the above description, it has been described that the above-described display failure may occur in a place other than the central portion of the display panel. Even in the above case, a device using a conventional technique cannot always prevent a display defect due to a voltage drop caused by the resistance Ro of the common electrode.

  FIG. 17 is an explanatory diagram for explaining a problem in the apparatus using the conventional technique for reducing the luminance toward the edge of the screen from the physical center point of the display screen. Here, FIG. 17A shows a display screen that displays an image corresponding to a video signal, and an image in which a region A having a high luminance is positioned on the right side of the center of the display screen is displayed on the display screen. A displayed example is shown. That is, the region A indicates a region where a voltage drop due to the resistance Ro of the common electrode is likely to occur. FIG. 17B shows an example of video signal correction in an apparatus using a conventional technique that lowers the luminance toward the edge of the screen from the physical center point of the display screen. Here, FIG. 17B shows the relationship between the display position (Position) of the display screen shown in FIG. 17A and the target gain (Gain) after correction of the video signal. FIG. 17B is a diagram for explaining a problem of the conventional technique and for comparison with an embodiment of the present invention described later. Therefore, the invention according to the prior art described in, for example, the above-mentioned Patent Document 1 does not control the gain to the value shown in FIG. 17B, and an embodiment of the present invention described later is described in, for example, It goes without saying that the invention described in Document 1 is not used.

  As shown in FIG. 17B, the device using the conventional technique lowers the gain of the video signal input at the position P1 corresponding to the region A by q10. Here, the voltage drop due to the resistance Ro of the common electrode is likely to occur when the current flowing through the light emitting element is large (that is, when the luminance is high) as described above. In other words, it can be said that the voltage drop caused by the common electrode resistance Ro can be suppressed by lowering the gain of the video signal. However, since the apparatus using the conventional technology always processes the video signal so that the luminance decreases toward the edge of the screen from the physical center point of the display screen as a base point, It is not always possible to reduce the voltage drop caused by the resistor Ro to such an extent that display failure does not occur. Therefore, even if a conventional technique for lowering the luminance toward the screen edge from the physical center point of the display screen is used, it is possible to prevent a display failure due to a voltage drop caused by the resistance Ro of the common electrode. Not necessarily.

  Therefore, as described above, even if the conventional technique for lowering the luminance toward the edge of the screen from the physical center point of the display screen is used, display defects due to voltage drop caused by the resistance Ro of the common electrode are eliminated. It cannot be prevented.

  The present invention has been made in view of the above problems, and an object of the present invention is to display by a voltage drop caused by the resistance of the common electrode by controlling the luminance based on the input video signal. It is an object of the present invention to provide a new and improved video signal processing device, video signal processing method, program, and display device capable of preventing defects and reducing power consumption.

  In order to achieve the above object, according to a first aspect of the present invention, an average brightness for dividing a display screen into a plurality of divided areas and calculating an average brightness for each of the divided areas based on an input video signal. Based on the calculation unit and the average luminance for each of the divided areas, a divided area where a local common electrode voltage drop may occur in the display screen is determined, and the gain of the video signal corresponding to the determined divided area is determined. A correction center setting unit for setting a correction center position for setting the voltage drop to be equal to or less than a predetermined value that prevents the occurrence of the voltage drop, and a correction value corresponding to the display position of the display screen with the correction center position as a base point There is provided a video signal processing device including a correction value setting unit that performs and a gain adjustment unit that adjusts the gain of the video signal based on the correction value.

  With such a configuration, it is possible to control luminance based on an input video signal, to prevent display failure due to a voltage drop caused by the resistance of the common electrode, and to reduce power consumption.

  The correction value setting unit may set a correction value that attenuates the gain of the video signal toward the screen edge of the display screen, with the correction center position as a base point.

  With this configuration, it is possible to prevent display failure due to a voltage drop caused by the resistance of the common electrode and reduce power consumption while preventing deterioration in image quality.

  The correction value setting unit may change the gain attenuation rate of the video signal in accordance with a deviation amount of the correction center position with respect to a predetermined reference position.

  With this configuration, it is possible to prevent the luminance at one display screen end from being extremely lowered and to further improve the image quality.

  The correction value setting unit corresponds to the first correction center position when the correction center position set by the correction center setting unit changes from the first correction center position to the second correction center position. The correction value may be changed stepwise from the correction value to the correction value corresponding to the second correction center position.

  With this configuration, it is possible to prevent an abrupt change in luminance and further improve image quality.

  Further, the correction value setting unit further reduces the luminance of the video signal after adjustment in the gain adjustment unit as the average luminance is larger than the threshold based on the average luminance for each of the divided regions and a predetermined threshold. The correction value to be set may be set.

  With such a configuration, it is possible to prevent the gradation expression of the dark part in the entire image displayed on the display screen from being impaired and to further improve the image quality.

  In order to achieve the above object, according to the second aspect of the present invention, the display screen is divided into a plurality of divided areas, and the average luminance for each of the divided areas is calculated based on the input video signal. Determining a divided region where a local common electrode voltage drop may occur on the display screen based on the step and the average luminance for each divided region, and determining the gain of the video signal corresponding to the determined divided region A step of setting a correction center position for setting to a predetermined value or less at which occurrence of a voltage drop is prevented; a step of setting a correction value according to the display position of the display screen with the correction center position as a base point; Adjusting the gain of the video signal based on the correction value.

  By using such a method, it is possible to control luminance based on an input video signal, to prevent display failure due to a voltage drop caused by the resistance of the common electrode, and to reduce power consumption.

  In order to achieve the above object, according to the third aspect of the present invention, the display screen is divided into a plurality of divided areas, and the average luminance for each of the divided areas is calculated based on the input video signal. Determining a divided region where a local common electrode voltage drop may occur on the display screen based on the average luminance for each divided region, and determining the gain of the video signal corresponding to the determined divided region as the voltage A step of setting a correction center position for setting below a predetermined value to prevent the occurrence of a descent, a step of setting a correction value according to the display position of the display screen with the correction center position as a base point, the correction value A program for causing the computer to execute the step of adjusting the gain of the video signal based on the above is provided.

  With such a program, it is possible to control the luminance based on the input video signal, to prevent display failure due to a voltage drop caused by the resistance of the common electrode, and to reduce power consumption.

  In order to achieve the above object, according to a fourth aspect of the present invention, a video signal correcting unit that corrects an input video signal and a video based on the video signal corrected by the video signal correcting unit are provided. An image display unit for displaying on a display screen, wherein the video signal correction unit divides the display screen into a plurality of divided regions and calculates an average luminance for each of the divided regions based on the input video signal. Based on the luminance calculation unit and the average luminance for each of the divided areas, a divided area where a local common electrode voltage drop may occur in the display screen is determined, and the gain of the video signal corresponding to the determined divided area A correction center setting unit for setting a correction center position for setting the voltage drop below a predetermined value that prevents the occurrence of the voltage drop, and a correction value corresponding to the display position of the display screen with the correction center position as a base point Setting A correction value setting unit for a display device and a gain adjustment unit which adjusts the gain of the video signal based on the correction value is provided.

  With such a configuration, it is possible to control luminance based on an input video signal, to prevent display failure due to a voltage drop caused by the resistance of the common electrode, and to reduce power consumption.

  According to the present invention, by controlling the luminance based on the input video signal, it is possible to prevent display failure due to a voltage drop caused by the resistance of the common electrode and reduce power consumption.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Approach in a video signal processing apparatus according to an embodiment of the present invention)
Before describing the configuration of a video signal processing apparatus according to an embodiment of the present invention (hereinafter sometimes referred to as “video signal processing apparatus 100”), first, due to the resistance of the common electrode in the video signal processing apparatus 100 An approach for preventing display failure due to a voltage drop and reducing power consumption will be described. Note that the following approach applies not only to the video signal processing apparatus according to the embodiment of the present invention but also to the display apparatus according to the embodiment of the present invention.

  FIG. 1 is an explanatory diagram for explaining an approach for preventing a display defect due to a voltage drop caused by a common electrode resistance and reducing power consumption in the video signal processing apparatus 100 according to the embodiment of the present invention. Here, FIG. 1A shows a display screen that displays an image corresponding to a video signal, and shows an example in which an image similar to FIG. 17A is displayed. That is, the area A in FIG. 1A shows an area where a voltage drop due to the resistance Ro of the common electrode is likely to occur. FIG. 1B shows the relationship between the display position (Position) of the display screen shown in FIG. 1A and the target gain (Gain) after correction of the video signal. Here, in FIG. 1, the target gain (Gain) at each display position corresponds to a correction value set by a correction value setting unit 106 described later. In FIG. 1B, the horizontal direction is shown as an example of the display position (Position). Similarly, in the vertical direction, the gain is attenuated toward the end of the display screen using the correction center position as a base point. Can do. In FIG. 1B, the gain shown in FIG. 17B is shown for comparison with a device using a conventional technique that lowers the luminance toward the screen edge from the physical center point of the display screen. Is shown as an example of adjustment (broken line in FIG. 1B).

  As shown in FIG. 1B, it can be seen that the video signal processing apparatus 100 attenuates the gain toward the periphery with the correction center position corresponding to the position C1 as a base point. Here, the correction center position in the video signal processing apparatus 100 shown in FIG. 1B is the physical center point of the display screen (corresponding to the Center in FIG. 1B) as in the apparatus using the conventional technique. is not. As shown in FIG. 1B, the video signal processing device 100 attenuates the gain toward the periphery with the correction center position corresponding to the position C1 as a base point, so that the video signal processing apparatus 100 inputs the video input at the position P1 corresponding to the area A. The signal gain can be lowered by q1. Here, as is apparent from FIG. 1B, q1 shown in FIG. 1B has a relationship of q1> q10. Therefore, in the example shown in FIG. 1B, the video signal processing apparatus 100 is more reliably defective due to a voltage drop caused by the resistance Ro of the common electrode than the apparatus using the conventional technique shown in FIG. Can be prevented.

  Further, when looking at a user who views an image based on the video signal processed by the video signal processing apparatus 100, the user generally has a characteristic that attention is concentrated at the center of the display screen (human visual characteristic). . Conversely, the user is generally distracted as he goes to the periphery of the display screen. Furthermore, a producer (for example, various production companies) that produces a video (image) source indicated by a video signal processed by the video signal processing apparatus 100 often displays important information in consideration of the characteristics of the user. Produce an image placed in the center of the screen. Therefore, as shown in FIG. 1B, even if the video signal processing apparatus 100 attenuates the gain toward the periphery with the correction center position as a base point, the image quality does not deteriorate.

  As described above, the video signal processing apparatus 100 prevents display defects due to a voltage drop caused by the resistance Ro of the common electrode by attenuating the gain toward the periphery with a certain correction center position as a base point. Here, in the video signal processing apparatus 100, the correction center position is set based on the input video signal. A method for setting the correction center position in the video signal processing apparatus 100 will be described later.

  In addition, when the video signal processing apparatus 100 is applied to a display device, the display device increases the power supply voltage supplied to each pixel circuit constituting the display panel so as to have a margin for operation of the pixel circuit. There is no need. Further, since the video signal processing apparatus 100 attenuates the gain of the video signal toward the periphery with a certain correction center position as a base point, when the video signal processing apparatus 100 is applied to the display device, it is consumed by the display panel. It is possible to further reduce power consumption. Furthermore, even if the gain of the video signal is attenuated toward the periphery with the correction center position as the base point as described above, the image quality does not deteriorate, so that the display device to which the video signal processing apparatus 100 is applied has a high image quality. Simple images can be displayed.

  Therefore, the video signal processing apparatus 100 attenuates the gain toward the periphery (controls the luminance) based on a certain correction center position based on the input video signal, thereby causing a voltage due to the resistance Ro of the common electrode. It is possible to prevent a display defect due to a drop and reduce power consumption.

(Outline of processing in the video signal processing apparatus according to the embodiment of the present invention)
Next, an outline of processing in the video signal processing apparatus according to the embodiment of the present invention will be described. As shown in FIG. 1B, the video signal processing apparatus 100 according to the embodiment of the present invention has a base point (hereinafter referred to as “correction center position”) for correcting the video signal based on the input video signal. It is set appropriately, and the gain of the video signal is continuously attenuated toward the end of the display screen with the set correction center position as the center. Here, the “continuous” according to the embodiment of the present invention may include a pseudo continuation by collecting discrete values.

  More specifically, the video signal processing apparatus 100 can process video signals as shown in (I) to (III) below, for example. In the following, an outline of processing in the video signal processing apparatus 100 will be described with reference to FIGS. 2 to 4 as appropriate. Here, each of FIGS. 2 to 4 is an explanatory diagram for explaining an outline of processing in the video signal processing apparatus 100 according to the embodiment of the present invention.

(I) Correction center position selection process 1
As shown in FIG. 2, the video signal processing apparatus 100 divides a display screen that displays an image indicated by an input video signal into a plurality of divided areas, and the video signal for each of the divided areas based on the input video signal. The average luminance of is derived.

  Here, FIG. 2 shows an example in which the area is divided into 24 areas A1 to A24, but it goes without saying that the number of divided areas according to the embodiment of the present invention is not limited to 24 areas. Further, the number of divided areas according to the embodiment of the present invention may be a predetermined number, for example, or may be a user input from a user who uses the video signal processing apparatus 100 or an input video signal. It may be set as appropriate according to the resolution or the like.

(II) Correction center position selection process 2
The video signal processing apparatus 100 determines a divided region having the highest average luminance based on the average luminance calculated for each divided region. Then, when the correction center position is set and the gain is adjusted, the video signal processing apparatus 100 makes the signal level of the video signal corresponding to the determined divided area smaller than a predetermined value (or The center position of the divided area that can be set to a predetermined value or less is set as the correction center position of the video signal. Here, the video signal processing apparatus 100, for example, looks up a look-up table (Look Up) in which a divided area (corresponding to a divided area determined to have a high average luminance) and a correction center position corresponding to the divided area are associated with each other. Table) can be used to uniquely set the correction center position corresponding to the divided area having the highest average luminance, but is not limited to the above. The correction center position recorded in the look-up table is set in the divided area after setting various conditions such as the size of the display panel, the type of common electrode used in the display panel, and the number of divided areas. It can be derived in advance by using the case where the average luminance is maximum. Furthermore, in the lookup table, for example, the center position of the divided area closest to the central portion of the display screen among the divided areas satisfying the conditions selected as the corrected center position can be recorded as the corrected center position. It is not limited to the above.

(III) Video Signal Correction Processing As shown in FIGS. 3 and 4, the gain of the video signal is continuously attenuated toward the end of the display screen around the set correction center position, and the luminance is adjusted. Here, FIG. 3 shows an example in which the divided area A8 is set as the correction center position, and FIG. 4 shows an example in which the divided area A16 is set as the correction center position.

  The video signal processing apparatus 100 according to the embodiment of the present invention controls the luminance by performing the processes shown in the above (I) to (III). Here, the video signal processing apparatus 100 sets the correction center position based on the input video signal, and there is a high possibility that a voltage drop due to the divided area having a high average luminance (that is, the resistance Ro of the common electrode) occurs. The signal level of the video signal corresponding to the division area is adjusted to a signal level that prevents the occurrence of a voltage drop due to the resistance Ro of the common electrode. Therefore, the video signal processing apparatus 100 can prevent a display defect due to a voltage drop caused by the resistance Ro of the common electrode.

  Further, as shown in FIG. 1B, the video signal processing apparatus 100 attenuates the gain toward the periphery with the set correction center position as a base point, thereby causing a voltage drop caused by the resistance Ro of the common electrode. Prevent display defects. That is, a display panel that displays video based on the video signal processed by the video signal processing device 100 (or a display device to which the video signal processing device 100 is applied. Hereinafter, it may be referred to as a “display device 200”). Thus, it is not necessary to set the power supply voltage supplied to each pixel circuit high. Further, since the video signal processing apparatus 100 attenuates the gain toward the periphery with the correction center position as a base point as shown in FIG. 1B, the display device 200 uses a display panel corresponding to the attenuated gain. The consumed power is reduced.

  Therefore, the video signal processing apparatus 100 can prevent display failure and reduce power consumption due to a voltage drop caused by the resistance Ro of the common electrode by controlling the luminance based on the input video signal. .

  In addition, the display device 200 according to the embodiment of the present invention includes the video signal processing device 100, and displays an image and a video corresponding to the video signal whose luminance is controlled in the same manner as the video signal processing device 100. Therefore, the display device 200 can prevent display failure due to a voltage drop caused by the resistance Ro of the common electrode and reduce power consumption by controlling the luminance based on the input video signal.

  Hereinafter, the configurations of the video signal processing apparatus 100 and the display apparatus 200 according to the embodiment of the present invention will be described in more detail. In the following description, the video signal is input to the video signal processing apparatus 100 or the display apparatus 200. However, the video signal input to the video signal processing apparatus 100 or the display apparatus 200 indicates a still image. It may be a moving image (so-called video). Hereinafter, the still image or moving image (video) displayed on the display screen may be simply referred to as “image”.

(Video signal processing apparatus according to an embodiment of the present invention)
FIG. 5 is a block diagram showing an example of the video signal processing apparatus 100 according to the embodiment of the present invention. Here, although one video signal is shown in FIG. 5, the embodiment of the present invention is not limited to such a configuration. For example, the input video signal is red, green, and blue. An independent signal may be used for each color.

  In the following description, it is assumed that the video signal input to the video signal processing apparatus 100 is a digital signal used in, for example, digital broadcasting, but is not limited thereto. For example, the video signal input to the video signal processing apparatus 100 can be an analog signal used in analog broadcasting or the like. Note that the video signal input to the video signal processing apparatus 100 according to the embodiment of the present invention can be transmitted from a broadcasting station and received by the video signal processing apparatus 100, for example, but is not limited thereto. . For example, the video signal input to the video signal processing device 100 according to the embodiment of the present invention is transmitted from an external device via a network such as a LAN (Local Area Network) and received by the video signal processing device 100. Alternatively, the video signal processing device 100 may read a video file or an image file held in a storage unit (not shown) included in the video signal processing device 100.

  Referring to FIG. 5, the video signal processing apparatus 100 includes an average luminance calculation unit 102, a correction center setting unit 104, a correction value setting unit 106, and a gain adjustment unit 108. Signal processing in the average luminance calculation unit 102, the correction center setting unit 104, the correction value setting unit 106, and the gain adjustment unit 108 described below is performed by, for example, hardware (for example, a signal processing circuit) and / or software (signal). Processing software).

  In addition, the video signal processing device 100 includes, for example, a control unit (not shown) configured by an MPU (Micro Processing Unit) or the like that can control the entire video signal processing device 100, a program used by the control unit, A ROM (Read Only Memory) (not shown) in which control data such as calculation parameters are recorded, a RAM (Random Access Memory) (not shown) that primarily stores programs executed by the control unit, and an average luminance calculation unit 102 A storage unit (not shown) capable of storing data used for calculating average luminance in the correction value and setting correction values in the correction value setting unit 106, and a receiving unit (not shown) for receiving a video signal transmitted from a broadcasting station or the like. Or an operation unit (not shown) that can be operated by the user. The video signal processing apparatus 100 can connect the above-described constituent elements by, for example, a bus as a data transmission path.

  Here, as a storage unit (not shown), for example, a magnetic recording medium such as a hard disk, a nonvolatile memory such as a flash memory, a magneto-optical disk (Magneto Optical Disk) ) Etc., but is not limited to the above. In addition, examples of the operation unit (not shown) include operation input devices such as a keyboard and a mouse, buttons, direction keys, and combinations thereof, but are not limited thereto. Absent.

  The average luminance calculation unit 102 calculates an average value of luminance in a predetermined period based on the input video signal. The predetermined period in which the average luminance calculation unit 102 calculates the average luminance is, for example, one frame period, but is not limited to the above. For example, the predetermined period is adjusted to a period for adjusting the gain of the video signal in the gain adjustment unit 108 described later. It can also be a period. Hereinafter, the predetermined period in which the average luminance calculation unit 102 calculates the average luminance will be described as one frame period.

  Further, as shown in FIG. 2, the average luminance calculation unit 102 divides a display screen that displays an image indicated by the input video signal into a plurality of divided areas, and for each divided area based on the input video signal. The average luminance of the video signal is calculated. Information such as the number and size of the divided areas used by the average luminance calculation unit 102 to calculate the average luminance can be stored in the storage unit, for example, provided in the average luminance calculation unit 102. Here, as the storage means included in the average luminance calculation unit 102, for example, EEPROM (Electrically Erasable and Programmable Read Only Memory), flash memory, MRAM (Magnetoresistive Random Access Memory), FeRAM (Ferroelectric Random Access Memory), PRAM (Phase non-volatile memory such as change Random Access Memory), but is not limited to the above. Information such as the number and size of the divided areas used by the average luminance calculation unit 102 to calculate the average luminance is stored in, for example, a storage unit (not shown) of the video signal processing device 100, and the average luminance calculation unit It goes without saying that 102 may appropriately read from the storage unit (not shown).

  As a method for calculating the average luminance in the predetermined period calculated by the average luminance calculation unit 102, for example, an arithmetic average is used. However, the average luminance is not limited to the above. For example, the average luminance is calculated using a geometric average or a weighted average. You can also.

  The correction center setting unit 104 sets the correction center position based on the average luminance calculated for each divided region by the average luminance calculation unit 102. More specifically, the correction center setting unit 104 sets the correction center position by, for example, the following processes (i) and (ii).

(I) Determination (selection) of a divided region having the highest average luminance
For example, the correction center setting unit 104 temporarily selects one divided region as a determination candidate region, compares the average luminance of the one divided region with the average luminance of the other divided regions, and selects a divided region having a high average luminance. A new determination candidate area is set. By repeating the above comparison, the correction center setting unit 104 can specify a divided region having the highest average luminance. In addition, when the average luminance of one divided region is equal to the average luminance of the other divided regions, for example, one of the divided regions is determined as a determination candidate region based on a priority predetermined for each divided region. To do. For example, the priority is set higher in a divided area closer to the center of the display screen, but is not limited thereto. Here, various information such as the divided areas to be compared by the correction center setting unit 104 and the average luminance value of each of the divided areas may be stored in the correction unit, for example, provided in the correction center setting unit 104. . Examples of the storage means included in the correction center setting unit 104 include volatile memory such as SDRAM (Synchronous Dynamic Random Access Memory) and SRAM (Static Random Access Memory), but are not limited thereto. It may be a non-volatile memory such as a flash memory. Needless to say, the method of comparing the average luminance in the correction center setting unit 104 is not limited to the above.

(Ii) Setting Correction Center Position The correction center setting unit 104 sets the correction center position based on the divided area determined in the process (i). Here, the correction center setting unit 104 uses, for example, the division determined in the process (i) by using a look-up table in which a divided area and a correction center position corresponding to the divided area are associated with each other. The correction center position can be set uniquely based on the region. For example, although the correction center setting unit 104 includes a storage unit and can be held in the storage unit, the lookup table is not limited to the above. For example, the correction center setting unit 104 can appropriately read the lookup table stored in the storage unit (not shown) of the video signal processing apparatus 100.

  The correction center setting unit 104 can set the correction center position based on the input video signal, for example, by the process (i) and the process (ii).

  The correction value setting unit 106 sets a correction value for correcting the video signal based on the correction center position set by the correction center setting unit 104 according to the display position of the display screen that displays an image corresponding to the video signal. Set. Hereinafter, a correction value setting method in the correction value setting unit 106 will be described. In the following, a case where the center point of the divided area A8 shown in FIG. 2 is set as the correction center position will be mainly described as an example.

[First correction value setting method]
FIG. 6 is an explanatory diagram for explaining a first correction value setting method in the correction value setting unit 106 according to the embodiment of the present invention. Here, FIG. 6A shows a display screen for displaying an image corresponding to the video signal, and FIG. 6B shows a display position (Position) of the display screen shown in FIG. 6A. And the target gain (Gain) after correction of the video signal. In FIG. 6, the target gain (Gain) at each display position corresponds to the correction value set by the correction value setting unit 106.

  As shown in FIG. 6A, the correction value setting unit 106 using the first correction value setting method uses the correction center position C1 set as the center point of the divided area A8 as a base point to the end of the display screen. A correction value that attenuates the gain is set. In FIG. 6B, the horizontal direction is shown as an example of the display position (Position). Similarly, in the vertical direction, the gain is attenuated toward the end of the display screen using the correction center position as a base point. Can do.

  Further, as shown in FIG. 6B, the correction value setting unit 106 uses, for example, the distance (d1, d2) from the correction center position C1 to the display screen edge and the gain reduction width g1. A correction value corresponding to the display position (Position) is set.

  Here, the gain reduction width g1 can be defined by a preset upper limit value and lower limit value of the gain. For example, in FIG. 6B, “1.0” is set as the upper limit value, and the gain of the video signal does not change at the correction center position C1 at which the upper limit value is set. FIG. 6B shows an example in which “0.8” is set as the lower limit value. Needless to say, the upper and lower limits according to the embodiment of the present invention are not limited to the above. The upper limit value and the lower limit value of the gain can be fixed values, but are not limited thereto. For example, the video signal processing apparatus 100 can prevent a display defect due to a voltage drop caused by the common electrode resistance Ro in response to a user input from an operation unit (not shown) of the video signal processing apparatus 100. The upper limit value and the lower limit value of the gain may be appropriately changed.

  Information such as the upper limit value and the lower limit value used by the correction value setting unit 106 to set the correction value can be stored in the storage unit, for example, provided in the correction value setting unit 106. Here, examples of the storage unit included in the correction value setting unit 106 include a nonvolatile memory such as an EEPROM or a flash memory, but are not limited thereto. Information such as an upper limit value and a lower limit value used by the correction value setting unit 106 to set the correction value is stored in, for example, a storage unit (not shown) of the video signal processing apparatus 100, and the correction value setting unit 106 Needless to say, may be appropriately read from the storage unit (not shown).

  By using the first correction value setting method as described above, the correction value setting unit 106 sets a correction value that attenuates the gain of the video signal toward the screen edge of the display screen with the correction center position as a base point. can do.

[Second correction value setting method]
The first correction value setting method shown in FIG. 6 shows a method of setting a correction value for attenuating the gain of the video signal corresponding to the display screen edge to the lower limit value of the gain regardless of the correction center position. However, the correction value setting method according to the embodiment of the present invention is not limited to the first correction value setting method shown in FIG. Then, next, a method for changing the lower limit value of the gain according to the correction center position will be described as a second correction value setting method.

  FIG. 7 is an explanatory diagram for explaining a second correction value setting method in the correction value setting unit 106 according to the embodiment of the present invention. Here, FIG. 7A shows a display screen for displaying an image corresponding to the video signal, as in FIG. FIG. 7B shows the relationship between the display position (Position) of the display screen shown in FIG. 7A and the target gain (Gain) after correction of the video signal, as in FIG. 6B. ing.

  As shown in FIG. 7A, the correction value setting unit 106 that uses the second correction value setting method is the correction center position set at the center point of the divided area A8, as in the first correction value setting method. A correction value that attenuates the gain toward the end of the display screen is set with C1 as a base point.

  Here, when FIG. 7B is compared with FIG. 6B relating to the first correction value setting method, the second correction value setting method has a lower limit of the gain of the video signal corresponding to the display screen edge Left. It can be seen that the value L differs from the lower limit value 0.8 of the gain of the video signal corresponding to the display screen end Right. If the lower limit value of the gain of the video signal is the same between the display screen edge Left and the display screen edge Right, the luminance of one display screen edge may be extremely lowered depending on the position of the correction center position. This is because there is (that is, the gain attenuation rate increases).

  The correction value setting unit 106 using the second correction value setting method has a predetermined reference position of the correction center position in order to prevent the luminance of one display screen end from being extremely lowered as described above. The lower limit value of the gain of the video signal is appropriately set according to the “deviation amount” with respect to. By appropriately setting the lower limit value of the gain of the video signal as described above, the correction value setting unit 106 can change the attenuation rate of the gain of the video signal.

  Here, the “deviation amount” is determined using, for example, the center position of the display screen (Center in FIG. 7B) as the reference position. For example, in FIG. 7B, the shift amount is represented by “z”. Note that the shift amount according to the embodiment of the present invention is a value corresponding to a distance corresponding to one direction of the display screen (for example, the horizontal direction of the display screen) as the shift amount z in FIG. However, it is not limited to the above, and may be, for example, a Euclidean distance between a reference position (for example, a mechanical center) and a correction center position.

  For example, the correction value setting unit 106 may set the lower limit value L of the gain according to the determined deviation amount z using a lookup table in which the deviation amount z and the lower limit value L of the gain are associated with each other. it can. The lookup table used by the correction value setting unit 106 to set the correction value can be stored in, for example, a storage unit included in the correction value setting unit 106, but is not limited thereto, and is stored in the video signal processing device 100. It may be appropriately read from a unit (not shown). The means for setting the lower limit L of the gain according to the embodiment of the present invention is not limited to the above, and for example, the lower limit of the gain is obtained by adding a value corresponding to the shift amount to the preset lower limit of the gain. L can also be set.

  As described above, the correction value setting unit 106 using the second correction value setting method is different from the case of using the first correction value setting method in that the lower limit value L of the gain is set according to the shift amount z. However, the basic correction value setting method is the same as the first correction value setting method. That is, the correction value setting unit 106 using the second correction value setting method, as in the case of using the first correction value setting method, the distance (d1, d2) from the correction center position C1 to the display screen edge, A correction value corresponding to the display position (Position) of the display screen is set using the gain reduction width g1 and the gain reduction width g2 defined by the lower limit value L of the gain.

  Therefore, by using the second correction value setting method as described above, the correction value setting unit 106 sets a correction value that attenuates the gain of the video signal from the correction center position toward the screen edge of the display screen. Can be set.

[Third correction value setting method]
In the above, as the first correction value setting method and the second correction value setting method, the correction value setting for setting the correction value for attenuating the gain of the video signal from the correction center position toward the screen edge of the display screen. The method was explained. Here, in the case of controlling the luminance, when the video signal gain adjustment (amplitude control) is performed by simply multiplying the input video signal by a coefficient, for example, an image displayed on the display screen The gradation expression of the dark part in the whole may be impaired. Therefore, next, as a third correction value setting method according to the embodiment of the present invention, a correction value setting method capable of preventing the above-described dark portion gradation expression from being impaired will be described. Note that the third correction value setting method described below is performed in combination with, for example, the first correction value setting method or the second correction value setting method described above. Hereinafter, the description of the third correction value setting method corresponding to the first correction value setting method or the second correction value setting method will be omitted.

  FIG. 8 is an explanatory diagram for explaining a third correction value setting method in the correction value setting unit 106 according to the embodiment of the present invention. The correction value setting unit 106 using the third correction value setting method indicates, for example, when the luminance indicated by the input video signal is greater than a predetermined threshold TH, as shown in FIG. The correction value is set so that the luminance reduction rate increases as the luminance increases. Here, the correction value setting unit 106 uses a lookup table in which the luminance value of the video signal and the correction value are associated with each other, for example, a correction value (in accordance with the average luminance calculated by the average luminance calculating unit 102 ( The correction value for realizing FIG. 8 can be set, but is not limited to the above.

  The correction value setting unit 106 provides a correction characteristic in which the relationship between the input video signal and the video signal after gain adjustment (after correction) as shown in FIG. The gradation expression in the dark portion can be maintained while preventing display defects due to voltage drop caused by the resistance Ro of the common electrode.

[Fourth correction value setting method]
The correction value setting unit 106 can set a correction value corresponding to the correction center position for each frame period (predetermined period) by using the first to third correction value setting methods described above. Therefore, the video signal processing apparatus 100 uses the first to third correction value setting methods described above to prevent display failure due to a voltage drop caused by the resistance Ro of the common electrode and to reduce power consumption. Can do. As described above, the correction value setting unit 106 can set a correction value suitable for correcting the video signal for each frame by using the first to third correction value setting methods described above. However, even if an appropriate correction value is set for each frame, an unexpected problem may occur in terms of image quality when viewed in a plurality of frames.

[Problems covered by the fourth correction value setting method]
FIG. 9 is an explanatory diagram for explaining a problem targeted by the fourth correction value setting method in the correction value setting unit 106 according to the embodiment of the present invention. FIGS. 9A and 9B show the correction center position and the correction value in a certain frame, and the correction center setting unit 104 determines that the divided areas A17 and A14 are the divided areas having the highest average luminance. An example is shown. 9C shows the correction center position and the correction value in the next frame of the frame shown in FIG. 9A, and FIG. 9D shows the next frame of the frame shown in FIG. 9B. The correction center position and the correction value are shown.

  For example, as shown in FIG. 9, the correction center position is changed from the correction center position C1 of the divided region A8 (FIG. 9A: first correction center position) to the correction center position C2 of the divided region A11 (FIG. 9C): When the position changes to (second correction center position), the correction value corresponding to the display position on the display screen is also set to a value corresponding to each correction center position (FIGS. 9B and 9D). ). However, when the correction center position changes as described above, as is apparent from a comparison between FIG. 9B and FIG. The correction value corresponding to the display position may change abruptly.

  As shown in FIG. 9, when the correction value corresponding to the display position of the display screen changes abruptly by transition of one frame, there is a possibility that the change in luminance appears on the display screen. Therefore, in the above case, even if the video signal suitable for each frame is corrected, there is a possibility that the image quality of the image displayed on the display screen is deteriorated.

  Therefore, a fourth correction value setting method capable of suppressing the occurrence of the above problem as shown in FIG. 9 will be described next.

[Problem solving approach of the fourth correction value setting method]
FIG. 10 is an explanatory diagram for explaining a fourth correction value setting method in the correction value setting unit 106 according to the embodiment of the present invention.

  The correction value setting unit 106 using the fourth correction value setting method changes the correction value stepwise in order to suppress the occurrence of the above problem as shown in FIG. For example, FIG. 10 is a step in four frame periods from the correction center position C1 (first correction center position) shown in FIG. 9A to the correction center position C2 (second correction center position) shown in FIG. 9C. This is an example of changing the pattern.

  When the correction center position changes from the correction center position C1 to the correction center position C2, the correction value setting unit 106 using the fourth correction value setting method, for example, has an intermediate correction center obtained by dividing the distance between C1 and C2 into four equal parts. The position ("C1-1" to "C1-3" in FIG. 10) is determined. The correction value setting unit 106 sets a correction value based on the intermediate correction center position C1-1 for the first frame (FIG. 10B), and uses the intermediate correction center position C1-2 for the second frame. A correction value is set (FIG. 10C). Similarly, the correction value setting unit 106 sets a correction value with the intermediate correction center position C1-3 as the base point in the third frame (FIG. 10D), and the target correction center position in the fourth frame. A correction value with a certain correction center position C2 as a base point is set (FIG. 10E).

  Therefore, the correction value setting unit 106 using the fourth correction value setting method can prevent the correction value from changing suddenly at the transition of one frame as shown in FIG. 9, and as shown in FIG. The occurrence of the above problems can be suppressed.

  Further, FIG. 10 shows an example in which the correction value is set by changing the correction center position step by step from the correction center position C1 to the correction center position C2 in four frame periods. The correction center position to be changed may change (that is, the correction center setting unit 104 sets a new correction center position). In the above case, the correction value setting unit 106 determines a new intermediate correction center position from, for example, the correction center position in the current frame and the new correction center position set by the correction center setting unit 104, thereby correcting the correction value. Can be set.

  Information such as the correction center position in the current frame used for setting the correction value by the correction value setting unit 106, the target correction center position (the correction center position set by the correction center setting unit 104), the intermediate correction center position, and the like For example, the correction value setting unit 106 includes a storage unit and can be held in the storage unit, but is not limited thereto. Here, examples of the storage unit included in the correction value setting unit 106 include a volatile memory such as SDRAM and SRAM, but are not limited to the above, and may be a non-volatile memory such as a flash memory.

[Fifth correction value setting method]
The correction value setting unit 106 appropriately moves the first to third correction value setting methods described above and the fourth correction value setting method to use the correction center position as a base point and move toward the screen edge of the display screen. Thus, a correction value for attenuating the gain of the video signal can be set.

  For example, by using the above-described first to fifth correction value setting methods, the correction value setting unit 106 uses the correction center position as a base point to correct the gain of the video signal toward the screen edge of the display screen. Can be set. Therefore, the correction value setting unit 106 can set a correction value according to the display position of the display screen. Needless to say, the correction value setting method used by the correction value setting unit 106 according to the embodiment of the present invention is not limited to the first to fifth correction value setting methods described above.

  The configuration of the video signal processing apparatus 100 will be described with reference to FIG. 5 again. The gain adjustment unit 108 adjusts the gain of the input video signal using the correction value set by the correction value setting unit 106. More specifically, the gain adjustment unit 108 attenuates the gain of the video signal, for example, by multiplying the video signal by a correction value corresponding to the display position of the display screen set by the correction value setting unit 106. . Here, the gain adjustment unit 108 can be configured by, for example, a multiplier, but is not limited thereto.

  In addition, the gain adjustment unit 108 stores, for example, a lookup table in which the display position of the display screen is associated with the correction value, and reads a correction value corresponding to the display position of the display screen from the lookup table. it can. For example, the gain adjustment unit 108 updates the value of the correction value in the lookup table every time the correction value is transmitted from the correction value setting unit 106. Here, for example, the look-up table used by the gain adjusting unit 108 to adjust the gain of the video signal can be held in the storing unit. Examples of the storage means included in the gain adjustment unit 108 include a nonvolatile memory such as an EEPROM or a flash memory, but are not limited thereto. Note that the look-up table used by the gain adjusting unit 108 to adjust the gain of the video signal is stored in, for example, a storage unit (not shown) of the video signal processing device 100, and the gain adjusting unit 108 sets the correction value. Needless to say, the information may be appropriately updated and may be appropriately read from the storage unit (not shown).

  The gain adjusting unit 108 can output the video signal whose gain has been adjusted to, for example, a display device including a display screen that displays an image. The output destination from which the gain adjusting unit 108 outputs the video signal whose gain has been adjusted is not limited to the above. For example, the gain adjustment unit 108 can store a video signal whose gain has been adjusted in a storage unit (not shown) included in the video signal processing apparatus 100, or a PC (Personal) via a wired / wireless network or the like. To an external computer such as Computer).

  As described above, the video signal processing apparatus 100 according to the embodiment of the present invention calculates the average luminance for each divided region based on the input video signal, and corrects based on the calculated average luminance for each divided region. Set the center position. Here, the video signal processing apparatus 100, for example, a division that can make the signal level of the video signal corresponding to the divided area with the highest average luminance smaller than a predetermined value (or less than a predetermined value). The center position of the area is set as the correction center position of the video signal. In addition, the video signal processing apparatus 100 sets a correction value for attenuating the gain of the video signal toward the screen edge of the display screen using the set correction center position as a base point. Then, the video signal processing apparatus 100 adjusts (attenuates) the gain of the video signal by multiplying the input video signal by a correction value corresponding to the set display position of the display screen. By adjusting the gain of the video signal as described above, the video signal processing apparatus 100 is highly likely to cause a display defect due to a voltage drop caused by the resistance Ro of the common electrode, which is the highest average luminance. The signal level of the (divided area) can be made smaller than a predetermined value (or less than a predetermined value). Therefore, the video signal processing apparatus 100 can prevent display failure due to a voltage drop caused by the resistance Ro of the common electrode by controlling the luminance of the video signal.

  In addition, when the video signal processing apparatus 100 is applied to a display device, the display device increases the power supply voltage supplied to each pixel circuit constituting the display panel so as to have a margin for operation of the pixel circuit. There is no need. Furthermore, since the video signal processing device 100 attenuates the gain toward the periphery with a certain correction center position as a base point, when the video signal processing device 100 is applied to a display device, power consumption consumed by the display panel Can be further reduced.

  Therefore, the video signal processing apparatus 100 attenuates the gain toward the periphery (controls the luminance) based on a certain correction center position based on the input video signal, thereby causing a voltage due to the resistance Ro of the common electrode. It is possible to prevent a display defect due to a drop and reduce power consumption.

  Further, the video signal processing apparatus 100 can appropriately change the attenuation factor of the gain of the video signal in accordance with the amount of deviation of the set correction center position with respect to a predetermined reference position. Therefore, the video signal processing apparatus 100 can control the luminance of the video signal so as to achieve higher image quality.

  In addition, the video signal processing apparatus 100 corrects the input video signal in accordance with correction characteristics in which the relationship between the input video signal and the corrected video signal is not constant, as shown in FIG. 8, for example. Can be set. Therefore, the video signal processing apparatus 100 can maintain the gradation expression in the dark part (to achieve higher image quality) while preventing display failure due to the voltage drop caused by the resistance Ro of the common electrode.

  Further, the video signal processing apparatus 100 can change the correction value stepwise in order to prevent the image quality from being deteriorated due to a sudden change in luminance when displayed on the display screen. Therefore, the video signal processing apparatus 100 can control the luminance of the video signal so as to achieve higher image quality.

  In the above description, the video signal processing apparatus 100 has been described as an embodiment of the present invention, but the embodiment of the present invention is not limited to such a form. For example, embodiments of the present invention include a self-luminous display device such as an organic EL display, FED, and PDP, a display device having a separate light source such as an LCD, a computer such as a PC and a server, a mobile phone, and the like. The present invention can be applied to various devices such as portable communication devices. The application to the display device will be described later.

(Program related to video signal processing apparatus 100)
In accordance with the program for causing the computer to function as the video signal processing apparatus 100 according to the embodiment of the present invention, the luminance is controlled based on the input video signal, and the display failure due to the voltage drop caused by the resistance of the common electrode is prevented. And power consumption can be reduced.

(Video signal processing method according to an embodiment of the present invention)
Next, a video signal processing method according to an embodiment of the present invention will be described. FIG. 11 is a flowchart showing an example of a video signal processing method according to the embodiment of the present invention. In the following, the case where the video signal processing apparatus 100 performs the video signal processing method according to the embodiment of the present invention will be described as an example, but the video signal processing method according to the embodiment of the present invention will be described later. The present invention can also be applied to the display device 200 according to the embodiment of the invention.

  When the video signal is input, the video signal processing apparatus 100 calculates an average luminance for each divided region (S100). Here, the average luminance for each divided region in step S100 can be, for example, the average luminance in one frame period, but is not limited thereto. The average luminance in step S100 can be calculated using, for example, an arithmetic average, but is not limited to the above, and can be calculated using, for example, a geometric average or a weighted average.

  The video signal processing apparatus 100 sets the correction center position based on the average luminance for each divided area calculated in step S100 (S102). Here, the video signal processing apparatus 100 uses, for example, a lookup table in which a divided area and a correction center position corresponding to the divided area are associated, thereby correcting the correction center corresponding to the divided area having the highest average luminance. The position can be set uniquely.

  The video signal processing apparatus 100 sets a correction value according to the display position of the display screen when displaying the image indicated by the video signal on the display screen based on the correction center position set in step S102 (S104). Here, the setting of the correction value in step S104 can be performed using, for example, the first to fifth correction value setting methods described above.

  Based on the correction value set in step S104, the video signal processing apparatus 100 adjusts the gain of the input video signal (S106). Here, in step S104, a correction value that attenuates the gain toward the edge of the display screen is set with the correction center position as a base point. Therefore, the video signal adjusted in step S106 is the edge of the display screen. The gain corresponding to the video signal corresponding to the part is attenuated.

  As described above, in the video signal processing method according to the embodiment of the present invention, the average luminance for each divided region is calculated based on the input video signal, and the correction center position is calculated based on the calculated average luminance for each divided region. Set. Then, a correction value corresponding to the display position on the display screen is set using the set correction center position as a base point, and the gain of the video signal input is adjusted based on the set correction value. Here, in the video signal processing method according to the embodiment of the present invention, a signal in a divided region having the highest average luminance (that is, a divided region in which a display defect due to a voltage drop caused by the resistance Ro of the common electrode is highly likely to occur). The gain of the video signal is adjusted so that the level is smaller than a predetermined value (or less than the predetermined value). Further, in the video signal processing method according to the embodiment of the present invention, the luminance is controlled by attenuating the gain toward the edge of the display screen with the correction center position as a base point. Can be reduced.

  Therefore, by using the video signal processing method according to the embodiment of the present invention, the video signal processing apparatus 100 controls the luminance based on the input video signal, and the display failure due to the voltage drop caused by the resistance of the common electrode. Can be prevented and power consumption can be reduced.

(Display device according to an embodiment of the present invention)
Next, the display apparatus 200 to which the video signal processing apparatus 100 according to the embodiment of the present invention is applied will be described. Hereinafter, as the display device 200 according to the embodiment of the present invention, an organic EL display that is a self-luminous display device that emits light according to a current flowing through a light emitting element will be described as an example. Here, the organic EL element, which is a light emitting element included in the organic EL display, emits light according to the amount of current applied to the light emitting element because the IL characteristic (current-light emission amount characteristic) is linear. Needless to say, the display device 200 according to the embodiment of the present invention is not limited to an organic EL display.

  FIG. 12 is a block diagram showing the display device 200 according to the embodiment of the present invention. Note that the display device 200 shown in FIG. 12 is an embodiment of the display device according to the embodiment of the present invention, and it goes without saying that the embodiment of the present invention is not limited to the configuration of FIG. In the following description, it is assumed that the video signal input to the display device 200 is a digital signal used in digital broadcasting, for example. However, the video signal is not limited to the above, and is an analog signal used in analog broadcasting, for example. You can also

  Referring to FIG. 12, the display device 200 includes a video signal correction unit 202 and a video display unit 204.

  The display device 200 includes, for example, an MPU or the like, and can control a display device control unit (not shown) that can control the entire display device 200, and controls programs and calculation parameters used by the display device control unit. ROM (not shown) in which data is recorded, RAM (not shown) for temporarily storing a program executed by the display device control unit, data used for video signal correction in the video signal correction unit 202, and the like. A display device storage unit (not shown) that can be stored, a display device operation unit (not shown) that can be operated by the user, a receiving unit (not shown) that receives a video signal transmitted from a broadcasting station, and the like. May be. The display device 200 can connect the above-described constituent elements by, for example, a bus as a data transmission path.

  Here, examples of the display device storage unit (not shown) include a magnetic recording medium such as a hard disk and a nonvolatile memory such as a flash memory, but are not limited thereto. Examples of the display device operation unit include, but are not limited to, an operation input device such as a keyboard and a mouse, buttons, direction keys, or a combination thereof.

  The video signal correction unit 202 has, for example, the same configuration as the video signal processing device 100 shown in FIG. Therefore, the video signal correction unit 202 calculates an average luminance for each divided region based on the input video signal, sets a correction value according to the display position of the display screen, and adjusts (corrects) the gain of the video signal. can do.

  The video display unit 204 displays an image based on the video signal corrected by the video signal correction unit 202.

[Configuration Example of Video Display Unit 204]
The video display unit 204 includes a display unit 206, a row driving unit 208, a column driving unit 210, a power supply unit 212, and a display control unit 214.

  The display unit 206 corresponds to the display panel described above, and includes, for example, a plurality of pixels arranged in a matrix. For example, a display unit that displays an SD (Standard Definition) resolution image has at least 640 × 480 = 307200 (data lines × scanning lines) pixels, and these pixels are red, green, and blue for color display. In the case of being composed of sub pixels, it has 640 × 480 × 3 = 921600 (data lines × scanning lines × number of subpixels). Similarly, for example, a display unit that displays an HD (High Definition) resolution image has 1920 × 1080 pixels, and has 1920 × 1080 × 3 sub-pixels for color display. The display unit 206 includes a common electrode, for example, in units of rows, and each pixel is connected to the common electrode (for example, GND shown in FIG. 13 described above).

[Application example of sub-pixel (light-emitting element): When an organic EL element is provided]
When the light-emitting elements that constitute the sub-pixels of each pixel are organic EL elements, the IL characteristics (current-light emission amount characteristics) are linear, and light is emitted according to the amount of current applied to the light-emitting elements. Therefore, when an organic EL display is applied as the display device 200, the display device 200 shows the relationship between the amount of light of the subject indicated by the adjusted video signal and the amount of light emitted from the light emitting element of the display device 200. Since it can be linear, it is possible to display video and images faithful to the video signal.

  In addition, the display unit 206 includes a pixel circuit (for example, FIG. 13) for controlling the amount of voltage / current applied to each pixel. The pixel circuit includes, for example, a switch element and a drive element for controlling the amount of current by an applied scanning signal and a voltage signal, and a capacitor for holding the voltage signal. Further, the switch element and the drive element are composed of, for example, a thin film transistor. Here, FIG. 13 described above is an example of the pixel circuit, and in the example of FIG. 13, the transistor Tr1 (drive transistor) corresponds to the drive element. In FIG. 13, transistors corresponding to the switch elements are omitted.

  The row driver 208 and the column driver 210 apply voltage signals to a plurality of pixels included in the display unit 206 to cause each pixel to emit light. Here, one of the row driving unit 208 and the column driving unit 210 applies a voltage signal (scanning signal) that determines ON / OFF of a pixel, and the other applies a voltage signal (video signal) corresponding to an image to be displayed. Play the role of applying.

  Further, as a driving method of the row driving unit 208 and the column driving unit 210, for example, a dot-sequential driving scanning method in which light is emitted for each pixel arranged in the matrix form, and the pixels arranged in the matrix form for each column. Examples include a line sequential drive scanning method for emitting light, and a surface sequential drive scanning method for emitting light from all the pixels arranged in the matrix. The video display unit 204 of the display device 200 shown in FIG. 12 includes two drive units, a row drive unit 208 and a column drive unit 210, but the display device according to the embodiment of the present invention has one drive. Needless to say, it can be composed of parts.

  The power supply unit 212 supplies power to the row driving unit 208 and the column driving unit 210, and a voltage is applied to the row driving unit 208 and the column driving unit 210. In addition, the magnitude of the voltage applied by the power supply unit 212 to the row driving unit 208 and the column driving unit 210 varies according to the video signal corrected by the video signal correcting unit 202.

  The display control unit 214 is configured by, for example, an MPU and the like, and determines a pixel ON / OFF for one of the row driving unit 208 and the column driving unit 210 in accordance with the video signal corrected by the video signal correction unit 202. Is input to the pixel, and a video signal is input to the other. The display control unit 214 can also control the supply of power to the row driving unit 208 and the column driving unit 210 by the power supply unit 212 in accordance with the video signal corrected by the video signal correction unit 202.

  The display device 200 according to the embodiment of the present invention has a configuration as shown in FIG. 12, and can correct an input video signal and display a video based on the corrected video signal.

  As described above, the display device 200 according to the embodiment of the present invention displays the video signal correction unit 202 having the same configuration as the video signal processing device 100 according to the embodiment of the present invention and the image corresponding to the video signal. And a video display unit 204. Therefore, the display device 200 controls the luminance based on the input video signal, as in the video signal processing device 100, and prevents display failure due to voltage drop caused by the resistance of the common electrode and reduces power consumption. Can be planned.

  Further, the display device 200 is the same as the video signal processing device 100 described above according to the correction value setting method (for example, the first to fifth correction value setting methods described above) used in the video signal correction unit 202. There is an effect.

  In the above, the display device 200 has been described as an embodiment of the present invention, but the embodiment of the present invention is not limited to such a form. For example, the embodiments of the present invention can be applied to various self-luminous display devices such as organic EL displays, FEDs, and PDPs, and display devices having a separate light source such as an LCD. In addition, the embodiment of the present invention can be applied to a receiving apparatus that receives a television broadcast.

(Program related to display device 200)
In accordance with a program for causing a computer to function as the display device 200 according to the embodiment of the present invention, brightness is controlled based on an input video signal, and display failure is prevented and consumed due to a voltage drop caused by the resistance of the common electrode. Electric power can be reduced.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the video signal processing apparatus 100 according to the embodiment of the present invention illustrated in FIG. 5 and the display apparatus 200 illustrated in FIG. 12, the input video signal is described as a digital signal. . For example, the video signal processing device according to the embodiment of the present invention and the display device according to the embodiment of the present invention each include, for example, an A / D converter (Analog to Digital converter), and an input analog signal (video signal). May be converted into a digital signal, and the converted video signal may be processed. In addition, the video signal processing device according to the embodiment of the present invention and the display device according to the embodiment of the present invention may process an analog signal (video signal) by configuring each component with an analog circuit, for example. it can.

  12 includes the video signal correction unit 202 and the video display unit 204, but is not limited to this mode. For example, the display device 200 includes the video signal correction unit 202 and the video signal correction unit 202. The display control unit 214 included in the video display unit 204 may be integrated. Even in such a configuration, the display control unit can correct the input video signal and control the column driving unit, the row driving unit, the power supply unit, and the like based on the corrected video signal. The video can be displayed based on the corrected video signal as in the display device 200 according to the embodiment of the present invention.

  The configuration described above shows an example of the embodiment of the present invention, and naturally belongs to the technical scope of the present invention.

It is explanatory drawing for demonstrating the approach for prevention of the display defect by the voltage drop resulting from the resistance of the common electrode in the video signal processing apparatus which concerns on embodiment of this invention, and reduction of power consumption. It is explanatory drawing for demonstrating the outline | summary of the process in the video signal processing apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the outline | summary of the process in the video signal processing apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the outline | summary of the process in the video signal processing apparatus which concerns on embodiment of this invention. It is a block diagram which shows an example of the video signal processing apparatus which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the 1st correction value setting method in the correction value setting part which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the 2nd correction value setting method in the correction value setting part which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the 3rd correction value setting method in the correction value setting part which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the problem which the 4th correction value setting method in the correction value setting part which concerns on embodiment of this invention makes object. It is explanatory drawing for demonstrating the 4th correction value setting method in the correction value setting part which concerns on embodiment of this invention. 3 is a flowchart illustrating an example of a video signal processing method according to an embodiment of the present invention. It is a block diagram which shows the display apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows an example of a pixel circuit roughly. It is explanatory drawing which shows roughly the resistance value which arises in the common electrode of a display panel. It is explanatory drawing which shows schematically the pixel circuit in case the resistance value of the resistance which arises in a common electrode is large. It is explanatory drawing which shows an example of the display defect resulting from the voltage drop by resistance Ro which exists in a common electrode. It is explanatory drawing for demonstrating the problem in the apparatus using the prior art which reduces a brightness | luminance toward a screen edge part on the basis of the physical center point of a display screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Video signal processing apparatus 102 Average brightness calculation part 104 Correction center setting part 106 Correction value setting part 108 Gain adjustment part 200 Display apparatus 202 Video signal correction part 204 Video display part

Claims (8)

  1. An average luminance calculating unit that divides a display screen into a plurality of divided regions and calculates an average luminance for each of the divided regions based on an input video signal;
    Based on the average luminance for each of the divided areas, a divided area where a local common electrode voltage drop may occur in the display screen is determined, and the gain of the video signal corresponding to the determined divided area is determined based on the voltage drop. A correction center setting unit for setting a correction center position for setting to a predetermined value or less for preventing occurrence;
    A correction value setting unit that sets a correction value according to the display position of the display screen with the correction center position as a base point;
    A gain adjusting unit that adjusts the gain of the video signal based on the correction value;
    A video signal processing apparatus comprising:
  2.   2. The video according to claim 1, wherein the correction value setting unit sets a correction value that attenuates a gain of a video signal toward a screen end portion of the display screen using the correction center position as a base point. Signal processing device.
  3.   The video signal processing according to claim 2, wherein the correction value setting unit changes a gain attenuation rate of the video signal in accordance with a deviation amount of the correction center position with respect to a predetermined reference position. apparatus.
  4.   The correction value setting unit, when the correction center position set by the correction center setting unit changes from the first correction center position to the second correction center position, the correction value corresponding to the first correction center position The video signal processing apparatus according to claim 1, wherein the correction value is changed stepwise from a correction value to a correction value corresponding to the second correction center position.
  5.   The correction value setting unit further reduces the luminance of the video signal adjusted by the gain adjustment unit as the average luminance is larger than the threshold based on the average luminance for each of the divided regions and a predetermined threshold. The video signal processing apparatus according to claim 1, wherein a correction value is set.
  6. Dividing the display screen into a plurality of divided areas and calculating an average luminance for each of the divided areas based on an input video signal;
    Based on the average luminance for each of the divided areas, a divided area where a local common electrode voltage drop may occur in the display screen is determined, and the gain of the video signal corresponding to the determined divided area is determined based on the voltage drop. Setting a correction center position for setting to a predetermined value or less for preventing occurrence;
    Setting a correction value according to the display position of the display screen using the correction center position as a base point;
    Adjusting the gain of the video signal based on the correction value;
    A video signal processing method comprising the steps of:
  7. Dividing the display screen into a plurality of divided areas and calculating an average luminance for each of the divided areas based on an input video signal;
    Based on the average luminance for each of the divided areas, a divided area where a local common electrode voltage drop may occur in the display screen is determined, and the gain of the video signal corresponding to the determined divided area is determined based on the voltage drop. A step of setting a correction center position for setting to a predetermined value or less for preventing occurrence;
    Setting a correction value according to the display position of the display screen using the correction center position as a base point;
    Adjusting the gain of the video signal based on the correction value;
    A program that causes a computer to execute.
  8. A video signal correction unit for correcting the input video signal;
    A video display unit for displaying video on a display screen based on the video signal corrected by the video signal correction unit;
    With
    The video signal correction unit is
    An average luminance calculating unit that divides the display screen into a plurality of divided regions and calculates an average luminance for each of the divided regions based on an input video signal;
    Based on the average luminance for each of the divided areas, a divided area where a local common electrode voltage drop may occur in the display screen is determined, and the gain of the video signal corresponding to the determined divided area is determined based on the voltage drop. A correction center setting unit for setting a correction center position for setting to a predetermined value or less for preventing occurrence;
    A correction value setting unit that sets a correction value according to the display position of the display screen with the correction center position as a base point;
    A gain adjusting unit that adjusts the gain of the video signal based on the correction value;
    A display device comprising:
JP2008162486A 2008-06-20 2008-06-20 Video signal processing apparatus, video signal processing method, program, and display device Pending JP2010002770A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102208166A (en) * 2010-03-29 2011-10-05 索尼公司 Display device and electronic device
WO2013094104A1 (en) * 2011-12-20 2013-06-27 パナソニック株式会社 Display device and drive method for same
WO2018223498A1 (en) * 2017-06-08 2018-12-13 武汉华星光电技术有限公司 Dynamic backlight control and display method and device
US10475395B2 (en) 2017-06-08 2019-11-12 Wuhan China Star Optoelectronics Technology Co., Ltd Display method and device of dynamically controlling backlight
US10540134B2 (en) 2016-11-17 2020-01-21 Samsung Electronics Co., Ltd. Display apparatus and controlling method thereof

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102208166A (en) * 2010-03-29 2011-10-05 索尼公司 Display device and electronic device
JP2011209434A (en) * 2010-03-29 2011-10-20 Sony Corp Display device and electronic device
WO2013094104A1 (en) * 2011-12-20 2013-06-27 パナソニック株式会社 Display device and drive method for same
JPWO2013094104A1 (en) * 2011-12-20 2015-04-27 パナソニック株式会社 Display device and driving method thereof
US9595225B2 (en) 2011-12-20 2017-03-14 Joled Inc. Display device and method of driving the same
US10540134B2 (en) 2016-11-17 2020-01-21 Samsung Electronics Co., Ltd. Display apparatus and controlling method thereof
WO2018223498A1 (en) * 2017-06-08 2018-12-13 武汉华星光电技术有限公司 Dynamic backlight control and display method and device
US10475395B2 (en) 2017-06-08 2019-11-12 Wuhan China Star Optoelectronics Technology Co., Ltd Display method and device of dynamically controlling backlight

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