JP2008052068A - Plasma display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display device constituted to correct a white balance while suppressing luminance degradation on a low light emission times region side where electric power consumption is suppressed by APL and to correct the white balance to bluish white on a high light emission times region side where electric power consumption is not suppressed and the light emission times increase. <P>SOLUTION: The plasma display device is provided with an APL detection circuit 3 which detects light emission times, a microcomputer 2 which corrects the white balance by controlling the gain of primary color video signals of R, B, G, multipliers 11 to 13, etc., in which the microcomputer 2 and the multipliers 11 to 13, etc., lower the gain of R so as to satisfy a luminance ratio according to the detected light emission times on the basis of the G luminance of the luminance rates in R, G, B in the white balance regulated in the light emission times near the lower limit, and moreover control the gain of B so as not to lower the gain down to the gain satisfying the luminance ratios. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma display apparatus that performs color display by controlling the number of times of light emission corresponding to a plurality of (for example, R, G, B) primary color video signals, and in particular, has a white balance that varies depending on the number of times of light emission. The present invention relates to a white balance correction technique for correction.

  In a plasma display device using a PDP (Plasma Display Panel) that has become widespread in recent years, a plurality of subfields (for example, SF1 to SF8) weighted by the difference in the number of times of light emission (the number of times of light emission by applying a discharge sustaining pulse). Gradation is expressed by a so-called subfield method in which a subfield is selected for each pixel according to the amplitude of the signal.

  By the way, the total number of sustaining pulses applied to the PDP within one frame period, that is, the total number of sustaining pulses applied within each subfield period obtained by dividing one frame period (hereinafter referred to as “number of times of light emission”). ) Increases, the power consumption of the plasma display device increases. Therefore, in the plasma display device, for example, the number of times of light emission (total number of sustaining pulses) is limited in accordance with the average luminance level (Average Picture Level: hereinafter referred to as “APL”), the emission luminance is limited, and PDP The power consumption is suppressed. That is, the number of times of light emission is decreased as the APL increases. In general, this function is referred to as APC (Auto Power Control) or ABL (Automatic Brightness Limit). Here, for convenience, the minimum number of times of light emission (the total number of sustaining pulses) corresponding to the maximum APL (all white screen display) is represented by the symbol Nw.

On the other hand, the phosphors emitting the three primary colors (red, green, and blue) have different light emission efficiency and afterglow characteristics depending on the number of times of light emission. Therefore, even if the white balance is adjusted with the predetermined number of times of light emission, if the number of times of light emission is changed by APL, the white balance will be lost. A technique for solving this is disclosed, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2001-255843).
JP 2001-255843 A

  The above-mentioned patent document 1 detects the number of light emission from the APL of the image based on the three primary color video signals, or detects the number of light emission based on the display current at the time of image display based on the three primary color video signals, and the light emission number detection means. Disclosed is a plasma display device comprising white balance correction means for adjusting white balance by adjusting the gain of three primary color video signals corresponding to the number of times of light emission. According to the present technology, white balance can be maintained regardless of the number of times of light emission.

  By the way, in Patent Document 1, white balance is set at the number of times of light emission Nm at which the APL is small and the number of times of light emission is maximum, and the colored light emitted from the red phosphor R, green phosphor G, and blue phosphor B at this time, respectively. Using the luminance ratio of (R light, G light, B light) as a reference, the gain of the three primary color video signals is controlled in accordance with the variation in the number of times of light emission.

  Specifically. For example, when the APL increases and the average luminance increases, the number of times of light emission decreases in order to suppress the power consumption of the PDP by the APC (also referred to as ABL) function. When the number of times of emission decreases, as shown in FIG. 7 of Patent Document 1, red light (R light) and green fluorescence emitted by the red phosphor with respect to the luminance of blue light (B light) emitted by the blue phosphor. The brightness of the green light (G light) emitted by the body increases and the white balance is lost. Therefore, the white balance is corrected by lowering the gains Kr and Kg of the multipliers for the R primary color video signal and the G primary color video signal. For this reason, the luminance (brightness per unit area) decreases as the number of times of light emission decreases. Therefore, this reduction in luminance is maximized at the number of times of light emission Nw in all white display where power consumption is most suppressed. In other words, the peak luminance is reduced on a bright display screen where the APL is large due to the power consumption suppression by the APL, but the luminance is further reduced due to the white balance correction. The reduction in luminance due to the white balance correction is not sufficiently considered in Patent Document 1.

  On the other hand, in recent years, as a white color temperature, a bluish white color temperature (for example, 9000 to 10,000 K) is preferred. However, Patent Document 1 focuses on keeping the luminance ratio constant at the time of white balance setting with respect to the change in the number of times of light emission, and in the process of white balance correction, No consideration has been given to doing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a plasma display device that corrects white balance while suppressing a decrease in luminance on the low light emission frequency region side where power consumption is suppressed by APL. There is. Another object of the present invention is to provide a plasma display device in which white balance is corrected to a bluish white on the high light emission frequency region where the number of light emission increases without suppressing power consumption.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  In order to solve the above-described problem, in the present invention, the number of times of light emission detecting means for detecting the number of times of light emission, R, which is input in accordance with the detected number of times of light emission based on the white balance defined by the predetermined number of times of light emission. In a plasma display apparatus including a white balance correction unit that controls white gain by controlling the gain of the primary color video signals of G and B, the white balance correction unit is configured to emit light at a frequency near the lower limit that suppresses power consumption. Based on the G luminance of the luminance ratio of the primary color video signals of R, G, and B in a defined white balance, the gain of the primary color video signal of R is set as the luminance according to the number of times of light emission detected by the number of times of light emission detection. Control is performed so that the ratio is lowered to satisfy the ratio, and the gain of the primary color video signal of B is not decreased to the gain that satisfies the luminance ratio. It is assumed that.

  In the present invention, the white balance is set by the number of times of light emission near the lower limit for suppressing power consumption, and the luminance ratio of the R, G, B light at this time is used as a reference. Therefore, for example, it is possible to suppress a decrease in luminance in a low light emission frequency region where power consumption is suppressed by APL. That is, while suppressing power consumption during all white display, the luminance can be improved compared to the conventional case, and a brighter white display can be obtained. As the number of times of light emission increases, gain control is performed by the white balance correction means, and when correcting the white balance, the gain of the R primary color video signal is lowered to satisfy the luminance ratio, and the B Since the control is performed so that the gain of the primary color video signal is not lowered to the gain satisfying the luminance ratio, it can be corrected to a bluish white balance. As a result, a refreshing screen with a blue tint can be enjoyed.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  According to the present invention, for example, white balance is corrected while suppressing a decrease in luminance on the low light emission frequency region where power consumption is suppressed by APL, and bluish on the high light emission frequency region side where power consumption is not suppressed. A plasma display device in which white balance is corrected to white can be provided.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. In each drawing, elements having common functions are denoted by the same reference numerals, and repeated description of elements once described is omitted.

  In addition, the “number of times of light emission” referred to below refers to the number of times of light emission generated by the discharge sustain pulse applied to the PDP within one frame period, and is equal to the total number of discharge sustain pulses within one frame period. In this sense, hereinafter, the same meaning as the total number of sustaining pulses is used.

  Before touching the embodiment of the present invention, first, the luminance characteristic with respect to the number of times of light emission of the PDP phosphor will be described with reference to FIG.

  FIG. 7 is a diagram showing the relationship between the number of times of light emission and the luminance of the phosphors of the three primary colors of red, green and blue. FIG. 7 (a) shows the relationship between the number of times of light emission and the luminance. The unit light emission luminance characteristic by the decrease in energy conversion efficiency is shown. In addition, the brightness | luminance of the vertical axis | shaft of FIG.7 (b) is the value which normalized the brightness | luminance per unit light emission with the light emission brightness per unit in case energy conversion efficiency is the highest.

  As shown in FIG. 7A, the luminances of the three primary colors of red (R), green (G), and blue (B) become saturated as the number of times of light emission increases. This is because the afterglow characteristics of the phosphors of red, green and blue, in other words, the energy conversion efficiency of the phosphor with respect to excitation by ultraviolet rays decreases as the number of times of light emission increases as shown in FIG. It happens.

  In the plasma display device, the power consumption is suppressed by APC, and the number of times of light emission is the maximum number of times of light emission Nm (Q point in FIG. 7) in the case of a dark image in which APL is small and power consumption is not suppressed. When the power consumption is suppressed most gradually as it increases, the minimum number of times of light emission Nw (point P in FIG. 7) is reached.

  Here, as in the conventional case, in FIG. 7, for example, if the white balance is set at the Q point of the maximum number of light emission Nm, the white balance value at that time is the red, green and blue phosphors at the Q point. It is determined by the luminance ratio of the emitted color light. However, when displaying a video signal with a high APL, the number of times of light emission is reduced in order to reduce power consumption as described above.

  Accordingly, for example, at the point P of the minimum number of times of light emission Nw, as shown in FIG. 7B, the energy conversion efficiency of the phosphor with respect to excitation by ultraviolet rays increases, so the reduction rate of the energy conversion efficiency is green> red> blue. If it is, the luminance is higher in the order of green> red> blue than the Q point. That is, since the luminance ratio of the color light emitted from the red, green, and blue phosphors at the point P is different from the set value at the point Q, there is a difference in white balance between the points Q and P.

  For this reason, conventionally, the white balance is corrected by lowering the amplitudes of the R primary color video signal and the G primary color video signal with respect to the B primary color video signal. However, because of this white balance correction, green light with high visibility is reduced and luminance is lowered. This decrease in luminance is maximized at the number of times of light emission Nw in all white display where power consumption is most suppressed. In other words, the peak luminance decreases on a bright display screen where the APL increases due to power consumption suppression by the APL, but further decreases in luminance due to white balance correction.

  Therefore, in the present invention, the white balance is set at a location where the number of times of light emission is low, for example, the point P of the minimum number of times of light emission Nw, where power consumption is suppressed. As a result, a decrease in luminance due to the white balance correction is reduced on the point P side, so that a brighter image can be obtained as compared with the conventional case while suppressing to a predetermined power consumption. Note that the white balance setting at the point P is performed by, for example, a phosphor emission characteristic corresponding to the three primary colors or a so-called optical filter disposed on the front side of the PDP.

  Embodiments of the present invention will be described below.

(First embodiment)
FIG. 1 is a block diagram schematically showing the main part of the plasma display device according to the first embodiment of the present invention.

  In FIG. 1, 11 to 13 are multipliers, 2 is a microcomputer (microcomputer) as an arithmetic control unit, 3 is an APL detection circuit, 41 to 43 are gamma correction circuits (γ correction circuit), and 6 is a panel drive circuit. ing. In the main part of the plasma display device according to the present embodiment, the APL detection circuit 3 functions as a light emission number detecting means for detecting the number of light emission together with the microcomputer 2. Further, the microcomputer 2 and the multipliers 11 to 13 control the gains of the primary color video signals of R, G, and B inputted according to the detected number of times of light emission based on the white balance defined by the predetermined number of times of light emission. Function as white balance correction means for correcting white balance. This will be specifically described below.

  The gamma correction circuits 41 to 43 perform non-linear gamma (γ) correction on the input three primary color video signals R, G, and B so as to match the input-luminance characteristics of a PDP (not shown). The white balance correction circuit includes the microcomputer 2, the APL detection circuit 3, and the multipliers 11 to 13, and corrects the white balance in the video signal of the three primary colors after the gamma correction. The panel drive circuit 6 drives a PDP (not shown) based on the three primary color video signals whose white balance has been corrected by the white balance correction circuit, and displays a color image on the PDP screen.

  The multipliers 11 to 13 change the gain of the corresponding video signal after gamma correction according to multiplication coefficients (amplitude coefficients) Kr, Kg, and Kb supplied from the microcomputer 2 to be described later, thereby adjusting the white balance. to correct.

  The panel drive circuit 6 drives a PDP (not shown) based on the video signals from the multipliers 11 to 13 whose white balance has been corrected, and displays an image on the PDP screen.

  The APL detection circuit 3 detects APL (average luminance level: also referred to as display rate) of an image to be displayed from the three primary color video signals R, G, and B after gamma correction, and supplies the detected APL to the microcomputer 2 described later.

  The microcomputer 2 is an arithmetic control unit that performs predetermined arithmetic control processing while referring to arithmetic expressions and tables stored in advance in a memory (not shown) according to a program stored in a ROM (Read Only Memory) (not shown). Here, the memory (not shown) emits light based on an APL-light emission number correspondence table (not shown) in which the number of light emission times defined for each APL (average luminance level: display rate) is described, or based on the minimum light emission number Nw. A brightness ratio calculation expression (details will be described later) for deriving a brightness ratio α (described later) using the number N as a parameter, a multiplication coefficient calculation expression (details will be described later) for calculating a multiplication coefficient from the calculated brightness ratio, and the like are stored in advance. It shall be. The microcomputer 2 calculates the multiplication coefficients Kr, Kg, Kb of the multipliers 11 to 13 using the APL-light emission count correspondence table, the luminance ratio calculation formula, the multiplication coefficient calculation formula, and the like, and the multiplication coefficients Kr, Kg. , Kb are supplied to the corresponding multipliers 11 to 13 respectively.

  As described above, the plasma display apparatus according to the first embodiment performs gamma correction on the input video signals R, G, and B by the gamma correction circuits 41 to 43. Next, by changing the gain of the multipliers 11 to 13 according to the multiplication coefficients Kr, Kg, and Kb given from the microcomputer 2, the amplitude of each video signal after the gamma correction is varied, and the white balance is corrected. Then, an image is displayed on a PDP (not shown) via the panel drive circuit 6.

  The microcomputer 2 performs white balance correction processing shown in FIG. 2 in order to perform optimum white balance correction according to the input video signal by the multipliers 11 to 13. FIG. 2 is a flowchart showing an example of white balance correction processing according to the present embodiment.

  As shown in FIG. 2, the microcomputer 2 acquires APL (average luminance level: display rate) from the APL detection circuit 3 in step S1. Next, in step S2, the number of times of light emission N is calculated from the acquired APL with reference to the APL-light emission number correspondence table (not shown). In step S3, the microcomputer 2 calculates an increase / decrease rate of the luminance ratio of R, G, B (red, green, and blue) due to increase / decrease in energy conversion efficiency from the calculated number of times of light emission N, and a luminance ratio calculation formula (described later in detail). ) To calculate. Then, a multiplication coefficient K (Kr, Kg, Kb) that achieves a predetermined white balance is calculated from the increase / decrease rate using a multiplication coefficient arithmetic expression (details will be described later), and supplied to the multipliers 11 to 13. . In this embodiment, Kg is constant because the green emission luminance is used as a reference. Next, in step S4, the calculated multiplication coefficients Kr, Kg, Kb are sent and set to the multipliers 11 to 13, and the multipliers 11 to 13 perform optimum white balance correction.

  Next, the process of calculating the luminance ratio and the multiplication coefficient will be described with reference to FIGS. FIG. 3 is a diagram showing the luminance ratio of each of the three primary color phosphors with respect to the number of times of light emission, with blue as a reference. FIG. 4 is a diagram for explaining the multiplication coefficients of the three primary colors in the white balance correction circuit.

  In FIG. 3, the horizontal axis represents the number of times of light emission N, and the vertical axis represents the luminance ratio α. The luminance ratio α is normalized (Lr / Lwr, Lg / Lwg, Lr / Lwr, Lg / Lwg) with the light emission luminance (Lwr, Lwg, Lwb) of each color light at the time of setting the white balance. Lb / Lwb) and expressed in relative luminance with reference to blue. Specifically, the luminance ratio of red to blue is defined by (Lr / Lwr) / (Lb / Lwb), and the luminance ratio of green to blue is defined by (Lg / Lwg) / (Lb / Lwb). The

  Here, since the white balance is set at the minimum number of times of light emission Nw, the luminance ratio α is 1 at the point P. In addition, the blue phosphor has better linearity than other phosphors in the luminance characteristics with respect to the number of times of light emission, and can be regarded as almost constant. When blue is used as a reference, as the number of times of light emission increases from the number of times of light emission Nw, the luminance ratio α between green and red gradually decreases as is apparent from FIG. The characteristics of the luminance ratio α can be linearly approximated as a first order approximation between the number of times of light emission Nw−Nm. At this time, the green luminance ratio αg and the red luminance ratio αr can be expressed by the following equations.

αg = (1−αgo) N / Nw + αgo (Formula 1)
αr = (1−αro) N / Nw + αro (Formula 2)
Here, αgo and αro are the luminance ratio α at the point where the linear approximate luminance ratio characteristics of each color intersect on the vertical axis.

  As apparent from FIG. 3, as the number of times of light emission N increases from the minimum number of times of light emission Nw, the luminance ratios αr and αg gradually decrease, and the white balance is lost. Therefore, the gain of the multiplier 12 for the G primary color video signal is not changed, and the multiplier 11 for the R primary color video signal and the multiplier 13 for the B primary color video signal are set so that the luminance ratio is the same as when white balance is set. If the gain is reduced, the white balance can be maintained. At this time, the gain of the multiplier 13 for the B primary color video signal is not lowered until the luminance ratio becomes the same as that at the time of setting the white balance. Thus, if the amount of decrease in the gain of the multiplier 13 for the primary color B video signal is reduced, it is possible to correct the bluish white balance and enjoy a bluish refreshing screen. become.

  Next, calculation of the gain coefficient of each multiplier corresponding to the number of times of light emission will be described with reference to FIG.

  In FIG. 4, the horizontal axis represents the number of times of light emission N, and the vertical axis represents the multiplication coefficient K. The multiplication coefficient K is defined using the brightness ratio α calculated as described above. When the luminance ratio is the same as when white balance is set, the multiplication coefficient Kg of the green multiplier 12 is set to 1, and the multiplication coefficient Kr of the red multiplier 11 and the multiplication coefficient Kb ′ of the blue ′ color multiplier 13 are It can be expressed by a formula. Here, in order to distinguish from a multiplication coefficient Kb (described later) of the blue multiplier 13 applied according to the present invention, it is expressed as a blue 'color multiplication coefficient Kb'.

Kr = αg / αr = [(1-αgo) N + αgoNw]
/ [(1-αro) N + αroNw] (Formula 3)
Kb ′ = αg / αb = (1−αgo) N / Nw + αgo (Formula 4)
When the gain coefficient K (Kr, Kg = 1, Kb ′) based on the number of times of light emission N is set in the corresponding multiplier, the white balance having the same luminance ratio as that at the time of setting the white balance can be corrected. However, a white balance with a blue tint on the Q side cannot be achieved.

  Therefore, in the present embodiment, in order to correct the bluish white balance, the actually set blue multiplication coefficient Kb (represented by a linear expression here) is used as the green multiplication coefficient Kg and blue ′. It is set to a value between the color multiplication coefficient Kb ′. Thus, if the gain coefficient Kb is made larger than the gain coefficient Kb ′ and the amount of reduction in the gain of the multiplier 13 for the primary color B video signal is reduced, a white balance with a bluish color on the Q side can be achieved. Become. The mathematical expression expressing the gain coefficient Kb is stored in advance in a memory (not shown) of the microcomputer 2. As described above, the multiplication coefficients K (Kr, Kg = 1, Kb) of the three primary colors in the white balance correction circuit are obtained using, for example, the multiplication coefficient arithmetic expression (Kb and Kr in Expression 3).

  Here, the linear expression shown in FIG. 3 is determined by the phosphor, and is determined if the phosphor is determined. Accordingly, a gain coefficient calculation formula (see FIG. 4) for calculating the gain coefficient is programmed in the microcomputer 2 in advance, and the multiplication coefficient K for each number of times of light emission is calculated using the program.

  In the present embodiment, the luminance ratio and the gain coefficient are calculated using arithmetic expressions, but the present invention is not limited to this, and it goes without saying that it may be calculated using a conversion table. Absent.

  Next, the luminance ratio of each of the three primary color phosphors corrected by the white balance correction circuit based on each multiplication coefficient K calculated as described above will be described with reference to FIG. FIG. 5 is a diagram showing the luminance ratio of each of the three primary color phosphors corrected by the white balance correction circuit at each light emission frequency.

  As shown in FIG. 5, the phosphors of red, green and blue (three primary colors) satisfy the luminance ratio with the increase in the number of times of light emission in order to correct the white balance with a bluish tint. The blue gain is controlled so as not to decrease to a gain satisfying the luminance ratio.

  As described above, according to the plasma display device according to the present embodiment, the APL detection circuit 3 that detects the number of times of light emission, the microcomputer 2 that corrects the white balance by controlling the gains of the primary color video signals of R, G, and B, and By providing the multipliers 11 to 13 and the like, the white balance is set by the number of times of light emission near the lower limit for suppressing power consumption, and the luminance ratio of the R, G, and B light at this time is used as a reference. While suppressing power consumption at the time of display, the luminance can be improved as compared with the conventional case, and a brighter white display can be enjoyed.

  Further, when gain control is performed as the number of times of light emission increases and white balance is corrected, the gain of R is lowered so as to satisfy the luminance ratio, and the gain of B is reduced to a gain satisfying the luminance ratio. Since it is controlled so as not to be lowered, it is possible to correct the white balance with a bluish color, and thereby it is possible to enjoy a refreshing screen with a bluish color.

  In the above description, the blue multiplication coefficient Kb is set to a value between the green multiplication coefficient Kg and the blue 'color multiplication coefficient Kb'. However, the present invention is not limited to this. It goes without saying that the same value as the multiplication coefficient at the time of balance setting may be used.

  Further, as a modification of the present embodiment, in the range from the minimum light emission number Nw to a predetermined light emission number, the gain coefficient Kb is set to Kb ′ so that the white balance of the luminance ratio at the time of white balance setting is corrected to a predetermined value. From the number of times of light emission to the maximum number of times of light emission Nm, the blue multiplication coefficient Kb is set to a value between the green multiplication coefficient Kg and the blue 'color multiplication coefficient Kb', or the white balance is set without reducing the gain. You may make it be the same value as the multiplication coefficient of time. In this way, only in a region where the average luminance level (APL) is small, the white balance of the pixel having a high peak luminance can be set to a bluish color temperature, and a refreshing screen can be enjoyed. Such a modification can be dealt with by slightly changing the flow of the microcomputer 2 and will not be described in detail.

(Second Embodiment)
FIG. 6 is a block diagram schematically showing the main part of the plasma display device according to the second embodiment of the present invention.

  In FIG. 6, the white balance correction circuit includes a microcomputer 2, a current detection circuit 5, a light emission number control circuit 7, and multipliers 11 to 13. The white balance correction circuit includes the first embodiment shown in FIG. 1 described above. A current detection circuit 5 is provided in place of the APL detection circuit 3 in the embodiment, and the current detection circuit 5 detects the consumption current (display current) of the panel drive circuit 6, that is, the average of the first embodiment A display current corresponding to the luminance level (display rate) is detected, and the microcomputer 2 calculates the multiplication coefficient accordingly. In the present embodiment, the microcomputer 2 receives the output from the current detection circuit 5 to control the number of times of light emission of each phosphor. For example, the power consumption of the plasma display device becomes smaller than a predetermined value. As described above, the number of times of light emission is controlled via the light emission number control circuit 7.

  That is, the current detection circuit 5 detects the current consumed by the panel drive circuit 6, converts it into a voltage value, and feeds it back to the microcomputer 2. The microcomputer 2 determines the number of times of light emission from the light emission number control circuit 7 according to the voltage value. Reading and setting of the number of times of light emission are performed. Then, the microcomputer 2 calculates the change in the luminance ratio according to the increase / decrease rate of the energy conversion efficiency according to the set number of times of light emission, and calculates the multiplication coefficient K (Kr, Kg, Kb). The multiplication coefficients Kr, Kg, and Kb are multiplied by the video signals R, G, and B by the multipliers 11, 12, and 13, and the signal amplitude is adjusted to correct the white balance with a bluish color. it can.

  As described above, according to the plasma display device of the present embodiment, the current detection circuit 5 that detects the number of times of light emission, the microcomputer 2 that corrects the white balance by controlling the gain of the primary color video signals of R, G, and B, and multiplication. By providing the devices 11 to 13 and the like, as in the first embodiment, the brightness can be improved compared to the conventional one while suppressing the power consumption at the time of all white display, and a brighter white display can be achieved. In addition to being able to enjoy it, it can be corrected to a bluish white balance, thereby enabling a refreshing bluish screen to be enjoyed.

  Furthermore, according to the plasma display device of the present embodiment, it can be widely applied to, for example, a plasma display device that does not have an APL detection circuit as compared with the first embodiment. In addition, the present invention can be applied to a CRT or the like.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention relates to a plasma display apparatus that performs color display by controlling the number of times of light emission corresponding to R, G, and B primary color video signals, and more particularly to a white balance correction technique for correcting white balance that varies depending on the number of times of light emission. Is available.

It is the block diagram which showed typically the principal part of the plasma display apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows an example of a white balance correction process in the plasma display apparatus which concerns on the 1st Embodiment of this invention. In the plasma display apparatus which concerns on the 1st Embodiment of this invention, it is the figure which showed the luminance ratio in each frequency | count of light emission of the phosphor of three primary colors on the basis of blue. FIG. 4 is a diagram for explaining respective multiplication coefficients of three primary colors in a white balance correction circuit in the plasma display device according to the first embodiment of the present invention. In the plasma display apparatus which concerns on the 1st Embodiment of this invention, it is the figure which showed the luminance ratio in each frequency | count of light emission of the phosphor of the three primary colors corrected by the white balance correction circuit. It is the block diagram which showed typically the principal part of the plasma display apparatus which concerns on the 2nd Embodiment of this invention. In the plasma display device studied as the premise of the present invention, the luminance characteristics with respect to the number of times of light emission of each of the three primary colors of red, green and blue ((a) is the relationship between the number of times of light emission and the luminance, and (b) is the energy conversion efficiency. It is the figure which showed the unit light emission luminance characteristic by decrease.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11-13 ... Multiplier, 2 ... Microcomputer, 3 ... APL detection circuit, 41-43 ... Gamma correction circuit, 5 ... Current detection circuit, 6 ... Panel drive circuit, 7 ... Light emission frequency control circuit.

Claims (4)

In the plasma display device,
A light emission number detecting means for detecting the number of light emission times, and controlling the gain of the primary color image signals of R, G, B inputted according to the detected light emission number with reference to the white balance defined by the predetermined light emission number. And white balance correction means for correcting the white balance,
The white balance correction means uses the G luminance at the luminance ratio of the primary color video signals of R, G, B in the white balance defined by the number of emission near the lower limit for suppressing power consumption as a reference, and detects the number of emission times. The gain of the primary color video signal of R is lowered so as to satisfy the luminance ratio, and the gain of the primary color video signal of B is not lowered to the gain satisfying the luminance ratio in accordance with the number of times of light emission detected in step (b). The plasma display apparatus is characterized by being controlled as follows. The plasma display apparatus according to claim 1, wherein
2. The plasma display apparatus according to claim 1, wherein the white balance correction means controls so that only the gain of the R primary color video signal satisfies the luminance ratio. The plasma display device according to claim 2, wherein
The white balance correction means corresponds to a calculation control unit that calculates a multiplication coefficient corresponding to a luminance ratio of the primary color video signals of R, G, and B, and a multiplication coefficient supplied from the calculation control unit, respectively. A plasma display apparatus comprising: a multiplier for R, G, B that varies a gain of a video signal after gamma correction. The plasma display device according to claim 3, wherein
The arithmetic control unit obtains APL from the light emission number detecting means, calculates the light emission number from the acquired APL with reference to the APL-light emission number correspondence table, and increases or decreases energy conversion efficiency from the calculated light emission number. An increase / decrease rate of the luminance ratio of R, G, B is calculated using a luminance ratio calculation formula or a luminance ratio conversion table, and a multiplication coefficient that gives a predetermined white balance is calculated from the increase / decrease rate. A plasma display apparatus, wherein a coefficient is set for each multiplier.

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