KR100484197B1 - Auto Power Controlling method of PDP and apparatus therefor - Google Patents

Abstract

The present invention relates to an auto power control (APC) method of a plasma display panel (PDP), and more particularly, to efficiently reduce power consumption by controlling brightness using human visual characteristics. It relates to a power control method and a device suitable therefor.

The power control method of the PDP according to the present invention is a method of measuring the average brightness level of the input image, and controlling the power consumption of the plasma display panel (PDP) according to the measured average brightness level, the average brightness of the input image Measuring the level; Setting a power consumption level corresponding to the measured average brightness level and displaying an input image on the PDP according to the set power control level; Comparing the measured average brightness level with a previous average brightness level in a predetermined first period; And adjusting the power control level so that the power consumption of the PDP becomes smaller if the previous average brightness level is equal to the current average brightness level.

In the power control method according to the present invention, if the average luminance level of the input image remains constant for a predetermined time, the luminance of the displayed image is lowered, that is, the number of sustain pulses is reduced, thereby effectively reducing the power consumption of the PDP. .

Description

Power control method of plasma display panel and apparatus suitable therefor {Auto Power Controlling method of PDP and apparatus therefor}

The present invention relates to an auto power control (APC) method of a plasma display panel (PDP), and more particularly, to reduce power consumption by controlling brightness using human visual characteristics. A control method and a device suitable therefor.

PDP is a display device that uses a plasma discharge with a relatively high pressure Ne (Ne) or helium (He) gas as a base gas.

In the case of PDP that implements 256 gray levels for R / G / B, one frame is generally composed of eight subfields, and each subfield has 2 ⁰ , 2 ¹ , 2 ² , 2 ³ , It is configured to have a weight of 2 ⁴ , 2 ⁵ , 2 ⁶ , 2 ⁷ . The weight for each subfield represents the sustain discharge period of each subfield.

The gray level in the PDP is determined by the duration of the sustain discharge. Therefore, a large number of sustain discharges are required for the expression of high gradation, and in this case, a large amount of sustain discharge current flows, thereby increasing power consumption.

The power consumed by the PDP can be divided into components consumed by the power supply unit and components consumed by the driver and panel. The amount of power consumed by the driver and the panel varies greatly depending on the input video signal. The components consumed by the power supply are about 20% of the total power consumption, depending on the efficiency of the power supply. Therefore, since most of the total power consumption is consumed by the driver and the panel, power consumption of the driver and the panel becomes the main object of power control.

The power consumed by the driver and the panel in the PDP is linearly proportional to the average luminance level of the displayed image and the number of sustain discharge pulses.

Therefore, there are two methods of controlling power in the PDP. One method is to change the image signal applied to the PDP panel to lower the average luminance level, and the other is to change the configuration of the subfield to lower the number of sustain discharge pulses.

The former methods are disclosed in 2002-89324 (published November 29, 2002), 2001-61002 (published July 7, 2001), 2000-44751 (published July 15, 2000), and 2000- 33616 (published on June 15, 2000), published 1998.61650 (released on July 25, 1998), published 1998-61652 (released on July 25, 1998), published on 1998-75492 (released on November 11, 1998). 16 publications).

For example, Japanese Patent Laid-Open No. 2001-61002 discloses a technique in which the average luminance level of an input video signal is greater than or equal to a predetermined value so that its level is reduced and applied to the PDP panel.

The latter method is a method of adjusting the configuration of a subfield and the number of sustain pulses per frame according to the average brightness level of a video signal. EP 99101977.9, Japanese Patent Application Laid-Open No. 2001-64130) 2001. July 9), Publication 2000-3326 (January 15, 2000), Publication 2000-1748 (January 15, 2000), Publication 2000-8125 (May 15, 2000), Japanese Patent Application Laid-Open No. 1998-11725 (published Nov. 16, 1998) and Japanese Patent Laid-Open No. 2000-22614 (published Apr. 25, 2000).

For example, Japanese Patent Laid-Open No. 2000-3326 discloses an apparatus for detecting an average luminance level of an input video signal and adjusting the configuration of each subfield and the number of sustain pulses according to the value.

As described above, if the average luminance level of the input image is generally lower, the average luminance of the image displayed through the PDP panel is increased. On the contrary, when the luminance level is high, the contrast is limited while the power consumption is reduced, thereby improving the contrast. It is called (Peak Luminance Enhancement). In PLE, the average luminance level is measured in units of frames. When the average luminance level of the input image is changed, the configuration of the subfield and the number of sustain pulses are changed.

On the other hand, the visual characteristics of humans have a characteristic that the change is not easily recognized even if the brightness is slightly reduced when the same average brightness level is maintained on the screen. Therefore, by using this, it is possible to efficiently reduce power consumption by lowering the brightness level slightly while the average brightness level lasts.

An object of the present invention is to provide a power control method for efficiently reducing power consumption by using human visual characteristics.

Another object of the present invention is to provide an apparatus suitable for the above power control method.

PDP power control method according to the present invention for achieving the above object

In the method of measuring the average brightness level of the input image, and controlling the power consumption of the plasma display panel (PDP) according to the measured average brightness level,

Measuring an average brightness level of an input image;

Setting a power consumption level corresponding to the measured average brightness level and displaying an input image on the PDP according to the set power control level;

Comparing the measured average brightness level with a previous average brightness level in a predetermined first period; And

And adjusting the power control level so that the power consumption of the PDP is reduced if the previous average brightness level is the same as the current average brightness level.

The power control method may measure the average luminance level of the input image at a predetermined second period, and if the average luminance level of the input image is greater than the previous average luminance level, the power consumption level corresponds to the average luminance level of the input image. It is desirable to set the power control level to allow a lower power consumption as far as possible.

Power control apparatus of the PDP according to the present invention to achieve the above another object

In the apparatus for measuring the average brightness level of the input image, and controlling the power consumption of the plasma display panel (PDP) according to the measured average brightness level,

An ASL calculator configured to measure an average luminance level ASL of an input image;

A memory for storing a lookup table having a range of power consumption levels corresponding to the measured average brightness level;

Obtain a range of power consumption levels corresponding to the measured average brightness level with reference to the memory, compare the measured average brightness level with a previous average brightness level at a predetermined first predetermined period, and then obtain a previous average brightness level And an APC determination unit that adjusts the power control level in a range of power consumption levels corresponding to the average brightness level measured so that the power consumption of the PDP becomes smaller when the current average brightness level is the same.

According to the power control method according to the present invention, if the average luminance level of the input image is kept constant for a predetermined time, the luminance of the displayed image is lowered, that is, the number of sustain pulses is reduced, thereby effectively reducing the power consumption of the PDP. .

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the present invention.

Various methods for the construction of a PDP are known, but in order to achieve a thin shape, it is often adopted to form an airtight container that encloses opposing front glass substrates and rear glass substrates with sealing glass to contain discharge gas. Usually, low-cost soda-lime glass is used as the front and back glass substrates.

In a PDP having a small number of display cells, a spacer or anterior or rear surface of the display panel may be used to prevent error discharge or color penetration between adjacent cells or to withstand pressure differences between panels and to define the distance between electrodes for discharge. A partition is required between the glass substrates. The space surrounded by the partition wall and the front and rear glass substrates becomes one display cell. Phosphors are applied as layers in the display cells, and the phosphor layers generate visible light of respective colors by ultraviolet rays generated by the discharge.

It is convenient to form a plurality of cells at the intersections of line-shaped row and column electrodes when dividing the discharge electrodes into rows and columns, respectively.

A plurality of cells are independently selected as two electrode groups as the row electrode and the column electrode as the first or second electrode group. Therefore, since the 1st and 2nd electrode group should just be a selectable structure, it does not matter what kind.

In the PDP, a discharge is obtained by adjusting a voltage applied between a row electrode and a column electrode of a cell constituting a pixel, and the amount of discharged light is adjusted by changing the length of discharge time in the cell.

Among such PDPs, in particular, surface-discharge AC-type PDPs generate images by causing surface discharge as a voltage control applied to row electrodes and column electrodes as described above, and are known, for example, from Japanese Unexamined Patent Publication No. 7-140922. It is.

Fig. 1 shows the construction of a general surface discharge type AC PDP and is disclosed in Japanese Patent Laid-Open No. 7-140922.

The surface discharge PDP panel 100 includes a front glass substrate 102 and a front glass substrate 102 positioned parallel to the front glass substrate 102 at a predetermined distance, and the front and rear glass substrates 102, The partition wall 110 arranged between the two glass substrates to keep the two glass substrates in parallel and to isolate the cells to form a discharge space, and the partition wall 110 on the opposite surface of the rear glass substrate 103 of the front glass substrate 102. Back of the first row electrode 104 as the common electrodes X1 to Xn, the second row electrode 105 as the scan electrodes Y1 to Yn, and the front glass substrate 102, which are arranged in parallel to each other so as to be perpendicular to each other. A dielectric layer 106 formed under the opposing surface of the glass substrate 103 to limit the discharge current at the time of discharging, and the back glass between the magnesium oxide (MgO 107 and the respective divisions 110) coated on the dielectric layer 106. The first and second row electrodes 104 and 105 are parallel to the partition wall 110 on the opposite surface of the substrate 103 to the front glass substrate 102. ) Is formed on the column electrodes 108 (W1 to Wn), which form a matrix, and is discharged, and is applied on the rear glass substrate 103 inside the discharge space, and is excited by ultraviolet rays generated by the discharge of each cell. And a fluorescent layer 109 for generating visible light, wherein the discharge cells at the intersections of the first and second row electrodes 104 and 105 facing each other with the orthogonal column electrodes 108 become pixels. The discharge cells are separated by the partition wall 110.

In the surface discharge plasma display panel 100 as described above, its operation is performed by applying voltage pulses alternately between the first row electrode 104 and the second row electrode 105 to invert the polarity every half cycle. Causes the cell to emit light.

As the color display, the phosphor layer 109 formed in each cell is excited by the ultraviolet rays from the discharge and emits light. Since the first row electrode 104 and the second row electrode 105 for discharging for display are covered with the dielectric layer 106, once discharge occurs between the electrodes of each cell, electrons or ions generated in the discharge space It moves in the direction of the applied voltage and accumulates in the dielectric layer 106.

The charges such as electrons and ions accumulated on the dielectric layer 106 are called wall charges. Since the electric field formed by this wall charge acts in the direction of weakening the applied electric field, the discharge disappears rapidly with the formation of the wall charge.

When the electric field whose polarity is reversed after the discharge is applied is applied, the electric field forming the wall charge and the applied electric field overlap so that the discharge can be performed even at a lower applied voltage than the previous discharge. After that, it is possible to maintain the discharge by inverting this low voltage every half cycle. This function is called a memory function. The discharge maintained at a low applied voltage by using this memory function is called sustain discharge (oil dielectric), and the voltage pulse applied to the first row electrode 104 and the second row electrode 105 every half cycle is called a sustain pulse. Call.

This sustain discharge lasts as long as the sustain pulse is applied until the wall charge disappears, and erasing the wall charge is called erasing.

The wall charge dissipation is erased when an erase pulse is applied to the first row electrode 104, while the wall charge is first formed on the dielectric layer 106. This is called recording. This recording is made possible by applying the reset pulses which are out of phase and synchronized to the first row electrode 104 and the second row electrode 105.

The following describes the gray scale display method of the AC display.

Gray scale display of an AC plasma display panel and a method of driving the panel are well known, for example, from Japanese Patent Laid-Open No. 7-160218.

FIG. 2 shows the structure of a subframe in a surface discharge type AC plasma display panel, and FIG. 3 is a voltage waveform diagram in a first subfield showing a method of driving the surface discharge type AC plasma display panel of FIG. It is disclosed in Japanese Patent Application Laid-Open No. 7-160218.

First, in FIG. 2, one frame is a time for outputting one picture on the screen, which is about 16.7 msec (60 Hz) in the case of NTSC.

In FIG. 2, the display line is a line in a row direction consisting of the first and second row electrodes of the AC plasma display panel, and the horizontal direction represents the passage of time. One frame is divided into several sub-fields, and each subfield is composed of a reset period, an addressing period, and a sustain period, respectively. For example, when 256 gradations are displayed, there are eight subfields in one frame, and the time of the sustain discharge period of each subfield is 2n (n is 0 to 7).

The entire screen includes a reset pulse for inputting a digital image signal to the first and second row electrodes and column electrodes of each cell, a scan pulse for scanning, a sustain pulse for maintaining a discharge, and a discharged cell. It is obtained by driving in matrix to apply an erase pulse for stopping the discharge.

The gray scale information required for image display is implemented by giving different lengths of time for discharging individual cells within a given time necessary to display the entire image, for example, 1/30 second in the case of an NTSC TV signal. In this case, the brightness of the screen is determined by the brightness when each cell is driven to the maximum, and in order to increase the brightness, the discharge time of the cell can be kept as long as possible within a given time for composing a screen. The drive circuit must be designed.

As an example of the driving method of the plasma display panel according to Japanese Patent Laid-Open No. 7-160218, as shown in FIG. 3, the first row electrodes X are connected in common, and all the first row electrodes X are connected. The same voltage is applied. Meanwhile, the second row electrode Y and the column electrode W may apply separate voltages to each line. The voltage waveforms shown in FIG. 3 are voltage waveforms applied to the column electrodes Wj, the first row electrodes X, and the second row electrodes Y1, Y2, Yn sequentially from the top.

First, in FIG. 3, the reset period is a period in which all the cells of the AC plasma display are in the same state, and the front reset is performed on the first row electrode X commonly connected to all the screens at the initial point a of the reset period. A pulse Pp is applied. Since the front reset pulse Pp is set to be equal to or higher than the discharge start voltage between the first row electrode X and the second row electrode Y, regardless of whether the previous subfield is emitting or not emitting light, All cells discharge discharge light. At this time, although a voltage pulse is applied to the column electrode W, the potential difference between the first row electrode X and the column electrode W is adjusted so that a discharge does not occur between the first row electrode X and the column electrode W. It is set to a value that is approximately 1/2 of the voltage between the first row electrode X and the second row electrode Y for the purpose of making it small.

When the front reset pulse Pp is applied, a strong discharge occurs between the first row electrode X and the second row electrode Y, and a large amount of wall charge is accumulated between the X-Y electrodes and the discharge ends.

Next, when the front reset pulse Pp gradually drops at the point b of FIG. 3 and there is no applied voltage to the first row electrode X and the second row electrode Y, the previous front reset pulse between the XY electrodes. The electric field due to the wall charge accumulated at (Pp) remains. Since this electric field is large and can start discharging again by itself, discharge occurs between the first row electrode X and the second row electrode Y again. However, since there is no externally applied voltage, electrons or ions due to discharge are neutralized and disappear without moving to the first and second row electrodes X and Y.

In this way, all cells are recorded and erased in the previous subfield regardless of the presence or absence of wall charges, and reset is performed in such a manner that the wall charges of the cells of the entire screen are removed. Even when there is no externally applied voltage, the discharge that is discharged only by the accumulated wall charges and the wall charges are erased is called self-erasing discharge.

At the point c during the completion of this reset period, almost no wall charges remain in the first row electrode X and the second row electrode Y. On the other hand, in the discharge cell, a small amount of charged particles generated by the discharge by the previous front reset pulse Pp remains. This charged particle serves to make the discharge in the next recording more sure, and serves as a seed (seeding) of the recording discharge, and combines the seeding effect and the erasing effect with one pulse.

The address period in Fig. 3 is a period in which any cell on the screen controls the presence or absence of wall charges in each cell by matrix selection of the row electrode and the column electrode. The above writing is also performed in this address period.

In the address period, negative scan pulses Scp are sequentially applied to the independent second row electrodes Y1 to Yn to perform scanning. On the other hand, the positive address pulse Ap is applied to the column electrode W in response to the contents of the image data. An arbitrary cell can be selected by the scan pulse Scp applied to the second row electrode Y and the address pulse Ap applied to the column electrode W.

Since the total voltage value of the scan pulse Scp and the address pulse Ap is set to be equal to or higher than the discharge start voltage between the second row electrode Y and the column electrode W of the cell, the scan pulse Scp and the address pulse ( In the cells to which Ap) is simultaneously applied, discharge occurs between the YW electrodes. In addition, the common first row electrode X is held at the positive voltage value during the address period. Although the voltage value does not discharge between the first row electrode X and the second row electrode Y even if the voltage value of the scan pulse Scp is summed, it is discharged between the second row electrode Y and the column electrode W. When this occurs, the discharge is triggered, and at the same time, the discharge is set between the first row electrode X and the second row electrode Y at a voltage value at which the discharge is likely to occur.

The discharge between the first row electrode X and the second row electrode Y caused by triggering the discharge between the second row electrode Y and the column electrode W is also referred to as a write sustain discharge. By this write sustain discharge, wall charges are accumulated on the first and second row electrodes.

After the scanning of the entire screen, the sustain discharge period is completed. In this sustain discharge period, only the cells with wall charges sustain sustain after the address period.

Light emission by the sustain discharge is used for display, so that only cells with a long time of light emission by the sustain discharge within one frame glow brightly.

In the PDP, gray scale display can be performed by controlling the light emission time for each cell.

When the sustain discharge period is reached, sustain pulses are simultaneously applied to cells of all screens at point d of FIG. 3, and sustain pulses Scp are applied at point e of FIG. 3 only to cells that are addressed in the address period and accumulate wall charges. Cells that discharge and do not form wall charges do not sustain sustain discharge. Then, during the reset period of the next subfield, the front reset pulse Pp is applied to all cells to perform the reset.

4 shows the configuration of a conventional PLE circuit and is disclosed in EP99101977.9 and Japanese Patent Laid-Open No. 2002-33780. The RGB data is analyzed in an average power measurement block 416, which provides the calculated average luminance level (ASP) for the input image to the Peak White Enhancement Factor (PWEF) control block 414. do. The PWEF control block 417 generates the selected mode control signal with reference to the previously measured average brightness level and its internal power level mode table.

The PWEF control block 417 selects a pre-scailing factor (PS) and a subfield coding parameter (CD) to be used. PS is for changing the level of the input image, CD is for adjusting the configuration of the sub-field and the number of sustain pulses. That is, the CD is, for example, the number of subfields, the position of the subfield, the weight of the subfield, and the types of the subfield.

The PWEF control block 417 also includes a serial-to-parallel conversion circuit for writing RGB pixel data (WR) to the frame memory 412, reading RGB subfield data from the frame memory 414 (RD), and addressing lines. To control (SP). Finally, the PWEF control block 417 generates the scan pulses and the sustain pulses required to drive the PDP panel 415.

In the apparatus shown in FIG. 4, when the average luminance level of the input image increases, a mode having a decreasing power level is selected. When the average brightness level decreases, the mode with increasing power level is selected. For example, when a low average luminance level image is input, more sustain pulses are formed.

FIG. 5 is disclosed in Japanese Patent Application Laid-Open No. 2000-8125 as an example of a table showing the configuration of subfields and the number of sustain pulses according to the average luminance level of an input image.

As shown in FIG. 5, the average luminance level of the input image is classified into one of eight types, and different subfield configurations and the number of sustain pulses correspond to each classification.

Determining the maximum number of sustain discharge pulses per frame according to the average brightness level of the input image is determined as follows. First, the power luminance characteristic of the PDP is measured.

6 is a graph showing the power characteristics of the PDP. The first consideration in measuring the power characteristics is to determine the number of maximum sustain discharge pulses (hereinafter referred to as the maximum number of sustain discharge pulses) Ns per frame. The power consumption according to the change of the load ratio (L) is measured while changing the maximum number of sustain discharge pulses Ns. At this time, since the number of cases of the load factor L is large, about 10 are taken.

The load factor L is equal to an average luminance level (ASL), and is determined as in Equation 1 below.

Here, R / G / B represents red, green, and blue components of an image signal, respectively, and a / b / c represents a weight of R / G / B, that is, when a luminance signal is obtained by combining R / G / B. The proportion of each component is shown and depends on the gamma properties of the PDP. Also, Represents the sum within the frame, and N_px to represents the number of pixels of the PDP panel.

Next, as shown in FIG. 6, the luminance characteristic curve is obtained by referring to the power characteristic curve obtained through the measurement.

First, with reference to the graph shown in FIG. 6, the threshold value Lth of the load factor L which starts power control from the power curve at Ns = Nmax is calculated | required.

Next, when the load ratio L is 100%, the number Nmin of sustain discharge pulses per frame for determining the maximum luminance is determined.

Since the power consumption is linearly proportional to the average brightness level, the power P can be approximated as a linear function of the load factor L as shown in Equation 2 below.

P = P_o + alpha L = f (N_s, L)

Here, P_0 represents power consumption when the load factor L is 0%.

If P_d ~ is a power characteristic curve designed within the range of L_th ~ = ~ L ~ <= ~ 100% ~, P = f (N_s, L obtained as an approximation from the measurement result as shown in P_d ~ and Equation 2 The Ns value obtained at the intersection point of) becomes the number Ns of the maximum sustain discharge pulses at each load ratio L. This result is shown in FIG.

7 shows the luminance characteristic curve in the PDP. In the luminance characteristic curve shown in Fig. 7, the curve represents the designed power characteristic curve P_d ~, and the point on the curve represents the maximum number Ns of sustain discharge pulses per frame relative to the load factor L.

Ns is obtained by the intersection of the designed power characteristic curve P_d ~ and P = f (N_s, L) obtained from the measurement result as an approximation. In addition, between the power consumption at the critical load ratio Lth and the power consumption at the maximum load ratio becomes a safety operation area of the power control.

8 is a table showing the number of sustain pulses according to the average brightness level. The average brightness level is non discrete but quantized to discrete values for ease of control. For example, the average brightness level is quantized to one of 126 steps.

The number Ns of sustain pulses corresponds to each average luminance level. For example, Ns_126 corresponds to the ASL of the 126th step, and Ns_125 corresponds to the ASL of the 125th step.

If a similar image persists in human visual characteristics, it may be found that a change in luminance is not easily recognized even if the luminance of the image is gradually decreased. By using this, the brightness is gradually lowered while a similar image is sustained, resulting in a power saving effect.

On the other hand, when the input image is changed from a low average brightness level to a high average brightness level, even if the display is slightly lower than the high average brightness level, there is a characteristic that it is not easily recognized. In this case, when the input image is changed from a low average luminance level to a high average luminance level, the display may be displayed at a level slightly lower than the high average luminance level, thereby reducing power consumption.

The power control method of the present invention efficiently reduces power consumption by gradually lowering the luminance displayed on the PDP when an image having the same average luminance level of the input image is input for a predetermined time by using the human visual characteristic. It features.

9 are power control curves for schematically showing a power control method according to the present invention.

Referring to FIG. 9, there are two power control curves P1 and P2, and there is an upper limit and a lower limit defined by each power control curve for a certain load factor. While the average brightness level of the input image remains the same, power consumption is gradually reduced from the upper limit to the lower limit of FIG. Reducing power consumption is achieved by reducing the maximum number of sustain pulses per frame.

10 schematically shows a power control method according to the present invention.

The average brightness level is quantized to one of 126 steps. The number Ns of sustain pulses corresponds to each average luminance level. Note that there are several numbers of corresponding sustain pulses for a certain step of the average luminance level. The reason why the number of sustain pulses corresponding to a certain step of the average brightness level is different is to allow to reduce power consumption by gradually lowering the number of sustain pulses while the average brightness level of the input image is maintained for a predetermined time. will be.

The corresponding number of sustain pulses has a range for a certain step of average luminance level, which range is variable for each step.

For example, referring to FIG. 10, Ns_126-Ns_120 correspond to the ASL of the 126th step, and Ns_124-Ns_118 correspond to the ASL of the 124th step.

11 is a flowchart showing a preferred embodiment of the power control method according to the present invention.

First, in order to measure an average luminance level of an input image, an accumulated value of an RGB signal per frame is obtained (s1102).

The average luminance level of the input image is measured and the range of the power consumption mode APC suitable for the measured average luminance level ASL is obtained. (S1104) The average luminance level is measured as shown in Equation 1, and the measurement period is one frame period. to be. This measurement period corresponds to a predetermined second period in the summary of the present invention.

A range of APCs corresponds to the measured ASL as shown in FIG. 8, and these are stored in the lookup table (s2204). Here, the value of the APC is a parameter that specifically determines the number Ns of sustain pulses. to be.

As a result of the s1104 process, the upper boundary and the lower boundary of the APC are obtained for the measured ASL.

It is determined whether the upper boundary read in step s1104 is smaller than Formal_APC (s806). Here, Formal_APC is the previous APC, and this value is updated with a hold time period.

If the upper boundary read in step s804 in step s1106 is not smaller than Formal_APC, step S1108 is performed by determining the upper side, otherwise step S1110 is determined by the lower side.

12 schematically shows the relationship between the average luminance level ASL and the APC range.

Referring to FIG. 12, APC ranges for two ASLs (ASL1, ASL2, ASL3) are shown. In Fig. 12, the vertical axis represents APC and the lower the power consumption is, the larger the value of APC is. 11, ASL1, ASL2, and ASL3 correspond to the cases where the load ratio L is 100%, 15%, and 50%, respectively.

Power control for ASL3, which is the average luminance level of the previous input image, is performed between the upper limit 3 and the lower limit 3. If the average luminance level of the input image continues to maintain ASL3, the value of APC continues to increase until the lower limit 3 is reached between the upper limit 3 and up.

In step s1108, if Current_ASL is greater than Formal_ASL, Current_APC is updated to the upper limit. This sets the current power control mode to the upper limit when the average luminance level of the currently input image is greater than the average luminance level of the previously input image. Here, the upper limit is a power control mode with less power consumption than the lower limit. That is, if the average brightness level of the input image is increased, the displayed image is brighter than the previously displayed image, but is set to a lower power control mode in consideration of power consumption.

If Current_ASL is not greater than Formal_ASL, update Current_APC to the lower limit. This sets the current power control mode to the lower limit if the average luminance level of the currently input image is lower than the average luminance level of the previously input image. Here, the lower limit is the power control mode with high power consumption. That is, if the average luminance level of the input image is reduced, the displayed image is set to a higher power control mode as the displayed image becomes brighter than the previously displayed image. After the process of s1108 ends, the process proceeds to s1112.

In step s1110, if Current_ASL is greater than Formal_ASL, Current_APC is updated to the upper limit. On the other hand, if Current_ASL is not greater than Formal_ASL, Current_APC is updated to the lower limit. After the process of S1110 ends, the process proceeds to S1112.

In operation s1112, when an image having the same average luminance level is continuously input for a predetermined time (hold time), the process performs a function of gradually decreasing luminance within a range. Specifically, the average luminance level is compared in the hold time period, and if the previous average luminance level and the current average luminance level are the same, the value of the APC is adjusted so as to reduce power consumption within the APC range corresponding to the average luminance level. Here, the hold time corresponds to a predetermined first period in the summary of the present invention.

First, if the lower limit is equal to Formal_APC, then Update Current_APC to the lower limit. In other words, if the ASL reaches the lowest value within a given limit, it does not deteriorate further. On the other hand, if the lower limit is larger than Formal_APC, the value of Current_APC is increased by one. That is, the power consumption is slightly reduced.

In step s1114, the APC value is passed for other processing. The number of sustain pulses is determined by the APC delivered.

As described with reference to the flowchart of FIG. 11, in the power control method according to the present invention, if the average luminance level of the input image is kept constant for a predetermined time, the luminance of the displayed image is lowered, that is, the number of sustain pulses is reduced. By effectively reducing power consumption.

13 is a block diagram showing the configuration of a preferred embodiment of the device to which the power control method according to the present invention is applied. In the apparatus shown in FIG. 13, the RGB accumulator 1302 receives an input image signal, and accumulates an R / G / B accumulated value per frame, that is, the molecule of Equation 1 To calculate. To this end, the APC_RGB_SUM block 1302 includes an accumulator.

The ASL calculator 1302 is provided by the RGB accumulator 1302. And R / G / B weights (a, b, c) and the number of pixels (Npx) of the PDP panel are introduced, and the average luminance level ASL is obtained using the equation shown in Equation (1). To this end, the ASL calculator 1302 includes a multiplier and a divider.

The APC determiner 1306 refers to the lookup table 1308 to obtain a range of APCs corresponding to the average luminance level ASL obtained by the APC calculator 1304. In addition, the previous ASL is compared with the current ASL in a hold time period, and the value of the APC is determined according to the comparison result. Hold time is calculated by a timer (not shown). The lookup table 1308 stores a range of APCs corresponding to, for example, the average luminance level ASL as shown in FIG. 10. Lookup table 1308 is implemented with conventional memory.

Specifically, the values of APC are determined by performing processes S1106 to S1112 of the flowchart shown in FIG. 11.

In other words, if Current_ASL is not greater than Formal_ASL, Current_APC is updated to the lower limit. If Current_ASL is greater than Formal_ASL, Current_APC is updated to upper limit. In addition, if Current_ASL is equal to Formal_ASL, the power consumption is reduced by increasing the APC value by one step within the given range.

The APC output from the APC decision unit 1306 is provided to a block (not shown) that generates a sustain pulse to control the maximum number of sustain pulses per frame.

The method of the present invention may be implemented by an apparatus as shown in FIG. 13 but may also be implemented by a computer program or code segments. In this case, even if the method of calculating the average luminance level is changed or there is a change in the program for determining the APC, the hardware can easily cope with this, thereby securing flexibility in the hardware configuration of the PDP driving apparatus.

The program or code segments may be stored in a processor readable medium or transmitted by a computer data signal coupled with a carrier on a transmission medium or network. Processor readable media includes any medium that can store or transmit information. Examples of processor-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memory, erasable ROM (EROM), floppy disks, optical disks, hard disks, optical fiber media, radio frequency (RF) networks, and the like. There is this. Computer data signals include any signal that can propagate over transmission media such as electronic network channels, optical fibers, air, electromagnetic fields, RF networks, and the like.

Specific embodiments shown and described in the accompanying drawings are only to be understood as an example of the present invention, not to limit the scope of the invention, but also within the scope of the technical spirit described in the present invention in the technical field to which the present invention belongs As various other changes may occur, it is obvious that the invention is not limited to the specific constructions and arrangements shown or described.

As described above, in the power control method according to the present invention, if the average luminance level of the input image remains constant for a predetermined time, the power consumption of the PDP is effectively reduced by lowering the luminance of the displayed image, that is, lowering the number of sustain pulses. Will reduce the cost.

1 shows a configuration of a general surface discharge type AC PDP.

2 shows the configuration of a subframe in a surface discharge type plasma display panel.

FIG. 3 is a voltage waveform diagram in a first subfield showing a method of driving the surface discharge type plasma display panel of FIG. 2.

4 shows the configuration of a conventional PLE circuit.

FIG. 5 is disclosed in Japanese Patent Application Laid-Open No. 2000-8125 as an example of a table showing the configuration of subfields and the number of sustain pulses according to the average luminance level of an input image.

6 is a graph showing the power characteristics of the PDP.

7 shows the luminance characteristic curve in the PDP.

8 is a table showing the number of sustain pulses according to the average brightness level.

9 are power control curves for schematically showing a power control method according to the present invention.

10 schematically shows a power control method according to the present invention.

11 is a flowchart showing a preferred embodiment of the power control method according to the present invention.

12 schematically shows the relationship between the average luminance level ASL and the APC range.

13 is a block diagram showing the configuration of a preferred embodiment of the device to which the power control method according to the present invention is applied.

Claims (8)

A method of measuring an average brightness level of an input signal in units of frames, setting a power control level corresponding to the measured average brightness level among a plurality of power control levels, and displaying an input image on the PDP according to the set power control level. In Setting a power control level for each of the discrete average brightness levels each having a predetermined power control range; Comparing the average brightness levels in a first predetermined period, and if the current average brightness level is equal to the previous average brightness level, controlling the power consumption to gradually decrease within a power control range corresponding to the set power control level; And Compare average luminance levels with a second period that is less than or equal to the first period, and when the current average luminance level is different from the previous average luminance level, the power corresponding to the current average luminance level among the plurality of power control levels. If the current average brightness level is greater than the previous average brightness level, the control level is set so that the lower power consumption is within the range of the corresponding power control level. The power control method of the PDP comprising the step of setting the power consumption as high as possible. delete delete delete delete An apparatus for measuring an average brightness level of an input signal in an average frame unit, setting a power control level corresponding to the measured average brightness level among a plurality of power control levels, and displaying an input image on the PDP according to the set power control level. To An ASL calculator configured to measure an average luminance level ASL of the input signal; A memory for storing a lookup table corresponding to each of the discrete average luminance levels, the power control level each having a predetermined power control range; And An APC controller configured to adjust the power control level of the PDP by referring to the average luminance level measured by the ASL calculator and a lookup table stored in the memory; Here, the APC control unit Comparing the average brightness levels in a first predetermined period, and when the current average brightness level is the same as the previous average brightness level, controlling the power consumption to be gradually lowered within a power control range corresponding to the set power control level, Compare average luminance levels with a second period that is less than or equal to the first period, and when the current average luminance level is different from the previous average luminance level, the power corresponding to the current average luminance level among the plurality of power control levels. If the current average brightness level is greater than the previous average brightness level, the control level is set so that the lower power consumption is within the range of the corresponding power control level. The power control device of the PDP, characterized in that the higher power consumption is set to be. delete delete