JP2008310148A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably eliminate luminance irregularity caused by fluctuation or changes with lapse of time of a side light type backlight. <P>SOLUTION: When the luminance of a liquid crystal panel changes before or after an increase in the transmittance for light in a liquid crystal panel and a decrease in the luminous energy of light exiting from a backlight, a luminance difference eliminating section 71 determines a modulation amount f and a control amount g for eliminating the luminance difference. A backlight control section 8 subtracts the control amount g from the luminous energy of light exiting from an LED in the backlight in the latest frame period and causes the LED to emit light in the subtracted luminous energy. Each modulation circuit 3 adds the modulation amount f to each grayscale value used to display an image in the latest frame period. Thus, an image with the grayscale value after addition is displayed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device in which luminance unevenness caused by variations in backlight and changes with time is surely eliminated.

  Conventionally, many active matrix liquid crystal display devices include a backlight. In recent years, instead of a backlight using a cold cathode tube, a backlight in which LEDs are arranged on the side surface of a light guide plate, a so-called sidelight type backlight is used.

  Regardless of the type of backlight, in a liquid crystal display device, when displaying a black image, power consumption can be reduced by modulating the image to the white side and reducing the amount of light from the backlight.

  As shown in FIG. 5, for example, when an image having a white spot on a black background is displayed on the liquid crystal panel 12 using a sidelight type backlight, the amount of light of each LED is uniformly reduced, and the image is displayed on the white side. Modulate to At this time, the brightness of the white spot may be insufficient. However, if the amount of light of the LED 9 that emits light reaching the white spot is increased, the brightness of the overlapping area between the area where the light of the LED 9 reaches and the black background increases. As a result, luminance unevenness occurs.

  Accordingly, the luminance unevenness is eliminated by increasing the amount of light of the LED 9 and reducing the modulation to the white side in a portion where the area where the light of the LED 9 reaches and the black background overlap.

In order to perform such control, a relative positional relationship between the position of one LED and the area where the light reaches may be obtained in advance and stored in a graphic chip or the like. In this way, the above-described control can be performed based on the stored contents.
JP 2005-258403 A

  However, the light guide plate has a variation in light guide performance, and the LED has a range of light and a variation in light quantity and a change in diameter. In some cases, the luminance unevenness cannot be eliminated by the method of storing.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display device that is intended to reliably eliminate luminance unevenness caused by variations in backlight and changes with time. There is to do.

  In order to solve the above-described problems, a liquid crystal display device according to a first aspect of the present invention includes a liquid crystal panel, a backlight positioned on the back of the liquid crystal panel, and the liquid crystal so that the luminance of the liquid crystal panel does not change. Based on the measured luminance information, the control unit that increases the light transmittance of the panel and decreases the amount of light emitted from the backlight, the luminance measurement circuit that measures the luminance of the liquid crystal panel, and the backlight A luminance difference elimination unit that changes at least one of the light transmittance and the light amount so as to eliminate the luminance difference caused by the light is provided.

  In the first aspect of the present invention, by providing a luminance difference elimination unit that changes at least one of the transmittance and the light amount so as to eliminate the difference in luminance, at least one of the transmittance and the light amount is changed, A difference in luminance can be eliminated, and therefore luminance unevenness due to variations in backlight and changes with time can be surely eliminated.

  The liquid crystal display device according to the second aspect of the present invention increases the light transmittance of the liquid crystal panel so that the liquid crystal panel, the backlight positioned on the back of the liquid crystal panel, and the luminance of the liquid crystal panel do not change. And a controller for reducing the amount of light emitted from the backlight, a luminance measuring circuit for measuring the luminance of the liquid crystal panel, and before and after the increase in light transmittance and the decrease in the amount of light by the control of the controller. A luminance difference elimination unit that changes at least one of the light transmittance and the light amount so as to eliminate the difference in measured luminance is provided.

  In the second aspect of the present invention, there is provided a luminance difference elimination unit that changes at least one of the transmittance and the light amount so that the difference in luminance measured before and after the increase of the light transmittance and the decrease of the light amount is eliminated. As a result, at least one of the transmittance and the amount of light can be changed to eliminate the difference in luminance, and thus the luminance unevenness caused by the variation in the backlight and the change with time can be surely eliminated.

  The liquid crystal display device according to the third aspect of the present invention increases the light transmittance of the liquid crystal panel so that the liquid crystal panel, the backlight located on the back of the liquid crystal panel, and the luminance of the liquid crystal panel do not change. And a controller for reducing the amount of light emitted from the backlight, a luminance measuring circuit for measuring the luminance of the liquid crystal panel, and a luminance measured when a predetermined image is displayed on the liquid crystal panel. A luminance difference elimination unit that changes at least one of the light transmittance and the light amount so as to eliminate a difference from a predetermined luminance is provided.

  According to the third aspect of the present invention, at least one of the light transmittance and the light quantity is eliminated so that the difference between the luminance measured when the predetermined image is displayed and the predetermined luminance is eliminated. By providing at least one of the transmittance and the amount of light, the difference in luminance can be eliminated by changing the luminance difference canceling section that changes the brightness of the backlight. It can be surely solved.

  According to the present invention, it is possible to eliminate a difference in luminance by changing at least one of the transmittance and the amount of light, and thus it is possible to reliably eliminate luminance unevenness due to variations in backlight and changes in diameter. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a plan view and a block diagram of a liquid crystal display device according to an embodiment of the present invention.

  The liquid crystal display device includes a liquid crystal panel including a liquid crystal layer, an array substrate, and a counter substrate (both not shown). The liquid crystal layer is disposed between the array substrate and the counter substrate.

  In the array substrate, a plurality of signal lines X and a plurality of scanning lines Y are formed and cross each other. A pixel E is arranged at each intersection of the signal line X and the scanning line Y. In each pixel E, a thin film transistor Q, a pixel electrode P, and a photosensor S are formed. The optical sensor S is connected to the signal line X and the scanning line Y.

  The liquid crystal display device includes one shift register 1, a latch circuit 2 for each signal line X, a modulation circuit 3 for each signal line X, a digital-analog conversion circuit (hereinafter referred to as “DA conversion circuit”) 4 for each signal line X, A switching element 5 for each signal line X, an analog-digital conversion circuit (hereinafter referred to as “AD conversion circuit”) 6 for each signal line X, a set of amplifiers (amplifiers) for each signal line X, a control unit 7 and backlight control Part 8 is provided. The amplifier set a includes an amplifier a1 and an amplifier a2.

  Although not shown, a sidelight type backlight (hereinafter simply referred to as “backlight”) is provided on the back surface of the array substrate. The backlight control unit 8 controls the amount of light emitted from the backlight.

  The controller 7 increases the light transmittance of the liquid crystal panel and decreases the amount of light emitted from the backlight so that the luminance of the liquid crystal panel does not change.

  The optical sensor S measures the luminance of the liquid crystal panel and corresponds to a luminance measuring circuit.

  If there is a difference between the luminance measured before and after the increase in the light transmittance and the decrease in the light amount, the control unit 7 changes the luminance difference to further change the light transmittance and the light amount so as to eliminate the difference. A cancellation unit 71 is provided.

  The luminance difference canceling unit 71 further changes the light transmittance and the light amount so that the difference is eliminated when the luminance difference caused by the variation of the backlight or the change with time occurs in the measured luminance. is there.

  The output of the shift register 1 to which the digital image data is supplied is supplied to the latch circuit 2 so as to correspond to each signal line X, and the output of the latch circuit 2 is supplied to the modulation circuit 3. When a modulation signal from the luminance difference canceling unit 71 described later does not arrive, no modulation operation is performed. The output of the modulation circuit 3 is converted into analog data by the DA conversion circuit 4, and the output of the DA conversion circuit 4 is supplied to the terminal 51 of the switch element 5 via the amplifier a1.

  In the liquid crystal display device, the switching terminal 52 of the switch element 5 is connected to the signal line X, and the terminal 53 of the switch element 5 is connected to the AD conversion circuit 6 via the amplifier a2. The switching element 5 is controlled so that the switching terminal 52 is switched and connected to the terminal 51 during the scanning period (writing period), and the switching terminal 52 is switched and connected to the terminal 53 only during the horizontal blanking period H. . In other words, the output of the optical sensor S is supplied to the AD conversion circuit 6 via the switch element 5 only during the horizontal blanking period H. Further, the output of the AD conversion circuit 6 is supplied to the control unit 7, and the output of the control unit 7 is supplied to the modulation circuit 3 and the backlight control unit 8.

  As shown in FIG. 2, the control unit 7 stores the position of the display area 10 of the liquid crystal panel corresponding to each light emitting diode (hereinafter referred to as “LED”) 9 provided as a light source in the backlight in a reference table or the like. ing.

  Based on the gradation value used to display the image displayed on the liquid crystal panel, the control unit 7 obtains the display area 10 set to a value less than the maximum value of the light transmittance, and refers to it. The transmittance of light and luminance correction data based on the gradation values stored in the table increase the light transmittance in the display area 10 and the light emitted from the LED 9 corresponding to the display area 10 in the backlight. The amount of light is reduced.

  In order to perform such control, the control unit 7 stores the pitch 11 of the display area 10.

  In addition, the control unit 7 corresponds to a function (referred to as “function F”) for obtaining a modulation amount for increasing the light transmittance in the display area 10 ′, which is one of the display areas 10, and the display area 10 ′. A function (referred to as “function G”) for obtaining a control amount for reducing the amount of light emitted from the LED 9 is stored.

  The modulation amount is a value added to the gradation value used for displaying the image displayed on the liquid crystal panel.

  The control amount is a value that is subtracted from the amount of light emitted from the LED 9.

  In both the functions F and G, the arguments are pixels corresponding to the highest gradation value Gmax, the lowest gradation value Gmin, and the highest gradation value Gmax among the gradation values used to display the currently displayed image. This is the pitch Δ between the display area 10 ″ including Emax and the display area 10 ′. FIG. 2 illustrates the pixel Emin and the pixel Emin corresponding to the lowest gradation value Gmin.

  The liquid crystal display device performs control with a logic such that when the gradation value is increased, the light transmittance is increased in the pixel corresponding to the gradation value. Note that control may be performed with a logic opposite to this logic.

  The control unit 7 has a function (referred to as “function f”) for obtaining a modulation amount for increasing or decreasing the light transmittance in the display region 10 ′, and the amount of light emitted from the LED 9 corresponding to the display region 10 ′. Is stored as a function (referred to as “function g”) that provides a control amount for increasing or decreasing.

  This modulation amount is a value added to the gradation value used for displaying the image displayed on the liquid crystal panel. Note that this modulation amount may be a negative value, in which case it is a value that is substantially subtracted from the gradation value.

  The control amount is a value that is subtracted from the amount of light emitted from the LED 9. Note that this control amount may be a negative value, in which case it is a value that is substantially added to the amount of light.

  For both functions f and g, the argument is a correction amount k, and a modulation amount and a control amount corresponding to the correction amount k can be obtained by the functions f and g.

(Operation of the first embodiment)
Next, the operation of the liquid crystal display device will be described.

  Here, it is assumed that the liquid crystal display device displays an image corresponding to a signal from the outside, for example.

  First, an operation in a certain horizontal blanking period (hereinafter referred to as “horizontal blanking period H1”) will be described.

  As shown in FIG. 3, the luminance varies depending on the position of the pixel E, and the photosensor S in the pixel E at each position measures the luminance at the position of the pixel E. The analog voltage corresponding to the luminance is notified to the control unit 7 as a digital signal through the switch element 5, the amplifier a 2, and the AD conversion circuit 6 to which the switching terminal 52 and the terminal 53 are connected. The control unit 7 stores this luminance information.

  The control unit 7 determines the highest gradation among the gradation values used for displaying the image displayed in the frame (display) period immediately before the horizontal blanking period H1 (hereinafter referred to as “frame period F1”). A value Gmax and a minimum gradation value Gmin are obtained. Since each of these gradation values is stored in, for example, a memory having a reference table (not shown), the control unit 7 searches the memory for the highest gradation value Gmax and the lowest gradation value Gmin. Note that the control unit 7 does not obtain the highest gradation value Gmax and the lowest gradation value Gmin again unless a new gradation value is stored in the memory.

  The control unit 7 performs processing for each display region 10 in parallel. Since the principle of each process is the same, the process for the display area 10 ′ that is one of the display areas 10 will be described, and the description for the other display areas 10 will be omitted.

  The control unit 7 obtains a pitch Δ between the display area 10 ″ including the pixel corresponding to the highest gradation value Gmax and the display area 10 ′.

  The control unit 7 inputs the maximum gradation value Gmax, the minimum gradation value Gmin, and the pitch Δ into the function F, and obtains a modulation amount (referred to as modulation amount F).

  The control unit 7 inputs the highest gradation value Gmax, the lowest gradation value Gmin, and the pitch Δ into the function G, and obtains a control amount (referred to as a control amount G).

  The control unit 7 transmits the modulation amount F to each modulation circuit 3 corresponding to the display region 10 ′, changes the gradation value of the digital image data passing through the modulation circuit 3, and controls the control amount G and the display region 10 ′. The position is transmitted to the backlight control unit 8. The backlight control unit 8 subtracts the control amount G from the amount of light emitted from the LED 9 corresponding to the display area 10 ′ in the frame period F <b> 1.

  Next, a frame (display) period (hereinafter referred to as “frame period F2”) following the horizontal blanking period H1 will be described.

  In the frame period F2, each modulation circuit 3 adds the modulation amount F to each gradation value used for displaying an image displayed in the display area 10 '. In the display area 10 ′, an image with the added gradation value is displayed.

  Specifically, first, the DA conversion circuit 4 converts the gradation value after the addition into an analog video signal. The video signal is applied to the pixel electrode P through the amplifier a1, the switch element 5 in which the terminal 51 and the switching terminal 52 are connected, the signal line X, and the thin film transistor Q that is turned on. On the other hand, a predetermined voltage is also applied to the counter electrode provided on the counter substrate. Thereby, the light transmittance in the liquid crystal is in accordance with the gradation value. Of the light emitted from the backlight, only the amount corresponding to this transmittance is emitted from the front surface of the liquid crystal panel. In the frame period F2, the amount of light emitted from the backlight decreases.

  That is, in the frame period F2, the backlight control unit 8 emits the subtracted amount of light from the LED 9 corresponding to the display area 10 '.

  As shown in FIG. 4, when a certain gradation value is modulated (added), the light transmittance increases in the liquid crystal at the pixel position corresponding to the gradation value. Unless the amount of light emitted from the LED 9 is reduced, the luminance at that position increases. However, in practice, the luminance is maintained because the amount of light emitted from the LED 9 is reduced. Moreover, since the light quantity of the light radiate | emitted from LED9 is reduced, power consumption can be reduced.

  By the way, for a pixel or the like corresponding to the maximum gradation value Gmax, the gradation value may correspond to or be close to the maximum value of the light transmittance. There are cases where it can be increased only slightly.

  Accordingly, the functions F and G store in advance the gradation value GM corresponding to the maximum value of the light transmittance, and compare the gradation value GM with the maximum gradation value Gmax, or whether the pitch Δ is 0 or not. Based on whether or not the display area 10 ′ is a display area set to a transmittance less than the maximum value, and if the display area 10 ′ is such a display area, Since there is room for increasing the transmittance, values other than 0 are set for the modulation amount F and the control amount G.

  On the contrary, the functions F and G have no room for increasing the light transmittance if the display region 10 ′ is a display region set to the maximum value of the light transmittance. A value of 0 is set for the control amount G.

  In addition, the functions F and G obtain the magnitudes of the modulation amount F and the control amount G based on the maximum gradation value Gmax, the minimum gradation value Gmin, and the pitch Δ. That is, the functions F and G are adjusted such that the modulation amount F and the control amount G increase as the difference between the maximum gradation value Gmax and the minimum gradation value Gmin increases. The functions F and G are adjusted so that the modulation amount F and the control amount G increase as the pitch Δ increases.

  Next, a horizontal blanking period (referred to as “horizontal blanking period H2”) following the frame period F2 will be described.

  The photosensor S in each pixel E measures the luminance at the position of the pixel E. The analog voltage corresponding to the luminance is notified to the control unit 7 as a digital signal via the switch element 5, the amplifier a2, and the AD conversion circuit 6.

  The control unit 7 performs processing for each display region 10 in parallel. Since the principle of each process is the same, the process for the display area 10 ′, which is one of the display areas 10, will be described, and the description for the other display areas 10 will be omitted.

  The control unit 7 measures each luminance information measured and stored by the optical sensor S in the display area 10 ′ in the horizontal blanking period H1, and measured by the optical sensor S in the display area 10 ′ in the horizontal blanking period H2. The presence / absence of change as a whole is detected for each luminance information.

  For example, the control unit 7 calculates an average AV0 of each luminance measured in the horizontal blanking period H1 and an average AV1 of each luminance measured in the horizontal blanking period H2, and calculates difference = AV0−AV1.

  That is, the control unit 7 calculates the difference between the luminances measured before and after the increase in the light transmittance of the liquid crystal panel and the decrease in the amount of light emitted from the backlight.

  The functions F and G are adjusted so that the difference = 0 if the backlight does not vary or change with time. In other words, the functions F and G change the brightness of the liquid crystal panel before and after the increase in the light transmittance of the liquid crystal panel and the decrease in the amount of light emitted from the backlight if the backlight does not vary or change with time. It has been adjusted not to.

  Therefore, if the difference <0 or the difference> 0, the light amount of the light emitted from the backlight is decreased or increased compared to the ideal light amount due to variations and changes with time. In this case, for example, a certain display area 10 becomes darker or brighter than the other display areas 10. That is, luminance unevenness occurs.

  Therefore, for example, if the difference <0 or difference> 0, the luminance difference canceling unit 71 of the control unit 7 sets the correction amount k to a value according to the difference, and inputs the correction amount k to the function f. A modulation amount (referred to as modulation amount f) is obtained.

  Similarly, if the difference <0 or difference> 0, the luminance difference canceling unit 71 sets the correction amount k to a value corresponding to the difference, inputs the correction amount k to the function g, and sets the control amount (referred to as the control amount g). )

  The luminance difference canceling unit 71 transmits the modulation amount f to each modulation circuit 3 corresponding to the display region 10 ′, and transmits the control amount g and the position of the display region 10 ′ to the backlight control unit 8. The backlight control unit 8 subtracts the control amount g from the amount of light emitted from the LED 9 corresponding to the display area 10 ′ in the frame period F <b> 2. That is, the control amount g is further subtracted from the light amount after the control amount G is subtracted. The control amount g may be a negative value, and in this case, a light amount greater than the light amount in the frame period F2 is calculated.

  Next, a frame (display) period (referred to as “frame period F3”) following the horizontal blanking period H2 will be described.

  In the frame period F3, each modulation circuit 3 adds the modulation amount f to each gradation value used for displaying the image displayed in the display area 10 'in the frame period F2. That is, the modulation amount f is further added to the gradation value after the modulation amount F is added. The modulation amount f may be a negative value. In this case, a gradation value smaller than the gradation value in the frame period F2 is calculated. In the display area 10 ′, an image having a gradation value after adding the modulation amount f is displayed.

  Further, in the frame period F3, the backlight control unit 8 emits light having a light amount after subtracting the control amount g from the LED 9 corresponding to the display region 10 '.

  The functions f and g are adjusted so that the difference = AV0−AV1 = 0.

  In other words, if there is a difference between the luminances measured before and after the increase in the light transmittance of the liquid crystal panel and the decrease in the amount of light emitted from the backlight, the functions f and g are eliminated. It has been adjusted.

  Therefore, even when the amount of light emitted from the backlight is reduced or increased compared to the ideal amount of light due to variations or changes over time, the luminance of each display region 10 is subject to variations or changes over time. It can be the same as the brightness in the absence. Therefore, a certain display area 10 does not become darker or brighter than other display areas 10. That is, it is possible to prevent luminance unevenness from occurring.

  When a new gradation value is stored in the memory, the control unit 7 obtains the maximum gradation value Gmax and the minimum gradation value Gmin from the memory, and thereafter, in the liquid crystal display device, the same operation as that described above is performed. An action will be made.

  In the present embodiment, the average of the respective luminances is obtained when detecting whether or not each luminance of the display area 10 ′ has changed as a whole. For example, this may be replaced with an intermediate value of each luminance. Good.

  Further, in the present embodiment, the difference in the amount of light and the difference in luminance caused by variations and changes with time are eliminated by using the functions f and g. It is also possible to eliminate the difference in the light amount and the difference in luminance due to variations and changes with time by only modulating the light amount or controlling the light amount.

  Further, in this embodiment, the difference between the measured luminance before and after the increase in the light transmittance of the liquid crystal panel and the decrease in the amount of light emitted from the backlight is eliminated. May be.

  First, when a predetermined image (for example, an image of one white color) is displayed on the liquid crystal panel, the optical sensor S measures the luminance of the liquid crystal panel. Then, if there is a difference between the measured luminance and a predetermined luminance, the luminance difference elimination unit 71 eliminates the difference.

  The predetermined luminance is set to be equal to the measured luminance when the image is displayed and the amount of light emitted from the backlight is predetermined.

  Therefore, if there is a difference between the luminances, the light amount is decreased or increased with respect to the ideal light amount due to variations and changes over time. In addition, it is sufficient to eliminate the difference.

  In the above-described embodiment, the case where a sidelight-type backlight including LEDs is used has been described. However, a liquid crystal including a sidelight-type backlight in which a cold cathode tube is disposed opposite to a side surface of a light guide plate. The above-described operation may be performed in the display device.

  Further, the above-described operation may be performed in a liquid crystal display device including a direct type backlight including an LED and a cold cathode tube.

  In the above embodiment, the case where the photosensors S are provided in all the pixels E has been described. However, since there are a plurality of pixels E in the display area 10 that each LED 9 handles. The photosensor S can be arranged for each group unit in which a plurality of pixels E are grouped to simplify the configuration of the entire apparatus.

It is a figure which shows the top view and block diagram of a liquid crystal display device which concern on embodiment of this invention. It is a figure which shows each display area 10 and each LED9 which were comprised by the liquid crystal panel. 6 is a diagram illustrating a luminance distribution according to a position of a pixel E. FIG. It is a figure for demonstrating that a gradation value, the transmittance | permeability of light, a brightness | luminance, and a light quantity link. It is a figure for demonstrating control of the gradation and backlight in the conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shift register 2 Latch circuit 3 Modulation circuit 4 DA conversion circuit 5 Switch element 6 AD conversion circuit 7 Control part 71 Luminance difference cancellation part 8 Backlight control part E Pixel P Pixel electrode Q Thin film transistor S Photosensor X Signal line Y Scan line

Claims (4)

LCD panel,
A backlight located on the back of the liquid crystal panel;
A controller that increases the light transmittance of the liquid crystal panel and reduces the amount of light emitted from the backlight so that the brightness of the liquid crystal panel does not change;
A luminance measuring circuit for measuring the luminance of the liquid crystal panel;
A liquid crystal display comprising: a luminance difference eliminating unit that changes at least one of the light transmittance and the light amount so as to eliminate a difference in luminance caused by the backlight based on the measured luminance information. Display device. LCD panel,
A backlight located on the back of the liquid crystal panel;
A controller that increases the light transmittance of the liquid crystal panel and reduces the amount of light emitted from the backlight so that the luminance of the liquid crystal panel does not change;
A luminance measuring circuit for measuring the luminance of the liquid crystal panel;
A luminance difference eliminating unit that changes at least one of the light transmittance and the light amount so as to eliminate the difference in luminance measured before and after the increase in light transmittance and the decrease in the light amount under the control of the control unit; A liquid crystal display device comprising: LCD panel,
A backlight located on the back of the liquid crystal panel;
A controller that increases the light transmittance of the liquid crystal panel and reduces the amount of light emitted from the backlight so that the luminance of the liquid crystal panel does not change;
A luminance measuring circuit for measuring the luminance of the liquid crystal panel;
Luminance difference elimination that changes at least one of the light transmittance and the light amount so that the difference between the luminance measured when the predetermined image is displayed on the liquid crystal panel and the predetermined luminance is eliminated. And a liquid crystal display device. The controller is
Based on the gradation value used to display the image displayed on the liquid crystal panel, an area set to a value less than the maximum value of the light transmittance is obtained, and light transmission in the area is determined. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to increase a rate and reduce a light amount of light emitted from a light source corresponding to the region in the backlight.

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