KR20210136829A - Backlight driver, backlight device including the same and operationg method of the backlight device - Google Patents

Abstract

A backlight device in accordance with technical ideas of the present disclosure comprises: a backlight unit including multiple LED elements, the multiple LED elements divided into multiple dimming groups; a panel driver outputting a reference current to drive the multiple LED elements; and multiple pixel circuits connected to the panel driver through a common line and respectively, driving first LED elements included in a corresponding dimming group from among the multiple dimming groups. Each of the pixel circuits converts the reference current into a reference voltage and stores the same in a time-sharing method in a first period of a frame period, acquires luminance data of an image displayed by a corresponding dimming group from among the multiple dimming groups in a second period of the frame period, and drives the first LED elements using the stored reference voltage for a light emission time corresponding to the acquired luminance data in a third period of the frame period. In accordance with the present invention, the brightness uniformity is excellent by performing a local dimming operation based on the reference current.

Description

A backlight driver, a backlight device including the same, and a method of operation of the backlight device

The technical idea of the present disclosure relates to a backlight driver, a backlight device including the same, and a method of operating the backlight device, and more specifically, a backlight driver for driving LED elements using a plurality of pixel circuits sharing one current source, and the backlight driver including the same The present invention relates to a backlight device and a method of operating the backlight device.

A display device is widely used in a smart phone, a notebook computer, a monitor, and the like, and the display device may include a display panel for displaying an image. In this case, when the display panel is a liquid crystal display (LCD) panel rather than an organic light emitting diode (OLED) panel including a device that emits light by itself, a backlight device for improving a contrast ratio may be provided. The backlight device includes a plurality of light emitting diode (LED) devices, and may be disposed on the rear surface of the display panel.

Recently, a local dimming technique of driving a plurality of LED elements for each area of a display panel has been widely applied to a backlight device. In particular, FALD (Full Array) in which the LED elements are arranged in a 2D array over the entire area of the display panel. Local Dimming) method is receiving a lot of attention. Since the FALD method requires a large number of LED elements, a considerable number of pixel circuits for driving the LED elements are also required. However, if the number of pixel circuits increases, chip-to-chip uniformity may deteriorate, and manufacturing costs may increase due to an increase in components.

The technical idea of the present disclosure is a backlight driver that stores a reference current in a plurality of pixel circuits sharing a single current source in a time division method and performs a local dimming operation based on the stored reference current, a backlight device including the same, and a backlight A method of operating the device is provided.

In order to achieve the above object, a backlight device according to an aspect of the technical idea of the present disclosure includes a plurality of LED elements, and the plurality of LED elements is a backlight unit divided into a plurality of dimming groups. , a panel driver outputting a reference current for driving the plurality of LED elements and connected to the panel driver through a common line, respectively driving the first LED elements included in a corresponding dimming group among the plurality of dimming groups and a plurality of pixel circuits, wherein each of the plurality of pixel circuits converts and stores the reference current into a reference voltage in a time division manner in a first section of a frame section, and stores the converted reference current into a reference voltage in a second section of the frame section, Acquire luminance data of an image displayed by a corresponding dimming group among the plurality of dimming groups, and in a third period of the frame period, a light emission time corresponding to the obtained luminance data using the stored reference voltage while the first LED elements may be driven.

A backlight driver according to an aspect of the inventive concept includes a first pixel circuit for driving first LED elements corresponding to a first area of a display panel, and second LED elements corresponding to a second area of the display panel. a second pixel circuit for driving and a current source connected in parallel to the first pixel circuit and the second pixel circuit, wherein a reference current is provided to the first pixel circuit and the second pixel circuit based on the current source a panel driver, wherein the first pixel circuit converts and stores the reference current into a reference voltage in a first sampling period of the charging period, and displays the luminance corresponding to the first region in the display period The first LED elements are driven based on first luminance data, and the second pixel circuit converts and stores the reference current into the reference voltage in a second sampling period of the charging period, and stores the converted reference current in the display period. , the second LED elements may be driven based on second luminance data indicating luminance corresponding to the second region.

A method of driving a backlight device according to an aspect of the inventive concept includes generating a reference current using a current source in a first section of a frame section, and in the first section, N ( converting the reference current to a reference voltage in a time division manner using pixel circuits of N is a positive integer) and storing the converted reference voltage; obtaining N luminance data corresponding to each of the N regions of an image, and in a third period of the frame period, a light emission time corresponding to the N luminance data using a reference voltage stored in the N pixel circuits while driving the LED elements.

According to the backlight driver, the backlight device including the same, and the method of operating the backlight device according to an embodiment of the present disclosure, a reference current is stored in a plurality of pixel circuits sharing a single current source in a time division method, and the stored reference current is By performing the local dimming operation based on the basis, it is possible to reduce the dispersion between LEDs, thereby improving the brightness uniformity, miniaturizing the product, and reducing the manufacturing cost and power consumption.

1 is a block diagram illustrating a display device according to an embodiment of the present disclosure.
2 is a diagram illustrating a display panel and a backlight unit according to an embodiment of the present disclosure.
3 is a block diagram illustrating a backlight driver according to an embodiment of the present disclosure.
4 is a diagram illustrating operations of a backlight driver for each frame period.
5 is a diagram illustrating a pixel circuit according to an exemplary embodiment of the present disclosure.
6A and 6B are diagrams illustrating a current-voltage conversion circuit according to an embodiment of the present disclosure.
7A to 7C are diagrams illustrating a sample and hold circuit according to an embodiment of the present disclosure.
8A is a diagram illustrating a current writing operation to which a pulse width modulation (PWM) method is applied. Fig. 8b is a diagram illustrating a variant embodiment of Fig. 8a;
9 is a diagram illustrating a current writing operation to which a pulse amplitude modulation (PAM) method and a PWM method are applied.
10A to 10C are diagrams illustrating various embodiments of operations of the backlight driver for each frame section.
11 is a diagram illustrating an operation of pixel circuits for each frame section according to an embodiment of the present disclosure.
12 is a block diagram illustrating a backlight driver according to an embodiment of the present disclosure.
13 is a block diagram illustrating a backlight driver according to an embodiment of the present disclosure.
FIG. 14 is a diagram illustrating operations for each frame section of the backlight driver of FIG. 13 .
15 is a flowchart illustrating a method of driving a backlight device according to an embodiment of the present disclosure.
16 is a diagram illustrating a backlight device according to an embodiment of the present disclosure.
17 is a diagram illustrating a backlight device according to an embodiment of the present disclosure.
18 illustrates an example of a display device according to an embodiment of the present disclosure.
19 illustrates an example of a display device according to an embodiment of the present disclosure.

1 is a block diagram illustrating a display device according to an embodiment of the present disclosure.

Referring to FIG. 1 , the display apparatus 1000 includes a timing controller 1100 , a source driver 1200 , a gate driver 1300 , a display panel 1500 , a backlight unit 1500 , and a backlight driver 1600 . . In some embodiments, a configuration including the timing controller 1100 , the source driver 1200 , the gate driver 1300 , and the backlight driver 1600 may be referred to as a display driver. In some embodiments, a configuration including the backlight unit 1500 and the backlight driver 1600 may be referred to as a backlight device 1700 . In some embodiments, the display apparatus 1000 may further include components such as a voltage generator (not shown) that generates various voltages necessary for driving the display apparatus 1000, and a memory (not shown) that stores data. have.

The display apparatus 1000 according to an exemplary embodiment of the present disclosure may be mounted on an electronic device having an image display function. For example, the electronic device includes a smart phone, a tablet personal computer (PC), a portable multimedia player (PMP), a camera, a wearable device, a television, a digital video disk (DVD) player, Includes refrigerators, air conditioners, air purifiers, set-top boxes, robots, drones, various medical devices, navigation devices, global positioning system receivers, vehicle devices, furniture, or various measuring devices can do.

The timing controller 1100 may control the overall operation of the display apparatus 1000 . For example, the timing controller 1100 may control the source driver 1200 and the gate driver 1300 to display image data IDT received from an external device on the display panel 1500 .

Specifically, the timing controller 1100 generates the pixel data RGB_DT in which the format is converted to meet the interface specification with the source driver 1200 based on the image data IDT received from the outside, and the pixel data (RGB_DT) may be output to the source driver 1200 . For example, the pixel data RGB_DT may include a red component, a blue component, and a green component of each of the pixels constituting the image. Also, the timing controller 1100 may generate various control signals CTRL1 and CTRL2 for controlling the timings of the source driver 1200 and the gate driver 1300 . The timing controller 1100 may output the first control signal CTRL1 to the source driver 1200 and output the second control signal CTRL2 to the gate driver 1300 .

Also, the timing controller 1100 may generate luminance data LDT representing the luminance of an image based on the image data IDT, and output the generated luminance data LDT to the backlight driver 1600 . have. The luminance data LDT may be generated for each frame. In some embodiments, the timing controller 1100 may reflect the generated luminance data LDT to the pixel data RGB_DT.

The source driver 1200 converts the pixel data RGB_DT received from the timing controller 1100 into a plurality of image signals, for example, a plurality of data voltages, and converts the plurality of data voltages to the plurality of source lines SL1 to SLm. through the display panel 1500 . The gate driver 1300 is connected to the plurality of gate lines GL1 to GLn of the display panel 1500 and may sequentially drive the plurality of gate lines GL1 to GLn of the display panel 1500 .

The display panel 1500 is a display unit on which an actual image is displayed, and includes an organic light emitting diode (OLED) display, a thin film transistor-liquid crystal display (TFT-LCD), and a field emission display (filed). An emission display), a plasma display panel (PDP), etc. may be one of display devices that receive an electrically transmitted image signal and display a two-dimensional image. However, the present disclosure is not limited thereto, and the display panel 1500 may be implemented as another type of flat panel display or flexible display panel. Meanwhile, in the following description, the display panel 1500 will be described on the premise that it is a thin film transistor liquid crystal display implemented as an element that does not emit light by itself.

The display panel 1500 includes a plurality of gate lines GL1 to GLn, a plurality of source lines SL1 to SLm disposed in a direction crossing the plurality of gate lines GL1 to GLn, and a gate line. and a plurality of pixels PX arranged in an area where the source lines intersect.

The backlight unit 1500 may be disposed on the rear surface of the display panel 1500 to provide additional lighting to improve the contrast ratio of the display panel 1500 . To this end, the backlight unit 1500 may include a plurality of LED elements that emit light under the control of the backlight driver 1600 . The plurality of LED elements may be divided into a plurality of dimming groups corresponding to a plurality of regions of the display panel 1500 , and the number of LED elements included in the plurality of dimming groups may be the same or different, respectively. can Each of the plurality of LED devices may be implemented as a blue LED device or a white LED device, but the present disclosure is not limited thereto, and various LEDs such as a red LED device and a green LED device. It can be implemented as a device.

The backlight driver 1600 may drive a plurality of LED elements of the backlight unit 1500 in a local dimming method. Specifically, the backlight driver 1600 may control the plurality of LED elements so that the plurality of dimming groups of the backlight unit 1500 emit light with individual luminance. In some embodiments, the backlight driver 1600 may control the plurality of LED elements so that the plurality of dimming groups emit light with individual luminance using the luminance data LDT received from the timing controller 1100 .

2 is a diagram illustrating a display panel and a backlight unit according to an embodiment of the present disclosure. In detail, FIG. 2 is a view showing the display panel 1500 and the backlight unit 1500 of FIG. 1 .

The display panel 1500 may be divided into a plurality of regions in an m×n array (m and n are positive integers), and the backlight unit 1500 also has an m×n array corresponding to each of the plurality of regions. It may be divided into a plurality of dimming groups. For example, referring to FIG. 2 , the display panel 1500 may be divided into a plurality of regions in a 4×4 array, and the backlight unit 1500 may be divided into a plurality of dimming groups in a 4×4 array. . In other words, the display panel 1500 may be divided into a first area to a 16th area, and the backlight unit 1500 is divided into a first dimming group to a 16th dimming group corresponding to the first area to the 16th area, respectively. can be Meanwhile, an example of an m×n arrangement of a plurality of dimming groups is not limited to the above-described example, and various m×n arrangements may be applied, of course.

The backlight driver 1600 may check the luminance of an image displayed in each of the plurality of regions of the display panel 1500 based on the received luminance data LDT. In addition, the backlight driver 1600 may drive the backlight unit 1500 for each dimming group to emit light with brightness corresponding to the luminance of the plurality of regions. The luminance data LDT may be composed of a plurality of levels indicating a degree of luminance of an image.

For example, the backlight driver 1600 determines the luminance of an image displayed on the first area of the display panel 1500 based on the luminance data LDT, and emits light with a brightness corresponding to the determined luminance. ) can control the LED elements included in the first dimming group. A detailed description of a method of driving the backlight unit 1500 based on the luminance data LDT of the backlight driver 1600 will be described later with reference to FIG. 5 .

Meanwhile, in FIGS. 1 and 2 , the backlight driver 1600 receives the luminance data LDT and drives the backlight unit 1500 using the received luminance data LDT. However, the present disclosure is limited thereto. I never do that. For example, the backlight driver 1600 receives image data IDT or pixel data RGB_DT from the timing controller 1100, and uses the received image data IDT or pixel data RGB_DT to display panel (RGB_DT). It may be implemented to calculate the luminance of a plurality of regions of 1500 , and drive the backlight unit 1500 based on the calculated luminance.

3 is a block diagram illustrating a backlight driver according to an embodiment of the present disclosure. In detail, FIG. 3 is a diagram illustrating the backlight driver 1600 of FIG. 1 .

Referring to FIG. 3 , the backlight driver 1600 may include a panel driver 100 providing power and a pixel circuit group 200 driving a plurality of LED elements of the backlight unit 1500 based on the provided power. can The pixel circuit group 200 may include M (M is a positive integer) pixel circuits 210_1 , 210_2 , ?? and 210_M. Each of the pixel circuits 210_1 , 210_2 , ?? and 210_M drives LED elements included in at least one of a plurality of dimming groups of the backlight unit 1500 , or among LED elements included in any one dimming group. Some of them can be driven That is, each of the pixel circuits 210_1 , 210_2 , ?? and 210_M may correspond to at least a portion of a plurality of regions of the display panel 1500 . The number of LED elements driven by the pixel circuits 210_1, 210_2, ??, and 210_M may be the same or different.

The panel driver 100 and the pixel circuit group 200 control the current storage operation for driving the LED elements and the brightness of the LED elements to be driven for each frame period, which is the time allocated to each frame. An operation of storing the corresponding luminance data LDT and an operation of driving the LED elements may be repeatedly performed. Hereinafter, the operations performed within the frame period will be described in detail.

The panel driver 100 may provide the reference current to the pixel circuit group 200 in a time division manner. Specifically, the panel driver 100 may provide the reference current to the pixel circuit group 200 only in the first period of the frame period. Also, the panel driver 100 may include a pixel driver 110 and a current write controller 120 . The pixel driver 110 may include a current source 112 and a current source controller 114 , and the current source controller 114 may control the current source 112 to provide a reference current in the first period. In some embodiments, the current source controller 112 may control the magnitude of the reference current or a duty ratio of the reference current. A detailed description thereof will be described later with reference to FIGS. 8A and 8B .

Since the pixel driver 110 is connected in parallel to the pixel circuits 210_1 , 210_2 , ?? and 210_M through a common line, the reference current provided from the current source 112 is applied to the pixel circuits 210_1 , 210_2 , ?? , 210_M) may be provided in parallel. That is, the pixel circuits 210_1 , 210_2 , ?? and 210_M may share the current source 112 . In addition, the pixel circuits 210_1, 210_2, ??, and 210_M may copy and store the provided reference current. Hereinafter, for convenience of description, an operation of providing a reference current and copying and storing the provided reference current is referred to as a current writing (CW) operation. Meanwhile, the name of the operation is not limited to the above-described example, and may be referred to as a charging operation.

The current write controller 120 may output a write signal WRITE<1:M> indicating the execution time of the current write operation in response to the provision of the reference current. The write signal WRITE<1:M> may be provided through M lines connecting the current write controller 120 and the pixel circuits 210_1 , 210_2 , ?? and 210_M, respectively. For example, the write signal WRITE<1> is provided to the first pixel circuit 210_1 through a first line, and the write signal WRITE<2> is provided to the second pixel circuit 210_2 through a second line. The write signal WRITE<M> may be provided to the Mth pixel circuit 210_M through the Mth line. The pixel circuits 210_1 , 210_2 , ?? and 210_M may copy and store a reference current according to the write signal WRITE<1:M>, and drive the LED elements based on the stored reference current.

Meanwhile, since the pixel driver 110 is connected in parallel with the pixel circuits 210_1 , 210_2 , ?? and 210_M, when the pixel circuits 210_1 , 210_2 , ?? and 210_M want to simultaneously copy current. , the amount of current reaching each of the pixel circuits 210_1, 210_2, ??, and 210_M is reduced to 1/M, so the amount of copied current may not be sufficient. Accordingly, the current write controller 120 may generate the write signals WRITE<1:M> such that the execution times of the current write operations of the pixel circuits 210_1 , 210_2 , ?? and 210_M are different from each other. For example, the current write controller 120 may set the write signal WRITE<1 so that the current writing operation of the second pixel circuit 210_2 is executed after the current writing operation of the first pixel circuit 210_1 is executed. :M>) can be created. Meanwhile, since the pixel driver 110 may provide the reference current to the pixel circuits 210_1 , 210_2 , ?? and 210_M only in the first period, the pixel circuits 210_1 , 210_2 , ?? and 210_M write the current. All of the execution times of the operation may be located within the first interval.

The pixel circuits 210_1 , 210_2 , ?? and 210_M may perform a current write operation of copying and storing the reference current in a first period of the frame period. In addition, the pixel circuits 210_1 , 210_2 , ??, and 210_M may store corresponding luminance data LDT in the second period of the frame period. Here, the luminance data LDT indicates the luminance of an image displayed on a partial area of the display panel 1500 corresponding to each of the pixel circuits 210_1 , 210_2 , ?? and 210_M. For example, the luminance data LDT of the first pixel circuit 210_1 is the luminance of an image displayed in a partial region (eg, the first region) of the display panel 1500 corresponding to the first pixel circuit 210_1 . indicates

In some embodiments, the luminance data LDT may be implemented using a pulse width modulation (PWM) method. That is, the luminance data LDT may be implemented in the form of a pulse having a width corresponding to the luminance of the image. Hereinafter, for convenience of description, it is assumed that the luminance data LDT is implemented in a PWM method, and an operation of receiving and storing the luminance data LDT from the timing controller 1100 or the like is performed by reading the luminance data (luminance data). reading (LDR) operation.

In addition, the pixel circuits 210_1 , 210_2 , ?? and 210_M may drive the LED elements using the reference current stored in the third period of the frame period. In this case, the pixel circuits 210_1 , 210_2 , ?? and 210_M may drive the LED elements with brightness corresponding to the stored luminance data LDT. For example, the first pixel circuit 210_1 may drive the LED elements to emit light during an emission time corresponding to the luminance data LDT of the first pixel circuit 210_1 . As the luminance of the image displayed on the display panel 1500 increases, additional illumination of the backlight unit 1500 is required. can drive LED devices with a long light emission time. Hereinafter, for convenience of description, an operation of driving the LED elements is referred to as a light emitting operation (LE) operation.

As such, the backlight driver 1600 includes the pixel circuits 210_1 , 210_2 , ?? and 210_M configured to share the current source 112 , and can drive a plurality of LED elements based on one pixel circuit. , as the number of components is reduced, the size of the backlight driver 1600 may be reduced, and manufacturing cost may be reduced. Also, since the backlight driver 1600 provides current only in the first section of the frame section, power consumption can be reduced.

4 is a diagram illustrating operations of a backlight driver for each frame period. In detail, FIG. 4 is a diagram illustrating operations for each frame section of the backlight driver 1600 of FIG. 3 .

Referring to FIG. 4 , the backlight driver 1600 may operate in units of a frame period T_FRAME. For example, the backlight driver 1600 may first perform a current write operation CW in a frame period corresponding to the first frame FRAME 1 . In this case, the current writing operation CW may be sequentially performed for each of the pixel circuits 210_1 , 210_2 , ?? and 210_M included in the backlight driver 1600 . That is, when the backlight driver 1600 includes M pixel circuits 210_1, 210_2, ??, and 210_M as shown in FIG. 3 , the backlight driver 1600 performs a current write operation ( After performing WRITE<1>), a current writing operation WRITE<2> of the second pixel circuit 210_2 may be performed. In the above-described manner, the backlight driver 1600 may complete the current writing operation WRTIE<M> of the M-th pixel circuit 210_M. In this way, the period in which the current write (CW) operation is performed may be referred to as a first period. Meanwhile, the present disclosure is not limited thereto, and the first period may be referred to as a charging period or other names.

In addition, when the current write (CW) operation is completed, the backlight driver 1600 may perform a luminance data read (LDR) operation. That is, each of the M pixel circuits 210_1 , 210_2 , ?? and 210_M receives luminance data LDT representing the luminance of an image displayed on a partial area of the corresponding display panel 1500 from the timing controller 1100 . can be saved. In this way, a section in which the luminance data read (LDR) operation is performed may be referred to as a second section. Meanwhile, the present disclosure is not limited thereto, and the second section may be referred to as a data read period or other names.

In addition, when the luminance data reading (LDR) operation is completed, the backlight driver 1600 may perform a light emitting (LE) operation. That is, each of the M pixel circuits 210_1 , 210_2 , ?? and 210_M may drive the LED elements to emit light during an emission time corresponding to the luminance data LDT of the backlight unit 1500 . A period in which the luminance data light emission (LE) operation is performed as described above may be referred to as a third period. Meanwhile, the present disclosure is not limited thereto, and the third section may be referred to as an emission period or other names.

In some embodiments, the backlight driver 1600 may repeat the current write (CW) operation, the luminance data read (LDR) operation, and the light emitting (LE) operation for each frame period. For example, referring to FIG. 4 , the backlight driver 1600 performs a current write operation (CW), a luminance data read operation (LDR), and a light emission operation (LE) in a frame period for a first frame FRAME 1 . can be done In addition, the backlight driver 1600 may perform a current write operation CW, a luminance data read operation LDR, and a light emission operation LE in a frame period for the second frame FRAME 2 .

5 is a diagram illustrating a pixel circuit according to an exemplary embodiment of the present disclosure.

The pixel circuit 210 of FIG. 5 may correspond to any one of the pixel circuits 210_1 , 210_2 , ?? and 210_M of FIG. 3 . Referring to FIG. 5 , the pixel circuit 210 includes a current-voltage conversion circuit 220 , a sample and hold circuit 230 , an LED driver group 240 , a switching circuit 250 , and a data storage ( 260) may be included. In some embodiments, the data storage 260 may include a switching controller 2610 and a memory 263 .

In the first section of the frame section, the current-voltage conversion circuit 220 and the sample and hold circuit 230 may convert the reference current I_REF into a voltage and perform a current write operation of storing the converted voltage. . In the second section of the frame section, the data storage 260 may perform a luminance data read operation. In the third period of the frame period, the sample and hold circuit 230 , the LED driver group 240 , the switching circuit 250 , and the data storage 260 may perform a light emitting operation for driving the LED elements. Hereinafter, structures and operations of the constituent elements of the pixel circuit 210 will be described in detail.

The pixel circuit 210 may be connected to the current source 112 of the pixel driver ( FIGS. 3 and 110 ). Although not shown in FIG. 5 , the current source 112 may output the reference current I_REF under the control of the current source controller 114 . In addition, the reference current I_REF may be input to the current-voltage conversion circuit 220 of the pixel circuit 210 . The reference current I_REF may be provided during a first period in which a current write operation is performed during a frame period.

The current-voltage conversion circuit 220 receives the reference current I_REF from the current source 112 connected to the pixel circuit 210 , and converts the input reference current I_REF into a voltage to the sample and hold circuit 230 . can be printed out. For example, referring to FIG. 5 , in the current-voltage conversion circuit 220 , a drain terminal is connected to the current source 112 , and a gate terminal is connected to the drain terminal of the first transistor M1 . ) and a first resistor R1 having one end connected to the source terminal of the first transistor M1 and the other end grounded. A gate terminal of the first transistor M1 may be connected to a sample and hold circuit 230 .

In some embodiments, the current-to-voltage conversion circuit 220 receives the write signal WRITE from the current write controller ( FIGS. 3 and 120 ), and selectively converts the reference current I_REF into a voltage according to the write signal WRITE. can be converted For example, referring to FIG. 5 , the current-voltage conversion circuit 220 is disposed on a line connecting the current source 112 and the first transistor M1 , and a switch ( ) driven according to the write signal WRITE. SW1) may be further included. The write signal WRITE may be implemented as a signal having an active level during the execution time of the current write operation allocated to the pixel circuit 210 in the first period of the frame period. Accordingly, when the write signal WRITE has an active level, the switch SW1 is turned on, so that the reference current I_REF may be input to the current-voltage conversion circuit 220 . The execution time of the current write operation allocated to the pixel circuit 210 may be referred to as a sampling period or the like.

The sample and hold circuit 230 may sample and store the voltage converted by the current-voltage conversion circuit 220 . For example, referring to FIG. 5 , the sample and hold circuit 230 may include a second switch SW2 for sampling a voltage and a first capacitor C1 for holding (ie, storing) a voltage. can Also, the sample and hold circuit 230 may include a low pass filter (LPF) for removing noise. Meanwhile, the present disclosure is not limited thereto, and the low-pass filter may be omitted according to embodiments.

The sample and hold circuit 230 may selectively sample the converted voltage according to the write signal WRITE received from the current write controller 120 . In other words, the sample and hold circuit 230 may sample and store the converted voltage during the execution time of the current writing operation allocated to the pixel circuit 210 in the first period of the frame period. For example, referring to FIG. 5 , when the write signal WRITE indicates that a current write operation is to be performed, the second switch SW2 is turned on, so that the converted voltage may be sampled. In addition, the sampled voltage is stored by the first capacitor C1 and may be held when the second switch SW2 is turned off. In addition, the sample and hold circuit 230 may output the voltage held (ie, stored) in the third period during which the light emitting operation is performed among the frame period.

The LED driver group 240 may drive the LED elements of the backlight unit 1500 based on the voltage provided from the sample and hold circuit 230 . Specifically, the LED driver group 240 may drive the LED elements in the third period during which the light emitting operation is performed among the frame period. In some embodiments, the LED driver group 240 includes K LED drivers 240_1, 240_2, ??, 240_K) may be included. The K LED drivers 240_1 , 240_2 , ?? and 240_K may be connected in parallel to the sample and hold circuit 230 . For example, referring to FIG. 5 , each of the K LED drivers 240_1 , 240_2 , ?? and 240_K has a gate terminal connected to the sample and hold circuit 230 , and a drain terminal connected to the LED element. It may include a second transistor M2 to be used, and a second resistor R2 having one end connected to the source terminal of the second transistor M2 and the other end being grounded.

Meanwhile, a switching circuit 250 may be disposed between the LED driver group 240 and the LED elements. In some examples, the switching circuit 250 includes K LED drivers 240_1, 240_2, ??, 240_K and K switches disposed between the K LED elements LED_1, LED_2, ??, LED_K. (SW3_1, SW3_2, ??, SW3_K) may be included. The K switches SW3_1 , SW3_2 , ?? and SW3_K of the switching circuit 250 may be turned on or off according to the control of the switching controller 261 .

The data storage 260 may receive the enable signal EN and selectively perform a luminance data read operation according to the enable signal EN. The enable signal EN may be implemented as a signal having an active level in the second period of the frame period, and may be generated by the panel driver 100 or the timing controller 1100 . When the enable signal EN has an active level, the data storage 260 may perform a luminance data operation.

Specifically, the switching controller 261 of the data storage 260 directly receives the luminance data LDT from the timing controller 1100 in response to the enable signal EN in the second section of the frame section, or receives the memory ( 263 ) may read the luminance data LDT. The memory 263 may receive and store the luminance data LDT from the timing controller 1100 . In addition, the switching controller 261 may control the switching circuit 250 based on the obtained luminance data LDT in a third period during which a light emitting operation is performed during a frame period.

In some embodiments, the switching controller 261 may control the K switches SW3_1. SW3_2, ??, and SW3_K of the switching circuit 250 to be turned on for an emission time corresponding to the luminance data LDT. have. In some exemplary embodiments, when the luminance data LDT is implemented in a PWM manner, the switching circuit 250 operates the K switches SW3_1. SW3_2, ?? , SW3_K) can be controlled to be turned on. For example, the switching circuit 250 may control the K switches SW3_1. SW3_2, ??, and SW3_K to be turned on for a longer light emission time as the width of the pulse of the luminance data LDT is longer.

In some embodiments, the switching controller 261 is a CPU (Central Processing Unit), a processor, a microprocessor, an Application Processor (AP), a Micro Controller Unit (MCU), a microcomputer, or various types of computers, such as a mini-computer. It can be implemented in the form

6A and 6B are diagrams illustrating a current-voltage conversion circuit according to an embodiment of the present disclosure. In detail, FIGS. 6A and 6B are diagrams illustrating a deformable embodiment of the current-voltage conversion circuit 220 of FIG. 5 .

The pixel circuit 210 of FIG. 5 operates the first switch SW1 of the current-voltage conversion circuit 220 and the second switch SW2 of the sample and hold circuit 230 using one write signal WRITE. can be controlled at the same time. Since the above-described structure may be implemented by simply connecting the first switch SW1 and the second switch SW2, it may correspond to the simplest circuit.

Meanwhile, in order to stably sample the reference current I_REF, it may be advantageous that the driving timings of the first switch SW1 and the second switch SW2 are different from each other. Specifically, since the supply of the reference current I_REF must be continuously maintained while the voltage converted from the reference current I_REF is sampled, the time when the first switch SW1 operates from on to off is the second switch SW2 . It may be implemented so that it is placed after the time point of operation from on to off. Hereinafter, the pixel circuits 210a and 210b implemented so that the driving timings of the first switch SW1 and the second switch SW2 are different from each other will be described with reference to FIGS. 6A and 6B .

Referring to FIG. 6A , the pixel circuit 210a may receive a first write signal WRITE and a second write signal WRITE_D. Here, the first write signal WRITE is the same signal as the write signal WRITE of FIG. 5 . Also, the second write signal WRITE_D has a first level that is an active level at the same time point as the first write signal WRITE, but has a second level from the first level at a later time point than the first write signal WRITE. is a signal that changes to

The first write signal WRITE is used to control the operation of the second switch SW2 of the sample and hold circuit 230 , similarly to the embodiment of FIG. 5 . Meanwhile, unlike the embodiment of FIG. 5 , the current-voltage conversion circuit 220a may operate based on the second write signal WRITE_D. Accordingly, although the first switch SW1 and the second switch SW2 are turned on at the same time point, the first switch SW1 is changed to be turned off after the time point when the second switch SW2 is turned off. can

Although it has been described and illustrated that the second write signal WRITE_D has an active level at the same time as the first write signal WRITE with reference to FIG. 6A , the present disclosure is not limited thereto. For example, the second write signal WRITE_D may be implemented to have an active level at a later time point than the first write signal WRITE.

Meanwhile, instead of separately receiving the first write signal WRITE and the second write signal WRITE_D, an embodiment in which the second write signal WRITE_D is generated using the first write signal WRITE can also be implemented. do. Referring to FIG. 6B , the current-voltage conversion circuit 220b may include a delay element DE for generating a delay for a signal. For example, the delay element DE may be implemented as an analog element or a digital element such as a shift register, and may be implemented as a combination of an analog element and a digital element according to an embodiment.

The current-voltage conversion circuit 220b receives the first write signal WRITE and delays the first write signal WRITE using the delay element DE to generate the second write signal WRITE_D. can In addition, the current-voltage conversion circuit 220b may drive the first switch SW1 based on the generated second write signal WRITE_D.

7A to 7C are diagrams illustrating a sample and hold circuit according to an embodiment of the present disclosure. In detail, FIGS. 7A to 7C are diagrams illustrating a deformable embodiment of the sample and hold circuit 230 of FIG. 5 .

The sample and hold circuit 230 of FIG. 5 may sample a voltage using the second switch SW2 and store and release the voltage using the first capacitor C1 . Since the above-described structure stores a voltage using only the first capacitor C1, it may correspond to the simplest circuit.

Meanwhile, the drain voltage of the second transistor M2 included in the LED driver group 240 may change in the process of supplying or stopping the supply of current to the LED devices through the sample and hold circuit 230 . A change in the voltage of the second transistor M2 may also affect the voltage stored in the first capacitor C1 . Therefore, for the stability of the voltage stored in the first capacitor C1, an analog buffer may be additionally included. Hereinafter, the sample and hold circuits 230a and 230b including analog buffers will be described with reference to FIGS. 7A to 7C .

Referring to FIG. 7A , the sample and hold circuit 230a includes a second switch SW2, a first capacitor C1, a first OPAMP OP1, a third switch SW3, and a fourth switch SW4. can do. The sample and hold circuit 230a may further include a low pass filter LPF including the second capacitor C2, but the present disclosure is not limited thereto, and the low pass filter LPF may be omitted.

Like the sample and hold circuit 230 of FIG. 5 , the second switch SW2 samples the voltage converted by the current-voltage conversion circuit 220 , and the first capacitor C1 may store the sampled voltage. have. One end of the second switch SW2 may be connected to the current-voltage conversion circuit 220 , and the other end may be connected to one end of the first capacitor C1 . And the (-) terminal of the first OPAMP (OP1) is connected to the other end of the first capacitor (C1) and one end of the third switch (SW3), the (+) terminal is grounded, the output terminal is the third switch It may be connected to the other end of SW3 and one end of the fourth switch SW4. The other end of the fourth switch SW4 may be connected to a node between the second switch SW2 and the first capacitor C1 . The third switch SW3 and the fourth switch SW4 operate opposite to each other, so that the first capacitor C1 may hold the voltage.

Meanwhile, another type of circuit may be applied to remove AC component noise of transistors constituting the analog buffer. Referring to FIG. 7B , the sample and hold circuit 230b includes a second OPAMP (OP2), _{and changes a connection relationship between input terminals of the second OPAMP (OP2) based on a specific frequency (f MOD} ), and outputs The connection relationship of the terminals may also be implemented to change based on _{the specific frequency f MOD .} Accordingly, low-frequency noises having a large amplitude, such as flicker noise, can be effectively removed. The sample and hold circuit 230b may further include a low-pass filter LPF including the second capacitor C2 and the third resistor R3, but the present disclosure is not limited thereto. may be omitted.

7C is a circuit diagram specifically illustrating the sample and hold circuit 230b of FIG. 7B. Referring to FIG. 7C , the second OPAMP OP2 of the sample and hold circuit 230b includes the switches SW5 , SW8 , SW11 , SW12 operated according to the first switching control signal SC1 , and the second switching control signal It may include switches SW6 , SW7 , SW9 , and SW10 operating according to SC2 , a plurality of transistors M3 , M4 , M5 , M6 , and a current source I3 . The first switching control signal SC1 and the second switching control signal SC2 have a period corresponding to the reciprocal of _{the specific frequency f MOD , and are signals having opposite levels.}

Meanwhile, although not shown in FIG. 5 , the pixel circuit 210 may further include a sample and hold controller (not shown) capable of controlling the sample and hold circuits 230a and 230b. The sample and hold controller controls the first OPAMP (OP1), the third switch (SW3), and the fourth switch (SW4) of the sample and hold circuit 230a, or the second OPAMP (OP2) of the sample and hold circuit 230b ) can be controlled. In some embodiments, the sample and hold controller may be implemented in various forms, such as a CPU, a processor, a microprocessor, an AP, an MCU, a microcomputer, or a mini computer.

Meanwhile, circuits having various shapes may be applied in addition to the sample and hold circuits 230 , 230a , and 230b according to the above-described embodiments. For example, a circuit to which a half dummy switch or the like is added may be applied. In addition, the low-pass filter (LPF) is also configured as a capacitor or a circuit including an active element may be applied in addition to the embodiment including a resistor and a capacitor.

5, 7A, and 7B, one pixel circuit 210 has been described on the premise that one sample and hold circuit 230, 230a, and 230b is included, but according to an embodiment, a plurality of sample and hold circuits 230 , 230a , and 230b , and a plurality of sample and hold circuits 230 , 230a , 230b may be implemented to provide voltages to the K LED elements LED_1 , LED_2 , ??, and LED_K. For example, when n sample and hold circuits 230, 230a, and 230b are included, each sample and hold circuit 230, 230a, 230b may be implemented to provide voltage to K/n LED elements. can

In another embodiment, one pixel circuit 210 includes one sample and hold circuit 230a and 230b, and the sample and hold circuit 230a and 230b includes a plurality of analog buffers OP1 and OP2. can be implemented to That is, the sample and hold circuits 230a and 230b include only one first capacitor C1 for storing the converted voltage, and include a plurality of analog buffers OP1 and OP2 connected to the first capacitor C1. can do. The plurality of analog buffers OP1 and OP2 may be implemented to provide voltages to the K LED elements LED_1 , LED_2 , ?? and LED_K.

8A is a diagram illustrating a current writing operation to which a pulse width modulation (PWM) method is applied. Fig. 8b is a diagram illustrating a variant embodiment of Fig. 8a;

The panel driver 100 may drive the LED elements of the backlight unit 1500 by providing current to the pixel driver group 240 in various ways. The current providing method includes a PAM (Pulse Amplitude Modulation) method for changing the magnitude of current, a PWM (Pulse Width Modulation) method for changing an output duty ratio of current, and a hybrid method for simultaneously applying the PAM method and the PWM method can do.

According to the technical idea of the present disclosure, the panel driver 100 provides the reference current to the pixel circuits 210 only in the first period of the frame period, and thus may basically operate in the PWM method. As such, since the reference current is not provided throughout the frame period, the amount of current consumption may be reduced.

Meanwhile, according to a deformable embodiment, the panel driver 100 may further reduce current consumption. In detail, the panel driver 100 does not provide the reference current for every frame section, but provides the reference current for every predetermined number of frame sections, thereby further reducing current consumption. In other words, the panel driver 100 may perform a current write (CW) operation in a period (hereinafter, referred to as a current write period) corresponding to a preset number of frame sections. This embodiment may be due to the fact that, when a sufficient amount of reference current is stored by one write-in (CW) operation, the LED elements may emit light during a plurality of frame periods using the stored reference current.

For example, referring to FIG. 8A , the panel driver 100 may be implemented to provide a reference current with a current writing period T_CW corresponding to three frame periods. The panel driver 100 may provide the reference current I_REF to the pixel circuits 210 in the frame period of the first frame FRAME 1 . In addition, the panel driver 100 may omit providing the reference current I_REF in the frame period of the second frame FRAME 2 and the third frame FRAME 3 . In addition, the panel driver 100 may provide the reference current I_REF to the pixel circuits 210 again in the frame period of the fourth frame FRMAE 4 . In addition, when the reference current I_REF is provided, the panel driver 100 may also provide a write signal indicating the execution time of the current write (CW) operation. The pixel circuits 210 may perform a current write (CW) operation for storing the reference current I_REF provided in frame sections corresponding to the first frame FRAME 1 and the fourth frame FRAME 4 according to the write signal. can

The current writing period T_CW includes the capacitance of the first capacitor C1 of the sample and hold circuit 230 , the amount of leakage current of the second switch SW2 , and the second transistor M2 of the LED driving group 240 . may be set based on the temperature change characteristic of

Meanwhile, according to a deformable embodiment, the pixel circuits 210 may be divided into a plurality of groups, and a frame period in which each of the plurality of groups performs a current write operation (CW) operation may be set to be different from each other. .

For example, referring to FIG. 8B , the pixel circuits 210 may be divided into three groups. And among the three groups, the first group GROUP 1 performs a current write operation in the first frame FRAME 1 , and the second group GROUP 2 writes the current in the second frame FRAME 2 . A (CW) operation may be performed, and the third group GROUP 3 may perform a current write operation (CW) in the third frame FRAME 3 . In addition, the three groups may repeat the current writing (CW) operation for each current writing period (T_CW). The panel driver 100 may provide a write signal indicating the execution time of the current write (CW) operation for each of the three groups.

9 is a diagram illustrating a current writing operation to which a pulse amplitude modulation (PAM) method and a PWM method are applied.

In some embodiments, in order to further improve the contrast ratio of the image displayed on the display panel 1500 , the panel driver 100 may provide current in a hybrid method in which the PAM method is additionally applied from the existing PWM method. For example, when the luminance of the image displayed on the display panel 1500 is very high, when the panel driver 100 increases the size of the reference current according to the PAM method, the LED elements of the backlight unit 1500 also illuminate brighter. can be provided, so that the contrast ratio can be improved.

When the reference current is provided in the hybrid method, the panel driver 100 receives the luminance data LDT from the timing controller 1100 , determines the size of the reference current based on the received luminance data LDT, and determines the A reference current having a magnitude may be provided to the pixel circuits 210 . Since the luminance data LDT may be generated for each frame, the panel driver 100 may change the size of the reference current for each frame period.

For example, referring to FIG. 9 , the panel driver 100 receives the first luminance data of the first frame FRAME 1 , determines the magnitude of the current based on the received first luminance data, and determines the determined magnitude. A reference current I_REF1 having In addition, the pixel circuits 210 may perform a current write operation (CW) for storing the provided reference current I_REF1 . In addition, the panel driver 100 receives the second luminance data of the second frame FRAME 2 , determines the magnitude of the current based on the received second luminance data, and sets the reference current I_REF2 having the determined magnitude to the pixel. It may be provided to the circuits 210 . In addition, the pixel circuits 210 may perform a current write operation (CW) for storing the provided reference current I_REF2 .

Meanwhile, in the above example, it has been described that the panel driver 100 receives the luminance data LDT from the timing controller 1100 and determines the size of the reference current based on the luminance data LDT. does not limit For example, the panel driver 100 may be implemented to receive image data IDT or pixel RGB_DT and determine the magnitude of the reference current based on the received image data IDT or pixel RGB_DT. .

10A to 10C are diagrams illustrating various embodiments of operations of the backlight driver for each frame section.

Referring to FIG. 10A , as described above with reference to FIG. 4 , the backlight driver 1600 first performs a current write (CW) operation, then performs a luminance data read (LDR) operation, and finally performs a light emission (LE) operation. The operation may be performed in the first manner M1 of performing the operation.

Meanwhile, the current write (CW) operation and the luminance data read (LDR) operation may be performed independently of each other. Accordingly, the current write (CW) operation may be implemented to be performed later than the luminance data read (LDR) operation. For example, referring to FIG. 10A , the backlight driver 1600 performs a luminance data read (LDR) operation, a current write (CW) operation, and finally a second light emitting (LE) operation. It can operate in the manner (M2).

Alternatively, the current write (CW) operation may be implemented to be performed simultaneously with the luminance data read (LDR) operation. For example, referring to FIG. 10A , the backlight driver 1600 performs a current write (CW) operation and a luminance data read (LDR) operation at the same time, and finally performs a light emitting (LE) operation in a third method M3 ) can work.

Alternatively, the write-in current (CW) operation may be implemented to be performed simultaneously with the light-emitting (LE) operation. For example, referring to FIG. 10A , the backlight driver 1600 operates in a fourth manner M4 in which luminance data readout (LDR) and current write (CW) operation and light emission (LE) operation are simultaneously performed. can do.

Meanwhile, according to an embodiment, the backlight driver 1600 may operate in a manner in which a current write (CW) operation or a luminance data (LDR) operation is omitted. For example, the panel driver 100 may be implemented to provide the reference current for every predetermined number of frame sections, rather than providing the reference current for every frame section. In this case, the backlight driver 1600 may omit the current write (CW) operation in some frame sections.

For example, referring to FIG. 10B , the backlight driver 1600 may sequentially perform a current writing (CW) operation, a luminance data reading (LDR) operation, and a light emitting (LE) operation in the first frame FRAME 1 . have. In addition, the backlight driver 1600 may omit the current writing (CW) operation in the second frame FRAME 2 , and sequentially perform the luminance data read (LDR) operation and the light emitting (LE) operation. In this case, the backlight driver 1600 may not perform a separate operation in a section allocated to the existing current write (CW) operation. Meanwhile, the present disclosure is not limited thereto, and the backlight driver 1600 may advance the luminance data read (LDR) operation in the above section and perform the light emitting (LE) operation longer. The backlight driver 1600 may operate in the same manner as in the second frame FRAME 2 until a frame period in which a current write (CW) operation is to be performed. As such, the backlight driver 1600 may operate in a fifth manner M5 in which a current write (CW) operation is omitted in some frame sections.

As another example, when the luminance of successive frames is the same, the backlight driver 1600 may omit the luminance data reading (LDR) operation in some frame sections. For example, if the luminance of the previous frame and the current frame are the same, the luminance data LDT of the previous frame and the current frame are also the same. can In this case, the backlight driver 1600 may latch and reuse the luminance data LDT of the previous frame.

For example, referring to FIG. 10C , the backlight driver 1600 may sequentially perform a current writing (CW) operation, a luminance data reading (LDR) operation, and a light emitting (LE) operation in the first frame FRAME 1 . have. In addition, the backlight driver 1600 performs a current write (CW) operation in the second frame FRAME 2 and latches the luminance data LDT of the first frame FRAME 1 instead of the luminance data read (LDR) operation. ), and a light emitting (LE) operation may be performed. As such, the backlight driver 1600 may operate in the sixth method M6 in which the luminance data reading (LDR) operation is omitted in some frame sections.

Meanwhile, with reference to FIGS. 10B and 10C , the fifth method M5 and the sixth method M6 have been illustrated and described that the luminance data read operation (LDR) operation is performed after the current write operation (CW) operation is performed. , the technical spirit of the present disclosure is not limited thereto. For example, in the fifth method M5 and the sixth method M6, as in the first method M1 to the fourth method M4, the current write (CW) operation and the luminance data read (LDR) operation are arranged. may be changed.

Also, the first method M1 to the fifth method M5 may be applied regardless of a current providing method (eg, a PWM method or a hybrid method). That is, no matter which method of the first method M1 to the fifth method M5 is operated, the current writing (CW) operation is a time division method in which a current of a certain amount is provided according to the PWM method or a frame section according to the hybrid method. This may be performed by providing a current whose magnitude is changed for each star in a time division manner.

11 is a diagram illustrating an operation of pixel circuits for each frame section according to an embodiment of the present disclosure.

As described above with reference to FIGS. 1 to 10 , the backlight driver 1600 performs a current write (CW) operation in a first period of the frame period and a luminance data read (LDR) operation in a second period of the frame period. , and a light emitting (LE) operation may be performed in the third section of the frame section. In this case, since the current writing (CW) operation is performed by sequentially providing current to each of the pixel circuits 210 , each of the pixel circuits 210 performs current writing of the corresponding pixel circuit 210 within the first period. You can wait at any time other than the time.

Meanwhile, according to a deformable embodiment, the backlight driver 1600 individually separates sections in which a current write (CW) operation, a luminance data read (LDR) operation, and a light emitting (LE) operation are performed for each of the pixel circuits 210 . It can be implemented to have For example, the backlight driver 1600 sequentially provides current to each of the pixel circuits 210 , and each of the pixel circuits 210 may perform the following operation immediately after the current writing (CW) is completed. Meanwhile, even in this embodiment, the pixel circuits 210 may be implemented to perform the above operations with the same period (eg, the frame period T_FRAME).

For example, referring to FIG. 11 , the first pixel circuit 210_1 may perform a current write (CW) operation based on the write signal WRITE<1> in the frame period T_FRAME. In addition, when the current write (CW) operation is completed, the first pixel circuit 210_1 may then perform a luminance data read (LDR) operation. In addition, when the luminance data read (LDR) operation is completed, the first pixel circuit 210_1 may perform a subsequent light emitting (LE) operation.

In addition, the second pixel circuit 210_2 performs a current write (CW) operation based on the write signal WRITE<2> after the current write (CW) operation of the first pixel circuit 210_1 is completed in the frame period T_FRAME. can be performed. In addition, when the current write operation CW is completed, the second pixel circuit 210_2 may then perform a luminance data read operation LDR. In addition, when the luminance data read (LDR) operation is completed, the first pixel circuit 210_1 may perform a subsequent light emitting (LE) operation. Meanwhile, the light emitting (LE) operation of the second pixel circuit 210_2 may not be completed within one frame period T_FRAME, but may be performed over the next frame period.

When operating in this way, the pixel circuits 210 may perform the light emitting (LE) operation longer by utilizing the existing waiting time. Accordingly, the amount of illumination of the backlight unit 1500 may be increased even if the magnitude of the reference current is not increased.

12 is a block diagram illustrating a backlight driver according to an embodiment of the present disclosure. In detail, FIG. 12 is a block diagram illustrating a deformable embodiment of the backlight driver 1600 of FIG. 3 . Among the description of the backlight driver 2000 of FIG. 12 , a description overlapping with the description of the backlight driver 1600 of FIG. 3 will be omitted.

Referring to FIG. 12 , the backlight driver 2000 may include a panel driver 300 and a plurality of pixel circuit groups 400_1 , 400_2 , ?? and 400_N. Each of the plurality of pixel circuit groups 400_1, 400_2, ??, and 400_N may include M (M is a positive integer) pixel circuits 410_1, 410_2, ??, 410_M, and the pixel circuits (410_1, 410_2, ??, 410_M) may drive at least one LED element of the backlight unit 1500 . The number of LED elements driven by the pixel circuits 410_1, 410_2, ??, and 410_M may be the same or different. The pixel circuits 410_1 , 410_2 , ?? and 410_M may correspond to the pixel circuits 410_1 , 410_2 , ?? and 410_M of FIG. 3 .

The panel driver 300 may include a plurality of pixel drivers 310_1, 310_2, ??, and 310_N corresponding to the plurality of pixel circuit groups 400_1, 400_2, ??, and 400_N. For example, the first pixel driver 310_1 corresponds to the first pixel circuit group 400_1 , the second pixel driver 310_2 corresponds to the second pixel circuit group 400_2 , and the Nth pixel driver 310_N ) may correspond to the Nth pixel circuit group 400_N.

Each of the plurality of pixel drivers 310_1, 310_2, ??, and 310_N may include current sources 312_1, 312_2, ??, and 312_N and current source controllers 314_1, 314_2, ??, and 314_N. The plurality of pixel drivers 310_1 , 310_2 , ?? and 310_N may provide a reference current to a corresponding pixel circuit group.

The panel driver 300 may include a current write controller 320 . The current write controller 320 may output the write signal WRITE<1:M> indicating the execution time of the current write operation in response to the provision of the reference current. The write signals WRITE<1:M> may be provided through M lines L1 to LM connected to the current write controller 320 , and the M lines may include a plurality of pixel circuit groups 400_1 . , 400_2, ??, 400_N) may be connected in parallel to each of the pixel circuits 410_1, 410_2, ??, and 410_M. For example, the write signal WRITE<1> may be provided to the first pixel circuit 410_1 of each of the plurality of pixel circuit groups 400_1, 400_2, ??, and 400_N through the first line L1. have. In addition, the write signal WRITE<2> may be provided to the second pixel circuit 410_2 of each of the plurality of pixel circuit groups 400_1 , 400_2 , ?? and 400_N through the second line L2 . The write signal WRITE<M> may be provided to the M-th pixel circuit 410_M of each of the plurality of pixel circuit groups 400_1 , 400_2 , ??, and 400_N through the M-th line LM.

Compared to the backlight driver 1600 of FIG. 3 , the backlight driver 2000 of FIG. 12 includes a plurality of pixel drivers 310_1 , 310_2 , ?? and 310_N and a plurality of pixel circuit groups 400_1 , 400_2 , ?? , 400_N), but may operate in substantially the same manner as in the embodiments described above with reference to FIGS. 4 to 11 .

13 is a block diagram illustrating a backlight driver according to an embodiment of the present disclosure. In detail, FIG. 13 is a block diagram illustrating a deformable embodiment of the backlight driver 2000 of FIG. 12 . Among the description of the backlight driver 3000 of FIG. 13 , a description overlapping with the description of the backlight driver 2000 of FIG. 12 will be omitted.

Referring to FIG. 13 , the backlight driver 3000 may include a panel driver 500 and a plurality of pixel circuit groups 600_1 , 600_2 , ?? and 600_N. The plurality of pixel circuit groups 600_1 , 600_2 , ?? and 600_N may correspond to the plurality of pixel circuit groups 400_1 , 400_2 , ?? and 400_N of FIG. 12 . The panel driver 500 may include a plurality of pixel drivers 510_1 , 510_2 , ?? and 510_N corresponding to the plurality of pixel circuit groups 600_1 , 600_2 , ??, and 600_N. Each of the plurality of pixel drivers 510_1, 510_2, ??, and 510_N may include current sources 512_1, 512_2, ??, and 512_N and current source controllers 514_1, 514_2, ??, and 514_N.

The panel driver 500 may include a current write controller 520 . According to an exemplary embodiment of the present disclosure, the current write controller 520 may additionally output the write signal WRITE<0> when compared with the current write controller 320 of FIG. 12 . That is, the current write controller 520 may output the write signal WRITE<0:M> through the M+1 lines L1 to LM+1.

For example, referring to FIGS. 12 and 13 , M+1 lines of the backlight driver 3000 of FIG. 13 are write signals on the M lines L1 to LM of the backlight driver 2000 of FIG. 12 . An M+1th line LM+1 for transmitting (WRITE<0>) is added, and the M+1th line LM+1 includes a plurality of pixel circuit groups 600_1, 600_2, ??, 600_N) may be connected to each of the first pixel circuits 610_1 .

In addition, each of the first lines L1 to M-1 th lines LM-1 transmitting the write signals WRITE<1:M-1> may be additionally connected to one pixel circuit. For example, referring to FIGS. 12 and 13 , the first line L1 of FIG. 12 is connected only to the first pixel circuit 410_1 , but the first line L1 of FIG. 13 is connected with the first pixel circuit 610_1 . ) as well as the second pixel circuit 610_2 adjacent to the first pixel circuit 610_1 . Also, the second line L2 of FIG. 13 may be connected not only to the second pixel circuit 610_2 but also to a third pixel circuit (not shown) adjacent to the second pixel circuit 610_2 . Also, the M-1 th line LM - 1 of FIG. 13 may be connected not only to the M-1 th pixel circuit (not shown) but also to the M th pixel circuit 610_M adjacent to the M-1 th pixel circuit.

In summary, only one pixel circuit is connected to the M+1th line and the Mth line transmitting the write signals WRITE<0> and WRITE<M>, and the write signals WRITE<1:M-2> The first line through the M-1 th line for transmitting ? may be connected to two pixel circuits adjacent to each other. Accordingly, each of the pixel circuits 610_1 , 610_2 , ??, and 610_M may receive two write signals through two lines.

According to an exemplary embodiment of the present disclosure, the current write controller 520 may sequentially generate write signals WRITE<0:M> to have active levels. Each of the pixel circuits 610_1, 610_2, ??, and 610_M performs a current write (CW) operation based on one write signal and performs a luminance data read (LDR) operation based on another write signal. can be done

For example, referring to FIG. 13 , the first pixel circuit 610_1 performs a luminance data readout (LDR) operation based on the write signal WRITE<0> and based on the write signal WRITE<1>. A current write (CW) operation may be performed. Also, the second pixel circuit 610_2 performs a luminance data read (LDR) operation based on the write signal WRITE<1>, and performs a current write (CW) operation based on the write signal WRITE<2>. can be done In addition, the M-th pixel circuit 610_M performs a luminance data readout (LDR) operation based on the write signal WRITE<M-1> and a current write (CW) operation based on the write signal WRITE<M>. action can be performed. Meanwhile, the present disclosure is not limited thereto, and the first pixel circuit 610_1 performs a current write (CW) operation based on the write signal WRITE<0> and based on the write signal WRITE<1>. Of course, it may be implemented in a manner of performing a luminance data read (LDR) operation.

As described above, the current write controller 520 according to the present exemplary embodiment uses the write signal WRITE<0:M> including the added write signal WRITE<0> to the pixel circuits 610_1, 610_2, ?? , 610_M, the execution times of the luminance data read (LDR) operation and the current write (CW) operation may be transmitted. Accordingly, the pixel circuits 610_1, 610_2, ??, and 610_M of the present embodiment do not need to receive the enable signal EN indicating the execution time of the luminance data read (LDR) operation described above with reference to FIG. 5 . , lines for transmitting the enable signal EN to each of the pixel circuits 610_1, 610_2, ??, and 610_M may be omitted.

That is, the backlight driver 3000 of the present embodiment adds one line for transmitting the write signal WRITE<0>, thereby providing an enable signal EN to each of the pixel circuits 610_1, 610_2, ??, and 610_M. Since lines that transmit

Meanwhile, according to another deformable embodiment, the M+1th line LM+1 for transmitting the write signal WRITE<0> is connected to all of the pixel circuits 610_1, 610_2, ??, and 610_M. can be implemented. That is, like the backlight driver 2000 of FIG. 12 , the M lines L1 to LM for transmitting the write signals WRITE<1:M> are respectively connected to one pixel circuit, and the write signals WRITE<1:M> 0>), only the M+1th line LM+1 may be implemented to be connected to all of the pixel circuits 610_1, 610_2, ??, and 610_M.

In this case, the current write controller 520, as described above with reference to FIG. 12 , writes a write signal ( WRITE<1:M>) and may generate a write signal WRITE<0> indicating the execution time of the luminance data read (LDR) operation of the pixel circuits 610_1, 610_2, ??, and 610_M. . That is, the write signal WRITE<0> may serve as the enable signal EN described above in FIG. 5 . Accordingly, even in this case, lines for transmitting the enable signal EN to each of the pixel circuits 610_1, 610_2, ??, and 610_M may be omitted.

FIG. 14 is a diagram illustrating operations for each frame section of the backlight driver of FIG. 13 .

The backlight driver 3000 may also operate in units of frame sections. For example, referring to FIG. 14 , the backlight driver 3000 may simultaneously perform a current write operation (CW) and a luminance data read (LDR) operation in a frame section corresponding to the first frame FRAME 1 . .

Specifically, the write signals WRITE<0:M> may be sequentially generated to have an active level, and each of the plurality of pixel circuits 610_1 , 610_2 , ??, and 610_M provides a current according to the corresponding write signals. A write operation (CW) and a luminance data read operation (LDR) may be sequentially performed.

For example, referring to FIGS. 13 and 14 , the first pixel circuit 610_1 performs a luminance data read (LDR) operation when the write signal WRITE<0> has an active level, and the write signal WRITE<0> 1>) has an active level, a current write (CW) operation may be performed. In addition, the second pixel circuit 610_2 performs a luminance data readout (LDR) operation when the write signal WRITE<1> has an active level, and a current write (CW) operation when the write signal WRITE<2> has an active level. ) can be performed.

In addition, when the current writing operation (CW) and the luminance data reading (LDR) operation of the plurality of pixel circuits 610_1, 610_2, ??, and 610_M are completed, the backlight driver 3000 may perform a light emitting (LE) operation. have.

Meanwhile, when the write signal WRITE<0> described above in FIG. 14 is connected to all of the pixel circuits 610_1, 610_2, ??, and 610_M, the pixel circuits 610_1, 610_2, ??, and 610_M are written When the signal WRITE<0> has an active level, a luminance data read (LDR) operation is performed, and when the remaining write signals WRITE<1:M> sequentially have an active level, a current write (CW) operation is performed, respectively. can do. In addition, when the current writing (CW) operation of the pixel circuits 610_1, 610_2, ??, and 610_M is completed, the light emitting (LE) operation may be performed.

On the other hand, in the illustration and description of FIG. 14 , the write signal WRITE<0>, the write signal WRITE<1>, ??, and the write signal WRITE<M> are shown to have an active level in the order. Although described, the present disclosure is not limited thereto, and the order in which the write signals WRITE<0:M> have active levels may be implemented in various ways.

15 is a flowchart illustrating a method of driving a backlight device according to an embodiment of the present disclosure. The operation method of FIG. 15 may be performed by the backlight device 1700 of FIG. 1 .

Referring to FIG. 15 , the backlight device 1700 may generate a reference current using a current source in a first section of a frame section ( S110 ). In addition, the backlight device 1700 may convert a reference current in a time division manner using N (N is a positive integer) pixel circuits sharing a current source in the first section, and store the converted reference voltage ( S120 ). . Each of the N pixel circuits may include a conversion circuit for converting a reference current into a reference voltage, and a sample and hold circuit for sampling and storing the reference voltage.

In addition, the backlight device 1700 may acquire N pieces of luminance data corresponding to each of the N areas of the image displayed on the display panel in the second section of the frame section ( S130 ). In addition, in the third section of the frame section, the backlight device 1700 may drive the LED elements for a light emission time corresponding to the N pieces of luminance data using the reference voltages stored in the N pixel circuits ( S140 ).

16 is a diagram illustrating a backlight device according to an embodiment of the present disclosure.

Like the backlight unit 1500 described above in FIG. 2 , the backlight unit 4100 of FIG. 16 may be divided into a plurality of dimming groups, and the backlight driver 4200 divides the backlight unit 4100 into a plurality of dimming groups. can drive

In some embodiments, the backlight driver 4200 may include a plurality of panel drivers 4210 and a plurality of pixel circuit groups 4220 to drive the backlight unit 4100 for each dimming group. The panel driver 4210 and the pixel circuit group 4220 may correspond to the panel driver 100 and the pixel circuit group 200 of FIG. 3 .

The backlight unit 4100 may include the same number of a plurality of panel drivers 4210 and a plurality of pixel circuit groups 4220 . The plurality of panel drivers 4210 and the plurality of pixel circuit groups 4220 may correspond to each of the plurality of dimming groups, and may drive LED elements of the corresponding dimming group. Each of the plurality of panel drivers 4210 and the plurality of pixel circuit groups 4220 may be disposed adjacent to an area in which LED elements of the corresponding dimming group are located.

For example, referring to FIG. 16 , when the backlight unit 4100 is divided into 4×4 dimming groups, the backlight driver 4200 includes 16 panel drivers 4210 and 16 pixel circuit groups 4220 . ) may be included. The 16 panel drivers 4210 and the 16 pixel circuit groups 4220 may be disposed adjacent to an area in which a corresponding dimming group among 16 dimming groups is located.

17 is a diagram illustrating a backlight device according to an embodiment of the present disclosure. In detail, FIG. 17 is a view showing a deformable embodiment of FIG. 16 .

In some embodiments, the backlight driver 5200 may drive a plurality of dimming groups of the backlight unit 5100 for each column. For example, the backlight driver 5200 may include a plurality of panel drivers 5210 and a plurality of pixel circuit groups 5220 corresponding to columns of a plurality of dimming groups of the backlight unit 5100 . In some embodiments, the backlight driver 5200 may be disposed on a non-display portion of the backlight unit 5210 and may drive the LED elements through lines connected to the LED elements of the backlight unit 5210 . The panel driver 5210 and the pixel circuit group 5220 may correspond to the panel driver 100 and the pixel circuit group 200 of FIG. 3 .

For example, referring to FIG. 17 , when the backlight unit 5100 is divided into 4×4 dimming groups and the dimming groups are divided into 4 columns, the backlight driver 5200 corresponds to the number of columns. may include four panel drivers 5210 and four pixel circuit groups 5220 . The four panel drivers 5210 and the four pixel circuit groups 5220 may be disposed in a non-display area adjacent to a corresponding one of the four columns.

Meanwhile, with reference to FIG. 17 , it is assumed that the backlight driver 5200 includes a plurality of panel drivers 5210 and a plurality of pixel circuit groups 5220 corresponding to columns of a plurality of dimming groups of the backlight unit 5100 . Although shown and described, the present disclosure is not limited thereto. For example, in order for the backlight driver 5200 to drive the plurality of dimming groups of the backlight unit 5100 for each row, a plurality of panel drivers 5210 and a plurality of pixel circuit groups 5220 corresponding to the rows ) may be included.

18 illustrates an example of a display device according to an embodiment of the present disclosure. The display device 6000 of FIG. 18 is a device including a medium-large display panel 6400 , and may be applied to, for example, a television or a monitor.

Referring to FIG. 18 , the display device 6000 may include a timing controller 6100 , a source driver 6200 , a gate driver 6300 , a display panel 6400 , a backlight unit 6500 , and a backlight driver 6600 . can

The timing controller 6100 may include one or more ICs or modules. The timing controller 6100 may communicate with a plurality of source driver ICs (SDICs) and a plurality of gate driver ICs (GDICs) through a set interface.

The timing controller 6100 generates control signals for controlling driving timings of the plurality of source driver ICs (SDICs) and the plurality of gate driver ICs (GDICs), and transmits the control signals to the plurality of source driver ICs (SDICs) and the plurality of gates. It can be provided to a driver IC (GDIC).

The source driver 6200 includes a plurality of source driver ICs (SDICs), and the plurality of source driver ICs (SDICs) are mounted on a circuit film such as TCP, COF, FPC, etc., and attached to the display panel 6400 in a TAB method. Alternatively, it may be mounted on the non-display area of the display panel 6400 in a COG method.

The gate driver 6300 includes a plurality of gate driver ICs (GDICs), and the plurality of gate driver ICs (GDICs) are mounted on a circuit film and attached to the display panel 6400 in a TAB method, or in a COG method. 6400) may be mounted on the non-display area. Alternatively, the gate driver 6300 may be directly formed on the lower substrate of the display panel 6400 using a gate-driver in panel (GIP) method. The gate driver 6300 is formed in a non-display area outside the pixel array in which pixels are formed in the display panel 6400 , and may be formed by the same TFT process as the pixels.

The backlight driver 6600 may correspond to one of the backlight drivers 1600 , 2000 , 3000 , 4200 , and 5200 described above with reference to FIGS. 1 to 17 .

19 illustrates an example of a display device according to an embodiment of the present disclosure. The display device 7000 of FIG. 19 is a device including a small display panel 7200 , and may be applied to, for example, a mobile device such as a smart phone and a tablet PC, or a wearable device.

Referring to FIG. 19 , the display device 7000 may include a display driving circuit 7100 , a display panel 7200 , and a backlight unit 7300 . The display driving circuit 7100 may be composed of one or more ICs, and is mounted on a circuit film such as a Tape Carrier Package (TCP), a Chip On Film (COF), a Flexible Print Circuit (FPC), etc., and a Tape Automatic Bonding (TAB) It may be attached to the display panel 7200 using a method or mounted on a non-display area (eg, an area in which an image is not displayed) of the display panel 7200 using a chip on glass (COG) method.

The display driving circuit 7100 may include a source driver 7110 , a gate driver 7120 , a backlight driver 7130 , and a timing controller 7140 . The backlight driver 7130 may correspond to one of the backlight drivers 1600 , 2000 , 3000 , 4200 , and 5200 described above with reference to FIGS. 1 to 17 .

Exemplary embodiments have been disclosed in the drawings and specification as described above. Although the embodiments have been described using specific terms in the present specification, these are used only for the purpose of explaining the technical spirit of the present disclosure and are not used to limit the meaning or the scope of the present disclosure described in the claims. . Therefore, it will be understood by those of ordinary skill in the art that various modifications and equivalent other embodiments are possible therefrom. Accordingly, the true technical protection scope of the present disclosure should be defined by the technical spirit of the appended claims.

Claims (20)

A backlight device for providing illumination to a display panel, comprising:
a backlight unit including a plurality of LED elements, wherein the plurality of LED elements are divided into a plurality of dimming groups;
a panel driver outputting a reference current for driving the plurality of LED elements; and
a plurality of pixel circuits connected to the panel driver through a common line and respectively driving first LED elements included in a corresponding dimming group among the plurality of dimming groups;
Each of the plurality of pixel circuits,
In a first section of the frame section, the reference current is converted into a reference voltage in a time division manner and stored;
acquiring luminance data of an image displayed by a corresponding dimming group among the plurality of dimming groups in a second section of the frame section;
In a third section of the frame section, the first LED elements are driven using the stored reference voltage for a light emission time corresponding to the acquired luminance data. According to claim 1,
The first section of the frame section,
a plurality of sampling sections corresponding to each of the plurality of pixel circuits;
Each of the plurality of pixel circuits,
and converting the reference current into the reference voltage and storing the converted reference current in a corresponding sampling period among the plurality of sampling periods. 3. The method of claim 2,
The panel driver is
a current source for outputting the reference current in the first section of the frame section; and
a current write controller corresponding to each of the plurality of pixel circuits and outputting a plurality of write signals representing each of the plurality of sampling periods;
Each of the plurality of pixel circuits,
and converting and storing the reference current into the reference voltage based on a corresponding write signal among the plurality of write signals. 4. The method of claim 3,
Each of the plurality of pixel circuits,
a conversion circuit that converts the reference current into the reference voltage based on the corresponding write signal;
a sample and hold circuit for storing the converted reference voltage based on the corresponding write signal; and
and LED drivers for driving each of the first LED elements by using the stored reference voltage. 5. The method of claim 4,
The conversion circuit is
and delaying the corresponding write signal using a delay element, and converting the reference current into the reference voltage based on the delayed write signal. 5. The method of claim 4,
The sample and hold circuit is
a first sample and hold circuit; and a second sample and hold circuit;
The LED drivers are
first LED drivers for driving a first group of LED elements among the first LED elements based on a reference voltage stored in the first sample and hold circuit; and
and second LED drivers for driving a second group of LED elements among the first LED elements based on the reference voltage stored in the second sample and hold circuit. 5. The method of claim 4,
Each of the plurality of pixel circuits,
a switching circuit including switches connecting the first LED elements and the LED drivers; and
and a switching controller that acquires the luminance data and controls the switching circuit to drive the switches during an emission time corresponding to the acquired luminance data. 8. The method of claim 7,
The luminance data is
It is PWM (Pulse Width Modulation) data expressed as a pulse having a width corresponding to the luminance,
The switching controller is
The backlight device according to claim 1, wherein the first LED elements are driven for an emission time corresponding to the width of the PWM data. According to claim 1,
The panel driver is
a current source controller for controlling the current source to change the magnitude of the reference current;
The current source controller,
and selecting a magnitude of a reference current corresponding to the luminance data and controlling the current source to output the reference current of the selected magnitude. According to claim 1,
The first section and the second section are,
A backlight device, characterized in that at least a portion overlaps each other. According to claim 1,
The first section and the third section are,
A backlight device, characterized in that at least a portion overlaps each other. According to claim 1,
The plurality of pixel circuits,
For every preset number of frame sections, the reference current is sequentially converted into a reference voltage in a time division manner in the first section and stored;
The backlight device according to claim 1, wherein the luminance data is acquired in the second period for every frame period, and the first LED elements are driven during an emission time corresponding to the obtained luminance data in the third period. 13. The method of claim 12,
first pixel circuits among the plurality of pixel circuits,
For every frame section of the predetermined number based on the first frame section, the reference current is sequentially converted into a reference voltage in a time division manner in the first section and stored;
Second pixel circuits among the plurality of pixel circuits,
The backlight device according to claim 1 , wherein the reference current is sequentially converted into a reference voltage in a time division manner in the first section for every predetermined number of frame sections based on a second frame section and stored. According to claim 1,
The plurality of pixel circuits,
If the luminance data of the previous frame and the current frame are the same, the operation of acquiring the luminance data in the second section is omitted. A backlight driver operating in units of a frame period including a charging period and a display period, the backlight driver comprising:
a first pixel circuit for driving first LED elements corresponding to a first area of the display panel;
a second pixel circuit for driving second LED elements corresponding to a second area of the display panel; and
a panel driver comprising a current source connected in parallel with the first pixel circuit and the second pixel circuit, and providing a reference current to the first pixel circuit and the second pixel circuit based on the current source;
The first pixel circuit comprises:
In a first sampling period of the charging period, the reference current is converted into a reference voltage and stored;
driving the first LED elements based on first luminance data indicating luminance corresponding to the first region in the display period;
the second pixel circuit
In a second sampling period of the charging period, the reference current is converted into the reference voltage and stored;
and driving the second LED elements based on second luminance data indicating luminance corresponding to the second region in the display period. 16. The method of claim 15,
The panel driver is
outputting a first write signal indicating the first sampling period and a second write signal indicating the second sampling period;
The first pixel circuit comprises:
converting and storing the reference current into the reference voltage according to the first write signal;
the second pixel circuit,
and converting the reference current into the reference voltage according to the second write signal and storing the converted reference voltage. 17. The method of claim 16,
Each of the first luminance data and the second luminance data includes:
PWM data including a pulse having a width corresponding to the luminance,
The first pixel circuit comprises:
driving the first LED elements for a light emission time corresponding to a pulse width of the first luminance data;
the second pixel circuit,
The backlight driver according to claim 1, wherein the second LED elements are driven during a light emission time corresponding to a pulse width of the second luminance data. 16. The method of claim 15,
The panel driver is
and a current source controller controlling the current source to change the magnitude of the reference current or change the pulse width of the reference current. 16. The method of claim 15,
the first pixel circuit and the second pixel circuit,
The backlight driver according to claim 1 , wherein the reference current is converted into the reference voltage and stored in the display period for every predetermined number of frame periods. A method of driving a backlight device for providing illumination to a display panel, the method comprising:
generating a reference current using a current source in a first section of the frame section;
converting the reference current into a reference voltage in a time division manner using N pixel circuits (N is a positive integer) sharing the current source in the first section, and storing the converted reference voltage;
acquiring N pieces of luminance data corresponding to each of N areas of an image displayed on the display panel in a second section of the frame section; and
and driving the LED elements during a light emission time corresponding to the N pieces of luminance data using the reference voltages stored in the N pixel circuits in a third section of the frame section.
A backlight driver for driving the second LED elements.

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