WO2021025199A1

WO2021025199A1 - Display device and method for controlling same

Info

Publication number: WO2021025199A1
Application number: PCT/KR2019/009820
Authority: WO
Inventors: 정원상
Original assignee: 엘지전자 주식회사
Priority date: 2019-08-06
Filing date: 2019-08-06
Publication date: 2021-02-11

Abstract

The present invention relates to a display device and a method for controlling same, in which the difference between the maximum and minimum brightness values of a display can be reduced, when operating in variable refresh rate (VRR) mode, by performing inverse compensation control by varying the brightness of the display in response to a change in the vertical frequency of an input image. In addition, the performance of the display can be made to satisfy a certain standard by inversely compensating for changes in the luminance of a display panel according to changes in image refresh rate.

Description

Display device and control method thereof

The present invention relates to a display device and a control method thereof, and more particularly, to a display device having a variable refresh rate mode and a control method thereof.

Recently, as digital display devices have been developed and commercialized, various types of contents such as games, on-demand contents, and movies can be provided through external devices such as a computer (PC) or a game console, in addition to broadcasting received in real time.

In the case of games, unlike content with a fixed refresh rate, such as movies and TV programs, the refresh rate per second changes from time to time. Therefore, when playing games that frequently exceed the refresh rate of the display, it is easy to feel as if the screen is cut off or pushed due to the difference in display frequency between the content and the display.

To solve this problem, an adaptive synchronization technology was developed that adjusts the refresh rate of the display to the content. These technologies include AMD's FreeSync and Nvidia's G-sync technology. Recently, as the HDMI standard was updated to version 2.1, it introduced adaptive sync, G-sync, and pre-sync counterparts under the name of Game Mode Variable Refresh Rate (VRR).

However, since the display device having the VRR function has a large frequency change, the brightness of the display panel is inevitably different for each variable frequency. For example, when the display device operates in the VRR mode based on an image signal frame (48 to 120 Hz), if the brightness at 48 Hz and the brightness at 120 Hz are large, there may be problems in display performance and performance certification. .

The problem to be solved by the present invention is a display in which the deviation between the maximum and minimum brightness values of the display satisfies a predetermined reference range by varying the brightness of the display in response to the change in the refresh rate of the input image when operating in the variable refresh rate (VRR) mode. It is to provide an apparatus and a control method thereof. An object to be solved by the present invention is to provide a display device for determining an inverse brightness compensation value according to a change curve characteristic of a luminance level of a display panel according to a change in a refresh rate of an image signal, and a control method thereof.

In order to solve the above-described problems, the display device and the control method thereof according to an embodiment of the present invention inversely compensates the brightness of the display in response to a change in a refresh rate of an input image.

In order to solve the above-described problems, the display device and the control method thereof according to an embodiment of the present invention inversely compensates for brightness by varying a dimming control signal of a backlight unit in response to a change in a refresh rate of an input image.

In order to solve the above-described problems, a display device and a control method thereof according to an embodiment of the present invention include an inverse compensation table of a dimming control signal for inversely compensating for a change in luminance of a display panel in response to a change in a refresh rate of an input image. And variably outputs a barrite dimming control signal based on the inverse compensation table.

In order to solve the above-described problems, a display device and a control method thereof according to an embodiment of the present invention variably control a backlight dimming PWM duty ratio to inversely compensate for display brightness.

In order to solve the above-described problems, a display device and a control method thereof according to an embodiment of the present invention include a difference between a minimum value and a maximum value of the luminance level of the display panel according to a vertical frequency change of an image signal by PWM duty ratio compensation. The value of the PWM duty ratio compensation data is determined so that is less than or equal to a predetermined setting value.

In order to solve the above-described problems, in the display device and the control method thereof according to an embodiment of the present invention, the PWM duty ratio compensation data has a constant distribution corresponding to the change curve characteristic of the luminance level according to the vertical frequency change of the image signal. Is determined to have.

As described above, the display device and its control method according to the present invention can inversely compensate for a change in luminance of a display panel in response to a change in a refresh rate of an input image, thereby satisfying the performance of the display to a certain standard. The display device and its control method according to the present invention minimize the difference between the maximum value and the minimum value of the display brightness by inversely compensating for the change in luminance of the display panel in response to the change in the refresh rate of the input image, and meet a certain performance standard of the variable refresh rate mode. Can be satisfied.

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

2 is a graph illustrating a graph obtained by extracting luminance characteristics of the display panel 30 according to an exemplary embodiment of the present invention.

3 is a graph showing a backlight dimming PWM compensation value according to an inverse compensation table according to an embodiment of the present invention.

4 is a graph showing a luminance value measured at the front of a display panel by compensation of an inverse compensation table according to an embodiment of the present invention.

5 shows an example of constructing a data table according to an embodiment of the present invention.

6 is a control flow diagram of a display device according to an embodiment of the present invention.

7 is a graph showing a change in a refresh rate of an input video signal and a graph showing a change in a corresponding PWM duty ratio compensation value according to an embodiment of the present invention.

8 is a control block diagram illustrating an example of a display device according to another embodiment of the present invention.

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

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments make the disclosure of the present invention complete, and are common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

1 is a control block diagram of a display device according to an embodiment of the present invention. Referring to FIG. 1, a display device according to an embodiment of the present invention includes an image receiving unit 10, an image processing unit 20, a display panel 30, and a control unit 40.

The image receiving unit 10 is for receiving signals from various external devices, and may include various connectors for connection with external devices. For example, an HDMI (High Definition Multimedia Interface) connector 11 for receiving content from a PC, a set-top box or a multimedia player, an RF coaxial cable connector for receiving a broadcast signal including content from an antenna, and a component It may include a component video connector, a composite video connector, a D-sub connector, and the like. In addition, the image receiving unit 10 may include a tuner 12 or the like for receiving a broadcast signal.

The image processing unit 20 is for processing an image signal received through the image receiving unit 10 and may include a processor and a memory. The memory may store an image processing program for image processing and processed image data, or temporarily store image information output from a processor or image information received from a receiver. The processor may process image data stored in the memory using an image processing program stored in the memory to obtain various data such as image control signals required for image restoration. The image processing unit 20 may include a decoder for decoding the received image signal, an image quality processor for processing image quality, and the like, and may be provided as separate chips or a single chip.

The display panel 30 is for displaying an image on a screen, such as a liquid crystal display (LCD) panel, a light emitting diode (LED) panel, an organic light emitting diode (OLED) panel, etc. It can be implemented as The display panel 30 according to the present invention includes a display module 31, a display driver 33 for driving the display module 31, a backlight unit 35 for irradiating light to the display module 31, and a backlight unit ( It includes a backlight driver 37 for driving 35).

The backlight unit 35 may be a Cold Cathode Fluorescent Lamp (CCFL), a Light Emitting Diode (LED) lamp, and the like, and the backlight driving unit 37 is a turn-on of the backlight unit 35 Controls /off. In the present invention, it will be described as an example that the backlight unit 35 is an LED lamp.

The control unit 40 changes the image processing mode to operate in a variable refresh rate mode in which the refresh rate of an image frame reproduced on the display panel 30 is variable based on a change in the vertical frequency of the image signal received through the image receiving unit 10. , For inverse compensation control of the brightness of the display panel 30 when the variable refresh rate mode is operated, and may be implemented including a processor and a memory. The control unit 40 controls the image processing unit 20 to process the image signal received from the image receiving unit 10 and is in charge of overall control of the display device so that the processed image is displayed on the display panel 30. The control unit 40 may be provided as a single chip with the image processing unit 20 described above, or may be provided as an image processing unit and one chip of the image processing unit 20. In addition, the functions of the control unit 40 may be distributed to a plurality of chips and performed.

Here, the variable refresh rate (VRR) mode refers to an image processing mode in which, when content having a variable refresh rate (VRR) is received and played back, the refresh rate of the display device is synchronized with the refresh rate of the content to perform variable playback processing.In this specification, adaptive synchronization Technology, Dynamic Refresh Rate, Adaptive Sync, G-Sync, Free-Sync technology, etc. are used to encompass all of the same and similar technologies called by various names.

When an external device is connected to the image receiving unit 10, the controller 40 checks whether variable refresh rate (VRR) information is included through signal transmission/reception with the external device. For example, when a device is connected to the HDMI 11, DVI, or Display port, the controller 40 exchanges EDID (Extended Display Identification Data) with the connected external device to determine whether the external device supports the variable refresh rate (VRR). Can be seen. The external device checks information values of the display device, such as resolution and maximum refresh rate, through EDID exchange, and outputs an image signal according to the specifications of the display device in response.

When it is confirmed that the external device connected through the EDID exchange supports VRR, the display device operates in a variable refresh rate (VRR) mode that changes the refresh rate of the video in response to a change in the refresh rate of the input video. Control 20 and the display panel 30. The image signal received through the image receiving unit 10 includes vertical frequency information, and the vertical frequency information means an image refresh rate. For example, when the vertical frequency of the received image changes from 120Hz to 58Hz, and from 58Hz to 70Hz, the controller 40 changes the refresh rate of the image displayed on the display panel 30 from 120Hz to 58Hz and from 58Hz to 70Hz in response. The image processing unit 20 and the display panel 30 are controlled so as to be performed.

Meanwhile, when the display device operates in the VRR mode, the controller 40 controls the brightness of the display panel 30 inversely based on a change in a refresh rate of a received image signal, that is, a vertical frequency. As the vertical frequency of the image increases, the brightness of the display panel 30 increases, and as the vertical frequency decreases, the brightness of the display panel 30 decreases. In the present invention, in the VRR mode, the brightness of the display panel 30 is inversely compensated in order to prevent a deviation of the brightness of the display panel 30 from increasing according to a vertical frequency change.

The control unit 40 compensates for a dimming control signal related to the brightness of the backlight unit 35, for example, a Pulse Width Modulation (PWM) signal, thereby inversely compensating the brightness of the display panel 30. In the present invention, the brightness of the backlight unit 35 can be compensated by controlling at least one of the duty cycle and frequency of the dimming PWM signal, and in one embodiment of the present invention, controlling the PWM duty cycle, that is, the PWM duty ratio. Explain with an example.

Referring to FIG. 1, the control unit 40 includes an inverse compensation table 41 and a PWM control unit 43. The inverse compensation table 41 is a lookup table for inversely compensating the luminance of the display panel 30, and in the present invention, it includes compensation data related to the dimming control signal of the backlight unit 35, for example, dimming PWM compensation data. The PWM control unit 43 checks the PWM compensation data corresponding to the vertical frequency change of the image signal in the inverse compensation table 41, and dims the backlight driver 37 based on the PWM compensation data confirmed in the inverse compensation table 41. The PWM control signal is variable and output.

Hereinafter, PWM compensation data for compensating the brightness of the display panel 30 will be described in detail with reference to FIGS. 2 to 5.

In order to prepare the inverse compensation table 41 for inversely compensating the brightness of the display panel 30 in the VRR mode, first, the brightness of the display panel 30, that is, a characteristic of luminance, is extracted.

2 is a graph illustrating a graph obtained by extracting luminance characteristics of the display panel 30 according to an exemplary embodiment of the present invention. In FIG. 2, an x-axis represents an image refresh rate (Hz), that is, an image vertical frequency, and a y-axis represents a white luminance value of the display panel 30 and is a value measured from the front of the display panel 30. 2 is an example of a specification of the display panel 30 capable of covering an image refresh rate of 48Hz to 120Hz, and a refresh rate can be changed according to the specification of the display panel 30.

Referring to FIG. 2, it can be seen that the brightness of the display panel 30 increases as the image refresh rate increases. Specifically, the luminance value of the display panel 30 is about 272 at a minimum image refresh rate of 48 Hz, and a luminance value of 280 at a maximum image refresh rate of 120 Hz. The difference in the luminance level between the minimum refresh rate and the maximum refresh rate is 8, and the deviation value has a change amount of about 3% when compared with the maximum brightness level value 282.

In the present invention, after extracting the change in the luminance level of the display panel 30 for each vertical frequency of the image signal, an inverse compensation table 41 for the PWM compensation value is provided in response to the characteristic of the extracted luminance change. For example, the PWM compensation value of the inverse compensation table 41 according to the present invention is the difference between the minimum value, the maximum value, the maximum value and the minimum value of the luminance of the display panel 30, that is, the amount of change, or the characteristic of a curve representing the change in luminance. The maximum value, the minimum value, and the amount of change can be determined based on the like. In this embodiment, as an example, the PWM inverse compensation value is determined based on the amount of change in luminance taking into account a difference between a maximum value and a minimum value of luminance.

In FIG. 2, since the brightness of the display panel 30 has a change amount of about 3% according to the image refresh rate, the PWM compensation value of the inverse compensation table 41 may also be determined to have a change amount of 3%. For example, the PWM duty cycle is output at a constant value of 99%, and the PWM compensation value may be determined to have a change of 3%, that is, a duty ratio change of 96 to 99% according to a change in the image refresh rate.

3 is a graph showing a backlight dimming PWM compensation value according to an inverse compensation table 41 according to an embodiment of the present invention. In FIG. 3, the x-axis represents the image refresh rate (Hz), that is, the vertical frequency of the image, and the y-axis represents a PWM compensation value, for example, a PWM duty cycle value. As shown in FIG. 3, the backlight PWM duty ratio compensation value is determined so that the image refresh rate has a value of 99% to 96% at 48Hz to 120Hz, that is, a change rate of 3%. As described above, since the brightness of the display panel 30 in FIG. 2 has a change amount of about 3% according to the image refresh rate, the PWM compensation value of the inverse compensation table 41 of FIG. 3 also has a change amount of 3%. I decided. At this time, since the brightness of the display panel 30 increases as the image refresh rate increases, the PWM compensation value is determined to have a lower value as the vertical frequency of the image signal is higher, and to have a higher value as the vertical frequency is lower. The value is determined so that it can be compensated inversely.

On the other hand, the PWM compensation values of the inverse compensation table 41 are such that the difference or change between the minimum value and the maximum value of the luminance level of the display panel 30 according to the vertical frequency change of the image signal due to the compensation satisfy a predetermined setting value or less. Is determined.

A display device that supports the VRR function can receive test certification for each VRR technology, and among the certification items, there is an item related to the display brightness deviation. For example, AMD's presync must satisfy [(max luminance-min luminance)/Hz <= 0.04 nits/Hz] based on the Delta Brightness Spec. In this embodiment, as an example, the construction of the inverse compensation table 41 for the PWM compensation value to satisfy the Delta Brightness Spec criterion of AMD's FreeSync will be described.

In FIG. 2, the (max luminance-min luminance)/Hz value of the display device without PWM inverse compensation is (280-272)/120 = 0.066, which does not satisfy the Delta Brightness Spec standard of AMD's FreeSync. Can be confirmed.

FIG. 4 is a graph showing a luminance value measured from the front of the display panel 30 by compensation of the inverse compensation table 41 of FIG. 3. In FIG. 4, the x-axis represents an image refresh rate (Hz), that is, an image vertical frequency, and the y-axis represents a white luminance value of the display panel 30. Referring to FIG. 4, when the PWM duty ratio of the backlight unit 35 is inversely compensated by the inverse compensation table 41, the luminance value of the display panel 30 is almost unchanged according to the change in the image refresh rate. The minimum luminance value of the display panel 30 is 265.9 at 48Hz, and the maximum luminance is 267.2 at 88Hz. If calculated based on the Delta Brightness Spec standard of AMD's FreeSync, (267.2-265.9)/120 = 0.01, it can be confirmed that the Delta Brightness Spec standard of AMD's FreeSync is less than 0.04. In the present embodiment, the PWM compensation value is determined based on the specification of AMD's pre-sync, but the PWM compensation value may be determined based on other specifications such as G-sync other than the pre-sync.

Extraction of the brightness characteristics of the display panel 30 and determination of the inverse compensation value are performed in advance, and the inverse compensation values determined through the above-described process are constructed as a data table and stored in the controller 40 of the display device. .

5 shows an example in which the inverse compensation values of FIG. 3 are constructed as a data table. During the VRR mode operation, the PWM control unit 43 variably outputs a PWM control signal to the backlight driver 37 based on the previously stored inverse compensation table 41 according to a change in the image refresh rate. Through this, it is possible to reduce the luminance deviation of the display device according to the change of the refresh rate.

In the above-described embodiment, when determining the PWM compensation values of the inverse compensation table 41, the fluctuation width was determined in response to the luminance change amount of the display panel 30 according to the vertical frequency change. It may be determined to have a constant distribution corresponding to the change curve characteristic of the luminance level.

Meanwhile, the display device according to an embodiment of the present invention further includes a user input interface unit 50. The user input interface unit 50 is for transmitting a signal input by the user to the control unit 40 or for transmitting a signal from the control unit 40 to the user, and for communication with a remote controller that provides the user's input. May contain modules.

The display device according to the present invention includes a user menu for setting the VRR mode, and the display device performs the VRR mode only when the VRR mode is set to ON through the user input interface unit 50. That is, even if the VRR information is included in the video signal received from the external device, if the VRR mode is set to off in the display device, the VRR mode is not executed.

6 is a control flow diagram of a display device according to an embodiment of the present invention. Referring to FIG. 6, in the display device according to an embodiment of the present invention, the controller 40 checks whether the variable refresh rate (VRR) mode is turned on (S10). The display device operates in the VRR mode only when the variable refresh rate (VRR) is set to on by the user.

If the VRR mode is set to on, the controller 40 checks whether the variable refresh rate (VRR) information is included in the EDID information received from the connected external device (S11). If VRR information is included, the control unit 40 controls the image processing unit 20 and the display panel 30 to operate in the VRR mode. In addition, the PWM control unit 43 checks the PWM compensation data corresponding to the vertical frequency of the received image signal in the inverse compensation table 41 (S13), and outputs a PWM control signal to the backlight driver 37 according to the checked value. Then, the compensation control is performed (S15). Since the refresh rate of the video signal is variable, the PWM control signal output by the PWM control unit 43 is also variablely output in response thereto.

7 is a graph showing a change in a refresh rate of an input image signal and a graph showing a change in a PWM duty ratio compensation value output from the PWM control unit 43 corresponding thereto.

As shown in (a) of FIG. 7, in the VRR mode, the refresh rate of an input image is variable and input. In this case, the display device inversely compensates the display brightness using the inverse compensation table 41 for the PWM compensation value of the backlight unit 35 stored therein. It can be seen from (b) of FIG. 7 that the PWM compensation signal is varied and output according to the variable refresh rate. The PWM compensation signal is determined to be a lower value as the refresh rate (vertical frequency) of the input video signal increases, and a larger value as the refresh rate (vertical frequency) decreases, so that the display brightness can be inversely compensated.

8 is a control block diagram illustrating an example of a display device according to another embodiment of the present invention. Description of the configuration overlapping with the above-described embodiment will be omitted as necessary. Referring to FIG. 8, the display device according to an embodiment of the present invention includes an HDMI 11, a decoder 21, an LCD, an LCD driving unit, a backlight unit 35, a backlight driving unit 37, and a control unit 40. Include. This embodiment is an example in which the image quality processing unit 23 is implemented in an integrated form with the control unit 40 as compared to the embodiment of FIG. 1 described above.

Referring to FIG. 8, the display device may check whether VRR is supported through EDID exchange with an external device connected to the HDMI 11. If VRR information is included in the EDID information, the display device operates in the VRR mode.

The video signal input through the HDMI 11 is decoded through the decoder 21, and the video signal and the video control signal decoded through the decoder 21 are input to the controller 40. The image quality control unit 45 controls the image quality processing of the image quality processor 23 based on the image control signal input through the decoder 21, and the image quality processor 23 controls the image signal according to the control of the image quality control unit 45. Process. In the VRR mode, the image quality processing unit 23 variably outputs the image output frequency by synchronizing the image output frequency in response to vertical frequency information of the input image signal. At this time, the PWM control unit 43 checks the PWM compensation value corresponding to the vertical frequency of the input video signal in the inverse compensation table 41, and outputs a PWM control signal to the backlight driver 37 with the corresponding PWM compensation value. As described above, in the VRR mode, since the image refresh rate is variable, the PWM control unit 43 varies and outputs a corresponding PWM control signal.

As described above, the present invention constructs an inverse compensation table 41 that inversely compensates the brightness of the display panel in the VRR mode, and based on this, checks and outputs the PWM compensation value according to the variable image refresh rate, thereby displaying the display according to the image refresh rate change. It is possible to reduce the variation of the brightness of the panel.

Meanwhile, the method of operating a display device of the present invention may be implemented as a code that can be read by a processor on a recording medium that can be read by a processor provided in the display device. The processor-readable recording medium includes all types of recording devices that store data that can be read by the processor. Examples of recording media that can be read by the processor include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, etc., and also include those implemented in the form of carrier waves such as transmission through the Internet. . Further, the processor-readable recording medium is distributed over a computer system connected through a network, so that the processor-readable code can be stored and executed in a distributed manner.

In addition, although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the claims. In addition, various modifications are possible by those of ordinary skill in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

Claims

An image receiver for receiving an image signal from the outside;

An image processing unit processing the image signal;

A display panel displaying an image processed by the image processing unit on a screen; And

The image processing unit controls the image processing unit to vary the refresh rate of the image frame of the display panel based on a vertical frequency change of the image signal received through the image receiving unit, and reverses the brightness of the display panel based on the vertical frequency change of the image signal. A display device comprising a control unit for controlling compensation.
The method of claim 1,

The display panel includes a display module for displaying the image on a screen, a display driver for driving the display module, a backlight unit for irradiating light to the display module, and a backlight driver for driving the backlight unit;

The display apparatus according to claim 1, wherein the controller inversely compensates the brightness of the display panel by varying and outputting the dimming control signal of the backlight unit to the backlight driver based on a change in the vertical frequency of the image signal.
The method of claim 2,

The control unit includes an inverse compensation table of a dimming control signal for inversely compensating for a change in luminance of the display panel according to a change in a refresh rate of the video signal, and based on the inverse compensation table, The display device according to claim 1, wherein the dimming control signal is varied and output to the backlight driver.
The method of claim 3,

The inverse compensation table includes pulse width modulation compensation data for dimming of the backlight unit for inverse compensation of a luminance change of the display panel according to a change in a refresh rate of the image signal;

The control unit checks the pulse width modulation compensation data corresponding to the vertical frequency of the video signal input from the inverse compensation table, and outputs a pulse width modulation control signal to the backlight driver according to the pulse width modulation compensation data. Display device.
The method according to claim 1 to 4,

When the signal received from the image receiving unit includes variable refresh rate (VRR) information, the control unit is a variable refresh rate in which the image processing unit variably processes the refresh rate of the image frame in response to a vertical frequency change of the image signal. A display device, characterized in that controlling to operate in a mode.
The method of claim 5,

Further comprising a user input interface for setting the variable refresh rate mode by a user;

When the variable refresh rate mode is set and the variable refresh rate (VRR) information is included in the signal received from the image receiving unit, the image processing unit is configured to provide an image frame in response to a vertical frequency change of the image signal. A display device, characterized in that controlling to operate in the variable refresh rate mode in which the refresh rate of is variable.
The method of claim 3,

The pulse width modulation compensation data of the inverse compensation table extracts the change in the luminance level of the display panel for each vertical frequency of the image signal, and the change amount or maximum value of the pulse width modulation compensation value in response to the extracted luminance level change. A display device, characterized in that the minimum value is determined.
The method of claim 7,

The change amount or the maximum value and the minimum value of the pulse width modulation compensation value is a predetermined set value of the difference or change amount between the minimum value and the maximum value of the luminance level of the display panel according to the vertical frequency change of the image signal by pulse width modulation compensation. A display device, characterized in that it is determined to satisfy the following.
The method of claim 8,

The display device, wherein the pulse width modulation compensation value is determined to have a constant distribution corresponding to a change curve characteristic of the luminance level according to a change in a vertical frequency of the image signal.
The method of claim 8,

The pulse width modulation compensation value is determined to have a lower pulse width modulation duty ratio value as the vertical frequency of the image signal is higher, and a higher pulse width modulation duty ratio value as the vertical frequency of the image signal is lower. Display device.
An image receiver for receiving an image signal from the outside;

An image processing unit processing the image signal;

A display module displaying the image on a screen;

A backlight unit irradiating light to the display module;

A backlight driver driving the backlight unit; And

When the signal received from the image receiving unit includes variable refresh rate information, a control unit for inversely compensating the brightness of the display module by controlling the backlight driver to change the brightness of the backlight unit in response to a change in the vertical frequency of the image signal Display device comprising a.
In the control method of a display device including a processor and a display panel,

Checking whether the variable refresh rate mode for variable refresh rate processing of the video frame is set to on;

When the variable refresh rate mode is set to ON and the variable refresh rate information is included in the signal received from an external device, the image processing mode is changed so that the refresh rate of the image frame of the display panel is varied in response to the change in the refresh rate of the received video signal. Step to do; And

And inversely compensating the brightness of the display panel in response to the refresh rate of the video signal.
The method of claim 12,

Inversely compensating the brightness of the display panel, determining a compensation value of a pulse width modulation control signal for controlling the brightness of the backlight unit based on a refresh rate of the received image signal, and pulse width modulation according to the compensation value And outputting a control signal to inversely compensate the brightness of the display panel.
The method of claim 13,

The compensation value of the pulse width modulation control signal for controlling the brightness of the backlight unit is a value determined in response to a change in the luminance level of the display panel for each refresh rate of the video signal, and a change in the refresh rate of the video signal by the compensation value And a difference or change amount between a minimum value and a maximum value of the luminance level of the display panel is determined to satisfy a predetermined value or less.
The method of claim 13,

The compensation value of the pulse width modulation control signal is determined such that a higher refresh rate of the video signal has a lower pulse width modulation duty ratio, and a lower refresh rate of the video signal has a higher pulse width modulation duty ratio;

The minimum and maximum values of the compensation values of the pulse width modulation control signal are equal to or less than a predetermined set value. A method of controlling a display device, characterized in that it is determined to be satisfied.