Head-mounted display device

Abstract

A head-mounted display device is provided. The head-mounted display device includes a display module that displays an image, a calculator that includes an adapted luminance calculator that scans a first image based on a predetermined viewing angle and calculates a first adapted luminance of the first image, and a discomfort luminance calculator that calculates a first discomfort luminance based on the first adapted luminance according to an equation that models a relationship between the first adapted luminance and a first discomfort luminance at which a user feels discomfort, and a luminance controller that controls a dimming level of the display module to be equal to or less than the first discomfort luminance.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0109692, filed with the Korean Intellectual Property Office on August 28, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a head-mounted display device and a driving method thereof. Background Technology

[0004] Recently, head-mounted display devices (HMDs) have been provided as display devices mounted on a user's head to provide images to the user. HMDs typically have optical units for each of the user's left and right eyes and can be configured to provide visual images combined with audio signals. HMDs configured to provide a fully immersive experience by completely blocking the view of the real world can greatly enhance the feeling of virtual reality.

[0005] Display panels, including, for example, liquid crystal elements or organic electroluminescent elements, can be used as display elements in head-mounted display devices. Because head-mounted display devices are mounted close to the user's eyes on their head, they can cause discomfort such as fatigue, nausea, vomiting, and disorientation. Recently, various studies have been conducted to reduce user discomfort when using head-mounted display devices. Summary of the Invention

[0006] This disclosure provides a head-mounted display device that calculates an initial image brightness in response to ambient light and adjusts the image brightness from the initial image brightness to the viewing image brightness during a predetermined adaptation period to reduce eye fatigue for the user.

[0007] It can adjust the brightness of the displayed image to reduce eye strain in response to changes in the brightness of the image.

[0008] This disclosure also provides a driving method for a head-mounted display device, which can adjust the dimming level in response to changes in the brightness of the displayed image to reduce eye fatigue for the user.

[0009] According to embodiments of the present disclosure, a head-mounted display device includes a display module, a calculator, and a brightness controller. The display module displays an image. The calculator includes an adaptive brightness calculator configured to scan a first image based on a predetermined viewing angle and calculate a first adaptive brightness of the first image, and an discomfort brightness calculator configured to calculate the first discomfort brightness based on the relationship between the first adaptive brightness and a first discomfort brightness that the user feels uncomfortable. The brightness controller is configured to control the dimming level of the display module to be equal to or less than the first discomfort brightness.

[0010] The first adaptive brightness of the first image can be calculated based on a 5° viewing angle by using the white peak (Peak White) of a low-pass filter (LPF).

[0011] The first unsuitable luminance can be represented as Ld1=(17.2±0.17)×La1 (0.417±0.041) The first equation is used to calculate, where La1 is the first adapted luminance, Ld1 is the first unadapted luminance, α is 17.2 ± 0.17, and β is 0.417 ± 0.041.

[0012] The calculator may also include a frame comparator configured to determine whether a second image different from the first image has been received.

[0013] The calculator can scan a second image based on a predetermined viewing angle and calculate a second adaptive brightness for the second image.

[0014] The second adaptive brightness of the second image can be calculated based on a 5° viewing angle by using the white peak of a low-pass filter (LPF).

[0015] The uncomfortable brightness calculator may also be configured to calculate a second uncomfortable brightness based on a second comfortable brightness, and the calculator may also include an uncomfortable brightness change determiner configured to determine, according to predetermined conditions, to change a first uncomfortable brightness to a second uncomfortable brightness.

[0016] The predetermined conditions may include a 20% or greater change in the second adaptive brightness compared to the first adaptive brightness.

[0017] Preset conditions may include maintaining the altered second adaptive brightness for 2 seconds or longer.

[0018] The second unsuitable luminance is based on Ld2 = (17.2 ± 0.17) × La2 (0.417±0.041) The second equation is used for calculation, where La2 is the second adapted luminance, Ld2 is the second unsuitable luminance, α is 17.2 ± 0.17, and β is 0.417 ± 0.041.

[0019] The brightness controller can adjust the dimming level of the display module to be less than or equal to the second unsuitable brightness based on the change from the first unsuitable brightness to the second unsuitable brightness.

[0020] According to another embodiment of this disclosure, a method for driving a head-mounted display device includes: calculating a first adaptive brightness of a first image by scanning a first image based on a predetermined viewing angle; calculating a first uncomfortable brightness by means of the first adaptive brightness based on a relationship between the first adaptive brightness and a first uncomfortable brightness that the user feels uncomfortable; and controlling the dimming level of the head-mounted display device to be equal to or less than the first uncomfortable brightness.

[0021] The first adaptive brightness of the first image can be calculated based on a 5° viewing angle by using the white peak of a low-pass filter (LPF).

[0022] The first unsuitable luminance can be represented as Ld1=(17.2±0.17)×La1 (0.417±0.041) The first equation is used to calculate, where La1 is the first adapted luminance, Ld1 is the first unadapted luminance, α is 17.2 ± 0.17, and β is 0.417 ± 0.041.

[0023] The method may further include: determining whether a second image different from the first image has been received.

[0024] The method may further include: calculating a second adaptive brightness of the second image by scanning the second image based on a predetermined viewing angle.

[0025] The second adaptive brightness of the second image can be calculated based on a 5° viewing angle by using the white peak of a low-pass filter (LPF).

[0026] The method may further include: changing the first unsuitable brightness to the second unsuitable brightness based on a 20% or more change in the second adaptive brightness compared to the first adaptive brightness and maintaining the changed second adaptive brightness for 2 seconds or longer.

[0027] The second unsuitable luminance is based on Ld2 = (17.2 ± 0.17) × La2 (0.417±0.041) The second equation is used for calculation, where La2 is the second adapted luminance, Ld2 is the second unsuitable luminance, α is 17.2 ± 0.17, and β is 0.417 ± 0.041.

[0028] The method may further include: adjusting the dimming level of the second image to be less than or equal to the second uncomfortable brightness based on the change from the first uncomfortable brightness to the second uncomfortable brightness.

[0029] According to the head-mounted display device and driving method thereof described with reference to embodiments of the present disclosure, the dimming level is adjusted in response to changes in the brightness of the displayed image to reduce eye strain on the user.

[0030] However, this disclosure is not limited to the embodiments disclosed herein, and various extensions may be made without departing from the spirit and scope of this disclosure. Attached Figure Description

[0031] Figure 1 A block diagram of a head-mounted display device according to an embodiment of the present disclosure is shown.

[0032] Figure 2 Implementation shown Figure 1 A schematic view of an example of a head-mounted display device.

[0033] Figure 3 A block diagram of a head-mounted display device according to an embodiment of the present disclosure is shown.

[0034] Figure 4 It is a curve used to explain the initial image brightness and the viewed image brightness.

[0035] Figure 5 A block diagram of a calculator according to an embodiment of the present disclosure is shown schematically.

[0036] Figure 6 and Figure 7 The following is an explanation Figure 5 A block diagram illustrating the operation of the timing controller and the calculator.

[0037] Figure 8A The curves are shown based on the standard error of the viewing angle. Figure 8B It shows the basis with Figure 8A The curve showing the standard error of the pixel size corresponding to the viewing angle.

[0038] Figure 9A and Figure 9B It is a curve showing how users react to images of varying complexity, depending on the brightness level.

[0039] Figure 10 This is a flowchart of a driving method for a head-mounted display device according to an embodiment of the present disclosure. Detailed Implementation

[0040] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings, and repeated descriptions of the same constituent elements may be omitted.

[0041] Figure 1 A block diagram of a head-mounted display device (HMD) according to an embodiment of the present disclosure is shown.

[0042] Reference Figure 1A head-mounted display device (HMD) may include a processor (PRC), a memory device (MEM), input / output devices (IO), a power supply (PS), a sensing device (SD), and a display module (DM). It should be understood that the components / parts / devices included in the head-mounted display device (HMD) are not limited to... Figure 1 And can be omitted Figure 1 The elements / components / devices shown may be included, and / or other elements / components / devices may be added without departing from the scope of this disclosure.

[0043] The processor PRC can perform specific calculations or tasks. The processor PRC can control the overall operation of the head-mounted display device (HMD). For example, the processor PRC can process signals and data via input / output devices (IO), or execute applications stored in a memory device (MEM) to provide appropriate information and / or functionality to the user by processing signals and data. In implementations, the processor PRC can be a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), an application processor (AP), a communication processor (CP), or the like. The processor PRC can be connected to other components / devices via one or more buses such as an address bus, a control bus, and a data bus. Additionally, the processor PRC can be connected to an expansion bus such as a Peripheral Component Interconnect (PCI) bus.

[0044] The memory device MEM can store data used to operate the head-mounted display device HMD. The memory device MEM can store one or more applications, instructions, commands, and data used to operate the head-mounted display device HMD, and the applications are executed by the processor PRC in the head-mounted display device HMD. At least some of the applications can be downloaded from an external server (not shown) via input-output devices I / O. Additionally, for example, the memory device MEM may include non-volatile memory devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, phase change random access memory (PRAM), resistance random access memory (RRAM), magnetic random access memory (MRAM), and ferroelectric random access memory (FRAM), and / or volatile memory devices such as dynamic random access memory (DRAM), static random access memory (SRAM), and mobile DRAM.

[0045] Input-output device IO may include a camera or image input device for inputting image signals, a microphone or audio input device for inputting audio signals, a user input device (e.g., touch keys, buttons, joysticks, scroll wheels) for receiving information from a user, and output devices including audio output devices, haptic devices, optical output devices, etc., for generating output signals related to vision, hearing, or touch. A display module DM may be located within the input-output device IO.

[0046] A power supply PS provides power for operating a head-mounted display device (HMD). The power supply PS can receive an external power source and supply power (e.g., external power received from an external power source and / or internal power converted from an external power source) to corresponding components / parts / devices included in the HMD. The power supply PS may include a battery, such as an embedded battery or a replaceable battery.

[0047] The sensing device SD may include at least one sensor for sensing information about the surroundings of the head-mounted display device (HMD), user information, and similar information. For example, the sensing device SD may include, but is not limited to, a speed sensor, an acceleration sensor, a gravity sensor, a brightness sensor, a motion sensor, a fingerprint sensor, an optical sensor, an ultrasonic sensor, a thermal sensor, and similar sensors.

[0048] The display module (DM) can be connected to other components / parts / devices via a bus and / or other communication links. The display module (DM) can display information processed by the head-mounted display device (HMD).

[0049] Figure 2 Implementation shown Figure 1 A schematic view of an example of a head-mounted display device (HMD).

[0050] Reference Figure 2 A head-mounted display device (HMD) may include a display module (DM), a housing (HS), and a mounting portion (MT). The HMD can be mounted on a user's head to provide the user with various information. For example, the display module (DM) may provide visual information (e.g., images) to the user based on image signals.

[0051] In this implementation, the display module DM can provide images to each of the user's left and right eyes. The left-eye image corresponding to the user's left eye and the right-eye image corresponding to the user's right eye can be the same as or different from each other. The head-mounted display device (HMD) can provide two-dimensional (2D) images, three-dimensional (3D) images, virtual reality (VR) images, and / or 360-degree panoramic images through the display module DM. Examples of the display module DM may include, but are not limited to, liquid crystal displays (LCDs), organic light-emitting displays (OLEDs), inorganic light-emitting displays, and flexible display devices. The display module DM can be embedded in the housing HS, or can be coupled to or combined with the housing HS. The display module DM can receive commands through the housing HS.

[0052] The housing HS can be positioned in front of the user's eyes. Components / parts / devices included in the head-mounted display device (HMD) can be housed within the housing HS. Besides... Figure 1In addition to the components / parts / devices shown, the wireless communication unit, interface unit, etc., may be arranged in the housing HS. The wireless communication unit can receive image signals from an external device (not shown) by communicating wirelessly with the external device. For example, the wireless communication unit can use various communication protocols such as Bluetooth, Radio Frequency Identification (RFID), Infrared Data Association (IrDA), ZigBee, Near Field Communication (NFC), Wireless-Fidelity (Wi-Fi), and Ultra-Wideband (UWB) to communicate with the external device. The interface unit can connect the head-mounted display device (HMD) to an external device. For example, the interface unit of the head-mounted display device (HMD) may include, but is not limited to, a wired / wireless headset port, an external charger port, a wired / wireless data port, a memory card port, a port for connecting a device equipped with an identification module, an audio input / output (I / O) port, a video I / O port, and a headphone port.

[0053] The mounting part MT can be attached to the housing HS so that the head-mounted display device HMD can be fixed to the user's head. For example, the mounting part MT can be implemented as a strip or elastic band.

[0054] Figure 3 A block diagram of a head-mounted display device (HMD) according to an embodiment of the present disclosure is shown. Figure 4 It is a curve used to explain the initial image brightness and the viewed image brightness.

[0055] Reference Figure 3 and Figure 4 The display module DM of a head-mounted display device (HMD) may include a display panel 110, a timing controller 140, a data driver 150, and a scan driver 160.

[0056] According to one embodiment, the timing controller 140 may include a calculator 120 and a brightness controller 130. However, the calculator 120 and the brightness controller 130 may be located within the timing controller 140, or they may be connected to the timing controller 140 externally.

[0057] Display panel 110 can display an image based on data signal DS. Display panel 110 may include multiple data lines, multiple scan lines, and multiple pixels. For example, each pixel included in display panel 110 may include a thin-film transistor electrically connected to one of the multiple data lines and multiple scan lines, a storage capacitor connected to the thin-film transistor, and a light-emitting element connected to a driving transistor. The thin-film transistor may include a driving transistor connected to the storage capacitor.

[0058] To improve the display quality of the display module DM, the brightness of the display module DM can be adjusted according to the user's viewing environment (such as the brightness of the surrounding environment). In this case, the brightness of the surrounding environment can be adjusted by including... Figure 1 The brightness sensor in the sensing device SD shown is used for sensing.

[0059] For example, in outdoor environments with high ambient brightness, the display module DM can increase brightness to improve the visibility of the image displayed on the display panel 110, and in dark indoor environments or at night, the display module DM can reduce brightness to reduce eye fatigue for the user. Since the head-mounted display device (HMD) is mounted on the user's head, the user can react sensitively to glare and eye fatigue based on the brightness of the image displayed on the display module DM.

[0060] The timing controller 140 can receive image data RGB and control signal CON from an external device (not shown).

[0061] The timing controller 140 can selectively perform image quality correction, adaptive color correction (ACC), and / or dynamic capacitance compensation (DCC) relative to the image data RGB supplied from an external device, and output the image data RGB' to the data driver 150. Alternatively, the timing controller 140 can provide the image data RGB supplied from an external device to the data driver 150 as is. In this case, the image data RGB' is the same as the image data RGB.

[0062] The control signal CON may include a horizontal synchronization signal, a vertical synchronization signal, and a clock signal. The timing controller 140 may generate a horizontal start signal based on the horizontal synchronization signal. The timing controller 140 may generate a vertical start signal based on the vertical synchronization signal. The timing controller 140 may generate a first clock signal and a second clock signal based on the clock signal. The timing controller 140 may provide the vertical start signal and the first clock signal as a first drive signal CTL1 to the scan driver 160. The timing controller 140 may provide the horizontal start signal and the second clock signal as a second drive signal CTL2 to the data driver 150.

[0063] Calculator 120 can calculate the initial image brightness and the viewed image brightness based on the relationship between adapted ambient brightness and determined brightness. Equation 1 provides an example of a model for determining the relationship between adapted ambient brightness and determined brightness. Adapted ambient brightness refers to the brightness after the user's eyes have adapted, and determined brightness refers to the brightness at which the user does not perceive discomfort. Adapted ambient brightness and determined brightness can be determined based on an discomfort threshold or the limit of adaptation to brightness changes, beyond which the user may feel discomfort.

[0064] [Equation 1]

[0065] Log(Lth)=c1×log(Lae)+c2×log(w)+c3,

[0066] Where Lth is the fixed brightness, Lae is the ambient brightness, w is the offset, c1 is the first constant, c2 is the second constant, and c3 is the third constant.

[0067] For example, calculator 120 can use Equation 2 to calculate the initial image brightness L1 while the user is wearing the head-mounted display device (HMD), taking into account the ambient brightness Le. The ambient brightness Le can be replaced by a brightness Lu that can be arbitrarily set by the user. When an image with the initial image brightness L1 is displayed on display panel 110, the user will not experience discomfort such as glare that may occur due to sudden changes in brightness.

[0068] [Equation 2]

[0069] Log(L1)=0.904×log(Le)+0.16×log(w)+0.07

[0070] Additionally, the calculator 120 can use Equation 3 below to calculate the viewing image brightness L2 based on the calculated initial image brightness L1. When the viewing image brightness L2 is displayed on the display panel 110, the user will not experience fatigue even after viewing the image of the head-mounted display device (HMD) for a specific period of time.

[0071] [Equation 3]

[0072] Log(L2)=0.547×log(L1)+0.15×log(w)+1.09

[0073] like Figure 4 As shown, the head-mounted display device (HMD) can first provide an initial image brightness L1 during the adaptation time ta and then change the initial image brightness L1 to the viewing image brightness L2. In one embodiment, the adaptation time ta can be within 2 minutes.

[0074] Refer again Figure 3 The brightness controller 130 can change the initial image brightness L1 to the viewed image brightness L2 during a predetermined adaptation time (e.g., adaptation time ta). The timing controller 140 can store multiple gamma datasets in a lookup table (LUT). The timing controller 140 can select and output the gamma dataset G_SET based on the brightness control signal output from the brightness controller 130. The timing controller 140 can supply the gamma dataset G_SET to the data driver 150, and the data driver 150 can generate a gamma voltage based on the gamma dataset G_SET.

[0075] The data driver 150 can output a data signal DS in response to a second drive signal CTL2 received from the timing controller 140. For example, in response to a horizontal start signal and a second clock signal, the data driver 150 can output a gamma voltage corresponding to the image data as a data signal DS to the data line.

[0076] The scan driver 160 can generate a scan signal SS based on a first drive signal CTL1 received from the timing controller 140. For example, the scan driver 160 can generate the scan signal SS in response to a vertical start signal and a first clock signal, and can sequentially output the scan signal SS to the scan lines.

[0077] When an image is displayed on the display panel 110 at a viewing brightness L2, the user will not experience eye strain even after viewing the image on the head-mounted display device (HMD) for a specific period of time. After the user uses the HMD and a predetermined adaptation time has elapsed, the user's eyes continuously undergo adaptation processing in response to the brightness of the image displayed on the display module DM. If the viewing brightness L2 is not adjusted, the user may experience discomfort such as glare or eye fatigue due to sudden changes in image brightness.

[0078] By adjusting the dimming level of the display module DM in response to changes in image brightness, the head-mounted display device (HMD) according to embodiments of the present disclosure can reduce user eye fatigue and improve display quality. Hereinafter, a detailed description of the head-mounted display device (HMD) and its driving method according to embodiments of the present disclosure will be provided.

[0079] Figure 5 An embodiment according to this disclosure is illustrated schematically. Figure 3 A block diagram of calculator 120.

[0080] Reference Figure 5 The calculator 120 may include a frame comparator 121, an adaptive brightness calculator 122, an unsuitable brightness change determiner 123, and an unsuitable brightness calculator 124.

[0081] Frame comparator 121 can determine whether a new image different from the previous image has been received. According to an embodiment, frame comparator 121 can determine whether a new image has been received based on changes in the average brightness of the image. For example, when m frames (m is an integer) of an image with a first brightness are displayed on the display module DM, and then an image with a second brightness different from the first brightness is received after those m frames, frame comparator 121 can determine that a new image different from the previous image has been received. When frame comparator 121 determines that a new image different from the previous image has been received, frame comparator 121 can provide a first control signal CS1 to instruct the adaptive brightness calculator 122 to calculate the adaptive brightness La of the new image.

[0082] In response to a first control signal CS1 received from frame comparator 121, adaptive brightness calculator 122 calculates the adaptive brightness La of the new image and provides the calculated adaptive brightness La of the new image to adaptive brightness change determiner 123. According to an embodiment, adaptive brightness calculator 122 can calculate the adaptive brightness La of the new image by scanning the entire area of ​​the new image based on a predetermined viewing angle. See below for further details. Figure 6 and Figure 7 The calculation of the adaptive luminance La is described in detail.

[0083] In response to the adaptive brightness La received from the adaptive brightness calculator 122, the uncomfort brightness change determiner 123 can determine, based on predetermined conditions, the uncomfort brightness Ld of the previous image to be changed. Uncomfort brightness refers to the brightness at which a user adapted to the adaptive brightness begins to feel discomfort. According to an embodiment, when the adaptive brightness La of the new image received from the adaptive brightness calculator 122 is changed from the adaptive brightness La of the previous image by a predetermined ratio or greater, and the adaptive brightness La of the new image remains unchanged for a predetermined time or longer, the uncomfort brightness change determiner 123 can provide a second control signal CS2 to the uncomfort brightness calculator 124 to indicate the change of the uncomfort brightness Ld of the previous image.

[0084] In response to the second control signal CS2 received from the unsuitable brightness change determiner 123, the unsuitable brightness calculator 124 can calculate the unsuitable brightness Ld for the new image.

[0085] According to the implementation method, based on Equation 4 below, which models the relationship between adaptive brightness La and unsuitable brightness Ld, the unsuitable brightness calculator 124 can calculate the unsuitable brightness Ld from the adaptive brightness La of the new image. (See below for further details.) Figure 6 and Figure 7 The calculation of the unsuitable luminance Ld is described in detail.

[0086] [Equation 4]

[0087] Ld=α×La β (Where, La is the adaptive luminance, Ld is the unsuitable luminance, α is the first coefficient, and β is the second coefficient.)

[0088] Figure 6 and Figure 7 The timing controller 140 and are shown for explanation. Figure 5 A flowchart illustrating the operation of calculator 120. Figure 6 The case of receiving the first image IMG1 is shown, and Figure 7 The case of receiving a second image IMG2, which is different from the first image IMG1, is illustrated. The first image IMG1 may correspond to the viewing image brightness L2 described above (see...). Figure 4 (Image of ).

[0089] Reference Figure 6 When frame comparator 121 receives the first image IMG1, since there is no previous image to compare it with, frame comparator 121 can regard the first image IMG1 as a new image. Accordingly, frame comparator 121 determines that a new image has been received, and frame comparator 121 can provide the first control signal CS1 to the adaptive brightness calculator 122 to instruct the calculation of the first adaptive brightness La1 of the first image IMG1.

[0090] In response to the first control signal CS1 received from the frame comparator 121, the adaptive brightness calculator 122 can calculate the first adaptive brightness La1 of the first image IMG1 and provide the first adaptive brightness La1 to the adaptive brightness change determiner 123.

[0091] According to an embodiment, the adaptive brightness calculator 122 can calculate the first adaptive brightness La1 of the first image IMG1 by scanning (or blurring) the entire area of ​​the first image IMG1 based on a predetermined viewing angle. For example, the adaptive brightness calculator 122 can calculate the first adaptive brightness La1 of the first image IMG1 based on a 5° viewing angle by using the white peak of a low-pass filter (LPF).

[0092] Figure 8A The curves are shown based on the standard error of the viewing angle. Figure 8B It shows the basis with Figure 8A The curve showing the standard error of the pixel size corresponding to the viewing angle.

[0093] Reference Figure 8A When from an image (e.g., Figure 6 The first image (IMG1) was used as a reference with a 5° viewing angle to obtain adaptive brightness using the white peak of the LPF (e.g., Figure 6When the first adaptive brightness (La1) is reached, the standard error between the physical brightness level of the image and the brightness level perceived by the user can be minimized. Conversely, when adaptive brightness is obtained by using the white peak of the LPF from a viewing angle of less than 5° or greater than 5° from the image as a reference, it can be seen that the standard error between the physical brightness level and the brightness level perceived by the user increases from the minimum standard error of the 5° viewing angle.

[0094] For example, in all images, suppose the region corresponding to a 1° viewing angle has a density of 100 cd / m². 2 The brightness, when adjusted for a 5° viewing angle by using the white peak of the LPF, is 100 cd / m². 2 One-fifth of the brightness level (i.e., 20 cd / m²) 2 The perceived area corresponds to a 1° viewing angle. That is, when the image's adaptive brightness is obtained by using the white peak of the LPF, the impact of peaks in small areas that are difficult for the user to perceive can be reduced.

[0095] Typically, head-mounted display devices (HMDs) have a viewing angle of 110° to 120°. This is a viewing angle similar to that of a user looking straight ahead without shifting their eyes from one side to the other. (See reference...) Figure 8B The size of the area corresponding to a 5° viewing angle can correspond to the size of approximately 41 pixels in the display panel 110 of the head-mounted display device (HMD). That is, when calculating the adaptive brightness by scanning (or blurring) the image in units of 41 pixels, a similar effect can be expected as when calculating the adaptive brightness by scanning (or blurring) the image in units of 5° viewing angle.

[0096] Return to reference Figure 6 The unsuitable brightness change determiner 123 can determine and calculate a first unsuitable brightness Ld1 based on predetermined conditions. According to an embodiment, when the adaptive brightness La of a new image received from the adaptive brightness calculator 122 changes by a predetermined ratio or a larger ratio from the adaptive brightness La of a previous image, and the adaptive brightness La of the new image remains unchanged for a predetermined time or longer, the unsuitable brightness change determiner 123 can provide a second control signal CS2 to the unsuitable brightness calculator 124 to indicate a change in unsuitable brightness Ld.

[0097] Since the first adaptive brightness La1 obtained from the first image IMG1 does not have a previous adaptive brightness to be compared with, it can be considered to meet the predetermined conditions. Accordingly, the unsuitable brightness change determiner 123 can provide the second control signal CS2 to the unsuitable brightness calculator 124 to instruct the calculation of the first unsuitable brightness Ld1 of the first image IMG1.

[0098] In response to the second control signal CS2 received from the unsuitable brightness change determiner 123, the unsuitable brightness calculator 124 can calculate the first unsuitable brightness Ld1 for the first image IMG1.

[0099] According to the implementation method, the first coefficient (α) and the second coefficient (β) of Equation 4 can be obtained based on Equation 5 below. Equation 5 is a psychophysical logarithmic function. For example, based on the user's adaptation and selection of images of different complexities, the first coefficient (α) and the second coefficient (β) of Equation 4 can be obtained based on the user's response as an unsuitable brightness level according to Equation 5. In this case, the complexity of the image can vary according to the proportion of areas with brightness greater than the average brightness of the image.

[0100] [Equation 5]

[0101]

[0102] Where x is the adaptive brightness for each image.

[0103] Figure 9A and Figure 9B It is a curve representing the user's response to images of varying complexity, in terms of different brightness levels.

[0104] Reference Figure 9A and Figure 9B , Figure 9A The text illustrates user reactions to images displaying ordinary objects at inappropriate brightness levels, and... Figure 9B The image shows user reactions to a sunset displayed at an inappropriate brightness level.

[0105] like Figure 9A and Figure 9B As can be seen, the degree to which users perceive discomfort from an image can vary depending on the image's complexity. The closer the value is to 1 on the vertical axis, the higher the level of user discomfort (e.g., the user's eyes are tired), while the closer it is to 0, the lower the level of user discomfort (e.g., the user's eyes are not tired).

[0106] For example, when the user displays Figure 9B In the sunset image shown, it is assumed that the brightness of the head-mounted display (HMD) is the same (e.g., 25 cd / m²). 2 ), then it is consistent with the user's adaptation of 4cd / m 2 and 8cd / m 2 Compared to the previous period, when users adapted to 2 cd / m 2 Users are more likely to experience eye fatigue at this time.

[0107] Additionally, assuming that the brightness of head-mounted display devices (HMDs) is the same (e.g., 15 cd / m²),... 2And users adapt to the same brightness (2 cd / m²). 2 ), then, compared to the display during viewing Figure 9A Compared to viewing images of ordinary objects, when viewing a display... Figure 9B Users are more likely to experience eye strain when viewing sunset images.

[0108] According to the implementation method, based on the user's adaptation and selection of images with different complexities, the user's reaction can be extracted as an uncomfortable brightness level according to Equation 5. For example, when the brightness perceived by the user closely matches the physical brightness of the image, the first coefficient (α) of Equation 4 can be set to 17.2 ± 0.17, and its second coefficient (β) can be set to 0.417 ± 0.041. In this case, Equation 6 can be obtained as follows. The uncomfortable brightness calculator 124 can calculate the first uncomfortable brightness Ld1 based on Equation 6 using the first adapted brightness La1 of the first image IMG1.

[0109] [Equation 6]

[0110] Ld1=(17.2±0.17)×La1 (0.417±0.041)

[0111] Wherein, La1 is the first adaptive luminance, and Ld1 is the first unsuitable luminance.

[0112] The brightness controller 130 can generate a first brightness control signal LCTL1 corresponding to the first unsuitable brightness Ld1 received from the unsuitable brightness calculator 124, and output the first brightness control signal LCTL1 to the memory 145.

[0113] Memory 145 can store multiple gamma datasets. These gamma datasets can be provided to data driver 150 to determine gamma voltages between gamma reference voltages. When the gamma voltage changes due to the gamma datasets, the brightness of the image can change. In this case, memory 145 can correspond to... Figure 1 The memory device MEM described in [the document].

[0114] The timing controller 140 can output a first gamma dataset G_SET1, which corresponds to the first brightness control signal LCTL1, from among multiple gamma datasets stored in the memory 145. In an embodiment, the timing controller 140 can set the dimming level of the display panel 110 to be equal to or less than the first unsuitable brightness Ld1.

[0115] Reference Figure 7Frame comparator 121 receives the second image IMG2 and compares the average brightness of the first image IMG1 and the second image IMG2. When the average brightness of the first image IMG1 and the second image IMG2 is different from each other, frame comparator 121 can determine the second image IMG2 as a new image and provide a first control signal CS1 to the adaptive brightness calculator 122 to instruct the calculation of the second adaptive brightness La2 of the second image IMG2.

[0116] In response to the first control signal CS1 received from the frame comparator 121, the adaptive brightness calculator 122 can calculate the second adaptive brightness La2 of the second image IMG2 and provide the second adaptive brightness La2 to the unsuitable brightness change determiner 123.

[0117] According to an embodiment, the adaptive brightness calculator 122 can calculate the second adaptive brightness La2 of the second image IMG2 by scanning (or blurring) the entire area of ​​the second image IMG2 based on a predetermined viewing angle. For example, the adaptive brightness calculator 122 can calculate the second adaptive brightness La2 of the second image IMG2 based on a viewing angle of 5° by using the white peak of the LPF.

[0118] The unsuitable brightness change determiner 123 can determine to change the unsuitable brightness according to predetermined conditions. According to an embodiment, when the second adaptive brightness La2 of the second image IMG2 received from the adaptive brightness calculator 122 is changed from the first adaptive brightness La1 of the first image IMG1 by a predetermined ratio or greater, and the changed second adaptive brightness La2 of the second image IMG2 is maintained for a predetermined time or longer, the unsuitable brightness change determiner 123 can provide a second control signal CS2 to the unsuitable brightness calculator 124 to indicate a change in the current unsuitable brightness Ld (in this case, the first unsuitable brightness Ld1).

[0119] For example, when the second adaptive brightness La2 of the second image IMG2 changes by 20% or more compared to the first adaptive brightness La1 of the first image IMG1, and the changed second adaptive brightness La2 of the second image IMG2 remains for 2 seconds or longer, the unsuitable brightness change determiner 123 can determine to change the first unsuitable brightness Ld1 to the second unsuitable brightness Ld2. In this case, the unsuitable brightness change determiner 123 can provide a second control signal CS2 to the unsuitable brightness calculator 124 to indicate that the first unsuitable brightness Ld1 is changed to the second unsuitable brightness Ld2.

[0120] In response to the second control signal CS2 received from the unsuitable brightness change determiner 123, the unsuitable brightness calculator 124 can calculate a second unsuitable brightness Ld2 for the second image IMG2. According to an embodiment, the unsuitable brightness calculator 124 can calculate the second unsuitable brightness Ld2 based on the second suitable brightness La2 of the second image IMG2 using the following equation 7.

[0121] [Equation 7]

[0122] Ld2=(17.2±0.17)×La2 (0.417±0.041)

[0123] Among them, La2 is the second adaptive luminance, and Ld2 is the second unsuitable luminance.

[0124] The brightness controller 130 can generate a second brightness control signal LCTL2 corresponding to the second unsuitable brightness Ld2 received from the unsuitable brightness calculator 124, and output the second brightness control signal LCTL2 to the memory 145.

[0125] The timing controller 140 can output a second gamma dataset G_SET2, which corresponds to the second brightness control signal LCTL2, from among multiple gamma datasets stored in the memory 145. In other words, the timing controller 140 can adjust the dimming level of the display panel 110 to a level equal to or less than the second unsuitable brightness Ld2.

[0126] Figure 10 This is a flowchart of a driving method for a head-mounted display device (HMD) according to an embodiment of the present disclosure.

[0127] Reference Figure 10 The driving method for a head-mounted display device (HMD) may include: determining whether a new image different from a previous image has been received (S10); calculating adaptive brightness by scanning the new image based on a predetermined viewing angle (S20); determining whether the difference in adaptive brightness between the previous image and the new image is a predetermined ratio or greater and whether it is maintained for a predetermined time (S30); calculating unsuitable brightness using the adaptive brightness of the new image (S40); and setting a dimming level equal to or less than the unsuitable brightness of the new image (S50). In the following text, for the convenience of better understanding and description, the brightness L2 of the viewed image (see above) will be used for... Figure 4 The methods for calculating the first adaptive brightness La1 and the first unadaptive brightness Ld1 from the first image IMG1 and the methods for calculating the second adaptive brightness La2 and the second unadaptive brightness Ld2 from the second image IMG2, which is different from the first image IMG1, are described separately.

[0128] Reference Figure 6 and Figure 10The driving method of the head-mounted display device (HMD) may include: determining whether a new image different from the previous image (i.e., the first image IMG1) is received (S10).

[0129] Frame comparator 121 can receive a first image IMG1 with viewing image brightness L2 (see [link]). Figure 4 Since there is no previous image to be compared with the first image IMG1, the first image IMG1 is regarded as a new image.

[0130] Next, the adaptive brightness (i.e., the first adaptive brightness La1) of the first image IMG1 can be calculated based on a predetermined viewing angle by scanning a new image (i.e., the first image IMG1) (S20).

[0131] According to an embodiment, the adaptive brightness calculator 122 can calculate the first adaptive brightness La1 of the first image IMG1 by scanning (or blurring) the entire area of ​​the first image IMG1 based on a predetermined viewing angle. For example, the first adaptive brightness La1 of the first image IMG1 can be calculated based on a viewing angle of 5° by using the white peak of the LPF.

[0132] Next, it can be determined whether the difference in adaptive brightness between the previous image and the first image IMG1 is equal to or greater than a predetermined ratio and whether it is maintained for a predetermined time (S30).

[0133] Since the first adaptive brightness La1 of the first image IMG1 does not have a previous adaptive brightness to be compared with, the unsuitable brightness change determiner 123 can be regarded as meeting the predetermined conditions.

[0134] Next, the first unsuitable brightness Ld1 can be calculated from the first suitable brightness La1 of the first image IMG1 (S40).

[0135] According to an implementation, the first unsuitable luminance Ld1 can be calculated based on Equation 4. The first coefficient (α) and the second coefficient (β) included in Equation 4 can be obtained through Equation 5. In one implementation, the first coefficient (α) can be set to 17.2 ± 0.17, and the second coefficient (β) can be set to 0.417 ± 0.041. For example, the unsuitable luminance calculator 124 can calculate the first unsuitable luminance Ld1 based on Equation 6.

[0136] Next, the dimming level can be set to a first unsuitable brightness Ld1 less than or equal to that of the first image IMG1 (S50).

[0137] The brightness controller 130 can output a first brightness control signal LCTL1 corresponding to the first unsuitable brightness Ld1 to the memory 145. The timing controller 140 can output the first gamma dataset G_SET1, which corresponds to the first brightness control signal LCTL1, from among the multiple gamma datasets stored in the memory 145. In other words, the timing controller 140 can set the dimming level of the display panel 110 to be equal to or less than the level of the first unsuitable brightness Ld1.

[0138] Reference Figure 7 and Figure 10 The driving method of the head-mounted display device (HMD) may include: determining whether a second image IMG2, which is different from the first image IMG1, is received (S10).

[0139] Frame comparator 121 can receive a second image IMG2 and compare the average brightness of the first image IMG1 and the second image IMG2. When the average brightness of the first image IMG1 and the second image IMG2 is different from each other, frame comparator 121 can determine the second image IMG2 as a new image.

[0140] Next, the adaptive brightness (i.e., the second adaptive brightness La2) of the second image IMG2 can be calculated based on a predetermined viewing angle by scanning a new image (i.e., the second image IMG2) (S20).

[0141] According to an embodiment, the adaptive brightness calculator 122 can calculate the second adaptive brightness La2 of the second image IMG2 by scanning (or blurring) the entire area of ​​the second image IMG2 based on a predetermined viewing angle. For example, the second adaptive brightness La2 of the second image IMG2 can be calculated based on a viewing angle of 5° by using the white peak of the LPF.

[0142] Next, it can be determined whether the difference between the first adaptive brightness La1 of the first image IMG1 and the second adaptive brightness La2 of the second image IMG2 is equal to or greater than a predetermined ratio and whether it is maintained for a predetermined time (S30).

[0143] According to the implementation, when the second adaptive brightness La2 of the second image IMG2 changes by 20% or more compared to the first adaptive brightness La1 of the first image IMG1, and the changed second adaptive brightness La2 of the second image IMG2 is maintained for 2 seconds or longer, the unsuitable brightness change determiner 123 can determine to change the first unsuitable brightness Ld1 to the second unsuitable brightness Ld2.

[0144] Next, the second unsuitable brightness Ld2 can be calculated from the second suitable brightness La2 of the second image IMG2 (S40).

[0145] According to an implementation, the second unsuitable luminance Ld2 can be calculated based on Equation 4. The first coefficient (α) and the second coefficient (β) included in Equation 4 can be obtained through Equation 5. In one implementation, the first coefficient (α) can be set to 17.2 ± 0.17, and the second coefficient (β) can be set to 0.417 ± 0.041. For example, the unsuitable luminance calculator 124 can calculate the second unsuitable luminance Ld2 based on Equation 7.

[0146] Next, the dimming level can be set to a second unsuitable brightness Ld2 that is less than or equal to that of the second image IMG2 (S50).

[0147] The brightness controller 130 can output a second brightness control signal LCTL2 corresponding to the second unsuitable brightness Ld2 to the memory 145. The timing controller 140 can output a second gamma dataset G_SET2 corresponding to the second brightness control signal LCTL2 from among multiple gamma datasets stored in the memory 145. In other words, the timing controller 140 can adjust the dimming level of the display panel 110 to a level equal to or less than the first unsuitable brightness Ld2.

[0148] By adjusting the dimming level of the display module DM in response to changes in image brightness, the driving method of the head-mounted display device (HMD) according to embodiments of the present disclosure can reduce user eye fatigue and improve display quality.

[0149] Although this disclosure has been described in conjunction with various embodiments, it will be understood that this disclosure is not limited to the described embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of this disclosure, including the appended claims.

Claims

1. A head-mounted display device, comprising: A display module, wherein the display module is used to display images; Calculator, the calculator comprising: An adaptive brightness calculator, configured to scan a first image based on a predetermined viewing angle and calculate a first adaptive brightness of the first image; and An uncomfortable brightness calculator, wherein the uncomfortable brightness calculator is configured to calculate the first uncomfortable brightness based on the relationship between the first adapted brightness and a first uncomfortable brightness that the user feels uncomfortable with; and A brightness controller configured to control the dimming level of the display module to be equal to or less than the first unsuitable brightness. Wherein, the first unsuitable brightness is based on the expression Ld1=α×La1 β The calculation is performed using the first equation, where La1 is the first adaptive luminance, Ld1 is the first unsuitable luminance, α is the first coefficient, and β is the second coefficient.

2. The head-mounted display device as claimed in claim 1, wherein, The first adaptive brightness of the first image is based on 5 ° The perspective is calculated using the white peak of a low-pass filter.

3. The head-mounted display device as described in claim 2, wherein, The first coefficient α is 17.2 ± 0.17, and the second coefficient β is 0.417 ± 0.

041.

4. The head-mounted display device as claimed in claim 1, wherein, The calculator also includes: A frame comparator configured to determine whether a second image different from the first image has been received.

5. The head-mounted display device as claimed in claim 4, wherein, The calculator scans the second image based on the predetermined viewing angle and calculates the second adaptive brightness of the second image.

6. The head-mounted display device as claimed in claim 5, wherein, The second adaptive brightness of the second image is based on 5 ° The perspective is calculated using the white peak of a low-pass filter.

7. The head-mounted display device as claimed in claim 5, wherein, The uncomfortable brightness calculator is further configured to calculate the second uncomfortable brightness based on the second adapted brightness, and The calculator also includes: An unsuitable brightness change determiner is configured to determine, based on predetermined conditions, to change the first unsuitable brightness to the second unsuitable brightness.

8. The head-mounted display device as claimed in claim 7, wherein, The predetermined conditions include: The second adaptive brightness changes by 20% or more compared to the first adaptive brightness; and The altered second adaptive brightness is maintained for 2 seconds or longer.

9. The head-mounted display device as claimed in claim 7, wherein, The second unsuitable brightness is based on the expression Ld2=α×La2 β The second equation is used to calculate, and Wherein, La2 is the second adaptive luminance, Ld2 is the second unsuitable luminance, α is 17.2±0.17, and β is 0.417±0.

041.

10. The head-mounted display device as claimed in claim 7, wherein, The brightness controller adjusts the dimming level of the display module to be less than or equal to the second unsuitable brightness based on the change from the first unsuitable brightness to the second unsuitable brightness.

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