Wearable display device

Abstract

The application relates to a wearable display device, comprising a backlight module, a display driving chip, a power supply module and a main control module. The backlight driving chip of the backlight module comprises a switching circuit and a voltage regulating circuit, two ends of the switching circuit are connected with the voltage regulating circuit and a light emitting array of the backlight module respectively; the display driving chip outputs a first control signal to the switching circuit; the power supply module comprises a charging interface and a detection unit; the charging interface transmits a power supply current output by an external power supply; the detection unit outputs a detection signal corresponding to the power supply current; the main control module receives the detection signal and outputs a second control signal with a second duty cycle according to the detection signal; the voltage regulating circuit adjusts the power supply voltage to a target voltage positively correlated with the second duty cycle under the control of the second control signal; the switching circuit periodically turns on and off a power supply path between the voltage regulating circuit and the light emitting array under the control of the first control signal; the light emitting array emits light under the drive of the target voltage.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to wearable display devices. Background Technology

[0002] With the rapid development of Virtual Reality (VR) and Augmented Reality (AR) technologies, wearable display devices (HMDs) are gradually becoming an important tool for immersive experiences.

[0003] Currently, wearable display devices face a key trade-off in their design: in order to reduce the weight of the device and improve wearing comfort and user experience, most devices choose not to have a built-in battery and instead rely on an external power source.

[0004] However, the power supply current directly output by the external power supply cannot be adapted to the wearable display device, causing the wearable display device to malfunction. Utility Model Content

[0005] Therefore, it is necessary to provide a wearable display device to address the aforementioned problem of incompatibility between wearable display devices and external power supplies.

[0006] In a first aspect, this application provides a wearable display device, comprising:

[0007] A backlight module includes a backlight driver chip and a light-emitting array. The backlight driver chip includes a switching circuit and a voltage regulation circuit. The two ends of the switching circuit are respectively connected to the voltage regulation circuit and the light-emitting array.

[0008] The display driver chip is connected to the switching circuit and outputs a first control signal with a first duty cycle to the switching circuit; the first duty cycle is associated with the brightness level.

[0009] The power supply module includes a charging interface and a detection unit;

[0010] The charging interface is used to connect to an external power source and to transmit the power supply current output by the external power source.

[0011] The detection unit is connected to the charging interface and is used to output a detection signal corresponding to the power supply current.

[0012] The main control module is connected to the voltage regulation circuit and the detection unit. The main control module is used to receive the detection signal and output a second control signal with a second duty cycle according to the detection signal; the second duty cycle is negatively correlated with the power supply current.

[0013] The back voltage regulation circuit is used to connect to the power supply voltage and, under the control of the second control signal, adjusts the power supply voltage to a target voltage that is positively correlated with the second duty cycle; the switching circuit, under the control of the first control signal, periodically turns on and off the power supply path between the voltage regulation circuit and the light-emitting array.

[0014] The light-emitting array emits light under the drive of the target voltage.

[0015] Beneficial Effects: The main control module is connected to both the backlight driver chip and the detection unit, receiving detection signals. Therefore, it can adjust the duty cycle of the second control signal based on the detection signals. The supply current and the second duty cycle are negatively correlated. For example, if the detection signal indicates a larger supply current, the second duty cycle is reduced to prevent the wearable display device's load current from exceeding the safe current threshold, thus preventing malfunction. Conversely, if the detection signal indicates a smaller supply current, the duty cycle of the second control signal is increased to prevent insufficient power supply from preventing the backlight driver chip from driving the light-emitting elements to the target brightness, thus affecting the display effect. The backlight driver chip uses the first control signal to control the switching circuit to turn on or off the power supply path between the voltage regulation circuit and the light-emitting array. The first duty cycle affects the conduction time of the power supply path, the time it takes for the target voltage to be transmitted to the light-emitting array, and thus the light-emitting time of each light-emitting element in the array. The second control signal controls the voltage regulation operation of the voltage regulation circuit. The second duty cycle affects the target voltage, thus affecting the brightness of the light-emitting elements during the power supply path's conduction period. Therefore, the brightness of the light-emitting element is controlled by the first duty cycle of the first control signal and the second duty cycle of the second control signal, avoiding the limitations of single-parameter adjustment. For example, adjusting only the duty cycle may lead to flickering or color deviation, allowing the backlight driver chip to cover a wider range of brightness adjustment, such as from an extremely dark night mode to a bright outdoor mode, improving the display effect. Furthermore, the first duty cycle is determined according to the brightness level selected by the user, ensuring that the final brightness displayed by the light-emitting array conforms to the user's own visual characteristics (such as myopia degree, pupil light reflection speed) and usage habits, guaranteeing the consistency of the user's subjective brightness perception, and enabling the wearable display device to adapt to individual visual differences. The brightness of the light-emitting element is controlled by the first duty cycle of the first control signal and the second duty cycle of the second control signal, which can reduce the computational power consumption caused by image analysis of the image to be displayed. In addition, by not introducing the brightness information of the image itself, it can also reduce the interference of image content with brightness control, which can lead to unstable images and reduce the flickering of the image due to changes in the brightness of the image itself, thus reducing dizziness and visual fatigue.

[0016] In one embodiment, the detection unit includes:

[0017] A sampling resistor, the first end of which is connected to the charging interface, is used to convert the supply current into the corresponding supply voltage;

[0018] A differential amplifier is provided, wherein the non-inverting input terminal of the differential amplifier is connected to the first terminal of the sampling resistor, the inverting input terminal of the differential amplifier is connected to the second terminal of the sampling resistor, and the output terminal of the differential amplifier is connected to the main control module, for outputting the detection signal corresponding to the supply voltage to the main control module.

[0019] Beneficial effects: The voltage difference across the sampling resistor is input to a differential amplifier. After the differential amplifier gains a gain of G, it outputs a detection signal to the main control module. The differential amplifier suppresses electromagnetic interference, power fluctuations, and other noise during signal transmission, while amplifying the actual supply current information and outputting it to the main control module. This allows the main control module to determine the voltage based on the voltage across the sampling resistor. R =I×R to inversely calculate the supply current I, where R is the resistance value of the sampling resistor. This improves the sampling accuracy, enabling the main control module to obtain more accurate supply current information and output a more precise second control signal based on this, thereby achieving accurate adjustment of the brightness of the light-emitting element and improving the display effect of the wearable display device.

[0020] In one embodiment, the wearable display device further includes:

[0021] A charging chip is configured with a charging protocol corresponding to the charging interface. The charging chip is connected to the second end of the sampling resistor to receive the supply voltage and convert the supply voltage into a system voltage based on the charging protocol.

[0022] A power management chip, connected to the charging chip and the main control module, is used to receive the system voltage, convert the system voltage, and then supply power to the main control module.

[0023] Beneficial effects: The charging chip converts the supply voltage into the system voltage based on this charging protocol, thereby dynamically adjusting the system voltage and achieving power management. By managing the system voltage through a power management chip, the normal operation of wearable display devices is ensured.

[0024] In one embodiment, the power supply module further includes:

[0025] A step-down unit is connected to the second terminal of the sampling resistor and the charging chip respectively, so as to output a preset voltage to the charging chip;

[0026] When the charging chip receives the preset voltage, it outputs the system voltage.

[0027] Beneficial effects: The power supply voltage is directly related to the external power source and is generally a relatively high voltage. Therefore, in this embodiment, the power supply voltage is reduced to a preset voltage by a step-down unit, so that the charging chip can accurately identify the presence of the external power source.

[0028] In one embodiment, the first control signal includes a first signal and a second signal; the second control signal includes a third signal and a fourth signal;

[0029] The number of backlight modules is two, namely a first backlight module and a second backlight module. The first backlight module is used to provide a display image to a first eye, and the second backlight module is used to provide a display image to a second eye.

[0030] The voltage regulation circuit in the first backlight module is connected to the second end of the sampling resistor and is used to drive the light-emitting array to emit light under the power supply voltage according to the first signal and the third signal.

[0031] The voltage regulation circuit of the second backlight module is connected to the second terminal of the sampling resistor, and is used to drive the light-emitting array to emit light under the power supply voltage according to the second signal and the fourth signal. Beneficial effects: There are two backlight modules. The first backlight module and the second backlight module provide display images to the first and second viewing eyes respectively. The display images provided to the first and second viewing eyes can be the same or different. Users view images through independent displays for both eyes, improving the display experience. The voltage regulation circuits in both the first and second backlight modules are connected to the second terminal of the sampling resistor, thus enabling them to operate under the power supply voltage without the need for additional voltage conversion circuits, reducing the number of voltage conversions and improving power efficiency.

[0032] In one embodiment, the display driver chip includes:

[0033] The first driver chip is connected to the switching circuit in the first backlight module and is used to output the first signal to the switching circuit in the first backlight module.

[0034] The second driver chip is connected to the switching circuit in the second backlight module and is used to output the second signal to the switching circuit in the backlight module; the timing of the second signal is the opposite of the timing of the first signal.

[0035] Beneficial effects: The first driver chip and the second driver chip independently provide corresponding first and second signals to the switching circuits in the first and second backlight modules, respectively, to achieve independent driving of the backlight driver chip. The timing of the first and second signals is opposite, so the switching circuits in the first and second backlight modules can control the light-emitting elements in the light-emitting arrays in the first and second backlight modules to emit light in staggered time, thereby reducing the total load current of the wearable display device. This reduces the situation where the total load current of the system is too large due to the dynamic change of the load during the power-on process caused by the light-emitting array following the brightness level, which exceeds the safe current value and causes the wearable display device to repeatedly restart and fail to work normally, thus improving the stability of the wearable display device.

[0036] In one embodiment, the main control module includes:

[0037] An analog-to-digital converter, connected to the output of the differential amplifier, is used to convert the detection signal in analog form into the detection signal in digital form before outputting it.

[0038] The controller, connected to the analog-to-digital converter and the backlight driver chip, is used to receive the detection signal in digital signal form and output the second control signal with a duty cycle corresponding to the detection signal.

[0039] Beneficial effects: After the analog signal is converted into a digital signal by the analog converter, the controller can accurately identify the detection signal and respond to it by outputting a second control signal with the corresponding duty cycle based on the internal preset control program.

[0040] In one embodiment, the differential amplifier gain G satisfies:

[0041] Imin×R1×G≥0.5Vadc and Imax0×R1×G≤Vadc;

[0042] Wherein, Imin is the preset current adjustment threshold; R1 is the resistance value of the sampling resistor; Vadc is the operating voltage of the analog-to-digital converter; and Imax0 is the preset maximum load current.

[0043] Beneficial effects: Setting the differential amplifier gain G to satisfy: Imin×R1×G≥0.5Vadc and Imax0×R1×G≤Vadc ensures that the detection signal is within the dynamic range of the analog-to-digital converter of the main control module, improves the signal-to-noise ratio of the detection signal, prevents signal oversaturation, and ensures that the analog-to-digital converter can accurately convert the detection signal in analog form.

[0044] In one embodiment,

[0045] The main control module is connected to the display driver chip and is used to receive the first control signal and detect the level of the first control signal. When the first control signal is low, the module outputs a duty cycle adjusted to the second control signal corresponding to the detection signal.

[0046] Beneficial effects: When the first control signal is detected to be low, the switching of the second control signal is triggered, thereby outputting the second control signal after adjusting the duty cycle to the backlight driver chip, thereby reducing brightness jitter and improving the display stability of the display screen.

[0047] In one embodiment, the power supply module includes:

[0048] A filtering unit is connected to both the charging interface and the detection unit to filter out the AC component in the power supply current.

[0049] Beneficial effects: The filter unit can filter out the AC component in the power supply current, improving the stability of the power supply current. Furthermore, it prevents excessive impedance in the power supply interface cable from causing a drop in power supply voltage and affecting the normal power supply to the system. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is one of the structural schematic diagrams of a wearable display device according to an embodiment of this application;

[0052] Figure 2 This is a schematic diagram of the backlight driver chip in one embodiment of this application;

[0053] Figure 3 This is a schematic diagram of the detection unit in one embodiment of this application;

[0054] Figure 4 This is a second schematic diagram of the structure of a wearable display device according to an embodiment of this application;

[0055] Figure 5 This is one of the structural schematic diagrams of the power supply module in one embodiment of this application;

[0056] Figure 6 This is a schematic diagram of the backlight module in one embodiment of this application;

[0057] Figure 7This is a schematic diagram of the structure of a display driver chip in one embodiment of this application;

[0058] Figure 8 This is one of the curves showing the change of the total system load current over time in a wearable display device according to an embodiment of this application;

[0059] Figure 9 This is the second curve showing the change of the total system load current over time in a wearable display device according to one embodiment of this application;

[0060] Figure 10 This is a schematic diagram of the main control module in one embodiment of this application;

[0061] Figure 11 This is a third schematic diagram of the structure of a wearable display device according to one embodiment of this application;

[0062] Figure 12 This is a second schematic diagram of the power supply module in one embodiment of this application.

[0063] Explanation of icon numbers:

[0064] 110: Backlight module; 111: Backlight driver chip; 1111: Switching circuit; 1112: Voltage regulation circuit; 112: Light emission array; 113: First backlight module; 114: Second backlight module; 120: Display driver chip; 121: First driver chip; 122: Second driver chip; 130: Power supply module; 131: Charging interface; 132: Detection unit; 1321: Sampling resistor; 1322: Differential amplifier; 133: Charging chip; 134: Power management chip; 135: Buck unit; 136: Filtering unit; 140: Main control module; 141: Analog-to-digital converter; 142: Controller; 200: External power supply. Detailed Implementation

[0065] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0066] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0067] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0068] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0069] The wearable display device provided in this application can be any head-mounted device with display function. For example, the wearable display device can be an AR device, a VR device, or a VR / MR (Mixed Reality) all-in-one device, and is not limited thereto.

[0070] In related technologies, VR / MR terminals mainly include two product forms: VR / MR all-in-one devices and VR / MR standalone devices. VR / MR all-in-one devices house the complex spatial positioning and graphics rendering computing center within the device itself. Their high power consumption requires a battery capacity of at least 5000mAh for a 2-hour battery life, increasing the overall battery compartment weight by more than 100g. The disadvantage is that the weight leads to discomfort when worn. VR / MR standalone devices are typically powered by a PC or an external power source via a USB cable. Data from sensors on the wearable display device is transmitted to the PC (Personal Computer) via USB data stream. The PC's powerful computing center capabilities are used for spatial positioning and graphics rendering. The advantage is that wearable display devices do not have a complex SoC (System on Chip) computing center chip, eliminating the need for complex heat dissipation and battery compartment designs. They are lightweight, comfortable to wear, and have strong computing power. The disadvantages are latency and the inability to escape the constraints of a PC. So, battery-free VR / MR all-in-one devices, falling somewhere in between, have advantages in weight due to the absence of a battery compartment, and the computing center can be completed locally. However, VR / MR all-in-one devices are difficult to adapt to mainstream external power supplies of 200V, such as power banks, charging adapters, and power signals from USB ports. Most power banks and adapters typically have a load capacity of 2.4~3A when operating at 5V. VR all-in-one devices often experience transient peaks of up to 14W during startup, making it easy to encounter situations where they fail to power on or repeatedly restart.

[0071] To address the aforementioned technical problems, this application provides a wearable display device. (See attached document.) Figure 1 and attached Figure 2 , attached Figure 1 This application shows one of the structural schematic diagrams of a wearable display device according to an embodiment of the present application. Figure 2 A schematic diagram of the backlight driver chip 111 is shown. The wearable display device provided in this application may include a backlight module 110, including a backlight driver chip 111 and a light-emitting array 112. The backlight driver chip 111 includes a switching circuit 1111 and a voltage regulating circuit 1112. The two ends of the switching circuit 1111 are respectively connected to the voltage regulating circuit 1112 and the light-emitting array 112.

[0072] The wearable display device provided in this application may include a display driver chip 120, which is connected to a switching circuit 1111 and outputs a first control signal PWM_LCD with a first duty cycle to the switching circuit 1111.

[0073] The first duty cycle is associated with the brightness level. For example, the main control module 140 obtains the corresponding target display brightness information according to the user-preset brightness level, and generates a signal carrying the first duty cycle information according to the target display brightness information. The main control module 140 can be connected to the display driver chip 120. The main control module 140 sends the signal carrying the first duty cycle information to the display driver chip 120, so that the display driver chip 120 converts the signal carrying the first duty cycle information into a first control signal with the first duty cycle that can be recognized by the switching circuit 1111.

[0074] The switching circuit 1111 may include a controlled switch. The controlled terminal of the controlled switch is connected to the display driver chip 120 to receive a first control signal. The two conducting terminals of the controlled switch are respectively connected to the voltage regulating circuit 1112 and the light-emitting array 112. The conduction and deactivation of the controlled switch are controlled by the first control signal. When the first control signal is at a first level, the controlled switch is turned on, and the switching element receives the target voltage and emits light. When the first control signal is at a second level, the controlled switch is turned off. By changing the first duty cycle of the first control signal, the illumination time of the light-emitting element in one cycle (one cycle includes one first level state and one second level state) can be changed, thereby realizing the brightness adjustment of the light-emitting element.

[0075] The voltage regulating circuit 1112 can be any circuit capable of voltage conversion based on the duty cycle of a control signal. For example, the voltage regulating circuit 1112 may include a chopper voltage regulating sub-circuit. This sub-circuit changes the average value of the output voltage using pulse width modulation (PWM) through the high-frequency switching of the switching device. The duty cycle (D, i.e., the ratio of the switching on time to the period) determines the magnitude of the output voltage. Therefore, by adjusting the second duty cycle of the second control signal, the magnitude of the target voltage can be adjusted, thereby adjusting the brightness of the light-emitting element. For example, the voltage regulating circuit 1112 may include a buck-boost chopper sub-circuit, but is not limited thereto.

[0076] The wearable display device provided in this application may include a power supply module 130, which may include a charging interface 131 and a detection unit 132. The charging interface 131 is used to connect to an external power supply 200 and to transmit the power supply current output by the external power supply 200; the detection unit 132 is connected to the charging interface 131 and is used to output a detection signal Vsample corresponding to the power supply current.

[0077] The wearable display device provided in this application may include a main control module 140, which is connected to a voltage regulation circuit 1112 and a detection unit 132. The main control module 140 is used to receive a detection signal Vsample and output a second control signal PWM_CPU with a second duty cycle according to the detection signal Vsample. The power supply current is negatively correlated with the duty cycle of the second control signal PWM_CPU.

[0078] The voltage regulating circuit 1112 is used to connect to the power supply voltage VBUS and, under the control of the second control signal PWM_CPU, adjusts the power supply voltage VBUS to a target voltage that is positively correlated with the second duty cycle; the switching circuit 1111 periodically turns on and off the power supply path between the voltage regulating circuit 1112 and the light-emitting array 112 under the control of the first control signal PWM_LCD; the light-emitting array 112 emits light under the drive of the target voltage.

[0079] In this context, both the first control signal PWM_LCD and the second control signal PWM_CPU can be pulse width modulation signals.

[0080] In large-screen display brightness control, the backlight module is typically divided into multiple independently controlled areas (such as hundreds to thousands of zones). Each zone independently adjusts its backlight brightness based on the image brightness signal of its corresponding area, reducing light leakage and improving image contrast through local dimming. The image brightness signal is generated by analyzing the image content to be displayed using algorithms, such as brightness histograms and average regional brightness values. However, in wearable display devices, the optical path is near the eye, and the brightness differences between backlight zones are "averaged out." Light leakage in dark areas may actually be more noticeable due to light path refraction. When the human eye observes at close range, it is more sensitive to uneven local brightness (such as halo effects at the edges of zones), which may lead to a sense of image fragmentation and a poor visual experience. Furthermore, backlight zones require complex driving circuits and algorithms (such as dynamic dimming algorithms). The backlight adjustment speed is usually slower than the pixel response speed, thus increasing display latency and potentially causing image ghosting or dizziness. The local brightness changes of the backlight zones may be out of sync with fast-moving scenes (such as scene transitions when turning one's head), leading to visual confusion. The backlight module is small in size. Due to this small size, forcibly dividing the backlight into zones may result in excessively high density of light-emitting elements, making it difficult to integrate the driving circuit and physically achieve independent light control. In this embodiment, the display brightness of each light-emitting element in the light-emitting array 112 is controlled by the first duty cycle of the first control signal PWM_LCD and the second duty cycle of the second control signal PWM_CPU. The first duty cycle is related to the brightness level selected by the user, ensuring that the final brightness displayed by the light-emitting array conforms to the user's own visual characteristics (such as myopia degree and pupil light reflection speed) and usage habits, guaranteeing the consistency of the user's subjective brightness perception, and enabling the wearable display device to adapt to individual visual differences. The light emission brightness of the light-emitting elements is controlled by the first duty cycle of the first control signal and the second duty cycle of the second control signal, which can reduce the computational power consumption caused by image analysis of the image to be displayed. In addition, by not introducing the brightness information of the image itself, it can also reduce the image content from interfering with brightness control, thus reducing screen instability and dizziness caused by changes in the brightness of the image itself.

[0081] The number of backlight modules 110 and display driver chips 120 can be flexibly set according to display requirements. For example, the wearable display device in this embodiment is used to provide a display image to the human eye, and typically separate displays are provided for the left and right eyes. The number of backlight modules 110 and display driver chips 120 can be two, to provide display images to the left and right eyes respectively. This is not a limitation.

[0082] The charging interface 131 can be any interface capable of transmitting voltage and current. For example, the charging interface 131 can be a USB interface, but it is not limited to this.

[0083] The detection unit 132 detects the power supply current output by the external power supply 200 and outputs a corresponding detection signal Vsample. The detection signal Vsample can characterize the power supply capability of the external power supply 200 and the system current of the wearable display device.

[0084] The main control module 140 can be a microcomputer such as a CPU (Center Processing Unit) capable of program execution and data processing.

[0085] Backlight current I LED =D×V FB / R FB D is the emission time ratio of the light-emitting array 112, V FB R provides a feedback voltage to the light-emitting array 112 for the backlight driver chip 111. FB A feedback resistor is placed between the LED array 112 and the equivalent ground terminal to stabilize the circuit output. The input current I of the LED array 112... BL =I LED ×V LED / ηV BUS V LED Where η is the forward voltage of the light-emitting element, and η is the conversion efficiency of the external power supply 200. The total system load current Imax = Isys + I BL Isys represents the current consumption of the components in the wearable display device other than the light-emitting array 112. Therefore, Imax = Isys + K * D, where K = V. FB *V LED / R FB / η / V BUS As can be seen, the total load current of the system increases linearly with the increase of D. Therefore, by adjusting the duty cycle of the second control signal PWM_CPU to correspond with the detection signal Vsample, the magnitude of the total load current of the system and the luminous brightness of each light-emitting element can be adaptively balanced.

[0086] For example, if Imax0 = 2.3A and Imin = 1.9A, when the supply current reflected by the detection signal Vsample (i.e., the total system current of the wearable display device at this time) is less than or equal to 1.9A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 100% to ensure the brightness of the light-emitting element. When the supply current reflected by the detection signal Vsample (i.e., the total system current of the wearable display device at this time) is greater than 2.3A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 50% to avoid excessive total system load current causing abnormal operation of the wearable display device. The adjustment logic of the main control module 140 in adjusting the duty cycle of the second control signal PWM_CPU to match the detection signal Vsample can be flexibly set as needed, as long as the duty cycle of the second control signal PWM_CPU is negatively correlated with the supply current represented by the detection signal Vsample.

[0087] For example, to reduce brightness fluctuations caused by large brightness changes during duty cycle adjustment, the duty cycle adjustment is divided into multiple levels. For instance, it can be divided into ten levels: Imax0 = 2.3A, Imin = 1.9A, I... BL =1.2A (D=100%), (2.3-1.9) / 10=40mA, preset I for each gear. BLIf the total Itotal for each gear is 1.5 times, and the current is 60mA, then the duty cycle difference between the two gears is 5%. When the supply current is less than or equal to 1.9A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 100%; when the supply current is 1.9A~1.94A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 95%; when the supply current is 1.94A~1.98A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 90%; when the supply current is 1.98A~2.02A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 85%; when the supply current is 2.02A~2.06A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 80%; when the supply current is 2.06A~2.1A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 5%. The main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 75% when the supply current is 2.1A~2.14A; when the supply current is 2.14A~2.18A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 65%; when the supply current is 2.18A~2.22A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 60%; when the supply current is 2.22A~2.26A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 55%; when the supply current is 2.26A~2.3A, or when the supply current is greater than 2.3A, the main control module 140 outputs a second control signal PWM_CPU with a duty cycle of 50%. In other embodiments, the main control module 140 may adjust the duty cycle of the second control signal PWM_CPU to the adjustment logic of the detection signal Vsample, but is not limited to this.

[0088] In this embodiment, the main control module 140 is connected to the backlight driver chip 111 and the detection unit 132 respectively, and receives the detection signal Vsample. Therefore, it can adjust the duty cycle of the second control signal PWM_CPU according to the detection signal Vsample. The supply current and the duty cycle of the second control signal PWM_CPU are negatively correlated. For example, if the detection signal Vsample represents a larger supply current, the duty cycle of the second control signal PWM_CPU is reduced to avoid the load current of the wearable display device exceeding the safety threshold when the supply current is large, causing the wearable display device to malfunction. Conversely, if the detection signal Vsample represents a smaller supply current, the duty cycle of the second control signal PWM_CPU is increased to avoid the backlight driver chip 111 being unable to drive the brightness of the light-emitting element to the target brightness due to insufficient power supply, thus affecting the display effect.

[0089] The backlight driver chip 111 uses a first control signal to control the power supply path between the switching circuit 1111 and the voltage regulation circuit 1112 and the light-emitting array 112. The first duty cycle affects the conduction time of the power supply path, which in turn affects the duration of the target voltage transmission to the light-emitting array 112, and thus affects the light-emitting duration of each light-emitting element in the light-emitting array 112. The second control signal controls the voltage regulation operation of the voltage regulation circuit 1112. The second duty cycle affects the magnitude of the target voltage, which in turn affects the brightness of the light-emitting elements during the conduction of the power supply path. Therefore, the brightness of the light-emitting elements is controlled by the first duty cycle of the first control signal and the second duty cycle of the second control signal, avoiding the limitations of single parameter adjustment. For example, adjusting only by the duty cycle may lead to flickering or color deviation, allowing the backlight driver chip 111 to cover a wider brightness adjustment range, such as from an extremely dark night mode to a high-brightness outdoor mode, thus improving the display effect.

[0090] See appendix Figure 3 , attached Figure 3 A schematic diagram of the detection unit 132 in one embodiment of this application is shown. In one embodiment, the detection unit 132 may include a sampling resistor 1321 and a differential amplifier 1322.

[0091] The first end of the sampling resistor 1321 is connected to the charging interface 131. The sampling resistor 1321 is used to convert the supply current into the corresponding supply voltage VBUS.

[0092] The non-inverting input of the differential amplifier 1322 is connected to the first terminal of the sampling resistor 1321, the inverting input of the differential amplifier 1322 is connected to the second terminal of the sampling resistor 1321, and the output of the differential amplifier 1322 is connected to the main control module 140 to output a detection signal Vsample corresponding to the power supply voltage VBUS to the main control module 140.

[0093] The sampling resistor 1321 can be a small-value, high-precision resistor. For example, the accuracy of the sampling resistor 1321 can be greater than or equal to 1%, and the resistance value of the sampling resistor 1321 can be less than or equal to 0.01 ohms, but is not limited thereto.

[0094] In this embodiment, the voltage difference across the sampling resistor 1321 is input to the differential amplifier 1322. After the differential amplifier 1322 gains a gain of G, it outputs a detection signal Vsample to the main control module 140. The differential amplifier 1322 is used to suppress electromagnetic interference, power fluctuations, and other noise during signal transmission, while amplifying the actual current information of the power supply current and outputting it to the main control module 140. This allows the main control module 140 to detect the voltage difference based on the voltage Vsample. R =I×R to inversely calculate the supply current I, where R is the resistance value of the sampling resistor 1321, which improves the sampling accuracy, enabling the main control module 140 to obtain more accurate supply current information, and based on this, output a more precise second control signal PWM_CPU to achieve accurate adjustment of the brightness of the light-emitting element and improve the display effect of the wearable display device.

[0095] See appendix Figure 4 , attached Figure 4 A second schematic diagram of a wearable display device according to an embodiment of this application is shown. In one embodiment, the wearable display device further includes a charging chip 133 and a power management chip 134.

[0096] The charging chip 133 is configured with a charging protocol corresponding to the charging interface 131. The charging chip 133 is connected to the second end of the sampling resistor 1321 to receive the supply voltage VBUS and convert the supply voltage VBUS into the system voltage Vsys based on the charging protocol. The power management chip 134 is connected to the charging chip 133 and the main control module 140 to receive the system voltage Vsys and convert the system voltage Vsys before supplying power to the main control module 140.

[0097] The charging protocol allows the external power supply 200 to exchange information with the charging chip 133 through the charging interface 131, communicating via data lines (such as D+ and D- lines) or specific pins (such as CC1 and CC2). The charging chip 133 is configured with a charging protocol corresponding to the charging interface 131, thus enabling the charging chip 133 to interact with the external power supply 200 through the charging interface 131 and obtain power supply information from the external power supply 200, such as the power level. For example, the charging interface 131 can be a USB interface, and the charging chip 133 can be a USB charging chip 133, which can be configured with the USB PD (Power Delivery) charging protocol. It is not limited to this.

[0098] In this embodiment, the charging chip 133 converts the supply voltage VBUS into the system voltage Vsys based on the charging protocol, thereby dynamically adjusting the size of the system voltage Vsys to achieve power management. The system voltage Vsys can be understood as the voltage that supports the normal operation of the entire wearable display device system.

[0099] The power management integrated circuit (PMIC) 134 enables power management of the system voltage Vsys. For example, the PMIC 134 may include a boost module, a buck module, a buck-boost module, a linear regulator, a switching regulator, a current protection circuit, a current distribution circuit, a timing controller, a voltage detection circuit, a current detection circuit, a temperature detection circuit, etc., and can perform buck-boost conversion, buck-boost conversion, voltage distribution, current distribution, etc., on the system voltage Vsys to ensure the normal operation of the wearable display device.

[0100] See appendix Figure 5 , attached Figure 5 This diagram illustrates one of the structural schematics of a power supply module 130 according to an embodiment of this application. In one embodiment, the power supply module 130 includes a step-down unit 135, which is connected to the second terminal of a sampling resistor 1321 and a charging chip 133 to output a preset voltage VBAT to the charging chip 133.

[0101] Among them, the charging chip 133 outputs the system voltage Vsys when it receives the preset voltage VBAT.

[0102] The preset voltage VBAT is a pre-configured voltage used to characterize the presence of the external power supply 200. For example, the preset voltage VBAT can be 3.3V. The supply voltage VBUS is directly related to the external power supply 200 and is generally a higher voltage. Therefore, in this embodiment, the supply voltage VBUS is stepped down to the preset voltage VBAT by the step-down unit 135, so that the charging chip 133 can accurately identify the presence of the external power supply 200.

[0103] Charging chip 133 can convert the supply voltage VBUS or the preset voltage VBAT into the system voltage Vsys.

[0104] In some embodiments, the system voltage Vsys does not need to be greater than the preset voltage VBAT, in which case the charging chip 133 can directly convert the preset voltage VBAT into the system voltage Vsys. However, in some embodiments, the system voltage Vsys is greater than the preset voltage VBAT, and the preset voltage VBAT is insufficient to support the conversion of the system voltage Vsys. Therefore, the charging chip 133 can convert the supply voltage VBUS into the system voltage Vsys to meet the power demand.

[0105] See appendix Figure 6 , attached Figure 6 A schematic diagram of the backlight module 110 according to one embodiment of this application is shown. In one embodiment, the first control signal PWM_LCD includes a first signal PWM1_LCD and a second signal PWM2_LCD; the second control signal PWM_CPU includes a third signal PWM1_CPU and a fourth signal PWM2_CPU. The number of backlight modules 110 is two, for example, the two backlight modules 110 are a first backlight module 113 and a second backlight module 114.

[0106] The first backlight module 113 is used to provide a display image to the first eye, and the second backlight module 114 is used to provide a display image to the second eye.

[0107] The voltage regulation circuit of the first backlight module 113 is connected to the second end of the sampling resistor 1321, and is used to drive each light-emitting element in the light-emitting array 112 to emit light under the power supply voltage VBUS according to the first signal PWM1_LCD and the third signal PWM1_CPU.

[0108] The voltage regulation circuit of the second backlight module 114 is connected to the second end of the sampling resistor 1321, and is used to drive each light-emitting element in the light-emitting array 112 to emit light according to the second signal PWM2_LCD and the fourth signal PWM2_CPU, under the power supply voltage VBUS.

[0109] In this embodiment, there are two backlight modules 110. The first backlight module 113 and the second backlight module 114 provide display images to the first and second viewing eyes, respectively. The display images provided to the first and second viewing eyes can be the same or different. Users view images through independent displays for both eyes, improving the display experience. The voltage regulation circuits in both the first and second backlight modules 113 and 114 are connected to the second terminal of the sampling resistor, thus enabling them to operate under the power supply voltage VBUS without the need for additional voltage conversion circuits, reducing the number of voltage conversions and improving power efficiency.

[0110] See appendix Figure 7 , attached Figure 7 A schematic diagram of the structure of a display driver chip 120 according to one embodiment of this application is shown. In one embodiment, the display driver chip 120 includes a first driver chip 121 and a second driver chip 122.

[0111] The first driver chip 121 is connected to the switching circuit in the first backlight module 113 and is used to output a first signal PWM1_LCD to the switching circuit in the first backlight module 113. The second driver chip 122 is connected to the switching circuit in the second backlight module 114 and is used to output a second signal PWM2_LCD to the switching circuit in the second backlight module 114.

[0112] The timing of the second signal PWM2_LCD is the reverse of the timing of the first signal PWM1_LCD, and the first signal PWM1_LCD and the second signal PWM2_LCD are complementary in time. For example, when the first signal PWM1_LCD is high, the second signal PWM2_LCD is low, and when the first signal PWM1_LCD is low, the second signal PWM2_LCD is high.

[0113] In this embodiment, the first driving chip 121 and the second driving chip 122 independently provide corresponding first signals PWM1_LCD and second signals PWM2_LCD to the switching circuits in the first backlight module 113 and the second backlight module 114, respectively, to achieve independent driving of the backlight driving chip 111. The timing of the first signals PWM1_LCD and the second signals PWM2_LCD is opposite. Therefore, the switching circuits in the first backlight module 113 and the second backlight module 114 can control the light-emitting elements in the light-emitting array 112 in the first backlight module 113 and the second backlight module 114 to emit light at staggered times. This reduces the total load current of the wearable display device and reduces the situation where the total load current of the system is too large due to the dynamic load change during the power-on process caused by the light-emitting array 112 following the display frame rate, exceeding the safe current value and causing the wearable display device to repeatedly restart and fail to work normally. This improves the stability of the wearable display device.

[0114] For example, see Appendix Figure 8 , attached Figure 8 One of the curves showing the change of the total system load current over time in a wearable display device according to an embodiment of this application is shown. Since the timing of the first signal PWM1_LCD and the second signal PWM2_LCD is opposite, the light-emitting arrays 112 in the first backlight module 113 and the second backlight module 114 emit light at different times. Therefore, the input current I1 of the light-emitting array 112 in the first backlight module 113 and the input current I2 of the light-emitting array 112 in the second backlight module 114 will not be superimposed. At this time, the total system load current Imax1 is less than the safe current value, which improves the stability of the wearable display device.

[0115] Another example is shown in the appendix. Figure 9 , attached Figure 9The second curve of the total system load current changing with time in the wearable display device in the embodiment of this application is shown. When the main control module 140 adjusts the duty cycle of the second control signal PWM_CPU to correspond to the power supply current, Imax2 is less than Imax1, which further reduces the total system load current and improves the stability of the wearable display device.

[0116] See appendix Figure 10 , attached Figure 10 A schematic diagram of the main control module 140 according to one embodiment of this application is shown. In one embodiment, the main control module 140 may include an analog-to-digital converter 141 and a controller 142.

[0117] The analog-to-digital converter 141 is connected to the output of the differential amplifier 1322 and is used to convert the analog signal detection signal Vsample into a digital signal detection signal Vsample before outputting it. The controller 142 is connected to the analog-to-digital converter 141 and the backlight driver chip 111 and is used to receive the digital signal detection signal Vsample and output a second control signal PWM_CPU with a duty cycle corresponding to the detection signal Vsample.

[0118] In this embodiment, the analog signal detection signal Vsample is converted into a digital signal detection signal Vsample by an analog converter and then output, so that the controller 142 can accurately identify the detection signal Vsample and respond to the detection signal Vsample by outputting a second control signal PWM_CPU with a corresponding duty cycle based on the internally preset control program.

[0119] In one embodiment, the gain G of the differential amplifier 1322 satisfies:

[0120] Imin×R1×G≥0.5Vadc and Imax0×R1×G≤Vadc;

[0121] Where Imin is the preset current regulation threshold; R1 is the resistance value of the sampling resistor 1321; Vadc is the operating voltage of the analog-to-digital converter 141; and Imax0 is the preset maximum load current.

[0122] In this embodiment, the gain G of the differential amplifier 1322 is set to satisfy: Imin×R1×G≥0.5Vadc and Imax0×R1×G≤Vadc, to ensure that the detection signal Vsample is within the dynamic range of the analog-to-digital converter 141 of the main control module 140, thereby improving the signal-to-noise ratio of the detection signal Vsample, preventing signal over-saturation, and ensuring that the analog-to-digital converter 141 can accurately convert the detection signal Vsample in analog signal form.

[0123] See appendix Figure 11 , attached Figure 11 The third schematic diagram of a wearable display device according to one embodiment of this application is shown. In one embodiment, the main control module 140 is connected to the display driver chip 120 and is used to receive the first control signal PWM_LCD and detect the level of the first control signal. When the first control signal PWM_LCD is low, the output duty cycle is adjusted to the second control signal PWM_CPU corresponding to the detection signal Vsample.

[0124] For example, the main control module 140 can detect the level of the first control signal PWM_LCD through devices such as logic gates, comparators, and analog-to-digital converters. When the first control signal PWM_LCD is detected to be low, the second control signal PWM_CPU is triggered to switch, thereby outputting the second control signal PWM_CPU after adjusting the duty cycle to the backlight driver chip 111, thereby reducing brightness jitter and improving the display stability of the display screen.

[0125] See appendix Figure 12 , attached Figure 12 The second schematic diagram shows the structure of the power supply module 130 according to one embodiment of this application. In one embodiment, the power supply module 130 may include a filtering unit 136, which is connected to the charging interface 131 and the detection unit 132 respectively to filter out the AC component in the power supply current.

[0126] The filter unit 136 can be any circuit including filtering components, such as capacitors and resistors. For example, see attached... Figure 11 The diagram illustrates a configuration with n capacitors (C1~Cn) connected in parallel. The first terminal of each capacitor is connected to the equivalent ground terminal GND1, and the second terminal of each capacitor is connected to the charging interface 131 and the detection unit 132. At least one capacitor can be a high-capacity electrolytic capacitor or a tantalum capacitor, and the total capacitance of all capacitors, C1+C2+…+Cn, is ≥ 660uF.

[0127] In this embodiment, the filter unit 136 can filter out the AC component in the power supply current, improving the stability of the power supply current. Furthermore, it prevents excessive impedance of the power supply interface cable from causing a drop in the power supply voltage VBUS, thus affecting the normal power supply to the system.

[0128] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A wearable display device, characterized in that, include: A backlight module includes a backlight driver chip and a light-emitting array. The backlight driver chip includes a switching circuit and a voltage regulation circuit. The two ends of the switching circuit are respectively connected to the voltage regulation circuit and the light-emitting array. The display driver chip is connected to the switching circuit and outputs a first control signal with a first duty cycle to the switching circuit. The first duty cycle is related to the brightness level; The power supply module includes a charging interface and a detection unit; The charging interface is used to connect to an external power source and to transmit the power supply current output by the external power source. The detection unit is connected to the charging interface and is used to output a detection signal corresponding to the power supply current. The main control module is connected to the voltage regulation circuit and the detection unit. The main control module is used to receive the detection signal and output a second control signal with a second duty cycle according to the detection signal; the second duty cycle is negatively correlated with the power supply current. The voltage regulating circuit is used to connect to the power supply voltage and, under the control of the second control signal, adjusts the power supply voltage to a target voltage that is positively correlated with the second duty cycle; the switching circuit, under the control of the first control signal, periodically turns on and off the power supply path between the voltage regulating circuit and the light-emitting array. The light-emitting array emits light under the drive of the target voltage.

2. The wearable display device according to claim 1, characterized in that, The detection unit includes: A sampling resistor, the first end of which is connected to the charging interface, is used to convert the supply current into the corresponding supply voltage; A differential amplifier is provided, wherein the non-inverting input terminal of the differential amplifier is connected to the first terminal of the sampling resistor, the inverting input terminal of the differential amplifier is connected to the second terminal of the sampling resistor, and the output terminal of the differential amplifier is connected to the main control module, for outputting the detection signal corresponding to the supply voltage to the main control module.

3. The wearable display device according to claim 2, characterized in that, The wearable display device also includes: A charging chip is configured with a charging protocol corresponding to the charging interface. The charging chip is connected to the second end of the sampling resistor to receive the supply voltage and convert the supply voltage into a system voltage based on the charging protocol. A power management chip, connected to the charging chip and the main control module, is used to receive the system voltage, convert the system voltage, and then supply power to the main control module.

4. The wearable display device according to claim 3, characterized in that, The power supply module also includes: A step-down unit is connected to the second terminal of the sampling resistor and the charging chip respectively, so as to output a preset voltage to the charging chip; When the charging chip receives the preset voltage, it outputs the system voltage.

5. The wearable display device according to claim 2, characterized in that, The first control signal includes a first signal and a second signal; the second control signal includes a third signal and a fourth signal; the number of backlight modules is two, namely a first backlight module and a second backlight module, the first backlight module is used to provide a display image to a first eye, and the second backlight module is used to provide a display image to a second eye; The voltage regulation circuit of the first backlight module is connected to the second end of the sampling resistor, and is used to drive the light-emitting array to emit light under the power supply voltage according to the first signal and the third signal. The voltage regulation circuit of the second backlight module is connected to the second end of the sampling resistor, and is used to drive the light-emitting array to emit light under the power supply voltage according to the second signal and the fourth signal.

6. The wearable display device according to claim 5, characterized in that, The display driver chip includes: The first driver chip is connected to the switching circuit in the first backlight module and is used to output the first signal to the switching circuit in the first backlight module. The second driver chip is connected to the switching circuit in the second backlight module and is used to output the second signal to the switching circuit in the second backlight module; the timing of the second signal is the opposite of the timing of the first signal.

7. The wearable display device according to claim 2, characterized in that, The main control module includes: An analog-to-digital converter, connected to the output of the differential amplifier, is used to convert the detection signal in analog form into the detection signal in digital form before outputting it. The controller, connected to the analog-to-digital converter and the backlight driver chip, is used to receive the detection signal in digital signal form and output the second control signal with a duty cycle corresponding to the detection signal.

8. The wearable display device according to claim 7, characterized in that, The differential amplifier gain G satisfies: Imin×R1×G≥0.5Vadc and Imax0×R1×G≤Vadc; Wherein, Imin is the preset current adjustment threshold; R1 is the resistance value of the sampling resistor; Vadc is the operating voltage of the analog-to-digital converter; and Imax0 is the preset maximum load current.

9. The wearable display device according to claim 1, characterized in that, The main control module is connected to the display driver chip and is used to receive the first control signal and detect the level of the first control signal. When the first control signal is low, it outputs the second duty cycle adjusted to the second control signal corresponding to the detection signal.

10. The wearable display device according to any one of claims 1 to 9, characterized in that, The power supply module includes: A filtering unit is connected to both the charging interface and the detection unit to filter out the AC component in the power supply current.

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