Patent Application
20250004324
This disclosure relates to the field of circadian-friendly displays, and, more particularly, to a quantum dot (QD) display that has been designed to be circadian friendly.
Identification of non-visual photoreceptors in the human eye (so-called intrinsically photosensitive retinal ganglion cells, or “ipRGCs”) linked to the circadian system has sparked considerable interest in the effects of various light spectra on health and amenity for human beings. High circadian stimulation may lead to positive effects such as resetting sleep patterns, boosting mood, increasing alertness and cognitive performance, and alleviating seasonal affective depression. However, mis-timed circadian stimulation can also be associated with disruption of the internal biological clock and melatonin suppression, and may be linked to illnesses such as cancer, heart disease, obesity, and diabetes.
Circadian stimulation is associated with glucocorticoid elevation and melatonin suppression and is most sensitive to light in the blue wavelength regime. With the preponderance of light-emitting diode (LED) illumination products being based on blue-primary phosphor-converted white-emitting LEDs, the situation has developed that most LED-based illumination sources have higher levels of circadian stimulation than the traditional sources they are intended to replace.
Of particular interest herein is the emission of the blue primary color, which has a peak emission around 460-485 nm.
Applicants have discovered that a spectrum can be configured to appear substantially white, despite a substantial absence of blue radiation, as described in U.S. Pat. No. 9,915,775. For simplicity, such spectra are referred to herein as blue-free. Blue-free emitters are desirable due to their reduced impact on the human circadian cycle, which is important for instance, in the evening before going to sleep.
There is an-ongoing need to provide displays (e.g., computer displays and televisions) with meaningful circadian-friendliness without sacrificing color quality. The present invention fulfills this need among others.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
This invention disclosure is for a quantum dot (QD) LCD display technology that has been designed to be circadian friendly, optimizing visual comfort and health benefits for users by manipulating the emitted light spectrum based on the time of day. This invention integrates the use of a violet LED for a night safe, zero-blue light emission mode, and a cyan LED for a daytime safe, max-blue light emission mode. The system employs quantum dots to produce green and red light, with the potential for different quantum dots to be used for the day and night modes. Additionally, the LEDs used in the system can optionally be partly phosphor-converted.
Accordingly, in one embodiment, the present invention relates to a backlight for a display for emitting at least first and second emitted light, the backlight comprising: (a) a violet LED for emitting violet light; (b) a cyan LED for emitting cyan light; (c) red QDs (RQDs) for emitting red light; (d) green QDs (GQDs) for emitting green light. (e) a driver configured at least for driving the violet LED in a first mode, and driving the cyan LED in a second mode; wherein in the first mode, the violet LED is driven to emit the violet light, a portion of which is absorbed by the RQDs and the GQDs to emit the red light and green light respectively, wherein first emission comprises at least a portion of the violet light said, red light and the green light; and wherein in the second mode, the cyan LED is driven to emit the cyan light, a portion of which is absorbed by the RQDs and the SGQDs to emit the red light and short green light respectively, wherein second emission comprises at least a portion of the cyan light the red light and the green light.
In another embodiment, the present invention relates to a display for emitting at least first and second emitted light, the display comprising: (a) a violet LED for emitting violet light; (b) a cyan LED for emitting cyan light; (c) red QDs (RQDs) for emitting red light; (d) green QDs (GQDs) for emitting green light. (e) a driver configured at least for driving the violet LED in a first mode, and driving the cyan LED in a second mode; wherein in the first mode, the violet LED is driven to emit the violet light, a portion of which is absorbed by the RQDs and the GQDs to emit the red light and green light respectively, wherein first emission comprises at least a portion of the violet light said, red light and the green light; and wherein in the second mode, the cyan LED is driven to emit the cyan light, a portion of which is absorbed by the RQDs and the SGQDs to emit the red light and short green light respectively, wherein second emission comprises at least a portion of the cyan light the red light and the green light.
In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s).
Referring to
Quantum dots (QDs) are tiny semiconductor particles only a few nanometers in size. They are so small that their optical and electronic properties differ from larger particles due to quantum mechanics. They can emit light of specific frequencies if electricity or light is applied to them. The specific frequency or color they emit is a direct consequence of their size; larger quantum dots emit light of longer wavelengths such as red, while smaller quantum dots emit light of shorter wavelengths such as green.
The unique property of quantum dots to tune their emission color just by changing their size makes them an ideal component in display technologies, bio-imaging, solar cells, and many other applications. By carefully choosing the size and composition of the quantum dots, it's possible to engineer a display that produces very specific colors, like the red and green colors discussed in your invention.
Applicant has identified several properties of Quantum dots (QDs) that make them ideal for use in display technologies:
Together, these properties can allow for displays with exceptional color quality, brightness, energy efficiency, and lifespan.
Green-emitting quantum dots are typically smaller in size, usually in the range of 2-4 nanometers. The composition of green quantum dots can vary, but one common type is Cadmium Telluride (CdTe) quantum dots. These have been widely used due to their high quantum yield and stability. However, due to environmental concerns related to cadmium, non-cadmium green-emitting quantum dots, such as Indium Phosphide (InP) quantum dots, have been developed and are seeing increasing use.
Red-emitting quantum dots are larger in size, usually in the range of 4-6 nanometers. Similar to the green quantum dots, Cadmium Selenide (CdSe) quantum dots have been commonly used due to their high efficiency and stability. Again, due to the environmental and safety concerns related to cadmium, non-cadmium alternatives, like Copper Indium Selenide (CuInSe2) quantum dots, have been explored for their potential in emitting red light.
In one embodiment, the display uses a violet LED along with long green and red quantum dots (QDs) for nighttime use. The violet LED emits light at the violet end of the spectrum, which is less disruptive to the circadian rhythm than light at the blue end of the spectrum. Violet light is less likely to suppress melatonin production and therefore less likely to disrupt sleep patterns if the display is used at night.
Long Green Quantum Dots (LGQDs) are designed to convert the violet light from the LED into green light. Green light, particularly long-wavelength green light, is less impactful on the circadian rhythm than blue light.
Red Quantum Dots (RQDs) convert the violet light from the LED into red light. Red light has the least impact on the circadian rhythm of all the colors in the visible spectrum.
By using a violet LED along with long green and red QDs, the display minimizes the amount of blue light emitted during nighttime use. This can help to prevent the suppression of melatonin production and thereby reduce potential disruption to the user's sleep patterns and other potential negative health effects associated with nighttime exposure to blue light. It is a more circadian-friendly option for using displays in the evening or at night.
During the day, exposure to blue light is beneficial as it promotes alertness, improves mood, and helps maintain our sleep-wake cycle. In one embodiment, the display uses a cyan LED along with short green and red quantum dots (QDs) for daytime use. The cyan LED emits light in the cyan-blue spectrum. During the day, exposure to this kind of light can help maintain a healthy circadian rhythm by signaling to the body that it is daytime, which helps promote alertness and cognitive function.
Short Green Quantum Dots (SGQDs) convert the cyan light from the LED into shorter wavelength green light. This light has some effect on the circadian rhythm, but it's not as potent as blue light. The green light can help create a bright and vibrant display without significantly adding to the blue light exposure.
Red Quantum Dots (RQDs) convert some of the cyan light from the LED into red light. Red light has little to no impact on the circadian rhythm, but it's essential for achieving a full range of color on the display.
By using a cyan LED along with short green and red QDs during daytime use, this display provides the benefits of blue light, helping to maintain alertness and cognitive function, while still offering a full, vibrant range of colors. This setup allows for an optimal balance between circadian rhythm regulation and display performance during daytime hours.
A display system that uses a single quantum dot (QD) sheet with red and green QDs and two different LED backlights (cyan and violet) can be designed to switch between the LEDs based on the time of day. This design aims to optimize display performance while also considering the user's circadian rhythm.
Referring to
Referring to
The different SPD emission spectrums of the first and second light emissions have a significant effect on circadian stimulation. In one embodiment, the first emission has a first circadian stimulus (CS) less than half a second CS of the second emission. In a more particular embodiment, the first emission has a first CS less than ⅓ or even ¼ of a second CS of the second emission.
The specifics of the lighted emitters—i.e. the LEDs and quantum dots can be optimized by those of skill the art in light of the disclosure. That said, in one embodiment, the violet LED has a peak wavelength between 395 and 440 nm, the cyan LED has a peak wavelength between 470 and 520 nm, the RQDs have a peak wavelength between 600 and 65 nm, the LGQDs have a peak wavelength between 530 and 580 nm, and SGQDs have a peak wavelength between 500 and 540 nm.
In one embodiment, the LED and QDs are used as a backlight 100 for a display 150 is shown in
In one embodiment, the quantum dots are disposed in QD sheet 107. For example, in one embodiment, the QD sheet 107 may contain red and long/short green quantum dots 104, 105, 106 dispersed within a transparent matrix 108 as shown in
In one embodiment, the display also comprises a liquid crystal display (LCD) panel 110. Specifically, the light from LED sources passes through the QD sheet such that a portion of the LEDlight is converted by the red and green QDs, and this combination of LED and converted light passes through the LCD panel 110. This panel modulates the intensity and color of the light to create the final image that is visible to the user. Those of skill in the art in light of this disclosure can readily design the LCD panel to work optimally with the QD sheet and the dual backlight system to maximize display performance under both lighting conditions.
In one embodiment, the display is protected by a screen 120 which is well known in the art.
In one embodiment, the driver 130 for powering the LEDs comprises a controller 131 that determines which LED backlight should be active based on the time of day. The controller can be configured in various embodiments. For example, it may be based on a real-time clock, ambient light sensor, or user-defined settings to decide when to switch between the cyan and violet LEDs.
Upon receiving the signal from the controller, the display system changes its backlight source. If the controller determines that the user is in their daytime phase, the cyan LED backlight is activated. If the controller determines the user is in their nighttime phase, the violet LED backlight is activated. This way, the display adapts to the user's circadian rhythm, promoting better sleep health and overall well-being.
The user can provide feedback or manually override the automatic settings if necessary. This feedback can be incorporated into the data analysis to improve the accuracy of the body clock time prediction and the appropriateness of the display settings.
When switching between the first and second modes, the driver may either gradually or instantly switch between the cyan and violet backlights, depending on the desired implementation.
In one embodiment, the driver is configured to operate in a third mode in which both said violet and said cyan LEDs are powered. In another embodiment, the driver is configured to operate in just the first, second, or third mode.
By implementing this design, the display can provide a rich, vibrant range of colors while also considering the user's circadian rhythm. The cyan LED backlight for daytime use supports alertness and cognitive function, while the violet LED backlight for nighttime use minimizes melatonin suppression, reducing potential sleep disruption and other negative health effects associated with nighttime blue light exposure.
Furthermore, integrating the system with an external controller 200 that tracks the body clock time (also known as the circadian rhythm) of a user can provide a personalized and more effective way to manage the display settings. For example, in one embodiment, the external controller is a wearable device like a smartwatch or fitness tracker, or even a smartphone application, which tracks the user's circadian rhythm. This could be achieved by collecting and analyzing data like sleep patterns, activity levels, heart rate variability, light exposure, and other relevant health metrics.
In one embodiment, either the controller or the external controller (or both) uses machine learning algorithms or other data analysis techniques to determine the user's current body clock time. For example, it might infer that the user is in their “daytime” phase if they have been active and exposed to bright light, while it might infer that they are in their “nighttime” phase if they have been inactive and in dim light.
In one embodiment, the controller communicates with the display system via a wireless signal 201 like Bluetooth, WiFi or NFC.
Such a system provides a personalized display experience that respects and aligns with the user's circadian rhythm. Not only does this improve the visual comfort of the display, but also it contributes to better sleep health and overall well-being for the user.
Having thus described a few particular embodiments of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements as are made obvious by this disclosure are intended to be part of this description though not expressly stated herein and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only, and not limiting. The invention is limited only as defined in the following claims and equivalents thereto.
This application claims the benefit of U.S. Provisional Application No. 63/468,371 filed May 23, 2023, the contents of which are incorporated by reference herein in their entirety as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 63468371 | May 2023 | US |
