Display device, method of operating display device, and method of manufacturing display device

Abstract

A display device (1) includes: a substrate (10) including a main surface (12); and a plurality of emitters (20) arranged in the pixels (2) on the main surface (12) of the substrate (10), where each emitter (20) comprises a light emitting diode (LED) configured to emit light during operation. The display device (1) further comprises a sensor (30) in at least one pixel (2), the sensor (30) being configured to sense light during operation. The display device (1) further comprises at least one evaluation circuit (40) configured to evaluate the proximity of the object (100) above the display device (1) based on the light sensed by the sensor (30). Further, a method of operating a display device (1) and a method of manufacturing a display device (1) are provided. The transmitter and the sensor may be implemented as micro LEDs.

Description

[0001] The display device, the method of operating the display device, and the method of manufacturing the display device are described in detail.

[0002] Displays, especially micro-LED displays, have many metal layers to fan out driver signals to the emitter. Therefore, they are not very transparent, making it impossible to use back-sensing technologies as in, for example, OLED displays. Proximity sensors can be placed outside the display, for example, in a notch in the display.

[0003] At least one objective of a particular implementation is to provide in-screen sensing.

[0004] This objective is achieved by the subject matter and method according to the independent claim. Advantageous implementations and developments of the subject matter and method are characterized in the dependent claims and are also disclosed in the following description and drawings.

[0005] According to at least one embodiment, a display device is provided.

[0006] Display devices include displays. For example, a display device is or is integrated into a touchscreen, smartwatch, smartphone, tablet, dashboard, or car dashboard.

[0007] According to at least one embodiment, the display device includes a substrate, the substrate including a main surface.

[0008] The substrate can also be referred to as a carrier or backplane. For example, the substrate may be a silicon backplane or a flexible planar surface. For example, the substrate may be or may include a foil. Therefore, the substrate may be rigid or flexible. The substrate has a main extending plane. Here and below, the lateral direction refers to the direction extending parallel to the main extending plane. The vertical direction refers to the direction extending perpendicular to the main extending plane. The main surface of the substrate is parallel to the main extending plane of the substrate.

[0009] According to at least one embodiment, the display device includes a plurality of emitters arranged in pixels on the main surface of a substrate.

[0010] This can mean that emitters are arranged in groups. Pixels can form rectangular or square areas on the main surface of the substrate, wherein said areas are adjacent to each other. Pixels form the display screen of a display device. Each pixel may include one or more emitters. In addition, each pixel may include wiring for electrically connecting the emitters. Pixels and / or emitters in pixels can operate individually or in groups. The arrangement of emitters on the main surface of the substrate can mean that they are mounted on the main surface. This can mean that they are not integrated or embedded in the substrate. For example, they are attached to the substrate by means of a transfer process, particularly a batch transfer process, in which multiple emitters are attached to the substrate simultaneously.

[0011] According to at least one embodiment, each emitter includes a light-emitting diode (LED) configured to emit light during operation.

[0012] Here and below, light can generally refer to electromagnetic radiation. Each emitter is configured, for example, to emit electromagnetic radiation in a main emission direction during intended operation. The main emission direction is preferably oriented perpendicular to the main surface of the substrate. In particular, each emitter is configured to emit electromagnetic radiation having a dominant wavelength in the spectral region visible to the human eye, i.e., between 380 nm and 750 nm. Different emitters can emit light in different wavelength ranges. Each pixel may include one or more emitters, and therefore one or more LEDs. Each pixel may include at least three (e.g., red, green, blue) LEDs to cover the visible wavelength range. Each pixel may also include more than three LEDs to provide a degree of redundancy and / or additional functionality.

[0013] According to at least one embodiment, the display device includes a sensor in at least one pixel, the sensor being configured to sense light during operation.

[0014] In other words, the display device includes at least one sensor. In other words, at least one of the plurality of pixels in the display device includes a sensor. This can mean that the pixel includes only a sensor or includes a sensor in addition to one or more emitters. Specifically, the pixel includes a sensor and at least three emitters to cover the visible wavelength range. The sensor being configured to sense light during operation can mean that the sensor is configured to sense ambient light and / or to sense display light, for example, after reflection at an object. Display light refers to light emitted by the emitters of the display device. The sensor can be sensitive to a specific wavelength range in the visible spectrum. The sensor can have a viewing angle. In particular, the viewing angle includes a vertical direction, making the sensor a “top-view” sensor. The illumination field of the emitter and the field of view of the sensor can at least overlap. The display device can include more than one sensor distributed in corresponding pixels of the display device. More than one sensor can also be arranged in a single pixel. In the case of two or more sensors in the display device, the sensors can be sensitive to light in different wavelength ranges.

[0015] According to at least one embodiment, the display device includes at least one evaluation circuit. The evaluation circuit is configured to evaluate the proximity of an object above the display device based on light sensed by a sensor.

[0016] For example, the evaluation circuitry is integrated into the substrate. However, the evaluation circuitry can also be arranged adjacent to the pixel on the main surface of the substrate or within the pixel. The evaluation circuitry can also be arranged on the opposite rear surface of the substrate and electrically connected to the pixel via a through-hole (TSV) through the substrate. Alternatively, the evaluation circuitry can be arranged in or on another substrate. An object being located above the display device can mean that the object is vertically positioned above the display screen, particularly in the direction in which light is emitted by the emitter and at least one sensor is observing. Therefore, ambient light sensed by the sensor may be blocked by the object. Additionally, display light (i.e., light emitted by the emitter) can be reflected by the object. The proximity of the object above the display screen can be determined by evaluating the blocked ambient light and / or the reflected light. The evaluation circuitry is electrically connected to the sensor or multiple sensors to evaluate the light intensity sensed by the sensor. Furthermore, the evaluation circuitry can include circuitry for driving the emitter and biasing the emitter. Therefore, the evaluation circuitry can include a driving circuitry system for the emitter and can be electrically connected to at least some of the emitters in the pixel. The display device can include more than one evaluation circuitry. For example, each evaluation circuitry is assigned to a group of pixels, for example, 16. A 16-pixel group. The corresponding evaluation circuitry can drive the transmitter and evaluate signals from sensors within the pixel group.

[0017] According to at least one embodiment, the display device includes: a substrate including a main surface; and a plurality of emitters disposed in pixels on the main surface of the substrate, wherein each emitter includes a light-emitting diode (LED) configured to emit light during operation. The display device also includes a sensor in at least one pixel configured to sense light during operation. The display device further includes at least one evaluation circuit configured to evaluate the proximity of an object above the display device based on the light sensed by the sensor.

[0018] The display device described herein is based in particular on the following considerations.

[0019] Displays, especially micro-LED displays, have many metal layers to fan out driver signals to the emitter. Therefore, they are not very transparent and cannot use back-screen sensing technology as in, for example, OLED displays. Thus, it is advantageous to use in-display sensing technology, where sensors are embedded and integrated into the display, eliminating the need for a display notch. In other words, integrating the proximity sensor into the display removes any notch from the display, eliminating the need for back-screen sensing.

[0020] Sensors can be embedded in the display screen. The sensors are used to detect objects near the display screen by detecting backscattered display light and / or ambient light. If several pixels include corresponding sensors, the display screen can be partially or completely filled with additional sensors.

[0021] The sensing can be synchronized with the LED's pulse width modulation (PWM), allowing for the differentiation between backscattered display light and ambient light. The differential signal from the two sensing channels generates the object's outline.

[0022] Therefore, in-screen depth and / or proximity sensing is provided. Possible applications of in-screen depth and / or proximity sensing include smart surfaces, hover detection, predictive touch, and distance measurement.

[0023] According to at least one embodiment, each transmitter is formed of a micro LED.

[0024] In a broad definition, a microLED can be considered any light-emitting diode (LED) with a particularly small size, typically not a laser. As is customary, and this is very important besides size, the growth substrate is removed from the microLED so that the typical height of such a microLED is in the range of, for example, 0.5 µm to 10 µm. In principle, a microLED does not necessarily have to have a rectangular radiating surface. Typically, for example, an LED can have a radiating surface where, in a planar view of the stacked layers, any lateral extent of the radiating surface is less than or equal to 100 µm or less than or equal to 70 µm. For example, in the case of rectangular microLEDs, edge lengths of less than or equal to 70 µm or less than or equal to 50 µm are often cited as standards, especially in a planar view of the stacked layers. In most cases, utilizing... A non-destructive, removable retention structure holds such microLEDs on a chip. Currently, microLEDs are primarily used in displays. MicroLEDs form pixels or subpixels and emit light of a defined color. The small pixel size and high density at close range make microLEDs particularly suitable for small, monolithic displays for AR applications, especially data glasses. Additionally, other applications are being developed, particularly for use in data communication or pixelated lighting applications. Different ways of spelling microLEDs can be found in relevant literature, such as... , , , Or a miniature light-emitting diode.

[0025] According to at least one embodiment, the pixel is formed as an RGB pixel, wherein a first emitter configured to emit red light, a second emitter configured to emit green light, and a third emitter configured to emit blue light are arranged.

[0026] Specifically, each emitter is designed to emit radiation at a different dominant wavelength. The dominant wavelength is understood to be the wavelength in the emission spectrum where the intensity reaches its global maximum. For example, in its intended operation, the first emitter is designed to emit red radiation, the second emitter is designed to emit green radiation, and the third emitter is designed to emit blue radiation. This red, green, and blue (RGB) arrangement is particularly suitable for the pixels of a display device. For example, red light can refer to light in the wavelength range of 640 nm to 780 nm. For example, green light can refer to light in the wavelength range of 490 nm to 570 nm. Blue light can refer to light in the wavelength range of 430 nm to 490 nm. Thus, the entire visible spectrum is covered by an additive color mixture of the three components R, G, and B. As mentioned above, the emitters can be formed from corresponding LEDs, particularly micro LEDs. Depending on the color of the light, LEDs can include different semiconductor materials, such as gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), gallium phosphide (GaP), aluminum indium gallium phosphide (AlInGaP), indium gallium nitride (InGaN), and / or gallium nitride (GaN). In possible implementations, each pixel is formed as an RGB pixel including a red light emitter, a green light emitter, and a blue light emitter. Pixels can also include more than one emitter for each color, for example, to provide a degree of redundancy.

[0027] According to at least one embodiment, the sensor is formed as a photodiode, wherein the photodiode is embedded in a substrate.

[0028] This can mean that the photodiode (PD) is integrated into and / or formed within the substrate. Therefore, the photodiode is an embedded photodiode. Specifically, if the substrate comprises silicon, the photodiode can be a silicon photodiode, but other materials are also possible. For efficiency reasons, silicon photodiodes can have a larger dimension in the lateral direction and can be thicker than the emitter. Silicon photodiodes are suitable for detecting visible light. Therefore, a substrate on which the emitter is disposed has additional sensing capabilities. The emitter can be disposed in an area outside the photodiode on the substrate.

[0029] Alternatively, photodiodes are arranged adjacent to the emitter on the main surface of the substrate.

[0030] Such photodiodes can be formed into individual detector chips. In particular, the photodiode can be a miniature PD. This can mean that the photodiode has a similar size to each emitter in the emitter, especially if they are formed as miniature LEDs. For efficiency reasons, the photodiode can also have a larger size. If the photodiode is arranged on a substrate, its thickness can preferably be similar to or equal to the thickness of the emitter. Arranging the photodiode on a substrate can mean that it is mounted on the substrate, for example, by means of a (batch) transfer process. Arranging the photodiode adjacent to the emitter can mean that the photodiode and the emitter are arranged in a common pixel.

[0031] According to at least one embodiment, the sensor is implemented as an LED, particularly a micro LED, which is arranged adjacent to the emitter on the main surface of the substrate and configured to be biased for sensing photocurrent.

[0032] Implementing a sensor as a (miniature) LED can mean that the sensor and emitter have the same or similar structure. Specifically, the sensor and emitter can be formed by stacking a common semiconductor layer. A sensor designed as an LED can emit light when properly biased, particularly when the sensor is forward biased. However, if the sensor is zero-biased or reverse-biased, it is configured to sense photocurrent based on the light illuminating the sensor. It has been found that miniature LEDs emitting red, green, and blue light achieve external quantum efficiency (EQE) values ​​exceeding 20% ​​under reverse or zero bias, depending on the wavelength to be detected. Thus, miniature LEDs emitting red, green / blue light, used as sensors, span the entire visible spectrum. In other words, the EQE curves of blue or green and red miniature LEDs match together to span the visible wavelength range. Therefore, additional red or blue / green miniature LEDs can be placed in some or all pixels for sensing. Moreover, as mentioned above, pixels can include additional (miniature) LEDs for redundancy. These additional emitters can be used as sensors, thereby reducing the complexity of the manufacturing process. (Miniature) LEDs can be operated and biased depending on whether they are used as emitters or sensors. Dynamic use as both emitters and sensors is also possible. This means that an emitter can be used as a sensor by dynamically changing its electrical bias, for example, by integrating a multiplexer into the driver circuit. Biasing LEDs for sensing photocurrent represents a simple and cost-effective solution for providing sensing capabilities to display devices.

[0033] According to at least one embodiment, the transmitter and sensor are manufactured using a common manufacturing process.

[0034] This could mean that at least some of the process steps used to manufacture the emitter are also used to manufacture the sensor. Specifically, this is true if both the emitter and sensor are formed as (miniature) LEDs. Therefore, the emitter and sensor can be manufactured on a common carrier substrate. They can be simultaneously transferred to the substrate of the display device. This facilitates the manufacturing of the display device and reduces costs. All display LEDs can also be transferred at double density for redundancy, thus avoiding the need to repair damaged LEDs. LEDs that are not used for emitting light but are functional can be used for sensing. This would mean that the sensor has less than 100% coverage but can still have satisfactory functionality.

[0035] According to at least one embodiment, the display device includes a plurality of sensors configured to sense light during operation, wherein the sensors are distributed throughout the display screen in corresponding pixels of the display device.

[0036] All features disclosed for a sensor are also disclosed for multiple sensors. The sensor mentioned above can be one of multiple sensors. In a possible implementation, each pixel includes at least one sensor. However, it is also possible that only a subset of pixels includes at least one sensor. For example, each second pixel or each third pixel includes a sensor. Preferably, the sensors are uniformly distributed. Multiple sensors arranged in corresponding pixels form a distributed proximity sensor, which has more redundancy than local sensors (e.g., at a notch in the display or in a dedicated area behind the display). In addition, it is less sensitive to interference such as the sensor being covered by hair, dirt, or dust. Integrating the proximity sensor into the display eliminates any notches in the display and eliminates the need for sensing behind the display, such as behind an OLED. When the sensors are distributed throughout the display, the distributed proximity sensor has 2D spatial resolution.

[0037] According to at least one embodiment, the viewing angle of at least one sensor is different from the viewing angle of at least another sensor in the display device.

[0038] This can mean that the fields of view of corresponding sensors among multiple sensors can be different. However, the fields of view can overlap. For example, some sensors among multiple sensors are configured to sense light from a first direction, while some other sensors among multiple sensors are configured to sense light from a second direction, where the first and second directions are different. However, the first and second directions can share a common directional component. Different viewpoints can be implemented for additional spatial information.

[0039] According to at least one embodiment, the display device further includes an aperture and / or light barrier and / or microlens assigned to a respective sensor, the aperture, light barrier and microlens being configured to define the viewing angle of the respective sensor.

[0040] Multiple light barriers and / or apertures and / or microlenses can be provided. Each aperture / light barrier / microlens can be assigned to a corresponding sensor among multiple sensors. For example, the aperture and / or light barrier includes an opaque material, such as a metal layer or an opaque plastic material. The aperture and / or light barrier can prevent light from unwanted directions from reaching the sensor. For example, the aperture is arranged vertically above the sensor, allowing only light from the vertical direction to reach the sensor. The light barrier can be arranged offset above the sensor or at the side of the sensor, blocking light from that side. The microlens can be centrally positioned above the sensor or shifted laterally. Thus, light from different directions can be focused onto the sensor surface. The microlens can be part of a microlens array. For example, a microlens array is formed by wafer-level optics (WLO). With the aid of apertures, light barriers, and microlenses, the sensor can have different viewing angles. Different viewing angles can be achieved for additional spatial information. Shielding elements such as apertures and light barriers allow for 2D spatial resolution of the sensor. Furthermore, depth information can be resolved using micro-optical elements such as microlenses. Using such a 3D in-screen, full-area proximity sensor, hover detection is also possible, enabling predictive touch. Predictive touch means sensing an approaching object before it is touched, a feature advantageous for touch surfaces.

[0041] According to at least one embodiment, the display device further includes a transparent cover that covers the pixels.

[0042] The cover is transparent to visible light. For example, the cover may be made of glass or transparent plastic material. The cover may be positioned directly above the transmitter and (multiple) sensors. There may also be a distance between the cover and the transmitter and (multiple) sensors. The cover protects the transmitter and (multiple) sensors. Additionally, the cover may provide other functions; for example, it may be formed as a touchscreen.

[0043] According to at least one embodiment, a light barrier and / or an aperture and / or a microlens are constructed on the cover.

[0044] This could mean that the light barrier and / or aperture and / or microlens are attached or mounted to the cover. These components can also be integrally formed with the cover. In particular, the microlens can be monolithically integrated into the cover. Therefore, the light barrier and / or aperture and / or microlens can be aligned with corresponding sensors on or within the substrate.

[0045] According to at least one embodiment, the light barrier is formed as a wall, which is attached to the substrate adjacent to the corresponding sensor.

[0046] As mentioned above, a light barrier can be positioned on the side of the sensor to block light from that side. The barrier can be mounted to or integrally formed with the substrate. Attaching the barrier to the substrate facilitates alignment with the corresponding sensor.

[0047] According to at least one embodiment, the evaluation circuit is configured to generate a first detection signal using ambient light sensed by a sensor that is obscured by an object.

[0048] Alternatively or otherwise, the evaluation circuit is configured to generate a second detection signal using light emitted by the transmitter and reflected by the object and sensed by the sensor.

[0049] The first and second detection signals can be signals corresponding to the intensity of the sensed light. As mentioned above, the sensor can be configured to sense ambient light. If an object appears or moves above the display screen, the ambient light is blocked by the object, and the light intensity decreases. Therefore, a shadow image can be generated. Additionally, the sensor can be configured to sense light emitted by an emitter and reflected by an object located above the display screen. The closer the object, the higher the intensity of the backscattered display light. Therefore, an image of the backscattered display light can be generated. The evaluation circuit uses measurements from one or more sensors to determine that the object is located above the display screen. Furthermore, by evaluating changes in the size and shape of the generated image and the intensity of the sensed light, the distance from the object to the display screen can be determined. It is also possible to detect movement of an object, such as a user's finger. Therefore, the first and second detection signals can be used for proximity, depth, and gesture recognition.

[0050] According to at least one embodiment, the evaluation circuit is configured to calculate a differential signal based on a first detection signal and a second detection signal.

[0051] Differential signals from shadow images of backscattered display light and ambient light result in high contrast at the edges of objects (differential lock detection). For example, display light backscattered from a fingertip and ambient light occluded from the fingertip are used for finger tracking detection.

[0052] Therefore, hover detection is possible. Hover detection refers to detecting an object (without touching the display screen) at a distance of 1 mm to approximately 20 mm from the display screen. Hover movement tracking can be used for "mouse hover" effects and other display user interactions where aiming without action is necessary (predictive touch). Prior art hover detection is possible using a pencil connected to the display screen via electrical feedback. This disclosure achieves hover detection of one or more fingertips because the display device implements short-range 3D sensing with high resolution to track fingers above the display screen. To detect the distance of the object to the display screen, the sensor can be equipped with miniature optics (as mentioned above) to realize left and right view images and calculate the distance based on image shift. The relative distance change in continuous tracking can also be obtained from the shape and size changes and intensity changes in the backscattered display light.

[0053] In addition, a method for operating a display device is provided. This method of operation can preferably be performed using the display device described above. This means that all features disclosed for the display device are also disclosed for the method of operating the display device, and vice versa.

[0054] According to at least one embodiment, a method of operating a display device is performed using the display device, which includes a plurality of emitters arranged in pixels on the main surface of a substrate, a sensor in at least one pixel, and at least one evaluation circuit.

[0055] According to at least one embodiment, the method includes emitting light by an emitter, wherein each emitter includes a light-emitting diode (LED). Specifically, the emitter emits light in a main direction extending perpendicular to the main surface of the substrate. Each emitter / LED has an illumination field.

[0056] According to at least one embodiment, the method includes sensing light by a sensor. The sensed light may be ambient light and / or light reflected from an object above the display device by an emitter. Preferably, the emitter and sensor are arranged such that display light does not reach the sensor directly, but only via reflection from the object. For example, a light barrier is arranged between the emitter and the sensor, and / or the sensor is outside the illumination field of the emitter.

[0057] According to at least one embodiment, the method includes evaluating the proximity of an object above a display device by an evaluation circuit based on sensed light. The proximity of the object can be determined by ambient light sensed by a sensor that is obscured by the object. Alternatively, the proximity of the object can be determined by backscattered display light (i.e., light emitted by an emitter and reflected by the object).

[0058] According to at least one embodiment, the display device includes a plurality of emitters arranged in pixels on the main surface of a substrate, a sensor in at least one pixel, and at least one evaluation circuit. The method of operating the display device includes: emitting light by the emitters, wherein each emitter includes a light-emitting diode (LED). It also includes sensing the light by the sensor. Furthermore, it includes evaluating the proximity of an object above the display device by the evaluation circuit based on the sensed light.

[0059] Therefore, in-screen proximity sensing is possible. A sensor is embedded in the display. The sensor is used to detect objects near the display by detecting backscattered display light and / or ambient light. Thus, in-screen depth and / or proximity sensing is possible. If several pixels include corresponding sensors, the display can be partially or completely filled with additional sensors, thereby providing a specific spatial resolution. Possible applications of in-screen depth and / or proximity sensing include smart surfaces, fingerprint recognition, hover detection, and distance measurement.

[0060] According to at least one embodiment, the method further includes adjusting the brightness of the emitted light by pulse width modulation.

[0061] Pulse Width Modulation (PWM) for LEDs is a technique used to control the brightness of an LED by changing the duty cycle of a pulsating electrical signal. In PWM, the LED is rapidly turned on and off at a fixed frequency, and the average intensity of light perceived by the human eye depends on the ratio of the time the LED is on (conduction state) to the time it is off (off state) during each cycle. PWM is a highly efficient and effective method for controlling LED brightness without changing the LED's forward current.

[0062] According to at least one embodiment, sensing light includes: sensing ambient light when the transmitter is in an off state during pulse width modulation, and / or sensing reflected light when the transmitter is in an on state during pulse width modulation.

[0063] Therefore, the sensing can be synchronized with the pulse width modulation of the LED, allowing for the differentiation between backscattered display light and ambient light. Additionally, the differential signal from the two detection channels generates the object's outline.

[0064] According to at least one embodiment, light sensing is performed continuously during pulse width modulation, and the sensed light is evaluated by filtering the detection signal in the frequency space.

[0065] This means that both display light and ambient light are sensed throughout the complete PWM cycle, that is, during the LED's on and off states. Therefore, the detection signal contains information about both ambient light and backscattered display light. Knowing the PWM frequency, post-processing can distinguish between the two channels.

[0066] According to at least one embodiment, the method further includes evaluating the distance between the object and the display device, wherein the distance is determined by: evaluating the intensity of reflected light, and / or evaluating image displacement captured by at least two sets of sensors with different viewing angles, and / or evaluating shape and size changes of images captured by multiple sensors.

[0067] The distance from an object to the main surface of a substrate, the emitting surface of an emitter, the sensing surface of a sensor, or the cover of a display device can be measured. The distance from the object to the display device can be determined by evaluating the intensity of the reflected light. The closer the object is to the display screen, the higher the intensity of the backscattered display light. In particular, the relative distance change during continuous tracking can be obtained from the intensity change in the backscattered display light. Alternatively or additionally, the distance from the object to the display screen can be determined by evaluating the image shift captured by at least two sets of sensors with different viewing angles. As mentioned above, the viewing angle of the sensors can be modified by aperture, light barriers, and / or microlenses. Thus, for example, a left-view sensor and a right-view sensor can be implemented. Right-view pixels and left-view pixels can be uniformly distributed throughout the entire display screen, thereby generating a right-view image sensor and a left-view image sensor. The right-view image sensor and the left-view image sensor will see a shifted shadow image (ambient light blocked by the object) of the approaching object. The image shift depends on the distance to the object. By analyzing the two images, distance information can be extracted. This process can be analogous to phase-detection autofocus in a camera device. Alternatively, the relative distance change in continuous tracking can also be obtained from the shape and size changes of images captured by multiple sensors.

[0068] In addition, a method for manufacturing a display device is provided. All features disclosed for the display device are also disclosed for the method of manufacturing the display device, and vice versa.

[0069] Methods of manufacturing a display device include providing a substrate. For example, the substrate is a backplate or a flexible plane, or is formed from a backplate or a flexible plane.

[0070] A method of manufacturing a display device further includes mounting a plurality of emitters on the main surface of a substrate, wherein the emitters are arranged in pixels, and each emitter includes a light-emitting diode (LED) configured to emit light during operation. Specifically, the emitters are formed from micro-LEDs, and mounting the emitters on the substrate includes the bulk transfer of the emitters from a carrier substrate to the substrate of the display device. For example, elastomeric molding is used for bulk transfer.

[0071] The method of manufacturing a display device further includes forming a sensor in at least one pixel, the sensor being configured to sense light during operation.

[0072] Forming a sensor can include embedding a photodiode in a substrate. This can mean, for example, that the substrate is a semiconductor substrate, and the photodiode is formed in the substrate using a semiconductor fabrication process, such as a CMOS process. Thus, the photodiode is integrated into the substrate. Alternatively, forming a sensor can include mounting a photodiode adjacent to an emitter on the main surface of the substrate. This can mean that the photodiode forms a single detector chip that is transferred to and attached to the substrate. For example, the photodiode is a miniature photodiode and is transferred to the substrate in a similar manner to the emitter, particularly by means of a separate batch transfer. As another alternative, forming a sensor can include mounting an LED adjacent to an emitter on the main surface of the substrate and biasing the LED for sensing photocurrent. The “sensor LED” can have a similar or identical structure to the “emitter LED.” Thus, the sensor and emitter can be formed using a common fabrication process, and they can be transferred to the substrate simultaneously. The sensor and emitter can differ only in how they are biased. For example, the sensor is a reverse-biased or zero-biased (miniature) LED.

[0073] A method of manufacturing a display device further includes providing at least one evaluation circuit configured to evaluate the proximity of an object above the display device based on light sensed by a sensor. The evaluation circuit can be formed in a substrate. The evaluation circuit can be an integrated circuit (IC) and can provide additional functionality. The evaluation circuit can also be attached to the substrate. In this case, the evaluation circuit can be implemented as a miniature IC, i.e., an integrated circuit that can be separated and transferred as a silicon wafer with high-density integrated circuits. Alternatively, the evaluation circuit is attached to another substrate and connected to a pixel via an electrical connection, such as a flexible connection.

[0074] The following description of the accompanying drawings further illustrates and explains aspects of the display device, operating method, and manufacturing method. Components and parts that function identically or have the same effect in the display device are indicated by the same reference numerals. Identical or substantially identical components and parts may be described only with respect to the accompanying drawing in which they first appear. Their description is not necessarily repeated in subsequent drawings.

[0075] Figure 1 a to Figure 1 c illustrates various examples of integrating sensors into display devices.

[0076] Figures 2 to 9 A display device according to an embodiment of the present invention is shown.

[0077] Figures 10 to 14 A method for operating the display device according to an embodiment of the present invention is shown.

[0078] Figure 15 The external quantum efficiency of a microLED is shown if it is biased for sensing photocurrent.

[0079] exist Figure 1 a to Figure 1 Figure c shows different examples of integrating sensor 30 into display device 1. Sensor 30 may be a proximity sensor, etc. Figure 1 A top view shows the display device 1. The display device 1 includes a display area. The sensor 30 is arranged outside the display area in a notch of the display screen. The disadvantage of such a display device 1 is that the display area is reduced, and the sensor 30 is not a distributed sensor, but a single sensor that is easily disturbed. For example, the sensor 30 may be covered by hair, dust or other dirt.

[0080] Figure 1 b illustrates another example of a display device 1 including sensor 30. In this example, sensor 30 is arranged behind the display area, which is possible if the display device 1 is or includes a transparent display such as an OLED display. However, in this case, sensor 30 is also limited to a relatively small sensor area behind the display.

[0081] Figure 1 c illustrates an embodiment of the present invention. The display device 1 includes a substrate 10 having a main surface 12 (in... Figure 5 a and Figure 5 (shown in b). A plurality of emitters 20 are arranged in pixels 2 on the main surface 12 of the substrate 10, wherein each emitter 20 includes a light-emitting diode (LED) configured to emit light during operation (see subsequent figures). Additionally, a sensor 30 is integrated in at least one pixel 2, and the sensor 30 is configured to sense light during operation (see subsequent figures). The display device also includes at least one evaluation circuit 40 (in... Figure 5 a and Figure 5 (as shown in b), the evaluation circuit is configured to evaluate the object 100 above the display device 1 based on the light sensed by the sensor 30 (see example). Figure 12 and Figure 13 The degree of proximity.

[0082] For example, each pixel 2 or at least a subset of pixels 2 includes a corresponding sensor 30. Therefore, the sensor area can be large-scale and can form a distributed proximity sensor 30. Distributed proximity sensors have more redundancy than local sensors and are less sensitive to interference. Integrating the proximity sensor 30 into the display eliminates any notches in the display and eliminates the need to place the sensor behind the display, such as sensing behind an OLED, for example. The display does not need to be transparent.

[0083] Figure 2 a and Figure 2 b illustrates different implementations of corresponding pixels 2 within display device 1. According to... Figure 2 a and Figure 2 b. Pixel 2 is formed as an RGB pixel 2, wherein a first emitter 20-1 configured to emit red light, a second emitter 20-2 configured to emit green light, and a third emitter 30-3 configured to emit blue light are arranged therein. The emitters 20 are formed as LEDs, particularly micro LEDs. The emitters 20 are arranged along the diagonal of pixel 2. However, different arrangements are also possible. Figure 2 a and Figure 2 Pixel 2 in b includes a corresponding sensor 30 arranged diagonally along the emitter 20. According to Figure 2 The sensor 30-1 of pixel 2 is formed of an LED, particularly a micro-LED, capable of emitting blue or green light in forward bias mode. However, the LED is configured to be biased for sensing photocurrent. That is, the LED is configured to be reverse biased or zero biased. It has been found that blue or green micro-LEDs can generate photocurrent in reverse bias with an external quantum efficiency of approximately 20% or higher in the wavelength range between 350 nm and 500 nm. Figure 2 The sensor 30-2 of pixel 2 is formed by an LED, particularly a micro-LED, capable of emitting red light in forward bias mode. However, the LED is configured to be biased for sensing photocurrent. That is, the LED is configured to be reverse biased or zero biased. It has been found that red micro-LEDs can generate photocurrent in reverse bias with an external quantum efficiency of approximately 20% or higher in the wavelength range between 500 nm and 650 nm. Therefore, the visible wavelength range is covered by means of reverse biased or zero biased (micro)LEDs of red and blue / green light. The display device 1 may include different subsets of pixels 2, wherein a first subset of pixels 2 includes blue / green LEDs serving as sensors 30, and wherein a second subset of pixels 2 includes red LEDs serving as sensors 30. The blue / green LEDs and red LEDs serving as sensors 30 may also be formed in the same pixel 2. Since both the emitter 20 and the sensor 30 are implemented as (micro)LEDs, they can be manufactured according to a common manufacturing process.

[0084] Figure 3 Another embodiment of pixel 2 in display device 1 is shown. For example, in Figure 2 a and Figure 2 In implementation b, pixel 2 is formed as RGB pixel 2. Pixels 2 are arranged adjacent to each other. Figure 3 Implementation methods and basis Figure 2 a and Figure 2 The difference in implementation b is that the sensor 30 is formed as a photodiode, particularly a miniature photodiode. The sensor 30 can be a discrete miniature photodiode, manufactured similarly to the emitter 20, and then mass-produced and transferred onto the display backplane or flexible plane. This means that the sensor is arranged on the main surface of the substrate 1, and the emitter 20 is also arranged thereon.

[0085] Figure 4 It shows the relationship with Figure 3 The implementation of the display device 1 is similar to that of the pixel 2 in the display device 1. Here, the sensor 30 is formed as a photodiode embedded in a substrate 10 on which the emitter 20 is disposed. For a silicon backplane as the substrate, the sensor can be directly embedded in the backplane including the readout IC. The miniature photodiode can be based on silicon, but other materials are also possible. The size of the photodiode sensor 30 can be similar to the size of the emitter 20, such as... Figure 3 and Figure 4 As shown in the figure.

[0086] exist Figure 5 a and Figure 5 Figure b illustrates another embodiment of the display device 1. The display device 1 includes a substrate 10. A transmitter 20 and a sensor 30 are disposed on the main surface 12 of the substrate 10. For example, Figure 5 a and Figure 5 b illustrates, for example, Figure 2 The corresponding cross-section of pixel 2 in pixel 2. Figure 5 a and Figure 5 In display device 1 of b, the evaluation circuit 40 is integrated into the substrate 10. However, the evaluation circuit 40 may also be arranged in a separate carrier or on which it is electrically connected to the pixel 2 of display device 1. Figure 5 a and Figure 5 The display device 1 of b also includes a transparent cover 60. The cover is arranged vertically above the main surface 12 of the substrate 10, so that the transmitter 20 and the sensor 30 are covered. Figure 5 a shows the light barrier 52 on the left side of the sensor 30, while Figure 5 b shows the corresponding light barrier 52 on the right side of sensor 30. The light barrier 52 is configured to define the viewing angle of the corresponding sensor 30. Therefore, Figure 5 The light barrier 52 of sensor 30 defines the right-oriented viewing angle R, while Figure 5The light barrier 52 defines a left-oriented viewing angle L for the sensor 30. The light barrier 52 is formed as an opaque wall adjacent to the respective sensor 30 and attached to the substrate 10. They may also be attached to the cover 60. The display device 1 may include different groups of pixels 2, wherein a first group of pixels 2 includes sensors 30 having a right-oriented viewing angle R, and a second group of pixels 2 includes sensors 30 having a left-oriented viewing angle L. Sensors having both left-oriented viewing angle L and right-oriented viewing angle R may also be arranged in a common pixel 2. Therefore, the viewing angle of at least one sensor 30 within the display device 1 differs from the viewing angle of at least another sensor 30. In this context, the terms right and left will only be understood as directional indications of a certain orientation of the display device 1. When the display device 1 is rotated, the orientation can be switched or changed to up and down.

[0087] Figure 6 It shows the relationship with Figure 5 The display device 1 shown is similar to the one described above. For better illustration, the substrate 10 and evaluation circuit 40 are omitted. Figure 6 In this configuration, the light barrier 52 is formed as an opaque layer on the side of the cover 60 facing the sensor 30. The light barrier 52 covers a portion of the sensor 30. (As shown...) Figure 6 As shown in the example, the light barrier 52 can cover the sensor area on the right side of the sensor 30, thereby defining a left-oriented viewing angle L. Similarly, a right-oriented viewing angle R can be defined by covering the sensor area on the left side.

[0088] Figure 7 It shows the relationship with Figure 6 A similar display device 1. Here, a light barrier is formed by forming an aperture 50 on the cover 60. The aperture 50 blocks light from the lateral direction, thus defining the forward-oriented viewing angle C of the sensor 30. Therefore, by utilizing blocking structures such as the light barrier 52 and the aperture 50, the sensitivity of the sensor 30 can be directed in a specific direction to allow spatial tracking of an approaching object 100.

[0089] exist Figure 8 a to Figure 8 In example c, the different viewing angles L, R, and C of sensor 30 are defined by means of microlenses 54 on or integrated into cover 60. That is, microlenses 54 are assigned to the respective sensors 30, wherein, in the lateral direction, microlenses 54 are aligned with sensors 30. Microlenses 54 may be centrally positioned above sensors 30 to define a forward-oriented viewing angle C (see [reference needed]). Figure 8 a). The microlens 54 can also be arranged offset above the sensor 30 to define a left-oriented viewing angle L or a right-oriented viewing angle R. Figure 8 b and Figure 8c). The microlens 54 in cover 60 can be formed as a wafer-level optical device.

[0090] Using the optical elements 50, 52, and 54 mentioned above, the display device 1 may include an array of pixels 2, wherein, for example, each second pixel 2 includes a left-viewing sensor 30, and each other pixel 2 includes a right-viewing sensor 30 to form a checkerboard pattern, such as... Figure 9 As shown in the diagram. However, pixel 2 may also include a front-view sensor 30 or a top-view sensor 30.

[0091] The display device 1 shown above can operate as follows: light is emitted by the emitter 20. Additionally, light is sensed by the sensor 30. The sensed light can be ambient light and / or backscattered display light. Furthermore, the proximity of an object 100 above the display device 1 can be assessed based on the sensed light.

[0092] Figure 10 An exemplary method of operation for evaluating the distance to object 100 is shown, specifically, if multiple right-view pixels and left-view pixels 2 are uniformly distributed throughout the entire display screen, a right-view image sensor and a left-view image sensor are obtained. If object 100 is located above display device 1, ambient light is blocked by object 100. Therefore, the image sensors can generate a shadow image. The first instance of generating an image using the left-view sensor 30 (a left-oriented viewpoint). And a second instance of generating an image using the right-view sensor 30 (a right-oriented viewpoint). Depending on the distance from object 100 to the display device, such as display cover 60, in the first instance of the image With the second instance of the image There is a shift . Figure 10 The diagram illustrates the cases at three different distances d1 to d3 for object 100. At distance d3 (far distance), in the first instance... With the second example Image shift exists At a distance d2 (medium distance), the image shift disappears. At a distance d1 (close distance), in the first instance... With the second example Image shift exists Therefore, distance information can be extracted by analyzing two images. Thus, each sensor 30 can be equipped with a micro-optical element that divides the multiple sensors 30 into left-viewing and right-viewing elements. The image shift detected between the right-viewing and left-viewing images can then be used. This determines the distance to object 100. This process is similar to phase-detection autofocus in a camera device.

[0093] The brightness of the light emitted by transmitter 20 can be adjusted using pulse width modulation (PWM), such as... Figure 11 As shown, the brightness can be adjusted individually for each of the transmitters 20, specifically the red LED 20-1, green LED 20-2, and blue LED 20-3. However, the on and off states of the LEDs can be synchronized, resulting in a common on-state phase and a common off-state phase. In other words, the PWM frequency f can be the same for all transmitters 20, as shown. Figure 11 As shown in the diagram. To detect backscattered display light from an approaching object 100, a window TD locked to the PWM cycle is detected, in which the display is on. To detect ambient light passing around the object 100 approaching the display, a time frame TA locked to when the display is off is detected. The on / off state of the display is given by the pulse width modulation frequency and duty cycle. Having a dedicated display light detection window TD and a dedicated ambient light sensing window TA can refer to the PWM-locked detection mode of the display device 1. Alternatively, light sensing is performed continuously during pulse width modulation, and the sensed light is evaluated by filtering the detection signal in the frequency space. Therefore, sensed ambient light and sensed display light can be distinguished.

[0094] exist Figure 12 and Figure 13 The image shows the sensing of ambient light and the sensing of display light. Object 100 is located above display device 1; only the cover 60 of display device 1 is shown. Figure 12 On the left side, display device 1 is in ambient light sensing mode (AL), i.e., display light is off. Object 100 blocks ambient light 100, causing sensor 30 to generate a shadow image SH. In other words, sensor 30 senses a reduction in intensity due to object 100 blocking ambient light AL. Furthermore, a first detection signal from evaluation circuit 40 using sensor data indicates that object 100 is near display device 1. Figure 12 On the right side, display device 1 is in a mode that senses backscattered display light DL. The closer object 100 is, the higher the intensity of the backscattered display light DL. Furthermore, the second detection signal of evaluation circuit 40 indicates that object 100 is near display device 1. Object 100 can be, for example, a user's hand or finger at a distance d from the display device. Figure 13 As shown in the figure.

[0095] Possibly, the evaluation circuit 40 calculates a differential signal that results in high contrast at the edges of the object 100 based on the first and second detection signals. Such differential lock detection... Figure 14 As shown in the image. Figure 14 a shows that it can be used with Figure 13 The shadow image SH corresponding to the fingertip in the image. Figure 14 b shows that it can be used with Figure 13 The image shows the backscattered light DL corresponding to the fingertip. Figure 14 c shows a differential image illustrating the contours of a fingertip. By sensing backscattered display light and ambient light in shadow, fingertips approaching (1 mm to 20 mm) from the display surface can be detected. This achieves so-called hover detection, which is non-contact finger tracking of one or more fingers.

[0096] In addition to (such as) Figure 12 and Figure 13 (in) by evaluating the intensity of the sensed display light reflected by object 100 or (e.g.) Figure 10 In addition to evaluating the distance of the object 100 by assessing the image displacement captured by at least two sets of sensors 30 with different perspectives L, R, C, the relative distance change in continuous tracking can also be obtained by assessing the shape and size changes of images captured by multiple sensors 30.

[0097] As mentioned above, at least one sensor (30) can be implemented as an LED, particularly a microLED, which is biased for sensing photocurrent. It has been found that microLEDs emitting red, green, and blue light can achieve external quantum efficiency (EQE) values ​​exceeding 20% ​​under reverse bias or zero bias, depending on the wavelength to be detected. This is in Figure 15 The image shows a micro LED as a wavelength. The external quantum efficiency is a function of the signal. It can be seen that the blue (B) and green (G) micro-LEDs cover a wavelength range from approximately 350 nm to 500 nm, while the red (R) micro-LEDs cover a wavelength range from approximately 450 nm to 650 nm. Therefore, the display device 1 can use both the red micro-LEDs and the blue / green micro-LEDs as sensors 30 to cover the entire visible spectrum.

[0098] For the purpose of familiarizing the reader with the novel aspects of the concept, embodiments of the display device disclosed herein and methods of operating and manufacturing the display device have been discussed. Although preferred embodiments have been shown and described, many changes, modifications, equivalents, and substitutions of the disclosed concepts can be made by those skilled in the art without unnecessarily departing from the scope of the claims.

[0099] It will be understood that this disclosure is not limited to the disclosed embodiments and those specifically shown and described above. Rather, features that can be advantageously combined in separate dependent claims or set forth in the specification may be included. Furthermore, the scope of this disclosure includes variations and modifications that will be apparent to those skilled in the art and fall within the scope of the appended claims.

[0100] The term "comprising," as long as it is used in the claims or the specification, does not exclude other elements or steps of the corresponding feature or process. When the terms "a" or "an" are used in conjunction with a feature, they do not exclude a plurality of such features. Furthermore, any reference numerals in the claims should not be construed as limiting the scope.

[0101] This patent application claims priority to German patent application 102023125786.2, the disclosure of which is incorporated herein by reference.

[0102] Figure Labels

[0103] 1 Display device

[0104] 2 pixels

[0105] 10 substrates

[0106] 12 main surfaces

[0107] 20 transmitters

[0108] 20-1 First Launcher

[0109] 20-2 Second Launcher

[0110] 20-3 Third Launcher

[0111] 30 sensors

[0112] 30-1 sensor

[0113] 30-2 sensor

[0114] 40 Evaluation Circuit

[0115] 50 aperture

[0116] 52 light barriers

[0117] 54 microlenses

[0118] 60 caps

[0119] 100 objects

[0120] AL ambient light

[0121] DL Display Light

[0122] d1-d3 distance

[0123] L, R, C perspectives

[0124] SH shadow image

[0125] TD display light detection window

[0126] TA Ambient Light Detection Window

[0127] shift

Claims

1. A display device (1), comprising: - Substrate (10), the substrate (10) includes a main surface (12). - A plurality of emitters (20) are arranged in pixels (2) on the main surface (12) of the substrate (10), wherein each emitter (20) includes a light-emitting diode (LED) configured to emit light during operation. - A sensor (30) in at least one pixel (2), said sensor (30) being configured to sense light during operation. - At least one evaluation circuit (40) is configured to: evaluate the proximity of an object (100) above the display device (1) based on the light sensed by the sensor (30) and determine the distance between the object (100) and the display device (1).

2. The display device (1) according to the preceding claim, wherein, Each transmitter (20) is formed by miniature LEDs.

3. The display device (1) according to any one of the preceding claims, wherein, The pixel (2) is formed as an RGB pixel (2), in which a first emitter (20-1) configured to emit red light, a second emitter (20-2) configured to emit green light and a third emitter (30-3) configured to emit blue light are arranged.

4. The display device (1) according to any one of the preceding claims, wherein, The sensor (30) is formed as a photodiode, wherein the photodiode is embedded in the substrate (10) or arranged on the main surface (12) of the substrate (10) adjacent to the transmitter (20).

5. The display device (1) according to any one of claims 1 to 3, wherein, The sensor (30) is implemented as an LED, particularly a micro LED, which is arranged adjacent to the emitter (20) on the main surface (12) of the substrate (10) and configured to be biased for sensing photocurrent.

6. The display device (1) according to the preceding claim, wherein, The transmitter (20) and the sensor (30) are manufactured according to a common manufacturing process.

7. The display device (1) according to any one of the preceding claims includes a plurality of sensors (30) configured to sense light during operation, wherein, The sensors (30) are distributed throughout the display screen in the corresponding pixels (2) of the display device (1).

8. The display device (1) according to the preceding claim, wherein, The viewing angle (L, R, C) of at least one sensor (30) is different from the viewing angle (L, R, C) of at least another sensor (30) in the display device (1).

9. The display device (1) according to any one of the preceding claims further includes an aperture (50) and / or a light barrier (52) and / or a microlens (54) assigned to a respective sensor (30), the aperture (50), the light barrier (52) and the microlens (54) being configured to define the viewing angle (L, R, C) of the respective sensor (30).

10. The display device (1) according to the preceding claim further includes a transparent cover (60) covering the pixels (2), wherein, The light barrier (52) and / or the aperture (50) and / or the microlens (54) are constructed on the cover (60).

11. The display device (1) according to claim 9, wherein, The light barrier (52) is formed as a wall, which is attached to the substrate (10) adjacent to the corresponding sensor (30).

12. The display device (1) according to any one of the preceding claims, wherein, The evaluation circuit (40) is configured to generate a first detection signal using ambient light sensed by the sensor (30) that is obscured by the object (100) and / or to generate a second detection signal using light sensed by the sensor (30) that is emitted by the transmitter (20) and reflected by the object (100).

13. The display device (1) according to the preceding claim, wherein, The evaluation circuit (40) is configured to calculate a differential signal based on the first detection signal and the second detection signal.

14. A method for operating a display device (1), wherein, The display device (1) includes a plurality of emitters (20) arranged in pixels (2) on the main surface (12) of a substrate (10), a sensor (30) in at least one pixel (2), and at least one evaluation circuit (40), the method comprising: - Light is emitted by the emitter (20), wherein each emitter (20) includes a light-emitting diode (LED). - Light is sensed by the sensor (30), - The evaluation circuit (40) evaluates the proximity of the object (100) above the display device (1) based on the sensed light and determines the distance between the object (100) and the display device (1).

15. The method according to the preceding claims, further comprising: The brightness of the emitted light is adjusted by pulse width modulation.

16. The method according to the preceding claim, wherein, The sensing light includes: - When the transmitter (20) is in the off state during pulse width modulation, sense ambient light, and / or - When the transmitter (20) is in the on state during pulse width modulation, it senses the reflected light.

17. The method according to claim 15, wherein, The sensing light is continuously performed during the pulse width modulation, and the sensed light is evaluated by filtering the detection signal in the frequency space.

18. The method according to the preceding claim further comprises evaluating the distance between the object (100) and the display device, wherein, The distance is determined in the following way: - Evaluate the intensity of the sensed light reflected by the object (100), and / or - Evaluate image shift captured by at least two sets of sensors (30) with different viewpoints (L, R, C), and / or - Evaluate the shape and size changes of images of objects (100) captured by multiple sensors (30).

19. A method for manufacturing a display device (1), the method comprising: - Provide substrate (10). - A plurality of emitters (20) are mounted on the main surface (12) of the substrate (10), wherein the emitters (20) are arranged in pixels (2), and each emitter (20) includes a light-emitting diode (LED) configured to emit light during operation. - A sensor (30) is formed in at least one pixel (2), the sensor (30) being configured to sense light during operation. - Provide at least one evaluation circuit (40) configured to: evaluate the proximity of an object (100) above the display device (1) based on the light sensed by the sensor (30) and determine the distance between the object (100) and the display device (1).

20. The method according to the preceding claim, wherein, Forming the sensor (30) includes: - Embed the photodiode in the substrate (10), or - The photodiode is mounted adjacent to the emitter (20) on the main surface (12) of the substrate (10), or - An LED is mounted adjacent to the emitter (20) on the main surface (12) of the substrate (10) and the LED is biased for sensing photocurrent.

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