Patent Description:
Displays of devices like smartphones tend to occupy the complete front side of the device such that optical sensors are located under the display. The transparency of conventional displays is limited. As the light needs to pass the display, the optical sensors suffer from this trend. Current display technologies need to sacrifice display quality (e.g. brightness and/or resolution) for increased display transparency.

Documents <CIT> and <CIT> propose displays comprising a first display area provided with Organic Light Emitting Diodes (OLEDs) and a second display provided with micro Light Emitting Diodes (LEDs). Neither document <CIT> nor document <CIT> discloses the following features of independent claim <NUM>:.

Hence, there may be a demand for improved light guidance through displays.

The demand may be satisfied by the subject matter of the appended claims.

An example relates to an electronic device. The electronic device comprises a display device configured to display an optical image on a front side of the display device. Further, the electronic device comprises at least one ToF sensor configured to measure infrared light received from a scene in front of the front side of the display device. The display device comprises a first display region using a first display technology and exhibiting a first transmissivity for electromagnetic radiation. The electromagnetic radiation comprises the infrared light. The display device further comprises a second display region using a second display technology and exhibiting a second transmissivity for the electromagnetic radiation. The first transmissivity is higher than the second transmissivity. The at least one sensor is arranged on a back side of the display device and faces the first display region. The first display region comprises at least one light-emitting element configured to emit the infrared light for illuminating the scene.

When two elements A and B are combined using an "or", this is to be understood as disclosing all possible combinations, i.e. only A, only B as well as A and B, unless expressly defined otherwise in the individual case.

<FIG> illustrates part of an electronic device <NUM> such as, e.g., a smartphone, a tablet-computer or a laptop-computer. However, it is to be noted that the electronic device <NUM> may be any other electronic device as well.

The electronic device <NUM> comprises a display device <NUM> configured to display an optical image on a front side of the display device <NUM>. The front side <NUM> of the display device <NUM> is the side of the display device <NUM> that can be seen by a user of the electronic device <NUM>. The display device <NUM> may cover (substantially) the entire front surface of the electronic device <NUM> as illustrated in <FIG>. In other examples, the display device <NUM> may cover only a fraction of the electronic device <NUM>'s front surface.

Further, the electronic device <NUM> comprises at least one ToF sensor <NUM> (for direct and/or indirect ToF sensing) configured to infrared light (i.e. a wavelength of the light is between approx. <NUM> and approx. <NUM>) received from a scene in front of the front side of the display device <NUM>. In the example of <FIG>, one ToF sensor <NUM> is illustrated. However, the electronic device <NUM> may optionally comprise plural sensors. The at least one ToF sensor <NUM> is arranged within the electronic device <NUM> at a back side of the display device <NUM>. In other words, the display device <NUM> is arranged between the at least one ToF sensor <NUM> and the scene. As a consequence, the infrared light from the scene needs to transmit through the display device <NUM> in order to reach the ToF sensor <NUM>.

The display device <NUM> comprises a first display region <NUM> using a first display technology. The display device <NUM> further comprises a second display region <NUM> using a second display technology. In other words, the first display region <NUM> and the second display region <NUM> are based on different display technologies.

The first display region <NUM> exhibits a first transmissivity for the electromagnetic radiation. The second display region <NUM> exhibits a second transmissivity for the electromagnetic radiation. The first transmissivity is higher than the second transmissivity. The electromagnetic radiation comprises the infrared light.

The at least one ToF sensor <NUM> faces the first display region <NUM> with increased transparency for the electromagnetic radiation. In other words, the at least one ToF sensor <NUM> is arranged on the back side of the display device <NUM> at a position of the first display region <NUM>.

As the at least one ToF sensor <NUM> is arranged behind the first display region <NUM> with increased transparency for the electromagnetic radiation, a higher fraction of the infrared light from the scene can reach the at least one ToF sensor <NUM> compared to an arrangement of the sensor behind the second display region <NUM>. As a consequence, impairment of the at least one ToF sensor <NUM> by the display device <NUM> may be significantly reduced compared to conventional display structure for under-display sensors.

In order to achieve the increased transparency for the electromagnetic radiation in the first display region <NUM>, a substrate (not illustrated) of the display device <NUM> may, e.g., be covered in the first display region <NUM> per unit area to a lesser extent with electronic circuitry of the display device <NUM> than in the second display region <NUM>. For example, less electronic circuitry of the display device may be arranged in the first display region <NUM> compared to the second display region <NUM>. Alternatively or additionally, electronic circuitry of a smaller form factor may be arranged in the first display region <NUM> compared to the second display region <NUM>. For example, the second display region <NUM> may be based on a LED display technology, an OLED display technology or a Liquid Crystal Display (LCD) technology. The first display region <NUM> may, e.g., be based on a micro LED display technology. In other words, the first display technology may use micro LEDs, whereas the second display technology may use OLEDs. As micro LEDs are smaller in size than OLEDs, the substrate of the display device <NUM> is covered in the first display region <NUM> per unit area to a lesser extent with LEDs than in the second display region <NUM>.

Speaking more general, the first display region <NUM> comprises a plurality of first light-emitting elements for displaying a first part of the optical image on the front side of the display device <NUM>, and the second display region <NUM> comprises a plurality of second light-emitting elements for displaying a second part of the optical image on the front side of the display device <NUM>. The first light-emitting elements are of smaller individual size than the second light-emitting elements. Each of the first light-emitting elements may, e.g., comprise at least one respective micro LED, and each of the second light-emitting elements may, e.g., comprise at least one respective OLED. For example, each of the first light-emitting elements may comprise at least three micro LEDs each configured to selectively emit different ones of red light, green light and blue light. Similarly, each of the second light-emitting elements may comprise at least three OLEDs each configured to selectively emit different ones of red light, green light and blue light. Accordingly, distances between neighboring ones of the plurality of second light-emitting elements in the second display region <NUM> are smaller than distances between neighboring ones of the plurality of first light-emitting elements in the first display region <NUM>. Each of the first and second light-emitting elements may be configured to selectively emit red, green and/or blue light - either directly (e.g. by comprising corresponding micro LEDs or OLEDs for the different light colors) or indirectly (e.g. using one or more light conversion elements for converting the light emitted by one or more micro LEDs or OLEDs to red, green or blue light).

The light-emitting elements (circuitries, devices) in the first display region <NUM> and the second display region <NUM> may be arranged in an array as pixels for displaying the optical image. A pixel density of the first display region may be equal to a pixel density of the second display region. In other words, a display resolution of the display device <NUM> need not be reduced in the first display region <NUM> compared to the second display region <NUM> for achieving the increased transparency for the electromagnetic radiation in the first display region <NUM>. In other words, a number of the first light-emitting elements per unit area in the first display region <NUM> is equal to a number of the second light-emitting elements per unit area in the second display region <NUM>.

If electronic circuitry of a smaller form factor is arranged in the first display region <NUM> compared to the second display region <NUM>, the pixel density of the first display region may even be greater than to the pixel density of the second display region while still achieving an increased transparency for the electromagnetic radiation in the first display region <NUM> compared to the second display region <NUM> (e.g. when using micro LEDs in the first display region <NUM> and OLEDs in the second display region <NUM>). In other words, the number of the first light-emitting elements per unit area in the first display region <NUM> may be greater than the number of the second light-emitting elements per unit area in the second display region <NUM> while still achieving an increased transparency for the electromagnetic radiation in the first display region <NUM> compared to the second display region <NUM>.

According to examples, the electronic circuitry of the first display region <NUM> may be formed on a same substrate layer of the display device <NUM> as the electronic circuitry of the second display region <NUM> (e.g. in a thin-film transistor layer or another layer of the display device <NUM>). Alternatively, the electronic circuitry of the first display region <NUM> and the electronic circuitry of the second display region <NUM> may be formed on different substrate layers of the display device <NUM> (e.g. in different thin-film transistor layers or different other layers of the display device <NUM>). In other words, the display device <NUM> may support different display technologies on the same substrate.

At the border between the display technologies, there could be an overlap region featuring both technologies in order to further mitigate a potentially visible edge between the different display technologies. In other words, the display device <NUM> may optionally comprise an additional third display region (not illustrated) which is formed between the first display region <NUM> and the second display region <NUM>. As indicated above, the third display region comprises a mixed arrangement of the first light-emitting elements and the second light-emitting elements. For example, micro LEDs forming the first light-emitting elements may be integrated/arranged between OLEDs forming the second light-emitting elements.

The ToF sensor <NUM> may, e.g., comprise a Photonic Mixer Device (PMD) or a Charge-Coupled Device (CCD) for measuring the light. Accordingly, the ToF sensor <NUM> may comprise processing circuitry configured to determine, based on the measured light from the scene, a distance of the electronic device <NUM> to at least one object in the scene.

The first display region <NUM> comprises at least one further light-emitting element (circuitry, device) configured to emit the infrared light for illuminating the scene. For example, the at least one further light-emitting element may comprise/be a micro LED configured to emit the infrared light. In other examples, the at least one further light-emitting element may comprise a Vertical-Cavity Surface-Emitting Laser (VCSEL) or any other type of laser diode that is configured to emit the infrared light. In other words, the first display region <NUM> may contain not only RGB pixels, but also one or more infrared (micro) LEDs or infrared VCSELs forming an illumination unit (e.g. if the at least one optical sensor <NUM> is a ToF sensor). For example, some of the RGB micro LEDs of the first display region <NUM> may be replaced with infrared (micro) LEDs or infrared VCSELs. Alternatively, the infrared (micro) LEDs or infrared VCSELs may be placed between the RGB micro LEDs of the first display region <NUM>. The driver circuitry for the infrared (micro) LEDs or infrared VCSELs may be integrated in the existing display circuitry for driving the regular e.g. OLEDs or micro LEDs of the display. The at least one further light-emitting element may be configured to selectively emit the infrared light either directly (e.g. by comprising corresponding micro LEDs or VCSELs for the infrared light) or indirectly (e.g. using one or more light conversion elements for converting the light emitted by one or more micro LEDs or VCSELs to infrared light).

The first display region <NUM> may be a coherent (connected) region of the display device <NUM> as illustrated in <FIG> or comprise a plurality of non-coherent (discontinuous) sub-regions. For example, if the electronic device <NUM> comprises a plurality of sensors (the at least one ToF sensor <NUM> being one of the plurality of sensors), the plurality of sensors may be arranged on the back side of the display device <NUM> facing different ones of the plurality of sub-regions. In other words, the plurality of sensors may be arranged on the back side of the display device <NUM> at positions of different ones of the plurality of sub-regions of the first display region <NUM>.

There may be any number of sub-regions of the first display region <NUM>. Any number of sensors or other electronic devices may be arranged underneath of each of the sub-regions.

For example, at least one of the plurality of sensors may be one of a radar sensor and a radio frequency receiver for wireless communication measuring radio waves from the scene.

The electronic device <NUM> may optionally further comprises at least one emitter (not illustrated) configured to emit the radio waves. For example, the at least one emitter may be arranged on the back side of the display device <NUM> and face the first display region <NUM>. In other words, the at least one emitter may be arranged on the back side of the display device <NUM> at a position of the first display region <NUM>. That is, also the at least one emitter may be arranged behind the first display region <NUM> with increased transparency for the electromagnetic radiation.

As the at least one emitter faces the first display region <NUM>, the radio waves pass (substantially) through the first display region <NUM> with increased transparency such that a higher fraction of the radio waves can transmit through the display device <NUM> into the scene. Accordingly, a power of the radio waves may be reduced compared to conventional under-display emitter structures. As a consequence, a power consumption of the at least one emitter may be reduced compared to conventional under-display emitter structures.

For example, if the at least one sensor is a radar sensor measuring radio waves from the scene in front of the front side of the display device <NUM>, the at least one emitter may be configured to emit the radio waves for scanning the scene. In other words, the at least one emitter may be a radar transmitter.

In case the at least one sensor is a radio frequency receiver for wireless communication, the at least one emitter may be configured to emit radio waves and act as a radio frequency transmitter for wireless communication.

Generally speaking, any electronic device, which is impaired by the display technology of the second display region <NUM>, may be located behind the first display region <NUM> with increased transparency.

The display device <NUM> may comprise one or more additional display regions using one or more display technologies different from the first and the second display technologies of the first display region <NUM> and the second display region <NUM>. Transparencies of the one or more additional display regions for the electromagnetic radiation may be different from those of the first display region <NUM> and the second display region <NUM>. Similarly to what is described above, any number of sensors or other electronic devices may be arranged underneath of each of the additional display regions.

A ratio of the first display region <NUM>'s size to the second display region <NUM>'s size may be arbitrary. For example, the size of the first display region <NUM> may be smaller than the size of the second display region <NUM>. However, the proposed technique is not limited thereto.

In the example of <FIG>, the second display region <NUM> fully surrounds the first display region <NUM>. In other words, the first display region <NUM> is fully enclosed by the second display region <NUM>. However, the proposed technique is not limited thereto. The second display region <NUM> may, e.g., only partially surround the first display region <NUM> in some examples. For example, if the first display region <NUM> is arranged at an edge of the electronic device <NUM>'s front surface, only part of the first display region <NUM> may be surrounded by the second display region <NUM>. The other part of the first display region <NUM> may form the part of the edge of the electronic device <NUM>'s front surface.

The first display region <NUM> exhibits a rectangular shape in the example of <FIG>. However, the proposed technique is not limited thereto. In general, the first display region <NUM> and the second display region <NUM> may be of any target (desired) shape. For example, the first display region <NUM> may exhibit a circular or an oval shape according to examples of the present disclosure.

In other words, <FIG> shows an exemplary device where the main display has a "hole", in which a different technology is used to create an area which is more transparent than the remaining display. Below, optical sensors like cameras and ToF sensors are located.

Although not illustrated in <FIG>, the electronic device <NUM> may optionally comprise further circuitry/elements such as, e.g., one or more microphones, one or more loudspeakers, one or more antennas, one or more application processors, one or more radio frequency transmitters and/or receivers for mobile communication, one or more data storages, one or more batteries, etc..

In the above, it was described that the first display region and the second display region are formed on the same substrate. However, the proposed technique is not limited thereto. In alternative examples, two separate displays may be used. This is shown in <FIG> illustrating an alternative display device <NUM>.

The display device <NUM> comprises a first display <NUM> using the first display technology and a second display <NUM> using the second display technology. For example, the first display <NUM> may be a micro LED display and the second display <NUM> may be an OLED display. Accordingly, the first display <NUM> is more transparent for the electromagnetic radiation than the second display <NUM>.

The second display <NUM> extends over the second display region <NUM> of the display device <NUM> similar to what is described above. Further, a recess (notch, gap, opening) <NUM> is formed in the second display <NUM> so that the second display <NUM> does not extend into the first display region <NUM> of the display device <NUM>. The first display <NUM> is arranged on a backside of the second display <NUM> and faces the recess <NUM>. In other words, the first display <NUM> is arranged on the backside of the second display <NUM> at a position of the recess <NUM>.

The recess <NUM> may, e.g., be filled with a transparent material such that the second display <NUM> is visible.

Each of the first display <NUM> and the second display <NUM> is configured to display a respective part of an optical image on its respective front side such that the optical image as a whole is displayed on the front side of the display device <NUM>.

Similar to what is described above, at least one optical sensor <NUM> is placed behind the first display <NUM> (faces the first display <NUM>) to make use of the increased transparency of the first display <NUM>.

Using two separate displays <NUM> and <NUM> may allow to independently develop the first display <NUM> and customize it for the underlying sensor(s). Accordingly, the display technology of the second display <NUM> need not be adapted.

<FIG> illustrates a variation of the electronic device <NUM>. While the second display region <NUM> fully surrounds the first display region <NUM> in the example of <FIG>, the first display region <NUM> fully surrounds the second display region <NUM> in the example of <FIG>. Again, the at least one ToF sensor <NUM> is placed behind the first display region <NUM> with increased transparency. For example, an illuminated edge around the main display <NUM> of the electronic device <NUM> (e.g. a smartphone) may be achieved.

Although not explicitly illustrated in <FIG>, the first display region <NUM> may only partially surround the second display region <NUM> in other examples of the present disclosure. For example, at least part of the second display region <NUM> may extend up to an edge of the electronic device <NUM>'s front surface.

However, similar to what is stated above, the proposed technique is not limited to the shapes of the first display region <NUM> and the second display region <NUM> illustrated in <FIG>. In general, the first display region <NUM> and the second display region <NUM> may be of any target (desired) shape.

The examples as described herein may be summarized as follows:
Some examples relate to an electronic device. The electronic device comprises a display device configured to display an optical image on a front side of the display device. Further, the electronic device comprises at least one sensor configured to measure electromagnetic radiation received from a scene in front of the front side of the display device. The display device comprises a first display region using a first display technology and exhibiting a first transmissivity for the electromagnetic radiation. The display device further comprises a second display region using a second display technology and exhibiting a second transmissivity for the electromagnetic radiation. The first transmissivity is higher than the second transmissivity. The at least one sensor is arranged on a back side of the display device and faces the first display region.

In some examples, a pixel density of the first display region is equal to a pixel density of the second display region.

According to some examples, the first display technology uses micro light emitting diodes, and wherein the second display technology uses organic light emitting diodes.

In some examples, the first display region comprises a plurality of first light-emitting elements for displaying a first part of the optical image on the front side of the display device, wherein the second display region comprises a plurality of second light-emitting elements for displaying a second part of the optical image on the front side of the display device.

According to some examples, the first light-emitting elements are of smaller individual size than the second light-emitting elements.

In some examples, distances between neighboring ones of the plurality of second light-emitting elements in the second display region are smaller than distances between neighboring ones of the plurality of first light-emitting elements in the first display region.

According to some examples, a number of the first light-emitting elements per unit area in the first display region is equal to a number of the second light-emitting elements per unit area in the second display region.

In some examples, each of the first light-emitting elements comprises at least one respective micro light emitting diode, wherein each of the second light-emitting elements comprises at least one respective organic light emitting diode.

According to some examples, the display device comprises a third display region, wherein the third display region comprises a mixed arrangement of the first light-emitting elements and the second light-emitting elements.

In some examples, electronic circuitry of the first display region is formed on a same substrate layer of the display device as electronic circuitry of the second display region.

In alternative examples, electronic circuitry of the first display region and electronic circuitry of the second display region are formed on different substrate layers of the display device.

In further alternative examples, the display device comprises a first display using the first display technology and a second display using the second display technology, wherein the second display extends over the second display region, wherein a recess is formed in the second display so that the second display does not extend into the first display region, and wherein the first display is arranged on a backside of the second display and faces the recess.

According to some examples, the electronic device comprises a plurality of sensors, wherein the first display region comprises a plurality of sub-regions, and wherein the plurality of sensors are arranged on the back side of the display device facing different ones of the plurality of sub-regions.

In some examples, the at least one sensor is an optical sensor, and wherein the electromagnetic radiation comprises light.

According to some examples, the at least one sensor is one of a radar sensor and a radio frequency receiver, and wherein the electromagnetic radiation comprises radio waves.

In some examples, the electronic device further comprises at least one emitter configured to emit the electromagnetic radiation, wherein the at least one emitter is arranged on the back side of the display device and faces the first display region.

According to some examples, the electromagnetic radiation comprises infrared light, wherein the first display region comprises at least one light-emitting element configured to emit the infrared light for illuminating the scene.

In some examples, the first display region at least partially surrounds the second display region.

In alternative examples, second display region at least partially surrounds the first display region.

According to some examples, the electronic device is one of a smartphone, a tablet-computer and a laptop-computer.

Examples of the present disclosure may provide display with multiple pixel technologies for under-display sensors. According to examples, a more transparent display technology is selectively used in the area of a (e.g. smartphone) display where optical sensors and illumination units are located. In other words, a solution for the under-display camera problem is proposed that combines, e.g., micro LED displays with another display technology (e.g. OLED or liquid display) in order to generate a camera window for electronic devices like smartphones with good transparency. For example micro LED displays may allow for increased brightness and smaller pixel sizes of several µm in diameter that may provide increased transparency. Behind the more transparent area of the display, optical or other sensors can be located.

Claim 1:
An electronic device (<NUM>), comprising:
a display device (<NUM>) configured to display an optical image on a front side of the display device (<NUM>); and
at least one Time-of-Flight sensor (<NUM>) configured to measure infrared light received from a scene in front of the front side of the display device (<NUM>),
wherein the display device (<NUM>) comprises a first display region (<NUM>) using a first display technology and exhibiting a first transmissivity for electromagnetic radiation, wherein the electromagnetic radiation comprises the infrared light,
wherein the display device (<NUM>) further comprises a second display region (<NUM>) using a second display technology and exhibiting a second transmissivity for the electromagnetic radiation, the first transmissivity being higher than the second transmissivity,
wherein the at least one sensor (<NUM>) is arranged on a back side of the display device (<NUM>) and faces the first display region (<NUM>), and
wherein the first display region (<NUM>) comprises at least one light-emitting element configured to emit the infrared light for illuminating the scene.