Display stack with millimeter-wave antenna functionality

A display stack with millimeter-wave antenna functionality comprising a plurality of adjoining layers, the layers comprising at least a cover layer, a touch sensor panel layer comprising a touch sensor arrangement, and a display panel layer. The touch sensor panel layer comprises a first sensor line grid pattern and a second sensor line grid pattern, the first sensor line grid pattern comprising a plurality of continuous first sensor lines, the second sensor line grid pattern comprising a plurality of continuous second sensor lines. At least a part of the first sensor lines and the second sensor lines are configured to function as radiators for the millimeter wave antenna functionality. This allows providing the millimeter wave antenna in the touch sensor panel structure without the antenna and the touch sensor panel interfering with each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/EP2020/052160, filed on Jan. 29, 2020, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to a display stack with millimeter-wave antenna functionality, and an electronic device comprising such a display stack.

BACKGROUND

Conventionally, the antennas of an electronic device are arranged outside of the display, such that the display does not interfere with the efficiency and frequency bandwidth of the antenna. However, the movement towards higher and higher display to body ratio of the electronic device, makes the space available for the antennas very limited, forcing either the size of the antennas to be significantly reduced, and its performance impaired, or a large part of the display to be inactive.

Furthermore, electronic devices need to support more and more radio signal technology such as 2G/3G/4G radio. For coming 5G radio technology, high throughput is a one of the properties which need to be fulfilled, requiring large bandwidths, Multiple Input Multiple Output (MIMO), and efficient modulation schemes. The frequency bands will be expanded to cover frequencies up to 6 GHz, as well as millimeter wave bands including 24.2-29.5 GHz and 37-40 GHz, thus requiring the addition of a number of new wide-band antennas in addition to the existing antennas. Millimeter wave antenna systems are required for gigabit-level bandwidths, but the operation distance is limited when compared to sub-6-gigahertz radio systems.

Prior art solutions utilize regions of the touch sensor panel layer to accommodate the millimeter wave antenna. In these regions, the touch panel sensor lines are cut off, which affects the touch function. The regions that comprise cut off sensor lines will have no touch function at all or with decreased performance, leaving the display non-user-friendly.

SUMMARY

It is an object to provide an improved display stack with millimeter-wave antenna functionality. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a display stack with millimeter-wave antenna functionality comprising a plurality of adjoining layers, the layers comprising at least a cover layer, a touch sensor panel layer comprising a touch sensor arrangement, a display panel layer, the touch sensor panel layer comprising a first sensor line grid pattern and a second sensor line grid pattern, the first sensor line grid pattern comprising a plurality of continuous first sensor lines, the second sensor line grid pattern comprising a plurality of continuous second sensor lines, at least a part of the first sensor lines and the second sensor lines being configured to function as radiators for the millimeter wave antenna functionality.

Such a display stack allows the touch sensor arrangement to be reused as millimeter wave antenna radiators without adding any additional parts to the touch sensor panel layer, and without decreasing the overall transmittance of display side of an electronic device due to adding extra antennas. This allows providing the millimeter wave antenna in the touch sensor panel structure without the antenna and the touch sensor panel interfering with each other.

In an embodiment, the first sensor lines form transmission lines of the touch sensor arrangement, the transmission lines extending substantially in a first direction, and the second sensor lines form receiver lines of the touch sensor arrangement, the receiver lines extending substantially in a second direction, the second direction extending at an angle>0° to the first direction. This allows the touch sensor arrangement to accommodate the millimeter wave antenna without affecting the touch function.

In an embodiment, the first sensor lines extend at least partially nonlinearly in the first direction such that distances between adjacent first sensor lines vary periodically along the first direction. By keeping the original touch sensor arrangement elements the same, except for some of the lines in the antenna area having reduced widths, there will be no significant loss in touch sensitivity while still providing good isolation to the millimeter wave signals.

In an embodiment, a nonlinear section of the first sensor line is at least diagonal, comprising at least two sections extending at an angle to the first direction, the angle preferably being 45°. The shape of the transmission line is optimized to achieve the best touch sensor panel performance and the best antenna performance simultaneously.

In an embodiment, the first sensor line grid pattern and a second sensor line grid pattern form a single layer conductive mesh.

In an embodiment, each second sensor line comprises a plurality of individual receiver units, two adjacent receiver units of one second sensor line being interconnected by a conductive bridge. The bridge will work as a direct link for touch sensor panel signals between different receiver units, but block the millimeter wave signals from passing.

In an embodiment, each receiver unit of one second sensor line is connected to a feed line.

In an embodiment, the feed line comprises a conductive or inductive coupling to the receiver unit. By not connecting the feed line directly to the receiver unit, but maintaining a small gap therebetween, there will be a feed for the millimeter wave antenna, while still avoiding interference between touch sensor panel signals and millimeter wave signals, since the touch sensor panel signals are usually of much lower frequencies.

In an embodiment, the receiver unit has a polygonal shape, the polygon being symmetrical in the first direction and the second direction. The shape of the receiver unit is optimized to achieve the best touch sensor panel performance and the best antenna performance simultaneously.

In an embodiment, the receiver unit is at least quadrilateral, comprising at least two sections extending at an angle to the first direction and the second direction, the angle preferably being 45°, facilitating a pattern which is relatively easy to manufacture yet still allows as much effective areas as possible for the touch function as well as the antenna radiators.

In an embodiment, the first sensor line grid pattern and the second sensor line grid pattern form a dual layer conductive mesh, the first sensor line grid pattern and the second sensor line grid pattern being separated by an insulation substrate layer in a third direction perpendicular to the first direction and the second direction.

In an embodiment, the second sensor line grid pattern is arranged adjacent the cover layer, and the first sensor line grid pattern is arranged adjacent the display panel layer.

In an embodiment, the second sensor lines extend at least partially nonlinearly in the second direction such that distances between adjacent second sensor lines vary periodically along the second direction. By keeping the original touch sensor arrangement elements the same, except for some of the lines in the antenna area having reduced widths, there will be no significant loss in touch sensitivity while still providing good isolation to the millimeter wave signals.

In an embodiment, a non-linear section of the second sensor line is at least diagonal, comprising at least two sections extending at an angle to the second direction, the angle preferably being 45°.

In an embodiment, the non-linear sections of the first sensor lines comprise dummy areas isolating adjacent first sensor lines from each other, and/or the non-linear sections of the second sensor lines comprise dummy areas isolating adjacent second sensor lines from each other, the dummy area(s) being configured to accommodate millimeter wave antenna elements, enhancing the radiation efficiency.

In an embodiment, the display stack does not comprise a separate millimeter-wave antenna layer. Any additional antenna layers will cause a lower light transmittance level since the additional antenna layer will give a light transmittance level lower than 100%. A lower light transmittance level in the display stack will lead to either a reduction in luminance level or higher power consumption, both of which are critical disadvantages in the eyes of a user.

In an embodiment, the display stack further comprises a parasitic or coupled radiator layer arranged between the cover layer and the touch sensor panel layer, the radiator layer comprising transparent conductive mesh, enhancing the antenna performance by extending the working bandwidth, increasing the radiating gain, etc.

In an embodiment, a section of the cover layer, facing the touch sensor panel layer, is configured to accommodate the radiators of the millimeter wave antenna functionality, reducing the necessary height of the display stack.

According to a second aspect, there is provided an electronic device comprising a display stack according to the above.

This and other aspects will be apparent from the embodiments described below.

DETAILED DESCRIPTION

FIGS.1aand1bshow a display stack1with millimeter-wave antenna functionality. The display stack1comprises a plurality of adjoining layers, at least a cover layer2, a touch sensor panel layer3comprising a touch sensor arrangement (not shown), and a display panel layer4.

The touch sensor panel layer3comprises a first sensor line grid pattern5and a second sensor line grid pattern6, shown in more detail inFIGS.2to5b. The first sensor line grid pattern5comprises a plurality of continuous first sensor lines5a, and the second sensor line grid pattern6comprises a plurality of continuous second sensor lines6a. By continuous means that each first sensor lines5aand each second sensor lines6ais integral and uninterrupted as it extends across the first sensor line grid pattern5and a second sensor line grid pattern6, respectively. At least a part of the first sensor lines5aand the second sensor lines6aare configured to function as radiators for the millimeter wave antenna functionality.

The first sensor lines5aform the transmission lines of the touch sensor arrangement and extend substantially in a first direction D1. The second sensor lines6aform the receiver lines of the touch sensor arrangement and extend substantially in a second direction D2. The second direction D2extends at an angle>0° to the first direction D1, the angle being, for example, 90° as indicated in the Figs.

The first sensor lines5amay extend at least partially nonlinearly in the first direction D1such that distances between adjacent first sensor lines5avary periodically along the first direction D1.

The nonlinear section5bof the first sensor line5amay be at least diagonal, i.e., comprise at least two sections extending at an angle to each other and to the first direction D1, the angle preferably being 45° as shown inFIGS.2,4a, and5a. The nonlinear section5bmay also comprise three sections extending at angles to each other. As shown inFIG.3, two sections may be arranged such that they extend at a 45° angle to the first direction D1, and are separated by a third section extending in parallel with the first direction D1. The nonlinear section5bmay also have any other suitable, polygonal shape.

The first sensor line grid pattern5and a second sensor line grid pattern6may be arranged such that they form a single layer conductive mesh, as shown inFIGS.2and3.

In such an embodiment, each second sensor line6amay comprise a plurality of individual receiver units7. Two adjacent receiver units7of one single second sensor line6aare interconnected by a conductive bridge8, as shown inFIGS.2,3, and5a.

The receiver unit7may have a polygonal shape, the polygon being symmetrical in both the first direction D1and the second direction D2. The receiver unit7may be at least quadrilateral, comprising at least two sections extending at an angle to the first direction D1and the second direction D2, the angle preferably being 45°. The receiver unit7may also be hexagonal, such that four sections are be arranged at 45° angles to the first direction D1, and two sections extend in parallel with the first direction D1. The receiver unit7may also have any other suitable, polygonal shape.

Each receiver unit7of one single second sensor line e6amay be connected to a feed line9. The feed line9may comprise a conductive or inductive coupling to the receiver unit7.

The first sensor line grid pattern5and the second sensor line grid pattern6may also form a dual layer conductive mesh, as shown inFIGS.4a,4b,5a, and5b. In such an embodiment, the first sensor line grid pattern5and the second sensor line grid pattern6are separated by an insulation substrate layer11in a third direction D3perpendicular to the first direction D1and the second direction D2, as shown inFIG.4b. The insulation substrate layer11may comprise of cyclic olefin polymer (COP) film.

The second sensor line grid pattern6may be arranged adjacent the cover layer2, and the first sensor line grid pattern5arranged adjacent the display panel layer4. The second sensor lines6amay extend at least partially nonlinearly in the second direction D2such that distances between adjacent second sensor lines6avary periodically along the second direction D2.

The non-linear section6bof the second sensor line6amay be at least diagonal, i.e., comprise at least two sections extending at an angle to each other and to the second direction D2, the angle preferably being 45° as shown inFIG.5b. The nonlinear section6bmay also comprise three sections extending at angles to each other. As shown inFIG.4a, two sections may be arranged such that they extend at a 45° angle to the second direction D2, and are separated by a third section extending in parallel with the second direction D2. The nonlinear section6bmay also have any other suitable, polygonal shape.

As shown inFIG.5b, the non-linear sections5bof the first sensor lines5amay comprise dummy areas12isolating adjacent first sensor lines5afrom each other. Correspondingly, the non-linear sections6bof the second sensor lines6amay comprise dummy areas12isolating adjacent second sensor lines6afrom each other. The dummy areas12are configured to accommodate millimeter wave antenna elements.

In one embodiment, the display stack1does not comprise a separate millimeter-wave antenna layer. Any additional antenna layers, other than the touch sensor panel layer3, will cause a lower light transmittance level since the additional antenna layer will give a light transmittance level lower than 100%. A lower light transmittance level in the display stack1will lead to either a reduction in luminance level or higher power consumption, both of which are critical disadvantages in the eyes of a user.

The display stack1may further comprise a parasitic or coupled radiator layer10arranged between the cover layer2and the touch sensor panel layer3, as shown inFIG.1b. The radiator layer10comprises transparent conductive mesh. The radiator layer10may also be integrated with a layer arranged above the touch sensor panel layer, including but not restricted to the bottom surface of the cover layer.

A section of the cover layer2, facing the touch sensor panel layer3, may be configured to accommodate the radiators of the millimeter wave antenna functionality (not shown).

The present invention also relates to an electronic device comprising a display stack1according to the above. The electronic device may be, for example, a smartphone, a laptop computer, or a tablet computer.

The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.