CN112924023B

CN112924023B - Sensor below display screen and method for measuring intensity of external light by using sensor

Info

Publication number: CN112924023B
Application number: CN202110202094.0A
Authority: CN
Inventors: 闵丙日
Original assignee: Hangzhou Xinge Microelectronics Co ltd
Current assignee: Hangzhou Xinge Microelectronics Co ltd
Priority date: 2021-02-23
Filing date: 2021-02-23
Publication date: 2024-08-13
Anticipated expiration: 2041-02-23
Also published as: CN112924023A

Abstract

The invention relates to a sensor below a display screen and a method for measuring the intensity of external light by using the sensor. The sensor below the display screen includes: a light selection layer forming a first light path that passes through the non-polarized light and all the circularly polarized light incident from the display screen and a second light path that passes through the non-polarized light and a part of the circularly polarized light; a first light receiving unit that detects unpolarized light from the display panel, circularly polarized light from the display panel, and circularly polarized light from outside light incident on the display panel, which have passed through the first light path; and a second light receiving unit that detects the unpolarized light from the display screen, the circularly polarized light from the display screen, and the circularly polarized light formed by the external light incident on the display screen, which has passed through the second light path, wherein the intensity of the external light is calculated by an external light calculation formula that takes as input the first detection value detected by the first light receiving unit and the second detection value detected by the second light receiving unit.

Description

Sensor below display screen and method for measuring intensity of external light by using sensor

Technical Field

The invention relates to a sensor below a display screen and a method for measuring the intensity of external light by using the sensor.

Background

The sensor below the display screen is not only used for portable electronic devices such as mobile phones or tablet computers, but also used for image electronic devices such as TVs or monitors. Recently, designs in which the display screen occupies almost the entire front surface of the electronic device are gradually increasing. Although the size of the display screen is gradually increased with the demand for a large screen, it is still necessary to secure at least a partial area of the front surface in order to arrange the camera, particularly in order to arrange the illuminance sensor. Although a proximity sensor using ultrasonic waves or the like can be applied to a structure in which the front surface is covered with a display screen, it is difficult to incorporate an illuminance sensing function. On the other hand, although the illuminance sensor may be located in an area other than the front surface, ambient light may not be detected due to a case protecting the electronic device. Therefore, although the optimal position where the illuminance sensor can be provided is the front surface of the electronic device, it is difficult to ensure a position where the illuminance sensor that is commonly used is arranged in a design where the display screen occupies the entire front surface.

When the illuminance sensor or the color sensor is disposed at the lower portion of the display screen, light generated in the display screen acts as interference that hinders accurate measurement. In the case of an illuminance sensor, the light generated by the display screen is added on the basis of the external light incident inside the sensor, thereby distorting the intensity of the measured external light.

Disclosure of Invention

Problems to be solved by the invention

The present invention aims to provide a means for enabling an optical sensor such as an illuminance sensor or a color sensor to be applied to the lower portion of a display screen.

Means for solving the problems

According to an aspect of the present invention, there is provided a sensor under a display screen, the sensor under the display screen being disposed at a lower portion of the display screen and including a pixel generating light, a display screen retardation layer disposed at an upper portion of the pixel, and a display screen polarizing layer. The sensor below the display screen may be, including: a light selection layer forming a first light path that passes through the non-polarized light incident from the display screen and all of the circularly polarized light and a second light path that passes through the non-polarized light and a portion of the circularly polarized light; a first light receiving unit that detects the unpolarized light from the display panel, the circularly polarized light from the display panel, and the circularly polarized light generated by external light incident on the display panel, which have passed through the first light path; and a second light receiving unit that detects the unpolarized light from the display panel, the circularly polarized light from the display panel, and the circularly polarized light formed by the external light incident on the display panel, which have passed through the second light path, wherein the intensity of the external light is calculated by an external light calculation formula that takes as input a first detection value detected by the first light receiving unit and a second detection value detected by the second light receiving unit.

As an embodiment, the ambient light calculation formula may be derived based on the following function: a function f_t derived based on a relationship between the first detection value and the intensity of the external light; a function f_a derived based on a relationship between the second detection value and the first detection value; a function f_du derived based on a relation between the detection value for the unpolarized light originating from the display screen detected by the first light receiving section and the detection value for the unpolarized light originating from the display screen detected by the second light receiving section; the function f_uc is derived based on a relation between the detection value for the non-polarized light originating from the display screen detected by the first light receiving unit and the detection value for the circularly polarized light originating from the display screen detected by the first light receiving unit.

As an embodiment, the function f_t may be derived based on the first detection value output in a state where the display screen is turned off, and the function f_a may be derived based on the first detection value and the second detection value output in a state where the display screen is turned off.

As an embodiment, the function f_du may be derived based on the first detection value and the second detection value output in a state where the display screen is not present.

As an embodiment, the function f_uc may be derived based on the first detection value and the second detection value output in a state where the display screen is turned on.

As an embodiment, the light selection layer may include: a sensor delay layer; a first sensor polarizing layer forming the first optical path at a lower portion of the sensor retardation layer; and a second sensor polarizing layer forming the second optical path at a lower portion of the sensor retardation layer.

As an embodiment, the light selection layer may include: a first sensor delay layer having a first slow axis; a second sensor delay layer having a second slow axis orthogonal to the first slow axis; and a sensor polarizing layer forming the first optical path at a lower portion of the first sensor retardation layer and forming the second optical path at a lower portion of the second sensor retardation layer.

As an embodiment, the light selection layer may include: a sensor delay layer; a first light-transmitting layer arranged alternately with the sensor delay layer; a sensor polarizing layer forming the second optical path at a lower portion of the sensor retardation layer; the second light-transmitting layer is arranged below the first light-transmitting layer.

As an embodiment, the sensor below the display screen may further include a color filter layer disposed below the light selection layer and configured of a plurality of individual color filters through which the light passing through the first light path and the second light path passes in different wavelength ranges.

As an embodiment, the plurality of individual color filters may include: a red filter that passes light belonging to a red wavelength region; a green filter that passes light belonging to a green wavelength region; a blue filter for transmitting light belonging to a blue wavelength region.

According to another aspect of the present invention, there is provided a method of measuring an intensity of external light using a sensor under a display screen, the sensor under the display screen being disposed at a lower portion of the display screen and including a pixel generating light, a display screen retardation layer disposed at an upper portion of the pixel, and a display screen polarizing layer. The method for measuring the intensity of the external light by using the sensor below the display screen may be that the method comprises the following steps: receiving the unpolarized light and all circularly polarized light incident from the display screen through the first optical path and outputting the received polarized light as a first detection value; receiving the unpolarized light incident from the display screen and a part of the circularly polarized light passing through a second optical path, and outputting the received light as a second detection value; substituting the first detection value and the second detection value into an ambient light calculation formula to calculate the intensity of the ambient light.

As an embodiment, the ambient light calculation formula may be derived based on the following function: a function f_t derived based on a relationship between the first detection value and the intensity of the external light; a function f_a derived based on a relationship between the second detection value and the first detection value; a function f_du derived based on a relation between the detection value for the non-polarized light originating from the display screen detected by the first light receiving portion and the detection value for the non-polarized light originating from the display screen detected by the second light receiving portion; the function f_uc is derived based on a relation between the detection value for the non-polarized light originating from the display screen detected by the first light receiving unit and the detection value for the circularly polarized light originating from the display screen detected by the first light receiving unit.

ADVANTAGEOUS EFFECTS OF INVENTION

The sensor under the display screen of the embodiment of the invention can eliminate the influence caused by the light incident through the unintended path.

Drawings

The present invention will be described below with reference to the embodiments shown in the drawings. For ease of understanding, the same reference numerals are given to the same constituent elements throughout the drawings. The structures shown in the drawings are only schematically illustrated embodiments for the purpose of illustrating the invention and do not limit the scope of the invention. In particular, in the drawings, some of the constituent elements are shown in somewhat exaggerated form for the purpose of facilitating the understanding of the present invention. Since the drawings are means for understanding the present invention, it is to be understood that the widths, thicknesses, etc. of the constituent elements shown in the drawings may be different in actual implementation.

Fig. 1 is a diagram for schematically illustrating the operation principle of a sensor under a display screen.

Fig. 2 is a diagram for schematically illustrating an embodiment of a color sensor under a display screen.

Fig. 3 is a diagram for schematically illustrating another embodiment of a color sensor under a display screen.

Fig. 4 is a diagram for schematically illustrating still another embodiment of a color sensor under a display screen.

Fig. 5 is a diagram schematically illustrating various light paths incident on the light receiving section in the color sensor below the display panel.

Fig. 6 is a flow chart schematically illustrating a method of canceling interference components across multiple optical paths.

Fig. 7 (a), 7 (b) and 7 (c) are diagrams for schematically explaining a process of simplifying the disturbance components passing through the plurality of optical paths, respectively.

Wherein, the reference numerals are as follows:

10. a display screen; 11. a display screen polarizing layer; 12. a display screen delay layer; 13. a pixel layer; 14. a glass cover; 20. ambient light; 21. linearly polarizing the display screen; 22. circularly polarized light of the display screen; 22', circularly polarized light; 22a, sensor internal linear polarization; 22a', linear polarization; 22b, first sensor internal linear polarization; 22c, second sensor internal linear polarization; 23. a first sensor linear polarization; 23', a first linear polarization; 24. a second sensor linear polarization; 24', a second linear polarization; 30. non-polarized light; 30', non-polarized light; 30", linearly polarized light; 31. a third sensor linear polarization; 31', third sensor linear polarization; 32. a fourth sensor linear polarization; 32', fourth sensor linear polarization; 100. a sensor under the display screen; 101. a color sensor under the display screen; 102. a color sensor under the display screen; 103. a color sensor under the display screen; 200. a light selection layer; 201. a light selection layer; 202. a light selection layer; 210. a first sensor polarizing layer; 215. a second sensor polarizing layer; 217. a first light-transmitting layer; 220. a first sensor delay layer; 225. a second sensor delay layer; 227. a second light-transmitting layer; 300. a light sensor; 310. a light receiving section; 311. a first light receiving section; 312. a second light receiving section; 320. a color filter layer.

Detailed Description

While the invention is susceptible to various modifications and alternative embodiments, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the intention is not to limit the invention to the particular embodiments, but to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In particular, the functions, features and some embodiments described below with reference to the drawings can be implemented alone or in combination with other embodiments. It should be noted, therefore, that the scope of the present invention is not limited by the manner shown in the drawings.

On the other hand, the expressions of "substantially", "almost", "about", and the like used in the present specification are expressions in which a margin (margin) or an error that may occur is considered to be applied in the actual implementation. For example, "substantially 90 degrees" should be interpreted as an angle including the same effect as that at 90 degrees. As another example, "substantially free" should be interpreted to include an extent that is present in a minimum but can be ignored.

On the other hand, unless otherwise specified, "side" or "horizontal" is used to describe the left-right direction of the drawing, and "vertical" is used to describe the up-down direction of the drawing. The angle, the incident angle, and the like are based on a virtual straight line perpendicular to a horizontal plane shown in the drawings unless otherwise specified.

The same reference numbers will be used throughout the drawings to refer to the same or like elements.

In the following, in the whole drawing, hatching displayed on the retardation layer indicates the direction of the slow axis, and hatching displayed on the polarizing layer schematically indicates the direction of the polarizing axis with respect to the slow axis extending in the horizontal direction. On the other hand, the slow axis of the display retarder and the slow axis of the sensor retarder are shown to both extend in a horizontal direction or the slow axis of the display retarder and the slow axis of the sensor retarder extend in a vertical direction. This is simply shown for ease of understanding only, with the understanding that it is not necessary to align the slow axis of the sensor retarder with the slow axis of the display retarder.

The sensor 100 below the display screen is arranged at the lower part of the display screen 10. The sensor 100 under the display screen is, for example, an illuminance sensor that measures the intensity of external light, or a color sensor that measures the intensity of light in at least two or more different wavelength regions in order to measure the intensity of external light. The sensor 100 below the display typically includes a sensor retarder layer and a sensor polarizer layer. The sensor retardation layer and the sensor polarizing layer reduce the effects caused by light generated by the display screen. Here, the illuminance sensor and the color sensor are the same in all but the color filter, and therefore, the color sensor will be mainly described below.

The display screen 10 includes: a pixel layer 13 formed with a plurality of pixels P that generate light; a display screen polarizing layer 11 laminated on the upper portion of the pixel layer 13; and a display delay layer 12. A protective layer, which is formed of an opaque material such as metal or synthetic resin and serves to protect the display polarizing layer 11, the display retarder layer 12, and the pixel layer 13, may be disposed on the lower surface of the display 10. As an example, the sensor 100 under the display screen constituted by the light selection layer 200 and the light sensor 300 may be disposed in a region where a part of the protective layer is removed (hereinafter, referred to as a completed structure). As another example, the light selection layer 200 of the sensor 100 below the display screen may be manufactured in a film-forming form to be laminated to the lower surface of the display screen 10. The light sensor 300 may be attached to the lower surface of the light selection layer 200, thereby realizing a color sensor under the display screen (hereinafter, referred to as an assembly type structure). In the following, description will be made centering on the completed structure in order to avoid repetitive description.

The display polarizing layer 11 and the display retardation layer 12 enhance the visibility of the display 10. Ambient light 20 incident through the upper surface of the display screen 10 is unpolarized. If the external light 20 is incident on the upper surface of the display screen polarizing layer 11, only the display screen linear polarization 21 substantially coincident with the polarization axis of the display screen polarizing layer 11 passes through the display screen polarizing layer 11. If the display linear polarization 21 passes through the display retardation layer 12, it becomes a display circular polarization (or elliptical polarization) 22 rotated in a clockwise direction or a counterclockwise direction. If the display circularly polarized light 22 is reflected at the pixel layer 13 and is incident again on the display retardation layer 12, it becomes reflected linearly polarized light. Here, if the polarization axis of the display screen retardation layer 12 is inclined at about 45 degrees with respect to the slow axis, the polarization axis of the display screen linear polarization 21 and the polarization axis of the reflected linear polarization are orthogonal to each other. Thus, the reflected linear polarization, that is, the external light reflected by the pixel layer 13 is blocked by the display polarizing layer 11 and cannot be emitted to the outside of the display. Thereby, the visibility of the display screen 10 can be improved.

The non-polarized light 30 generated by the pixel P travels not only toward the upper surface of the display screen 10 but also toward the lower surface of the display screen 10. A part of the non-polarized light 30 traveling toward the upper surface of the display screen 10 is reflected inside the display screen 10 and travels toward the lower surface of the display screen 10 again. Unlike the display circularly polarized light 22, the unpolarized light 30 passes through the display retardation layer 12 directly, passes through the display polarizing layer 11, becomes linearly polarized light, and is emitted to the outside.

The sensor 100 under the display screen includes: a light selection layer 200 forming two light paths; and a photosensor 300 detecting light passing through each optical path. The light incident on the sensor 100 below the display is the display circularly polarized light 22 formed by ambient light and the unpolarized light 30 generated inside the display. The first and second optical paths within the light selection layer 200 function differently for the display screen circular polarized light 22 and the non-polarized light 30. The first light path passes the display screen circularly polarized light 22 and all unpolarized light 30. In contrast, the second light path passes the unpolarized light 30 but substantially blocks the display screen circularly polarized light 22. The display screen circularly polarized light 22 passing through the first optical path becomes the first sensor linearly polarized light 23, the display screen circularly polarized light 22 passing through the second optical path becomes the second sensor linearly polarized light 24, and the non-polarized light 30 passing through the first optical path and the second optical path becomes the third sensor linearly polarized light 31 and the fourth sensor linearly polarized light 32. Here, the second sensor linear polarization 24 may be different according to polarization efficiency (PE, polarization Efficiency) of the light selection layer 200. For example, if the polarization efficiency of the light selection layer 200 is 100%, the display screen circularly polarized light 22 is completely blocked by the light selection layer 200, so that the second sensor linearly polarized light 24 is not generated. If the polarization efficiency of the light selection layer 200 is less than 100%, a portion of the display screen circularly polarized light 22 passes through the light selection layer 200 to become the second sensor linearly polarized light 24.

The light sensor 300 includes: the first light receiving unit 311 corresponds to the first optical path; and a second light receiving portion 312 corresponding to the second optical path. For example, the first light receiving unit 311 generates a first pixel current substantially proportional to the light amounts of the first sensor linear polarization 23 and the third sensor linear polarization 31, and the second light receiving unit 312 generates a second pixel current substantially proportional to the light amounts of the second sensor linear polarization 24 and the fourth sensor linear polarization 32. The first light receiving portion 311 or the second light receiving portion 312 may be constituted by one photodiode or a plurality of photodiodes (hereinafter referred to as a PD array), for example. As an example, one or two photodiodes may correspond to one pixel P. As another example, the PD array may correspond to one pixel P. As yet another embodiment, one or two photodiodes may correspond to a plurality of pixels P. As yet another embodiment, the PD array may correspond to a plurality of pixels P.

As described above, the third sensor linear polarization 31 and the fourth sensor linear polarization 32 formed of the unpolarized light 30 can be detected by the first light receiving unit 311 and the second light receiving unit 312, respectively. On the other hand, although described in detail below, the intensities of the third sensor linear polarization 31 and the fourth sensor linear polarization 32 may be substantially the same, or may be different. However, since the third sensor linear polarization 31 and the fourth sensor linear polarization 32 are formed of the non-polarized light 30 generated by one or a plurality of pixels, a linear proportional relationship or a non-linear proportional relationship is established between the intensities of the two. The nonlinear proportional relationship may be caused by various reasons such as structural characteristics of the display panel 10, differences in pixel areas corresponding to the light receiving portions, and wavelength ranges of the unpolarized light 30. The proportional relationship between the third sensor linear polarization 31 and the fourth sensor linear polarization 32 can be measured in an environment that is not affected by external light. According to the proportional relationship, the influence on the third sensor linear polarization 31 by the intensity measured by the first light receiving unit 311 can be calculated based on the intensity of the fourth sensor linear polarization 32 measured by the second light receiving unit 312.

The color sensor 101 under the display screen is a device that measures the intensity of light of at least two or more different wavelength domains in order to measure the intensity of external light. When the color sensor is disposed at the lower portion of the display screen, not only the external light that has passed through the display screen is incident on the color sensor, but also the light generated inside the display screen is incident on the color sensor. Therefore, in order to accurately measure the intensities of light of at least two or more wavelength domains separately and simultaneously, it is necessary to measure the intensities of light generated inside the display screen. If only the intensity of the light generated inside the display screen can be measured, this can be used to correct the measured intensity of the light of the different wavelength domains.

The color sensor 101 under the display screen comprises a light selection layer 200 and a light sensor 300. The light selection layer 200 includes a first sensor retardation layer 220, a first sensor polarizing layer 210, and a second sensor polarizing layer 215. The first sensor retardation layer 220 is disposed on the first sensor polarizing layer 210 and the second sensor polarizing layer 215, and the optical sensor 300 is disposed on the first sensor polarizing layer 210 and the second sensor polarizing layer 215. A color filter layer 320 is disposed between the first sensor polarizing layer 210 and the second sensor polarizing layer 215 and the photosensor 300, and the color filter layer 320 is used to define a wavelength range of light incident on the light receiving section 310. The light receiving unit 310 of the photosensor 300 is composed of a first light receiving unit 311 and a second light receiving unit 312. The first light receiving portion 311 is disposed below the first sensor polarizing layer 210, and the second light receiving portion 312 is disposed below the second sensor polarizing layer 215. As an example, the light selection layer 200 may be manufactured in such a manner that the first sensor retardation layer 220 is laminated (laminated) on the upper surfaces of the first sensor polarizing layer 210 and the second sensor polarizing layer 215. The light selection layer 200 may be attached to the lower surface of the display screen 10. The light sensor 300 may be attached to the lower surface of the light selection layer 200. As another embodiment, the light sensor 300 can be implemented by a thin film transistor. Thus, the color sensor 101 under the display screen can be manufactured by laminating the first sensor retardation layer 220, the first sensor polarizing layer 210, the second sensor polarizing layer 215, and the light sensor 300 in the form of a film.

The polarization axis of the first sensor polarization layer 210 and the polarization axis of the second sensor polarization layer 215 are inclined at different angles with respect to the slow axis of the first sensor retardation layer 220. The polarization axis of the first sensor polarization layer 210 may be tilted at a first angle, e.g., at +45 degrees, with respect to the slow axis of the first sensor retardation layer 220, and the polarization axis of the second sensor polarization layer 215 may be tilted at a second angle, e.g., at-45 degrees, with respect to the slow axis of the first sensor retardation layer 220.

The first light receiving unit 311 of the light sensor 300 detects the first sensor linear polarization 23 and the third sensor linear polarization 31 emitted from the first sensor polarizing layer 210, and the second light receiving unit 312 detects the second sensor linear polarization 24 and the fourth sensor linear polarization 32 emitted from the second sensor polarizing layer 215. Since the first sensor linear polarization 23, the second sensor linear polarization 24, the third sensor linear polarization 31, and the fourth sensor linear polarization 32 pass through the color filter layer 320, the light receiving section 310 can generate pixel currents having magnitudes corresponding to the light amounts of light of different wavelength domains. For example, the light receiving portion 310 may be a photodiode, but is not limited thereto. Here, the first light receiving unit 311 and the second light receiving unit 312 can commonly detect any one of the lights belonging to different wavelength ranges such as red, green, blue, and white, for example.

The color filter layer 320 is located between the light sensor 300 and the light selection layer 200. The color filter layer 320 may be composed of, for example, red (R), green (G), blue (B), and white (W) color filters. Each color filter may be located at a vertical upper portion substantially perpendicular to the first light receiving portion 311 or the second light receiving portion 312. The color filter passes light belonging to a specific wavelength region and substantially blocks light not belonging to the specific wavelength region.

Hereinafter, the operation of the color sensor 101 under the display screen of the light selection layer 200 having the above-described structure will be described.

The display circularly polarized light 22 and the unpolarized light (not shown, 30 of fig. 1) are incident on the upper surface of the light selection layer 200, i.e., the upper surface of the first sensor retardation layer 220. The display circularly polarized light 22 is light after the external light 20 passes through the display polarizing layer 11 and the display retarder 12, and the unpolarized light 30 is light traveling downward from the pixel P toward the light selection layer 200.

The display screen polarizing layer 11 may have a polarizing axis that is tilted at a second angle, e.g., at-45 degrees, with respect to the slow axis of the display screen retardation layer 12. Accordingly, the display screen linear polarization 21 passing through the display screen polarization layer 11 can be incident at the second angle with respect to the slow axis of the display screen retardation layer 12. If the first polarized light portion of the display screen linear polarized light 21 projected along the fast axis and the second polarized light portion of the display screen linear polarized light 21 projected along the slow axis pass through the display screen retardation layer 12, a phase difference of λ/4 is generated between each other. Thus, the display linear polarization 21 passing through the display retardation layer 12 can be the display circular polarization 22 rotated in the counterclockwise direction.

The display screen circularly polarized light 22 having a phase difference of λ/4 between the fast axis and the slow axis is formed into the sensor internal linearly polarized light 22a by the first sensor retardation layer 220. The polarization axis of the sensor internal linear polarization 22a and the polarization axis of the display screen linear polarization 21 are orthogonal to each other. On the other hand, the unpolarized light 30 passes directly through the first sensor retardation layer 220.

Since the polarization axis of the first sensor polarization layer 210 is substantially parallel to the polarization axis of the sensor internal linear polarization 22a, the sensor internal linear polarization 22a emitted from the first sensor retardation layer 220 can pass through the first sensor polarization layer 210. In contrast, since the polarization axis of the second sensor polarization layer 215 is substantially perpendicular to the polarization axis of the sensor internal linear polarization 22a, the sensor internal linear polarization 22a is substantially blocked by the second sensor polarization layer 215. On the other hand, the unpolarized light 30 emitted from the first sensor retardation layer 220 passes through the first sensor polarization layer 210 and the second sensor polarization layer 215, respectively, to become the third sensor linear polarization 31 and the fourth sensor linear polarization 32. The first sensor linear polarization 23, the second sensor linear polarization 24, the third sensor linear polarization 31, and the fourth sensor linear polarization 32 pass through the same type of color filter (hereinafter referred to as the same type of color filter) and then enter the photosensor 300. That is, the first light receiving unit 311 can detect the first sensor linear polarization 23 and the third sensor linear polarization 31 through the first light path formed by the first sensor retardation layer 220 and the first sensor polarizing layer 210, and the second light receiving unit 312 can detect the second sensor linear polarization 24 and the fourth sensor linear polarization 32 through the second light path formed by the first sensor retardation layer 220 and the second sensor polarizing layer 215.

The color sensor 102 below the display screen comprises a light selection layer 201 and a light sensor 300. The light selection layer 201 includes a first sensor retardation layer 220, a second sensor retardation layer 225, and a first sensor polarizing layer 210. The first sensor retardation layer 220 and the second sensor retardation layer 225 are disposed on the upper portion of the first sensor polarization layer 210, and the photosensor 300 is disposed on the lower portion of the first sensor polarization layer 210. A color filter layer 320 is disposed between the first sensor polarizing layer 210 and the photosensor 300, and the color filter layer 320 is used to define a wavelength range of light incident on the light receiving unit 310. The first light receiving portion 311 of the photosensor 300 is disposed at a position where light emitted from the first sensor retardation layer 220 passes through the first sensor polarizing layer 210, and the second light receiving portion 312 is disposed at a position where light emitted from the second sensor retardation layer 225 passes through the first sensor polarizing layer 210. As an example, the light selection layer 201 may be manufactured by laminating the first sensor retardation layer 220 and the second sensor retardation layer 225 on the upper surface of the first sensor polarization layer 210. The light selection layer 201 may be attached to the lower surface of the display screen 10. The light sensor 300 may be attached to the lower surface of the light selection layer 201. As another embodiment, the light sensor 300 can be implemented by a thin film transistor. Thus, the color sensor 102 under the display screen can be manufactured by laminating the first sensor retardation layer 220, the second sensor retardation layer 225, the first sensor polarizing layer 210, and the light sensor 300 in the form of a film.

The slow axis of the first sensor delay layer 220 is substantially orthogonal to the slow axis of the second sensor delay layer 225. The polarization axis of the first sensor polarization layer 210 may be tilted at a first angle, e.g., at +45 degrees, with respect to the slow axis of the first sensor retardation layer 220, or at a second angle, e.g., at-45 degrees, with respect to the slow axis of the second sensor retardation layer 225.

The first light receiving portion 311 of the light sensor 300 is located at a vertically lower portion of the first sensor retardation layer 220, and detects the first sensor linear polarized light 23 and the third sensor linear polarized light 31 emitted from the display screen circular polarized light 22 passing through the first sensor retardation layer 220 and the first sensor polarized light layer 210. The second light receiving portion 312 of the light sensor 300 is located at a vertically lower portion of the second sensor retardation layer 225, and detects the second sensor linear polarized light 24 and the fourth sensor linear polarized light 32. The first light receiving unit 311 and the second light receiving unit 312 can generate a pixel current having a magnitude corresponding to the light amount of the detected light. The light receiving unit 310 can generate pixel currents having magnitudes corresponding to the light amounts of light in different wavelength regions. For example, the light receiving portion 310 may be a photodiode, but is not limited thereto.

The color filter layer 320 is located between the light sensor 300 and the light selection layer 200. In detail, the color filter layer 320 may be composed of, for example, red (R), green (G), blue (B), and white (W) color filters. Each color filter may be located at a vertical upper portion substantially perpendicular to the first light receiving portion 311 or the second light receiving portion 312. The color filter passes light belonging to a specific wavelength region and blocks light not belonging to the specific wavelength region.

Hereinafter, the operation of the color sensor 102 under the display screen of the light selection layer 201 having the above-described structure will be described. Since the display screen circularly polarized light 22 and the non-polarized light 30 are described in the same manner as in fig. 2, the description thereof will be omitted.

The display circularly polarized light 22 and non-polarized light (not shown; 30 of fig. 1) are incident on the upper surfaces of the light selection layer 201, i.e., the upper surfaces of the first sensor retardation layer 220 and the second sensor retardation layer 225. The display screen circularly polarized light 22 having a phase difference of λ/4 between the fast axis and the slow axis becomes the first sensor internal linearly polarized light 22b by the first sensor retardation layer 220, and becomes the second sensor internal linearly polarized light 22c by the second sensor retardation layer 225. Since the slow axis of the first sensor retardation layer 220 is orthogonal to the slow axis of the second sensor retardation layer 225, the polarization axis of the first sensor internal linear polarization 22b is also orthogonal to the polarization axis of the second sensor internal linear polarization 22c. In detail, the display screen circular polarized light 22 having a phase difference of λ/4 between the first polarized light portion and the second polarized light portion increases the phase difference of λ/4 by the first sensor retardation layer 220, thereby becoming the first sensor internal linear polarized light 22b having a polarized light axis perpendicular to the polarized light axis of the display screen linear polarized light 21. In contrast, the second sensor retardation layer 225 causes the phase difference to disappear, and the display screen circularly polarized light 22 becomes the second sensor internal linearly polarized light 22c having a polarization axis substantially parallel to the polarization axis of the display screen linearly polarized light 21. On the other hand, the unpolarized light 30 passes directly through the first and second sensor retardation layers 220 and 225.

Although the first sensor internal linear polarization 22b emitted from the first sensor retardation layer 220 passes through the first sensor polarization layer 210, most of the second sensor internal linear polarization 22c emitted from the second sensor retardation layer 225 cannot pass through the first sensor polarization layer 210, and only a part passes through. The first sensor polarization layer 210 has a polarization axis that is tilted at a first angle, e.g., +45 degrees, with respect to the slow axis of the first sensor retardation layer 220 or at a second angle, e.g., -45 degrees, with respect to the slow axis of the second sensor retardation layer 225. Accordingly, the polarization axis of the first sensor internal linear polarization 22b is substantially parallel to the polarization axis of the first sensor polarization layer 210, whereby the first sensor internal linear polarization 22b can pass through the first sensor polarization layer 210 with little loss. In contrast, the polarization axis of the second sensor internal linear polarization 22c is substantially perpendicular to the polarization axis of the first sensor polarization layer 210, and therefore, most of the second sensor internal linear polarization 22c is blocked by the first sensor polarization layer 210, and only a part passes through to become the second sensor linear polarization 24. On the other hand, the unpolarized light 30 having passed through the first and second sensor retardation layers 220 and 225 passes through the first sensor polarizing layer 210 to become the third and fourth sensor linear polarized light 31 and 32. The first sensor linear polarization 23, the second sensor linear polarization 24, the third sensor linear polarization 31, and the fourth sensor linear polarization 32 are incident to the photosensor 300 after passing through the same color filter. That is, the first light receiving unit 311 can detect the first sensor linear polarization 23 and the third sensor linear polarization 31 through the first optical path formed by the first sensor retardation layer 220 and the first sensor polarization layer 210. On the other hand, the second light receiving unit 312 can detect the second sensor linear polarization 24 and the fourth sensor linear polarization 32 through the second optical path constituted by the second sensor retardation layer 225 and the first sensor polarization layer 210.

Fig. 4 is a diagram for schematically illustrating still another embodiment of a color sensor under a display screen. The description of the embodiments is omitted from the repeated descriptions of fig. 1 to 3, and mainly focuses on the differences.

The color sensor 103 below the display screen is arranged at the lower part of the display screen 10. The color sensor 103 below the display screen includes: a light selection layer 202 having two light paths; a color filter layer 320 disposed under the light selection layer 202; and a photosensor 300 disposed under the color filter layer 320 and detecting light passing through each light path. The light incident on the color sensor 103 below the display is a display circularly polarized light 22 formed by ambient light 20 and a non-polarized light 30 generated inside the display.

The first and second light paths within the light selection layer 202 act differently on the display screen circularly polarized light 22 and the non-polarized light 30. The first light path passes the display screen circularly polarized light 22 and unpolarized light 30 directly through. The display circularly polarized light 22 and the non-polarized light 30 having passed through the first optical path reach the first light receiving portion 311. In contrast, the second light path passes through the unpolarized light 30 and blocks a substantial portion of the display screen circularly polarized light 22. A part of the display screen circularly polarized light 22 having passed through the second optical path becomes the second sensor linearly polarized light 24, and the non-polarized light 30 having passed through the second optical path becomes the fourth sensor linearly polarized light 32, and reaches the second light receiving portion 312.

The light selection layer 202 includes a second sensor polarizing layer 215 having a second polarizing axis, a first light transmissive layer 217, a first sensor retarder layer 220 having a first slow axis, and a second light transmissive layer 227. Here, the first slow axis may be inclined at a second angle with respect to a second polarization axis of the second sensor polarization layer 215. The second sensor polarizing layer 215 and the first light-transmitting layer 217 are arranged in an alternating manner, and the first sensor retardation layer 220 and the second light-transmitting layer 227 are arranged in an alternating manner at an upper portion of the second sensor polarizing layer 215 and the first light-transmitting layer 217. Here, the second light-transmitting layer 227 is disposed on the upper portion of the first light-transmitting layer 217, and the first sensor retardation layer 220 is disposed on the upper portion of the second sensor polarizing layer 215. The first light-transmitting layer 217 and the second light-transmitting layer 227 may be formed of a substance having the same or similar light transmittance, and enable incident light to pass through substantially without loss. The display circularly polarized light 22 and the non-polarized light 30 can be detected by the first light receiving portion 311, and the second sensor linearly polarized light 24 and the fourth sensor linearly polarized light 32 can be detected by the second light receiving portion 312.

Fig. 5 is a diagram schematically illustrating various light paths incident on the light receiving section in the color sensor below the display panel. Since the color sensors 101, 102, 103 under the display screen shown in fig. 2 to 4 are different only in terms of the structure of the light selection layer 200 and operate in the same manner, the color sensor 101 under the display screen shown in fig. 2 will be described below as an example.

In the color sensor 101 below the display screen, light is incident on the light receiving section through various paths. In fig. 2 to 4, regarding the non-polarized light 30 irradiated from the pixel P toward the light receiving portion, only the third sensor linear polarized light 31 and the fourth sensor linear polarized light 32 passing through the light selection layer 200 are considered (case 1). However, a plurality of interfaces between layers having different refractive indices and/or structures for reflecting light (hereinafter, collectively referred to as reflecting elements) exist inside the display panel. Although most of the light irradiated by the pixels P travels toward the outside of the display panel 10, a part is reflected inside the display panel 10 and travels toward the light receiving portion 310 (case 2 to case 5).

The color sensor 101 under the display screen measures the intensity of the external light (case 6). Therefore, of the light incident to the color sensor below the display screen, the light corresponding to cases 1 to 5 is an interference component, which may prevent accurate measurement of external light. In cases 1 to 5, when passing through the first optical path and the second optical path, it is possible to distinguish based on the difference in the intensity of light passing through the two paths. In cases 1 to 3, the intensities of the light passing through the first and second light paths are substantially the same. In contrast, in case 4 and case 5, the intensities of the light passing through the first and second light paths are different.

In cases 1 to 3, the light reaching the light receiving portion 310 is polarized light formed of unpolarized light. The light corresponding to the case 2 and the case 3 has substantially the same properties as the light corresponding to the case 1 except for the point of reflection inside the display screen 10. In other words, the intensities of the two lights passing through the first light path and the second light path are substantially the same, and their polarization axes are substantially orthogonal.

In case 1, light traveling downward from the pixel P is unpolarized light 30. The unpolarized light 30 passes directly through the first sensor retardation layer 220 and becomes the third sensor linear polarization 31 and the fourth sensor linear polarization 32 through the first sensor polarizing layer 210 and the second sensor polarizing layer 215.

In case 2, a part of the non-polarized light 30 traveling upward from the pixel P is reflected by the reflective element located between the lower surface of the display screen retardation layer 12 and the pixel layer 13 and travels downward. The reflected unpolarized light 30' passes directly through the first sensor retardation layer 220 and passes through the first sensor polarizing layer 210 and the second sensor polarizing layer 215 to become the third sensor linear polarization 31' and the fourth sensor linear polarization 32'.

In case 3, a part of the non-polarized light 30 traveling from the pixel P toward the upper side and directly passing through the display retardation layer 12 is reflected by the lower surface of the display polarizing layer 11 or a reflection element located between the lower surface of the display polarizing layer 11 and the display retardation layer 12 to travel toward the lower side. The reflected unpolarized light 30' passes directly through the display retarder 12 and the first sensor retarder 220, and passes through the first sensor polarizer 210 and the second sensor polarizer 215 to become the third sensor linear polarization 31' and the fourth sensor linear polarization 32'.

In case 4 and case 5, the light reaching the light receiving portion 310 is polarized light formed by circularly polarized light. The light corresponding to case 4 and case 5 has substantially the same properties as the light corresponding to case 6 except that the place of reflection is different in the inside of the display screen 10. In other words, the intensities of the two lights passing through the first light path and the second light path are different. Since light corresponding to case 6 is described in detail with reference to fig. 1 to 4, a detailed description thereof is omitted.

In case 4, a part of the non-polarized light 30 going upward from the pixel P and passing directly through the display retardation layer 12 is reflected inside the display polarizing layer 11 or on the upper surface of the display polarizing layer 11 as linear polarized light 30", and the linear polarized light 30" goes downward. The linear polarization 30 "passes through the display retarder 12 as circular polarization 22', and the circular polarization 22' passes through the first sensor retarder 220 as linear polarization 22a '. The linear polarization 22a ' passes through the first sensor polarization layer 210 and the second sensor polarization layer 215 to become the first linear polarization 23' and the second linear polarization 24'.

In case 5, the unpolarized light 30 travels upward from the pixel P, passes through the display screen polarizing layer 11, and becomes linearly polarized light 30". A portion of the linear polarization light 30″ is reflected by the upper surface of the glass cover 14 or a reflection element located between the upper surface of the glass cover 14 and the display screen polarization layer 11 to travel downward. The linear polarization 30 "passes through the display retarder 12 as circular polarization 22', and the circular polarization 22' passes through the first sensor retarder 220 as linear polarization 22a '. The linear polarization 22a ' passes through the first sensor polarization layer 210 and the second sensor polarization layer 215 to become the first linear polarization 23' and the second linear polarization 24'.

Fig. 6 is a flowchart schematically showing a method of eliminating interference components passing through a plurality of optical paths, and fig. 7 is a diagram for schematically explaining a process of simplifying the interference components passing through the plurality of optical paths.

Referring to fig. 6 and 7, a transmission function f_t is derived (step S10). The color sensor 101 below the display screen is disposed at the lower portion of the display screen 10, and measures the intensity of external light passing through the display screen 10. As the intensity a of the external light decreases as it passes through the display panel 10 and the color sensor 101 under the display panel, the intensity bright_a detected by the first light receiving portion is different from the intensity a of the external light. Therefore, equation 1 holds between the intensity a of the external light and the intensity bright_a detected by the first light receiving portion.

Equation 1:

A＝f_t(Bright_A)

Equation 1 is derived based on the intensity bright_a detected by the first light receiving portion 311 of the color sensor 101 below the display screen in a state where the display screen 10 is turned off. Referring to fig. 7 (a), the intensity a of external light is measured by an illuminometer (not shown). The relation between the intensities bright_a of the light detected by the first light receiving portion is derived by adjusting the intensity a of the external light.

An external light function f_a between the intensity bright_a of the light detected by the first light receiving portion and the intensity dark_a of the light detected by the second light receiving portion is derived (step S11). Equation 2 holds between the intensity bright_a of light detected by the first light receiving portion and the intensity dark_a of light detected by the second light receiving portion.

Equation 2:

Dark_A＝f_a(Bright_A)

Equation 2 is derived based on the intensity bright_a detected by the first light receiving portion 311 and the intensity dark_a detected by the second light receiving portion 312 of the color sensor 101 below the display screen in the state where the display screen 10 is turned off. Referring to fig. 7 (a), an ambient light function f_a representing the relationship between bright_a and dark_a is derived by adjusting the intensity a of ambient light.

The first display function f_du and the second display function f_uc are derived (step S12). The first display function f_du is derived based on the interference components belonging to cases 1 to 3. Referring to fig. 7 (b), since lights corresponding to cases 1 to 3 have substantially the same characteristics, they can be combined into case 1. If unpolarized light, i.e., external light, is incident on the upper surface of the color sensor 101 below the display screen, the intensity bright_pu measured by the first light receiving unit 311 and the intensity dark_pu measured by the second light receiving unit 312 can be obtained.

Equation 3:

Dark_PU＝f_du(Bright_PU)

Equation 3 is derived by deriving based on bright_pu and dark_pu obtained by measuring only external light in a state where the display screen 10 is not present. Referring to fig. 7 (b), a first display function f_du representing a relationship between bright_pu and dark_pu is derived by adjusting the intensity a of external light.

On the other hand, the interference components corresponding to the cases 4 and 5 are detected by the first light receiving portion 311 and the second light receiving portion 312, and the detected intensities are bright_pc and dark_pc. The relationship of bright_pc to dark_pc may be represented by dark_pc=f_dc (Brignt _pc). On the other hand, as shown in fig. 5, the characteristics of the interference components corresponding to case 4 and case 5 are substantially the same as those of the light corresponding to case 6, and therefore, dark_pc=f_dc (Brignt _pc) can be expressed as follows using formula 2.

Equation 4:

Dark_PC＝f_a(Bright_PC)

Referring to fig. 7 (c), in a state where there is no external light, if the display screen 10 is turned on, the intensities of the light detected by the first light receiving portion 311 and the second light receiving portion 312 are interference components corresponding to cases 1 to 5. Therefore, in a state where no external light is present and only the display screen 10 is turned on, the intensity measured by the first light receiving portion 311 is the sum of bright_pu and bright_pc. Thus, a second display function f_uc representing the relationship between bright_pu and bright_pc can be derived.

Equation 5:

Bright_PU＝f_uc(Bright_PC)

It is to be understood that, regarding the above steps S10 to S12, the description is made in a time series manner for convenience of description, but the present invention is not limited thereto.

The variable is reduced to obtain an ambient light equation for calculating the intensity a of the ambient light (step S13). The intensities Bright and Dark generated by the first light receiving unit 311 and the second light receiving unit 312 detecting all the lights corresponding to the cases 1 to 6 can be expressed as follows.

Equation 6:

Bright＝Bright_A+Bright_PU+Bright_PC

Dark＝Dark_A+Dark_PU+Dark_PC

Here, bright and Dark may be represented by only the variables bright_a and bright_pc. With respect to Bright_PU, bright_PC is taken as the sole variable through equation 5. Regarding dark_a, only bright_a is used as a variable by formula 2, regarding dark_pu, bright_pc is used as a unique variable by formulas 3 and 5, and regarding dark_pc, only bright_pc is used as a variable by formula 4.

Equation 7:

Bright＝Bright A+f_uc(Bright_PC)+Bright_PC

Dark＝f_a(Bright_A)+f_du(Bright_PU)+f_a(Bright_PC)

＝f_a(Bright_A)+f_du(f_uc(Bright_PC))+f_a(Bright_PC)

Since equation 7 is two polynomials with two variables bright_a and bright_pc, if the variable bright_pc is eliminated in the two polynomials, it is expressed as one or more times of equations represented by variables bright_ A, bright and Dark. If it is sorted into bright_a and substituted into equation 1, an ambient light calculation equation can be derived that represents the intensity a of ambient light with measured values Bright and Dark.

Equation 8:

A＝F1(Bright，Dark)

The first light receiving unit 311 and the second light receiving unit 312 generate Bright and Dark (step S20). In a state where the display screen 10 is turned on, the first light receiving portion 311 and the second light receiving portion 312 receive external light and interference components (case 1 to case 5), and output Bright and Dark corresponding to the intensity of the received light. Bright and Dark are substituted into the ambient light calculation formula a=f1 (Bright, dark), and the intensity a of the ambient light is calculated therefrom (step S21).

The above description of the present invention is for illustration, and it will be understood by those skilled in the art that the present invention can be easily modified into other different embodiments without changing the technical spirit or essential features of the present invention. Accordingly, it should be understood that the above-described embodiments are illustrative only and not limiting in all respects.

The scope of the present invention should be indicated by the scope of the claims, not by the foregoing detailed description, and all changes and modifications that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. A sensor under a display screen, which is disposed at a lower portion of the display screen and includes a pixel generating light, a display screen retardation layer disposed at an upper portion of the pixel, and a display screen polarizing layer, the sensor under the display screen comprising:

A light selection layer forming a first light path that passes through the non-polarized light incident from the display screen and all of the circularly polarized light and a second light path that passes through the non-polarized light and a portion of the circularly polarized light;

A first light receiving unit that detects the unpolarized light from the display panel, the circularly polarized light from the display panel, and the circularly polarized light generated by external light incident on the display panel, which have passed through the first light path;

A second light receiving unit configured to detect the unpolarized light from the display panel, the circularly polarized light from the display panel, and the circularly polarized light generated by the external light incident on the display panel, which have passed through the second light path,

The intensity of the external light is calculated by an external light calculation formula, which takes as input a first detection value detected by the first light receiving part and a second detection value detected by the second light receiving part,

The ambient light calculation formula is derived based on the following function:

A function f_t derived based on a relationship between the first detection value and the intensity of the external light;

a function f_a derived based on a relationship between the second detection value and the first detection value;

A function f_du derived based on a relation between the detection value for the unpolarized light originating from the display screen detected by the first light receiving section and the detection value for the unpolarized light originating from the display screen detected by the second light receiving section;

A function f_uc derived based on a relation between a detection value for the non-polarized light originating from the display screen detected by the first light receiving portion and a detection value for the circularly polarized light originating from the display screen detected by the first light receiving portion,

The function f _ t is derived based on the first detection value output in a state of closing the display screen,

The function f_a is derived based on the first detection value and the second detection value output in a state where the display screen is turned off.

2. The sensor under a display screen according to claim 1, wherein,

The function f_du is derived based on the first detection value and the second detection value output in a state where the display screen is not present.

3. The sensor under a display screen according to claim 1, wherein,

The function f_uc is derived based on the first detection value and the second detection value output in a state where the display screen is turned on.

4. The sensor under a display screen according to claim 1, wherein,

The light selection layer includes:

a sensor delay layer;

a first sensor polarizing layer forming the first optical path at a lower portion of the sensor retardation layer;

and a second sensor polarizing layer forming the second optical path at a lower portion of the sensor retardation layer.

5. The sensor under a display screen according to claim 1, wherein,

The light selection layer includes:

a first sensor delay layer having a first slow axis;

a second sensor delay layer having a second slow axis orthogonal to the first slow axis;

And a sensor polarizing layer forming the first optical path at a lower portion of the first sensor retardation layer and forming the second optical path at a lower portion of the second sensor retardation layer.

6. The sensor under a display screen according to claim 1, wherein,

The light selection layer includes:

a sensor delay layer;

a first light-transmitting layer arranged alternately with the sensor delay layer;

a sensor polarizing layer forming the second optical path at a lower portion of the sensor retardation layer;

The second light-transmitting layer is arranged below the first light-transmitting layer.

7. The sensor under a display screen according to claim 1, wherein,

The sensor below the display screen further includes a color filter layer disposed below the light selection layer and configured of a plurality of individual color filters through which light having passed through the first light path and the second light path passes in different wavelength regions, respectively.

8. The sensor under a display screen according to claim 7, wherein,

The plurality of individual color filters includes:

a red filter that passes light belonging to a red wavelength region;

A green filter that passes light belonging to a green wavelength region;

a blue filter for transmitting light belonging to a blue wavelength region.

9. A method for measuring an intensity of external light using a sensor under a display screen, the sensor under the display screen being disposed at a lower portion of the display screen and including a pixel generating light, a display screen retardation layer disposed at an upper portion of the pixel, and a display screen polarizing layer, the method for measuring an intensity of external light using the sensor under the display screen comprising:

receiving the unpolarized light and all circularly polarized light incident from the display screen through the first optical path and outputting the received polarized light as a first detection value;

receiving the unpolarized light incident from the display screen and a part of the circularly polarized light passing through a second optical path, and outputting the received light as a second detection value;

A step of substituting the first detection value and the second detection value into an outside light calculation formula to calculate the intensity of the outside light,

a function f_du derived based on a relation between the detection value for the non-polarized light originating from the display screen detected by the first light receiving portion and the detection value for the non-polarized light originating from the display screen detected by the second light receiving portion;

10. The method of measuring the intensity of ambient light using an under-screen sensor of claim 9,

11. The method of measuring the intensity of ambient light using an under-screen sensor of claim 9,