WO2018107881A1

WO2018107881A1 - Ambient light detection system

Info

Publication number: WO2018107881A1
Application number: PCT/CN2017/105696
Authority: WO
Inventors: 王预; 於丰; 李吉贞
Original assignee: 华为技术有限公司
Priority date: 2016-12-12
Filing date: 2017-10-11
Publication date: 2018-06-21
Also published as: CN106644061A

Abstract

Disclosed is an electronic device having an ambient light detection system. The ambient light detection system comprises: an optical window (300), a micro/nano optical element (401) and an ambient light sensor (402), wherein the micro/nano optical element (401) is located between the optical window (300) and the ambient light sensor (402). The ambient light detection system is used for making light rays from the optical window (300) incident on the micro/nano optical element (401) and pass through the micro/nano optical element (401) so same are received by the ambient light sensor (402). The micro/nano optical element (401) has a micro/nano optical structure (403), the micro/nano optical structure (403) being used to change the direction of incident light rays. The use of the micro/nano optical element (401) to change the incident light path reduces loss of incident light due to absorption and reflection, and the loss of light rays when passing through the micro/nano optical element (401) is less, increasing the range of light received by the ambient light sensor (402).

Description

Ambient light detection system

The present application claims priority to Chinese Patent Application No. 201611141437.2, filed on Dec. 12, 2016, the entire disclosure of which is incorporated herein by reference.

Technical field

The present application relates to the field of optical technologies, and in particular, to an electronic device and an ambient light detecting system.

Background technique

For electronic devices such as mobile phones, notebook computers, and tablet computers, the ambient light sensor (ALS) system is one of the main photoelectric sensor systems, mainly used to receive ambient light, and to control the electronic device by detecting changes in ambient light. Screen brightness to maximize battery life and help the screen provide a softer picture for a better user experience. FIG. 1 is a schematic diagram of an ALS system in a prior art electronic device, the ambient light sensor being mounted under the glass cover. On the one hand, the range of ambient light received by the ambient light window size on the glass cover above it

The size determines that the larger the window size, the larger the receiving range of the ambient light sensor. However, in order to achieve aesthetic appearance and color consistency, the ambient light window size on the glass cover is usually as small as possible. On the other hand, the receiving range of the ambient light sensor is also determined by the distance d from the ambient light sensor to the window opening. The closer the distance, the larger the receiving range of the ambient light sensor. However, the actual product is far away from the window because of factors such as installation error, influence of peripheral devices, and ease of assembly. These two factors lead to the shortcomings of the ambient light sensor with a small receiving range.

The prior art uses a translucent leveling ink to achieve the purpose of expanding the receiving range. As shown in FIG. 2, fine particles such as zinc oxide or titanium oxide are added to the translucent uniform light ink to diffuse the incident light, and the receiving range of the ambient light sensor can be improved to some extent. However, the diffusing particles in the translucent homogenous ink also have a reflection and absorption effect on the incident light, reducing the transmittance of the incident light. Generally, as the content of the diffusion particles increases, the diffusion angle of the incident light increases, and the receiving range of the optical ambient light sensor increases, but the transmittance of the incident light also rapidly decreases, which leads to the sensitivity of the optical ambient light sensor. reduce. Therefore, it is difficult to achieve a balance between the receiving range and the transmittance.

Summary of the invention

The present application provides an electronic device having an ambient light detecting system that can increase the light receiving range of the ambient light sensor without affecting the light transmittance.

The ambient light detection system includes: an optical windowing, a micro-nano optical component and an ambient light sensor, the micro-nano optical component being located between the optical windowing and an ambient light sensor, the ambient light detecting system for illuminating light The optical fenestration is incident on the micro-nano optical element and is received by the ambient light sensor through the micro-nano optical element, the micro-nano optical element having a micro-nano optical structure for Change the direction of the incident light.

Optionally, the optical window is composed of a glass cover plate, an appearance ink and a light-shielding ink; the glass cover plate is coated with an appearance ink on a side of the micro-nano optical element; the light-shielding ink is coated on the Above the appearance ink, but the light-shielding ink is not coated in the optical window; the optical window is used to make light incident on the appearance ink The line is received by the ambient light sensor through the optical window; the incident light transmittance of the light-shielding ink is much smaller than the incident light transmittance of the appearance ink. Generally, electronic devices, such as mobile phones, have a variety of colors. In order to ensure the appearance, the optical window is kept consistent with the appearance. Generally, the glass cover at the optical window has an appearance ink. Alternatively, the appearance ink may not be applied.

Optionally, the area of the micro/nano optical element is larger than the area of the optical window opening. This ensures that all light entering the optical window is incident on the micro/nano optics.

Optionally, the micro/nano optical structure is a microlens array, and refers to a structure in which a plurality of microlenses having a size of micrometers are arranged in a certain manner on a highly transparent base material. The microlens includes a convex mirror or a concave mirror. Each microlens (convex or concave mirror) refracts the light incident on it, changing the direction of the incident light. Optionally, the effective focal length of the microlens may be 0.05 to 0.5 times the distance from the optical window to the ambient light sensor. The focal length of the microlens may be one. The microlenses can be arranged in a square or diamond shape. This arrangement ensures that the fill rate of the convex or concave mirror per unit area reaches a fill factor of π/4 (square arrangement) or π/2 (diamond row). cloth.

Optionally, the micro/nano optical structure is Fresnel. The Fresnel lens can collect the incident light from the left and right symmetrical angles of the lens to the ambient light sensor to increase the light receiving range. Optionally, the effective focal length of the Fresnel lens is about 0.05 to 0.5 times the distance from the optical window to the ambient light sensor, and the thickness of the Fresnel lens structure layer is 0.01 to 1 times the distance from the optical window to the ambient light sensor. . The Fresnel lens may include an inner ring and an outer ring, and the inner ring may have a round crown or a conical structure or a saw serrated structure. In the micro-nano process, the inner ring is easier to produce and process with a saw-tooth structure.

Optionally, the micro/nano optical structure is a microstructured diffusion plate, and the surface of the microstructure diffusion plate has a saw-tooth structure.

Optionally, the aspect ratio of the sawtooth structure of the incident surface of the microstructured diffusion plate is C2=h2/D2, and the aspect ratio of the sawtooth structure of the exiting surface is C1=h1/D1, C2 is greater than 0.5, and C1 is greater than 1.

Optionally, D2 is greater than D1.

Optionally, the micro/nano optical component comprises a glue layer, a base layer and a micro/nano optical structure layer, wherein one side of the base layer has the micro/nano optical structure layer, and the other side has the glue layer, so as to pass the A glue layer couples the micro/nano optical element to the optical window.

Optionally, the micro/nano optical component comprises a glue layer and a micro-nano optical structure layer, and the glue layer is coated on a glass cover plate on which the optical window is opened, and the micro-nano optical structure layer is engraved by The template of the micro/nano optical structure is obtained by applying pressure to the adhesive layer under external force and curing.

Optionally, the micro/nano optical component comprises a light guiding component and a micro/nano optical structural layer, and the micro/nano optical structural layer is formed on one side of the light guiding component by integral injection molding. Optionally, the light guiding component can be fixed between the optical window opening and the light receiver through the structural member and the body of the electronic device. The light guiding element has a T-shaped cross section.

Optionally, the material used for the micro/nano optical component has a light transmission greater than 90%.

The ambient light detecting system provided by the present application utilizes micro-nano optical components to realize the change of the incident optical path, and reduces the loss of incident light due to absorption and reflection, and the loss of light when transmitting through the micro-nano optical component becomes smaller. The range of light received by the light sensor is large.

DRAWINGS

1 is a schematic structural view of a prior art optical sensor system;

2 is a schematic view of an optical path of a prior art homochromatic ink diffusion example;

3 is a schematic view showing an optical window opening according to an embodiment of the present application;

4 is a schematic structural diagram of an electronic device with an ambient light detecting system provided by the present application;

5 is a schematic view of a light incident and exit path of a prior art homogenous ink and a micro/nano optical component of the present application;

6 is a perspective view of a microlens array according to an embodiment of the present application;

7 is a schematic diagram of light incident and exit paths of the microlens array provided by the present application;

Figure 8 is a side view and a plan view of a Fresnel lens provided by an embodiment of the present application;

9 is a schematic structural view of a Fresnel lens inner ring provided by an embodiment of the present application;

10 is a schematic diagram of light incident and exit paths of a Fresnel lens provided by an embodiment of the present application;

11 is a schematic structural view of a microstructure diffusion plate provided by an embodiment of the present application;

12 is a schematic diagram showing the size design of a microstructure diffusion plate provided by an embodiment of the present application;

13 is a schematic view showing the structure of an exit surface of another microstructure diffusion plate provided by an embodiment of the present application, and a light incident and exit path;

14 is a schematic structural diagram of a micro/nano optical component according to an embodiment of the present application;

15 is a schematic diagram of the structure and assembly of another micro-nano optical component according to an embodiment of the present application;

16 is a schematic structural diagram of still another micro-nano optical component according to an embodiment of the present application;

FIG. 17 is a schematic diagram of assembly of a light guiding element of an ambient light detecting system in an electronic device according to an embodiment of the present application.

detailed description

An embodiment of the present application provides an ambient light detecting system including at least one ambient light sensor, an optical windowing, and a micro/nano optical component. Depending on the ambient light detection system, ambient light entering the optical window is deflected by the micro-nano optical element at an angle and directed to the ambient light sensor. As shown in FIG. 3, for a consumer electronic device such as a cell phone, the optical window 300 can be composed of a glass cover 301, an appearance ink 302, and a light-shielding ink 303. The appearance ink is coated on the glass cover plate in the form of a full-surface coating to achieve an appearance color beauty and a shadow light sensor effect. The light-shielding ink is coated on the appearance ink, but the light-shielding ink is not applied in a certain area (window position) directly above the ambient light sensor, so that the transmittance of the incident light remains unchanged in the window-opening range, and The incident light transmittance of other areas with light-shielding ink can be reduced to 0.0001%. The purpose of appearance shielding and optical windowing is achieved by this ink coating.

As shown in FIG. 4, the present application provides an electronic device having an ambient light detecting system, including an ambient light detecting system, a cover glass, and a body. The ambient light detecting system includes the optical windowing 300, the micro/nano optical element 401, and the ambient light sensor 402 shown in FIG. Micro-nano optical element 401 is located between optical fenestration 300 and ambient light sensor 402. The ambient light passes through the appearance ink, enters the optical window 300, enters the micro-nano optical element 401 from the optical window 300, passes through the micro-nano optical element 401, and is received by the ambient light sensor 402. The micro/nano optical element 401 has a micro/nano optical structure 403 thereon. The diameter Φ1 of the optical window opening, the light receiving surface diameter Φ2 of the ambient light sensor, and the distance from the optical opening window to the light receiving surface of the ambient light sensor are d. The optical windowing, micro-nano optical components and ambient light sensor are on the same optical axis, and the size and distance between them can be determined according to the size requirements of the electronic device body where the ambient light detecting system is located.

The micro/nano optical structure deflects light entering the optical window at different angles, changes the direction of the incident light, and expands the light receiving range of the ambient light sensor. Figure 5 shows a schematic diagram of different optical paths using a homogenous ink and micro-nano optics. The light incident on the optical window at an angle θ does not change after passing through the homogenizing ink, and is not received by the ambient light sensor. The light incident on the optical window at the same angle θ is refracted by the micro-nano optical element and is deflected by an angle β to be received by the ambient light sensor. Therefore, the micro-nano optical element can be used to expand the light receiving range of the ambient light sensor, thereby increasing the FOV (field of view) of the ambient light sensor. Typically, the area of the micro-nano optical element is larger than the area of the optical fenestration to ensure as much as possible that all light entering the optical fenestration is incident on the micro-nano optical element. The micro-nano optical component can be made of a resin material having a light transmittance of more than 90%, such as PMMA (polymethyl methacrylate), PET (Polyethylene terephthalate, polyethylene terephthalate), PC ( Polycarbonates, polycarbonates, PA (Polyamide, polyamides), and the like.

The micro/nano optical structure of the present application can be designed into a variety of different structures. The following is an example of a structure such as a microlens array, a Fresnel lens, and a microstructured diffusion plate.

As shown in FIG. 6, the microlens array is an array of convex or concave mirrors of a micrometer scale in a certain order on a highly transparent base material. As shown in Fig. 7, each of the microlenses refracts the light incident thereon, so that the direction of the incident light can be changed. The convex mirror or the concave mirror in the microlens array can be applied in consumer electronic products, and the effective focal length of the lens can be between 0.05 and 0.5 times the distance d between the optical windowing and the ambient light sensor, and the focal length of the microlens can be 1. The micro-nano optical element can have a thickness between 50um and 0.5d. In order to achieve a better purpose of increasing the ambient light receiving range, the convex or concave mirrors can be arranged in a square or diamond shape, which ensures that the fill rate of the convex or concave mirror per unit area is filled. The factor is π/4 (square arrangement) or π/2 (diamond arrangement). The microlens array may have a periodic structure throughout the range of received light, which allows the intensity distribution of the ambient light sensor to be bilaterally symmetric without the need for alignment. Of course, a non-periodic structure can also be used in the specific implementation.

As shown in Fig. 8, the Fresnel lens structure includes a crown or a conical structure of the inner ring, and a Fresnel prism structure on the same surface. The Fresnel prism is different from the structure of the inner ring and has a ring shape. In one embodiment, the inner ring of the Fresnel lens may not be a crown or a cone, and the cross-sectional view may be a tooth shape as shown in FIG. As shown in Fig. 10, the incident light rays are changed after passing through the Fresnel lens surface. The Fresnel lens can deflect the incident light of the left and right symmetrical angles of the lens to the ambient light sensor to achieve the purpose of increasing the light receiving range. The Fresnel lens can make the light intensity distribution curve of the light sensor be bilaterally symmetric, which is beneficial to the reliability of light detection. In the Fresnel lens structure of the embodiment, the effective focal length is between 0.05 and 0.5 times the distance d between the optical windowing and the ambient light sensor, and the thickness of the Fresnel lens structure layer is between 0.01 d and 1 d.

The surface of the microstructured diffusion plate has a sawtooth structure. One side of the microstructured diffuser having a light exiting direction has a sawtooth structure, and one side of the incident light may be a flat surface or a sawtooth structure. As shown in Fig. 11, it is an example of a microstructured diffusion plate having a wider sawtooth structure on one side of the incident light and a thinner sawtooth structure on the side from which the light is emitted.

An example of the dimensional design of the microstructured diffusion plate is shown in Fig. 12. It is assumed that the aspect ratio of one of the sawtooth structures is C1 = h1/D1, and the aspect ratio of the other sawtooth structure is C2 = h2 / D2. Wherein, the surface corresponding to C2 is the light incident surface, h2 is the height of the sawtooth structure, and C2>0.5, which ensures that the light guide plate reaches the maximum transmittance and is in the visible wavelength range. It remains stable inside. The face corresponding to C1 is the outgoing surface, and C1>1. Among them, D2 can be between 1.0um and 2.0um, and D1 can be designed between 0.4um and 1.4um. If the cost is considered, the incident surface D2 can adopt a wide tooth, and the exit surface D1 can adopt a fine tooth, that is, D2 is larger than D1. The wider sawtooth structure on one side of the incident light is advantageous for processing and reducing the processing cost, while the side of the emitted light determines the refraction effect of the light, and the thinner structure ensures the receiving range of the light. Of course, the dimensions of the serrated structures of the two faces can be designed to be the same.

The sawtooth structure can be periodic or non-periodic. Figure 11 shows the periodic sawtooth structure. FIG. 13 is a schematic diagram showing the structure and optical path of another microstructure diffusing plate. The sawtooth structure on the side of the outgoing light is irregular, and the light is refracted by the irregular sawtooth structure and received by the ambient light sensor.

The above describes several implementations of the micro-nano optical structure. In practice, there may be other structures or a combination of several structures. For example, the middle part is a Fresnel lens surrounded by a microlens structure.

The structure and fabrication method of the micro/nano optical component including the micro/nano optical structure are described below.

As shown in FIG. 14, the micro/nano optical element may include a micro/nano optical structure layer and at least one base layer, wherein the base layer functions as a light guide, and the base layer material may be PMMA (polymethyl methacrylate). A resin material having a light transmittance of 90% or more, such as ester), PET (Polyethylene terephthalate), PC (Polycarbonates), and PA (Polyamide). In the manufacturing process, the optical embossing glue is first uniformly coated on the substrate layer, and the template engraved with the micro-nano optical structure (for example, a microlens array, a Fresnel lens or a microstructured diffusion plate) is used under the action of an external force. The embossing adhesive coated on the substrate layer is pressed into the structure on the stencil, and then the embossing adhesive is cured by UV light or heat curing. This is a simple, efficient and inexpensive way to produce. The micro-nano optical element composed of the base layer and the micro-nano structure layer can be coupled with the optical window by using OCA (Optically Clear Adhesive) optical glue or optical double-sided tape. The area of the micro/nano optical element is larger than the area of the optical fenestration to deflect all light entering the optical fenestration onto the ambient light sensor.

As shown in Figure 15, the micro/nano optical component can include a layer of micro-nano optical structural layer and a subbing layer. During the production process, the optical embossing glue can be directly coated on the optical opening of the glass cover plate for carrying the load, and the embossed adhesive is pressed into the template by the external force by the template engraved with the Fresnel structure. In the structure, the curing of the embossing adhesive is then effected by UV light or heat curing, and there is no substrate layer and optical coupling layer compared to the embodiment shown in FIG. The area of the micro-nano optical element is greater than or equal to the area of the optical fenestration to deflect all of the light entering the optical fenestration onto the light receiver.

As shown in FIG. 16, the micro/nano optical element may include at least one light guiding element and a micro/nano optical structure layer, and the micro/nano optical structure layer may be directly formed on the light guiding element by integral injection molding. The integral injection molding method may be that the high-transmittance plastic material which is completely melted by stirring at a certain temperature may be injected into the micro-nano-containing optical structure (for example, a microlens array, a Fresnel lens or a microstructure diffusion plate) by high pressure. The cavity is cooled and solidified to obtain an injection molded part with a replica cavity structure. The face with the micro/nano optical structure is on the same axis as the optical window and the light receiver.

As shown in FIG. 17, the light guiding element 1701 can be coupled to the glass cover optically by the OCA optical glue or the optical double-sided tape, and the light guiding element 1701 can be fixed by the structural member 1702 in the electronic device. The glass cover is between the optical window and the light receiver. The light guiding element may have a T-shaped structure, and the structural members on both sides are engaged on both sides of the T-shaped structure to fix the light guiding element in the electronic device body. The light-receiving surface (T-top) of the light guiding element is optically opened toward the glass cover and the area is not less than the optical window opening area, and the light guiding element emits light. The face (T-bottom) faces the light receiver face and has an area not less than the light receiver area.

The range in which the ambient light sensor receives the incident light and the intensity of the received incident light will affect the overall performance of the ambient light detection system. A good ambient light detection system needs to increase the range and intensity (light transmittance) of the received light. The technical solution of the present application utilizes the micro/nano optical structure to change the optical path of the incident light such that the incident light passes through the micro/nano optical structure and then the optical path is deflected toward the ambient light sensor, increasing the range of light received by the ambient light sensor. In some tests, the FOV of the existing homo-optical ink scheme is between 75° and 90°. Under the same conditions, the FOV of the micro-nano optical component of the present application is improved, and can reach 90°-130. ° Even higher. Reasonably designed micro-nano optical components have little reflection and absorption of light, reducing light loss and increasing the intensity of received light. Micro-nano processing technology such as imprinting, injection molding and other mature technologies can be used to realize large-scale and low-cost processing of micro-nano optical components. At the same time, the advantages of micro-nano optical components are small to solve the space requirements of consumer electronic products. The coupling of the micro/nano optics and the ambient light detection system can be achieved in a variety of mounting arrangements.

The technical solution of the present application is applicable to various application scenarios, and can be used, for example, in electronic devices such as mobile phones, PDAs, tablets, monitoring devices, GPS devices, and the like. The technical solution of the present application can also be applied to all scenarios using ambient light detection, such as building detection equipment, vehicle equipment and the like.

Claims

An electronic device having an ambient light detecting system, characterized in that

The ambient light detecting system includes: an optical windowing, a micro/nano optical element, and an ambient light sensor, the micro-nano optical element being located between the optical windowing and the ambient light sensor, the ambient light detecting system being used for Having light incident from the optical fenestration to the micro-nano optical element and through the micro-nano optical element is received by the ambient light sensor, the micro-nano optical element having a micro-nano optical structure, the micro-nano optical The structure is used to change the direction of the incident light.
The electronic device of claim 1 wherein the micro/nano optical structure comprises a microlens array, a Fresnel lens or a microstructured diffusion plate.
The electronic device according to claim 2, wherein the effective focal length of the microlens is 0.05 to 0.5 times the distance from the optical window to the ambient light sensor, and the focal length of the microlens is 1.
The electronic device according to claim 2, wherein the Fresnel lens has an effective focal length of 0.05 to 0.5 times the distance from the optical window to the ambient light sensor, and the thickness of the Fresnel lens structure layer is the optical Open the window to the ambient light sensor by 0.01 to 1 time.
The electronic device according to claim 2, wherein the surface of the microstructured diffusion plate has a sawtooth structure.
The electronic device according to claim 5, wherein the light incident surface and the light exit surface of the microstructure diffusion plate have a sawtooth structure.
The electronic device according to claim 1, wherein the aspect ratio of the sawtooth structure of the incident light surface of the microstructure diffusion plate is C2=h2/D2, and the aspect ratio of the sawtooth structure of the exiting light surface is C1=h1/D1. , C2 is greater than 0.5, and C1 is greater than 1.
The electronic device of claim 7 wherein D2 is greater than D1.
The electronic device according to any one of claims 1 to 8, wherein the micro/nano optical element comprises a light guiding element and a micro/nano optical structure layer, and the micro/nano optical structure layer is formed by integral injection molding. On one side of the light guiding element.
The electronic device according to claim 9, wherein the light guiding element is fixed between the optical window and the light receiver by the structural member and the body of the electronic device.
The electronic device according to any one of claims 1 to 9, wherein the material of the micro/nano optical element is a resin material having a light transmittance of 90% or more.