Narrowband optical filter and optical sensing device

Abstract

The utility model discloses a narrowband optical filter, comprising a glass substrate having a front surface and a back surface; the multi-film filtering structure is arranged on the front surface of the glass substrate; and the corrosion-resistant film layer is arranged on the surface of one side, far away from the glass substrate, of the multi-film-layer light filtering structure. The narrow-band optical filter provided by the utility model has relatively high anti-corrosion performance. The utility model further discloses an optical sensing device which comprises the narrow-band optical filter.

Description

Technical Field

[0001] The utility model relates to the field of optical elements, in particular to a narrow-band filter and an optical sensing device. Background Art

[0002] Optical sensors such as optical fingerprint sensors, image sensors, and laser ranging sensors achieve sensing functions by sensing and identifying specific light rays. In order to improve the recognition accuracy of optical sensors, a narrow-band filter is generally provided in front of the optical sensors to filter out stray light (especially infrared light) and reduce the interference of stray light on the light rays to be identified.

[0003] For example, a Chinese patent with the application number CN201911374758.0 discloses a filter for under-screen fingerprint recognition, including a substrate. Film system structure layers are plated on both sides of the substrate. The film system structure layer is composed of several sub-film layers stacked together, and each sub-film layer is plated with a high-refractive-index material layer and a low-refractive-index material layer alternately stacked. The film system structure layer in this filter can filter out stray light and prevent the recognition chip from being seen in the case of a black screen.

[0004] However, as the outermost layer, the filter of an optical fingerprint sensor, etc., is in long-term contact with fingers, and dirt, grease, sweat, etc. on the fingers are likely to corrode the film system structure layer in the filter. Summary of the Utility Model

[0005] In order to solve the above-mentioned deficiencies of the prior art, the utility model provides a narrow-band filter with high corrosion resistance.

[0006] The utility model also provides an optical sensing device including the above-mentioned narrow-band filter.

[0007] The technical problems to be solved by the utility model are realized through the following technical solutions:

[0008] A narrow-band filter includes:

[0009] A glass substrate having a front surface and a back surface;

[0010] A multi-film layer filter structure disposed on the front surface of the glass substrate;

[0011] A corrosion-resistant film layer disposed on the surface of the multi-film layer filter structure away from the glass substrate.

[0012] Further, the corrosion-resistant film layer is a molybdenum-chromium alloy film layer with a thickness of 20-50 nm.

[0013] Furthermore, the multi-layer film filter structure is composed of several sub-film layers stacked together, and each sub-film layer is composed of a high-refractive-index film layer and a low-refractive-index film layer stacked alternately.

[0014] Furthermore, the sub-film layers are, from the side close to the glass substrate to the side far from the glass substrate, a low-refractive-index film layer, a high-refractive-index film layer, and a low-refractive-index film layer in sequence, wherein the thickness of the low-refractive-index film layer is half of the thickness of the high-refractive-index film layer.

[0015] Furthermore, the high-refractive-index film layer is a titanium dioxide film layer, a titanium trioxide film layer, a tantalum pentoxide film layer, or a niobium pentoxide film layer.

[0016] Furthermore, the low-refractive-index film layer is a silicon dioxide film layer, an aluminum oxide film layer, or a magnesium fluoride film layer.

[0017] Furthermore, the thickness of the high-refractive-index film layer is 7 nm - 155 nm, and the thickness of the low-refractive-index film layer is 15 nm - 195 nm.

[0018] Furthermore, the narrowband filter also includes an interface layer, and the interface layer is disposed between the glass substrate and the multi-layer film filter structure.

[0019] Furthermore, the interface layer is a polysiloxane film layer, and its thickness is 50 - 70 nm.

[0020] An optical sensing device includes an optical sensor and the above-mentioned narrowband filter, and the optical sensor is disposed on the back surface of the narrowband filter.

[0021] The utility model has the following beneficial effects: The narrowband filter of the utility model is provided with the corrosion-resistant film layer on the surface of the multi-layer film filter structure. As the outermost layer of the narrowband filter, the corrosion-resistant film layer can block external corrosive substances, prevent the multi-layer film filter structure from being corroded due to contact with external corrosive substances, and improve the anti-corrosion performance of the product. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the stacking structure of the narrowband filter provided by the utility model.

[0023] Figure 2 It is a schematic diagram of the stacking structure of the multi-layer film filter structure in the narrowband filter provided by the utility model.

[0024] Figure 3 It is a schematic diagram of the stacking structure of another narrowband filter provided by the utility model.

[0025] Figure 4Schematic diagram of the stacked structure of the optical sensing device provided by the present utility model. Detailed implementation mode

[0026] The present utility model will be described in detail below with reference to the drawings and embodiments. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present utility model, and should not be construed as a limitation of the present utility model.

[0027] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present utility model.

[0028] In addition, the terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", "third" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality of" means two or more unless otherwise specifically defined.

[0029] In the present utility model, unless otherwise clearly specified and defined, the terms "installation", "connection", "connection", "fixation", "setting", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may also be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0030] Embodiment 1

[0031] As Figure 1 shown, a narrow-band filter includes:

[0032] A glass substrate 21 having a front surface and a back surface;

[0033] A multi-layer film filter structure 22 disposed on the front surface of the glass substrate 21;

[0034] The corrosion-resistant film layer 23 is disposed on the surface of the multi-film layer filter structure 22 away from the glass substrate 21.

[0035] In the narrowband filter of the present utility model, the corrosion-resistant film layer 23 is disposed on the surface of the multi-film layer filter structure 22. The corrosion-resistant film layer 23 serves as the outermost layer of the narrowband filter, which can block external corrosive substances, prevent the multi-film layer filter structure 22 from being corroded due to contact with external corrosive substances, and improve the anti-corrosion performance of the product.

[0036] The narrowband filter of the present utility model is preferably used as the filter of an optical fingerprint recognition sensor. However, filters for various products also have anti-corrosion requirements. Therefore, the application scope of the present utility model should not be limited to the optical fingerprint recognition sensor, and it can also be used for other types of optical sensors.

[0037] Preferably, the corrosion-resistant film layer 23 is a molybdenum-chromium alloy film layer with a thickness of 20 - 50 nm.

[0038] Although the molybdenum-chromium alloy film layer is made of alloy material, when its thickness is less than 80 nm, it can exhibit a certain degree of light transmittance. When its thickness is between 20 - 50 nm, it can meet the requirements of both light transmittance and corrosion resistance. In addition to the corrosion-resistant characteristics, the molybdenum-chromium alloy film layer also has high temperature resistance, oxidation resistance, and wear resistance, which can improve the high temperature resistance, oxidation resistance, and wear resistance of the narrowband filter at the same time.

[0039] As Figure 2 shown, the multi-film layer filter structure 22 is composed of a number of sub-film layers 22a stacked together, and each sub-film layer 22a is composed of a high refractive index film layer 221 and a low refractive index film layer 222 stacked alternately.

[0040] The multi-film layer filter structure 22 of the present utility model selects different refractive index materials as the high refractive index film layer 221 and the low refractive index film layer 222 respectively, uses the refractive index difference between the high refractive index film layer 221 and the low refractive index film layer 222 to reflect specific wavelength light, and reasonably designs the thicknesses of the high refractive index film layer 221 and the low refractive index film layer 222, so that the optical path difference between two adjacent reflected lights satisfies the light interference condition and then cancels each other out to achieve the purpose of filtering specific wavelength light; and each sub-film layer 22a is responsible for filtering different wavelength light, and finally realizes the filtering of light in a certain specific wavelength range.

[0041] The sub-film layer 22a is, from the side close to the glass substrate 21 to the side far from the glass substrate 21, a low refractive index film layer 222, a high refractive index film layer 221, and a low refractive index film layer 222 in sequence, wherein the thickness of the low refractive index film layer 222 is half of the thickness of the high refractive index film layer 221.

[0042] In this embodiment, the high refractive index film layer 221 can be but is not limited to a titanium dioxide film layer, a titanium trioxide film layer, a tantalum pentoxide film layer, or a niobium pentoxide film layer, and the thickness of the high refractive index film layer 221 is 7 nm - 155 nm; the low refractive index film layer 222 can be but is not limited to a silicon dioxide film layer, an aluminum oxide film layer, or a magnesium fluoride film layer, and the thickness of the low refractive index film layer 222 is 15 nm - 195 nm.

[0043] Through the above settings, the wavelength range of the red and orange light that can be filtered is within 625 - 780 nm, the wavelength range of the ultraviolet cut-off is within 350 - 400 nm, and the wavelength range that needs to penetrate is within 430 - 560 nm. Among them, the selected ultraviolet cut-off T = 50% band is 415 nm, the red and orange light cut-off T = 50% band is 570 - 605 nm, and the actual curve satisfies that in the infrared band AOI = 0 - 30 deg, OD of 780 - 1100 nm is greater than 4, mainly to ensure the infrared light cut-off depth near 850 nm.

[0044] Embodiment Two

[0045] As an optimized solution of Embodiment One, in this embodiment, as Figure 3 shown, the narrowband filter further includes an interface layer 24, and the interface layer 24 is disposed between the glass substrate 21 and the multi-film layer filter structure 22.

[0046] The narrowband filter of the present utility model improves the interface performance between the glass substrate 21 and the multi-film layer filter structure 22, enhances the adhesion ability between the glass substrate 21 and the multi-film layer filter structure 22, and avoids the multi-film layer filter structure 22 from peeling off the glass substrate 21 after long-term use by disposing the interface layer 24 between the glass substrate 21 and the multi-film layer filter structure 22.

[0047] Preferably, the interface layer 24 is a polysiloxane film layer, and its thickness is 50 - 70 nm.

[0048] Embodiment Three

[0049] As Figure 4 shown, an optical sensing device includes an optical sensor 10 and the narrowband filter 20 described in Embodiment One or Embodiment Two, and the optical sensor 10 is disposed on the back surface of the narrowband filter 20.

[0050] In this embodiment, the optical sensor 10 is adhesively fixed to the back surface of the glass substrate 21 through the OCA optical adhesive 30.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and not to limit them. Although the embodiments of the present invention have been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the embodiments of the present invention can still be modified or equivalently replaced, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A narrow-band filter, characterized in that, Comprising: A glass substrate having a front side and a back side; A multi-layer film filter structure disposed on the front side of the glass substrate; A corrosion-resistant film layer disposed on the surface of the multi-layer film filter structure on the side away from the glass substrate; Wherein, the corrosion-resistant film layer is a molybdenum-chromium alloy film layer with a thickness of 20 - 50 nm.

2. The narrowband optical filter according to claim 1, wherein The multi-layer film filter structure is composed of a number of sub-film layers stacked together, and each sub-film layer is composed of alternately stacked high-refractive-index film layers and low-refractive-index film layers.

3. The narrowband optical filter according to claim 2, characterized in that, The sub-film layer is, in sequence from the side close to the glass substrate to the side away from the glass substrate, a low-refractive-index film layer, a high-refractive-index film layer, and a low-refractive-index film layer, wherein the thickness of the low-refractive-index film layer is half of the thickness of the high-refractive-index film layer.

4. The narrowband optical filter according to claim 2, wherein The high-refractive-index film layer is a titanium dioxide film layer, a titanium trioxide film layer, a tantalum pentoxide film layer, or a niobium pentoxide film layer.

5. The narrowband optical filter according to claim 2, wherein The low-refractive-index film layer is a silicon dioxide film layer, an aluminum oxide film layer, or a magnesium fluoride film layer.

6. The narrowband optical filter according to claim 2, wherein, The thickness of the high-refractive-index film layer is 7 nm - 155 nm, and the thickness of the low-refractive-index film layer is 15 nm - 195 nm.

7. The narrowband filter according to claim 1, characterized in that, The narrowband filter further includes an interface layer disposed between the glass substrate and the multi-layer film filter structure.

8. The narrowband optical filter according to claim 7, wherein, The interface layer is a polysiloxane film layer with a thickness of 50 - 70 nm.

9. An optical sensing device, characterized in that, Comprising an optical sensor and the narrowband filter according to claim 1, wherein the optical sensor is disposed on the back side of the narrowband filter.

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