WO2018168250A1 - Light sensor - Google Patents

Abstract

This light sensor comprises: a substrate (10) having one surface (11), a first light-receiving element (12), and a second light-receiving element (13); a metallic light-shielding part (20); and a calculation unit (40) which performs a calculation process. The first light-receiving element is provided to the substrate such that at least a part of a first light-receiving surface is positioned in a first region (16), of the one surface, which is directly irradiated with light having passed through an opening but not having been reflected at all by the one surface or a reflection surface (22) on the one surface side of the light-shielding part, and the first light-receiving element outputs a first detection signal in accordance with a first intensity of light composed of: direct light that is directly incident on the first light-receiving surface through the opening; and indirect light that is indirectly incident thereon after being reflected by either one or both of the one surface and the reflection surface (22). The second light-receiving element is provided to the substrate such that the entirety of a second light-receiving surface is positioned in a second region (17), of the one surface, which excludes the first region, and the second light-receiving element outputs a second detection signal in accordance with a second intensity of the indirect light. A calculation unit eliminates a component of the indirect light that is included in the first intensity.

Description

Light sensor Cross-reference of related applications

This application is based on Japanese Patent Application No. 2017-48563 filed on March 14, 2015, the contents of which are incorporated herein by reference.

This disclosure relates to a light sensor.

2. Description of the Related Art Conventionally, an optical sensor including a substrate on which a plurality of light receiving elements are formed, and a light shielding film that is disposed above the substrate and defines a traveling direction of incident light with respect to each light receiving element is disclosed in, for example, Patent Document 1. Proposed in The light shielding film has a plurality of openings corresponding to the respective light receiving elements. Each opening is provided such that the traveling direction of incident light incident on each light receiving element is different.

JP2016-161458 A

In the conventional technology, each light receiving element receives not only direct light directly incident from the opening but also indirect light incident after being reflected from the substrate and the light shielding film after being incident from the opening. For this reason, the light receiving component has a broad characteristic including an indirect component of indirect light. That is, the direct component of direct light cannot be obtained with high accuracy from the light receiving component.

The present disclosure is intended to provide a light sensor that can acquire indirect components with high accuracy by removing indirect components contained in light receiving components.

According to one aspect of the present disclosure, the light sensor includes a first light receiving element that outputs the first detection signal corresponding to the intensity of light that is exposed on the first surface and the first light receiving surface. And a second light receiving element that outputs a second detection signal corresponding to the intensity of light incident on the second light receiving surface while exposing the second light receiving surface to one surface.

The light sensor has an opening that allows light to pass through, and includes a light shielding portion made of metal that is disposed above one surface of the substrate. The light sensor includes a calculation unit that receives the first detection signal and the second detection signal and performs calculation processing based on the first intensity and the second intensity.

In the first light receiving element, at least part of the first light receiving surface is directly irradiated with light that passes through the opening of one surface and is not reflected by the reflecting surface on one surface side of the light shielding portion. Direct light incident directly on the first light-receiving surface via the opening and indirect light reflected indirectly on either one or both of the reflection surface and the first light-receiving surface provided on the substrate so as to be located in one region; The first detection signal corresponding to the first intensity of the light including the light is output.

The second light receiving element is provided on the substrate so that the entire second light receiving surface is located in the second region of the one surface excluding the first region, and the second detection signal corresponding to the second intensity of the indirect light. Is output.

The calculation unit receives the first detection signal and the second detection signal, and calculates the difference between the first intensity and the second intensity, thereby removing the indirect light component included in the first intensity.

According to this configuration, since the second light receiving element is provided in the second region of the substrate where direct light does not reach, the second light receiving element acquires only indirect light components that do not include direct light components. Can do. For this reason, the indirect light component included in the first intensity can be removed by removing the indirect light component included in the light receiving component of the first light receiving element by the arithmetic unit. Therefore, the direct light component can be obtained with high accuracy.

The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the accompanying drawings,
FIG. 1 is a diagram illustrating a configuration of a light sensor according to a first embodiment of the present disclosure. FIG. 2 is a diagram for explaining components of direct light obtained by calculation of the calculation unit, FIG. 3 is a diagram for explaining a calculation result of a comparative example in which the indirect light component is not canceled, FIG. 4 is a diagram illustrating a configuration of a light sensor according to the second embodiment of the present disclosure. FIG. 5 is a diagram illustrating a configuration of a light sensor according to the third embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. The light sensor according to the present embodiment is applied to, for example, an auto light system that automatically turns on and off a headlight and a taillight of a vehicle.

As shown in FIG. 1, the light sensor includes a substrate 10, a light shielding unit 20, an insulating layer 30, and a calculation unit 40.

The substrate 10 has one surface 11. The one surface 11 can also be referred to as a surface. The substrate 10 is an n-type silicon substrate, for example. The substrate 10 includes a first light receiving element 12 and a second light receiving element 13. Each of the light receiving elements 12 and 13 is configured as a photodiode that detects the intensity of received light.

Specifically, a plurality of p-type regions are formed in the surface layer portion of the substrate 10, and each p-type region corresponds to each light receiving portion of each light receiving element 12, 13. The first light receiving surface 14 of the first light receiving element 12 and the second light receiving surface 15 of the second light receiving element 13 are exposed on the one surface 11 of the substrate 10.

Further, a cathode electrode (not shown) is formed on the back surface of the substrate 10, and an anode electrode (not shown) is provided in each p-type region. With such a configuration, each of the light receiving elements 12 and 13 outputs the light intensity as a voltage value intensity signal. The first light receiving element 12 outputs a first detection signal corresponding to the intensity of light incident on the first light receiving surface 14. The second light receiving element 13 outputs a second detection signal corresponding to the intensity of light incident on the second light receiving surface 15.

The light shielding unit 20 is a metal part disposed above the one surface 11 of the substrate 10. The light shielding portion 20 is formed as a metal film such as aluminum, for example. In addition, the light shielding unit 20 has an opening 21 that guides light to the one surface 11 of the substrate 10 through light.

The insulating layer 30 is provided between the one surface 11 of the substrate 10 and the light shielding part 20, on the opening part 21 of the light shielding part 20, and on the light shielding part 20 and the opening part 21. The insulating layer 30 has a property of allowing light to pass therethrough and has a function of preventing oxidation of the metal light shielding portion 20. The insulating layer 30 is an interlayer insulating film such as BPSG (Boron Phosphorate Silicate Glass). The substrate 10, the light shielding unit 20, and the insulating layer 30 are configured as one semiconductor chip.

The calculation unit 40 is a circuit unit that inputs the first detection signal of the first light receiving element 12 and the second detection signal of the second light receiving element 13 and performs calculation processing based on the first intensity and the second intensity. The calculation unit 40 calculates the difference between the first intensity and the second intensity, thereby canceling the light-receiving component having the second intensity included in the first intensity. The calculation unit 40 may be formed on the substrate 10 or may be formed on a semiconductor chip different from the substrate 10.

The above is the overall configuration of the light sensor according to the present embodiment. The light sensor includes a case (not shown), and is packaged by accommodating the above-described components. The light sensor is mounted on, for example, a vehicle dashboard.

Next, the arrangement of the light receiving elements 12 and 13 on the substrate 10 will be described. First, there is a first region 16 and a second region 17 on one surface 11 of the substrate 10.

In the first region 16, the light passing through the opening 21 of the light shielding part 20 in the one surface 11 of the substrate 10 is never reflected by the one surface 11 of the substrate 10 and the reflecting surface 22 on the one surface 11 side of the light shielding part 20. This is the area that is directly irradiated. The range of the first region 16 is determined by the refractive index of the insulating layer 30, the size of the opening 21, the position of the light shielding unit 20 with respect to the one surface 11 of the substrate 10, and the like.

On the other hand, the second region 17 is a region of the one surface 11 of the substrate 10 excluding the first region 16. That is, the second region 17 is a region where light that has passed through the opening 21 of the light shielding unit 20 is not directly irradiated.

The first light receiving element 12 is provided on the substrate 10 such that a part of the first light receiving surface 14 is located in the first region 16. As a result, the first light receiving element 12 has either direct light directly incident on the first light receiving surface 14 through the opening 21 of the light shielding unit 20 and one surface 11 of the substrate 10 or the reflection surface 22 of the light shielding unit 20 or It receives light including indirect light that is reflected and indirectly incident by both. The indirect light may reflect the surface 11 and the reflecting surface 22 many times. Accordingly, the first light receiving element 12 outputs a first detection signal corresponding to the first intensity of light including direct light and indirect light.

The second light receiving element 13 is provided on the substrate 10 so that the entire second light receiving surface 15 is located in the second region 17. Thereby, the second light receiving element 13 receives the light reflected by the one surface 11 of the substrate 10 or the reflecting surface 22 of the light shielding portion 20. That is, the second light receiving element 13 receives light that does not include direct light. Accordingly, the second light receiving element 13 outputs a second detection signal corresponding to the second intensity of the indirect light.

In the present embodiment, the second light receiving element 13 has the entire second light receiving surface 15 provided in the second region 17 on the outer periphery of the first region 16. That is, the second light receiving element 13 is disposed close to the first light receiving element 12. Accordingly, the second light receiving element 13 can receive substantially the same indirect light as the indirect light received by the first light receiving element 12.

Subsequently, the operation of the calculation unit 40 will be described. The calculation unit 40 inputs the first detection signal and the second detection signal from each of the light receiving elements 12 and 13 at any time or at a predetermined timing. And the calculating part 40 calculates the difference of 1st intensity | strength and 2nd intensity | strength. If the first intensity is PD1 and the second intensity is PD2, the calculation unit 40 calculates PD1-PD2. Thereby, the component of the indirect light included in the first intensity is removed. *

As shown in FIG. 2, since the first intensity PD1 includes components of direct light and indirect light, the component of direct light is buried in the component of indirect light. However, the second intensity PD2 does not include a direct light component, but includes only an indirect light component. Therefore, the light component can be directly extracted from the first intensity PD1 by the calculation of PD1-PD2. In order to improve the accuracy of indirect light cancellation, it is preferable that the light receiving surfaces 14 and 15 of the light receiving elements 12 and 13 have the same size.

As a comparative example, a configuration in which two openings 21 are provided in the light shielding part 20 and two light receiving elements corresponding to the respective openings 21 are provided in the substrate 10 can be considered. One light receiving element is disposed in the first region 16 in which at least a part of the light receiving surface is set by the one opening 21. The same applies to the other light receiving element.

In the configuration of such a comparative example, the direct light component of the light received by each light receiving element is different, and the indirect light component is also different. When the third intensity received by one of the light receiving elements is PD3, the third intensity PD3 includes a direct light component α and an indirect light component β. If the fourth intensity received by the other light receiving element is PD4, the fourth intensity PD4 includes a direct light component γ and an indirect light component σ. Even if PD3-PD4 is calculated to cancel the indirect light component of each light receiving element, the indirect light component remains without being canceled.

As shown in FIG. 3, the PD3-PD4 components have a broad characteristic in which the components of indirect light remain. Therefore, in the configuration in which the output of each light receiving element corresponding to each opening 21 is calculated as in the comparative example, the indirect light component cannot be canceled with high accuracy.

In contrast to the comparative example, in the present embodiment, the second light receiving element 13 is provided in the second region 17 of the substrate 10 where direct light does not reach. Thereby, only the component of indirect light which does not contain the component of direct light by the 2nd light receiving element 13 is acquirable. For this reason, the component of the indirect light included in the first intensity can be removed by the calculation process of the calculation unit 40. Therefore, the direct light component can be obtained with high accuracy.

As a modification, on one surface 11 of the substrate 10, a region excluding the light receiving surfaces 14 and 15 of the light receiving elements 12 and 13 may be configured as a metal surface. Thereby, it is possible to reduce the influence of attenuation of the indirect light component due to the distance of the light traveling in the surface direction of the one surface 11 of the substrate 10.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIG. 4, the light shielding unit 20 includes a first opening 23 and a second opening 24 as the opening 21. Each opening 23, 24 is separated.

And the 1st light receiving element 12 is provided in the board | substrate 10 so that a part of 1st light-receiving surface 14 may be located in the 1st area | region 16 set by the 1st opening part 23. FIG. On the other hand, in the second light receiving element 13, the entire second light receiving surface 15 is provided in the second region 17 on the outer periphery of the first region 16 set by the second opening 24.

As described above, the light receiving elements 12 and 13 may be arranged on the substrate 10 in association with the different openings 23 and 24 without being related to the first region 16 set by the one opening 21.

(Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. As shown in FIG. 5, the first light receiving element 12 may be provided on the substrate 10 such that the entire first light receiving surface 14 is located in the first region 16. Thereby, the 1st light receiving element 12 can receive direct light reliably.

(Other embodiments)
The configuration of the light sensor described in each of the above embodiments is merely an example, and the present disclosure is not limited to the configuration described above, and other configurations that can realize the present disclosure may be employed. For example, the insulating layer 30 may not be formed on the light shielding unit 20.

Alternatively, a configuration in which a plurality of first light receiving elements 12 are provided on the substrate 10 and one second light receiving element 13 is provided on the substrate 10 may be employed. That is, the second light receiving element 13 may be commonly used for the plurality of first light receiving elements 12. A plurality of sets of the first light receiving element 12 and the second light receiving element 13 may be provided on the substrate 10. On the other hand, a plurality of second light receiving elements 13 may be provided for one first light receiving element 12.

As mentioned above, although the embodiment, configuration, and aspect of the light sensor according to one aspect of the present disclosure have been illustrated, the embodiment, configuration, and aspect according to the present disclosure are limited to the above-described embodiments, configurations, and aspects. It is not a thing. For example, embodiments, configurations, and aspects obtained by appropriately combining technical sections disclosed in different embodiments, configurations, and aspects are also included in the scope of the embodiments, configurations, and aspects according to the present disclosure.

Claims (5)

A first light receiving element (12) that outputs a first detection signal corresponding to an intensity of light incident on the first light receiving surface while the first surface (11) and the first light receiving surface (14) are exposed on the one surface A substrate (10) having a second light receiving element (13) for exposing a second light receiving surface (15) to the one surface and outputting a second detection signal corresponding to the intensity of light incident on the second light receiving surface. When,
A light-shielding portion (20) made of metal having an opening (21) for transmitting light and disposed above the one surface of the substrate;
A calculation unit (40) for inputting the first detection signal and the second detection signal and performing a calculation process based on the first intensity and the second intensity;
With
In the first light receiving element, at least a part of the first light receiving surface is such that light passing through the opening of the one surface is once reflected on the one surface and the reflecting surface (22) on the one surface side of the light shielding portion. The direct light directly incident on the first light receiving surface through the opening, the one surface, and the reflecting surface are provided on the substrate so as to be positioned in the first region (16) that is directly irradiated without being reflected. (22) outputting the first detection signal corresponding to the first intensity of the light including the indirect light that is indirectly reflected and reflected by either or both of (22),
The second light receiving element is provided on the substrate so that the entire second light receiving surface is located in a second region (17) of the one surface excluding the first region, Outputting the second detection signal corresponding to two intensities;
The calculation unit inputs the first detection signal and the second detection signal, and calculates a difference between the first intensity and the second intensity, thereby calculating a component of the indirect light included in the first intensity. Light sensor to be removed. The light-shielding portion has a first opening (23) and a second opening (24) as the opening,
The first light receiving element is provided on the substrate so that at least a part of the first light receiving surface is located in the first region set by the first opening,
2. The light sensor according to claim 1, wherein the second light receiving element is provided in the second region of the outer periphery of the first region set by the second opening. The light sensor according to claim 1, wherein the second light receiving element is provided in the second region on the outer periphery of the first region set by the opening. The light sensor according to any one of claims 1 to 3, wherein an area of the one surface excluding the first light receiving surface and the second light receiving surface is configured as a metal surface. The light sensor according to any one of claims 1 to 4, wherein the first light receiving element is provided on the substrate so that the entire first light receiving surface is located in the first region.

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