JP6760152B2 - Light sensor - Google Patents

Description

The present invention relates to a light sensor.

Conventionally, an optical sensor including a substrate on which a plurality of light receiving elements are formed and a light shielding film arranged above the substrate and defining a traveling direction of incident light with respect to each light receiving element has been described, for example, Patent Document 1. Proposed in. The light-shielding film has a plurality of openings corresponding to each light-receiving element. Each opening is provided so that the traveling direction of the incident light incident on each light receiving element is different.

Japanese Unexamined Patent Publication No. 2016-161458

However, in the above-mentioned conventional technique, each light receiving element receives not only the direct light directly incident from the opening but also the indirect light reflected from the substrate or the light-shielding film after being incident from the opening. Therefore, the light receiving component has a broad characteristic including the indirect component of indirect light. That is, it is not possible to accurately obtain the direct component of direct light from the light receiving component.

In view of the above points, an object of the present invention is to provide a light sensor capable of removing an indirect component contained in a light receiving component and acquiring a direct component with high accuracy.

In order to achieve the above object, in the invention according to claim 1, the light sensor has one surface (11) and a first light receiving surface (14) exposed on one surface and the intensity of light incident on the first light receiving surface. The first light receiving element (12) and the second light receiving surface (15) that output the corresponding first detection signal are exposed on one surface, and the second detection signal corresponding to the intensity of the light incident on the second light receiving surface is output. It is provided with a substrate (10) having a second light receiving element (13).

The light sensor has an opening (21) that allows light to pass through, and includes a metal light-shielding portion (20) arranged above one surface of the substrate. The light sensor includes a calculation unit (40) that inputs a first detection signal and a second detection signal and performs calculation processing based on the first detection signal and the second detection signal .

In the first light receiving element, at least a part of the first light receiving surface directly irradiates the light passing through the opening on one surface and the reflecting surface (22) on one surface side of the light shielding portion without being reflected even once. It is provided on the substrate so as to be located in the first region (16), and is indirectly reflected by one or both of the direct light directly incident on the first light receiving surface and one surface and the reflecting surface through the opening. The first detection signal corresponding to the first intensity of the light including the indirect light incident on 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 (17) excluding the first region of one surface, and the second light receiving element corresponds to the second intensity of indirect light. 2 Output the detection signal.

The calculation unit inputs the first detection signal and the second detection signal, and calculates the difference between the first intensity and the second intensity to remove the component of indirect light contained in the first intensity . .. One surface is configured as a metal surface in a region excluding the first light receiving surface and the second light receiving surface.

According to this, since the second light receiving element is provided in the second region of the substrate where the direct light does not reach, the second light receiving element can acquire the component of only indirect light which does not contain the component of direct light. .. Therefore, the component of the indirect light contained in the first intensity can be removed by removing the component of the indirect light contained in the light receiving component of the first light receiving element by the calculation unit. Therefore, the component of direct light can be acquired with high accuracy.

In addition, the reference numerals in parentheses of each means described in this column and the scope of claims indicate the correspondence with the specific means described in the embodiment described later.

It is a figure which showed the structure of the light sensor which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the component of the direct light obtained by the calculation of the calculation part. It is a figure for demonstrating the calculation result of the comparative example in which the component of indirect light is not canceled. It is a figure which showed the structure of the light sensor which concerns on 2nd Embodiment of this invention. It is a figure which showed the structure of the light sensor which concerns on 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the same or equal parts are designated by the same reference numerals in the drawings.

(First Embodiment)
Hereinafter, the first embodiment of the present invention 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 the headlights and tail lights 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 side 11. The substrate 10 is, for example, an n-type silicon substrate. Further, the substrate 10 has 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 the received light.

Specifically, a plurality of p-type regions are formed on the surface layer portion of the substrate 10, and each p-type region corresponds to each light receiving portion of each of the light receiving elements 12 and 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 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-shaped region. With such a configuration, each of the light receiving elements 12 and 13 outputs the intensity of light as an intensity signal of a voltage value. The first light receiving element 12 outputs a first detection signal according to the intensity of light incident on the first light receiving surface 14. The second light receiving element 13 outputs a second detection signal according to the intensity of the light incident on the second light receiving surface 15.

The light-shielding portion 20 is a metal component arranged above one surface 11 of the substrate 10. The light-shielding portion 20 is formed as a metal film such as aluminum. Further, the light-shielding portion 20 has an opening 21 that guides light to one surface 11 of the substrate 10 by passing light.

The insulating layer 30 is provided between one surface 11 of the substrate 10 and the light-shielding portion 20, above the opening 21 of the light-shielding portion 20, and the light-shielding portion 20 and the opening 21. The insulating layer 30 has a property of allowing light to pass through, and has a function of preventing oxidation of the metal light-shielding portion 20 and the like. The insulating layer 30 is an interlayer insulating film such as BPSG. The substrate 10, the light-shielding portion 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 cancels the light receiving component of the second intensity included in the first intensity by calculating the difference between the first intensity and the second 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 this embodiment. The light sensor includes a case (not shown) and is packaged by accommodating each of the above configurations. Further, the light sensor is mounted on, for example, a dashboard of a vehicle.

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

In the first region 16, the light passing through the opening 21 of the light-shielding portion 20 of the one-sided portion 11 of the substrate 10 is never reflected by the reflecting surface 22 of the one-sided surface 11 of the substrate 10 and the one-sided 11 side of the light-shielding portion 20. Is the area that is directly irradiated to. 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 portion 20 with respect to one surface 11 of the substrate 10, and the like.

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

The first light receiving element 12 is provided on the substrate 10 so 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 receives direct light directly incident on the first light receiving surface 14 through the opening 21 of the light shielding portion 20, and one of the one surface 11 of the substrate 10 and the reflecting surface 22 of the light shielding portion 20. It receives light including indirect light that is reflected by both and indirectly incident. The indirect light may reflect the one surface 11 and the reflecting surface 22 many times. Therefore, the first light receiving element 12 outputs the first detection signal corresponding to the first intensity of the light including the direct light and the 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. As a result, 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. Therefore, the second light receiving element 13 outputs the second detection signal corresponding to the second intensity of the indirect light.

Further, in the present embodiment, the entire second light receiving surface 15 of the second light receiving element 13 is provided in the second region 17 on the outer periphery of the first region 16. That is, the second light receiving element 13 is arranged close to the first light receiving element 12. As a result, 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 the light receiving elements 12 and 13 at any time or at a predetermined timing. Then, the calculation unit 40 calculates the difference between the first intensity and the second intensity. Assuming that the first intensity is PD1 and the second intensity is PD2, the calculation unit 40 calculates PD1-PD2. As a result, the component of indirect light contained in the first intensity is removed.

As shown in FIG. 2, since the first intensity PD1 contains each component 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 contain a direct light component and is composed only of 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 canceling indirect light, 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, it is conceivable that the light-shielding portion 20 is provided with two openings 21 and the substrate 10 is provided with two light receiving elements corresponding to the respective openings 21. One light receiving element is arranged in the first region 16 where at least a part of the light receiving surface is set by 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. Assuming that the third intensity received by one of the light receiving elements is PD3, the third intensity PD3 contains a component α of direct light and a component β of indirect light. Assuming that 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 components of PD3-PD4 have a broad characteristic in which the component of indirect light remains. 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 component of indirect light cannot be canceled accurately.

In contrast to the comparative example, the present embodiment has a configuration in which the second light receiving element 13 is provided in the second region 17 of the substrate 10 where the direct light does not reach. As a result, the second light receiving element 13 can acquire a component of only indirect light that does not contain a component of direct light. Therefore, the component of indirect light contained in the first intensity can be removed by the arithmetic processing of the arithmetic unit 40. Therefore, the component of direct light can be acquired with high accuracy.

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

(Second Embodiment)
In this embodiment, a part different from the first embodiment will be described. As shown in FIG. 4, the light-shielding portion 20 has a first opening 23 and a second opening 24 as the opening 21. The openings 23 and 24 are separated from each other.

The first light receiving element 12 is provided on the substrate 10 so that a part of the first light receiving surface 14 is located in the first region 16 set by the first opening 23. 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 different openings 23 and 24 without being related to the first region 16 set by one opening 21.

(Third Embodiment)
In this embodiment, a part 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 so that the entire first light receiving surface 14 is located in the first region 16. As a result, the first light receiving element 12 can reliably receive the direct light.

(Other embodiments)
The configuration of the light sensor shown in each of the above embodiments is an example, and the configuration is not limited to the configuration shown above, and other configurations capable of realizing the present invention may be used. For example, the insulating layer 30 does not have to be formed on the light-shielding portion 20.

Further, a plurality of first light receiving elements 12 may be provided on the substrate 10, and one second light receiving element 13 may be provided on the substrate 10. That is, the second light receiving element 13 may be commonly used for the plurality of first light receiving elements 12. Of course, a plurality of pairs 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.

10 Substrate 11 One side 12 First light receiving element 13 Second light receiving element 14 First light receiving surface 15 Second light receiving surface 20 Light shielding part 21 Opening 40 Calculation unit

Claims (4)

One surface (11), a first light receiving element (12) that exposes the first light receiving surface (14) and outputs a first detection signal according to the intensity of light incident on the first light receiving surface, and A substrate (10) having a second light receiving element (13) that exposes the second light receiving surface (15) to the one surface and outputs a second detection signal according to the intensity of light incident on the second light receiving surface. When,
A metal shading portion (20) having an opening (21) for passing light and arranged above the one surface of the substrate.
An arithmetic unit (40) that inputs the first detection signal and the second detection signal and performs arithmetic processing based on the first detection signal and the second detection signal .
With
In the first light receiving element, at least a part of the first light receiving surface is once on the one surface, the light passing through the opening is reflected on the one surface and the one surface side of the light shielding portion (22). Direct light that is provided on the substrate so as to be located in the first region (16) that is directly irradiated without being reflected, and is directly incident on the first light receiving surface through the opening, and the one surface and the reflecting surface. The first detection signal corresponding to the first intensity of the light including the indirect light reflected by one or both of the above and indirectly incident 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 (17) of the one surface excluding the first region, and the indirect light is the first. 2 Output the second detection signal according to the intensity,
The calculation unit inputs the first detection signal and the second detection signal, and calculates the difference between the first intensity and the second intensity to obtain the component of the indirect light contained in the first intensity. It is designed to be removed,
The one surface is a light sensor in which a region excluding the first light receiving surface and the second light receiving surface is formed as a metal surface. 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.
The light sensor according to claim 1, wherein the second light receiving element is the light sensor according to claim 1, wherein the entire second light receiving surface is provided in the second region on 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 the light sensor according to claim 1, wherein the entire second light receiving surface 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 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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