JP2018151294A - Light sensor - Google Patents

Abstract

Provided is a light sensor capable of accurately acquiring a direct component by removing an indirect component contained in a light receiving component. In a first light receiving element, a part of a first light receiving surface is irradiated directly with light passing through an opening of one surface without being reflected by the one surface and the reflecting surface. It is provided on the substrate 10 so as to be located in the first region 16. The first light receiving element 12 is a first light that includes direct light that directly enters the first light receiving surface 14 and indirect light that is indirectly incident after being reflected by one or both of the one surface 11 and the reflecting surface 22. A first detection signal corresponding to the intensity is output. 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 of the one surface 11 excluding the first region 16, and is in accordance with the second intensity of indirect light. The second detection signal is output. The calculation unit 40 calculates a difference between the first intensity and the second intensity, and removes the indirect light component included in the first intensity. [Selection] Figure 1

Description

  The present invention 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.

Japanese Patent Laid-Open No. 2006-161458

  However, in the above conventional technique, each light receiving element receives not only direct light directly incident from the opening but also indirect light that is incident 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.

  An object of this invention is to provide the light sensor which removes the indirect component contained in a light reception component, and can acquire a direct component with sufficient precision in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, the light sensor is configured such that the one surface (11) and the first light receiving surface (14) are exposed on one surface and the intensity of light incident on the first light receiving surface. The first light receiving element (12) that outputs a first detection signal corresponding to the first light receiving element and the second light receiving surface (15) are exposed on one surface, and the second detection signal is output according to the intensity of light incident on the second light receiving surface. And a second light receiving element (13).

  The light sensor has an opening (21) through which light passes, and includes a metal light-shielding part (20) disposed above one surface of the substrate. The light sensor includes a calculation unit (40) that inputs 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 a part of the first light receiving surface is directly irradiated with light that passes through the opening portion of one surface and is not reflected by the reflecting surface (22) on one surface side of the light shielding portion. Directly incident on the first light-receiving surface through the opening and reflected by one or both of the one surface and the reflecting surface and indirectly provided on the substrate so as to be positioned in the first region (16). The first detection signal corresponding to the first intensity of the light including the indirect light incident on 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 on one surface, and the second light receiving element is provided in accordance with the second intensity of the indirect light. 2 The detection signal is output.

  The calculation unit receives the first detection signal and the second detection signal, and calculates a difference between the first intensity and the second intensity to remove an indirect light component included in the first intensity.

  According to this, 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 can acquire only indirect light components that do not contain direct light components. . 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.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is the 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 a calculating 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 the figure which showed the structure of the light sensor which concerns on 2nd Embodiment of this invention. It is the 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 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 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 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 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.

  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 component 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 unit 20, on the opening 21 of the light shielding unit 20, and on the light shielding unit 20 and the opening 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. The substrate 10, the light shielding unit 20, and the insulating layer 30 are configured as one semiconductor chip.

  The arithmetic 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 arithmetic 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 excluding the first region 16 in the one surface 11 of the substrate 10. 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 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 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.

  Next, 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. When 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, a direct light component can be 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 such a configuration of the 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 components of PD3 to PD4 have a broad characteristic in which a 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 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 where the light does not reach directly in the substrate 10. 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, the one surface 11 of the substrate 10 may be configured such that a region excluding the light receiving surfaces 14 and 15 of the light receiving elements 12 and 13 is 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.

  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 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 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present invention. For example, the insulating layer 30 may not be formed on the light shielding unit 20.

  Further, 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. Of course, 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.

DESCRIPTION OF SYMBOLS 10 Board | substrate 11 One surface 12 1st light receiving element 13 2nd light receiving element 14 1st light receiving surface 15 2nd light receiving surface 20 Light-shielding part 21 Opening part 40 Calculation part

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 one 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 reflection 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.   2. 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.   4. The light sensor according to claim 1, wherein the one surface is configured such that a region excluding the first light receiving surface and the second light receiving surface is configured as a metal surface. 5.   5. The light sensor according to claim 1, wherein the first light receiving element is provided on the substrate such that the entire first light receiving surface is located in the first region. 6.

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