Light-emitting / light-receiving module

Abstract

This invention provides a light-emitting / receiving module that can obtain sufficient light even when there are limitations on the amount of current. [Solution] This light-receiving and light-emitting module is a module in which a light-emitting unit and a light-receiving unit are mounted on a substrate, wherein the light-emitting unit irradiates a first emitted light in a first direction perpendicular to the surface of the substrate and irradiates a second emitted light in a direction intersecting the first direction, and the light-receiving unit has a reflective surface on its side surface that is inclined with respect to the surface of the substrate so as to reflect the second emitted light and irradiate it in substantially the same direction as the first emitted light.

Description

Technical Field

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[0001] The present invention relates to a light-emitting and light-receiving element module in which a light-emitting part and a light-receiving part are mounted on the same substrate.

Background Art

[0002] In a light-emitting and light-receiving element module, a light-emitting part (such as an LED) and a light-receiving part (such as an encoder module) are mounted on a substrate, light emitted from the light-emitting part is reflected by an irradiated object, and the reflected light is received by the light-receiving part (see, for example, Patent Document 1). The light-emitting and light-receiving element module can mount the light-emitting part and the light-receiving part in the same substrate, and can miniaturize the light-receiving and light-emitting part.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to increase the signal level of the received light signal in such a light-emitting and light-receiving element module, it is necessary to increase the current of the light-emitting part (such as an LED). However, since the heat generation of the light-emitting part increases as the current of the light-emitting part increases, there is a problem that a limit is imposed on the amount of current, particularly in a high-temperature environment, and it is difficult to obtain a sufficient amount of light from the light-emitting part.

[0005] In view of the above problems, an object of the present invention is to provide a light-emitting and light-receiving element module capable of obtaining a sufficient amount of light even when there is a limit on the amount of current of the light-emitting part.

Means for Solving the Problems

[0006] The present invention relates to a light-receiving and light-emitting module, wherein a light-emitting unit and a light-receiving unit are mounted on a substrate, and the light-emitting unit irradiates a first emitted light in a first direction perpendicular to the surface of the substrate and irradiates a second emitted light in a direction intersecting the first direction, and the light-receiving unit is provided with a reflective surface on its side surface that is inclined with respect to the surface of the substrate so as to reflect the second emitted light and irradiate it in substantially the same direction as the first emitted light.

[0007] According to this invention, not only the first emitted light emitted from the light-emitting unit in the direction perpendicular to the substrate, but also the second emitted light emitted in the intersecting direction is reflected by the reflective surface. Both the first and second emitted light can be output from the light-emitting unit, and the emitted light can be effectively utilized.

[0008] In one embodiment of the present invention, the light-emitting portion and the light-receiving portion are mounted on the substrate spaced apart from each other, and the reflective surface can be formed on the outer peripheral side portion facing the light-emitting portion.

[0009] In another aspect of the present invention, the light-receiving portion is provided with a through-hole extending along the first direction, the light-emitting portion is mounted inside the through-hole, and the reflective surface is formed on the side surface of the through-hole. This aspect provides the same effects as the above aspect, and in addition, the light-receiving portion and the light-emitting portion can be formed more compactly on the substrate, thereby reducing mounting costs.

[0010] In yet another embodiment of the present invention, the light-receiving portion is provided with a notch in part of the side surface, the light-emitting portion is mounted in the notch, and the reflective surface is formed on the side surface of the notch. In this embodiment, in addition to obtaining the same effects as in the above embodiment, the light-receiving portion and the light-emitting portion can be formed more compactly on the substrate, thereby reducing mounting costs. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a light-emitting and receiving module that can obtain a sufficient amount of light even when there is a limit to the amount of current in the light-emitting part. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing the configuration of a rotary encoder 1 that includes a light-emitting / receiving module 10 according to the first embodiment. [Figure 2] This is a plan view of a light-receiving and light-emitting module 10 according to a first embodiment of the present invention. [Figure 3] This is a cross-sectional view taken along line A-A' in Figure 2. [Figure 4] This is a plan view of the light-emitting / receiving module 10 according to the second embodiment. [Figure 5] This is a cross-sectional view taken along line A-A' in Figure 4. [Figure 6] This is a plan view of the light-receiving and light-emitting module 10 of the third embodiment. [Modes for carrying out the invention]

[0013] This embodiment will be described below with reference to the attached drawings. In the attached drawings, functionally identical elements may be indicated by the same number. The attached drawings show embodiments and implementation examples in accordance with the principles of this disclosure, but these are for the purpose of understanding this disclosure and are not to be used in any way to restrict the interpretation of this disclosure. The descriptions in this specification are merely typical examples and do not limit the claims or applications of this disclosure in any way. In each drawing, identical or substantially equivalent elements, members and parts are given the same reference numerals. Also, the dimensions and proportions in the drawings are exaggerated for illustrative purposes and may differ from actual proportions.

[0014] While this embodiment is described in sufficient detail for those skilled in the art to implement the disclosure, it is important to understand that other implementations and forms are possible, and that the configuration and structure can be modified and various elements replaced without departing from the scope and spirit of the technical idea of ​​this disclosure. Therefore, the following description should not be construed as limiting to this.

[0015] [First Embodiment] Figure 1 is a schematic diagram showing the configuration of a rotary encoder 1 including a light-receiving module 10 according to a first embodiment. This rotary encoder 1 comprises a rotary scale 5 and a light-receiving module 10.

[0016] The rotary scale 5 is mounted on a rotating body and has a pattern formed on its circumference for detecting the rotation angle. In the case of a three-phase type, the pattern includes an A-phase pattern, a B-phase pattern which is 90° out of phase with respect to the A-phase pattern, and a Z-phase pattern which is in the same phase as the A-phase or B-phase pattern. The light-receiving and light-emitting module 10 is configured to irradiate these patterns with light and to receive the reflected light from the irradiated light on the patterns. By analyzing the light-receiving signal from the light-receiving and light-emitting module 10 with an analysis unit (not shown), the amount of rotation and the direction of rotation of the rotary scale 5 can be detected.

[0017] The configuration of the light-emitting / receiving module 10 will be described in detail with reference to Figures 2 and 3. Figure 2 is a plan view of the light-emitting / receiving module 10, and Figure 3 is a cross-sectional view taken along line A-A' in Figure 2.

[0018] As shown in FIG. 2, the light-emitting and light-receiving element module 10 is configured by mounting a light-emitting unit 20 and a light-receiving unit 30 on a substrate SB. The light-emitting unit 20 and the light-receiving unit 30 are mounted on the substrate SB with a predetermined distance (for example, several millimeters) therebetween. The light-emitting unit 20 is, for example, an infrared LED, and emits light from a light-emitting window W in a direction substantially perpendicular to the surface of the substrate SB (the direction perpendicular to the plane of FIG. 2). However, the light-emitting unit 20 irradiates not only the light traveling in a direction substantially perpendicular to the surface of the substrate SB from the light-emitting window W, but also leakage light traveling in a direction intersecting the vertical direction (for example, the horizontal direction). The light-receiving unit 30 includes a reflecting surface P1 for reflecting this leakage light. Details will be described later.

[0019] As shown in FIG. 3, as an example, the LED is formed by laminating an N-type contact layer 21, an N-type cladding layer 22, a light-emitting layer 23, a P-type cladding layer 24, a P-type contact layer 25, and a high-resistance layer 26. The light-emitting unit 20 and the light-receiving unit 3 are connected by a contact unit 40 and bonding wires 50.

[0020] The N-type contact layer 21 can be formed, for example, by doping gallium arsenide (GaAs) with an n-type impurity (such as Se). A cathode electrode EL is connected to the back surface of the N-type contact layer 21. The N-type cladding layer 22 can be formed, for example, by doping aluminum gallium arsenide (AlGaAs) with an n-type impurity (Se, Si, etc.). The light-emitting layer 23 is a portion that emits light when electrons and holes injected from the P-type layer and the N-type layer recombine, and can be formed of, for example, AlGaAs.

[0021] The P-type cladding layer 24 can be formed, for example, by doping AlGaAs with a p-type impurity (for example, Zn, Mg, C). A p-type contact layer 25 is further formed on the upper layer of the P-type cladding layer 24, and an anode electrode (not shown) is connected to this P-type contact layer 25. The P-type contact layer 25 can be formed, for example, by doping AlGaAs with a P-type impurity. The high-resistance layer 26 has a function of restricting the region where carriers flow and defining the light-emitting window W.

[0022] As shown in Figure 3, the light-receiving unit 30 comprises a silicon substrate 31, for example, made of silicon, and an interlayer insulating film 32 formed on the surface of the silicon substrate 31, on the substrate SB. The aforementioned photodiode array 33 is formed on this interlayer insulating film 32. The aforementioned reflective surface P1 is formed on the side of the silicon substrate 31 facing the light-emitting unit 20. The reflective surface P1 is configured to reflect, for example, leaked light leaking horizontally from the light-emitting layer 23. The reflective surface P1 is a reflective surface that is inclined at an angle with respect to the surface of the substrate SB. However, the angle of inclination is arbitrary, and it is sufficient that the angle is such that the leaked light is reflected in approximately the same direction as the light emitted from the light-emitting window P1. The reflected light reflected by the reflective surface P1 is irradiated in the direction of scale 5 together with the light emitted from the light-emitting window W by a focusing optical system (not shown). The reflective surface formed on the silicon substrate 31 can be formed by anisotropic etching of silicon using a strong alkaline solution, as an example. For example, by cutting out the (111) plane of silicon, it becomes possible to form reflective surfaces as shown in Figures 3 and 5.

[0023] In this way, the light-receiving and light-emitting module 10 of the first embodiment can reflect the light leaking from the light-emitting section 20 off the reflective surface P1 formed on the side surface of the adjacent light-receiving section 30 and merge it with the light emitted from the light-emitting window W. Therefore, even in environments where the amount of current is limited, the leaked light can be effectively utilized to obtain a sufficient amount of light.

[0024] [Second Embodiment] Next, the light-emitting / receiving module 10 according to the second embodiment will be described with reference to Figures 4 and 5. In Figures 4 and 5, components identical to those in the first embodiment are denoted by the same reference numerals as in Figures 2 and 3, and redundant explanations are omitted.

[0025] Figure 4 is a plan view of the light-receiving and light-emitting module 10 of the second embodiment, and Figure 5 is a cross-sectional view taken along line A-A' in Figure 4. This light-receiving and light-emitting module 10 differs from the first embodiment in that a through-hole PH is provided in the center of the light-receiving section 30, for example, penetrating the interlayer insulating film 32 and the silicon substrate 31, and a light-emitting section 20 is provided inside the through-hole PH. The side surface of the through-hole PH is a reflective surface P1 that is inclined with respect to the surface of the substrate SB, similar to the first embodiment (see Figure 5).

[0026] According to this second embodiment, the reflective surface P1 is formed as a closed curved surface surrounding the light-emitting section 20. Since more of the leaked light from the light-emitting section 20 can be used as emitted light, a light-receiving and light-emitting module with higher energy efficiency can be obtained compared to the first embodiment.

[0027] [Third Embodiment] A light-emitting / receiving module 10 according to the third embodiment will be described with reference to Figure 6. In Figure 6, components identical to those in the first embodiment are denoted by the same reference numerals as in Figure 2, and redundant explanations are omitted.

[0028] Figure 6 is a plan view of the light-receiving and light-emitting module 10 of the third embodiment. This light-receiving and light-emitting module 10 differs from the first embodiment in that a notch is provided in a part of the side surface of the light-receiving section 30, for example, by cutting out the interlayer insulating film 32 and the silicon substrate 31, and a light-emitting section 20 is provided inside the notch. The side surface of the notch is a reflective surface P1 that is inclined with respect to the surface of the substrate SB, similar to the first embodiment. According to this third embodiment, the reflective surface P1 is formed as a curved surface that surrounds the light-emitting section 20 from three directions. Since more of the leaked light from the light-emitting section 20 can be used as emitted light, a light-receiving and light-emitting module with higher energy efficiency can be obtained compared to the first embodiment.

[0029] This disclosure is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail for the purpose of explaining this disclosure clearly, and are not necessarily limited to having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of Symbols]

[0030] 1…Rotary encoder 5…Rotary scale 10…Light-emitting / receiving module 20...Light-emitting part 21…N-type contact layer 22...N-type cladding layer 23…Luminous layer 24...P-type cladding layer 25…P-type contact layer 26…High resistance layer 30...Light receiving section 31…Silicon substrate 32...Interlayer insulating film 33…Photodiode array 40... Contact section 50…Bonding wire W...light-emitting window EL… Circuit board electrode wiring P1…Reflective surface PH…Through hole SB... Circuit board

Claims

1. A light-emitting and light-receiving module in which a light-emitting unit and a light-receiving unit are mounted on a substrate, The light-emitting unit irradiates a first emitted light in a first direction perpendicular to the surface of the substrate, and irradiates a second emitted light in a direction intersecting the first direction. The light-receiving unit is provided with a reflective surface on its side that is inclined with respect to the surface of the substrate so as to reflect the second emitted light and irradiate it in substantially the same direction as the first emitted light. A light-emitting and receiving module characterized by the following features.

2. The light-emitting unit and the light-receiving unit are mounted on the substrate spaced apart from each other. The light-receiving and light-emitting module according to claim 1, wherein the reflective surface is formed on the outer peripheral side portion facing the light-emitting portion.

3. The light-receiving section is provided with a through hole that penetrates along the first direction, The light-emitting part is mounted inside the through-hole, The light-receiving and light-emitting module according to claim 1, wherein the reflective surface is formed on the side surface of the through hole.

4. The light-receiving section is provided with a notch in a part of the side surface, The light-emitting part is mounted in the notched portion, The light-receiving and light-emitting module according to claim 1, wherein the reflective surface is formed on the side surface of the notch.

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