JP2019153683A - Optical waveguide type photosensor - Google Patents

Abstract

To provide a photosensor capable of easily making a translucent part for proximity detection extremely small, without causing a problem of crosstalk where the light emitted from a light-emitting device is received directly by a photodetector.SOLUTION: An optical guide 5 of a photosensor 1 is formed of an emission core part 5a constituting an emission light guide part, an incident core part 5b constituting an incident light guide part, and a clad part 5c constituting a light guide part enclosure part. The emission core part 5a guides the light emitted from a surface emitting laser 3 to be emitted from a light emission end face 5a1 to the outer space, and the incident core part 5b receives the light incident from the outer space by a light introduction end face 5b1 before being introduced to a PD4. The clad part 5c covers around the emission core part 5a and the incident core part 5b and confines the light therein. The emission core part 5a is bent so that the light emission end side overlaps the light introduction end side, and the light emission end face 5a1 is formed in the light introduction end face 5b1.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical sensor that includes a light emitting element and a light receiving element arranged side by side, and detects a detection target by receiving light reflected from the light emitting element by the light receiving element.

  Among the optical sensors, those that detect proximity or illuminance are configured by arranging a light emitting diode (LED) 201 and a photodiode (PD) 202 side by side, as shown in the sectional view of FIG. . Recently, some ICs (Highly Integrated Circuits) are built with PDs. In the proximity detection, when a reflection object exists above the optical sensor, the light emitted from the LED 201 is reflected by the reflection object, and the reflected light is detected by the PD 202. Based on the amount of reflected light, it is determined whether or not the detection target is approaching the optical sensor, whether or not there is a detection target, and the like. In the illuminance detection, the LED 201 is not illuminated, and ambient light is detected by the PD 202, whereby the illuminance is measured. Generally, near-infrared wavelengths are used for proximity detection, and light having a wavelength in the visible light region is used for illuminance detection.

  Recently, this proximity detection is also used for smart phones. As shown in the partial plan view of FIG. 1B, the smart phone 203 is provided with a proximity detection light transmitting portion 205 above the display portion 204. The above-described optical sensor is built in the device below the proximity detecting translucent portion 205. When making a call, an ear is applied to the vicinity of the proximity detection translucent part 205, but the light emitted from the LED 201 is reflected by the ear, and the reflected light is detected by the PD 202. It is detected by an optical sensor that an ear has been applied to the periphery of the unit 205. Since the display unit 204 is not seen when making a call, the smart phone 203 turns off the backlight of the display unit 204 to save power.

  Conventionally, as a device that uses an optical sensor for proximity detection, for example, there is a foldable wireless telephone disclosed in Patent Document 1.

  The foldable wireless telephone 100 is shown in cross section in FIG. 2, and detects whether or not the cover 104 of the wireless telephone 100 is opened from the base 102 by an optical sensor. A photoemitter 116 ′ in the base 102 emits light from the opening 604. When the cover portion 104 is closed as shown, the light 608 from the photoemitter 116 'is reflected by the reflection surface 606 of the cover portion 104, and the reflected light is detected by the photodetector 118'. The light from the photoemitter 116 ′ is prevented from reaching the photodetector 118 ′ directly by the opaque barrier 602. When the cover 104 is opened, only a small amount of light reaches the photo detector 118 '. Therefore, whether or not the cover 104 is opened is detected based on the magnitude of the light detected by the photo detector 118 '.

JP 2006-94485 A

  In the conventional smart phone 203, light enters and exits the optical sensor via the proximity detection translucent part 205. However, in order to make the proximity detection translucent part 205 inconspicuous, the body of the smart phone 203 is usually red or It is provided in black. As a recent trend, the design of the smart phone 203 has made it an important issue how to make the proximity detection light transmitting portion 205 smaller in order to make the proximity detection light transmission portion 205 more inconspicuous. However, if the proximity detecting translucent part 205 is made smaller, the distance between the LED 201 and the PD 202 becomes closer, and the problem of crosstalk in which the light emitted from the LED 201 is directly received by the PD 202 is greatly highlighted. In order to avoid this problem of crosstalk, a barrier that shields light from each other is required between the LED 201 and the PD 202 as in the optical sensor disclosed in Patent Document 1, but the size of each component is reduced. However, it is difficult to make the proximity detection translucent part 205 extremely small.

The present invention has been made to solve such problems,
In the optical sensor that is configured by arranging the light emitting element and the light receiving element side by side, and receives the light emitted from the light emitting element and reflected by the light receiving element, and detects the detection target,
The light emitting element is composed of a surface emitting laser,
Each of the outgoing light guide unit that guides the light emitted from the surface emitting laser and emits it to the external space, the incident light guide unit that guides the light incident from the external space to the light receiving element, and each of the outgoing light guide unit and the incident light guide unit A light guide portion surrounding portion that surrounds the light guided by the outgoing light guide portion and the incident light guide portion to confine the light guided by the outgoing light guide portion and the incident light guide portion, and the light guided by the outgoing light guide portion to the external space The light emitting end face to be emitted includes an optical waveguide formed in the plane of the light introducing end face of the incident light guiding portion that receives light incident from the external space.

  According to this configuration, the light propagating through the outgoing light guide and the incoming light guide is confined inside each of the outgoing light guide and the incoming light guide by the light guide enclosure formed around them. Since the outgoing light guide unit, the incoming light guide unit, and the light guide surrounding portion are formed as optical waveguides, miniaturization is easy, and the outgoing light guide unit and the incoming light guide unit can be freely bent and easily desired. It can be formed in the shape of Accordingly, the light emission end face that bends the outgoing light guide part so that the light emission end side of the outgoing light guide part overlaps the light introduction end side of the incident light guide part, and emits the light guided by the outgoing light guide part to the external space, By forming in the plane of the light introduction end face of the incident light guide section that receives light incident from the space, the proximity detecting translucent section is reduced to a size that allows only the light introduction end face of the incident light guide section to face. be able to. Therefore, it is possible to provide an optical sensor that can easily make the proximity detecting light transmitting portion extremely small without causing a problem of crosstalk in which light emitted from the light emitting element is directly received by the light receiving element.

  Further, according to the present invention, the optical waveguide is formed of a transparent resin, the light refractive index of the outgoing light guide unit and the incident light guide unit is larger than the light refractive index of the light guide unit surrounding part, and the light refractive index of the outgoing light guide unit is Is formed larger than the light refractive index of the incident light guide.

  According to this configuration, the light that is surrounded by the light guide enclosure and propagates through the output light guide and the incident light guide is the light refractive index of the output light guide, the incident light guide, and the light guide enclosure. Due to the difference, the light is confined in each of the outgoing light guide and the incident light guide. Further, light propagating through the outgoing light guide unit surrounded by the incoming light guide unit is confined inside the outgoing light guide unit due to a difference in refractive index between the outgoing light guide unit and the incident light guide unit.

  Further, according to the present invention, the outgoing light guide unit and the incident light guide unit are formed of a transparent resin, the light refractive index of the outgoing light guide unit is larger than the light refractive index of the incident light guide unit, and the light guide unit surrounding unit shields light. It is formed from resin.

  According to this configuration, light propagating through the outgoing light guide unit and the incident light guide unit surrounded by the light guide unit enclosure unit is shielded by the light guide unit enclosure unit, and each of the outgoing light guide unit and the incident light guide unit is provided. Confined inside. Further, light propagating through the outgoing light guide unit surrounded by the incoming light guide unit is confined inside the outgoing light guide unit due to a difference in refractive index between the outgoing light guide unit and the incident light guide unit.

  Further, the present invention is characterized in that the outgoing light emitted from the light emission end face of the outgoing light guide section is set in a direction having a predetermined angle with respect to the light introduction end face of the incident light guide section.

  According to this configuration, the outgoing light is emitted from the light emission end face of the outgoing light guide section with a predetermined angle with respect to the light introduction end face of the incident light guide section. For this reason, by setting the emission direction of the emitted light with respect to the light introduction end face to a predetermined angle, the proximity detection translucent part is emitted from the light emission end face within the light introduction end face and provided in front of the optical sensor. In this case, it is possible to suppress the light reflected on the optical sensor side from entering the light introduction end face as stray light.

  According to the present invention, the proximity detecting translucent portion provided in the smart phone or the like can be easily made extremely small without causing the problem of crosstalk in which light emitted from the light emitting element is directly received by the light receiving element. An optical sensor can be provided.

(A) is sectional drawing for demonstrating the concept of the conventional optical sensor, (b) is a fragmentary top view of a smart phone. It is sectional drawing of the conventional optical sensor disclosed by patent document 1. FIG. (A) is sectional drawing of the optical waveguide type optical sensor by one Embodiment of this invention, (b) is a top view. It is sectional drawing which shows the relative relationship of the optical waveguide type optical sensor by one Embodiment, and the glass plate of a smart phone. (A) is a plan view when a glass plate of a smart phone is disposed in front of an optical waveguide optical sensor according to one embodiment, (b) is formed in a straight line without bending the emission core portion, It is a top view when the glass plate of a smart phone is arrange | positioned ahead of the optical waveguide type optical sensor in which the light emission end surface was formed in front of the surface emitting laser.

  Next, the form for implementing the optical waveguide type optical sensor of this invention is demonstrated.

  FIG. 3A is a cross-sectional view of the optical waveguide type optical sensor 1 according to one embodiment of the present invention, and FIG. 3B is a plan view thereof.

  The optical sensor 1 is configured by arranging a surface emitting laser 3 as a light emitting element and a PD 4 as a light receiving element side by side on a printed board 2. The surface emitting laser 3 of this embodiment is composed of a vertical cavity surface emitting laser (VCSEL). In general, a semiconductor laser resonates light in a direction parallel to the substrate surface and emits light in a direction parallel to the substrate surface. The surface emitting laser 3 of the present embodiment configured by a VCSEL is The light is resonated in a direction perpendicular to the substrate, and the light is emitted in a direction perpendicular to the substrate surface. The optical sensor 1 receives the light emitted from the surface emitting laser 3 and reflected by the PD 4, and detects the detection target. In the present embodiment, it is assumed that the detection target exists in front of the PD 4.

  The optical sensor 1 includes an optical waveguide 5. The optical waveguide 5 is formed of an output core portion 5a constituting an outgoing light guide portion, an incident core portion 5b constituting an incident light guide portion, and a clad portion 5c constituting a light guide surrounding portion. The emission core portion 5a guides the light emitted from the surface emitting laser 3 to be emitted to the external space, and the incident core portion 5b guides the light incident from the external space to the PD 4. The clad part 5c covers the periphery of the output core part 5a and the incident core part 5b, and confines the light guided by the output core part 5a and the incident core part 5b in the output core part 5a and the incident core part 5b.

  The emission diameter of the surface emitting laser 3 is generally about 5 to 20 μm in diameter φ and is quite thin. A light emitting point of the surface emitting laser 3 is connected to an emission core portion 5a having a thin diameter corresponding to the light emission diameter. In addition, a thick incident core portion 5b corresponding to the size is connected to the light receiving area of the PD4. The incident core portion 5b is formed to have a larger diameter as it approaches the light introduction end face 5b1 that receives light incident from the external space, and the diameter of the light introduction end face 5b1 is set to a diameter of about several hundred μm. Is widely secured. Since the exit core portion 5a is quite thin as described above, the shape has a large degree of freedom in bending, and is bent so that the light emission end side overlaps the light introduction end side of the entrance core portion 5b. A light emission end face 5a1 for emitting light guided by the emission core part 5a to the external space is formed in the plane of the light introduction end face 5b1 of the incident core part 5b.

  The optical waveguide 5 is formed of a transparent resin, and the light refractive index N1 of the output core portion 5a and the light refractive index N2 of the incident core portion 5b are formed larger than the light refractive index N3 of the clad portion 5c. The refractive index N1 is formed larger than the light refractive index N2 of the incident light guide (N1> N2> N3). Such an optical waveguide 5 uses a mold, transfers the shape of the core layer to the cladding layer with the mold, and injects the core material into the transferred groove to form an optical circuit, a coating method using a dispenser, etc. It is formed by the manufacturing method.

  As a manufacturing method of the optical sensor 1, apart from the step of forming the surface emitting laser 3 and the PD 4 on the printed circuit board 2, the optical waveguide 5 is separately formed by a replication method or the like using a mold or the like. There is a method in which the optical sensor 5 is manufactured by placing the optical waveguide 5 on the surface emitting laser 3 and the PD 4 formed on the printed circuit board 2. Further, a clad resin constituting the clad portion 5c is applied by a dispenser on the surface emitting laser 3 and the PD 4 formed on the printed circuit board 2 by a coating method, and each of the outgoing core portion 5a and the incident core portion 5b is constituted The core resin is discharged from the needle of the dispenser into the clad resin while drawing the respective shapes, whereby the output core portion 5a and the incident core portion 5b are formed in the clad portion 5c, and the optical sensor 1 is manufactured. There is also a method.

  FIG. 4 is a cross-sectional view showing a relative relationship between the optical sensor 1 and the glass plate 206 constituting the body of the smart phone 203 (see FIG. 1B) disposed in front of the optical sensor 1. 4 that are the same as or correspond to those in FIG. 3 are assigned the same reference numerals, and descriptions thereof are omitted. A proximity detection translucent portion 207 that transmits light is formed in the front area of the PD 4 on the glass plate 206, and the other glass areas are colored so as not to transmit light.

  In the optical sensor 1 of the present embodiment, the outgoing light A emitted from the light emitting end face 5a1 of the outgoing core portion 5a is set in a direction having a predetermined angle with respect to the light introducing end face 5b1 of the incoming core portion 5b. . The direction of the outgoing light A is set by the relative refractive index difference (= (N1−N2) / N1) between the optical refractive index N1 of the incident core portion 5b and the optical refractive index N2 of the outgoing core portion 5a, that is, the numerical aperture. This can be done by adjusting (NA). The emitted light A hits the detection target, becomes reflected light B, passes through the proximity detecting light transmitting portion 207, and is received by the light introduction end face 5b1.

  The exit core portion 5a and the incident core portion 5b are graded indexes (GI) having a gradient from the center of the core toward the periphery, even if the optical refractive indexes N1 and N2 are step index (SI) types in the core. Either type or both. When there is a concern about optical loss at the interface between the core portions 5a, 5b and the cladding portion 5c, it is preferable to form a graded index (GI) type.

  According to such an optical waveguide type optical sensor 1 of the present embodiment, the light that is surrounded by the clad portion 5c and propagates through the output core portion 5a and the incident core portion 5b is transmitted by the clad portion 5c formed around them. It is confined in each of the output core part 5a and the incident core part 5b. This confinement of light in the present embodiment is performed by the difference in optical refractive index between the output core portion 5a and the incident core portion 5b and the clad portion 5c. In addition, the light that is surrounded by the incident core portion 5b and propagates through the output core portion 5a is confined inside the output core portion 5a due to the difference in the refractive index between the output core portion 5a and the incident core portion 5b. Therefore, the light emitted from the surface emitting laser 3 is emitted from the light emission end face 5a1 without leaking from the emission core part 5a on the way. Further, the light incident on the light introduction end face 5b1 of the incident core portion 5b is received by the PD 4 without leaking from the incident core portion 5b on the way.

  Such an optical sensor 1 is easy to miniaturize because the output core portion 5a, the incident core portion 5b, and the clad portion 5c are formed as the optical waveguide 5, and the output core portion 5a and the incident core portion 5b are It can be freely bent and easily formed into a desired shape. Therefore, as shown in the drawing, the light that causes the light emission end side of the emission core portion 5a to overlap the light introduction end side of the incidence core portion 5b is bent so that the light guided by the emission core portion 5a is emitted to the external space. The emission end face 5a1 can be formed in the plane of the light introduction end face 5b1 of the incident core portion 5b that receives light incident from the external space. Therefore, as shown in FIG. 5A, the proximity detecting light transmitting portion 207 of the smart phone 203 can be reduced to a size that allows only the light introduction end face 5b1 of the incident core portion 5b to face. Therefore, it is possible to provide an optical sensor 1 that can easily make the proximity detecting light transmitting portion 207 extremely small without causing a problem of crosstalk in which light emitted from the surface emitting laser 3 is directly received by the PD 4. Can do.

  FIG. 5A is a plan view when the glass plate 206 constituting the body of the smart phone 203 is disposed in front of the optical sensor 1. 5 that are the same as or correspond to those in FIG. 3 and FIG. According to the present embodiment, considering only the PD 4 side, as described above, the small proximity detecting translucent portion 207 that faces only the light introduction end face 5b1 of the incident core portion 5b is formed on the glass plate 206. The optical sensor 1 can be functioned. In FIG. 6B, the emission core portion 5a is formed in a straight line without being bent as in the present embodiment, and in front of the optical sensor 1a in which the light emitting end surface 5a2 is formed in front of the surface emitting laser 3. It is a top view at the time of the glass plate 206 which comprises the body of the smart phone 203 being arrange | positioned. In this case, the proximity detecting light transmitting portion 208 formed on the glass plate 206 must consider the surface emitting laser 3 side in addition to the PD 4 side, and has a large size surrounding the light introducing end surface 5b1 and the light emitting end surface 5a2. It becomes an area. That is, according to the optical waveguide type optical sensor 1 of the present embodiment, the proximity detection provided in the smart phone 203 or the like without causing the problem of crosstalk in which the light emitted from the surface emitting laser 3 is directly received by the PD 4. It is possible to provide the optical sensor 1 in which the light transmitting portion 207 can be easily made extremely small.

  In addition, according to the optical waveguide type optical sensor 1 of the present embodiment, as shown in FIG. 4, the light emitting end face of the output core part 5a has a predetermined angle with respect to the light introduction end face 5b1 of the incident core part 5b. Outgoing light A is emitted from 5a1. Therefore, by setting the emission direction of the emitted light A with respect to the light introduction end face 5b1 to a predetermined angle, the light is emitted from the light emission end face 5a1 in the plane of the light introduction end face 5b1 and is provided in front of the optical sensor 1. It is possible to prevent the light a that hits the detection light transmitting portion 207 and reflects to the optical sensor side from entering the light introduction end face 5b1 as stray light.

  In the above embodiment, the optical waveguide 5 is formed of a transparent resin, and the light propagating through the output core portion 5a and the incident core portion 5b is the light from the output core portion 5a, the incident core portion 5b, and the cladding portion 5c. The case where it is confined inside each of the output core portion 5a and the incident core portion 5b due to the difference in refractive index has been described. However, the output core portion 5a and the incident core portion 5b are formed from a transparent resin, the light refractive index N1 of the output light guide portion is made larger than the light refractive index N2 of the incident light guide portion, and the cladding portion 5c is formed from a light shielding resin. You may comprise. According to this configuration, the light propagating through the exit core portion 5a and the entrance core portion 5b is shielded by the cladding portion 5c surrounding the exit core portion 5a and the entrance core portion 5b, and each of the exit core portion 5a and the entrance core portion 5b. Confined inside. In addition, the light that is surrounded by the incident core portion 5b and propagates through the output core portion 5a is confined inside the output core portion 5a due to the difference in the refractive index between the output core portion 5a and the incident core portion 5b. Even with such a configuration, the same effects as the above-described embodiment can be obtained.

  Moreover, in said embodiment, when the emitted light A radiate | emitted from the light emission end surface 5a1 of the output core part 5a is set to the direction which has a predetermined angle with respect to the light introduction end surface 5b1 of the incident core part 5b Explained. However, when stray light is not a problem, the emitted light A does not necessarily have a predetermined angle, and may be configured to be emitted perpendicular to the light introduction end face 5b1. Further, the light emission end face 5a1 does not need to be positioned at the center of the light introduction end face 5b1, but may be within the plane of the light introduction end face 5b1.

  In the above embodiment, the optical waveguide type optical sensor 1 is used to reduce the proximity detecting light transmitting portion 205 of the smart phone 203, but the application is not limited to this. For example, it can also be used to reduce the proximity detecting light transmitting portion in other electronic devices such as mobile phones. Further, by not emitting the surface emitting laser 3, the optical waveguide optical sensor 1 can be used for illuminance detection.

DESCRIPTION OF SYMBOLS 1 ... Optical waveguide type optical sensor 2 ... Printed circuit board 3 ... Surface emitting laser (light emitting element)
4 ... PD (photodiode: light receiving element)
5a: Output core part (output light guide part)
5a1 ... light emission end face 5b ... incident core part (incident light guide part)
5b1 ... light introduction end face 5c ... cladding part (light guide part surrounding part)
206 ... Glass plate 207 ... Transmission part for proximity detection

Claims (4)

In the optical sensor that is configured by arranging the light emitting element and the light receiving element side by side, and that receives the light emitted from the light emitting element and reflected by the light receiving element and detects the detection target,
The light emitting element is composed of a surface emitting laser,
An outgoing light guide that guides the light emitted from the surface emitting laser and emits it to the external space, an incident light guide that guides light incident from the external space to the light receiving element, the outgoing light guide, and the incident light A light guide portion surrounding portion that covers each periphery of the light portion and that guides the light guided by the output light guide portion and the incident light guide portion to the output light guide portion and the incident light guide portion, and the output light The light emission end face that emits light guided by the light section to the external space includes an optical waveguide formed in the plane of the light introduction end face of the incident light guide section that receives light incident from the external space. Optical waveguide type optical sensor.   The optical waveguide is formed of a transparent resin, and each light refractive index of the outgoing light guide portion and the incident light guide portion is larger than a light refractive index of the light guide portion surrounding portion, and the light refractive index of the outgoing light guide portion. The optical waveguide type optical sensor according to claim 1, wherein the optical waveguide type optical sensor is formed to be larger than a light refractive index of the incident light guide portion.   The outgoing light guide part and the incident light guide part are made of a transparent resin, the light refractive index of the outgoing light guide part is larger than the light refractive index of the incident light guide part, and the light guide surrounding part is a light shielding resin. The optical waveguide type optical sensor according to claim 1, wherein the optical waveguide type optical sensor is formed of:   The outgoing light emitted from the light emission end face of the outgoing light guide part is set in a direction having a predetermined angle with respect to the light introduction end face of the incident light guide part. 4. The optical waveguide optical sensor according to any one of 3 above.

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