TWI770742B - Light sensor - Google Patents

Abstract

A light sensor including a substrate, a light source module, a sensing chip, and a transparent package is provided. The light source module, the sensor chip and the transparent package are disposed on a surface of the substrate, wherein the transparent package covers the sensor chip. There is a distance between the transparent package and the light source module. One side of the transparent package, which is closest to the light source module, has a first slope and a second slope connected to the first slope. The first slope has a first slope angle and the second slope have a second slope angle. The second slope angle is greater than the first slope angle. Based on the two-segment slope structure of the transparent package, light from the light source module into the transparent package can be reduced, thus reducing an ACT of the sensing chip.

Description

light sensor

The present invention relates to a light sensor, and more particularly, to a light sensor with reduced noise floor.

FIG. 1 shows a cross-sectional view of a conventional light sensor 10. The light sensor 10 may be, for example, a proximity sensor for detecting the proximity of an object. The light sensor 10 includes a substrate 12 , a light source module 14 , a blocking wall 16 and a sensing module 18 . The light source module 14 includes a light-emitting element 142 and a light-transmitting package 144 , wherein the light-transmitting package 144 covers the light-emitting element 142 . The light emitting element 142 may be a vertical cavity surface emitting laser (Vertical-Cavity Surface-Emitting Laser; VCSEL) or a light emitting diode (Light-Emitting Diode; LED), and the light emitting element 142 is disposed on the substrate 12 . The sensing module 18 includes a sensing chip 182 , a plurality of bonding wires 184 , and a transparent package 186 , wherein the transparent package 186 covers the sensing chip 182 and the bonding wires 184 . The sensing chip 182 is used for sensing light. A plurality of bonding wires 184 are connected to the sensing chip 182 and the substrate 12 . The circuits on the sensing chip 182 and the substrate 12 can transmit signals through a plurality of bonding wires 184 . In an ideal state, the light emitted by the light emitting element 142 will only be emitted upward from the transparent package body 144 , as shown by the light L1 in FIG. 1 . However, part of the light L2 emitted by the light emitting element 142 may still be emitted from the side of the transparent package 144 , and the light L2 emitted from the side of the transparent package 144 is called internal leakage light. If the internal leakage light enters the transparent package body 186 , the noise floor (Air Cross-Talk; ACT) will be formed, which affects the accuracy of the sensing chip 182 . Therefore, an opaque blocking wall 16 is disposed between the light source module 14 and the sensing module 18 to prevent internal light leakage from entering the sensing module 18 to reduce the noise floor.

However, to increase the retaining wall 16 requires additional process steps, which not only increases the complexity of the process, but also increases the process time. In addition, the stress of the retaining wall 16 may also cause damage to the transparent packages 144 and 186, thereby reducing the yield.

One of the objectives of the present invention is to provide a photo sensor with reduced process complexity.

One of the objectives of the present invention is to provide a light sensor with a reduced noise floor.

According to the present invention, a light sensor includes a substrate, a light source module, a sensing chip, and a light-transmitting package. The substrate has a surface. The light source module is arranged on the surface to provide a first light. The sensing chip is disposed on the surface for sensing the second light entering the light sensor. The transparent package body is disposed on the surface and covers the sensing chip, and there is a gap between the transparent package body and the light source module. One side of the transparent package body close to the light source module has a first inclined surface and a second inclined surface connected with the first inclined surface. There is a turning point between the first slope and the second slope, the first slope is between the substrate and the turning point, and the second slope is between the turning point and the top of the transparent package. There is a first inclination angle between the first inclined plane and the normal line perpendicular to the surface, and a second inclination angle between the second inclined plane and the normal line. The first inclination angle and the second inclination angle are positive values, and the second inclination angle is greater than the first inclination angle.

The photo sensor of the present invention does not need a blocking wall, so the complexity of the process can be reduced and the yield of the process can be improved. The light-transmitting package body has a two-segment inclined surface structure close to the light source module to reduce internal light leakage entering the light-transmitting package body, thereby reducing the noise floor of the sensing chip.

10: Light sensor

12: Substrate

14: Light source module

142: Light-emitting element

144: light-transmitting package

16: Retaining Wall

18: Sensing module

182: Sensing chip

184: Wire

186: transparent package

20: Light sensor

22: Substrate

222: Surface

24: Light source module

242: Light-emitting element

244: light-transmitting package

26: Sensing module

262: Sensing chip

264: Wire

266: transparent package

2662: First Bevel

2664: Second Bevel

2666: Turning Point

28: Normal

30: Energy Distribution

302: Location

G1: Gap

H1: Distance

L1: light

L2: light

L3: Light

θ1: first tilt angle

θ2: Second tilt angle

FIG. 1 shows a cross-sectional view of a conventional photosensor.

FIG. 2 shows a cross-sectional view of the photo sensor of the present invention.

FIG. 3 illustrates how FIG. 2 prevents internal light leakage from affecting the sensing chip.

FIG. 2 shows a cross-sectional view of the photo sensor 20 of the present invention. The light sensor 20 of the present invention can be used as a proximity sensor (Proximity Sensor; PS) and an ambient light sensor (Ambient Light Sensor; ALS), but the present invention is not limited thereto. The light sensor 20 of FIG. 2 includes a substrate 22 , a light source module 24 and a sensing module 26 , wherein the light source module 24 and the sensing module 26 are disposed on the surface 222 of the substrate 22 . The light source module 24 includes a light emitting element 242 and a transparent package 244 . The light emitting element 242 is disposed on the surface 222 for providing the light L1. The light emitting elements 242 may be, but are not limited to, VCSELs or LEDs. The light-transmitting package 244 is disposed on the surface 222 and covers the light-emitting element 242 . The sensing module 26 is disposed in the X direction of the light source module 24 . The sensing module 26 includes a sensing chip 262 , at least one bonding wire 264 and a transparent package body 266 . The sensing chip 262 is disposed on the surface 222 for sensing the light L3. In one embodiment, the light L3 may be the reflected light of the light L1 or ambient light around the light sensor 20 . A plurality of bonding wires 264 are connected to the sensing chip 262 and the substrate 22 . The circuits on the sensing chip 262 and the substrate 22 can transmit signals through a plurality of bonding wires 264 . The transparent package body 266 is disposed on the surface 222 and covers the sensing chip 262 and the plurality of bonding wires 264 . There is a distance G1 between the transparent package body 266 and the light source module 24 . In one embodiment, the distance G1 is 0.3 mm˜0.5 mm, but the present invention is not limited thereto. The transparent package body 266 has a first inclined surface 2662 and a second inclined surface 2664 on a side close to the light source module 24 , and the first inclined surface 2662 and the second inclined surface 2664 are connected through a turning point 2666 . The first slope 2662 is between the substrate 22 and the inflection point 2666 . The second slope 2664 is between the inflection point 2666 and the top of the light permeable package 266 . There is a first inclination angle θ1 between the first inclined surface 2662 and the normal line 28 perpendicular to the surface 222 . There is a second inclination angle θ2 between the second inclined surface 2664 and the normal line 28 . The first inclination angle θ1 and the second inclination angle θ2 are both positive values, and the second inclination angle θ2 is greater than the first inclination angle θ1. In one embodiment, the first inclination angle θ1 is 4°˜6°, the second inclination angle θ2 is 50°˜80°, and the distance H1 between the turning point 2666 and the surface 222 is 0.056mm˜0.146mm, but the present invention is not limited to this. One end of the bonding wire 264 is located between the sensing chip 262 and the first inclined surface 2662 , and the other end is connected to a contact on the sensing chip 262 close to the first inclined surface.

FIG. 3 illustrates how FIG. 2 reduces internal leakage of light into the light permeable package 266 . When the light L1 emitted by the light emitting element 242 is transmitted in the light permeable package 244 , part of the light L2 may be emitted from the side of the light permeable package 244 , as shown in FIG. The emitted light L2 is called inner leakage light. Through equipment or optical simulation, the energy distribution 30 of the light leaking from the light source module 24 in the X direction and at the edge of the light permeable package body 266 can be obtained. Please note that, in FIG. 3 , the energy distribution 30 is only for illustrating the energy distribution of the internal leakage light, and the energy distribution 30 is not a physical object. In the energy distribution 30, the darker the color, the greater the energy of the inner leakage light. In the Y direction at the edge of the light permeable package 266 , the position 302 is the position where the maximum value of the internal leakage light energy is located. The position (ie, height) of the turning point 2666 of the light-transmitting package 266 in the Y direction is lower than the position 302 of the energy maximum in the energy distribution 30 in the Y direction. Therefore, the maximum energy of the internal leakage light will not enter the light-transmitting package body 266 from the first inclined surface 2662 . On the other hand, since the second inclined surface 2664 has a larger inclination angle, it is helpful to reflect more light L2, so as to avoid the sensing chip 262 from sensing the light L2 as much as possible. In other words, the present invention can reduce the internal light leakage into the light-transmitting package 266 , thereby reducing the noise floor (ACT) of the sensing chip 262 .

In the light sensor 20 of the present invention, the first inclination angle θ1 of the first inclined surface 2662 , the second inclination angle θ2 of the second inclined surface 2664 , the distance G1 between the transparent package body 266 and the light source module 24 , and Parameters such as the distance H1 between the turning point 2666 and the surface 222 will affect the noise floor of the sensing chip 262 . The larger the first tilt angle θ1 and the second tilt angle θ2, the lower the noise floor of the sensing wafer 262. The larger the distance G1 is, the smaller the noise floor of the sensing chip 262 is. The smaller the distance H1 is, the smaller the noise floor of the sensing chip 262 is.

In the embodiment of FIG. 2 , the side of the sensing chip 262 close to the light source module 24 is connected with a wire 264 . In other embodiments, the bonding wire 264 may not be disposed on the side of the sensing chip 262 close to the light source module 24. In this case, the first inclination angle θ1 and the second inclination angle θ2 can be increased to further reduce the noise floor .

In the embodiment of FIG. 2 , the transparent package body 266 has only two inclined surfaces 2662 and 2664 , but in other embodiments, the transparent package body 266 may also have three or more inclined surfaces.

The above descriptions are only the embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field, Within the scope of not departing from the technical solution of the present invention, when the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes, but any content that does not depart from the technical solution of the present invention, according to the technical essence of the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

20: Light sensor

22: Substrate

222: Surface

24: Light source module

242: Light-emitting element

244: light-transmitting package

26: Sensing module

262: Sensing chip

264: Wire

266: transparent package

2662: First Bevel

2664: Second Bevel

2666: Turning Point

28: Normal

G1: Gap

H1: Distance

L1: light

L3: Light

θ1: first tilt angle

θ2: Second tilt angle

Claims (8)

A light sensor, comprising: a substrate with a surface; a light source module arranged on the surface to provide a first light; a sensing chip arranged on the surface to sense incoming light The second light of the light sensor; and a transparent package body disposed on the surface and covering the sensing chip, there is a distance between the transparent package body and the light source module, the transparent package body and the light source module The side of the light package body close to the light source module has a first slope and a second slope connected with the first slope; wherein, there is a turning point between the first slope and the second slope, and the first slope is at Between the substrate and the turning point, the second slope is between the turning point and the top of the light-transmitting package; wherein, there is a first slope angle between the first slope and the normal line perpendicular to the surface, There is a second inclination angle between the second inclined plane and the normal line; wherein, the first inclination angle and the second inclination angle are positive values, and the second inclination angle is greater than the first inclination angle. The light sensor of claim 1, wherein the light-transmitting package is in a first direction of the light source module, and the turning point is lower than the energy maximum position of the first light in the first direction. The light sensor of claim 1, wherein the first inclination angle is between 4 degrees and 6 degrees, and the second inclination angle is between 50 degrees and 80 degrees. The light sensor according to claim 1, wherein the distance is between 0.3mm and 0.5mm. The light sensor of claim 1, wherein the distance between the turning point and the surface is 0.056mm~0.146mm. The light sensor of claim 1, wherein the light source module comprises a vertical cavity surface emitting laser or an LED. The light sensor of claim 1, wherein the second light is a reflected light of the first light. The light sensor of claim 1, further comprising a bonding wire connecting the sensing chip and the substrate, wherein a first end of the bonding wire is located between the sensing chip and the first slope, and a second end of the bonding wire is connected the sensing chip.

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