TWI721443B - Light source module with uniform projected light intensity - Google Patents

Abstract

The present invention provides a light source module with uniform projected light intensity, comprising at least one light-emitting element array, comprising a plurality of light emitting diodes. The light emitting diodes may be two first type light emitting diodes respectively having a first tilt angle; or at least one first type light emitting diode and at least one pair of second type light emitting diodes. The second type of light emitting diodes are disposed on the periphery of the first type of light emitting diodes, and each pair of the second type of light emitting diodes has a second tilt angle, and the second tilt angle is greater than the first tilt angle. By tilting or rotating the light emitting diodes, the light intensity distribution range on the projection surface is enlarged, so that the intensity of the irradiated light can be more uniform.

Description

Light source module with uniform projection light intensity

The present invention relates to a light source module, in particular to a light source module with uniform projection light intensity.

Depth sensors are mainly used in 3D sensing. Because traditional 2D plane image recognition only has X and Y axes, it is more susceptible to interference from factors such as shooting angle and ambient lighting when judging the depth of field of the image, while 3D sensing is More depth detection, from the plane X, Y axis to X, Y, Z three-axis three-axis three-dimensional coordinates, to capture the depth image of the target and obtain the three-dimensional information of the space, not only improves the accuracy of recognition, but also has a wider range of applications. , Where time of flight (TOF) is one of the depth sensing technologies. As shown in Figure 1, the light source module 100 is used to emit an active light source to project to the target, which is reflected by the target and then passed through the filter 110 filters the light, and then uses the light sensor 120 to receive the reflection of the relevant light source, and calculates the time phase difference through the time of the light return to obtain the depth information of the object to be measured. However, the uniformity of the light source projected on the object will affect the error of calculating the depth distance. Traditionally, infrared rays are used as the active light source, and the light intensity distribution of the light source projected on the object will vary with the beam angle.

However, the application of LEDs to depth sensors has the following disadvantages: a single LED has low power, in order to obtain high power, multiple parallel use is required; LEDs only have high brightness in a narrow angle of direct viewing, and the light will quickly weaken after deviating from this angle ; And the irradiation angle is limited, generally only 120°. In particular, the LED illumination angle is too small, the brightness of the exceeding range will be rapidly reduced, etc. Two points are the flaws of the depth sensor, because the LED light is too directional and the light is too concentrated, but the light intensity is not uniform enough, and the maximum is only The ability to illuminate 120° will affect the field of view angle of the light source, which limits the scope of application in space. The above-mentioned problems directly limit the application range of the 3D depth sensing system.

Therefore, the present invention proposes a light source module with uniform projected light intensity to effectively solve the above-mentioned problems. The specific structure and implementation methods will be described in detail below:

The main purpose of the present invention is to provide a light source module with uniform projected light intensity, which uses light-emitting diodes with different beam angles to form a light-emitting element array, and the middle part is a scattering light-emitting diode. The outer part is a standard light-emitting diode to make the light intensity uniform.

Another object of the present invention is to provide a light source module with uniform projected light intensity, which combines a plurality of light-emitting diodes in a light-emitting element array in pairs with different inclination or rotation angles of the centerline of the beam Change the illumination direction of the light-emitting diode to expand the light intensity distribution range on the projection surface.

Another object of the present invention is to provide a light source module with uniform projected light intensity, which can arrange multiple groups of light-emitting element arrays to enhance the light intensity at different working distances.

To achieve the above objective, the present invention provides a light source module with uniform projected light intensity, including: at least one light emitting element array, including: two first-type light emitting diodes, each having a first tilt angle; or at least one A first-type light-emitting diode and at least a pair of second-type light-emitting diodes, the second-type light-emitting diode system is arranged on the periphery of the first-type light-emitting diode, and each of the second-type light-emitting diodes The body has a second inclination angle, and the second inclination angle is greater than the first inclination angle.

According to an embodiment of the present invention, the first inclination angle is the angle between the beam center line of the first-type light-emitting diode and a vertical line, and the closer the first-type light-emitting diode is to the center of the light-emitting element array Otherwise, the first angle of inclination it has is smaller.

According to an embodiment of the present invention, the second inclination angle is the angle between the beam center line of the second-type light-emitting diode and a vertical line.

According to an embodiment of the present invention, the first-type light-emitting diode is a scattering type light-emitting diode, which further includes a first beam angle, which is the angle of the field of view of the first-type light-emitting diode. The first beam angle is about 45 to 90 degrees.

According to an embodiment of the present invention, the second-type light-emitting diode is a standard-type light-emitting diode, which further includes a second beam angle, which is the angle of the field of view of the second-type light-emitting diode. The second beam angle is about 20 to 45 degrees.

According to an embodiment of the present invention, when the number of the first-type light-emitting diodes is an even number, they are symmetrically inclined in pairs. The closer to the center, the smaller the first inclination angle. When the number of the first-type light-emitting diode is an odd number, the first inclination angle of the first-type light-emitting diode in the middle is zero.

According to an embodiment of the present invention, each of them is symmetrically inclined to the second-type light-emitting diode system. The closer the second-type light-emitting diode is to the edge of the light-emitting element array, the greater the second inclination angle it has.

The present invention provides a light source module with uniform projected light intensity, which can be used in a depth sensor as shown in Figure 1. In a light source module using a plurality of light-emitting diodes, the projection area is increased, and The uniformity of the light intensity on the projection surface solves the problem that when the light source is emitted in the prior art, the light intensity changes or attenuates the intensity distribution of the light projected on the projection surface due to the divergence of the light beam, resulting in poor light intensity uniformity.

Due to the limited brightness provided by a single light-emitting diode, in a large environmental space, in order to cope with the use of different working distances, it is necessary to connect multiple light-emitting diodes in parallel to provide sufficient brightness and field of view. It is a schematic diagram of the light-emitting element array of the present invention. The m*n light-emitting diodes 10 are arranged into a light-emitting element array 12.

In the present invention, assuming that there are only two light-emitting diodes 10 on the light-emitting element array 12, it is a first-type light-emitting diode. When the number of light-emitting diodes 10 is greater than two, it includes the first-type light-emitting diode. There are two types of light-emitting diodes and second-type light-emitting diodes. The first-type light-emitting diode in the middle is a scattering type light-emitting diode with a larger viewing angle. It is usually used as an indicator light, including about 45~ One of the first beam angle of 90 degrees, the beam angle is the angle between the field of view of the first type of light-emitting diode, and if the amount of scattering agent is increased, the first beam angle can be larger; the second type of light-emitting diode system Set at the periphery of the first type light emitting diode, this second type light emitting diode is a standard type light emitting diode, which includes a second beam angle of about 20 to 45 degrees, and is a second type light emitting diode The angle of the field of view.

In addition, the first and second type LEDs also have a first and a second tilt angle respectively. Please refer to Figure 3 at the same time. The tilt angle is the angle between the beam center line 16 of the light emitting diode and a vertical line 18 , Each pair of second-type light-emitting diodes is symmetrically inclined, and the second inclination angle is greater than the first inclination angle. Further, the second-type light-emitting diodes closer to the edge of the light-emitting element array have the first The second inclination angle can also be increased. In other words, the closer the second-type light-emitting diode is to the edge, the more inclined the angle of illumination can be, so that the light-emitting element array 12 can cover a larger field of view. The configuration of the first and second type light emitting diodes in the light emitting element array 12 will be described in detail below.

Please refer to Figure 3, which is a schematic diagram of the first embodiment of the light source module with uniform projection light intensity of the present invention. Since the number of light-emitting diodes is two, there is no distinction between the center and the edge, so they are all of the first type. The light-emitting diode 102, that is, the scattering light-emitting diode, the two first-type light-emitting diodes 102 are symmetrically inclined to each other, and are inclined or rotated outward based on the vertical line 18 of the light-emitting element array, respectively. A beam angle ψ ₁ and a first inclination angle θ _{1 of the} beam centerline 16. If the two first-type light-emitting diodes 102 do not have the first inclination angle θ ₁ , they are all irradiated vertically upwards, obviously the irradiated area will be reduced, and the luminosity of the overlapping part will be particularly bright, making the light intensity uneven. However, after the present invention inclines or rotates the light-emitting diode, not only a larger irradiation angle and irradiation area can be obtained, but also the light intensity can be uniform.

FIG. 4 is a schematic diagram of the second embodiment of the light source module with uniform projected light intensity according to the present invention, in which the number of light-emitting diodes is three. Since the number of light-emitting diodes is an odd number, the middle one is the first type light-emitting diode 102 (that is, the scattering type light-emitting diode), and its first tilt angle θ ₁ is 0 (not shown in the figure), and The two outer ones are second-type light-emitting diodes 104, that is, standard-type light-emitting diodes. The second inclination angle is θ _2. In addition, the first-type light-emitting diode 102 has a first beam angle ψ ₁ . The second-type light-emitting diode 104 has a second beam angle ψ _2. It can be seen from the figure that the first-type light-emitting diode 102 in the middle has a large field of view, while the second-type light-emitting diodes 104 on both sides have a large field of view. The field range is small, combined with the appropriate tilt or deflection θ _{2 of the} second-type light-emitting diode 104 to increase the field of view of the three light-emitting diodes 102 and 104, reduce the overlapping area of the illumination, and make the projection surface The light intensity is homogenized.

When the number of light-emitting diodes is greater than four and is an odd number, the number of first-type light-emitting diodes 102 can be one or an odd number. Except for the vertical arrangement in the middle, other first-type light-emitting diodes 102 is a pair of pairs with a first inclination angle θ ₁ . The second-type light-emitting diodes 104 themselves are arranged in pairs, which can include more than one pair. For example, if the number of light-emitting diodes is 7, it can include three first-type light-emitting diodes 102 (of which Two pairs) and two pairs of second-type light-emitting diodes 104; or only the middle one is the first-type light-emitting diode 102, and the remaining six are divided into three pairs of second-type light-emitting diodes 104, each For the same or different second inclination angle θ ₂ , when the second inclination angle θ _{2 is} different, the second type light emitting diode 104 closer to the periphery has the larger _{the second inclination angle θ 2.}

Fig. 5 is a schematic diagram of a third embodiment of a light source module with uniform projected light intensity according to the present invention, in which the number of light-emitting diodes is four. Since the number of light-emitting diodes is an even number, the middle one is a pair of first-type light-emitting diodes 102 (that is, scattering-type light-emitting diodes), which have a first inclination angle θ ₁ , so that two first-type light-emitting diodes The irradiation overlap area of the light-emitting diode 102 is reduced, and the outer two pieces are the second-type light-emitting diode 104, that is, the standard-type light-emitting diode, which has a second inclination angle of θ ₂ , so that the first and the second The overlapping area of the two light-emitting diodes 102 and 104 is reduced, and the field of view is increased. In addition, the first-type light-emitting diode 102 has a first beam angle ψ ₁ , and the second-type light-emitting diode 104 has a second beam angle ψ ₂ .

When the number of light-emitting diodes is greater than four and is an even number, the number of first-type light-emitting diodes 102 can be two or an even number, arranged in pairs in pairs, and have a first tilt angle θ ₁ . The second-type light-emitting diodes 104 themselves are arranged in pairs, which may include more than one pair. For example, if the number of light-emitting diodes is 8, it may include four (two pairs) first-type light-emitting diodes. Body 102 and two pairs of second-type light-emitting diodes 104, and the first inclination angle θ _{1 of the} two pairs of first-type light-emitting diodes 102 is the same or different. When the first inclination angle θ ₁ is different, the middle one The first inclination angle θ _{1 is relatively small, and the second inclination angle θ 2 of the} two pairs of second-type light-emitting diodes 104 may be the same or different. When the second inclination angle θ ₂ is different, the second inclination of the outer The angle θ _{2 is} relatively large; or only the middle pair is the first-type light-emitting diode 102, and the remaining six are divided into three pairs of the second-type light-emitting diode 104, and each pair has the same or different second When the inclination angle is θ ₂ and the second inclination angle θ _{2 is} different, the closer the second-type light emitting diode 104 is to the periphery, the greater the second inclination angle θ _{2 is} .

The light source module of the present invention can be fabricated on a substrate of any material, and the material of the substrate is not limited.

其中Ｉ_max 為最大光強度，Ｉ_光束角 為發光二極體的光束角不同時之光強度。The formula for the uniformity of light intensity in the present invention is as follows:

Among them, I _max is the maximum light intensity, and I _{beam angle} is the light intensity of the light-emitting diode at different beam angles.

The following uses actual experimental data as an example for description. When the number of light-emitting diodes in the light source module is three, it is assumed that the beam angle of the first type light-emitting diode in the middle is 90 degrees, and the beam angle of the second row of light-emitting diodes on both sides is 45 degrees. Then the relationship between light intensity and polar coordinates is shown in Figure 6. Then simulate the light intensity distribution. Figure 7A is a schematic diagram of the light intensity distribution simulation of the normalized light intensity corresponding to the emission angle (LED tilt angle) in the prior art. It can be seen that the light intensity is concentrated in the middle position, and the light intensity will drop rapidly to both sides. Fig. 7B and Fig. 7C are the simulated schematic diagrams of the light intensity distribution of two second-type light-emitting diodes inclined at 40 degrees and 50 degrees respectively. Obviously, when the structure is inclined at 40 degrees, the total light intensity is progressive. A gentle slope descends, rather than a rapid descent.

Fig. 8 is a simulated schematic diagram of light intensity distribution when two first-type light-emitting diodes have different inclination angles in the first embodiment of the present invention. It can be clearly seen from the figure that when the angle of tilt or rotation of the light-emitting diode is different, it has a great influence on the light intensity distribution. When the tilt angle is greater than 27 degrees, the light intensity is obviously more uniform.

Figure 9 is a schematic diagram of the field angle variation simulation of the light intensity at 20% uniformity when the beam center lines of two first-type light-emitting diodes are inclined (or rotated) at different angles in the first embodiment of the present invention. This part uses Zemax to simulate a first-type light-emitting diode with a symmetrical beam angle of 90°, with different optical axis tilt/rotation angles θ=0°, 3°, 6°, 9°, 12°, 15°, Light intensity distribution at 18°, 21°, 24°, 27° and 30°. According to the light intensity uniformity defined by the above formula, the field angle change when the light intensity uniformity is 20% is summarized. When θ>24 degrees, the angle of view expands rapidly.

Figure 10 is a simulated schematic diagram of light intensity changes at different working distances when the inclination angle of two first-type light-emitting diodes is 27 degrees in the first embodiment of the present invention. The greater the working distance, the smaller the light intensity.

In summary, the light source module with uniform projected light intensity of the present invention includes a plurality of pairs of light emitting diodes that are symmetrical to each other, and the symmetry is performed at a tilt/rotation angle of the center line of the beam, and When the number of LEDs is an odd number, the one in the middle will not tilt/rotate, and the rest will tilt or rotate symmetrically, and the tilt angle can be adjusted freely. At the same time, the present invention uses LEDs with different beam angles, where the inner side is the beam The first type LED with a larger angle, the second type LED with a smaller beam angle is used on the outside to reinforce the light intensity at different angles to optimize the uniformity of the light intensity at different angles, and the beam angle can also be Free adjustment. When the working distance increases, the light intensity will become weaker, so the present invention can also increase the number of light-emitting diodes (for example, light up another light-emitting element array next to it) to optimize the brightness of the working distance. Therefore, the present invention can not only uniformize the light intensity of the projection surface, but also expand the projection range, save the need for the design of the optical diffusion film, and is beneficial to take into account the uniformity of the light intensity and reduce the production cost.

Only the above are only preferred embodiments of the present invention, and are not used to limit the scope of implementation of the present invention. Therefore, all equivalent changes or modifications made in accordance with the characteristics and spirit of the application scope of the present invention shall be included in the patent application scope of the present invention.

100: light source module 110: filter 120: light sensor 10: Light-emitting diode 102: The first type of light-emitting diode 104: Type 2 LED 12: Light-emitting element array 16: beam centerline 18: vertical line

Figure 1 is a schematic side view of a depth sensor applied to it. Figure 2 is a schematic diagram of the light-emitting element array of the present invention. Figure 3 is a schematic diagram of the first embodiment of the light source module with uniform projected light intensity according to the present invention, in which the number of light-emitting diodes is two. Figure 4 is a schematic diagram of the second embodiment of the light source module with uniform projected light intensity according to the present invention, in which the number of light-emitting diodes is three. Figure 5 is a schematic diagram of a third embodiment of a light source module with uniform projected light intensity according to the present invention, in which the number of light-emitting diodes is four. Figure 6 is a diagram showing the relationship between the light intensity of the light source module to which the present invention is applied to the polar coordinates. Figure 7A is a schematic diagram of the light intensity distribution simulation of the normalized light intensity corresponding to the emission angle (LED tilt angle). Fig. 7B and Fig. 7C are respectively schematic diagrams of simulated light intensity distribution of two second-type light-emitting diodes inclined at 40 degrees and 50 degrees in the second embodiment of the present invention. Fig. 8 is a simulated schematic diagram of light intensity distribution when two first-type light-emitting diodes have different inclination angles in the first embodiment of the present invention. Figure 9 is a schematic diagram of the field angle variation simulation of the light intensity at 20% uniformity when the beam center lines of two first-type light-emitting diodes are inclined (or rotated) at different angles in the first embodiment of the present invention. Figure 10 is a simulated schematic diagram of light intensity changes at different working distances when the inclination angle of two first-type light-emitting diodes is 27 degrees in the first embodiment of the present invention.

Claims (9)

A light source module with uniform projection light intensity, comprising: at least one light-emitting element array, including a plurality of light-emitting diodes, which are at least one first-type light-emitting diode and at least a pair of second-type light-emitting diodes. The first-type light-emitting diodes respectively have a first inclination angle, and the first-type light-emitting diodes are scattering light-emitting diodes, which further include a first beam angle, which is the first-type light-emitting diodes The angle of the field of view of the body, and the second-type light-emitting diode system is arranged on the periphery of the first-type light-emitting diode. Each of the second-type light-emitting diodes has a second inclination angle. The inclination angle is greater than the first inclination angle, and the second-type light-emitting diode is a standard light-emitting diode, which further includes a second beam angle, which is the angle of the field of view of the second-type light-emitting diode , The first beam angle is greater than the second beam angle. The light source module with uniform projection light intensity according to claim 1, wherein the first inclination angle is the angle between the beam center line of the first-type light-emitting diode and a vertical line, and the first-type light-emitting diode The closer the polar body is to the center of the light-emitting element array, the smaller the first inclination angle it has. The light source module with uniform projection light intensity according to claim 1, wherein the second inclination angle is the angle between the beam center line of the second-type light-emitting diode and a vertical line. The light source module with uniform projected light intensity according to claim 1, wherein the first beam angle is about 45 to 90 degrees. The light source module with uniform projected light intensity according to claim 1, wherein the second beam angle is about 20 to 45 degrees. The light source module with uniform projected light intensity as described in claim 1, wherein when the number of the first-type light-emitting diodes is even, they are paired in pairs and inclined symmetrically, the closer to the center, The first angle of inclination is smaller. The light source module with uniform projected light intensity as described in claim 1, wherein each of them is symmetrically inclined to the second-type light-emitting diode system. The light source module with uniform projection light intensity according to claim 1, wherein the second type of light emitting diode closer to the edge of the light emitting element array has the greater the second inclination angle. The light source module with uniform projected light intensity according to claim 1, wherein when the number of the first-type light-emitting diode is an odd number, the first inclination angle of the first-type light-emitting diode in the middle is 0.

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