WO2018133320A1 - Optical projection apparatus and depth camera applying same - Google Patents

Abstract

An optical projection apparatus (3) comprises a base (10) capable of heat dissipation, a light-emitting chip, and a beam former. The base (10) comprises a reinforcing base plate (27) and a circuit board (26). The light-emitting chip is a VCSEL chip (25). The VCSEL chip (25) comprises a semiconductor substrate (18) and at least two VCSEL light sources (24) arranged on the semiconductor substrate (18). A first beam emitted by the VCSEL chip (25) is consistent with a pattern in which the VCSEL light sources (24) are arranged. The beam former comprises a lens seat (13, 14), a lens (15), and an optical diffraction element (16), or comprises a lens seat (13, 14) and a diffuser. A depth camera comprises the optical projection apparatus (3), an image acquisition apparatus (4), and a processor (1), or comprises the optical projection apparatus (3), a beam receiving apparatus (8), and a processor (1). The optical projection apparatus (3) has a small size, high heat dissipation performance, and stable structure, and can be integrated as a part of a depth camera into a micro-computing device.

Description

Optical projection device and depth camera using the same [Technical Field]

The present invention relates to the field of optical and electronic technologies, and in particular, to an optical projection device and a depth camera using the same.

【Background technique】

The depth camera can acquire the depth information of the target to achieve 3D scanning, scene modeling, and gesture interaction. Compared with the currently widely used RGB cameras, the depth camera is gradually receiving attention from various industries. For example, the combination of a depth camera and a television, a computer, etc. can realize a somatosensory game to achieve the effect of a game fitness two-in-one. Microsoft's KINECT and Aubi's ASTRA are among them. In addition, Google's tango project is dedicated to bringing depth cameras to mobile devices, such as tablets and mobile phones, to bring a completely subversive experience, such as a very realistic AR gaming experience, which can be used for indoor map creation and navigation. And other functions.

The core component in depth cameras is optical projection devices, and as applications continue to expand, optical projection devices will evolve to smaller and smaller volumes and higher performance. Generally, an optical projection device is composed of a circuit board, a light source and the like. At present, a wafer-level vertical cavity surface emitting laser (VCSEL) array light source can reduce the volume of the optical projection device to be embedded in a microelectronic device such as a mobile phone. . In the prior art, VSCEL can be fabricated on a semiconductor substrate, and the semiconductor substrate is connected to a flexible circuit board (FPC). In order to solve the heat dissipation problem, a semiconductor cooler (TEC) is also introduced. TEC can control the heat of the light source very well, but due to its high power consumption and occupying a large volume, the volume and power consumption of this type of optical projection device are still not ideal.

[Summary of the Invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical projection apparatus and a depth camera using the same that solves the problem of providing both the volume and the heat dissipation effect of the optical projection apparatus of the prior art.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

An optical projection device, comprising:

a base having a heat dissipation performance;

a light emitting chip, the light emitting chip is mounted on the base and electrically connected to the base and used to emit a first light beam;

a beam generator mounted on the base and configured to receive the first beam and project a second beam outward.

Preferably, the base comprises:

Reinforcing the bottom plate, the reinforcing bottom plate having a heat conducting and supporting function;

a circuit board, the circuit board being connected to the reinforcing bottom plate;

Preferably, the light emitting chip is a VCSEL chip, and the VCSEL chip comprises:

Semiconductor substrate

Having at least two VCSEL light sources arranged on a semiconductor substrate;

The first light beam emitted by the VCSEL chip is consistent with the pattern of the VCSEL light source arrangement.

Preferably, the beam generator comprises:

a lens holder, the lens holder being mounted on the base;

a lens mounted on the lens holder for collimating the first light beam;

a diffractive optical element mounted on the mirror mount for receiving the first beam collimated by the lens and projecting the second beam outward.

Preferably, the beam generator comprises:

a lens holder, the lens holder being mounted on the base;

a diffuser mounted on the mirror mount for diffusing the first light beam and projecting the second light beam outward.

Preferably, the reinforcing bottom plate is a hard bottom plate having heat conductive properties or a hard bottom plate having heat conductive properties.

Preferably, the circuit board has a hole in the middle, the size of the light emitting chip is smaller than the size of the hole; the light emitting chip is placed in the hole and the bottom is thermally connected with the reinforcing substrate; the light emission The two electrodes of the chip are electrically connected to the circuit board and the reinforcing substrate, respectively, and the reinforcing substrate is electrically connected to the circuit board; or the two electrodes of the light emitting chip are electrically connected to the circuit board.

Preferably, the circuit board is one or a combination of a printed circuit board, a flexible circuit board, and a soft and hard bonding board.

Preferably, the circuit board is provided with a plurality of pads, and the pads are electrically connected to the base or/and the light emitting chip.

Preferably, the lens holder includes upper and lower mirror mounts, and the lower mirror mount is mounted on the base, wherein the lens is fixed with the diffractive optical element and connected to the lower mirror mount. The connection can be used to adjust the distance between the beam generator and the light emitting chip.

Preferably, the mirror base comprises upper and lower mirror mounts, wherein the lower mirror mount is mounted on the base, the diffuser is fixed in the upper mirror mount and connected to the lower mirror mount, and the connection can be used The distance between the beam generator and the light emitting chip is adjusted.

Preferably, the lens is a microlens array, and the diffractive optical element is designed as a single optical element.

Preferably, the depth camera is used to acquire a depth image of the target to be measured.

The invention has an advantageous effect of providing an optical projection device and a depth camera using the same, the optical projection device comprising a base having heat dissipation performance, a light emitting chip and a beam generator, so that the optical projection device has small volume and high heat dissipation performance. The structural stability feature can be integrated into a micro-computer device as part of a depth camera.

[Description of the Drawings]

1 is a side elevational view of a structured light depth camera system in accordance with an embodiment of the present invention.

2 is a side view of a TOF depth camera system in accordance with an embodiment of the present invention.

Figure 3 is a side elevational view of an optical projection device in accordance with an embodiment of the present invention.

4 is a schematic structural view of a vertical cavity surface laser emitter according to an embodiment of the present invention.

Figure 5 is a front elevational view of a VCSEL chip in accordance with an embodiment of the present invention.

6 is a schematic view of a base of an optical projection device according to an embodiment of the present invention.

Figure 7 is a front elevational view of the base of the optical projection device of the embodiment of the present invention.

8 is a plan view of a base of an optical projection device according to an embodiment of the present invention, wherein FIG. 8-a is a top view of a base of a rigid bottom plate of a base of the optical projection device according to the embodiment of the present invention, wherein the reinforcing bottom plate is a heat conductive and conductive property, and FIG. The reinforcing bottom plate of the base of the optical projection device of the embodiment of the present invention is a top view of the base of the hard substrate with thermal conductivity.

Figure 9 is a schematic illustration of an optical projection device in accordance with an embodiment of the present invention.

Among them, 1-processor, 2-board, 3-optical projection device, 4-image acquisition device, 5-interface, 6-RGB camera, 7-light window, 8-beam receiver, 9-light pulse, 10 - base, 11-light source, 13-upper holder, 14-lower holder, 15-lens, 16-diffractive optical element (DOE), 17-bottom electrode, 18-semiconductor substrate, 19-P type semiconductor mirror, 20-active layer, 21-limiting layer, 22-N type, 23-top electrode, 24-VCSEL light source, 25-VCSEL array chip, 26-circuit board, 27-reinforced bottom plate, 28-pad, 29-gold line.

【detailed description】

The present invention provides an optical projection device and a depth camera using the same. Embodiments of the invention are described in detail below. It is to be understood that the following description is only illustrative, and is not intended to limit the scope of the invention. The depth camera to which the optical projection device is applied will be described in the embodiment, but it does not mean that the optical projection device can be applied only in the depth camera, and any other device should be included in the direct or indirect use of the solution. In the claims of the present invention.

Example 1

A side view of a structured light based depth camera as shown in FIG. The main components of the structured light-based depth camera are an optical projection device 3, an image capture device 4, a main board 2, and a processor 1, and an RGB camera 6 is also provided in some depth cameras. The optical projection device 3, the image capture device 4, and the RGB camera 6 are generally mounted. On the same depth camera plane, and at the same baseline, each device or camera corresponds to a light entrance window 108. In general, the processor 1 is integrated on the main board 2, and the optical projection device 3 and the image acquisition model 4 are connected to the main board via the interface 5, which in one embodiment is an FPC interface. The optical projection device 3 is configured to project the encoded structured light pattern into the target space, and the image acquisition device collects the structured light image and processes the processor to obtain a depth image of the target space. In one embodiment, the structured light image is an infrared laser speckle pattern, the pattern having a relatively uniform particle distribution but having a high local irrelevance, where local uncorrelation refers to a higher sub-region in the pattern. Uniqueness. The corresponding image capture device 4 is an infrared camera corresponding to the optical projection device 3. The acquisition of the depth image by the processor specifically refers to further obtaining the depth image by calculating the deviation value between the speckle pattern and the reference speckle pattern after receiving the speckle pattern acquired by the image acquisition device.

Example 2

Figure 2 shows a side view of a depth camera based on Time Flight Principle (TOF). The main components of the time-of-flight (TOF) based depth camera are also the optical projection device 3' and the beam receiving device 8, and also include the main board 2, the processor 1, and the RGB camera 6. The optical projection device 3, the image capture device 4, and the RGB camera 6 are generally mounted on the same depth camera plane and at the same baseline. The connection to the motherboard can select the FPC connection 5, and each device or camera corresponds to one. Into the light window 7. Different from the structured light depth camera, the optical projection device 3' is used to emit the chronograph light pulse 9, and the light beam receiving device 8 collects the light pulse 9 to obtain the flight time of the light in space, and then uses the processor. Calculate the distance of the corresponding spatial point.

Although the composition of the depth camera of Embodiment 2 is similar to that of Embodiment 1, the specific structure of each component may differ depending on the principle. The invention mainly focuses on an optical projection device. The optical projection device of the structured light depth camera emits a coded structured light pattern to a target space, and the optical projection device of the TOF depth camera emits a light pulse to a target space, so that the internal structure thereof has the difference.

The same is true for the light source, and in some embodiments, both cameras use an infrared laser as their light source. At present, a single depth camera is mostly used as an independent peripheral device, and is connected to other devices such as a computer or a mobile phone through a data interface such as USB, and transmits the acquired depth information to other devices for further processing. With the increasing use of depth cameras, integrating and integrating depth cameras with other devices will be the future direction. In the integration of the motherboard and the processor, the motherboard, the processor of the depth camera, the motherboard and the processor of the computer mobile phone can be integrated; in the integration of the acquisition camera and the laser projection device, the large computer and other large devices are currently related. Solution, however, for small devices such as mobile phones, only a small laser projection device can meet the requirements. A preferred solution to meet these requirements is to use a VCSEL array laser. On the other hand, since laser projection has a large power consumption and a large amount of heat generation, it is also a necessary performance of an optical projection device to have high heat dissipation.

Example 3

3 is an embodiment of an optical projection apparatus in Embodiment 1. The projection apparatus includes a base 10, a light source 11, upper and lower mirror mounts 13 and 14, a lens 15, and a diffractive optical element (DOE) 16. The lens 15 and the DOE 16 together form a beam generator, and the first beam emitted by the source 11 is collimated by the lens 15 and then emitted by the DOE 16 to the space as a second beam. Typically the lens 15 is located between the source 11 and the diffractive optical element 16, and the distance between the lens 15 and the source 11 is preferably equal to the focal length of the lens. In other embodiments, lens 15 and DOE 16 may also be integrated into one optical component. The upper and lower mirror mounts can be connected by screw connection or direct contact. The former method is convenient for adjusting the focal length, and the latter method is more troublesome to adjust, but the optical axis can be adjusted in addition to the focal length. The base 10 on the one hand requires sufficient hardness to support the light source and on the other hand requires a higher heat dissipation.

In some embodiments, the laser projection device of the TOF depth camera of Embodiment 2 may also be shown in FIG. Unlike the laser projection device of the first embodiment, the lens 15 and the diffractive optical element (DOE) 16 refer to a combination of diffusing optical elements, and there may be only one optical element or three or more. Optical component composition.

The volume of the optical projection device affects the size of the entire depth camera, and the size of the light source 11 and the base 10 is an important factor affecting the volume of the laser projection device.

Example 4

As shown in FIG. 4 is a schematic structural diagram of a single VCSEL. In the choice of light source, the vertical cavity surface laser emitter (VCSEL) has the advantages of small volume, small light source emission angle, good stability, etc., which can be used as a light source of the projection device to reduce the overall volume. Generally, the active layer 20 of the VCSEL is in the middle, and the active layer is connected to the limiting layer 21. The limiting layer functions to control the light field and current to control the shape of the laser, etc. There are P-type and N-type semiconductor mirrors 19 and 22, the other side of the mirror 22 is a top electrode 23 (P pole, positive), and one side of the mirror 19 is a semiconductor substrate 18 and a bottom electrode 17 (N Extreme, negative).

Figure 5 shows a schematic of a VCSEL array. When the power of a single VCSEL source is not up to the application requirements, the source power can be increased by arranging a plurality of VCSELs 24 in an array on the same semiconductor substrate 18, and multiple VCSELs can be simultaneously fabricated on the same semiconductor substrate. Light sources can also greatly increase manufacturing efficiency. The VCSEL array chip 25 is currently at the wafer level scale, i.e., hundreds of VCSEL sources can be placed on a 1 mm2 chip. The control of the light source can have different modes. In one embodiment, all of the VCSEL light sources on the chip are synchronously controlled to be turned on and off; in another embodiment, the VCSELs on the chip are controlled independently or in groups to produce different Light density. The form and arrangement of the VCSEL 24 can be various according to specific application requirements, such as uniformly or regularly arranged or irregularly arranged in a certain unrelated pattern. The shape and area of a single VCSEL may also be different. Formal irregularities can lead to a reduction in manufacturing efficiency.

In some embodiments, the VCSEL chip can also be packaged for special purposes, similar to a computer's CPU. Wait for the chip to connect the positive and negative terminals to the outside on the same side by connecting them to the pins. For the depth camera embodiment of the present invention, since the volume is small, a preferred processing method is to directly place the unpackaged VCSEL semiconductor chip chip on the base 10. The bottom of the chip is connected to the negative electrode and the top is connected to the positive electrode. In the following description, a VCSEL chip chip will be described as an example, but it should be understood that a package chip is also included in the scope of the present invention.

Compared to edge-emitting lasers, VCSEL chips have a smaller footprint and higher light-emitting power, and VCSEL chips have less effect on temperature when illuminated. In one embodiment, the VCSEL chip is used as the light source 11 of the laser projection device in the structured light depth camera, and the first beam pattern emitted coincides with the pattern of the VCSEL source arrangement on the VCSEL chip, when the first beam is collimated by the lens 15 The DOE 16 emits a second beam into the space. Generally, the number of the second beam is much larger than the number of the first beam, and the pattern formed by the second beam should be a composite of the first beam pattern. For details, see the details. Chinese patent application 201610977171.9 and 201610977172.3.

Example 5

As shown in Figure 3, the chip needs to have a carrying and connecting mechanism to ensure the normal function of the chip. For example, the computer CPU has a card-type connection and fixing mechanism independently designed for it; for some special chips with little heat, it is directly connected to the main board through the pins; and the chip described in the present invention is a VCSEL array chip. Because it is used to emit a light beam, it requires a large power, generates a large amount of heat, and needs to be integrated into a small-sized micro device, and the heat dissipation problem needs to be solved; on the other hand, for the optical projection device, the base 10 is also It is necessary to carry the mirror mounts 14, 13 containing the optical elements, thus requiring the base to have sufficient strength to ensure a stable light emission output. Therefore, the base requires a small volume for integration, and requires better heat dissipation and a stable connection.

As shown in FIG. 6, in one embodiment, the base 10 of FIG. 3 is configured as a chip embedding device as shown in FIG. 6, including a circuit board 26 and a reinforcing bottom plate 27, which are joined together. The circuit board 26 is connected to the electrode through its interface 5 to supply or control the VCSEL chip 25. 27 is a reinforcing substrate for placing the VCSEL chip, and is connected with the VCSEL chip to function as a heat sink or an electrode. The commonly used material is copper-plated gold. Ceramics, etc. The device can be conveniently connected to other control units such as a motherboard, and can stably support the chip.

In one embodiment, in order to reduce the overall volume, a form of holes is added in the middle of the circuit board 26, the reinforcing bottom plate 27 is glued to the circuit board 26, and the holes are covered (generally, the hole center and the circuit board 602) The middle is coincident), then the chip is placed in the hole and connected to the substrate. The advantage of this arrangement is that both the connection between the board and the chip and the overall thickness control can be achieved.

In one embodiment, the circuit board 26 is a flexible circuit board (FPC), the reinforcing bottom plate 27 is a copper gold plated material, the VCSEL chip is located at the center of the hole, and is connected to the reinforcing bottom plate 27 through the conductive silver paste, and the bottom plate 27 and the circuit are reinforced. The plate 26 is glued. Some pads are placed around the holes of the FPC, and the pads are connected to the interface 5 through the wires.

In the pad 28 in the embodiment shown in FIG. 7, the positive electrode pad is connected to the top electrode of the VCSEL chip through the gold wire 29, and the negative electrode pad is directly connected to the reinforcing substrate 27, since the reinforcing bottom plate 27 and the bottom electrode of the chip pass the conductive silver. The paste is connected, thus achieving an indirect connection of the pad to the bottom electrode. In addition, since the VCSEL chip 25 is connected to the reinforcing substrate 27, and the reinforcing substrate 27 has good thermal conductivity, the heat dissipation problem of the VCSEL chip 25 is also solved.

In one embodiment, the circuit board 26 is physically connected to the reinforcement floor 27, such as a bolt or the like. If the glue is used for connection, the advantage is that it does not occupy space and is convenient to operate, but the disadvantage is that the resistance of the glue is large, which is not conducive to heat dissipation and increases power consumption. The specific connection method is not limited herein.

In one embodiment, the circuit board 26 is a printed circuit board (PCB) or a soft and hard bonded board. Compared with the FPC, the PCB has high hardness and good carrying performance, but the connection is more difficult. Therefore, in one embodiment, a combination of the two is adopted, that is, the FPC is used in the interface where the interface is located, and the soft and hard bonding plate is used in the portion connected to the substrate.

As shown in Fig. 8-a, the circuit board 26 is connected to the chip 25 and the reinforcing substrate 27 via gold wires 29, respectively. Generally, the hole size of the circuit board should be larger than the size of the chip 25. On the one hand, it is easy to install and leave an operation gap for the connection of the gold wire 29 and the reinforcing bottom plate 27, and on the other hand, the heat dissipation performance of the reinforcing bottom plate 27 is further improved. The shape of the hole is generally circular or square, and is not limited herein.

In one embodiment, the gold wire for connection may also be any other material that can achieve an electrically conductive connection.

As shown in Figure 8-b, in order to further reduce the volume, the chip can be recessed on the substrate, which can further reduce the overall thickness. It should be noted that it is not recommended to open the groove when the thickness of the substrate itself is thin to avoid deformation of the substrate material when the chip is heated.

In one embodiment, the substrate can also be other thermally conductive material, such as ceramic. At this time, the VCSEL chip is only thermally connected to the substrate, and is electrically connected to the positive and negative electrodes of the circuit board, and the connection manner may adopt any other manner in which the conductive connection can be realized, which is not limited herein.

In some embodiments, the substrate may also be designed to be suitable for heat dissipation, such as adding fan blades or the like to increase heat dissipation area and the like. The substrate can also be connected to other heat dissipating materials during integration with devices such as mobile phones to improve thermal performance.

Example 6

As shown in Fig. 9, an embodiment of an optical projection device in which the lens holders 13, 14 are directly connected to the circuit board 26, and the circuit board 26 is connected to the reinforcing substrate 27, in which the circuit board 26 is preferably FPC-compliant. In the form of PCB bonding, in which the PCB is connected to the reinforcing base plate and the mirror base, the stability of the lens holder can be improved. In another embodiment, the mirror mount can also be connected directly or indirectly to the reinforcing floor.

Claims (13)

An optical projection device, comprising: a base having a heat dissipation performance; a light emitting chip, the light emitting chip is mounted on the base and electrically connected to the base and used to emit a first light beam; a beam generator mounted on the base and configured to receive the first beam and project a second beam outward. The optical projection device of claim 1 wherein said base comprises: Reinforcing the bottom plate, the reinforcing bottom plate having a heat conducting and supporting function; a circuit board, the circuit board being connected to the reinforcing bottom plate; The optical projection device of claim 1, wherein the light emitting chip is a VCSEL chip, and the VCSEL chip comprises: Semiconductor substrate Having at least two VCSEL light sources arranged on a semiconductor substrate; The first light beam emitted by the VCSEL chip is consistent with the pattern of the VCSEL light source arrangement. The optical projection device of claim 1 wherein said beam generator comprises: a lens holder, the lens holder being mounted on the base; a lens mounted on the lens holder for collimating the first light beam; a diffractive optical element mounted on the mirror mount for receiving the first beam collimated by the lens and projecting the second beam outward. The optical projection device of claim 1 wherein said beam generator comprises: a lens holder, the lens holder being mounted on the base; a diffuser mounted on the mirror mount for diffusing the first light beam and projecting the second light beam outward. The optical projection device according to claim 2, wherein the reinforcing substrate is a rigid substrate having thermally conductive properties or a rigid substrate having thermally conductive properties. The optical projection device of claim 6 wherein: a hole is formed in the middle of the circuit board, and a size of the light emitting chip is smaller than a size of the hole; The light emitting chip is disposed in the hole and the bottom is thermally connected to the reinforcing substrate; The two electrodes of the light emitting chip are electrically connected to the circuit board and the reinforcing substrate, respectively, and the reinforcing substrate is electrically connected to the circuit board; or the two electrodes of the light emitting chip are electrically connected to the circuit board . The optical projection device of claim 2, wherein the circuit board is one or a combination of a printed circuit board, a flexible circuit board, and a soft and hard bonded board. The optical projection device according to claim 2, wherein said circuit board is provided with a plurality of pads, said pads being electrically connected to said base or/and said light emitting chip. The optical projection device according to claim 4, wherein said lens holder comprises upper and lower mirror holders, said lower mirror holder being mounted on said base, said lens and said lens being fixed in said upper lens holder The diffractive optical element is coupled to the lower mirror mount and the connection can be used to adjust the distance between the beam generator and the light emitting chip. The optical projection device according to claim 5, wherein said lens holder comprises upper and lower lens holders, wherein said lower lens holder is mounted on said base, said diffuser being fixed in said upper lens holder And connected to the lower mirror mount, the connection can be used to adjust the distance between the beam generator and the light emitting chip. The optical projection device of claim 4 wherein said lens is a microlens array and said diffractive optical element is designed as a single optical element. A depth camera employing the optical projection device of any of claims 1-12, the depth camera for acquiring a depth image of a target being measured.

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