Optical system device

Abstract

The purpose of the present invention is to provide an optical system device further miniaturized than an existing optical system device and capable of suppressing accumulation of heat generated in a light irradiation means and a control unit.　An optical system device 100 comprises: a light irradiation means 1 capable of emitting light; a control unit 2 that is electrically connected to the light irradiation means 1 and controls irradiation of the light irradiation means; and a heat radiation unit 3 that has at least a range of an irradiation angle of the light irradiation means 1 being light-transparent and is connected to the light irradiation means 1 and the control unit 2 so as to be thermally conductive. The heat radiation unit 3 seals surfaces of the light irradiation means 1 and the control unit 2 so as ensure no contact with gas.

Description

optical system equipment

[0001] This invention relates to an optical system.

[0002] Three-dimensional measurement sensors using the time-of-flight (TOF) method are being adopted in portable devices, cars, robots, and other applications. The time-of-flight (TOF) method measures the distance to an object by measuring the time it takes for light emitted from a light source to reflect back onto the object. For example, if light from a light source is uniformly emitted over a predetermined area of ​​the object, the distance at each illuminated point can be measured, making it possible to detect the three-dimensional structure of the object.

[0003] The above sensor system consists of a light-emitting unit that illuminates the object, a light-receiving unit such as a camera that detects the light reflected from each point of the object, and a calculation unit that calculates the distance to the object from the signals received by the light-receiving unit.

[0004] Since the light-receiving unit and the processing unit can use existing CMOS imagers and CPUs, the unique part of the above system is the light-emitting unit. As the light-emitting unit, for example, an optical system device mainly composed of an optical element such as a lens and a light irradiation means such as a VCSEL for irradiating the optical element with light has been considered (for example, Patent Document 1).

[0005] There has been a demand for miniaturization of these devices, and progress has been made in miniaturizing and integrating light irradiation means and optical elements used in the light-emitting section.

[0006] Japanese Patent Application No. 2022-182910

[0007] On the other hand, the light irradiation means has a control unit that is electrically connected to it, such as a VCSEL driver for controlling the VCSEL, and controls the intensity and duration of the light. Conventionally, the light irradiation means and the control unit were arranged on a plane and electrically connected. However, integrating the light irradiation means and the control unit in parallel in this way increases the mounting area. Therefore, stacking the light irradiation means and the control unit vertically is considered. However, simply stacking them would cause heat generated in the light irradiation means and the control unit to accumulate due to the low thermal conductivity of gas, leading to malfunctions.

[0008] Therefore, the present invention aims to provide an optical system that is even smaller than existing optical systems and can suppress the accumulation of heat generated in the light irradiation means and control unit.

[0009] To achieve the above objective, the optical system of the present invention is characterized by comprising: a light irradiation means capable of irradiating light; a control unit electrically connected to the light irradiation means and controlling the irradiation of the light irradiation means; and a heat dissipation unit in which at least the irradiation angle range of the light irradiation means is transparent to the light and is thermally conductively connected to the light irradiation means and the control unit.

[0010] In this case, it is preferable that the heat dissipation section is sealed so that the surface of the light irradiation means does not come into contact with the gas.

[0011] Furthermore, it is preferable that the heat dissipation section is sealed so that the surface of the control unit does not come into contact with gas.

[0012] Furthermore, the heat dissipation portion is preferably made of a resin with a thermal conductivity of 0.2 W / m·K or higher, and more preferably of a resin with a thermal conductivity of 1.0 W / m·K or higher.

[0013] The light irradiation means may also include an optical element having an uneven shape that exhibits optical functionality with respect to the light irradiated by it. In this case, the optical element may be laminated on the surface of the heat dissipation section.

[0014] Furthermore, the optical element consists of lenses that transmit light of wavelength λ arranged periodically, where m and n are natural numbers of 1 or more, and the focal length is determined by the cross-sectional shape of the lens perpendicular to the y-direction. １ The focal length is determined by the cross-sectional shape perpendicular to the x-direction, f ２ The size of the x-direction pitch of the lens is P １ The size of the pitch in the y direction is P ２ Therefore, the distance L between the irradiating portion and the first focal plane of the lens. １ , distance L from the second focal plane ２ However, see equations 1 and 2 below. It may also satisfy the following conditions.

[0015] The optical system of the present invention can reduce the footprint (area occupied) by stacking the VCSEL and driver. Furthermore, since the VCSEL and driver are covered with a solid that has a higher thermal conductivity than gas, the generated heat can be dissipated.

[0016] This is a schematic cross-sectional view showing an optical system of the present invention. This is a schematic cross-sectional view showing another optical system of the present invention. This is a schematic cross-sectional view showing another optical system of the present invention. This is a schematic cross-sectional view showing another optical system of the present invention.

[0017] The optical system 100 of the present invention will be described below. As shown in Figure 1, the optical system 100 of the present invention mainly consists of a light irradiation means 1 capable of irradiating light, a control unit 2 that controls the irradiation of the light irradiation means 1, and a heat dissipation unit 3 that dissipates heat from the light irradiation means 1 and the control unit 2.

[0018] Light irradiation means 1 is for irradiating light. Any light source capable of irradiating the light required for the purpose may be used. Examples of light irradiation means 1 include LEDs and VCSELs (Vertical Cavity Surface Emitting Lasers) that can be expected to produce high output with low power consumption. VCSELs include single-emitter VCSELs that have one light source capable of irradiating light in a direction perpendicular to the light-emitting surface, and multi-emitter VCSELs that have multiple light sources. Light irradiation means 1 may also consist of multiple LEDs or VCSELs.

[0019] The wavelength of the light emitted by the light source of the light irradiation means 1 can be appropriately determined depending on the purpose. For example, when used to measure blood flow, the light emitted by the light irradiation means 1 should be green light (electromagnetic waves with a wavelength of 500 to 565 nm), which is easily absorbed by red blood. When used to measure blood glucose levels, the light emitted by the light irradiation means 1 should be mid-infrared light (electromagnetic waves with a wavelength of 2.5 to 4 μm), which can measure the concentration of glucose in the blood.

[0020] The control unit 2 is electrically connected to the light irradiation means 1 and controls the irradiation of the light irradiation means 1. For example, the control unit 2 controls the ON / OFF state of the irradiation of the light irradiation means 1 and changes the light intensity. The control unit 2 has wiring 21 for receiving power from the power supply, wiring 22 for sending current to electrodes such as the anode and cathode of the light irradiation means, and wiring 23 for receiving electrical signals to determine the voltage of the current sent to the light irradiation means. It receives digital signals such as LVDC (Low Voltage Differential Signaling) and adjusts the voltage of the current sent from the power supply to the light irradiation means 1 based on these signals to control the irradiation of the light irradiation means 1. Any control unit 2 that can control the irradiation of the light irradiation means 1 is acceptable, but existing semiconductor elements can be used. A specific example of the control unit 2 is a VCSEL driver that electrically controls the light emission of a VCSEL.

[0021] The heat dissipation section 3 is connected to the light irradiation means 1 and the control unit 2 in a heat-conductive manner. This allows heat generated in the light irradiation means 1 and the control unit 2 to be dissipated by heat conduction, thereby suppressing the accumulation of heat. It is also preferable that the heat dissipation section 3 be connected to the housing 9 that covers the light irradiation means 1 and the control unit 2, and to the optical element 4 described later, in a heat-conductive manner. This allows heat generated in the light irradiation means 1 and the control unit 2 to be dissipated to the outside via heat conduction through the housing 9 and the optical element 4. The material of the heat dissipation section 3 should have a thermal conductivity at least higher than air, specifically, a thermal conductivity of 0.2 W / m·K or higher is preferable, preferably 0.5 W / m·K or higher, and even more preferably 1.0 W / m·K or higher. As such a material, a resin such as polydimethylsiloxane (PDMS) can be used. The heat dissipation section 3 must be transparent to light at least within the irradiation angle range of the light irradiation means 1. Therefore, it is preferable that the material of the heat dissipation section 3 be transparent to the light emitted by the light irradiation means 1.

[0022] Furthermore, the form of the heat dissipation section 3 can be any form as long as it can dissipate heat from the light irradiation means 1 and the control unit 2, but it is preferable that the contact area with the light irradiation means 1 and the control unit 2 is large in that it can dissipate heat efficiently.Therefore, as shown in Figure 1, it is preferable that the heat dissipation section 3 is sealed so that the surface of the light irradiation means 1 does not come into contact with the gas at all.It is also preferable that the heat dissipation section 3 is sealed so that the surface of the control unit 2 does not come into contact with the gas at all.In addition, the heat dissipation section 3 may have irregularities formed at the boundary with the light irradiation means 1 and the control unit 2, the housing 9 and the optical element 4 to increase the contact area.It is also possible to form the heat dissipation section 3 from different materials for each part.The heat dissipation section 3 can be manufactured in any way, for example, by conventionally known methods such as imprinting or injection molding.

[0023] Furthermore, the optical system 100 of the present invention may include an optical element 4 having an uneven shape 45 that exhibits an optical function with respect to the light emitted by the light irradiation means 1, as shown in Figures 2 and 3. The optical function refers to changing the light emitted by the light irradiation means 1 into a predetermined light distribution. Specific examples of the optical element 4 include, for example, one that transforms the light emitted by the light irradiation means 1 into a dot pattern, a line pattern, or uniform diffused light. The optical element 4 may have an air layer 7 between it and the surface 31 of the heat dissipation section 3, as shown in Figure 2, or it may be laminated on the surface 31 of the heat dissipation section 3, as shown in Figure 3. Here, the surface 31 means the surface from which the light emitted from the light irradiation means 1 is emitted from the heat dissipation section 3. When laminated on the surface 31 of the heat dissipation section 3, the heat generated in the light irradiation means 1 and the control unit 2 can be efficiently dissipated to the outside through the optical element 4 by thermal conduction.

[0024] Furthermore, the uneven shape 45 of the optical element 4 can be formed at the boundary with the air layer 7, as shown in Figure 2, or at the boundary of the resin layer, as shown in Figure 3. When the uneven shape 45 is formed at the boundary of the resin layer, the optical element 4 is mainly composed of a first resin layer 41 which is the side into which light from the light irradiation means 1 is incident and has a first refractive index, and a second resin layer 42 which is the side from which light is emitted and has a second refractive index higher than the first refractive index. In this case, as shown in Figure 3, the optical element 4 has the uneven shape 45 at the interface between the first resin layer 41 and the second resin layer 42. On the other hand, the heat dissipation part 3 may also serve as the first resin layer 41. In this case, as shown in Figure 4, the optical element 4 has the uneven shape 45 at the interface (surface 31) between the heat dissipation part 3 and the second resin layer 42. When the heat dissipation section 3 also serves as the first resin layer 41, the refractive index (first refractive index) of the heat dissipation section 3 must be lower than that of the second refractive index of the second resin layer.

[0025] The refractive index difference between the first and second refractive indices can be any value as long as it allows the uneven surface to function optically. Furthermore, in some cases, it is desirable to narrow the angle of light emitted from the lens of the optical element 4. To narrow the emission angle of the lens, one could consider reducing the lens sag. However, there are limits to the processing accuracy, making it difficult to reduce the lens sag beyond a certain point. In such cases, the refractive index difference between the first and second refractive indices may be reduced. This allows, for example, when the uneven surface is a lens shape, to reduce the irradiation angle while maintaining a large lens sag. The refractive index difference should be, for example, 0.4, preferably 0.2 or less. This makes it possible, for example, when the uneven surface is a lens shape, to reduce the irradiation angle to 30 degrees or less while maintaining a lens sag of 10 μm or more.

[0026] As the material of the optical element 4, any material may be used as long as it can transmit light of at least a predetermined wavelength λ. For example, a silicon-based resin, an epoxy-based resin, an acrylic-based resin, or the like can be used. Examples of the silicon-based resin include polydimethylsiloxane (PDMS). Further, glass can also be used as the material of the optical element 4. Further, the optical element 4 may be manufactured in any manner. For example, a conventionally known method such as an imprint method or injection molding may be used.

[0027] As a specific example of the optical element 4, for example, there is one in which lenses that transmit light of wavelength λ are periodically arranged. In this case, let m and n be natural numbers of 1 or more, and let the focal length due to the cross-sectional shape perpendicular to the y direction of the lens be f １ and the focal length due to the cross-sectional shape perpendicular to the x direction be f ２ , let the size of the pitch of the lens in the x direction be P １ and the size of the pitch in the y direction be P ２ . Then, if the distance L １ between the irradiation means and the first focal plane of the lens and the distance L ２ between the irradiation means and the second focal plane satisfy the following equations (1) and (2) , the light of wavelength λ irradiated by the light irradiation means 1 can be made into a dot pattern.

[0028] The first focal plane means a plane that is perpendicular to the optical axis (z direction) of the lens and is at the focal position due to the cross-sectional shape perpendicular to the y direction of the lens. The second focal plane means a plane that is perpendicular to the optical axis (z direction) of the lens and is at the focal position due to the cross-sectional shape perpendicular to the x direction of the lens. Further, the distances L １ and L ２ mean the distance (optical path length) that light travels in a vacuum within the same time when it travels in a medium. When the refractive index of the medium is N and the actual distance is L, they are represented by the product NL.

[0029] 1 Light irradiation means 2 Control unit 3 Heat dissipation unit 4 Optical element 9 Housing 31 Surface 41 First resin layer 42 Second resin layer 45 Concavo-convex shape 100 Optical system device

Claims

1. An optical system comprising: a light irradiation means capable of irradiating light; a control unit electrically connected to the light irradiation means and controlling the irradiation of the light irradiation means; and a heat dissipation unit in which at least the irradiation angle range of the light irradiation means is transparent to the light and is thermally conductively connected to the light irradiation means and the control unit.

2. The optical system according to claim 1, characterized in that the heat dissipation section is sealed so that the surface of the light irradiation means does not come into contact with a gas.

3. The optical system according to claim 1, characterized in that the heat dissipation section is sealed so that the surface of the control unit does not come into contact with gas.

4. The optical system according to any one of claims 1 to 3, characterized in that the heat dissipation part is made of a resin having a thermal conductivity of 0.2 W / m·K or more.

5. The optical system according to any one of claims 1 to 3, characterized in that the heat dissipation part is made of a resin having a thermal conductivity of 1.0 W / m·K or higher.

6. The optical system according to any one of claims 1 to 3, further comprising an optical element having an uneven shape that exhibits an optical function with respect to the light irradiated by the light irradiation means.

7. The optical system according to claim 6, characterized in that the optical element is laminated on the surface of the heat dissipation section.

8. The optical element consists of lenses that transmit light of wavelength λ arranged periodically, where m and n are natural numbers of 1 or more, and the focal length is determined by the cross-sectional shape of the lens perpendicular to the y-direction. １ The focal length is determined by the cross-sectional shape perpendicular to the x-direction, f ２ The size of the x-direction pitch of the lens is P １ The size of the pitch in the y direction is P ２ Therefore, the distance L between the irradiating portion and the first focal plane of the lens. １ , distance L from the second focal plane ２ However, see equations 1 and 2 below. The optical system according to claim 6, characterized in that it satisfies the following conditions.

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