Integrated projection system capable of automatically focusing

Abstract

The utility model relates to the technical field of optical systems, in particular to an integrated projection system capable of automatically focusing, which comprises a laser light source, a color wheel, a free-form surface reflector, a color separation film, a complementary metal oxide semiconductor (CMOS) image sensor, a lens and a digital micro-mirror device. The laser light source is arranged below the second condensing lens assembly, the free-form surface reflector is obliquely arranged above the first condensing lens assembly and located above the central axis of the horizontally-arranged lens, and a color separation piece and a digital micro-mirror device are sequentially arranged on the lens central axis of the side, away from the lens, of the free-form surface reflector. The color separation film is obliquely arranged, and a CMOS image sensor is arranged above the color separation film. In the system, the RGB light is used for illumination projection, the near-infrared light is used for supplementary lighting, and the lens is used for imaging the light in the near-infrared band for feedback adjustment focusing, so that the projection and feedback focusing functions are integrated.

Description

Technical Field

[0001] The utility model relates to the technical field of optical systems, in particular to an integrated projection system with automatic focusing function. Background Art

[0002] A vehicle-mounted projection headlamp is a kind of lamp that uses DLP (Digital Light Processing) technology to project pixel points onto the road surface through a DMD (Digital Micro-mirror Device) device. A single lamp can achieve high-precision ADB (Adaptive Driving Beam) lighting with 900,000 to 1.3 million pixels, or use its pixelated projection function to realize functions such as video playback and symbol display.

[0003] In existing vehicle-mounted projection headlamps, generally, focusing is carried out in advance at a fixed distance and no focusing is performed during use; or image recognition is performed using a vehicle-mounted camera, and then a motor is controlled to automatically focus the lens. When focusing at a fixed distance in advance, the pattern is only clear within a single depth of field range. However, the application range of vehicle-mounted projection headlamps covers from near distance to infinity, so there must be positions where the projection is not clear. When using a vehicle-mounted camera for image recognition and controlling focusing, higher requirements are put forward for the resolution, field of view, and installation position of the vehicle-mounted camera. Usually, the vehicle-mounted camera uses a projection lens with a large field of view and a small focal length, and its imaging ability for distant targets is limited, and it cannot well meet the requirements of long-distance focusing. Moreover, using a camera for recognition and feedback focusing requires cooperation between multiple modules, with low transmission efficiency and high space occupation. Summary of the Invention

[0004] The technical problem to be solved by the utility model is: to provide an integrated projection system with automatic focusing function in order to solve the problems existing in the prior art in the above-mentioned background art.

[0005] The technical solution adopted by the utility model to solve its technical problem is: an integrated projection system with automatic focusing function, which includes a laser light source, a color wheel, a free-form surface reflector, a dichroic filter, a CMOS image sensor, a lens, and a digital micromirror device. A first condenser lens assembly and a second condenser lens assembly are symmetrically arranged above and below the edge of the color wheel. The laser light source is arranged below the second condenser lens assembly. The free-form surface reflector is obliquely arranged above the first condenser lens assembly and is located above the central axis of the horizontally arranged lens. A dichroic filter and a digital micromirror device are successively arranged on the central axis of the lens on the side of the free-form surface reflector away from the lens. The dichroic filter is obliquely arranged, and a CMOS image sensor is arranged above it.

[0006] Further, the included angle between the dichroic filter and the horizontal direction is 35° to 55°. With such a setting, the visible light optical path and the near-infrared optical path can be separated, and the functions of projection and imaging focusing are integrated into one.

[0007] Preferably, the included angle between the dichroic filter and the horizontal direction is 45°.

[0008] Further, a dichroic film is provided on the upper surface of the dichroic filter. With such a setting, the transmittance and reflectance in the near-infrared band are 50% ± 5%.

[0009] Further, the included angle between the free-form surface mirror and the horizontal direction is 56° to 66°. With such a setting, the near-infrared beam in the illumination beam will not enter the CMOS image sensor to introduce interference when reflected by the dichroic filter.

[0010] Further, the first condenser lens assembly and the second condenser lens assembly have the same structure, and both include a first condenser lens and a second condenser lens, and the first condenser lens is arranged close to the color wheel.

[0011] Further, the color wheel is mounted on the output shaft of a motor. An impeller is connected to the middle of the color wheel through a rotating shaft, and the rotating shaft is a hollow shaft, and the hollow shaft is sleeved on the output shaft of the motor.

[0012] Further, a fluorescent region is provided on the outer edge of the color wheel, and the fluorescent region is composed of an R fluorescent region, a G fluorescent region, a B fluorescent region, and a NIR region arranged in sequence. With such a setting, RGB light beams and near-infrared light beams can be generated by using the method of laser-excited fluorescence, which are respectively used for projection and supplementary light illumination.

[0013] Advantages of the present utility model:

[0014] A fluorescent region is provided on the outer edge of the color wheel, and the fluorescent region is divided into four regions of RGB and NIR, and four bands of light of RGB and near-infrared are excited. Among them, the RGB light is used for illumination projection; the near-infrared is used for supplementary light illumination, and at the same time, the lens images the light in the near-infrared band for feedback adjustment of focusing, realizing the integration of the functions of projection and feedback focusing;

[0015] The camera and the projector share the same lens, and the projection optical path and the camera optical path are distinguished by a dichroic filter, reducing the number of modules and improving the space utilization rate;

[0016] By setting different back foci for the near-infrared imaging optical path and the projection optical path to make up for the defocus amounts of different bands, when the near-infrared imaging is focused clearly, the white light projection is exactly in the clear position. Since the camera and the projection optical paths are coaxial, the center of the field of view is always imaged during focusing, and the focusing requirements at various distances and angles can be adapted. Description of the Drawings

[0017] The present utility model will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] Figure 1 is a schematic plan view of the present utility model.

[0019] Figure 2 is a schematic three-dimensional view of the present utility model.

[0020] Figure 3 is a schematic plan view of the color wheel in the present utility model.

[0021] Figure 4 is a schematic three-dimensional view of the color wheel in the present utility model.

[0022] Figure 5 is a schematic diagram of the principle of the present utility model.

[0023] Figure 6 is a schematic diagram of the optical path of the present utility model.

[0024] Figure 7 is the defocus curve under near-infrared light when the present utility model is actually in use.

[0025] In the figure: 1. Laser light source; 2. First condenser lens; 3. Second condenser lens; 4. Motor; 5. Color wheel; 6. Free-form surface mirror; 7. Dichroic filter, 8. Digital micromirror device; 9. Lens; 10. CMOS image sensor; 20. First condenser lens assembly; 30. Second condenser lens assembly; 501. R fluorescence region; 502. G fluorescence region; 503. B fluorescence region; 504. NIR region; 505. Impeller. Specific embodiments

[0026] The present utility model will now be described in further detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present utility model in a schematic manner, so they only show the components related to the present utility model.

[0027] Such as Figure 1 and Figure 2As shown in the figure, an integrated projection system with automatic focusing includes a laser light source 1, a color wheel 5, a free-form surface mirror 6, a dichroic filter 7, a CMOS image sensor 10, a lens 9, and a digital micromirror device 8. A first condenser lens assembly 20 and a second condenser lens assembly 30 are symmetrically arranged above and below the edge of the color wheel 5. The laser light source 1 is arranged below the second condenser lens assembly 30. The free-form surface mirror 6 is inclined and arranged above the first condenser lens assembly 20 and is located above the central axis of the horizontally arranged lens 9. A dichroic filter 7 and a digital micromirror device (DMD) 8 are successively arranged on the central axis of the lens 9 on the side of the free-form surface mirror 6 away from the lens 9. The dichroic filter 7 is inclined, and a dichroic film is provided on the upper surface of the dichroic filter 7. A CMOS image sensor 10 is provided above the dichroic filter 7.

[0028] Among them, the first condenser lens assembly 20 and the second condenser lens assembly 30 have the same structure, and both include a first condenser lens 2 and a second condenser lens 3. The first condenser lens 2 is arranged close to the color wheel 5. According to needs, the first condenser lens assembly 20 and the second condenser lens assembly 30 can adopt other combinations of condenser lenses with different numbers and distributions. The digital micromirror device (DMD) is an advanced spatial light modulator, which has a wide range of applications in the field of spectral imaging technology. The CMOS image sensor is a device that converts an optical image into a digital signal. Its working principle is to use a photosensitive unit array to capture light, convert the optical signal into an electrical signal, and then convert these electrical signals into digital signals through an analog-to-digital converter (ADC), and finally perform image processing and output.

[0029] As Figure 3 and Figure 4 shown in the figure, the color wheel 5 is installed on the output shaft of a motor 4. An impeller 505 is connected to the middle of the color wheel 5 through a rotating shaft. The rotating shaft is a hollow shaft, and the hollow shaft is sleeved on the output shaft of the motor 4. When the motor 4 drives the color wheel 5 to rotate, air flow can be generated to assist heat dissipation. A fluorescent area is arranged on the outer edge of the color wheel 5. The fluorescent area is composed of an R fluorescent area 501, a G fluorescent area 502, a B fluorescent area 503, and an NIR (Near Infrared) area 504 arranged in sequence. When irradiated by the laser light source 1, RGB beams and near-infrared beams will be respectively excited.

[0030] As Figure 5As shown in the figure, the working principle of the autofocus integrated projection system of this embodiment is as follows: After the RGB light and near-infrared light illuminate the digital micromirror device 8, the RGB light forms a pattern according to the on / off states of the micromirror array of the digital micromirror device 8 and is projected onto the ground through the lens 9; the near-infrared light is reflected by the fully open state of the digital micromirror device 8 and illuminates the ground through the projection lens 9 for supplementary lighting. Since the near-infrared light is invisible to the human eye, it will not affect the visual effect of normal projection. The near-infrared light reflected by the ground structure is imaged on the surface of the CMOS image sensor 10 through the lens 9 to form an image. According to the clarity of the image and the corresponding focusing algorithm, the lens 9 is controlled to autofocus so that the lens 9 is located at the optimal focal length position for projection and imaging.

[0031] As Figure 6 shown in the figure, the working process of the autofocus integrated projection system of this embodiment is as follows: The laser emitted by the laser light source 1 is focused by the condenser lens 1 and the condenser lens 2 of the second condenser lens assembly 30 onto the fluorescent region of the color wheel 5. The motor 4 drives the color wheel 5 to rotate, so that the laser respectively excites each fluorescent region (R fluorescent region 501, G fluorescent region 502, B fluorescent region 503, and NIR region 504) to generate RGB light and near-infrared light ( Figure 6 represented by the solid line in the figure). The excited light is first collimated by the condenser lens 1 and the condenser lens 2 of the first condenser lens assembly 20, and then shaped and focused onto the digital micromirror device 8 through the free-form surface mirror 6. The dichroic filter 7 between the free-form surface mirror 6 and the digital micromirror device 8 has a dichroic film coated on its upper surface, so that the transmittance in the visible light band is greater than 99%, and the transmittance and reflectance in the near-infrared band are both 50%, thereby realizing the separation of the visible light optical path and the near-infrared optical path ( Figure 6 represented by the dashed line in the figure for the ineffective near-infrared light). When the RGB light beam illuminates the digital micromirror device 8, the on / off states of the digital micromirror device 8 are controlled according to the input image information, and the reflected light beam is projected onto the ground through the lens 9; when the near-infrared light beam irradiates the digital micromirror device 8, it remains in the fully open state and forms a rectangular light spot to illuminate the ground through the lens 9. The effective near-infrared light reflected by the ground structure ( Figure 6 represented by the bold solid line in the figure) is imaged through the lens 9. The optical path of the effective near-infrared light is deflected at the dichroic filter 7 and enters the CMOS image sensor 10. According to the formed image and the focusing algorithm, the lens 9 is controlled to perform a focusing movement to achieve the focusing operation. Since there is a certain defocus amount for the optical paths of different wavelengths. As Figure 7 shown in the figure, when the visible light is clear, it is the defocus curve under the near-infrared light, and its defocus amount is 0.26 mm. Therefore, the back focus in the near-infrared optical path (i.e., the optical path distance between the CMOS image sensor 10 and the lens 9) is 0.26 mm farther than the back focus in the visible light optical path (i.e., the optical path distance between the CMOS image sensor 10 and the lens 9). At this time, the near-infrared image is in focus, and the visible light projection will also be clear at the same time.

[0032] In order to reduce the interference of stray light on imaging, the included angle between the dichroic filter 7 and the horizontal direction is within 45° ± 10°, preferably the included angle between the dichroic filter 7 and the horizontal direction is 45°. The reflection direction of the imaging beam deflects towards the free-form surface mirror 6, and the included angle between the free-form surface mirror 6 and the horizontal direction is 56° to 66°. At this time, the illumination beam is reflected at a small angle on the dichroic filter 7 and will not enter the CMOS image sensor 10 to cause interference.

[0033] Inspired by the above ideal embodiments of the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An integrated projection system capable of automatic focusing, characterized in that: The invention comprises a laser light source (1), a color wheel (5), a free-form surface reflector (6), a color separation plate (7), a CMOS image sensor (10), a lens (9) and a digital micromirror device (8); a first condensing lens assembly (20) and a second condensing lens assembly (30) are symmetrically arranged above and below the edge of the color wheel (5); the laser light source (1) is arranged below the second condensing lens assembly (30); the free-form surface reflector (6) is arranged obliquely above the first condensing lens assembly (20) and above the central axis of the horizontally arranged lens (9); a color separation plate (7) and a digital micromirror device (8) are arranged in sequence on the central axis of the lens (9) on the side of the free-form surface reflector (6) away from the lens (9); the color separation plate (7) is arranged obliquely and a CMOS image sensor (10) is arranged above it.

2. The integrated projection system with automatic focusing according to claim 1, characterized in that: The angle between the color separation sheet (7) and the horizontal direction is 35° to 55°.

3. The integrated projection system with automatic focusing according to claim 2, characterized in that: The angle between the color separation sheet (7) and the horizontal direction is 45°.

4. The integrated projection system with automatic focusing according to claim 1, 2 or 3, characterized in that: A layer of dichroic film is provided on the upper surface of the dichroic sheet (7).

5. The integrated projection system with automatic focusing according to claim 1, characterized in that: The angle between the free-form surface reflector (6) and the horizontal direction is 56° to 66°.

6. The integrated projection system with automatic focusing according to claim 1, characterized in that: The first condenser lens assembly (20) and the second condenser lens assembly (30) have the same structure, both comprising a condenser lens 1 (2) and a condenser lens 2 (3), wherein the condenser lens 1 (2) is arranged close to the color wheel (5).

7. The integrated projection system with automatic focusing according to claim 1, characterized in that: The color wheel (5) is mounted on an output shaft of a motor (4); the center of the color wheel (5) is connected to an impeller (505) via a rotating shaft; the rotating shaft is a hollow shaft, and the hollow shaft is sleeved on the output shaft of the motor (4).

8. The integrated projection system with automatic focusing according to claim 1 or 7, characterized in that: The outer edge of the color wheel (5) is provided with a circle of fluorescent areas, and the fluorescent areas are composed of an R fluorescent area (501), a G fluorescent area (502), a B fluorescent area (503) and an NIR area (504) which are arranged in sequence.

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