Optical Sensors

Abstract

The invention relates to an optical sensor (25), comprising a first light detector (30), a second light detector (35), an optical path (40) and an evaluation unit (10), wherein the first light detector (30) is configured to detect light in the infrared wavelength range. The first light detector (30) and the second light detector (35) are each a CCD sensor, wherein the light sensitivity of the CCD sensor of the first light detector (30) and the light sensitivity of the CCD sensor of the second light detector (35) differ in a predefined wavelength range. The first light detector (30) and the second light detector (35) also have pixels (50) arranged in a row, which are arranged adjacent to each other so that a first longitudinal side of the first light detector (30) adjoins a first longitudinal side of the second light detector (35), and the first light detector (30) and the second light detector are additionally configured to receive light via the optical path (40). The first light detector (30) is further configured to generate a first measurement signal from an electric charge, and the second light detector (35) is further configured to generate a second measurement signal from an electric charge. The evaluation unit (10) is configured to receive the first measurement signal with a first sampling frequency and the second measurement signal with a second sampling frequency and to combine the first measurement signal and the second measurement signal into an output signal.

Description

Technical Field

[0001] The present invention relates to an optical sensor and in particular to an optical sensor based on CCD technology. Background Art

[0002] Optical sensors based on different technologies, such as CCD detectors, CMOS detectors, SPAD detectors, etc., are known from the prior art, which can be used to detect electromagnetic radiation. CCD detectors and CMOS detectors are usually used for RGB image detection in camera systems, while SPAD detectors are usually used in conjunction with LiDAR sensors. Furthermore, vehicles are known from the prior art, which perform environmental detection based on cameras and / or based on LiDAR systems.

[0003] DE102009060392A1 describes a sensor device for being arranged on the inner side of a motor vehicle window pane, the sensor device having at least one sensor for receiving and / or transmitting electromagnetic radiation, the sensor device comprising a first housing module for accommodating a computing unit and a second housing module for accommodating at least one sensor. In a preferred embodiment, a laser radar sensor and a camera are arranged in the second housing module, the laser radar sensor consisting of a laser transmitter and a laser receiver. The laser transmitter can preferably be a pulsed laser, which consists of a predetermined number of laser diodes, which are connected to each other in a stack.

[0004] WO002001017838A1 describes a method for monitoring hazardous areas for dangerous and / or hazardous objects by means of an image recording device, wherein the image recording is performed based on multiple sensors in order to increase reliability and persuasiveness. An exemplary embodiment of the present invention is based on a combination of the advantages of automatic stereo analysis of stereo image pairs and spatial data acquisition by means of 3D laser measurement technology.

[0005] US2016240579A1 describes an optical sensor, which includes a pixel array, which is composed of a plurality of pixels for detecting visible light and a plurality of pixels for detecting infrared light, wherein the pixels for infrared light detection particularly detect TOF (time of flight, English: Time of Flight) information of the emitted infrared light. In a preferred embodiment of the sensor according to the present invention, the corresponding sensor pixels are interlaced on a single chip (Die) and have separate circuits for reading out the corresponding sensor information.

[0006] The object of the present invention is to provide an optical sensor which is configured to enable depth detection based on a laser radar and color detection based on an RGB based on a combined CCD sensor. Summary of the invention

[0007] The present invention proposes an optical sensor, which includes a first light detector, a second light detector, an optical path and an analysis unit. The first light detector is configured to detect light in an infrared wavelength range. The light in the infrared wavelength range can preferably be generated by an infrared laser source of the optical sensor and radiated into the environment of the optical sensor. Therefore, the portion of the infrared laser light reflected and / or scattered by the environment to the first light detector can be used for active measurement performed by the first light detector. The light in the infrared wavelength range detected by the first light detector and / or by the second light detector can further preferably be a pulsed laser and / or a "continuous wave" laser.

[0008] The first photodetector and the second photodetector are each a CCD (charge-coupled device) sensor, wherein the light sensitivity of the CCD sensor of the first photodetector differs from the light sensitivity of the CCD sensor of the second photodetector in a predefined wavelength range. Therefore, in the case that the first photodetector and the second photodetector are both designed for essentially the same wavelength range (for example, both are designed as infrared photodetectors), then according to the invention, one of the two photodetectors has a lower sensitivity in this wavelength range. In the case that the first photodetector and the second photodetector are designed for different wavelength ranges (for example, an infrared photodetector and an RGB photodetector for visible light), then according to the invention, the first photodetector has a lower light sensitivity (or even no light sensitivity) for the wavelength range of the second photodetector, and vice versa. In addition, the first photodetector and the second photodetector each include pixels arranged in a column, which are arranged adjacent to each other in such a way that a first longitudinal side of the first photodetector adjoins a first longitudinal side of the second photodetector. The respective pixel columns of the first photodetector and the second photodetector can each include a one-dimensional or two-dimensional arrangement of pixels. Due to the local proximity of the pixel columns of the first photodetector and the second photodetector, the two photodetectors are arranged to simultaneously receive light from the environment of the optical sensor via a commonly used optical path. The optical sensor is arranged in conjunction with the first photodetector to generate a first measurement signal from the charge generated when light is incident on the first photodetector, and in conjunction with the second photodetector to generate a second measurement signal from the charge generated when light is incident on the second photodetector.

[0009] The analysis unit is configured to receive a first measurement signal with a first sampling frequency and a second measurement signal with a second sampling frequency, and to combine the first measurement signal and the second measurement signal into an output signal. The analysis unit can be configured, for example, as an ASIC, an FPGA, a processor, a digital signal processor, a microcontroller or the like. The output signal can preferably be a total signal generated by the first measurement signal and the second measurement signal. Alternatively or additionally, the output signal can also include the first measurement signal and the second measurement signal as separate measurement signals. In addition, the first sampling frequency and the second sampling frequency can be the same or different frequencies. Preferably, the analysis unit according to the present invention can be connected to the optical sensor by information technology through an A / D converter, which is configured to convert the charge quantity generated by the first photodetector and the second photodetector into a corresponding digital signal. This can be done by an A / D converter used in common by the first and second photodetectors or by a corresponding separate A / D converter for the corresponding photodetector. In addition, the A / D converter can be a component of the optical sensor itself or a component of the analysis unit. In addition, the analysis unit can be a component of the optical sensor. Advantageously, the corresponding A / D converter can also be connected upstream of the signal amplifier.

[0010] An optical path can be understood as a light entry path between entry openings (e.g. in a housing) of the optical sensor to the respective sensor pixels of the first and second light detectors. Preferably, optical elements for optimally matching (e.g. focusing, deflecting, splitting, etc.) the light entering the optical sensor may be present in the optical path, such as lenses, lens systems, mirrors, etc.

[0011] The dependent claims reveal preferred embodiments of the invention.

[0012] In an advantageous embodiment of the invention, the optical sensor is a rotary scanner and / or the evaluation unit is configured to generate a corresponding light detector-dependent overall image of the environment of the optical sensor and / or a sensor-dependent overall image of the environment of the optical sensor from a plurality of first measurement signals and a plurality of second measurement signals of the corresponding scanning process and output it in the form of an output signal. The optical sensor according to the invention is configured to sequentially sample the environment of the optical sensor by means of a rotary scanning movement of the rotary scanner known from the prior art. The evaluation unit can be configured, for example, based on a computer program executed by the evaluation unit, to combine the corresponding individual images constructed in a column shape into an overall image of the environment.

[0013] In another advantageous embodiment of the present invention, the optical sensor additionally comprises a first transfer register and / or a second transfer register, wherein the first transfer register and / or the second transfer register respectively comprise at least one pixel column, which is adjacent to the second longitudinal side of the first photodetector and / or adjacent to the second longitudinal side of the second photodetector. In addition, the first transfer register and the second transfer register are configured to buffer the charge generated by the first photodetector and / or the second photodetector and sequentially output the charge to the clock-driven evaluation unit. According to the CCD sensor principle in the prior art, the corresponding transfer register is located in the light-proof area of ​​the optical sensor, so that the light incident through the optical path has no effect on the transfer register. In connection with the corresponding application of the optical sensor according to the present invention, it can be advantageous to set only the first or only the second transfer register or respectively set two transfer registers in order to transport the charge generated by the optical sensor outward from the area of ​​the corresponding photodetector surface for a downstream readout process.

[0014] In another advantageous embodiment of the invention, the first transfer register and the second transfer register have the same or different numbers of pixel columns. The number of pixel columns of the first transfer register and / or the second transfer register is preferably oriented to the salient features of the light to be detected and / or the corresponding sampling frequency of the corresponding light detector. In the case of using pulsed laser light to illuminate the environment of the optical sensor, the number of pixel columns for the transfer registers respectively associated with the infrared light reception can preferably be selected in such a way that at least one pulse width of the pulsed laser light can be completely retained in the corresponding transfer register.

[0015] In another advantageous embodiment of the invention, the second light detector is provided for detecting light in the visible wavelength range, and the evaluation unit is additionally provided for generating an output signal based on the first measurement signal and based on the second measurement signal, which output signal includes not only depth information about the environment detected by the optical sensor but also color information about the environment detected by the optical sensor. Preferably, the measurement of visible light by the second light detector is a passive measurement, but it is also conceivable that by additionally illuminating the environment using a light source for the visible wavelength range, an active measurement can also be achieved by the second light detector.

[0016] In another advantageous embodiment of the invention, the second photodetector is provided for detecting light in the infrared wavelength range, and the evaluation unit is additionally provided for generating an output signal based on the first measurement signal and the second measurement signal, which output signal comprises an extended dynamic range with respect to the first measurement signal or with respect to the second measurement signal. Due to the different sensitivities of the first photodetector and the second photodetector according to the invention, the evaluation unit can, for example, use less exposed areas of the environment of the corresponding measurement signal from the photodetector that is more sensitive to light, while the evaluation unit can use more exposed areas of the environment of the corresponding measurement signal from the photodetector that is less sensitive to light. Suitable algorithms for merging the two measurement signals can, for example, be guided by algorithms known from the prior art for generating so-called HDR (“High Dynamic Range”) images.

[0017] In another advantageous configuration of the present invention, the first photodetector and the second photodetector respectively have the same or different semiconductor materials and / or exposure times and / or orientations with respect to the optical path and / or attenuation filters (e.g., gray filters) and / or sampling frequencies and / or resolutions and / or pixel sizes. In particular, due to the deviations between one or more of the above-mentioned technical characteristics of the respective photodetectors, a suitable extension of the dynamic range can be achieved when using two infrared photodetectors. In addition, the different technical characteristics between the two photodetectors can be utilized in order to advantageously configure the above-mentioned combination of infrared photodetectors and RGB photodetectors in a specific application. In the case of an infrared / RGB photodetector combination, it can be particularly advantageous to orient the first photodetector (i.e., the infrared photodetector) optimally on the optical path (i.e., perpendicular to the optical path) so that the maximum light efficiency for the photodetector can be achieved, while the RGB photodetector can have a small deviation associated with the optimal orientation with respect to the optical path.

[0018] In another advantageous configuration of the present invention, the first photodetector and the second photodetector can be constructed together on the same substrate or can be constructed on separate substrates. In addition, the first photodetector and / or the second photodetector can be manufactured based on silicon or indium phosphide or gallium arsenide, respectively. In the case of configuring the first photodetector and the second photodetector based on the same semiconductor material, silicon can be used in particular, because silicon is suitable not only for detection in the infrared wavelength range, but also for detection in the visible wavelength range. By using the same semiconductor material, the production steps and the manufacturing costs associated therewith can be reduced. In addition, this can also achieve higher integration and thus a reduction in the size of the optical sensor.

[0019] The simultaneous RGB image acquisition and distance measurement based on the CCD lidar system proposed here can primarily achieve an optimized time synchronization of color information and depth information. In addition, the adjustment and calibration costs for different light detectors can be omitted because the light to be detected can be received via the same optical path. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] Figure 1 shows a schematic overview of an optical sensor according to the present invention;

[0022] Figure 2 A first embodiment of a light detector unit of an optical sensor according to the present invention is shown;

[0023] Figure 3 A second embodiment of the light detector unit of the optical sensor according to the present invention is shown;

[0024] Figure 4 A third embodiment of a light detector unit of an optical sensor according to the invention is shown. DETAILED DESCRIPTION

[0025] Figure 1The schematic overview of an optical sensor 25 according to the invention, which is a rotary scanner in this case, is shown. The optical sensor 25 comprises a photodetector unit 45, which comprises a first photodetector 30 and a second photodetector 35. The first photodetector 30 is a photodetector for the infrared wavelength range in this case, while the second photodetector 35 is a photodetector for the visible wavelength range in this case. The first photodetector 30 and the second photodetector 35 each comprise a one-dimensional pixel column 55, which is respectively composed of a plurality of detector pixels 50. The pixel column 55 of the first photodetector 30 is oriented in relation to the optical path 40 (light entry path) of the optical sensor 25 in such a way that the surface normal of the pixel plate 55 of the first photodetector 30 runs parallel to the optical path 40. The optical path 40 comprises a lens system 70 in this case, which focuses the light entering the optical sensor 25. A first transfer register 60 and a second transfer register 65 are arranged adjacent to the respective photodetectors 30, 35, which are provided for conveying the charge generated by the photodetectors 30, 35 when light is incident from the photosensitive regions of the photodetectors 30, 35 outwardly. The image information represented by the charge is conveyed in this way from the central region of the photodetector unit 45 to the respective sides of the photodetector unit 45. There, the charge quantity is converted into a first and a second digital measurement signal by a combination of a corresponding (not shown) signal amplifier and an A / D converter and transmitted to the evaluation unit 10 according to the invention, which is connected to the A / D converter in an information technology manner. The evaluation unit 10 stores the received measurement signal in a memory unit 20, which is connected to the evaluation unit 10 in an information technology manner. After the environment of the optical sensor 25 has been completely sampled, the evaluation unit 10 calculates a total image of the environment in the form of a 3D color image based on the measurement signal stored in the memory unit 20.

[0026] Figure 2 A first embodiment of a light detector unit 45 of an optical sensor in the form of a rotary scanner according to the invention is shown. The detector unit 45 comprises a first light detector 30 for detecting light in the infrared wavelength range, which is here a lidar sensor, and a second light detector 35 (RGB sensor) for detecting light in the visible wavelength range. Figure 1As in the example, an overall image of the environment of the optical sensor is also generated here by rotating the corresponding pixel columns 55 and by combining the corresponding detected column images. In order to take into account the different flight times required for different measurements, in the case of a lidar sensor, the electrons generated by the incident light are moved away to the left via a first transfer register 60 (first transfer direction 62). This enables correspondingly high sampling frequencies, such as those required for sampling lidar pulses in the case of the TOF ("Time of Flight" in English: Time of Flight) measurement principle. For RGB sensors, due to the integration-based measurement principle (imager principle), relatively long integration times are required within a single pixel 50, and therefore lower sampling frequencies are required. In the case of an RGB sensor, the electrons generated by the incident light are moved away to the right via a second transfer register 65 (second transfer direction 67). In Figure 1 FIG. 4 shows an embodiment with different pixel sizes between the first light detector 30 and the second light detector 35. Therefore, it is possible to provide complete color information for each "lidar pixel" 50.

[0027] Figure 3 A second embodiment of a detector unit 45 of an optical sensor in the form of a rotary scanner according to the invention is shown. The detector unit 45 comprises a first light detector 30 and a second light detector 35, each of which is provided for detecting light in the infrared wavelength range. Although the second embodiment provides the same pixel size of the corresponding detector pixels 50 in the corresponding pixel columns 55 of the first light detector 30 and the second light detector 35, the corresponding light detectors 30, 35 are operated at different sampling frequencies. As a result, different lengths of integration times are generated in the detector pixels 50 of the corresponding light detectors 30, 35, which result in different sensitivities of the corresponding light detectors 30, 35. The electrons released in the light detectors 30, 35 by the incident light are guided via a first transfer register 60 in a first transfer direction 62 and via a second transfer register 65 in a second transfer direction 67 with a corresponding light detector-specific clock to an A / D converter 80, which then generates a first digital measurement signal for the first light detector 30 and a second digital measurement signal for the second light detector 35. Based on the two measurement signals, an evaluation unit according to the invention (not shown) can then calculate an overall image of the surroundings of optical sensor 25 with an extended dynamic range.

[0028] Figure 3A third embodiment of a detector unit 45 of an optical sensor in the form of a rotary scanner according to the invention is shown. The detector unit 45 comprises a first light detector 30 and a second light detector 35, which are each provided for detecting light in the infrared wavelength range. Figure 2 In contrast, the second photodetector 35 has four times as many detector pixels 50 in the pixel column 55 as the first photodetector 30. Accordingly, the number of pixels of the respectively corresponding transfer registers 60, 65 is also different, which transfer the charges generated in the first photodetector 30 and the second photodetector 35 by the incident light to the outside in the direction of the corresponding transfer directions 62, 67. In this way, different sensitivities of the respective photodetectors 30, 35 can also be generated, because due to the different areas of the detector pixels 50 more (larger pixels) or fewer (smaller pixels) photons are received in the same time period, so that one of the measurement signals generated thereby is suitable for detecting bright objects and the corresponding other measurement signal generated thereby is suitable for detecting dim objects. The evaluation unit according to the invention (not shown) then calculates the two measurement signals into a total image with an increased dynamic range.

Claims

1. An optical sensor (25), comprising: a first light detector (30), a second light detector (35), an optical path (40), and An analysis and processing unit (10), in, The first light detector (30) is configured to detect light in an infrared wavelength range, and the first light detector (30) and the second light detector (35) are respectively CCD sensors, wherein the photosensitivity of the CCD sensor of the first light detector (30) is different from the photosensitivity of the CCD sensor of the second light detector (35) in a predefined wavelength range, Each of the pixels (50) is arranged in a row and is arranged adjacent to one another in such a way that a first longitudinal side of the first light detector (30) adjoins a first longitudinal side of the second light detector (35), are respectively configured to receive light through the optical path (40), The optical sensor is configured in combination with the first light detector (30) to generate a first measurement signal from the charge, and in combination with the second light detector (35) to generate a second measurement signal from the charge, The analysis unit (10) is configured to receive the first measurement signal with a first sampling frequency and the second measurement signal with a second sampling frequency, and to combine the first measurement signal and the second measurement signal into an output signal. Wherein, the optical sensor further comprises: a first transfer register (60), and / or The second transfer register (65), The first transfer register (60) and / or the second transfer register (65) respectively include at least one pixel column (55), the pixel column being adjacent to the second longitudinal side of the first light detector (30) and / or adjacent to the second longitudinal side of the second light detector (35), The device is provided for buffering charges generated by the first photodetector (30) and / or the second photodetector (35) and sequentially outputting the charges to the evaluation unit (10) in a clocked manner.

2. The optical sensor (25) according to claim 1, wherein: The optical sensor (25) is a rotary scanner, and / or The evaluation unit (10) is configured to generate a corresponding light detector-dependent overall image of the environment of the optical sensor (25) from a plurality of first measurement signals and a plurality of second measurement signals of a corresponding scanning process, and / or The total image associated with the sensor, And the corresponding total image related to the light detector and / or the total image related to the sensor is output in the form of the output signal.

3. The optical sensor (25) according to claim 1, wherein: The first transfer register (60) and the second transfer register (65) have the same or different numbers of pixel columns (55). The number of the corresponding pixel columns (55) of the first transfer register (60) and / or the second transfer register (65) is corresponding salient features of the light to be detected, and / or The corresponding sampling frequencies of the corresponding photodetectors (30, 35) Guided by.

4. The optical sensor (25) according to any one of claims 1 to 3, wherein: The second light detector (35) is configured to detect light in a visible wavelength range, and the analysis unit (10) is configured to generate an output signal based on the first measurement signal and the second measurement signal, wherein the output signal includes not only depth information about the environment detected by the optical sensor (25) but also color information about the environment detected by the optical sensor (25).

5. The optical sensor (25) according to any one of claims 1 to 3, wherein: The second light detector (35) is configured to detect light in the infrared wavelength range, and the evaluation unit (10) is configured to generate an output signal based on the first measurement signal and the second measurement signal, the output signal comprising an extended dynamic range with respect to the first measurement signal or with respect to the second measurement signal.

6. The optical sensor (25) according to any one of claims 1 to 3, wherein: The first photodetector (30) and the second photodetector (35) respectively have the same or different semiconductor materials, and / or exposure time, and / or with respect to the orientation of the optical path (40), and / or Attenuation filters, and / or sampling frequency, and / or resolution, and / or Pixel size.

7. The optical sensor (25) according to any one of claims 1 to 3, wherein: The light in the infrared wavelength range detected by the first light detector (30) and / or the second light detector (35) is emitted by the optical sensor (25) into the environment of the optical sensor (25). Pulsed, and / or Continuous Wave laser.

8. The optical sensor (25) according to any one of claims 1 to 3, wherein: The first light detector (30) and the second light detector (35) co-constructed on the same substrate, or constructed on separate substrates.

9. The optical sensor (25) according to any one of claims 1 to 3, wherein: The first light detector (30) and / or the second light detector (35) are respectively based on Silicon, or Made of indium phosphide, or gallium arsenide.

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