JP2024000938A - Light detection device and ranging system - Google Patents

Abstract

To provide a light detection device capable of allowing easy semiconductor integration and achieving low power consumption and excellent ranging accuracy.SOLUTION: The light detection device comprises: a receiving part receiving a first optical signal including a plurality of wavelength bands; a plurality of pixels performing convolutional calculation by auto-correlation or cross correlation on the basis of the first optical signal and a second optical signal to generate a pixel signal; an analog-digital converter analog-digital converting the pixel signal to generate a digital signal; and a Fourier transformation processing part performing Fourier transformation processing on the digital signal.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a photodetection device and a ranging system.

FMCW (Frequency Modulated Continuous Wave) type radar and ranging sensors have been proposed (see Patent Document 1). The FMCW distance measuring sensor is a type of ToF (Time of Flight) method, and measures distance by converting distance into frequency.

In an FMCW distance measuring sensor, a light source emits an optical signal with a continuously changing frequency, and in a time domain where the frequency difference between the frequency of this optical signal and the frequency of reflected light from an object is constant, The amount of delay in reflected light is detected, and the distance to the object is estimated based on the detected amount of delay.

Japanese Patent Application Publication No. 2022-61809

FMCW distance measurement sensors are characterized by excellent distance measurement accuracy over long distances and low power consumption. It is common to use the short wavelength infrared (SWIR) wavelength band for the optical signal emitted from the light source, but when converting the SWIR wavelength band of 1500 nm into a frequency, It is a high frequency signal of 200 THz. For this reason, it is difficult to directly convert an optical signal from a light source or a reflected optical signal from an object from analog to digital. Therefore, in general, an optical mixer is used to convert the signal into a low frequency signal, and then analog-to-digital conversion is performed. However, there are various problems in integrating a low-loss optical mixer on a semiconductor substrate.

Therefore, the present disclosure provides a photodetection device and a distance measurement system that can be easily integrated into semiconductors, have low power consumption, and have excellent distance measurement accuracy.

In order to solve the above problems, according to the present disclosure, a light receiving unit that receives a first optical signal including a plurality of wavelength bands;
a plurality of pixels that generate pixel signals by performing a convolution operation using autocorrelation or cross-correlation based on the first optical signal and the second optical signal;
an analog-to-digital converter that converts the pixel signal from analog to digital to generate a digital signal;
A photodetection device comprising: a Fourier transform processing section that performs Fourier transform processing on the digital signal.

The first optical signal may be a reflected optical signal obtained by reflecting an optical signal including a plurality of wavelength bands emitted by a light emitting unit from an object.

comprising an optical circulator that switches the propagation direction of the optical signal emitted by the light emitting section,
Switching the propagation direction of the optical signal emitted by the light emitting unit by the optical circulator and irradiating the object,
The light receiving section may receive the first optical signal reflected by the object via the optical circulator.

The second optical signal may be the first optical signal or a pulsed optical signal with a predetermined pulse width.

The light receiving section is
a plurality of pixels each having a photoelectric conversion element;
a plurality of first optical waveguides that cause the first optical signal to enter the plurality of pixels at the same timing;
a plurality of second optical waveguides through which the second optical signal is input to the plurality of pixels while being sequentially shifted by a certain delay time;
The plurality of pixels may output a pixel signal obtained by photoelectrically converting the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides and performing a convolution operation. good.

The second optical signal is the first optical signal,
The plurality of pixels generate the pixel signal by performing a convolution operation based on autocorrelation based on the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides. Good too.

Equipped with a pulsed light generator that generates a pulsed light signal with a predetermined pulse width,
The second optical signal is the pulsed optical signal generated by the pulsed optical generator,
The plurality of pixels generate the pixel signal by performing a convolution operation based on cross-correlation based on the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides. Good too.

The plurality of first optical waveguides individually adjust at least one of the optical path length, refractive index, or reflectance of the plurality of first optical waveguides, and transmit the first optical signal to the plurality of pixels at the same timing. It may be made incident on the

The plurality of second optical waveguides individually adjust at least one of the optical path length, refractive index, or reflectance of the plurality of second optical waveguides so that the second optical signals are shifted by a certain delay time. may be incident on the plurality of pixels.

The first optical signal may be an optical signal in an OFDM (Orthogonal Frequency Division Multiplexing) signal format.

The first optical signal includes a plurality of subcarrier signals each having a different frequency band,
Among the plurality of subcarrier signals, at a frequency of a subcarrier signal whose signal strength reaches a peak value, the signal strength of two subcarrier signals adjacent to this subcarrier signal on the frequency axis may be zero.

Equipped with a spectrometer that separates an optical signal including multiple wavelength bands emitted from the light emitting unit into multiple spectral signals each having a different wavelength band,
A plurality of reflected spectral signals obtained by irradiating the plurality of spectral signals onto one or more objects and reflecting the plurality of spectral signals are optically coupled in the spectroscope to generate the first optical signal, which is received by the light receiving section. Good too.

The plurality of spectral signals separated by the spectroscope may propagate in different propagation directions within a predetermined area.

comprising a scanning member that scans the plurality of spectral signals separated by the spectroscope in at least one direction,
The plurality of spectral signals scanned by the scanning member are irradiated onto the object, and the plurality of reflected spectral signals are optically coupled by the spectroscope to generate the first optical signal, and the plurality of reflected spectral signals are optically coupled by the spectrometer to generate the first optical signal, The light may be received at

comprising a refraction direction control member that integrates the spectroscope and the scanning member,
The refraction direction control member may vary the refraction directions of a plurality of spectral signals separated for each wavelength band included in the first optical signal, and propagate in a two-dimensional direction.

It may also include a distance measuring section that measures the distance to the object that reflected the first optical signal based on the result of the Fourier transform process.

It may also include a spectrum analysis section that analyzes frequency components included in the first optical signal based on the result of the Fourier transform process.

According to the present disclosure, a light emitting unit that emits optical signals in a plurality of wavelength bands;
a light receiving unit that receives a first optical signal obtained by reflecting the optical signal emitted by the light emitting unit on an object;
a plurality of pixels that generate pixel signals by performing a convolution operation using autocorrelation or cross-correlation based on the first optical signal and the second optical signal;
an analog-to-digital converter that converts the pixel signal from analog to digital to generate a digital signal;
a Fourier transform processing unit that performs Fourier transform processing on the digital signal;
A distance measuring system is provided, including a distance measuring section that measures a distance to the object based on a result of performing the Fourier transform processing.

The light emitting section may emit an optical signal in an OFDM signal format.

Conceptual diagram of frequency analysis of light using an interferometer. 1A is a diagram showing a modified example of the interferometer of FIG. 1A. FIG. FIG. 7 is a diagram illustrating the processing procedure of the autocorrelation method in more detail. FIG. 3 is a diagram schematically showing convolution calculation processing performed in a light receiving section having a photoelectric conversion element. FIG. 2 is a block diagram of an autocorrelation type photodetection device. FIG. 3 is a diagram illustrating a cross-correlation method. FIG. 2 is a block diagram of a cross-correlation type photodetection device. FIG. 1 is a diagram showing a schematic configuration of a ranging system according to the present disclosure. The figure which shows the result of performing Fourier transform processing on an impulse signal. The figure which shows the result of performing Fourier transform processing on a pulse signal. FIG. 3 is a diagram showing an example of a plurality of OFDM signals included in an incident optical signal. FIG. 9C is a waveform diagram of an OFDM signal obtained by combining the three subcarrier signals of FIG. 9C. FIG. 1 is a diagram showing a schematic configuration of a ranging system according to the present disclosure using an OFDM signal. FIG. 7 is a diagram showing the operation of the light receiving section and simulation waveforms. A diagram showing the relationship between phase angle and phase difference. FIG. 1 is a block diagram showing a first example of a specific configuration of a photodetection device according to the present disclosure. The figure which shows the example which changes the shape of a 1st optical waveguide, and makes optical path amount equal. FIG. 4 is a diagram in which the optical path length is adjusted using materials having different refractive indexes or reflectances. The figure which shows the example which electrically controls the refractive index or reflectance of a 1st optical waveguide, and makes optical path length the same. FIG. 7 is a block diagram showing a second example of a specific configuration of a photodetecting device according to a modified example. FIG. 1 is a block diagram showing an example of a schematic configuration of a vehicle control system. FIG. 3 is an explanatory diagram showing an example of installation positions of an outside-vehicle information detection section and an imaging section.

Hereinafter, embodiments of a photodetector and a distance measuring system will be described with reference to the drawings. Although the main components of the photodetection device and the distance measurement system will be mainly described below, the photodetection device and the distance measurement system may include components and functions that are not shown or explained. The following description does not exclude components or features not shown or described.

Frequency analysis can be performed on light such as short wavelength infrared light by taking optical autocorrelation using an interferometer.

FIG. 1A is a conceptual diagram of performing frequency analysis of light using an interferometer 1. The interferometer 1 in FIG. 1A includes a light source 2, a half mirror 3, a fixed mirror 4, a movable mirror 5, and a light receiving section 6 having a photoelectric conversion element (photodiode) 6a.

The light source 2 emits light in, for example, a short wavelength infrared band or a visible light band. As shown in the waveform w1 of FIG. 1A, the light emitted by the light source 2 includes two or more types of wavelength (frequency) components.

A part of the light from the light source 2 passes through the half mirror 3, is reflected by the fixed mirror 4, is reflected again by the half mirror 3, and enters the photoelectric conversion element 6a. Further, another part of the light from the light source 2 is reflected by the half mirror 3, reflected by the movable mirror 5, transmitted through the half mirror 3, and incident on the photoelectric conversion element 6a.

In this way, the light reflected by the fixed mirror 4 and the light reflected by the movable mirror 5 are incident on the photoelectric conversion element 6a. The movable mirror 5 is periodically moved along the optical axis. Therefore, the optical path length of the light from the light source 2 that is reflected by the half mirror 3 and the movable mirror 5, passes through the half mirror 3, and enters the photoelectric conversion element 6a is changed by the movement of the movable mirror 5.

On the other hand, the optical path length of the light from the light source 2 that passes through the half mirror 3, is reflected by the fixed mirror 4 and the half mirror 3, and enters the photoelectric conversion element 6a is always constant. Therefore, the difference between these two optical path lengths changes according to the movement of the movable mirror 5.

Light having these two optical path lengths is incident on the photoelectric conversion element 6a. The photoelectric conversion element 6a generates a pixel signal by combining the lights of these two optical path lengths. That is, the photoelectric conversion element 6a generates the same pixel signal as when sampling the light reflected by the fixed mirror 4 and incident at the timing when the light reflected by the movable mirror 5 is incident. Since the position of the fixed mirror 4 changes periodically, the photoelectric conversion element 6a can generate the same pixel signal as when the light reflected by the fixed mirror 4 is sampled at a plurality of sampling positions. This pixel signal is represented by a waveform w2, for example. The waveform w2 shows a waveform obtained by analog-to-digital conversion (hereinafter referred to as AD conversion) of the pixel signal output from the photoelectric conversion element 6a while the movable mirror is periodically moved. More specifically, the waveform w2 is a waveform generated by performing a convolution operation while gradually shifting the light reflected by the fixed mirror 4.

Even if the movable mirror 5 is moved at a slow speed, the photoelectric conversion element 6a can generate a pixel signal like the waveform w2, and can sample at high speed according to the wavelength (frequency) of the light from the light source 2. There is no need for AD conversion.

When the pixel signal shown in the waveform w2 is subjected to Fourier transform processing, a plurality of wavelength (frequency) components included in the light emitted by the light source 2 can be extracted, as shown in the waveform w3 in FIG. 1A.

Although FIG. 1A shows an example in which the movable mirror 5 is periodically moved along the optical axis, a configuration in which the propagation delay time of light is periodically varied instead of changing the optical path length by the movable mirror 5 may also be adopted.

FIG. 1B is a diagram showing a modification of the interferometer 1 of FIG. 1A. The interferometer 1a in FIG. 1B includes an optical waveguide 7 and an optical variable delay element 8 instead of the half mirror 3, fixed mirror 4, and movable mirror 5. The optical variable delay element 8 can periodically vary the propagation delay time of light.

Light emitted from the light source 2 is incident on the optical waveguide 7 and the optical variable delay element 8. The time required for the light incident on the optical waveguide 7 to exit from the optical waveguide 7 (propagation delay time) is always constant. On the other hand, the time required for the light incident on the optical variable delay element 8 to exit from the optical variable delay element 8 changes periodically.

Both the light emitted from the optical waveguide 7 and the light emitted from the optical variable delay element 8 are input to the photoelectric conversion element 6a. Since the delay time between the light emitted from the optical waveguide 7 and the light emitted from the optical variable delay element 8 changes periodically, the light receiving section 6 having the photoelectric conversion element 6a can adjust the delay time between the light emitted from the optical waveguide 7 and the light emitted from the optical variable delay element 8. A pixel signal is generated by convolving the light emitted from the optical variable delay element 8. This pixel signal has the same waveform w2 in FIG. 1A. Therefore, by performing Fourier transform processing on this pixel signal, it is possible to extract a plurality of wavelength components included in the light emitted by the light source 2, similarly to the waveform w3.

Figures 1A and 1B show AD conversion of the results of a convolution operation based on autocorrelation between the light emitted by light source 2 and the light that is delayed from the light emitted by light source 2, which is called an autocorrelation method. .

FIGS. 2 and 3 are diagrams illustrating the processing procedure of the autocorrelation method in more detail. FIGS. 2 and 3 show an example in which two frequency components included in a signal that is a combination of two signals having different frequencies are extracted using an autocorrelation method.

FIG. 2 shows waveforms w4 and w5 of two signals to be combined, and a waveform w6 of the combined signal. Since the signal amplitudes of the waveforms w4 and w5 are different, the amplitude of the waveform w6 of the combined signal changes depending on time. In the autocorrelation method, a digital signal is generated by performing a convolution operation between a combined signal and a signal obtained by delaying the combined signal in stages.

FIG. 3 is a diagram schematically showing convolution calculation processing performed in the light receiving section 6 having the photoelectric conversion element 6a. Hereinafter, the combined signal represented by the waveform w6 will be referred to as an incident optical signal, and a signal obtained by delaying the incident optical signal in stages will be referred to as a delayed optical signal.

Each photoelectric conversion element 6a in the light receiving section 6 receives an incident optical signal having the same phase and delayed optical signals having different delay amounts. The light receiving section 6 having each photoelectric conversion element 6a performs a convolution operation and AD conversion on the incident optical signal w6 and the delayed optical signal w7. As a result, a digital signal shown in waveform w8 is generated. Next, Fourier transform processing is performed on the digital signal. As a result, two frequency components included in the incident optical signal w6 are extracted, as shown in the waveform w9.

The delay amounts of the plurality of delayed optical signals w7 are different by equal amounts, and the signal representing the result of the convolution operation between these delayed optical signals 27 and the input optical signal w6 is obtained by sampling the input optical signal w6 at high speed. There is a correlation with the signal.

FIG. 4 is a block diagram of an autocorrelation type photodetector 10a. The photodetecting device 10a in FIG. 4 includes a light receiving section 11 having a plurality of photoelectric conversion elements 11a, an AD converter (ADC: Analog Digital Converter) 12, and a Fourier transform processing section (FFT: Fast Fourier Transform) 13. .

Each photoelectric conversion element 11a in the light receiving section 11 receives an incident optical signal and a delayed optical signal obtained by delaying the incident optical signal in stages. The phases of the incident optical signals incident on each photoelectric conversion element 11a are the same, and the incident optical signals of the same phase are incident on the photoelectric conversion elements 11a at the same timing. The delayed optical signal input to each photoelectric conversion element 11a has a delay amount shifted by the same amount for each photoelectric conversion element 11a.

The pixel signal generated by each pixel photoelectric conversion element 11a is a signal obtained by performing a convolution operation on an incident optical signal and a delayed optical signal, and is represented by a waveform w13, for example. The AD converter 12 converts pixel signals photoelectrically converted by the plurality of photoelectric conversion elements 11a into digital signals. The light receiving unit 11 and the AD converter 12 perform convolution calculation and AD conversion of the incident optical signal and the delayed optical signal. The Fourier transform processing unit 13 extracts a plurality of frequency components included in the incident optical signal based on the digital signal.

In addition to the autocorrelation method, there is a method called a cross-correlation method as a method for extracting a plurality of frequency components included in an incident optical signal. FIG. 5 is a diagram illustrating the cross-correlation method. Similar to FIG. 2, FIG. 5 shows an example in which frequency analysis is performed on an incident optical signal having a waveform w6, which is a combination of two signals represented by waveforms w4 and w5.

In the cross-correlation method, an incident optical signal (waveform w6) having the same phase is inputted to a plurality of photoelectric conversion elements 11a, and a pulsed optical signal (waveform w10) delayed in stages is inputted to the plurality of photoelectric conversion elements 11a. That is, the pulsed optical signals incident on each photoelectric conversion element 11a differ in phase by the same amount. The light receiving unit 11 having each photoelectric conversion element 11a generates a pixel signal by performing a convolution operation on an incident optical signal and a pulsed optical signal, and then performs AD conversion on the pixel signal to generate a digital signal shown in a waveform w11. do. The waveform w11 of the digital signal obtained by the cross-correlation method is similar to the waveform w8 of the digital signal obtained by the autocorrelation method, and a frequency analysis result of the waveform w12 similar to the waveform w9 can be obtained.

FIG. 6 is a block diagram of a cross-correlation type photodetector 10b. Similar to the photodetection device 10a in FIG. 4, the photodetection device 10b in FIG. 6 includes a light receiving section 11 having a plurality of photoelectric conversion elements 11a, an AD converter 12, and a Fourier transform processing section 13. It has a pulsed light generator 14.

The pulsed light generator 14 generates a pulsed light signal with a predetermined pulse width. An incident optical signal and a stepwise delayed pulsed optical signal are input to each photoelectric conversion element 11a in the light receiving section 11. The light receiving section 11 having each photoelectric conversion element 11a performs a convolution operation based on the incident optical signal and the pulsed optical signal to generate a pixel signal as shown in the waveform w14, for example. This pixel signal is converted into a digital signal by the AD converter 12. The Fourier transform processing unit 13 extracts a plurality of frequency components included in the incident optical signal based on the digital signal.

As explained above, a digital signal is generated by performing a convolution operation using an autocorrelation method or a cross-correlation method at each pixel in the light receiving section 11 on an incident optical signal containing a plurality of frequency components (wavelength components). can be generated without using a high-speed AD converter. Therefore, the circuit scale can be reduced and power consumption can also be reduced.

Further, the generated digital signal includes a plurality of frequency components included in the incident optical signal, and by performing Fourier transform processing after AD conversion, distance measurement and frequency analysis can be performed.

FIG. 7 is a diagram showing a schematic configuration of a ranging system 20 according to the present disclosure. The distance measuring system 20 in FIG. 7 includes a light source 2, a circulator 21, and a light receiving section 11. The light source 2 emits optical signals in multiple wavelength (frequency) bands. The circulator 21 switches the propagation direction of the optical signal emitted by the light source 2 and propagates it in the direction of the object 15 . When the optical signal whose propagation direction has been switched by the circulator 21 is irradiated onto the object 15, it is reflected by the object 15, and the reflected optical signal propagates in the opposite direction and enters the circulator 21. The circulator 21 guides the reflected light signal to the light receiving section 11 .

When adopting the autocorrelation method, the light receiving unit 11 inputs a reflected light signal and a delayed light signal obtained by delaying the reflected light signal in stages to a plurality of pixels, and performs a convolution operation within each pixel. A pixel signal indicating the result is generated. This pixel signal is converted into a digital signal by an AD converter (not shown in FIG. 7). The digital signal is input to a Fourier transform processing unit (not shown in FIG. 7), and a plurality of frequency components included in the digital signal are extracted. The distance to the object 15 can be measured from the phase difference between the plurality of extracted frequency components.

To measure distance, the optical signal emitted by the light source 2 needs to contain signal components in multiple wavelength (frequency) bands. In this embodiment, an OFDM (Orthogonal Frequency Division Multiplexing) signal can be used as an optical signal including signal components of multiple wavelength (frequency) bands.

FIGS. 8A and 8B are diagrams illustrating OFDM signals. When Fourier transform processing is performed on the impulse signal shown in FIG. 8A, a frequency analysis result that equally includes all frequency components is obtained. Furthermore, as shown in FIG. 8B, when a Fourier transform process is performed on a pulse signal having a predetermined pulse width, the signal intensity reaches a peak value at a predetermined frequency, and the signal intensity becomes zero at every fixed frequency. Frequency analysis results are obtained.

An OFDM signal includes a plurality of subcarrier signals each having a different frequency at which the signal strength reaches its peak value, and when the signal strength of one subcarrier signal reaches its peak value, the signal strength of other subcarrier signals becomes zero. That's what I do. Although an OFDM signal includes a plurality of subcarrier signals each having a different frequency at which the signal strength reaches its peak value, it has a feature that these subcarrier signals do not interfere with each other.

FIG. 9 is a diagram showing an example of a plurality of OFDM signals included in the incident optical signal. The horizontal axis in FIG. 9 is frequency, and the vertical axis is signal strength. The OFDM signal in FIG. 9 shows an example including three subcarrier signals. FIG. 9A shows pulse signals having different phases and the same pulse width. FIG. 9B shows signals generated by performing inverse Fourier transform processing on the three pulse signals shown in FIG. 9A. FIG. 9C shows the absolute value of a signal generated by performing inverse Fourier transform processing on the three pulse signals in FIG. 9A, and corresponds to the subcarrier signal. The OFDM signal is obtained, for example, by combining the three waveforms shown in FIG. 9C.

FIG. 10 is a waveform diagram of an OFDM signal obtained by combining the three subcarrier signals w15, w16, and w17 of FIG. 9C. The horizontal axis in FIG. 10 is frequency, and the vertical axis is signal strength. In the OFDM signal of FIG. 10, the phases of subcarrier signals of adjacent frequencies are made orthogonal to each other, and part of the frequency band is overlapped. At a time position where the signal strength of one subcarrier signal is at its peak, the signal strength of other subcarrier signals is zero.

OFDM signals are widely used in wireless communications because they are resistant to multipath. OFDM signals used in wireless communication can undergo amplitude modulation, frequency modulation, phase modulation, etc. on the peak value. In this embodiment, since the OFDM signal is used for frequency analysis or distance measurement, there is no need to modulate the peak value.

OFDM signals have a phase shift due to multipath. Particularly in the case of phase modulation, symbol rotation occurs. For this reason, an equalizer is provided in the OFDM receiver. The equalizer detects and corrects multipath caused by obstacles such as buildings and mountains. In this way, the equalizer has the function of detecting and correcting obstacles. This means that the distance to an obstacle can be detected. In this embodiment, the distance to an obstacle (object 15) is measured using an OFDM signal that is resistant to multipath, instead of providing an equalizer to correct multipath.

As shown in FIG. 10, the OFDM signal includes a plurality of subcarrier signals, and each subcarrier signal has a different frequency at which the signal strength peaks. By converting the optical signal emitted by the light source 2 into an OFDM signal, it is possible to simultaneously measure the distances of a plurality of objects 15 located within a predetermined area. By increasing the number of subcarrier signals included in the optical signal emitted by the light source 2, the distances of more objects 15 can be measured simultaneously.

FIG. 11 is a diagram showing a schematic configuration of a ranging system 20a according to the present disclosure using an OFDM signal. The distance measuring system 20a in FIG. 11 includes a light source 2a, a circulator 21, a light receiving section 11, a spectroscope 22, and a scanning member 23.

The light source 2a emits an optical signal in the OFDM signal format shown in FIG. The light source 2a has a plurality of light emitting sections that emit optical signals in each subcarrier signal format included in the OFDM signal, and an OFDM signal format is generated by the plurality of optical signals emitted from these light emitting sections. . Alternatively, an optical signal including a plurality of subcarrier signals may be emitted from one light emitting section. When an optical signal including a plurality of subcarrier signals is emitted from one light emitting section, the optical intensity of each subcarrier signal component can be suppressed, which is desirable from the viewpoint of laser safety.

The circulator 21 switches the propagation direction of the optical signal emitted by the light source 2a. The circulator 21 switches between propagating the optical signal emitted by the light source 2 a in the direction of the spectroscope 22 and propagating the reflected optical signal from the object 15 in the direction of the light receiving section 11 .

The spectrometer 22 separates the optical signal emitted by the light source 2a into a plurality of directions for each wavelength (frequency). Since the optical signal emitted by the light source 2a is an OFDM signal, it includes a plurality of subcarrier signals each having a different frequency at which the signal intensity reaches its peak value. The spectrometer 22 separates the optical signal into a plurality of spectral signals. Each spectral signal includes any subcarrier signal component included in the optical signal emitted by the light source 2a. The plurality of spectral signals separated by the spectrometer 22 propagate in different directions, and are used to measure the distance to the object 15 located in the propagation direction.

The spectrometer 22 is, for example, a prism. A prism refracts incident light in different directions for each wavelength (frequency) band. Thereby, the prism splits the incident light into a plurality of spectral signals, and causes each spectral signal to propagate in separate directions.

The spectrometer 22 may be any refractive index control member that changes the refractive index for each wavelength (frequency) band, and does not necessarily need to use a prism.

In the example of FIG. 11, the distance of the object 15 existing within the predetermined area 24 in the first direction y of the two-dimensional area, which is the detection range of the object 15, is simultaneously measured using a plurality of spectral signals separated by the spectrometer 22. It can be carried out. Reflected light from one or more objects 15 existing within the predetermined region 24 in the first direction y is incident on the spectrometer 22 at a time corresponding to the distance to the object 15. The spectrometer 22 optically couples reflected light from one or more objects 15 existing within a predetermined region 24 in the first direction y, and makes the light enter the light receiving section 11 .

The scanning member 23 can scan the plurality of spectral signals separated by the spectroscope 22 in the second direction x of the two-dimensional area. The scanning member 23 has, for example, a reflecting mirror rotatable around at least one axis, and reflects the plurality of spectral signals separated by the spectroscope 22 to scan the two-dimensional area in the second direction x. Thereby, while scanning the predetermined region 24 extending in the first direction y in the second direction x, it is possible to measure the distance of one or more objects 15 located in the entire two-dimensional region for each predetermined region 24.

A refraction direction control member in which the spectroscope 22 and scanning member 23 of FIG. 11 are integrated may be provided. The refraction direction control member separates the light signal from the light source 2a into a plurality of spectral signals for each wavelength (frequency) band, and propagates the spectral signals in a two-dimensional direction by changing the refraction direction of each of the spectral signals. Thereby, even without providing the spectroscope 22 and the scanning member 23, it is possible to irradiate the plurality of objects 15 located within the three-dimensional area with the spectral signal. The reflected spectral signals from the plurality of objects 15 irradiated with the plurality of spectral signals are optically coupled by the refraction direction control member and enter the light receiving section 11 via the circulator 21 .

FIG. 12 is a diagram showing the operation of the light receiving unit 11 and simulation waveforms when measuring the distance to the object 15 in a three-dimensional (spatial) area using the distance measuring system 20a of FIG. 11. FIG. 12 shows simulation results when the light source 2a emits an optical signal in the OFDM signal format including three subcarrier signals as shown in FIG. The propagation direction of the optical signal emitted by the light source 2 a is switched by the circulator 21 and is input to the spectrometer 22 . The spectrometer 22 separates the three subcarrier signals included in the optical signal into separate spectral signals. The three spectral signals separated by the spectrometer 22 propagate in different directions and are used to measure distances to different objects 15. The reflected optical signals from the object 15 located in the propagation direction of each spectral signal are incident on the spectrometer 22 through the opposite path. The spectrometer 22 optically couples these three reflected optical signals and inputs them into the circulator 21 . The circulator 21 guides the reflected light signal from the spectrometer 22 to the light receiving section 11 .

A waveform w21 in FIG. 12 is a waveform of a digital signal obtained by AD converting a pixel signal output from each pixel when an incident optical signal and a delayed optical signal are input to each pixel in the light receiving section 11. The horizontal axis of the waveform w21 is time, and the vertical axis is the signal level of the digital signal.

A waveform w22 in FIG. 12 shows the absolute value of a digital signal subjected to Fourier transform processing by the Fourier transform processing unit 13. The horizontal axis of the waveform w22 is the frequency, and the vertical axis is the absolute value after Fourier transform processing. The peak value of each subcarrier appears in the waveform w22.
The waveform w23 in FIG. 12 shows the result of performing complex Fourier transform processing on the digital signal. The horizontal axis of the waveform w23 is the phase angle, and the vertical axis is the value of the phase angle which is the result of Fourier transform processing of complex numbers. The differential (slope) of the phase angle represents the phase difference. As shown in FIG. 13, the slope of the phase angle is the phase difference, which is obtained by differentiating the phase angle.

Waveform w24 in FIG. 12 is a waveform diagram obtained by differentiating the phase angle of waveform w23. The horizontal axis of the waveform w24 is the phase angle, and the vertical axis is the phase difference. The waveform w24 is a horizontally symmetrical waveform and has a stepped waveform shape. The stepped waveform shape represents a phase difference. The phase difference represents the amount of delay of the three subcarriers in FIG. 8(C), and represents the distance to the three objects 15 irradiated with the three spectral signals.

In this way, the light source 2a emits an optical signal in the OFDM signal format including a plurality of subcarrier signals, so that one or more objects 15 located within the predetermined area 24 in the first direction y in the three-dimensional spatial area can be detected. Distances can be measured simultaneously. Further, by providing the scanning member 23, the distances of the plurality of objects 15 located within the three-dimensional spatial region can be measured.

FIG. 14 is a block diagram showing a first example of a specific configuration of a photodetection device 10c according to the present disclosure. The photodetector 10c in FIG. 14 includes a pixel chip 31 and a logic chip 32. The pixel chip 31 and the logic chip 32 are stacked and transmit various signals using, for example, Cu--Cu junctions, vias, bumps, and the like. Note that the photodetecting device 10c in FIG. 14 may be configured as a single chip without being divided into the pixel chip 31 and the logic chip 32. Alternatively, the photodetecting device 10c may be configured by stacking three or more chips.

The pixel chip 31 in FIG. 14 includes a plurality of pixels 33, a plurality of first optical waveguides 34, a plurality of second optical waveguides 35, an AD converter 12, and a DA converter (DAC: Digital Analog Converter) 36. has.

A reflected light signal from the object 15 is incident on the pixel chip 31 in FIG. As shown in FIG. 11, the reflected light signal from the object 15 is reflected by a plurality of objects 15, optically coupled by the spectroscope 22, and then input to the pixel chip 31. More specifically, the reflected light signal is not directly incident on the plurality of pixels 33 within the pixel chip 31, but is incident on the plurality of first optical waveguides 34 on the pixel chip 31.

The plurality of first optical waveguides 34 are a plurality of branch waveguides branched from the incident position of the reflected optical signal, and each branch waveguide extends to the corresponding pixel 33. The distance from the incident position of the reflected optical signal in the plurality of first optical waveguides 34 to each pixel 33 is made equal. Thereby, the reflected optical signals propagated through the plurality of first optical waveguides 34 are incident on the plurality of pixels 33 at the same timing.

As shown in FIG. 14, the incident positions of the reflected optical signals in the plurality of first optical waveguides 34 are located at the outer periphery of the pixel chip 31, and the linear distances from the incident positions to each pixel 33 are different. For this reason, as shown in FIG. 15A, the first optical waveguide 34 from the incident position to the pixel 33 having a short straight line distance is made wave-like to increase the optical path length. Alternatively, as shown in FIG. 15B, in the first optical waveguide 34 up to the pixel 33 where the direct distance from the incident position of the reflected light signal is short, and in the first optical waveguide 34 up to the pixel 33 where the direct distance from the incident position is long, The optical path length is adjusted by using materials with mutually different refractive indexes or reflectances. Alternatively, as shown in FIG. 15C, the refractive index or reflectance of the first optical waveguide 34 is controlled by controlling the voltage V applied to the first optical waveguide 34 according to the distance from the incident position of the reflected light signal to the pixel 33. are electrically controlled to make the optical path length the same.

The plurality of second optical waveguides 35 are a plurality of branch waveguides branched from the same incident position of the reflected optical signal as the first optical waveguide 34 . The optical path lengths from the incident position of the reflected optical signal to each pixel 33 in the plurality of second optical waveguides 35 differ by the same amount. That is, the amount of delay of the reflected optical signal propagated in each second optical waveguide 35 is different by the same amount.

To make the optical path lengths of the plurality of second optical waveguides 35 different for each pixel 33, for example, the method shown in FIG. 15A, FIG. 15B, or FIG. 15C described above is used.

In this way, reflected optical signals are simultaneously incident on the plurality of pixels 33 through the plurality of first optical waveguides 34, and reflected optical signals shifted by a predetermined amount of delay are transmitted through the plurality of second optical waveguides 35. It is incident. As shown in the partially enlarged view of FIG. 14, a reflective member 16 is attached to the end portions of the plurality of first optical waveguides 34 and the plurality of second optical waveguides 35 on the pixel 33 side, and the first optical waveguides 34 and The reflected optical signal that has propagated through the second optical waveguide 35 is reflected by the reflecting member 16 and enters each pixel 33 .

The plurality of pixels 33 receive a reflected optical signal (first optical signal) propagated in the first optical waveguide 34 and a reflected optical signal (second optical signal) propagated in the second optical waveguide 35. Then, a pixel signal is generated by performing a convolution operation using an autocorrelation method. The generated pixel signal is input to the AD converter 12 via the signal line Sig. A plurality of signal lines Sig are provided at regular intervals in the column direction.

The AD converter 12 on the pixel chip 31 has a comparator 37 and a counter 38. The comparator 37 compares the pixel signal transmitted from each pixel 33 via the signal line Sig with the reference signal generated by the DA converter 36. The reference signal is a ramp wave signal whose signal level changes over time. The comparator 37 changes the output signal level when the pixel signal and the reference signal match. The counter 38 continues counting until the comparator 37 detects a match. The count value of the counter 38 when a match is detected by the comparator 37 is sent to the connection unit 39 as a digital signal obtained by AD converting the pixel signal.

The logic chip 32 is provided with a connection section 40 and a Fourier transform processing section 13. The connection section 39 on the pixel chip 31 and the connection section 40 on the logic chip 32 are arranged at opposing positions, and transmit and receive various signals via, for example, a Cu--Cu joint. Specifically, the digital signal generated by the AD converter 12 on the pixel chip 31 is input to the Fourier transform processing section 13 on the logic chip 32 via the connection sections 39 and 40.

The Fourier transform processing unit 13 performs Fourier transform processing on the digital signal to detect a phase difference between a plurality of subcarrier signal components included in the digital signal. The distance to the object 15 can be measured based on the detected phase difference.

In addition, the logic chip 32 may be provided with at least one of a distance measuring section 41 and a spectrum analysis section (frequency analysis section) 42. The distance measuring unit 41 measures the distance to the object 15 that reflected the reflected light signal based on the result of Fourier transform processing. The spectrum analysis unit 42 analyzes frequency components included in the reflected light signal based on the results of Fourier transform processing.

FIG. 16 is a block diagram showing a second example of a specific configuration of a photodetecting device 10d according to a modified example. The photodetector 10d in FIG. 16 performs convolution calculation using a cross-correlation method.

The photodetector 10d in FIG. 16 differs from the photodetector 10c in FIG. 14 in the configuration on the pixel chip 31 side. On the pixel chip 31 of FIG. 16, in addition to the configuration of FIG. 14, a pulsed light generator 14 is provided. The pulsed light generator 14 generates a pulsed light signal with a predetermined pulse width. The pulsed light signal emitted from the pulsed light generator 14 is incident on the plurality of pixels 33 via the plurality of second optical waveguides 35 . The plurality of second optical waveguides 35 delay the pulsed light by an equal amount, and the delayed pulsed light enters each pixel 33 . That is, the timings of the pulsed optical signals that are incident on the plurality of pixels 33 differ by a predetermined amount of delay.

Each of the plurality of pixels 33 receives a reflected optical signal (first optical signal) propagated in the corresponding first optical waveguide 34 and a pulsed optical signal (second optical signal) propagated in the corresponding second optical waveguide 35. ) and performs a convolution operation using a cross-correlation method to generate a pixel signal. The processing operations of the AD converter 12 and the Fourier transform processing unit 13 are similar to those shown in FIG. 14, and the distance to the object 15 can be measured based on the phase difference between the plurality of subcarrier signals included in the digital signal.

In this way, in this embodiment, the light source 2a emits an optical signal including a plurality of wavelength (frequency) components and irradiates the object 15, and the reflected light signal from the object 15 is received by the plurality of pixels 33. A plurality of pixels 33 receive a delayed optical signal obtained by shifting the reflected light signal in steps, or a delayed pulsed optical signal obtained by shifting the pulsed optical signal in steps. Then, the plurality of pixels 33 performs a convolution operation using an autocorrelation method or a cross-correlation method to generate pixel signals. The distance to the object 15 is measured by converting the generated pixel signal into a digital signal and performing frequency analysis to detect the phase difference.

According to this embodiment, AD conversion can be performed without sampling the reflected light signal, which is a high frequency signal, at high speed, and it is possible to suppress hardware costs and reduce power consumption.

Furthermore, in this embodiment, since the light source 2a emits an optical signal in the OFDM signal format, the spectrometer 22 separates the signal into a plurality of spectral signals, and the distances of a plurality of objects 15 within the predetermined area 24 can be measured simultaneously. Thereby, by simply scanning the scanning member 23 in one-dimensional direction, the distance of the object 15 located in the three-dimensional space can be measured at high speed.

Furthermore, in this embodiment, AD conversion processing and Fourier transformation processing are performed after the pixel signal is generated by performing convolution calculation using the autocorrelation method or the cross-correlation method, making it easy to extract multiple frequency components included in the optical signal. It can be used as a photodetector.

(Application example)
The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure can be applied to any type of transportation such as a car, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility vehicle, an airplane, a drone, a ship, a robot, a construction machine, an agricultural machine (tractor), etc. It may also be realized as a device mounted on the body.

FIG. 17 is a block diagram illustrating a schematic configuration example of a vehicle control system 7000, which is an example of a mobile body control system to which the technology according to the present disclosure can be applied. Vehicle control system 7000 includes multiple electronic control units connected via communication network 7010. In the example shown in FIG. 17, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an outside vehicle information detection unit 7400, an inside vehicle information detection unit 7500, and an integrated control unit 7600. . The communication network 7010 connecting these plurality of control units is, for example, a network based on any standard such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), or FlexRay (registered trademark). It may be an in-vehicle communication network.

Each control unit includes a microcomputer that performs calculation processing according to various programs, a storage unit that stores programs executed by the microcomputer or parameters used in various calculations, and a drive circuit that drives various devices to be controlled. Equipped with. Each control unit is equipped with a network I/F for communicating with other control units via the communication network 7010, and also communicates with devices or sensors inside and outside the vehicle through wired or wireless communication. A communication I/F is provided for communication. In FIG. 17, the functional configuration of the integrated control unit 7600 includes a microcomputer 7610, a general-purpose communication I/F 7620, a dedicated communication I/F 7630, a positioning section 7640, a beacon receiving section 7650, an in-vehicle device I/F 7660, an audio image output section 7670, An in-vehicle network I/F 7680 and a storage unit 7690 are illustrated. The other control units similarly include a microcomputer, a communication I/F, a storage section, and the like.

Drive system control unit 7100 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 7100 includes a drive force generation device such as an internal combustion engine or a drive motor that generates drive force for the vehicle, a drive force transmission mechanism that transmits the drive force to wheels, and a drive force transmission mechanism that controls the steering angle of the vehicle. It functions as a control device for the steering mechanism to adjust and the braking device to generate the braking force of the vehicle. The drive system control unit 7100 may have a function as a control device such as ABS (Antilock Brake System) or ESC (Electronic Stability Control).

A vehicle state detection section 7110 is connected to the drive system control unit 7100. The vehicle state detection unit 7110 includes, for example, a gyro sensor that detects the angular velocity of the axial rotation movement of the vehicle body, an acceleration sensor that detects the acceleration of the vehicle, or an operation amount of an accelerator pedal, an operation amount of a brake pedal, or a steering wheel. At least one sensor for detecting angle, engine rotational speed, wheel rotational speed, etc. is included. The drive system control unit 7100 performs arithmetic processing using signals input from the vehicle state detection section 7110, and controls the internal combustion engine, the drive motor, the electric power steering device, the brake device, and the like.

The body system control unit 7200 controls the operations of various devices installed in the vehicle body according to various programs. For example, the body system control unit 7200 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as a headlamp, a back lamp, a brake lamp, a turn signal, or a fog lamp. In this case, radio waves transmitted from a portable device that replaces a key or signals from various switches may be input to the body control unit 7200. The body system control unit 7200 receives input of these radio waves or signals, and controls the door lock device, power window device, lamp, etc. of the vehicle.

Battery control unit 7300 controls secondary battery 7310, which is a power supply source for the drive motor, according to various programs. For example, information such as battery temperature, battery output voltage, or remaining battery capacity is input to the battery control unit 7300 from a battery device including a secondary battery 7310. The battery control unit 7300 performs arithmetic processing using these signals, and controls the temperature adjustment of the secondary battery 7310 or the cooling device provided in the battery device.

External information detection unit 7400 detects information external to the vehicle in which vehicle control system 7000 is mounted. For example, at least one of an imaging section 7410 and an external information detection section 7420 is connected to the vehicle exterior information detection unit 7400. The imaging unit 7410 includes at least one of a ToF (Time Of Flight) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The vehicle external information detection unit 7420 includes, for example, an environmental sensor for detecting the current weather or weather, or a sensor for detecting other vehicles, obstacles, pedestrians, etc. around the vehicle equipped with the vehicle control system 7000. At least one of the surrounding information detection sensors is included.

The environmental sensor may be, for example, at least one of a raindrop sensor that detects rainy weather, a fog sensor that detects fog, a sunlight sensor that detects the degree of sunlight, and a snow sensor that detects snowfall. The surrounding information detection sensor may be at least one of an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. The imaging section 7410 and the vehicle external information detection section 7420 may be provided as independent sensors or devices, or may be provided as a device in which a plurality of sensors or devices are integrated.

Here, FIG. 18 shows an example of the installation positions of the imaging section 7410 and the external information detection section 7420. The imaging units 7910, 7912, 7914, 7916, and 7918 are provided, for example, at at least one of the front nose, side mirrors, rear bumper, back door, and upper part of the windshield inside the vehicle 7900. An imaging unit 7910 provided in the front nose and an imaging unit 7918 provided above the windshield inside the vehicle mainly acquire images in front of the vehicle 7900. Imaging units 7912 and 7914 provided in the side mirrors mainly capture images of the sides of the vehicle 7900. An imaging unit 7916 provided in the rear bumper or back door mainly acquires images of the rear of the vehicle 7900. The imaging unit 7918 provided above the windshield inside the vehicle is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, and the like.

Note that FIG. 18 shows an example of the imaging range of each of the imaging units 7910, 7912, 7914, and 7916. Imaging range a indicates the imaging range of imaging unit 7910 provided on the front nose, imaging ranges b and c indicate imaging ranges of imaging units 7912 and 7914 provided on the side mirrors, respectively, and imaging range d is The imaging range of an imaging unit 7916 provided in the rear bumper or back door is shown. For example, by superimposing image data captured by imaging units 7910, 7912, 7914, and 7916, an overhead image of vehicle 7900 viewed from above can be obtained.

The vehicle exterior information detection units 7920, 7922, 7924, 7926, 7928, and 7930 provided at the front, rear, side, corner, and upper part of the windshield inside the vehicle 7900 may be, for example, ultrasonic sensors or radar devices. External information detection units 7920, 7926, and 7930 provided on the front nose, rear bumper, back door, and upper part of the windshield inside the vehicle 7900 may be, for example, LIDAR devices. These external information detection units 7920 to 7930 are mainly used to detect preceding vehicles, pedestrians, obstacles, and the like.

Returning to FIG. 17, the explanation will be continued. The vehicle exterior information detection unit 7400 causes the imaging unit 7410 to capture an image of the exterior of the vehicle, and receives the captured image data. Further, the vehicle exterior information detection unit 7400 receives detection information from the vehicle exterior information detection section 7420 to which it is connected. When the external information detection unit 7420 is an ultrasonic sensor, a radar device, or a LIDAR device, the external information detection unit 7400 transmits ultrasonic waves, electromagnetic waves, etc., and receives information on the received reflected waves. The external information detection unit 7400 may perform object detection processing such as a person, car, obstacle, sign, or text on the road surface or distance detection processing based on the received information. The external information detection unit 7400 may perform environment recognition processing to recognize rain, fog, road surface conditions, etc. based on the received information. The vehicle exterior information detection unit 7400 may calculate the distance to the object outside the vehicle based on the received information.

Further, the external information detection unit 7400 may perform image recognition processing or distance detection processing for recognizing people, cars, obstacles, signs, characters on the road surface, etc., based on the received image data. The outside-vehicle information detection unit 7400 performs processing such as distortion correction or alignment on the received image data, and also synthesizes image data captured by different imaging units 7410 to generate an overhead image or a panoramic image. Good too. The outside-vehicle information detection unit 7400 may perform viewpoint conversion processing using image data captured by different imaging units 7410.

The in-vehicle information detection unit 7500 detects in-vehicle information. For example, a driver condition detection section 7510 that detects the condition of the driver is connected to the in-vehicle information detection unit 7500. The driver state detection unit 7510 may include a camera that images the driver, a biosensor that detects biometric information of the driver, a microphone that collects audio inside the vehicle, or the like. The biosensor is provided, for example, on a seat surface or a steering wheel, and detects biometric information of a passenger sitting on a seat or a driver holding a steering wheel. The in-vehicle information detection unit 7500 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 7510, or determine whether the driver is dozing off. You may. The in-vehicle information detection unit 7500 may perform processing such as noise canceling processing on the collected audio signal.

Integrated control unit 7600 controls overall operations within vehicle control system 7000 according to various programs. An input section 7800 is connected to the integrated control unit 7600. The input unit 7800 is realized by, for example, a device such as a touch panel, a button, a microphone, a switch, or a lever that can be inputted by the passenger. The integrated control unit 7600 may be input with data obtained by voice recognition of voice input through a microphone. Input unit 7800 may be, for example, a remote control device that uses infrared rays or other radio waves, or may be an external connection device such as a mobile phone or PDA (Personal Digital Assistant) that supports operation of vehicle control system 7000. You can. The input unit 7800 may be, for example, a camera, in which case the passenger can input information using gestures. Alternatively, data obtained by detecting the movement of a wearable device worn by a passenger may be input. Further, the input section 7800 may include, for example, an input control circuit that generates an input signal based on information input by a passenger or the like using the input section 7800 described above and outputs it to the integrated control unit 7600. By operating this input unit 7800, a passenger or the like inputs various data to the vehicle control system 7000 and instructs processing operations.

The storage unit 7690 may include a ROM (Read Only Memory) that stores various programs executed by the microcomputer, and a RAM (Random Access Memory) that stores various parameters, calculation results, sensor values, and the like. Furthermore, the storage unit 7690 may be realized by a magnetic storage device such as an HDD (Hard Disc Drive), a semiconductor storage device, an optical storage device, a magneto-optical storage device, or the like.

The general-purpose communication I/F 7620 is a general-purpose communication I/F that mediates communication with various devices existing in the external environment 7750. The general-purpose communication I/F 7620 supports cellular communication protocols such as GSM (registered trademark) (Global System of Mobile communications), WiMAX (registered trademark), LTE (registered trademark) (Long Term Evolution), or LTE-A (LTE-Advanced). , or other wireless communication protocols such as wireless LAN (also referred to as Wi-Fi (registered trademark)) or Bluetooth (registered trademark). The general-purpose communication I/F 7620 connects to a device (for example, an application server or a control server) existing on an external network (for example, the Internet, a cloud network, or an operator-specific network) via a base station or an access point, for example. You may. In addition, the general-purpose communication I/F 7620 uses, for example, P2P (Peer To Peer) technology to connect terminals located near the vehicle (for example, terminals of drivers, pedestrians, stores, or MTC (Machine Type Communication) terminals). You can also connect it with

The dedicated communication I/F 7630 is a communication I/F that supports communication protocols developed for use in vehicles. The dedicated communication I/F 7630 supports standard protocols such as WAVE (Wireless Access in Vehicle Environment), DSRC (Dedicated Short Range Communications), which is a combination of lower layer IEEE802.11p and upper layer IEEE1609, or cellular communication protocol. May be implemented. The dedicated communication I/F 7630 typically supports vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication. ) communications, a concept that includes one or more of the following:

The positioning unit 7640 performs positioning by receiving, for example, a GNSS signal from a GNSS (Global Navigation Satellite System) satellite (for example, a GPS signal from a GPS (Global Positioning System) satellite), and determines the latitude, longitude, and altitude of the vehicle. Generate location information including. Note that the positioning unit 7640 may specify the current location by exchanging signals with a wireless access point, or may acquire location information from a terminal such as a mobile phone, PHS, or smartphone that has a positioning function.

The beacon receiving unit 7650 receives, for example, radio waves or electromagnetic waves transmitted from a wireless station installed on a road, and obtains information such as the current location, traffic congestion, road closure, or required time. Note that the function of the beacon receiving unit 7650 may be included in the dedicated communication I/F 7630 described above.

The in-vehicle device I/F 7660 is a communication interface that mediates connections between the microcomputer 7610 and various in-vehicle devices 7760 present in the vehicle. The in-vehicle device I/F 7660 may establish a wireless connection using a wireless communication protocol such as wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), or WUSB (Wireless USB). The in-vehicle device I/F 7660 also connects USB (Universal Serial Bus), HDMI (registered trademark) (High-Definition Multimedia Interface), or MHL (Mobile High The in-vehicle device 7760 may include, for example, at least one of a mobile device or wearable device owned by a passenger, or an information device carried into or attached to the vehicle. In addition, the in-vehicle device 7760 may include a navigation device that searches for a route to an arbitrary destination. or exchange data signals.

In-vehicle network I/F 7680 is an interface that mediates communication between microcomputer 7610 and communication network 7010. The in-vehicle network I/F 7680 transmits and receives signals and the like in accordance with a predetermined protocol supported by the communication network 7010.

The microcomputer 7610 of the integrated control unit 7600 communicates via at least one of a general-purpose communication I/F 7620, a dedicated communication I/F 7630, a positioning section 7640, a beacon reception section 7650, an in-vehicle device I/F 7660, and an in-vehicle network I/F 7680. The vehicle control system 7000 is controlled according to various programs based on the information obtained. For example, the microcomputer 7610 calculates a control target value for a driving force generating device, a steering mechanism, or a braking device based on acquired information inside and outside the vehicle, and outputs a control command to the drive system control unit 7100. Good too. For example, the microcomputer 7610 realizes ADAS (Advanced Driver Assistance System) functions, including vehicle collision avoidance or impact mitigation, following distance based on vehicle distance, vehicle speed maintenance, vehicle collision warning, vehicle lane departure warning, etc. Coordination control may be performed for the purpose of In addition, the microcomputer 7610 controls the driving force generating device, steering mechanism, braking device, etc. based on the acquired information about the surroundings of the vehicle, so that the microcomputer 7610 can drive the vehicle autonomously without depending on the driver's operation. Cooperative control for the purpose of driving etc. may also be performed.

The microcomputer 7610 acquires information through at least one of a general-purpose communication I/F 7620, a dedicated communication I/F 7630, a positioning section 7640, a beacon reception section 7650, an in-vehicle device I/F 7660, and an in-vehicle network I/F 7680. Based on this, three-dimensional distance information between the vehicle and surrounding objects such as structures and people may be generated, and local map information including surrounding information of the current position of the vehicle may be generated. Furthermore, the microcomputer 7610 may predict dangers such as a vehicle collision, a pedestrian approaching, or entering a closed road, based on the acquired information, and generate a warning signal. The warning signal may be, for example, a signal for generating a warning sound or lighting a warning lamp.

The audio image output unit 7670 transmits an output signal of at least one of audio and image to an output device that can visually or audibly notify information to a passenger of the vehicle or to the outside of the vehicle. In the example of FIG. 17, an audio speaker 7710, a display section 7720, and an instrument panel 7730 are illustrated as output devices. Display unit 7720 may include, for example, at least one of an on-board display and a head-up display. The display section 7720 may have an AR (Augmented Reality) display function. The output device may be other devices other than these devices, such as headphones, a wearable device such as a glasses-type display worn by the passenger, a projector, or a lamp. When the output device is a display device, the display device displays results obtained from various processes performed by the microcomputer 7610 or information received from other control units in various formats such as text, images, tables, graphs, etc. Show it visually. Further, when the output device is an audio output device, the audio output device converts an audio signal consisting of reproduced audio data or acoustic data into an analog signal and audibly outputs the analog signal.

Note that in the example shown in FIG. 17, at least two control units connected via the communication network 7010 may be integrated as one control unit. Alternatively, each control unit may be composed of a plurality of control units. Furthermore, vehicle control system 7000 may include another control unit not shown. Furthermore, in the above description, some or all of the functions performed by one of the control units may be provided to another control unit. In other words, as long as information is transmitted and received via the communication network 7010, predetermined arithmetic processing may be performed by any one of the control units. Similarly, sensors or devices connected to any control unit may be connected to other control units, and multiple control units may send and receive detection information to and from each other via communication network 7010. .

Note that the present technology can have the following configuration.
(1) a light receiving section that receives a first optical signal including a plurality of wavelength bands;
a plurality of pixels that generate pixel signals by performing a convolution operation using autocorrelation or cross-correlation based on the first optical signal and the second optical signal;
an analog-to-digital converter that converts the pixel signal from analog to digital to generate a digital signal;
A photodetection device comprising: a Fourier transform processing section that performs Fourier transform processing on the digital signal.
(2) The photodetection device according to (1), wherein the first optical signal is a reflected optical signal obtained by reflecting an optical signal including a plurality of wavelength bands emitted by a light emitting section from an object.
(3) comprising an optical circulator that switches the propagation direction of the optical signal emitted by the light emitting section,
Switching the propagation direction of the optical signal emitted by the light emitting unit by the optical circulator and irradiating the object,
The photodetection device according to (2), wherein the light receiving section receives the first optical signal reflected by the object via the optical circulator.
(4) The photodetection device according to any one of (1) to (3), wherein the second optical signal is the first optical signal or a pulsed optical signal with a predetermined pulse width.
(5) The light receiving section is
a plurality of pixels each having a photoelectric conversion element;
a plurality of first optical waveguides that cause the first optical signal to enter the plurality of pixels at the same timing;
a plurality of second optical waveguides through which the second optical signal is input to the plurality of pixels while being sequentially shifted by a certain delay time;
The plurality of pixels output a pixel signal obtained by photoelectrically converting the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides and performing a convolution operation, ( 1) The photodetection device according to any one of (4).
(6) the second optical signal is the first optical signal,
The plurality of pixels generate the pixel signal by performing a convolution operation based on autocorrelation based on the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides. The photodetector according to (5).
(7) comprising a pulsed light generator that generates a pulsed light signal with a predetermined pulse width;
The second optical signal is the pulsed optical signal generated by the pulsed optical generator,
The plurality of pixels generate the pixel signal by performing a convolution operation based on cross-correlation based on the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides. The photodetector according to (5).
(8) The plurality of first optical waveguides individually adjust at least one of the optical path length, refractive index, or reflectance of the plurality of first optical waveguides to transmit the first optical signal at the same timing. The photodetection device according to any one of (5) to (7), in which the light is made incident on a plurality of pixels.
(9) The plurality of second optical waveguides are arranged such that at least one of the optical path length, refractive index, or reflectance of the plurality of second optical waveguides is individually adjusted so that the plurality of second optical waveguides are shifted by a certain delay time. The photodetection device according to any one of (5) to (7), wherein two optical signals are input to the plurality of pixels.
(10) The photodetection device according to any one of (1) to (9), wherein the first optical signal is an optical signal in an OFDM (Orthogonal Frequency Division Multiplexing) signal format.
(11) The first optical signal includes a plurality of subcarrier signals each having a different frequency band,
Among the plurality of subcarrier signals, at a frequency of a subcarrier signal where the signal strength reaches a peak value, the signal strength of two subcarrier signals adjacent to this subcarrier signal on the frequency axis is zero, (10) The photodetection device described in .
(12) comprising a spectrometer that spectrally separates an optical signal including a plurality of wavelength bands emitted from a light emitting unit into a plurality of spectral signals each having a different wavelength band;
A plurality of reflected spectral signals obtained by irradiating the plurality of spectral signals onto one or more objects and reflecting the plurality of spectral signals are optically coupled by the spectroscope to generate the first optical signal, which is received by the light receiving section. , (1) to (11).
(13) The photodetection device according to (12), wherein the plurality of spectral signals separated by the spectrometer propagate in different propagation directions within a predetermined area.
(14) comprising a scanning member that scans the plurality of spectral signals separated by the spectrometer in at least one direction;
The plurality of spectral signals scanned by the scanning member are irradiated onto the object, and the plurality of reflected spectral signals are optically coupled by the spectroscope to generate the first optical signal, and the plurality of reflected spectral signals are optically coupled by the spectrometer to generate the first optical signal, The photodetection device according to (12) or (13), which receives light at.
(15) comprising a refraction direction control member in which the spectroscope and the scanning member are integrated;
The light detection according to (14), wherein the refraction direction control member propagates the plurality of spectral signals in a two-dimensional direction by respectively differentiating the refraction directions of the plurality of spectral signals separated into wavelength bands included in the first optical signal. Device.
(16) The method according to any one of (1) to (15), further comprising a distance measuring unit that measures a distance to an object that reflects the first optical signal based on the result of performing the Fourier transform processing. The photodetection device described.
(17) The device according to any one of (1) to (15), further comprising a spectrum analysis unit that analyzes frequency components included in the first optical signal based on the result of the Fourier transform processing. Photodetection device.
(18) a light emitting unit that emits optical signals in a plurality of wavelength bands;
a light receiving unit that receives a first optical signal obtained by reflecting the optical signal emitted by the light emitting unit on an object;
a plurality of pixels that generate pixel signals by performing a convolution operation using autocorrelation or cross-correlation based on the first optical signal and the second optical signal;
an analog-to-digital converter that converts the pixel signal from analog to digital to generate a digital signal;
a Fourier transform processing unit that performs Fourier transform processing on the digital signal;
A distance measuring system comprising: a distance measuring section that measures a distance to the object based on a result of performing the Fourier transform processing.
(19) The distance measuring system according to (18), wherein the light emitting unit emits an optical signal in an OFDM signal format.

Aspects of the present disclosure are not limited to the individual embodiments described above, and include various modifications that can be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the contents described above. That is, various additions, changes, and partial deletions are possible without departing from the conceptual idea and spirit of the present disclosure derived from the content defined in the claims and equivalents thereof.

Reference Signs List 1, 1a interferometer, 2, 2a light source, 3 half mirror, 4 fixed mirror, 5 movable mirror, 6 light receiving section, 6a photoelectric conversion element, 7 optical waveguide, 8 optical variable delay element, 10a, 10b, 10c, 10d light Detection device, 11 Light receiving unit, 11a Photoelectric conversion element, 12 AD converter, 13 Fourier transform processing unit, 14 Pulse light generator, 15 Object, 16 Reflection member, 20 Distance measurement system, 20a Distance measurement system, 21 Circulator, 22 Spectrometer, 23 Scanning member, 24 Predetermined area, 31 Pixel chip, 32 Logic chip, 33 Pixel, 34 First optical waveguide, 35 Second optical waveguide, 36 DA converter, 37 Comparator, 38 Counter, 39 Connection part, 40 Connection section, 41 Distance measurement section, 42 Spectrum analysis section

Claims (19)

a light receiving unit that receives a first optical signal including a plurality of wavelength bands;
a plurality of pixels that generate pixel signals by performing a convolution operation using autocorrelation or cross-correlation based on the first optical signal and the second optical signal;
an analog-to-digital converter that converts the pixel signal from analog to digital to generate a digital signal;
A photodetection device comprising: a Fourier transform processing section that performs Fourier transform processing on the digital signal. The photodetection device according to claim 1, wherein the first optical signal is a reflected optical signal obtained by reflecting an optical signal including a plurality of wavelength bands emitted by a light emitting section from an object. comprising an optical circulator that switches the propagation direction of the optical signal emitted by the light emitting section,
Switching the propagation direction of the optical signal emitted by the light emitting unit by the optical circulator and irradiating the object,
The photodetection device according to claim 2, wherein the light receiving section receives the first optical signal reflected by the object via the optical circulator. The photodetection device according to claim 1, wherein the second optical signal is the first optical signal or a pulsed optical signal with a predetermined pulse width. The light receiving section is
a plurality of pixels each having a photoelectric conversion element;
a plurality of first optical waveguides that cause the first optical signal to enter the plurality of pixels at the same timing;
a plurality of second optical waveguides through which the second optical signal is input to the plurality of pixels while being sequentially shifted by a certain delay time;
The plurality of pixels output a pixel signal obtained by photoelectrically converting the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides and performing a convolution operation. Item 1. The photodetection device according to item 1. The second optical signal is the first optical signal,
The plurality of pixels generate the pixel signal by performing a convolution operation based on autocorrelation based on the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides. The photodetection device according to claim 5. Equipped with a pulsed light generator that generates a pulsed light signal with a predetermined pulse width,
The second optical signal is the pulsed optical signal generated by the pulsed optical generator,
The plurality of pixels generate the pixel signal by performing a convolution operation based on cross-correlation based on the light emitted from the plurality of first optical waveguides and the light emitted from the plurality of second optical waveguides. The photodetection device according to claim 5. The plurality of first optical waveguides individually adjust at least one of the optical path length, refractive index, or reflectance of the plurality of first optical waveguides, and transmit the first optical signal to the plurality of pixels at the same timing. The photodetecting device according to claim 5, wherein the photodetecting device is made to be incident on. The plurality of second optical waveguides individually adjust at least one of the optical path length, refractive index, or reflectance of the plurality of second optical waveguides so that the second optical signals are shifted by a certain delay time. The photodetection device according to claim 5, wherein the light is incident on the plurality of pixels. The photodetection device according to claim 1, wherein the first optical signal is an optical signal in an OFDM (Orthogonal Frequency Division Multiplexing) signal format. The first optical signal includes a plurality of subcarrier signals each having a different frequency band,
10. Among the plurality of subcarrier signals, at a frequency of a subcarrier signal at which the signal strength reaches a peak value, the signal strength of two subcarrier signals adjacent to this subcarrier signal on the frequency axis is zero. The photodetection device described in . Equipped with a spectrometer that separates an optical signal including multiple wavelength bands emitted from the light emitting unit into multiple spectral signals each having a different wavelength band,
A plurality of reflected spectral signals obtained by irradiating the plurality of spectral signals onto one or more objects and reflecting the plurality of spectral signals are optically coupled by the spectroscope to generate the first optical signal, which is received by the light receiving section. , The photodetection device according to claim 1. 13. The photodetection device according to claim 12, wherein the plurality of spectral signals separated by the spectrometer propagate in different propagation directions within a predetermined area. comprising a scanning member that scans the plurality of spectral signals separated by the spectroscope in at least one direction,
The plurality of spectral signals scanned by the scanning member are irradiated onto the object, and the plurality of reflected spectral signals are optically coupled by the spectroscope to generate the first optical signal, and the plurality of reflected spectral signals are optically coupled by the spectrometer to generate the first optical signal, The photodetection device according to claim 12, wherein the photodetection device receives light at. comprising a refraction direction control member that integrates the spectroscope and the scanning member,
15. The optical detection device according to claim 14, wherein the refraction direction control member propagates the plurality of spectral signals in a two-dimensional direction by respectively differentiating the refraction directions of the plurality of spectral signals separated for each wavelength band included in the first optical signal. Device. The photodetection device according to claim 1, further comprising a distance measuring section that measures a distance to an object that reflects the first optical signal based on a result of the Fourier transform processing. The photodetection device according to claim 1, further comprising a spectrum analysis section that analyzes frequency components included in the first optical signal based on a result of the Fourier transform processing. a light emitting unit that emits optical signals in multiple wavelength bands;
a light receiving unit that receives a first optical signal obtained by reflecting the optical signal emitted by the light emitting unit on an object;
a plurality of pixels that generate pixel signals by performing a convolution operation using autocorrelation or cross-correlation based on the first optical signal and the second optical signal;
an analog-to-digital converter that converts the pixel signal from analog to digital to generate a digital signal;
a Fourier transform processing unit that performs Fourier transform processing on the digital signal;
A distance measuring system comprising: a distance measuring unit that measures a distance to the object based on a result of performing the Fourier transform processing. The ranging system according to claim 18, wherein the light emitting unit emits an optical signal in an OFDM signal format.

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