JP2020139937A - Ranging device and electronic apparatus - Google Patents

Abstract

To provide: a ranging device that sufficiently irradiates, with light, a wider section of a ranging area from a light source and realizes exposure variation by automatic exposure control over the wider section of the ranging area; and an electronic device comprising the ranging device.SOLUTION: A ranging device 1 according to the present disclosure comprises: a light source 20 that emits light to a subject; a light detecting unit 30 that receives light reflected from the subject, the reflected light being based on the light emitted from the light source 20; and a control unit 40 that performs light exposure control depending on a distance between the ranging device 1 and the subject. An electronic device according to the present disclosure comprises the ranging device having the configuration.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to ranging devices and electronic devices.

As a distance measuring device (distance measuring device) for acquiring distance information (distance image information) to a subject, there is a device (sensor) using a ToF (Time of Flight) method (see, for example, Patent Document 1). ). The ToF method irradiates a subject (measurement object) with light from a light source, and detects the flight time of the light until the irradiated light is reflected by the subject and returned to the light detection unit to reach the subject. This is a method for measuring distance.

Japanese Unexamined Patent Publication No. 2004-294420

In the ToF type ranging device, automatic exposure (AE: Automatic Exposure) for the light source is controlled. In this AE control, in order to acquire a high-quality distance image (Deptth Map), the saturation threshold value is targeted, and the control is performed so that the maximum Confidence level can be acquired within a range not exceeding the saturation threshold value. Will be.

However, due to the permissible limit of power consumption and the setting limit of the laser output intensity of the light source, it is not possible to irradiate the entire section of the distance measurement range from the light source, for example, only in a part of the short distance. There was a situation in which exposure fluctuation due to automatic exposure control did not occur.

Therefore, the present disclosure is a distance measuring device that sufficiently irradiates a section having a wider range from a light source with light so that exposure fluctuation is caused by automatic exposure control over a section having a wider range. An object of the present invention is to provide an electronic device having the distance measuring device.

The ranging device of the present disclosure for achieving the above object is
A light source that illuminates the subject,
A photodetector that receives reflected light from the subject based on the light emitted from the light source, and
It is provided with a control unit that controls exposure according to the distance between the distance measuring device and the subject.

Further, the electronic device of the present disclosure for achieving the above object has a distance measuring device having the above configuration.

FIG. 1 is a conceptual diagram of a ToF type distance measuring system. FIG. 2 is a block diagram showing an example of the configuration of a ToF type ranging device to which the technique of the present disclosure is applied. FIG. 3 is a block diagram showing an example of the configuration of the photodetector. FIG. 4 is a circuit diagram showing an example of a pixel circuit configuration in the photodetector. FIG. 5 is a timing waveform diagram for explaining the calculation of the distance in the ToF type distance measuring device. FIG. 6 is a characteristic diagram showing the relationship between the signal value of the photodetector and the distance in the distance measuring device according to the first embodiment. FIG. 7 is a characteristic diagram showing the relationship between the signal value and the distance with respect to the reliability value of the IQ plane. FIG. 8 is a characteristic diagram showing the relationship between the exposure time and the distance, based on the case where a subject having a certain reflectance is placed at a distance of 10 [cm]. FIG. 9 is a diagram simply showing the AE control according to the conventional example. FIG. 10 is a diagram simply showing the calculation of the exposure time in the AE control according to the conventional example. FIG. 11 is a diagram simply showing the AE control according to the first embodiment of the present disclosure. FIG. 12 is a diagram simply showing the calculation process of the exposure time in the AE control according to the first embodiment of the present disclosure. FIG. 13 is an AE diagram of the AE control according to the first embodiment of the present disclosure. FIG. 14 is a characteristic diagram showing the characteristics of shot noise with respect to all signal values (average values). FIG. 15 is a characteristic diagram showing the characteristics of the reflected light noise offset with respect to all signal values (average values). FIG. 16 is a flowchart for explaining a specific processing flow of AE control according to the first embodiment of the present disclosure. FIG. 17 is a flowchart showing a flow of processing for calculating the light emission / exposure conditions of the next frame based on the RAW image data of the current frame and the light emission / exposure conditions. FIG. 18 is a timing chart showing an example of controlling the light emission time (exposure time). FIG. 19 is a timing chart showing an example of controlling the emission amplitude (emission intensity). FIG. 20 is an AE diagram of the AE control according to the second embodiment of the present disclosure. FIG. 21 is a flowchart illustrating a flow of AE control processing according to the second embodiment of the present disclosure. FIG. 22A is an external view of a smartphone according to a specific example of the electronic device of the present disclosure as viewed from the front side, and FIG. 22B is an external view as viewed from the back side.

Hereinafter, embodiments for carrying out the technique of the present disclosure (hereinafter, referred to as “embodiments”) will be described in detail with reference to the drawings. The technique of the present disclosure is not limited to the embodiment, and various numerical values and the like in the embodiment are examples. In the following description, the same reference numerals will be used for the same elements or elements having the same function, and duplicate description will be omitted. The explanation will be given in the following order.
1. 1. Description of the distance measuring device and electronic device of the present disclosure, and general description 2. ToF type ranging system 3. Distance measuring device to which the technology of the present disclosure is applied 3-1. System configuration 3-2. Configuration example of photodetector 3-3. Pixel circuit configuration example 4. About the dynamic of distance and confidence value (Confidence) 5. AE control according to the conventional example 6. AE control according to the first embodiment (example of AE control in distant view, near view, and super near view)
6-1. Exposure time calculation processing 6-2. About the mechanism of AE control according to the distance 6-3. Specific processing flow of AE control 6-4. Control of light emission / exposure conditions 7. AE control according to the second embodiment (a modified example of AE control in a super close view)
8. Modification example 9. Application example 10. Electronic device of the present disclosure (example of smartphone)
11. Configuration that can be taken by this disclosure

<Explanation of the ranging device and electronic device of the present disclosure, in general>
In the distance measuring device and the electronic device of the present disclosure, the control unit may be configured to perform exposure control based on the signal value output by the photodetector. Further, the control unit can be configured to control the light emission / exposure conditions of the next frame based on the image pickup data of the current frame output by the light detection unit and the light emission / exposure conditions.

In the distance measuring device and the electronic device of the present disclosure including the above-described preferable configuration, the control unit is configured to perform exposure control so as to maintain the specified first reliability value in the control of the relatively distant view. can do. Further, the control unit may be configured to perform exposure control so as to maintain a designated exposure time in the control of the relatively near view.

Further, in the ranging device and the electronic device of the present disclosure including the above-mentioned preferable configuration, the control unit separates the ambient light component incident on the photodetection unit and the reflected light component from the subject, and the reflected light. The configuration can be such that the component is the control target. Further, the control unit can be configured to estimate the ambient light component based on the image data output by the photodetector and separate the reflected light component and the ambient light component.

Further, in the distance measuring device and the electronic device of the present disclosure including the above-mentioned preferable configuration, the noise amount of the reflected light component is adaptively controlled by referring to the signal value output by the photodetector in the control unit. It can be configured to be.

Further, in the distance measuring device and the electronic device of the present disclosure including the above-described preferable configuration, a process of acquiring a distance image using the image data of the current frame including the distance information detected for each pixel of the photodetector is performed. It can be configured to include a distance measuring unit to perform.

Further, in the distance measuring device and the electronic device of the present disclosure including the above-mentioned preferable configuration, the exposure control is performed so as to maintain the specified second reliability value in the control of the relatively ultra-near view of the control unit. It can be configured to be performed. For ultra-near view, the distance to the subject (that is, the distance between the distance measuring device and the subject) can be set to such a short distance that the presence of the subject outside the distance measurement target causes the influence of scattered light. ..

<ToF distance measurement system>
FIG. 1 is a conceptual diagram of a ToF type distance measuring system. In the distance measuring device 1 according to this example, the ToF method is adopted as a measuring method for measuring the distance to the subject 10 which is a measurement target. The ToF method is a method of measuring the time until the light emitted toward the subject 10 is reflected by the subject 10 and returned. In order to realize the distance measurement by the ToF method, the distance measuring device 1 emits a light source 20 that emits light emitted toward the subject 10 (for example, a laser beam having a peak wavelength in the infrared wavelength region), and a subject. A light detection unit 30 for detecting the reflected light reflected by 10 and returned is provided.

<Distance measuring device to which the technology of the present disclosure is applied>
[System configuration]
FIG. 2 is a block diagram showing an example of the configuration of a ToF type distance measuring device to which the technique of the present disclosure is applied. The ranging device 1 according to the present application example (that is, the ranging device 1 of the present disclosure) performs exposure control based on the signal value output by the light detection unit 30 in addition to the light source 20 and the light detection unit 30. It includes a control unit 40 and a distance measuring unit 50. Then, the ToF type distance measuring device 1 according to this application example detects the distance information for each pixel of the photodetector 30, and acquires a highly accurate distance image (Deptth Map: depth map) in units of imaging frames. be able to.

In the distance measuring device 1 according to this application example, the light emitted from the light source 20 is reflected by the measurement object (subject), and the light flight time is determined based on the detection of the arrival phase difference of the reflected light to the light detection unit 30. It is an indirect ToF type distance image sensor that measures the distance from the distance measuring device 1 to the object to be measured by measuring.

Under the control of the AE control unit 40, the light source 20 irradiates light toward the object to be measured by repeating an on / off operation at a predetermined cycle. As the irradiation light of the light source 20, for example, near-infrared light in the vicinity of 850 nm is often used. The light detection unit 30 receives the light emitted from the light source 20 after being reflected by the object to be measured and returns, and detects the distance information for each pixel. The light detection unit 30 outputs the RAW image data of the current frame including the distance information detected for each pixel and the light emission / exposure setting information, and supplies the RAW image data to the AE control unit 40 and the distance measuring unit 50.

The AE control unit 40 has a configuration including a next frame light emission / exposure condition calculation unit 41 and a next frame light emission / exposure control unit 42. The next frame emission / exposure condition calculation unit 41 calculates the emission / exposure condition of the next frame based on the RAW image data of the current frame supplied from the light detection unit 30 and the emission / exposure setting information. The light emission / exposure conditions for the next frame are the light emission time and light emission intensity of the light source 20 when acquiring the distance image of the next frame, and the exposure time of the photodetector 30. The next frame emission / exposure control unit 42 detects the emission time, emission intensity, and light detection of the light source 20 of the next frame based on the emission / exposure conditions of the next frame calculated by the next frame emission / exposure condition calculation unit 41. The exposure time of the part 30 is controlled.

The distance measuring unit 50 has a configuration including a distance image calculation unit 51 for calculating a distance image. The distance image calculation unit 51 calculates the distance image by performing the calculation using the RAW image data of the current frame including the distance information detected for each pixel of the light detection unit 30, and the depth information which is the depth information and the depth information and It is output to the outside of the distance measuring device 1 as distance image information including the reliability value information which is the received light information. Here, the distance image is, for example, an image in which a distance value (depth / depth value) based on the distance information detected for each pixel is reflected in each pixel.

[Configuration example of photodetector]
Here, a specific configuration example of the photodetector 30 will be described with reference to FIG. FIG. 3 is a block diagram showing an example of the configuration of the photodetector 30.

The photodetector 30 has a laminated structure including a sensor chip 31 and a circuit chip 32 laminated to the sensor chip 31. In this laminated structure, the sensor chip 31 and the circuit chip 32 are electrically connected through a connecting portion (not shown) such as a via (VIA) or a Cu-Cu junction. Note that FIG. 3 illustrates a state in which the wiring of the sensor chip 31 and the wiring of the circuit chip 32 are electrically connected via the above-mentioned connection portion.

A pixel array unit 33 is formed on the sensor chip 31. The pixel array unit 33 includes a plurality of pixels 34 arranged in a matrix (array shape) in a two-dimensional grid pattern on the sensor chip 31. In the pixel array unit 33, each of the plurality of pixels 34 receives incident light (for example, near-infrared light), performs photoelectric conversion, and outputs an analog pixel signal. Two vertical signal lines VSL ₁ and VSL ₂ are wired in the pixel array unit 33 for each pixel row. Assuming that the number of pixel rows of the pixel array unit 33 is M (M is an integer), a total of (2 × M) vertical signal lines VSL are wired to the pixel array unit 33.

Each of the plurality of pixels 34 has a first tap A and a second tap B (details thereof will be described later). Of the two vertical signal lines VSL ₁ and VSL ₂ , the vertical signal line VSL ₁ outputs an analog pixel signal AIN _P1 based on the charge of the first tap A of the pixel 34 of the corresponding pixel sequence. Further, an analog pixel signal AIN _P2 based on the charge of the second tap B of the pixel 34 of the corresponding pixel string is output to the vertical signal line VSL ₂ . The analog pixel signals AIN _P1 and AIN _P2 will be described later.

A row selection unit 35, a column signal processing unit 36, an output circuit unit 37, and a timing control unit 38 are arranged on the circuit chip 32. The row selection unit 35 drives each pixel 34 of the pixel array unit 33 in units of pixel rows, and outputs pixel signals AIN _P1 and AIN _P2 . Under the drive of the row selection unit 35, the analog pixel signals AIN _P1 and AIN _P2 output from the pixel 34 of the selected row are supplied to the column signal processing unit 36 through the _two vertical signal lines VSL ₁ and VSL _2. To.

The column signal processing unit 36 has a configuration having, for example, a plurality of analog-to-digital converters (ADCs) 39 provided for each pixel array corresponding to the pixel array of the pixel array unit 33. The analog-to-digital converter 39 performs analog-to-digital conversion processing on the analog pixel signals AIN _P1 and AIN _P2 supplied through the vertical signal lines VSL ₁ and VSL ₂ , and outputs them to the output circuit unit 37. The output circuit unit 37 executes CDS (Correlated Double Sampling) processing or the like on the digitized pixel signals AIN _P1 and AIN _P2 output from the column signal processing unit 36, and outside the circuit chip 32. Output to.

The timing control unit 38 generates various timing signals, clock signals, control signals, etc., and drives the row selection unit 35, the column signal processing unit 36, the output circuit unit 37, etc. based on these signals. Take control.

[Example of pixel circuit configuration]
FIG. 4 is a circuit diagram showing an example of the circuit configuration of the pixel 34 in the photodetector 30.

The pixel 34 according to this example has, for example, a photodiode 341 as a photoelectric conversion unit. In addition to the photodiode 341, the pixel 34 includes overflow transistors 342, two transfer transistors 343, 344, two reset transistors 345, 346, two floating diffusion layers 347, 348, two amplification transistors 349, 350, and two. It has a configuration having one selection transistor 351 and 352. The two floating diffusion layers 347 and 348 correspond to the first and second taps A and B (hereinafter, may be simply referred to as "tap A and B") shown in FIG. 3 described above.

The photodiode 341 photoelectrically converts the received light to generate an electric charge. The photodiode 341 may have, for example, a back-illuminated pixel structure that captures light emitted from the back surface side of the substrate. However, the pixel structure is not limited to the back-illuminated pixel structure, and a surface-irradiated pixel structure that captures the light emitted from the surface side of the substrate can also be used.

The overflow transistor 342 is connected between the cathode electrode of the photodiode 341 and the power supply line of the power supply voltage V _DD , and has a function of resetting the photodiode 341. Specifically, the overflow transistor 342 becomes conductive in response to the overflow gate signal OFG supplied from the row selection unit 35, so that the electric charge of the photodiode 341 is sequentially discharged to the power supply line of the power supply voltage V _DD. To do.

The two transfer transistors 343 and 344 are connected between the cathode electrode of the photodiode 341 and each of the two floating diffusion layers 347 and 348 (tap A, B). Then, the transfer transistors 343 and 344 are brought into a conductive state in response to the transfer signal TRG supplied from the row selection unit 35, so that the electric charges generated by the photodiode 341 are sequentially transferred to the floating diffusion layers 347 and 348, respectively. Transfer to.

The floating diffusion layers 347 and 348 corresponding to the first and second taps A and B accumulate the electric charge transferred from the photodiode 341 and convert it into a voltage signal having a voltage value corresponding to the amount of the electric charge. Generates pixel signals AIN _P1 and AIN _P2 .

The two reset transistors 345 and 346 are connected between each of the two floating diffusion layers 347 and 348 and the power supply line of the power supply voltage V _DD . Then, the reset transistors 345 and 346 are brought into a conductive state in response to the reset signal RST supplied from the row selection unit 35, so that charges are extracted from each of the floating diffusion layers 347 and 348 to initialize the charge amount. To do.

The two amplification transistors 349 and 350 are connected between the power supply line of the power supply voltage V _DD and each of the two selection transistors 351 and 352, and are converted from electric charge to voltage by the floating diffusion layers 347 and 348, respectively. Each voltage signal is amplified.

The two selection transistors 351 and 352 are connected between the two amplification transistors 349 and 350 and the vertical signal lines VSL ₁ and VSL ₂ , respectively. Then, the selection transistors 351 and 352 enter a conductive state in response to the selection signal SEL supplied from the row selection unit 35, so that the voltage signals amplified by the amplification transistors 349 and 350 are converted into analog pixel signals. Output to _two vertical signal lines VSL ₁ and VSL ₂ as AIN _P1 and AIN _P2 .

The two vertical signal lines VSL ₁ and VSL ₂ are connected to the input end of one analog-to-digital converter 39 in the column signal processing unit 36 for each pixel row, and are output from the pixel 34 for each pixel row. The analog pixel signals AIN _P1 and AIN _P2 are transmitted to the analog-to-digital converter 39.

The circuit configuration of the pixel 34 is not limited to the circuit configuration illustrated in FIG. 3 as long as it can generate analog pixel signals AIN _P1 and AIN _P2 by photoelectric conversion.

Here, the calculation of the distance by the ToF method will be described with reference to FIG. FIG. 5 is a timing waveform diagram for explaining the calculation of the distance in the ToF type distance measuring device 1. The light source 20 and the light detection unit 30 in the ToF type distance measuring device 1 operate at the timing shown in the timing waveform diagram of FIG.

Light source 20, under control by the AE control unit 40 for a predetermined period, for example, only during the period of the pulse emission time T _p, for irradiating light to the object of measurement. The irradiation light emitted from the light source 20 is reflected by the object to be measured and returned. This reflected light (active light) is received by the photodiode 341. The time for the photodiode 341 to receive the reflected light after the irradiation of the irradiation light to the measurement object is started, that is, the light flight time is the time corresponding to the distance from the distance measuring device 1 to the measurement object. ..

In FIG. 4, the photodiode 341 receives the reflected light from the object to be measured for a period of pulse emission time T _p from the time when the irradiation of the irradiation light is started. At this time, as the light received by the photodiode 341, the light radiated to the object to be measured is reflected by an object, the atmosphere, or the like in addition to the reflected light (active light) that is reflected by the object to be measured and returned.・ Scattered ambient light is also included.

At the time of one light reception, the charge photoelectrically converted by the photodiode 341 is transferred to the tap A (floating diffusion layer 347) and accumulated. Then, a signal n ₀ of a voltage value corresponding to the amount of electric charge accumulated in the floating diffusion layer 347 is acquired from the tap A. When the accumulation timing of the tap A is completed, the charge photoelectrically converted by the photodiode 341 is transferred to the tap B (suspended diffusion layer 348) and accumulated. Then, a signal n ₁ having a voltage value corresponding to the amount of electric charge accumulated in the floating diffusion layer 348 is acquired from the tap B.

In this way, the tap A and the tap B are driven by 180 degrees out of phase of the accumulation timing (driving with the phases completely reversed), so that the signal n ₀ and the signal n ₁ are acquired, respectively. To. Then, such driving is repeated a plurality of times, and the signal n ₀ and the signal n ₁ are accumulated and integrated to acquire the accumulated signal N ₀ and the accumulated signal N ₁ , respectively.

For example, for one pixel 34, light reception is performed twice in one phase, and signals of 0 degree, 90 degree, 180 degree, and 270 degree are accumulated in tap A and tap B four times each. The distance D from the distance measuring device 1 to the object to be measured is calculated based on the stored signal N ₀ and the stored signal N ₁ acquired in this way.

In addition to the components of the reflected light (active light) that is reflected by the object to be measured and returned, the stored signal N ₀ and the stored signal N ₁ include ambient light that is reflected and scattered by an object or the atmosphere. Ingredients are also included. Therefore, in the above-mentioned operation, in order to remove the influence of the component of the ambient light and leave the component of the reflected light (active light), the signal n ₂ based on the ambient light is also accumulated and integrated, and the environment. The accumulated signal N ₂ for the light component is acquired.

Using the storage signal N ₀ and the storage signal N ₁ including the ambient light component and the storage signal N ₂ for the ambient light component obtained in this way, the following equations (1) and (2) are used. The distance D from the distance measuring device 1 to the object to be measured can be calculated by the arithmetic processing based on the above.

In the formulas (1) and (2), D represents the distance from the distance measuring device 1 to the object to be measured, c represents the speed of light, and T _p represents the pulse emission time.

The distance image calculation unit 51 shown in FIG. 2 is output from the photodetection unit 30 by using the storage signal N ₀ and the storage signal N ₁ including the ambient light component and the storage signal N ₂ for the ambient light component. The distance D from the distance measuring device 1 to the object to be measured is calculated by the arithmetic processing based on the above equations (1) and (2), and is output as the distance image information. As the distance image information, for example, image information colored with a color having a density corresponding to the distance D can be exemplified. Although the calculated distance D is output as the distance image information here, the calculated distance D may be output as the distance information as it is.

<Dynamic distance and confidence>
By the way, it is known that the light intensity from a point light source is attenuated in inverse proportion to the square of the distance from the point light source. In the distance measuring device 1 according to the present embodiment, the relationship between the signal value of the photodetector 30 and the distance in the case of 0-degree, 90-degree, 180-degree, and 270-degree signals stored in the tap A and the tap B is shown. Shown in 6. In FIG. 6, the broken line represents a signal of 0 degrees, the dotted line represents a signal of 90 degrees, the alternate long and short dash line represents a signal of 180 degrees, and the solid line represents a signal of 270 degrees. As is clear from this characteristic diagram, it can be seen that the signal value of the photodetector 30 based on the light intensity is attenuated in inverse proportion to the square of the distance.

In a simple model, the signal value is expressed by:
Signal value = Amplitude of light emitting source x Exposure time (= Light emission time) x Reflectance of subject x Constant Here, the constant is a conversion coefficient of other (other than amplitude of light emitting source, exposure time, and reflectance of subject). is there.
However, the exposure time to be controlled by the AE and the signal value have a linear relationship.

FIG. 7 shows the relationship between the signal value and the distance with respect to the confidence value (Confidence) of the IQ plane calculated from the signals of 0 degrees, 90 degrees, 180 degrees, and 270 degrees of tap A and tap B. Here, the "reliability value" is the light reception information of the photodetector 30, and the light emitted (irradiated) from the light source 20 is reflected by the measurement object (subject) and returned to the photodetector 30. It is the amount (degree) of reflected light (active light). In FIG. 7, the solid line represents the confidence value, the dotted line represents the I value (= dm ₀ −dm ₂ ), and the broken line represents the Q value (= dm ₁ −dm ₃ ). The details of dm will be described later.

FIG. 8 shows the relationship of the exposure time (emission time) with respect to the distance based on the case where the subject (measurement object) having a certain reflectance is placed at a distance of 10 [cm]. In the characteristic diagram of FIG. 8, for example, when a subject having the same reflectance is gradually moved away under an exposure time of 1000 [μsec], irradiation for a time of about 2500 [μsec] is performed at a distance of 50 [cm]. Indicates that it is necessary.

In the characteristic diagram of FIG. 8, the ratio of the confidence value to the distance (Confidence ratio) is 31.6 [cm], which is 1/1000 times. This is the same as the reliability value obtained when a subject with a certain reflectance is placed at a distance of 10 [cm] and the exposure time is set to 1 [msec], and a subject with the same reflectance is set at a distance of 31.6 [cm]. It means that the reliability value obtained when the exposure time is set to 1000 [msec] is the same.

<AE control according to the conventional example>
In the AE control according to the conventional example, in order to always obtain the maximum SN ratio, the exposure time for achieving a non-saturated state (a state as close as possible to the saturation threshold) is calculated, and the exposure time is set to the exposure time. I try to control based on. FIG. 9 briefly shows the AE control according to the conventional example. In the AE control according to the conventional example, the reflected light (active light) + ambient light (ambient light) is set as the control target, and if the control target of the current frame is lower than the saturation threshold, the control target of the next frame is unlimitedly limited to the saturation threshold. Control to bring them closer is performed.

FIG. 10 briefly shows the calculation of the exposure time in the AE control according to the conventional example. In FIG. 10, cm is the intersection of the smaller tap A and tap B (tap B in this example) with respect to the reflected light (active light) and the ambient light (ambient light), and | dm | is the reflection. It is the absolute value of the difference between the larger and smaller taps A and B with respect to light (active light). Further, the saturation threshold (Saturation Threshold), the target control level (target_controllable_level), the target control gap (target_controllable_gap), and the dark offset (dark_offset) are parameters, and the intersection cm, the absolute value of the difference | dm |, the reflected light. (Active light) and ambient light (ambient light) are observed values. Where the target control gap (target_controllable_gap) is
target_controllable_gap ＝ target_controllable_level−dark_offset
Is.

<AE control according to the first embodiment>
The ToF type ranging device 1 can be mounted on an electronic device having a camera function, for example, a mobile device such as a smartphone, a digital camera, a tablet, or a personal computer. Then, in the AE control of the distance measuring device 1, in order to acquire a high-quality distance image, the saturation threshold value is targeted and controlled so that the maximum confidence value (Confidence) level can be acquired within a range not exceeding the saturation threshold value. The purpose is to do.

However, especially in the distance measuring device mounted on the mobile device, the irradiation time of the laser beam cannot be set long or the laser output intensity of the light source 20 can be set due to the influence of the power consumption tolerance limit and the camera shake of the mobile device. Due to a limit or the like, it is not possible to irradiate the entire section of the distance measuring range from the light source 20 with light. As a result, in the AE control according to the conventional example, the AE control is effective only in a part of the distance measuring range, for example, a part of the short distance (that is, the exposure fluctuation due to the AE control does not occur). there were.

Therefore, in the AE control according to the first embodiment of the present disclosure, light is sufficiently irradiated from the light source 20 to a wider section of the ranging range, and the AE control is effective over the wider section of the ranging range (). That is, the exposure fluctuation due to the AE control occurs). More specifically, in the AE control according to the first embodiment, the amount of reflected light is reduced by controlling the reflected light (active light) portion for the purpose of always maintaining the specified confidence value (Confidence). The exposure time for keeping the exposure constant is calculated, and the control is performed based on the exposure time.

The AE control according to the first embodiment of the present disclosure is briefly shown in FIG. When the reflected light portion is to be controlled, it is necessary to separate the reflected light component and the ambient light component. By turning off the light source 20 and taking an image at the same exposure time, the ambient light components can be individually acquired. In the first embodiment, a method of estimating the ambient light component based on the RAW image data of the photodetector 30 and separating the reflected light component and the ambient light component is adopted. However, the method is not limited to this method.

(About the calculation process of exposure time)
FIG. 12 briefly shows the calculation process of the exposure time in the AE control according to the first embodiment of the present disclosure. In FIG. 12, cm is the intersection of the smaller tap A and tap B (tap B in this example) with respect to reflected light and ambient light, and | dm | is tap A and tap B with respect to reflected light. It is the absolute value of the difference between the larger and smaller of. In addition, saturation threshold (Saturation Threshold), target control level (target_controllable_level), target control gap (target_controllable_gap), reflected light noise offset (active_noise_offset), target reflected light level (target_active_level), and dark offset (dark_offset) are parameters. Yes, the common part cm, the absolute value of the difference | dm |, the reflected light, and the ambient light are observed values. Where the target control gap (target_controllable_gap) is
target_controllable_gap ＝ target_controllable_level−dark_offset
Is.

Here, the difference dm between the larger tap A and the smaller tap B will be described. The signal values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees of tap A are set to TapA ₀ , TapA ₁ , TapA ₂ , and TapA _3, and the signal values of tap B at 0 degrees, 90 degrees, 180 degrees, and 270 degrees are TapB. _{When 0} , TapB ₁ , TapB ₂ , TapB ₃
dm ₀ = TapA ₀ −TapB ₀
dm ₁ = TapA _{1 −} TapB ₁
dm ₂ = TapA _2- TapB ₂
dm ₃ = TapA _3- TapB ₃
It can be expressed as.

Based on the above dm ₀ , dm ₁ , dm ₂ , dm ₃
I = dm ₀ −dm ₂
Find the I value from the formula of
Q = dm ₁ − dm ₃
Obtain the Q value from the formula of and take it on the Y axis to create an IQ plane (see FIG. 7). FIG. 7 shows the relationship between the signal value and the distance with respect to the reliability value of the IQ plane calculated from the signals of 0 degree, 90 degree, 180 degree, and 270 degree of tap A and tap B. Also, regarding the reliability value
Confidence value = | I | + | Q |
It can be expressed as.

In calculating the exposure time so that the amount of reflected light is always constant, a measured value (measured_active) corresponding to the difference dm between the larger and smaller taps A and B is obtained. As for the measured value (measured_active) corresponding to the difference dm, the average value of the difference dm or the average value of the reliability values in a predetermined region of interest (ROI) can be obtained as the measured value. Then, using the obtained measured values and parameters such as the target control gap (target_controllable_gap), the target reflected light level (target_active_level), and the reflected light noise offset (active_noise_offset), the next frame is based on a predetermined calculation formula. The integration coefficient is obtained, and the exposure time (next_exposure_time) of the next frame is obtained from the integration coefficient and the exposure time (current_exposure_time) of the current frame.

(About the mechanism of AE control according to the distance)
FIG. 13 is an AE diagram of the AE control according to the first embodiment of the present disclosure. In the first embodiment, the control is divided according to the distance between the distance measuring device 1 and the subject (measurement object), and the control according to the distance is largely the section A. , Section B, and section C are divided into three sections. The section A is a control in the case of a so-called distant view, in which the distance between the distance measuring device 1 and the subject is relatively long. The section B is a control in the case of a so-called near view, in which the distance between the distance measuring device 1 and the subject is relatively short. The section C is a control in the case of a so-called ultra-near view in which the distance between the distance measuring device 1 and the subject is very short.

In the AE diagram of FIG. 13, the vertical axis represents the exposure time of the next frame, and the horizontal axis represents the signal value [LSB] of the maximum tap maxtap of the photodetector 30. The maximum tap max tap is
maxtap = max {cm [i] + | dm [i] |}
Given in. Here, i = 0 to 3. Further, as is clear from the characteristic diagram of FIG. 6, since the signal value of the photodetector 30 based on the light intensity is attenuated in inverse proportion to the square of the distance, the signal value [LSB] on the horizontal axis is measured. This corresponds to the distance between the distance device 1 and the subject. Then, in the AE control according to the first embodiment, the optimum control value (exposure time) for acquiring the depth information (depth information) in the distance measuring unit 50 is calculated based on the signal value output by the light detection unit 30. The exposure is controlled.

In the AE control according to the first embodiment, in the control of the section A (distant view), the first confidence value (target reflected light level (target_active_level) -reflected light noise offset (active_noise_offset) specified as the control parameter (threshold value) is maintained. , Processing is performed to obtain a distance image (Deepth Map: depth map) with the minimum SN ratio. Specifically, the characteristic of signal value-exposure time in section A is given by the formula shown in FIG. The control is performed so that the gradient slop is a straight line (linear).

In the control of the section B (near view), processing is performed to maintain a designated typical exposure time and obtain a distance image having a high SN ratio. Specifically, the straight line of the gradient slop obtained in the section A (the straight line indicated by the dotted line in the figure) is changed to a typical exposure time, and the exposure time is controlled to be constant with respect to the signal value (distance). Is done. As a result, it is possible to secure a reliability value equal to or higher than a specified minimum value for an application in which a near view is important.

In the control of the section C (ultra-near view), saturated pixels exceeding the saturation threshold value start to appear. Therefore, as in the case of the AE control according to the conventional example, the exposure time is reduced according to the saturation pixel ratio. Here, the "saturated pixel ratio" is the ratio of saturated pixels exceeding the saturation threshold to the total number of pixels in a predetermined region of interest (ROI) to be optimized.

Further, in the AE control according to the first embodiment, the noise amount of the reflected light (active light) component is adaptively controlled with reference to the signal value output by the photodetector 30. Specifically, in the AE control according to the first embodiment, it is assumed that the noise amount of the reflected light (active light) component has a linear relationship with the shot noise of the light detection unit 30, and the reflected light shown in FIG. The noise offset (active_noise_offset) is controlled adaptively. FIG. 14 shows a characteristic diagram of shot noise with respect to all signal values (average value), and FIG. 15 shows a characteristic diagram of reflected light noise offset with respect to all signal values (average value).

In this adaptive control of the reflected light noise offset, as shown in FIG. 15, the reflected light noise offset (active_noise_offset [0]) at the time of dark offset and the reflected light noise offset (active_noise_offset [1]) at the time corresponding to the saturation threshold are used. ) And is set, and control is performed to linearly transition the reflected light noise offset between the two. By performing adaptive control of the reflected light noise offset in this way, even if the noise magnitude differs between indoors and outdoors, good AE control can be performed without being affected by the noise magnitude. Can be done.

As is clear from the above description, according to the AE control according to the first embodiment of the present disclosure, light is sufficiently irradiated from the light source 20 to a wider section of the ranging range, and the distance measuring range is increased. AE control will be effective over a wide section. Here, "the AE control is effective" means the following.
-By controlling the exposure time (light emission time), the confidence value (Confidence) becomes constant.
-It can be controlled so as not to exceed the saturation threshold.
That is, according to the AE control according to the first embodiment of the present disclosure, there is a possibility that the saturation threshold value may be exceeded in a certain scene (conditions such as the distance to the subject, the shape of the subject, the reflectance of the subject, the amount of ambient light, etc.). Even if there is, it can be controlled so as not to exceed the saturation threshold.

Further, according to the AE control according to the first embodiment of the present disclosure, the near view is controlled separately from the distant view, so that the distance measuring device 1 can be used as a mobile device such as a smartphone, as will be described later. When it is installed, it is possible to obtain the effect that the SN ratio can be maintained for an important distance measuring section in a gesture application or the like.

(About the specific processing flow of AE control)
A specific processing flow of AE control according to the first embodiment of the present disclosure will be described with reference to the flowchart of FIG. The AE control process exemplified here is the process in the AE control unit 40 shown in FIG. In FIG. 2, the AE control unit 40 is composed of the next frame emission / exposure condition calculation unit 41 and the next frame emission / exposure control unit 42, but the next frame emission / exposure condition calculation unit 41 and the next frame emission / exposure control Each function of the unit 42 may be realized by a processor.

In the following, in the case where each function of the next frame light emission / exposure condition calculation unit 41 and the next frame light emission / exposure control unit 42 is realized by a processor, AE control is performed under the control of the processor constituting the AE control unit 40. Process is to be executed.

The processor constituting the AE control unit 40 (hereinafter, simply referred to as “processor”) determines whether or not the AE control process is completed (step S11), and if not (NO in S11), the current frame The RAW imaging data and the light emission / exposure conditions are acquired from the photodetector 30 (step S12). The RAW imaging data of the current frame and the light emission / exposure conditions are the light emission time and emission intensity of the light source 20 at the time of imaging of the current frame, and the exposure time of the photodetector 30.

Next, the processor calculates the light emission / exposure condition of the next frame based on the acquired RAW image data of the current frame and the light emission / exposure condition (step S13). The light emission / exposure conditions of the next frame are the light emission time and light emission intensity of the light source 20 at the time of imaging of the next frame, and the exposure time of the photodetector 30. The details of the specific processing in step S13 will be described later.

Next, the processor notifies the light source 20 of the light emission / exposure condition of the next frame calculated in the process of step S13 (step S14), returns to step S11, and performs the processes from step S11 to step S14 in step S11. In the process of, the AE control process is repeatedly executed until it is determined that the process is completed. Then, if the AE control process is completed (YES in S11) in the process of step S11, the processor ends the series of processes described above for the AE control.

Next, the flowchart of FIG. 17 is shown for details of the specific process of step S13, that is, the process of calculating the light emission / exposure condition of the next frame based on the RAW image data of the current frame and the light emission / exposure condition. It will be described using.

The processor calculates the saturated pixel ratio, which is the ratio of saturated pixels to the total number of pixels in a predetermined region of interest (ROI) to be optimized, based on the RAW imaging data of the current frame acquired in the process of step S12 of FIG. (Step S21). Next, the processor determines whether or not the saturated pixel ratio exceeds the preset ratio (step S22), and if it determines that the saturation pixel ratio exceeds (YES in S22), the light emission / exposure condition of the next frame at the time of saturation is determined. Calculate (step S23). When the saturated pixel ratio exceeds a preset ratio, that is, when the number of saturated pixels is relatively large, the linearity is lost and it becomes difficult to calculate the optimum exposure time. Therefore, in step S23, the exposure time is simply shortened. Processing is performed.

When the processor determines that the saturation pixel ratio does not exceed the preset ratio (NO in S22), the light emission of the next frame is emitted based on the emission / exposure conditions of the current frame acquired in the process of step S12 of FIG. The exposure conditions are calculated (step S24). In the process of step S24, the optimum exposure time (emission time) is calculated and the optimum exposure time (emission time) is calculated based on the processes described in the above-mentioned "exposure time calculation process" and "AE control mechanism according to distance". AE control is performed according to the distance.

After the process of step S23 or the process of step S24, the processor returns to the flow of FIG. 16 and proceeds to the process of step S14.

(Control of light emission / exposure conditions)
The following two can be exemplified as specific examples of controlling the light emission / exposure conditions.
-Example of controlling the light emission time (exposure time) FIG. 18 is a timing chart showing an example of controlling the light emission time (exposure time). In this control example, as shown in FIG. 18, the light emission / exposure conditions can be controlled by controlling the light emission interval.
-Example of controlling the emission amplitude (emission intensity) FIG. 19 is a timing chart showing an example of controlling the emission amplitude (emission intensity). In this control example, as shown in FIG. 19, the emission / exposure conditions can be controlled by controlling the emission amplitude, that is, the emission intensity.

<AE control according to the second embodiment>
By the way, in the ToF type distance measuring device, when an object other than the distance measurement target (for example, an obstacle) exists at a very short distance and the distance measurement is performed, the subject to be distance measurement exists. Even in a region that does not exist, scattered light from an object that is not subject to distance measurement at a short distance may be received, and erroneous detection may occur due to the scattered light.

Therefore, in the second embodiment, even in an environment where an object other than the distance measurement target exists at an extremely short distance (for example, a distance of about 20 cm) where the influence of scattered light is generated, the subject to be distance-measured. And the background thereof, AE control that enables accurate distance measurement is performed. Specifically, in the AE control according to the second embodiment, in the control of the ultra-near view, the distance to the subject is an extremely short distance such that the influence of scattered light is generated by the presence of an object other than the distance measurement target. , The upper limit of the reliability value is defined as the second reliability value (control parameter / threshold value), and the AE control is performed so as to maintain the second reliability value.

Here, the second reliability value as the control parameter / threshold value is, as an example, a higher reliability value than the first reliability value in the case of distant view control in the AE control according to the first embodiment (first reliability value). <Second confidence value). Then, in the control of the ultra-near view, the control is reflected in the exposure time (or emission intensity) so as to suppress the amount of scattered light from an object that is not subject to distance measurement at a short distance. FIG. 20 shows an AE diagram of the AE control according to the second embodiment.

Here, it is assumed that a higher reliability value than the first reliability value is specified as the second reliability value, but depending on the use case (for example, when long-distance control is not required), the first reliability value = first. 2 It may be a reliable value.

The flow of the AE control process according to the second embodiment will be described with reference to the flowchart of FIG. The AE control process exemplified here is the process in the AE control unit 40 shown in FIG. In the following, in the case of a configuration in which the function of the AE control unit 40 is realized by a processor, the AE control process according to the second embodiment is executed under the control of the processor constituting the AE control unit 40. ..

The processor (hereinafter, simply referred to as “processor”) constituting the AE control unit 40 first calculates the exposure time of the next frame (step S31), and then the calculated exposure time is a designated representative value (typical). ) Is not included (step S32).

When the processor determines that the exposure time calculated in step S31 is equal to or longer than the representative value (NO in S32), the processor adopts the calculation result in step S31 as the exposure time of the next frame (step S33). This control is the control of the section A (distant view). Then, by controlling the distant view, processing is performed to maintain the first confidence value specified as the control parameter (threshold value) and obtain a distance image having the minimum SN ratio. Specifically, control is performed so that the characteristic of the signal value-exposure time in the section A becomes a straight line of the gradient slop given by the equation shown in FIG.

If the processor determines that the exposure time calculated in step S31 is less than the representative value (YES in S32), then whether the confidence value is equal to or greater than the threshold value (= second confidence value) which is a control parameter. It is determined whether or not (step S34).

When the processor determines that the confidence value is below the threshold value (NO in S34), the processor applies the representative value to the exposure time of the next frame (step S35). This control is the control of the section B (near view). By controlling this near view, processing for maintaining the exposure time specified as a representative value and obtaining a distance image with a high SN ratio, that is, processing for achieving a constant exposure time with respect to the signal value (distance) is performed. Be told. As a result, it is possible to secure a reliability value equal to or higher than a specified minimum value for an application in which a near view is important.

When the processor determines that the reliability value is equal to or greater than the threshold value (YES in S34), the processor corrects the exposure time of the next frame, specifically, controls to shorten the exposure time (step S36). This control is the control of the section C', that is, the control of the super near view. For the ultra-near view, the distance to the subject (that is, the distance between the distance measuring device and the subject) can be set to such a short distance that the presence of an object not subject to distance measurement causes the influence of scattered light. ..

Then, in the control of the ultra-near view, the exposure control for shortening the exposure time again is performed so as to maintain the second confidence value specified as the control parameter (threshold value). The gradient slop of the exposure time in the case of the section C'(super near view) is the same as the gradient slop in the case of the control of the section A (distant view). By controlling this ultra-near view, it is possible to suppress the amount of scattered light from the object in an environment where an object other than the distance measurement target exists at an extremely short distance where the influence of the scattered light is generated.

In an environment where an object not subject to distance measurement exists nearby, it is affected by scattered light, but the relative intensity of scattered light decreases by appropriately controlling the reliability value of the entire screen. Therefore, in a super-near view where the influence of scattered light is generated by the presence of an object not subject to distance measurement, the upper limit of the reliability value is defined as the second reliability value, and AE control is performed so as to maintain the second reliability value. By doing so, it is possible to perform accurate distance measurement on the subject and its background to be distanced while suppressing the influence of scattered light from an object not subject to distance measurement.

The AE control according to the second embodiment described above is executed based on the information of one imaging frame. Normally, it is difficult to determine from the information of one imaging frame whether scattered light is generated or whether the subject actually exists in the environment where scattered light is generated, and multiple images are taken. Or, a scattered light removal filter will be used.

According to the AE control according to the second embodiment, a plurality of images are taken or a scattered light removal filter is used even in a super close view in which the influence of scattered light is generated by the presence of an object not subject to distance measurement. Without this, it is possible to maintain appropriate distance measurement performance while suppressing the influence of scattered light from an object not subject to distance measurement. Except for the ultra-near view, the longer the exposure time, the more the SN ratio can be secured.

<Modification example>
The technique of the present disclosure has been described above based on the preferred embodiment, but the technique of the present disclosure is not limited to the embodiment. The configuration and structure of the distance measuring device described in each of the above embodiments are examples, and can be changed as appropriate. For example, in the first embodiment, when the control is divided according to the distance between the distance measuring device 1 and the subject (measurement object), the control is limited to three sections of distant view, near view, and super near view. It is not something that can be done. Specifically, it is possible to control two sections of a distant view and a near view, or it is possible to further subdivide the distant view and the near view to control four or more sections.

<Application example>
In each of the above embodiments, the case where the distance measuring device of the present disclosure is used as a means for acquiring a distance image (depth map) has been described as an example, but it is not only used as a means for acquiring a distance image, but also. It can be applied to autofocus that automatically adjusts the focus of the camera.

<Electronic device of this disclosure>
The distance measuring device of the present disclosure described above can be used as a distance measuring device mounted on various electronic devices. Examples of electronic devices equipped with a distance measuring device include mobile devices such as smartphones, digital cameras, tablets, and personal computers. However, it is not limited to mobile devices. Here, a smartphone will be illustrated as a specific example of an electronic device (electronic device of the present disclosure) that can be equipped with the distance measuring device of the present disclosure.

FIG. 22A shows an external view of a smartphone according to a specific example of the electronic device of the present disclosure as seen from the front side, and FIG. 22B shows an external view as seen from the back side. The smartphone 100 according to this specific example includes a display unit 120 on the front side of the housing 110. Further, the smartphone 100 is provided with an image pickup unit 130 on the upper side of the back surface side of the housing 110, for example.

The distance measuring device 1 according to the first embodiment or the second embodiment of the present disclosure described above can be mounted on, for example, a smartphone 100 which is an example of a mobile device having the above configuration. In this case, the light source 20 and the light detection unit 30 of the distance measuring device 1 can be arranged in the vicinity of the imaging unit 130, for example, as shown in FIG. 22B. However, the arrangement example of the light source 20 and the light detection unit 30 shown in FIG. 22B is an example, and is not limited to this arrangement example.

As described above, the smartphone 100 according to the specific example is manufactured by mounting the distance measuring device 1 according to the first embodiment or the second embodiment of the present disclosure. Then, by mounting the above-mentioned distance measuring device 1 on the smartphone 100 according to the specific example, a good distance image (depth map) can be acquired over a wider section of the distance measuring range, and a good distance image (depth map) can be acquired. Even in an environment where a subject other than the distance measurement target exists at a short distance where scattered light is generated, accurate distance measurement of the distance measurement target subject can be performed.

<Structure that can be taken by this disclosure>
The present disclosure may also have the following configuration.

≪A. Distance measuring device ≫
[A-1] A light source that irradiates a subject with light,
A photodetector that receives reflected light from the subject based on the light emitted from the light source, and
A control unit that controls exposure according to the distance between the distance measuring device and the subject is provided.
Distance measuring device.
[A-2] The control unit performs exposure control based on the signal value output by the photodetector.
The distance measuring device according to the above [A-1].
[A-3] The control unit controls the light emission / exposure conditions of the next frame based on the imaging data of the current frame output by the photodetector and the light emission / exposure conditions.
The distance measuring device according to the above [A-2].
[A-4] The control unit performs exposure control so as to maintain the specified first confidence value in the control of the relatively distant view.
The distance measuring device according to the above [A-3].
[A-5] The control unit performs exposure control so as to maintain the specified exposure time in the control of the relatively near view.
The distance measuring device according to the above [A-3].
[A-6] The control unit separates the ambient light component incident on the photodetector and the reflected light component from the subject, and controls the reflected light component.
The distance measuring device according to the above [A-4] or the above [A-5].
[A-7] The control unit estimates the ambient light component based on the image data output by the photodetector, and separates the reflected light component and the ambient light component.
The distance measuring device according to the above [A-6].
[A-8] The control unit adaptively controls the amount of noise of the reflected light component with reference to the signal value output by the photodetector.
The distance measuring device according to the above [A-2].
[A-9] The light detection unit includes a distance measuring unit that performs a process of acquiring distance image information using image data of the current frame including the distance information detected for each pixel.
The distance measuring device according to any one of the above [A-1] to the above [A-8].
The [A-10] control unit performs exposure control so as to maintain the specified second confidence value in the control of the relatively close view.
The distance measuring device according to the above [A-3].
[A-11] In the ultra-near view, the distance to the subject is such a short distance that the influence of scattered light is generated by the presence of the subject not subject to distance measurement.
The distance measuring device according to the above [A-10].

≪B. Electronic equipment ≫
[B-1] A light source that irradiates a subject with light,
A photodetector that receives reflected light from the subject based on the light emitted from the light source, and
A control unit that controls exposure according to the distance between the distance measuring device and the subject is provided.
An electronic device that has a distance measuring device.
[B-2] The control unit performs exposure control based on the signal value output by the light detection unit.
The electronic device according to the above [B-1].
[B-3] The control unit controls the light emission / exposure conditions of the next frame based on the imaging data of the current frame output by the photodetector and the light emission / exposure conditions.
The electronic device according to the above [B-2].
[B-4] The control unit performs exposure control so as to maintain the specified first confidence value in the control of the relatively distant view.
The electronic device according to the above [B-3].
[B-5] The control unit performs exposure control so as to maintain a specified exposure time in the control of a relatively near view.
The electronic device according to the above [B-3].
[B-6] The control unit separates the ambient light component incident on the photodetector and the reflected light component from the subject, and controls the reflected light component.
The electronic device according to the above [B-4] or the above [B-5].
[B-7] The control unit estimates the ambient light component based on the image data output by the photodetector, and separates the reflected light component and the ambient light component.
The electronic device according to the above [B-6].
[B-8] The control unit adaptively controls the amount of noise of the reflected light component with reference to the signal value output by the photodetector.
The electronic device according to the above [B-2].
[B-9] The light detection unit includes a distance measuring unit that performs a process of acquiring distance image information using image data of the current frame including the distance information detected for each pixel.
The electronic device according to any one of the above [B-1] to the above [B-8].
The [B-10] control unit performs exposure control so as to maintain the specified second confidence value in the control of the relatively close view.
The electronic device according to the above [B-3].
[B-11] In the ultra-near view, the distance to the subject is such a short distance that the influence of scattered light is generated by the presence of the subject not subject to distance measurement.
The electronic device according to the above [B-10].

1 ... Distance measuring device, 10 ... Subject (measurement object), 20 ... Light source, 30 ... Light detection unit, 40 ... AE control unit, 41 ... Next frame light emission / exposure Condition calculation unit, 42 ... Next frame light emission / exposure control unit, 50 ... Distance measurement unit, 51 ... Distance image calculation unit

Claims (12)

A light source that illuminates the subject,
A photodetector that receives reflected light from the subject based on the light emitted from the light source, and
A control unit that controls exposure according to the distance between the distance measuring device and the subject is provided.
Distance measuring device. The control unit performs exposure control based on the signal value output by the photodetector.
The ranging device according to claim 1. The control unit controls the light emission / exposure conditions of the next frame based on the imaging data of the current frame output by the photodetector and the light emission / exposure conditions.
The ranging device according to claim 2. The control unit performs exposure control so as to maintain the specified first confidence value in the control of the relatively distant view.
The ranging device according to claim 3. The control unit performs exposure control so as to maintain the specified exposure time in the control of the relatively near view.
The ranging device according to claim 3. The control unit separates the ambient light component incident on the photodetector and the reflected light component from the subject, and controls the reflected light component.
The distance measuring device according to claim 4. The control unit estimates the ambient light component based on the image data output by the photodetector, and separates the reflected light component from the ambient light component.
The distance measuring device according to claim 6. The control unit adaptively controls the amount of noise of the reflected light component by referring to the signal value output by the photodetector.
The ranging device according to claim 2. It is provided with a distance measuring unit that performs a process of acquiring distance image information using image data of the current frame including the distance information detected for each pixel of the light detection unit.
The ranging device according to claim 1. The control unit performs exposure control so as to maintain the specified second confidence value in the control of the relatively near view.
The ranging device according to claim 3. The ultra-near view is a short distance so that the distance to the subject is affected by scattered light due to the presence of a subject that is not subject to distance measurement.
The distance measuring device according to claim 10. A light source that illuminates the subject,
A photodetector that receives reflected light from the subject based on the light emitted from the light source, and
A control unit that controls exposure according to the distance between the distance measuring device and the subject is provided.
An electronic device that has a distance measuring device.

Images