Patent Description:
As one of distance measurement methods for measuring the distance to a measurement target by using light, a distance measurement method called direct ToF (Time of Flight) method is available. In distance measurement processing by the direct ToF method, reflected light originating from light emitted from a light source and reflected by a measurement target is received by a light reception element, and the distance to the target is measured on the basis of a time period from emission of light to reception of the light as reflected light. Further, in the direct ToF method, known is a configuration that performs distance measurement using a pixel array in which light reception elements are arrayed in a two-dimensional grid pattern.

In distance measurement using a pixel array, in a case where driving or outputting of a result of distance measurement is performed simultaneously for all of light reception elements included in the pixel array, there are limitations on such points as power consumption, a communication band of data, a circuit scale and so forth. Thus, a division driving method in which a pixel array is divided into plural regions and the divided regions are driven sequentially to perform distance measurement result outputting has been proposed. <CIT> describes systems and methods that use LIDAR technology. In one implementation, a LIDAR system includes at least one processor configured to: control activation of at least one light source for illuminating a field of view; receive from at least one sensor having a plurality of detection elements reflections signals indicative of light reflected from objects in the field of view; dynamically allocate a first subset of the plurality of detection elements to constitute a first pixel; dynamically allocate a second subset of the plurality of detection elements to constitute a second pixel; following processing of the first pixel and the second pixel, dynamically allocate a third subset of the plurality of detection elements to constitute a third pixel, the third subset verlapping with at least one of the first subset and the second subset, and differing from each of the first subset and the second subset; and following processing of the first pixel and the second pixel, dynamically allocate a fourth subset of the plurality of detection elements to constitute a fourth pixel, the fourth subset overlapping with at least one of the first subset, the second subset, and the third subset, and differing from each of the first subset, the second subset, and the third subset. <CIT> describes a system and method for providing a dynamic composite field of view in a scanning lidar system, such as to improve a signal-to-noise ration of detected light. The dynamic composite field of view can include a subset of the available detector pixels, and can thereby reduce noise introduce by noise sources that can scale with a detector area, such as dark current and gain peaking that can be caused by a capacitance of the photodetector. <CIT> describes imaging systems configured to sense, by a light sensor of the imaging system, light received during a time period, process the light received by the light sensor, identify an available measurement period for the imaging system within the time period based on the processed light, and transmit and receive light during a corresponding measurement period in one or more subsequent time periods.

In the division driving method according to the existing technology, for example, the time difference between distance measurement processing for a lower end region of the pixel array and distance measurement processing for an upper end region of the pixel array is great, and there is a possibility that it is difficult to secure the simultaneity of distance measurement results in the entire pixel array. In this case, it is difficult to measure the distance to a measurement target whose distance to the distance measurement apparatus changes at a high speed.

It is an object of the present disclosure to provide a measurement apparatus, a distance measurement apparatus, and a measurement method by which distance measurement with higher accuracy can be achieved.

A measurement apparatus according to the present disclosure includes a light reception section including a light reception element group including plural light reception elements included in a target region, a control section that controls a first light reception element group and a second light reception element group included in the light reception element group, so as to read out the first light reception element group and the second light reception element group during periods different from each other, and a signal processing section that performs signal processing on the basis of a signal read out from at least one of the first light reception element group and the second light reception element group. In the measurement apparatus, a sum set of the first light reception element group and the second light reception element group includes all of the plural light reception elements, and at least part of the first light reception element group is not included in the second light reception element group.

In the following, a first embodiment of the present disclosure is described in detail with reference to the drawings. It is to be noted that, in the following first embodiments, identical elements are denoted by identical reference signs and overlapping description is omitted.

The present disclosure relates to a technology for performing distance measurement using light. Prior to the description of the embodiments of the present disclosure, in order to facilitate understanding, a technology that can be applied to the embodiments is described. In the embodiments, the direct ToF method (Time Of Flight) method is applied as a distance measurement method. The direct ToF method is a method in which reflected light originating from light emitted from a light source and reflected by a measurement target is received by a light reception element and distance measurement is performed on the basis of time of difference between a light emission timing and a light reception timing.

Distance measurement according to the direct ToF method is described briefly with reference to <FIG> is a view schematically depicting distance measurement by the direct ToF method that can be applied to the embodiments. A distance measurement apparatus <NUM> includes a light source section <NUM> and a light reception section <NUM>. The light source section <NUM> is, for example, a laser diode and is driven so as to emit laser light in a pulsed form. The light emitted from the light source section <NUM> is reflected by a measurement target <NUM> and is received as reflected light by the light reception section <NUM>. The light reception section <NUM> includes a light reception element for converting light into an electric signal by photoelectric conversion and outputs a signal corresponding to the received light.

Here, time at which the light source section <NUM> emits light (light emission timing) is represented as time t<NUM> and time at which reflected light originating from the light emitted from the light source section <NUM> and reflected by the measurement target <NUM> is received by the light reception section <NUM> (light reception timing) is represented as time t<NUM>. If it is assumed that a constant c is the light speed (<NUM> × <NUM><NUM>[m/sec]), then the distance D between the distance measurement apparatus <NUM> and the measurement target <NUM> is calculated by the following expression (<NUM>).

The distance measurement apparatus <NUM> repetitively executes the process described above for a plural number of times. The light reception section <NUM> includes plural light reception elements, and the distance D may be calculated on the basis of light reception timings at which reflected light is individually received by the light reception elements. The distance measurement apparatus <NUM> classifies a time period tm from the time t<NUM> of the light emission timing to the light reception timing at which the light is received by the light reception section <NUM> (the time period is referred to as a light reception time period tm) on the basis of a class (bin (bins)), to generate a histogram.

It is to be noted that the light received during the light reception time period tm by the light reception section <NUM> is not limited to the reflected light originating from the light emitted from the light source section <NUM> and reflected by the measurement target. For example, also ambient light around the distance measurement apparatus <NUM> (light reception section <NUM>) is received by the light reception section <NUM>.

<FIG> is a view depicting a histogram of an example based on time at which the light reception section <NUM> receives light, which histogram can be applied to the embodiments. Referring to <FIG>, the axis of abscissa indicates a bin, and the axis of ordinate indicates a frequency for each bin. The bin is a class when a light reception time period tm is classified for each predetermined unit time period d. In particular, the bin #<NUM> corresponds to <NUM> ≤ tm < d; the bin #<NUM> corresponds to d ≤ tm < <NUM> × d; the bin #<NUM> corresponds to <NUM> × d ≤ tm < <NUM> × d;. ; and the bin #(N-<NUM>) corresponds to (N - <NUM>) × d ≤ tm < (N - <NUM>) × d. Where the exposure time period of the light reception section <NUM> is the time period tep, tep = N × d holds.

The distance measurement apparatus <NUM> counts the number of times by which the light reception time period tm is acquired, on the basis of the bins, to determine a frequency <NUM> for each bin and generate a histogram. Here, the light reception section <NUM> also receives light other than reflected light when light emitted from the light source section <NUM> is reflected. As an example of such light that becomes a target and that is other than reflected light, ambient light described hereinabove is available. A portion of the histogram indicated by a range <NUM> includes ambient light components by ambient light. The ambient light is light incident at random to the light reception section <NUM> and becomes noise to the reflected light that is a target.

On the other hand, reflected light that becomes a target is light received according to a specific distance and appears as an active light component <NUM> in the histogram. A bin corresponding to the frequency of a peak in the active light component <NUM> is a bin corresponding to the distance D of the measurement target <NUM>. The distance measurement apparatus <NUM> can calculate the distance D to the measurement target <NUM> according to the expression (<NUM>) given hereinabove, by acquiring representative time of the bin (for example, middle time in the bin) as the time t<NUM> described hereinabove. By using plural light reception results in the manner described above, appropriate distance measurement can be executed against random noise.

<FIG> is a block diagram depicting a configuration of an example of electronic equipment that uses a distance measurement apparatus according to the embodiments. Referring to <FIG>, the electronic equipment <NUM> includes a distance measurement apparatus <NUM>, a light source section <NUM>, a storage section <NUM>, a control section <NUM> and an optical system <NUM>.

The light source section <NUM> corresponds to the light source section <NUM> described hereinabove and is a laser diode that is driven to emit laser light, for example, in a pulsed form. In the light source section <NUM>, a VCSEL (Vertical Cavity Surface Emitting LASER) that emits laser light can be applied as a surface light source. This is not restrictive, and as the light source section <NUM>, a configuration which uses an array in which laser diodes are arrayed on a line such that laser light emitted from the laser diode array is scanned in a direction perpendicular to the line may be applied. Also it is possible to apply another configuration that uses a laser diode as a single light source such that laser light emitted from the laser diode is scanned in horizontal and vertical directions.

The distance measurement apparatus <NUM> includes, corresponding to the light reception section <NUM> described hereinabove, plural light reception elements. The plural light reception elements are arrayed, for example, in a two-dimensional grid pattern to form a light reception face. The optical system <NUM> introduces light incident from the outside to the light reception face included in the distance measurement apparatus <NUM>.

The control section <NUM> controls overall operation of the electronic equipment <NUM>. For example, the control section <NUM> supplies a light emission trigger that is a trigger for causing the light source section <NUM> to emit light, to the distance measurement apparatus <NUM>. The distance measurement apparatus <NUM> causes the light source section <NUM> to emit light at a timing based on the light emission trigger and stores time t<NUM> indicative of the light emission timing. Further, the control section <NUM> performs setting of a pattern for distance measurement to the distance measurement apparatus <NUM> in response to an instruction, for example, from the outside.

The distance measurement apparatus <NUM> counts the number of times, by which time information (light reception time period tm) indicative of a timing at which light is received by the light reception face, within a predetermined time range and obtains a frequency for each bin, to generate a histogram described hereinabove. The distance measurement apparatus <NUM> further calculates a distance D to the measurement target on the basis of the generated histogram. Information indicative of the calculated distance D is stored into the storage section <NUM>.

<FIG> is a block diagram more particularly depicting a configuration of an example of the distance measurement apparatus <NUM> that can be applied to the embodiments. Referring to <FIG>, the distance measurement apparatus <NUM> includes a pixel array section <NUM>, a distance measurement processing section <NUM>, a pixel controlling section <NUM>, an overall controlling section <NUM>, a clock generation section <NUM>, a light emission timing controlling section <NUM>, and an interface (I/F) <NUM>. The pixel array section <NUM>, the distance measurement processing section <NUM>, the pixel controlling section <NUM>, the overall controlling section <NUM>, the clock generation section <NUM>, the light emission timing controlling section <NUM>, and the interface (I/F) <NUM> are arranged, for example, on a single semiconductor chip.

Referring to <FIG>, the overall controlling section <NUM> controls operation of the entire distance measurement apparatus <NUM>, for example, in accordance with a program incorporated therein in advance. Further, the overall controlling section <NUM> can also execute control according to an external controlling signal supplied from the outside. The clock generation section <NUM> generates one or more clock signals to be used in the distance measurement apparatus <NUM>, on the basis of a reference clock signal supplied from the outside. The light emission timing controlling section <NUM> generates a light emission controlling signal indicative of a light emission timing according to a light emission trigger signal supplied from the outside. The light emission controlling signal is supplied to the light source section <NUM> and also to the distance measurement processing section <NUM>.

The pixel array section <NUM> includes plural pixels <NUM>, <NUM>, and so on arrayed in a two-dimensional grid pattern and each including a light reception element. Operation of each pixel <NUM> is controlled by the pixel controlling section <NUM> following an instruction of the overall controlling section <NUM>. For example, the pixel controlling section <NUM> can control reading out of pixel signals from the pixels <NUM> for each block including (p × q) pixels <NUM> including p pixels in the row direction and q pixels in the column direction. Further, the pixel controlling section <NUM> can scan the pixels <NUM> in the row direction and further in the column direction in units of the block, to read out a pixel signal from the pixels <NUM>. This is not restrictive, and the pixel controlling section <NUM> can also control the individual pixels <NUM> independently. Further, the pixel controlling section <NUM> can determine a predetermined region of the pixel array section <NUM> as a target region and determine pixels <NUM> included in the target region as pixels <NUM> of a target for reading out a pixel signal. Further, the pixel controlling section <NUM> can also scan plural rows (plural lines) collectively and further scan them in the column direction, to read out a pixel signal from the pixels <NUM>.

A pixel signal read out from each pixel <NUM> is supplied to the distance measurement processing section <NUM>. The distance measurement processing section <NUM> includes a conversion section <NUM>, a generation section <NUM>, and a signal processing section <NUM>.

A pixel signal read out from each pixel <NUM> and outputted from the pixel array section <NUM> is supplied to the conversion section <NUM>. Here, pixel signals are read out asynchronously from the pixels <NUM> and supplied to the conversion section <NUM>. In particular, a pixel signal is read out from a light reception element and outputted according to a timing at which light is received by each pixel <NUM>.

The conversion section <NUM> converts the pixel signal supplied from the pixel array section <NUM> into digital information. In particular, the pixel signal supplied from the pixel array section <NUM> is outputted corresponding to a timing at which light is received by the light reception element included in the pixel <NUM> to which the pixel signal corresponds. The conversion section <NUM> converts the pixel signal supplied thereto into time information indicative of the timing.

The generation section <NUM> generates a histogram on the basis of the time information into which the pixel signals are converted by the conversion section <NUM>. Here, the generation section <NUM> counts the time information on the basis of a unit time period d set by a setting section <NUM>, to generate a histogram. Details of a histogram generation process by the generation section <NUM> are described later.

The signal processing section <NUM> performs a predetermined calculation process on the basis of data of the histogram generated by the generation section <NUM>, to calculate, for example, distance information. The signal processing section <NUM> generates a curve approximation of the histogram, for example, on the basis of the data of the histogram generated by the generation section <NUM>. The signal processing section <NUM> detects a peak of the curve to which the histogram is approximated and can calculate the distance D on the basis of the detected peak.

When curve approximation of the histogram is to be performed, the signal processing section <NUM> can perform a filter process for the curve to which the histogram is approximated. For example, the signal processing section <NUM> can reduce noise components by performing a low pass filter process for the curve to which the histogram is approximated.

The distance information calculated by the signal processing section <NUM> is supplied to the interface <NUM>. The interface <NUM> outputs the distance information supplied from the signal processing section <NUM> as output data to the outside. As the interface <NUM>, for example, the MIPI (Mobile Industry Processor Interface) can be applied.

It is to be noted that, although the foregoing description describes that distance information obtained by the signal processing section <NUM> is outputted to the outside through the interface <NUM>, this is not restrictive. In other words, a configuration which outputs histogram data, which is data of a histogram generated by the generation section <NUM>, from the interface <NUM> to the outside may be applied. In this case, from distance measurement condition information set by the setting section <NUM>, information indicative of a filter coefficient can be omitted. The histogram data outputted from the interface <NUM> is supplied, for example, to an external information processing apparatus, and is suitably processed.

<FIG> is a schematic view depicting an example of a configuration of a device that can be applied to the distance measurement apparatus <NUM> according to the embodiments. Referring to <FIG>, the distance measurement apparatus <NUM> is configured such that a light reception chip <NUM> and a logic chip <NUM> each including a semiconductor chip are stacked one on another. It is to be noted that, in <FIG>, the light reception chip <NUM> and the logic chip <NUM> are depicted in a separated state for illustration.

In the light reception chip <NUM>, light reception elements <NUM> included in plural pixels <NUM> are arrayed in a two-dimensional grid pattern in a region of the pixel array section <NUM>. In the logic chip <NUM>, a logic array section <NUM> which includes a signal processing section that processes signals acquired by the light reception elements <NUM> is provided. In the logic chip <NUM>, a signal processing circuit section <NUM> that performs processing of signals acquired by the light reception elements <NUM> and an element controlling section <NUM> that controls operation as the distance measurement apparatus <NUM> can be additionally provided adjacent to the logic array section <NUM>.

For example, the signal processing circuit section <NUM> can include the distance measurement processing section <NUM> described hereinabove. Further, the element controlling section <NUM> can include the pixel controlling section <NUM>, the overall controlling section <NUM>, the clock generation section <NUM>, the light emission timing controlling section <NUM>, and the interface <NUM> described hereinabove.

It is to be noted that the configurations on the light reception chip <NUM> and the logic chip <NUM> are not limited to those of this example. Further, the element controlling section <NUM> can be arranged, for example, in the proximity of the light reception elements <NUM> for the purpose of driving and control in addition to the control of the logic array section <NUM>. The element controlling section <NUM> can be provided, in addition to the manner of arrangement depicted in <FIG>, in any region of the light reception chip <NUM> and the logic chip <NUM> such that it has any function.

<FIG> is a view depicting a configuration of an example of the pixel <NUM> that can be applied to the embodiments. Referring to <FIG>, the pixel <NUM> includes a light reception element <NUM>, a resistor <NUM>, an inverter <NUM>, an amplifier <NUM>, and a switch <NUM>.

The light reception element <NUM> converts light incident thereto into an electric signal by photoelectric conversion and outputs the electric signal. In the embodiments, the light reception element <NUM> converts a photon (photon) incident thereto into an electric signal by photoelectric conversion and outputs a pulse according to the incidence of the photon. In the embodiments, as the light reception element <NUM>, a single photon avalanche diode is used. The single photon avalanche diode is hereinafter referred to as a SPAD (Single Photon Avalanche Diode). The SPAD has such a characteristic that, if a high negative voltage that causes avalanche multiplication is kept being applied to the cathode thereof, then an electron generated according to incidence of one photon gives rise to avalanche multiplication and large current flows. By using this characteristic of the SPAD, incidence of one photon can be detected with high sensitivity.

Referring to <FIG>, the light reception element <NUM> that is a SPAD is connected at the cathode thereof to a terminal of a power supply potential VDD through the resistor <NUM> and at the anode thereof to a terminal of a potential GND(<NUM>) that is lower in potential than the power supply potential VDD. The terminal of the potential GND(<NUM>) is, for example, a ground terminal or a terminal of a predetermined negative voltage. Consequently, a reverse bias is applied to the light reception element <NUM>. Further, photocurrent flows in a direction from the cathode toward the anode of the light reception element <NUM>.

It is to be noted that the light reception element <NUM> is not limited to the SPAD. It is also possible to apply, as the light reception element <NUM>, an avalanche photodiode (APD) and an ordinary photodiode.

The resistor <NUM> is connected at one end thereof to the power supply potential VDD and at the other end thereof to the cathode of the light reception element <NUM>. Every time incidence of a photon is detected by the light reception element <NUM>, photocurrent flows to the resistor <NUM>, and the cathode potential of the light reception element <NUM> drops to a value in an initial state that is lower than the power supply potential VDD (quenching operation).

A signal extracted from the junction of the resistor <NUM> and the cathode of the light reception element <NUM> is inputted to the inverter <NUM>. The inverter <NUM> inverts the signal of the cathode potential of the light reception element <NUM> inputted thereto and supplies a resulting inverted output signal Vsig to the amplifier <NUM> through the switch <NUM> that is controlled between on and off by a control signal SH_ON. The amplifier <NUM> shapes and outputs the inverted output signal Vsig into and as a pulse Vpls. Meanwhile, the potential GND(<NUM>) on the ground side to which the inverter <NUM> and the amplifier <NUM> are connected is different from the potential GND(<NUM>) on the ground side to which the anode of the light reception element <NUM> is connected.

It is to be noted that, although, in <FIG>, outputting of the inverted output signal Vsig is controlled between on and off with the control signal SH_ON, this example is not restrictive. In particular, the control signal SH_ON may control a different function if it can stop outputting of the pulse Vpls from the pixel <NUM>. For example, supply of the power of the power supply potential VDD to be supplied to the pixel <NUM> may be controlled between on and off with the control signal SH_ON.

Further, in <FIG>, the light reception element <NUM> and the resistor <NUM> are formed on the light reception chip <NUM>. Meanwhile, the inverter <NUM>, the amplifier <NUM>, and the switch <NUM> are formed on the logic chip <NUM>. The junction of the resistor <NUM> and the cathode of the light reception element <NUM> and the input end of the inverter <NUM> are connected to each other between the light reception chip <NUM> and the logic chip <NUM>, for example, through a coupling portion <NUM> by CCC (Copper-Copper Connection) or the like.

Now, prior to the description of the present disclosure, a scanning method of the pixel array section <NUM> according to an existing technology is roughly described. <FIG> are views depicting examples of a scanning method of the pixel array section <NUM> according to an existing technology.

For example, referring to <FIG>, the pixel array section <NUM> has a size of X pixels (for example, <NUM> pixels) × Y lines (for example, <NUM> lines) and is configured such that a total of (X × Y) pixels <NUM> are arrayed in a two-dimensional grid pattern in X pixels and Y lines in the horizontal direction and the vertical direction in <FIG>. Further, in the example of <FIG>, distance measurement of the pixels <NUM> in the pixel array section <NUM> is performed for each block <NUM> of p pixels × q pixels (for example, <NUM> pixels × <NUM> pixels). More particularly, for each block <NUM>, a distance measurement process including exposure, photon detection, histogram generation, and peak detection is performed for each of the pixels <NUM> included in the block <NUM>. In other words, the block <NUM> is an addition unit with which the number of light reception time periods tm is added upon histogram generation.

As depicted in <FIG>, in a case where a distance measurement process is executed at the same time for the blocks <NUM> in the overall area of the pixel array section <NUM>, there are constraints in terms of power consumption, a communication band for data, a circuit scale and so forth. Thus, it has been proposed to divide the pixel array section <NUM> into plural regions and perform a distance measurement process sequentially for the divided regions.

<FIG> is a view schematically depicting execution of a distance measurement process where the pixel array section <NUM> is divided into plural regions. As depicted in <FIG>, the pixel array section <NUM> is divided into regions according to the height of the block <NUM> in the vertical direction, and a distance measurement process is executed for each of the divided regions. Each of regions into which the pixel array section <NUM> is divided in the vertical direction according to the height of the block <NUM> is hereinafter referred to as a row of the blocks <NUM>, or simply as a "row. " In the description given below, unless otherwise specified, the term "row" signifies this row of the blocks <NUM>.

Referring to <FIG>, if a distance measurement process for a row at the lower end of the pixel array section <NUM> ends (first time), then a distance measurement process is executed for the blocks <NUM> in a row immediately above the first-mentioned row (second time). Thereafter, the pixel array section <NUM> is scanned in the horizontal direction in a unit of the blocks <NUM> to perform a distance measurement process similarly, and this scanning in a unit of a row is sequentially executed for rows adjacent to each other in the vertical direction. The method of sequentially executing scanning in a unit of a row in the vertical direction for the overall pixel array section <NUM> is called rolling scanning. By executing the rolling scanning, the power consumption per unit time and the communication band for data can be reduced, and the circuit scale can be reduced.

However, according to the existing technology, time is required after a distance measurement process is executed for a row at the lower end of the pixel array section <NUM> until a distance measurement process is executed for a row at the upper end of the pixel array section <NUM>, and there is a possibility that the simultaneity in distance measurement over the overall pixel array section <NUM> is impaired. For example, in such a case that a mobile body is a measurement target or an apparatus for performing distance measurement is itself mounted on a mobile body, it is difficult to acquire distance measurement information of high accuracy.

Now, a first embodiment of the present disclosure is described. In the first embodiment of the present disclosure, an interlace scanning method is applied to pixels <NUM> included in a pixel array section <NUM>. <FIG> is a view for illustrating a scanning method in a distance measurement apparatus <NUM> according to the first embodiment. It is to be noted that <FIG> corresponds to <FIG> described hereinabove and that the pixel array section <NUM> has a size of X pixels × Y pixels and is configured such that a total of (X × Y) pixels <NUM> are arrayed in a two-dimensional grid pattern so that X and Y pixels <NUM> are included respectively in a horizontal direction and a vertical direction in <FIG>. Further, in the example of <FIG>, the pixels <NUM> in the pixel array section <NUM> perform distance measurement for each block <NUM> of p pixels × q pixels (for example, <NUM> pixels × <NUM> pixels). The block <NUM> is an addition unit with which the number of light reception time periods tm is added upon generation of a histogram.

Further, in the following description, unless otherwise specified, it is assumed that all pixels <NUM> included in the pixel array section <NUM> configure a target region that is a target for reading out a pixel signal.

Referring first to the left side in <FIG>, the distance measurement apparatus <NUM> according to the first embodiment determines one row (first row), for example, at the lower end of the pixel array section <NUM>, as a scanning range, and performs scanning of the scanning range to perform a distance measurement process for each block <NUM>. Then, the distance measurement apparatus <NUM> determines, skipping the second row of the pixel array section <NUM>, the third row as a scanning range and performs scanning of the scanning range to perform a distance measurement process for each block <NUM> in the scanning range. The distance measurement apparatus <NUM> thereafter performs scanning of the odd-numbered rows by similarly skipping the even-numbered rows. In particular, where m = <NUM>, <NUM>, <NUM>,. holds, the distance measurement apparatus <NUM> sequentially executes scanning of the (<NUM>-<NUM>)th rows. The period from start to finish of scanning of the odd-numbered rows is defined as a first frame (Frame) period.

After the distance measurement process for the odd-numbered rows during the first frame period ends, scanning of the even-numbered rows of the pixel array section <NUM> is executed. In particular, referring to the right side in <FIG>, the distance measurement apparatus <NUM> determines, for example, the second row from the lower end of the pixel array section <NUM>, as a scanning range, and scans the scanning range to perform distance measurement for each block <NUM> in the scanning range. Then, the distance measurement apparatus <NUM> determines, skipping the third row of the pixel array section <NUM>, the fourth row as a scanning range and performs scanning of the scanning range to perform a distance measurement process for each block <NUM> in the scanning range. Thereafter, the distance measurement apparatus <NUM> performs scanning of the even-numbered rows by similarly skipping the odd-numbered rows. In particular, where m = <NUM>, <NUM>, <NUM>,. holds, the distance measurement apparatus <NUM> sequentially executes scanning of the (<NUM>)th rows. This period from start to end of scanning of the even-numbered rows is defined as a second frame period.

In the first embodiment, rows for which scanning is performed do not overlap between the first frame period and the second frame period, as described above. In other words, it can be considered that a first light reception element group that is a set of pixels <NUM> that are read out during the first frame period does not include any pixel <NUM> included in a second light reception element group that is a set of pixels <NUM> that are read out during the second frame period and that the sum set of the first light reception element group and the second light reception element group includes a light reception element group including all pixels <NUM> included in a target region that becomes a distance measurement target in the pixel array section <NUM>.

<FIG> is a view depicting a configuration of a first example of the pixel array section <NUM> according to the first embodiment, focusing on wiring lines for the pixels <NUM>. It is to be noted that, in <FIG>, the height of one row is two pixels (two lines) and the blocks <NUM> have a size of <NUM> pixels × <NUM> pixels (two lines) for the convenience of description.

Referring to <FIG>, it is assumed that the value "a" is an odd-number value equal to or greater than three and the (a-<NUM>)th row, the (a-<NUM>)th row, and the ath row are defined from the bottom. In this case, for example, the ath row and the (a-<NUM>)th row are odd-numbered rows and the (a-<NUM>)th row is an even-numbered row. Focusing on the ath row among them, description is given taking, as an example, the pixels <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, and <NUM><NUM> and the pixels <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, and <NUM><NUM> individually included in a block <NUM>.

Pulses Vpls<NUM>, Vpls<NUM>, Vpls<NUM>, Vpls<NUM>, Vpls<NUM>, and Vpls<NUM> outputted from the pixels <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, and <NUM><NUM> of a line on the upper stage of the block <NUM> in the ath row are supplied to the conversion section <NUM> in the distance measurement processing section <NUM> (not depicted) through signal lines <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, <NUM><NUM>, and <NUM><NUM>, respectively.

Also the pixels <NUM><NUM> to <NUM><NUM> of a line on the lower stage of the block <NUM> in the ath row are similar to the pixels <NUM><NUM> to <NUM><NUM> described above. In particular, pulses Vpls<NUM> to Vpls<NUM> outputted from the pixels <NUM><NUM> to <NUM><NUM> are inputted to the conversion section <NUM> through signal lines <NUM><NUM> to <NUM><NUM>, respectively.

The conversion section <NUM> outputs digital values individually corresponding to time periods during which the pulses Vpls<NUM> to Vpls<NUM> and the pulses Vpls<NUM> to Vpls<NUM> are supplied from the signal lines <NUM><NUM> to <NUM><NUM> and the signal lines <NUM><NUM> to <NUM><NUM>, respectively.

┘ On the other hand, for each row, control lines <NUM><NUM> and <NUM><NUM> are provided in a vertical direction (column direction). The control lines <NUM><NUM> are connected, for example, to the pixels <NUM><NUM> to <NUM><NUM> and the pixels <NUM><NUM> to <NUM><NUM> in the blocks <NUM> of the odd-numbered rows (in the example of <FIG>, the ath row and the (a-<NUM>)th row). Meanwhile, the control lines <NUM><NUM> are connected, for example, to the pixels <NUM><NUM> to <NUM><NUM> and the pixels <NUM><NUM> to <NUM><NUM> in the blocks <NUM> of the even-numbered rows (in the example of <FIG>, the (a-<NUM>)th row).

Along the control lines <NUM><NUM> and <NUM><NUM>, control signals for controlling measurement operation of the pixels <NUM><NUM> to <NUM><NUM> and the pixels <NUM><NUM> to <NUM><NUM> connected respectively thereto are transmitted. For example, for the control signals, a control signal SH_ON for controlling on/off of the switch <NUM> (refer to <FIG>) can be used. In the example of <FIG>, a control signal SH_ON<NUM> is supplied to the pixels <NUM><NUM> to <NUM><NUM> and the pixels <NUM><NUM> to <NUM><NUM> in the blocks <NUM> of the odd-numbered rows through the control line <NUM><NUM>. Meanwhile, a control signal SH_ON<NUM> is supplied to the pixels <NUM><NUM> to <NUM><NUM> and the pixels <NUM><NUM> to <NUM><NUM> in the blocks <NUM> of the even-numbered rows through the control line <NUM><NUM>.

The control signals SH_ON<NUM> and SH_ON<NUM> are generated by the pixel controlling section <NUM>, for example, in response to an instruction of the overall controlling section <NUM> and are supplied to the pixel array section <NUM> (refer to <FIG>). The pixel controlling section <NUM> outputs the control signal SH_ON<NUM>, which controls the switch <NUM> to turn on during the first period and to turn off during the second period, to the control line <NUM><NUM>. Further, the pixel controlling section <NUM> outputs the control signal SH_ON<NUM>, which controls the switch <NUM> to turn off during the first period and to turn on during the second period, to the control line <NUM><NUM>. Consequently, what becomes possible is interlace scanning in which the first period and the second period are respectively determined as the first frame period and the second frame period described hereinabove with reference to <FIG>.

<FIG> is a view depicting an example of a configuration of a pixel array section <NUM>' according to a second example of the first embodiment, focusing on wiring lines for the pixels <NUM>. It is to be noted that, in <FIG>, the height of one row is two pixels and the blocks <NUM> have a size of <NUM> pixels × <NUM> pixels (two lines) for the convenience of description similarly as in <FIG> described hereinabove. In the configuration of <FIG> described hereinabove, in the pixel array section <NUM>, the signal lines <NUM><NUM>, <NUM><NUM>, and so on are provided for the pixels <NUM> aligned in the horizontal direction. Thus, the number of wiring lines becomes very great, and a great wiring line area is required.

In contrast, in the configuration depicted in <FIG>, the signal lines <NUM><NUM> to <NUM><NUM> and the signal lines <NUM><NUM> to <NUM><NUM> are shared for each predetermined number of pixels <NUM> on a line.

In particular, in blocks <NUM>, <NUM>, and so on adjacent to each other in the same row, pulses Vpls<NUM>, Vpls<NUM>', and so on outputted from the pixel <NUM><NUM>, pixel <NUM><NUM>', and so on, respectively, are supplied to the conversion section <NUM>, with the signal line <NUM><NUM> shared. In the blocks <NUM>, <NUM>, and so on, pulses Vpls<NUM>, Vpls<NUM>', and so on outputted from the pixel <NUM><NUM>, pixel <NUM><NUM>', and so on, respectively, are supplied to the conversion section <NUM>, with the signal line <NUM><NUM> shared. Further, pulses Vpls<NUM>, Vpls<NUM>', and so on outputted from the pixel <NUM><NUM>, pixel <NUM><NUM>', and so on, respectively, are supplied to the conversion section <NUM>, with the signal line <NUM><NUM> shared. Also the signal lines <NUM><NUM> to <NUM><NUM> are similarly shared by individually corresponding pixels <NUM> in the blocks <NUM>, <NUM>, and so on adjacent to each other in the same row.

Similarly, in the blocks <NUM>, <NUM>, and so on, pulses Vpls<NUM>, Vpls<NUM>', and so on outputted from the pixel <NUM><NUM>, pixel <NUM><NUM>', and so on, respectively, are supplied to the conversion section <NUM> , with the signal line <NUM><NUM> shared. Further, in the blocks <NUM>, <NUM>, and so on, pulses Vpls<NUM>, Vpls<NUM>', and so on outputted from the pixel <NUM><NUM>, pixel <NUM><NUM>', and so on, respectively, are supplied to the conversion section <NUM>, with the signal line <NUM><NUM> shared. Further, in the blocks <NUM>, <NUM>, and so on, pulses Vpls<NUM>, Vpls<NUM>', and so on outputted from the pixel <NUM><NUM>, pixel <NUM><NUM>', and so on, respectively, are supplied to the conversion section <NUM>, with the signal line <NUM><NUM> shared. Also the signal lines <NUM><NUM> to <NUM><NUM> are similarly shared by individually corresponding pixels <NUM> in the blocks <NUM>, <NUM>, and so on adjacent to each other in the same row.

Where a signal line for transmitting a pulse Vpls is shared by plural pixels <NUM> in the manner described above, it is possible to reduce the number of wiring lines for the signal lines and reduce the wiring line area.

In this second example, where pulses Vpls are outputted simultaneously from plural pixels <NUM> that share a signal line for transmitting a pulse Vpls, it cannot be determined from which one of the plural pixels <NUM> the pulse Vpls is outputted. As an example, referring to <FIG>, where a pulse Vpls is supplied from a signal line <NUM>c to the conversion section <NUM> in the (a-<NUM>)th row, it is very difficult to specify from which one of pixels <NUM>A and <NUM>B (each indicated with an oblique line) that share the signal line <NUM>C this pulse Vpls is outputted.

This can be solved, for example, by scanning light emitted from the light source section <NUM> in the horizontal direction. <FIG> is a view illustrating scanning of light of the light source section <NUM> in the horizontal direction, which can be applied to the first embodiment.

On the left side in <FIG>, an example of a configuration for performing such scanning as just described is depicted. A light source <NUM> that is, for example, a laser diode, is excited to generate light at a predetermined light emission timing and emits laser light. The laser light emitted from the light source <NUM> is condensed by a condensing lens <NUM> and is reflected by a polarizing beam splitter <NUM> such that it is applied to a micromirror <NUM>. To the micromirror <NUM>, for example, MEMS (Micro Electro Mechanical Systems) can be applied, and by the micromirror <NUM>, the direction of reflected light arising from applied light and reflected can be changed within a predetermined angular range under the control from the outside.

Part of the laser light emitted as reflected light from the micromirror <NUM> is reflected by a measurement target <NUM>, and the reflected light is applied to the micromirror <NUM>. The reflected light from the measurement target <NUM> applied to the micromirror <NUM> is reflected by the micromirror <NUM> and is applied to the pixel array section <NUM>' through a light receiving lens <NUM>.

Here, the laser light applied from the light source <NUM> and reflected by the micromirror <NUM> is shaped using, for example, an aperture in which a slit is provided in the vertical direction, such that it has a shape narrow in the horizontal direction and elongated in the vertical direction and is then applied toward the measurement target <NUM>. Further, the micromirror <NUM> is driven to scan the light in the horizontal direction. Consequently, the reflected light originating from laser light emitted from the light source <NUM> and reflected by the measurement target <NUM> is received solely at a region <NUM> having a predetermined width in the horizontal direction and being elongated in the vertical direction, by the pixel array section <NUM>'.

In an example of the right side in <FIG>, the pixel <NUM>B is included in the region <NUM> and the pixel <NUM>A is outside the region <NUM>. Accordingly, by synchronizing driving for scanning of the micromirror <NUM> in the horizontal direction and processing by the distance measurement processing section <NUM> for the pulse Vpls with each other, it can be specified that the pulse Vpls supplied to the distance measurement processing section <NUM> through the signal line <NUM>C is a signal outputted from the pixel <NUM>B.

<FIG> is a view more particularly illustrating scanning of rows in the pixel array section <NUM> according to the first embodiment. It is to be noted that, in <FIG>, the height of one row is two pixels (two lines) for the convenience of description. Further, here, the configuration of the pixel array section <NUM> described with reference to <FIG> is applied.

In the distance measurement apparatus <NUM>, for example, the overall controlling section <NUM> sets a target region <NUM> that is a region of a target for performing detection of light, with respect to the pixel array section <NUM>. In the example of <FIG>, the width of the target region <NUM> corresponds to the width of the pixel array section <NUM> in the horizontal direction, and where the value n is a predetermined natural number, the target region <NUM> has a height corresponding to 2n lines (2n pixels). Further, the lower end of the target region <NUM> is set to a position higher by two pixels than the lower end of the pixel array section <NUM>, and the upper end of the target region <NUM> is set to a position lower by two pixels than the upper end of the pixel array section <NUM>.

In the distance measurement apparatus <NUM>, the pixel controlling section <NUM> starts scanning of the first row from the lower end of the target region <NUM> during a first frame period depicted on the left side in <FIG>, according to an instruction of the overall controlling section <NUM>. Thereafter, the pixel controlling section <NUM> scans the odd-numbered rows like the third row, fifth row and so forth while skipping each one row.

As a more particular example, the pixel controlling section <NUM> sets the control signal SH_ON<NUM> to a state (on state) for turning on the switch <NUM> (refer to <FIG>) and sets the control signal SH_ON<NUM> to a state (off state) for turning off the switch <NUM>, according to an instruction of the overall controlling section <NUM>. Further, the conversion section <NUM> selects the signal lines <NUM><NUM> to <NUM><NUM> and <NUM><NUM> to <NUM><NUM> of a row that is made a reading out target, according to an instruction of the overall controlling section <NUM>, and performs a process for pulses Vpls<NUM> to Vpls<NUM> and Vpls<NUM> to Vpls<NUM> supplied from the selected signal lines <NUM><NUM> to <NUM><NUM> and <NUM><NUM> to <NUM><NUM>.

The pixel controlling section <NUM> monitors, in scanning of each row, whether or not the scanned row includes the upper end of the target region <NUM> or the row concerns the upper end of the target region <NUM>. In the example of <FIG>, the (2n-<NUM>)th row is scanned during the first frame period, and then when scanning of the (2n+<NUM>)th row skipping one row is executed, the (2n+<NUM>)th row includes the upper end of the target region <NUM>. In this case, the pixel controlling section <NUM> determines that the scanning during the first frame period is completed and advances the processing to scanning for the second frame period.

In a case where the scanning period transits from the first frame period to the second frame period, the pixel controlling section <NUM> adds an offset <NUM> for the height of one row, i.e., for two pixels, to a start position of scanning for the second frame period. Accordingly, during the second frame period, scanning is started from the second row, skipping the first row. Thereafter, the pixel controlling section <NUM> scans the even-numbered rows like the fourth row, sixth row and so forth while successively skipping one row.

The pixel controlling section <NUM> monitors, in scanning of each row, whether or not the scanned row includes the upper end of the target region <NUM> or the row concerns the upper end of the target region <NUM> similarly as during the first frame period. In the example of <FIG>, when scanning of the 2nth row is executed, the pixel controlling section <NUM> determines that the 2nth row concerns the upper end of the target region <NUM> and determines that the scanning during the second frame period is completed. After the pixel controlling section <NUM> determines that the scanning during the second frame period is completed, it advances the processing to scanning during the first frame period. Upon transition from the second frame period to the first frame period, the pixel controlling section <NUM> does not perform addition of an offset to the scanning start position.

The distance measurement apparatus <NUM> repeats scanning of odd-numbered rows during the first frame period and scanning of even-number rows during the second frame period in such a manner as described above, to perform distance measurement. The scanning during each of the first frame period and the second frame period can be executed in a period of time of one half of that in an alternative case in which all of the pixels <NUM> included in the pixel array section <NUM> are scanned successively.

Now, a data process according to the first embodiment is described with reference to <FIG> described hereinabove. In the pixel array section <NUM>, by applying the interlace scanning in which scanning of odd-numbered rows is performed during the first frame period and scanning of even-numbered rows is performed during the second frame period, for example, three different data processes described below can be implemented.

Note that, it is assumed that, in the following description, the target region <NUM> described hereinabove includes all pixels <NUM> included in the pixel array section <NUM>.

As a first process, a process using one of a distance measurement result during the first frame period and a distance measurement result during the second frame period is possible. For example, by using a distance measurement result during the first frame period during which scanning is performed first, distance measurement at a high speed (for example, in half a period of time) becomes possible in comparison with that in an alternative case in which a distance measurement result based on output of all pixels <NUM> included in the pixel array section <NUM> is used.

In this case, since the number of pixels <NUM> used in distance measurement becomes one half in comparison with that in an alternative case in which a distance measurement result based on output of all pixels <NUM> included in the pixel array section <NUM> is used, although the process is disadvantageous in terms of the accuracy, it is possible to recognize an overall state at a high speed. Further, this also makes it possible to easily measure the distance regarding a measurement target that moves at a high speed.

As a second process, a process of calculating the difference between a distance measurement result during the first frame period and a distance measurement result during the second frame period is possible. For example, the difference between distance measurement results of rows adjacent to each other is calculated from distance measurement results of the rows during the first frame period and distance measurement results of the rows during the second frame period. As the difference, for example, a difference between frequencies of corresponding bins in individual histograms can be applied.

In the example of <FIG>, for example, the difference between a distance measurement result of the first row during the first frame period and a distance measurement result of the second row during the second frame period is calculated. Further, the difference between the distance measurement result of the second row during the second frame period and a distance measurement result of the third row during the first frame period is calculated. Further, the difference between the distance measurement result of the third row during the first frame period and a distance measurement result of the fourth row during the second frame period is calculated. Thereafter, the differences between distance measurement results of rows adjacent to each other during the first frame period and the second frame period are sequentially calculated in a similar manner.

Each of the first frame period and the second frame period is a period of time of one half in comparison with that in an alternative case in which all of the pixels <NUM> included in the pixel array section <NUM> are scanned. Thus, according to the second process, distance measurement regarding a measurement target that moves at a higher speed is facilitated.

As a third process, a process of calculating the sum of a distance measurement result during the first frame period and a distance measurement result during the second frame period is possible. In this case, the sum is a process of calculating a sum set of distance information obtained by a distance measurement process during the first frame period and based on output of the pixels <NUM> included in the odd-numbered rows and distance information obtained by a distance measurement process during the second frame period and based on output of the pixels <NUM> included in the even-numbered rows. From the sum set, distance information based on output of all pixels <NUM> included in the pixel array section <NUM> can be obtained. Accordingly, distance measurement results of higher accuracy can be obtained in comparison with distance measurement results by the first process described hereinabove.

Furthermore, the first process, the second process, and the third process described above can be executed by common control for scanning of the rows in the pixel array section <NUM>.

<FIG> is a flow chart of an example depicting a reading out process according to the first embodiment. In step S10, the overall controlling section <NUM> sets a region for reading out during a first frame period and a region for reading out during a second frame period, with respect to the pixel controlling section <NUM>. The overall controlling section <NUM> may set the regions according to an instruction from the outside or may set the regions according to information stored in advance, for example, in a register or the like provided in the overall controlling section <NUM>.

The overall controlling section <NUM> executes reading out during the first frame period in the next step S11. In particular, the overall controlling section <NUM> instructs the pixel controlling section <NUM> to execute reading out during the first frame period according to the information set in step S10. The pixel controlling section <NUM> executes reading out during the first frame period according to the instruction. After the reading out during the first frame period ends, in the next step S12, the overall controlling section <NUM> executes reading out during the first frame period according to the information set in step S10. In particular, the overall controlling section <NUM> instructs the pixel controlling section <NUM> to execute reading out during the second frame period. The pixel controlling section <NUM> executes reading out during the second frame period according to the instruction. After the reading out during the second frame period ends, the processing transits to the next step S13.

In step S13, the signal processing section <NUM> executes, for example, signal processing based on results of reading out in steps S11 and S12, under the control of the overall controlling section <NUM>. In particular, the signal processing section <NUM> executes signal processing using at least one of a distance measurement result obtained on the basis of the pixel signals read out during the first frame period in step S11 and a distance measurement result obtained on the basis of the pixel signals read out during the second frame periods in step S12. At this time, the signal processing section <NUM> can execute signal processing of one or more of the first process, the second process, and the third process described hereinabove. It is to be noted that it is also possible for the overall controlling section <NUM> to cause the process in step S13 and the processes in steps S11 and S12 to be executed in parallel.

After the signal processing in step S13 is completed, if an instruction to end the processing is received, for example, from the outside (step S14, "Yes"), then the overall controlling section <NUM> ends the series of processes of the flow chart of <FIG>. If an instruction to end the processing is not received (step S14, "No"), then the overall controlling section <NUM> returns the processing to step S11 to execute the processes in steps S11 to S13.

Now, a first modification of the first embodiment is described. The first modification of the first embodiment is an example in which the irradiation range of laser light to be emitted from the light source section <NUM> and the range of scanning in units of a row in the pixel array section <NUM> are synchronized with each other.

For example, the irradiation range of laser light by the light source section <NUM> in a case in which all of the pixels <NUM> included in the pixel array section <NUM> are determined as a light reception target is determined as the overall irradiation range. Referring to <FIG>, for example, in a case where the first row in the pixel array section <NUM> is scanned during the first frame period, the irradiation range of laser light of the light source section <NUM> is restricted to a range corresponding to the first row on the lower end side of the overall irradiation range. Similarly, in a case where the third row in the pixel array section <NUM> is to be scanned, the irradiation range of the laser light of the light source section <NUM> is restricted to a range corresponding to the third row at a middle portion of the overall irradiation range.

As the configuration of the light source section <NUM> for restricting the irradiation range of the laser light, the configuration that uses the micromirror <NUM> as described hereinabove with reference to <FIG> can be applied. In <FIG>, the configuration is such that laser light shaped to be narrow in the horizontal direction and elongated in the vertical direction is applied. The shape of the laser light applied by the configuration of <FIG> is rotated by <NUM> degrees, for example, by changing the direction of the aperture or the like such that the laser light has such a shape to be narrow in the vertical direction but elongated in the horizontal direction.

By restricting the irradiation range of the laser light of the light source section <NUM> according to scanning in units of a row in the pixel array section <NUM> in the manner described above, the intensity of the laser light to be applied to the measurement target can be increased.

According to the first modification of the first embodiment, an eye-safe (eye-safe) effect against the laser light emitted from the light source section <NUM> can be expected. The eye-safe effect according to the first modification of the first embodiment is described with reference to <FIG>.

<FIG> is a view schematically depicting an example of a case in which the irradiation range of laser light emitted from the light source section <NUM> and the range of scanning in units of a row of the pixel array section <NUM> in rolling scanning are synchronized with each other by an existing technology. In the case of rolling scanning, a first row, a second row, and so on adjacent to each other in the pixel array section <NUM> are sequentially scanned. The irradiation range of laser light by the light source section <NUM> is controlled in synchronism with the scanning of the first row, second row, and so on of the pixel array section <NUM>.

Here, a case in which the face is a measurement target is considered. In <FIG>, a face <NUM> as a measurement target is schematically depicted in a corresponding relation with the pixel array section <NUM>. In this example, depicted is a state in which the lower end of the face <NUM> is detected in scanning of the first row and then the second row, third row, and so on of the face <NUM> are detected such that the overall face <NUM> is detected. On the actual face <NUM>, laser light emitted from the light source section <NUM> is applied within ranges corresponding to the first row, second row, and so on.

In the face <NUM>, application of the laser light to the eyes 501R and <NUM> should be avoided as far as possible. However, in the example of <FIG>, the eyes 501R and <NUM> extend across the third row and the fourth row, and in the scanning of the third row and in the scanning of the fourth row, the laser light from the light source section <NUM> is applied to the eyes 501R and <NUM>.

<FIG> is a view schematically depicting an example of a case in which the irradiation range of laser light emitted from the light source section <NUM> and the range of scanning in units of a row in the pixel array section <NUM> are synchronized with each other in the interlace scanning according to the present technology. In <FIG>, an example of one frame period during which scanning of an odd-numbered row is performed is depicted. In the interlace scanning, during one frame period, after scanning of a certain row ends, next scanning is executed skipping the immediately next row.

In the example of <FIG>, after the scanning of the third row, the fourth row is skipped, and scanning of the fifth row is performed. Accordingly, although the laser light from the light source section <NUM> is applied, at the time of scanning of the third row, to the eyes 501R and <NUM> within a range corresponding to the third row, the range corresponding to the fourth row is not irradiated. Thus, in comparison with the case of rolling scanning, the time for which the laser light is applied to the eyes 501R and <NUM> is reduced, and consequently, the burden on the eyes 501R and <NUM> decreases, and the eye-safe effect can be anticipated.

According to the first modification of the first embodiment, it is further possible to reduce the influence of reflected light that is to enter an adjacent row when the row to be scanned is switched in the pixel array section <NUM>. Reduction of the influence of reflected light that is to enter an adjacent row according to the first modification of the first embodiment is described with reference to <FIG>.

<FIG> is a view schematically depicting an example of a case in which the irradiation range of laser light to be emitted from the light source section <NUM> and the range of scanning in units of a row in the pixel array section <NUM> are synchronized with each other in rolling scanning according to an existing technology. In the case of rolling scanning, the first row, the second row, and so on adjacent to each other in the pixel array section <NUM> are scanned sequentially. In synchronism with the scanning of the first row, second row, and so on in the pixel array section <NUM>, the irradiation range of the laser light by the light source section <NUM> is controlled.

Incidentally, reflected light from a measurement target in scanning of a certain row sometimes has an influence on an adjacent row. The example of <FIG> schematically indicates a state in which reflected light from a measurement target in scanning, for example, of the third row has an influence on the second row that is an adjacent row. Scanning of the second row ends, and the row for which scanning is to be performed is switched from the second row to the third row. Together with the switching of the scanning row, the irradiation range of reflected light from the measurement target moves from a range corresponding to the second row to another range corresponding to the third row. Reflected light is applied to a range rather wide than the range of the third row.

There is a possibility that, of reflected light 442a and reflected light 442b overhanging from the range of the third row, the reflected light 442b that concerns the second row may enter pixels <NUM> on the upper end side of the second row.

For example, it is assumed that the pixels <NUM> on the upper end side of the second row, which are not a scanning target at this point of time, are configured such that not the power of the power supply potential VDD to be supplied to each pixel <NUM> is cut, but, for example, as depicted in <FIG>, output of the light reception element <NUM> included in the pixel <NUM> is masked. In this case, the light reception element <NUM> itself in each of pixels <NUM> on the upper end side of the second row is in an operative state, and if reflected light 442b enters, then the number of reactions increases with respect to the other pixels <NUM> (light reception elements <NUM>) included in the second row, resulting in the possibility of heat generation.

On the contrary, also possible is a case in which, after the scanning switches from scanning of the second row to scanning of the third row, a light component overhanging from the range of the second row of remoter reflected light components originating from the laser light applied upon scanning of the second row enters pixels <NUM> on the lower end side of the third row. In this case, a result of a distance measurement process of the third row is influenced by reflected light at the time of processing of the second row, resulting in a possibility that a correct result is not obtained.

<FIG> is a view schematically depicting an example of a case in which the irradiation range of laser light to be emitted from the light source section <NUM> and the range of scanning in units of a row in the pixel array section <NUM> are synchronized with each other in interlace scanning according to the present disclosure. <FIG> depicts an example during a first frame period during which scanning of odd-number rows is performed.

In the interlace scanning, during one frame period, after scanning of a certain row ends, next scanning is executed skipping the immediately next row. For example, during a first frame period, a distance measurement process is not performed for the immediately preceding and succeeding rows of the third row (for the second row and the fourth row). Accordingly, even if the reflected light 442a and the reflected light 442b overhanging from the range of the third row enter the pixels <NUM> of such rows, an influence of this on a result of distance measurement does not appear.

Now, a second modification of the first embodiment is described. The second modification of the first embodiment is an example in which the height of a row for which scanning is to be performed and the skipping amount by interlace scanning are individually variable.

<FIG> is a view schematically depicting an example in which the height of a row for which scanning is to be performed is variable according to the second modification of the first embodiment. Referring to <FIG>, the height of a row before change is four pixels, and in the example of <FIG>, the height of a uth row is changed from four pixels to six rows. In a case where the width of the block <NUM> does not change from that before the change, by an amount by which the height of a row increases, the number of pixels <NUM> whose number of light reception time periods tm upon generation of a histogram is added increases. By this, the distance measurement result of the uth row after the change of the height of a row can be made more accurate.

<FIG> is a view schematically depicting an example in which the skipping amount by interlace scanning is variable according to the second modification of the first embodiment. Referring to <FIG>, the skipping amount before the change is four pixels, and in the example of <FIG>, the skipping amount upon jumping from a vth row to a (v+<NUM>)th row is changed to six pixels.

In the distance measurement apparatus <NUM> according to the second modification of the first embodiment, the height of a row for which scanning is to be performed and the skipping amount by interlace scanning described above can be set independently of each other. As an example, the control signal SH_ON is supplied individually to pixels <NUM> that are aligned in a column direction, and the pixel controlling section <NUM> controls each control signal SH_ON between on and off states, according to an instruction of the overall controlling section <NUM>. The pixel controlling section <NUM> supplies a control signal SH_ON for an instruction of turning on to pixels <NUM> included in a row for which scanning is to be performed and supplies a control signal SH_ON for an instruction of turning off to pixels <NUM> included in a row to be skipped.

By making it possible to set the height of rows for which scanning is to be performed and the skipping amount by interlace scanning independently of each other in the manner described above, it becomes possible to adjust the speed and the accuracy of a distance measurement process by the distance measurement apparatus <NUM>. Further, it becomes possible to actively execute the adjustment of the speed and the accuracy. For example, it is possible to change adjustment of the speed or the accuracy of the distance measurement process according to a result of distance measurement.

Now, a third modification of the first embodiment is described. In the first embodiment described hereinabove, rows for which scanning is to be performed are not overlapped during the first frame period and the second frame period. In contrast, the third modification of the first embodiment is an example in which ranges for which scanning is to be performed are overlapped during the first frame period and the second frame period.

<FIG> is a view illustrating a scanning method according to the third modification of the first embodiment. In the third modification of the first embodiment, the height of a row for which scanning is to be executed and the skipping amount by interlace scanning are set such that a row for which scanning has been performed and a row for which scanning is to be performed next become adjacent to each other during the same frame period. In the example of <FIG>, the height of a row for which scanning is to be executed is <NUM> pixels and the skipping amount is <NUM> pixels. In this case, during the first frame period, the first row and the third row are adjacent to each other, and during the second frame period, the second row and the fourth row are adjacent to each other.

Further, one row from between two rows for which scanning is executed successively during the first frame period and the second frame period is set such that at least part thereof is not included in the other row. In the example of <FIG>, during the second frame period, scanning is started with an offset by four pixels added to the first frame period.

As described hereinabove, by setting a height and a skipping amount of each row and an offset amount for the second frame period, an overlapping portion <NUM> appears in the second row and the fourth row for which scanning is executed during the second frame period and in the first row and the third row for which scanning is executed during the first frame period.

At this time, in the example of <FIG>, during the first frame period, a lower half of the first row does not overlap with the scanning range during the second frame period, and during the second frame period, an upper half of the fourth row does not overlap with the scanning rage during the first frame period. Further, scanning of the rows during the first frame period and the second frame period is executed such that the sum set of the pixels <NUM> included in the scanning range during the first frame period and the pixels <NUM> included in the scanning range during the second frame period includes all pixels <NUM> included in the pixel array section <NUM>.

In other words, this can be considered that part of the first light reception element group that is a set of the pixels <NUM> that are read out during the first frame period does not include the pixels <NUM> included in the second light reception element group that is a set of the pixels <NUM> read out during the second frame period and that the sum set of the first light reception element group and the second light reception element group includes a light reception element group including all pixels <NUM> included in the target region of the pixel array section <NUM>.

In the overlapping portion <NUM>, the number of pixels <NUM> to which the number of light reception time periods tm is added upon generation of a histogram becomes greater in comparison with that in an alternative case in which scanning ranges do not overlap during the first frame period and the second frame period. Consequently, a distance measurement result of higher accuracy can be obtained. Further, since the addition number of light reception time periods tm increases, it becomes possible to perform noise removal from the generated histogram and improve the accuracy of the time difference between the first frame period and the second frame period.

As an example, control of scanning by the distance measurement apparatus <NUM> according to the third modification of the first embodiment can be performed by control of the control signals SH_ON<NUM> and SH_ON<NUM> described hereinabove with reference to <FIG>. In the case of the third modification of the first embodiment, for example, the control signals SH_ON<NUM> and SH_ON<NUM> are supplied to the respective pixels <NUM> included in the overlapping portion <NUM> and overlapping during the first frame period and the second frame period. In the example of <FIG>, on/off of the switch <NUM> is controlled respectively by the control signals SH_ON<NUM> and SH_ON<NUM>.

For example, in a case where scanning during the first frame period is to be performed, the control signal SH_ON<NUM> is placed in an on state, and the control signal SH_ON<NUM> is placed in an off state. On the other hand, in a case where scanning during the second frame period is to be performed, the control signal SH_ON<NUM> is placed in an off state, and the control signal SH_ON<NUM> is placed in an on state.

Now, a fourth modification of the first embodiment is described. In the first embodiment described hereinabove, scanning of the pixel array section <NUM> is divided into scanning during a first frame period during which scanning for odd-numbered rows is performed and scanning during a second frame period during which scanning for even-numbered rows is performed, to thereby perform interlace scanning. In the first embodiment, upon such interlace scanning, scanning during the second frame period is executed after scanning during the first scanning period is executed. However, this is not restrictive, and scanning during the first frame period may be executed after scanning during the second frame period is executed.

Further, in the first embodiment described hereinabove, a scanning period is divided into two periods including a first frame period during which scanning for odd-numbered rows is performed and a second frame period during which scanning for even-numbered rows is performed, to perform interlace scanning. However, this is not restrictive. For example, where m = <NUM>, <NUM>, <NUM>, and so on holds, a scanning period may be divided into three periods including a frame period during which scanning of the (<NUM>-<NUM>)th rows is executed, another frame period during which scanning of the (<NUM>-<NUM>)th rows is executed, and a further frame period during which scanning of the 3mth rows is executed, to execute interlace scanning. It is also possible to divide the scanning period into four or more periods to execute interlace scanning.

Now, as a second embodiment of the present disclosure, an application example of the first embodiment of the present disclosure and the modifications of the first embodiment is described. <FIG> is a view depicting examples of use in which the distance measurement apparatus <NUM> according to any of the first embodiment and the modifications of the first embodiment described hereinabove is used according to the second embodiment.

The distance measurement apparatus <NUM> described above can be used in various cases in which light such as visible light, infrared light, ultraviolet light, X rays and so forth is to be sensed, for example, as described below.

The technology according to the present disclosure may be applied to an apparatus that is incorporated in a mobile body of any kind such as an automobile, an electric car, a hybrid electric car, a motorcycle, a bicycle, a personal mobility, an airplane, a drone, a ship, or a robot.

<FIG> is a block diagram depicting an example of a schematic configuration of a vehicle control system as an example of a mobile body control system to which the technology according to the present disclosure can be applied.

The vehicle control system <NUM> includes plural electronic control units connected to each other via a communication network <NUM>. In the example depicted in <FIG>, the vehicle control system <NUM> includes a driving system control unit <NUM>, a body system control unit <NUM>, an outside-vehicle information detecting unit <NUM>, an in-vehicle information detecting unit <NUM>, and an integrated control unit <NUM>. In addition, a microcomputer <NUM>, a sound/image output section <NUM>, and a vehicle-mounted network interface (I/F) <NUM> are illustrated as a functional configuration of the integrated control unit <NUM>.

The outside-vehicle information detecting unit <NUM> detects information regarding the outside of the vehicle including the vehicle control system <NUM>. For example, the outside-vehicle information detecting unit <NUM> is connected with an imaging section <NUM>. The outside-vehicle information detecting unit <NUM> makes the imaging section <NUM> image an image of the outside of the vehicle, and receives the imaged image. On the basis of the received image, the outside-vehicle information detecting unit <NUM> may perform processing of detecting an object such as a human, a vehicle, an obstacle, a sign, a character on a road surface, or the like, or processing of detecting a distance thereto. The outside-vehicle information detecting unit <NUM> performs an image process, for example, for a received image and performs an object detecting process or a distance detecting process on the basis of a result of the image process.

The imaging section <NUM> is an optical sensor that receives light and that outputs an electric signal corresponding to a received light amount of the light. The imaging section <NUM> can output the electric signal as an image, or can output the electric signal as information regarding a measured distance. In addition, the light received by the imaging section <NUM> may be visible light, or may be invisible light such as infrared rays or the like.

The in-vehicle information detecting unit <NUM> detects information regarding the inside of the vehicle.

The microcomputer <NUM> can calculate a control target value for the driving force generating device, the steering mechanism, or the braking device on the basis of the information regarding the inside or outside of the vehicle which information is obtained by the outside-vehicle information detecting unit <NUM> or the in-vehicle information detecting unit <NUM>, and output a control command to the driving system control unit <NUM>. For example, the microcomputer <NUM> can perform cooperative control intended to implement functions of an ADAS (advanced driver assistance system) which functions include collision avoidance or shock mitigation for the vehicle, following driving based on a following distance, vehicle speed maintaining driving, a warning of collision of the vehicle, a warning of deviation of the vehicle from a lane, or the like.

In addition, the microcomputer <NUM> can perform cooperative control intended for automatic driving, which makes the vehicle to travel autonomously without depending on the operation of the driver, or the like, by controlling the driving force generating device, the steering mechanism, the braking device, or the like on the basis of the information regarding the surroundings of the vehicle which information is obtained by the outside-vehicle information detecting unit <NUM> or the in-vehicle information detecting unit <NUM>.

In addition, the microcomputer <NUM> can output a control command to the body system control unit <NUM> on the basis of the information regarding the outside of the vehicle which information is obtained by the outside-vehicle information detecting unit <NUM>. For example, the microcomputer <NUM> can perform cooperative control intended to prevent a glare by controlling the headlamp to change from a high beam to a low beam, for example, according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detecting unit <NUM>.

The sound/image output section <NUM> transmits an output signal of at least one of a sound and an image to an output device capable of visually or auditorily notifying an occupant of the vehicle or the outside of the vehicle of information. In the example of <FIG>, an audio speaker <NUM>, a display section <NUM>, and an instrument panel <NUM> are illustrated as the output device. The display section <NUM> may, for example, include at least one of an on-board display and a head-up display.

In <FIG>, the vehicle <NUM> includes, as the imaging section <NUM>, imaging sections <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

The imaging sections <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are, for example, disposed at positions on a front nose, sideview mirrors, a rear bumper, and a back door of the vehicle <NUM> as well as a position on an upper portion of a windshield within the interior of the vehicle. The imaging section <NUM> provided to the front nose and the imaging section <NUM> provided to the upper portion of the windshield within the interior of the vehicle obtain mainly an image of the front of the vehicle <NUM>. The imaging sections <NUM> and <NUM> provided to the sideview mirrors obtain mainly an image of the sides of the vehicle <NUM>. The imaging section <NUM> provided to the rear bumper or the back door obtains mainly an image of the rear of the vehicle <NUM>. An image of the front obtained by the imaging sections <NUM> and <NUM> is used mainly to detect a preceding vehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, or the like.

Incidentally, <FIG> depicts an example of photographing ranges of the imaging sections <NUM> to <NUM>. An imaging range <NUM> represents the imaging range of the imaging section <NUM> provided to the front nose. Imaging ranges <NUM> and <NUM> respectively represent the imaging ranges of the imaging sections <NUM> and <NUM> provided to the sideview mirrors. An imaging range <NUM> represents the imaging range of the imaging section <NUM> provided to the rear bumper or the back door. A bird's-eye image of the vehicle <NUM> as viewed from above is obtained by superimposing image data imaged by the imaging sections <NUM> to <NUM>, for example.

At least one of the imaging sections <NUM> to <NUM> may have a function of obtaining distance information. For example, at least one of the imaging sections <NUM> to <NUM> may be a stereo camera including plural imaging elements, or may be an imaging element having pixels for phase difference detection.

For example, the microcomputer <NUM> can determine a distance to each three-dimensional object within the imaging ranges <NUM> to <NUM> and a temporal change in the distance (relative speed with respect to the vehicle <NUM>) on the basis of the distance information obtained from the imaging sections <NUM> to <NUM>, and thereby extract, as a preceding vehicle, a nearest three-dimensional object in particular that is present on a traveling path of the vehicle <NUM> and that travels in substantially the same direction as the vehicle <NUM> at a predetermined speed (for example, equal to or more than <NUM>/hour). Further, the microcomputer <NUM> can set a following distance to be maintained in front of a preceding vehicle in advance, and perform automatic brake control (including following stop control), automatic acceleration control (including following start control), or the like. It is thus possible to perform cooperative control intended for automatic driving that makes the vehicle travel autonomously without depending on the operation of the driver or the like.

When the microcomputer <NUM> determines that there is a pedestrian in the imaged images of the imaging sections <NUM> to <NUM> and thus recognizes the pedestrian, the sound/image output section <NUM> controls the display section <NUM> so that a square contour line for emphasis is displayed so as to be superimposed on the recognized pedestrian.

Claim 1:
A measurement apparatus (<NUM>) comprising:
a light reception section (<NUM>) including a light reception element group including plural light reception elements (<NUM>) included in a target region;
a control section (<NUM>) that controls a first light reception element group and a second light reception element group included in the light reception element group, so as to read out the first light reception element group and the second light reception element group during periods different from each other; and
a signal processing section (<NUM>) that performs signal processing on a basis of a signal read out from at least one of the first light reception element group and the second light reception element group, wherein
a sum set of the first light reception element group and the second light reception element group includes all of the plural light reception elements (<NUM>), and at least part of the first light reception element group is not included in the second light reception element group,
the plural light reception elements (<NUM>) are arrayed in a two-dimensional grid pattern to form the light reception element group, and
the control section (<NUM>)
sequentially reads out plural first scanning ranges each including plural lines that are included in the first light reception element group and are arranged successively in a column direction of the array of the two-dimensional grid pattern, and,
after the reading out of the plural first scanning ranges,
sequentially reads out plural second scanning ranges each including plural lines that are included in the second light reception element group and are arranged successively in the column direction, characterized in that the control section further
sets a distance between the plural first scanning ranges, the number of lines included in each of the plural first scanning ranges, a distance between the plural second scanning ranges, and the number of lines included in each of the plural second scanning ranges independently of each other.