JP2004361431A - Imaging unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging unit capable of performing accurate range-finding while an increase in calculating time and memory storage capacity required for range-finding. <P>SOLUTION: When a focal distance and a diameter of a diaphragm aperture are small, that is, depth of focus is large, pixel data are read out from pixels arranged every prescribed pieces in all the imaging region of a range-finding sensor part 83 for a range-finding object of a wide range and range-finding is performed based on the pixel data and when the focal distance and the diameter of the diaphragm aperture are large, that is, depth of focus is small, a portion of region of each line sensors 831 to 838 is designated and range-finding of all pixels is performed using pixel data of all the pixels positioned in the region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image pickup apparatus such as a digital camera, a silver halide camera, and a video camera provided with a distance measuring device that measures a subject distance using an image pickup device.
[0002]
[Prior art]
For example, it has a plurality of optical systems and an image sensor provided corresponding to each optical system, receives a light image formed through each optical system by each image sensor, and performs a photoelectric conversion operation ( Imaging devices are widely known, which are equipped with a distance measuring device that calculates a shift amount of an image forming position of each optical image based on an output from an image sensor and measures a distance to a subject from the position shift amount. (For example, Patent Document 1 below).
[0003]
In this type of imaging apparatus, in order to accurately measure the distance to the main subject (distance measurement), it is necessary to reliably detect the main subject in the shooting range.
[0004]
In order to reliably detect the main subject in the photographing range, the image sensor is constituted by a plurality of line sensors, and the plurality of line sensors are arranged in a predetermined direction in a direction perpendicular to the arrangement direction of the pixels of each line sensor. In some cases, the distance measuring device may be configured to capture an image in the photographing range as wide as possible by arranging the line sensors at intervals and increasing the number of pixels to form each line sensor to be long.
[0005]
[Patent Document 1]
JP-A-9-213315
[0006]
[Problems to be solved by the invention]
However, if the line sensor is formed long by increasing the number of pixels, and the distance measurement is performed using the pixel signals obtained from almost all the pixels, the pixel signal increases as the number of pixels increases. In addition, the calculation time required for distance measurement using the pixel signal increases, and for example, the storage capacity of a memory for temporarily storing the pixel signal needs to be increased in order to perform the calculation.
[0007]
Also, if the number of line sensors is reduced and the distance between adjacent line sensors is increased to suppress this increase in pixel signals, the distance to a non-main subject is incorrectly regarded as the distance to the main subject. Therefore, there is a problem that accurate distance measurement becomes difficult.
[0008]
The present invention has been made in view of the above, and an object of the present invention is to provide an imaging device capable of performing accurate distance measurement while preventing an increase in calculation time and memory capacity required for distance measurement. I do.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 includes an imaging device that captures an optical image of a subject, an imaging optical system that has a function of performing focus adjustment, and that forms an optical image of the subject on an imaging surface of the imaging device. An imaging apparatus, comprising: a plurality of distance measuring optical systems; a plurality of distance measuring sensors including a plurality of pixels arranged in at least one direction, provided in correspondence with each of the distance measuring optical systems; In the distance measurement sensor, a first distance measurement unit that specifies a plurality of pixels every predetermined number of pixels and calculates a subject distance based on pixel data obtained from the pixels, and a part of each of the distance measurement sensors And a second distance measuring unit that calculates a subject distance based on pixel data obtained from all the pixels in the imaging region, and the first distance measurement unit according to a set imaging condition. Whether to operate the distance measuring unit or the second distance measuring unit A selection unit for-option, based on the subject distance calculated by the selected distance measurement unit is an imaging apparatus characterized by comprising a driving unit to perform focusing on the imaging optical system.
[0010]
According to the present invention, a light image of a subject is received by each distance measuring sensor via the corresponding distance measuring optical system. Then, the selection unit selects which of the first distance measurement unit and the second distance measurement unit is operated in accordance with the set imaging condition. When the first distance measuring unit is selected by the selecting unit, a plurality of pixels are designated at every predetermined number of pixels in each distance measuring sensor, and a subject distance is calculated based on pixel data obtained from the pixels. Is done. On the other hand, when the second distance measurement unit is selected by the selection unit, a part of the imaging region is specified in each distance measurement sensor, and based on pixel data obtained from all the pixels in the imaging region. The subject distance is calculated. Then, the focus adjustment by the imaging optical system is controlled by the driving unit based on the subject distance calculated by the selected distance measuring unit.
[0011]
According to a second aspect of the present invention, there is provided the image pickup apparatus according to the first aspect, further comprising a unit configured to set an exposure control value for the image sensor based on brightness of a subject, and a focal length of the imaging optical system is changed. The imaging condition is information on a depth of focus that changes according to a focal length or an exposure control value of the imaging optical system, and the selection unit is configured to perform the second imaging in accordance with the magnitude of the depth of focus. One of the first and second distance measuring units is selected.
[0012]
According to this invention, the selector selects one of the first and second distance measuring units according to the depth of focus. Therefore, for example, when the depth of focus is deep, by selecting the first distance measuring unit, it is possible to reliably detect a subject with a wide range as a distance measuring target, and to detect all pixels of each distance measuring sensor. As compared with the configuration in which the distance measurement is performed using the pixel data obtained from the above, the distance measurement operation time can be reduced, and the storage capacity of the storage unit that stores the pixel data for the distance measurement can be reduced.
[0013]
Further, when the depth of focus is shallow, by selecting the second ranging unit, it is possible to secure high ranging accuracy, and to use pixel data obtained from all pixels of each ranging sensor. As compared with the configuration in which distance measurement is performed, the distance measurement calculation time can be reduced, and the storage capacity of the storage unit that stores the pixel data for distance measurement can be reduced.
[0014]
According to a third aspect of the present invention, in the imaging device according to the first or second aspect, the imaging apparatus further includes a finder for visually recognizing an imaging range of the imaging element, and the second distance measurement unit is provided in the finder. The subject distance is calculated using pixel data of an image specified by an index indicating the obtained distance measurement range.
[0015]
According to the present invention, the second distance measuring unit is configured to calculate the subject distance using the pixel data of the image specified by the index indicating the distance measurement range provided in the finder, so that the focal length Accordingly, the subject distance can be appropriately calculated.
[0016]
According to a fourth aspect of the present invention, in the imaging apparatus according to any one of the first to third aspects, after calculating the subject distance by the first distance measuring unit, the calculation result or / and the set imaging condition are set. A determination unit that determines whether to calculate a subject distance by the second distance measurement unit based on the determination of the subject distance by the second distance measurement unit by the determination unit. If it is determined that the calculation is to be performed, a part of the imaging area is designated in each distance measurement sensor based on the subject distance calculated by the first distance measurement unit, and the image is obtained from all the pixels in the imaging area. The object distance is calculated based on the pixel data obtained.
[0017]
According to this invention, after the calculation of the subject distance by the first distance measuring unit, the determining unit calculates the subject distance by the second distance measuring unit based on the calculation result and / or the set imaging condition. It is determined whether or not to perform the calculation. If the determination unit determines that the subject distance is to be calculated by the second ranging unit, the second ranging unit determines the first ranging unit. A part of the imaging area is designated in each distance measurement sensor based on the subject distance calculated by, and the subject distance is calculated based on pixel data obtained from all the pixels in the imaging area.
[0018]
Therefore, when it is necessary to calculate the subject distance with higher accuracy than the first distance measurement unit, for example, when it is determined that the subject distance is large as a result of the calculation of the subject distance by the first distance measurement unit, By calculating the subject distance by the second ranging unit, a more accurate subject distance can be obtained.
[0019]
According to a fifth aspect of the present invention, in the imaging device according to the fourth aspect, the first distance measuring unit executes the calculation of the subject distance a plurality of times, and the determining unit determines the first distance measuring unit. When it is detected that the subject is a moving object based on the calculation result by (1), it is determined that the subject distance is to be calculated by the second distance measuring unit.
[0020]
According to the present invention, the subject distance is calculated a plurality of times by the first distance measuring unit, and when it is detected that the subject is a moving object based on the calculation result, the determining unit performs the second distance measuring. It is determined that the subject distance is calculated by the second distance measuring unit when it is determined that the subject is a moving object as a result of calculating the subject distance by the first distance measuring unit. By calculating the subject distance, a more accurate subject distance can be obtained.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram illustrating an embodiment of an imaging device according to the present invention.
[0022]
As shown in FIG. 1, the imaging apparatus 1 includes an imaging optical system 2, an imaging element 3, a driving unit 4, a finder 5, an input operation unit 6, a photometry unit 7, a distance measurement unit 8, a control unit A part 9.
[0023]
The imaging optical system 2 includes a photographing lens including a zoom lens and a focus lens, and forms an optical image of a subject on the imaging device 3.
[0024]
The image pickup device 3 is a solid-state image pickup device such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and receives an optical image of a subject formed by the imaging optical system 2 and performs photoelectric conversion. It is.
[0025]
The drive unit 4 drives the taking lens of the imaging optical system 2 in the optical axis direction. Although not shown, the drive unit 4 includes an encoding plate in which a plurality of code patterns are formed at a predetermined pitch in the optical axis direction within a moving range of the photographing lens, and is integrated with the photographing lens while sliding on the encoding plate. The encoder brush moves to a position on the encoder plate, and the position of the photographing lens is detected by reading a code pattern on the encoding plate via the encoder brush. The detected position of the taking lens is used for calculating the focal length.
[0026]
The viewfinder 5 is an eyepiece window through which a photographer visually recognizes a photographing range. In the present embodiment, the viewfinder 5 is an optical viewfinder for guiding a light image of a subject to the photographer's eyes via an optical system provided in the viewfinder 5. is there. The finder 5 is provided with an index indicating the distance measurement range, and when the photographer looks into the finder, the target can be visually recognized. When an optical image of a subject is displayed on the viewfinder 5, the target is displayed so as to overlap the optical image.
[0027]
The input operation unit 6 inputs a shutter button for inputting an operation for instructing recording of an image captured by the image sensor 3 and an operation for selecting a mode related to a shooting method such as a still image / movie shooting mode or a moving object shooting mode. Button for inputting an operation for adjusting the imaging magnification, a power switch for inputting an operation for turning on / off a power supply (not shown) of the imaging apparatus 1, and the like. It is.
[0028]
The shutter button is a button that is pressed in two steps (half-press and full-press). When the shutter button 7 is half-pressed, the shutter button 7 is set to an imaging standby state in which shutter speed setting and the like are performed. Thus, for example, a timing to end the exposure to the image sensor 3 is instructed, and an optical image of the subject to be recorded on a predetermined recording medium (for example, a memory card) is determined.
[0029]
The photometric unit 7 includes, for example, a photometric optical system and a photometric sensor that captures an optical image formed by the optical system, and detects the subject brightness by a TTL (through the lenses) photometric method. The detected subject brightness is used when determining an exposure control value (exposure time of the image sensor corresponding to the aperture diameter and the shutter speed).
[0030]
The distance measuring unit 8 has an optical axis different from the optical axis of the imaging optical system 2, and a pair of distance measuring optical systems 81, 82 arranged in parallel, and a general connection of the distance measuring optical systems 81, 82. A distance measuring sensor unit 83 arranged on the image plane is provided, and the distance to the subject (subject distance) is detected by a passive method based on the principle of triangulation which is a well-known technique. Note that the distance measuring unit 8 moves the distance measuring optical system in the optical axis direction in conjunction with the movement of the imaging optical system 2 in the optical axis direction, so that the distance measuring range changes with a change in the imaging magnification. The object distance is detected using pixel data of an image in a range specified by an index provided in the viewfinder.
[0031]
FIG. 2 is a diagram illustrating a configuration of the distance measuring sensor unit 83 according to the present embodiment.
[0032]
As shown in FIG. 2, the distance measuring sensor unit 83 includes a plurality of line sensors 831 to 838 formed of a non-destructive readout solid-state imaging device such as a CMOS, and a drive for data transfer to each of the line sensors 831 to 838. And a control circuit (not shown) for generating a signal.
[0033]
Assuming that a longitudinal direction of the line sensors 831 to 838 is an X-axis direction and a direction perpendicular to the X-axis direction is a Y-axis direction, a line sensor group 837 including line sensors 831 to 834 and a line sensor including line sensors 835 to 838 A group 838 is disposed adjacent to the X-axis direction, and in each of the line sensor groups 837 and 838, the line sensors 831 to 834 and the line sensors 835 to 838 are disposed substantially parallel to the Y-axis direction. Have been.
[0034]
A subject light image is formed on the imaging surface of the line sensor group 837 including the line sensors 831 to 834 by the distance measuring optical system 81, while the imaging surface of the line sensor group 838 including the line sensors 835 to 838 is formed on the imaging surface. The subject light image is formed by the distance measuring optical system 82.
[0035]
The distance measurement sensor unit 83 of the present embodiment can select a pixel to output pixel data by the control unit 9 (an imaging control unit 93 described later in detail), and select the pixel from the pixel that has output the pixel data. Data can be output again.
[0036]
The control unit 9 includes a microcomputer having a built-in storage unit 98 to be described later, which includes, for example, a ROM for storing a control program and a RAM for temporarily storing data, and controls the driving of each unit in the imaging apparatus 1 in association with each other. Things.
[0037]
Further, the control unit 9 functionally includes a photometry information calculation unit 91, a focal length detection unit 92, an imaging control unit 93, a comparison unit 94, a determination unit 95, a distance measurement information calculation unit 96, a drive control unit 97, and a storage unit. 98.
[0038]
The photometry information calculation section 91 calculates the subject brightness based on the photometry information obtained by the photometry section 7. The calculated subject brightness is transmitted to the drive control unit 94 as photometric data and stored in the storage unit 95.
[0039]
The focal length detector 92 detects the focal length based on the code pattern read by the drive unit 4. This focal length is transmitted to the drive control unit 94 and the imaging control unit 95 as focal length data, and is stored in the storage unit 95.
[0040]
The imaging control unit 93 controls the output operation of the drive signal by the control circuit of the distance measurement sensor unit 83 described above. In the present embodiment, the imaging control unit 93 outputs pixel data for distance measurement according to the focal length and the like. The target pixel is changed. Hereinafter, this point will be described.
[0041]
With reference to FIG. 3, the necessary distance measurement range according to the focal length will be described.
[0042]
FIG. 3 shows that when the taking lens is located at a certain position on the wide (wide-angle) side (hereinafter, referred to as a wide position), the taking lens has a viewing angle (imaging range) indicated by an arrow A and is tele (telephoto). When the camera is located at a certain position on the side (hereinafter referred to as a telephoto position), it has a viewing angle indicated by an arrow B.
[0043]
The distance measuring optical systems 81 and 82 of the distance measuring unit 8 have a fixed focal length and always have a viewing angle in a range from a straight line (1) to a straight line (5). A case where an object light image is formed on an image forming surface of the distance measuring sensor unit 83 is shown.
[0044]
In FIG. 3, when the photographing lens is positioned at each of the wide position and the telephoto position to capture an image of a subject located at different distances A and B (distance A> distance B) (for recording using the image sensor 3). (In the case of performing imaging for obtaining an image).
[0045]
As can be seen from FIG. 3, when the photographing lens is located at the wide position and an image of the subject located at the distance A is taken (hereinafter referred to as a pattern (1)), the range from the straight line (1) to the straight line (5) is obtained. Needs to be measured. Also, at this time, since the imaging lens is positioned at the wide position to capture an image of the subject, the focal length is short, the depth of focus is relatively deep (the focusing range on the distance measuring sensor unit 83 side is wide), and the Distance accuracy is not required.
[0046]
On the other hand, when the imaging lens is positioned at the telephoto position and an image of the subject located at the distance A is taken (hereinafter referred to as a pattern (2)), the range from the straight line (2) to the straight line (4) is set as the distance measurement target. do it. Also, at this time, since the imaging lens is positioned at the telephoto position to capture the image of the subject, the focal length is long, and therefore the depth of focus is relatively shallow (the focusing range on the distance measuring sensor unit 83 side is narrow) and high. Ranging accuracy is required.
[0047]
When taking an image of a subject located at a distance B by positioning the taking lens at the wide position (hereinafter referred to as a pattern (3)), the range from the straight line (1) to the straight line (4) needs to be the distance measurement target. There is. Further, at this time, as in the case of the pattern (1), the photographing lens is positioned at the wide position and the subject is imaged, so that the focal length is short, and the focal depth is relatively deep (the focus on the distance measuring sensor unit 83 side is in focus). The range becomes wider), and high ranging accuracy is not required.
[0048]
On the other hand, when the photographing lens is positioned at the telephoto position and an image of a subject located at a distance B is taken (hereinafter referred to as a pattern {circle around (4)}), the range from the straight line {circle around (1)} to the straight line {circle around (3)} is regarded as the distance measurement target. do it. Also, at this time, as in the case of the pattern (2), the imaging lens is positioned at the tele position to image the subject, so that the focal length is long and the depth of focus is relatively shallow (the focusing range on the side of the distance measuring sensor unit 83). Becomes narrower), and high ranging accuracy is required.
[0049]
As described above, in the pattern (1), since the range from the straight line (1) to the straight line (5) needs to be measured, and high ranging accuracy is not required, each line sensor 831 Regarding 838, predetermined pixels (every other pixel in the present embodiment) from which pixel data is to be read are set in the entire pixel arrangement area corresponding to the distance measurement range from the straight line (1) to the straight line (5). The pixel data is read by thinning out the pixels, and the distance is measured based on the pixel data.
[0050]
Similarly, for the pattern (3), since the range from the straight line (1) to the straight line (4) needs to be measured, and high ranging accuracy is not required, each line sensor 831 With regard to 838, pixel data is read out by thinning out pixels from the pixel arrangement area corresponding to the distance measurement range from the straight line (1) to the straight line (4) by setting a predetermined number of pixels from which pixel data is read, Distance measurement is performed based on the pixel data.
[0051]
On the other hand, in the pattern (2), the range from the straight line (2) to the straight line (4) may be set as the object of distance measurement, and a high distance measurement accuracy is required. Pixel data is read from all the pixels in the area corresponding to the distance measurement range up to 4４, and distance measurement is performed based on the pixel data.
[0052]
Similarly, for the pattern (4), the range from the straight line (1) to the straight line (3) may be set as the object of distance measurement, and high distance measurement accuracy is required. Pixel data is read from all the pixels in the area corresponding to the distance measurement range up to the straight line (3), and distance measurement is performed based on the pixel data.
[0053]
As a result, in all of the patterns (1) to (4), shortening of the distance measurement operation time and reduction of the storage capacity of the storage unit are realized, and in the patterns (1) and (3), a wide distance measurement range is obtained. While the distance measurement accuracy is ensured in the patterns (2) and (4).
[0054]
As in the case of the patterns (1) and (3), pixel data is read out by thinning out pixels, and a distance measurement performed based on the read pixel data is called a thinning distance measurement. The pixel data is read from the pixel data, and the distance measurement performed based on the read pixel data is referred to as all pixel distance measurement.
[0055]
In order to realize the above-described configuration, the imaging control unit 93 controls the pixel data output operation of the pixels of the line sensors 831 to 838 as shown in FIG. FIG. 4 illustrates only one line sensor in each of the left and right line sensor groups.
[0056]
As shown in FIG. 4A, the imaging control unit 93 determines that the focal length is larger than a predetermined threshold value and that the aperture diameter of the diaphragm corresponds to, for example, the case where the above-described imaging lens is positioned at the telephoto position for imaging. When at least one of the threshold values is larger than the predetermined threshold value (when the depth of focus is shallow), all the pixels (six pixels in FIG. 4A) located in the central region in each of the line sensors 831 to 838 are used. ) To output pixel data.
[0057]
On the other hand, when the focal length and the aperture opening diameter are smaller than the respective thresholds (when the depth of focus is deep) corresponding to, for example, the case where the above-described photographing lens is positioned at the telephoto position and performs imaging, the imaging control unit 93 performs the following. Process as follows.
[0058]
That is, in this case, once it is determined that it is necessary to image the subject with the entire distance measurement sensor and perform thinning distance measurement and perform high-precision distance measurement, all pixel measurement is performed in a specific area of the line sensor. Make a distance.
[0059]
Based on this, as shown in FIG. 5A, the imaging control unit 93 first sets the light receiving areas of the line sensors 831 to 838 to a plurality of areas (in FIG. 5B, five areas 1 to 5). Then, as shown in FIG. 4B, pixel data is output every other pixel in each of the areas 1 to 5, for example.
[0060]
When the distance value (subject distance) calculated by the distance information calculation unit 96 described later is larger than the threshold value of the distance value (one condition for determining that it is necessary to perform high-precision distance measurement) In each of the line sensors 831 to 838, a pixel in a predetermined area centered on the area where the main subject is imaged is further divided into a plurality of areas (this area is referred to as a small area). Is output.
[0061]
For example, as illustrated in FIG. 5B, the imaging control unit 93 divides the imaging region of each of the line sensors 831 to 838 into, for example, five areas 1 to 5 in the longitudinal direction. For example, pixel data is output every other pixel. Then, a distance measurement value is calculated by the distance measurement information calculation unit 96 based on the pixel data.
[0062]
As a result, the subject of the image captured in the area 3 is closest to the subject, for example, it is determined that this subject is the main subject, and when the distance to the main subject is greater than the subject distance threshold (when the main subject is In a case where it is relatively far from the imaging apparatus 1 and it is considered that accurate distance measurement is necessary again), as shown in FIG. A region consisting of a pixel and a part of the pixels adjacent to the area 3 and belonging to the areas 2 and 4 is divided into, for example, five small areas 1 to 5, and in each of the small areas 1 to 5, Output pixel data. Then, a distance measurement value is calculated based on the pixel data by a distance measurement information calculation unit 96 described later.
[0063]
When the shooting mode of the imaging device 1 is set to the moving object shooting mode, the thinning-out distance measurement described above is performed a plurality of times to detect whether or not a moving object exists.
[0064]
FIG. 6A shows a state in which the main subject moves to the near side within the imaging range of the distance measurement sensor unit 83, and FIG. 5 shows a state in which the main subject moves while maintaining a substantially constant distance from the imaging device 1. FIGS. 6A and 6B each show only one line sensor group.
[0065]
FIG. 7 is a diagram illustrating a method of selecting a pixel for outputting pixel data for one of the line sensors 831 to 838 (for example, the line sensor 832).
[0066]
In FIG. 6A, when each of the line sensors 831 to 834 is divided into five areas (101 to 105, 201 to 205,..., 501 to 505), as a result of performing the thinning-out measurement a plurality of times, For example, the presence of a moving object (main subject) can be detected by detecting that the distance measurement value corresponding to the area 103 or 303 has increased.
[0067]
In FIG. 6B, a moving object (main subject) is detected by detecting that an area in which substantially the same distance measurement value is obtained has moved from, for example, the area 102 to the area 103 as a result of performing the thinned distance measurement a plurality of times. Can be detected.
[0068]
In order to detect whether a moving object is present or not, it is necessary to secure a distance measurement range as wide as possible. Therefore, as shown in FIG. For example, every other pixel (a black pixel in FIG. 7A) is selected from the entire imaging range, and pixel data is output from this pixel.
[0069]
When the presence of the moving object is detected in this manner, as shown in FIG. 7, based on each distance measurement value calculated by the plurality of thinning-out distance measurement, the image pickup area of each line sensor 831 to 838 is displayed. , A partial area including the moving object is designated, and pixel data is output from pixels in this area.
[0070]
That is, as shown in FIG. 7B, for example, assuming that the image of the moving object is mainly captured in the area 203 by the line sensor 832, the imaging control unit 93 specifies the area 203 and specifies the area 203. The pixel and the pixels 202a, 202b, 204a, and 204b of the areas 202 and 204 adjacent to the area 203 are divided into, for example, three small areas 1 to 3, and pixel data is output from all the pixels in each of the small areas 1 to 3. Let it.
[0071]
As a result, the area where the moving object is imaged by the line sensor 832 is specified with higher accuracy, and the subject distance is calculated with higher accuracy.
[0072]
The comparison unit 94 compares whether the focal length, the aperture opening diameter, and the subject distance are each greater than a preset threshold.
[0073]
When the focal length and the aperture opening diameter are smaller than the respective thresholds, the determination unit 95 determines whether or not it is necessary to perform all-pixel distance measurement according to whether the subject distance is larger than the threshold after the thinning-out distance measurement. It is to judge.
[0074]
The ranging information calculation unit 96 calculates a ranging value (subject distance) based on information (ranging information) on the ranging value obtained from the ranging unit 8, and measures information on the ranging value. It is transmitted to the drive control unit 97 as distance data.
[0075]
The drive control unit 97 determines an exposure control value from the photometry data transmitted from the photometry information calculation unit 91, controls the exposure of the image sensor 3 based on the exposure control value, and transmits the exposure control value from the distance measurement information calculation unit 91. The driving amount of the photographing lens is calculated from the measured distance data, and the focusing operation of the photographing lens is performed.
[0076]
The storage unit 98 stores the photometric data calculated by the photometric information calculation unit 91, information on the focal length detected by the focal length detection unit 92, the distance measurement data calculated by the distance measurement information calculation unit 96, and the drive control unit 97. The information about the exposure control value derived by the above is stored.
[0077]
Next, the distance measurement process in the imaging device 1 of the present embodiment will be described with reference to flowcharts shown in FIGS.
[0078]
As shown in FIGS. 8 and 9, first, a shooting mode (for example, a still image / movie shooting mode or a moving object shooting mode) is set (step S1), and an operation for changing the imaging magnification by a zoom switch is input (step S1). When YES in step S2), the drive unit 4 drives the photographing lens along the optical axis in a direction according to the operation (step S3), and the focal length detection unit 92 detects the focal length (step S4). .
[0079]
When the operation of the zoom switch is released and the shutter button is half-pressed (NO in step S2, YES in S5), the photometric unit 7 and the photometric information calculation unit 91 perform photometry to detect the subject brightness, An exposure control value is determined (step S6).
[0080]
Next, when the focal length detected in step S4 is equal to or smaller than the threshold (NO in step S7), and when the aperture diameter determined in step S6 is equal to or smaller than the threshold (NO in step S8), the imaging control unit 93 is set. Determines whether or not the moving object shooting mode is set in step S1 (step S9), and if the moving object shooting mode is set (YES in step S9), as shown in FIG. The thinning-out distance measurement is performed twice or more (step S10), and when the moving object photographing mode is not set (NO in step S9), the thinning-out distance measurement is performed once as shown in FIG. 4A (step S11). ). Here, thinning-out ranging is performed because it is necessary to measure a wide range in order to detect a main subject (including a moving object), and high ranging accuracy is not required.
[0081]
If the distance measurement value obtained by the processing in step S10 or S11 is smaller than the threshold (NO in step S12), as a result of the processing in step S10, the moving object (main subject) is determined by the distance measurement information calculation unit 96. If not detected (NO in step S13), the distance measurement value for performing focus adjustment driving on the photographing lens is determined to be the distance measurement value calculated in step S10 or S11 (step S14).
[0082]
On the other hand, when the focal length exceeds the threshold value (YES in step S7), and when the aperture diameter exceeds the threshold value (YES in step S8), it is possible to narrow the distance measurement range as described above, and high accuracy Since the distance measurement needs to be performed, the imaging control unit 93 performs the distance measurement among the line sensors 831 to 838 as shown in FIG. The target range is limited and set (step S15), and pixel data is read from all the pixels in the area corresponding to the distance measurement range, and the distance measurement information calculation unit 96 performs the distance measurement based on the pixel data. Is performed (steps S16 and S17).
[0083]
Also, when the distance measurement value is larger than the threshold value (YES in step S12) and when a moving object is detected (YES in step S13), the main subject is almost specified, and the approximate subject distance can be calculated. Since the distance measurement needs to be performed with higher accuracy, the imaging control unit 93 sets the range of the line sensors 831 to 838 to be measured as shown in FIGS. 5B and 7C. Is limited (step S15), the pixel data is read from all the pixels in the area corresponding to the distance measurement range, and the distance measurement information calculation unit 96 performs the distance measurement based on the pixel data (step S15). S16, S17).
[0084]
When the distance measurement value is determined in step S14 or S17, the drive control unit 97 adjusts the focus of the photographing lens based on the distance measurement value (step S18), and fully depresses the shutter button (step S19). The image sensor 3 performs an exposure operation (Step S20).
[0085]
As described above, when the focal length and the aperture opening diameter are small, that is, when the depth of focus is deep, the thinning-out distance measurement is performed with the wide range as the object to be measured, so that the main subject can be more reliably detected. A storage unit for shortening distance calculation time and storing pixel data for distance measurement as compared with a configuration in which distance measurement is performed using pixel data obtained from all pixels of the distance measurement sensor unit 83 98 can be reduced.
[0086]
When the focal length or the aperture opening diameter is large, that is, when the depth of focus is shallow, a partial area is designated among the line sensors 831 to 838, and the pixel data of all the pixels located in that area is used. Since all pixel distance measurement is performed, high-precision distance measurement can be performed, and a distance measurement using pixel data obtained from all pixels of the distance measurement sensor unit 83 can be performed. In addition, the distance measurement operation time can be reduced, and the storage capacity of the storage unit 98 that stores the pixel data for distance measurement can be reduced.
[0087]
Even when the depth of focus is deep, even if the subject distance is large (if the main subject is far away from the imaging device 1) or if the main subject is a moving object as a result of the thinning-out ranging, Since pixel distance measurement is performed, highly accurate distance measurement can be performed.
[0088]
When the depth of focus is deep, the subject distance is small, and the main subject is not a moving object, a distance measurement value for driving the taking lens for focus adjustment is obtained by thinning-out distance measurement. Since the value is set as the value, the distance measurement operation time is shortened and the pixel data for distance measurement is stored as compared with a configuration in which distance measurement is performed using pixel data obtained from all pixels of the distance measurement sensor unit 83. The storage capacity of the storage unit 98 can be reduced.
[0089]
In addition, since CMOS is used as a solid-state image pickup device constituting the distance measuring sensor unit 83, the pixel data that has been output can be output again from the pixel that has output the pixel data. In the integration, both the thinned distance measurement and the all pixel distance measurement can be performed.
[0090]
Further, since the distance measuring unit 8 is configured to detect the subject distance using the pixel data of the image in the range specified by the index provided in the finder, it is possible to calculate an appropriate subject distance according to the focal length. It can be carried out.
[0091]
The present invention is not limited to the above embodiment, and the following modifications (1) to (3) can be adopted.
(1) The form of the image sensor is not limited to the one configured by the plurality of line sensors 831 to 838 as illustrated in FIG. 2. For example, as illustrated in FIG. A pair of area sensors in which pixels are arranged adjacent to each other may be used.
[0092]
In this case, the present invention can be applied similarly to the distance measuring sensor unit 83 by treating the area sensor as a plurality of line sensors extending in the X direction arranged adjacent to each other in the Y axis direction.
(2) In the above embodiment, when the depth of focus is deep, thinning-out ranging is performed with a wide range as the object to be measured. However, the present invention is not limited to this. First, thinning-out ranging is performed regardless of the focal length and the focal depth. Alternatively, all pixel ranging may be performed according to the ranging result and the depth of focus.
(3) In the above embodiment, the CMOS is used as the solid-state imaging device constituting the distance measuring sensor unit 83. However, the present invention is not limited to this. When reading, an image sensor which cannot read the same pixel data from the pixel again may be used.
[0093]
In this case, after the pixel data is once fetched from all the pixels, only the necessary pixel data (corresponding to the pixel data read from the line sensors 831 to 838 every other pixel in the above embodiment) is stored in the storage unit 98. It is preferable that the distance is stored and the distance is measured based on the stored pixel data.
[0094]
The imaging apparatus described above mainly includes the inventions described in the following supplementary notes 1 to 7.
[0095]
[Supplementary Note 1] An imaging apparatus, comprising: an imaging device that captures an optical image of a subject; and an imaging optical system that has a function of performing focus adjustment and that forms an optical image of the subject on an imaging surface of the imaging device. A plurality of distance measurement optical systems, a plurality of distance measurement sensors comprising a plurality of pixels arranged in at least one direction, provided in correspondence with each of the distance measurement optical systems, and each of the distance measurement sensors, A first distance measurement unit that specifies a plurality of pixels at every predetermined number of pixels and calculates a subject distance based on pixel data obtained from the pixels, and specifies a part of an imaging area in each of the distance measurement sensors Then, a second distance measuring unit that calculates a subject distance based on pixel data obtained from all pixels in the imaging region, and the first distance measuring unit or the second distance measuring unit according to a set imaging condition. Selection unit to select which of the distance measurement units to operate And a drive unit that causes the imaging optical system to perform focus adjustment based on the subject distance calculated by the selected distance measurement unit.
[0096]
[Supplementary Note 2] The apparatus further includes means for setting an exposure control value for the image sensor based on the brightness of a subject, and the imaging optical system is configured to be capable of changing a focal length. Information on the focal depth that changes according to the focal length of the system or the exposure control value, wherein the selecting unit selects one of the first and second distance measuring units according to the magnitude of the focal depth. An imaging device according to claim 1, wherein the imaging device is characterized in that:
[0097]
[Supplementary Note 3] The selection unit selects the first distance measurement unit when the depth of focus is smaller than a threshold value for the depth of focus, and selects the first distance measurement unit when the depth of focus is larger than the threshold value for the depth of focus. 3. The imaging apparatus according to claim 2, wherein the second distance measuring means is selected.
[0098]
According to the present invention, when the depth of focus is smaller than the threshold value for the depth of focus, by selecting the first distance measuring unit, it is possible to reliably detect a subject in a wide range as a distance measurement target. Compared with a configuration in which distance measurement is performed using pixel data obtained from all pixels of each distance measurement sensor, a storage capacity of a storage unit for shortening distance calculation time and storing pixel data for distance measurement Can be reduced.
[0099]
Further, when the depth of focus is larger than the threshold value for the depth of focus, by selecting the second ranging unit, high accuracy of ranging can be ensured, and from all pixels of each ranging sensor, Compared with a configuration in which distance measurement is performed using the obtained pixel data, it is possible to shorten the distance calculation time and reduce the storage capacity of the storage unit that stores the pixel data for distance measurement.
[0100]
[Supplementary Note 4] A finder for visually recognizing an imaging range of the imaging element is provided, and the second distance measurement unit converts pixel data of an image specified by an index indicating a distance measurement range provided in the finder. The imaging apparatus according to any one of supplementary notes 1 to 3, wherein the imaging distance is calculated using the imaging distance.
[0101]
[Supplementary Note 5] After calculating the subject distance by the first distance measuring unit, it is determined whether or not to calculate the subject distance by the second distance measuring unit based on the calculation result or / and the set imaging condition. When the determination unit determines that the second distance measuring unit calculates the subject distance, the second distance measuring unit is calculated by the first distance measuring unit. A part of the imaging area is designated in each distance measuring sensor based on the subject distance, and the subject distance is calculated based on pixel data obtained from all the pixels in the imaging area. An imaging device according to any one of the above.
[0102]
[Supplementary Note 6] The first distance measurement unit performs the calculation of the subject distance a plurality of times, and the determination unit detects that the subject is a moving object based on the calculation result by the first distance measurement unit. 6. The imaging apparatus according to claim 5, wherein it is determined that the subject distance is calculated by the second distance measuring unit.
[0103]
[Supplementary Note 7] The image forming apparatus according to any one of Supplementary Notes 1 to 6, wherein the partial imaging area specified by the second distance measuring unit is an imaging area on a center side of the distance measuring sensor. Imaging device.
[0104]
According to the present invention, the partial imaging region specified by the second distance measurement unit is the imaging region on the center side of the distance measurement sensor, so it is considered that there is a high possibility that the main subject exists. By imaging the main subject on the center side of the distance measurement sensor, the distance to the main subject can be accurately calculated.
[0105]
【The invention's effect】
According to the present invention, in each distance measuring sensor, a plurality of pixels are designated every predetermined number of pixels, and a first distance measuring unit that calculates a subject distance based on pixel data obtained from the pixels; A second distance measuring unit for designating a part of the imaging region in the distance measuring sensor and calculating a subject distance based on pixel data obtained from all pixels in the imaging region; Since one of the first and second distance measurement units is selected according to the depth, a distance measurement is performed in comparison with a configuration in which distance measurement is performed using pixel data obtained from all pixels of each distance measurement sensor. As a result, the distance measurement operation time can be reduced, and the storage capacity of the storage unit that stores the pixel data for distance measurement can be reduced.
[0106]
Further, according to the present invention, the second distance measuring unit is configured to calculate the subject distance using the pixel data of the image specified by the index indicating the distance measurement range provided in the finder, so The subject distance can be appropriately calculated according to the distance.
[0107]
According to the present invention, after calculating the object distance by the first distance measuring unit, whether or not to calculate the object distance by the second distance measuring unit based on the calculation result or / and the set imaging condition is determined. Is determined, and when it is determined that the subject distance is calculated by the second distance measuring unit, each of the distances is measured by the second distance measuring unit based on the object distance calculated by the first distance measuring unit. Since a part of the imaging area is specified in the distance sensor, and the object distance is calculated based on the pixel data obtained from all the pixels in the imaging area, the object distance can be calculated with higher accuracy than the first distance measurement unit. When it is necessary to calculate the subject distance, a more accurate subject distance can be obtained by calculating the subject distance by the second distance measuring unit.
[0108]
Further, according to the present invention, the subject distance is calculated a plurality of times by the first distance measuring unit, and the determining unit detects that the subject is a moving object based on the calculation result by the first distance measuring unit. Then, it is determined that the subject distance is to be calculated by the second distance measuring unit. Therefore, when it is determined that the subject is a moving object as a result of calculating the subject distance by the first distance measuring unit. Further, by calculating the subject distance by the second distance measuring unit, a more accurate subject distance can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of an imaging apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a distance measuring sensor unit according to the present embodiment.
FIG. 3 is a diagram for explaining a necessary distance measurement range according to a focal length.
FIG. 4 is a diagram for explaining thinned distance measurement and all pixel distance measurement.
FIG. 5 is a diagram for explaining thinned distance measurement and all pixel distance measurement.
FIG. 6 is a diagram for explaining a method of detecting a moving object in a moving object photographing mode.
FIG. 7 is a diagram for explaining thinned distance measurement and all-pixel distance measurement in the moving object imaging mode.
FIG. 8 is a flowchart illustrating a distance measuring process in the imaging apparatus.
FIG. 9 is a flowchart illustrating a distance measuring process in the imaging apparatus.
FIG. 10 is a diagram showing another configuration of the distance measuring sensor unit.
[Explanation of symbols]
1 Imaging device
2 Imaging optical system
3 Image sensor
4 Driver
5 Finder
6 Input operation unit
7 Photometry section
8 Distance measuring unit
81,82 Distance measuring optical system
83 Distance sensor
831-838 Line sensor
91 Metering information calculation unit
92 Focal length detector
93 Imaging control unit
94 Comparison section
95 Judgment unit
96 Distance information calculation section
97 Drive control unit
98 Memory
9 Control unit

Claims (5)

An imaging device that captures an optical image of a subject, and an imaging device including a function of performing focus adjustment and an imaging optical system that forms an optical image of the subject on an imaging surface of the imaging device,
A plurality of distance measuring optical systems,
A plurality of distance measurement sensors that are provided corresponding to each of the distance measurement optical systems and include a plurality of pixels arranged in at least one direction;
In each of the distance measurement sensors, a first distance measurement unit that specifies a plurality of pixels every predetermined number of pixels and calculates a subject distance based on pixel data obtained from the pixels.
In each of the distance measurement sensors, a second distance measurement unit that specifies a part of an imaging region and calculates a subject distance based on pixel data obtained from all pixels in the imaging region;
A selection unit that selects which of the first distance measurement unit and the second distance measurement unit is to be operated according to the set imaging condition;
An image pickup apparatus comprising: a drive unit that causes the image pickup optical system to perform focus adjustment based on the object distance calculated by the selected distance measuring unit. Means for setting an exposure control value for the imaging element based on the brightness of the subject; and the imaging optical system is configured to be capable of changing a focal length, and the imaging condition is a focal length of the imaging optical system. Or information on a depth of focus that changes according to an exposure control value, wherein the selection unit selects one of the first and second distance measurement units according to the magnitude of the depth of focus. Item 2. The imaging device according to Item 1. A finder for visually recognizing an image pickup range of the image pickup element, wherein the second distance measurement unit uses a pixel data of an image specified by an index indicating a distance measurement range provided in the finder to determine a subject distance. The imaging apparatus according to claim 1 or 2, wherein is calculated. After calculating the subject distance by the first ranging unit, a determining unit that determines whether to calculate the subject distance by the second ranging unit based on the calculation result or / and the set imaging condition. The second distance measurement unit is configured to calculate the object distance calculated by the first distance measurement unit when the determination unit determines that the object distance is calculated by the second distance measurement unit. 4. A method according to claim 1, wherein a part of an image pickup area is designated in each distance measuring sensor, and a subject distance is calculated based on pixel data obtained from all pixels in the image pickup area. An imaging device according to item 1. The first distance measurement unit performs the calculation of the subject distance a plurality of times, and the determination unit determines that the subject is a moving object based on the calculation result by the first distance measurement unit. The imaging apparatus according to claim 4, wherein it is determined that the subject distance is calculated by the distance measuring unit.

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