JP2010256776A - Image pickup device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup device having a high-speed auto-focusing function, and to provide an electronic apparatus. <P>SOLUTION: The image pickup device includes an optical element 10 for imaging and focusing an object Obj; an imaging unit 30 for picking up an image of the object Obj imaged by the optical element 10; and a pattern 20, provided between the optical element 10 and the imaging unit 30 to optically superimpose a pattern image h (x/k) on the image of the object Obj. The image pickup device makes a correlation operation for the image data, obtained from the imaging by the imaging unit 30 with a reference pattern corresponding to the pattern 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, an electronic device, and the like.

  The autofocus function (for example, the autofocus method disclosed in Patent Documents 1 and 2) is now an indispensable function as a camera function. Recently, the market for digital single-lens reflex cameras (DSLR) is on an expanding trend, and there is a growing need for higher performance and smaller size of digital single-lens reflex cameras. In response to this demand, there is a demand for autofocus technology that can autofocus at high speed and can reduce the size of the camera.

  For example, there is a phase difference AF method as a method that emphasizes high speed. In the phase difference AF method, the optical path is branched into two, an image sensor is provided in one optical path, and an AF dedicated sensor is provided in the other optical path. Then, the defocus amount is detected by the AF dedicated sensor, and focus control is performed using the detected defocus amount. However, when this phase difference AF method is used, a structure for branching the optical path (for example, a mirror) and a space for arranging the AF dedicated sensor are required, and it becomes difficult to reduce the size of the camera.

  Further, there is an imager AF method (contrast method) as a method that places importance on miniaturization. In the imager AF method, a focus position is obtained using an image sensor that performs normal imaging. That is, the contrast of the image obtained by the image sensor is used as an evaluation value, and the focus position is searched for using the fact that the contrast is highest at the in-focus position (mountain climbing method). However, in this imager AF method, since the contrast peak is searched by sequentially driving the focus lens, it is difficult to focus at high speed.

JP 2000-125177 A JP-A-8-124838

  According to some aspects of the present invention, it is possible to provide an imaging apparatus, an electronic device, and the like having a high-speed autofocus function.

  One embodiment of the present invention includes an optical element that focuses and focuses a subject, an imaging element that captures an image of the subject imaged by the optical element, and the optical element and the imaging element. Correlation calculation processing between a pattern provided in between for optically superimposing a pattern image on the image of the subject, image data obtained by imaging by the imaging device, and a reference pattern corresponding to the pattern And a correlation calculation unit that performs the processing.

  According to one aspect of the present invention, by providing a pattern between the optical element and the imaging element, the pattern image is superimposed on the subject image formed by the optical element. By capturing the subject image, image data of the subject image on which the pattern image is superimposed is acquired. The reference pattern is subjected to correlation calculation processing for the image data. Thereby, various processes using the processing result of the correlation calculation process and various functions can be realized.

  In one aspect of the present invention, a defocus information acquisition unit that acquires defocus information based on the evaluation value obtained by the correlation calculation process, and an autofocus control unit that performs focus control based on the defocus information And may be included.

  In this way, an autofocus function can be realized. Specifically, autofocus control can be performed by performing focus control based on defocus information acquired based on the evaluation value.

  In one aspect of the present invention, the defocus information acquisition unit determines a defocus direction based on the evaluation value obtained by the correlation calculation process, and the focus control unit includes the defocus information acquisition unit. Focus control may be performed based on the defocus direction determined by the above.

  In this way, information on the defocus direction can be acquired as defocus information by determining the defocus direction based on the evaluation value. The focus drive direction can be determined by performing focus control based on the acquired information on the defocus direction.

  In the aspect of the invention, the correlation calculation unit performs a correlation calculation process between the first reference pattern in which the spatial frequency monotonously increases in the first direction along the first coordinate axis and the image data. Obtaining a first evaluation value, performing a correlation operation between the second reference pattern in which the spatial frequency monotonously decreases in the first direction and the image data, and obtaining a second evaluation value, The defocus information acquisition unit may acquire defocus information based on the first and second evaluation values.

  In this way, defocus information can be acquired based on the first and second evaluation values. For example, in a certain defocus direction, a pattern image whose spatial frequency monotonously increases in the first direction is superimposed on the subject image. Then, the first reference pattern has a higher correlation with the pattern image. Due to this difference in correlation, the first and second evaluation values differ depending on the defocus direction, so that the defocus direction can be determined based on the first and second evaluation values.

  In one aspect of the present invention, the correlation calculation unit performs a correlation calculation process between the image data and a plurality of reference patterns corresponding to a plurality of pattern width reduction ratios, and the defocus information acquisition unit Based on the evaluation value obtained by the correlation calculation process, the pattern width reduction rate of the reference pattern having the highest correlation with the pattern image superimposed on the image data of the plurality of reference patterns is extracted and extracted. The defocus amount may be calculated based on the reduced pattern width reduction rate, and the focus control unit may perform focus control based on the defocus amount.

  According to one aspect of the present invention, by extracting the pattern width reduction rate of the reference pattern having the highest correlation with the pattern image and calculating the defocus amount based on the pattern width reduction rate, defocus information is obtained. Focus amount information can be acquired. Then, by performing focus control based on the acquired defocus amount information, it is possible to determine the focus drive amount based on the defocus amount.

  In one aspect of the present invention, the correlation calculation unit includes, as the plurality of reference patterns, a plurality of first reference patterns whose spatial frequencies monotonously increase in a first direction along a first coordinate axis; A plurality of second reference patterns whose spatial frequencies monotonously decrease in the first direction are input, and the correlation calculation unit performs a correlation calculation process between the image data and the plurality of first reference patterns. The first evaluation value is acquired, a correlation calculation process between the image data and the plurality of second reference patterns is performed to acquire a plurality of second evaluation values, and the defocus information acquisition unit Based on a plurality of first and second evaluation values, a pattern width reduction ratio of a reference pattern having the highest correlation with the pattern image superimposed on the image data among the plurality of reference patterns is extracted. Also good.

  In this way, the pattern width reduction rate of the reference pattern having the highest correlation with the pattern image can be extracted based on the plurality of first and second evaluation values. For example, first and second reference patterns corresponding to each pattern width reduction rate are generated. Then, first and second evaluation values corresponding to each pattern width reduction rate are obtained by the correlation calculation process. Since the first and second evaluation values differ depending on the pattern width reduction rate, the pattern width reduction rate of the reference pattern having the highest correlation with the pattern image can be extracted based on these evaluation values.

  In another aspect of the present invention, a spot light generation unit that irradiates a subject with spot light, an optical element that forms an image of the spot light irradiated on the subject, and the spot by the optical element An image pickup device for picking up an image of light, a pattern provided between the optical device and the image pickup device for optically superimposing a pattern image on the image of the spot light, and image pickup by the image pickup device This relates to an imaging apparatus including a correlation calculation unit that performs a correlation calculation process between the image data obtained by the above and a reference pattern corresponding to the pattern.

  According to another aspect of the present invention, the subject is irradiated with spot light, an image of the spot light is formed, and the pattern image is superimposed on the spot light image. By capturing the image, image data of the spot light image on which the pattern image is superimposed is acquired. The reference pattern is subjected to correlation calculation processing for the image data. Thereby, various processes using the processing result of the correlation calculation process and various functions can be realized.

  For example, in another aspect of the present invention, a defocus information acquisition unit that acquires defocus information based on the evaluation value obtained by the correlation calculation process, and a focus control unit that performs focus control based on the defocus information And may be included.

  In this way, an autofocus function can be realized. In addition, by irradiating the subject with spot light, it is possible to realize autofocus control regardless of a situation in which illumination such as natural light is obtained or a situation in which illumination is not obtained.

  In one embodiment and another embodiment of the present invention, the pattern and the reference pattern may be a chirp wave pattern.

  In this way, the correlation between the pattern image and the reference pattern is improved, and defocus information can be acquired with higher accuracy.

  Another aspect of the invention relates to an electronic apparatus including any of the imaging devices described above.

1 is a first basic configuration example of an imaging apparatus according to an embodiment. Explanatory drawing of a correlation calculation process. Explanatory drawing of a correlation calculation process. Explanatory drawing of a correlation calculation process. Explanatory drawing of a correlation calculation process. A specific configuration example of a watermark pattern. 1 is a first configuration example of an imaging apparatus according to an embodiment. Explanatory drawing of the acquisition method of a defocus amount. Explanatory drawing of the acquisition method of a defocus amount. Explanatory drawing of the acquisition method of a defocus amount. Explanatory drawing of the acquisition method of a defocus amount. 2 shows a second configuration example of an imaging apparatus according to the present embodiment. 2 shows a second basic configuration example of an imaging apparatus according to the present embodiment. Waveform example of the sync function. 3 shows a third configuration example of an imaging apparatus according to the present embodiment. Explanatory drawing of the acquisition method of a defocus amount. Explanatory drawing of operation | movement of the imaging device of the 3rd structural example. Configuration example of an electronic device.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Basic Configuration Example FIG. 1 shows a first basic configuration example of the imaging apparatus of the present embodiment. This imaging apparatus includes a lens 10 (optical element in a broad sense, an imaging optical system), a watermark pattern 20 (pattern in a broad sense), and an imaging element 30 (a photoelectric conversion element in a broad sense). Then, the pattern image by the watermark pattern 20 is superimposed on the subject image, and the apparatus is used for performing autofocus by using the superimposed pattern image.

  The lens 10 forms an image of the subject Obj and focuses (focuss) on the imaging surface. For example, the lens 10 includes a plurality of lenses such as an objective lens and a focus lens. Then, the focus lens is driven in the lens optical axis direction so that the focal point of the lens 10 is focused on the imaging surface of the imaging element 30. However, in the present embodiment, the lens 10 may be a single lens and may be focused by driving the lens. In the following, for convenience, the movement of the focus position (focal point, in-focus point) by driving the focus lens is indicated by the movement of the imaging surface in the optical axis direction.

  The watermark pattern 20 (special pattern, pattern portion) superimposes (superimposes) a pattern image on the image of the subject Obj. Specifically, the watermark pattern 20 is provided between the lens 10 and the image sensor 30. Then, the reflected light from the subject Obj is incident on the watermark pattern 20 through the lens 10 so that the pattern image of the watermark pattern 20 is superimposed on the image of the subject Obj. For example, the watermark pattern 20 is provided at least on the lens 10 side from the middle between the lens 10 and the image sensor 30. In order to appropriately superimpose a pattern image on an image corresponding to each point of the subject Obj, it is desirable that the watermark pattern 20 be provided at a position (near) as close to the lens 10 as possible. When the lens 10 is composed of a plurality of lenses, the watermark pattern 20 may be provided between the lenses. In other words, the watermark pattern 20 may be provided between the most objective lens of the plurality of lenses and the image sensor 30.

  More specifically, the watermark pattern 20 superimposes a pattern image with high autocorrelation on the image of the subject Obj. For example, as shown at A5, the watermark pattern 20 is formed by a binarized chirp wave pattern, and a pattern image of the chirp wave pattern (a pattern image shown by A1 in FIG. 1) is superimposed on the image of the subject Obj. The watermark pattern 20 may be configured by forming a pattern on a transparent flat plate, film, or the like (pattern member). The pattern is formed on the lens 10 by black film, ink, or the like (pattern member). It may be constituted by.

  The image of the subject Obj on which the pattern image is superimposed by the watermark pattern 20 is formed on the imaging surface of the imaging element 30. At this time, the pattern image on the imaging surface has a different width (pattern width) and orientation depending on the positional relationship between the imaging surface and the focus position. When the focus position is on the imaging surface (during focusing), the pattern image disappears. For example, as shown in FA1 of FIG. 1, when the imaging surface is at the defocus position, the pattern width on the imaging surface is a reduced width than the pattern width of the watermark pattern 20, as shown in A2. . As shown in FA2, when the imaging surface is located closer to the focus position than FA1, the pattern width on the imaging surface becomes a further reduced pattern width as shown in A3. As shown in FA3, when the imaging surface is at the defocus position in the previous focus state, the pattern image on the imaging surface is a pattern image obtained by inverting the watermark pattern 20 as shown in A4. That is, if the axis orthogonal to the optical axis of the lens 10 is the x-axis (first coordinate axis in a broad sense) and the watermark pattern 20 (transmittance of the watermark pattern 20) is represented by a function h (x), FA1, In the rear focus state indicated by FA2, the pattern image is represented by h (x / k). In the front focus state indicated by FA3, the pattern image is represented by h (−x / k) (k is the pattern width reduction rate). Here, the rear focus state is a state where the focus position is behind the imaging surface as viewed from the lens side, and the front focus state is a state where the focus position is in front of the imaging surface when viewed from the lens side.

  The image sensor 30 captures an image of the subject Obj on which the pattern image is superimposed by the watermark pattern 20. Then, image data is generated on the basis of an image signal obtained by imaging by the imaging element 30. For example, the image sensor 30 can be configured by a solid-state image sensor such as a CCD image sensor or a CMOS image sensor. These image sensors output an image signal (analog signal) of the captured image. Then, the image signal is subjected to A / D conversion processing (Analog to Digital Conversion), and image data of the captured image is generated.

2. Correlation Calculation Process and Defocus Information Acquisition Method The correlation calculation process and the defocus information acquisition method of this embodiment will be described with reference to FIGS.

As shown in FIG. 2, each point of an imaging region of the object Obj and _r 0 ~r _n. Then, the reflected light from each point _r 0 ~r _n is incident on the lens 10, an image corresponding to each point _r 0 ~r _n is imaged on the imaging surface of the imaging device 30. In this case, the image corresponding to each point r ₀ ~r _n, the pattern image by the watermark pattern 20, respectively, are superimposed. Therefore, the image formed on the imaging surface is an optical convolution of the pattern image with respect to the image of the subject Obj.

  For example, as shown in FB1 of FIG. 2, when the imaging surface is at the defocus position in the rear focus state, as shown in B1, a normal rotation pattern image h (x / k) with respect to the image of the subject Obj is obtained. Convolved. On the other hand, as shown in FB2, when the imaging surface is at the defocus position in the previous focus state, as shown in B2, an inverted pattern image h (−x / k) is convoluted with respect to the image of the subject Obj. The Then, as shown in B3 and B4, the reference pattern hs (x) (a function of the reference pattern) corresponding to the watermark pattern 20 is subjected to correlation calculation processing with respect to the image data of the image obtained by convolving the pattern image.

Specifically, as shown by C1 in FIG. 3, when the imaging surface is at the defocus position in the back focus state, the reflectance distribution r (x / m) of the subject Obj and the pattern image h (x / k) (m is the reduction ratio of the subject image). That is, it is represented by the following formula (1). Here, the symbol “*” represents a convolution operation (in the following equation (1), optical convolution).
fB (x, k) = r (x / m) * h (x / k) (1)

The reference pattern hs (x) is configured by a first reference pattern hs (x / ks) indicated by C2 and a second reference pattern hs (-x / ks) indicated by C3 (ks is a reference pattern) Reduction rate). hs (x / ks) is a reference pattern corresponding to the normal pattern image h (x / k), and hs (-x / ks) corresponds to the reverse pattern image h (-x / k). Reference pattern. Then, as shown in the following equation (2), a correlation calculation process is performed by performing a convolution calculation of these reference patterns on image data, and evaluation values V ₊ (x) and V ₋ (x) are obtained.
V ₊ (x) = fB (x, k) * hs (x / ks),
_{V - (x) = fB (} x, k) * hs (-x / ks) ··· (2)

On the other hand, as shown in FIG. 4, the image when the imaging surface is at the defocus position in the front focus state is expressed by the following expression (3), and the evaluation values V ₊ (x) and V ₋ (x) are It is represented by the following formula (4).
fF (x, k) = r (x / m) * h (−x / k) (3)
V ₊ (x) = fF (x, k) * hs (x / ks),
_{V - (x) = fF (} x, k) * hs (-x / ks) ··· (4)

Here, it is assumed that the reference pattern satisfies the following expression (5).
hs (x / ks) = h (x / k),
hs (−x / ks) = h (−x / k) (5)

Then, in the rear focus state, the following expression (6) is established from the above expressions (1) and (2).
V ₊ (x) = r (x / m) * h (x / k) * h (x / k),
_{V - (x) = r (} x / m) * h (x / k) * h (-x / k) ··· (6)

In the front focus state, the following expression (7) is established from the above expressions (3) and (4).
V ₊ (x) = r (x / m) * h (−x / k) * h (x / k),
_{V - (x) = r (} x / m) * h (-x / k) * h (-x / k) ··· (7)

At this time, when the inventors of the present application obtained V ₊ (x) and V ₋ (x) shown in the above formulas (6) and (7) by simulation, V ₋ (x) was changed to V ₊ (x). On the other hand, it has been found that a shift phenomenon occurs. Specifically, as shown by C4 in FIG. 3, in the rear focus state, V ₋ (x) is shifted from V ₊ (x) by the shift amount δ (+ δ) in the positive direction of the x axis. Further, as indicated by D1 in FIG. 4, in the previous focus state, V ₋ (x) is shifted from V ₊ (x) by the shift amount δ (−δ) in the negative direction of the x axis. The inventor of the present application has confirmed that V ₋ (x) shifts with respect to V ₊ (x) even when the above equation (5) is not satisfied (when ks = k is not satisfied).

As shown in FIG. 5, in this embodiment, the evaluation value V ₊ (x) and the evaluation value V ₋ (x) are subjected to correlation calculation to obtain the shift amount δ. Specifically, the correlation value S (s) is obtained by cross correlation calculation (Cross correlation) that integrates V ₊ (x) · V ₋ (x + s) with x. Then, s that maximizes the correlation value S (s) is obtained, and that s is set as the shift amount δ. For example, as shown in FIG. 5, when V ₋ (x) shifts by + δ with respect to V ₊ (x), s = + δ is obtained as s where the correlation value S (s) becomes the maximum value, and the shift amount s = + δ is set.

In the present embodiment, defocus information is acquired based on the shift of the evaluation values V ₊ (x) and V ₋ (x), and focus control is performed based on the acquired defocus information. For example, information on the defocus direction is acquired based on the shift direction. Specifically, when s> 0 (shift direction is the positive direction of the x axis), it is determined that the rear focus state is established, and when s <0 (shift direction is the negative direction of the x axis), It is determined that the state is the previous focus state. In addition, when s = 0 (s≈0), it is determined that the in-focus point is reached. Alternatively, as will be described later with reference to FIG. 8 and the like, information on the defocus amount is acquired based on the magnitude (absolute value) of the shift amount s. That is, the pattern width reduction rate k is estimated based on the magnitude of the shift amount s, and the distance between the position of the imaging surface and the focus position is obtained based on the k.

3. Watermark Pattern and Reference Pattern FIG. 6 shows a specific example of a watermark pattern. The watermark pattern 20 shown in FIG. 6 is a binarized version of the chirp wave pattern (sweep wave pattern) shown in E1. Specifically, as indicated by E1, the chirp wave pattern is represented by a trigonometric function in which the spatial frequency monotonously decreases (or monotonically increases) in the positive direction of the x axis. For example, as indicated by E2, the spatial frequency fx is represented by a trigonometric function that linearly (linearly or linearly) decreases in the positive direction of the x-axis. Then, in the range of x where the trigonometric function value is equal to or greater than a predetermined value (for example, positive), the high transmittance (first transmittance) is set, and the trigonometric function value is equal to or less than the predetermined value (for example, negative). In the range of x, the chirp wave pattern can be binarized by setting a low transmittance (second transmittance).

  As the reference pattern, a reference pattern in which the chirp wave pattern is binarized corresponding to the watermark pattern 20 is used. That is, if the reference pattern is represented by a function hs (x), for example, hs (x) = 1 (first value) for a range of x where the value of the trigonometric function of the chirp wave pattern is equal to or greater than a predetermined value. Corresponds. Further, for example, hs (x) = 0 (second value) corresponds to the range of x where the value of the trigonometric function is equal to or less than a predetermined value. The reference pattern corresponding to the pattern width reduction ratio ks is set to hs (x / ks) or hs (-x / ks) by replacing x with x / ks or -x / ks in the above hs (x). Is required. The reference pattern function hs (x) can be realized by a numerical table, for example.

4). First Configuration Example FIG. 7 shows a first configuration example of the imaging apparatus of the present embodiment. The imaging apparatus includes an imaging unit 100, a reference pattern generation unit 110, a correlation calculation unit 120 (convolution calculation unit), a defocus information acquisition unit 130 (image shift determination unit), a lens driving unit 140, and an autofocus control unit 150 ( A focus control unit), an image capturing unit 160, an image recording unit 170, and a monitor display unit 180. The imaging apparatus of the present invention is not limited to the configuration shown in FIG. 7, and various modifications such as omitting some of the components or adding other components are possible.

  The imaging unit 100 images a subject and outputs image data. Specifically, the imaging unit 100 includes an optical element, a watermark pattern, an imaging element, and an AFE (Analog Front End) circuit (not shown). The AFE circuit performs A / D conversion processing on the image signal from the image sensor to generate image data.

The reference pattern generation unit 110 generates a reference pattern corresponding to the watermark pattern. Specifically, reference patterns hs (x / ks) and hs (−x / ks) having a predetermined pattern width reduction rate ks (for example, ks = 2) are generated. The correlation calculation unit 120 performs correlation calculation processing. Specifically, a convolution operation (convolution integration) between the image data from the imaging unit 100 and the reference pattern is performed to obtain evaluation values V ₊ (x) and V ₋ (x). The defocus information acquisition unit 130 acquires defocus information based on the evaluation values V ₊ (x) and V ₋ (x). Specifically, based on the shift amount of the evaluation values V ₊ (x) and V ₋ (x), it is determined whether the focus is in the front focus state or the rear focus state (defocus direction). Based on the determination result, a front focus / rear focus determination signal (defocus direction determination signal) is output.

  The autofocus control unit 150 performs autofocus control and focus detection processing based on the defocus information from the defocus information acquisition unit 130. Specifically, the autofocus control unit 150 performs control to move the focus position backward when the front focus / rear focus determination signal indicates the front focus state. Further, when the front focus / rear focus determination signal indicates the rear focus state, control for moving the focus position forward is performed. The lens driving unit 140 drives the focus lens. Specifically, the lens driving unit 140 receives a control signal from the autofocus control unit 150 and moves the focus position forward or backward. The image capturing unit 160 captures image data from the image capturing unit 100 at the time of focusing, and outputs the captured image data to the image recording unit 170. Specifically, the image capturing unit 160 receives an in-focus confirmation signal generated by the auto-focus control unit 150 detecting the in-focus, and captures image data.

  The image recording unit 170 records the image data from the image capturing unit 160. For example, the image recording unit 170 can be configured by a semiconductor memory or an optical drive. The monitor display unit 180 displays image data from the image capturing unit 160 or the image recording unit 170. For example, the monitor display unit 180 can be configured by a liquid crystal display (LCD) or an EL (Electro-Luminescence) display.

  Here, in a digital camera such as a digital single-lens reflex camera, there is a problem that an autofocus function capable of performing autofocus at high speed with a small configuration is required. For example, in the phase difference AF method, high-speed autofocus is possible, but it is difficult to reduce the size because an optical path branching unit and an AF dedicated sensor are required. In addition, the imager method (contrast method) can be miniaturized, but high-speed autofocus is difficult because the focus position is obtained in an exploratory manner.

  In this regard, according to the present embodiment, the lens 10 forms an image of the subject Obj, the watermark pattern 20 optically superimposes the pattern image on the image of the subject Obj, and the image sensor 30 superimposes the pattern image. The captured image of the subject Obj is captured, and the correlation calculation unit 120 performs a correlation calculation process between the image data obtained by the imaging and the reference pattern.

  In the present embodiment, the defocus information acquisition unit 130 acquires defocus information based on the evaluation value obtained by the correlation calculation process, and the autofocus control unit 150 performs focus control based on the defocus information. I do.

  In this way, the defocus information is acquired based on the evaluation value, and the focus control is performed based on the defocus information, whereby the autofocus function can be realized. Further, according to the present embodiment, since the optical path branching means and the AF dedicated sensor are not required unlike the phase difference AF method, the configuration can be made compact. Thereby, size reduction of a camera can be achieved.

  In the present embodiment, the defocus information acquisition unit 130 determines the defocus direction based on the evaluation value, and the autofocus control unit 150 performs focus control based on the defocus direction.

  In this way, defocus direction information can be acquired as defocus information. Then, by performing focus control based on the defocus direction, the focus drive direction can be determined directly. As a result, the autofocus can be speeded up as compared with the imager method in which the focus drive direction is determined in an exploratory manner.

  In the present invention, one reference pattern may be generated as a reference pattern and one evaluation value may be obtained as an evaluation value. A plurality of reference patterns may be generated as a reference pattern and a plurality of evaluation values may be obtained as evaluation values. May be.

For example, in the present embodiment, first and second reference patterns hs (x / ks) and hs (−x / ks) are generated as reference patterns, and the first and second evaluation values V ₊ are generated by correlation calculation processing. (X) and V ₋ (x) are obtained. In this way, by obtaining the shift amount δ of the evaluation values V ₊ (x) and V ₋ (x), the defocus direction can be determined based on the sign of the shift amount δ.

In this embodiment, as will be described later with reference to FIG. 8 and the like, the defocus information acquisition unit 130 calculates the defocus amount based on the evaluation values V ₊ (x) and V ₋ (x), and performs autofocus control. The unit 150 may perform focus control based on the defocus amount.

  In this way, the defocus amount can be acquired as the defocus information, and the distance between the imaging surface and the focus position can be detected. Therefore, by performing focus control based on the defocus amount, for example, the focus lens can be driven to the in-focus point by one focus drive. As a result, the autofocus can be speeded up as compared with the imager method in which the focus drive direction is determined in an exploratory manner.

In the present embodiment, the correlation calculation unit 120 uses the first reference pattern hs (x (x) in which the spatial frequency monotonously increases in the first direction (positive direction or negative direction) along the x-axis (first coordinate axis). / Ks) and the image data are subjected to correlation calculation processing to obtain the first evaluation value V ₊ (x). In addition, the second reference pattern hs (−x / ks) in which the spatial frequency monotonously decreases in the first direction and image data are subjected to correlation calculation processing to obtain the second evaluation value V ₋ (x). . The defocus information acquisition unit 130 acquires defocus information based on the first and second evaluation values V ₊ (x) and V ₋ (x).

For example, as indicated by C2 and C3 in FIG. 3, hs (x / ks) in which the spatial frequency monotonously increases in the positive direction of the x axis and hs (−x /) in which the spatial frequency monotonously decreases in the positive direction of the x axis. ks) is used. At this time, it is assumed that the spatial frequency of the pattern image monotonously increases in the positive direction of the x-axis as indicated by C1. Then, hs (x / ks) has a higher correlation than hs (−x / ks) for this pattern image. Therefore, the evaluation values V ₊ (x) and V ₋ (x) cause a difference such as a shift, and defocus information can be acquired based on the difference.

  In the present embodiment, as described with reference to FIG. 6, a chirp wave pattern may be used as such a reference pattern. This chirp wave pattern is a pattern with high autocorrelation. That is, the correlation is very high with respect to a pattern having the same shape as that of the self, compared to other patterns such as a subject image and a reverse pattern. Therefore, by using a chirp wave pattern for the watermark pattern and the reference pattern, the difference in correlation between hs (x / ks) and hs (−x / ks) becomes larger, and defocus information can be acquired with higher accuracy. It becomes like this.

5). Defocus Amount Acquisition Method A defocus amount acquisition method will be described in detail with reference to FIGS. As shown in FIG. 8, it is assumed that the imaging surface of the imaging device 30 is at the defocus position indicated by F1. At this time, the distance between the focus position indicated by F2 and the imaging surface is d, and the distance between the pattern 20 and the imaging surface is di. The distance d is a defocus amount at the defocus position indicated by F1. Further, since the positions of the pattern 20 and the image sensor 30 are fixed inside the image pickup apparatus, the distance di is known. In the following, the pattern width of the pattern 20 is set to 1 for the sake of simplicity.

As shown in FIG. 9, first to nth pattern width reduction ratios k1 to kn (a plurality of pattern width reduction ratios, where n is a natural number) are set as the pattern width reduction ratio ks of the reference pattern. Corresponding to k1 to kn, reference patterns hs (x / k1) to hs (x / kn) and hs (−x / k1) to hs (−x / kn) are generated. Then, hs (x / k1) to hs (x / kn) are subjected to a convolution operation on the captured image data r (x / m) * h (x / k), whereby the evaluation value V1 ₊ (x ) To Vn ₊ (x). Further, hs (−x / k1) to hs (−x / kn) are subjected to a convolution operation on the captured image data r (x / m) * h (x / k), so that the evaluation value V1 _{− (x)} ~Vn - (x) is obtained.

Then, shift amounts + δ1 to + δn (or −δ1 to −δn) are obtained based on the evaluation values V1 ₊ (x) to Vn ₊ (x) and V1 ₋ (x) to Vn ₋ (x). For example, _V1 - from the shift amount + .delta.1 is obtained for _V1 + (x) of (x), _Vn - is _Vn + from the shift amount for (x) + .DELTA.n of (x) are determined.

  As shown in FIG. 10, different shift amounts + δ1 to + δn are obtained according to the pattern width reduction ratios k1 to kn. This is because the correlation between the reference pattern and the pattern image is different when the pattern width reduction rate of the reference pattern is different. Then, the maximum value + δi (i is a natural number between 1 and n) of the shift amount δ is detected, and the pattern width reduction rate ki corresponding to + δi is obtained. When the correlation between the reference pattern and the pattern image is maximum, it is considered that the shift amount is also maximized. Therefore, ki is the pattern width reduction rate closest to the pattern width reduction rate k of the pattern image. In this way, the pattern width reduction rate k (= ki) of the pattern image is obtained.

FIG. 11 is an explanatory diagram showing the relationship between the pattern width reduction ratio k and the defocus amount d. In FIG. 11, the position of the imaging surface and the focus position are indicated by the same symbols F1 and F2 as in FIG. As shown in FIG. 11, since 1 / k is proportional to d, the following equation (8) is established.
tan θ = (1-1 / k) / di = (1 / k) / d (8)

Then, the following equation (9) is derived from the above equation (8).
d = di · 1 / (k−1) (9)
By the above equation (9), the defocus amount d is obtained based on the pattern width reduction rate k of the pattern image and the known distance di.

6). Second Configuration Example FIG. 12 shows a second configuration example of the imaging apparatus of the present embodiment. The imaging apparatus includes an imaging unit 100, a reference pattern generation unit 110, a correlation calculation unit 120 (convolution calculation unit), a defocus information acquisition unit 130, a lens driving unit 140, an autofocus control unit 150, an imaging capture unit 160, An image recording unit 170 and a monitor display unit 180 are included. In addition, the same code | symbol is attached | subjected to components, such as a monitor display part demonstrated in FIG. 7, etc., and description is abbreviate | omitted suitably.

  The imaging device of the second configuration example is a device for acquiring a defocus amount and a defocus direction as defocus information and performing autofocus control based on the defocus amount and defocus direction.

Specifically, the reference pattern generation unit 110 receives the pattern width reduction rates k1 to kn from the correlation calculation unit 120, and the reference patterns hs (x / k1) to hs (x / kn) corresponding to k1 to kn, hs (-x / k1) to hs (-x / kn) are generated. The correlation calculation unit 120 is a convolution of the image data from the imaging unit 100 and the reference patterns hs (x / k1) to hs (x / kn), hs (−x / k1) to hs (−x / kn). Perform the operation. Then, the correlation calculation unit 120 calculates the shift amounts δ1 to δn based on the evaluation values V1 ₊ (x) to Vn ₊ (x) and V1 ₋ (x) to Vn ₋ (x) obtained by the convolution calculation. Ask.

  The defocus information acquisition unit 130 acquires information on the defocus amount and the defocus direction based on the shift amounts δ1 to δn. Specifically, the defocus information acquisition unit 130 includes a matching pattern width detection unit 200, an image shift determination unit 210, and a defocus amount calculation unit 220. The adaptive pattern width detection unit 200 detects the maximum value δi (maximum absolute value) of the shift amounts δ1 to δn, and extracts the pattern width reduction rate ki corresponding to the maximum value δi. The image shift determination unit 210 determines the defocus direction based on the shift amount δi, and outputs a defocus direction determination signal. Specifically, the image shift determination unit 210 determines that the rear focus state is satisfied when δi> 0, and the front focus state is satisfied when δi <0. The defocus amount calculation unit 220 calculates the defocus amount based on the pattern width reduction rate ki. Specifically, the defocus amount d is obtained by the above equation (9).

  The autofocus control unit 150 receives the defocus amount d and the defocus direction determination signal and performs autofocus control. Specifically, the autofocus control unit 150 controls the drive direction of the focus drive (the moving direction of the focus position) based on the defocus direction determination signal, and the focus drive drive amount (focus) based on the defocus amount d. Controls the distance of movement of the position.

  As described above, according to the present embodiment, a plurality of reference patterns corresponding to a plurality of pattern width reduction ratios k1 to kn are subjected to correlation calculation processing on image data, and evaluation values corresponding to k1 to kn are obtained. It is done. Then, the pattern width reduction rate ki of the reference pattern having the highest correlation with the pattern image is extracted based on the evaluation value.

  In this way, the pattern width reduction rate k of the pattern image on the imaging surface can be obtained. That is, ki can be extracted as the pattern width reduction ratio closest to the pattern width reduction ratio k of the pattern image among k1 to kn. Thereby, the defocus amount d of the imaging surface can be known by calculating the defocus amount d based on ki. Then, by performing focus control based on the obtained defocus amount d, the focus position can be adjusted with respect to the imaging surface at high speed.

  In the present invention, as a plurality of reference patterns corresponding to k1 to kn, one reference pattern may be generated for each of k1 to kn, and a plurality of reference patterns are generated for each of k1 to kn. May be.

For example, in this embodiment, as a plurality of reference patterns corresponding to k1 to kn, a plurality of first reference patterns hs (x / k1) to hs (x / kn) and a plurality of second reference patterns hs ( -X / k1) to hs (-x / ks) are generated. Then, a plurality of first evaluation values V1 ₊ (x) to Vn ₊ (x) and a plurality of second evaluation values V1 ₋ (x) to Vn ₋ (x) are acquired by the correlation calculation process, and the shift amount δ1 to δn are obtained. In this way, by obtaining the pattern width reduction rate ki corresponding to the maximum value δi of δ1 to δn, the pattern width reduction rate ki of the reference pattern having the highest correlation with the pattern image can be extracted.

7). Illumination with Spot Light FIG. 13 shows a second basic configuration example of the imaging apparatus of the present embodiment. The imaging apparatus includes a lens 10, a watermark pattern 20, an imaging element 30, and a spot light generation unit 40. The components such as the lens described in FIG. 1 and the like are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The spot light generation unit 40 irradiates the subject Obj with a spot light SP (pointing beam). Specifically, the spot light generation unit 40 includes a light source 50 and an irradiation unit 60. The light source 50 generates a beam for irradiating spot light, and is configured by, for example, an LED or a semiconductor laser. The irradiation unit 60 reflects or refracts the beam from the light source 50 and irradiates the subject Obj. For example, the irradiation unit 60 is configured by a mirror or a prism. On / off of the spot light SP irradiated by the spot light generation unit 40 may be controlled by a control circuit (not shown) (for example, an autofocus control unit).

  The spot light SP illuminates one point (or a plurality of points) on the subject Obj, for example. At this time, the reflected light of the spot light SP is imaged by the lens 10, so that one pattern image corresponding to the spot light SP is formed on the imaging surface of the imaging element 30. This pattern image is represented by p · h (x / k) in the rear focus state, and is represented by p · h (−x / k) in the front focus state. p is the reflectance of the subject Obj with respect to the spot light SP. On the other hand, an image by illumination other than spot light such as natural light or active illumination is also formed on the imaging surface. This image is represented by r (x / m) * h (x / k) in the rear focus state and represented by r (x / m) * h (−x / k) in the front focus state.

In the present embodiment, an image when the spot light is turned off and an image when the spot light is turned on are captured. For example, in the rear focus state, the image _{fB N-1 (x, k} ) to be captured when the off spot light and the image fB N being imaged when turned on the spot light _(x, k), under It is represented by Formula (10).
fB _N-1 (x, k) = r (x / m) * h (x / k),
fB _N (x, k) = r (x / m) * h (x / k) + p · h (x / k)
(10)

Then, as shown in the following equation (11), the difference between the image data obtained by capturing these images is calculated, and as shown in the following equation (12), the convolution between the difference and the reference pattern is calculated. An evaluation value is obtained by calculation.
gB _N (x, k) = fB _N (x, k) −fB _N−1 (x, k) (11)
V ₊ (x) = gB _N (x, k) * hs (x / ks),
_{V - (x) = gB N} (x, k) * hs (-x / ks) ··· (12)

Table On the other hand, in the rear focus state, the image _fF when the off spot light _N-1 (x, k) and the image _fF N (x, k) when the on-spot light, the following equation (13) Is done. The difference gF _N (x, k) is expressed by the following expression (14), and the evaluation values V ₊ (x) and V ₋ (x) are expressed by the following expression (15).
fF _N-1 (x, k) = r (x / m) * h (−x / k),
fF _N (x, k) = r (x / m) * h (−x / k) + p · h (−x / k)
(13)
gF _N (x, k) = fF _N (x, k) −fF _N−1 (x, k) (14)
V ₊ (x) = gF _N (x, k) * hs (x / ks),
_{V - (x) = gF N} (x, k) * hs (-x / ks) ··· (15)

Here, it is assumed that the reference pattern satisfies the following expression (16), and the watermark pattern and the reference pattern are chirp wave patterns.
hs (x / ks) = h (x / k),
hs (−x / ks) = h (−x / k) (16)

In the convolution calculation between chirp wave patterns, the relationship of the following equation (17) is established. The function sinc (x) is a sink function shown in FIG.
h (x / k) * h (x / k) = h (−x / k) * h (−x / k) = sinc (x),
h (x / k) * h (−x / k) = 0 (17)

Then, from the above equations (10) to (17), the following equation (18) is established in the rear focus state, and the following equation (19) is established in the front focus state. Further, since the pattern image disappears at the time of focusing, the following equation (20) is established.
V ₊ (x) = p · h (x / k) * h (x / k) = p · sinc (x),
_{V - (x) = p ·} h (x / k) * h (-x / k) = 0
(18)
V ₊ (x) = p · h (−x / k) * h (x / k) = 0,
_{V - (x) = p ·} h (-x / k) * h (-x / k) = p · sinc (x)
(19)
V ₊ (x) = V ₋ (x) = 0 (20)

In this embodiment, based on the above equations (18) to (20), when V ₊ (x)> 0 and V ₋ (x) = 0, it is determined that the rear focus state, V ₊ (x) = 0, V _- (x)> is determined that pre-focus state when _{0, V + (x) =} V - by determining the focus position when the (x) = 0, determines the defocus direction. Since the pixel value of the image data is positive data, in the present invention, the evaluation values of the above formulas (18) to (20) may be values including an offset. In the present invention, the watermark pattern and the reference pattern may be patterns other than the chirp wave pattern, and ks may be a value other than k. At this time, _V + at the rear focus state (x), before _V in focus state - (x) may be a different function p · sinc (x).

Here, the case where the subject Obj is illuminated by natural light other than the spot light has been described above. However, in the present invention, autofocus control can be performed even when there is no illumination other than spot light, such as night photography with a camera or imaging with an endoscope. In this case, imaging is performed at the time of spot light irradiation, and the captured image is expressed by the following equation (21).
fB (x, k) = p · h (x / k),
fF (x, k) = p · h (−x / k) (21)

  Accordingly, by calculating the evaluation value by convolution calculation of the image data and the reference pattern, the same calculation results as the above formulas (18) to (20) can be obtained. In this way, the defocus direction can be determined by the same method as described above.

8). Third Configuration Example FIG. 15 shows a third configuration example of the imaging apparatus according to the present embodiment. The imaging apparatus includes an imaging unit 100, a reference pattern generation unit 110, a correlation calculation unit 120 (autocorrelation calculation unit), a defocus information acquisition unit 130, a lens driving unit 140, an autofocus control unit 150, an imaging capture unit 160, An image recording unit 170 and a monitor display unit 180 are included. In addition, the same code | symbol is attached | subjected to components, such as a monitor display part demonstrated in FIG. 7, etc., and description is abbreviate | omitted suitably.

  The imaging apparatus of the third configuration example is an apparatus for acquiring defocus information based on a subject image obtained by irradiating a subject with spot light and performing autofocus control based on the defocus information. is there.

The imaging unit 100 includes a spot light generation unit 40 for irradiating a subject with spot light. The reference pattern generation unit 110 receives the pattern width reduction ratios k1 to kn from the correlation calculation unit 120 and receives reference patterns hs (x / k1) to hs (x / kn), hs (−x / k1) to hs ( -X / kn). The correlation calculation unit 120 performs a convolution calculation between the reference pattern and the image data from the imaging unit 100, and evaluates values V1 ₊ (x) to Vn ₊ (x), V1 ₋ (x) to Vn ₋ (x). Ask for.

The defocus information acquisition unit 130 acquires defocus information based on the evaluation value from the correlation calculation unit 120. Specifically, the defocus information acquisition unit 130 includes a defocus direction detection unit 230, a suitable pattern width detection unit 200, and a defocus amount calculation unit 220. The defocus direction detection unit 230 determines the defocus direction based on the evaluation value, and outputs a defocus direction determination signal. For example, based on the sign of an arbitrary set of evaluation values V1 ₊ (x) to Vn ₊ (x), V1 ₋ (x) to Vn ₋ (x) (for example, V1 ₊ (x) and V1 ₋ (x)). The front focus state, rear focus state, and in-focus state are determined. The adaptive pattern width detection unit 200 detects the pattern width reduction rate k of the pattern image. Specifically, peak values p1 to pn corresponding to k1 to kn are obtained based on the evaluation values. That is, the peak values of V1 ₊ (x) to Vn ₊ (x) are obtained in the rear focus state, and the peak values of V1 ₋ (x) to Vn ₋ (x) are obtained in the front focus state. Then, based on p1 to pn, a pattern width reduction ratio kj (j is a natural number between 1 and n) closest to the pattern width reduction ratio k of the pattern image among k1 to kn is extracted. The defocus amount calculation unit 220 calculates the defocus amount based on kj. Specifically, the defocus amount d is obtained by the calculation method described in FIG.

  The kj acquisition method will be specifically described with reference to FIG. As shown in FIG. 16, different values are acquired as p1 to pn according to k1 to kn. Then, the matching pattern width detection unit 200 detects the maximum value pj of p1 to pn, and extracts the pattern width reduction rate kj corresponding to pj, thereby extracting kj closest to the pattern width reduction rate k of the pattern image. To do. Here, p1 to pn differ according to k1 to kn because the correlation between the reference pattern and the pattern image differs according to k1 to kn. The correlation between the reference pattern and the pattern image is highest when the pattern width reduction ratios match. Further, the higher the correlation between the reference pattern and the pattern image, the sharper the peak of the evaluation value (for example, the peak of the sync function when using a chirp wave pattern). Therefore, kj closest to the pattern width reduction rate k of the pattern image can be extracted by detecting the maximum value pj of p1 to pn.

  FIG. 17 is a diagram for explaining the operation of the imaging apparatus according to the present embodiment. As indicated by G1 in FIG. 17, the spot light is turned on (turned on) in the first frame f1, and as shown by G2, imaging by the imaging element is performed. As indicated by G3, the spot light is turned off (turned off) in the second frame f2, and as indicated by G4, imaging by the imaging element is performed. And defocus information is acquired based on the image imaged in f1 and f2. If it is determined to be defocused, focus drive is performed as shown in G5.

  Similarly, in the third frame f3, imaging is performed with the spot light turned on, and defocus information is acquired based on the images captured in f2 and f3. If it is determined to be defocused, focus driving is performed again. Such focus control is repeated until focusing is achieved. For example, assume that it is determined to be in focus in the fifth frame f5 as indicated by G6. Then, as shown in G7, the focus confirmation signal is activated, and the image captured at f5 is recorded.

  In the description of the third configuration example, it is assumed that evaluation values corresponding to a plurality of pattern width reduction ratios are obtained, and information on the defocus amount and the defocus direction is acquired based on the evaluation values. . However, in the present invention, an evaluation value corresponding to one pattern width reduction rate may be obtained, and only information on the defocus direction may be acquired based on the evaluation value.

  Here, according to the present embodiment, the spot light generation unit 40 irradiates the subject Obj with the spot light SP, and the lens 10 forms an image of the spot light SP irradiated on the subject Obj. However, the pattern image is optically superimposed on the image of the spot light SP, and the image sensor 30 captures the image of the spot light SP. Then, the correlation calculation unit 110 performs a correlation calculation process between the image data obtained by imaging and the reference pattern corresponding to the watermark pattern 20.

  In this way, the autofocus function can be realized even when the subject is not illuminated. Specifically, by irradiating the subject with spot light, an image of the spot light on which the pattern image is superimposed can be taken. Then, the defocus information can be acquired by performing correlation calculation processing on the image data obtained by the imaging and the reference pattern. In this manner, defocus information can be acquired and autofocus control can be performed even when the subject is not illuminated.

Further, according to the present embodiment, the defocus information acquisition process can be simplified. For example, as described in the above formulas (18) to (20), the defocus direction can be determined based on the magnitude relationship between the evaluation values V ₊ (x) and V ₋ (x). As described above, the defocus direction can be determined without further processing the evaluation values V ₊ (x) and V ₋ (x).

9. Electronic Device FIG. 18 shows a configuration example of an electronic device including the imaging device of the present embodiment. The electronic device includes a camera module 910 (imaging device), a display control device 920, a host controller 940, a driver 950 (display driver), and an electro-optical panel 960. Various modifications such as omission of some of these constituent elements and addition of other constituent elements are possible.

  The camera module 910 includes an optical element, a watermark pattern, an imaging element, and the like, and performs autofocus control and imaging. The display control circuit 920 supplies the image data supplied from the camera module 910, a horizontal synchronization signal, a vertical synchronization signal, and the like to the driver 950. The host controller 940 is a CPU, for example, and receives the operation information from the operation input unit 970 and controls the camera module 910, the display control circuit 920, and the driver 950. The electro-optical panel 960 is, for example, a liquid crystal panel or an EL panel, and displays an image by driving a driver 950. The operation input unit 970 is for a user to input various information, and is realized by various buttons, a keyboard, and the like.

  In addition, as an electronic device implement | achieved by this embodiment, various apparatuses, such as a digital camera, a digital video camera, a portable information terminal, a mobile telephone, a portable game terminal, a WEB camera, can be assumed, for example.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, in the specification or the drawings, terms (lens, watermark pattern, image sensor) described at least once together with different terms (optical element, pattern, photoelectric conversion element, correlation operation, first coordinate axis, etc.) in a broader sense or the same meaning , Convolution operations, x-axis, etc.) can be replaced by the different terms anywhere in the specification or drawings. Further, the configurations and operations of the correlation calculation unit, the defocus information acquisition unit, the imaging device, the electronic device, and the like are not limited to those described in the present embodiment, and various modifications can be made.

10 optical elements, 20 patterns, 30 imaging elements, 40 spot light generation units,
50 light sources, 60 irradiation units, 100 imaging units, 110 reference pattern generation units,
120 correlation calculation unit, 130 defocus information acquisition unit, 140 lens driving unit,
150 autofocus control unit, 160 imaging capture unit, 170, image recording unit,
180 monitor display unit, 200 compatible pattern width detection unit,
210 image shift determination unit, 220 defocus amount calculation unit,
230 defocus direction detection unit, 910 camera module,
920 display control circuit, 940 host controller, 950 driver,
960 electro-optical panel, 970 operation input unit,
Obj subject, h (x / k) pattern image, hs (x / ks) reference pattern,
k, ks pattern width reduction ratio, V ₊ (x) evaluation value, d defocus amount

Claims (10)

An optical element for imaging and focusing a subject;
An image sensor that captures an image of the subject imaged by the optical element;
A pattern provided between the optical element and the imaging element for optically superimposing a pattern image on the image of the subject;
A correlation calculation unit that performs correlation calculation processing between image data obtained by imaging with the imaging element and a reference pattern corresponding to the pattern;
An imaging apparatus comprising: In claim 1,
A defocus information acquisition unit that acquires defocus information based on the evaluation value obtained by the correlation calculation process;
An autofocus control unit that performs focus control based on the defocus information;
An imaging apparatus comprising: In claim 2,
The defocus information acquisition unit
A defocus direction is determined based on the evaluation value obtained by the correlation calculation process,
The focus control unit
An image pickup apparatus that performs focus control based on the defocus direction determined by the defocus information acquisition unit. In any one of Claims 1 thru | or 3,
The correlation calculation unit includes:
The first reference pattern in which the spatial frequency monotonically increases in the first direction along the first coordinate axis and the image data are subjected to correlation calculation processing to obtain a first evaluation value, and the first direction To obtain a second evaluation value by performing a correlation calculation process between the second reference pattern in which the spatial frequency monotonously decreases and the image data,
The defocus information acquisition unit
An imaging apparatus, wherein defocus information is acquired based on the first and second evaluation values. In any one of Claims 1 thru | or 3,
The correlation calculation unit includes:
Performing correlation calculation processing between the image data and a plurality of reference patterns corresponding to a plurality of pattern width reduction rates;
The defocus information acquisition unit
Based on the evaluation value obtained by the correlation calculation process, extract the pattern width reduction rate of the reference pattern having the highest correlation with the pattern image superimposed on the image data of the plurality of reference patterns, Calculate the defocus amount based on the extracted pattern width reduction rate,
The focus control unit
An image pickup apparatus that performs focus control based on the defocus amount. In claim 5,
In the correlation calculation unit,
As the plurality of reference patterns, a plurality of first reference patterns whose spatial frequency monotonically increases in a first direction along a first coordinate axis, and a plurality of second reference patterns whose spatial frequency monotonously decreases in the first direction. Is entered,
The correlation calculation unit includes:
A correlation calculation process between the image data and the plurality of first reference patterns is performed to obtain a plurality of first evaluation values, and a correlation calculation process between the image data and the plurality of second reference patterns is performed. To obtain a plurality of second evaluation values,
The defocus information acquisition unit
Based on the plurality of first and second evaluation values, a pattern width reduction ratio of the reference pattern having the highest correlation with the pattern image superimposed on the image data among the plurality of reference patterns is extracted. An imaging apparatus characterized by that. A spot light generator for irradiating the subject with spot light;
An optical element for forming an image of the spot light irradiated on the subject;
An image sensor that captures an image of the spot light by the optical element;
A pattern provided between the optical element and the imaging element for optically superimposing a pattern image on the spotlight image;
A correlation calculation unit that performs a correlation calculation process between the image data obtained by imaging by the imaging element and a reference pattern corresponding to the pattern;
An imaging apparatus comprising: In claim 7,
A defocus information acquisition unit that acquires defocus information based on the evaluation value obtained by the correlation calculation process;
A focus control unit that performs focus control based on the defocus information;
An imaging apparatus comprising: In claims 1 to 8,
The pattern and the reference pattern are:
An image pickup apparatus having a chirp wave pattern.   An electronic apparatus comprising the imaging device according to claim 1.

Images