JP2020101626A - Imaging device - Google Patents

Abstract

To provide an imaging device that can capture images having subjects on a reference plane focused, as suppressing increase in ISO sensitivity.SOLUTION: A controller 180 of a digital camera 100 is configured to cause (a) a focus lens drive unit 122 to move a focus lens 112 so as to have the focus lens focused on a first prescribed position P1 on a reference plane of a subject; (b) then, cause the focus lens drive unit 122 to move the focus lens 112 so as to make a focus position move from the first prescribed position P1 to a second prescribed position P2 on the basis of a position relationship between the first prescribed position P1 and the second prescribed position P2 whose height from the reference plane on an optical axis is a prescribed height; and (c) cause an image pick-up element tilting unit 160 to tilt an imaging plane of an image pick-up element 130 so that a focus plane is parallel with respect to the reference plane, and is a plane located at a prescribed height.SELECTED DRAWING: Figure 8

Description

The present disclosure relates to an imaging device having a tilt photographing function.
The present invention relates to an imaging device.

Patent Document 1 discloses an image pickup apparatus having a tilt photographing function using the Scheimpflug principle.

JP, 2017-173802, A

According to the imaging device having the tilt photographing function using the Scheimpflug principle, for example, by tilting the lens, it is possible to image the competition from an obliquely upper position such as a stand seat of a stadium such as volleyball, soccer, or track and field. In this case, an in-focus image can be captured from the front side to the back side of the floor surface (reference plane) of the stadium.

However, if the player focuses on the floor, the upper part of the player who plays on the floor may not fit within the depth of field and the upper part may be blurred. In this case, it is possible to focus on the upper side by narrowing the aperture of the optical system to increase the depth of field. However, when the shutter speed cannot be changed, the ISO sensitivity is reduced by the aperture. It is necessary to raise it, and the noise on the captured image increases.

The present disclosure provides an imaging device that can obtain an image in which a subject on a reference plane is in focus while suppressing an increase in ISO sensitivity.

An image pickup apparatus according to a first aspect of the present disclosure includes an image pickup element that picks up a subject image formed on an image pickup surface to generate image data, and an optical system that includes a focus lens and forms a subject image on the image pickup surface. , A focus lens drive unit that drives the focus lens in the optical axis direction, an image sensor tilting unit that rotates and tilts the imaging surface of the image sensor about an axis that is not parallel to the optical axis, a focus lens drive unit, and an image sensor tilt And a control unit that controls the unit. The control unit (a) moves the focus lens to the focus lens drive unit so as to focus on the first predetermined position on the reference plane of the subject, and then (b) adjusts the height from the reference plane on the optical axis. Based on the positional relationship between the second predetermined position and the first predetermined position having a predetermined height, the focus lens drive unit is caused to move the focus lens so as to move the focus position from the first predetermined position to the second predetermined position. Further, (c) the image pickup surface of the image pickup element is tilted by the image pickup element tilting portion so that the focus surface becomes a plane parallel to the reference plane and at a position of a predetermined height.

An image pickup apparatus according to a second aspect of the present disclosure includes an image pickup element that picks up a subject image formed on an image pickup surface to generate image data, and an optical system that includes a focus lens and forms a subject image on the image pickup surface. , A focus lens drive unit for driving the focus lens in the optical axis direction, an optical system tilting unit for rotating and tilting the principal point surface of the optical system about an axis that is not parallel to the optical axis, a focus lens drive unit, and an optical system. And a control unit that controls the tilting unit. The control unit (a) moves the focus lens to the focus lens drive unit so as to focus on the first predetermined position on the reference plane of the subject, and then (b) adjusts the height from the reference plane on the optical axis. Based on the positional relationship between the second predetermined position and the first predetermined position having a predetermined height, the focus lens drive unit is caused to move the focus lens so as to move the focus position from the first predetermined position to the second predetermined position. And, (c) the principal point surface of the optical system is tilted by the optical system tilting portion so that the focus surface becomes a plane parallel to the reference plane and at a predetermined height.

According to the imaging device of the present disclosure, it is possible to obtain an image in which a subject on the reference plane is in focus while suppressing an increase in ISO sensitivity.

FIG. 2 is a diagram showing a configuration of the digital camera according to the first embodiment. The figure which showed an example of a structure of an image sensor tilting part. Figure showing an example of the tilt shooting setting screen Flowchart explaining the flow of tilt shooting operation The figure explaining the calculation method of the tilt angle φ0 of the imaging surface. Diagram illustrating focusing within the depth of field The figure explaining the calculation method of the optical axis direction distance t2. The figure explaining the calculation method of the tilt angle φ1′ of the imaging surface. The figure explaining the calculation method of the aperture value F which implement|achieves the depth of field set on the tilt photographing setting screen. FIG. 3 is a diagram showing a configuration of a digital camera according to a second embodiment. Diagram showing an example of the configuration of the optical system tilting unit Flowchart explaining the flow of tilt shooting operation The figure explaining the calculation method of the tilt angle φ0 of the principal point surface. The figure explaining the calculation method of the optical axis direction distance t2. The figure explaining the calculation method of the tilt angle φ1 of the principal point surface. The figure explaining the calculation method of the aperture value F which implement|achieves the depth of field set on the tilt photographing setting screen. Diagram illustrating the problems of the present disclosure Diagram illustrating the problems of the present disclosure Diagram illustrating the problems of the present disclosure

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed description of well-known matters and duplicate description of substantially the same configuration may be omitted. This is for avoiding unnecessary redundancy in the following description and for facilitating understanding by those skilled in the art. It should be noted that the inventor (s) provide the accompanying drawings and the following description for those skilled in the art to fully understand the present disclosure, and intend to limit the subject matter described in the claims by these. Not something to do.

(Background of disclosure)
17 to 19 are diagrams illustrating the problem of the present disclosure. For example, in a case where a game such as volleyball is imaged from an obliquely upper position such as a stand seat around a volleyball court (stadium), in a general image pickup apparatus, as shown in FIG. When focusing on the position P1 (for example, the center line), the focusing surface is inclined with respect to the floor surface. As a result, the portion outside the range of the depth of field before and after the focus surface is out of focus and is blurred. In such a case, it is possible to focus substantially from the front side to the back side of the floor of the stadium by narrowing down the aperture to deepen the depth of field. However, if the aperture is greatly reduced, it is necessary to increase the ISO sensitivity (gain) depending on shooting conditions, and noise on the image increases.

If the image pickup apparatus as in Patent Document 1 is used, the principal point plane of the optical system (perpendicular to the optical axis of the optical system and By appropriately tilting a plane including the "lens principal point"), it is possible to focus without squeezing the aperture from the front side to the back side of the floor surface (an example of the reference plane) of the stadium. In addition, it is possible to focus similarly by tilting the image pickup surface (sensor surface) of the image pickup element.

However, when focusing on the floor surface, as shown in FIG. 18, only the upper part (front side) of the depth of field can be used as shown in FIG. 18, so the upper part (head side) of the player who plays on the floor surface. ) May not fit within the depth of field and the top may be blurred. In this case, the upper part of the optical system can be focused substantially by narrowing the aperture of the optical system to increase the depth of field. However, when the shutter speed cannot be changed, the ISO sensitivity is increased by the amount of the aperture reduction. It is necessary to increase the noise on the captured image.

When the inventor of the present application diligently studied the above problem, as shown in FIG. 19, by setting the focus surface above the floor surface, a portion of the depth of field below the focus surface (rear side). It has also been found that the above can be effectively used and the above problems can be solved.

However, in order to realize this, a new problem arises as to how to set the focus surface at a height position above the floor surface where no object exists. The present disclosure also solves this problem.

(Embodiment 1)
Hereinafter, embodiments of an imaging device according to the present disclosure will be described with reference to the drawings.

1-1. Configuration FIG. 1 is a block diagram showing the configuration of the digital camera 100 according to the first embodiment.

The digital camera 100 includes an optical system 110, an image sensor 130, a liquid crystal monitor 220, a controller 180, a card slot 190, and the like.

The optical system 110 includes a zoom lens 111, a focus lens 112, and a diaphragm 113.

The zoom lens 111 is a lens for changing the magnification of a subject image formed on the image sensor 130 by the optical system 110. The zoom lens 111 is composed of one or a plurality of lenses. The zoom lens drive unit 121 includes a zoom ring that can be operated by the user, transmits the operation by the user to the zoom lens 111, and moves the zoom lens 111 along the optical axis direction of the optical system 110.

The focus lens 112 is a lens for changing the focus state of a subject image formed on the image sensor 130 by the optical system 110. The focus lens 112 is composed of one or a plurality of lenses.

The focus lens drive unit 122 includes a motor and moves the focus lens 112 along the optical axis of the optical system 110 under the control of the controller 180. The focus lens driving unit 122 can be realized by a DC motor, a stepping motor, a servo motor, an ultrasonic motor, or the like.

The diaphragm 113 is an element that adjusts the amount of light incident on the image sensor 130. The diaphragm 113 includes, for example, a plurality of diaphragm blades, and adjusts the size of the opening formed by the diaphragm blades to adjust the amount of light incident on the image sensor 130.

The diaphragm drive unit 123 drives the diaphragm 113. The diaphragm drive unit 123 can be realized by a DC motor, a stepping motor, a servo motor, an ultrasonic motor, or the like.

The image sensor 130 captures a subject image incident through the optical system 110 to generate image data. The generated image data is digitized by an AD converter (Analog-to-Digital Converter (ADC)) 140. The image sensor 130 operates at a timing controlled by a timing generator (Timing Generator (TG)) 150. Examples of the operation of the image sensor 130 include a still image capturing operation and a through image capturing operation. The through image is mainly a moving image, and is displayed on the liquid crystal monitor 220 for the user to determine a composition for capturing a still image.

The image sensor 130 is a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, or the like.

The liquid crystal monitor 220 displays the image represented by the display image data that has been image-processed by the controller 180. The liquid crystal monitor 220 has a touch sensor function. The user can perform various settings for the digital camera 100 by performing a touch operation on the operation screen displayed on the liquid crystal monitor 220.

The controller 180 controls the overall operation of the digital camera 100 by controlling the components such as the image sensor 130 according to an instruction from the release button 210. The controller 180 sends the vertical synchronization signal to the timing generator 150. In parallel with this, the controller 180 generates an exposure synchronization signal. The controller 180 uses a built-in memory 230 (including a DRAM (Dynamic Random Access Memory)) as a work memory during a control operation or an image processing operation. The controller 180 performs predetermined image processing on the image data digitized by the AD converter 140. The predetermined image processing is, for example, gamma correction processing, white balance correction processing, flaw correction processing, YC conversion processing, electronic zoom processing, or JPEG (Joint Photographic Experts Group) compression processing.

The controller 180 may be composed of a hard-wired electronic circuit, or may be composed of a microcomputer using a program. For example, the controller 180 may be a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), an ASIC (Application Integrated Circuit), or a DSP (Digital Signal) or the like.

The memory card 200 can be mounted in the card slot 190. The card slot 190 controls the memory card 200 under the control of the controller 180. The digital camera 100 can store image data in the memory card 200 and read image data from the memory card 200.

The digital camera 100 according to the present embodiment further includes an image sensor tilting unit 160 and a tilt angle sensor 170.

FIG. 2 is a diagram showing an example of the configuration of the image sensor tilting unit 160. Note that, in FIG. 2, a lens 110A in which a plurality of lenses such as a zoom lens 111 and a focus lens 112 included in the optical system 110 are integrated into one is shown.

The image sensor tilting unit 160 rotates and tilts the image pickup surface (sensor surface) of the image pickup element 130 about an x axis (an axis that is perpendicular to the optical axis and is on the image pickup surface (an example of an axis that is not parallel to the optical axis)). Let In the example of FIG. 2, the image sensor tilting unit 160 is provided with a movable plate 163 to which the image sensor 130 is fixed, and a fixed frame 161 which is respectively arranged before and after the movable plate 163 and fixed to a housing member of the digital camera 100. , 162. Coils 168 and 169 are fixed to the movable plate 163, and magnets 164, 165, 166 and 167 are fixed to the fixed frames 161 and 162 at positions facing the coils 168 and 169. Although not shown in FIG. 2, the tilt angle sensor 170 described above is attached to the movable plate 163. By controlling the current flowing to the coils 168, 169, the attraction force and repulsion force between the coils 168, 169 and the magnets 164, 165, 166, 167 are changed to move the movable plate 163 around the x-axis. The fixed frames 161 and 162 can be rotated and tilted. Accordingly, the image pickup surface of the image pickup device 130 can be rotated around the x axis and tilted. It should be noted that the image sensor tilting unit 160 may be configured in any manner as long as the image sensor surface of the image sensor 130 can be rotated and tilted about an axis that is not parallel to the optical axis. For example, the image sensor tilting unit 160 may use a stepping motor, a voice coil motor, or another actuator. When a stepping motor is used as the actuator, open control can be performed, and accordingly, the tilt angle sensor 170 can be omitted.

The tilt angle sensor 170 is a sensor for detecting the tilt angle of the imaging surface of the image sensor 130. The tilt angle sensor 170 can be realized by, for example, a magnet and a Hall element.

The controller 180 uses the touch sensor function of the liquid crystal monitor 220 to set information about the camera height, camera depression angle, focus surface height, and depth of field set by the user, and the signal from the tilt angle sensor 170. Then, the image sensor tilting unit 160 is controlled.

1-2. Operation The digital camera 100 of the present embodiment has a tilt photographing function of tilting the image pickup surface of the image pickup device 130 to take an image. The tilt photographing function will be described below. Here, for ease of understanding, as a specific example, a case will be described in which the digital camera 100 is installed above a stand seat in a stadium such as volleyball or soccer and shooting is performed.

FIG. 3 is a diagram showing an example of the tilt photographing setting screen.

Before using the tilt photographing function, the user uses the touch sensor function of the liquid crystal monitor 220 to display the tilt photographing setting screen (GUI) of FIG. The tilt shooting setting screen displays input windows for camera height, camera depression angle, focus surface height, and depth of field, and an execution button. The user inputs the camera height, the camera depression angle, the focus surface height, and the depth of field, and touches the execution button. Note that the focus surface height and the depth of field are set to values desired by the user. When the execute button is touched, the controller 180 stores the input information (tilt shooting setting information) in the built-in memory 230. Here, the camera height is the height from the floor surface of the stadium (an example of a reference plane) to the principal point of the optical system 110 (hereinafter referred to as “lens principal point”). In the second embodiment described later, the camera height is the height from the floor surface of the stadium to the center of the image pickup surface of the image pickup device 130. The camera depression angle is an angle formed by the optical axis of the optical system 110 and the horizontal direction when the optical system 110 of the camera is directed to the first predetermined position (center line or the like) of the stadium. The focus surface height is the height from the floor surface of the stadium to the focus surface. The depth of field is the depth of field in the direction perpendicular to the floor surface of the stadium (vertical direction).

FIG. 4 is a flowchart explaining the flow of the tilt photographing operation.

When the tilt photographing function is activated, the controller 180 reads the tilt photographing setting information set on the tilt photographing setting screen of FIG. 3 from the built-in memory 230 (S11).

The controller 180 calculates the tilt angle φ0 of the imaging surface for making the focus surface perpendicular to the floor surface and including the first predetermined position P1 (S12).

FIG. 5 is a diagram illustrating a method of calculating the tilt angle φ0 of the imaging surface. According to the Scheimpflug principle, in order to make the focus plane perpendicular to the floor plane and including the first predetermined position P1, the extension line of the imaging plane and the extension line of the principal point plane are on this vertical focus plane. You only have to intersect at one point. In the present embodiment, by tilting the image pickup surface from the state shown by the broken line parallel to the principal point plane to the state shown by the solid line, the extension line of the image pickup surface is made the intersection of the extension line of the principal point plane and the focus plane. Let them intersect. The tilt angle φ0 of the imaging surface at this time is equal to the included angle (φ0) around the intersection of the extension line of the imaging surface and the extension line of the principal point surface.

The tilt angle φ0 can be calculated by Expression 1.

ここで、ｆは光学系１１０の焦点距離、θはデジタルカメラ１００の俯角（カメラ俯角）、Ｈｃは床面から光学系１１０のレンズ主点までの距離（カメラ高さ）である。ｆの値は、内蔵メモリ２３０に予め格納されている。θとしては、チルト撮影設定画面で設定されたカメラ俯角が用いられる。Ｈｃとしては、チルト撮影設定画面で設定されたカメラ高さが用いられる。

Here, f is the focal length of the optical system 110, θ is the depression angle of the digital camera 100 (camera depression angle), and Hc is the distance from the floor surface to the lens principal point of the optical system 110 (camera height). The value of f is stored in the built-in memory 230 in advance. As θ, the camera depression angle set on the tilt photographing setting screen is used. As Hc, the camera height set on the tilt photographing setting screen is used.

The controller 180 causes the image pickup device tilting unit 160 to tilt the image pickup device 130 so that the tilt angle of the image pickup surface becomes φ0 (S13). As a result, the focus surface becomes perpendicular to the floor surface.

Here, in AF control by contrast detection, the position where the contrast value is maximum is set as the focus position (focus position), but within the depth of field, the detected contrast value is the same or almost the same value. As a result, as shown in FIG. 6, even if the first predetermined position P1 (for example, the center line) on the floor is not completely in focus (not in focus), focus is achieved. The controller may determine that it is doing so. Therefore, in the present embodiment, the image pickup device tilting unit 160 tilts the image pickup device 130 so that the tilt angle of the image pickup surface is φ0, and the focus surface is made perpendicular to the floor surface, so that the image pickup surface is parallel to the floor surface. The depth of field in the direction is made shallow. This improves the accuracy of focusing on the first predetermined position P1 on the floor surface.

The controller 180 causes the focus lens driving unit 122 to move the focus lens 112 so that the contrast value of the image output from the image sensor 130 is maximized (S14). That is, the controller 180 performs autofocus control for focusing on the first predetermined position P1.

When moving the focus lens 112 in step S14, if the aperture 113 is not in the aperture open state, the focus lens 112 may be moved after the aperture 113 is driven so as to be in the aperture open state. After moving the focus lens 112, the aperture value is returned to the original aperture value (aperture value to be used at the time of shooting) from the aperture open. By thus setting the aperture 113 in the aperture open state when performing the autofocus control, the depth of field becomes shallower, and the accuracy of focusing on the first predetermined position P1 on the floor surface can be further improved. it can. By changing the aperture value closer to the full aperture value than the original aperture value, the depth of field becomes shallow and the focusing accuracy can be further improved. Here, if the aperture value becomes too bright by changing the aperture value to the aperture open side, the shutter speed may be increased and/or the ISO sensitivity may be decreased.

The controller 180 moves the focus position from the first predetermined position P1 to the second predetermined position P2 where the height from the floor surface is the height H (focus surface height) on the optical axis. A distance t2 on the optical axis from the lens to the lens principal point (hereinafter referred to as "optical axis direction distance") is calculated (S15).

FIG. 7 is a diagram illustrating a method of calculating the optical axis direction distance t2. 7A shows the state before moving the focus position, and FIG. 7B shows the state after moving the focus position.

The optical axis direction distance t2 can be calculated by Expression 2.

ここで、ｆは光学系１１０の焦点距離、θはデジタルカメラ１００の俯角（カメラ俯角）、ｔ１は、ステップＳ１４のオートフォーカス制御でフォーカスレンズ１１２が移動した後(コントローラが合焦していると判断したとき)の撮像面中心からレンズ主点までの光軸方向距離、Ｈはピント面の床面からの距離（ピント面高さ）である。ｆの値は、内蔵メモリ２３０に予め格納されている。θとしては、チルト撮影設定画面で設定されたカメラ俯角が用いられる。Ｈとしては、チルト撮影設定画面で設定されたピント面高さが用いられる。

Here, f is the focal length of the optical system 110, θ is the depression angle (camera depression angle) of the digital camera 100, and t1 is after the focus lens 112 is moved by the autofocus control in step S14 (when the controller is in focus). In the optical axis direction from the center of the image pickup surface (when determined) to the principal point of the lens, H is the distance of the focus surface from the floor surface (focus surface height). The value of f is stored in the built-in memory 230 in advance. As θ, the camera depression angle set on the tilt photographing setting screen is used. As H, the focus surface height set on the tilt photographing setting screen is used.

The optical axis direction distance t1 used in Equation 2 can be obtained by the following method. Specifically, the digital camera 100 detects the position of the focus lens 112 in the optical axis direction based on a sensor, a focus motor control amount, and the like. The built-in memory 230 stores information on the distance in the optical axis direction from the center of the imaging surface to the lens principal point in association with the position in the optical axis direction. These can be stored, for example, in a table. The controller 180 detects the position of the focus lens 112 in the optical axis direction when focused on the first predetermined position P1, and based on the detected position of the optical axis direction, the optical axis direction from the center of the imaging surface to the lens principal point. The distance is read from the built-in memory 230. Then, the controller 180 uses the read distance in the optical axis direction as the distance t1 in the optical axis direction in Expression 2.

The controller 180 causes the focus lens driving unit 122 to move the focus lens 112 so that the distance in the optical axis direction from the center of the imaging surface to the lens principal point is t2 (S16). For example, the optical axis direction position corresponding to the optical axis direction distance t2 is obtained by referring to the table, and the focus lens 112 is moved to the obtained position. As a result, the focus position is moved from the first predetermined position P1 to the second predetermined position P2 based on the positional relationship between the second predetermined position P2 and the first predetermined position P1.

The controller 180 calculates the tilt angle φ1 of the imaging surface for making the focus surface parallel to the floor surface and at the height H (focus surface height) (S17).

FIG. 8 is a diagram illustrating a method of calculating the tilt angle φ1 of the imaging surface. According to the Scheimpflug principle, in order to make the focus surface parallel to the floor surface and at a height H (focus surface height), on the focus surface at this height H (focus surface height) The extension line of the imaging surface and the extension line of the principal point surface may intersect at one point. In the present embodiment, by tilting the image pickup surface from the state shown by the broken line parallel to the principal point plane to the state shown by the solid line, the extension line of the image pickup surface is made the intersection of the extension line of the principal point plane and the focus plane. Let them intersect. The tilt angle φ1 of the imaging surface at this time is equal to the included angle (φ1) around the intersection of the extension line of the imaging surface and the extension line of the principal point surface.

The tilt angle φ1 can be calculated by Expression 3.

ここで、ｆは光学系１１０の焦点距離、θはデジタルカメラ１００の俯角（カメラ俯角）、Ｈｃは床面から光学系１１０のレンズ主点までの距離（カメラ高さ）、Ｈはピント面の床面からの距離（ピント面高さ）である。ｆの値は、内蔵メモリ２３０に予め格納されている。θとしては、チルト撮影設定画面で設定されたカメラ俯角が用いられる。Ｈｃとしては、チルト撮影設定画面で設定されたカメラ高さが用いられる。Ｈとしては、チルト撮影設定画面で設定されたピント面高さが用いられる。

Here, f is the focal length of the optical system 110, θ is the depression angle of the digital camera 100 (camera depression angle), Hc is the distance from the floor surface to the lens principal point of the optical system 110 (camera height), and H is the focus surface. It is the distance from the floor surface (focus surface height). The value of f is stored in the built-in memory 230 in advance. As θ, the camera depression angle set on the tilt photographing setting screen is used. As Hc, the camera height set on the tilt photographing setting screen is used. As H, the focus surface height set on the tilt photographing setting screen is used.

The controller 180 causes the image pickup device tilting unit 160 to tilt the image pickup device 130 so that the tilt angle of the image pickup surface becomes φ1 (S18). Thereby, as shown in FIG. 8, the focusing surface becomes parallel to the floor surface. In addition, the upper edge and the lower edge of the depth of field range are parallel to the focus surface and the floor surface (state that can be regarded as parallel). Note that the depth of field on the front side (upper side) and the depth of field on the rear side (lower side) of the focus surface are strictly different, but in the above-described usage modes such as at a stadium, Even if the center of the depth of field in the depth direction is regarded as the focus surface, no serious problem occurs. Therefore, here, the center in the depth direction of the depth of field is set as the focus surface.

Here, in order to realize the depth of field set on the tilt shooting setting screen when the focus surface is raised to the position of the focus surface height H as described above, the aperture value F of the aperture 113 is opened. May have to be set to a higher value. The method of calculating the aperture value F for realizing the depth of field set on the tilt shooting setting screen will be described below. The timing at which the diaphragm 113 is driven so as to obtain the calculated diaphragm value F is, for example, after the execution of step S18.

FIG. 9 is a diagram illustrating a method of calculating the aperture value F that realizes the depth of field (D2) set on the tilt shooting setting screen.

The aperture value F can be calculated by Expression 4.

ここで、ｆは光学系１１０の焦点距離、δは最小錯乱円径（撮像素子に依存する固定値）、θはデジタルカメラ１００の俯角（カメラ俯角）、Ｆは絞り１１３の絞り値、Ｈｃは床面から光学系１１０のレンズ主点までの距離（カメラ高さ）、Ｈはピント面の床面からの距離（ピント面高さ）である。ｆの値は、内蔵メモリ２３０に予め格納されている。θとしては、チルト撮影設定画面で設定されたカメラ俯角が用いられる。Ｈｃとしては、チルト撮影設定画面で設定されたカメラ高さが用いられる。Ｈとしては、チルト撮影設定画面で設定されたピント面高さが用いられる。

Here, f is the focal length of the optical system 110, δ is the minimum confusion circle diameter (fixed value depending on the image sensor), θ is the depression angle (camera depression angle) of the digital camera 100, F is the aperture value of the aperture 113, and Hc is The distance from the floor surface to the principal point of the lens of the optical system 110 (camera height), and H is the distance from the floor surface to the focus surface (focus surface height). The value of f is stored in the built-in memory 230 in advance. As θ, the camera depression angle set on the tilt photographing setting screen is used. As Hc, the camera height set on the tilt photographing setting screen is used. As H, the focus surface height set on the tilt photographing setting screen is used.

1-3. Effects, etc. As described above, the digital camera 100 of the present embodiment includes the image sensor 130 that captures a subject image formed on the imaging surface to generate image data, and the focus lens 112, and the subject image on the imaging surface. An optical system 110 that forms an image, a focus lens driving unit 122 that drives the focus lens 112 in the optical axis direction, and an image sensor tilt that rotates and tilts the imaging surface of the image sensor 130 about an axis that is not parallel to the optical axis. The unit 160 and a controller 180 (control unit) that controls the focus lens driving unit 122 and the image sensor tilting unit 160. The controller 180 causes (a) the focus lens drive unit 122 to move the focus lens 112 so as to focus on the first predetermined position P1 on the floor surface (an example of a reference plane) of the subject, and then (b) the optical axis. The focus position is moved from the first predetermined position P1 to the second predetermined position P2 based on the positional relationship between the second predetermined position P2 and the first predetermined position P1 at which the height from the floor surface becomes the predetermined height. The focus lens 112 is moved to the focus lens driving unit 122, and then (c) the image sensor tilting unit 160 is set so that the focus surface becomes a plane parallel to the floor and at a position of a predetermined height. The image pickup surface of the image pickup device 130 is tilted.

According to the digital camera 100 of the present embodiment having such a configuration, it is possible to perform tilt photographing effectively using both the front side portion and the rear side portion of the depth of field. Therefore, it is possible to obtain an image in which the subject on the floor is in focus while suppressing an increase in ISO sensitivity.

In the present embodiment, before executing (a), the controller 180 images the imaging element tilting unit 160 so that the focusing surface is a plane that is perpendicular to the floor surface and includes the first predetermined position P1. The imaging surface of the element 130 is tilted.

As a result, the depth of field in the direction parallel to the floor centering around the first predetermined position P1 becomes shallow. Therefore, in (a), when the focus lens 112 is moved to the focus lens driving unit 122 to focus on the first predetermined position P1, it is possible to improve the accuracy of focusing on the first predetermined position P1.

In the present embodiment, a liquid crystal monitor 220 (an example of an operation unit) that receives an input of the focus surface height (predetermined height) is further provided.

This allows the user to appropriately set a desired height as the focus surface height in accordance with the height of the subject.

In the present embodiment, a liquid crystal monitor 220 (an example of a second operation unit) that receives an input of a desired depth of field is further provided.

This allows the user to appropriately set the desired depth of field in accordance with the height of the subject.

(Embodiment 2)
In the first embodiment, the image pickup surface of the image pickup device 130 is tilted during tilt photographing, but in the second embodiment, the principal point surface of the optical system 110 is tilted.

2-1. Configuration FIG. 10 is a diagram showing the configuration of the digital camera according to the second embodiment.

The digital camera 100A of the present embodiment includes an optical system tilting unit 300 and a tilt angle sensor 350 instead of the image sensor tilting unit 160 of the digital camera 100 of the first embodiment. In the following, differences from the first embodiment will be mainly described.

The optical system tilting section 300 tilts the entire optical system 110.

FIG. 11 is a diagram showing an example of the configuration of the optical system tilting unit 300. Note that, in FIG. 11, a lens 110A in which a plurality of lenses such as a zoom lens 111 and a focus lens 112 included in the optical system 110 are integrated into one is shown.

The optical system tilting unit 300 rotates and tilts the principal point surface of the optical system 110 about an x axis (an axis that is perpendicular to the optical axis and is on the imaging surface (an example that is not parallel to the optical axis)). In the example of FIG. 11, the optical system tilting unit 300 includes a housing frame 310 that houses the lens barrel 110B that holds the optical system 110, and an actuator 320 that is interposed between the housing frame 310 and the lens barrel 110B. .. The housing frame 310 includes a holding shaft 311 that holds the lens barrel 110B rotatably around the x axis. The actuator 320 includes a piston 321 that moves up and down by an electromagnetic solenoid or the like, and its tip is connected to one end side of the lens barrel 110B in the optical axis direction. With such a configuration, by vertically moving the piston 321 of the actuator 320, the lens barrel 110B can be rotated around the x-axis and tilted. As a result, the principal point plane of the optical system 110 can be rotated around the x axis and tilted. The optical system tilting unit 300 may have any configuration as long as it can rotate and tilt the principal point surface of the optical system 110 about an axis that is not parallel to the optical axis. For example, the optical system tilting unit 300 may be configured by a stepping motor, a voice coil motor, or another actuator. When a stepping motor is used as the actuator, open control can be performed, and accordingly, the tilt angle sensor 350 can be eliminated.

The tilt angle sensor 350 is a sensor for detecting the tilt angle of the principal point surface of the optical system 110. The tilt angle sensor 350 can be realized by, for example, a magnet and a Hall element.

2-2. Operation FIG. 12 is a flowchart illustrating the flow of the tilt photographing operation. It should be noted that steps having the same contents as those in the first embodiment will be described as appropriate so that the flow of operation can be easily understood. The same steps as those in the first embodiment are designated by the same reference numerals, and different steps are denoted by different reference numerals.

When the tilt photographing function is activated, the controller 180 reads the tilt photographing setting information set on the tilt photographing setting screen of FIG. 3 from the built-in memory 230 (S11).

The controller 180 calculates the tilt angle φ0 of the principal point surface for making the focus surface perpendicular to the floor surface and including the first predetermined position P1 (S12A).

FIG. 13 is a diagram illustrating a method of calculating the tilt angle φ0 of the principal point surface. According to the Scheimpflug principle, in order to make the focus plane perpendicular to the floor plane and including the first predetermined position P1, the extension line of the imaging plane and the extension line of the principal point plane are on this vertical focus plane. You only have to intersect at one point. In the present embodiment, by tilting the principal point surface from the state shown by the broken line parallel to the imaging surface to the state shown by the solid line, the extension line of the principal point surface becomes the intersection of the extension line of the imaging surface and the focus surface. Let them intersect. The tilt angle φ0 of the principal point surface at this time is equal to the included angle (φ0) around the intersection of the extension line of the imaging surface and the extension line of the principal point surface.

The tilt angle φ0 can be calculated by the above-mentioned formula 1.

In the present embodiment, Hc is the distance from the floor surface to the center of the image pickup surface of the image pickup device 130 (camera height).

The controller 180 drives the lens by the optical system tilting unit 300 so that the tilt angle of the principal point surface becomes φ0 (S13A).

The controller 180 causes the focus lens driving unit 122 to move the focus lens 112 so that the contrast value of the image output from the image sensor 130 is maximized (S14). That is, the controller 180 performs autofocus control for focusing on the first predetermined position P1.

The controller 180 moves the focus position from the first predetermined position P1 to the second predetermined position P2 where the height from the floor surface is the height H (focus surface height) on the optical axis, and the center of the imaging plane. The distance t2 from the to the lens principal point in the optical axis direction is calculated (S15).

FIG. 14 is a diagram illustrating a method of calculating the optical axis direction distance t2. FIG. 14A shows the state before moving the focus position, and FIG. 14B shows the state after moving the focus position.

The optical axis direction distance t2 can be calculated by the above-described mathematical expression 2.

The controller 180 causes the focus lens driving unit 122 to move the focus lens 112 so that the distance in the optical axis direction from the center of the imaging surface to the lens principal point is t2 (S16). As a result, the focus position is moved from the first predetermined position P1 to the second predetermined position P2 based on the positional relationship between the second predetermined position P2 and the first predetermined position P1.

The controller 180 calculates the tilt angle φ1 of the principal point surface for making the focus surface parallel to the floor surface and at the height H (focus surface height) (S17A).

FIG. 15 is a diagram illustrating a method of calculating the tilt angle φ1 of the principal point surface. According to the Scheimpflug principle, in order to make the focus surface parallel to the floor surface and at a height H (focus surface height), on the focus surface at this height H (focus surface height) The extension line of the imaging surface and the extension line of the principal point surface may intersect at one point. In the present embodiment, by tilting the principal point surface from the state shown by the broken line parallel to the imaging surface to the state shown by the solid line, the extension line of the principal point surface becomes the intersection of the extension line of the imaging surface and the focus surface. Let them intersect. At this time, the tilt angle φ1 of the principal point surface is equal to the included angle (φ1) around the intersection of the extension line of the imaging surface and the extension line of the principal point surface.

The tilt angle φ1 can be calculated by the above-mentioned formula 3.

In the present embodiment, Hc is the distance from the floor surface to the center of the image pickup surface of the image pickup device 130 (camera height).

The controller 180 tilts the optical system 110 by the optical system tilting unit 300 so that the tilt angle of the principal point surface becomes φ1 (S18A). As a result, as shown in FIG. 15, the focusing surface becomes parallel to the floor surface. In addition, the upper edge and the lower edge of the depth of field range are parallel to the focus surface and the floor surface (state that can be regarded as parallel).

Here, in order to realize the depth of field set on the tilt shooting setting screen when the focus surface is raised to the position of the focus surface height H as described above, the aperture value F of the aperture 113 is opened. May have to be set to a higher value. The method of calculating the aperture value F for realizing the depth of field set on the tilt shooting setting screen will be described below. The timing at which the diaphragm 113 is driven so as to obtain the calculated diaphragm value F is, for example, after the execution of step S18.

FIG. 16 is a diagram illustrating a method of calculating the aperture value F that realizes the depth of field (D2) set on the tilt shooting setting screen.

The aperture value F can be calculated by the above-mentioned formula 4.

Here, Hc is the distance (camera height) from the floor surface to the center of the image pickup surface of the image pickup device 130.

2-3. Effects, etc. As described above, the digital camera 100A according to the present embodiment includes the image sensor 130 that captures a subject image formed on the image capturing surface to generate image data, and the focus lens 112. Optical system 110 for forming an image, a focus lens driving unit 122 for driving the focus lens 112 in the optical axis direction, and an optical system for tilting by rotating the principal point plane of the optical system 110 about an axis that is not parallel to the optical axis. The tilting unit 300 and a controller 180 that controls the focus lens driving unit 122 and the optical system tilting unit 300 are provided. The controller 180 causes (a) the focus lens drive unit 122 to move the focus lens 112 so as to focus on the first predetermined position P1 on the floor surface (an example of a reference plane) of the subject, and then (b) the optical axis. The focus position is moved from the first predetermined position P1 to the second predetermined position P2 based on the positional relationship between the second predetermined position P2 and the first predetermined position P1 at which the height from the floor surface becomes the predetermined height. Then, the focus lens 112 is moved to the focus lens driving unit 122, and thereafter, (c) the optical system tilting unit 300 is set so that the focus surface becomes a plane parallel to the floor surface and at a position of a predetermined height. The principal point surface of the optical system 110 is tilted.

According to the digital camera 100 of the present embodiment having such a configuration, it is possible to perform tilt photographing effectively using both the front side portion and the rear side portion of the depth of field. Therefore, it is possible to obtain an image in which the subject on the floor is in focus while suppressing an increase in ISO sensitivity.

In the present embodiment, before executing (a), the controller 180 causes the optical system tilting unit 300 to perform optical control so that the focusing surface is a plane that is perpendicular to the floor surface and includes the first predetermined position P1. The principal point surface of the system 110 is tilted.

As a result, the depth of field in the direction parallel to the floor centering on the first predetermined position P1 is the smallest. Therefore, in (a), when the focus lens 112 is moved to the focus lens driving unit 122 to focus on the first predetermined position P1, it is possible to improve the accuracy of focusing on the first predetermined position P1.

(Other embodiments)
As described above, the first embodiment has been described as an example of the technique disclosed in the present application. However, the technique in the present disclosure is not limited to this, and is also applicable to the embodiment in which changes, replacements, additions, omissions, etc. are appropriately made. Further, it is also possible to combine the constituent elements described in the first embodiment to form a new embodiment. Therefore, other embodiments will be exemplified below.

(1) In the first embodiment, the configuration for tilting the image sensor 130 has been described, and in the second embodiment, the configuration for tilting the optical system 110 has been described. However, both the image sensor 130 and the optical system 110 may be tilted.

(2) In the above embodiment, the tilt shooting setting screen is configured to allow the user to input the camera height, the camera depression angle, the focus surface height, and the depth of field using the touch sensor function of the liquid crystal monitor 220. did. However, the imaging device may be provided with a camera height sensor that detects the height of the camera from the ground, and the controller may automatically set the camera height based on the detected camera height. Further, the image pickup device may be provided with a camera depression angle sensor for detecting the camera depression angle, and the controller may automatically set the camera depression angle based on the detected camera depression angle. In addition, in the usage mode in which the lower end of the depth of field matches the floor surface, the controller calculates the focus surface height based on the set depth of field, and the focus surface height obtained by the calculation is automatically calculated. You may make it set with.

(3) In the above embodiment, the contrast AF is used as the autofocus method, but the phase difference AF or the image plane phase difference AF may be used.

(4) In the above embodiments, the lens-integrated camera has been described, but the present disclosure is also applicable to a lens-interchangeable camera. In the case of a lens-interchangeable camera, information on the focal length of the optical system can be obtained by the camera body communicating with the interchangeable lens.

(5) In the above embodiment, the case where the reference plane is the floor surface of the stadium has been described. However, the reference plane may be any plane, not a horizontal plane such as a floor. In this case, the height from the reference plane is the distance in the direction perpendicular to the reference plane.

(6) In the above embodiment, a digital camera was described as an example of the image pickup device, but the image pickup device is not limited to this. The idea of the present disclosure can be applied to various imaging devices such as digital video cameras, smartphones, and wearable cameras that can capture moving images.

(7) In the above-described first embodiment, the image pickup device tilting unit 160 sets the image pickup surface (sensor surface) of the image pickup device 130 to the x-axis (the axis that is perpendicular to the optical axis and is on the image pickup surface (the axis that is not parallel to the optical axis). One example)) is rotated and tilted. However, in the present disclosure, the axis of rotation need not be perpendicular to the optical axis, but may be in a direction that intersects the optical axis. That is, the axis of rotation need not be parallel to the optical axis.

(8) In Embodiment 2 described above, the optical system tilting unit 300 causes the principal point plane of the optical system 110 to be the x-axis (an axis that is perpendicular to the optical axis and is on the imaging surface (an example that is not parallel to the optical axis)). Rotate around and tilt. However, in the present disclosure, the axis of rotation does not have to be perpendicular to the optical axis and may be in a direction that intersects the optical axis. That is, the axis of rotation need not be parallel to the optical axis.

(9) In the above-described first embodiment, an example in which the processes of steps S12 and S13 are performed has been described, but the processes of steps S12 and S13 are not essential in the present disclosure. Further, in steps S12 and S13, it is only necessary to tilt the image pickup surface so that the angle of the focus surface approaches perpendicular to the floor surface as compared with the case where the image pickup surface is not tilted (the focus surface is relative to the floor surface). It doesn't have to be vertical). Even in this case, the effect of narrowing the depth of field in the direction horizontal to the floor surface can be obtained.

(10) In the above second embodiment, an example in which the processes of steps S12A and S13A are performed has been described, but the processes of steps S12A and S13A are not essential in the present disclosure. Further, in steps S12A and S13A, the main point surface may be tilted so that the angle of the focus surface approaches the angle perpendicular to the floor surface as compared to when the main point surface is not tilted (the focus surface is the floor surface. It does not have to be perpendicular to). Even in this case, the effect of narrowing the depth of field in the direction horizontal to the floor surface can be obtained.

As described above, the embodiments have been described as examples of the technology according to the present disclosure. To that end, the accompanying drawings and detailed description are provided. Therefore, among the components described in the accompanying drawings and the detailed description, not only the components essential for solving the problem but also the components not essential for solving the problem in order to exemplify the above technology Can also be included. Therefore, it should not be immediately recognized that these non-essential components are essential, even if those non-essential components are described in the accompanying drawings or the detailed description. Further, since the above-described embodiment is for exemplifying the technique in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or the scope of equivalents thereof.

The present disclosure can be widely used in an imaging device that captures a still image or a moving image.

100, 100A Digital camera 110 Optical system 110A Lens 110B Lens barrel 111 Zoom lens 112 Focus lens 113 Aperture 121 Zoom lens drive unit 122 Focus lens drive unit 123 Aperture drive unit 130 Image sensor
140 ADC
150 TG
160 Image sensor tilting unit 161, 162 Fixed frame 163 Movable plate 164, 165, 166, 167 Magnet 168, 169 Coil 170 Tilt angle sensor 180 Controller 190 Card slot 200 Memory card 210 Release button 220 Liquid crystal monitor 230 Built-in memory 300 Optical system tilting Part 310 Storage Frame 311 Holding Shaft 320 Actuator 321 Piston 350 Tilt Angle Sensor

Claims (6)

An image sensor that captures a subject image formed on the imaging surface to generate image data,
An optical system including a focus lens, which forms the subject image on the imaging surface;
A focus lens drive unit for moving the focus lens in the optical axis direction,
An image pickup device tilting unit that rotates and tilts the image pickup surface of the image pickup device about an axis that is not parallel to an optical axis,
A control unit that controls the focus lens drive unit and the image sensor tilting unit,
The control unit is
(A) Move the focus lens to the focus lens drive unit so as to focus on a first predetermined position on the reference plane of the subject, and then,
(B) Based on the positional relationship between the second predetermined position where the height from the reference plane is a predetermined height on the optical axis and the first predetermined position, the focus position is changed from the first predetermined position to the second predetermined position. Moving the focus lens to the focus lens drive unit so as to move to a position, and
(C) The image pickup element tilting unit tilts the image pickup surface of the image pickup element so that the focus plane is a plane parallel to the reference plane and at the position of the predetermined height.
Imaging device. The control unit, before executing the (a),
Tilting the image pickup surface of the image pickup device by the image pickup device tilting unit so that a focus plane is a plane that is perpendicular to the reference plane and includes the first predetermined position.
The image pickup apparatus according to claim 1. An image sensor that captures a subject image formed on the imaging surface to generate image data,
An optical system including a focus lens, which forms the subject image on the imaging surface;
A focus lens drive unit for moving the focus lens in the optical axis direction,
An optical system tilting unit that tilts by rotating a principal point surface of the optical system about an axis that is not parallel to the optical axis,
A control unit that controls the focus lens driving unit and the optical system tilting unit,
The control unit is
(A) Move the focus lens to the focus lens drive unit so as to focus on a first predetermined position on the reference plane of the subject, and then,
(B) Based on the positional relationship between the second predetermined position where the height from the reference plane is a predetermined height on the optical axis and the first predetermined position, the focus position is changed from the first predetermined position to the second predetermined position. Moving the focus lens to the focus lens drive unit so as to move to a position, and
(C) The optical system tilting portion tilts the principal point surface of the optical system such that the focusing surface is a plane parallel to the reference plane and at the predetermined height.
Imaging device. The control unit, before executing the (a),
Tilting the principal point surface of the optical system by the optical system tilting portion such that a focusing surface is a plane that is perpendicular to the reference plane and includes the first predetermined position.
The image pickup apparatus according to claim 3. Further comprising an operation unit that receives an input of the predetermined height,
The image pickup apparatus according to claim 1. A second operation unit that receives an input of a desired depth of field,
The image pickup apparatus according to claim 1.

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