Manual focus equipment

【0001】

[Technical field to which the invention belongs]

The present invention relates to a manual focus device capable of performing a focus operation while observing a split image or a double image.

【0002】

[Conventional technology]

Distance meter interlocking cameras with a built-in double image matching type or vertical image matching type rangefinder in the viewfinder are widely known. In the rangefinder-linked camera, the change in the focus state due to the focus operation is observed as the change in the deviation of the subject image, and highly accurate focusing by visual inspection is possible. In the double image matching type finder, a double image of the finder image and the rangefinder image is observed in the field of view of the finder. To focus, the rangefinder image that moves in conjunction with the focus operation is matched with the finder image. The vertical image matching type finder forms a vertical split image of a subject in a part of the finder field of view by a micro split image prism in the finder optical path. Each of the vertically divided images moves symmetrically in conjunction with the focus operation, and the divided images match in the focused state.

【0003】

Further, as described in JP-A-9-214813, JP-A-2001-309210, etc., instead of incorporating a range finder that optically forms a double image or a split image, the captured subject A finder that uses an electronic image for focus adjustment is known. In these finder, the subject images that are displayed differently according to the size of the out-of-focus are moved and displayed in conjunction with the focus operation, reducing the number of optical components and enabling space saving and cost reduction. There is.

【0004】

In order to display the movement of the image linked to the focusing and the matching display of the image at the time of focusing, it is necessary to determine the size of the out-of-focus in advance. Conventionally, a triangular ranging method that calculates the focus shift from the subject distance measured using infrared rays, or a shooting light captured on an optical path symmetrical to the shooting optical axis is received by two line sensors, and the photoelectric signal is received. A phase difference detection method that calculates the focus shift from the phase difference of the above is common.

【0005】

[Problems to be Solved by the Invention]

However, when calculating the amount of focus shift by the triangular distance measurement method, in addition to the image sensor, electrical components such as a light projecting element for active distance measurement and a position detection element that require high built-in accuracy are provided. There is a problem that the manufacturing cost rises. Similarly, the conventional phase difference detection method has a problem that the manufacturing cost increases because an optical system for splitting the photographed light, a line sensor, and the like are separately provided.

【0006】

An object of the present invention is to provide a manual focus device capable of displaying a focus state by using an image signal obtained from an image sensor and capable of good manual focusing in consideration of the above problems. To do.

【0007】

[Means for solving problems]

In order to achieve the above object, the manual focus device of the present invention moves the aperture diaphragm provided on the subject optical path perpendicular to the optical axis, and captures the subject light that is out of focus due to the parallax of the diaphragm. However, both images are displayed. The magnitude of the deviation of the subject light that occurs on the imaging surface changes according to the magnitude of the out-of-focus, and the subject light does not deviate in the focused state without the out-of-focus. Utilizing this, the subject light captured at two points on the moving path of the aperture diaphragm is displayed and output at the same time, and the degree of out-of-focus can be determined by comparing the degree of out-of-focus between the two images.

【0008】

According to the second aspect of the present invention, the focus shift is calculated from the shift of the subject image captured when the aperture diaphragm is moved, and the focus state is displayed based on the shift shift. In order to accurately know the focus state by the display shift of the subject image, the number of display pixels equivalent to the number of captured pixels is required, but by obtaining the size of the focus shift, for example, the shift of the subject image is assisted. It can be enlarged and displayed, and highly accurate focusing can be performed without increasing the number of display pixels.

【0009】

The invention according to claim 3 displays an electronic image equivalent to a conventional optical split image, and when focusing is performed by a focus operation, a subject image with a display shift is displayed in a matching manner. ing.

【0010】

BEST MODE FOR CARRYING OUT THE INVENTION

In FIG. 1, the digital still camera 1 incorporating the present invention is provided with a lens barrel 3 holding an image pickup lens 2, a grip portion 4, a release button 5, and a shooting mode switching dial 6. The release button 5 is configured to enable a two-step pressing operation of a half-pressing operation and a full-pressing operation. A focus ring 7 is provided on the outer circumference of the lens barrel 3, and focusing can be achieved during shooting by rotating the focus ring 7.

【0011】

In FIG. 2, a back monitor 8 and a finder 9 are provided on the back surface of the digital still camera 1. The back monitor 8 is composed of a liquid crystal display panel capable of displaying a subject image in full color. In addition, a small color liquid crystal monitor is provided inside the finder 9. The operation of the back monitor 8 and the small monitor in the finder 9 is switched and controlled, and the back monitor 8 is forcibly turned off when the finder 9 is used. By using Finder 9, you can save power consumption compared to when using Back Monitor 8.

【0012】

In FIG. 3, the digital still camera 1 is provided with a main control unit 11, an image pickup signal processing unit 12, a display control unit 13, and an image storage unit 14. The main control unit 11 outputs a control signal to each unit according to a pre-programmed operation sequence, and manages the electrical operation of the entire camera. The image pickup signal processing unit 12 performs amplification processing, image processing, and the like of the image signal output from the image pickup unit 15. The display control unit 4 displays and outputs a subject image on a small monitor of the back monitor 8 or the finder 9. The image storage unit 14 stores the image signal output from the image pickup signal processing unit 12 as image data when the release button 5 is fully pressed.

【0013】

The image pickup unit 15 includes a zoom lens 16, a focus lens 17, an aperture diaphragm 18, and a CCD image sensor 19. The zoom lens 16 is driven in the optical axis direction by a zoom lens driving unit 20 provided with a zoom motor, and optically changes the magnification of the subject image formed on the CCD image sensor 19. The focus lens 17 moves in the optical axis direction in accordance with the operation of the focus ring 7, and forms a subject light on the CCD image sensor 19 at a focusing position according to the subject distance. The focus ring 17 is provided with a ring sensor 7a that detects the amount of rotation operation. The iris drive unit 21 adjusts the aperture diameter of the aperture diaphragm 18 and shifts the aperture diaphragm 18 in a plane orthogonal to the optical axis.

【0014】

In FIG. 4, the aperture diaphragm 18 is composed of two diaphragm blades 25 and 26. Flat tooth portions 25a and 26a are formed below the diaphragm blades 25 and 26. The diaphragm blades 25 and 26 are driven by the iris motors 27 and 28. On the drive shafts of the iris motors 27 and 28, small gears 29 and 30 that mesh with the spur teeth 25a and 26a are provided. By driving this rack and pinion, each of the diaphragm blades 25 and 26 independently and freely moves in the left-right direction, and continuous adjustment of the aperture diameter of the aperture diaphragm 18 and shift movement of the aperture diaphragm 18 are performed.

【0015】

In FIG. 5, the aperture diaphragm 18 shifts between two optical axis symmetric ranging positions P1 and P2. As shown in FIG. 5 (a), the focus lens 17 captures the light from the object point O1 on the imaging surface P._IConsider the case where the aperture stop 18 moves to the position P1 when the image is formed in. The main ray R1 from the object point O1 is the imaging surface P at the point S1 on the optical axis A1._ITo reach. The main ray R2 of the object point O2, which is farther than the object point O1, is the image plane P._ICrosses the optical axis A1 in front of, and the imaging surface P_IReach the upper point S2. In addition, the main ray R3 of the object point O3, which is closer than the object point O1, does not intersect the optical axis A1 and is the imaging surface P._IReach the upper point S3. When the aperture stop 18 moves to position P2, the main rays R1, R2, and R3 are the image plane P, as shown in FIG. 5 (b)._IReach the upper points S1, S2', S3', respectively.

【0016】

In FIG. 6 (a), the light from the object point O1 is the imaging surface P._IThe image is formed above, and this is shown as the in-focus state. In Fig. 6 (b), the light from the object point O2 is the imaging surface P._IThe state of forming an image in front of is shown as the front pin state. The image shift G2 in the front pin state is the distance between the point S2 and the point S2'. In addition, as shown in Fig. 6 (c) as the rear pin state, the light from the object point O3 is the imaging surface P._IImage is formed behind. If the image shift G2 in the front pin state is set to positive and the image shift G3 in the rear pin state is set to negative, the direction in which the focus lens 17 should be moved can be known.

【0017】

Imaging surface P from aperture diaphragm 18_IIf the distance to is sufficiently smaller than the subject distance, the center of the aperture at each position of the aperture stop 18 and the imaging surface P_IThe optical paths of the main rays up to, form two triangles that can be approximated by similar relationships. Since the similarity ratio can be obtained from the reciprocating shift movement amount M of the aperture diaphragm 18 and the image deviation amount G, the imaging surface P_IFrom the above, the distance to the image plane at each subject distance, that is, the magnitude of the out-of-focus can be known. If the magnitude of the out-of-focus is known, the distance from the current position of the focus lens 17 to the in-focus position can be obtained.

【0018】

In FIG. 7, the image pickup signal processing unit 12 includes an image signal acquisition circuit 33, an image processing circuit 34, a focus evaluation circuit 35, and a focus image output circuit 36. The image signal acquisition circuit 33 is provided with an auto gain controller 40 and a pixel mixing circuit 41. The auto gain controller 40 performs amplification processing while adjusting the gain so that the average level of the output signal of the CCD image sensor 19 is always constant, and complements the brightness of the image. The pixel mixing circuit 41 performs a process of adding the brightness of adjacent pixels in the image and replacing it as the brightness of one pixel, lowering the resolution and correcting the contrast of the image. One of the auto gain controller 40 and the pixel mixing circuit 41 operates according to the set state.

【0019】

The image processing circuit 34 is provided with a white balance circuit 42, a gamma correction circuit 43, and an AD converter 44. The white balance circuit 42 performs amplification processing based on each RGB set gain on the image signal, and adjusts the white balance. The gamma correction circuit 43 corrects the contrast gamma of the image signal. The image signal after each processing is digitally converted by the AD converter 44.

【0020】

The focus evaluation circuit 35 is provided with a shift image storage circuit 45 and a focus shift calculation circuit 46. The shift image storage circuit 45 stores two frames of images captured when the aperture diaphragm 18 is moved. The focus shift calculation circuit 46 analyzes the two stored subject images and determines the positional shift between the two images on a pixel-by-pixel basis. The magnitude of the focus shift is calculated from the magnitude of the image shift, and the focus shift information is output to the focus image output circuit 36.

【0021】

The focus image output circuit 36 is provided with a split image synthesis circuit 47 and a display movement amount calculation circuit 48. The split image compositing circuit 47 cuts out and synthesizes the two-frame images read from the shift image storage circuit 45, and converts them into a split image for displaying the focus state. The display movement amount calculation circuit 48 converts the change in focus shift due to the operation of the focus ring 7 into the display movement amount of the split image.

【0022】

The display control unit 13 displays and outputs the output image from the image processing circuit 34 and the split image output from the focus image output circuit 36 to the monitor in the back monitor 8 or the finder 9. As shown in FIG. 8, on the monitor, the focus adjustment area 50 and the field area display area 51 are displayed separated by the center and the periphery of the screen. In the field area display area 51, a subject image captured when the aperture center of the aperture diaphragm 18 is on the optical axis is displayed. In the focus adjustment area 50, a right-sided image 52 taken when the aperture stop 18 is shifted to the left, and an upper-divided image 52a and a lower-divided image 53a in which a part of the left-sided image 53 at the time of right-shifting is vertically divided, respectively. Is displayed.

【0023】

When the focus ring 7 is operated, the rotation operation amount information detected by the ring sensor 7a is input to the display movement amount calculation circuit 48 via the main control unit 11. The display movement amount calculation circuit 48 calculates the display movement amount of the split image based on the rotation speed information. The split image compositing circuit 47 changes the cropping position of the two-frame image stored in the shift image storage circuit 45 based on the calculated movement display amount, and displays the secondary split image obtained by compositing these. Output to 13. As a result, each time the focus ring 7 is operated, the upper split image 52a and the lower split image 53a in the focus adjustment area 50 are symmetrically moved and displayed. When the focus shift becomes smaller, the display shift of the split image becomes smaller, and the image matches in the focused state. On the other hand, when the focus shift becomes large, the display shift of the split image becomes large.

【0024】

Next, the operation of the present invention will be described with reference to FIG. When the CCD image sensor 19 is driven, imaging of the subject light is started, and the image signal for each frame is input to the image signal acquisition circuit 33 at a constant imaging speed. In the image signal acquisition circuit 33, the image signal amplification process or the pixel mixing process is performed for each frame to correct the brightness of the image. The image signal is output to the display control unit 13, and the captured subject image of each frame is continuously displayed on the monitor.

【0025】

After the imaging is started, the focus shift measurement is started by half-pressing the release button 5 or finely operating the focus ring 7. A shift drive start signal is sent from the main control unit 11 to the iris drive unit 21, and the iris drive unit 21 drives the iris motors 27 and 28 so that the small gears 29 and 30 rotate in the same direction. The diaphragm blades 25 and 26 move in the same direction, and the aperture diaphragm 18 shifts.

【0026】

When the shift of the aperture diaphragm 18 is started, the display control unit 13 freezes and displays the subject image on the monitor. The iris drive unit 21 first shifts the aperture stop 18 to the right. When the aperture stop 18 moves a certain distance, the right shift stops. At this time, the image signal output from the CCD image sensor 19 is input to the focus evaluation circuit 35, and the left-sided image 53 is stored in the shift image storage circuit 45.

【0027】

Next, the iris drive unit 21 shifts the aperture stop 18 to the left. The aperture stop 18 moves to a position symmetrical with the optical axis at the stop position at the time of right shift. When the right shift is completed, the image signal output from the CCD image sensor 19 is input to the focus evaluation circuit 35, and the right-sided image 52 is stored in the shift image storage circuit 45.

【0028】

The aperture diaphragm 18 returns to the position on the optical axis, the freeze display ends on the monitor, and the display of the subject is resumed. In the focus evaluation circuit 35, the image data for two frames stored in the shift image storage circuit 45 is read out to the focus shift calculation circuit 46. The focus shift calculation circuit 46 determines the magnitude of the image shift, and calculates the magnitude of the focus shift from this image shift. The calculated magnitude of the out-of-focus is sent to the focus image output circuit 36 as the out-of-focus information.

【0029】

The split image compositing circuit 47 creates a primary split image to be displayed in the focus adjustment area 50. The primary split image is output to the display control unit 13, and the focus adjustment area 50 appears on the monitor. When the focus ring 7 is operated, the rotation operation amount information is input to the display movement amount calculation circuit 48. In the display movement amount calculation circuit 48, the magnitude of the display deviation is calculated based on the rotation operation amount information, and a secondary split image in which the magnitude of the display deviation is changed is created. The secondary split image is output to the display control unit 13, and an image in which each split image in the focus adjustment area 50 is moved symmetrically is displayed.

【0030】

Every time the focus ring 7 is operated, the split image is moved and displayed. When the focus lens 17 approaches the in-focus position, the split image display shift becomes smaller, and when the focus lens 17 reaches the in-focus position, the split image is split. The image matches. When the release button 5 is fully pressed, a release operation signal is sent to the main control unit 11. The image signal output from the image processing circuit 34 is sent to the image storage unit 14, and the image captured during the release operation is saved. When the image is saved, the focus adjustment area 50 disappears and the subject image is displayed on the monitor.

【0031】

In the above embodiment, the aperture diaphragm is moved between two points symmetrical about the optical axis to set the focus area at the center of the screen. However, the focus area is set to the screen by biasing the left and right shift movement amounts of the aperture diaphragm. It can also be changed from the center to the left and right. Further, by configuring the aperture diaphragm so that it can be moved two-dimensionally from side to side and up and down, the focus area can be set to an arbitrary area of the shooting range.

【0032】

Further, in the above embodiment, the split image is created by using the subject image taken when the aperture diaphragm is moved. For example, the reference still image and the moving image with the transparency set are superimposed and displayed. The focus image of the double image matching type may be displayed, and the split image display and the double image display may be switched.

【0033】

When more precise focusing is required, if the size of the out-of-focus is required, the focus state may be auxiliary-displayed by redisplaying the split image with a large display-out, and the form of this auxiliary display is arbitrary. It's fine. For example, instead of the subject image, an index image such as a triangle or a circle may be moved and displayed relative to the reference image to perform an auxiliary display of the focus state. Further, in the present invention, the in-focus state, the front-focus state, the back-focus state, or whether the focus lens approaches or deviates from the in-focus position may be supplementarily notified. For example, a plurality of small light sources may be used to focus. The change in state may be displayed by light emission.

【0034】

[Effect of the invention]

As described above, in the manual focus device of the present invention, the subject image captured when the aperture diaphragm is moved can be displayed and output at the same time, and the focus state can be confirmed from the magnitude of the display deviation. Unlike the distance method and the phase difference detection method, it is not necessary to provide a sensor or optical component other than the image sensor, and it is possible to display the focus state while suppressing an increase in cost.

【0035】

In addition, since the focus shift can be obtained from the magnitude of the shift of the subject image captured when the aperture is moved, the change in the focus shift can be calculated back from the focus operation amount, and the smooth movement display of the image linked to the focus operation can be performed. it can. It is also possible to display an auxiliary image for fine focusing based on the obtained size of the out-of-focus. Since it is not necessary to drive the aperture diaphragm perpendicular to the optical axis each time the focus state is changed, the number of times the diaphragm is driven is reduced and power consumption can be saved.

【0036】

Further, by displaying the same as the conventional optical split image, it is possible to perform a highly accurate focus operation while checking the subject image.

[Simple explanation of drawings]

FIG. 1 is a front perspective view of a digital still camera incorporating the present invention.

FIG. 2 is a rear perspective view of a digital still camera incorporating the present invention.

FIG. 3 is a block diagram showing an electrical configuration of a digital still camera.

FIG. 4 is a perspective view of an aperture diaphragm.

FIG. 5 is an explanatory diagram of an image shift caused by a shift movement of an aperture diaphragm.

FIG. 6 is an explanatory diagram showing the magnitude of image deviation that occurs in each focused state.

FIG. 7 is a circuit block diagram of an image signal processing unit.

FIG. 8 is an explanatory diagram showing a composition of images.

FIG. 9 is a flowchart showing an operation flow of a digital camera.

[Explanation of symbols]

7 Focus ring 8 Back monitor 9 Finder 15 Imaging unit 17 Focus lens 18 Aperture aperture 19 CCD image sensor 21 Iris drive unit 25,26 Aperture blade 25a, 26a Spur blade 27,28 Iris motor 29,30 Small gear 35 Focus evaluation circuit 36 Focus image output circuit 45 Shift image storage circuit 46 Focus shift calculation circuit 47 Split image synthesis circuit 48 Display movement amount calculation circuit 50 Focus adjustment area