JP2004040740A - Manual focus equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform focus adjustment in reference to a focus status displayed based on misalignment of images picked up while moving a diaphragm in a direction perpendicular to an optical axis. <P>SOLUTION: An aperture diaphragm is provided, which can be shifted right and left on an object light path. An extent of out-of-focus is obtained by detecting misalignment between the image picked up when the aperture diaphragm is shifted right, and that picked up when it is shifted left. A split image is created based on the image picked up when the aperture diaphragm is shifted right and the image picked up when the aperture diaphragm is shifted left, and displayed on a monitor. An operation quantity of a focus ring is detected by a ring sensor 7a, a motion quantity of the split image is calculated based on the extent of out-of-focus, the operation quantity of the focus ring, and the split image moving relative to the focusing operation is displayed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manual focus apparatus capable of performing a focus operation while observing a split image or a double image.
[0002]
[Prior art]
A distance meter-linked camera in which a double image coincidence type or vertical image coincidence type distance meter is incorporated in a finder is widely known. In the distance meter-linked camera, a change in the focus state due to the focus operation is observed as a change in the subject image shift, and high-precision focus can be achieved by visual observation. In the double image coincidence type finder, a double image by a finder image and a distance meter image is observed in the field of view of the finder. To focus, the distance meter image that moves in conjunction with the focus operation matches the viewfinder image. The vertical image coincidence type finder forms an upper and lower divided image of a subject in a part of the finder field 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 a focused state.
[0003]
Further, as described in JP-A-9-214813, JP-A-2001-309210, etc., instead of incorporating a distance meter that optically forms a double image or a split image, A finder using an electronic image for focus adjustment is known. These viewfinders move and display subject images that are displayed differently according to the size of the focus shift in conjunction with the focus operation, reducing the number of optical components and enabling space saving and cost reduction. Yes.
[0004]
In order to perform the moving display of the image interlocked with the focusing and the matching display of the image at the time of focusing, it is necessary to obtain the size of the focus shift in advance. Conventionally, a triangulation method that calculates a focus shift from a subject distance measured using infrared rays, or photographic light captured on an optical path symmetric with respect to the photographic optical axis is received by two line sensors, and the photoelectric signal A phase difference detection method for calculating a focus shift from the phase difference is generally used.
[0005]
[Problems to be solved by the invention]
However, when calculating the size of the focus shift by the triangulation method, in addition to the image sensor, electrical components that require high built-in accuracy such as a light projection element and a position detection element for active distance measurement are provided. There is a problem that the manufacturing cost increases. Similarly, the conventional phase difference detection method has a problem in that the manufacturing cost increases because an optical system, a line sensor, and the like that separate the photographing light are separately provided.
[0006]
The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a manual focus device capable of displaying a focus state using an image signal obtained from an image sensor and capable of performing manual manual focusing. To do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the manual focus device of the present invention moves the aperture stop provided on the subject optical path perpendicularly to the optical axis, and captures the subject light that is displaced due to the parallax of the stop when the subject is out of focus. Both images are displayed. The magnitude of the subject light deviation generated on the imaging surface changes in accordance with the focus deviation, and no subject light deviation occurs in a focused state where there is no focus deviation. By utilizing this, the subject light imaged at two points on the moving path of the aperture stop is simultaneously displayed and output so that the degree of focus deviation can be determined by comparing the degree of deviation 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 stop is moved, and the focus state is displayed based on the focus shift. In order to know the focus state accurately by the display shift of the subject image, the number of display pixels that is comparable to the number of pixels to be captured is required. By obtaining the size of the focus shift, for example, the shift of the subject image can be supplemented. The image can be enlarged and displayed with high accuracy without increasing the number of display pixels.
[0009]
According to the third aspect of the present invention, a display equivalent to a conventional optical split image is displayed by an electronic image. When the focus is adjusted by a focus operation, a subject image given a display shift is displayed in a consistent manner. ing.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, a digital still camera 1 incorporating the present invention is provided with a lens barrel 3 holding an imaging lens 2, a grip portion 4, a release button 5, and a shooting mode switching dial 6. The release button 5 is configured so that it can be pressed in two stages, a half-press operation and a full-press operation. A focus ring 7 is provided on the outer periphery of the lens barrel 3, and focusing can be performed at the time of photographing by rotating the same.
[0011]
In FIG. 2, a back monitor 8 and a viewfinder 9 are provided on the back 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 operations of the back monitor 8 and the small monitor in the finder 9 are switched and controlled, and the back monitor 8 is forcibly turned off when the finder 9 is used. If the finder 9 is used, power consumption can be saved compared to when the back monitor 8 is used.
[0012]
In FIG. 3, the digital still camera 1 includes a main control unit 11, an imaging 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 imaging signal processing unit 12 performs amplification processing, image processing, and the like of the image signal output from the imaging unit 15. The display control unit 4 displays and outputs the subject image on the back monitor 8 and the small monitor of the finder 9. The image storage unit 14 stores the image signal output from the imaging 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 stop 18, and a CCD image pickup device 19. The zoom lens 16 is driven in the optical axis direction by a zoom lens driving unit 20 having a zoom motor, and optically zooms 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 an image of subject light on the CCD image pickup device 19 at a focus position corresponding to the subject distance. The focus ring 17 is provided with a ring sensor 7a for detecting the rotation operation amount. The iris drive unit 21 adjusts the aperture diameter of the aperture stop 18 and shifts the aperture stop 18 in a plane orthogonal to the optical axis.
[0014]
In FIG. 4, the aperture stop 18 includes two stop blades 25 and 26. Flat teeth 25a and 26a are formed below the diaphragm blades 25 and 26, respectively. The diaphragm blades 25 and 26 are driven by iris motors 27 and 28. On the drive shafts of the iris motors 27 and 28, there are provided small gears 29 and 30 that mesh with the spur tooth portions 25a and 26a. By driving the rack and pinion, each of the diaphragm blades 25 and 26 independently moves freely in the left-right direction, and the continuous aperture diameter adjustment of the aperture diaphragm 18 and the shift movement of the aperture diaphragm 18 are performed.
[0015]
In FIG. 5, the aperture stop 18 shifts between two distance measuring positions P1 and P2 that are symmetric with respect to the optical axis. As shown in FIG. 5 (a), when the focus lens 17 is in the position for focusing light from the object point O1 on the imaging plane P _I, consider when the aperture stop 18 is moved to the position P1. Principal ray R1 from the object point O1 reaches the imaging plane _{P I} at point S1 of the optical axis A1. Principal rays R2 object point O2 in the distance from the object point O1 intersects with the optical axis A1 in front of the image plane P _I, reaches the point S2 of the imaging plane P _I. The main ray R3 object point O3 near than the object point O1, without intersecting the optical axis A1, reaches the point S3 in the imaging plane P _I. When the aperture stop 18 is moved to the position P2, as shown in FIG. 5 (b), the principal rays R1, R2, R3 point on the imaging plane _{P I S1, S2 ', S3} ' reach, respectively, respectively the To do.
[0016]
In FIG. 6 (a), light from the object point O1 is imaged on the imaging surface P _I, illustrates this as focus. In FIG. 6 (b), shows how the light from the object point O2 is imaged before the imaging plane P _I as a front focus state. The image shift G2 in the front pin state is the distance between the point S2 and the point S2 ′. Further, as shown as a rear focus state in FIG. 6 (c), the light from the object point O3 is imaged behind the imaging plane P _I. If the image deviation G2 when in the front pin state is positive and the image deviation G3 when in the rear pin state is negative, the direction in which the focus lens 17 should be moved can be known.
[0017]
If the distance from the aperture stop 18 to the imaging surface P _I is sufficiently small as compared with the object distance, the aperture center at each position of the aperture stop 18, by the optical path of the principal ray to the imaging plane P _I, it approximates a similar relationship Two possible triangles are formed. And the shift amount of movement M of the reciprocating of the aperture stop 18, because the similarity ratio is calculated from the image shift amount G, the distance from the imaging plane P _I to the imaging surface in each object distance, i.e. the size of the focus deviation seen. If the magnitude of the focus shift 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 imaging signal processing unit 12 includes an image signal capturing circuit 33, an image processing circuit 34, a focus evaluation circuit 35, and a focus image output circuit 36. The image signal capturing 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 pickup device 19 is always constant, and complements the luminance of the image. The pixel mixing circuit 41 performs a process of adding the luminance of adjacent pixels in the image and replacing it with the luminance of one pixel, and lowers the resolution to correct 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 on the image signal based on each set gain of RGB, and performs white balance adjustment. The gamma correction circuit 43 corrects the contrast gamma of the image signal. The image signal subjected to 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 an image for two frames captured when the aperture stop 18 is moved. The focus shift calculation circuit 46 analyzes the two stored subject images and calculates a positional shift between the two images in units of pixels. The size of the focus shift is calculated from the size 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 composition circuit 47 and a display movement amount calculation circuit 48. The split image combining circuit 47 cuts out and combines the two frames of 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 amount of change in focus 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 on the monitor in the back monitor 8 and the finder 9. As shown in FIG. 8, on the monitor, the focus adjustment area 50 and the object scene display area 51 are displayed separated by the center and the periphery of the screen. In the field display area 51, a subject image captured when the aperture center of the aperture stop 18 is on the optical axis is displayed. In the focus adjustment area 50, a right-side 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 obtained by partially dividing the left-side image 53 at the time of right shifting, respectively. Is displayed.
[0023]
When the focus ring 7 is operated, rotation operation amount information detected by the ring sensor 7 a 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 composition circuit 47 changes the cut-out positions of the two-frame images stored in the shift image storage circuit 45 based on the calculated moving display amount, and displays a secondary split image obtained by synthesizing the two split images. 13 is output. Thereby, each time the focus ring 7 is operated, the upper divided image 52a and the lower divided image 53a in the focus adjustment area 50 are moved and displayed symmetrically. When the focus shift is reduced, the split image display shift is reduced, and the images are matched in focus. On the other hand, when the focus shift increases, the split image display shift increases.
[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 subject light is started, and an image signal for each frame is input to the image signal capturing circuit 33 at a constant imaging speed. In the image signal capturing circuit 33, image signal amplification processing or pixel mixing processing is performed for each frame, and the luminance of the image is corrected. 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 pressing the release button 5 halfway 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 rotation directions of the small gears 29 and 30 are the same. The aperture blades 25 and 26 move in the same direction, and the aperture stop 18 shifts.
[0026]
When the shift of the aperture stop 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-side image 53 is stored in the shift image storage circuit 45.
[0027]
Next, the iris driving unit 21 shifts the aperture stop 18 to the left. The aperture stop 18 moves to a position symmetrical to the optical axis with respect to the stop position during the 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-side image 52 is stored in the shift image storage circuit 45.
[0028]
The aperture stop 18 returns to the position on the optical axis, freeze display is ended on the monitor, and 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 to the focus shift calculation circuit 46. The focus shift calculation circuit 46 calculates the size of the image shift and calculates the focus shift from this image shift. The calculated out-of-focus amount is sent to the focus image output circuit 36 as out-of-focus information.
[0029]
In the split image composition circuit 47, a primary split image displayed in the focus adjustment area 50 is created. The primary split image is output to the display control unit 13, and a 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. The display movement amount calculation circuit 48 calculates the size of the display displacement based on the rotation operation amount information, and creates a secondary split image in which the size of the display displacement is changed. The secondary split image is output to the display control unit 13, and an image in which each divided image in the focus adjustment area 50 is moved symmetrically is displayed.
[0030]
When the focus ring 7 is operated, split image movement display processing is performed. When the focus lens 17 approaches the in-focus position, the split image display shift is reduced, and when the focus lens 17 reaches the in-focus position, the split image is split. The images match. 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 an image captured during the release operation is stored. When the image storage is completed, the focus adjustment area 50 disappears and the subject image is displayed on the monitor.
[0031]
In the above embodiment, the aperture stop is moved between two points that are symmetric with respect to the optical axis, and the focus area is set at the center of the screen. However, the focus area is displayed on the screen by biasing the left and right shift amount of the aperture stop. It can also be changed from the center in the left-right direction. Further, by configuring the aperture stop so as to be two-dimensionally movable left and right and up and down, the focus area can be set to an arbitrary area of the photographing range.
[0032]
In the above-described embodiment, the split image is created using the subject image captured when the aperture stop is moved. For example, a superimposed display of a reference still image and a moving image in which transparency is set is used. Thus, a double image coincidence type focus image may be displayed, and further, split image display and double image display may be switched.
[0033]
When more precise focusing is required, if the size of the focus shift is required, the focus status may be auxiliary displayed by re-displaying a split image with a large display shift. It's okay. For example, instead of the subject image, index images such as triangles and circles may be moved and displayed relative to the reference image to perform auxiliary display in focus. In the present invention, the in-focus state, the front pin state, the rear pin state, or whether the focus lens has approached or moved away from the focus position may be supplementarily notified. For example, a plurality of small light sources may be used to focus. A change in the state may be displayed by light emission.
[0034]
【The invention's effect】
As described above, the manual focus device of the present invention can simultaneously display and output the subject image captured when the aperture stop is moved, and can confirm the focus state from the size of the display shift. Unlike the distance method and the phase difference detection method, there is no need to provide a sensor or optical component other than the image sensor, and the focus state can be displayed while suppressing an increase in cost.
[0035]
Also, since the focus shift can be obtained from the size of the shift of the subject image picked up when the aperture is moved, the change of the focus shift can be calculated back from the focus operation amount, and a smooth moving display of the image linked to the focus operation can be performed. it can. It is also possible to display an auxiliary image for performing precise focusing based on the obtained focus shift size. Since it is not necessary to drive the aperture stop perpendicularly to the optical axis every time the focus state is changed, the number of times of driving the stop is reduced and power consumption can be saved.
[0036]
Furthermore, by performing display equivalent to that of a conventional optical split image, a highly accurate focus operation can be performed while checking the subject image.
[Brief description of the 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 the digital still camera.
FIG. 4 is a perspective view of an aperture stop.
FIG. 5 is an explanatory diagram of image misalignment caused by shift movement of the aperture stop.
FIG. 6 is an explanatory diagram showing the size of image shift that occurs in each focus state.
FIG. 7 is a circuit block diagram of an image signal processing unit.
FIG. 8 is an explanatory diagram showing image composition;
FIG. 9 is a flowchart showing a flow of operation of the digital camera.
[Explanation of symbols]
7 Focus ring 8 Back monitor 9 Viewfinder 15 Imaging unit 17 Focus lens 18 Aperture stop 19 CCD image pickup device 21 Iris driving unit 25, 26 Aperture blades 25a, 26a Spiral teeth 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 composition circuit 48 display movement amount calculation circuit 50 focus adjustment area

Claims (3)

In the manual focus device that moves the focus lens in the optical axis direction by the focus operation and forms the subject light on the image sensor,
A diaphragm moving means for moving the aperture stop on the subject optical path on a plane perpendicular to the optical axis;
Storage means for storing two subject images respectively captured at two ranging positions where the aperture stop moves;
A manual focus apparatus, comprising: a display means for combining and outputting the two subject images and displaying whether or not the focus state is appropriate. A process for comparing the two subject images read from the storage means to determine the size of the image shift, a process for calculating the focus shift from the image shift, and a focus lens alignment based on the focus shift. 2. The manual focus device according to claim 1, further comprising arithmetic means for performing processing for specifying a focal position. The display means displays a split image formed from the two subject images, and the split image is moved and displayed as the focus state changes, and when the focus lens reaches the in-focus position. 3. The manual focus device according to claim 1, wherein a match display is performed.

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