JP3630965B2 - Focus detection apparatus, camera, and focus detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention Has a function of executing a focus detection operation for each of a plurality of focus detection areas Focus detection device , camera And focus detection method It is about.
[0002]
[Prior art]
With conventional cameras that can perform multi-point distance measurement, it is often the case that the closest "nearest" distance measurement area is selected from among multiple distance measurement results, so there are many cases of erroneous distance measurement. For example, if the result of three-point distance measurement has a specific pattern such as far, middle, and near, select a middle distance metering point (since “near” may be the ground, etc.) An algorithm having such an algorithm has been proposed (Japanese Patent Laid-Open No. 2-282234).
[0003]
In addition, the applicant of the present application proposes a device that has a number of distance measuring points in the shooting screen, can measure the distances of these distance measuring points, and can measure the distance (defocus amount) in any direction in the shooting space. (Japanese Patent Publication No. 4-67607).
[0004]
This proposed apparatus will be described by taking as an example the case of shooting a scene as shown in FIG.
[0005]
First, the shooting screen is finely divided into blocks (with a plurality of pixels on the area sensor as a set), and distance distribution information (distance map) as shown in FIG. 7 is obtained. Then, in order to determine the object arrangement in the object space, grouping of each object constituting the space is performed.
[0006]
FIG. 8 is an example of a result of grouping based on the distance map data in FIG. 7, and the area is divided for each object by grouping. As a practical grouping technique, several methods are generally known. The simplest example is that if the difference in distance (or defocus) between two adjacent blocks is less than or equal to a predetermined value, the determination that the two blocks form the same object is made for all adjacent blocks. It is a method of applying.
[0007]
By the above method, the screen is divided into areas (grouping) for each object constituting the imaging space as shown in FIG.
[0008]
Then, for example, the area of the main subject is determined from the objects constituting the shooting space using distance information, object size information, position information on the screen, and the degree of inclination of the object. Is.
[0009]
As a method of grouping, there is a method of creating a histogram from a distance map and grouping based on the histogram distribution. Further, in the method of focusing, attention is paid only to the closest distance and the most frequent distance, and when the difference between the two is small, the focus is adjusted to the middle, and otherwise, the previous subject is focused (Japanese Patent Laid-Open No. 62-255911). ) Etc.
[0010]
[Problems to be solved by the invention]
However, in actual focus adjustment, focus detection cannot always be performed correctly at all distance measuring points (focus detection points), and a distance map is created by distance measurement errors and subtle movements of the photographer and subject during focus adjustment. It will change. Further, in a focus detection system that performs focus detection using a light beam that passes through the photographic lens, the influence of the stop position of the photographic lens when performing focus detection is large. In particular, if a distance map is repeatedly created while performing focus adjustment, the distance map is slightly different each time it is re-created. As shown in FIG. 6, there is no problem when the subjects are separated from each other. However, when the subjects are close to each other or the distance between the background and the main subject is short, the problem becomes significant.
[0011]
FIG. 9A shows an example of such a scene, in which two people are standing in front of a wall side by side. FIG. 4B shows a focus detection area or a distance measurement area of focus detection means for adjusting the focus of this scene. Various examples of creating a defocus map using such a focus detection system are shown in FIGS.
[0012]
FIG. 10A shows an example of division into four regions. Areas a1 and a2 are almost left It becomes the area of the person on the side, area a3, a4 right It corresponds to the part of the person on the side. In this case, the background wall portion is hardly recognized as a region because the focus was hardly detected (in the figure, it is blank).
[0013]
FIG. 10B shows an example in which a person is correctly divided into areas b1 and b2. Further, in FIG. 10C, two persons are included in one area (area c3 ) And part of the wall and part of the person are divided into different areas (see areas c1 and c2). In FIG. 10D, two persons and a part of the wall are classified into the same area (area d2), and only a part of the person is recognized as another area (area d1).
[0014]
In this way, even when shooting the same scene, the distance map is considerably different depending on the position of the shooting lens and the possibility of focus detection.
[0015]
When focus adjustment is performed by repeatedly determining focus points according to different distance maps in this way, the focus point to be focused is not determined, causing hunting, etc., or performing another measurement each time focus is performed. The distance point will be in focus and the photographer's trust will be greatly impaired.
[0016]
(Object of the Invention) Purpose of Is an object that causes hunting when the lens is focused or does not match the user's will Will focus on Focus detection device that can prevent , Camera and focus detection method Is to provide.
[0020]
In order to achieve the above object, the present invention according to claim 1 is directed to focus detection means for executing a focus detection operation for each of a plurality of focus detection areas, and focus detection of the plurality of focus detection areas by the focus detection means. From the result in the screen Defocus amount A grouping means for grouping the plurality of focus detection areas based on a distribution of the at least one focus detection area, and selecting at least one focus detection area from the plurality of focus detection areas based on a grouping result by the grouping means And a focus detection area selected by the selection means Defocus amount And given Defocus amount Comparing means for comparing the selected focus detection area Defocus amount Is given Defocus amount If greater than Defocus amount The lens is driven based on the Defocus amount After the change, the focus detection again in the plurality of focus detection areas, grouping, selection of the focus detection area and a predetermined Defocus amount And repeat the comparison with Defocus amount If it is smaller, the focus detection apparatus has a control unit that controls the selected focus detection area to be focused without performing grouping and selection of the focus detection area again.
[0021]
In order to achieve the above object as well, the present invention as claimed in claim 2 is directed to focus detection means for executing a focus detection operation for each of a plurality of focus detection areas, and the focus of the focus detection areas by the focus detection means. From the detection result Defocus amount A grouping means for grouping the plurality of focus detection areas based on a distribution of the at least one focus detection area, and selecting at least one focus detection area from the plurality of focus detection areas based on a grouping result by the grouping means And a focus detection area selected by the selection means Defocus amount And given Defocus amount Comparing means for comparing the selected focus detection area Defocus amount Is given Defocus amount If greater than Defocus amount The lens is driven based on the Defocus amount After the change, the focus detection in the plurality of focus detection areas again, the selection of the focus detection area based on the first grouping result, and the predetermined Defocus amount And repeat the comparison with Defocus amount If it is smaller, the focus detection apparatus has a control means for controlling the selected focus detection area so that the selected focus detection area is not focused again.
[0022]
Similarly, in order to achieve the above object, according to a third aspect of the present invention, there is provided a focus for executing a focus detection operation on each of a plurality of focus detection areas based on an area sensor and a signal output from the area sensor. From the focus detection results of the plurality of focus detection areas by the detection means and the focus detection means, Defocus amount A grouping means for grouping the plurality of focus detection areas based on the distribution of the at least one focus detection area, and selecting at least one focus detection area from the plurality of focus detection areas based on the grouping result by the grouping means And a focus detection area selected by the selection means Defocus amount And given Defocus amount Comparing means for comparing the selected focus detection area Defocus amount Is given Defocus amount If greater than Defocus amount The lens is driven based on the Defocus amount After the change, the focus detection in the plurality of focus detection areas again, grouping, selection of the focus detection area and a predetermined Defocus amount And repeat the comparison with Defocus amount If smaller, the camera has a control means for controlling the selected focus detection area to be in focus without re-grouping and selecting the focus detection area.
[0023]
In order to achieve the above object as well, the present invention according to claim 4 is a focus for executing a focus detection operation for each of a plurality of focus detection areas based on an area sensor and a signal output from the area sensor. From the focus detection results of the plurality of focus detection areas by the detection means and the focus detection means, Defocus amount A grouping means for grouping the plurality of focus detection areas based on the distribution of the at least one focus detection area, and selecting at least one focus detection area from the plurality of focus detection areas based on the grouping result by the grouping means And a focus detection area selected by the selection means Defocus amount And given Defocus amount Comparing means for comparing the selected focus detection area Defocus amount Is given Defocus amount If greater than Defocus amount The lens is driven based on the Defocus amount After the change, the focus detection in the plurality of focus detection areas again, the selection of the focus detection area based on the first grouping result, and the predetermined Defocus amount And repeat the comparison with Defocus amount If smaller, the camera has a control means for controlling the selected focus detection area to be focused without causing the focus detection area to be selected again.
[0024]
In order to achieve the above object, the present invention according to claim 5 is a focus detection step for executing a focus detection operation for each of a plurality of focus detection regions, and the focus of the plurality of focus detection regions in the focus detection step. A grouping step for grouping the plurality of focus detection areas from the detection result, and a selection step for selecting at least one focus detection area from the plurality of focus detection areas based on the grouping result in the grouping step And the focus detection area selected in the selection step. Defocus amount And given Defocus amount A comparison step for comparing the selected focus detection area Defocus amount Is given Defocus amount If greater than Defocus amount The lens is driven based on the Defocus amount After the change, the focus detection in the plurality of focus detection areas again, grouping, selection of the focus detection area and a predetermined Defocus amount And repeat the comparison with Defocus amount If it is smaller, the focus detection method has a control step for controlling the selected focus detection area to be in focus without re-grouping and selecting the focus detection area.
[0025]
In order to achieve the above object, the present invention according to claim 6 is a focus detection step for executing a focus detection operation for each of a plurality of focus detection regions, and a focus of the plurality of focus detection regions in the focus detection step. A grouping step for grouping the plurality of focus detection areas from the detection result, and a selection step for selecting at least one focus detection area from the plurality of focus detection areas based on the grouping result in the grouping step And the focus detection area selected in the selection step. Defocus amount And given Defocus amount A comparison step for comparing the selected focus detection area Defocus amount Is given Defocus amount If greater than Defocus amount The lens is driven based on the Defocus amount After the change, the focus detection in the plurality of focus detection areas again, the selection of the focus detection area based on the first grouping result, and the predetermined Defocus amount And repeat the comparison with Defocus amount If it is smaller, the focus detection method includes a control step for controlling the selected focus detection area to be focused without causing the focus detection area to be selected again.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on illustrated embodiments.
[0027]
FIG. 3 is a block diagram showing a schematic configuration of the camera according to the first embodiment of the present invention.
[0028]
In FIG. 3, reference numeral 203 denotes a microcomputer, which is an A / D converter that converts an output from an area sensor, which will be described later, into a digital signal, and a memory (RAM) that stores an image signal A / D converted by the A / D converter. And a CPU for performing distance map creation and grouping, which will be described later.
[0029]
Reference numeral 201 denotes an area sensor such as a CCD in which minute light receiving pixels are two-dimensionally arranged, and 202 denotes a sensor driving circuit that drives the area sensor 201. The sensor drive circuit 202 performs serial communication via the data bus DBUS while receiving the AFCOM signal. When sensor drive information is received from the microcomputer 203 by serial communication, the sensor is driven and controlled based on the information.
[0030]
Reference numeral 206 denotes a lens driving circuit that drives the photographing lens based on the distance measurement information selected by the microcomputer 203, and controls the focus adjustment motor and the diaphragm blade control motor of the photographing lens 213. While receiving the LCOM signal from the microcomputer 203, serial communication is performed via the data bus DBUS. When lens drive information is received from the microcomputer 203 by serial communication, the lens is driven and controlled by the information. At the same time, various kinds of lens information (focal length information, etc.) are sent to the microcomputer 203 by serial communication.
[0031]
207 is a switch (SW1) that is turned on by a first stroke of a release button (not shown), and 208 is a switch (SW2) that is turned on by a second stroke of a release button (not shown).
[0032]
Reference numeral 214 denotes a switch sense circuit, which is a circuit for reading a switch state indicating a camera state and a switch for setting a shooting condition by a photographer and sending it to the microcomputer 203. While receiving a SWCOM signal, Switch data is sent to the microcomputer 203 by serial communication via the bus DBUS. Also, the dial value is counted up or down by the input value of the electronic dial 210, and the count value is sent to the microcomputer 203 by serial communication via the data bus DBUS while receiving the SWCOM signal.
[0033]
A shutter control circuit 204 controls opening / closing of the shutter, and a film control circuit 205 controls film feeding.
[0034]
Next, a series of operations executed in the microcomputer 203 will be described with reference to the flowchart of FIG.
[0035]
In step # 300, the camera is turned on due to factors such as the camera main switch being pressed, and the process proceeds to step # 301. In step # 301, the mode is switched and the set value is switched based on the information of the switch sense circuit 214. If there is a change, the display data and the display data are displayed by communicating with a liquid crystal display circuit (not shown). Correct the color. In the subsequent step # 302, it is determined whether or not the switch SW1 is ON. If it is ON, the process proceeds to step # 306 to perform the photometric operation, and if it remains OFF, the process proceeds to step # 303. .
[0036]
Here, it is assumed that the switch SW1 remains OFF, and the process proceeds to step # 303.
[0037]
In step # 303, it is determined whether or not the power is to be turned off. Via step # 301 The process returns to the check of the switch SW1 in step # 302. That is, when the power of the camera rises for some reason, the switch state is checked and the display is switched by turning on the power for a certain period of time. If the power is turned off in step # 303, the process proceeds to step # 304, and the display of unnecessary parts in the camera finder or outside is displayed on the liquid crystal display. In circuit Turn off the light and turn off the power. Then, in the next step # 305, a series of operations is terminated.
[0038]
If it is determined in step # 302 that the switch SW1 is turned on, the process proceeds to step # 306 as described above. Here, the photometry circuit (not shown) is operated to capture the reflected light from the subject and perform A / D conversion. To obtain photometric information. Then, an exposure condition (aperture, shutter speed) is calculated. In the next step # 307, subroutine automatic selection AF is performed. The detailed operation of this subroutine automatic selection AF will be described later. In the subsequent step # 308, the AV value and TV value obtained in step # 306 are displayed on the in-finder liquid crystal display device and the external liquid crystal display device by a liquid crystal display circuit (not shown).
[0039]
In step # 309, it is determined whether or not the camera is in a state that permits release. For example, when the AF mode is “one-shot mode”, release is permitted if the focus detection result of step # 307 is “in-focus state”, and the process proceeds to step # 310, which will be described later, to check the switch SW2. On the other hand, if it is not “in-focus state”, the process returns to step # 301. After returning to step # 301, the mode and the like are displayed as necessary as in the case described above, and the process proceeds to step # 302 for checking the switch SW1. If the switch SW1 is ON, photometry, distance measurement, and display are performed again (steps # 302 → # 306 → # 307 → # 308), and the camera state may permit release again in step # 309. It is determined whether or not it is in a state.
[0040]
If the release is permitted in step # 309, the process proceeds to step # 310, where it is determined whether or not the switch SW2 is ON. If it is ON, the process proceeds to step # 311 in order to perform the photographing operation. When the switch SW2 is OFF, the process returns to Step # 301 and Step # 302 for checking the switch SW1, and when the switch SW1 is ON at Step # 302, photometry, distance measurement, and display are performed again (Step S302). # 302 → # 306 → # 307 → # 308).
[0041]
If the switch SW2 is ON in step # 310, the process proceeds to step # 311 to perform the photographing operation as described above. Here, the click return mirror is raised by a charge motor control circuit (not shown), and The aperture amount determined in step # 306 is communicated to the taking lens 213 by the lens driving circuit 206, and the aperture operation is performed so that the set exposure amount can be obtained. In the next step # 312, travel control of a shutter front curtain and a rear curtain (not shown) is performed using the shutter control circuit 204 so that the TV amount determined in step # 306 can be obtained. In the subsequent step # 313, the quick return mirror is lowered by a charge motor control circuit (not shown), and at the same time, the shutter is charged, and the diaphragm that has been throttled in step # 306 is returned to the open position. In step # 314, the film control circuit 205 is used to control a feed motor (not shown) to wind the film.
[0042]
This completes the series of camera operations.
[0043]
In this sequence, processing when the operation of the camera is different from normal (for example, when the film is stretched) is omitted because it is irrelevant to the present invention.
[0044]
Next, the subroutine “automatic selection AF” called in step # 307 of FIG. 4 will be described in detail with reference to the flowchart of FIG.
[0045]
In step a101, the program sequence is shifted from step # 306 in FIG. 4, and execution of subroutine automatic selection AF is started. First, in step a102, the area sensor 201 is driven using the sensor drive circuit 202, the photoelectric conversion sensor is accumulated and the sensor output is taken in to detect the focus of a plurality of areas, and the A / D value is obtained. To calculate focus information for each focus detection area. Based on these focus detection results, the defocus amount is calculated by an existing algorithm, and multipoint focus detection is performed.
[0046]
In the next step a103, grouping is performed based on the detected defocus amount (defocus map is created). As described above, in the grouping method, if the difference in defocus between two adjacent blocks is equal to or less than a predetermined value, the determination that the two blocks form the same object is performed on all adjacent blocks. Since the method of applying is already known, further explanation is omitted. By making such a determination, it is possible to obtain data obtained by dividing the shooting screen into regions for each object. (The area division data grouped by this defocus is called a defocus map.)
For example, when focus detection is performed at the focus detection points arranged as shown in FIG. 9B in the shooting scene as shown in FIG. 9A when the lens is in the closest position, at each focus detection point, As shown in FIG. 5A1, the defocus amount is detected (the undetectable area is blank). The defocus map created at this time is as shown in FIG. Since the lens is at the closest end and the defocus amount is large as a whole, the focus of the face portion of a person with contrast can be detected, but there are many other portions where focus detection is impossible. In the defocus map area, each person's face part is recognized as two areas (areas b1.1 and b1.2), and the person's clothes part forms one area (area b1.3). ing. The wall portion is hardly recognized as a region because focus detection is almost impossible.
[0047]
In the next step a104, the main subject is determined from all objects (groups) constituting the screen. Factors for determining the main subject are determined in consideration of the size and inclination of the object, the distance, the position on the screen, and the like. When the main subject is determined, a focus detection point representing the group is determined, and the defocus amount of the focus detection point is set as the defocus amount of the group, that is, the main subject.
[0048]
In the example of FIGS. 5A1 and 5B1, the region b1.1 is selected as the main subject from the regions b1.1, b1.2, and b1.3, and the region b1.1 is selected from the region b1.1. (B1) Focus detection point A defocus amount of “−14.7” (absolute value “14.7”) is selected as the defocus amount of the main subject.
[0049]
In the next step a105, the defocus amount of the main subject is compared with the defocus determination threshold value. Branch to step a107. For example, if the defocus amount determination threshold is “0.1”, the current main subject is “−14.7” (absolute value “14.7”), which is larger than the threshold. Here, the case where the defocus amount of the main subject is larger than the threshold will be described first. At this time, the process proceeds to step a106.
[0050]
In step a106, after calculating the lens drive amount based on the defocus amount of the main subject, the lens drive amount is communicated to the lens control circuit 206 to drive the lens. After driving the lens, the process returns to step a102 and the focus detection is performed again. In steps a103 to a104, a defocus map is created again, the main subject is determined, and the defocus amount is obtained.
[0051]
In the above example, when the focus is detected again after the lens is driven based on the previously determined defocus amount of the main subject, the defocus as shown in FIG. 5 (a2) is obtained at each focus detection point. The amount is detected. The defocus map created at this time is as shown in FIG. Since the lens is driven from the closest end, the previous defocus amount of the main subject is small. When a defocus map is created again with the defocus amount detected this time, the result is as shown in FIG. In the defocus map area, each person's face part is recognized as two areas (areas b2.1 and b2.2), and one part of the person forms one area (area b2.3). Yes.
[0052]
This time, since the focus on the wall on the right person was detected, a new region b2.4 is formed. Areas b2.1 and b2.2 are areas corresponding to the areas b1.1 and b1.2 of the defocus map created by the first distance measurement, but the areas that can be detected slightly increase due to the increase in focus detectable areas. It is getting bigger. Select a region from these four regions according to a predetermined algorithm The Then, the area b2.2 is selected as the main subject area. Focus detection points representing the group from the area b2.2 are shown in FIG. Focus detection point 2 and the defocus amount is set as the defocus amount of the main subject.
[0053]
In step a105, the defocus amount is compared again. If the defocus amount is large, the process proceeds to step a106 to drive the lens.
[0054]
As described above, in step a105, steps a102 to a106 are repeatedly executed until the defocus amount decreases, and the defocus map is recreated each time to determine the main subject.
[0055]
If the defocus amount of the main subject becomes smaller than the threshold value in step a105, the process proceeds to step a107. In the above example, decided Focus detection point The defocus amount of 2 is “−0.97” (the absolute value is “0.97”), which is smaller than the defocus amount determination threshold “0.1” (comparison is performed with the absolute value), and the process branches to step a107. In step a107, the focus detection point is determined at the position calculated last in step a104. Thereafter, the defocus map is not created and the main subject is not determined again.
[0056]
In the above example, Focus detection point 2 is determined as the position of the final focus detection point, and thereafter focus detection is performed only at this focus detection point.
[0057]
In the next step a108, it is determined whether the focus detection point determined in step a107, that is, the defocus amount of the main subject is within the in-focus range. If it is in focus, the process proceeds to step a111, and if not, the process proceeds to step a109. In step a109, after calculating the lens driving amount based on the defocus amount of the main subject determined in step a107, the lens driving amount is communicated to the lens control circuit 206 to drive the lens. In the next step a110, focus detection of the focus detection point determined in step a107 is performed after driving the lens. Thereafter, the process returns to step a108 to perform in-focus determination.
[0058]
After the focus detection point (main subject) is determined in step a107, focus detection is performed only at the focus detection point, and steps a108 to a110 are repeated until focusing is achieved. As can be seen here, once the main subject is determined, the defocus map is not created and the main subject is not determined.
[0059]
If it is determined in step a108 that the in-focus state is obtained, the process proceeds to step a111 to set the “in-focus state”. Then, the process proceeds to step a112, and this subroutine is returned.
[0060]
In this subroutine, the case where focus detection is performed until focus is achieved (the sequence when focus is not achieved is omitted). However, in actuality, when focus detection is impossible or predetermined Since processing is performed when the lens is not in focus even if the lens is driven a number of times, the subroutine is not necessarily returned in the “in-focus state”.
[0061]
As described above, when focus detection is performed at a plurality of focus detection points, and area division is performed based on the result, the main subject area is determined from the divided areas and focus adjustment is performed, the focus of the determined main subject is determined. Until the detection result is within the predetermined range, the lens is driven while repeatedly dividing the area and determining the main subject region, and when the focus detection result of the main subject is within the predetermined range, the focus adjustment is performed on the determined main subject. Therefore, it is possible to perform focus detection point selection that matches the will without performing hunting or erroneous selection (selecting a subject that does not match the will of the photographer).
[0062]
(Second Embodiment)
FIG. 2 is a flowchart showing a subroutine “automatic selection AF” of the camera according to the second embodiment of the present invention. Note that the schematic configuration of the camera and other operations are the same as those in FIGS. 3 and 4 described in the first embodiment, and therefore description thereof is omitted here.
[0063]
When the subroutine “automatic selection AF” is called in step # 307 of FIG. 4, the operation starts from step z101. z102 , The area sensor 201 is driven using the sensor driving circuit 202, the defocus amount is calculated by an existing algorithm, and multipoint focus detection is performed. In the next step z103, grouping is performed based on the detected defocus amount. In step z104, the main subject is determined from all objects (groups) constituting the screen, and a focus detection point representing the group is determined. The defocus amount of the focus detection point is set as the defocus amount of the group, that is, the main subject.
[0064]
In the next step z105, the defocus amount of the main subject is compared with the defocus determination threshold value.
[0065]
First, a case where the defocus amount of the main subject is larger than the threshold value and the process proceeds to step z106 will be described.
[0066]
In step z106, the lens drive amount is communicated to the lens control circuit 206 based on the defocus amount of the main subject to drive the lens. Then, in the next step z107, after the lens is driven, multipoint focus detection is performed again, and the process returns to step z104), where the main subject is determined again and the defocus amount is obtained.
[0067]
In the second embodiment, since the defocus map is not recreated, the main subject is determined by the region division determined first. Since the defocus map is not recreated, the calculation time is greatly shortened, and the size and number of areas do not change every calculation. Further, when the area division is decided first, it is possible to decide only the rough division, not the division that strictly separates the individual focus detection points as in the first embodiment. . The division of the area is not necessarily determined based on the first distance measurement result, but may be determined after performing the focus adjustment operation several times.
[0068]
Steps z104 to z107 are repeatedly executed until it is determined in step z105 that the defocus amount is small, and the main subject is determined by the region division determined first.
[0069]
If the defocus amount of the main subject becomes smaller than the threshold value in step z105, the process proceeds to step z108. In step z108, the focus detection point is determined at the position calculated last in step z104. Thereafter, the main subject is not re-determined. In the subsequent step z109, it is determined whether the focus detection point determined in step z108, that is, the defocus amount of the main subject is within the in-focus range. If in focus, go to step z112, otherwise go to step z112 z110 Proceed to
[0070]
In step z110, the lens drive amount is calculated based on the defocus amount of the main subject determined in step z108, the lens drive amount is communicated to the lens control circuit 206, and the lens is driven. In the next step z111, the lens is driven and then determined in step z107. Focus detection point Focus detection is performed. Thereafter, the process returns to step z109 to perform in-focus determination.
[0071]
After the focus detection point (main subject) is determined in step z108, focus detection is performed only at the focus detection point, and steps z109 to z111 are repeated until focusing is achieved. As can be seen, once the main subject is determined, the main subject is not determined.
[0072]
When it is determined that the in-focus state is obtained in step z109, the process proceeds to step z112, and the “in-focus state” is set. In the next step z113, this subroutine is returned.
[0073]
In this subroutine, the case where focus detection is performed until focus is achieved (the sequence when focus is not achieved is omitted). However, in actuality, when focus detection is impossible or predetermined Since processing is performed when the lens is not in focus even if the lens is driven a number of times, the subroutine is not necessarily returned in the “in-focus state”.
[0074]
As described above, when ranging is performed at a plurality of focus detection points, the region is divided based on the result, and the main subject region is determined from the divided regions to perform focus adjustment, the focus of the determined main subject is determined. Until the detection result is within the predetermined range, the lens is driven while repeatedly determining the main subject area in the determined area division, and when the focus detection result of the main subject is within the predetermined range, focus adjustment is performed on the determined main subject. Thus, focus detection point selection that matches the will can be performed without performing hunting or erroneous selection (selecting a subject that does not match the will of the photographer). In addition, since the area division is not repeated, the amount of calculation is reduced and the calculation time is shortened.
[0075]
( First reference technology example ) In the first embodiment, the defocus detection type device has been described as an example. However, the distance measurement device that detects the distance can similarly perform region division and focus adjustment. . In this case, a distance map is created at a portion corresponding to step a103 in FIG. 1. In step a105, the distance of the main subject is compared with the distance at which the photographic lens is focused, It is determined whether the difference is within a predetermined range.
[0076]
( Second reference technology example In the second embodiment, the apparatus for detecting the defocus has been described as an example. However, the distance measuring apparatus for detecting the distance can similarly perform the region division to adjust the focus. In this case, a distance map is created at a portion corresponding to step z103 in FIG. 2, and in step z105, the distance of the main subject is compared with the distance at which the photographic lens is focused, It is determined whether the difference is within a predetermined range.
[0077]
(Correspondence between Invention and Embodiment) First Embodiment And second In the embodiment, the part of the microcomputer 203 that executes the operations of steps a102 and z102 in FIGS. 1 and 2 is the focus detection means according to claims 1-4 or the focus detection step according to claims 5 and 6, The part that executes the operations of steps a103 and z103 is the grouping means according to claims 1-4 or the grouping step of claims 5 and 6, and the part that executes the operations of steps a104 and z104 is claims 1-4. The portion for executing the operations of steps a105 and z105 in the selecting means described in claim 5 or the selecting step described in claims 5 and 6 is the same as the comparing means described in claims 1-4 or the comparing step described in claims 5 and 6. The part for executing the operations of a106 → a102 → a103 → a104 and steps a105 → a107 → a108 The control means or claim 5 control step described according correspond respectively.
[0078]
Also step z105 → z106 → z107 → z104 and step z105 → z108 → z109 The portions for executing the operations correspond to the control means according to claims 2 and 4 or the control step according to claim 6, respectively.
[0079]
The above is the correspondence between each configuration of the embodiment and each configuration of the present invention. However, the present invention is not limited to the configuration of the embodiment, and the functions shown in the claims or the embodiment It goes without saying that any configuration may be used as long as the function of the can be achieved.
[0080]
(Modification)
Although the present invention is applied to a camera such as a single-lens reflex camera or a video camera as an example, it may be a focus detection device, a distance measuring device, an automatic focus adjustment device mounted on the camera, Can be applied to an environment recognition device such as an air conditioner (for example, used as a device for recognizing a person and setting a wind direction in the direction) or a car (used as a person recognition device).
[0081]
In addition, the present invention can also be applied to an optical device including a distance measuring device and a focus detection device to which the present invention is applied, such as binoculars and a game machine.
[0082]
【The invention's effect】
As described above, according to the present invention, an object that causes hunting when the lens is focused or does not match the user's will Focus detection device, camera, or focus detection method capable of preventing focusing on the camera Can be provided.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an operation during automatic selection AF of a camera according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing an operation during automatic selection AF of the camera according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a schematic configuration of a camera according to each embodiment of the present invention.
FIG. 4 is a flowchart for explaining the main operation of the camera according to each embodiment of the present invention.
FIG. 5 is a diagram of a defocus amount detected by automatic selection AF and a defocus map created based on the defocus amount according to the first embodiment of the present invention.
FIG. 6 is a diagram illustrating an example of a shooting scene for explaining a conventional example.
7 is a diagram showing an example of a distance map in FIG. 6. FIG.
FIG. 8 is a diagram illustrating an example when FIG. 7 is grouped.
FIG. 9 is a distribution diagram of focus detection points and an example of a photographing scene for explaining a conventional example and the present invention.
FIG. 10 is a diagram illustrating an example of a conventional defocus map (region division).
[Explanation of symbols]
201 Area sensor
202 Sensor drive circuit
203 Microcomputer
206 Lens drive circuit
207 Switch (SW1) that is turned on by the first stroke of the release button
208 Switch (SW2) that is turned on by the second stroke of the release button
213 Photo lens
214 Switch sense circuit

Claims (6)

Focus detection means for executing a focus detection operation for each of a plurality of focus detection areas;
Grouping means for grouping the plurality of focus detection areas based on the distribution of defocus amounts in the screen from the focus detection results of the plurality of focus detection areas by the focus detection means;
Selection means for selecting at least one focus detection area from a plurality of focus detection areas based on the grouping result by the grouping means;
Comparing means for comparing the defocus amount and the predetermined defocus amount of the focus detection area selected by said selecting means,
If the defocus amount of the elected focus detection area is larger than the predetermined defocus amount to drive the lens based on the defocus amount, after the defocus amount in accordance with the said lens drive is changed, again The focus detection in the plurality of focus detection areas, grouping, selection of the focus detection area and comparison with a predetermined defocus amount are repeated, and if the comparison is smaller than the predetermined defocus amount , A focus detection apparatus comprising: control means for controlling the selected focus detection area to be focused without performing grouping and selection of the focus detection area. Focus detection means for executing a focus detection operation for each of a plurality of focus detection areas;
Grouping means for grouping the plurality of focus detection areas based on the distribution of defocus amounts in the screen from the focus detection results of the plurality of focus detection areas by the focus detection means;
Selection means for selecting at least one focus detection area from a plurality of focus detection areas based on the grouping result by the grouping means;
Comparing means for comparing the defocus amount and the predetermined defocus amount of the focus detection area selected by said selecting means,
If the defocus amount of the elected focus detection area is larger than the predetermined defocus amount to drive the lens based on the defocus amount, after the defocus amount in accordance with the said lens drive is changed, again The focus detection in the plurality of focus detection areas, the selection of the focus detection area based on the first grouping result, and the comparison with the predetermined defocus amount are repeated, and at the time of the comparison, it is smaller than the predetermined defocus amount. And a control means for controlling the selected focus detection area to be focused without causing the focus detection area to be selected again. An area sensor,
A focus detection unit that performs a focus detection operation on each of a plurality of focus detection areas based on a signal output from the area sensor;
Grouping means for grouping the plurality of focus detection areas based on the distribution of defocus amounts in the screen from the focus detection results of the plurality of focus detection areas by the focus detection means;
Selection means for selecting at least one focus detection area from a plurality of focus detection areas based on the grouping result by the grouping means;
Comparing means for comparing the defocus amount and the predetermined defocus amount of the focus detection area selected by said selecting means,
If the defocus amount of the elected focus detection area is larger than the predetermined defocus amount to drive the lens based on the defocus amount, after the defocus amount in accordance with the said lens drive is changed, again The focus detection in the plurality of focus detection areas, grouping, selection of the focus detection area and comparison with a predetermined defocus amount are repeated, and if the comparison is smaller than the predetermined defocus amount , A camera comprising: control means for controlling the selected focus detection area to be focused without causing grouping and selection of the focus detection area. An area sensor,
A focus detection unit that performs a focus detection operation on each of a plurality of focus detection areas based on a signal output from the area sensor;
Grouping means for grouping the plurality of focus detection areas based on the distribution of defocus amounts in the screen from the focus detection results of the plurality of focus detection areas by the focus detection means;
Selection means for selecting at least one focus detection area from a plurality of focus detection areas based on the grouping result by the grouping means;
Comparing means for comparing the defocus amount and the predetermined defocus amount of the focus detection area selected by said selecting means,
If the defocus amount of the elected focus detection area is larger than the predetermined defocus amount to drive the lens based on the defocus amount, after the defocus amount in accordance with the said lens drive is changed, again The focus detection in the plurality of focus detection areas, the selection of the focus detection area based on the first grouping result, and the comparison with the predetermined defocus amount are repeated, and at the time of the comparison, the smaller than the predetermined defocus amount And a control means for controlling the selected focus detection area to be focused without causing the focus detection area to be selected again. A focus detection step for performing a focus detection operation on each of the plurality of focus detection regions;
A grouping step of grouping the plurality of focus detection areas from the focus detection results of the plurality of focus detection areas in the focus detection step;
A selection step of selecting at least one focus detection region from a plurality of focus detection regions based on the grouping result in the grouping step;
A comparing step of comparing a defocus amount and a predetermined defocus amount of the elected focus detection area in the selection step,
If the defocus amount of the elected focus detection area is larger than the predetermined defocus amount to drive the lens based on the defocus amount, after the defocus amount in accordance with the said lens drive is changed, again The focus detection in the plurality of focus detection areas, grouping, selection of the focus detection area and comparison with a predetermined defocus amount are repeated, and if the comparison is smaller than the predetermined defocus amount , And a control step of controlling the selected focus detection area to be focused without causing grouping and selection of the focus detection area. A focus detection step for performing a focus detection operation on each of the plurality of focus detection regions;
A grouping step of grouping the plurality of focus detection areas from the focus detection results of the plurality of focus detection areas in the focus detection step;
A selection step of selecting at least one focus detection region from a plurality of focus detection regions based on the grouping result in the grouping step;
A comparing step of comparing a defocus amount and a predetermined defocus amount of the elected focus detection area in the selection step,
If the defocus amount of the elected focus detection area is larger than the predetermined defocus amount to drive the lens based on the defocus amount, after the defocus amount in accordance with the said lens drive is changed, again The focus detection in the plurality of focus detection areas, the selection of the focus detection area based on the first grouping result, and the comparison with the predetermined defocus amount are repeated, and at the time of the comparison, the smaller than the predetermined defocus amount And a control step for controlling the selected focus detection area to be focused without causing the focus detection area to be selected again.

Images