Image pickup apparatus

Provided is an image pickup apparatus including: a zoom lens unit which moves during zooming; a focus lens unit which moves during focusing; a zoom operation switch having a function for driving the zoom lens unit; a focus detection unit for detecting a focus state on an object located in a focusing area selected from multiple focusing areas within an imaging area; and a drive unit for driving the focus lens unit based on a result obtained by detection of the focus detection unit, in which the zoom operation switch further has a function for switching the selected focusing area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image pickup apparatus having an automatic focusing function.

2. Description of the Related Art

Up to now, a method of intentionally moving a focusing area by a photographer has been used in order to perform a further advanced focus operation in a handy type image pickup apparatus having an automatic focusing function.

US Patent Published Application No. 2006/0033834 and US Patent Published Application No. 2006/0083506 discuss a method of adjustably moving the focusing area displayed on a viewfinder by a photographer using a control unit such as a joystick or a trackball while the image pickup apparatus is mounted on a tripod.

Japanese Patent Application Laid-Open No. H10-173980 discusses a method of indicating the focusing area by bringing a finger of the photographer into direct contact with a touch panel while the image pickup apparatus is carried on the shoulder.

However, any of the conventional examples described above requires a specific unit or part for moving the focusing area, and hence the entire system is increased in size or the structure is complicated because of an increase in the number of parts. For the same reason, in order to move the focusing area by the photographer, the specific operation for moving the focusing area, such as the operation of the joystick or the finger operation of the touch panel is required. Therefore, a problem occurs that the degree of freedom of shooting reduces.

SUMMARY OF THE INVENTION

The present invention has been made to solve the problems described above. An objective of the present invention is to provide an image pickup apparatus capable of selecting a focusing area without an increase in the number of parts and a reduction in the degree of freedom of shooting.

In order to achieve the above-mentioned objective, an image pickup apparatus according to the present invention includes: a zoom electric operation unit for electrically driving a zoom lens unit; a zoom drive switch unit for switching between an electric driving of the zoom lens unit and a manual driving of the zoom lens unit; a focus detection unit for detecting a focus state on an object located in each of multiple focusing areas within an imaging area; an area selection unit for selecting a focusing area from the multiple focusing areas; and an automatic focusing unit for driving a focus lens unit to bring an object located in the focusing area selected by the area selection unit into an in-focus state, in which when the zoom drive switch unit selects the manual driving of the zoom lens unit, the zoom electric operation unit functions as the area selection unit.

DESCRIPTION OF THE EMBODIMENTS

The present invention is described in detail with reference to illustrated embodiments.

FIG. 1is a block circuit structural diagram illustrating an image pickup apparatus according to Embodiment 1. The image pickup apparatus illustrated inFIG. 1includes an automatic focusing lens based on a so-called phase difference method. A drive unit2is attached to a lens main body1. In the lens main body1, a focus lens unit (focusing lens unit)3, a half mirror4, and a zoom lens unit (magnification-varying lens unit)5are arranged along an optical axis. A camera main body6is provided in the rear of the lens main body1. A mirror7, an image pickup lens8, and a through camera lens (TCL) module9are arranged in a reflection direction of the half mirror4.

The drive unit2contains a control circuit10. An output of the TCL module9is connected to the control circuit10. Outputs of the control circuit10are connected to a focus drive actuator11and a zoom drive actuator12. An output of the focus drive actuator11is connected to the focus lens unit3. An output of the zoom drive actuator12is connected to the zoom lens unit5through an actuator gear13, an idler gear14, and a zoom operation ring15. The actuator gear13and the idler gear14are connected to or disconnected from each other by a zoom drive switch unit (unit or switch)16including a clutch. The movement of the zoom drive switch unit16may be detected by a detector17. Further, a zoom electric operation unit18including a zoom electric operation switch and a seesaw switch, a setting unit19, an AUX switch20serving as a supplementary switch, and electrical parts of the camera main body6are connected to the control circuit10.

Ranging information of an object (that is, light from the object) is led to the TCL module9through the half mirror4, the mirror7, and the image pickup lens8. In the TCL module9, CCD sensors are arranged alternately in an A-column and a B-column. The ranging, that is, the measuring of the distance between the object in the focusing area and the image pick apparatus, is performed based on the principle of triangulation.

The ranging information of the object which is obtained by the TCL module9is transmitted to the control circuit10of the drive unit2. A command signal for focusing is transmitted to the focus drive actuator11. The focus drive actuator11and the focus lens unit3are mechanically connected to each other. When the focus drive actuator11is driven by a predetermined amount, the focus lens unit3is moved in an optical axis direction through a drive mechanism such as a screw feed mechanism, to thereby achieve an in-focus state.

The zoom lens unit5is mechanically connected to the zoom operation ring15of the lens main body1. A drive gear is provided in an outer circumference portion of the zoom operation ring15. The idler gear14is provided in the drive unit2to connect the zoom operation ring15and the actuator gear13. The actuator gear13is connected to the zoom drive actuator12, and hence a driving force of the zoom drive actuator12is transferred (as rotational driving force or rotational force) to the zoom operation ring15through the actuator gear13and the idler gear14.

A photographer uses the zoom drive switch unit16to move the idler gear14in the optical axis direction based on a shooting condition. Therefore, the idler gear14is connected to or disconnected from the actuator gear13to switch between electric driving and manual driving of the zoom lens unit. At this time, the connection between the idler gear14and the zoom operation ring15is always maintained in any case. When the idler gear14is connected to the actuator gear13, an electric zoom mode is set. When the idler gear14is disconnected from the actuator gear13as illustrated inFIG. 1, a manual zoom mode is set.

The electric zoom mode in which the zoom lens unit is electrically driven is a mode in which the zoom electric operation unit18is operated to drive the zoom lens unit5by a motor or the like, to thereby change a focal length of the entire optical system for zooming. In other words, the electric zoom mode is a mode in which zooming is performed by the zoom electric operation unit18or a mode in which the zoom lens unit5is driven by a motor or the like based on a command value from the zoom electric operation unit18.

The manual zoom mode in which the zoom lens unit is driven manually is a mode in which zooming is performed using an operation unit such as the zoom operation ring15, which is different from the zoom electric operation unit18. As in this embodiment, it is desirable to mechanically connect the zoom operation ring15to the zoom lens unit5. Even when the zoom lens unit5is moved by a motor based on the amount of rotation of the zoom operation ring15, there is no problem.

The electric zoom mode in which the zooming is performed by the operation of the zoom electric operation unit18and the manual zoom mode in which the zooming is performed by the operation of the zoom operation ring15are switched using the zoom drive switch unit described above. During the electric zoom mode, the zoom electric operation unit may serve to operate zooming. During the manual zoom mode, the zoom electric operation unit may serve to switch a focusing area. In other words, the function of the zoom electric operation unit may be switched by the operation of the zoom drive switch unit.

During the electric zoom mode in this embodiment, the zoom lens unit5is driven for zooming by the zoom electric operation unit18. However, the image of the object may be enlarged or reduced by image processing while the zoom lens unit5is fixed.

In this case, the switching of the zoom drive switch unit16is detected by the detector17to recognize an electric zoom mode/manual zoom mode state. A result obtained by detection is transmitted to the control circuit10. When the photographer operates the zoom electric operation unit18during zooming in the electric zoom mode, a command indicating a command value corresponding to the amount of press is transmitted to the control circuit10. A command signal for driving the zoom lens unit is sent to the zoom drive actuator12in response to the transmitted command. The zoom electric operation unit18can be movable along an arc in directions indicated by arrows so as to be capable of performing a two-way press operation. When the zoom electric operation unit18is tilted to one side (one operation is performed), the zoom lens unit5moves in a telephoto direction. When the zoom electric operation unit18is tilted to the other side (the other operation is performed), the zoom lens unit5moves in a wide-angle direction.

As illustrated inFIG. 2, the drive unit2is provided with the setting unit19such as a panel, which is capable of arbitrarily setting various shooting parameters such as switch assignment information and an electric zoom speed by the photographer.

As illustrated inFIG. 3, a menu for assigning, to the movement operation of the focusing area, the function of the zoom electric operation unit18in the manual zoom mode is provided to the setting unit19. In this embodiment, a state in which the menu is enabled is set. Setting information of the setting unit19is transmitted to the control circuit10, and hence the assignment is performed such that the operation of the zoom electric operation unit18functions to move the focusing area. Note that there are plural of focusing areas in the imaging area. When performing an automatic focusing operation, the focus state on an object in one of (or in a part of) the focusing area among the multiple focusing areas is detected to thereby perform the automatic focusing operation (or to move the focus lens unit) based on the detection.

As a result, when the photographer operates the zoom electric operation unit18, the control circuit10sends, to the camera main body6, a command signal for moving the automatic focusing area displayed on a viewfinder provided in the camera main body6, based on the details of operation of the zoom electric operation unit18. InFIG. 3, while the menu is disabled, that is, while an OFF value is set for the automatic focusing area, even when the photographer operates the zoom electric operation unit18, the control circuit10does not respond to the operation. In other words, the control circuit10does not send the command signal for moving the automatic focusing area and the command signal for driving the zoom drive actuator12and thus does not perform any operation.

FIGS. 4A to 4Cillustrate typical examples of states of objects displayed on the viewfinder of the camera main body6. As described above, by ranging as a result obtained by phase difference detection by the phase difference method, all distance information corresponding to the focus states of the respective objects becomes obvious. As illustrated inFIG. 4A, a reference automatic focusing area for focus operation which is located in the center of an imaging area at the time of starting shooting, a mark for a front focus object which is located closest to the reference automatic focusing area on a near side, and a mark for a rear focus object which is located closest to the reference automatic focusing area on a far side are displayed on the viewfinder. In this embodiment, different shapes are used for the respective marks to display multiple automatic focusing areas. For example, the reference automatic focusing area is marked with an open square, the front focus object is marked with an open triangle, and the rear focus object is marked with an open circle. Note that marks which have the same shape but different colors may be displayed. The number of display points for each of the front focus object and the rear focus object may be not only one but also two or more for each of the front- and rear-focus objects.

As described above, in the manual zoom mode using the setting unit19, the automatic focusing area movement function is assigned to the zoom electric operation unit18. When the photographer operates the zoom electric operation unit18in a T-direction to perform area selection, as illustrated inFIG. 4B, the reference automatic focusing area is moved from a person located at the center to a person located closest on a rear side of the object which is presently in the reference automatic focusing area.

When the zoom electric operation unit18is operated in the T-direction again, as illustrated inFIG. 4C, the reference automatic focusing area is moved to a tree which is an object located closest on a rear side of the object which is presently in the reference automatic focusing area. When any operation is not performed by the photographer during a predetermined time period after the movement of the reference automatic focusing area, the control circuit10recognizes that the reference automatic focusing area has reached a desired area. Then, an actual automatic focusing detection or focusing operation starts. The predetermined time is arbitrarily set using the setting unit19by the photographer. Within the predetermined time, the reference automatic focusing area is moved in a depth direction at any time by the number of presses of the zoom electric operation unit18which is operated in the T-direction by the photographer.

In contrast to this, when the photographer operates the zoom electric operation unit18in a W-direction, the reference automatic focusing area is moved to a person located closest on a front side of the object which is presently in the reference automatic focusing area. A relationship between the T/W directions of the zoom electric operation unit18and the moving directions of the automatic focusing area may be reversed to the relationship in this embodiment, and such setting may be performed by the setting unit19.

The case where the automatic focusing area is moved by the zoom electric operation unit18during the manual zoom mode is described. However, there is a case where the automatic focusing area is moved by the zoom electric operation unit18during the electric zoom mode.

A function assigned to the AUX switch20of the drive unit2may be changed by the setting unit19. For example, a function associated with a video recording, a return, or the movement of the automatic focusing area may be assigned. In an example illustrated inFIG. 5, the function associated with the movement of the automatic focusing area is assigned to the AUX switch20. When the photographer presses the AUX switch20, the automatic focusing area movement function is assigned to the zoom electric operation unit18as described above even in the case of the electric zoom mode. When the AUX switch20is pressed again after desired focusing is realized, an original zoom operation function is assigned again to the zoom electric operation unit18.

FIG. 6is a flowchart illustrating the case where the zoom operation function is assigned to the zoom electric operation unit18and the case where the automatic focusing area movement function is assigned thereto. First, whether the zoom mode is the electric drive mode or the manual drive mode is determined in Step S101.

In the case of the electric zoom mode, whether or not the AUX switch20is pressed to be turned ON is determined in Step S102. When the AUX switch20is pressed to be turned ON, processing goes to Step S104and the automatic focusing area movement function is assigned to the zoom electric operation unit18. When it is determined in Step S105that the AUX switch20is pressed to be turned ON again, processing goes to Step S103and a normal zoom operation function is assigned to the zoom electric operation unit18. When it is determined in Step S102that the AUX switch20is not pressed and remains in an OFF state, processing goes to Step S103and the normal zoom operation function is assigned to the zoom electric operation unit18. Then, processing is completed in Step S106.

When the manual zoom mode is determined in Step S101, processing goes to Step S107and the automatic focusing area (AF area) movement function is assigned to the zoom electric operation unit18. Then, processing goes to Step S108. When it is determined in Step S108that the AUX switch20is not pressed, that is, when the AUX switch20is not operated because of the selection of the manual zoom mode, processing goes to Step S110. Then, processing is completed in Step S106while the zoom electric operation unit18retains an automatic focusing area selection function. Note that the phrase “the AUX switch20is in the OFF state” means that the AUX switch20is not operated or the AUX switch20is operated an even number of times.

Next, when the AUX switch20is pressed during the manual zoom mode, processing goes to step S109. Then, the assignment of the automatic focusing area movement function to the zoom electric operation unit18is cancelled, and hence the operation itself of the zoom electric operation unit18is nullified. Note that the case where the AUX switch20is operated is a case where the AUX switch20is operated an odd number of times, including a case where the AUX switch20is operated or pressed one time. Steps S108, S109, and S110may be omitted. In other words, in the case of the manual zoom mode, the automatic focusing area selection function may be always assigned to the zoom electric operation unit18.

Even after processing reaches END of Step S106, the function of the zoom electric operation unit18may be changed as appropriate by the operation of the AUX switch20. When manual zooming is switched to electric zooming or when electric zooming is switched to manual zooming, processing may be returned to Step S101again or returned as appropriate to Step S102, S105, or S108.

FIG. 7is a flowchart illustrating processing after the zoom operation function or the automatic focusing area (AF frame) selection function is assigned to the zoom electric operation unit18in Step S103illustrated inFIG. 6. In Step S201, when the automatic focusing area movement function is assigned to the zoom electric operation unit18, processing goes to Step S202. In Step S202, automatic focusing areas are displayed in a reference automatic focusing position and on closest two objects located on the near and far sides of the reference automatic focusing position. Then, whether or not the zoom electric operation unit18is operated is determined in Step S203. When the zoom electric operation unit18is operated, processing goes to Step S204. When the zoom electric operation unit18is not operated, processing goes to Step S207described later.

When the zoom electric operation unit18is operated, whether the operation direction of the zoom electric operation unit18is the T-direction (telephoto direction) or the W-direction (wide-angle direction) is determined in Step S204. When the zoom electric operation unit18is operated in the T-direction, processing goes to Step S205, and hence the automatic focusing area is moved in a depth direction, that is, a rear focus direction which is a direction away from the camera and lens. When the zoom electric operation unit18is operated in the W-direction, processing goes to Step S206, and hence the automatic focusing area is moved in a front direction, that is, a front focus direction which is a direction approaching the camera and lens. Note that the T-direction and the W-direction may be reversed to each other.

Then, when it is determined in Step S207that a desired automatic focusing (AF) condition is achieved by the photographer, processing goes to Step S208. With respect to whether or not the desired automatic focus condition is achieved in Step S207, when a time period during which the zoom electric operation unit18is not operated exceeds a predetermined time, it may be determined that the desired automatic focusing condition is achieved. The determination may be made by another method. The achievement of the desired automatic focus condition indicates not that the focus lens unit3is actually moved for focusing, but that a focusing area intended by the photographer corresponds to the automatic focusing area (AF frame) displayed on a display surface. In other words, in Step S207, the focus state of the automatic focusing area for actual focusing is determined. Even when the focus lens unit3is moved for focusing operation every time the automatic focusing area is moved in Step S205or Step206, there is no problem.

Next, in Step S208, the focus lens unit3is moved to focus on an object in the automatic focusing area to perform focusing operation.

When it is determined in Step S201that the zoom operation function is assigned to the zoom electric operation unit18, whether or not the zoom electric operation unit18is operated is determined in Step S209. When it is determined in Step S209that the zoom electric operation unit18is operated, processing goes to Step S210and the normal zoom operation is performed.

When a setting capable of continuously moving the automatic focusing area in a single direction in a case where the zoom electric operation unit18continues to be pressed in the direction for a long time is stored in advance in the control circuit10, usability is further improved. A moving speed of the automatic focusing area which is continuously moved as described above, and an operation time of the zoom electric operation unit18in the single direction, which is required to realize the continuous movement, that is, the amount of press of the zoom electric operation unit18, may be arbitrarily adjusted and changed by the photographer using the setting unit19.

When there is only a single object within the viewfinder, the control circuit10recognizes object information in advance by ranging based on the phase difference method as described above. Front focus information and rear focus information with respect to a reference object are not displayed on the viewfinder. Even when the zoom electric operation unit18to which the automatic focusing area movement function is assigned is operated, the automatic focusing area is not moved.

When the automatic focusing area movement function is assigned to the zoom electric operation unit18as described above, the automatic focusing area may be moved without the requirement of specific parts and the disruption of a normal image taking style of the photographer. Therefore, the convenience of shooting and the degree of freedom thereof are improved.

FIG. 8is a block circuit structural diagram illustrating an image pickup apparatus according to Embodiment 2. The actuator gear13and the zoom operation ring15can be switched by an electromagnetic clutch31. Embodiment 1 describes an example of the lens apparatus of a type for selectably switching between the electric zooming and the manual zooming using the clutch by the photographer. However, the present invention may be also applied to the lens main body1of a type for seamlessly switching between the electric zooming and the manual zooming using the electromagnetic clutch31provided in the drive unit2.

In such a case, for limited use during the manual zooming, the lens apparatus is provided with a zoom drive switch unit32for switching between the validity and invalidity of operation of the zoom electric operation unit18. When the zoom drive switch unit32is in an invalid mode, the automatic focusing area movement function is assigned to the operation of the zoom electric operation unit18as described above.

The present invention is based on the automatic focusing lens using the phase difference method. However, the present invention may be applied to an automatic focusing lens using a TV-automatic focusing method. This case requires that, before shooting, the focus lens unit1is driven once over the entire region between a close end and an infinite end and a contrast peak value of each of objects within the viewfinder is stored to calculate a focusing length.

According to the image pickup apparatus in each of the embodiments, the automatic focusing area may be selected using the existing operation member without providing specific members. Therefore, the convenience of the focus operation may be improved without an increase in the number of parts and a reduction in the degree of freedom of image taking by a photographer.

This application claims the benefit of Japanese Patent Application No. 2008-267492, field Oct. 16, 2008, which is hereby incorporated by reference herein in its entirety.