JP6458336B2 - Interchangeable lens and camera system - Google Patents

Description

  The present invention relates to an interchangeable lens such as a digital single lens reflex camera and a camera system including the interchangeable lens.

  2. Description of the Related Art Image pickup apparatuses that drive and control a plurality of focus lenses independently in the optical axis direction for focus adjustment are known (see, for example, Patent Documents 1 and 2).

  Of the multiple focus lenses, the main focus lens is the main focus lens, and the other focus lenses are sub-focus lenses. Conventionally, even if multiple focus lenses can be driven independently, focus drive The position of the subfocus lens at the time of completion is uniquely determined. For example, in Patent Document 1, the wobbling lens is a sub-focus lens, but is constant at the reference position at the end of focusing drive. In Patent Document 2, the sub-focus lens is temporarily deviated from the tracking position during the focusing operation. At the final focusing position, the sub-focus lens is determined from the main focus lens position. Positioned.

Japanese Patent No. 4437244 Japanese Patent No. 4820460

  If the camera body is equipped with a so-called phase difference focus detection device, the defocus amount on the imaging surface is detected, converted into the focus lens drive amount, and used as a drive command for focus adjustment. It is common to instruct an interchangeable lens. Conventionally, even when the driving amount for focus adjustment is small, the main focus lens, which is heavy, is moved and focused, so it takes time to move the main focus lens, and quick focusing There is a problem that it cannot be adjusted.

  The present invention has been made in view of such a situation, and an object thereof is to provide an interchangeable lens capable of driving a suitable focus lens, and a camera system including the interchangeable lens.

The present invention solves the above problems by the following means. That is, the invention of claim 1 is directed to an imaging optical system including first and second focus lenses movable in the optical axis direction, a communication unit capable of communicating with a camera having an imaging unit that images a subject, and the communication It received from the camera through the part, based on an image by the imaging optical system and the information for focusing on the imaging unit, and the position of the first and second focus lens, by the imaging optical system A control unit for controlling respective positions of the first and second focus lenses by determining respective movement amounts of the first and second focus lenses for focusing an image on the imaging unit; And a display unit that displays a shooting distance to the subject based on the positions of the first and second focus lenses.

Invention of Claim 2 is the interchangeable lens of Claim 1, Comprising: The said display part is the said 1st controlled by the said control part to the position which focuses the image by the said imaging optical system on the said imaging part And an interchangeable lens that displays the shooting distance to the subject based on the position of the second focus lens.

A third aspect of the present invention is the interchangeable lens according to the first or second aspect, wherein the display unit sets the first and second focus lenses to 1 from the positions of the first and second focus lenses. This is an interchangeable lens that displays the shooting distance based on the position when two focus lenses are used.

The invention according to claim 4, each exchangeable lens according to any one of claims 1 to 3, wherein the control unit, the second focus lens only the image the image formed by the imaging optical system by moving the parts in-focus if possible, an interchangeable lens that controls only the position of the second focus lens.
A fifth aspect of the present invention is the interchangeable lens according to any one of the first to fourth aspects, wherein the control unit controls information on each position of the first and second focus lenses. Is stored in the storage unit, and the storage unit includes an imaging distance based on the positions of the first and second focus lenses and a movement of the image plane in the imaging unit with respect to a movement amount of the first focus lens. A coefficient representing a ratio of the amount and a coefficient representing a ratio of a moving amount of the second focus lens corresponding to a moving amount of the image plane in the imaging unit with respect to a moving amount of the first focus lens; Is an interchangeable lens.
A sixth aspect of the invention is the interchangeable lens according to any one of the first to fifth aspects, wherein the second focus lens is lighter or faster than the first focus lens. It is.
A seventh aspect of the invention is a camera system including the interchangeable lens according to any one of the first to sixth aspects.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the interchangeable lens which can drive a suitable focus lens, and the camera system provided with this interchangeable lens.

It is a block diagram which shows the structure of the interchangeable lens which concerns on embodiment. It is an example of a focus lens drive information table. It is a typical top view of the camera concerning an embodiment. It is a flowchart which shows drive control of the focus lens which concerns on embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an interchangeable lens according to the present embodiment.

  The interchangeable lens 60 is mechanically coupled to the body portion 50 of the camera system 1 (hereinafter abbreviated as “camera 1”) via a predetermined mounting mechanism. The interchangeable lens 60 and the body unit 50 can communicate data via an electrical contact 170. An imaging optical system 110 is disposed in the lens barrel 100 of the interchangeable lens 60. The imaging optical system 110 is composed of a plurality of lens groups, and includes a first focus lens 111 and a second focus lens 112 for performing focus adjustment. The second focus lens 112 is disposed closer to the image side than the first focus lens 111. Light from a subject (not shown) is imaged on the image sensor 180 disposed in the body unit 50 via the imaging optical system 110. The image sensor 180 converts the formed subject image into an electrical signal. The subject image converted into the electrical signal is subjected to predetermined image processing by a known method in an image processing unit (not shown) on the body unit 50 side.

  The first focus lens 111 is a main focus lens capable of performing focus adjustment in the entire focusing range, and the second focus lens 112 is a sub-focus lens having a narrower focus adjustment range than the first focus lens 111. The first focus lens 111 and the second focus lens 112 can be driven independently. The second focus lens 112 is lighter than the first focus lens 111 and can be driven at high speed. The first focus lens 111 is driven in the optical axis direction by the first focus lens driving unit 121. The first focus lens drive unit 121 includes a drive motor (not shown) and a drive circuit (not shown). The second focus lens 112 is driven in the optical axis direction by the second focus lens driving unit 122. The second focus lens drive unit 122 includes a drive motor (not shown) and a drive circuit (not shown).

  The lens barrel 100 is provided with a first focus lens position detector 131 and a second focus lens position detector 132. The first focus lens position detector 131 detects the position of the first focus lens 111 in the optical axis direction. The second focus lens position detector 132 detects the position of the second focus lens 112 in the optical axis direction. The first and second focus lens position detectors 131 and 132 use, for example, a magnetic sensor that outputs a two-phase sinusoidal signal or an encoder, and the first focus lens 111 and the second focus lens 112. Is calculated. Since such a position detection device is conventionally known, detailed description thereof is omitted here. Position information of the first and second focus lenses 111 and 112 detected by the first and second focus lens position detection units 131 and 132 is taken into the lens control unit 150 and used for various arithmetic processes described later.

  The lens control unit 150 includes a communication control unit 157, a nonvolatile memory 156, a lens drive amount calculation unit 153, a first focus lens drive control unit 151, a second focus lens drive control unit 152, and a combination position calculation unit. 154 and a distance calculation unit 155. The control program operated by the lens control unit 150 includes interface control with the body unit 50, focus lens drive control, first focus lens drive control, second focus lens drive control, combination position calculation, and shooting distance calculation.

  The communication control unit 157 controls communication of data notified from the interchangeable lens 60 side to the body unit 50 side and data notified from the body unit 50 side to the interchangeable lens 60 side.

  The nonvolatile memory 156 stores various data for focus lens drive control. Various data includes the following three pieces of information. The first information is a shooting distance corresponding to the position of the first focus lens 111. Note that the position of the first focus lens 111 stored in the nonvolatile memory 156 is actually the position of the first focus lens 111 and the second focus lens regarded as the position of the first focus lens 111 as described later. This is the combined focus lens position with the focus lens 112. The second information is a coefficient representing the ratio of the movement amount of the image plane to the movement amount of the first focus lens 111, that is, the image plane movement coefficient K1 of the first focus lens 111. The third information is a coefficient α representing the ratio of the movement amount of the second focus lens 112 to the movement amount of the first focus lens 111.

Here, the coefficient α will be described. In the case where the moving distance of the first focus lens 111 is realized by only the movement of the first focus lens 111 and the moving distance of the first focus lens 111 is L1, and the same movement amount of the image plane is realized only by the movement of the second focus lens 112. The moving distance of the second focus lens 112 is L2. Further, when a coefficient representing the ratio of the movement amount of the image plane to the movement amount of the second focus lens 112, that is, the image plane movement coefficient of the second focus lens 112 is K2, the following expression (1) is established.
(1) L1 × K1 = L2 × K2
Since the coefficient α is a ratio of L2 to L1, the coefficient α can be obtained by the following equation (2).
(2) α = L2 / L1 = K1 / K2
That is, α can be obtained from the image plane movement coefficients of the first and second focus lenses 111 and 112, respectively.

  Various data including these three pieces of information are stored in the nonvolatile memory 156 as table information. FIG. 2 is an example of a focus lens drive information table. The data stored as such table information is referred to in various arithmetic processes executed by the lens control unit 150. Information on the image plane movement coefficient K1 of the first focus lens 111 is transferred to the body unit 50 when the camera 1 is turned on.

  The body portion 50 of the camera 1 is equipped with a focus detection device (not shown) using a phase difference detection method. In addition, since the focus detection apparatus by a phase difference detection system is conventionally well-known, detailed description is abbreviate | omitted here. The focus detection device detects the defocus amount up to the in-focus position, that is, the image plane movement amount. The detected defocus amount is converted into the movement amount of the focus lens using the image plane movement coefficient information acquired in advance from the table information (see FIG. 2) of the lens barrel 100 by the control unit 190 on the body unit 50 side. Is done. At this time, the control unit 190 on the body unit 50 side does not recognize that the interchangeable lens 60 includes two focus lenses that can be independently driven. Therefore, the focus lens of the interchangeable lens 60 includes one lens group. The amount of movement of the focus lens is calculated as follows. The movement amount of the focus lens as one lens group calculated by the control unit 190 on the body unit 50 side is instructed to the interchangeable lens 60 side during focusing driving.

  The lens drive amount calculation unit 153 includes a focus lens drive amount instructed from the body unit 50, table information stored in the nonvolatile memory 156, and current position information of the first and second focus lenses 111 and 112. Based on the above, the driving amount for focusing the first and second focus lenses 111 and 112 is determined. The drive amounts of the first and second focus lenses 111 and 112 are notified to the first focus lens drive control unit 151 and the second focus lens drive control unit 152, respectively. Details of processing in the lens driving amount calculation unit 153 will be described later.

  In the first focus lens drive control unit 151, the current position of the first focus lens 111 detected by the first focus lens position detection unit 131 and the drive target of the first focus lens 111 determined by the lens drive amount calculation unit 153. An arithmetic process for drive control is performed based on the position. The first focus lens driving unit 121 moves the first focus lens 111 in the optical axis direction according to the calculation result.

  In the second focus lens drive controller 152, the current position of the second focus lens 112 detected by the second focus lens position detector 132 and the drive target of the second focus lens 112 determined by the lens drive amount calculator 153. An arithmetic process for drive control is performed based on the position. The second focus lens driving unit 122 moves the second focus lens 112 in the optical axis direction according to the calculation result.

  The combination position calculation unit 154 regards the first and second focus lenses 111 and 112 as a focus lens including one lens group, and regards the first and second focus lenses 111 and 112 as the one from the position information of each of the first and second focus lenses 111 and 112. Calculate the position of the focus lens. In the present embodiment, the position of the focus lens regarded as the one is regarded as the position of the first focus lens 111. The position of the first focus lens stored in the information table (see FIG. 2) stored in the nonvolatile memory 156 is actually the combined focus lens position regarded as the position of the first focus lens 111. The combination focus lens position calculated by the combination position calculation unit 154 is notified to the body unit 50.

  The distance calculation unit 155 calculates the actual shooting distance from the combined focus lens position obtained by the combination position calculation unit 154. That is, the distance from the imaging surface of the image sensor 180 to the subject is calculated. The obtained shooting distance is displayed on the distance index display unit 160.

  FIG. 3 is a schematic plan view of the camera 1. The distance index display unit 160 is provided on the upper outer peripheral surface of the lens barrel 100 as shown in FIG. The distance index display unit 160 is a liquid crystal display unit, and the distance is digitally displayed.

  Next, the flow of processing in the lens drive amount calculation unit 153 when a focus drive command is received from the body unit 50 will be described with reference to the flowchart shown in FIG.

FIG. 4 is a flowchart showing focus lens drive control of the interchangeable lens 60 according to this embodiment. When the lens driving amount calculation unit 153 receives a focus lens driving command for focusing operation from the body unit 50 via the communication control unit 157, the lens driving amount calculation unit 153 sets the instructed focus lens driving amount Ddef to the following equation (3). Is converted into the drive amount MD2 of the second focus lens 112 (step S201). As described above, since the body unit 50 side does not recognize that the interchangeable lens 60 includes two independent focus lenses, the focus calculated by assuming that the focus lens of the interchangeable lens 60 is composed of one lens group. The lens driving amount is instructed. That is, the driving amount Ddef of the focus lens instructed from the body unit 50 is the driving amount of the focus lens as the one lens group when the focus lens of the imaging optical system 110 is assumed to be composed of one lens group. .
(3) MD2 = Ddef × α
In Expression (3), α is determined from the table information stored in the nonvolatile memory 156 based on the current position of the first focus lens 111.

Next, the lens drive amount calculation unit 153 calculates the drive target position P2 of the second focus lens 112 when the focus adjustment amount corresponding to Ddef is adjusted only by the second focus lens 112 (step S202). P2 is a value obtained by adding MD2 to the current position P2cur of the second focus lens 112, and is represented by Expression (4).
(4) P2 = P2cur + MD2

  Next, the lens drive amount calculation unit 153 determines whether P2 is within the drive range of the second focus lens 112 (step S203). If P2 is within the drive range of the second focus lens 112, the image plane movement amount corresponding to the focus lens drive amount instructed by the body unit 50 can be realized only by the movement of the second focus lens 112. In this case, the lens drive amount calculation unit 153 instructs the second focus lens drive control unit 152 to drive the second focus lens 112 using P2 obtained by Expression (4) as a target position (step S204). After the driving of the second focus lens 112 is started, the process proceeds to step S208.

On the other hand, when P2 exceeds the driving range of the second focus lens 112, the first focus lens 111 needs to be driven. In this case, the lens drive amount calculation unit 153 obtains the drive target position of the first focus lens 111 from the following equation (5) (step S205).
(5) P1 = P1cur + Ddef−D2ofs
However,
P1cur: current position of the first focus lens 111 Ddef: drive amount of the focus lens instructed by the body unit 50 D2ofs: conversion of the shift amount of the second focus lens 112 from the reference position into a movement amount of the first focus lens 111 In addition, D2ofs is calculated | required by following Formula (6).
(6) D2ofs = (P2cur−P2ref) / α
However,
P2ref: Reference position of the second focus lens 112 Here, in this embodiment, the reference position of the second focus lens 112 is the center position of the driving range of the second focus lens 112 regardless of the shooting distance.

  When the target position P1 of the first focus lens 111 is obtained in step S205, the lens drive amount calculation unit 153 instructs the first focus lens drive control unit 151 to start driving the first focus lens 111 (step S206). In addition, the second focus lens drive control unit 152 is also instructed to start driving the second focus lens 112 (step S207). The target position of the second focus lens 112 in step S207 is set to the reference position P2ref of the second focus lens 112. When the second focus lens 112 is already positioned at the reference position P2ref, only the first focus lens 111 is driven. Even when the second focus lens 112 reaches the reference position P2ref before the first focus lens 111 reaches the target position P1, only the first focus lens 111 is driven thereafter. That is, the image plane movement amount corresponding to the focus lens drive amount instructed by the body unit 50 is realized only by the movement of the first focus lens 111 or the movement of the first focus lens 111 and the second focus lens 112. Become. After the driving of the first and second focus lenses 111 and 112 is started, the following processes of step S208 and step S209 are repeatedly executed until the driving is ended.

In step S208, based on the current position of the first focus lens 111 and the current position of the second focus lens 112, the combination position calculation unit 154 calculates the combination focus lens position Pcf by the following equation (7). The combined focus lens position Pcf is the position of the focus lens regarded as one when the first and second focus lenses 111 and 112 are regarded as a focus lens composed of one lens group. In the present embodiment, the position of the focus lens regarded as the one is regarded as the position of the first focus lens 111.
(7) Pcf = P1cur + D2ofs
However,
P1cur: Current position of the first focus lens 111 D2ofs: Value obtained by converting the amount of deviation of the second focus lens 112 from the reference position into the amount of movement of the first focus lens 111

  The combination position calculation unit 154 uses the combination focus lens position Pcf obtained by Expression (7) at the end of driving of the first and second focus lenses 111 and 112 as focus lens position information via the communication control unit 170. Notify the control unit 190 on the body unit 50 side. Based on the combination focus lens position Pcf notified at this time, the control unit 190 of the body unit 50 calculates the focus lens drive amount Ddef at the time of the next focus drive command. Further, the combined focus lens position Pcf is also notified to the control unit 190 on the body unit 50 side when the camera 1 is turned on, and based on this, the control unit 190 is the focus lens at the time of the first focusing drive command after the power is turned on. The driving amount Ddef is calculated.

  The combined focus lens position Pcf obtained by the combination position calculation unit 154 is further input to the distance calculation unit 155, and converted into a shooting distance by the distance calculation unit 155 (step S209). Specifically, based on the relationship between the first focus lens position and the shooting distance stored in advance in the information table (see FIG. 2) stored in the non-volatile memory 156, the input combination focus lens position Pcf Calculate the corresponding shooting distance. In other words, interpolation processing of data relating to the shooting distance in the information table stored in advance is executed. The shooting distance thus obtained is displayed on the distance index display unit 160.

  Note that the reason why the shooting distance is obtained in this way in the present embodiment is as follows. In other words, if there is only one focus lens, a mechanism such as a cam ring or the like provided with a distance scale corresponding to the movement of the focus lens can be rotated to mechanically instruct the distance scale. In the embodiment, only the first focus lens moves, only the second focus lens moves, or the first focus lens 111 and the second focus lens 112 move together. This is because the mechanism cannot be interlocked with the movement of the focus lenses 111 and 112.

  After confirming that the driving of the first focus lens 111 and the second focus lens 112 has been completed, the lens drive amount calculation unit 153 ends the focus lens focusing drive process (step S210).

  Thus, according to the present embodiment, when the amount of drive to the in-focus position is small and focusing is possible only by driving the second focus lens 112, only the second focus lens 112 capable of high-speed operation is driven, In other cases, focus adjustment is performed by driving only the first focus lens or the first focus lens 111 and the second focus lens 112 together. For this reason, in-focus driving can be performed in the shortest time. Further, by notifying the body portion 50 of the camera 1 of the combined focus lens position information, the focus drive can be performed without considering the presence of the second focus lens 112. For this reason, it is possible to achieve optimum focus driving according to the situation while maintaining high compatibility with the conventional focus lens drive control. That is, since the compatibility of the command interface between the camera body part and the interchangeable lens 60 in the focus adjustment operation can be ensured, the autofocus operation can be performed even when the camera is mounted on a camera body that has already been released.

  Furthermore, since the shooting distance information is displayed on the distance index display unit 160, it is possible to ensure the consistency between the actual in-focus position and the shooting distance information displayed on the distance index display unit 160.

  In the present embodiment, the focus lens drive control by the phase difference detection method is shown. However, in the contrast detection method, the second focus lens 112 is driven as a wobbling lens to adjust the focus using a known technique. Is possible. Further, the shooting distance information obtained on the basis of the position of the combined focus lens may be appropriately notified to the body 50 of the camera, so that the shooting distance information may be displayed on the finder. You may let them.

  Although the description of each embodiment of the present invention is finished as described above, the configuration of the present invention is not limited to the above embodiment, and can be changed as appropriate.

DESCRIPTION OF SYMBOLS 1 Interchangeable lens 50 Camera body 60 Interchangeable lens 100 Lens barrel 110 Imaging optical system 111 1st focus lens 112 2nd focus lens 121 1st focus lens drive part 122 2nd focus lens drive part 131 1st focus lens position detection part 132 Second focus lens position detection unit 150 Lens control unit 151 First focus lens drive control unit 152 Second focus lens drive control unit 153 Lens drive amount calculation unit 154 Combination position calculation unit 155 Distance calculation unit 156 Non-volatile memory 157 Communication control unit 160 Distance index display unit 170 Electrical contact 180 Image sensor 190 Control unit on the body side

Claims (7)

An imaging optical system including first and second focus lenses movable in the optical axis direction;
A communication unit capable of communicating with a camera having an imaging unit for imaging a subject;
Based on the information received from the camera via the communication unit for focusing the image by the imaging optical system on the imaging unit, and the positions of the first and second focus lenses , the imaging optical A control unit for determining respective movement amounts of the first and second focus lenses for focusing the image by the system on the imaging unit, and controlling the positions of the first and second focus lenses;
An interchangeable lens comprising: a display unit configured to display a shooting distance to the subject based on positions of the first and second focus lenses. The interchangeable lens according to claim 1,
The display unit is configured to calculate a shooting distance to the subject based on the positions of the first and second focus lenses controlled by the control unit at a position where the image by the imaging optical system is focused on the imaging unit. Interchangeable lens to display. The interchangeable lens according to claim 1 or 2,
The display unit is an interchangeable lens that displays the photographing distance based on a position when the first and second focus lenses are used as one focus lens from the positions of the first and second focus lenses. The interchangeable lens according to any one of claims 1 to 3 ,
Wherein the control unit, the second focus lens only the imaging optical system by moving the focus if an image on the imaging unit by the interchangeable lens to control only the position of the second focus lens. The interchangeable lens according to any one of claims 1 to 4 ,
A storage unit storing information used when the control unit controls the respective positions of the first and second focus lenses;
The storage unit includes a photographing distance based on the positions of the first and second focus lenses, and a coefficient representing a ratio of a moving amount of the image plane in the imaging unit to a moving amount of the first focus lens; An interchangeable lens storing a coefficient representing a ratio of a movement amount of the second focus lens corresponding to a movement amount of the image plane in the imaging unit with respect to a movement amount of the first focus lens. The interchangeable lens according to any one of claims 1 to 5 ,
The second focus lens is an interchangeable lens that is lighter or faster movable than the first focus lens. A camera system comprising the interchangeable lens according to any one of claims 1 to 6 .

Images