WO2009139188A1 - Image pickup system and camera body and replaceable lens - Google Patents

Abstract

An image pickup system includes a replaceable lens and camera body. The replaceable lens comprises a movable member (such as for example a lens or diaphragm), drive means for changing the state of the movable member (such as for example the position or degree of opening thereof) by driving the movable member, lens control means that controls the drive means, and holding means that holds information relating to backlash of the drive means. The camera body comprises body control means that controls the operation of the replaceable lens and the camera body. The body control means transmits control information for controlling the drive means to the lens control means. The body control means acquires information relating to backlash from the replaceable lens and, when controlling the state of the movable member to a target state, changes over the method of control of the direction in which the state of the movable member is changed, in accordance with this acquired information.

Description

Imaging system, camera body, interchangeable lens

The present invention relates to an imaging system including a camera body and an interchangeable lens, and a camera body and an interchangeable lens that can be used in the imaging system.

In an imaging system composed of a camera body and an interchangeable lens, a target position of the focus lens of the interchangeable lens is obtained based on focusing information detected by contrast detection or phase difference detection, and the focus lens is driven to the target position. It is designed to be driven through.

Here, such a driving means generally has a backlash. In general, the backlash is a gap that is intentionally provided in the direction of movement in a machine element that moves by fitting with each other, such as a feed screw and a gear used in a machine. This clearance allows the screws and gears to move freely. However, this backlash may cause a shift in the amount of movement when a machine element that has been driven in a certain direction is driven in the opposite direction. For this reason, even if the focus lens is focused, the position of the focus lens may deviate from the actual focus position by the amount of backlash.

There is a technique disclosed in Patent Document 1 as a technique capable of coping with this problem. In this technique, the interchangeable lens being used is provided with a storage means for storing a deviation with respect to the backlash amount of the reference interchangeable lens, and the camera body reads the deviation via the communication means, Based on this, the backlash amount of the interchangeable lens is calculated, the lens movement amount obtained by correcting the backlash amount is calculated, and the driving means is controlled based on the movement amount. Thus, since the backlash amount is taken into account when calculating the lens movement amount, the focusing accuracy is improved.

Japanese Patent Application Laid-Open No. 61-017111

In the technique described in Patent Document 1, when the focus lens is moved to the target position, the camera body reads a deviation with respect to the backlash amount of the reference interchangeable lens through the communication unit, and the exchange is performed based on the deviation. A backlash amount of the lens is calculated, and a lens movement amount obtained by correcting the backlash amount is calculated. For this reason, there is a problem that the time required for the focusing operation becomes long.

Incidentally, there are various types of driving means, and the backlash amount may be small depending on the structure. When the backlash amount is small, sufficient focusing accuracy may be obtained without performing correction as in Patent Document 1. That is, in such a case, the time required for the focusing operation is unnecessarily long.

Note that these problems are not limited to the focus lens, and can also be said when the aperture means for changing the area of the opening is controlled to the target opening degree via the drive means.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging system capable of realizing accurate driving of a driving unit of a movable member (a focus lens or a diaphragm) having backlash. And

In a first aspect, an imaging system including an interchangeable lens and a camera body is provided. The interchangeable lens includes a movable member (for example, a lens and a diaphragm), a driving unit that drives the movable member to change the state (for example, position and opening) of the movable member, a lens control unit that controls the driving unit, Holding means for holding information relating to backlash of the driving means. The camera body includes body control means for controlling operations of the camera body and the interchangeable lens. The main body control means transmits control information for controlling the driving means to the lens control means. Further, the main body control means acquires information on the backlash held by the holding means from the interchangeable lens, and changes the state of the movable member when controlling the state of the movable member to the target state according to the acquired information. Switch the control method of the direction to be performed. With this configuration, the main body control unit can instruct an optimal control method for the interchangeable lens based on information related to backlash of the drive unit. As a result, the influence of backlash can be eliminated while enabling the movable member to be driven at high speed.

In the second aspect, an interchangeable lens that can be attached to the camera body is provided. The interchangeable lens holds binary information about a movable member, a driving unit that drives the movable member to change the state of the movable member, a lens control unit that controls the driving unit, and backlash of the driving unit. Holding means.

In a third aspect, there is provided a camera body to which an interchangeable lens including a movable member and a driving unit that drives the movable member to change the state of the movable member can be mounted. The camera body includes body control means for controlling operations of the camera body and the interchangeable lens. The main body control means transmits control information for controlling the driving means to the interchangeable lens. The main body control unit acquires information about backlash of the driving unit from the interchangeable lens, and changes the state of the movable member when controlling the state of the movable member to the target state according to the acquired information. Switch the control method.

According to the present invention, the camera body recognizes information related to the backlash of the drive unit of the movable member in the interchangeable lens, and appropriately switches the drive method of the drive unit according to the information related to the backlash. Thereby, the imaging system which can implement | achieve the drive with a sufficient precision of the drive part which has a backlash can be provided.

Configuration diagram of imaging system in embodiment (optical viewfinder mode) Configuration diagram of imaging system in embodiment (live view mode) The figure which shows the structural example of the drive means with a small backlash amount. The figure which shows the structural example of the drive means with a large backlash amount The figure which shows the structural example of the drive means from which the amount of backlashes changes. The figure which shows signal transmission / reception of the imaging system in embodiment The figure explaining the operation of the focus lens in the focusing operation by the phase difference detection method The figure explaining the operation of the focus lens in the focusing operation by the hill-climbing method The figure which shows an example of the simple transmission means of the information regarding a backlash The figure explaining the operation of the focus lens by wobbling

(Embodiment 1)
1. Configuration FIG. 1 and FIG. 2 are configuration diagrams of an imaging system according to an embodiment. The imaging system includes an interchangeable lens 100 and a camera body 200, and the interchangeable lens 100 can be attached to and detached from a predetermined position on the camera body 200.

1-1. Camera body The main mirror 207 is a half mirror, and the sub mirror 208 is a mirror. The state of FIG. 1 and the state of FIG. 2 are changed.

In the state of FIG. 1, the main mirror 207 reflects part of the subject light incident from the interchangeable lens 100 and transmits part of it. The subject light reflected by the main mirror 207 forms an image on the focusing screen 206. The photographer can visually recognize the subject image formed on the focusing screen 206 through the eyepiece lens 205 and the pentaprism 204. This state (the state shown in FIG. 1) is called an optical finder mode. On the other hand, the subject light transmitted through the main mirror 207 is reflected by the sub-mirror 208 and enters the focus detection unit 211. The focus detection unit 211 is composed of a line sensor. The main body control unit 203 can recognize the in-focus state from the output of the focus detection unit 211. The focusing method that automatically focuses using the output of the focus detection unit 211 is generally called a phase difference detection method. In this state (the state shown in FIG. 1), since the subject light does not reach the image sensor 202, the shutter 209 is closed. The image sensor 202 is configured by a CCD image sensor or a CMOS image sensor.

In the state of FIG. 2, the main mirror 207 and the sub mirror 208 are retracted from the optical path. The shutter 209 is in an open state. The subject light incident from the interchangeable lens 100 enters the image sensor 202 as it is. The image signal output from the image sensor 202 is displayed on the image display unit 210 after being converted into image data by the main body control means 203. The image display unit 210 includes a liquid crystal display or an organic EL display. The photographer can view the subject image with the image display unit 210. This state (the state of FIG. 2) is called a live view mode. The main body control unit 203 can recognize the in-focus state from the contrast of the image data based on the image signal output from the image sensor 202. A focusing method that automatically focuses using the output of the image sensor 202 is generally called a hill-climbing method (or contrast AF method).

The attachment detection means 212 can detect the attachment of the interchangeable lens 100 to the camera body 200. The attachment detection means 212 can be constituted by a mechanical switch or the like. The main body control unit 203 can recognize the mounting of the interchangeable lens 100 by monitoring the state of the mounting detection unit 212. Note that the attachment detection means 212 is not an essential component of the present invention. The main body control unit 203 may detect attachment of the interchangeable lens 100 to the camera main body 200 by communicating with the lens control unit 105 via the second communication unit 201 and the first communication unit 106.

In addition to the functions described above, the main body control means 203 can convert the image signal output from the image sensor 202 into image data and record it on a recording medium (not shown). The main body control means 203 may be a single LSI or a plurality of LSIs. The second communication unit 201 may be a dedicated LSI, or the main body control unit 203 may include the function. The camera body 200 is equipped with a release button that the photographer instructs to shoot, a mode dial that switches various modes of the camera body 200, a battery that supplies power to each part of the camera body 200 and the interchangeable lens 100, a power circuit, and the like. It is omitted in FIGS.

1-2. Interchangeable Lens The subject light transmitted through the objective lens 101 enters the zoom lens 102. The zoom lens 102 can change the magnification of the subject image by moving back and forth on the optical axis L. The zoom lens 102 advances and retreats on the optical axis L when a photographer operates a zoom ring (not shown) provided on the interchangeable lens 100. The aperture unit 103 limits the amount of subject light. In the aperture unit 103, the area of the opening changes when the photographer operates an aperture ring (not shown) provided in the interchangeable lens 100. The focus lens 104 advances and retreats on the optical axis L, so that the subject light is focused on the focusing screen 206, the focus detection unit 211 (in the case of the optical viewfinder mode in FIG. 1) or the image sensor 202 (in the case of the live view mode in FIG. 2). To form an image. The driving unit 107 is a DC motor, a stepping motor, an ultrasonic motor, or the like for moving the focus lens 104 back and forth on the optical axis L. The lens control unit 105 controls the driving unit 107 based on the control information obtained from the main body control unit 203 via the first communication unit 106 and the second communication unit 201. Information unique to the interchangeable lens 100 is stored in the storage unit 108. The lens control unit 105 can transmit information unique to the interchangeable lens 100 stored in the storage unit 108 to the main body control unit 203 via the first communication unit 106 and the second communication unit 201.

Note that the lens control means 105 may be a single LSI or a plurality of LSIs. The first communication unit 106 may be a dedicated LSI, or the lens control unit 105 may include the function. The storage unit 108 may be a single storage element such as a flash memory, or the lens control unit 105 may include its function.

In addition to the above-described configuration, the zoom lens 102 converts a zoom ring operation by a photographer into an electrical signal, and a driving unit (not shown) moves the zoom lens 102 forward and backward on the optical axis L based on the converted electrical signal. It is good also as a structure driven by. In addition, an operation unit is provided in the camera main body 200, and an operation of the operation unit by the photographer is converted into an electric signal. The driving unit (not shown) that controls the driving of the zoom lens 102 on the optical axis L may be controlled based on the electrical signal transmitted to the control unit 105 and transmitted by the lens control unit 105.

In addition to the configuration described above, the aperture unit 103 is provided with an operation unit in the camera main body 200 to convert the operation of the operation unit by the photographer into an electrical signal. Drive means (not shown) that changes the area of the aperture of the aperture unit 103 based on the transmitted electrical signal. It is good also as a structure to control. Further, brightness information (FIG. 1) obtained from the output of a photometric sensor (not shown) provided in the camera body 200 (FIG. 1, in the case of the optical viewfinder mode) or image data based on the image signal output from the image sensor 202. 2 and the live view mode), the main body control means 203 may automatically determine the aperture value of the aperture unit 103. The main body control unit 203 transmits the control information of the aperture unit 103 to the lens control unit 105 via the second communication unit 201 and the first communication unit 106, and the lens control unit 105 transmits the transmitted aperture unit. Based on the control information 103, driving means (not shown) for changing the area of the opening of the aperture unit 103 is controlled.

1-3. Driving Unit FIG. 3 is a diagram showing a configuration example of the driving unit 107 having a small backlash amount. The focus lens 104 is supported on the drive shaft 305 by the focus lens frame 303 and on another support shaft 306 by another focus lens frame 304. The drive shaft 305 is threaded. One end of the drive shaft 305 is rotatably supported by the base 301, and the other end is fixed to the stepping motor 307. One end of the support shaft 306 is fixed to the base 301 and the other end is fixed to another base 302. The focus lens frame 303 is formed with a through hole in which a thread groove that matches the thread of the drive shaft 305 is formed. The focus lens frame 304 has a through hole through which the support shaft 306 is inserted. Therefore, when the stepping motor 307 rotates, the focus lens frame 303 advances and retreats on the drive shaft 305 in the optical axis L direction, and the focus lens frame 304 slides on the support shaft 306 in the optical axis L direction. In this way, the focus lens 104 can advance and retract on the optical axis L. In this configuration, the backlash exists between the screw thread of the drive shaft 305 and the screw groove of the focus lens frame 303, but is generally smaller than the backlash that exists between the gears.

FIG. 4 is a diagram showing a configuration example of the driving means 107 having a large backlash amount. 4A is a diagram of the driving unit 107 viewed from a direction perpendicular to the optical axis L, and FIG. 4B is a diagram of the driving unit 107 viewed from the optical axis L direction. In order to avoid complication of the drawing, the gear frame 325 is omitted in FIG. 4A, and the base 311 and the base 312 are omitted in FIG. 4B. Further, the first gear 319, the reduction gear (large) 320, the reduction gear (small) 321 and the final gear 322 are gears, but the description of the teeth is omitted in FIG.

The focus lens 104 is supported on the support shaft 316 by the focus lens frame 313 and on another support shaft 317 by another focus lens frame 314. A rack 315 is provided below the focus lens frame 314. One end of the support shaft 316 and the support shaft 317 is fixed to the base 311, and the other end is fixed to another base 312. The focus lens frames 313 and 314 are formed with through holes through which the support shafts 316 and 317 are inserted, respectively. A first gear 319 provided in the DC motor 318 is meshed with a reduction gear (large) 320. The DC motor 318 is fixed to the gear frame 325. The reduction gear (small) 321 and the reduction gear (large) 320 are integrally formed, and when the reduction gear (large) 320 rotates, the reduction gear (small) 321 also rotates. The reduction gear (large) 320 and the reduction gear (small) 321 are rotatably supported on the gear frame 325 by a rotation shaft 323. The reduction gear (small) 321 meshes with the final gear 322. The final stage gear 322 is rotatably supported on the gear frame 325 by the rotation shaft 324. The final gear 322 meshes with the rack 315. Accordingly, when the DC motor 318 rotates, the focus lens frame 314 advances and retreats on the support shaft 317 in the optical axis L direction, and the focus lens frame 313 slides on the support shaft 316 in the optical axis L direction. In this way, the focus lens 104 can advance and retract on the optical axis L. In this configuration, backlash exists between the first gear 319 and the reduction gear (large) 320, between the reduction gear (small) 321 and the final gear 322, and between the final gear 322 and the rack 315, respectively. The backlash amount of the entire driving means 107 is obtained by adding these backlash amounts. Therefore, the backlash amount of the driving means 107 according to FIG. 4 is considerably larger than the backlash amount of the driving means 107 according to FIG.

FIG. 5 is a diagram illustrating a configuration example of the driving unit 107 in which the backlash amount changes. FIG. 5A is an exploded perspective view of the driving unit 107, and FIG. 5B is a diagram showing a state where the focus lens frame 333 is at a position where the backlash amount is small. FIG. 5C is a diagram showing a state where the focus lens frame 333 is at a position where the backlash amount is large.

When the photographer operates the zoom ring or operates the operation unit of the camera body 200, the zoom lens 102 moves back and forth on the optical axis L, and the focal length of the interchangeable lens 100 changes. At this time, if there is no change in the position of the focus lens 104, even if the photographer is in focus before the operation of the zoom ring or the operation unit of the camera body 200, it is not in focus after these operations. It becomes a state. In order to prevent this, a focus tracking function is known that maintains the in-focus state by moving the focus lens 104 forward and backward along the optical axis L as the zoom lens 102 advances and retracts along the optical axis L. The focus tracking function can also be realized by a method of driving the focus lens 104 with a motor or the like. FIG. 5 shows an example in which the focus tracking function is configured by a first cam groove 334, a second cam groove 335, and a cam follower 336.

The fixed frame 332 is housed inside the zoom interlocking frame 331, and the focus lens frame 333 is housed inside the fixed frame 332, respectively. The first cam groove 334 and the second cam groove 335 are openings provided on the side surfaces of the zoom interlocking frame 331 and the fixed frame 332, respectively. When the focus lens frame 333 is housed inside the zoom interlocking frame 331 and the fixed frame 332, the cam follower 336 engages with both the first cam groove 334 and the second cam groove 335. The zoom interlocking frame 331 rotates with respect to the interchangeable lens 100 when the photographer operates the zoom ring or operates the operation unit of the camera body 200. The fixed frame 332 is fixed to the interchangeable lens 100. The focus lens frame 333 holds the focus lens 104 inside. Therefore, when the photographer operates the zoom ring or operates the operation unit of the camera body 200, the focus lens frame 333 holding the focus lens 104 advances and retreats on the optical axis L.

When the focus lens frame 333 is at the position shown in FIG. 5B, the play in the optical axis L direction with respect to the cam follower 336 at the overlapping portion of the first cam groove 334 and the second cam groove 335 is small. It can be said that the lens frame 333 is at a position where the backlash amount is small. On the other hand, when the focus lens frame 333 is in the position of FIG. 5C, the play in the optical axis L direction with respect to the cam follower 336 at the overlapping portion of the first cam groove 334 and the second cam groove 335 is large. It can be said that the focus lens frame 333 is at a position where the backlash amount is large. Although not shown, it can be said that the focus lens frame 333 is at a position where the backlash amount is large even when the focus lens frame 333 is at a position opposite to the position shown in FIG. Therefore, the backlash amount of the driving means 107 according to FIG. 5 varies depending on the position of the focus lens frame 333 in the optical axis L direction.

2. Operation Subsequently, the main body control unit 203 receives the information on the backlash stored in the storage unit 108 via the second communication unit 201 and the first communication unit 106, and responds to the received information on the backlash. The operation for determining the control method of the driving means 107 will be described.

2-1. Reception of Information Regarding Backlash FIG. 6 is a diagram illustrating signal transmission / reception of the imaging system according to the embodiment. When the photographer turns on the camera body 200 with the interchangeable lens 100 attached to the camera body 200, the body control unit 203 monitors the state of the attachment detection unit 212 and recognizes the attachment of the interchangeable lens 100. . The main body control unit 203 causes the power supply circuit (not shown) to supply power to the interchangeable lens 100 (S11). The main body control unit 203 requests lens authentication information of the interchangeable lens 100 from the lens control unit 105 via the second communication unit 201 and the first communication unit 106 (S12). The lens authentication information of the interchangeable lens 100 includes model information of the interchangeable lens 100. The lens control unit 105 responds to a request for lens authentication information from the main body control unit 203 via the first communication unit 106 and the second communication unit 201 (S13).

The main body control means 203 requests the lens control means 105 to perform an initialization operation via the second communication means 201 and the first communication means 106 (S14). The lens control unit 105 performs an initialization operation of the aperture unit 103 and the focus lens 104. The lens control unit 105 responds to the main body control unit 203 that the initialization operation has been completed via the first communication unit 106 and the second communication unit 201 (S15).

The main body control unit 203 requests lens data from the lens control unit 105 via the second communication unit 201 and the first communication unit 106 (S16). The lens data is stored in the storage unit 108. The lens control unit 105 reads the lens data from the storage unit 108, and responds to the main body control unit 203 via the first communication unit 106 and the second communication unit 201 (S17). The lens data includes characteristic values unique to the interchangeable lens 100 such as information on backlash, F number, and focal length. In the present embodiment, the information related to backlash is information indicating whether the backlash amount is larger or smaller than a predetermined value.

When the main body control means 203 receives the lens data of the interchangeable lens 100 attached to the camera main body 200, the camera is ready for photographing. The body control unit 203 periodically requests lens state data indicating the state of the interchangeable lens 100 from the lens control unit 105 via the second communication unit 201 and the first communication unit 106 (S18). . The lens state data includes, for example, position information of the zoom lens 102, position information of the focus lens 104, aperture value information of the aperture unit 103, and the like. The lens control unit 105 returns lens state data to the main body control unit 203 via the first communication unit 106 and the second communication unit 201 (S19). The camera body 200 operates in an optical viewfinder mode (see FIG. 1) or a live view mode (see FIG. 2).

2-2. Hereinafter, a driving method of the focus lens 104 during the focusing operation by the phase difference detection method will be described.

When the camera body 200 is operating in the optical viewfinder mode (see FIG. 1), a focusing operation by a known phase difference detection method is performed. The main body control unit 203 recognizes the in-focus state from the output of the focus detection unit 211, and the subject light is converted into the focus plate 206 and the focus from the position information (current position) of the focus lens 104 included in the lens state data received immediately before. The position (target position) of the focus lens 104 for focusing on the detection unit 211 is obtained. The main body control unit 203 requests the lens control unit 105 to move the focus lens 104 to the target position via the second communication unit 201 and the first communication unit 106. The lens control unit 105 controls the driving unit 107 so as to move the focus lens 104 to the target position.

FIG. 7 is a diagram for explaining the operation of the focus lens 104 in the focusing operation by the phase difference detection method. When the information related to backlash included in the received lens data indicates that the backlash amount of the driving means 107 is smaller than a predetermined value (for example, when the driving means 107 has the configuration shown in FIG. 3), The main body control unit 203 transmits a command to the lens control unit 105 so as to move the focus lens 104 from the current position toward the target position regardless of the current position of the focus lens 104. That is, when the current position of the focus lens 104 is closer to the camera body 200 than the target position, the main body control unit 203 determines that the current position of the focus lens 104 is closer to the subject than the target position, as shown in FIG. If it is, the focus lens 104 is moved toward the target position as shown in FIG.

On the other hand, when the information related to backlash included in the received lens data indicates that the backlash amount of the driving means 107 is larger than a predetermined value (for example, when the driving means 107 has the configuration shown in FIG. 4). ) The main body control unit 203 drives the focus lens 104 based on the relationship between the current position of the focus lens 104 and the target position in consideration of the moving direction of the focus lens 104 when the focus lens 104 reaches the current position. Switch methods. Specifically, when the movement direction of the focus lens 104 when the focus lens 104 is moved to the current position is the same as the movement direction for moving the focus lens 104 from the current position to the target position, the focus lens 104 The focus lens 104 is moved to the target position by moving the lens 104 only in the direction from the current position toward the target position. On the other hand, when the movement direction of the focus lens 104 when the focus lens 104 is moved to the current position is different from the movement direction for moving the focus lens 104 from the current position to the target position, the focus lens 104 is moved to the current position. The target lens is moved beyond the target position toward the target position, and then the moving direction is reversed so that the focus lens 104 reaches the target position from the reverse direction. By reversing the moving direction in this way, the influence of backlash can be canceled and the focus lens can be accurately moved to the target position.

For example, as shown in FIG. 7C, when the focus lens 104 reaches the current position from the camera body 200 side, and the current position is closer to the camera body 200 than the target position, the focus lens 104 Control is performed so that 104 is moved from the current position toward the target position. On the other hand, as shown in FIG. 7D, when the focus lens 104 has reached the current position from the camera body 200 side and the current position is closer to the subject side than the target position, the body control means 203. Controls the focus lens 104 to move from the current position toward the target position, pass the target position to the camera body 200 side, and then move the focus lens 104 from the reverse direction to the target position. As described above, when the backlash amount is larger than the predetermined value, the focus lens 104 is always moved from the same direction to the target position, thereby eliminating the influence of the backlash.

As described above, when the backlash amount of the driving unit 107 is smaller than a predetermined value, the focus lens 104 is controlled to move to the target position at a time, thereby realizing the high-speed movement of the focus lens 104. On the other hand, when the backlash amount of the driving means 107 is larger than a predetermined value, the focus lens 104 is always moved from the same direction to the target position regardless of which side the focus lens 104 is on the target position. Control. This counteracts backlash. 7C and 7D, the focus lens 104 is controlled to always move from the camera body 200 side to the target position, but may be controlled to always move from the subject side to the target position. .

2-3. Hereinafter, a driving method of the focus lens 104 during the focusing operation by the hill-climbing method will be described.

When the camera body 200 is operating in the live view mode (see FIG. 2), a focusing operation by a known hill climbing method is performed. The main body control unit 203 can recognize the focus state (focus evaluation value) from the contrast of the image data based on the image signal output from the image sensor 202. The main body control unit 203 requests the lens control unit 105 to move the focus lens 104 by a minute distance via the communication units 201 and 106, and obtains a focus evaluation value each time. By repeating this, the focus lens 104 is moved to a position where the focus evaluation value is maximized (focus position). The in-focus position is an example of a target position.

FIG. 8 is a diagram for explaining the operation of the focus lens 104 in the focusing operation by the hill climbing method. When the information on backlash included in the received lens data indicates that the backlash amount of the driving means 107 is smaller than a predetermined value (when the driving means 107 has the configuration shown in FIG. 3), the main body control Regardless of the focus operation start position of the focus lens 104, the means 203 allows the lens control means 105 to move the focus lens 104 once through the focus position and then move from the reverse direction to the focus position. Send a command. That is, when the focus operation start position of the focus lens 104 is closer to the camera body 200 than the focus position, as shown in FIG. 8A, the focus operation start position of the focus lens 104 is more than the focus position. When it is on the subject side, as shown in FIG. 8B, after passing the focus lens 104 once through the focus position (arrow A in FIGS. 8A and 8B), toward the focus position. The focus lens 104 is moved (arrow B in FIGS. 8A and 8B).

On the other hand, when the information on the backlash included in the received lens data indicates that the backlash amount of the driving unit 107 is larger than a predetermined value (when the driving unit 107 has the configuration shown in FIG. 4), The main body control means 203 performs control as shown in FIGS. In other words, the main body control unit 203 passes the focus lens 104 once through the in-focus position (arrow A in FIGS. 8C and 8D), and then again through the in-focus position in the opposite direction (FIG. 8). 8 (c), (d) arrow B), and then moved toward the in-focus position (arrow C in FIGS. 8 (c), 8 (d)). FIG. 8C shows the operation when the focus operation start position of the focus lens 104 is closer to the camera body 200 than the focus position, and FIG. 8D shows the focus operation start position of the focus lens 104. FIG. 6 is a diagram showing an operation when is located on the subject side with respect to the in-focus position.

As described above, when the backlash amount of the driving unit 107 is smaller than the predetermined value, the focus lens 104 is controlled to move to the in-focus position at a time after passing through the in-focus position. 104 high-speed movement is realized. When the backlash amount of the driving means 107 is larger than a predetermined value, the backlash is canceled by reversing the moving direction of the focus lens 104 twice (directions A → B, B → C).

3. Other Embodiments Other embodiments are listed below.

3-1. In the above-described embodiment, the main body control unit 203 receives the information on the backlash stored in the storage unit 108 via the communication units 201 and 106. However, the method of acquiring information related to backlash by the main body control unit 203 is not limited to this. FIG. 9 is a diagram illustrating an example of simple transmission means for information relating to backlash. The camera body 200 and the interchangeable lens 100 are provided with transmission means 213 and 109 which are electrical connection terminals for giving information on backlash. The transmission means 109 of the interchangeable lens 200 is connected to a high potential or a low potential according to the value of information related to backlash. For example, when the backlash amount of the interchangeable lens 100 is smaller than a predetermined value, the transmission means 109 of the interchangeable lens 100 is connected to a high potential (FIG. 9A), and the backlash amount of the interchangeable lens 100 is a predetermined value. If larger, the transmission means 109 may be connected to a low potential (FIG. 9B).

With such a configuration, when the interchangeable lens 100 is attached to the camera body 200, the main body control unit 203 recognizes the electrical state of the transmission unit 109 via the transmission unit 213 that is an electrical connection terminal. The backlash amount of the interchangeable lens 100 can be determined.

In FIG. 9, the transmission means 109 is directly connected to a high potential or a low potential. However, the transmission means 109 is connected to a lens control means 105 (not shown), and the lens control means 105 is connected to the transmission means. A configuration in which the potential of 109 is controlled may be employed. In addition, a mechanical switch is provided in a mounting portion of the interchangeable lens 100 in the camera body 200, and a protrusion is provided at a position corresponding to the mechanical switch in the interchangeable lens 100 having a backlash amount larger than a predetermined value. The interchangeable lens 100 having a smaller value than the predetermined value may be configured such that no protrusion is provided at a position corresponding to the mechanical switch. The main body control means 203 monitors the state of the mechanical switch, and when the mechanical switch is ON (when the mechanical switch is pressed by the protrusion of the interchangeable lens 100), the backlash amount is It can be recognized that the interchangeable lens 100 larger than a predetermined value is attached. When the mechanical switch is not turned on (when the mechanical switch is not pressed), the main body control unit 203 recognizes that the interchangeable lens 100 whose backlash amount is smaller than a predetermined value is attached. can do.

Also, a plurality of transmission means 109, 213 or mechanical switches may be provided. For example, by providing two transmission means 109 and 213 or two mechanical switches, the main body control means 203 can acquire information on four types of backlash. When information related to backlash is stored in the storage means 108, it goes without saying that the same effect can be obtained by increasing the number of bits of information related to backlash stored in the storage means 108.

3-2. In the configuration shown in FIG. 5, the backlash amount of the drive unit 107 varies depending on the position of the focus lens 104 on the optical axis L. In the configuration shown in FIG. When the main body control unit 203 recognizes that the backlash amount of the driving unit 107 has changed and the interchangeable lens 100 is mounted with a backlash amount larger than a predetermined value, the main communication unit 203, the second communication unit 201, The driving method of the focus lens 104 is determined according to the position information of the focus lens 104 included in the lens state data received from the lens control unit 105 via the first communication unit 106. For example, 1) when the position of the focus lens 104 is closer to the subject than the first predetermined position, and 2) when the position of the focus lens 104 is closer to the camera body 200 than the second predetermined position. 3) The main body control unit 203 changes the control method when the position of the focus lens 104 is between the first predetermined position and the second predetermined position. When it is recognized that the backlash amount of the driving unit 107 is changed and the interchangeable lens 100 is mounted with a backlash amount larger than a predetermined value, the position of the focus lens 104 is more than the first predetermined position. The backlash amount increases when the object is on the subject side and when the focus lens 104 is located on the camera body 200 side with respect to the second predetermined position. Therefore, in this case, the main body control unit 203 performs control so that the focus lens 104 reaches the target position or the in-focus position from the same direction. On the other hand, when the position of the focus lens 104 is between the first predetermined position and the second predetermined position, the backlash amount is small. Therefore, in this case, the main body control unit 203 performs control so that the focus lens 104 can reach the target position or the in-focus position from any direction.

In the embodiment, the control of the focus lens 104 has been described. However, the present invention can be applied to any lens such as the zoom lens 102 that moves forward and backward along the optical axis L. In the embodiment, the main body control unit 203 receives the information on the backlash stored in the storage unit 108 via the communication units 201 and 106 when the imaging system is activated. It is not a thing. The main body control unit 203 may receive information related to backlash when it recognizes the mounting of the interchangeable lens 100 by monitoring the state of the mounting detection unit 212.

3-3. Lens driving during moving image shooting When the imaging system in the embodiment is operating in the live view mode (the state shown in FIG. 2), moving image shooting can be performed. In moving image shooting, it is possible to focus the subject light on the image sensor 202 or maintain the focused state by causing the focus lens 104 to perform a known wobbling operation. FIG. 10 is a diagram for explaining the operation of the focus lens 104 by wobbling. The vertical axis indicates the position of the focus lens 104 on the optical axis L, and the horizontal axis indicates time. In moving image shooting, the main body control means 203 converts the image signal output from the image sensor 202 every frame (every 1/30 seconds) into image data and records it on a recording medium (not shown). The main body control unit 203 recognizes the in-focus state from the contrast of the image data based on the image signal output from the image sensor 202 for each frame. The main body control unit 203 requests the lens control unit 105 via the communication units 201 and 106 to gradually move the focus lens 104 to the in-focus position while moving forward and backward on the optical axis L.

However, when the backlash amount of the driving means 107 is larger than a predetermined value, the focus lens 104 cannot be accurately wobbling. Therefore, when the backlash amount of the driving means 107 is smaller than the predetermined value, the main body control means 203 requests the lens control means 105 to perform the wobbling operation of the focus lens 104, and the backlash of the driving means 107. When the amount is larger than the predetermined value, the focus lens 104 is requested to repeat the focusing operation by the hill-climbing method.

Note that during continuous shooting in which a plurality of still images are obtained by operating the release button once, as in the case of moving image shooting, when the backlash amount of the driving unit 107 is smaller than a predetermined value, the main body control unit 203 When the control unit 105 is requested to perform the wobbling operation of the focus lens 104 and the backlash amount of the drive unit 107 is larger than a predetermined value, the focus lens 104 is hill-climbed to the lens control unit 105. It may be controlled to repeat the focusing operation.

3-4. Combined use with information relating to driving method In the above-described embodiment, only information relating to the driving means is used. However, information relating to the driving method and information relating to the driving means may be used in combination. For example, the information on the driving method is information indicating a specific backlash amount, and the information on the driving means is the specific backlash amount accuracy. The main body control means 203 acquires a specific backlash amount and its accuracy when the camera main body 200 is turned on or when the interchangeable lens 100 is detected. When the specific backlash amount is small and the accuracy is high, the main body control unit 203 may perform control so that the focus lens 104 reaches the target position or the in-focus position from the same direction. When the specific backlash amount is small but the accuracy is low, the main body control unit 203 may perform control so that the focus lens 104 can reach the target position or the in-focus position from any direction.

3-5. Control of the Aperture Unit Since the aperture unit 103 is also usually affected by backlash generated by the driving means, the idea of this embodiment can be applied. For example, it is assumed that the aperture unit 103 can take aperture values of 2, 2.8, 4, 5.6, 8, 11, 16, and 22 as aperture values. Assuming that the target aperture value (target opening) is 8, when the backlash amount, which is information relating to the driving means of the aperture unit 103, is larger than a predetermined value, the aperture unit 103 moves from the current aperture to the target aperture. At this time, control is performed so as to arrive after reversely moving a predetermined number of times across the target opening. When the backlash amount, which is information relating to the driving means of the aperture unit 103, is smaller than a predetermined value, the aperture unit 103 moves in one direction from the current position to the target position (aperture value 5.6 side, aperture value 11). Control to reach (from either side). In the case of still image shooting, the above-described control is performed. In the case of moving image shooting, the movement is performed in one direction regardless of the amount of backlash, which is information related to the driving unit of the aperture unit 103. You may control. In the case of moving image shooting, when the aperture unit 103 moves from the current opening to the target opening, the aperture of the aperture unit 103 is controlled so as to reach after reaching the target opening by reversing a predetermined number of times. This is because once the target opening degree is reached, the target opening degree is reached, so that the brightness and darkness of the photographed image is repeated, making it unsightly.

3-6. Use of Reliability Information The lens control unit 105 acquires information about the state of the driving unit 107, and the main body control unit 203 uses the second communication unit 201, the first communication unit 106 or the second transmission unit 213, and the first transmission unit 213. Information regarding the reliability of the drive unit 107 may be acquired via the transmission unit 109.

The information related to the reliability of the driving unit 107 includes, for example, information related to the reliability of the position information of the zoom lens 102 and the focus lens 104 and information related to the reliability of the aperture value information of the aperture unit 103. Hereinafter, information regarding the reliability of the position information of the focus lens 104 will be described. The information related to the reliability of the position information of the focus lens 104 is information indicating whether or not the position information of the focus lens 104 includes an error due to backlash.

First, lens driving during the focusing operation by the phase difference detection method will be described with reference to FIG. As shown in FIG. 7D, when the focus lens 104 has reached the current position from the camera body 200 side and the current position is closer to the subject than the target position, the body control unit 203 Control is performed so that the focus lens 104 moves to the target position after passing the target position to the camera body 200 side once. At this time, since the movement direction immediately before reaching the current position is different from the movement direction immediately after starting the movement from the current position to the target position, backlash occurs due to the reversal of the movement direction. Further, backlash also occurs when the focus lens 104 is reversed after passing through the target position. If the two backlash amounts are equal, they are canceled out, and the position information of the focus lens 104 included in the lens data received by the main body control means 203 becomes accurate. However, for example, when the backlash amount is different because the configuration of the driving means as shown in FIG. 5 is adopted, the backlash is not canceled and the focus lens 104 included in the lens data received by the main body control means 203 is not canceled. The position information is considered to include an error due to backlash. In this case, the position information of the focus lens 104 included in the received lens data cannot be trusted. Therefore, the lens control unit 105 may notify the main body control unit 203 of information related to the reliability of the position information of the focus lens 104. The main body control unit 203 acquires information on the reliability of the position information of the focus lens 104 from the lens control unit 105, and can determine whether or not the current position information of the focus lens 104 is reliable.

Next, what performs the focusing operation by the hill-climbing method will be described with reference to FIGS. In the case of the example shown in FIGS. 8C and 8D, the main body control means 203 controls as follows. That is, regardless of the focus operation start position of the focus lens 104, once the focus lens 104 passes through the focus position (arrow A in FIGS. 8C and 8D), the moving direction is reversed, After passing the focus lens 104 through the in-focus position again (arrow B in FIGS. 8C and 8D), the moving direction is further reversed to move the focus lens 104 to the in-focus position (FIG. 8 ( c), arrow C) in (d). At this time, the focus lens 104 should operate so as to cancel backlash. For example, since the configuration of the driving unit as shown in FIG. 5 is adopted, the amount of backlash at the time of reversal from direction A to direction B is obtained. When the amount of backlash at the time of reversal from direction B to direction C is different, the backlash is not canceled out. Therefore, the position information of the focus lens 104 included in the lens data received by the main body control unit 203 is not reliable. Therefore, the lens control unit 105 may notify the main body control unit 203 of information related to the reliability of the position information of the focus lens 104. The main body control unit 203 can determine whether or not the current position information of the focus lens 104 is reliable by acquiring information related to the reliability of the position information of the focus lens 104 from the lens control unit 105.

Similarly, in the case of moving image shooting (3-3), the lens control unit 105 acquires information on the reliability of the position information of the focus lens 104, and the main body control unit 203 receives the focus lens 104 from the lens control unit 105. It is possible to determine whether or not the current position information of the focus lens 104 is reliable by acquiring information related to the reliability of the position information. As the case where the current position information of the focus lens 104 is unreliable, there are various situations such as the state immediately after activation and the switching between still image shooting and moving image shooting in addition to the operation of canceling the backlash. Accordingly, the main body control unit 203 can perform various processes using only the position information of the focus lens 104 that is reliable.

3-7. Others In the hill-climbing method, there are the following measures as other measures when the backlash amount of the driving means 107 is larger than a predetermined value. That is, in the hill-climbing method, the focus lens 104 is moved by a relatively long distance, and the coarse tone for recognizing the in-focus state from the contrast of the image data based on the image signal output from the image sensor 202, and the focus lens 104 are relatively When combining the fine adjustment for recognizing the in-focus state from the contrast of the image data based on the image signal output from the image sensor 202 after being moved by a short distance, the focus lens 104 is combined from the same direction in the coarse adjustment and the fine adjustment. It may be controlled to reach the focal position.

Also, in the focusing operation by the hill-climbing method, a surplus range is required outside the range for searching the focus position. This is unavoidable because the focusing operation by the hill-climbing method is a method of searching for a position (focusing position) where the focusing evaluation value is maximum. Therefore, when the backlash amount of the driving unit 107 is larger than a predetermined value, it is preferable to take a larger surplus range than when the backlash amount of the driving unit 107 is smaller than the predetermined value. Further, when the backlash amount of the driving means 107 is larger than a predetermined value, the focusing operation by the hill climbing method may not be performed at both ends of the operating range of the focus lens 104.

Further, a flag indicating information related to the driving means may be set in the interchangeable lens 100 in advance. The flag to be set can be arbitrarily selected by the interchangeable lens manufacturer. At that time, the interchangeable lens manufacturer can select the flag in consideration of various matters such as the positional accuracy of the lens movement, the time required for the lens movement, and the type of the motor.

The idea of the above embodiment can be applied to the focusing operation of the phase difference detection method and the focusing operation of the mountain climbing method. That is, it can be widely applied to general interchangeable lens imaging systems. Therefore, the present invention can be applied to all still image dedicated cameras, moving image dedicated cameras, and still image / moving image combined cameras.

The information on the backlash of the driving means may be information indicating the backlash amount of the driving means in addition to the information indicating the magnitude of the backlash amount of the driving means. Further, the camera body 200 may select an optimal control method for the interchangeable lens 100 based on information related to driving means other than information related to backlash. The information on the driving means includes, for example, the type of motor, the magnitude of the driving resistance, the magnitude of the focal length variable range, the magnitude of current consumption, and the like.

While specific embodiments have been described above, many other variations, modifications, and other uses will be apparent to those skilled in the art. Accordingly, the invention is not limited to the specific disclosure herein, but can be limited only by the scope of the appended claims. The present application includes Japanese patent application, Japanese Patent Application No. 2008-132767 (submitted on May 21, 2008) and Japanese Patent Application No. 2008-139191 (submitted on May 28, 2008), and US Provisional Patent Application, 61/053815. No. (submitted on May 16, 2008), the contents of which are incorporated herein by reference.

According to the present invention, the influence of backlash can be removed and a movable member such as a lens or a diaphragm can be driven with high accuracy, which is useful for an interchangeable lens imaging system such as a single-lens reflex camera system.

DESCRIPTION OF SYMBOLS 100 Interchangeable lens 101 Objective lens 102 Zoom lens 103 Diaphragm unit 104 Focus lens 105 Lens control means 106 Communication means 107 Driving means 108 Storage means 109 Transmission means 200 Camera body 201 Communication means 202 Imaging element 203 Body control means 204 Penta prism 205 Eyepiece 206 Focus plate 207 Main mirror 208 Sub mirror 209 Shutter 210 Image display unit 211 Focus detection unit 212 Wear detection means

Claims (11)

An imaging system including an interchangeable lens and a camera body,
The interchangeable lens is
A movable member;
Driving means for driving the movable member to change the state of the movable member;
Lens control means for controlling the driving means;
Holding means for holding information on backlash of the driving means,
The camera body is
A main body control means for controlling operations of the camera main body and the interchangeable lens;
The main body control means transmits control information for controlling the driving means to the lens control means,
The main body control unit acquires information about the backlash held by the holding unit from the interchangeable lens, and controls the movable member when controlling the state of the movable member to a target state according to the acquired information. Switch the control method of the direction to change the state of the member,
An imaging system characterized by that. The movable member is a lens;
The main body control means controls the driving means by any one of the first control method and the second control method according to the acquired information on the backlash,
In the first control method, when the lens is changed to a target position, the lens is moved from a predetermined direction so as to reach the target position.
In the second control method, the lens is moved from an arbitrary direction to control the lens to reach a target position.
The imaging system according to claim 1. The movable member is a lens;
The main body control means detects the contrast of the image, and performs the driving by the control method of either the first control method or the second control method according to the acquired information on the backlash in the autofocus operation. Control means,
In the first control method, when the lens is changed to the target position, the lens is moved from the same direction as the lens is moved when detecting the contrast of the image so as to reach the target position. Control
In the second control method, the lens is moved from an arbitrary direction to control the lens to reach a target position.
The imaging system according to claim 1. The movable member is a diaphragm;
The main body control means is configured to change the aperture of the throttle from a predetermined direction by changing the aperture of the aperture from a predetermined direction, and to change the aperture of the aperture from an arbitrary direction. The imaging system according to claim 1, wherein the driving unit is controlled by any one of a control method for causing the aperture of the diaphragm to reach a target value. The imaging system according to claim 1, wherein the holding means is a storage means for storing information on backlash of the driving means as data. The holding means is a first electrical connection terminal connected to a predetermined potential corresponding to information related to the backlash, and the camera body is connected to the first electrical connection terminal. The imaging system according to claim 1, further comprising a general connection terminal. 2. The imaging system according to claim 1, wherein the main body control means acquires information on the reliability of the information on the state of the movable member from the lens control means. 2. The imaging system according to claim 1, wherein the main body control means acquires information about the backlash when the imaging system is activated. It further has a detection means for detecting the mounting of the interchangeable lens,
The imaging system according to claim 1, wherein the main body control unit acquires information about the backlash when the detection unit detects the mounting of an interchangeable lens. An interchangeable lens that can be attached to the camera body,
A movable member;
Driving means for driving the movable member to change the state of the movable member;
Lens control means for controlling the driving means;
Holding means for holding information on backlash of the driving means as binary information;
An interchangeable lens characterized by that. A camera body to which an interchangeable lens including a movable member and a driving unit that drives the movable member to change the state of the movable member can be mounted,
A main body control means for controlling operations of the camera main body and the interchangeable lens;
The main body control means transmits control information for controlling the driving means to the interchangeable lens,
The main body control unit acquires information about backlash of the driving unit from the interchangeable lens, and controls the state of the movable member when controlling the state of the movable member to a target state according to the acquired information. Switch the control method of the direction to change,
A camera body characterized by that.

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