JP2019020669A - Control device, lens device, imaging device and control method - Google Patents

Abstract

To provide a control device capable of achieving both of power saving and acceleration of continuous-shooting.SOLUTION: A control device comprises a stepping motor (115) for driving a diaphragm and determination means (102) for determining a second F value on the basis of a first F value and a position of a rotor of the stepping motor. In the case where the first F value does not fall within a predetermined range or a position of the rotor of the stepping motor is not a stable phase, the determination means determines an F value obtained by the minimum driving amount from the first F value out of F values, which fall within the predetermined range and for which a position of the rotor of the stepping motor is a stable phase, as the second F value.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an imaging apparatus having an aperture.

  In imaging apparatuses such as single-lens reflex cameras and mirrorless cameras, phase difference type focus detection (hereinafter sometimes referred to as “phase difference AF”) is used. In addition, an imaging surface phase difference sensor having a structure having a plurality of photoelectric conversion units in one pixel and capable of simultaneously outputting a phase difference signal (focus detection signal) and an image signal is provided as an imaging sensor of the imaging device. Are known.

  However, in order to perform phase difference AF appropriately, a certain level of brightness is required. Therefore, at the time of continuous shooting (continuous shooting), the aperture is driven to the open position every time after the exposure is completed, and then the next focus detection is performed. There is a need. For this reason, it is difficult to increase the continuous shooting frame speed (the number of shooting frames per unit time) during still image shooting.

  Patent Document 1 discloses a camera that drives a diaphragm starting from a predetermined diaphragm value capable of phase difference AF in order to enable phase difference AF during continuous shooting and to shorten the driving time of the diaphragm. Yes. Accordingly, the focus detection can be performed by returning the aperture position to the aperture of a predetermined light amount and performing phase difference AF without driving the aperture to the open position. For this reason, the continuous shooting frame speed can be increased.

JP 2000-162494 A

  However, when a stepping motor or the like is used as the aperture driving means (actuator), energization of the aperture driving means is continued during focus detection or exposure in order to maintain aperture aperture accuracy after the aperture is driven. There is a need.

  On the other hand, when energization is stopped for power saving, the position of the diaphragm changes due to cogging of the stepping motor, and the aperture accuracy of the diaphragm cannot be maintained. As a result, the focus detection based on the phase difference AF is shifted, and it becomes difficult to capture an image desired by the user. For this reason, the camera disclosed in Patent Document 1 cannot achieve both power saving and high-speed continuous shooting.

  SUMMARY An advantage of some aspects of the invention is to provide a control device, a lens device, an imaging device, and a control method that can achieve both power saving and high-speed continuous shooting.

  The control device according to one aspect of the present invention includes a stepping motor that drives the diaphragm, and a determination unit that determines the second F value based on the first F value and the position of the rotor of the stepping motor. When the first F value is not within a predetermined range or when the position of the rotor of the stepping motor is not in a stable phase, the determining means is within the predetermined range and the stepping motor The F value obtained with the minimum driving amount from the first F value among the F values in which the position of the rotor is the stable phase is determined as the second F value.

  A lens device according to another aspect of the present invention includes a focus lens, a focus lens driving unit that drives the focus lens, a diaphragm, and the control device.

  An imaging device as another aspect of the present invention includes the lens device and an imaging element that photoelectrically converts an optical image formed through the lens device.

  The control method according to another aspect of the present invention includes a step of determining a second F value based on a first F value and a position of the rotor of the stepping motor, and the first F value is set to the first F value. Driving the aperture so as to change the F value to 2, and performing focus detection with the second F value, and determining the second F value. When the value is not within a predetermined range or when the position of the rotor of the stepping motor is not in a stable phase, F is within the predetermined range and the position of the rotor of the stepping motor is in the stable phase. Among the values, an F value obtained from the first F value with a minimum driving amount is determined as the second F value.

  Other objects and features of the invention are described in the following embodiments.

  According to the present invention, it is possible to provide a control device, a lens device, an imaging device, and a control method that can achieve both power saving and high-speed continuous shooting.

It is a block diagram of the imaging device in this embodiment. It is a block diagram of the stepping motor in this embodiment. It is explanatory drawing of the stepping motor in this embodiment. It is a flowchart which shows the control method in this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, with reference to FIG. 1, the structure of the imaging device in this embodiment is demonstrated. FIG. 1 is a block diagram of the imaging apparatus 100. The imaging apparatus 100 is a camera system that includes a camera body 150 and a lens device (interchangeable lens) 101 that is detachably attached to the camera body 150. However, this embodiment can also be applied to an imaging apparatus such as a digital camera in which a camera body and a lens apparatus are integrally configured.

  In FIG. 1, the camera body 150 and the lens device 101 can communicate with each other via a communication contact portion (communication terminal 153) in the camera side contact portion 152 and a communication contact portion (communication terminal 104) in the lens side contact portion 103. They are connected and can exchange information. In addition, power is supplied from the power supply circuit unit 155 of the camera body 150 to the power supply circuit unit 106 of the lens device 101 via the power supply contact unit 154 in the camera side contact unit 152 and the power supply contact unit 105 in the lens side contact unit 103. Supplied. The power supply circuit unit 155 of the camera body 150 generates various power sources used in the camera body 150 or power to be supplied to the lens apparatus 101 from the battery 156 attached to the camera body 150 using an LDO, a DCDC circuit, or the like. To do.

  The lens CPU 102 of the lens apparatus 101 is a control unit that controls each unit of the lens apparatus 101. A built-in memory (storage means) 102 a of the lens CPU 102 stores characteristic information and optical information unique to the lens device 101. Note that storage means for storing characteristic information and optical information may be provided outside the lens CPU 102. The lens CPU 102 acquires the characteristic information and the optical information stored in the storage unit, and transmits them to the camera CPU (camera control device) 151 of the camera body 150 via the communication terminals 104 and 153. The characteristic information includes the name of the lens device 101 (ID information for specifying the model, that is, the lens ID), the maximum communication speed, the open F value, whether or not the zoom lens is available, the compatible AF system, and the AF-capable image. Contains advanced information. The optical information includes focus lens 107 sensitivity information, focus correction amount (design value), and focus lens 107 position obtained by a matrix such as the position of the focus lens 107, the position of the zoom lens (magnification lens) 108, and the state of the aperture 109. , Information on focus correction manufacturing error values, and the like. However, the characteristic information and the optical information are not limited to the information described above, and may include other information. The lens apparatus 101 and the camera body 150 also exchange information such as other operation states, setting states, various information request commands (transmission requests), and drive commands via the communication terminals 104 and 153.

  The lens apparatus 101 includes a user interface unit (lens UI) 120 such as a switch (AF / MF switch) for selecting whether to perform autofocus (AF) or manual focus (MF) in a focusing operation. The switch state of the user interface unit 120 is exchanged via the communication terminals 104 and 153.

  The lens apparatus 101 includes an imaging optical system including a zoom lens (magnification lens) 108, a focus lens 107, a diaphragm 109, and a camera shake correction lens 110. The MF drive user interface unit (MF drive UI) 122 is a cylindrical manual focus ring that is provided on the exterior of the lens device 101 and rotates around the optical axis OA of the imaging optical system for manual focus. When the user operates the MF drive user interface unit 122, the detection sensor 123 detects the operation amount and transmits the information to the lens CPU. The lens CPU 102 controls the focus lens driving circuit 112 in accordance with the operation amount of the MF driving user interface unit 122 to drive the focus lens 107 to a predetermined position.

  The zoom drive user interface unit (zoom drive UI) 124 is a cylindrical manual zoom ring that is provided on the exterior of the lens device 101 and rotates around the optical axis OA of the imaging optical system for manual zooming. When the user operates the zoom drive user interface unit 124, the detection sensor 125 detects the operation amount and transmits the information to the lens CPU 102. The lens CPU 102 controls the zoom lens driving circuit 126 according to the operation amount of the zoom driving user interface unit 124, and drives the zoom lens 108 to a predetermined position.

  The imaging element 162 includes a photoelectric conversion element such as a CMOS sensor or a CCD sensor, photoelectrically converts an optical image (subject image) formed via the imaging optical system, and outputs an image signal. The imaging element 162 has a structure having a plurality of photoelectric conversion units for one pixel, and can output an image signal and a phase difference signal (focus detection signal) at the same time. That is, the imaging element 162 is an imaging surface phase difference AF sensor that receives a light beam passing through different pupil regions (pupil partial regions) of the imaging optical system and generates a pair of signals (phase difference signal, focus detection signal). . The camera CPU 151 is focus detection means that performs phase difference focus detection (phase difference AF) based on a pair of signals generated by the image sensor 162.

  Since the camera body 150 is a mirrorless camera that does not include a main mirror that reflects a light beam from a subject that has passed through the imaging optical system, the size of the camera body 150 can be reduced. However, the present embodiment is not limited to a mirrorless camera, and may be a single-lens reflex camera including a main mirror, a pentaprism, a finder, and the like. Further, instead of the imaging surface phase difference AF sensor, a focus detection AF sensor may be separately provided to perform focus detection.

  When confirming that the AF / MF switch of the user interface unit 120 has selected AF, the camera CPU 151 performs an AF operation. The camera CPU 151 processes a pair of signals (phase difference signals) output from the image sensor 162 to detect the focus state of the image pickup optical system, and combines it with the optical information of the lens device 101 described above to focus the subject. The driving amount of the focus lens 107 for obtaining the above is calculated. The camera CPU 151 transmits the calculated driving amount of the focus lens 107 to the lens CPU 102 via the communication terminals 104 and 153. The lens CPU 102 controls the focus lens drive circuit 112 based on the position information of the focus lens 107 from the position sensor 111 that detects the position of the focus lens 107 and the drive amount of the focus lens 107, and moves the focus lens 107 to the in-focus position. To drive.

  When the camera CPU 151 confirms that the AF / MF switch of the user interface unit 120 selects MF, the camera CPU 151 does not perform the AF operation. In this case, the focus lens 107 is driven to a predetermined position by the user operating the MF drive user interface unit 122.

  In response to a half-press operation of a release switch included in the camera user interface unit 161 of the camera main body 150, the camera CPU 151 detects the aperture 109 according to a photometric result by a photometric sensor (not shown) or an aperture value (F value) set by the user. Is calculated. The camera CPU 151 transmits the driving amount of the diaphragm 109 to the lens CPU 102 via the communication terminals 104 and 153. The lens CPU 102 controls the aperture driving circuit 115 based on the driving amount of the aperture 109 received from the camera CPU 151 and the aperture position information from the position sensor 114 that detects the position of the aperture 109, and drives the aperture 109. In the present embodiment, the aperture driving circuit 115 has a stepping motor. In the present embodiment, the lens CPU 102 and the aperture driving circuit 115 constitute a control device.

  The camera CPU 151 transmits a camera shake correction start command to the lens CPU 102 via the communication terminals 104 and 153 in response to a half-press operation of the release switch. When receiving the camera shake correction start command, the lens CPU 102 first controls the IS drive circuit (camera shake correction drive circuit) 116 to hold the camera shake correction lens 110 at the control center position. Subsequently, the lens CPU 102 controls the lock driving circuit 117 to drive the mechanical lock 118 to release the lock state of the camera shake correction lens 110. Thereafter, the lens CPU 102 controls the IS drive circuit 116 according to the detection result of the camera shake detection circuit 119 and drives the camera shake correction lens 110 to correct the camera shake.

  The camera CPU 151 drives the shutter 163 disposed in front of the image sensor 162 in response to the full pressing operation of the release switch, guides the light flux from the image pickup optical system to the image sensor 162, and performs shooting. The camera CPU 151 generates image data based on a signal output from the image sensor 162 and records it as a captured image on a recording medium (not shown) such as an EEPROM. Here, the captured image is a still image when the still image capturing mode is selected by the setting of the camera GUI unit configured to include the display unit 164 and the camera user interface unit 165. On the other hand, when the moving image shooting mode is selected, the captured image is a moving image. Alternatively, a separate recording start button for moving image shooting may be provided, and the moving image recording may be started when the recording start button is pressed.

  Next, the stable phase of the aperture driving circuit (stepping motor) 115 will be described with reference to FIGS. FIG. 2 is a configuration diagram of the stepping motor. FIG. 3 is an explanatory diagram of the stepping motor. A stepping motor rotates a rotating body (rotor) having magnetism such as a magnet by changing an energization pattern to electromagnets arranged in the vicinity with good timing.

  As shown in FIG. 2, a rotating body (magnet) as a rotor is driven using an electromagnet 1 and an electromagnet 2. At this time, when the direction of the current flowing through the electromagnet 1 and the electromagnet 2 is the A direction in FIG. 2, an N pole is generated in the direction of the rotating body. On the other hand, when the current direction is the B direction, an S pole is generated in the direction of the rotating body. Here, when the energization pattern to the electromagnet 1 and the electromagnet 2 is switched in order from FIG. 3A to FIG. Although the stepping motor is driven in this way, if the electromagnet is de-energized in the energization pattern as shown in FIGS. 3B, 3D, 3F, and 3H, FIG. , (C), (e), and (g). This is because the magnet, which is a rotating body, is attracted to the iron core of the electromagnet after being de-energized. Thus, there are an energization pattern in which the rotating body moves when energization to the stepping motor is turned off, and an energization pattern that does not move. FIGS. 3A, 3C, 3E, and 3G are energization patterns called stable phases. That is, the position where the rotating body stops when the electromagnet is turned off is called a stable phase.

  Next, a continuous shooting sequence (control method) related to aperture driving will be described with reference to FIG. 4A and 4B are flowcharts showing a control method in the present embodiment. The flowchart in FIG. 4B is a modification of FIG. Each step of FIGS. 4A and 4B is mainly executed by the lens CPU 102 or the camera CPU 151.

  First, the flowchart shown in FIG. 4A will be described. First, in step S101, the previous exposure during continuous shooting (continuous shooting) ends, the camera CPU 151 closes the shutter 163, and the image sensor 162 completes generation of image data. Subsequently, in step S102, the lens CPU 102 determines that the F value (first F value) of the diaphragm 109 at the end of the previous exposure is the focus by the image sensor (imaging surface phase difference AF sensor) 163 for the next shooting. It is determined whether or not a predetermined range in which detection is possible (AF possible range). F value information within the AF possible range used for this determination (information relating to the first F value) is transmitted via the communication terminals 104 and 153 during the initialization process when the lens apparatus 101 is mounted on the camera body 150. Are transmitted from the camera CPU 151 to the lens CPU 102.

  If it is determined in step S102 that the current F value (first F value) of the diaphragm 109 is not within the AF possible range (a range including the F value capable of focus detection), the process proceeds to step S104. On the other hand, if it is determined that the current F value is within the AF possible range, the process proceeds to step S103. In step S103, the lens CPU 102 determines whether or not the position of the rotating body (rotor) of the stepping motor corresponding to the current F value (first aperture value) is a stable phase of the stepping motor. That is, the lens CPU 102 determines whether or not the stepping motor corresponding to the current aperture stop position is stopped in a stable phase. If the position of the stepping motor is not stable in step S103, the process proceeds to step S104. On the other hand, when the position of the stepping motor is in the stable phase, the process proceeds to step S106.

  In step S104, the lens CPU (determining means) 102 is within a predetermined range in which phase difference AF is possible (within an AF possible range), and the first F of the F values in which the position of the stepping motor is in a stable phase. The F value obtained from the value with the minimum driving amount is determined as the second F value. That is, the lens CPU 102 determines the stop position so that the current F value becomes a bright F value capable of focus detection with the minimum driving amount.

  Subsequently, in step S105, the lens CPU 102 controls the aperture driving circuit (stepping motor) 115 to drive the aperture 109 to the position determined in step S104 (so as to have the second F value). That is, after the lens CPU 102 determines the second F value, the diaphragm driving circuit 115 drives the diaphragm 109 so as to change the first F value to the second F value. Subsequently, in step S106, the lens CPU 102 transmits the current F value (first F value or second F value) to the camera CPU 151. Subsequently, in step S107, the camera CPU (focus detection means) 151 performs focus detection based on the F value information and other optical information transmitted from the lens CPU.

  Next, a modification of FIG. 4A will be described with reference to the flowchart of FIG. First, in step S201, the previous exposure during continuous shooting (continuous shooting) ends, the camera CPU 151 closes the shutter 163, and the image sensor 162 completes generation of image data. Subsequently, in step S <b> 202, the camera CPU 151 transmits F value information (information relating to the first F value) within the AF possible range to the lens CPU 102 via the communication terminals 104 and 153. The subsequent steps S203 to S208 are the same as steps S102 to S107 in FIG.

  Thus, the lens CPU (determining means) 102 determines the second F value based on the first F value and the position of the rotating body of the stepping motor. Further, in a predetermined case, the lens CPU 102 calculates an F value obtained from the first F value with the minimum driving amount among the F values within a predetermined range and the position of the rotating body of the stepping motor is a stable phase. Is determined as the F value. The predetermined case is a case where the first F value is not within a predetermined range or the position of the rotating body of the stepping motor is not in a stable phase. On the other hand, the stepping motor does not drive the diaphragm 109 when the first F value is within a predetermined range and the position of the rotating body of the stepping motor is in a stable phase. At this time, the camera CPU (focus detection means) 151 performs focus detection with the first F value. Preferably, the lens CPU 102 changes the predetermined range according to the first F value. More preferably, the lens CPU 102 further changes the predetermined range based on the luminance of the light beam passing through the stop 109. Preferably, after the stepping motor drives the diaphragm 109 to a position corresponding to the second F value, the driving power to the stepping motor is reduced (turned off). Preferably, when the stepping motor does not drive the aperture 109, the driving power to the stepping motor is reduced (turned off) until the camera CPU 151 completes focus detection.

  According to the present embodiment, since the position of the diaphragm is in a stable phase at the time of focus detection, the position of the diaphragm does not change even when the energization to the driving unit is reduced or turned off. For this reason, it is possible to perform focus detection with high accuracy and power saving. In addition, since it is not necessary to drive the aperture to the open position, it is possible to increase the continuous shooting frame speed (the number of shot frames per unit time). As a result, according to the present embodiment, it is possible to provide a control device, a lens device, an imaging device, and a control method that can achieve both power saving and high-speed continuous shooting.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

102 Lens CPU (determination means)
115 Aperture drive circuit (stepping motor)

Claims (13)

A stepping motor that drives the aperture;
Determining means for determining a second F value based on the first F value and the position of the rotor of the stepping motor;
When the first F value is not within a predetermined range or when the position of the rotor of the stepping motor is not in a stable phase, the determining means is within the predetermined range and the rotation of the stepping motor A control device, wherein an F value obtained with a minimum drive amount from the first F value is determined as the second F value among F values whose child positions are the stable phase.   The stepping motor drives the diaphragm so as to change the first F value to the second F value after the determining means determines the second F value. The control apparatus according to 1. A focus detection means for performing focus detection based on the light flux passing through the diaphragm;
3. The focus detection unit according to claim 2, wherein the focus detection unit performs the focus detection after the stepping motor drives the diaphragm to change the first F value to the second F value. 4. Control device. The stepping motor does not drive the diaphragm when the first F value is within the predetermined range and the position of the rotor of the stepping motor is in the stable phase,
The control apparatus according to claim 3, wherein the focus detection unit performs the focus detection using the first F value.   5. The control device according to claim 1, wherein the determination unit changes the predetermined range in accordance with the first F value.   The control device according to claim 5, wherein the determination unit further changes the predetermined range based on a luminance of a light beam passing through the diaphragm.   7. The drive power to the stepping motor is reduced after the stepping motor drives the aperture to a position corresponding to the second F value. 8. Control device.   5. The control device according to claim 3, wherein, when the stepping motor does not drive the diaphragm, drive power to the stepping motor is reduced until the focus detection unit completes the focus detection.   The control device according to claim 1, wherein the predetermined range is a range including an F value capable of focus detection. A focus lens,
Focus lens driving means for driving the focus lens;
Aperture,
A stepping motor for driving the diaphragm;
Determining means for determining a second F value based on the first F value and the position of the rotor of the stepping motor;
When the first F value is not within a predetermined range or when the position of the rotor of the stepping motor is not in a stable phase, the determining means is within the predetermined range and the rotation of the stepping motor A lens apparatus, wherein an F value obtained by a minimum driving amount from the first F value among F values whose child positions are in the stable phase is determined as the second F value. A lens device according to claim 10;
An imaging device comprising: an imaging device that photoelectrically converts an optical image formed through the lens device. It further has a focus detection means for performing focus detection of a phase difference method,
The imaging element is an imaging surface phase difference AF sensor that receives a light beam passing through different pupil regions of the lens device and generates a pair of signals,
The imaging apparatus according to claim 11, wherein the focus detection unit performs the focus detection based on the pair of signals. Determining a second F value based on the first F value and the position of the rotor of the stepping motor;
Driving the diaphragm to change the first F value to the second F value;
Performing focus detection with the second F value,
In the step of determining the second F value, when the first F value is not within a predetermined range or when the position of the rotor of the stepping motor is not in a stable phase, the second F value is within the predetermined range. In addition, the F value obtained by the minimum drive amount from the first F value among the F values in which the position of the rotor of the stepping motor is the stable phase is determined as the second F value. Control method to do.