JP6581472B2 - Lens apparatus and imaging apparatus having the same - Google Patents

Description

  The present invention relates to a lens apparatus, and more particularly to a lens apparatus having a zoom lens and a diaphragm and an imaging apparatus having the same.

  In recent years, zoom lens apparatuses that employ an optical arrangement in which the F-number changes according to the position of the zoom lens even when the aperture diameter of the stop is the same have come out for reasons such as downsizing. In such a zoom lens apparatus, it is necessary to change the aperture diameter of the diaphragm in conjunction with the zoom lens position. However, if the mechanism is to be realized mechanically, there is a problem that it is expensive and large.

  In order to solve this problem, Patent Document 1 proposes an optical device that electrically controls the aperture diameter of the diaphragm according to the zoom position.

Japanese Patent Laying-Open No. 2015-052737

  When the aperture diameter of the diaphragm is controlled electrically according to the zoom position, high followability is required. In order to achieve high followability, control at high speed and high acceleration is required, but a stepping motor is often used for the drive actuator of the diaphragm, and the possibility of step-out increases. In order to prevent step-out, it is necessary to set a high current to the stepping motor and apply a large force, but the power consumption increases.

  An object of the present invention is to provide a lens device capable of suppressing power consumption while controlling a diaphragm aperture diameter with high followability according to a zoom position, and an imaging device having the lens device.

  In order to achieve the above object, a lens apparatus of the present invention includes a variable aperture unit, aperture operation means for operating the aperture unit, a stepping motor for driving the aperture unit, a zoom unit for changing a focal length, Based on the zoom position detecting means for detecting the position of the zoom unit, the state of the zoom unit and the state of the aperture unit, a driving current of the stepping motor is derived, and the aperture operation is performed according to the position of the zoom unit Control means for controlling the stepping motor with the drive current to drive the aperture section so that the F value set by the means is obtained.

  According to the present invention, it is possible to provide a lens device capable of suppressing power consumption while controlling a diaphragm aperture diameter with high followability according to a zoom position, and an imaging device having the lens device.

Configuration block diagram of lens device Diagram showing the relationship between zoom position, aperture position, and F number Flow chart of overall processing in CPU 30 Flow chart of aperture origin detection processing The figure which showed A phase aperture drive current Ia and B phase aperture drive current Ib for every drive pattern Zoom drive processing flowchart Flowchart of aperture current amplitude setting process The figure which showed the relationship between the position of the zoom speed volume 18, and the zoom speed coefficient Kz. The figure which showed the relationship between a zoom position, F number, and aperture interlocking speed coefficient Ki Aperture drive processing flowchart Diagram showing time variation of aperture drive position and speed

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

  FIG. 1 shows a configuration of a lens apparatus to which the present invention can be applied.

  The zoom lens group 10 (zoom unit) is an optical element for changing the focal length of the lens device by moving in the optical axis direction. The zoom ring 11 is a rotation operation member (zoom position operation means) for controlling the position of the zoom lens group 10 and can be mechanically moved in the optical axis direction by rotating.

  The zoom position detector 12 is a position detector for detecting the rotational position of the zoom ring 11. However, since the rotation position of the zoom ring 11 and the position of the zoom lens group 10 are mechanically connected so as to be in a one-to-one relationship, the zoom position detector 12 also detects the position of the zoom lens group 10. become. The detected position signal is converted into a digital signal as a zoom position and input to the CPU 30 (control means).

  The zoom clutch 13 is a mechanism for connecting or disconnecting the rotation of the zoom motor 14 and the rotation of the zoom ring 11, and can be switched between connection and disconnection by a zoom clutch switch 15. The connected state is a servo state (servo-driven state), and the disconnected state is a manual state, and a signal indicating which state is input to the CPU 30.

  The zoom motor 14 is a motor for electrically driving the zoom ring 11 and is controlled by the CPU 30 via the zoom motor drive circuit 16. The zoom motor 14 is a DC brush motor, and a predetermined speed control (zoom speed control) can be performed by instructing a voltage to be applied from the CPU 30. The zoom seesaw 17 is an operation member (zoom speed operation means) for operating the zoom lens group 10, and when it is not operated, it returns to the midpoint position. The zoom speed volume 18 is an operation member for changing the zoom operation speed. The zoom speed when the zoom clutch 13 is in the servo state is determined by the CPU processing described later according to the operation position of the zoom seesaw 17 (hereinafter referred to as the seesaw position) and the position of the zoom speed volume 18 (hereinafter referred to as the volume position). The drive speed of the zoom lens group 10 is determined.

  The aperture 20 is a variable aperture that can adjust the luminous flux of light passing through the lens device by mechanically changing the aperture diameter by rotating. The aperture stepping motor 21 is a motor for rotationally driving the aperture 20 and is controlled by the CPU 30 via the aperture motor drive circuit 25. In this embodiment, the aperture stepping motor 21 is a two-phase stepping motor that is driven by two driving signals of A phase and B phase, and the driving mode is microstep driving. The aperture origin sensor 22 is a sensor that detects whether or not the aperture 20 is at a predetermined position near the open position. When the aperture origin sensor 22 is rotated to a predetermined position near the open position, the sensor is turned on. The absolute position of the rotation position of the diaphragm 20 (hereinafter referred to as the diaphragm position) is determined according to the processing flow of FIG. 4 described later, triggered by the fact that the diaphragm origin sensor 22 is turned on, and thereafter, the rotational drive from the absolute position is performed. The position is determined from the amount (corresponding to the displacement amount). The aperture operation ring 23 (aperture operation means) is an operation ring for manually operating the F value, which is not mechanically (mechanically) connected to the aperture 20, and is referred to as an operation position (hereinafter referred to as an aperture operation position). ) Is detected by the aperture operation position detector 24, converted into a digital signal, and input to the CPU 30.

  The CPU 30 controls the zoom motor 14 and the aperture stepping motor 21 by software processing described later.

  A camera device 50 having an imaging element 51 that receives subject light from the lens device is connected to the lens device of the present invention to constitute the imaging device.

  In addition, the lens apparatus of the present embodiment has an optical arrangement in which the F number of the lens apparatus changes due to optical characteristics when the zoom position is changed while the aperture position is fixed. In order to maintain the F number, it is necessary to control the aperture position (opening) to an appropriate position according to the zoom position as shown in FIG. The aperture operation ring 23 is an operation member for designating the F number of the lens device, and rotationally drives the aperture 20 with the F number corresponding to the aperture operation position as a target by software processing described later.

  Next, software processing performed by the CPU 30 will be described. FIG. 3 is a flowchart of overall processing performed by the CPU 30 in the first embodiment.

  The entire process is divided into four. First, the aperture origin is detected in S101, the zoom drive process is performed in S102, the aperture current amplitude setting process is performed in S103, the aperture drive process is performed in S104, and then the process returns to S102 and S102 to S104 are performed. repeat.

  The diaphragm origin detection process performed in S101 will be described. FIG. 4 is a flowchart of the aperture origin detection process in the first embodiment.

  In S201, the aperture current amplitude I0 is set to the maximum value Imax. As shown in FIG. 5, the aperture current amplitude I0 indicates the amplitude of the sinusoidal drive pattern of the A-phase aperture drive current Ia and the B-phase aperture drive current Ib in the microstep drive. The aperture driving currents Ia and Ib are controlled by a general PWM method, and are controlled by the ratio (duty ratio) of the time for applying the voltage in the positive direction and the time for applying the voltage in the negative direction. That is, if the time for applying the voltage in the positive direction is the same as the time for applying the voltage in the negative direction, the aperture driving currents Ia and Ib are 0. If the time for applying the voltage in the positive direction is long, the aperture driving current Ia , Ib becomes a positive value. In S202, as shown in the initial drive pattern of FIG. 5, the A-phase aperture drive current Ia is set to + Imax, and the B-phase aperture drive current Ib is set to 0.

  In S203, it is determined whether the aperture origin sensor 22 is ON. If not, the process proceeds to S204, and the aperture 20 is changed by changing the drive pattern from the initial drive pattern in FIG. 5 to the left side in the drawing. Driven in the OPEN direction. The diaphragm 20 is rotationally driven in the OPEN direction until the diaphragm origin sensor is turned on, and the amount of change in the drive pattern per unit time is maximized, so that the diaphragm 20 is rotationally driven to the OPEN side at the highest speed.

  When the diaphragm origin sensor 22 is turned on in S203, the process proceeds to S205, where the amount of change in the drive pattern per unit time is reduced, and the diaphragm 20 is rotationally driven to the OPEN side at a low speed. The process of S205 is performed until the drive pattern becomes the initial drive pattern. When the drive pattern becomes the initial drive pattern, the aperture position is initialized to zero.

  Next, the zoom drive process performed in S102 will be described. FIG. 6 is a flowchart of the zoom driving process in the first embodiment.

  In S301, it is determined whether or not the zoom clutch 13 is in the manual state. If it is in the manual state, the process proceeds to S302, and the zoom motor drive voltage is set to zero. On the other hand, if the zoom clutch 13 is in the servo state (servo-driven state) in S301, the process proceeds to S303 and S304, and the seesaw position is obtained from the zoom seesaw 17 and the volume value is obtained from the zoom speed volume 18. In S305, the zoom motor drive voltage is derived from the obtained seesaw position and volume position. In S306, the zoom motor drive voltage derived in S302 or S305 is output.

  Next, the aperture current amplitude setting process performed in S103 will be described. FIG. 7 is a flowchart of the aperture current amplitude setting process.

  In S401, based on the zoom position acquired from the zoom position detector 12, it is determined whether or not the zoom is being operated (the state of the zoom unit). If the zoom is operated, the process proceeds to S402 and S403, and it is determined whether the zoom clutch 13 is in the servo state (the state of the zoom unit) and the zoom seesaw 17 is operated. When the zoom clutch 13 is in the servo state and the zoom seesaw 17 is being operated, the process proceeds to S404, and the zoom speed coefficient Kz is calculated based on the volume position acquired from the zoom speed volume 18. The zoom speed coefficient Kz is a coefficient for calculating the aperture current amplitude, and is a coefficient indicating the increase rate of the aperture current amplitude due to the zoom speed. Specifically, as shown in FIG. 8, it is changed by about 1.0 to 1.5 depending on the volume position. On the other hand, if the zoom clutch 13 is in the manual state or the zoom seesaw 17 is not operated in S402 and S403, the process proceeds to S405 and the zoom speed coefficient Kz is set to 2.0. Proceeding to S405 indicates that the zoom is manually operated. In a state where the zoom is driven by the servo, the maximum zoom drive speed is limited by the maximum push amount of the zoom seesaw 17. On the other hand, when the zoom is operated manually, the rotation angle of the zoom ring or the like directly becomes the amount of displacement of the zoom position, so there is a possibility that the zoom moves at a higher operation speed than in the servo state. Accordingly, in S405, it is determined that the manual operation is faster than the motor driving, and the zoom speed coefficient Kz is set to a high value. In this embodiment, since the zoom clutch 13 can be manually operated even in the servo state, it is determined whether or not the seesaw operation has been performed in S403. However, assuming that the zoom clutch 13 is not manually operable in the servo state, the determination in S403 may be omitted, and it may be determined whether the process proceeds to S404 or S405 only in the state of the zoom clutch 13.

  Subsequently, the zoom position and aperture ring position are acquired in S406, and the aperture interlocking speed coefficient Ki is derived from the zoom position and aperture ring position acquired in S407. The aperture interlocking speed coefficient Ki is a coefficient for deriving the aperture current amplitude, and is a coefficient indicating the increase rate of the aperture current amplitude due to the aperture interlocking speed. As shown in FIG. 9, the larger the aperture change amount per zoom position change amount for maintaining the F number, the larger the aperture interlocking speed coefficient Ki is set as the zoom position is larger (the zoom position is telephoto and the F value is larger). In this embodiment, it is set at about 1.0 to 2.0.

  In S408, a value obtained by multiplying the minimum current amplitude I1 during aperture driving by the zoom speed coefficient Kz and the aperture interlocking speed coefficient Ki derived so far is set as the aperture current amplitude I0. Since both Kz and Ki are coefficients of 1 or more, the aperture current amplitude I0 derived here is always larger than the minimum current amplitude I1 during aperture drive.

  On the other hand, if the zoom operation is not performed in S401, the process proceeds to S409, where it is determined whether the aperture operation ring 23 is operated based on the aperture operation position acquired from the aperture operation position detector 24. When the aperture operation ring is operated, the process proceeds to S410, and the aperture current amplitude I0 is set to the minimum current amplitude I1 during aperture drive. On the other hand, if the diaphragm operating ring is not operated, the process proceeds to S411, and the diaphragm current amplitude I0 is set to a stop-time current amplitude Imin smaller than I1.

  That is, in the aperture current amplitude setting process of FIG. 7, the aperture current amplitude I0 is set according to the state of the zoom unit, and the maximum drive speed of the aperture is defined by this aperture current amplitude, as will be described later. The state of the zoom unit is a state such as whether the zoom is operated, whether the zoom clutch is in the servo state or the manual state, whether the zoom seesaw is operated, or the like.

  The diaphragm current amplitude I0 set in S410 or S411 when branching from S401 to S409 without a zoom operation is greater than the diaphragm current amplitude I0 set in S408 when branching from S401 to S402 with a zoom operation. It will never get smaller. This is because in S408, the diaphragm drive minimum current amplitude I1 is multiplied by one or more coefficients Kz and Ki to set the diaphragm current amplitude I0. When there is no aperture operation and there is a zoom operation, the operator does not intentionally operate the aperture, so an image that gives a sense of incongruity when the F value that is not intended to change during the zoom operation changes. End up. Therefore, when there is no aperture operation and there is a zoom operation, it is necessary to quickly move the aperture so as to keep the F value constant according to the zoom operation, and it is necessary to set a large aperture current amplitude I0. is there. In addition, in the case of manual aperture operation, the F value is intentionally changed. Therefore, even if there is a slight follow-up delay in the actual movement of the aperture mechanism with respect to the motion of the operation unit such as the aperture operation ring, the imaging is performed. Since the uncomfortable feeling given to the image is small, the aperture current amplitude I0 can be set.

  Finally, the aperture driving process performed in S104 will be described. FIG. 10 is a flowchart of the aperture driving process.

  In S501, based on the diaphragm current amplitude I0 set in S103, the CPU 30 (maximum speed deriving means) derives the diaphragm acceleration A and the maximum diaphragm speed Smax. In this embodiment, the aperture acceleration A and the maximum aperture speed Smax increase in proportion to the aperture current amplitude I0. In S502 and S503, the aperture operation position is acquired from the aperture operation position detector 24, and the zoom position is acquired from the zoom position detector 12. In step S504, the aperture target position that is the target position of the aperture 20 is derived from the acquired aperture operation position and zoom position. The derivation method uses a table calculation that outputs the aperture target position from two inputs of the aperture operation position and the zoom position.

  Subsequently, in S505, the aperture speed is derived from the current aperture position and the aperture target position derived in S504. At this time, the aperture acceleration A derived in S501 and the maximum aperture speed Smax are used to accelerate at the aperture acceleration A, limit the velocity at the maximum aperture speed Smax, and decelerate at the aperture acceleration A to reduce the aperture. The aperture speed is derived so as to reach the target position. The method for deriving the aperture speed is a general derivation method, and is omitted here.

  In S506, drive patterns of the diaphragm drive currents Ia and Ib are derived and output using the diaphragm speed derived in S505 and the diaphragm current amplitude I0 set in S103. In the calculation of the drive pattern, first, the current amplitude of the drive pattern is determined based on the aperture current amplitude I0, and the amount of change in the drive pattern per unit time is determined according to the aperture speed. When the aperture speed derived in S505 is the OPEN side, the drive pattern shown in FIG. 5 is changed to the left side, and when the aperture speed is the CLOSE side, the drive pattern shown in FIG. 5 is changed to the right side.

  The effect of the present embodiment will be described. In this embodiment, as shown in the flowchart of FIG. 7, the current amplitude of the drive pattern of the A-phase and B-phase drive currents flowing to the aperture stepping motor 21 is set. Specifically, in S402 to S405, a zoom speed coefficient Kz corresponding to the maximum expected zoom speed is derived, and in S406 and S407, an aperture interlocking speed coefficient Ki corresponding to the required interlocking speed of the aperture due to zoom movement is derived, The current amplitude is derived from the two coefficients. That is, the current amplitude corresponding to the expected maximum speed of the diaphragm due to the zoom movement is derived. Therefore, since the current amplitude is reduced in the state where the expected maximum speed of the diaphragm is small, the power consumption can be kept low, and in the state where the predicted maximum speed of the diaphragm is large, the current amplitude is increased and the diaphragm is quickly moved. It is possible not to step out even when driven.

  In this embodiment, the current amplitude is derived from the two of the zoom speed coefficient Kz and the aperture interlocking speed coefficient Ki. However, the process is simplified so that only one of the zoom speed coefficient Kz and the aperture interlocking speed coefficient Ki is achieved. A sufficient effect can be obtained even if the current amplitude is derived by. For example, unlike the present embodiment, in the case of a lens apparatus that is not electrically driven for zooming, the processing of S402 to S405 is not performed, and the same processing may be performed by fixing Kz to 2.0. The effect is obtained.

10 Zoom lens group (zoom part)
12 Zoom position detector (position detection means)
20 Aperture (variable aperture)
21 Aperture stepping motor 30 CPU (maximum speed deriving means, control means)

Claims (7)

A variable aperture,
Aperture operation means for operating the aperture section;
A stepping motor for driving the diaphragm,
A zoom section for changing the focal length;
Zoom position detecting means for detecting the position of the zoom unit;
The drive current of the stepping motor is derived based on the state of the zoom unit and the state of the aperture unit, and the drive is performed so that the F value set by the aperture operation unit according to the position of the zoom unit is obtained. Control means for controlling the stepping motor with current and driving the aperture;
A lens device comprising:   The control means derives the driving current based on at least one of a position of the zoom unit, whether the zoom unit is manually operated or servo-driven, and the set F value. The lens device according to claim 1.   The lens apparatus according to claim 2, wherein the driving current when the zoom unit is manually operated is larger than the driving current when the zoom unit is servo-driven.   The control means derives the drive current of the diaphragm unit based on an interlocking speed coefficient that is a change amount of the position of the diaphragm unit with respect to a change amount of the position of the zoom unit so that the set F value is obtained. The lens device according to claim 1, wherein the lens device is a lens device. Zoom speed operating means for operating the servo drive speed of the zoom unit;
The lens apparatus according to claim 3, wherein the control unit derives the driving current based on a speed of the zoom unit set by the zoom speed operation unit.   When the zoom unit is not moving, the control unit controls the aperture unit according to the position of the zoom unit so as to maintain the F value with a smaller current than when the zoom unit is moving. The lens apparatus according to claim 1, wherein the stepping motor is controlled to be driven.   An imaging apparatus comprising: the lens apparatus according to claim 1; and an imaging element that receives subject light from the lens apparatus.

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