JP2016048317A - Optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical apparatus of rear-focus system capable of allowing a user to reliably perform flange back adjustment manually.SOLUTION: The optical apparatus of rear-focus system has means for switching the mode between a first mode and a second mode. When the optical apparatus is in the second mode and the zoom position is at a telephoto side exceeding a predetermined position, the optical apparatus calculates the focus target position in the same manner as in the first mode. When the optical apparatus is in the second mode and the zoom position is at a wide angle side exceeding the predetermined position, the optical apparatus calculates the focus target position so that the focus target position can be set in a range wider than in the first mode.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical device, and more particularly to an optical device that electrically drives an optical element.

  In recent years, in zoom lens apparatuses for still image shooting or moving image shooting, portability is more important, and a small and lightweight device is required. Therefore, many zoom lens apparatuses employing a rear focus method in which a focus lens for focus adjustment is closer to the image sensor than a zoom lens for changing magnification have been developed.

  In the rear focus type zoom lens apparatus, data for correcting the flange back position is stored, and the focus lens is controlled using this data so that no optical element for adjusting the flange back position is provided. There is. In this method, when the flange back position changes due to replacement of a camera attached to the zoom lens device or the like, it is necessary to perform predetermined flange back adjustment work to acquire and update correction data.

  In Patent Document 1, an automatic focusing function is used to focus a subject on each of the zoom position on the telephoto side and the wide-angle side, and correction data is acquired from the position of each focus lens.

JP 2000-121911 A

  However, in the prior art disclosed in the above-mentioned patent document, the subject is focused using the automatic focusing function, and the zoom lens device itself has an automatic focusing function or the connected camera has an automatic focusing function. There must be.

  It is also possible to manually focus the subject by operating the focus lens. In this case, there are two methods, a method of making the operation amount of the focus operation member correspond to the object distance, and a method of making the operation amount of the focus operation member correspond to the focus lens.

  In the former case, the focus lens is controlled so as to maintain the object distance even when the zoom position is changed, which is the same as a normal operation, so that the operator can operate without feeling uncomfortable. However, when the flange back position is greatly deviated and the operation amount of the focus operation member is mechanically limited, the focus lens position for focusing on the subject may not be operated. In general, when the zoom position is on the wide-angle side, the amount of movement of the focus lens due to the change in the object distance is small, and thus there are cases where the amount of movement of the focus lens cannot be manipulated by the deviation of the flange back position.

  In the latter case, unlike the normal operation, it is necessary to set the focus lens operation range very wide so that the entire zoom position can be focused. growing. Therefore, in order to focus on the subject with high accuracy, a more delicate operation of the focus operation member is required, which makes it difficult for the operator to operate.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rear focus type optical device that is easy for an operator to operate and can reliably perform flange back adjustment during flange back adjustment by manual operation.

  In order to achieve the above object, the present invention provides a zoom means for changing a focal length, a zoom position detection means for detecting a zoom position, a focus means for changing an object distance, and a focus position detection means for detecting a focus position. A focus driving means for electrically driving the focusing means, a focus operating means for rotating the focusing means whose mechanical rotation range is limited mechanically, and correcting the position of the focusing means according to the flange back position FB adjustment value storage means for storing a flange back correction value for performing focus focus position calculation for calculating a focus target position of the focus means from the zoom position, the operation position of the focus operation means, and the flange back correction value And a first focus mode optical device having a first focusing mode. Mode switching means for switching between the first mode and the second mode, and the focus target position calculation means is the same as in the first mode when in the second mode and when the zoom position is on the telephoto side from the predetermined position. The focus target position is calculated, and the focus target position can be set in a wider range than the first mode in the second mode and when the zoom position is on the wide-angle side from the predetermined position. A focus target position is calculated.

  According to the present invention, it is possible to provide a rear focus type optical device that is easy to be operated by an operator and can be reliably adjusted during flange back adjustment by manual operation.

FIG. 1 is a block diagram illustrating a configuration of a zoom lens device 1 according to a first embodiment and a second embodiment. The figure which showed the focus position which focuses with the zoom position in the rear focus method The flowchart which shows the software processing performed by CPU25 in Example 1. Diagram showing the focus lens target position in normal mode The figure which showed the focus target position when the focus is operated in the FB adjustment mode The figure which showed the focus target position when zooming in FB adjustment mode Figure showing the flange back adjustment procedure The figure which showed the problem at the time of FB adjustment in the prior art The figure which showed the effect of this invention Flowchart illustrating software processing performed by the CPU 25 in the second embodiment. Flow chart showing focus target position calculation 3 The figure which showed the focus target position by focus target position calculation 3

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

(Example 1)
FIG. 1 shows a configuration of a rear focus zoom lens apparatus 1 according to a first embodiment to which the present invention can be applied. The zoom lens group 11 is an optical element for changing the focal length of the zoom lens device 1 by moving in the optical axis direction. The zoom operation ring 14 is an operation ring for mechanically operating the zoom lens group. By performing a rotation operation, the zoom lens group 11 can be moved straight in the optical axis direction by the cam member 15. The optical axis direction indicates the left-right direction in FIG.

  The zoom position detector 22 is a position detector for detecting the position of the zoom lens group 11 (hereinafter referred to as zoom position). The detected position signal is converted into a digital signal and input to the CPU 25.

  The focus lens group 12 is an optical element for displacing the image forming position of the zoom lens device 1 by moving in the optical axis direction, and can be driven by the focus motor 16 from the CPU 25 via the focus drive circuit 24. Is possible. The position of the focus lens group 12 (hereinafter referred to as a focus position) is converted into a digital signal by the focus position detector 23 and input to the CPU 25.

  The focus operation ring 13 is an operation ring for operating the focus lens group 12, and its operation position (hereinafter referred to as a focus operation position) is converted into a digital signal by the focus operation ring position detector 21 and input to the CPU 25. The In this embodiment, it is assumed that the rotation range of the focus operation ring 13 is mechanically limited.

  The FB adjustment switch 20 is a switch for switching between “normal mode” and “FB adjustment mode”.

  The CPU 25 is a control device for electrically controlling the focus lens group 12 and inputs a zoom position, a focus position, and a focus operation position, and generates a control signal by software processing described later.

  The EEPROM 26 is a device for storing flange back (hereinafter referred to as FB) correction data. The FB correction data is data for correcting the position of the focus lens group 12 for focusing in accordance with the FB position that changes depending on the position of the image sensor of the camera attached to the zoom lens device 1. A method of using the FB correction data will be described later.

  Since the zoom lens device 1 of the present embodiment is a rear focus type zoom lens device, as shown in FIG. 2, if the zoom position changes while the focus position is fixed, the object distance changes. Therefore, when the focal length is changed without changing the object distance, the focus lens group 12 must be controlled to an appropriate position according to the zoom position.

  Next, software processing performed by the CPU 25 will be described. FIG. 3 is a flowchart of software processing performed by the CPU 25 in this embodiment. In S101, the FB correction data X is read from the EEPROM 26 and stored in a RAM (not shown) in the CPU 25. In S102, the state of the FB adjustment switch 20 is confirmed. If it is “normal mode”, the process proceeds to S103. In S103, the object distance is calculated from the focus operation position R acquired from the focus operation ring position detector 21, and is set as the target object distance Lt. The target object distance Lt is calculated only from the focus operation position R, and is calculated using a table stored in advance.

  Subsequently, in S104, a target position (hereinafter referred to as a focus target position) Ft of the focus lens group 12 is calculated. The focus target position Ft is calculated from the zoom position Z, the target object distance Lt, and the FB correction data X using the following formula 1.

  The calculation of the function f1 (Z, Lt) used here uses a table using two parameters of the zoom position Z and the target object distance Lt, as in the case of calculating the target object distance Lt in this embodiment. Further, as shown in Expression 1, the zoom lens group 11, so that the position change of the focus lens group 12 to be focused by the FB correction data X becomes a fixed value regardless of the zoom position Z or the target object distance Lt. Assume that the focus lens group 12 is disposed.

  Next, the process proceeds to S <b> 105, using the focus target position Ft and the focus position F calculated in S <b> 104, a drive signal for the focus lens group 12 is generated and output to the focus drive circuit 24. Since the process performed here is a general servo process, description is abbreviate | omitted. When the process of S105 ends, the process returns to S102. The processes of S102 to S105 show the focus control of the rear focus method. If the FB adjustment switch 20 is in the “normal mode”, these processes are repeatedly executed. By performing the processing in this manner, the focus operation position R and the object distance of the zoom lens apparatus 1 correspond one-to-one in the “normal mode”, and the object distance is kept constant in the case of only the zoom operation. The focal length can be operated as it is.

  On the other hand, if the FB adjustment switch 20 is in the “FB adjustment mode” in S102, the process proceeds to S106, and it is determined whether the focus operation ring 13 is operated using the signal from the focus operation ring position detector 21. To do. If the focus operation has been performed, the process proceeds to S107, and it is determined whether the zoom position Z is on the telephoto side or the wide-angle side with respect to the control switching zoom position Zx. When the zoom position Z is on the telephoto side from the control switching zoom position Zx, the process proceeds to S108 and S109.

  S108 and S109 are the same processes as S103 and S104, and the focus target position Ft is calculated. In S110, the zoom position Z and the focus target position Ft calculated in S109 are stored as telephoto side FB adjustment data Z1 and F1, respectively. Subsequently, the process proceeds to S105, where a drive signal for the focus lens group 12 is generated using the focus target position Ft and the focus position F calculated in S109, and is output to the focus drive circuit 24.

  When the zoom position Z is on the wide angle side with respect to the control switching zoom position Zx in S107, the process proceeds to S111. In S111, the focus target position Ft is calculated in the same manner as in S104 and S109. Here, the focus target position Ft is calculated using f2 (R) which is a function of only the focus operation position R. The function f2 (R) is expressed by the following equation 2.

  Rmax and Rmin shown here are values of the focus operation position R when the focus operation ring 13 is at the infinite end and the closest end, respectively. Fwmax and Fwmin indicate the maximum value and the minimum value of the focus position F that can be operated on the wide-angle side in the “FB adjustment mode”. These Fwmax and Fwmin are set so that the zoom lens apparatus 1 can always be focused within the range of the FB position and the subject distance allowed by the FB adjustment. Therefore, on the wide angle side of the control switching zoom position Zx, the focus target position Ft in a wider range than that in the “normal mode” is set by the operation of the focus operation ring 13.

  In S112, the zoom position Z and the focus target position Ft calculated in S111 are stored as wide-angle side FB adjustment data Z2 and F2, respectively. In S113, the subject distance Lp and the FB correction data X are calculated using the telephoto FB adjustment data Z1 and F1 stored in S110 and the wide-angle FB adjustment data Z2 and F2 stored in S112.

  The calculation method of the subject distance Lp and the FB correction data X is performed as follows. Assuming that the telephoto side FB adjustment data Z1 and F1 and the wide-angle side FB adjustment data Z2 and F2 are all in focus on the same subject, using Formula 1, Formula 3 and Formula Get 4.

  If the FB correction data X is deleted from these equations, Equation 5 is obtained.

  The subject distance Lp is calculated from this equation. At this time, since the function f1 (Z, Lt) uses a table, it is calculated by changing the subject distance Lp and finding a subject distance Lp that satisfies Equation 5. The FB correction data X is calculated using the subject distance Lp already calculated and Equation 3.

  In S114, the subject distance Lp calculated in S113 is set as the target object distance Lt. This is because when the zoom operation is performed thereafter, the object distance is set to the subject distance Lp regardless of the focus operation position R. Subsequently, the process proceeds to S105, and a drive signal for the focus lens group 12 is generated using the focus target position Ft and the focus position F calculated in S111, and is output to the focus drive circuit 24.

  If the focus operation is not performed in S106, the process proceeds to S115, and it is determined whether the zoom is operated using the zoom position Z. If the zoom is operated, the process proceeds to S116, and the focus target position Ft is calculated by the same processing as S104 and S109. If the zoom operation is not performed, the process proceeds to S117.

  In S117, it is determined whether or not the FB adjustment data X has been changed. If the FB adjustment data X has been changed, the process proceeds to S118 to overwrite the EEPROM 26 with the FB adjustment data X. Subsequently, the process proceeds to S <b> 105, where a drive signal for the focus lens group 12 is generated using the focus target position Ft and the focus position F, and is output to the focus drive circuit 24.

  FIGS. 4 to 6 show changes in the focus target position Ft in the software processing performed by the CPU 25 described above. FIG. 4 shows a change in the focus target position Ft in the “normal mode”. FIG. 5 shows a change in the focus target position Ft when the focus operation is performed in the “FB adjustment mode”. FIG. 6 shows a change in the focus target position Ft when the zoom operation is performed in the “FB adjustment mode”. C1, C2, and C3 in the figure indicate changes in the focus target position Ft when the focus operation ring is operated to the closest end, intermediate position, and infinite end position, respectively.

  As can be seen from FIG. 5, when the focus operation is performed in the “FB adjustment mode”, the focus target position Ft is set in the same manner as the “normal mode” on the telephoto side, and the “normal mode” is set on the wide angle side. A wider range can be set. On the other hand, when the zoom operation is performed, as shown in FIG. 6, the focus target position is calculated in the same manner as in the “normal mode” at any zoom position.

  FIG. 7 is a table showing the FB adjustment procedure in the zoom lens device 1 of the present embodiment. Since only the normal zoom lens device is operated except for operating the FB adjustment switch 20, FIG. It is easy to operate and FB adjustment can be easily performed.

  In order to explain the effect of this embodiment, a case will be considered in which the control method of the focus lens group is not switched according to the zoom position as in this embodiment, and the wide angle side is controlled in the same way as in the “normal mode”.

  C4, C5, and C6 in FIG. 8 indicate changes in the focus target position when the FB correction data is X1 and the focus operation ring is at the closest end, intermediate position, and infinite end, respectively. C7, C8, and C9 indicate changes in focus target positions corresponding to C4, C5, and C6 when the FB correction data is X2. Consider a case where the FB adjustment data before adjustment is X1, the FB adjustment data after adjustment is X2, and the subject distance at the time of adjustment corresponds to the object distance of C8.

  Since the FB adjustment data after adjustment is X2, and the subject distance at the time of adjustment corresponds to the object distance of C8, in order to focus on the subject at the telephoto end and the close end, the focus positions are the positions of Fp and Fq, respectively. Have to operate. However, if the FB adjustment data before adjustment is X1, the shaded portion in FIG. 8 is the operation range of the focus lens, so that the focus lens cannot be driven to the position Fq at the wide angle end, and the FB adjustment itself is performed. It becomes impossible.

  This is because, in the optical arrangement of a general rear focus type zoom lens device, the focus lens operation amount due to the object distance change is small near the wide-angle end, so that it becomes impossible to focus at the wide-angle end if the FB position shifts. Because there is.

  On the other hand, in this embodiment, as shown in FIG. 9, since the operating range of the focus lens is widened on the wide angle side, it is impossible to focus on the wide angle side as described above. In addition, on the telephoto side where the amount of operation of the focus lens due to the object distance change is large, the operation can be performed in the same manner as the normal operation, so that the operator can operate without a sense of incongruity.

  In this embodiment, when the zoom operation is performed without performing the focus operation in the “FB adjustment mode”, the object distance is kept constant on the wide angle side as in the “normal mode”. The focus target position is changed according to the zoom position. By performing the processing in this way, the object distance is not changed by the zoom operation even in the “FB adjustment mode”, and the operation can be performed more comfortably.

(Example 2)
The configuration of the rear focus zoom lens device 1 according to the second embodiment to which the present invention can be applied is the same as that shown in FIG. Here, only the software processing of the CPU 25 different from the first embodiment will be described. FIG. 10 is a flowchart of software processing performed by the CPU 25 in this embodiment, and only S151, S152, and S153 that are different from the first embodiment will be described.

  S151 and S152 are always executed before S105, and the current focus operation position R is set as the focus operation reference position Rc, and the focus target position Ft calculated in S116 is set as the focus reference position Fc. S153 is executed when the FB adjustment switch 20 is in the “FB adjustment mode”, the focus operation is performed, and the zoom position Z is on the wide angle side with respect to the control switching zoom position Zx. FIG. 11 is a flowchart showing in detail the focus target position Ft calculation process performed in S153.

  In S201, it is determined whether the focus operation ring 13 is operated from the focus operation position R to the infinite side or the closest side. When it is operated to the infinite side, the process proceeds to S202, and it is determined whether f3 (Rmax) calculated using the function f3 (R) expressed by the following Expression 6 is larger than Fwmax.

  When f3 (Rmax) is larger than Fwmax, the focus target position Ft is set to f3 (R) calculated using the focus operation position R. When f3 (Rmax) is equal to or less than Fwmax, the focus target position Ft is set to f4 (R) using the function f4 (R) and the focus operation position R expressed by the following Expression 7.

  In S205, it is determined whether the focus target position Ft calculated in S203 or S204 is larger than Fwmax. If it is larger, the focus target position Ft is reset to Fwmax in S206.

  If it is determined in S201 that the focus operation ring 13 has been operated to the close side, the process proceeds to S207, where it is determined whether f3 (Rmin) calculated using the function f3 (R) is less than Fwmin. When f3 (Rmin) is less than Fwmin, the focus target position Ft is set to f3 (R) calculated using the focus operation position R. When f3 (Rmin) is equal to or greater than Fwmin, the focus target position Ft is set to f5 (R) using the function f5 (R) and the focus operation position R expressed by the following Expression 8.

  In S210, it is determined whether or not the focus target position Ft calculated in S208 or S209 is smaller than Fwmin. If it is smaller, the focus target position Ft is reset to Fwmin in S211.

  When the focus target position Ft is calculated as described above, how the focus target position Ft changes with respect to the focus operation position R will be specifically described. FIG. 12 is a diagram illustrating an example of the relationship between the focus operation position R and the focus target position Ft in the calculation of the focus target position Ft performed in S153.

  When the focus operation position R is operated in an infinite direction from P1 in FIG. 12, it is determined whether or not f3 (Rmax) is larger than Fwmax in S202. Since the function f3 (R) passes through P1 and shows a straight line having a slope of (Fwmax−Fwmin) / (Rmax−Rmin), f2 (Rmax) indicates Fs1. Therefore, in this example, f3 (Rmax) is larger than Fwmax, and the focus target position Ft is calculated in S203. The straight line Q1 is a straight line on the function f3 (R), and the focus target position Ft is calculated according to this straight line.

  Subsequently, when P2 is reached, since f3 (R) exceeds Fwmax, the focus target position Ft is fixed to Fwmax by the process of S206. Accordingly, the focus target position Ft is calculated as shown by the straight line Q2, and even if the focus operation position R is operated in an infinite direction, the focus target position Ft does not change.

  Next, when the focus operation position R is operated to the closest side at P3 before the focus operation position R reaches Rmax, the process proceeds to S207, where it is determined whether f3 (Rmin) is smaller than Fwmin. In this case, since the function f3 (R) passes through P3 and shows a straight line having a slope of (Fwmax−Fwmin) / (Rmax−Rmin), f3 (Rmin) indicates Fs2.

  Accordingly, in this example, f3 (Rmin) is equal to or greater than Fwmin, and the focus target position Ft is calculated in S209. The function f5 (R) indicates a straight line Q3 connecting P3 and P4, and Ft is calculated so that the focus target position Ft when the focus operation position R is set to Rmin is Fwmin.

  In the case of the first embodiment, the focus target position Ft may change greatly at the moment of step 4 to step 5 of the FB adjustment procedure shown in FIG. This is because the continuity of the focus target position Ft is not considered in the first embodiment when the calculation of the focus target position Ft is switched from S116 to S111. For this reason, the operator may feel a sense of discomfort because the object distance changes greatly only by slightly operating the focus operation ring 13 in the procedure 5 of the FB adjustment procedure shown in FIG.

  On the other hand, in the second embodiment, when the calculation of the focus target position Ft is switched from S116 to S153, the focus target position Ft is the focus reference position Fc in both processes and is not discontinuous. Therefore, even if the operator operates the focus operation ring 13 in the procedure 5 of the FB adjustment procedure shown in FIG. 7, the object distance changes continuously, and the operator does not feel uncomfortable.

  Further, by calculating the focus target position Ft as shown in the flowchart of FIG. 11, the focus target position Ft is operated from Fwmin to Fwmax regardless of the focus operation reference position Rc set in S151. be able to. Therefore, as in the first embodiment, it is impossible that the subject cannot be focused when the zoom position is on the wide angle side during FB adjustment.

1 zoom lens device, 11 zoom lens group, 12 focus lens group,
13 focus operation ring, 16 focus motor, 20 FB adjustment switch,
22 zoom position detector, 23 focus position detector, 24 focus drive circuit,
25 CPU, 26 EEPROM

Claims (8)

Zoom means for changing the focal length, zoom position detection means for detecting the zoom position, focus means for changing the object distance, focus position detection means for detecting the focus position, and focus drive means for electrically driving the focus means FB adjustment for storing a focus operation means for rotating the focus means whose rotation range is mechanically limited, and a flange back correction value for correcting the position of the focus means according to the flange back position In a rear focus optical device having a value storage means, and a focus target position calculation means for calculating a focus target position of the focus means from the zoom position, the operation position of the focus operation means, and the flange back correction value.
Mode switching means for switching between the first mode and the second mode;
The focus target position calculation means calculates the focus target position similar to the first mode when the zoom position is on the telephoto side with respect to the predetermined position in the second mode, In addition, when the zoom position is on the wide angle side from the predetermined position, the focus target position is calculated so that the focus target position can be set in a wider range than in the first mode.   The focus target position calculating means is independent of the zoom position and the flange back correction value when the zoom position is on the wide-angle side of the predetermined position in the second mode, and the focus operation means The optical apparatus according to claim 1, wherein the focus target position is calculated from only the operation position.   Focus operation determination means for determining whether or not the focus operation means is operated, and in the second mode, the zoom position is on the telephoto side from a predetermined position, and the focus operation means is operated In this case, the zoom position and the focus position are stored as flange back adjustment first information, and in the second mode, the zoom position is on the wide-angle side from a predetermined position, and the focus operation means is operated. A flange back adjustment storage means for storing the zoom position and the focus position as flange back adjustment second information, and calculating the flange back correction value from the flange back adjustment first information and the flange back adjustment second information. 3. The flange back correction value calculating means for performing the processing according to claim 1 or claim 2. Optical device.   The focus target position calculation means prevents the focus target position from changing discontinuously when the zoom position is switched from the telephoto side to the wide angle side with respect to the predetermined position in the second mode. 4. The optical apparatus according to claim 1, wherein a focus target position is calculated.   A focus operation determination unit that determines whether or not the focus operation unit is operated; and a zoom operation determination unit that determines whether or not the zoom unit is operated from the zoom position, and the focus target position calculation unit includes: When the focus operation unit is not operated and the zoom unit is operated in the second mode, the focus target similar to the first mode is used regardless of the zoom position. The optical apparatus according to claim 4, wherein the position is calculated.   Focus reference position storage means for storing the focus target position as a focus reference position, and storing the focus operation position as a focus operation reference position, wherein the focus target position calculation means is in the second mode, and 5. The focus target position is calculated from the focus operation position, the focus reference position, and the focus operation reference position when the zoom position is on the wide angle side from the predetermined position. 5. The optical device according to 5.   The focus target position calculation means sets the focus target position so that the focus target position is set to a constant range in the entire operation range of the focus operation means regardless of the focus reference position or the focus operation reference position. The optical device according to claim 6, wherein the optical device is calculated.   8. The normal operation is performed in the first mode, and the second mode is a mode for changing the flange back correction value. 8. Optical device.