JP5135813B2 - Optical system drive device and camera - Google Patents

Description

  The present invention relates to an optical system driving device and a camera.

  A technique for moving a focus lens having a focus adjustment function during zooming with a zoom lens is known (see Patent Document 1).

JP-A-5-150153

  According to the prior art, there is a problem that it may be difficult to control the movement of the focus lens following the movement of the zoom lens.

An optical system driving apparatus according to a first aspect of the present invention includes a first driving unit that moves the zoom lens in the optical axis direction, a second driving unit that moves the focus lens in the optical axis direction, and a zoom operation that is continuously issued. Moving the zoom lens and the focus lens for a first predetermined time by a zoom lens movement amount and a focus lens movement amount determined based on the position of the zoom lens and the position of the focus lens at the time of signal generation, When the generation of the zoom operation signal continues at a predetermined timing before the end of the first predetermined time, the zoom lens and the focus lens at the end of the first predetermined time The zoom lens is moved in the second predetermined time by the zoom lens moving amount and the focus lens moving amount determined based on the zoom lens. And the focus lens so as to move respectively, characterized in that it comprises a control means for controlling said first drive means and second drive means.

  According to the present invention, it is possible to appropriately control movement of the two optical systems.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining a main configuration of an electronic camera 1 according to an embodiment of the present invention. The electronic camera 1 is controlled by the CPU 12.

  The photographic lens 26 includes a focus lens group 21 and a zoom lens group 20, and forms a subject image on the imaging surface of the imaging element 22. The imaging element 22 is configured by a CCD image sensor or the like, captures a subject image on the imaging surface, and outputs an imaging signal to the imaging circuit 23.

  The zoom lens driving device 17 moves the zoom lens group 20 forward and backward in the optical axis direction according to an instruction from the CPU 12. As a result, zoom adjustment by the photographing lens 26 is performed. The CPU 12 sends an instruction to move the zoom lens group 20 to the zoom lens driving device 17 when an operation signal indicating that the zoom switch 16 a or 16 b constituting the operation member 16 is operated is input. The zoom switch 16a is a switch for zooming to the wide side (wide angle side), and the zoom switch 16b is a switch for zooming to the telephoto side (telephoto side).

  The focus lens driving device 18 moves the focus lens group 21 forward and backward in the optical axis direction in response to an instruction from the CPU 12. Thereby, the focus adjustment by the photographing lens 26 is performed. The CPU 12 acquires contrast information called a focus evaluation value using an image pickup signal from the image pickup device 22 and sends an instruction to move the focus lens group 21 to the focus lens driving device 18 so as to maximize the focus evaluation value. Further, when the focal plane of the photographic lens 26 moves due to the zoom adjustment described above, the CPU 12 moves the focus lens group 21 forward and backward in the optical axis direction so as to correct this movement amount.

  The imaging circuit 23 performs predetermined analog processing (such as gain control) and converts an analog imaging signal into digital data using a built-in A / D conversion circuit.

  The CPU 12 inputs a signal output from each block, performs a predetermined calculation, and outputs a control signal based on the calculation result to each block. The CPU 12 includes an image processing circuit, and performs image processing on the digital image signal input from the imaging circuit 23. The image processing includes, for example, contour enhancement, color temperature adjustment (white balance adjustment) processing, and format conversion processing for an image signal.

  The buffer memory 13 temporarily stores data before and after image processing and during image processing, and stores an image file before recording on a recording medium 30 described later, and stores an image file read from the recording medium 30. Used to The display image creation circuit 14 creates display data for displaying the captured image on the liquid crystal monitor 15.

  The recording medium 30 includes a memory card that can be attached to and detached from the electronic camera 1. The recording medium 30 records captured image data and an image file including the information in accordance with an instruction from the CPU 12. The image file recorded on the recording medium 30 can be read by an instruction from the CPU 12. The operation member 16 includes various buttons and switches of the electronic camera 1. For example, an operation signal corresponding to the operation content of each operation member, such as an operation of the half-press switch 16c or the full-press switch 16d that is turned on in conjunction with the release button pressing operation, and the zoom switches 16a and 16b described above is output to the CPU 12. To do.

<Shooting operation>
When the operation signal indicating the half-press operation of the release button is input from the half-press switch 16c, the CPU 12 starts photometry. In photometry, the image sensor 22 performs photometry imaging, and the brightness information of the object scene is acquired from the signal value of the imaging signal output after charge accumulation. Further, the CPU 12 performs an exposure calculation based on the brightness information and determines an exposure condition.

  In addition, the CPU 12 acquires the above-described focus evaluation value using the imaging signal from the imaging element 22, and moves the focus lens group 21 based on the evaluation value to perform autofocus adjustment.

  When the operation signal indicating the full press of the release button is input from the full press switch 16d following the half press operation signal, the CPU 12 starts the photographing operation. Specifically, the image pickup device 22 is made to accumulate charge for photographing under the determined exposure conditions. The image pickup circuit 23 performs the above-described signal processing on the image pickup signal output from the image pickup element 22 after accumulating charge for photographing. The image processing circuit 12 further performs signal processing, the processed image data is recorded on the recording medium 30, and the captured image is displayed on the monitor 15.

<Through image display>
The electronic camera 1 causes the monitor 15 to display an image captured by the image sensor 22 before starting the photographing operation. By causing the image sensor 22 to repeatedly capture images and sequentially displaying the latest captured images on the monitor 15, the subject image can be displayed in real time. As a result, the user can confirm the change in magnification during zoom adjustment and the state of focus adjustment from the image displayed on the monitor 15.

  This embodiment is characterized by lens driving (particularly lens driving during zoom adjustment) performed by the electronic camera 1 described above, and will be further described focusing on this point.

  Each of the zoom lens driving device 17 and the focus lens driving device 18 moves the lens back and forth using a stepping motor as a driving source. That is, the zoom lens driving device 17 controls the rotation of the stepping motor for driving the zoom lens to move the zoom lens group 20 forward and backward in the optical axis direction, and the focus lens driving device 18 controls the rotation of the stepping motor for driving the focus lens. The focus lens group 21 is moved forward and backward in the optical axis direction.

<Focus lens drive>
1. At the time of focus adjustment The CPU 12 instructs the focus lens driving device 18 to move the focus lens group 21 necessary for focusing at the time of focus adjustment. The focus lens driving device 18 in this case has the number of pulse signals given to the stepping motor to move the movement amount of the focus lens group 21 instructed by the CPU 12 at a predetermined focus lens moving speed, and the cycle of the pulse signals. (Pulse frequency) is determined. The number of pulse signals corresponds to the rotation angle of the stepping motor (that is, the movement amount of the focus lens group 21), and the pulse signal cycle corresponds to the rotation speed of the stepping motor (that is, the movement speed of the focus lens group 21).

2. At the time of zoom adjustment The CPU 12 instructs the focus lens driving device 18 of the amount of movement of the focus lens group 21 necessary for correction accompanying the zoom adjustment at the time of zoom adjustment and the time used for the movement of the focus lens group 21. The focus lens driving device 18 in this case uses the number of pulse signals to be given to the stepping motor so as to move the focus lens group 21 using the time instructed by the CPU 12 and the period (pulse frequency) of the pulse signals. decide. In the case of the present embodiment, the moving speed of the focus lens group 21 at the time of zoom adjustment is controlled to be lower than its maximum speed (maximum focus speed).

<Zoom lens drive>
The CPU 12 instructs the zoom lens driving device 17 on the amount of movement of the zoom lens group 20 during zoom adjustment every predetermined time ΔT. The zoom lens driving device 17 sends the number of pulse signals to the stepping motor so as to move the zoom lens group 20 during the movement time (corresponding to the time ΔT) instructed by the CPU 12, and the period (pulse frequency) of the pulse signals. To decide.

  FIG. 2 is a diagram for explaining lens driving during zoom adjustment. In FIG. 2, the horizontal axis represents time. The vertical axis represents the zoom operation signal waveform, the zoom lens position, and the focus lens position in order from the top. At time t0, an operation signal is input from the zoom switch 16a or 16b to the CPU 12 (the signal level becomes L level). The inclination of the line segment (arrow) in the figure represents the moving speed of each lens. The deeper the inclination angle, the higher the speed, and the shallower the inclination angle, the lower the speed.

  The CPU 12 moves the zoom lens group 20 at time ΔT (1) based on the zoom switch (16a or 16b) that issued the zoom operation signal, the zoom lens position Z1 at time t0, and the focus lens position F1 at time t0. ΔZ (1) and the movement amount ΔF (1) of the focus lens group 21 are determined. The time ΔT (1) corresponds to ΔZ (1) / (maximum zoom speed).

  In general, since the imaging surface of the photographic lens 26 moves with zoom adjustment, the focus lens group 21 is moved and corrected in order to maintain the in-focus state. Since this correction amount is known from the design information of the photographic lens 26, the movement amount ΔF of the focus lens group 21 can be obtained by storing in advance in the CPU 12 as table data using the zoom lens position and the focus lens position as arguments. Can be read from table data. When the zoom lens group 20 is moved by [Delta] Z by zoom adjustment after focusing, if the focus lens group 21 is moved by [Delta] F according to the table value, the image is taken before zoom adjustment, during zoom adjustment, and after zoom adjustment. The in-focus state by the lens 26 is maintained.

  The CPU 12 sends the determined movement amount ΔZ (1) and movement amount ΔF (1) to the zoom lens driving device 17 and the focus lens driving device 18 together with the time ΔT (1), respectively.

  As illustrated in FIG. 2, the movement amount ΔF of the focus lens group 21 depends on the position of the focus lens (specifically, when the subject close to the electronic camera 1 is focused and when the subject is far from the electronic camera 1). It ’s different) Therefore, the focus lens driving device 18 controls the moving speed of the focus lens group 21 every time ΔT so as to move the focus lens group 21 by using the moving time (ΔT) instructed by the CPU 12 to the full.

  At time t1 in FIG. 2, the zoom lens driving device 17 controls the stepping motor to move the zoom lens group 20 from the position Z1 to the position Z2 at the maximum zoom speed at the time ΔT (1) instructed from the CPU 12 ( The amount of movement is ΔZ (1)). At the same time, the focus lens driving device 18 controls the stepping motor so as to move the focus lens group 21 from the position F1 to the position F2 using the time ΔT (1) instructed from the CPU 12 to the full (the movement amount is ΔF (1 )).

  The CPU 12 checks the zoom operation signal at a predetermined timing before the time ΔT (1) ends, and when the operation signal is continued, the zoom lens position Z2 and the focus lens position F2 at the time ΔT (1) end. Based on the above, the movement amount ΔZ (2) of the zoom lens group 20 and the movement amount ΔF (2) of the focus lens group 21 at time ΔT (2) are determined. Time ΔT (2) corresponds to ΔZ (2) / (maximum zoom speed). The CPU 12 sends the determined movement amount ΔZ (2) and movement amount ΔF (2) to the zoom lens driving device 17 and the focus lens driving device 18 together with the time ΔT (2), respectively.

  At time t2, the zoom lens driving device 17 controls the stepping motor to move the zoom lens group 20 from the position Z2 to the position Z3 at the maximum zoom speed at the time ΔT (2) instructed from the CPU 12 (the amount of movement is ΔZ (2)). At the same time, the focus lens driving device 18 controls the stepping motor so as to move the focus lens group 21 from the position F2 to the position F3 by using the time ΔT (2) instructed from the CPU 12 to the full extent (the movement amount is ΔF (2 )).

  The same applies after time ΔT (3). As described above, when the operation signal is continued, the zoom lens group 20 is largely moved by stacking the time ΔT (ΔT (1) + ΔT (2) + ΔT (3) +,..., + ΔT (n)).

  The CPU 12 checks the zoom operation signal at a predetermined timing before the time ΔT (4) ends, and when the operation signal is not input, the movement of the zoom lens group 20 and the focus lens group after the time ΔT (4) ends. The movement of 21 is stopped.

  Note that the CPU 12 changes the movement direction of the zoom lens group 20 when an operation signal is input from the zoom switch 16a and when an operation signal is input from the zoom switch 16b.

  Further, the driving direction of the focus lens group 21 may be different from that illustrated in FIG. 2 depending on the characteristics of the photographing lens 26 or the zoom lens position Zn and the focus lens position Fn.

  In FIG. 2, it appears that there is an interval between the end of the time ΔT (n−1) and the start of the next time ΔT (n). However, the control may be performed without any interval. In consideration of the time for calculating the necessary movement amount ΔZ (n) of the zoom lens group 20 and the movement amount ΔF (n) of the focus lens group 21 at the next time ΔT (n), whether or not the zoom operation signal is continued is appropriately determined. By checking at a proper timing, the time ΔT (n) can be started immediately after the time ΔT (n−1) ends.

  In the present embodiment, the moving time of the focus lens group 21 is matched with the moving time of the zoom lens group 20, but when the moving time of the focus lens group 21 is longer than the moving time of the zoom lens group 20, the zoom lens The movement time of the group 20 may be moved to match the movement time of the focus lens group 21.

According to the embodiment described above, the following effects can be obtained.
(1) Since the movement control for the zoom lens group 20 is repeated every time ΔT and the movement control for the focus lens group 21 is repeated every time ΔT, the zoom magnification is changed (the movement amount of the zoom lens group 20). Accordingly, even when the necessary focus correction amount (the movement amount of the focus lens group 21) is different, the movement amount ΔF of the focus lens group 21 can be appropriately controlled every time ΔT.

(2) When the focus lens group 21 and the zoom lens group 20 are moved at their respective maximum speeds, the time required to move the focus lens group 21 is shorter than the time ΔT required to move the zoom lens group 20 (in other words, For example, if the focus lens group 21 is moved at the maximum focus speed, the movement amount ΔF required for the focus lens group 21 is exceeded.) Therefore, the movement speed of the focus lens group 21 is adjusted according to the movement time ΔT of the zoom lens group 20. Controlled to low speed. During the time ΔT, the focus lens group 21 is continuously moved to move the movement amount ΔF, so that the focus is substantially maintained throughout the time ΔT in which the zoom magnification changes. By focusing before zooming, an image that is almost in focus can be obtained before zoom adjustment and during zoom adjustment.

(3) Since the zoom lens group 20 is moved at the maximum zoom speed during the time ΔT, the time required for lens movement can be shortened compared to when the zoom maximum speed is not used.

(Modification 1)
In the above description, the case where ΔT (1) = ΔT (2) = ΔT (3). If the amount ΔF to move the focus lens group 21 is large and ΔF cannot be moved within the time ΔT, the CPU 12 extends ΔT to ΔTL as follows.

  The CPU 12 determines the time ΔT based on the zoom lens position Z (n) and the focus lens position F (n) at the time t0, or when the movement of the lens group is being performed, at the end of the time ΔT (n−1). The movement amount ΔZ (n) of the zoom lens group 20 and the movement amount ΔF (n) of the focus lens group 21 in (n) are determined. When ΔF (n) satisfies ΔF (n)> (maximum focus speed) × ΔT (n), the CPU 12 extends ΔT to ΔTL. However, ΔTL = ΔF (n) / (maximum focus speed).

  The CPU 12 sends the movement amount ΔZ (n) and the movement amount ΔF (n) to the zoom lens driving device 17 and the focus lens driving device 18 together with the time ΔTL. In this case, the zoom lens driving device 17 continues to move the zoom lens group 20 for the extension time ΔTL instructed by the CPU 12 so as to move the zoom lens group 20 from the position Z (n) to the position Z (n + 1). The stepping motor is controlled (movement amount is ΔZ (n)). Since the time TL is extended, the rotation speed of the stepping motor that drives the zoom lens group 20 (that is, the moving speed of the zoom lens group 20) is controlled to be lower than the maximum zoom speed.

  On the other hand, the focus lens driving device 18 continues the movement of the zoom lens group 20 for the extension time ΔTL instructed by the CPU 12 to step the focus lens group 21 from the position F (n) to the position F (n + 1). The motor is controlled (movement amount is ΔF (n)). The rotation speed of the stepping motor that drives the focus lens group 21 (that is, the moving speed of the focus lens group 21) is controlled to the maximum focus speed.

  According to the first modification, when the amount ΔF to be moved by the focus lens group 21 is too large and ΔF cannot be moved within the time ΔT, the movement time of the zoom lens group 20 is changed to ΔTL longer than ΔT. Unlike the case where it takes longer than the movement time of the group 21, even when the movement time of the focus lens group 21 is longer than the movement time of the zoom lens group 20, the lens group whose movement time is shorter in accordance with the longer movement time. The moving speed of the lens groups 20 and 21 can be made uniform by controlling the moving speed of the lens group 20 to a low speed. In addition, since the focus lens group 21 is moved at the maximum focus speed at the time ΔTL, the time required for moving the lens can be shortened compared to the case where the focus maximum speed is not used.

(Modification 2)
Although an example in which a stepping motor is used as a driving source for moving the lens forward and backward has been described, a DC motor may be used instead of the stepping motor.

(Modification 3)
Although the electronic camera 1 has been described as an example for confirming the magnification change and the focus adjustment state during zoom adjustment from the image displayed on the monitor 15, the magnification change and the focus adjustment state during zoom adjustment are optically observed. The present invention may also be applied to.

(Modification 4)
For example, in the case of a single-lens reflex camera that obtains an observation image using a part of the light beam that has passed through the photographing lens 26, the present invention can be applied not only to an electronic camera but also to a silver salt camera.

(Modification 5)
The present invention may be applied not only to a camera but also to an observation device such as a telescope including an observation optical system having a zoom lens group 20 and a focus lens group 21.

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

1 is a block diagram of an electronic camera according to an embodiment of the present invention. It is a figure explaining the lens drive at the time of zoom adjustment.

Explanation of symbols

1 ... Electronic camera 12 ... CPU
17 ... Zoom lens driving device 18 ... Focus lens driving device 20 ... Zoom lens group 21 ... Focus lens group

Claims (6)

First driving means for moving the zoom lens in the optical axis direction;
Second driving means for moving the focus lens in the optical axis direction;
The zoom lens and the focus lens move amount determined based on the position of the zoom lens and the position of the focus lens when the zoom operation signal that is continuously issued is generated and the focus lens move amount in the first predetermined time Each of the focus lenses is moved, and when the generation of the zoom operation signal continues at a predetermined timing before the end of the first predetermined time, the position of the zoom lens at the end of the first predetermined time The first drive means and the second drive are configured to move the zoom lens and the focus lens, respectively, for a second predetermined time by a zoom lens movement amount and a focus lens movement amount determined based on the position of the focus lens. Control means for controlling the means, and an optical system driving device characterized by comprising: The optical system driving device according to claim 1,
The optical system driving apparatus characterized in that the control means moves at least one of the zoom lens and the focus lens at the maximum speed during the first or second predetermined time. In the optical system drive device according to claim 1 or 2,
Wherein if the first or second of the focus lens in a predetermined time exceeding the amount of movement required is moved at the maximum speed of the focus lens, the focus lens is moved at a lower speed than the maximum speed An optical system drive device characterized by the above. In the optical system drive device according to claim 1 or 2,
Wherein if a shortage of the first or second of the focus lens in a predetermined time the amount of movement necessary to move at the maximum speed of the focus lens, longer than the first or second predetermined time the focus lens over an extended predetermined time is moved in the highest speed, the optical system driving device according to claim the zoom lens in the extended predetermined time to move at a lower speed than the maximum speed of the zoom lens. In the optical system drive device according to any one of claims 1 to 4 ,
The optical system drive device, wherein the control means controls the first drive means and the second drive means so as to maintain a focus adjustment state during zoom adjustment by the zoom lens . A camera comprising the optical system driving device according to any one of claims 1 to 5 .

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