JP2010243876A - Optical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately detect the position of a movable member without using an absolute position detector. <P>SOLUTION: Optical equipment includes: an operation member 35 which is operated to move a first optical element 2; a moving amount detecting means 105 comprising a scale 20 and a moving amount sensor 24 which move relative to each other, for detecting the moving amount of the movable member as one of the first optical element, the operation member and a driving member 31 for driving the first optical element in accordance with the operation of the operation member; a holding member 23 for holding the scale or the moving amount sensor; an actuator 120 for moving the holding member; and reset detecting means 25, 26 and 118 for detecting that the holding member is moved by the actuator to a predetermined reset position with respect to the movable member. The position of the movable member is detected using the moving amount from the reset position detected by the moving amount detecting means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an optical apparatus such as a digital still camera, a video camera, and an interchangeable lens, and in particular, an optical device having a detector that detects the position of a movable optical element or an operation member operated to move the optical element. Regarding equipment.

An optical apparatus having an optical element such as a lens and an operation member operated to move the optical element is disclosed in Patent Document 1.
This optical apparatus includes an absolute position detector that detects an absolute position of an optical element and an operation member (hereinafter referred to as a movable member), a movement amount (relative position) detector that detects a movement amount (relative position), and a movable member. And a reset detector for detecting that has moved to a predetermined reset position. In the optical apparatus, the absolute position detector is used to detect the position of the movable member until the reset detector detects that the movable member has moved to the reset position. Then, when it is detected that the operation member has been operated and the movable member has moved to the reset position, the position of the movable member is detected (calculated) using the movement amount detected by the movement amount detector.

JP 2006-259520 A

In the optical apparatus disclosed in Patent Document 1, after detecting that the movable member has moved to the reset position, the position of the movable member can be accurately detected from the movement amount detected by the movement amount detector. it can.
However, the absolute position detector used until the movement of the movable member to the reset position is detected generally has a lower position detection accuracy than the relative position detector. For this reason, if the position (movement) of the optical element is controlled using the position detected by the absolute position detector, a very high position control accuracy of the optical element cannot be obtained.
For example, in some optical devices capable of zooming, control is performed to move the focus lens by an actuator in order to correct the image plane movement accompanying the zooming operation. The position of the focus lens is determined according to the subject distance and the position of the zoom lens.
However, if the position of the variable magnification lens is detected using an absolute position detector and the movement of the focus lens is controlled based on the detected position, the focal point shifts due to the low position detection accuracy of the variable magnification lens. May occur.
The present invention provides an optical apparatus that can accurately detect the position of a movable member without using an absolute position detector.

An optical apparatus according to one aspect of the present invention includes a movable first optical element, an operation member operated to move the first optical element, a relative moving scale, and a movement amount sensor. A movement amount detecting means for detecting a movement amount of a movable member that is one of the first optical element, the operation member, and a drive member that drives the first optical element in accordance with the operation of the operation member; A holding member that holds the scale or the movement amount sensor, an actuator that moves the holding member, and a reset detection unit that detects that the holding member has been moved to a predetermined reset position with respect to the movable member by the actuator. And the position of a movable member is detected using the movement amount from the reset position detected by the movement amount detection means.

In the present invention, the movement amount detecting means is reset by moving the holding member holding the scale or the movement amount sensor to the reset position with respect to the movable member by the actuator. Thereby, the position of the movable member can be detected using the movement amount detected by the movement amount detection means from the reset position. Accordingly, it is possible to detect the position of the movable member with good accuracy without using an absolute position detection unit that is generally lower in detection accuracy than the movement amount detection unit. Moreover, in the present invention, since it is not necessary to operate the operating member in order to move the holding member to the reset position, the holding member can be moved to the reset position even when the operating member is stopped by hand. it can.

1 is a side cross-sectional view of an optical apparatus that is Embodiment 1 of the present invention. FIG. 3 is a front sectional view of the optical apparatus according to the first embodiment. FIG. 3 is a block diagram illustrating an electrical configuration of the optical apparatus according to the first embodiment. 6 is a flowchart illustrating an initial position setting operation in the optical apparatus according to the first embodiment. 5 is a flowchart showing detailed processing in a part of the flowchart shown in FIG. 4. Side surface sectional drawing of the optical apparatus which is Example 2 of this invention. FIG. 6 is a front sectional view of an optical apparatus according to a second embodiment. FIG. 6 is a block diagram illustrating an electrical configuration of an optical apparatus according to a second embodiment. 9 is a flowchart illustrating an initial position setting operation in the optical apparatus according to the second embodiment. The flowchart which shows the detailed process in a part of flowchart shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a side sectional view of a lens barrel portion of a video camera as an optical apparatus that is Embodiment 1 of the present invention. FIG. 2 shows a cross section (front cross section) of the lens barrel when viewed in the optical axis direction.
Reference numeral 1 denotes a fixed first lens unit. Reference numeral 2 denotes a second lens unit (variable lens unit: first optical element) that moves in the optical axis direction for variable magnification. Reference numeral 3 denotes a fixed third lens unit. Reference numeral 4 denotes a fourth lens unit (focus lens unit: second optical element) that moves in the direction of the optical axis in order to correct image plane fluctuations accompanying zooming and focus adjustment. Reference numeral 5 denotes a fixed diaphragm. The first lens unit 1 to the fourth lens unit 4 and the diaphragm 5 constitute an imaging optical system.
Reference numeral 6 denotes a rear frame attached to a camera body (not shown). Reference numeral 7 denotes a front frame attached to the rear frame 6. Reference numeral 8 denotes a first lens frame that holds the first lens unit 1 and is fixed to the front frame 7. Reference numeral 9 denotes a third lens frame that holds the third lens unit 3 and is fixed to the rear frame 6.
Reference numerals 10 and 11 denote guide bars which extend in the optical axis direction and whose both ends are held by the rear frame 6 and the third lens frame 9. Reference numeral 12 denotes a fourth lens frame that holds the fourth lens unit 4 and is engaged with the guide bars 10 and 11 so as to be movable in the optical axis direction. The fourth lens frame 12 is guided in the optical axis direction by the guide bar 10 and is prevented from rotating around the guide bar 10 by the guide bar 11.
Reference numeral 13 denotes a first coil fixed to the fourth lens frame 12. Reference numeral 14 denotes a first yoke fixed to the rear frame 6. Reference numeral 15 denotes a second yoke fixed to the front end of the first yoke 14. Reference numeral 16 denotes a first magnet fixed to the first yoke 14. The first coil 13, the first and second yokes 14, 15 and the first magnet 16 constitute a fourth lens actuator as a linear electromagnetic actuator. The fourth lens actuator generates a thrust in the optical axis direction by energizing the first coil 13, and moves the fourth lens frame 12 in the optical axis direction.
Reference numerals 17 and 18 denote guide bars which extend in the optical axis direction and whose both ends are held by the rear frame 6 and the first lens frame 8. Reference numeral 19 denotes a second lens frame that holds the second lens unit 2 and engages the guide bars 17 and 18 so as to be movable in the optical axis direction. The second lens frame 19 is guided in the optical axis direction by the guide bar 17 and is prevented from rotating around the guide bar 17 by the guide bar 18. The second lens frame 19 constitutes a movable member together with the second lens unit 2.
Reference numeral 20 denotes a scale fixed to the second lens frame 19. Reference numerals 21 and 22 denote guide bars that extend in the optical axis direction and whose both ends are held by the third lens frame 9 and the first lens frame 8. Reference numeral 23 denotes a sensor frame (holding member) engaged with the guide bars 21 and 22 so as to be movable in the optical axis direction. The sensor frame 23 is guided in the optical axis direction by the guide bar 21 and is prevented from rotating around the guide bar 21 by the guide bar 22.
Reference numeral 24 denotes a movement amount sensor arranged to face the scale 20. The movement amount sensor 24 and the scale 20 move relative to each other to constitute a second lens encoder as movement amount detection means (relative position detection means) for detecting the relative movement amount (relative position). The movement amount sensor 24 is held by the sensor frame 23 and moves in the optical axis direction together with the sensor frame 23.
The scale 20 is composed of magnets magnetized at a predetermined pitch, and the movement amount sensor 24 is composed of MR sensors. The MR sensor outputs an electrical signal corresponding to a change in magnetism accompanying movement with respect to the scale 20.
However, the scale 20 may be provided with a reflection pattern that reflects light at a predetermined pitch, and the movement amount sensor 24 may be configured by a photo reflector that irradiates the reflection pattern with light and outputs an electrical signal corresponding to the reflected light. .
Reference numerals 25 and 26 denote photo-interrupters as reset detecting means fixed at two positions apart in the optical axis direction (movement direction of the sensor frame 23) in the sensor frame 23, respectively. The photo interrupter 25 is disposed closer to the subject side (front side) in the optical axis direction than the photo interrupter 26.
Each of the photo interrupters 25 and 26 has a light emitting part and a light receiving part. In each photo interrupter, the light shielding part 19a formed in the second lens frame 19 enters between the light emitting part and the light receiving part and blocks the detection light directed from the light emitting part to the light receiving part, whereby the sensor frame 23 becomes the second lens. It is detected that the frame 19 has been moved to a predetermined reset position. Hereinafter, the reset position of the sensor frame 23 is referred to as a sensor frame reset position.
Reference numeral 27 denotes a third yoke fixed to the front frame 7. Reference numeral 28 denotes a fourth yoke fixed to the front end of the third yoke. Reference numeral 29 denotes a second coil attached to the third yoke 27. Reference numeral 30 denotes a second magnet attached to the sensor frame 23. The third and fourth yokes 27 and 28, the second coil 29, and the second magnet 30 constitute a sensor frame actuator as a linear electromagnetic actuator. When the second coil 29 is energized, the sensor frame actuator generates a thrust in the optical axis direction and moves the sensor frame 23 in the optical axis direction. When the rear end portion of the second magnet 30 abuts against the stopper portion 27a of the third yoke 27, the moving end of the sensor frame 23 on the rear side in the optical axis direction is determined.
A cam ring 31 is arranged on the outer periphery of the front frame 7 so as to be rotatable around the optical axis. The cam ring 31 is sandwiched between the front frame 7 and the first lens frame 8 and is prevented from moving in the optical axis direction. A cam groove portion (not shown) is formed in the cam ring 31, and a cam follower (not shown) attached to the second lens frame 19 is engaged with the cam groove portion. When the cam ring 31 rotates, the cam follower moves in the optical axis direction due to the lift of the cam groove, and thereby the second lens frame 19 moves in the optical axis direction.
Reference numeral 33 denotes a first exterior frame attached to the front frame 7. Reference numeral 34 denotes a second exterior frame attached to the first lens frame 8. Reference numeral 35 denotes a manual operation ring (operation member) disposed on the outer periphery of the first exterior frame 33 so as to be rotatable around the optical axis. The manual operation ring 35 is sandwiched between the first exterior frame 33 and the second exterior frame 34 and is prevented from moving in the optical axis direction. Reference numeral 36 denotes an anti-slip rubber ring attached to the outer periphery of the manual operation ring 35. A key 35 a formed on the manual operation ring 35 is engaged with the cam ring 31. For this reason, when the manual operation ring 35 is manually operated and rotated by the user, the cam ring 31 also rotates.
Reference numeral 37 denotes a drive unit that is attached to the front frame 7 and includes a motor, gears, and the like. The output gear 37 a of the drive unit 37 is engaged with a gear portion 35 b formed on the inner periphery of the manual operation ring 35. Thereby, the drive unit 37 can rotationally drive the manual operation ring 35.
FIG. 3 shows an electrical configuration of the video camera of this embodiment. In addition, the same code | symbol as FIG. 1 is attached | subjected to the component (1-5) of the imaging optical system shown in FIG.
Reference numeral 101 denotes an image sensor composed of a CCD sensor, a CMOS sensor, or the like. Reference numeral 102 denotes a second lens actuator that moves the second lens unit 2 (second lens frame 19) in the optical axis direction, and corresponds to a motor in the drive unit 37 shown in FIG.
A fourth lens actuator 103 includes the first and second yokes 14 and 15, the first magnet 16, and the first coil 13 shown in FIG. 1.
A diaphragm actuator 104 drives the diaphragm 5. Reference numeral 105 denotes a second lens encoder configured by the scale 20 and the movement amount sensor 24 shown in FIG. The second lens encoder 105 detects the movement amount of the second lens frame 19 based on the sensor frame reset position described above. Reference numeral 118 denotes a sensor frame reset sensor including photo interrupters 25 and 26.
A fourth lens encoder 106 includes a scale (not shown) and a movement amount sensor (not shown), and detects a movement amount of the fourth lens frame 12 from a predetermined reset position (hereinafter referred to as a fourth lens reset position). .
Reference numeral 119 denotes a fourth lens reset sensor constituted by a photo interrupter or the like, which detects that the fourth lens frame 12 has moved to the fourth lens reset position.
Reference numeral 107 denotes a diaphragm encoder. For example, a system that detects the relationship between the rotational position of the rotor of the diaphragm actuator 104 and the stator by a Hall element provided in the diaphragm actuator 104 is used.
Reference numeral 117 denotes a CPU as a controller (control means) that controls the operation of the video camera. A video signal processing circuit 108 performs processing such as amplification and gamma correction on the output signal from the image sensor 101 to generate a video signal. A contrast component (luminance component) of the video signal is input to the AE gate 109 and the AF gate 110. The AE gate 109 and the AF gate 110 set a signal extraction range for exposure determination and autofocus (AF) from the entire video screen, and output a contrast component within the range.
Reference numeral 114 denotes an AF signal processing circuit that extracts a high frequency component from the contrast component output from the AF gate 110 to generate an AF evaluation value signal. Reference numeral 115 denotes a zoom switch that is operated when the electric zoom is performed. Reference numeral 116 denotes a zoom tracking memory, which indicates the relationship between the subject distance, the position of the second lens unit 2 and the position of the fourth lens unit 4 in order to maintain a focused state during zooming (correct the image plane movement). Zoom tracking information is stored.
A sensor frame actuator 120 includes the third and fourth yokes 27 and 28, the second coil 29, and the second magnet 30 shown in FIGS.
When the zoom switch 115 is operated by the user, the CPU 117 controls the second lens actuator 102 to move the second lens unit 2. At the same time, the CPU 117 calculates the target movement amount of the fourth lens unit 4 based on the zoom tracking information in the zoom tracking memory 116 and the position of the second lens unit 2 detected by the second lens encoder 105. Then, the fourth lens actuator 103 is controlled to move the fourth lens unit 4 by the target movement amount.
Whether or not the movement amount of the fourth lens unit 4 has reached the target movement amount is determined based on the detection result of the fourth lens encoder 106.

In autofocus, the CPU 117 controls the fourth lens actuator 103 to move the fourth lens unit 4 toward a position where the value of the AF evaluation value signal generated by the AF signal processing circuit 114 exhibits a peak. .
Further, in order to obtain an appropriate exposure, the CPU 117 stops the aperture so that the average value of the luminance components that have passed through the AE gate 109 becomes a predetermined value, that is, the output of the aperture encoder 107 becomes a value corresponding to the predetermined value. The actuator 104 is controlled to control the opening diameter.
Next, an outline of the reset operation of the second lens encoder 105 performed when the power of the video camera is turned on will be described with reference to the flowchart of FIG. This reset operation is executed by the CPU 117 according to the computer program.
In step 1, the CPU 117 starts a reset operation of the second lens encoder 105. In step 2, the CPU 117 drives the sensor frame actuator 120 until the sensor frame reset sensor 118 detects that the sensor frame 23 has moved to the sensor frame reset position.
Next, in step 3, the CPU 117 starts detecting the movement amount by the second lens encoder 105 (movement amount sensor 24).
Next, in step 4, the CPU 117 drives the sensor frame actuator 120 so as to move the sensor frame 23 (movement amount sensor 24) from the sensor frame reset position to a predetermined movement amount detection position.
Next, in step 5, the CPU 117 obtains an initial position of the second lens frame 19 (second lens unit 2) according to the output of the second lens encoder 105. In step 6, the reset operation of the second lens encoder 105 is terminated.
The reset operation of the second lens encoder 105 described above will be described in more detail with reference to FIG.
In step 11, the CPU 117 starts a reset operation of the second lens encoder 105.
In step 12, the CPU 117 energizes the second coil 29 of the sensor frame actuator 120 to move the sensor frame 23 to the subject side. Here, when the sensor frame 23 moves to the subject side, the photo interrupters 25 and 26 as the sensor frame reset sensor 118 also move to the subject side together with the sensor frame 23.
Next, in step 13, the CPU 117 determines whether or not the photo interrupter 25 or 26 detects that the sensor frame 23 has been moved to the sensor frame reset position. When the photo interrupters 25 and 26 move to the subject side, the light shielding portion 19a of the second lens frame 19 blocks the detection light of the photo interrupter 25 or 26. As a result, the output of the photo interrupter 25 or 26 changes and the sensor frame 23 has moved to the sensor frame reset position, that is, the sensor frame 23 and the second lens frame 19 (second lens unit 2) It is possible to detect that the positional relationship has been reached.
If it is detected that the sensor frame 23 has moved to the sensor frame reset position, the process proceeds to step 14, and if not detected, the process returns to step 12 to further move the sensor frame 23 to the subject side.
In step 14, the CPU 117 determines whether the photo interrupter 25 or the photo interrupter 26 detects that the sensor frame 23 has been moved to the sensor frame reset position in step 13. Since the position of the sensor frame 23 is different between the case detected by the photo interrupter 25 and the case detected by the photo interrupter 26, it is necessary to divide the subsequent processing. Therefore, the CPU 117 proceeds to step 15 when it is detected by the photo interrupter 25 and proceeds to step 16 when it is detected by the photo interrupter 26.
In step 15, the CPU 117 sets 0 to the photo interrupter flag and proceeds to step 17. In step 16, the CPU 117 sets the photo interrupter flag to 1 and proceeds to step 17.
In step 17, the CPU 117 detects a movement amount of the sensor frame 23 from a state where the sensor frame 23 and the second lens frame 19 (second lens unit 2) are in a predetermined positional relationship. 24 is operated, and movement amount detection by the movement amount sensor 24 is started. Then, the process proceeds to Step 18.
In step 18, the CPU 117 energizes the second coil 29 to hold the sensor frame 23 (movement amount sensor 24) at a predetermined movement amount detection position, and moves the sensor frame 23 to the image plane side (rear side). Let When the sensor frame 23 moves to the image plane side and abuts against the stopper portion 27a of the third yoke 27, the sensor frame 23 cannot move any further. Further, the second magnet 30 attached to the sensor frame 23 is attracted to the stopper portion 27a, so that the sensor frame 23 is fixed. When the sensor frame 23 stops moving, the output of the movement amount sensor 24 also does not change.
In step 19, the CPU 117 determines whether or not the output of the movement amount sensor 24 has changed, and if it does not change, it is assumed that the sensor frame 23 has reached (fixed) the movement amount detection position. Proceed to 20. The CPU 117 stores the movement amount detected by the movement amount sensor 24 from the sensor frame reset position to the movement amount detection position in an internal memory (not shown) provided in the CPU 117 as an initial movement amount detection value.
If the output of the movement amount sensor 24 has changed, it is determined that the sensor frame 23 has not reached the movement amount detection position, and the process returns to step 18 to move the sensor frame 23 further to the image plane side.
In step 20, the CPU 117 determines whether the photo interrupter flag is 0 or not. Here, when the movement of the sensor frame 23 to the sensor frame reset position is detected by the photo interrupter 25 in Step 13 (when the photo interrupter flag is 0), the second is greater than that detected by the photo interrupter 26. The lens frame 19 is located on the subject side.
For this reason, when it is detected by the photo interrupter 25, when the initial position of the second lens frame 19 is obtained, only the difference in position between the photo interrupter 25 and the photo interrupter 26 is detected by the photo interrupter 26. It is assumed that it is located closer to the subject. The CPU 117 stores the position difference between the photo interrupter 25 and the photo interrupter 26 in the internal memory in advance.
If the photo interrupter flag is 0, the process proceeds to step 21, and if it is not 0 (1), the process proceeds to step 22.
In step 21, the CPU 117 obtains the initial position of the second lens frame 19 (second lens unit 2) as the sum of the aforementioned initial movement amount detection value and the position difference between the photo interrupters 25 and 26. Then, the process proceeds to Step 23. On the other hand, in step 22, the CPU 117 sets the initial position of the second lens frame 19 (second lens unit 2) as the initial movement amount detection value. Then, the process proceeds to Step 23.
In step 23, the CPU 117 ends the reset operation of the second lens encoder 105 (the initial position detection operation of the second lens unit 2).

As described above, in this embodiment, the sensor frame 23 holding the movement amount sensor 24 is moved by the sensor frame actuator 120, and the sensor frame 23 is moved to the sensor frame reset position by the photo interrupters 25 and 26 on the sensor frame 23. Detect that it has moved. As a result, even if the manual operation ring 35 for moving the second lens frame 19 is not operated or the manual operation ring 35 is stopped by the user's hand, the sensor frame 23 is set to the sensor frame reset position. Can be moved.
By moving the sensor frame 23 to the sensor frame reset position in this way, a highly accurate position detection of the second lens frame 19 using the amount of movement of the second lens frame 19 detected by the second lens encoder 105 thereafter. Is possible. When the position of the second lens frame 19 (second lens unit 2) is detected with high accuracy, the position of the fourth lens frame 12 (fourth lens unit 4) is controlled based on the detected position during zooming. It is possible to reduce the focus shift.
In this embodiment, the case where the sensor frame 23 is moved to the sensor frame reset position is detected using the two photo interrupters (reset detection means) 25 and 26. However, at least one reset detection means is used. Good. However, by using two reset detection means, the amount of movement of the sensor frame 23 to the sensor frame reset position can be reduced, and the lens barrel portion can be downsized.
Moreover, you may use detection means other than a photo interrupter as a reset detection means. For example, it detects that the sensor frame has moved to the sensor frame reset position by detecting the position at which the gray code pattern switches using a substrate on which the gray code pattern is formed and a brush that slides against the substrate. May be.
Moreover, although the present Example demonstrated the case where the sensor frame 23 (movement amount sensor 24) was fixed to a movement amount detection position with the attraction | suction force of a magnet, you may use methods other than this. For example, a mechanical method in which the sensor frame 23 is pressed against a predetermined stopper portion by a spring force and fixed, or a method in which the sensor frame 23 is electrically fixed may be used.
Further, in the present embodiment, the case where the movement amount sensor 24 is moved together with the sensor frame 23 in the reset operation of the second lens encoder 105 has been described, but the scale 20 may be moved.
Further, the position detection method described in the present embodiment may be used for position detection of optical elements other than the second lens unit 2 (for example, the fourth lens unit 4 or a movable diaphragm).

FIG. 6 shows a side sectional view of a lens barrel of a video camera as an optical apparatus that is Embodiment 2 of the present invention. FIG. 7 shows a cross section (front cross section) of the lens barrel when viewed in the optical axis direction.
Reference numeral 201 denotes a fixed first lens unit. Reference numeral 202 denotes a second lens unit (magnifying lens unit: first optical element) that moves in the optical axis direction for zooming. Reference numeral 203 denotes a fixed third lens unit. Reference numeral 204 denotes a fourth lens unit (focus lens unit: second optical element) that moves in the direction of the optical axis in order to correct image plane fluctuations associated with zooming and focus adjustment. Reference numeral 205 denotes a fixed diaphragm. The first lens unit 101 to the fourth lens unit 104 and the diaphragm 105 constitute an imaging optical system.
Reference numeral 206 denotes a rear frame attached to a camera body (not shown). Reference numeral 207 denotes a front frame attached to the rear frame 206. Reference numeral 208 denotes a first lens frame that holds the first lens unit 201 and is fixed to the front frame 207. Reference numeral 209 denotes a third lens frame that holds the third lens unit 203 and is fixed to the rear frame 206.
Reference numerals 210 and 211 denote guide bars that extend in the optical axis direction and whose both ends are held by the rear frame 206 and the third lens frame 209. A fourth lens frame 212 holds the fourth lens unit 204 and is engaged with the guide bars 210 and 211 so as to be movable in the optical axis direction. The fourth lens frame 212 is guided in the optical axis direction by the guide bar 210, and is prevented from rotating around the guide bar 210 by the guide bar 211.
Reference numeral 213 denotes a first coil fixed to the fourth lens frame 212. Reference numeral 214 denotes a first yoke fixed to the rear frame 206. Reference numeral 215 denotes a second yoke fixed to the front end of the first yoke 214. Reference numeral 216 denotes a first magnet fixed to the first yoke 14. The first coil 213, the first and second yokes 214 and 215, and the first magnet 216 constitute a fourth lens actuator as a linear electromagnetic actuator. The fourth lens actuator generates a thrust in the optical axis direction by energizing the first coil 213, and moves the fourth lens frame 212 in the optical axis direction.
Reference numeral 217 denotes a cam ring as a driving member (movable member) disposed on the outer periphery of the front frame 207 so as to be rotatable around the optical axis. The cam ring 217 is sandwiched between the front frame 207 and the first lens frame 208 and is prevented from moving in the optical axis direction.
Reference numeral 219 denotes a second lens frame that holds the second lens unit 202. Reference numeral 218 denotes a cam follower attached to the second lens frame 219. The cam follower 218 is engaged with a rectilinear groove 207 a formed in the front frame 207 so as to extend in the optical axis direction and a cam groove 217 a formed in the cam ring 217. When the cam ring 217 rotates, the cam follower 218 is moved in the optical axis direction by the lift of the cam groove portion 217a while being prevented from rotating around the optical axis by the rectilinear groove portion 207a. As a result, the second lens frame 219 moves in the optical axis direction. Since the second lens frame 219 (second lens unit 202) moves in conjunction with the rotation of the cam ring 217, it can be said to be a movable member together with the cam ring 217.
A scale 220 is fixed to the outer periphery of the cam ring 217. The scale 220 rotates around the optical axis together with the cam ring 217.
Reference numeral 221 denotes a first exterior frame attached to the front frame 207. Reference numeral 222 denotes a second exterior frame attached to the first lens frame 208. Reference numeral 223 denotes a manual operation ring (operation member: movable member) disposed on the outer periphery of the first exterior frame 221 so as to be rotatable around the optical axis. The manual operation ring 223 is sandwiched between the first exterior frame 221 and the second exterior frame 222 and is prevented from moving in the optical axis direction. An anti-slip rubber ring 224 is attached to the outer periphery of the manual operation ring 223. A key 223 a formed on the manual operation ring 223 is engaged with the cam ring 217. For this reason, when the manual operation ring 223 is manually operated and rotated by the user, the cam ring 217 also rotates.
Reference numeral 225 denotes a drive unit that is attached to the front frame 207 and includes a motor, gears, and the like. The output gear 225a of the drive unit 225 is engaged with a gear portion 223b formed on the inner periphery of the manual operation ring 223. Accordingly, the drive unit 225 can rotationally drive the manual operation ring 223.
Reference numeral 226 denotes a sensor frame holding ring attached to the front frame 207. A sensor frame 227 is held by a sensor frame holding ring 226 so as to be rotatable about the optical axis. Reference numeral 228 denotes a rotation amount sensor (movement amount sensor) that is disposed at a position facing the scale 220 and is held by the sensor frame 227. The rotation amount sensor 228 and the scale 220 rotate relative to each other to constitute a second lens encoder as movement amount detection means (relative position detection means) for detecting the relative rotation amount (relative movement amount or relative position). The rotation amount sensor 228 and the scale 220 are configured in the same manner as the movement amount sensor 24 and the scale 20 described in the first embodiment. The rotation amount sensor 228 rotates around the optical axis together with the sensor frame 227.
Reference numeral 229 denotes a photo interrupter as reset detecting means fixed to the sensor frame 227. The photo interrupter 229 has a light emitting part and a light receiving part. The output of the photo interrupter 229 changes when the light shielding part 217b formed on the cam ring 217 enters between the light emitting part and the light receiving part and blocks detection light from the light emitting part toward the light receiving part. Thereby, it can be detected that the sensor frame 227 has rotated to a predetermined reset position with respect to the cam ring 217 (that is, the second lens frame 219 driven by the cam ring 217). Hereinafter, the reset position of the sensor frame 227 is referred to as a sensor frame reset position.
A photo interrupter 230 is fixed to the front frame 207 and detects that the sensor frame 227 has moved to a predetermined rotation amount detection position (movement amount detection position) with respect to the front frame 207. The photo interrupter 230 has a light emitting part and a light receiving part. In the photo interrupter 230, the light shielding part 227a formed in the sensor frame 227 enters between the light emitting part and the light receiving part and blocks the detection light traveling from the light emitting part to the light receiving part, whereby the sensor frame 227 is positioned at the rotation amount detection position. Detects rotation.
Reference numeral 231 denotes a sensor frame actuator that rotates and moves the sensor frame 227. By rotating the sensor frame 227 by the sensor frame actuator 231, the relative position between the rotation amount sensor 228 and the scale 220 can be changed. Further, the sensor frame 227 is held at the rotation amount detection position by stopping the sensor frame actuator 231 in response to detecting that the sensor frame 227 is rotated (moved) to the rotation amount detection position by the photo interrupter 230. Can do.
FIG. 8 shows an electrical configuration of the video camera of this embodiment. The components (201 to 205) of the imaging optical system and the sensor frame actuator 231 shown in FIGS. 6 and 7 are denoted by the same reference numerals as those in FIGS.
Reference numeral 301 denotes an image sensor composed of a CCD sensor, a CMOS sensor, or the like. Reference numeral 302 denotes a second lens actuator that moves the second lens unit 2 (second lens frame 19) in the optical axis direction, and corresponds to a motor in the drive unit 225 shown in FIG.
A fourth lens actuator 303 includes the first and second yokes 214 and 215, the first magnet 216, and the first coil 213 shown in FIG.
A diaphragm actuator 304 drives the diaphragm 205. Reference numeral 305 denotes a second lens encoder including the scale 220 and the rotation amount sensor 228 shown in FIGS. The second lens encoder 305 detects the amount of movement of the second lens frame 219 (the amount of rotation of the cam ring 217) based on the sensor frame reset position described above. Reference numeral 318 denotes a sensor frame reset sensor including a photo interrupter 229.
Reference numeral 306 denotes a fourth lens encoder that includes a scale (not shown) and a movement amount sensor (not shown), and detects the movement amount of the fourth lens frame 212 from a predetermined reset position (hereinafter referred to as a fourth lens reset position). .
Reference numeral 319 denotes a fourth lens reset sensor constituted by a photo interrupter or the like, which detects that the fourth lens frame 212 has moved to the fourth lens reset position.
Reference numeral 307 denotes an aperture encoder. For example, an aperture encoder that detects the relationship between the rotational position of the rotor of the aperture actuator 304 and the stator by a Hall element provided inside the aperture actuator 304 is used.
Reference numeral 317 denotes a CPU as a controller (control means) that controls the operation of the video camera. Reference numeral 308 denotes a video signal processing circuit, and reference numerals 309 and 310 denote an AE gate and an AF gate, respectively. Reference numeral 314 denotes an AF signal processing circuit. The roles of the video signal processing circuit 308, the AE gate 309, the AF gate 310, and the AF signal processing circuit 314 are the same as those in the first embodiment.
Reference numeral 315 denotes a zoom switch that is operated when the electric zoom is performed. Reference numeral 316 denotes a zoom tracking memory. The role of the zoom tracking memory 316 is also the same as in the first embodiment.
Reference numeral 321 denotes an encoder rotation amount detection position sensor that includes the photo interrupter 230 and detects that the sensor frame 227 has rotated (moved) to the rotation amount detection position.

In the above configuration, the operation when the zoom switch 315 is operated by the user, the operation in autofocus, and the operation for obtaining proper exposure are the same as those in the first embodiment.
Next, an outline of the reset operation of the second lens encoder 305 performed when the video camera is turned on will be described with reference to the flowchart of FIG. This reset operation is executed by the CPU 317 in accordance with the computer program.
In step 101, the CPU 317 starts a reset operation of the second lens encoder 305. In step 102, the CPU 317 drives the sensor frame actuator 231 until the sensor frame reset sensor 318 detects that the sensor frame 227 has rotated to the sensor frame reset position.
Next, in step 103, the CPU 317 starts detecting the rotation amount by the second lens encoder 305 (rotation amount sensor 228).
Next, in step 104, the CPU 317 drives the sensor frame actuator 231 to move the sensor frame 227 (rotation amount sensor 228) from the sensor frame reset position to the rotation amount detection position.
Next, in step 105, the CPU 317 obtains the initial position of the second lens frame 219 (second lens unit 202) according to the output of the second lens encoder 305. In step 106, the reset operation of the second lens encoder 305 is terminated.
The above-described reset operation of the second lens encoder 105 will be described in more detail with reference to FIG.
In step 111, the CPU 317 starts the reset operation of the second lens encoder 305.
In step 112, the CPU 317 energizes the sensor frame actuator 231 to rotate the sensor frame 227 in the clockwise direction in FIG. Here, when the sensor frame 227 rotates, the photo interrupter 229 that is the sensor frame reset sensor 318 also rotates together with the sensor frame 227.
Next, in step 113, the CPU 317 determines whether or not the photo interrupter 229 has detected that the sensor frame 227 has been rotated to the sensor frame reset position. When the photo interrupter 229 rotates in the clockwise direction in FIG. 7, the light shielding portion 217b of the cam ring 217 blocks the detection light of the photo interrupter 229, and the output of the photo interrupter 229 changes. As a result, the sensor frame 227 is rotated to the sensor frame reset position, that is, the sensor frame 227 and the cam ring 217 (that is, the second lens unit 202 held by the second lens frame 219) have a predetermined positional relationship. Can be detected.
If it is detected that the output of the photo interrupter 229 has changed and the sensor frame 227 has rotated to the sensor frame reset position, the process proceeds to step 114. If not detected, the process returns to step 112, and the sensor frame 227 is further moved to the position shown in FIG. Rotate clockwise.
In step 114, the CPU 317 operates the rotation amount sensor 228 to detect the rotation amount of the sensor frame 227 from the state where the sensor frame 227 and the cam ring 217 are in a predetermined positional relationship, and the rotation amount sensor 228. The rotation amount detection by is started. Then, the process proceeds to step 115.
In step 115, the CPU 317 energizes the sensor frame actuator 231 to rotate the sensor frame 227 in the counterclockwise direction in FIG. 7 in order to rotate the sensor frame 227 to the rotation amount detection position. When the sensor frame 227 rotates counterclockwise in FIG. 7, the light shielding portion 227a of the sensor frame 227 blocks the detection light of the photo interrupter 230 (encoder rotation amount detection position sensor 321), and the output changes. Thereby, it can be detected that the sensor frame 227 has moved to the rotation amount detection position.
Next, in step 116, the CPU 317 determines whether or not the output of the photo interrupter 230 has changed. If changed, it is assumed that the sensor frame 227 has rotated to the rotation amount detection position, and the process proceeds to step 117. The CPU 117 stores the rotation amount detected by the rotation amount sensor 228 from the sensor frame reset position to the rotation amount detection position in an internal memory (not shown) provided in the CPU 317 as an initial rotation amount detection value.
If the output of the photo interrupter 230 does not change, it is determined that the sensor frame 227 has not rotated to the rotation amount detection position, and the process returns to step 115, and the sensor frame 227 is further rotated counterclockwise in FIG.
In step 117, the CPU 317 stops the sensor frame actuator 231 and holds the sensor frame 227 at the rotation amount detection position. Then, the process proceeds to Step 118.
In step 118, the CPU 317 sets the initial position of the second lens unit 202 (the initial rotation position of the cam ring 217) as the initial rotation amount detection value. In step 119, the reset operation of the second lens encoder 305 (the initial rotation position detection operation of the second lens unit 202) is terminated.
As described above, in this embodiment, the sensor frame 227 holding the rotation amount sensor 228 is rotated by the sensor frame actuator 231, and the sensor frame 227 is rotated to the sensor frame reset position by the photo interrupter 229 on the sensor frame 227. Detect that. As a result, even if the manual operation ring 223 for moving the second lens frame 219 is not operated or the manual operation ring 223 is stopped by the user's hand, the sensor frame 227 is set to the sensor frame reset position. Can be rotated.
By moving the sensor frame 227 to the sensor frame reset position in this way, a highly accurate position detection of the second lens frame 219 using the amount of movement of the second lens frame 219 detected by the second lens encoder 305 thereafter. Is possible. When the position of the second lens frame 219 (second lens unit 202) is detected with high accuracy, the position of the fourth lens frame 212 (fourth lens unit 204) is controlled based on the detected position during zooming. It is possible to reduce the focus shift.
Moreover, you may use detection means other than a photo interrupter as a reset detection means. For example, it detects that the sensor frame has moved to the sensor frame reset position by detecting the position at which the gray code pattern switches using a substrate on which the gray code pattern is formed and a brush that slides against the substrate. May be.
In the present embodiment, the case where the second lens encoder 305 detects the rotation amount of the cam ring 217 has been described. However, the rotation amount of the manual operation ring 223 that rotates integrally with the cam ring 217 may be detected.
Furthermore, in the present embodiment, the case where the rotation amount sensor 228 is rotated together with the sensor frame 227 in the reset operation of the second lens encoder 305 has been described, but the scale 220 may be rotated.
Further, the position detection method described in the present embodiment may be used for position detection of an optical element other than the second lens unit 202 (for example, the fourth lens unit 204 or a movable diaphragm).
Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.
For example, although the video camera has been described in each of the above embodiments, the present invention can be applied to various optical devices such as a digital still camera and an interchangeable lens.

An optical apparatus that can detect the position of the movable member with high accuracy without using the absolute position detector can be realized.

1,201 First lens unit 2,202 Second lens unit 3,203 Third lens unit 4,204 Fourth lens unit 5,205 Aperture 12,212 Fourth lens frame 19,219 Second lens frame 20,220 Scale 23, 227 Sensor frame 24 Movement amount sensor 25, 26, 229 Photo interrupter 31, 217 Cam ring 35, 223 Manual operation ring 120, 231 Sensor frame actuator 226 Sensor frame holding ring 228 Rotation amount sensor 230 Photo interrupter

Claims (3)

A movable first optical element;
An operating member operated to move the first optical element;
The first optical element, the operation member, and a drive member that drives the first optical element in accordance with an operation of the operation member. A movement amount detecting means for detecting a movement amount of the movable member;
A holding member for holding the scale or the movement amount sensor;
An actuator for moving the holding member;
Reset detecting means for detecting that the holding member has been moved to a predetermined reset position with respect to the movable member by the actuator;
An optical apparatus that detects a position of the movable member using a movement amount from the reset position detected by the movement amount detection means.   The optical apparatus according to claim 1, further comprising a control unit that moves the second optical element according to the position of the movable member.   The optical apparatus according to claim 1, wherein two reset detection units are provided in a moving direction of the holding member.