JPH0414005A - Lens driving device - Google Patents

Abstract

PURPOSE:To obtain a high-performance zoom lens which can have the best floating configuration by driving the zoom lens by a motor,reading the best extension quantity out of a memory, and driving and controlling the respective lenses. CONSTITUTION:The zoom lens consists of 1st-4th group lenses, which are provided so that they are not put in uniform motion set through a cam cylinder, but driven by four linear ultrasonic motors 521-524. When zooming operation is started by a zoomming operation input part 60, a CPU 57 reads the best focusing extenmsion quantity out of a ROM 56 according to a wide-angle or telephoto zooming state to drive the respective lenses by the motors 521-524 respectively. Therefore, the high-performance zoom lens is obtained because of a focusing mechanism which takes the best focusing configuration according to the zooming state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens driving device for driving a lens in a camera equipped with a photographing lens that can move the lens in the optical axis direction for the purpose of zooming or focusing.

[Prior Art] Conventionally, as a method of focusing a photographic lens for a camera, methods such as extending the entire lens group or extending a lens group partially have been used. Among these, methods of partially extending lens groups, such as inner focus, which require a small amount of lens group movement, have been attracting attention in recent years.

In addition, methods for extending some lens groups are becoming more and more sophisticated, and in order to suppress the occurrence of aberrations due to focusing, the so-called floating type, in which two or more lens groups move differently during focusing, is increasing. .

Then, in order to give these lens groups a predetermined operation,
A photographic device with zooming and focusing functions that is configured so that a cam cylinder with a cam groove guides a pin provided in the lens frame and the positional relationship of the lenses is set in a predetermined state. Lenses have been widely used in cameras.

[Problems to be Solved by the Invention] With the conventional method using a cam cylinder as described above, it is extremely difficult due to its structure to perform a plurality of floating modes having different positional relationships during movement. On the other hand, in zoom lenses whose number has been increasing in recent years, the floating form most suitable for suppressing focusing aberrations often differs depending on the zoom state, for example, the wide state and the tele state.

For this reason, when using a floating focusing mechanism in a zoom lens, it is necessary to use a floating mode of movement that is most suitable for wide-angle conditions at close distances, and a floating movement mode that is most suitable for telephoto conditions at long distances. This was the only floating configuration that minimized aberrations. However, with this method, aberrations may not be suppressed depending on the zoom state or the distance of the subject, which has been a problem when creating a high-performance zoom lens.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a lens driving device that can obtain a high-performance zoom lens using a focusing mechanism that takes an optimal floating configuration depending on the zoom state, and that can also reliably suppress aberrations caused by focusing. purpose.

[Means for Solving the Problems] A lens driving device of the present invention includes a plurality of lens groups including a plurality of focusing lens groups movable in the optical axis direction, and drives each of the plurality of lens groups with different drive amounts. a focal length information outputting means for outputting focal length information corresponding to the focal length of the lens group, a zoom extension amount of the focusing lens group determined based on the focal length information, and the plurality of focusing lenses. The focusing extension amount of each group is set so that the floating amount differs depending on the focal length even at the same focusing position, and the focusing extension amount is determined for each focusing lens group based on the focal length information and the focusing position information. means, a target position output means for outputting a drive target position of the focusing lens group based on the zoom extension amount and the focusing extension amount, and a drive target position of each of the focusing lenses output from the target position output unit and drive control means for driving each group.

[Function] In the lens driving device of the present invention, the floating amount at the time of focusing is not simply set by conventional means such as a cam barrel, but the optimal focusing amount and amount are set based on the zoom state. Or, by reading necessary numerical values such as the coefficients of the calculation formula for calculating the focusing extension amount from the memory and driving and controlling each lens group based on the output focusing extension amount,
A high-performance zoom lens can be obtained by using a focusing mechanism that can take an optimal floating configuration depending on the zoom state, and moreover, it is possible to reliably suppress aberrations caused by focusing.

[Examples] Examples of the present invention will be described below with reference to the drawings.

First, as a first example, a case where the present invention is applied to a zoom lens having a four-group configuration will be described.

FIG. 7 is a diagram showing the movement of each lens group according to the present invention. In other words, as shown in the figure, when the focal length is changed from wide to telephoto by zooming, the first group lens and second group lens
The lens group, the third lens group, and the fourth lens group are moved toward the focal plane by different amounts of movement (the solid line in the figure indicates the position of the final surface of each lens when focusing is performed). Furthermore, during wide, standard, and telephoto focusing, the second and third group lenses are
As shown by the broken line in the figure, the focus is extended from infinity to close range, and the amount of focusing extension differs depending on each focal length. It is difficult to create a zoom lens with such lens movement using a frame structure using a conventionally known cam or the like.

Therefore, in the present invention, for example, a frame structure as shown in FIG. 2 is used. That is, the first group lens 71, the second group lens 72, the third group lens 73, and the fourth group lens 7
4 are respectively 1 front frame 75. 2 front frame 76. 3 front frame 77,
and 4 is fixedly held on the front frame 78. 2 front frame 76.
The third front frame 77 and the fourth front frame 78 are provided at the inner circumferential portion of the first front frame 75 so that they can be moved only in the optical axis direction inside the hollow frame portion of the first front frame 75 extending toward the camera body 79 side. Bearings 85, 86.
It is pressed in 87 directions. Therefore, the second front frame 76.
The third front frame 77 and the fourth front frame 78 each have bearings 85,
86, 87 and each of the vibrating bodies 81, 82, 83, the first front frame 75 is positioned without any displacement in the optical axis direction or with respect to the optical axis center, and without any wobbling.

Further, the first front frame 75 is guided by a bearing 84 disposed on the inner circumference of the fixed frame 88 so as to be movable only in the optical axis direction, and is The vibrating body 8 disposed on the fixed frame 88 at the position
0 toward the bearing 84. Therefore, the first front frame 75 is also positioned with respect to the fixed frame 88 without play. Note that 89 is a cover and 90 is a film surface.

Next, the details of the installation of the vibrator and the operation of the linear ultrasonic motor will be described. Although four linear ultrasonic motors are used in this embodiment, the installation and operation are the same, so the linear ultrasonic motor used for the first front frame 75 will be described as a representative.

FIGS. 4 and 5 are diagrams showing details of the linear ultrasonic motor. That is, inside the fixed frame 1 (88), which is a fixed member made of a hollow cylindrical body, there is a fixed frame 2 (75), which is a movable member also made of a hollow cylindrical body, with a fixed gap in the center. It is arranged so that it can move in the direction of the axis O. A slide plate 3 extending in the direction of the central axis O of the first resolution frame 2 is fixed onto the first resolution frame 2 in a part of the upper part of the gap between the fixed frame 1 and the first resolution frame 2 (in FIG. 4). and
In the middle part of the fixed frame 1 facing the slide plate 3, there is a rectangular notch hole 1 which is long in the front and back direction of the central axis O direction.
d (see Figure 5) is drilled. This notch hole 1d is a hole for arranging a vibrating body 12 (80), which will be described later.

On the other hand, in a gap opposite to the gap in which the slide plate 3 is disposed, a support and guide mechanism for the single frame 2 is provided. In this embodiment, this support and guide mechanism is composed of three guide grooves and a support body made up of a plurality of bearing balls disposed in each of the grooves. That is, at opposing positions across the central axis O of the slide plate 3, a straight groove 2b consisting of a partially arcuate recess is bored in the outer circumferential surface of the one-solution frame 2 in the direction of the central axis O of the one-solution frame 2, Straight groove 2 on the inner peripheral surface of fixed frame 1
In the middle of the position facing b, a straight groove 1b consisting of four partially arcuate parts is provided in the direction of the central axis 0 of the fixed frame 1. At equidistant positions, straight lines Jla, 2alc, and 2c, which are also made of partially arcuate recesses, are bored in the outer circumferential surface of the fixed frame 1 and the inner circumferential surface of the fixed frame 2, respectively, toward the central axis O direction. ing. Support bodies 13a, 13b and 13c each consisting of a plurality of bearing balls are arranged in the straight grooves 1a, 2a, lb, 2b, lc and 2c, respectively.

In this support guide mechanism, the support body 13b of the first frame 2 is
When a vibrating body 12 (described later) disposed at a position facing
~13c acts as a centripetal action, and 1 solution frame 2 becomes fixed frame 1
It is placed accurately and precisely so that the central axis coincides with the

Moreover, since the supports 138 to 13c have a plurality of bearing balls arranged in the direction of the central axis 0 of the fixed frame 1,
1. The front frame 2 is supported without any deviation of the center axis. moreover,
Since the front frame 2 is supported only by the supports 13a to 13C, only the straight grooves 1a to 1c and 2a to 2C of the front frame 2 and the fixed frame 1 should be machined with high precision. For example, the first front frame 2 can be accurately positioned with respect to the fixed frame 1.

As shown in FIG. 4, the notch hole 1d is bored at the middle of the upper part of the fixed frame 1, facing the slide plate 3. That is, a flat part is formed by cutting the middle of the upper peripheral surface of the fixed frame 1 in a direction perpendicular to the central axis O, and a notch hole 1d consisting of an axially long rectangular through hole is formed in the center of the flat part. It is perforated.

Therefore, on both sides of the notch hole 1d in the axial direction, there are flat portions 1d.
o is formed, and this plane portion 1do serves as a mounting portion for the holder 8 that supports the vibrating body 12.

The vibrating body 12 is composed of a bending vibrator 11 and a vertical vibrator 4. The bending vibrator 11 includes a relatively thick rectangular elastic body 5 that is arranged with a margin in the notch hole ld, and a rectangular piezoelectric body 6 that is shorter in length and thinner than the elastic body 5. The piezoelectric body 6 is fixed to the upper surface of the elastic body 5 using an epoxy adhesive. and,
A driving high-frequency voltage is applied to the piezoelectric body 5 of the bending vibrator 11 in the thickness direction thereof, and in the case of this embodiment, a first-order bending resonance is generated. ing. At the two nodes of this bending vibration, a vertical vibrator 4 that vibrates longitudinally in the thickness direction of a laminated plate formed in a rectangular column shape of a laminated piezoelectric body is bent on the lower surface of the elastic body 5 to which the piezoelectric body 6 is not fixed. It is fixed so as to vibrate longitudinally in the thickness direction of the vibrator 11.

Further, the bending vibrator 11 has four cylindrical support pins 7 fixed to the elastic body 5 that extend outward in the board width direction of the bending vibrator 11 at the node positions thereof. A holder attachment groove 7a is provided in the middle of the bottle 7 in the circumferential direction.

The vibrating body 12 configured in this way has a channel-shaped cross section and is housed and held from below in a holder 8 formed in a shape to cover the vibrating body 12 from above. That is,
The holder 8 is formed by bending an elastic thin plate, and has an oval hole-shaped receiving portion 8a with an open bottom at a position corresponding to the support pin 7 on the hanging wall of the holder 8. The lower open portion 8a is formed with a notch having a width slightly smaller in diameter than the diameter of the holder attachment groove 7a. Further, in the middle of the rain hanging wall of this holder 8, mounting fixing parts 8b are provided which are bent outward and extend horizontally, and fixing screws 10 are attached to the mounting fixing parts 8b. Apertures 8C are formed therethrough.

The vibrating body 12 is housed in the holder 8 so as to be able to vibrate freely by loosely fitting the holder mounting groove 7a of the support pin 7 into the receiving part 8a, and then opening the holder 8. The vibrating body 12 is attached to the fixed frame by passing the fixing screw 10 through the fixing screw 10 through the disc spring 9 and screwing the fixing screw 10 into the screw hole 1e screwed into the flat part 1do of the fixed frame 1. It is arranged in the notch hole 1d of 1. This arranged vibrating body 12 is pressed against the lower end surface of the vertical vibrator 4 or the upper surface of the slide plate 3 fixed to the front frame 2.

The operating principle of the ultrasonic motor configured as described above is the same as that of Japanese Patent Application No. 1195767 previously proposed by the present applicant. Elliptical vibration that moves the frame 2 back and forth in the direction of its central axis O is generated on the end face of the longitudinal vibrator 4. The two longitudinal vibrators 4 are configured to vibrate with a phase difference of 180°, so that only one direction of the pendulum vibration around the nodes caused by the bending vibration is applied to the slide plate 3 of the front frame 2. Let it work. Therefore, this causes the first front frame 2 to move forward and backward in the direction of the central axis 0.

Next, the configuration of the electric circuit of the first embodiment will be explained with reference to FIG. In the figure, 521 to 524 are the second
Linear type ultrasonic motors corresponding to the vibrating bodies 80, 81, 82°83 in the figure, 511 to 514 are ultrasonic motors 52□ to
This is an encoder that is driven by 524 and detects the movement of the frame. The encoders 511 to 514 consist of a scale in which the scales are written in two rows at equal intervals and with the phase shifted, and a reading section for the scale, and another row of scales is also written on the scale to indicate the end position that is the reference value. It's included.

In this case, for the encoder 511, the scale is arranged in the fixed frame 1, and the reading part is arranged in the 1st front frame 75, and for the encoders 51□ to 514, the scale is arranged in the 2nd front frame 76 and the 3rd front frame, respectively. 77.4 In the front frame 78,
Further, reading sections are arranged in the first front frame 75, respectively. When the reading section moves relative to the scale, a pulse is generated and output at the position where the scale passes.

531 to 534 are direction detection circuits, and the encoder 51
The direction of movement is detected from the phase inversion of two series of pulses with different phases generated by numerals 1 to 514.

551 to 554 are up/down counters that detect absolute positions from the pulses output by the encoders 511 to 514 and the moving direction signals output by the direction detection circuits 53 and 534, and indicate the reference positions output by the encoders 511 to 514. It is reset by a pulse, and counts up the pulse corresponding to the equally spaced scale when in the feeding direction, and counts down when in the feeding direction.

Reference numeral 54 denotes an ultrasonic motor 52. A drive circuit 59 drives pulses generated by the drive circuit 54 to ultrasonic motors 521 to 524.
Either one is a switching circuit that switches to one side.

The drive circuit 54 and switching circuit 59 are shown in FIG. Note that the drive circuit 54 is the same as, for example, the third embodiment of Japanese Patent Application No. 1337024, so the details will be omitted. Further, the switching circuit 59 may be configured to include, for example, a photo MOS relay PMI IPM12. as shown in FIG. PM13. PM14. P
M21°PM22. PM2B and PM24, whose opening and closing are controlled by control signals from the calculation control section 57.

56 is a ROM that supplies programs and various memory data necessary for arithmetic control, which will be described later; 58 is a ROM that supplies, for example,
- An AF (autofocus) module using a known triangulation method as shown in Publication No. 124515, etc.
60. is the zoom operation input section using buttons for zooming. 57 is an arithmetic control section, and a counter 55
Each output from 1 to 554 (position information) AF module 5
8 (distance measurement information) The output of the zoom operation input unit 601 is taken in as appropriate, and a drive control signal for driving the ultrasonic motors 52° to 524 is output to the drive circuit 54.

FIG. 3 is an overview diagram of the camera in the first embodiment,
A camera body 91, a release button 92 that can output signals (first release when pressed halfway) and second release when pressed fully, a window 93 for the finder that determines the angle of view, and a measuring button that guides light to a distance sensor (not shown). Distance window 94, photographic lens 95, zoom operation input section (zoom button) 6o1
It's empty.

Next, based on the flowchart shown in FIG.
A zooming operation according to an embodiment will be explained. Zoom operation input section 60. When you operate , zooming operation starts. First, the photomos relay PMII shown in Fig. 6
, PM21 is turned on (F41), and a drive pulse is generated by the drive circuit 54, the linear ultrasonic motor 52 is immediately activated.
1 can start driving the first group lens 71.

Next, for zoom operation, check whether the tele button is pressed or the wide button is pressed.
), if the zoom operation continues, the drive continues; if the zoom operation has stopped, the first group lens 71 is stopped (F44F47). If the wide button has been pressed, a similar operation is performed on the retracting side to stop the first group lens 71 (F45.F46.F47). In other words, only the first lens group 71 moves during zooming.

Next (after the zooming operation is completed), the photo MOS relays PMII and PM21 are turned off (F48), and then the position of the first group lens 71 is read from the counter 551 (F49). Then, based on the values, the reference positions of the second lens group 72, the third lens group 73, and the fourth lens group 74 are output (F50). Here, the reference position is the positional relationship in the infinity focus state in each zoom state as shown in FIG. Once the position of the first group lens 71 is determined, the respective reference positions of the second group lens 72, the third group lens 73, and the fourth group lens 74 are determined. In this embodiment, the position of the first group lens 71 is divided into small parts, and the first
Each reference position for the group lens 71 is written in the ROM 56, and the positions of the second to fourth group lenses 72 to 74 are output by referring to the values.

Next, Photomos relay PM12. Turn on PM22 (F51), drive the second group lens 72 (F52), and when the position of the second group lens 72 calculated above is reached (F5
B) Stop driving the second group lens 72 (F54).

Similarly, the third group lens 73 and the fourth group lens 74 are moved while switching the photomos relay (F55 to F55).
61).

As described above, after the second to fourth group lenses 72 to 74 are driven to the reference position, the series of zooming ends. In other words, when the zooming operation is completed, the lens stands by at the infinity focus position in the focal length state.

Next, based on the flowchart shown in FIG.
A focusing operation according to an embodiment will be explained. When the release button 92 is pressed halfway, focusing operation begins. Here, in order to know the zooming state, the position of the first group lens 71 is read from the counter 55□ (F
l). Next, the AF module 58 performs a distance measuring operation (F2), and if a detectable output is obtained (F3), the amount of movement of the second group lens 72 is output (F4).

The amount of extension of the third group lens 73 is also output (F5).

Here, the method of outputting the positions of the second group lens 72 and the third group lens 73 is by using a memory, as in the case of the zooming operation described above. That is, the first group lens 7
From position 1, determine whether the zoom state is close to wide, standard, or tele, and then
), refer to the amount of movement of the second group lens 72 and third group lens 73 from the basic position stored for each minute distance measurement value by referring to the pig written in the ROM 56. Output by In addition, Fig. 10(a) shows the lens group movement amount with respect to the subject distance at wide-angle mode.
FIG. 10(b) shows the amount of movement of the lens group with respect to the subject distance in standard mode, and FIG. 10(c) shows the amount of movement of the lens group with respect to the subject distance in telephoto mode.

Next, Photomos relay PM12. Turn on PM22 (F6) and start driving the second group lens 72 (F7),
When the above-described extension amount of the second group lens 72 is reached (F8),
Stop driving the second group lens 72 (F9). Similarly,
The third group lens 73 is driven (FIO-Fl4), and when this operation is completed, the lens is in focus. Here, if the second release is turned on (fully pressed) (F
l5), the exposure operation is performed (Fl6), the second group lens 72 and the third group lens 73 are retracted to the reference position (F17 to F25), and the film is wound (F26).
A series of actions ends.

On the other hand, if you release the release button 92 (Fl5.
F27), second group lens 72 and third group lens 73
is renormalized (F17 to F25) and the series of operations ends.

As described above, according to the first embodiment, the optimum floating form can be obtained in each of the zooming states, that is, the wide, standard, and telephoto states, so that there is little deterioration caused by adjusting the focus of the image, and the closest distance that can be photographed is It has a remarkable effect on improving images and expanding the shooting distance range, such as by being smaller. Moreover, this can be done with just one drive circuit, and the electrical circuit is simple.
In addition, since the lenses are moved one group at a time, it is possible to realize a configuration in which the maximum current consumption can be kept low.

Note that the lens position calculation method described above may be calculated from a small number of coefficients and data using an approximation formula or an interpolation formula depending on the required accuracy.

Next, as a second example, a zoom lens with a variable floating form similar to the first example is attached.
A case in which the present invention is applied to an eye reflex camera will be explained.

FIG. 11 is an overview diagram of a single-lens reflex camera in the second embodiment. In other words, the camera body 101 has two functions: first release when pressed halfway and second release when pressed fully).
A release button 102 that can output a signal, a finder 103 using a pentaprism that determines the angle of view, a quick-return main mirror 104 that guides light to the finder 103, and a main mirror 104 attached to the main mirror 104 that directs light from the center of the body. Even if a sub-mirror 105 or the like that guides the AF module 58 disposed at the bottom is disposed. Furthermore, a zoom operation input section 60 and a focusing operation input section 602 are provided on the side surface of the photographic lens 106.

Note that the lens configuration, frame configuration, etc. are the same as those in the first embodiment, so their explanations will be omitted.

Next, the configuration of the electric circuit system of the second embodiment will be explained with reference to FIG. Since this example assumes a TTL camera, if the lens groups are moved one group at a time, and by a large amount, the lens position relationship that was assumed at the time of design will be greatly deviated, resulting in unexpected deterioration of the image. , it gives a feeling of discomfort to the photographer looking through the finder, and makes it difficult to operate the camera while looking through the finder. Therefore, in this embodiment, each lens group is driven in parallel to prevent the positional relationship of the lenses from being disrupted as much as possible. Therefore, unlike the first embodiment, dedicated drive circuits 54□ to 544 are provided for the first to fourth lens groups 71 to 74, respectively, and the arithmetic control unit 5
7, each is controlled independently. Therefore, the first
There is no switching circuit 59 as in the embodiment. Further, in this embodiment, a focusing operation input section 60□ for manual focusing for adjusting the focus by manual operation is provided. This manual focus is electrically driven, so it is called power focus.

The rest of the configuration is the same as that of the first embodiment, and will therefore be omitted.

FIG. 13 is a flowchart illustrating the zooming operation in the second embodiment. That is, the zoom operation manual section 60. When is operated, a zooming mode is entered, and the current focus state (initial focus state) is first stored in a manner described later (F101). Next, check whether the inserted button is a tele button or a wide button.
102) Start driving each lens group in the direction of the telephoto side if the button is a tele button, or the wide side if the button is a wide button.

That is, for example, when the tele button is pressed, the position of the first group lens 71 is first read out (F 10 B).
From this value, the speed of each lens group is output by referring to the data stored in the ROM 56 (F2O3), and a drive signal is generated for the linear ultrasonic motors 52□ to 524 in accordance with the output (F105). If the zoom operation has stopped (F106), each lens group is stopped (F2O3), and if the zoom operation continues, the process returns to step F103. This also applies when the wide button is pressed (F108 to F112).

Next, an operation is started to accurately return to the initial focus position, and the position of the first group lens 71 is read out again (F11
3). Then, the initial focus state stored in step F101 is read out (F114), and the accuracy of the second to fourth group lenses 72 to 74 taking into account the initial focus state of the second to fourth group lenses 72 to 74 is read out. output the position (F115). After that, the second to fourth group lenses 72 to
To start driving the lens 74 (F116), first drive the second group lens 7.
To determine whether the position No. 2 is the final position outputted above, select F118. F119), and if the final position has been reached, the driving of the second group lens 72 is stopped (F120). Further, if the process has already been stopped, steps F118 to F120 are skipped. Similarly, the third group lens 73 and the fourth group lens 74
(F121 to F128), and when all lens groups stop (F129), the zooming operation ends.

Next, the method of outputting the driving speed of each lens group, the method of outputting the final position, and the storage of the focus state used in the explanation of the zooming operation will be explained.

FIG. 14 shows the basic movement amounts of the second group lens 72, third group lens 73, and fourth group lens 74 relative to the first group lens 71 relative to the amount of extension of the first group lens 71 (in a state where the focus is at infinity). This indicates the amount of movement in the area. In the figure, plus (
+) indicates the lens extension direction, and minus (-) indicates the lens extension direction, indicating the amount of change from the wide-angle state. Fig. 15 shows the result obtained by differentiating this by the amount of extension of the first group lens 71 and multiplying it by a constant. Indicates movement speed. That is, if the lenses are driven with the speed relationship shown in FIG. 15, the positional relationship of the lenses when focusing at infinity will always lie on the curve shown in FIG. 14.

On the other hand, in this embodiment, as shown in FIG. 16, the floating form changes continuously between wide, standard, and tele. However, since the focus shift during zooming is not so noticeable except at close range, in this embodiment, the initial focus state is correctly restored only when the zoom operation is completed. The lens is driven according to the relationship shown in the figure. That is, the drive control parameters corresponding to the determined driving speed of the basic first group lens 71 and the second to fourth group lenses 72 to corresponding to the position of the first group lens 71 are determined.
Drive control parameters corresponding to 74 drive speeds are stored in ROM.
56, and by reading the position of the first lens group 71, the speed of each lens group can be output.

Next, a method of storing the focus state and a method of outputting the final position of each lens group will be explained. By zooming,
Assume that the first lens group 71 moves from X' to position X'. For example, the position X (Pi
) is X (PI) −X (BPj') +X (F
Multiply by Pi').

Here, X (BPI') is the amount of movement from the wide basic position due to zooming, and X (FPi') is the amount of movement from the basic position (infinity state) due to focusing. First, regarding X (BPi), the amount of extension of the first group lens 71 and the basic movement amount (Xl , X (BPil)), -(xn
.

X (BPin) ), . . . are stored. The points are indicated by the symbols B Pil, . . . , BPin, . Linear interpolation is performed between this finite number of data points. As is clear from the figure, if the above points are fine enough,
X (BPI') can be output with considerable accuracy. Writing this as a formula, the first group lens 71 at the end of zooming
The position of x' is the position of the data point between it xn
If X nil, it can be written as.

On the other hand, regarding X (FPI'), for each finite in-focus subject distance, a finite number of data point groups (L H,...
・Ljh, ...), and the data points included in the data point group Lih are FPihl, ..., FPihj.

It is indicated by the symbol... Here, h is an integer that increases monotonically from infinity toward the closest distance. X(FPj
) is calculated as follows. First, the amount of movement of the i-th group lens from the reference position due to focusing before starting zooming is between Lih and Lih+1 FP3'
shall be. At this time, the four data points surrounding this FP3' are F P 1hjF P ihj+1 , F P
ih+1j, F P ih+1j+1, then the straight line F P ihj of FP3, F P ih
j+1 and straight line F P ih+1j , F P 1h
The ratio of the distance in the vertical axis direction to +1j+1 is calculated. If this ratio is all -a, the focus state is rh+
I remember that it is a.

In other words, when Lih and Lih villages are close, it is assumed that the focal points at the same distance between them maintain a linear relationship with respect to the vertical axis direction. With this idea, the final point FPI'
The focus extension amount X (FPi') of the first group lens 7 is
If the stop position of 1 is set as X, it can be more easily determined,
Accuracy is also sufficient.

At this time, the integer part of the number representing the focus state is h11, and the matching number is a.

FIG. 17 is a flowchart illustrating the power focusing operation in the second embodiment.

That is, when the advance button or the retract button of the focusing operation input section 602 is pressed, the power focusing mode is entered, and the first
The position of the group lens 71 is read (F141). Next, the position of the second group lens 72 necessary to know the focus state is read (F142). Next, calculate the number of focus states in the same way as when outputting the number of focus states during zooming (F143) Determine whether it is the advance button or the retract button that is being pressed (F1.44)
).

As a result of this judgment, if the feed button is pressed, the calculated number of retafocus states is decreased (F145). The amount to be reduced should be an amount that has minimal impact when seen by the human eye. Then, calculate the positions of the second group lens 72 and the third group lens 73 corresponding to the new focus state number F146.
), the driving of the second group lens 72 and the third group lens 73 is started (F147). Next, the positions of the second lens group 72 and the third lens group 73 are checked, and if they are in the final position, the driving is stopped (F148 to F151). Then, when both the second group lens 72 and the third group lens 73 have stopped (F152), check whether the focusing operation has stopped (F153). If the focusing operation is still being performed, the process returns to step F145, and the focusing operation is continued. changes, and ends if the operation has stopped. In the case of the renormalization button, the operation is exactly the same (
F 154 to F 162).

FIG. 19 shows the autofocus (A) in the second embodiment.
F) is a flowchart explaining the operation. That is,
When the release button 102 is pressed halfway, the camera enters the AF mode, and first the AF module 58 performs focus detection (F171), and the defocus amount is calculated based on it (F172). Next, the position of the first group lens 71 corresponding to the zoom state and the second lens group indicating the focus state are shown.
The position of the group lens 72 is measured by a counter 55.

552 (F173) Next, the amount of extension of the second group lens 72 is calculated by calculation (F174). That is, coefficients of a plurality of calculation formulas corresponding to the zoom state (position of the first group lens 71) are stored in the ROM 56. In the case of this embodiment, a plurality of sets of coefficients α, β, and γ are stored, and the driving amount ΔX is ΔX−α(β+d)+αφd−(α/ β) is calculated approximately and with sufficient accuracy.

The second group lens 72 that read out the value calculated in this way first
By adding the position information to the position information, the final position of the second group lens 72 and the number of focus states corresponding to that position are calculated (F175°F176). The position of the third group lens 73 is calculated (F177) and the driving of the second group lens 72 and the third group lens 73 is started (F17
8). After starting driving, it is necessary to judge whether the positions of the second group lens 72 and the third group lens 73 have reached the final positions calculated above (F180°F18B), and if they have reached them, they will stop (F181°F184). , if each lens group has already stopped, these are omitted (F 179
°F182). Then, when both the second group lens 72 and the third group lens 73 stop (F185), focus is detected again (F186) and the amount of defocus is calculated.F18
7) After confirming focus (F188), exit.

As described above, according to the second embodiment, even in the case of power focusing that involves driving the lens while looking through the finder, there is no unexpected deterioration of the image due to a shift in the positional relationship of the lens groups, which is similar to the first embodiment. Similarly, by focusing in a floating form that is optimal for the zoom state, the remarkable effect of improving images and expanding the shooting distance range is T.
This can also be achieved with a TL camera, and the extent of this is greater than in the first embodiment due to the use of interpolation calculations.

[Effects of the Invention] As detailed above, according to the present invention, a high-performance zoom lens can be obtained using a focusing mechanism that can take an optimal floating form depending on the zoom state, and it is also possible to reliably suppress aberrations caused by focusing. We can provide a lens driving device that can

[Brief explanation of drawings]

1 to 10 are for explaining the first embodiment of the present invention. FIG. 1 is a block diagram showing an electric circuit, and FIG. 2 is a sectional view of a zoom lens showing the lens configuration and frame configuration. , Fig. 3 is an overview of the camera, Figs. 4 and 5 are block diagrams showing details of the linear ultrasonic motor, Fig. 6 is a block diagram showing details of the drive circuit and switching circuit, and Fig. 7 is a block diagram showing details of the linear ultrasonic motor. Figure 8 shows the movement of each lens group. Figure 8 is a flowchart explaining the zooming operation. Figure 9 is a flowchart explaining the focusing operation. Figure 10 (a) shows the amount of lens group movement relative to the subject distance at wide-angle. Graph, 1st
Figure 0 (b) is a graph showing the amount of lens group movement relative to the subject distance in standard mode, Figure 10 (c) is a graph showing the amount of lens group movement relative to the subject distance in telephoto mode, and Figure 11
The figures to FIG. 18 are for explaining the second embodiment of the present invention, and FIG. 11 is an overview diagram of a single-lens reflex camera, and FIG.
The figure is a block diagram showing the electric circuit, Figure m13 is a flowchart explaining the zooming operation, and Figure 14 shows the basic movement amount of the second to fourth group lenses relative to the first group lens with respect to the extension amount of the first group lens. Graph, FIG. 15 is a graph showing the moving speed of the second to fourth group lenses when the first group lens moves at a constant speed, and FIG. A graph showing the amount of extension of the third group lens from the reference position, FIG. 17 is a flowchart explaining the power focusing operation, and FIG.
The figure is a flowchart illustrating autofocus operation. 511-514...Encoder, 52, ~52410
．． Linear type ultrasonic motor, 531-534...Direction detection circuit, 54.541-544...Drive circuit, 551
~554...up/down counter, 56...RO
M, 57... Arithmetic control unit, 58... AF module, 59... Switching circuit, 601... Zoom operation input unit, 602... Focusing operation input unit, 71...
1st group lens, 72... 2nd group lens, 73... 3rd group lens, 74... 4th group lens, 75... 1st group frame, 76... 2nd group frame, 77... ...3rd group frame, 78...
4th group frame, 80-83... Vibrating body, 84-87... Bearing, 88... Fixed frame, 92, 102... Release button. Figure 3 Patent attorney Jun Tsuboi 13b (A) D (B) Figure 8 (b) Figure (a) $9 Figure (C) Figure 11 Figure 1 of the first group lens Feeding lid 1g14 Figure 15 Figure 16

Claims (1)

[Scope of Claims] A plurality of lens groups including a plurality of focusing lens groups movable in the optical axis direction, a driving means capable of driving each of the plurality of lens groups with different driving amounts, and a focal point of the lens group. a focal length information output means for outputting focal length information corresponding to a distance; and a zoom extension amount of the focusing lens group determined based on the focal length information and a focusing extension amount of each of the plurality of focusing lens groups to be set at the same focusing position. means for making the floating amount different depending on the focal length and determining the focusing extension amount for each focusing lens group based on the focal length information and the focusing position information;
target position output means for outputting a drive target position of the focusing lens group based on the zoom extension amount and the focusing extension amount; 1. A lens driving device comprising: drive control means for driving the lens.