JPH0786585B2 - Lens position control device and optical device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lens position control device in equipment such as a camera and an observation equipment.

[Conventional technology]

Many optical design examples are known as a so-called zoom lens, which is a variable focal length photographing lens used in a video camera or the like. Particularly, the first lens group in front of the optical axis is a lens for focus adjustment, the second lens group is for zooming, the third lens group is for correction, and the second lens group and the third lens group are for correction.
A so-called 4 group in which the fourth group becomes a fixed lens group for image formation by performing a zoom operation by interlocking the groups in a predetermined relationship.
Group zoom can be said to be the most general zoom lens configuration. In this 4 group zoom lens, the 1st group lens group for focus adjustment and the 2nd and 3rd group lens groups for varying the focal length function completely independently, so that the 1st group lens group works in conjunction with zooming.
There is no need to move the group or the second group for focus adjustment. Therefore, the lens barrel mechanism can be achieved with a relatively simple structure.

On the other hand, there is known a so-called inner focus type zoom lens in which the lens groups for focus adjustment are the third and subsequent lens groups. In the case of the inner focus type lens configuration, unlike the above-mentioned four-group zoom lens, depending on the focal length, the closest possible shooting (focusing) is possible when the lens group for focus adjustment is at the most extended position. The distance changes. In particular, at the wide-angle end, there is a great advantage that the 4-group zoom lens can achieve focusing right before the lens, which cannot be achieved. However, on the other hand, in such an inner focus type zoom lens, the lens group for focus adjustment is behind the lens group for zooming, so even if the subject distance does not change, focus can be achieved by zooming. It has a characteristic that the lens group for adjustment needs to be moved. Therefore, there is a drawback that the structure of the lens barrel mechanism becomes very complicated. For this reason, there have been few examples that have been put to practical use in the past. However, in recent years, with the development of the automatic focus adjustment device, a method of directly evaluating the blur of the focal plane and controlling the position of the lens group for focus adjustment based on this information has been put into practical use. By combining the automatic focus adjusting device of this system with the inner focus lens, it becomes possible to set the position of the lens group for focus adjustment to the correct position without taking a complicated lens barrel structure.

5 to 8 show some examples of the inner focus lens. In the type shown in FIG. 5, the first group lens 1 is fixed, the position of the second group lens 2 (solid line) is the position of the focal length on the wide side (wide end), and the position of 2 '(two-dot chain line). Is the position of the focal length (tele end) on the tele side. or,
In this example, the third lens group 3 has a second lens group like the conventional four lens group zoom lens.
The position of 3 (solid line) is the wide end position, and the position of 3 '(two-dot chain line) is the tele end position. The second lens group and the third lens group have the conventional 4
Similar to the lens barrel mechanism configuration of the group zoom, it is linked by a cam ring, for example. 4 is a lens group for focus adjustment, and is configured to be positionally variable in the optical axis direction within a predetermined range defined by an arrow.

In the case of FIG. 6, there is no lens group corresponding to 3 in FIG. Also, in this example, the lens group 4 is the front lens group 4A.
And the rear lens group 4B, the front lens group 4A is fixed, and the rear lens group 4B is configured to be positionally variable in a predetermined range as an optical axis as a lens group for focus adjustment.

In the example of FIG. 7, the first and fourth lens groups 1 and 4 are fixed, and in the second lens group 2, the position 2 is the wide end position and the position 2'is the tele end position. Further, the number of lens groups for focus adjustment is 3, and the position is variable in the optical axis direction within a predetermined range.

In the example of FIG. 8, the first group lens 1 is not fixed, but the first group lens 1 and the second group lens 2 are interlocked with each other during zooming. Here, 1 and 2 indicate the position at the wide end,
Further, 1'and 2'indicate the positions at the tele end. The lens group for focus adjustment is the rear lens group 4B at the rearmost part, as in the example of FIG.

FIGS. 9 and 10 show the relationship between the inner focus lens of FIGS. 5 to 8 and the focal length of the lens group to be used for each focus adjustment (second lens group position). Cage,
FIG. 9 shows the tenth lens of the lens type shown in FIGS.
The figure shows the relationship in the case of the lens type of FIG.
In the figure, the position where the vertical axis is zero is the lens group position for focus adjustment at the tele end ∞ focusing.

As is clear from FIG. 9, in the case of the lens type shown in FIGS. 6 to 8, the close-up distance at which shooting at the wide end (focusing is possible) is 0 m and about 1 m in the middle, the tele end Will be about 0.6m. In the case of the lens type as shown in Fig. 5, it is 0m at the wide end. The close-up distance gradually becomes distant and becomes about 1 m at the tele end.

FIG. 11 shows the basic concept of an example of the automatic focusing apparatus of the type which directly evaluates the blur of the focal plane described above. First
In FIG. 11 (A), 17 is a screen of a video camera or the like, and 18 is a distance measuring visual field which is an area for extracting a signal for performing automatic focus adjustment. Reference numeral 19 is a contrast pattern of the subject. FIG. 11B shows the signal processing, and the luminance signal for the contrast pattern of FIG. 11A is as shown in FIG. When this is differentiated, it becomes like (c), and when it takes an absolute value, it becomes like (d). The height of (e) obtained by sample-holding this is assumed to be A. As shown in FIG. 11 (C), when the lens group position for focus adjustment is plotted on the horizontal axis and the value A is plotted on the vertical axis, a mountain-shaped signal is obtained, and the lens group position (B) at the peak is shown. The focus lens position is reached.

FIG. 12 is a block diagram of a case where the inner focus lens shown in FIG. 6 is taken as an example and combined with such automatic focus adjusting devices 12 and 13. 12 is a sensor, 13
Is an AF circuit that detects the in-focus state by the output of the sensor 12.
Reference numeral 14 denotes a motor which is a drive source of drive means for changing the position of the lens group 4B for focus adjustment in the optical axis direction.

However, in practice, it is often difficult to obtain a focused state at all times, especially during zooming, with the configuration shown in FIG. This is because the automatic focus adjustment devices 12 and 13 detect blurring, determine whether the blurring is mae pin or ato pin, and determine the rotation direction of the motor 14 in the second time for changing the magnification. This is because the movement of only the group lens causes derailment from the locus for continuing to focus on the unique subject distance shown in FIGS. 9 and 10.

In view of this point, Japanese Patent Application No. Sho 63-109966 filed by the same applicant
According to No. etc., the horizontal axis shown in FIG. 9 and FIG.
The map with the lens group position for focus adjustment on the vertical axis is divided into a plurality of blocks (such as I, II ...) As shown in Fig. 13, for example, the center point of each block is The direction and speed of the lens group for focus adjustment during zooming are determined from the differential value of the trajectory and the moving speed of the second lens group 2, and the distance measurement result of the automatic focus adjustment device cannot be obtained. In both cases, it is proposed that the driving means for the second lens group for zooming and the driving means for the lens group for focus adjustment are simultaneously started to eliminate the out-of-focus condition during zooming.

[Problems to be Solved by the Invention]

In the inner focus lens as described above, when the lens group for focus adjustment is at the most extended position as shown in FIGS. 9 and 10, it is possible to shoot (focus) depending on the focal length. Since the closest distance will be different, if the focal length is selected incorrectly, it will not be possible to focus on a focusable subject.

As a method for solving this point, according to Japanese Patent Laid-Open No. 60-143310, it is determined whether or not the distance to the subject determined by the automatic focus adjustment device is closer than the closest focusable distance at that focal length. Has been disclosed, and a method of forcibly zooming the lens group for zooming in the wide-angle direction when the distance is very close is disclosed.

That is, this method is applied when the subject is too close to focus only by moving the lens group for focus adjustment, and is not applied when the subject is in a focusable position. .

Conventionally, when the subject approaches the closest focusable position, focusing is performed only by moving the lens group for focus adjustment,
It took a relatively long time to reach the focus.

An object of the present invention is to shorten the time to reach focusing.

[Means for Solving the Problems]

According to the present invention, when the focusing lens group is closer to the specific position, the focusing lens group is moved to the closer side, and the zooming lens group is also moved to the wide angle side. It is characterized by shortening the time required for focusing.

At first, the focusing lens group was moved to the close-up side, and when the focus was not achieved, the zoom lens group was also moved to the wide-angle side. Deal with normal focusing,
This is because the focusing time is prioritized even if the angle of view is slightly changed only for the subject in the vicinity of the closest point.

〔Example〕

FIG. 2 is a diagram showing the basic idea of the embodiment according to the present invention.

The lens group position for focus adjustment on the vertical axis is divided from 0 to 210 by some encoder means to enable absolute position detection. Similarly, the lens group position for zooming is also 0
It is assumed that absolute position detection is possible up to ~ 180.

The vertical axis moving speed is the moving speed of the lens group for focus adjustment. For example, it is assumed that the 210th address moves in 4.2 seconds (the 50th address.
/ sec). The maximum zooming speed is 18
It is assumed that it moves from address 0 in 6 seconds (address 30 / sec).

Initially, there is a lens group for zooming at the address 50, and if the focus is on the ∞ subject at this focal length, the map upper point P _{1 in} FIG.
The lens group for focus adjustment is located at (about 90). From this state, the subject in front of the lens is panned (or the subject appears in front of the lens). In this case, it is necessary to extend the lens group for focus adjustment when the atopin is detected. Therefore, about 0.04m with the conventional method
P up to ₂ points. Since there are about 120 pulses from P ₁ to P ₂ , the time required during this period corresponds to 2.4 seconds.
At this stage, of course, it is impossible to focus on 0 cm. Therefore, the lens group for focus adjustment by the driving source for driving the lens group for zooming remains zoomed in the wide direction at the address 210. As a result, at the point P _0, the subject immediately before the lens is focused. The time required from P ₂ to P ₀ is 1.7 seconds, so in the conventional method, the total time from P ₁ to P ₀ is calculated.
It will take 4.1 seconds.

On the other hand, the basic idea of the present embodiment is to initially focus only the lens group for focus adjustment. Then, even if you move it to P ₅ (closest to 1 m for normal shooting), it will not focus, so move the lens group for zooming to the wide-angle side as well, move from P ₅ to P ₃ , and then move to P ₃ . Reach ₀ points. The time required during this period is 2.4 seconds. Therefore, compared to P ₁ → P ₂ → P ₀ , P ₁ → P ₅ → P ₃ →
41% reduction in time can be achieved with P ₀ . However, for example, when panning from an ∞ subject to a subject of 0.04 m, it takes 2.4 seconds for P ₁ → P ₂ in the conventional example, but focusing can be achieved without fluctuation of the focal length. On the other hand, in the present embodiment, the focus is 0.04 m at the point P ₄ , and the time is about 1 second during this period. Therefore, the time can be shortened by 50% or more, but the focal length varies. The present invention is not suitable when such a variation in focal length is disliked. However, since the relationship between the second lens group position and the focal length is actually as shown in FIG. 3, the focal length at P ₁ is 14 mm and at P ₄ is 11 mm. With such a change in the focal length, the change in the angle of view is hardly noticeable, and it is considered that the effect of shortening the time to reach the focus is more advantageous.

The basic idea of this embodiment has been described above.

Next, examples will be specifically described.

FIG. 4 is a diagram showing the movement locus of the lens in the map of the first embodiment.

Most of the conventional four-group zoom lenses have a closest shooting distance of about 1 m, and a distance shorter than this is a so-called macro shooting area. Based on this idea, the first embodiment of the present invention has a region 16 using both the zoom motor and the focusing motor and a region 17 using only the focusing motor as the motors used for focusing as shown in FIG. Split into. In this case, the area 17 in which focusing is performed only by the focusing motor is an area surrounded by the ∞ locus and the 1 m locus 58. That is, when adjusting the focus between 1 m and ∞, the focal length does not change. Here, the upper limit of the region 17 is set to a 1 m locus, and one of the reasons for this is as shown in FIG.
This is because the subject distance of 1 m is the closest shooting distance at all focal lengths.

For example, if the focus is infinity at P ₁₃ point and the subject immediately before the lens is focused, the path P ₁₃ → P ₁₄ → P ₁₅ → P ₀ will be followed.

Thus, in the first embodiment, the boundary between the regions 16 and 17 is the line 58. As a result, focusing is performed in the range from ∞ to a certain distance (1 m in FIG. 4) defined by the line 58 without changing the focal length.

In Fig. 14, P ₁₀ , P ₁₃ , P ₁₆ , P ₁₉ , P ₂₂ , and P ₂₄ in Fig. 4 are taken as infinity at several focal lengths, and P ₀ (0 m focus) from this position. It shows the path to. For example, P
_When focusing on a subject at 0 m from the _{16 in-} focus positions, first drive only the focusing motor to the 1 m line, and then drive both the focusing motor and the zoom motor. Going to ₁₈ points, the lens group for focus adjustment hits the near end here, so from now on, only the zoom motor is driven to reach P ₀ point which is the ₀ m in-focus position.

In FIG. 15, the encoder for detecting the focal length is not a subdivision such as T to W180 division as shown in FIG.
The case of division is shown. In this case, the boundary line 58 in FIG. 4 becomes 58 '.

FIG. 1 shows a block diagram of this embodiment. In this example, as the lens type, a type in which the first group lens 1 and the second group lens 2 move during zooming shown in FIG. 8 is used. 18 is a lens frame of the second lens group 2. 19 is a brush integrally attached to the lens frame 18. Reference numeral 20 denotes an encoder board, which constitutes an encoder (zoom encoder) for detecting the focal length (position detection of the zoom lens). Reference numeral 23 is a zoom encoder reading circuit, and the detection result is fetched by the CPU 33.
As the zoom encoder means, here, a brush 19 is formed on the resistance pattern or the gray code pattern on the substrate 20.
Although the sliding type is shown, other methods may be used.

21 is an image pickup device such as a CCD. Reference numeral 22 denotes an AF device that obtains the value of A using the luminance component of the image pickup signal, for example, in the case of the method shown in FIG. 11, and the result is taken into the CPU 33. twenty five
Is a drive pulse output circuit for the focusing motor 27, and this drive pulse is determined by the CPU 33. 26 is a driver. 27 is a focusing motor composed of a step motor. Reference numeral 24 is a drive pulse counting circuit for the focusing motor 27, which forms an encoder for knowing the absolute position of the lens group for focus adjustment. In order to use the number of steps for absolute position detection, the main
When the SW31 is turned on, the power-on reset circuit 30 moves the lens group 4B for focus adjustment to a predetermined position, and for example, the initial reset is performed by setting the number of steps at this predetermined position to zero. 28 is a driver for the zoom motor 29, and 29 is a zoom motor. Regarding the drive of the zoom motor 29, the CPU 33 also determines the drive content. A zoom switch 32 has a wide-angle direction switch (W) and a telephoto direction switch (T). 34 to 36 are data for determining the speed and direction of the focusing motor 27 during zooming described above. Areas such as I, II ... in FIG. 13 are discriminated from the area data 36 based on the zoom encoder detection result and step number information, and then the operation contents of the zoom switch 32,
From this region (I, II ...) The direction of rotation of the focusing motor 27 is determined from the direction data 35. The rotation speed is also determined from the speed data 34.

Conventionally, when the zoom switch is not operated, the CPU determines the driving direction and speed of the focusing motor based on the detection result of the AF device, and based on these results, the focusing motor drive pulse output and focusing motor driver. Drives the focusing motor. On the other hand, in the present embodiment, even if the zoom switch 32 is not operated, the CPU 3 determines whether the zoom switch 32 and the step number are in the area 16 or the area 17 in FIG.
Determined within 3. In the case of the region 16, the zoom motor 29 and the focusing motor 27 are both driven according to the detection result of the AF device 22, as described above.

FIG. 16 is a flowchart of the first embodiment. Here, a selection flow of a motor used for focusing is shown. Start at step 39. In step 40, it is determined whether the zoom operation switch 32 shown in FIG. 1 is operated. During the zoom operation, jump to the zooming routine 52. The zooming routine is disclosed, for example, in Japanese Patent Application No. 63-109966 by the same applicant. If the zoom operation is not performed, the value of the zoom encoder is read in step 41. Then step 42
At, the number of steps of the focusing motor 27 is read (absolute position information of the lens group 4B for focus adjustment is read). In step 43, the focus / non-focus of the AF device 22 is determined. If in focus, go to step 44 to zoom motor
Both 29 and focusing motor 27 are stopped. If out-of-focus, step 45 reads whether the direction of out-of-focus is mae pin or ato pin. The driving directions of both motors are determined by the points in the map which are found from steps 41 and 42 and the reading result. Here, if the following flow is proceeded in the case where the out-of-focus is the mae pin, it is determined in step 46 whether the current point in the map is in the area 16 or the area 17 shown in FIG. . If it is the region 16, it is determined in step 47 whether it is the wide end or not, and in step 49 it is determined whether or not it is at the most extended position. The focusing motor 27 only, the zoom motor 29 only, and both motors are driven. The maximum position is stored in advance in the CPU 33 as the number of steps, and it is determined by comparing the current number of steps with the value. The zoom encoder also determines the wide end of the zoom.

Further, in step 53, it is judged whether or not it is in the area 17.
If it is No, it means that it is in a prohibited area such as a super-infinite area (hatched area in FIG. 4). Therefore, it is necessary to escape the prohibited area at 54, though not described in detail here.

At step 55, it is judged if the lens group for focus adjustment is at the most extended position. If yes, step 56
Then, the zoom motor 29 is driven to enter the area 16. On the other hand, if No, the focusing is performed only by the focusing motor in step 57.

With the above configuration, (A) no matter what the focal length at the time of focusing is,
It is possible to focus on the subject immediately before the lens.

(B) The time taken to focus on the subject can be greatly shortened.

(C) Up to the normal shooting area (for example, 1 m) on the closest side, focusing is performed only by the focusing motor as before, and the focusing motor and the zoom motor are used for the closest subject that still cannot be focused. Since both are driven, it is possible to achieve focusing without a sense of discomfort.

[Embodiment 2] A case where the optical system of FIG. 5 is used will be described. In the optical system of FIG. 5, the curve 58 of the 1-m locus (the line connecting the in-focus points to the 1-m position at each focal length) is different from that of the first embodiment shown in FIG. The basic idea of motor control is the same.

That is, as shown in Fig. 17, focusing is performed only by the focusing motor from the infinity position to the 1 m locus, and the focusing motor and the zoom motor are used for the closest subject that is still out of focus. Both are driven to focus.

For example, when focusing on a subject at 0 m from the P ₃₃ point at the infinity position, only the focusing motor is driven up to the 1 m focus position at the P ₃₄ point, and the focusing motor is moved from there. Both the zoom motor and the zoom motor are driven at the wide angle end
Move to point P _35, and then switch to driving only the focusing motor and move to point P ₀ where ₀ m can be focused.

It should be understood that both motors are drive-controlled depending on which one of the regions 16 'and 17' is used even when starting from a position other than the infinity focus position.

In the block diagram for realizing the second embodiment, the lens group moved by the focusing motor 27 in FIG. 1 is replaced with the fourth lens group 4 in FIG. 5, and the zoom motor 29 is used. It is only necessary to replace the lens group moved by (4) with the second and third lens groups 2, 3 shown in FIG.

Note that the flowchart is shown in FIG. 18 because some changes are necessary. Explaining the steps different from those in FIG. 16 by giving different reference numerals, it is determined in step 46 'whether they are in the area 16' or the area 17 'shown in FIG. If it is in the area 16 ', the operation proceeds to step 47, where the same operation as that of the first embodiment is performed, and if it is in the area 17', the step is performed.
Go to 60. In step 60, only the focusing motor 27 is driven to perform focusing.

[Third Embodiment] A third embodiment shown in FIG. 19 relates to the control of the motors 27 and 29 in the area 16 and aims to suppress the change in the angle of view to a certain ratio or less. Therefore, the substantial speed ratio of the focusing motor 27 and the zoom motor 29 is changed depending on the position of the lens group. Specifically, referring to FIG. 19, the zoom lens group (first embodiment and when describing in the same optical system) has been started from ∞ position, in the case of P ₄₁ point position, as in the case of P ₅₆ point position, focusing motor 2
The ratio of the speed of the zoom motor 29 to the speed of 7 is changed. Specifically, set the P ₄₁ point closer to the wide-angle end to P ₅₆
The speed ratio of the zoom motor 29 is set higher than that of the point position. In other words, at the point P ₄₁ near the telephoto end,
As shown in FIG. 3, the focal length varies greatly with the movement of the zoom lens group, so if the zoom lens group is varied too much, the angle of view changes greatly. The speed ratio of the motor 29 is reduced. Each P ₄₀ points For reference, P ₄₃ points, P ₄₆ points, P ₄₉ points, P ₅₂
Move the lens group from points, P ₅₅ points, P ₅₈ points, P ₆₁ points, P ₆₄ points, ...
, It is easy to understand the difference in speed ratio between the focusing motor 27 and the zoom motor 29 due to the difference in inclination angle.

The concept of the third embodiment can be applied to the optical system shown in FIG.

[Fourth Embodiment] The concept of the fourth embodiment is that the focusing motor is independent.
It is characterized in that switching to driving both the focusing motor and the zoom motor is performed depending on time. That is, in the above-described first to third embodiments, the position of the lens group for focus adjustment (for example, the focus position of 1 m) is the switching point of the motor control, but in the fourth embodiment, the focus by only the focusing motor is used. When focusing is not achieved even after a lapse of a predetermined time in focusing, focusing is performed by driving both the focusing motor and the zoom motor.

If you set the drive time of the focusing motor alone as the timer time, assuming that the subject in general shooting is often around 2 m, and from there it moved to close-up shooting around 1 m of normal level, It is possible to obtain substantially the same effects as those of the above-described first to third embodiments.

A fourth embodiment will be described with reference to FIG. This FIG. 21 is an example in which the optical system of FIG. 6 to FIG. 8 is implemented, and when focusing from the initial position to the near side, first, only the focusing motor is driven for a predetermined time, and still After a lapse of a predetermined time when focusing is not performed, both focusing motor and zoom motor are switched to focus. For example, if the initial position is the 2m focus position that is between ∞ focus and 1m focus
_If you focus on a subject 0m from ₇₀ points, P ₇₀
Drive only the focusing motor for a predetermined time from the point
It moves to P ₇₁ , drives both focusing motor and zoom motor from there, and moves to P ₇₂ point where it hits the wide angle end, so from now on only focusing motor will be driven P ₀ Move to the 0m focus point. Similarly, if the starting from P ₇₃ points in ∞ focus position until P ₇₄ point becomes a driving of the focusing motor only from P ₇₄ point to P ₇₅ points in both the focusing motor and the zoom motor drive From point P _{75 to} point P _0, only the zoom motor is driven.

The block diagram for realizing the fourth embodiment is the same as that shown in FIG.

The flow chart is partly different from that shown in FIG. 16. Therefore, the flow chart as the fourth embodiment is shown in FIG.

With respect to each step, the description of the same steps as those in FIG. 16 is omitted, and different steps will be explained. If it is post-focus, it branches to another post-focus routine. Then, only when the subject is in front of focus, proceed to the following step 47. When the zoom lens group is not at the wide-angle end and the focus adjustment lens group is not at the most extended position, the flow proceeds to a mae pin (front focus) routine. The mae pin routine will be described below.

[Step 70] Reset the timer and start immediately.

[Step 71] Only the focusing motor 27 is driven for focusing.

[Step 72] See if focusing can be obtained by driving only the focusing motor 27. When focus is detected, step
Proceed to 73, and if out of focus, proceed to step 74.

[Step 73] Since the subject is in focus, the focusing motor 27 is stopped.

[Step 74] Determine whether the timer has counted a predetermined time, and proceed to step 75 when the predetermined time has been measured,
If not done yet, return to step 71.

[Step 75] Since the subject is located closest, both motors 27 and 29 are driven to shorten the time until focusing.

[Step 76] It is detected whether or not the zoom lens group hits the wide-angle end. If the wide-angle end is detected, the process proceeds to step 77. Otherwise, the process proceeds to step 80.

[Step 77] Only the focusing motor 27 is driven to perform focusing.

[Step 78] It is detected whether or not the object is in focus. When the object is in focus, the operation proceeds to step 79, and when the object is out of focus, the operation proceeds to step 80.

[Step 79] Focusing motor 27 because it is in focus
To return to the original "START" flow.

[Step 80] Check whether or not the focusing lens system is at the most extended position. If it is at the most extended position, proceed to step 81. If not, proceed to step 84.

[Step 81] Since the focusing lens group is at the most extended position, the focusing motor 27 is stopped,
Only the zoom motor 29 is driven to focus only with the zoom lens group.

[Step 82] It is detected whether or not the object is in focus. When the object is in focus, the operation proceeds to step 83, and when the object is out of focus, the operation returns to step 81.

[Step 83] Since the subject is in focus, the zoom motor 29 is stopped and the original “START” flow is returned to.

[Step 84] It is detected whether or not the subject is in focus, and when the subject is in focus, the process proceeds to step 85, and when the subject is out of focus, the process returns to step 76.

[Step 85] Since the focus is achieved, both motors 27 and 29 are stopped and the original "START" flow is returned to.

A feature of the fourth embodiment is that, when the movement of each lens group for focus adjustment is controlled, the interval for independently driving the focusing lens group is controlled based on time. Therefore, when focusing on the close-up side, the focusing lens group is independently moved to the close-up side for a predetermined time as in the conventional case, and the focusing focus is set on the close-up subject that still cannot be focused. The zoom lens group was also moved to the wide-angle side according to the lens group.

While the first to third embodiments described above are switched based on the position information of the focusing lens group, the fourth embodiment is switched based on the time information, which is a slightly different concept. However, if the focusing lens group is located in the normal photographing area, as is clear from FIG. 21, the operation of the fourth embodiment is almost the same as that of the first to third embodiments. Therefore, the same effect can be obtained.

Note that, in the fifth embodiment shown in FIG. 22, the same control as that of the fourth embodiment is carried out by the optical system of FIG.

This fifth embodiment can also be performed by the same control as the above-mentioned fourth embodiment,
The only modification is the modification of the optical system shown in FIG.

Although not described in detail, in the fourth and fifth embodiments, it is also effective in practice to change the independent driving time of the focusing motor 27 according to the position information of the zoom lens group. This is, for example, to set the "predetermined time" to be short when the zoom lens group is located on the wide-angle end side.

In addition, it is also effective to apply the idea of the third embodiment to the fourth and fifth embodiments.

〔The invention's effect〕

According to the present invention, by moving the zoom lens group at the time of focusing, it is possible to shorten the time required for focusing and focus on the closest subject. Also, in this operation, in the shooting area that is often used, the focusing operation is performed without changing the angle of view by the operation of the focusing lens group alone, so the lens position that does not cause a sense of discomfort in shooting A control device and an optical device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall construction of an embodiment of the present invention. FIG. 2 is an explanatory diagram showing respective positions for focusing of the zoom lens group and the focus adjustment lens group. FIG. 3 is an explanatory diagram showing the relationship between the position of the zoom lens group and the focal length. FIG. 4 is an explanatory view showing a focusing locus in the first embodiment. 5 to 8 are views each showing an inner focus type lens optical system. FIG. 9 is an explanatory diagram showing the characteristics of the lens optical system shown in FIGS. 6 to 8. FIG. 10 is an explanatory diagram showing the characteristics of the lens optical system of FIG. FIG. 11 is an explanatory diagram showing the principle of a general automatic focusing device used in this embodiment. FIG. 12 is a simple explanatory view of a state in which the inner focus lens and the automatic focusing device are combined. FIG. 13 is an explanatory diagram showing an example of area division when the number of divisions of the zoom encoder is small. FIG. 14 is an explanatory view summarizing focusing trajectories in the first embodiment shown in FIG. FIG. 15 is an explanatory diagram showing regions in which motor control is different in the region division of FIG. FIG. 16 shows the flow chart of the first embodiment. FIG. 17 is an explanatory view showing a focusing locus in the second embodiment. FIG. 18 shows the flow chart of the second embodiment. FIG. 19 is an explanatory view showing a focusing locus in the third embodiment. FIG. 20 is an explanatory view showing a focusing locus in the fourth embodiment. FIG. 21 is a flow chart of the fourth embodiment. FIG. 22 is an explanatory view showing a focusing locus in the fifth embodiment.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03B 13/34

Claims (4)

[Claims] 1. A first lens group that moves along an optical axis for zooming, a second lens group that moves along an optical axis for focusing, and positions of the second lens group are detected. Position detecting means and control means for controlling the movement of the first and second lens groups, and the control means needs to move the second lens group to the closest side for focusing. If it is detected that the position of the second lens group is closer to the specific position than the specific position, it is possible to move the second lens group to the closest position and simultaneously move the first lens group to the wide angle side. Characteristic lens position control device. 2. A first lens group that moves along the optical axis to perform zooming, a second lens group that moves along the optical axis to perform focusing, and the first and second lens groups. And a control means for controlling the movement, wherein the control means moves only the second lens group to the close-up side for a predetermined time when the second lens group needs to be moved to the close-up side for focusing. And a lens position control device for moving the first lens group to the wide-angle side at the same time as moving the second lens group to the close-up side when the subject is still out of focus. 3. A first lens group that moves along the optical axis to perform zooming and a second lens group that moves along the optical axis to perform focusing.
A zoom lens having a lens group, a position detecting means for detecting the position of the second lens group, and a control means for controlling the movement of the first and second lens groups, the control means comprising: In order to focus, it is necessary to move the second lens group to the close side, and when it is detected that the position of the second lens group is closer to the specific position, the second lens group is moved to the close side. And an optical device which moves the first lens group to the wide-angle side at the same time. 4. A first lens group which moves along the optical axis for zooming and a second lens group which moves along the optical axis for focusing.
A zoom lens having a lens group, and control means for controlling the movement of the first and second lens groups are provided, and the control means moves the second lens group to the close-up side for focusing. If it is necessary, only the second lens group is moved to the close-up side for a predetermined time, and if the focus is still not reached, the second lens group is moved to the close-up side and at the same time, the first lens group is moved.
An optical device that moves the lens group to the wide-angle side.