JPH01307710A - Lens position controller for optical equipment - Google Patents

Abstract

PURPOSE:To omit to discriminate a nonfocusing direction and to speed up focusing by determining a representative speed so that a 2nd lens group becomes out of focus in a specific direction. CONSTITUTION:A 1st group lens 1 is fixed to a lens frame 103, engaged with a fixed lens barrel 102 threadably at the best lens position, and fixed with a screw 104 after being adjusted. A 2nd group lens (variator) 2 is fixed to a variable moving ring 105 and moves in a thrust direction (optical-axis direction) under the guidance of a bar 108. Then the representative speed of the 2nd lens group 2 which serves for both correction and focusing is set to a front or rear focus state so as to obtain an out-of-focus state. Consequently, the correcting direction can be determined unequivocally and the time required to discriminate the correcting direction is omitted; and the response time up to focusing is shortened and a program is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens position control device for optical equipment such as cameras and observation equipment.

[Prior Art] Conventionally, a zoom lens mounted on a video camera has generally been composed of four lens groups as shown in FIG.

In Fig. 9, 1 is the 1st group lens F located at the tip of the lens barrel for focusing, 2 is the 2nd group lens V which is a variator lens for changing the magnification, and 3 is the focal point after the magnification changing operation. The third lens group C, 4, which is a convencator lens for properly converging the images, is the fourth lens group R1, which is a relay lens for forming an image. Note that the zoom lens shown in Figure 1 shows the focal length of the zoom lens at the wide end (shortest), and (
1) This is a diagram in which the subject is in focus at a distance. Below, in order to explain how each lens group moves, we will show the positions of the 1st group lens F, 2nd group lens V, and 3rd group lens C in this state. are each considered to be the zero (0) position.

10 to 12 show the relationship between the position change of each lens group FR and the focal length or subject distance of the zoom lens. The characteristics of the zoom lens will be explained below with reference to these figures.

FIG. 10(a) shows the focal pressure when the second group lens V is moved, with the horizontal axis representing the position where the second group lens V is moved along the optical axis, and the vertical axis representing the focal length f of the zoom lens. @
It is a graph showing how f changes. Note that W represents the wide-angle state where the focal length of the zoom lens is the shortest, and T represents the telephoto state where the focal length of the zoom lens is the longest.

In FIG. 10(b), the horizontal axis represents the position of the third group lens C in the optical axis direction, and the vertical axis represents the focal pressure of the zoom lens! It is a graph showing the change in the focal pressure 11f with respect to the change in the position of the third group lens C by taking If.

Figure 11 shows the distance to the subject Il! The horizontal axis is the reciprocal of (meters), and the vertical axis is the position when the first lens group F is moved forward along the optical axis direction, and the change in subject distance with respect to the change in the position of the first lens group F. FIG.

In Figure 12, the position when the first lens group F is moved forward along the optical axis is plotted on the vertical axis, and the focal pressure @f of the zoom lens is plotted on the horizontal axis. 1! Il
In addition to showing the relationship with f, the distance to the subject is in, 2
It is a graph illustrating the position of the first lens group F for each case of m13m%■.

From the above figures, it can be seen that known zoom lenses have the following characteristics. That is, Figures 11 and 12
As is clear from the figure, when the subject distance does not change, there is no need to move the first group lens F even when zooming and changing the focal length, so the second group lens V and the third group lens C and C in accordance with the characteristics shown in FIG. 10, it is relatively easy to control the position of each lens, and the advantage is that the position control can be performed by a mechanical control mechanism such as a cam.

Figure 13 shows the second group lens 2 (variator lens) and third group lens 3 (convencator lens) of a known zoom lens.
It is a diagram showing an interlocking mechanism with. In the same figure, 5 is 2
A second group lens holding frame holds the group lens 2, a third group lens holding frame 6 holds the third group lens 3, and 7 and 8 guide the lens holding frames 5 and 6 along the optical axis. A guide bar 9 is a pin 5 protruding from the lens holding frames 5 and 6.
a cam cylinder having cam grooves 9a and 9b drilled on its circumferential surface into which the cam grooves 9a and 6a are inserted; 10 a fixed cylinder fitted on the outer periphery of the cam cylinder and fixed to a stationary member such as a lens barrel;
Reference numeral 11 denotes a zoom operation ring which is fixed to the cam cylinder 9 through a connecting portion 11a and fitted so that it can only rotate relative to the outer peripheral surface of the fixed cylinder 10. Zoom operation ring 1 when zooming
1 is rotated, the cam cylinder 9 is also rotated, and as a result, the relative position of the pin 5a within the cam groove 9a and the relative position of the pin 6a within the cam groove 9b change.
and the third group lens holding frame 6 are moved relative to each other along the optical axis direction.

However, the conventionally known control mechanism using a cam cylinder has the disadvantage that the manufacturing cost is high because the precision of the bottom metal of the cam cylinder and the machining accuracy of the cam groove must be extremely high.

Moreover, as is clear from Figs. 11 and 12, conventional zoom lenses do not allow close-up distance*<for example, 1 m or less).
In order to focus on the subject, the amount of extension of the first group lens 1 must be increased in proportion to the reciprocal of the distance, and to focus just in front of the lens, it must be extended by an almost infinite amount, so it is very close. A major drawback was that it was impossible to take pictures at a distance.

Therefore, recently, a so-called inner focus type zoom lens has been proposed, which allows focusing without moving the first lens group 1.

As shown in FIG. 14, an example of this zoom lens has a first group lens 1 and a second group lens 2, but does not have a third group lens corresponding to a conventional convencator. In this zoom lens, the 1st group lens 1 and the front lens 4A of the 4th group lens are
(R) is configured as a non-moving lens, while the variator of the second group lens 2 is configured to be moved when changing the focal length, similar to the known zoom lens shown in FIG. Also, the rear lens 4B (RR
) has the function of performing focus adjustment and correction like the convencator lens of a conventional zoom lens, and the focal point is adjusted by moving the lens 4B along the optical axis like a conventional convencator lens. Adjustments and corrections are made.

Further, as another example of the structure of the inner focus type zoom lens, there is an example as shown in FIG. 17. In this case, the second lens group 2 has a variable magnification function in a four-group configuration, similar to the conventional four-group zoom shown in FIG. However, what is different from FIG. 9 is that the first group 1 is attached and fixed to a fixed lens barrel 101.

For this reason, the third group lens 3, which conventionally only had a correction function,
This also serves as a focusing function.

A zoom lens with such a lens configuration does not have the first group lens 1 working eight times, so it is possible to focus on extremely close objects, but the second group lens 2, which is a moving lens, relay rear lens 4
Since the relative positional relationship with the third group lens 3 in the case of B or 17 is extremely complicated, a simple control mechanism such as a cam mechanism as shown in FIG. or the third lens group 3 shown in FIG. 17, it is extremely difficult to put into practical use a zoom lens having the lens configuration shown in FIG. 14 or 17 using only a mechanical mechanism. Ta.

In FIG. 15, the horizontal axis represents the position of the second group lens (V) in the zoom lens shown in FIG. 14, and the vertical axis represents the position of the relay rear lens 4.
This is a graph showing the relative positional relationship between both lenses for each subject distance, taking the position of B (RR). m, 1 m, 0.5m, 0.2m
, 0.01 m, it is found that it is impossible to control both lenses by a simple control mechanism such as a cam.

However, recently, the zoom lens shown in FIG. Proposals have been made to put this into practical use, and products developed based on these proposals have also been announced.

FIG. 16(A) is a schematic diagram illustrating the lens position control method and lens configuration adopted in the proposal or product, where 1 is the first group lens, 2 is the second group lens, and 4A is the front lens of the relay lens. , 4B is the rear lens of the relay lens, 12 is an image formation detection means in the focal plane, 13 is a focus control (AF) circuit for focus detection and focus control, 14
is controlled by the AF circuit 13 and the relay rear lens 4B
This is a driving means for positioning and driving.

FIGS. 16(B) to 16(D) show an example of an automatic focus adjustment device. In FIG. 16(B), 17
It is assumed that 18 indicates the entire screen area of the video camera, 18 indicates the range from which a signal is extracted for distance measurement, and 19 indicates the contrast that the subject actually has. Figure 16 (C
), if (a) is this contrast part, (b) is the Y signal output, (c) is the differential value of the Y signal, (d) is its absolute value, and (e) is the peak. This is a held signal, in which the height A indicates the degree of focus (hereinafter referred to as blur evaluation value). In Fig. 16 (D), the lens position of the first group lens 1 in Fig. 9 or lens 4B in Fig. 14 is plotted on the vertical axis, and the blur evaluation value A is plotted on the vertical axis, and the focus is at the peak position B. will be realized.

In addition, as another improved method, Japanese Patent Application Laid-Open No. 62-2961
No. 10, Japanese Unexamined Patent Publication No. 62-284316, etc. have been proposed. This is the position information of the variator lens and the lens that also serves as a compensator and focus function, or
According to the positional information of the variator lens and the distance operation member (distance ring), a unit movement amount of a lens that also serves as a compensator and a focus function (hereinafter referred to as a dual-purpose lens) corresponding to a predetermined movement amount of the variator lens is memorized. The movement of the dual-purpose lens is controlled based on the unit movement amount that is stored every time the variator lens moves by a predetermined amount.

[Problems to be Solved by the Invention] By the way, in the known zoom lens and lens position control method shown in FIG.
If the accuracy and speed of the input signal to the F circuit 13 are high, there will be no blurring or distortion in the image produced on the imaging plane, but in reality, the control accuracy of the relay rear lens 4B may be affected due to response delays in distance measurement cycles, etc. Since there is a very high possibility that the image quality will be low, there is a serious drawback that large blurring is likely to occur.

In addition, in the above-mentioned improved method, the premise is to detect a predetermined amount of movement of the variator lens, so in order to obtain highly accurate movement of the above-mentioned dual-purpose lens, the amount of movement of the variator lens must be made extremely small. Furthermore, there is a concern that the moving speed of the dual-purpose lens should not be increased, and that it would take a considerable amount of time to correct the blur that has occurred.

Therefore, an object of the present invention is to provide a zoom lens that does not cause large blurring even if there is a response delay such as a distance measurement cycle, and also does not cause large blurring even if the variator position is not detected very precisely. An object of the present invention is to provide a lens position control device that can be configured.

[Means for Solving the Problems] A lens position control device of the present invention includes a first lens group that moves along the optical axis to perform a magnification change function, and a first lens group that performs a magnification change function and a correction and focusing function during a magnification change. a second lens group for performing
lens group position detection means for detecting the position of the first lens group and the position of the second lens group, respectively; and a lens group position detecting means for detecting the position of the first lens group and the position of the second lens group; drive control means for controlling based on focus/out-of-focus determination from the focus detection means, the drive control means controlling the first
and stores representative speed information of a plurality of second lens groups set to be out of focus in a specific direction according to the position information of the second lens group and the 8-motion speed information of the first lens group. At the same time, a second lens group movement information storage unit that stores correction information for correcting the representative speed; and second lens group drive control means that drives and controls the lens group until the lens group is in focus based on the correction information and when out of focus is detected, and then controls the drive until the lens group is detected as out of focus based on the representative speed information. This is a special feature.

[Function] In the present invention having the above-described configuration, since the representative speed is determined so that the second lens group is out of focus in a specific direction, the second lens group when it is determined to be out of focus is Correction of the group is determined in a simple manner, and the determination of out-of-focus directions can be omitted, allowing quick focusing.

[Example] The apparatus of the present invention will be described in detail below based on an example shown in the drawings.

Embodiment 1 FIG. 1 shows a cross-sectional view of a zoom lens barrel using Embodiment 1 of the lens position control device according to the present invention.

In the figure, 1, 2.4A, and 4B are lens groups already explained in FIG. 14. The first group lens 1 is fixed to a lens frame 103, screwed together with the fixed lens barrel 102 so that the lens position is optimally positioned, and fixed with screws 104 after adjustment. The variator 2 is fixed to the variator movement 3j1105 and moves in the thrust direction (optical axis direction) using the bar 108 as a guide. Here, the bar 108 is machined with a V-groove with a lead on the outer periphery as shown in the figure, and a ball (not shown) is pressed into this V-groove by a plate spring (not shown) fixed to the variator moving ring. The position is determined by
By rotating the bar 108 using the zoom motor 140 shown in the figure, its position can be changed. Also,
A brush 107 is attached to this movable ring and forms a variator encoder by sliding between it and the encoder board 106.

Reference numeral 109 denotes an iG meter, which controls the aperture diameter by driving blades 111. Lens group 4A is lens barrel 1
It is fixed at 1B.

On the other hand, the lens (RR) 4B is attached to a movable ring 117, and the movable ring 117 is integrally provided with a sleeve 115 that is internally threaded and extends in the optical axis direction. A drive shaft 11 with a male thread machined on the outer periphery that cannot move and can rotate around the optical axis.
4 is screwed together. This drive shaft 114 has a drive shaft pulley 113a at one end, and rotational driving force is transmitted through a V-belt 120 that is hooked between the drive shaft pulley 113a and a pulley 113b of the step motor 112. That is, by rotating the step motor 112, the drive shaft 114 rotates, and the sleeve 115 is screwed out and screwed into the lens group 4B.
This means that the position in the optical axis direction can be changed.

Here, for example, the pitch of the screws of the sleeve 115 is set to 9.3.
5mm, and the ratio of drive shaft pulley 113a to pulley 113b is 2. When the rotation angle per one pulse of human power of the step motor 112 is 18 degrees, the step motor 11
When applying one pulse to 2, lens group 4B becomes 8.75 μm.
Although it will move in the optical axis direction, if the effect amount on the image sensor 129, which is the focal plane due to the 8th shift of the lens group 4B, is set to about 1.0, it will move by one pulse from the time of focus. Even if the lens group 4B shifts, the circle of confusion that occurs is about 10 μm, and with this level of precision, sufficient focusing precision can be obtained.

In this embodiment, the number of input pulses of the step motor 112 is used to detect the position of the lens group 4B, which has both the convencator and focus functions. It is necessary to move it to a predetermined address 0, and in this embodiment, the rear end portion 122 of the moving ring 117 is the O address adjustment cam! It is configured so that the location corresponding to 21 is address 0.

In the zoom lens system configured as described above, the relative relationship between the position of the second group lens 2 (hereinafter referred to as V) and the position of the relay rear lens 4B (hereinafter referred to as RR) is as follows. It is expressed as shown in the chart of FIG. 5 according to the object distance.

In FIG. 5, it is assumed that the point where the position of RR and the position of V are respectively detected by the position detection means is Pl, and the distance measurement cycle in the focusing control means that controls this zoom lens is 1. Suppose it was. Assuming that the distance measurement cycle is started at the same time as the movement (2) is performed, it is considered that the positional relationship between V and RR will change to point P until the next distance measurement result is obtained.

On the other hand, if you move RR at the same time as ■ moves,
For example, even if correction by distance measurement is not performed, the relative positional relationship between V and RR will be the value represented by point P3, and as a result,
The deviation from the ideal point P4 is d2. For example, if the effect of V on the focal plane at the focal lengths P1 to P4 is expressed as 1.0, and if the F number at this time is F, then the diameter of the circle of confusion that occurs is zero at point P4, and the diameter at point P4 is zero. In P3, d, /
F, and d, /F at point P2. Here, dl = 5d
2, the blurring at points P2 and P4 appears as a difference of five times in the circle of confusion. Although this movement is required under the assumption that there is no change in subject distance, it has a significant effect on improving the incidence of blur during zooming.

However, in order to ideally realize this idea, V
It is necessary to accurately find the position of RR and find point P+, correctly predict the characteristic curve passing through point Pl, and then calculate the required moving speed of RR, which requires large-scale calculations. As a result, a problem arises in that a large-scale arithmetic circuit is required and the cost of the focusing control means becomes high.

Therefore, in this embodiment, the map shown in FIG. 5 is divided into both the V direction and the RR force direction according to the required accuracy, and the representative speed in each region is stored in the speed data memory shown in FIG. A method is adopted in which the information is memorized within the 131.

FIG. 6 shows an example in which the map in FIG. 5 is divided into regions. In this division example, while the movement of V is divided equally, it is divided by the difference in slope between the trajectory (1) passing within one area in the RR force direction V and the closest trajectory divided by the target depth of field. ing.

FIG. 7 is a diagram for explaining a control system already proposed by the present applicant, which calculates the moving speed of RR from the relative position curve between V and RR within the regions (1) and (II) of FIG. 6.

In Fig. 7, 23 is a relative position curve passing through point P% when the subject distance is constant, and curves 2° and 21 are the slopes of lens movement in the respective regions.When the moving speed of the variator is constant, (can be considered as the moving speed of RR), from point P to V without feedback from AF.
and if RR moves, region I! While in region I, it moves along a trajectory parallel to curve 21 passing through point P, and in region I it moves along a trajectory parallel to curve 20.
Since the trajectory moves parallel to , the trajectory will be like 22, and the deviation between the ideal trajectory 23 and the trajectory 22 will cause an error, but in this case, the trajectory 22 will be the ideal trajectory 23, that is, on the far side from the actual subject distance. If it is determined that the object is in focus, the so-called post-bin state, and is out of focus during one distance measurement cycle, for example, if the moving speed of V is constant, it is necessary to bring RR closer to the ideal trajectory 23. , RR toward the subject, it is sufficient to increase the moving speed.

By the way, the representative speed in area II is the rear focus in this case, but depending on the setting of the representative speed, the movement start position of the RR, etc., the focus is not always on the rear, and the focus is on the front side of the actual subject distance. This also results in a so-called front-focus state, and in this case, by slowing down the moving speed of the RR, it is possible to bring the object closer to the in-focus state.

From this, if it is not determined whether the front focus or the rear focus is in focus when out of focus, it is not possible to appropriately correct the speed of the RR by increasing or decreasing it from the representative speed. In the speed control method shown in Fig. 7 above, 1
If it is determined that the focus is out of focus during the distance measurement cycle, for example, R
In the next distance measurement cycle, the moving speed of R is increased, and it is determined whether or not it is approaching the in-focus direction. If it is, RR is driven at that corrected speed, and if not, the moving speed is reduced. It uses a trial and error one-sided system that drives by speed.

However, determining whether it is an anterior pin or a posterior pin,
Try driving RR at an increased or decreased correction speed,
If it is good, you can drive at that speed and there is no time loss, but if it is not good, you will have to change the speed again, causing a time loss, and the zoom operation during that time will be done out of focus, and furthermore, the front focus and the back focus will be determined. A program for this is required, which increases the number of circuits and the like, leading to an increase in the size of the device.

The present invention provides the above-mentioned front focus, by moving the lens 6 in advance so that it is always in either the front focus or the rear focus state in each divided area as shown in FIG. This method omits the judgment of rear focus and eliminates the delay in correction for focusing. For example, as shown in Fig. 3,
The representative speed for each divided area is determined so that the front is always in focus when zooming from the telephoto side to the wide-angle side.

Further, FIG. 8 shows another method of area division.

In this figure, the horizontal axis is divided in consideration of the deviation from the linear approximation of the ideal trajectory, and therefore the length in the variator movement direction is longer in the wide area. When the lens position was controlled as described above using this figure, although the accuracy was lower than when using FIG. 6, the results were almost the same.

Furthermore, according to the inventor's study, the area division examples shown in FIGS. 6 and 8 can provide sufficient accuracy even when used in a standard zoom of 6x class. Generally, the amount of movement of a TNW variator is around 20 mm, so the variator encoder's 1
Even in the example shown in FIG. 6, the length of the zone may be around 1+nm.

Therefore, this embodiment has the advantage that the division accuracy of the variator encoder can be rough compared to the conventional example.

FIG. 2 shows a circuit diagram of a control circuit to be combined with FIG. 1.

This control circuit is the main switch (SW) 14 of the camera.
2, a reset signal from the power-on reset circuit 143 is input to the CPU 130, and a predetermined number of pulses are sent to the step motor drive pulse output section 137 to reset the RR from the initial reset position outside the actual usage range to address 0. step motor driver 13.
8, the step motor 112 is driven, and the address 0 is reset.

141 is a zoom operation detection unit, which is a zoom switch (T
, W) 141 is performed, the T operation signal or W
The operation signal is transmitted to the CPU 130, which drives the zoom motor 140 via the zoom motor driver 139, and at the same time drives the step motor 112 via the step motor driver 138. CPU 130
In this case, the operation of the zoom switch (T, W) 141 becomes a trigger, and the position of the variator lens 2 is detected using the brush 107 and the board 106 described above, and the variator lens position is detected via the zoom encoder reading circuit 134. Information is communicated to CPU 130. Also,
The step motor drive pulse count circuit 136 counts how many pulses the step motor 112 is at from the reset position at address 0, and transmits the absolute position information of the RR to the CPIJ 130. CPII 130
is the area data memory 1 which stores these two lens position information and the deso as shown in FIGS. 6 and 8, for example.
From the numerical comparison with 33, the area where the absolute position of ■ and RR in the optical axis direction exists is determined, and for example, in FIG.
The area representative speed determined for each area is read out from the speed data memory 131 that stores representative speed data indicated by symbols I, 11, . . . in the figure. In FIG. 3, this area representative speed always brings the front focus as shown by reference numeral 601 when the zoom operation direction is from the telephoto side to the wide-angle side with respect to the ideal trajectory 600 shown by the broken line in the figure corresponding to the subject distance. In addition, the correction speed is set as shown by reference numeral 602, and the correction direction of RR in this case is always in the infinite direction, in order to approach the ideal trajectory 600.
In other words, it is moved toward the image sensor 129 side.

Note that the representative speed and correction speed in each divided area are set to -fffl in both operating directions, regardless of the zoom operating direction, so that only the correction direction is set in the opposite direction.

In other words, when the operating direction is from the wide-angle side to the telephoto side, RR
On the contrary, it moves so that it is in the rear bin state, so the correction direction of RR always moves to the close side in order to get closer to the ideal trajectory 600, and the correction direction of RR is immediately changed from the zoom operation direction. This makes it possible to simplify programs, etc. Furthermore, it goes without saying that the representative speed of RR may be determined so that the front focus is achieved when changing from the wide-angle side to the telephoto side.

141 is a zoom switch (T,
W), the direction data is memorized depending on whether the zoom operation is from wide to tele or from tele to wide! 32, the rotational direction of the step motor 112 is read into the CPt 1130. The CPt 1130 determines the moving direction and speed of the step motor 112 for driving the lens group 4B based on the contents read from these data memories and the blur information read from the AF device 135, and also determines the moving direction and speed of the step motor 112 for driving the lens group 4B. The driving direction of the motor 140 for driving the variator lens is determined according to the operation result. Thereafter, the two motors output to the step motor drive pulse output circuit 137 and the zoom motor driver 139 so that they operate almost simultaneously.

FIG. 4 is a flowchart for explaining the operation procedure of the CPo 130 described above. Note that this flow is configured to complete one round in 1760 seconds, for example.

In step 101, a device, such as a video camera, equipped with a lens embodying the present invention is powered on. At this point, the aforementioned step motor 11 is
The second reset operation is performed.

After that, in step 102, it is determined whether the focus is in focus or out of focus based on the distance measurement result, and if the focus is out of focus, step A in step 114 is performed.
Continue in F mode until focusing, for example at the RR position, point P in FIG.

V-R in FIG. 5 so as to match the ideal trajectory 23
To correctly position an RR on a curve corresponding to a subject distance of an R curve.

Next, in step 103, zoom operation (zoom switch 1
41) has been performed. If a zoom operation is not being performed, the process proceeds to the normal AF mode in step 114, and if a zoom operation is being performed, it is checked in step 10B whether or not focus is achieved during zooming, and the focus is adjusted. If it is determined that the camera is in focus, the process proceeds to step 104, and if it is determined that the focus is out of focus, the process proceeds to step 112.
Proceed to.

In step 104, the lens group (RR lens) 4B, which also serves as the variator lens 2 and the lens group (RR lens)
Detect the position of.

Based on this result, in step 105, (v.

Detect the region to which the point RR) belongs, and step 10B
Then, corresponding to this area, set the front pin from the speed data memory and read out the area representative speed, and use this result as v
Let it be n. Note that this area representative speed may be stored as an extraction input pulse interval of a dimension such as mm/sec, and in step 107, the zoom operation direction is changed from the telephoto side to the wide-angle side or from the wide-angle side to the telephoto side. In steps 109 and 110, the RR lens drive speed 5=vn and zoom operation direction D-Dn are set, and in step 110, the lens is driven at the set speed S and in the set direction.

On the other hand, if it is determined that the focus is out of focus in step 108 during this zoom operation, the driving speed S of the RR is switched from the representative speed vn to the correction speed ve in step 112, and the moving direction of the RR is changed in the correction direction in step 113. Switch to DC and drive.

In this case, the correction direction Dc is determined according to which division, as shown by reference numeral 602 in FIG. In the area, - is also set on the infinity direction side, that is, on the side of the image sensor 129 in FIG.
It approaches the ideal trajectory 600 at a corrected speed vc and focuses on it.

Also correction speed ■. It is preferable to make it as large as possible in consideration of the mechanical load on the lens system, etc., in order to reduce time loss until focusing.

Then, when the representative speed and moving direction are switched and the focus is focused, the zoom operation is performed again from step 108 to step 104 and thereafter, and when the focus is out of focus, the above-mentioned R
By correcting the speed and moving direction of R, and tracing the ideal trajectory 600 while repeating this operation, it is possible to obtain a zoom operation without blurring, and the blanking point used to determine whether the focus is in focus or out of focus in step 108 can be obtained. If the discrimination conditions such as values are made stricter, the jagged steps of the step-like curve shown in FIG. 3 will become smaller, and the step-like curve will be made smoother, allowing zoom operations to be performed while maintaining highly accurate focusing.

On the other hand, when the zoom operation is from the wide-angle side to the telephoto side, the RR
In the case of the zoom operation from the telephoto side to the wide-angle side, as described above, except that the camera moves so that the rear focus is on the contrary, and the RR correction direction when it is determined to be out of focus is directed toward the subject. The drive control of the RR is performed in the same manner.

In other words, in this embodiment, the movement of the RR is set in advance so that the front focus is focused when zooming from the telephoto side to the wide-angle side, and the rear focus is focused when zooming from the wide-angle side to the telephoto side. In some cases, it is possible to immediately focus by simply moving the RR in the correction direction determined in advance according to the zoom operation direction, without the need for processing to find the correction direction of the RR. The processing time can be shortened, and the photographer can perform zoom operations without noticing the occurrence of blur.

Embodiment 2 FIG. 16 is a flowchart showing Embodiment 2 of the present invention.

In this embodiment, in the V-RR characteristic curve shown in FIG. 20, a point B indicating approximately the apex of an ideal trajectory 900 corresponding to the subject distance is determined, and the position of V is The correction of RR when out of focus is changed depending on whether the camera is on the wide-angle side or the telephoto side. Steps 701 and 702 are added to the first embodiment described above, and in step 701, ■ position is B
It is determined whether the point is on the wide-angle side or the telephoto side, and if it is on the wide-angle side, steps 112 and 113 are executed in the same manner as in Example 1 above, and RR is adjusted at the correction speed vc. It is driven in a predetermined direction DC, and if it is on the telephoto side, the movement of the RR is stopped in step 702.

In Fig. 20, when moving the zoom from the telephoto side to the wide-angle side, the RR is in the front bin state as shown by the numbers 901.905, and when moving the zoom from the wide-angle side to the telephoto side, the RR is in the front bin state.
moves in a backward pinned state as shown by symbols 907 and 903. Here, when zooming from the telephoto side to the wide-angle side, if ■ is located on the telephoto side than point B and it is determined that the focus is out of focus, since RR is in the front bin state, If the movement of , RR is stopped (the correction speed indicated by the symbol 90.2 is set to $), then ■ will move toward the wide-angle side and approach the in-focus side. Similarly, when zooming from the wide-angle side to the telephoto side, if ■ is located closer to the telephoto side than point B and it is determined that the focus is out of focus, RR
Since the lens is in the rear focus state, if the g movement of RR is stopped (the correction speed indicated by reference numeral 903 is zero), the lens (2) moves toward the telephoto side and approaches the in-focus side.

On the other hand, on the wide-angle side from point B, the correction speed is 908.9
When 08 is stopped, 2 moves in a direction away from the in-focus direction, so in this case, the same correction process as in the first embodiment described above is performed.

In this embodiment, when moving from the telephoto side to the wide-angle side, RR is set to focus on the front, but it may be set to focus on the rear, and in this case, the determination in step 701 becomes V>B. Conversely, the RR correction speed on the wide-angle side of point B is set to zero, and the correction process on the telephoto side is performed in the same manner as in the first embodiment.

That is, in the first embodiment, the correction is made by moving the RR in the direction opposite to the movement direction for zooming in the area on the telephoto side of point B, but according to this embodiment, the correction is performed on the telephoto side of point B. By setting all speeds to zero,
Not only does the operation become smoother because correction speed control that involves small direction changes can be omitted, but also the load on the drive motor and drive mechanism can be reduced.

Embodiment 3 In this embodiment, the correction speed Vnc of RR in each divided region is
and correction direction Dnc in advance, and step 801. In step 802, these correction speed Vnc and correction direction Dnc are read, and if it is determined that the focus is out of focus,
The RR is driven and controlled using the read correction speed Vnc and correction direction Dnc.

That is, in this embodiment, since the correction speed and correction direction are set for each divided area, optimal correction processing can be performed and smooth focusing correction can be performed.

In each of the embodiments described above, the lens type shown in FIG. 14 has been described, but the lens type shown in FIG. 17 can also be used.

[Effects of the Invention] According to the present invention, by setting the representative speed of the second lens group that serves both correction and focusing to be out of focus, for example, front focus or back focus, the correction direction can be adjusted. It can be determined in a simple manner, and the time required to determine the correction direction can be omitted, making it possible to speed up the response time until focusing. Moreover, it is possible to simplify the program, and it is possible to eliminate the time required to determine the correction direction. It can contribute to miniaturization of electronic control circuits.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a zoom lens according to a first embodiment of the lens position control device in an optical instrument according to the present invention, and FIG.
FIG. 3 is a circuit diagram of a control device that drives and controls the zoom lens shown in FIG. 3. FIG. 3 is a diagram showing the usage area of the two movable lenses of the zoom lens shown in FIG. Optical equipment for implementing the device (Figs. 1 and 2)
Flowchart of the program implemented in Figure),
FIG. 5 is a map used to display the relative positional relationship of two movable lenses for each subject distance in a zoom lens as an optical device in which the present invention is implemented, and to explain the present invention in detail; FIG. is a diagram in which FIG. 5 is divided according to the principle of the present invention, FIG. 7 is a diagram illustrating the principle of the conventional control system by enlarging a part of FIG. 6, and FIG. 8 is a diagram similar to FIG. 5 is divided by another division method according to the principle of the invention, FIG. 9 is a diagram showing the lens configuration of a conventional conventional zoom lens to which the present invention cannot be applied, and FIG. 10 (a
) and (b) are diagrams showing the movement characteristics of the variator lens and the movement characteristics of the convencator lens in the conventional zoom lens, and FIGS. 11 and 12 are diagrams showing the movement characteristics of the variator lens in the conventional zoom lens shown in FIG. Figure 13 is a diagram showing the relationship between the position of the first lens group and the subject distance. Fig. J9 shows a mechanical control mechanism adopted for interlocking the variator lens and convencator lens in the zoom lens, and Fig. 14 shows the lens configuration of the zoom lens to which the present invention is applied. The figure shown in Fig. 15 is a diagram showing the relative positional relationship between the variator lens (V) and the relay rear lens (RR) for each subject distance in the zoom lens shown in Fig. 14, and Fig. 16 (A). is the first
A schematic diagram showing a known control method for controlling the zoom lens shown in FIG. 4, FIGS. 16(B) to (D) are illustrations of an example of the AP principle, and FIG. A diagram showing the configuration, FIG. 18 is a flowchart of the second embodiment,
FIG. 19 is a flowchart of the third embodiment, and FIG. 20 is a diagram showing a method of driving the relay rear lens (RR) of the second embodiment. 1... 1st group lens 2... 2nd group lens 3...
・Third group lens 4...Fourth group lens 4A...Relay front lens 4B...Relay rear lens Figure 16 (A) 16 [ff1 (B) !1611k (C) Figure 17 Figure 18 Figure 19

Claims (1)

[Scope of Claims] 1. A first lens group that moves along the optical axis to perform a zooming action, a second lens group that performs correction and focusing actions during zooming; Lens group position detection means for detecting the position of the first lens group and the position of the second lens group, respectively, and focusing the position, speed, etc. of the first and second lens groups upon detection of a magnification change operation. drive control means for controlling based on focus/out-of-focus determination from the detection means, the drive control means controlling position information of the first and second lens groups and movement of the first lens group; A second lens that stores representative speed information of a plurality of second lens groups that are set to be out of focus in a specific direction according to the speed information, and also stores correction information that corrects the representative speed. a group movement information storage unit, driving the second lens group substantially simultaneously with the first lens group, and driving the second lens group until the second lens group is brought into focus according to correction information when out-of-focus is detected; 1. A lens position control device for an optical instrument, comprising: a second lens group drive control means for controlling the lens group and then controlling the drive until out-of-focus is detected based on representative speed information. 2. The representative speed correction information stored in the second lens group movement information storage section of the drive control means is speed information and a moving direction approaching an ideal trajectory determined for the subject distance. A lens position control device for an optical device according to claim 1. 3. The representative speed correction information stored in the second lens group movement information storage section of the drive control means is a region in which the moving direction of the first lens group approaches an ideal trajectory determined for the subject distance. 3. The lens position control device for an optical instrument according to claim 1, wherein a speed of zero is set in the lens position control device for an optical instrument.