JPH01280709A - Lens position controller for optical apparatus - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a large out-of-focus to be caused by a delay in a range finding cycle, etc., by moving the 2nd lens group almost simultaneously with the 1st lens group by selecting information from plural pieces of information previously obtained based on the positional information of the 2nd lens group and moving speed information of the 1st lens group. CONSTITUTION:The 1st lens group 1 is fixed and a variator lens 2 is moved when a bar 108 is turned by means of a zoom motor. A lens group 4A is fixed and a lens (PR) 4B is moved when a bar 114 is rotated. When zoom switches (T and W) are operated, a CPU selects specific information from plural pieces of lens 4B movement controlling information stored in a control means from a speed data memory and decides the moving direction and speed of the lens 4B and, at the same time, the moving direction of the lens 2 from the lens position information of the lenses 2 and 4B and the selected movement controlling information. Then the CPU causes the two lenses 2 and 4B to move almost simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for controlling the position of a lens in an optical device such as a camera or an observation device.

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

In Figure 7, 1 is the 1st group lens F located at the tip of the lens barrel for focusing, 2 is the 2nd group lens ■ which is a variator lens for changing the magnification, and 3 is the focal point after the magnification changing operation. The third lens C14, which is a convencator lens for properly converging the images, is the fourth group lens R1, which is a relay lens for forming an image. In addition, Fig. 7 is a diagram in which the focal length of the zoom lens is at the wide end (shortest), and the object is in focus at (1) distance.The following describes how each lens group moves. Therefore, in this state, 1
The positions of group lens F, second group lens V, and third group lens C are each considered to be the zero position.

8 to 10 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.

In FIG. 8(a), the horizontal axis is the position where the second group lens ■ has been moved along the optical axis, and the focal pressure of the zoom lens is lll1.
It is a graph showing how the focal length f changes when the second group lens V is moved with If as the vertical axis. 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. 8(b), the position of the third group lens C in the optical axis direction is plotted on the horizontal axis, and the focal pressure mf of the zoom lens is plotted on the vertical axis.
Focal pressure 11+II f with respect to change in position of group lens C
This is a graph showing changes in .

In Figure 9, the horizontal axis represents the reciprocal of the distance (meters) to the subject, and the vertical axis represents the position of the first lens group F when it is moved forward along the optical axis direction. FIG. 3 is a diagram showing changes in subject distance with respect to changes in position.

Figure 10 shows the position and focal length of the first lens group, with the vertical axis representing the position when the first lens group F is moved forward along the optical axis direction, and the focal length f of the zoom lens taking the horizontal axis. In addition to showing the relationship with f, the distance to the subject is 1m, 2m, 3m.
It is a graph illustrating the position of the 1st lens group F for each case of m and oO.

From the above figures, it can be seen that known zoom lenses have the following characteristics. In other words, as is clear from FIGS. 9 and 10, if the subject distance does not change, even when zooming and changing the focal length, the first
Since there is no need to move the group lens F, the second group lens V
The advantage is that it is relatively easy to control the position of each lens because it is only necessary to interlock the and third group lens C according to the characteristics shown in FIG. 8, and that the position control can be performed using a mechanical control mechanism such as a cam. There is.

Figure 11 shows the second group lens 2 (variator lens) and third group lens 3 (compensator 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 provided with a bottle 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 8 and 6a are inserted; a fixed cylinder 10 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 as to be able to rotate only relative to the outer peripheral surface of the fixed cylinder 10. Zoom operation when zooming:
IJ! 11 is rotated, the cam cylinder 9 is also rotated, and as a result, the relative position of the bottle 5a within the cam groove 9a and the cam groove 9b are changed.
Since the relative position of the bin 6a inside changes, the second group lens holding frame 5 and the third group lens holding frame 6 are each relatively moved along the optical axis direction.

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

Moreover, as is clear from FIGS. 9 and 10, with conventional zoom lenses, the close-up pressure is 1111t (for example, 1m
In order to focus on the subject shown below), the amount of extension of the first lens group 1 must be increased in proportion to the reciprocal of the distance, and in order to focus just in front of the lens, it must be extended an almost infinite amount. This had a serious drawback in that it was impossible to take pictures at close range.

Therefore, recently, a so-called inner focus type zoom lens has been proposed, which allows focusing without moving the first lens group 1. An example of this zoom lens has a first group lens 1 and a second group lens 2 as shown in FIG. 12, but does not have a third group lens corresponding to a conventional convencator. In this zoom lens, the first group lens 1 and the front lens 4A(R) of the fourth group lens are configured as non-moving lenses, while the variator of the second group lens 2 is used as a focal point like the known zoom lens shown in FIG. It is configured to be moved when the distance changes. Furthermore, the rear lens 4B (RR) of the relay lens group 4 has the function of performing focus adjustment and correction in the same way as the convencator lens of a conventional zoom lens. Focus adjustment and correction are performed by moving the lens along the optical axis.

Further, as another example of the structure of the inner focus type zoom lens, there is an example as shown in FIG. 15. 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. 7 is that the first group 1 is attached and fixed to a fixed mirror 1Ilii 1101. For this reason, the third group lens 3, which conventionally only had a correction function, now also has a focusing function.

In a zoom lens with such a lens configuration, the first lens group 1 does not move, so it is possible to focus on objects at extremely close distances. Relay rear lens 4
Since the relative positional relationship with the third group lens 3 in the case of B or 15 is extremely complicated, a simple control mechanism such as a cam mechanism as shown in FIG. Therefore, it is extremely difficult to put into practical use a zoom lens having the lens configuration shown in FIG. 12 or 15 using only a mechanical mechanism. Ta.

In Figure 13, the horizontal axis represents the position of the second group lens (V) in the zoom lens shown in Figure 12, 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).As is clear from Figure 13, the relative positional relationship between both lenses is as follows when the subject distance is m, 1 m, 0.5m, 0.2
It is understood that it is impossible to control both lenses by a simple control mechanism such as a cam, because the distance changes as the distance changes, such as m and 0.01 m.

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. 14(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 a rear lens of the relay lens, 12 is an imaging detection means in the focal plane, 13 is a focus control (AF) circuit for focus detection and focus control, and 14 is a rear lens controlled by the AF circuit 13. This is a driving means for positioning and driving the lens 4B.

FIG. 14(B) to FIG. 14(D) show an example of an automatic focus adjustment device. In FIG. 14 CB), 17 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 actually possessed by the subject. In FIG. 14(C), if (a) is this contrast part, then
(b) is the Y signal output, (C) is the differential value of the Y signal, (d) is its absolute value, and (e) is the signal after peak hold. Indicates the degree of focus. In Fig. 14 (D), the vertical axis is the lens position 1 in Fig. 7 or 4B in Fig. 12, and the vertical axis is A.
However, focusing is achieved at peak position B.

In addition, as another improved method, Japanese Patent Application Laid-Open No. 62-2961
No. 1Q, Japanese Unexamined Patent Publication No. 62-411431ti, etc. have been proposed. This is based on the positional information of the variator lens and a lens that also serves as a convencator and focus function, or the positional information of the variator lens and a distance operation member (distance ring). The unit movement amount of a lens that serves multiple functions (hereinafter referred to as a dual-purpose lens) is stored in memory, and the movement of the dual-purpose lens is controlled based on the memorized unit movement amount every time the variator lens moves by a predetermined amount. This is what I did.

[Problem to be solved by the invention] In the known zoom lens and lens position control method shown in FIG. Is there a possibility that blur or distortion will occur in the image that appears on the surface?In fact, there is a very high possibility that the control accuracy of the relay rear lens 4B will decrease due to response delays such as distance measurement cycles, so please avoid large blurs. It had a major drawback: it was raw.

In addition, in the above-mentioned improved method, it is necessary to detect a predetermined amount of 8 movements of the variator lens, so in order to obtain highly accurate movement of the dual-purpose lens, the amount of movement of the variator lens must be made extremely small. Furthermore, there are concerns that the moving speed of the lens that also serves as a lens must not be made high enough, and that it will 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 and effects for solving the problems] The lens position control device of the present invention includes a first lens group that moves for zooming, and a second lens group that moves for correction and focus adjustment. The feature of the device of the present invention is that when an operation to change the position of the first lens group is detected, the device changes the position of the first lens group. While detecting the position of the second lens group, a plurality of oscillation controls are prepared in advance corresponding to the position information of the first and second lens groups and the moving speed information of the first lens group. 2 Select specific movement control information that corresponds to the position detection results of both lens groups from among the specified information, and use the selected movement control information to control the movement of the second lens group to be approximately the same as that of the first lens group. The idea is to have them done at the same time.

[Example] Examples of the device of the present invention will be described below with reference to FIGS. 1 to 5, but first, the basic principle of the device of the present invention will be explained with reference to FIGS. 2 and 3. Explain the idea.

Figure 2 shows the second group lens 2 (
(described as ■ below) and relay rear lens 4B
This is a map showing the relative relationship with the position of RR (hereinafter referred to as RR) for each subject distance.◇ In Figure 2, the point 21 is where the position of RR and the position of Assume that the distance measurement cycle in the focusing control means that controls this zoom lens is tl. If it is assumed that the distance measurement cycle is started at the same time as the movement of ■, the positional relationship between ■ and RR will change to point P2 until the next distance measurement result is obtained.

On the other hand, if RR is moved simultaneously with the movement of ■, the relative positional relationship between V and RR will be the value represented by point P3, even if no correction is made by distance measurement, and as a result,
The deviation from the ideal point P4 is d2. For example, if the effect amount of ■ on the focal plane at the focal lengths of P1 to P4 is expressed as lO, and if the F number at this time is F, the diameter of the generated circle of confusion is zero at point P4, and at point P3. d2/F,
Point P2 becomes d, /F. Here, assuming that d,=5d2, 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 P1, correctly predict the cam passing through point P1, and then calculate the necessary moving speed of RR, which requires large-scale calculations. As a result, a problem arises in that a large-scale arithmetic circuit is required, which increases the cost of the focusing control means.

Therefore, in the present invention, the map shown in FIG. 2 is divided in both the ■ direction and the RR force direction according to the required accuracy,
A method was adopted in which the representative speeds for each area were memorized in the memory of the electronic circuit.

FIG. 3 shows an example in which the map in FIG. 2 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 beauty and the closest trajectory passing within one area in the RR force direction ■ divided by the target depth of field. .

FIG. 4 is a diagram for explaining the case where the moving speed of RR, etc. is determined from the relative position curve between ■ and RR within the regions of I and II in FIG. In FIG. 4, 23 is a relative position curve that passes through point P5 and the subject distance is constant, and curves 20 and 21 are slopes of lens movement that are stored in electronic circuits, etc., corresponding to each area. be.

(Note that when the moving speed of the variator is constant, RR
It can be thought of as the moving speed of ) When moving from point P5 without feedback from AF, the trajectory passes through point P5 and is parallel to curve 21 while in region I+, and moves parallel to curve 20 in region I, so the trajectory is as shown in 22. Become. The difference between the ideal trajectory 23 and the trajectory 22 is an error.

FIG. 5 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 locus, and therefore, in the wide area, the length in the variator movement direction is longer. When the lens position was controlled as described above using this diagram, although the accuracy was lower than when using FIG. 3, the results were almost the same.

Further, the area division examples shown in FIGS. 3 and 5 can be used with sufficient precision even if they are adopted in a standard 6-B class zoom according to the inventor's study. Generally, the amount of movement of the variator for T % W is around 20 mm, so 1 of the variator encoder
In the example shown in FIG. 3, the length of the zone may be around 1 mm.

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

In FIG. 6(A), 1, 2.4A, and 4B are the lens groups already explained in FIG. 12. 1 group lens 1
is fixed to the lens frame 103, screwed together with the fixed lens barrel 102 so that the lens position is optimally positioned, and then fixed with screws 104 after adjustment. The variator 2 is fixed in a variator moving gap 105 and moves in the thrust direction (optical axis direction) using a 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 pole (not shown) is pressed into this groove by a plate spring (not shown) fixed to the variator ring. The position is determined by this, and the zoom motor 140 shown in FIG.
By rotating the bar 108, its position can be changed. Further, a brush 107 is attached to this movable ring, which constitutes a variator encoder by sliding between it and the encoder board 106. 109 is an iG claw which controls the aperture diameter by driving the blades 111. The lens group 4A is fixed to the lens barrel 108. Further, the lens (RR) 4B is attached to a moving ring 117, and the lens 117 is integrated with a sleeve 115 which is internally threaded. bar 1
14 is machined with a male thread, and as a result, the lens group 4B changes its position by rotation of this bar 114. This bar 114
For rotational operation, a step motor 112 is provided which is interlocked with a pulley 113 and a belt 120.

In this example, step motor 1 is used to detect the position of lens group 4B, which has both convencator and focus functions.
A number of input pulses of 12 can be used. However,
When the power is turned on or off, it is necessary to bring the lens group 4B to a certain predetermined address 0. In the figure, moving ring 1
The 122nd part of the 17 is configured to be the 0 address, which is the position where the 0 address adjustment cam 121 hits.

FIG. 6(11) shows a circuit diagram to be combined with FIG. 6(8). When the main 5w 142 is turned on, the power-on reset circuit 143 activates the step motor 11 as described above.
Address 2 of 0 is reset.

141 is a zoom operation detection unit, which is a zoom switch (T
, w) is transmitted to the CPU 130. The operation of the zoom switch (T, w) becomes a trigger in the CPU 130, and the position of the variator lens 2 is determined by the zoom encoder reading circuit 134 using the brush 107 and the board 10 [i].
130. Also, the step motor 112 is 0.
The number of pulses from the reset position is counted by the step motor drive pulse count circuit, and the C
transmitted to PU 130. The area is determined by comparing the numerical values between these two pieces of position information and the area data memory 133, and the area representative speed is read out from the speed data memory 131.

Furthermore, the zoom switch (T, w) of the zoom operation detection unit 141
) is read from the direction data memory 132 into the CPII 130 depending on whether the operation is from wide to telephoto or from tele to wide. The CPII 130 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. 1 is a flowchart 1 for explaining the flow of the CPIJ 130 of the present invention explained in FIGS. 6(8) and 6(B). For example, this flow is 1/60
It is configured to rotate once every sec.

In step 201, a device, such as a video camera, equipped with a lens embodying the present invention is powered on. At this point, according to a flow (not shown), the step motor 11
The second reset operation is performed.

Thereafter, in step 202, it is determined whether the AF device is on or off, and if it is off, the correction function does not work, so zooming is prohibited (step 203). Next step 20
At step 4, it is determined whether a zoom operation (141 in FIG. 103) has been performed.

If zoom operation is not performed +-+, step 20
The process advances to the normal distance measurement routine 205 in step 5.

When a zoom operation is being performed, in step 206, the previous AF device blur evaluation result A0 (contents of register A) is stored in register A2. A at the start of zoom. For example, if it is not available, use A2-0. In step 207, the current blur evaluation value A is stored in register A1. In step 208, the values of A and -A2 are stored in the register Ad. In step 209, the current blur evaluation value A is stored in register A. Store in. In step 210, pulses from the zoom encoder and step motor are used to control the variator lens 2 and the lens group (
RR lens) 4B position is detected. Based on this result, in step 211, the area to which the point (V, RR) belongs in the map is detected from the area data memory, and in step 212, the area representative speed is determined from the speed data memory corresponding to this area. read out. ■This result. (
The speed may be stored as an external pulse interval in dimensions such as mm/sec. ) In step 213, it is determined whether it is time to start zooming. At the start, in step 215, the driving speed of the motor 112 is set to v=v (also, the driving speed of the motor 14 for the variator is
(speed 0 is a predetermined constant speed) Driving of the variator lens 2 and the lens group 4B is started at the same time.

These two lenses cannot be moved unless the zoom operation is completed or variator lens 2 reaches the end of the movement range.
This will continue from now on.

From the second round onward in this flow, step 214 is performed. In step 214, the blur evaluation value A is the allowable blur level Th.
It is determined whether the value exceeds 1. A>T11.
Since the blur is within the allowable range, step 219
Therefore, V=V is set.

Also, when the blur is A < T h +, step 2
At step 16, the sign of A is determined. Since A d>O indicates that the degree of blur has been reduced between the last time and the current 1760 seconds, the increase flag is not changed, and the same determination as the last time is made in step 218. , ■ or step 220 or 22 as before
Set to 1. The speed ■ when the blur is less than Th is expressed as v=k・■o, and k in step 220 is k 2
If k of 20221 is 22, then k22o and 22
1 is k 220 < 1 < k 221 or 22
The relationship +<1<k22o is good. (In Fig. 1, it is assumed that 22o = 1.1 and k22+ = 09.

) Between the previous time and this time, if the blur is blurred or enlarged, the increase flag is inverted in step 217, and the increase flag is inverted in step 217.
At step 18, a selection different from the previous one is made.

In the above embodiments, the lens type shown in FIG. 12 has been described, but the lens type shown in FIG. 15 can also be used.

[Effects of the Invention] According to the present invention, it is possible to greatly improve the blurring that occurs due to a delay in response of the output of the focus detection means, etc., and therefore, it is possible to provide a highly accurate optical device. I can do it. In particular, since the lens that performs correction and focusing can be moved almost simultaneously with the movement of the lens that affects magnification, it is possible to reduce the occurrence of blur and increase the speed of magnification.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of a program executed in an optical device (FIG. 6) for implementing the device of the present invention, and FIG. 2 is a diagram showing the relative relationship between two movable lenses in a zoom lens as an optical device in which the present invention is implemented. A map used to display the positional relationship of objects for each object distance and to explain the present invention in detail. FIG. 3 is a diagram obtained by dividing FIG. 2 according to the principle of the present invention, and FIG. 5 is a diagram illustrating a detailed explanation of the present invention with an enlarged portion; FIG. 5 is a diagram obtained by dividing FIG.
FIG. 6 (8) is a diagram showing an example of a zoom lens as an optical device for carrying out the present invention, and FIG.
Figure (8) is a circuit diagram; Figure 7 is a diagram showing the lens configuration of a conventional conventional zoom lens to which the present invention cannot be applied;
Figures (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 Figures 9 and 10 are diagrams showing the movement characteristics of the variator lens and the convencator lens in the conventional zoom lens, and Figures 9 and 10 are diagrams showing the movement characteristics of the conventional zoom lens in Figure 7. Figure 11 is a diagram showing the relationship between the position of the first group lens in the lens and the object distance. Figure 11 shows the mechanical control adopted to link the variator lens and compensator lens in the zoom lens of Figure 7. FIG. 12 is a diagram showing the lens configuration of a zoom lens to which the present invention is applied, and FIG. 13 is a diagram showing the variator lens (V) and relay rear lens ( Figure 14 (A) is a diagram showing the relative positional relationship with RR) for each subject distance.
A schematic diagram showing a known control method for controlling the zoom lens shown in Figure 2, Figures 14 (B) to (D) are explanatory diagrams of the AF principle, and Figure 15 shows the lens configuration of another zoom lens. FIG. 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 14 (C)

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; In a lens position control device for an optical instrument, which is equipped with a control means for controlling the position, moving speed, etc. of the first and second lens groups, when an operation for changing the position of the first lens group is detected, the first lens group A detection means is provided for detecting the position of the lens group and the position of the second lens group. select specific movement control information from among the movement control information of the plurality of second lens groups stored in the control means, and control the movement of the second lens group using the selected movement control information. It is characterized by being provided with a control means for causing the movement to be performed almost simultaneously with the moving speed of the group lens,
Lens position control device in optical equipment. 2. The lens position control device according to claim 1, wherein the moving speed of the first lens group is constant when the position of the first lens group is changing. 3. Claim characterized in that when the optical system is in an out-of-focus state, the second lens group is moved at a speed equal to the speed to be applied to the second lens group multiplied by a coefficient of k≠1. 1
Or the lens position control device according to 2.