JPH09288232A - Control method for zoom lens camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a focusing operation, and simultaneously to perform a lens driving operation with giving consideration to the adjustment only by measuring and inputting the positional deviation with reference to the focusing plane at a wide end and a telephoto end without performing a mechanical zooming adjustment and an fB(back focus) adjustment. SOLUTION: First, the focusing plane positions at the wide end and the telephoto end are measured so as to obtain the deviation amount in the optical axis direction. Next, in order to make the positions of the focusing plane coincide, the moving amount required for a front group lens L1 is obtained, and then, the driving pulse number for each motor required to impart the moving amount is obtained. Thereafter, each moving amount of the front group lens L1 and a rear group lens L2 necessary to make the focusing plane position coincide with the focal plane of the camera is obtained, then, the driving pulse number for each motor required to impart the moving amount is obtained. Next, with giving consideration to the pulse number obtained in such a way and the pulse number based on focal distance information and object distance information, each motor is controlled through a pulse encoder at a focusing operation time.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of controlling a zoom lens camera, and more particularly to a method of controlling a zoom lens in consideration of zooming adjustment and back adjustment.

[0002]

2. Description of the Related Art Zoom lenses are indispensable for zooming adjustment so that the focus plane position does not move during zooming and fB (back focus) adjustment for making the focus plane position coincide with the focal plane of the camera. is there.
The zooming adjustment is usually performed as an adjustment for matching the focus surface positions at the telephoto end and the wide-angle end. This adjustment has conventionally been performed by mechanically changing the lens position.

[0003]

SUMMARY OF THE INVENTION The present invention is a mechanical zooming adjustment and f
An object is to obtain a control method for a zoom lens camera that does not require B adjustment.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a lens system having a movable front lens group and a rear lens group; a motor for moving the front lens group and the rear lens group integrally; a rear lens group with respect to the front lens group. It is premised on using a zoom lens camera provided with a rear group motor for moving the lens; and a pulse encoder for controlling the rotational position of each motor. According to the present invention, such a zoom lens camera does not require mechanical zooming adjustment and fB adjustment, but simply measures the amount of deviation of the focus surface position between the wide end and the tele end, and performs pulse calculation necessary for driving the motor. If the motor is controlled by performing the above, the zoom lens can be controlled in consideration of zooming adjustment and fB adjustment.

The present invention relates to a lens system having a movable front lens group and a rear lens group; a motor for moving the front lens group and the rear lens group integrally; and a rear lens group for the front lens group. In a zoom lens camera equipped with a rear group motor to be moved; and a pulse encoder for controlling the rotational position of each motor, a focus plane position at a wide end and a tele end is measured to obtain a shift amount in the optical axis direction. Step 1; The amount of movement required for the front lens group is obtained in order to match the focus surface positions at the wide end and the tele end without moving the rear lens unit, and the rear lens unit is moved without moving the rear lens unit. The second step of obtaining the number of drive pulses of each motor required to give the moving amount to the lens; the focus plane position resulting from giving the moving amount to the front lens group is set to the focal plane of the camera. A third step of obtaining the amount of movement of the front lens group and the rear lens group necessary for the movement, and the number of drive pulses of each motor required to give the movement amount to the front lens group and the rear lens group; In consideration of the number of pulses obtained in step 3, the number of pulses obtained in the third step, the number of pulses based on the focal length information, and the number of pulses based on the subject distance information, each of the pulse encoders is used for focusing operation. And a step of controlling the motor.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the principle of a control method for a zoom lens camera according to the present invention. Now
A lens system having a movable front lens group L1 and a rear lens group L2; a motor for moving the front lens group and the rear lens group integrally; a rear lens group for moving the rear lens group with respect to the front lens group In a zoom lens camera equipped with a motor; and a pulse encoder for controlling the rotational position of each motor, a rear lens group lens L2 is driven by a rear lens group motor while a front lens group L1 and a rear lens group L2 are moved forward by a motor for overall movement. Consider a virtual front group focusing method in which the lens group is moved backward by the same amount (that is, without moving the rear lens group L2) and focusing is performed. In the state before zooming adjustment, it is assumed that, in the virtual front group focusing method, the amount of deviation between the focus surface positions of the wide end and the tele end with respect to the subject at the same distance is y. This shift amount is set to Z as indicated by the broken line of the front lens group L1 without moving the rear lens group L2.
Zooming adjustment is to _remove only _adj .
Regarding the position of the rear lens group L2, the position moved forward by Z _{adj by the} motor for overall movement is shown by a broken line, and the position moved backward by the same amount by the motor for rear group is shown by a solid line. In zooming adjustment, the focus surface positions at the wide end and the tele end match, but the focus surface position after this zooming adjustment does not match the focal plane (rail surface) position F of the camera. When the amount of movement of the focal plane position at the wide end after this zooming adjustment is x and the amount of movement required to match this focal plane position with the focal plane F is fB _adj , the following equation is established. x = y · [1 / {(K ₁ T / K ₁ W) −1}] Z _adj = x / K ₁ W X _1adj = fB _adj −Z _adj where K ₁ W: front lens group at wide end , K ₁ T: the focus sensitivity of the front lens group at the telephoto end, X _1adj : the difference between fB _adj and Z _adj of the front lens group L 1.

As is clear from the above analysis, y is obtained by measuring the focus plane positions A and B with respect to the focal plane (rail plane) position F, and the C position is obtained by calculation x. If the C position is known, fB _adj can be obtained. The zoom lens camera to which the present invention is directed controls the positions of the front lens group and the rear lens group in the optical axis direction by the two motors and the pulse encoder that controls the rotational position of each motor. , Z _adj obtained based on the measurement result of y, fB _adj, the X _1Adj terms of number of pulses, which number of pulses based on the focal length information, and adds the number of pulses based on the subject distance information, focus If the position of each lens group is controlled during operation, mechanical zooming adjustment and fB adjustment are unnecessary.

The present invention will be described below with reference to specific examples. The applicant of the present invention has proposed, as a new zoom lens camera, a lens system having at least a movable front group lens located on the object side and a movable rear group lens located on the image plane side;
Overall movement motor that moves the front lens group and the rear lens group as a unit; Relative movement motor that relatively moves the rear lens group and the front lens group to change the distance between the front lens group and the rear lens group; Focus by lens system Zoom operating means for setting the distance; and focus operating means for starting the focusing operation;
We proposed a zoom lens camera with
72216). In this zoom lens camera, when the focus operating means is operated in at least a part of the focal length range set by the zoom operating means, both the overall movement motor and the relative movement motor are operated to focus on the subject.

2 and 3 show an embodiment of this zoom lens camera. The zoom lens is a positive front lens group L1.
And a negative rear lens group L2. A drive ring 12 is rotatably supported on the outer circumference of the fixed ring 11 of the lens barrel, and a front group support ring 13 that supports the front group lens L1 and a rear group support that supports the rear group lens L2 on the inner circumference. Ring 14
Is fitted. A straight guide groove 11a parallel to the optical axis is formed in the fixed ring 11, and the radial pin 15 fixed to the front group support ring 13 penetrates the straight guide groove 11a to reach the inner surface of the drive ring 12. Formed lead groove 12a
It is stuck in. A gear 17 is provided on the outer circumference of the drive ring 12.
Is fixed, and this gear 17 is
It meshes with the gear 19 of the.

The fixed ring 11 is formed with another rectilinear guide groove 11b for the rear group, and the radial pin 20 fixed to the rear group support ring 14 is fitted in the rectilinear guide groove 11b. The front group support ring 13 includes a rear group movement motor 21.
And a drive screw shaft 22 rotatably driven thereby, and the drive screw shaft 22 is engaged with a non-rotating nut member 23 provided on the front group support ring 13.

According to the above-mentioned mechanical structure, when the drive ring 12 is rotationally driven via the overall movement motor 18, the front group support ring 13 (front group lens L1) is driven by the light in accordance with the relationship between the lead groove 12a and the straight guide groove 11a. Move in the axial direction.
The rear group support ring 14 (rear group lens L2) is mounted on the front group support ring 13 in accordance with the driving screw shaft 22 and the nut member 23 of the rear group movement motor 21, and therefore moves integrally with the front group support ring 13. To do. That is, the overall movement motor 18 is a motor that moves the entire lens group. On the other hand, when the drive screw shaft 22 is rotationally driven via the rear group movement motor 21, the rear group support ring 14 (rear group lens L2) moves relatively to the front group support ring 13 (front group lens L1). . That is, the rear lens group moving motor 21 is a motor that changes the distance between the rear lens group L2 and the front lens group L1. The overall movement motor 18 and the rear group movement motor 21 are drive-controlled via respective motor control means 25 and 26. The movement position of the entire lens group is the zoom code means 41 provided between the fixed ring 11 and the front group support ring 13.
Is detected by the overall pulse encoder 42 that controls the rotational position of the overall movement motor 18. The zoom code means 41 detects all focal lengths as stepwise focal length information. Front group support ring 13 (front group lens L
The position of the rear lens group L2 with respect to 1) is controlled by the rear group pulse encoder 43. The rear group pulse encoder 43 includes means (switch) for determining the reference position of the rear group lens L2 with respect to the front group lens L1.

The camera body comprises a zoom operating means 31, a focus operating means (shutter release means) 32, a distance measuring means 33, and a photometric means 34. The zoom operation means 31 gives a zooming command, that is, a movement command from the wide side to the tele side and a movement command from the tele side to the wide side to the zoom lens including the front group lens L1 and the rear group lens L2. It consists of momentary switches. The shutter release means 32 is composed of a release button, and the distance measuring means 3 is pressed by pushing it one step.
A distance measurement command to the third lens group 3 and a light measurement command to the light metering means 34 are given, and the shutter 36 mounted on the front group support ring 13 is operated via the shutter control means 35 by two-step pressing. The shutter 36 receives the photometric output from the photometric means 34,
The shutter blade 36a is opened for a predetermined time.

In the zoom lens camera having the above structure, when the zoom operation means 31 is operated, the whole movement motor 18 is operated at least via the motor control means 25 to integrally move the front lens group L1 and the rear lens group L2. Let The rear group moving motor 21 may be operated simultaneously via the motor control means 26, but the important point is that the zoom operation means 3 is used.
It means that the movement of the front lens group L1 and the rear lens group L2 by 1 is not performed by the conventional zooming concept that the focus position does not move. That is, when the zoom operating means 31 is operated, only the whole moving motor 18 is operated to move the front lens group L.
1 and the rear lens group L2 are moved back and forth without changing the air gap between them, and both the overall movement motor 18 and the rear lens group movement motor 21 are operated to operate the front lens group L1 and the rear lens group L2. It is possible to move while changing the air gap between the two. In this mode, it is naturally impossible to focus on a specific subject at all times, but there is no problem in a compact camera that does not observe the image of the photographic optical system because it can be focused at the time of shutter release. Also in this mode, both lens groups are moved so that the focal position of the subject at a specific distance by the front lens group L1 and the rear lens group L2 is changed, and both the whole moving means and the rear group moving means are operated at the time of shutter release. Let me focus.

That is, in this zoom lens camera,
In this way, when the shutter release means 32 is operated in at least a part of the focal length range of the focal length set by the zoom operating means 31, both the whole moving motor 18 and the rear group moving motor 21 are operated to operate the subject. Focus on. At this time, the amount of movement of the front lens group L1 and the rear lens group L2 by the overall movement motor 18 and the rear group movement motor 21 is not limited to the amount of movement obtained by the object distance information by the distance measuring means 33, but by the zoom operation means 31. It is determined in consideration of the movement amount obtained by the set focal length information. In this way, the shutter release means 3
When both the total movement motor 18 and the rear group movement motor 21 are operated when the position 2 is operated, the degree of freedom in controlling the lens position is increased, and the control is facilitated.

Theoretically, when operating the zoom operating means 31, the whole moving motor 18 and the rear group moving motor 21 are operated.
The shutter release means 32 is operated by changing only the view field magnification and the focal length information of the finder without operating any of the above.
Is operated, the focal length information and distance measuring means 33
The overall movement motor 18 and the rear group movement motor 21 are simultaneously operated according to the subject distance information according to, and the front group lens L1 and the rear group lens L2 are moved to positions uniquely determined by the focal length information and the subject distance information. You can also let it.

The present invention calculates the number of pulses for driving the whole moving motor 18 and the number of pulses for driving the rear lens group moving motor 21 in the zoom lens camera having the above-described structure. Z _adj and fB _adj of
_Consider X _1adj (= fB _adj −Z _adj ). Whole movement motor 18 when the focus operating means 32 is operated
Is ZP _Z , and the drive pulse of the rear group movement motor 21 is AFP _Z , ZP _Z = aP _Z + bP _Z + X _1adj P _Z + cP _Z AFP _F = dAFP _F + eAFP _F + Z _adj P _F + fA
Given by FP _F. However, aP _Z : the number of pulses after the code edge is detected by the zoom code means, bP _Z : the number of zoom pulses according to the subject distance, X _1adj P _Z : the pulse necessary for advancing the front lens group L1 by X 1 _adj Number, cP _Z : correction pulse number for fine adjustment of the whole movement motor 18, dAFP _F : fixed pulse number, eAFP _F : focal length step detected by zoom code means and pulse number according to subject distance information, Z _adj P _F : Z for the front lens group L1 by the whole motor 18
Only _{adj is} extended, and the rear lens group L2 is _driven by the rear lens group motor 21.
Is the number of pulses required to return Z _adj (without moving the rear lens group L2), fAFP _F : The number of correction pulses for fine adjustment of the rear group movement motor 21.

To the CPU 50, X _1adj P _Z and Z _adj P _F calculated based on the shift amount y of the focus surface positions at the wide end and the tele end before zooming adjustment are input. The other respective pulse numbers are held as a table by the CPU 50, and the above calculation is performed every time the focusing operation, usually the photographing operation is executed, to drive the whole moving motor 18 and the rear group moving motor 21. . It should be noted that cP _Z and fAFP _F are the number of fine adjustment pulses necessary to eliminate the deviation, if any, as a result of measuring the focus position at each zoom step.

[0018]

As described above, according to the control method of the zoom lens camera of the present invention, mechanical zooming adjustment and f
By measuring the amount of deviation between the focal plane positions at the wide end and the tele end without making B adjustments and inputting the required calculation results, the lens drive that incorporates these adjustments at the same time as the focusing operation can be performed. You can

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of a control method for a zoom lens camera according to the present invention.

FIG. 2 is a diagram showing a specific example of a zoom lens camera to which the method of the present invention is applied.

FIG. 3 is a control block diagram of the camera of FIG.

[Explanation of symbols]

 L1 front group lens L2 rear group lens 11 fixed ring 12 drive ring 13 front group support ring 14 rear group support ring 18 whole movement motor 21 rear group movement motor 31 zoom operating means 32 focus operating means 41 zoom code means 42 overall pulse encoder 43 Rear group pulse encoder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sato ▲ Taku ▼ Ma 2 36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd. (72) Inventor Masaaki Kishimoto 2-chome, Maeno-cho, Itabashi-ku, Tokyo 36-9 Asahi Kogaku Kogyo Co., Ltd. (72) Inventor Hiroshi Nomura 2-chome Maeno-cho, Itabashi-ku, Tokyo 36-9 Asahi Kogaku Kogyo Co., Ltd. (72) Inventor Kazuyoshi Kamigami 2-chome Maeno-cho, Itabashi-ku, Tokyo 36-9 No. Asahi Gaku Kogyo Co., Ltd. (72) Inventor Keimitsu Sasaki 2-36 Maeno-cho, Itabashi-ku, Tokyo Inside Asahi Gaku Gaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A lens system having a movable front lens group and a rear lens group; a motor for moving the front lens group and the rear lens group integrally; a rear lens group with respect to the front lens group. In a zoom lens camera including a rear lens group motor; and a pulse encoder for controlling the rotational position of each motor, a first lens surface position is measured at a wide-angle end and a telephoto end to obtain a deviation amount in the optical axis direction. Step: Obtain the amount of movement required for the front lens group in order to match the focus surface positions at the wide-angle end and the telephoto end without moving the rear lens group, and move the rear lens group to the front lens group without moving it. The second step of obtaining the number of drive pulses of each motor required to give the movement amount; the focus plane position resulting from giving the movement amount to the front lens group is matched with the focal plane of the camera. The third step of obtaining the amount of movement of the front lens group and the rear lens group necessary for that, and the number of drive pulses of each motor required to give the movement amount to the front lens group and the rear lens group; The number of pulses obtained in the second step, the third
In consideration of the number of pulses obtained in the step, the number of pulses based on the focal length information, and the number of pulses based on the subject distance information, and controlling each of the motors during the focusing operation via the pulse encoder. A method for controlling a zoom lens camera, which is characterized in that